Progesterone, Inflammatory Cytokine (TNF-α), and Oxidative Stress (H2O2) Regulate Progesterone Receptor Membrane Component 1 Expression in Fetal Membrane Cells.

PubMed

Meng, Yan; Murtha, Amy P; Feng, Liping

2016-09-01

Progesterone receptor membrane component 1 (PGRMC1) is an important novel mediator of progesterone (P4) function in fetal membrane cells. We demonstrated previously that PGRMC1 is differentially expressed in fetal membranes among pregnancy subjects and diminished in preterm premature rupture of membrane subjects. In the current study, we aim to elucidate whether PGRMC1 expression is regulated by P4, tumor necrosis factor α (TNF-α), and H2O2 in fetal membrane cells. Primary cultured membrane cells were serum starved for 24 hours followed by treatments of P4, 17 hydroxyprogesterone caproate, and medroxyprogesterone 17 acetate (MPA) at 10(-7) mol/L with ethanol as vehicle control; TNF-α at 10, 20, and 50 ng/mL with phosphate-buffered saline (PBS) as control; and H2O2 at 10 and 100 μmol/L with culture media as control for 24, 48, and 72 hours. The messenger RNA (mRNA) and protein expression of PGRMC1 was quantified using polymerase chain reaction and Western blotting, respectively. We found that PGRMC1 protein expression was regulated by MPA, TNF-α, and H2O2 in a dose-dependent manner. This regulation is also specific to the type of cell (amnion, chorion, or decidua). The upregulation of PGRMC1 by MPA might be mediated through glucocorticoid receptor (GR) demonstrated using amnion and chorion cells model with GR knockdown by specific small interfering RNA transfection. The mRNA expression of PGRMC1 was decreased by H2O2 (100 μmol/L) treatment in amnion cells, which might ultimately result in downregulation of PGRMC1 protein as our data demonstrated. None of other treatments changed PGRMC1 mRNA level in these cells. We conclude that these stimuli act as regulatory factors of PGRMC1 in a cell-specific manner. © The Author(s) 2016.

Differential expression profile of membrane proteins in L-02 cells exposed to trichloroethylene.

PubMed

Hong, Wen-Xu; Huang, Aibo; Lin, Sheng; Yang, Xifei; Yang, Linqing; Zhou, Li; Huang, Haiyan; Wu, Desheng; Huang, Xinfeng; Xu, Hua; Liu, Jianjun

2016-10-01

Trichloroethylene (TCE), a halogenated organic solvent widely used in industries, is known to cause severe hepatotoxicity. However, the mechanisms underlying TCE hepatotoxicity are still not well understood. It is predicted that membrane proteins are responsible for key biological functions, and recent studies have revealed that TCE exposure can induce abnormal levels of membrane proteins in body fluids and cultured cells. The aim of this study is to investigate the TCE-induced alterations of membrane proteins profiles in human hepatic L-02 liver cells. A comparative membrane proteomics analysis was performed in combination with two-dimensional fluorescence difference gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry. A total of 15 proteins were identified as differentially expressed (4 upregulated and 11 downregulated) between TCE-treated cells and normal controls. Among this, 14 of them are suggested as membrane-associated proteins by their transmembrane domain and/or subcellular location. Furthermore, the differential expression of β subunit of adenosine triphosphate synthase (ATP5B) and prolyl 4-hydroxylase, β polypeptide (P4HB) were verified by Western blot analysis in TCE-treated L-02 cells. Our work not only reveals the association between TCE exposure and altered expression of membrane proteins but also provides a novel strategy to discover membrane biomarkers and elucidate the potential mechanisms involving with membrane proteins response to chemical-induced toxic effect. © The Author(s) 2015.

Purification of human adipose-derived stem cells from fat tissues using PLGA/silk screen hybrid membranes.

PubMed

Chen, Da-Chung; Chen, Li-Yu; Ling, Qing-Dong; Wu, Meng-Hsueh; Wang, Ching-Tang; Suresh Kumar, S; Chang, Yung; Munusamy, Murugan A; Alarfajj, Abdullah A; Wang, Han-Chow; Hsu, Shih-Tien; Higuchi, Akon

2014-05-01

The purification of human adipose-derived stem cells (hADSCs) from human adipose tissue cells (stromal vascular fraction) was investigated using membrane filtration through poly(lactide-co-glycolic acid)/silk screen hybrid membranes. Membrane filtration methods are attractive in regenerative medicine because they reduce the time required to purify hADSCs (i.e., less than 30 min) compared with conventional culture methods, which require 5-12 days. hADSCs expressing the mesenchymal stem cell markers CD44, CD73, and CD90 were concentrated in the permeation solution from the hybrid membranes. Expression of the surface markers CD44, CD73, and CD99 on the cells in the permeation solution from the hybrid membranes, which were obtained using 18 mL of feed solution containing 50 × 10⁴ cells, was statistically significantly higher than that of the primary adipose tissue cells, indicating that the hADSCs can be purified in the permeation solution by the membrane filtration method. Cells expressing the stem cell-associated marker CD34 could be successfully isolated in the permeation solution, whereas CD34⁺ cells could not be purified by the conventional culture method. The hADSCs in the permeation solution demonstrated a superior capacity for osteogenic differentiation based on their alkali phosphatase activity, their osterix gene expression, and the results of mineralization analysis by Alizarin Red S and von Kossa staining compared with the cells from the suspension of human adipose tissue. These results suggest that the hADSCs capable of osteogenic differentiation preferentially permeate through the hybrid membranes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Quantitative transporter proteomics by liquid chromatography with tandem mass spectrometry: addressing methodologic issues of plasma membrane isolation and expression-activity relationship.

PubMed

Kumar, Vineet; Prasad, Bhagwat; Patilea, Gabriela; Gupta, Anshul; Salphati, Laurent; Evers, Raymond; Hop, Cornelis E C A; Unadkat, Jashvant D

2015-02-01

To predict transporter-mediated drug disposition using physiologically based pharmacokinetic models, one approach is to measure transport activity and relate it to protein expression levels in cell lines (overexpressing the transporter) and then scale these to via in vitro to in vivo extrapolation (IVIVE). This approach makes two major assumptions. First, that the expression of the transporter is predominantly in the plasma membrane. Second, that there is a linear correlation between expression level and activity of the transporter protein. The present study was conducted to test these two assumptions. We evaluated two commercially available kits that claimed to separate plasma membrane from other cell membranes. The Qiagen Qproteome kit yielded very little protein in the fraction purported to be the plasma membrane. The Abcam Phase Separation kit enriched the plasma membrane but did not separate it from other intracellular membranes. For the Abcam method, the expression level of organic anion-transporting polypeptides (OATP) 1B1/2B1 and breast cancer resistance protein (BCRP) proteins in all subcellular fractions isolated from cells or human liver tissue tracked that of Na⁺-K⁺ ATPase. Assuming that Na⁺-K⁺ ATPase is predominantly located in the plasma membrane, these data suggest that the transporters measured are also primarily located in the plasma membrane. Using short hairpin RNA, we created clones of cell lines with varying degrees of OATP1B1 or BCRP expression level. In these clones, transport activity of OATP1B1 or BCRP was highly correlated with protein expression level (r² > 0.9). These data support the use of transporter expression level data and activity data from transporter overexpressing cell lines for IVIVE of transporter-mediated disposition of drugs. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Tula hantavirus L protein is a 250 kDa perinuclear membrane-associated protein.

PubMed

Kukkonen, Sami K J; Vaheri, Antti; Plyusnin, Alexander

2004-05-01

The complete open reading frame of Tula hantavirus (TULV) L RNA was cloned in three parts. The middle third (nt 2191-4344) could be expressed in E. coli and was used to immunize rabbits. The resultant antiserum was then used to immunoblot concentrated TULV and infected Vero E6 cells. The L protein of a hantavirus was detected, for the first time, in infected cells and was found to be expressed as a single protein with an apparent molecular mass of 250 kDa in both virions and infected cells. Using the antiserum, the expression level of the L protein was followed and image analysis of immunoblots indicated that there were 10(4) copies per cell at the peak level of expression. The antiserum was also used to detect the L protein in cell fractionation studies. In cells infected with TULV and cells expressing recombinant L, the protein pelleted with the microsomal membrane fraction. The membrane association was confirmed with membrane flotation assays. To visualize L protein localization in cells, a fusion protein of L and enhanced green fluorescent protein, L-EGFP, was expressed in Vero E6 cells with a plasmid-driven T7 expression system. L-EGFP localized in the perinuclear region where it had partial co-localization with the Golgi matrix protein GM130 and the TULV nucleocapsid protein.

Bacillus subtilis MreB orthologs self-organize into filamentous structures underneath the cell membrane in a heterologous cell system.

PubMed

Dempwolff, Felix; Reimold, Christian; Reth, Michael; Graumann, Peter L

2011-01-01

Actin-like bacterial cytoskeletal element MreB has been shown to be essential for the maintenance of rod cell shape in many bacteria. MreB forms rapidly remodelling helical filaments underneath the cell membrane in Bacillus subtilis and in other bacterial cells, and co-localizes with its two paralogs, Mbl and MreBH. We show that MreB localizes as dynamic bundles of filaments underneath the cell membrane in Drosophila S2 Schneider cells, which become highly stable when the ATPase motif in MreB is modified. In agreement with ATP-dependent filament formation, the depletion of ATP in the cells lead to rapid dissociation of MreB filaments. Extended induction of MreB resulted in the formation of membrane protrusions, showing that like actin, MreB can exert force against the cell membrane. Mbl also formed membrane associated filaments, while MreBH formed filaments within the cytosol. When co-expressed, MreB, Mbl and MreBH built up mixed filaments underneath the cell membrane. Membrane protein RodZ localized to endosomes in S2 cells, but localized to the cell membrane when co-expressed with Mbl, showing that bacterial MreB/Mbl structures can recruit a protein to the cell membrane. Thus, MreB paralogs form a self-organizing and dynamic filamentous scaffold underneath the membrane that is able to recruit other proteins to the cell surface.

Embryoid body attachment to reconstituted basement membrane induces a genetic program of epithelial differentiation via jun N-terminal kinase signaling.

PubMed

Ho, Hoang-Yen; Moffat, Ryan C; Patel, Rupal V; Awah, Franklin N; Baloue, Kaitrin; Crowe, David L

2010-09-01

Embryonic stem (ES) cells are derived from early stage mammalian embryos and have broad developmental potential. These cells can be manipulated experimentally to generate cells of multiple tissue types which could be important in treating human diseases. The ability to produce relevant amounts of these differentiated cell populations creates the basis for clinical interventions in tissue regeneration and repair. Understanding how embryonic stem cells differentiate also can reveal important insights into cell biology. A previously reported mouse embryonic stem cell model demonstrated that differentiated epithelial cells migrated out of embryoid bodies attached to reconstituted basement membrane. We used genomic technology to profile ES cell populations in order to understand the molecular mechanisms leading to epithelial differentiation. Cells with characteristics of cultured epithelium migrated from embryoid bodies attached to reconstituted basement membrane. However, cells that comprised embryoid bodies also rapidly lost ES cell-specific gene expression and expressed proteins characteristic of stratified epithelia within hours of attachment to basement membrane. Gene expression profiling of sorted cell populations revealed upregulation of the BMP/TGFbeta signaling pathway, which was not sufficient for epithelial differentiation in the absence of basement membrane attachment. Activation of c-jun N-terminal kinase 1 (JNK1) and increased expression of Jun family transcription factors was observed during epithelial differentiation of ES cells. Inhibition of JNK signaling completely blocked epithelial differentiation in this model, revealing a key mechanism by which ES cells adopt epithelial characteristics via basement membrane attachment. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Tissue-specific expression of the gene for a putative plasma membrane H(+)-ATPase in a seagrass.

PubMed Central

Fukuhara, T; Pak, J Y; Ohwaki, Y; Tsujimura, H; Nitta, T

1996-01-01

A cDNA clone corresponding to the gene (ZHA1) for a putative plasma membrane H(+)-ATPase of a seagrass (Zostera marina L.) was isolated and sequenced. Comparison of the amino acid predicted sequence from the nucleotide sequence of ZHA1 with those encoded by known genes for plasma membrane H(+)-ATPases from other plants indicated that ZHA1 is most similar to the gene (PMA4) for a plasma membrane H(+)-ATPase in a tobacco (84.4%). Northern hybridization indicated that ZHA1 was strongly expressed in mature leaves, which are exposed to seawater and have the ability of tolerate salinity; ZHA1 was weakly expressed in immature leaves, which are protected from seawater by tightly enveloping sheaths and are sensitive to salinity. In mature leaves, in situ hybridization revealed that ZHA1 was expressed specifically in epidermal cells, the plasma membranes of which were highly invaginated and morphologically similar to those of typical transfer cells. Therefore, the differentiation of the transfer cell-like structures, accompanied by the high-level expression of ZHA1, in the epidermal cells of mature leaves in particular may be important for the excretion of salt by these cells. PMID:8587992

Attachment, proliferation and collagen type I mRNA expression of human gingival fibroblasts on different biodegradable membranes.

PubMed

Hakki, Sema S; Korkusuz, Petek; Purali, Nuhan; Bozkurt, Buket; Kus, Mahmut; Duran, Ismet

2013-01-01

The purpose of this study was to investigate adhesion, proliferation and type I collagen (COL I) mRNA expression of gingival fibroblasts on different membranes used in periodontal applications. Collagen (C), acellular dermal matrix (ADM) and polylactic acid; polyglycolic acid; lactide/glycolide copolymer (PLGA) biodegradable membranes were combined with gingival fibroblasts in culture and incubated for 48 h. Cell adhesion was examined with scanning electron and confocal microscopy. MTT assay was used to measure proliferation. COL I mRNA expression was assessed using quantitative-polymerase chain reaction (QPCR). The PLGA group exhibited the lowest cell survival on day 5 and 10, and lowest cell proliferation on days 5, 10 and 14. While cell proliferation was similar in C and ADM groups, the C membrane showed a slightly greater increase in viable cells to day 10. Confocal and scanning electron microscopy confirmed the results of proliferation and MTT assays. The highest COL I mRNA expression was noted in the PLGA membrane group when compared to the C (p < 0.01) and ADM (p < 0.05) membrane groups. These data revealed that adherence and proliferation of primary gingival fibroblasts on collagen-based C and ADM membranes is better than that seen with PLGA membranes, and thus may be preferable in the treatment of gingival recession defects.

Tunable Control of an Escherichia coli Expression System for the Overproduction of Membrane Proteins by Titrated Expression of a Mutant lac Repressor.

PubMed

Kim, Seong Keun; Lee, Dae-Hee; Kim, Oh Cheol; Kim, Jihyun F; Yoon, Sung Ho

2017-09-15

Most inducible expression systems suffer from growth defects, leaky basal induction, and inhomogeneous expression levels within a host cell population. These difficulties are most prominent with the overproduction of membrane proteins that are toxic to host cells. Here, we developed an Escherichia coli inducible expression system for membrane protein production based on titrated expression of a mutant lac repressor (mLacI). Performance of the mLacI inducible system was evaluated in conjunction with commonly used lac operator-based expression vectors using a T7 or tac promoter. Remarkably, expression of a target gene can be titrated by the dose-dependent addition of l-rhamnose, and the expression levels were homogeneous in the cell population. The developed system was successfully applied to overexpress three membrane proteins that were otherwise difficult to produce in E. coli. This gene expression control system can be easily applied to a broad range of existing protein expression systems and should be useful in constructing genetic circuits that require precise output signals.

Inhibition of laminin alpha 1-chain expression leads to alteration of basement membrane assembly and cell differentiation

PubMed Central

1996-01-01

The expression of the constituent alpha 1 chain of laminin-1, a major component of basement membranes, is markedly regulated during development and differentiation. We have designed an antisense RNA strategy to analyze the direct involvement of the alpha 1 chain in laminin assembly, basement membrane formation, and cell differentiation. We report that the absence of alpha 1-chain expression, resulting from the stable transfection of the human colonic cancer Caco2 cells with an eukaryotic expression vector comprising a cDNA fragment of the alpha 1 chain inserted in an antisense orientation, led to (a) an incorrect secretion of the two other constituent chains of laminin-1, the beta 1/gamma 1 chains, (b) the lack of basement membrane assembly when Caco2-deficient cells were cultured on top of fibroblasts, assessed by the absence of collagen IV and nidogen deposition, and (c) changes in the structural polarity of cells accompanied by the inhibition of an apical digestive enzyme, sucrase-isomaltase. The results demonstrate that the alpha 1 chain is required for secretion of laminin-1 and for the assembly of basement membrane network. Furthermore, expression of the laminin alpha 1-chain gene may be a regulatory element in determining cell differentiation. PMID:8609173

RGMb protects against acute kidney injury by inhibiting tubular cell necroptosis via an MLKL-dependent mechanism.

PubMed

Liu, Wenjing; Chen, Binbin; Wang, Yang; Meng, Chenling; Huang, Huihui; Huang, Xiao-Ru; Qin, Jinzhong; Mulay, Shrikant R; Anders, Hans-Joachim; Qiu, Andong; Yang, Baoxue; Freeman, Gordon J; Lu, Hua Jenny; Lin, Herbert Y; Zheng, Zhi-Hua; Lan, Hui-Yao; Huang, Yu; Xia, Yin

2018-02-13

Tubular cell necrosis is a key histological feature of acute kidney injury (AKI). Necroptosis is a type of programed necrosis, which is executed by mixed lineage kinase domain-like protein (MLKL) upon its binding to the plasma membrane. Emerging evidence indicates that necroptosis plays a critical role in the development of AKI. However, it is unclear whether renal tubular cells undergo necroptosis in vivo and how the necroptotic pathway is regulated during AKI. Repulsive guidance molecule (RGM)-b is a member of the RGM family. Our previous study demonstrated that RGMb is highly expressed in kidney tubular epithelial cells, but its biological role in the kidney has not been well characterized. In the present study, we found that RGMb reduced membrane-associated MLKL levels and inhibited necroptosis in cultured cells. During ischemia/reperfusion injury (IRI) or oxalate nephropathy, MLKL was induced to express on the apical membrane of proximal tubular (PT) cells. Specific knockout of Rgmb in tubular cells (Rgmb cKO) increased MLKL expression at the apical membrane of PT cells and induced more tubular cell death and more severe renal dysfunction compared with wild-type mice. Treatment with the necroptosis inhibitor Necrostatin-1 or GSK'963 reduced MLKL expression on the apical membrane of PT cells and ameliorated renal function impairment after IRI in both wild-type and Rgmb cKO mice. Taken together, our results suggest that proximal tubular cell necroptosis plays an important role in AKI, and that RGMb protects against AKI by inhibiting MLKL membrane association and necroptosis in proximal tubular cells.

Bacillus subtilis MreB Orthologs Self-Organize into Filamentous Structures underneath the Cell Membrane in a Heterologous Cell System

PubMed Central

Dempwolff, Felix; Reimold, Christian; Reth, Michael; Graumann, Peter L.

2011-01-01

Actin-like bacterial cytoskeletal element MreB has been shown to be essential for the maintenance of rod cell shape in many bacteria. MreB forms rapidly remodelling helical filaments underneath the cell membrane in Bacillus subtilis and in other bacterial cells, and co-localizes with its two paralogs, Mbl and MreBH. We show that MreB localizes as dynamic bundles of filaments underneath the cell membrane in Drosophila S2 Schneider cells, which become highly stable when the ATPase motif in MreB is modified. In agreement with ATP-dependent filament formation, the depletion of ATP in the cells lead to rapid dissociation of MreB filaments. Extended induction of MreB resulted in the formation of membrane protrusions, showing that like actin, MreB can exert force against the cell membrane. Mbl also formed membrane associated filaments, while MreBH formed filaments within the cytosol. When co-expressed, MreB, Mbl and MreBH built up mixed filaments underneath the cell membrane. Membrane protein RodZ localized to endosomes in S2 cells, but localized to the cell membrane when co-expressed with Mbl, showing that bacterial MreB/Mbl structures can recruit a protein to the cell membrane. Thus, MreB paralogs form a self-organizing and dynamic filamentous scaffold underneath the membrane that is able to recruit other proteins to the cell surface. PMID:22069484

Over-expression of mammalian sialidase NEU3 reduces Newcastle disease virus entry and propagation in COS7 cells.

PubMed

Anastasia, Luigi; Holguera, Javier; Bianchi, Anna; D'Avila, Francesca; Papini, Nadia; Tringali, Cristina; Monti, Eugenio; Villar, Enrique; Venerando, Bruno; Muñoz-Barroso, Isabel; Tettamanti, Guido

2008-03-01

The paramyxovirus Newcastle Disease Virus (NDV) binds to sialic acid-containing glycoconjugates, sialoglycoproteins and sialoglycolipids (gangliosides) of host cell plasma membrane through its hemagglutinin-neuraminidase (sialidase) HN glycoprotein. We hypothesized that the modifications of the cell surface ganglioside pattern determined by over-expression of the mammalian plasma-membrane associated, ganglioside specific, sialidase NEU3 would affect the virus-host cell interactions. Using COS7 cells as a model system, we observed that over-expression of the murine MmNEU3 did not affect NDV binding but caused a marked reduction in NDV infection and virus propagation through cell-cell fusion. Moreover, since GD1a was greatly reduced in COS7 cells following NEU3-over-expression, we added [(3)H]-labelled GD1a to COS7 cells under conditions that block intralysosomal metabolic processing, and we observed a marked increase of GD1a cleavage to GM1 during NDV infection, indicating a direct involvement of the virus sialidase and host cell GD1a in NDV infectivity. Therefore, the decrease of GD1a in COS7 cell membrane upon MmNEU3 over-expression is likely to be instrumental to NDV reduced infection. Evidence was also provided for the preferential association of NDV-HN at 4 degrees C to detergent resistant microdomains (DRMs) of COS7 cells plasma membranes.

Prostate cancer targeting motifs: expression of αν β3, neurotensin receptor 1, prostate specific membrane antigen, and prostate stem cell antigen in human prostate cancer cell lines and xenografts.

PubMed

Taylor, Robert M; Severns, Virginia; Brown, David C; Bisoffi, Marco; Sillerud, Laurel O

2012-04-01

Membrane receptors are frequent targets of cancer therapeutic and imaging agents. However, promising in vitro results often do not translate to in vivo clinical applications. To better understand this obstacle, we measured the expression differences in receptor signatures among several human prostate cancer cell lines and xenografts as a function of tumorigenicity. Messenger RNA and protein expression levels for integrin α(ν) β(3), neurotensin receptor 1 (NTSR1), prostate specific membrane antigen (PSMA), and prostate stem cell antigen (PSCA) were measured in LNCaP, C4-2, and PC-3 human prostate cancer cell lines and in murine xenografts using quantitative reverse transcriptase polymerase chain reaction, flow cytometry, and immunohistochemistry. Stable expression patterns were observed for integrin α(ν) and PSMA in all cells and corresponding xenografts. Integrin β(3) mRNA expression was greatly reduced in C4-2 xenografts and greatly elevated in PC-3 xenografts compared with the corresponding cultured cells. NTSR1 mRNA expression was greatly elevated in LNCaP and PC-3 xenografts. PSCA mRNA expression was elevated in C4-2 xenografts when compared with C4-2 cells cultured in vitro. Furthermore, at the protein level, PSCA was re-expressed in all xenografts compared with cells in culture. The regulation of mRNA and protein expression of the cell-surface target proteins α(ν) β(3), NTSR1, PSMA, and PSCA, in prostate cancer cells with different tumorigenic potential, was influenced by factors of the microenvironment, differing between cell cultures and murine xenotransplants. Integrin α(ν) β(3), NTRS1 and PSCA mRNA expression increased with tumorigenic potential, but mRNA expression levels for these proteins do not translate directly to equivalent expression levels of membrane bound protein. Copyright © 2011 Wiley Periodicals, Inc.

Comparative proteomic investigation of metastatic and non-metastatic osteosarcoma cells of human and canine origin

PubMed Central

Roy, Jahnabi; Wycislo, Kathryn L.; Pondenis, Holly; Fan, Timothy M.

2017-01-01

Osteosarcoma is the most common bone cancer in dogs and people. In order to improve clinical outcomes, it is necessary to identify proteins that are differentially expressed by metastatic cells. Membrane bound proteins are responsible for multiple pro-metastatic functions. Therefore characterizing the differential expression of membranous proteins between metastatic and non-metastatic clonal variants will allow the discovery of druggable targets and consequently improve treatment methodology. The objective of this investigation was to systemically identify the membrane-associated proteomics of metastatic and non-metastatic variants of human and canine origin. Two clonal variants of divergent in vivo metastatic potential from human and canine origins were used. The plasma membranes were isolated and peptide fingerprinting was used to identify differentially expressed proteins. Selected proteins were further validated using western blotting, flow cytometry, confocal microscopy and immunohistochemistry. Over 500 proteins were identified for each cell line with nearly 40% of the proteins differentially regulated. Conserved between both species, metastatic variants demonstrated significant differences in expression of membrane proteins that are responsible for pro-metastatic functions. Additionally, CD147, CD44 and vimentin were validated using various biochemical techniques. Taken together, through a comparative proteomic approach we have identified several differentially expressed cell membrane proteins that will help in the development of future therapeutics. PMID:28910304

Comparative proteomic investigation of metastatic and non-metastatic osteosarcoma cells of human and canine origin.

PubMed

Roy, Jahnabi; Wycislo, Kathryn L; Pondenis, Holly; Fan, Timothy M; Das, Aditi

2017-01-01

Osteosarcoma is the most common bone cancer in dogs and people. In order to improve clinical outcomes, it is necessary to identify proteins that are differentially expressed by metastatic cells. Membrane bound proteins are responsible for multiple pro-metastatic functions. Therefore characterizing the differential expression of membranous proteins between metastatic and non-metastatic clonal variants will allow the discovery of druggable targets and consequently improve treatment methodology. The objective of this investigation was to systemically identify the membrane-associated proteomics of metastatic and non-metastatic variants of human and canine origin. Two clonal variants of divergent in vivo metastatic potential from human and canine origins were used. The plasma membranes were isolated and peptide fingerprinting was used to identify differentially expressed proteins. Selected proteins were further validated using western blotting, flow cytometry, confocal microscopy and immunohistochemistry. Over 500 proteins were identified for each cell line with nearly 40% of the proteins differentially regulated. Conserved between both species, metastatic variants demonstrated significant differences in expression of membrane proteins that are responsible for pro-metastatic functions. Additionally, CD147, CD44 and vimentin were validated using various biochemical techniques. Taken together, through a comparative proteomic approach we have identified several differentially expressed cell membrane proteins that will help in the development of future therapeutics.

4-phenylbutyrate enhances the cell surface expression and the transport capacity of wild-type and mutated bile salt export pumps.

PubMed

Hayashi, Hisamitsu; Sugiyama, Yuichi

2007-06-01

Progressive familial intrahepatic cholestasis type 2 (PFIC2) is caused by a mutation in the bile salt export pump (BSEP/ABCB11) gene. We previously reported that E297G and D482G BSEP, which are frequently found mutations in European patients, result in impaired membrane trafficking, whereas both mutants retain their transport function. The dysfunctional localization is probably attributable to the retention of BSEP in endoplasmic reticulum (ER) followed by proteasomal degradation. Because sodium 4-phenylbutyrate (4PBA) has been shown to restore the reduced cell surface expression of mutated plasma membrane proteins, in the current study, we investigated the effect of 4PBA treatment on E297G and D482G BSEP. Transcellular transport and cell surface biotinylation studies using Madin-Darby canine kidney (MDCK) II cells demonstrated that 4PBA treatment increased functional cell surface expression of wild-type (WT), E297G, and D482G BSEP. The prolonged half-life of cell surface-resident BSEP with 4PBA treatment was responsible for this result. Moreover, treatment of Sprague-Dawley rats with 4PBA resulted in an increase in BSEP expression at the canalicular membrane, which was accompanied by an increase in the biliary excretion of [(3)H]taurocholic acid (TC). 4PBA treatment with a clinically achievable concentration enhances the cell surface expression and the transport capacity of WT, E297G, and D482G BSEP in MDCK II cells, and also induces functional BSEP expression at the canalicular membrane and bile acid transport via canalicular membrane in vivo. 4PBA is a potential pharmacological agent for treating not only PFIC2 patients with E297G and D482G mutations but also other cholestatic patients, in whom the BSEP expression at the canalicular membrane is reduced.

Proteinase 3 Is a Phosphatidylserine-binding Protein That Affects the Production and Function of Microvesicles.

PubMed

Martin, Katherine R; Kantari-Mimoun, Chahrazade; Yin, Min; Pederzoli-Ribeil, Magali; Angelot-Delettre, Fanny; Ceroi, Adam; Grauffel, Cédric; Benhamou, Marc; Reuter, Nathalie; Saas, Philippe; Frachet, Philippe; Boulanger, Chantal M; Witko-Sarsat, Véronique

2016-05-13

Proteinase 3 (PR3), the autoantigen in granulomatosis with polyangiitis, is expressed at the plasma membrane of resting neutrophils, and this membrane expression increases during both activation and apoptosis. Using surface plasmon resonance and protein-lipid overlay assays, this study demonstrates that PR3 is a phosphatidylserine-binding protein and this interaction is dependent on the hydrophobic patch responsible for membrane anchorage. Molecular simulations suggest that PR3 interacts with phosphatidylserine via a small number of amino acids, which engage in long lasting interactions with the lipid heads. As phosphatidylserine is a major component of microvesicles (MVs), this study also examined the consequences of this interaction on MV production and function. PR3-expressing cells produced significantly fewer MVs during both activation and apoptosis, and this reduction was dependent on the ability of PR3 to associate with the membrane as mutating the hydrophobic patch restored MV production. Functionally, activation-evoked MVs from PR3-expressing cells induced a significantly larger respiratory burst in human neutrophils compared with control MVs. Conversely, MVs generated during apoptosis inhibited the basal respiratory burst in human neutrophils, and those generated from PR3-expressing cells hampered this inhibition. Given that membrane expression of PR3 is increased in patients with granulomatosis with polyangiitis, MVs generated from neutrophils expressing membrane PR3 may potentiate oxidative damage of endothelial cells and promote the systemic inflammation observed in this disease. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Proteinase 3 Is a Phosphatidylserine-binding Protein That Affects the Production and Function of Microvesicles*

PubMed Central

Martin, Katherine R.; Kantari-Mimoun, Chahrazade; Yin, Min; Pederzoli-Ribeil, Magali; Angelot-Delettre, Fanny; Ceroi, Adam; Grauffel, Cédric; Benhamou, Marc; Reuter, Nathalie; Saas, Philippe; Frachet, Philippe; Boulanger, Chantal M.; Witko-Sarsat, Véronique

2016-01-01

Proteinase 3 (PR3), the autoantigen in granulomatosis with polyangiitis, is expressed at the plasma membrane of resting neutrophils, and this membrane expression increases during both activation and apoptosis. Using surface plasmon resonance and protein-lipid overlay assays, this study demonstrates that PR3 is a phosphatidylserine-binding protein and this interaction is dependent on the hydrophobic patch responsible for membrane anchorage. Molecular simulations suggest that PR3 interacts with phosphatidylserine via a small number of amino acids, which engage in long lasting interactions with the lipid heads. As phosphatidylserine is a major component of microvesicles (MVs), this study also examined the consequences of this interaction on MV production and function. PR3-expressing cells produced significantly fewer MVs during both activation and apoptosis, and this reduction was dependent on the ability of PR3 to associate with the membrane as mutating the hydrophobic patch restored MV production. Functionally, activation-evoked MVs from PR3-expressing cells induced a significantly larger respiratory burst in human neutrophils compared with control MVs. Conversely, MVs generated during apoptosis inhibited the basal respiratory burst in human neutrophils, and those generated from PR3-expressing cells hampered this inhibition. Given that membrane expression of PR3 is increased in patients with granulomatosis with polyangiitis, MVs generated from neutrophils expressing membrane PR3 may potentiate oxidative damage of endothelial cells and promote the systemic inflammation observed in this disease. PMID:26961880

Effect of Overproduction of Mitochondrial Uncoupling Protein 2 on Cos7 Cells: Induction of Senescent-like Morphology and Oncotic Cell Death.

PubMed

Nishio, Koji; Ma, Qian

2016-01-01

The maintenance of mitochondrial membrane potential is essential for cell growth and survival. Mitochondrial uncoupling protein 2 plays the most important roles in uncoupling oxidative phosphorylation and decreasing mitochondrial O2- production by regulating the mitochondrial membrane potential. We propose that mouse UCP2 has two glycine-rich motifs, motif 1: EGIRGLWKG (170-178) and a known Walker A-like motif 2: EGPRAFYKG (264-272). These motifs seem to be important for the function of UCP2. We investigated the biological effects of overproduced-UCP2 and its physiological consequence in Cos7 cells. We introduced several amino acid changes in the motif 1. The expression vectors of the green fluorescent protein (GFP)-fused UCP2 and mutant UCP2 were constructed and expressed in Cos7 cells. The UCP2-GFP-expressed cells significantly down-regulated the mitochondrial membrane potentials and induced the enlarged cell shapes. Next we generated the stably UCP2-GFP-expressed Cos7 cells by selection with the antibiotic Genecitin (G418). Within the first few weeks following G418-selection, the stably UCP2-GFP-expressed cells could not divide well and gradually manifested the irregular and enlarged senescent-like cell morphology. The UCP2/K177E- or UCP2/G174L-expressed cells did not induce the enlarged cell shapes. Hence, UCP2/K177E and UCP2/G174L produced the functional incompetence of the glycine-rich motif 1. The senescent-like cells significantly decreased the mitochondrial membrane potentials and finally died nearly one month. Overproduction of UCP2 irreversibly reduces the mitochondrial membrane potentials and induces the senescent-like morphology and finally oncotic cell death in Cos7 cells. These changes seem to occur from the irreversible metabolic changes following total loss of cellular ATP.

Neuroglian-mediated cell adhesion induces assembly of the membrane skeleton at cell contact sites

PubMed Central

1996-01-01

The protein ankyrin links integral membrane proteins to the spectrin- based membrane skeleton. Ankyrin is often concentrated within restricted membrane domains of polarized epithelia and neurons, but the mechanisms responsible for membrane targeting and its segregation within a continuous lipid bilayer remain unexplained. We provide evidence that neuroglian, a cell adhesion molecule related to L1 and neurofascin, can transmit positional information directly to ankyrin and thereby polarize its distribution in Drosophila S2 tissue culture cells. Ankyrin was not normally associated with the plasma membrane of these cells. Upon expression of an inducible neuroglian minigene, however, cells aggregated into large clusters and ankyrin became concentrated at sites of cell-cell contact. Spectrin was also recruited to sites of cell contact in response to neuroglian expression. The accumulation of ankyrin at cell contacts required the presence of the cytoplasmic domain of neuroglian since a glycosyl phosphatidylinositol- linked form of neuroglian failed to recruit ankyrin to sites of cell- cell contact. Double-labeling experiments revealed that, whereas ankyrin was strictly associated with sites of cell-cell contact, neuroglian was more broadly distributed over the cell surface. A direct interaction between neuroglian and ankyrin was demonstrated using yeast two-hybrid analysis. Thus, neuroglian appears to be activated by extracellular adhesion so that ankyrin and the membrane skeleton selectively associate with sites of cell contact and not with other regions of the plasma membrane. PMID:8636238

Neuroglian-mediated cell adhesion induces assembly of the membrane skeleton at cell contact sites.

PubMed

Dubreuil, R R; MacVicar, G; Dissanayake, S; Liu, C; Homer, D; Hortsch, M

1996-05-01

The protein ankyrin links integral membrane proteins to the spectrin-based membrane skeleton. Ankyrin is often concentrated within restricted membrane domains of polarized epithelia and neurons, but the mechanisms responsible for membrane targeting and its segregation within a continuous lipid bilayer remain unexplained. We provide evidence that neuroglian, a cell adhesion molecule related to L1 and neurofascin, can transmit positional information directly to ankyrin and thereby polarize its distribution in Drosophila S2 tissue culture cells. Ankyrin was not normally associated with the plasma membrane of these cells. Upon expression of an inducible neuroglian minigene, however, cells aggregated into large clusters and ankyrin became concentrated at sites of cell-cell contact. Spectrin was also recruited to sites of cell contact in response to neuroglian expression. The accumulation of ankyrin at cell contacts required the presence of the cytoplasmic domain of neuroglian since a glycosyl phosphatidylinositol-linked form of neuroglian failed to recruit ankyrin to sites of cell-cell contact. Double-labeling experiments revealed that, whereas ankyrin was strictly associated with sites of cell-cell contact, neuroglian was more broadly distributed over the cell surface. A direct interaction between neuroglian and ankyrin was demonstrated using yeast two-hybrid analysis. Thus, neuroglian appears to be activated by extracellular adhesion so that ankyrin and the membrane skeleton selectively associate with sites of cell contact and not with other regions of the plasma membrane.

The hydroxyflavone, fisetin, suppresses mast cell activation induced by interaction with activated T cell membranes

PubMed Central

Nagai, K; Takahashi, Y; Mikami, I; Fukusima, T; Oike, H; Kobori, M

2009-01-01

Background and purpose: Cell-to-cell interactions between mast cells and activated T cells are increasingly recognized as a possible mechanism in the aetiology of allergic or non-allergic inflammatory disorders. To determine the anti-allergic effect of fisetin, we examined the ability of fisetin to suppress activation of the human mast cell line, HMC-1, induced by activated Jurkat T cell membranes. Experimental approach: HMC-1 cells were incubated with or without fisetin for 15 min and then co-cultured with Jurkat T cell membranes activated by phorbol-12-myristate 13-acetate for 16 h. We determined gene expression in activated HMC-1 cells by DNA microarray and quantitative reverse transcription (RT)-PCR analysis. We also examined activation of the transcription factor NF-κB and MAP kinases (MAPKs) in activated HMC-1 cells. Key results: Fisetin suppresses cell spreading and gene expression in HMC-1 cells stimulated by activated T cell membranes. Additionally, we show that these stimulated HMC-1 cells expressed granzyme B. The stimulatory interaction also induced activation of NF-κB and MAPKs; these activations were suppressed by fisetin. Fisetin also reduced the amount of cell surface antigen CD40 and intercellular adhesion molecule-1 (ICAM-1) on activated HMC-1 cells. Conclusions and implications: Fisetin suppressed activation of HMC-1 cells by activated T cell membranes by interfering with cell-to-cell interaction and inhibiting the activity of NF-κB and MAPKs and thereby suppressing gene expression. Fisetin may protect against the progression of inflammatory diseases by limiting interactions between mast cells and activated T cells. PMID:19702784

Differences in Env and Gag protein expression patterns and epitope availability in feline immunodeficiency virus infected PBMC compared to infected and transfected feline model cell lines.

PubMed

Roukaerts, Inge D M; Grant, Chris K; Theuns, Sebastiaan; Christiaens, Isaura; Acar, Delphine D; Van Bockstael, Sebastiaan; Desmarets, Lowiese M B; Nauwynck, Hans J

2017-01-02

Env and Gag are key components of the FIV virion that are targeted to the plasma membrane for virion assembly. They are both important stimulators and targets of anti-FIV immunity. To investigate and compare the expression pattern and antigenic changes of Gag and Env in various research models, infected PBMC (the natural FIV host cells) and GFox, and transfected CrFK were stained over time with various Env and Gag specific MAbs. In FIV infected GFox and PBMC, Env showed changes in epitope availability for antibody binding during processing and trafficking, which was not seen in transfected CrFK. Interestingly, epitopes exposed on intracellular Env and Env present on the plasma membrane of CrFK and GFox seem to be hidden on plasma membrane expressed Env of FIV infected PBMC. A kinetic follow up of Gag and Env expression showed a polarization of both Gag and Env expression to specific sites at the plasma membrane of PBMC, but not in other cell lines. In conclusion, mature trimeric cell surface expressed Env might be antigenically distinct from intracellular monomeric Env in PBMC and might possibly be unrecognizable by feline humoral immunity. In addition, Env expression is restricted to a small area on the plasma membrane and co-localizes with a large moiety of Gag, which may represent a preferred FIV budding site, or initiation of virological synapses with direct cell-to-cell virus transmission. Copyright © 2016. Published by Elsevier B.V.

The absence of p53 during Human Cytomegalovirus infection leads to decreased UL53 expression, disrupting UL50 localization to the inner nuclear membrane, and thereby inhibiting capsid nuclear egress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuan, Man I; O’Dowd, John M.; Fortunato, Elizabeth

Our electron microscopy study (Kuan et al., 2016) found HCMV nuclear capsid egress was significantly reduced in p53 knockout cells (p53KOs), correlating with inhibited formation of infoldings of the inner nuclear membrane (IINMs). Molecular examination of these phenomena has found p53KOs expressed UL97 and phosphorylated lamins, however the lamina failed to remodel. The nuclear egress complex (NEC) protein UL50 was expressed in almost all cells. UL50 re-localized to the inner nuclear membrane (INM) in ~90% of wt cells, but only ~35% of p53KOs. UL53 expression was significantly reduced in p53KOs, and cells lacking UL50 nuclear staining, expressed no UL53. Re-introductionmore » of p53 into p53KOs largely recovered UL53 positivity and UL50 nuclear re-localization. Nuclear rim located UL50/53 puncta, which co-localized with the major capsid protein, were largely absent in p53KOs. We believe these puncta were IINMs. In the absence of p53, UL53 expression was inhibited, disrupting formation of the NEC/IINMs, and reducing functional virion secretion. -- Highlights: •Phosphorylated nuclear lamins were inefficiently remodeled in p53KO cells. •p53KO cells expressed UL50, but it was not efficiently targeted to the nuclear rim. •UL53 was not expressed in the large majority of p53KO cells. •Cells failing to express UL53 did not localize UL50 to the nucleus. •NEC puncta/infoldings of the inner nuclear membrane were scarce in p53KO cells.« less

Expression of a constitutively activated plasma membrane H+-ATPase in Nicotiana tabacum BY-2 cells results in cell expansion.

PubMed

Niczyj, Marta; Champagne, Antoine; Alam, Iftekhar; Nader, Joseph; Boutry, Marc

2016-11-01

Increased acidification of the external medium by an activated H + -ATPase results in cell expansion, in the absence of upstream activating signaling. The plasma membrane H + -ATPase couples ATP hydrolysis with proton transport outside the cell, and thus creates an electrochemical gradient, which energizes secondary transporters. According to the acid growth theory, this enzyme is also proposed to play a major role in cell expansion, by acidifying the external medium and so activating enzymes that are involved in cell wall-loosening. However, this theory is still debated. To challenge it, we made use of a plasma membrane H + -ATPase isoform from Nicotiana plumbaginifolia truncated from its C-terminal auto-inhibitory domain (ΔCPMA4), and thus constitutively activated. This protein was expressed in Nicotiana tabacum BY-2 suspension cells using a heat shock inducible promoter. The characterization of several independent transgenic lines showed that the expression of activated ΔCPMA4 resulted in a reduced external pH by 0.3-1.2 units, as well as in an increased H + -ATPase activity by 77-155 % (ATP hydrolysis), or 70-306 % (proton pumping) of isolated plasma membranes. In addition, ΔCPMA4-expressing cells were 17-57 % larger than the wild-type cells and displayed abnormal shapes. A proteomic comparison of plasma membranes isolated from ΔCPMA4-expressing and wild-type cells revealed the altered abundance of several proteins involved in cell wall synthesis, transport, and signal transduction. In conclusion, the data obtained in this work showed that H + -ATPase activation is sufficient to induce cell expansion and identified possible actors which intervene in this process.

An ESIPT fluorescent probe sensitive to protein α-helix structures.

PubMed

Jiang, Nan; Yang, Chanli; Dong, Xiongwei; Sun, Xianglang; Zhang, Dan; Liu, Changlin

2014-07-28

A large majority of membrane proteins have one or more transmembrane regions consisting of α-helices. Membrane protein levels differ from one type of cell to another, and the expression of membrane proteins also changes from normal to diseased cells. For example, prostate cancer cells have been reported to have downregulated expression of membrane proteins, including zinc transporters, compared with normal prostate cells. These reports inspired us to design a fluorescence probe sensitive to protein α-helical structures to discriminate individual prostate cancer cells from normal ones. A benzazole derivative ( in this study) was observed to emit strong fluorescence resulting from an excited-state intramolecular proton transfer (ESIPT) in protein α-helical environments. The intensity of ESIPT fluorescence of was observed to be positively correlated with the α-helix content of proteins. The molecular docking simulation suggested that it had low energy for the binding of to proteins when the binding sites were localized within the α-helical regions of protein via H-bonds. Furthermore, was found to be localized in cell membranes through binding to transmembrane α-helical regions of membrane proteins, and was capable of probing differences in the α-helix contents of membrane proteins between normal and cancerous prostate cells through changes in the ESIPT emission intensity. These results indicated that could distinguish individual prostate cancer cells from normal ones, as the changes in the ESIPT fluorescence intensity of could reflect the regulation in expression of the membrane proteins including zinc transporters. This recognition strategy of individual prostate cancer cells might contribute to early diagnosis techniques for prostate cancer.

Targeting the membrane-anchored serine protease testisin with a novel engineered anthrax toxin prodrug to kill tumor cells and reduce tumor burden

PubMed Central

Martin, Erik W.; Buzza, Marguerite S.; Driesbaugh, Kathryn H.; Liu, Shihui; Fortenberry, Yolanda M.; Leppla, Stephen H.; Antalis, Toni M.

2015-01-01

The membrane-anchored serine proteases are a unique group of trypsin-like serine proteases that are tethered to the cell surface via transmembrane domains or glycosyl-phosphatidylinositol-anchors. Overexpressed in tumors, with pro-tumorigenic properties, they are attractive targets for protease-activated prodrug-like anti-tumor therapies. Here, we sought to engineer anthrax toxin protective antigen (PrAg), which is proteolytically activated on the cell surface by the proprotein convertase furin to instead be activated by tumor cell-expressed membrane-anchored serine proteases to function as a tumoricidal agent. PrAg's native activation sequence was mutated to a sequence derived from protein C inhibitor (PCI) that can be cleaved by membrane-anchored serine proteases, to generate the mutant protein PrAg-PCIS. PrAg-PCIS was resistant to furin cleavage in vitro, yet cytotoxic to multiple human tumor cell lines when combined with FP59, a chimeric anthrax toxin lethal factor-Pseudomonas exotoxin fusion protein. Molecular analyses showed that PrAg-PCIS can be cleaved in vitro by several serine proteases including the membrane-anchored serine protease testisin, and mediates increased killing of testisin-expressing tumor cells. Treatment with PrAg-PCIS also potently attenuated the growth of testisin-expressing xenograft tumors in mice. The data indicates PrAg can be engineered to target tumor cell-expressed membrane-anchored serine proteases to function as a potent tumoricidal agent. PMID:26392335

Glucose transporter 3 (GLUT3) protein expression in human placenta across gestation

PubMed Central

Brown, Kelecia; Heller, Debra S.; Zamudio, Stacy; Illsley, Nicholas P.

2012-01-01

Conflicting information regarding expression of GLUT3 protein in the human placenta has been reported and the localization and pattern of expression of GLUT3 protein across gestation has not been clearly defined. The objective of this study was characterization of syncytial GLUT3 protein expression across gestation. We hypothesized that GLUT3 protein is present in the syncytial microvillous membrane and that its expression decreases over gestation. GLUT3 protein was measured in samples from a range of gestational ages (first to third trimester), with human brain and human bowel used as a positive and negative control respectively. As an additional measure of specificity, we transfected BeWo choriocarcinoma cells, a trophoblast cell line expressing GLUT3, with siRNA directed against GLUT3 and analyzed expression by Western blotting. GLUT3 was detected in the syncytiotrophoblast at all gestational ages by immunohistochemistry. Using Western blotting GLUT3 was detected as an integral membrane protein at a molecular weight of ~50kDa in microvillous membranes from all trimesters but not in syncytial basal membranes. The identity of the primary antibody target was confirmed by demonstrating that expression of the immunoblotting signal in GLUT3 siRNA-treated BeWo was decreased to 18 ± 6% (mean ± SEM) of that seen in cells transfected with a non-targeting siRNA. GLUT3 expression in microvillous membranes detected by Western blot decreased through the trimesters such that expression in the second trimester (wks 14–26) was 48 ± 7% of that in the first trimester and by the third trimester (wks 31–40) only 34 ± 10% of first trimester expression. In addition, glucose uptake into BeWo cells treated with GLUT3 siRNA was reduced to 60% of that measured in cells treated with the non-targeting siRNA. This suggests that GLUT3-mediated uptake comprises approximately 50% of glucose uptake into BeWo cells. These results confirm the hypothesis that GLUT3 is present in the syncytial microvillous membrane early in gestation and decreases thereafter, supporting the idea that GLUT3 is of greater importance for glucose uptake early in gestation. PMID:22000473

Targeting of GLUT1-GLUT5 chimeric proteins in the polarized cell line Caco-2.

PubMed

Inukai, K; Takata, K; Asano, T; Katagiri, H; Ishihara, H; Nakazaki, M; Fukushima, Y; Yazaki, Y; Kikuchi, M; Oka, Y

1997-04-01

Caco-2, a human differentiated intestinal epithelial cell line, is a promising model for investigating the mechanism of polarized targeting of apical and basolateral membrane proteins. We stably transfected rat GLUT5 cDNA and rabbit GLUT1 cDNA into Caco-2 cells with an expression vector. Immunohistochemical study revealed that the GLUT5 protein expressed was localized at apical membranes and that the GLUT1 expressed was present primarily in the basolateral membranes of cells grown on permeable support. Next, to investigate the domain responsible for determining apical vs. basolateral sorting in glucose transporters, we prepared several GLUT1-GLUT5 chimeric cDNAs and transfected them into Caco-2 cells. A GLUT1 [N terminus approximately sixth transmembrane domain (TM6)]-GLUT5 [intracellular loop (IL) approximately C terminus] chimera was observed exclusively at the apical membrane, while GLUT1 (N terminus approximately IL)-GLUT5 (TM7 approximately C terminus) and GLUT1 (N terminus approximately TM12)-GLUT5 (C-terminal domain) chimeras were observed mainly at the basolateral membrane, a localization similar to that of GLUT1. Moreover, using a recombinant adenovirus expression system, we expressed a GLUT5 (N terminus approximately TM6)-GLUT1(IL)-GLUT5(TM7 approximately C-terminus) chimera, which was observed at the basolateral membrane. Based on these results, the C-terminal domain does not determine isoform-specific targeting of GLUT1 and GLUT5. Rather, it is the intracellular loop in glucose transporters that appears to play a pivotal role in apical-basolateral sorting signals in Caco-2 cells.

STEAP: A prostate-specific cell-surface antigen highly expressed in human prostate tumors

PubMed Central

Hubert, Rene S.; Vivanco, Igor; Chen, Emily; Rastegar, Shiva; Leong, Kahan; Mitchell, Steve C.; Madraswala, Rashida; Zhou, Yanhong; Kuo, James; Raitano, Arthur B.; Jakobovits, Aya; Saffran, Douglas C.; Afar, Daniel E. H.

1999-01-01

In search of novel genes expressed in metastatic prostate cancer, we subtracted cDNA isolated from benign prostatic hypertrophic tissue from cDNA isolated from a prostate cancer xenograft model that mimics advanced disease. One novel gene that is highly expressed in advanced prostate cancer encodes a 339-amino acid protein with six potential membrane-spanning regions flanked by hydrophilic amino- and carboxyl-terminal domains. This structure suggests a potential function as a channel or transporter protein. This gene, named STEAP for six-transmembrane epithelial antigen of the prostate, is expressed predominantly in human prostate tissue and is up-regulated in multiple cancer cell lines, including prostate, bladder, colon, ovarian, and Ewing sarcoma. Immunohistochemical analysis of clinical specimens demonstrates significant STEAP expression at the cell–cell junctions of the secretory epithelium of prostate and prostate cancer cells. Little to no staining was detected at the plasma membranes of normal, nonprostate human tissues, except for bladder tissue, which expressed low levels of STEAP at the cell membrane. Protein analysis located STEAP at the cell surface of prostate-cancer cell lines. Our results support STEAP as a cell-surface tumor-antigen target for prostate cancer therapy and diagnostic imaging. PMID:10588738

The exposure of cancer cells to hyperthermia, iron oxide nanoparticles, and mitomycin C influences membrane multidrug resistance protein expression levels.

PubMed

Franke, Karolin; Kettering, Melanie; Lange, Kathleen; Kaiser, Werner A; Hilger, Ingrid

2013-01-01

The presence of multidrug resistance-associated protein (MRP) in cancer cells is known to be responsible for many therapeutic failures in current oncological treatments. Here, we show that the combination of different effectors like hyperthermia, iron oxide nanoparticles, and chemotherapeutics influences expression of MRP 1 and 3 in an adenocarcinoma cell line. BT-474 cells were treated with magnetic nanoparticles (MNP; 1.5 to 150 μg Fe/cm(2)) or mitomycin C (up to 1.5 μg/cm(2), 24 hours) in the presence or absence of hyperthermia (43°C, 15 to 120 minutes). Moreover, cells were also sequentially exposed to these effectors (MNP, hyperthermia, and mitomycin C). After cell harvesting, mRNA was extracted and analyzed via reverse transcription polymerase chain reaction. Additionally, membrane protein was isolated and analyzed via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. When cells were exposed to the effectors alone or to combinations thereof, no effects on MRP 1 and 3 mRNA expression were observed. In contrast, membrane protein expression was influenced in a selective manner. The effects on MRP 3 expression were less pronounced compared with MRP 1. Treatment with mitomycin C decreased MRP expression at high concentrations and hyperthermia intensified these effects. In contrast, the presence of MNP only increased MRP 1 and 3 expression, and hyperthermia reversed these effects. When combining hyperthermia, magnetic nanoparticles, and mitomycin C, no further suppression of MRP expression was observed in comparison with the respective dual treatment modalities. The different MRP 1 and 3 expression levels are not associated with de novo mRNA expression, but rather with an altered translocation of MRP 1 and 3 to the cell membrane as a result of reactive oxygen species production, and with shifting of intracellular MRP storage pools, changes in membrane fluidity, etc, at the protein level. Our results could be used to develop new treatment strategies by repressing mechanisms that actively export drugs from the target cell, thereby improving the therapeutic outcome in oncology.

The exposure of cancer cells to hyperthermia, iron oxide nanoparticles, and mitomycin C influences membrane multidrug resistance protein expression levels

PubMed Central

Franke, Karolin; Kettering, Melanie; Lange, Kathleen; Kaiser, Werner A; Hilger, Ingrid

2013-01-01

Purpose The presence of multidrug resistance-associated protein (MRP) in cancer cells is known to be responsible for many therapeutic failures in current oncological treatments. Here, we show that the combination of different effectors like hyperthermia, iron oxide nanoparticles, and chemotherapeutics influences expression of MRP 1 and 3 in an adenocarcinoma cell line. Methods BT-474 cells were treated with magnetic nanoparticles (MNP; 1.5 to 150 μg Fe/cm2) or mitomycin C (up to 1.5 μg/cm2, 24 hours) in the presence or absence of hyperthermia (43°C, 15 to 120 minutes). Moreover, cells were also sequentially exposed to these effectors (MNP, hyperthermia, and mitomycin C). After cell harvesting, mRNA was extracted and analyzed via reverse transcription polymerase chain reaction. Additionally, membrane protein was isolated and analyzed via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Results When cells were exposed to the effectors alone or to combinations thereof, no effects on MRP 1 and 3 mRNA expression were observed. In contrast, membrane protein expression was influenced in a selective manner. The effects on MRP 3 expression were less pronounced compared with MRP 1. Treatment with mitomycin C decreased MRP expression at high concentrations and hyperthermia intensified these effects. In contrast, the presence of MNP only increased MRP 1 and 3 expression, and hyperthermia reversed these effects. When combining hyperthermia, magnetic nanoparticles, and mitomycin C, no further suppression of MRP expression was observed in comparison with the respective dual treatment modalities. Discussion The different MRP 1 and 3 expression levels are not associated with de novo mRNA expression, but rather with an altered translocation of MRP 1 and 3 to the cell membrane as a result of reactive oxygen species production, and with shifting of intracellular MRP storage pools, changes in membrane fluidity, etc, at the protein level. Our results could be used to develop new treatment strategies by repressing mechanisms that actively export drugs from the target cell, thereby improving the therapeutic outcome in oncology. PMID:23378758

Characterisation of human tubular cell monolayers as a model of proximal tubular xenobiotic handling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Colin D.A.; Sayer, Rachel; Windass, Amy S.

2008-12-15

The aim of this study was to determine whether primary human tubular cell monolayers could provide a powerful tool with which to investigate the renal proximal tubular handling of xenobiotics. Human proximal and distal tubule/collecting duct cells were grown as monolayers on permeable filter supports. After 10 days in culture, proximal tubule cells remained differentiated and expressed a wide palette of transporters at the mRNA level including NaPi-IIa, SGLT1, SGLT2, OCT2, OCTN2, OAT1, OAT3, OAT4, MDR1, MRP2 and BCRP. At the protein level, the expression of a subset of transporters including NaPi-IIa, OAT1 and OAT3 was demonstrated using immunohistochemistry. Analysismore » of the expression of the ATP binding cassette efflux pumps MDR1, MRP2 and BCRP confirmed their apical membrane localisation. At the functional level, tubule cell monolayers retain the necessary machinery to mediate the net secretion of the prototypic substrates; PAH and creatinine. PAH secretion across the monolayer consisted of the uptake of PAH across the basolateral membrane by OAT1 and OAT3 and the apical exit of PAH by a probenecid and MK571-sensitive route consistent with actions of MRP2 or MRP4. Creatinine secretion was by OCT2-mediated uptake at the basolateral membrane and via MDR1 at the apical membrane. Functional expression of MDR1 and BCRP at the apical membrane was also demonstrated using a Hoechst 33342 dye. Similarly, measurement of calcein efflux demonstrated the functional expression of MRP2 at the apical membrane of cell monolayers. In conclusion, human tubular cell monolayers provide a powerful tool to investigate renal xenobiotic handling.« less

Inhibitory effect of calcium on non-heme iron absorption may be related to translocation of DMT-1 at the apical membrane of enterocytes.

PubMed

Thompson, Ben A V; Sharp, Paul A; Elliott, Ruan; Fairweather-Tait, Susan J

2010-07-28

Many studies show that calcium reduces iron absorption from single meals, but the underlying mechanism is not known. We tested the hypothesis that calcium alters the expression and/or functionality of iron transport proteins. Differentiated Caco-2 cells were treated with ferric ammonium citrate and calcium chloride, and ferritin, DMT-1, and ferroportin were quantified in whole-cell lysate and cell-membrane fractions. Calcium attenuated the iron-induced increase in cell ferritin levels in a dose-dependent manner; a significant decrease was seen at calcium concentrations of 1.25 and 2.5 mM but was only evident after a 16-24 h incubation period. Calcium and iron treatments decreased DMT-1 protein in Caco-2 cell membranes, although total DMT-1 in whole cell lysates was unchanged by either iron or calcium. No change was seen in ferroportin expression. Our data suggest that calcium reduces iron bioavailability by decreasing DMT-1 expression at the apical cell membrane, thereby downregulating iron transport into the cell.

Mistargeting of a truncated Na-K-2Cl cotransporter in epithelial cells.

PubMed

Koumangoye, Rainelli; Omer, Salma; Delpire, Eric

2018-05-02

We recently reported the case of a young patient with multi-system failure carrying a de novo mutation in SLC12A2, the gene encoding the Na-K-2Cl cotransporter-1. Heterologous expression studies in non-epithelial cells failed to demonstrate dominant-negative effects. In this study, we examined expression of the mutant cotransporter in epithelial cells. Using MDCK cells grown on glass coverslips, permeabilized support, and matrigel, we show that the fluorescently-tagged mutant cotransporter is expressed in cytoplasm and at the apical membrane and affects epithelium integrity. Expression of the mutant transporter at the apical membrane also results in the mislocalization of some of the wild-type transporter to the apical membrane. This mistargeting is specific to NKCC1 as the Na + /K + -ATPase remains localized on the basolateral membrane. To assess transporter localization in vivo, we created a mouse model using CRISPR/cas9 that reproduces the 11 bp deletion in exon 22 of Slc12a2. While the mice do not display an overt phenotype, we show that the colon and salivary gland expresses wild-type NKCC1 abundantly at the apical pole, confirming the data obtained in cultured epithelial cells. Enough cotransporter must remain, however, on the basolateral membrane to participate in saliva secretion, as no significant decrease in saliva production was observed in the mutant mice.

Development of Membrane-Bound GM-CSF and IL-18 as an Effective Tumor Vaccine

PubMed Central

Cheng, Ta-Chun; Chuang, Chih-Hung; Kao, Chien-Han; Hsieh, Yuan-Chin; Cheng, Kuang-Hung; Wang, Jaw-Yuan; Cheng, Chiu-Min; Chen, Chien-Shu; Cheng, Tian-Lu

2015-01-01

The development of effective adjuvant is the key factor to boost the immunogenicity of tumor cells as a tumor vaccine. In this study, we expressed membrane-bound granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-18 (IL-18) as adjuvants in tumor cells to stimulate immune response. B7 transmembrane domain fused GM-CSF and IL-18 was successfully expressed in the cell membrane and stimulated mouse splenocyte proliferation. Co-expression of GM-CSF and IL-18 reduced tumorigenesis (P<0.05) and enhanced tumor protective efficacy (P<0.05) significantly in comparison with GM-CSF alone. These results indicated that the combination of GM-CSF andIL-18 will enhance the immunogenicity of a cell-based anti-tumor vaccine. This membrane-bound approach can be applied to other cytokines for the development of novel vaccine strategies. PMID:26186692

The Leptospira outer membrane protein LipL32 induces tubulointerstitial nephritis-mediated gene expression in mouse proximal tubule cells.

PubMed

Yang, Chih-Wei; Wu, Mai-Szu; Pan, Ming-Jeng; Hsieh, Wang-Ju; Vandewalle, Alain; Huang, Chiu-Ching

2002-08-01

Tubulointerstitial nephritis is a main renal manifestation caused by pathogenic leptospira that accumulate mostly in the proximal tubules, thereby inducing tubular injury and tubulointerstitial nephritis. To elucidate the role of leptospira outer membrane proteins in tubulointerstitial nephritis, outer membrane proteins from pathogenic Leptospira shermani and nonpathogenic Leptospira patoc extracted by Triton X-114 were administered to cultured mouse proximal tubule cells. A dose-dependent increase of monocyte chemoattractant protein-1 (MCP-1), RANTES, nitrite, and tumor necrosis factor-alpha (TNF-alpha) in the culture supernatant was observed 48 h after incubating Leptospira shermani outer membrane proteins with mouse proximal tubule cells. RT competitive-PCR experiments showed that Leptospira shermani outer membrane proteins (0.2 microg/ml) increased the expression of MCP-1, nitric oxide synthase (iNOS), RANTES, and TNF-alpha mRNA by 3.0-, 9.4-, 2.5-, and 2.5-fold, respectively, when compared with untreated cells. Outer membrane proteins extract from avirulent Leptospira patoc did not induce significant effects. The pathogenic outer membrane proteins extract contain a major component of a 32-kD lipoprotein (LipL32), which is absent in the nonpathogenic leptospira outer membrane. An antibody raised against LipL32 prevented the stimulatory effect of Leptospira shermani outer membrane proteins extract on MCP-1 and iNOS mRNA expression in cultured proximal tubule cells, whereas recombinant LipL32 significantly stimulated the expression of MCP-1 and iNOS mRNAs and augmented nuclear binding of nuclear factor-kappaB (NF-kappaB) and AP-1 transcription factors in proximal tubule cells. An antibody raised against LipL32 also blunted the effects induced by the recombinant LipL32. This study demonstrates that LipL32 is a major component of pathogenic leptospira outer membrane proteins involved in the pathogenesis of tubulointerstitial nephritis.

PTK6 activation at the membrane regulates epithelial-mesenchymal transition in prostate cancer.

PubMed

Zheng, Yu; Wang, Zebin; Bie, Wenjun; Brauer, Patrick M; Perez White, Bethany E; Li, Jing; Nogueira, Veronique; Raychaudhuri, Pradip; Hay, Nissim; Tonetti, Debra A; Macias, Virgilia; Kajdacsy-Balla, André; Tyner, Angela L

2013-09-01

The intracellular tyrosine kinase protein tyrosine kinase 6 (PTK6) lacks a membrane-targeting SH4 domain and localizes to the nuclei of normal prostate epithelial cells. However, PTK6 translocates from the nucleus to the cytoplasm in human prostate tumor cells. Here, we show that while PTK6 is located primarily within the cytoplasm, the pool of active PTK6 in prostate cancer cells localizes to membranes. Ectopic expression of membrane-targeted active PTK6 promoted epithelial-mesenchymal transition in part by enhancing activation of AKT, thereby stimulating cancer cell migration and metastases in xenograft models of prostate cancer. Conversely, siRNA-mediated silencing of endogenous PTK6 promoted an epithelial phenotype and impaired tumor xenograft growth. In mice, PTEN deficiency caused endogenous active PTK6 to localize at membranes in association with decreased E-cadherin expression. Active PTK6 was detected at membranes in some high-grade human prostate tumors, and PTK6 and E-cadherin expression levels were inversely correlated in human prostate cancers. In addition, high levels of PTK6 expression predicted poor prognosis in patients with prostate cancer. Our findings reveal novel functions for PTK6 in the pathophysiology of prostate cancer, and they define this kinase as a candidate therapeutic target. Cancer Res; 73(17); 5426-37. ©2013 AACR.

Caveolin-1 is a negative regulator of caveolae-mediated endocytosis to the endoplasmic reticulum.

PubMed

Le, Phuong U; Guay, Ginette; Altschuler, Yoram; Nabi, Ivan R

2002-02-01

Caveolae are flask-shaped invaginations at the plasma membrane that constitute a subclass of detergent-resistant membrane domains enriched in cholesterol and sphingolipids and that express caveolin, a caveolar coat protein. Autocrine motility factor receptor (AMF-R) is stably localized to caveolae, and the cholesterol extracting reagent, methyl-beta-cyclodextrin, inhibits its internalization to the endoplasmic reticulum implicating caveolae in this distinct receptor-mediated endocytic pathway. Curiously, the rate of methyl-beta-cyclodextrin-sensitive endocytosis of AMF-R to the endoplasmic reticulum is increased in ras- and abl-transformed NIH-3T3 cells that express significantly reduced levels of caveolin and few caveolae. Overexpression of the dynamin K44A dominant negative mutant via an adenovirus expression system induces caveolar invaginations sensitive to methyl-beta-cyclodextrin extraction in the transformed cells without increasing caveolin expression. Dynamin K44A expression further inhibits AMF-R-mediated endocytosis to the endoplasmic reticulum in untransformed and transformed NIH-3T3 cells. Adenoviral expression of caveolin-1 also induces caveolae in the transformed NIH-3T3 cells and reduces AMF-R-mediated endocytosis to the endoplasmic reticulum to levels observed in untransformed NIH-3T3 cells. Cholesterol-rich detergent-resistant membrane domains or glycolipid rafts therefore invaginate independently of caveolin-1 expression to form endocytosis-competent caveolar vesicles via rapid dynamin-dependent detachment from the plasma membrane. Caveolin-1 stabilizes the plasma membrane association of caveolae and thereby acts as a negative regulator of the caveolae-mediated endocytosis of AMF-R to the endoplasmic reticulum.

Global analysis of glycoproteins identifies markers of endotoxin tolerant monocytes and GPR84 as a modulator of TNFα expression.

PubMed

Müller, Mario M; Lehmann, Roland; Klassert, Tilman E; Reifenstein, Stella; Conrad, Theresia; Moore, Christoph; Kuhn, Anna; Behnert, Andrea; Guthke, Reinhard; Driesch, Dominik; Slevogt, Hortense

2017-04-12

Exposure of human monocytes to lipopolysaccharide (LPS) induces a temporary insensitivity to subsequent LPS challenges, a cellular state called endotoxin tolerance. In this study, we investigated the LPS-induced global glycoprotein expression changes of tolerant human monocytes and THP-1 cells to identify markers and glycoprotein targets capable to modulate the immunosuppressive state. Using hydrazide chemistry and LC-MS/MS analysis, we analyzed glycoprotein expression changes during a 48 h LPS time course. The cellular snapshots at different time points identified 1491 glycoproteins expressed by monocytes and THP-1 cells. Label-free quantitative analysis revealed transient or long-lasting LPS-induced expression changes of secreted or membrane-anchored glycoproteins derived from intracellular membrane coated organelles or from the plasma membrane. Monocytes and THP-1 cells demonstrated marked differences in glycoproteins differentially expressed in the tolerant state. Among the shared differentially expressed glycoproteins G protein-coupled receptor 84 (GPR84) was identified as being capable of modulating pro-inflammatory TNFα mRNA expression in the tolerant cell state when activated with its ligand Decanoic acid.

Hydroxychloroquine inhibits CD154 expression in CD4+ T lymphocytes of systemic lupus erythematosus through NFAT, but not STAT5, signaling.

PubMed

Wu, Shu-Fen; Chang, Chia-Bin; Hsu, Jui-Mei; Lu, Ming-Chi; Lai, Ning-Sheng; Li, Chin; Tung, Chien-Hsueh

2017-08-09

Overexpression of membranous CD154 in T lymphocytes has been found previously in systemic lupus erythematosus (SLE). Because hydroxychloroquine (HCQ) has been used frequently in the treatment of lupus, we sought to identify the effects of HCQ on CD154 and a possibly regulatory mechanism. CD4 + T cells were isolated from the blood of lupus patients. After stimulation with ionomycin or IL-15 and various concentrations of HCQ, expression of membranous CD154 and NFAT and STAT5 signaling were assessed. HCQ treatment had significant dose-dependent suppressive effects on membranous CD154 expression in ionomycin-activated T cells from lupus patients. Furthermore, HCQ inhibited intracellular sustained calcium storage release, and attenuated the nuclear translocation of NFATc2 and the expression of NFATc1. However, CD154 expressed through IL-15-mediated STAT5 signaling was not inhibited by HCQ treatment. HCQ inhibited NFAT signaling in activated T cells and blocked the expression of membranous CD154, but not STAT5 signaling. These findings provide a mechanistic insight into SLE in HCQ treatment.

Myeloid-Related Protein-14/MRP-14/S100A9/Calgranulin B is Associated with Inflammation in Proliferative Diabetic Retinopathy.

PubMed

Abu El-Asrar, Ahmed M; Alam, Kaiser; Siddiquei, Mohammad M; Van den Eynde, Kathleen; Mohammad, Ghulam; De Hertogh, Gert; Opdenakker, Ghislain

2018-01-01

To investigate the expression of the leukocyte proteins myeloid-related protein (MRP)-8 and MRP-14 in proliferative diabetic retinopathy (PDR) and the effect of MRP-8/MRP-14 (calprotectin) heterodimer on induction of proinflammatory factors in human retinal microvascular endothelial cells (HRMEC). Epiretinal membranes from 20 patients with PDR and 10 patients with proliferative vitreoretinopathy (PVR), vitreous fluid samples from PDR and non-diabetic subjects and HRMEC were studied by immunohistochemistry and Western blot analysis. MRP-14 expression was localized in endothelial cells, leukocytes and myofibroblasts in all PDR membranes. MRP-8 expression was limited to intravascular leukocytes in 42% of the studied membranes. In PVR membranes, MRP-14 was expressed in leukocytes and myofibroblasts, whereas MRP-8 immunoreactivity was limited to leukocytes. MRP-14 was significantly upregulated in vitreous from PDR patients. MRP-8/MRP-14 (calprotectin) increased expression of intercellular adhesion molecule-1, but attenuated vascular cell adhesion molecule-1 expression in HRMEC. Increased MRP-14 levels are associated with inflammation in PDR.

Antigen sensitivity of CD22-specific chimeric T cell receptors is modulated by target epitope distance from the cell membrane

PubMed Central

James, Scott E.; Greenberg, Philip D.; Jensen, Michael C.; Lin, Yukang; Wang, Jinjuan; Till, Brian G.; Raubitschek, Andrew A.; Forman, Stephen J.; Press, Oliver W.

2008-01-01

We have targeted CD22 as a novel tumor-associated antigen for recognition by human CTL genetically modified to express chimeric T cell receptors (cTCR) recognizing this surface molecule. CD22-specifc cTCR targeting different epitopes of the CD22 molecule promoted efficient lysis of target cells expressing high levels of CD22 with a maximum lytic potential that appeared to decrease as the distance of the target epitope from the target cell membrane increased. Targeting membrane-distal CD22 epitopes with cTCR+ CTL revealed defects in both degranulation and lytic granule targeting. CD22-specific cTCR+ CTL exhibited lower levels of maximum lysis and lower antigen sensitivity than CTL targeting CD20, which has a shorter extracellular domain than CD22. This diminished sensitivity was not a result of reduced avidity of antigen engagement, but instead reflected weaker signaling per triggered cTCR molecule when targeting membrane-distal epitopes of CD22. Both of these parameters were restored by targeting a ligand expressing the same epitope but constructed as a truncated CD22 molecule to approximate the length of a TCR:pMHC complex. The reduced sensitivity of CD22-specific cTCR+ CTL for antigen-induced triggering of effector functions has potential therapeutic applications, as such cells selectively lysed B cell lymphoma lines expressing high levels of CD22 but demonstrated minimal activity against autologous normal B cells, which express lower levels of CD22. Thus, our results demonstrate that cTCR signal strength – and consequently antigen sensitivity – can be modulated by differential choice of target epitopes with respect to distance from the cell membrane, allowing discrimination between targets with disparate antigen density. PMID:18453625

PTPN6 regulates the cell-surface expression of TRPM4 channels in HEK293 cells.

PubMed

Lee, Dong Kun; Park, Jung Yeon; Yoo, Jae Cheal; Byun, Eun Hye; Bae, Yeon-Ju; Lee, Young-Sun; Park, Nammi; Kang, Dawon; Han, Jaehee; Park, Jae Yong; Hwang, Eunmi; Hong, Seong-Geun

2018-06-21

Transient receptor-potential, cation channel, subfamily M, member 4 (TRPM4) channels regulate a variety of physiological and pathological processes; however, their roles as functional channels under diverse conditions remain unclear. In this study, cytosolic protein tyrosine phosphatase non-receptor type 6 (PTPN6) interacted with TRPM4 channels. We confirmed their interaction by performing co-immunoprecipitation (Co-IP) assays following heterologous PTPN6 and TRPM4 channel expression in HEK293 cells. Furthermore, biomolecular fluorescence complementation (BiFC) image analysis confirmed TRPM4-PTPN6 binding. In addition, immunoblotting and Co-IP analyses revealed that TRPM4 expression significantly decreased in the membrane fraction of cells after PTPN6 was silenced with a specific short-hairpin RNA (shRNA-PTPN6). In agreement, TRPM4-induced changes in whole-cell currents were not detected in PTPN6-silenced HEK cells, in contrast to cells transfected with a scrambled RNA (scRNA) or in naïve HEK cells. These data suggest that PTPN6 inhibits TRPM4 channel activity by disrupting TRPM4 expression. Furthermore, TRPM4 channels were expressed in the membrane of naïve cells and scRNA transfectants, but not in those of PTPN6-silenced cells. These results indicated that PTPN6 is critically associated with TRPM4 trafficking. This role of PTPN6 in TRPM4 membrane localization was also demonstrated in HeLa cells. TRPM4 overexpression significantly enhanced cell proliferation in untreated HeLa cells, but not in HeLa cells with silenced PTPN6 expression. These findings indicate that PTPN6-dependent TRPM4 expression and trafficking to the plasma membrane is critical for cell proliferation in both HEK293 and HeLa cells. Therefore, PTPN6 is a novel therapeutic target for treating pathologic diseases involving TRPM4.

Elucidating the role of Cyclooxygenase-2 in the pathogenesis of oral lichen planus - an immunohistochemical study with supportive histochemical analysis.

PubMed

Singh, Pratyush; Grover, Jasleen; Byatnal, Aditi Amit; Guddattu, Vasudeva; Radhakrishnan, Raghu; Solomon, Monica Charlotte

2017-05-01

Oral lichen planus (OLP) is a chronic, inflammatory disorder that affects the oral mucous membrane. During an inflammatory response, several chemokines and cytokines are released by the cells of the immune system. Activation of MMPs, along with mast cell-derived chymase and tryptase, degrades the basement membrane structural proteins, resulting in basement membrane breaks. To investigate the association between the COX-2 expressions, presence of intact or degranulating mast cells within the connective tissue and the extent of basement membrane discontinuity in OLP cases. This study included a total of 50 formalin-fixed paraffin-embedded specimens (FFPE) of histologically confirmed cases of idiopathic oral lichen planus. A retrospective cross-sectional analysis was carried out by immunohistochemistry to study the epithelial expression of COX-2 and by the use of special stains such as toluidine blue and periodic acid-Schiff (PAS) to study the mast cell count and basement membrane changes in the oral mucosal tissue, respectively. There was a significant (P = 0.03) association between the COX-2 expressions and mast cell count. As the intensity of COX-2 expression increased from mild to moderate or severe, the number of mast cell count almost doubled. Interaction between upregulation of COX-2, mast cell and basement membrane sets a vicious cycle which relates to the chronic nature of the disease. Inhibitors of COX-2 may reduce the inflammatory process preceding the immune dysregulation in OLP. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Proteolytic Enzymes Clustered in Specialized Plasma-Membrane Domains Drive Endothelial Cells’ Migration

PubMed Central

Salamone, Monica; Carfì Pavia, Francesco

2016-01-01

In vitro cultured endothelial cells forming a continuous monolayer establish stable cell-cell contacts and acquire a “resting” phenotype; on the other hand, when growing in sparse conditions these cells acquire a migratory phenotype and invade the empty area of the culture. Culturing cells in different conditions, we compared expression and clustering of proteolytic enzymes in cells having migratory versus stationary behavior. In order to observe resting and migrating cells in the same microscopic field, a continuous cell monolayer was wounded. Increased expression of proteolytic enzymes was evident in cell membranes of migrating cells especially at sprouting sites and in shed membrane vesicles. Gelatin zymography and western blotting analyses confirmed that in migrating cells, expression of membrane-bound and of vesicle-associated proteolytic enzymes are increased. The enzymes concerned include MMP-2, MMP-9, MT1-MMP, seprase, DPP4 (DiPeptidyl Peptidase 4) and uPA. Shed membrane vesicles were shown to exert degradative activity on ECM components and produce substrates facilitating cell migration. Vesicles shed by migrating cells degraded ECM components at an increased rate; as a result their effect on cell migration was amplified. Inhibiting either Matrix Metallo Proteases (MMPs) or Serine Integral Membrane Peptidases (SIMPs) caused a decrease in the stimulatory effect of vesicles, inhibiting the spontaneous migratory activity of cells; a similar result was also obtained when a monoclonal antibody acting on DPP4 was tested. We conclude that proteolytic enzymes have a synergistic stimulatory effect on cell migration and that their clustering probably facilitates the proteolytic activation cascades needed to produce maximal degradative activity on cell substrates during the angiogenic process. PMID:27152413

Differential plasma membrane targeting of voltage-dependent calcium channel subunits expressed in a polarized epithelial cell line

PubMed Central

Brice, Nicola L; Dolphin, Annette C

1999-01-01

Voltage-dependent calcium channels (VDCCs) show a highly non-uniform distribution in many cell types, including neurons and other polarized secretory cells. We have examined whether this can be mimicked in a polarized epithelial cell line (Madin-Darby canine kidney), which has been used extensively to study the targeting of proteins. We expressed the VDCC α1A, α1B or α1C subunits either alone or in combination with accessory subunits α2-δ and the different β subunits, and examined their localization immunocytochemically. An α1 subunit was only targeted to the plasma membrane if co-expressed with the accessory subunits. The combination α1C/α2-δ and all β subunits was always localized predominantly to the basolateral membrane. It has been suggested that this is equivalent to somatodendritic targeting in neurons. In contrast, the α1B subunit was expressed at the apical membrane with all the accessory subunit combinations, by 24 h after microinjection. This membrane destination shows some parallels with axonal targeting in neurons. The α1A subunit was consistently observed at the apical membrane in the combinations α1A/α2-δ/β1b or β4. In contrast, when co-expressed with α2-δ/β2a, α1A was clearly targeted to the basolateral membrane. In conclusion, the VDCC α1 subunit appears to be the primary determinant for targeting the VDCC complex, but the β subunit can modify this destination, particularly for α1A. PMID:10066897

[Distribution diversity of integrins and calcium channels on major human and mouse host cells of Leptospira species].

PubMed

Li, Cheng-xue; Zhao, Xin; Qian, Jing; Yan, Jie

2012-07-01

To determine the distribution of integrins and calcium channels on major human and mouse host cells of Leptospira species. The expression of β1, β2 and β3 integrins was detected with immunofluorescence assay on the surface of human monocyte line THP-1, mouse mononuclear-macrophage-like cell line J774A.1, human vascular endothelial cell line HUVEC, mouse vascular endothelial cell EOMA, human hepatocyte line L-02, mouse hepatocyte line Hepa1-6, human renal tubular epithelial cell line HEK-293, mouse glomerular membrane epithelial cell line SV40-MES13, mouse collagen blast line NIH/3T3, human and mouse platelets. The distribution of voltage gate control calcium channels Cav3.1, Cav3.2, Cav3.3 and Cav2.3, and receptor gate calcium channels P(2)X(1), P(2)2X(2), P(2)X(3), P(2)X(4), P(2)X(5), P(2)X(6) and P(2)X(7) were determined with Western blot assay. β1 integrin proteins were positively expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, L-02, Hepa1-6 and HEK-239 cells as well as human and mouse platelets. β2 integrin proteins were expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, and NIH/3T3 cells. β3 integrin proteins were expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, Hepa1-6, HEK-239 and NIH/3T3 cells as well as human and mouse platelets. P(2)X(1) receptor gate calcium channel was expressed on the membrane surface of human and mouse platelets, while P(2)X(5) receptor gate calcium channel was expressed on the membrane surface of J774A.1, THP-1, L-02, Hepa1-6, HEK-239 and HUVEC cells. However, the other calcium channels were not detected on the tested cell lines or platelets. There is a large distribution diversity of integrins and calcium channel proteins on the major human and mouse host cells of Leptospira species, which may be associated with the differences of leptospira-induced injury in different host cells.

EphA2 Is a Potential Player of Malignant Cellular Behavior in Non-Metastatic Renal Cell Carcinoma Cells but Not in Metastatic Renal Cell Carcinoma Cells.

PubMed

Cho, Min Chul; Cho, Sung Yong; Yoon, Cheol Yong; Lee, Seung Bae; Kwak, Cheol; Kim, Hyeon Hoe; Jeong, Hyeon

2015-01-01

To investigate the role of EphA2 in malignant cellular behavior in renal cell carcinoma (RCC) cells and whether FAK/RhoA signaling can act as downstream effectors of EphA2 on RCC cells. Expression of EphA2 protein in non-metastatic RCC (Caki-2 and A498), metastatic RCC cells (Caki-1 and ACHN), HEK-293 cells and prostate cancer cells (PC-3 and DU-145; positive controls of EphA2 expression) was evaluated by Western blot. Changes in mRNA or protein expression of EphA2, FAK or membrane-bound RhoA following EphA2, FAK or RhoA small interfering RNA (siRNA) transfection were determined by reverse transcription polymerase chain reaction or Western blot. The effect of siRNA treatment on cellular viability, apoptosis and invasion was analyzed by cell counting kit-8, Annexin-V and modified Matrigel-Boyden assays, respectively. In all RCC cell lines, the expression of EphA2 protein was detectable at variable levels; however, in HEK-293 cells, EphA2 expression was very low. Treatment with EphA2 siRNA significantly reduced the expression of EphA2 mRNA and protein in all RCC cell lines. For non-metastatic RCC cells (Caki-2 and A498) but not metastatic RCC cells (Caki-1 and ACHN), cellular viability, invasiveness, resistance to apoptosis, expression of membrane-bound RhoA protein and FAK phosphorylation were significantly decreased in EphA2 siRNA-treated cells compared to the control. In non-metastatic RCC cells, FAK siRNA significantly attenuated the invasiveness, resistance to apoptosis, as well as expression of membrane-bound RhoA protein without changing protein expression of EphA2. RhoA siRNA significantly decreased the malignant cellular behavior and expression of membrane-bound RhoA protein without changing EphA2 protein expression or FAK phosphorylation. Our data provide the first functional evidence that the EphA2/FAK/RhoA signaling pathway plays a critical role in the malignant cellular behavior of RCC and appears to be functional particularly in the early stage of malignant progression of non-metastatic RCC.

The expression of the class 1 glucose transporter isoforms in human embryonic stem cells, and the potential use of GLUT2 as a marker for pancreatic progenitor enrichment.

PubMed

Segev, Hana; Fishman, Betina; Schulman, Rita; Itskovitz-Eldor, Joseph

2012-07-01

Even before the first appearance of the developing pancreas, glucose is the major substrate in the growing embryo. The transport of glucose across cell membranes is facilitated by a family of membranal glucose transporters (GLUT). We analyzed changes in expression of class 1 glucose transporters (GLUT1-4) during human embryonic stem cell (hESC) and human induced pluripotent stem cell (hiPSC) differentiation, from undifferentiated cells to 28-day-old embryoid bodies (EBs). We also examined the potential use of GLUT2 as a marker for differentiating pancreatic progenitor cells. Using quantitative real time polymerase chain reaction (qPCR), western blot, and immunofluorescence, we observed enhanced expression of GLUT1 and GLUT2 during differentiation, but only minor change in GLUT3 expression. GLUT4 expression was found to be very low both at the RNA and in the protein levels. Expression of the early pancreatic transcription factor, pancreatic duodenal homeobox gene 1 (PDX1), correlated with GLUT2 expression, suggesting the potential use of GLUT2 as a surface marker for tracking pancreatic precursor cells. After sorting EBs according to their membranal GLUT2 expression, GLUT2 and PDX1 expression were found elevated, as was expression of other endodermal markers such as PAX4, NGN3, CXCR4, and SOX17. This simple method may be used to differentiate embryonic stem cells and to isolate from them, using GLUT2 as a surface marker, an enriched pancreatic progenitor cell population in order to achieve insulin-producing cells. The sorted GLUT2 cells may potentially be used in the future as insulin-producing cells for beta cell therapies.

Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

PubMed Central

Ding, Xue-feng; Wu, Yan; Qu, Wen-rui; Fan, Ming; Zhao, Yong-qi

2018-01-01

Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine (20 and 40 mM) and irradiated them with 50 mW/cm2 microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation. PMID:29623929

Annexin A2 in Proliferative Vitreoretinopathy

DTIC Science & Technology

2017-10-01

cells , leading to formation of an epiretinal membrane, retinal detachment, and loss of vision. At present, there are no reliable means of...type versus annexin A2- deficient mice, [2] define the role of A2 in the function of activated macrophages and RPE cells in PVR, and [3] examine the...expression is needed in both macrophages and RPE cells , and that A2 is extensively expressed within cells of epiretinal membranes in human PVR. Our

[Extranodal nasal type NK/T-cell lymphoma: the expression of Epstein-Barr virus latent membrane protein 1 and its significance of prognosis].

PubMed

Zhao, Sha; Liu, Wei-ping; Zhang, Wen-yan; Li, Gan-di

2005-05-01

To investigate the expression and prognostic significance of Epstein-Barr virus latent membrane protein 1 in extranodal nasal type NK/T-cell lymphoma in the Chengdu area. The expression of latent membrane protein-1 (LMP1) was detected by immunohistochemistry (IHC) and DNA-PCR in 67 cases of extranodal nasal type NK/T-cell lymphoma, and the differences in survival rate between positive and negative expression groups of LMP1-protien and LMP1-DNA were analyzed respectively. Ten (14.93%) cases were positive at LMP1-protein level, and fifty-six (83.58%) were positive at LMP1-DNA level. The total expression rate of LMP1 was 83.58%. No statistically significant difference was observed between the expression of LMP1 and prognosis (P = 0.678) and between the expression of LMP1-DNA and prognosis (P = 0.943). LMP1 was shown to be closely associated with extranodal nasal type NK/T-cell lymphoma in Chengdu. The expression rate of LMP1 at protein level was different from that at DNA level. No relationship was found between the prognosis and the LMP1 expression in extranodal nasal type NK/T-cell lymphoma.

[Cloning and characterization of genes differentially expressed in human dental pulp cells and gingival fibroblasts].

PubMed

Wang, Zhong-dong; Wu, Ji-nan; Zhou, Lin; Ling, Jun-qi; Guo, Xi-min; Xiao, Ming-zhen; Zhu, Feng; Pu, Qin; Chai, Yu-bo; Zhao, Zhong-liang

2007-02-01

To study the biological properties of human dental pulp cells (HDPC) by cloning and analysis of genes differentially expressed in HDPC in comparison with human gingival fibroblasts (HGF). HDPC and HGF were cultured and identified by immunocytochemistry. HPDC and HGF subtractive cDNA library was established by PCR-based modified subtractive hybridization, genes differentially expressed by HPDC were cloned, sequenced and compared to find homogeneous sequence in GenBank by BLAST. Cloning and sequencing analysis indicate 12 genes differentially expressed were obtained, in which two were unknown genes. Among the 10 known genes, 4 were related to signal transduction, 2 were related to trans-membrane transportation (both cell membrane and nuclear membrane), and 2 were related to RNA splicing mechanisms. The biological properties of HPDC are determined by the differential expression of some genes and the growth and differentiation of HPDC are associated to the dynamic protein synthesis and secretion activities of the cell.

Hierarchy of stroma-derived factors in supporting growth of stroma-dependent hemopoietic cells: membrane-bound SCF is sufficient to confer stroma competence to epithelial cells.

PubMed

Friel, Jutta; Itoh, Katsuhiko; Bergholz, Ulla; Jücker, Manfred; Stocking, Carol; Harrison, Paul; Ostertag, Wolfram

2002-03-01

Hemopoiesis takes place in a microenvironment where hemopoietic cells are closely associated with stroma by various interactions. Stroma coregulates the proliferation and differentiation of hemopoietic cells. Stroma-hemopoietic-cell contact can be supported by locally produced membrane associated growth factors. The stroma derived growth factor, stem cell factor (SCF) is important in hemopoiesis. We examined the different biological interactions of membrane bound and soluble SCF with human hemopoietic cells expressing the SCF receptor, c-kit. To analyze the function of the SCF isoforms in inducing the proliferation of hemopoietic TF1 or Cord blood (CB) CD34+ cells we used stroma cell lines that differ in their presentation of no SCF, membrane SCF, or soluble SCF. We established a new coculture system using an epithelial cell line that excludes potential interfering effects with other known stroma encoded hemopoietic growth factors. We show that soluble SCF, in absence of membrane-bound SCF, inhibits long term clonal growth of primary or established CD34+ hemopoietic cells, whereas membrane-inserted SCF "dominantly" induces long term proliferation of these cells. We demonstrate a hierarchy of these SCF isoforms in the interaction of stroma with hemopoietic TF1 cells. Membrane-bound SCF is "dominant" over soluble SCF, whereas soluble SCF acts epistatically in interacting with hemopoietic cells compared with other stroma derived factors present in SCF deficient stroma. A hierarchy of stroma cell lines can be arranged according to their presentation of membrane SCF or soluble SCF. In our model system, membrane-bound SCF expression is sufficient to confer stroma properties to an epithelial cell line but soluble SCF does not.

Evidence of femtosecond-laser pulse induced cell membrane nanosurgery

NASA Astrophysics Data System (ADS)

Katchinskiy, Nir; Godbout, Roseline; Elezzabi, Abdulhakem Y.

2017-02-01

The mechanism of femtosecond laser nanosurgical attachment is investigated in the following article. Using sub-10 femtosecond laser pulses with 800 nm central wavelength were used to attach retinoblastoma cells. During the attachment process the cell membrane phospholipid bilayers hemifuse into one shared phospholipid bilayer, at the location of attachment. Transmission electron microscopy was used in order to verify the above hypothesis. Based on the imaging results, it was concluded that the two cell membrane coalesce to form one single shared membrane. The technique of cell-cell attachment via femtosecond laser pulses could potentially serve as a platform for precise cell membrane manipulation. Manipulation of the cellular membrane is valuable for studying diseases such as cancer; where the expression level of plasma proteins on the cell membrane is altered.

Use of Lentiviral Particles As a Cell Membrane-Based mFasL Delivery System for In Vivo Treatment of Inflammatory Arthritis.

PubMed

Rodríguez-Frade, José M; Guedán, Anabel; Lucas, Pilar; Martínez-Muñoz, Laura; Villares, Ricardo; Criado, Gabriel; Balomenos, Dimitri; Reyburn, Hugh T; Mellado, Mario

2017-01-01

During budding, lentiviral particles (LVP) incorporate cell membrane proteins in the viral envelope. We explored the possibility of harnessing this process to generate LVP-expressing membrane proteins of therapeutic interest and studied the potential of these tools to treat different pathologies. Fas-mediated apoptosis is central to the maintenance of T cell homeostasis and prevention of autoimmune processes. We prepared LVP that express murine FasL on their surface. Our data indicate that mFasL-bearing LVP induce caspase 3 and 9 processing, cytochrome C release, and significantly more cell death than control LVP in vitro . This cytotoxicity is blocked by the caspase inhibitor Z-VAD. Analysis of the application of these reagents for the treatment of inflammatory arthritis in vivo suggests that FasL-expressing LVP could be useful for therapy in autoimmune diseases such as rheumatoid arthritis, where there is an excess of Fas-expressing activated T cells in the joint. LVP could be a vehicle not only for mFasL but also for other membrane-bound proteins that maintain their native conformation and might mediate biological activities.

Synthesis and deposition of basement membrane proteins by primary brain capillary endothelial cells in a murine model of the blood-brain barrier.

PubMed

Thomsen, Maj Schneider; Birkelund, Svend; Burkhart, Annette; Stensballe, Allan; Moos, Torben

2017-03-01

The brain vascular basement membrane is important for both blood-brain barrier (BBB) development, stability, and barrier integrity and the contribution hereto from brain capillary endothelial cells (BCECs), pericytes, and astrocytes of the BBB is probably significant. The aim of this study was to analyse four different in vitro models of the murine BBB for expression and possible secretion of major basement membrane proteins from murine BCECs (mBCECs). mBCECs, pericytes and glial cells (mainly astrocytes and microglia) were prepared from brains of C57BL/6 mice. The mBCECs were grown as monoculture, in co-culture with pericytes or mixed glial cells, or as a triple-culture with both pericytes and mixed glial cells. The integrity of the BBB models was validated by measures of transendothelial electrical resistance (TEER) and passive permeability to mannitol. The expression of basement membrane proteins was analysed using RT-qPCR, mass spectrometry and immunocytochemistry. Co-culturing mBCECs with pericytes, mixed glial cells, or both significantly increased the TEER compared to the monoculture, and a low passive permeability was correlated with high TEER. The mBCECs expressed all major basement membrane proteins such as laminin-411, laminin-511, collagen [α1(IV)] 2 α2(IV), agrin, perlecan, and nidogen 1 and 2 in vitro. Increased expression of the laminin α5 subunit correlated with the addition of BBB-inducing factors (hydrocortisone, Ro 20-1724, and pCPT-cAMP), whereas increased expression of collagen IV α1 primarily correlated with increased levels of cAMP. In conclusion, BCECs cultured in vitro coherently form a BBB and express basement membrane proteins as a feature of maturation. Cover Image for this issue: doi: 10.1111/jnc.13789. © 2016 International Society for Neurochemistry.

A cell-penetrating peptide analogue, P7, exerts antimicrobial activity against Escherichia coli ATCC25922 via penetrating cell membrane and targeting intracellular DNA.

PubMed

Li, Lirong; Shi, Yonghui; Cheng, Xiangrong; Xia, Shufang; Cheserek, Maureen Jepkorir; Le, Guowei

2015-01-01

The antibacterial activities and mechanism of a new P7 were investigated in this study. P7 showed antimicrobial activities against five harmful microorganisms which contaminate and spoil food (MIC=4-32 μM). Flow cytometry and scanning electron microscopy analyses demonstrated that P7 induced pore-formation on the cell surface and led to morphological changes but did not lyse cell. Confocal fluorescence microscopic observations and flow cytometry analysis expressed that P7 could penetrate the Escherichia coli cell membrane and accumulate in the cytoplasm. Moreover, P7 possessed a strong DNA binding affinity. Further cell cycle analysis and change in gene expression analysis suggested that P7 induced a decreased expression in the genes involved in DNA replication. Up-regulated expression genes encoding DNA damage repair. This study suggests that P7 could be applied as a candidate for the development of new food preservatives as it exerts its antibacterial activities by penetrating cell membranes and targets intracellular DNA. Copyright © 2014 Elsevier Ltd. All rights reserved.

Expression of the SNARE Protein SNAP-23 Is Essential for Cell Survival

PubMed Central

Kaul, Sunil; Mittal, Sharad K.; Feigenbaum, Lionel; Kruhlak, Michael J.; Roche, Paul A.

2015-01-01

Members of the SNARE-family of proteins are known to be key regulators of the membrane-membrane fusion events required for intracellular membrane traffic. The ubiquitously expressed SNARE protein SNAP-23 regulates a wide variety of exocytosis events and is essential for mouse development. Germline deletion of SNAP-23 results in early embryonic lethality in mice, and for this reason we now describe mice and cell lines in which SNAP-23 can be conditionally-deleted using Cre-lox technology. Deletion of SNAP-23 in CD19-Cre expressing mice prevents B lymphocyte development and deletion of SNAP-23 using a variety of T lymphocyte-specific Cre mice prevents T lymphocyte development. Acute depletion of SNAP-23 in mouse fibroblasts leads to rapid apoptotic cell death. These data highlight the importance of SNAP-23 for cell survival and describe a mouse in which specific cell types can be eliminated by expression of tissue-specific Cre-recombinase. PMID:25706117

Membrane-bound Dickkopf-1 in Foxp3+ regulatory T cells suppresses T-cell-mediated autoimmune colitis.

PubMed

Chae, Wook-Jin; Park, Jong-Hyun; Henegariu, Octavian; Yilmaz, Saliha; Hao, Liming; Bothwell, Alfred L M

2017-10-01

Induction of tolerance is a key mechanism to maintain or to restore immunological homeostasis. Here we show that Foxp3 + regulatory T (Treg) cells use Dickkopf-1 (DKK-1) to regulate T-cell-mediated tolerance in the T-cell-mediated autoimmune colitis model. Treg cells from DKK-1 hypomorphic doubleridge mice failed to control CD4 + T-cell proliferation, resulting in CD4 T-cell-mediated autoimmune colitis. Thymus-derived Treg cells showed a robust expression of DKK-1 but not in naive or effector CD4 T cells. DKK-1 expression in Foxp3 + Treg cells was further increased upon T-cell receptor stimulation in vitro and in vivo. Interestingly, Foxp3 + Treg cells expressed DKK-1 in the cell membrane and the functional inhibition of DKK-1 using DKK-1 monoclonal antibody abrogated the suppressor function of Foxp3 + Treg cells. DKK-1 expression was dependent on de novo protein synthesis and regulated by the mitogen-activated protein kinase pathway but not by the canonical Wnt pathway. Taken together, our results highlight membrane-bound DKK-1 as a novel Treg-derived mediator to maintain immunological tolerance in T-cell-mediated autoimmune colitis. © 2017 The Authors. Immunology Published by John Wiley & Sons Ltd.

Antigen sensitivity of CD22-specific chimeric TCR is modulated by target epitope distance from the cell membrane.

PubMed

James, Scott E; Greenberg, Philip D; Jensen, Michael C; Lin, Yukang; Wang, Jinjuan; Till, Brian G; Raubitschek, Andrew A; Forman, Stephen J; Press, Oliver W

2008-05-15

We have targeted CD22 as a novel tumor-associated Ag for recognition by human CTL genetically modified to express chimeric TCR (cTCR) recognizing this surface molecule. CD22-specific cTCR targeting different epitopes of the CD22 molecule promoted efficient lysis of target cells expressing high levels of CD22 with a maximum lytic potential that appeared to decrease as the distance of the target epitope from the target cell membrane increased. Targeting membrane-distal CD22 epitopes with cTCR(+) CTL revealed defects in both degranulation and lytic granule targeting. CD22-specific cTCR(+) CTL exhibited lower levels of maximum lysis and lower Ag sensitivity than CTL targeting CD20, which has a shorter extracellular domain than CD22. This diminished sensitivity was not a result of reduced avidity of Ag engagement, but instead reflected weaker signaling per triggered cTCR molecule when targeting membrane-distal epitopes of CD22. Both of these parameters were restored by targeting a ligand expressing the same epitope, but constructed as a truncated CD22 molecule to approximate the length of a TCR:peptide-MHC complex. The reduced sensitivity of CD22-specific cTCR(+) CTL for Ag-induced triggering of effector functions has potential therapeutic applications, because such cells selectively lysed B cell lymphoma lines expressing high levels of CD22, but demonstrated minimal activity against autologous normal B cells, which express lower levels of CD22. Thus, our results demonstrate that cTCR signal strength, and consequently Ag sensitivity, can be modulated by differential choice of target epitopes with respect to distance from the cell membrane, allowing discrimination between targets with disparate Ag density.

Conformational antibody binding to a native, cell-free expressed GPCR in block copolymer membranes.

PubMed

de Hoog, Hans-Peter M; Lin JieRong, Esther M; Banerjee, Sourabh; Décaillot, Fabien M; Nallani, Madhavan

2014-01-01

G-protein coupled receptors (GPCRs) play a key role in physiological processes and are attractive drug targets. Their biophysical characterization is, however, highly challenging because of their innate instability outside a stabilizing membrane and the difficulty of finding a suitable expression system. We here show the cell-free expression of a GPCR, CXCR4, and its direct embedding in diblock copolymer membranes. The polymer-stabilized CXCR4 is readily immobilized onto biosensor chips for label-free binding analysis. Kinetic characterization using a conformationally sensitive antibody shows the receptor to exist in the correctly folded conformation, showing binding behaviour that is commensurate with heterologously expressed CXCR4.

Conformational Antibody Binding to a Native, Cell-Free Expressed GPCR in Block Copolymer Membranes

PubMed Central

de Hoog, Hans-Peter M.; Lin JieRong, Esther M.; Banerjee, Sourabh; Décaillot, Fabien M.; Nallani, Madhavan

2014-01-01

G-protein coupled receptors (GPCRs) play a key role in physiological processes and are attractive drug targets. Their biophysical characterization is, however, highly challenging because of their innate instability outside a stabilizing membrane and the difficulty of finding a suitable expression system. We here show the cell-free expression of a GPCR, CXCR4, and its direct embedding in diblock copolymer membranes. The polymer-stabilized CXCR4 is readily immobilized onto biosensor chips for label-free binding analysis. Kinetic characterization using a conformationally sensitive antibody shows the receptor to exist in the correctly folded conformation, showing binding behaviour that is commensurate with heterologously expressed CXCR4. PMID:25329156

Expression of membrane progesterone receptors (mPRs) in rat peripheral glial cell membranes and their potential role in the modulation of cell migration and protein expression.

PubMed

Castelnovo, Luca F; Magnaghi, Valerio; Thomas, Peter

2017-09-28

The role played by progestogens in modulating Schwann cell pathophysiology is well established. Progestogens exert their effects in these cells through both classical genomic and non-genomic mechanisms, the latter mediated by the GABA-A receptor. However, there is evidence that other receptors may be involved. Membrane progesterone receptors (mPRs) are novel 7-transmembrane receptors coupled to G proteins that have been characterized in different tissues and cells, including the central nervous system (CNS). The mPRs were shown to mediate some of progestogens' neuroprotective effects in the CNS, and to be upregulated in glial cells after traumatic brain injury. Based on this evidence, this paper investigated the possible involvement of mPRs in mediating progestogen actions in S42 Schwann cells. All five mPR isoforms and progesterone receptor membrane component 1 (PGRMC1) were detected in Schwann cells, and were present on the cell membrane. Progesterone and the mPR-specific agonist, Org-OD-02-0 (02) bound to these membranes, indicating the presence of functional mPRs. The mPR agonist 02 rapidly increased cell migration in an in vitro assay, suggesting a putative role of mPRs in the nerve regeneration process. Treatment with pertussis toxin and 8-Br-cAMP blocked 02-induced cell migration, suggesting this progestogen action is mediated by activation of an inhibitory G protein, leading to a decrease in intracellular cAMP levels. In contrast, long-term mPR activation led to increased expression levels of myelin associated glycoprotein (MAG). Taken together, these findings show that mPRs are present and active in Schwann cells and have a role in modulating their physiological processes. Copyright © 2017 Elsevier Inc. All rights reserved.

Expression Profile of Drug and Nutrient Absorption Related Genes in Madin-Darby Canine Kidney (MDCK) Cells Grown under Differentiation Conditions.

PubMed

Quan, Yong; Jin, Yisheng; Faria, Teresa N; Tilford, Charles A; He, Aiqing; Wall, Doris A; Smith, Ronald L; Vig, Balvinder S

2012-06-18

The expression levels of genes involved in drug and nutrient absorption were evaluated in the Madin-Darby Canine Kidney (MDCK) in vitro drug absorption model. MDCK cells were grown on plastic surfaces (for 3 days) or on Transwell® membranes (for 3, 5, 7, and 9 days). The expression profile of genes including ABC transporters, SLC transporters, and cytochrome P450 (CYP) enzymes was determined using the Affymetrix® Canine GeneChip®. Expression of genes whose probe sets passed a stringent confirmation process was examined. Expression of a few transporter (MDR1, PEPT1 and PEPT2) genes in MDCK cells was confirmed by RT-PCR. The overall gene expression profile was strongly influenced by the type of support the cells were grown on. After 3 days of growth, expression of 28% of the genes was statistically different (1.5-fold cutoff, p < 0.05) between the cells grown on plastic and Transwell® membranes. When cells were differentiated on Transwell® membranes, large changes in gene expression profile were observed during the early stages, which then stabilized after 5-7 days. Only a small number of genes encoding drug absorption related SLC, ABC, and CYP were detected in MDCK cells, and most of them exhibited low hybridization signals. Results from this study provide valuable reference information on endogenous gene expression in MDCK cells that could assist in design of drug-transporter and/or drug-enzyme interaction studies, and help interpret the contributions of various transporters and metabolic enzymes in studies with MDCK cells.

Expression Profile of Drug and Nutrient Absorption Related Genes in Madin-Darby Canine Kidney (MDCK) Cells Grown under Differentiation Conditions

PubMed Central

Quan, Yong; Jin, Yisheng; Faria, Teresa N.; Tilford, Charles A.; He, Aiqing; Wall, Doris A.; Smith, Ronald L.; Vig, Balvinder S.

2012-01-01

The expression levels of genes involved in drug and nutrient absorption were evaluated in the Madin-Darby Canine Kidney (MDCK) in vitro drug absorption model. MDCK cells were grown on plastic surfaces (for 3 days) or on Transwell® membranes (for 3, 5, 7, and 9 days). The expression profile of genes including ABC transporters, SLC transporters, and cytochrome P450 (CYP) enzymes was determined using the Affymetrix® Canine GeneChip®. Expression of genes whose probe sets passed a stringent confirmation process was examined. Expression of a few transporter (MDR1, PEPT1 and PEPT2) genes in MDCK cells was confirmed by RT-PCR. The overall gene expression profile was strongly influenced by the type of support the cells were grown on. After 3 days of growth, expression of 28% of the genes was statistically different (1.5-fold cutoff, p < 0.05) between the cells grown on plastic and Transwell® membranes. When cells were differentiated on Transwell® membranes, large changes in gene expression profile were observed during the early stages, which then stabilized after 5–7 days. Only a small number of genes encoding drug absorption related SLC, ABC, and CYP were detected in MDCK cells, and most of them exhibited low hybridization signals. Results from this study provide valuable reference information on endogenous gene expression in MDCK cells that could assist in design of drug-transporter and/or drug-enzyme interaction studies, and help interpret the contributions of various transporters and metabolic enzymes in studies with MDCK cells. PMID:24300234

Phosphatidylserine metabolism modification precedes manganese-induced apoptosis and phosphatidylserine exposure in PC12 cells.

PubMed

Ferrara, G; Gambelunghe, A; Mozzi, R; Marchetti, M C; Migliorati, G; Muzi, G; Buratta, S

2013-12-01

Long-term exposure to high manganese (Mn) levels can lead to Parkinson-like neurological disorders. Molecular mechanisms underlying Mn cytotoxicity have been not defined. It is known that Mn induces apoptosis in PC12 cells and that this involves the activation of some signal transduction pathways. Although the role of phospholipids in apoptosis and signal transduction is well-known, the membrane phospholipid component in Mn-related damage has not yet been investigated. Phosphatidylserine (PS) facilitates protein translocation from cytosol to plasma membrane and PS exposure on the cell surface allows macrophage recognition of apoptotic cells. This study investigates the effects of MnCl2 on PS metabolism in PC12 cells, relating them to those on cell apoptosis. Apoptosis induction decreased PS radioactivity of PC12 cells incubated with radioactive serine. MnCl2 reduced PS radioactivity even under conditions that did not affect cell viability or PS exposure, suggesting that the effects on PS metabolism may represent an early event in cell apoptosis. Thus the latter conditions that also induced a greater PS decarboxylation were utilized for further investigating on the effects on PS synthesis, by measuring the activity and expression of PS-synthesizing enzymes, in cell lysates and in total cellular membranes (TM). Compared with corresponding controls, enzyme activity of MnCl2-treated cells was lower in cell lysates and greater in TM. Evaluating the expression of two isoforms of PS-synthesizing enzyme (PSS), PSSII was increased both in cell lysate and TM, while PSSI was unchanged. MnCl2 addition to control cell lysate reduced enzyme activity. These results suggest Mn plays a dual role on PS synthesis. Once inside the cell, Mn inhibits the enzyme/s, thus accounting for reduced PS synthesis in lysates and intact cells. On the other hand, it increases PSSII expression in cell membranes. The possibility that this occurs to counteract the direct effects of Mn ions on enzyme activity cannot be excluded. The effects on membrane enzyme activity and expression may also participate to PS exposure, observed at longer periods of treatment, by increasing membrane PS content. Copyright © 2013 Elsevier Inc. All rights reserved.

LC-MS/MS Based Quantitation of ABC and SLC Transporter Proteins in Plasma Membranes of Cultured Primary Human Retinal Pigment Epithelium Cells and Immortalized ARPE19 Cell Line.

PubMed

Pelkonen, Laura; Sato, Kazuki; Reinisalo, Mika; Kidron, Heidi; Tachikawa, Masanori; Watanabe, Michitoshi; Uchida, Yasuo; Urtti, Arto; Terasaki, Tetsuya

2017-03-06

The retinal pigment epithelium (RPE) forms the outer blood-retinal barrier between neural retina and choroid. The RPE has several important vision supporting functions, such as transport mechanisms that may also modify pharmacokinetics in the posterior eye segment. Expression of plasma membrane transporters in the RPE cells has not been quantitated. The aim of this study was to characterize and compare transporter protein expression in the ARPE19 cell line and hfRPE (human fetal RPE) cells by using quantitative targeted absolute proteomics (QTAP). Among 41 studied transporters, 16 proteins were expressed in hfRPE and 13 in ARPE19 cells. MRP1, MRP5, GLUT1, 4F2hc, TAUT, CAT1, LAT1, and MATE1 proteins were detected in both cell lines within 4-fold differences. MPR7, OAT2 and RFC1 were detected in the hfRPE cells, but their expression levels were below the limit of quantification in ARPE19 cells. PCFT was detected in both studied cell lines, but the expression was over 4-fold higher in hfRPE cells. MCT1, MCT4, MRP4, and Na + /K + ATPase were upregulated in the ARPE19 cell line showing over 4-fold differences in the quantitative expression values. Expression levels of 25 transporters were below the limit of quantification in both cell models. In conclusion, we present the first systematic and quantitative study on transporter protein expression in the plasma membranes of ARPE19 and hfRPE cells. Overall, transporter expression in the ARPE19 and hfRPE cells correlated well and the absolute expression levels were similar, but not identical. The presented quantitative expression levels could be a useful basis for further studies on drug permeation in the outer blood-retinal barrier.

Ubiquitination by the Membrane-associated RING-CH-8 (MARCH-8) Ligase Controls Steady-state Cell Surface Expression of Tumor Necrosis Factor-related Apoptosis Inducing Ligand (TRAIL) Receptor 1*

PubMed Central

van de Kooij, Bert; Verbrugge, Inge; de Vries, Evert; Gijsen, Merel; Montserrat, Veronica; Maas, Chiel; Neefjes, Jacques; Borst, Jannie

2013-01-01

The eleven members of the membrane-associated RING-CH (MARCH) ubiquitin ligase family are relatively unexplored. Upon exogenous (over)expression, a number of these ligases can affect the trafficking of membrane molecules. However, only for MARCH-1 endogenous functions have been demonstrated. For the other endogenous MARCH proteins, no functions or substrates are known. We report here that TRAIL-R1 is a physiological substrate of the endogenous MARCH-8 ligase. Human TRAIL-R1 and R2 play a role in immunosurveillance and are targets for cancer therapy, because they selectively induce apoptosis in tumor cells. We demonstrate that TRAIL-R1 is down-regulated from the cell surface, with great preference over TRAIL-R2, by exogenous expression of MARCH ligases that are implicated in endosomal trafficking, such as MARCH-1 and -8. MARCH-8 attenuated TRAIL-R1 cell surface expression and apoptosis signaling by virtue of its ligase activity. This suggested that ubiquitination of TRAIL-R1 was instrumental in its down-regulation by MARCH-8. Indeed, in cells with endogenous MARCH expression, TRAIL-R1 was ubiquitinated at steady-state, with the conserved membrane-proximal lysine 273 as one of the potential acceptor sites. This residue was also essential for the interaction of TRAIL-R1 with MARCH-1 and MARCH-8 and its down-regulation by these ligases. Gene silencing identified MARCH-8 as the endogenous ligase that ubiquitinates TRAIL-R1 and attenuates its cell surface expression. These findings reveal that endogenous MARCH-8 regulates the steady-state cell surface expression of TRAIL-R1. PMID:23300075

siRNA-based Analysis of the Abrogation of the Protective Function of Membrane-associated Catalase of Tumor Cells.

PubMed

Bauer, Georg

2017-02-01

Tumor cells, in contrast to non-malignant cells, show sustained expression of membrane-associated NADPH oxidase-1 and therefore generate extracellular superoxide anions and their dismutation product H 2 O 2 In order to prevent intercellular reactive oxygen species/reactive nitrogen species (ROS/RNS)-dependent apoptosis-inducing signaling, tumor cells need to express membrane-associated catalase that interferes with HOCl and nitric oxide/peroxynitrite signaling. Catalase is attached to tumor cells through the activity of transglutaminase-2 and is prevented from superoxide anion-dependent inhibition through coexpression of membrane-associated superoxide dismutase. Therefore, specific inhibition of membrane-associated catalase should reactivate intercellular ROS/RNS-dependent apoptosis-inducing signaling. These processes are analyzed here through small interfering RNA-mediated knockdown of essential signaling compounds. This allows to establish a rather comprehensive picture of intercellular ROS/RNS signaling that may be instrumental for future therapeutic approaches. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Antitumor effects of a tumor cell vaccine expressing a membrane-bound form of the IL-12 p35 subunit.

PubMed

Lim, Ho Yong; Ju, Hee Young; Chung, Hee-Yong; Kim, Young Sang

2010-08-15

We investigated whether expression of the IL-12 p35 subunit in membrane-bound form in tumor cells enhanced their immunogenicity. Since p35 is only secreted when associated with the IL-12 p40 subunit, we generated tumor cells expressing membrane-bound forms of p35 and p40 as chimeras with the transmembrane/cytoplasmic region of TNFα (mbIL-12p35 and mbIL-12p40). The relevant vectors were transfected into MethA fibrosarcoma cells, and mbIL-12p35 or mbIL-12p40-expressing tumor clones were isolated and their ability to induce antitumor immunity studied. Cells of the mbIL-12p35 tumor clone induced CD69 expression and IFNγ production in purified CD8(+) T cells in vitro, and their in vivo tumorigenicity was reduced. Cells of the mbIL-12p40 tumor clone failed to show either of these activities. Mice that had rejected cells of the mbIL-12p35 tumor clone possessed systemic antitumor immunity to wild type tumor cells. The growth rate of mbIL-12p35 tumor cells was greater in CD8(+) T cell-depleted mice than in CD4(+) T-cell- and NK cell-depleted mice or normal mice, suggesting that CD8(+) T cells were mainly responsible for the antitumor immunity. These results indicate that expression of mbIL-12p35 on tumor cells enhances their immunogenicity by increasing their ability to activate CD8(+) T cells, possibly by direct priming.

Apical Plasma Membrane Mispolarization of NaK-ATPase in Polycystic Kidney Disease Epithelia Is Associated with Aberrant Expression of the β2 Isoform

PubMed Central

Wilson, Patricia D.; Devuyst, Olivier; Li, Xiaohong; Gatti, Laura; Falkenstein, Doris; Robinson, Shawn; Fambrough, Douglas; Burrow, Christopher R.

2000-01-01

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease of the kidney, characterized by cystic enlargement of renal tubules, aberrant epithelial proliferation, and ion and fluid secretion into the lumen. Previous studies have shown abnormalities in polarization of membrane proteins, including mislocalization of the NaK-ATPase to the apical plasma membranes of cystic epithelia. Apically located NaK-ATPase has previously been shown to be fully functional in vivo and in membrane-grown ADPKD epithelial cells in vitro, where basal-to-apical 22Na transport was inhibited by application of ouabain to the apical membrane compartment. Studies were conducted with polymerase chain reaction-generated specific riboprobes and polyclonal peptide antibodies against human sequences of α1, α3, β1, and β2 subunits of NaK-ATPase. High levels of expression of α1 and β1 messenger RNA were detected in ADPKD and age-matched normal adult kidneys in vivo, whereas β2 messenger RNA was detected only in ADPKD kidneys. Western blot analysis and immunocytochemical studies showed that, in normal adult kidneys, peptide subunit-specific antibodies against α1 and β1 localized to the basolateral membranes of normal renal tubules, predominantly thick ascending limbs of Henle’s loop. In ADPKD kidneys, α1 and β2 subunits were localized to the apical epithelial cell membranes, whereas β1 was distributed throughout the cytoplasm and predominantly in the endoplasmic reticulum, but was not seen associated with cystic epithelial cell membranes or in cell membrane fractions. Polarizing, renal-derived epithelial Madin Darby canine kidney cells, stably expressing normal or N-terminally truncated chicken β1 subunits, showed selective accumulation in the basolateral Madin Darby canine kidney cell surface, whereas c-myc epitope-tagged chicken β2 or human β2 subunits accumulated selectively in the apical cell surface. Similarly, human ADPKD epithelial cell lines, which endogenously expressed α1 and β2 NaK-ATPase subunits, showed colocalization at the apical cell surface and coassociation by immunoprecipitation analysis. These results are consistent with a model in which the additional transcription and translation of the β2 subunit of NaK-ATPase may result in the apical mislocalization of NaK-ATPase in ADPKD cystic epithelia. PMID:10623674

Placental membrane aging and HMGB1 signaling associated with human parturition.

PubMed

Menon, Ramkumar; Behnia, Faranak; Polettini, Jossimara; Saade, George R; Campisi, Judith; Velarde, Michael

2016-02-01

Aging is associated with the onset of several diseases in various organ systems; however, different tissues may age differently, rendering some of them dysfunctional sooner than others. Placental membranes (fetal amniochorionic membranes) protect the fetus throughout pregnancy, but their longevity is limited to the duration of pregnancy. The age-associated dysfunction of these membranes is postulated to trigger parturition. Here, we investigated whether cellular senescence-the loss of cell division potential as a consequence of stress-is involved in placental membrane function at term. We show telomere reduction, p38 MAPK activation, increase in p21 expression, loss of lamin B1 loss, increase in SA-β-galactosidase , and senescence-associated secretory phenotype (SASP) gene expression in placental membranes after labor and delivery (term labor [TL]) compared to membranes prior to labor at term (term, not-in-labor [TNIL]). Exposing TNIL placental membranes to cigarette smoke extract, an oxidative stress inducer, also induced markers of cellular senescence similar to those in TL placental membranes. Bioinformatics analysis of differentially expressed SASP genes revealed HMGB1 signaling among the top pathways involved in labor. Further, we show that recombinant HMGB1 upregulates the expression of genes associated with parturition in myometrial cells. These data suggest that the natural physiologic aging of placental tissues is associated with cellular senescence and human parturition.

Proteomic analysis of corneal endothelial cell-descemet membrane tissues reveals influence of insulin dependence and disease severity in type 2 diabetes mellitus.

PubMed

Skeie, Jessica M; Aldrich, Benjamin T; Goldstein, Andrew S; Schmidt, Gregory A; Reed, Cynthia R; Greiner, Mark A

2018-01-01

The objective of this study was to characterize the proteome of the corneal endothelial cell layer and its basement membrane (Descemet membrane) in humans with various severities of type II diabetes mellitus compared to controls, and identify differentially expressed proteins across a range of diabetic disease severities that may influence corneal endothelial cell health. Endothelium-Descemet membrane complex tissues were peeled from transplant suitable donor corneas. Protein fractions were isolated from each sample and subjected to multidimensional liquid chromatography and tandem mass spectrometry. Peptide spectra were matched to the human proteome, assigned gene ontology, and grouped into protein signaling pathways unique to each of the disease states. We identified an average of 12,472 unique proteins in each of the endothelium-Descemet membrane complex tissue samples. There were 2,409 differentially expressed protein isoforms that included previously known risk factors for type II diabetes mellitus related to metabolic processes, oxidative stress, and inflammation. Gene ontology analysis demonstrated that diabetes progression has many protein footprints related to metabolic processes, binding, and catalysis. The most represented pathways involved in diabetes progression included mitochondrial dysfunction, cell-cell junction structure, and protein synthesis regulation. This proteomic dataset identifies novel corneal endothelial cell and Descemet membrane protein expression in various stages of diabetic disease. These findings give insight into the mechanisms involved in diabetes progression relevant to the corneal endothelium and its basement membrane, prioritize new pathways for therapeutic targeting, and provide insight into potential biomarkers for determining the health of this tissue.

Voltage-Gated Potassium Channels Kv1.3--Potentially New Molecular Target in Cancer Diagnostics and Therapy.

PubMed

Teisseyre, Andrzej; Gąsiorowska, Justyna; Michalak, Krystyna

2015-01-01

Voltage-gated potassium channels, Kv1.3, which were discovered in 1984, are integral membrane proteins which are activated ("open") upon change of the cell membrane potential, enabling a passive flux of potassium ions across the cell membrane. The channels are expressed in many different tissues, both normal and cancer. Since 2005 it has been known that the channels are expressed not only in the plasma membrane, but also in the inner mitochondrial membrane. The activity of Kv1.3 channels plays an important role, among others, in setting the cell resting membrane potential, cell proliferation, apoptosis and volume regulation. For some years, these channels have been considered a potentially new molecular target in both the diagnostics and therapy of some cancer diseases. This review article focuses on: 1) changes of expression of the channels in cancer disorders with special regard to correlations between the channels' expression and stage of the disease, 2) influence of inhibitors of Kv1.3 channels on proliferation and apoptosis of cancer cells, 3) possible future applications of Kv1.3 channels' inhibitors in therapy of some cancer diseases. In the last section, the results of studies performed in our Laboratory of Bioelectricity on the influence of selected biologically active plant-derived compounds from the groups of flavonoids and stilbenes and their natural and synthetic derivatives on the activity of Kv1.3 channels in normal and cancer cells are reviewed. A possible application of some compounds from these groups to support therapy of cancer diseases, such as breast, colon and lymph node cancer, and melanoma or chronic lymphocytic leukemia (B-CLL), is announced.

A Cell-Cell Fusion Assay to Assess Arenavirus Envelope Glycoprotein Membrane-Fusion Activity.

PubMed

York, Joanne; Nunberg, Jack H

2018-01-01

For many viruses that enter their target cells through pH-dependent fusion of the viral and endosomal membranes, cell-cell fusion assays can provide an experimental platform for investigating the structure-function relationships that promote envelope glycoprotein membrane-fusion activity. Typically, these assays employ effector cells expressing the recombinant envelope glycoprotein on the cell surface and target cells engineered to quantitatively report fusion with the effector cell. In the protocol described here, Vero cells are transfected with a plasmid encoding the arenavirus envelope glycoprotein complex GPC and infected with the vTF7-3 vaccinia virus expressing the bacteriophage T7 RNA polymerase. These effector cells are mixed with target cells infected with the vCB21R-lacZ vaccinia virus encoding a β-galactosidase reporter under the control of the T7 promoter. Cell-cell fusion is induced upon exposure to low-pH medium (pH 5.0), and the resultant expression of the β-galactosidase reporter is quantitated using a chemiluminescent substrate. We have utilized this robust microplate cell-cell fusion assay extensively to study arenavirus entry and its inhibition by small-molecule fusion inhibitors.

The Role of Cargo Proteins in GGA Recruitment

PubMed Central

Hirst, Jennifer; Seaman, Matthew N J; Buschow, Sonja I; Robinson, Margaret S

2007-01-01

Coat proteins are recruited onto membranes to form vesicles that transport cargo from one compartment to another, but the extent to which the cargo helps to recruit the coat proteins is still unclear. Here we have examined the role of cargo in the recruitment of Golgi-localized, γ-ear-containing, ADP ribosylation factor (ARF)-binding proteins (GGAs) onto membranes in HeLa cells. Moderate overexpression of CD8 chimeras with cytoplasmic tails containing DXXLL-sorting signals, which bind to GGAs, increased the localization of all three GGAs to perinuclear membranes, as observed by immunofluorescence. GGA2 was also expressed at approximately twofold higher levels in these cells because it was degraded more slowly. However, this difference only partially accounted for the increase in membrane localization because there was a approximately fivefold increase in GGA2 associated with crude membranes and a ∼12-fold increase in GGA2 associated with clathrin-coated vesicles (CCVs) in cells expressing CD8-DXXLL chimeras. The effect of cargo proteins on GGA recruitment was reconstituted in vitro using permeabilized control and CD8-DXXLL-expressing cells incubated with cytosol containing recombinant GGA2 constructs. Together, these results demonstrate that cargo proteins contribute to the recruitment of GGAs onto membranes and to the formation of GGA-positive CCVs. PMID:17451558

Sorting of Marburg Virus Surface Protein and Virus Release Take Place at Opposite Surfaces of Infected Polarized Epithelial Cells

PubMed Central

Sänger, Christian; Mühlberger, Elke; Ryabchikova, Elena; Kolesnikova, Larissa; Klenk, Hans-Dieter; Becker, Stephan

2001-01-01

Marburg virus, a filovirus, causes severe hemorrhagic fever with hitherto poorly understood molecular pathogenesis. We have investigated here the vectorial transport of the surface protein GP of Marburg virus in polarized epithelial cells. To this end, we established an MDCKII cell line that was able to express GP permanently (MDCK-GP). The functional integrity of GP expressed in these cells was analyzed using vesicular stomatitis virus pseudotypes. Further experiments revealed that GP is transported in MDCK-GP cells mainly to the apical membrane and is released exclusively into the culture medium facing the apical membrane. When MDCKII cells were infected with Marburg virus, the majority of GP was also transported to the apical membrane, suggesting that the protein contains an autonomous apical transport signal. Release of infectious progeny virions, however, took place exclusively at the basolateral membrane of the cells. Thus, vectorial budding of Marburg virus is presumably determined by factors other than the surface protein. PMID:11152500

Isolated Anxa5{sup +}/Sca-1{sup +} perivascular cells from mouse meningeal vasculature retain their perivascular phenotype in vitro and in vivo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brachvogel, Bent; Pausch, Friederike; Farlie, Peter

2007-07-15

Pericytes are closely associated with endothelial cells, contribute to vascular stability and represent a potential source of mesenchymal progenitor cells. Using the specifically expressed annexin A5-LacZ fusion gene (Anxa5-LacZ), it became possible to isolate perivascular cells (PVC) from mouse tissues. These cells proliferate and can be cultured without undergoing senescence for multiple passages. PVC display phenotypic characteristics of pericytes, as they express pericyte-specific markers (NG2-proteoglycan, desmin, {alpha}SMA, PDGFR-{beta}). They also express stem cell marker Sca-1, whereas endothelial (PECAM), hematopoietic (CD45) or myeloid (F4/80, CD11b) lineage markers are not detectable. These characteristics are in common with the pericyte-like cell line 10T1/2.more » PVC also display a phagocytoic activity higher than 10T1/2 cells. During coculture with endothelial cells both cell types stimulate angiogenic processes indicated by an increased expression of PECAM in endothelial cells and specific deposition of basement membrane proteins. PVC show a significantly increased induction of endothelial specific PECAM expression compared to 10T1/2 cells. Accordingly, in vivo grafts of PVC aggregates onto chorioallantoic membranes of quail embryos recruit endothelial cells, get highly vascularized and deposit basement membrane components. These data demonstrate that isolated Anxa5-LacZ{sup +} PVC from mouse meninges retain their capacity for differentiation to pericyte-like cells and contribute to angiogenic processes.« less

Disturbed vesicular trafficking of membrane proteins in prion disease.

PubMed

Uchiyama, Keiji; Miyata, Hironori; Sakaguchi, Suehiro

2013-01-01

The pathogenic mechanism of prion diseases remains unknown. We recently reported that prion infection disturbs post-Golgi trafficking of certain types of membrane proteins to the cell surface, resulting in reduced surface expression of membrane proteins and abrogating the signal from the proteins. The surface expression of the membrane proteins was reduced in the brains of mice inoculated with prions, well before abnormal symptoms became evident. Prions or pathogenic prion proteins were mainly detected in endosomal compartments, being particularly abundant in recycling endosomes. Some newly synthesized membrane proteins are delivered to the surface from the Golgi apparatus through recycling endosomes, and some endocytosed membrane proteins are delivered back to the surface through recycling endosomes. These results suggest that prions might cause neuronal dysfunctions and cell loss by disturbing post-Golgi trafficking of membrane proteins via accumulation in recycling endosomes. Interestingly, it was recently shown that delivery of a calcium channel protein to the cell surface was impaired and its function was abrogated in a mouse model of hereditary prion disease. Taken together, these results suggest that impaired delivery of membrane proteins to the cell surface is a common pathogenic event in acquired and hereditary prion diseases.

Cell-based capacitance sensor for analysis of EGFR expression on cell membrane

NASA Astrophysics Data System (ADS)

Shin, Dong-Myeong; Shin, Yong-Cheol; Ha, Ji Hye; Lee, Jong-Ho; Han, Dong-Wook; Kim, Jong-Man; Kim, Hyung Kook; Hwang, Yoon-Hwae

2013-02-01

Cancer cells have many kinds of cancer biomarkers. Among them, the epidermal growth factor (EGF) receptors can show a possibility for a cancer marker because the over-expression of EGF receptor is related with fibrous, colorectal, cervical and gastric tumorigenesis. We fabricated the capacitance sensor with a gap area of 50 μm × 200 μm by using photolithography and lift-off method. Using the capacitance sensor, we investigated the time dependent capacitance changes of different kinds of fibrous cells, such as HT1080 fibrosarcoma, L-929 fibroblast cell line and nHDF dermal fibroblast primary cell. We found that when we put the EGF, the capacitance decreased due to the immobilization of EGF to EGF receptor on the cell membrane. The quantitative determination of EGF receptor level for various fibrous cells was carried out and the results showed good correlation with conventional method. Based on our results, we suggest that the capacitance sensor can measure the expression level of the EGF receptor on cell membrane and be a good candidate as a cancer diagnosis.

Effect of aniracetam on phosphatidylinositol transfer protein alpha in cytosolic and plasma membrane fractions of astrocytes subjected to simulated ischemia in vitro.

PubMed

Gabryel, Bozena; Chalimoniuk, Małgorzata; Małecki, Andrzej; Strosznajder, Joanna B

2005-01-01

Brain ischemia affects phosphoinositide metabolism and the level of lipid-derived second messengers. Phosphatidylinositol transfer proteins (PI-PTs) are responsible for the transport of phosphatidylinositol (PI) and other phospholipids through membranes. Isoform of PI-TPs (PI-TPalpha) is an essential component in ensuring substrate supply for phospholipase C (PLC). The current study was conducted to examine potential effect of aniracetam on PI-TPalpha expression and to characterize the PI-TPalpha isoform distribution between membrane and cytosol fractions of astrocytes exposed to simulated ischemia in vitro. After 8 h period of ischemia, the level of PI-TPalpha was significantly higher in cytosol (by about 28%) as well as in membrane fraction (by about 80%) in comparison with control. We have found that aniracetam treatment of astrocytes in normoxia significantly increased the level of PI-TPalpha in membrane fraction with a maximal effect at 0.1 microM concentration of aniracetam (by about 195% of control). In membrane fractions of ischemic cells, aniracetam increased PI-TPalpha expression in a concentration-dependent manner. In ischemic cells, aniracetam (10 microM) has elevated PI-TPalpha expression up to 155% and 428% in cytosolic and membrane fractions in comparison with ischemic untreated cells, respectively. The study has shown that aniracetam significantly activates PI-TPalpha in cell membrane fraction and this effect might be connected with previously described activation of MAP kinase cascade.

Mechanism of biological denitrification inhibition: procyanidins induce an allosteric transition of the membrane-bound nitrate reductase through membrane alteration.

PubMed

Bardon, Clément; Poly, Franck; Piola, Florence; Pancton, Muriel; Comte, Gilles; Meiffren, Guillaume; Haichar, Feth el Zahar

2016-05-01

Recently, it has been shown that procyanidins from Fallopia spp. inhibit bacterial denitrification, a phenomenon called biological denitrification inhibition (BDI). However, the mechanisms involved in such a process remain unknown. Here, we investigate the mechanisms of BDI involving procyanidins, using the model strain Pseudomonas brassicacearum NFM 421. The aerobic and anaerobic (denitrification) respiration, cell permeability and cell viability of P. brassicacearum were determined as a function of procyanidin concentration. The effect of procyanidins on the bacterial membrane was observed using transmission electronic microscopy. Bacterial growth, denitrification, NO3- and NO2-reductase activity, and the expression of subunits of NO3- (encoded by the gene narG) and NO2-reductase (encoded by the gene nirS) under NO3 or NO2 were measured with and without procyanidins. Procyanidins inhibited the denitrification process without affecting aerobic respiration at low concentrations. Procyanidins also disturbed cell membranes without affecting cell viability. They specifically inhibited NO3- but not NO2-reductase.Pseudomonas brassicacearum responded to procyanidins by over-expression of the membrane-bound NO3-reductase subunit (encoded by the gene narG). Our results suggest that procyanidins can specifically inhibit membrane-bound NO3-reductase inducing enzymatic conformational changes through membrane disturbance and that P. brassicacearum responds by over-expressing membrane-bound NO3-reductase. Our results lead the way to a better understanding of BDI. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Plasma Membrane Proteomics of Human Breast Cancer Cell Lines Identifies Potential Targets for Breast Cancer Diagnosis and Treatment

PubMed Central

Ziegler, Yvonne S.; Moresco, James J.; Tu, Patricia G.; Yates, John R.; Nardulli, Ann M.

2014-01-01

The use of broad spectrum chemotherapeutic agents to treat breast cancer results in substantial and debilitating side effects, necessitating the development of targeted therapies to limit tumor proliferation and prevent metastasis. In recent years, the list of approved targeted therapies has expanded, and it includes both monoclonal antibodies and small molecule inhibitors that interfere with key proteins involved in the uncontrolled growth and migration of cancer cells. The targeting of plasma membrane proteins has been most successful to date, and this is reflected in the large representation of these proteins as targets of newer therapies. In view of these facts, experiments were designed to investigate the plasma membrane proteome of a variety of human breast cancer cell lines representing hormone-responsive, ErbB2 over-expressing and triple negative cell types, as well as a benign control. Plasma membranes were isolated by using an aqueous two-phase system, and the resulting proteins were subjected to mass spectrometry analysis. Overall, each of the cell lines expressed some unique proteins, and a number of proteins were expressed in multiple cell lines, but in patterns that did not always follow traditional clinical definitions of breast cancer type. From our data, it can be deduced that most cancer cells possess multiple strategies to promote uncontrolled growth, reflected in aberrant expression of tyrosine kinases, cellular adhesion molecules, and structural proteins. Our data set provides a very rich and complex picture of plasma membrane proteins present on breast cancer cells, and the sorting and categorizing of this data provides interesting insights into the biology, classification, and potential treatment of this prevalent and debilitating disease. PMID:25029196

A cDNA Immunization Strategy to Generate Nanobodies against Membrane Proteins in Native Conformation

PubMed Central

Eden, Thomas; Menzel, Stephan; Wesolowski, Janusz; Bergmann, Philine; Nissen, Marion; Dubberke, Gudrun; Seyfried, Fabienne; Albrecht, Birte; Haag, Friedrich; Koch-Nolte, Friedrich

2018-01-01

Nanobodies (Nbs) are soluble, versatile, single-domain binding modules derived from the VHH variable domain of heavy-chain antibodies naturally occurring in camelids. Nbs hold huge promise as novel therapeutic biologics. Membrane proteins are among the most interesting targets for therapeutic Nbs because they are accessible to systemically injected biologics. In order to be effective, therapeutic Nbs must recognize their target membrane protein in native conformation. However, raising Nbs against membrane proteins in native conformation can pose a formidable challenge since membrane proteins typically contain one or more hydrophobic transmembrane regions and, therefore, are difficult to purify in native conformation. Here, we describe a highly efficient genetic immunization strategy that circumvents these difficulties by driving expression of the target membrane protein in native conformation by cells of the immunized camelid. The strategy encompasses ballistic transfection of skin cells with cDNA expression plasmids encoding one or more orthologs of the membrane protein of interest and, optionally, other costimulatory proteins. The plasmid is coated onto 1 µm gold particles that are then injected into the shaved and depilated skin of the camelid. A gene gun delivers a helium pulse that accelerates the DNA-coated particles to a velocity sufficient to penetrate through multiple layers of cells in the skin. This results in the exposure of the extracellular domains of the membrane protein on the cell surface of transfected cells. Repeated immunization drives somatic hypermutation and affinity maturation of target-specific heavy-chain antibodies. The VHH/Nb coding region is PCR-amplified from B cells obtained from peripheral blood or a lymph node biopsy. Specific Nbs are selected by phage display or by screening of Nb-based heavy-chain antibodies expressed as secretory proteins in transfected HEK cells. Using this strategy, we have successfully generated agonistic and antagonistic Nbs against several cell surface ecto-enzymes and ligand-gated ion channels. PMID:29410663

Membrane receptor-independent inhibitory effect of melatonin on androgen production in porcine theca cells.

PubMed

Wang, Heng; Pu, Yong; Luo, Lei; Li, Yunsheng; Zhang, Yunhai; Cao, Zubing

2018-06-01

Excessive secretion of androgens including androstenedione and testosterone in theca cells frequently causes female infertility in mammals. Melatonin is a potent inhibitor of androgen production in gonadal cells of several species in a membrane receptor-dependent manner. However, the function of melatonin in steroidogenesis of porcine theca cells remains unclear. Here we report that melatonin inhibits androgen biosynthesis independently of its membrane receptors in pigs. Using flow cytometry, immunofluorescence and RT-PCR we showed that the vast majority of cells isolated from the theca layer of antral follicles are indeed theca cells. Furthermore, we demonstrated that of the two of melatonin membrane receptors encoded in the porcine genome, theca cells exclusively express melatonin receptor 1B. Cell counting analysis indicated that different concentrations of melatonin did not alter the normal viability and proliferation of theca cells. Additionally, hormone radioimmunoassay and qPCR respectively showed that a high concentration of melatonin significantly repressed both androgen production and expression of steroidogenic genes involving StAR, CYP11A1, HSD3β and SET (P < 0.05), but did not impair progesterone production. Interestingly, these effects were not reversed by N-acetyl-2-benzyltryptamin, a melatonin membrane receptor antagonist. Overall, these results demonstrate that melatonin inhibits androgen production in porcine theca cells independently of its membrane receptor. Copyright © 2018 Elsevier Inc. All rights reserved.

Membrane Protein Production in E. coli Lysates in Presence of Preassembled Nanodiscs.

PubMed

Rues, Ralf-Bernhardt; Gräwe, Alexander; Henrich, Erik; Bernhard, Frank

2017-01-01

Cell-free expression allows to synthesize membrane proteins in completely new formats that can relatively easily be customized for particular applications. Amphiphilic superstructures such as micelles, lipomicelles, or nanodiscs can be provided as nano-devices for the solubilization of membrane proteins. Defined empty bilayers in the form of nanodiscs offer native like environments for membrane proteins, supporting functional folding, proper oligomeric assembly as well as stability. Even very difficult and detergent-sensitive membrane proteins can be addressed by the combination of nanodisc technology with efficient cell-free expression systems as the direct co-translational insertion of nascent membrane proteins into supplied preassembled nanodiscs is possible. This chapter provides updated protocols for the synthesis of membrane proteins in presence of preassembled nanodiscs suitable for emerging applications such as screening of lipid effects on membrane protein function and the modulation of oligomeric complex formation.

Characterization of membrane association of Rinderpest virus matrix protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subhashri, R.; Shaila, M.S.

2007-04-20

Paramyxovirus matrix protein is believed to play a crucial role in the assembly and maturation of the virus particle by bringing the major viral components together at the budding site in the host cell. The membrane association capability of many enveloped virus matrix proteins has been characterized to be their intrinsic property. In this work, we have characterized the membrane association of Rinderpest virus matrix (M) protein. The M protein of Rinderpest virus when expressed in the absence of other viral proteins is present both in the cytoplasm and plasma membrane. When expressed as GFP fusion protein, the M proteinmore » gets localized into plasma membrane protrusions. High salt and alkaline conditions resulted in partial dissociation of M protein from cell membrane. Thus, M protein behaves like an integral membrane protein although its primary structure suggests it to be a peripheral membrane protein.« less

Proteomic Plasma Membrane Profiling Reveals an Essential Role for gp96 in the Cell Surface Expression of LDLR Family Members, Including the LDL Receptor and LRP6

PubMed Central

2012-01-01

The endoplasmic reticulum chaperone gp96 is required for the cell surface expression of a narrow range of proteins, including toll-like receptors (TLRs) and integrins. To identify a more comprehensive repertoire of proteins whose cell surface expression is dependent on gp96, we developed plasma membrane profiling (PMP), a technique that combines SILAC labeling with selective cell surface aminooxy-biotinylation. This approach allowed us to compare the relative abundance of plasma membrane (PM) proteins on gp96-deficient versus gp96-reconstituted murine pre-B cells. Analysis of unfractionated tryptic peptides initially identified 113 PM proteins, which extended to 706 PM proteins using peptide prefractionation. We confirmed a requirement for gp96 in the cell surface expression of certain TLRs and integrins and found a marked decrease in cell surface expression of four members of the extended LDL receptor family (LDLR, LRP6, Sorl1 and LRP8) in the absence of gp96. Other novel gp96 client proteins included CD180/Ly86, important in the B-cell response to lipopolysaccharide. We highlight common structural motifs in these client proteins that may be recognized by gp96, including the beta-propeller and leucine-rich repeat. This study therefore identifies the extended LDL receptor family as an important new family of proteins whose cell surface expression is regulated by gp96. PMID:22292497

Proteomic plasma membrane profiling reveals an essential role for gp96 in the cell surface expression of LDLR family members, including the LDL receptor and LRP6.

PubMed

Weekes, Michael P; Antrobus, Robin; Talbot, Suzanne; Hör, Simon; Simecek, Nikol; Smith, Duncan L; Bloor, Stuart; Randow, Felix; Lehner, Paul J

2012-03-02

The endoplasmic reticulum chaperone gp96 is required for the cell surface expression of a narrow range of proteins, including toll-like receptors (TLRs) and integrins. To identify a more comprehensive repertoire of proteins whose cell surface expression is dependent on gp96, we developed plasma membrane profiling (PMP), a technique that combines SILAC labeling with selective cell surface aminooxy-biotinylation. This approach allowed us to compare the relative abundance of plasma membrane (PM) proteins on gp96-deficient versus gp96-reconstituted murine pre-B cells. Analysis of unfractionated tryptic peptides initially identified 113 PM proteins, which extended to 706 PM proteins using peptide prefractionation. We confirmed a requirement for gp96 in the cell surface expression of certain TLRs and integrins and found a marked decrease in cell surface expression of four members of the extended LDL receptor family (LDLR, LRP6, Sorl1 and LRP8) in the absence of gp96. Other novel gp96 client proteins included CD180/Ly86, important in the B-cell response to lipopolysaccharide. We highlight common structural motifs in these client proteins that may be recognized by gp96, including the beta-propeller and leucine-rich repeat. This study therefore identifies the extended LDL receptor family as an important new family of proteins whose cell surface expression is regulated by gp96.

Prominin-2 expression increases protrusions, decreases caveolae and inhibits Cdc42 dependent fluid phase endocytosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Raman Deep, E-mail: Takhter.Ramandeep@mayo.edu; Schroeder, Andreas S.; Scheffer, Luana

Highlights: •Prominin-2 expression induced protrusions that co-localized with lipid raft markers. •Prominin-2 expression decreased caveolae, caveolar endocytosis and increased pCav1. •Prominin-2 expression inhibited fluid phase endocytosis by inactivation of Cdc42. •These endocytic effects can be reversed by adding exogenous cholesterol. •Caveolin1 knockdown restored fluid phase endocytosis in Prominin2 expressing cells. -- Abstract: Background: Membrane protrusions play important roles in biological processes such as cell adhesion, wound healing, migration, and sensing of the external environment. Cell protrusions are a subtype of membrane microdomains composed of cholesterol and sphingolipids, and can be disrupted by cholesterol depletion. Prominins are pentaspan membrane proteins thatmore » bind cholesterol and localize to plasma membrane (PM) protrusions. Prominin-1 is of great interest as a marker for stem and cancer cells, while Prominin-2 (Prom2) is reportedly restricted to epithelial cells. Aim: To characterize the effects of Prom-2 expression on PM microdomain organization. Methods: Prom2-fluorescent protein was transfected in human skin fibroblasts (HSF) and Chinese hamster ovary (CHO) cells for PM raft and endocytic studies. Caveolae at PM were visualized using transmission electron microscopy. Cdc42 activation was measured and caveolin-1 knockdown was performed using siRNAs. Results: Prom2 expression in HSF and CHO cells caused extensive Prom2-positive protrusions that co-localized with lipid raft markers. Prom2 expression significantly decreased caveolae at the PM, reduced caveolar endocytosis and increased caveolin-1 phosphorylation. Prom2 expression also inhibited Cdc42-dependent fluid phase endocytosis via decreased Cdc42 activation. Effects on endocytosis were reversed by addition of cholesterol. Knockdown of caveolin-1 by siRNA restored Cdc42 dependent fluid phase endocytosis in Prom2-expressing cells. Conclusions: Prom2 protrusions primarily localize to lipid rafts and recruit cholesterol into protrusions and away from caveolae, leading to increased phosphorylation of caveolin-1, which inhibits Cdc42-dependent endocytosis. This study provides a new insight for the role for prominins in the regulation of PM lipid organization.« less

Carbonic anhydrases in chick extra-embryonic structures: a role for CA in bicarbonate reabsorption through the chorioallantoic membrane.

PubMed

Gabrielli, M Gabriella

2004-06-01

The villus cavity cells, a specific cell type of the chick chorioallantoic membrane, express both cytosolic carbonic anhydrase in their cytoplasm and HCO3(-)/Cl(-) anion exchangers at their basolateral membranes. By immunohistochemical analysis, we show here that villus cavity cells specifically react with antibodies directed against the membrane-associated form of carbonic anhydrase, CAIV. Staining is restricted to the apical cell membranes, characteristically invaginated toward the shell membrane, as well as to endothelia of blood vessels present in the mesodermal layer. The occurrence of a membrane-associated CA form at the apical pole of villus cavity cells, when definitively confirmed, would be fairly consistent with the role proposed for these cells in bicarbonate reabsorption from the eggshell so to prevent metabolic acidosis in the embryo during development.

Paramyxovirus Glycoproteins and the Membrane Fusion Process.

PubMed

Aguilar, Hector C; Henderson, Bryce A; Zamora, J Lizbeth; Johnston, Gunner P

2016-09-01

The family Paramyxoviridae includes many viruses that significantly affect human and animal health. An essential step in the paramyxovirus life cycle is viral entry into host cells, mediated by virus-cell membrane fusion. Upon viral entry, infection results in expression of the paramyxoviral glycoproteins on the infected cell surface. This can lead to cell-cell fusion (syncytia formation), often linked to pathogenesis. Thus membrane fusion is essential for both viral entry and cell-cell fusion and an attractive target for therapeutic development. While there are important differences between viral-cell and cell-cell membrane fusion, many aspects are conserved. The paramyxoviruses generally utilize two envelope glycoproteins to orchestrate membrane fusion. Here, we discuss the roles of these glycoproteins in distinct steps of the membrane fusion process. These findings can offer insights into evolutionary relationships among Paramyxoviridae genera and offer future targets for prophylactic and therapeutic development.

Paramyxovirus Glycoproteins and the Membrane Fusion Process

PubMed Central

Aguilar, Hector C.; Henderson, Bryce A.; Zamora, J. Lizbeth; Johnston, Gunner P.

2016-01-01

The family Paramyxoviridae includes many viruses that significantly affect human and animal health. An essential step in the paramyxovirus life cycle is viral entry into host cells, mediated by virus-cell membrane fusion. Upon viral entry, infection results in expression of the paramyxoviral glycoproteins on the infected cell surface. This can lead to cell-cell fusion (syncytia formation), often linked to pathogenesis. Thus membrane fusion is essential for both viral entry and cell-cell fusion and an attractive target for therapeutic development. While there are important differences between viral-cell and cell-cell membrane fusion, many aspects are conserved. The paramyxoviruses generally utilize two envelope glycoproteins to orchestrate membrane fusion. Here, we discuss the roles of these glycoproteins in distinct steps of the membrane fusion process. These findings can offer insights into evolutionary relationships among Paramyxoviridae genera and offer future targets for prophylactic and therapeutic development. PMID:28138419

Expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) on prostate cancer cell lines.

PubMed

Nagakawa, O; Murakami, K; Yamaura, T; Fujiuchi, Y; Murata, J; Fuse, H; Saiki, I

2000-07-31

Membrane-type metalloproteinase-1 (MT1-MMP) is a transmembrane metalloproteinase, which activates proMMP-2 and expressed on the cell surface in many invasive cancer cells. We investigated the expression of MT1-MMP in prostate cancer cell lines. MT1-MMP protein and mRNA were expressed in PC-3, DU-145 and TSU-pr1 cells (androgen-independent prostate cancer cell lines), but in LNCaP cells (androgen-dependent prostate cancer cell line). MT1-MMP protein was negative and mRNA was low to detect by RT-PCR. Cell lysate of PC-3 cleaved proMMP-2 to the active form. In addition, both hepatocyte growth factor (HGF) and gastrin-releasing peptide (GRP) increased Matrigel invasion and induced the expression of MT1-MMP protein in DU-145 prostate cancer cells. These results suggest that MT1-MMP is indeed the tumor-specific activator of proMMP-2 in androgen-independent prostate cancer cells and plays an important role in the invasive properties of prostate cancer cells.

Expression of CD147 in advanced non-small cell lung cancer correlated with cisplatin-based chemotherapy resistance.

PubMed

Zeng, H Z; Qu, Y Q; Liang, A B; Deng, A M; Zhang, W J; Xiu, B; Wang, H; Wang, H

2011-01-01

CD147, a widely expressed cell surface glycoprotein in cancer, is associated with tumor invasiveness and chemotherapy resistance. Recently, CD147 is also regarded as a potential therapeutic target for cancer therapy. The aim of the study was to investigate CD147 expression in non-small cell lung cancer (NSCLC), and evaluate its correlation with cisplatin-based chemotherapy resistance. In this study, we examined immunohistochemically the expression of CD147 in 118 advanced NSCLC cases treated with cisplatin-based chemotherapy, and then the association of CD147 expression with clinicopathological characteristics was analyzed. Furthermore, RNA interference approach was used to silence CD147 expression in a cisplatin-resistant human lung cancer cell line A549/DDP, and the inhibition effect of cisplatin on tumor cells was assayed by MTT. In the overall series, positive CD147 expression was observed in 101/118 (85.6%) cases. A membranous CD147 pattern was identified in 76/101 (75.2%) of CD147 positive tumors. CD147 membranous expression,but not the overall CD147 expression, was associated with poor response to cisplatin-based chemotherapies and a poor prognosis in advanced NSCLC patients. In vitro results showed that silencing CD147 increased the proliferation inhibitory effect of cisplatin to A549/DDP cells. In conclusion, our study indicated that membranous CD147 expression is a predictive factor of the response to cisplatin-based chemotherapies, and the use of CD147-targeted therapeutic adjuvants might be considered in the treatment of advanced NSCLC patients.

Prostate specific membrane antigen (PSMA) expression in non-small cell lung cancer

PubMed Central

Heitkötter, Birthe; Schulze, Arik B.; Schliemann, Christoph; Steinestel, Konrad; Trautmann, Marcel; Marra, Alessandro; Hillejan, Ludger; Mohr, Michael; Evers, Georg; Wardelmann, Eva; Rahbar, Kambiz; Görlich, Dennis; Lenz, Georg; Berdel, Wolfgang E.; Hartmann, Wolfgang; Wiewrodt, Rainer; Huss, Sebastian

2017-01-01

Objectives PSMA (prostate-specific membrane antigen) is overexpressed in prostate cancer cells and is reported to be a promising target for antibody-based radioligand therapy in patients with metastasized prostate cancer. Since PSMA expression is not restricted to prostate cancer, the underlying study investigates PSMA expression in non-small cell lung cancer (NSCLC). Material and methods Immunohistochemistry was used to identify PSMA expression in n = 275 samples of NSCLC tissue specimens. By means of CD34 co-expression, the level of PSMA expression in tumor associated neovasculature was investigated. The impact of PSMA expression on clinicopathologic parameters and prognosis was evaluated. Results PSMA tumor cell expression in NSCLC is as low as 6% and was predominantly found in squamous cell carcinoma (p = 0.002). Neovascular PSMA expression was found in 49% of NSCLC. High neovascular PSMA expression was associated with higher tumor grading (G3/G4) (p < 0.001). Neither for PSMA tumor cell expression, nor for PSMA neovascular cell expression prognostic effects were found for the investigated NSCLC cases. Conclusion Here, we report on the expression of PSMA in NSCLC tissue samples. Against the background of a potential treatment with radiolabeled PSMA ligands, our data might serve for the future identification of patients who could benefit from this therapeutic option. PMID:29077706

Production of functional bacteriorhodopsin by an Escherichia coli cell-free protein synthesis system supplemented with steroid detergent and lipid.

PubMed

Shimono, Kazumi; Goto, Mie; Kikukawa, Takashi; Miyauchi, Seiji; Shirouzu, Mikako; Kamo, Naoki; Yokoyama, Shigeyuki

2009-10-01

Cell-free expression has become a highly promising tool for the efficient production of membrane proteins. In this study, we used a dialysis-based Escherichia coli cell-free system for the production of a membrane protein actively integrated into liposomes. The membrane protein was the light-driven proton pump bacteriorhodopsin, consisting of seven transmembrane alpha-helices. The cell-free expression system in the dialysis mode was supplemented with a combination of a detergent and a natural lipid, phosphatidylcholine from egg yolk, in only the reaction mixture. By examining a variety of detergents, we found that the combination of a steroid detergent (digitonin, cholate, or CHAPS) and egg phosphatidylcholine yielded a large amount (0.3-0.7 mg/mL reaction mixture) of the fully functional bacteriorhodopsin. We also analyzed the process of functional expression in our system. The synthesized polypeptide was well protected from aggregation by the detergent-lipid mixed micelles and/or lipid disks, and was integrated into liposomes upon detergent removal by dialysis. This approach might be useful for the high yield production of functional membrane proteins.

Cholesterol depletion in cell membranes of human airway epithelial cells suppresses MUC5AC gene expression.

PubMed

Song, Kee Jae; Kim, Na Hyun; Lee, Gi Bong; Kim, Ji Hoon; Kwon, Jin Ho; Kim, Kyung-Su

2013-05-01

If cholesterol in the cell membrane is depleted by treating cells with methyl-β-cyclodextrin (MβCD), the activities of transmembrane receptors are altered in a cell-specific and/or receptor-specific manner. The proinflammatory cytokines, IL-1β is potent inducers of MUC5AC mRNA and protein synthesis in human airway epithelial cells. Cells activated by IL-1β showed increased phosphorylation of extracellular signal regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). Thus, we investigated the effects of cholesterol depletion on the expression of MUC5AC in human airway epithelial cells and whether these alterations to MUC5AC expression were related to MAPK activity. After NCI-H292 cells were pretreated with 1% MβCD before adding IL-1β for 24 hours, MUC5AC mRNA expression was determined by reverse transcription- polymerase chain reaction (RT-PCR) and real time-PCR. Cholesterol depletion by MβCD was measured by modified microenzymatic fluorescence assay and filipin staining. The phosphorylation of IL-1 receptor, ERK and p38 MAPK, was analyzed by western blot. Cholesterol in the cell membrane was significantly depleted by treatment with MβCD on cells. IL-1β-induced MUC5AC mRNA expression was decreased by MβCD and this decrease occurred IL-1-receptor- specifically. Moreover, we have shown that MβCD suppressed the activation of ERK1/2 and p38 MAPK in cells activated with IL-1β. This result suggests that MβCD-mediated suppression of IL-1β-induced MUC5AC mRNA operated via the ERK- and p38 MAPK-dependent pathway. Cholesterol depletion in NCI-H292 cell membrane may be considered an anti-hypersecretory method since it effectively inhibits mucus secretion of respiratory epithelial cells.

Regulation of surface expression of TRPV2 channels in the retinal pigment epithelium.

PubMed

Reichhart, Nadine; Keckeis, Susanne; Fried, Frederik; Fels, Gabriele; Strauss, Olaf

2015-06-01

The retinal pigment epithelium (RPE) interacts closely with the photoreceptors in fulfilling tasks of visual function. Since an understanding of the RPE function is essential for understanding the patho-mechanisms involved in vision loss, we explored the regulation of the vanilloid receptor subtype transient receptor potential TRPV2 channels that trigger insulin-like growth factor-1 (IGF-1)-induced vascular endothelial growth factor A (VEGF-A) secretion. Immunohistochemistry was used to assess TRPV2 expression in retinal cross-sections or ARPE-19 cells, and surface expression of TRPV2 was quantified using confocal microscopy. Membrane currents of ARPE-19 cells were recorded using a whole-cell configuration of the patch-clamp technique. TRPV2 expression was detected in the RPE of the mouse retina as well as in ARPE-19 cells. Increasing the temperature to 45 °C activated membrane conductance sensitive to SKF-96365 and ruthenium red in 60 % of cells. Preincubation with either cannabidiol (CBD) or IGF-1 led to a three- or fourfold increase in current density, respectively, in all cells, which was blocked by SKF-96365. In contrast to IGF-1, CBD stimulation of membrane conductance was further increased by heat. TRPV2 surface expression was increased by both IGF-1 and CBD, with the increase by CBD twice as large as that by IGF-1. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 abolished the effects on membrane conductance and surface expression. Both CBD and IGF-1 enhance TRPV2 channel activity by specific proportions of both channel activation and PI 3-kinase-dependent surface expression: IGF-1 predominantly increases ion channel activity, whereas CBD is more active in increasing TRPV2 surface expression. Thus, differential regulation of TRPV2 surface expression is an important mechanism for modulating the responsiveness of the RPE to growth factors.

ATP-binding cassette transporters are enriched in non-caveolar detergent-insoluble glycosphingolipid-enriched membrane domains (DIGs) in human multidrug-resistant cancer cells.

PubMed

Hinrichs, John W J; Klappe, Karin; Hummel, Ina; Kok, Jan W

2004-02-13

In this study we show that P-glycoprotein in multidrug-resistant 2780AD human ovarian carcinoma cells and multidrug resistance-associated protein 1 in multidrug-resistant HT29col human colon carcinoma cells are predominantly located in Lubrol-based detergent-insoluble glycosphingolipid-enriched membrane domains. This localization is independent of caveolae, since 2780AD cells do not express caveolin-1. Although HT29col cells do express caveolin-1, the ATP-binding cassette transporter and caveolin-1 were dissociated on the basis of differential solubility in Triton X-100 and absence of microscopical colocalization. While both the multidrug resistance-associated protein 1 and caveolin-1 are located in Lubrol-based membrane domains, they occupy different regions of these domains.

Altered expression of CD1d molecules and lipid accumulation in the human hepatoma cell line HepG2 after iron loading.

PubMed

Cabrita, Marisa; Pereira, Carlos F; Rodrigues, Pedro; Cardoso, Elsa M; Arosa, Fernando A

2005-01-01

Iron overload in the liver may occur in clinical conditions such as hemochromatosis and nonalcoholic steatohepatitis, and may lead to the deterioration of the normal liver architecture by mechanisms not well understood. Although a relationship between the expression of ICAM-1, and classical major histocompatibility complex (MHC) class I molecules, and iron overload has been reported, no relationship has been identified between iron overload and the expression of unconventional MHC class I molecules. Herein, we report that parameters of iron metabolism were regulated in a coordinated-fashion in a human hepatoma cell line (HepG2 cells) after iron loading, leading to increased cellular oxidative stress and growth retardation. Iron loading of HepG2 cells resulted in increased expression of Nor3.2-reactive CD1d molecules at the plasma membrane. Expression of classical MHC class I and II molecules, ICAM-1 and the epithelial CD8 ligand, gp180 was not significantly affected by iron. Considering that intracellular lipids regulate expression of CD1d at the cell surface, we examined parameters of lipid metabolism in iron-loaded HepG2 cells. Interestingly, increased expression of CD1d molecules by iron-loaded HepG2 cells was associated with increased phosphatidylserine expression in the outer leaflet of the plasma membrane and the presence of many intracellular lipid droplets. These data describe a new relationship between iron loading, lipid accumulation and altered expression of CD1d, an unconventional MHC class I molecule reported to monitor intracellular and plasma membrane lipid metabolism, in the human hepatoma cell line HepG2.

Comparative proteomic analysis reveals a dynamic pollen plasma membrane protein map and the membrane landscape of receptor-like kinases and transporters important for pollen tube growth and interaction with pistils in rice.

PubMed

Yang, Ning; Wang, Tai

2017-01-05

The coordination of pollen tube (PT) growth, guidance and timely growth arrest and rupture mediated by PT-pistil interaction is crucial for the PT to transport sperm cells into ovules for double fertilization. The plasma membrane (PM) represents an important interface for cell-cell interaction, and PM proteins of PTs are pioneers for mediating PT integrity and interaction with pistils. Thus, understanding the mechanisms underlying these events is important for proteomics. Using the efficient aqueous polymer two-phase system and alkali buffer treatment, we prepared high-purity PM from mature and germinated pollen of rice. We used iTRAQ quantitative proteomic methods and identified 1,121 PM-related proteins (PMrPs) (matched to 899 loci); 192 showed differential expression in the two pollen cell types, 119 increased and 73 decreased in abundance during germination. The PMrP and differentially expressed PMrP sets all showed a functional skew toward signal transduction, transporters, wall remodeling/metabolism and membrane trafficking. Their genomic loci had strong chromosome bias. We found 37 receptor-like kinases (RLKs) from 8 kinase subfamilies and 209 transporters involved in flux of diversified ions and metabolites. In combination with the rice pollen transcriptome data, we revealed that in general, the protein expression of these PMrPs disagreed with their mRNA expression, with inconsistent mRNA expression for 74% of differentially expressed PMrPs. This study identified genome-wide pollen PMrPs, and provided insights into the membrane profile of receptor-like kinases and transporters important for pollen tube growth and interaction with pistils. These pollen PMrPs and their mRNAs showed discordant expression. This work provides resource and knowledge to further dissect mechanisms by which pollen or the PT controls PMrP abundance and monitors interactions and ion and metabolite exchanges with female cells in rice.

Role of Pgrmc1 in estrogen maintenance of meiotic arrest in zebrafish oocytes through Gper/Egfr.

PubMed

Aizen, Joseph; Thomas, Peter

2015-04-01

The regulation of receptor trafficking to the cell surface and its effect on responses of target cells to growth factors and hormones remain poorly understood. Initial evidence has been recently obtained using cancer cells that surface expression of the epidermal growth factor receptor (EGFR) is dependent on its association with progesterone receptor membrane component 1 (PGRMC1). Estrogen inhibition of oocyte maturation (OM) in zebrafish is mediated through G-protein-coupled estrogen membrane receptor 1 (Gper1) and involves activation of Egfr. Therefore, in this study, the potential roles of Pgrmc1 in the cell surface expression and functions of Egfr in normal cells were investigated in this in vitro OM model of Egfr action using an inhibitor of PGMRC1 signaling, AG205. A single ∼60 kDa protein band, which corresponds to the size of the Pgrmc1 dimer, was detected on plasma membranes of fully grown oocytes by western blotting. Co-treatment with the PGRMC1 inhibitor AG205 (20 μM) blocked the inhibitory effects of 100 nM estradiol-17β and the GPER agonist, G-1, on spontaneous maturation of denuded zebrafish oocytes. Moreover, reversal of these estrogen effects on OM by the EGFR inhibitors AG1478 and AG825 (50 μM) was prevented by co-incubation with the PGRMC1 inhibitor. Inhibition of Pgrmc1 signaling with AG205 also caused a decrease in Egfr-dependent signaling and Egfr expression on oocyte cell membranes. These results indicate that maintenance of Pgrmc1 signaling is required for Egfr expression on zebrafish oocyte cell membranes and for conserving the functions of Egfr in maintaining meiotic arrest through estrogen activation of Gper. © 2015 Society for Endocrinology.

Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth

PubMed Central

Jackson, William F.

2017-01-01

Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+ and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. Vascular smooth muscle cells express multiple isoforms of at least five classes of K+ channels contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression and function of large-conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells. PMID:28212804

Placental membrane aging and HMGB1 signaling associated with human parturition

PubMed Central

Menon, Ramkumar; Behnia, Faranak; Polettini, Jossimara; Saade, George R; Campisi, Judith; Velarde, Michael

2016-01-01

Aging is associated with the onset of several diseases in various organ systems; however, different tissues may age differently, rendering some of them dysfunctional sooner than others. Placental membranes (fetal amniochorionic membranes) protect the fetus throughout pregnancy, but their longevity is limited to the duration of pregnancy. The age-associated dysfunction of these membranes is postulated to trigger parturition. Here, we investigated whether cellular senescence—the loss of cell division potential as a consequence of stress—is involved in placental membrane function at term. We show telomere reduction, p38 MAPK activation, increase in p21 expression, loss of lamin B1 loss, increase in SA-β-galactosidase, and senescence-associated secretory phenotype (SASP) gene expression in placental membranes after labor and delivery (term labor [TL]) compared to membranes prior to labor at term (term, not-in-labor [TNIL]). Exposing TNIL placental membranes to cigarette smoke extract, an oxidative stress inducer, also induced markers of cellular senescence similar to those in TL placental membranes. Bioinformatics analysis of differentially expressed SASP genes revealed HMGB1 signaling among the top pathways involved in labor. Further, we show that recombinant HMGB1 upregulates the expression of genes associated with parturition in myometrial cells. These data suggest that the natural physiologic aging of placental tissues is associated with cellular senescence and human parturition. PMID:26851389

{beta}-Catenin regulates airway smooth muscle contraction.

PubMed

Jansen, Sepp R; Van Ziel, Anna M; Baarsma, Hoeke A; Gosens, Reinoud

2010-08-01

beta-Catenin is an 88-kDa member of the armadillo family of proteins that is associated with the cadherin-catenin complex in the plasma membrane. This complex interacts dynamically with the actin cytoskeleton to stabilize adherens junctions, which play a central role in force transmission by smooth muscle cells. Therefore, in the present study, we hypothesized a role for beta-catenin in the regulation of smooth muscle force production. beta-Catenin colocalized with smooth muscle alpha-actin (sm-alpha-actin) and N-cadherin in plasma membrane fractions and coimmunoprecipitated with sm-alpha-actin and N-cadherin in lysates of bovine tracheal smooth muscle (BTSM) strips. Moreover, immunocytochemistry of cultured BTSM cells revealed clear and specific colocalization of sm-alpha-actin and beta-catenin at the sites of cell-cell contact. Treatment of BTSM strips with the pharmacological beta-catenin/T cell factor-4 (TCF4) inhibitor PKF115-584 (100 nM) reduced beta-catenin expression in BTSM whole tissue lysates and in plasma membrane fractions and reduced maximal KCl- and methacholine-induced force production. These changes in force production were not accompanied by changes in the expression of sm-alpha-actin or sm-myosin heavy chain (MHC). Likewise, small interfering RNA (siRNA) knockdown of beta-catenin in BTSM strips reduced beta-catenin expression and attenuated maximal KCl- and methacholine-induced contractions without affecting sm-alpha-actin or sm-MHC expression. Conversely, pharmacological (SB-216763, LiCl) or insulin-induced inhibition of glycogen synthase kinase-3 (GSK-3) enhanced the expression of beta-catenin and augmented maximal KCl- and methacholine-induced contractions. We conclude that beta-catenin is a plasma membrane-associated protein in airway smooth muscle that regulates active tension development, presumably by stabilizing cell-cell contacts and thereby supporting force transmission between neighboring cells.

Prognostic value of CD44 expression in penile squamous cell carcinoma: a pilot study.

PubMed

Minardi, Daniele; Lucarini, Guendalina; Filosa, Alessandra; Zizzi, Antonio; Simonetti, Oriana; Offidani, Anna Maria; d'Anzeo, Gianluca; Di Primio, Roberto; Montironi, Rodolfo; Muzzonigro, Giovanni

2012-10-01

Several studies have reported on the prognostic value of molecular markers for metastasis risk and survival in penile squamous cell carcinoma (SCC) patients. The usefulness of CD44 expression as such a marker has been studied in different tumors, but not in penile SCC. Our aim was to determine whether CD44 expression may serve as a prognostic marker for lymph node metastasis and survival in penile SCC patients. CD44 immunoistochemical expression was investigated in tissue specimens from 39 patients with penile SCC. CD44 cell positivity, staining intensity and distribution were analyzed and correlated with tumor stage, grade, lymph node status and disease-specific survival. CD44 expression was detected in epithelial cells of both intratumoral and normal tissues with different intensities and staining distributions. In normal tissues CD44 protein was mainly detected in cell membranes, whereas in the tumor compartments it was found in both the cell membranes and the cytoplasm. The intensities and percentages of CD44 expressing cells did not correlate with tumor stage and/or grade. Seventy-three percent of the patients with lymph node metastasis showed high intensities of CD44 staining, as compared to 44% of the patients without lymph node metastasis (P = 0.03). Lymph node-positive patients showed both cytoplasmic and membranous CD44 expression. High CD44 expression was found to be significantly correlated with a decreased 5 year overall survival (P = 0.01). CD44 levels and patterns of expression can be considered as markers for penile SCC aggressiveness and, in addition, may serve as predictive markers for lymph node metastasis, also in patients with clinically negative lymph nodes. CD44 expression may provide prognostic information for penile SCC patients, next to classical clinical-pathological factors.

Wheat germ cell-free expression: Two detergents with a low critical micelle concentration allow for production of soluble HCV membrane proteins.

PubMed

Fogeron, Marie-Laure; Badillo, Aurélie; Jirasko, Vlastimil; Gouttenoire, Jérôme; Paul, David; Lancien, Loick; Moradpour, Darius; Bartenschlager, Ralf; Meier, Beat H; Penin, François; Böckmann, Anja

2015-01-01

Membrane proteins are notoriously difficult to express in a soluble form. Here, we use wheat germ cell-free expression in the presence of various detergents to produce the non-structural membrane proteins 2, 4B and 5A of the hepatitis C virus (HCV). We show that lauryl maltose neopentyl glycol (MNG-3) and dodecyl octaethylene glycol ether (C12E8) detergents can yield essentially soluble membrane proteins at detergent concentrations that do not inhibit the cell-free reaction. This finding can be explained by the low critical micelle concentration (CMC) of these detergents, which keeps the monomer concentrations low while at the same time providing the necessary excess of detergent concentration above CMC required for full target protein solubilization. We estimate that a tenfold excess of detergent micelles with respect to the protein concentration is sufficient for solubilization, a number that we propose as a guideline for detergent screening assays. Copyright © 2014 Elsevier Inc. All rights reserved.

Phospholipase D1 regulates lymphocyte adhesion via upregulation of Rap1 at the plasma membrane.

PubMed

Mor, Adam; Wynne, Joseph P; Ahearn, Ian M; Dustin, Michael L; Du, Guangwei; Philips, Mark R

2009-06-01

Rap1 is a small GTPase that modulates adhesion of T cells by regulating inside-out signaling through LFA-1. The bulk of Rap1 is expressed in a GDP-bound state on intracellular vesicles. Exocytosis of these vesicles delivers Rap1 to the plasma membrane, where it becomes activated. We report here that phospholipase D1 (PLD1) is expressed on the same vesicular compartment in T cells as Rap1 and is translocated to the plasma membrane along with Rap1. Moreover, PLD activity is required for both translocation and activation of Rap1. Increased T-cell adhesion in response to stimulation of the antigen receptor depended on PLD1. C3G, a Rap1 guanine nucleotide exchange factor located in the cytosol of resting cells, translocated to the plasma membranes of stimulated T cells. Our data support a model whereby PLD1 regulates Rap1 activity by controlling exocytosis of a stored, vesicular pool of Rap1 that can be activated by C3G upon delivery to the plasma membrane.

[Bioactive glass 45S5-silk fibroin membrane supports proliferation and differentiation of human dental pulp stem cells].

PubMed

Lyu, Xiaoshuai; Li, Zhengmao; Wang, Haiyan; Yang, Xuechao

2015-12-01

To investigate the effect of bioactivity glass 45S5- silk fibroin(BG45S5- SF) membrane on growth, proliferation and differentiation of human dental pulp stem cells(hDPSC), and to provide new ideas and method for the regeneration of pulp-dentine complex. hDPSC seed on pure silk fibroin membrane (protein membrane group) and BG45S5-SF membrane with different concentrations(1 000, 5 000 mg/L, composite membrane group A and B, respectively) were prepared, and the materials were incubated in cell culture fluid for 24 h. No material membrane orifice plate was used as blank control group. Contact angle meter was used to measure surface contact angle of protein membrane and composite membrane group(each group had three repeated holes). Cell proliferation was assessed by cell counting kit- 8 on the 4, 7, 14, and 21 days. The state of adhesion and growth of hDPSC on the materials surface was evaluated by scanning electron microscopy and cytoskeleton staining; and alkaline phosphatase (ALP) activity was measured to evaluate the cell differentiation potential. The expression of odontoblastic differentiation-related genes was measured by real-time PCR. Surface contact angle of the protein membrane group and composite membrane group A and group B were 89.51° ± 0.12°, 70.32° ± 0.07° and 71.31° ± 0.09° respectively. hDPSC adhered well on each materials surface on the 7, 14, 21 days, ALP activity and differentiation genes of composite membrane group A and B rised more significantly than the blank control group and protein membrane group did (P<0.05). Dentin matrix protein1(DMP- 1), dentin sialoprotein(DSP), ALP, osteocalcin(OC) mRNA expression reached peak on the 14 days in group A, and in group B on the 21 days. Bone sialoprotein(BSP) mRNA expression in both group A and B reached peak on the 21 days. BG45S5- SF membrane is able to support the proliferation and showed the potential of odontoblastic differentiation for hDPSC. This finding suggests that BG45S5-SF membrane was a kind of tissue engineering film material with the regeneration potential for pulp-dentine complex.

Expression pattern of immunosurveillance-related antigen in adult T cell leukaemia/lymphoma.

PubMed

Asano, Naoko; Miyoshi, Hiroaki; Kato, Takeharu; Shimono, Joji; Yoshida, Noriaki; Kurita, Daisuke; Sasaki, Yuya; Kawamoto, Keisuke; Ohshima, Koichi; Seto, Masao

2018-05-01

Adult T cell leukaemia/lymphoma (ATLL) is an aggressive malignancy with a poor prognosis. Human leucocyte antigen (HLA) and β2 microglobulin (β2M) serve as key molecules in tumour immunity, and their expression is reduced frequently in tumour cells. Programmed cell death (PD)-1/PD-ligand1 (PD-L1) interactions play a role in escape of tumour cells from T cell immunity. Therefore, this study aimed to determine the clinicopathological relevance of HLA and β2M expressions in ATLL cells and PD-L1 expression in lymphoma or stromal cells and predict the overall survival of patients with ATLL. We analysed a total of 123 biopsy samples from patients newly diagnosed with ATLL by using immunohistochemical analysis. Of the patients enrolled, 91 (74%) were positive for HLA (in cell membrane, 60 patients), 89 (72%) were positive for β2M (in cell membrane, 54 patients) and 48 (39%) were positive for both HLA and β2M in the cell membrane (HLA m+ β2M m+ ). No significant clinical differences other than prognosis were found between the HLA m+ β2M m+ group and the other groups. Immunophenotypical evaluation revealed significantly higher rates of CD30-positive lymphoma cells (P = 0.003) and PD-L1-positive stromal cells in microenvironments (miPD-L1 high ) (P = 0.011) of the HLA m+ β2M m+ group than in the other groups. The HLA m+ β2M m+ group had a significantly better prognosis that the other groups (P = 0.0096), and patients showing HLA m+ β2M m+ with miPD-L1 high had the most favourable prognosis among all groups. The membranous expression of HLA and β2M is likely to reflect the immune response and would be useful to predict prognosis before starting ATLL therapy. © 2018 John Wiley & Sons Ltd.

Screening and large-scale expression of membrane proteins in mammalian cells for structural studies

PubMed Central

Goehring, April; Lee, Chia-Hsueh; Wang, Kevin H.; Michel, Jennifer Carlisle; Claxton, Derek P.; Baconguis, Isabelle; Althoff, Thorsten; Fischer, Suzanne; Garcia, K. Christopher; Gouaux, Eric

2014-01-01

Structural, biochemical and biophysical studies of eukaryotic membrane proteins are often hampered by difficulties in over-expression of the candidate molecule. Baculovirus transduction of mammalian cells (BacMam), although a powerful method to heterologously express membrane proteins, can be cumbersome for screening and expression of multiple constructs. We therefore developed plasmid Eric Gouaux (pEG) BacMam, a vector optimized for use in screening assays, as well as for efficient production of baculovirus and robust expression of the target protein. In this protocol we show how to use small-scale transient transfection and fluorescence-detection, size-exclusion chromatography (FSEC) experiments using a GFP-His8 tagged candidate protein to screen for monodispersity and expression level. Once promising candidates are identified, we describe how to generate baculovirus, transduce HEK293S GnTI− (N-acetylglucosaminyltransferase I-negative) cells in suspension culture, and over-express the candidate protein. We have used these methods to prepare pure samples of chicken acid-sensing ion channel 1a (cASIC1) and Caenorhabditis elegans glutamate-gated chloride channel (GluCl), for X-ray crystallography, demonstrating how to rapidly and efficiently screen hundreds of constructs and accomplish large-scale expression in 4-6 weeks. PMID:25299155

Activation of the novel estrogen receptor G protein-coupled receptor 30 (GPR30) at the plasma membrane.

PubMed

Filardo, E; Quinn, J; Pang, Y; Graeber, C; Shaw, S; Dong, J; Thomas, P

2007-07-01

G protein-coupled receptor 30 (GPR30), a seven-transmembrane receptor (7TMR), is associated with rapid estrogen-dependent, G protein signaling and specific estrogen binding. At present, the subcellular site of GPR30 action is unclear. Previous studies using antibodies and fluorochrome-labeled estradiol (E2) have failed to detect GPR30 on the cell surface, suggesting that GPR30 may function uniquely among 7TMRs as an intracellular receptor. Here, we show that detectable expression of GPR30 on the surface of transfected HEK-293 cells can be selected by fluorescence-activated cell sorting. Expression of GPR30 on the cell surface was confirmed by confocal microscopy using the lectin concanavalin A as a plasma membrane marker. Stimulation of GPR30-expressing HEK-293 cells with 17beta-E2 caused sequestration of GPR30 from the cell surface and resulted in its codistribution with clathrin and mobilization of intracellular calcium stores. Evidence that GPR30 signals from the cell surface was obtained from experiments demonstrating that the cell-impermeable E2-protein conjugates E2-BSA and E2-horseradish peroxidase promote GPR30-dependent elevation of intracellular cAMP concentrations. Subcellular fractionation studies further support the plasma membrane as a site of GPR30 action with specific [3H]17beta-E2 binding and G protein activation associated with plasma membrane but not microsomal, or other fractions, prepared from HEK-293 or SKBR3 breast cancer cells. These results suggest that GPR30, like other 7TMRs, functions as a plasma membrane receptor.

Improving membrane protein expression and function using genomic edits

DOE PAGES

Jensen, Heather M.; Eng, Thomas; Chubukov, Victor; ...

2017-10-12

Expression of membrane proteins often leads to growth inhibition and perturbs central metabolism and this burden varies with the protein being overexpressed. There are also known strain backgrounds that allow greater expression of membrane proteins but that differ in efficacy across proteins. Here, we hypothesized that for any membrane protein, it may be possible to identify a modified strain background where its expression can be accommodated with less burden. To directly test this hypothesis, we used a bar-coded transposon insertion library in tandem with cell sorting to assess genome-wide impact of gene deletions on membrane protein expression. The expression ofmore » five membrane proteins (CyoB, CydB, MdlB, YidC, and LepI) and one soluble protein (GST), each fused to GFP, was examined. We identified Escherichia coli mutants that demonstrated increased membrane protein expression relative to that in wild type. For two of the proteins (CyoB and CydB), we conducted functional assays to confirm that the increase in protein expression also led to phenotypic improvement in function. This study represents a systematic approach to broadly identify genetic loci that can be used to improve membrane protein expression, and our method can be used to improve expression of any protein that poses a cellular burden.« less

Improving membrane protein expression and function using genomic edits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, Heather M.; Eng, Thomas; Chubukov, Victor

Expression of membrane proteins often leads to growth inhibition and perturbs central metabolism and this burden varies with the protein being overexpressed. There are also known strain backgrounds that allow greater expression of membrane proteins but that differ in efficacy across proteins. Here, we hypothesized that for any membrane protein, it may be possible to identify a modified strain background where its expression can be accommodated with less burden. To directly test this hypothesis, we used a bar-coded transposon insertion library in tandem with cell sorting to assess genome-wide impact of gene deletions on membrane protein expression. The expression ofmore » five membrane proteins (CyoB, CydB, MdlB, YidC, and LepI) and one soluble protein (GST), each fused to GFP, was examined. We identified Escherichia coli mutants that demonstrated increased membrane protein expression relative to that in wild type. For two of the proteins (CyoB and CydB), we conducted functional assays to confirm that the increase in protein expression also led to phenotypic improvement in function. This study represents a systematic approach to broadly identify genetic loci that can be used to improve membrane protein expression, and our method can be used to improve expression of any protein that poses a cellular burden.« less

Rapid Preparation of a Plasma Membrane Fraction: Western Blot Detection of Translocated Glucose Transporter 4 from Plasma Membrane of Muscle and Adipose Cells and Tissues.

PubMed

Yamamoto, Norio; Yamashita, Yoko; Yoshioka, Yasukiyo; Nishiumi, Shin; Ashida, Hitoshi

2016-08-01

Membrane proteins account for 70% to 80% of all pharmaceutical targets, indicating their clinical relevance and underscoring the importance of identifying differentially expressed membrane proteins that reflect distinct disease properties. The translocation of proteins from the bulk of the cytosol to the plasma membrane is a critical step in the transfer of information from membrane-embedded receptors or transporters to the cell interior. To understand how membrane proteins work, it is important to separate the membrane fraction of cells. This unit provides a protocol for rapidly obtaining plasma membrane fractions for western blot analysis. © 2016 by John Wiley & Sons, Inc. Copyright © 2016 John Wiley & Sons, Inc.

Dysregulated expression of cell surface glycoprotein CDCP1 in prostate cancer

PubMed Central

Yang, Lifang; Dutta, Sucharita M.; Troyer, Dean A.; Lin, Jefferson B.; Lance, Raymond A.; Nyalwidhe, Julius O.; Drake, Richard R; Semmes, O. John

2015-01-01

CUB-domain-containing protein 1 (CDCP1) is a trans-membrane protein regulator of cell adhesion with a potent pro-migratory function in tumors. Given that proteolytic cleavage of the ectodomain correlates with outside-in oncogenic signaling, we characterized glycosylation in the context of cellular processing and expression of CDCP1 in prostate cancer. We detected 135 kDa full-length and proteolytic processed 70 kDa species in a panel of PCa cell models. The relative expression of full-length CDCP1 correlated with the metastatic potential of syngeneic cell models and an increase in surface membrane expression of CDCP1 was observed in tumor compared to adjacent normal prostate tissues. We demonstrated that glycosylation of CDCP1 is a prerequisite for protein stability and plasma membrane localization, and that the expression level and extent of N-glycosylation of CDCP1 correlated with metastatic status. Interestingly, complex N-linked glycans with sialic acid chains were restricted to the N-terminal half of the ectodomain and absent in the truncated species. Characterization of the extracellular expression of CDCP1 identified novel circulating forms and revealed that extracellular vesicles provide additional processing pathways. Employing immunoaffinity mass spectrometry, we detected elevated levels of circulating CDCP1 in patient urine with high-risk disease. Our results establish that differential glycosylation, cell surface presentation and extracellular expression of CDCP1 are hallmarks of PCa progression. PMID:26497208

The cyclic nucleotide gated cation channel AtCNGC10 traffics from the ER via Golgi vesicles to the plasma membrane of Arabidopsis root and leaf cells.

PubMed

Christopher, David A; Borsics, Tamas; Yuen, Christen Y L; Ullmer, Wendy; Andème-Ondzighi, Christine; Andres, Marilou A; Kang, Byung-Ho; Staehelin, L Andrew

2007-09-19

The cyclic nucleotide-gated ion channels (CNGCs) maintain cation homeostasis essential for a wide range of physiological processes in plant cells. However, the precise subcellular locations and trafficking of these membrane proteins are poorly understood. This is further complicated by a general deficiency of information about targeting pathways of membrane proteins in plants. To investigate CNGC trafficking and localization, we have measured Atcngc5 and Atcngc10 expression in roots and leaves, analyzed AtCNGC10-GFP fusions transiently expressed in protoplasts, and conducted immunofluorescence labeling of protoplasts and immunoelectron microscopic analysis of high pressure frozen leaves and roots. AtCNGC10 mRNA and protein levels were 2.5-fold higher in roots than leaves, while AtCNGC5 mRNA and protein levels were nearly equal in these tissues. The AtCNGC10-EGFP fusion was targeted to the plasma membrane in leaf protoplasts, and lightly labeled several intracellular structures. Immunofluorescence microscopy with affinity purified CNGC-specific antisera indicated that AtCNGC5 and AtCNGC10 are present in the plasma membrane of protoplasts. Immunoelectron microscopy demonstrated that AtCNGC10 was associated with the plasma membrane of mesophyll, palisade parenchyma and epidermal cells of leaves, and the meristem, columella and cap cells of roots. AtCNCG10 was also observed in the endoplasmic reticulum and Golgi cisternae and vesicles of 50-150 nm in size. Patch clamp assays of an AtCNGC10-GFP fusion expressed in HEK293 cells measured significant cation currents. AtCNGC5 and AtCNGC10 are plasma membrane proteins. We postulate that AtCNGC10 traffics from the endoplasmic reticulum via the Golgi apparatus and associated vesicles to the plasma membrane. The presence of the cation channel, AtCNGC10, in root cap meristem cells, cell plate, and gravity-sensing columella cells, combined with the previously reported antisense phenotypes of decreased gravitropic and cell enlargement responses, suggest roles of AtCNGC10 in modulating cation balance required for root gravitropism, cell division and growth.

Detection of cholesterol-rich microdomains in the inner leaflet of the plasma membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, Masami; Shimada, Yukiko; Inomata, Mitsushi

2006-12-22

The C-terminal domain (D4) of perfringolysin O binds selectively to cholesterol in cholesterol-rich microdomains. To address the issue of whether cholesterol-rich microdomains exist in the inner leaflet of the plasma membrane, we expressed D4 as a fusion protein with EGFP in MEF cells. More than half of the EGFP-D4 expressed in stable cell clones was bound to membranes in raft fractions. Depletion of membrane cholesterol with {beta}-cyclodextrin reduced the amount of EGFP-D4 localized in raft fractions, confirming EGFP-D4 binding to cholesterol-rich microdomains. Subfractionation of the raft fractions showed most of the EGFP-D4 bound to the plasma membrane rather than tomore » intracellular membranes. Taken together, these results strongly suggest the existence of cholesterol-rich microdomains in the inner leaflet of the plasma membrane.« less

Reassessing ecdysteroidogenic cells from the cell membrane receptors' perspective.

PubMed

Alexandratos, Alexandros; Moulos, Panagiotis; Nellas, Ioannis; Mavridis, Konstantinos; Dedos, Skarlatos G

2016-02-05

Ecdysteroids secreted by the prothoracic gland (PG) cells of insects control the developmental timing of their immature life stages. These cells have been historically considered as carrying out a single function in insects, namely the biochemical conversion of cholesterol to ecdysteroids and their secretion. A growing body of evidence shows that PG cells receive multiple cues during insect development so we tested the hypothesis that they carry out more than just one function in insects. We characterised the molecular nature and developmental profiles of cell membrane receptors in PG cells of Bombyx mori during the final larval stage and determined what receptors decode nutritional, developmental and physiological signals. Through iterative approaches we identified a complex repertoire of cell membrane receptors that are expressed in intricate patterns and activate previously unidentified signal transduction cascades in PG cells. The expression patterns of some of these receptors explain precisely the mechanisms that are known to control ecdysteroidogenesis. However, the presence of receptors for the notch, hedgehog and wingless signalling pathways and the expression of innate immunity-related receptors such as phagocytosis receptors, receptors for microbial ligands and Toll-like receptors call for a re-evaluation of the role these cells play in insects.

DRAM Triggers Lysosomal Membrane Permeabilization and Cell Death in CD4+ T Cells Infected with HIV

PubMed Central

Laforge, Mireille; Limou, Sophie; Harper, Francis; Casartelli, Nicoletta; Rodrigues, Vasco; Silvestre, Ricardo; Haloui, Houda; Zagury, Jean-Francois; Senik, Anna; Estaquier, Jerome

2013-01-01

Productive HIV infection of CD4+ T cells leads to a caspase-independent cell death pathway associated with lysosomal membrane permeabilization (LMP) and cathepsin release, resulting in mitochondrial outer membrane permeabilization (MOMP). Herein, we demonstrate that HIV infection induces damage-regulated autophagy modulator (DRAM) expression in a p53-dependent manner. Knocking down the expression of DRAM and p53 genes with specific siRNAs inhibited autophagy and LMP. However, inhibition of Atg5 and Beclin genes that prevents autophagy had a minor effect on LMP and cell death. The knock down of DRAM gene inhibited cytochrome C release, MOMP and cell death. However, knocking down DRAM, we increased viral infection and production. Our study shows for the first time the involvement of DRAM in host-pathogen interactions, which may represent a mechanism of defense via the elimination of infected cells. PMID:23658518

Effect of Pulsed Electric Field on Membrane Lipids and Oxidative Injury of Salmonella typhimurium

PubMed Central

Yun, Ou; Zeng, Xin-An; Brennan, Charles S.; Han, Zhong

2016-01-01

Salmonella typhimurium cells were subjected to pulsed electric field (PEF) treatment at 25 kV/cm for 0–4 ms to investigate the effect of PEF on the cytoplasmic membrane lipids and oxidative injury of cells. Results indicated that PEF treatment induced a decrease of membrane fluidity of Salmonella typhimurium (S. typhimuriumi), possibly due to the alterations of fatty acid biosynthesis-associated gene expressions (down-regulation of cfa and fabA gene expressions and the up-regulation of fabD gene expression), which, in turn, modified the composition of membrane lipid (decrease in the content ratio of unsaturated fatty acids to saturated fatty acids). In addition, oxidative injury induced by PEF treatment was associated with an increase in the content of malondialdehyde. The up-regulation of cytochrome bo oxidase gene expressions (cyoA, cyoB, and cyoC) indicated that membrane damage was induced by PEF treatment, which was related to the repairing mechanism of alleviating the oxidative injury caused by PEF treatment. Based on these results, we achieved better understanding of microbial injury induced by PEF, suggesting that micro-organisms tend to decrease membrane fluidity in response to PEF treatment and, thus, a greater membrane fluidity might improve the efficiency of PEF treatment to inactivate micro-organisms. PMID:27556460

Expression of interleukin-8 and intercellular cell adhesion molecule-1 in the synovial membrane and cranial cruciate ligament of dogs after rupture of the ligament

PubMed Central

El-Hadi, Mustafa; Charavaryamath, Chandarshekhar; Aebischer, Andrea; Smith, C. Wayne; Shmon, Cindy; Singh, Baljit

2012-01-01

This cross-sectional clinical study compared inflammation, including expression of the chemokine interleukin (IL)-8 and intercellular cell adhesion molecule-1 (ICAM-1), in the stifle joints of 4 control dogs and 23 dogs with cranial cruciate ligament rupture (CCLR). The CCL, synovial membrane, meniscus, cartilage, and synovial fluid from the affected stifle joints of all the dogs were examined. Inflammatory cell counts were performed on the synovial fluid, and the tissues were processed for histologic study and immunohistochemical detection of IL-8 and ICAM-1. The synovial fluid from the stifle joints of the dogs with CCLR had an increased percentage of neutrophils (P = 0.054) and a decreased percentage of lymphocytes (P = 0.004) but not macrophages compared with the fluid from the control dogs. There was accumulation of inflammatory cells and increased expression of IL-8 and ICAM-1 in the vascular endothelium of the synovial membrane and the CCL of the dogs with CCLR. The increase in inflammatory cells in the stifle joints of dogs with CCLR may therefore be due to increased expression of IL-8 and ICAM-1 in the synovial membrane and the CCL after the injury. These data may help in understanding the mechanisms of inflammation associated with CCLR. PMID:22754089

Expression of interleukin-8 and intercellular cell adhesion molecule-1 in the synovial membrane and cranial cruciate ligament of dogs after rupture of the ligament.

PubMed

El-Hadi, Mustafa; Charavaryamath, Chandarshekhar; Aebischer, Andrea; Smith, C Wayne; Shmon, Cindy; Singh, Baljit

2012-01-01

This cross-sectional clinical study compared inflammation, including expression of the chemokine interleukin (IL)-8 and intercellular cell adhesion molecule-1 (ICAM-1), in the stifle joints of 4 control dogs and 23 dogs with cranial cruciate ligament rupture (CCLR). The CCL, synovial membrane, meniscus, cartilage, and synovial fluid from the affected stifle joints of all the dogs were examined. Inflammatory cell counts were performed on the synovial fluid, and the tissues were processed for histologic study and immunohistochemical detection of IL-8 and ICAM-1. The synovial fluid from the stifle joints of the dogs with CCLR had an increased percentage of neutrophils (P = 0.054) and a decreased percentage of lymphocytes (P = 0.004) but not macrophages compared with the fluid from the control dogs. There was accumulation of inflammatory cells and increased expression of IL-8 and ICAM-1 in the vascular endothelium of the synovial membrane and the CCL of the dogs with CCLR. The increase in inflammatory cells in the stifle joints of dogs with CCLR may therefore be due to increased expression of IL-8 and ICAM-1 in the synovial membrane and the CCL after the injury. These data may help in understanding the mechanisms of inflammation associated with CCLR.

Therapeutic potential of Dickkopf-1 in wild-type BRAF papillary thyroid cancer via regulation of β-catenin/E-cadherin signaling.

PubMed

Cho, Sun Wook; Kim, Young A; Sun, Hyun Jin; Ahn, Hwa Young; Lee, Eun Kyung; Yi, Ka Hee; Oh, Byung-Chul; Park, Do Joon; Cho, Bo Youn; Park, Young Joo

2014-09-01

Aberrant activation of the Wnt/β-catenin pathway is a common pathogenesis of various human cancers. We investigated the role of the Wnt inhibitor, Dkk-1, in papillary thyroid cancer (PTC). Immunohistochemical β-catenin staining was performed in tissue microarray containing 148 PTCs and five normal thyroid tissues. In vivo effects of Dkk-1 were explored using ectopic tumors with BHP10-3SC cells. In 27 PTC patients, 60% of patients showed β-catenin up-regulation and Dkk-1 down-regulation in tumor vs normal tissues. Tissue microarray analysis showed that 14 of 148 PTC samples exhibited cytoplasmic-dominant β-catenin expression compared to membranous-dominant expression in normal tissues. Aberrant β-catenin expression was significantly correlated with higher rates of the loss of membranous E-cadherin expression and poor disease-free survival than that in the normal membranous expression group over a median follow-up period of 14 years. Implantation of Dkk-1-overexpressing BHP10-3SC cells revealed delayed tumor growth, resulting from the rescue of membranous β-catenin and E-cadherin expressions. Furthermore, tissue microarray analysis demonstrated that BRAF(WT) patients had higher rates of aberrant expressions of β-catenin and E-cadherin than BRAF(V600E) patients. Indeed, the inhibitory effects of Dkk-1 on cell survival were more sensitive in BRAF(WT) (BHP10-3SC and TPC-1) than in BRAF(V600E) (SNU-790 and BCPAP) cells. Overexpression of BRAF(V600E) in normal thyroid epithelial (H tori) cells also reduced the effects of Dkk-1 on cell survival. A subset of PTC patients showed aberrant expression of β-catenin/E-cadherin signaling and poor disease-free survival. Dkk-1 might have a therapeutic role, particularly in BRAF(WT) patients.

Engineering artificial cells by combining HeLa-based cell-free expression and ultra-thin double emulsion template

PubMed Central

Ho, Kwun Yin; Murray, Victoria L.; Liu, Allen P.

2015-01-01

Generation of artificial cells provides the bridge needed to cover the gap between studying the complexity of biological processes in whole cells and studying these same processes in an in vitro reconstituted system. Artificial cells are defined as the encapsulation of biologically active material in a biological or synthetic membrane. Here, we describe a robust and general method to produce artificial cells for the purpose of mimicking one or more behaviors of a cell. A microfluidic double emulsion system is used to encapsulate a mammalian cell free expression system that is able to express membrane proteins into the bilayer or soluble proteins inside the vesicles. The development of a robust platform that allows the assembly of artificial cells is valuable in understanding subcellular functions and emergent behaviors in a more cell-like environment as well as for creating novel signaling pathways to achieve specific cellular behaviors. PMID:25997354

Characterization, cell-surface expression and ligand-binding properties of different truncated N-terminal extracellular domains of the ionotropic glutamate receptor subunit GluR1.

PubMed

McIlhinney, R A; Molnár, E

1996-04-01

To identify the location of the first transmembrane segment of the GluR1 glutamate receptor subunit artificial stop codons have been introduced into the N-terminal domain at amino acid positions 442, 510, and 563, namely just before and spanning the proposed first two transmembrane regions. The resultant truncated N-terminal fragments of GluR1, termed NT1, NT2, and NT3 respectively were expressed in Cos-7 cells and their cellular distribution and cell-surface expression analysed using an N-terminal antibody to GluR1. All of the fragments were fully glycosylated and were found to be associated with cell membranes but none was secreted. Differential extraction of the cell membranes indicated that both NT1 and NT2 behave as peripheral membrane proteins. In contrast NT3, like the full subunit, has integral membrane protein properties. Furthermore only NT3 is expressed at the cell surface as determined by immunofluorescence and cell-surface biotinylation. Protease protection assays indicated that only NT3 had a cytoplasmic tail. Binding studies using the selective ligand [(3)H]alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate ([(3)H]AMPA) demonstrated that NT3 does not bind ligand. Together these results indicate that the first transmembrane domain of the GluR1 subunit lies between residues 509 and 562, that the N-terminal domain alone cannot form a functional ligand-binding site and that this domain can be targeted to the cell surface provided that it has a transmembrane-spanning region.

Coupling neutron reflectivity with cell-free protein synthesis to probe membrane protein structure in supported bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soranzo, Thomas; Martin, Donald K.; Lenormand, Jean -Luc

Here, the structure of the p7 viroporin, an oligomeric membrane protein ion channel involved in the assembly and release of the hepatitis C virus, was determined from proteins expressed and inserted directly into supported model lipid membranes using cell-free protein expression. Cell-free protein expression allowed (i) high protein concentration in the membrane, (ii) control of the protein’s isotopic constitution, and (iii) control over the lipid environment available to the protein. Here, we used cell-free protein synthesis to directly incorporate the hepatitis C virus (HCV) p7 protein into supported lipid bilayers formed from physiologically relevant lipids (POPC or asolectin) for bothmore » direct structural measurements using neutron reflectivity (NR) and conductance measurements using electrical impedance spectroscopy (EIS). We report that HCV p7 from genotype 1a strain H77 adopts a conical shape within lipid bilayers and forms a viroporin upon oligomerization, confirmed by EIS conductance measurements. This combination of techniques represents a novel approach to the study of membrane proteins and, through the use of selective deuteration of particular amino acids to enhance neutron scattering contrast, has the promise to become a powerful tool for characterizing the protein conformation in physiologically relevant environments and for the development of biosensor applications.« less

Coupling neutron reflectivity with cell-free protein synthesis to probe membrane protein structure in supported bilayers

DOE PAGES

Soranzo, Thomas; Martin, Donald K.; Lenormand, Jean -Luc; ...

2017-06-13

Here, the structure of the p7 viroporin, an oligomeric membrane protein ion channel involved in the assembly and release of the hepatitis C virus, was determined from proteins expressed and inserted directly into supported model lipid membranes using cell-free protein expression. Cell-free protein expression allowed (i) high protein concentration in the membrane, (ii) control of the protein’s isotopic constitution, and (iii) control over the lipid environment available to the protein. Here, we used cell-free protein synthesis to directly incorporate the hepatitis C virus (HCV) p7 protein into supported lipid bilayers formed from physiologically relevant lipids (POPC or asolectin) for bothmore » direct structural measurements using neutron reflectivity (NR) and conductance measurements using electrical impedance spectroscopy (EIS). We report that HCV p7 from genotype 1a strain H77 adopts a conical shape within lipid bilayers and forms a viroporin upon oligomerization, confirmed by EIS conductance measurements. This combination of techniques represents a novel approach to the study of membrane proteins and, through the use of selective deuteration of particular amino acids to enhance neutron scattering contrast, has the promise to become a powerful tool for characterizing the protein conformation in physiologically relevant environments and for the development of biosensor applications.« less

Regulation of cellular function via electromagnetic field frequency and extracellular environment: A theoretical- experimental approach

NASA Astrophysics Data System (ADS)

Taghian, Toloo; Sheikh, Abdul; Narmoneva, Daria; Kogan, Andrei

2015-03-01

Application of external electric field (EF) as a non-pharmacological, non-invasive tool to control cell function is of great therapeutic interest. We developed a theoretical-experimental approach to investigate the biophysical mechanisms of EF interaction with cells in electrode-free physiologically-relevant configuration. Our numerical results demonstrated that EF frequency is the major parameter to control cell response to EF. Non-oscillating or low-frequency EF leads to charge accumulation on the cell surface membrane that may mediate membrane initiated cell responses. In contrast, high-frequency EF penetrates the cell membrane and reaches cell cytoplasm, where it may directly activate intracellular responses. The theoretical predictions were confirmed in our experimental studies of the effects of applied EF on vascular cell function. Results show that non-oscillating EF increases vascular endothelial growth factor (VEGF) expression while field polarity controls cell adhesion rate. High-frequency, but not low frequency, EF provides differential regulation of cytoplasmic focal adhesion kinase and VEGF expression depending on the substrate, with increased expression in cells cultured on RGD-rich synthetic hydrogels, and decreased expression for matrigel culture. The authors acknowledge the financial support from the NSF (DMR-1206784 & DMR-0804199 to AK); the NIH (1R21 DK078814-01A1 to DN) and the University of Cincinnati (Interdisciplinary Faculty Research Support Grant to DN and AK).

Electrospun nanofibrous SF/P(LLA-CL) membrane: a potential substratum for endothelial keratoplasty.

PubMed

Chen, Junzhao; Yan, Chenxi; Zhu, Mengyu; Yao, Qinke; Shao, Chunyi; Lu, Wenjuan; Wang, Jing; Mo, Xiumei; Gu, Ping; Fu, Yao; Fan, Xianqun

2015-01-01

Cornea transplant technology has progressed markedly in recent decades, allowing surgeons to replace diseased corneal endothelium by a thin lamellar structure. A thin, transparent, biocompatible, tissue-engineered substratum with corneal endothelial cells for endothelial keratoplasty is currently of interest. Electrospinning a nanofibrous structure can simulate the extracellular matrix and have beneficial effects for cell culture. Silk fibroin (SF) has good biocompatibility but poor mechanical properties, while poly(L-lactic acid-co-ε-caprolactone) (P(LLA-CL)) has good mechanical properties but poor biocompatibility. Blending SF with P(LLA-CL) can maintain the advantages of both these materials and overcome their disadvantages. Blended electrospun nanofibrous membranes may be suitable for regeneration of the corneal endothelium. The aim of this study was to produce a tissue-engineered construct suitable for endothelial keratoplasty. Five scaffolds containing different SF:P(LLA-CL) blended ratios (100:0, 75:25, 50:50, 25:75, 0:100) were manufactured. A human corneal endothelial (B4G12) cell line was cultured on the membranes. Light transmission, speed of cell adherence, cell viability (live-dead test), cell proliferation (Ki-67, BrdU staining), and cell monolayer formation were detected on membranes with the different blended ratios, and expression of some functional genes was also detected by real-time polymerase chain reaction. Different blended ratios of scaffolds had different light transmittance properties. The 25:75 blended ratio membrane had the best transmittance among these scaffolds. All electrospun nanofibrous membranes showed improved speed of cell adherence when compared with the control group, especially when the P(LLA-CL) ratio increased. The 25:75 blended ratio membranes also had the highest cell proliferation. B4G12 cells could form a monolayer on all scaffolds, and most functional genes were also stably expressed on all scaffolds. Only two genes showed changes in expression. All blended ratios of SF:P(LLA-CL) scaffolds were evaluated and showed good biocompatibility for cell adherence and monolayer formation. Among them, the 25:75 blended ratio SF:P(LLA-CL) scaffold had the best transmittance and the highest cell proliferation. These attributes further the potential application of the SF:P(LLA-CL) scaffold for corneal endothelial transplantation.

Expression and Association of the Yersinia pestis Translocon Proteins, YopB and YopD, Are Facilitated by Nanolipoprotein Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coleman, Matthew A.; Cappuccio, Jenny A.; Blanchette, Craig D.

Yersinia pestis enters host cells and evades host defenses, in part, through interactions between Yersinia pestis proteins and host membranes. One such interaction is through the type III secretion system, which uses a highly conserved and ordered complex for Yersinia pestis outer membrane effector protein translocation called the injectisome. The portion of the injectisome that interacts directly with host cell membranes is referred to as the translocon. The translocon is believed to form a pore allowing effector molecules to enter host cells. To facilitate mechanistic studies of the translocon, we have developed a cell-free approach for expressing translocon pore proteinsmore » as a complex supported in a bilayer membrane mimetic nano-scaffold known as a nanolipoprotein particle (NLP) Initial results show cell-free expression of Yersinia pestis outer membrane proteins YopB and YopD was enhanced in the presence of liposomes. However, these complexes tended to aggregate and precipitate. With the addition of co-expressed (NLP) forming components, the YopB and/or YopD complex was rendered soluble, increasing the yield of protein for biophysical studies. Biophysical methods such as Atomic Force Microscopy and Fluorescence Correlation Spectroscopy were used to confirm that the soluble YopB/D complex was associated with NLPs. An interaction between the YopB/D complex and NLP was validated by immunoprecipitation. The YopB/D translocon complex embedded in a NLP provides a platform for protein interaction studies between pathogen and host proteins. Ultimately, these studies will help elucidate the poorly understood mechanism which enables this pathogen to inject effector proteins into host cells, thus evading host defenses.« less

Expression and Association of the Yersinia pestis Translocon Proteins, YopB and YopD, Are Facilitated by Nanolipoprotein Particles

DOE PAGES

Coleman, Matthew A.; Cappuccio, Jenny A.; Blanchette, Craig D.; ...

2016-03-25

Yersinia pestis enters host cells and evades host defenses, in part, through interactions between Yersinia pestis proteins and host membranes. One such interaction is through the type III secretion system, which uses a highly conserved and ordered complex for Yersinia pestis outer membrane effector protein translocation called the injectisome. The portion of the injectisome that interacts directly with host cell membranes is referred to as the translocon. The translocon is believed to form a pore allowing effector molecules to enter host cells. To facilitate mechanistic studies of the translocon, we have developed a cell-free approach for expressing translocon pore proteinsmore » as a complex supported in a bilayer membrane mimetic nano-scaffold known as a nanolipoprotein particle (NLP) Initial results show cell-free expression of Yersinia pestis outer membrane proteins YopB and YopD was enhanced in the presence of liposomes. However, these complexes tended to aggregate and precipitate. With the addition of co-expressed (NLP) forming components, the YopB and/or YopD complex was rendered soluble, increasing the yield of protein for biophysical studies. Biophysical methods such as Atomic Force Microscopy and Fluorescence Correlation Spectroscopy were used to confirm that the soluble YopB/D complex was associated with NLPs. An interaction between the YopB/D complex and NLP was validated by immunoprecipitation. The YopB/D translocon complex embedded in a NLP provides a platform for protein interaction studies between pathogen and host proteins. Ultimately, these studies will help elucidate the poorly understood mechanism which enables this pathogen to inject effector proteins into host cells, thus evading host defenses.« less

Vesicle-associated membrane protein 2 mediates trafficking of {alpha}5{beta}1 integrin to the plasma membrane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasan, Nazarul; Hu, Chuan, E-mail: chuan.hu@louisville.edu

2010-01-01

Integrins are major receptors for cell adhesion to the extracellular matrix (ECM). As transmembrane proteins, the levels of integrins at the plasma membrane or the cell surface are ultimately determined by the balance between two vesicle trafficking events: endocytosis of integrins at the plasma membrane and exocytosis of the vesicles that transport integrins. Here, we report that vesicle-associated membrane protein 2 (VAMP2), a SNARE protein that mediates vesicle fusion with the plasma membrane, is involved in the trafficking of {alpha}5{beta}1 integrin. VAMP2 was present on vesicles containing endocytosed {beta}1 integrin. Small interfering RNA (siRNA) silencing of VAMP2 markedly reduced cellmore » surface {alpha}5{beta}1 and inhibited cell adhesion and chemotactic migration to fibronectin, the ECM ligand of {alpha}5{beta}1, without altering cell surface expression of {alpha}2{beta}1 integrin or {alpha}3{beta}1 integrin. By contrast, silencing of VAMP8, another SNARE protein, had no effect on cell surface expression of the integrins or cell adhesion to fibronectin. In addition, VAMP2-mediated trafficking is involved in cell adhesion to collagen but not to laminin. Consistent with disruption of integrin functions in cell proliferation and survival, VAMP2 silencing diminished proliferation and triggered apoptosis. Collectively, these data indicate that VAMP2 mediates the trafficking of {alpha}5{beta}1 integrin to the plasma membrane and VAMP2-dependent integrin trafficking is critical in cell adhesion, migration and survival.« less

Hyper-expression of PAX2 in human metastatic prostate tumors and its role as a cancer promoter in an in vitro invasion model.

PubMed

Ueda, Takashi; Ito, Saya; Shiraishi, Takumi; Kulkarni, Prakash; Ueno, Akihisa; Nakagawa, Hideo; Kimura, Yasunori; Hongo, Fumiya; Kamoi, Kazumi; Kawauchi, Akihiro; Miki, Tsuneharu

2013-09-01

Metastasis is a consequence of many biological events, during which cancer stem cells are shifted into a malignant state. Among these events, invasion of prostate cancer cells into host tissues is possible to be assessed by means of an in vitro invasion model, and is thought to be coupled to altered expression of membrane proteins. Dysregulated functions of the factors regulating organogenesis during embryogenesis are known to facilitate metastasis of many types of cancers. PAX2 (paired box 2) is a member of the PAX transcription factor family, which regulates prostatic ductal growth and branching in organogenesis of mammalian prostates. However, the role of PAX2 in prostate cancer development remains to be determined. PAX2 expression in human prostate cancers and normal prostate epithelium were examined by quantitative RT-PCR and immunohistochemistry. Matrigel invasion assay and a gene array analysis were performed using prostate cancer cell lines transfected with either control or PAX2 siRNA. In human prostate cancers, PAX2 was hyper-expressed in metastatic cancers, but was expressed at lower levels in non-metastatic cancers. Consistent with this, PAX2 knockdown repressed cell growth and invasion in a Matrigel invasion assay. Gene ontology analysis revealed that many cell membrane proteins were downregulated after PAX2 knockdown. Our data suggested that PAX2 hyper-expression promotes the development of the metastatic state in prostate cancer cells, presumably through upregulating the expression of cell membrane proteins. Copyright © 2013 Wiley Periodicals, Inc.

Fluorescence spectroscopy studies of HEK293 cells expressing DOR-Gi1α fusion protein; the effect of cholesterol depletion.

PubMed

Brejchová, Jana; Sýkora, Jan; Dlouhá, Kateřina; Roubalová, Lenka; Ostašov, Pavel; Vošahlíková, Miroslava; Hof, Martin; Svoboda, Petr

2011-12-01

Biophysical studies of fluorescence anisotropy of DPH and Laurdan generalized polarization were performed in plasma membranes (PM) isolated from control and cholesterol-depleted HEK293 cells stably expressing pertussis toxin (PTX)-insensitive DOR-Gi1α (Cys351-Ile351) fusion protein. PM isolated from control, PTX-untreated, cells were compared with PM isolated from PTX-treated cells. Results from both types of PM indicated that i) hydrophobic membrane interior was made more accessible to water molecules and more chaotically organized in cholesterol-depleted samples, ii) cholesterol depletion resulted in an overall increase in surface area of membrane, membrane fluidity, and mobility of its constituents. Analysis of DOR-Gi1α coupling in PTX-treated and PTX-untreated cells indicated that cholesterol depletion did not alter the agonist binding site of DOR (Bmax and Kd) but the ability of DOR agonist DADLE to activate G proteins was markedly impaired. In PTX-untreated membranes, EC50 for DADLE-stimulated [35S]GTPγS binding was shifted by one order of magnitude to the right: from 4.3±1.2×10(-9) M to 2.2±1.3×10(-8) M in control and cholesterol-depleted membrane samples, respectively. In PTX-treated membranes, EC50 was shifted from 4.5±1.1×10(-9) M to 2.8±1.4×10(-8) M. In summary, the perturbation of optimum PM organization by cholesterol depletion deteriorates functional coupling of DOR to covalently bound Gi1α as well as endogenously expressed PTX-sensitive G proteins of Gi/Go family while receptor ligand binding site is unchanged. The biophysical state of hydrophobic plasma (cell) membrane interior should be regarded as regulatory factor of DOR-signaling cascade. Copyright © 2011 Elsevier B.V. All rights reserved.

Epstein-Barr virus latent membrane protein expression in Hodgkin and Reed-Sternberg cells.

PubMed Central

Herbst, H; Dallenbach, F; Hummel, M; Niedobitek, G; Pileri, S; Müller-Lantzsch, N; Stein, H

1991-01-01

Cryostat sections from lymph nodes of 47 Hodgkin disease patients were examined by immunohistology for the Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP), nuclear antigen 2, and late viral glycoprotein gp350/250. A distinct LMP-specific membrane and cytoplasmic staining was detected exclusively in Hodgkin and Reed-Sternberg cells in 18 patients (38%); EBV nuclear antigen 2 and gp350/250 immunoreactivity was absent in all instances. Thirty-two of 47 (68%) cases contained EBV-specific DNA sequences as detected by PCR, all LMP-positive cases being in this category. Our results confirm previous studies establishing the presence of EBV genomes in Hodgkin and Reed-Sternberg cells by demonstrating expression of an EBV-encoded protein in the tumor-cell population. The finding of LMP expression in the absence of EBV nuclear antigen 2 suggests a pattern of EBV gene expression different from that of B-lymphoblastoid cell lines and Burkitt lymphoma, whereas this finding shows similarities with that seen in undifferentiated nasopharyngeal carcinoma. Because the LMP gene has transforming potential, our findings support the concept of a pathoetiological role of EBV in many cases of Hodgkin disease. Images PMID:1647016

Expression analysis of two gene subfamilies encoding the plasma membrane H+-ATPase in Nicotiana plumbaginifolia reveals the major transport functions of this enzyme.

PubMed

Moriau, L; Michelet, B; Bogaerts, P; Lambert, L; Michel, A; Oufattole, M; Boutry, M

1999-07-01

The plasma membrane H+-ATPase couples ATP hydrolysis to proton transport, thereby establishing the driving force for solute transport across the plasma membrane. In Nicotiana plumbaginifolia, this enzyme is encoded by at least nine pma (plasma membrane H+-ATPase) genes. Four of these are classified into two gene subfamilies, pma1-2-3 and pma4, which are the most highly expressed in plant species. We have isolated genomic clones for pma2 and pma4. Mapping of their transcript 5' end revealed the presence of a long leader that contained small open reading frames, regulatory features typical of other pma genes. The gusA reporter gene was then used to determine the expression of pma2, pma3 and pma4 in N. tabacum. These data, together with those obtained previously for pma1, led to the following conclusions. (i) The four pma-gusA genes were all expressed in root, stem, leaf and flower organs, but each in a cell-type specific manner. Expression in these organs was confirmed at the protein level, using subfamily-specific antibodies. (ii) pma4-gusA was expressed in many cell types and notably in root hair and epidermis, in companion cells, and in guard cells, indicating that in N. plumbaginifolia the same H+-ATPase isoform might be involved in mineral nutrition, phloem loading and control of stomata aperture. (iii) The second gene subfamily is composed, in N. plumbaginifolia, of a single gene (pma4) with a wide expression pattern and, in Arabidopsis thaliana, of three genes (aha1, aha2, aha3), at least two of them having a more restrictive expression pattern. (iv) Some cell types expressed pma2 and pma4 at the same time, which encode H+-ATPases with different enzymatic properties.

Modulation of epithelial sodium channel trafficking and function by sodium 4-phenylbutyrate in human nasal epithelial cells.

PubMed

Prulière-Escabasse, Virginie; Planès, Carole; Escudier, Estelle; Fanen, Pascale; Coste, André; Clerici, Christine

2007-11-23

Sodium 4-phenylbutyrate (4-PBA) has been shown to correct the cellular trafficking of several mutant or nonmutant plasma membrane proteins such as cystic fibrosis transmembrane conductance regulator through the expression of 70-kDa heat shock proteins. The objective of the study was to determine whether 4-PBA may influence the functional expression of epithelial sodium channels (ENaC) in human nasal epithelial cells (HNEC). Using primary cultures of HNEC, we demonstrate that 4-PBA (5 mm for 6 h) markedly stimulated amiloride-sensitive sodium channel activity and that this was related to an increased abundance of alpha-, beta-, and gamma-ENaC subunits in the apical membrane. The increase in ENaC cell surface expression (i) was due to insertion of newly ENaC subunits as determined by brefeldin A experiments and (ii) was not associated with cell surface retention of ENaC subunits because endocytosis of ENaC subunits was unchanged. In addition, we find that ENaC co-immunoprecipitated with the heat shock protein constitutively expressed Hsc70, that has been reported to modulate ENaC trafficking, and that 4-PBA decreased Hsc70 protein level. Finally, we report that in cystic fibrosis HNEC obtained from two cystic fibrosis patients, 4-PBA increased functional expression of ENaC as demonstrated by the increase in amiloride-sensitive sodium transport and in alpha-, beta-, and gamma-ENaC subunit expression in the apical membrane. Our results suggest that in HNEC, 4-PBA increases the functional expression of ENaC through the insertion of new alpha-, beta-, and gamma-ENaC subunits into the apical membrane and also suggest that 4-PBA could modify ENaC trafficking by reducing Hsc70 protein expression.

Membrane microdomains in immunity: glycosphingolipid-enriched domain-mediated innate immune responses.

PubMed

Iwabuchi, Kazuhisa; Nakayama, Hitoshi; Masuda, Hiromi; Kina, Katsunari; Ogawa, Hideoki; Takamori, Kenji

2012-01-01

Over the last 30 years, many studies have indicated that glycosphingolipids (GSLs) expressed on the cell surface may act as binding sites for microorganisms. Based on their physicochemical characteristics, GSLs form membrane microdomains with cholesterol, sphingomyelin, glycosylphosphatidylinositol (GPI)-anchored proteins, and various signaling molecules, and GSL-enriched domains have been shown to be involved in these defense responses. Among the GSLs, lactosylceramide (LacCer, CDw17) can bind to various microorganisms. LacCer is expressed at high levels on the plasma membrane of human neutrophils, and forms membrane microdomains associated with the Src family tyrosine kinase Lyn. LacCer-enriched membrane microdomains mediate superoxide generation, chemotaxis, and non-opsonic phagocytosis. Therefore, LacCer-enriched membrane microdomains are thought to function as pattern recognition receptors (PRRs) to recognize pathogen-associated molecular patterns (PAMPs) expressed on microorganisms. In contrast, several pathogens have developed infection mechanisms using membrane microdomains. In addition, some pathogens have the ability to avoid degradation by escaping from the vacuolar compartment or preventing phagosome maturation, utilizing membrane microdomains, such as LacCer-enriched domains, of host cells. The detailed molecular mechanisms of these membrane microdomain-associated host-pathogen interactions remain to be elucidated. Copyright © 2012 International Union of Biochemistry and Molecular Biology, Inc.

NHS-A isoform of the NHS gene is a novel interactor of ZO-1.

PubMed

Sharma, Shiwani; Koh, Katrina S Y; Collin, Caitlin; Dave, Alpana; McMellon, Amy; Sugiyama, Yuki; McAvoy, John W; Voss, Anne K; Gécz, Jozef; Craig, Jamie E

2009-08-15

Mutations in the NHS (Nance-Horan Syndrome) gene lead to severe congenital cataracts, dental defects and sometimes mental retardation. NHS encodes two protein isoforms, NHS-A and -1A that display cell-type dependent differential expression and localization. Here we demonstrate that of these two isoforms, the NHS-A isoform associates with the cell membrane in the presence of intercellular contacts and it immunoprecipitates with the tight junction protein ZO-1 in MDCK (Madin Darby Canine Kidney) epithelial cells and in neonatal rat lens. The NHS-1A isoform however is a cytoplasmic protein. Both Nhs isoforms are expressed during mouse development. Immunolabelling of developing mouse with the anti-NHS antibody that detects both isoforms revealed the protein in the developing head including the eye and brain. It was primarily expressed in epithelium including neural epithelium and certain vascular endothelium but only weakly expressed in mesenchymal cells. In the epithelium and vascular endothelium the protein associated with the cell membrane and co-localized with ZO-1, which indirectly indicates expression of the Nhs-A isoform in these structures. Membrane localization of the protein in the lens vesicle similarly supports Nhs-A expression. In conclusion, the NHS-A isoform of NHS is a novel interactor of ZO-1 and may have a role at tight junctions. This isoform is important in mammalian development especially of the organs in the head.

Suppression of c-Myc is involved in multi-walled carbon nanotubes' down-regulation of ATP-binding cassette transporters in human colon adenocarcinoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhaojing; Xu, Yonghong; Meng, Xiangning

Over-expression of ATP-binding cassette (ABC) transporters, a large family of integral membrane proteins that decrease cellular drug uptake and accumulation by active extrusion, is one of the major causes of cancer multi-drug resistance (MDR) that frequently leads to failure of chemotherapy. Carbon nanotubes (CNTs)-based drug delivery devices hold great promise in enhancing the efficacy of cancer chemotherapy. However, CNTs' effects on the ABC transporters remain under-investigated. In this study, we found that multiwalled carbon nanotubes (MWCNTs) reduced transport activity and expression of ABC transporters including ABCB1/Pgp and ABCC4/MRP4 in human colon adenocarcinoma Caco-2 cells. Proto-oncogene c-Myc, which directly regulates ABCmore » gene expression, was concurrently decreased in MWCNT-treated cells and forced over-expression of c-Myc reversed MWCNTs' inhibitory effects on ABCB1 and ABCC4 expression. MWCNT-cell membrane interaction and cell membrane oxidative damage were observed. However, antioxidants such as vitamin C, β-mecaptoethanol and dimethylthiourea failed to antagonize MWCNTs' down-regulation of ABC transporters. These data suggest that MWCNTs may act on c-Myc, but not through oxidative stress, to down-regulate ABC transporter expression. Our findings thus shed light on CNTs' novel cellular effects that may be utilized to develop CNTs-based drug delivery devices to overcome ABC transporter-mediated cancer chemoresistance.« less

GSL-enriched membrane microdomains in innate immune responses.

PubMed

Nakayama, Hitoshi; Ogawa, Hideoki; Takamori, Kenji; Iwabuchi, Kazuhisa

2013-06-01

Many pathogens target glycosphingolipids (GSLs), which, together with cholesterol, GPI-anchored proteins, and various signaling molecules, cluster on host cell membranes to form GSL-enriched membrane microdomains (lipid rafts). These GSL-enriched membrane microdomains may therefore be involved in host-pathogen interactions. Innate immune responses are triggered by the association of pathogens with phagocytes, such as neutrophils, macrophages and dendritic cells. Phagocytes express a diverse array of pattern-recognition receptors (PRRs), which sense invading microorganisms and trigger pathogen-specific signaling. PRRs can recognize highly conserved pathogen-associated molecular patterns expressed on microorganisms. The GSL lactosylceramide (LacCer, CDw17), which binds to various microorganisms, including Candida albicans, is expressed predominantly on the plasma membranes of human mature neutrophils and forms membrane microdomains together with the Src family tyrosine kinase Lyn. These LacCer-enriched membrane microdomains can mediate superoxide generation, migration, and phagocytosis, indicating that LacCer functions as a PRR in innate immunity. Moreover, the interactions of GSL-enriched membrane microdomains with membrane proteins, such as growth factor receptors, are important in mediating the physiological properties of these proteins. Similarly, we recently found that interactions between LacCer-enriched membrane microdomains and CD11b/CD18 (Mac-1, CR3, or αMβ2-integrin) are significant for neutrophil phagocytosis of non-opsonized microorganisms. This review describes the functional role of LacCer-enriched membrane microdomains and their interactions with CD11b/CD18.

Membrane Protein Mobility and Orientation Preserved in Supported Bilayers Created Directly from Cell Plasma Membrane Blebs.

PubMed

Richards, Mark J; Hsia, Chih-Yun; Singh, Rohit R; Haider, Huma; Kumpf, Julia; Kawate, Toshimitsu; Daniel, Susan

2016-03-29

Membrane protein interactions with lipids are crucial for their native biological behavior, yet traditional characterization methods are often carried out on purified protein in the absence of lipids. We present a simple method to transfer membrane proteins expressed in mammalian cells to an assay-friendly, cushioned, supported lipid bilayer platform using cell blebs as an intermediate. Cell blebs, expressing either GPI-linked yellow fluorescent proteins or neon-green fused transmembrane P2X2 receptors, were induced to rupture on glass surfaces using PEGylated lipid vesicles, which resulted in planar supported membranes with over 50% mobility for multipass transmembrane proteins and over 90% for GPI-linked proteins. Fluorescent proteins were tracked, and their diffusion in supported bilayers characterized, using single molecule tracking and moment scaling spectrum (MSS) analysis. Diffusion was characterized for individual proteins as either free or confined, revealing details of the local lipid membrane heterogeneity surrounding the protein. A particularly useful result of our bilayer formation process is the protein orientation in the supported planar bilayer. For both the GPI-linked and transmembrane proteins used here, an enzymatic assay revealed that protein orientation in the planar bilayer results in the extracellular domains facing toward the bulk, and that the dominant mode of bleb rupture is via the "parachute" mechanism. Mobility, orientation, and preservation of the native lipid environment of the proteins using cell blebs offers advantages over proteoliposome reconstitution or disrupted cell membrane preparations, which necessarily result in significant scrambling of protein orientation and typically immobilized membrane proteins in SLBs. The bleb-based bilayer platform presented here is an important step toward integrating membrane proteomic studies on chip, especially for future studies aimed at understanding fundamental effects of lipid interactions on protein activity and the roles of membrane proteins in disease pathways.

Induction of functional Fc receptors in P388 leukemia cells. Requirement for multiple differentiation signals.

PubMed

Cohen, D A; Stotelmyer, N L; Kaplan, A M

1985-04-01

The development of functional Fc receptors (FcR) during induced differentiation with the tumor promoter, phorbol myristate acetate (PMA), was studied in the murine tumor cell line, P388. PMA induced the appearance of FcR on the membranes of P388 cells as indicated by the binding of IgG-coated sheep red blood cells (IgG-SRBC). Concentrations of PMA as low as 1 ng/ml were sufficient to induce the expression of FcR as well as to inhibit cellular division and to induce adherence in the P388 tumor cell line; however, optimal FcR induction occurred at PMA concentrations of 10-100 ng/ml. Immunofluorescent analysis with heat-aggregated myeloma proteins indicated that PMA induced FcR which were capable of binding IgG2a and IgG2b immunoglobulins, but not IgG1. Adherence to a substratum was determined to be a second required signal for expression of FcR, since PMA induction of P388 tumor cells in teflon dishes failed to fully develop FcR and adherence of P388 cells to poly-L-lysine-coated culture dishes in the absence of PMA was insufficient for FcR expression. FcR which appeared after PMA induction were non-functional in the sense that membrane-bound IgG-SRBC were not ingested to any significant extent by the tumor cells. However, if FcR induction occurred in the presence conA-induced rat spleen cell culture supernatants, phagocytosis of membrane-bound erythrocytes occurred. These findings suggest that for the expression of FcR which are capable of particle internalization, at least three identifiable membrane-transmitted signals are required during differentiation.

Sch proteins are localized on endoplasmic reticulum membranes and are redistributed after tyrosine kinase receptor activation.

PubMed Central

Lotti, L V; Lanfrancone, L; Migliaccio, E; Zompetta, C; Pelicci, G; Salcini, A E; Falini, B; Pelicci, P G; Torrisi, M R

1996-01-01

The intracellular localization of Shc proteins was analyzed by immunofluorescence and immunoelectron microscopy in normal cells and cells expressing the epidermal growth factor receptor or the EGFR/erbB2 chimera. In unstimulated cells, the immunolabeling was localized in the central perinuclear area of the cell and mostly associated with the cytosolic side of rough endoplasmic reticulum membranes. Upon epidermal growth factor treatment and receptor tyrosine kinase activation, the immunolabeling became peripheral and was found to be associated with the cytosolic surface of the plasma membrane and endocytic structures, such as coated pits and endosomes, and with the peripheral cytosol. Receptor activation in cells expressing phosphorylation-defective mutants of Shc and erbB-2 kinase showed that receptor autophosphorylation, but not Shc phosphorylation, is required for redistribution of Shc proteins. The rough endoplasmic reticulum localization of Shc proteins in unstimulated cells and their massive recruitment to the plasma membrane, endocytic structures, and peripheral cytosol following receptor tyrosine kinase activation could account for multiple putative functions of the adaptor protein. PMID:8628261

Small-angle X-ray and neutron scattering demonstrates that cell-free expression produces properly formed disc-shaped nanolipoprotein particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cleveland, Thomas E.; He, Wei; Evans, Angela C.

Nanolipoprotein particles (NLPs), composed of membrane scaffold proteins and lipids, have been used to support membrane proteins in a native-like bilayer environment for biochemical and structural studies. Traditionally, these NLPs have been prepared by the controlled removal of detergent from a detergent-solubilized protein-lipid mixture. Recently, an alternative method has been developed using direct cell-free expression of the membrane scaffold protein in the presence of preformed lipid vesicles, which spontaneously produces NLPs without the need for detergent at any stage. Using SANS/SAXS, we show here that NLPs produced by this cell-free expression method are structurally indistinguishable from those produced using detergentmore » removal methodologies. This further supports the utility of single step cell-free methods for the production of lipid binding proteins. Lastly, in addition, detailed structural information describing these NLPs can be obtained by fitting a capped core-shell cylinder type model to all SANS/SAXS data simultaneously.« less

Small-angle X-ray and neutron scattering demonstrates that cell-free expression produces properly formed disc-shaped nanolipoprotein particles

DOE PAGES

Cleveland, Thomas E.; He, Wei; Evans, Angela C.; ...

2018-02-13

Nanolipoprotein particles (NLPs), composed of membrane scaffold proteins and lipids, have been used to support membrane proteins in a native-like bilayer environment for biochemical and structural studies. Traditionally, these NLPs have been prepared by the controlled removal of detergent from a detergent-solubilized protein-lipid mixture. Recently, an alternative method has been developed using direct cell-free expression of the membrane scaffold protein in the presence of preformed lipid vesicles, which spontaneously produces NLPs without the need for detergent at any stage. Using SANS/SAXS, we show here that NLPs produced by this cell-free expression method are structurally indistinguishable from those produced using detergentmore » removal methodologies. This further supports the utility of single step cell-free methods for the production of lipid binding proteins. Lastly, in addition, detailed structural information describing these NLPs can be obtained by fitting a capped core-shell cylinder type model to all SANS/SAXS data simultaneously.« less

Opposing effects of estradiol- and testosterone-membrane binding sites on T47D breast cancer cell apoptosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kampa, Marilena; Nifli, Artemissia-Phoebe; Charalampopoulos, Ioannis

Classical steroid mode of action involves binding to intracellular receptors, the later acting as ligand-activated nuclear transcription factors. Recently, membrane sites for different steroids have been also identified, mediating rapid, non-genomic, steroid actions. Membrane sites for estrogen and androgen have been found in a number of different cell types, bearing or not classical intracellular receptors. In the present study, with the use of radioligand binding, flow cytometry and confocal laser microscopy, we report that T47D human breast cancer cells express specific and saturable membrane receptors for both estrogen (K {sub D} 4.06 {+-} 3.31 nM) and androgen (K {sub D}more » 7.64 {+-} 3.15 nM). Upon activation with BSA-conjugated, non-permeable ligands (E{sub 2}-BSA and testosterone-BSA), membrane estrogen receptors protect cells from serum-deprivation-induced apoptosis, while androgen receptors induce apoptosis in serum-supplemented T47D cells. In addition, co-incubation of cells with a fixed concentration of one steroid and varying concentrations of the other reversed the abovementioned effect (apoptosis for androgen, and anti-apoptosis for E{sub 2}), suggesting that the fate of the cell depends on the relative concentration of either steroid in the culture medium. We also report the identification of membrane receptors for E{sub 2} and androgen in biopsy slides from breast cancer patients. Both sites are expressed, with the staining for membrane E{sub 2} being strongly present in ER-negative, less differentiated, more aggressive tumors. These findings suggest that aromatase inhibitors may exert their beneficial effects on breast cancer by also propagating the metabolism of local steroids towards androgen, inducing thus cell apoptosis through membrane androgen receptor activation.« less

Endothelial basement membrane limits tip cell formation by inducing Dll4/Notch signalling in vivo.

PubMed

Stenzel, Denise; Franco, Claudio A; Estrach, Soline; Mettouchi, Amel; Sauvaget, Dominique; Rosewell, Ian; Schertel, Andreas; Armer, Hannah; Domogatskaya, Anna; Rodin, Sergey; Tryggvason, Karl; Collinson, Lucy; Sorokin, Lydia; Gerhardt, Holger

2011-10-28

How individual components of the vascular basement membrane influence endothelial cell behaviour remains unclear. Here we show that laminin α4 (Lama4) regulates tip cell numbers and vascular density by inducing endothelial Dll4/Notch signalling in vivo. Lama4 deficiency leads to reduced Dll4 expression, excessive filopodia and tip cell formation in the mouse retina, phenocopying the effects of Dll4/Notch inhibition. Lama4-mediated Dll4 expression requires a combination of integrins in vitro and integrin β1 in vivo. We conclude that appropriate laminin/integrin-induced signalling is necessary to induce physiologically functional levels of Dll4 expression and regulate branching frequency during sprouting angiogenesis in vivo.

Endothelial basement membrane limits tip cell formation by inducing Dll4/Notch signalling in vivo

PubMed Central

Stenzel, Denise; Franco, Claudio A; Estrach, Soline; Mettouchi, Amel; Sauvaget, Dominique; Rosewell, Ian; Schertel, Andreas; Armer, Hannah; Domogatskaya, Anna; Rodin, Sergey; Tryggvason, Karl; Collinson, Lucy; Sorokin, Lydia; Gerhardt, Holger

2011-01-01

How individual components of the vascular basement membrane influence endothelial cell behaviour remains unclear. Here we show that laminin α4 (Lama4) regulates tip cell numbers and vascular density by inducing endothelial Dll4/Notch signalling in vivo. Lama4 deficiency leads to reduced Dll4 expression, excessive filopodia and tip cell formation in the mouse retina, phenocopying the effects of Dll4/Notch inhibition. Lama4-mediated Dll4 expression requires a combination of integrins in vitro and integrin β1 in vivo. We conclude that appropriate laminin/integrin-induced signalling is necessary to induce physiologically functional levels of Dll4 expression and regulate branching frequency during sprouting angiogenesis in vivo. PMID:21979816

The Role of Progesterone and a Novel Progesterone Receptor, Progesterone Receptor Membrane Component 1, in the Inflammatory Response of Fetal Membranes to Ureaplasma parvum Infection.

PubMed

Feng, Liping; Ransom, Carla E; Nazzal, Matthew K; Allen, Terrence K; Li, Yi-Ju; Truong, Tracy; Potts, Lauren C; Seed, Patrick C; Murtha, Amy P

2016-01-01

Ureaplasma parvum (U. parvum) is gaining recognition as an important pathogen for chorioamnionitis and preterm premature rupture of membranes. We aimed to investigate the roles of progesterone (P4) and a novel progesterone receptor, progesterone receptor membrane component 1 (PGRMC1), in the response of fetal membranes to U. parvum. Fetal membrane cells (amnion, chorion and decidua) were isolated and confirmed to be free of Mycoplasmataceae. Cells were treated with U. parvum (5x106 CFU), and adherence was quantified by qPCR. Amnion and chorion cells were transfected with scrambled siRNA or validated PGRMC1 siRNA for 72h. Cells were then treated with U. parvum for 4h with or without pretreatment with P4 (10-7 M) or ethanol for 1h. Interleukin-8 (IL-8), matrix metalloproteinase 9 (MMP9) and cyclooxygenase (COX-2) mRNA expression were quantified by qRT-PCR. Culture medium was harvested and analyzed for IL-8 and prostaglandin (PGE2) secretion by ELISA and MMP9 activity by zymography. U. parvum had a mean adherence of 15.0±0.6%, 16.9± 3.7% and 4.7±0.3% in cultured amnion, chorion and decidua cells, respectively. Exposure to U. parvum elicited significant inflammatory responses including induction of IL-8, COX-2, PGE2 and MMP9. A possible role of PGRMC1 was identified in the inhibition of U. parvum-stimulated COX-2 and MMP9 mRNA expression in chorion cells and MMP9 activity in amnion cells. On the other hand, it might enhance the U. parvum-stimulated IL-8 protein secretion in amnion cells. P4, mediated through PGRMC1, significantly inhibited U. Parvum-induced MMP9 mRNA and COX-2 mRNA expression in chorion cells. P4 appeared to attenuate U. parvum induced IL-8 mRNA expression in chorion cells, but this P4 effect might not mediated through PGRMC1. In summary, U. parvum preferentially adheres to and induces inflammatory responses in chorion and amnion cells. P4 and PGRMC1 appear to differentially modulate the inflammatory responses induced by U. parvum among amnion and chorion cells.

Polarized targeting of a shaker-like (A-type) K(+)-channel in the polarized epithelial cell line MDCK.

PubMed

Le Maout, S; Sewing, S; Coudrier, E; Elalouf, J M; Pongs, O; Merot, J

1996-01-01

Functional Kv 1-4 channels were stably expressed in filter-grown MDCK cells which form a polarized epithelium with two distinct plasma membrane domains: a basolateral and an apical cell surface. The Shaker-related Kv 1-4 channels mediated in MDCK cells fast transient (A-type) voltage-activated outward currents having similar properties to the ones reported for Kv 1-4 in the Xenopus oocytes expression system. Immunoblot analysis with specific anti-Kv 1-4 antibodies showed that two Kv 1-4 protein forms are expressed in MDCK cells which most likely represent the glycosylated and non-glycosylated Kv 1-4 protein, respectively. Using immunocytochemistry and confocal microscopy we showed that the Kv 1-4 channels are specifically localized in the basolateral membranes of MDCK cells. Thus, the MDCK cells may provide an important model system to analyse the polarized transport of ion channels such as Kv 1-4, which are distinctly expressed in the mammalian central nervous system.

Formin like 1 expression is increased on CD4+ T lymphocytes in spontaneous autoimmune uveitis.

PubMed

Degroote, Roxane L; Uhl, Patrizia B; Amann, Barbara; Krackhardt, Angela M; Ueffing, Marius; Hauck, Stefanie M; Deeg, Cornelia A

2017-02-10

The membrane protein expression repertoire of cells changes in course of activation. In equine recurrent uveitis (ERU), a spontaneous autoimmune disease in horses with relapsing and ultimately blinding inner eye inflammation, CD4+ T lymphocytes are the crucial pathogenic cells activated in the periphery directly prior to an inflammatory episode. In order to find relevant changes in the membrane proteome associated to disease, we sorted CD4+ lymphocytes and compared protein abundance from the generated proteome datasets of both healthy horses and ERU cases. We detected formin like 1, a key player in actin dependent cellular processes such as phagocytosis, cell adhesion and cell migration, with significantly higher abundance in the CD4+ cell membrane proteome of horses with ERU. In transmigration experiments, we demonstrated higher migration rate of cells originating from diseased animals connecting formin like 1 to the migratory ability of cells. These findings are the first description of formin like 1 in association to processes involved in migration of inflammatory CD4+ T cells across the blood-retinal barrier in a spontaneous ocular autoimmune disease and suggest formin like 1 to play a role in the molecular mechanisms of ERU disease pathogenesis. Data are available via ProteomeXchange with identifier PXD005384. This comparative proteomic study of membrane proteins of CD4+ T cells identified a novel protein, formin like 1, with expression on the plasma cell membrane of equine CD4+ T cells and a significant change of abundance on CD4+ T cells of horses with a spontaneous autoimmune disease. Functional studies in a cell culture model for transmigration at the blood-retinal barrier (BRB) unraveled a strong impact of formin like 1 on migratory processes of CD4+ T cells across the BRB, a key event in uveitis pathogenesis. These findings provide novel knowledge about changes in the CD4+ immune cell membrane proteome in a spontaneously and naturally occurring autoimmune disease in horses with high relevance for veterinary medicine. Additionally, this model has proven translational quality for human medicine and provides novel proteomic information on autoimmune uveitis in man. Copyright © 2017 Elsevier B.V. All rights reserved.

Rho GTPase activity modulates paramyxovirus fusion protein-mediated cell-cell fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schowalter, Rachel M.; Wurth, Mark A.; Aguilar, Hector C.

2006-07-05

The paramyxovirus fusion protein (F) promotes fusion of the viral envelope with the plasma membrane of target cells as well as cell-cell fusion. The plasma membrane is closely associated with the actin cytoskeleton, but the role of actin dynamics in paramyxovirus F-mediated membrane fusion is unclear. We examined cell-cell fusion promoted by two different paramyxovirus F proteins in three cell types in the presence of constitutively active Rho family GTPases, major cellular coordinators of actin dynamics. Reporter gene and syncytia assays demonstrated that expression of either Rac1{sup V12} or Cdc42{sup V12} could increase cell-cell fusion promoted by the Hendra ormore » SV5 glycoproteins, though the effect was dependent on the cell type expressing the viral glycoproteins. In contrast, RhoA{sup L63} decreased cell-cell fusion promoted by Hendra glycoproteins but had little affect on SV5 F-mediated fusion. Also, data suggested that GTPase activation in the viral glycoprotein-containing cell was primarily responsible for changes in fusion. Additionally, we found that activated Cdc42 promoted nuclear rearrangement in syncytia.« less

Plasma membrane cholesterol level and agonist-induced internalization of δ-opioid receptors; colocalization study with intracellular membrane markers of Rab family.

PubMed

Brejchova, Jana; Vosahlikova, Miroslava; Roubalova, Lenka; Parenti, Marco; Mauri, Mario; Chernyavskiy, Oleksandr; Svoboda, Petr

2016-08-01

Decrease of cholesterol level in plasma membrane of living HEK293 cells transiently expressing FLAG-δ-OR by β-cyclodextrin (β-CDX) resulted in a slight internalization of δ-OR. Massive internalization of δ-OR induced by specific agonist DADLE was diminished in cholesterol-depleted cells. These results suggest that agonist-induced internalization of δ-OR, which has been traditionally attributed exclusively to clathrin-mediated pathway, proceeds at least partially via membrane domains. Identification of internalized pools of FLAG-δ-OR by colocalization studies with proteins of Rab family indicated the decreased presence of receptors in early endosomes (Rab5), late endosomes and lysosomes (Rab7) and fast recycling vesicles (Rab4). Slow type of recycling (Rab11) was unchanged by cholesterol depletion. As expected, agonist-induced internalization of oxytocin receptors was totally suppressed in β-CDX-treated cells. Determination of average fluorescence lifetime of TMA-DPH, the polar derivative of hydrophobic membrane probe diphenylhexatriene, in live cells by FLIM indicated a significant alteration of the overall PM structure which may be interpreted as an increased "water-accessible space" within PM area. Data obtained by studies of HEK293 cells transiently expressing FLAG-δ-OR by "antibody feeding" method were extended by analysis of the effect of cholesterol depletion on distribution of FLAG-δ-OR in sucrose density gradients prepared from HEK293 cells stably expressing FLAG-δ-OR. Major part of FLAG-δ-OR was co-localized with plasma membrane marker Na,K-ATPase and β-CDX treatment resulted in shift of PM fragments containing both FLAG-δ-OR and Na,K-ATPase to higher density. Thus, the decrease in content of the major lipid constituent of PM resulted in increased density of resulting PM fragments.

Epithelial Membrane Protein-2 in Human Proliferative Vitreoretinopathy and Epiretinal Membranes.

PubMed

Telander, David G; Yu, Alfred K; Forward, Krisztina I; Morales, Shawn A; Morse, Lawrence S; Park, Susanna S; Gordon, Lynn K

2016-06-01

To determine the level of epithelial membrane protein-2 (EMP2) expression in preretinal membranes from surgical patients with proliferative vitreoretinopathy (PVR) or epiretinal membranes (ERMs). EMP2, an integrin regulator, is expressed in the retinal pigment epithelium and understanding EMP2 expression in human retinal disease may help determine whether EMP2 is a potential therapeutic target. Preretinal membranes were collected during surgical vitrectomies after obtaining consents. The membranes were fixed, processed, sectioned, and protein expression of EMP2 was evaluated by immunohistochemistry. The staining intensity (SI) and percentage of positive cells (PP) in membranes were compared by masked observers. Membranes were categorized by their cause and type including inflammatory and traumatic. All of the membranes stained positive for EMP2. Proliferative vitreoretinopathy-induced membranes (all causes) showed greater expression of EMP2 than ERMs with higher SI (1.81 vs. 1.38; P = 0.07) and PP (2.08 vs. 1.54; P = 0.09). However all the PVR subgroups had similar levels of EMP2 expression without statistically significant differences by Kruskal-Wallis test. Inflammatory PVR had higher expression of EMP2 than ERMs (SI of 2.58 vs. 1.38); however, this was not statistically significant. No correlation was found between duration of PVR membrane and EMP2 expression. EMP2 was detected by RT-PCR in all samples (n = 6) tested. All studied ERMs and PVR membranes express EMP2. Levels of EMP2 trended higher in all PVR subgroups than in ERMs, especially in inflammatory and traumatic PVR. Future studies are needed to determine the role of EMP2 in the pathogenesis and treatment of various retinal conditions including PVR.

Tracking Single Cells in Live Animals Using a Photoconvertible Near-Infrared Cell Membrane Label

PubMed Central

Wu, Juwell; Runnels, Judith M.; Turcotte, Raphaël; Celso, Cristina Lo; Scadden, David T.; Strom, Terry B.; Lin, Charles P.

2013-01-01

We describe a novel photoconversion technique to track individual cells in vivo using a commercial lipophilic membrane dye, DiR. We show that DiR exhibits a permanent fluorescence emission shift (photoconversion) after light exposure and does not reacquire the original color over time. Ratiometric imaging can be used to distinguish photoconverted from non-converted cells with high sensitivity. Combining the use of this photoconvertible dye with intravital microscopy, we tracked the division of individual hematopoietic stem/progenitor cells within the calvarium bone marrow of live mice. We also studied the peripheral differentiation of individual T cells by tracking the gain or loss of FoxP3-GFP expression, a marker of the immune suppressive function of CD4+ T cells. With the near-infrared photoconvertible membrane dye, the entire visible spectral range is available for simultaneous use with other fluorescent proteins to monitor gene expression or to trace cell lineage commitment in vivo with high spatial and temporal resolution. PMID:23990881

Tracking single cells in live animals using a photoconvertible near-infrared cell membrane label.

PubMed

Carlson, Alicia L; Fujisaki, Joji; Wu, Juwell; Runnels, Judith M; Turcotte, Raphaël; Spencer, Joel A; Celso, Cristina Lo; Scadden, David T; Strom, Terry B; Lin, Charles P

2013-01-01

We describe a novel photoconversion technique to track individual cells in vivo using a commercial lipophilic membrane dye, DiR. We show that DiR exhibits a permanent fluorescence emission shift (photoconversion) after light exposure and does not reacquire the original color over time. Ratiometric imaging can be used to distinguish photoconverted from non-converted cells with high sensitivity. Combining the use of this photoconvertible dye with intravital microscopy, we tracked the division of individual hematopoietic stem/progenitor cells within the calvarium bone marrow of live mice. We also studied the peripheral differentiation of individual T cells by tracking the gain or loss of FoxP3-GFP expression, a marker of the immune suppressive function of CD4(+) T cells. With the near-infrared photoconvertible membrane dye, the entire visible spectral range is available for simultaneous use with other fluorescent proteins to monitor gene expression or to trace cell lineage commitment in vivo with high spatial and temporal resolution.

MSE55, a Cdc42 effector protein, induces long cellular extensions in fibroblasts

PubMed Central

Burbelo, Peter D.; Snow, Dianne M.; Bahou, Wadie; Spiegel, Sarah

1999-01-01

Cdc42 is a member of the Rho GTPase family that regulates multiple cellular activities, including actin polymerization, kinase-signaling activation, and cell polarization. MSE55 is a nonkinase CRIB (Cdc42/Rac interactive-binding) domain-containing molecule of unknown function. Using glutathione S-transferase-capture experiments, we show that MSE55 binds to Cdc42 in a GTP-dependent manner. MSE55 binding to Cdc42 required an intact CRIB domain, because a MSE55 CRIB domain mutant no longer interacted with Cdc42. To study the function of MSE55 we transfected either wild-type MSE55 or a MSE55 CRIB mutant into mammalian cells. In Cos-7 cells, wild-type MSE55 localized at membrane ruffles and increased membrane actin polymerization, whereas expression of the MSE55 CRIB mutant showed fewer membrane ruffles. In contrast to these results, MSE55 induced the formation of long, actin-based protrusions in NIH 3T3 cells as detected by immunofluorescence and live-cell video microscopy. MSE55-induced protrusion formation was blocked by expression of dominant-negative N17Cdc42, but not by expression of dominant-negative N17Rac. These findings indicate that MSE55 is a Cdc42 effector protein that mediates actin cytoskeleton reorganization at the plasma membrane. PMID:10430899

Expression of membrane-associated mucins MUC1 and MUC4 in major human salivary glands.

PubMed

Liu, Bing; Lague, Jessica R; Nunes, David P; Toselli, Paul; Oppenheim, Frank G; Soares, Rodrigo V; Troxler, Robert F; Offner, Gwynneth D

2002-06-01

Mucins are high molecular weight glycoproteins secreted by salivary glands and epithelial cells lining the digestive, respiratory, and reproductive tracts. These glycoproteins, encoded in at least 13 distinct human genes, can be subdivided into gel-forming and membrane-associated forms. The gel-forming mucin MUC5B is secreted by mucous acinar cells in major and minor salivary glands, but little is known about the expression pattern of membrane-associated mucins. In this study, RT-PCR and Northern blotting demonstrated the presence of transcripts for MUC1 and MUC4 in both parotid and submandibular glands, and in situ hybridization localized these transcripts to epithelial cells lining striated and excretory ducts and in some serous acinar cells. The same cellular distribution was observed by immunohistochemistry. Soluble forms of both mucins were detected in parotid secretion after immunoprecipitation with mucin-specific antibodies. These studies have shown that membrane-associated mucins are produced in both parotid and submandibular glands and that they are expressed in different cell types than gel-forming mucins. Although the function of these mucins in the oral cavity remains to be elucidated, it is possible that they both contribute to the epithelial protective mucin layer and act as receptors initiating one or more intracellular signal transduction pathways.

Comparison of culture media indicates a role for autologous serum in enhancing phenotypic preservation of rabbit limbal stem cells in explant culture.

PubMed

Gürdal, Mehmet; Barut Selver, Özlem; Baysal, Kemal; Durak, İsmet

2018-04-01

In this study, we aimed to compare the effects of six different cell culture media and autologous serum (AS) on the phenotypic characteristics of rabbit limbal epithelial stem cells (LESC) cultivated on porous polyethylene terephthalate (PET) membranes. Limbal explants from rabbit corneas were grown on PET membrane inserts in five different media: DMEM-F12 with fetal bovine serum (FBS) (DMEM-F12-FBS), with pluripotin (DMEM-F12-pluripotin) and with autologous serum (DMEM-F12-AS), Epilife, Keratinocyte Serum Free Medium (KSFM) and Defined-Keratinocyte Serum Free Medium. The effects of different media were evaluated by total cell yield from explants, measuring the expression of proteins by immunofluorescence and gene expression by Real Time PCR. In all five media tested, most of the limbal epithelial cells (LEC) which proliferated from explants were positive for cytokeratin (CK) 14 (85-90%), indicating that all five media support the growth of LESC from explants. The expression of differentiation markers; CK 3 and 12 was highest in DMEM-F12-FBS (56%), was lower in Epilife and KSFM (26 and 19%, respectively), with the lowest values (13%) obtained in DMEM-F12-AS. Gene expression of limbal cultures on PET membrane inserts was compared to fresh limbal tissue. In DMEM-F12-FBS, DMEM-F12-pluripotin, and DMEM-F12-AS, expression of potential LESC markers CXCR4 and polycomb complex protein BMI-1 were similar to limbal tissue. DMEM-F12 with 10% AS maintained a higher percentage of potential stem cell marker genes and lower expression of genes involved in differentiation compared to Epilife or KSFM. Our study shows that rabbit LEC can be cultivated on PET inserts using DMEM-F12 with autologous serum without a requirement for amniotic membrane or feeder cells.

Z-membranes: artificial organelles for overexpressing recombinant integral membrane proteins.

PubMed Central

Gong, F C; Giddings, T H; Meehl, J B; Staehelin, L A; Galbraith, D W

1996-01-01

We have expressed a fusion protein formed between the avian infectious bronchitis virus M protein and the bacterial enzyme beta-glucuronidase in transgenic tobacco cells. Electron microscope images of such cells demonstrate that overexpression of this fusion protein gives rise to a type of endoplasmic reticulum membrane domain in which adjacent membranes become zippered together apparently as a consequence of the oligomerizing action of beta-glucuronidase. These zippered (Z-) membranes lack markers of the endoplasmic reticulum (NADH cytochrome c reductase and ribosomes) and accumulate in the cells in the form of multilayered scroll-like structures (up to 2 micrometers in diameter; 20-50 per cell) without affecting plant growth. The discovery of Z-membranes has broad implications for biology and biotechnology in that they provide a means for accumulating large quantities of recombinant membrane proteins within discrete domains of native membranes. Images Fig. 1 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:8700911

Screening and large-scale expression of membrane proteins in mammalian cells for structural studies.

PubMed

Goehring, April; Lee, Chia-Hsueh; Wang, Kevin H; Michel, Jennifer Carlisle; Claxton, Derek P; Baconguis, Isabelle; Althoff, Thorsten; Fischer, Suzanne; Garcia, K Christopher; Gouaux, Eric

2014-11-01

Structural, biochemical and biophysical studies of eukaryotic membrane proteins are often hampered by difficulties in overexpression of the candidate molecule. Baculovirus transduction of mammalian cells (BacMam), although a powerful method to heterologously express membrane proteins, can be cumbersome for screening and expression of multiple constructs. We therefore developed plasmid Eric Gouaux (pEG) BacMam, a vector optimized for use in screening assays, as well as for efficient production of baculovirus and robust expression of the target protein. In this protocol, we show how to use small-scale transient transfection and fluorescence-detection size-exclusion chromatography (FSEC) experiments using a GFP-His8-tagged candidate protein to screen for monodispersity and expression level. Once promising candidates are identified, we describe how to generate baculovirus, transduce HEK293S GnTI(-) (N-acetylglucosaminyltransferase I-negative) cells in suspension culture and overexpress the candidate protein. We have used these methods to prepare pure samples of chicken acid-sensing ion channel 1a (cASIC1) and Caenorhabditis elegans glutamate-gated chloride channel (GluCl) for X-ray crystallography, demonstrating how to rapidly and efficiently screen hundreds of constructs and accomplish large-scale expression in 4-6 weeks.

Antimicrobial effect and membrane-active mechanism of tea polyphenols against Serratia marcescens.

PubMed

Yi, Shumin; Wang, Wei; Bai, Fengling; Zhu, Junli; Li, Jianrong; Li, Xuepeng; Xu, Yongxia; Sun, Tong; He, Yutang

2014-02-01

In this study, we investigated the antimicrobial effect of tea polyphenols (TP) against Serratia marcescens and examined the related mechanism. Morphology changes of S. marcescens were first observed by transmission electron microscopy after treatment with TP, which indicated that the primary inhibition action of TP was to damage the bacterial cell membranes. The permeability of the outer and inner membrane of S. marcescens dramatically increased after TP treatment, which caused severe disruption of cell membrane, followed by the release of small cellular molecules. Furthermore, a proteomics approach based on two-dimensional gel electrophoresis and MALDI-TOF/TOF MS analysis was used to study the difference of membrane protein expression in the control and TP treatment S. marcescens. The results showed that the expression of some metabolism enzymes and chaperones in TP-treated S. marcescens significantly increased compared to the untreated group, which might result in the metabolic disorder of this bacteria. Taken together, our results first demonstrated that TP had a significant growth inhibition effect on S. marcescens through cell membrane damage.

TRPV2 expression in rat oral mucosa.

PubMed

Shimohira, Daiji; Kido, Mizuho A; Danjo, Atsushi; Takao, Tomoka; Wang, Bing; Zhang, Jing-Qi; Yamaza, Takayoshi; Masuko, Sadahiko; Goto, Masaaki; Tanaka, Teruo

2009-10-01

The oral mucosa is a highly specialised, stratified epithelium that confers protection from infection and physical, chemical and thermal stimuli. The non-keratinised junctional epithelium surrounds each tooth like a collar and is easily attacked by foreign substances from the oral sulcus. We found that TRPV2, a temperature-gated channel, is highly expressed in junctional epithelial cells, but not in oral sulcular epithelial cells or oral epithelial cells. Dual or triple immunolabelling with immunocompetent cell markers also revealed TRPV2 expression in Langerhans cells and in dendritic cells and macrophages. Electron microscopy disclosed TRPV2 immunoreactivity in the unmyelinated and thinly myelinated axons within the connective tissue underlying the epithelium. TRPV2 labelling was also observed in venule endothelial cells. The electron-dense immunoreaction in junctional epithelial cells, macrophages and neural axons occurred on the plasma membrane, on invaginations of the plasma membrane and in vesicular structures. Because TRPV2 has been shown to respond to temperature, hypotonicity and mechanical stimuli, gingival cells expressing TRPV2 may act as sensor cells, detecting changes in the physical and chemical environment, and may play a role in subsequent defence mechanisms.

Expression of complement membrane regulators membrane cofactor protein (CD46), decay accelerating factor (CD55), and protectin (CD59) in human malignant gliomas.

PubMed Central

Mäenpää, A.; Junnikkala, S.; Hakulinen, J.; Timonen, T.; Meri, S.

1996-01-01

Gliomas are malignant brain tumors, which, despite recent progress in surgical and radiological treatment, still have a poor prognosis. Since gliomas apparently resist immunological clearance mechanisms, we became interested in examining bow gliomas resist killing by the human complement system. The resistance of human cells to complement-mediated damage is, in large part, mediated by specific inhibitors of complement:membrane cofactor protein (CD46), decay-accelerating factor (CD55), and protectin (CD59). In the present study we examined the expression of complement regulators in 14 human glioma tumors and in 7 glioma cell lines (U251, U87, HS683, U373, U138, U118, and H2). Protectin was found to be strongly expressed by all glioma tumors and cell lines. Northern blotting analysis demonstrated the typical pattern of four to five protectin mRNAs in the glioma cells. Except for blood vessels, the expression of decay-accelerating factor was weak or absent in the tumors in situ, whereas in the cell lines its expression varied, ranging from negative to intermediate. Membrane cofactor protein was moderately expressed by all the cell lines but only weakly in the tumors. Cell-killing experiments demonstrated that the glioma cell lines were exceptionally resistant to C-mediated lysis. Five of the seven cell lines (U373, HS683, U118, U138, and H2) resisted complement lysis under conditions where most other cell lines were sensitive to killing. Neutralization experiments using specific monoclonal antibodies indicated that protectin was functionally the most important complement regulator in the glioma cells. The killing of the U87 and U251 cells could be significantly increased by a blocking anti-protectin monoclonal antibody, whereas for the other cell lines only moderate or no response was observed. The H2 cell line resisted killing by all antibodies and by complement. These results show that protectin is the most important complement regulator on human glioma cells. The exceptional complement resistance of some glioma cell lines suggests that they may utilize other, hitherto less well characterized, mechanisms to resist complement killing. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 PMID:8644856

Impact of Hybrid and Complex N-Glycans on Cell Surface Targeting of the Endogenous Chloride Cotransporter Slc12a2

PubMed Central

Singh, Richa; Pacheco-Andrade, Romario; Almiahuob, Mohamed Y. Mahmoud

2015-01-01

The Na+K+2Cl− cotransporter-1 (Slc12a2, NKCC1) is widely distributed and involved in cell volume/ion regulation. Functional NKCC1 locates in the plasma membrane of all cells studied, particularly in the basolateral membrane of most polarized cells. Although the mechanisms involved in plasma membrane sorting of NKCC1 are poorly understood, it is assumed that N-glycosylation is necessary. Here, we characterize expression, N-glycosylation, and distribution of NKCC1 in COS7 cells. We show that ~25% of NKCC1 is complex N-glycosylated whereas the rest of it corresponds to core/high-mannose and hybrid-type N-glycosylated forms. Further, ~10% of NKCC1 reaches the plasma membrane, mostly as core/high-mannose type, whereas ~90% of NKCC1 is distributed in defined intracellular compartments. In addition, inhibition of the first step of N-glycan biosynthesis with tunicamycin decreases total and plasma membrane located NKCC1 resulting in almost undetectable cotransport function. Moreover, inhibition of N-glycan maturation with swainsonine or kifunensine increased core/hybrid-type NKCC1 expression but eliminated plasma membrane complex N-glycosylated NKCC1 and transport function. Together, these results suggest that (i) NKCC1 is delivered to the plasma membrane of COS7 cells independently of its N-glycan nature, (ii) most of NKCC1 in the plasma membrane is core/hybrid-type N-glycosylated, and (iii) the minimal proportion of complex N-glycosylated NKCC1 is functionally active. PMID:26351455

Effects of recombinant protein misfolding and aggregation on bacterial membranes.

PubMed

Ami, D; Natalello, A; Schultz, T; Gatti-Lafranconi, P; Lotti, M; Doglia, S M; de Marco, A

2009-02-01

The expression of recombinant proteins is known to induce a metabolic rearrangement in the host cell. We used aggregation-sensitive model systems to study the effects elicited in Escherichia coli cells by the aggregation of recombinant glutathione-S-transferase and its fusion with the green fluorescent protein that, according to the expression conditions, accumulate intracellularly as soluble protein, or soluble and insoluble aggregates. We show that the folding state of the recombinant protein and the complexity of the intracellular aggregates critically affect the cell response. Specifically, protein misfolding and aggregation induce changes in specific host proteins involved in lipid metabolism and oxidative stress, a reduction in the membrane permeability, as well as a rearrangement of its lipid composition. The temporal evolution of the host cell response and that of the aggregation process pointed out that the misfolded protein and soluble aggregates are responsible for the membrane modifications and the changes in the host protein levels. Interestingly, native recombinant protein and large insoluble aggregates do not seem to activate stress markers and membrane rearrangements.

Single-Molecule Imaging of Wnt3A Protein Diffusion on Living Cell Membranes.

PubMed

Lippert, Anna; Janeczek, Agnieszka A; Fürstenberg, Alexandre; Ponjavic, Aleks; Moerner, W E; Nusse, Roel; Helms, Jill A; Evans, Nicholas D; Lee, Steven F

2017-12-19

Wnt proteins are secreted, hydrophobic, lipidated proteins found in all animals that play essential roles in development and disease. Lipid modification is thought to facilitate the interaction of the protein with its receptor, Frizzled, but may also regulate the transport of Wnt protein and its localization at the cell membrane. Here, by employing single-molecule fluorescence techniques, we show that Wnt proteins associate with and diffuse on the plasma membranes of living cells in the absence of any receptor binding. We find that labeled Wnt3A transiently and dynamically associates with the membranes of Drosophila Schneider 2 cells, diffuses with Brownian kinetics on flattened membranes and on cellular protrusions, and does not transfer between cells in close contact. In S2 receptor-plus (S2R+) cells, which express Frizzled receptors, membrane diffusion rate is reduced and membrane residency time is increased. These results provide direct evidence of Wnt3A interaction with living cell membranes, and represent, to our knowledge, a new system for investigating the dynamics of Wnt transport. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Ebola virus requires a host scramblase for externalization of phosphatidylserine on the surface of viral particles.

PubMed

Nanbo, Asuka; Maruyama, Junki; Imai, Masaki; Ujie, Michiko; Fujioka, Yoichiro; Nishide, Shinya; Takada, Ayato; Ohba, Yusuke; Kawaoka, Yoshihiro

2018-01-01

Cell surface receptors for phosphatidylserine contribute to the entry of Ebola virus (EBOV) particles, indicating that the presence of phosphatidylserine in the envelope of EBOV is important for the internalization of EBOV particles. Phosphatidylserine is typically distributed in the inner layer of the plasma membrane in normal cells. Progeny virions bud from the plasma membrane of infected cells, suggesting that phosphatidylserine is likely flipped to the outer leaflet of the plasma membrane in infected cells for EBOV virions to acquire it. Currently, the intracellular dynamics of phosphatidylserine during EBOV infection are poorly understood. Here, we explored the role of XK-related protein (Xkr) 8, which is a scramblase responsible for exposure of phosphatidylserine in the plasma membrane of apoptotic cells, to understand its significance in phosphatidylserine-dependent entry of EBOV. We found that Xkr8 and transiently expressed EBOV glycoprotein GP often co-localized in intracellular vesicles and the plasma membrane. We also found that co-expression of GP and viral major matrix protein VP40 promoted incorporation of Xkr8 into ebolavirus-like particles (VLPs) and exposure of phosphatidylserine on their surface, although only a limited amount of phosphatidylserine was exposed on the surface of the cells expressing GP and/or VP40. Downregulating Xkr8 or blocking caspase-mediated Xkr8 activation did not affect VLP production, but they reduced the amount of phosphatidylserine on the VLPs and their uptake in recipient cells. Taken together, our findings indicate that Xkr8 is trafficked to budding sites via GP-containing vesicles, is incorporated into VLPs, and then promote the entry of the released EBOV to cells in a phosphatidylserine-dependent manner.

Ebola virus requires a host scramblase for externalization of phosphatidylserine on the surface of viral particles

PubMed Central

Imai, Masaki; Ujie, Michiko; Fujioka, Yoichiro; Nishide, Shinya; Takada, Ayato; Ohba, Yusuke; Kawaoka, Yoshihiro

2018-01-01

Cell surface receptors for phosphatidylserine contribute to the entry of Ebola virus (EBOV) particles, indicating that the presence of phosphatidylserine in the envelope of EBOV is important for the internalization of EBOV particles. Phosphatidylserine is typically distributed in the inner layer of the plasma membrane in normal cells. Progeny virions bud from the plasma membrane of infected cells, suggesting that phosphatidylserine is likely flipped to the outer leaflet of the plasma membrane in infected cells for EBOV virions to acquire it. Currently, the intracellular dynamics of phosphatidylserine during EBOV infection are poorly understood. Here, we explored the role of XK-related protein (Xkr) 8, which is a scramblase responsible for exposure of phosphatidylserine in the plasma membrane of apoptotic cells, to understand its significance in phosphatidylserine-dependent entry of EBOV. We found that Xkr8 and transiently expressed EBOV glycoprotein GP often co-localized in intracellular vesicles and the plasma membrane. We also found that co-expression of GP and viral major matrix protein VP40 promoted incorporation of Xkr8 into ebolavirus-like particles (VLPs) and exposure of phosphatidylserine on their surface, although only a limited amount of phosphatidylserine was exposed on the surface of the cells expressing GP and/or VP40. Downregulating Xkr8 or blocking caspase-mediated Xkr8 activation did not affect VLP production, but they reduced the amount of phosphatidylserine on the VLPs and their uptake in recipient cells. Taken together, our findings indicate that Xkr8 is trafficked to budding sites via GP-containing vesicles, is incorporated into VLPs, and then promote the entry of the released EBOV to cells in a phosphatidylserine-dependent manner. PMID:29338048

Regulated expression of the rat recombinant P2X(3) receptor in stably transfected CHO-K1 tTA cells.

PubMed

Lachnit, W G; Oglesby, I B; Gever, J R; Gever, M; Huang, C; Li, X C; Jin, H; McGivern, J G; Ford, A P

2000-07-03

In this report, the regulatable expression by tetracycline of the rat recombinant P2X(3) receptor in stably transfected Chinese hamster ovary (CHO-K1) expressing the tetracycline-controlled transactivator (tTA) is described. cDNA encoding the rat P2X(3)-receptor was subcloned into pTRE (a tetracycline-repressible expression vector) which was used to transfect stably CHO-K1 tTA cells. Using whole cell patch clamp techniques, 100 microM ATP evoked inward currents of 2.9+/-1.6 nA in transfected cells grown in the absence of tetracycline (tet-). The P2X(3) receptor protein was detectable by immunoblot as early as 24 h and protein expression levels continued to increase as much as 192 h following activation of tTA by the removal of the antibiotic. Saturation binding isotherms using [35S]ATP gamma S yielded a pK(d) of 8.2+/-0.1 and a B(max) of 31.9+/-3.5 pmol/mg protein in tet- cell membranes and a pK(d) of 8.1+/-0.1 and a B(max) of 5.8+/-0.8 pmol/mg protein in tet+ cell membranes. The agonist ligands 2MeSATP and alpha beta MeATP displaced the binding of [35S]ATP gamma S in tet- cell membranes with very high affinity, yielding pIC(50) values of 9.4+/-0.2 and 7.5+/-0. 2, respectively. In tet+ cell membrane, displacement of [35S]ATP gamma S by 2MeSATP and alpha beta MeATP was of much lower affinity (pIC(50) values of 7.8 and 6.2, respectively). ATP, ADP and UTP showed similar displacement of [35S]ATP gamma S binding in tet- and tet+ cell membranes. In other experiments, cytosolic Ca(2+) was monitored using the fluorescent indicator, fluo-3. Increases in cytosolic Ca(2+) were elicited by 100 nM alpha beta MeATP in tet- cells while no increases in cytosolic Ca(2+) were detected below 100 microM alpha beta MeATP in either tet+ cells or untransfected cells. These calcium responses to alpha beta MeATP had a pEC(50) of 6.7 and were transient, returning to baseline within 120 s. Suramin produced concentration-dependent, parallel, dextral shifts of E/[A] curves to alpha beta MeATP yielding a pK(B) of 5.6. PPADS produced non-parallel, dextral shifts of E/[A] curves to alpha beta MeATP which were insurmountable. These results show for the first time, expression of a functional, homomeric recombinant rat P2X(3) receptor which is under regulated expression in a stably transfected mammalian cell line.

The establishment of polarized membrane traffic in Xenopus laevis embryos.

PubMed

Roberts, S J; Leaf, D S; Moore, H P; Gerhart, J C

1992-09-01

Delineation of apical and basolateral membrane domains is a critical step in the epithelialization of the outer layer of cells in the embryo. We have examined the initiation of polarized membrane traffic in Xenopus and show that membrane traffic is not polarized in oocytes but polarized membrane domains appear at first cleavage. The following proteins encoded by injected RNA transcripts were used as markers to monitor membrane traffic: (a) VSV G, a transmembrane glycoprotein preferentially inserted into the basolateral surface of polarized epithelial cells; (b) GThy-1, a fusion protein of VSV G and Thy-1 that is localized to the apical domains of polarized epithelial cells; and (c) prolactin, a peptide hormone that is not polarly secreted. In immature oocytes, there is no polarity in the expression of VSV G or GThy-1, as shown by the constitutive expression of both proteins at the surface in the animal and vegetal hemispheres. At meiotic maturation, membrane traffic to the surface is blocked; the plasma membrane no longer accepts the vesicles synthesized by the oocyte (Leaf, D. L., S. J. Roberts, J. C. Gerhart, and H.-P. Moore. 1990. Dev. Biol. 141:1-12). When RNA transcripts are injected after fertilization, VSV G is expressed only in the internal cleavage membranes (basolateral orientation) and is excluded from the outer surface (apical orientation, original oocyte membrane). In contrast, GThy-1 and prolactin, when expressed in embryos, are inserted or released at both the outer membrane derived from the oocyte and the inner cleavage membranes. Furthermore, not all of the cleavage membrane comes from an embryonic pool of vesicles--some of the cleavage membrane comes from vesicles synthesized during oogenesis. Using prolactin as a marker, we found that a subset of vesicles synthesized during oogenesis was only released after fertilization. However, while embryonic prolactin was secreted from both apical and basolateral surfaces, the secretion of oogenic prolactin was polarized. Oogenic prolactin was secreted only into the blastocoel (from the cleavage membrane), none could be detected in the external medium (from the original oocyte membrane). These results provide the first direct evidence that the oocyte synthesizes a cache of vesicles for specific recruitment to the embryonic cleavage membranes which are polarized beginning with the first cleavage division.

New insights into enterocin CRL35: mechanism of action and immunity revealed by heterologous expression in Escherichia coli.

PubMed

Barraza, Daniela E; Ríos Colombo, Natalia S; Galván, Adriana E; Acuña, Leonardo; Minahk, Carlos J; Bellomio, Augusto; Chalón, Miriam C

2017-09-01

The role of the class IIa bacteriocin membrane receptor protein remains unclear, and the following two different mechanisms have been proposed: the bacteriocin could interact with the receptor changing it to an open conformation or the receptor might act as an anchor allowing subsequent bacteriocin insertion and membrane disruption. Bacteriocin-producing cells synthesize an immunity protein that forms an inactive bacteriocin-receptor-immunity complex. To better understand the molecular mechanism of enterocin CRL35, the peptide was expressed as the suicidal probe EtpM-enterocin CRL35 in Escherichia coli, a naturally insensitive microorganism since it does not express the receptor. When the bacteriocin is anchored to the periplasmic face of the plasma membrane through the bitopic membrane protein, EtpM , E. coli cells depolarize and die. Moreover, co-expression of the immunity protein prevents the deleterious effect of EtpM-enterocin CRL35. The binding and anchoring of the bacteriocin to the membrane has demonstrated to be a sufficient condition for its membrane insertion. The final step of membrane disruption by EtpM-enterocin CRL35 is independent from the receptor, which means that the mannose PTS might not be involved in the pore structure. In addition, the immunity protein can protect even in the absence of the receptor. © 2017 John Wiley & Sons Ltd.

Expression of G protein estrogen receptor (GPER) on membrane of mouse oocytes during maturation.

PubMed

Li, Yi-Ran; Ren, Chun-E; Zhang, Quan; Li, Ji-Chun; Chian, Ri-Cheng

2013-02-01

To determine expression of G-protein estrogen receptor (GPER) in mouse oocyte membrane during maturation. The expression of GPER from different maturation stages of oocytes, in vivo and in vitro matured oocytes as well as aging oocytes was examined by immune-fluorescence GPR30 antibody and the images were analyzed by laser scanning confocal microscope. Further confirmation was performed by Western blots for cell fractionation. Significant fluorescent signal was observed on the surface of mouse oocytes. The image expression was lower in germinal vesicle (GV) stage than mature metaphase-II (M-II) stage oocytes. There was high expression in in-vivo matured oocytes compared to in vitro matured oocytes. The highest expression was observed in aging oocytes compared with other oocytes. The changes of expression of GPER on mouse oocytes plasma membrane confirm oocyte membrane maturation, suggesting that those changes of GPER may be related to the functional role of oocyte maturation.

Effect of therapeutic concentration of lithium on live HEK293 cells; increase of Na+/K+-ATPase, change of overall protein composition and alteration of surface layer of plasma membrane.

PubMed

Vosahlikova, Miroslava; Ujcikova, Hana; Chernyavskiy, Oleksandr; Brejchova, Jana; Roubalova, Lenka; Alda, Martin; Svoboda, Petr

2017-05-01

The effect of long-term exposure of live cells to lithium cations (Li) was studied in HEK293 cells cultivated in the presence of 1mM LiCl for 7 or 21days. The alteration of Na + /K + -ATPase level, protein composition and biophysical state of plasma membrane was determined with the aim to characterize the physiological state of Li-treated cells. Na + /K + -ATPase level was determined by [ 3 H]ouabain binding and immunoblot assays. Overall protein composition was determined by 2D electrophoresis followed by proteomic analysis by MALDI-TOF MS/MS and LFQ. Li interaction with plasma membrane was characterized by fluorescent probes DPH, TMA-DPH and Laurdan. Na + /K + -ATPase was increased in plasma membranes isolated from cells exposed to Li. Identification of Li-altered proteins by 2D electrophoresis, MALDI-TOF MS/MS and LFQ suggests a change of energy metabolism in mitochondria and cytosol and alteration of cell homeostasis of calcium. Measurement of Laurdan generalized polarization indicated a significant alteration of surface layer of isolated plasma membranes prepared from both types of Li-treated cells. Prolonged exposure of HEK293 cells to 1mM LiCl results in up-regulation of Na + /K + -ATPase expression, reorganization of overall cellular metabolism and alteration of the surface layer/polar head-group region of isolated plasma membranes. Our findings demonstrate adaptation of live HEK293 cell metabolism to prolonged exposure to therapeutic concentration of Li manifested as up-regulation of Na + /K + -ATPase expression, alteration of protein composition and change of the surface layer of plasma membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

Involvement of phosphoinositide 3-kinase and PTEN protein in mechanism of activation of TRPC6 protein in vascular smooth muscle cells.

PubMed

Monet, Michaël; Francoeur, Nancy; Boulay, Guylain

2012-05-18

TRPC6 is a cation channel in the plasma membrane that plays a role in Ca(2+) entry after the stimulation of a G(q)-protein-coupled or tyrosine-kinase receptor. TRPC6 translocates to the plasma membrane upon stimulation and remains there as long as the stimulus is present. However, the mechanism that regulates the trafficking and activation of TRPC6 are unclear. In this study we showed phosphoinositide 3-kinase and its antagonistic phosphatase, PTEN, are involved in the activation of TRPC6. The inhibition of PI3K by PIK-93, LY294002, or wortmannin decreased carbachol-induced translocation of TRPC6 to the plasma membrane and carbachol-induced net Ca(2+) entry into T6.11 cells. Conversely, a reduction of PTEN expression did not affect carbachol-induced externalization of TRPC6 but increased Ca(2+) entry through TRPC6 in T6.11 cells. We also showed that the PI3K/PTEN pathway regulates vasopressin-induced translocation of TRPC6 to the plasma membrane and vasopressin-induced Ca(2+) entry into A7r5 cells, which endogenously express TRPC6. In summary, we provided evidence that the PI3K/PTEN pathway plays an important role in the translocation of TRPC6 to the plasma membrane and may thus have a significant impact on Ca(2+) signaling in cells that endogenously express TRPC6.

Involvement of Phosphoinositide 3-Kinase and PTEN Protein in Mechanism of Activation of TRPC6 Protein in Vascular Smooth Muscle Cells*

PubMed Central

Monet, Michaël; Francoeur, Nancy; Boulay, Guylain

2012-01-01

TRPC6 is a cation channel in the plasma membrane that plays a role in Ca2+ entry after the stimulation of a Gq-protein-coupled or tyrosine-kinase receptor. TRPC6 translocates to the plasma membrane upon stimulation and remains there as long as the stimulus is present. However, the mechanism that regulates the trafficking and activation of TRPC6 are unclear. In this study we showed phosphoinositide 3-kinase and its antagonistic phosphatase, PTEN, are involved in the activation of TRPC6. The inhibition of PI3K by PIK-93, LY294002, or wortmannin decreased carbachol-induced translocation of TRPC6 to the plasma membrane and carbachol-induced net Ca2+ entry into T6.11 cells. Conversely, a reduction of PTEN expression did not affect carbachol-induced externalization of TRPC6 but increased Ca2+ entry through TRPC6 in T6.11 cells. We also showed that the PI3K/PTEN pathway regulates vasopressin-induced translocation of TRPC6 to the plasma membrane and vasopressin-induced Ca2+ entry into A7r5 cells, which endogenously express TRPC6. In summary, we provided evidence that the PI3K/PTEN pathway plays an important role in the translocation of TRPC6 to the plasma membrane and may thus have a significant impact on Ca2+ signaling in cells that endogenously express TRPC6. PMID:22493444

Immunohistochemical expression of E-cadherin does not distinguish canine cutaneous histiocytoma from other canine round cell tumors.

PubMed

Ramos-Vara, J A; Miller, M A

2011-05-01

Immunohistochemistry for E-cadherin (ECAD) has been used to distinguish canine cutaneous histiocytoma from other leukocytic neoplasms ("round cell tumors"). To determine the specificity of this test, 5 types of canine cutaneous round cell tumors were evaluated for immunohistochemical expression of ECAD. Tumors of all 5 types had variable cytoplasmic, plasma membrane, and/or paranuclear ECAD expression: All 13 cutaneous histiocytomas were ECAD+; all but 1 of 14 mast cell tumors expressed ECAD; 10 of 12 epitheliotropic lymphomas reacted with E-cadherin antibody; of 72 plasmacytomas, 54 were ECAD+; and 5 of 5 histiocytic sarcomas were positive. Conclusions based on these results include the following: First, immunoreactivity for ECAD is not limited to leukocytes of cutaneous histiocytoma; second, antibody to ECAD also labels neoplastic cells in most mast cell tumors, plasmacytomas, cutaneous histiocytic sarcomas, and epitheliotropic lymphomas; third, although most histiocytomas have membranous ECAD expression, the immunoreactivity varies among round cell tumors and is frequently concurrent in different cellular compartments; fourth, the distinctively paranuclear ECAD expression pattern in epitheliotropic lymphomas might distinguish them from other round cell tumors; and, fifth, ECAD should be used with other markers (eg, MUM1 for plasmacytomas, KIT for mast cell tumors, CD3 and CD79a for lymphomas) to distinguish among canine round cell tumors.

Expression of decay-accelerating factor (CD55), membrane cofactor protein (CD46) and CD59 in the human astroglioma cell line, D54-MG, and primary rat astrocytes.

PubMed

Yang, C; Jones, J L; Barnum, S R

1993-09-01

In this report, we have shown the expression of the complement regulatory proteins decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46) and CD59 on human D54-MG astroglioma cells by several methods, including immunofluorescence, flow cytometry and Western blotting and Northern blot analysis. These studies demonstrate that all three proteins are structurally and antigenically similar to their counterparts expressed on HepG2 and SW480 cells (hepatocyte and epithelial cell lines, respectively). D54-MG cells express mRNA for all three proteins of the appropriate size(s). The phosphatidylinositol-specific enzyme, PIPLC, cleaved DAF from the surface of D54-MG cells, demonstrating that DAF is linked by a glycophospholipid anchor as has been shown for other cell types. Flow cytometry demonstrates that primary rat astrocytes also constitutively express all three regulatory proteins. These data are the first to demonstrate the expression of CD59 on astrocytes, and the presence of all three regulatory proteins on astrocytes suggests that regulation of complement activation in the central nervous system is important in neural host defense mechanisms.

Cell membrane-bound CD200 signals both via an extracellular domain and following nuclear translocation of a cytoplasmic fragment.

PubMed

Chen, Zhiqi; Kapus, Andras; Khatri, Ismat; Kos, Olha; Zhu, Fang; Gorczynski, Reginald M

2018-06-01

In previous studies we had reported that the immunosuppressive cell membrane bound molecule CD200 is released from the cell following cleavage by matrix metalloproteases, with the released soluble CD200 acting as an immunosuppressant following binding to, and signaling through, its cognate receptor CD200R expressed on target cells. We now show that although the intracellular cytoplasmic tail (CD200 C-tail ) of CD200 has no consensus sites for adapter molecules which might signal the CD200 + cell directly, cleavage of the CD200 C-tail from the membrane region of CD200 by a consensus γ-secretase, leads to nuclear translocation and DNA binding (identified by chromatin immunoprecipitation followed by sequencing, Chip-sequencing) of the CD200 C-tail . Subsequently there occurs an altered expression of a limited number of genes, many of which are transcription factors (TFs) known to be associated with regulation of cell proliferation. Altered expression of these TFs was also prominent following transfection of CD200 + B cell lines and fresh patient CLL cells with a vector construct containing the CD200 C-tail . Artificial transfection of non CD200 + Hek293 cells with this CD200 C-tail construct resulted in altered expression of most of these same genes. Introduction of a siRNA for one of these TFs, POTEA, reversed CD200 C-tail regulation of altered cell proliferation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Susceptibility to virus-cell fusion at the plasma membrane is reduced through expression of HIV gp41 cytoplasmic domains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malinowsky, Katharina; Department of Virology, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg; Luksza, Julia

2008-06-20

The cytoplasmic tail of the HIV transmembrane protein plays an important role in viral infection. In this study we analyzed the role of retroviral cytoplasmic tails in modulating the cytoskeleton and interfering with virus-cell fusion. HeLaP4 cells expressing different HIV cytoplasmic tail constructs showed reduced acetylated tubulin levels whereas the cytoplasmic tail of MLV did not alter microtubule stability indicating a unique function for the lentiviral cytoplasmic tail. The effect on tubulin is mediated through the membrane proximal region of the HIV cytoplasmic tail and was independent of membrane localization. Site-directed mutagenesis identified three motifs in the HIV-2 cytoplasmic tailmore » required to effect the reduction in acetylated tubulin. Both the Yxx{phi} domain and amino acids 21 to 45 of the HIV-2 cytoplasmic tail need to be present to change the level of acetylated tubulin in transfected cells. T-cells stably expressing one HIV-2 cytoplasmic tail derived construct showed also a reduction in acetylated tubulin thus confirming the importance of this effect not only for HeLaP4 and 293T cells. Challenge experiments using transiently transfected HeLaP4 cells and T cells stably expressing an HIV cytoplasmic tail construct revealed both reduced virus-cell fusion and replication of HIV-1{sub NL4.3} compared to control cells. In the virus-cell fusion assay only virions pseudotyped with either HIV or MLV envelopes showed reduced fusion efficiency, whereas VSV-G pseudotyped virions where not affected by the expression of HIV derived cytoplasmic tail constructs, indicating that fusion at the plasma but not endosomal membrane is affected. Overexpression of human histone-deacetylase 6 (HDAC6) and constitutively active RhoA resulted in a reduction of acetylated tubulin and reduced virus-cell fusion as significant as that observed following expression of HIV cytoplasmic tail constructs. Inhibition of HDAC6 showed a strong increase in acetylated tubulin and increase of virus-cell fusion confirming the correlation between post-translational modification of tubulin and virus-cell fusion. These results thus identify tubulin and its post-translational modification as a new cellular target for interference with HIV-cell fusion.« less

Mitochondrial aquaporin-8 knockdown in human hepatoma HepG2 cells causes ROS-induced mitochondrial depolarization and loss of viability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchissio, Maria Julia; Francés, Daniel Eleazar Antonio; Carnovale, Cristina Ester

Human aquaporin-8 (AQP8) channels facilitate the diffusional transport of H{sub 2}O{sub 2} across membranes. Since AQP8 is expressed in hepatic inner mitochondrial membranes, we studied whether mitochondrial AQP8 (mtAQP8) knockdown in human hepatoma HepG2 cells impairs mitochondrial H{sub 2}O{sub 2} release, which may lead to organelle dysfunction and cell death. We confirmed AQP8 expression in HepG2 inner mitochondrial membranes and found that 72 h after cell transfection with siRNAs targeting two different regions of the human AQP8 molecule, mtAQP8 protein specifically decreased by around 60% (p < 0.05). Studies in isolated mtAQP8-knockdown mitochondria showed that H{sub 2}O{sub 2} release, assessedmore » by Amplex Red, was reduced by about 45% (p < 0.05), an effect not observed in digitonin-permeabilized mitochondria. mtAQP8-knockdown cells showed an increase in mitochondrial ROS, assessed by dichlorodihydrofluorescein diacetate (+ 120%, p < 0.05) and loss of mitochondrial membrane potential (− 80%, p < 0.05), assessed by tetramethylrhodamine-coupled quantitative fluorescence microscopy. The mitochondria-targeted antioxidant MitoTempol prevented ROS accumulation and dissipation of mitochondrial membrane potential. Cyclosporin A, a mitochondrial permeability transition pore blocker, also abolished the mtAQP8 knockdown-induced mitochondrial depolarization. Besides, the loss of viability in mtAQP8 knockdown cells verified by MTT assay, LDH leakage, and trypan blue exclusion test could be prevented by cyclosporin A. Our data on human hepatoma HepG2 cells suggest that mtAQP8 facilitates mitochondrial H{sub 2}O{sub 2} release and that its defective expression causes ROS-induced mitochondrial depolarization via the mitochondrial permeability transition mechanism, and cell death. -- Highlights: ► Aquaporin-8 is expressed in mitochondria of human hepatoma HepG2 cells. ► Aquaporin-8 knockdown impairs mitochondrial H{sub 2}O{sub 2} release and increases ROS. ► Aquaporin-8 knockdown causes ROS-induced mitochondrial depolarization and cell death. ► Mitochondrial permeability transition blockage prevents depolarization and cell death.« less

Unprecedented Cell-Selection Using Ultra-Quick Freezing Combined with Aquaporin Expression

PubMed Central

Kato, Yasuhiro; Miyauchi, Takayuki; Abe, Youichiro; Kojić, Dušan; Tanaka, Manami; Chikazawa, Nana; Nakatake, Yuhki; Ko, Shigeru B. H.; Kobayashi, Daisuke; Hazama, Akihiro; Fujiwara, Shoko; Uchida, Tatsuya; Yasui, Masato

2014-01-01

Freezing is usually used for preservation and storage of biological samples; however, this process may have some adverse effects such as cell membrane damage. Aquaporin (AQP), a water channel protein, has been suggested to play some roles for cryopreservation although its molecular mechanism remains unclear. Here we show that membrane damage caused by ultra-quick freezing is rescued by the expression of AQP4. We next examine if the expression of AQP combined with ultra-quick freezing can be used to select cells efficiently under freezing conditions where most cells are died. CHO cells stably expressing AQP4 were exclusively selected from mixed cell cultures. Having identified the increased expression of AQP4 during ES cell differentiation into neuro-ectoderm using bioinformatics, we confirmed the improved survival of differentiated ES cells with AQP4 expression. Finally we show that CHO cells transiently transfected with Endothelin receptor A and Aqp4 were also selected and concentrated by multiple cycles of freezing/thawing, which was confirmed with calcium imaging in response to endothelin. Furthermore, we found that the expression of AQP enables a reduction in the amount of cryoprotectants for freezing, thereby decreasing osmotic stress and cellular toxicity. Taken together, we propose that this simple but efficient and safe method may be applicable to the selection of mammalian cells for applications in regenerative medicine as well as cell-based functional assays or drug screening protocols. PMID:24558371

Amyloid-β peptide on sialyl-Lewis(X)-selectin-mediated membrane tether mechanics at the cerebral endothelial cell surface.

PubMed

Askarova, Sholpan; Sun, Zhe; Sun, Grace Y; Meininger, Gerald A; Lee, James C-M

2013-01-01

Increased deposition of amyloid-β peptide (Aβ) at the cerebral endothelial cell (CEC) surface has been implicated in enhancement of transmigration of monocytes across the brain blood barrier (BBB) in Alzheimer's disease (AD). In this study, quantitative immunofluorescence microscopy (QIM) and atomic force microscopy (AFM) with cantilevers biofunctionalized by sialyl-Lewis(x) (sLe(x)) were employed to investigate Aβ-altered mechanics of membrane tethers formed by bonding between sLe(x) and p-selectin at the CEC surface, the initial mechanical step governing the transmigration of monocytes. QIM results indicated the ability for Aβ to increase p-selectin expression at the cell surface and promote actin polymerization in both bEND3 cells (immortalized mouse CECs) and human primary CECs. AFM data also showed the ability for Aβ to increase cell stiffness and adhesion probability in bEND3 cells. On the contrary, Aβ lowered the overall force of membrane tether formation (Fmtf ), and produced a bimodal population of Fmtf , suggesting subcellular mechanical alterations in membrane tethering. The lower Fmtf population was similar to the results obtained from cells treated with an F-actin-disrupting drug, latrunculin A. Indeed, AFM results also showed that both Aβ and latrunculin A decreased membrane stiffness, suggesting a lower membrane-cytoskeleton adhesion, a factor resulting in lower Fmtf . In addition, these cerebral endothelial alterations induced by Aβ were abrogated by lovastatin, consistent with its anti-inflammatory effects. In sum, these results demonstrated the ability for Aβ to enhance p-selectin expression at the CEC surface and induce cytoskeleton reorganization, which in turn, resulted in changes in membrane-cytoskeleton adhesion and membrane tethering, mechanical factors important in transmigration of monocytes through the BBB.

Amyloid-β Peptide on Sialyl-LewisX-Selectin-Mediated Membrane Tether Mechanics at the Cerebral Endothelial Cell Surface

PubMed Central

Askarova, Sholpan; Sun, Zhe; Sun, Grace Y.; Meininger, Gerald A.; Lee, James C-M.

2013-01-01

Increased deposition of amyloid-β peptide (Aβ) at the cerebral endothelial cell (CEC) surface has been implicated in enhancement of transmigration of monocytes across the brain blood barrier (BBB) in Alzheimer's disease (AD). In this study, quantitative immunofluorescence microscopy (QIM) and atomic force microscopy (AFM) with cantilevers biofunctionalized by sialyl-Lewisx (sLex) were employed to investigate Aβ-altered mechanics of membrane tethers formed by bonding between sLex and p-selectin at the CEC surface, the initial mechanical step governing the transmigration of monocytes. QIM results indicated the ability for Aβ to increase p-selectin expression at the cell surface and promote actin polymerization in both bEND3 cells (immortalized mouse CECs) and human primary CECs. AFM data also showed the ability for Aβ to increase cell stiffness and adhesion probability in bEND3 cells. On the contrary, Aβ lowered the overall force of membrane tether formation (Fmtf), and produced a bimodal population of Fmtf, suggesting subcellular mechanical alterations in membrane tethering. The lower Fmtf population was similar to the results obtained from cells treated with an F-actin-disrupting drug, latrunculin A. Indeed, AFM results also showed that both Aβ and latrunculin A decreased membrane stiffness, suggesting a lower membrane-cytoskeleton adhesion, a factor resulting in lower Fmtf. In addition, these cerebral endothelial alterations induced by Aβ were abrogated by lovastatin, consistent with its anti-inflammatory effects. In sum, these results demonstrated the ability for Aβ to enhance p-selectin expression at the CEC surface and induce cytoskeleton reorganization, which in turn, resulted in changes in membrane-cytoskeleton adhesion and membrane tethering, mechanical factors important in transmigration of monocytes through the BBB. PMID:23593361

REEPs Are Membrane Shaping Adapter Proteins That Modulate Specific G Protein-Coupled Receptor Trafficking by Affecting ER Cargo Capacity

PubMed Central

Ho, Vincent K.; Angelotti, Timothy

2013-01-01

Receptor expression enhancing proteins (REEPs) were identified by their ability to enhance cell surface expression of a subset of G protein-coupled receptors (GPCRs), specifically GPCRs that have proven difficult to express in heterologous cell systems. Further analysis revealed that they belong to the Yip (Ypt-interacting protein) family and that some REEP subtypes affect ER structure. Yip family comparisons have established other potential roles for REEPs, including regulation of ER-Golgi transport and processing/neuronal localization of cargo proteins. However, these other potential REEP functions and the mechanism by which they selectively enhance GPCR cell surface expression have not been clarified. By utilizing several REEP family members (REEP1, REEP2, and REEP6) and model GPCRs (α2A and α2C adrenergic receptors), we examined REEP regulation of GPCR plasma membrane expression, intracellular processing, and trafficking. Using a combination of immunolocalization and biochemical methods, we demonstrated that this REEP subset is localized primarily to ER, but not plasma membranes. Single cell analysis demonstrated that these REEPs do not specifically enhance surface expression of all GPCRs, but affect ER cargo capacity of specific GPCRs and thus their surface expression. REEP co-expression with α2 adrenergic receptors (ARs) revealed that this REEP subset interacts with and alter glycosidic processing of α2C, but not α2A ARs, demonstrating selective interaction with cargo proteins. Specifically, these REEPs enhanced expression of and interacted with minimally/non-glycosylated forms of α2C ARs. Most importantly, expression of a mutant REEP1 allele (hereditary spastic paraplegia SPG31) lacking the carboxyl terminus led to loss of this interaction. Thus specific REEP isoforms have additional intracellular functions besides altering ER structure, such as enhancing ER cargo capacity, regulating ER-Golgi processing, and interacting with select cargo proteins. Therefore, some REEPs can be further described as ER membrane shaping adapter proteins. PMID:24098485

Hormonal Regulation of Dendritic Cell Differentiation in the Thymus.

PubMed

Shirshev, S V; Orlova, E G; Loginova, O A; Nekrasova, I V; Gorbunova, O L; Maslennikova, I L

2018-06-19

We studied the effect of hormones estriol, ghrelin, kisspeptin, and chorionic gonadotropin in concentrations corresponding to their content in the peripheral blood in each trimester of pregnancy on the expression of membrane molecules on myeloid and plasmacytoid dendritic cells of the thymus. It was found that thymic myeloid dendritic cells are sensitive to the action of estriol and kisspeptin. Estriol in a concentration of the first trimester of pregnancy reduces the number of myeloid dendritic cells expressing receptor for thymic stromal lymphopoietin (CD11c+TSLP-R + ) and inhibitory molecule B7-H3 (CD11c + CD276 + ). In contrast to estriol, kisspeptin regulates the processes of differentiation of thymic myeloid dendritic cells in concentrations typical of the second-third trimesters and reduced their total number (CD11c + ) and the number of cells expressing TSLP-R (CD11c + TSLP-R + ). Estriol and kisspeptin do not affect the total number of plasmacytoid dendritic cells (CD303 + ) and expression of TSLP-R and CD276 by these cells. Ghrelin and chorionic gonadotropin in the studied concentrations had no significant effect on the total number of thymic myeloid and plasmacytoid dendritic cells and on the expression of membrane molecules of TSLP-R and CD276.

Driving mechanisms of passive and active transport across cellular membranes as the mechanisms of cell metabolism and development as well as the mechanisms of cellular distance reactions on hormonal expression and the immune response.

PubMed

Ponisovskiy, M R

2011-01-01

The article presents mechanisms of cell metabolism, cell development, cell activity, and maintenance of cellular stability. The literature is reviewed from the point of view of these concepts. The balance between anabolic and catabolic processes induces chemical potentials in the extracellular and intracellular media. The chemical potentials of these media are defined as the driving forces of both passive and active transport of substances across cellular membranes. The driving forces of substance transport across cellular membranes as in cellular metabolism and in immune responses and hormonal expressions are considered in the biochemical and biophysical models, reflecting the mechanisms for maintenance of stability of the internal medium and internal energy of an organism. The interactions of passive transport and active transport of substances across cellular walls promote cell proliferation, as well as the mechanism of cellular capacitors, promoting remote reactions across distance for hormonal expression and immune responses. The offered concept of cellular capacitors has given the possibility to explain the mechanism of remote responses of cells to new situations, resulting in the appearance of additional agents. The biophysical model develops an explanation of some cellular functions: cellular membrane action have been identified with capacitor action, based on the similarity of the structures and as well as on similarity of biophysical properties of electric data that confirm the action of the compound-specific interactions of cells within an organism, promoting hormonal expressions and immune responses to stabilize the thermodynamic system of an organism. Comparison of a cellular membrane action to a capacitor has given the possibility for the explanations of exocytosis and endocytosis mechanisms, internalization of the receptor-ligand complex, selection as a receptor reaction to a ligand by immune responses or hormonal effects, reflecting cellular distance reactions on the hormonal expressions, immune responses, and specificity of the mechanisms of immune reactions. Reviewing current research of cell activity, explanations are presented of mechanisms of apoptosis, autophagy, hormonal expression, and immune responses from the point of view of described cellular mechanisms. Thermodynamic laws are used to confirm the importance of the actions of these mechanisms for maintenance of stability of the internal medium and internal energy of an organism.

Association of Shiga toxin glycosphingolipid receptors with membrane microdomains of toxin-sensitive lymphoid and myeloid cells.

PubMed

Kouzel, Ivan U; Pohlentz, Gottfried; Storck, Wiebke; Radamm, Lena; Hoffmann, Petra; Bielaszewska, Martina; Bauwens, Andreas; Cichon, Christoph; Schmidt, M Alexander; Mormann, Michael; Karch, Helge; Müthing, Johannes

2013-03-01

Glycosphingolipids (GSLs) of the globo-series constitute specific receptors for Shiga toxins (Stxs) released by certain types of pathogenic Escherichia coli strains. Stx-loaded leukocytes may act as transporter cells in the blood and transfer the toxin to endothelial target cells. Therefore, we performed a thorough investigation on the expression of globo-series GSLs in serum-free cultivated Raji and Jurkat cells, representing B- and T-lymphocyte descendants, respectively, as well as THP-1 and HL-60 cells of the monocyte and granulocyte lineage, respectively. The presence of Stx-receptors in GSL preparations of Raji and THP-1 cells and the absence in Jurkat and HL-60 cells revealed high compliance of solid-phase immunodetection assays with the expression profiles of receptor-related glycosyltransferases, performed by qRT-PCR analysis, and Stx2-caused cellular damage. Canonical microdomain association of Stx GSL receptors, sphingomyelin, and cholesterol in membranes of Raji and THP-1 cells was assessed by comparative analysis of detergent-resistant membrane (DRM) and nonDRM fractions obtained by density gradient centrifugation and showed high correlation based on nonparametric statistical analysis. Our comprehensive study on the expression of Stx-receptors and their subcellular distribution provides the basis for exploring the functional role of lipid raft-associated Stx-receptors in cells of leukocyte origin.

Oligolysine-based saccharide clusters: synthesis and specificity.

PubMed Central

Frison, Natacha; Marceau, Philippe; Roche, Annie-Claude; Monsigny, Michel; Mayer, Roger

2002-01-01

In search of specific and highly selective sugar clusters for cell receptors, such as membrane lectins, various disaccharides were coupled to small peptide cores through an amide bond. In a first step, the reducing disaccharides, i.e. lactose and three different dimannoses, were converted into glycosyl-pyroglutamyl-beta-alanine derivatives. The free carboxylic group of these conjugates was then coupled to the alpha and epsilon amino groups of the core peptide (Lys( n )-Ala-Cys-NH2) with n =1 to 5, with complete substitution leading to homogeneous glycoclusters. The thiol group of the cysteine residue was used to tag the glycosylated oligolysines upon reaction with fluorescein iodoacetamide. The affinity of these glycoclusters towards two plant lectins was assessed by surface plasmon resonance. The selectivity of their cell uptake was investigated by flow cytometry using two types of cells: a human hepatoma cell line (HepG2 cells) expressing the plasma membrane galactose-specific lectin, and monocyte-derived dendritic cells expressing the plasma membrane mannose-specific lectin. The glycoclusters containing four or five disaccharides were shown to bind plant lectins and cell surface membrane lectins with a narrow selectivity and with a high affinity. PMID:12119048

[The Role of Membrane-Bound Heat Shock Proteins Hsp90 in Migration of Tumor Cells in vitro and Involvement of Cell Surface Heparan Sulfate Proteoglycans in Protein Binding to Plasma Membrane].

PubMed

Snigireva, A V; Vrublevskaya, V V; Skarga, Y Y; Morenkov, O S

2016-01-01

Heat shock protein Hsp90, detected in the extracellular space and on the membrane of cells, plays an important role in cell motility, migration, invasion and metastasis of tumor cells. At present, the functional role and molecular mechanisms of Hsp90 binding to plasma membrane are not elucidated. Using isoform-specific antibodies against Hsp90, Hsp9α and Hsp90β, we showed that membrane-bound Hsp90α and Hsp90β play a significant role in migration of human fibrosarcoma (HT1080) and glioblastoma (A-172) cells in vitro. Disorders of sulfonation of cell heparan sulfates, cleavage of cell heparan. sulfates by heparinase I/III as well as treatment of cells with heparin lead to an abrupt reduction in the expression level of Hsp90 isoforms. Furthermore, heparin significantly inhibits tumor cell migration. The results obtained demonstrate that two isoforms of membrane-bound Hsp90 are involved in migration of tumor cells in vitro and that cell surface heparan sulfate proteoglycans play a pivotal role in the "anchoring" of Hsp90α and Hsp90β to the plasma membrane.

cGAS-Mediated Innate Immunity Spreads Intercellularly through HIV-1 Env-Induced Membrane Fusion Sites.

PubMed

Xu, Shuting; Ducroux, Aurélie; Ponnurangam, Aparna; Vieyres, Gabrielle; Franz, Sergej; Müsken, Mathias; Zillinger, Thomas; Malassa, Angelina; Ewald, Ellen; Hornung, Veit; Barchet, Winfried; Häussler, Susanne; Pietschmann, Thomas; Goffinet, Christine

2016-10-12

Upon sensing cytoplasmic retroviral DNA in infected cells, cyclic GMP-AMP (cGAMP) synthase (cGAS) produces the cyclic dinucleotide cGAMP, which activates STING to trigger a type I interferon (IFN) response. We find that membrane fusion-inducing contact between donor cells expressing the HIV envelope (Env) and primary macrophages endogenously expressing the HIV receptor CD4 and coreceptor enable intercellular transfer of cGAMP. This cGAMP exchange results in STING-dependent antiviral IFN responses in target macrophages and protection from HIV infection. Furthermore, under conditions allowing cell-to-cell transmission of HIV-1, infected primary T cells, but not cell-free virions, deliver cGAMP to autologous macrophages through HIV-1 Env and CD4/coreceptor-mediated membrane fusion sites and induce a STING-dependent, but cGAS-independent, IFN response in target cells. Collectively, these findings identify an infection-specific mode of horizontal transfer of cGAMP between primary immune cells that may boost antiviral responses, particularly in infected tissues in which cell-to-cell transmission of virions exceeds cell-free infection. Copyright © 2016 Elsevier Inc. All rights reserved.

Regulation of protein expression and function of octn2 in forskolin-induced syncytialization in BeWo Cells.

PubMed

Huang, F-D; Kung, F-L; Tseng, Y-C; Chen, M-R; Chan, H-S; Lin, C-J

2009-02-01

Placental OCTN2 is a high-affinity carnitine transporter that can interact with a number of therapeutic agents. The process of syncytialization is associated with the expression of a variety of genes. However, the association between syncytialization and OCTN2 expression is not yet clear. Given that forskolin induces BeWo cells to undergo biochemical and morphological differentiation, the purpose of the present study was to investigate whether the function and expression of OCTN2 are influenced by forskolin treatment during syncytialization. The forskolin-induced differentiation of BeWo cells was validated by secretion of beta-human chorionic gonadotropin (beta-hCG) and syncytin expression. Cellular localization of OCTN2 was analyzed by confocal microscopy. Expression of OCTN2 and the modular proteins PDZK1, PDZK2, NHERF1 and NHERF2 was analyzed by Western blotting and carnitine uptake by BeWo cells was estimated and the kinetic properties of uptake measured. The results showed that forskolin treatment increased beta-hCG secretion and syncytin expression, suggesting induction of syncytialization. Confocal images of BeWo cells showed the localization of OCTN2 in the brush-border membrane. OCTN2 protein expression was upregulated in isolated brush-border membranes by long-term forskolin treatment, but the V(m) for carnitine uptake was unchanged, although the K(m) increased. PDZK1, NHERF1 and NHERF2 protein expression in the brush-border membrane was downregulated by forskolin treatment, whereas PDZK2 levels remained unchanged. In conclusion, protein expression and function of OCTN2 in BeWo cells can be regulated by forskolin treatment. While the presence of forskolin results in an increase in OCTN2 protein expression, the increase in uptake capacity may be compensated by the decreased expression of PDZK1, NHERF1 or NHERF2.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Atsushi; Graduate School of Science and Engineering, Saitama University, Saitama 338-8570; Green Tea Laboratory, Saitama Prefectural Agriculture and Forestry Research Center, Saitama 358-0042

Highlights: •EGCG reduced cell motility of highly metastatic human lung cancer cells. •EGCG increased cell stiffness of the cells, indicating the inhibition of phenotypes of EMT. •EGCG inhibited expression of vimentin and Slug in the cells at the leading edge of scratch. •Treatment of MβCD increased cell stiffness, and inhibited cell motility and vimentin expression. •Inhibition of EMT phenotypes with EGCG is a mechanism-based inhibition of cancer metastasis. -- Abstract: Cell motility and cell stiffness are closely related to metastatic activity of cancer cells. (−)-Epigallocatechin gallate (EGCG) has been shown to inhibit spontaneous metastasis of melanoma cell line into themore » lungs of mice, so we studied the effects of EGCG on cell motility, cell stiffness, and expression of vimentin and Slug, which are molecular phenotypes of epithelial–mesenchymal transition (EMT). Treatments of human non-small cell lung cancer cell lines H1299 and Lu99 with 50 and 100 μM EGCG reduced cell motility to 67.5% and 43.7% in H1299, and 71.7% and 31.5% in Lu99, respectively in in vitro wound healing assay. Studies on cell stiffness using atomic force microscope (AFM) revealed that treatment with 50 μM EGCG increased Young’s modulus of H1299 from 1.24 to 2.25 kPa and that of Lu99 from 1.29 to 2.28 kPa, showing a 2-fold increase in cell stiffness, i.e. rigid elasticity of cell membrane. Furthermore, treatment with 50 μM EGCG inhibited high expression of vimentin and Slug in the cells at a leading edge of scratch. Methyl-β-cyclodextrin, a reagent to deplete cholesterol in plasma membrane, showed inhibition of EMT phenotypes similar that by EGCG, suggesting that EGCG induces inhibition of EMT phenotypes by alteration of membrane organization.« less

A Novel Function for the nm23-Hl Gene: Overexpression in Human Breast Carcinoma Cells Leads to the Formation of Basement Membrane and Growth Arrest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howlett, Anthony R; Petersen, Ole W; Steeg, Patricia S

1994-01-01

We have developed a culture system using reconstituted basement membrane components in which normal human mammary epithelial cells exhibit several aspects of the development and differentiation process, including formation of acinar-like structures, production and basal deposition of basement membrane components, and production and apical secretion of sialomucins. Cell lines and cultures from human breast carcinomas failed to recapitulate this process. The data indicate the importance of cellular interactions with the basement membrane in the regulation of normal breast differentiation and, potentially, its loss in neoplasia. Our purpose was to use this assay to investigate the role of the putative metastasismore » suppressor gene nm23-H1 in mammary development and differentiation. The metastatic human breast carcinoma cell line MDA-MB-435, clones transfected with a control pCMVBamneo vector, and clones transfected with pCMVBamneo vector containing nm23-H1 complementary DNA (the latter of which exhibited a substantial reduction in spontaneous metastatic potential in vivo) were cultured within a reconstituted basement membrane. Clones were examined for formation of acinus-like spheres, deposition of basement membrane components, production of sialomucin, polarization, and growth arrest. In contrast to the parental cell line and control transfectants, MDA-MB-435 breast carcinoma cells overexpressing Nm23-H1 protein regained several aspects of the normal phenotype within reconstituted basement membrane. Nm23-H1 protein-positive cells formed organized acinus-like spheres, deposited the basement membrane components type IV collagen and, to some extent, laminin to the outside of the spheres, expressed sialomucin, and growth arrested. Growth arrest of Nm23-H1 protein-positive cells was preceded by and correlated with formation of a basement membrane, suggesting a causal relationship. The data indicate a previously unidentified cause-and-effect relationship between nm23-H1 gene expression and morphological-biosynthetic-growth aspects of breast differentiation in this model system. While the basement membrane microenvironment is capable of directing the differentiation of normal human breast cells, neoplastic transformation abrogates this relationship, suggesting that intrinsic cellular events are also critical to this process. The data identify nm23-H1 gene expression as one of these events, suggesting an important role in the modulation of cellular responsiveness to the microenvironment. The data also identify previously unknown growth inhibitory effects of nm23-H1 gene overexpression.« less

Quaternary structure and apical membrane sorting of the mammalian NaSi-1 sulfate transporter in renal cell lines.

PubMed

Regeer, Ralf R; Nicke, Annette; Markovich, Daniel

2007-01-01

NaSi-1 encodes a Na(+)-sulfate cotransporter expressed on the apical membrane of renal proximal tubular cells, which is responsible for body sulfate homeostasis. Limited information is available on NaSi-1 protein structure and the mechanisms controlling its apical membrane sorting. The aims of this study were to biochemically determine the quaternary structure of the rat NaSi-1 protein and to characterize its expression in renal epithelial cell lines. Hexahistidyl-tagged NaSi-1 (NaSi-1-His) proteins expressed in Xenopus oocytes, appeared as two bands of about 60 and 75 kDa. PNGase F treatment shifted both bands to 57 kDa while endoglycosidase H treatment led to a downward shift of the lower molecular mass band only. Mutagenesis of a putative N-glycosylation site (N591S) produced a single band that was not shifted by endoglycosidase H or PNGase F, confirming a single glycosylation site at residue 591. Blue native-PAGE and cross-linking experiments revealed dimeric complexes, suggesting the native form of NaSi-1 to be a dimer. Transient transfection of EGFP/NaSi-1 in renal epithelial cells (OK, LLC-PK1 and MDCK) demonstrated apical membrane sorting, which was insensitive to tunicamycin. Transfection of the EGFP/NaSi-1 N591S glycosylation mutant also showed apical expression, suggesting N591 is not essential for apical sorting. Treatment with cholesterol depleting compounds did not disrupt apical sorting, but brefeldin A led to misrouting to the basolateral membrane, suggesting that NaSi-1 sorting is through the ER to Golgi pathway. Our data demonstrates that NaSi-1 forms a dimeric protein which is glycosylated at N591, whose sorting to the apical membrane in renal epithelial cells is brefeldin A-sensitive and independent of lipid rafts or glycosylation.

Analysis of molecular assemblies by flow cytometry: determinants of Gi1 and by binding

NASA Astrophysics Data System (ADS)

Sarvazyan, Noune A.; Neubig, Richard R.

1998-05-01

We report here a novel application of flow cytometry for the quantitative analysis of the high affinity interaction between membrane proteins both in detergent solutions and when reconstituted into lipid vesicles. The approach is further advanced to permit the analysis of binding to expressed protein complexes in native cell membranes. The G protein heterotrimer signal transduction function links the extracellularly activated transmembrane receptors and intracellular effectors. Upon activation, (alpha) and (beta) (gamma) subunits of G protein undergo a dissociation/association cycle on the cell membrane interface. The binding parameters of solubilized G protein (alpha) and (beta) (gamma) subunits have been defined but little is known quantitatively about their interactions in the membrane. Using a novel flow cytometry approach, the binding of low nanomolar concentrations of fluorescein-labeled G(alpha) i1 (F- (alpha) ) to (beta) (gamma) both in detergent solution and in a lipid environment was quantitatively compared. Unlabeled (beta) $gama reconstituted in biotinylated phospholipid vesicles bound F-(alpha) tightly (Kd 6 - 12 nM) while the affinity for biotinylated-(beta) (gamma) in Lubrol was even higher (Kd of 2.9 nM). The application of this approach to proteins expressed in native cell membranes will advance our understanding of G protein function in context of receptor and effector interaction. More generally, this approach can be applied to study the interaction of any fluorescently labeled protein with a membrane protein which can be expressed in Sf9 plasma membranes.

Actin-Binding Protein Requirement for Cortical Stability and Efficient Locomotion

NASA Astrophysics Data System (ADS)

Cunningham, C. Casey; Gorlin, Jed B.; Kwiatkowski, David J.; Hartwig, John H.; Janmey, Paul A.; Randolph Byers, H.; Stossel, Thomas P.

1992-01-01

Three unrelated tumor cell lines derived from human malignant melanomas lack actin-binding protein (ABP), which cross-links actin filaments in vitro and connects these filaments to plasma membrane glycoproteins. The ABP-deficient cells have impaired locomotion and display circumferential blebbing of the plasma membrane. Expression of ABP in one of the lines after transfection restored translocational motility and reduced membrane blebbing. These findings establish that ABP functions to stabilize cortical actin in vivo and is required for efficient cell locomotion.

Organization of K88ac-encoded polypeptides in the Escherichia coli cell envelope: use of minicells and outer membrane protein mutants for studying assembly of pili.

PubMed

Dougan, G; Dowd, G; Kehoe, M

1983-01-01

Escherichia coli K-12 minicells, harboring recombinant plasmids encoding polypeptides involved in the expression of K88ac adhesion pili on the bacterial cell surface, were labeled with [35S]methionine and fractionated by a variety of techniques. A 70,000-dalton polypeptide, the product of the K88ac adhesion cistron adhA, was primarily located in the outer membrane of minicells, although it was less clearly associated with this membrane than the classical outer membrane proteins OmpA and matrix protein. Two polypeptides of molecular weights 26,000 and 17,000 (the products of adhB and adhC, respectively) were located in significant amounts in the periplasmic space. The 29,000-dalton polypeptide was shown to be processed in E. coli minicells. The 23.500-dalton K88ac pilus subunit (the product of adhD) was detected in both inner and outer membrane fractions. E. coli mutants defective in the synthesis of murein lipoprotein or the major outer membrane polypeptide OmpA were found to express normal amounts of K88ac antigen on the cell surface, whereas expression of the K88ac antigen was greatly reduced in perA mutants. The possible functions of the adh cistron products are discussed.

Bioimaging of Fluorescence-Labeled Mitochondria in Subcutaneously Grafted Murine Melanoma Cells by the “In Vivo Cryotechnique”

PubMed Central

Lei, Ting; Huang, Zheng; Ohno, Nobuhiko; Wu, Bao; Sakoh, Takashi; Saitoh, Yurika; Saiki, Ikuo

2014-01-01

The microenvironments of organs with blood flow affect the metabolic profiles of cancer cells, which are influenced by mitochondrial functions. However, histopathological analyses of these aspects have been hampered by technical artifacts of conventional fixation and dehydration, including ischemia/anoxia. The purpose of this study was to combine the in vivo cryotechnique (IVCT) with fluorescent protein expression, and examine fluorescently labeled mitochondria in grafted melanoma tumors. The intensity of fluorescent proteins was maintained well in cultured B16-BL6 cells after cryotechniques followed by freeze-substitution (FS). In the subcutaneous tumors of mitochondria-targeted DsRed2 (mitoDsRed)-expressing cells, a higher number of cancer cells were found surrounding the widely opened blood vessels that contained numerous erythrocytes. Such blood vessels were immunostained positively for immunoglobulin M and ensheathed by basement membranes. MitoDsRed fluorescence was detected in scattering melanoma cells using the IVCT-FS method, and the total mitoDsRed volume in individual cancer cells was significantly decreased with the expression of markers of hypoxia. MitoDsRed was frequently distributed throughout the cytoplasm and in processes extending along basement membranes. IVCT combined with fluorescent protein expression is a useful tool to examine the behavior of fluorescently labeled cells and organelles. We propose that the mitochondrial volume is dynamically regulated in the hypoxic microenvironment and that mitochondrial distribution is modulated by cancer cell interactions with basement membranes. PMID:24394469

Stable Expression of the Motor Protein Prestin in Chinese Hamster Ovary Cells

NASA Astrophysics Data System (ADS)

Iida, Koji; Konno, Kazuaki; Oshima, Takeshi; Tsumoto, Kouhei; Ikeda, Katsuhisa; Kumagai, Izumi; Kobayashi, Toshimitsu; Wada, Hiroshi

Mammalian hearing sensitivity relies on a mechanical amplification mechanism involving the outer hair cells (OHCs), which rapidly alter their longitudinal length in response to changes in their membrane potential. The molecular basis of this mechanism is thought to be a motor protein embedded in the lateral membrane of the OHCs. Recently, this motor protein was identified and termed prestin. Since then, prestin has been researched intensively to elucidate the behavior of the OHCs. However, little progress in the study of prestin at the molecular level has been made because no method of obtaining an adequate amount of prestin has been established. In this study, therefore, an attempt was made to construct a stable expression system of prestin using Chinese hamster ovary (CHO) cells. The expression of prestin in the transfected CHO cells and the activity of prestin on CHO cells were confirmed by immunofluorescence and whole-cell patch-clamp measurements, respectively.

Nuclear envelope and genome interactions in cell fate

PubMed Central

Talamas, Jessica A.; Capelson, Maya

2015-01-01

The eukaryotic cell nucleus houses an organism’s genome and is the location within the cell where all signaling induced and development-driven gene expression programs are ultimately specified. The genome is enclosed and separated from the cytoplasm by the nuclear envelope (NE), a double-lipid membrane bilayer, which contains a large variety of trans-membrane and associated protein complexes. In recent years, research regarding multiple aspects of the cell nucleus points to a highly dynamic and coordinated concert of efforts between chromatin and the NE in regulation of gene expression. Details of how this concert is orchestrated and how it directs cell differentiation and disease are coming to light at a rapid pace. Here we review existing and emerging concepts of how interactions between the genome and the NE may contribute to tissue specific gene expression programs to determine cell fate. PMID:25852741

Adenoviral vector gene delivery via the round window membrane in guinea pigs.

PubMed

Suzuki, Mitsuya; Yamasoba, Tatsuya; Suzukawa, Keigo; Kaga, Kimitaka

2003-10-27

We have found that damage from a local anesthetic solution containing phenol permitted beta-galactosidase (beta-gal) gene delivery to the guinea pig inner ear via the round window membrane (RWM). RWM damage was evident as degeneration of the outer epithelium. After adenovirus lacZ vector was applied to the damaged RWM, immunohistochemistry showed strong beta-gal expression in the RWM, mesothelial cells, organ of Corti, spiral limbus, spiral ligament and spiral ganglion. In the vestibular labyrinth, expression was seen in the sensory and supporting cells, transitional cells, and the dark-cell area. Thus, adenovirus can transfect a variety of inner ear cells in the guinea pig through a damaged RWM.

Dual Role of Jun N-Terminal Kinase Activity in Bone Morphogenetic Protein-Mediated Drosophila Ventral Head Development.

PubMed

Park, Sung Yeon; Stultz, Brian G; Hursh, Deborah A

2015-12-01

The Drosophila bone morphogenetic protein encoded by decapentaplegic (dpp) controls ventral head morphogenesis by expression in the head primordia, eye-antennal imaginal discs. These are epithelial sacs made of two layers: columnar disc proper cells and squamous cells of the peripodial epithelium. dpp expression related to head formation occurs in the peripodial epithelium; cis-regulatory mutations disrupting this expression display defects in sensory vibrissae, rostral membrane, gena, and maxillary palps. Here we document that disruption of this dpp expression causes apoptosis in peripodial cells and underlying disc proper cells. We further show that peripodial Dpp acts directly on the disc proper, indicating that Dpp must cross the disc lumen to act. We demonstrate that palp defects are mechanistically separable from the other mutant phenotypes; both are affected by the c-Jun N-terminal kinase pathway but in opposite ways. Slight reduction of both Jun N-terminal kinase and Dpp activity in peripodial cells causes stronger vibrissae, rostral membrane, and gena defects than Dpp alone; additionally, strong reduction of Jun N-terminal kinase activity alone causes identical defects. A more severe reduction of dpp results in similar vibrissae, rostral membrane, and gena defects, but also causes mutant maxillary palps. This latter defect is correlated with increased peripodial Jun N-terminal kinase activity and can be caused solely by ectopic activation of Jun N-terminal kinase. We conclude that formation of sensory vibrissae, rostral membrane, and gena tissue in head morphogenesis requires the action of Jun N-terminal kinase in peripodial cells, while excessive Jun N-terminal kinase signaling in these same cells inhibits the formation of maxillary palps. Copyright © 2015 by the Genetics Society of America.

Development of bioluminescent chick chorioallantoic membrane (CAM) models for primary pancreatic cancer cells: a platform for drug testing

PubMed Central

Rovithi, Maria; Avan, Amir; Funel, Niccola; Leon, Leticia G.; Gomez, Valentina E.; Wurdinger, Thomas; Griffioen, Arjan W.; Verheul, Henk M. W.; Giovannetti, Elisa

2017-01-01

The aim of the present study was to develop chick-embryo chorioallantoic membrane (CAM) bioluminescent tumor models employing low passage cell cultures obtained from primary pancreatic ductal adenocarcinoma (PDAC) cells. Primary PDAC cells transduced with lentivirus expressing Firefly-luciferase (Fluc) were established and inoculated onto the CAM membrane, with >80% engraftment. Fluc signal reliably correlated with tumor growth. Tumor features were evaluated by immunohistochemistry and genetic analyses, including analysis of mutations and mRNA expression of PDAC pivotal genes, as well as microRNA (miRNA) profiling. These studies showed that CAM tumors had histopathological and genetic characteristic comparable to the original tumors. We subsequently tested the modulation of key miRNAs and the activity of gemcitabine and crizotinib on CAM tumors, showing that combination treatment resulted in 63% inhibition of tumor growth as compared to control (p < 0.01). These results were associated with reduced expression of miR-21 and increased expression of miR-155. Our study provides the first evidence that transduced primary PDAC cells can form tumors on the CAM, retaining several histopathological and (epi)genetic characteristics of original tumors. Moreover, our results support the use of these models for drug testing, providing insights on molecular mechanisms underlying antitumor activity of new drugs/combinations. PMID:28304379

Coupled Segmentation of Nuclear and Membrane-bound Macromolecules through Voting and Multiphase Level Set

PubMed Central

Wen, Quan

2014-01-01

Membrane-bound macromolecules play an important role in tissue architecture and cell-cell communication, and is regulated by almost one-third of the genome. At the optical scale, one group of membrane proteins expresses themselves as linear structures along the cell surface boundaries, while others are sequestered; and this paper targets the former group. Segmentation of these membrane proteins on a cell-by-cell basis enables the quantitative assessment of localization for comparative analysis. However, such membrane proteins typically lack continuity, and their intensity distributions are often very heterogeneous; moreover, nuclei can form large clump, which further impedes the quantification of membrane signals on a cell-by-cell basis. To tackle these problems, we introduce a three-step process to (i) regularize the membrane signal through iterative tangential voting, (ii) constrain the location of surface proteins by nuclear features, where clumps of nuclei are segmented through a delaunay triangulation approach, and (iii) assign membrane-bound macromolecules to individual cells through an application of multi-phase geodesic level-set. We have validated our method using both synthetic data and a dataset of 200 images, and are able to demonstrate the efficacy of our approach with superior performance. PMID:25530633

Developmental Regulation of a Plasma Membrane Arabinogalactan Protein Epitope in Oilseed Rape Flowers.

PubMed Central

Pennell, RI; Janniche, L; Kjellbom, P; Scofield, GN; Peart, JM; Roberts, K

1991-01-01

We have identified and characterized the temporal and spatial regulation of a plasma membrane arabinogalactan protein epitope during development of the aerial parts of oilseed rape using the monoclonal antibody JIM8. The JIM8 epitope is expressed by the first cells of the embryo and by certain cells in the sexual organs of flowers. During embryogenesis, the JIM8 epitope ceases to be expressed by the embryo proper but is still found in the suspensor. During differentiation of the stamens and carpels, expression of the JIM8 epitope progresses from one cell type to another, ultimately specifying the endothecium and sperm cells, the nucellar epidermis, synergid cells, and the egg cell. This complex temporal sequence demonstrates rapid turnover of the JIM8 epitope. There is no direct evidence for any cell-inductive process in plant development. However, if cell-cell interactions exist in plants and participate in flower development, the JIM8 epitope may be a marker for one set of them. PMID:12324592

KCNQ and KCNE Potassium Channel Subunit Expression in Bovine Retinal Pigment Epithelium

PubMed Central

Zhang, Xiaoming; Hughes, Bret A.

2013-01-01

Human, monkey, and bovine retinal pigment epithelial (RPE) cells exhibit an M-type K+ current, which in many other cell types is mediated by channels composed of KCNQ α-subunits and KCNE auxiliary subunits. Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 in the monkey RPE. Here, we investigated the expression of KCNQ and KCNE subunits in native bovine RPE. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE, but, in Western blot analysis of RPE plasma membranes, only KCNQ5 was detected. Among the five members of the KCNE gene family, transcripts for KCNE1, KCNE2, KCNE3, and KCNE4 were detected in bovine RPE, but only KCNE1 and KCNE2 proteins were detected. Immunohistochemistry of frozen bovine retinal sections revealed KCNE1 expression near the apical and basal membranes of the RPE, in cone outer segments, in the outer nuclear layer, and throughout the inner retina. The localization of KCNE1 in the RPE basal membrane, where KCNQ5 was previously found to be present, suggests that this β-subunit may contribute to M-type K+ channels in this membrane. PMID:24416770

Investigation of free fatty acid associated recombinant membrane receptor protein expression in HEK293 cells using Raman spectroscopy, calcium imaging, and atomic force microscopy.

PubMed

Lin, Juqiang; Xu, Han; Wu, Yangzhe; Tang, Mingjie; McEwen, Gerald D; Liu, Pin; Hansen, Dane R; Gilbertson, Timothy A; Zhou, Anhong

2013-02-05

G-protein-coupled receptor 120 (GPR120) is a previously orphaned G-protein-coupled receptor that apparently functions as a sensor for dietary fat in the gustatory and digestive systems. In this study, a cDNA sequence encoding a doxycycline (Dox)-inducible mature peptide of GPR120 was inserted into an expression vector and transfected in HEK293 cells. We measured Raman spectra of single HEK293 cells as well as GPR120-expressing HEK293-GPR120 cells at a 48 h period following the additions of Dox at several concentrations. We found that the spectral intensity of HEK293-GPR120 cells is dependent upon the dose of Dox, which correlates with the accumulation of GPR120 protein in the cells. However, the amount of the fatty acid activated changes in intracellular calcium (Ca(2+)) as measured by ratiometric calcium imaging was not correlated with Dox concentration. Principal components analysis (PCA) of Raman spectra reveals that the spectra from different treatments of HEK293-GPR120 cells form distinct, completely separated clusters with the receiver operating characteristic (ROC) area of 1, while those spectra for the HEK293 cells form small overlap clusters with the ROC area of 0.836. It was also found that expression of GPR120 altered the physiochemical and biomechanical properties of the parental cell membrane surface, which was quantitated by atomic force microscopy (AFM). These findings demonstrate that the combination of Raman spectroscopy, calcium imaging, and AFM may provide new tools in noninvasive and quantitative monitoring of membrane receptor expression induced alterations in the biophysical and signaling properties of single living cells.

Subcellular localization and distribution of the reduced folate carrier in normal rat tissues.

PubMed

Hinken, M; Halwachs, S; Kneuer, C; Honscha, W

2011-01-27

The reduced folate carrier (Rfc1; Slc19a1) mediated transport of reduced folates and antifolate drugs such as methotrexate (MTX) play an essential role in physiological folate homeostasis and MTX cancer chemotherapy. As no systematic reports are as yet available correlating Rfc1 gene expression and protein levels in all tissues crucial for folate and antifolate uptake, storage or elimination, we investigated gene and protein expression of rat Rfc1 (rRfc1) in selected tissues. This included the generation of a specific anti-rRfc1 antibody. Rabbits were immunised with isolated rRfc1 peptides producing specific anti-rRfc1 antiserum targeted to the intracellular C-terminus of the carrier. Using RT-PCR analysis, high rRfc1 transcript levels were detected in colon, kidney, brain, thymus, and spleen. Moderate rRfc1 gene expression was observed in small intestine, liver, bone marrow, lung, and testes whereas transcript levels were negligible in heart, skeletal muscle or leukocytes. Immunohistochemical analyses revealed strong carrier expression in the apical membrane of tunica mucosa epithelial cells of small intestine and colon, in the brush-border membrane of choroid plexus epithelial cells or in endothelial cells of small vessels in brain and heart. Additionally, high rRfc1 protein levels were localized in the basolateral membrane of renal tubular epithelial cells, in the plasma membrane of periportal hepatocytes, and sertoli cells of the testes. Taken together, our results demonstrated that rRfc1 is expressed almost ubiquitously but to very different levels. The predominant tissue distribution supports the essential role of Rfc1 in physiological folate homeostasis. Moreover, our results may contribute to understand antifolate pharmacokinetics and selected organ toxicity associated with MTX chemotherapy.

Effect of pro-inflammatory mediators on membrane-associated mucins expressed by human ocular surface epithelial cells.

PubMed

Albertsmeyer, Ann-Christin; Kakkassery, Vinodh; Spurr-Michaud, Sandra; Beeks, Olivia; Gipson, Ilene K

2010-03-01

Membrane-associated mucins are altered on the ocular surface in non-Sjögren's dry eye. This study sought to determine if inflammatory mediators, present in tears of dry eye patients, regulate membrane-associated mucins MUC1 and -16 at the level of gene expression, protein biosynthesis and/or ectodomain release. A human corneal limbal epithelial cell line (HCLE), which produces membrane-associated mucins, was used. Cells were treated with interleukin (IL)-6, -8, or -17, tumor necrosis factor-alpha (TNF-alpha), and Interferon-gamma (IFN-gamma), or a combination of TNF-alpha and IFN-gamma, or IFN-gamma and IL-17, for 1, 6, 24, or 48 h. Presence of receptors for these mediators was verified by RT-PCR. Effects of the cytokines on expression levels of MUC1 and -16 were determined by real-time PCR, and on mucin protein biosynthesis and ectodomain release in cell lysates and culture media, respectively, by immunoblot analysis. TNF-alpha and IFN-gamma each significantly induced MUC1 expression, cellular protein content and ectodomain release over time. Combined treatment with the two cytokines was not additive. By comparison, one of the inflammatory mediators, IFN-gamma, affected all three parameters-gene expression, cellular protein, and ectodomain release-for MUC16. Combined treatment with TNF-alpha and IFN-gamma showed effects similar to IFN-gamma alone, except that ectodomain release followed that of TNF-alpha, which induced MUC16 ectodomain release. In conclusion, inflammatory mediators present in tears of dry eye patients can affect MUC1 and -16 on corneal epithelial cells and may be responsible for alterations of surface mucins in dry eye.

Endocytosis and membrane receptor internalization: implication of F-BAR protein Carom.

PubMed

Xu, Yanjie; Xia, Jixiang; Liu, Suxuan; Stein, Sam; Ramon, Cueto; Xi, Hang; Wang, Luqiao; Xiong, Xinyu; Zhang, Lixiao; He, Dingwen; Yang, William; Zhao, Xianxian; Cheng, Xiaoshu; Yang, Xiaofeng; Wang, Hong

2017-03-01

Endocytosis is a cellular process mostly responsible for membrane receptor internalization. Cell membrane receptors bind to their ligands and form a complex which can be internalized. We previously proposed that F-BAR protein initiates membrane curvature and mediates endocytosis via its binding partners. However, F-BAR protein partners involved in membrane receptor endocytosis and the regulatory mechanism remain unknown. In this study, we established database mining strategies to explore mechanisms underlying receptor-related endocytosis. We identified 34 endocytic membrane receptors and 10 regulating proteins in clathrin-dependent endocytosis (CDE), a major process of membrane receptor internalization. We found that F-BAR protein FCHSD2 (Carom) may facilitate endocytosis via 9 endocytic partners. Carom is highly expressed, along with highly expressed endocytic membrane receptors and partners, in endothelial cells and macrophages. We established 3 models of Carom-receptor complexes and their intracellular trafficking based on protein interaction and subcellular localization. We conclude that Carom may mediate receptor endocytosis and transport endocytic receptors to the cytoplasm for receptor signaling and lysosome/proteasome degradation, or to the nucleus for RNA processing, gene transcription and DNA repair.

Membrane protein synthesis in cell-free systems: from bio-mimetic systems to bio-membranes.

PubMed

Sachse, Rita; Dondapati, Srujan K; Fenz, Susanne F; Schmidt, Thomas; Kubick, Stefan

2014-08-25

When taking up the gauntlet of studying membrane protein functionality, scientists are provided with a plethora of advantages, which can be exploited for the synthesis of these difficult-to-express proteins by utilizing cell-free protein synthesis systems. Due to their hydrophobicity, membrane proteins have exceptional demands regarding their environment to ensure correct functionality. Thus, the challenge is to find the appropriate hydrophobic support that facilitates proper membrane protein folding. So far, various modes of membrane protein synthesis have been presented. Here, we summarize current state-of-the-art methodologies of membrane protein synthesis in biomimetic-supported systems. The correct folding and functionality of membrane proteins depend in many cases on their integration into a lipid bilayer and subsequent posttranslational modification. We highlight cell-free systems utilizing the advantages of biological membranes. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Functional and Evolutionary Analysis of the CASPARIAN STRIP MEMBRANE DOMAIN PROTEIN Family1[C][W

PubMed Central

Roppolo, Daniele; Boeckmann, Brigitte; Pfister, Alexandre; Boutet, Emmanuel; Rubio, Maria C.; Dénervaud-Tendon, Valérie; Vermeer, Joop E.M.; Gheyselinck, Jacqueline; Xenarios, Ioannis; Geldner, Niko

2014-01-01

CASPARIAN STRIP MEMBRANE DOMAIN PROTEINS (CASPs) are four-membrane-span proteins that mediate the deposition of Casparian strips in the endodermis by recruiting the lignin polymerization machinery. CASPs show high stability in their membrane domain, which presents all the hallmarks of a membrane scaffold. Here, we characterized the large family of CASP-like (CASPL) proteins. CASPLs were found in all major divisions of land plants as well as in green algae; homologs outside of the plant kingdom were identified as members of the MARVEL protein family. When ectopically expressed in the endodermis, most CASPLs were able to integrate the CASP membrane domain, which suggests that CASPLs share with CASPs the propensity to form transmembrane scaffolds. Extracellular loops are not necessary for generating the scaffold, since CASP1 was still able to localize correctly when either one of the extracellular loops was deleted. The CASP first extracellular loop was found conserved in euphyllophytes but absent in plants lacking Casparian strips, an observation that may contribute to the study of Casparian strip and root evolution. In Arabidopsis (Arabidopsis thaliana), CASPL showed specific expression in a variety of cell types, such as trichomes, abscission zone cells, peripheral root cap cells, and xylem pole pericycle cells. PMID:24920445

Functional and Evolutionary Analysis of the CASPARIAN STRIP MEMBRANE DOMAIN PROTEIN Family.

PubMed

Roppolo, Daniele; Boeckmann, Brigitte; Pfister, Alexandre; Boutet, Emmanuel; Rubio, Maria C; Dénervaud-Tendon, Valérie; Vermeer, Joop E M; Gheyselinck, Jacqueline; Xenarios, Ioannis; Geldner, Niko

2014-08-01

CASPARIAN STRIP MEMBRANE DOMAIN PROTEINS (CASPs) are four-membrane-span proteins that mediate the deposition of Casparian strips in the endodermis by recruiting the lignin polymerization machinery. CASPs show high stability in their membrane domain, which presents all the hallmarks of a membrane scaffold. Here, we characterized the large family of CASP-like (CASPL) proteins. CASPLs were found in all major divisions of land plants as well as in green algae; homologs outside of the plant kingdom were identified as members of the MARVEL protein family. When ectopically expressed in the endodermis, most CASPLs were able to integrate the CASP membrane domain, which suggests that CASPLs share with CASPs the propensity to form transmembrane scaffolds. Extracellular loops are not necessary for generating the scaffold, since CASP1 was still able to localize correctly when either one of the extracellular loops was deleted. The CASP first extracellular loop was found conserved in euphyllophytes but absent in plants lacking Casparian strips, an observation that may contribute to the study of Casparian strip and root evolution. In Arabidopsis (Arabidopsis thaliana), CASPL showed specific expression in a variety of cell types, such as trichomes, abscission zone cells, peripheral root cap cells, and xylem pole pericycle cells. © 2014 American Society of Plant Biologists. All Rights Reserved.

[Construction of the eukaryotic recombinant vector and expression of the outer membrane protein LipL32 gene from Leptospira serovar Lai].

PubMed

Huang, Bi; Bao, Lang; Zhong, Qi; Shang, Zheng-ling; Zhang, Hui-dong; Zhang, Ying

2008-02-01

To construct the eukaryotic experssion vector of LipL32 gene from Leptospira serovar Lai and express the recombinant plasmid in COS-7 cell. The LipL32 gene was amplified from Leptospira strain 017 genomic DNA by PCR and cloned into pcDNA3.1, through restriction nuclease enzyme digestion. Then the recombinant plasmid was transformed into E.coli DH5alpha. After identified by nuclease digestion, PCR and sequencing analysis, the recombinant vector was transfected into COS-7 cell with lipsome. The expression of the target gene was detected by RT-PCR and Western blot. The eukaryotic experssion vector pcDNA3.1-LipL32 was successfully constructed and stably expressed in COS-7 cell. The eukaryotic recombinant vector of outer membrane protein LipL32 gene from Leptospira serovar Lai can be expressed in mammalian cell, which provides an experimental basis for the application of the Leptospira DNA vaccine.

Nippostrongylus brasiliensis: infection induces upregulation of acetylcholinesterase activity on rat intestinal epithelial cells.

PubMed

Russell, W S; Henson, S M; Hussein, A S; Tippins, J R; Selkirk, M E

2000-12-01

Expression of cholines terases and muscarinic acetylcholine receptors in the jejunal mucosa has been investigated during infection of rats with the nematode parasite Nippostrongylus brasiliensis. Selective expression of m3 receptors was observed on epithelial cells from uninfected rats and animals 7 days postinfection, and saturation binding with [(3)H]quinuclidinyl benzilate indicated that receptor expression on cell membranes was unaltered by infection. Butyrylcholinesterase was highly expressed in mucosal epithelia, but acetylcholinesterase was present at low levels in uninfected animals. In contrast, discrete foci of intense acetylcholinesterase activity were observed on the basement membrane of intestinal epithelial cells in animals infected with N. brasiliensis. This was demonstrated to be due to upregulation of expression of endogenous enzyme, which peaked at Day 10 postinfection and subsequently declined to preinfection levels. It is suggested that this occurs in response to hyper-activation of the enteric nervous system as a result of infection, and may benefit the host by limiting excessive fluid secretion due to cholinergic stimulation. Copyright 2000 Academic Press.

Laminin γ3 plays an important role in retinal lamination, photoreceptor organisation and ganglion cell differentiation.

PubMed

Dorgau, Birthe; Felemban, Majed; Sharpe, Alexander; Bauer, Roman; Hallam, Dean; Steel, David H; Lindsay, Susan; Mellough, Carla; Lako, Majlinda

2018-05-23

Laminins are heterotrimeric glycoproteins of the extracellular matrix. Eleven different laminin chains have been identified in vertebrates. They are ubiquitously expressed in the human body, with a distinct tissue distribution. Laminin expression in neural retina and their functional role during human retinogenesis is still unknown. This study investigated the laminin expression in human developing and adult retina, showing laminin α1, α5, β1, β2 and γ1 to be predominantly expressed in Bruch's membrane and the inner limiting membrane. Laminin-332 and laminin γ3 expression were mainly observed in the neural retina during retinal histogenesis. These expression patterns were largely conserved in pluripotent stem cell-derived retinal organoids. Blocking of laminin γ3 function in retinal organoids resulted in the disruption of laminar organisation and synapse formation, the loss of photoreceptor organisation and retinal ganglion cells. Our data demonstrate a unique temporal and spatial expression for laminins and reveal a novel role for laminin γ3 during human retinogenesis.

Interleukin-33 in the Human Placenta

PubMed Central

Topping, Vanessa; Romero, Roberto; Than, Nandor Gabor; Tarca, Adi L.; Xu, Zhonghui; Kim, Sun Young; Wang, Bing; Yeo, Lami; Kim, Chong Jai; Hassan, Sonia S.; Kim, Jung-Sun

2012-01-01

Objective Interleukin-33 (IL-33) is the newest member of the IL-1 cytokine family, a group of key regulators of inflammation. The purpose of this study was to determine whether IL-33 is expressed in the human placenta and to investigate its expression in the context of acute and chronic chorioamnionitis. Methods Placental tissues were obtained from five groups of patients: (1) normal pregnancy at term without labor (n=10); (2) normal pregnancy at term in labor (n=10); (3) preterm labor without inflammation (n=10); (4) preterm labor with acute chorioamnionitis (n=10); and (5) preterm labor with chronic chorioamnionitis (n=10). Immunostaining was performed to determine IL-33 protein expression patterns in the placental disk, chorioamniotic membranes, and umbilical cord. mRNA expression of IL-33 and its receptor IL1RL1 (ST2) was measured in primary amnion epithelial and mesenchymal cells (AECs and AMCs, n=4) and human umbilical vein endothelial cells (HUVECs, n=4) treated with IL-1β (1ng/ml and 10ng/ml) and CXCL10 (0.5ng/ml and 1ng/ml or 5ng/ml). Results 1) Nuclear IL-33 expression was found in endothelial and smooth muscle cells in the placenta, chorioamniotic membranes, and umbilical cord; 2) IL-33 was detected in the nucleus of CD14+ macrophages in the chorioamniotic membranes, chorionic plate, and umbilical cord, and in the cytoplasm of myofibroblasts in the Wharton’s jelly; 3) acute (but not chronic) chorioamnionitis was associated with the presence of IL-33+ macrophages in the chorioamniotic membranes and umbilical cord; 4) expression of IL-33 or IL1RL1 (ST2) mRNA in AECs was undetectable; 5) IL-33 mRNA expression increased in AMCs and HUVECs after IL-1β treatment but did not change with CXCL10 treatment; and 6) IL1RL1 (ST2) expression decreased in AMCs and increased in HUVECs after IL-1β but not CXCL10 treatment. Conclusions IL-33 is expressed in the nucleus of placental endothelial cells, CD14+ macrophages, and myofibroblasts in the Wharton’s jelly. IL-1β can induce the expression of IL-33 and its receptor. Protein expression of IL-33 is detectable in macrophages of the chorioamniotic membranes in acute (but not chronic) chorioamnionitis. PMID:23039129

P2X7 receptors regulate multiple types of membrane trafficking responses and non-classical secretion pathways.

PubMed

Qu, Yan; Dubyak, George R

2009-06-01

Activation of the P2X7 receptor (P2X7R) triggers a remarkably diverse array of membrane trafficking responses in leukocytes and epithelial cells. These responses result in altered profiles of cell surface lipid and protein composition that can modulate the direct interactions of P2X7R-expressing cells with other cell types in the circulation, in blood vessels, at epithelial barriers, or within sites of immune and inflammatory activation. Additionally, these responses can result in the release of bioactive proteins, lipids, and large membrane complexes into extracellular compartments for remote communication between P2X7R-expressing cells and other cells that amplify or modulate inflammation, immunity, and responses to tissue damages. This review will discuss P2X7R-mediated effects on membrane composition and trafficking in the plasma membrane (PM) and intracellular organelles, as well as actions of P2X7R in controlling various modes of non-classical secretion. It will review P2X7R regulation of: (1) phosphatidylserine distribution in the PM outer leaflet; (2) shedding of PM surface proteins; (3) release of PM-derived microvesicles or microparticles; (4) PM blebbing; (5) cell-cell fusion resulting in formation of multinucleate cells; (6) phagosome maturation and fusion with lysosomes; (7) permeability of endosomes with internalized pathogen-associated molecular patterns; (8) permeability/integrity of mitochondria; (9) exocytosis of secretory lysosomes; and (10) release of exosomes from multivesicular bodies.

Constitutive expression of the maltoporin LamB in the absence of OmpR damages the cell envelope.

PubMed

Reimann, Sylvia A; Wolfe, Alan J

2011-02-01

Cells experience multiple environmental stimuli simultaneously. To survive, they must respond accordingly. Unfortunately, the proper response to one stress easily could make the cell more susceptible to a second coexistent stress. To deal with such a problem, a cell must possess a mechanism that balances the need to respond simultaneously to both stresses. Our recent studies of ompR malT(Con) double mutants show that elevated expression of LamB, the outer membrane porin responsible for maltose uptake, causes cell death when the osmoregulator OmpR is disabled. To obtain insight into the nature of the death experienced by ompR malT(Con) mutants, we described the death process. On the basis of microscopic and biochemical approaches, we conclude that death results from a loss of membrane integrity. On the basis of an unbiased genome-wide search for suppressor mutations, we conclude that this loss of membrane integrity results from a LamB-induced envelope stress that the cells do not sufficiently perceive and thus do not adequately accommodate. Finally, we conclude that this envelope stress involves an imbalance in the lipopolysaccharide/porin composition of the outer membrane and an increased requirement for inorganic phosphate.

Neisseria gonorrhoeae PIII has a role on NG1873 outer membrane localization and is involved in bacterial adhesion to human cervical and urethral epithelial cells.

PubMed

Leuzzi, Rosanna; Nesta, Barbara; Monaci, Elisabetta; Cartocci, Elena; Serino, Laura; Soriani, Marco; Rappuoli, Rino; Pizza, Mariagrazia

2013-11-09

Protein PIII is one of the major outer membrane proteins of Neisseria gonorrhoeae, 95% identical to RmpM (reduction modifiable protein M) or class 4 protein of Neisseria meningitidis. RmpM is known to be a membrane protein associated by non-covalent bonds to the peptidoglycan layer and interacting with PorA/PorB porin complexes resulting in the stabilization of the bacterial membrane. The C-terminal domain of PIII (and RmpM) is highly homologous to members of the OmpA family, known to have a role in adhesion/invasion in many bacterial species. The contribution of PIII in the membrane architecture and its role in the interaction with epithelial cells has never been investigated. We generated a ΔpIII knock-out mutant strain and evaluated the effects of the loss of PIII expression on bacterial morphology and on outer membrane composition. Deletion of the pIII gene does not cause any alteration in bacterial morphology or sensitivity to detergents. Moreover, the expression profile of the main membrane proteins remains the same for the wild-type and knock-out strains, with the exception of the NG1873 which is not exported to the outer membrane and accumulates in the inner membrane in the ΔpIII knock-out mutant strain.We also show that purified PIII protein is able to bind human cervical and urethral cells and that the ΔpIII knock-out mutant strain has a lower ability to adhere to human cervical and urethral cells. Here we demonstrated that the PIII protein does not play a key structural role in the membrane organization of gonococcus and does not induce major effects on the expression of the main outer membrane proteins. However, in the PIII knock-out strain, the NG1873 protein is not localized in the outer membrane as it is in the wild-type strain suggesting a possible interaction of PIII with NG1873. The evidence that PIII binds to human epithelial cells derived from the female and male genital tract highlights a possible role of PIII in the virulence of gonococcus and suggests that the structural homology to OmpA is conserved also at functional level.

Reproductive organ and vascular specific promoter of the rice plasma membrane Ca2+ATPase mediates environmental stress responses in plants.

PubMed

Huda, Kazi Md Kamrul; Banu, Mst Sufara Akhter; Pathi, Krishna Mohan; Tuteja, Narendra

2013-01-01

Plasma membrane Ca(2+)ATPase is a transport protein in the plasma membrane of cells and helps in removal of calcium (Ca(2+)) from the cell, hence regulating Ca(2+) level within cells. Though plant Ca(2+)ATPases have been shown to be involved in plant stress responses but their promoter regions have not been well studied. The 1478 bp promoter sequence of rice plasma membrane Ca(2+)ATPase contains cis-acting elements responsive to stresses and plant hormones. To identify the functional region, serial deletions of the promoter were fused with the GUS sequence and four constructs were obtained. These were differentially activated under NaCl, PEG cold, methyl viologen, abscisic acid and methyl jasmonate treatments. We demonstrated that the rice plasma membrane Ca(2+)ATPase promoter is responsible for vascular-specific and multiple stress-inducible gene expression. Only full-length promoter showed specific GUS expression under stress conditions in floral parts. High GUS activity was observed in roots with all the promoter constructs. The -1478 to -886 bp flanking region responded well upon treatment with salt and drought. Only the full-length promoter presented cold-induced GUS expression in leaves, while in shoots slight expression was observed for -1210 and -886 bp flanking region. The -1210 bp deletion significantly responded to exogenous methyl viologen and abscisic acid induction. The -1210 and -886 bp flanking region resulted in increased GUS activity in leaves under methyl jasmonate treatments, whereas in shoots the -886 bp and -519 bp deletion gave higher expression. Salicylic acid failed to induce GUS activities in leaves for all the constructs. The rice plasma membrane Ca(2+)ATPase promoter is a reproductive organ-specific as well as vascular-specific. This promoter contains drought, salt, cold, methyl viologen, abscisic acid and methyl jasmonate related cis-elements, which regulated gene expression. Overall, the tissue-specificity and inducible nature of this promoter could grant wide applicability in plant biotechnology.

Molecular evidence for a role for K+-Cl− cotransporters in the kidney

PubMed Central

Melo, Zesergio; Cruz-Rangel, Silvia; Bautista, Rocio; Vázquez, Norma; Castañeda-Bueno, María; Mount, David B.; Pasantes-Morales, Herminia; Mercado, Adriana

2013-01-01

K+-Cl− cotransporter (KCC) isoforms 3 (KCC3) and 4 (KCC4) are expressed at the basolateral membrane of proximal convoluted tubule cells, and KCC4 is present in the basolateral membrane of the thick ascending loop of Henle's limb and α-intercalated cells of the collecting duct. Little is known, however, about the physiological roles of these transporters in the kidney. We evaluated KCC3 and KCC4 mRNA and protein expression levels and intrarenal distribution in male Wistar rats or C57 mice under five experimental conditions: hyperglycemia after a single dose of streptozotocin, a low-salt diet, metabolic acidosis induced by ammonium chloride in drinking water, and low- or high-K+ diets. Both KCC3 mRNA and protein expression were increased during hyperglycemia in the renal cortex and at the basolateral membrane of proximal tubule cells but not with a low-salt diet or acidosis. In contrast, KCC4 protein expression was increased by a low-sodium diet in the whole kidney and by metabolic acidosis in the renal outer medulla, specifically at the basolateral membrane of α-intercalated cells. The increased protein expression of KCC4 by a low-salt diet was also observed in WNK4 knockout mice, suggesting that upregulation of KCC4 in these circumstances is not WNK4 dependent. No change in KCC3 or KCC4 protein expression was observed under low- or high-K+ diets. Our data are consistent with a role for KCC3 in the proximal tubule glucose reabsorption mechanism and for KCC4 in salt reabsorption of the thick ascending loop of Henle's loop and acid secretion of the collecting duct. PMID:24089410

Membrane penetrating peptides greatly enhance baculovirus transduction efficiency into mammalian cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hong-Zhang; Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan, ROC; Wu, Carol P.

2011-02-11

Research highlights: {yields} Ligation of CTP with GP64 enhances baculovirus transduction into mammalian cells. {yields} Fusion of PTD with VP39 enhances baculovirus transduction into mammalian cells. {yields} CTP and PTD-carrying viruses improve the transduction of co-transduced baculoviruses. {yields} Virus entry and gene expression can be separate events in different cell types. -- Abstract: The baculovirus group of insect viruses is widely used for foreign gene introduction into mammalian cells for gene expression and protein production; however, the efficiency of baculovirus entry into mammalian cells is in general still low. In this study, two recombinant baculoviruses were engineered and their abilitymore » to improve viral entry was examined: (1) cytoplasmic transduction peptide (CTP) was fused with baculovirus envelope protein, GP64, to produce a cytoplasmic membrane penetrating baculovirus (vE-CTP); and (2) the protein transduction domain (PTD) of HIV TAT protein was fused with the baculovirus capsid protein VP39 to form a nuclear membrane penetrating baculovirus (vE-PTD). Transduction experiments showed that both viruses had better transduction efficiency than vE, a control virus that only expresses EGFP in mammalian cells. Interestingly, vE-CTP and vE-PTD were also able to improve the transduction efficiency of a co-transduced baculovirus, resulting in higher levels of gene expression. Our results have described new routes to further enhance the development of baculovirus as a tool for gene delivery into mammalian cells.« less

Differential Expression and Immunolocalization of Antioxidant Enzymes in Entamoeba histolytica Isolates during Metronidazole Stress

PubMed Central

Iyer, Lakshmi Rani; Singh, Nishant; Verma, Anil Kumar; Paul, Jaishree

2014-01-01

Entamoeba histolytica infections are endemic in the Indian subcontinent. Five to eight percent of urban population residing under poor sanitary conditions suffers from Entamoeba infections. Metronidazole is the most widely prescribed drug used for amoebiasis. In order to understand the impact of metronidazole stress on the parasite, we evaluated the expression of two antioxidant enzymes, peroxiredoxin and FeSOD, in Entamoeba histolytica isolates during metronidazole stress. The results reveal that, under metronidazole stress, the mRNA expression levels of these enzymes did not undergo any significant change. Interestingly, immunolocalization studies with antibodies targeting peroxiredoxin indicate differential localization of the protein in the cell during metronidazole stress. In normal conditions, all the Entamoeba isolates exhibit presence of peroxiredoxin in the nucleus as well as in the membrane; however with metronidazole stress the protein localized mostly to the membrane. The change in the localization pattern was more pronounced when the cells were subjected to short term metronidazole stress compared to cells adapted to metronidazole. The protein localization to the cell membrane could be the stress response mechanism in these isolates. Colocalization pattern of peroxiredoxin with CaBp1, a cytosolic protein, revealed that the membrane and nuclear localization was specific to peroxiredoxin during metronidazole stress. PMID:25013795

Characterization of femtosecond-laser pulse induced cell membrane nanosurgical attachment.

PubMed

Katchinskiy, Nir; Godbout, Roseline; Elezzabi, Abdulhakem Y

2016-07-01

This article provides insight into the mechanism of femtosecond laser nanosurgical attachment of cells. We have demonstrated that during the attachment of two retinoblastoma cells using sub-10 femtosecond laser pulses, with 800 nm central wavelength, the phospholipid molecules of both cells hemifuse and form one shared phospholipid bilayer, at the attachment location. In order to verify the hypothesis that hemifusion takes place, transmission electron microscope images of the cell membranes of retinoblastoma cells were taken. It is shown that at the attachment interface, the two cell membranes coalesce and form one single membrane shared by both cells. Thus, further evidence is provided to support the hypothesis that laser-induced ionization process led to an ultrafast reversible destabilization of the phospholipid layer of the cellular membrane, which resulted in cross-linking of the phospholipid molecules in each membrane. This process of hemifusion occurs throughout the entire penetration depth of the femtosecond laser pulse train. Thus, the attachment between the cells takes place across a large surface area, which affirms our findings of strong physical attachment between the cells. The femtosecond laser pulse hemifusion technique can potentially provide a platform for precise molecular manipulation of cellular membranes. Manipulation of the cellular membrane is an important procedure that could aid in studying diseases such as cancer; where the expression level of plasma proteins on the cell membrane is altered.

EMP-1 is a junctional protein in a liver stem cell line and in the liver.

PubMed

Lee, Hsuan-Shu; Sherley, James L; Chen, Jeremy J W; Chiu, Chien-Chang; Chiou, Ling-Ling; Liang, Ja-Der; Yang, Pan-Chyr; Huang, Guan-Tarn; Sheu, Jin-Chuan

2005-09-09

In an attempt to discover cell markers for liver stem cells, a cDNA microarray analysis was carried out to compare the gene expression profiles between an adult liver stem cell line, Lig-8, and mature hepatocytes. Several genes in the categories of extracellular matrix, cell membrane, cell adhesion, transcription factor, signal molecule, transporter, and metabolic enzyme were shown to be differentially expressed in Lig-8 cells. Among them, epithelial membrane protein (EMP)-1 has been previously implicated with stem cell phenotypes. Antiserum to EMP-1 was produced to localize its expression. On monolayers of Lig-8 cells, EMP-1 was expressed along the intercellular border. In the liver harboring proliferating oval cells, the liver progenitors, EMP-1 was localized as ribbon bands, a staining pattern for epithelial junctions, all the way through bile duct epithelia, oval cell ductules, and into peri-hepatocytic regions. These peri-hepatocytic regions were proved to be bile canaliculi by co-localization of EMP-1 and dipeptidyl peptidase IV, an enzyme located on bile canaliculi. This report is the first to indicate EMP-1 to be a junctional protein in the liver.

Multifaceted plasma membrane Ca(2+) pumps: From structure to intracellular Ca(2+) handling and cancer.

PubMed

Padányi, Rita; Pászty, Katalin; Hegedűs, Luca; Varga, Karolina; Papp, Béla; Penniston, John T; Enyedi, Ágnes

2016-06-01

Plasma membrane Ca(2+) ATPases (PMCAs) are intimately involved in the control of intracellular Ca(2+) concentration. They reduce Ca(2+) in the cytosol not only by direct ejection, but also by controlling the formation of inositol-1,4,5-trisphosphate and decreasing Ca(2+) release from the endoplasmic reticulum Ca(2+) pool. In mammals four genes (PMCA1-4) are expressed, and alternative RNA splicing generates more than twenty variants. The variants differ in their regulatory characteristics. They localize into highly specialized membrane compartments and respond to the incoming Ca(2+) with distinct temporal resolution. The expression pattern of variants depends on cell type; a change in this pattern can result in perturbed Ca(2+) homeostasis and thus altered cell function. Indeed, PMCAs undergo remarkable changes in their expression pattern during tumorigenesis that might significantly contribute to the unbalanced Ca(2+) homeostasis of cancer cells. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen. Copyright © 2015 Elsevier B.V. All rights reserved.

Functional Characterization of Na+/H+ Exchangers of Intracellular Compartments Using Proton-killing Selection to Express Them at the Plasma Membrane

PubMed Central

Monet, Michael; Birgy-Barelli, Eléonore; Léna, Isabelle; Counillon, Laurent

2015-01-01

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and neurotransmitter loading in synaptic vesicles. This acidification is described to be mediated by proton ATPases, coupled to ClC chloride transporters. Highly-conserved electroneutral protons transporters, the Na+/H+ exchangers (NHE) 6, 7 and 9 are also expressed in these compartments. Mutations in their genes have been linked with human cognitive and neurodegenerative diseases. Paradoxically, their roles remain elusive, as their intracellular localization has prevented detailed functional characterization. This manuscript shows a method to solve this problem. This consists of the selection of mutant cell lines, capable of surviving acute cytosolic acidification by retaining intracellular NHEs at the plasma membrane. It then depicts two complementary protocols to measure the ion selectivity and activity of these exchangers: (i) one based on intracellular pH measurements using fluorescence video microscopy, and (ii) one based on the fast kinetics of lithium uptake. Such protocols can be extrapolated to measure other non-electrogenic transporters. Furthermore, the selection procedure presented here generates cells with an intracellular retention defective phenotype. Therefore these cells will also express other vesicular membrane proteins at the plasma membrane. The experimental strategy depicted here may therefore constitute a potentially powerful tool to study other intracellular proteins that will be then expressed at the plasma membrane together with the vesicular Na+/H+ exchangers used for the selection. PMID:25867523

Functional characterization of Na+/H+ exchangers of intracellular compartments using proton-killing selection to express them at the plasma membrane.

PubMed

Milosavljevic, Nina; Poët, Mallorie; Monet, Michael; Birgy-Barelli, Eléonore; Léna, Isabelle; Counillon, Laurent

2015-03-30

Endosomal acidification is critical for a wide range of processes, such as protein recycling and degradation, receptor desensitization, and neurotransmitter loading in synaptic vesicles. This acidification is described to be mediated by proton ATPases, coupled to ClC chloride transporters. Highly-conserved electroneutral protons transporters, the Na+/H+ exchangers (NHE) 6, 7 and 9 are also expressed in these compartments. Mutations in their genes have been linked with human cognitive and neurodegenerative diseases. Paradoxically, their roles remain elusive, as their intracellular localization has prevented detailed functional characterization. This manuscript shows a method to solve this problem. This consists of the selection of mutant cell lines, capable of surviving acute cytosolic acidification by retaining intracellular NHEs at the plasma membrane. It then depicts two complementary protocols to measure the ion selectivity and activity of these exchangers: (i) one based on intracellular pH measurements using fluorescence video microscopy, and (ii) one based on the fast kinetics of lithium uptake. Such protocols can be extrapolated to measure other non-electrogenic transporters. Furthermore, the selection procedure presented here generates cells with an intracellular retention defective phenotype. Therefore these cells will also express other vesicular membrane proteins at the plasma membrane. The experimental strategy depicted here may therefore constitute a potentially powerful tool to study other intracellular proteins that will be then expressed at the plasma membrane together with the vesicular Na+/H+ exchangers used for the selection.

Expression of mammalian beta-adrenergic receptors in Xenopus laevis oocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahouth, S.W.; Malbon, C.C.

1987-05-01

Xenopus laevis oocytes are a useful transcription and expression system for DNA and RNA, respectively. Total cellular RNA was extracted from mouse lymphoma S49 cells and poly(A)/sup +/mRNA prepared by affinity chromatography of RNA on oligo(dT) cellulose. The membranes of S49 cells contain beta-adrenergic receptors that display pharmacological characteristics of beta/sub 2/-subtype. Xenopus laevis oocytes were injected with 50 ng of mRNA/oocyte. Expression of beta-adrenergic receptors in oocytes incubated for 30 hr after microinjection was assessed in membranes by radioligand binding using (/sup 3/H) dihydroalprenolol. The injected oocytes displayed 0.34 fmol receptor/oocyte as compared to 0.02 fmol receptor/oocyte in themore » control oocytes. The affinity of beta-adrenergic receptors in injected oocytes for this radioligand was 2 nM, a value similar to the affinity of beta-adrenergic receptors for DHA in S49 cell membranes. The potency of beta-adrenergic agonists in competing for DHA binding to oocytes membranes was isoproterenol > epinephrine > norepineprine, indicating that the expressed beta-adrenergic receptors were of the beta/sub 2/-subtype. The K/sub I/ of these agonists for the beta-adrenergic receptor in oocyte membranes was 0.03, 0.15 and 1.2 ..mu..M, respectively. The role of post-translational modification in dictating receptor subtype is analyzed using mRNA of beta/sub 1/- as well as beta/sub 2/-adrenergic receptors.« less

ERp29 Regulates ΔF508 and Wild-type Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Trafficking to the Plasma Membrane in Cystic Fibrosis (CF) and Non-CF Epithelial Cells*

PubMed Central

Suaud, Laurence; Miller, Katelyn; Alvey, Lora; Yan, Wusheng; Robay, Amal; Kebler, Catherine; Kreindler, James L.; Guttentag, Susan; Hubbard, Michael J.; Rubenstein, Ronald C.

2011-01-01

Sodium 4-phenylbutyrate (4PBA) improves the intracellular trafficking of ΔF508-CFTR in cystic fibrosis (CF) epithelial cells. The underlying mechanism is uncertain, but 4PBA modulates the expression of some cytosolic molecular chaperones. To identify other 4PBA-regulated proteins that might regulate ΔF508-CFTR trafficking, we performed a differential display RT-PCR screen on IB3-1 CF bronchiolar epithelial cells exposed to 4PBA. One transcript up-regulated by 4PBA encoded ERp29, a luminal resident of the endoplasmic reticulum (ER) thought to be a novel molecular chaperone. We tested the hypothesis that ERp29 is a 4PBA-regulated ER chaperone that influences ΔF508-CFTR trafficking. ERp29 mRNA and protein expression was significantly increased (∼1.5-fold) in 4PBA-treated IB3-1 cells. In Xenopus oocytes, ERp29 overexpression increased the functional expression of both wild-type and ΔF508-CFTR over 3-fold and increased wild-type cystic fibrosis transmembrane conductance regulator (CFTR) plasma membrane expression. In CFBE41o− WT-CFTR cells, expression of and short circuit currents mediated by CFTR decreased upon depletion of ERp29 as did maturation of newly synthesized CFTR. In IB3-1 cells, ΔF508-CFTR co-immunoprecipitated with endogenous ERp29, and overexpression of ERp29 led to increased ΔF508-CFTR expression at the plasma membrane. These data suggest that ERp29 is a 4PBA-regulated ER chaperone that regulates WT-CFTR biogenesis and can promote ΔF508-CFTR trafficking in CF epithelial cells. PMID:21525008

ERp29 regulates DeltaF508 and wild-type cystic fibrosis transmembrane conductance regulator (CFTR) trafficking to the plasma membrane in cystic fibrosis (CF) and non-CF epithelial cells.

PubMed

Suaud, Laurence; Miller, Katelyn; Alvey, Lora; Yan, Wusheng; Robay, Amal; Kebler, Catherine; Kreindler, James L; Guttentag, Susan; Hubbard, Michael J; Rubenstein, Ronald C

2011-06-17

Sodium 4-phenylbutyrate (4PBA) improves the intracellular trafficking of ΔF508-CFTR in cystic fibrosis (CF) epithelial cells. The underlying mechanism is uncertain, but 4PBA modulates the expression of some cytosolic molecular chaperones. To identify other 4PBA-regulated proteins that might regulate ΔF508-CFTR trafficking, we performed a differential display RT-PCR screen on IB3-1 CF bronchiolar epithelial cells exposed to 4PBA. One transcript up-regulated by 4PBA encoded ERp29, a luminal resident of the endoplasmic reticulum (ER) thought to be a novel molecular chaperone. We tested the hypothesis that ERp29 is a 4PBA-regulated ER chaperone that influences ΔF508-CFTR trafficking. ERp29 mRNA and protein expression was significantly increased (∼1.5-fold) in 4PBA-treated IB3-1 cells. In Xenopus oocytes, ERp29 overexpression increased the functional expression of both wild-type and ΔF508-CFTR over 3-fold and increased wild-type cystic fibrosis transmembrane conductance regulator (CFTR) plasma membrane expression. In CFBE41o- WT-CFTR cells, expression of and short circuit currents mediated by CFTR decreased upon depletion of ERp29 as did maturation of newly synthesized CFTR. In IB3-1 cells, ΔF508-CFTR co-immunoprecipitated with endogenous ERp29, and overexpression of ERp29 led to increased ΔF508-CFTR expression at the plasma membrane. These data suggest that ERp29 is a 4PBA-regulated ER chaperone that regulates WT-CFTR biogenesis and can promote ΔF508-CFTR trafficking in CF epithelial cells.

Novel Tonoplast Transporters Identified Using a Proteomic Approach with Vacuoles Isolated from Cauliflower Buds1[W][OA

PubMed Central

Schmidt, Ulrike G.; Endler, Anne; Schelbert, Silvia; Brunner, Arco; Schnell, Magali; Neuhaus, H. Ekkehard; Marty-Mazars, Daniéle; Marty, Francis; Baginsky, Sacha; Martinoia, Enrico

2007-01-01

Young meristematic plant cells contain a large number of small vacuoles, while the largest part of the vacuome in mature cells is composed by a large central vacuole, occupying 80% to 90% of the cell volume. Thus far, only a limited number of vacuolar membrane proteins have been identified and characterized. The proteomic approach is a powerful tool to identify new vacuolar membrane proteins. To analyze vacuoles from growing tissues we isolated vacuoles from cauliflower (Brassica oleracea) buds, which are constituted by a large amount of small cells but also contain cells in expansion as well as fully expanded cells. Here we show that using purified cauliflower vacuoles and different extraction procedures such as saline, NaOH, acetone, and chloroform/methanol and analyzing the data against the Arabidopsis (Arabidopsis thaliana) database 102 cauliflower integral proteins and 214 peripheral proteins could be identified. The vacuolar pyrophosphatase was the most prominent protein. From the 102 identified proteins 45 proteins were already described. Nine of these, corresponding to 46% of peptides detected, are known vacuolar proteins. We identified 57 proteins (55.9%) containing at least one membrane spanning domain with unknown subcellular localization. A comparison of the newly identified proteins with expression profiles from in silico data revealed that most of them are highly expressed in young, developing tissues. To verify whether the newly identified proteins were indeed localized in the vacuole we constructed and expressed green fluorescence protein fusion proteins for five putative vacuolar membrane proteins exhibiting three to 11 transmembrane domains. Four of them, a putative organic cation transporter, a nodulin N21 family protein, a membrane protein of unknown function, and a senescence related membrane protein were localized in the vacuolar membrane, while a white-brown ATP-binding cassette transporter homolog was shown to reside in the plasma membrane. These results demonstrate that proteomic analysis of highly purified vacuoles from specific tissues allows the identification of new vacuolar proteins and provides an additional view of tonoplastic proteins. PMID:17660356

NIS expression in thyroid tumors, relation with prognosis clinicopathological and molecular features

PubMed Central

Tavares, Catarina; Coelho, Maria João; Eloy, Catarina; Melo, Miguel; da Rocha, Adriana Gaspar; Pestana, Ana; Batista, Rui; Ferreira, Luciana Bueno; Rios, Elisabete; Selmi-Ruby, Samia; Cavadas, Bruno; Pereira, Luísa; Sobrinho Simões, Manuel

2018-01-01

Thyroid cancer therapy is based on surgery followed by radioiodine treatment. The incorporation of radioiodine by cancer cells is mediated by sodium iodide symporter (NIS) (codified by the SLC5A5 gene), that is functional only when targeted to the cell membrane. We aimed to evaluate if NIS expression in thyroid primary tumors would be helpful in predicting tumor behavior, response to therapy and prognosis. NIS expression was addressed by qPCR and immunohistochemistry. In order to validate our data, we also studied SLC5A5 expression on 378 primary papillary thyroid carcinomas from The Cancer Genome Atlas (TCGA) database. In our series, SLC5A5 expression was lower in carcinomas with vascular invasion and with extrathyroidal extension and in those harboring BRAFV600E mutation. Analysis of SLC5A5 expression from TCGA database confirmed our results. Furthermore, it showed that larger tumors, with locoregional recurrences and/or distant metastases or harboring RAS, BRAF and/or TERT promoter (TERTp) mutations presented significantly less SLC5A5 expression. Regarding immunohistochemistry, 12/211 of the cases demonstrated NIS in the membrane of tumor cells, those cases showed variable outcomes concerning therapy success, prognosis and all but one were wild type for BRAF, NRAS and TERTp mutations. SLC5A5 mRNA lower expression is associated with features of aggressiveness and with key genetic alterations involving BRAF, RAS and TERTp. Mutations in these genes seem to decrease protein expression and its targeting to the cell membrane. SLC5A5 mRNA expression is more informative than NIS immunohistochemical expression regarding tumor aggressiveness and prognostic features. PMID:29298843

Evaluation of RPE65, CRALBP, VEGF, CD68, and tyrosinase gene expression in human retinal pigment epithelial cells cultured on amniotic membrane.

PubMed

Akrami, Hassan; Soheili, Zahra-Soheila; Sadeghizadeh, Majid; Khalooghi, Keynoush; Ahmadieh, Hamid; Kanavi, Mojgan Rezaie; Samiei, Shahram; Pakravesh, Jalil

2011-06-01

The retinal pigment epithelium (RPE) plays a key role in the maintenance of the normal functions of the retina. Tissue engineering using amniotic membrane as a substrate to culture RPE cells may provide a promising new strategy to replace damaged RPE. We established a method of culturing RPE cells over the amniotic membrane as a support for their growth and transplantation. The transcription of specific genes involved in cellular function of native RPE, including RPE65, CRALBP, VEGF, CD68, and tyrosinase, were then measured using quantitative real-time PCR. Data showed a considerable increase in transcription of RPE65, CD68, and VEGF in RPE cells cultured on amniotic membrane. The amounts of CRALBP and tyrosinase transcripts were not affected. This may simply indicate that amniotic membrane restricted dedifferentiation of RPE cells in culture. The results suggest that amniotic membrane may be considered as an elective biological substrate for RPE cell culture.

Epstein-Barr Virus Latent Membrane Protein 2A (LMP2A)-Mediated changes in Fas Expression and Fas-Dependent Apoptosis: Role of Lyn/Syk activation

PubMed Central

Incrocci, Ryan; Hussain, Samira; Stone, Amanda; Bieging, Kathryn; Alt, Lauren A.C.; Fay, Michael J.; Swanson-Mungerson, Michelle

2015-01-01

Epstein-Barr virus Latent Membrane Protein 2A (LMP2A) is expressed in EBV-infected B cells in the germinal center, a site of significant apoptosis induced by engagement of Fas on activated B cells. Signals from the B cell receptor (BCR) protect germinal center B cells from Fas-mediated apoptosis, and since LMP2A is a BCR mimic, we hypothesized that LMP2A would also protect B cells from Fas-mediated apoptosis. Surprisingly, latently-infected human and murine B cell lines expressing LMP2A were more sensitive to Fas-mediated apoptosis, as determined by increases in Annexin-V staining, and cleavage of caspase-8, −3 and PARP. Additional studies show that LMP2A-expressing B cell lines demonstrate a Lyn- and Syk-dependent increase in sensitivity to Fas-mediated apoptosis, due to an LMP2A-dependent enhancement in Fas expression. These findings demonstrate the ability for LMP2A to directly increase a pro-apoptotic molecule and have implications for EBV latency as well as the treatment of EBV-associated malignancies. PMID:26255694

Expression of membrane-associated proteins within single emulsion cell facsimiles.

PubMed

Chanasakulniyom, Mayuree; Martino, Chiara; Paterson, David; Horsfall, Louise; Rosser, Susan; Cooper, Jonathan M

2012-07-07

MreB is a structural membrane-associated protein which is one of the key components of the bacterial cytoskeleton. Although it plays an important role in shape maintenance of rod-like bacteria, the understanding of its mechanism of action is still not fully understood. This study shows how segmented flow and microdroplet technology can be used as a new tool for biological in vitro investigation of this protein. In this paper, we demonstrate cell-free expression in a single emulsion system to express red fluorescence protein (RFP) and MreB linked RFP (MreB-RFP). We follow the aggregation and localisation of the fusion protein MreB-RFP in this artificial cell-like environment. The expression of MreB-RFP in single emulsion droplets leads to the formation of micrometer-scale protein patches distributed at the water/oil interface.

Zinc oxide nanoparticles decrease the expression and activity of plasma membrane calcium ATPase, disrupt the intracellular calcium homeostasis in rat retinal ganglion cells.

PubMed

Guo, Dadong; Bi, Hongsheng; Wang, Daoguang; Wu, Qiuxin

2013-08-01

Zinc oxide nanoparticle is one of the most important materials with diverse applications. However, it has been reported that zinc oxide nanoparticles are toxic to organisms, and that oxidative stress is often hypothesized to be an important factor in cytotoxicity mediated by zinc oxide nanoparticles. Nevertheless, the mechanism of toxicity of zinc oxide nanoparticles has not been completely understood. In this study, we investigated the cytotoxic effect of zinc oxide nanoparticles and the possible molecular mechanism involved in calcium homeostasis mediated by plasma membrane calcium ATPase in rat retinal ganglion cells. Real-time cell electronic sensing assay showed that zinc oxide nanoparticles could exert cytotoxic effect on rat retinal ganglion cells in a concentration-dependent manner; flow cytometric analysis indicated that zinc oxide nanoparticles could lead to cell damage by inducing the overproduction of reactive oxygen species. Furthermore, zinc oxide nanoparticles could also apparently decrease the expression level and their activity of plasma membrane calcium ATPase, which finally disrupt the intracellular calcium homeostasis and result in cell death. Taken together, zinc oxide nanoparticles could apparently decrease the plasma membrane calcium ATPase expression, inhibit their activity, cause the elevated intracellular calcium ion level and disrupt the intracellular calcium homeostasis. Further, the disrupted calcium homeostasis will trigger mitochondrial dysfunction, generate excessive reactive oxygen species, and finally initiate cell death. Thus, the disrupted calcium homeostasis is involved in the zinc oxide nanoparticle-induced rat retinal ganglion cell death. Copyright © 2013 Elsevier Ltd. All rights reserved.

EMMPRIN/CD147-encriched membrane vesicles released from malignant human testicular germ cells increase MMP production through tumor-stroma interaction.

PubMed

Milia-Argeiti, Eleni; Mourah, Samia; Vallée, Benoit; Huet, Eric; Karamanos, Nikos K; Theocharis, Achilleas D; Menashi, Suzanne

2014-08-01

Elevated levels of EMMPRIN/CD147 in cancer tissues have been correlated with tumor progression but the regulation of its expression is not yet understood. Here, the regulation of EMMPRIN expression was investigated in testicular germ cell tumor (TGCTs) cell lines. EMMPRIN expression in seminoma JKT-1 and embryonal carcinoma NT2/D1 cell lines was determined by Western blot, immunofluorescence and qRT-PCR. Membrane vesicles (MVs) secreted from these cells, treated or not with EMMPRIN siRNA, were isolated by differential centrifugations of their conditioned medium. MMP-2 was analyzed by zymography and qRT-PCR. The more aggressive embryonic carcinoma NT2/D1 cells expressed more EMMPRIN mRNA than the seminoma JKT-1 cells, but surprisingly contained less EMMPRIN protein, as determined by immunoblotting and immunostaining. The protein/mRNA discrepancy was not due to accelerated protein degradation in NT2/D1 cells, but by the secretion of EMMPRIN within MVs, as the vesicles released from NT2/D1 contained considerably more EMMPRIN than those released from JKT-1. EMMPRIN-containing MVs obtained from NT2/D1, but not from EMMPRIN-siRNA treated NT2/D1, increased MMP-2 production in fibroblasts to a greater extent than those from JKT-1 cells. The data presented show that the more aggressive embryonic carcinoma cells synthesize more EMMPRIN than seminoma cells, but which they preferentially target to secreted MVs, unlike seminoma cells which retain EMMPRIN within the cell membrane. This cellular event points to a mechanism by which EMMPRIN expressed by malignant testicular cells can exert its MMP inducing effect on distant cells within the tumor microenvironment to promote tumor invasion. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Expression of membrane-bound mucins in human nasal mucosa: different patterns for MUC4 and MUC16.

PubMed

Woo, Hyun-Jae; Bae, Chang Hoon; Song, Si-Youn; Lee, Heung-Man; Kim, Yong-Dae

2010-06-01

To acquire basic information concerning the function of the membrane-bound mucin MUC16 in nasal mucosa compared with the best-characterized membrane-bound mucin, MUC4. In vitro study using semiquantatitive reverse transcription-polymerase chain reaction analysis and immunoassay. Yeungnam University College of Medicine. We examined the nasal polyps obtained during endoscopic sinus surgery in 10 patients, the normal ethmoid sinus mucosa obtained from 10 patients, and human nasal polyp epithelial (HNPE) cells. Gene expression of MUC4 and MUC16 in nasal polyps and normal nasal mucosa. In addition, we evaluated the effect of 4 physiologically relevant agents, including retinoic acid, interleukin 1beta, phorbol 12-myristate 13-acetate (PMA), and dexamethasone, on the expression of MUC4 and MUC16 in HNPE cells at the gene and protein levels. In nasal polyps, MUC4 was upregulated compared with normal nasal mucosa (P = .009), whereas MUC16 expression did not differ between nasal polyps and normal nasal mucosa. Retinoic acid and interleukin 1beta increased MUC4 expression at the gene and protein level in HNPE cells, whereas MUC16 expression was not affected. Unlike retinoic acid and interleukin 1beta, PMA and dexamethasone increased MUC16 expression, whereas they had no significant effect on MUC4 expression. Expression of MUC4 and MUC16 are regulated differently in nasal mucosa. Dexamethasone and PMA are potent mediators for the expression of MUC16 in nasal polyps.

Identification of rice cornichon as a possible cargo receptor for the Golgi-localized sodium transporter OsHKT1;3

PubMed Central

Rosas-Santiago, Paul; Lagunas-Gómez, Daniel; Barkla, Bronwyn J.; Vera-Estrella, Rosario; Lalonde, Sylvie; Jones, Alexander; Frommer, Wolf B.; Zimmermannova, Olga; Sychrová, Hana; Pantoja, Omar

2015-01-01

Membrane proteins are synthesized and folded in the endoplasmic reticulum (ER), and continue their path to their site of residence along the secretory pathway. The COPII system has been identified as a key player for selecting and directing the fate of membrane and secretory cargo proteins. Selection of cargo proteins within the COPII vesicles is achieved by cargo receptors. The cornichon cargo receptor belongs to a conserved protein family found in eukaryotes that has been demonstrated to participate in the selection of integral membrane proteins as cargo for their correct targeting. Here it is demonstrated at the cellular level that rice cornichon OsCNIH1 interacts with OsHKT1;3 and, in yeast cells, enables the expression of the sodium transporter to the Golgi apparatus. Physical and functional HKT–cornichon interactions are confirmed by the mating-based split ubiquitin system, bimolecular fluorescence complementation, and Xenopus oocyte and yeast expression systems. The interaction between the two proteins occurs in the ER of plant cells and their co-expression in oocytes leads to the sequestration of the transporter in the ER. In the yeast cornichon mutant erv14, OsHKT1;3 is mistargeted, preventing the toxic effects of sodium transport in the cell observed in wild-type cells or in the erv14 mutant that co-expressed OsHKT1;3 with either OsCNIH1 or Erv14p. Identification and characterization of rice cornichon as a possible cargo receptor opens up the opportunity to improve our knowledge on membrane protein targeting in plant cells. PMID:25750424

Lipid-Mediated Targeting with Membrane Wrapped Nanoparticles in the Presence of Corona Formation

PubMed Central

Xu, Fangda; Reiser, Michael; Yu, Xinwei; Gummuluru, Suryaram; Wetzler, Lee; Reinhard, Björn M.

2016-01-01

Membrane wrapped nanoparticles represent a versatile platform for utilizing specific lipid-receptor interactions, such as siallyllactose-mediated binding of the ganglioside GM3 to Siglec1 (CD169), for targeting purposes. The membrane wrap around the nanoparticles does not only serve as a matrix to incorporate GM3 as targeting moiety for antigen presenting cells but also offers unique opportunities for constructing a biomimetic surface from lipids with potentially protein repellent properties. We characterize non-specific protein adsorption (corona formation) to membrane wrapped nanoparticles with core diameters of approx. 35 nm and 80 nm and its effect on the GM3-mediated targeting efficacy as function of surface charge through combined in vitro and in vivo studies. The stability and fate of the membrane wrap around the nanoparticles in a simulated biological fluid and after uptake in CD169 expressing antigen presenting cells is experimentally tested. Finally, we demonstrate in hock immunization studies in mice that GM3 decorated membrane wrapped nanoparticles achieve a selective enrichment in the peripheral regions of popliteal lymph nodes that contain high concentrations of CD169 expressing antigen presenting cells. PMID:26720275

Expression of membrane anchored cytokines and B7-1 alters tumor microenvironment and induces protective antitumor immunity in a murine breast cancer model.

PubMed

Bozeman, Erica N; Cimino-Mathews, Ashley; Machiah, Deepa K; Patel, Jaina M; Krishnamoorthy, Arun; Tien, Linda; Shashidharamurthy, Rangaiah; Selvaraj, Periasamy

2013-05-07

Many studies have shown that the systemic administration of cytokines or vaccination with cytokine-secreting tumors augments an antitumor immune response that can result in eradication of tumors. However, these approaches are hampered by the risk of systemic toxicity induced by soluble cytokines. In this study, we have evaluated the efficacy of 4TO7, a highly tumorigenic murine mammary tumor cell line, expressing glycosyl phosphatidylinositol (GPI)-anchored form of cytokine molecules alone or in combination with the costimulatory molecule B7-1 as a model for potential cell or membrane-based breast cancer vaccines. We observed that the GPI-anchored cytokines expressed on the surface of tumor cells greatly reduced the overall tumorigenicity of the 4TO7 tumor cells following direct live cell challenge as evidenced by transient tumor growth and complete regression within 30 days post challenge. Tumors co-expressing B7-1 and GPI-IL-12 grew the least and for the shortest duration, suggesting that this combination of immunostimulatory molecules is most potent. Protective immune responses were also observed following secondary tumor challenge. Further, the 4TO7-B7-1/GPI-IL-2 and 4TO7-B7-1/GPI-IL-12 transfectants were capable of inducing regression of a wild-type tumor growing at a distant site in a concomitant tumor challenge model, suggesting the tumor immunity elicited by the transfectants can act systemically and inhibit the tumor growth at a distant site. Additionally, when used as irradiated whole cell vaccines, 4TO7-B7-1/GPI-IL-12 led to a significant inhibition in tumor growth of day 7 established tumors. Lastly, we observed a significant decrease in the prevalence of myeloid-derived suppressor cells and regulatory T-cells in the tumor microenvironment on day 7 post challenge with 4TO7-B7-1/GPI-IL-12 cells, which provides mechanistic insight into antitumor efficacy of the tumor-cell membrane expressed IL-12. These studies have implications in designing membrane-based therapeutic vaccines with GPI-anchored cytokines for breast cancer. Copyright © 2013 Elsevier Ltd. All rights reserved.

Transcriptomic insights into citrus segment membrane's cell wall components relating to fruit sensory texture.

PubMed

Wang, Xun; Lin, Lijin; Tang, Yi; Xia, Hui; Zhang, Xiancong; Yue, Maolan; Qiu, Xia; Xu, Ke; Wang, Zhihui

2018-04-23

During fresh fruit consumption, sensory texture is one factor that affects the organoleptic qualities. Chemical components of plant cell walls, including pectin, cellulose, hemicellulose and lignin, play central roles in determining the textural qualities. To explore the genes and regulatory pathways involved in fresh citrus' perceived sensory texture, we performed mRNA-seq analyses of the segment membranes of two citrus cultivars, Shiranui and Kiyomi, with different organoleptic textures. Segment membranes were sampled at two developmental stages of citrus fruit, the beginning and end of the expansion period. More than 3000 differentially expressed genes were identified. The gene ontology analysis revealed that more categories were significantly enriched in 'Shiranui' than in 'Kiyomi' at both developmental stages. In total, 108 significantly enriched pathways were obtained, with most belonging to metabolism. A detailed transcriptomic analysis revealed potential critical genes involved in the metabolism of cell wall structures, for example, GAUT4 in pectin synthesis, CESA1, 3 and 6, and SUS4 in cellulose synthesis, CSLC5, XXT1 and XXT2 in hemicellulose synthesis, and CSE in lignin synthesis. Low levels, or no expression, of genes involved in cellulose and hemicellulose, such as CESA4, CESA7, CESA8, IRX9 and IRX14, confirmed that secondary cell walls were negligible or absent in citrus segment membranes. A chemical component analysis of the segment membranes from mature fruit revealed that the pectin, cellulose and lignin contents, and the segment membrane's weight (% of segment) were greater in 'Kiyomi'. Organoleptic quality of citrus is easily overlooked. It is mainly determined by sensory texture perceived in citrus segment membrane properties. We performed mRNA-seq analyses of citrus segment membranes to explore the genes and regulatory pathways involved in fresh citrus' perceived sensory texture. Transcriptomic data showed high repeatability between two independent biological replicates. The expression levels of genes involved in cell wall structure metabolism, including pectin, cellulose, hemicellulose and lignin, were investigated. Meanwhile, chemical component contents of the segment membranes from mature fruit were analyzed. This study provided detailed transcriptional regulatory profiles of different organoleptic citrus qualities and integrated insights into the mechanisms affecting citrus' sensory texture.

Expression and Purification of Rat Glucose Transporter 1 in Pichia pastoris.

PubMed

Venskutonytė, Raminta; Elbing, Karin; Lindkvist-Petersson, Karin

2018-01-01

Large amounts of pure and homogenous protein are a prerequisite for several biochemical and biophysical analyses, and in particular if aiming at resolving the three-dimensional protein structure. Here we describe the production of the rat glucose transporter 1 (GLUT1), a membrane protein facilitating the transport of glucose in cells. The protein is recombinantly expressed in the yeast Pichia pastoris. It is easily maintained and large-scale protein production in shaker flasks, as commonly performed in academic research laboratories, results in relatively high yields of membrane protein. The purification protocol describes all steps needed to obtain a pure and homogenous GLUT1 protein solution, including cell growth, membrane isolation, and chromatographic purification methods.

Elastic modulus affects the growth and differentiation of neural stem cells

PubMed Central

Jiang, Xian-feng; Yang, Kai; Yang, Xiao-qing; Liu, Ying-fu; Cheng, Yuan-chi; Chen, Xu-yi; Tu, Yue

2015-01-01

It remains poorly understood if carrier hardness, elastic modulus, and contact area affect neural stem cell growth and differentiation. Tensile tests show that the elastic moduli of Tiansu and SMI silicone membranes are lower than that of an ordinary dish, while the elastic modulus of SMI silicone membrane is lower than that of Tiansu silicone membrane. Neural stem cells from the cerebral cortex of embryonic day 16 Sprague-Dawley rats were seeded onto ordinary dishes as well as Tiansu silicone membrane and SMI silicone membrane. Light microscopy showed that neural stem cells on all three carriers show improved adherence. After 7 days of differentiation, neuron specific enolase, glial fibrillary acidic protein, and myelin basic protein expression was detected by immunofluorescence. Moreover, flow cytometry revealed a higher rate of neural stem cell differentiation into astrocytes on Tiansu and SMI silicone membranes than on the ordinary dish, which was also higher on the SMI than the Tiansu silicone membrane. These findings confirm that all three cell carrier types have good biocompatibility, while SMI and Tiansu silicone membranes exhibit good mechanical homogenization. Thus, elastic modulus affects neural stem cell differentiation into various nerve cells. Within a certain range, a smaller elastic modulus results in a more obvious trend of cell differentiation into astrocytes. PMID:26604916

Macrosialin, a macrophage-restricted membrane sialoprotein differentially glycosylated in response to inflammatory stimuli [published erratum appears in J Exp Med 1992 Jan 1;175(1):309

PubMed Central

1991-01-01

Rat monoclonal antibody FA/11 has been used to identify macrosialin, a sialoglycoprotein confined to murine mononuclear phagocytes and related cells. Originally identified as a macrophage-associated glycoprotein predominantly localized in intracellular membranes (Smith, M.J., and G.L.E. Koch. 1987. J. Cell Sci. 87:113), the antigen is widely expressed on tissue macrophages, including those in lymphoid areas, and is expressed at low levels on isolated dendritic cells. Immuno- adsorption experiments reported here show that macrosialin is identical to the major 87-115-kD sialoglycoprotein previously identified by lectin blotting in exudate but not resident peritoneal macrophages (Rabinowitz, S., and S. Gordon. 1989. J. Cell Sci. 93:623). Resident peritoneal macrophages express low levels of macrosialin antigen in a glycoform that does not bind 125I wheat germ agglutinin or 125I peanut agglutinin; inflammatory stimuli upregulate expression of this antigen (up to 17-fold), in an alternative glycoform that is detected by these lectins. Pulse-chase experiments reveal a 44-kD core peptide that initially bears high-mannose chains (giving Mr 66 kD) and is subsequently processed to a mature protein of Mr 87-104 kD. Each glycoform contains N-linked glycan, as well as O-linked sugar structures that show alternative processing. Poly-N-acetyllactosamine structures are detected in the exudate cell glycoform only. This new marker for mononuclear phagocytes illustrates two strategies by which macrophages remodel their membranes in response to inflammatory stimuli. Its predominantly intracellular location and restricted cell distribution suggest a possible role in membrane fusion or antigen processing. PMID:1919437

Biophysically inspired model for functionalized nanocarrier adhesion to cell surface: roles of protein expression and mechanical factors

NASA Astrophysics Data System (ADS)

Ramakrishnan, N.; Tourdot, Richard W.; Eckmann, David M.; Ayyaswamy, Portonovo S.; Muzykantov, Vladimir R.; Radhakrishnan, Ravi

2016-06-01

In order to achieve selective targeting of affinity-ligand coated nanoparticles to the target tissue, it is essential to understand the key mechanisms that govern their capture by the target cell. Next-generation pharmacokinetic (PK) models that systematically account for proteomic and mechanical factors can accelerate the design, validation and translation of targeted nanocarriers (NCs) in the clinic. Towards this objective, we have developed a computational model to delineate the roles played by target protein expression and mechanical factors of the target cell membrane in determining the avidity of functionalized NCs to live cells. Model results show quantitative agreement with in vivo experiments when specific and non-specific contributions to NC binding are taken into account. The specific contributions are accounted for through extensive simulations of multivalent receptor-ligand interactions, membrane mechanics and entropic factors such as membrane undulations and receptor translation. The computed NC avidity is strongly dependent on ligand density, receptor expression, bending mechanics of the target cell membrane, as well as entropic factors associated with the membrane and the receptor motion. Our computational model can predict the in vivo targeting levels of the intracellular adhesion molecule-1 (ICAM1)-coated NCs targeted to the lung, heart, kidney, liver and spleen of mouse, when the contributions due to endothelial capture are accounted for. The effect of other cells (such as monocytes, etc.) do not improve the model predictions at steady state. We demonstrate the predictive utility of our model by predicting partitioning coefficients of functionalized NCs in mice and human tissues and report the statistical accuracy of our model predictions under different scenarios.

MDC9, a widely expressed cellular disintegrin containing cytoplasmic SH3 ligand domains

PubMed Central

1996-01-01

Cellular disintegrins are a family of proteins that are related to snake venom integrin ligands and metalloproteases. We have cloned and sequenced the mouse and human homologue of a widely expressed cellular disintegrin, which we have termed MDC9 (for metalloprotease/disintegrin/cysteine-rich protein 9). The deduced mouse and human protein sequences are 82% identical. MDC9 contains several distinct protein domains: a signal sequence is followed by a prodomain and a domain with sequence similarity to snake venom metalloproteases, a disintegrin domain, a cysteine-rich region, an EGF repeat, a membrane anchor, and a cytoplasmic tail. The cytoplasmic tail of MDC9 has two proline-rich sequences which can bind the SH3 domain of Src, and may therefore function as SH3 ligand domains. Western blot analysis shows that MDC9 is an approximately 84-kD glycoprotein in all mouse tissues examined, and in NIH 3T3 fibroblast and C2C12 myoblast mouse cell lines. MDC9 can be both cell surface biotinylated and 125I-labeled in NIH 3T3 mouse fibroblasts, indicating that the protein is present on the plasma membrane. Expression of MDC9 in COS-7 cells yields an 84-kD protein, and immunofluorescence analysis of COS-7 cells expressing MDC9 shows a staining pattern that is consistent with a plasma membrane localization. The apparent molecular mass of 84 kD suggests that MDC9 contains a membrane-anchored metalloprotease and disintegrin domain. We propose that MDC9 might function as a membrane-anchored integrin ligand or metalloprotease, or that MDC9 may combine both activities in one protein. PMID:8647900

A novel closed cell culture device for fabrication of corneal epithelial cell sheets.

PubMed

Nakajima, Ryota; Kobayashi, Toyoshige; Moriya, Noboru; Mizutani, Manabu; Kan, Kazutoshi; Nozaki, Takayuki; Saitoh, Kazuo; Yamato, Masayuki; Okano, Teruo; Takeda, Shizu

2015-11-01

Automation technology for cell sheet-based tissue engineering would need to optimize the cell sheet fabrication process, stabilize cell sheet quality and reduce biological contamination risks. Biological contamination must be avoided in clinical settings. A closed culture system provides a solution for this. In the present study, we developed a closed culture device called a cell cartridge, to be used in a closed cell culture system for fabricating corneal epithelial cell sheets. Rabbit limbal epithelial cells were cultured on the surface of a porous membrane with 3T3 feeder cells, which are separate from the epithelial cells in the cell cartridges and in the cell-culture inserts as a control. To fabricate the stratified cell sheets, five different thicknesses of the membranes which were welded to the cell cartridge, were examined. Multilayered corneal epithelial cell sheets were fabricated in cell cartridges that were welded to a 25 µm-thick gas-permeable membrane, which was similar to the results with the cell-culture inserts. However, stratification of corneal epithelial cell sheets did not occur with cell cartridges that were welded to 100-300 µm-thick gas-permeable membranes. The fabricated cell sheets were evaluated by histological analyses to examine the expression of corneal epithelial-specific markers. Immunohistochemical analyses showed that a putative stem cell marker, p63, a corneal epithelial differentiation maker, CK3, and a barrier function marker, Claudin-1, were expressed in the appropriate position in the cell sheets. These results suggest that the cell cartridge is effective for fabricating corneal epithelial cell sheets. Copyright © 2012 John Wiley & Sons, Ltd.

Does Increased Expression of the Plasma Membrane Calcium-ATPase Isoform 2 Confer Resistance to Apoptosis on Breast Cancer Cells?

DTIC Science & Technology

2008-09-01

T47D control cells with the highest sustained levels of intracellular calcium in the  live   cell   imaging  experiments (Figure 9). Membrane blebbing is a...classic hallmark, and early indicator of apoptosis. No  membrane blebbing was observed in T47D/PMCA2 cells during the  live   cell   imaging  studies.     10

Cell recruitment by amnion chorion grafts promotes neovascularization.

PubMed

Maan, Zeshaan N; Rennert, Robert C; Koob, Thomas J; Januszyk, Michael; Li, William W; Gurtner, Geoffrey C

2015-02-01

Nonhealing wounds are a significant health burden. Stem and progenitor cells can accelerate wound repair and regeneration. Human amniotic membrane has demonstrated efficacy in promoting wound healing, though the underlying mechanisms remain unknown. A dehydrated human amnion chorion membrane (dHACM) was tested for its ability to recruit hematopoietic progenitor cells to a surgically implanted graft in a murine model of cutaneous ischemia. dHACM was subcutaneously implanted under elevated skin (ischemic stimulus) in either wild-type mice or mice surgically parabiosed to green fluorescent protein (GFP) + reporter mice. A control acellular dermal matrix, elevated skin without an implant, and normal unwounded skin were used as controls. Wound tissue was harvested and processed for histology and flow cytometric analysis. Implanted dHACMs recruited significantly more progenitor cells compared with controls (*P < 0.05) and displayed in vivo SDF-1 expression with incorporation of CD34 + progenitor cells within the matrix. Parabiosis modeling confirmed the circulatory origin of recruited cells, which coexpressed progenitor cell markers and were localized to foci of neovascularization within implanted matrices. In summary, dHACM effectively recruits circulating progenitor cells, likely because of stromal derived factor 1 (SDF-1) expression. The recruited cells express markers of "stemness" and localize to sites of neovascularization, providing a partial mechanism for the clinical efficacy of human amniotic membrane in the treatment of chronic wounds. Copyright © 2015 Elsevier Inc. All rights reserved.

Cell recruitment by amnion chorion grafts promotes neovascularization

PubMed Central

Koob, Thomas J.; Januszyk, Michael; Li, William W.; Gurtner, Geoffrey C.

2015-01-01

Background Nonhealing wounds are a significant health burden. Stem and progenitor cells can accelerate wound repair and regeneration. Human amniotic membrane has demonstrated efficacy in promoting wound healing, though the underlying mechanisms remain unknown. A dehydrated human amnion chorion membrane (dHACM) was tested for its ability to recruit hematopoietic progenitor cells to a surgically implanted graft in a murine model of cutaneous ischemia. Methods dHACM was subcutaneously implanted under elevated skin (ischemic stimulus) in either wild-type mice or mice surgically parabiosed to green fluorescent protein (GFP) + reporter mice. A control acellular dermal matrix, elevated skin without an implant, and normal unwounded skin were used as controls. Wound tissue was harvested and processed for histology and flow cytometric analysis. Results Implanted dHACMs recruited significantly more progenitor cells compared with controls (*P < 0.05) and displayed in vivo SDF-1 expression with incorporation of CD34 + progenitor cells within the matrix. Parabiosis modeling confirmed the circulatory origin of recruited cells, which coexpressed progenitor cell markers and were localized to foci of neovascularization within implanted matrices. Conclusions In summary, dHACM effectively recruits circulating progenitor cells, likely because of stromal derived factor 1 (SDF-1) expression. The recruited cells express markers of “stemness” and localize to sites of neovascularization, providing a partial mechanism for the clinical efficacy of human amniotic membrane in the treatment of chronic wounds. PMID:25266600

Association of Shiga toxin glycosphingolipid receptors with membrane microdomains of toxin-sensitive lymphoid and myeloid cells[S

PubMed Central

Kouzel, Ivan U.; Pohlentz, Gottfried; Storck, Wiebke; Radamm, Lena; Hoffmann, Petra; Bielaszewska, Martina; Bauwens, Andreas; Cichon, Christoph; Schmidt, M. Alexander; Mormann, Michael; Karch, Helge; Müthing, Johannes

2013-01-01

Glycosphingolipids (GSLs) of the globo-series constitute specific receptors for Shiga toxins (Stxs) released by certain types of pathogenic Escherichia coli strains. Stx-loaded leukocytes may act as transporter cells in the blood and transfer the toxin to endothelial target cells. Therefore, we performed a thorough investigation on the expression of globo-series GSLs in serum-free cultivated Raji and Jurkat cells, representing B- and T-lymphocyte descendants, respectively, as well as THP-1 and HL-60 cells of the monocyte and granulocyte lineage, respectively. The presence of Stx-receptors in GSL preparations of Raji and THP-1 cells and the absence in Jurkat and HL-60 cells revealed high compliance of solid-phase immunodetection assays with the expression profiles of receptor-related glycosyltransferases, performed by qRT-PCR analysis, and Stx2-caused cellular damage. Canonical microdomain association of Stx GSL receptors, sphingomyelin, and cholesterol in membranes of Raji and THP-1 cells was assessed by comparative analysis of detergent-resistant membrane (DRM) and nonDRM fractions obtained by density gradient centrifugation and showed high correlation based on nonparametric statistical analysis. Our comprehensive study on the expression of Stx-receptors and their subcellular distribution provides the basis for exploring the functional role of lipid raft-associated Stx-receptors in cells of leukocyte origin. PMID:23248329

Pepper pathogenesis-related protein 4c is a plasma membrane-localized cysteine protease inhibitor that is required for plant cell death and defense signaling.

PubMed

Kim, Nak Hyun; Hwang, Byung Kook

2015-01-01

Xanthomonas campestris pv. vesicatoria (Xcv) type III effector AvrBsT triggers programmed cell death (PCD) and activates the hypersensitive response (HR) in plants. Here, we isolated and identified the plasma membrane localized pathogenesis-related (PR) protein 4c gene (CaPR4c) from pepper (Capsicum annuum) leaves undergoing AvrBsT-triggered HR cell death. CaPR4c encodes a protein with a signal peptide and a Barwin domain. Recombinant CaPR4c protein expressed in Escherichia coli exhibited cysteine protease-inhibitor activity and ribonuclease (RNase) activity. Subcellular localization analyses revealed that CaPR4c localized to the plasma membrane in plant cells. CaPR4c expression was rapidly and specifically induced by avirulent Xcv (avrBsT) infection. Transient expression of CaPR4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H2 O2 and significant induction of some defense-response genes. Deletion of the signal peptide from CaPR4c abolished the induction of HR cell death, indicating a requirement for plasma membrane localization of CaPR4c for HR cell death. CaPR4c silencing in pepper disrupted both basal and AvrBsT-triggered resistance responses, and enabled Xcv proliferation in infected leaves. H2 O2 accumulation, cell-death induction, and defense-response gene expression were distinctly reduced in CaPR4c-silenced pepper. CaPR4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis. These results collectively suggest that CaPR4c plays an important role in plant cell death and defense signaling. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Plasma membrane repair and cellular damage control: the annexin survival kit.

PubMed

Draeger, Annette; Monastyrskaya, Katia; Babiychuk, Eduard B

2011-03-15

Plasmalemmal injury is a frequent event in the life of a cell. Physical disruption of the plasma membrane is common in cells that operate under conditions of mechanical stress. The permeability barrier can also be breached by chemical means: pathogens gain access to host cells by secreting pore-forming toxins and phospholipases, and the host's own immune system employs pore-forming proteins to eliminate both pathogens and the pathogen-invaded cells. In all cases, the influx of extracellular Ca(2+) is being sensed and interpreted as an "immediate danger" signal. Various Ca(2+)-dependent mechanisms are employed to enable plasma membrane repair. Extensively damaged regions of the plasma membrane can be patched with internal membranes delivered to the cell surface by exocytosis. Nucleated cells are capable of resealing their injured plasmalemma by endocytosis of the permeabilized site. Likewise, the shedding of membrane microparticles is thought to be involved in the physical elimination of pores. Membrane blebbing is a further damage-control mechanism, which is triggered after initial attempts at plasmalemmal resealing have failed. The members of the annexin protein family are ubiquitously expressed and function as intracellular Ca(2+) sensors. Most cells contain multiple annexins, which interact with distinct plasma membrane regions promoting membrane segregation, membrane fusion and--in combination with their individual Ca(2+)-sensitivity--allow spatially confined, graded responses to membrane injury. Copyright © 2011 Elsevier Inc. All rights reserved.

Amniotic membrane traps and induces apoptosis of inflammatory cells in ocular surface chemical burn

PubMed Central

Liu, Ting; Zhai, Hualei; Xu, Yuanyuan; Dong, Yanling; Sun, Yajie; Zang, Xinjie

2012-01-01

Purpose Severe chemical burns can cause necrosis of ocular surface tissues following the infiltration of inflammatory cells. It has been shown that amniotic membrane transplantation (AMT) is an effective treatment for severe chemical burns, but the phenotypes of cells that infiltrate the amniotic membrane and the clinical significance of these cellular infiltrations have not previously been reported. The present work studies the inflammation cell traps and apoptosis inducing roles of the amniotic membrane after AMT in patients with acute chemical burns. Methods A total of 30 patients with acute alkaline burns were classified as having either moderate or severe burns. In all participants, AMT was performed within one week of his/her injury. After 7–9 days, the transplanted amniotic membranes were removed. Histopathological and immunohistochemical techniques were used for the examination and detection of infiltrating cells, and tests for the expression of CD (cluster of differentiation)15, CD68, CD3, CD20, CD57, CD31, CD147, and CD95 (Fas) were performed. A TUNEL (TdT-mediated dUTP nick end labeling) assay was used to confirm apoptosis of the infiltrating cells. Three patients with herpes simplex-induced keratitis who had undergone AMT to treat persistent epithelium defects were used as a control group. Amniotic membrane before transplantation was used as another control. Results After amniotic membrane transplantation, the number of infiltrating cells in patients with severe burns was significantly higher than in patients with moderate burns or in control patients (p<0.05). Among the severe burns patients, CD15 and CD68 were widely expressed in the infiltrating cells, and CD3, CD20, and CD57 were only found in a small number of cells. Occasionally, CD31-positive cells were found in the amniotic membranes. More cells that were CD147, Fas, and TUNEL positive were found in patients with severe burns than in patients with moderate burns or in control patients. Conclusions Neutrophils and macrophages were the main cells that had infiltrated into the amniotic membrane during the acute phase of healing from a chemical burns. AMT can trap different inflammatory cells and induce apoptosis of inflammatory cells in acute ocular chemical burns. PMID:22876141

Thrombomodulin-mediated cell adhesion: involvement of its lectin-like domain.

PubMed

Huang, Huey-Chun; Shi, Guey-Yueh; Jiang, Shinn-Jong; Shi, Chung-Sheng; Wu, Chun-Mei; Yang, Hsi-Yuan; Wu, Hua-Lin

2003-11-21

Thrombomodulin (TM) is an integral membrane glycoprotein that is a potent anticoagulant factor. TM may also possess functions distinct from its anticoagulant activity. Here the influence of TM on cell adhesion was studied in TM-negative melanoma A2058 cells transfected with green fluorescent protein-tagged TM (TMG) or lectin domain-deleted TM (TMG(DeltaL)). Confocal microscopy demonstrated that both TMG and TMG(DeltaL) were distributed in the plasma membrane. TMG-expressed cells grew as closely clustered colonies, with TM localized prominently in the intercellular boundaries. TMG(DeltaL)-expressed cells grew singly. Overexpression of TMG, but not TMG(DeltaL), decreased monolayer permeability in vitro and tumor growth in vivo. The cell-to-cell adhesion in TMG-expressed cells was Ca2+-dependent and was inhibited by monoclonal antibody against the lectin-like domain of TM. The effects of TM-mediated cell adhesion were abolished by the addition of mannose, chondroitin sulfate A, or chondroitin sulfate C. In addition, anti-lectin-like domain antibody disrupted the close clustering of the endogenous TM-expressed keratinocyte HaCaT cell line derived from normal human epidermis. Double-labeling immunofluorescence staining revealed similar distributions of TM and actin filament in the cortex region of the TMG-expressed cells. Thus, TM can function as a Ca2+-dependent cell-to-cell adhesion molecule. Binding of specific carbohydrates to the lectin-like domain is essential for this specific function.

Abnormal expression of p27kip1 protein in levator ani muscle of aging women with pelvic floor disorders – a relationship to the cellular differentiation and degeneration

PubMed Central

Bukovsky, Antonin; Copas, Pleas; Caudle, Michael R; Cekanova, Maria; Dassanayake, Tamara; Asbury, Bridgett; Van Meter, Stuart E; Elder, Robert F; Brown, Jeffrey B; Cross, Stephanie B

2001-01-01

Background Pelvic floor disorders affect almost 50% of aging women. An important role in the pelvic floor support belongs to the levator ani muscle. The p27/kip1 (p27) protein, multifunctional cyclin-dependent kinase inhibitor, shows changing expression in differentiating skeletal muscle cells during development, and relatively high levels of p27 RNA were detected in the normal human skeletal muscles. Methods Biopsy samples of levator ani muscle were obtained from 22 symptomatic patients with stress urinary incontinence, pelvic organ prolapse, and overlaps (age range 38–74), and nine asymptomatic women (age 31–49). Cryostat sections were investigated for p27 protein expression and type I (slow twitch) and type II (fast twitch) fibers. Results All fibers exhibited strong plasma membrane (and nuclear) p27 protein expression. cytoplasmic p27 expression was virtually absent in asymptomatic women. In perimenopausal symptomatic patients (ages 38–55), muscle fibers showed hypertrophy and moderate cytoplasmic p27 staining accompanied by diminution of type II fibers. Older symptomatic patients (ages 57–74) showed cytoplasmic p27 overexpression accompanied by shrinking, cytoplasmic vacuolization and fragmentation of muscle cells. The plasma membrane and cytoplasmic p27 expression was not unique to the muscle cells. Under certain circumstances, it was also detected in other cell types (epithelium of ectocervix and luteal cells). Conclusions This is the first report on the unusual (plasma membrane and cytoplasmic) expression of p27 protein in normal and abnormal human striated muscle cells in vivo. Our data indicate that pelvic floor disorders are in perimenopausal patients associated with an appearance of moderate cytoplasmic p27 expression, accompanying hypertrophy and transition of type II into type I fibers. The patients in advanced postmenopause show shrinking and fragmentation of muscle fibers associated with strong cytoplasmic p27 expression. PMID:11696252

Arachidonic Acid-Induced Expression of the Organic Solute and Steroid Transporter-beta (Ost-beta) in a Cartilaginous Fish Cell Line

PubMed Central

Hwang, Jae-Ho; Parton, Angela; Czechanski, Anne; Ballatori, Nazzareno; Barnes, David

2008-01-01

The organic solute and steroid transporter (OST/Ost) is a unique membrane transport protein heterodimer composed of subunits designated alpha and beta, that transports conjugated steroids and prostaglandin E2 across the plasma membrane. Ost was first identified in the liver of the cartilaginous fish Leucoraja erinacea, the little skate, and subsequently was found in many other species, including humans and rodents. The present study describes the isolation of a new cell line, LEE-1, derived from an early embryo of L. erinacea, and characterizes the expression of Ost in these cells. The mRNA size and amino acid sequence of Ost-beta in LEE-1 was identical to that previously reported for Ost-beta from skate liver, and the primary structure was identical to that of the spiny dogfish shark (Squalus acanthias) with the exception of a single amino acid. Ost-beta was found both on the plasma membrane and intracellularly in LEE-1 cells, consistent with its localization in other cell types. Interestingly, arachidonic acid, the precursor to eiconsanoids, strongly induced Ost-beta expression in LEE-1 cells and a lipid mixture containing arachidonic acid also induced Ost-alpha. Overall, the present study describes the isolation of a novel marine cell line, and shows that this cell line expresses relatively high levels of Ost when cultured in the presence of arachidonic acid. Although the function of this transport protein in embryo-derived cells is unknown, it may play a role in the disposition of eicosanoids or steroid-derived molecules. PMID:18407792

Activation of syntaxin 1C, an alternative splice variant of HPC-1/syntaxin 1A, by phorbol 12-myristate 13-acetate (PMA) suppresses glucose transport into astroglioma cells via the glucose transporter-1 (GLUT-1).

PubMed

Nakayama, Takahiro; Mikoshiba, Katsuhiko; Yamamori, Tetsuo; Akagawa, Kimio

2004-05-28

Syntaxin 1C is an alternative splice variant lacking the transmembrane domain of HPC-1/syntaxin 1A. We found previously that syntaxin 1C is expressed as a soluble protein in human astroglioma (T98G) cells, and syntaxin 1C expression is enhanced by stimulation with phorbol 12-myristate 13-acetate (PMA). However, the physiological function of syntaxin 1C is not known. In this study, we examined the relationship between syntaxin 1C and glucose transport. First, we discovered that glucose transporter-1 (GLUT-1) was the primary isoform in T98G cells. Second, we demonstrated that glucose uptake in T98G cells was suppressed following an increase in endogenous syntaxin 1C after stimulation with PMA, which did not alter the expression levels of other plasma membrane syntaxins. We further examined glucose uptake and intracellular localization of GLUT-1 in cells that overexpressed exogenous syntaxin 1C; glucose uptake via GLUT-1 was inhibited without affecting sodium-dependent glucose transport. The value of Vmax for the dose-dependent uptake of glucose was reduced in syntaxin 1C-expressing cells, whereas there was no change in Km. Immunofluorescence studies revealed a reduction in the amount of GLUT-1 in the plasma membrane in cells that expressed syntaxin 1C. Based on these results, we postulate that syntaxin 1C regulates glucose transport in astroglioma cells by changing the intracellular trafficking of GLUT-1. This is the first report to indicate that a syntaxin isoform that lacks a transmembrane domain can regulate the intracellular transport of a plasma membrane protein.

Membrane expression of MRP-1, but not MRP-1 splicing or Pgp expression, predicts survival in patients with ESFT.

PubMed

Roundhill, E; Burchill, S

2013-07-09

Primary Ewing's sarcoma family of tumours (ESFTs) may respond to chemotherapy, although many patients experience subsequent disease recurrence and relapse. The survival of ESFT cells following chemotherapy has been attributed to the development of resistant disease, possibly through the expression of ABC transporter proteins. MRP-1 and Pgp mRNA and protein expression in primary ESFTs was determined by quantitative reverse-transcriptase PCR (RT-qPCR) and immunohistochemistry, respectively, and alternative splicing of MRP-1 by RT-PCR. We observed MRP-1 protein expression in 92% (43 out of 47) of primary ESFTs, and cell membrane MRP-1 was highly predictive of both overall survival (P<0.0001) and event-free survival (P<0.0001). Alternative splicing of MRP-1 was detected in primary ESFTs, although the pattern of splicing variants was not predictive of patient outcome, with the exception of loss of exon 9 in six patients, which predicted relapse (P=0.041). Pgp protein was detected in 6% (38 out of 44) of primary ESFTs and was not associated with patient survival. For the first time we have established that cell membrane expression of MRP-1 or loss of exon 9 is predictive of outcome but not the number of splicing events or expression of Pgp, and both may be valuable factors for the stratification of patients for more intensive therapy.

KCC2a expression in a human fetal lens epithelial cell line.

PubMed

Lauf, Peter K; Di Fulvio, Mauricio; Srivastava, Vinita; Sharma, Neelima; Adragna, Norma C

2012-01-01

The fetal human lens epithelial cell (LEC) line (FHL124) possesses all four K(+)Cl(-) (KCC) cotransporter isoforms, KCC1-4, despite KCC2 being typically considered a neuronal isoform. Since at least two spliced variants, KCC2a and KCC2b, are co-expressed in cells of the central nervous system, this study sought to define the KCC2 expression profile in FHL124 cells. KCC2a, but not KCC2b transcripts were detected by reverse transcriptase polymerase chain reaction (RT-PCR). Proteins of molecular weights ranging from 95 to 135 kDa were found by Western blotting using non-variant specific anti-KCC2 antibodies directed against two different regions of the KCC2 proteins, and by biotinylation suggesting membrane expression. Immunofluorescence revealed membrane and punctate cytoplasmic staining for KCC2. Low levels of cytosolic αA and αB crystallines, and neuron-specific enolase were also detected contrasting with the strong membrane immunofluorescence staining for the Na/K ATPase α1 subunit. Since the lack of neuron-specific expression of the KCC2b variant in non-neuronal tissues has been proposed under control of a neuron-restrictive silencing element in the KCC2 gene, we hypothesize that this control may be lifted for the KCC2a variant in the FHL124 epithelial cell culture, a non-neuronal tissue of ectodermal origin. Copyright © 2012 S. Karger AG, Basel.

Globotriaosylceramide induces lysosomal degradation of endothelial KCa3.1 in fabry disease.

PubMed

Choi, Shinkyu; Kim, Ji Aee; Na, Hye-Young; Cho, Sung-Eun; Park, Seonghee; Jung, Sung-Chul; Suh, Suk Hyo

2014-01-01

Globotriaosylceramide (Gb3) induces KCa3.1 downregulation in Fabry disease (FD). We investigated whether Gb3 induces KCa3.1 endocytosis and degradation. KCa3.1, especially plasma membrane-localized KCa3.1, was downregulated in both Gb3-treated mouse aortic endothelial cells (MAECs) and human umbilical vein endothelial cells. Gb3-induced KCa3.1 downregulation was prevented by lysosomal inhibitors but not by a proteosomal inhibitor. Endoplasmic reticulum stress-inducing agents did not induce KCa3.1 downregulation. Gb3 upregulated the protein levels of early endosome antigen 1 and lysosomal-associated membrane protein 2 in MAECs. Compared with MAECs from age-matched wild-type mice, those from aged α-galactosidase A (Gla)-knockout mice, an animal model of FD, showed downregulated KCa3.1 expression and upregulated early endosome antigen 1 and lysosomal-associated membrane protein 2 expression. In contrast, no significant difference was found in early endosome antigen 1 and lysosomal-associated membrane protein 2 expression between young Gla-knockout and wild-type MAECs. In aged Gla-knockout MAECs, clathrin was translocated close to the cell border and clathrin knockdown recovered KCa3.1 expression. Rab5, an effector of early endosome antigen 1, was upregulated, and Rab5 knockdown restored KCa3.1 expression, the current, and endothelium-dependent relaxation. -Gb3 accelerates the endocytosis and lysosomal degradation of endothelial KCa3.1 via a clathrin-dependent process, leading to endothelial dysfunction in FD.

The changes of potassium currents in RCS rat Müller cell during retinal degeneration.

PubMed

Zhao, TongTao; Li, YaoChen; Weng, ChuanHuang; Yin, ZhengQin

2012-01-03

Müller cells are the principal glial cells expressing membrane-bound potassium channel and predominantly mediating the homeostatic regulation of extracellular K+ produced by neuronal activity in retina. It's well known that Müller cells can be activated in many pathological conditions, but little is known about the change of potassium currents of Müller cells during the progression of retinitis pigmentosa. Herein, the Royal College of Surgeons rats (RCS rat) were employed to investigate some phenotypic and functional changes of Müller cells during retinal degeneration such as the expression of Kir4.1, membrane properties and K+ channel currents by using immunohistochemistry, RT-PCR, western blot and whole-cell patch clamping respectively. Compared with Müller cells in control retina, increased glutamine synthetase (GS) mRNA levels were seen at P30 and P60, and then decreased gradually in RCS rat retina. Morphologically, Müller cells showed significant hypertrophy and proliferation after p60. The increased expression of intermediate filament, glial fibrillary acidic protein (GFAP) and vimentin began at P30 and reached a peak at p60. Kir4.1 channels presented a peak expression at P30. Concomitantly, K(+) currents of Müller cells increased at P30 and decreased at P90 significantly. We concluded that retinal Müller cells of RCS rats underwent an activation initiated by the onset of retinal degeneration before p60 and then an obvious reactive gliosis, which led the basic membrane properties to suffer marked changes, and caused the Kir4.1 channels of Müller cells to occur a clear functional shift, even lose their normal electrophysiological properties. This process aggravates the impairment caused by the initial photoreceptor degeneration. Copyright © 2011 Elsevier B.V. All rights reserved.

Localization of aPKC lambda/iota and its interacting protein, Lgl2, is significantly associated with lung adenocarcinoma progression.

PubMed

Imamura, Naoko; Horikoshi, Yosuke; Matsuzaki, Tomohiko; Toriumi, Kentaro; Kitatani, Kanae; Ogura, Go; Masuda, Ryota; Nakamura, Naoya; Takekoshi, Susumu; Iwazaki, Masayuki

2013-12-20

Atypical protein kinase C lambda/iota (aPKC λ/ι) is expressed in several human cancers; however, the correlation between aPKC λ/ι localization and cancer progression in human lung adenocarcinoma (LAC) remains to be clarified. We found that patients with a high level of aPKC λ/ι expression in LAC had significantly shorter overall survival than those with a low level of aPKC λ/ι expression. In addition, localization of aPKC λ/ι in the apical membrane or at the cell-cell contact was associated with both lymphatic invasion and metastasis. The intercellular adhesion molecule, E-cadherin, was decreased in LACs with highly expressed aPKC λ/ι at the invasion site of tumor cells. This result suggested that the expression levels of aPKC λ/ι and E-cadherin reflect the progression of LAC. On double-immunohistochemical analysis, aPKC λ/ι and Lgl2, a protein that interacts with aPKC λ/ι, were co-localized within LACs. Furthermore, we found that Lgl2 bound the aPKC λ/ι-Par6 complex in tumor tissue by immune-cosedimentation analysis. Apical membrane localization of Lgl2 was correlated with lymphatic invasion and lymph node metastasis. These results thus indicate that aPKC λ/ι expression is altered upon the progression of LAC. This is also the first evidence to show aPKC λ/ι overexpression in LAC and demonstrates that aPKC λ/ι localization at the apical membrane or cell-cell contact is associated with lymphatic invasion and metastasis of the tumor.

Regulation of membrane-associated mucins in the human corneal epithelial cells by dexamethasone.

PubMed

Seo, Kyoung Yul; Chung, So-Hyang; Lee, Joon H; Park, Mi Young; Kim, Eung Kweon

2007-07-01

To study the influence of dexamethasone on membrane-associated mucins produced by human corneal epithelial cells. Human corneal epithelial cells were cultured in medium supplemented with various concentrations of dexamethasone (ranging from 10 to 10 M). Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis using monoclonal antibodies specific for human MUC1 (HMFG-1), MUC4 (1G8), and MUC16 (OC125) were performed to evaluate the effect of dexamethasone on membrane-associated mucin expression. The effect of glucocorticoid receptor antagonist (RU38486) on dexamethasone-induced mucin expression was estimated. RT-PCR revealed that MUC1 and MUC16 gene expression were upregulated 48 hours after addition of dexamethasone and that MUC4 gene expression was downregulated in the same condition. Western blot analysis showed that MUC1 and MUC16 proteins were increased after addition of dexamethasone. However, MUC4 was not detected by anti-MUC4 monoclonal antibody (1G8) for ASGP-2 under our conditions. Treatment with RU38486 inhibited the changes of MUC1, MUC4, and MUC16 by dexamethasone; thus, the effect of dexamethasone on mucin expression is mediated by glucocorticoid receptors. This study shows that MUC1, MUC4, and MUC16 are regulated differently by dexamethasone in human corneal epithelial cells. External application of dexamethasone might affect the precorneal mucin.

Arabidopsis synaptotagmin 1 is required for the maintenance of plasma membrane integrity and cell viability.

PubMed

Schapire, Arnaldo L; Voigt, Boris; Jasik, Jan; Rosado, Abel; Lopez-Cobollo, Rosa; Menzel, Diedrik; Salinas, Julio; Mancuso, Stefano; Valpuesta, Victoriano; Baluska, Frantisek; Botella, Miguel A

2008-12-01

Plasma membrane repair in animal cells uses synaptotagmin 7, a Ca(2+)-activated membrane fusion protein that mediates delivery of intracellular membranes to wound sites by a mechanism resembling neuronal Ca(2+)-regulated exocytosis. Here, we show that loss of function of the homologous Arabidopsis thaliana Synaptotagmin 1 protein (SYT1) reduces the viability of cells as a consequence of a decrease in the integrity of the plasma membrane. This reduced integrity is enhanced in the syt1-2 null mutant in conditions of osmotic stress likely caused by a defective plasma membrane repair. Consistent with a role in plasma membrane repair, SYT1 is ubiquitously expressed, is located at the plasma membrane, and shares all domains characteristic of animal synaptotagmins (i.e., an N terminus-transmembrane domain and a cytoplasmic region containing two C2 domains with phospholipid binding activities). Our analyses support that membrane trafficking mediated by SYT1 is important for plasma membrane integrity and plant fitness.

Tumor dormancy and cell signaling: anti-mu-induced apoptosis in human B-lymphoma cells is not caused by an APO-1-APO-1 ligand interaction.

PubMed Central

Racila, E; Hsueh, R; Marches, R; Tucker, T F; Krammer, P H; Scheuermann, R H; Uhr, J W

1996-01-01

Signal transduction initiated by crosslinking of antigen-specific receptors on T- and B-lymphoma cells induces apoptosis. In T-lymphoma cells, such crosslinking results in upregulation of the APO-1 ligand, which then interacts with induced or constitutively expressed APO-1, thereby triggering apoptosis. Here we show that crosslinking the membrane immunoglobulin on human lymphoma cells (Daudi) (that constitutively express APO-1) does not induce synthesis of APO-1 ligand. Further, a noncytotoxic fragment of anti-APO-1 antibody that blocks T-cell-receptor-mediated apoptosis in T-lymphoma cells does not block anti-mu-induced apoptosis. Hence, in B-lymphoma cells, apoptosis induced by signaling via membrane IgM is not mediated by the APO-1 ligand. Images Fig. 2 Fig. 3 PMID:8700902

Cell-Free Translation of Integral Membrane Proteins into Unilamelar Liposomes

PubMed Central

Goren, Michael A.; Nozawa, Akira; Makino, Shin-ichi; Wrobel, Russell L.; Fox, Brian G.

2018-01-01

Wheat germ cell-free translation is shown to be an effective method to produce integral membrane proteins in the presence of unilamelar liposomes. In this chapter, we describe the expression vectors, preparation of mRNA, two types of cell-free translation reactions performed in the presence of liposomes, a simple and highly efficient purification of intact proteoliposomes using density gradient ultracentrifugation, and some of the types of characterization studies that are facilitated by this facile preparative approach. The in vitro transfer of newly translated, membrane proteins into liposomes compatible with direct measurements of their catalytic function is contrasted with existing approaches to extract membrane proteins from biological membranes using detergents and subsequently transfer them back to liposomes for functional studies. PMID:19892197

Glut-1 translocation in FRTL-5 thyroid cells: role of phosphatidylinositol 3-kinase and N-glycosylation.

PubMed

Samih, N; Hovsepian, S; Aouani, A; Lombardo, D; Fayet, G

2000-11-01

It was previously demonstrated that insulin or TSH treatment of FRTL-5 cells resulted in an elevation of glucose transport and in an increase of cell surface expression of the glucose transporter Glut-1. However, the signaling mechanisms leading to the insulin or TSH-induced increase in the cell surface expression of Glut-1 were not investigated. In the present study, we demonstrated that wortmannin and LY294002, two specific inhibitors of phosphatidylinositol 3-kinase (PI3-kinase), interfere both in the signaling pathways of insulin and TSH leading to glucose consumption enhancement and Glut-1 translocation. Two hours after insulin treatment, TSH or cAMP analog (Bu)2cAMP stimulation, glucose transport was increased and most of the intracellular Glut-1 pool was translocated to plasma membranes. Wortmannin or LY294002 blocked the insulin, (Bu)2cAMP, and the TSH-induced translocation of Glut-1. Wortmannin or LY294002 alone did not alter the basal ratio between intracellular and cell surface Glut-1 molecules. These results suggest that in FRTL-5 cells wortmannin and LY294002 inhibited the insulin, (Bu)2cAMP and TSH events leading to Glut-1 translocation from an intracellular compartment to the plasma membrane. Likewise, (Bu)2cAMP effects on glucose transport and Glut-1 translocation to plasma membrane were repressed by PI3-kinase inhibitors but not by the protein kinase A (PKA) inhibitor H89. We suggest that (Bu)2cAMP stimulates Glut-1 translocation to plasma membrane through PI3-kinase-dependent and PKA-independent signaling pathways. To further elucidate mechanisms that regulate the translocation of Glut-1 to cell membrane, we extended this study to the role played by the N-glycosylation in the translocation and in the biological activity of Glut-1 in FRTL-5 cells. For this purpose we used tunicamycin, an inhibitor of the N-glycosylation. Our experiments with tunicamycin clearly showed that both the glycosylated and unglycosylated forms of the transporter reached the cell surface. Likewise, a decrease in glucose consumption (-50%) after treatment of cells with tunicamycin was accompanied by a decrease (-70% vs. control) in the membrane expression of a 50-kDa form of Glut-1 and an increase in its unglycosylated 41-kDa form. These results suggest that carbohydrate moiety is essential for the biological activity of glucose transport but is not required for the translocation of Glut-1 from the intracellular membrane pool to the plasma membrane.

Characterization of AgMaT2, a Plasma Membrane Mannitol Transporter from Celery, Expressed in Phloem Cells, Including Phloem Parenchyma Cells[OA

PubMed Central

Juchaux-Cachau, Marjorie; Landouar-Arsivaud, Lucie; Pichaut, Jean-Philippe; Campion, Claire; Porcheron, Benoit; Jeauffre, Julien; Noiraud-Romy, Nathalie; Simoneau, Philippe; Maurousset, Laurence; Lemoine, Rémi

2007-01-01

A second mannitol transporter, AgMaT2, was identified in celery (Apium graveolens L. var. dulce), a species that synthesizes and transports mannitol. This transporter was successfully expressed in two different heterologous expression systems: baker's yeast (Saccharomyces cerevisiae) cells and tobacco (Nicotiana tabacum) plants (a non-mannitol-producing species). Data indicated that AgMaT2 works as an H+/mannitol cotransporter with a weak selectivity toward other polyol molecules. When expressed in tobacco, AgMaT2 decreased the sensitivity to the mannitol-secreting pathogenic fungi Alternaria longipes, suggesting a role for polyol transporters in defense mechanisms. In celery, in situ hybridization showed that AgMaT2 was expressed in the phloem of leaflets, petioles from young and mature leaves, floral stems, and roots. In the phloem of petioles and leaflets, AgMaT2, as localized with specific antibodies, was present in the plasma membrane of three ontologically related cell types: sieve elements, companion cells, and phloem parenchyma cells. These new data are discussed in relation to the physiological role of AgMaT2 in regulating mannitol fluxes in celery petioles. PMID:17631523

Expression of DNAJB12 or DNAJB14 Causes Coordinate Invasion of the Nucleus by Membranes Associated with a Novel Nuclear Pore Structure

PubMed Central

Goodwin, Edward C.; Motamedi, Nasim; Lipovsky, Alex; Fernández-Busnadiego, Rubén; DiMaio, Daniel

2014-01-01

DNAJB12 and DNAJB14 are transmembrane proteins in the endoplasmic reticulum (ER) that serve as co-chaperones for Hsc70/Hsp70 heat shock proteins. We demonstrate that over-expression of DNAJB12 or DNAJB14 causes the formation of elaborate membranous structures within cell nuclei, which we designate DJANGOS for DNAJ-associated nuclear globular structures. DJANGOS contain DNAJB12, DNAJB14, Hsc70 and markers of the ER lumen and ER and nuclear membranes. Strikingly, they are evenly distributed underneath the nuclear envelope and are of uniform size in any one nucleus. DJANGOS are composed primarily of single-walled membrane tubes and sheets that connect to the nuclear envelope via a unique configuration of membranes, in which the nuclear pore complex appears anchored exclusively to the outer nuclear membrane, allowing both the inner and outer nuclear membranes to flow past the circumference of the nuclear pore complex into the nucleus. DJANGOS break down rapidly during cell division and reform synchronously in the daughter cell nuclei, demonstrating that they are dynamic structures that undergo coordinate formation and dissolution. Genetic studies showed that the chaperone activity of DNAJ/Hsc70 is required for the formation of DJANGOS. Further analysis of these structures will provide insight into nuclear pore formation and function, activities of molecular chaperones, and mechanisms that maintain membrane identity. PMID:24732912

Tumour necrosis factor-alpha-induced protein 8 (TNFAIP8) expression associated with cell survival and death in cancer cell lines infected with canine distemper virus.

PubMed

Garcia, J A; Ferreira, H L; Vieira, F V; Gameiro, R; Andrade, A L; Eugênio, F R; Flores, E F; Cardoso, T C

2017-06-01

Oncolytic virotherapy is a novel strategy for treatment of cancer in humans and companion animals as well. Canine distemper virus (CDV), a paramyxovirus, has proven to be oncolytic through induction of apoptosis in canine-derived tumour cells, yet the mechanism behind this inhibitory action is poorly understood. In this study, three human mammary tumour cell lines and one canine-derived adenofibrosarcoma cell line were tested regarding to their susceptibility to CDV infection, cell proliferation, apoptosis, mitochondrial membrane potential and expression of tumour necrosis factor-alpha-induced protein 8 (TNFAIP8). CDV replication-induced cytopathic effect, decrease of cell proliferation rates, and >45% of infected cells were considered death and/or under late apoptosis/necrosis. TNFAIP8 and CDVM gene expression were positively correlated in all cell lines. In addition, mitochondrial membrane depolarization was associated with increase in virus titres (p < 0.005). Thus, these results strongly suggest that both human and canine mammary tumour cells are potential candidates for studies concerning CDV-induced cancer therapy. © 2015 John Wiley & Sons Ltd.

Beta2-adrenergic receptor homodimers: Role of transmembrane domain 1 and helix 8 in dimerization and cell surface expression.

PubMed

Parmar, Vikas K; Grinde, Ellinor; Mazurkiewicz, Joseph E; Herrick-Davis, Katharine

2017-09-01

Even though there are hundreds of reports in the published literature supporting the hypothesis that G protein-coupled receptors (GPCR) form and function as dimers this remains a highly controversial area of research and mechanisms governing homodimer formation are poorly understood. Crystal structures revealing homodimers have been reported for many different GPCR. For adrenergic receptors, a potential dimer interface involving transmembrane domain 1 (TMD1) and helix 8 (H8) was identified in crystal structures of the beta 1 -adrenergic (β 1 -AR) and β 2 -AR. The purpose of this study was to investigate a potential role for TMD1 and H8 in dimerization and plasma membrane expression of functional β 2 -AR. Charged residues at the base of TMD1 and in the distal portion of H8 were replaced, singly and in combination, with non-polar residues or residues of opposite charge. Wild type and mutant β 2 -AR, tagged with YFP and expressed in HEK293 cells, were evaluated for plasma membrane expression and function. Homodimer formation was evaluated using bioluminescence resonance energy transfer, bimolecular fluorescence complementation, and fluorescence correlation spectroscopy. Amino acid substitutions at the base of TMD1 and in the distal portion of H8 disrupted homodimer formation and caused receptors to be retained in the endoplasmic reticulum. Mutations in the proximal region of H8 did not disrupt dimerization but did interfere with plasma membrane expression. This study provides biophysical evidence linking a potential TMD1/H8 interface with ER export and the expression of functional β 2 -AR on the plasma membrane. This article is part of a Special Issue entitled: Interactions between membrane receptors in cellular membranes edited by Kalina Hristova. Copyright © 2016 Elsevier B.V. All rights reserved.

Detection and characterisation of multi-drug resistance protein 1 (MRP-1) in human mitochondria.

PubMed

Roundhill, E A; Burchill, S A

2012-03-13

Overexpression of plasma membrane multi-drug resistance protein 1 (MRP-1) can lead to multidrug resistance. In this study, we describe for the first time the expression of mitochondrial MRP-1 in untreated human normal and cancer cells and tissues. MRP-1 expression and subcellular localisation in normal and cancer cells and tissues was examined by differential centrifugation and western blotting, and immunofluorescence microscopy. Viable mitochondria were isolated and MRP-1 efflux activity measured using the calcein-AM functional assay. MRP-1 expression was increased using retroviral infection and specific overexpression confirmed by RNA array. Cell viability was determined by trypan blue exclusion and annexin V-propidium iodide labelling of cells. MRP-1 was detected in the mitochondria of cancer and normal cells and tissues. The efflux activity of mitochondrial MRP-1 was more efficient (55-64%) than that of plasma membrane MRP-1 (11-22%; P<0.001). Induced MRP-1 expression resulted in a preferential increase in mitochondrial MRP-1, suggesting selective targeting to this organelle. Treatment with a non-lethal concentration of doxorubicin (0.85 nM, 8 h) increased mitochondrial and plasma membrane MRP-1, increasing resistance to MRP-1 substrates. For the first time, we have identified MRP-1 with efflux activity in human mitochondria. Mitochondrial MRP-1 may be an exciting new therapeutic target where historically MRP-1 inhibitor strategies have limited clinical success.

Involvement of Rab9 and Rab11 in the intracellular trafficking of TRPC6.

PubMed

Cayouette, Sylvie; Bousquet, Simon M; Francoeur, Nancy; Dupré, Emilie; Monet, Michaël; Gagnon, Hugo; Guedri, Youssef B; Lavoie, Christine; Boulay, Guylain

2010-07-01

TRPC proteins become involved in Ca2+ entry following the activation of Gq-protein coupled receptors. TRPC6 is inserted into the plasma membrane upon stimulation and remains in the plasma membrane as long as the stimulus is present. However, the mechanism that regulates the trafficking of TRPC6 is unclear. In the present study, we highlighted the involvement of two Rab GTPases in the trafficking of TRPC6. Rab9 co-localized in vesicular structures with TRPC6 in HeLa cells and co-immunoprecipitated with TRPC6. When co-expressed with TRPC6, Rab9(S21N), a dominant negative mutant, caused an increase in the level of TRPC6 at the plasma membrane and in TRPC6-mediated Ca2+ entry upon activation by a muscarinic receptor agonist. Similarly, the expression of Rab11 also caused an increase in TRPC6 expression at the cell surface and an increase in TRPC6-mediated Ca2+ entry. The co-expression of TRPC6 with the dominant negative mutant Rab11(S25N) abolished CCh-induced TRPC6 activation and reduced the level of TRPC6 at the plasma membrane. This study demonstrates that the trans-Golgi network and recycling endosomes are involved in the intracellular trafficking of TRPC6 by regulating channel density at the cell surface. 2010 Elsevier B.V. All rights reserved.

CHX14 is a plasma membrane K-efflux transporter that regulates K(+) redistribution in Arabidopsis thaliana.

PubMed

Zhao, Jian; Li, Penghui; Motes, Christy M; Park, Sunghun; Hirschi, Kendal D

2015-11-01

Potassium (K(+) ) is essential for plant growth and development, yet the molecular identity of many K(+) transporters remains elusive. Here we characterized cation/H(+) exchanger (CHX) 14 as a plasma membrane K(+) transporter. CHX14 expression was induced by elevated K(+) and histochemical analysis of CHX14 promoter::GUS transgenic plants indicated that CHX14 was expressed in xylem parenchyma of root and shoot vascular tissues of seedlings. CHX14 knockout (chx14) and CHX14 overexpression seedlings displayed different growth phenotypes during K(+) stress as compared with wild-type seedlings. Roots of mutant seedlings displayed higher K(+) uptake rates than wild-type roots. CHX14 expression in yeast cells deficient in K(+) uptake renders the mutant cells more sensitive to deficiencies of K(+) in the medium. CHX14 mediates K(+) efflux in yeast cells loaded with high K(+) . Uptake experiments using (86) Rb(+) as a tracer for K(+) with both yeast and plant mutants demonstrated that CHX14 expression in yeast and in planta mediated low-affinity K(+) efflux. Functional green fluorescent protein (GFP)-tagged versions of CHX14 were localized to both the yeast and plant plasma membranes. Taken together, we suggest that CHX14 is a plasma membrane K(+) efflux transporter involved in K(+) homeostasis and K(+) recirculation. © 2015 John Wiley & Sons Ltd.

Nitric oxide synthase expression in foetal placentas of cows with retained fetal membranes.

PubMed

Shixin, Fu; Li, Zhang; Chunhai, Luo; Chuang, Xu; Cheng, Xia; Zhe, Wang; Xiaobing, Li

2011-10-01

The objectives of this study were to investigate relationship of retained fetal membranes (RFM) to expression of NOS and NOS mRNA and to analyze pathohistological changes and the distribution of nitric oxide synthase (NOS) in foetal placentas of cows with RFM. Twenty cows were assigned to two groups, a control group (no retained fetal membranes, NRFM, n = 10) and a diseased group (RFM, n = 10). The endpoint method was used to detect the nitric oxide (NO) content and nitric oxide synthase (NOS) activity in foetal placental tissue fluid and the fluorescent quantitation PCR was used to measure the expression of NOS mRNA. Immunohistochemistry and hematoxylin-eosin staining were used to observe pathohistological changes. Tissue from RFM cows showed fibronecrosis of the chorionic villi, and a decreased number of trophoblastic cells. The majority of trophoblastic cells displayed vacuolar degeneration. Interstitium vessels were distended and congested. Expression of induced nitric oxide synthase (iNOS) protein and iNOS mRNA was significantly higher (P < 0.05) in the cytoplasm of placental villus trophoblastic cells in the RFM group. But expression of endothelial nitric oxide synthase (eNOS) protein and eNOS mRNA was significantly lower (P<0.05) in the RFM group. The NO content and NOS activity of cows with RFM were significantly higher (P < 0.05). A high expression of iNOS protein and iNOS mRNA in the cow foetal placenta could produce high content of NO, which might inhibit uterine contraction. So over expression of iNOS protein and iNOS mRNA might be an important agent of retained fetal membranes in cows, and it may be a potential diagnosis biomarker. Copyright © 2010 Elsevier Ltd. All rights reserved.

Biomimetic, ultrathin and elastic hydrogels regulate human neutrophil extravasation across endothelial-pericyte bilayers.

PubMed

Lauridsen, Holly M; Gonzalez, Anjelica L

2017-01-01

The vascular basement membrane-a thin, elastic layer of extracellular matrix separating and encasing vascular cells-provides biological and mechanical cues to endothelial cells, pericytes, and migrating leukocytes. In contrast, experimental scaffolds typically used to replicate basement membranes are stiff and bio-inert. Here, we present thin, porated polyethylene glycol hydrogels to replicate human vascular basement membranes. Like commercial transwells, our hydrogels are approximately 10μm thick, but like basement membranes, the hydrogels presented here are elastic (E: 50-80kPa) and contain a dense network of small pores. Moreover, the inclusion of bioactive domains introduces receptor-mediated biochemical signaling. We compare elastic hydrogels to common culture substrates (E: >2GPa) for human endothelial cell and pericyte monolayers and bilayers to replicate postcapillary venules in vitro. Our data demonstrate that substrate elasticity facilitates differences in vascular phenotype, supporting expression of vascular markers that are increasingly replicative of venules. Endothelial cells differentially express vascular markers, like EphB4, and leukocyte adhesion molecules, such as ICAM-1, with decreased mechanical stiffness. With porated PEG hydrogels we demonstrate the ability to evaluate and observe leukocyte recruitment across endothelial cell and pericyte monolayers and bilayers, reporting that basement membrane scaffolds can significantly alter the rate of vascular migration in experimental systems. Overall, this study demonstrates the creation and utility of a new and accessible method to recapture the mechanical and biological complexity of human basement membranes in vitro.

Molecular Diffusion in Plasma Membranes of Primary Lymphocytes Measured by Fluorescence Correlation Spectroscopy.

PubMed

Staaf, Elina; Bagawath-Singh, Sunitha; Johansson, Sofia

2017-02-01

Fluorescence correlation spectroscopy (FCS) is a powerful technique for studying the diffusion of molecules within biological membranes with high spatial and temporal resolution. FCS can quantify the molecular concentration and diffusion coefficient of fluorescently labeled molecules in the cell membrane. This technique has the ability to explore the molecular diffusion characteristics of molecules in the plasma membrane of immune cells in steady state (i.e., without processes affecting the result during the actual measurement time). FCS is suitable for studying the diffusion of proteins that are expressed at levels typical for most endogenous proteins. Here, a straightforward and robust method to determine the diffusion rate of cell membrane proteins on primary lymphocytes is demonstrated. An effective way to perform measurements on antibody-stained live cells and commonly occurring observations after acquisition are described. The recent advancements in the development of photo-stable fluorescent dyes can be utilized by conjugating the antibodies of interest to appropriate dyes that do not bleach extensively during the measurements. Additionally, this allows for the detection of slowly diffusing entities, which is a common feature of proteins expressed in cell membranes. The analysis procedure to extract molecular concentration and diffusion parameters from the generated autocorrelation curves is highlighted. In summary, a basic protocol for FCS measurements is provided; it can be followed by immunologists with an understanding of confocal microscopy but with no other previous experience of techniques for measuring dynamic parameters, such as molecular diffusion rates.

The Potassium Channel, Kir3.4 Participates in Angiotensin II-Stimulated Aldosterone Production by a Human Adrenocortical Cell Line

PubMed Central

Oki, Kenji; Plonczynski, Maria W.; Lam, Milay Luis; Gomez-Sanchez, Elise P.

2012-01-01

Angiotensin II (A-II) regulation of aldosterone secretion is initiated by inducing cell membrane depolarization, thereby increasing intracellular calcium and activating the calcium calmodulin/calmodulin kinase cascade. Mutations in the selectivity filter of the KCNJ5 gene coding for inward rectifying potassium channel (Kir)3.4 has been found in about one third of aldosterone-producing adenomas. These mutations result in loss of selectivity of the inward rectifying current for potassium, which causes membrane depolarization and opening of calcium channels and activation of the calcium calmodulin/calmodulin kinase cascade and results in an increase in aldosterone secretion. In this study we show that A-II and a calcium ionophore down-regulate the expression of KCNJ5 mRNA and protein. Activation of Kir3.4 by naringin inhibits A-II-stimulated membrane voltage and aldosterone secretion. Overexpression of KCNJ5 in the HAC15 cells using a lentivirus resulted in a decrease in membrane voltage, intracellular calcium, expression of steroidogenic acute regulatory protein, 3-β-hydroxysteroid dehydrogenase 3B2, cytochrome P450 11B1 and cytochrome P450 11B2 mRNA, and aldosterone synthesis. In conclusion, A-II appears to stimulate aldosterone secretion by depolarizing the membrane acting in part through the regulation of the expression and activity of Kir3.4. PMID:22798349

Existence of NEU1 sialidase on mouse thymocytes whose natural substrate is CD5.

PubMed

Kijimoto-Ochiai, Shigeko; Matsumoto-Mizuno, Tokuko; Kamimura, Daisuke; Murakami, Masaaki; Kobayashi, Miwako; Matsuoka, Ichiro; Ochiai, Hiroshi; Ishida, Hideharu; Kiso, Makoto; Kamimura, Keiko; Koda, Toshiaki

2018-05-01

Membrane-bound sialidases in the mouse thymus are unique and mysterious because their activity at pH 6.5 is equal to or higher than that in the acidic region. The pH curve like this has never been reported in membrane-bound form. To clarify this enzyme, we studied the sialidase activities of crude membrane fractions from immature-T, mature-T and non-T cells from C57BL/6 mice and from SM/J mice, a strain with a defect in NEU1 activity. Non-T cells from C57BL/6 mice had high activity at pH 6.5, but those from SM/J mice did not. Neu1 and Neu3 mRNA was shown by real-time PCR to be expressed in T cells and also in non-T cells, whereas Neu2 was expressed mainly in non-T cells and Neu4 was scarcely expressed. However, the in situ hybridization study on the localization of four sialidases in the thymus showed that Neu4 was clearly expressed. We then focused on a sialidase on the thymocyte surface because the possibility of the existence of a sialidase on thymocytes was suggested by peanut agglutinin (PNA) staining after incubation of the cells alone in PBS. This activity was inhibited by NEU1-selective sialidase inhibitor C9-butyl-amide-2-deoxy-2,3-dehydro-N-acetylneuraminic acid. The natural substrate for the cell surface sialidase was identified as clustered differentiation 5 (CD5) by PNA-blot analysis of anti-CD5 immunoprecipitate. We conclude that NEU1 exists on the cell surface of mouse thymocytes and CD5 is a natural substrate for it. Although this is not the main reaction of the membrane-bound thymus-sialidases, it must be important for the thymus.

Analysis of plasma membrane Ca(2+)-ATPase expression in control and SV40-transformed human fibroblasts.

PubMed

Reisner, P D; Brandt, P C; Vanaman, T C

1997-01-01

It has been long known that neoplastic transformation is accompanied by a lowered requirement for extracellular Ca2+ for growth. The studies presented here demonstrate that human fibroblastic cell lines produce the two commonly found 'housekeeping' isoforms of the plasma membrane Ca(2+)-ATPase (PMCA), PMCA1b and 4b, and at the expression of both is demonstrably lower in cell lines neoplastically transformed by SV40 than in the corresponding parental cell lines. Western blot analyses of lysates from control (GM00037) and SV40-transformed (GM00637) skin fibroblasts revealed a 138 kDa PMCA whose level was significantly lower in the SV40-transformed cells relative to either total cellular protein or alpha-tubulin. Similar analyses of plasma membrane preparations from control WI-38) and SV40-transformed (WI-38VA13) lung fibroblasts revealed 3-4-fold lower levels of PMCA in the SV40-transformed cells. Competitive ELISAs performed on detergent solubilized plasma membrane preparations indicated at least 3-4-fold lower levels of PMCA in the SV40-transformed cell lines compared to controls. Reverse transcriptase coupled-PCR analyses showed that PMCA1b and PMCA4b were the only isoforms expressed in all four cell lines. The PMCA4b mRNA level detected by Northern analysis also was substantially lower in SV40 transformed skin fibroblasts than in non-transformed fibroblasts. Quantitative RT-PCR analyses showed levels of PMCA1b and 4b mRNAs to be 5 and 10-fold lower, respectively, in GM00637 than in GM00037 when the levels of PCR products were normalized to glyceraldehyde-3-phosphate dehydrogenase (G3PDH) mRNA. These results demonstrate that the expression of these distinct PMCA genes is substantially lower in SV40 transformed human skin and lung fibroblasts and may be coordinately regulated in these cells.

Expression of Cat Podoplanin in Feline Squamous Cell Carcinomas.

PubMed

Itai, Shunsuke; Yamada, Shinji; Kaneko, Mika K; Harada, Hiroyuki; Kagawa, Yumiko; Konnai, Satoru; Kato, Yukinari

2017-12-01

Oral squamous cell carcinoma is an aggressive tumor in cats; however, molecular-targeted therapies against this tumor, including antibody therapy, have not been developed. Sensitive and specific monoclonal antibodies (mAbs) against highly expressed membrane proteins are needed to develop antibody therapies. Podoplanin, a type I transmembrane glycoprotein, is expressed in many human malignant tumors, including brain tumor, esophageal cancer, lung cancer, mesothelioma, and oral cancer. Podoplanin binds to C-type lectin-like receptor-2 (CLEC-2) and activates platelet aggregation, which is involved in cancer metastasis. Until now, we have established several mAbs against podoplanin in humans, mice, rats, rabbits, dogs, cattle, and cats. We have reported podoplanin expression in canine melanoma and squamous cell carcinomas using an anti-dog podoplanin mAb PMab-38. In this study, we investigated podoplanin expression in 40 feline squamous cell carcinomas (14 cases of mouth floor, 13 of skin, 9 of ear, and 4 of tongue) by immunohistochemical analysis using an anti-cat podoplanin mAb PMab-52, which we recently developed by cell-based immunization and screening (CBIS) method. Of the total 40 cases, 38 (95%) showed positive staining for PMab-52. In particular, 12 cases (30%) showed a strong membrane-staining pattern of squamous cell carcinoma cells. PMab-52 can be useful for antibody therapy against feline podoplanin-expressing squamous cell carcinomas.

Inhibition of PIM1 kinase attenuates inflammation-induced pro-labour mediators in human foetal membranes in vitro.

PubMed

Lim, Ratana; Barker, Gillian; Lappas, Martha

2017-06-01

Does proviral integration site for Moloney murine leukaemic virus (PIM)1 kinase play a role in regulating the inflammatory processes of human labour and delivery? PIM1 kinase plays a critical role in foetal membranes in regulating pro-inflammatory and pro-labour mediators. Infection and inflammation have strong causal links to preterm delivery by stimulating pro-inflammatory cytokines and collagen degrading enzymes, which can lead to rupture of membranes. PIM1 has been shown to have a role in immune regulation and inflammation in non-gestational tissues; however, its role has not been explored in the field of human labour. PIM1 expression was analysed in myometrium and/or foetal membranes obtained at term and preterm (n = 8-9 patients per group). Foetal membranes, freshly isolated amnion cells and primary myometrial cells were used to investigate the effect of PIM1 inhibition on pro-labour mediators (n = 5 patients per treatment group). Foetal membranes, from term and preterm, were obtained from non-labouring and labouring women, and from preterm pre-labour rupture of membranes (PPROM) (n = 9 per group). Amnion was collected from women with and without preterm chorioamnionitis (n = 8 per group). Expression of PIM1 kinase was determined by qRT-PCR and western blotting. To determine the effect of PIM1 kinase inhibition on the expression of pro-inflammatory and pro-labour mediators induced by bacterial products lipopolysaccharide (LPS) (10 μg/ml) and flagellin (1 μg/ml) and pro-inflammatory cytokine tumour necrosis factor (TNF) (10 ng/ml), chemical inhibitors SMI-4a (20 μM) and AZD1208 (50 μM) were used in foetal membrane explants and siRNA against PIM1 was used in primary amnion cells. Statistical significance was set at P < 0.05. PIM1 expression was significantly increased in foetal membranes after spontaneous term labour compared to no labour at term and in amnion with preterm chorioamnionitis compared to preterm with no chorioamnionitis. There was no change in PIM1 expression with preterm labour or PPROM compared to preterm with no labour or PPROM. In human foetal membranes, PIM1 inhibitors SMI-4a and AZD1208 significantly decreased the expression of pro-inflammatory cytokine interleukin-6 (IL6) and chemokines CXCL8 and CCL2 mRNA and release, prostaglandin prostaglandin F2α (PGF2α) release, adhesion molecule intercellular adhesion molecule 1 mRNA expression and release, and oxidative stress marker 8-isoprostane release after stimulation with either LPS or flagellin. Primary amnion cells transfected with PIM1 siRNA also showed decreased expression of IL6, CXCL8 and CCL2, PTGS2 mRNA and PGF2α release, and matrix metalloproteinase-9 (MMP9) expression, when stimulated with TNF. None. The conclusions were drawn from in vitro experiments using foetal membrane explants and primary cells isolated from amnion. Animal models are necessary to determine whether PIM1 kinase inhibitors can prevent spontaneous preterm birth in vivo. PIM1 kinase inhibitors may provide a novel therapeutic approach for preventing spontaneous preterm birth. Associate Professor Martha Lappas is supported by a Career Development Fellowship from the National Health and Medical Research Council (NHMRC; grant no. 1047025). Funding for this study was provided by the NHMRC (grant no. 1058786), Norman Beischer Medical Research Foundation and the Mercy Research Foundation. The authors have no conflict of interest. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A cell culture technique for human epiretinal membranes to describe cell behavior and membrane contraction in vitro.

PubMed

Wertheimer, Christian; Eibl-Lindner, Kirsten H; Compera, Denise; Kueres, Alexander; Wolf, Armin; Docheva, Denitsa; Priglinger, Siegfried G; Priglinger, Claudia; Schumann, Ricarda G

2017-11-01

To introduce a human cell culture technique for investigating in-vitro behavior of primary epiretinal cells and membrane contraction of fibrocellular tissue surgically removed from eyes with idiopathic macular pucker. Human epiretinal membranes were harvested from ten eyes with idiopathic macular pucker during standard vitrectomy. Specimens were fixed on cell culture plastic using small entomological pins to apply horizontal stress to the tissue, and then transferred to standard cell culture conditions. Cell behavior of 400 epiretinal cells from 10 epiretinal membranes was observed in time-lapse microscopy and analyzed in terms of cell migration, cell velocity, and membrane contraction. Immunocytochemistry was performed for cell type-specific antigens. Cell specific differences in migration behavior were observed comprising two phenotypes: (PT1) epiretinal cells moving fast, less directly, with small round phenotype and (PT2) epiretinal cells moving slowly, directly, with elongated large phenotype. No mitosis, no outgrowth and no migration onto the plastic were seen. Horizontal contraction measurements showed variation between specimens. Masses of epiretinal cells with a myofibroblast-like phenotype expressed cytoplasmatic α-SMA stress fibers and correlated with cell behavior characteristics (PT2). Fast moving epiretinal cells (PT1) were identified as microglia by immunostaining. This in-vitro technique using traction application allows for culturing surgically removed epiretinal membranes from eyes with idiopathic macular pucker, demonstrating cell behavior and membrane contraction of primary human epiretinal cells. Our findings emphasize the abundance of myofibroblasts, the presence of microglia and specific differences of cell behavior in these membranes. This technique has the potential to improve the understanding of pathologies at the vitreomacular interface and might be helpful in establishing anti-fibrotic treatment strategies.

Endocytosis and membrane receptor internalization: implication of F-BAR protein Carom

PubMed Central

Xu, Yanjie; Liu, Suxuan; Xia, Jixiang; Stein, Sam; Ramon, Cueto; Xi, Hang; Wang, Luqiao; Xiong, Xinyu; Zhang, Lixiao; He, Dingwen; Yang, William; Zhao, Xianxian; Cheng, Xiaoshu; Yang, Xiaofeng; Wang, Hong

2016-01-01

Endocytosis is a cellular process mostly responsible for membrane receptor internalization. Cell membrane receptors bind to their ligands and form a complex which can be internalized. We previously proposed that F-BAR protein initiates membrane curvature and mediates endocytosis via their binding partners. However, F-BAR protein partners involved in membrane receptor endocytosis and the regulatory mechanism remain unknown. In this study, we established a group of database mining strategies to explore mechanisms underlying receptor-related endocytosis. We identified 34 endocytic membrane receptors and 10 regulating proteins for vesicle formation in clathrin-dependent endocytosis (CDE), a major process of membrane receptor internalization. We found that F-BAR protein FCHSD2 (Carom) may facilitate endocytosis via 9 endocytic partners. Carom is highly expressed, along with highly expressed endocytic membrane receptors and partners, in endothelial cells and macrophages. We established 3 models of Carom-receptor complex and their intracellular trafficking based on protein-protein interaction and subcellular localization. We conclude that Carom may mediate receptor endocytosis and transport endocytic receptors to the cytoplasm for receptor signaling and lysosome/proteasome degradation, or to the nucleus for RNA processing, gene transcription and DNA repair. PMID:28199211

Integrated light and scanning electron microscopy of GFP-expressing cells.

PubMed

Peddie, Christopher J; Liv, Nalan; Hoogenboom, Jacob P; Collinson, Lucy M

2014-01-01

Integration of light and electron microscopes provides imaging tools in which fluorescent proteins can be localized to cellular structures with a high level of precision. However, until recently, there were few methods that could deliver specimens with sufficient fluorescent signal and electron contrast for dual imaging without intermediate staining steps. Here, we report protocols that preserve green fluorescent protein (GFP) in whole cells and in ultrathin sections of resin-embedded cells, with membrane contrast for integrated imaging. Critically, GFP is maintained in a stable and active state within the vacuum of an integrated light and scanning electron microscope. For light microscopists, additional structural information gives context to fluorescent protein expression in whole cells, illustrated here by analysis of filopodia and focal adhesions in Madin Darby canine kidney cells expressing GFP-Paxillin. For electron microscopists, GFP highlights the proteins of interest within the architectural space of the cell, illustrated here by localization of the conical lipid diacylglycerol to cellular membranes. © 2014 Elsevier Inc. All rights reserved.

A preliminary study of aquaporin 1 immunolocalization in chronic subdural hematoma membranes.

PubMed

Basaldella, Luca; Perin, Alessandro; Orvieto, Enrico; Marton, Elisabetta; Itskevich, David; Dei Tos, Angelo Paolo; Longatti, Pierluigi

2010-07-01

Aquaporin 1 (AQP1) is a molecular water channel expressed in many anatomical locations, particularly in epithelial barriers specialized in water transport. The aim of this study was to investigate AQP1 expression in chronic subdural hematoma (CSDH) membranes. In this preliminary study, 11 patients with CSDH underwent burr hole craniectomy and drainage. Membrane specimens were stained with a monoclonal antibody targeting AQP1 for immunohistochemical analysis. The endothelial cells of the sinusoid capillaries of the outer membranes exhibited an elevated immunoreactivity to AQP1 antibody compared to the staining intensity of specimens from the inner membrane and normal dura. These findings suggest that the outer membrane might be the source of the increased fluid accumulation responsible for chronic hematoma enlargement.

Characterisation of FAP-1 expression and CD95 mediated apoptosis in the A818-6 pancreatic adenocarcinoma differentiation system.

PubMed

Winterhoff, Boris J N; Arlt, Alexander; Duttmann, Angelika; Ungefroren, Hendrik; Schäfer, Heiner; Kalthoff, Holger; Kruse, Marie-Luise

2012-03-01

The present study investigated the expression and localisation of FAP-1 (Fas associated phosphatase-1) and CD95 in a 3D differentiation model in comparison to 2D monolayers of the pancreatic adenocarcinoma cell line A818-6. Under non-adherent growth conditions, A818-6 cells differentiate into 3D highly organised polarised epithelial hollow spheres, resembling duct-like structures. A818-6 cells showed a differentiation-dependent FAP-1 localisation. Cells grown as 2D monolayers revealed FAP-1 staining in a juxtanuclear cisternal position, as well as localisation in the nucleus. After differentiation into hollow spheres, FAP-1 was relocated towards the actin cytoskeleton beneath the outer plasma membrane of polarised cells and no further nuclear localisation was observed. CD95 surface staining was found only in a subset of A818-6 monolayer cells, while differentiated hollow spheres appeared to express CD95 in all cells of a given sphere. We rarely observed co-localisation of CD95 and FAP-1 in A818-6 monolayer cells, but strong co-localisation beneath the outer plasma membrane in polarised cells. Analysis of surface expression by flow cytometry revealed that only a subset (36%) of monolayer cells showed CD95 surface expression, and after induction of hollow spheres, CD95 presentation at the outer plasma membrane was reduced to 13% of hollow spheres. Induction of apoptosis by stimulation with agonistic anti-CD95 antibodies, resulted in increased caspase activity in both, monolayer cells and hollow spheres. Knock down of FAP-1 mRNA in A818-6 monolayer cells did not alter resposiveness to CD95 agonistic antibodies. These data suggested that CD95 signal transduction was not affected by FAP-1 expression in A818-6 monolayer cells. In differentiated 3D hollow spheres, we found a polarisation-induced co-localisation of CD95 and FAP-1. A tight control of receptor surface representation and signalling induced apoptosis ensures controlled removal of individual cells instead of a "snowball effect" of apoptotic events. Copyright © 2011 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

Plasmin on adherent cells: from microvesiculation to apoptosis

PubMed Central

Doeuvre, Loïc; Plawinski, Laurent; Goux, Didier; Vivien, Denis; Anglés-Cano, Eduardo

2010-01-01

SYNOPSIS Cell activation by stressors is characterised by a sequence of detectable phenotypic cell changes. The strength of a given stimulus induces modifications in the activity of membrane phospholipids transporters and calpains, which leads to phosphatidylserine exposure, membrane blebbing and the release of microparticles (nanoscale membrane vesicles). This vesiculation could be considered as a warning signal that may be followed, if the stimulus is maintained, by cell detachment-induced apoptosis. In this study, plasminogen incubated onto adherent cells is activated into plasmin by constitutively expressed tPA or uPA. Plasmin formed on the cellular membrane then induces an unique response characterized by membrane blebbing and vesiculation. Hitherto unknown for plasmin, these membrane changes are similar to those induced by thrombin on platelets. If plasmin formation evolves, matrix proteins are then degraded, cells lose attachment and enter the apoptotic process, characterized by DNA fragmentation and electron microscopy features. This sequence of events was experimentally documented at all these stages. Since other proteolytic or inflammatory stimuli may evoke similar responses by distinct adherent cells, this sequence can be applied to distinguish activated adherent cells from cells entering the apoptotic process. This is a major definition crucial to the identification of mediators, inhibitors and potential therapeutic agents. PMID:20846121

[Eukaryotic Expression and Immunogenic Research of Recombination Ebola Virus Membrane Protein Gp-Fc].

PubMed

Zhang, Xiaoguang; Yang, Ren; Wang, Jiao; Wang, Xuan; Hou, Mieling; An, Lina; Zhu, Ying; Cao, Yuxi; Zeng, Yi

2016-01-01

We used 293 cells to express the recombinant membrane protein of the Ebola virus. Then, the immunogenicity of the recombinant protein was studied by immunized BALB/c mice. According to the codon use frequency of humans, the gene encoding the extracellular domain of the Ebola virus membrane protein was optimized, synthesized, and inserted into the eukaryotic expression plasmid pXG-Fc to construct the human IgG Fc and Ebola GP fusion protein expression plasmid pXG-modGP-Fc. To achieve expression, the fusion protein expression vector was transfected into high-density 293 cells using transient transfection technology. The recombinant protein was purified by protein A affinity chromatography. BALB/c mice were immunized with the purified fusion protein, and serum antibody titers evaluated by an indirect enzyme-linked immunosorbent assay (ELISA). Purification and analyses of the protein revealed that the eukaryotic expression vector could express the recombinant protein GP-Fc effectively, and that the recombinant protein in the supernatant of the cell culture was present as a dimer. After immunization with the purified recombinant protein, a high titer of antigen-specific IgG could be detected in the serum of immunized mice by indirect ELISA, showing that the recombinant protein had good immunogenicity. These data suggest that we obtained a recombinant protein with good immunogenicity. Our study is the basis for development of a vaccine against the Ebola virus and for screening of monoclonal antibodies.

Evidence that the Essential Response Regulator YycF in Streptococcus pneumoniae Modulates Expression of Fatty Acid Biosynthesis Genes and Alters Membrane Composition†

PubMed Central

Mohedano, M. Luz; Overweg, Karin; de la Fuente, Alicia; Reuter, Mark; Altabe, Silvia; Mulholland, Francis; de Mendoza, Diego; López, Paloma; Wells, Jerry M.

2005-01-01

The YycFG two-component system, originally identified in Bacillus subtilis, is highly conserved among gram-positive bacteria with low G+C contents. In Streptococcus pneumoniae, the YycF response regulator has been reported to be essential for cell growth, but the signal to which it responds and the gene members of the regulon remain unclear. In order to investigate the role of YycFG in S. pneumoniae, we increased the expression of yycF by using a maltose-inducible vector and analyzed the genome-wide effects on transcription and protein expression during the course of yycF expression. The induction of yycF expression increased histidine kinase yycG transcript levels, suggesting an autoregulation of the yycFG operon. Evidence from both proteomic and microarray transcriptome studies as well as analyses of membrane fatty acid composition indicated that YycFG is involved in the regulation of fatty acid biosynthesis pathways and in determining fatty acid chain lengths in membrane lipids. In agreement with recent transcriptome data on pneumococcal cells depleted of YycFG, we also identified several other potential members of the YycFG regulon that are required for virulence and cell wall biosynthesis and metabolism. PMID:15774879

Autodisplay for the co-expression of lipase and foldase on the surface of E. coli: washing with designer bugs

PubMed Central

2014-01-01

Background Lipases including the lipase from Burkholderia cepacia are in a main focus in biotechnology research since many years because of their manifold possibilities for application in industrial processes. The application of Burkholderia cepacia lipase for these processes appears complicated because of the need for support by a chaperone, the lipase specific foldase. Purification and reconstitution protocols therefore interfere with an economic implementation of such enzymes in industry. Autodisplay is a convenient method to express a variety of passenger proteins on the surface of E. coli. This method makes subsequent purification steps to obtain the protein of interest unnecessary. If enzymes are used as passengers, the corresponding cells can simply be applied as whole cell biocatalysts. Furthermore, enzymes surface displayed in this manner often acquire stabilization by anchoring within the outer membrane of E. coli. Results The lipase and its chaperone foldase from B. cepacia were co-expressed on the surface of E. coli via autodisplay. The whole cell biocatalyst obtained thereby exhibited an enzymatic activity of 2.73 mU mL-1 towards the substrate p-nitrophenyl palmitate when applied in an OD578 =1. Outer membrane fractions prepared from the same culture volume showed a lipase activity of 4.01 mU mL-1. The lipase-whole cell biocatalyst as well as outer membrane preparations thereof were used in a standardized laundry test, usually adopted to determine the power of washing agents. In this test, the lipase whole cell biocatalyst and the membrane preparation derived thereof exhibited the same lipolytic activity as the purified lipase from B. cepacia and a lipase preparation which is already applied in commercial washing agents. Conclusions Co-expression of both the lipase and its chaperone foldase on the surface of E. coli yields a lipid degrading whole cell biocatalyst. Therefore the chaperone supported folding process, absolutely required for the lipolytic activity appears not to be hindered by surface display. Furthermore, the cells and the membrane preparations appeared to be stable enough to endure a European standard laundry test and show efficient fat removal properties herein. PMID:24476025

Changes in plasma membrane lipids, aquaporins and proton pump of broccoli roots, as an adaptation mechanism to salinity.

PubMed

López-Pérez, Luis; Martínez-Ballesta, María Del Carmen; Maurel, Christophe; Carvajal, Micaela

2009-03-01

Salinity stress is known to modify the plasma membrane lipid and protein composition of plant cells. In this work, we determined the effects of salt stress on the lipid composition of broccoli root plasma membrane vesicles and investigated how these changes could affect water transport via aquaporins. Brassica oleracea L. var. Italica plants treated with different levels of NaCl (0, 40 or 80mM) showed significant differences in sterol and fatty acid levels. Salinity increased linoleic (18:2) and linolenic (18:3) acids and stigmasterol, but decreased palmitoleic (16:1) and oleic (18:1) acids and sitosterol. Also, the unsaturation index increased with salinity. Salinity increased the expression of aquaporins of the PIP1 and PIP2 subfamilies and the activity of the plasma membrane H(+)-ATPase. However, there was no effect of NaCl on water permeability (P(f)) values of root plasma membrane vesicles, as determined by stopped-flow light scattering. The counteracting changes in lipid composition and aquaporin expression observed in NaCl-treated plants could allow to maintain the membrane permeability to water and a higher H(+)-ATPase activity, thereby helping to reduce partially the Na(+) concentration in the cytoplasm of the cell while maintaining water uptake via cell-to-cell pathways. We propose that the modification of lipid composition could affect membrane stability and the abundance or activity of plasma membrane proteins such as aquaporins or H(+)-ATPase. This would provide a mechanism for controlling water permeability and for acclimation to salinity stress.

Immunological recognition of different forms of the neurotensin receptor in transfected cells and rat brain.

PubMed Central

Boudin, H; Grauz-Guyon, A; Faure, M P; Forgez, P; Lhiaubet, A M; Dennis, M; Beaudet, A; Rostene, W; Pelaprat, D

1995-01-01

In this work, the molecular forms of the rat neurotensin receptor (NTR) expressed in transfected Chinese hamster ovary (CHO) cells, in infected Sf9 insect cells and in rat cerebral cortex were immunologically detected by means of an anti-peptide antibody raised against a fragment of the third intracellular loop of the receptor. Immunoblot experiments against a fusion protein indicated that the anti-peptide antibody recognized, under denaturing conditions, the corresponding amino acid sequence within the NTR. In immunoblot analysis of membranes from NTR-transfected CHO cells, high levels of immunoreactivity were observed between 60 and 72 kDa, while only a faint labelling was observed at 47 kDa, the molecular mass deduced for the rat NTR cDNA. The bands of high molecular mass were no longer observed after deglycosylation of membrane proteins by peptide N-glycosidase F, indicating that they represented glycosylated forms of the receptor. Extracts of membranes derived from baculovirus-infected Sf9 insect-cells expressing the NTR provided a quite different immunoblot pattern, since the major band detected in that case was at 47 kDa, the molecular size of the non-glycosylated receptor. Taken together, these data show that, while most of the NTR protein was glycosylated in CHO cells, it was unglycosylated in Sf9 insect-cells. In addition, molecular sizes of the receptor proteins observed in these two cell lines differed from those obtained for the NTR endogenously expressed in the rat cerebral cortex of 7 day-old rats, where bands at 56 and 54 kDa were detected. Binding experiments carried out on membrane preparations obtained from baculovirus-infected Sf9 cells demonstrated that the immunogenic sequence was still accessible to the antibody when the receptor was embedded in the cell membrane. Immunohistochemical studies carried out on both transfected CHO cells and infected Sf9 cells confirmed this interpretation and further indicated that the antibody could be applied in the visualization of the receptor. Images Figure 1 Figure 2 Figure 3 Figure 5 PMID:7826341

Cell Surface Expression of Human Ether-a-go-go-related Gene (hERG) Channels Is Regulated by Caveolin-3 Protein via the Ubiquitin Ligase Nedd4-2*

PubMed Central

Guo, Jun; Wang, Tingzhong; Li, Xian; Shallow, Heidi; Yang, Tonghua; Li, Wentao; Xu, Jianmin; Fridman, Michael D.; Yang, Xiaolong; Zhang, Shetuan

2012-01-01

The human ether-a-go-go-related gene (hERG) encodes the rapidly activating delayed rectifier potassium channel (IKr) which plays an important role in cardiac repolarization. A reduction or increase in hERG current can cause long or short QT syndrome, respectively, leading to fatal cardiac arrhythmias. The channel density in the plasma membrane is a key determinant of the whole cell current amplitude. To gain insight into the molecular mechanisms for the regulation of hERG density at the plasma membrane, we used whole cell voltage clamp, Western blotting, and immunocytochemical methods to investigate the effects of an integral membrane protein, caveolin-3 (Cav3) on hERG expression levels. Our data demonstrate that Cav3, hERG, and ubiquitin-ligase Nedd4-2 interact with each other and form a complex. Expression of Cav3 thus enhances the hERG-Nedd4-2 interaction, leading to an increased ubiquitination and degradation of mature, plasma-membrane localized hERG channels. Disrupting Nedd4-2 interaction with hERG by mutations eliminates the effects of Cav3 on hERG channels. Knockdown of endogenous Cav3 or Nedd4-2 in cultured neonatal rat ventricular myocytes using siRNA led to an increase in native IKr. Our data demonstrate that hERG expression in the plasma membrane is regulated by Cav3 via Nedd4-2. These findings extend our understanding of the regulation of hERG channels and cardiac electrophysiology. PMID:22879586

Constitutive Expression of the Maltoporin LamB in the Absence of OmpR Damages the Cell Envelope▿ †

PubMed Central

Reimann, Sylvia A.; Wolfe, Alan J.

2011-01-01

Cells experience multiple environmental stimuli simultaneously. To survive, they must respond accordingly. Unfortunately, the proper response to one stress easily could make the cell more susceptible to a second coexistent stress. To deal with such a problem, a cell must possess a mechanism that balances the need to respond simultaneously to both stresses. Our recent studies of ompR malT(Con) double mutants show that elevated expression of LamB, the outer membrane porin responsible for maltose uptake, causes cell death when the osmoregulator OmpR is disabled. To obtain insight into the nature of the death experienced by ompR malT(Con) mutants, we described the death process. On the basis of microscopic and biochemical approaches, we conclude that death results from a loss of membrane integrity. On the basis of an unbiased genome-wide search for suppressor mutations, we conclude that this loss of membrane integrity results from a LamB-induced envelope stress that the cells do not sufficiently perceive and thus do not adequately accommodate. Finally, we conclude that this envelope stress involves an imbalance in the lipopolysaccharide/porin composition of the outer membrane and an increased requirement for inorganic phosphate. PMID:21131484

The plasma membrane Ca2+ pump PMCA4b inhibits the migratory and metastatic activity of BRAF mutant melanoma cells.

PubMed

Hegedũs, Luca; Garay, Tamás; Molnár, Eszter; Varga, Karolina; Bilecz, Ágnes; Török, Szilvia; Padányi, Rita; Pászty, Katalin; Wolf, Matthias; Grusch, Michael; Kállay, Enikõ; Döme, Balázs; Berger, Walter; Hegedũs, Balázs; Enyedi, Agnes

2017-06-15

Oncogenic mutations of BRAF lead to constitutive ERK activity that supports melanoma cell growth and survival. While Ca 2+ signaling is a well-known regulator of tumor progression, the crosstalk between Ca 2+ signaling and the Ras-BRAF-MEK-ERK pathway is much less explored. Here we show that in BRAF mutant melanoma cells the abundance of the plasma membrane Ca 2+ ATPase isoform 4b (PMCA4b, ATP2B4) is low at baseline but markedly elevated by treatment with the mutant BRAF specific inhibitor vemurafenib. In line with these findings gene expression microarray data also shows decreased PMCA4b expression in cutaneous melanoma when compared to benign nevi. The MEK inhibitor selumetinib-similarly to that of the BRAF-specific inhibitor-also increases PMCA4b levels in both BRAF and NRAS mutant melanoma cells suggesting that the MAPK pathway is involved in the regulation of PMCA4b expression. The increased abundance of PMCA4b in the plasma membrane enhances [Ca 2+ ] i clearance from cells after Ca 2+ entry. Moreover we show that both vemurafenib treatment and PMCA4b overexpression induce marked inhibition of migration of BRAF mutant melanoma cells. Importantly, reduced migration of PMCA4b expressing BRAF mutant cells is associated with a marked decrease in their metastatic potential in vivo. Taken together, our data reveal an important crosstalk between Ca 2+ signaling and the MAPK pathway through the regulation of PMCA4b expression and suggest that PMCA4b is a previously unrecognized metastasis suppressor. © 2016 UICC.

Type II integral membrane protein, TM of J paramyxovirus promotes cell-to-cell fusion.

PubMed

Li, Zhuo; Hung, Cher; Paterson, Reay G; Michel, Frank; Fuentes, Sandra; Place, Ryan; Lin, Yuan; Hogan, Robert J; Lamb, Robert A; He, Biao

2015-10-06

Paramyxoviruses include many important animal and human pathogens. Most paramyxoviruses have two integral membrane proteins: fusion protein (F) and attachment proteins hemagglutinin, hemagglutinin-neuraminidase, or glycoprotein (G), which are critical for viral entry into cells. J paramyxovirus (JPV) encodes four integral membrane proteins: F, G, SH, and transmembrane (TM). The function of TM is not known. In this work, we have generated a viable JPV lacking TM (JPV∆TM). JPV∆TM formed opaque plaques compared with JPV. Quantitative syncytia assays showed that JPV∆TM was defective in promoting cell-to-cell fusion (i.e., syncytia formation) compared with JPV. Furthermore, cells separately expressing F, G, TM, or F plus G did not form syncytia whereas cells expressing F plus TM formed some syncytia. However, syncytia formation was much greater with coexpression of F, G, and TM. Biochemical analysis indicates that F, G, and TM interact with each other. A small hydrophobic region in the TM ectodomain from amino acid residues 118 to 132, the hydrophobic loop (HL), was important for syncytial promotion, suggesting that the TM HL region plays a critical role in cell-to-cell fusion.

Serine 129 phosphorylation of membrane-associated α-synuclein modulates dopamine transporter function in a G protein–coupled receptor kinase–dependent manner

PubMed Central

Hara, Susumu; Arawaka, Shigeki; Sato, Hiroyasu; Machiya, Youhei; Cui, Can; Sasaki, Asuka; Koyama, Shingo; Kato, Takeo

2013-01-01

Most α-synuclein (α-syn) deposited in Lewy bodies, the pathological hallmark of Parkinson disease (PD), is phosphorylated at Ser-129. However, the physiological and pathological roles of this modification are unclear. Here we investigate the effects of Ser-129 phosphorylation on dopamine (DA) uptake in dopaminergic SH-SY5Y cells expressing α-syn. Subcellular fractionation of small interfering RNA (siRNA)–treated cells shows that G protein–coupled receptor kinase 3 (GRK3), GRK5, GRK6, and casein kinase 2 (CK2) contribute to Ser-129 phosphorylation of membrane-associated α-syn, whereas cytosolic α-syn is phosphorylated exclusively by CK2. Expression of wild-type α-syn increases DA uptake, and this effect is diminished by introducing the S129A mutation into α-syn. However, wild-type and S129A α-syn equally increase the cell surface expression of dopamine transporter (DAT) in SH-SY5Y cells and nonneuronal HEK293 cells. In addition, siRNA-mediated knockdown of GRK5 or GRK6 significantly attenuates DA uptake without altering DAT cell surface expression, whereas knockdown of CK2 has no effect on uptake. Taken together, our results demonstrate that membrane-associated α-syn enhances DA uptake capacity of DAT by GRKs-mediated Ser-129 phosphorylation, suggesting that α-syn modulates intracellular DA levels with no functional redundancy in Ser-129 phosphorylation between GRKs and CK2. PMID:23576548

Segregation of two spectrin isoforms: polarized membrane-binding sites direct polarized membrane skeleton assembly.

PubMed

Dubreuil, R R; Maddux, P B; Grushko, T A; MacVicar, G R

1997-10-01

Spectrin isoforms are often segregated within specialized plasma membrane subdomains where they are thought to contribute to the development of cell surface polarity. It was previously shown that ankyrin and beta spectrin are recruited to sites of cell-cell contact in Drosophila S2 cells expressing the homophilic adhesion molecule neuroglian. Here, we show that neuroglian has no apparent effect on a second spectrin isoform (alpha beta H), which is constitutively associated with the plasma membrane in S2 cells. Another membrane marker, the Na,K-ATPase, codistributes with ankyrin and alpha beta spectrin at sites of neuroglian-mediated contact. The distributions of these markers in epithelial cells in vivo are consistent with the order of events observed in S2 cells. Neuroglian, ankyrin, alpha beta spectrin, and the Na,K-ATPase colocalize at the lateral domain of salivary gland cells. In contrast, alpha beta H spectrin is sorted to the apical domain of salivary gland and somatic follicle cells. Thus, the two spectrin isoforms respond independently to positional cues at the cell surface: in one case an apically sorted receptor and in the other case a locally activated cell-cell adhesion molecule. The results support a model in which the membrane skeleton behaves as a transducer of positional information within cells.

Antagonizing effects of membrane-acting androgens on the eicosanoid receptor OXER1 in prostate cancer

PubMed Central

Kalyvianaki, Konstantina; Gebhart, Veronika; Peroulis, Nikolaos; Panagiotopoulou, Christina; Kiagiadaki, Fotini; Pediaditakis, Iosif; Aivaliotis, Michalis; Moustou, Eleni; Tzardi, Maria; Notas, George; Castanas, Elias; Kampa, Marilena

2017-01-01

Accumulating evidence during the last decades revealed that androgen can exert membrane initiated actions that involve signaling via specific kinases and the modulation of significant cellular processes, important for prostate cancer cell growth and metastasis. Results of the present work clearly show that androgens can specifically act at the membrane level via the GPCR oxoeicosanoid receptor 1 (OXER1) in prostate cancer cells. In fact, OXER1 expression parallels that of membrane androgen binding in prostate cancer cell lines and tumor specimens, while in silico docking simulation of OXER1 showed that testosterone could bind to OXER1 within the same grove as 5-OxoETE, the natural ligand of OXER1. Interestingly, testosterone antagonizes the effects of 5-oxoETE on specific signaling pathways and rapid effects such as actin cytoskeleton reorganization that ultimately can modulate cell migration and metastasis. These findings verify that membrane-acting androgens exert specific effects through an antagonistic interaction with OXER1. Additionally, this interaction between androgen and OXER1, which is an arachidonic acid metabolite receptor expressed in prostate cancer, provides a novel link between steroid and lipid actions and renders OXER1 as new player in the disease. These findings should be taken into account in the design of novel therapeutic approaches in prostate cancer. PMID:28290516

Visualisation of an nsPEF induced calcium wave using the genetically encoded calcium indicator GCaMP in U87 human glioblastoma cells.

PubMed

Carr, Lynn; Bardet, Sylvia M; Arnaud-Cormos, Delia; Leveque, Philippe; O'Connor, Rodney P

2018-02-01

Cytosolic, synthetic chemical calcium indicators are typically used to visualise the rapid increase in intracellular calcium ion concentration that follows nanosecond pulsed electric field (nsPEF) application. This study looks at the application of genetically encoded calcium indicators (GECIs) to investigate the spatiotemporal nature of nsPEF-induced calcium signals using fluorescent live cell imaging. Calcium responses to 44kV/cm, 10ns pulses were observed in U87-MG cells expressing either a plasma membrane targeted GECI (GCaMP5-G), or one cytosolically expressed (GCaMP6-S), and compared to the response of cells loaded with cytosolic or plasma membrane targeted chemical calcium indicators. Application of 100 pulses, to cells containing plasma membrane targeted indicators, revealed a wave of calcium across the cell initiating at the cathode side. A similar spatial wave was not observed with cytosolic indicators with mobile calcium buffering properties. The speed of the wave was related to pulse application frequency and it was not propagated by calcium induced calcium release. Copyright © 2017 Elsevier B.V. All rights reserved.

Combinatory annotation of cell membrane receptors and signalling pathways of Bombyx mori prothoracic glands

PubMed Central

Moulos, Panagiotis; Samiotaki, Martina; Panayotou, George; Dedos, Skarlatos G.

2016-01-01

The cells of prothoracic glands (PG) are the main site of synthesis and secretion of ecdysteroids, the biochemical products of cholesterol conversion to steroids that shape the morphogenic development of insects. Despite the availability of genome sequences from several insect species and the extensive knowledge of certain signalling pathways that underpin ecdysteroidogenesis, the spectrum of signalling molecules and ecdysteroidogenic cascades is still not fully comprehensive. To fill this gap and obtain the complete list of cell membrane receptors expressed in PG cells, we used combinatory bioinformatic, proteomic and transcriptomic analysis and quantitative PCR to annotate and determine the expression profiles of genes identified as putative cell membrane receptors of the model insect species, Bombyx mori, and subsequently enrich the repertoire of signalling pathways that are present in its PG cells. The genome annotation dataset we report here highlights modules and pathways that may be directly involved in ecdysteroidogenesis and aims to disseminate data and assist other researchers in the discovery of the role of such receptors and their ligands. PMID:27576083

Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells.

PubMed

Liu, Jinxu; Tu, Huiyin; Zhang, Dongze; Zheng, Hong; Li, Yu-Long

2012-10-25

The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Whole-cell patch-clamp results showed that differentiation (9 days) didn't change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na+ currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na+ currents were significantly enhanced. Western blot data showed that the expression of Na+ channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na+ channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na+ channels in cells with action potential was higher than that in cells without action potential. Differentiation induces expression of voltage-gated Na+ channels and action potential generation in NG108-15 cells. A high level of the Na+ channel density is required for differentiation-triggered action potential generation.

Identification of rice cornichon as a possible cargo receptor for the Golgi-localized sodium transporter OsHKT1;3.

PubMed

Rosas-Santiago, Paul; Lagunas-Gómez, Daniel; Barkla, Bronwyn J; Vera-Estrella, Rosario; Lalonde, Sylvie; Jones, Alexander; Frommer, Wolf B; Zimmermannova, Olga; Sychrová, Hana; Pantoja, Omar

2015-05-01

Membrane proteins are synthesized and folded in the endoplasmic reticulum (ER), and continue their path to their site of residence along the secretory pathway. The COPII system has been identified as a key player for selecting and directing the fate of membrane and secretory cargo proteins. Selection of cargo proteins within the COPII vesicles is achieved by cargo receptors. The cornichon cargo receptor belongs to a conserved protein family found in eukaryotes that has been demonstrated to participate in the selection of integral membrane proteins as cargo for their correct targeting. Here it is demonstrated at the cellular level that rice cornichon OsCNIH1 interacts with OsHKT1;3 and, in yeast cells, enables the expression of the sodium transporter to the Golgi apparatus. Physical and functional HKT-cornichon interactions are confirmed by the mating-based split ubiquitin system, bimolecular fluorescence complementation, and Xenopus oocyte and yeast expression systems. The interaction between the two proteins occurs in the ER of plant cells and their co-expression in oocytes leads to the sequestration of the transporter in the ER. In the yeast cornichon mutant erv14, OsHKT1;3 is mistargeted, preventing the toxic effects of sodium transport in the cell observed in wild-type cells or in the erv14 mutant that co-expressed OsHKT1;3 with either OsCNIH1 or Erv14p. Identification and characterization of rice cornichon as a possible cargo receptor opens up the opportunity to improve our knowledge on membrane protein targeting in plant cells. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Changes in protein expression of U937 and Jurkat cells exposed to nanosecond pulsed electric fields

NASA Astrophysics Data System (ADS)

Moen, Erick K.; Roth, Caleb C.; Cerna, Caesar; Estalck, Larry; Wilmink, Gerald; Ibey, Bennett L.

2013-02-01

Application of nanosecond pulsed electric fields (nsPEF) to various biological cell lines has been to shown to cause many diverse effects, including poration of the plasma membrane, depolarization of the mitochondrial membrane, blebbing, apoptosis, and intracellular calcium bursts. The underlying mechanism(s) responsible for these diverse responses are poorly understood. Of specific interest in this paper are the long-term effects of nsPEF on cellular processes, including the regulation of genes and production of proteins. Previous studies have reported transient activation of select signaling pathways involving mitogen-activated protein kinases (MAPKs), protein phosphorylation and downstream gene expression following nsPEF application. We hypothesize that nsPEF represents a unique stimulus that could be used to externally modulate cellular processes. To validate our hypothesis, we performed a series of cuvette-based exposures at 10 and 600ns pulse widths using a custom Blumlien line pulser system. We measured acute changes in the plasma membrane structure using flow cytometry by tracking phosphatidylserine externalization via FITC-Annexin V labeling and poration via propidium iodide uptake. We then compared these results to viability of the cells at 24 hours post exposure using MTT assay and changes in the MAPK family of proteins at 8 hours post-exposure using Luminex assay. By comparing exposures at 10 and 600ns duration, we found that most MAPK family-protein expression increased in Jurkat and U937 cell lines following exposure and compared well with drops in viability and changes in plasma membrane asymmetry. What proved interesting is that some MAPK family proteins (e.g. p53, STAT1), were expressed in one cell line, but not the other. This difference may point to an underlying mechanism for observed difference in cellular sensitivity to nsPEFinduced stresses.

Expression and Activity of Breast Cancer Resistance Protein (BCRP/ABCG2) in Human Distal Lung Epithelial Cells In Vitro.

PubMed

Nickel, Sabrina; Selo, Mohammed Ali; Fallack, Juliane; Clerkin, Caoimhe G; Huwer, Hanno; Schneider-Daum, Nicole; Lehr, Claus-Michael; Ehrhardt, Carsten

2017-12-01

Breast cancer resistance protein (BCRP/ABCG2) has previously been identified with high expression levels in human lung. The subcellular localisation and functional activity of the transporter in lung epithelia, however, remains poorly investigated. The aim of this project was to study BCRP expression and activity in freshly isolated human alveolar epithelial type 2 (AT2) and type 1-like (AT1-like) cells in primary culture, and to compare these findings with data obtained from the NCI-H441 cell line. BCRP expression levels in AT2 and AT1-like cells and in different passages of NCI-H441 cells were determined using q-PCR and immunoblot. Transporter localisation was confirmed by confocal laser scanning microscopy. Efflux and transport studies using the BCRP substrate BODIPY FL prazosin and the inhibitor Ko143 were carried out to assess BCRP activity in the different cell models. BCRP expression decreased during transdifferentiation from AT2 to AT1-like phenotype. Culturing NCI-H441 cells at an air-liquid interface or submersed did not change BCRP abundance, however, BCRP levels increased with passage number. BCRP was localised to the apical membrane and cytosol in NCI-H441 cells. In primary cells, the protein was found predominantly in the nucleus. Functional studies were consistent with expression data. BCRP is differently expressed in AT2 and AT1-like cells with lower abundance and activity in the latter ones. Nuclear BCRP might play a transcriptional role in distal lung epithelium. In NCI-H441 cells, BCRP is expressed in apical cell membranes and its activity is consistent with the localisation pattern.

Loss of Mammal-specific Tectorial Membrane Component Carcinoembryonic Antigen Cell Adhesion Molecule 16 (CEACAM16) Leads to Hearing Impairment at Low and High Frequencies*

PubMed Central

Kammerer, Robert; Rüttiger, Lukas; Riesenberg, Rainer; Schäuble, Constanze; Krupar, Rosemarie; Kamp, Annegret; Sunami, Kishiko; Eisenried, Andreas; Hennenberg, Martin; Grunert, Fritz; Bress, Andreas; Battaglia, Sebastiano; Schrewe, Heinrich; Knipper, Marlies; Schneider, Marlon R.; Zimmermann, Wolfgang

2012-01-01

The vertebrate-restricted carcinoembryonic antigen gene family evolves extremely rapidly. Among their widely expressed members, the mammal-specific, secreted CEACAM16 is exceptionally well conserved and specifically expressed in the inner ear. To elucidate a potential auditory function, we inactivated murine Ceacam16 by homologous recombination. In young Ceacam16−/− mice the hearing threshold for frequencies below 10 kHz and above 22 kHz was raised. This hearing impairment progressed with age. A similar phenotype is observed in hearing-impaired members of Family 1070 with non-syndromic autosomal dominant hearing loss (DFNA4) who carry a missense mutation in CEACAM16. CEACAM16 was found in interdental and Deiters cells and was deposited in the tectorial membrane of the cochlea between postnatal days 12 and 15, when hearing starts in mice. In cochlear sections of Ceacam16−/− mice tectorial membranes were significantly more often stretched out as compared with wild-type mice where they were mostly contracted and detached from the outer hair cells. Homotypic cell sorting observed after ectopic cell surface expression of the carboxyl-terminal immunoglobulin variable-like N2 domain of CEACAM16 indicated that CEACAM16 can interact in trans. Furthermore, Western blot analyses of CEACAM16 under reducing and non-reducing conditions demonstrated oligomerization via unpaired cysteines. Taken together, CEACAM16 can probably form higher order structures with other tectorial membrane proteins such as α-tectorin and β-tectorin and influences the physical properties of the tectorial membrane. Evolution of CEACAM16 might have been an important step for the specialization of the mammalian cochlea, allowing hearing over an extended frequency range. PMID:22544735

DNA probes for monitoring dynamic and transient molecular encounters on live cell membranes

NASA Astrophysics Data System (ADS)

You, Mingxu; Lyu, Yifan; Han, Da; Qiu, Liping; Liu, Qiaoling; Chen, Tao; Sam Wu, Cuichen; Peng, Lu; Zhang, Liqin; Bao, Gang; Tan, Weihong

2017-05-01

Cells interact with the extracellular environment through molecules expressed on the membrane. Disruption of these membrane-bound interactions (or encounters) can result in disease progression. Advances in super-resolution microscopy have allowed membrane encounters to be examined, however, these methods cannot image entire membranes and cannot provide information on the dynamic interactions between membrane-bound molecules. Here, we show a novel DNA probe that can transduce transient membrane encounter events into readable cumulative fluorescence signals. The probe, which translocates from one anchor site to another, mimicking motor proteins, is realized through a toehold-mediated DNA strand displacement reaction. Using this probe, we successfully monitored rapid encounter events of membrane lipid domains using flow cytometry and fluorescence microscopy. Our results show a preference for encounters within the same lipid domains.

Comparison of the canine corneal epithelial cell sheets cultivated from limbal stem cells on canine amniotic membrane, atelocollagen gel, and temperature-responsive culture dish.

PubMed

Nam, Eunryel; Fujita, Naoki; Morita, Maresuke; Tsuzuki, Keiko; Lin, Hsing Yi; Chung, Cheng Shu; Nakagawa, Takayuki; Nishimura, Ryohei

2015-07-01

The current study compared canine corneal epithelial cell sheets cultivated from limbal stem cells on amniotic membrane, atelocollagen gel, and temperature-responsive culture dish. We collected limbal epithelial cells from the intact eyes of beagles and cultivated the cells on denuded canine amniotic membranes, temperature-responsive cell culture labware, and collagen gel with 3T3 feeder cells. Immunofluorescence staining for Ki-67 was used to analyze the capacity of cell proliferation in the sheets. Immunofluorescence staining was also performed for the corneal epithelium-specific marker cytokeratin 3 and putative stem cell markers ABCG2 and p63. Reverse-transcription polymerase chain reaction (RT-PCR) was performed to detect ABCG2 and p63. The growth rates of the cultivated cells, or the times it took them to reach confluency, were different for the three scaffolds. The cultivated sheet on the temperature-responsive dish consisted of 2-3 layers, while those on the collagen gel and on the amniotic membrane consisted of 5-8 layers. The basal layer cells grown on all three scaffolds expressed putative stem cell markers. In real-time RT-PCR analysis, the highest level of p63 was observed in the sheets grown on collagen gel. In this study, the cells cultured on the collagen gel demonstrated a capacity for cell proliferation, and the expressions of stem cells in the sheets suggested that collagen gel is the most suitable carrier for clinical use. © 2014 American College of Veterinary Ophthalmologists.

Activation of AMPK in human fetal membranes alleviates infection-induced expression of pro-inflammatory and pro-labour mediators.

PubMed

Lim, R; Barker, G; Lappas, M

2015-04-01

In non-gestational tissues, the activation of adenosine monophosphate (AMP)-activated kinase (AMPK) is associated with potent anti-inflammatory actions. Infection and/or inflammation, by stimulating pro-inflammatory cytokines and matrix metalloproteinase (MMP)-9, play a central role in the rupture of fetal membranes. However, no studies have examined the role of AMPK in human labour. Fetal membranes, from term and preterm, were obtained from non-labouring and labouring women, and after preterm pre-labour rupture of membranes (PPROM). AMPK activity was assessed by Western blotting of phosphorylated AMPK expression. To determine the effect of AMPK activators on pro-inflammatory cytokines, fetal membranes were pre-treated with AMPK activators then stimulated with bacterial products LPS and flagellin or viral dsDNA analogue poly(I:C). Primary amnion cells were used to determine the effect of AMPK activators on IL-1β-stimulated MMP-9 expression. AMPK activity was decreased with term labour. There was no effect of preterm labour. AMPK activity was also decreased in preterm fetal membranes, in the absence of labour, with PROM compared to intact membranes. AMPK activators AICAR, phenformin and A769662 significantly decreased IL-6 and IL-8 stimulated by LPS, flagellin and poly(I:C). Primary amnion cells treated with AMPK activators significantly decreased IL-1β-induced MMP-9 expression. The decrease in AMPK activity in fetal membranes after spontaneous term labour and PPROM indicates an anti-inflammatory role for AMPK in human labour and delivery. The use of AMPK activators as possible therapeutics for threatened preterm labour would be an exciting future avenue of research. Copyright © 2015 Elsevier Ltd. All rights reserved.

Disruption of Serinc1, which facilitates serine-derived lipid synthesis, fails to alter macrophage function, lymphocyte proliferation or autoimmune disease susceptibility.

PubMed

Chu, Edward P F; Elso, Colleen M; Pollock, Abigail H; Alsayb, May A; Mackin, Leanne; Thomas, Helen E; Kay, Thomas W H; Silveira, Pablo A; Mansell, Ashley S; Gaus, Katharina; Brodnicki, Thomas C

2017-02-01

During immune cell activation, serine-derived lipids such as phosphatidylserine and sphingolipids contribute to the formation of protein signaling complexes within the plasma membrane. Altering lipid composition in the cell membrane can subsequently affect immune cell function and the development of autoimmune disease. Serine incorporator 1 (SERINC1) is a putative carrier protein that facilitates synthesis of serine-derived lipids. To determine if SERINC1 has a role in immune cell function and the development of autoimmunity, we characterized a mouse strain in which a retroviral insertion abolishes expression of the Serinc1 transcript. Expression analyses indicated that the Serinc1 transcript is readily detectable and expressed at relatively high levels in wildtype macrophages and lymphocytes. The ablation of Serinc1 expression in these immune cells, however, did not significantly alter serine-derived lipid composition or affect macrophage function and lymphocyte proliferation. Analyses of Serinc1-deficient mice also indicated that systemic ablation of Serinc1 expression did not affect viability, fertility or autoimmune disease susceptibility. These results suggest that Serinc1 is dispensable for certain immune cell functions and does not contribute to previously reported links between lipid composition in immune cells and autoimmunity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Capacitance measurements of regulated exocytosis in mouse taste cells.

PubMed

Vandenbeuch, Aurelie; Zorec, Robert; Kinnamon, Sue C

2010-11-03

Exocytosis, consisting of the merger of vesicle and plasma membrane, is a common mechanism used by different types of nucleated cells to release their vesicular contents. Taste cells possess vesicles containing various neurotransmitters to communicate with adjacent taste cells and afferent nerve fibers. However, whether these vesicles engage in exocytosis on a stimulus is not known. Since vesicle membrane merger with the plasma membrane is reflected in plasma membrane area fluctuations, we measured membrane capacitance (C(m)), a parameter linearly related to membrane surface area. To investigate whether taste cells undergo regulated exocytosis, we used the compensated tight-seal whole-cell recording technique to monitor depolarization-induced changes in C(m) in the different types of taste cells. To identify taste cell types, mice expressing green fluorescent protein from the TRPM5 promoter or from the GAD67 promoter were used to discriminate type II and type III taste cells, respectively. Moreover, the cell types were also identified by monitoring their voltage-current properties. The results demonstrate that only type III taste cells show significant depolarization-induced increases in C(m), which were correlated to the voltage-activated calcium currents. The results suggest that type III, but neither type II nor type I cells exhibit depolarization-induced regulated exocytosis to release transmitter and activate gustatory afferent nerve fibers.

A putative role for the plasma membrane potential in the control of the expression of the gene encoding the tomato high-affinity potassium transporter HAK5.

PubMed

Nieves-Cordones, Manuel; Miller, Anthony J; Alemán, Fernando; Martínez, Vicente; Rubio, Francisco

2008-12-01

A chimeric CaHAK1-LeHAK5 transporter with only 15 amino acids of CaHAK1 in the N-terminus mediates high-affinity K(+) uptake in yeast cells. Kinetic and expression analyses strongly suggest that LeHAK5 mediates a significant proportion of the high-affinity K(+) uptake shown by K(+)-starved tomato (Solanum lycopersicum) plants. The development of high-affinity K(+) uptake, putatively mediated by LeHAK5, was correlated with increased LeHAK5 mRNA levels and a more negative electrical potential difference across the plasma membrane of root epidermal and cortical cells. However, this increase in high-affinity K(+) uptake was not correlated with the root K(+) content. Thus, (i) growth conditions that result in a hyperpolarized root plasma membrane potential, such as K(+) starvation or growth in the presence of NH(4) (+), but which do not decrease the K(+) content, lead to increased LeHAK5 expression; (ii) the presence of NaCl in the growth solution, which prevents the hyperpolarization induced by K(+) starvation, also prevents LeHAK5 expression. Moreover, once the gene is induced, depolarization of the plasma membrane potential then produces a decrease in the LeHAK5 mRNA. On the basis of these results, we propose that the plant membrane electrical potential plays a role in the regulation of the expression of this gene encoding a high-affinity K(+) transporter.

The effects of copper on Na(+)/K (+)-ATPase and aquaporin expression in two euryhaline invertebrates.

PubMed

Boyle, R T; Oliveira, L F; Bianchini, A; Souza, M M

2013-03-01

We used immunocytochemical and fluorometric techniques to show that gill cells of two marine invertebrates, the crab Neohelice granulata (osmoregulator) and the clam Mesodesma mactroides (osmoconformer), increase the expression of membrane transporters [Na(+)/K(+)-ATPase and aquaporin (AQP1)] after whole-animals exposure (96 h) to sublethal concentrations of copper in water of salinity 30 ppt, when both clams and crabs are isosmotic with respect to the environmental medium. A plausible interpretation of our findings is that this increased expression in membrane transporters may serve as an attempt to ameliorate the deleterious effects of copper on the mechanisms involved in ion and volume regulation in gill cells.

Effect of Leptospira interrogans outer membrane proteins LipL32 on HUVEC.

PubMed

Sun, Zhan; Bao, Lang; Li, DaoKun; Huang, Bi; Wu, Bingting

2010-09-01

Leptospira cause disease through a toxin-mediated process by inducing vascular injury, particularly a small-vessel vasculitis. Breakdown of vessel endothelial cell integrity may increase vessel permeability which is correlated with the changes of tight junction and/or apoptosis in vessel endothelial cells. The specific toxin responsible remains unidentified. In this study, we amplified outer membrane protein LipL32 from the genome of Leptospira interrogans serovar Lai, and it was subcloned in pET32a(+) vector to express thioredoxin(Trx)-LipL32 fusion protein in Escherichia coli BL21(DE3). The protein was expressed and purified, and Trx-LipL32 was administered to culture with human umbilical vein endothelial cells (HUVEC) to elucidate the role of leptospiral outer membrane proteins in vessel endothelial cell. The purified recombinant protein was capable to increase the permeability of HUVECs. And the protein was able to decrease the expression of ZO-1 and induce F-actin in HUVECs display thickening and clustering. Moreover, apoptosis of HUVEC was significantly accelerated. But the fusion partner had no effect in these regards. It is possible that LipL32 is involved in the vessel lesions. Copyright 2010 Elsevier Ltd. All rights reserved.

Concerted regulation of retinal pigment epithelium basement membrane and barrier function by angiocrine factors.

PubMed

Benedicto, Ignacio; Lehmann, Guillermo L; Ginsberg, Michael; Nolan, Daniel J; Bareja, Rohan; Elemento, Olivier; Salfati, Zelda; Alam, Nazia M; Prusky, Glen T; Llanos, Pierre; Rabbany, Sina Y; Maminishkis, Arvydas; Miller, Sheldon S; Rafii, Shahin; Rodriguez-Boulan, Enrique

2017-05-19

The outer blood-retina barrier is established through the coordinated terminal maturation of the retinal pigment epithelium (RPE), fenestrated choroid endothelial cells (ECs) and Bruch's membrane, a highly organized basement membrane that lies between both cell types. Here we study the contribution of choroid ECs to this process by comparing their gene expression profile before (P5) and after (P30) the critical postnatal period when mice acquire mature visual function. Transcriptome analyses show that expression of extracellular matrix-related genes changes dramatically over this period. Co-culture experiments support the existence of a novel regulatory pathway: ECs secrete factors that remodel RPE basement membrane, and integrin receptors sense these changes triggering Rho GTPase signals that modulate RPE tight junctions and enhance RPE barrier function. We anticipate our results will spawn a search for additional roles of choroid ECs in RPE physiology and disease.

Concerted regulation of retinal pigment epithelium basement membrane and barrier function by angiocrine factors

PubMed Central

Benedicto, Ignacio; Lehmann, Guillermo L.; Ginsberg, Michael; Nolan, Daniel J.; Bareja, Rohan; Elemento, Olivier; Salfati, Zelda; Alam, Nazia M.; Prusky, Glen T.; Llanos, Pierre; Rabbany, Sina Y.; Maminishkis, Arvydas; Miller, Sheldon S.; Rafii, Shahin; Rodriguez-Boulan, Enrique

2017-01-01

The outer blood-retina barrier is established through the coordinated terminal maturation of the retinal pigment epithelium (RPE), fenestrated choroid endothelial cells (ECs) and Bruch's membrane, a highly organized basement membrane that lies between both cell types. Here we study the contribution of choroid ECs to this process by comparing their gene expression profile before (P5) and after (P30) the critical postnatal period when mice acquire mature visual function. Transcriptome analyses show that expression of extracellular matrix-related genes changes dramatically over this period. Co-culture experiments support the existence of a novel regulatory pathway: ECs secrete factors that remodel RPE basement membrane, and integrin receptors sense these changes triggering Rho GTPase signals that modulate RPE tight junctions and enhance RPE barrier function. We anticipate our results will spawn a search for additional roles of choroid ECs in RPE physiology and disease. PMID:28524846

BAFF, a Novel Ligand of the Tumor Necrosis Factor Family, Stimulates B Cell Growth

PubMed Central

Schneider, Pascal; MacKay, Fabienne; Steiner, Véronique; Hofmann, Kay; Bodmer, Jean-Luc; Holler, Nils; Ambrose, Christine; Lawton, Pornsri; Bixler, Sarah; Acha-Orbea, Hans; Valmori, Danila; Romero, Pedro; Werner-Favre, Christiane; Zubler, Rudolph H.; Browning, Jeffrey L.; Tschopp, Jürg

1999-01-01

Members of the tumor necrosis factor (TNF) family induce pleiotropic biological responses, including cell growth, differentiation, and even death. Here we describe a novel member of the TNF family, designated BAFF (for B cell activating factor belonging to the TNF family), which is expressed by T cells and dendritic cells. Human BAFF was mapped to chromosome 13q32-34. Membrane-bound BAFF was processed and secreted through the action of a protease whose specificity matches that of the furin family of proprotein convertases. The expression of BAFF receptor appeared to be restricted to B cells. Both membrane-bound and soluble BAFF induced proliferation of anti-immunoglobulin M–stimulated peripheral blood B lymphocytes. Moreover, increased amounts of immunoglobulins were found in supernatants of germinal center–like B cells costimulated with BAFF. These results suggest that BAFF plays an important role as costimulator of B cell proliferation and function. PMID:10359578

Ionizing radiation modulates the surface expression of human leukocyte antigen-G in a human melanoma cell line.

PubMed

Michelin, Severino; Gallegos, Cristina E; Dubner, Diana; Favier, Benoit; Carosella, Edgardo D

2009-12-01

Human leukocyte antigen G (HLA-G) is a nonclassical HLA class I molecule involved in fetus protection from the maternal immune system, transplant tolerance, and viral and tumoral immune escape. Tumor-specific HLA-G expression has been described for a wide variety of malignancies, including melanomas. The aim of this study was to evaluate whether ionizing radiation (IR) could modulate the surface expression of HLA-G1 in a human melanoma cell line that expresses endogenously membrane-bound HLA-G1. For this purpose, cells were exposed to increasing doses of gamma-irradiation (0-20 Gy) and HLA-G1 levels at the plasma membrane were analyzed at different times postirradiation by flow cytometry. HLA-G total expression and the presence of the soluble form of HLA-G1 (sHLA-G1) in the culture medium of irradiated cells were also evaluated. IR was capable of downregulating cell surface and total HLA-G levels, with a concomitant increase of sHLA-G1 in the medium. These results could indicate that gamma-irradiation decreases HLA-G1 surface levels by enhancing the proteolytic cleavage of this molecule.

Hijacked then lost in translation: the plight of the recombinant host cell in membrane protein structural biology projects.

PubMed

Bill, Roslyn M; von der Haar, Tobias

2015-06-01

Membrane protein structural biology is critically dependent upon the supply of high-quality protein. Over the last few years, the value of crystallising biochemically characterised, recombinant targets that incorporate stabilising mutations has been established. Nonetheless, obtaining sufficient yields of many recombinant membrane proteins is still a major challenge. Solutions are now emerging based on an improved understanding of recombinant host cells; as a 'cell factory' each cell is tasked with managing limited resources to simultaneously balance its own growth demands with those imposed by an expression plasmid. This review examines emerging insights into the role of translation and protein folding in defining high-yielding recombinant membrane protein production in a range of host cells. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

The 78 kDa glucose-regulated protein (GRP78/BIP) is expressed on the cell membrane, is released into cell culture medium and is also present in human peripheral circulation.

PubMed

Delpino, Andrea; Castelli, Mauro

2002-01-01

In human rabdomiosarcoma cells (TE671/RD) chronic exposure to 500 nM thapsigargin (a powerful inhibitor of the endoplasmic reticulum Ca2+-ATPases) resulted in the induction of the stress protein GRP78/BIP. Making use of the surface biotinylation method, followed by the isolation of the GRP78 using ATP-agarose affinity chromatography, it was found that a fraction of the thapsigargin-induced GRP78 is expressed on the cell surface. The presence of GRP78 on the membrane of thapsigargin-treated cells was confirmed by fractionation of cell lysates into a soluble and a membrane fraction, followed by Western blot analysis with an anti-GRP78 antibody. It was also found that conspicuous amounts of GRP78 are present in the culture medium collected from thapsigargin-treated cultures. This extracellular GRP78 originates mostly by an active release from intact cells and does not result solely from the leakage of proteins from dead cells. Moreover, small amounts of circulating, free GRP78 and naturally-occurring anti-GRP78 autoantibodies were detected in the peripheral circulation of healthy human individuals.

α–Synuclein and PolyUnsaturated Fatty Acids Promote Clathrin Mediated Endocytosis and Synaptic Vesicle Recycling

PubMed Central

Ben Gedalya, Tziona; Loeb, Virginie; Israeli, Eitan; Altschuler, Yoram; Selkoe, Dennis J.; Sharon, Ronit

2009-01-01

α-Synuclein (αS) is an abundant neuronal cytoplasmic protein implicated in Parkinson’s disease (PD), but its physiological function remains unknown. Consistent with its having structural motifs shared with class A1 apolipoproteins, αS can reversibly associate with membranes and help regulate membrane fatty acid (FA) composition. We previously observed that variations in αS expression level in dopaminergic cultured cells or brains are associated with changes in polyunsaturated fatty acid (PUFA) levels and altered membrane fluidity. We now report that αS acts with PUFAs to enhance the internalization of the membrane-binding dye, FM 1-43. Specifically, αS expression coupled with exposure to physiological levels of certain PUFAs enhanced clathrin-mediated endocytosis in neuronal and non-neuronal cultured cells. Moreover, αS expression and PUFA enhanced basal and evoked synaptic vesicle endocytosis in primary hippocampal cultures of wt and genetically depleted αS mouse brains. We suggest that αS, and PUFAs normally functions in endocytic mechanisms and are specifically involved in synaptic vesicle recycling upon neuronal stimulation. PMID:18980610

Expression of CD133 confers malignant potential by regulating metalloproteinases in human hepatocellular carcinoma.

PubMed

Kohga, Keisuke; Tatsumi, Tomohide; Takehara, Tetsuo; Tsunematsu, Hinako; Shimizu, Satoshi; Yamamoto, Masashi; Sasakawa, Akira; Miyagi, Takuya; Hayashi, Norio

2010-06-01

Although CD133 expression is identified as a cancer stem cell marker of hepatocellular carcinoma (HCC), the detailed characteristics of HCC cells expressing CD133 remain unclear. We examined the malignant characteristics of CD133-expressing HCC cells. CD133-expressing cells could be detected with low frequency in 5 HCC tissues. We derived two different HCC cell lines by (1) transfection of CD133 siRNA in PLC/PRF/5 cells in (CD133si-PLC/PRF/5), and (2) by a magnetic cell sorting method that allowed to divide Huh7 cells into two CD133 positive (+) and negative (-) groups. CD133 knockdown in PLC/PRF/5 cells resulted in a decrease of the mRNA and protein expressions of matrix metalloproteinase (MMP)-2 and a disintegrin and metalloproteinase (ADAM)9. We next examined the malignant characteristics related to decreasing MMP-2 and ADAM9 in HCC cells. In CD133si-PLC/PRF/5 cells and CD133- Huh7 cells, invasiveness and vascular endothelial growth factor (VEGF) production, which are both related to the activity of MMP-2, were inhibited compared CD133-expressing HCC cells. We previously demonstrated that ADAM9 protease plays critical roles in the shedding of MHC class I-related chain A (MICA) which regulates the sensitivity of tumor cells to natural killer cells (NK). Decreasing ADAM9 expression in CD133si-PLC/PRF/5 cells and CD133- Huh7 cells resulted in an increase in membrane-bound MICA and a decrease in soluble MICA production. Both CD133si-PLC/PRF/5 cells and CD133- Huh7 cells were susceptible to NK activity, depending on the expression levels of membrane-bound MICA, but CD133-expressing HCC cells were not. These results demonstrate that CD133 expression in HCC cells confers malignant potential which may contribute to the survival of HCC cells. Copyright 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Functional expression of Schizosaccharomyces pombe Vba2p in the vacuolar membrane of Saccharomyces cerevisiae.

PubMed

Pongcharoen, Pongsanat; Kawano-Kawada, Miyuki; Iwaki, Tomoko; Sugimoto, Naoko; Sekito, Takayuki; Akiyama, Koichi; Takegawa, Kaoru; Kakinuma, Yoshimi

2013-01-01

A vacuolar membrane protein, Vba2p of Schizosaccharomyces pombe, is involved in basic amino acid uptake by intact cells. Here we found evidence that Vba2p mediated ATP-dependent lysine uptake by vacuolar membrane vesicles of Saccharomyces cerevisiae. Vba2p was also responsible for quinidine sensitivity, and the addition of lysine improved cell growth on quinidine-containing media. These findings should be useful for further characterization of Vba2p.

G Protein-Coupled Estrogen Receptor (GPER) Expression in Normal and Abnormal Endometrium

PubMed Central

Lessey, Bruce A.; Taylor, Robert N.; Wang, Wei; Bagchi, Milan K.; Yuan, Lingwen; Scotchie, Jessica; Fritz, Marc A.; Young, Steven L.

2012-01-01

Rapid estrogen effects are mediated by membrane receptors, and evidence suggests a role for both a membrane-associated form of estrogen receptor alpha (ESR1; ERα) and G-protein coupled receptor 30 (GPER; GPR30). Considering estrogen’s importance in endometrial physiology and endometriosis pathophysiology, we hypothesized that GPER could be involved in both cyclic changes in endometrial estrogen action and that aberrant expression might be seen in the eutopic endometrium of women with endometriosis. Using real-time reverse transcriptase–polymerase chain reaction (RT-PCR) and immunohistochemical analysis of normal endometrium, endometrial samples demonstrated cycle-regulated expression of GPER, with maximal expression in the proliferative phase. Eutopic and ectopic endometrium from women with endometriosis overexpressed GPER as compared to eutopic endometrium of normal participants. Ishikawa cells, an adenocarcinoma cell line, expressed GPER, with increased expression upon treatment with estrogen or an ESR1 agonist, but not with a GPER-specific agonist. Decreased expression was seen in Ishikawa cells stably transfected with progesterone receptor A. Together, these data suggest that normal endometrial GPER expression is cyclic and regulated by nuclear estrogen and progesterone receptors, while expression is dysregulated in endometriosis. PMID:22378861

G protein-coupled estrogen receptor (GPER) expression in normal and abnormal endometrium.

PubMed

Plante, Beth J; Lessey, Bruce A; Taylor, Robert N; Wang, Wei; Bagchi, Milan K; Yuan, Lingwen; Scotchie, Jessica; Fritz, Marc A; Young, Steven L

2012-07-01

Rapid estrogen effects are mediated by membrane receptors, and evidence suggests a role for both a membrane-associated form of estrogen receptor alpha (ESR1; ERα) and G-protein coupled receptor 30 (GPER; GPR30). Considering estrogen's importance in endometrial physiology and endometriosis pathophysiology, we hypothesized that GPER could be involved in both cyclic changes in endometrial estrogen action and that aberrant expression might be seen in the eutopic endometrium of women with endometriosis. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemical analysis of normal endometrium, endometrial samples demonstrated cycle-regulated expression of GPER, with maximal expression in the proliferative phase. Eutopic and ectopic endometrium from women with endometriosis overexpressed GPER as compared to eutopic endometrium of normal participants. Ishikawa cells, an adenocarcinoma cell line, expressed GPER, with increased expression upon treatment with estrogen or an ESR1 agonist, but not with a GPER-specific agonist. Decreased expression was seen in Ishikawa cells stably transfected with progesterone receptor A. Together, these data suggest that normal endometrial GPER expression is cyclic and regulated by nuclear estrogen and progesterone receptors, while expression is dysregulated in endometriosis.

Expression and distribution of transient receptor potential (TRP) channels in bladder epithelium.

PubMed

Yu, Weiqun; Hill, Warren G; Apodaca, Gerard; Zeidel, Mark L

2011-01-01

The urothelium is proposed to be a sensory tissue that responds to mechanical stress by undergoing dynamic membrane trafficking and neurotransmitter release; however, the molecular basis of this function is poorly understood. Transient receptor potential (TRP) channels are ideal candidates to fulfill such a role as they can sense changes in temperature, osmolarity, and mechanical stimuli, and several are reported to be expressed in the bladder epithelium. However, their complete expression profile is unknown and their cellular localization is largely undefined. We analyzed expression of all 33 TRP family members in mouse bladder and urothelium by RT-PCR and found 22 specifically expressed in the urothelium. Of the latter, 10 were chosen for closer investigation based on their known mechanosensory or membrane trafficking functions in other cell types. Western blots confirmed urothelial expression of TRPC1, TRPC4, TRPV1, TRPV2, TRPV4, TRPM4, TRPM7, TRPML1, and polycystins 1 and 2 (PKD1 and PKD2) proteins. We further defined the cellular and subcellular localization of all 10 TRP channels. TRPV2 and TRPM4 were prominently localized to the umbrella cell apical membrane, while TRPC4 and TRPV4 were identified on their abluminal surfaces. TRPC1, TRPM7, and TRPML1 were localized to the cytoplasm, while PKD1 and PKD2 were expressed on the apical and basolateral membranes of umbrella cells as well as in the cytoplasm. The cellular location of TRPV1 in the bladder has been debated, but colocalization with neuronal marker calcitonin gene-related peptide indicated clearly that it is present on afferent neurons that extend into the urothelium, but may not be expressed by the urothelium itself. These findings are consistent with the hypothesis that the urothelium acts as a sentinel and by expressing multiple TRP channels it is likely it can detect and presumably respond to a diversity of external stimuli and suggest that it plays an important role in urothelial signal transduction.

Segregation of Two Spectrin Isoforms: Polarized Membrane-binding Sites Direct Polarized Membrane Skeleton Assembly

PubMed Central

Dubreuil, Ronald R.; Maddux, Pratumtip Boontrakulpoontawee; Grushko, Tanya A.; Macvicar, Gary R.

1997-01-01

Spectrin isoforms are often segregated within specialized plasma membrane subdomains where they are thought to contribute to the development of cell surface polarity. It was previously shown that ankyrin and β spectrin are recruited to sites of cell–cell contact in Drosophila S2 cells expressing the homophilic adhesion molecule neuroglian. Here, we show that neuroglian has no apparent effect on a second spectrin isoform (αβH), which is constitutively associated with the plasma membrane in S2 cells. Another membrane marker, the Na,K-ATPase, codistributes with ankyrin and αβ spectrin at sites of neuroglian-mediated contact. The distributions of these markers in epithelial cells in vivo are consistent with the order of events observed in S2 cells. Neuroglian, ankyrin, αβ spectrin, and the Na,K-ATPase colocalize at the lateral domain of salivary gland cells. In contrast, αβH spectrin is sorted to the apical domain of salivary gland and somatic follicle cells. Thus, the two spectrin isoforms respond independently to positional cues at the cell surface: in one case an apically sorted receptor and in the other case a locally activated cell–cell adhesion molecule. The results support a model in which the membrane skeleton behaves as a transducer of positional information within cells. PMID:9348534

Isotropic Versus Bipolar Functionalized Biomimetic Artificial Basement Membranes and Their Evaluation in Long-Term Human Cell Co-Culture.

PubMed

Rossi, Angela; Wistlich, Laura; Heffels, Karl-Heinz; Walles, Heike; Groll, Jürgen

2016-08-01

In addition to dividing tissues into compartments, basement membranes are crucial as cell substrates and to regulate cellular behavior. The development of artificial basement membranes is indispensable for the ultimate formation of functional engineered tissues; however, pose a challenge due to their complex structure. Herein, biodegradable electrospun polyester meshes are presented, exhibiting isotropic or bipolar bioactivation as a biomimetic and biofunctional model of the natural basement membrane. In a one-step preparation process, reactive star-shaped prepolymer additives, which generate a hydrophilic fiber surface, are electrospun with cell-adhesion-mediating peptides, derived from major components of the basement membrane. Human skin cells adhere to the functionalized meshes, and long-term co-culture experiments confirm that the artificial basement membranes recapitulate and preserve tissue specific functions. Several layers of immortalized human keratinocytes grow on the membranes, differentiating toward the surface and expressing typical epithelial markers. Fibroblasts migrate into the reticular lamina mimicking part of the mesh. Both cells types begin to produce extracellular matrix proteins and to remodel the initial membrane. It is shown at the example of skin that the artificial basement membrane design provokes biomimetic responses of different cell types and can thus be used as basis for the future development of basement membrane containing tissues. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Anti-inflammatory Drug Indomethacin Alters Nanoclustering in Synthetic and Cell Plasma Membranes*

PubMed Central

Zhou, Yong; Plowman, Sarah J.; Lichtenberger, Lenard M.; Hancock, John F.

2010-01-01

The nonsteroidal anti-inflammatory drug indomethacin exhibits diverse biological effects, many of which have no clear molecular mechanism. Membrane-bound receptors and enzymes are sensitive to their phospholipid microenvironment. Amphipathic indomethacin could therefore potentially modulate cell signaling by changing membrane properties. Here we examined the effect of indomethacin on membrane lateral heterogeneity. Fluorescence lifetime imaging of cells expressing lipid-anchored probes revealed that treatment of BHK cells with therapeutic levels of indomethacin enhances cholesterol-dependent nanoclustering, but not cholesterol-independent nanoclustering. Immuno-electron microscopy and quantitative spatial mapping of intact plasma membrane sheets similarly showed a selective effect of indomethacin on promoting cholesterol-dependent, but not cholesterol-independent, nanoclustering. To further evaluate the biophysical effects of indomethacin, we measured fluorescence polarization of the phase-sensitive probe Laurdan and FRET between phase-partitioning probes in model bilayers. Therapeutic levels of indomethacin enhanced phase seperation in DPPC/DOPC/Chol (1:1:1) and DPPC/Chol membranes in a temperature-dependent manner, but had minimal effect on the phase behavior of pure DOPC at any temperature. Taken together, the imaging results on intact epithelial cells and the biophysical assays of model membranes suggest that indomethacin can enhance phase separation and stabilize cholesterol-dependent nanoclusters in biological membranes. These effects on membrane lateral heterogeneity may have significant consequences for cell signaling cascades that are assembled on the plasma membrane. PMID:20826816

Enhanced functional expression of aquaporin Z via fusion of in situ cleavable leader peptides in Escherichia coli cell-free system.

PubMed

Zhang, Xu; Lian, Jiazhang; Kai, Lei; Huang, Lei; Cen, Peilin; Xu, Zhinan

2014-02-05

Aquaporin Z (AqpZ) is a water channel protein from Escherichia coli and has attracted many attentions to develop the biomimetic water filtration technology. Cell-free protein synthesis (CFPS) system, one of the most complex multi-enzymatic systems, has the ability of producing the integral membrane protein in vitro. To enhance the synthesis of AqpZ in E. coli cell-free system, several natural leader peptides were respectively fused at the N-terminus and were verified to enhance the expression level significantly. Moreover, the supplementation of detergents or liposome could activate leader peptidase from the cell-free extract and provide hydrophobic environment for proper folding of AqpZ. Thus, the release of mature AqpZ via the in situ removal of leader peptide was achieved, with a specific water transport activity of (2.1 ± 0.1) × 10⁻¹⁴ cm³ s⁻¹ monomer⁻¹. Using this in situ removable leader peptide strategy, the transcription-translation, leader sequence cleavage and membrane protein folding were integrated into a simple process in the cell-free system, providing a convenient approach to enhance the expression of target proteins, especially those membrane proteins difficult to achieve. Copyright © 2013 Elsevier Inc. All rights reserved.

A Stable Human-Cell System Overexpressing Cystic Fibrosis Transmembrane Conductance Regulator Recombinant Protein at the Cell Surface

PubMed Central

Dai, Qun; Aleksandrov, Andrei A.; Bajrami, Bekim; Diego, Pamela Ann; Wu, Xing; Ray, Marjorie; Naren, Anjaparavanda P.; Riordan, John R.; Yao, Xudong; DeLucas, Lawrence J.; Urbatsch, Ina L.; Kappes, John C.

2015-01-01

Recent human clinical trials results demonstrated successful treatment for certain genetic forms of cystic fibrosis (CF). To extend treatment opportunities to those afflicted with other genetic forms of CF disease, structural and biophysical characterization of CF transmembrane conductance regulator (CFTR) is urgently needed. In this study, CFTR was modified with various tags, including a His10 purification tag, the SUMOstar (SUMO*) domain, an extracellular FLAG epitope, or an enhanced green fluorescent protein (EGFP), each alone or in various combinations. Expressed in HEK293 cells, recombinant CFTR proteins underwent complex glycosylation, compartmentalized with the plasma membrane, and exhibited regulated chloride-channel activity with only modest alterations in channel conductance and gating kinetics. Surface CFTR expression level was enhanced by the presence of SUMO* on the N-terminus. Quantitative mass-spectrometric analysis indicated approximately 10% of the total recombinant CFTR (SUMO*-CFTRFLAG-EGFP) localized to the plasma membrane. Trial purification using dodecylmaltoside for membrane protein extraction reproducibly recovered 178 ± 56 μg SUMO*-CFTRFLAG-EGFP per billion cells at 80% purity. Fluorescence size-exclusion chromatography indicated purified CFTR was monodisperse. These findings demonstrate a stable mammalian cell expression system capable of producing human CFTR of sufficient quality and quantity to augment futrure CF drug discovery efforts, including biophysical and structural studies. PMID:25577540

Involvement of glycosphingolipid-enriched lipid rafts in inflammatory responses.

PubMed

Iwabuchi, Kazuhisa

2015-01-01

Glycosphingolipids (GSLs) are membrane components consisting of hydrophobic ceramide and hydrophilic sugar moieties. GSLs cluster with cholesterol in cell membranes to form GSL-enriched lipid rafts. Biochemical analyses have demonstrated that GSL-enriched lipid rafts contain several kinds of transducer molecules, including Src family kinases. Among the GSLs, lactosylceramide (LacCer, CDw17) can bind to various microorganisms, is highly expressed on the plasma membranes of human phagocytes, and forms lipid rafts containing the Src family tyrosine kinase Lyn. LacCer-enriched lipid rafts mediate immunological and inflammatory reactions, including superoxide generation, chemotaxis, and non-opsonic phagocytosis. Therefore, LacCer-enriched membrane microdomains are thought to function as pattern recognition receptors (PRRs), which recognize pathogen-associated molecular patterns (PAMPs) expressed on microorganisms. LacCer also serves as a signal transduction molecule for functions mediated by CD11b/CD18-integrin (αM/β2-integrin, CR3, Mac-1), as well as being associated with several key cellular processes. LacCer recruits PCKα/ε and phospholipase A2 to stimulate PECAM-1 expression in human monocytes and their adhesion to endothelial cells, as well as regulating β1-integrin clustering and endocytosis on cell surfaces. This review describes the organizational and inflammation-related functions of LacCer-enriched lipid rafts.

Boosting the signal: Endothelial inward rectifier K+ channels.

PubMed

Jackson, William F

2017-04-01

Endothelial cells express a diverse array of ion channels including members of the strong inward rectifier family composed of K IR 2 subunits. These two-membrane spanning domain channels are modulated by their lipid environment, and exist in macromolecular signaling complexes with receptors, protein kinases and other ion channels. Inward rectifier K + channel (K IR ) currents display a region of negative slope conductance at membrane potentials positive to the K + equilibrium potential that allows outward current through the channels to be activated by membrane hyperpolarization, permitting K IR to amplify hyperpolarization induced by other K + channels and ion transporters. Increases in extracellular K + concentration activate K IR allowing them to sense extracellular K + concentration and transduce this change into membrane hyperpolarization. These properties position K IR to participate in the mechanism of action of hyperpolarizing vasodilators and contribute to cell-cell conduction of hyperpolarization along the wall of microvessels. The expression of K IR in capillaries in electrically active tissues may allow K IR to sense extracellular K + , contributing to functional hyperemia. Understanding the regulation of expression and function of microvascular endothelial K IR will improve our understanding of the control of blood flow in the microcirculation in health and disease and may provide new targets for the development of therapeutics in the future. © 2016 John Wiley & Sons Ltd.

Expression of TM4SF10, a Claudin/EMP/PMP22 family cell junction protein, during mouse kidney development and podocyte differentiation.

PubMed

Bruggeman, Leslie A; Martinka, Scott; Simske, Jeffrey S

2007-02-01

Cell junctions in the nephron are highly specialized to perform specific and distinct filtration and reabsorption functions. The mature kidney forms complex cell junctions including slit diaphragms that prevent the passage of serum proteins into the filtrate, and tubule cell junctions that regulate specific paracellular ion reuptake. We have investigated the expression of TM4SF10 (Trans-Membrane tetra(4)-Span Family 10) in mouse kidneys. TM4SF10 is the vertebrate orthologue of Caenorhabditis elegans VAB-9, a tetraspan adherens junction protein in the PMP22/EMP/Claudin family of proteins. We found that TM4SF10 localizes at the basal-most region of podocyte precursors before the capillary loop stage, at some tubule precursors, and at the ureteric bud junction with S-shaped bodies. Overall expression of TM4SF10 peaked at postnatal day 4 and was virtually absent in adult kidneys. The very limited expression of TM4SF10 protein that persisted into adulthood was restricted to a few tubule segments but remained localized to the basal region of lateral membranes. In undifferentiated cultured podocytes, TM4SF10 localized to the perinuclear region and translocated to the cell membrane after Cadherin appearance at cell-cell contacts. TM4SF10 colocalized with ZO1 and p120ctn in undifferentiated confluent podocytes and also colocalized with the tips of actin filaments at cell contacts. Upon differentiation of cultured podocytes, TM4SF10 protein disappeared from cell contacts and expression ceased. These results suggest that TM4SF10 functions during differentiation of podocytes and may participate in the maturation of cell junctions from simple adherens junctions to elaborate slit diaphragms. TM4SF10 may define a new class of Claudin-like proteins that function during junctional development.

A Proteomic View at the Biochemistry of Syntrophic Butyrate Oxidation in Syntrophomonas wolfei

PubMed Central

Schmidt, Alexander; Müller, Nicolai; Schink, Bernhard; Schleheck, David

2013-01-01

In syntrophic conversion of butyrate to methane and CO2, butyrate is oxidized to acetate by secondary fermenting bacteria such as Syntrophomonas wolfei in close cooperation with methanogenic partner organisms, e.g., Methanospirillum hungatei. This process involves an energetically unfavourable shift of electrons from the level of butyryl-CoA oxidation to the substantially lower redox potential of proton and/or CO2 reduction, in order to transfer these electrons to the methanogenic partner via hydrogen and/or formate. In the present study, all prominent membrane-bound and soluble proteins expressed in S. wolfei specifically during syntrophic growth with butyrate, in comparison to pure-culture growth with crotonate, were examined by one- and two-dimensional gel electrophoresis, and identified by peptide fingerprinting-mass spectrometry. A membrane-bound, externally oriented, quinone-linked formate dehydrogenase complex was expressed at high level specifically during syntrophic butyrate oxidation, comprising a selenocystein-linked catalytic subunit with a membrane-translocation pathway signal (TAT), a membrane-bound iron-sulfur subunit, and a membrane-bound cytochrome. Soluble hydrogenases were expressed at high levels specifically during growth with crotonate. The results were confirmed by native protein gel electrophoresis, by formate dehydrogenase and hydrogenase-activity staining, and by analysis of formate dehydrogenase and hydrogenase activities in intact cells and cell extracts. Furthermore, constitutive expression of a membrane-bound, internally oriented iron-sulfur oxidoreductase (DUF224) was confirmed, together with expression of soluble electron-transfer flavoproteins (EtfAB) and two previously identified butyryl-CoA dehydrogenases. Our findings allow to depict an electron flow scheme for syntrophic butyrate oxidation in S. wolfei. Electrons derived from butyryl-CoA are transferred through a membrane-bound EtfAB:quinone oxidoreductase (DUF224) to a menaquinone cycle and further via a b-type cytochrome to an externally oriented formate dehydrogenase. Hence, an ATP hydrolysis-driven proton-motive force across the cytoplasmatic membrane would provide the energy input for the electron potential shift necessary for formate formation. PMID:23468890

Imaging Ca2+-triggered exocytosis of single secretory granules on plasma membrane lawns from neuroendocrine cells.

PubMed

Lang, Thorsten

2008-01-01

This cell-free assay for exocytosis is particularly useful when spatial information about exocytotic sites and biochemical access to the plasma membrane within less than a minute is required. It is based on the study of plasma membrane lawns from secretory cells exhibiting secretory granules filled with neuropeptide Y-green fluorescent protein (NPY-GFP). The sample is prepared by subjecting NPY-GFP-expressing cells to a brief ultrasound pulse, leaving behind a basal, flat plasma membrane with fluorescent attached secretory organelles. These sheets can then be incubated in defined solutions with the benefit that complete solution changes can be achieved in less than 1 min. Individual secretory granules are monitored in the docked state and during exocytosis by video microscopy.

Biphasic voltage-dependent inactivation of human NaV 1.3, 1.6 and 1.7 Na+ channels expressed in rodent insulin-secreting cells.

PubMed

Godazgar, Mahdieh; Zhang, Quan; Chibalina, Margarita V; Rorsman, Patrik

2018-05-01

Na + current inactivation is biphasic in insulin-secreting cells, proceeding with two voltage dependences that are half-maximal at ∼-100 mV and -60 mV. Inactivation of voltage-gated Na + (Na V ) channels occurs at ∼30 mV more negative voltages in insulin-secreting Ins1 and primary β-cells than in HEK, CHO or glucagon-secreting αTC1-6 cells. The difference in inactivation between Ins1 and non-β-cells persists in the inside-out patch configuration, discounting an involvement of a diffusible factor. In Ins1 cells and primary β-cells, but not in HEK cells, inactivation of a single Na V subtype is biphasic and follows two voltage dependences separated by 30-40 mV. We propose that Na V channels adopt different inactivation behaviours depending on the local membrane environment. Pancreatic β-cells are equipped with voltage-gated Na + channels that undergo biphasic voltage-dependent steady-state inactivation. A small Na + current component (10-15%) inactivates over physiological membrane potentials and contributes to action potential firing. However, the major Na + channel component is completely inactivated at -90 to -80 mV and is therefore inactive in the β-cell. It has been proposed that the biphasic inactivation reflects the contribution of different Na V α-subunits. We tested this possibility by expression of TTX-resistant variants of the Na V subunits found in β-cells (Na V 1.3, Na V 1.6 and Na V 1.7) in insulin-secreting Ins1 cells and in non-β-cells (including HEK and CHO cells). We found that all Na V subunits inactivated at 20-30 mV more negative membrane potentials in Ins1 cells than in HEK or CHO cells. The more negative inactivation in Ins1 cells does not involve a diffusible intracellular factor because the difference between Ins1 and CHO persisted after excision of the membrane. Na V 1.7 inactivated at 15--20 mV more negative membrane potentials than Na V 1.3 and Na V 1.6 in Ins1 cells but this small difference is insufficient to solely explain the biphasic inactivation in Ins1 cells. In Ins1 cells, but never in the other cell types, widely different components of Na V inactivation (separated by 30 mV) were also observed following expression of a single type of Na V α-subunit. The more positive component exhibited a voltage dependence of inactivation similar to that found in HEK and CHO cells. We propose that biphasic Na V inactivation in insulin-secreting cells reflects insertion of channels in membrane domains that differ with regard to lipid and/or membrane protein composition. © 2018 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Deciphering membrane-associated molecular processes in target tissue of autoimmune uveitis by label-free quantitative mass spectrometry.

PubMed

Hauck, Stefanie M; Dietter, Johannes; Kramer, Roxane L; Hofmaier, Florian; Zipplies, Johanna K; Amann, Barbara; Feuchtinger, Annette; Deeg, Cornelia A; Ueffing, Marius

2010-10-01

Autoimmune uveitis is a blinding disease presenting with autoantibodies against eye-specific proteins as well as autoagressive T cells invading and attacking the immune-privileged target tissue retina. The molecular events enabling T cells to invade and attack the tissue have remained elusive. Changes in membrane protein expression patterns between diseased and healthy stages are especially interesting because initiating events of disease will most likely occur at membranes. Since disease progression is accompanied with a break-down of the blood-retinal barrier, serum-derived proteins mask the potential target tissue-related changes. To overcome this limitation, we used membrane-enriched fractions derived from retinas of the only available spontaneous animal model for the disease equine recurrent uveitis, and compared expression levels by a label-free LC-MSMS-based strategy to healthy control samples. We could readily identify a total of 893 equine proteins with 57% attributed to the Gene Ontology project term "membrane." Of these, 179 proteins were found differentially expressed in equine recurrent uveitis tissue. Pathway enrichment analyses indicated an increase in proteins related to antigen processing and presentation, TNF receptor signaling, integrin cell surface interactions and focal adhesions. Additionally, loss of retina-specific proteins reflecting decrease of vision was observed as well as an increase in Müller glial cell-specific proteins indicating glial reactivity. Selected protein candidates (caveolin 1, integrin alpha 1 and focal adhesion kinase) were validated by immunohistochemistry and tissue staining pattern pointed to a significant increase of these proteins at the level of the outer limiting membrane which is part of the outer blood-retinal barrier. Taken together, the membrane enrichment in combination with LC-MSMS-based label-free quantification greatly increased the sensitivity of the comparative tissue profiling and resulted in detection of novel molecular pathways related to equine recurrent uveitis.

Reproductive Organ and Vascular Specific Promoter of the Rice Plasma Membrane Ca2+ATPase Mediates Environmental Stress Responses in Plants

PubMed Central

Huda, Kazi Md. Kamrul; Banu, Mst. Sufara Akhter; Pathi, Krishna Mohan; Tuteja, Narendra

2013-01-01

Background Plasma membrane Ca2+ATPase is a transport protein in the plasma membrane of cells and helps in removal of calcium (Ca2+) from the cell, hence regulating Ca2+ level within cells. Though plant Ca2+ATPases have been shown to be involved in plant stress responses but their promoter regions have not been well studied. Results The 1478 bp promoter sequence of rice plasma membrane Ca2+ATPase contains cis-acting elements responsive to stresses and plant hormones. To identify the functional region, serial deletions of the promoter were fused with the GUS sequence and four constructs were obtained. These were differentially activated under NaCl, PEG cold, methyl viologen, abscisic acid and methyl jasmonate treatments. We demonstrated that the rice plasma membrane Ca2+ATPase promoter is responsible for vascular-specific and multiple stress-inducible gene expression. Only full-length promoter showed specific GUS expression under stress conditions in floral parts. High GUS activity was observed in roots with all the promoter constructs. The −1478 to −886 bp flanking region responded well upon treatment with salt and drought. Only the full-length promoter presented cold-induced GUS expression in leaves, while in shoots slight expression was observed for −1210 and −886 bp flanking region. The −1210 bp deletion significantly responded to exogenous methyl viologen and abscisic acid induction. The −1210 and −886 bp flanking region resulted in increased GUS activity in leaves under methyl jasmonate treatments, whereas in shoots the −886 bp and −519 bp deletion gave higher expression. Salicylic acid failed to induce GUS activities in leaves for all the constructs. Conclusions The rice plasma membrane Ca2+ATPase promoter is a reproductive organ-specific as well as vascular-specific. This promoter contains drought, salt, cold, methyl viologen, abscisic acid and methyl jasmonate related cis-elements, which regulated gene expression. Overall, the tissue-specificity and inducible nature of this promoter could grant wide applicability in plant biotechnology. PMID:23469243

Residues within the myristoylation motif determine intracellular targeting of the neuronal Ca2+ sensor protein KChIP1 to post-ER transport vesicles and traffic of Kv4 K+ channels.

PubMed

O'Callaghan, Dermott W; Hasdemir, Burcu; Leighton, Mark; Burgoyne, Robert D

2003-12-01

KChIPs (K+ channel interacting proteins) regulate the function of A-type Kv4 potassium channels by modifying channel properties and by increasing their cell surface expression. We have explored factors affecting the localisation of Kv4.2 and the targeting of KChIP1 and other NCS proteins by using GFP-variant fusion proteins expressed in HeLa cells. ECFP-Kv4.2 expressed alone was not retained in the ER but reached the Golgi complex. In cells co-expressing ECFP-Kv4.2 and KChIP1-EYFP, the two proteins were co-localised and were mainly present on the plasma membrane. When KChIP1-EYFP was expressed alone it was instead targeted to punctate structures. This was distinct from the localisation of the NCS proteins NCS-1 and hippocalcin, which were targeted to the trans-Golgi network (TGN) and plasma membrane. The membrane localisation of each NCS protein required myristoylation and minimal myristoylation motifs of hippocalcin or KChIP1 were sufficient to target fusion proteins to either TGN/plasma membrane or to punctate structures. The existence of targeting information within the N-terminal motifs was confirmed by mutagenesis of residues corresponding to three conserved basic amino acids in hippocalcin and NCS-1 at positions 3, 7 and 9. Residues at these positions determined intracellular targeting to the different organelles. Myristoylation and correct targeting of KChIP1 was required for the efficient traffic of ECFP-Kv4.2 to the plasma membrane. Expression of KChIP1(1-11)-EYFP resulted in the formation of enlarged structures that were positive for ERGIC-53 and beta-COP. ECFP-Kv4.2 was also accumulated in these structures suggesting that KChIP1(1-11)-EYFP inhibited traffic out of the ERGIC. We suggest that KChIP1 is targeted by its myristoylation motif to post-ER transport vesicles where it could interact with and regulate the traffic of Kv4 channels to the plasma membrane under the influence of localised Ca2+ signals.

Mutation of the Membrane-Associated M1 Protease APM1 Results in Distinct Embryonic and Seedling Developmental Defects in Arabidopsis[C][W

PubMed Central

Peer, Wendy Ann; Hosein, Fazeeda N.; Bandyopadhyay, Anindita; Makam, Srinivas N.; Otegui, Marisa S.; Lee, Gil-Je; Blakeslee, Joshua J.; Cheng, Yan; Titapiwatanakun, Boosaree; Yakubov, Bahktiyor; Bangari, Bharat; Murphy, Angus S.

2009-01-01

Aminopeptidase M1 (APM1), a single copy gene in Arabidopsis thaliana, encodes a metallopeptidase originally identified via its affinity for, and hydrolysis of, the auxin transport inhibitor 1-naphthylphthalamic acid (NPA). Mutations in this gene result in haploinsufficiency. Loss-of-function mutants show irregular, uncoordinated cell divisions throughout embryogenesis, affecting the shape and number of cotyledons and the hypophysis, and is seedling lethal at 5 d after germination due to root growth arrest. Quiescent center and cell cycle markers show no signals in apm1-1 knockdown mutants, and the ground tissue specifiers SHORTROOT and SCARECROW are misexpressed or mislocalized. apm1 mutants have multiple, fused cotyledons and hypocotyls with enlarged epidermal cells with cell adhesion defects. apm1 alleles show defects in gravitropism and auxin transport. Gravistimulation decreases APM1 expression in auxin-accumulating root epidermal cells, and auxin treatment increases expression in the stele. On sucrose gradients, APM1 occurs in unique light membrane fractions. APM1 localizes at the margins of Golgi cisternae, plasma membrane, select multivesicular bodies, tonoplast, dense intravacuolar bodies, and maturing metaxylem cells. APM1 associates with brefeldin A–sensitive endomembrane structures and the plasma membrane in cortical and epidermal cells. The auxin-related phenotypes and mislocalization of auxin efflux proteins in apm1 are consistent with biochemical interactions between APM1 and NPA. PMID:19531600

Membrane expression of MRP-1, but not MRP-1 splicing or Pgp expression, predicts survival in patients with ESFT

PubMed Central

Roundhill, E; Burchill, S

2013-01-01

Background: Primary Ewing's sarcoma family of tumours (ESFTs) may respond to chemotherapy, although many patients experience subsequent disease recurrence and relapse. The survival of ESFT cells following chemotherapy has been attributed to the development of resistant disease, possibly through the expression of ABC transporter proteins. Methods: MRP-1 and Pgp mRNA and protein expression in primary ESFTs was determined by quantitative reverse-transcriptase PCR (RT-qPCR) and immunohistochemistry, respectively, and alternative splicing of MRP-1 by RT-PCR. Results: We observed MRP-1 protein expression in 92% (43 out of 47) of primary ESFTs, and cell membrane MRP-1 was highly predictive of both overall survival (P<0.0001) and event-free survival (P<0.0001). Alternative splicing of MRP-1 was detected in primary ESFTs, although the pattern of splicing variants was not predictive of patient outcome, with the exception of loss of exon 9 in six patients, which predicted relapse (P=0.041). Pgp protein was detected in 6% (38 out of 44) of primary ESFTs and was not associated with patient survival. Conclusion: For the first time we have established that cell membrane expression of MRP-1 or loss of exon 9 is predictive of outcome but not the number of splicing events or expression of Pgp, and both may be valuable factors for the stratification of patients for more intensive therapy. PMID:23799853

N-ethylmaleimide-sensitive factor interacts with the serotonin transporter and modulates its trafficking: implications for pathophysiology in autism

PubMed Central

2014-01-01

Background Changes in serotonin transporter (SERT) function have been implicated in autism. SERT function is influenced by the number of transporter molecules present at the cell surface, which is regulated by various cellular mechanisms including interactions with other proteins. Thus, we searched for novel SERT-binding proteins and investigated whether the expression of one such protein was affected in subjects with autism. Methods Novel SERT-binding proteins were examined by a pull-down system. Alterations of SERT function and membrane expression upon knockdown of the novel SERT-binding protein were studied in HEK293-hSERT cells. Endogenous interaction of SERT with the protein was evaluated in mouse brains. Alterations in the mRNA expression of SERT (SLC6A4) and the SERT-binding protein in the post-mortem brains and the lymphocytes of autism patients were compared to nonclinical controls. Results N-ethylmaleimide-sensitive factor (NSF) was identified as a novel SERT-binding protein. NSF was co-localized with SERT at the plasma membrane, and NSF knockdown resulted in decreased SERT expression at the cell membranes and decreased SERT uptake function. NSF was endogenously co-localized with SERT and interacted with SERT. While SLC6A4 expression was not significantly changed, NSF expression tended to be reduced in post-mortem brains, and was significantly reduced in lymphocytes of autistic subjects, which correlated with the severity of the clinical symptoms. Conclusions These data clearly show that NSF interacts with SERT under physiological conditions and is required for SERT membrane trafficking and uptake function. A possible role for NSF in the pathophysiology of autism through modulation of SERT trafficking, is suggested. PMID:24834316

Determinants in the β and δ subunit cytoplasmic loop regulate Golgi trafficking and surface expression of the muscle acetylcholine receptor.

PubMed

Rudell, Jolene Chang; Borges, Lucia S; Rudell, John B; Beck, Kenneth A; Ferns, Michael J

2014-01-03

The molecular determinants that govern nicotinic acetylcholine receptor (AChR) assembly and trafficking are poorly defined, and those identified operate largely during initial receptor biogenesis in the endoplasmic reticulum. To identify determinants that regulate later trafficking steps, we performed an unbiased screen using chimeric proteins consisting of CD4 fused to the muscle AChR subunit cytoplasmic loops. In C2 mouse muscle cells, we found that CD4-β and δ subunit loops were expressed at very low levels on the cell surface, whereas the other subunit loops were robustly expressed on the plasma membrane. The low surface expression of CD4-β and δ loops was due to their pronounced retention in the Golgi apparatus and also to their rapid internalization from the plasma membrane. Both retention and recovery were mediated by the proximal 25-28 amino acids in each loop and were dependent on an ordered sequence of charged and hydrophobic residues. Indeed, βK353L and δK351L mutations increased surface trafficking of the CD4-subunit loops by >6-fold and also decreased their internalization from the plasma membrane. Similarly, combined βK353L and δK351L mutations increased the surface levels of assembled AChR expressed in HEK cells to 138% of wild-type levels. This was due to increased trafficking to the plasma membrane and not decreased AChR turnover. These findings identify novel Golgi retention signals in the β and δ subunit loops that regulate surface trafficking of assembled AChR and may help prevent surface expression of unassembled subunits. Together, these results define molecular determinants that govern a Golgi-based regulatory step in nicotinic AChR trafficking.

Divalent metal transporter 1 (DMT1) in the brain: implications for a role in iron transport at the blood-brain barrier, and neuronal and glial pathology.

PubMed

Skjørringe, Tina; Burkhart, Annette; Johnsen, Kasper Bendix; Moos, Torben

2015-01-01

Iron is required in a variety of essential processes in the body. In this review, we focus on iron transport in the brain and the role of the divalent metal transporter 1 (DMT1) vital for iron uptake in most cells. DMT1 locates to cellular membranes and endosomal membranes, where it is a key player in non-transferrin bound iron uptake and transferrin-bound iron uptake, respectively. Four isoforms of DMT1 exist, and their respective characteristics involve a complex cell-specific regulatory machinery all controlling iron transport across these membranes. This complexity reflects the fine balance required in iron homeostasis, as this metal is indispensable in many cell functions but highly toxic when appearing in excess. DMT1 expression in the brain is prominent in neurons. Of serious dispute is the expression of DMT1 in non-neuronal cells. Recent studies imply that DMT1 does exist in endosomes of brain capillary endothelial cells denoting the blood-brain barrier. This supports existing evidence that iron uptake at the BBB occurs by means of transferrin-receptor mediated endocytosis followed by detachment of iron from transferrin inside the acidic compartment of the endosome and DMT1-mediated pumping iron into the cytosol. The subsequent iron transport across the abluminal membrane into the brain likely occurs by ferroportin. The virtual absent expression of transferrin receptors and DMT1 in glial cells, i.e., astrocytes, microglia and oligodendrocytes, suggest that the steady state uptake of iron in glia is much lower than in neurons and/or other mechanisms for iron uptake in these cell types prevail.

Divalent metal transporter 1 (DMT1) in the brain: implications for a role in iron transport at the blood-brain barrier, and neuronal and glial pathology

PubMed Central

Skjørringe, Tina; Burkhart, Annette; Johnsen, Kasper Bendix; Moos, Torben

2015-01-01

Iron is required in a variety of essential processes in the body. In this review, we focus on iron transport in the brain and the role of the divalent metal transporter 1 (DMT1) vital for iron uptake in most cells. DMT1 locates to cellular membranes and endosomal membranes, where it is a key player in non-transferrin bound iron uptake and transferrin-bound iron uptake, respectively. Four isoforms of DMT1 exist, and their respective characteristics involve a complex cell-specific regulatory machinery all controlling iron transport across these membranes. This complexity reflects the fine balance required in iron homeostasis, as this metal is indispensable in many cell functions but highly toxic when appearing in excess. DMT1 expression in the brain is prominent in neurons. Of serious dispute is the expression of DMT1 in non-neuronal cells. Recent studies imply that DMT1 does exist in endosomes of brain capillary endothelial cells denoting the blood-brain barrier. This supports existing evidence that iron uptake at the BBB occurs by means of transferrin-receptor mediated endocytosis followed by detachment of iron from transferrin inside the acidic compartment of the endosome and DMT1-mediated pumping iron into the cytosol. The subsequent iron transport across the abluminal membrane into the brain likely occurs by ferroportin. The virtual absent expression of transferrin receptors and DMT1 in glial cells, i.e., astrocytes, microglia and oligodendrocytes, suggest that the steady state uptake of iron in glia is much lower than in neurons and/or other mechanisms for iron uptake in these cell types prevail. PMID:26106291

Lipopolysaccharide inhibits colonic biotin uptake via interference with membrane expression of its transporter: a role for a casein kinase 2-mediated pathway.

PubMed

Lakhan, Ram; Said, Hamid M

2017-04-01

Biotin (vitamin B7), an essential micronutrient for normal cellular functions, is obtained from both dietary sources as well as gut microbiota. Absorption of biotin in both the small and large intestine is via a carrier-mediated process that involves the sodium-dependent multivitamin transporter (SMVT). Although different physiological and molecular aspects of intestinal biotin uptake have been delineated, nothing is known about the effect of LPS on the process. We addressed this issue using in vitro (human colonic epithelial NCM460 cells) and in vivo (mice) models of LPS exposure. Treating NCM460 cells with LPS was found to lead to a significant inhibition in carrier-mediated biotin uptake. Similarly, administration of LPS to mice led to a significant inhibition in biotin uptake by native colonic tissue. Although no changes in total cellular SMVT protein and mRNA levels were observed, LPS caused a decrease in the fraction of SMVT expressed at the cell surface. A role for casein kinase 2 (CK2) (whose activity was also inhibited by LPS) in mediating the endotoxin effects on biotin uptake and on membrane expression of SMVT was suggested by findings that specific inhibitors of CK2, as well as mutating the putative CK2 phosphorylation site (Thr 78 Ala) in the SMVT protein, led to inhibition in biotin uptake and membrane expression of SMVT. This study shows for the first time that LPS inhibits colonic biotin uptake via decreasing membrane expression of its transporter and that these effects likely involve a CK2-mediated pathway.

Lipopolysaccharide inhibits colonic biotin uptake via interference with membrane expression of its transporter: a role for a casein kinase 2-mediated pathway

PubMed Central

Lakhan, Ram

2017-01-01

Biotin (vitamin B7), an essential micronutrient for normal cellular functions, is obtained from both dietary sources as well as gut microbiota. Absorption of biotin in both the small and large intestine is via a carrier-mediated process that involves the sodium-dependent multivitamin transporter (SMVT). Although different physiological and molecular aspects of intestinal biotin uptake have been delineated, nothing is known about the effect of LPS on the process. We addressed this issue using in vitro (human colonic epithelial NCM460 cells) and in vivo (mice) models of LPS exposure. Treating NCM460 cells with LPS was found to lead to a significant inhibition in carrier-mediated biotin uptake. Similarly, administration of LPS to mice led to a significant inhibition in biotin uptake by native colonic tissue. Although no changes in total cellular SMVT protein and mRNA levels were observed, LPS caused a decrease in the fraction of SMVT expressed at the cell surface. A role for casein kinase 2 (CK2) (whose activity was also inhibited by LPS) in mediating the endotoxin effects on biotin uptake and on membrane expression of SMVT was suggested by findings that specific inhibitors of CK2, as well as mutating the putative CK2 phosphorylation site (Thr78Ala) in the SMVT protein, led to inhibition in biotin uptake and membrane expression of SMVT. This study shows for the first time that LPS inhibits colonic biotin uptake via decreasing membrane expression of its transporter and that these effects likely involve a CK2-mediated pathway. PMID:28052864

Correlation of N-myc downstream-regulated gene 1 subcellular localization and lymph node metastases of colorectal neoplasms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Yan; Lv, Liyang; Du, Juan

2013-09-20

Highlights: •We clarified NDRG1 subcellular location in colorectal cancer. •We found the changes of NDRG1 distribution during colorectal cancer progression. •We clarified the correlation between NDRG1 distribution and lymph node metastasis. •It is possible that NDRG1 subcellular localization may determine its function. •Maybe NDRG1 is valuable early diagnostic markers for metastasis. -- Abstract: In colorectal neoplasms, N-myc downstream-regulated gene 1 (NDRG1) is a primarily cytoplasmic protein, but it is also expressed on the cell membrane and in the nucleus. NDRG1 is involved in various stages of tumor development in colorectal cancer, and it is possible that the different subcellular localizationsmore » may determine the function of NDRG1 protein. Here, we attempt to clarify the characteristics of NDRG1 protein subcellular localization during the progression of colorectal cancer. We examined NDRG1 expression in 49 colorectal cancer patients in cancerous, non-cancerous, and corresponding lymph node tissues. Cytoplasmic and membrane NDRG1 expression was higher in the lymph nodes with metastases than in those without metastases (P < 0.01). Nuclear NDRG1 expression in colorectal neoplasms was significantly higher than in the normal colorectal mucosa, and yet the normal colorectal mucosa showed no nuclear expression. Furthermore, our results showed higher cytoplasmic NDRG1 expression was better for differentiation, and higher membrane NDRG1 expression resulted in a greater possibility of lymph node metastasis. These data indicate that a certain relationship between the cytoplasmic and membrane expression of NDRG1 in lymph nodes exists with lymph node metastasis. NDRG1 expression may translocate from the membrane of the colorectal cancer cells to the nucleus, where it is involved in lymph node metastasis. Combination analysis of NDRG1 subcellular expression and clinical variables will help predict the incidence of lymph node metastasis.« less

Vitamin E-coated dialyzer membranes downregulate expression of monocyte adhesion and co-stimulatory molecules.

PubMed

Betjes, Michiel G H; Hoekstra, Franciska M E; Klepper, M; Postma, Saskia M; Vaessen, Leonard M B

2004-01-01

In patients on chronic hemodialysis leukocyte activation has been related to the impaired function of the immune system. In this study we investigated if the vitamin E-coated dialyzer membrane could reduce monocyte activation thereby improving cellular immunity. This hypothesis was tested in a prospective crossover trial in which 14 stable hemodialysis patients were switched from the baseline hemophane dialyzer to a vitamin E-coated and thereafter a polysulphone dialyzer membrane or vice versa. Monocyte MHC class I, CD54 and ICAM-1 expression was significantly downregulated when a vitamin E-coated or polysulphone dialyzer was used. The use of a vitamin E membrane specifically decreased monocyte CD40 and CD86 expression. Lectin induced T cell proliferation increased with the use of the vitamin E-coated membrane as compared to polysulphone and hemophane dialyzers. Vitamin E-coated dialyzers induced a less-activated phenotype of monocytes and may improve cellular immunity.

Secreted Oral Epithelial Cell Membrane Vesicles Induce Epstein-Barr Virus Reactivation in Latently Infected B Cells

PubMed Central

Lin, Zhen; Swan, Kenneth; Zhang, Xin; Cao, Subing; Brett, Zoe; Drury, Stacy; Fewell, Claire; Puetter, Adriane; Wang, Xia; Ferris, MaryBeth; Sullivan, Deborah E.; Li, Li

2016-01-01

ABSTRACT In the oral epithelium, peripheral stores of Epstein-Barr virus (EBV) are transmitted from infiltrating B cells to epithelial cells. Once the virus is transmitted to epithelial cells, the highly permissive nature of this cell type for lytic replication allows virus amplification and exchange to other hosts. Since the initial transfer of EBV from B cells to epithelial cells requires transitioning of the B-cell to a state that induces virus reactivation, we hypothesized that there might be epithelium-specific signals that allow the infiltrating B cells to sense the appropriate environment to initiate reactivation and begin this exchange process. We previously found that the epithelium-specific miR-200 family of microRNAs promotes EBV lytic replication. Here we show that there are high levels of miR-200 family members in oral and tonsillar epithelia and in saliva. Analysis of cultured oral epithelial cells (OKF6) showed that they actively secrete membrane vesicles (exosomes) that are enriched with miR-200 family members. Coculturing of EBV-positive B cells with OKF6 cells induced viral reactivation. Further, treatment of EBV-positive B cells with OKF6 cell-derived membrane vesicles promoted reactivation. Using a cell system that does not naturally express miR-200 family members, we found that enforced expression of a miR-200 family member produced membrane vesicles that were able to induce the lytic cascade in EBV-positive B cells. We propose that membrane vesicles secreted by oral and tonsillar epithelial cells may serve as a tissue-specific environmental cue that initiates reactivation in B cells, promoting the transfer of virus from peripheral B-cell stores to the oral epithelium to facilitate virus amplification and exchange to other hosts. IMPORTANCE Epstein-Barr virus (EBV) is an important human pathogen that is causally associated with several lymphomas and carcinomas. The switch from latency to the lytic cycle is critical for successful host infection and for EBV pathogenesis. Although the EBV lytic cycle can be triggered by certain agents in vitro, the mechanisms that signal reactivation in vivo are poorly understood. We previously reported that endogenously expressed miR-200 family members likely play a role in facilitating the lytic tendencies of EBV in epithelial cells. Here we show that membrane vesicles secreted from oral epithelial cells contain miR-200 family members and that they can be transmitted to proximal EBV-positive B cells, where they trigger reactivation. We propose that this intercellular communication pathway may serve as a sensor mechanism for infiltrating B cells to recognize an appropriate environment to initiate reactivation, thereby allowing the exchange of virus to the oral epithelium. PMID:26764001

In vitro culture and characterization of human lung cancer circulating tumor cells isolated by size exclusion from an orthotopic nude-mouse model expressing fluorescent protein.

PubMed

Kolostova, Katarina; Zhang, Yong; Hoffman, Robert M; Bobek, Vladimir

2014-09-01

In the present study, we demonstrate an animal model and recently introduced size-based exclusion method for circulating tumor cells (CTCs) isolation. The methodology enables subsequent in vitro CTC-culture and characterization. Human lung cancer cell line H460, expressing red fluorescent protein (H460-RFP), was orthotopically implanted in nude mice. CTCs were isolated by a size-based filtration method and successfully cultured in vitro on the separating membrane (MetaCell®), analyzed by means of time-lapse imaging. The cultured CTCs were heterogeneous in size and morphology even though they originated from a single tumor. The outer CTC-membranes were blebbing in general. Abnormal mitosis resulting in three daughter cells was frequently observed. The expression of RFP ensured that the CTCs originated from lung tumor. These readily isolatable, identifiable and cultivable CTCs can be used to characterize individual patient cancers and for screening of more effective treatment.

The herpes simplex virus receptor nectin-1 is down-regulated after trans-interaction with glycoprotein D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stiles, Katie M.; Center for Oral Health Research, School of Dental Medicine University of Pennsylvania, Philadelphia, PA 19104; Milne, Richard S.B.

2008-03-30

During herpes simplex virus (HSV) entry, membrane fusion occurs either on the cell surface or after virus endocytosis. In both cases, binding of glycoprotein D (gD) to a receptor such as nectin-1 or HVEM is required. In this study, we co-cultured cells expressing gD with nectin-1 expressing cells to investigate the effects of gD on nectin-1 at cell contacts. After overnight co-cultures with gD expressing cells, there was a down-regulation of nectin-1 in B78H1-C10, SY5Y, A431 and HeLa cells, which HSV enters by endocytosis. In contrast, on Vero cells, which HSV enters at the plasma membrane, nectin-1 was not down-regulated.more » Further analysis of B78H1-derived cells showed that nectin-1 down-regulation corresponds to the ability of gD to bind nectin-1 and is achieved by internalization and low-pH-dependent degradation of nectin-1. Moreover, gD is necessary for virion internalization in B78H1 cells expressing nectin-1. These data suggest that the determinants of gD-mediated internalization of nectin-1 may direct HSV to an endocytic pathway during entry.« less

Expression in Escherichia coli of the Saccharomyces cerevisiae CCT gene encoding cholinephosphate cytidylyltransferase.

PubMed Central

Tsukagoshi, Y; Nikawa, J; Hosaka, K; Yamashita, S

1991-01-01

The coding region of the CCT gene from the yeast Saccharomyces cerevisiae was cloned into the pUC18 expression vector. The plasmid directed the synthesis of an active cholinephosphate cytidylyltransferase in Escherichia coli, confirming that CCT is the structural gene for this enzyme. The enzyme produced in E. coli efficiently utilized cholinephosphate and N,N-dimethylethanolaminephosphate, but N-methylethanolamine-phosphate and ethanolaminephosphate were poor substrates. Consistently, disruption of the CCT locus in the wild-type yeast cells resulted in a drastic decrease in activities with respect to the former two substrates. When activity was expressed in E. coli, over 90% was recovered in the cytosol, whereas most of the activity of yeast cells was associated with membranes, suggesting that yeast cells possess a mechanism that promotes membrane association of cytidylyltransferase. Images PMID:1848222

Dual patch voltage clamp study of low membrane resistance astrocytes in situ.

PubMed

Ma, Baofeng; Xu, Guangjin; Wang, Wei; Enyeart, John J; Zhou, Min

2014-03-17

Whole-cell patch clamp recording has been successfully used in identifying the voltage-dependent gating and conductance properties of ion channels in a variety of cells. However, this powerful technique is of limited value in studying low membrane resistance cells, such as astrocytes in situ, because of the inability to control or accurately measure the real amplitude of command voltages. To facilitate the study of ionic conductances of astrocytes, we have developed a dual patch recording method which permits membrane current and membrane potential to be simultaneously recorded from astrocytes in spite of their extraordinarily low membrane resistance. The utility of this technique is demonstrated by measuring the voltage-dependent activation of the inwardly rectifying K+ current abundantly expressed in astrocytes and multiple ionic events associated with astrocytic GABAA receptor activation. This protocol can be performed routinely in the study of astrocytes. This method will be valuable for identifying and characterizing the individual ion channels that orchestrate the electrical activity of low membrane resistance cells.

CD39/NTPDase-1 expression and activity in human umbilical vein endothelial cells are differentially regulated by leaf extracts from Rubus caesius and Rubus idaeus.

PubMed

Dudzinska, Dominika; Luzak, Boguslawa; Boncler, Magdalena; Rywaniak, Joanna; Sosnowska, Dorota; Podsedek, Anna; Watala, Cezary

2014-09-01

Many experimental studies have demonstrated the favorable biological activities of plants belonging to the genus Rubus, but little is known of the role of Rubus leaf extracts in the modulation of the surface membrane expression and activity of endothelial apyrase. The aim of this study was to assess the influence of 1-15 μg/ml Rubus extracts on CD39 expression and enzymatic activity, and on the activation (ICAM-1 expression) and viability of human umbilical vein endothelial cells (HUVEC). The polyphenolic contents and antioxidative capacities of extracts from dewberry (R. caesius L.) and raspberry (R. idaeus L.) leaves were also investigated. The techniques applied were flow cytometry (endothelial surface membrane expression of ICAM-1 and CD39), malachite green assay (CD39 activity), HPLC-DAD (quantitative analysis of polyphenolic extract), ABTS, DPPH and FRAP spectrometric assays (antioxidant capacity), and the MTT test (cell viability). Significantly increased CD39 expressions and significantly decreased ATPDase activities were found in the cells treated with 15 μg/ml of either extract compared to the results for the controls. Neither of the extracts affected cell proliferation, but both significantly augmented endothelial cell ICAM-1 expression. The overall antioxidant capacities of the examined extracts remained relatively high and corresponded well to the determined total polyphenol contents. Overall, the results indicate that under in vitro conditions dewberry and raspberry leaf extracts have unfavorable impact on endothelial cells.

Expression, Biochemistry, and Stabilization with Camel Antibodies of Membrane Proteins: Case Study of the Mouse 5-HT3 Receptor.

PubMed

Hassaïne, Ghérici; Deluz, Cédric; Grasso, Luigino; Wyss, Romain; Hovius, Ruud; Stahlberg, Henning; Tomizaki, Takashi; Desmyter, Aline; Moreau, Christophe; Peclinovska, Lucie; Minniberger, Sonja; Mebarki, Lamia; Li, Xiao-Dan; Vogel, Horst; Nury, Hugues

2017-01-01

There is growing interest in the use of mammalian protein expression systems, and in the use of antibody-derived chaperones, for structural studies. Here, we describe protocols ranging from the production of recombinant membrane proteins in stable inducible cell lines to biophysical characterization of purified membrane proteins in complex with llama antibody domains. These protocols were used to solve the structure of the mouse 5-HT3 serotonin receptor but are of broad applicability for crystallization or cryo-electron microscopy projects.

Membrane-bound heat shock proteins facilitate the uptake of dying cells and cross-presentation of cellular antigen.

PubMed

Zhu, Haiyan; Fang, Xiaoyun; Zhang, Dongmei; Wu, Weicheng; Shao, Miaomiao; Wang, Lan; Gu, Jianxin

2016-01-01

Heat shock proteins (HSPs) were originally identified as stress-responsive proteins and serve as molecular chaperones in different intracellular compartments. Translocation of HSPs to the cell surface and release of HSPs into the extracellular space have been observed during the apoptotic process and in response to a variety of cellular stress. Here, we report that UV irradiation and cisplatin treatment rapidly induce the expression of membrane-bound Hsp60, Hsp70, and Hsp90 upstream the phosphatidylserine exposure. Membrane-bound Hsp60, Hsp70 and Hsp90 could promote the release of IL-6 and IL-1β as well as DC maturation by the evaluation of CD80 and CD86 expression. On the other hand, Hsp60, Hsp70 and Hsp90 on cells could facilitate the uptake of dying cells by bone marrow-derived dendritic cells. Lectin-like oxidized LDL receptor-1 (LOX-1), as a common receptor for Hsp60, Hsp70, and Hsp90, is response for their recognition and mediates the uptake of dying cells. Furthermore, membrane-bound Hsp60, Hsp70 and Hsp90 could promote the cross-presentation of OVA antigen from E.G7 cells and inhibition of the uptake of dying cells by LOX-1 decreases the cross-presentation of cellular antigen. Therefore, the rapid exposure of HSPs on dying cells at the early stage allows for the recognition by and confers an activation signal to the immune system.

PIG7 promotes leukemia cell chemosensitivity via lysosomal membrane permeabilization

PubMed Central

Niu, Ting; Wu, Yu; Li, Jianjun; Wang, Fangfang; Zheng, Yuhuan; Liu, Ting

2016-01-01

PIG7 localizes to lysosomal membrane in leukemia cells. Our previous work has shown that transduction of pig7 into a series of leukemia cell lines did not result in either apoptosis or differentiation of most tested cell lines. Interestingly, it did significantly sensitize these cell lines to chemotherapeutic drugs. Here, we further investigated the mechanism underlying pig7-induced improved sensitivity of acute leukemia cells to chemotherapy. Our results demonstrated that the sensitization effect driven by exogenous pig7 was more effective in drug-resistant leukemia cell lines which had lower endogenous pig7 expression. Overexpression of pig7 did not directly activate the caspase apoptotic pathway, but decreased the lysosomal stability. The expression of pig7 resulted in lysosomal membrane permeabilization (LMP) and lysosomal protease (e.g. cathepsin B, D, L) release. Moreover, we also observed increased reactive oxygen species (ROS) and decreased mitochondrial membrane potential (ΔΨm) induced by pig7. Some autophagy markers such as LC3I/II, ATG5 and Beclin-1, and necroptosis maker MLKL were also stimulated. However, intrinsic antagonism such as serine/cysteine protease inhibitors Spi2A and Cystatin C prevented downstream effectors from triggering leukemia cells, which were only on the “verge of apoptosis”. When combined with chemotherapy, LMP increased and more proteases were released. Once this process was beyond the limit of intrinsic antagonism, it induced programmed cell death cooperatively via caspase-independent and caspase-dependent pathways. PMID:26716897

An Acidic Cluster in the Cytosolic Domain of Human Cytomegalovirus Glycoprotein B Is a Signal for Endocytosis from the Plasma Membrane

PubMed Central

Tugizov, Sharof; Maidji, Ekaterina; Xiao, Jianqiao; Pereira, Lenore

1999-01-01

We previously reported that human cytomegalovirus (CMV) glycoprotein B (gB) is transported to apical membranes in CMV-infected polarized retinal pigment epithelial (ARPE-19) cells and in Madin-Darby canine kidney (MDCK) epithelial cells constitutively expressing gB. The cytosolic domain of gB contains a cluster of acidic amino acids, a motif that plays a pivotal role in vectorial trafficking in polarized epithelial cells and may also function as a signal for entry into the endocytic pathway. Here we compared gB internalization and recycling to the plasma membrane in CMV-infected human fibroblasts (HF) and ARPE-19 cells by using antibody-internalization experiments. Immunofluorescence and quantitative assays showed that gB was internalized from the cell surface into clathrin-coated transport vesicles and then recycled to the plasma membrane. gB colocalized with clathrin-coated vesicles containing the transferrin receptor in the early endocytic/recycling pathway, indicating that gB traffics in this pathway. The specific role of the acidic cluster in regulating the sorting of gB-containing vesicles in the early endocytic/recycling pathway was examined in MDCK cells expressing mutated gB derivatives. Immunofluorescence assays showed that derivatives lacking the acidic cluster were impaired in internalization and failed to recycle. These findings, together with our earlier observation that the acidic cluster is a key determinant for targeting gB molecules to apical membranes in epithelial cells, establish that this signal is recognized by cellular proteins that participate in polarized sorting and transport in the early endocytic/recycling pathway. PMID:10482621

Multi-layer membrane model for mass transport in a direct ethanol fuel cell using an alkaline anion exchange membrane

NASA Astrophysics Data System (ADS)

Bahrami, Hafez; Faghri, Amir

2012-11-01

A one-dimensional, isothermal, single-phase model is presented to investigate the mass transport in a direct ethanol fuel cell incorporating an alkaline anion exchange membrane. The electrochemistry is analytically solved and the closed-form solution is provided for two limiting cases assuming Tafel expressions for both oxygen reduction and ethanol oxidation. A multi-layer membrane model is proposed to properly account for the diffusive and electroosmotic transport of ethanol through the membrane. The fundamental differences in fuel crossover for positive and negative electroosmotic drag coefficients are discussed. It is found that ethanol crossover is significantly reduced upon using an alkaline anion exchange membrane instead of a proton exchange membrane, especially at current densities higher than 500 A m

A novel CXCL10-based GPI-anchored fusion protein as adjuvant in NK-based tumor therapy.

PubMed

Muenchmeier, Niklas; Boecker, Sophia; Bankel, Lorenz; Hinz, Laura; Rieth, Nicole; Lapa, Constantin; Mendler, Anna N; Noessner, Elfriede; Mocikat, Ralph; Nelson, Peter J

2013-01-01

Cellular therapy is a promising therapeutic strategy for malignant diseases. The efficacy of this therapy can be limited by poor infiltration of the tumor by immune effector cells. In particular, NK cell infiltration is often reduced relative to T cells. A novel class of fusion proteins was designed to enhance the recruitment of specific leukocyte subsets based on their expression of a given chemokine receptor. The proteins are composed of an N-terminal chemokine head, the mucin domain taken from the membrane-anchored chemokine CX3CL1, and a C-terminal glycosylphosphatidylinositol (GPI) membrane anchor replacing the normal transmembrane domain allowing integration of the proteins into cell membranes when injected into a solid tumor. The mucin domain in conjunction with the chemokine head acts to specifically recruit leukocytes expressing the corresponding chemokine receptor. A fusion protein comprising a CXCL10 chemokine head (CXCL10-mucin-GPI) was used for proof of concept for this approach and expressed constitutively in Chinese Hamster Ovary cells. FPLC was used to purify proteins. The recombinant proteins efficiently integrated into cell membranes in a process dependent upon the GPI anchor and were able to activate the CXCR3 receptor on lymphocytes. Endothelial cells incubated with CXCL10-mucin-GPI efficiently recruited NK cells in vitro under conditions of physiologic flow, which was shown to be dependent on the presence of the mucin domain. Experiments conducted in vivo using established tumors in mice suggested a positive effect of CXCL10-mucin-GPI on the recruitment of NK cells. The results suggest enhanced recruitment of NK cells by CXCL10-mucin-GPI. This class of fusion proteins represents a novel adjuvant in cellular immunotherapy. The underlying concept of a chemokine head fused to the mucin domain and a GPI anchor signal sequence may be expanded into a broader family of reagents that will allow targeted recruitment of cells in various settings.

Expression and testing in plants of ArcLight, a genetically-encoded voltage indicator used in neuroscience research.

PubMed

Matzke, Antonius J M; Matzke, Marjori

2015-10-12

It is increasingly appreciated that electrical controls acting at the cellular and supra-cellular levels influence development and initiate rapid responses to environmental cues. An emerging method for non-invasive optical imaging of electrical activity at cell membranes uses genetically-encoded voltage indicators (GEVIs). Developed by neuroscientists to chart neuronal circuits in animals, GEVIs comprise a fluorescent protein that is fused to a voltage-sensing domain. One well-known GEVI, ArcLight, undergoes strong shifts in fluorescence intensity in response to voltage changes in mammalian cells. ArcLight consists of super-ecliptic (SE) pHluorin (pH-sensitive fluorescent protein) with an A227D substitution, which confers voltage sensitivity in neurons, fused to the voltage-sensing domain of the voltage-sensing phosphatase of C iona i ntestinalis (Ci-VSD). In an ongoing effort to adapt tools of optical electrophysiology for plants, we describe here the expression and testing of ArcLight and various derivatives in different membranes of root cells in Arabidopsis thaliana. Transgenic constructs were designed to express ArcLight and various derivatives targeted to the plasma membrane and nuclear membranes of Arabidopsis root cells. In transgenic seedlings, changes in fluorescence intensity of these reporter proteins following extracellular ATP (eATP) application were monitored using a fluorescence microscope equipped with a high speed camera. Coordinate reductions in fluorescence intensity of ArcLight and Ci-VSD-containing derivatives were observed at both the plasma membrane and nuclear membranes following eATP treatments. However, similar responses were observed for derivatives lacking the Ci-VSD. The dispensability of the Ci-VSD suggests that in plants, where H(+) ions contribute substantially to electrical activities, the voltage-sensing ability of ArcLight is subordinate to the pH sensitivity of its SEpHluorin base. The transient reduction of ArcLight fluorescence triggered by eATP most likely reflects changes in pH and not membrane voltage. The pH sensitivity of ArcLight precludes its use as a direct sensor of membrane voltage in plants. Nevertheless, ArcLight and derivatives situated in the plasma membrane and nuclear membranes may offer robust, fluorescence intensity-based pH indicators for monitoring concurrent changes in pH at these discrete membrane systems. Such tools will assist analyses of pH as a signal and/or messenger at the cell surface and the nuclear periphery in living plants.

Comparison of Gene Expression in Human Embryonic Stem Cells, hESC-Derived Mesenchymal Stem Cells and Human Mesenchymal Stem Cells.

PubMed

Barbet, Romain; Peiffer, Isabelle; Hatzfeld, Antoinette; Charbord, Pierre; Hatzfeld, Jacques A

2011-01-01

We present a strategy to identify developmental/differentiation and plasma membrane marker genes of the most primitive human Mesenchymal Stem Cells (hMSCs). Using sensitive and quantitative TaqMan Low Density Arrays (TLDA) methodology, we compared the expression of 381 genes in human Embryonic Stem Cells (hESCs), hESC-derived MSCs (hES-MSCs), and hMSCs. Analysis of differentiation genes indicated that hES-MSCs express the sarcomeric muscle lineage in addition to the classical mesenchymal lineages, suggesting they are more primitive than hMSCs. Transcript analysis of membrane antigens suggests that IL1R1(low), BMPR1B(low), FLT4(low), LRRC32(low), and CD34 may be good candidates for the detection and isolation of the most primitive hMSCs. The expression in hMSCs of cytokine genes, such as IL6, IL8, or FLT3LG, without expression of the corresponding receptor, suggests a role for these cytokines in the paracrine control of stem cell niches. Our database may be shared with other laboratories in order to explore the considerable clinical potential of hES-MSCs, which appear to represent an intermediate developmental stage between hESCs and hMSCs.

Regulation of the vasopressin V2 receptor by vasopressin in polarized renal collecting duct cells.

PubMed

Robben, J H; Knoers, N V A M; Deen, P M T

2004-12-01

Binding of arginine-vasopressin (AVP) to its V2 receptor (V2R) in the basolateral membrane of principal cells induces Aquaporin-2-mediated water reabsorption in the kidney. To study the regulation of the V2R by dDAVP in a proper model, a polarized renal cell line stably-expressing V2R-GFP was generated. Labeled AVP-binding studies revealed an equal basolateral vs. apical membrane distribution for V2R-GFP and endogenous V2R. In these cells, GFP-V2R was expressed in its mature form and localized for 75% in the basolateral membrane and for 25% to late endosomes/lysosomes. dDAVP caused a dose- and time-dependent internalization of V2R-GFP, which was completed within 1 h with 100 nM dDAVP, was prevented by coincubation with a V2R antagonist, and which reduced its half-life from 11.5 to 2.8 h. Semiquantification of the V2R-GFP colocalization with E-cadherin (basolateral membrane), early endosomal antigen-1 (EEA-1) and lysosome-associated membrane protein-2 (LAMP-2) in time revealed that most dDAVP-bound V2R was internalized via early endosomes to late endosomes/lysosomes, where it was degraded. The dDAVP-internalized V2R did not recycle to the basolateral membrane. In conclusion, we established the itinerary of the V2R in a polarized cell model that likely resembles the in vivo V2R localization and regulation by AVP to a great extent.

High yield cell-free production of integral membrane proteins without refolding or detergents.

PubMed

Wuu, Jessica J; Swartz, James R

2008-05-01

Integral membrane proteins act as critical cellular components and are important drug targets. However, difficulties in producing membrane proteins have hampered investigations of structure and function. In vivo production systems are often limited by cell toxicity, and previous in vitro approaches have required unnatural folding pathways using detergents or lipid solutions. To overcome these limitations, we present an improved cell-free expression system which produces high yields of integral membrane proteins without the use of detergents or refolding steps. Our cell-free reaction activates an Escherichia coli-derived cell extract for transcription and translation. Purified E. coli inner membrane vesicles supply membrane-bound components and the lipid environment required for insertion and folding. Using this system, we demonstrated successful synthesis of two complex integral membrane transporters, the tetracycline pump (TetA) and mannitol permease (MtlA), in yields of 570+/-50 microg/mL and 130+/-30 microg/mL of vesicle-associated protein, respectively. These yields are up to 400 times typical in vivo concentrations. Insertion and folding of these proteins are verified by sucrose flotation, protease digestion, and activity assays. Whereas TetA incorporates efficiently into vesicle membranes with over two-thirds of the synthesized protein being inserted, MtlA yields appear to be limited by insufficient concentrations of a membrane-associated chaperone.

NaCl-Induced Alterations in Both Cell Structure and Tissue-Specific Plasma Membrane H+ -ATPase Gene Expression.

PubMed Central

Niu, X.; Damsz, B.; Kononowicz, A. K.; Bressan, R. A.; Hasegawa, P. M.

1996-01-01

NaCl-induced plasma membrane H+-ATPase gene expression, which occurs in roots and fully expanded leaves of the halophyte Atriplex nummularia L. (X. Niu, M.L. Narasimhan, R.A. Salzman, R.A. Bressan, P.M. Hasegawa [1993] Plant Physiol 103: 713-718), has been differentially localized to specific tissues using in situ RNA hybridization techniques. Twenty-four-hour exposure of plants to 400 mM NaCl resulted in substantial accumulation of H+ pump message in the epidermis of the root tip and the endodermis of the root elongation/differentiation zone. In expanded leaves, NaCl induction of plasma membrane H+-ATPase message accumulation was localized to bundle-sheath cells. Ultrastructural analyses indicated that significant cytological adaptations in root cells included plasmolysis that is accompanied by plasma membrane invaginations, formation of Hechtian strands and vesiculation, and vacuolation. These results identify specific tissues that are involved in the regulation of Na+ and Cl- uptake into different organs of the halophyte A. nummularia and provide evidence of the intercellular and interorgan coordination that occurs in the mediation of NaCl adaptation. PMID:12226321

NaCl-Induced Alterations in Both Cell Structure and Tissue-Specific Plasma Membrane H+ -ATPase Gene Expression.

PubMed

Niu, X.; Damsz, B.; Kononowicz, A. K.; Bressan, R. A.; Hasegawa, P. M.

1996-07-01

NaCl-induced plasma membrane H+-ATPase gene expression, which occurs in roots and fully expanded leaves of the halophyte Atriplex nummularia L. (X. Niu, M.L. Narasimhan, R.A. Salzman, R.A. Bressan, P.M. Hasegawa [1993] Plant Physiol 103: 713-718), has been differentially localized to specific tissues using in situ RNA hybridization techniques. Twenty-four-hour exposure of plants to 400 mM NaCl resulted in substantial accumulation of H+ pump message in the epidermis of the root tip and the endodermis of the root elongation/differentiation zone. In expanded leaves, NaCl induction of plasma membrane H+-ATPase message accumulation was localized to bundle-sheath cells. Ultrastructural analyses indicated that significant cytological adaptations in root cells included plasmolysis that is accompanied by plasma membrane invaginations, formation of Hechtian strands and vesiculation, and vacuolation. These results identify specific tissues that are involved in the regulation of Na+ and Cl- uptake into different organs of the halophyte A. nummularia and provide evidence of the intercellular and interorgan coordination that occurs in the mediation of NaCl adaptation.

Membrane protease degradomics: proteomic identification and quantification of cell surface protease substrates.

PubMed

Butler, Georgina S; Dean, Richard A; Smith, Derek; Overall, Christopher M

2009-01-01

The modification of cell surface proteins by plasma membrane and soluble proteases is important for physiological and pathological processes. Methods to identify shed and soluble substrates are crucial to further define the substrate repertoire, termed the substrate degradome, of individual proteases. Identifying protease substrates is essential to elucidate protease function and involvement in different homeostatic and disease pathways. This characterisation is also crucial for drug target identification and validation, which would then allow the rational design of specific targeted inhibitors for therapeutic intervention. We describe two methods for identifying and quantifying shed cell surface protease targets in cultured cells utilising Isotope-Coded Affinity Tags (ICAT) and Isobaric Tags for Relative and Absolute Quantification (iTRAQ). As a model system to develop these techniques, we chose a cell-membrane expressed matrix metalloproteinase, MMP-14, but the concepts can be applied to proteases of other classes. By over-expression, or conversely inhibition, of a particular protease with careful selection of control conditions (e.g. vector or inactive protease) and differential labelling, shed proteins can be identified and quantified by mass spectrometry (MS), MS/MS fragmentation and database searching.

The polarized distribution of poly(A+)-mRNA-induced functional ion channels in the Xenopus oocyte plasma membrane is prevented by anticytoskeletal drugs.

PubMed

Peter, A B; Schittny, J C; Niggli, V; Reuter, H; Sigel, E

1991-08-01

Foreign mRNA was expressed in Xenopus laevis oocytes. Newly expressed ion currents localized in defined plasma membrane areas were measured using the two-electrode voltage clamp technique in combination with a specially designed chamber, that exposed only part of the surface on the oocytes to channel agonists or inhibitors. Newly expressed currents were found to be unequally distributed in the surface membrane of the oocyte. This asymmetry was most pronounced during the early phase of expression, when channels could almost exclusively be detected in the animal hemisphere of the oocyte. 4 d after injection of the mRNA, or later, channels could be found at a threefold higher density at the animal than at the vegetal pole area. The pattern of distribution was observed to be similar with various ion channels expressed from crude tissue mRNA and from cRNAs coding for rat GABAA receptor channel subunits. Electron microscopical analysis revealed very similar microvilli patterns at both oocyte pole areas. Thus, the asymmetric current distribution is not due to asymmetric surface structure. Upon incubation during the expression period in either colchicine or cytochalasin D, the current density was found to be equal in both pole areas. The inactive control substance beta-lumicolchicine had no effect on the asymmetry of distribution. Colchicine was without effect on the amplitude of the expressed whole cell current. Our measurements reveal a pathway for plasma membrane protein expression endogenous to the Xenopus oocyte, that may contribute to the formation and maintenance of polarity of this highly organized cell.

Dynamic membrane depolarization is an early regulator of ependymoglial cell response to spinal cord injury in axolotl

PubMed Central

Sabin, Keith; Santos-Ferreira, Tiago; Essig, Jaclyn; Rudasill, Sarah; Echeverri, Karen

2016-01-01

Salamanders, such as the Mexican axolotl, are some of the few vertebrates fortunate in their ability to regenerate diverse structures after injury. Unlike mammals they are able to regenerate a fully functional spinal cord after injury. However, the molecular circuitry required to initiate a pro-regenerative response after spinal cord injury is not well understood. To address this question we developed a spinal cord injury model in axolotls and used in vivo imaging of labeled ependymoglial cells to characterize the response of these cells to injury. Using in vivo imaging of ion sensitive dyes we identified that spinal cord injury induces a rapid and dynamic change in the resting membrane potential of ependymoglial cells. Prolonged depolarization of ependymoglial cells after injury inhibits ependymoglial cell proliferation and subsequent axon regeneration. Using transcriptional profiling we identified c-Fos as a key voltage sensitive early response gene that is expressed specifically in the ependymoglial cells after injury. This data establishes that dynamic changes in the membrane potential after injury are essential for regulating the specific spatiotemporal expression of c-Fos that is critical for promoting faithful spinal cord regeneration in axolotl. PMID:26477559

Immunological consequences of kidney cell death.

PubMed

Sarhan, Maysa; von Mässenhausen, Anne; Hugo, Christian; Oberbauer, Rainer; Linkermann, Andreas

2018-01-25

Death of renal cells is central to the pathophysiology of acute tubular necrosis, autoimmunity, necrotizing glomerulonephritis, cystic kidney disease, urosepsis, delayed graft function and transplant rejection. By means of regulated necrosis, immunogenic damage-associated molecular patterns (DAMPs) and highly reactive organelles such as lysosomes, peroxisomes and mitochondria are released from the dying cells, thereby causing an overwhelming immunologic response. The rupture of the plasma membrane exhibits the "point of no return" for the immunogenicity of regulated cell death, explaining why apoptosis, a highly organized cell death subroutine with long-lasting plasma membrane integrity, elicits hardly any immune response. Ferroptosis, an iron-dependent necrotic type cell death, results in the release of DAMPs and large amounts of lipid peroxides. In contrast, anti-inflammatory cytokines are actively released from cells that die by necroptosis, limiting the DAMP-induced immune response to a surrounding microenvironment, whereas at the same time, inflammasome-associated caspases drive maturation of intracellularly expressed interleukin-1β (IL-1β). In a distinct setting, additionally interleukin-18 (IL-18) is expressed during pyroptosis, initiated by gasdermin-mediated plasma membrane rupture. As all of these pathways are druggable, we provide an overview of regulated necrosis in kidney diseases with a focus on immunogenicity and potential therapeutic interventions.

Toxicity of algicidal extracts from Mangrovimonas yunxiaonensis strain LY01 on a HAB causing Alexandrium tamarense.

PubMed

Li, Yi; Zhu, Hong; Zhang, Huajun; Chen, Zhangran; Tian, Yun; Xu, Hong; Zheng, Tianling; Zheng, Wei

2014-08-15

Toxicity of algicidal extracts from Mangrovimonas yunxiaonensis strain LY01 on Alexandrium tamarense were measured through studying the algicidal procedure, nuclear damage and transcription of related genes. Medium components were optimized to improve algicidal activity, and characteristics of algicidal extracts were determined. Transmission electron microscope analysis revealed that the cell structure was broken. Cell membrane integrity destruction and nuclear structure degradation were monitored using confocal laser scanning microscope, and the rbcS, hsp and proliferating cell nuclear antigen (PCNA) gene expressions were studied. Results showed that 1.0% tryptone, 0.4% glucose and 0.8% MgCl2 were the optimal nutrient sources. The algicidal extracts were heat and pH stable, non-protein and less than 1kD. Cell membrane and nuclear structure integrity were lost, and the transcription of the rbcS and PCNA genes were significantly inhibited and there was up-regulation of hsp gene expression during the exposure procedure. The algicidal extracts destroyed the cell membrane and nuclear structure integrity, inhibited related gene expression and, eventually, lead to the inhibition of algal growth. All the results may elaborate firstly the cell death process and nuclear damage in A. tamarense which was induced by algicidal extracts, and the algicidal extracts could be potentially used as bacterial control of HABs in future. Copyright © 2014 Elsevier B.V. All rights reserved.

Paracrine Activity from Adipose-Derived Stem Cells on In Vitro Wound Healing in Human Tympanic Membrane Keratinocytes.

PubMed

Ong, Huan Ting; Redmond, Sharon L; Marano, Robert J; Atlas, Marcus D; von Unge, Magnus; Aabel, Peder; Dilley, Rodney J

2017-03-15

Stem cell therapies for tympanic membrane repair have shown initial experimental success using mesenchymal stem cells in rat models to promote healing; however, the mechanisms providing this benefit are not known. We investigated in vitro the paracrine effects of human adipose-derived stem cells (ADSCs) on wound healing mechanisms for human tympanic membrane-derived keratinocytes (hTM) and immortalized human keratinocytes (HaCaT). ADSC conditioned media (CM ADSC ) were assessed for paracrine activity on keratinocyte proliferation and migration, with hypoxic conditions for ADSC culture used to generate contrasting effects on cytokine gene expression. Keratinocytes cultured in CM ADSC showed a significant increase in cell number compared to serum-free cultures and further significant increases in hypoxic CM ADSC . Assessment of ADSC gene expression on a cytokine array showed a range of wound healing cytokines expressed and under stringent hypoxic and serum-free conditions was upregulated (VEGF A, MMP9, Tissue Factor, PAI-1) or downregulated (CXCL5, CCL7, TNF-α). Several of these may contribute to the activity of conditioned media on the keratinocytes with potential applications in TM perforation repair. VEGFA protein was confirmed by immunoassay to be increased in conditioned media. Together with gene regulation associated with hypoxia in ADSCs, this study has provided several strong leads for a stem cell-derived approach to TM wound healing.

The effect of α2-δ and other accessory subunits on expression and properties of the calcium channel α1G

PubMed Central

Dolphin, A C; Wyatt, C N; Richards, J; Beattie, R E; Craig, P; Lee, J-H; Cribbs, L L; Volsen, S G; Perez-Reyes, E

1999-01-01

The effect has been examined of the accessory α2-δ and β subunits on the properties of α1G currents expressed in monkey COS-7 cells and Xenopus oocytes. In immunocytochemical experiments, the co-expression of α2-δ increased plasma membrane localization of expressed α1G and conversely, the heterologous expression of α1G increased immunostaining for endogenous α2-δ, suggesting an interaction between the two subunits. Heterologous expression of α2-δ together with α1G in COS-7 cells increased the amplitude of expressed α1G currents by about 2-fold. This finding was confirmed in the Xenopus oocyte expression system. The truncated δ construct did not increase α1G current amplitude, or increase its plasma membrane expression. This indicates that it is the exofacial α2 domain that is involved in the enhancement by α2-δ. β1b also produced an increase of functional expression of α1G, either in the absence or the presence of heterologously expressed α2-δ, whereas the other β subunits had much smaller effects. None of the accessory subunits had any marked influence on the voltage dependence or kinetics of the expressed α1G currents. These results therefore suggest that α2-δ and β1b interact with α1G to increase trafficking of, or stabilize, functional α1G channels expressed at the plasma membrane. PMID:10432337

DNA probe for monitoring dynamic and transient molecular encounters on live cell membranes

PubMed Central

You, Mingxu; Lyu, Yifan; Han, Da; Qiu, Liping; Liu, Qiaoling; Chen, Tao; Wu, Cuichen Sam; Peng, Lu; Zhang, Liqin; Bao, Gang; Tan, Weihong

2017-01-01

Cells interact with the extracellular environment through molecules expressed on the membrane. Disruption of these membrane-bound interactions (or encounters) can result in disease progression. Advances in super-resolution microscopy have allowed membrane encounters to be examined, however, these methods cannot image entire membranes and cannot provide information on the dynamic interactions between membrane-bound molecules. Here, we show a novel DNA probe that can transduce transient membrane encounter events into readable cumulative fluorescence signals. The probe, which translocates from one anchor site to another, such as motor proteins, is realized through a toehold-mediated DNA strand displacement reaction. Using this probe, we successfully monitored rapid encounter events of membrane lipid domains using flow cytometry and fluorescence microscopy. Our results show a preference for encounters within different lipid domains. PMID:28319616

Molecular cloning of a murine homologue of membrane cofactor protein (CD46): preferential expression in testicular germ cells.

PubMed Central

Tsujimura, A; Shida, K; Kitamura, M; Nomura, M; Takeda, J; Tanaka, H; Matsumoto, M; Matsumiya, K; Okuyama, A; Nishimune, Y; Okabe, M; Seya, T

1998-01-01

Human membrane cofactor protein (MCP, CD46) has been suggested, although no convincing evidence has been proposed, to be a fertilization-associated protein, in addition to its primary functions as a complement regulator and a measles virus receptor. We have cloned a cDNA encoding the murine homologue of MCP. This cDNA showed 45% identity in deduced protein sequence and 62% identity in nucleotide sequence with human MCP. Its ectodomains were four short consensus repeats and a serine/threonine-rich domain, and it appeared to be a type 1 membrane protein with a 23-amino acid transmembrane domain and a short cytoplasmic tail. The protein expressed on Chinese hamster ovary cell transfectants was 47 kDa on SDS/PAGE immunoblotting, approximately 6 kDa larger than the murine testis MCP. It served as a cofactor for factor I-mediated inactivation of the complement protein C3b in a homologous system and, to a lesser extent, in a human system. Strikingly, the major message of murine MCP was 1.5 kb and was expressed predominantly in the testis. It was not detected in mice defective in spermatogenesis or with immature germ cells (until 23 days old). Thus, murine MCP may be a sperm-dominant protein the message of which is expressed selectively in spermatids during germ-cell differentiation. PMID:9461505

Physical and functional interactions between a glioma cation channel and integrin-β1 require α-actinin

PubMed Central

Rooj, Arun K.; Liu, Zhiyong; McNicholas, Carmel M.

2015-01-01

Major plasma membrane components of the tumor cell, ion channels, and integrins play crucial roles in metastasis. Glioma cells express an amiloride-sensitive nonselective cation channel composed of acid-sensing ion channel (ASIC)-1 and epithelial Na+ channel (ENaC) α- and γ-subunits. Inhibition of this channel is associated with reduced cell migration and proliferation. Using the ASIC-1 subunit as a reporter for the channel complex, we found a physical and functional interaction between this channel and integrin-β1. Short hairpin RNA knockdown of integrin-β1 attenuated the amiloride-sensitive current, which was due to loss of surface expression of ASIC-1. In contrast, upregulation of membrane expression of integrin-β1 increased the surface expression of ASIC-1. The link between the amiloride-sensitive channel and integrin-β1 was mediated by α-actinin. Downregulation of α-actinin-1 or -4 attenuated the amiloride-sensitive current. Mutation of the putative binding site for α-actinin on the COOH terminus of ASIC-1 reduced the membrane localization of ASIC-1 and also resulted in attenuation of the amiloride-sensitive current. Our data suggest a novel interaction between the amiloride-sensitive glioma cation channel and integrin-β1, mediated by α-actinin. This interaction may form a mechanism by which channel activity can regulate glioma cell proliferation and migration. PMID:26108662

Expression patterns of genes encoding plasma membrane aquaporins during fruit development in cucumber (Cucumis sativus L.).

PubMed

Shi, Jin; Wang, Jinfang; Li, Ren; Li, Dianbo; Xu, Fengfeng; Sun, Qianqian; Zhao, Bin; Mao, Ai-Jun; Guo, Yang-Dong

2015-11-01

Aquaporins are membrane channels precisely regulating water movement through cell membranes in most living organisms. Despite the advances in the physiology of fruit development, their participation during fruit development in cucumber still barely understood. In this paper, the expressions of 12 genes encoding plasma membrane intrinsic proteins (PIPs) were analyzed during cucumber fruit development in our work. Based on the homology search with known PIPs from rice, Arabidopsis and strawberry, 12 cucumber PIP genes subfamily members were identified. Cellular localization assays indicated that CsPIPs were localized in the plasma membrane. The qRT-PCR analysis of CsPIPs showed that 12 CsPIPs were differentially expressed during fruit development. These results suggest that 12 genes encoding plasma membrane intrinsic proteins (CsPIPs) play very important roles in cucumber life cycle and the data generated will be helpful in understanding their precise roles during fruit development in cucumber. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Detection and characterisation of multi-drug resistance protein 1 (MRP-1) in human mitochondria

PubMed Central

Roundhill, E A; Burchill, S A

2012-01-01

Background: Overexpression of plasma membrane multi-drug resistance protein 1 (MRP-1) can lead to multidrug resistance. In this study, we describe for the first time the expression of mitochondrial MRP-1 in untreated human normal and cancer cells and tissues. Methods: MRP-1 expression and subcellular localisation in normal and cancer cells and tissues was examined by differential centrifugation and western blotting, and immunofluorescence microscopy. Viable mitochondria were isolated and MRP-1 efflux activity measured using the calcein-AM functional assay. MRP-1 expression was increased using retroviral infection and specific overexpression confirmed by RNA array. Cell viability was determined by trypan blue exclusion and annexin V-propidium iodide labelling of cells. Results: MRP-1 was detected in the mitochondria of cancer and normal cells and tissues. The efflux activity of mitochondrial MRP-1 was more efficient (55–64%) than that of plasma membrane MRP-1 (11–22% P<0.001). Induced MRP-1 expression resulted in a preferential increase in mitochondrial MRP-1, suggesting selective targeting to this organelle. Treatment with a non-lethal concentration of doxorubicin (0.85 n, 8 h) increased mitochondrial and plasma membrane MRP-1, increasing resistance to MRP-1 substrates. For the first time, we have identified MRP-1 with efflux activity in human mitochondria. Conclusion: Mitochondrial MRP-1 may be an exciting new therapeutic target where historically MRP-1 inhibitor strategies have limited clinical success. PMID:22353810

Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the meninges and the choroid plexus: implications for non-neuronal sources for GABA in the developing mouse brain.

PubMed

Tochitani, Shiro; Kondo, Shigeaki

2013-01-01

Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA) is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67), both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11-E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development.

Immunoreactivity for GABA, GAD65, GAD67 and Bestrophin-1 in the Meninges and the Choroid Plexus: Implications for Non-Neuronal Sources for GABA in the Developing Mouse Brain

PubMed Central

Tochitani, Shiro; Kondo, Shigeaki

2013-01-01

Neural progenitors in the developing neocortex, neuroepithelial cells and radial glial cells, have a bipolar shape with a basal process contacting the basal membrane of the meninge and an apical plasma membrane facing the lateral ventricle, which the cerebrospinal fluid is filled with. Recent studies revealed that the meninges and the cerebrospinal fluid have certain roles to regulate brain development. γ-aminobutyric acid (GABA) is a neurotransmitter which appears first during development and works as a diffusible factor to regulate the properties of neural progenitors. In this study, we examined whether GABA can be released from the meninges and the choroid plexus in the developing mouse brain. Immunohistochemical analyses showed that glutamic acid decarboxylase 65 and 67 (GAD65 and GAD67), both of which are GABA-synthesizing enzymes, are expressed in the meninges. The epithelial cells in the choroid plexus express GAD65. GABA immunoreactivity could be observed beneath the basal membrane of the meninge and in the epithelial cells of the choroid plexus. Expression analyses on Bestrophin-1, which is known as a GABA-permeable channel in differentiated glial cells, suggested that the cells in the meninges and the epithelial cells in the choroid plexus have the channels able to permeate non-synaptic GABA into the extracellular space. Further studies showed that GAD65/67-expressing meningeal cells appear in a manner with rostral to caudal and lateral to dorsal gradient to cover the entire neocortex by E14.5 during development, while the cells in the choroid plexus in the lateral ventricle start to express GAD65 on E11–E12, the time when the choroid plexus starts to develop in the developing brain. These results totally suggest that the meninges and the choroid plexus can work as non-neuronal sources for ambient GABA which can modulate the properties of neural progenitors during neocortical development. PMID:23437266

Glucose Transporter 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study.

PubMed

Bandyopadhyay, Alokenath; Panda, Abikshyeet; Behura, Shyam S; Ramachandra, Sujatha; Dash, Kailash C; Mishra, Pallavi

2017-05-01

An array of odontogenic lesions manifest in the maxillofacial region with variable presentations. The biological behavior of lesions, such as odontogenic keratocyst (OKC), dentigerous cyst (DC), and ameloblastoma (AM) always invite debate. Glucose transporter 1 (GLUT-1) is proven to be an indicator of metabolic behavior of several benign and malignant neoplasms. The purpose of this study was to evaluate the expression of GLUT-1 in OKC, DC, and AM to understand their metabolic behavior. Immunohistochemical expression of GLUT-1 was evaluated in each of the 15 cases of OKC, DC, and AM. The number of labeled cells, staining intensity, and membrane or cytoplasmic expressions were the parameters assessed and analyzed using chi-square test. All cases showed positive GLUT-1 expression: 86.6% OKC showed more than 50% labeled cells followed by DC (40%) and AM (26.5%); 53.3% OKC showed strong intensity in comparison to AM, which showed weak intensity in 53.3% cases; 86.6% of OKCs showed both membrane and cytoplasmic expression followed by DC (40%) and AM (26.6%), whereas 73.3% of AM showed only membrane expression followed by DC (60%) and OKC (13.3%). Odontogenic keratocyst was found out to be more metabolically active followed by DC and AM.

Transmembrane transporter expression regulated by the glucosylceramide pathway in Cryptococcus neoformans.

PubMed

Singh, Arpita; Rella, Antonella; Schwacke, John; Vacchi-Suzzi, Caterina; Luberto, Chiara; Del Poeta, Maurizio

2015-11-16

The sphingolipid glucosylceramide (GlcCer) and factors involved in the fungal GlcCer pathways were shown earlier to be an integral part of fungal virulence, especially in fungal replication at 37 °C, in neutral/alkaline pH and 5 % CO2 environments (e.g. alveolar spaces). Two mutants, ∆gcs 1 lacking glucosylceramide synthase 1 gene (GCS1) which catalyzes the formation of sphingolipid GlcCer from the C9-methyl ceramide and ∆smt1 lacking sphingolipid C9 methyltransferase gene (SMT1), which adds a methyl group to position nine of the sphingosine backbone of ceramide, of this pathway were attenuated in virulence and have a growth defect at the above-mentioned conditions. These mutants with either no or structurally modified GlcCer located on the cell-membrane have reduced membrane rigidity, which may have altered not only the physical location of membrane proteins but also their expression, as the pathogen's mode of adaptation to changing need. Importantly, pathogens are known to adapt themselves to the changing host environments by altering their patterns of gene expression. By transcriptional analysis of gene expression, we identified six genes whose expression was changed from their wild-type counterpart grown in the same conditions, i.e. they became either down regulated or up regulated in these two mutants. The microarray data was validated by real-time PCR, which confirmed their fold change in gene expression. All the six genes we identified, viz siderochrome-iron transporter (CNAG_02083), monosaccharide transporter (CNAG_05340), glucose transporter (CNAG_03772), membrane protein (CNAG_03912), membrane transport protein (CNAG_00539), and sugar transporter (CNAG_06963), are membrane-localized and have significantly altered gene expression levels. Therefore, we hypothesize that these genes function either independently or in tandem with a structurally modified cell wall/plasma membrane resulting from the modifications of the GlcCer pathway and thus possibly disrupt transmembrane signaling complex, which in turn contributes to cryptococcal osmotic, pH, ion homeostasis and its pathobiology. Six genes identified from gene expression microarrays by gene set enrichment analysis and validated by RT-PCR, are membrane located and associated with the growth defect at neutral-alkaline pH due to the absence and or presence of a structurally modified GlcCer. They may be involved in the transmembrane signaling network in Cryptococcus neoformans, and therefore the pathobiology of the fungus in these conditions.

Na+/H+ exchange regulatory factor 1 is required for ROMK1 K+ channel expression in the surface membrane of cultured M-1 cortical collecting duct cells.

PubMed

Suzuki, Takashi; Nakamura, Kazuyoshi; Mayanagi, Taira; Sobue, Kenji; Kubokawa, Manabu

2017-07-22

The ROMK1 K + channel, a member of the ROMK channel family, is the major candidate for the K + secretion pathway in the renal cortical collecting duct (CCD). ROMK1 possesses a PDZ domain-binding motif at its C-terminus that is considered a modulator of ROMK1 expression via interaction with Na + /H + exchange regulatory factor (NHERF) 1 and NHERF2 scaffold protein. Although NHERF1 is a potential binding partner of the ROMK1 K + channel, the interaction between NHERF1 and K + channel activity remains unclear. Therefore, in this study, we knocked down NHERF1 in cultured M-1 cells derived from mouse CCD and investigated the surface expression and K + channel current in these cells after exogenous transfection with EGFP-ROMK1. NHERF1 knockdown resulted in reduced surface expression of ROMK1 as indicated by a cell biotinylation assay. Using the patch-clamp technique, we further found that the number of active channels per patched membrane and the Ba 2+ -sensitive whole-cell K + current were decreased in the knockdown cells, suggesting that reduced K + current was accompanied by decreased surface expression of ROMK1 in the NHERF1 knockdown cells. Our results provide evidence that NHERF1 mediates K + current activity through acceleration of the surface expression of ROMK1 K + channels in M-1 cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Cell Surface Expression of Biologically Active Influenza C Virus HEF Glycoprotein Expressed from cDNA

PubMed Central

Pekosz, Andrew; Lamb, Robert A.

1999-01-01

The hemagglutinin, esterase, and fusion (HEF) glycoprotein of influenza C virus possesses receptor binding, receptor destroying, and membrane fusion activities. The HEF cDNAs from influenza C/Ann Arbor/1/50 (HEF-AA) and influenza C/Taylor/1223/47 (HEF-Tay) viruses were cloned and expressed, and transport of HEF to the cell surface was monitored by susceptibility to cleavage by exogenous trypsin, indirect immunofluorescence microscopy, and flow cytometry. Previously it has been found in studies with the C/Johannesburg/1/66 strain of influenza C virus (HEF-JHB) that transport of HEF to the cell surface is severely inhibited, and it is thought that the short cytoplasmic tail, Arg-Thr-Lys, is involved in blocking HEF cell surface expression (F. Oeffner, H.-D. Klenk, and G. Herrler, J. Gen. Virol. 80:363–369, 1999). As the cytoplasmic tail amino acid sequences of HEF-AA and HEF-Tay are identical to that of HEF-JHB, the data indicate that cell surface expression of HEF-AA and HEF-Tay is not inhibited by this amino acid sequence. Furthermore, the abundant cell surface transport of HEF-AA and HEF-Tay indicates that their cell surface expression does not require coexpression of another viral protein. The HEF-AA and HEF-Tay HEF glycoproteins bound human erythrocytes, promoted membrane fusion in a low-pH and trypsin-dependent manner, and displayed esterase activity, indicating that the HEF glycoprotein alone mediates all three known functions at the cell surface. PMID:10482635

Expression of solute carrier 7A4 (SLC7A4) in the plasma membrane is not sufficient to mediate amino acid transport activity.

PubMed

Wolf, Sabine; Janzen, Annette; Vékony, Nicole; Martiné, Ursula; Strand, Dennis; Closs, Ellen I

2002-06-15

Member 4 of human solute carrier family 7 (SLC7A4) exhibits significant sequence homology with the SLC7 subfamily of human cationic amino acid transporters (hCATs) [Sperandeo, Borsani, Incerti, Zollo, Rossi, Zuffardi, Castaldo, Taglialatela, Andria and Sebastio (1998) Genomics 49, 230-236]. It is therefore often referred to as hCAT-4 even though no convincing transport activity has been shown for this protein. We expressed SLC7A4 in Xenopus laevis oocytes, but could not detect any transport activity for cationic, neutral or anionic amino acids or for the polyamine putrescine. In addition, human glioblastoma cells stably overexpressing a fusion protein between SLC7A4 and the enhanced green fluorescent protein (EGFP) did not exhibit an increased transport activity for l-arginine. The lack of transport activity was not due to a lack of SLC7A4 protein expression in the plasma membrane, as in both cell types SLC7A4-EGFP exhibited a similar subcellular localization and level of protein expression as functional hCAT-EGFP proteins. The expression of SLC7A4 can be induced in NT2 teratocarcinoma cells by treatment with retinoic acid. However, also for this endogenously expressed SLC7A4, we could not detect any transport activity for l-arginine. Our data demonstrate that the expression of SLC7A4 in the plasma membrane is not sufficient to induce an amino acid transport activity in X. laevis oocytes or human cells. Therefore, SLC7A4 is either not an amino acid transporter or it needs additional (protein) factor(s) to be functional.

Expression of solute carrier 7A4 (SLC7A4) in the plasma membrane is not sufficient to mediate amino acid transport activity.

PubMed Central

Wolf, Sabine; Janzen, Annette; Vékony, Nicole; Martiné, Ursula; Strand, Dennis; Closs, Ellen I

2002-01-01

Member 4 of human solute carrier family 7 (SLC7A4) exhibits significant sequence homology with the SLC7 subfamily of human cationic amino acid transporters (hCATs) [Sperandeo, Borsani, Incerti, Zollo, Rossi, Zuffardi, Castaldo, Taglialatela, Andria and Sebastio (1998) Genomics 49, 230-236]. It is therefore often referred to as hCAT-4 even though no convincing transport activity has been shown for this protein. We expressed SLC7A4 in Xenopus laevis oocytes, but could not detect any transport activity for cationic, neutral or anionic amino acids or for the polyamine putrescine. In addition, human glioblastoma cells stably overexpressing a fusion protein between SLC7A4 and the enhanced green fluorescent protein (EGFP) did not exhibit an increased transport activity for l-arginine. The lack of transport activity was not due to a lack of SLC7A4 protein expression in the plasma membrane, as in both cell types SLC7A4-EGFP exhibited a similar subcellular localization and level of protein expression as functional hCAT-EGFP proteins. The expression of SLC7A4 can be induced in NT2 teratocarcinoma cells by treatment with retinoic acid. However, also for this endogenously expressed SLC7A4, we could not detect any transport activity for l-arginine. Our data demonstrate that the expression of SLC7A4 in the plasma membrane is not sufficient to induce an amino acid transport activity in X. laevis oocytes or human cells. Therefore, SLC7A4 is either not an amino acid transporter or it needs additional (protein) factor(s) to be functional. PMID:12049641

Shape Changes and Interaction Mechanism of Escherichia coli Cells Treated with Sericin and Use of a Sericin-Based Hydrogel for Wound Healing

PubMed Central

Xue, Rui; Liu, Yalong; Liang, Congcong; Qin, Huazhen; Liu, Pengfei; Wang, Ke; Zhang, Xiaoyong; Chen, Li

2016-01-01

ABSTRACT To verify the interaction mechanism between sericin and Escherichia coli, especially the morphological and structural changes in the bacterial cells, the antimicrobial activity of sericin against E. coli as a model for Gram-negative bacteria was investigated. The antibacterial activity of sericin on E. coli and the interaction mechanism were investigated in this study by analyzing the growth, integrity, and morphology of the bacterial cells following treatment with sericin. The changes in morphology and cellular compositions of bacterial cells treated with sericin were observed by an inverted fluorescence microscope, scanning electron microscopy, and transmission electron microscopy. Changes in electrical conductivity, total sugar concentration of the broth for the bacteria, and protein expression of the bacteria were determined to investigate the permeability of the cell membrane. A sericin-based hydrogel was prepared for an in vivo study of wound dressing. The results showed that the antibacterial activity of the hydrogel increased with the increase in the concentration of sericin from 10 g/liter to 40 g/liter. The introduction of sericin induces membrane blebbing of E. coli cells caused by antibiotic action on the cell membrane. The cytoplasm shrinkage phenomenon was accompanied by blurring of the membrane wall boundaries. When E. coli cells were treated with sericin, release of intracellular components quickly increased. The electrical conductivity assay indicated that the charged ions are reduced after exposure to sericin so that the integrity of the cell membrane is weakened and metabolism is blocked. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that sericin hinders the expression of bacterial protein. Sericin may damage the integrity of the bacterial cell membrane, thereby eventually inhibiting the growth and reproduction of E. coli. Compared to sterile gauze, the sericin-based hydrogel promoted fibroblast cell proliferation and accelerated the formation of granulation tissues and neovessels. IMPORTANCE The specific relationship and interaction mechanism between sericin and E. coli cells were investigated and elucidated. The results show that after 12 h of treatment, sericin molecules induce membrane blebbing of E. coli cells, and the bacteria show decreases in liquidity and permeability of biological membrane, resulting in alterations in the conductivity of the culture medium and the integrity of the outer membrane. The subsequent in vivo results demonstrate that the sericin-poly(N-isopropylacrylamide-N,N′-methylene-bis-acrylamide [NIPAm-MBA]) hydrogel accelerated wound healing compared to that with sterile gauze, which is a beneficial result for future applications in clinical medicine and the textile, food, and coating industries. PMID:27235427

LAMP-2C Inhibits MHC Class II Presentation of Cytoplasmic Antigens by Disrupting Chaperone-Mediated Autophagy.

PubMed

Pérez, Liliana; McLetchie, Shawna; Gardiner, Gail J; Deffit, Sarah N; Zhou, Delu; Blum, Janice S

2016-03-15

Cells use multiple autophagy pathways to sequester macromolecules, senescent organelles, and pathogens. Several conserved isoforms of the lysosome-associated membrane protein-2 (LAMP-2) regulate these pathways influencing immune recognition and responses. LAMP-2A is required for chaperone-mediated autophagy (CMA), which promotes Ag capture and MHC class II (MHCII) presentation in B cells and signaling in T cells. LAMP-2B regulates lysosome maturation to impact macroautophagy and phagocytosis. Yet, far less is known about LAMP-2C function. Whereas LAMP2A and LAMP2B mRNA were broadly detected in human tissues, LAMP2C expression was more limited. Transcripts for the three LAMP2 isoforms increased with B cell activation, although specific gene induction varied depending on TLR versus BCR engagement. To examine LAMP-2C function in human B cells and specifically its role in Ag presentation, we used ectopic gene expression. Increased LAMP-2C expression in B cells did not alter MHCII expression or invariant chain processing, but did perturb cytoplasmic Ag presentation via CMA. MHCII presentation of epitopes from exogenous and membrane Ags was not affected by LAMP-2C expression in B cells. Similarly, changes in B cell LAMP-2C expression did not impact macroautophagy. The gene expression of other LAMP2 isoforms and proteasome and lysosomal proteases activities were unperturbed by LAMP-2C ectopic expression. LAMP-2C levels modulated the steady-state expression of several cytoplasmic proteins that are targeted for degradation by CMA and diminished peptide translocation via this pathway. Thus, LAMP-2C serves as a natural inhibitor of CMA that can selectively skew MHCII presentation of cytoplasmic Ags. Copyright © 2016 by The American Association of Immunologists, Inc.

LAMP-2C inhibits MHC class II presentation of cytoplasmic antigens by disrupting chaperone-mediated autophagy

PubMed Central

Pérez, Liliana; McLetchie, Shawna; Gardiner, Gail J.; Deffit, Sarah N.; Zhou, Delu; Blum, Janice S.

2016-01-01

Cells utilize multiple autophagy pathways to sequester macromolecules, senescent organelles, and pathogens. Several conserved isoforms of the lysosome-associated membrane protein (LAMP)-2 regulate these pathways influencing immune recognition and responses. LAMP-2A is required for chaperone-mediated autophagy (CMA) which promotes Ag capture and MHC class II (MHCII) presentation in B cells and signaling in T cells. LAMP-2B regulates lysosome maturation to impact macroautophagy (MA) and phagocytosis. Yet, far less is known about LAMP-2C function. While LAMP2A and LAMP2B mRNA were broadly detected in human tissues, LAMP2C expression was more limited. Transcripts for the three LAMP2 isoforms increased with B cell activation, although specific gene induction varied depending on TLR versus BCR engagement. To examine LAMP-2C function in human B cells and specifically its role in Ag presentation, ectopic gene expression was used. Increased LAMP-2C expression in B cells did not alter MHCII expression or invariant chain processing, but did perturb cytoplasmic Ag presentation via CMA. MHCII presentation of epitopes from exogenous and membrane Ags was not affected by LAMP-2C expression in B cells. Similarly, changes in B cell LAMP-2C expression did not impact MA. The gene expression of other LAMP2 isoforms as well as the proteasome and lysosomal proteases activities were unperturbed by LAMP-2C ectopic expression. LAMP-2C levels modulated the steady-state expression of several cytoplasmic proteins which are targeted for degradation by CMA and diminished peptide translocation via this pathway. Thus, LAMP-2C serves as a natural inhibitor of CMA which can selectively skew MHCII presentation of cytoplasmic Ags. PMID:26856698

Diffusion mediated localization on membrane surfaces

NASA Technical Reports Server (NTRS)

Weaver, D. L.

1982-01-01

Using the model of a cell membrane of a spherical surface in which membrane components may diffuse, the rate of localization due to trapping under diffusion control has been estimated by computing an analytical expression for the mean trapping time including the possibilities of a trapping probability less than one and/or the establishment of an equilibrium at the trap boundary.

Proteomic analysis of plasma membranes isolated from undifferentiated and differentiated HepaRG cells

PubMed Central

2012-01-01

Liver infection with hepatitis B virus (HBV), a DNA virus of the Hepadnaviridae family, leads to severe disease, such as fibrosis, cirrhosis and hepatocellular carcinoma. The early steps of the viral life cycle are largely obscure and the host cell plasma membrane receptors are not known. HepaRG is the only proliferating cell line supporting HBV infection in vitro, following specific differentiation, allowing for investigation of new host host-cell factors involved in viral entry, within a more robust and reproducible environment. Viral infection generally begins with receptor recognition at the host cell surface, following highly specific cell-virus interactions. Most of these interactions are expected to take place at the plasma membrane of the HepaRG cells. In the present study, we used this cell line to explore changes between the plasma membrane of undifferentiated (−) and differentiated (+) cells and to identify differentially-regulated proteins or signaling networks that might potentially be involved in HBV entry. Our initial study identified a series of proteins that are differentially expressed in the plasma membrane of (−) and (+) cells and are good candidates for potential cell-virus interactions. To our knowledge, this is the first study using functional proteomics to study plasma membrane proteins from HepaRG cells, providing a platform for future experiments that will allow us to understand the cell-virus interaction and mechanism of HBV viral infection. PMID:22857383

[6]-Shogaol, a dietary phenolic compound, induces oxidative stress mediated mitochondrial dependant apoptosis through activation of proapoptotic factors in Hep-2 cells.

PubMed

Annamalai, Govindhan; Kathiresan, Suresh; Kannappan, Nagappan

2016-08-01

Ginger (Zingiber officinale) is a well-known herb used in ethnomedicine. [6]-shogaol, a phenolic nature is a major constituent of ginger. In this study, we investigated the anticancer activity of [6]-shogaol in Laryngeal cancer (Hep-2) cells. We demonstrated the effects of [6]-shogaol on the cell growth and apoptosis in Hep-2 cells were analyzed by the generation of reactive oxygen species (ROS), the level of mitochondrial membrane potential (ΔYm), DNA damage and apoptotic morphological changes were analyzed by AO/EtBr, AO and Hoechst staining. Further, apoptotic protein expressions were analyzed by western blot analysis. Our results indicated that [6]-shogaol induces apoptosis as evidenced by loss of cell viability, enhanced ROS, lipid peroxidation results in altered mitochondrial membrane potential, increased DNA damage in Hep-2 cells. Further, the prooxidant role of [6]-shogaol inhibit Bcl-2 expression with the simultaneous up-regulation of Bax, Cytochrome c, Caspase-9 and -3 protein expressions were observed in Hep-2 cells. Thus, [6]-shogaol induces apoptosis in Hep-2 cells through inducing oxidative damage and modulate apoptotic marker expressions. Therefore, [6]-shogaol might be used as a therapeutic agent for the treatment of laryngeal cancer. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Lipid Requirements for the Enzymatic Activity of MraY Translocases and in Vitro Reconstitution of the Lipid II Synthesis Pathway*

PubMed Central

Henrich, Erik; Ma, Yi; Engels, Ina; Münch, Daniela; Otten, Christian; Schneider, Tanja; Henrichfreise, Beate; Sahl, Hans-Georg; Dötsch, Volker; Bernhard, Frank

2016-01-01

Screening of new compounds directed against key protein targets must continually keep pace with emerging antibiotic resistances. Although periplasmic enzymes of bacterial cell wall biosynthesis have been among the first drug targets, compounds directed against the membrane-integrated catalysts are hardly available. A promising future target is the integral membrane protein MraY catalyzing the first membrane associated step within the cytoplasmic pathway of bacterial peptidoglycan biosynthesis. However, the expression of most MraY homologues in cellular expression systems is challenging and limits biochemical analysis. We report the efficient production of MraY homologues from various human pathogens by synthetic cell-free expression approaches and their subsequent characterization. MraY homologues originating from Bordetella pertussis, Helicobacter pylori, Chlamydia pneumoniae, Borrelia burgdorferi, and Escherichia coli as well as Bacillus subtilis were co-translationally solubilized using either detergent micelles or preformed nanodiscs assembled with defined membranes. All MraY enzymes originating from Gram-negative bacteria were sensitive to detergents and required nanodiscs containing negatively charged lipids for obtaining a stable and functionally folded conformation. In contrast, the Gram-positive B. subtilis MraY not only tolerates detergent but is also less specific for its lipid environment. The MraY·nanodisc complexes were able to reconstitute a complete in vitro lipid I and lipid II forming pipeline in combination with the cell-free expressed soluble enzymes MurA-F and with the membrane-associated protein MurG. As a proof of principle for future screening platforms, we demonstrate the inhibition of the in vitro lipid II biosynthesis with the specific inhibitors fosfomycin, feglymycin, and tunicamycin. PMID:26620564

The expression and function of epithelial membrane protein 1 in laryngeal carcinoma.

PubMed

Li, Hong; Zhang, Xiaowen; Jiang, Xuejun; Ji, Xu

2017-01-01

In this study, we compared the expression of epithelial membrane protein 1 (EMP1) on the steady-state mRNA level (by quantitative real-time PCR) and on the protein level (by western immunoblot and immunohistochemistry) in 51 pairs of laryngeal carcinoma tissues and matched cancer-free peritumor tissues, and we analyzed the correlation between EMP1 expression and different clinicopathological factors. Furthermore, we ectopically expressed EMP1 in human laryngeal carcinoma Hep-2 cells and examined the effects on cell viability, apoptosis, colonogenicity, and motility, by MTT assay, flow cytometry, colony formation assay and Transwell migration assay, respectively. EMP1 expression (on both the mRNA and protein levels) was significantly lower in the cancer tissues than in matched peritumor tissues (P<0.05). In laryngeal cancers, the level of EMP1 protein was correlated with histological grade (P<0.05), but not with age, gender, clinical stage, cancer subtype or lymph node metastasis (P>0.05). Functionally, ectopic expression of EMP1 in Hep-2 cells significantly reduced cell viability, colony formation, and migration, but enhanced apoptosis. Therefore, EMP1 is a tumor suppressor in laryngeal carcinoma. Boosting EMP1 expression in laryngeal carcinoma initiates multiple anticancer phenotypes and thus presents a promising therapeutic strategy for laryngeal cancer.

Hypoxic stress up-regulates Kir2.1 expression and facilitates cell proliferation in brain capillary endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamura, Hideto; Suzuki, Yoshiaki; Yamamura, Hisao

The blood-brain barrier (BBB) is mainly composed of brain capillary endothelial cells (BCECs), astrocytes and pericytes. Brain ischemia causes hypoxic encephalopathy and damages BBB. However, it remains still unclear how hypoxia affects BCECs. In the present study, t-BBEC117 cells, an immortalized bovine brain endothelial cell line, were cultured under hypoxic conditions at 4–5% oxygen for 72 h. This hypoxic stress caused hyperpolarization of resting membrane potential. Patch-clamp recordings revealed a marked increase in Ba{sup 2+}-sensitive inward rectifier K{sup +} current in t-BBEC117 cells after hypoxic culture. Western blot and real-time PCR analyses showed that Kir2.1 expression was significantly up-regulated at protein level butmore » not at mRNA level after the hypoxic culture. Ca{sup 2+} imaging study revealed that the hypoxic stress enhanced store-operated Ca{sup 2+} (SOC) entry, which was significantly reduced in the presence of 100 μM Ba{sup 2+}. On the other hand, the expression of SOC channels such as Orai1, Orai2, and transient receptor potential channels was not affected by hypoxic stress. MTT assay showed that the hypoxic stress significantly enhanced t-BBEC117 cell proliferation, which was inhibited by approximately 60% in the presence of 100 μM Ba{sup 2+}. We first show here that moderate cellular stress by cultivation under hypoxic conditions hyperpolarizes membrane potential via the up-regulation of functional Kir2.1 expression and presumably enhances Ca{sup 2+} entry, resulting in the facilitation of BCEC proliferation. These findings suggest potential roles of Kir2.1 expression in functional changes of BCECs in BBB following ischemia. -- Highlights: •Hypoxic culture of brain endothelial cells (BEC) caused membrane hyperpolarization. •This hyperpolarization was due to the increased expression of Kir2.1 channels. •Hypoxia enhanced store-operated Ca{sup 2+} (SOC) entry via Kir2.1 up-regulation. •Expression levels of putative SOC channels were not affected by hypoxia. •Kir2.1 up-regulation is responsible for hypoxia-enhanced BEC proliferation.« less

Expression of GLUT-1 in oral squamous cell carcinoma in tobacco and non-tobacco users

PubMed Central

Azad, Neha; Kumari Maurya, Malti; Kar, Meenakshi; Goel, Madhu Mati; Singh, Ajay Kumar; Sagar, Mala; Mehrotra, Divya; Kumar, Vijay

2016-01-01

Background GLUTs are a family of proteins that mediate glucose transport through the membrane, expressed in head and neck squamous cell carcinoma. GLUT-1 positivity in malignant cells indicates increased proliferative activity, energy requirements, aggressive behaviour and poor radiation response. Aim To observe the expression of GLUT-1 protein in oral squamous cell carcinoma in tobacco and non-tobacco users and to correlate the expression with histopathological grading and pathological staging. Methods 50 cases (25 tobacco and 25 non-tobacco) of oral squamous cell carcinoma, selected during period of August 2014 to July 2015. Histopathological grading, TNM and staging were done. Immunohistochemical staining was performed using standard protocol for paraffin embedded sections. Analysis was performed on SPSS software (Windows version 17.0). Results Significant association of GLUT-1 expression was found with history of tobacco (p < 0.001), Bryne's grade (p < 0.001), tumour size (p = 0.001), nodal metastasis (p = 0.022) and stage (p < 0.001). Higher GLUT-1 expression in stage II, stage III and stage IV was found as compared to stage I. GLUT-1 immunoexpression also shows progressive switch from membranous to cytoplasmic to combined location correlating with histopathologic grade and pTNM stage. Conclusion GLUT-1 expression correlates significantly with histological grade and pTNM staging of oral squamous cell carcinoma. It also significantly correlates with tobacco addiction. Thus, GLUT-1 expression may serve as a biomarker for patients of oral squamous cell carcinoma. PMID:26937365

Comparison of ultrastructure, tight junction-related protein expression and barrier function of human corneal epithelial cells cultivated on amniotic membrane with and without air-lifting.

PubMed

Ban, Yuriko; Cooper, Leanne J; Fullwood, Nigel J; Nakamura, Takahiro; Tsuzuki, Masakatsu; Koizumi, Noriko; Dota, Atsuyoshi; Mochida, Chikako; Kinoshita, Shigeru

2003-06-01

To evaluate the usefulness of the air-lifting technique for culturing corneal limbal epithelial cells on amniotic membrane (AM) for use in ocular surface reconstruction. A cultured sheet that has a good barrier function should be better for this purpose. In corneal epithelium, tight junctions (TJ) play a vital role in the barrier function. The TJ complex includes the integral transmembrane proteins occludin and the claudins, and some membrane-associated proteins such as ZO-1. In this paper, we investigated the barrier function and the expression of TJ related proteins. Corneal limbal epithelium obtained from donor corneas and cultivated on acellular AM was divided into two groups. These were the non-air-lifting (Non-AL) group, which was continuously submerged in medium, and the air-lifting (AL) group, which was submerged in medium for 3 weeks, then exposed to air by lowering the medium level. Morphology and the permeability to horseradish peroxidase (HRP) were determined by electron microscopy. Tight junction (TJ)-related protein and mRNA expression changes were assessed by immunoblotting and reverse transcription-polymerase chain reaction. The cultures of both groups formed 4-5-layer-thick, well-stratified epithelium. The AL cultures had tightly packed epithelial cells with all the HRP/diaminobenzidine (DAB) reaction product accumulated on the apical surface of the superficial cells. The Non-AL culture, by contrast, had more loosely packed epithelial cells with larger intercellular spaces. The HRP/DAB reaction product penetrated the intercellular space to a depth of 3-4 cell layers. Statistically, there was a significant difference in intercellular spaces and desmosome count in the superficial cells between the groups. With AL, TJ-related proteins localized at the apical portion of the lateral membrane. TJ-related protein and mRNA amounts were not changed by AL while claudin subtype expression became more consistent and closer to that of in vivo corneal epithelium. The AL technique reduces intercellular spaces in the superficial cells and promotes the formation of the barrier function. It is useful in culturing corneal epithelial cells for use in ocular surface reconstruction.

CEACAM1 is overexpressed in oral tumors and related to tumorigenesis.

PubMed

Wang, Fu-Fang; Guan, Bing-Xin; Yang, Jing-Yan; Wang, Hai-Tao; Zhou, Cheng-Jun

2017-03-01

Carcinoembryonic antigen-related adhesion molecule 1 (CEACAM1) is a type 1 transmembrane glycoprotein belonging to the CEA family, which has been known to exist as either soluble forms in body fluids or membrane-bound forms on the cell surface. Aberrant CEACAM1 expression is associated with tumorigenesis and has been reported in a variety of human tumors, especially malignancies. The aim of this study is to determine the expression of CEACAM1 in oral tumors, trying to study CEACAM1 different expressions as a function of histotype. CEACAM1 expression was observed by immunohistochemistry (IHC) with mouse anti-human antibody for CEACAM1. IHC was performed using avidin-biotin-diaminobenzidine staining. The results were expressed as average score ± SD (0 = negative/8 = highest) for each histotype. Oral tumors expressed more CEACAM1 than normal tissues including squamous and salivary epithelia (P < 0.05). In malignancies, the squamous cell carcinoma overexpressed CEACAM1, compared to well-differentiated squamous cell with more membranous expression; the intermediately and poorly differentiated squamous cell carcinoma showed more cytoplasmic expression (P < 0.05). In addition, the salivary tumors significantly expressed more CEACAM1 than squamous cell carcinoma (P < 0.05). So, we thought oral tumors overexpressed CEACAM1 and the cytoplasmic CEACAM1 might be involved in tumorigenesis, and also CEACAM1 might be regarded as a marker of salivary glandular tumors.

Matrix-specific protein kinase A signaling regulates p21 activated kinase activation by flow in endothelial cells

PubMed Central

Funk, Steven Daniel; Yurdagul, Arif; Green, Jonette M.; Jhaveri, Krishna A.; Schwartz, Martin Alexander; Orr, A. Wayne

2010-01-01

Rationale Atherosclerosis is initiated by blood flow patterns that activate inflammatory pathways in endothelial cells. Activation of inflammatory signaling by fluid shear stress is highly dependent on the composition of the subendothelial extracellular matrix. The basement membrane proteins laminin and collagen found in normal vessels suppress flow-induced p21 activated kinase (PAK) and NF-κB activation. By contrast, the provisional matrix proteins fibronectin and fibrinogen found in wounded or inflamed vessels support flow-induced PAK and NF-κB activation. PAK mediates both flow-induced permeability and matrix-specific activation of NF-κB. Objective To elucidate the mechanisms regulating matrix-specific PAK activation. Methods and Results We now show that matrix composition does not affect the upstream pathway by which flow activates PAK (integrin activation, Rac). Instead basement membrane proteins enhance flow-induced protein kinase A (PKA) activation, which suppresses PAK. Inhibiting PKA restored flow-induced PAK and NF-κB activation in cells on basement membrane proteins, whereas stimulating PKA inhibited flow-induced activation of inflammatory signaling in cells on fibronectin. PKA suppressed inflammatory signaling through PAK inhibition. Activating PKA by injection of the PGI2 analog iloprost reduced PAK activation and inflammatory gene expression at sites of disturbed flow in vivo, whereas inhibiting PKA by PKI injection enhanced PAK activation and inflammatory gene expression. Inhibiting PAK prevented the enhancement of inflammatory gene expression by PKI. Conclusions Basement membrane proteins inhibit inflammatory signaling in endothelial cells via PKA-dependent inhibition of PAK. PMID:20224042

Increased curvature of hollow fiber membranes could up-regulate differential functions of renal tubular cell layers.

PubMed

Shen, Chong; Meng, Qin; Zhang, Guoliang

2013-08-01

Tissue engineering devices as in vitro cell culture systems in scaffolds has encountered the bottleneck due to their much lower cell functions than real tissues/organs in vivo. Such situation has been improved in some extent by mimicking the cell microenvironments in vivo from either chemical or physical ways. However, microenvironmental curvature, commonly seen in real tissues/organs, has never been manipulated to regulate the cell performance in vitro. In this regard, this paper fabricated polysulfone membranes with or without polyethylene glycol modification to investigate the impact of curvature on two renal tubular cells. Regardless the varying membrane curvatures among hollow fiber membranes of different diameters and flat membrane of zero curvature, both renal cells could well attach at 4 h of seeding and form similar confluent layers at 6 days on each membrane. Nevertheless, the renal cells on hollow fibers, though showing confluent morphology as those on flat membranes, expressed higher renal functions and, moreover, the renal functions significantly increased with the membrane curvature among hollow fibers. Such upregulation on functions was unassociated with mass transport barrier of hollow fibers, because the cultures on lengthwise cut hollow fibers without mass transfer barrier showed same curvature effect on renal functions as whole hollow fibers. It could be proposed that the curvature of hollow fiber membrane approaching to the large curvature in kidney tubules increased the mechanical stress in the renal cells and thus might up-regulate the renal cell functions. In conclusion, the increase of substrate curvature could up-regulate the cell functions without altering the confluent cell morphology and this finding will facilitate the design of functional tissue engineering devices. Copyright © 2013 Wiley Periodicals, Inc.

Expression of intercellular adhesion molecule-1 by myofibers in mdx mice.

PubMed

Torres-Palsa, Maria J; Koziol, Matthew V; Goh, Qingnian; Cicinelli, Peter A; Peterson, Jennifer M; Pizza, Francis X

2015-11-01

We investigated the extent to which intercellular adhesion molecule-1 (ICAM-1), a critical protein of the inflammatory response, is expressed in skeletal muscles of mdx mice (a murine model of Duchenne muscular dystrophy). Muscles were collected from control and mdx mice at 2-24 weeks of age and analyzed for ICAM-1 expression by means of Western blot and immunofluorescence. Western blot revealed higher expression of ICAM-1 in mdx compared with control muscles through 24 weeks of age. In contrast to control muscles, ICAM-1 was expressed on the membrane of damaged, regenerating, and normal myofibers of mdx mice. CD11b+ myeloid cells also expressed ICAM-1 in mdx muscles, and CD11b+ cells were closely associated with the membrane of myofibers expressing ICAM-1. These findings support a paradigm in which ICAM-1 and its localization to myofibers in muscles of mdx mice contributes to the dystrophic pathology. © 2015 Wiley Periodicals, Inc.

EXPRESSION OF INTERCELLULAR ADHESION MOLECULE-1 BY MYOFIBERS IN mdx MICE

PubMed Central

TORRES-PALSA, MARIA J.; KOZIOL, MATTHEW V.; GOH, QINGNIAN; CICINELLI, PETER A.; PETERSON, JENNIFER M.; PIZZA, FRANCIS X.

2017-01-01

Introduction We investigated the extent to which intercellular adhesion molecule-1 (ICAM-1), a critical protein of the inflammatory response, is expressed in skeletal muscles of mdx mice (a murine model of Duchenne muscular dystrophy). Methods Muscles were collected from control and mdx mice at 2–24 weeks of age and analyzed for ICAM-1 expression by means of Western blot and immunofluorescence. Results Western blot revealed higher expression of ICAM-1 in mdx compared with control muscles through 24 weeks of age. In contrast to control muscles, ICAM-1 was expressed on the membrane of damaged, regenerating, and normal myofibers of mdx mice. CD11b+ myeloid cells also expressed ICAM-1 in mdx muscles, and CD11b+ cells were closely associated with the membrane of myofibers expressing ICAM-1. Conclusions These findings support a paradigm in which ICAM-1 and its localization to myofibers in muscles of mdx mice contributes to the dystrophic pathology. PMID:25728314

Nuclear localization of Klotho in brain: an anti-aging protein

PubMed Central

German, Dwight C.; Khobahy, Ida; Pastor, Johanne; Kuro-o, Makoto; Liu, Xinran

2011-01-01

Klotho is a putative age-suppressing gene whose over-expression in mice results in extension of life span. The klotho gene encodes a single-pass transmembrane protein whose extracellular domain is shed and released into blood, urine, and cerebrospinal fluid, potentially functioning as a humoral factor. The extracellular domain of Klotho has an activity that increases the expression of anti-oxidant enzymes and confers resistance to oxidative stress in cultured cells and in whole animals. The transmembrane form of the Klotho protein directly binds to multiple fibroblast growth factor receptors and modifies their ligand affinity and specificity. The purpose of the present study was to determine the precise cellular localization of Klotho in the mouse brain. Using light microscopic immunohistochemical methods, we found the highest levels of Klotho immunoreactivity in two brain regions: the choroid plexus, and cerebellar Purkinje cells. In the choroid plexus cells, Klotho was found not only on the plasma membrane but also in large amounts near the nuclear membrane. Likewise, in the Purkinje cell Klotho was found throughout the cell including dendrites, axon and soma with large amounts near the nuclear membrane. Using immunoelectron microscopy, we found Klotho in the cell membrane, but the highest concentration was localized in the peripheral portion of the nucleus and the nucleolus in both cell types. This new finding suggests that in addition to Klotho being secreted from cells in brain, it also has a nuclear function. PMID:22245317

Membrane transport mechanisms of choline in human intestinal epithelial LS180 cells.

PubMed

Horie, Asuka; Ishida, Kazuya; Watanabe, Yuri; Shibata, Kaito; Hashimoto, Yukiya

2014-12-01

The aim of the present study was to investigate the membrane transport mechanisms of choline using human intestinal epithelial LS180 cells. The mRNA of choline transporter-like proteins (CTLs) was expressed significantly in LS180 cells, and the rank order was CTL1 > CTL4 > CTL3 > CTL2 > CTL5. In contrast, the mRNA expression of other choline transporters, organic cation transporter (OCT) 1, OCT2 and high-affinity choline transporter 1 (CHT1), was considerably lower in LS180 cells. Five mm unlabelled choline, hemicolinium-3 and guanidine, but not tetraethylammonium, inhibited the cellular uptake of 100 µm choline in LS180 cells. The uptake of choline into LS180 cells was virtually Na(+)-independent. The uptake of choline was significantly decreased by acidification of the extracellular pH; however, it was not increased by alkalization of the extracellular pH. In addition, both acidification and alkalization of intracellular pH decreased the uptake of choline, indicating that the choline uptake in LS180 cells is not stimulated by the outward H(+) gradient. On the other hand, the uptake of choline was decreased by membrane depolarization along with increasing extracellular K(+) concentration. In addition, the Na(+)-independent uptake of choline was saturable, and the Km value was estimated to be 108 µm. These findings suggest that the uptake of choline into LS180 cells is membrane potential-dependent, but not outward H(+) gradient-dependent. Copyright © 2014 John Wiley & Sons, Ltd.

Aldosterone Upregulates Transient Receptor Potential Melastatin 7 (TRPM7)*

PubMed Central

Valinsky, William C.; Jolly, Anna; Miquel, Perrine

2016-01-01

Transient receptor potential melastatin 7 (TRPM7) is a ubiquitously expressed Mg2+-permeable ion channel fused to a C-terminal α-kinase domain. Recently, aldosterone was shown to increase intracellular Mg2+ levels and alter inflammatory signaling in TRPM7-expressing HEK293 cells. This study was undertaken to assess whether these effects were related to an aldosterone-mediated increase of TRPM7 current and/or plasma membrane localization. Using HEK293 cells stably expressing WT-TRPM7, we found that 18-h application of aldosterone significantly increased TRPM7 current and TRPM7 plasma membrane protein expression by 48% and 34%, respectively. The aldosterone-mediated increase of TRPM7 current was inhibited by eplerenone, a mineralocorticoid receptor (MR) blocker, and GSK-650394, an inhibitor of the serum- and glucocorticoid-regulated kinase 1 (SGK1). SGK1 blockade also prevented the aldosterone-induced increase of TRPM7 plasma membrane protein. It was further determined that K1648R-TRPM7, the phosphotransferase-inactive TRPM7 mutant, was unresponsive to aldosterone. Therefore, chronic aldosterone treatment increases the plasma membrane expression of TRPM7, which is associated with an increase of TRPM7 current. This process occurs via an MR-dependent, genomic signaling cascade involving SGK1 and a functioning TRPM7 α-kinase domain. We suggest that this mechanism may be of general relevance when interpreting the effects of aldosterone because the MR receptor is found in multiple tissues, and TRPM7 and SGK1 are ubiquitously expressed. PMID:27466368

Mechanism and pharmacological rescue of berberine-induced hERG channel deficiency

PubMed Central

Yan, Meng; Zhang, Kaiping; Shi, Yanhui; Feng, Lifang; Lv, Lin; Li, Baoxin

2015-01-01

Berberine (BBR), an isoquinoline alkaloid mainly isolated from plants of Berberidaceae family, is extensively used to treat gastrointestinal infections in clinics. It has been reported that BBR can block human ether-a-go-go-related gene (hERG) potassium channel and inhibit its membrane expression. The hERG channel plays crucial role in cardiac repolarization and is the target of diverse proarrhythmic drugs. Dysfunction of hERG channel can cause long QT syndrome. However, the regulatory mechanisms of BBR effects on hERG at cell membrane level remain unknown. This study was designed to investigate in detail how BBR decreased hERG expression on cell surface and further explore its pharmacological rescue strategies. In this study, BBR decreases caveolin-1 expression in a concentration-dependent manner in human embryonic kidney 293 (HEK293) cells stably expressing hERG channel. Knocking down the basal expression of caveolin-1 alleviates BBR-induced hERG reduction. In addition, we found that aromatic tyrosine (Tyr652) and phenylalanine (Phe656) in S6 domain mediate the long-term effect of BBR on hERG by using mutation techniques. Considering both our previous and present work, we propose that BBR reduces hERG membrane stability with multiple mechanisms. Furthermore, we found that fexofenadine and resveratrol shorten action potential duration prolongated by BBR, thus having the potential effects of alleviating the cardiotoxicity of BBR. PMID:26543354

Extracellular matrix components expression in human pluripotent stem cell-derived retinal organoids recapitulates retinogenesis in vivo and reveals an important role for IMPG1 and CD44 in the development of photoreceptors and interphotoreceptor matrix.

PubMed

Felemban, Majed; Dorgau, Birthe; Hunt, Nicola Claire; Hallam, Dean; Zerti, Darin; Bauer, Roman; Ding, Yuchun; Collin, Joseph; Steel, David; Krasnogor, Natalio; Al-Aama, Jumana; Lindsay, Susan; Mellough, Carla; Lako, Majlinda

2018-05-17

The extracellular matrix (ECM) plays an important role in numerous processes including cellular proliferation, differentiation, migration, maturation, adhesion guidance and axonal growth. To date, there has been no detailed analysis of the ECM distribution during retinal ontogenesis in humans and the functional importance of many ECM components is poorly understood. In this study, the expression of key ECM components in adult mouse and monkey retina, developing and adult human retina and retinal organoids derived from human pluripotent stem cells was studied. Our data indicate that basement membrane ECMs (Fibronectin and Collagen IV) were expressed in Bruch's membrane and the inner limiting membrane of the developing human retina, whilst the hyalectins (Versican and Brevican), cluster of differentiation 44 (CD44), photoreceptor-specific ECMs Interphotoreceptor Matrix Proteoglycan 1 (IMPG1) and Interphotoreceptor Matrix Proteoglycan 2 (IMPG2) were detected in the developing interphotoreceptor matrix (IPM). The expression of IMPG1, Versican and Brevican in the developing IPM was conserved between human developing retina and human pluripotent stem cell-derived retinal organoids. Blocking the action of CD44 and IMPG1 in pluripotent stem cell derived retinal organoids affected the development of photoreceptors, their inner/outer segments and connecting cilia and disrupted IPM formation, with IMPG1 having an earlier and more significant impact. Together, our data suggest an important role for IMPG1 and CD44 in the development of photoreceptors and IPM formation during human retinogenesis. The expression and the role of many extracellular matrix (ECM) components during human retinal development is not fully understood. In this study, expression of key ECM components (Collagen IV, Fibronectin, Brevican, Versican, IMPG1 and IMPG2) was investigated during human retinal ontogenesis. Collagen IV and Fibronectin were expressed in Bruch's membrane; whereas Brevican, Versican, IMPG1 & IMPG2 in the developing interphotoreceptor matrix (IPM). Retinal organoids were successfully generated from pluripotent stem cells. The expression of ECM components was examined in the retinal organoids and found to recapitulate human retinal development in vivo. Using functional blocking experiments, we were able to highlight an important role for IMPG1 and CD44 in the development of photoreceptors and IPM formation. Copyright © 2018 Acta Materialia Inc. All rights reserved.

Correlated alterations in prostate basal cell layer and basement membrane

PubMed Central

Liu, Aijun; Wei, Lixin; Gardner, William A.; Deng, Chu-Xia; Man, Yan-Gao

2009-01-01

Our recent studies revealed that focal basal cell layer disruption (FBCLD) induced auto-immunoreactions represented a contributing factor for human prostate tumor progression and invasion. As the basement membrane surrounds and attaches to the basal cell layer, our current study assessed whether FBCLD would impact the physical integrity of the associated basement membrane. Paraffin sections from 25-human prostate tumors were subjected to double immunohistochemistry to simultaneously elucidate the basal cell layer and the basement membrane with corresponding biomarkers. The physical integrity of the basement membrane overlying FBCLD was examined to determine the extent of correlated alterations. Of a total of 89 FBCLD encountered, 76 (85 %) showed correlated alterations in the overlying basement membrane, which included distinct focal disruptions or fragmentations. In the remaining 13 (15%) FBCLD, the overlying basement membrane showed significant attenuation or reduction of the immunostaining intensity. The basement membrane in all or nearly all ducts or acini with p63 positive basal cells was substantially thicker and more uniform than that in ducts or acini without p63 positive basal cells, and also, a vast majority of the focal disruptions occurred near basal cells that lack p63 expression. These findings suggest that focal disruptions in the basal cell layer and alterations in the basement membrane are correlated events and that the physical and functional status of the basal cells could significantly impact the physical integrity of the overlying basement membrane. As the degradation of both the basal cell layer and the basement membrane is a pre-requisite for prostate tumor invasion or progression, ducts or acini with focally disrupted basal cell layer and basement membrane are likely at greater risk to develop invasive lesions. Thus, further elucidation of the specific molecules and mechanism associated with these events may lead to the development of a more effective alternative for repeat biopsy to monitor tumor progression and invasion. PMID:19343113

Petit-High Pressure Carbon Dioxide stress increases synthesis of S-Adenosylmethionine and phosphatidylcholine in yeast Saccharomyces cerevisiae.

PubMed

Niu, Liyuan; Nomura, Kazuki; Iwahashi, Hitoshi; Matsuoka, Hiroyuki; Kawachi, Satoshi; Suzuki, Yoshihisa; Tamura, Katsuhiro

2017-12-01

Petit-High Pressure Carbon Dioxide (p-HPCD) is a promising nonthermal technology for foods pasteurization. Cluster analysis of gene expression profiles of Saccharomyces cerevisiae exposed to various stresses exhibited that gene expression profile for p-HPCD stress (0.5MPa, 25°C) was grouped into a cluster including profiles for Sodium Dodecyl Sulfate and Roundup herbicide. Both are detergents that can disorder membrane structurally and functionally, which suggests that cell membrane may be a target of p-HPCD stress to cause cell growth inhibition. Through metabolomic analysis, amount of S-Adenosylmethionine (AdoMet) that is used as methyl donor to participate in phosphatidylcholine synthesis via phosphatidylethanolamine (PE) methylation pathway, was increased after p-HPCD treatment for 2h. The key gene OPI3 encoding phospholipid methyltransferase that catalyzes the last two steps in PE methylation pathway was confirmed significantly induced by RT-PCR. Transcriptional expression of genes (MET13, MET16, MET10, MET17, MET6 and SAM2) related to AdoMet biosynthesis was also significantly induced. Choline as the PC precursor and ethanolamine as PE precursor in Kennedy pathway were also found increased under p-HPCD condition. We also found that amounts of most of amino acids involving protein synthesis were found decreased after p-HPCD treatment for 2h. Moreover, morphological changes on cell surface were observed by scanning electron microscope. In conclusion, the effects of p-HPCD stress on cell membrane appear to be a very likely cause of yeast growth inhibition and the enhancement of PC synthesis could contribute to maintain optimum structure and functions of cell membrane and improve cell resistance to inactivation. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid Steroid Hormone Actions Initiated at the Cell Surface and the Receptors that Mediate Them with an Emphasis on Recent Progress in Fish Models

PubMed Central

Thomas, Peter

2011-01-01

In addition to the classic genomic mechanism of steroid action mediated by activation of intracellular nuclear receptors, there is now extensive evidence that steroids also activate receptors on the cell surface to initiate rapid intracellular signaling and biological responses that are often nongenomic. Recent progress in our understanding of rapid, cell surface-initiated actions of estrogens, progestins, androgens and corticosteroids and the identities of the membrane receptors that act as their intermediaries is briefly reviewed with a special emphasis on studies in teleost fish. Two recently discovered novel proteins with seven-transmembrane domains, G protein-coupled receptor 30 (GPR30), and membrane progestin receptors (mPRs) have the ligand binding and signaling characteristics of estrogen and progestin membrane receptors, respectively, but their functional significance is disputed by some researchers. GPR30 is expressed on the cell surface of fish oocytes and mediates estrogen inhibition of oocyte maturation. mPRα is also expressed on the oocyte cell surface and is the intermediary in progestin induction of oocyte maturation in fish. Recent results suggest there is cross-talk between these two hormonal pathways and that there is reciprocal down-regulation of GPR30 and mPRα expression by estrogens and progestins at different phases of oocyte development to regulate the onset of oocyte maturation. There is also evidence in fish that mPRs are involved in progestin induction of sperm hypermotility and anti-apoptotic actions in ovarian follicle cells. Nonclassical androgen and corticosteroid actions have also been described in fish models but the membrane receptors mediating these actions have not been identified. PMID:22154643

Membrane-bound (MUC1) and secretory (MUC2, MUC3, and MUC4) mucin gene expression in human lung cancer.

PubMed

Nguyen, P L; Niehans, G A; Cherwitz, D L; Kim, Y S; Ho, S B

1996-01-01

Abnormalities of mucin-type glycoproteins have been described in lung cancers, but their molecular basis is unknown. In this study, mucin-core-peptide-specific antibodies and cDNA probes were used to determine the relative expression of mucin genes corresponding to one membrane-bound mucin (MUC1), two intestinal mucins (MUC2 and MUC3), and one tracheobronchial mucin (MUC4) in normal (nonneoplastic) lung, and in lung neoplasms. Normal lung tissues exhibited a distinct pattern of mucin gene expression, with high levels of MUC1 and MUC4 mRNA and low to absent levels of MUC2 and MUC3 mucin immunoreactivity and mRNA. In contrast, lung adenocarcinomas, especially well-differentiated cancers, exhibited increased MUC1, MUC3, and MUC4 mRNA levels. Lung squamous-cell, adenosquamous, and large-cell carcinomas were characterized by increased levels of MUC4 mucin only. We conclude that the expression of one membrane-bound and several secretory-type mucins is independently regulated and markedly altered in lung neoplasms. The frequent occurrence of increased MUC4 transcripts in a variety of non-small-cell lung cancers indicates the potential importance of this type of mucin in lung cancer biology.

Arabidopsis tetraspanins are confined to discrete expression domains and cell types in reproductive tissues and form homo-and heterodimers when expressed in yeast

USDA-ARS?s Scientific Manuscript database

Tetraspanins are evolutionary conserved transmembrane proteins present in all multicellular organisms. In animals, they are known to act as central organizers of membrane complexes and thought to facilitate diverse biological processes, such as cell proliferation, movement, adhesion, and fusion. The...

Expressions of apoptosis-regulating factors in bovine retained placenta.

PubMed

Kamemori, Y; Wakamiya, K; Nishimura, R; Hosaka, Y; Ohtani, S; Okuda, K

2011-01-01

The aim of the present study was to evaluate the relationship between the retention of fetal membranes (RFM) and apoptosis of the cells in fetal membranes. The present study investigated mRNA and protein expressions of apoptosis-regulating factors: FAS, cellular FLICE-like inhibiting protein (cFLIP), BAX, BCL2, caspase-8 (CASP8), and CASP3 in fetal membranes. Placentomes were manually collected from the uterus immediately after parturition and classified into two groups (RFM; n = 8 and non-RFM; n = 8) according to whether placental membranes were expelled or not within 12 h after delivery. FAS mRNA expression in maternal placental tissue was less in RFM cows than in non-RFM cows (P < 0.05). cFLIP mRNA expression in maternal and fetal placental tissue was greater in RFM cows than in non-RFM cows (P < 0.05). CASP3 mRNA expression in maternal placental tissue was greater in RFM cows than in non-RFM cows (P < 0.05). However, the protein expressions of FAS, cFLIP and cleaved CASP3 were not significantly different between the two groups. mRNA and protein expressions of BAX, BCL2 and CASP8 were also not significantly different between the two groups. In the immunohistochemical study, single-stranded DNA, which appears specifically in the apoptotic cells, was mainly found in the maternal placenta of non-RFM cows. Together these results suggest that RFM occurs at least in part due to a dysfunctional apoptotic process caused by the inhibition of FAS expression in the maternal placenta, and the increase of cFLIP expression in the maternal and fetal placenta. Copyright © 2010 Elsevier Ltd. All rights reserved.

Relation of follicular dendritic reticulum cells to Reed-Sternberg cells of Hodgkin's disease with emphasis on the expression of CD21 antigen.

PubMed Central

Delsol, G.; Meggetto, F.; Brousset, P.; Cohen-Knafo, E.; al Saati, T.; Rochaix, P.; Gorguet, B.; Rubin, B.; Voigt, J. J.; Chittal, S.

1993-01-01

Based on observations of 66 cases, in which tissues were specially processed to optimize the simultaneous preservation of cell membrane antigens and morphology, we provide evidence in favor of a relationship between follicular dendritic reticulum cells (FDRC) and Reed-Sternberg (RS) cells of Hodgkin's disease (HD) other than the lymphocyte predominance subtype. RS cells were intimately related to the FDRC network (75% of cases), and the expression of CD21 antigen was frequent (41% of cases). Exclusive expression of CD21 antigen was found in 11 cases of HD, while the expression of other B-cell-associated markers (CD19, CD20, CD22) was both variable and inconsistent. The expression of T-cell antigens (CD3, CD4, CD8) was rare. Null phenotype of RS cells was observed in 27 of 66 cases (41%). Epstein-Barr virus (EBV) nucleic acids were found in 34 of 66 (51.5%) cases. Double labeling techniques showed the presence of EBV-positive RS cells within the FDRC network. A non-B-cell origin of RS cells was supported by the differential expression of EBV latent antigens in HD (latent membrane protein+, EB nuclear antigen 2-), which is unusual in EBV-driven lymphoblastoid cell lines and EBV-positive B-cell lymphomas. FDRC and RS cells are known to share morphological traits (binucleated cells), and both cell types possess Fc receptor for IgG. The hypothesis is further backed by the findings of CD15 antigen expression by occasional RS-like dysplastic FDRC in Castleman's disease (five cases), which is characterized by hyperplasia of FDRC. Whether FDRC might be the only cells involved in the conversion to RS cells by the loss or gain of antigens remains to be determined. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:7685151

The canonical WNT2 pathway and FSH interact to regulate gap junction assembly in mouse granulosa cells.

PubMed

Wang, Hong-Xing; Gillio-Meina, Carolina; Chen, Shuli; Gong, Xiang-Qun; Li, Tony Y; Bai, Donglin; Kidder, Gerald M

2013-08-01

WNTs are extracellular signaling molecules that exert their actions through receptors of the frizzled (FZD) family. Previous work indicated that WNT2 regulates cell proliferation in mouse granulosa cells acting through CTNNB1 (beta-catenin), a key component in canonical WNT signaling. In other cells, WNT signaling has been shown to regulate expression of connexin43 (CX43), a gap junction protein, as well as gap junction assembly. Since previous work demonstrated that CX43 is also essential in ovarian follicle development, the objective of this study was to determine if WNT2 regulates CX43 expression and/or gap-junctional intercellular communication (GJIC) in granulosa cells. WNT2 knockdown via siRNA markedly reduced CX43 expression and GJIC. CX43 expression, the extent of CX43-containing gap junction membrane, and GJIC were also reduced by CTNNB1 transient knockdown. CTNNB1 is mainly localized to the membranes between granulosa cells but disappeared from this location after WNT2 knockdown. Furthermore, CTNNB1 knockdown interfered with the ability of follicle-stimulating hormone (FSH) to promote the mobilization of CX43 into gap junctions. We propose that the WNT2/CTNNB1 pathway regulates CX43 expression and GJIC in granulosa cells by modulating CTNNB1 stability and localization in adherens junctions, and that this is essential for FSH stimulation of GJIC.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubo, Yoshinao; Yoshii, Hiroaki; Kamiyama, Haruka

Ezrin, radixin, and moesin (ERM) proteins supply functional linkage between integral membrane proteins and cytoskeleton in mammalian cells to regulate membrane protein dynamisms and cytoskeleton rearrangement. To assess potential role of the ERM proteins in HIV-1 lifecycle, we examined if suppression of ERM function in human cells expressing HIV-1 infection receptors influences HIV-1 envelope (Env)-mediated HIV-1-vector transduction and cell-cell fusion. Expression of an ezrin dominant negative mutant or knockdown of ezrin, radixin, or moesin with siRNA uniformly decreased transduction titers of HIV-1 vectors having X4-tropic Env. In contrast, transduction titers of R5-tropic Env HIV-1 vectors were decreased only by radixinmore » knockdown: ezrin knockdown had no detectable effects and moesin knockdown rather increased transduction titer. Each of the ERM suppressions had no detectable effects on cell surface expression of CD4, CCR5, and CXCR4 or VSV-Env-mediated HIV-1 vector transductions. Finally, the individual knockdown of ERM mRNAs uniformly decreased efficiency of cell-cell fusion mediated by X4- or R5-tropic Env and HIV-1 infection receptors. These results suggest that (i) the ERM proteins function as positive regulators of infection by X4-tropic HIV-1, (ii) moesin additionally functions as a negative regulator of R5-tropic HIV-1 virus infection at the early step(s) after the membrane fusion, and (iii) receptor protein dynamisms are regulated differently in R5- and X4-tropic HIV-1 infections.« less

Physalis floridana Cell Number Regulator1 encodes a cell membrane-anchored modulator of cell cycle and negatively controls fruit size

PubMed Central

Li, Zhichao; He, Chaoying

2015-01-01

Physalis species show a significant variation in berry size; however, the underlying molecular basis is unknown. In this work, we showed that cell division difference in the ovaries might contribute to the ultimate berry size variation within Physalis species, and that mRNA abundance of Physalis floridana Cell Number Regulator1 (PfCNR1), the putative orthologue of the tomato fruit weight 2.2 (FW2.2), was negatively correlated with cell division in the ovaries. Moreover, heterochronic expression variation of the PfCNR1 genes in the ovaries concomitantly correlated with berry weight variation within Physalis species. In transgenic Physalis, multiple organ sizes could be negatively controlled by altering PfCNR1 levels, and cell division instead of cell expansion was primarily affected. PfCNR1 was shown to be anchored in the plasma membrane and to interact with PfAG2 (an AGAMOUS-like protein determining ovary identity). The expression of PfCYCD2;1, a putative orthologue of the mitosis-specific gene CyclinD2;1 in the cell cycle was negatively correlated with the PfCNR1 mRNA levels. PfAG2 was found to selectively bind to the CArG-box in the PfCYCD2;1 promoter and to repress PfCYCD2;1 expression, thus suggesting a PfAG2-mediated pathway for PfCNR1 to regulate cell division. The interaction of PfCNR1 with PfAG2 enhanced the repression of PfCYCD2;1 expression. The nuclear import of PfAG2 was essential in the proposed pathway. Our data provide new insights into the developmental pathways of a cell membrane-anchored protein that modulates cell division and governs organ size determination. This study also sheds light on the link between organ identity and organ growth in plants. PMID:25305759

Use of quantitative optical imaging to examine the role of cholesterol-rich lipid raft microdomains in the migration of breast cancer cells

NASA Astrophysics Data System (ADS)

You, Minghai; Chen, Jianling; Wang, Shaobing; Dong, Shiqing; Wang, Yuhua; Xie, Shusen; Wang, Zhengchao; Yang, Hongqin

2018-04-01

Lipid rafts have been extensively studied and shown to be involved in many cancers, including breast cancer. However, the exact role of lipid rafts in the migration of breast cancer cells remains unclear. This study was designed to examine lipid rafts (cholesterol) in the plasma membrane of breast cancer cells (MDA-MB-231 and MCF-7) and normal breast epithelial cells (MCF-10A) through generalized polarization values, and further investigate the role of cholesterol-rich lipid rafts in the migration of breast cancer cells. The results showed that the plasma membrane in breast cancer cells was more orderly than that in normal epithelial cells; this was correlated with expression changes of matrix metallopeptidase 9 (MMP-9) and urokinase-type plasminogen activator receptor (uPAR), the markers of cancer cell migration. Moreover, the breast cancer cells were more sensitive to the reagent that induced cholesterol depletion than the normal breast epithelial cells, while the capacity of cancer cells to migrate decreased significantly according to changes in MMP-9 and uPAR expression. To our best knowledge, this is the first demonstration of the relationship between cholesterol-rich lipid rafts and the migration of breast cancer cells; it could be useful for the prevention of breast cancer and early treatment through reduction of the level of cholesterol in the plasma membrane of the cells.

Extracellular localization of catalase is associated with the transformed state of malignant cells.

PubMed

Böhm, Britta; Heinzelmann, Sonja; Motz, Manfred; Bauer, Georg

2015-12-01

Oncogenic transformation is dependent on activated membrane-associated NADPH oxidase (NOX). However, the resultant extracellular superoxide anions are also driving the NO/peroxynitrite and the HOCl pathway, which eliminates NOX-expressing transformed cells through selective apoptosis induction. Tumor progression is dependent on dominant interference with intercellular apoptosis-inducing ROS signaling through membrane-associated catalase, which decomposes H2O2 and peroxynitrite and oxidizes NO. Particularly, the decomposition of extracellular peroxynitrite strictly requires membrane-associated catalase. We utilized small interfering RNA (siRNA)-mediated knockdown of catalase and neutralizing antibodies directed against the enzyme in combination with challenging H2O2 or peroxynitrite to determine activity and localization of catalase in cells from three distinct steps of multistage oncogenesis. Nontransformed cells did not generate extracellular superoxide anions and only showed intracellular catalase activity. Transformed cells showed superoxide anion-dependent intercellular apoptosis-inducing ROS signaling in the presence of suboptimal catalase activity in their membrane. Tumor cells exhibited tight control of intercellular apoptosis-inducing ROS signaling through a high local concentration of membrane-associated catalase. These data demonstrate that translocation of catalase to the outside of the cell membrane is already associated with the transformation step. A strong local increase in the concentration of membrane-associated catalase is achieved during tumor progression and is controlled by tumor cell-derived H2O2 and by transglutaminase.

Antioxidative Dietary Compounds Modulate Gene Expression Associated with Apoptosis, DNA Repair, Inhibition of Cell Proliferation and Migration

PubMed Central

Wang, Likui; Gao, Shijuan; Jiang, Wei; Luo, Cheng; Xu, Maonian; Bohlin, Lars; Rosendahl, Markus; Huang, Wenlin

2014-01-01

Many dietary compounds are known to have health benefits owing to their antioxidative and anti-inflammatory properties. To determine the molecular mechanism of these food-derived compounds, we analyzed their effect on various genes related to cell apoptosis, DNA damage and repair, oxidation and inflammation using in vitro cell culture assays. This review further tests the hypothesis proposed previously that downstream products of COX-2 (cyclooxygenase-2) called electrophilic oxo-derivatives induce antioxidant responsive elements (ARE), which leads to cell proliferation under antioxidative conditions. Our findings support this hypothesis and show that cell proliferation was inhibited when COX-2 was down-regulated by polyphenols and polysaccharides. Flattened macrophage morphology was also observed following the induction of cytokine production by polysaccharides extracted from viili, a traditional Nordic fermented dairy product. Coix lacryma-jobi (coix) polysaccharides were found to reduce mitochondrial membrane potential and induce caspase-3- and 9-mediated apoptosis. In contrast, polyphenols from blueberries were involved in the ultraviolet-activated p53/Gadd45/MDM2 DNA repair system by restoring the cell membrane potential. Inhibition of hypoxia-inducible factor-1 by saponin extracts of ginsenoside (Ginsen) and Gynostemma and inhibition of S100A4 by coix polysaccharides inhibited cancer cell migration and invasion. These observations suggest that antioxidants and changes in cell membrane potential are the major driving forces that transfer signals through the cell membrane into the cytosol and nucleus, triggering gene expression, changes in cell proliferation and the induction of apoptosis or DNA repair. PMID:25226533

Melatonin inhibits nucleus pulposus (NP) cell proliferation and extracellular matrix (ECM) remodeling via the melatonin membrane receptors mediated PI3K-Akt pathway.

PubMed

Li, Zheng; Li, Xingye; Chen, Chong; Chan, Matthew T V; Wu, William Ka Kei; Shen, Jianxiong

2017-10-01

Pinealectomy in vertebrates accelerated intervertebral disk degeneration (IDD). However, the potential mechanisms, particularly melatonin's role, are still to be clarified. In this study, for first time, melatonin membrane receptors of MT1 and MT2 were found to be present in the human intervertebral disk tissues and nucleus pulposus (NP) cells, respectively. Melatonin treatment significantly inhibited NP cell proliferation in dose-dependent manner. Accordingly, melatonin down-regulated gene expression of cyclin D1, PCNA, matrix metallopeptidase-3, and matrix metallopeptidase-9 and upregulated gene expression of collagen type II alpha 1 chain and aggrecan in NP cells. These effects of melatonin were blocked by luzindole, a nonspecific melatonin membrane receptor antagonist. Signaling pathway analysis indicated that in the intervertebral disk tissues and NP cells, melatonin acted on MT1/2 and subsequently reduced phosphorylation of phosphoinositide 3-kinase p85 regulatory subunit, phosphoinositide-dependent kinase-1, and Akt. The results indicate that melatonin is a crucial regulator of NP cell function and plays a vital role in prevention of IDD. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

GREG cells, a dysferlin-deficient myogenic mouse cell line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humphrey, Glen W.; Mekhedov, Elena; Blank, Paul S.

2012-01-15

The dysferlinopathies (e.g. LGMD2b, Myoshi myopathy) are progressive, adult-onset muscle wasting syndromes caused by mutations in the gene coding for dysferlin. Dysferlin is a large ({approx} 200 kDa) membrane-anchored protein, required for maintenance of plasmalemmal integrity in muscle fibers. To facilitate analysis of dysferlin function in muscle cells, we have established a dysferlin-deficient myogenic cell line (GREG cells) from the A/J mouse, a genetic model for dysferlinopathy. GREG cells have no detectable dysferlin expression, but proliferate normally in growth medium and fuse into functional myotubes in differentiation medium. GREG myotubes exhibit deficiencies in plasma membrane repair, as measured by lasermore » wounding in the presence of FM1-43 dye. Under the wounding conditions used, the majority ({approx} 66%) of GREG myotubes lack membrane repair capacity, while no membrane repair deficiency was observed in dysferlin-normal C2C12 myotubes, assayed under the same conditions. We discuss the possibility that the observed heterogeneity in membrane resealing represents genetic compensation for dysferlin deficiency.« less

Controlling cytoplasmic c-Fos controls tumor growth in the peripheral and central nervous system.

PubMed

Gil, Germán A; Silvestre, David C; Tomasini, Nicolás; Bussolino, Daniela F; Caputto, Beatriz L

2012-06-01

Some 20 years ago c-Fos was identified as a member of the AP-1 family of inducible transcription factors (Angel and Karin in Biochim Biophys Acta 1072:129-157, 1991). More recently, an additional activity was described for this protein: it associates to the endoplasmic reticulum and activates the biosynthesis of phospholipids (Bussolino et al. in FASEB J 15:556-558, 2001), (Gil et al. in Mol Biol Cell 15:1881-1894, 2004), the quantitatively most important components of cellular membranes. This latter activity of c-Fos determines the rate of membrane genesis and consequently of growth in differentiating PC12 cells (Gil et al. in Mol Biol Cell 15:1881-1894, 2004). In addition, it has been shown that c-Fos is over-expressed both in PNS and CNS tumors (Silvestre et al. in PLoS One 5(3):e9544, 2010). Herein, it is shown that c-Fos-activated phospholipid synthesis is required to support membrane genesis during the exacerbated growth characteristic of brain tumor cells. Specifically blocking c-Fos-activated phospholipid synthesis significantly reduces proliferation of tumor cells in culture. Blocking c-Fos expression also prevents tumor progression in mice intra-cranially xeno-grafted human brain tumor cells. In NPcis mice, an animal model of the human disease Neurofibromatosis Type I (Cichowski and Jacks in Cell 104:593-604, 2001), animals spontaneously develop tumors of the PNS and the CNS, provided they express c-Fos (Silvestre et al. in PLoS One 5(3):e9544, 2010). Treatment of PNS tumors with an antisense oligonucleotide that specifically blocks c-Fos expression also blocks tumor growth in vivo. These results disclose cytoplasmic c-Fos as a new target for effectively controlling brain tumor growth.

In situ cell surface proteomics reveals differentially expressed membrane proteins in retinal pigment epithelial cells during autoimmune uveitis.

PubMed

Uhl, P B; Szober, C M; Amann, B; Alge-Priglinger, C; Ueffing, M; Hauck, S M; Deeg, C A

2014-09-23

Retinal pigment epithelium (RPE) builds the outer blood-retinal barrier of the eye and plays an important role in pathogenesis of the sight threatening disease equine recurrent uveitis (ERU). ERU is a spontaneous autoimmune mediated inflammatory disease characterised by the breakdown of the outer blood-retinal barrier and an influx of autoaggressive T-cells into the inner eye. Therefore, identification of molecular mechanisms contributing to changed function of blood-retinal barrier in ERU is important for the understanding of pathophysiology. Cell surface proteins of RPE collected from healthy horses and horses with ERU were captured by in situ biotinylation and analysed with high resolution mass spectrometry coupled to liquid chromatography (LC-MS/MS) to identify differentially expressed proteins. With label free differential proteomics, a total of 27 differently expressed cell surface proteins in diseased RPE could be detected. Significant down-regulation of three very interesting proteins, synaptotagmin 1, basigin and collectrin was verified and further characterised. We applied an innovative and successful method to detect changes in the plasma cell surface proteome of RPE cells in a spontaneous inflammatory eye disease, serving as a valuable model for human autoimmune uveitis. We were able to identify 27 differentially expressed plasma cell membrane proteins, including synaptotagmin 1, basigin and collectrin, which play important roles in cell adhesion, transport and cell communication. Copyright © 2014 Elsevier B.V. All rights reserved.

Role of Bruton's tyrosine kinase inhibitors in HIV-1-infected cells.

PubMed

Guendel, Irene; Iordanskiy, Sergey; Sampey, Gavin C; Van Duyne, Rachel; Calvert, Valerie; Petricoin, Emanuel; Saifuddin, Mohammed; Kehn-Hall, Kylene; Kashanchi, Fatah

2015-06-01

Many cellular cofactors have been documented to be critical for various stages of viral replication. Using high-throughput proteomic assays, we have previously identified Bruton's tyrosine kinase (BTK) as a host protein that was uniquely upregulated in the plasma membrane of human immunodeficiency virus (HIV-1)-infected T cells. Here, we have further characterized the BTK expression in HIV-1 infection and show that this cellular factor is specifically expressed in infected myeloid cells. Significant upregulation of the phosphorylated form of BTK was observed in infected cells. Using size exclusion chromatography, we found BTK to be virtually absent in the uninfected U937 cells; however, new BTK protein complexes were identified and distributed in both high molecular weight (∼600 kDa) and a small molecular weight complex (∼60-120 kDa) in the infected U1 cells. BTK levels were highest in cells either chronically expressing virus or induced/infected myeloid cells and that BTK translocated to the membrane following induction of the infected cells. BTK knockdown in HIV-1-infected cells using small interfering RNA (siRNA) resulted in selective death of infected, but not uninfected, cells. Using BTK-specific antibody and small-molecule inhibitors including LFM-A13 and a FDA-approved compound, ibrutinib (PCI-32765), we have found that HIV-1-infected cells are sensitive to apoptotic cell death and result in a decrease in virus production. Overall, our data suggests that HIV-1-infected cells are sensitive to treatments targeting BTK expressed in infected cells.

Role of Bruton’s Tyrosine Kinase inhibitors in HIV-1 infected cells

PubMed Central

Guendel, Irene; Iordanskiy, Sergey; Sampey, Gavin C; Van Duyne, Rachel; Calvert, Valerie; Petricoin, Emanuel; Saifuddin, Mohammed; Kehn-Hall, Kylene; Kashanchi, Fatah

2015-01-01

Many cellular cofactors have been documented to be critical for various stages of viral replication. Using high throughput proteomic assays, we have previously identified Bruton’s tyrosine kinase (BTK) as a host protein that was uniquely up-regulated in the plasma membrane of HIV-1 infected T-cells. Here, we have further characterized the BTK expression in HIV-1 infection and show that this cellular factor is specifically expressed in infected myeloid cells. Significant up-regulation of the phosphorylated form of BTK was observed in infected cells. Using size exclusion chromatography, we found BTK to be virtually absent in the uninfected U937 cells, however new BTK protein complexes were identified and distributed in both high molecular weight (~600 kDa) and a small molecular weight complex (~60–120 kDa) in the infected U1 cells. BTK levels were highest in cells either chronically expressing virus or induced/infected myeloid cells and that BTK translocated to the membrane following induction of the infected cells. BTK knockdown in HIV-1 infected cells using siRNA resulted in selective death of infected, but not uninfected, cells. Using BTK specific antibody and small molecule inhibitors including LFM-A13 and a FDA approved compound, Ibrutinib (PCI – 32765), we have found that HIV-1 infected cells are sensitive to apoptotic cell death and result in a decrease in virus production. Overall, our data suggests that HIV-1 infected cells are sensitive to treatments targeting BTK expressed in infected cells. PMID:25672887

Multilayer Membranes of Glycosaminoglycans and Collagen I Biomaterials Modulate the Function and Microvesicle Release of Endothelial Progenitor Cells.

PubMed

Dai, Bingyan; Pan, Qunwen; Li, Zhanghua; Zhao, Mingyan; Liao, Xiaorong; Wu, Keng; Ma, Xiaotang

2016-01-01

Multilayer composite membrane of biomaterials can increase the function of adipose stem cells or osteoprogenitor cells. Recent evidence indicates endothelial progenitor cells (EPCs) and EPCs released microvesicles (MVs) play important roles in angiogenesis and vascular repair. Here, we investigated the effects of biomaterial multilayer membranes of hyaluronic acid (HA) or chondroitin sulfate (CS) and Collagen I (Col I) on the functions and MVs release of EPCs. Layer-by-layer (LBL) technology was applied to construct the multilayer composite membranes. Four types of the membranes constructed by adsorbing either HA or CS and Col I alternatively with different top layers were studied. The results showed that all four types of multilayer composite membranes could promote EPCs proliferation and migration and inhibit cell senility, apoptosis, and the expression of activated caspase-3. Interestingly, these biomaterials increased the release and the miR-126 level of EPCs-MVs. Moreover, the CS-Col I membrane with CS on the top layer showed the most effects on promoting EPCs proliferation, EPCs-MV release, and miR-126 level in EPCs-MVs. In conclusion, HA/CS and Collagen I composed multilayer composite membranes can promote EPCs functions and release of miR-126 riched EPCs-MVs, which provides a novel strategy for tissue repair treatment.

Remodeling of the Host Cell Plasma Membrane by HIV-1 Nef and Vpu: A Strategy to Ensure Viral Fitness and Persistence.

PubMed

Sugden, Scott M; Bego, Mariana G; Pham, Tram N Q; Cohen, Éric A

2016-03-03

The plasma membrane protects the cell from its surroundings and regulates cellular communication, homing, and metabolism. Not surprisingly, the composition of this membrane is highly controlled through the vesicular trafficking of proteins to and from the cell surface. As intracellular pathogens, most viruses exploit the host plasma membrane to promote viral replication while avoiding immune detection. This is particularly true for the enveloped human immunodeficiency virus (HIV), which assembles and obtains its lipid shell directly at the plasma membrane. HIV-1 encodes two proteins, negative factor (Nef) and viral protein U (Vpu), which function primarily by altering the quantity and localization of cell surface molecules to increase virus fitness despite host antiviral immune responses. These proteins are expressed at different stages in the HIV-1 life cycle and employ a variety of mechanisms to target both unique and redundant surface proteins, including the viral receptor CD4, host restriction factors, immunoreceptors, homing molecules, tetraspanins and membrane transporters. In this review, we discuss recent progress in the study of the Nef and Vpu targeting of host membrane proteins with an emphasis on how remodeling of the cell membrane allows HIV-1 to avoid host antiviral immune responses leading to the establishment of systemic and persistent infection.

Fendiline Inhibits K-Ras Plasma Membrane Localization and Blocks K-Ras Signal Transmission

PubMed Central

van der Hoeven, Dharini; Cho, Kwang-jin; Ma, Xiaoping; Chigurupati, Sravanthi; Parton, Robert G.

2013-01-01

Ras proteins regulate signaling pathways important for cell growth, differentiation, and survival. Oncogenic mutant Ras proteins are commonly expressed in human tumors, with mutations of the K-Ras isoform being most prevalent. To be active, K-Ras must undergo posttranslational processing and associate with the plasma membrane. We therefore devised a high-content screening assay to search for inhibitors of K-Ras plasma membrane association. Using this assay, we identified fendiline, an L-type calcium channel blocker, as a specific inhibitor of K-Ras plasma membrane targeting with no detectable effect on the localization of H- and N-Ras. Other classes of L-type calcium channel blockers did not mislocalize K-Ras, suggesting a mechanism that is unrelated to calcium channel blockade. Fendiline did not inhibit K-Ras posttranslational processing but significantly reduced nanoclustering of K-Ras and redistributed K-Ras from the plasma membrane to the endoplasmic reticulum (ER), Golgi apparatus, endosomes, and cytosol. Fendiline significantly inhibited signaling downstream of constitutively active K-Ras and endogenous K-Ras signaling in cells transformed by oncogenic H-Ras. Consistent with these effects, fendiline blocked the proliferation of pancreatic, colon, lung, and endometrial cancer cell lines expressing oncogenic mutant K-Ras. Taken together, these results suggest that inhibitors of K-Ras plasma membrane localization may have utility as novel K-Ras-specific anticancer therapeutics. PMID:23129805

Promotion of human mesenchymal stem cell osteogenesis by PI3-kinase/Akt signaling, and the influence of caveolin-1/cholesterol homeostasis.

PubMed

Baker, Natasha; Sohn, Jihee; Tuan, Rocky S

2015-12-01

Stem cells are considered an important resource for tissue repair and regeneration. Their utilization in regenerative medicine will be aided by mechanistic insight into their responsiveness to external stimuli. It is likely that, similar to all other cells, an initial determinant of stem cell responsiveness to external stimuli is the organization of signaling molecules in cell membrane rafts. The clustering of signaling molecules in these cholesterol-rich membrane microdomains can affect the activity, specificity, cross-talk and amplification of cell signaling. Membrane rafts fall into two broad categories, non-caveolar and caveolar, based on the absence or presence, respectively, of caveolin scaffolding proteins. We have recently demonstrated that caveolin-1 (Cav-1) expression increases during, and knockdown of Cav-1 expression enhances, osteogenic differentiation of human bone marrow derived mesenchymal stem cells (MSCs). The increase in Cav-1 expression observed during osteogenesis is likely a negative feedback mechanism. We hypothesize that focal adhesion signaling pathways such as PI3K/Akt signaling may be negatively regulated by Cav-1 during human MSC osteogenesis. Human bone marrow MSCs were isolated from femoral heads obtained after total hip arthroplasty. MSCs were incubated in standard growth medium alone or induced to osteogenically differentiate by the addition of supplements (β-glycerophosphate, ascorbic acid, dexamethasone, and 1,25-dihydroxyvitamin D3). The activation of and requirement for PI3K/Akt signaling in MSC osteogenesis were assessed by immunoblotting for phosphorylated Akt, and treatment with the PI3K inhibitor LY294002 and Akt siRNA, respectively. The influences of Cav-1 and cholesterol membrane rafts on PI3K/Akt signaling were investigated by treatment with Cav-1 siRNA, methyl-β-cyclodextrin, or cholesterol oxidase, followed by cellular sub-fractionation and/or immunoblotting for phosphorylated Akt. LY294002 and Akt siRNA inhibited MSC osteogenesis. Methyl-β-cyclodextrin, which disrupts all membrane rafts, inhibited osteogenesis. Conversely, Cav-1 siRNA and cholesterol oxidase, which displaces Cav-1 from caveolae, enhanced Akt signaling induced by osteogenic supplements. In control cells, phosphorylated Akt began to accumulate in caveolae after 10 days of osteogenic differentiation. PI3K/Akt signaling is a key pathway required for human MSC osteogenesis, and it is likely that localization of active Akt in non-caveolar and caveolar membrane rafts positively and negatively contributes to osteogenesis, respectively.

The coiled-coil domain of MURC/cavin-4 is involved in membrane trafficking of caveolin-3 in cardiomyocytes.

PubMed

Naito, Daisuke; Ogata, Takehiro; Hamaoka, Tetsuro; Nakanishi, Naohiko; Miyagawa, Kotaro; Maruyama, Naoki; Kasahara, Takeru; Taniguchi, Takuya; Nishi, Masahiro; Matoba, Satoaki; Ueyama, Tomomi

2015-12-15

Muscle-restricted coiled-coil protein (MURC), also referred to as cavin-4, is a member of the cavin family that works cooperatively with caveolins in caveola formation and function. Cavins are cytoplasmic proteins with coiled-coil domains and form heteromeric complexes, which are recruited to caveolae in cells expressing caveolins. Among caveolins, caveolin-3 (Cav3) is exclusively expressed in muscle cells, similar to MURC/cavin-4. In the heart, Cav3 overexpression contributes to cardiac protection, and its deficiency leads to progressive cardiomyopathy. Mutations in the MURC/cavin-4 gene have been identified in patients with dilated cardiomyopathy. In the present study, we show the role of MURC/cavin-4 as a caveolar component in the heart. In H9c2 cells, MURC/cavin-4 was localized at the plasma membrane, whereas a MURC/cavin-4 mutant lacking the coiled-coil domain (ΔCC) was primarily localized to the cytoplasm. ΔCC bound to Cav3 and impaired membrane localization of Cav3 in cardiomyocytes. Additionally, although ΔCC did not alter Cav3 mRNA expression, ΔCC decreased the Cav3 protein level. MURC/cavin-4 and ΔCC similarly induced cardiomyocyte hypertrophy; however, ΔCC showed higher hypertrophy-related fetal gene expression than MURC/cavin-4. ΔCC induced ERK activation in cardiomyocytes. Transgenic mice expressing ΔCC in the heart (ΔCC-Tg mice) showed impaired cardiac function accompanied by cardiomyocyte hypertrophy and marked interstitial fibrosis. Hearts from ΔCC-Tg mice showed a reduction of the Cav3 protein level and activation of ERK. These results suggest that MURC/cavin-4 requires its coiled-coil domain to target the plasma membrane and to stabilize Cav3 at the plasma membrane of cardiomyocytes and that MURC/cavin-4 functions as a crucial caveolar component to regulate cardiac function. Copyright © 2015 the American Physiological Society.

The level of HER2 expression is a predictor of antibody-HER2 trafficking behavior in cancer cells

PubMed Central

Ram, Sripad; Kim, Dongyoung; Ober, Raimund J; Ward, E Sally

2014-01-01

The receptor tyrosine kinase HER2 is known to play a central role in mitogenic signaling, motivating the development of targeted, HER2-specific therapies. However, despite the longstanding use of antibodies to target HER2, controversies remain concerning antibody/HER2 trafficking behavior in cancer cells. Understanding this behavior has direct relevance to the mechanism of action and effective design of such antibodies. In the current study, we analyzed the intracellular dynamics of trastuzumab, a marketed HER2-targeting antibody, in a panel of breast and prostate cancer cell lines that have a wide range of HER2 expression levels. Our results reveal distinct post-endocytic trafficking behavior of antibody-HER2 complexes in cells with different HER2 expression levels. In particular, HER2-overexpressing cells exhibit efficient HER2 recycling and limited reductions in HER2 levels upon antibody treatment, and consequently display a high level of antibody persistence on their plasma membrane. By contrast, in cells with low HER2 expression, trastuzumab treatment results in rapid antibody clearance from the plasma membrane combined with substantial decreases in HER2 levels and undetectable levels of recycling. A cell line with intermediate levels of HER2 expression exhibits both antibody recycling and clearance from the cell surface. Significantly, these analyses demonstrate that HER2 expression levels, rather than cell origin (breast or prostate), is a determinant of subcellular trafficking properties. Such studies have relevance to optimizing the design of antibodies to target HER2. PMID:25517306

Downregulation of membrane complement inhibitors CD55 and CD59 by siRNA sensitises uterine serous carcinoma overexpressing Her2/neu to complement and antibody-dependent cell cytotoxicity in vitro: implications for trastuzumab-based immunotherapy.

PubMed

Bellone, S; Roque, D; Cocco, E; Gasparrini, S; Bortolomai, I; Buza, N; Abu-Khalaf, M; Silasi, D-A; Ratner, E; Azodi, M; Schwartz, P E; Rutherford, T J; Pecorelli, S; Santin, A D

2012-04-24

We evaluated the expression of CD46, CD55 and CD59 membrane-bound complement-regulatory proteins (mCRPs) in primary uterine serous carcinoma (USC) and the ability of small interfering RNA (siRNA) against these mCRPs to sensitise USC to complement-dependent cytotoxicity (CDC) and antibody (trastuzumab)-dependent cellular cytotoxicity (ADCC) in vitro. Membrane-bound complement-regulatory proteins expression was evaluated using real-time PCR (RT-PCR) and flow cytometry, whereas Her2/neu expression and c-erbB2 gene amplification were assessed using immunohistochemistry, flow cytometry and fluorescent in-situ hybridisation. The biological effect of siRNA-mediated knockdown of mCRPs on HER2/neu-overexpressing USC cell lines was evaluated in CDC and ADCC 4-h chromium-release assays. High expression of mCRPs was found in USC cell lines when compared with normal endometrial cells (P<0.05). RT-PCR and FACS analyses demonstrated that anti-mCRP siRNAs were effective in reducing CD46, CD55 and CD59 expression on USC (P<0.05). Baseline complement-dependent cytotoxicity (CDC) against USC cell lines was low (mean ± s.e.m.=6.8 ± 0.9%) but significantly increased upon CD55 and CD59 knockdown (11.6 ± 0.8% and 10.7 ± 0.9%, respectively, P<0.05). Importantly, in the absence of complement, both CD55 and CD59, but not CD46, knockdowns significantly augmented ADCC against USC overexpressing Her2/neu. Uterine serous carcinoma express high levels of the mCRPs CD46, CD55 and CD59. Small interfering RNA inhibition of CD55 and CD59, but not CD46, sensitises USC to both CDC and ADCC in vitro, and if specifically targeted to tumour cells, may significantly increase trastuzumab-mediated therapeutic effect in vivo.

The G-protein coupled estrogen receptor, GPER: The inside and inside-out story.

PubMed

Gaudet, H M; Cheng, S B; Christensen, E M; Filardo, E J

2015-12-15

GPER possesses structural and functional characteristics shared by members of the G-protein-coupled receptor (GPCR) superfamily, the largest class of plasma membrane receptors. This newly appreciated estrogen receptor is localized predominately within intracellular membranes in most, but not all, cell types and its surface expression is modulated by steroid hormones and during tissue injury. An intracellular staining pattern is not unique among GPCRs, which employ a diverse array of molecular mechanisms that restrict cell surface expression and effectively regulating receptor binding and activation. The finding that GPER displays an intracellular predisposition has created some confusion as the estrogen-inducible transcription factors, ERα and ERβ, also reside intracellularly, and has led to complex suggestions of receptor interaction. GPER undergoes constitutive retrograde trafficking from the plasma membrane to the endoplasmic reticulum and recent studies indicate its interaction with PDZ binding proteins that sort transmembrane receptors to synaptosomes and endosomes. Genetic targeting and selective ligand approaches as well as cell models that express GPER in the absence of ERs clearly supports GPER as a bonafide "stand alone" receptor. Here, the molecular details that regulate GPER action, its cell biological activities and its implicated roles in physiological and pathological processes are reviewed. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Glucose Modulation Induces Lysosome Formation and Increases Lysosomotropic Drug Sequestration via the P-Glycoprotein Drug Transporter*

PubMed Central

Seebacher, Nicole A.; Lane, Darius J. R.; Jansson, Patric J.; Richardson, Des R.

2016-01-01

Pgp is functional on the plasma membrane and lysosomal membrane. Lysosomal-Pgp can pump substrates into the organelle, thereby trapping certain chemotherapeutics (e.g. doxorubicin; DOX). This mechanism serves as a “safe house” to protect cells against cytotoxic drugs. Interestingly, in contrast to DOX, lysosomal sequestration of the novel anti-tumor agent and P-glycoprotein (Pgp) substrate, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), induces lysosomal membrane permeabilization. This mechanism of lysosomal-Pgp utilization enhances cytotoxicity to multidrug-resistant cells. Consequently, Dp44mT has greater anti-tumor activity in drug-resistant relative to non-Pgp-expressing tumors. Interestingly, stressors in the tumor microenvironment trigger endocytosis for cell signaling to assist cell survival. Hence, this investigation examined how glucose variation-induced stress regulated early endosome and lysosome formation via endocytosis of the plasma membrane. Furthermore, the impact of glucose variation-induced stress on resistance to DOX was compared with Dp44mT and its structurally related analogue, di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC). These studies showed that glucose variation-induced stress-stimulated formation of early endosomes and lysosomes. In fact, through the process of fluid-phase endocytosis, Pgp was redistributed from the plasma membrane to the lysosomal membrane via early endosome formation. This lysosomal-Pgp actively transported the Pgp substrate, DOX, into the lysosome where it became trapped as a result of protonation at pH 5. Due to increased lysosomal DOX trapping, Pgp-expressing cells became more resistant to DOX. In contrast, cytotoxicity of Dp44mT and DpC was potentiated due to more lysosomes containing functional Pgp under glucose-induced stress. These thiosemicarbazones increased lysosomal membrane permeabilization and cell death. This mechanism has critical implications for drug-targeting in multidrug-resistant tumors where a stressful micro-environment exists. PMID:26601947

Cell membrane reactivity of MIB-1 antibody to Ki67 in human tumors: fact or artifact?

PubMed

Leonardo, Eugenio; Volante, Marco; Barbareschi, Mattia; Cavazza, Alberto; Dei Tos, Angelo Paolo; Bussolati, Gianni; Papotti, Mauro

2007-06-01

Ki67 immunohistochemistry is a widely used marker of the tumor proliferative fraction. Apart from the nuclear staining of dividing cells, MIB-1 monoclonal antibody was also found to stain the cell membrane of some tumor types. Indeed, such membrane reactivity was proposed as a diagnostic feature of hyalinizing trabecular tumor (HTT) of the thyroid. To verify the diagnostic role of Ki67 membrane pattern, 6 HTTs, 8 pulmonary sclerosing hemangiomas (SH), and 6 other human tumors with MIB-1 cell membrane immunoreactivity were stained by immunoperoxidase with 5 different anti-Ki67 antibodies in different experimental conditions. We show here that the cell membrane reactivity reported in HTT is produced only by MIB-1 and not by other antibodies to Ki67 (including commercially available mouse and rabbit monoclonal antibodies). In addition, this peculiar pattern is obtained only if the reaction is performed at room temperature, because automated immunostainers which operate at 37 degrees C do not produce any MIB-1 membrane localization. The same findings were obtained in the other 6 tumors. Conversely, sclerosing hemangioma of the lung did not produce any MIB-1 cell membrane reactivity in our hands. A cross-reactivity of the MIB-1 monoclonal antibody with an epitope expressed at the cell membrane level (rather than an artifact) seems the most likely explanation for this finding, because the immunoreactivity is generally intense and uniform in the membrane positive tumors. We conclude that when Ki67 immunohistochemistry is used for diagnostic purposes in a suspected HTT, only MIB-1 clone at room temperature should be employed.

A Dual-Action Armed Replicating Adenovirus for the Treatment of Osteoblastic Bone Metastases of Prostate Cancer

DTIC Science & Technology

2007-03-01

ligand), a membrane-bound cytokine expressed in osteoblasts/stromal cells, which binds to RANK, a cell- surface protein present on osteoclast...cocultures were incubated for 10 days and then the culture medium was employed in an ELISA to detect the osteoclast marker , tartrate- resistant acid...bone marrow stromal cells and osteoclast precursor cells. Ten days post-infection, expression of the osteoclast marker enzyme TRAP was determined

Preventing cleavage of Mer promotes efferocytosis and suppresses acute lung injury in bleomycin treated mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ye-Ji; Tissue Injury Defense Research Center, School of Medicine, Ewha Womans University, Seoul; Lee, Seung-Hae

2012-08-15

Mer receptor tyrosine kinase (Mer) regulates macrophage activation and promotes apoptotic cell clearance. Mer activation is regulated through proteolytic cleavage of the extracellular domain. To determine if membrane-bound Mer is cleaved during bleomycin-induced lung injury, and, if so, how preventing the cleavage of Mer enhances apoptotic cell uptake and down-regulates pulmonary immune responses. During bleomycin-induced acute lung injury in mice, membrane-bound Mer expression decreased, but production of soluble Mer and activity as well as expression of disintegrin and metalloproteinase 17 (ADAM17) were enhanced . Treatment with the ADAM inhibitor TAPI-0 restored Mer expression and diminished soluble Mer production. Furthermore, TAPI-0more » increased Mer activation in alveolar macrophages and lung tissue resulting in enhanced apoptotic cell clearance in vivo and ex vivo by alveolar macrophages. Suppression of bleomycin-induced pro-inflammatory mediators, but enhancement of hepatocyte growth factor induction were seen after TAPI-0 treatment. Additional bleomycin-induced inflammatory responses reduced by TAPI-0 treatment included inflammatory cell recruitment into the lungs, levels of total protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, as well as caspase-3 and caspase-9 activity and alveolar epithelial cell apoptosis in lung tissue. Importantly, the effects of TAPI-0 on bleomycin-induced inflammation and apoptosis were reversed by coadministration of specific Mer-neutralizing antibodies. These findings suggest that restored membrane-bound Mer expression by TAPI-0 treatment may help resolve lung inflammation and apoptosis after bleomycin treatment. -- Highlights: ►Mer expression is restored by TAPI-0 treatment in bleomycin-stimulated lung. ►Mer signaling is enhanced by TAPI-0 treatment in bleomycin-stimulated lung. ►TAPI-0 enhances efferocytosis and promotes resolution of lung injury.« less

Genistein inhibits cell invasion and motility by inducing cell differentiation in murine osteosarcoma cell line LM8.

PubMed

Nakamura, Atsushi; Aizawa, Junichi; Sakayama, Kenshi; Kidani, Teruki; Takata, Tomoyo; Norimatsu, Yoshiaki; Miura, Hiromasa; Masuno, Hiroshi

2012-09-26

One of the problems associated with osteosarcoma is the frequent formation of micrometastases in the lung prior to diagnosis because the development of metastatic lesions often causes a fatal outcome. Therefore, the prevention of pulmonary metastases during the early stage of tumor development is critical for the improvement of the prognosis of osteosarcoma patients. In Japan, soy is consumed in a wide variety of forms, such as miso soup and soy sauce. The purpose of this study is to investigate the effect of genistein, an isoflavone found in soy, on the invasive and motile potential of osteosarcoma cells. LM8 cells were treated for 3 days with various concentrations of genistein. The effect of genistein on cell proliferation was determined by DNA measurement in the cultures and 5-bromo-2'-deoxyuridine (BrdU) incorporation study. The assays of cell invasion and motility were performed using the cell culture inserts with either matrigel-coated membranes or uncoated membranes in the invasion chambers. The expression and secretion of MMP-2 were determined by immunohistochemistry and gelatin zymography. The subcellular localization and cellular level of β-catenin were determined by immunofluorescence and Western blot. For examining cell morphology, the ethanol-fixed cells were stained with hematoxylin-eosin (H&E). The expression of osteocalcin mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR). Genistein dose-dependently inhibits cell proliferation. Genistein-treated cells were less invasive and less motile than untreated cells. The expression and secretion of MMP-2 were lower in the genistein-treated cultures than in the untreated cultures. β-Catenin in untreated cells was located in the cytoplasm and/or nucleus, while in genistein-treated cells it was translocated near to the plasma membrane. The level of β-catenin was higher in genistein-treated cells than in untreated cells. Treatment of LM8 cells with genistein induced morphological changes, markedly decreased the formation of multilayer masses of cells, and markedly increased the expression of osteocalcin mRNA. Genistein decreased invasive and motile potential by inducing cell differentiation in LM8 cells. Genistein may be useful as an anti-metastatic drug for osteosarcoma through its differentiation-inducing effects.

TRAIL-CM4 fusion protein shows in vitro antibacterial activity and a stronger antitumor activity than solo TRAIL protein.

PubMed

Sang, Ming; Zhang, Jiaxin; Li, Bin; Chen, Yuqing

2016-06-01

A TRAIL-CM4 fusion protein in soluble form with tumor selective apoptosis and antibacterial functions was expressed in the Escherichia coli expression system and isolated through dialysis refolding and histidine-tag Nickel-affinity purification. Fresh Jurkat cells were treated with the TRAIL-CM4 fusion protein. Trypan blue staining and MTT analyses showed that, similar to a TRAIL positive control, Jurkat cell proliferation was significantly inhibited. Flow cytometry analyses using Annexin V-fluorescein revealed that Jurkat cells treated with the TRAIL-CM4 fusion protein exhibited increased apoptosis. Laser confocal microscopy showed that APB-CM4 and the fusion protein TRAIL-CM4 can bind to Jurkat cell membranes and initiate their destruction. ABP-CM4 enhances the antitumor activity of TRAIL by targeting and damaging the tumor cell membrane. In antibacterial experiments, agar well diffusion and bacterial growth inhibition curve assays revealed concentration-dependent TRAIL-CM4 antibacterial activity against Escherichia coli K12D31. The expressed TRAIL-CM4 fusion protein exhibited enhanced antitumor and antibacterial activities. Fusion protein expression allowed the two different proteins to function in combination. Copyright © 2016 Elsevier Inc. All rights reserved.

Flow cytometric single cell analysis reveals heterogeneity between adipose depots

PubMed Central

Boumelhem, Badwi B.; Assinder, Stephen J.; Bell-Anderson, Kim S.; Fraser, Stuart T.

2017-01-01

ABSTRACT Understanding adipose tissue heterogeneity is hindered by the paucity of methods to analyze mature adipocytes at the single cell level. Here, we report a system for analyzing live adipocytes from different adipose depots in the adult mouse. Single cell suspensions of buoyant adipocytes were separated from the stromal vascular fraction and analyzed by flow cytometry. Compared to other lipophilic dyes, Nile Red uptake effectively distinguished adipocyte populations. Nile Red fluorescence increased with adipocyte size and granularity and could be combined with MitoTracker® Deep Red or fluorescent antibody labeling to further dissect adipose populations. Epicardial adipocytes exhibited the least mitochondrial membrane depolarization and highest fatty-acid translocase CD36 surface expression. In contrast, brown adipocytes showed low surface CD36 expression. Pregnancy resulted in reduced mitochondrial membrane depolarisation and increased CD36 surface expression in brown and epicardial adipocyte populations respectively. Our protocol revealed unreported heterogeneity between adipose depots and highlights the utility of flow cytometry for screening adipocytes at the single cell level. PMID:28453382

[The Influence of UV-Light on the Sub-Populational Composition and Expression of Membrane Markers of Lymphocytes of Donor Blood].

PubMed

Artyukhov, V G; Basharina, O V; Zemchenkova, O V; Ryazantsev, S V

2016-01-01

The influence of UV-light (240-390 nm) at dozes of 151 and 755 J/m2 on the content of membrane markers of lymphocytes using the method of flow cytometry was investigated. It was demonstrated that during incubation of UV-irradiated lymphocytes the change of their populational and sub-populational composition occurs. Expression of complexes of CD3, CD 19,.CD8, CD 16, CD25 and CD95 increased. This increase was caused mainly by de novo synthesis. UV-light had immunostimulating effect on CD8+ T-lymphocyte population. Together with the increase of cytotoxic cells and NK-cells, activation of lymphocytes (increased amount of CD25+ and CD95+ cells) took place. Amount of cells undergone apoptosis or necrosis increased proportionally to the dosage. These changes were more expressed during incubation of lymphocytes in nutrition medium without autological blood serum, e.g. under deficiency of growth factors and antioxidants.

Cholesterol regulates HERG K+ channel activation by increasing phospholipase C β1 expression.

PubMed

Chun, Yoon Sun; Oh, Hyun Geun; Park, Myoung Kyu; Cho, Hana; Chung, Sungkwon

2013-01-01

Human ether-a-go-go-related gene (HERG) K(+) channel underlies the rapidly activating delayed rectifier K(+) conductance (IKr) during normal cardiac repolarization. Also, it may regulate excitability in many neuronal cells. Recently, we showed that enrichment of cell membrane with cholesterol inhibits HERG channels by reducing the levels of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] due to the activation of phospholipase C (PLC). In this study, we further explored the effect of cholesterol enrichment on HERG channel kinetics. When membrane cholesterol level was mildly increased in human embryonic kidney (HEK) 293 cells expressing HERG channel, the inactivation and deactivation kinetics of HERG current were not affected, but the activation rate was significantly decelerated at all voltages tested. The application of PtdIns(4,5)P2 or inhibitor for PLC prevented the effect of cholesterol enrichment, while the presence of antibody against PtdIns(4,5)P2 in pipette solution mimicked the effect of cholesterol enrichment. These results indicate that the effect of cholesterol enrichment on HERG channel is due to the depletion of PtdIns(4,5)P2. We also found that cholesterol enrichment significantly increases the expression of β1 and β3 isoforms of PLC (PLCβ1, PLCβ3) in the membrane. Since the effects of cholesterol enrichment on HERG channel were prevented by inhibiting transcription or by inhibiting PLCβ1 expression, we conclude that increased PLCβ1 expression leads to the deceleration of HERG channel activation rate via downregulation of PtdIns(4,5)P2. These results confirm a crosstalk between two plasma membrane-enriched lipids, cholesterol and PtdIns(4,5)P2, in the regulation of HERG channels.

Interface Symbiotic Membrane Formation in Root Nodules of Medicago truncatula: the Role of Synaptotagmins MtSyt1, MtSyt2 and MtSyt3

PubMed Central

Gavrin, Aleksandr; Kulikova, Olga; Bisseling, Ton; Fedorova, Elena E.

2017-01-01

Symbiotic bacteria (rhizobia) are maintained and conditioned to fix atmospheric nitrogen in infected cells of legume root nodules. Rhizobia are confined to the asymmetrical protrusions of plasma membrane (PM): infection threads (IT), cell wall-free unwalled droplets and symbiosomes. These compartments rapidly increase in surface and volume due to the microsymbiont expansion, and remarkably, the membrane resources of the host cells are targeted to interface membrane quite precisely. We hypothesized that the change in the membrane tension around the expanding microsymbionts creates a vector for membrane traffic toward the symbiotic interface. To test this hypothesis, we selected calcium sensors from the group of synaptotagmins: MtSyt1, Medicago truncatula homolog of AtSYT1 from Arabidopsis thaliana known to be involved in membrane repair, and two other homologs expressed in root nodules: MtSyt2 and MtSyt3. Here we show that MtSyt1, MtSyt2, and MtSyt3 are expressed in the expanding cells of the meristem, zone of infection and proximal cell layers of zone of nitrogen fixation (MtSyt1, MtSyt3). All three GFP-tagged proteins delineate the interface membrane of IT and unwalled droplets and create a subcompartments of PM surrounding these structures. The localization of MtSyt1 by EM immunogold labeling has shown the signal on symbiosome membrane and endoplasmic reticulum (ER). To specify the role of synaptotagmins in interface membrane formation, we compared the localization of MtSyt1, MtSyt3 and exocyst subunit EXO70i, involved in the tethering of post-Golgi secretory vesicles and operational in tip growth. The localization of EXO70i in root nodules and arbusculated roots was strictly associated with the tips of IT and the tips of arbuscular fine branches, but the distribution of synaptotagmins on membrane subcompartments was broader and includes lateral parts of IT, the membrane of unwalled droplets as well as the symbiosomes. The double silencing of synaptotagmins caused a delay in rhizobia release and blocks symbiosome maturation confirming the functional role of synaptotagmins. In conclusion: synaptotagmin-dependent membrane fusion along with tip-targeted exocytosis is operational in the formation of symbiotic interface. PMID:28265280

Expression of a plant virus non-structural protein in Saccharomyces cerevisiae causes membrane proliferation and altered mitochondrial morphology.

PubMed

Rubino, L; Di Franco, A; Russo, M

2000-01-01

Carnation Italian ringspot tombusvirus encodes a protein, referred to as 36K, that possesses a mitochondrial targeting signal and two transmembrane segments which are thought to anchor this protein to the outer membrane of the mitochondrial envelope of infected plant cells. To determine the topology of the virus protein inserted in the cell membrane, as well as the sequence requirements for targeting and insertion, an in vivo system was set up in which this could be analysed in the absence of productive virus infection. The 36K protein was expressed in the yeast Saccharomyces cerevisiae in native form or fused to the green fluorescent protein. Using a fluorescence microscope, large green-fluorescing cytoplasmic aggregates were visible which stained red when cells were treated with the vital stain MitoTracker, which is specific for mitochondria. These aggregates were shown by electron microscopy to be composed of either mitochondria or membranes. The latter type was particularly abundant for the construct in which the green fluorescent protein was fused at the N terminus of the 36K protein. Immunoelectron microscopy demonstrated that the viral protein is present in the anomalous aggregates and Western blot analysis of protein extracts showed 36K to be resistant to alkaline, urea or salt extraction, a property of integral membrane proteins.

Hyaluronan and Stone Disease

NASA Astrophysics Data System (ADS)

Asselman, Marino

2008-09-01

Kidney stones cannot be formed as long as crystals are passed in the urine. However, when crystals are retained it becomes possible for them to aggregate and form a stone. Crystals are expected to be formed not earlier than the distal tubules and collecting ducts. Studies both in vitro and in vivo demonstrate that calcium oxalate monohydrate crystals do not adhere to intact distal epithelium, but only when the epithelium is proliferating or regenerating, so that it possesses dedifferentiated cells expressing hyaluronan, osteopontin (OPN) and their mutual receptor CD44 at the apical cell membrane. The polysaccharide hyaluronan is an excellent crystal binding molecule because of its negative ionic charge. We hypothesized that the risk for crystal retention in the human kidney would be increased when tubular cells express hyaluronan at their apical cell membrane. Two different patient categories in which nephrocalcinosis frequently occurs were studied to test this hypothesis (preterm neonates and kidney transplant patients). Hyaluronan (and OPN) expression at the luminal membrane of tubular cells indeed was observed, which preceded subsequent retention of crystals in the distal tubules. Tubular nephrocalcinosis has been reported to be associated with decline of renal function and thus further studies to extend our knowledge of the mechanisms of retention and accumulation of crystals in the kidney are warranted. Ultimately, this may allow the design of new strategies for the prevention and treatment of both nephrocalcinosis and nephrolithiasis in patients.

Radioligand therapy of metastatic castration-resistant prostate cancer: current approaches.

PubMed

Awang, Zool Hilmi; Essler, Markus; Ahmadzadehfar, Hojjat

2018-05-23

Prostate Cancer is the forth most common type of cancer. Prostate-specific membrane antigen (PSMA) is anchored in the cell membrane of prostate epithelial cells. PSMA is highly expressed on prostate epithelial cells and strongly up-regulated in prostate cancer. Therefore it is an appropriate target for diagnostic and therapy of prostate cancer and its metastases. This article discusses several articles on radionuclide treatments in prostate cancer and the results on PSMA therapy with either beta or alpha emitters as a salvage therapy.

PAI-1, CAIX and VEGFA expressions as prognosis markers in oral squamous cell carcinoma.

PubMed

Peterle, Gabriela Tonini; Maia, Lucas Lima; Trivilin, Leonardo Oliveira; de Oliveira, Mayara Mota; Dos Santos, Joaquim Gasparini; Mendes, Suzanny Oliveira; Stur, Elaine; Agostini, Lidiane Pignaton; Rocha, Lília Alves; Moysés, Raquel Ajub; Cury, Patrícia Maluf; Nunes, Fábio Daumas; Louro, Iúri Drumond; Dos Santos, Marcelo; da Silva, Adriana Madeira Álvares

2018-04-25

In oral squamous cell carcinoma (OSCC), the HIF-1 complex promotes the expression of genes involved in specific mechanisms of cell survival under hypoxic conditions, such as plasminogen activator inhibitor-1 (PAI-1), carbonic anhydrase 9 (CAIX) and vascular endothelial growth factor A (VEGFA). The study aimed to investigate the presence and prognostic value of PAI-1, CAIX, and VEGFA in OSCC. Immunohistochemistry was used to analyze the expressions of these proteins in 52 tumoral tissue samples of patients with OSCC, surgically treated and followed by a minimum of 24 months after surgery. The correlations between proteins expressions and clinicopathological parameters and prognosis were analyzed. Positive PAI-1 membrane expression was significantly associated with local disease relapse (p=0.027). Multivariate analysis revealed that the positive PAI-1 membrane expression is an independent marker for local disease relapse, with approximately 14-fold increased risk when compared to negative expression (OR=14.49; CI=1.40-150.01, p=0.025). Strong PAI-1 cytoplasmic expression was significantly associated with the less differentiation grade (p=0.027). Strong CAIX membrane expression was significantly associated with local disease-free survival (p=0.038). Positive CAIX cytoplasmic expression was significantly associated with lymph node affected (p=0.025) and with disease-specific survival (p=0.022). Multivariate analysis revealed that the positive CAIX cytoplasmic expression is an independent risk factor for disease-related death, increasing their risk approximately 3-fold when compared to negative expression (HR=2.84; CI=1.02-7.87, p=0.045). Positive VEGFA cytoplasmic expression was significantly associated with less differentiation grade (p=0.035). Our results suggest a potential role for these expressions profiles as tumor prognostic markers in OSCC patients. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Expression, purification and functional reconstitution of slack sodium-activated potassium channels.

PubMed

Yan, Yangyang; Yang, Youshan; Bian, Shumin; Sigworth, Fred J

2012-11-01

The slack (slo2.2) gene codes for a potassium-channel α-subunit of the 6TM voltage-gated channel family. Expression of slack results in Na(+)-activated potassium channel activity in various cell types. We describe the purification and reconstitution of Slack protein and show that the Slack α-subunit alone is sufficient for potassium channel activity activated by sodium ions as assayed in planar bilayer membranes and in membrane vesicles.

Discovery of the ergothioneine transporter

PubMed Central

Gründemann, Dirk; Harlfinger, Stephanie; Golz, Stefan; Geerts, Andreas; Lazar, Andreas; Berkels, Reinhard; Jung, Norma; Rubbert, Andrea; Schömig, Edgar

2005-01-01

Variants of the SLC22A4 gene are associated with susceptibility to rheumatoid arthritis and Crohn's disease. SLC22A4 codes for an integral membrane protein, OCTN1, that has been presumed to carry organic cations like tetraethylammonium across the plasma membrane. Here, we show that the key substrate of this transporter is in fact ergothioneine (ET). Human OCTN1 was expressed in 293 cells. A substrate lead, stachydrine (alias proline betaine), was identified by liquid chromatography MS difference shading, a new substrate search strategy. Analysis of transport efficiency of stachydrine-related solutes, affinity, and Na+ dependence indicates that the physiological substrate is ET. Efficiency of transport of ET was as high as 195 μl per min per mg of protein. By contrast, the carnitine transporter OCTN2 from rat did not transport ET at all. Because ET is transported >100 times more efficiently than tetraethylammonium and carnitine, we propose the functional name ETT (ET transporter) instead of OCTN1. ET, all of which is absorbed from food, is an intracellular antioxidant with metal ion affinity. Its particular purpose is unresolved. Cells with expression of ETT accumulate ET to high levels and avidly retain it. By contrast, cells lacking ETT do not accumulate ET, because their plasma membrane is virtually impermeable for this compound. The real-time PCR expression profile of human ETT, with strong expression in CD71+ cells, is consistent with a pivotal function of ET in erythrocytes. Moreover, prominent expression of ETT in monocytes and SLC22A4 polymorphism associations suggest a protective role of ET in chronic inflammatory disorders. PMID:15795384

Genetics Home Reference: Larsen syndrome

MedlinePlus

... active (expressed) in the cell membranes of cartilage-forming cells (chondrocytes). Cartilage is a tough, flexible tissue ... Alanay Y, Alembik Y, Al-Madani N, Firth H, Karimi-Nejad MH, Kim CA, Leask K, Maisenbacher ...

Selective deposition and self-assembly of triblock copolymers into matrix arrays for membrane protein production.

PubMed

Andreasson-Ochsner, Mirjam; Fu, Zhikang; May, Sylvia; Xiu, Low Ying; Nallani, Madhavan; Sinner, Eva-Kathrin

2012-01-31

To improve the stability of cell membrane mimics, there has been growing interest in the use of block copolymers. Here, we present an easy approach to create an array of planar polymeric matrices capable of hosting membrane proteins. The array of polymeric matrices was formed by the selective deposition of triblock copolymers onto an array of hydrophilic islands situated within a hydrophobic background. The thickness of these matrices corresponds to the length of a single polymer chain. These polymeric matrices were used to host cell-free expressed membrane proteins, and offers a prototype from which a membrane protein array can be created for diagnostics or drug discovery purposes. © 2011 American Chemical Society

Identification of membrane proteome of Paracoccidioides lutzii and its regulation by zinc

PubMed Central

de Curcio, Juliana Santana; Silva, Marielle Garcia; Silva Bailão, Mirelle Garcia; Báo, Sônia Nair; Casaletti, Luciana; Bailão, Alexandre Mello; de Almeida Soares, Célia Maria

2017-01-01

Aim: During infection development in the host, Paracoccidioides spp. faces the deprivation of micronutrients, a mechanism called nutritional immunity. This condition induces the remodeling of proteins present in different metabolic pathways. Therefore, we attempted to identify membrane proteins and their regulation by zinc in Paracoccidioides lutzii. Materials & methods: Membranes enriched fraction of yeast cells of P. lutzii were isolated, purified and identified by 2D LC–MS/MS detection and database search. Results & conclusion: Zinc deprivation suppressed the expression of membrane proteins such as glycoproteins, those involved in cell wall synthesis and those related to oxidative phosphorylation. This is the first study describing membrane proteins and the effect of zinc deficiency in their regulation in one member of the genus Paracoccidioides. PMID:29134119

ATP7B mediates vesicular sequestration of copper: insight into biliary copper excretion.

PubMed

Cater, Michael A; La Fontaine, Sharon; Shield, Kristy; Deal, Yolanda; Mercer, Julian F B

2006-02-01

The Wilson protein (ATP7B) regulates levels of systemic copper by excreting excess copper into bile. It is not clear whether ATP7B translocates excess intrahepatic copper directly across the canalicular membrane or sequesters this copper into exocytic vesicles, which subsequently fuse with canalicular membrane to expel their contents into bile. The aim of this study was to clarify the mechanism underlying ATP7B-mediated copper detoxification by investigating endogenous ATP7B localization in the HepG2 hepatoma cell line and its ability to mediate vesicular sequestration of excess intracellular copper. Immunofluorescence microscopy was used to investigate the effect of copper concentration on the localization of endogenous ATP7B in HepG2 cells. Copper accumulation studies to determine whether ATP7B can mediate vesicular sequestration of excess intracellular copper were performed using Chinese hamster ovary cells that exogenously expressed wild-type and mutant ATP7B proteins. In HepG2 cells, elevated copper levels stimulated trafficking of ATP7B to pericanalicular vesicles and not to the canalicular membrane as previously reported. Mutation of an endocytic retrieval signal in ATP7B caused the protein to constitutively localize to vesicles and not to the plasma membrane, suggesting that a vesicular compartment(s) is the final trafficking destination for ATP7B. Expression of wild-type and mutant ATP7B caused Chinese hamster ovary cells to accumulate copper in vesicles, which subsequently undergo exocytosis, releasing copper across the plasma membrane. This report provides compelling evidence that the primary mechanism of biliary copper excretion involves ATP7B-mediated vesicular sequestration of copper rather than direct copper translocation across the canalicular membrane.

Mapping the Extracellular and Membrane Proteome Associated with the Vasculature and the Stroma in the Embryo*

PubMed Central

Soulet, Fabienne; Kilarski, Witold W.; Roux-Dalvai, Florence; Herbert, John M. J.; Sacewicz, Izabela; Mouton-Barbosa, Emmanuelle; Bicknell, Roy; Lalor, Patricia; Monsarrat, Bernard; Bikfalvi, Andreas

2013-01-01

In order to map the extracellular or membrane proteome associated with the vasculature and the stroma in an embryonic organism in vivo, we developed a biotinylation technique for chicken embryo and combined it with mass spectrometry and bioinformatic analysis. We also applied this procedure to implanted tumors growing on the chorioallantoic membrane or after the induction of granulation tissue. Membrane and extracellular matrix proteins were the most abundant components identified. Relative quantitative analysis revealed differential protein expression patterns in several tissues. Through a bioinformatic approach, we determined endothelial cell protein expression signatures, which allowed us to identify several proteins not yet reported to be associated with endothelial cells or the vasculature. This is the first study reported so far that applies in vivo biotinylation, in combination with robust label-free quantitative proteomics approaches and bioinformatic analysis, to an embryonic organism. It also provides the first description of the vascular and matrix proteome of the embryo that might constitute the starting point for further developments. PMID:23674615

Regulation of the epithelial Na+ channel by membrane tension.

PubMed

Awayda, M S; Subramanyam, M

1998-08-01

The sensitivity of alphabetagamma rat epithelial Na+ channel (rENaC) to osmotically or mechanically induced changes of membrane tension was investigated in the Xenopus oocyte expression system, using both dual electrode voltage clamp and cell-attached patch clamp methodologies. ENaC whole-cell currents were insensitive to mechanical cell swelling caused by direct injection of 90 or 180 nl of 100-mM KCl. Similarly, ENaC whole-cell currents were insensitive to osmotic cell swelling caused by a 33% decrease of bathing solution osmolarity. The lack of an effect of cell swelling on ENaC was independent of the status of the actin cytoskeleton, as ENaC remained insensitive to osmotic and mechanical cell swelling in oocytes pretreated with cytochalasin B for 2-5 h. This apparent insensitivity of ENaC to increased cell volume and changes of membrane tension was also observed at the single channel level in membrane patches subjected to negative or positive pressures of 5 or 10 in. of water. However, and contrary to the lack of an effect of cell swelling, ENaC currents were inhibited by cell shrinking. A 45-min incubation in a 260-mosmol solution (a 25% increase of solution osmolarity) caused a decrease of ENaC currents (at -100 mV) from -3.42 +/- 0.34 to -2.02 +/- 0.23 microA (n = 6). This decrease of current with cell shrinking was completely blocked by pretreatment of oocytes with cytochalasin B, indicating that these changes of current are not likely related to a direct effect of cell shrinking. We conclude that alpha beta gamma rENaC is not directly mechanosensitive when expressed in a system that can produce a channel with identical properties to those found in native epithelia.

High-expression β(1) adrenergic receptor/cell membrane chromatography method based on a target receptor to screen active ingredients from traditional Chinese medicines.

PubMed

Yue, Yuan; Xue, Hui; Wang, Xin; Yang, Qian; Song, Yanhong; Li, Xiaoni

2014-02-01

β-Adrenergic receptors are important targets for drug discovery. We have developed a new β1 -adrenergic receptor cell membrane chromatography (β1 AR-CMC) with offline ultra-performance LC (UPLC) and MS method for screening active ingredients from traditional Chinese medicines. In this study, Chinese hamster ovary-S cells with high β1 AR expression levels were established and used to prepare a cell membrane stationary phase in a β1 AR-CMC model. The retention fractions were separated and identified by the UPLC-MS system. The screening results found that isoimperatorin from Rhizoma et Radix Notopterygii was the targeted component that could act on β1 AR in similar manner of metoprolol as a control drug. In addition, the biological effects of active component were also investigated in order to search for a new type of β1 AR antagonist. It will be a useful method for drug discovery as a leading compound resource. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure-function analysis of myomaker domains required for myoblast fusion.

PubMed

Millay, Douglas P; Gamage, Dilani G; Quinn, Malgorzata E; Min, Yi-Li; Mitani, Yasuyuki; Bassel-Duby, Rhonda; Olson, Eric N

2016-02-23

During skeletal muscle development, myoblasts fuse to form multinucleated myofibers. Myomaker [Transmembrane protein 8c (TMEM8c)] is a muscle-specific protein that is essential for myoblast fusion and sufficient to promote fusion of fibroblasts with muscle cells; however, the structure and biochemical properties of this membrane protein have not been explored. Here, we used CRISPR/Cas9 mutagenesis to disrupt myomaker expression in the C2C12 muscle cell line, which resulted in complete blockade to fusion. To define the functional domains of myomaker required to direct fusion, we established a heterologous cell-cell fusion system, in which fibroblasts expressing mutant versions of myomaker were mixed with WT myoblasts. Our data indicate that the majority of myomaker is embedded in the plasma membrane with seven membrane-spanning regions and a required intracellular C-terminal tail. We show that myomaker function is conserved in other mammalian orthologs; however, related family members (TMEM8a and TMEM8b) do not exhibit fusogenic activity. These findings represent an important step toward deciphering the cellular components and mechanisms that control myoblast fusion and muscle formation.

Finding a Vulnerable Spot in HIV’s Armor by Investigating the Structure of HIV | Center for Cancer Research

Cancer.gov

The Human Immunodeficiency Virus (HIV) infects and eventually kills CD4-expressing T cells, which are essential for the immune system to function appropriately. Loss of significant numbers of T cells leads to Acquired Immunodeficiency Syndrome (AIDS), a disease that kills over two million people around the world every year. HIV infection depends on two proteins expressed on the virus surface: gp41, which sits in the virus membrane, and gp120, which sits on top of gp41. Three copies, or trimers, of each gp41/gp120 pair make up the envelope glycoprotein, Env. Env coats the virus surface and interacts with its receptor, CD4, and a co-receptor, either CCR5 or CXCR4, on the T cell. Binding to the receptors is thought to cause a structural reorganization of Env, which exposes a fusion peptide that inserts into the T cell membrane and actually forces the virus and host membranes together, initiating an infection. However, the structural details of this process are lacking.

Activation of TRPV2 and BKCa channels by the LL-37 enantiomers stimulates calcium entry and migration of cancer cells.

PubMed

Gambade, Audrey; Zreika, Sami; Guéguinou, Maxime; Chourpa, Igor; Fromont, Gaëlle; Bouchet, Ana Maria; Burlaud-Gaillard, Julien; Potier-Cartereau, Marie; Roger, Sébastien; Aucagne, Vincent; Chevalier, Stéphan; Vandier, Christophe; Goupille, Caroline; Weber, Günther

2016-04-26

Expression of the antimicrobial peptide hCAP18/LL-37 is associated to malignancy in various cancer forms, stimulating cell migration and metastasis. We report that LL-37 induces migration of three cancer cell lines by activating the TRPV2 calcium-permeable channel and recruiting it to pseudopodia through activation of the PI3K/AKT pathway. Ca2+ entry through TRPV2 cooperated with a K+ efflux through the BKCa channel. In a panel of human breast tumors, the expression of TRPV2 and LL-37 was found to be positively correlated. The D-enantiomer of LL-37 showed identical effects as the L-peptide, suggesting that no binding to a specific receptor was involved. LL-37 attached to caveolae and pseudopodia membranes and decreased membrane fluidity, suggesting that a modification of the physical properties of the lipid membrane bilayer was the underlying mechanism of its effects.

Activation of TRPV2 and BKCa channels by the LL-37 enantiomers stimulates calcium entry and migration of cancer cells

PubMed Central

Guéguinou, Maxime; Chourpa, Igor; Fromont, Gaëlle; Bouchet, Ana Maria; Burlaud-Gaillard, Julien; Potier-Cartereau, Marie; Roger, Sébastien; Aucagne, Vincent; Chevalier, Stéphan; Vandier, Christophe

2016-01-01

Expression of the antimicrobial peptide hCAP18/LL-37 is associated to malignancy in various cancer forms, stimulating cell migration and metastasis. We report that LL-37 induces migration of three cancer cell lines by activating the TRPV2 calcium-permeable channel and recruiting it to pseudopodia through activation of the PI3K/AKT pathway. Ca2+ entry through TRPV2 cooperated with a K+ efflux through the BKCa channel. In a panel of human breast tumors, the expression of TRPV2 and LL-37 was found to be positively correlated. The D-enantiomer of LL-37 showed identical effects as the L-peptide, suggesting that no binding to a specific receptor was involved. LL-37 attached to caveolae and pseudopodia membranes and decreased membrane fluidity, suggesting that a modification of the physical properties of the lipid membrane bilayer was the underlying mechanism of its effects. PMID:26993604

Fluidization of Membrane Lipids Enhances the Tolerance of Saccharomyces cerevisiae to Freezing and Salt Stress▿

PubMed Central

Rodríguez-Vargas, Sonia; Sánchez-García, Alicia; Martínez-Rivas, Jose Manuel; Prieto, Jose Antonio; Randez-Gil, Francisca

2007-01-01

Unsaturated fatty acids play an essential role in the biophysical characteristics of cell membranes and determine the proper function of membrane-attached proteins. Thus, the ability of cells to alter the degree of unsaturation in their membranes is an important factor in cellular acclimatization to environmental conditions. Many eukaryotic organisms can synthesize dienoic fatty acids, but Saccharomyces cerevisiae can introduce only a single double bond at the Δ9 position. We expressed two sunflower (Helianthus annuus) oleate Δ12 desaturases encoded by FAD2-1 and FAD2-3 in yeast cells of the wild-type W303-1A strain (trp1) and analyzed their effects on growth and stress tolerance. Production of the heterologous desaturases increased the content of dienoic fatty acids, especially 18:2Δ9,12, the unsaturation index, and the fluidity of the yeast membrane. The total fatty acid content remained constant, and the level of monounsaturated fatty acids decreased. Growth at 15°C was reduced in the FAD2 strains, probably due to tryptophan auxotrophy, since the trp1 (TRP1) transformants that produced the sunflower desaturases grew as well as the control strain did. Our results suggest that changes in the fluidity of the lipid bilayer affect tryptophan uptake and/or the correct targeting of tryptophan transporters. The expression of the sunflower desaturases, in either Trp+ or Trp− strains, increased NaCl tolerance. Production of dienoic fatty acids increased the tolerance to freezing of wild-type cells preincubated at 30°C or 15°C. Thus, membrane fluidity is an essential determinant of stress resistance in S. cerevisiae, and engineering of membrane lipids has the potential to be a useful tool of increasing the tolerance to freezing in industrial strains. PMID:17071783

Plasma membrane localization of multidrug resistance-associated protein homologs in brain capillary endothelial cells.

PubMed

Zhang, Yan; Schuetz, John D; Elmquist, William F; Miller, Donald W

2004-11-01

Several multidrug resistance-associated protein (MRP) homologs are expressed in brain microvessel endothelial cells forming the blood-brain barrier (BBB). The influence of these MRP transporters on BBB permeability will be dependent on their localization within the brain microvessel endothelial cells. Using two different and complementary approaches, the localization of various MPR homologs (MRP1, MRP4, and MRP5) was examined in primary cultured bovine brain microvessel endothelial cells (BBMECs). The first approach involved centrifugal separation of apical and basolateral plasma membranes of cultured BBMECs. The membrane fractions were then subjected to Western blot analysis for MRPs. The second approach used confocal laser scanning microscopy to determine membrane localization of MRPs in BBMECs. Results show a predominantly apical plasma membrane distribution for MRP1 and MRP5, and an almost equal distribution of MRP4 on the apical and basolateral plasma membrane of BBMECs. These studies provide the first demonstration of the localization of MRP1, MRP4, and MRP5 homologs in brain microvessel endothelial cells. The present studies also indicate that the localization of MRPs in the endothelial cells forming the BBB is different from that observed in polarized epithelial cells and thus may contribute to the reduced entry and enhanced elimination of organic anions and nucleotides in the brain.

Interleukin 18 messenger RNA and proIL-18 protein expression in chorioamniotic membranes from pregnant women with preterm prelabor rupture of membranes.

PubMed

Polettini, Jossimara; Vieira, Eliane Passarelli; Santos, Mariana Perlati dos; Peraçoli, José Carlos; Witkin, Steven S; da Silva, Márcia Guimarães

2012-04-01

To quantify the expression of IL-18 mRNA and protein in the chorioamniotic membranes of pregnant women with PPROM and correlate expression with histological chorioamnionitis. A case control study that included 42 pregnant women not in labor in the following groups: PPROM (n=28) and controls with intact membranes submitted to selective cesarean section at term (n=14). Expression of IL-18 mRNA in chorioamniotic membranes was determined by real-time polymerase chain reaction, and IL-18 protein expression was measured by western blot. Histopathological analyses and immunolocalization of IL-18 by immunohistochemistry were also performed. Analyses were performed using the Mann-Whitney or Fisher's exact tests and the group effect was considered significant if the adjusted p-values were <0.05 and the magnitude of change was greater than 2-fold for mRNA expression. IL-18 mRNA was present in 100% of samples and no difference in expression was observed between term vs. PPROM membranes (fold-change 0.12; p=0.88). In the PPROM group, no difference was observed in IL-18 mRNA regarding gestational age (fold-change 0.11; p=0.42) or the presence of histological chorioamnionitis (fold-change 0.26; p=0.15). ProIL-18 was present in all samples. IL-18 was immunolocalized to amnion, chorion and decidua cells, with intense immunohistochemical staining at the choriodecidual junction. Chorioamniotic membranes are sources of IL-18 mRNA and proIL-18, and their expression is unrelated to PPROM or histological chorioamnionitis. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

CXCR7 functions in colon cancer cell survival and migration

PubMed Central

WANG, HONGXIAN; TAO, LINYU; QI, KE; ZHANG, HAOYUN; FENG, DUO; WEI, WENJUN; KONG, HENG; CHEN, TIANWEN; LIN, QIUSHENG; CHEN, DAOJIN

2015-01-01

C-X-C chemokine receptor 7 (CXCR7) is a known promoter of tumor progression and metastasis; however, little is known about its role in colon cancer. The aim of the present study was to investigate the function of CXCR7 in human colon cancer cells. CXCR7 mRNA levels were examined in HT-29 and SW-480 human colon cancer cell lines using a quantitative polymerase chain reaction. CXCR7-knockdown was performed with small interfering RNA and lentiviral-mediated gene delivery. Immunofluorescence (IF) was conducted to examine CXCR7 expression and localization in colon cancer cells. Cell survival and migration were evaluated using MTT and migration assays, respectively. HT-29 cells expressed higher levels of CXCR7 mRNA and were therefore used in subsequent experiments. IF staining revealed that the CXCR7 protein was expressed on the cell membrane, and its expression decreased following CXCR7-short hairpin RNA lentiviral transfection. Lentiviral CXCR7-knockdown resulted in decreased cell survival and migration; however, MTT assays revealed that the lentiviral vector itself was cytotoxic. This cytotoxicity was indicated as the cell survival of the negative control group cells was significantly decreased compared with that of the blank control group cells (P<0.05). In conclusion, it is becoming increasingly evident that CXCR7 plays a role in colon cancer promotion, suggesting that CXCR7 is a promising biomarker for chemokine receptor-based drug development. Furthermore, the fact that CXCR7 is expressed on the membrane and not intracellularly makes it a prime target for drug-based intervention. PMID:26640542