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Sample records for suppressor protein caveolin-1

  1. Caveolin-1 and caveolin-2,together with three bone morphogenetic protein-related genes, may encode novel tumor suppressors down-regulated in sporadic follicular thyroid carcinogenesis.

    PubMed

    Aldred, Micheala A; Ginn-Pease, Margaret E; Morrison, Carl D; Popkie, Anthony P; Gimm, Oliver; Hoang-Vu, Cuong; Krause, Ulf; Dralle, Henning; Jhiang, Sissy M; Plass, Christoph; Eng, Charis

    2003-06-01

    Thyroid cancer is common, occurring in 1% of the general population. The relative frequencies of two of the most common subtypes of thyroid carcinoma, follicular (FTC) and papillary (PTC), vary depending on the regional prevalence of iodine deficiency. Although PTC has been more extensively studied, the etiology of sporadic FTC is poorly understood. To further elucidate this, we conducted microarray expression comparison of FTC tumors and normal thyroid tissue. Three commonly down-regulated genes, caveolin-1, caveolin-2, and GDF10/BMP3b, were chosen for further study on the basis of their localization to two chromosomal regions, 7q31.1 and 10q11.1, that commonly show loss of heterozygosity in FTC. Two additional genes, glypican-3 and a novel chordin-like gene, were also analyzed in view of their involvement in bone morphogenetic protein signaling and possible interaction with GDF10. Each of these five genes was down-regulated in >or=15 of 19 FTC tumors (79%) by semiquantitative reverse transcription-PCR. Caveolin-1 showed preferential down-regulation of its beta-isoform at both the mRNA and protein level, suggesting a distinct function for this isoform. Caveolin-1 is of particular functional interest because it has been shown to interact with PTEN, the tumor suppressor gene mutated in Cowden syndrome, an inherited multiple hamartoma syndrome that includes predisposition to FTC. Immunohistochemical analysis of 141 thyroid tumors of various histological types showed significantly fewer caveolin-1-positive tumors in FTCs, including insular type tumors, and Hurthle cell carcinomas in comparison with normal thyroid. PTC and anaplastic thyroid carcinomas did not show significant down-regulation, and thus, caveolin-1 may become a useful molecular marker to differentiate the various histologies of thyroid malignancies.

  2. Caveolin-1 inhibits epidermal growth factor-stimulated lamellipod extension and cell migration in metastatic mammary adenocarcinoma cells (MTLn3). Transformation suppressor effects of adenovirus-mediated gene delivery of caveolin-1.

    PubMed

    Zhang, W; Razani, B; Altschuler, Y; Bouzahzah, B; Mostov, K E; Pestell, R G; Lisanti, M P

    2000-07-07

    Caveolin-1 is a principal component of caveolae membranes that may function as a transformation suppressor. For example, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (D7S522; 7q31.1) that is deleted in human cancers, including mammary carcinomas. However, little is known about the role of caveolins in regulating cell movement, a critical parameter in determining metastatic potential. Here, we examine the role of caveolin-1 in cell movement. For this purpose, we employed an established cellular model, MTLn3, a metastatic rat mammary adenocarcinoma cell line. In this system, epidermal growth factor (EGF) stimulation induces rapid lamellipod extension and cell migration. Interestingly, we find that MTLn3 cells fail to express detectable levels of endogenous caveolin-1. To restore caveolin-1 expression in MTLn3 cells efficiently, we employed an inducible adenoviral gene delivery system to achieve tightly controlled expression of caveolin-1. We show here that caveolin-1 expression in MTLn3 cells inhibits EGF-stimulated lamellipod extension and cell migration and blocks their anchorage-independent growth. Under these conditions, EGF-induced activation of the p42/44 mitogen-activated protein kinase cascade is also blunted. Our results suggest that caveolin-1 expression in motile MTLn3 cells induces a non-motile phenotype.

  3. Caveolin-1 in breast cancer.

    PubMed

    Bouras, Toula; Lisanti, Michael P; Pestell, Richard G

    2004-10-01

    Caveolin-1 is the principal structural protein of caveolae, sphingolipid and cholesterol-rich invaginations of the plasma membrane involved in vesicular trafficking and signal transduction. During caveolae-dependent signaling, caveolin-1 acts as a scaffold protein to sequester and organize multi-molecular signaling complexes involved in diverse cellular activities and, as such serves as a paradigm by which numerous disease processes may be affected by ablation or mutation of caveolin-1. The hypothesis that caveolin-1 conveys a tumor/transformation suppressor function in the mammary gland is derived from several independent lines of evidence accumulated by genetic, molecular and clinical approaches. The human caveolin-1 gene maps to a suspected tumor suppressor locus (D7S522/7q31.1) frequently deleted in human breast carcinomas. In addition, up to 16% of human breast carcinomas harbor a dominant-negative mutation, P132L, in the caveolin-1 gene. Caveolin-1 RNA and protein levels are also downregulated in human primary breast carcinomas and cell lines, with reintroduction of caveolin-1 in vitro sufficient to inhibit numerous tumorigenic properties, including anchorage independent growth and invasiveness. Most recently caveolin-1 knockout mice have provided breakthroughs in understanding the dynamic role of caveolin-1 in the pathogenesis of mammary epithelial cell hyperplasia, tumorigenesis and metastasis in a vivo setting. This review concentrates on recent advances implicating caveolin-1 in breast cancer pathogenesis, with emphasis on the signaling pathways regulated during these processes.

  4. E-cadherin is required for caveolin-1-mediated down-regulation of the inhibitor of apoptosis protein survivin via reduced beta-catenin-Tcf/Lef-dependent transcription.

    PubMed

    Torres, Vicente A; Tapia, Julio C; Rodriguez, Diego A; Lladser, Alvaro; Arredondo, Cristian; Leyton, Lisette; Quest, Andrew F G

    2007-11-01

    Caveolin-1 reportedly acts as a tumor suppressor and promotes events associated with tumor progression, including metastasis. The molecular mechanisms underlying such radical differences in function are not understood. Recently, we showed that caveolin-1 inhibits expression of the inhibitor of apoptosis protein survivin via a transcriptional mechanism involving the beta-catenin-Tcf/Lef pathway. Surprisingly, while caveolin-1 expression decreased survivin mRNA and protein levels in HT29(ATCC) human colon cancer cells, this was not the case in metastatic HT29(US) cells. Survivin down-regulation was paralleled by coimmunoprecipitation and colocalization of caveolin-1 with beta-catenin in HT29(ATCC) but not HT29(US) cells. Unlike HT29(ATCC) cells, HT29(US) cells expressed small amounts of E-cadherin that accumulated in intracellular patches rather than at the cell surface. Re-expression of E-cadherin in HT29(US) cells restored the ability of caveolin-1 to down-regulate beta-catenin-Tcf/Lef-dependent transcription and survivin expression, as seen in HT29(ATCC) cells. In addition, coimmunoprecipitation and colocalization between caveolin-1 and beta-catenin increased upon E-cadherin expression in HT29(US) cells. In human embryonic kidney HEK293T and HT29(US) cells, caveolin-1 and E-cadherin cooperated in suppressing beta-catenin-Tcf/Lef-dependent transcription as well as survivin expression. Finally, mouse melanoma B16-F10 cells, another metastatic cell model with low endogenous caveolin-1 and E-cadherin levels, were characterized. In these cells, caveolin-1-mediated down-regulation of survivin in the presence of E-cadherin coincided with increased apoptosis. Thus, the absence of E-cadherin severely compromises the ability of caveolin-1 to develop activities potentially relevant to its role as a tumor suppressor.

  5. Caveolin-1 is an aggresome-inducing protein

    PubMed Central

    Tiwari, Ajit; Copeland, Courtney A.; Han, Bing; Hanson, Caroline A.; Raghunathan, Krishnan; Kenworthy, Anne K.

    2016-01-01

    Caveolin-1 (Cav1) drives the formation of flask-shaped membrane invaginations known as caveolae that participate in signaling, clathrin-independent endocytosis and mechanotransduction. Overexpression or mutations of Cav1 can lead to its mistrafficking, including its accumulation in a perinuclear compartment previously identified as the Golgi complex. Here, we show that in the case of overexpressed Cav1-GFP, this perinuclear compartment consists of cytoplasmic inclusion bodies generated in response to the accumulation of aggregates of misfolded proteins, known as aggresomes. Aggresomes containing Cav1-GFP are encased within vimentin cages, form in a microtubule-dependent manner, and are enriched in a number of key regulators of protein turnover, including ubiquitin, VCP/p97 and proteasomes. Interestingly, aggresome induction was cell-type dependent and was observed for many but not all Cav1 constructs tested. Furthermore, endogenous Cav1 accumulated in aggresomes formed in response to proteosomal inhibition. Our finding that Cav1 is both an aggresome-inducing and aggresome-localized protein provides new insights into how cells handle and respond to misfolded Cav1. They also raise the possibility that aggresome formation may contribute to some of reported phenotypes associated with overexpressed and/or mutant forms of Cav1. PMID:27929047

  6. Cholesterol and phytosterols differentially regulate the expression of caveolin 1 and a downstream prostate cell growth-suppressor gene

    PubMed Central

    Ifere, Godwin O.; Equan, Anita; Gordon, Kereen; Nagappan, Peri; Igietseme, Joseph U.; Ananaba, Godwin A.

    2010-01-01

    Background The purpose of our study was to show the distinction between the apoptotic and anti-proliferative signaling of phytosterols and cholesterol enrichment in prostate cancer cell lines, mediated by the differential transcription of caveolin-1, and N-myc downstream regulated gene1 (NDRG1), a pro-apoptotic androgen-regulated tumor suppressor. Methods PC-3 and DU145 cells were treated with sterols (cholesterol and phytosterols) for 72 h, followed by trypan blue dye exclusion measurement of necrosis and cell growth measured with a Coulter counter. Sterol induction of cell growth-suppressor gene expression was evaluated by mRNA transcription using RT-PCR, while cell cycle analysis was performed by FACS analysis. Altered expression of Ndrg1 protein was confirmed by Western blot analysis. Apoptosis was evaluated by real time RT-PCR amplification of P53, Bcl-2 gene and its related pro- and anti-apoptotic family members. Results Physiological doses (16 µM) of cholesterol and phytosterols were not cytotoxic in these cells. Cholesterol enrichment promoted cell growth (P<0.05), while phytosterols significantly induced growth-suppression (P<0.05) and apoptosis. Cell cycle analysis showed that contrary to cholesterol, phytosterols decreased mitotic subpopulations. We demonstrated for the first time that cholesterols concertedly attenuated the expression of caveolin-1(cav-1) and NDRG1 genes in both prostate cancer cell lines. Phytosterols had the opposite effect by inducing overexpression of cav-1, a known mediator of androgen-dependent signals that presumably control cell growth or apoptosis. Conclusions Cholesterol and phytosterol treatment differentially regulated the growth of prostate cancer cells and the expression of p53 and cav-1, a gene that regulates androgen-regulated signals. These sterols also differentially regulated cell cycle arrest, downstream pro-apoptotic androgen-regulated tumor-suppressor, NDRG1 suggesting that cav-1 may mediate pro-apoptotic NDRG1

  7. Protein kinase C-mediated endothelial barrier regulation is caveolin-1-dependent.

    PubMed

    Waschke, Jens; Golenhofen, Nikola; Kurzchalia, Teymuras V; Drenckhahn, Detlev

    2006-07-01

    Protein kinase C (PKC) is activated in response to various inflammatory mediators and contributes significantly to the endothelial barrier breakdown. However, the mechanisms underlying PKC-mediated permeability regulation are not well understood. We prepared microvascular myocardial endothelial cells from both wild-type (WT) and caveolin-1-deficient mice. Activation of PKC by phorbol myristate acetate (PMA) (100 nM) for 30 min induced intercellular gap formation and fragmentation of VE-cadherin immunoreactivity in WT but not in caveolin-1-deficient monolayers. To test the effect of PKC activation on VE-cadherin-mediated adhesion, we allowed VE-cadherin-coated microbeads to bind to the endothelial cell surface and probed their adhesion by laser tweezers. PMA significantly reduced bead binding to 78+/-6% of controls in WT endothelial cells without any effect in caveolin-1-deficient cells. In WT cells, PMA caused an 86+/-18% increase in FITC-dextran permeability whereas no increase in permeability was observed in caveolin-1-deficient monolayers. Inhibition of PKC by staurosporine (50 nM, 30 min) did not affect barrier functions in both WT and caveolin-1-deficient MyEnd cells. Theses data indicate that PKC activation reduces endothelial barrier functions at least in part by the reduction of VE-cadherin-mediated adhesion and demonstrate that PKC-mediated permeability regulation depends on caveolin-1.

  8. Phospholipase D1 in caveolae: regulation by protein kinase Calpha and caveolin-1.

    PubMed

    Kim, J H; Han, J M; Lee, S; Kim, Y; Lee, T G; Park, J B; Lee, S D; Suh, P G; Ryu, S H

    1999-03-23

    Caveolae are small plasma membrane invaginations that have been implicated in cell signaling, and caveolin is a principal structural component of the caveolar membrane. Previously we have demonstrated that protein kinase Calpha (PKCalpha) directly interacts with phospholipase D1 (PLD1), activating the enzymatic activity of PLD1 in the presence of phorbol 12-myristate 13-acetate (PMA) [Lee, T. G., et al. (1997) Biochim. Biophys. Acta 1347, 199-204]. In this study, using a detergent-free procedure for the purification of a caveolin-enriched membrane fraction (CEM) and immunoblot analysis, we show that PLD1 is enriched in the CEMs of 3Y1 rat fibroblasts. Purified PLD1 directly bound to a glutathione S-transferase-caveolin-1 fusion protein in in vitro binding assays. The association of PLD1 with caveolin-1 could be completely eliminated by preincubation of PLD1 with an oligopeptide corresponding to the scaffolding domain (amino acids 82-101) of caveolin-1, indicating that caveolin-1 interacts with PLD1 through the scaffolding domain. The peptide also inhibited PKCalpha-stimulated PLD1 activity and the interaction between PLD1 and PKCalpha with an IC50 of 0.5 microM. PMA elicits translocation of PKCalpha to the CEMs, inducing PLD activation through the interaction of PKCalpha with PLD1 in the CEMs. Caveolin-1 also coimmunoprecipitated with PLD1 in the absence of PMA, and the amounts of coimmunoprecipitated caveolin-1 decreased in response to treatment with PMA. Taken together, our results suggest a new mechanism for the regulation of the PKCalpha-dependent PLD activity through the molecular interaction between PLD1, PKCalpha, and caveolin-1 in caveolae.

  9. Absence of caveolin-1 alters heat shock protein expression in spontaneous mammary tumors driven by Her-2/neu expression.

    PubMed

    Ciocca, Daniel R; Cuello-Carrión, F Darío; Natoli, Anthony L; Restall, Christina; Anderson, Robin L

    2012-02-01

    In a previous study, we measured caveolin-1 protein levels, both in the normal breast and in breast cancer. The study revealed no association between caveolin-1 expression in the epithelial compartment and clinical disease outcome. However, high levels of caveolin-1 in the stromal tissue surrounding the tumor associated strongly with reduced metastasis and improved survival. Using an animal model, we found that the onset of mammary tumors driven by Her-2/neu expression was accelerated in mice lacking caveolin-1. We have analysed the heat shock protein (Hsp) response in the tumors of mice lacking caveolin-1. In all cases, the mammary tumors were estrogen and progesterone receptor negative, and the levels of Her-2/neu (evaluated by immunohistochemistry) were not different between the caveolin-1 +/+ (n = 8) and the caveolin-1 -/- (n = 7) tumors. However, a significant reduction in the extent of apoptosis was observed in mammary tumors from animals lacking caveolin-1. While Bcl-2, Bax, and survivin levels in the tumors were not different, the amount of HSPA (Hsp70) was almost double in the caveolin-1 -/- tumors. In contrast, HSPB1 (Hsp27/Hsp25) levels were significantly lower in the caveolin-1 -/- tumors. The mammary tumors from caveolin-1 null mice expressed more HSPC4 (gp96 or grp94), but HSPC1 (Hsp90), HSPA5 (grp78), HSPD1 (Hsp60), and CHOP were not altered. No significant changes in these proteins were found in the stroma surrounding these tumors. These results demonstrate that the disruption of the Cav-1 gene can cause alterations of specific Hsps as well as tumor development.

  10. Caveolin-1 and mitochondrial SOD2 (MnSOD) function as tumor suppressors in the stromal microenvironment

    PubMed Central

    Trimmer, Casey; Sotgia, Federica; Whitaker-Menezes, Diana; Balliet, Renee M; Eaton, Gregory; Martinez-Outschoorn, Ubaldo E; Pavlides, Stephanos; Howell, Anthony; Iozzo, Renato V; Pestell, Richard G; Scherer, Philipp E

    2011-01-01

    We have recently proposed a new model for understanding tumor metabolism, termed: “The Autophagic Tumor Stroma Model of Cancer Metabolism”. In this new paradigm, catabolism (autophagy) in the tumor stroma fuels the anabolic growth of aggressive cancer cells. Mechanistically, tumor cells induce autophagy in adjacent cancer-associated fibroblasts via the loss of caveolin-1 (Cav-1), which is sufficient to promote oxidative stress in stromal fibroblasts. To further test this hypothesis, here we created human Cav-1 deficient immortalized fibroblasts using a targeted sh-RNA knock-down approach. Relative to control fibroblasts, Cav-1 deficient fibroblasts dramatically promoted tumor growth in xenograft assays employing an aggressive human breast cancer cell line, namely MDA-MB-231 cells. Co-injection of Cav-1 deficient fibroblasts, with MDA-MB-231 cells, increased both tumor mass and tumor volume by ∼4-fold. Immuno-staining with CD31 indicated that this paracrine tumor promoting effect was clearly independent of angiogenesis. Mechanistically, proteomic analysis of these human Cav-1 deficient fibroblasts identified >40 protein biomarkers that were upregulated, most of which were associated with (i) myofibroblast differentiation or (ii) oxidative stress/hypoxia. In direct support of these findings, the tumor promoting effects of Cav-1 deficient fibroblasts could be functionally suppressed (nearly 2-fold) by the recombinant overexpression of SOD2 (superoxide dismutase 2), a known mitochondrial enzyme that de-activates superoxide, thereby reducing mitochondrial oxidative stress. In contrast, cytoplasmic soluble SOD1 had no effect, further highlighting a specific role for mitochondrial oxidative stress in this process. In summary, here we provide new evidence directly supporting a key role for a loss of stromal Cav-1 expression and oxidative stress in cancerassociated fibroblasts, in promoting tumor growth, which is consistent with “The Autophagic Tumor Stroma Model of

  11. Calcium regulates caveolin-1 expression at the transcriptional level

    SciTech Connect

    Yang, Xiao-Yan; Huang, Cheng-Cheng; Kan, Qi-Ming; Li, Yan; Liu, Dan; Zhang, Xue-Cheng; Sato, Toshinori; Yamagata, Sadako; Yamagata, Tatsuya

    2012-09-28

    Highlights: Black-Right-Pointing-Pointer Caveolin-1 expression is regulated by calcium signaling at the transcriptional level. Black-Right-Pointing-Pointer An inhibitor of or siRNA to L-type calcium channel suppressed caveolin-1 expression. Black-Right-Pointing-Pointer Cyclosporine A or an NFAT inhibitor markedly reduced caveolin-1 expression. Black-Right-Pointing-Pointer Caveolin-1 regulation by calcium signaling is observed in several mouse cell lines. -- Abstract: Caveolin-1, an indispensable component of caveolae serving as a transformation suppressor protein, is highly expressed in poorly metastatic mouse osteosarcoma FBJ-S1 cells while highly metastatic FBJ-LL cells express low levels of caveolin-1. Calcium concentration is higher in FBJ-S1 cells than in FBJ-LL cells; therefore, we investigated the possibility that calcium signaling positively regulates caveolin-1 in mouse FBJ-S1 cells. When cells were treated with the calcium channel blocker nifedipine, cyclosporin A (a calcineurin inhibitor), or INCA-6 (a nuclear factor of activated T-cells [NFAT] inhibitor), caveolin-1 expression at the mRNA and protein levels decreased. RNA silencing of voltage-dependent L-type calcium channel subunit alpha-1C resulted in suppression of caveolin-1 expression. This novel caveolin-1 regulation pathway was also identified in mouse NIH 3T3 cells and Lewis lung carcinoma cells. These results indicate that caveolin-1 is positively regulated at the transcriptional level through a novel calcium signaling pathway mediated by L-type calcium channel/Ca{sup 2+}/calcineurin/NFAT.

  12. The metastatic suppressor NDRG1 inhibits EMT, migration and invasion through interaction and promotion of caveolin-1 ubiquitylation in human colorectal cancer cells.

    PubMed

    Mi, L; Zhu, F; Yang, X; Lu, J; Zheng, Y; Zhao, Q; Wen, X; Lu, A; Wang, M; Zheng, M; Ji, J; Sun, J

    2017-03-27

    N-myc downstream-regulated gene 1 (NDRG1) has been reported to act as a key regulatory molecule in tumor progression-related signaling pathways, especially in tumor metastasis. However, the related mechanism has not been fully discovered yet. Herein we demonstrated that the novel molecule of cell migration and invasion, caveolin-1, has direct interaction with NDRG1 in human colorectal cancer (CRC) cells. Moreover, we discovered that NDRG1 reduces caveolin-1 protein expression through promoting its ubiquitylation and subsequent degradation via the proteasome in CRC cells. In addition, caveolin-1 mediates the suppressive function of NDRG1 in epithelial-mesenchymal transition, migration and invasion in vitro and metastasis in vivo. These results help to fulfill the potential mechanisms of NDRG1 in anti-metastatic treatment for human colorectal cancer.Oncogene advance online publication, 27 March 2017; doi:10.1038/onc.2017.74.

  13. Effect of caveolin-1 on the expression of tight junction-associated proteins in rat glioma-derived microvascular endothelial cells

    PubMed Central

    Li, Yao; Liu, Li-Bo; Ma, Teng; Wang, Ping; Xue, Yi-Xue

    2015-01-01

    Caveolin-1 affects the permeability of blood-tumor barrier (BTB) by regulating the expression of tight junction-associated proteins. However, the effect is still controversial. In the present work, we studied the regulative effect of caveolin-1 on the expression of tight junction-associated proteins and BTB via directly silencing and overexpressing of caveolin-1 by recombinant adenovirus transduction of glioma-derived microvascular endothelial cells in rat brain. The results show that the caveolin-1 downregulation resulted in decreased expression of tight junction-associated proteins, opening of tight junctions, and increasing the permeability of BTB, whereas the overexpression of caveolin-1 presented the opposite effects. Therefore, we conclude that caveolin-1 regulates the expression of tight junction-associated proteins in a positive manner, which further plays a role in the regulation of BTB permeability. This finding provides a novel therapeutic target for selectively opening of BTB. PMID:26722502

  14. The cytoplasmic domain of influenza M2 protein interacts with caveolin-1.

    PubMed

    Zou, Peng; Wu, Fan; Lu, Lu; Huang, Jing-He; Chen, Ying-Hua

    2009-06-15

    The cytoplasmic domain of influenza M2 protein (M2c) consists of 54 amino acid (aa) residues from aa44 to aa97. In this paper, M2c and its deletion mutant M2c(delta47-55) were expressed using prokaryotic expression system. First, glutaraldehyde crosslinking assay showed that M2c had multimerization potential mediated by aa47-55. Then, M2c, instead of M2c(delta47-55), directed eGFP from the whole cell localization to a predominately perinuclear region in CHO cells, which indicated that aa47-55 of M2c mediated the localization. Moreover, M2c colocalized with caveolin-1 (Cav) when CHO cells were cotransfected with Cav. A caveolin-1 binding motif phixxxxphixxphi (phi represents aromatic amino acid residues) in aa47-55 of M2c was found by sequence alignment and analysis. Further overlay ELISA result showed that M2c, but not M2c(delta47-55), bound to prokaryotically expressed cholesterol-free Cav(2-101), which illustrated the interaction could be cholesterol-independent. That was the first report of cellular protein bound to M2c.

  15. Expression of caveolin-1 induces premature cellular senescence in primary cultures of murine fibroblasts.

    PubMed

    Volonte, Daniela; Zhang, Kun; Lisanti, Michael P; Galbiati, Ferruccio

    2002-07-01

    Caveolae are vesicular invaginations of the plasma membrane. Caveolin-1 is the principal structural component of caveolae in vivo. Several lines of evidence are consistent with the idea that caveolin-1 functions as a "transformation suppressor" protein. In fact, caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). We have previously demonstrated that overexpression of caveolin-1 arrests mouse embryonic fibroblasts in the G(0)/G(1) phase of the cell cycle through activation of a p53/p21-dependent pathway, indicating a role of caveolin-1 in mediating growth arrest. However, it remains unknown whether overexpression of caveolin-1 promotes cellular senescence in vivo. Here, we demonstrate that mouse embryonic fibroblasts transgenically overexpressing caveolin-1 show: 1) a reduced proliferative lifespan; 2) senescence-like cell morphology; and 3) a senescence-associated increase in beta-galactosidase activity. These results indicate for the first time that the expression of caveolin-1 in vivo is sufficient to promote and maintain the senescent phenotype. Subcytotoxic oxidative stress is known to induce premature senescence in diploid fibroblasts. Interestingly, we show that subcytotoxic level of hydrogen peroxide induces premature senescence in NIH 3T3 cells and increases endogenous caveolin-1 expression. Importantly, quercetin and vitamin E, two antioxidant agents, successfully prevent the premature senescent phenotype and the up-regulation of caveolin-1 induced by hydrogen peroxide. Also, we demonstrate that hydrogen peroxide alone, but not in combination with quercetin, stimulates the caveolin-1 promoter activity. Interestingly, premature senescence induced by hydrogen peroxide is greatly reduced in NIH 3T3 cells harboring antisense caveolin-1. Importantly, induction of premature senescence is recovered when

  16. Caveolin-1 expression is maintained in rat and human astroglioma cell lines.

    PubMed

    Cameron, Patricia L; Liu, Changdan; Smart, Deedee K; Hantus, Stephen T; Fick, James R; Cameron, Richard S

    2002-03-01

    Caveolin-1 is the principal structural and functional component of caveolae, a plasmalemmal compartment that has been proposed to sequester lipid and protein components that participate in transmembrane signal transduction processes. Multiple studies reveal a reduction in the expression level of caveolin-1 mRNA and protein in many carcinomas as well as transformed cells. The human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). Collectively, these data have been taken to imply that caveolin-1 may function in a tumor suppressor capacity. To determine if a reduction in the expression level of caveolin-1 mRNA and protein accompanied the transformation of astrocytes, we undertook studies of two transformed rat astroglial cell lines, C6 and DI TNC(1), as well as several cell lines derived from human glioblastoma tumors: T98G, U87MG, U118MG, U138MG, and U373MG. Ultrastructural, immunolocalization, immunoblot, and Northern blot analyses demonstrated that caveolin-1 message and protein were expressed in all rat and human glioma cells. The localization pattern, buoyant density, and detergent-insolubility property of caveolin-1 protein were indistinguishable from that determined for nontransformed type 1 astrocytes in culture. Nucleotide sequence analyses of caveolin-1 cDNAs indicate that mutations are not present in the caveolin-1 sequence in any of the glioma cell types. Taken together with previous analyses, these data indicate that, at least for astrocytes, the process of transformation in and of itself is not solely sufficient to reduce the level of caveolin-1 expression, and that caveolin-1 expression in and of itself is not solely sufficient to prevent the acquisition of a transformed phenotype. Copyright 2002 Wiley-Liss, Inc.

  17. Blockade of CD26-mediated T cell costimulation with soluble caveolin-1-Ig fusion protein induces anergy in CD4{sup +}T cells

    SciTech Connect

    Ohnuma, Kei; Uchiyama, Masahiko; Hatano, Ryo; Takasawa, Wataru; Endo, Yuko; Dang, Nam H.; Morimoto, Chikao

    2009-08-21

    CD26 binds to caveolin-1 in antigen-presenting cells (APC), and that ligation of CD26 by caveolin-1 induces T cell proliferation in a TCR/CD3-dependent manner. We report herein the effects of CD26-caveolin-1 costimulatory blockade by fusion protein caveolin-1-Ig (Cav-Ig). Soluble Cav-Ig inhibits T cell proliferation and cytokine production in response to recall antigen, or allogeneic APC. Our data hence suggest that blocking of CD26-associated signaling by soluble Cav-Ig may be an effective approach as immunosuppressive therapy.

  18. Expression of Caveolin-1 Induces Premature Cellular Senescence in Primary Cultures of Murine Fibroblasts

    PubMed Central

    Volonte, Daniela; Zhang, Kun; Lisanti, Michael P.; Galbiati, Ferruccio

    2002-01-01

    Caveolae are vesicular invaginations of the plasma membrane. Caveolin-1 is the principal structural component of caveolae in vivo. Several lines of evidence are consistent with the idea that caveolin-1 functions as a “transformation suppressor” protein. In fact, caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). We have previously demonstrated that overexpression of caveolin-1 arrests mouse embryonic fibroblasts in the G0/G1 phase of the cell cycle through activation of a p53/p21-dependent pathway, indicating a role of caveolin-1 in mediating growth arrest. However, it remains unknown whether overexpression of caveolin-1 promotes cellular senescence in vivo. Here, we demonstrate that mouse embryonic fibroblasts transgenically overexpressing caveolin-1 show: 1) a reduced proliferative lifespan; 2) senescence-like cell morphology; and 3) a senescence-associated increase in β-galactosidase activity. These results indicate for the first time that the expression of caveolin-1 in vivo is sufficient to promote and maintain the senescent phenotype. Subcytotoxic oxidative stress is known to induce premature senescence in diploid fibroblasts. Interestingly, we show that subcytotoxic level of hydrogen peroxide induces premature senescence in NIH 3T3 cells and increases endogenous caveolin-1 expression. Importantly, quercetin and vitamin E, two antioxidant agents, successfully prevent the premature senescent phenotype and the up-regulation of caveolin-1 induced by hydrogen peroxide. Also, we demonstrate that hydrogen peroxide alone, but not in combination with quercetin, stimulates the caveolin-1 promoter activity. Interestingly, premature senescence induced by hydrogen peroxide is greatly reduced in NIH 3T3 cells harboring antisense caveolin-1. Importantly, induction of premature senescence is recovered when

  19. The caveolin-1 connection to cell death and survival.

    PubMed

    Quest, A F G; Lobos-González, L; Nuñez, S; Sanhueza, C; Fernández, J-G; Aguirre, A; Rodríguez, D; Leyton, L; Torres, V

    2013-02-01

    Caveolins are a family of membrane proteins required for the formation of small plasma membrane invaginations called caveolae that are implicated in cellular trafficking processes. In addition to this structural role, these scaffolding proteins modulate numerous intracellular signaling pathways; often via direct interaction with specific binding partners. Caveolin-1 is particularly well-studied in this respect and has been attributed a large variety of functions. Thus, Caveolin-1 also represents the best-characterized isoform of this family with respect to its participation in cancer. Rather strikingly, available evidence indicates that Caveolin-1 belongs to a select group of proteins that function, depending on the cellular settings, both as tumor suppressor and promoter of cellular traits commonly associated with enhanced malignant behavior, such as metastasis and multi-drug resistance. The mechanisms underlying such ambiguity in Caveolin-1 function constitute an area of great interest. Here, we will focus on discussing how Caveolin-1 modulates cell death and survival pathways and how this may contribute to a better understanding of the ambiguous role this protein plays in cancer.

  20. Caveolin-1 expression negatively regulates cell cycle progression by inducing G(0)/G(1) arrest via a p53/p21(WAF1/Cip1)-dependent mechanism.

    PubMed

    Galbiati, F; Volonté, D; Liu, J; Capozza, F; Frank, P G; Zhu, L; Pestell, R G; Lisanti, M P

    2001-08-01

    Caveolin-1 is a principal component of caveolae membranes in vivo. Caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). However, it remains unknown whether caveolin-1 plays any role in regulating cell cycle progression. Here, we directly demonstrate that caveolin-1 expression arrests cells in the G(0)/G(1) phase of the cell cycle. We show that serum starvation induces up-regulation of endogenous caveolin-1 and arrests cells in the G(0)/G(1) phase of the cell cycle. Moreover, targeted down-regulation of caveolin-1 induces cells to exit the G(0)/G(1) phase. Next, we constructed a green fluorescent protein-tagged caveolin-1 (Cav-1-GFP) to examine the effect of caveolin-1 expression on cell cycle regulation. We directly demonstrate that recombinant expression of Cav-1-GFP induces arrest in the G(0)/G(1) phase of the cell cycle. To examine whether caveolin-1 expression is important for modulating cell cycle progression in vivo, we expressed wild-type caveolin-1 as a transgene in mice. Analysis of primary cultures of mouse embryonic fibroblasts from caveolin-1 transgenic mice reveals that caveolin-1 induces 1) cells to exit the S phase of the cell cycle with a concomitant increase in the G(0)/G(1) population, 2) a reduction in cellular proliferation, and 3) a reduction in the DNA replication rate. Finally, we demonstrate that caveolin-1-mediated cell cycle arrest occurs through a p53/p21-dependent pathway. Taken together, our results provide the first evidence that caveolin-1 expression plays a critical role in the modulation of cell cycle progression in vivo.

  1. Caveolin-1 Expression Negatively Regulates Cell Cycle Progression by Inducing G0/G1 Arrest via a p53/p21WAF1/Cip1-dependent Mechanism

    PubMed Central

    Galbiati, Ferruccio; Volonte', Daniela; Liu, Jun; Capozza, Franco; Frank, Philippe G.; Zhu, Liang; Pestell, Richard G.; Lisanti, Michael P.

    2001-01-01

    Caveolin-1 is a principal component of caveolae membranes in vivo. Caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). However, it remains unknown whether caveolin-1 plays any role in regulating cell cycle progression. Here, we directly demonstrate that caveolin-1 expression arrests cells in the G0/G1 phase of the cell cycle. We show that serum starvation induces up-regulation of endogenous caveolin-1 and arrests cells in the G0/G1 phase of the cell cycle. Moreover, targeted down-regulation of caveolin-1 induces cells to exit the G0/G1 phase. Next, we constructed a green fluorescent protein-tagged caveolin-1 (Cav-1-GFP) to examine the effect of caveolin-1 expression on cell cycle regulation. We directly demonstrate that recombinant expression of Cav-1-GFP induces arrest in the G0/G1 phase of the cell cycle. To examine whether caveolin-1 expression is important for modulating cell cycle progression in vivo, we expressed wild-type caveolin-1 as a transgene in mice. Analysis of primary cultures of mouse embryonic fibroblasts from caveolin-1 transgenic mice reveals that caveolin-1 induces 1) cells to exit the S phase of the cell cycle with a concomitant increase in the G0/G1 population, 2) a reduction in cellular proliferation, and 3) a reduction in the DNA replication rate. Finally, we demonstrate that caveolin-1-mediated cell cycle arrest occurs through a p53/p21-dependent pathway. Taken together, our results provide the first evidence that caveolin-1 expression plays a critical role in the modulation of cell cycle progression in vivo. PMID:11514613

  2. Loss of Epithelial Membrane Protein 2 Aggravates Podocyte Injury via Upregulation of Caveolin-1

    PubMed Central

    Wan, Xiaoyang; Chen, Zhaohong; Choi, Won-Il; Gee, Heon Yung; Hildebrandt, Friedhelm

    2016-01-01

    Nephrotic syndrome is a CKD defined by proteinuria with subsequent hypoalbuminemia, hyperlipidemia, and edema caused by impaired renal glomerular filtration barrier function. We previously identified mutations in epithelial membrane protein 2 (EMP2) as a monogenic cause of this disease. Here, we generated an emp2-knockout zebrafish model using transcription activator-like effector nuclease–based genome editing. We found that loss of emp2 in zebrafish upregulated caveolin-1 (cav1), a major component of caveolae, in embryos and adult mesonephric glomeruli and exacerbated podocyte injury. This phenotype was partially rescued by glucocorticoids. Furthermore, overexpression of cav1 in zebrafish podocytes was sufficient to induce the same phenotype observed in emp2 homozygous mutants, which was also treatable with glucocorticoids. Similarly, knockdown of EMP2 in cultured human podocytes resulted in increased CAV1 expression and decreased podocyte survival in the presence of puromycin aminonucleoside, whereas glucocorticoid treatment ameliorated this phenotype. Taken together, we have established excessive CAV1 as a mediator of the predisposition to podocyte injury because of loss of EMP2, suggesting CAV1 could be a novel therapeutic target in nephrotic syndrome and podocyte injury. PMID:26264854

  3. Targeted downregulation of caveolin-1 is sufficient to drive cell transformation and hyperactivate the p42/44 MAP kinase cascade.

    PubMed

    Galbiati, F; Volonte, D; Engelman, J A; Watanabe, G; Burk, R; Pestell, R G; Lisanti, M P

    1998-11-16

    Caveolin-1 is a principal component of caveolae membranes in vivo. Caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). However, it remains unknown whether downregulation of caveolin-1 is sufficient to mediate cell transformation or tumorigenicity. Here, we employ an antisense approach to derive stable NIH 3T3 cell lines that express dramatically reduced levels of caveolin-1 but contain normal amounts of caveolin-2. NIH 3T3 cells harboring antisense caveolin-1 exhibit anchorage-independent growth, form tumors in immunodeficient mice and show hyperactivation of the p42/44 MAP kinase cascade. Importantly, transformation induced by caveolin-1 downregulation is reversed when caveolin-1 protein levels are restored to normal by loss of the caveolin-1 antisense vector. In addition, we show that in normal NIH 3T3 cells, caveolin-1 expression levels are tightly regulated by specific growth factor stimuli and cell density. Our results suggest that upregulation of caveolin-1 may be important in mediating contact inhibition and negatively regulating the activation state of the p42/44 MAP kinase cascade.

  4. Targeted downregulation of caveolin-1 is sufficient to drive cell transformation and hyperactivate the p42/44 MAP kinase cascade.

    PubMed Central

    Galbiati, F; Volonte, D; Engelman, J A; Watanabe, G; Burk, R; Pestell, R G; Lisanti, M P

    1998-01-01

    Caveolin-1 is a principal component of caveolae membranes in vivo. Caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes. Interestingly, the human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). However, it remains unknown whether downregulation of caveolin-1 is sufficient to mediate cell transformation or tumorigenicity. Here, we employ an antisense approach to derive stable NIH 3T3 cell lines that express dramatically reduced levels of caveolin-1 but contain normal amounts of caveolin-2. NIH 3T3 cells harboring antisense caveolin-1 exhibit anchorage-independent growth, form tumors in immunodeficient mice and show hyperactivation of the p42/44 MAP kinase cascade. Importantly, transformation induced by caveolin-1 downregulation is reversed when caveolin-1 protein levels are restored to normal by loss of the caveolin-1 antisense vector. In addition, we show that in normal NIH 3T3 cells, caveolin-1 expression levels are tightly regulated by specific growth factor stimuli and cell density. Our results suggest that upregulation of caveolin-1 may be important in mediating contact inhibition and negatively regulating the activation state of the p42/44 MAP kinase cascade. PMID:9822607

  5. CAVEOLIN-1 REGULATES HIV-1 TAT-INDUCED ALTERATIONS OF TIGHT JUNCTION PROTEIN EXPRESSION VIA MODULATION OF THE RAS SIGNALING

    PubMed Central

    Zhong, Yu; Smart, Eric J.; Weksler, Babette; Couraud, Pierre-Olivier; Hennig, Bernhard; Toborek, Michal

    2009-01-01

    The blood-brain barrier (BBB) is the critical structure for preventing HIV trafficking into the brain. Specific HIV proteins, such as Tat protein, can contribute to the dysfunction of tight junctions at the BBB and HIV entry into the brain. Tat is released by HIV-1 infected cells and can interact with a variety of cell surface receptors activating several signal transduction pathways, including those localized in caveolae. The present study focused on the mechanisms of Tat-induced caveolae-associated Ras signaling at the level of the BBB. Treatment with Tat activated the Ras pathway in human brain microvascular endothelial cells (HBMEC). However, caveolin-1 silencing markedly attenuated these effects. Because the integrity of the brain endothelium is regulated by intercellular tight junctions, these structural elements of the BBB were also evaluated in the present study. Exposure to Tat diminished the expression of several tight junction proteins, namely, occludin, zonula occludens (ZO)-1, and ZO-2 in the caveolar fraction of HBMEC. These effects were effectively protected by pharmacological inhibition of the Ras signaling and by silencing of caveolin-1. The present data indicate the importance of caveolae-associated signaling in the disruption of tight junctions upon Tat exposure. They also demonstrate that caveolin-1 may constitute an early and critical modulator that controls signaling pathways leading to the disruption of tight junction proteins. Thus, caveolin-1 may provide an effective target to protect against Tat-induced HBMEC dysfunction and the disruption of the BBB in HIV-1-infected patients. PMID:18667611

  6. Loss of caveolin-1 alters extracellular matrix protein expression and ductal architecture in murine mammary glands

    PubMed Central

    Thompson, Christopher; Hielscher, Abigail

    2017-01-01

    The extracellular matrix (ECM) is abnormal in breast tumors and has been reported to contribute to breast tumor progression. One factor, which may drive ongoing matrix synthesis in breast tumors, is the loss of stromal caveolin-1 (cav-1), a scaffolding protein of caveolae, which has been linked to breast tumor aggressiveness. To determine whether loss of cav-1 results in the abnormal expression of matrix proteins, mammary glands from cav- 1-/- and cav- 1 +/+ mice were investigated for differences in expression of several ECM proteins. In addition, the presence of myofibroblasts, changes in the vessel density, and differences in duct number and size were assessed in the mammary glands of both animal models. Using immunohistochemistry, expression of fibronectin, tenascin-C, collagens and αSMA were significantly increased in the mammary glands of cav-1-/- mice. Second harmonic generation revealed more organized collagen fibers in cav-1 -/- glands and supported immunohistochemical analyses of increased collagen abundance in the glands of cav-1 -/- mice. Analysis of the ductal structure demonstrated a significant increase in the number of proliferating ducts in addition to significant increases in the duct circumference and area in cav-1 -/- glands compared to cav- 1 +/+ glands. Differences in microvessel density weren’t apparent between the animal models. In summary, we found that the loss of cav-1 resulted in increased ECM and α-SMA protein expression in murine mammary glands. Furthermore, we found that an abnormal ductal architecture accompanied the loss of cav-1. These data support a role for cav-1 in maintaining mammary gland structure. PMID:28187162

  7. Loss of caveolin-1 alters extracellular matrix protein expression and ductal architecture in murine mammary glands.

    PubMed

    Thompson, Christopher; Rahim, Sahar; Arnold, Jeremiah; Hielscher, Abigail

    2017-01-01

    The extracellular matrix (ECM) is abnormal in breast tumors and has been reported to contribute to breast tumor progression. One factor, which may drive ongoing matrix synthesis in breast tumors, is the loss of stromal caveolin-1 (cav-1), a scaffolding protein of caveolae, which has been linked to breast tumor aggressiveness. To determine whether loss of cav-1 results in the abnormal expression of matrix proteins, mammary glands from cav- 1-/- and cav- 1 +/+ mice were investigated for differences in expression of several ECM proteins. In addition, the presence of myofibroblasts, changes in the vessel density, and differences in duct number and size were assessed in the mammary glands of both animal models. Using immunohistochemistry, expression of fibronectin, tenascin-C, collagens and αSMA were significantly increased in the mammary glands of cav-1-/- mice. Second harmonic generation revealed more organized collagen fibers in cav-1 -/- glands and supported immunohistochemical analyses of increased collagen abundance in the glands of cav-1 -/- mice. Analysis of the ductal structure demonstrated a significant increase in the number of proliferating ducts in addition to significant increases in the duct circumference and area in cav-1 -/- glands compared to cav- 1 +/+ glands. Differences in microvessel density weren't apparent between the animal models. In summary, we found that the loss of cav-1 resulted in increased ECM and α-SMA protein expression in murine mammary glands. Furthermore, we found that an abnormal ductal architecture accompanied the loss of cav-1. These data support a role for cav-1 in maintaining mammary gland structure.

  8. Caveolin1/protein arginine methyltransferase1/sirtuin1 axis as a potential target against endothelial dysfunction.

    PubMed

    Charles, Soniya; Raj, Vijay; Arokiaraj, Jesu; Mala, Kanchana

    2017-01-23

    Endothelial dysfunction (ED), an established response to cardiovascular risk factors, is characterized by increased levels of soluble molecules secreted by endothelial cells (EC). Evidence suggest that ED is an independent predictor of cardiac events and that it is associated with a deficiency in production or bioavailability of nitric oxide (NO) and/or an imbalance in the relative contribution of endothelium-derived relaxing and contracting factors. ED can be reversed by treating cardiovascular risk factors, hence, beyond ambiguity, ED contributes to initiation and progression of atherosclerotic disease. Majority of cardiovascular risk factors act by a common pathway, oxidative stress (OS), characterized by an imbalance in bioavailability of NO and reactive oxygen species (ROS). Enhanced ROS, through several mechanisms, alters competence of EC that leads to ED, reducing its potential to maintain homeostasis and resulting in development of cardiovascular disease (CVD). Influential mechanisms that have been implicated in the development of ED include (i) presence of elevated levels of NOS inhibitor, asymmetric dimethylarginine (ADMA) due to augmented enzyme activity of protein arginine methyl transferase-1 (PRMT1); (ii) decrease in NO generation by endothelial nitric oxide synthase (eNOS) uncoupling, or by reaction of NO with free radicals and (iii) impaired post translational modification of protein (PTM) such as eNOS, caveolin-1 (cav1) and sirtuin-1 (SIRT1). However, the inter-related mechanisms that concur to developing ED is yet to be understood. The events that possibly overlay include OS-induced sequestration of SIRT1 to caveolae facilitating cav1-SIRT1 association; potential increase in lysine acetylation of enzymes such as eNOS and PRMT1 leading to enhanced ADMA formation; imbalance in acetylation-methylation ratio (AMR); diminished NO generation and ED. Here we review current literature from research showing interdependent association between cav1-PRMT1

  9. Caveolin-1 and prostate cancer progression.

    PubMed

    Freeman, Michael R; Yang, Wei; Di Vizio, Dolores

    2012-01-01

    Caveolin-1 was identified in the 1990s as a marker of aggressive prostate cancer. The caveolin-1 protein localizes to vesicular structures called caveolae and has been shown to bind and regulate many signaling proteins involved in oncogenesis. Caveolin-1 also has lipid binding properties and mediates aspects of cholesterol and fatty acid metabolism and can elicit biological responses in a paracrine manner when secreted. Caveolin-1 is also present in the serum of prostate cancer patients and circulating levels correlate with extent of disease. Current evidence indicates that increased expression of caveolin-1 in prostate adenocarcinoma cells and commensurate downregulation of the protein in prostate stroma, mediate progression to the castration-resistant phase of prostate cancer through diverse pathways. This chapter summarizes the current state of our understanding of the cellular and physiologic mechanisms in which caveolin-1 participates in the evolution of prostate cancer cell phenotypes.

  10. Divergent expression and roles for caveolin-1 in mouse hepatocarcinoma cell lines with varying invasive ability

    SciTech Connect

    Zhou Huimin; Jia Li; Wang Shujing; Wang Hongmei; Chu Haiying; Hu Yichuan; Cao Jun; Zhang Jianing . E-mail: jnzhang@dlmedu.edu.cn

    2006-06-23

    Caveolin-1 is the major component protein of caveolae and associated with a lot of cellular events such as endocytosis, cholesterol homeostasis, signal transduction, and tumorigenesis. The majority of results suggest that caveolin-1 might not only act as a tumor suppressor gene but also a promoting metastasis gene. In this study, the divergent expression and roles of caveolin-1 were investigated in mouse hepatocarcinoma cell lines Hca-F, Hca-P, and Hepa1-6, which have high, low, and no metastatic potential in the lymph nodes, as compared with normal mouse liver cell line IAR-20. The results showed that expression of caveolin-1 mRNA and protein along with the amount of caveolae number in Hca-F cells was higher than that in Hca-P cells, but was not detectable in Hepa1-6 cells. When caveolin-1 expression in Hca-F cells was down-regulated by RNAi approach, Hca-F cells proliferation rate in vitro declined and the expression of lymphangiogenic factor VEGFA in Hca-F decreased as well. Furthermore, in vivo implantation assay indicated that reduction of caveolin-1 expression in Hca-F prevented the lymphatic metastasis tumor burden of Hca-F cells in 615 mice. These results suggest that caveolin-1 facilities the lymphatic metastasis ability of mouse hepatocarcinoma cells via regulation tumor cell growth and VEGFA expression.

  11. Up-regulation of endothelial monocyte chemoattractant protein-1 by coplanar PCB77 is caveolin-1-dependent

    SciTech Connect

    Majkova, Zuzana; Smart, Eric; Toborek, Michal; Hennig, Bernhard

    2009-05-15

    Atherosclerosis, the primary cause of heart disease and stroke is initiated in the vascular endothelium, and risk factors for its development include environmental exposure to persistent organic pollutants. Caveolae are membrane microdomains involved in regulation of many signaling pathways, and in particular in endothelial cells. We tested the hypothesis that intact caveolae are required for coplanar PCB77-induced up-regulation of monocyte chemoattractant protein-1 (MCP-1), an endothelium-derived chemokine that attracts monocytes into sub-endothelial space in early stages of the atherosclerosis development. Atherosclerosis-prone LDL-R{sup -/-} mice (control) or caveolin-1{sup -/-}/LDL-R{sup -/-} mice were treated with PCB77. PCB77 induced aortic mRNA expression and plasma protein levels of MCP-1 in control, but not caveolin-1{sup -/-}/LDL-R{sup -/-} mice. To study the mechanism of this effect, primary endothelial cells were used. PCB77 increased MCP-1 levels in endothelial cells in a time- and concentration-dependent manner. This effect was abolished by caveolin-1 silencing using siRNA. Also, MCP-1 up-regulation by PCB77 was prevented by inhibiting p38 and c-Jun N-terminal kinase (JNK), but not ERK1/2, suggesting regulatory functions via p38 and JNK MAPK pathways. Finally, pre-treatment of endothelial cells with the aryl hydrocarbon receptor (AhR) inhibitor {alpha}-naphthoflavone ({alpha}-NF) partially blocked MCP-1 up-regulation. Thus, our data demonstrate that coplanar PCB77 can induce MCP-1 expression by endothelial cells and that this effect is mediated by AhR, as well as p 38 and JNK MAPK pathways. Intact caveolae are required for these processes both in vivo and in vitro. This further supports a key role for caveolae in vascular inflammation induced by persistent organic pollutants.

  12. Opposing effects of protein kinase Calpha and protein kinase Cepsilon on collagen expression by human lung fibroblasts are mediated via MEK/ERK and caveolin-1 signaling.

    PubMed

    Tourkina, Elena; Gooz, Pal; Pannu, Jaspreet; Bonner, Michael; Scholz, Dimitri; Hacker, Sharon; Silver, Richard M; Trojanowska, Maria; Hoffman, Stanley

    2005-04-08

    The roles of MEK, ERK, the epsilon and alpha isoforms of protein kinase C (PKC), and caveolin-1 in regulating collagen expression were studied in normal lung fibroblasts. Knocking down caveolin-1 gave particularly striking results. A 70% decrease caused a 5-fold increase in MEK/ERK activation and collagen expression. The combined data reveal a branched signaling pathway. In its central portion MEK activates ERK, leading to increased collagen expression. Two branches converge on MEK/ERK. In one, increased PKCepsilon leads to MEK/ERK activation. In another, increased PKCalpha induces caveolin-1 expression, which in turn inhibits MEK/ERK activation and collagen expression. Lung fibroblasts from scleroderma patients with pulmonary fibrosis showed altered signaling. Consistent with their overexpression of collagen, scleroderma lung fibroblasts contain more activated MEK/ERK and less caveolin-1 than normal lung fibroblasts. Because cutaneous fibrosis is the hallmark of scleroderma, we also studied dermal fibroblasts. As in lung, there was more activated MEK/ERK in cells from scleroderma patients than in control cells, and MEK inhibition decreased collagen expression. However, the distinctive levels of PKCepsilon, PKCalpha, and caveolin-1 in lung and dermal fibroblasts from scleroderma patients and control subjects indicate that the links between these signaling proteins and MEK/ERK must function differently in the four cell types. Finally, we confirmed the relevance of these signaling cascades in vivo. The combined results demonstrate that a branched signaling pathway involving MEK, ERK, PKCepsilon, PKCalpha, and caveolin-1 regulates collagen expression in normal lung tissue and is perturbed during fibrosis.

  13. Sclareol inhibits cell proliferation and sensitizes cells to the antiproliferative effect of bortezomib via upregulating the tumor suppressor caveolin-1 in cervical cancer cells

    PubMed Central

    Zhang, Ting; Wang, Ting; Cai, Peiling

    2017-01-01

    The anticancer effect of sclareol has long been reported, however, the exact mechanisms underlying the antitumorigenic effect of sclareol in cervical carcinoma remain to be fully elucidated. The present study analyzed cell proliferation and cell apoptosis by MTT and FITC-Annexin V assays. The protein levels of caveolin-1 (Cav-1) and copper-zinc superoxide dismutase (SOD)1 were determined by western blotting, and the interaction of Cav1 and HSC70 was investigated by co-immunoprecipitation experiments. The present study found that sclareol inhibited cell proliferation and induced apoptosis in HeLa cells. Two cancer-associated proteins, Cav1 and SOD1 were identified as potential targets of sclareol in HeLa cells. The expression of Cav1 increased when the cells were treated with sclareol, and the protein level of SOD1 was negatively correlated with Cav1. The overexpression of Cav1 enhanced the sensitivity of the HeLa cells to sclareol treatment and downregulated the protein level of SOD1, which exhibited potential associations between Cav1 and SOD1. In addition, sclareol significantly sensitized several cancer cells to the anticancer effect of bortezomib by targeting Cav1 and SOD1. Taken together, the results of the present study demonstrated that sclareol inhibited tumor cell growth through the upregulation of Cav1, and provides a potential therapeutic target for human cancer. PMID:28440485

  14. Ceramide displaces cholesterol from lipid rafts and decreases the association of the cholesterol binding protein caveolin-1.

    PubMed

    Yu, Cuijuan; Alterman, Michail; Dobrowsky, Rick T

    2005-08-01

    Addition of exogenous ceramide causes a significant displacement of cholesterol in lipid raft model membranes. However, whether ceramide-induced cholesterol displacement is sufficient to alter the protein composition of caveolin-enriched lipid raft membranes is unknown. Therefore, we examined whether increasing endogenous ceramide levels with bacterial sphingomyelinase (bSMase) depleted cholesterol and changed the protein composition of caveolin-enriched membranes (CEMs) isolated from immortalized Schwann cells. bSMase increased ceramide levels severalfold and decreased the cholesterol content of detergent-insoluble CEMs by 25-50% within 2 h. To examine the effect of ceramide on the protein composition of the CEMs, we performed a quantitative proteomic analysis using stable isotope labeling of cells in culture and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Although ceramide rapidly depleted lipid raft cholesterol, the levels of the cholesterol binding protein caveolin-1 (Cav-1) decreased by 25% only after 8 h. Importantly, replenishing the cells with cholesterol rapidly reversed the loss of Cav-1 from the CEMs. Ceramide-induced cholesterol depletion increased the association of 5'-nucleotidase and ATP synthase beta-subunit with the CEMs but had a minimal effect on changing the abundance of other lipid raft proteins, such as flotillin-1 and G-proteins. These results suggest that the ceramide-induced loss of cholesterol from CEMs may contribute to altering the lipid raft proteome.

  15. Expression and potential correlation among Forkhead box protein M1, Caveolin-1 and E-cadherin in colorectal cancer

    PubMed Central

    Zhang, Jing; Zhang, Kundong; Zhou, Lisheng; Wu, Weidong; Jiang, Tao; Cao, Jun; Huang, Kejian; Qiu, Zhengjun; Huang, Chen

    2016-01-01

    The aim of the present study was to investigate the expression and functions of Forkhead box protein M1 (FoxM1), Caveolin-1 (Cav-1) and E-cadherin in colorectal cancer (CRC), and to determine the correlations among these proteins in CRC development and progression. The protein expression of FoxM1, Cav-1 and E-cadherin was identified using a human CRC and normal tissue microarray. A standard immunohistochemistry assay was performed employing anti-FoxM1, anti-Cav-1 and anti-E-cadherin antibodies. The clinicopathological significance of FoxM1, Cav-1 and E-cadherin in CRC was determined, and correlations were investigated between FoxM1 and Cav-1, FoxM1 and E-cadherin, Cav-1 and E-cadherin, respectively. The level of FoxM1, Cav-1 and E-Cadherin protein expression in CRC was found to be associated with pathological grade, tumor clinical stages and the presence of metastasis, respectively. Elevated expression of FoxM1 and Cav-1 was observed in the CRC tissues, and a significant correlation was found between the two proteins in CRC. However, it was also observed that FoxM1 was overexpressed while E-cadherin expression was low, indicating that there was a negative correlation between FoxM1 expression and E-cadherin expression. Moreover, there was also a negative correlation between Cav-1 and E-cadherin expression. Overall, the elevated expression of FoxM1 and Cav-1 in a human CRC microarray provided novel clinical evidence to elucidate the fact that they may play a critical role in the development and progression of CRC by negatively regulating E-cadherin expression. Furthermore, the positive correlation between FoxM1 and Cav-1 suggested that the proteins may constitute a novel signaling pathway in human CRC. PMID:27698803

  16. Caveolin-1 - A Novel Interacting Partner of Organic Cation/Carnitine Transporter (Octn2): Effect of Protein Kinase C on This Interaction in Rat Astrocytes

    PubMed Central

    Czeredys, Magdalena; Samluk, Łukasz; Michalec, Katarzyna; Tułodziecka, Karolina; Skowronek, Krzysztof; Nałęcz, Katarzyna A.

    2013-01-01

    OCTN2 - the Organic Cation Transporter Novel family member 2 (SLC22A5) is known to be a xenobiotic/drug transporter. It transports as well carnitine - a compound necessary for oxidation of fatty acids and mutations of its gene cause primary carnitine deficiency. Octn2 regulation by protein kinase C (PKC) was studied in rat astrocytes - cells in which β-oxidation takes place in the brain. Activation of PKC with phorbol ester stimulated L-carnitine transport and increased cell surface presence of the transporter, although no PKC-specific phosphorylation of Octn2 could be detected. PKC activation resulted in an augmented Octn2 presence in cholesterol/sphingolipid-rich microdomains of plasma membrane (rafts) and increased co-precipitation of Octn2 with raft-proteins, caveolin-1 and flotillin-1. Deletion of potential caveolin-1 binding motifs pointed to amino acids 14–22 and 447–454 as the caveolin-1 binding sites within Octn2 sequence. A direct interaction of Octn2 with caveolin-1 in astrocytes upon PKC activation was detected by proximity ligation assay, while such an interaction was excluded in case of flotillin-1. Functioning of a multi-protein complex regulated by PKC has been postulated in rOctn2 trafficking to the cell surface, a process which could be important both under physiological conditions, when carnitine facilitates fatty acids catabolism and controls free Coenzyme A pool as well as in pathology, when transport of several drugs can induce secondary carnitine deficiency. PMID:24349196

  17. Soy protein isolate down-regulates caveolin-1 expression to suppress osteoblastic cell senescence pathways

    USDA-ARS?s Scientific Manuscript database

    It has been suggested that the beneficial effects of soy protein isolate (SPI) on bone quality might be due to either stimulation of estrogenic signaling via isoflavones or through a novel and as yet characterized non-estrogenic pathway. We report here that SPI-fed rat serum inhibited osteoblastic c...

  18. Caveolin-1 is enriched in the peroxisomal membrane of rat hepatocytes.

    PubMed

    Woudenberg, Jannes; Rembacz, Krzysztof P; van den Heuvel, Fiona A J; Woudenberg-Vrenken, Titia E; Buist-Homan, Manon; Geuken, Mariska; Hoekstra, Mark; Deelman, Leo E; Enrich, Carlos; Henning, Rob H; Moshage, Han; Faber, Klaas Nico

    2010-05-01

    Caveolae are a subtype of cholesterol-enriched lipid microdomains/rafts that are routinely detected as vesicles pinching off from the plasma membrane. Caveolin-1 is an essential component of caveolae. Hepatic caveolin-1 plays an important role in liver regeneration and lipid metabolism. Expression of caveolin-1 in hepatocytes is relatively low, and it has been suggested to also reside at other subcellular locations than the plasma membrane. Recently, we found that the peroxisomal membrane contains lipid microdomains. Like caveolin-1, hepatic peroxisomes are involved in lipid metabolism. Here, we analyzed the subcellular location of caveolin-1 in rat hepatocytes. The subcellular location of rat hepatocyte caveolin-1 was analyzed by cell fractionation procedures, immunofluorescence, and immuno-electron microscopy. Green fluorescent protein (GFP)-tagged caveolin-1 was expressed in rat hepatocytes. Lipid rafts were characterized after Triton X-100 or Lubrol WX extraction of purified peroxisomes. Fenofibric acid-dependent regulation of caveolin-1 was analyzed. Peroxisome biogenesis was studied in rat hepatocytes after RNA interference-mediated silencing of caveolin-1 and caveolin-1 knockout mice. Cell fractionation and microscopic analyses reveal that caveolin-1 colocalizes with peroxisomal marker proteins (catalase, the 70 kDa peroxisomal membrane protein PMP70, the adrenoleukodystrophy protein ALDP, Pex14p, and the bile acid-coenzyme A:amino acid N-acyltransferase BAAT) in rat hepatocytes. Artificially expressed GFP-caveolin-1 accumulated in catalase-positive organelles. Peroxisomal caveolin-1 is associated with detergent-resistant microdomains. Caveolin-1 expression is strongly repressed by the peroxisome proliferator-activated receptor-alpha agonist fenofibric acid. Targeting of peroxisomal matrix proteins and peroxisome number and shape were not altered in rat hepatocytes with 70%-80% reduced caveolin-1 levels and in livers of caveolin-1 knockout mice. Caveolin-1

  19. Caveolin-1-deficient Mice Show Accelerated Mammary Gland Development During Pregnancy, Premature Lactation, and Hyperactivation of the Jak-2/STAT5a Signaling Cascade

    PubMed Central

    Park, David S.; Lee, Hyangkyu; Frank, Philippe G.; Razani, Babak; Nguyen, Andrew V.; Parlow, Albert F.; Russell, Robert G.; Hulit, James; Pestell, Richard G.; Lisanti, Michael P.

    2002-01-01

    It is well established that mammary gland development and lactation are tightly controlled by prolactin signaling. Binding of prolactin to its cognate receptor (Prl-R) leads to activation of the Jak-2 tyrosine kinase and the recruitment/tyrosine phosphorylation of STAT5a. However, the mechanisms for attenuating the Prl-R/Jak-2/STAT5a signaling cascade are just now being elucidated. Here, we present evidence that caveolin-1 functions as a novel suppressor of cytokine signaling in the mammary gland, akin to the SOCS family of proteins. Specifically, we show that caveolin-1 expression blocks prolactin-induced activation of a STAT5a-responsive luciferase reporter in mammary epithelial cells. Furthermore, caveolin-1 expression inhibited prolactin-induced STAT5a tyrosine phosphorylation and DNA binding activity, suggesting that caveolin-1 may negatively regulate the Jak-2 tyrosine kinase. Because the caveolin-scaffolding domain bears a striking resemblance to the SOCS pseudosubstrate domain, we examined whether Jak-2 associates with caveolin-1. In accordance with this homology, we demonstrate that Jak-2 cofractionates and coimmunoprecipitates with caveolin-1. We next tested the in vivo relevance of these findings using female Cav-1 (−/−) null mice. If caveolin-1 normally functions as a suppressor of cytokine signaling in the mammary gland, then Cav-1 null mice should show premature development of the lobuloalveolar compartment because of hyperactivation of the prolactin signaling cascade via disinhibition of Jak-2. In accordance with this prediction, Cav-1 null mice show accelerated development of the lobuloalveolar compartment, premature milk production, and hyperphosphorylation of STAT5a (pY694) at its Jak-2 phosphorylation site. In addition, the Ras-p42/44 MAPK cascade is hyper-activated. Because a similar premature lactation phenotype is observed in SOCS1 (−/−) null mice, we conclude that caveolin-1 is a novel suppressor of cytokine signaling. PMID:12388746

  20. Bile acids down-regulate caveolin-1 in esophageal epithelial cells through sterol responsive element-binding protein.

    PubMed

    Prade, Elke; Tobiasch, Moritz; Hitkova, Ivana; Schäffer, Isabell; Lian, Fan; Xing, Xiangbin; Tänzer, Marc; Rauser, Sandra; Walch, Axel; Feith, Marcus; Post, Stefan; Röcken, Christoph; Schmid, Roland M; Ebert, Matthias P A; Burgermeister, Elke

    2012-05-01

    Bile acids are synthesized from cholesterol and are major risk factors for Barrett adenocarcinoma (BAC) of the esophagus. Caveolin-1 (Cav1), a scaffold protein of membrane caveolae, is transcriptionally regulated by cholesterol via sterol-responsive element-binding protein-1 (SREBP1). Cav1 protects squamous epithelia by controlling cell growth and stabilizing cell junctions and matrix adhesion. Cav1 is frequently down-regulated in human cancers; however, the molecular mechanisms that lead to this event are unknown. We show that the basal layer of the nonneoplastic human esophageal squamous epithelium expressed Cav1 mainly at intercellular junctions. In contrast, Cav1 was lost in 95% of tissue specimens from BAC patients (n = 100). A strong cytoplasmic expression of Cav1 correlated with poor survival in a small subgroup (n = 5) of BAC patients, and stable expression of an oncogenic Cav1 variant (Cav1-P132L) in the human BAC cell line OE19 promoted proliferation. Cav1 was also detectable in immortalized human squamous epithelial, Barrett esophagus (CPC), and squamous cell carcinoma cells (OE21), but was low in BAC cell lines (OE19, OE33). Mechanistically, bile acids down-regulated Cav1 expression by inhibition of the proteolytic cleavage of 125-kDa pre-SREBP1 from the endoplasmic reticulum/Golgi apparatus and nuclear translocation of active 68-kDa SREBP1. This block in SREBP1's posttranslational processing impaired transcriptional activation of SREBP1 response elements in the proximal human Cav1 promoter. Cav1 was also down-regulated in esophagi from C57BL/6 mice on a diet enriched with 1% (wt/wt) chenodeoxycholic acid. Mice deficient for Cav1 or the nuclear bile acid receptor farnesoid X receptor showed hyperplasia and hyperkeratosis of the basal cell layer of esophageal epithelia, respectively. These data indicate that bile acid-mediated down-regulation of Cav1 marks early changes in the squamous epithelium, which may contribute to onset of Barrett esophagus

  1. Caveolin-1–mediated Suppression of Cyclooxygenase-2 via a β-catenin-Tcf/Lef–dependent Transcriptional Mechanism Reduced Prostaglandin E2 Production and Survivin Expression

    PubMed Central

    Rodriguez, Diego A.; Tapia, Julio C.; Fernandez, Jaime G.; Torres, Vicente A.; Muñoz, Nicolas; Galleguillos, Daniela; Leyton, Lisette

    2009-01-01

    Augmented expression of cyclooxygenase-2 (COX-2) and enhanced production of prostaglandin E2 (PGE2) are associated with increased tumor cell survival and malignancy. Caveolin-1 is a scaffold protein that has been proposed to function as a tumor suppressor in human cancer cells, although mechanisms underlying this ability remain controversial. Intriguingly, the possibility that caveolin-1 regulates the expression of COX-2 has not been explored. Here we show that augmented caveolin-1 expression in cells with low basal levels of this protein, such as human colon cancer (HT29, DLD-1), breast cancer (ZR75), and embryonic kidney (HEK293T) cells reduced COX-2 mRNA and protein levels and β-catenin-Tcf/Lef and COX-2 gene reporter activity, as well as the production of PGE2 and cell proliferation. Moreover, COX-2 overexpression or PGE2 supplementation increased levels of the inhibitor of apoptosis protein survivin by a transcriptional mechanism, as determined by PCR analysis, survivin gene reporter assays and Western blotting. Furthermore, addition of PGE2 to the medium prevented effects attributed to caveolin-1–mediated inhibition of β-catenin-Tcf/Lef–dependent transcription. Finally, PGE2 reduced the coimmunoprecipitation of caveolin-1 with β-catenin and their colocalization at the plasma membrane. Thus, by reducing COX-2 expression, caveolin-1 interrupts a feedback amplification loop involving PGE2-induced signaling events linked to β-catenin/Tcf/Lef–dependent transcription of tumor survival genes including cox-2 itself and survivin. PMID:19244345

  2. ∆Np73beta induces caveolin-1 in human non-small cell lung cancer cell line H1299.

    PubMed

    Caiola, Elisa; Marrazzo, Eleonora; Alesci, Simona; Broggini, Massimo; Marabese, Mirko

    2016-02-01

    Caveolins have recently attracted attention for their possible involvement in signal transduction. Their role in cancer is debated, being reported both a suppressive and oncogenic role in different experimental conditions. Caveolin-1 is regulated by the tumor suppressor p53 which is able to bind its promoter and activate transcription. We had previous evidences indicating that a specific p73 isoform, namely ∆Np73β, when overexpressed in NCI-H1299 induced growth arrest and cell death. By gene expression analysis in cell transiently overexpressed with ∆Np73β, a strong induction of caveolin-1 was found. Caveolin was induced both at mRNA and protein level, and we characterised the promoter sequence of the gene encoding for caveolin-1 and found that the promoter region containing the putative p53 (and hence p73) binding sequence was responsive to ∆Np73β, but not to ∆Np73α and ∆Np73γ which do not induce growth arrest as ∆Np73β does. A reduction in cell adhesion was observed in ∆Np73β overexpressing cells, again supporting a possible role of caveolins in determining these effects. By using specific siRNA directed against human caveolin-1, we could not however antagonize the effects induced by ∆Np73β. Although caveolin-1 represents one of the genes whose expression is strongly activated by ∆Np73β, we could not define a role of caveolin-1 as a mediator of ∆Np73β associated growth arrest. It could well be that the expression of caveolin-1 is able to mediate other activities of ∆Np73β, and studies are in progress to determine whether its expression is mainly associated to metastatic spread.

  3. The Ankrd13 Family of Ubiquitin-interacting Motif-bearing Proteins Regulates Valosin-containing Protein/p97 Protein-mediated Lysosomal Trafficking of Caveolin 1*

    PubMed Central

    Burana, Daocharad; Yoshihara, Hidehito; Tanno, Hidetaka; Yamamoto, Akitsugu; Saeki, Yasushi; Tanaka, Keiji; Komada, Masayuki

    2016-01-01

    Caveolin 1 (Cav-1) is an oligomeric protein that forms flask-shaped, lipid-rich pits, termed caveolae, on the plasma membrane. Cav-1 is targeted for lysosomal degradation in ubiquitination- and valosin-containing protein (VCP)-dependent manners. VCP, an ATPase associated with diverse cellular activities that remodels or segregates ubiquitinated protein complexes, has been proposed to disassemble Cav-1 oligomers on the endosomal membrane, facilitating the trafficking of Cav-1 to the lysosome. Genetic mutations in VCP compromise the lysosomal trafficking of Cav-1, leading to a disease called inclusion body myopathy with Paget disease of bone and/or frontotemporal dementia (IBMPFD). Here we identified the Ankrd13 family of ubiquitin-interacting motif (UIM)-containing proteins as novel VCP-interacting molecules on the endosome. Ankrd13 proteins formed a ternary complex with VCP and Cav-1 and exhibited high binding affinity for ubiquitinated Cav-1 oligomers in an UIM-dependent manner. Mass spectrometric analyses revealed that Cav-1 undergoes Lys-63-linked polyubiquitination, which serves as a lysosomal trafficking signal, and that the UIMs of Ankrd13 proteins bind preferentially to this ubiquitin chain type. The overexpression of Ankrd13 caused enlarged hollow late endosomes, which was reminiscent of the phenotype of the VCP mutations in IBMPFD. Overexpression of Ankrd13 proteins also stabilized ubiquitinated Cav-1 oligomers on the limiting membrane of enlarged endosomes. The interaction with Ankrd13 was abrogated in IMBPFD-associated VCP mutants. Collectively, our results suggest that Ankrd13 proteins cooperate with VCP to regulate the lysosomal trafficking of ubiquitinated Cav-1. PMID:26797118

  4. The Ankrd13 Family of Ubiquitin-interacting Motif-bearing Proteins Regulates Valosin-containing Protein/p97 Protein-mediated Lysosomal Trafficking of Caveolin 1.

    PubMed

    Burana, Daocharad; Yoshihara, Hidehito; Tanno, Hidetaka; Yamamoto, Akitsugu; Saeki, Yasushi; Tanaka, Keiji; Komada, Masayuki

    2016-03-18

    Caveolin 1 (Cav-1) is an oligomeric protein that forms flask-shaped, lipid-rich pits, termed caveolae, on the plasma membrane. Cav-1 is targeted for lysosomal degradation in ubiquitination- and valosin-containing protein (VCP)-dependent manners. VCP, an ATPase associated with diverse cellular activities that remodels or segregates ubiquitinated protein complexes, has been proposed to disassemble Cav-1 oligomers on the endosomal membrane, facilitating the trafficking of Cav-1 to the lysosome. Genetic mutations in VCP compromise the lysosomal trafficking of Cav-1, leading to a disease called inclusion body myopathy with Paget disease of bone and/or frontotemporal dementia (IBMPFD). Here we identified the Ankrd13 family of ubiquitin-interacting motif (UIM)-containing proteins as novel VCP-interacting molecules on the endosome. Ankrd13 proteins formed a ternary complex with VCP and Cav-1 and exhibited high binding affinity for ubiquitinated Cav-1 oligomers in an UIM-dependent manner. Mass spectrometric analyses revealed that Cav-1 undergoes Lys-63-linked polyubiquitination, which serves as a lysosomal trafficking signal, and that the UIMs of Ankrd13 proteins bind preferentially to this ubiquitin chain type. The overexpression of Ankrd13 caused enlarged hollow late endosomes, which was reminiscent of the phenotype of the VCP mutations in IBMPFD. Overexpression of Ankrd13 proteins also stabilized ubiquitinated Cav-1 oligomers on the limiting membrane of enlarged endosomes. The interaction with Ankrd13 was abrogated in IMBPFD-associated VCP mutants. Collectively, our results suggest that Ankrd13 proteins cooperate with VCP to regulate the lysosomal trafficking of ubiquitinated Cav-1. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. DNA methylation profiling identifies PTRF/Cavin-1 as a novel tumor suppressor in Ewing sarcoma when co-expressed with caveolin-1.

    PubMed

    Huertas-Martínez, Juan; Court, Franck; Rello-Varona, Santiago; Herrero-Martín, David; Almacellas-Rabaiget, Olga; Sáinz-Jaspeado, Miguel; Garcia-Monclús, Silvia; Lagares-Tena, Laura; Buj, Raquel; Hontecillas-Prieto, Lourdes; Sastre, Ana; Azorin, Daniel; Sanjuan, Xavier; López-Alemany, Roser; Moran, Sebastian; Roma, Josep; Gallego, Soledad; Mora, Jaume; García Del Muro, Xavier; Giangrande, Paloma H; Peinado, Miquel A; Alonso, Javier; de Alava, Enrique; Monk, Dave; Esteller, Manel; Tirado, Oscar M

    2017-02-01

    Epigenetic modifications have been shown to be important in developmental tumors as Ewing sarcoma. We profiled the DNA methylation status of 15 primary tumors, 7 cell lines, 10 healthy tissues and 4 human mesenchymal stem cells lines samples using the Infinium Human Methylation 450K. Differential methylation analysis between Ewing sarcoma and reference samples revealed 1166 hypermethylated and 864 hypomethylated CpG sites (Bonferroni p < 0.05, δ-β-value with absolute difference of >0.20) corresponding to 392 and 470 genes respectively. Gene Ontology analysis of genes differentially methylated in Ewing sarcoma samples showed a significant enrichment of developmental genes. Membrane and cell signal genes were also enriched, among those, 11 were related to caveola formation. We identified differential hypermethylation of CpGs located in the body and S-Shore of the PTRF gene in Ewing sarcoma that correlated with its repressed transcriptional state. Reintroduction of PTRF/Cavin-1 in Ewing sarcoma cells revealed a role of this protein as a tumor suppressor. Restoration of caveolae in the membrane of Ewing sarcoma cells, by exogenously reintroducing PTRF, disrupts the MDM2/p53 complex, which consequently results in the activation of p53 and the induction of apoptosis.

  6. Caveolin-1, a stress-related oncotarget, in drug resistance

    PubMed Central

    Wang, Zhiyu; Wang, Neng; Liu, Pengxi; Peng, Fu; Tang, Hailin; Chen, Qianjun; Xu, Rui; Dai, Yan; Lin, Yi; Xie, Xiaoming; Peng, Cheng; Situ, Honglin

    2015-01-01

    Caveolin-1 (Cav-1) is both a tumor suppressor and an oncoprotein. Cav-1 overexpression was frequently confirmed in advanced cancer stages and positively associated with ABC transporters, cancer stem cell populations, aerobic glycolysis activity and autophagy. Cav-1 was tied to various stresses including radiotherapy, fluid shear and oxidative stresses and ultraviolet exposure, and interacted with stress signals such as AMP-activated protein kinase. Finally, a Cav-1 fluctuation model during cancer development is provided and Cav-1 is suggested to be a stress signal and cytoprotective. Loss of Cav-1 may increase susceptibility to oncogenic events. However, research to explore the underlying molecular network between Cav-1 and stress signals is warranted. PMID:26431273

  7. Caveolin-1, a stress-related oncotarget, in drug resistance.

    PubMed

    Wang, Zhiyu; Wang, Neng; Liu, Pengxi; Peng, Fu; Tang, Hailin; Chen, Qianjun; Xu, Rui; Dai, Yan; Lin, Yi; Xie, Xiaoming; Peng, Cheng; Situ, Honglin

    2015-11-10

    Caveolin-1 (Cav-1) is both a tumor suppressor and an oncoprotein. Cav-1 overexpression was frequently confirmed in advanced cancer stages and positively associated with ABC transporters, cancer stem cell populations, aerobic glycolysis activity and autophagy. Cav-1 was tied to various stresses including radiotherapy, fluid shear and oxidative stresses and ultraviolet exposure, and interacted with stress signals such as AMP-activated protein kinase. Finally, a Cav-1 fluctuation model during cancer development is provided and Cav-1 is suggested to be a stress signal and cytoprotective. Loss of Cav-1 may increase susceptibility to oncogenic events. However, research to explore the underlying molecular network between Cav-1 and stress signals is warranted.

  8. Caveolin-1 expression is elevated in claudin-low mammary tumor cells.

    PubMed

    Thompson, Devan E; Siwicky, Megan D; Moorehead, Roger A

    2012-02-22

    Caveolin-1 is a scaffolding protein found in plasma membrane invaginations known as caveolae. Caveolin-1 can regulate a number of intracellular processes such as signal transduction, cholesterol metabolism and vesicular transport. With respect to breast cancer caveolin-1 has been observed in both tumor cells and stromal cells surrounding tumors however most of the recent research has focused on how the loss of caveolin-1 in the stromal cells surrounding the tumor alters the tumor microenvironment. Caveolin-1 expression was evaluated in (1) mammary tumors induced by the transgenic overexpression of the type I insulin-like growth factor receptor (IGF-IR), (2) mammary tumors that became independent of IGF-IR signalling and acquired a claudin-low genotype, (3) two murine mammary epithelial tumor cell lines and (4) two murine mammary claudin-low tumor cell lines. We found that mammary tumors induced by IGF-IR overexpression expressed low levels of caveolin-1 while mammary tumors that became independent of IGF-IR signalling expressed considerably higher levels of caveolin-1. Interestingly, pockets of caveolin-1 positive cells could be observed in some of the IGF-IR-induced mammary tumors and these caveolin-1 positive cells were associated with tumor cells that expressed basal cytokeratins (cytokeratins 5 and 14). This caveolin-1 expression pattern was maintained in the murine mammary tumor cell lines in that the epithelial mammary tumor cell lines expressed little or no caveolin-1 while the claudin-low cell lines expressed caveolin-1. Our model indicates that mammary tumor cells with epithelial characteristics lack caveolin-1 while mesenchymal tumor cells express caveolin-1 suggesting that caveolin-1 may serve as a marker of mammary tumor cells with mesenchymal characteristics such as claudin-low breast tumors.

  9. Caveolae and caveolin-1 in reptilian liver.

    PubMed

    Biazik, Joanna M; Jahn, Kristina A; Braet, Filip

    2011-08-01

    Caveolae are plasma-membrane invaginations that, by interacting with membrane-associated molecules such as endothelial nitric oxide synthase and tyrosine kinases, precisely regulate cell-signalling pathways responsible for cell structure and cell function. Indeed, there is widespread evidence that caveolae associate, structurally and functionally, with proteins, lipids and solutes to facilitate transcellular transport of these macromolecules. Caveolin-1, one of the family of membrane proteins that form caveolae, is most prominently expressed in endothelial cells of the vascular bed. Therefore, we have applied advanced electron microscopy as well as molecular biology techniques to study the presence of caveolae and caveolin-1 in the liver sinusoidal endothelium of reptiles. Reptiles are known to store excess lipid in the liver as an energy source for hibernation, and so offer a useful animal model in which to assess the structural and functional implications these subcellular compartments might have on liver sinusoidal endothelial transport. This study demonstrates that caveolae are indeed conserved across vertebrate species, whether mammalian or reptilian. It also presents as first novel data on the presence of caveolin-1-associated, tubular structures located within the cytoplasm of the lizard liver sinusoidal endothelium. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Palmitoylation of caveolin-1 in endothelial cells is post-translational but irreversible

    NASA Technical Reports Server (NTRS)

    Parat, M. O.; Fox, P. L.

    2001-01-01

    Caveolin-1 is a palmitoylated protein involved in assembly of signaling molecules in plasma membrane subdomains termed caveolae and in intracellular cholesterol transport. Three cysteine residues in the C terminus of caveolin-1 are subject to palmitoylation, which is not necessary for caveolar targeting of caveolin-1. Protein palmitoylation is a post-translational and reversible modification that may be regulated and that in turn may regulate conformation, membrane association, protein-protein interactions, and intracellular localization of the target protein. We have undertaken a detailed analysis of [(3)H]palmitate incorporation into caveolin-1 in aortic endothelial cells. The linkage of palmitate to caveolin-1 was hydroxylamine-sensitive and thus presumably a thioester bond. However, contrary to expectations, palmitate incorporation was blocked completely by the protein synthesis inhibitors cycloheximide and puromycin. In parallel experiments to show specificity, palmitoylation of aortic endothelial cell-specific nitric-oxide synthase was unaffected by these reagents. Inhibitors of protein trafficking, brefeldin A and monensin, blocked caveolin-1 palmitoylation, indicating that the modification was not cotranslational but rather required caveolin-1 transport from the endoplasmic reticulum and Golgi to the plasma membrane. In addition, immunophilin chaperones that form complexes with caveolin-1, i.e. FK506-binding protein 52, cyclophilin A, and cyclophilin 40, were not necessary for caveolin-1 palmitoylation because agents that bind immunophilins did not inhibit palmitoylation. Pulse-chase experiments showed that caveolin-1 palmitoylation is essentially irreversible because the release of [(3)H]palmitate was not significant even after 24 h. These results show that [(3)H]palmitate incorporation is limited to newly synthesized caveolin-1, not because incorporation only occurs during synthesis but because the continuous presence of palmitate on caveolin-1 prevents

  11. Sclareol inhibits cell proliferation and sensitizes cells to the antiproliferative effect of bortezomib via upregulating the tumor suppressor caveolin-1 in cervical cancer cells.

    PubMed

    Zhang, Ting; Wang, Ting; Cai, Peiling

    2017-06-01

    The anticancer effect of sclareol has long been reported, however, the exact mechanisms underlying the antitumorigenic effect of sclareol in cervical carcinoma remain to be fully elucidated. The present study analyzed cell proliferation and cell apoptosis by MTT and FITC‑Annexin V assays. The protein levels of caveolin‑1 (Cav‑1) and copper-zinc superoxide dismutase (SOD)1 were determined by western blotting, and the interaction of Cav1 and HSC70 was investigated by co‑immunoprecipitation experiments. The present study found that sclareol inhibited cell proliferation and induced apoptosis in HeLa cells. Two cancer‑associated proteins, Cav1 and SOD1 were identified as potential targets of sclareol in HeLa cells. The expression of Cav1 increased when the cells were treated with sclareol, and the protein level of SOD1 was negatively correlated with Cav1. The overexpression of Cav1 enhanced the sensitivity of the HeLa cells to sclareol treatment and downregulated the protein level of SOD1, which exhibited potential associations between Cav1 and SOD1. In addition, sclareol significantly sensitized several cancer cells to the anticancer effect of bortezomib by targeting Cav1 and SOD1. Taken together, the results of the present study demonstrated that sclareol inhibited tumor cell growth through the upregulation of Cav1, and provides a potential therapeutic target for human cancer.

  12. Caveolin-1 interacts with 5-HT2A serotonin receptors and profoundly modulates the signaling of selected Galphaq-coupled protein receptors.

    PubMed

    Bhatnagar, Anushree; Sheffler, Douglas J; Kroeze, Wesley K; Compton-Toth, BethAnn; Roth, Bryan L

    2004-08-13

    5-Hydroxytryptamine 2A (5-HT(2A)) serotonin receptors are important for a variety of functions including vascular smooth muscle contraction, platelet aggregation, and the modulation of perception, cognition, and emotion. In a search for 5-HT(2A) receptor-interacting proteins, we discovered that caveolin-1 (Cav-1), a scaffolding protein enriched in caveolae, complexes with 5-HT(2A) receptors in a number of cell types including C6 glioma cells, transfected HEK-293 cells, and rat brain synaptic membrane preparations. To address the functional significance of this interaction, we performed RNA interference-mediated knockdown of Cav-1 in C6 glioma cells, a cell type that endogenously expresses both 5-HT(2A) receptors and Cav-1. We discovered that the in vitro knockdown of Cav-1 in C6 glioma cells nearly abolished 5-HT(2A) receptor-mediated signal transduction as measured by calcium flux assays. RNA interference-mediated knockdown of Cav-1 also greatly attenuated endogenous Galpha(q)-coupled P2Y purinergic receptor-mediated signaling without altering the signaling of PAR-1 thrombin receptors. Cav-1 appeared to modulate 5-HT(2A) signaling by facilitating the interaction of 5-HT(2A) receptors with Galpha(q). These studies provide compelling evidence for a prominent role of Cav-1 in regulating the functional activity of not only 5-HT(2A) serotonin receptors but also selected Galpha(q)-coupled receptors.

  13. Cellular Prion Protein and Caveolin-1 Interaction in a Neuronal Cell Line Precedes Fyn/Erk 1/2 Signal Transduction

    PubMed Central

    Toni, Mattia; Spisni, Enzo; Griffoni, Cristiana; Santi, Spartaco; Riccio, Massimo; Lenaz, Patrizia; Tomasi, Vittorio

    2006-01-01

    It has been reported that cellular prion protein (PrPc) is enriched in caveolae or caveolae-like domains with caveolin-1 (Cav-1) participating to signal transduction events by Fyn kinase recruitment. By using the Glutathione-S-transferase (GST)-fusion proteins assay, we observed that PrPc strongly interacts in vitro with Cav-1. Thus, we ascertained the PrPc caveolar localization in a hypothalamic neuronal cell line (GN11), by confocal microscopy analysis, flotation on density gradient, and coimmunoprecipitation experiments. Following the anti-PrPc antibody-mediated stimulation of live GN11 cells, we observed that PrPc clustered on plasma membrane domains rich in Cav-1 in which Fyn kinase converged to be activated. After these events, a signaling cascade through p42/44 MAP kinase (Erk 1/2) was triggered, suggesting that following translocations from rafts to caveolae or caveolaelike domains PrPc could interact with Cav-1 and induce signal transduction events. PMID:17489019

  14. Interaction of Caveolin-1 with Ku70 Inhibits Bax-Mediated Apoptosis

    PubMed Central

    Zou, Huafei; Volonte, Daniela; Galbiati, Ferruccio

    2012-01-01

    Caveolin-1, the structural protein component of caveolae, acts as a scaffolding protein that functionally regulates signaling molecules. We show that knockdown of caveolin-1 protein expression enhances chemotherapeutic drug-induced apoptosis and inhibits long-term survival of colon cancer cells. In vitro studies demonstrate that caveolin-1 is a novel Ku70-binding protein, as shown by the binding of the scaffolding domain of caveolin-1 (amino acids 82–101) to the caveolin-binding domain (CBD) of Ku70 (amino acids 471–478). Cell culture data show that caveolin-1 binds Ku70 after treatment with chemotherapeutic drugs. Mechanistically, we found that binding of caveolin-1 to Ku70 inhibits the chemotherapeutic drug-induced release of Bax from Ku70, activation of Bax, translocation of Bax to mitochondria and apoptosis. Potentiation of apoptosis by knockdown of caveolin-1 protein expression is greatly reduced in the absence of Bax expression. Finally, we found that overexpression of wild type Ku70, but not a mutant form of Ku70 that cannot bind to caveolin-1 (Ku70 Φ→A), limits the chemotherapeutic drug-induced Ku70/Bax dissociation and apoptosis. Thus, caveolin-1 acts as an anti-apoptotic protein in colon cancer cells by binding to Ku70 and inhibiting Bax-dependent cell death. PMID:22745744

  15. The dengue virus non-structural protein 1 (NS1) is secreted from infected mosquito cells via a non-classical caveolin-1-dependent pathway.

    PubMed

    Alcalá, Ana C; Hernández-Bravo, Raiza; Medina, Fernando; Coll, David S; Zambrano, Jose L; Del Angel, Rosa M; Ludert, Juan E

    2017-08-01

    Dengue virus NS1 is a glycoprotein of 46-50 kDa that is conserved among flaviviruses, associates as a dimer to cell membranes and is secreted as a hexamer to the extracellular milieu. Recent evidence showed that NS1 is secreted efficiently from infected mosquito cells. To explore the secretory route of NS1 in mosquito cells, infected cells were treated with brefeldin A (BFA) and methyl-beta-cyclodextrin (MβCD). The results showed that MβCD, but not BFA, significantly reduced the release of NS1. Moreover, silencing the expression of caveolin-1 (CAV1; a key component of the caveolar system that transports cholesterol inside the cell), but not SAR1 (a GTPase that participates in the classical secretory pathway), also results in a significant reduction of the secretion of NS1. These results indicate that NS1 is released from mosquito cells via an unconventional secretory route that bypasses the Golgi complex, with the participation of CAV1. In agreement with this notion, differences were observed in the glycosylation status between secreted NS1 and E proteins. Classical mechanics and docking simulations suggested highly favoured interactions between the caveolin-binding domain present in NS1 and the scaffolding domain of CAV1. Finally, proximity ligation assays showed direct interaction between NS1 and CAV1 in infected mosquito cells. These findings are in line with the lipoprotein nature of secreted NS1 and provide new insights into the biology of NS1.

  16. Caveolin-1 knockout mice exhibit airway hyperreactivity

    PubMed Central

    Aravamudan, Bharathi; VanOosten, Sarah K.; Meuchel, Lucas W.; Vohra, Pawan; Thompson, Michael; Sieck, Gary C.; Prakash, Y. S.

    2012-01-01

    Caveolae are flask-shaped plasma membrane invaginations expressing the scaffolding caveolin proteins. Although caveolins have been found in endothelium and epithelium (where they regulate nitric oxide synthase activity), their role in smooth muscle is still under investigation. We and others have previously shown that caveolae of human airway smooth muscle (ASM), which express caveolin-1, contain Ca2+ and force regulatory proteins and are involved in mediating the effects of inflammatory cytokines such as TNF-α on intracellular Ca2+ concentration responses to agonist. Accordingly, we tested the hypothesis that in vivo, absence of caveolin-1 leads to reduced airway hyperresponsiveness, using a knockout (KO) (Cav1 KO) mouse and an ovalbumin-sensitized/challenged (OVA) model of allergic airway hyperresponsiveness. Surprisingly, airway responsiveness to methacholine, tested by use of a FlexiVent system, was increased in Cav1 KO control (CTL) as well as KO OVA mice, which could not be explained by a blunted immune response to OVA. In ASM of wild-type (WT) OVA mice, expression of caveolin-1, the caveolar adapter proteins cavins 1–3, and caveolae-associated Ca2+ and force regulatory proteins such as Orai1 and RhoA were all increased, effects absent in Cav1 KO CTL and OVA mice. However, as with WT OVA, both CTL and OVA Cav1 KO airways showed signs of enhanced remodeling, with high expression of proliferation markers and increased collagen. Separately, epithelial cells from airways of all three groups displayed lower endothelial but higher inducible nitric oxide synthase and arginase expression. Arginase activity was also increased in these three groups, and the inhibitor nor-NOHA (N-omega-nor-l-arginine) enhanced sensitivity of isolated tracheal rings to ACh, especially in Cav1 KO mice. On the basis of these data disproving our original hypothesis, we conclude that caveolin-1 has complex effects on ASM vs. epithelium, resulting in airway hyperreactivity in vivo mediated

  17. NS1619 regulates the expression of caveolin-1 protein in a time-dependent manner via ROS/PI3K/PKB/FoxO1 signaling pathway in brain tumor microvascular endothelial cells.

    PubMed

    Cai, Rui-Ping; Xue, Yi-Xue; Huang, Jian; Wang, Jin-Hui; Wang, Jia-Hong; Zhao, Song-Yan; Guan, Ting-Ting; Zhang, Zhou; Gu, Yan-Ting

    2016-10-15

    NS1619, a calcium-activated potassium channel (Kca channel) activator, can selectively and time-dependently accelerate the formation of transport vesicles in both the brain tumor capillary endothelium and tumor cells within 15min of treatment and then increase the permeability of the blood-brain tumor barrier (BTB). However, the mechanism involved is still under investigation. Using a rat brain glioma (C6) model, the expression of caveolin-1, FoxO1 and p-FoxO1 protein were examined at different time points after intracarotid infusion of NS1619 at a dose of 30μg/kg/min. Internalization of Cholera toxin subunit (CTB) labeled fluorescently was monitored by flow cytometry. The expression of caveolin-1 and FoxO1 protein at tumor microvessels was enhanced and caveolae-mediated CTB endocytosis was increased by NS1619 infusion for 15min. Compared with the 15min group, the expression of caveolin-1 protein was significantly decreased and the level of phosphorylation of FoxO1 was significantly increased in the NS1619 2h group. In addition, inhibitors of reactive oxygen species (ROS) or PI3K or PKB significantly attenuated the level of FoxO1 phosphorylation and also increased the expression of caveolin-1 protein in Human Brain Microvascular Endothelial Cells (HBMECs) cocultured with human glioma cells (U87) 2h after NS1619 treatment. This led to the conclusion that NS1619-mediated transport vesicle increase is, at least partly, related to the ROS/PI3K/PKB/FoxO1 signaling pathway. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Identification of Filamin as a Novel Ligand for Caveolin-1: Evidence for the Organization of Caveolin-1–associated Membrane Domains by the Actin Cytoskeleton

    PubMed Central

    Stahlhut, Martin; van Deurs, Bo

    2000-01-01

    Reports on the ultrastructure of cells as well as biochemical data have, for several years, been indicating a connection between caveolae and the actin cytoskeleton. Here, using a yeast two-hybrid approach, we have identified the F-actin cross-linking protein filamin as a ligand for the caveolae-associated protein caveolin-1. Binding of caveolin-1 to filamin involved the N-terminal region of caveolin-1 and the C terminus of filamin close to the filamin-dimerization domain. In in vitro binding assays, recombinant caveolin-1 bound to both nonmuscle and muscle filamin, indicating that the interaction might not be cell type specific. With the use of confocal microscopy, colocalization of caveolin-1 and filamin was observed in elongated patches at the plasma membrane. Remarkably, when stress fiber formation was induced with Rho-stimulating Escherichia coli cytotoxic necrotizing factor 1, the caveolin-1–positive structures became coaligned with stress fibers, indicating that there was a physical link connecting them. Immunogold double-labeling electron microscopy confirmed that caveolin-1–labeled racemose caveolae clusters were positive for filamin. The actin network, therefore, seems to be directly involved in the spatial organization of caveolin-1–associated membrane domains. PMID:10637311

  19. Regulation of Phagolysosomal Digestion by Caveolin-1 of the Retinal Pigment Epithelium Is Essential for Vision*

    PubMed Central

    Sethna, Saumil; Chamakkala, Tess; Gu, Xiaowu; Thompson, Timothy C.; Cao, Guangwen; Elliott, Michael H.; Finnemann, Silvia C.

    2016-01-01

    Caveolin-1 associates with the endo/lysosomal machinery of cells in culture, suggesting that it functions at these organelles independently of its contribution to cell surface caveolae. Here we explored mice lacking caveolin-1 specifically in the retinal pigment epithelium (RPE). The RPE supports neighboring photoreceptors via diurnal phagocytosis of spent photoreceptor outer segment fragments. Like mice lacking caveolin-1 globally, RPECAV1−/− mice developed a normal RPE and neural retina but showed reduced rod photoreceptor light responses, indicating that lack of caveolin-1 affects photoreceptor function in a non-cell-autonomous manner. RPECAV1−/− RPE in situ showed normal particle engulfment but delayed phagosome clearance and reversed diurnal profiles of levels and activities of lysosomal enzymes. Therefore, eliminating caveolin-1 specifically impairs phagolysosomal degradation by the RPE in vivo. Endogenous caveolin-1 was recruited to maturing phagolysosomes in RPE cells in culture. Consistent with these in vivo data, a moderate increase (to ∼2.5-fold) or decrease (by half) of caveolin-1 protein levels in RPE cells in culture was sufficient to accelerate or impair phagolysosomal digestion, respectively. A mutant form of caveolin-1 that fails to reach the cell surface augmented degradation like wild-type caveolin-1. Acidic lysosomal pH and increased protease activity are essential for digestion. We show that halving caveolin-1 protein levels significantly alkalinized lysosomal pH and decreased lysosomal enzyme activities. Taken together, our results reveal a novel role for intracellular caveolin-1 in modulating phagolysosomal function. Moreover, they show, for the first time, that organellar caveolin-1 significantly affects tissue functionality in vivo. PMID:26814131

  20. Caveolin-1 signaling in lung fibrosis.

    PubMed

    Tourkina, Elena; Hoffman, Stanley

    2012-01-01

    Caveolin-1 is a master regulator of several signaling cascades because it is able to bind to and thereby inhibit members of a variety of kinase families. While associated with caveolae and involved in their generation, caveolin-1 is also present at other sites. A variety of studies have suggested that caveolin-1 may be a useful therapeutic target in fibrotic diseases of the lung and other tissues because in these diseases a low level of caveolin-1 expression is associated with a high level of collagen expression and fibrosis. Reduced caveolin-1 expression is observed not only in the fibroblasts that secrete collagen, but also in epithelial cells and monocytes. This is intriguing because both epithelial cells and monocytes have been suggested to be precursors of fibroblasts. Likely downstream effects of loss of caveolin-1 in fibrosis include activation of TGF-β signaling and upregulation of CXCR4 in monocytes resulting in their enhanced migration into damaged tissue where its ligand CXCL12 is produced. Finally, it may be possible to target caveolin-1 in fibrotic diseases without the use of gene therapy. A caveolin-1 peptide (caveolin-1 scaffolding domain) has been identified that retains the function of the full-length molecule to inhibit kinases and that can be modified by addition of the Antennapedia internalization sequence to allow it to enter cells both in vitro and in vivo.

  1. Spatiotemporal expression of caveolin-1 and EMMPRIN during mouse tooth development.

    PubMed

    Shi, Lu; Li, Lingyun; Wang, Ding; Li, Shu; Chen, Zhi; An, Zhengwen

    2016-06-01

    Caveolin-1 is a scaffolding protein involved in the formation of cholesterol-rich caveolae lipid rafts within the plasma membrane and is capable of collecting signaling molecules into the caveolae and regulating their activity, including extracellular matrix metalloproteinase inducer (EMMPRIN). However, detailed expression patterns of caveolin-1 and EMMPRIN in the developing dental germ are largely unknown. The present study investigated the expression patterns of caveolin-1 and EMMPRIN in the developing mouse tooth germ by immunohistochemistry and real-time polymerase chain reaction. At the bud stage, caveolin-1 expression was initiated in the epithelium bud and mesenchymal cells, while EMMPRIN was weakly expressed at this stage. At the cap stage, caveolin-1 protein was located in the lingual part of the tooth germ; however, EMMPRIN protein was located in the labial part. From the bell stage to 2 days postnatal, caveolin-1 expression was detected in the ameloblasts and cervical loop area; with EMMPRIN expression in the ameloblasts and odontoblasts. Real-time polymerase chain reaction results showed that both caveolin-1 and EMMPRIN mRNA levels increased gradually with progression of developmental stages, and peaked at day two postnatal. The current finding suggests that both caveolin-1 and EMMPRIN take part in mouse tooth development, especially in the differentiation and organization of odontogenic tissues.

  2. A role for caveolin-1 in post-injury reactive neuronal plasticity.

    PubMed

    Gaudreault, Sophie B; Blain, Jean-François; Gratton, Jean-Philippe; Poirier, Judes

    2005-02-01

    Remodeling and plasticity in the adult brain require cholesterol redistribution and synthesis for the formation of new membrane components. Caveolin-1 is a cholesterol-binding membrane protein involved in cellular cholesterol transport and homeostasis. Evidence presented here demonstrates an up-regulation of caveolin-1 in the hippocampus, which was temporally correlated with an increase in synaptophysin during the reinnervation phase in a mouse model of hippocampal deafferentation. Using an in vitro model of neuronal reactive plasticity, we examined the effect of virally mediated overexpression of caveolin-1 on injured differentiated PC12 cells undergoing terminal remodeling. Three days post lesion, caveolin-1-overexpressing cells revealed increases in synaptophysin and GAP-43, two markers of neurite sprouting and synaptogenesis. Morphologically, caveolin-1-overexpressing cells showed a decrease in primary neurite outgrowth and branching as well as an increase in neurite density. Caveolin-1-overexpressing cells also revealed the presence of terminal swelling and beading along processes, consistent with a possible alteration of microtubules stability. Moreover, a focal enrichment of caveolin-1 immunofluorescence was observed at the bases of axonal and dendritic terminals of mouse primary hippocampal neurons. Altogether, these results indicate that caveolin-1 plays an active role in the regulation of injury-induced synaptic and terminal remodeling in the adult CNS.

  3. Caveolin-1 regulates contractility in differentiated vascular smooth muscle.

    PubMed

    Je, Hyun-Dong; Gallant, Cynthia; Leavis, Paul C; Morgan, Kathleen G

    2004-01-01

    Caveolin is a principal component of caveolar membranes. In the present study, we utilized a decoy peptide approach to define the degree of involvement of caveolin in PKC-dependent regulation of contractility of differentiated vascular smooth muscle. The primary isoform of caveolin in ferret aorta vascular smooth muscle is caveolin-1. Chemical loading of contractile vascular smooth muscle tissue with a synthetic caveolin-1 scaffolding domain peptide inhibited PKC-dependent increases in contractility induced by a phorbol ester or an alpha agonist. Peptide loading also resulted in a significant inhibition of phorbol ester-induced adducin Ser662 phosphorylation, an intracellular monitor of PKC kinase activity, ERK1/2 activation, and Ser789 phosphorylation of the actin binding protein caldesmon. alpha-Agonist-induced ERK1-1/2 activation was also inhibited by the caveolin-1 peptide. Scrambled peptide-loaded tissues or sham-loaded tissues were unaffected with respect to both contractility and signaling. Depolarization-induced activation of contraction was not affected by caveolin peptide loading. Similar results with respect to contractility and ERK1/2 activation during exposure to the phorbol ester or the alpha-agonist were obtained with the cholesterol-depleting agent methyl-beta-cyclodextrin. These results are consistent with a role for caveolin-1 in the coordination of signaling leading to the regulation of contractility of smooth muscle.

  4. Growth suppression of MCF-7 cancer cell-derived xenografts in nude mice by caveolin-1

    SciTech Connect

    Wu Ping; Wang Xiaohui; Li Fei; Qi Baoju; Zhu Hua; Liu Shuang; Cui Yeqing; Chen Jianwen

    2008-11-07

    Caveolin-1 is an essential structural constituent of caveolae membrane domains that has been implicated in mitogenic signaling and oncogenesis. However, the exact functional role of caveolin-1 still remains controversial. In this report, utilizing MCF-7 human breast adenocarcinoma cells stably transfected with caveolin-1 (MCF-7/cav-1 cells), we demonstrate that caveolin-1 expression dramatically inhibits invasion and migration of these cells. Importantly, in vivo experiments employing xenograft tumor models demonstrated that expression of caveolin-1 results in significant growth inhibition of breast tumors. Moreover, a dramatic delay in tumor progression was observed in MCF-7/cav-1 cells as compared with MCF-7 cells. Histological analysis of tumor sections demonstrated a marked decrease in the percentage of proliferating tumor cells (Ki-67 assay) along with an increase in apoptotic tumor cells (TUNEL assay) in MCF-7/cav-1-treated animals. Our current findings provide for the first time in vivo evidence that caveolin-1 can indeed function as a tumor suppressor in human breast adenocarcinoma derived from MCF-7 cells rather than as a tumor promoter.

  5. Caveolin-1 controls mitochondrial function through regulation of m-AAA mitochondrial protease

    PubMed Central

    Volonte, Daniela; Liu, Zhongmin; Shiva, Sruti; Galbiati, Ferruccio

    2016-01-01

    Mitochondrial proteases ensure mitochondrial integrity and function after oxidative stress by providing mitochondrial protein quality control. However, the molecular mechanisms that regulate this basic biological function in eukaryotic cells remain largely unknown. Caveolin-1 is a scaffolding protein involved in signal transduction. We find that AFG3L2, a m-AAA type of mitochondrial protease, is a novel caveolin-1-interacting protein in vitro. We show that oxidative stress promotes the translocation of both caveolin-1 and AFG3L2 to mitochondria, enhances the interaction of caveolin-1 with AFG3L2 in mitochondria and stimulates mitochondrial protease activity in wild-type fibroblasts. Localization of AFG3L2 to mitochondria after oxidative stress is inhibited in fibroblasts lacking caveolin-1, which results in impaired mitochondrial protein quality control, an oxidative phosphorylation to aerobic glycolysis switch and reduced ATP production. Mechanistically, we demonstrate that a lack of caveolin-1 does not alter either mitochondrial number or morphology but leads to the cytoplasmic and proteasome-dependent degradation of complexes I, III, IV and V upon oxidant stimulation. Restoration of mitochondrial respiratory chain complexes in caveolin-1 null fibroblasts reverts the enhanced glycolysis observed in these cells. Expression of a mutant form of AFG3L2, which has reduced affinity for caveolin-1, fails to localize to mitochondria and promotes degradation of complex IV after oxidative stress. Thus, caveolin-1 maintains mitochondrial integrity and function when cells are challenged with free radicals by promoting the mitochondrial localization of m-AAA protease and its quality control functions. PMID:27705926

  6. Oxidative stress inhibits caveolin-1 palmitoylation and trafficking in endothelial cells

    NASA Technical Reports Server (NTRS)

    Parat, Marie-Odile; Stachowicz, Rafal Z.; Fox, Paul L.

    2002-01-01

    During normal and pathological conditions, endothelial cells (ECs) are subjected to locally generated reactive oxygen species, produced by themselves or by other vessel wall cells. In excess these molecules cause oxidative injury to the cell but at moderate levels they might modulate intracellular signalling pathways. We have investigated the effect of oxidative stress on the palmitoylation and trafficking of caveolin-1 in bovine aortic ECs. Exogenous H2O2 did not alter the intracellular localization of caveolin-1 in ECs. However, metabolic labelling experiments showed that H2O2 inhibited the trafficking of newly synthesized caveolin-1 to membrane raft domains. Several mechanisms potentially responsible for this inhibition were examined. Impairment of caveolin-1 synthesis by H2O2 was not responsible for diminished trafficking. Similarly, the inhibition was independent of H2O2-induced caveolin-1 phosphorylation as shown by the markedly different concentration dependences. We tested the effect of H2O2 on palmitoylation of caveolin-1 by the incorporation of [3H]palmitic acid. Exposure of ECs to H2O2 markedly inhibited the palmitoylation of caveolin-1. Comparable inhibition was observed after treatment of cells with H2O2 delivered either as a bolus or by continuous delivery with glucose and glucose oxidase. Kinetic studies showed that H2O2 did not alter the rate of caveolin-1 depalmitoylation but instead decreased the 'on-rate' of palmitoylation. Together these results show for the first time the modulation of protein palmitoylation by oxidative stress, and suggest a cellular mechanism by which stress might influence caveolin-1-dependent cell activities such as the concentration of signalling proteins and cholesterol trafficking.

  7. Downregulation of caveolin-1 contributes to the synaptic plasticity deficit in the hippocampus of aged rats

    PubMed Central

    Liu, Yang; Liang, Zhanhua; Liu, Jing; Zou, Wei; Li, Xiaoyan; Wang, Yachen; An, Lijia

    2013-01-01

    Caveolin-1 is involved in the regulation of synaptic plasticity, but the relationship between its pression and cognitive function during aging remains controversial. To explore the relationship be-tween synaptic plasticity in the aging process and changes in learning and memory, we examined caveolin-1 expression in the hippocampus, cortex and cerebellum of rats at different ages. We also examined the relationship between the expression of caveolin-1 and synaptophysin, a marker of synaptic plasticity. Hippocampal caveolin-1 and synaptophysin expression in aged (22–24 month old) rats was significantly lower than that in young (1 month old) and adult (4 months old) rats. pression levels of both proteins were significantly greater in the cortex of aged rats than in that of young or adult rats, and levels were similar between the three age groups in the cerebellum. Linear regression analysis revealed that hippocampal expression of synaptophysin was associated with memory and learning abilities. Moreover, synaptophysin expression correlated positively with caveolin-1 expression in the hippocampus, cortex and cerebellum. These results confirm that caveolin-1 has a regulatory effect on synaptic plasticity, and suggest that the downregulation of hippocampal caveolin-1 expression causes a decrease in synaptic plasticity during physiological aging. PMID:25206583

  8. Caveolin-1 in tumor progression: the good, the bad and the ugly.

    PubMed

    Goetz, Jacky G; Lajoie, Patrick; Wiseman, Sam M; Nabi, Ivan R

    2008-12-01

    Caveolin-1 (Cav1) is a multifunctional scaffolding protein with multiple binding partners that is associated with cell surface caveolae and the regulation of lipid raft domains. Cav1 regulates multiple cancer-associated processes including cellular transformation, tumor growth, cell migration and metastasis, cell death and survival, multidrug resistance and angiogenesis. However, Cav1 has been reported to impact both positively and negatively on various aspects of tumor progression and while reported to function as a tumor suppressor, it has also been identified as a poor prognostic factor in various human cancers. In this review, we survey the functional roles of Cav1 in cancer and argue that Cav1 function is interdependent on tumor stage and the expression of molecular effectors that impact on its role during tumor progression.

  9. The less-often-traveled surface of stem cells: caveolin-1 and caveolae in stem cells, tissue repair and regeneration

    PubMed Central

    2013-01-01

    Stem cells are an important resource for tissue repair and regeneration. While a great deal of attention has focused on derivation and molecular regulation of stem cells, relatively little research has focused on how the subcellular structure and composition of the cell membrane influences stem cell activities such as proliferation, differentiation and homing. Caveolae are specialized membrane lipid rafts coated with caveolin scaffolding proteins, which can regulate cholesterol transport and the activity of cell signaling receptors and their downstream effectors. Caveolin-1 is involved in the regulation of many cellular processes, including growth, control of mitochondrial antioxidant levels, migration and senescence. These activities are of relevance to stem cell biology, and in this review evidence for caveolin-1 involvement in stem cell biology is summarized. Altered stem and progenitor cell populations in caveolin-1 null mice suggest that caveolin-1 can regulate stem cell proliferation, and in vitro studies with isolated stem cells suggest that caveolin-1 regulates stem cell differentiation. The available evidence leads us to hypothesize that caveolin-1 expression may stabilize the differentiated and undifferentiated stem cell phenotype, and transient downregulation of caveolin-1 expression may be required for transition between the two. Such regulation would probably be critical in regenerative applications of adult stem cells and during tissue regeneration. We also review here the temporal changes in caveolin-1 expression reported during tissue repair. Delayed muscle regeneration in transgenic mice overexpressing caveolin-1 as well as compromised cardiac, brain and liver tissue repair and delayed wound healing in caveolin-1 null mice suggest that caveolin-1 plays an important role in tissue repair, but that this role may be negative or positive depending on the tissue type and the nature of the repair process. Finally, we also discuss how caveolin-1

  10. Versatile Functions of Caveolin-1 in Aging-related Diseases

    PubMed Central

    Nguyen, Kim Cuc Thi

    2017-01-01

    Caveolin-1 (Cav-1) is a trans-membrane protein that is a major component of the caveolae structure on the plasma membrane. Cav-1 is involved in the regulation of various cellular processes, including cell growth, differentiation, endocytosis, and in particular it has been implied in cellular senescence. Here we review current knowledge about Cav-1 in cellular signaling and discuss the role of Cav-1 in aging-related diseases. PMID:28184336

  11. Growth of hormone-dependent MCF-7 breast cancer cells is promoted by constitutive caveolin-1 whose expression is lost in an EGF-R-mediated manner during development of tamoxifen resistance.

    PubMed

    Thomas, Nicholas B P; Hutcheson, Iain R; Campbell, Lee; Gee, Julia; Taylor, Kathryn M; Nicholson, Robert I; Gumbleton, Mark

    2010-02-01

    Caveolin-1 displays both tumour-suppressor and tumour-promoter properties in breast cancer. Using characterised preclinical cell models for the transition of oestrogen-sensitive (WT-MCF-7 cells) to a tamoxifen-resistant (TAM-R cells) phenotype we examined the role caveolin-1 in the development of hormone-resistant breast cancer. The WT-MCF-7 cells showed abundant expression of caveolin-1 which potentiated oestrogen-receptor (ERalpha) signalling and promoted cell growth despite caveolin-1 mediating inhibition of ERK signalling. In TAM-R cells caveolin-1 expression was negligible, repressed by EGF-R/ERK signalling. Pharmacological inhibition of EGFR/ERK in TAM-R cells restored caveolin-1 and also resulted in the emergence of pools of phosphorylated caveolin-1. WT-MCF-7 cells exposed to tamoxifen for upto 12 weeks displayed increased caveolin-1 (peaking by week 2) followed (after week 8) by a marked decrease as the cells progress to develop a stable tamoxifen-resistant phenotype. The targeted down-regulation (siRNA) of caveolin-1 in WT-MCF-7 cells reduced growth but did not affect their sensitivity to tamoxifen, suggesting loss of caveolin-1 alone is not sufficient to confer tamoxifen-resistance. Hyperactivation of EGFR/ERK is a feature of tamoxifen-resistant breast cancer cells, a principal driver of cell growth. Recombinant expression of caveolin-1 in TAM-R cells did not affect EGFR/ERK activity, potentially due to mislocalisation of caveolin-1 through hyperactivation of the mTOR pathway or altered caveolin-1 phosphorylation. This work defines a novel role for caveolin-1 with implications for the clinical course of breast cancer and identifies caveolin-1 as a potential drug target for the treatment of early oestrogen-dependent breast cancers. Further, the loss of caveolin-1 may have benefit as a molecular signature for tamoxifen resistance.

  12. Caveolin-1, cellular senescence and age-related diseases

    PubMed Central

    Zou, Huafei; Stoppani, Elena; Volonte, Daniela; Galbiati, Ferruccio

    2011-01-01

    According to the “free radical theory” of aging, normal aging occurs as the result of tissue damages inflicted by reactive oxygen species (ROS) when ROS production exceeds the antioxidant capacity of the cell. ROS induce cellular dysfunctions such as stress-induced premature senescence (SIPS), which is believed to contribute to normal organismal aging and play a role in age-related diseases. Consistent with this hypothesis, increased oxidative damage of DNA, proteins, and lipids have been reported in aged animals and senescent cells accumulate in vivo with advancing age. Caveolin-1 acts as a scaffolding protein that concentrates and functionally regulates signaling molecules. Recently, great progress has been made toward understanding of the role of caveolin-1 in stress-induced premature senescence. Data show that caveolin-mediated signaling may contribute to explain, at the molecular level, how oxidative stress promotes the deleterious effects of cellular senescence such as aging and age-related diseases. In this review, we discuss the cellular mechanisms and functions of caveolin-1 in the context of SIPS and their relevance to the biology of aging. PMID:22100852

  13. Altered Arachidonate Distribution in Macrophages from Caveolin-1 Null Mice Leading to Reduced Eicosanoid Synthesis*

    PubMed Central

    Astudillo, Alma M.; Pérez-Chacón, Gema; Meana, Clara; Balgoma, David; Pol, Albert; del Pozo, Miguel A.; Balboa, María A.; Balsinde, Jesús

    2011-01-01

    In this work we have studied the effect of caveolin-1 deficiency on the mechanisms that regulate free arachidonic acid (AA) availability. The results presented here demonstrate that macrophages from caveolin-1-deficient mice exhibit elevated fatty acid incorporation and remodeling and a constitutively increased CoA-independent transacylase activity. Mass spectrometry-based lipidomic analyses reveal stable alterations in the profile of AA distribution among phospholipids, manifested by reduced levels of AA in choline glycerophospholipids but elevated levels in ethanolamine glycerophospholipids and phosphatidylinositol. Furthermore, macrophages from caveolin-1 null mice show decreased AA mobilization and prostaglandin E2 and LTB4 production upon cell stimulation. Collectively, these results provide insight into the role of caveolin-1 in AA homeostasis and suggest an important role for this protein in the eicosanoid biosynthetic response. PMID:21852231

  14. Treadmill Exercise Promotes Neurogenesis in Ischemic Rat Brains via Caveolin-1/VEGF Signaling Pathways.

    PubMed

    Zhao, Yun; Pang, Qiongyi; Liu, Meixia; Pan, Jingzi; Xiang, Bingwu; Huang, Tingting; Tu, Fengxia; Liu, Chan; Chen, Xiang

    2017-02-01

    Using a model of middle cerebral artery occlusion (MCAO), we have previously demonstrated that treadmill exercise promotes angiogenesis in the ischemic penumbra through caveolin-1/VEGF signaling pathways. However, the function of caveolin-1/VEGF signaling in neurogenesis after MCAO has not been determined. In this study, we aimed to investigate the potential of treadmill exercise to promote neurogenesis after MCAO and whether caveolin-1/VEGF signaling pathways are involved. After MCAO, rats were subjected to a program of treadmill exercise. Daidzein (a specific inhibitor of caveolin-1 protein expression, 0.4 mg/kg) was used to confirm the effect of caveolin-1/VEGF signaling on exercise-mediated neurogenesis. We found that the total protein expression of both caveolin-1 and VEGF was increased by exercise and consistent with the improved neurological recovery, decreased infarct volumes and increased 5-bromo-2'-deoxyuridine (BrdU) in the ipsilateral Subventricular zone (SVZ), as well as increased numbers of BrdU/DCX and BrdU/Neun-positive cells in the peri-infarct region. Furthermore, we observed that the treadmill exercise-induced increased VEGF expression, improved neurological recovery, decreased infarct volumes, increased BrdU/DCX and BrdU/Neun-positive cells were significantly inhibited by the caveolin-1 inhibitor. Our results indicate that treadmill exercise improves neurological recovery in ischemic rats, possibly by enhancement of SVZ-derived neural stem cell (NSC) proliferation, migration and differentiation in the penumbra. Moreover, caveolin-1/VEGF signaling is involved in exercise-mediated NSC migration and neuronal differentiation.

  15. Caveolin-1 regulates shear stress-dependent activation of extracellular signal-regulated kinase

    NASA Technical Reports Server (NTRS)

    Park, H.; Go, Y. M.; Darji, R.; Choi, J. W.; Lisanti, M. P.; Maland, M. C.; Jo, H.

    2000-01-01

    Fluid shear stress activates a member of the mitogen-activated protein (MAP) kinase family, extracellular signal-regulated kinase (ERK), by mechanisms dependent on cholesterol in the plasma membrane in bovine aortic endothelial cells (BAEC). Caveolae are microdomains of the plasma membrane that are enriched with cholesterol, caveolin, and signaling molecules. We hypothesized that caveolin-1 regulates shear activation of ERK. Because caveolin-1 is not exposed to the outside, cells were minimally permeabilized by Triton X-100 (0.01%) to deliver a neutralizing, polyclonal caveolin-1 antibody (pCav-1) inside the cells. pCav-1 then bound to caveolin-1 and inhibited shear activation of ERK but not c-Jun NH(2)-terminal kinase. Epitope mapping studies showed that pCav-1 binds to caveolin-1 at two regions (residues 1-21 and 61-101). When the recombinant proteins containing the epitopes fused to glutathione-S-transferase (GST-Cav(1-21) or GST-Cav(61-101)) were preincubated with pCav-1, only GST-Cav(61-101) reversed the inhibitory effect of the antibody on shear activation of ERK. Other antibodies, including m2234, which binds to caveolin-1 residues 1-21, had no effect on shear activation of ERK. Caveolin-1 residues 61-101 contain the scaffolding and oligomerization domains, suggesting that binding of pCav-1 to these regions likely disrupts the clustering of caveolin-1 or its interaction with signaling molecules involved in the shear-sensitive ERK pathway. We suggest that caveolae-like domains play a critical role in the mechanosensing and/or mechanosignal transduction of the ERK pathway.

  16. Caveolin-1 regulates shear stress-dependent activation of extracellular signal-regulated kinase

    NASA Technical Reports Server (NTRS)

    Park, H.; Go, Y. M.; Darji, R.; Choi, J. W.; Lisanti, M. P.; Maland, M. C.; Jo, H.

    2000-01-01

    Fluid shear stress activates a member of the mitogen-activated protein (MAP) kinase family, extracellular signal-regulated kinase (ERK), by mechanisms dependent on cholesterol in the plasma membrane in bovine aortic endothelial cells (BAEC). Caveolae are microdomains of the plasma membrane that are enriched with cholesterol, caveolin, and signaling molecules. We hypothesized that caveolin-1 regulates shear activation of ERK. Because caveolin-1 is not exposed to the outside, cells were minimally permeabilized by Triton X-100 (0.01%) to deliver a neutralizing, polyclonal caveolin-1 antibody (pCav-1) inside the cells. pCav-1 then bound to caveolin-1 and inhibited shear activation of ERK but not c-Jun NH(2)-terminal kinase. Epitope mapping studies showed that pCav-1 binds to caveolin-1 at two regions (residues 1-21 and 61-101). When the recombinant proteins containing the epitopes fused to glutathione-S-transferase (GST-Cav(1-21) or GST-Cav(61-101)) were preincubated with pCav-1, only GST-Cav(61-101) reversed the inhibitory effect of the antibody on shear activation of ERK. Other antibodies, including m2234, which binds to caveolin-1 residues 1-21, had no effect on shear activation of ERK. Caveolin-1 residues 61-101 contain the scaffolding and oligomerization domains, suggesting that binding of pCav-1 to these regions likely disrupts the clustering of caveolin-1 or its interaction with signaling molecules involved in the shear-sensitive ERK pathway. We suggest that caveolae-like domains play a critical role in the mechanosensing and/or mechanosignal transduction of the ERK pathway.

  17. Expression of caveolin-1 in the early phase of beta-TCP implanted in dog mandible.

    PubMed

    Chou, Cherng-Tzeh; Bhawal, Ujjal K; Watanabe, Nobuyuki; Kuboyama, Noboru; Chang, Wei-Jen; Lee, Sheng-Yang; Abiko, Yoshimitsu

    2013-07-01

    Caveolin is an essential and signature protein of caveolae. Caveolin-1 participates in signal transduction processes by acting as a scaffolding protein that concentrates, organizes and functional regulates signalling molecules within caveolar membranes. Beta-tricalcium phosphate (β-TCP) has been widely used for scaffold in tissue engineering due to its high biodegradability, osteoconductivity, easy manipulation, and lack of histotoxicity. To better understand the role of caveolin-1 in bone homeostasis and response to β-TCP scaffold, β-TCP was implanted into the dog mandible defects in beagle dogs, and gene expression profiles were examined focused on the molecular components involved in caveolin-1 regulation. Here we showed the quantitative imageology analysis characterized using in vivo micro-computed tomography (CT) images at 4 and 7 days after β-TCP implanted in dog mandibles. The bone reformation by using the β-TCP scaffolds began within 4 days of surgery, and was healing well at 7 days after surgery. Higher mRNA level of caveolin-1 was observed in β-TCP-implanted Beagle dog mandibles compared with controls at day 4 and day 7 post-surgery. The enhancement of caveolin-1 by β-TCP was further confirmed by immunohistochemistry and immunofluorescence analysis. We further revealed increased Smad7 and Phospho Stat3 expression in β-TCP-implanted specimens. Taken together, these results suggest that the enhancement of caveolin-1 play an important role in accelerating bone formation by β-TCP.

  18. Analysis of the CAVEOLIN-1 gene at human chromosome 7q31.1 in primary tumours and tumour-derived cell lines.

    PubMed

    Hurlstone, A F; Reid, G; Reeves, J R; Fraser, J; Strathdee, G; Rahilly, M; Parkinson, E K; Black, D M

    1999-03-11

    We identified CAVEOLIN-1 as a candidate for a tumour suppressor gene mapping to human chromosome 7q31.1. A number of studies suggest that caveolin could function as a tumour suppressor. Expression of caveolin, and in turn the number of caveolae within a cell, are inversely correlated with the transforming ability of numerous oncoproteins, including H-ras, v-abl, and bcr-abl, and caveolin is a major transformation-dependent substrate of v-src. Heterologous expression of caveolin has been shown to abrogate anchorage-independent growth and induce apoptosis in transformed fibroblasts and also to suppress anchorage-independent growth in human mammary carcinoma cells. We have analysed the status and expression of the human CAVEOLIN-1 gene in primary tumours and tumour-derived cell lines. We found no evidence for mutation of CAVEOLIN-1 in human cancers. Additionally, we found that while the first two exons of CAVEOLIN-1 are associated with a CpG island, this is not methylated in either primary tumours or in tumour-derived cell lines in which Caveolin-1 expression is low or undetectable. The level of expression of Caveolin-1 does not correlate with loss of heterozygosity at the CAVEOLIN-1 locus in these same cell lines. Contrary to other published studies, we have shown that CAVEOLIN-1 is not expressed in normal breast ductal epithelial cells in vivo. CAVEOLIN-1 is however highly expressed in breast myoepithelial cells and its expression is retained in tumours derived from breast myoepithelium. Together our data refute a role for CAVEOLIN-1 as a breast tumour suppressor gene in vivo.

  19. Effect of alteration of caveolin-1 expression on doxorubicin-induced apoptosis in H9c2 cardiac cells.

    PubMed

    Takaguri, Akira; Kamato, Maiko; Satoh, Yoshiaki; Ohtsuki, Kazuaki; Satoh, Kumi

    2015-09-01

    Doxorubicin is an anthracycline antibiotic widely used in cancer treatment. Although its antitumor efficacy appears to be dose dependent, its clinical use is greatly restricted by the development of cardiotoxicity associated with apoptosis. Although caveolin-1, the major structural protein in caveolae, can positively or negatively regulate apoptosis depending on the stimulus or cell types, the contribution of caveolin-1 to doxorubicin-induced apoptosis remains unknown. This study was performed to identify the regulatory role of caveolin-1 on doxorubicin-induced apoptosis in H9c2 cardiac cells using a genetic approach. Caveolin-1 knockdown with a short hairpin (sh) RNA adenovirus, but not overexpression of wild-type caveolin-1, resulted in a marked inhibition of doxorubicin-induced caspase-3 cleavage. However, caveolin-1 knockdown tended to protect against doxorubicin-induced decrease in cell viability, but it did not significantly reverse cell death induced by doxorubicin. Doxorubicin stimulated the phosphorylation of p38 and extracellular signal regulated kinase (ERK). Doxorubicin-induced caspase-3 cleavage was inhibited by U0126, a MEK inhibitor or SB203580, a p38 inhibitor. Caveolin-1 knockdown markedly inhibited doxorubicin-induced p-38 phosphorylation but not ERK-mediated p-53 phosphorylation in H9c2 cardiac cells. Our results suggest that reduced caveolin-1 expression plays an anti-apoptotic role in doxorubicin-induced apoptosis but that it is insufficient to prevent such an apoptosis in H9c2 cardiac cells.

  20. Status of caveolin-1 in various membrane domains of the bovine lens.

    PubMed

    Cenedella, Richard J; Sexton, Patricia S; Brako, Lawrence; Lo, Woo-Kuen; Jacob, Robert F

    2007-10-01

    Recent studies of the distribution and relative concentration of caveolin-1 in fractions of bovine lens epithelial and fiber cells have led to the novel concept that caveolin-1 may largely exist as a peripheral membrane protein in some cells. Caveolin-1 is typically viewed as a scaffolding protein for caveolae in plasma membrane. In this study, membrane from cultured bovine lens epithelial cells and bovine lens fiber cells were divided into urea soluble and insoluble fractions. Cytosolic lipid vesicles were also recovered from the lens epithelial cells. Lipid-raft domains were recovered from fiber cells following treatment with detergents and examined for caveolin and lipid content. Aliquots of all fractions were Western blotted for caveolin-1. Fluorescence microscopy and double immunofluorescence labeling were used to examine the distribution of caveolin-1 in cultured epithelial cells. Electron micrographs revealed an abundance of caveolae in plasma membrane of cultured lens epithelial cells. About 60% of the caveolin-1 in the epithelial-crude membrane was soluble in urea, a characteristic of peripheral membrane proteins. About 30% of the total was urea-insoluble membrane protein that likely supports the structure of caveolae. The remaining caveolin was part of cytosolic lipid vesicles. By contrast, most caveolin in the bovine lens fiber cell membrane was identified as intrinsic protein, being present at relatively low concentrations in caveolae-free lipid raft domains enriched in cholesterol and sphingomyelin. We estimate that these domains occupied 25-30% of the fiber cell membrane surface. Thus, the status of caveolin-1 in lens epithelial cells appears markedly different from that in fiber cells.

  1. Loss of caveolin-1 gene expression accelerates the development of dysplastic mammary lesions in tumor-prone transgenic mice.

    PubMed

    Williams, Terence M; Cheung, Michelle W-C; Park, David S; Razani, Babak; Cohen, Alex W; Muller, William J; Di Vizio, Dolores; Chopra, Neeru G; Pestell, Richard G; Lisanti, Michael P

    2003-03-01

    Caveolin-1 is the principal structural component of caveolae microdomains, which represent a subcompartment of the plasma membrane. Several independent lines of evidence support the notion that caveolin-1 functions as a suppressor of cell transformation. For example, the human CAV-1 gene maps to a suspected tumor suppressor locus (D7S522/7q31.1) that is frequently deleted in a number of carcinomas, including breast cancers. In addition, up to 16% of human breast cancers harbor a dominant-negative mutation, P132L, in the CAV-1 gene. Despite these genetic associations, the tumor suppressor role of caveolin-1 still remains controversial. To directly assess the in vivo transformation suppressor activity of the caveolin-1 gene, we interbred Cav-1 (-/-) null mice with tumor-prone transgenic mice (MMTV-PyMT) that normally develop multifocal dysplastic lesions throughout the entire mammary tree. Herein, we show that loss of caveolin-1 gene expression dramatically accelerates the development of these multifocal dysplastic mammary lesions. At 3 wk of age, loss of caveolin-1 resulted in an approximately twofold increase in the number of lesions (foci per gland; 3.3 +/- 1.0 vs. 7.0 +/- 1.2) and an approximately five- to sixfold increase in the total area occupied by these lesions. Similar results were obtained at 4 wk of age. However, complete loss of caveolin-1 was required to accelerate the appearance of these dysplastic mammary lesions, because Cav-1 (+/-) heterozygous mice did not show any increases in foci development. We also show that loss of caveolin-1 increases the extent and the histological grade of these mammary lesions and facilitates the development of papillary projections in the mammary ducts. Finally, we demonstrate that cyclin D1 expression levels are dramatically elevated in Cav-1 (-/-) null mammary lesions, consistent with the accelerated appearance and growth of these dysplastic foci. This is the first in vivo demonstration that caveolin-1 can function as

  2. Caveolin-1 mutants P132L and Y14F are dominant negative regulators of invasion, migration and aggregation in H1299 lung cancer cells

    SciTech Connect

    Shatz, Maria; Lustig, Gila; Reich, Reuven; Liscovitch, Mordechai

    2010-06-10

    Caveolin-1 is an essential protein constituent of caveolae. Accumulating evidence indicates that caveolin-1 may act as a positive regulator of cancer progression. In this study, we investigated the function of caveolin-1 in human lung cancer cells. Caveolin-1 knockdown inhibited cell proliferation and reduced focal adhesion kinase (Fak) phosphorylation. Matrix invasion and cell migration as well as expression and activity of matrix metalloproteases were attenuated following caveolin-1 RNAi-mediated knockdown or overexpression of Y14F and P132L mutants, demonstrating dominant-negative activity of these mutants. Time-lapse fluorescence microscopy revealed that caveolin-1 and its mutants P132L and Y14F are localized to the trailing edge of migrating cells during both random and directed cell movement, implying an active role of caveolin-1 in the migration process. Suppression of caveolin-1 function greatly elevated the percentage of H1299 cells exhibiting focal adhesions. In addition, cell aggregation was increased by wild type caveolin-1 and attenuated by both P132L and Y14F mutants. Overexpression of wild type caveolin-1 increased caveolae density, however, P132L and Y14F mutants did not affect caveolae formation, suggesting that in this respect that the mutants do not act in a dominant negative manner, and that effects of caveolin-1 on caveolae and cell invasion, migration, focal adhesion and aggregation, are separable. Our data provide novel mechanistic insights into the role of caveolin-1 in cell motility, invasiveness and aggregation, therefore, expanding our understanding of the tumor-promoting activities of caveolin-1 in advanced-stage cancer.

  3. Caveolin-1 mutants P132L and Y14F are dominant negative regulators of invasion, migration and aggregation in H1299 lung cancer cells.

    PubMed

    Shatz, Maria; Lustig, Gila; Reich, Reuven; Liscovitch, Mordechai

    2010-06-10

    Caveolin-1 is an essential protein constituent of caveolae. Accumulating evidence indicates that caveolin-1 may act as a positive regulator of cancer progression. In this study, we investigated the function of caveolin-1 in human lung cancer cells. Caveolin-1 knockdown inhibited cell proliferation and reduced focal adhesion kinase (Fak) phosphorylation. Matrix invasion and cell migration as well as expression and activity of matrix metalloproteases were attenuated following caveolin-1 RNAi-mediated knockdown or overexpression of Y14F and P132L mutants, demonstrating dominant-negative activity of these mutants. Time-lapse fluorescence microscopy revealed that caveolin-1 and its mutants P132L and Y14F are localized to the trailing edge of migrating cells during both random and directed cell movement, implying an active role of caveolin-1 in the migration process. Suppression of caveolin-1 function greatly elevated the percentage of H1299 cells exhibiting focal adhesions. In addition, cell aggregation was increased by wild type caveolin-1 and attenuated by both P132L and Y14F mutants. Overexpression of wild type caveolin-1 increased caveolae density, however, P132L and Y14F mutants did not affect caveolae formation, suggesting that in this respect that the mutants do not act in a dominant negative manner, and that effects of caveolin-1 on caveolae and cell invasion, migration, focal adhesion and aggregation, are separable. Our data provide novel mechanistic insights into the role of caveolin-1 in cell motility, invasiveness and aggregation, therefore, expanding our understanding of the tumor-promoting activities of caveolin-1 in advanced-stage cancer.

  4. Sequence and detailed organization of the human caveolin-1 and -2 genes located near the D7S522 locus (7q31.1). Methylation of a CpG island in the 5' promoter region of the caveolin-1 gene in human breast cancer cell lines.

    PubMed

    Engelman, J A; Zhang, X L; Lisanti, M P

    1999-04-09

    The CA microsatellite repeat marker, D7S522, is located at the center of a approximately 1000 kb smallest common deleted region that is lost in many forms of human cancer. It has been proposed that a putative tumor suppressor gene lies in close proximity to D7S522, within this smallest common deleted region. However, the genes located in proximity to D7S522 have remained elusive. Recently, we identified five independent BAC clones (approximately 100-200 kb) containing D7S522 and the human genes encoding caveolins 1 and 2. Here, we present the detailed organization of the caveolin locus and its relationship to D7S522, as deduced using a shot-gun sequencing approach. We derived two adjacent contigs for a total coverage of approximately 250 kb. Analysis of these contigs reveals that D7S522 is located approximately 67 kb upstream of the caveolin-2 gene and that the caveolin-2 gene is located approximately 19 kb upstream of the caveolin-1 gene, providing for the first time a detailed genetic map of this region. Further sequence analysis reveals many interesting features of the caveolin genes; these include the intron-exon boundaries and several previously unrecognized CA repeats that lie within or in close proximity to the caveolin genes. The first and second exons of both caveolin genes are embedded within CpG islands. These results suggest that regulation of caveolin gene expression may be controlled, in part, by methylation of these CpG regions. In support of this notion, we show here that the CGs in the 5' promoter region of the caveolin-1 gene are functionally methylated in two human breast cancer cell lines (MCF7 and T-47D) that fail to express the caveolin-1 protein. In contrast, the same CGs in cultured normal human mammary epithelial cells (NHMECs) are non-methylated and these cells express high levels of the caveolin-1 protein. Comparison of the human locus with the same locus in the pufferfish Fugu rubripes reveals that the overall organization of the

  5. Caveolin-1 Deficiency May Predispose African Americans to Systemic Sclerosis–Related Interstitial Lung Disease

    PubMed Central

    Reese, Charles; Perry, Beth; Heywood, Jonathan; Bonner, Michael; Visconti, Richard P.; Lee, Rebecca; Hatfield, Corey M.; Silver, Richard M.; Hoffman, Stanley; Tourkina, Elena

    2014-01-01

    Objective Interstitial lung disease (ILD) is the leading cause of death in patients with systemic sclerosis (SSc; scleroderma). Although SSc-related ILD is more common and severe in African Americans than in Caucasians, little is known about factors underlying this significant health disparity. The aim of this study was to examine the role that low expression of caveolin-1 might play in susceptibility to ILD among African Americans. Methods Assays of monocyte migration toward stromal cell–derived factor 1 (SDF-1) were performed using monocytes from Caucasian and African American healthy donors and patients with SSc. For fibrocyte differentiation studies, total peripheral blood mono-nuclear cells were incubated on fibronectin-coated plates. Protein expression was evaluated by immuno-histochemistry and Western blotting. Results Monocytes from healthy African American donors and those from patients with SSc had low caveolin-1 levels, enhanced migration toward the CXCR4 ligand SDF-1, and enhanced differentiation to fibrocytes. Enhanced migration and differentiation of monocytes from African Americans and patients with SSc appeared to be attributable to the lack of caveolin-1, because restoring caveolin-1 function using a caveolin-1 scaffolding domain peptide inhibited these processes. Although they differed from monocytes from Caucasians, monocytes from both African Americans and patients with SSc were not identical, because SSc monocytes showed major increases from baseline in ERK, JNK, p38, and Smad2/3 activation, while monocytes from African Americans showed only limited ERK activation and no activation of JNK, p38, or Smad2/3. In contrast, SDF-1 exposure caused no additional ERK activation in SSc monocytes but did cause significant additional activation in monocytes from African Americans. Conclusion African Americans may be predisposed to SSc-related ILD due to low baseline caveolin-1 levels in their monocytes, potentially affecting signaling, migration, and

  6. Caveolin-1 deficiency may predispose African Americans to systemic sclerosis-related interstitial lung disease.

    PubMed

    Reese, Charles; Perry, Beth; Heywood, Jonathan; Bonner, Michael; Visconti, Richard P; Lee, Rebecca; Hatfield, Corey M; Silver, Richard M; Hoffman, Stanley; Tourkina, Elena

    2014-07-01

    Interstitial lung disease (ILD) is the leading cause of death in patients with systemic sclerosis (SSc; scleroderma). Although SSc-related ILD is more common and severe in African Americans than in Caucasians, little is known about factors underlying this significant health disparity. The aim of this study was to examine the role that low expression of caveolin-1 might play in susceptibility to ILD among African Americans. Assays of monocyte migration toward stromal cell-derived factor 1 (SDF-1) were performed using monocytes from Caucasian and African American healthy donors and patients with SSc. For fibrocyte differentiation studies, total peripheral blood mononuclear cells were incubated on fibronectin-coated plates. Protein expression was evaluated by immunohistochemistry and Western blotting. Monocytes from healthy African American donors and those from patients with SSc had low caveolin-1 levels, enhanced migration toward the CXCR4 ligand SDF-1, and enhanced differentiation to fibrocytes. Enhanced migration and differentiation of monocytes from African Americans and patients with SSc appeared to be attributable to the lack of caveolin-1, because restoring caveolin-1 function using a caveolin-1 scaffolding domain peptide inhibited these processes. Although they differed from monocytes from Caucasians, monocytes from both African Americans and patients with SSc were not identical, because SSc monocytes showed major increases from baseline in ERK, JNK, p38, and Smad2/3 activation, while monocytes from African Americans showed only limited ERK activation and no activation of JNK, p38, or Smad2/3. In contrast, SDF-1 exposure caused no additional ERK activation in SSc monocytes but did cause significant additional activation in monocytes from African Americans. African Americans may be predisposed to SSc-related ILD due to low baseline caveolin-1 levels in their monocytes, potentially affecting signaling, migration, and fibrocyte differentiation. The monocytes of

  7. Caveolin-2 associates with intracellular chlamydial inclusions independently of caveolin-1.

    PubMed

    Webley, Wilmore C; Norkin, Leonard C; Stuart, Elizabeth S

    2004-07-22

    Lipid raft domains form in plasma membranes of eukaryotic cells by the tight packing of glycosphingolipids and cholesterol. Caveolae are invaginated structures that form in lipid raft domains when the protein caveolin-1 is expressed. The Chlamydiaceae are obligate intracellular bacterial pathogens that replicate entirely within inclusions that develop from the phagocytic vacuoles in which they enter. We recently found that host cell caveolin-1 is associated with the intracellular vacuoles and inclusions of some chlamydial strains and species, and that entry of those strains depends on intact lipid raft domains. Caveolin-2 is another member of the caveolin family of proteins that is present in caveolae, but of unknown function. We utilized a caveolin-1 negative/caveolin-2 positive FRT cell line and laser confocal immunofluorescence techniques to visualize the colocalization of caveolin-2 with the chlamydial inclusions. We show here that in infected HeLa cells, caveolin-2, as well as caveolin-1, colocalizes with inclusions of C. pneumoniae (Cp), C. caviae (GPIC), and C. trachomatis serovars E, F and K. In addition, caveolin-2 also associates with C. trachomatis serovars A, B and C, although caveolin-1 did not colocalize with these organisms. Moreover, caveolin-2 appears to be specifically, or indirectly, associated with the pathogens at the inclusion membranes. Using caveolin-1 deficient FRT cells, we show that although caveolin-2 normally is not transported out of the Golgi in the absence of caveolin-1, it nevertheless colocalizes with chlamydial inclusions in these cells. However, our results also show that caveolin-2 did not colocalize with UV-irradiated Chlamydia in FRT cells, suggesting that in these caveolin-1 negative cells, pathogen viability and very likely pathogen gene expression are necessary for the acquisition of caveolin-2 from the Golgi. Caveolin-2 associates with the chlamydial inclusion independently of caveolin-1. The function of caveolin-2, either

  8. Caveolin-2 associates with intracellular chlamydial inclusions independently of caveolin-1

    PubMed Central

    Webley, Wilmore C; Norkin, Leonard C; Stuart, Elizabeth S

    2004-01-01

    Background Lipid raft domains form in plasma membranes of eukaryotic cells by the tight packing of glycosphingolipids and cholesterol. Caveolae are invaginated structures that form in lipid raft domains when the protein caveolin-1 is expressed. The Chlamydiaceae are obligate intracellular bacterial pathogens that replicate entirely within inclusions that develop from the phagocytic vacuoles in which they enter. We recently found that host cell caveolin-1 is associated with the intracellular vacuoles and inclusions of some chlamydial strains and species, and that entry of those strains depends on intact lipid raft domains. Caveolin-2 is another member of the caveolin family of proteins that is present in caveolae, but of unknown function. Methods We utilized a caveolin-1 negative/caveolin-2 positive FRT cell line and laser confocal immunofluorescence techniques to visualize the colocalization of caveolin-2 with the chlamydial inclusions. Results We show here that in infected HeLa cells, caveolin-2, as well as caveolin-1, colocalizes with inclusions of C. pneumoniae (Cp), C. caviae (GPIC), and C. trachomatis serovars E, F and K. In addition, caveolin-2 also associates with C. trachomatis serovars A, B and C, although caveolin-1 did not colocalize with these organisms. Moreover, caveolin-2 appears to be specifically, or indirectly, associated with the pathogens at the inclusion membranes. Using caveolin-1 deficient FRT cells, we show that although caveolin-2 normally is not transported out of the Golgi in the absence of caveolin-1, it nevertheless colocalizes with chlamydial inclusions in these cells. However, our results also show that caveolin-2 did not colocalize with UV-irradiated Chlamydia in FRT cells, suggesting that in these caveolin-1 negative cells, pathogen viability and very likely pathogen gene expression are necessary for the acquisition of caveolin-2 from the Golgi. Conclusion Caveolin-2 associates with the chlamydial inclusion independently of caveolin

  9. Oxidative Stress-induced Inhibition of Sirt1 by Caveolin-1 Promotes p53-dependent Premature Senescence and Stimulates the Secretion of Interleukin 6 (IL-6)*

    PubMed Central

    Volonte, Daniela; Zou, Huafei; Bartholomew, Janine N.; Liu, Zhongmin; Morel, Penelope A.; Galbiati, Ferruccio

    2015-01-01

    Oxidative stress can induce premature cellular senescence. Senescent cells secrete various growth factors and cytokines, such as IL-6, that can signal to the tumor microenvironment and promote cancer cell growth. Sirtuin 1 (Sirt1) is a class III histone deacetylase that regulates a variety of physiological processes, including senescence. We found that caveolin-1, a structural protein component of caveolar membranes, is a direct binding partner of Sirt1, as shown by the binding of the scaffolding domain of caveolin-1 (amino acids 82–101) to the caveolin-binding domain of Sirt1 (amino acids 310–317). Our data show that oxidative stress promotes the sequestration of Sirt1 into caveolar membranes and the interaction of Sirt1 with caveolin-1, which lead to inhibition of Sirt1 activity. Reactive oxygen species stimulation promotes acetylation of p53 and premature senescence in wild-type but not caveolin-1 null mouse embryonic fibroblasts (MEFs). Either down-regulation of Sirt1 expression or re-expression of caveolin-1 in caveolin-1 null MEFs restores reactive oxygen species-induced acetylation of p53 and premature senescence. In addition, overexpression of caveolin-1 induces stress induced premature senescence in p53 wild-type but not p53 knockout MEFs. Phosphorylation of caveolin-1 on tyrosine 14 promotes the sequestration of Sirt1 into caveolar membranes and activates p53/senescence signaling. We also identified IL-6 as a caveolin-1-specific cytokine that is secreted by senescent fibroblasts following the caveolin-1-mediated inhibition of Sirt1. The caveolin-1-mediated secretion of IL-6 by senescent fibroblasts stimulates the growth of cancer cells. Therefore, by inhibiting Sirt1, caveolin-1 links free radicals to the activation of the p53/senescence pathway and the protumorigenic properties of IL-6. PMID:25512378

  10. Oxidative stress-induced inhibition of Sirt1 by caveolin-1 promotes p53-dependent premature senescence and stimulates the secretion of interleukin 6 (IL-6).

    PubMed

    Volonte, Daniela; Zou, Huafei; Bartholomew, Janine N; Liu, Zhongmin; Morel, Penelope A; Galbiati, Ferruccio

    2015-02-13

    Oxidative stress can induce premature cellular senescence. Senescent cells secrete various growth factors and cytokines, such as IL-6, that can signal to the tumor microenvironment and promote cancer cell growth. Sirtuin 1 (Sirt1) is a class III histone deacetylase that regulates a variety of physiological processes, including senescence. We found that caveolin-1, a structural protein component of caveolar membranes, is a direct binding partner of Sirt1, as shown by the binding of the scaffolding domain of caveolin-1 (amino acids 82-101) to the caveolin-binding domain of Sirt1 (amino acids 310-317). Our data show that oxidative stress promotes the sequestration of Sirt1 into caveolar membranes and the interaction of Sirt1 with caveolin-1, which lead to inhibition of Sirt1 activity. Reactive oxygen species stimulation promotes acetylation of p53 and premature senescence in wild-type but not caveolin-1 null mouse embryonic fibroblasts (MEFs). Either down-regulation of Sirt1 expression or re-expression of caveolin-1 in caveolin-1 null MEFs restores reactive oxygen species-induced acetylation of p53 and premature senescence. In addition, overexpression of caveolin-1 induces stress induced premature senescence in p53 wild-type but not p53 knockout MEFs. Phosphorylation of caveolin-1 on tyrosine 14 promotes the sequestration of Sirt1 into caveolar membranes and activates p53/senescence signaling. We also identified IL-6 as a caveolin-1-specific cytokine that is secreted by senescent fibroblasts following the caveolin-1-mediated inhibition of Sirt1. The caveolin-1-mediated secretion of IL-6 by senescent fibroblasts stimulates the growth of cancer cells. Therefore, by inhibiting Sirt1, caveolin-1 links free radicals to the activation of the p53/senescence pathway and the protumorigenic properties of IL-6.

  11. Cystic fibrosis transmembrane conductance regulator and caveolin-1 regulate epithelial cell internalization of Pseudomonas aeruginosa

    PubMed Central

    Bajmoczi, Milan; Gadjeva, Mihaela; Alper, Seth L.; Pier, Gerald B.; Golan, David E.

    2009-01-01

    Patients with cystic fibrosis (CF) exhibit defective innate immunity and are susceptible to chronic lung infection with Pseudomonas aeruginosa. To investigate the molecular bases for the hypersusceptibility of CF patients to P. aeruginosa, we used the IB3-1 cell line with two defective CF transmembrane conductance regulator (CFTR) genes (ΔF508/W1282X) to generate isogenic stable, clonal lung epithelial cells expressing wild-type (WT)-CFTR with an NH2-terminal green fluorescent protein (GFP) tag. GFP-CFTR exhibited posttranslational modification, subcellular localization, and anion transport function typical of WT-CFTR. P. aeruginosa internalization, a component of effective innate immunity, required functional CFTR and caveolin-1, as shown by: 1) direct correlation between GFP-CFTR expression levels and P. aeruginosa internalization; 2) enhanced P. aeruginosa internalization by aminoglycoside-induced read through of the CFTR W1282X allele in IB3-1 cells; 3) decreased P. aeruginosa internalization following siRNA knockdown of GFP-CFTR or caveolin-1; and 4) spatial association of P. aeruginosa with GFP-CFTR and caveolin-1 at the cell surface. P. aeruginosa internalization also required free lateral diffusion of GFP-CFTR, allowing for bacterial coclustering with GFP-CFTR and caveolin-1 at the plasma membrane. Thus efficient initiation of innate immunity to P. aeruginosa requires formation of an epithelial “internalization platform” involving both caveolin-1 and functional, laterally mobile CFTR. PMID:19386787

  12. Cystic fibrosis transmembrane conductance regulator and caveolin-1 regulate epithelial cell internalization of Pseudomonas aeruginosa.

    PubMed

    Bajmoczi, Milan; Gadjeva, Mihaela; Alper, Seth L; Pier, Gerald B; Golan, David E

    2009-08-01

    Patients with cystic fibrosis (CF) exhibit defective innate immunity and are susceptible to chronic lung infection with Pseudomonas aeruginosa. To investigate the molecular bases for the hypersusceptibility of CF patients to P. aeruginosa, we used the IB3-1 cell line with two defective CF transmembrane conductance regulator (CFTR) genes (DeltaF508/W1282X) to generate isogenic stable, clonal lung epithelial cells expressing wild-type (WT)-CFTR with an NH(2)-terminal green fluorescent protein (GFP) tag. GFP-CFTR exhibited posttranslational modification, subcellular localization, and anion transport function typical of WT-CFTR. P. aeruginosa internalization, a component of effective innate immunity, required functional CFTR and caveolin-1, as shown by: 1) direct correlation between GFP-CFTR expression levels and P. aeruginosa internalization; 2) enhanced P. aeruginosa internalization by aminoglycoside-induced read through of the CFTR W1282X allele in IB3-1 cells; 3) decreased P. aeruginosa internalization following siRNA knockdown of GFP-CFTR or caveolin-1; and 4) spatial association of P. aeruginosa with GFP-CFTR and caveolin-1 at the cell surface. P. aeruginosa internalization also required free lateral diffusion of GFP-CFTR, allowing for bacterial coclustering with GFP-CFTR and caveolin-1 at the plasma membrane. Thus efficient initiation of innate immunity to P. aeruginosa requires formation of an epithelial "internalization platform" involving both caveolin-1 and functional, laterally mobile CFTR.

  13. Caveolin-1 isoforms are encoded by distinct mRNAs. Identification Of mouse caveolin-1 mRNA variants caused by alternative transcription initiation and splicing.

    PubMed

    Kogo, H; Fujimoto, T

    2000-01-14

    By searching the EST database with the known cDNA sequence encoding alpha-caveolin-1 (full-length: FL), we found a variant having a hitherto unknown sequence in place of the first exon (5'-end variant: 5'V). The expression level of 5'V mRNA was equivalent to that of FL mRNA. The entire sequences of FL and 5'V mRNA were determined by 3'- and 5'-RACE analysis; their sizes were 2484 bp and 2533 bp, respectively, and the sequences were identical except for the region of the first exon. By Northern blotting, FL and 5'V mRNAs showed the same tissue distribution, and were intensely expressed in the lung, heart, and skeletal muscle. Analyzing the protein production from these mRNAs using green fluorescent protein as a tag, we found FL mRNA to produce the alpha-isoform predominantly, but to form little beta-isoform. The production of the beta-isoform from 5'V mRNA was also demonstrated. By sequence analysis of the first intron of the caveolin-1 gene, a TATA box was found at 28 bp upstream of the transcription initiation site for 5'V mRNA. This is the first demonstration of caveolin-1 mRNA variants generated by alternative transcription initiation, and it indicates that the two isoforms of caveolin-1 are produced from two distinct mRNAs.

  14. Rosiglitazone ameliorates diffuse axonal injury by reducing loss of tau and up-regulating caveolin-1 expression

    PubMed Central

    Zhao, Yong-lin; Song, Jin-ning; Ma, Xu-dong; Zhang, Bin-fei; Li, Dan-dong; Pang, Hong-gang

    2016-01-01

    Rosiglitazone up-regulates caveolin-1 levels and has neuroprotective effects in both chronic and acute brain injury. Therefore, we postulated that rosiglitazone may ameliorate diffuse axonal injury via its ability to up-regulate caveolin-1, inhibit expression of amyloid-beta precursor protein, and reduce the loss and abnormal phosphorylation of tau. In the present study, intraperitoneal injection of rosiglitazone significantly reduced the levels of amyloid-beta precursor protein and hyperphosphorylated tau (phosphorylated at Ser404(p-tau (S404)), and it increased the expression of total tau and caveolin-1 in the rat cortex. Our results show that rosiglitazone inhibits the expression of amyloid-beta precursor protein and lowers p-tau (S404) levels, and it reduces the loss of total tau, possibly by up-regulating caveolin-1. These actions of rosiglitazone may underlie its neuroprotective effects in the treatment of diffuse axonal injury. PMID:27482223

  15. Differential regulation of muscarinic M2 and M3 receptor signaling in gastrointestinal smooth muscle by caveolin-1.

    PubMed

    Bhattacharya, Sayak; Mahavadi, Sunila; Al-Shboul, Othman; Rajagopal, Senthilkumar; Grider, John R; Murthy, Karnam S

    2013-08-01

    Caveolae act as scaffolding proteins for several G protein-coupled receptor signaling molecules to regulate their activity. Caveolin-1, the predominant isoform in smooth muscle, drives the formation of caveolae. The precise role of caveolin-1 and caveolae as scaffolds for G protein-coupled receptor signaling and contraction in gastrointestinal muscle is unclear. Thus the aim of this study was to examine the role of caveolin-1 in the regulation of Gq- and Gi-coupled receptor signaling. RT-PCR, Western blot, and radioligand-binding studies demonstrated the selective expression of M2 and M3 receptors in gastric smooth muscle cells. Carbachol (CCh) stimulated phosphatidylinositol (PI) hydrolysis, Rho kinase and zipper-interacting protein (ZIP) kinase activity, induced myosin phosphatase 1 (MYPT1) phosphorylation (at Thr(696)) and 20-kDa myosin light chain (MLC20) phosphorylation (at Ser(19)) and muscle contraction, and inhibited cAMP formation. Stimulation of PI hydrolysis, Rho kinase, and ZIP kinase activity, phosphorylation of MYPT1 and MLC20, and muscle contraction in response to CCh were attenuated by methyl β-cyclodextrin (MβCD) or caveolin-1 small interfering RNA (siRNA). Similar inhibition of PI hydrolysis, Rho kinase, and ZIP kinase activity and muscle contraction in response to CCh and gastric emptying in vivo was obtained in caveolin-1-knockout mice compared with wild-type mice. Agonist-induced internalization of M2, but not M3, receptors was blocked by MβCD or caveolin-1 siRNA. Stimulation of PI hydrolysis, Rho kinase, and ZIP kinase activities in response to other Gq-coupled receptor agonists such as histamine and substance P was also attenuated by MβCD or caveolin-1 siRNA. Taken together, these results suggest that caveolin-1 facilitates signaling by Gq-coupled receptors and contributes to enhanced smooth muscle function.

  16. The different functions and clinical significances of caveolin-1 in human adenocarcinoma and squamous cell carcinoma

    PubMed Central

    Fu, Pin; Chen, Fuchun; Pan, Qi; Zhao, Xianda; Zhao, Chen; Cho, William Chi-Shing; Chen, Honglei

    2017-01-01

    Caveolin-1 (Cav-1), a major structural protein of caveolae, is an integral membrane protein which plays an important role in the progression of carcinoma. However, whether Cav-1 acts as a tumor promoter or a tumor suppressor still remains controversial. For example, the tumor-promoting function of Cav-1 has been found in renal cancer, prostate cancer, tongue squamous cell carcinoma (SCC), lung SCC and bladder SCC. In contrast, Cav-1 also plays an inhibitory role in esophagus adenocarcinoma, lung adenocarcinoma and cutaneous SCC. The role of Cav-1 is still controversial in thyroid cancer, hepatocellular carcinoma, gastric adenocarcinoma, colon adenocarcinoma, breast cancer, pancreas cancer, oral SCC, laryngeal SCC, head and neck SCC, esophageal SCC and cervical SCC. Besides, it has been reported that the loss of stromal Cav-1 might predict poor prognosis in breast cancer, gastric cancer, pancreas cancer, prostate cancer, oral SCC and esophageal SCC. However, the accumulation of stromal Cav-1 has been found to be promoted by the progression of tongue SCC. Taken together, Cav-1 seems playing a different role in different cancer subtypes even of the same organ, as well as acting differently in the same cancer subtype of different organs. Thus, we hereby explore the functions of Cav-1 in human adenocarcinoma and SCC from the perspective of clinical significances and pathogenesis. We envision that novel targets may come with the further investigation of Cav-1 in carcinogenesis. PMID:28243118

  17. Caveolin-1 Sensitivity of Excitatory Amino Acid Transporters EAAT1, EAAT2, EAAT3, and EAAT4.

    PubMed

    Abousaab, Abeer; Warsi, Jamshed; Elvira, Bernat; Lang, Florian

    2016-06-01

    Excitatory amino acid transporters EAAT1 (SLC1A3), EAAT2 (SLC1A2), EAAT3 (SLC1A1), and EAAT4 (SLC1A6) serve to clear L-glutamate from the synaptic cleft and are thus important for the limitation of neuronal excitation. EAAT3 has previously been shown to form complexes with caveolin-1, a major component of caveolae, which participate in the regulation of transport proteins. The present study explored the impact of caveolin-1 on electrogenic transport by excitatory amino acid transporter isoforms EAAT1-4. To this end cRNA encoding EAAT1, EAAT2, EAAT3, or EAAT4 was injected into Xenopus oocytes without or with additional injection of cRNA encoding caveolin-1. The L-glutamate (2 mM)-induced inward current (I Glu) was taken as a measure of glutamate transport. As a result, I Glu was observed in EAAT1-, EAAT2-, EAAT3-, or EAAT4-expressing oocytes but not in water-injected oocytes, and was significantly decreased by coexpression of caveolin-1. Caveolin-1 decreased significantly the maximal transport rate. Treatment of EAATs-expressing oocytes with brefeldin A (5 µM) was followed by a decrease in conductance, which was similar in oocytes expressing EAAT together with caveolin-1 as in oocytes expressing EAAT1-4 alone. Thus, caveolin-1 apparently does not accelerate transporter protein retrieval from the cell membrane. In conclusion, caveolin-1 is a powerful negative regulator of the excitatory glutamate transporters EAAT1, EAAT2, EAAT3, and EAAT4.

  18. Effect of protein deficiency on suppressor cells.

    PubMed Central

    Khorshidi, M; Mohagheghpour, N

    1979-01-01

    The effects of moderate protein deficiency on the in vitro response of spleen cells to phytohemagglutinin in A/Jax mice were studied. The response of spleen cells from protein-deficient mice to phytohemagglutinin was found to be enhanced as compared with that of cells from control animals. Since inadequate development or function of suppressor cells in the protein-deficient mice offered a possible explanation for the enhanced lymphoproliferative activity, cocultures of spleen cells from protein-deficient and control animals were tested for their responses to phytohemagglutinin. Suppression of [3H]thymidine incorporation was detected in coculture of 25% mitomycin-treated spleen cells from control animals and 75% spleen cells from protein-deficient mice. The suppressor (regulator) elements in control spleens were found to reside in the adherent cell population. PMID:313906

  19. Genomic organization and transcriptional analysis of the human genes coding for caveolin-1 and caveolin-2.

    PubMed

    Fra, A M; Pasqualetto, E; Mancini, M; Sitia, R

    2000-02-08

    Caveolin-1 and caveolin-2 are related proteins involved in the biogenesis of caveolae. The corresponding genes in humans (CAV and CAV2, respectively), have been mapped to a common locus in chromosome 7q31.1, and are possible candidates for the tumor suppressor gene postulated in this region. Here, we show that CAV and CAV2 are independent transcriptional units lying in the same orientation, with CAV2 centromeric and about 17kb upstream to CAV. The two genes have similar tissue expression patterns. Alternative termination/polyadenylation generates two CAV2 mRNAs. Multiple transcriptional start sites spanning 35bp upstream from the CAV2 ATG are detected by 5' RACE, consistent with a TATA-less promoter predicted by sequence analysis. The CAV2 promoter region contains two SRE-like boxes resembling those described in the CAV promoter and proposed to link transcription to intracellular cholesterol levels. However, exogenous sterols had only minor effects on CAV and CAV2 RNA levels in HeLa cells, suggesting that SREBPs are not sufficient to regulate caveolin transcription.

  20. Peroxisome Proliferator-Activated Receptor γ-Mediated Inhibition on Hypoxia-Triggered Store-Operated Calcium Entry. A Caveolin-1-Dependent Mechanism.

    PubMed

    Yang, Kai; Lu, Wenju; Jiang, Qian; Yun, Xin; Zhao, Mingming; Jiang, Haiyang; Wang, Jian

    2015-12-01

    Our previous publication demonstrated that peroxisome proliferator-activated receptor γ (PPARγ) inhibits the pathogenesis of chronic hypoxia (CH)-induced pulmonary hypertension by targeting store-operated calcium entry (SOCE) in rat distal pulmonary arterial smooth muscle cells (PASMCs). In this study, we aim to determine the role of a membrane scaffolding protein, caveolin-1, during the suppressive process of PPARγ on SOCE. Adult (6-8 weeks) male Wistar rats (200-250 g) were exposed to CH (10% O2) for 21 days to establish CH-induced pulmonary hypertension. Primary cultured rat distal PASMCs were applied for the molecular biological experiments. First, hypoxic exposure led to 2.5-fold and 1-fold increases of caveolin-1 protein expression in the distal pulmonary arteries and PASMCs, respectively. Second, effective knockdown of caveolin-1 significantly reduced hypoxia-induced SOCE for 58.2% and 41.5%, measured by Mn(2+) quenching and extracellular Ca(2+) restoration experiments, respectively. These results suggested that caveolin-1 acts as a crucial regulator of SOCE, and hypoxia-up-regulated caveolin-1 largely accounts for hypoxia-elevated SOCE in PASMCs. Then, by using a high-potency PPARγ agonist, GW1929, we detected that PPARγ activation inhibited SOCE and caveolin-1 protein for 62.5% and 59.8% under hypoxia, respectively, suggesting that caveolin-1 also acts as a key target during the suppressive process of PPARγ on SOCE in PASMCs. Moreover, by using effective small interfering RNAs against PPARγ and caveolin-1, and PPARγ antagonist, T0070907, we observed that PPARγ plays an inhibitory role on caveolin-1 protein by promoting its lysosomal degradation, without affecting the messenger RNA level. PPARγ inhibits SOCE, at least partially, by suppressing cellular caveolin-1 protein in PASMCs.

  1. Peroxisome Proliferator–Activated Receptor γ–Mediated Inhibition on Hypoxia-Triggered Store-Operated Calcium Entry. A Caveolin-1–Dependent Mechanism

    PubMed Central

    Yang, Kai; Lu, Wenju; Jiang, Qian; Yun, Xin; Zhao, Mingming; Jiang, Haiyang

    2015-01-01

    Our previous publication demonstrated that peroxisome proliferator–activated receptor γ (PPARγ) inhibits the pathogenesis of chronic hypoxia (CH)–induced pulmonary hypertension by targeting store-operated calcium entry (SOCE) in rat distal pulmonary arterial smooth muscle cells (PASMCs). In this study, we aim to determine the role of a membrane scaffolding protein, caveolin-1, during the suppressive process of PPARγ on SOCE. Adult (6–8 weeks) male Wistar rats (200–250 g) were exposed to CH (10% O2) for 21 days to establish CH-induced pulmonary hypertension. Primary cultured rat distal PASMCs were applied for the molecular biological experiments. First, hypoxic exposure led to 2.5-fold and 1-fold increases of caveolin-1 protein expression in the distal pulmonary arteries and PASMCs, respectively. Second, effective knockdown of caveolin-1 significantly reduced hypoxia-induced SOCE for 58.2% and 41.5%, measured by Mn2+ quenching and extracellular Ca2+ restoration experiments, respectively. These results suggested that caveolin-1 acts as a crucial regulator of SOCE, and hypoxia–up-regulated caveolin-1 largely accounts for hypoxia-elevated SOCE in PASMCs. Then, by using a high-potency PPARγ agonist, GW1929, we detected that PPARγ activation inhibited SOCE and caveolin-1 protein for 62.5% and 59.8% under hypoxia, respectively, suggesting that caveolin-1 also acts as a key target during the suppressive process of PPARγ on SOCE in PASMCs. Moreover, by using effective small interfering RNAs against PPARγ and caveolin-1, and PPARγ antagonist, T0070907, we observed that PPARγ plays an inhibitory role on caveolin-1 protein by promoting its lysosomal degradation, without affecting the messenger RNA level. PPARγ inhibits SOCE, at least partially, by suppressing cellular caveolin-1 protein in PASMCs. PMID:26020612

  2. Diet-induced hypercholesterolemia promotes androgen-independent prostate cancer metastasis via IQGAP1 and caveolin-1.

    PubMed

    Moon, Hyeongsun; Ruelcke, Jayde E; Choi, Eunju; Sharpe, Laura J; Nassar, Zeyad D; Bielefeldt-Ohmann, Helle; Parat, Marie-Odile; Shah, Anup; Francois, Mathias; Inder, Kerry L; Brown, Andrew J; Russell, Pamela J; Parton, Robert G; Hill, Michelle M

    2015-04-10

    Obesity and metabolic syndrome are associated with several cancers, however, the molecular mechanisms remain to be fully elucidated. Recent studies suggest that hypercholesterolemia increases intratumoral androgen signaling in prostate cancer, but it is unclear whether androgen-independent mechanisms also exist. Since hypercholesterolemia is associated with advanced, castrate-resistant prostate cancer, in this study, we aimed to determine whether and how hypercholesterolemia affects prostate cancer progression in the absence of androgen signaling. We demonstrate that diet-induced hypercholesterolemia promotes orthotopic xenograft PC-3 cell metastasis, concomitant with elevated expression of caveolin-1 and IQGAP1 in xenograft tumor tissues. In vitro cholesterol treatment of PC-3 cells stimulated migration and increased IQGAP1 and caveolin-1 protein level and localization to a detergent-resistant fraction. Down-regulation of caveolin-1 or IQGAP1 in PC-3 cells reduced migration and invasion in vitro, and hypercholesterolemia-induced metastasis in vivo. Double knock-down of caveolin-1 and IQGAP1 showed no additive effect, suggesting that caveolin-1 and IQGAP1 act via the same pathway. Taken together, our data show that hypercholesterolemia promotes prostate cancer metastasis independent of the androgen pathway, in part by increasing IQGAP1 and caveolin-1. These results have broader implications for managing metastasis of cancers in general as IQGAP1 and hypercholesterolemia are implicated in the progression of several cancers.

  3. Diet-induced hypercholesterolemia promotes androgen-independent prostate cancer metastasis via IQGAP1 and caveolin-1

    PubMed Central

    Moon, Hyeongsun; Ruelcke, Jayde E.; Choi, Eunju; Sharpe, Laura J.; Nassar, Zeyad D.; Bielefeldt-Ohmann, Helle; Parat, Marie-Odile; Shah, Anup; Francois, Mathias; Inder, Kerry L.; Brown, Andrew J.; Russell, Pamela J.; Parton, Robert G.; Hill, Michelle M.

    2015-01-01

    Obesity and metabolic syndrome are associated with several cancers, however, the molecular mechanisms remain to be fully elucidated. Recent studies suggest that hypercholesterolemia increases intratumoral androgen signaling in prostate cancer, but it is unclear whether androgen-independent mechanisms also exist. Since hypercholesterolemia is associated with advanced, castrate-resistant prostate cancer, in this study, we aimed to determine whether and how hypercholesterolemia affects prostate cancer progression in the absence of androgen signaling. We demonstrate that diet-induced hypercholesterolemia promotes orthotopic xenograft PC-3 cell metastasis, concomitant with elevated expression of caveolin-1 and IQGAP1 in xenograft tumor tissues. In vitro cholesterol treatment of PC-3 cells stimulated migration and increased IQGAP1 and caveolin-1 protein level and localization to a detergent-resistant fraction. Down-regulation of caveolin-1 or IQGAP1 in PC-3 cells reduced migration and invasion in vitro, and hypercholesterolemia-induced metastasis in vivo. Double knock-down of caveolin-1 and IQGAP1 showed no additive effect, suggesting that caveolin-1 and IQGAP1 act via the same pathway. Taken together, our data show that hypercholesterolemia promotes prostate cancer metastasis independent of the androgen pathway, in part by increasing IQGAP1 and caveolin-1. These results have broader implications for managing metastasis of cancers in general as IQGAP1 and hypercholesterolemia are implicated in the progression of several cancers. PMID:25924234

  4. Pulmonary hypertension and metabolic syndrome: Possible connection, PPARγ and Caveolin-1.

    PubMed

    Mathew, Rajamma

    2014-08-26

    A number of disparate diseases can lead to pulmonary hypertension (PH), a serious disorder with a high morbidity and mortality rate. Recent studies suggest that the associated metabolic dysregulation may be an important factor adversely impacting the prognosis of PH. Furthermore, metabolic syndrome is associated with vascular diseases including PH. Inflammation plays a significant role both in PH and metabolic syndrome. Adipose tissue modulates lipid and glucose metabolism, and also produces pro- and anti-inflammatory adipokines that modulate vascular function and angiogenesis, suggesting a close functional relationship between the adipose tissue and the vasculature. Both caveolin-1, a cell membrane scaffolding protein and peroxisome proliferator-activated receptor (PPAR) γ, a ligand-activated transcription factor are abundantly expressed in the endothelial cells and adipocytes. Both caveolin-1 and PPARγ modulate proliferative and anti-apoptotic pathways, cell migration, inflammation, vascular homeostasis, and participate in lipid transport, triacylglyceride synthesis and glucose metabolism. Caveolin-1 and PPARγ regulate the production of adipokines and in turn are modulated by them. This review article summarizes the roles and inter-relationships of caveolin-1, PPARγ and adipokines in PH and metabolic syndrome.

  5. Caveolin-1 mediated uptake via langerin restricts HIV-1 infection in human Langerhans cells.

    PubMed

    van den Berg, Linda M; Ribeiro, Carla M S; Zijlstra-Willems, Esther M; de Witte, Lot; Fluitsma, Donna; Tigchelaar, Wikky; Everts, Vincent; Geijtenbeek, Teunis B H

    2014-12-31

    Human Langerhans cells (LCs) reside in foreskin and vaginal mucosa and are the first immune cells to interact with HIV-1 during sexual transmission. LCs capture HIV-1 through the C-type lectin receptor langerin, which routes the virus into Birbeck granules (BGs), thereby preventing HIV-1 infection. BGs are langerin-positive organelles exclusively present in LCs, however, their origin and function are unknown. Here, we not only show that langerin and caveolin-1 co-localize at the cell membrane and in vesicles but also that BGs are langerin/caveolin-1-positive vesicles are linked to the lysosomal degradation pathway in LCs. Moreover, inhibition of caveolar endocytosis in primary LCs abrogated HIV-1 sequestering into langerin(+) caveolar structures. Notably, both inhibition of caveolar uptake and silencing of caveolar structure protein caveolin-1 resulted in increased HIV-1 integration and subsequent infection. In contrast, inhibition of clathrin-mediated endocytosis did not affect HIV-1 integration, even though HIV-1 uptake was decreased, suggesting that clathrin-mediated endocytosis is not involved in HIV-1 restriction in LCs. Thus, our data strongly indicate that BGs belong to the caveolar endocytosis pathway and that caveolin-1 mediated HIV-1 uptake is an intrinsic restriction mechanism present in human LCs that prevents HIV-1 infection. Harnessing this particular internalization pathway has the potential to facilitate strategies to combat HIV-1 transmission.

  6. Hypermethylation of the caveolin-1 gene promoter in prostate cancer.

    PubMed

    Cui, J; Rohr, L R; Swanson, G; Speights, V O; Maxwell, T; Brothman, A R

    2001-02-15

    Hypermethylation of CpG islands in the promoter regions of tumor suppressor genes is one mechanism of tumorigenesis. Caveolin-1 (Cav-1), a gene coding for the structural component of cellular caveolae, is involved in cell signaling and has been proposed to be a tumor suppressor gene in several malignancies. This gene maps to 7q31.1, a site known to be deleted in some prostate tumors. We chose to examine the methylation status of the promoter region of Cav-1 to determine whether this gene could function as a tumor suppressor in prostate cancer Genomic DNA from both tumor and normal prostate epithelial cells was obtained from paraffin-embedded prostate sections by laser capture microdissection (LCM). The methylation status of 24 CpG sites at the 5' promoter region of Cav-1 was analyzed by bisulfite-direct-sequencing after amplification by PCR using primers specific for bisulfate modified DNA. Immunohistochemistry staining with a cav-1-specific antibody was also performed to evaluate the expression of the gene Twenty of the 22 (90.9%) informative cases showed promoter hypermethylation in the tumor cell population when compared with adjacent normal prostate cells with an average Methylation Index (potential frequency of total possible methylated Cs) from tumor cells equal to 0.426 vs. 0.186 for normal cells (P = 0.001). While no association with Gleason grade was found, overall increased methylation correlated with PSA failure (P = 0.016), suggestive of clinical recurrence. Elevated immunoreactivity with a Cav-1 antibody was observed in tumor cells from 7 of 26 prostate samples tested; this was associated with a Gleason score but not correlated with PSA failure or Methylation Index CpG sites at the 5' promoter of Cav-1 are more methylated in tumor than in adjacent normal prostate cells. Hypermethylation of the Cav-1 promoter supports the notion that Cav-1 may function as a tumor suppressor gene in prostate cancer and evidence is presented suggesting that methylation

  7. Nitroglycerin Tolerance in Caveolin-1 Deficient Mice

    PubMed Central

    Mao, Mao; Varadarajan, Sudhahar; Fukai, Tohru; Bakhshi, Farnaz R.; Chernaya, Olga; Dudley, Samuel C.; Minshall, Richard D.; Bonini, Marcelo G.

    2014-01-01

    Nitrate tolerance developed after persistent nitroglycerin (GTN) exposure limits its clinical utility. Previously, we have shown that the vasodilatory action of GTN is dependent on endothelial nitric oxide synthase (eNOS/NOS3) activity. Caveolin-1 (Cav-1) is known to interact with NOS3 on the cytoplasmic side of cholesterol-enriched plasma membrane microdomains (caveolae) and to inhibit NOS3 activity. Loss of Cav-1 expression results in NOS3 hyperactivation and uncoupling, converting NOS3 into a source of superoxide radicals, peroxynitrite, and oxidative stress. Therefore, we hypothesized that nitrate tolerance induced by persistent GTN treatment results from NOS3 dysfunction and vascular toxicity. Exposure to GTN for 48–72 h resulted in nitrosation and depletion (>50%) of Cav-1, NOS3 uncoupling as measured by an increase in peroxynitrite production (>100%), and endothelial toxicity in cultured cells. In the Cav-1 deficient mice, NOS3 dysfunction was accompanied by GTN tolerance (>50% dilation inhibition at low GTN concentrations). In conclusion, GTN tolerance results from Cav-1 modification and depletion by GTN that causes persistent NOS3 activation and uncoupling, preventing it from participating in GTN-medicated vasodilation. PMID:25158065

  8. Caveolin-1-Autophagy Pathway Mediated Cardiomyocyte Hypertrophy Induced by Apelin-13.

    PubMed

    Wu, Di; Xie, Feng; Xiao, Ling; Feng, Fen; Huang, Shifang; He, Lu; Liu, Meiqing; Zhou, Qun; Li, Lanfang; Chen, Linxi

    2017-08-01

    Apelin, an endogenous ligand for apelin receptor (APJ), is reported to be involved in cardiomyocyte hypertrophy. In this study, we explored the mechanism of cardiomyocyte hypertrophy induced by apelin-13/APJ system. Left ventricular hypertrophy (LVH) rat model was established by constricting the abdominal aorta. Western blots were used for protein expression in LVH rats and cultured H9c2 cardiomyocytes. Transmission electron microscopy (TEM) was used to monitor morphological features of cells. In addition, the diameter and volume of H9c2 cells were detected by Scepter™ Handheld Automated Cell Counter. We found that the APJ was increased, but caveolin-1 was decreased in heart of LVH rats. In addition, caveolin-1 was suppressed by apelin-13, and this effect was reversed by APJ antagonist F13A in cultured H9c2 cardiomyocytes. Apelin-13 not only stimulated the formation of autophagolysosomes, autophagosome, and lysosomes but also increased the expression of autophagic markers Beclin-1 and LC3II/I. Besides, the increase of Beclin-1 and LC3 II/I was reversed by F13A or caveolin-1 overexpression and further enhanced by caveolin inhibitor. Furthermore, the cardiomyocyte hypertrophy index brain natriuretic peptide (BNP) induced by apelin-13 was blunt by F13A or autophagy inhibitor 3-methyladenine and further promoted by caveolin inhibitor. And caveolin-1 overexpression reduced the diameter and volume of H9c2 cells induced by apelin-13. Our study indicates that caveolin-1-autophagy pathway mediated cardiomyocyte hypertrophy induced by apelin-13/APJ system, which might provide a novel therapeutic target for cardiac hypertrophy disease.

  9. Transcriptional repression of Caveolin-1 (CAV1) gene expression by GATA-6 in bladder smooth muscle hypertrophy in mice and human beings.

    PubMed

    Boopathi, Ettickan; Gomes, Cristiano Mendes; Goldfarb, Robert; John, Mary; Srinivasan, Vittala Gopal; Alanzi, Jaber; Malkowicz, S Bruce; Kathuria, Hasmeena; Zderic, Stephen A; Wein, Alan J; Chacko, Samuel

    2011-05-01

    Hypertrophy occurs in urinary bladder wall smooth muscle (BSM) in men with partial bladder outlet obstruction (PBOO) caused by benign prostatic hyperplasia (BPH) and in animal models of PBOO. Hypertrophied BSM from the rabbit model exhibits down-regulation of caveolin-1, a structural and functional protein of caveolae that function as signaling platforms to mediate interaction between receptor proteins and adaptor and effector molecules to regulate signal generation, amplification, and diversification. Caveolin-1 expression is diminished in PBOO-induced BSM hypertrophy in mice and in men with BPH. The proximal promoter of the human and mouse caveolin-1 (CAV1) gene was characterized, and it was observed that the transcription factor GATA-6 binds this promoter, causing reduced expression of caveolin-1. Furthermore, caveolin-1 expression levels inversely correlate with the abundance of GATA-6 in BSM hypertrophy in mice and human beings. Silencing of GATA6 gene expression up-regulates caveolin-1 expression, whereas overexpression of GATA-6 protein sustains the transcriptional repression of caveolin-1 in bladder smooth muscle cells. Together, these data suggest that GATA-6 acts as a transcriptional repressor of CAV1 gene expression in PBOO-induced BSM hypertrophy in men and mice. GATA-6-induced transcriptional repression represents a new regulatory mechanism of CAV1 gene expression in pathologic BSM, and may serve as a target for new therapy for BPH-induced bladder dysfunction in aging men. Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  10. Transcriptional Repression of Caveolin-1 (CAV1) Gene Expression by GATA-6 in Bladder Smooth Muscle Hypertrophy in Mice and Human Beings

    PubMed Central

    Boopathi, Ettickan; Gomes, Cristiano Mendes; Goldfarb, Robert; John, Mary; Srinivasan, Vittala Gopal; Alanzi, Jaber; Malkowicz, S. Bruce; Kathuria, Hasmeena; Zderic, Stephen A.; Wein, Alan J.; Chacko, Samuel

    2011-01-01

    Hypertrophy occurs in urinary bladder wall smooth muscle (BSM) in men with partial bladder outlet obstruction (PBOO) caused by benign prostatic hyperplasia (BPH) and in animal models of PBOO. Hypertrophied BSM from the rabbit model exhibits down-regulation of caveolin-1, a structural and functional protein of caveolae that function as signaling platforms to mediate interaction between receptor proteins and adaptor and effector molecules to regulate signal generation, amplification, and diversification. Caveolin-1 expression is diminished in PBOO-induced BSM hypertrophy in mice and in men with BPH. The proximal promoter of the human and mouse caveolin-1 (CAV1) gene was characterized, and it was observed that the transcription factor GATA-6 binds this promoter, causing reduced expression of caveolin-1. Furthermore, caveolin-1 expression levels inversely correlate with the abundance of GATA-6 in BSM hypertrophy in mice and human beings. Silencing of GATA6 gene expression up-regulates caveolin-1 expression, whereas overexpression of GATA-6 protein sustains the transcriptional repression of caveolin-1 in bladder smooth muscle cells. Together, these data suggest that GATA-6 acts as a transcriptional repressor of CAV1 gene expression in PBOO-induced BSM hypertrophy in men and mice. GATA-6-induced transcriptional repression represents a new regulatory mechanism of CAV1 gene expression in pathologic BSM, and may serve as a target for new therapy for BPH-induced bladder dysfunction in aging men. PMID:21514437

  11. Caveolin-1 Expression and Membrane Cholesterol Content Modulate N-Type Calcium Channel Activity in NG108-15 Cells

    PubMed Central

    Toselli, M.; Biella, G.; Taglietti, V.; Cazzaniga, E.; Parenti, M.

    2005-01-01

    Caveolins are the main structural proteins of glycolipid/cholesterol-rich plasmalemmal invaginations, termed caveolae. In addition, caveolin-1 isoform takes part in membrane remodelling as it binds and transports newly synthesized cholesterol from endoplasmic reticulum to the plasma membrane. Caveolin-1 is expressed in many cell types, including hippocampal neurons, where an abundant SNAP25-caveolin-1 complex is detected after induction of persistent synaptic potentiation. To ascertain whether caveolin-1 influences neuronal voltage-gated Ca2+ channel basal activity, we stably expressed caveolin-1 into transfected neuroblastoma × glioma NG108-15 hybrid cells [cav1(+) clone] that lack endogenous caveolins but express N-type Ca2+ channels upon cAMP-induced neuronal differentiation. Whole-cell patch-clamp recordings of cav1(+) cells demonstrated that N-type current density was reduced in size by ∼70% without any significant change in the time course of activation and inactivation and voltage dependence. Moreover, the cav1(+) clone exhibited a significantly increased proportion of membrane cholesterol compared to wild-type NG108-15 cells. To gain insight into the mechanism underlying caveolin-1 lowering of N-current density, and more precisely to test whether this was indirectly caused by caveolin-1-induced enhancement of membrane cholesterol, we compared single N-type channel activities in cav1(+) clone and wild-type NG108-15 cells enriched with cholesterol after exposure to a methyl-β-cyclodextrin-cholesterol complex. A lower Ca2+ channel activity was recorded from cell-attached patches of both cell types, thus supporting the view that the increased proportion of membrane cholesterol is ultimately responsible for the effect. This is due to a reduction in the probability of channel opening caused by a significant decrease of channel mean open time and by an increase of the frequency of null sweeps. PMID:16040758

  12. Polychlorinated biphenyl-induced VCAM-1 expression is attenuated in aortic endothelial cells isolated from caveolin-1 deficient mice

    SciTech Connect

    Han, Sung Gu; Eum, Sung Yong; Toborek, Michal; Smart, Eric; Hennig, Bernhard

    2010-07-15

    Exposure to environmental contaminants, such as polychlorinated biphenyls (PCBs), is a risk factor for the development of cardiovascular diseases such as atherosclerosis. Vascular cell adhesion molecule-1 (VCAM-1) is a critical mediator for adhesion and uptake of monocytes across the endothelium in the early stages of atherosclerosis development. The upregulation of VCAM-1 by PCBs may be dependent on functional membrane domains called caveolae. Caveolae are particularly abundant in endothelial cell membranes and involved in trafficking and signal transduction. The objective of this study was to investigate the role of caveolae in PCB-induced endothelial cell dysfunction. Primary mouse aortic endothelial cells (MAECs) isolated from caveolin-1-deficient mice and background C57BL/6 mice were treated with coplanar PCBs, such as PCB77 and PCB126. In addition, siRNA gene silencing technique was used to knockdown caveolin-1 in porcine vascular endothelial cells. In MAECs with functional caveolae, VCAM-1 protein levels were increased after exposure to both coplanar PCBs, whereas expression levels of VCAM-1 were not significantly altered in cells deficient of caveolin-1. Furthermore, PCB-induced monocyte adhesion was attenuated in caveolin-1-deficient MAECs. Similarly, siRNA silencing of caveolin-1 in porcine endothelial cells confirmed the caveolin-1-dependent VCAM-1 expression. Treatment of cells with PCB77 and PCB126 resulted in phosphorylation of extracellular signal-regulated kinase-1/2 (ERK1/2), and pharmacological inhibition of ERK1/2 diminished the observed PCB-induced increase in monocyte adhesion. These findings suggest that coplanar PCBs induce adhesion molecule expression, such as VCAM-1, in endothelial cells, and that this response is regulated by caveolin-1 and functional caveolae. Our data demonstrate a critical role of functional caveolae in the activation and dysfunction of endothelial cells by coplanar PCBs.

  13. Increased caveolin-1 expression in Alzheimer's disease brain.

    PubMed

    Gaudreault, Sophie B; Dea, Doris; Poirier, Judes

    2004-07-01

    Increasing evidence suggests that cholesterol plays a central role in the pathophysiology of Alzheimer's disease (AD). Caveolin is a cholesterol-binding membrane protein involved in cellular cholesterol transport. We investigated the changes in the protein amount of hippocampal caveolin of autopsy-confirmed AD and aged-matched control subjects. Our results demonstrate that caveolin protein levels in the hippocampus and caveolin mRNA in the frontal cortex are up-regulated in AD by approximately two-fold, compared to control brains. These results suggest a relationship between caveolin-1 expression levels and a dysregulation of cholesterol homeostasis at the plasma membrane of brain cells. In support of this hypothesis, a significant increase in caveolin protein levels has also been observed in hippocampal tissue from ApoE-deficient (knockout) and aged wild-type mice; two situations associated with modifications of transbilayer distribution of cholesterol in brain synaptic plasma membranes. These results indicate that caveolin over-expression is linked to alterations of cholesterol distribution in the plasma membrane of brain cells and are consistent with the notion of a deterioration of cholesterol homeostasis in AD.

  14. Binding of nuclear caveolin-1 to promoter elements of growth-associated genes in ovarian carcinoma cells

    SciTech Connect

    Sanna, Elena; Miotti, Silvia . E-mail: silvia.miotti@istitutotumori.mi.it; Mazzi, Mimma; De Santis, Giuseppina; Canevari, Silvana; Tomassetti, Antonella

    2007-04-15

    Caveolin-1 (cav-1), a member of a protein family associated mainly with cell membrane microdomains in many cell types, acts as a tumor suppressor in ovarian carcinoma cells. Biochemical analyses demonstrated that cav-1 was also localized in the nuclei of ovarian carcinoma cells, endogenously (SKOV3) or ectopically (IGtC3) expressing cav-1. By confocal analyses, the same cell lines as well as IGROV1 and SKOV3 cells transiently transfected with green fluorescent protein-cav-1 fusion protein showed nuclear punctate speckled pattern. Subnuclear distribution analysis revealed cav-1 mainly associated with the nuclear matrix, but also slightly with chromatin. Cav-1 was found in nuclear high-molecular weight complexes and by confocal analysis was found to co-localized with the inner nuclear membrane protein emerin. Cyclin D1 and folate receptor promoters were modulated by cav-1 in SKOV3 cells as demonstrated by transient transfection with or silencing of cav-1. Chromatin immunoprecipitation and supershift assays indicated that nuclear cav-1 can bind in vitro and in vivo to promoter sequences of both cyclin D1 and folate receptor genes. These data suggest that in ovarian carcinoma cells cav-1, localized in transcriptionally inactive chromatin, exerts a functional activity mediated, at least in part, by directly binding to sequences of genes involved in proliferation.

  15. Expression of Stromal Caveolin- 1 May Be a Predictor for Aggressive Behaviour of Breast Cancer.

    PubMed

    Eliyatkin, Nuket; Aktas, Safiye; Diniz, Gulden; Ozgur, Halil Hakan; Ekin, Zubeyde Yildirim; Kupelioglu, Ali

    2017-02-24

    Caveolin-1 (Cav-1) is well known as a principal scaffolding protein of caveolae which are specialized plasma membrane structures. The role of Cav-1 in tumorigenesis of breast cancers is relatively less studied. The aim of the present study is to describe the biological roles of Cav-1 in breast cancers considering its contrasting dual functions as an oncogene and as a tumor suppressor. This study included 71 females with breast cancer who had been histopathologically diagnosed in Private Gunes Pathology Laboratory between the years 2007, and 2012. The mean age is 52.48 ± 12.8 years. Patients were followed up for a mean period of 47.97 ± 20.48 months. We didn't determine Cav-1 positive tumor cells. In 36 cases (50.7%), there were stromal expressions of Cav-1. In the statistical analysis, there was a statistically significant correlation between Cav-1 expression and ER (p = 0.033), metastasis (p = 0.005), lymphatic invasion (p = 0.000), nodal metastasis (p = 0,003), perinodal invasion (p = 0.003), metastasis (p = 0.005) and survival (p = 0.009). We found that Cav-1 expression is associated with tumor size, histological grade, lymph node involvement. Accordingly, we have suggested that Cav-1 may be a predictive biomarker for breast cancer.

  16. Extracellular matrix-specific Caveolin-1 phosphorylation on tyrosine 14 is linked to augmented melanoma metastasis but not tumorigenesis.

    PubMed

    Ortiz, Rina; Díaz, Jorge; Díaz, Natalia; Lobos-Gonzalez, Lorena; Cárdenas, Areli; Contreras, Pamela; Díaz, María Inés; Otte, Ellen; Cooper-White, Justin; Torres, Vicente; Leyton, Lisette; Quest, Andrew F G

    2016-06-28

    Caveolin-1 (CAV1) is a scaffolding protein that plays a dual role in cancer. In advanced stages of this disease, CAV1 expression in tumor cells is associated with enhanced metastatic potential, while, at earlier stages, CAV1 functions as a tumor suppressor. We recently implicated CAV1 phosphorylation on tyrosine 14 (Y14) in CAV1-enhanced cell migration. However, the contribution of this modification to the dual role of CAV1 in cancer remained unexplored. Here, we used in vitro [2D and transendothelial cell migration (TEM), invasion] and in vivo (metastasis) assays, as well as genetic and biochemical approaches to address this question in B16F10 murine melanoma cells. CAV1 promoted directional migration on fibronectin or laminin, two abundant lung extracellular matrix (ECM) components, which correlated with enhanced Y14 phosphorylation during spreading. Moreover, CAV1-driven migration, invasion, TEM and metastasis were ablated by expression of the phosphorylation null CAV1(Y14F), but not the phosphorylation mimicking CAV1(Y14E) mutation. Finally, CAV1-enhanced focal adhesion dynamics and surface expression of beta1 integrin were required for CAV1-driven TEM. Importantly, CAV1 function as a tumor suppressor in tumor formation assays was not altered by the Y14F mutation. In conclusion, our results provide critical insight to the mechanisms of CAV1 action during cancer development. Specific ECM-integrin interactions and Y14 phosphorylation are required for CAV1-enhanced melanoma cell migration, invasion and metastasis to the lung. Because Y14F mutation diminishes metastasis without inhibiting the tumor suppressor function of CAV1, Y14 phosphorylation emerges as an attractive therapeutic target to prevent metastasis without altering beneficial traits of CAV1.

  17. Extracellular matrix-specific Caveolin-1 phosphorylation on tyrosine 14 is linked to augmented melanoma metastasis but not tumorigenesis

    PubMed Central

    Ortiz, Rina; Díaz, Jorge; Díaz, Natalia; Lobos-Gonzalez, Lorena; Cárdenas, Areli; Contreras, Pamela; Díaz, María Inés; Otte, Ellen; Cooper-White, Justin; Torres, Vicente; Leyton, Lisette; Quest, Andrew F.G.

    2016-01-01

    Caveolin-1 (CAV1) is a scaffolding protein that plays a dual role in cancer. In advanced stages of this disease, CAV1 expression in tumor cells is associated with enhanced metastatic potential, while, at earlier stages, CAV1 functions as a tumor suppressor. We recently implicated CAV1 phosphorylation on tyrosine 14 (Y14) in CAV1-enhanced cell migration. However, the contribution of this modification to the dual role of CAV1 in cancer remained unexplored. Here, we used in vitro [2D and transendothelial cell migration (TEM), invasion] and in vivo (metastasis) assays, as well as genetic and biochemical approaches to address this question in B16F10 murine melanoma cells. CAV1 promoted directional migration on fibronectin or laminin, two abundant lung extracellular matrix (ECM) components, which correlated with enhanced Y14 phosphorylation during spreading. Moreover, CAV1-driven migration, invasion, TEM and metastasis were ablated by expression of the phosphorylation null CAV1(Y14F), but not the phosphorylation mimicking CAV1(Y14E) mutation. Finally, CAV1-enhanced focal adhesion dynamics and surface expression of beta1 integrin were required for CAV1-driven TEM. Importantly, CAV1 function as a tumor suppressor in tumor formation assays was not altered by the Y14F mutation. In conclusion, our results provide critical insight to the mechanisms of CAV1 action during cancer development. Specific ECM-integrin interactions and Y14 phosphorylation are required for CAV1-enhanced melanoma cell migration, invasion and metastasis to the lung. Because Y14F mutation diminishes metastasis without inhibiting the tumor suppressor function of CAV1, Y14 phosphorylation emerges as an attractive therapeutic target to prevent metastasis without altering beneficial traits of CAV1. PMID:27259249

  18. Caveolin-1: a critical regulator of lung injury

    PubMed Central

    Lee, Seon-Jin; Minshall, Richard D.; Choi, Augustine M. K.

    2011-01-01

    Caveolin-1 (cav-1), a 22-kDa transmembrane scaffolding protein, is the principal structural component of caveolae. Cav-1 regulates critical cell functions including proliferation, apoptosis, cell differentiation, and transcytosis via diverse signaling pathways. Abundant in almost every cell type in the lung, including type I epithelial cells, endothelial cells, smooth muscle cells, fibroblasts, macrophages, and neutrophils, cav-1 plays a crucial role in the pathogenesis of acute lung injury (ALI). ALI and its severe form, acute respiratory distress syndrome (ARDS), are responsible for significant morbidity and mortality in intensive care units, despite improvement in ventilation strategies. The pathogenesis of ARDS is still poorly understood, and therapeutic options remain limited. In this article, we summarize recent data regarding the regulation and function of cav-1 in lung biology and pathology, in particular as it relates to ALI. We further discuss the potential molecular and cellular mechanisms by which cav-1 expression contributes to ALI. Investigating the cellular functions of cav-1 may provide new insights for understanding the pathogenesis of ALI and provide novel targets for therapeutic interventions in the future. PMID:21097526

  19. Association of caveolin-1 genotypes with gastric cancer in Taiwan.

    PubMed

    Lin, Chih-Hsueh; Lin, Cheng-Chieh; Tsai, Chia-Wen; Chang, Wen-Shin; Yang, Chuan-Wei; Bau, Da-Tian

    2014-05-01

    Gastric cancer is one of the leading causes of tumor-related death worldwide, for which the prevalence and mortality rates are very high in developed countries. Caveolin-1 (Cav-1) is the main protein in the caveolin family and plays a role in tumorigenesis signaling. The contribution of CAV1 genetic variants to gastric cancer is still largely unknown. In the present study, we aimed to investigate the role of CAV1 genotypes in gastric cancer risk. We recruited 358 gastric patients and 358 cancer-free controls for CAV1 genotyping analysis. Six single-nucleotide polymorphisms (SNPs) of CAV1, C521A (rs1997623), G14713A (rs3807987), G21985A (12672038), T28608A (rs3757733), T29107A (rs7804372), and G32124A (rs3807992), were genotyped by the polymerase chain reaction-restriction fragment length polymorphism method. There was a significant difference between the gastric cancer and control groups in the genotypic frequency distribution of the CAV1 G14713A genotypes (p=1.24*10(-5)), with those carrying the A allele having a higher risk for gastric cancer compared to those with the GG genotype (p=0.0001). Our findings suggested that CAV1 genotype may determine the individual susceptibility to gastric cancer, and that the CAV1 G14713A genotype may serve as a novel biomarker for early detection and prediction of gastric cancer.

  20. Alterations of caveolin-1 expression in a mouse model of delayed cerebral vasospasm following subarachnoid hemorrhage

    PubMed Central

    Xiong, Ye; Wang, Xue-Min; Zhong, Ming; Li, Ze-Qun; Wang, Zhi; Tian, Zuo-Fu; Zheng, Kuang; Tan, Xian-Xi

    2016-01-01

    The aim of the present study was to evaluate the expression levels of caveolin-1 in the basilar artery following delayed cerebral vasospasm (DCVS) in a rat model of subarachnoid hemorrhage (SAH), in order to investigate the association between caveolin-1 and DCVS, and its potential as a treatment for DCVS of SAH. A total of 150 Sprague Dawley rats were randomly allocated into blank, saline and SAH groups. The SAH and saline groups were subdivided into days 3, 5, 7 and 14 following the establishment of the model. The murine model of SAH was established by double injection of autologous arterial blood into the cisterna magana and DCVS was detected using Bederson neurological severity scores. Hematoxylin and eosin (HE) staining was used to observe the inner perimeter of the basilar artery pipe and variations in the thickness of the basilar artery wall. Alterations in the levels of caveolin-1 protein in the basilar artery were measured using immunofluorescence and western blot analysis; whereas alterations in the mRNA expression levels of caveolin-1 were detected by reverse transcription-quantitative polymerase chain reaction. In the present study, 15 mice succumbed to SAH-induced DCVS in the day 3 (n=3), 5 (n=5) and 7 (n=2) groups. No mortality was observed in the blank control and saline groups during the process of observation in the SAH group, All mice in the SAH groups exhibited Bederson neurological severity scores ≥1; whereas no neurological impairment was detected in the blank and normal saline groups, demonstrating the success of the model. HE staining was used to assess vasospasm and the results demonstrated that the inner perimeter of the basal artery pipe decreased at day 3 in the SAH group; whereas values peaked in the day 7 group. The thickness of the basal artery wall significantly increased (P<0.05), as compared with the blank and saline groups, in which no significant alterations in the wall thickness and the inner perimeter of the basal artery pipe

  1. The role of caveolin-1 and syndecan-4 in the internalization of PEGylated PAMAM dendrimer polyplexes into myoblast and hepatic cells.

    PubMed

    Shen, Wenwen; van Dongen, Mallory A; Han, Yingchun; Yu, Maomao; Li, Yanzhi; Liu, George; Banaszak Holl, Mark M; Qi, Rong

    2014-11-01

    To improve gene delivery efficiency of PEGylated poly(amidoamine) dendrimers in livers and muscles, the roles of syndecan-4 receptor and caveolin-1 protein in the endocytosis of PEGylated generation 5 (G5-PEG) or 7 (G7-PEG) dendrimers and plasmid DNA polyplexes were explored in C2C12 and HepG2 cells. Expression levels of syndecan-4 for both cell lines were downregulated by transfection of the cells with syndecan-4 specific siRNA. Caveolin-1 was upregulated by infecting the cells with adenovirus vector expressed caveolin-1 (Ad-CAV-1). The impact of syndecan-4 and caveolin-1 on endocytosis of G5-PEG/DNA or G7-PEG/DNA polyplexes was then measured by flow cytometry. Our results demonstrate that downregulation of syndecan-4 and upregulation of caveolin-1 significantly improved internalization of PEG-PAMAM dendrimer polyplexes in HepG2 cells; however, in C2C12 cells, downregulation of syndecan-4 decreased the internalization of the polyplexes while upregulation of caveolin-1 had no effect on internalization. Gene expression results for G5-PEG/pGFP on the two cell lines exhibited the same trends for syndecan-4 and caveolin-1 as was observed for endocytosis of the polyplexes. This study gives a clue how to take strategies by up- or down-regulation of the expressions of syndecan-4 and caveolin-1 to improve in vivo gene delivery efficiency of the PEG-PAMAM dendrimers in clinical transgenic therapy.

  2. The Role of Caveolin-1 and Syndecan-4 in the Internalization of PEGylated PAMAM Dendrimer Polyplexes into Myoblast and Hepatic Cells

    PubMed Central

    Shen, Wenwen; van Dongen, Mallory A.; Han, Yingchun; Yu, Maomao; Li, Yanzhi; Liu, George; BanaszakHoll, Mark M.; Qi, Rong

    2014-01-01

    To improve gene delivery efficiency of PEGylated poly(amidoamine) dendrimers in livers and muscles, the roles of syndecan-4 receptor and caveolin-1 protein in the endocytosis of PEGylated generation 5 (G5-PEG) or 7 (G7-PEG) dendrimers and plasmid DNA polyplexes were explored in C2C12 and HepG2 cells. Expression levels of syndecan-4 for both cell lines were downregulated by transfection of the cells with syndecan-4 specific siRNA. Caveolin-1 was upregulated by infecting the cells with adenovirus vector expressed caveolin-1 (Ad-CAV-1). The impact of syndecan-4 and caveolin-1 on endocytosis of G5-PEG/DNA or G7-PEG/DNA polyplexes was then measured by flow cytometry. Our results demonstrate that downregulation of syndecan-4 and upregulation of caveolin-1 significantly improved internalization of PEG-PAMAM dendrimer polyplexes in HepG2 cells; however, in C2C12 cells, downregulation of syndecan-4 decreased the internalization of the polyplexes while upregulation of caveolin-1 had no effect on internalization. Gene expression results for G5-PEG/pGFP on the two cell lines exhibited the same trends for syndecan-4 and caveolin-1 as was observed for endocytosis of the polyplexes. This study gives a clue how to take strategies by up- or down-regulation of the expressions of Syndecan-4 and Caveolin-1 to improve in vivo gene delivery efficiency of the PEG-PAMAM dendrimers in clinical transgenic therapy. PMID:25083608

  3. Expression of caveolin-1 and podocalyxin in rat lungs challenged with 2-kDa macrophage-activating lipopeptide and Flt3L.

    PubMed

    Tschernig, T; Pabst, R; Kasper, M; El-Hadi, Mustafa; Singh, B

    2014-04-01

    Caveolin-1 is one of the important regulators of vascular permeability in inflamed lungs. Podocalyxin is a CD34 protein expressed on vascular endothelium and has a role in podocyte development in the kidney. Few data are available on the expression of caveolin-1 and podocalyxin in lungs challenged with Toll-like receptor 2 (TLR2) agonists such as mycoplasma-derived macrophage activating lipopeptide or with immune modulators such as Fms-like tyrosine kinase receptor-3 ligand (Flt3L), which expands dendritic cell populations in the lung. Because of the significance of pathogen-derived molecules that act through TLR2 and of the role of immune modulators in lung physiology, we examine the immunohistochemical expression of caveolin-1 and podocalyxin in lungs from rats challenged with a 2-kDa macrophage-activating lipopeptide (MALP-2) and Flt3L. Normal rat lungs expressed caveolin-1 in alveolar septa, vascular endothelium and airway epithelium, especially along the lateral borders of epithelial cells but not in alveolar macrophages. MALP-2 and Flt3L decreased and increased, respectively, the expression of caveolin-1. Caveolin-1 expression seemed to increase in microvessels in bronchiole-associated lymphoid tissue (BALT) in Flt3L-challenged lungs but not in normal or MALP-2-treated lungs. Podocalyxin was absent in the epithelium and alveolar macrophages but was present in the vasculature of control, Flt3L- and MALP-2-treated rats. Compared with control and MALP-2-treated rats, Flt3L-treated lungs showed greater expression of podocalyxin in BALT vasculature and at the interface of monocytes and the endothelium. These immunohistochemical data describing the altered expression of caveolin-1 and podocalyxin in lungs treated with MALP-2 or Flt3L encourage further mechanistic studies on the role of podocalyxin and caveolin-1 in lung inflammation.

  4. Potential Role of Caveolin-1 in Acetaminophen-Induced Hepatotoxicity

    PubMed Central

    Gardner, Carol R.; Gray, Joshua P.; Joseph, Laurie B.; Cervelli, Jessica; Bremer, Nicole; Kim, Yunjung; Mishin, Vladimir; Laskin, Jeffrey D.; Laskin, Debra L.

    2010-01-01

    Caveolin-1 (Cav-1) is a membrane scaffolding protein which functions to regulate intracellular compartmentalization of various signaling molecules. In the present studies, transgenic mice with a targeted disruption of the Cav-1 gene (Cav-1−/−) were used to assess the role of Cav-1 in acetaminophen-induced hepatotoxicity. Treatment of wild type mice with acetaminophen (300 mg/kg) resulted in centrilobular hepatic necrosis and increases in serum transaminases. This was correlated with decreased expression of Cav-1 in the liver. Acetaminophen-induced hepatotoxicity was significantly attenuated in Cav-1−/− mice, an effect that was independent of acetaminophen metabolism. Acetaminophen administration resulted in increased hepatic expression of the oxidative stress marker, lipocalin 24p3, as well as hemeoxygenase-1, but decreased glutathione and superoxide dismutase-1; no differences were noted between the genotypes suggesting that reduced toxicity in Cav-1−/− mice is not due to alterations in anti-oxidant defense. In wild type mice, acetaminophen increased mRNA expression of the pro-inflammatory cytokines, interleukin-1β and monocyte chemoattractant protein-1 (MCP-1), as well as cyclooxygenase-2, while 15-lipoxygenase (15-LOX), which generates anti-inflammatory lipoxins, decreased. Acetaminophen-induced changes in MCP-1 and 15-LOX expression were greater in Cav-1−/− mice. Although expression of tumor necrosis factor-α, a potent hepatocyte mitogen, was up-regulated in the liver of Cav-1−/− mice after acetaminophen, expression of proliferating cell nuclear antigen and survivin, markers of cellular proliferation, were delayed which may reflect the reduced need for tissue repair. Taken together, these data demonstrate that Cav-1 plays a role in promoting inflammation and toxicity during the pathogenesis of acetaminophen-induced injury. PMID:20100502

  5. Potential role of caveolin-1 in acetaminophen-induced hepatotoxicity

    SciTech Connect

    Gardner, Carol R.; Gray, Joshua P.; Joseph, Laurie B.; Cervelli, Jessica; Bremer, Nicole; Kim, Yunjung; Mishin, Vladimir; Laskin, Jeffrey D.; Laskin, Debra L.

    2010-05-15

    Caveolin-1 (Cav-1) is a membrane scaffolding protein, which functions to regulate intracellular compartmentalization of various signaling molecules. In the present studies, transgenic mice with a targeted disruption of the Cav-1 gene (Cav-1{sup -/-}) were used to assess the role of Cav-1 in acetaminophen-induced hepatotoxicity. Treatment of wild-type mice with acetaminophen (300 mg/kg) resulted in centrilobular hepatic necrosis and increases in serum transaminases. This was correlated with decreased expression of Cav-1 in the liver. Acetaminophen-induced hepatotoxicity was significantly attenuated in Cav-1{sup -/-} mice, an effect that was independent of acetaminophen metabolism. Acetaminophen administration resulted in increased hepatic expression of the oxidative stress marker, lipocalin 24p3, as well as hemeoxygenase-1, but decreased glutathione and superoxide dismutase-1; no differences were noted between the genotypes suggesting that reduced toxicity in Cav-1{sup -/-} mice is not due to alterations in antioxidant defense. In wild-type mice, acetaminophen increased mRNA expression of the pro-inflammatory cytokines, interleukin-1beta, and monocyte chemoattractant protein-1 (MCP-1), as well as cyclooxygenase-2, while 15-lipoxygenase (15-LOX), which generates anti-inflammatory lipoxins, decreased. Acetaminophen-induced changes in MCP-1 and 15-LOX expression were greater in Cav-1{sup -/-} mice. Although expression of tumor necrosis factor-alpha, a potent hepatocyte mitogen, was up-regulated in the liver of Cav-1{sup -/-} mice after acetaminophen, expression of proliferating cell nuclear antigen and survivin, markers of cellular proliferation, were delayed, which may reflect the reduced need for tissue repair. Taken together, these data demonstrate that Cav-1 plays a role in promoting inflammation and toxicity during the pathogenesis of acetaminophen-induced injury.

  6. Exercise type and muscle fiber specific induction of caveolin-1 expression for insulin sensitivity of skeletal muscle.

    PubMed

    Oh, Yoon Sin; Kim, Hyo Jeong; Ryu, Sung Jin; Cho, Kyung A; Park, Young Sik; Park, Hyon; Kim, MiJung; Kim, Chang Keun; Park, Sang Chul

    2007-06-30

    It is well known that exercise can have beneficial effects on insulin resistance by activation of glucose transporter. Following up our previous report that caveolin-1 plays an important role in glucose uptake in L6 skeletal muscle cells, we examined whether exercise alters the expression of caveolin-1, and whether exercise-caused changes are muscle fiber and exercise type specific. Fifty week-old Sprague Dawley (SD) rats were trained to climb a ladder and treadmill for 8 weeks and their soleus muscles (SOL) and extensor digitorum longus muscles (EDL) were removed after the last bout of exercise and compared with those from non-exercised animals. We found that the expression of insulin related proteins and caveolins did not change in SOL muscles after exercise. However, in EDL muscles, the expression of insulin receptor beta (IR beta) and glucose transporter-4 (GLUT-4) as well as phosphorylation of AKT and AMPK increased with resistance exercise but not with aerobic exercise. Also, caveolin-1 and caveolin-3 increased along with insulin related proteins only in EDL muscles by resistance exercise. These results suggest that upregulation of caveolin-1 in the skeletal muscle is fiber specific and exercise type specific, implicating the requirement of the specific mode of exercise to improve insulin sensitivity.

  7. Protein kinase C as a tumor suppressor.

    PubMed

    Newton, Alexandra C

    2017-05-02

    Protein kinase C (PKC) has historically been considered an oncoprotein. This stems in large part from the discovery in the early 1980s that PKC is directly activated by tumor-promoting phorbol esters. Yet three decades of clinical trials using PKC inhibitors in cancer therapies not only failed, but in some cases worsened patient outcome. Why has targeting PKC in cancer eluded successful therapies? Recent studies looking at the disease for insight provide an explanation: cancer-associated mutations in PKC are generally loss-of-function (LOF), supporting an unexpected function as tumor suppressors. And, contrasting with LOF mutations in cancer, germline mutations that enhance the activity of some PKC isozymes are associated with degenerative diseases such as Alzheimer's disease. This review provides a background on the diverse mechanisms that ensure PKC is only active when, where, and for the appropriate duration needed and summarizes recent findings converging on a paradigm reversal: PKC family members generally function by suppressing, rather than promoting, survival signaling. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. ACTH-induced caveolin-1 tyrosine phosphorylation is related to podosome assembly in Y1 adrenal cells

    SciTech Connect

    Colonna, Cecilia . E-mail: ccolonna@fmed.uba.ar; Podesta, Ernesto J.

    2005-04-01

    Y1 adrenocortical cells respond to ACTH with a characteristic rounding-up that facilitates cAMP signaling, critical for transport of cholesterol to the mitochondria and increase in steroid secretion. We here demonstrate that caveolin-1 participates in coupling activation of protein kinase A (PKA) to the control of cell shape. ACTH/8-Br-cAMP induced reorganization of caveolin-1-positive structures in correlation with the cellular rounding-up. Concomitant with this change, there was an increase in the phosphorylation of caveolin-1 (Tyr-14) localized at focal adhesions (FA) with reorganization of FA to rounded, ringlike structures. Colocalization with phalloidin showed that phosphocaveolin is present at the edge of actin filaments and that after ACTH stimulation F-actin dots at the cell periphery become surrounded by phosphocaveolin-1. These observations along with electron microscopy studies revealed these structures as podosomes. Podosome assembly was dependent on both PKA and tyrosine kinase activities because their formation was impaired after treatment with specific inhibitors [myristoylated PKI (mPKI) or PP2, respectively] previous to ACTH/8-Br-cAMP stimulation. These results show for the first time that ACTH induces caveolin-1 phosphorylation and podosome assembly in Y1 cells and support the view that the morphological and functional responses to PKA activation in steroidogenic cells are related to cytoskeleton dynamics.

  9. ACTH-induced caveolin-1 tyrosine phosphorylation is related to podosome assembly in Y1 adrenal cells.

    PubMed

    Colonna, Cecilia; Podestá, Ernesto J

    2005-04-01

    Y1 adrenocortical cells respond to ACTH with a characteristic rounding-up that facilitates cAMP signaling, critical for transport of cholesterol to the mitochondria and increase in steroid secretion. We here demonstrate that caveolin-1 participates in coupling activation of protein kinase A (PKA) to the control of cell shape. ACTH/8-Br-cAMP induced reorganization of caveolin-1-positive structures in correlation with the cellular rounding-up. Concomitant with this change, there was an increase in the phosphorylation of caveolin-1 (Tyr-14) localized at focal adhesions (FA) with reorganization of FA to rounded, ringlike structures. Colocalization with phalloidin showed that phosphocaveolin is present at the edge of actin filaments and that after ACTH stimulation F-actin dots at the cell periphery become surrounded by phosphocaveolin-1. These observations along with electron microscopy studies revealed these structures as podosomes. Podosome assembly was dependent on both PKA and tyrosine kinase activities because their formation was impaired after treatment with specific inhibitors [myristoylated PKI (mPKI) or PP2, respectively] previous to ACTH/8-Br-cAMP stimulation. These results show for the first time that ACTH induces caveolin-1 phosphorylation and podosome assembly in Y1 cells and support the view that the morphological and functional responses to PKA activation in steroidogenic cells are related to cytoskeleton dynamics.

  10. The role of beta(1)Pix/caveolin-1 interaction in endothelin signaling through Galpha subunits.

    PubMed

    Chahdi, Ahmed; Sorokin, Andrey

    2010-01-15

    Endothelin-1 (ET-1) is a potent mitogen that transmits signals through its cognate G protein-coupled receptors to stimulate extracellular signal-regulated kinase Erk1/2. Endothelin-1 receptors (ET-Rs) are known to interact with caveolin-1 and co-localize in caveolae which integrate different receptor and signaling proteins. We have recently shown that beta(1)Pix binds specifically to ET-Rs. Here, we show that beta(1)Pix binding to caveolin-1 is dependent on heterotrimeric G proteins activation state. beta(1)Pix interaction with different G proteins is increased in the presence of the G protein activator AMF. Moreover, extraction of cholesterol with methyl-beta-cyclodextrin disrupts the binding of beta(1)Pix to Galpha(q), Galpha(12) and phospho-Erk1/2 but not the binding of beta(1)Pix to G(beta1). The disruption of beta(1)Pix dimerization strongly reduced the binding of caveolin-1, Galpha(q) and Galpha(12). Constitutively active mutants of Galpha(q) and Galpha(12) increased Cdc42 activation when co-expressed with beta(1)Pix but not in the presence of beta(1)Pix dimerization deficient mutant beta(1)PixDelta (602-611). ET-1 stimulation increased the binding of phosphorylated Erk1/2 to beta(1)Pix but not to beta(1)PixDelta (602-611). RGS3 decreased ET-1-induced Cdc42 activation. These results strongly suggest that the activation of ET-Rs leads to the compartmentalization and the binding of Galpha(q) to beta(1)Pix in caveolae, where dimeric beta(1)Pix acts as platform to facilitate the binding and the activation of Erk1/2. Copyright 2009 Elsevier Inc. All rights reserved.

  11. Caveolin-1 influences human influenza A virus (H1N1) multiplication in cell culture

    PubMed Central

    2010-01-01

    Background The threat of recurring influenza pandemics caused by new viral strains and the occurrence of escape mutants necessitate the search for potent therapeutic targets. The dependence of viruses on cellular factors provides a weak-spot in the viral multiplication strategy and a means to interfere with viral multiplication. Results Using a motif-based search strategy for antiviral targets we identified caveolin-1 (Cav-1) as a putative cellular interaction partner of human influenza A viruses, including the pandemic influenza A virus (H1N1) strains of swine origin circulating from spring 2009 on. The influence of Cav-1 on human influenza A/PR/8/34 (H1N1) virus replication was determined in inhibition and competition experiments. RNAi-mediated Cav-1 knock-down as well as transfection of a dominant-negative Cav-1 mutant results in a decrease in virus titre in infected Madin-Darby canine kidney cells (MDCK), a cell line commonly used in basic influenza research as well as in virus vaccine production. To understand the molecular basis of the phenomenon we focussed on the putative caveolin-1 binding domain (CBD) located in the lumenal, juxtamembranal portion of the M2 matrix protein which has been identified in the motif-based search. Pull-down assays and co-immunoprecipitation experiments showed that caveolin-1 binds to M2. The data suggest, that Cav-1 modulates influenza virus A replication presumably based on M2/Cav-1 interaction. Conclusion As Cav-1 is involved in the human influenza A virus life cycle, the multifunctional protein and its interaction with M2 protein of human influenza A viruses represent a promising starting point for the search for antiviral agents. PMID:20504340

  12. Caveolin-1 Protects B6129 Mice against Helicobacter pylori Gastritis

    PubMed Central

    Hitkova, Ivana; Yuan, Gang; Anderl, Florian; Gerhard, Markus; Kirchner, Thomas; Reu, Simone; Röcken, Christoph; Schäfer, Claus; Schmid, Roland M.; Vogelmann, Roger; Ebert, Matthias P. A.; Burgermeister, Elke

    2013-01-01

    Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25+ regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies (“humming bird”) compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells. PMID:23592983

  13. The Ras-MAPK pathway downregulates Caveolin-1 in rodent fibroblast but not in human fibroblasts: implications in the resistance to oncogene-mediated transformation.

    PubMed

    Sasai, K; Kakumoto, K; Hanafusa, H; Akagi, T

    2007-01-18

    Normal human diploid fibroblasts (HDFs) are refractory to oncogene-mediated transformations in vitro, compared with rodent fibroblasts. As successful oncogene-mediated transformations of normal HDFs have been reported using the human telomerase catalytic subunit, it has been considered that telomerase activity contributes to the species-specific transformability. However, these transformed HDFs are much less malignant compared with those of rodent cells, suggesting the existence of undefined mechanisms that render HDFs resistant to malignant transformation. Here, cDNA microarray analysis identified caveolin-1 as one of the possible cellular factors involved in such mechanisms. The mitogen-activated protein kinases (MAPK) pathway downregulates Caveolin-1 in rodent fibroblasts, transformed by coexpression of the SV40 early region and activated H-Ras. In contrast, the coexpression of these two oncogenes in HDFs failed to reduce the expression level of Caveolin-1. These results strongly suggest the presence of critical differences in events following the phosphorylation of ERK during the activation process of the MAPK signaling pathway between human and rodent cells, as the ERK protein was similarly phosphorylated in both systems. Furthermore, the small interfering RNA-mediated suppression of Caveolin-1 facilitated the oncogene-mediated transformation of normal HDFs, clearly indicating that the differences in the transformability between human and rodent cells are due, at least in part, to the mechanism responsible for the resistance to Ras-induced Caveolin-1 downregulation in HDFs.

  14. [Interaction of two tumor suppressors: Phosphatase CTDSPL and Rb protein].

    PubMed

    Beniaminov, A D; Krasnov, G S; Dmitriev, A A; Puzanov, G A; Snopok, B A; Senchenko, V N; Kashuba, V I

    2016-01-01

    Earlier we established that CTDSPL gene encoding small carboxy-terminal domain serine phosphatase can be considered a classical tumor suppressor gene. Besides, transfection of tumor cell line MCF-7 with CTDSPL led to the content decrease of inactive phosphorylated form of another tumor suppressor, retinoblastoma protein (Rb), and subsequently to cell cycle arrest at the G1/S boundary. This result implied that small phosphatase CTDSPL is able to specifically dephosphorylate and activate Rb protein. In order to add some fuel to this hypothesis, in the present work we studied the interaction of two tumor suppressors CTDSPL and Rb in vitro. GST pool-down assay revealed that CTDSPL is able to precipitate Rb protein from MCF-7 cell extracts, while surface plasmon resonance technique showed that interaction of the two proteins is direct. Results of this study reassert that phosphatase CTDSPL and Rb could be involved in the common mechanism of cell cycle regulation.

  15. Caveolin-1, caveolin-3 and VEGF expression in the masticatory muscles of mdx mice.

    PubMed

    Kunert-Keil, Christiane; Gredes, Tomasz; Lucke, Silke; Morgenstern, Sven; Mielczarek, Agnieszka; Sporniak-Tutak, Katarzyna; Gedrange, Tomasz; Spassov, Alexander

    2011-01-01

    Duchenne muscular dystrophy (DMD) and murine X-linked muscular dystrophy (mdx), its murine model, are characterized by muscle damage and muscle weakness associated with inflammation and new vessel formation. Caveolins, dystrophin-associated proteins, are involved in the pathogenesis of DMD, because increased numbers of caveolae are found in DMD and mdx hindlimb muscles. Caveolae influence angiogenesis due to their content of vascular endothelial growth factor (VEGF) receptors. Orofacial muscles in mdx mice undergo muscle necrosis followed by muscle regeneration. To ascertain the role of caveolins and VEGF in the pathogenesis of dystrophic masticatory muscles, we examined the expression of caveolin-1 (cav-1), caveolin-3 (cav-3) and VEGF in control and mdx mice. In mdx masticatory muscles, no changes in transcript and protein levels of VEGF were found, whereas cav-1 and cav-3 expression was increased. Using immunohistochemistry, a strong sarcolemmal staining of caveolin-3 in regenerated muscle fibers was found. Furthermore, immunohistochemistry with the caveolin-1 antibody showed an increase in the amount of blood vessels in areas with regenerating muscle fibers. Dystrophic masticatory muscles showed changes comparable to those of hindlimb muscles in the expression of cav-1 and cav-3. The angiogenesis seems to be unaffected in the jaw muscles of mdx mice. We speculate that the increased caveolin expression could cause extensive and efficient muscle regeneration.

  16. Caveolin-1 mediates tissue plasminogen activator-induced MMP-9 up-regulation in cultured brain microvascular endothelial cells.

    PubMed

    Jin, Xinchun; Sun, Yanyun; Xu, Ji; Liu, Wenlan

    2015-03-01

    Thrombolysis with tissue plasminogen activator (tPA) increases matrix metalloproteinase-9 (MMP-9) activity in the ischemic brain, which exacerbates blood-brain barrier injury and increases the risk of symptomatic cerebral hemorrhage. The mechanism through which tPA enhances MMP-9 activity is not well understood. Here we report an important role of caveolin-1 in mediating tPA-induced MMP-9 synthesis. Brain microvascular endothelial cell line bEnd3 cells were incubated with 5 or 20 μg/ml tPA for 24 hrs before analyzing MMP-9 levels in the conditioned media and cellular extracts by gelatin zymography. tPA at a dose of 20 μg/mL tPA, but not 5 μg/mL, significantly increased MMP-9 level in cultured media while decreasing it in cellular extracts. Concurrently, tPA treatment induced a 2.3-fold increase of caveolin-1 protein levels in endothelial cells. Interestingly, knockdown of Cav-1 with siRNA inhibited tPA-induced MMP-9 mRNA up-regulation and MMP-9 increase in the conditioned media, but did not affect MMP-9 decrease in cellular extracts. These results suggest that caveolin-1 critically contributes to tPA-mediated MMP-9 up-regulation, but may not facilitate MMP-9 secretion in endothelial cells. Thrombolysis with tissue plasminogen activator (tPA) increases matrix metalloproteinase-9 (MMP-9) activity in the ischemic brain, which exacerbates ischemic blood brain barrier (BBB) injury and increases the risk of symptomatic cerebral hemorrhage. Our results suggest a novel mechanism underlying this tPA-MMP 9 axis. In response to tPA treatment, caveolin-1 protein levels increased in endothelial cells, which mediate MMP-9 mRNA up-regulation and its secretion into extracellular space. Caveolin-1 may, however, not facilitate MMP-9 secretion in endothelial cells. Our data suggest caveolin-1 as a novel therapeutic target for protecting the BBB against ischemic damage. The schematic outlines tPA-induced MMP-9 upreguation.

  17. Caveolin-1 expression in benign and malignant lesions of the breast

    PubMed Central

    Liedtke, Cornelia; Kersting, Christian; Bürger, Horst; Kiesel, Ludwig; Wülfing, Pia

    2007-01-01

    Background Caveolin-1 is thought to have an important impact on both signal transduction and mediation of intracellular processes. Furthermore, it has been suggested that Caveolin-1 may contribute to certain steps of carcinogenesis in various types of cancer. We examined the potential clinical relevance of Caveolin-1 in normal, benign and malignant breast tissue specimens. Methods Using tissue microarray (TMA) technology cases of invasive breast cancer, DCIS, benign breast disease (i.e. fibroadenoma, sclerosing adenosis, ductal hyperplasia and radial scar) and normal breast tissue were evaluated for Caveolin-1 expression. Immunohistochemical staining with an anti-Caveolin-1-antibody was performed. Staining intensity was quantified semiquantitatively. In invasive lesions staining results were correlated with clinical and pathological data. Results No Caveolin-1 expression was observed in epithelial cells of normal breast tissue (n = 5), benign breast disease (n = 295) and DCIS (n = 108). However, Caveolin-1 expression was found in 32 of 109 cases of invasive breast carcinomas (29.4%). Caveolin-1 expression in invasive breast cancer could neither be correlated with survival parameters such as overall or disease-free survival nor with established clinical and pathological markers. Conclusion In this study we demonstrated expression of Caveolin-1 in one third of invasive breast cancers. A significant increase in Caveolin-1 expression was observed comparing invasive breast cancer to both benign breast tissue and non-invasive breast cancer. Since inhibitors of Caveolin-1 signalling are available, targeting Caveolin-1 in breast cancer may represent a potential option for future breast cancer treatment. PMID:17915016

  18. Caveolin-1 is down-regulated in alveolar rhabdomyosarcomas and negatively regulates tumor growth

    PubMed Central

    Huertas-Martínez, Juan; Rello-Varona, Santiago; Herrero-Martín, David; Barrau, Ignasi; García-Monclús, Silvia; Sáinz-Jaspeado, Miguel; Lagares-Tena, Laura; Núñez-Álvarez, Yaiza; Mateo-Lozano, Silvia; Mora, Jaume; Roma, Josep; Toran, Nuria; Moran, Sebastian; López-Alemany, Roser; Gallego, Soledad; Esteller, Manel; Peinado, Miguel A.; Xavier García del, Muro; Tirado, Oscar M.

    2014-01-01

    Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence. Despite advances in therapy, patients with histological variant of rhabdomyosarcoma known as alveolar rhabdomyosarcoma (ARMS) have a 5-year survival of less than 30%. Caveolin-1 (CAV1), encoding the structural component of cellular caveolae, is a suggested tumor suppressor gene involved in cell signaling. In the present study we report that compared to other forms of rhabdomyosarcoma (RMS) CAV1 expression is either undetectable or very low in ARMS cell lines and tumor samples. DNA methylation analysis of the promoter region and azacytidine-induced re-expression suggest the involvement of epigenetic mechanisms in the silencing of CAV1. Reintroduction of CAV1 in three of these cell lines impairs their clonogenic capacity and promotes features of muscular differentiation. In vitro, CAV1-expressing cells show high expression of Caveolin-3 (CAV3), a muscular differentiation marker. Blockade of MAPK signaling is also observed. In vivo, CAV1-expressing xenografts show growth delay, features of muscular differentiation and increased cell death. In summary, our results suggest that CAV1 could function as a potent tumor suppressor in ARMS tumors. Inhibition of CAV1 function therefore, could contribute to aberrant cell proliferation, leading to ARMS development. PMID:25313138

  19. Lipid rafts, caveolae, caveolin-1, and entry by Chlamydiae into host cells.

    PubMed

    Stuart, Elizabeth S; Webley, Wilmore C; Norkin, Leonard C

    2003-07-01

    Obligate intracellular bacterial pathogens of the genus Chlamydia are reported to enter host cells by both clathrin-dependent and clathrin-independent processes. C. trachomatis serovar K recently was shown to enter cells via caveolae-like lipid raft domains. We asked here how widespread raft-mediated entry might be among the Chlamydia. We show that C. pneumoniae, an important cause of respiratory infections in humans that additionally is associated with cardiovascular disease, and C. psittaci, an important pathogen in domestic mammals and birds that also infects humans, each enter host cells via cholesterol-rich lipid raft microdomains. Further, we show that C. trachomatis serovars E and F also use these domains to enter host cells. The involvement of these membrane domains in the entry of these organisms was indicated by the sensitivity of their entry to the raft-disrupting agents Nystatin and filipin, and by their intracellular association with caveolin-1, a 22-kDa protein associated with the formation of caveolae in rafts. In contrast, caveolin-marked lipid raft domains do not mediate entry of C. trachomatis serovars A, 36B, and C, nor of LGV serovar L2 and MoPn. Finally, we show that entry of each of these chlamydial strains is independent of cellular expression of caveolin-1. Thus, entry via the Nystatin and filipin-sensitive pathway is dependent on lipid rafts containing cholesterol, rather than invaginated caveolae per se.

  20. Caveolin-1 expression and cavin stability regulate caveolae dynamics in adipocyte lipid store fluctuation.

    PubMed

    Briand, Nolwenn; Prado, Cécilia; Mabilleau, Guillaume; Lasnier, Françoise; Le Lièpvre, Xavier; Covington, Jeffrey D; Ravussin, Eric; Le Lay, Soazig; Dugail, Isabelle

    2014-12-01

    Adipocytes specialized in the storage of energy as fat are among the most caveolae-enriched cell types. Loss of caveolae produces lipodystrophic diabetes in humans, which cannot be reversed by endothelial rescue of caveolin expression in mice, indicating major importance of adipocyte caveolae. However, how caveolae participate in fat cell functions is poorly understood. We investigated dynamic conditions of lipid store fluctuations and demonstrate reciprocal regulation of caveolae density and fat cell lipid droplet storage. We identified caveolin-1 expression as a crucial step in adipose cell lines and in mice to raise the density of caveolae, to increase adipocyte ability to accommodate larger lipid droplets, and to promote cell expansion by increased glucose utilization. In human subjects enrolled in a trial of 8 weeks of overfeeding to promote fattening, adipocyte expansion response correlated with initial caveolin-1 expression. Conversely, lipid mobilization in cultured adipocytes to induce lipid droplet shrinkage led to biphasic response of cavin-1 with ultimate loss of expression of cavin-1 and -3 and EHD2 by protein degradation, coincident with caveolae disassembly. We have identified the key steps in cavin/caveolin interplay regulating adipocyte caveolae dynamics. Our data establish that caveolae participate in a unique cell response connected to lipid store fluctuation, suggesting lipid-induced mechanotension in adipocytes. © 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  1. Regulation of caveolin-1 expression, nitric oxide production and tissue injury by tumor necrosis factor-alpha following ozone inhalation.

    PubMed

    Fakhrzadeh, Ladan; Laskin, Jeffrey D; Laskin, Debra L

    2008-03-15

    Alveolar macrophages (AM) and inflammatory mediators including nitric oxide and peroxynitrite contribute to ozone-induced lung injury. The generation of these mediators is regulated, in part, by the transcription factor NF-kappaB. We previously demonstrated a critical role for NF-kappaB p50 in ozone-induced injury. In the present studies mechanisms regulating NF-kappaB activation in the lung after ozone inhalation were analyzed. Treatment of wild type (WT) mice with ozone (0.8 ppm, 3 h) resulted in a rapid increase in NF-kappaB binding activity in AM, which persisted for at least 12 h. This was not evident in mice lacking TNFalpha which are protected from ozone-induced injury; there was also no evidence of nitric oxide or peroxynitrite production in lungs from these animals. These data demonstrate that TNFalpha plays a role in NF-kappaB activation and toxicity. TNFalpha signaling involves PI-3-kinase (PI3K)/protein kinase B (PKB), and p44/42 MAP kinase (MAPK) which are important in NF-kappaB activation. Ozone Inhalation resulted in rapid and transient increases in p44/42 MAPK and PI3K/PKB in AM from WT mice, which was evident immediately after exposure. Caveolin-1, a transmembrane protein that negatively regulates PI3K/PKB and p44/42 MAPK signaling, was downregulated in AM from WT mice after ozone exposure. In contrast, ozone had no effect on caveolin-1, PI3K/PKB or p44/42 MAPK expression in AM from TNFalpha knockout mice. These data, together with our findings that TNFalpha suppressed caveolin-1 expression in cultured AM, suggest that TNFalpha and downstream signaling mediate activation of NF-kappaB and the regulation of inflammatory genes important in ozone toxicity, and that this process is linked to caveolin-1.

  2. Clinicopathological significance of caveolin-1 expression by cancer-associated fibroblasts in lung adenocarcinoma.

    PubMed

    Shimizu, Kei; Kirita, Keisuke; Aokage, Keiju; Kojima, Motohiro; Hishida, Tomoyuki; Kuwata, Takeshi; Fujii, Satoshi; Ochiai, Atsushi; Funai, Kazuhito; Yoshida, Junji; Tsuboi, Masahiro; Ishii, Genichiro

    2017-02-01

    Caveolin is an essential constituent of caveolae and has many biological functions. Expression of caveolin-1 in cancer cells was reported to be a prognostic marker in several types of cancers, the prognostic significance of its expression in cancer-associated fibroblasts (CAFs) has not been investigated. This study aimed to evaluate the clinicopathological significance of expression by CAFs in lung adenocarcinoma. We examined caveolin-1 expression in both CAFs and cancer cells in stage I invasive lung adenocarcinoma (n = 412) and analyzed the relationship between the expression and clinicopathological factors. Caveolin-1 expression by CAFs and cancer cells was observed in 12.1% and 7.8% of adenocarcinomas, respectively. Tumors with caveolin-1-positive CAFs had vascular and pleural invasion significantly more frequently than those with caveolin-1-negative CAF (p < 0.05). This was also the cases with tumors with caveolin-1-positive cancer cells (p < 0.01). Caveolin-1 expression by CAFs and that by cancer cells were significant predictors of shorter recurrence-free survival (p < 0.001). Caveolin-1 expression by CAFs and cancer cells was found in 25% and 30% of solid predominant subtype, respectively, but only 9.2% and 2.7% of non-solid predominant subtype, respectively. The frequency of cases with caveolin-1-positive CAFs or cancer cells was significantly higher in the solid predominant subtype than in non-solid predominant subtype (p < 0.001). Our current results highlight the prognostic importance of caveolin-1 expression by CAFs in stage I lung adenocarcinoma and provide new insights into the biological significance of caveolin-1 in the tumor microenvironment, especially in microenvironment of solid predominant adenocarcinoma.

  3. Down-regulation of caveolin-1 in glioma vasculature: modulation by radiotherapy.

    PubMed

    Régina, Anthony; Jodoin, Julie; Khoueir, Paul; Rolland, Yannève; Berthelet, France; Moumdjian, Robert; Fenart, Laurence; Cecchelli, Romeo; Demeule, Michel; Béliveau, Richard

    2004-01-15

    Primary brain tumors, particularly glioblastomas (GB), remain a challenge for oncology. An element of the malignant brain tumors' aggressive behavior is the fact that GB are among the most densely vascularized tumors. To determine some of the molecular regulations occuring at the brain tumor endothelium level during tumoral progression would be an asset in understanding brain tumor biology. Caveolin-1 is an essential structural constituent of caveolae that has been implicated in mitogenic signaling, oncogenesis, and angiogenesis. In this work we investigated regulation of caveolin-1 expression in brain endothelial cells (ECs) under angiogenic conditions. In vitro, brain EC caveolin-1 is down-regulated by angiogenic factors treament and by hypoxia. Coculture of brain ECs with tumoral cells induced a similar down-regulation. In addition, activation of the p42/44 MAP kinase is demonstrated. By using an in vivo brain tumor model, we purified ECs from gliomas as well as from normal brain to investigate possible regulation of caveolin-1 expression in tumoral brain vasculature. We show that caveolin-1 expression is strikingly down-regulated in glioma ECs, whereas an increase of phosphorylated caveolin-1 is observed. Whole-brain radiation treatment, a classical way in which GB is currently being treated, resulted in increased caveolin-1 expression in tumor isolated ECs. The level of tumor cells spreading around newly formed blood vessels was also elevated. The regulation of caveolin-1 expression in tumoral ECs may reflect the tumoral vasculature state and correlates with angiogenesis kinetics.

  4. Caveolae and Caveolin-1 Integrate Reverse Cholesterol Transport and Inflammation in Atherosclerosis

    PubMed Central

    Qin, Li; Zhu, Neng; Ao, Bao-Xue; Liu, Chan; Shi, Ya-Ning; Du, Ke; Chen, Jian-Xiong; Zheng, Xi-Long; Liao, Duan-Fang

    2016-01-01

    Lipid disorder and inflammation play critical roles in the development of atherosclerosis. Reverse cholesterol transport is a key event in lipid metabolism. Caveolae and caveolin-1 are in the center stage of cholesterol transportation and inflammation in macrophages. Here, we propose that reverse cholesterol transport and inflammation in atherosclerosis can be integrated by caveolae and caveolin-1. PMID:27011179

  5. Caveolae and Caveolin-1 Integrate Reverse Cholesterol Transport and Inflammation in Atherosclerosis.

    PubMed

    Qin, Li; Zhu, Neng; Ao, Bao-Xue; Liu, Chan; Shi, Ya-Ning; Du, Ke; Chen, Jian-Xiong; Zheng, Xi-Long; Liao, Duan-Fang

    2016-03-22

    Lipid disorder and inflammation play critical roles in the development of atherosclerosis. Reverse cholesterol transport is a key event in lipid metabolism. Caveolae and caveolin-1 are in the center stage of cholesterol transportation and inflammation in macrophages. Here, we propose that reverse cholesterol transport and inflammation in atherosclerosis can be integrated by caveolae and caveolin-1.

  6. Stromal Cell Expression of Caveolin-1 Predicts Outcome in Breast Cancer

    PubMed Central

    Sloan, Erica K.; Ciocca, Daniel R.; Pouliot, Normand; Natoli, Anthony; Restall, Christina; Henderson, Michael A.; Fanelli, Mariel A.; Cuello-Carrión, Fernando D.; Gago, Francisco E.; Anderson, Robin L.

    2009-01-01

    Caveolin-1 has been linked to tumor progression and clinical outcome in breast cancer, but a clear resolution of its role as a prognostic marker is lacking. We assessed caveolin-1 levels in normal breast tissue and two breast cancer cohorts for which outcome data were available. We found that caveolin-1 was not expressed in normal breast luminal epithelium but was present in the epithelial compartment of some tumors. We found no association between caveolin-1 expression in the epithelial compartment and clinical outcome. However, high levels of caveolin-1 in the stromal tissue surrounding the tumor, rather than within tumor cells, associated strongly with reduced metastasis and improved survival (P < 0.0001). The onset of mammary tumors driven by Her2/neu overexpression was accelerated in mice lacking caveolin-1, thereby supporting the observation that the presence of caveolin-1 in the tumor microenvironment modulates tumor development. These studies suggest that stromal caveolin-1 expression may be a potential therapeutic target and a valuable prognostic indicator of breast cancer progression. PMID:19411449

  7. Stromal cell expression of caveolin-1 predicts outcome in breast cancer.

    PubMed

    Sloan, Erica K; Ciocca, Daniel R; Pouliot, Normand; Natoli, Anthony; Restall, Christina; Henderson, Michael A; Fanelli, Mariel A; Cuello-Carrión, Fernando D; Gago, Francisco E; Anderson, Robin L

    2009-06-01

    Caveolin-1 has been linked to tumor progression and clinical outcome in breast cancer, but a clear resolution of its role as a prognostic marker is lacking. We assessed caveolin-1 levels in normal breast tissue and two breast cancer cohorts for which outcome data were available. We found that caveolin-1 was not expressed in normal breast luminal epithelium but was present in the epithelial compartment of some tumors. We found no association between caveolin-1 expression in the epithelial compartment and clinical outcome. However, high levels of caveolin-1 in the stromal tissue surrounding the tumor, rather than within tumor cells, associated strongly with reduced metastasis and improved survival (P < 0.0001). The onset of mammary tumors driven by Her2/neu overexpression was accelerated in mice lacking caveolin-1, thereby supporting the observation that the presence of caveolin-1 in the tumor microenvironment modulates tumor development. These studies suggest that stromal caveolin-1 expression may be a potential therapeutic target and a valuable prognostic indicator of breast cancer progression.

  8. Nanoscale imaging of caveolin-1 membrane domains in vivo.

    PubMed

    Gabor, Kristin A; Kim, Dahan; Kim, Carol H; Hess, Samuel T

    2015-01-01

    Light microscopy enables noninvasive imaging of fluorescent species in biological specimens, but resolution is generally limited by diffraction to ~200-250 nm. Many biological processes occur on smaller length scales, highlighting the importance of techniques that can image below the diffraction limit and provide valuable single-molecule information. In recent years, imaging techniques have been developed which can achieve resolution below the diffraction limit. Utilizing one such technique, fluorescence photoactivation localization microscopy (FPALM), we demonstrated its ability to construct super-resolution images from single molecules in a living zebrafish embryo, expanding the realm of previous super-resolution imaging to a living vertebrate organism. We imaged caveolin-1 in vivo, in living zebrafish embryos. Our results demonstrate the successful image acquisition of super-resolution images in a living vertebrate organism, opening several opportunities to answer more dynamic biological questions in vivo at the previously inaccessible nanoscale.

  9. Nanoscale Imaging of Caveolin-1 Membrane Domains In Vivo

    PubMed Central

    Gabor, Kristin A.; Kim, Dahan; Kim, Carol H.; Hess, Samuel T.

    2015-01-01

    Light microscopy enables noninvasive imaging of fluorescent species in biological specimens, but resolution is generally limited by diffraction to ~200–250 nm. Many biological processes occur on smaller length scales, highlighting the importance of techniques that can image below the diffraction limit and provide valuable single-molecule information. In recent years, imaging techniques have been developed which can achieve resolution below the diffraction limit. Utilizing one such technique, fluorescence photoactivation localization microscopy (FPALM), we demonstrated its ability to construct super-resolution images from single molecules in a living zebrafish embryo, expanding the realm of previous super-resolution imaging to a living vertebrate organism. We imaged caveolin-1 in vivo, in living zebrafish embryos. Our results demonstrate the successful image acquisition of super-resolution images in a living vertebrate organism, opening several opportunities to answer more dynamic biological questions in vivo at the previously inaccessible nanoscale. PMID:25646724

  10. Caveolin-1 and cancer metabolism in the tumor microenvironment: markers, models, and mechanisms.

    PubMed

    Sotgia, Federica; Martinez-Outschoorn, Ubaldo E; Howell, Anthony; Pestell, Richard G; Pavlides, Stephanos; Lisanti, Michael P

    2012-01-01

    Caveolins are a family of membrane-bound scaffolding proteins that compartmentalize and negatively regulate signal transduction. Recent studies have implicated a loss of caveolin-1 (Cav-1) expression in the pathogenesis of human cancers. Loss of Cav-1 expression in cancer-associated fibroblasts results in an activated tumor microenvironment, thereby driving early tumor recurrence, metastasis, and poor clinical outcome in breast and prostate cancers. We describe various paracrine signaling mechanism(s) by which the loss of stromal Cav-1 promotes tumor progression, including fibrosis, extracellular matrix remodeling, and the metabolic/catabolic reprogramming of cancer-associated fibroblast, to fuel the growth of adjacent tumor cells. It appears that oxidative stress is the root cause of initiation of the loss of stromal Cav-1 via autophagy, which provides further impetus for the use of antioxidants in anticancer therapy. Finally, we discuss the functional role of Cav-1 in epithelial cancer cells.

  11. Caveolin-1 in the regulation of cell metabolism: a cancer perspective.

    PubMed

    Nwosu, Zeribe Chike; Ebert, Matthias Philip; Dooley, Steven; Meyer, Christoph

    2016-11-16

    Caveolin-1 (CAV1) is an oncogenic membrane protein associated with endocytosis, extracellular matrix organisation, cholesterol distribution, cell migration and signaling. Recent studies reveal that CAV1 is involved in metabolic alterations - a critical strategy adopted by cancer cells to their survival advantage. Consequently, research findings suggest that CAV1, which is altered in several cancer types, influences tumour development or progression by controlling metabolism. Understanding the molecular interplay between CAV1 and metabolism could help uncover druggable metabolic targets or pathways of clinical relevance in cancer therapy. Here we review from a cancer perspective, the findings that CAV1 modulates cell metabolism with a focus on glycolysis, mitochondrial bioenergetics, glutaminolysis, fatty acid metabolism, and autophagy.

  12. Lysine methylation regulates the pRb tumour suppressor protein.

    PubMed

    Munro, S; Khaire, N; Inche, A; Carr, S; La Thangue, N B

    2010-04-22

    The pRb tumour suppressor protein has a central role in coordinating early cell cycle progression. An important level of control imposed on pRb occurs through post-translational modification, for example, phosphorylation. We describe here a new level of regulation on pRb, mediated through the targeted methylation of lysine residues, by the methyltransferase Set7/9. Set7/9 methylates the C-terminal region of pRb, both in vitro and in cells, and methylated pRb interacts with heterochromatin protein HP1. pRb methylation is required for pRb-dependent cell cycle arrest and transcriptional repression, as well as pRb-dependent differentiation. Our results indicate that methylation can influence the properties of pRb, and raise the interesting possibility that methylation modulates pRb tumour suppressor activity.

  13. Genes encoding human caveolin-1 and -2 are co-localized to the D7S522 locus (7q31.1), a known fragile site (FRA7G) that is frequently deleted in human cancers.

    PubMed

    Engelman, J A; Zhang, X L; Lisanti, M P

    1998-10-09

    The (CA)n microsatellite repeat marker D7S522 is located on human chromosome 7q31.1 and is frequently deleted in a variety of human cancers, including squamous cell carcinomas of the head and neck, prostate cancers, renal cell carcinomas, ovarian adenocarcinomas, colon carcinomas, and breast cancers. In addition, D7S522 spans FRA7G, a known common fragile site on human chromosome 7. Based on these studies, it has been proposed that an as yet unidentified tumor suppressor gene (or genes) is contained within or located in close proximity to this locus. However, the identity of the candidate tumor suppressor gene at the D7S522 locus remains unknown. Here, we show that the human genes encoding caveolins 1 and 2 are contained within the same human genomic BAC clones and co-localize to the q31.1-q31.2 region of human chromosome 7, as seen by FISH analysis. In addition, we determined the intron-exon boundaries of the human caveolin-1 and -2 genes. The human caveolin-1 gene contains three exons, while the human caveolin-2 gene contains two exons. Interestingly, the boundary of the last exon of the human caveolin-1 and caveolin-2 genes are analogous, suggesting that they arose through gene duplication at this locus. (CA)n microsatellite repeat marker analysis of these caveolin genomic clones indicates they contain the marker D7S522 (located at 7q31.1), but not other microsatellite repeat markers tested. The close proximity of caveolins 1 and 2 to the D7S522 locus was independently confirmed by using a panel of MIT/Whitehead human STS markers that are known to map in the neighborhood of the D7S522 locus. As it has been previously shown that caveolin 1 possesses transformation suppressor activity (Koleske, A.J., Baltimore, D. and M.P. Lisanti (1995) Proc. Natl. Acad. Sci. USA 92, 1381-1385; Engelman, J.A. et al. (1997) J. Biol. Chem. 272, 16374-16381), we propose that the caveolin-1 gene may represent the candidate tumor suppressor gene at the D7S522 locus on human chromosome

  14. Differential proteomic analysis of caveolin-1 KO cells reveals Sh2b3 and Clec12b as novel interaction partners of caveolin-1 and capns1 as potential mediator of caveolin-1-induced apoptosis

    PubMed Central

    Kulkarni, Yogesh M; Liu, Changxing; Qi, Qi; Zhu, Yanmei; Klinke, David J; Liu, Jun

    2014-01-01

    Caveolin-1 (Cav1) is a small scaffolding protein implicated in a variety of cellular functions, including cell signaling, lipid transport and membrane traffic. The objective of this study was to use comparative proteomics to identify differentially expressed proteins in Cav1 knockout (KO) mouse embryonic fibroblasts. These deregulated proteins were then analyzed using systems biology tools to gain insight into the local network properties and to identify the interaction partners of Cav1. We identified five proteins that were up-regulated and ten proteins that were down-regulated in Cav1 KO cells, suggesting that the local network behaves as a complex system. Protein interaction network analysis revealed two proteins, Sh2b3 and Clec12b, as novel interaction partners of Cav1. Functional annotation showed apoptosis signaling as the most significant pathway. To validate this functional annotation, Cav1 KO cells showed more than 1.5-fold increase in caspase-3 activity over wild type cells upon apoptotic stimulation. We also found that calpain small subunit 1 is up-regulated in Cav1 KO cells and directly influences cell response to apoptotic stimuli. Moreover, Capns1 was reduced in Cav1 KO cells following re-expression of Cav1 and suppression of Capns1 activity in Cav1 KO cells significantly inhibited the sensitivity to apoptotic stimuli, as measured by caspase 3 activity. In conclusion, our results suggest that Sh2b3 and Clec12b functionally interact with Cav1 and that calpain small subunit 1 may mediate Cav1-induced apoptosis. PMID:24091439

  15. Caveolin-1 is necessary for hepatic oxidative lipid metabolism: evidence for crosstalk between caveolin-1 and bile acid signaling.

    PubMed

    Fernández-Rojo, Manuel A; Gongora, Milena; Fitzsimmons, Rebecca L; Martel, Nick; Martin, Sheree D; Nixon, Susan J; Brooks, Andrew J; Ikonomopoulou, Maria P; Martin, Sally; Lo, Harriet P; Myers, Stephen A; Restall, Christina; Ferguson, Charles; Pilch, Paul F; McGee, Sean L; Anderson, Robin L; Waters, Michael J; Hancock, John F; Grimmond, Sean M; Muscat, George E O; Parton, Robert G

    2013-07-25

    Caveolae and caveolin-1 (CAV1) have been linked to several cellular functions. However, a model explaining their roles in mammalian tissues in vivo is lacking. Unbiased expression profiling in several tissues and cell types identified lipid metabolism as the main target affected by CAV1 deficiency. CAV1-/- mice exhibited impaired hepatic peroxisome proliferator-activated receptor α (PPARα)-dependent oxidative fatty acid metabolism and ketogenesis. Similar results were recapitulated in CAV1-deficient AML12 hepatocytes, suggesting at least a partial cell-autonomous role of hepatocyte CAV1 in metabolic adaptation to fasting. Finally, our experiments suggest that the hepatic phenotypes observed in CAV1-/- mice involve impaired PPARα ligand signaling and attenuated bile acid and FXRα signaling. These results demonstrate the significance of CAV1 in (1) hepatic lipid homeostasis and (2) nuclear hormone receptor (PPARα, FXRα, and SHP) and bile acid signaling.

  16. Static pressure accelerates ox-LDL-induced cholesterol accumulation via SREBP-1-mediated caveolin-1 downregulation in cultured vascular smooth muscle cells

    SciTech Connect

    Luo, Di-xian; Xia, Cheng-lai; Li, Jun-mu; Xiong, Yan; Yuan, Hao-yu; TANG, Zhen-Wang; Zeng, Yixin; Liao, Duan-fang

    2010-12-03

    Research highlights: {yields} Vertical static pressure accelerates ox-LDL-induced cholesterol accumulation in cultured vascular smooth muscle cells. {yields} Static pressure induces SREBP-1 activation. {yields} Static pressure downregulates the expressions of caveolin-1 by activating SREBP-1. {yields} Static pressure also downregulates the transcription of ABCA1 by activating SREBP-1. {yields} Static pressure increases ox-LDL-induced cholesterol accumulation by SREBP-1-mediated caveolin-1 downregulation in vascular smooth muscle cells cultured in vitro. -- Abstract: Objective: To investigate the effect of static pressure on cholesterol accumulation in vascular smooth muscle cells (VSMCs) and its mechanism. Methods: Rat-derived VSMC cell line A10 treated with 50 mg/L ox-LDL and different static pressures (0, 60, 90, 120, 150, 180 mm Hg) in a custom-made pressure incubator for 48 h. Intracellular lipid droplets and lipid levels were assayed by oil red O staining and HPLC; The mRNA levels of caveolin-1 and ABCA1, the protein levels of caveolin-1 SREBP-1 and mature SREBP-1 were respectively detected by RT-PCR or western blot. ALLN, an inhibitor of SREBP metabolism, was used to elevate SREBP-1 protein level in VSMCs treated with static pressure. Results: Static pressures significantly not only increase intracellular lipid droplets in VSMCs, but also elevate cellular lipid content in a pressure-dependent manner. Intracellular free cholesterol (FC), cholesterol ester (CE), total cholesterol (TC) were respectively increased from 60.5 {+-} 2.8 mg/g, 31.8 {+-} 0.7 mg/g, 92.3 {+-} 2.1 mg/g at atmosphere pressure (ATM, 0 mm Hg) to 150.8 {+-} 9.4 mg/g, 235.9 {+-} 3.0 mg/g, 386.7 {+-} 6.4 mg/g at 180 mm Hg. At the same time, static pressures decrease the mRNA and protein levels of caveolin-1, and induce the activation and nuclear translocation of SREBP-1. ALLN increases the protein level of mature SREBP-1 and decreases caveolin-1 expression, so that cellular lipid levels were

  17. Fyn is required for oxidative- and hyperosmotic-stress-induced tyrosine phosphorylation of caveolin-1.

    PubMed Central

    Sanguinetti, Amy R; Cao, Haiming; Corley Mastick, Cynthia

    2003-01-01

    Caveolin-1 is phosphorylated on Tyr(14) in response to both oxidative and hyperosmotic stress. In the present paper, we show that this phosphorylation requires activation of the Src family kinase Fyn. Stress-induced caveolin phosphorylation was abolished by three Src kinase inhibitors, SU6656, PP2 and PD180970, and was not observed in fibroblasts derived from a Src, Yes and Fyn triple-knockout mouse (SYF-/-). Using cell lines derived from single-kinase-knockout mice (Src-/-, Yes-/- and Fyn-/-), we show that expression of Fyn, but not Src or Yes, is required for stress-induced caveolin phosphorylation. Heterologous expression of Fyn in the SYF-/- and Fyn-/- cells was sufficient to reconstitute stress-induced caveolin phosphorylation, and overexpression of Fyn in wild-type cells induced hyperphosphorylation of caveolin. Fyn was autophosphorylated following oxidative stress, verifying activation of this kinase. Interestingly, there was a concomitant increase in the phosphorylation of Fyn on its Csk (C-terminal Src kinase) site, indicating feedback inhibition. Csk binds to phosphocaveolin [Cao, Courchesne and Mastick (2002) J. Biol. Chem. 277, 8771-8774] and should phosphorylate any co-localized Src-family kinases. Oxidative-stress-induced phosphorylation of caveolin-1 also requires expression of Abl [Sanguinetti and Mastick (2003) Cell Signal. 15, 289-298]. Using inhibitors and cells derived from knockout mice, we verified a requirement for both Abl and Fyn in stress-induced caveolin phosphorylation in a single cell type. Our data suggest a novel mechanism for attenuation of Src-kinase activity by Abl: stable tyrosine phosphorylation of a scaffolding protein, caveolin, and recruitment of Csk. Paxillin, a substrate of both Abl and Src, organizes a similar regulatory complex. PMID:12921535

  18. The tumor suppressor protein Fhit. A novel interaction with tubulin.

    PubMed

    Chaudhuri, A R; Khan, I A; Prasad, V; Robinson, A K; Ludueña, R F; Barnes, L D

    1999-08-20

    FHIT (fragile histidine triad) is a candidate human tumor suppressor gene located at chromosome 3p14.2, a location that encompasses the FRA3B chromosomal fragile site. Aberrant transcripts have been detected in a variety of primary tumors, and homozygous deletions in the FHIT locus have been detected in different tumor cell lines. The gene product Fhit in vitro possesses the ability to hydrolyze diadenosine 5',5"'-P(1),P(3)-triphosphate (Ap(3)A). The mechanism of action of Fhit as a tumor suppressor is unknown. Because the tubulin-microtubule system plays an important role in cell division and cell proliferation, we investigated the interaction between wild-type Fhit or mutant Fhit (H96N) and tubulin in vitro. The mutant form of Fhit (H96N) lacks Ap(3)A hydrolase activity but retains tumor suppressor activity. We found that both wild-type and mutated forms of Fhit bind to tubulin strongly and specifically with K(d) values of 1.4 and 2.1 microM, respectively. Neither wild-type nor mutant Fhit cause nucleation or formation of microtubules, but in the presence of microtubule-associated proteins, both wild-type and mutant Fhit promote assembly to a greater extent than do microtubule-associated proteins alone, and the microtubules formed appear normal by electron microscopy. Our results suggest the possibility that Fhit may exert its tumor suppressor activity by interacting with microtubules and also indicate that the interaction between Fhit and tubulin is not related to the Ap(3)A hydrolase activity of Fhit.

  19. Clathrin- and caveolin-1–independent endocytosis

    PubMed Central

    Damm, Eva-Maria; Pelkmans, Lucas; Kartenbeck, Jürgen; Mezzacasa, Anna; Kurzchalia, Teymuras; Helenius, Ari

    2005-01-01

    Simian Virus 40 (SV40) has been shown to enter host cells by caveolar endocytosis followed by transport via caveosomes to the endoplasmic reticulum (ER). Using a caveolin-1 (cav-1)–deficient cell line (human hepatoma 7) and embryonic fibroblasts from a cav-1 knockout mouse, we found that in the absence of caveolae, but also in wild-type embryonic fibroblasts, the virus exploits an alternative, cav-1–independent pathway. Internalization was rapid (t1/2 = 20 min) and cholesterol and tyrosine kinase dependent but independent of clathrin, dynamin II, and ARF6. The viruses were internalized in small, tight-fitting vesicles and transported to membrane-bounded, pH-neutral organelles similar to caveosomes but devoid of cav-1 and -2. The viruses were next transferred by microtubule-dependent vesicular transport to the ER, a step that was required for infectivity. Our results revealed the existence of a virus-activated endocytic pathway from the plasma membrane to the ER that involves neither clathrin nor caveolae and that can be activated also in the presence of cav-1. PMID:15668298

  20. Pigment epithelium-derived factor (PEDF) binds to caveolin-1 and inhibits the pro-inflammatory effects of caveolin-1 in endothelial cells.

    PubMed

    Matsui, Takanori; Higashimoto, Yuichiro; Taira, Junichi; Yamagishi, Sho-ichi

    2013-11-15

    Pigment epithelium-derived factor (PEDF) exerts atheroprotective effects both in cell culture and animal models through its anti-oxidative and anti-inflammatory properties. Caveolin-1 (Cav), a major protein component of caveolae in endothelial cells (ECs), plays a role in the progression of atherosclerosis. However, effects of PEDF on Cav-exposed ECs remain unknown. In this study, we examined whether and how PEDF could inhibit the Cav-induced inflammatory and thrombogenic reactions in human umbilical vein ECs (HUVECs). Surface plasmon resonance revealed that PEDF bound to Cav at the dissociation constant of 7.36×10(-7) M. Further, one of the major Cav-interacting proteins in human serum was identified as PEDF by peptide mass fingerprinting analysis using BIAcore 1000 combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Exogenously added Cav was taken up into the membrane fraction of HUVECs and dose-dependently increased monocyte chemoattractant protein-1 (MCP-1), vascular cell adhesion molecule-1 (VCAM-1) and plasminogen activator inhibitor-1 (PAI-1) mRNA levels, all of which were blocked by the simultaneous treatment with 10nM PEDF. Small interfering RNAs directed against Cav decreased endogenous Cav levels and suppressed gene expression of MCP-1, VCAM-1 and PAI-1 in HUVECs. This study indicates that PEDF binds to Cav and could block the inflammatory and thrombogenic reactions in Cav-exposed HUVECs. Our present study suggests that atheroprotective effects of PEDF might be partly ascribed to its Cav-interacting properties.

  1. Prognostic and predictive values of SPP1, PAI and caveolin-1 in patients with oral squamous cell carcinoma.

    PubMed

    Huang, Cong-Fa; Yu, Guang-Tao; Wang, Wei-Ming; Liu, Bing; Sun, Zhi-Jun

    2014-01-01

    SPP1, PAI and caveolin-1 are known to be closely associated with tumor progression in several kinds of human tumors. This study aimed to investigate the expression of SPP1, PAI and caveolin-1 in oral squamous cell carcinoma (OSCC), and to evaluate their association with the prognosis in oral carcinoma. Immunohistochemical staining was used to examine the expression of SPP1, PAI and caveolin-1 in 17 normal oral mucosa, 6 oral epithelial dysplasia and 43 OSCC specimens by tissue microarrays. High expression of SPP1, PAI and caveolin-1 was found in OSCC patients, and SPP1 and PAI expression were significantly higher in OSCC than in normal oral mucosa. No significant correlations were found between SPP1, PAI and caveolin-1 expression and clinicopathological factors. Expression of SPP1, PAI and caveolin-1 was also not associated with overall survival. Moreover, SPP1 was closely correlated with PAI, caveolin-1 and Keap1, and PAI had significant correlations with caveolin-1, Keap1 and Nrf2, and caveolin-1 was associated with Keap1 by using the Pearson correlation coefficient test. Our findings suggest that overexpressed SPP1, PAI and caveolin-1 were linked to carcinogenesis and progression, and thus they may serve as potential prognostic factors in OSCC.

  2. Activation and activities of the p53 tumour suppressor protein

    PubMed Central

    Bálint, É; Vousden, K H

    2001-01-01

    The p53 tumour suppressor protein inhibits malignant progression by mediating cell cycle arrest, apoptosis or repair following cellular stress. One of the major regulators of p53 function is the MDM2 protein, and multiple forms of cellular stress activate p53 by inhibiting the MDM2-mediated degradation of p53. Mutations in p53, or disruption of the pathways that allow activation of p53, seem to be a general feature of all cancers. Here we review recent advances in our understanding of the pathways that regulate p53 and the pathways that are induced by p53, as well as their implications for cancer therapy. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11747320

  3. Prognostic Value of Metastatic Tumoral Caveolin-1 Expression in Patients with Resected Gastric Cancer

    PubMed Central

    Sun, Der Sheng; Won, Hye Sung; Lee, Han Hong

    2017-01-01

    Objective Caveolin-1 (Cav-1), as the main component of caveolae, has complex roles in tumourigenesis in human malignancies. We investigated Cav-1 in primary and metastatic tumor cells of gastric cancer (GC) and its association with clinical outcomes. Methods We retrieved 145 cases of GC who had undergone curative gastrectomy. The expression levels of Cav-1 was evaluated by immunohistochemistry, and its association with clinicopathological parameters and patient survival was analyzed. Results High expression of Cav-1 protein of the GC in the stomach and metastatic lymph node was 12.4% (18/145) and 16.5% (15/91). In the multivariate analysis, tumoral Cav-1 protein in metastatic lymph node showed prognostic significance for relapse-free survival (RFS, HR, 3.934; 95% CI, 1.882–8.224; P = 0.001) and cancer-specific survival outcome (CSS, HR, 2.681; 95% CI, 1.613–8.623; P = 0.002). Among the GCs with metastatic lymph node, it remained as a strong indicator of poor prognosis for RFS (HR, 3.136; 95% CI, 1.444–6.810; P = 0.004) and CSS (HR, 2.509; 95% CI, 1.078–5.837; P = 0.032). Conclusion High expression of tumoral Cav-1 protein in metastatic lymph node is associated with unfavorable prognosis of curative resected GC, indicating the potential of novel prognostic markers. PMID:28828003

  4. Chloride channel ClC- 2 enhances intestinal epithelial tight junction barrier function via regulation of caveolin-1 and caveolar trafficking of occludin.

    PubMed

    Nighot, Prashant K; Leung, Lana; Ma, Thomas Y

    2017-03-01

    Previous studies have demonstrated that the chloride channel ClC-2 plays a critical role in intestinal epithelial tight junction (TJ) barrier function via intracellular trafficking of TJ protein occludin. To study the mechanism of ClC-2-mediated TJ barrier function and intracellular trafficking of occludin, we established ClC-2 over-expressing Caco-2 cell line (Caco-2(CLCN2)) by full length ClC-2 ORF transfection. ClC-2 over-expression (Caco-2(CLCN2)) significantly enhanced TJ barrier (increased TER by ≥2 times and reduced inulin flux by 50%) compared to control Caco-2(pEZ) cells. ClC-2 over-expression (Caco-2(CLCN2)) increased occludin protein level compared to control Caco-2(pEZ) cells. Surface biotinylation assay revealed reduced steady state endocytosis of occludin in Caco-2(CLCN2) cells. Furthermore, ClC-2 over-expression led to reduction in caveolin-1 protein level and diminishment of caveolae assembly. Caveolae disruption increased TJ permeability in control but not ClC-2 over-expressing Caco-2(CLCN2) cells. Selective ClC-2 channel blocker GaTx2 caused an increase in caveolin-1 protein level and reduced occludin level. Delivery of cell permeable caveolin-1 scaffolding domain reduced the occludin protein level. Over all, these results suggest that ClC- 2 enhances TJ barrier function in intestinal epithelial cells via regulation of caveolin-1 and caveolae-mediated trafficking of occludin.

  5. C-terminus of human BKca channel alpha subunit enhances the permeability of the brain endothelial cells by interacting with caveolin-1 and triggering caveolin-1 intracellular trafficking.

    PubMed

    Song, Yang; Wang, Ping; Ma, Jun; Xue, Yixue

    2014-06-01

    The blood-tumor barrier (BTB) significantly limits the delivery of chemotherapeutic drugs to brain tumors. In this study, we found a significant increase in the permeability of BTB by mediating the association of the C-terminus of alpha subunit of human large-conductance calcium-activated potassium channels (hSlo1c) with caveolin-1 (Cav-1). We present evidence for the first time that hSlo1c associates with Cav-1 in human brain microvascular endothelial cells (HBMECs). A 57-amino acid (966-1022) fragment in hSlo1c was identified to be critical for hSlo1c/Cav-1 interaction. Activation of HBMECs transfected with fusion plasmids of pCMV-hSlo1c containing aa966-1022 by NS1619 selectively enhanced BTB permeability in a BTB model from the co-culture of HBMECs and U87 MG cells but not if the fusion plasmid lacks this fragment. This effect was attenuated by filipin, an agent disrupting caveolae or deletion of the potential interaction fragment, suggesting hSlo1c/Cav-1 association is crucial for regulating the permeability of BTB. Furthermore, we found that hSlo1c/Cav-1 association boosted Cav-1 transferring from the cell membrane to the cytoplasm of HBMECs. Our study indicates that cytoplasmic hSlo1c not only associates with Cav-1 but also has functional consequences on the permeability of BTB by triggering the intracellular trafficking of its interacting protein partner, Cav-1.

  6. Caveolin-1 is a Modulator of Fibroblast Activation and a Potential Biomarker for Gastric Cancer

    PubMed Central

    Shen, Xiao-Jun; Zhang, Hao; Tang, Gu-Sheng; Wang, Xu-Dong; Zheng, Rui; Wang, Yang; Zhu, Yan; Xue, Xu-Chao; Bi, Jian-Wei

    2015-01-01

    Stromal fibroblasts play an important role in chronic cancer-related inflammation and the development as well as progression of malignant diseases. However, the difference and relationship between inflammation-associated fibroblasts (IAFs) and cancer-associated fibroblasts (CAFs) are poorly understood. In this study, gastric cancer-associated fibroblasts (GCAFs) and their corresponding inflammation-associated fibroblasts (GIAFs) were isolated from gastric cancer (GC) with chronic gastritis and cultured in vitro. These activated fibroblasts exhibited distinct secretion and tumor-promoting behaviors in vitro. Using proteomics and bioinformatics techniques, caveolin-1 (Cav-1) was identified as a major network-centric protein of a sub-network consisting of 121 differentially expressed proteins between GIAFs and GCAFs. Furthermore, immunohistochemistry in a GC cohort showed significant difference in Cav-1 expression score between GIAFs and GCAFs and among patients with different grades of chronic gastritis. Moreover, silencing of Cav-1 in GIAFs and GCAFs using small interfering RNA increased the production of pro-inflammatory and tumor-enhancing cytokines and chemokines in conditioned mediums that elevated cell proliferation and migration when added to GC cell lines AGS and MKN45 in vitro. In addition, Cav-1 status in GIAFs and GCAFs independently predicted the prognosis of GC. Our findings indicate that Cav-1 loss contributes to the distinct activation statuses of fibroblasts in GC microenvironment and gastritis mucosa, and Cav-1 expression in both GCAFs and GIAFs may serve as a potential biomarker for GC progression. PMID:25798057

  7. Caveolin-1-LRP6 signaling module stimulates aerobic glycolysis in prostate cancer.

    PubMed

    Tahir, Salahaldin A; Yang, Guang; Goltsov, Alexei; Song, Ki-Duk; Ren, Chengzhen; Wang, Jianxiang; Chang, Wenjun; Thompson, Timothy C

    2013-03-15

    Caveolin 1 (Cav-1) is a plasma membrane-associated protein with the capacity to modulate signaling activities in a context-dependent fashion. Interactions between Cav-1 and low-density lipoprotein receptor-related protein 6 (LRP6) were reported to be important for the regulation of Wnt-β-catenin (β-cat) signaling. Cav-1 also interacts with insulin and IGF-I receptors (IGF-IR/IR) and can stimulate IR kinase activities. We found positive correlation between Cav-1 and LRP6 expression in both human primary prostate cancer and metastasis tissues and in PC-3 cells. Cav-1 stimulation of Wnt-β-cat signaling and c-Myc levels was positively associated with LRP6 expression in LNCaP, PC-3, and DU145 prostate cancer cells. Importantly, LRP6 and, to a lesser extent, Cav-1 were found to stimulate aerobic glycolysis. These activities were positively associated with the expression of HK2 and Glut3 and shown to be dependent on Akt signaling by both gene knockdown and chemical inhibition methods. We further showed that Cav-1 and LRP6 exert their effects on Akt and glycolytic activities by stimulating IGF-IR/IR signaling. Overall, our results show that Cav-1 interacts with LRP6 to generate an integrated signaling module that leads to the activation of IGF-IR/IR and results in stimulation of Akt-mTORC1 signaling and aerobic glycolysis in prostate cancer.

  8. Caveolin-1–LRP6 Signaling Module Stimulates Aerobic Glycolysis in Prostate Cancer

    PubMed Central

    Tahir, Salahaldin A.; Yang, Guang; Goltsov, Alexei; Song, Ki-Duk; Ren, Chengzhen; Wang, Jianxiang; Chang, Wenjun; Thompson, Timothy C.

    2013-01-01

    Caveolin 1 (Cav-1) is a plasma membrane–associated protein with the capacity to modulate signaling activities in a context-dependent fashion. Interactions between Cav-1 and low-density lipoprotein receptor–related protein 6 (LRP6) were reported to be important for the regulation of Wnt-β-catenin (β-cat) signaling. Cav-1 also interacts with insulin and IGF-I receptors (IGF-IR/IR) and can stimulate IR kinase activities. We found positive correlation between Cav-1 and LRP6 expression in both human primary prostate cancer and metastasis tissues and in PC-3 cells. Cav-1 stimulation of Wnt–β-cat signaling and c-Myc levels was positively associated with LRP6 expression in LNCaP, PC-3, and DU145 prostate cancer cells. Importantly, LRP6 and, to a lesser extent, Cav-1 were found to stimulate aerobic glycolysis. These activities were positively associated with the expression of HK2 and Glut3 and shown to be dependent on Akt signaling by both gene knockdown and chemical inhibition methods. We further showed that Cav-1 and LRP6 exert their effects on Akt and glycolytic activities by stimulating IGF-IR/IR signaling. Overall, our results demonstrate that Cav-1 interacts with LRP6 to generate an integrated signaling module that leads to the activation of IGF-IR/IR and results in stimulation of Akt–mTORC1 signaling and aerobic glycolysis in prostate cancer. PMID:23302227

  9. Caveolin-1 modulates intraocular pressure: implications for caveolae mechanoprotection in glaucoma

    PubMed Central

    Elliott, Michael H.; Ashpole, Nicole E.; Gu, Xiaowu; Herrnberger, Leonie; McClellan, Mark E.; Griffith, Gina L.; Reagan, Alaina M.; Boyce, Timothy M.; Tanito, Masaki; Tamm, Ernst R.; Stamer, W. Daniel

    2016-01-01

    Polymorphisms in the CAV1/2 genes that encode signature proteins of caveolae are associated with glaucoma, the second leading cause of blindness worldwide, and with its major risk factor, intraocular pressure (IOP). We hypothesized that caveolin-1 (Cav-1) participates in IOP maintenance via modulation of aqueous humor drainage from the eye. We localize caveolae proteins to human and murine conventional drainage tissues and show that caveolae respond to mechanical stimulation. We show that Cav-1-deficient (Cav-1−/−) mice display ocular hypertension explained by reduced pressure-dependent drainage of aqueous humor. Cav-1 deficiency results in loss of caveolae in the Schlemm’s canal (SC) and trabecular meshwork. However, their absence did not appear to impact development nor adult form of the conventional outflow tissues according to rigorous quantitative ultrastructural analyses, but did affect cell and tissue behavior. Thus, when IOP is experimentally elevated, cells of the Cav-1−/− outflow tissues are more susceptible to plasma membrane rupture indicating that caveolae play a role in mechanoprotection. Additionally, aqueous drainage from Cav-1−/− eyes was more sensitive to nitric oxide (NO) synthase inhibition than controls, suggesting that excess NO partially compensates for outflow pathway dysfunction. These results provide a functional link between a glaucoma risk gene and glaucoma-relevant pathophysiology. PMID:27841369

  10. Caveolin-1 Regulates Endothelial Adhesion of Lung Cancer Cells via Reactive Oxygen Species-Dependent Mechanism

    PubMed Central

    Chanvorachote, Pithi; Chunhacha, Preedakorn

    2013-01-01

    The knowledge regarding the role of caveolin-1 (Cav-1) protein on endothelium adhesion of cancer cells is unclear. The present study revealed that Cav-1 plays a negative regulatory role on cancer-endothelium interaction. Endogenous Cav-1 was shown to down-regulate during cell detachment and the level of such a protein was conversely associated with tumor-endothelial adhesion. Furthermore, the ectopic overexpression of Cav-1 attenuated the ability of the cancer cells to adhere to endothelium while shRNA-mediated Cav-1 knock-down exhibited the opposite effect. We found that cell detachment increased cellular hydrogen peroxide and hydroxyl radical generation and such reactive oxygen species (ROS) were responsible for the increasing interaction between cancer cells and endothelial cells through vascular endothelial cell adhesion molecule-1 (VCAM-1). Importantly, Cav-1 was shown to suppress hydrogen peroxide and hydroxyl radical formation by sustaining the level of activated Akt which was critical for the role of Cav-1 in attenuating the cell adhesion. Together, the present study revealed the novel role of Cav-1 and underlying mechanism on tumor adhesion which explain and highlight an important role of Cav-1 on lung cancer cell metastasis. PMID:23460862

  11. Caveolin-1 regulates TCR signal strength and regulatory T-cell differentiation into alloreactive T cells.

    PubMed

    Schönle, Anne; Hartl, Frederike A; Mentzel, Jan; Nöltner, Theresa; Rauch, Katharina S; Prestipino, Alessandro; Wohlfeil, Sebastian A; Apostolova, Petya; Hechinger, Anne-Kathrin; Melchinger, Wolfgang; Fehrenbach, Kerstin; Guadamillas, Marta C; Follo, Marie; Prinz, Gabriele; Ruess, Ann-Katrin; Pfeifer, Dietmar; del Pozo, Miguel Angel; Schmitt-Graeff, Annette; Duyster, Justus; Hippen, Keli I; Blazar, Bruce R; Schachtrup, Kristina; Minguet, Susana; Zeiser, Robert

    2016-04-14

    Caveolin-1 (Cav-1) is a key organizer of membrane specializations and a scaffold protein that regulates signaling in multiple cell types. We found increased Cav-1 expression in human and murine T cells after allogeneic hematopoietic cell transplantation. Indeed, Cav-1(-/-)donor T cells caused less severe acute graft-versus-host disease (GVHD) and yielded higher numbers of regulatory T cells (Tregs) compared with controls. Depletion of Tregs from the graft abrogated this protective effect. Correspondingly, Treg frequencies increased when Cav-1(-/-)T cells were exposed to transforming growth factor-β/T-cell receptor (TCR)/CD28 activation or alloantigen stimulation in vitro compared with wild-type T cells. Mechanistically, we found that the phosphorylation of Cav-1 is dispensable for the control of T-cell fate by using a nonphosphorylatable Cav-1 (Y14F/Y14F) point-mutation variant. Moreover, the close proximity of lymphocyte-specific protein tyrosine kinase (Lck) to the TCR induced by TCR-activation was reduced in Cav-1(-/-)T cells. Therefore, less TCR/Lck clustering results in suboptimal activation of the downstream signaling events, which correlates with the preferential development into a Treg phenotype. Overall, we report a novel role for Cav-1 in TCR/Lck spatial distribution upon TCR triggering, which controls T-cell fate toward a regulatory phenotype. This alteration translated into a significant increase in the frequency of Tregs and reduced GVHD in vivo.

  12. Akt phosphorylates and regulates Pdcd4 tumor suppressor protein.

    PubMed

    Palamarchuk, Alexey; Efanov, Alexey; Maximov, Vadim; Aqeilan, Rami I; Croce, Carlo M; Pekarsky, Yuri

    2005-12-15

    Programmed cell death 4 (Pdcd4) is a tumor suppressor protein that interacts with eukaryotic initiation factor 4A and inhibits protein synthesis. Pdcd4 also suppresses the transactivation of activator protein-1 (AP-1)-responsive promoters by c-Jun. The Akt (protein kinase B) serine/threonine kinase is a key mediator of phosphoinositide 3-kinase pathway involved in the regulation of cell proliferation, survival, and growth. Because Pdcd4 has two putative Akt phosphorylation sites at Ser(67) and Ser(457), we investigated whether Akt phosphorylates and regulates Pdcd4. Our results show that Akt specifically phosphorylates Ser(67) and Ser(457) residues of Pdcd4 in vitro and in vivo. We further show that phosphorylation of Pdcd4 by Akt causes nuclear translocation of Pdcd4. Using luciferase assay, we show that phosphorylation of Pdcd4 by Akt also causes a significant decrease of the ability of Pdcd4 to interfere with the transactivation of AP-1-responsive promoter by c-Jun.

  13. PML tumor suppressor protein is required for HCV production

    SciTech Connect

    Kuroki, Misao; Ariumi, Yasuo; Hijikata, Makoto; Ikeda, Masanori; Dansako, Hiromichi; Wakita, Takaji; Shimotohno, Kunitada; Kato, Nobuyuki

    2013-01-11

    Highlights: Black-Right-Pointing-Pointer PML tumor suppressor protein is required for HCV production. Black-Right-Pointing-Pointer PML is dispensable for HCV RNA replication. Black-Right-Pointing-Pointer HCV could not alter formation of PML-NBs. Black-Right-Pointing-Pointer INI1 and DDX5, PML-related proteins, are involved in HCV life cycle. -- Abstract: PML tumor suppressor protein, which forms discrete nuclear structures termed PML-nuclear bodies, has been associated with several cellular functions, including cell proliferation, apoptosis and antiviral defense. Recently, it was reported that the HCV core protein colocalizes with PML in PML-NBs and abrogates the PML function through interaction with PML. However, role(s) of PML in HCV life cycle is unknown. To test whether or not PML affects HCV life cycle, we examined the level of secreted HCV core and the infectivity of HCV in the culture supernatants as well as the level of HCV RNA in HuH-7-derived RSc cells, in which HCV-JFH1 can infect and efficiently replicate, stably expressing short hairpin RNA targeted to PML. In this context, the level of secreted HCV core and the infectivity in the supernatants from PML knockdown cells was remarkably reduced, whereas the level of HCV RNA in the PML knockdown cells was not significantly affected in spite of very effective knockdown of PML. In fact, we showed that PML is unrelated to HCV RNA replication using the subgenomic HCV-JFH1 replicon RNA, JRN/3-5B. Furthermore, the infectivity of HCV-like particle in the culture supernatants was significantly reduced in PML knockdown JRN/3-5B cells expressing core to NS2 coding region of HCV-JFH1 genome using the trans-packaging system. Finally, we also demonstrated that INI1 and DDX5, the PML-related proteins, are involved in HCV production. Taken together, these findings suggest that PML is required for HCV production.

  14. Single epicardial cell transcriptome sequencing identifies Caveolin 1 as an essential factor in zebrafish heart regeneration

    PubMed Central

    Cao, Jingli; Navis, Adam; Cox, Ben D.; Dickson, Amy L.; Gemberling, Matthew; Karra, Ravi; Bagnat, Michel; Poss, Kenneth D.

    2016-01-01

    In contrast to mammals, adult zebrafish have a high capacity to regenerate damaged or lost myocardium through proliferation of cardiomyocytes spared from damage. The epicardial sheet covering the heart is activated by injury and aids muscle regeneration through paracrine effects and as a multipotent cell source, and has received recent attention as a target in cardiac repair strategies. Although it is recognized that epicardium is required for muscle regeneration and itself has high regenerative potential, the extent of cellular heterogeneity within epicardial tissue is largely unexplored. Here, we performed transcriptome analysis on dozens of epicardial lineage cells purified from zebrafish harboring a transgenic reporter for the pan-epicardial gene tcf21. Hierarchical clustering analysis suggested the presence of at least three epicardial cell subsets defined by expression signatures. We validated many new pan-epicardial and epicardial markers by alternative expression assays. Additionally, we explored the function of the scaffolding protein and main component of caveolae, caveolin 1 (cav1), which was present in each epicardial subset. In BAC transgenic zebrafish, cav1 regulatory sequences drove strong expression in ostensibly all epicardial cells and in coronary vascular endothelial cells. Moreover, cav1 mutant zebrafish generated by genome editing showed grossly normal heart development and adult cardiac anatomy, but displayed profound defects in injury-induced cardiomyocyte proliferation and heart regeneration. Our study defines a new platform for the discovery of epicardial lineage markers, genetic tools, and mechanisms of heart regeneration. PMID:26657776

  15. Is There a Potential Therapeutic Role for Caveolin-1 in Fibrosis?

    PubMed

    Shihata, Waled A; Putra, Mohammad R A; Chin-Dusting, Jaye P F

    2017-01-01

    Fibrosis is a process of dysfunctional wound repair, described by a failure of tissue regeneration and excessive deposition of extracellular matrix, resulting in tissue scarring and subsequent organ deterioration. There are a broad range of stimuli that may trigger, and exacerbate the process of fibrosis, which can contribute to the growing rates of morbidity and mortality. Whilst the process of fibrosis is widely described and understood, there are no current standard treatments that can reduce or reverse the process effectively, likely due to the continuing knowledge gaps surrounding the cellular mechanisms involved. Several cellular targets have been implicated in the regulation of the fibrotic process including membrane domains, ion channels and more recently mechanosensors, specifically caveolae, particularly since these latter contain various signaling components, such as members of the TGFβ and MAPK/ERK signaling pathways, all of which are key players in the process of fibrosis. This review explores the anti-fibrotic influences of the caveola, and in particular the key underpinning protein, caveolin-1, and its potential as a novel therapeutic target.

  16. Is There a Potential Therapeutic Role for Caveolin-1 in Fibrosis?

    PubMed Central

    Shihata, Waled A.; Putra, Mohammad R. A.; Chin-Dusting, Jaye P. F.

    2017-01-01

    Fibrosis is a process of dysfunctional wound repair, described by a failure of tissue regeneration and excessive deposition of extracellular matrix, resulting in tissue scarring and subsequent organ deterioration. There are a broad range of stimuli that may trigger, and exacerbate the process of fibrosis, which can contribute to the growing rates of morbidity and mortality. Whilst the process of fibrosis is widely described and understood, there are no current standard treatments that can reduce or reverse the process effectively, likely due to the continuing knowledge gaps surrounding the cellular mechanisms involved. Several cellular targets have been implicated in the regulation of the fibrotic process including membrane domains, ion channels and more recently mechanosensors, specifically caveolae, particularly since these latter contain various signaling components, such as members of the TGFβ and MAPK/ERK signaling pathways, all of which are key players in the process of fibrosis. This review explores the anti-fibrotic influences of the caveola, and in particular the key underpinning protein, caveolin-1, and its potential as a novel therapeutic target. PMID:28970796

  17. Caveolin-1 and ATP binding cassette transporter A1 and G1-mediated cholesterol efflux.

    PubMed

    Wang, Faqi; Gu, Hong-mei; Zhang, Da-wei

    2014-01-01

    Atherosclerosis is one major cause of cardiovascular diseases, the leading cause of death in industrialized countries. Reverse cholesterol transport (RCT) is thought to be one primary pathway to protect against atherosclerosis. The first and rate-limiting step of RCT is ATP-binding cassette transport A1 (ABCA1) and ABCG1-mediated cholesterol efflux from the cells. Recently, caveolin-1 (CAV1), a scaffolding protein that organizes and concentrates certain caveolin-interacting signaling molecules and receptors within caveolae membranes, has been shown to regulate ABCA1 and ABCG1-mediated cholesterol efflux probably via interacting with them. In the present review, we summarize the current knowledge and views on the regulatory role of CAV1 on the cholesterol homeostasis with emphasis on the association of CAV1 with ABCA1 and ABCG1. We conclude that the dominance of the positive regulation by CAV1 on the ABCA1 and ABCG1-mediated cholesterol efflux is depending on the species, cell types, as well as the levels of CAV1 expression.

  18. Reciprocal Activating Crosstalk between c-Met and Caveolin 1 Promotes Invasive Phenotype in Hepatocellular Carcinoma

    PubMed Central

    Korhan, Peyda; Erdal, Esra; Kandemiş, Emine; Çokaklı, Murat; Nart, Deniz; Yılmaz, Funda; Can, Alp; Atabey, Neşe

    2014-01-01

    c-Met, the receptor for Hepatocyte Growth Factor (HGF), overexpressed and deregulated in Hepatocellular Carcinoma (HCC). Caveolin 1 (CAV1), a plasma membrane protein that modulates signal transduction molecules, is also overexpressed in HCC. The aim of this study was to investigate biological and clinical significance of co-expression and activation of c-Met and CAV1 in HCC. We showed that c-Met and CAV1 were co-localized in HCC cells and HGF treatment increased this association. HGF-triggered c-Met activation caused a concurrent rise in both phosphorylation and expression of CAV1. Ectopic expression of CAV1 accelerated c-Met signaling, resulted in enhanced migration, invasion, and branching-morphogenesis. Silencing of CAV1 downregulated c-Met signaling, and decreased migratory/invasive capability of cells and attenuated branching morphogenesis. In addition, activation and co-localization of c-Met and CAV1 were elevated during hepatocarcinogenesis. In conclusion reciprocal activating crosstalk between c-Met and CAV1 promoted oncogenic signaling of c-Met contributed to the initiation and progression of HCC. PMID:25148256

  19. Caveolin-1 Promotes the Imbalance of Th17/Treg in Patients with Chronic Obstructive Pulmonary Disease.

    PubMed

    Sun, Nina; Wei, Xiaofang; Wang, Jingluan; Cheng, Zhaozhong; Sun, Weihong

    2016-12-01

    The imbalance of Th17/Treg cells plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Caveolin-1 (Cav-1) has been regarded as a potential critical regulatory protein in pathological mechanisms of chronic inflammatory respiratory diseases. Therefore, we investigated whether the loss of Cav-1 is involved in the homeostasis of Th17/Treg cells in COPD. We examined the expressions of plasma Cav-1 and circulating Th17, Treg cells, and the related cytokines in patients with COPD. Enzyme-linked immunosorbent assay (ELISA) analyses showed a significant reduction of plasma Cav-1 levels in patients with stable COPD (SCOPD) and acutely exacerbated COPD (AECOPD) compared to smokers without COPD. This loss was associated with an increase in frequency of Treg and decreased in frequency of Th17 cells. To further identify the role of Cav-1, we studied the effects of Cav-1 overexpression or downregulation on frequencies of Treg and Th17 cells in peripheral blood mononuclear cells (PBMCs) from subjects. Interestingly, small interfering RNA (siRNA) downregulation of Cav-1 was accompanied by an augmentation of Treg and reduction of Th17 expression. Together, our study demonstrated that the loss of Cav-1 contributed to the imbalance of Th17/Treg cells in patients with COPD.

  20. Caveolin-1 regulates genomic action of the glucocorticoid receptor in neural stem cells.

    PubMed

    Peffer, Melanie E; Chandran, Uma R; Luthra, Soumya; Volonte, Daniela; Galbiati, Ferruccio; Garabedian, Michael J; Monaghan, A Paula; DeFranco, Donald B

    2014-07-01

    While glucocorticoids (GCs) are used clinically to treat many conditions, their neonatal and prenatal usage is increasingly controversial due to reports of delayed adverse outcomes, especially their effects on brain development. Such alterations may reflect the impact of GCs on neural progenitor/stem cell (NPSC) function. We previously demonstrated that the lipid raft protein caveolin-1 (Cav-1) was required for rapid GC signaling in embryonic mouse NPSCs operating through plasma membrane-bound glucocorticoid receptors (GRs). We show here that genomic GR signaling in NPSCs requires Cav-1. Loss of Cav-1 impacts the transcriptional response of many GR target genes (e.g., the serum- and glucocorticoid-regulated kinase 1 gene) that are likely to mediate the antiproliferative effects of GCs. Microarray analysis of wild-type C57 or Cav-1-deficient NPSCs identified approximately 100 genes that are differentially regulated by GC treatment. These changes in hormone responsiveness in Cav-1 knockout NPSCs are associated with the loss of GC-regulated phosphorylation of GR at serine 211 but not at serine 226. Chromatin recruitment of total GR to regulatory regions of target genes such as Fkbp-5, RhoJ, and Sgk-1, as well as p211-GR recruitment to Sgk-1, are compromised in Cav-1 knockout NPSCs. Cav-1 is therefore a multifunctional regulator of GR in NPSCs influencing both rapid and genomic action of the receptor to impact cell proliferation.

  1. Expression of Caveolin 1 is enhanced by DNA demethylation during adipocyte differentiation. status of insulin signaling.

    PubMed

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Milagro, Fermín Ignacio; Martínez, José Alfredo; de Miguel, Carlos

    2014-01-01

    Caveolin 1 (Cav-1) is an essential constituent of adipocyte caveolae which binds the beta subunit of the insulin receptor (IR) and is implicated in the regulation of insulin signaling. We have found that, during adipocyte differentiation of 3T3-L1 cells the promoter, exon 1 and first intron of the Cav-1 gene undergo a demethylation process that is accompanied by a strong induction of Cav-1 expression, indicating that epigenetic mechanisms must have a pivotal role in this differentiation process. Furthermore, IR, PKB-Akt and Glut-4 expression are also increased during the differentiation process suggesting a coordinated regulation with Cav-1. Activation of Cav-1 protein by phosphorylation arises during the differentiation process, yet in fully mature adipocytes insulin is no longer able to significantly increase Cav-1 phosphorylation. However, these long-term differentiated cells are still able to respond adequately to insulin, increasing IR and PKB-Akt phosphorylation and glucose uptake. The activation of Cav-1 during the adipocyte differentiation process could facilitate the maintenance of insulin sensitivity by these fully mature adipocytes isolated from additional external stimuli. However, under the influence of physiological conditions associated to obesity, such as chronic inflammation and hypoxia, insulin sensitivity would finally be compromised.

  2. Expression of Caveolin 1 Is Enhanced by DNA Demethylation during Adipocyte Differentiation. Status of Insulin Signaling

    PubMed Central

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Milagro, Fermín Ignacio; Martínez, José Alfredo; de Miguel, Carlos

    2014-01-01

    Caveolin 1 (Cav-1) is an essential constituent of adipocyte caveolae which binds the beta subunit of the insulin receptor (IR) and is implicated in the regulation of insulin signaling. We have found that, during adipocyte differentiation of 3T3-L1 cells the promoter, exon 1 and first intron of the Cav-1 gene undergo a demethylation process that is accompanied by a strong induction of Cav-1 expression, indicating that epigenetic mechanisms must have a pivotal role in this differentiation process. Furthermore, IR, PKB-Akt and Glut-4 expression are also increased during the differentiation process suggesting a coordinated regulation with Cav-1. Activation of Cav-1 protein by phosphorylation arises during the differentiation process, yet in fully mature adipocytes insulin is no longer able to significantly increase Cav-1 phosphorylation. However, these long-term differentiated cells are still able to respond adequately to insulin, increasing IR and PKB-Akt phosphorylation and glucose uptake. The activation of Cav-1 during the adipocyte differentiation process could facilitate the maintenance of insulin sensitivity by these fully mature adipocytes isolated from additional external stimuli. However, under the influence of physiological conditions associated to obesity, such as chronic inflammation and hypoxia, insulin sensitivity would finally be compromised. PMID:24751908

  3. Caveolin-1 Secreted from Adipose Tissues and Adipocytes Functions as an Adipogenesis Enhancer.

    PubMed

    Chang, Chia-Chu; Chen, Chen-Yu; Wen, Hui-Chin; Huang, Chih-Yang; Hung, Ming-Shiu; Lu, Hsi-Chi; Chen, Woan-Ling; Chang, Chung-Ho

    2017-09-25

    Caveolin-1 (Cav-1) is expressed abundantly in adipose tissue and involved in many physiological processes. While Cav-1 has been reported to be secreted in pancreatic acinar cells and LNCaP prostate cancer cells, its secretion from adipose tissue awaits investigation. Cav-1 secretion from 3T3-L1 adipocytes and fat tissues from normal chow diet- and high-fat diet (HFD)-fed mice was measured. Functions and uptake of secreted Cav-1 proteins were assessed by adding Cav-1 back to preadipocytes and LNCaP cells. Cav-1 secretion was evident in adipose tissues and were substantially promoted in HFD-fed mice. Cav-1 was detectable in the conditioned media of 3T3-L1 adipocytes but not preadipocytes. Hypertrophied adipocytes induced by glucose and fatty acids secreted more Cav-1, suggesting that hypertrophied adipocytes were responsible for enhanced Cav-1 secretion in obese mice. Secreted Cav-1 was taken up by preadipocytes and LNCaP cells. 3T3-L1 preadipocytes overexpressing Cav-1 were better differentiated, suggesting that secreted Cav-1 may promote adipogenesis. Hypertrophied 3T3-L1 adipocytes enhanced ERK1/2 activation, and the attenuation of ERK1/2 activity by PD98059 inhibited Cav-1 secretion. Cav-1 is actively secreted from adipocytes as a putative adipogenesis enhancer. Hypertrophied adipocytes secrete Cav-1 via ERK1/2-dependent mechanisms to promote adipogenesis, thus establishing a vicious cycle. © 2017 The Obesity Society.

  4. Pro-metastatic NEDD9 regulates individual cell migration via caveolin-1-dependent trafficking of integrins

    PubMed Central

    Kozyulina, Polina Y.; Loskutov, Yuriy V.; Kozyreva, Varvara K.; Rajulapati, Anuradha; Ice, Ryan J.; Jones, Brandon. C.; Pugacheva, Elena N.

    2014-01-01

    The dissemination of tumor cells relies on efficient cell adhesion and migration, which in turn depends upon endocytic trafficking of integrins. In the current work, it was found that depletion of pro-metastatic protein, NEDD9, in breast cancer (BC) cells results in a significant decrease in individual cell migration due to impaired trafficking of ligand-bound integrins. NEDD9 deficiency does not affect the expression or internalization of integrins but heightens caveolae-dependent trafficking of ligand-bound integrins to early endosomes. Increase in mobility of ligand-bound integrins is concomitant with an increase in tyrosine phosphorylation of caveolin-1 (CAV1) and volume of CAV1-vesicles. NEDD9 directly binds to CAV1 and co-localizes within CAV1 vesicles. In the absence of NEDD9, the trafficking of ligand-bound integrins from early to late endosomes is impaired, resulting in a significant decrease in degradation of ligand/integrin complexes and an increase in recycling of ligand-bound integrins from early endosomes back to the plasma membrane without ligand disengagement, thus leading to low adhesion and migration. Re-expression of NEDD9 or decrease in the amount of active, tyrosine 14 phosphorylated (Tyr14) CAV1 in NEDD9 depleted cells rescues the integrin trafficking deficiency and restores cellular adhesion and migration capacity. Collectively, these findings indicate that NEDD9 orchestrates trafficking of ligand-bound integrins through the attenuation of CAV1 activity. PMID:25319010

  5. DT(270-326) , a Truncated Diphtheria Toxin, Increases Blood-Tumor Barrier Permeability by Upregulating the Expression of Caveolin-1.

    PubMed

    Lin, Yang; Wang, Ping; Liu, Yun-Hui; Shang, Xiu-Li; Chen, Liang-Yu; Xue, Yi-Xue

    2016-06-01

    The nontoxic mutant of diphtheria toxin (DT) has been demonstrated to act as a receptor-specific carrier protein to delivery drug into brain. Recent research showed that the truncated "receptorless" DT was still capable of being internalized into cells. This study investigated the effects and potential mechanisms of DT(270-326) , a truncated "receptorless" DT, on the permeability of the blood-tumor barrier (BTB). BTB and GECs were subjected to DT(270-326) treatment. HRP flux assays, immunofluorescent, co-immunoprecipitation, Western blot, CCK-8, and Flow cytometry analysis were used to evaluate the effects of DT(270-326) administration. Our results revealed that 5 μM of DT(270-326) significantly increased the permeability of BTBin vitro, which reached its peak at 6 h. The permeability was reduced by pretreatment with filipinIII. DT(270-326) co-localized and interacted with caveolin-1 via its caveolin-binding motif. The mRNA and protein expression levels of caveolin-1 were identical with the changes of BTB permeability. The upregulated expression of caveolin-1 was associated with Src kinase-dependent tyrosine phosphorylation of caveolin-1, which subsequently induced phosphorylation and inactivation of the transcription factor Egr-1. The combination of DT(270-326) with doxorubicin significantly enhanced the loss of cell viability and apoptosis of U87 glioma cells in contrast to doxorubicin alone. DT(270-326) might provide a novel strategy to increase the delivery of macromolecular therapeutic agents across the BTB. © 2016 John Wiley & Sons Ltd.

  6. Cellular Factor XIIIA Transglutaminase Localizes in Caveolae and Regulates Caveolin-1 Phosphorylation, Homo-oligomerization and c-Src Signaling in Osteoblasts

    PubMed Central

    Wang, Shuai; Kaartinen, Mari T.

    2015-01-01

    Transglutaminases (TGs) are a family of widely distributed enzymes that catalyze protein crosslinking by forming a covalent isopeptide bond between the substrate proteins. We have shown that MC3T3-E1 osteoblasts express Factor XIII-A (FXIII-A), and that the extracellular crosslinking activity of FXIII-A is involved in regulating matrix secretion and deposition. In this study, we have investigated the localization and potential role of intracellular FXIII-A. Conventional immunofluorescence microscopy and TIRF microscopy analyses showed that FXIII-A co-localizes with caveolin-1 in specialized membrane structures, caveolae, in differentiating osteoblasts. The caveolae-disrupting agent methyl-β-cyclodextrin abolished FXIII-A staining and co-localization with caveolin-1 from the osteoblast plasma membrane. The presence of FXIII-A in caveolae was confirmed by preparing caveolae-enriched cellular fractions using sucrose density gradient ultracentrifugation followed by western blotting. Despite this association of FXIII-A with caveolae, there was no detectable transglutaminase activity in caveolae, as measured by monodansylcadaverine incorporation. TG inhibitor NC9—which can alter TG enzyme conformation—localized to caveolae and displaced FXIII-A from these structures when added to the osteoblast cultures. The decreased FXIII-A levels in caveolae after NC9 treatment increased c-Src activation, which resulted in caveolin-1 phosphorylation, homo-oligomerization and Akt phosphorylation, suggesting cellular FXIII-A has a role in regulating c-Src signaling in osteoblasts. PMID:26231113

  7. Hyperglycemia and downregulation of caveolin-1 enhance neuregulin-induced demyelination.

    PubMed

    Yu, Cuijuan; Rouen, Shefali; Dobrowsky, Rick T

    2008-06-01

    Neuregulins (NRGs) are growth factors which bind to Erb receptor tyrosine kinases that localize to Schwann cells (SCs). Although NRGs can promote cell survival, mitogenesis, and myelination in undifferentiated SCs, they also induce demyelination of myelinated co-cultures of SCs and dorsal root ganglion (DRG) neurons. We have shown previously that Erb B2 activity increased in premyelinating SCs in response to hyperglycemia, and that this correlated with the downregulation of the protein caveolin-1 (Cav-1). As myelinated SCs undergo substantial degeneration in diabetic neuropathy, we used myelinated SC/DRG neuron co-cultures to determine if hyperglycemia and changes in Cav-1 expression could enhance NRG-induced demyelination. In basal glucose, NRG1 caused a 2.4-fold increase in the number of damaged myelin segments. This damage reached 3.8-fold under hyperglycemic conditions, and was also associated with a robust decrease in the expression of Cav-1 and compact myelin proteins. The loss of Cav-1 and compact myelin proteins following hyperglycemia and NRG treatment was not due to neuronal loss, since the axons remained intact and there was no loss of PGP 9.5, an axonal marker protein. To examine if changes in Cav-1 were sufficient to alter the extent of NRG-induced demyelination, SC/DRG neurons co-cultures were infected with antisense or dominant-negative Cav-1(P132L) adenoviruses. Either antisense-mediated downregulation or mis-localization of endogenous Cav-1 by Cav-1(P132L) resulted in a 1.5- to 2.4-fold increase in NRG-induced degeneration compared to that present in control cultures. These data support that hyperglycemia and changes in Cav-1 are sufficient to sensitize myelinated SC/DRG co-cultures to NRG-induced demyelination. Copyright (c) 2008 Wiley-Liss, Inc.

  8. Hyperglycemia and Downregulation of Caveolin-1 Enhance Neuregulin-Induced Demyelination

    PubMed Central

    YU, CUIJUAN; ROUEN, SHEFALI; DOBROWSKY, RICK T.

    2008-01-01

    Neuregulins (NRGs) are growth factors which bind to Erb receptor tyrosine kinases that localize to Schwann cells (SCs). Although NRGs can promote cell survival, mitogenesis, and myelination in undifferentiated SCs, they also induce demyelination of myelinated co-cultures of SCs and dorsal root ganglion (DRG) neurons. We have shown previously that Erb B2 activity increased in premyelinating SCs in response to hyperglycemia, and that this correlated with the downregulation of the protein caveolin-1 (Cav-1). As myelinated SCs undergo substantial degeneration in diabetic neuropathy, we used myelinated SC/DRG neuron co-cultures to determine if hyperglycemia and changes in Cav-1 expression could enhance NRG-induced demyelination. In basal glucose, NRG1 caused a 2.4-fold increase in the number of damaged myelin segments. This damage reached 3.8-fold under hyperglycemic conditions, and was also associated with a robust decrease in the expression of Cav-1 and compact myelin proteins. The loss of Cav-1 and compact myelin proteins following hyperglycemia and NRG treatment was not due to neuronal loss, since the axons remained intact and there was no loss of PGP 9.5, an axonal marker protein. To examine if changes in Cav-1 were sufficient to alter the extent of NRG-induced demyelination, SC/DRG neurons co-cultures were infected with antisense or dominant-negative Cav-1(P132L) adenoviruses. Either antisense-mediated downregulation or mis-localization of endogenous Cav-1 by Cav-1(P132L) resulted in a 1.5- to 2.4-fold increase in NRG-induced degeneration compared to that present in control cultures. These data support that hyperglycemia and changes in Cav-1 are sufficient to sensitize myelinated SC/DRG co-cultures to NRG-induced demyelination. PMID:18338795

  9. Hepatic caveolin-1 is enhanced in Cyp27a1/ApoE double knockout mice.

    PubMed

    Zurkinden, Line; Mansour, Yosef T; Rohrbach, Beatrice; Vogt, Bruno; Mistry, Hiten D; Escher, Geneviève

    2016-10-01

    Sterol 27-hydroxylase (CYP27A1) is involved in bile acid synthesis and cholesterol homoeostasis. Cyp27a1((-/-))/Apolipoprotein E((-/-)) double knockout mice (DKO) fed a western diet failed to develop atherosclerosis. Caveolin-1 (CAV-1), the main component of caveolae, is associated with lipid homoeostasis and has regulatory roles in vascular diseases. We hypothesized that liver CAV-1 would contribute to the athero-protective mechanism in DKO mice. Cyp27a1((+/+))/ApoE((-/-)) (ApoE KO), Cyp27a1((+/-))/ApoE((-/-)) (het), and DKO mice were fed a western diet for 2 months. Atherosclerotic plaque and CAV-1 protein were quantified in aortas. Hepatic Cav-1 mRNA was assessed using qPCR, CAV-1 protein by immunohistochemistry and western blotting. Total hepatic and plasma cholesterol was measured using chemiluminescence. Cholesterol efflux was performed in RAW264.7 cells, using mice plasma as acceptor. CAV-1 protein expression in aortas was increased in endothelial cells of DKO mice and negatively correlated with plaque surface (P < 0.05). In the liver, both CAV-1 protein and mRNA expression doubled in DKO, compared to ApoE KO and het mice (P < 0.001 for both) and was negatively correlated with total hepatic cholesterol (P < 0.05). Plasma from DKO, ApoE KO and het mice had the same efflux capacity. In the absence of CYP27A1, CAV-1 overexpression might have an additional athero-protective role by partly overcoming the defect in CYP27A1-mediated cholesterol efflux.

  10. Caveolin-1 contributes to realgar nanoparticle therapy in human chronic myelogenous leukemia K562 cells.

    PubMed

    Shi, Dan; Liu, Yan; Xi, Ronggang; Zou, Wei; Wu, Lijun; Zhang, Zhiran; Liu, Zhongyang; Qu, Chao; Xu, Baoli; Wang, Xiaobo

    Chronic myelogenous leukemia (CML) is characterized by the t(9;22) (q34;q11)-associated Bcr-Abl fusion gene, which is an essential element of clinical diagnosis. As a traditional Chinese medicine, realgar has been widely used for the treatment of various diseases for >1,500 years. Inspired by nano-drug, realgar nanoparticles (NPs) have been prepared with an average particle size of <100 nm in a previous work. Compared with coarse realgar, the realgar NPs have higher bioavailability. As a principal constituent protein of caveolae, caveolin-1 (Cav-1) participates in regulating various cellular physiological and pathological processes including tumorigenesis and tumor development. In previous studies, it was found that realgar NPs can inhibit several types of tumor cell proliferation. However, the therapeutic effect of realgar NPs on CML has not been fully elucidated. In the present paper, it was demonstrated that realgar NPs can inhibit the proliferation of K562 cells and degrade Bcr-Abl fusion protein effectively. Both apoptosis and autophagy were activated in a dose-dependent manner in realgar NPs treated cells, and the induction of autophagy was associated with class I phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway. Morphological analysis indicated that realgar NPs induced differentiation effectively in CML cells. Furthermore, it was identified that Cav-1 might play a crucial role in realgar NP therapy. In order to study the effects of Cav-1 on K562 cells during realgar NP treatment, a Cav-1 overexpression cell model was established by using transient transfection. The results indicated that Cav-1 overexpression inhibited K562 cell proliferation, promoted endogenic autophagy, and increased the sensitivity of K562 cells to realgar NPs. Therefore, the results demonstrated that realgar NPs degraded Bcr-Abl oncoprotein, while the underlying mechanism might be related to apoptosis and autophagy, and Cav-1 might be considered as a

  11. Caveolin-1 promotes Ewing sarcoma metastasis regulating MMP-9 expression through MAPK/ERK pathway

    PubMed Central

    Lagares-Tena, Laura; García-Monclús, Silvia; López-Alemany, Roser; Almacellas-Rabaiget, Olga; Huertas-Martínez, Juan; Sáinz-Jaspeado, Miguel; Mateo-Lozano, Silvia; Rodríguez-Galindo, Carlos; Rello-Varona, Santiago; Herrero-Martín, David; Tirado, Oscar M.

    2016-01-01

    Ewing sarcoma (ES) is a bone and soft tissue sarcoma affecting mostly children and young adults. Caveolin-1 (CAV1) is a well-known target of EWS/FLI1, the main driver of ES, with an oncogenic role in ES. We have previously described how CAV1 is able to induce metastasis in ES via matrix metalloproteinase-9 (MMP-9). In the present study we showed how CAV1 silencing in ES reduced MEK1/2 and ERK1/2 phosphorylation. Accordingly, chemical inhibition of MEK1/2 resulted in reduction in MMP-9 expression and activity that correlated with reduced migration and invasion. IQ Motif Containing GTPase Activating Protein 1 (IQGAP1) silencing reduced MEK1/2 and ERK1/2 phosphorylation and MMP-9 expression. Furthermore, IQGAP1 silenced cells showed a marked decrease in their migratory and invasive capacity. We demonstrated that CAV1 and IQGAP1 localize in close proximity at the cellular edge, thus IQGAP1 could be the connecting node between CAV1 and MEK/ERK in ES metastatic phenotype. Analysis of the phosphorylation profile of CAV1-silenced cells showed a decrease of p-ribosomal protein S6 (RPS6). RPS6 can be phosphorylated by p90 ribosomal S6 kinases (RSK) proteins. CAV1-silenced cells showed reduced levels of p-RSK1 and treatment with U0126 provoked the same effect. Despite not affecting ERK1/2 and RPS6 phosphorylation status neither MMP-9 expression nor activity, RSK1 silencing resulted in a reduced migratory and invasive capacity in vitro and reduced incidence of metastases in vivo in a novel orthotopic model. The present work provides new insights into CAV1-driven metastatic process in ES unveiling novel key nodes. PMID:27487136

  12. Caveolin-1 contributes to realgar nanoparticle therapy in human chronic myelogenous leukemia K562 cells

    PubMed Central

    Shi, Dan; Liu, Yan; Xi, Ronggang; Zou, Wei; Wu, Lijun; Zhang, Zhiran; Liu, Zhongyang; Qu, Chao; Xu, Baoli; Wang, Xiaobo

    2016-01-01

    Chronic myelogenous leukemia (CML) is characterized by the t(9;22) (q34;q11)-associated Bcr-Abl fusion gene, which is an essential element of clinical diagnosis. As a traditional Chinese medicine, realgar has been widely used for the treatment of various diseases for >1,500 years. Inspired by nano-drug, realgar nanoparticles (NPs) have been prepared with an average particle size of <100 nm in a previous work. Compared with coarse realgar, the realgar NPs have higher bioavailability. As a principal constituent protein of caveolae, caveolin-1 (Cav-1) participates in regulating various cellular physiological and pathological processes including tumorigenesis and tumor development. In previous studies, it was found that realgar NPs can inhibit several types of tumor cell proliferation. However, the therapeutic effect of realgar NPs on CML has not been fully elucidated. In the present paper, it was demonstrated that realgar NPs can inhibit the proliferation of K562 cells and degrade Bcr-Abl fusion protein effectively. Both apoptosis and autophagy were activated in a dose-dependent manner in realgar NPs treated cells, and the induction of autophagy was associated with class I phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway. Morphological analysis indicated that realgar NPs induced differentiation effectively in CML cells. Furthermore, it was identified that Cav-1 might play a crucial role in realgar NP therapy. In order to study the effects of Cav-1 on K562 cells during realgar NP treatment, a Cav-1 overexpression cell model was established by using transient transfection. The results indicated that Cav-1 overexpression inhibited K562 cell proliferation, promoted endogenic autophagy, and increased the sensitivity of K562 cells to realgar NPs. Therefore, the results demonstrated that realgar NPs degraded Bcr-Abl oncoprotein, while the underlying mechanism might be related to apoptosis and autophagy, and Cav-1 might be considered as a

  13. The significance of caveolin-1 expression in parietal epithelial cells of Bowman's capsule.

    PubMed

    Ostalska-Nowicka, D; Nowicki, M; Zachwieja, J; Kasper, M; Witt, M

    2007-11-01

    To analyse the expression of caveolin-1 in normal human kidney and during diseases leading to nephrotic syndrome in children and to compare its pattern with those observed in control samples, both human and animal. The study group was composed of 104 children diagnosed with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), lupus glomerulonephritis (LGN) and Schönlein-Henoch glomerulopathy (SH). The research protocol employed direct immunohistochemical assay with the use of mono- and polyclonal antibodies against caveolins. Kidney samples of Wistar rats, wild-type mice and caveolin-1-deficient mice were also analysed. In the control human samples, caveolin-1 was most abundant in the muscle layer of blood vessels and parietal epithelial cells (PECs). Its expression in PECs was significantly lower in children diagnosed with FSGS and LGN than in those with MCD, SH or in controls. In the control animal tissues, except for knock-out mice, caveolin-1 was present in distal convoluted tubules, PECs, endothelial cells and muscle. Caveolae are extremely stable elements of PECs and can be excluded from their cell membrane only in response to the dramatic cell reconstruction observed in FSGS and LGN.

  14. Regulation of pancreatic cancer cell migration and invasion by RhoC GTPase and Caveolin-1

    PubMed Central

    Lin, Min; DiVito, Melinda M; Merajver, Sofia D; Boyanapalli, Madanamohan; van Golen, Kenneth L

    2005-01-01

    Background In the current study we investigated the role of caveolin-1 (cav-1) in pancreatic adenocarcinoma (PC) cell migration and invasion; initial steps in metastasis. Cav-1 is the major structural protein in caveolae; small Ω-shaped invaginations within the plasma membrane. Caveolae are involved in signal transduction, wherein cav-1 acts as a scaffolding protein to organize multiple molecular complexes regulating a variety of cellular events. Recent evidence suggests a role for cav-1 in promoting cancer cell migration, invasion and metastasis; however, the molecular mechanisms have not been described. The small monomeric GTPases are among several molecules which associate with cav-1. Classically, the Rho GTPases control actin cytoskeletal reorganization during cell migration and invasion. RhoC GTPase is overexpressed in aggressive cancers that metastasize and is the predominant GTPase in PC. Like several GTPases, RhoC contains a putative cav-1 binding motif. Results Analysis of 10 PC cell lines revealed high levels of cav-1 expression in lines derived from primary tumors and low expression in those derived from metastases. Comparison of the BxPC-3 (derived from a primary tumor) and HPAF-II (derived from a metastasis) demonstrates a reciprocal relationship between cav-1 expression and p42/p44 Erk activation with PC cell migration, invasion, RhoC GTPase and p38 MAPK activation. Furthermore, inhibition of RhoC or p38 activity in HPAF-II cells leads to partial restoration of cav-1 expression. Conclusion Cav-1 expression inhibits RhoC GTPase activation and subsequent activation of the p38 MAPK pathway in primary PC cells thus restricting migration and invasion. In contrast, loss of cav-1 expression leads to RhoC-mediated migration and invasion in metastatic PC cells. PMID:15969750

  15. Caveolin-1 regulates P2X7 receptor signaling in osteoblasts.

    PubMed

    Gangadharan, Vimal; Nohe, Anja; Caplan, Jeffrey; Czymmek, Kirk; Duncan, Randall L

    2015-01-01

    The synthesis of new bone in response to a novel applied mechanical load requires a complex series of cellular signaling events in osteoblasts and osteocytes. The activation of the purinergic receptor P2X(7)R is central to this mechanotransduction signaling cascade. Recently, P2X(7)R have been found to be associated with caveolae, a subset of lipid microdomains found in several cell types. Deletion of caveolin-1 (CAV1), the primary protein constituent of caveolae in osteoblasts, results in increased bone mass, leading us to hypothesize that the P2X(7)R is scaffolded to caveolae in osteoblasts. Thus, upon activation of the P2X(7)R, we postulate that caveolae are endocytosed, thereby modulating the downstream signal. Sucrose gradient fractionation of MC3T3-E1 preosteoblasts showed that CAV1 was translocated to the denser cytosolic fractions upon stimulation with ATP. Both ATP and the more specific P2X(7)R agonist 2'(3')-O-(4-benzoylbenzoyl)ATP (BzATP) induced endocytosis of CAV1, which was inhibited when MC3T3-E1 cells were pretreated with the specific P2X7R antagonist A-839977. The P2X7R cofractionated with CAV1, but, using superresolution structured illumination microscopy, we found only a subpopulation of P2X(7)R in these lipid microdomains on the membrane of MC3T3-E1 cells. Suppression of CAV1 enhanced the intracellular Ca(2+) response to BzATP, suggesting that caveolae regulate P2X(7)R signaling. This proposed mechanism is supported by increased mineralization in CAV1 knockdown MC3T3-E1 cells treated with BzATP. These data suggest that caveolae regulate P2X(7)R signaling upon activation by undergoing endocytosis and potentially carrying with it other signaling proteins, hence controlling the spatiotemporal signaling of P2X(7)R in osteoblasts.

  16. Caveolin-1 regulates P2X7 receptor signaling in osteoblasts

    PubMed Central

    Gangadharan, Vimal; Nohe, Anja; Caplan, Jeffrey; Czymmek, Kirk

    2014-01-01

    The synthesis of new bone in response to a novel applied mechanical load requires a complex series of cellular signaling events in osteoblasts and osteocytes. The activation of the purinergic receptor P2X7R is central to this mechanotransduction signaling cascade. Recently, P2X7R have been found to be associated with caveolae, a subset of lipid microdomains found in several cell types. Deletion of caveolin-1 (CAV1), the primary protein constituent of caveolae in osteoblasts, results in increased bone mass, leading us to hypothesize that the P2X7R is scaffolded to caveolae in osteoblasts. Thus, upon activation of the P2X7R, we postulate that caveolae are endocytosed, thereby modulating the downstream signal. Sucrose gradient fractionation of MC3T3-E1 preosteoblasts showed that CAV1 was translocated to the denser cytosolic fractions upon stimulation with ATP. Both ATP and the more specific P2X7R agonist 2′(3′)-O-(4-benzoylbenzoyl)ATP (BzATP) induced endocytosis of CAV1, which was inhibited when MC3T3-E1 cells were pretreated with the specific P2X7R antagonist A-839977. The P2X7R cofractionated with CAV1, but, using superresolution structured illumination microscopy, we found only a subpopulation of P2X7R in these lipid microdomains on the membrane of MC3T3-E1 cells. Suppression of CAV1 enhanced the intracellular Ca2+ response to BzATP, suggesting that caveolae regulate P2X7R signaling. This proposed mechanism is supported by increased mineralization in CAV1 knockdown MC3T3-E1 cells treated with BzATP. These data suggest that caveolae regulate P2X7R signaling upon activation by undergoing endocytosis and potentially carrying with it other signaling proteins, hence controlling the spatiotemporal signaling of P2X7R in osteoblasts. PMID:25318104

  17. Electroacupuncture Exerts Neuroprotection through Caveolin-1 Mediated Molecular Pathway in Intracerebral Hemorrhage of Rats

    PubMed Central

    Li, Hui-Qin; Li, Yan; Chen, Zi-Xian; Zhang, Xiao-Guang; Zheng, Xia-wei; Yang, Wen-ting; Chen, Shuang

    2016-01-01

    Spontaneous intracerebral hemorrhage (ICH) is one of the most devastating types of stroke. Here, we aim to demonstrate that electroacupuncture on Baihui (GV20) exerts neuroprotection for acute ICH possibly via the caveolin-1/matrix metalloproteinase/blood-brain barrier permeability pathway. The model of ICH was established by using collagenase VII. Rats were randomly divided into three groups: Sham-operation group, Sham electroacupuncture group, and electroacupuncture group. Each group was further divided into 4 subgroups according to the time points of 6 h, 1 d, 3 d, and 7 d after ICH. The methods were used including examination of neurological deficit scores according to Longa's scale, measurement of blood-brain barrier permeability through Evans Blue content, in situ immunofluorescent detection of caveolin-1 in brains, western blot analysis of caveolin-1 in brains, and in situ zymography for measuring matrix metalloproteinase-2/9 activity in brains. Compared with Sham electroacupuncture group, electroacupuncture group has resulted in a significant improvement in neurological deficit scores and in a reduction in Evans Blue content, expression of caveolin-1, and activity of matrix metalloproteinase-2/9 at 6 h, 1 d, 3 d, and 7 d after ICH (P < 0.05). In conclusion, the present results suggested that electroacupuncture on GV20 can improve neurological deficit scores and reduce blood-brain barrier permeability after ICH, and the mechanism possibly targets caveolin-1/matrix metalloproteinase/blood-brain barrier permeability pathway. PMID:27725888

  18. Downregulation of caveolin-1 in a murine model of acute allergic airway disease.

    PubMed

    Chen, Chung-Ming; Wu, Meng-Ying; Chou, Hsiu-Chu; Lang, Yaw-Dong; Wang, Leng-Fang

    2011-02-01

    Airway remodeling refers to the structural changes in the airways of asthma. Caveolin-1 reduces cell growth and negatively regulates smooth muscle cell proliferation. The aim was to investigate lung caveolin-1 status in a murine model of acute allergic airway disease. Six- to eight-week-old female BALB/c mice were sensitized by intraperitoneal injections of phosphate-buffered saline or ovalbumin (OVA) and aluminium hydroxide on Days 0 and 14, challenged with aerosolized saline or OVA (1%) on Days 21-25, 28-32, and 35. The mice were killed 1 day after the last OVA/saline challenge. Serum OVA-specific immunoglobulin E (IgE) was measured by enzyme-linked immunosorbent assay. Peribronchial inflammation was quantified by morphometric analysis. Lung caveolin-1 and Type I collagen mRNA expression was determined by real-time reverse-transcription polymerase chain reaction. Total lung collagen was measured using Sircol Assay Kit. Serum OVA-specific IgE levels were significantly elevated in OVA-challenged mice when compared with saline-challenged mice. Percentage of inflammatory cells in the bronchoalveolar lavage was significantly higher in the OVA-challenged animals. The animals' lungs that were sensitized and challenged with OVA contained large numbers of inflammatory cells concentrated near the airways and in the perivascular areas. The thickness of the bronchial epithelial layer and smooth muscle layer and the numbers of total inflammatory cells and eosinophils significantly increased in OVA-challenged mice. Caveolin-1 mRNA expression significantly decreased and Type I collagen mRNA expression significantly increased in the lung tissue of OVA-challenged mice. These results suggest that caveolin-1 seems to be involved in the pathogenesis of airway remodeling of acute allergic airway disease. Copyright © 2011. Published by Elsevier B.V.

  19. Associated inflammation or increased flow-mediated shear stress, but not pressure alone, disrupts endothelial caveolin-1 in infants with pulmonary hypertension

    PubMed Central

    Dereddy, Narendra; Huang, Jing; Erb, Markus; Guzel, Sibel; Wolk, John H; Sett, Suvro S; Gewitz, Michael H; Mathew, Rajamma

    2012-01-01

    Endothelial caveolin-1 loss is an important feature of pulmonary hypertension (PH); the rescue of caveolin-1 abrogates experimental PH. Recent studies in human PH suggest that the endothelial caveolin-1 loss is followed by an enhanced expression of caveolin-1 in smooth muscle cells (SMC) with subsequent neointima formation. In order to evaluate caveolin-1 expression in infants with PH, we examined the available clinical histories, hemodynamic data, and the expression of caveolin-1, PECAM-1, vWF, and smooth muscle α-actin in the lung biopsy/autopsy specimens obtained from infants with congenital heart disease (CHD, n = 8) and lung disease (n = 9). In CHD group, PH associated with increased pulmonary blood flow exhibited loss of endothelial caveolin-1 and PECAM-1 in pulmonary arteries; additional vWF loss was associated with enhanced expression of caveolin-1 in SMC. In the absence of PH, increased or decreased pulmonary blood flow did not disrupt endothelial caveolin-1, PECAM-1, or vWF; nor was there any enhanced expression of caveolin-1 in SMC. In Lung Disease + PH group, caveolin-1, PECAM-1, and vWF were well preserved in seven infants, and importantly, SMC in these arteries did not exhibit enhanced caveolin-1 expression. Two infants with associated inflammatory disease exhibited loss of endothelial caveolin-1 and PECAM-1; additional loss of vWF was accompanied by enhanced expression of caveolin-1 in SMC. Thus, associated flow-induced shear stress or inflammation, but not elevated pulmonary artery pressure alone, disrupts endothelial caveolin-1. Subsequent vWF loss, indicative of extensive endothelial damage is associated with enhanced expression of caveolin-1 in SMC, which may worsen the disease. PMID:23372934

  20. Intestinal epithelial cell caveolin 1 regulates fatty acid and lipoprotein cholesterol plasma levels

    PubMed Central

    Shen, Meng-Chieh; Quinlivan, Vanessa; Anderson, Jennifer L.; Farber, Steven A.

    2017-01-01

    ABSTRACT Caveolae and their structural protein caveolin 1 (CAV1) have roles in cellular lipid processing and systemic lipid metabolism. Global deletion of CAV1 in mice results in insulin resistance and increases in atherogenic plasma lipids and cholesterol, but protects from diet-induced obesity and atherosclerosis. Despite the fundamental role of the intestinal epithelia in the regulation of dietary lipid processing and metabolism, the contributions of CAV1 to lipid metabolism in this tissue have never been directly investigated. In this study the cellular dynamics of intestinal Cav1 were visualized in zebrafish and the metabolic contributions of CAV1 were determined with mice lacking CAV1 in intestinal epithelial cells (CAV1IEC-KO). Live imaging of Cav1–GFP and fluorescently labeled caveolae cargos shows localization to the basolateral and lateral enterocyte plasma membrane (PM), suggesting Cav1 mediates transport between enterocytes and the submucosa. CAV1IEC-KO mice are protected from the elevation in circulating fasted low-density lipoprotein (LDL) cholesterol associated with a high-fat diet (HFD), but have increased postprandial LDL cholesterol, total free fatty acids (FFAs), palmitoleic acid, and palmitic acid. The increase in circulating FAs in HFD CAV1IEC-KO mice is mirrored by decreased hepatic FAs, suggesting a non-cell-autonomous role for intestinal epithelial cell CAV1 in promoting hepatic FA storage. In conclusion, CAV1 regulates circulating LDL cholesterol and several FA species via the basolateral PM of enterocytes. These results point to intestinal epithelial cell CAV1 as a potential therapeutic target to lower circulating FFAs and LDL cholesterol, as high levels are associated with development of type II diabetes and cardiovascular disease. PMID:28130355

  1. Endothelial Caveolin-1 regulates the radiation response of epithelial prostate tumors

    PubMed Central

    Klein, D; Schmitz, T; Verhelst, V; Panic, A; Schenck, M; Reis, H; Drab, M; Sak, A; Herskind, C; Maier, P; Jendrossek, V

    2015-01-01

    The membrane protein caveolin-1 (Cav1) recently emerged as a novel oncogene involved in prostate cancer progression with opposed regulation in epithelial tumor cells and the tumor stroma. Here we examined the role of stromal Cav1 for growth and radiation response of MPR31-4 prostate cancer xenograft tumors using Cav1-deficient C57Bl/6 mice. Syngeneic MPR31-4 tumors grew faster when implanted into Cav1-deficient mice. Increased tumor growth on Cav1-deficient mice was linked to decreased integration of smooth muscle cells into the wall of newly formed blood vessels and thus with a less stabilized vessel phenotype compared with tumors from Cav1 wild-type animals. However, tumor growth delay of MPR31-4 tumors grown on Cav1 knockout mice to a single high-dose irradiation with 20 Gray was more pronounced compared with tumors grown on wild-type mice. Increased radiation-induced tumor growth delay in Cav1-deficient mice was associated with an increased endothelial cell apoptosis. In vitro studies using cultured endothelial cells (ECs) confirmed that the loss of Cav1 expression increases sensitivity of ECs to radiation-induced apoptosis and reduces their clonogenic survival after irradiation. Immunohistochemical analysis of human tissue specimen further revealed that although Cav1 expression is mostly reduced in the tumor stroma of advanced and metastatic prostate cancer, the vascular compartment still expresses high levels of Cav1. In conclusion, the radiation response of MPR31-4 prostate tumors is critically regulated by Cav1 expression in the tumor vasculature. Thus, Cav1 might be a promising therapeutic target for combinatorial therapies to counteract radiation resistance of prostate cancer at the level of the tumor vasculature. PMID:25985209

  2. Ciprofloxacin mediates cancer stem cell phenotypes in lung cancer cells through caveolin-1-dependent mechanism.

    PubMed

    Phiboonchaiyanan, Preeyaporn Plaimee; Kiratipaiboon, Chayanin; Chanvorachote, Pithi

    2016-04-25

    Cancer stem cells (CSCs), a subpopulation of cancer cells with high aggressive behaviors, have been identified in many types of cancer including lung cancer as one of the key mediators driving cancer progression and metastasis. Here, we have reported for the first time that ciprofloxacin (CIP), a widely used anti-microbial drug, has a potentiating effect on CSC-like features in human non-small cell lung cancer (NSCLC) cells. CIP treatment promoted CSC-like phenotypes, including enhanced anchorage-independent growth and spheroid formation. The known lung CSC markers: CD133, CD44, ABCG2 and ALDH1A1 were found to be significantly increased, while the factors involving in epithelial to mesenchymal transition (EMT): Slug and Snail, were depleted. Also, self-renewal transcription factors Oct-4 and Nanog were found to be up-regulated in CIP-treated cells. The treatment of CIP on CSC-rich populations obtained from secondary spheroids resulted in the further increase of CSC markers. In addition, we have proven that the mechanistic insight of the CIP induced stemness is through Caveolin-1 (Cav-1)-dependent mechanism. The specific suppression of Cav-1 by stably transfected Cav-1 shRNA plasmid dramatically reduced the effect of CIP on CSC markers as well as the CIP-induced spheroid formation ability. Cav-1 was shown to activate protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) pathways in CSC-rich population; however, such an effect was rarely found in the main lung cancer cells population. These findings reveal a novel effect of CIP in positively regulating CSCs in lung cancer cells via the activation of Cav-1, Akt and ERK, and may provoke the awareness of appropriate therapeutic strategy in cancer patients.

  3. The Potential Protective Role of Caveolin-1 in Intestinal Inflammation in TNBS-Induced Murine Colitis

    PubMed Central

    Ma, Yanbing; Qing, Gefei; Bernstein, Charles N.; Warrington, Richard J.; Peng, Zhikang

    2015-01-01

    Background Caveolin-1 (Cav-1) is a multifunctional scaffolding protein serving as a platform for the cell’s signal-transduction and playing an important role in inflammation. However, its role in inflammatory bowel disease is not clear. A recent study showed that Cav-1 is increased and mediates angiogenesis in dextran sodium sulphate-induced colitis, which are contradictory to our pilot findings in 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis. In the present study, we further clarified the role of Cav-1 in TNBS-induced colitis. Methods In BALB/c mice, acute colitis was induced by intra-rectal administration of one dose TNBS, while chronic colitis was induced by administration of TNBS once a week for 7 weeks. To assess the effects of complete loss of Cav-1, Cav-1 knockout (Cav-1−/−) and control wild-type C57 mice received one TNBS administration. Body weight and clinical scores were monitored. Colon Cav-1 and pro-inflammatory cytokine levels were quantified through ELISAs. Inflammation was evaluated through histological analysis. Results Colon Cav-1 levels were significantly decreased in TNBS-induced colitis mice when compared to normal mice and also inversely correlated with colon inflammation scores and proinflammatory cytokine levels (IL-17, IFN-γ and TNF) significantly. Furthermore, after administration of TNBS, Cav-1−/− mice showed significantly increased clinical and colon inflammatory scores and body weight loss when compared with control mice. Conclusions and Significance Cav-1 may play a protective role in the development of TNBS-induced colitis. Our findings raise an important issue in the evaluation of specific molecules in animal models that different models may exhibit opposite results because of the different mechanisms involved. PMID:25756273

  4. Impairment of Transforming Growth Factor β Signaling in Caveolin-1-deficient Hepatocytes

    PubMed Central

    Mayoral, Rafael; Valverde, Ángela M.; Llorente Izquierdo, Cristina; González-Rodríguez, Águeda; Boscá, Lisardo; Martín-Sanz, Paloma

    2010-01-01

    Caveolin-1 (Cav-1) is the main structural protein of caveolae and plays an important role in various cellular processes such as vesicular transport, cholesterol homeostasis, and signal transduction pathways. The expression and functional role of Cav-1 have been reported in liver and in hepatocyte cell lines, in human cirrhotic liver, and in hepatocellular carcinomas. Previous studies demonstrated that Cav-1 was dispensable for liver regeneration, because Cav-1−/− animals survived and fully regenerated liver function and size after partial hepatectomy. In this study, we have investigated the mechanisms by which the lack of Cav-1 accelerates liver regeneration after partial hepatectomy. The data show that transforming growth factor β (TGF-β) signaling is impaired in regenerating liver of Cav-1−/− mice and in hepatocytes derived from these animals. TGF-β receptors I and II do not colocalize in the same membrane fraction in the hepatocytes derived from Cav-1−/− mice, as Smad2/3 signaling decreased in the absence of Cav-1 at the time that the transcriptional corepressor SnoN accumulates. Accordingly, the expression of TGF-β target genes, such as plasminogen activator inhibitor-1, is decreased due to the presence of the high levels of SnoN. Moreover, hepatocyte growth factor inhibited TGF-β signaling in the absence of Cav-1 by increasing SnoN expression. Taken together, these data might help to unravel why Cav-1-deficient mice exhibit an accelerated liver regeneration after partial hepatectomy and add new insights on the molecular mechanisms controlling the initial commitment to hepatocyte proliferation. PMID:19966340

  5. Identification, expression pattern, cellular location and potential role of the caveolin-1 gene from Artemia sinica.

    PubMed

    Li, Xuejie; Yao, Feng; Zhang, Wei; Cheng, Cheng; Chu, Bing; Liu, Yan; Mei, Yanli; Wu, Yang; Zou, Xiangyang; Hou, Lin

    2014-05-01

    Caveolins are integral membrane proteins that serve as scaffolds to recruit numerous signaling molecules. Caveolins play an important role in membrane trafficking, signal transduction, substrate transport and endocytosis in differentiated cells. In this study, a caveolin-1 gene from Artemia sinica (As-cav-1) was successfully cloned for the first time. The full-length cDNA of As-cav-1 comprises 974 bp, with a 675 bp open reading frame (ORF) that encodes a polypeptide of 224 amino acids with a caveolin scaffolding domain (CSD) and two transmembrane domains. Multiple sequence alignment revealed that the putative As-CAV-1 protein sequence was relatively conserved across species, especially in the CSD domain. Real-time PCR revealed high levels of the As-cav-1 transcript at 0h of embryo development. Furthermore, As-cav-1 transcripts were highly upregulated under high salinity (200‰) and low temperature stresses (15°C). To further characterize As-cav-1, recombinant pET30a-cav-1 protein was expressed using a prokaryotic expression system. The recombinant protein comprised 290 amino acids with a theoretical molecular weight of 32kDa, and a predicted isoelectric point of 5.6. Western blotting of the expression levels of As-CAV-1 during different embryo development stages revealed that As-CAV-1 levels decreased gradually during development stages from 0 h to 40 h, and increased at 3d. Furthermore, western blotting showed that As-CAV-1 was upregulated to its highest expression level by low temperature stress (15°C) and high salinity. Confocal laser microscopy analysis, using antibodies generated against the recombinant As-CAV-1 protein, showed that As-CAV-1 was mostly located in the cell membrane. Our results suggested that As-cav-1 plays a vital role in protecting embryos from high salt damage and low temperature stress, especially during post-diapause embryonic development. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Identification of a maize chlorotic dwarf virus silencing suppressor protein

    USDA-ARS?s Scientific Manuscript database

    Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389 kDa proteolytically processed polyprotein. We show that an N-terminal 78kDa polyprotein (R78) has silencing suppressor activity, that it is cleaved by the viral...

  7. The Importance of Caveolin-1 as Key-Regulator of Three-Dimensional Growth in Thyroid Cancer Cells Cultured under Real and Simulated Microgravity Conditions.

    PubMed

    Riwaldt, Stefan; Bauer, Johann; Pietsch, Jessica; Braun, Markus; Segerer, Jürgen; Schwarzwälder, Achim; Corydon, Thomas J; Infanger, Manfred; Grimm, Daniela

    2015-11-30

    We recently demonstrated that the CAV1 gene was down-regulated, when poorly differentiated thyroid FTC-133 cancer cells formed spheroids under simulated microgravity conditions. Here, we present evidence that the caveolin-1 protein is involved in the inhibition of spheroid formation, when confluent monolayers are exposed to microgravity. The evidence is based on proteins detected in cells and their supernatants of the recent spaceflight experiment: "NanoRacks-CellBox-Thyroid Cancer". The culture supernatant had been collected in a special container adjacent to the flight hardware incubation chamber and stored at low temperature until it was analyzed by Multi-Analyte Profiling (MAP) technology, while the cells remaining in the incubation chamber were fixed by RNAlater and examined by mass spectrometry. The soluble proteins identified by MAP were investigated in regard to their mutual interactions and their influence on proteins, which were associated with the cells secreting the soluble proteins and had been identified in a preceding study. A Pathway Studio v.11 analysis of the soluble and cell-associated proteins together with protein kinase C alpha (PRKCA) suggests that caveolin-1 is involved, when plasminogen enriched in the extracellular space is not activated and the vascular cellular adhesion molecule (VCAM-1) mediated cell-cell adhesion is simultaneously strengthened and activated PRKCA is recruited in caveolae, while the thyroid cancer cells do not form spheroids.

  8. The Importance of Caveolin-1 as Key-Regulator of Three-Dimensional Growth in Thyroid Cancer Cells Cultured under Real and Simulated Microgravity Conditions

    PubMed Central

    Riwaldt, Stefan; Bauer, Johann; Pietsch, Jessica; Braun, Markus; Segerer, Jürgen; Schwarzwälder, Achim; Corydon, Thomas J.; Infanger, Manfred; Grimm, Daniela

    2015-01-01

    We recently demonstrated that the CAV1 gene was down-regulated, when poorly differentiated thyroid FTC-133 cancer cells formed spheroids under simulated microgravity conditions. Here, we present evidence that the caveolin-1 protein is involved in the inhibition of spheroid formation, when confluent monolayers are exposed to microgravity. The evidence is based on proteins detected in cells and their supernatants of the recent spaceflight experiment: “NanoRacks-CellBox-Thyroid Cancer”. The culture supernatant had been collected in a special container adjacent to the flight hardware incubation chamber and stored at low temperature until it was analyzed by Multi-Analyte Profiling (MAP) technology, while the cells remaining in the incubation chamber were fixed by RNAlater and examined by mass spectrometry. The soluble proteins identified by MAP were investigated in regard to their mutual interactions and their influence on proteins, which were associated with the cells secreting the soluble proteins and had been identified in a preceding study. A Pathway Studio v.11 analysis of the soluble and cell-associated proteins together with protein kinase C alpha (PRKCA) suggests that caveolin-1 is involved, when plasminogen enriched in the extracellular space is not activated and the vascular cellular adhesion molecule (VCAM-1) mediated cell–cell adhesion is simultaneously strengthened and activated PRKCA is recruited in caveolae, while the thyroid cancer cells do not form spheroids. PMID:26633361

  9. Caveolin-1-Enhanced Motility and Focal Adhesion Turnover Require Tyrosine-14 but Not Accumulation to the Rear in Metastatic Cancer Cells

    PubMed Central

    Ortiz, Rina J.; Lobos, Lorena; Díaz, María I.; Díaz, Natalia; Härtel, Steffen; Leyton, Lisette; Quest, Andrew F. G.

    2012-01-01

    Caveolin-1 is known to promote cell migration, and increased caveolin-1 expression is associated with tumor progression and metastasis. In fibroblasts, caveolin-1 polarization and phosphorylation of tyrosine-14 are essential to promote migration. However, the role of caveolin-1 in migration of metastatic cells remains poorly defined. Here, caveolin-1 participation in metastatic cell migration was evaluated by shRNA targeting of endogenous caveolin-1 in MDA-MB-231 human breast cancer cells and ectopic expression in B16-F10 mouse melanoma cells. Depletion of caveolin-1 in MDA-MB-231 cells reduced, while expression in B16-F10 cells promoted migration, polarization and focal adhesion turnover in a sequence of events that involved phosphorylation of tyrosine-14 and Rac-1 activation. In B16-F10 cells, expression of a non-phosphorylatable tyrosine-14 to phenylalanine mutant failed to recapitulate the effects observed with wild-type caveolin-1. Alternatively, treatment of MDA-MB-231 cells with the Src family kinase inhibitor PP2 reduced caveolin-1 phosphorylation on tyrosine-14 and cell migration. Surprisingly, unlike for fibroblasts, caveolin-1 polarization and re-localization to the trailing edge were not observed in migrating metastatic cells. Thus, expression and phosphorylation, but not polarization of caveolin-1 favor the highly mobile phenotype of metastatic cells. PMID:22505999

  10. Modified Panax ginseng Extract Inhibits uPAR-Mediated α[Formula: see text]β1-Integrin Signaling by Modulating Caveolin-1 to Induce Early Apoptosis in Lung Cancer Cells.

    PubMed

    Hwang, In-Hu; Kwon, Yong-Kyun; Cho, Chong-Kwan; Lee, Yeon-Weol; Sung, Jung-Suk; Joo, Jong-Cheon; Lee, Kyung-Bok; Yoo, Hwa-Seung; Jang, Ik-Soon

    2016-01-01

    Urokinase receptor (uPAR) is enhanced in many human cancer cells and is frequently an indicator of poor prognosis. Activation of [Formula: see text]1-integrin requires caveolin-1 and is regulated by uPAR. However, the underlying molecular mechanism responsible for the interaction between uPAR and [Formula: see text]1-integrin remains obscure. We found that modified regular Panax ginseng extract (MRGX) had a negative modulating effect on the uPAR/[Formula: see text]1-integrin interaction, disrupted the uPAR/integrin interaction by modulating caveoline-1, and caused early apoptosis in cancer cells. Additionally, we found that siRNA-mediated caveoline-1 downregulation inhibited uPAR-mediated [Formula: see text]1-integrin signaling, whereas caveoline-1 up-regulation stimulated the signaling, which suppressed p53 expression, thereby indicating negative crosstalk exists between the integrin [Formula: see text]1 and the p53 pathways. Thus, these findings identify a novel mechanism whereby the inhibition of [Formula: see text]1 integrin and the activation of p53 modulate the expression of the anti-apoptotic proteins that are crucially involved in inducing apoptosis in A549 lung cancer cells. Furthermore, MRGX causes changes in the expressions of members of the Bcl-2 family (Bax and Bcl-2) in a pro-apoptotic manner. In addition, MGRX-mediated inhibition of [Formula: see text]1 integrin attenuates ERK phosphorylation (p-ERK), which up-regulates caspase-8 and Bax. Therefore, ERK may affect mitochondria through a negative regulation of caspase-8 and Bax. Taken together, these findings reveal that MRGX is involved in uPAR-[Formula: see text]1-integrin signaling by modulating caveolin-1 signaling to induce early apoptosis in A549 lung-cancer cells and strongly indicate that MRGX might be useful as a herbal medicine and may lead to the development of new herbal medicine that would suppress the growth of lung-cancer cells.

  11. Inhibition of macrophage-derived foam cell formation by ezetimibe via the caveolin-1/MAPK pathway.

    PubMed

    Qin, Li; Yang, Yun-Bo; Yang, Yi-Xin; Zhu, Neng; Liu, Zheng; Ni, Ya-Guang; Li, Shun-Xiang; Zheng, Xi-Long; Liao, Duan-Fang

    2016-02-01

    Ezetimibe, a selective inhibitor of intestinal cholesterol absorption, effectively reduces plasma cholesterol, but its effect on atherosclerosis is unclear. Foam cell formation has been implicated as a key mediator during the development of atherosclerosis. The purpose of this study was to investigate the effects of ezetimibe on foam cell formation and explore the underlying mechanism. The results presented here show that ezetimibe reduces atherosclerotic lesions in apolipoprotein E deficient (apoE-/-) mice by lowering cholesterol levels. Treatment of macrophages with Chol:MβCD resulted in foam cell formation, which was concentration-dependently inhibited by the presence of ezetimibe. Mechanically, ezetimibe treatment downregulated the expression of CD36 and scavenger receptor class B1 (SR-B1), but upregulated the expression of apoE and caveolin-1 in macrophage-derived foam cells, which kept consistent with our microarray results. Moreover, treatment with ezetimibe abrogated the increase of phospho-extracellular signal regulated kinase (ERK) 1/2 and their nuclear accumulation in foam cells. Inhibition of the MAPK pathway by the MEK inhibitor PD98059 attenuated the inhibitory effect of ezetimibe on the expression of p-ERK1/2 and caveolin-1. Taken together, these results showed that ezetimibe suppressed foam cell formation via the caveolin-1/MAPK signalling pathway, suggesting that inhibition of foam cell formation might be a novel mechanism underlying the anti-atherosclerotic effect of ezetimibe.

  12. Androgen Receptor Localizes to Plasma Membrane by Binding to Caveolin-1 in Mouse Sertoli Cells

    PubMed Central

    Deng, Qiong; Wu, Yong; Zhang, Zeng; Wang, Yue; Li, Minghua

    2017-01-01

    The nonclassical androgen signaling pathway translates signals into alterations in cellular function within minutes, and this action is proposed to be mediated by an androgen receptor (AR) localized to the plasma membrane. This study was designed to determine the mechanism underlying the membrane association of androgen receptor in TM4 cells, a mouse Sertoli cell line. Western blot analysis indicated testosterone-induced AR translocation to the cell membrane. Data from coimmunoprecipitation indicated that AR is associated with caveolin-1, and testosterone enhanced this association. Knockdown of caveolin-1 by shRNA decreased the amount of AR localized to membrane fraction and prevented AR membrane trafficking after being exposed to testosterone at physiological concentration. The palmitoylation inhibitor 2-bromopalmitate decreased AR membrane localization in basal condition and completely blocked testosterone-induced AR translocation to membrane fraction. These data suggested that AR localized to membrane fraction by binding with caveolin-1 through palmitoylation of the cysteine residue. This study provided a new evidence for AR membrane localization and its application for clarifying the nonclassical signaling pathway of androgens. PMID:28642789

  13. Androgen Receptor Localizes to Plasma Membrane by Binding to Caveolin-1 in Mouse Sertoli Cells.

    PubMed

    Deng, Qiong; Wu, Yong; Zhang, Zeng; Wang, Yue; Li, Minghua; Liang, Hui; Gui, Yaoting

    2017-01-01

    The nonclassical androgen signaling pathway translates signals into alterations in cellular function within minutes, and this action is proposed to be mediated by an androgen receptor (AR) localized to the plasma membrane. This study was designed to determine the mechanism underlying the membrane association of androgen receptor in TM4 cells, a mouse Sertoli cell line. Western blot analysis indicated testosterone-induced AR translocation to the cell membrane. Data from coimmunoprecipitation indicated that AR is associated with caveolin-1, and testosterone enhanced this association. Knockdown of caveolin-1 by shRNA decreased the amount of AR localized to membrane fraction and prevented AR membrane trafficking after being exposed to testosterone at physiological concentration. The palmitoylation inhibitor 2-bromopalmitate decreased AR membrane localization in basal condition and completely blocked testosterone-induced AR translocation to membrane fraction. These data suggested that AR localized to membrane fraction by binding with caveolin-1 through palmitoylation of the cysteine residue. This study provided a new evidence for AR membrane localization and its application for clarifying the nonclassical signaling pathway of androgens.

  14. Interphase adhesion geometry is transmitted to an internal regulator for spindle orientation via caveolin-1

    PubMed Central

    Matsumura, Shigeru; Kojidani, Tomoko; Kamioka, Yuji; Uchida, Seiichi; Haraguchi, Tokuko; Kimura, Akatsuki; Toyoshima, Fumiko

    2016-01-01

    Despite theoretical and physical studies implying that cell-extracellular matrix adhesion geometry governs the orientation of the cell division axis, the molecular mechanisms that translate interphase adhesion geometry to the mitotic spindle orientation remain elusive. Here, we show that the cellular edge retraction during mitotic cell rounding correlates with the spindle axis. At the onset of mitotic cell rounding, caveolin-1 is targeted to the retracting cortical region at the proximal end of retraction fibres, where ganglioside GM1-enriched membrane domains with clusters of caveola-like structures are formed in an integrin and RhoA-dependent manner. Furthermore, Gαi1–LGN–NuMA, a well-known regulatory complex of spindle orientation, is targeted to the caveolin-1-enriched cortical region to guide the spindle axis towards the cellular edge retraction. We propose that retraction-induced cortical heterogeneity of caveolin-1 during mitotic cell rounding sets the spindle orientation in the context of adhesion geometry. PMID:27292265

  15. High-mobility group box protein 1 promotes the survival of myeloid-derived suppressor cells by inducing autophagy.

    PubMed

    Parker, Katherine H; Horn, Lucas A; Ostrand-Rosenberg, Suzanne

    2016-09-01

    Myeloid-derived suppressor cells are immune-suppressive cells that are elevated in most individuals with cancer, where their accumulation and suppressive activity are driven by inflammation. As myeloid-derived suppressor cells inhibit anti-tumor immunity and promote tumor progression, we are determining how their viability is regulated. Previous studies have established that the damage-associated molecular pattern molecule high-mobility group box protein 1 drives myeloid-derived suppressor cell accumulation and suppressive potency and is ubiquitously present in the tumor microenvironment. As high-mobility group box protein 1 also facilitates tumor cell survival by inducing autophagy, we sought to determine if high-mobility group box protein 1 regulates myeloid-derived suppressor cell survival through induction of autophagy. Inhibition of autophagy increased the quantity of apoptotic myeloid-derived suppressor cells, demonstrating that autophagy extends the survival and increases the viability of myeloid-derived suppressor cells. Inhibition of high-mobility group box protein 1 similarly increased the level of apoptotic myeloid-derived suppressor cells and reduced myeloid-derived suppressor cell autophagy, demonstrating that in addition to inducing the accumulation of myeloid-derived suppressor cells, high-mobility group box protein 1 sustains myeloid-derived suppressor cell viability. Circulating myeloid-derived suppressor cells have a default autophagic phenotype, and tumor-infiltrating myeloid-derived suppressor cells are more autophagic, consistent with the concept that inflammatory and hypoxic conditions within the microenvironment of solid tumors contribute to tumor progression by enhancing immune-suppressive myeloid-derived suppressor cells. Overall, these results demonstrate that in addition to previously recognized protumor effects, high-mobility group box protein 1 contributes to tumor progression by increasing myeloid-derived suppressor cell viability by

  16. Caveolin-1 mediates inflammatory breast cancer cell invasion via the Akt1 pathway and RhoC GTPase.

    PubMed

    Joglekar, Madhura; Elbazanti, Weam O; Weitzman, Matthew D; Lehman, Heather L; van Golen, Kenneth L

    2015-06-01

    With a propensity to invade the dermal lymphatic vessels of the skin overlying the breast and readily metastasize, inflammatory breast cancer (IBC) is arguably the deadliest form of breast cancer. We previously reported that caveolin-1 is overexpressed in IBC and that RhoC GTPase is a metastatic switch responsible for the invasive phenotype. RhoC-driven invasion requires phosphorylation by Akt1. Using a reliable IBC cell line we set out to determine if caveolin-1 expression affects RhoC-mediated IBC invasion. Caveolin-1 was down regulated by introduction of siRNA or a caveolin scaffolding domain. The ability of the cells to invade was tested and the status of Akt1 and RhoC GTPase examined. IBC cell invasion is significantly decreased when caveolin-1 is down regulated. Activation of Akt1 is decreased when caveolin-1 is down regulated, leading to decreased phosphorylation of RhoC GTPase. Thus, we report here that caveolin-1 overexpression mediates IBC cell invasion through activation Akt1, which phosphorylates RhoC GTPase.

  17. CAVEOLIN-1 expression in brain metastasis from lung cancer predicts worse outcome and radioresistance, irrespective of tumor histotype.

    PubMed

    Duregon, Eleonora; Senetta, Rebecca; Pittaro, Alessandra; Verdun di Cantogno, Ludovica; Stella, Giulia; De Blasi, Pierpaolo; Zorzetto, Michele; Mantovani, Cristina; Papotti, Mauro; Cassoni, Paola

    2015-10-06

    Brain metastases develop in one-third of patients with non-small-cell lung cancer and are associated with a dismal prognosis, irrespective of surgery or chemo-radiotherapy. Pathological markers for predicting outcomes after surgical resection and radiotherapy responsiveness are still lacking. Caveolin 1 has been associated with chemo- and radioresistance in various tumors, including non-small-cell lung cancer. Here, caveolin 1 expression was assessed in a series of 69 brain metastases from non-small-cell lung cancer and matched primary tumors to determine its role in predicting survival and radiotherapy responsiveness. Only caveolin 1 expression in brain metastasis was associated with poor prognosis and an increased risk of death (log rank test, p = 0.015). Moreover, in the younger patients (median age of <54 years), caveolin 1 expression neutralized the favorable effect of young age on survival compared with the older patients. Among the radiotherapy-treated patients, an increased risk of death was detected in the group with caveolin 1-positive brain metastasis (14 out of 22 patients, HR=6.839, 95% CI 1.849 to 25.301, Wald test p = 0.004). Overall, caveolin 1 expression in brain metastasis from non-small-cell lung cancer is independently predictive of worse outcome and radioresistance and could become an additional tool for personalized therapy in the critical subset of brain-metastatic non-small-cell lung cancer patients.

  18. Caveolin-1-deficient mice show defects in innate immunity and inflammatory immune response during Salmonella enterica serovar Typhimurium infection.

    PubMed

    Medina, Freddy A; de Almeida, Cecilia J; Dew, Elliott; Li, Jiangwei; Bonuccelli, Gloria; Williams, Terence M; Cohen, Alex W; Pestell, Richard G; Frank, Philippe G; Tanowitz, Herbert B; Lisanti, Michael P

    2006-12-01

    A number of studies have shown an association of pathogens with caveolae. To this date, however, there are no studies showing a role for caveolin-1 in modulating immune responses against pathogens. Interestingly, expression of caveolin-1 has been shown to occur in a regulated manner in immune cells in response to lipopolysaccharide (LPS). Here, we sought to determine the role of caveolin-1 (Cav-1) expression in Salmonella pathogenesis. Cav-1(-/-) mice displayed a significant decrease in survival when challenged with Salmonella enterica serovar Typhimurium. Spleen and tissue burdens were significantly higher in Cav-1(-/-) mice. However, infection of Cav-1(-/-) macrophages with serovar Typhimurium did not result in differences in bacterial invasion. In addition, Cav-1(-/-) mice displayed increased production of inflammatory cytokines, chemokines, and nitric oxide. Regardless of this, Cav-1(-/-) mice were unable to control the systemic infection of Salmonella. The increased chemokine production in Cav-1(-/-) mice resulted in greater infiltration of neutrophils into granulomas but did not alter the number of granulomas present. This was accompanied by increased necrosis in the liver. However, Cav-1(-/-) macrophages displayed increased inflammatory responses and increased nitric oxide production in vitro in response to Salmonella LPS. These results show that caveolin-1 plays a key role in regulating anti-inflammatory responses in macrophages. Taken together, these data suggest that the increased production of toxic mediators from macrophages lacking caveolin-1 is likely to be responsible for the marked susceptibility of caveolin-1-deficient mice to S. enterica serovar Typhimurium.

  19. Dissociation of Hyperglycemia from Altered Vascular Contraction and Relaxation Mechanisms in Caveolin-1 Null Mice

    PubMed Central

    Pojoga, Luminita H.; Yao, Tham M.; Opsasnick, Lauren A.; Garza, Amanda E.; Reslan, Ossama M.; Adler, Gail K.; Williams, Gordon H.

    2014-01-01

    Hyperglycemia and endothelial dysfunction are associated with hypertension, but the specific causality and genetic underpinning are unclear. Caveolin-1 (cav-1) is a plasmalemmal anchoring protein and modulator of vascular function and glucose homeostasis. Cav-1 gene variants are associated with reduced insulin sensitivity in hypertensive individuals, and cav-1−/− mice show endothelial dysfunction, hyperglycemia, and increased blood pressure (BP). On the other hand, insulin-sensitizing therapy with metformin may inadequately control hyperglycemia while affecting the vascular outcome in certain patients with diabetes. To test whether the pressor and vascular changes in cav-1 deficiency states are related to hyperglycemia and to assess the vascular mechanisms of metformin under these conditions, wild-type (WT) and cav-1−/− mice were treated with either placebo or metformin (400 mg/kg daily for 21 days). BP and fasting blood glucose were in cav-1−/− > WT and did not change with metformin. Phenylephrine (Phe)- and KCl-induced aortic contraction was in cav-1−/− < WT; endothelium removal, the nitric-oxide synthase (NOS) blocker l-NAME (Nω-nitro-l-arginine methyl ester), or soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) enhanced Phe contraction, and metformin blunted this effect. Acetylcholine-induced relaxation was in cav-1−/− > WT, abolished by endothelium removal, l-NAME or ODQ, and reduced with metformin. Nitric oxide donor sodium nitroprusside was more potent in inducing relaxation in cav-1−/− than in WT, and metformin reversed this effect. Aortic eNOS, AMPK, and sGC were in cav-1−/− > WT, and metformin decreased total and phosphorylated eNOS and AMPK in cav-1−/−. Thus, metformin inhibits both vascular contraction and NO-cGMP-dependent relaxation but does not affect BP or blood glucose in cav-1−/− mice, suggesting dissociation of hyperglycemia from altered vascular function in cav-1

  20. Inhibition of renal caveolin-1 reduces natriuresis and produces hypertension in sodium-loaded rats

    PubMed Central

    Gildea, John J.; Kemp, Brandon A.; Howell, Nancy L.; Van Sciver, Robert E.; Carey, Robert M.

    2011-01-01

    Renal dopamine receptor function and ion transport inhibition are impaired in essential hypertension. We recently reported that caveolin-1 (CAV1) and lipid rafts are necessary for normal D1-like receptor-dependent internalization of Na-K-ATPase in human proximal tubule cells. We now hypothesize that CAV1 is necessary for the regulation of urine sodium (Na+) excretion (UNaV) and mean arterial blood pressure (MAP) in vivo. Acute renal interstitial (RI) infusion into Sprague-Dawley rats of 1 μg·kg−1·min−1 fenoldopam (FEN; D1-like receptor agonist) caused a 0.46 ± 0.15-μmol/min increase in UNaV (over baseline of 0.29 ± 0.04 μmol/min; P < 0.01). This increase was seen in Na+-loaded rats, but not in those under a normal-sodium load. Coinfusion with β-methyl cyclodextrin (βMCD; lipid raft disrupter, 200 μg·kg−1·min−1) completely blocked this FEN-induced natriuresis (P < 0.001). Long-term (3 day) lipid raft disruption via continuous RI infusion of 80 μg·kg−1·min−1 βMCD decreased renal cortical CAV1 expression (47.3 ± 6.4%; P < 0.01) and increased MAP (32.4 ± 6.6 mmHg; P < 0.001) compared with vehicle-infused animals. To determine whether the MAP rise was due to a CAV1-dependent lipid raft-mediated disruption, Na+-loaded rats were given a bolus RI infusion of CAV1 siRNA. Two days postinfusion, cortical CAV1 expression was decreased by 73.6 ± 8.2% (P < 0.001) and the animals showed an increase in MAP by 17.4 ± 2.9 mmHg (P < 0.01) compared with animals receiving scrambled control siRNA. In summary, acute kidney-specific lipid raft disruption decreases CAV1 expression and blocks D1-like receptor-induced natriuresis. Furthermore, chronic disruption of lipid rafts or CAV1 protein expression in the kidney induces hypertension. PMID:21289050

  1. Inhibition of renal caveolin-1 reduces natriuresis and produces hypertension in sodium-loaded rats.

    PubMed

    Gildea, John J; Kemp, Brandon A; Howell, Nancy L; Van Sciver, Robert E; Carey, Robert M; Felder, Robin A

    2011-04-01

    Renal dopamine receptor function and ion transport inhibition are impaired in essential hypertension. We recently reported that caveolin-1 (CAV1) and lipid rafts are necessary for normal D(1)-like receptor-dependent internalization of Na-K-ATPase in human proximal tubule cells. We now hypothesize that CAV1 is necessary for the regulation of urine sodium (Na(+)) excretion (U(Na)V) and mean arterial blood pressure (MAP) in vivo. Acute renal interstitial (RI) infusion into Sprague-Dawley rats of 1 μg·kg⁻¹·min⁻¹ fenoldopam (FEN; D(1)-like receptor agonist) caused a 0.46 ± 0.15-μmol/min increase in U(Na)V (over baseline of 0.29 ± 0.04 μmol/min; P < 0.01). This increase was seen in Na(+)-loaded rats, but not in those under a normal-sodium load. Coinfusion with β-methyl cyclodextrin (βMCD; lipid raft disrupter, 200 μg·kg⁻¹·min⁻¹) completely blocked this FEN-induced natriuresis (P < 0.001). Long-term (3 day) lipid raft disruption via continuous RI infusion of 80 μg·kg⁻¹·min⁻¹ βMCD decreased renal cortical CAV1 expression (47.3 ± 6.4%; P < 0.01) and increased MAP (32.4 ± 6.6 mmHg; P < 0.001) compared with vehicle-infused animals. To determine whether the MAP rise was due to a CAV1-dependent lipid raft-mediated disruption, Na(+)-loaded rats were given a bolus RI infusion of CAV1 siRNA. Two days postinfusion, cortical CAV1 expression was decreased by 73.6 ± 8.2% (P < 0.001) and the animals showed an increase in MAP by 17.4 ± 2.9 mmHg (P < 0.01) compared with animals receiving scrambled control siRNA. In summary, acute kidney-specific lipid raft disruption decreases CAV1 expression and blocks D(1)-like receptor-induced natriuresis. Furthermore, chronic disruption of lipid rafts or CAV1 protein expression in the kidney induces hypertension.

  2. Caveolin-1 down-regulates inducible nitric oxide synthase via the proteasome pathway in human colon carcinoma cells

    PubMed Central

    Felley-Bosco, Emanuela; Bender, Florent C.; Courjault-Gautier, Françoise; Bron, Claude; Quest, Andrew F. G.

    2000-01-01

    To investigate whether caveolin-1 (cav-1) may modulate inducible nitric oxide synthase (iNOS) function in intact cells, the human intestinal carcinoma cell lines HT29 and DLD1 that have low endogenous cav-1 levels were transfected with cav-1 cDNA. In nontransfected cells, iNOS mRNA and protein levels were increased by the addition of a mix of cytokines. Ectopic expression of cav-1 in both cell lines correlated with significantly decreased iNOS activity and protein levels. This effect was linked to a posttranscriptional mechanism involving enhanced iNOS protein degradation by the proteasome pathway, because (i) induction of iNOS mRNA by cytokines was not affected and (ii) iNOS protein levels increased in the presence of the proteasome inhibitors N-acetyl-Leu-Leu-Norleucinal and lactacystin. In addition, a small amount of iNOS was found to cofractionate with cav-1 in Triton X-100-insoluble membrane fractions where also iNOS degradation was apparent. As has been described for endothelial and neuronal NOS isoenzymes, direct binding between cav-1 and human iNOS was detected in vitro. Taken together, these results suggest that cav-1 promotes iNOS presence in detergent-insoluble membrane fractions and degradation there via the proteasome pathway. PMID:11114180

  3. Caveolin-1 down-regulates inducible nitric oxide synthase via the proteasome pathway in human colon carcinoma cells.

    PubMed

    Felley-Bosco, E; Bender, F C; Courjault-Gautier, F; Bron, C; Quest, A F

    2000-12-19

    To investigate whether caveolin-1 (cav-1) may modulate inducible nitric oxide synthase (iNOS) function in intact cells, the human intestinal carcinoma cell lines HT29 and DLD1 that have low endogenous cav-1 levels were transfected with cav-1 cDNA. In nontransfected cells, iNOS mRNA and protein levels were increased by the addition of a mix of cytokines. Ectopic expression of cav-1 in both cell lines correlated with significantly decreased iNOS activity and protein levels. This effect was linked to a posttranscriptional mechanism involving enhanced iNOS protein degradation by the proteasome pathway, because (i) induction of iNOS mRNA by cytokines was not affected and (ii) iNOS protein levels increased in the presence of the proteasome inhibitors N-acetyl-Leu-Leu-Norleucinal and lactacystin. In addition, a small amount of iNOS was found to cofractionate with cav-1 in Triton X-100-insoluble membrane fractions where also iNOS degradation was apparent. As has been described for endothelial and neuronal NOS isoenzymes, direct binding between cav-1 and human iNOS was detected in vitro. Taken together, these results suggest that cav-1 promotes iNOS presence in detergent-insoluble membrane fractions and degradation there via the proteasome pathway.

  4. Identification of a third protein 4.1 tumor suppressor, protein 4.1R, in meningioma pathogenesis

    SciTech Connect

    Robb, Victoria A.; Li, Wen; Gascard, Philippe; Perry, Arie; Mohandas, Narla; Gutmann, David H.

    2003-06-11

    Meningiomas are common tumors of the central nervous system, however, the mechanisms under lying their pathogenesis are largely undefined. Two members of the Protein 4.1 super family, the neuro fibromatosis 2 (NF2) gene product (merlin/schwannomin) and Protein 4.1B have been implicated as meningioma tumor suppressors. In this report, we demonstrate that another Protein 4.1 family member, Protein 4.1R, also functions as a meningioma tumor suppressor. Based on the assignment of the Protein 4.1R gene to chromosome 1p32-36, a common region of deletion observed in meningiomas, we analyzed Protein 4.1R expression in meningioma cell lines and surgical tumor specimens. We observed loss of Protein 4.1R protein expression in two meningioma cell lines (IOMM-Lee, CH157-MN) by Western blotting as well as in 6 of 15 sporadic meningioma as by immuno histo chemistry (IHC). Analysis of a subset of these sporadic meningiomas by fluorescent in situ hybridization (FISH) with a Protein 4.1R specific probe demonstrated 100 percent concordance with the IHC results. In support of a meningioma tumor suppressor function, over expression of Protein 4.1R resulted in suppression of IOMM-Lee and CH157MN cell proliferation. Similar to the Protein 4.1B and merlin meningioma tumor suppressors, Protein 4.1R localization in the membrane fraction increased significantly under conditions of growth arrest in vitro. Lastly, Protein 4.1R interacted with some known merlin/Protein 4.1B interactors such as CD44 and bII-spectrin, but did not associate with the Protein 4.1B interactors 14-3-3 and PRMT3 or the merlin binding proteins SCHIP-1 and HRS. Collectively, these results suggest that Protein 4.1R functions as an important tumor suppressor important in the molecular pathogenesis of meningioma.

  5. Inhibition of nuclear factor-erythroid 2–related factor (Nrf2) by caveolin-1 promotes stress-induced premature senescence

    PubMed Central

    Volonte, Daniela; Liu, Zhongmin; Musille, Paul M.; Stoppani, Elena; Wakabayashi, Nobunao; Di, Yuan-Pu; Lisanti, Michael P.; Kensler, Thomas W.; Galbiati, Ferruccio

    2013-01-01

    Reactive oxygen species (ROS) can induce premature cellular senescence, which is believed to contribute to aging and age-related diseases. The nuclear erythroid 2 p45–related factor-2 (Nrf2) is a transcription factor that mediates cytoprotective responses against stress. We demonstrate that caveolin-1 is a direct binding partner of Nrf2, as shown by the binding of the scaffolding domain of caveolin-1 (amino acids 82–101) to the caveolin-binding domain of Nrf2 (amino acids 281–289). Biochemical studies show that Nrf2 is concentrated into caveolar membranes in human and mouse fibroblasts, where it colocalizes with caveolin-1, under resting conditions. After oxidative stress, caveolin-1 limits the movement of Nrf2 from caveolar membranes to the nucleus. In contrast, Nrf2 is constitutively localized to the nucleus before and after oxidative stress in caveolin-1–null mouse embryonic fibroblasts (MEFs), which do not express caveolin-1. Functional studies demonstrate that caveolin-1 acts as an endogenous inhibitor of Nrf2, as shown by the enhanced up-regulation of NQO1, an Nrf2 target gene, in caveolin-1–null MEFs and the activation or inhibition of a luciferase construct carrying an antioxidant responsive element (ARE) after down-regulation of caveolin-1 by small interfering RNA or overexpression of caveolin-1, respectively. Expression of a mutant form of Nrf2 that cannot bind to caveolin-1 (Φ→A-Nrf2) hyperactivates ARE and inhibits oxidative stress–induced activation of the p53/p21Waf1/Cip1 pathway and induction of premature senescence in fibroblasts. Finally, we show that overexpression of caveolin-1 in colon cancer cells inhibits oxidant-induced activation of Nrf2-dependent signaling, promotes premature senescence, and inhibits their transformed phenotype. Thus, by inhibiting Nrf2-mediated signaling, caveolin-1 links free radicals to the activation of the p53/senescence pathway. PMID:23637463

  6. Triptolide inhibits the migration and invasion of human prostate cancer cells via Caveolin-1/CD147/MMPs pathway.

    PubMed

    Yuan, Shiqi; Wang, Liping; Chen, Xixi; Fan, Bo; Yuan, Qingmin; Zhang, Han; Yang, Deyong; Wang, Shujing

    2016-12-01

    Prostate cancer (PCa) is the second most common type of carcinoma and the 5th leading cause of cancer-related death in males. Triptolide, is a main and effective component of Tripterygium wilfordii Hook F, which exerts an broad-spectrum anti-malignant tumor function. However, the effect of triptolide on migration and invasion of human prostate cancer cells is still poorly understood. In this study, we demonstrated that triptolide significantly inhibited the proliferation, migration and invasion of prostate cancer cells in a time- and dose-dependent manner. Caveolin-1 (Cav-1) is regarded as a major structural protein of caveolae and participated in lipid transport, signal transduction and tumor progression. Triptolide treatment inhibited the expression of tumor promoter Cav-1 and reduced CD147 and MMPs activities at both mRNA and protein levels. Meanwhile, triptolide treatment combined with Cav-1 knockdown in PCa cells enhanced the effects of anti-migration and anti-invasion, and those effects were restored following Cav-1-rescued. Together, our research indicates that triptolide represses the migration and invasion through Cav-1/CD147/MMPs pathway in PCa cells, which gives a better understanding of triptolide in clinical aggressive prostate cancer therapy.

  7. The von Hippel–Lindau tumour-suppressor protein interaction with protein kinase Cδ

    PubMed Central

    Iturrioz, Xavier; Durgan, Joanne; Calleja, Véronique; Larijani, Banafshé; Okuda, Heiwa; Whelan, Richard; Parker, Peter J.

    2006-01-01

    The VHL (von Hippel–Lindau) tumour-suppressor protein forms a multi-protein complex [VCB (pVHL–elongin C–elongin B)–Cul-2 (Cullin-2)] with elongin C, elongin B, Cul-2 and Rbx1, acting as a ubiquitin-ligase (E3) and directing proteasome-dependent degradation of targeted proteins. The α-subunit of Hif1α (hypoxia-inducible factor 1α) is the principal substrate for the VCB–Cul-2 complex; however, other substrates such as aPKC (atypical protein kinase C) have been reported. In the present study, we show with FRET (fluorescence resonance energy transfer) analysis measured by FLIM (fluorescence lifetime imaging microscopy) that PKCδ and pVHL (VHL protein) interact directly in cells. This occurs through the catalytic domain of PKCδ (residues 432–508), which appears to interact with two regions of pVHL, residues 113–122 and 130–154. Despite this robust interaction, analysis of the PMA-induced proteasome-dependent degradation of PKCδ in different RCC (renal cell carcinoma) lines (RCC4, UMRC2 and 786 O) shows that there is no correlation between the degradation of PKCδ and the presence of active pVHL. Thus, in contrast with aPKC, PKCδ is not a conventional substrate of the ubiquitin-ligase complex, VCB–Cul-2, and the observed interaction between these two proteins must underlie a distinct signalling output. PMID:16669786

  8. Internalization of the TGF-β type I receptor into caveolin-1 and EEA1 double-positive early endosomes.

    PubMed

    He, Kangmin; Yan, Xiaohua; Li, Nan; Dang, Song; Xu, Li; Zhao, Bing; Li, Zijian; Lv, Zhizhen; Fang, Xiaohong; Zhang, Youyi; Chen, Ye-Guang

    2015-06-01

    Endocytosis and intracellular sorting of transforming growth factor-β (TGF-β) receptors play an important regulatory role in TGF-β signaling. Two major endocytic pathways, clathrin- and caveolae-mediated endocytosis, have been reported to independently mediate the internalization of TGF-β receptors. In this study, we demonstrate that the clathrin- and caveolae-mediated endocytic pathways can converge during TGF-β receptor endocytic trafficking. By tracking the intracellular dynamics of fluorescently-labeled TGF-β type I receptor (TβRI), we found that after mediating TβRI internalization, certain clathrin-coated vesicles and caveolar vesicles are fused underneath the plasma membrane, forming a novel type of caveolin-1 and clathrin double-positive vesicles. Under the regulation of Rab5, the fused vesicles are targeted to early endosomes and thus deliver the internalized TβRI to the caveolin-1 and EEA1 double-positive early endosomes (caveolin-1-positive early endosomes). We further showed that the caveolin-1-positive early endosomes are positive for Smad3/SARA, Rab11 and Smad7/Smurf2, and may act as a multifunctional device for TGF-β signaling and TGF-β receptor recycling and degradation. Therefore, these findings uncover a novel scenario of endocytosis, the direct fusion of clathrin-coated and caveolae vesicles during TGF-β receptor endocytic trafficking, which leads to the formation of the multifunctional sorting device, caveolin-1-positive early endosomes, for TGF-β receptors.

  9. Internalization of the TGF-β type I receptor into caveolin-1 and EEA1 double-positive early endosomes

    PubMed Central

    He, Kangmin; Yan, Xiaohua; Li, Nan; Dang, Song; Xu, Li; Zhao, Bing; Li, Zijian; Lv, Zhizhen; Fang, Xiaohong; Zhang, Youyi; Chen, Ye-Guang

    2015-01-01

    Endocytosis and intracellular sorting of transforming growth factor-β (TGF-β) receptors play an important regulatory role in TGF-β signaling. Two major endocytic pathways, clathrin- and caveolae-mediated endocytosis, have been reported to independently mediate the internalization of TGF-β receptors. In this study, we demonstrate that the clathrin- and caveolae-mediated endocytic pathways can converge during TGF-β receptor endocytic trafficking. By tracking the intracellular dynamics of fluorescently-labeled TGF-β type I receptor (TβRI), we found that after mediating TβRI internalization, certain clathrin-coated vesicles and caveolar vesicles are fused underneath the plasma membrane, forming a novel type of caveolin-1 and clathrin double-positive vesicles. Under the regulation of Rab5, the fused vesicles are targeted to early endosomes and thus deliver the internalized TβRI to the caveolin-1 and EEA1 double-positive early endosomes (caveolin-1-positive early endosomes). We further showed that the caveolin-1-positive early endosomes are positive for Smad3/SARA, Rab11 and Smad7/Smurf2, and may act as a multifunctional device for TGF-β signaling and TGF-β receptor recycling and degradation. Therefore, these findings uncover a novel scenario of endocytosis, the direct fusion of clathrin-coated and caveolae vesicles during TGF-β receptor endocytic trafficking, which leads to the formation of the multifunctional sorting device, caveolin-1-positive early endosomes, for TGF-β receptors. PMID:25998683

  10. Functional association between Wwox tumor suppressor protein and p73, a p53 homolog.

    PubMed

    Aqeilan, Rami I; Pekarsky, Yuri; Herrero, Juan J; Palamarchuk, Alexey; Letofsky, Jean; Druck, Teresa; Trapasso, Francesco; Han, Shuang-Yin; Melino, Gerry; Huebner, Kay; Croce, Carlo M

    2004-03-30

    The WWOX gene is a recently cloned tumor suppressor gene that spans the FRA16D fragile region. Wwox protein contains two WW domains that are generally known to mediate protein-protein interaction. Here we show that Wwox physically interacts via its first WW domain with the p53 homolog, p73. The tyrosine kinase, Src, phosphorylates Wwox at tyrosine 33 in the first WW domain and enhances its binding to p73. Our results further demonstrate that Wwox expression triggers redistribution of nuclear p73 to the cytoplasm and, hence, suppresses its transcriptional activity. In addition, we show that cytoplasmic p73 contributes to the proapoptotic activity of Wwox. Our findings reveal a functional cross-talk between p73 and Wwox tumor suppressor protein.

  11. Downregulation of caveolin-1 increases the sensitivity of drug-resistant colorectal cancer HCT116 cells to 5-fluorouracil

    PubMed Central

    Li, Zhaoyang; Wang, Ning; Huang, Changxin; Bao, Yanhong; Jiang, Yiqian; Zhu, Guiting

    2017-01-01

    Colorectal cancer is the third most common type of cancer in men and women. Chemotherapy is an important treatment strategy for patients with terminal stage cancer. However, the development of drug resistance hampers the effectiveness of chemotherapy. Therefore, an effective therapeutic approach to target chemoresistance-associated cellular molecules is required. In the present study, drug-resistant human colorectal cancer HCT116 cells were developed by treating HCT116 cells with increasing concentrations of 5-fluorouracil (5-FU). The present study indicated that the drug-resistance cells (DRC) were resistant to 5-FU compared with parental HCT116 cells by detecting cell survival using an MTT assay. Additionally, the expression of the chemoresistance-associated protein caveolin-1 (Cav-1) was assessed by reverse transcription-quantitative polymerase chain reaction and western blotting. The results revealed that the Cav-1 expression level was significantly higher in DRC compared with that in the parental HCT116 cells. Next, Cav-1 was silenced by small interfering RNA (siRNA) or was inhibited with its specific inhibitor methyl β-cyclodextrin (MCD). MTT assay demonstrated that Cav-1 siRNA and MCD resensitized DRC to 5-FU. These data reveal that Cav-1 was involved in the development of resistance, suggesting that Cav-1 is a potential target for the treatment of colorectal cancer chemoresistance. In addition, 5-FU combined with Cav-1 siRNA or its specific inhibitor may increase the effectiveness of the treatment strategy. PMID:28123586

  12. DJ-1 deficiency impairs glutamate uptake into astrocytes via the regulation of flotillin-1 and caveolin-1 expression

    PubMed Central

    Kim, Jin-Mo; Cha, Seon-Heui; Choi, Yu Ree; Jou, Ilo; Joe, Eun-Hye; Park, Sang Myun

    2016-01-01

    Parkinson’s disease (PD) is a common chronic and progressive neurodegenerative disorder. Although the cause of PD is still poorly understood, mutations in many genes including SNCA, parkin, PINK1, LRRK2, and DJ-1 have been identified in the familial forms of PD. It was recently proposed that alterations in lipid rafts may cause the neurodegeneration shown in PD. Here, we observe that DJ-1 deficiency decreased the expression of flotillin-1 (flot-1) and caveolin-1 (cav-1), the main protein components of lipid rafts, in primary astrocytes and MEF cells. As a mechanism, DJ-1 regulated flot-1 stability by direct interaction, however, decreased cav-1 expression may not be a direct effect of DJ-1, but rather as a result of decreased flot-1 expression. Dysregulation of flot-1 and cav-1 by DJ-1 deficiency caused an alteration in the cellular cholesterol level, membrane fluidity, and alteration in lipid rafts-dependent endocytosis. Moreover, DJ-1 deficiency impaired glutamate uptake into astrocytes, a major function of astrocytes in the maintenance of CNS homeostasis, by altering EAAT2 expression. This study will be helpful to understand the role of DJ-1 in the pathogenesis of PD, and the modulation of lipid rafts through the regulation of flot-1 or cav-1 may be a novel therapeutic target for PD. PMID:27346864

  13. Caveolin-1 knockdown is associated with the metastasis and proliferation of human lung cancer cell line NCI-H460.

    PubMed

    Song, Yang; Xue, Liyan; Du, Sha; Sun, Mingzhong; Hu, Jun; Hao, Lihong; Gong, Linlin; Yeh, Dongmei; Xiong, Hai; Shao, Shujuan

    2012-09-01

    Caveolin-1 (CAV-1), one component of caveolae, involves in multiple cellular processes and signal transductions. We previously showed that the expression of CAV-1 gene in NCI-H446 cells inhibited cell proliferation and promoted cell metastasis. Here we explore the function of CAV-1 on tumor growth and metastasis by using NCI-H460 in vitro. First, we established NCI-H460 cell line, which CAV-1 was stably knockdown. Then we investigated the effects of CAV-1 on the morphology, proliferation, cell cycle and metastasis potential for NCI-H460 cell by crystal violet stains, CCK-8, colony formation, flow cytometry, scratch-wound assay and transwell assay. Western blot was used to examine the expression changes of cyclin D1, PCNA, E-cadherin and β-catenin. Our results showed stable knockdown of CAV-1 inhibited the proliferation of NCI-H460 cells. Cell cycle of the transfected cells was arrested in G1/S phase and the expressions of cyclin D1 and PCNA protein were downregulated. Downregulation of CAV-1 promoted the migration and invasion abilities of NCI-H460 cells in vitro. The expression of β-catenin increased and the level of E-cadherin decreased. In summary, our findings provide experimental evidence that CAV-1 may function as a proproliferative and antimetastatic gene in NCI-H460 cell line.

  14. Effects of high glucose on caveolin-1 and insulin signaling in 3T3-L1 adipocytes.

    PubMed

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Martínez, J Alfredo; de Miguel, Carlos; Milagro, Fermín I

    2016-01-01

    Adipocytes exposed to high glucose concentrations exhibit impaired metabolic function, including an increase of oxidative and proinflammatory factors that might favor the development of insulin resistance. Caveolin-1 (Cav-1) is a key mediator of the insulin transduction pathway whose expression is significantly enhanced during adipocyte differentiation. In this work, we studied the effects of high glucose concentration on the regulation of Cav-1 expression and activation and its relation to the insulin signaling pathway during the adipogenic process and in long-term differentiated adipocytes. Both, long-term high glucose exposure during adipogenesis and short-term glucose incubation of mature adipocytes, promoted triglyceride accumulation in 3T3-L1 cells. The short-term exposure of mature adipocytes to high glucose significantly reduced the sensitivity to insulin of Cav-1, insulin receptor (IR) and potein kinase B (AKT-2) phosphorylation, as well as insulin-induced deoxyglucose uptake. Adipocytes differentiated in the presence of high glucose lost Cav-1 and IR response to insulin-stimulated phosphorylation, but maintained the insulin sensitivity of AKT-2 phosphorylation and deoxyglucose uptake. Although long-term high glucose exposure increased DNA methylation in Cav-1 promoter, Cav-1 expression was not affected. Moreover, these cells showed an increase of Cav-1, IR and AKT-2 protein content, pointing to an adaptive response induced by the long-term high glucose exposure.

  15. Effects of high glucose on caveolin-1 and insulin signaling in 3T3-L1 adipocytes

    PubMed Central

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Martínez, J. Alfredo; de Miguel, Carlos; Milagro, Fermín I.

    2016-01-01

    ABSTRACT Adipocytes exposed to high glucose concentrations exhibit impaired metabolic function, including an increase of oxidative and proinflammatory factors that might favor the development of insulin resistance. Caveolin-1 (Cav-1) is a key mediator of the insulin transduction pathway whose expression is significantly enhanced during adipocyte differentiation. In this work, we studied the effects of high glucose concentration on the regulation of Cav-1 expression and activation and its relation to the insulin signaling pathway during the adipogenic process and in long-term differentiated adipocytes. Both, long-term high glucose exposure during adipogenesis and short-term glucose incubation of mature adipocytes, promoted triglyceride accumulation in 3T3-L1 cells. The short-term exposure of mature adipocytes to high glucose significantly reduced the sensitivity to insulin of Cav-1, insulin receptor (IR) and potein kinase B (AKT-2) phosphorylation, as well as insulin-induced deoxyglucose uptake. Adipocytes differentiated in the presence of high glucose lost Cav-1 and IR response to insulin-stimulated phosphorylation, but maintained the insulin sensitivity of AKT-2 phosphorylation and deoxyglucose uptake. Although long-term high glucose exposure increased DNA methylation in Cav-1 promoter, Cav-1 expression was not affected. Moreover, these cells showed an increase of Cav-1, IR and AKT-2 protein content, pointing to an adaptive response induced by the long-term high glucose exposure. PMID:27144098

  16. Modulator of Apoptosis 1 (MOAP-1) Is a Tumor Suppressor Protein Linked to the RASSF1A Protein*

    PubMed Central

    Law, Jennifer; Salla, Mohamed; Zare, Alaa; Wong, Yoke; Luong, Le; Volodko, Natalia; Svystun, Orysya; Flood, Kayla; Lim, Jonathan; Sung, Miranda; Dyck, Jason R. B.; Tan, Chong Teik; Su, Yu-Chin; Yu, Victor C.; Mackey, John; Baksh, Shairaz

    2015-01-01

    Modulator of apoptosis 1 (MOAP-1) is a BH3-like protein that plays key roles in cell death or apoptosis. It is an integral partner to the tumor suppressor protein, Ras association domain family 1A (RASSF1A), and functions to activate the Bcl-2 family pro-apoptotic protein Bax. Although RASSF1A is now considered a bona fide tumor suppressor protein, the role of MOAP-1 as a tumor suppressor protein has yet to be determined. In this study, we present several lines of evidence from cancer databases, immunoblotting of cancer cells, proliferation, and xenograft assays as well as DNA microarray analysis to demonstrate the role of MOAP-1 as a tumor suppressor protein. Frequent loss of MOAP-1 expression, in at least some cancers, appears to be attributed to mRNA down-regulation and the rapid proteasomal degradation of MOAP-1 that could be reversed utilizing the proteasome inhibitor MG132. Overexpression of MOAP-1 in several cancer cell lines resulted in reduced tumorigenesis and up-regulation of genes involved in cancer regulatory pathways that include apoptosis (p53, Fas, and MST1), DNA damage control (poly(ADP)-ribose polymerase and ataxia telangiectasia mutated), those within the cell metabolism (IR-α, IR-β, and AMP-activated protein kinase), and a stabilizing effect on microtubules. The loss of RASSF1A (an upstream regulator of MOAP-1) is one of the earliest detectable epigenetically silenced tumor suppressor proteins in cancer, and we speculate that the additional loss of function of MOAP-1 may be a second hit to functionally compromise the RASSF1A/MOAP-1 death receptor-dependent pathway and drive tumorigenesis. PMID:26269600

  17. Caveolin-1-Deficient Mice Show Defects in Innate Immunity and Inflammatory Immune Response during Salmonella enterica Serovar Typhimurium Infection▿ †

    PubMed Central

    Medina, Freddy A.; de Almeida, Cecilia J.; Dew, Elliott; Li, Jiangwei; Bonuccelli, Gloria; Williams, Terence M.; Cohen, Alex W.; Pestell, Richard G.; Frank, Philippe G.; Tanowitz, Herbert B.; Lisanti, Michael P.

    2006-01-01

    A number of studies have shown an association of pathogens with caveolae. To this date, however, there are no studies showing a role for caveolin-1 in modulating immune responses against pathogens. Interestingly, expression of caveolin-1 has been shown to occur in a regulated manner in immune cells in response to lipopolysaccharide (LPS). Here, we sought to determine the role of caveolin-1 (Cav-1) expression in Salmonella pathogenesis. Cav-1−/− mice displayed a significant decrease in survival when challenged with Salmonella enterica serovar Typhimurium. Spleen and tissue burdens were significantly higher in Cav-1−/− mice. However, infection of Cav-1−/− macrophages with serovar Typhimurium did not result in differences in bacterial invasion. In addition, Cav-1−/− mice displayed increased production of inflammatory cytokines, chemokines, and nitric oxide. Regardless of this, Cav-1−/− mice were unable to control the systemic infection of Salmonella. The increased chemokine production in Cav-1−/− mice resulted in greater infiltration of neutrophils into granulomas but did not alter the number of granulomas present. This was accompanied by increased necrosis in the liver. However, Cav-1−/− macrophages displayed increased inflammatory responses and increased nitric oxide production in vitro in response to Salmonella LPS. These results show that caveolin-1 plays a key role in regulating anti-inflammatory responses in macrophages. Taken together, these data suggest that the increased production of toxic mediators from macrophages lacking caveolin-1 is likely to be responsible for the marked susceptibility of caveolin-1-deficient mice to S. enterica serovar Typhimurium. PMID:16982844

  18. Caveolin-1 and Dopamine-Mediated Internalization of NaKATPase in Human Renal Proximal Tubule Cells

    PubMed Central

    Gildea, John J.; Israel, Jonathan A.; Johnson, Andrew K.; Zhang, Jin; Jose, Pedro A.; Felder, Robin A.

    2010-01-01

    In moderate sodium-replete states, dopamine 1–like receptors (D1R/D5R) are responsible for regulating >50% of renal sodium excretion. This is partly mediated by internalization and inactivation of NaKATPase, when associated with adapter protein 2. We used dopaminergic stimulation via fenoldopam (D1-like receptor agonist) to study the interaction among D1-like receptors, caveolin-1 (CAV1), and the G protein– coupled receptor kinase type 4 in cultured human renal proximal tubule cells (RPTCs). We compared 2 groups of RPTCs, 1 of cell lines that were isolated from normal subjects (nRPTCs) and a second group of cell lines that have D1-like receptors that are uncoupled (uncoupled RPTCs) from adenylyl cyclase second messengers. In nRPTCs, fenoldopam increased the plasma membrane expression of D1R (10.0-fold) and CAV1 (1.3-fold) and markedly decreased G protein– coupled receptor kinase type 4 by 94±8%; no effects were seen in uncoupled RPTCs. Fenoldopam also increased the association of adapter protein 2 and NaKATPase by 53±9% in nRPTCs but not in uncoupled RPTCs. When CAV1 expression was reduced by 86.0±8.5% using small interfering RNA, restimulation of the D1-like receptors with fenoldopam in nRPTCs resulted in only a 7±9% increase in association between adapter protein 2 and NaKATPase. Basal CAV1 expression and association with G protein– coupled receptor kinase type 4 was decreased in uncoupled RPTCs (58±5% decrease in association) relative to nRPTCs. We conclude that the scaffolding protein CAV1 is necessary for the association of D1-like receptors with G protein– coupled receptor kinase type 4 and the adapter protein 2-associated reduction in plasma membrane NaKATPase. PMID:19752292

  19. MYMIV-AC2, a geminiviral RNAi suppressor protein, has potential to increase the transgene expression.

    PubMed

    Rahman, Jamilur; Karjee, Sumona; Mukherjee, Sunil Kumar

    2012-06-01

    Gene silencing is one of the limiting factors for transgene expression in plants. But the plant viruses have learnt to suppress gene silencing by encoding the protein(s), called RNA silencing suppressor(s) (RSS). Hence, these proteins could be used to overcome the limitation for transgene expression. The RNAi suppressors, namely HC-Pro and P19, have been shown to enhance the transgene expression but other RSS proteins have not been screened for similar role. Moreover, none of RSSs from the DNA viruses are known for enhancing the expression of transgenes. The Mungbean Yellow Mosaic India Virus (MYMIV) belonging to the genus Begomovirus within the family of Geminiviridae encodes an RSS called the AC2 protein. Here, we used AC2 to elevate the expression of the transgenes. Upon introduction of MYMIV-AC2 in the silenced GFP transgenic tobacco lines, by either genetic hybridisation or transgenesis, the GFP expression was enhanced several fold in F1 and T0 lines. The GFP-siRNA levels were much reduced in F1 and T0 lines compared with those of the initial parental silenced lines. The enhanced GFP expression was also observed at the cellular level. This approach was also successful in enhancing the expression of another transgene, namely topoisomeraseII.

  20. Involvement of regucalcin as a suppressor protein in human carcinogenesis: insight into the gene therapy.

    PubMed

    Yamaguchi, Masayoshi

    2015-08-01

    Regucalcin, which its gene is located on the X chromosome, plays a multifunctional role as a suppressor protein in cell signal transduction in various types of cells and tissues. The suppression of regucalcin gene expression has been shown to involve in carcinogenesis. Regucalcin gene expression was uniquely downregulated in carcinogenesis of rat liver in vivo, although the expression of other many genes was upregulated, indicating that endogenous regucalcin plays a suppressive role in the development of hepatocarcinogenesis. Overexpression of endogenous regucalcin was found to suppress proliferation of rat cloned hepatoma cells in vitro. Moreover, the regucalcin gene and its protein levels were demonstrated specifically to downregulate in human hepatocellular carcinoma by analysis with multiple gene expression profiles and proteomics. Regucalcin gene expression was also found to suppress in human tumor tissues including kidney, lung, brain, breast and prostate, suggesting that repressed regucalcin gene expression leads to the development of carcinogenesis in various tissues. Regucalcin may play a role as a suppressor protein in carcinogenesis. Overexpression of endogenous regucalcin is suggested to reveal preventive and therapeutic effects on carcinogenesis. Delivery of the regucalcin gene may be a novel useful tool in the gene therapy of carcinogenesis. This review will discuss regarding to an involvement of regucalcin as a suppressor protein in human carcinogenesis in insight into the gene therapy.

  1. Interplay between hepatic mitochondria-associated membranes, lipid metabolism and caveolin-1 in mice

    PubMed Central

    Sala-Vila, Aleix; Navarro-Lérida, Inmaculada; Sánchez-Alvarez, Miguel; Bosch, Marta; Calvo, Carlos; López, Juan Antonio; Calvo, Enrique; Ferguson, Charles; Giacomello, Marta; Serafini, Annalisa; Scorrano, Luca; Enriquez, José Antonio; Balsinde, Jesús; Parton, Robert G.; Vázquez, Jesús; Pol, Albert; Del Pozo, Miguel A.

    2016-01-01

    The mitochondria-associated membrane (MAM) is a specialized subdomain of the endoplasmic reticulum (ER) which acts as an intracellular signaling hub. MAM dysfunction has been related to liver disease. We report a high-throughput mass spectrometry-based proteomics characterization of MAMs from mouse liver, which portrays them as an extremely complex compartment involved in different metabolic processes, including steroid metabolism. Interestingly, we identified caveolin-1 (CAV1) as an integral component of hepatic MAMs, which determine the relative cholesterol content of these ER subdomains. Finally, a detailed comparative proteomics analysis between MAMs from wild type and CAV1-deficient mice suggests that functional CAV1 contributes to the recruitment and regulation of intracellular steroid and lipoprotein metabolism-related processes accrued at MAMs. The potential impact of these novel aspects of CAV1 biology on global cell homeostasis and disease is discussed. PMID:27272971

  2. Interplay between hepatic mitochondria-associated membranes, lipid metabolism and caveolin-1 in mice.

    PubMed

    Sala-Vila, Aleix; Navarro-Lérida, Inmaculada; Sánchez-Alvarez, Miguel; Bosch, Marta; Calvo, Carlos; López, Juan Antonio; Calvo, Enrique; Ferguson, Charles; Giacomello, Marta; Serafini, Annalisa; Scorrano, Luca; Enriquez, José Antonio; Balsinde, Jesús; Parton, Robert G; Vázquez, Jesús; Pol, Albert; Del Pozo, Miguel A

    2016-06-06

    The mitochondria-associated membrane (MAM) is a specialized subdomain of the endoplasmic reticulum (ER) which acts as an intracellular signaling hub. MAM dysfunction has been related to liver disease. We report a high-throughput mass spectrometry-based proteomics characterization of MAMs from mouse liver, which portrays them as an extremely complex compartment involved in different metabolic processes, including steroid metabolism. Interestingly, we identified caveolin-1 (CAV1) as an integral component of hepatic MAMs, which determine the relative cholesterol content of these ER subdomains. Finally, a detailed comparative proteomics analysis between MAMs from wild type and CAV1-deficient mice suggests that functional CAV1 contributes to the recruitment and regulation of intracellular steroid and lipoprotein metabolism-related processes accrued at MAMs. The potential impact of these novel aspects of CAV1 biology on global cell homeostasis and disease is discussed.

  3. Regulation of protein phosphatase 2A (PP2A) tumor suppressor function by PME-1.

    PubMed

    Kaur, Amanpreet; Westermarck, Jukka

    2016-12-15

    Protein phosphatase 2A (PP2A) plays a major role in maintaining cellular signaling homeostasis by dephosphorylation of a variety of signaling proteins and acts as a tumor suppressor. Protein phosphatase methylesterase-1 (PME-1) negatively regulates PP2A activity by highly complex mechanisms that are reviewed here. Importantly, recent studies have shown that PME-1 promotes oncogenic MAPK/ERK and AKT pathway activities in various cancer types. In human glioma, high PME-1 expression correlates with tumor progression and kinase inhibitor resistance. We discuss the emerging cancer-associated function of PME-1 and its potential clinical relevance.

  4. Probing the U-Shaped Conformation of Caveolin-1 in a Bilayer

    PubMed Central

    Rui, Huan; Root, Kyle T.; Lee, Jinwoo; Glover, Kerney Jebrell; Im, Wonpil

    2014-01-01

    Caveolin induces membrane curvature and drives the formation of caveolae that participate in many crucial cell functions such as endocytosis. The central portion of caveolin-1 contains two helices (H1 and H2) connected by a three-residue break with both N- and C-termini exposed to the cytoplasm. Although a U-shaped configuration is assumed based on its inaccessibility by extracellular matrix probes, caveolin structure in a bilayer remains elusive. This work aims to characterize the structure and dynamics of caveolin-1 (D82–S136; Cav182–136) in a DMPC bilayer using NMR, fluorescence emission measurements, and molecular dynamics simulations. The secondary structure of Cav182–136 from NMR chemical shift indexing analysis serves as a guideline for generating initial structural models. Fifty independent molecular dynamics simulations (100 ns each) are performed to identify its favorable conformation and orientation in the bilayer. A representative configuration was chosen from these multiple simulations and simulated for 1 μs to further explore its stability and dynamics. The results of these simulations mirror those from the tryptophan fluorescence measurements (i.e., Cav182–136 insertion depth in the bilayer), corroborate that Cav182–136 inserts in the membrane with U-shaped conformations, and show that the angle between H1 and H2 ranges from 35 to 69°, and the tilt angle of Cav182–136 is 27 ± 6°. The simulations also reveal that specific faces of H1 and H2 prefer to interact with each other and with lipid molecules, and these interactions stabilize the U-shaped conformation. PMID:24655512

  5. Developmental iodine deficiency and hypothyroidism impair neural development, upregulate caveolin-1, and downregulate synaptotagmin-1 in the rat cerebellum.

    PubMed

    Wang, Yi; Zhong, Jiapeng; Wei, Wei; Gong, Jian; Dong, Jing; Yu, Fei; Wang, Yuan; Chen, Jie

    2011-12-01

    Adequate thyroid hormone is critical for cerebellar development. Developmental hypothyroidism induced by iodine deficiency during gestation and postnatal period results in permanent impairments of cerebellar development with an unclear mechanism. In the present study, we implicate cerebellar caveolin-1 and synaptotagmin-1, the two important molecules involved in neuronal development, in developmental iodine deficiency, and in developmental hypothyroidism. Two developmental rat models were created by administrating dam rats with either iodine-deficient diet or propylthiouracil (PTU, 5 or 15 ppm)-added drinking water from gestational day 6 till postnatal day (PN) 28. Nissl staining and the levels of caveolin-1 and synaptotagmin-1 in cerebella were assessed on PN28 and PN42. The results show that the numbers of Purkinje cells were reduced in the iodine-deficient and PTU-treated rats. The upregulation of caveolin-1 and the downregulation of synaptotagmin-1 were observed in both iodine-deficient and PTU-treated rats. These findings may implicate decreases in the number of Purkinje cells and the alterations in the levels of caveolin-1 and synaptotagmin-1 in the impairments of cerebellar development induced by developmental iodine deficiency and hypothyroidism.

  6. Caveolin-1 plays a key role in the oleanolic acid-induced apoptosis of HL-60 cells.

    PubMed

    Ma, Wei; Wang, Di-Di; Li, Li; Feng, Yu-Kuan; Gu, Hong-Mei; Zhu, Gui-Ming; Piao, Jin-Hua; Yang, Yu; Gao, Xu; Zhang, Peng-Xia

    2014-07-01

    Our previous study found that caveolin-1 (CAV-1) protein expression is upregulated during oleanolic acid (OA)-induced inhibition of proliferation and promotion of apoptosis in HL-60 cells. CAV-1 is the main structural protein component of caveolae, playing important roles in tumorigenesis and tumor development. It has been shown that cav-1 expression is lower in leukemia cancer cell lines SUP-B15, HL-60, THP-1 and K562 and in chronic lymphocytic leukemia primary (CLP) cells when compared with normal white blood cells, with the lowest cav-1 expression level found in HL-60 cells. To study the effects of cav-1 in HL-60 cells and the effects of cav-1 overexpression on OA drug efficacy, cav-1 was overexpressed in HL-60 cells using lentiviral-mediated transfection combined with OA treatment. The results showed that cav-1 overexpression inhibited HL-60 cell proliferation, promoted apoptosis, arrested the cell cycle in the G1 phase and inhibited activation of the PI3K/AKT/mTOR signaling pathway. Overexpression of CAV-1 also increased HL-60 cell sensitivity to OA. To further verify whether OA affects HL-60 cells via the activation of downstream signaling pathways by CAV-1, cav-1 gene expression was silenced using RNAi, and the cells were treated with OA to examine its efficacy. The results showed that after cav-1 silencing, OA had little effect on cell activity, apoptosis, the cell cycle and phosphorylation of HL-60 cells. This study is the first to show that CAV-1 plays a crucial role in the effects of OA on HL-60 cells.

  7. Inflammatory cytokines induce phosphorylation and ubiquitination of prostate suppressor protein NKX3.1.

    PubMed

    Markowski, Mark C; Bowen, Cai; Gelmann, Edward P

    2008-09-01

    Inflammation of the prostate is a risk factor for the development of prostate cancer. In the aging prostate, regions of inflammatory atrophy are foci for prostate epithelial cell transformation. Expression of the suppressor protein NKX3.1 is reduced in regions of inflammatory atrophy and in preinvasive prostate cancer. Inflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin-1beta accelerate NKX3.1 protein loss by inducing rapid ubiquitination and proteasomal degradation. The effect of TNF-alpha is mediated via the COOH-terminal domain of NKX3.1 where phosphorylation of serine 196 is critical for cytokine-induced degradation. Mutation of serine 196 to alanine abrogates phosphorylation at that site and the effect of TNF-alpha on NKX3.1 ubiquitination and protein loss. This is in contrast to control of steady-state NKX3.1 turnover, which is mediated by serine 185. Mutation of serine 185 to alanine increases NKX3.1 protein stability by inhibiting ubiquitination and doubling the protein half-life. A third COOH-terminal serine at position 195 has a modulating effect on both steady-state protein turnover and on ubiquitination induced by TNF-alpha. Thus, cellular levels of the NKX3.1 tumor suppressor are affected by inflammatory cytokines that target COOH-terminal serine residues to activate ubiquitination and protein degradation. Our data suggest that strategies to inhibit inflammation or to inhibit effector kinases may be useful approaches to prostate cancer prevention.

  8. Increased PDE5 activity and decreased Rho kinase and PKC activities in colonic muscle from caveolin-1-/- mice impair the peristaltic reflex and propulsion.

    PubMed

    Mahavadi, Sunila; Bhattacharya, Sayak; Kumar, Divya P; Clay, Chereena; Ross, Gracious; Akbarali, Hamid I; Grider, John R; Murthy, Karnam S

    2013-12-01

    Caveolae are specialized regions of the plasma membrane that concentrate receptors and associated signaling molecules critical in regulation of cellular response to transmitters and hormones. We have determined the effects of caveolin-1 (Cav-1) deletion, caveolin-1 siRNA, and caveolar disruption in mice on the signaling pathways that mediate contraction and relaxation in colonic smooth muscle and on the components of the peristaltic reflex in isolated tissue and propulsion in intact colonic segments. In Cav-1-/- mice, both relaxation and contraction were decreased in smooth muscle cells and muscle strips, as well as during both phases of the peristaltic reflex and colonic propulsion. The decrease in relaxation in response to the nitric oxide (NO) donor was accompanied by a decrease in cGMP levels and an increase in phosphodiesterase 5 (PDE5) activity. Relaxation by a PDE5-resistant cGMP analog was not affected in smooth muscle of Cav-1-/- mice, suggesting that inhibition of relaxation was due to augmentation of PDE5 activity. Similar effects on relaxation, PDE5 and cGMP were obtained in muscle cells upon disruption of caveolae by methyl-β-cyclodextrin or suppression of Cav-1. Sustained contraction mediated via inhibition of myosin light chain phosphatase (MLCP) activity is regulated by Rho kinase and PKC via phosphorylation of two endogenous inhibitors of MLCP: myosin phosphatase-targeting subunit (MYPT1) and 17-kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17), respectively. The activity of both enzymes and phosphorylation of MYPT1 and CPI-17 were decreased in smooth muscle from Cav-1-/- mice. We conclude that the integrity of caveolae is essential for contractile and relaxant activity in colonic smooth muscle and the maintenance of neuromuscular function at organ level.

  9. Increased PDE5 activity and decreased Rho kinase and PKC activities in colonic muscle from caveolin-1−/− mice impair the peristaltic reflex and propulsion

    PubMed Central

    Mahavadi, Sunila; Bhattacharya, Sayak; Kumar, Divya P.; Clay, Chereena; Ross, Gracious; Akbarali, Hamid I.; Grider, John R.

    2013-01-01

    Caveolae are specialized regions of the plasma membrane that concentrate receptors and associated signaling molecules critical in regulation of cellular response to transmitters and hormones. We have determined the effects of caveolin-1 (Cav-1) deletion, caveolin-1 siRNA, and caveolar disruption in mice on the signaling pathways that mediate contraction and relaxation in colonic smooth muscle and on the components of the peristaltic reflex in isolated tissue and propulsion in intact colonic segments. In Cav-1−/− mice, both relaxation and contraction were decreased in smooth muscle cells and muscle strips, as well as during both phases of the peristaltic reflex and colonic propulsion. The decrease in relaxation in response to the nitric oxide (NO) donor was accompanied by a decrease in cGMP levels and an increase in phosphodiesterase 5 (PDE5) activity. Relaxation by a PDE5-resistant cGMP analog was not affected in smooth muscle of Cav-1−/− mice, suggesting that inhibition of relaxation was due to augmentation of PDE5 activity. Similar effects on relaxation, PDE5 and cGMP were obtained in muscle cells upon disruption of caveolae by methyl-β-cyclodextrin or suppression of Cav-1. Sustained contraction mediated via inhibition of myosin light chain phosphatase (MLCP) activity is regulated by Rho kinase and PKC via phosphorylation of two endogenous inhibitors of MLCP: myosin phosphatase-targeting subunit (MYPT1) and 17-kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17), respectively. The activity of both enzymes and phosphorylation of MYPT1 and CPI-17 were decreased in smooth muscle from Cav-1−/− mice. We conclude that the integrity of caveolae is essential for contractile and relaxant activity in colonic smooth muscle and the maintenance of neuromuscular function at organ level. PMID:24157969

  10. Reduced caveolin-1 promotes hyper-inflammation due to abnormal heme oxygenase-1 localizationin LPS challenged macrophages with dysfunctional CFTR

    PubMed Central

    Zhang, Ping-Xia; Murray, Thomas S.; Villella, Valeria Rachela; Ferrari, Eleonora; Esposito, Speranza; D'Souza, Anthony; Raia, Valeria; Maiuri, Luigi; Krause, Diane S.; Egan, Marie E.; Bruscia, Emanuela M.

    2013-01-01

    We have previously reported that TLR4 signaling is increased in lipopolysaccharide (LPS) -stimulated Cystic Fibrosis (CF) macrophages (MΦs), contributing to the robust production of pro-inflammatory cytokines. The heme oxygenase (HO-1)/carbon monoxide (CO) pathway modulates cellular redox status, inflammatory responses, and cell survival. The HO-1 enzyme, together with the scaffold protein caveolin 1 (CAV-1), also acts as a negative regulator of TLR4 signaling in MΦs. Here, we demonstrate that in LPS-challenged CF MΦs, HO-1 does not compartmentalize normally to the cell surface and instead accumulates intracellularly. The abnormal HO-1 localization in CF MΦs in response to LPS is due to decreased CAV-1 expression, which is controlled by the cellular oxidative state, and is required for HO-1 delivery to the cell surface. Overexpression of HO-1 or stimulating the pathway with CO-releasing molecules (CORM2)enhancesCAV-1 expression in CF MΦs, suggesting a positive-feed forward loop between HO-1/CO induction and CAV-1 expression. These manipulations reestablished HO-1 and CAV-1 cell surface localization in CF MΦ's. Consistent with restoration of HO-1/CAV-1 negative regulation of TLR4 signaling, genetic or pharmacological (CORM2)-induced enhancement of this pathway decreased the inflammatory response of CF MΦs and CF mice treated with LPS. In conclusion, our results demonstrate that the counter-regulatory HO-1/CO pathway, which is critical in balancing and limiting the inflammatory response, is defective in CF MΦs through a CAV-1-dependent mechanism, exacerbating the CF MΦ's response to LPS. This pathway could be a potential target for therapeutic intervention for CF lung disease. PMID:23606537

  11. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma.

    PubMed

    Egawa, Junji; Schilling, Jan M; Cui, Weihua; Posadas, Edmund; Sawada, Atsushi; Alas, Basheer; Zemljic-Harpf, Alice E; Fannon-Pavlich, McKenzie J; Mandyam, Chitra D; Roth, David M; Patel, Hemal H; Patel, Piyush M; Head, Brian P

    2017-08-01

    Studies in vitro and in vivo demonstrate that membrane/lipid rafts and caveolin (Cav) organize progrowth receptors, and, when overexpressed specifically in neurons, Cav-1 augments neuronal signaling and growth and improves cognitive function in adult and aged mice; however, whether neuronal Cav-1 overexpression can preserve motor and cognitive function in the brain trauma setting is unknown. Here, we generated a neuron-targeted Cav-1-overexpressing transgenic (Tg) mouse [synapsin-driven Cav-1 (SynCav1 Tg)] and subjected it to a controlled cortical impact model of brain trauma and measured biochemical, anatomic, and behavioral changes. SynCav1 Tg mice exhibited increased hippocampal expression of Cav-1 and membrane/lipid raft localization of postsynaptic density protein 95, NMDA receptor, and tropomyosin receptor kinase B. When subjected to a controlled cortical impact, SynCav1 Tg mice demonstrated preserved hippocampus-dependent fear learning and memory, improved motor function recovery, and decreased brain lesion volume compared with wild-type controls. Neuron-targeted overexpression of Cav-1 in the adult brain prevents hippocampus-dependent learning and memory deficits, restores motor function after brain trauma, and decreases brain lesion size induced by trauma. Our findings demonstrate that neuron-targeted Cav-1 can be used as a novel therapeutic strategy to restore brain function and prevent trauma-associated maladaptive plasticity.-Egawa, J., Schilling, J. M., Cui, W., Posadas, E., Sawada, A., Alas, B., Zemljic-Harpf, A. E., Fannon-Pavlich, M. J., Mandyam, C. D., Roth, D. M., Patel, H. H., Patel, P. M., Head, B. P. Neuron-specific caveolin-1 overexpression improves motor function and preserves memory in mice subjected to brain trauma. © FASEB.

  12. Nitric Oxide Interacts with Caveolin-1 to Facilitate Autophagy-Lysosome-Mediated Claudin-5 Degradation in Oxygen-Glucose Deprivation-Treated Endothelial Cells

    PubMed Central

    Liu, Jie; Weaver, John; Jin, Xinchun; Zhang, Yuan; Xu, Ji; Liu, Ke J.; Li, Weiping; Liu, Wenlan

    2017-01-01

    Using in vitro oxygen-glucose deprivation (OGD) model, we have previously demonstrated that 2-h OGD induces rapid, caveolin-1-mediated dissociation of claudin-5 from the cellular cytoskeletal framework and quick endothelial barrier disruption. In this study, we further investigated the fate of translocated claudin-5 and the mechanisms by which OGD promotes caveolin-1 translocation. Exposure of bEND3 cells to 4-h OGD, but not 2-h OGD plus 2-h reoxygenation, resulted in claudin-5 degradation. Inhibition of autophagy or the fusion of autophagosome with lysosome, but not proteasome, blocked OGD-induced claudin-5 degradation. Moreover, knockdown of caveolin-1 with siRNA blocked OGD-induced claudin-5 degradation. Western blot analysis showed a transient colocalization of caveolin-1, claudin-5, and LC3B in autolysosome or lipid raft fractions at 2-h OGD. Of note, inhibiting autophagosome and lysosome fusion sustained the colocalization of caveolin-1, claudin-5, and LC3B throughout the 4-h OGD exposure. EPR spin trapping showed increased nitric oxide (NO) generation in 2-h OGD-treated cells, and inhibiting NO with its scavenger C-PTIO or inducible nitric oxide synthase (iNOS) inhibitor 1400W prevented OGD-induced caveolin-1 translocation and claudin-5 degradation. Taken together, our data provide a novel mechanism underlying endothelial barrier disruption under prolonged ischemic conditions, in which NO promotes caveolin-1-mediated delivery of claudin-5 to the autophagosome for autophagy-lysosome-dependent degradation. PMID:26515186

  13. Nitric Oxide Interacts with Caveolin-1 to Facilitate Autophagy-Lysosome-Mediated Claudin-5 Degradation in Oxygen-Glucose Deprivation-Treated Endothelial Cells.

    PubMed

    Liu, Jie; Weaver, John; Jin, Xinchun; Zhang, Yuan; Xu, Ji; Liu, Ke J; Li, Weiping; Liu, Wenlan

    2016-11-01

    Using in vitro oxygen-glucose deprivation (OGD) model, we have previously demonstrated that 2-h OGD induces rapid, caveolin-1-mediated dissociation of claudin-5 from the cellular cytoskeletal framework and quick endothelial barrier disruption. In this study, we further investigated the fate of translocated claudin-5 and the mechanisms by which OGD promotes caveolin-1 translocation. Exposure of bEND3 cells to 4-h OGD, but not 2-h OGD plus 2-h reoxygenation, resulted in claudin-5 degradation. Inhibition of autophagy or the fusion of autophagosome with lysosome, but not proteasome, blocked OGD-induced claudin-5 degradation. Moreover, knockdown of caveolin-1 with siRNA blocked OGD-induced claudin-5 degradation. Western blot analysis showed a transient colocalization of caveolin-1, claudin-5, and LC3B in autolysosome or lipid raft fractions at 2-h OGD. Of note, inhibiting autophagosome and lysosome fusion sustained the colocalization of caveolin-1, claudin-5, and LC3B throughout the 4-h OGD exposure. EPR spin trapping showed increased nitric oxide (NO) generation in 2-h OGD-treated cells, and inhibiting NO with its scavenger C-PTIO or inducible nitric oxide synthase (iNOS) inhibitor 1400W prevented OGD-induced caveolin-1 translocation and claudin-5 degradation. Taken together, our data provide a novel mechanism underlying endothelial barrier disruption under prolonged ischemic conditions, in which NO promotes caveolin-1-mediated delivery of claudin-5 to the autophagosome for autophagy-lysosome-dependent degradation.

  14. The Ebola virus VP35 protein is a suppressor of RNA silencing.

    PubMed

    Haasnoot, Joost; de Vries, Walter; Geutjes, Ernst-Jan; Prins, Marcel; de Haan, Peter; Berkhout, Ben

    2007-06-01

    RNA silencing or interference (RNAi) is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is triggered by virus-specific double-stranded RNA molecules (dsRNAs) that are produced during infection. To overcome antiviral RNAi responses, many plant and insect viruses encode RNA silencing suppressors (RSSs) that enable them to replicate at higher titers. Recently, several human viruses were shown to encode RSSs, suggesting that RNAi also serves as an innate defence response in mammals. Here, we demonstrate that the Ebola virus VP35 protein is a suppressor of RNAi in mammalian cells and that its RSS activity is functionally equivalent to that of the HIV-1 Tat protein. We show that VP35 can replace HIV-1 Tat and thereby support the replication of a Tat-minus HIV-1 variant. The VP35 dsRNA-binding domain is required for this RSS activity. Vaccinia virus E3L protein and influenza A virus NS1 protein are also capable of replacing the HIV-1 Tat RSS function. These findings support the hypothesis that RNAi is part of the innate antiviral response in mammalian cells. Moreover, the results indicate that RSSs play a critical role in mammalian virus replication.

  15. The Ebola Virus VP35 Protein Is a Suppressor of RNA Silencing

    PubMed Central

    Geutjes, Ernst-Jan; Prins, Marcel; de Haan, Peter; Berkhout, Ben

    2007-01-01

    RNA silencing or interference (RNAi) is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is triggered by virus-specific double-stranded RNA molecules (dsRNAs) that are produced during infection. To overcome antiviral RNAi responses, many plant and insect viruses encode RNA silencing suppressors (RSSs) that enable them to replicate at higher titers. Recently, several human viruses were shown to encode RSSs, suggesting that RNAi also serves as an innate defence response in mammals. Here, we demonstrate that the Ebola virus VP35 protein is a suppressor of RNAi in mammalian cells and that its RSS activity is functionally equivalent to that of the HIV-1 Tat protein. We show that VP35 can replace HIV-1 Tat and thereby support the replication of a Tat-minus HIV-1 variant. The VP35 dsRNA-binding domain is required for this RSS activity. Vaccinia virus E3L protein and influenza A virus NS1 protein are also capable of replacing the HIV-1 Tat RSS function. These findings support the hypothesis that RNAi is part of the innate antiviral response in mammalian cells. Moreover, the results indicate that RSSs play a critical role in mammalian virus replication. PMID:17590081

  16. Hydroxylation-Dependent Interaction of Substrates to the Von Hippel-Lindau Tumor Suppressor Protein (VHL).

    PubMed

    Heir, Pardeep; Ohh, Michael

    2016-01-01

    Oxygen-dependent hydroxylation of critical proline residues, catalyzed by prolyl hydroxylase (PHD1-3) enzymes, is a crucial posttranslational modification (PTM) within the canonical hypoxia-inducible factor (HIF)-centric cellular oxygen-sensing pathway. Alteration of substrates in this way often leads to proteasomal degradation mediated by the von Hippel-Lindau Tumor Suppressor protein (VHL) containing E3-ubiquitin ligase complex known as ECV (Elongins B/C, CUL2, VHL). Here, we outline in vitro protocols to demonstrate the ability of VHL to bind to a prolyl-hydroxylated substrate.

  17. Suppressors of the Chloroplast Protein Import Mutant tic40 Reveal a Genetic Link between Protein Import and Thylakoid Biogenesis.

    PubMed

    Bédard, Jocelyn; Trösch, Raphael; Wu, Feijie; Ling, Qihua; Flores-Pérez, Úrsula; Töpel, Mats; Nawaz, Fahim; Jarvis, Paul

    2017-07-01

    To extend our understanding of chloroplast protein import and the role played by the import machinery component Tic40, we performed a genetic screen for suppressors of chlorotic tic40 knockout mutant Arabidopsis thaliana plants. As a result, two suppressor of tic40 loci, stic1 and stic2, were identified and characterized. The stic1 locus corresponds to the gene ALBINO4 (ALB4), which encodes a paralog of the well-known thylakoid protein targeting factor ALB3. The stic2 locus identified a previously unknown stromal protein that interacts physically with both ALB4 and ALB3. Genetic studies showed that ALB4 and STIC2 act together in a common pathway that also involves cpSRP54 and cpFtsY. Thus, we conclude that ALB4 and STIC2 both participate in thylakoid protein targeting, potentially for a specific subset of thylakoidal proteins, and that this targeting pathway becomes disadvantageous to the plant in the absence of Tic40. As the stic1 and stic2 mutants both suppressed tic40 specifically (other TIC-related mutants were not suppressed), we hypothesize that Tic40 is a multifunctional protein that, in addition to its originally described role in protein import, is able to influence downstream processes leading to thylakoid biogenesis. © 2017 American Society of Plant Biologists. All rights reserved.

  18. The structure of p53 tumour suppressor protein reveals the basis for its functional plasticity

    PubMed Central

    Okorokov, Andrei L; Sherman, Michael B; Plisson, Celia; Grinkevich, Vera; Sigmundsson, Kristmundur; Selivanova, Galina; Milner, Jo; Orlova, Elena V

    2006-01-01

    p53 major tumour suppressor protein has presented a challenge for structural biology for two decades. The intact and complete p53 molecule has eluded previous attempts to obtain its structure, largely due to the intrinsic flexibility of the protein. Using ATP-stabilised p53, we have employed cryoelectron microscopy and single particle analysis to solve the first three-dimensional structure of the full-length p53 tetramer (resolution 13.7 Å). The p53 molecule is a D2 tetramer, resembling a hollow skewed cube with node-like vertices of two sizes. Four larger nodes accommodate central core domains, as was demonstrated by fitting of its X-ray structure. The p53 monomers are connected via their juxtaposed N- and C-termini within smaller N/C nodes to form dimers. The dimers form tetramers through the contacts between core nodes and N/C nodes. This structure revolutionises existing concepts of p53's molecular organisation and resolves conflicting data relating to its biochemical properties. This architecture of p53 in toto suggests novel mechanisms for structural plasticity, which enables the protein to bind variably spaced DNA target sequences, essential for p53 transactivation and tumour suppressor functions. PMID:17053786

  19. Mobility of the von Hippel-Lindau tumour suppressor protein is regulated by kinesin-2.

    PubMed

    Mans, Dorus A; Lolkema, Martijn P; van Beest, Moniek; Daenen, Laura G; Voest, Emile E; Giles, Rachel H

    2008-04-01

    The von Hippel-Lindau tumour suppressor protein (pVHL) participates in many cellular processes including oxygen sensing, microtubule stability and primary cilia regulation. Recently, we identified ATP-dependent motor complex kinesin-2 to endogenously bind the full-length variant of VHL (pVHL30) in primary kidney cells, and mediate its association to microtubules. Here we show that pVHL also endogenously binds the neuronal kinesin-2 complex, which slightly differs from renal kinesin-2. To investigate the role of kinesin-2 in pVHL mobility, we performed fluorescence recovery after photobleaching (FRAP) experiments in neuroblastoma cells. We observe that pVHL30 is a highly mobile cytoplasmic protein, which becomes an immobile centrosomal protein after ATP-depletion in living cells. This response to ATP-depletion is independent of GSK3beta-dependent phosphorylation of pVHL30. Furthermore, VHL variant alleles with reduced binding to kinesin-2 fail to respond to ATP-depletion. Accordingly, interfering with pVHL30-KIF3A interaction by either overexpressing a dominant negative construct or by reducing endogenous cellular levels of KIF3A by RNAi abolishes pVHL's response to ATP-depletion. From these data we suggest that mobility of a subcellular pool of pVHL is regulated by the ATP-dependent kinesin-2 motor. Kinesin-2 driven mobility of cytoplasmic pVHL might enable pVHL to function as a tumour suppressor.

  20. [HINT1--a novel tumor suppressor protein of the HIT superfamily].

    PubMed

    Ozga, Magdalena

    2010-01-01

    The histidine triad nucleotide binding protein1 (Hint1) belongs to the first branch of the HIT superfamily. Hint1 catalyses the process of hydrolysis of the P-N bond in AMP-lysine, AMP-alanine, AMP-NH2. The physiological role of this enzyme is still unclear. There is accumulating evidence that HINT1 is a novel tumor suppressor protein, albeit the mechanism of action of HINT1 in respect to tumor suppression is not fully understood. Recent findings have shown that Hint1 inhibits the activity of the transcription factors AP1, MITF and USF2, as well as influences the transcription process of some genes of Wnt/beta-catenin pathway. Thereby, it seems that Hint1 exerts its major cellular function as gene transcription regulator, and thus, this function provides its potential role as a tumor suppressor protein. The clinical relevance of impairments in the Hint1 expression with the respect to specific human cancers is still a matter of extensive studies.

  1. Genetic evidence supporting a critical role of endothelial caveolin-1 during the progression of atherosclerosis

    PubMed Central

    Fernández-Hernando, Carlos; Yu, Jun; Suárez, Yajaira; Rahner, Christoph; Dávalos, Alberto; Lasunción, Miguel A.; Sessa, William C.

    2009-01-01

    SUMMARY The accumulation of LDL-derived cholesterol in the artery wall is the initiating event that causes atherosclerosis. However, the mechanisms that lead to the initiation of atherosclerosis are still poorly understood. Here, by using endothelial cell-specific transgenesis of the caveolin-1 (Cav-1) gene in mice, we show the critical role of Cav-1 in promoting atherogenesis. Mice were generated lacking Cav-1 and apoE but expressing endothelial-specific Cav-1 in the double knockout background. Genetic ablation of Cav-1 on an apoE knockout background inhibits the progression of atherosclerosis while re-expression of Cav-1 in the endothelium promotes lesion expansion. Mechanistically, the loss of Cav-1 reduces LDL infiltration into the artery wall, promotes nitric oxide production and reduces the expression of leukocyte adhesion molecules, effects completely reversed in transgenic mice. In summary, this unique model provides physiological evidence supporting the important role of endothelial Cav-1 expression in regulating the entry of LDL into the vessel wall and the initiation of atherosclerosis. PMID:19583953

  2. Growth suppression by ursodeoxycholic acid involves caveolin-1 enhanced degradation of EGFR

    PubMed Central

    Feldman, Rebecca; Martinez, Jesse D.

    2009-01-01

    Summary Ursodeoxycholic acid (UDCA) has been shown to prevent colon tumorigenesis in animal models and in humans. In vitro work indicates that this bile acid can suppress cell growth and mitogenic signaling suggesting that UDCA may be an anti-proliferative agent. However, the mechanism by which UDCA functions is unclear. Previously we showed that bile acids may alter cellular signaling by acting at the plasma membrane. Here we utilized EGFR as a model membrane receptor and examined the effects that UDCA has on its functioning. We found that UDCA promoted an interaction between EGFR and caveolin-1 and this interaction enhanced UDCA-mediated suppression of MAP kinase activity and cell growth . Importantly, UDCA treatment led to recruitment of the ubiquitin ligase, c-Cbl, to the membrane, ubiquitination of EGFR, and increased receptor degradation. Moreover, suppression of c-Cbl activity abrogated UDCA's growth suppression activities suggesting that receptor ubiquitination plays an important role in UDCA's biological activities. Taken together these results suggest that UDCA may act to suppress cell growth by inhibiting the mitogenic activity of receptor tyrosine kinases such as EGFR through increased receptor degradation. PMID:19446582

  3. E-cadherin determines Caveolin-1 tumor suppression or metastasis enhancing function in melanoma cells.

    PubMed

    Lobos-González, Lorena; Aguilar, Lorena; Diaz, Jorge; Diaz, Natalia; Urra, Hery; Torres, Vicente A; Silva, Veronica; Fitzpatrick, Christopher; Lladser, Alvaro; Hoek, Keith S; Leyton, Lisette; Quest, Andrew F G

    2013-07-01

    The role of caveolin-1 (CAV1) in cancer is highly controversial. CAV1 suppresses genes that favor tumor development, yet also promotes focal adhesion turnover and migration of metastatic cells. How these contrasting observations relate to CAV1 function in vivo is unclear. Our previous studies implicate E-cadherin in CAV1-dependent tumor suppression. Here, we use murine melanoma B16F10 cells, with low levels of endogenous CAV1 and E-cadherin, to unravel how CAV1 affects tumor growth and metastasis and to assess how co-expression of E-cadherin modulates CAV1 function in vivo in C57BL/6 mice. We find that overexpression of CAV1 in B16F10 (cav-1) cells reduces subcutaneous tumor formation, but enhances metastasis relative to control cells. Furthermore, E-cadherin expression in B16F10 (E-cad) cells reduces subcutaneous tumor formation and lung metastasis when intravenously injected. Importantly, co-expression of CAV1 and E-cadherin in B16F10 (cav-1/E-cad) cells abolishes tumor formation, lung metastasis, increased Rac-1 activity, and cell migration observed with B16F10 (cav-1) cells. Finally, consistent with the notion that CAV1 participates in switching human melanomas to a more malignant phenotype, elevated levels of CAV1 expression correlated with enhanced migration and Rac-1 activation in these cells. © 2013 John Wiley & Sons A/S.

  4. Biomechanical remodeling of the microenvironment by stromal Caveolin-1 favors tumor invasion and metastasis

    PubMed Central

    Goetz, Jacky G.; Minguet, Susana; Navarro-Lérida, Inmaculada; Lazcano, Juan José; Samaniego, Rafael; Calvo, Enrique; Tello, Marta; Osteso-Ibáñez, Teresa; Pellinen, Teijo; Echarri, Asier; Cerezo, Ana; Klein-Szanto, Andres J.P.; Garcia, Ricardo; Keely, Patricia J.; Sánchez-Mateos, Paloma; Cukierman, Edna; Del Pozo, Miguel A.

    2011-01-01

    Summary Mechanotransduction, a key determinant of tissue homeostasis and tumor progression, is driven by intercellular adhesions, cell contractility and forces generated with the microenvironment, dependent on extracellular matrix composition, organization and compliance. Caveolin-1 (Cav1) favors cell elongation in 3D cultures and promotes Rho-and force-dependent contraction, matrix alignment and microenvironment stiffening through regulation of p190RhoGAP. In turn, microenvironment remodeling by Cav1-fibroblasts forces cell elongation. Cav1-deficient mice have disorganized stromal tissue architecture. Stroma associated with human carcinomas and melanoma metastases is enriched in Cav1-expressing carcinoma-associated fibroblasts (CAFs). Cav1 expression in breast CAFs correlates with low survival, and Cav1 depletion in CAFs decreases CAF contractility. Consistently, fibroblast expression of Cav1, through p190RhoGAP regulation, favors directional migration and invasiveness of carcinoma cells in vitro. In vivo, stromal Cav1 remodels peri- and intratumoral microenvironments to facilitate tumor invasion, correlating with increased metastatic potency. Thus, Cav1 modulates tissue responses through force-dependent architectural regulation of the microenvironment. PMID:21729786

  5. Dexrazoxane prevents the development of the impaired cardiac phenotype in caveolin-1-disrupted mice.

    PubMed

    Polanski, Anne-Katrin; Ebner, Annette; Ebner, Bernd; Hofmann, Anja; Steinbronn, Nadine; Brandt, Aljoscha; Forkmann, Mathias; Tausche, Anne-Kathrin; Morawietz, Henning; Strasser, Ruth H; Wunderlich, Carsten

    2013-06-01

    : Caveolin-1-deficient (cav1) mice display a severely diseased cardiac phenotype with systolic and diastolic heart failure. Accumulating evidence supports a causative role of uncoupled endothelial nitric oxide synthase in the development of these abnormalities. Interestingly, a similar molecular mechanism was proposed for anthracycline-induced cardiomyopathy. Currently, dexrazoxane is approved for the prevention of anthracycline-induced cardiomyopathy. Given the molecular similarities between the anthracycline-induced cardiomyopathy and the cardiomyopathy in cav1 mice, we questioned whether dexrazoxane may also prevent the evolution of the cardiac pathologies in cav1 mice. We evaluated dexrazoxane treatment for 6 weeks in cav1 mice and wild-type controls. This study provides the first evidence for a reduced reactive oxygen species formation in the vessels of dexrazoxane-treated cav1 mice. This reduced oxidative stress resulted in a markedly reduced rate of apoptosis, which finally was translated into a significantly improved heart function in dexrazoxane-treated cav1 mice. These hemodynamic improvements were accompanied by significantly lowered proatrial natriuretic peptide levels. Notably, these protective properties of dexrazoxane were not evident in wild-type animals. Taken together, these novel findings indicate that dexrazoxane significantly reduces vascular reactive oxygen species formation cav1. Because this is paralleled by an improved cardiac performance in cav1 mice, our data suggest dexrazoxane as a novel therapeutic strategy in this specific cardiomyopathy.

  6. Paired hormone response elements predict caveolin-1 as a glucocorticoid target gene.

    PubMed

    van Batenburg, Marinus F; Li, Hualing; Polman, J Annelies; Lachize, Servane; Datson, Nicole A; Bussemaker, Harmen J; Meijer, Onno C

    2010-01-21

    Glucocorticoids act in part via glucocorticoid receptor binding to hormone response elements (HREs), but their direct target genes in vivo are still largely unknown. We developed the criterion that genomic occurrence of paired HREs at an inter-HRE distance less than 200 bp predicts hormone responsiveness, based on synergy of multiple HREs, and HRE information from known target genes. This criterion predicts a substantial number of novel responsive genes, when applied to genomic regions 10 kb upstream of genes. Multiple-tissue in situ hybridization showed that mRNA expression of 6 out of 10 selected genes was induced in a tissue-specific manner in mice treated with a single dose of corticosterone, with the spleen being the most responsive organ. Caveolin-1 was strongly responsive in several organs, and the HRE pair in its upstream region showed increased occupancy by glucocorticoid receptor in response to corticosterone. Our approach allowed for discovery of novel tissue specific glucocorticoid target genes, which may exemplify responses underlying the permissive actions of glucocorticoids.

  7. Regulation of caveolin-1 membrane trafficking by the Na/K-ATPase

    PubMed Central

    Cai, Ting; Wang, Haojie; Chen, Yiliang; Liu, Lijun; Gunning, William T; Quintas, Luis Eduardo M.; Xie, Zi-Jian

    2008-01-01

    Here, we show that the Na/K-ATPase interacts with caveolin-1 (Cav1) and regulates Cav1 trafficking. Graded knockdown of Na/K-ATPase decreases the plasma membrane pool of Cav1, which results in a significant reduction in the number of caveolae on the cell surface. These effects are independent of the pumping function of Na/K-ATPase, and instead depend on interaction between Na/K-ATPase and Cav1 mediated by an N-terminal caveolin-binding motif within the ATPase α1 subunit. Moreover, knockdown of the Na/K-ATPase increases basal levels of active Src and stimulates endocytosis of Cav1 from the plasma membrane. Microtubule-dependent long-range directional trafficking in Na/K-ATPase–depleted cells results in perinuclear accumulation of Cav1-positive vesicles. Finally, Na/K-ATPase knockdown has no effect on processing or exit of Cav1 from the Golgi. Thus, the Na/K-ATPase regulates Cav1 endocytic trafficking and stabilizes the Cav1 plasma membrane pool. PMID:18794328

  8. ROR1 sustains caveolae and survival signalling as a scaffold of cavin-1 and caveolin-1

    PubMed Central

    Yamaguchi, Tomoya; Lu, Can; Ida, Lisa; Yanagisawa, Kiyoshi; Usukura, Jiro; Cheng, Jinglei; Hotta, Naoe; Shimada, Yukako; Isomura, Hisanori; Suzuki, Motoshi; Fujimoto, Toyoshi; Takahashi, Takashi

    2016-01-01

    The receptor tyrosine kinase-like orphan receptor 1 (ROR1) sustains prosurvival signalling directly downstream of the lineage-survival oncogene NKX2-1/TTF-1 in lung adenocarcinoma. Here we report an unanticipated function of this receptor tyrosine kinase (RTK) as a scaffold of cavin-1 and caveolin-1 (CAV1), two essential structural components of caveolae. This kinase-independent function of ROR1 facilitates the interactions of cavin-1 and CAV1 at the plasma membrane, thereby preventing the lysosomal degradation of CAV1. Caveolae structures and prosurvival signalling towards AKT through multiple RTKs are consequently sustained. These findings provide mechanistic insight into how ROR1 inhibition can overcome EGFR–tyrosine kinase inhibitor (TKI) resistance due to bypass signalling via diverse RTKs such as MET and IGF-IR, which is currently a major clinical obstacle. Considering its onco-embryonic expression, inhibition of the scaffold function of ROR1 in patients with lung adenocarcinoma is an attractive approach for improved treatment of this devastating cancer. PMID:26725982

  9. Lower Serum Caveolin-1 Is Associated with Cerebral Microbleeds in Patients with Acute Ischemic Stroke

    PubMed Central

    Zhang, Jun; Zhu, Wusheng; Xiao, Lulu; Cao, Qinqin; Zhang, Hao; Wang, Huaiming; Ye, Zusen; Hao, Yonggang; Dai, Qiliang; Sun, Wen; Liu, Xinfeng; Ye, Ruidong

    2016-01-01

    Caveolin-1 (Cav-1) plays pivotal roles in the endothelial damage following stroke. The present study aimed to investigate whether serum Cav-1 level is associated with the presence of cerebral small vessel disease (cSVD) in patients with acute ischemic stroke. To this end, 156 patients were consecutively enrolled. Cranial magnetic resonance imaging was analyzed to determine the surrogates of cSVD, including cerebral microbleeds (CMBs), silent lacunar infarcts (SLIs), and white matter hyperintensities (WMHs). After adjusting for potential confounders, patients with low Cav-1 level had a higher risk of CMBs than patients with high Cav-1 level (OR: 4.05, 95% CI: 1.77–9.30). However, there was no relationship between Cav-1 and the presence of SLIs or WMHs. When CMBs were stratified by location and number, a similar association was found in patients with deep or infratentorial CMBs (OR: 4.04, 95% CI: 1.59–10.25) and with multiple CMBs (OR: 3.18, 95% CI: 1.16–8.72). These results suggest lower serum Cav-1 levels may be associated with CMBs, especially those that are multiple and located in deep brain or infratentorial structures, in patients with acute ischemic stroke. Cav-1 may be involved in the pathophysiology of CMBs, and may act as a potential target for treating cSVD. PMID:27119011

  10. Significance of caveolin-1 and matrix metalloproteinase 14 gene expression in canine mammary tumours.

    PubMed

    Ebisawa, M; Iwano, H; Nishikawa, M; Tochigi, Y; Komatsu, T; Endou, Y; Hirayama, K; Taniyama, H; Kadosawa, T; Yokota, H

    2015-11-01

    Canine mammary tumours (CMTs) are the most common neoplasms affecting female dogs. There is an urgent need for molecular biomarkers that can detect early stages of the disease in order to improve accuracy of CMT diagnosis. The aim of this study was to examine whether caveolin-1 (Cav-1) and matrix metalloproteinase 14 (MMP14) are associated with CMT histological malignancy and invasion. Sixty-five benign and malignant CMT samples and six normal canine mammary glands were analysed using quantitative reverse transcription-polymerase chain reaction. Cav-1 and MMP14 genes were highly expressed in CMT tissues compared to normal tissues. Cav-1 especially was overexpressed in malignant and invasive CMT tissues. When a CMT cell line was cultured on fluorescent gelatin-coated coverslips, localisation of Cav-1 was observed at invadopodia-mediated degradation sites of the gelatin matrix. These findings suggest that Cav-1 may be involved in CMT invasion and that the markers may be useful for estimating CMT malignancy.

  11. Caveolin-1 Expression Level in Cancer Associated Fibroblasts Predicts Outcome in Gastric Cancer

    PubMed Central

    Gao, Jun; Fan, Lifang; Li, Zonghuan; Yang, Guifang; Chen, Honglei

    2013-01-01

    Aims Altered expression of epithelial or stromal caveolin-1 (Cav-1) is observed in various types of human cancers. However, the clinical significance of Cav-1 expression in gastric cancer (GC) remains largely unknown. The present study aims to explore the clinicopathological significance and prognostic value of both tumor cells and cancer associated fibroblasts (CAFs) Cav-1 in GC. Methods and Results Quantum dots immunofluorescence histochemistry was performed to examine the expression of Cav-1 in 20 cases of gastritis without intestinal metaplasia (IM), 20 cases of gastritis with IM and 286 cases of GC. Positive rates of epithelial Cav-1 in gastritis without IM, gastritis with IM and GC showed a decreasing trend (P = 0.012). Low expression of Cav-1 in CAFs but not in tumor cells was an independent predictor of poor prognosis in GC patients (P = 0.034 and 0.005 respectively in disease free survival and overall survival). Cav-1 level in tumor cells and CAFs showed no significant correlation with classic clinicopathological features. Conclusions Loss of epithelial Cav-1 may promote malignant progression and low CAFs Cav-1 level herald worse outcome of GC patient, suggesting CAFs Cav-1 may be a candidate therapeutic target and a useful prognostic marker of GC. PMID:23527097

  12. Caveolin-1–dependent apoptosis induced by fibrin degradation products

    PubMed Central

    Guo, Yi-He; Hernandez, Irene; Isermann, Berend; Kang, Tae-bong; Medved, Leonid; Sood, Rashmi; Kerschen, Edward J.; Holyst, Trudy; Mosesson, Michael W.

    2009-01-01

    In mice lacking the blood coagulation regulator thrombomodulin, fibrinolytic degradation products (FDP) of fibrin induce apoptotic cell death of a specialized cell type in the placenta, polyploid trophoblast giant cells. Here, we document that this bioactivity of FDP is conserved in human FDP, is not limited to trophoblast cells, and is associated with an Aα-chain segment of fibrin fragment E (FnE). The majority of proapoptotic activity is arginine-glycine-aspartic acid (RGD)-independent and requires caveolin-1–dependent cellular internalization of FnE. Internalization through caveoli is mediated by an epitope contained within Aα52-81 that is necessary and sufficient for cellular uptake of FnE. Aα52-81 does not cause apoptosis itself, and competitively inhibits FnE internalization and apoptosis induction. Apoptotic activity per se resides within Aα17-37 and requires the N-terminal neoepitope generated by release of fibrinopeptide A. Cellular internalization of FnE elicits depression of mitochondrial function and consequent apoptosis that is strictly dependent on the activity of caspases 9 and 3. These findings describe the molecular details of a novel mechanism linking fibrin degradation to cell death in the placenta, which may also contribute to pathologic alterations in nonplacental vascular beds that are associated with fibrinolysis. PMID:19074731

  13. E-cadherin determines Caveolin-1 tumor suppression or metastasis enhancing function in melanoma cells

    PubMed Central

    Lobos-González, L; Aguilar, L; Diaz, J; Diaz, N; Urra, H; Torres, V; Silva, V; Fitzpatrick, C; Lladser, A; Hoek, K.S.; Leyton, L; Quest, AFG

    2013-01-01

    SUMMARY The role of caveolin-1 (CAV1) in cancer is highly controversial. CAV1 suppresses genes that favor tumor development, yet also promotes focal adhesion turnover and migration of metastatic cells. How these contrasting observations relate to CAV1 function in vivo is unclear. Our previous studies implicate E-cadherin in CAV1-dependent tumor suppression. Here we use murine melanoma B16F10 cells, with low levels of endogenous CAV1 and E-cadherin, to unravel how CAV1 affects tumor growth and metastasis, and to assess how co-expression of E-cadherin modulates CAV1 function in vivo in C57BL/6 mice. We find that overexpression of CAV1 in B16F10(cav-1) cells reduces subcutaneous tumor formation, but enhances metastasis relative to control cells. Furthermore, E-cadherin expression in B16F10(E-cad) cells reduces subcutaneous tumor formation, and lung metastasis when intravenously injected. Importantly, co-expression of CAV1 and E-cadherin in B16F10(cav1/E-cad) cells abolishes tumor formation, lung metastasis, increased Rac-1 activity and cell migration observed with B16F10(cav-1) cells. Finally, consistent with the notion that CAV1 participates in switching human melanomas to a more malignant phenotype, elevated levels of CAV1 expression correlated with enhanced migration and Rac-1 activation in these cells. PMID:23470013

  14. Loss of Caveolin-1 Impairs Retinal Function Due to Disturbance of Subretinal Microenvironment*

    PubMed Central

    Li, Xiaoman; McClellan, Mark E.; Tanito, Masaki; Garteiser, Philippe; Towner, Rheal; Bissig, David; Berkowitz, Bruce A.; Fliesler, Steven J.; Woodruff, Michael L.; Fain, Gordon L.; Birch, David G.; Khan, M. Suhaib; Ash, John D.; Elliott, Michael H.

    2012-01-01

    Caveolin-1 (Cav-1), an integral component of caveolar membrane domains, is expressed in several retinal cell types, including photoreceptors, retinal vascular endothelial cells, Müller glia, and retinal pigment epithelium (RPE) cells. Recent evidence links Cav-1 to ocular diseases, including autoimmune uveitis, diabetic retinopathy, and primary open angle glaucoma, but its role in normal vision is largely undetermined. In this report, we show that ablation of Cav-1 results in reduced inner and outer retinal function as measured, in vivo, by electroretinography and manganese-enhanced MRI. Somewhat surprisingly, dark current and light sensitivity were normal in individual rods (recorded with suction electrode methods) from Cav-1 knock-out (KO) mice. Although photoreceptor function was largely normal, in vitro, the apparent K+ affinity of the RPE-expressed α1-Na+/K+-ATPase was decreased in Cav-1 KO mice. Cav-1 KO retinas also displayed unusually tight adhesion with the RPE, which could be resolved by brief treatment with hyperosmotic medium, suggesting alterations in outer retinal fluid homeostasis. Collectively, these findings demonstrate that reduced retinal function resulting from Cav-1 ablation is not photoreceptor-intrinsic but rather involves impaired subretinal and/or RPE ion/fluid homeostasis. PMID:22451674

  15. Caveolin-1 regulates chemokine receptor 5-mediated contribution of bone marrow-derived cells to dermal fibrosis

    PubMed Central

    Lee, Rebecca; Perry, Beth; Heywood, Jonathan; Reese, Charles; Bonner, Michael; Hatfield, Corey M.; Silver, Richard M.; Visconti, Richard P.; Hoffman, Stanley; Tourkina, Elena

    2014-01-01

    In fibrotic diseases caveolin-1 underexpression in fibroblasts results in collagen overexpression and in monocytes leads to hypermigration. These profibrotic behaviors are blocked by the caveolin-1 scaffolding domain peptide (CSD) which compensates for caveolin-1 deficiency. Monocytes and fibroblasts are related in that monocytes are the progenitors of fibrocytes (CD45+/Collagen I+ cells) that, in turn, are the progenitors of many fibroblasts in fibrotic tissues. In an additional anti-fibrotic activity, CSD blocks monocyte differentiation into fibrocytes. We studied a mouse fibrosis model (Pump Model) involving systemic bleomycin delivery that closely models scleroderma (SSc) in several ways, the most important of which for this study is that fibrosis is observed in the lungs, skin, and internal organs. We show here that dermal thickness is increased 2-fold in the Pump Model and that this effect is almost completely blocked by CSD (p < 0.001). Concomitantly, the subcutaneous fat layer becomes >80% thinner. This effect is also blocked by CSD (p < 0.001). Even in mice receiving vehicle instead of bleomycin, CSD increases the thickness of the fat layer. To study the mechanisms of action of bleomycin and CSD, we examined the accumulation of the chemokine receptor CCR5 and its ligands MIP1α and MIP1β in fibrotic tissue and their roles in monocyte migration. Fibrocytes and other leukocytes expressing CCR5 and its ligands were present at high levels in the fibrotic dermis of SSc patients and Pump Model mice while CSD blocked their accumulation in mouse dermis. Migration toward CCR5 ligands of SSc monocytes and Pump Model bone marrow cells was 3-fold greater than cells from control subjects. This enhanced migration was almost completely blocked by CSD. These results suggest that low monocyte caveolin-1 promotes fibrosis by enhancing the recruitment of fibrocytes and their progenitors into affected tissue. PMID:24966836

  16. Reversal of maladaptive fibrosis and compromised ventricular function in the pressure overloaded heart by a caveolin-1 surrogate peptide.

    PubMed

    Pleasant-Jenkins, Dorea; Reese, Charles; Chinnakkannu, Panneerselvem; Kasiganesan, Harinath; Tourkina, Elena; Hoffman, Stanley; Kuppuswamy, Dhandapani

    2017-04-01

    Chronic ventricular pressure overload (PO) results in congestive heart failure (CHF) in which myocardial fibrosis develops in concert with ventricular dysfunction. Caveolin-1 is important in fibrosis in various tissues due to its decreased expression in fibroblasts and monocytes. The profibrotic effects of low caveolin-1 can be blocked with the caveolin-1 scaffolding domain peptide (CSD, a caveolin-1 surrogate) using both mouse models and human cells. We have studied the beneficial effects of CSD on mice in which PO was induced by trans-aortic constriction (TAC). Beneficial effects observed in TAC mice receiving CSD injections daily included: improved ventricular function (increased ejection fraction, stroke volume, and cardiac output; reduced wall thickness); decreased collagen I, collagen chaperone HSP47, fibronectin, and CTGF levels; decreased activation of non-receptor tyrosine kinases Pyk2 and Src; and decreased activation of eNOS. To determine the source of cells that contribute to fibrosis in CHF, flow cytometric studies were performed that suggested that myofibroblasts in the heart are in large part bone marrow-derived. Two CD45+ cell populations were observed. One (Zone 1) contained CD45+/HSP47-/macrophage marker+ cells (macrophages). The second (Zone 2) contained CD45(moderate)/HSP47+/macrophage marker- cells often defined as fibrocytes. TAC increased the number of cells in Zones 1 and 2 and the level of HSP47 in Zone 2. These studies are a first step in elucidating the mechanism of action of CSD in heart fibrosis and promoting the development of CSD as a novel treatment to reduce fibrosis and improve ventricular function in CHF patients.

  17. Modification of an apparatus for tumor-suppressor protein crystal growth in the International Space Station

    NASA Astrophysics Data System (ADS)

    de Morais Mendonca Teles, Antonio

    Some human diseases as tumors are being studied continuously for the development of vaccines against them. And a way of doing that is by means of proteins research. There are some kinds of proteins, like the p53 and p73 proteins, which are tumor suppressors. There are other diseases such as A.I.D.S., hansenosis, the Parkinson's and Chagas' diseases which are protein-related. The determination of how proteins geometrically order themselves, during its biological functions is very necessary to understand how a protein's structure affects its function, to design vaccines that intercede in tumor-protein activities and in other proteins related to those other diseases. The protein crystal growth in microgravity environment produces purer crystallization than on the ground, and it is a powerful tool to produce better vaccines. Several data have already been acquired using ground-based research and in spaceflight experiments aboard the Spacelab and Space Shuttle missions, and in the MIR and in the International Space Station (ISS). Here in this paper, I propose to be performed in the ISS Biological Research Facility (which is being developed), multiple crystal growth of proteins related to cancer (as tumors suppressors and oncoproteins), A.I.D.S., hansenosis, the Parkinson's and Chagas' diseases, for the future obtaining of possible vaccines against them. I also propose a simple and practical equipment, a modification of the crystallization plates (which use a vapor diffusion technique) inside each cylinder of the Protein Crystallization Apparatus in Microgravity (PCAM), with multiple chambers with different sizes. Instead of using some chambers with the same size it is better to use several chambers with different sizes. Why is that? The answer is: the energy associated with the surface tension of the liquid in the chamber is directly related to the circle area of it. So, to minimize the total energy of the surface tension of a proteins liquid -making it more stable

  18. The von Hippel-Lindau tumor suppressor stabilizes novel plant homeodomain protein Jade-1.

    PubMed

    Zhou, Mina I; Wang, Hongmei; Ross, Jonathan J; Kuzmin, Igor; Xu, Chengen; Cohen, Herbert T

    2002-10-18

    The von Hippel-Lindau disease gene (VHL) is the causative gene for most adult renal cancers. However, the mechanism by which VHL protein functions as a renal tumor suppressor remains largely unknown. To identify low occupancy VHL protein partners with potential relevance to renal cancer, we screened a human kidney library against human VHL p30 using a yeast two-hybrid approach. Jade-1 (gene for Apoptosis and Differentiation in Epithelia) encodes a previously uncharacterized 64-kDa protein that interacts strongly with VHL protein and is most highly expressed in kidney. Jade-1 protein is short-lived and contains a candidate destabilizing (PEST) motif and plant homeodomains that are not required for the VHL interaction. Jade-1 is abundant in proximal tubule cells, which are clear-cell renal cancer precursors, and expression increases with differentiation. Jade-1 is expressed in cytoplasm and the nucleus diffusely and in speckles, where it partly colocalizes with VHL. VHL reintroduction into renal cancer cells increases endogenous Jade-1 protein abundance up to 10-fold. Furthermore, VHL increases Jade-1 protein half-life up to 3-fold. Thus, direct protein stabilization is identified as a new VHL function. Moreover, Jade-1 protein represents a novel candidate regulatory factor in VHL-mediated renal tumor suppression.

  19. Static pressure drives proliferation of vascular smooth muscle cells via caveolin-1/ERK1/2 pathway

    SciTech Connect

    Luo, Di-xian; Cheng, Jiming; Xiong, Yan; Li, Junmo; Xia, Chenglai; Xu, Canxin; Wang, Chun; Zhu, Bingyang; Hu, Zhuowei; Liao, Duan-fang

    2010-01-22

    Intimal hyperplasia plays an important role in various types of vascular remodeling. Mechanical forces derived from blood flow are associated with the proliferation of vascular smooth muscle cells (VSMC). This contributes to many vascular disorders such as hypertension, atherosclerosis and restenosis after percutaneous transluminal angioplasty (PTA). In this study, we show that static pressure induces the proliferation of VSMC and activates its related signal pathway. VSMC from a rat aorta were treated with different pressures (0, 60, 90, 120, 150 and 180 mm Hg) in a custom-made pressure incubator for 24 h. The most active proliferation of VSMC was detected at a pressure of 120 mm Hg. VSMC was also incubated under a static pressure of 120 mm Hg for different time intervals (0, 2, 4, 8, 12 and 24 h). We found that static pressure significantly stimulates VSMC proliferation. Extracellular signal-regulated kinases 1/2 (ERK1/2) activation showed a peak at the pressure of 120 mm Hg at 4-h time point. Moreover, caveolin-1 expression was significantly inhibited by rising static pressure. Downregulation of VSMC proliferation could be found after PD98059 (ERK1/2 phosphorylation inhibitor) treatment. Our data also showed that a siRNA-mediated caveolin-1 knock down increased ERK1/2 phosphorylation and VSMC proliferation. These results demonstrate that static pressure promotes VSMC proliferation via the Caveolin-1/ERK1/2 pathway.

  20. Negative regulation of EGFR signalling by the human folliculin tumour suppressor protein

    PubMed Central

    Laviolette, Laura A.; Mermoud, Julien; Calvo, Isabel A.; Olson, Nicholas; Boukhali, Myriam; Steinlein, Ortrud K.; Roider, Elisabeth; Sattler, Elke C.; Huang, Dachuan; Teh, Bin Tean; Motamedi, Mo; Haas, Wilhelm; Iliopoulos, Othon

    2017-01-01

    Germline mutations in the Folliculin (FLCN) tumour suppressor gene result in fibrofolliculomas, lung cysts and renal cancers, but the precise mechanisms of tumour suppression by FLCN remain elusive. Here we identify Rab7A, a small GTPase important for endocytic trafficking, as a novel FLCN interacting protein and demonstrate that FLCN acts as a Rab7A GTPase-activating protein. FLCN−/− cells display slower trafficking of epidermal growth factor receptors (EGFR) from early to late endosomes and enhanced activation of EGFR signalling upon ligand stimulation. Reintroduction of wild-type FLCN, but not tumour-associated FLCN mutants, suppresses EGFR signalling in a Rab7A-dependent manner. EGFR signalling is elevated in FLCN−/− tumours and the EGFR inhibitor afatinib suppresses the growth of human FLCN−/− cells as tumour xenografts. The functional interaction between FLCN and Rab7A appears conserved across species. Our work highlights a mechanism explaining, at least in part, the tumour suppressor function of FLCN. PMID:28656962

  1. Purification and crystallization of the human EF-hand tumour suppressor protein S100A2

    SciTech Connect

    Koch, Michael; Diez, Joachim; Fritz, Günter

    2006-11-01

    Human recombinant tumour suppressor S100A2 and a mutant lacking cysteine residues have been purified and crystallized. Only the crystals of the mutant protein diffracted to appropriate resolution and a complete data set was recorded at 1.7 Å. S100A2 is a Ca{sup 2+}-binding EF-hand protein that is mainly localized in the nucleus. There, it acts as a tumour suppressor by binding and activating p53. Wild-type S100A2 and a S100A2 variant lacking cysteines have been purified. CD spectroscopy showed that there are no changes in secondary-structure composition. The S100A2 mutant was crystallized in a calcium-free form. The crystals, with dimensions 30 × 30 × 70 µm, diffract to 1.7 Å and belong to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 43.5, b = 57.8, c = 59.8 Å, α = β = γ = 90°. Preliminary analysis of the X-ray data indicates that there are two subunits per asymmetric unit.

  2. Purification of the NF2 tumor suppressor protein from human erythrocytes.

    PubMed

    Jindal, Hitesh K; Yoshinaga, Kazumi; Seo, Pil-Soo; Lutchman, Mohini; Dion, Patrick A; Rouleau, Guy A; Hanada, Toshihiko; Chishti, Athar H

    2006-11-01

    Neurofibromatosis type 2 (NF2) is an autosomal dominant disease predisposing individuals to the risk of developing tumors of cranial and spinal nerves. The NF2 tumor suppressor protein, known as Merlin/Schwanomin, is a member of the protein 4.1 superfamily that function as links between the cytoskeleton and the plasma membrane. Upon selective extraction of membrane-associated proteins from erythrocyte plasma membrane (ghosts) using low ionic strength solution, the bulk of NF2 protein remains associated with the spectrin-actin depleted inside-out-vesicles. Western blot analysis showed a approximately 70 kDa polypeptide in the erythrocyte plasma membrane. Furthermore, quantitative removal of NF2 protein from the inside-out-vesicles was achieved using 1.0 M potassium iodide, a treatment known to remove tightly-bound peripheral membrane proteins. These results suggest a novel mode of NF2 protein association with the erythrocyte membrane that is distinct from the known membrane interactions of protein 4.1. Based on these biochemical properties, several purification strategies were devised to isolate native NF2 protein from human erythrocyte ghosts. Using purified and recombinant NF2 protein as internal standards, we quantified approximately 41-65,000 molecules of NF2 protein per erythrocyte. We provide evidence for the presence of NF2 protein in the human erythrocyte membrane. The identification of NF2 protein in the human erythrocyte membrane will make it feasible to discover novel interactions of NF2 protein utilizing powerful techniques of erythrocyte biochemistry and genetics in mammalian cells.

  3. Isoform-specific interactions of the von Hippel-Lindau tumor suppressor protein

    PubMed Central

    Minervini, Giovanni; Mazzotta, Gabriella M.; Masiero, Alessandro; Sartori, Elena; Corrà, Samantha; Potenza, Emilio; Costa, Rodolfo; Tosatto, Silvio C. E.

    2015-01-01

    Deregulation of the von Hippel-Lindau tumor suppressor protein (pVHL) is considered one of the main causes for malignant renal clear-cell carcinoma (ccRCC) insurgence. In human, pVHL exists in two isoforms, pVHL19 and pVHL30 respectively, displaying comparable tumor suppressor abilities. Mutations of the p53 tumor suppressor gene have been also correlated with ccRCC insurgence and ineffectiveness of treatment. A recent proteomic analysis linked full length pVHL30 with p53 pathway regulation through complex formation with the p14ARF oncosuppressor. The alternatively spliced pVHL19, missing the first 53 residues, lacks this interaction and suggests an asymmetric function of the two pVHL isoforms. Here, we present an integrative bioinformatics and experimental characterization of the pVHL oncosuppressor isoforms. Predictions of the pVHL30 N-terminus three-dimensional structure suggest that it may exist as an ensemble of structured and disordered forms. The results were used to guide Yeast two hybrid experiments to highlight isoform-specific binding properties. We observed that the physical pVHL/p14ARF interaction is specifically mediated by the 53 residue long pVHL30 N-terminal region, suggesting that this N-terminus acts as a further pVHL interaction interface. Of note, we also observed that the shorter pVHL19 isoform shows an unexpected high tendency to form homodimers, suggesting an additional isoform-specific binding specialization. PMID:26211615

  4. The Enamovirus P0 protein is a silencing suppressor which inhibits local and systemic RNA silencing through AGO1 degradation

    SciTech Connect

    Fusaro, Adriana F.; Correa, Regis L.; Nakasugi, Kenlee; Jackson, Craig; Kawchuk, Lawrence; Vaslin, Maite F.S.; Waterhouse, Peter M.

    2012-05-10

    The P0 protein of poleroviruses and P1 protein of sobemoviruses suppress the plant's RNA silencing machinery. Here we identified a silencing suppressor protein (SSP), P0{sup PE}, in the Enamovirus Pea enation mosaic virus-1 (PEMV-1) and showed that it and the P0s of poleroviruses Potato leaf roll virus and Cereal yellow dwarf virus have strong local and systemic SSP activity, while the P1 of Sobemovirus Southern bean mosaic virus supresses systemic silencing. The nuclear localized P0{sup PE} has no discernable sequence conservation with known SSPs, but proved to be a strong suppressor of local silencing and a moderate suppressor of systemic silencing. Like the P0s from poleroviruses, P0{sup PE} destabilizes AGO1 and this action is mediated by an F-box-like domain. Therefore, despite the lack of any sequence similarity, the poleroviral and enamoviral SSPs have a conserved mode of action upon the RNA silencing machinery.

  5. Gastrokines: stomach-specific proteins with putative homeostatic and tumor suppressor roles.

    PubMed

    Menheniott, Trevelyan R; Kurklu, Bayzar; Giraud, Andrew S

    2013-01-15

    During the past decade, a new family of stomach-specific proteins has been recognized. Known as "gastrokines" (GKNs), these secreted proteins are products of gastric mucus-producing cell lineages. GKNs are highly conserved in physical structure, and emerging data point to convergent functions in the modulation of gastric mucosal homeostasis and inflammation. While GKNs are highly prevalent in the normal stomach, frequent loss of GKN expression in gastric cancers, coupled with established antiproliferative activity, suggests putative tumor suppressor roles. Conversely, ectopic expression of GKNs in reparative lesions of Crohn's disease alludes to additional activity in epithelial wound healing and/or repair. Modes of action remain unsolved, but the recent demonstration of a GKN2-trefoil factor 1 heterodimer implicates functional interplay with trefoil factors. This review aims to provide a historical account of GKN biology and encapsulate the rapidly accumulating evidence supporting roles in gastric epithelial homeostasis and tumor suppression.

  6. The tumour suppressor APC promotes HIV-1 assembly via interaction with Gag precursor protein

    PubMed Central

    Miyakawa, Kei; Nishi, Mayuko; Matsunaga, Satoko; Okayama, Akiko; Anraku, Masaki; Kudoh, Ayumi; Hirano, Hisashi; Kimura, Hirokazu; Morikawa, Yuko; Yamamoto, Naoki; Ono, Akira; Ryo, Akihide

    2017-01-01

    Diverse cellular proteins and RNAs are tightly regulated in their subcellular localization to exert their local function. Here we report that the tumour suppressor adenomatous polyposis coli protein (APC) directs the localization and assembly of human immunodeficiency virus (HIV)-1 Gag polyprotein at distinct membrane components to enable the efficient production and spread of infectious viral particles. A proteomic analysis and subsequent biomolecular interaction assay reveals that the carboxyl terminus of APC interacts with the matrix region of Gag. Ectopic expression of APC, but not its familial adenomatous polyposis-related truncation mutant, prominently enhances HIV-1 production. Conversely, the depletion of APC leads to a significant decrease in membrane targeting of viral components, resulting in the severe loss of production of infectious virions. Furthermore, APC promotes the directional assembly of viral components at virological synapses, thereby facilitating cell-to-cell viral transmission. These findings reveal an unexpected role of APC in the directional spread of HIV-1. PMID:28134256

  7. Analysis of chikungunya virus proteins reveals that non-structural proteins nsP2 and nsP3 exhibit RNA interference (RNAi) suppressor activity.

    PubMed

    Mathur, Kalika; Anand, Abhishek; Dubey, Sunil Kumar; Sanan-Mishra, Neeti; Bhatnagar, Raj K; Sunil, Sujatha

    2016-11-30

    RNAi pathway is an antiviral defence mechanism employed by insects that result in degradation of viral RNA thereby curbing infection. Several viruses including flaviviruses encode viral suppressors of RNAi (VSRs) to counteract the antiviral RNAi pathway. Till date, no VSR has been reported in alphaviruses. The present study was undertaken to evaluate chikungunya virus (CHIKV) proteins for RNAi suppressor activity. We systematically analyzed all nine CHIKV proteins for RNAi suppressor activity using Sf21 RNAi sensor cell line based assay. Two non-structural proteins, namely, nsP2 and nsP3 were found to exhibit RNAi suppressor activity. We further validated the findings in natural hosts, namely in Aedes and in mammalian cell lines and further through EMSA and Agrobacterium infiltration in GFP silenced transgenic tobacco plants. Domains responsible for maximum RNAi suppressor activity were also identified within these proteins. RNA binding motifs in these domains were identified and their participation in RNAi suppression evaluated using site directed mutagenesis. Sequence alignment of these motifs across all species of known alphaviruses revealed conservation of these motifs emphasizing on a similar role of action in other species of alphaviruses as well. Further validation of RNAi suppressor activity of these proteins awaits establishment of specific virus infection models.

  8. Analysis of chikungunya virus proteins reveals that non-structural proteins nsP2 and nsP3 exhibit RNA interference (RNAi) suppressor activity

    PubMed Central

    Mathur, Kalika; Anand, Abhishek; Dubey, Sunil Kumar; Sanan-Mishra, Neeti; Bhatnagar, Raj K.; Sunil, Sujatha

    2016-01-01

    RNAi pathway is an antiviral defence mechanism employed by insects that result in degradation of viral RNA thereby curbing infection. Several viruses including flaviviruses encode viral suppressors of RNAi (VSRs) to counteract the antiviral RNAi pathway. Till date, no VSR has been reported in alphaviruses. The present study was undertaken to evaluate chikungunya virus (CHIKV) proteins for RNAi suppressor activity. We systematically analyzed all nine CHIKV proteins for RNAi suppressor activity using Sf21 RNAi sensor cell line based assay. Two non-structural proteins, namely, nsP2 and nsP3 were found to exhibit RNAi suppressor activity. We further validated the findings in natural hosts, namely in Aedes and in mammalian cell lines and further through EMSA and Agrobacterium infiltration in GFP silenced transgenic tobacco plants. Domains responsible for maximum RNAi suppressor activity were also identified within these proteins. RNA binding motifs in these domains were identified and their participation in RNAi suppression evaluated using site directed mutagenesis. Sequence alignment of these motifs across all species of known alphaviruses revealed conservation of these motifs emphasizing on a similar role of action in other species of alphaviruses as well. Further validation of RNAi suppressor activity of these proteins awaits establishment of specific virus infection models. PMID:27901124

  9. Genetic variation in caveolin-1 correlates with long-term pancreas transplant function.

    PubMed

    Hamilton, A; Mittal, S; Barnardo, M C N M; Fuggle, S V; Friend, P; Gough, S C L; Simmonds, M J

    2015-05-01

    Pancreas transplantation is a successful treatment for a selected group of people with type 1 diabetes. Continued insulin production can decrease over time and identifying predictors of long-term graft function is key to improving survival. The aim of this study was to screen subjects for variation in the Caveolin-1 gene (Cav1), previously shown to correlate with long-term kidney transplant function. We genotyped 435 pancreas transplant donors and 431 recipients who had undergone pancreas transplantation at the Oxford Transplant Centre, UK, for all known common variation in Cav1. Death-censored cumulative events were analyzed using Kaplan-Meier and Cox regression. Unlike kidney transplantation, the rs4730751 variant in our pancreas donors or transplant recipients did not correlate with long-term graft function (p = 0.331-0.905). Presence of rs3801995 TT genotype (p = 0.009) and rs9920 CC/CT genotype (p = 0.010) in our donors did however correlate with reduced long-term graft survival. Multivariate Cox regression (adjusted for donor and recipient transplant factors) confirmed the association of rs3801995 (p = 0.009, HR = 1.83;[95% CI = 1.16-2.89]) and rs9920 (p = 0.037, HR = 1.63; [95% CI = 1.03-2.73]) with long-term graft function. This is the first study to provide evidence that donor Cav1 genotype correlates with long-term pancreas graft function. Screening Cav1 in other datasets is required to confirm these pilot results. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

  10. HIV inhibits endothelial reverse cholesterol transport through impacting subcellular Caveolin-1 trafficking.

    PubMed

    Lin, Shanshan; Nadeau, Peter E; Mergia, Ayalew

    2015-07-15

    Human immunodeficiency virus (HIV) infection leads to decreased reverse cholesterol transport (RCT) in macrophages, and Nef mediated down-regulation and redistribution of ATP-binding cassette transporter A1 (ABCA1) are identified as key factors for this effect. This may partially explain the increased risk of atherosclerosis in HIV infected individuals. Since endothelial dysfunction is key in the initial stages of atherosclerosis, we sought to determine whether RCT was affected in human aortic endothelial cells (HAECs). We found that apoA-I does not significantly stimulate cholesterol efflux in HAECs while cholesterol efflux to high-density lipoprotein (HDL) was dramatically reduced in HAECs co-cultured with HIV infected cells. Studies with wild type and Nef defective HIV revealed no significant differences suggesting that multiple factors are working perhaps in concert with Nef to affect cholesterol efflux to HDL from HAECs. Interestingly, treating HAECs with recombinant Nef showed similar effect in HDL mediated cholesterol efflux as observed in HAECs co-cultured with HIV infected cells. Using a detergent-free based subcellular fractionation approach, we demonstrated that exposure of HAECs to HIV infected cells or Nef alone disrupts caveolin 1 (Cav-1) subcellular trafficking upon HDL stimulation. Moreover, Nef significantly enhanced tyrosine 14 phosphorylation of Cav-1 which may have an impact on recycling of Cav-1 and caveolae. These results suggest that HIV interferes with cholesterol efflux by HDL in HAECs through the disruption of Cav-1s' cellular distribution and that multiple factors are involved, possibly including Nef, for the inhibition of HDL mediated cholesterol efflux and alteration of cellular distribution of Cav-1.

  11. Caveolin-1 and Altered Neuregulin Signaling Contribute to the Pathophysiological Progression of Diabetic Peripheral Neuropathy

    PubMed Central

    McGuire, James F.; Rouen, Shefali; Siegfreid, Eric; Wright, Douglas E.; Dobrowsky, Rick T.

    2009-01-01

    OBJECTIVE Evaluate if Erb B2 activation and the loss of caveolin-1 (Cav1) contribute to the pathophysiological progression of diabetic peripheral neuropathy (DPN). RESEARCH DESIGN AND METHODS Cav1 knockout and wild-type C57BL/6 mice were rendered diabetic with streptozotocin, and changes in motor nerve conduction velocity (MNCV), mechanical and thermal hypoalgesia, Erb B2 phosphorylation (pErb B2), and epidermal nerve fiber density were assessed. The contribution of Erb B2 to DPN was assessed using the Erb B2 inhibitors PKI 166 and erlotinib and a conditional bitransgenic mouse that expressed a constitutively active form of Erb B2 in myelinated Schwann cells (SCs). RESULTS Diabetic mice exhibited decreased MNCV and mechanical and thermal sensitivity, but the extent of these deficits was more severe in diabetic Cav1 knockout mice. Diabetes increased pErb B2 levels in both genotypes, but the absence of Cav1 correlated with a greater increase in pErb B2. Erb B2 activation contributed to the mechanical hypoalgesia and MNCV deficits in both diabetic genotypes because treatment with erlotinib or PKI 166 improved these indexes of DPN. Similarly, induction of a constitutively active Erb B2 in myelinated SCs was sufficient to decrease MNCV and induce a mechanical hypoalgesia in the absence of diabetes. CONCLUSIONS Increased Erb B2 activity contributes to specific indexes of DPN, and Cav1 may be an endogenous regulator of Erb B2 signaling. Altered Erb B2 signaling is a novel mechanism that contributes to SC dysfunction in diabetes, and inhibiting Erb B2 may ameliorate deficits of tactile sensitivity in DPN. PMID:19675140

  12. Caveolin-1 and altered neuregulin signaling contribute to the pathophysiological progression of diabetic peripheral neuropathy.

    PubMed

    McGuire, James F; Rouen, Shefali; Siegfreid, Eric; Wright, Douglas E; Dobrowsky, Rick T

    2009-11-01

    Evaluate if Erb B2 activation and the loss of caveolin-1 (Cav1) contribute to the pathophysiological progression of diabetic peripheral neuropathy (DPN). Cav1 knockout and wild-type C57BL/6 mice were rendered diabetic with streptozotocin, and changes in motor nerve conduction velocity (MNCV), mechanical and thermal hypoalgesia, Erb B2 phosphorylation (pErb B2), and epidermal nerve fiber density were assessed. The contribution of Erb B2 to DPN was assessed using the Erb B2 inhibitors PKI 166 and erlotinib and a conditional bitransgenic mouse that expressed a constitutively active form of Erb B2 in myelinated Schwann cells (SCs). Diabetic mice exhibited decreased MNCV and mechanical and thermal sensitivity, but the extent of these deficits was more severe in diabetic Cav1 knockout mice. Diabetes increased pErb B2 levels in both genotypes, but the absence of Cav1 correlated with a greater increase in pErb B2. Erb B2 activation contributed to the mechanical hypoalgesia and MNCV deficits in both diabetic genotypes because treatment with erlotinib or PKI 166 improved these indexes of DPN. Similarly, induction of a constitutively active Erb B2 in myelinated SCs was sufficient to decrease MNCV and induce a mechanical hypoalgesia in the absence of diabetes. Increased Erb B2 activity contributes to specific indexes of DPN, and Cav1 may be an endogenous regulator of Erb B2 signaling. Altered Erb B2 signaling is a novel mechanism that contributes to SC dysfunction in diabetes, and inhibiting Erb B2 may ameliorate deficits of tactile sensitivity in DPN.

  13. Src-dependent phosphorylation of caveolin-1 Tyr-14 promotes swelling and release of caveolae

    PubMed Central

    Zimnicka, Adriana M.; Husain, Yawer S.; Shajahan, Ayesha N.; Sverdlov, Maria; Chaga, Oleg; Chen, Zhenlong; Toth, Peter T.; Klomp, Jennifer; Karginov, Andrei V.; Tiruppathi, Chinnaswamy; Malik, Asrar B.; Minshall, Richard D.

    2016-01-01

    Caveolin 1 (Cav1) is a required structural component of caveolae, and its phosphorylation by Src is associated with an increase in caveolae-mediated endocytosis. Here we demonstrate, using quantitative live-cell 4D, TIRF, and FRET imaging, that endocytosis and trafficking of caveolae are associated with a Cav1 Tyr-14 phosphorylation-dependent conformational change, which spatially separates, or loosens, Cav1 molecules within the oligomeric caveolar coat. When tracked by TIRF and spinning-disk microscopy, cells expressing phosphomimicking Cav1 (Y14D) mutant formed vesicles that were greater in number and volume than with Y14F-Cav1-GFP. Furthermore, we observed in HEK cells cotransfected with wild-type, Y14D, or Y14F Cav1-CFP and -YFP constructs that FRET efficiency was greater with Y14F pairs than with Y14D, indicating that pY14-Cav1 regulates the spatial organization of Cav1 molecules within the oligomer. In addition, albumin-induced Src activation or direct activation of Src using a rapamycin-inducible Src construct (RapR-Src) led to an increase in monomeric Cav1 in Western blots, as well as a simultaneous increase in vesicle number and decrease in FRET intensity, indicative of a Src-mediated conformational change in CFP/YFP-tagged WT-Cav1 pairs. We conclude that phosphorylation of Cav1 leads to separation or “spreading” of neighboring negatively charged N-terminal phosphotyrosine residues, promoting swelling of caveolae, followed by their release from the plasma membrane. PMID:27170175

  14. Lipopolysaccharide-induced caveolin-1 phosphorylation-dependent increase in transcellular permeability precedes the increase in paracellular permeability.

    PubMed

    Wang, Nan; Zhang, Dan; Sun, Gengyun; Zhang, Hong; You, Qinghai; Shao, Min; Yue, Yang

    2015-01-01

    Lipopolysaccharide (LPS) was shown to induce an increase in caveolin-1 (Cav-1) expression in endothelial cells; however, the mechanisms regarding this response and the consequences on caveolae-mediated transcellular transport have not been completely investigated. This study aims to investigate the role of LPS-induced Cav-1 phosphorylation in pulmonary microvascular permeability in pulmonary microvascular endothelial cells (PMVECs). Rat PMVECs were isolated, cultured, and identified. Endocytosis experiments were employed to stain the nuclei by DAPI, and images were obtained with a fluorescence microscope. Permeability of endothelial cultures was measured to analyze the barrier function of endothelial monolayer. Western blot assay was used to examine the expression of Cav-1, pCav-1, triton-insoluble Cav-1, and triton-soluble Cav-1 protein. The LPS treatment induced phosphorylation of Cav-1, but did not alter the total Cav-1 level till 60 min in both rat and human PMVECs. LPS treatment also increased the triton-insoluble Cav-1 level, which peaked 15 min after LPS treatment in both rat and human PMVECs. LPS treatment increases the intercellular cell adhesion molecule-1 expression. Src inhibitors, including PP2, PP1, Saracatinib, and Quercetin, partially inhibited LPS-induced phosphorylation of Cav-1. In addition, both PP2 and caveolae disruptor MβCD inhibited LPS-induced increase of triton-insoluble Cav-1. LPS induces permeability by activating interleukin-8 and vascular endothelial growth factor and targeting other adhesion markers, such as ZO-1 and occludin. LPS treatment also significantly increased the endocytosis of albumin, which could be blocked by PP2 or MβCD. Furthermore, LPS treatment for 15 min significantly elevated Evans Blue-labeled BSA transport in advance of a decrease in transendothelial electrical resistance of PMVEC monolayer at this time point. After LPS treatment for 30 min, transendothelial electrical resistance decreased significantly

  15. Activation of Akt by Advanced Glycation End Products (AGEs): Involvement of IGF-1 Receptor and Caveolin-1

    PubMed Central

    Yang, Su-Jung; Chen, Chen-Yu; Chang, Geen-Dong; Wen, Hui-Chin; Chen, Ching-Yu; Chang, Shi-Chuan; Liao, Jyh-Fei; Chang, Chung-Ho

    2013-01-01

    Diabetes is characterized by chronic hyperglycemia, which in turn facilitates the formation of advanced glycation end products (AGEs). AGEs activate signaling proteins such as Src, Akt and ERK1/2. However, the mechanisms by which AGEs activate these kinases remain unclear. We examined the effect of AGEs on Akt activation in 3T3-L1 preadipocytes. Addition of AGEs to 3T3-L1 cells activated Akt in a dose- and time-dependent manner. The AGEs-stimulated Akt activation was blocked by a PI3-kinase inhibitor LY 294002, Src inhibitor PP2, an antioxidant NAC, superoxide scavenger Tiron, or nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase inhibitor DPI, suggesting the involvement of Src and NAD(P)H oxidase in the activation of PI3-kinase-Akt pathway by AGEs. AGEs-stimulated Src tyrosine phosphorylation was inhibited by NAC, suggesting that Src is downstream of NAD(P)H oxidase. The AGEs-stimulated Akt activity was sensitive to Insulin-like growth factor 1 receptor (IGF-1R) kinase inhibitor AG1024. Furthermore, AGEs induced phosphorylation of IGF-1 receptorβsubunit (IGF-1Rβ) on Tyr1135/1136, which was sensitive to PP2, indicating that AGEs stimulate Akt activity by transactivating IGF-1 receptor. In addition, the AGEs-stimulated Akt activation was attenuated by β-methylcyclodextrin that abolishes the structure of caveolae, and by lowering caveolin-1 (Cav-1) levels with siRNAs. Furthermore, addition of AGEs enhanced the interaction of phospho-Cav-1 with IGF-1Rβ and transfection of 3T3-L1 cells with Cav-1 Y14F mutants inhibited the activation of Akt by AGEs. These results suggest that AGEs activate NAD(P)H oxidase and Src which in turn phosphorylates IGF-1 receptor and Cav-1 leading to activation of IGF-1 receptor and the downstream Akt in 3T3-L1 cells. AGEs treatment promoted the differentiation of 3T3-L1 preadipocytes and addition of AG1024, LY 294002 or Akt inhibitor attenuated the promoting effect of AGEs on adipogenesis, suggesting that IGF-1 receptor, PI3

  16. Long Non-coding RNA, PANDA, Contributes to the Stabilization of p53 Tumor Suppressor Protein.

    PubMed

    Kotake, Yojiro; Kitagawa, Kyoko; Ohhata, Tatsuya; Sakai, Satoshi; Uchida, Chiharu; Niida, Hiroyuki; Naemura, Madoka; Kitagawa, Masatoshi

    2016-04-01

    P21-associated noncoding RNA DNA damage-activated (PANDA) is induced in response to DNA damage and represses apoptosis by inhibiting the function of nuclear transcription factor Y subunit alpha (NF-YA) transcription factor. Herein, we report that PANDA affects regulation of p53 tumor-suppressor protein. U2OS cells were transfected with PANDA siRNAs. At 72 h post-transfection, cells were subjected to immunoblotting and quantitative reverse transcription-polymerase chain reaction. Depletion of PANDA was associated with decreased levels of p53 protein, but not p53 mRNA. The stability of p53 protein was markedly reduced by PANDA silencing. Degradation of p53 protein by silencing PANDA was prevented by treatment of MG132, a proteasome inhibitor. Moreover, depletion of PANDA prevented accumulation of p53 protein, as a result of DNA damage, induced by the genotoxic agent etoposide. These results suggest that PANDA stabilizes p53 protein in response to DNA damage, and provide new insight into the regulatory mechanisms of p53. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  17. Green tea catechin (-)-epicatechin gallate induces tumour suppressor protein ATF3 via EGR-1 activation.

    PubMed

    Cho, Kyou-Nam; Sukhthankar, Mugdha; Lee, Seong-Ho; Yoon, Joo-Heon; Baek, Seung Joon

    2007-11-01

    Epicatechin gallate (ECG) is the third major catechin component in green tea, but it shows strong biological activity in some aspects, including apoptosis, cell growth inhibition, and membrane transport system in various cells. We previously reported that ECG induces activating transcription factor 3 (ATF3), which is involved in pro-apoptosis in HCT-116 cells. In this report, we present a molecular mechanism by which ECG induces ATF3 expression at the transcriptional level. We found that Sp3 contributed to the basal expression of the ATF3 gene, whereas EGR-1 played an important role in ECG-induced ATF3 expression in HCT-116 cells, as assessed by EMSA and co-transfection experiments. These results suggested that EGR-1, a tumour suppressor protein, could substantiate ECG's role of ATF3 expression in human colorectal cancer cells. We also found that pro-oxidant activity of ECG contributed to ECG-induced ATF3 expression.

  18. Critical role of CAV1/caveolin-1 in cell stress responses in human breast cancer cells via modulation of lysosomal function and autophagy

    PubMed Central

    Shi, Yin; Tan, Shi-Hao; Ng, Shukie; Zhou, Jing; Yang, Na-Di; Koo, Gi-Bang; McMahon, Kerrie-Ann; Parton, Robert G; Hill, Michelle M; del Pozo, Miguel A; Kim, You-Sun; Shen, Han-Ming

    2015-01-01

    CAV1 (caveolin 1, caveolae protein, 22kDa) is well known as a principal scaffolding protein of caveolae, a specialized plasma membrane structure. Relatively, the caveolae-independent function of CAV1 is less studied. Autophagy is a process known to involve various membrane structures, including autophagosomes, lysosomes, and autolysosomes for degradation of intracellular proteins and organelles. Currently, the function of CAV1 in autophagy remains largely elusive. In this study, we demonstrate for the first time that CAV1 deficiency promotes both basal and inducible autophagy. Interestingly, the promoting effect was found mainly in the late stage of autophagy via enhancing lysosomal function and autophagosome-lysosome fusion. Notably, the regulatory function of CAV1 in lysosome and autophagy was found to be caveolae-independent, and acts through lipid rafts. Furthermore, the elevated autophagy level induced by CAV1 deficiency serves as a cell survival mechanism under starvation. Importantly, downregulation of CAV1 and enhanced autophagy level were observed in human breast cancer cells and tissues. Taken together, our data reveal a novel function of CAV1 and lipid rafts in breast cancer development via modulation of lysosomal function and autophagy. PMID:25945613

  19. The Nucleocapsid Protein of Coronaviruses Acts as a Viral Suppressor of RNA Silencing in Mammalian Cells.

    PubMed

    Cui, Lei; Wang, Haiying; Ji, Yanxi; Yang, Jie; Xu, Shan; Huang, Xingyu; Wang, Zidao; Qin, Lei; Tien, Po; Zhou, Xi; Guo, Deyin; Chen, Yu

    2015-09-01

    RNA interference (RNAi) is a process of eukaryotic posttranscriptional gene silencing that functions in antiviral immunity in plants, nematodes, and insects. However, recent studies provided strong supports that RNAi also plays a role in antiviral mechanism in mammalian cells. To combat RNAi-mediated antiviral responses, many viruses encode viral suppressors of RNA silencing (VSR) to facilitate their replication. VSRs have been widely studied for plant and insect viruses, but only a few have been defined for mammalian viruses currently. We identified a novel VSR from coronaviruses, a group of medically important mammalian viruses including Severe acute respiratory syndrome coronavirus (SARS-CoV), and showed that the nucleocapsid protein (N protein) of coronaviruses suppresses RNAi triggered by either short hairpin RNAs or small interfering RNAs in mammalian cells. Mouse hepatitis virus (MHV) is closely related to SARS-CoV in the family Coronaviridae and was used as a coronavirus replication model. The replication of MHV increased when the N proteins were expressed in trans, while knockdown of Dicer1 or Ago2 transcripts facilitated the MHV replication in mammalian cells. These results support the hypothesis that RNAi is a part of the antiviral immunity responses in mammalian cells. IMPORTANCE RNAi has been well known to play important antiviral roles from plants to invertebrates. However, recent studies provided strong supports that RNAi is also involved in antiviral response in mammalian cells. An important indication for RNAi-mediated antiviral activity in mammals is the fact that a number of mammalian viruses encode potent suppressors of RNA silencing. Our results demonstrate that coronavirus N protein could function as a VSR through its double-stranded RNA binding activity. Mutational analysis of N protein allowed us to find out the critical residues for the VSR activity. Using the MHV-A59 as the coronavirus replication model, we showed that ectopic expression

  20. The Nucleocapsid Protein of Coronaviruses Acts as a Viral Suppressor of RNA Silencing in Mammalian Cells

    PubMed Central

    Cui, Lei; Wang, Haiying; Ji, Yanxi; Yang, Jie; Xu, Shan; Huang, Xingyu; Wang, Zidao; Qin, Lei; Tien, Po; Zhou, Xi

    2015-01-01

    ABSTRACT RNA interference (RNAi) is a process of eukaryotic posttranscriptional gene silencing that functions in antiviral immunity in plants, nematodes, and insects. However, recent studies provided strong supports that RNAi also plays a role in antiviral mechanism in mammalian cells. To combat RNAi-mediated antiviral responses, many viruses encode viral suppressors of RNA silencing (VSR) to facilitate their replication. VSRs have been widely studied for plant and insect viruses, but only a few have been defined for mammalian viruses currently. We identified a novel VSR from coronaviruses, a group of medically important mammalian viruses including Severe acute respiratory syndrome coronavirus (SARS-CoV), and showed that the nucleocapsid protein (N protein) of coronaviruses suppresses RNAi triggered by either short hairpin RNAs or small interfering RNAs in mammalian cells. Mouse hepatitis virus (MHV) is closely related to SARS-CoV in the family Coronaviridae and was used as a coronavirus replication model. The replication of MHV increased when the N proteins were expressed in trans, while knockdown of Dicer1 or Ago2 transcripts facilitated the MHV replication in mammalian cells. These results support the hypothesis that RNAi is a part of the antiviral immunity responses in mammalian cells. IMPORTANCE RNAi has been well known to play important antiviral roles from plants to invertebrates. However, recent studies provided strong supports that RNAi is also involved in antiviral response in mammalian cells. An important indication for RNAi-mediated antiviral activity in mammals is the fact that a number of mammalian viruses encode potent suppressors of RNA silencing. Our results demonstrate that coronavirus N protein could function as a VSR through its double-stranded RNA binding activity. Mutational analysis of N protein allowed us to find out the critical residues for the VSR activity. Using the MHV-A59 as the coronavirus replication model, we showed that ectopic

  1. Interferon-Inducible Protein 16: Insight into the Interaction with Tumor Suppressor p53

    SciTech Connect

    Liao, Jack C.C.; Lam, Robert; Brazda, Vaclav; Duan, Shili; Ravichandran, Mani; Ma, Justin; Xiao, Ting; Tempel, Wolfram; Zuo, Xiaobing; Wang, Yun-Xing; Chirgadze, Nickolay Y.; Arrowsmith, Cheryl H.

    2011-08-24

    IFI16 is a member of the interferon-inducible HIN-200 family of nuclear proteins. It has been implicated in transcriptional regulation by modulating protein-protein interactions with p53 tumor suppressor protein and other transcription factors. However, the mechanisms of interaction remain unknown. Here, we report the crystal structures of both HIN-A and HIN-B domains of IFI16 determined at 2.0 and 2.35 {angstrom} resolution, respectively. Each HIN domain comprises a pair of tightly packed OB-fold subdomains that appear to act as a single unit. We show that both HIN domains of IFI16 are capable of enhancing p53-DNA complex formation and transcriptional activation via distinctive means. HIN-A domain binds to the basic C terminus of p53, whereas the HIN-B domain binds to the core DNA-binding region of p53. Both interactions are compatible with the DNA-bound state of p53 and together contribute to the effect of full-length IFI16 on p53-DNA complex formation and transcriptional activation.

  2. Simultaneous detection of the tumor suppressor FHIT gene and protein using the multi-functional biochip.

    PubMed

    Askari, Minoo D F; Miller, Gordon H; Vo-Dinh, Tuan

    2002-01-01

    The tumor suppressor gene, fragile histidine triad (FHIT), encompasses the most common human chromosomal fragile site, at 3pl4.2. Detection of FHIT gene is important in cancer diagnostics since its alterations have been associated with several human cancers. A unique multi-functional biochip for simultaneous detection of FHIT DNA and FHIT protein on the same platform was applied. The design of the biochip is based on miniaturization of photodiodes, where functioning of multiple optical sensing elements, amplifiers, discriminators, and logic circuitry are integrated on a single IC board. Performance of biochip is based on biomolecular recognition processes using both DNA and protein bioreceptors, Cy5-labeled probes and laser excitation. Application of biochip for concurrent detection of various immobilized target DNA and protein molecules and multiplex of DNA and protein on the same microarray was accomplished. Linearity of biochip for quantitative measurements was demonstrated. Results demonstrated utility of this multi-functional biochip as a useful detection technology with applications in biological and clinical laboratories.

  3. Tumor suppressor protein C53 antagonizes checkpoint kinases to promote cyclin-dependent kinase 1 activation.

    PubMed

    Jiang, Hai; Wu, Jianchun; He, Chen; Yang, Wending; Li, Honglin

    2009-04-01

    Cyclin-dependent kinase 1 (Cdk1)/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 (also known as Cdk5rap3 and LZAP) potentiates DNA damage-induced cell death by modulating the G2/M checkpoint. More recently, Wang et al. (2007) found that C53/LZAP may function as a tumor suppressor by way of inhibiting NF-kappaB signaling. We report here the identification of C53 protein as a novel regulator of Cdk1 activation. We found that knockdown of C53 protein causes delayed Cdk1 activation and mitotic entry. During DNA damage response, activation of checkpoint kinase 1 and 2 (Chk1 and Chk2) is partially inhibited by C53 overexpression. Intriguingly, we found that C53 interacts with Chk1 and antagonizes its function. Moreover, a portion of C53 protein is localized at the centrosome, and centrosome-targeting C53 potently promotes local Cdk1 activation. Taken together, our results strongly suggest that C53 is a novel negative regulator of checkpoint response. By counteracting Chk1, C53 promotes Cdk1 activation and mitotic entry in both unperturbed cell-cycle progression and DNA damage response.

  4. A disease-associated frameshift mutation in caveolin-1 disrupts caveolae formation and function through introduction of a de novo ER retention signal.

    PubMed

    Copeland, Courtney A; Han, Bing; Tiwari, Ajit; Austin, Eric D; Loyd, James E; West, James D; Kenworthy, Anne K

    2017-09-13

    Caveolin-1 (CAV1) is an essential component of caveolae and is implicated in numerous physiological processes. Recent studies have identified heterozygous mutations in the CAV1 gene in patients with pulmonary arterial hypertension (PAH), but the mechanisms by which these mutations impact caveolae assembly and contribute to disease remain unclear. To address this question, we examined the consequences of a familial PAH-associated frameshift mutation in CAV1, P158PfsX22, on caveolae assembly and function. We show that C-terminus of the CAV1 P158 protein contains a functional ER-retention signal that inhibits ER exit and caveolae formation and accelerates CAV1 turnover in Cav1(-/-) MEFs. Moreover, when co-expressed with WT CAV1 in Cav1(-/-) MEFs, CAV1-P158 functions as a dominant negative by partially disrupting WT CAV1 trafficking. In patient skin fibroblasts, CAV1 and caveolar accessory protein levels are reduced, fewer caveolae are observed, and CAV1 complexes exhibit biochemical abnormalities. Patient fibroblasts also exhibit decreased resistance to a hypo-osmotic challenge, suggesting the function of caveolae as membrane reservoir is compromised. We conclude that the P158PfsX22 frameshift introduces a gain of function that gives rise to a dominant negative form of CAV1, defining a new mechanism by which disease-associated mutations in CAV1 impair caveolae assembly. © 2017 by The American Society for Cell Biology.

  5. Impaired Cd14 and Cd36 expression, bacterial clearance, and Toll-like receptor 4-Myd88 signaling in caveolin-1-deleted macrophages and mice.

    PubMed

    Tsai, Tsung-Huang; Chen, Shu-Fen; Huang, Tai-Yu; Tzeng, Chun-Fu; Chiang, Ann-Shyn; Kou, Yu Ru; Lee, Tzong-Shyuan; Shyue, Song-Kun

    2011-01-01

    An overwhelming immune response, particularly from macrophages, with gram-negative bacteria-induced sepsis plays a critical role in survival of and organ damage in infected patients. Caveolin-1 (Cav-1), a major structure protein of caveolae, regulates many cellular functions. We examined the vital role of Cav-1 in the response of macrophages and mice to bacteria or LPS exposure. Deletion of Cav-1 decreased the expression of CD14 and CD36 during macrophage differentiation and suppressed their phagocytotic ability. As well, the ability to kill bacteria was inhibited in Cav-1 macrophages and mice peritoneal cavity, tissue, and plasma, which was partly attributed to hindered expression of iNOS induced by bacteria or LPS. Furthermore, deletion of Cav-1 attenuated the expression of Toll-like receptor 4 and myeloid differentiation factor 88 and the activation of nuclear factor κB, all of which impeded the production of inflammatory cytokines in response to bacterial exposure in Cav-1 macrophages and mice. Thus, Cav-1 participates in the regulation of CD14, CD36, Toll-like receptor 4 and myeloid differentiation factor 88 protein expression and is crucial for the immune response of macrophages to bacterial infection. Cav-1 may be a therapeutic target in the treatment of sepsis.

  6. CEACAM6 cross-linking induces caveolin-1-dependent, Src-mediated focal adhesion kinase phosphorylation in BxPC3 pancreatic adenocarcinoma cells.

    PubMed

    Duxbury, Mark S; Ito, Hiromichi; Ashley, Stanley W; Whang, Edward E

    2004-05-28

    Despite lacking transmembrane or intracellular domains, glycosylphosphatidylinositol-anchored proteins can modulate intracellular signaling events, in many cases through aggregation within membrane "lipid raft" microdomains. CEACAM6 is a glycosylphosphatidylinositol-linked cell surface protein of importance in the anchorage-independent survival and metastasis of pancreatic adenocarcinoma cells. We examined the effects of antibody-mediated cross-linking of CEACAM6 on intracellular signaling events and anchorage-independent survival of the CEACAM6-overexpressing pancreatic ductal adenocarcinoma cell line, BxPC3. CEACAM6 cross-linking increased c-Src activation and induced tyrosine phosphorylation of p125(FAK) focal adhesion kinase. Focal adhesion kinase phosphorylation was dependent on c-Src kinase activation, for which caveolin-1 was required. CEACAM6 cross-linking induced a significant increase in cellular resistance to anoikis. These observations represent the first characterization of the mechanism through which this important cell surface oncoprotein influences intracellular signaling events and hence malignant cellular behavior.

  7. How the other half lives, the amino-terminal domain of the retinoblastoma tumor suppressor protein.

    PubMed

    Goodrich, David W

    2003-11-01

    The retinoblastoma tumor suppressor gene (RB1) is currently the only known gene whose mutation is necessary and sufficient for the development of a human cancer. Mutation or deregulation of RB1 is observed so frequently in other tumor types that compromising RB1 function may be a prerequisite for malignant transformation. Identifying the molecular mechanisms that provide the basis for RB1-mediated tumor suppression has become an important goal in the quest to understand and treat cancer. The lion's share of research on these mechanisms has focused on the carboxy-terminal half of the RB1 encoded protein (pRB). This focus is with good reason since this part of the protein, now called the "large pocket," is required for most of its known activities identified in vitro and in vivo. Large pocket mediated mechanisms alone, however, cannot account for all observed properties of pRB. The thesis presented here is that the relatively uncharacterized amino-terminal half of the protein makes important contributions to pRB-mediated tumor suppression. The goals of this review are to summarize evidence indicating that an amino-terminal structural domain is important for pRB function and to suggest a general hypothesis as to how this domain can be integrated with current models of pRB function.

  8. Slit-Robo GTPase-Activating Protein 2 as a metastasis suppressor in osteosarcoma.

    PubMed

    Marko, Tracy A; Shamsan, Ghaidan A; Edwards, Elizabeth N; Hazelton, Paige E; Rathe, Susan K; Cornax, Ingrid; Overn, Paula R; Varshney, Jyotika; Diessner, Brandon J; Moriarity, Branden S; O'Sullivan, M Gerard; Odde, David J; Largaespada, David A

    2016-12-14

    Osteosarcoma is the most common primary bone tumor, with metastatic disease responsible for most treatment failure and patient death. A forward genetic screen utilizing Sleeping Beauty mutagenesis in mice previously identified potential genetic drivers of osteosarcoma metastasis, including Slit-Robo GTPase-Activating Protein 2 (Srgap2). This study evaluates the potential role of SRGAP2 in metastases-associated properties of osteosarcoma cell lines through Srgap2 knockout via the CRISPR/Cas9 nuclease system and conditional overexpression in the murine osteosarcoma cell lines K12 and K7M2. Proliferation, migration, and anchorage independent growth were evaluated. RNA sequencing and immunohistochemistry of human osteosarcoma tissue samples were used to further evaluate the potential role of the Slit-Robo pathway in osteosarcoma. The effects of Srgap2 expression modulation in the murine OS cell lines support the hypothesis that SRGAP2 may have a role as a suppressor of metastases in osteosarcoma. Additionally, SRGAP2 and other genes in the Slit-Robo pathway have altered transcript levels in a subset of mouse and human osteosarcoma, and SRGAP2 protein expression is reduced or absent in a subset of primary tumor samples. SRGAP2 and other axon guidance proteins likely play a role in osteosarcoma metastasis, with loss of SRGAP2 potentially contributing to a more aggressive phenotype.

  9. Slit-Robo GTPase-Activating Protein 2 as a metastasis suppressor in osteosarcoma

    PubMed Central

    Marko, Tracy A.; Shamsan, Ghaidan A.; Edwards, Elizabeth N.; Hazelton, Paige E.; Rathe, Susan K.; Cornax, Ingrid; Overn, Paula R.; Varshney, Jyotika; Diessner, Brandon J.; Moriarity, Branden S.; O’Sullivan, M. Gerard; Odde, David J.; Largaespada, David A.

    2016-01-01

    Osteosarcoma is the most common primary bone tumor, with metastatic disease responsible for most treatment failure and patient death. A forward genetic screen utilizing Sleeping Beauty mutagenesis in mice previously identified potential genetic drivers of osteosarcoma metastasis, including Slit-Robo GTPase-Activating Protein 2 (Srgap2). This study evaluates the potential role of SRGAP2 in metastases-associated properties of osteosarcoma cell lines through Srgap2 knockout via the CRISPR/Cas9 nuclease system and conditional overexpression in the murine osteosarcoma cell lines K12 and K7M2. Proliferation, migration, and anchorage independent growth were evaluated. RNA sequencing and immunohistochemistry of human osteosarcoma tissue samples were used to further evaluate the potential role of the Slit-Robo pathway in osteosarcoma. The effects of Srgap2 expression modulation in the murine OS cell lines support the hypothesis that SRGAP2 may have a role as a suppressor of metastases in osteosarcoma. Additionally, SRGAP2 and other genes in the Slit-Robo pathway have altered transcript levels in a subset of mouse and human osteosarcoma, and SRGAP2 protein expression is reduced or absent in a subset of primary tumor samples. SRGAP2 and other axon guidance proteins likely play a role in osteosarcoma metastasis, with loss of SRGAP2 potentially contributing to a more aggressive phenotype. PMID:27966608

  10. Differential expression patterns of metastasis suppressor proteins in basal cell carcinoma.

    PubMed

    Bozdogan, Onder; Yulug, Isik G; Vargel, Ibrahim; Cavusoglu, Tarik; Karabulut, Ayse A; Karahan, Gurbet; Sayar, Nilufer

    2015-08-01

    Basal cell carcinomas (BCCs) are common malignant skin tumors. Despite having a significant invasion capacity, they metastasize only rarely. Our aim in this study was to detect the expression patterns of the NM23-H1, NDRG1, E-cadherin, RHOGDI2, CD82/KAI1, MKK4, and AKAP12 metastasis suppressor proteins in BCCs. A total of 96 BCC and 10 normal skin samples were included for the immunohistochemical study. Eleven frozen BCC samples were also studied by quantitative real time polymerase chain reaction (qRT-PCR) to detect the gene expression profile. NM23-H1 was strongly and diffusely expressed in all types of BCC. Significant cytoplasmic expression of NDRG1 and E-cadherin was also detected. However, AKAP12 and CD82/KAI1 expression was significantly decreased. The expressions of the other proteins were somewhere between the two extremes. Similarly, qRT-PCR analysis showed down-regulation of AKAP12 and up-regulation of NM23-H1 and NDRG1 in BCC. Morphologically aggressive BCCs showed significantly higher cytoplasmic NDRG1 expression scores and lower CD82/KAI1 scores than non-aggressive BCCs. The relatively preserved levels of NM23-H1, NDRG1, and E-cadherin proteins may have a positive effect on the non-metastasizing features of these tumors. © 2014 The International Society of Dermatology.

  11. Nuclear γ-tubulin associates with nucleoli and interacts with tumor suppressor protein C53.

    PubMed

    Hořejší, Barbora; Vinopal, Stanislav; Sládková, Vladimíra; Dráberová, Eduarda; Sulimenko, Vadym; Sulimenko, Tetyana; Vosecká, Věra; Philimonenko, Anatoly; Hozák, Pavel; Katsetos, Christos D; Dráber, Pavel

    2012-01-01

    γ-Tubulin is assumed to be a typical cytosolic protein necessary for nucleation of microtubules from microtubule organizing centers. Using immunolocalization and cell fractionation techniques in combination with siRNAi and expression of FLAG-tagged constructs, we have obtained evidence that γ-tubulin is also present in nucleoli of mammalian interphase cells of diverse cellular origins. Immunoelectron microscopy has revealed γ-tubulin localization outside fibrillar centers where transcription of ribosomal DNA takes place. γ-Tubulin was associated with nucleolar remnants after nuclear envelope breakdown and could be translocated to nucleoli during mitosis. Pretreatment of cells with leptomycin B did not affect the distribution of nuclear γ-tubulin, making it unlikely that rapid active transport via nuclear pores participates in the transport of γ-tubulin into the nucleus. This finding was confirmed by heterokaryon assay and time-lapse imaging of photoconvertible protein Dendra2 tagged to γ-tubulin. Immunoprecipitation from nuclear extracts combined with mass spectrometry revealed an association of γ-tubulin with tumor suppressor protein C53 located at multiple subcellular compartments including nucleoli. The notion of an interaction between γ-tubulin and C53 was corroborated by pull-down and co-immunoprecipitation experiments. Overexpression of γ-tubulin antagonized the inhibitory effect of C53 on DNA damage G(2) /M checkpoint activation. The combined results indicate that aside from its known role in microtubule nucleation, γ-tubulin may also have nuclear-specific function(s).

  12. The role of the Suppressor of Hairy-wing insulator protein in Drosophila oogenesis

    PubMed Central

    Baxley, Ryan M.; Soshnev, Alexey A.; Koryakov, Dmitry E.; Zhimulev, Igor F.; Geyer, Pamela K.

    2011-01-01

    The Drosophila Suppressor of Hairy wing [Su(Hw)] insulator protein has an essential role in the development of the female germline. Here we investigate the function of Su(Hw) in the ovary. We show that Su(Hw) is universally expressed in somatic cells, while germ cell expression is dynamic. Robust levels accumulate in post-mitotic germ cells, where Su(Hw) localization is limited to chromosomes within nurse cells, the specialized cells that support oocyte growth. Although loss of Su(Hw) causes global defects in nurse cell chromosome structure, we demonstrate that these architectural changes are not responsible for the block in oogenesis. Connections between the fertility and insulator functions of Su(Hw) were investigated through studies of the two gypsy insulator proteins, Modifier of (mdg4)67.2 (Mod67.2) and Centrosomal Protein of 190 kD (CP190). Accumulation of these proteins is distinct from Su(Hw), with Mod67.2 and CP190 showing uniform expression in all cells during early stages of oogenesis that diminishes in later stages. Although Mod67.2 and CP190 extensively co-localize with Su(Hw) on nurse cell chromosomes, neither protein is required for nurse cell chromosome development or oocyte production. These data indicate that while the gypsy insulator function requires both Mod67.2 and CP190, these proteins are not essential for oogenesis. These studies represent the first molecular investigations of Su(Hw) function in the germline, which uncover distinct requirements for Su(Hw) insulator and ovary functions. PMID:21651900

  13. The nuclear transport receptor Importin-11 is a tumor suppressor that maintains PTEN protein

    PubMed Central

    Chen, Muhan; Nowak, Dawid G.; Narula, Navneet; Watrud, Kaitlin; Herzka, Tali M.; Zheng, Wu; Ebbesen, Saya H.; Wang, Victoria M.Y.; Nasar, Abu; Cordon-Cardo, Carlos; Wilkinson, John E.; Powers, Scott; Sordella, Raffaella; Altorki, Nasser K.; Stiles, Brendon M.

    2017-01-01

    Phosphatase and tensin homologue (PTEN) protein levels are critical for tumor suppression. However, the search for a recurrent cancer-associated gene alteration that causes PTEN degradation has remained futile. In this study, we show that Importin-11 (Ipo11) is a transport receptor for PTEN that is required to physically separate PTEN from elements of the PTEN degradation machinery. Mechanistically, we find that the E2 ubiquitin-conjugating enzyme and IPO11 cargo, UBE2E1, is a limiting factor for PTEN degradation. Using in vitro and in vivo gene-targeting methods, we show that Ipo11 loss results in degradation of Pten, lung adenocarcinoma, and neoplasia in mouse prostate with aberrantly high levels of Ube2e1 in the cytoplasm. These findings explain the correlation between loss of IPO11 and PTEN protein in human lung tumors. Furthermore, we find that IPO11 status predicts disease recurrence and progression to metastasis in patients choosing radical prostatectomy. Thus, our data introduce the IPO11 gene as a tumor-suppressor locus, which is of special importance in cancers that still retain at least one intact PTEN allele. PMID:28193700

  14. The nuclear transport receptor Importin-11 is a tumor suppressor that maintains PTEN protein.

    PubMed

    Chen, Muhan; Nowak, Dawid G; Narula, Navneet; Robinson, Brian; Watrud, Kaitlin; Ambrico, Alexandra; Herzka, Tali M; Zeeman, Martha E; Minderer, Matthias; Zheng, Wu; Ebbesen, Saya H; Plafker, Kendra S; Stahlhut, Carlos; Wang, Victoria M Y; Wills, Lorna; Nasar, Abu; Castillo-Martin, Mireia; Cordon-Cardo, Carlos; Wilkinson, John E; Powers, Scott; Sordella, Raffaella; Altorki, Nasser K; Mittal, Vivek; Stiles, Brendon M; Plafker, Scott M; Trotman, Lloyd C

    2017-03-06

    Phosphatase and tensin homologue (PTEN) protein levels are critical for tumor suppression. However, the search for a recurrent cancer-associated gene alteration that causes PTEN degradation has remained futile. In this study, we show that Importin-11 (Ipo11) is a transport receptor for PTEN that is required to physically separate PTEN from elements of the PTEN degradation machinery. Mechanistically, we find that the E2 ubiquitin-conjugating enzyme and IPO11 cargo, UBE2E1, is a limiting factor for PTEN degradation. Using in vitro and in vivo gene-targeting methods, we show that Ipo11 loss results in degradation of Pten, lung adenocarcinoma, and neoplasia in mouse prostate with aberrantly high levels of Ube2e1 in the cytoplasm. These findings explain the correlation between loss of IPO11 and PTEN protein in human lung tumors. Furthermore, we find that IPO11 status predicts disease recurrence and progression to metastasis in patients choosing radical prostatectomy. Thus, our data introduce the IPO11 gene as a tumor-suppressor locus, which is of special importance in cancers that still retain at least one intact PTEN allele.

  15. Determinants of the tumor suppressor INPP4B protein and lipid phosphatase activities.

    PubMed

    Lopez, Sandra M; Hodgson, Myles C; Packianathan, Charles; Bingol-Ozakpinar, Ozlem; Uras, Fikriye; Rosen, Barry P; Agoulnik, Irina U

    2013-10-18

    The tumor suppressor INPP4B is an important regulator of phosphatidyl-inositol signaling in the cell. Reduced INPP4B expression is associated with poor outcomes for breast, prostate, and ovarian cancer patients. INPP4B contains a CX5R catalytic motif characteristic of dual-specificity phosphatases, such as PTEN. Lipid phosphatase activity of INPP4B has previously been described. In this report we show that INPP4B can dephosphorylate para-nitrophenyl phosphate (pNPP) and 6,8-difluoro-4-methylumbelliferyl (DiFMUP), synthetic phosphotyrosine analogs, suggesting that INPP4B has protein tyrosine phosphatase (PTP) activity. Using mutagenesis, we examined the functional role of specific amino acids within the INPP4B C842KSAKDR catalytic site. The K843M mutant displayed increased pNPP hydrolysis, the K846M mutant lost lipid phosphatase activity with no effect on PTP activity, and the D847E substitution ablated PTP activity and significantly reduced lipid phosphatase activity. Further, we show that INPP4B but not PTEN is able to reduce tyrosine phosphorylation of Akt1 and both the lipid and PTP activity of INPP4B likely contribute to the reduction of Akt1 phosphorylation. Taken together our data identified key residues in the INPP4B catalytic domain associated with lipid and protein phosphatase activities and found a robust downstream target regulated by INPP4B but not PTEN.

  16. Tumour suppressor death-associated protein kinase targets cytoplasmic HIF-1α for Th17 suppression

    PubMed Central

    Chou, Ting-Fang; Chuang, Ya-Ting; Hsieh, Wan-Chen; Chang, Pei-Yun; Liu, Hsin-Yu; Mo, Shu-Ting; Hsu, Tzu-Sheng; Miaw, Shi-Chuen; Chen, Ruey-Hwa; Kimchi, Adi; Lai, Ming-Zong

    2016-01-01

    Death-associated protein kinase (DAPK) is a tumour suppressor. Here we show that DAPK also inhibits T helper 17 (Th17) and prevents Th17-mediated pathology in a mouse model of autoimmunity. We demonstrate that DAPK specifically downregulates hypoxia-inducible factor 1α (HIF-1α). In contrast to the predominant nuclear localization of HIF-1α in many cell types, HIF-1α is located in both the cytoplasm and nucleus in T cells, allowing for a cytosolic DAPK–HIF-1α interaction. DAPK also binds prolyl hydroxylase domain protein 2 (PHD2) and increases HIF-1α-PHD2 association. DAPK thereby promotes the proline hydroxylation and proteasome degradation of HIF-1α. Consequently, DAPK deficiency leads to excess HIF-1α accumulation, enhanced IL-17 expression and exacerbated experimental autoimmune encephalomyelitis. Additional knockout of HIF-1α restores the normal differentiation of Dapk−/− Th17 cells and prevents experimental autoimmune encephalomyelitis development. Our results reveal a mechanism involving DAPK-mediated degradation of cytoplasmic HIF-1α, and suggest that raising DAPK levels could be used for treatment of Th17-associated inflammatory diseases. PMID:27312851

  17. Caveolin-1 deficiency leads to increased susceptibility to cell death and fibrosis in white adipose tissue: characterization of a lipodystrophic model.

    PubMed

    Martin, Sally; Fernandez-Rojo, Manuel A; Stanley, Amanda C; Bastiani, Michele; Okano, Satomi; Nixon, Susan J; Thomas, Gethin; Stow, Jennifer L; Parton, Robert G

    2012-01-01

    Caveolin-1 (CAV1) is an important regulator of adipose tissue homeostasis. In the present study we examined the impact of CAV1 deficiency on the properties of mouse adipose tissue both in vivo and in explant cultures during conditions of metabolic stress. In CAV1(-/-) mice fasting caused loss of adipose tissue mass despite a lack of hormone-sensitive lipase (HSL) phosphorylation. In addition, fasting resulted in increased macrophage infiltration, enhanced deposition of collagen, and a reduction in the level of the lipid droplet protein perilipin A (PLIN1a). Explant cultures of CAV1(-/-) adipose tissue also showed a loss of PLIN1a during culture, enhanced secretion of IL-6, increased release of lactate dehydrogenase, and demonstrated increased susceptibility to cell death upon collagenase treatment. Attenuated PKA-mediated signaling to HSL, loss of PLIN1a and increased secretion of IL-6 were also observed in adipose tissue explants of CAV1(+/+) mice with diet-induced obesity. Together these results suggest that while alterations in adipocyte lipid droplet biology support adipose tissue metabolism in the absence of PKA-mediated pro-lipolytic signaling in CAV1(-/-) mice, the tissue is intrinsically unstable resulting in increased susceptibility to cell death, which we suggest underlies the development of fibrosis and inflammation during periods of metabolic stress.

  18. Resveratrol stimulates nitric oxide production by increasing estrogen receptor alpha-Src-caveolin-1 interaction and phosphorylation in human umbilical vein endothelial cells.

    PubMed

    Klinge, Carolyn M; Wickramasinghe, Nalinie S; Ivanova, Margarita M; Dougherty, Susan M

    2008-07-01

    Epidemiological studies correlate moderate red wine consumption to reduced incidence of cardiovascular disease. Resveratrol is a polyphenolic compound in red wine that has cardioprotective effects in rodents. Although endothelial cell (EC) studies indicate that micromolar resveratrol has diverse biological activities, these concentrations are not physiologically relevant because human oral ingestion provides only brief exposure to nanomolar plasma levels. Previously, we reported that nanomolar resveratrol activated ERK1/2 signaling in bovine aortic ECs (BAECs). The goal of this study was to determine the mechanisms by which nanomolar resveratrol rapidly activates endothelial nitric oxide synthase (eNOS) in human umbilical vein ECs (HUVECs). We report for the first time that resveratrol increased interaction between estrogen receptor alpha (ER alpha), caveolin-1 (Cav-1) and c-Src, and increased phosphorylation of Cav-1, c-Src, and eNOS. Pretreatment with the lipid raft disruptor beta-methyl cyclodextrin or G alpha inhibitor pertussis toxin blocked resveratrol- and E(2)-induced eNOS activation and NO production. Depletion of endogenous ER alpha, not ERbeta, by siRNA attenuated resveratrol- and E(2)-induced ERK1/2, Src, and eNOS phosphorylation. Our data demonstrate that nanomolar resveratrol induces ER alpha-Cav-1-c-SRC interaction, resulting in NO production through a G alpha-protein-coupled mechanism. This study provides important new insights into mechanisms for the beneficial effects of resveratrol in ECs.

  19. Progression-related loss of stromal Caveolin 1 levels fosters the growth of human PC3 xenografts and mediates radiation resistance

    PubMed Central

    Panic, Andrej; Ketteler, Julia; Reis, Henning; Sak, Ali; Herskind, Carsten; Maier, Patrick; Rübben, Herbert; Jendrossek, Verena; Klein, Diana

    2017-01-01

    Despite good treatment results in localized prostate tumors, advanced disease stages usually have a pronounced resistance to chemotherapy and radiotherapy. The membrane protein caveolin-1 (Cav1) functions here as an important oncogene. Therefore we examined the impact of stromal Cav1 expression for tumor growth and sensitivity to ionizing radiation (IR). Silencing of Cav1 expression in PC3 cells resulted in increased tumor growth and a reduced growth delay after IR when compared to tumors generated by Cav1-expressing PC3 cells. The increased radiation resistance was associated with increasing amounts of reactive tumor stroma and a Cav1 re-expression in the malignant epithelial cells. Mimicking the human situation these results were confirmed using co-implantation of Cav1-silenced PC3 cells with Cav1-silenced or Cav1-expressing fibroblasts. Immunohistochemically analysis of irradiated tumors as well as human prostate tissue specimen confirmed that alterations in stromal-epithelial Cav1 expressions were accompanied by a more reactive Cav1-reduced tumor stroma after radiation and within advanced prostate cancer tissues which potentially mediates the resistance to radiation treatment. Conclusively, the radiation response of human prostate tumors is critically regulated by Cav1 expression in stromal fibroblasts. Loss of stromal Cav1 expression in advanced tumor stages may thus contribute to resistance of these tumors to radiotherapy. PMID:28112237

  20. Involvement of caveolin-1 in low shear stress-induced breast cancer cell motility and adhesion: Roles of FAK/Src and ROCK/p-MLC pathways.

    PubMed

    Xiong, Niya; Li, Shun; Tang, Kai; Bai, Hongxia; Peng, Yueting; Yang, Hong; Wu, Chunhui; Liu, Yiyao

    2017-01-01

    Tumor cells translocating to distant sites are subjected to hemodynamic shear forces during their passage in the blood vessels. Low shear stress (LSS) plays a critical role in the regulation of various aspects of tumor cells functions, including motility and adhesion. Beyond its structural role, caveolin-1 (Cav-1), the important component of caveolae, represents a modulator of several cancer-associated functions as tumor progression and metastasis. However, the role of Cav-1 in regulating tumor cells response to shear stress remains poorly explored. Here, we characterized the role of LSS and Cav-1 in mediating cell motility and adhesion on human breast carcinoma MDA-MB-231 cells. We first showed that LSS exposure promoted cell polarity and focal adhesion (FA) dynamics, thus indicating elevated cell migration. Silencing of Cav-1 leaded to a significantly lower formation of stress fibers. However, LSS exposure was able to rescue it via the alteration of actin-associated proteins expression, including ROCK, p-MLC, cofilin and filamin A. Time-lapse migration assay indicated that Cav-1 expression fostered MDA-MB-231 cells motility and LSS triggered cells to rapidly generate new lamellipodia. Furthermore, Cav-1 and LSS significantly influenced cell adhesion. Taken together, our findings provide insights into mechanisms underlying LSS triggered events mediated by downstream Cav-1, including FAK/Src and ROCK/p-MLC pathways, involved in the reorganization of the cytoskeleton, cell motility, FA dynamics and breast cancer cell adhesion.

  1. 4-cholesten-3-one suppresses lung adenocarcinoma metastasis by regulating translocation of HMGB1, HIF1α and Caveolin-1

    PubMed Central

    Ma, Jinben; Fu, Guobin; Wu, Jing; Han, Shaoxian; Zhang, Lishan; Yang, Ming; Yu, Yong; Zhang, Mengyuan; Lin, Yanliang; Wang, Yibing

    2016-01-01

    Metastasis is a great challenge in lung adenocarcinoma (ADC) therapy. Cholesterol has been implicated in ADC metastasis. 4-cholesten-3-one, as cholesterol metabolite and analog, can substitute membrane cholesterol and increase membrane fluidity. In this study, we explored the possibility that 4-cholesten-3-one inhibited ADC metastasis. Low-dose 4-cholesten-3-one significantly restrained ADC cells migration and invasion with little effects on cells viabilities. Further investigation showed that 4-cholesten-3-one promoted ROS generation, which transiently activated AMPKα1, increased HIF1α expression, reduced Bcl-2 expression and caused autophagy. AMPKα1 knockdown partly suppressed 4-cholesten-3-one-induced autophagy but, neither prevented 4-cholesten-3-one-induced upregulation of HIF1α or downregulation of Bcl-2. 4-cholesten-3-one-induced autophagy facilitated the release of HMGB1 from nuclei to cytoplasm, blocking nuclear translocation of HIF1α and activation of MMP2 and MMP9. Also, 4-cholesten-3-one induced time-dependent phosphorylation of caveolin-1, Akt and NF-κB. With increasing treatment time, 4-cholesten-3-one accelerated caveolin-1 internalization, but reduced the phosphorylation of Akt and NF-κB, and inhibited the expression of snail and twist. These data suggested that 4-cholesten-3-one could be a potential candidate for anti-metastasis of lung adenocarcinoma. PMID:27899819

  2. Sex-Dependent Expression of Caveolin 1 in Response to Sex Steroid Hormones Is Closely Associated with Development of Obesity in Rats

    PubMed Central

    Mukherjee, Rajib; Kim, Sang Woo; Choi, Myung Sook; Yun, Jong Won

    2014-01-01

    Caveolin-1 (CAV1) is a conserved group of structural membrane proteins that form special cholesterol and sphingolipid-rich compartments, especially in adipocytes. Recently, it has been reported that CAV1 is an important target protein in sex hormone-dependent regulation of various metabolic pathways, particularly in cancer and diabetes. To clarify distinct roles of CAV1 in sex-dependent obesity development, we investigated the effects of high fat diet (HFD) and sex steroid hormones on CAV1 expression in adipose tissues of male and female rats. Results of animal experiments revealed that estrogen (17-β-estradiol, E2) and androgen (dihydrotestosterone, DHT) had opposite effects on body weight gain as well as on the regulation of CAV1, hormone sensitive lipase (HSL) and uncoupling protein 1 (UCP1) in adipose tissues. Furthermore, sex hormone receptors and aromatase were differentially expressed in a sex-dependent manner in response to E2 and DHT treatments. In vivo data were confirmed using 3T3-L1 and HIB1B cell lines, where Cav1 knock down stimulated lipogenesis but suppressed sex hormone receptor signaling proteins. Most importantly, co-immunoprecipitation enabled the identification of previously unrecognized CAV1-interacting mitochondrial or lipid oxidative pathway proteins in adipose tissues. Taken together, current data showed that CAV1 may play important preventive role in the development of obesity, with more prominent effects in females, and proved to be an important target protein for the hormonal regulation of adipose tissue metabolism by manipulating sex hormone receptors and mitochondrial oxidative pathways. Therefore, we can report, for the first time, the molecular mechanism underlying the effects of sex steroid hormones in the sex-dimorphic regulation of CAV1. PMID:24608114

  3. Sex-dependent expression of caveolin 1 in response to sex steroid hormones is closely associated with development of obesity in rats.

    PubMed

    Mukherjee, Rajib; Kim, Sang Woo; Choi, Myung Sook; Yun, Jong Won

    2014-01-01

    Caveolin-1 (CAV1) is a conserved group of structural membrane proteins that form special cholesterol and sphingolipid-rich compartments, especially in adipocytes. Recently, it has been reported that CAV1 is an important target protein in sex hormone-dependent regulation of various metabolic pathways, particularly in cancer and diabetes. To clarify distinct roles of CAV1 in sex-dependent obesity development, we investigated the effects of high fat diet (HFD) and sex steroid hormones on CAV1 expression in adipose tissues of male and female rats. Results of animal experiments revealed that estrogen (17-β-estradiol, E2) and androgen (dihydrotestosterone, DHT) had opposite effects on body weight gain as well as on the regulation of CAV1, hormone sensitive lipase (HSL) and uncoupling protein 1 (UCP1) in adipose tissues. Furthermore, sex hormone receptors and aromatase were differentially expressed in a sex-dependent manner in response to E2 and DHT treatments. In vivo data were confirmed using 3T3-L1 and HIB1B cell lines, where Cav1 knock down stimulated lipogenesis but suppressed sex hormone receptor signaling proteins. Most importantly, co-immunoprecipitation enabled the identification of previously unrecognized CAV1-interacting mitochondrial or lipid oxidative pathway proteins in adipose tissues. Taken together, current data showed that CAV1 may play important preventive role in the development of obesity, with more prominent effects in females, and proved to be an important target protein for the hormonal regulation of adipose tissue metabolism by manipulating sex hormone receptors and mitochondrial oxidative pathways. Therefore, we can report, for the first time, the molecular mechanism underlying the effects of sex steroid hormones in the sex-dimorphic regulation of CAV1.

  4. Cleavage of metastasis suppressor gene product KiSS-1 protein/metastin by matrix metalloproteinases.

    PubMed

    Takino, Takahisa; Koshikawa, Naohiko; Miyamori, Hisashi; Tanaka, Motohiro; Sasaki, Takuma; Okada, Yasunori; Seiki, Motoharu; Sato, Hiroshi

    2003-07-24

    A human placenta cDNA library was screened by the expression cloning method for gene products that interact with matrix metalloproteinases (MMPs), and we isolated a cDNA whose product formed a stable complex with pro-MMP-2 and pro-MMP-9. The cDNA encoded the metastasis suppressor gene KiSS-1. KiSS-1 protein was shown to form a complex with pro-MMP. KiSS-1 protein is known to be processed to peptide ligand of a G-protein-coupled receptor (hOT7T175) named metastin, and suppresses metastasis of tumors expressing the receptor. Active MMP-2, MMP-9, MT1-MMP, MT3-MMP and MT5-MMP cleaved the Gly118-Leu119 peptide bond of not only full-length KiSS-1 protein but also metastin decapeptide. Metastin decapeptide induced formation of focal adhesion and actin stress fibers in cells expressing the receptor, and digestion of metastin decapeptide by MMP abolished its ligand activity. Migration of HT1080 cells expressing hOT7T175 that harbor a high-level MMP activity was only slightly suppressed by either metastin decapeptide or MMP inhibitor BB-94 alone, but the combination of metastin decapeptide and BB-94 showed a synergistic effect in blocking cell migration. We propose that metastin could be used as an antimetastatic agent in combination with MMP inhibitor, or MMP-resistant forms of metastin could be developed and may also be efficacious.

  5. Effect of dietary sodium on vasoconstriction and eNOS-mediated vascular relaxation in caveolin-1-deficient mice.

    PubMed

    Pojoga, Luminita H; Yao, Tham M; Sinha, Sumi; Ross, Reagan L; Lin, Jeffery C; Raffetto, Joseph D; Adler, Gail K; Williams, Gordon H; Khalil, Raouf A

    2008-03-01

    Changes in dietary sodium intake are associated with changes in vascular volume and reactivity that may be mediated, in part, by alterations in endothelial nitric oxide synthase (eNOS) activity. Caveolin-1 (Cav-1), a transmembrane anchoring protein in the plasma membrane caveolae, binds eNOS and limits its translocation and activation. To test the hypothesis that endothelial Cav-1 participates in the dietary sodium-mediated effects on vascular function, we assessed vascular responses and nitric oxide (NO)-mediated mechanisms of vascular relaxation in Cav-1 knockout mice (Cav-1-/-) and wild-type control mice (WT; Cav-1+/+) placed on a high-salt (HS; 4% NaCl) or low-salt (LS; 0.08% NaCl) diet for 16 days. After the systolic blood pressure was measured, the thoracic aorta was isolated for measurement of vascular reactivity and NO production, and the heart was used for measurement of eNOS expression and/or activity. The blood pressure was elevated in HS mice treated with NG-nitro-l-arginine methyl ester and more so in Cav-1-/- than WT mice and was significantly reduced during the LS diet. Phenylephrine caused vascular contraction that was significantly reduced in Cav-1-/- (maximum 0.25 +/- 0.06 g/mg) compared with WT (0.75 +/- 0.22 g/mg) on the HS diet, and the differences were eliminated with the LS diet. Also, vascular contraction in response to membrane depolarization by high KCl (96 mM) was reduced in Cav-1-/- (0.27 +/- 0.05 g/mg) compared with WT mice (0.53 +/- 0.12 g/mg) on the HS diet, suggesting that the reduced vascular contraction is not limited to a particular receptor. Acetylcholine (10(-5) M) caused aortic relaxation in WT mice on HS (23.6 +/- 3.5%) and LS (23.7 +/- 5.5%) that was enhanced in Cav-1-/- HS (72.6 +/- 6.1%) and more so in Cav-1-/- LS mice (93.6 +/- 3.5%). RT-PCR analysis indicated increased eNOS mRNA expression in the aorta and heart, and Western blots indicated increased total eNOS and phosphorylated eNOS in the heart of Cav-1-/- compared

  6. Ligand binding and hydration in protein misfolding: insights from studies of prion and p53 tumor suppressor proteins.

    PubMed

    Silva, Jerson L; Vieira, Tuane C R G; Gomes, Mariana P B; Bom, Ana Paula Ano; Lima, Luis Mauricio T R; Freitas, Monica S; Ishimaru, Daniella; Cordeiro, Yraima; Foguel, Debora

    2010-02-16

    Protein misfolding has been implicated in a large number of diseases termed protein- folding disorders (PFDs), which include Alzheimer's disease, Parkinson's disease, transmissible spongiform encephalopathies, familial amyloid polyneuropathy, Huntington's disease, and type II diabetes. In these diseases, large quantities of incorrectly folded proteins undergo aggregation, destroying brain cells and other tissues. The interplay between ligand binding and hydration is an important component of the formation of misfolded protein species. Hydration drives various biological processes, including protein folding, ligand binding, macromolecular assembly, enzyme kinetics, and signal transduction. The changes in hydration and packing, both when proteins fold correctly or when folding goes wrong, leading to PFDs, are examined through several biochemical, biophysical, and structural approaches. Although in many cases the binding of a ligand such as a nucleic acid helps to prevent misfolding and aggregation, there are several examples in which ligands induce misfolding and assembly into amyloids. This occurs simply because the formation of structured aggregates (such as protofibrillar and fibrillar amyloids) involves decreases in hydration, formation of a hydrogen-bond network in the secondary structure, and burying of nonpolar amino acid residues, processes that also occur in the normal folding landscape. In this Account, we describe the present knowledge of the folding and misfolding of different proteins, with a detailed emphasis on mammalian prion protein (PrP) and tumoral suppressor protein p53; we also explore how ligand binding and hydration together influence the fate of the proteins. Anfinsen's paradigm that the structure of a protein is determined by its amino acid sequence is to some extent contradicted by the observation that there are two isoforms of the prion protein with the same sequence: the cellular and the misfolded isoform. The cellular isoform of PrP has a

  7. Proinflammatory S100 proteins regulate the accumulation of myeloid-derived suppressor cells.

    PubMed

    Sinha, Pratima; Okoro, Chinonyerem; Foell, Dirk; Freeze, Hudson H; Ostrand-Rosenberg, Suzanne; Srikrishna, Geetha

    2008-10-01

    Chronic inflammation is a complex process that promotes carcinogenesis and tumor progression; however, the mechanisms by which specific inflammatory mediators contribute to tumor growth remain unclear. We and others recently demonstrated that the inflammatory mediators IL-1beta, IL-6, and PGE(2) induce accumulation of myeloid-derived suppressor cells (MDSC) in tumor-bearing individuals. MDSC impair tumor immunity and thereby facilitate carcinogenesis and tumor progression by inhibiting T and NK cell activation, and by polarizing immunity toward a tumor-promoting type 2 phenotype. We now show that this population of immature myeloid cells induced by a given tumor share a common phenotype regardless of their in vivo location (bone marrow, spleen, blood, or tumor site), and that Gr1(high)CD11b(high)F4/80(-)CD80(+)IL4Ralpha(+/-)Arginase(+) MDSC are induced by the proinflammatory proteins S100A8/A9. S100A8/A9 proteins bind to carboxylated N-glycans expressed on the receptor for advanced glycation end-products and other cell surface glycoprotein receptors on MDSC, signal through the NF-kappaB pathway, and promote MDSC migration. MDSC also synthesize and secrete S100A8/A9 proteins that accumulate in the serum of tumor-bearing mice, and in vivo blocking of S100A8/A9 binding to MDSC using an anti-carboxylated glycan Ab reduces MDSC levels in blood and secondary lymphoid organs in mice with metastatic disease. Therefore, the S100 family of inflammatory mediators serves as an autocrine feedback loop that sustains accumulation of MDSC. Since S100A8/A9 activation of MDSC is through the NF-kappaB signaling pathway, drugs that target this pathway may reduce MDSC levels and be useful therapeutic agents in conjunction with active immunotherapy in cancer patients.

  8. Proinflammatory S100 Proteins Regulate the Accumulation of Myeloid-Derived Suppressor Cells1

    PubMed Central

    Sinha, Pratima; Okoro, Chinonyerem; Foell, Dirk; Freeze, Hudson H.; Ostrand-Rosenberg, Suzanne; Srikrishna, Geetha

    2009-01-01

    Chronic inflammation is a complex process that promotes carcinogenesis and tumor progression; however, the mechanisms by which specific inflammatory mediators contribute to tumor growth remain unclear. We and others recently demonstrated that the inflammatory mediators IL-1β, IL-6, and PGE2 induce accumulation of myeloid-derived suppressor cells (MDSC) in tumor-bearing individuals. MDSC impair tumor immunity and thereby facilitate carcinogenesis and tumor progression by inhibiting T and NK cell activation, and by polarizing immunity toward a tumor-promoting type 2 phenotype. We now show that this population of immature myeloid cells induced by a given tumor share a common phenotype regardless of their in vivo location (bone marrow, spleen, blood, or tumor site), and that Gr1highCD11bhighF4/80−CD80+IL4Rα+/−Arginase+ MDSC are induced by the proinflammatory proteins S100A8/A9. S100A8/A9 proteins bind to carboxylated N-glycans expressed on the receptor for advanced glycation end-products and other cell surface glycoprotein receptors on MDSC, signal through the NF-κB pathway, and promote MDSC migration. MDSC also synthesize and secrete S100A8/A9 proteins that accumulate in the serum of tumor-bearing mice, and in vivo blocking of S100A8/A9 binding to MDSC using an anti-carboxylated glycan Ab reduces MDSC levels in blood and secondary lymphoid organs in mice with metastatic disease. Therefore, the S100 family of inflammatory mediators serves as an autocrine feedback loop that sustains accumulation of MDSC. Since S100A8/A9 activation of MDSC is through the NF-κB signaling pathway, drugs that target this pathway may reduce MDSC levels and be useful therapeutic agents in conjunction with active immunotherapy in cancer patients. PMID:18802069

  9. The tumor suppressor protein menin inhibits AKT activation by regulating its cellular localization

    PubMed Central

    Wang, Yan; Ozawa, Atsushi; Zaman, Shadia; Prasad, Nijaguna B.; Chandrasekharappa, Settara C.; Agarwal, Sunita K.; Marx, Stephen J.

    2010-01-01

    Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder associated mainly with tumors of multiple endocrine organs. Mutations in the MEN1 gene that encodes for the menin protein are the predominant cause for hereditary MEN1 syndrome. Though menin is a tumor suppressor, its molecular mechanism of action has not been defined. Here we report that menin interacts with AKT1 in vitro and in vivo. Menin downregulates the level of active AKT and its kinase activity. Through interaction with AKT1, menin suppresses both AKT1 induced proliferation and anti-apoptosis in non-endocrine and endocrine cells. Confocal microscopy analysis revealed that menin regulates AKT1 in part by reducing the translocation of AKT1 from the cytoplasm to the plasma membrane during growth factor stimulation. Our findings may be generalizable to other cancers, insofar as we found that loss of menin expression was also associated with AKT activation in a mouse model of pancreatic islet adenoma. Together, our results suggest menin as an important novel negative regulator of AKT kinase activity. PMID:21127195

  10. Improved crystallization and diffraction of caffeine-induced death suppressor protein 1 (Cid1)

    SciTech Connect

    Yates, Luke A. Durrant, Benjamin P.; Barber, Michael; Harlos, Karl; Fleurdépine, Sophie; Norbury, Chris J.; Gilbert, Robert J. C.

    2015-02-21

    The use of truncation and RNA-binding mutations of caffeine induced death suppressor protein 1 (Cid1) as a means to enhance crystallogenesis leading to an improvement of X-ray diffraction resolution by 1.5 Å is reported. The post-transcriptional addition of uridines to the 3′-end of RNAs is an important regulatory process that is critical for coding and noncoding RNA stability. In fission yeast and metazoans this untemplated 3′-uridylylation is catalysed by a single family of terminal uridylyltransferases (TUTs) whose members are adapted to specific RNA targets. In Schizosaccharomyces pombe the TUT Cid1 is responsible for the uridylylation of polyadenylated mRNAs, targeting them for destruction. In metazoans, the Cid1 orthologues ZCCHC6 and ZCCHC11 uridylate histone mRNAs, targeting them for degradation, but also uridylate microRNAs, altering their maturation. Cid1 has been studied as a model TUT that has provided insights into the larger and more complex metazoan enzyme system. In this paper, two strategies are described that led to improvements both in the crystallogenesis of Cid1 and in the resolution of diffraction by ∼1.5 Å. These advances have allowed high-resolution crystallo@@graphic studies of this TUT system to be initiated.

  11. The retinoblastoma protein tumor suppressor is important for appropriate osteoblast differentiation and bone development.

    PubMed

    Berman, Seth D; Yuan, Tina L; Miller, Emily S; Lee, Eunice Y; Caron, Alicia; Lees, Jacqueline A

    2008-09-01

    Mutation of the retinoblastoma (RB) tumor suppressor gene is strongly linked to osteosarcoma formation. This observation and the documented interaction between the retinoblastoma protein (pRb) and Runx2 suggests that pRb is important in bone development. To assess this hypothesis, we used a conditional knockout strategy to generate pRb-deficient embryos that survive to birth. Analysis of these embryos shows that Rb inactivation causes the abnormal development and impaired ossification of several bones, correlating with an impairment in osteoblast differentiation. We further show that Rb inactivation acts to promote osteoblast differentiation in vitro and, through conditional analysis, establish that this occurs in a cell-intrinsic manner. Although these in vivo and in vitro differentiation phenotypes seem paradoxical, we find that Rb-deficient osteoblasts have an impaired ability to exit the cell cycle both in vivo and in vitro that can explain the observed differentiation defects. Consistent with this observation, we show that the cell cycle and the bone defects in Rb-deficient embryos can be suppressed by deletion of E2f1, a known proliferation inducer that acts downstream of Rb. Thus, we conclude that pRb plays a key role in regulating osteoblast differentiation by mediating the inhibition of E2F and consequently promoting cell cycle exit.

  12. Human ribosomal protein L9 is a Bax suppressor that promotes cell survival in yeast.

    PubMed

    Eid, Rawan; Sheibani, Sara; Gharib, Nada; Lapointe, Jason F; Horowitz, Avital; Vali, Hojatollah; Mandato, Craig A; Greenwood, Michael T

    2014-05-01

    The identification of a human ribosomal protein L9 (hRPL9) cDNA as a sequence capable of suppressing the lethal effects of heterologously expressed murine Bax in yeast led us to investigate its antiapoptotic potential. Using growth and viability assays, we show that yeast cells heterologously expressing hRPL9 are resistant to the growth inhibitory and lethal effects of exogenously supplied copper, indicating that it has pro-survival properties. To explore potential mechanisms, we used yeast mutants defective in all three types of programmed cell death (apoptosis, necrosis, and autophagy). The ability to retain pro-survival function in all the mutants suggests that hRPL9 may regulate a common pro-death process. In contrast, the yeast RPL9 orthologues, RPL9A and RPL9B, have opposite effects when overexpressed in yeast. In effect, instead of showing resistance to stress, RPL9A and RPL9B overexpressing cells show reduced cell growth. Further analysis indicates that the effects of overexpressed RPL9A and RPL9B are not in themselves lethal, instead, they serve to increase cell doubling time. Thus, yeast RPL9s are more representative of RPs whose extra-ribosomal function is similar to that of tumor suppressors. Taken together, our results demonstrate that RPL9 represents a species- and sequence-specific regulator of cell growth and survival.

  13. The p53 tumor suppressor protein protects against chemotherapeutic stress and apoptosis in human medulloblastoma cells

    PubMed Central

    Parasido, Erika; Tricoli, Lucas; Sivakumar, Angiela; Mikhaiel, John P.; Yenugonda, Venkata; Rodriguez, Olga C.; Karam, Sana D.; Rood, Brian R.; Avantaggiati, Maria Laura; Albanese, Chris

    2015-01-01

    Medulloblastoma (MB), a primitive neuroectodermal tumor, is the most common malignant childhood brain tumor and remains incurable in about a third of patients. Currently, survivors carry a significant burden of late treatment effects. The p53 tumor suppressor protein plays a crucial role in influencing cell survival in response to cellular stress and while the p53 pathway is considered a key determinant of anti-tumor responses in many tumors, its role in cell survival in MB is much less well defined. Herein, we report that the experimental drug VMY-1-103 acts through induction of a partial DNA damage-like response as well induction of non-survival autophagy. Surprisingly, the genetic or chemical silencing of p53 significantly enhanced the cytotoxic effects of both VMY and the DNA damaging drug, doxorubicin. The inhibition of p53 in the presence of VMY revealed increased late stage apoptosis, increased DNA fragmentation and increased expression of genes involved in apoptosis, including CAPN12 and TRPM8, p63, p73, BIK, EndoG, CIDEB, P27Kip1 and P21cip1. These data provide the groundwork for additional studies on VMY as a therapeutic drug and support further investigations into the intriguing possibility that targeting p53 function may be an effective means of enhancing clinical outcomes in MB. PMID:26540407

  14. Green tea polyphenols down-regulate caveolin-1 expression via ERK1/2 and p38MAPK in endothelial cells.

    PubMed

    Li, Yanrong; Ying, Chenjiang; Zuo, Xuezhi; Yi, Haiwei; Yi, Weijie; Meng, Yi; Ikeda, Katsumi; Ye, Xiaolei; Yamori, Yukio; Sun, Xiufa

    2009-12-01

    Caveolin-1 (Cav-1), a negative regulator of endothelial nitric oxide synthase (eNOS), influences various aspects of the cardiovascular functions. We had reported that a high-fat diet up-regulated aortic Cav-1 expressions in rats. In this study, we investigated the effects of green tea polyphenols (GTPs) on endothelial Cav-1 expression and phosphorylation in vitro. Bovine aortic endothelial cells (BAECs) were treated with 4 microg/ml GTPs for 0, 4, 8, 12, 16 and 24 h, and with 0, 0.04, 0.4, 4 and 40 microg/ml GTPs for 16 h, respectively. Cav-1 protein and mRNA were detected using Western blot and reverse transcriptase polymerase chain reaction. Cav-1 protein expression was down-regulated after treatment of BAECs with 4 microg/ml GTPs for 12, 16 and 24 h. And decrease in the level of Cav-1 mRNA was observed after GTP treatment for 4 and 8 h. GTPs (0.04-4 microg/ml) down-regulate Cav-1 protein expressions and mRNA levels dose dependently. PD98059, an inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2), up-regulated Cav-1 expression in BAECs alone and abolished the down-regulation effects of GTPs in BAECs while pretreatment with it. Inhibition of p38 mitogen-activated protein kinase (p38MAPK) with SB203580, which down-regulates Cav-1 expression in BAECs alone, deteriorated the Cav-1 down-regulating effects by GTPs. In addition to the effects on expression of Cav-1, GTP treatment inhibited phosphorylation of Cav-1 [tyrosine 14 (Tyr14)]. These data indicate that GTPs down-regulate gene expression of Cav-1 time- and dose- dependently via activating ERK1/2 and inhibiting p38MAPK signaling.

  15. Regulation of SGLT expression and localization through Epac/PKA-dependent caveolin-1 and F-actin activation in renal proximal tubule cells.

    PubMed

    Lee, Yu Jin; Kim, Mi Ok; Ryu, Jung Min; Han, Ho Jae

    2012-04-01

    This study demonstrated that exchange proteins directly activated by cAMP (Epac) and protein kinase A (PKA) by 8-bromo (8-Br)-adenosine 3',5'-cyclic monophosphate (cAMP) stimulated [(14)C]-α-methyl-D-glucopyranoside (α-MG) uptake through increased sodium-glucose cotransporters (SGLTs) expression and translocation to lipid rafts in renal proximal tubule cells (PTCs). In PTCs, SGLTs were colocalized with lipid raft caveolin-1 (cav-1), disrupted by methyl-β-cyclodextrin (MβCD). Selective activators of Epac or PKA, 8-Br-cAMP, and forskolin stimulated expressions of SGLTs and α-MG uptake in PTCs. In addition, 8-Br-cAMP-induced PKA and Epac activation increased phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and nuclear factor kappa B (NF-κB), which were involved in expressions of SGLTs. Furthermore, 8-Br-cAMP stimulated SGLTs translocation to lipid rafts via filamentous actin (F-actin) organization, which was blocked by cytochalasin D. In addition, cav-1 and SGLTs stimulated by 8-Br-cAMP were detected in lipid rafts, which were blocked by cytochalasin D. Furthermore, 8-Br-cAMP-induced SGLTs translocation and α-MG uptake were attenuated by inhibition of cav-1 activation with cav-1 small interfering RNA (siRNA) and inhibition of F-actin organization with TRIO and F-actin binding protein (TRIOBP). In conclusion, 8-Br-cAMP stimulated α-MG uptake via Epac and PKA-dependent SGLTs expression and trafficking through cav-1 and F-actin in PTCs.

  16. Evidence that selenium binding protein 1 is a tumor suppressor in prostate cancer.

    PubMed

    Ansong, Emmanuel; Ying, Qi; Ekoue, Dede N; Deaton, Ryan; Hall, Andrew R; Kajdacsy-Balla, Andre; Yang, Wancai; Gann, Peter H; Diamond, Alan M

    2015-01-01

    Selenium-Binding Protein 1 (SBP1, SELENBP1, hSP56) is a selenium-associated protein shown to be at lower levels in tumors, and its lower levels are frequently predictive of a poor clinical outcome. Distinguishing indolent from aggressive prostate cancer is a major challenge in disease management. Associations between SBP1 levels, tumor grade, and disease recurrence following prostatectomy were investigated by duplex immunofluorescence imaging using a tissue microarray containing tissue from 202 prostate cancer patients who experienced biochemical (PSA) recurrence after prostatectomy and 202 matched control patients whose cancer did not recur. Samples were matched by age, ethnicity, pathological stage and Gleason grade, and images were quantified using the Vectra multispectral imaging system. Fluorescent labels were targeted for SBP1 and cytokeratins 8/18 to restrict scoring to tumor cells, and cell-by-cell quantification of SBP1 in the nucleus and cytoplasm was performed. Nuclear SBP1 levels and the nuclear to cytoplasm ratio were inversely associated with tumor grade using linear regression analysis. Following classification of samples into quartiles based on the SBP1 levels among controls, tumors in the lowest quartile were more than twice as likely to recur compared to those in any other quartile. Inducible ectopic SBP1 expression reduced the ability of HCT-116 human tumor cells to grow in soft agar, a measure of transformation, without affecting proliferation. Cells expressing SBP1 also demonstrated a robust induction in the phosphorylation of the p53 tumor suppressor at serine 15. These data indicate that loss of SBP1 may play an independent contributing role in prostate cancer progression and its levels might be useful in distinguishing indolent from aggressive disease.

  17. Evidence That Selenium Binding Protein 1 Is a Tumor Suppressor in Prostate Cancer

    PubMed Central

    Ansong, Emmanuel; Ying, Qi; Ekoue, Dede N.; Deaton, Ryan; Hall, Andrew R.; Kajdacsy-Balla, Andre; Yang, Wancai; Gann, Peter H.; Diamond, Alan M.

    2015-01-01

    Selenium-Binding Protein 1 (SBP1, SELENBP1, hSP56) is a selenium-associated protein shown to be at lower levels in tumors, and its lower levels are frequently predictive of a poor clinical outcome. Distinguishing indolent from aggressive prostate cancer is a major challenge in disease management. Associations between SBP1 levels, tumor grade, and disease recurrence following prostatectomy were investigated by duplex immunofluorescence imaging using a tissue microarray containing tissue from 202 prostate cancer patients who experienced biochemical (PSA) recurrence after prostatectomy and 202 matched control patients whose cancer did not recur. Samples were matched by age, ethnicity, pathological stage and Gleason grade, and images were quantified using the Vectra multispectral imaging system. Fluorescent labels were targeted for SBP1 and cytokeratins 8/18 to restrict scoring to tumor cells, and cell-by-cell quantification of SBP1 in the nucleus and cytoplasm was performed. Nuclear SBP1 levels and the nuclear to cytoplasm ratio were inversely associated with tumor grade using linear regression analysis. Following classification of samples into quartiles based on the SBP1 levels among controls, tumors in the lowest quartile were more than twice as likely to recur compared to those in any other quartile. Inducible ectopic SBP1 expression reduced the ability of HCT-116 human tumor cells to grow in soft agar, a measure of transformation, without affecting proliferation. Cells expressing SBP1 also demonstrated a robust induction in the phosphorylation of the p53 tumor suppressor at serine 15. These data indicate that loss of SBP1 may play an independent contributing role in prostate cancer progression and its levels might be useful in distinguishing indolent from aggressive disease. PMID:25993660

  18. Cellular retinol binding protein 1 could be a tumor suppressor gene in cervical cancer

    PubMed Central

    Mendoza-Rodriguez, Mónica; Arreola, Hugo; Valdivia, Alejandra; Peralta, Raúl; Serna, Humberto; Villegas, Vanessa; Romero, Pablo; Alvarado-Hernández, Beatriz; Paniagua, Lucero; Marrero-Rodríguez, Daniel; Meraz, Marco A; Salcedo, Mauricio

    2013-01-01

    Aims: Cervical Cancer (CC) is one of the most important health problems in women. It frequently presents genetic changes at chromosome region 3q21. This region contains the Cellular Retinol Binding Protein 1 gene (CRBP1) which has been implicated as an important element in the development of other types of cancer. The main goal of the present work was to determine the molecular alterations of CRBP1 and its relationship to CC. Methods: To determine the molecular alterations of CRBP1 gene in CC; twenty-six CC and twenty-six healthy cervix samples were evaluated for: 1) Copy number gain by real-time PCR analysis, 2) expression levels by an immunohistochemistry assay on tissue microarray, and 3) the methylation status of the CRBP1 promoter region. Results: The increase in CRBP1 copy number was observed in 10 out of the 26 CC samples analyzed, while healthy cervices samples showed no changes in the copy number. In addition, there was a lack of expression of the CRBP1 gene in an important number of the CC samples (17/26), and the CRBP1 gene promoter was methylated in 15/26 of the CC samples. Interestingly, there was a significant association between the lack of expression of the CRBP1 gene and its methylation status. Conclusions: The data indicates that, both activating and inactivating changes in the CRBP1 gene could be significant events in the development and progression of CC, and the lack of expression of the CRBP1 protein could be related with to the development of CC. We believe that there is enough evidence to consider to CRBP1 gene as a tumor suppressor gene for CC. PMID:24040446

  19. The regulation of tumor suppressor protein, p53, and estrogen receptor (ERα) by resveratrol in breast cancer cells

    PubMed Central

    Saluzzo, Julieta; Hallman, Kelly M.; Aleck, Katie; Dwyer, Brigitte; Quigley, Meghan; Mladenovik, Viktoria; Siebert, Amy E.; Dinda, Sumi

    2016-01-01

    Resveratrol (RES) is a natural antioxidant found abundantly in grapes, peanuts, and berries, and is known to possess anti-tumorigenic properties. However, there is a noticeable lack of studies on the mechanistic effects of Resveratrol on tumor suppressors. Previous studies from our laboratory have shown the tumor suppressor protein p53 and estrogen receptor-alpha (ERα) to be possible molecular targets for RES. In this study, the anti-estrogenic effects of RES were analyzed on the expression of ERα and p53. The breast cancer cells grown in stripped serum were treated with 60 μM RES, as the optimum concentration based on data obtained from a concentration study using 1-100 μM RES. Our studies indicate that RES caused a decrease in the levels of protein expression of p53 and ERα as compared to the control. Increasing concentrations of RES caused a four-fold decrease in cell number in comparison to estradiol. RES, in conjunction with ICI 182,780 (ICI), caused a down-regulation of both p53 and ERα as compared to the control. These observed effects on cell proliferation and regulation of both p53 and ERα by RES may lead to further understanding of the relationship between tumor suppressor proteins and steroid receptors in breast cancer cells. PMID:28191286

  20. Potential RNA Binding Proteins in Saccharomyces Cerevisiae Identified as Suppressors of Temperature-Sensitive Mutations in Npl3

    PubMed Central

    Henry, M.; Borland, C. Z.; Bossie, M.; Silver, P. A.

    1996-01-01

    The NPL3 gene of the yeast Saccharomyces cerevisiae encodes a protein with similarity to heterogeneous nuclear ribonucleoproteins (hnRNPs). Npl3p has been implicated in many nuclear-related events including RNA export, protein import, and rRNA processing. Several temperature-sensitive alleles of NPL3 have been isolated. We now report the sequence of these alleles. For one allele, npl3-1, four complementation groups of suppressors have been isolated. The cognate genes for the two recessive mutants were cloned. One of these is the previously known RNA15, which, like NPL3, also encodes a protein with similarity to the vertebrate hnRNP A/B protein family. The other suppressor corresponds to a newly defined gene we term HRP1, which also encodes a protein with similarity to the hnRNP A/B proteins of vertebrates. Mutations in HRP1 suppress all npl3 temperature-sensitive alleles but do not bypass an npl3 null allele. We show that HRP1 is essential for cell growth and that the corresponding protein is located in the nucleus. The discovery of two hnRNP homologues that can partially suppress the function of Np13p, also an RNA binding protein, will be discussed in terms of the possible roles for Npl3p in RNA metabolism. PMID:8770588

  1. Differential Effects of Caveolin-1 and -2 Knockdown on Aqueous Outflow and Altered Extracellular Matrix Turnover in Caveolin-Silenced Trabecular Meshwork Cells

    PubMed Central

    Aga, Mini; Bradley, John M.; Wanchu, Rohan; Yang, Yong-feng; Acott, Ted S.; Keller, Kate E.

    2014-01-01

    Purpose. A single nucleotide polymorphism (SNP) identified between caveolin-1 (CAV1) and caveolin-2 (CAV2) on chromosome 7 is associated with glaucoma. One function of CAVs is endocytosis and recycling of extracellular matrix (ECM) components. Here, we generated CAV-silencing lentivirus to evaluate the effects on ECM turnover by trabecular meshwork (TM) cells and to measure the effect on outflow facility in anterior segment perfusion culture. Methods. Short hairpin CAV1 and CAV2 silencing and control lentivirus were generated, characterized, and applied to anterior segments in perfusion culture. Colocalization of CAVs with various ECM molecules in TM cells was investigated using immunofluorescence and confocal microscopy. Western immunoblotting and fluorogenic-based enzyme activity assays were used to investigate ECM protein levels and degradation, respectively. Results. Endogenous CAVs colocalized with cortactin at podosome- or invadopodia-like structures (PILS), which are areas of focal ECM degradation. In perfusion culture, outflow rates increased significantly in CAV1-silenced anterior segments, whereas outflow significantly decreased in CAV2-silenced anterior segments. Matrix metalloproteinase (MMP)2 and MMP14, and a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4) colocalized with both CAVs in TM cells. Protein levels and enzyme activities of MMP/ADAMTS4, fibronectin protein levels, actin stress fibers, and α-smooth muscle actin were all increased in CAV-silenced cells. Conclusions. Caveolin-mediated endocytosis is one mechanism by which TM cells can alter the physiological catabolism of ECM in order to change the composition of the outflow channels in the TM to regulate aqueous outflow resistance. Dysregulation of CAV function could contribute to the pathological changes in ECM that are observed in glaucoma. PMID:25103269

  2. Metronomic Ceramide Analogs Inhibit Angiogenesis in Pancreatic Cancer through Up-regulation of Caveolin-1 and Thrombospondin-1 and Down-regulation of Cyclin D112

    PubMed Central

    Bocci, Guido; Fioravanti, Anna; Orlandi, Paola; Di Desidero, Teresa; Natale, Gianfranco; Fanelli, Giovanni; Viacava, Paolo; Naccarato, Antonio Giuseppe; Francia, Giulio; Danesi, Romano

    2012-01-01

    Aims To evaluate the antitumor and antiangiogenic activity of metronomic ceramide analogs and their relevant molecular mechanisms. Methods Human endothelial cells [human dermal microvascular endothelial cells and human umbilical vascular endothelial cell (HUVEC)] and pancreatic cancer cells (Capan-1 and MIA PaCa-2) were treated with the ceramide analogs (C2, AL6, C6, and C8), at low concentrations for 144 hours to evaluate any antiproliferative and proapoptotic effects and inhibition of migration and to measure the expression of caveolin-1 (CAV-1) and thrombospondin-1 (TSP-1) mRNAs by real-time reverse transcription-polymerase chain reaction. Assessment of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and Akt phosphorylation and of CAV-1 and cyclin D1 protein expression was performed by ELISA. Maximum tolerated dose (MTD) gemcitabine was compared against metronomic doses of the ceramide analogs by evaluating the inhibition of MIA PaCa-2 subcutaneous tumor growth in nude mice. Results Metronomic ceramide analogs preferentially inhibited cell proliferation and enhanced apoptosis in endothelial cells. Low concentrations of AL6 and C2 caused a significant inhibition of HUVEC migration. ERK1/2 and Akt phosphorylation were significantly decreased after metronomic ceramide analog treatment. Such treatment caused the overexpression of CAV-1 and TSP-1 mRNAs and proteins in endothelial cells, whereas cyclin D1 protein levels were reduced. The antiangiogenic and antitumor impact in vivo of metronomic C2 and AL6 regimens was similar to that caused by MTD gemcitabine. Conclusions Metronomic C2 and AL6 analogs have antitumor and antiangiogenic activity, determining the up-regulation of CAV-1 and TSP-1 and the suppression of cyclin D1. PMID:23019415

  3. Genome-Wide CRISPR Screen Identifies Regulators of Mitogen-Activated Protein Kinase as Suppressors of Liver Tumors in Mice.

    PubMed

    Song, Chun-Qing; Li, Yingxiang; Mou, Haiwei; Moore, Jill; Park, Angela; Pomyen, Yotsawat; Hough, Soren; Kennedy, Zachary; Fischer, Andrew; Yin, Hao; Anderson, Daniel G; Conte, Darryl; Zender, Lars; Wang, Xin Wei; Thorgeirsson, Snorri; Weng, Zhiping; Xue, Wen

    2017-04-01

    suppressor genes not previously associated with liver cancer (Nf1, Plxnb1, Flrt2, and B9d1). CRISPR-mediated knockout of Nf1, a negative regulator of RAS, accelerated liver tumor formation in mice. Loss of Nf1 or activation of RAS up-regulated the liver progenitor cell markers HMGA2 and SOX9. RAS pathway inhibitors suppressed the activation of the Hmga2 and Sox9 genes that resulted from loss of Nf1 or oncogenic activation of RAS. Knockdown of HMGA2 delayed formation of xenograft tumors from cells that expressed oncogenic RAS. In human HCCs, low levels of NF1 messenger RNA or high levels of HMGA2 messenger RNA were associated with shorter patient survival time. Liver cancer cells with inactivation of Plxnb1, Flrt2, and B9d1 formed more tumors in mice and had increased levels of mitogen-activated protein kinase phosphorylation. Using a CRISPR-based strategy, we identified Nf1, Plxnb1, Flrt2, and B9d1 as suppressors of liver tumor formation. We validated the observation that RAS signaling, via mitogen-activated protein kinase, contributes to formation of liver tumors in mice. We associated decreased levels of NF1 and increased levels of its downstream protein HMGA2 with survival times of patients with HCC. Strategies to inhibit or reduce HMGA2 might be developed to treat patients with liver cancer. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

  4. Physical and functional interactions between the Wwox tumor suppressor protein and the AP-2gamma transcription factor.

    PubMed

    Aqeilan, Rami I; Palamarchuk, Alexey; Weigel, Ronald J; Herrero, Juan J; Pekarsky, Yuri; Croce, Carlo M

    2004-11-15

    The WWOX gene encodes a tumor suppressor WW domain-containing protein, Wwox. Alterations of WWOX have been demonstrated in multiple types of cancer, and introduction of Wwox into Wwox-negative tumor cells has resulted in tumor suppression and apoptosis. The Wwox protein contains two WW domains that typically bind proline-rich motifs and mediate protein-protein interactions. Recently, we have described functional cross-talk between the Wwox protein and the p53 homologue, p73. To further explore the biological function of Wwox, we investigated other interacting candidates. In this report, we demonstrate a physical and functional association between AP-2gamma transcription factor and the Wwox protein. AP-2gamma at 20q13.2 encodes a transcription factor and is frequently amplified in breast carcinoma. We show that Wwox binds to the PPPY motif of AP-2gamma via its first WW domain. Alterations of tyrosine 33 in the first WW domain of Wwox or the proline-rich motif in AP-2gamma dramatically reduce this interaction. In addition, our results demonstrate that Wwox expression triggers redistribution of nuclear AP-2gamma to the cytoplasm, hence suppressing its transactivating function. Our results suggest that Wwox tumor suppressor protein inhibits AP-2gamma oncogenic activity by sequestering it in the cytoplasm.

  5. Regulator of G protein signaling 6 is a novel suppressor of breast tumor initiation and progression.

    PubMed

    Maity, Biswanath; Stewart, Adele; O'Malley, Yunxia; Askeland, Ryan W; Sugg, Sonia L; Fisher, Rory A

    2013-08-01

    Breast cancer is a large global health burden and the most frequently diagnosed malignancy in women worldwide. Here, we utilize RGS6(-/-) mice to interrogate the role of regulator of G protein signaling 6 (RGS6), localized to the ductal epithelium in mouse and human breast, as a novel tumor suppressor in vivo. RGS6(-/-) mice exhibit accelerated 7,12-dimethylbenza[α]anthracene (DMBA)-induced tumor initiation and progression, as well as decreased overall survival. Analysis of carcinogenic aberrations in the mammary glands of DMBA-treated mice revealed a failure of the DNA damage response concurrent with augmented oncogenesis in RGS6(-/-) animals. Furthermore, RGS6 suppressed cell growth induced by either human epidermal growth factor receptor 2 or estrogen receptor activation in both MCF-7 breast cancer cells and mammary epithelial cells (MECs). MECs isolated from RGS6(-/-) mice also showed a deficit in DMBA-induced ATM/p53 activation, reactive oxygen species generation and apoptosis confirming that RGS6 is required for effective activation of the DNA damage response in these cells, a critical countermeasure against carcinogen-mediated genotoxic stress. The ability of RGS6 to simultaneously enhance DNA-damage-induced apoptotic signaling and suppress oncogenic cell growth likely underlie the accelerated tumorigenesis and cellular transformation observed in DMBA-treated RGS6(-/-) mice and isolated MECs, respectively. Unsurprisingly, spontaneous tumor formation was also seen in old female RGS6(-/-) but not in wild-type mice. Our finding that RGS6 is downregulated in all human breast cancer subtypes independent of their molecular classification indicates that obtaining a means to restore the growth suppressive and pro-apoptotic actions of RGS6 in breast might be a viable means to treat a large spectrum of breast tumors.

  6. MicroRNA-23b* targets proline oxidase, a mitochondrial tumor suppressor protein in renal cancer

    PubMed Central

    Liu, W; Zabirnyk, O; Wang, H; Shiao, Y-H; Nickerson, M L; Khalil, S; Anderson, L M; Perantoni, A O; Phang, J M

    2010-01-01

    Proline oxidase (POX) is a novel mitochondrial tumor suppressor, which can suppress proliferation and induce apoptosis through the generation of reactive oxygen species (ROS) and decreasing hypoxia inducible factor (HIF) signaling. Recent studies have demonstrated the absent expression of POX in human cancer tissues, including renal cancer. However, the mechanism for the loss of POX remains obscure. No genetic or epigenetic variation of POX gene was found. Here, we identified the up-regulated miR-23b* in renal cancer as an important regulator of POX. Ectopic overexpression of miR-23b* in normal renal cells resulted in striking down-regulation of POX, while POX expression increased markedly when endogenous miR-23b* was knocked down by its antagomirs in renal cancer cells. Consistent with POX-mediated tumor suppression pathway, these antagomirs induced ROS, inhibited HIF signaling and increased apoptosis. Furthermore, we confirmed the regulation of miR-23b* on POX and its function in the DLD1 Tet-off POX cell system. Using a luciferase reporter system, we verified the direct binding of miR-23b* to POX mRNA 3′UTR. In addition, pairs of human renal carcinoma and normal tissues showed the negative correlation between miR-23b* and POX protein expression, providing its clinical corroboration. Taken together, our results suggested miR-23b*, by targeting POX, could function as an oncogene; decreasing miR-23b* expression may prove to be an effective way of inhibiting kidney tumor growth. PMID:20562915

  7. Thioredoxin interacting protein (TXNIP) is a novel tumor suppressor in thyroid cancer

    PubMed Central

    2014-01-01

    Background Thyroid cancer is the most common endocrine malignancy, and many patients with metastatic differentiated thyroid cancer (DTC), poorly differentiated thyroid cancer (PDTC), and anaplastic thyroid cancer (ATC) fail to respond to conventional therapies, resulting in morbidity and mortality. Additional therapeutic targets and treatment options are needed for these patients. We recently reported that peroxisome proliferator-activated receptor gamma (PPARγ) is highly expressed in ATC and confers an aggressive phenotype when overexpressed in DTC cells. Methods Microarray analysis was used to identify downstream targets of PPARγ in ATC cells. Western blot analysis and immunohistochemistry (IHC) were used to assess thioredoxin interacting protein (TXNIP) expression in thyroid cancer cell lines and primary tumor specimens. Retroviral transduction was used to generate ATC cell lines that overexpress TXNIP, and assays that assess glucose uptake, viable cell proliferation, and invasion were used to characterize the in vitro properties of these cells. An orthotopic thyroid cancer mouse model was used to assess the effect of TXNIP overexpression in ATC cell lines in vivo. Results Using microarray analysis, we show that TXNIP is highly upregulated when PPARγ is depleted from ATC cells. Using Western blot analysis and IHC, we show that DTC and ATC cells exhibit differential TXNIP expression patterns. DTC cell lines and patient tumors have high TXNIP expression in contrast to low or absent expression in ATC cell lines and tumors. Overexpression of TXNIP decreases the growth of HTh74 cells compared to vector controls and inhibits glucose uptake in the ATC cell lines HTh74 and T238. Importantly, TXNIP overexpression in T238 cells results in attenuated tumor growth and decreased metastasis in an orthotopic thyroid cancer mouse model. Conclusions Our findings indicate that TXNIP functions as a tumor suppressor in thyroid cells, and its downregulation is likely important in

  8. Regulator of G protein signaling 6 is a novel suppressor of breast tumor initiation and progression

    PubMed Central

    Fisher, Rory A.

    2013-01-01

    Breast cancer is a large global health burden and the most frequently diagnosed malignancy in women worldwide. Here, we utilize RGS6− /− mice to interrogate the role of regulator of G protein signaling 6 (RGS6), localized to the ductal epithelium in mouse and human breast, as a novel tumor suppressor in vivo. RGS6− /− mice exhibit accelerated 7,12-dimethylbenza[α]anthracene (DMBA)-induced tumor initiation and progression, as well as decreased overall survival. Analysis of carcinogenic aberrations in the mammary glands of DMBA-treated mice revealed a failure of the DNA damage response concurrent with augmented oncogenesis in RGS6−/− animals. Furthermore, RGS6 suppressed cell growth induced by either human epidermal growth factor receptor 2 or estrogen receptor activation in both MCF-7 breast cancer cells and mammary epithelial cells (MECs). MECs isolated from RGS6−/− mice also showed a deficit in DMBA-induced ATM/p53 activation, reactive oxygen species generation and apoptosis confirming that RGS6 is required for effective activation of the DNA damage response in these cells, a critical countermeasure against carcinogen-mediated genotoxic stress. The ability of RGS6 to simultaneously enhance DNA-damage-induced apoptotic signaling and suppress oncogenic cell growth likely underlie the accelerated tumorigenesis and cellular transformation observed in DMBA-treated RGS6−/− mice and isolated MECs, respectively. Unsurprisingly, spontaneous tumor formation was also seen in old female RGS6−/− but not in wild-type mice. Our finding that RGS6 is downregulated in all human breast cancer subtypes independent of their molecular classification indicates that obtaining a means to restore the growth suppressive and pro-apoptotic actions of RGS6 in breast might be a viable means to treat a large spectrum of breast tumors. PMID:23598467

  9. Identification of a myeloid-derived suppressor cell cystatin-like protein that inhibits metastasis.

    PubMed

    Boutté, Angela M; Friedman, David B; Bogyo, Matthew; Min, Yongfen; Yang, Li; Lin, P Charles

    2011-08-01

    Myeloid-derived suppressor cells (MDSCs) are significantly increased in cancer patients and tumor bearing-animals. MDSCs infiltrate into tumors and promote tumor invasion and metastasis. To identify the mediator responsible for the prometastatic property of MDSCs, we used proteomics. We found neutrophilic granule protein (NGP) was decreased >2-fold in MDSCs from metastatic 4T1 tumor-bearing mice compared to nonmetastatic 67NR controls. NGP mRNA levels were decreased in bone marrow and in tumor-infiltrating MDSCs by 45 and 66%, respectively, in 4T1 tumor-bearing mice compared to 67NR controls. Interestingly, 4T1-conditioned medium reduced myeloid cell NGP expression by ∼ 40%, suggesting that a secreted factor mediates gene reduction. Sequence analysis shows a putative cystatin domain in NGP, and biochemical analysis confirms NGP a novel cathepsin inhibitor. It inhibited cathepsin B activity by nearly 40% in vitro. NGP expression in 4T1 tumor cells suppressed cell invasion, delayed primary tumor growth, and greatly reduced lung metastasis in vivo. A 2.8-fold reduction of cathepsin activity was found in tumors expressing NGP compared to controls. NGP significantly reduced tumor angiogenesis to 12.6 from 19.6 and lymphangiogenesis to 4.6 from 9.1 vessels/field. Necrosis was detectable only in NGP-expressing tumors, and the number of apoptotic cells increased to 22.4 from 8.3 in controls. Taken together, this study identifies a negative regulator of tumor metastasis in MDSCs, NGP, which is down-regulated in metastatic conditions. The finding suggests that malignant tumors promote invasion/metastasis not only through up-regulation of proteases but also down-regulation of protease inhibitors.

  10. Developmental iodine deficiency and hypothyroidism impair neural development, up-regulate caveolin-1 and down-regulate synaptophysin in rat hippocampus.

    PubMed

    Gong, J; Dong, J; Wang, Y; Xu, H; Wei, W; Zhong, J; Liu, W; Xi, Q; Chen, J

    2010-02-01

    Developmental iodine deficiency leads to inadequate thyroid hormone, which damages the hippocampus. In the present study, we implicate hippocampal caveolin-1 and synaptophysin in developmental iodine deficiency and hypothyroidism. Two developmental rat models were established: pregnant rats were administered either an iodine-deficient diet or propylthiouracil (PTU)-adulterated (5 p.p.m. or 15 p.p.m.) drinking water from gestational day 6 until postnatal day (PN) 28. Nissl staining and the levels of caveolin-1 and synaptophysin in several hippocampal subregions were assessed on PN14, PN21, PN28 and PN42. The results obtained show that surviving cells in the iodine-deficient and PTU-treated rats were lower than in controls. Up-regulation of caveolin-1 and down-regulation of synaptophysin were observed in the iodine-deficient and PTU-treated rats. Our findings implicate decreases in the number of surviving cells and alterations in the levels of caveolin-1 and synaptophysin in the impairments in neural development induced by developmental iodine deficiency and hypothyroidism.

  11. Restoration of caveolin-1 expression suppresses growth, membrane-type-4 metalloproteinase expression and metastasis-associated activities in colon cancer cells.

    PubMed

    Nimri, Lili; Barak, Hossei; Graeve, Lutz; Schwartz, Betty

    2013-11-01

    Caveolin-1 (cav-1) and flotillin-1 are two major structural proteins associated with lipid rafts in mammalian cells. The membrane-type matrix metalloproteinases (MT-MMPs) are expressed at the cell surface, hydrolyze extracellular matrix, and play an important role in cancer cell migration and metastasis. Expression of cav-1, flotillin-1, and MT4-MMP in lysates and lipid rafts of LS174T and HM-7 colon cancer cells was determined. The impact of restoration of cav-1 expression on proliferation, adhesion, motility in vitro, and growth of implanted tumors in vivo was characterized. Cav-1 is not expressed in lipid rafts of the highly metastatic colon cancer cell line (HM-7), but expressed in cytosolic fractions of the parental lower metastatic cell line (LS174T). In contrast, MT4-MMP was expressed in lipid rafts of HM-7 cells but not in LS174T cells. Overexpression of cav-1 in HM-7 cells down-regulate proliferation, viability, wound closure, adhesion to laminin, invasion, and development of filopodial and lamellipodial structures in a dose-dependent manner. Cav-1 positive HM-7 clones ceased to express MT4-MMP in their lipid rafts. Comparative proteomic analyses of lipid rafts from cav-1 positive and cav-1 negative cells demonstrated de novo expression of flotillin-1 only on the cells expressing cav-1. Xenografting control cells devoid of cav-1 in nude mice induced development of bigger tumors expressing higher levels of proliferating cell nuclear antigen as compared to mice injected with cells expressing the highest cav-1 levels. We conclude that cav-1 orchestrates and reorganize several proteins in lipid rafts, activities directly associated with reduced tumorigenic and metastatic ability of colon cancer cells.

  12. Protective Effect of Ginsenoside Rg1 on Bleomycin-Induced Pulmonary Fibrosis in Rats: Involvement of Caveolin-1 and TGF-β1 Signal Pathway.

    PubMed

    Zhan, Heqin; Huang, Feng; Ma, Wenzhuo; Zhao, Zhenghang; Zhang, Haifang; Zhang, Chong

    2016-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive disease with poor prognosis and high mortality rate. Panax Notoginseng Saponins (PNS), extracted from Panax Notoginseng as a traditional Asian medicine, displayed a significant anti-fibrosis effect in liver and lung. However, whether Ginsenoside Rg1 (Rg1), an important and active ingredient of PNS, exerts anti-fibrotic activity on IPF still remain unclear. In this study, we investigated the effect of Rg1 on bleomycin-induced pulmonary fibrosis in rats. Bleomycin (5 mg/kg body weight) was intratracheally administrated to male rats. Rg1 (18, 36 and 72 mg/kg) was orally administered on the next day after bleomycin. Lungs were harvested at day 7 and 28 for the further experiments. Histological analysis revealed that bleomycin successfully induced pulmonary fibrosis, and that Rg1 restored the histological alteration of bleomycin-induced pulmonary fibrosis (PF), significantly decreased lung coefficient, scores of alveolitis, scores of PF as well as contents of alpha smooth muscle actin (α-SMA) and hydroxyproline (Hyp) in a dose-dependent manner in PF rats. Moreover, Rg1 increased the expression levels of Caveolin-1 (Cav-1) mRNA and protein, lowered the expression of transforming growth factor-β1 (TGF-β1) mRNA and protein in the lung tissues of PF rats. These data suggest that Rg1 exhibits protective effect against bleomycin-induced PF in rats, which is potentially associated with the down-regulation of TGF-β1 and up-regulation of Cav-1.

  13. Matrix metalloproteinase-2-mediated occludin degradation and caveolin-1-mediated claudin-5 redistribution contribute to blood brain barrier damage in early ischemic stroke stage

    PubMed Central

    Liu, Jie; Jin, Xinchun; Liu, Ke J.; Liu, Wenlan

    2012-01-01

    Blood brain barrier (BBB) disruption occurs early enough to be within the thrombolytic time window, and this early ischemic BBB damage is closely associated with hemorrhagic transformation and thus emerging as a promising target for reducing the hemorrhagic complications of thrombolytic stroke therapy. However, the mechanisms underlying early ischemic BBB damage remain poorly understood. Here we investigated the early molecular events of ischemic BBB damage using in vitro oxygen-glucose deprivation (OGD) and in vivo rat middle cerebral artery occlusion (MCAO) models. Exposure of bEND3 monolayer to OGD for 2 h significantly increased its permeability to FITC-labeled dextran, and promoted the secretion of metalloproteinase-2 and 9 (MMP-2/9) and cytosolic translocation of caveolin-1 (Cav-1). This same OGD treatment also led to rapid degradation of tight junction protein occludin and dissociation of claudin-5 from the cytoskeleton, which contributed to OGD-induced endothelial barrier disruption. Using selective MMP-2/9 inhibitor SB-3CT or their neutralizing antibodies or Cav-1 siRNA, we found that MMP-2 was the major enzyme mediating OGD-induced occludin degradation, while Cav-1 was responsible for claudin-5 redistribution. The interaction between Cav-1 and claudin-5 was further confirmed by coimmunoprecipitation. Consistent with these in vitro findings, we observed fluorescence tracer extravasation, increased gelatinolytic activity and elevated interstitial MMP-2 levels in ischemic subcortical tissue after 2-h MCAO. Moreover, occludin protein loss and claudin-5 redistribution were detected in ischemic cerebromicrovessels. These data indicate that cerebral ischemia initiates two rapid parallel processes, MMP-2-mediated occludin degradation and Cav-1-mediated claudin-5 redistribution, to cause BBB disruption at early stroke stages relevant to acute thrombolysis. PMID:22378877

  14. Matrix metalloproteinase-2-mediated occludin degradation and caveolin-1-mediated claudin-5 redistribution contribute to blood-brain barrier damage in early ischemic stroke stage.

    PubMed

    Liu, Jie; Jin, Xinchun; Liu, Ke J; Liu, Wenlan

    2012-02-29

    Blood-brain barrier (BBB) disruption occurs early enough to be within the thrombolytic time window, and this early ischemic BBB damage is closely associated with hemorrhagic transformation and thus emerging as a promising target for reducing the hemorrhagic complications of thrombolytic stroke therapy. However, the mechanisms underlying early ischemic BBB damage remain poorly understood. Here, we investigated the early molecular events of ischemic BBB damage using in vitro oxygen-glucose deprivation (OGD) and in vivo rat middle cerebral artery occlusion (MCAO) models. Exposure of bEND3 monolayer to OGD for 2 h significantly increased its permeability to FITC-labeled dextran and promoted the secretion of metalloproteinase-2 and -9 (MMP-2/9) and cytosolic translocation of caveolin-1 (Cav-1). This same OGD treatment also led to rapid degradation of tight junction protein occludin and dissociation of claudin-5 from the cytoskeleton, which contributed to OGD-induced endothelial barrier disruption. Using selective MMP-2/9 inhibitor SB-3CT (2-[[(4-phenoxyphenyl)sulfonyl]methyl]-thiirane) or their neutralizing antibodies or Cav-1 siRNA, we found that MMP-2 was the major enzyme mediating OGD-induced occludin degradation, while Cav-1 was responsible for claudin-5 redistribution. The interaction between Cav-1 and claudin-5 was further confirmed by coimmunoprecipitation. Consistent with these in vitro findings, we observed fluorescence tracer extravasation, increased gelatinolytic activity, and elevated interstitial MMP-2 levels in ischemic subcortical tissue after 2 h MCAO. Moreover, occludin protein loss and claudin-5 redistribution were detected in ischemic cerebromicrovessels. These data indicate that cerebral ischemia initiates two rapid parallel processes, MMP-2-mediated occludin degradation and Cav-1-mediated claudin-5 redistribution, to cause BBB disruption at early stroke stages relevant to acute thrombolysis.

  15. Down-regulation of Connexin43 expression reveals the involvement of caveolin-1 containing lipid rafts in human U251 glioblastoma cell invasion.

    PubMed

    Strale, Pierre-Olivier; Clarhaut, Jonathan; Lamiche, Coralie; Cronier, Laurent; Mesnil, Marc; Defamie, Norah

    2012-11-01

    Glioblastoma cells are characterized by high proliferation and invasive capacities. Tumor development has been associated with a decrease of gap-junctional intercellular communication, but the concrete involvement of gap junction proteins, connexins, remains elusive since they are also suspected to promote cell invasion. In order to better understand how connexins control the glioma cell phenotype, we studied the consequences of inhibiting the intrinsic expression of the major astrocytic connexin, Connexin43, in human U251 glioblastoma cells by the shRNA strategy. The induced down-regulation of Cx43 expression has various effects on the U251 cells such as increased clonogenicity, angiogenesis and decreased adhesion on specific extracellular matrix proteins. We demonstrate that the invasion capacity measured in vitro and ex vivo correlates with Cx43 expression level. For the first time in a cancer cell context, our work demonstrates that Cx43 cofractionates, colocalizes and coimmunoprecipitates with a lipid raft marker, caveolin-1 and that this interaction is inversely correlated to the level of Cx43. This localization of Cx43 in these lipid raft microdomains regulates both homo- and heterocellular gap junctional communications (respectively between U251 cells, or between U251 cells and astrocytes). Moreover, the adhesive and invasive capacities are not dependent, in our model, on Cav-1 expression level. Our results tend to show that heterocellular gap junctional communication between cancer and stroma cells may affect the behavior of the tumor cells. Altogether, our data demonstrate that Cx43 controls the tumor phenotype of glioblastoma U251 cells and in particular, invasion capacity, through its localization in lipid rafts containing Cav-1.

  16. The yeast omnipotent suppressor SUP46 encodes a ribosomal protein which is a functional and structural homolog of the Escherichia coli S4 ram protein.

    PubMed

    Vincent, A; Liebman, S W

    1992-10-01

    The accurate synthesis of proteins is crucial to the existence of a cell. In yeast, several genes that affect the fidelity of translation have been identified (e.g., omnipotent suppressors, antisuppressors and allosuppressors). We have found that the dominant omnipotent suppressor SUP46 encodes the yeast ribosomal protein S13. S13 is encoded by two similar genes, but only the sup46 copy of the gene is able to fully complement the recessive phenotypes of SUP46 mutations. Both copies of the S13 genes contain introns. Unlike the introns of other duplicated ribosomal protein genes which are highly diverged, the duplicated S13 genes have two nearly identical DNA sequences of 25 and 31 bp in length within their introns. The SUP46 protein has significant homology to the S4 ribosomal protein in prokaryotic-type ribosomes. S4 is encoded by one of the ram (ribosomal ambiguity) genes in Escherichia coli which are the functional equivalent of omnipotent suppressors in yeast. Thus, SUP46 and S4 demonstrate functional as well as sequence conservation between prokaryotic and eukaryotic ribosomal proteins. SUP46 and S4 are most similar in their central amino acid sequences. Interestingly, the alterations resulting from the SUP46 mutations and the segment of the S4 protein involved in binding to the 16S rRNA are within this most conserved region.

  17. Distinct modulatory role of RNA in the aggregation of the tumor suppressor protein p53 core domain.

    PubMed

    Kovachev, Petar Stefanov; Banerjee, Debapriya; Rangel, Luciana Pereira; Eriksson, Jonny; Pedrote, Murilo M; Martins-Dinis, Mafalda Maria D C; Edwards, Katarina; Cordeiro, Yraima; Silva, Jerson L; Sanyal, Suparna

    2017-06-02

    Inactivation of the tumor suppressor protein p53 by mutagenesis, chemical modification, protein-protein interaction, or aggregation has been associated with different human cancers. Although DNA is the typical substrate of p53, numerous studies have reported p53 interactions with RNA. Here, we have examined the effects of RNA of varied sequence, length, and origin on the mechanism of aggregation of the core domain of p53 (p53C) using light scattering, intrinsic fluorescence, transmission electron microscopy, thioflavin-T binding, seeding, and immunoblot assays. Our results are the first to demonstrate that RNA can modulate the aggregation of p53C and full-length p53. We found bimodal behavior of RNA in p53C aggregation. A low RNA:protein ratio (∼1:50) facilitates the accumulation of large amorphous aggregates of p53C. By contrast, at a high RNA:protein ratio (≥1:8), the amorphous aggregation of p53C is clearly suppressed. Instead, amyloid p53C oligomers are formed that can act as seeds nucleating de novo aggregation of p53C. We propose that structured RNAs prevent p53C aggregation through surface interaction and play a significant role in the regulation of the tumor suppressor protein. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. HMG-CoA reductase inhibitor improves endothelial dysfunction in spontaneous hypertensive rats via down-regulation of caveolin-1 and activation of endothelial nitric oxide synthase.

    PubMed

    Suh, Jung-Won; Choi, Dong-Ju; Chang, Hyuk-Jae; Cho, Young-Seok; Youn, Tae-Jin; Chae, In-Ho; Kim, Kwang-Il; Kim, Cheol-Ho; Kim, Hyo-Soo; Oh, Buyng-Hee; Park, Young-Bae

    2010-01-01

    Hypertension is associated with endothelial dysfunction and increased cardiovascular risk. Caveolin-1 regulates nitric oxide (NO) signaling by modulating endothelial nitric oxide synthase (eNOS). The purpose of this study was to examine whether HMG-CoA reductase inhibitor improves impaired endothelial function of the aorta in spontaneous hypertensive rat (SHR) and to determine the underlying mechanisms involved. Eight-week-old male SHR were assigned to either a control group (CON, n=11) or a rosuvastatin group (ROS, n=12), rosuvastatin (10 mg/kg/day) administered for eight weeks. Abdominal aortic rings were prepared and responses to acetylcholine (10(-9)-10(-4) M) were determined in vitro. To evaluate the potential role of NO and caveolin-1, we examined the plasma activity of NOx, eNOS, phosphorylated-eNOS and expression of caveolin-1. The relaxation in response to acetylcholine was significantly enhanced in ROS compared to CON. Expression of eNOS RNA was unchanged, whereas NOx level and phosphorylated-eNOS at serine-1177 was increased accompanied with depressed level of caveolin-1 in ROS. We conclude that 3-Hydroxy-3-methylglutaryl Coenzyme-A (HMG-CoA) reductase inhibitor can improve impaired endothelial dysfunction in SHR, and its underlying mechanisms are associated with increased NO production. Furthermore, HMG-CoA reductase inhibitor can activate the eNOS by phosphorylation related to decreased caveolin-1 abundance. These results imply the therapeutic strategies for the high blood pressure-associated endothelial dysfunction through modifying caveolin status.

  19. Regulation of intracellular beta-catenin levels by the adenomatous polyposis coli (APC) tumor-suppressor protein.

    PubMed Central

    Munemitsu, S; Albert, I; Souza, B; Rubinfeld, B; Polakis, P

    1995-01-01

    The APC tumor-suppressor protein associates with beta-catenin, a cell adhesion protein that is upregulated by the WNT1 oncogene. We examined the effects of exogenous APC expression on the distribution and amount of beta-catenin in a colorectal cancer cell containing only mutant APC. Expression of wild-type APC caused a pronounced reduction in total beta-catenin levels by eliminating an excessive supply of cytoplasmic beta-catenin indigenous to the SW480 colorectal cancer cell line. This reduction was due to an enhanced rate of beta-catenin protein degradation. Truncated mutant APC proteins, characteristic of those associated with cancer, lacked this activity. Mutational analysis revealed that the central region of the APC protein, which is typically deleted or severely truncated in tumors, was responsible for the down-regulation of beta-catenin. These results suggest that the tumor-suppressor activity of mutant APC may be compromised due to a defect in its ability to regulate beta-catenin. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:7708772

  20. A novel RNA-binding motif in omnipotent suppressors of translation termination, ribosomal proteins and a ribosome modification enzyme?

    PubMed

    Koonin, E V; Bork, P; Sander, C

    1994-06-11

    Using computer methods for database search, multiple alignment, protein sequence motif analysis and secondary structure prediction, a putative new RNA-binding motif was identified. The novel motif is conserved in yeast omnipotent translation termination suppressor SUP1, the related DOM34 protein and its pseudogene homologue; three groups of eukaryotic and archaeal ribosomal proteins, namely L30e, L7Ae/S6e and S12e; an uncharacterized Bacillus subtilis protein related to the L7A/S6e group; and Escherichia coli ribosomal protein modification enzyme RimK. We hypothesize that a new type of RNA-binding domain may be utilized to deliver additional activities to the ribosome.

  1. Caveolin-1 (CAV1) is a target of EWS/FLI-1 and a key determinant of the oncogenic phenotype and tumorigenicity of Ewing's sarcoma cells.

    PubMed

    Tirado, Oscar M; Mateo-Lozano, Silvia; Villar, Joaquín; Dettin, Luis E; Llort, Anna; Gallego, Soledad; Ban, Jozef; Kovar, Heinrich; Notario, Vicente

    2006-10-15

    Tumors of the Ewing's sarcoma family (ESFT), such as Ewing's sarcoma (EWS) and primitive neuroectodermal tumors (PNET), are highly aggressive malignancies predominantly affecting children and young adults. ESFT express chimeric transcription factors encoded by hybrid genes fusing the EWS gene with several ETS genes, most commonly FLI-1. EWS/FLI-1 proteins are responsible for the malignant phenotype of ESFT, but only few of their transcriptional targets are known. Using antisense and short hairpin RNA-mediated gene expression knockdown, array analyses, chromatin immunoprecipitation methods, and reexpression studies, we show that caveolin-1 (CAV1) is a new direct target of EWS/FLI-1 that is overexpressed in ESFT cell lines and tumor specimens and is necessary for ESFT tumorigenesis. CAV1 knockdown led to up-regulation of Snail and the concomitant loss of E-cadherin expression. Consistently, loss of CAV1 expression inhibited the anchorage-independent growth of EWS cells and markedly reduced the growth of EWS cell-derived tumors in nude mice xenografts, indicating that CAV1 promotes the malignant phenotype in EWS carcinogenesis. Reexpression of CAV1 or E-cadherin in CAV1 knockdown EWS cells rescued the oncogenic phenotype of the original EWS cells, showing that the CAV1/Snail/E-cadherin pathway plays a central role in the expression of the oncogenic transformation functions of EWS/FLI-1. Overall, these data identify CAV1 as a key determinant of the tumorigenicity of ESFT and imply that targeting CAV1 may allow the development of new molecular therapeutic strategies for ESFT patients.

  2. The interaction between caveolin-1 and Rho-GTPases promotes metastasis by controlling the expression of alpha5-integrin and the activation of Src, Ras and Erk.

    PubMed

    Arpaia, E; Blaser, H; Quintela-Fandino, M; Duncan, G; Leong, H S; Ablack, A; Nambiar, S C; Lind, E F; Silvester, J; Fleming, C K; Rufini, A; Tusche, M W; Brüstle, A; Ohashi, P S; Lewis, J D; Mak, T W

    2012-02-16

    Proteins containing a caveolin-binding domain (CBD), such as the Rho-GTPases, can interact with caveolin-1 (Cav1) through its caveolin scaffold domain. Rho-GTPases are important regulators of p130(Cas), which is crucial for both normal cell migration and Src kinase-mediated metastasis of cancer cells. However, although Rho-GTPases (particularly RhoC) and Cav1 have been linked to cancer progression and metastasis, the underlying molecular mechanisms are largely unknown. To investigate the function of Cav1-Rho-GTPase interaction in metastasis, we disrupted Cav1-Rho-GTPase binding in melanoma and mammary epithelial tumor cells by overexpressing CBD, and examined the loss-of-function of RhoC in metastatic cancer cells. Cancer cells overexpressing CBD or lacking RhoC had reduced p130(Cas) phosphorylation and Rac1 activation, resulting in an inhibition of migration and invasion in vitro. The activity of Src and the activation of its downstream targets FAK, Pyk2, Ras and extracellular signal-regulated kinase (Erk)1/2 were also impaired. A reduction in α5-integrin expression, which is required for binding to fibronectin and thus cell migration and survival, was observed in CBD-expressing cells and cells lacking RhoC. As a result of these defects, CBD-expressing melanoma cells had a reduced ability to metastasize in recipient mice, and impaired extravasation and survival in secondary sites in chicken embryos. Our data indicate that interaction between Cav1 and Rho-GTPases (most likely RhoC but not RhoA) promotes metastasis by stimulating α5-integrin expression and regulating the Src-dependent activation of p130(Cas)/Rac1, FAK/Pyk2 and Ras/Erk1/2 signaling cascades.

  3. Impact of the loss of caveolin-1 on lung mass and cholesterol metabolism in mice with and without the lysosomal cholesterol transporter, Niemann-Pick type C1.

    PubMed

    Mundy, Dorothy I; Lopez, Adam M; Posey, Kenneth S; Chuang, Jen-Chieh; Ramirez, Charina M; Scherer, Philipp E; Turley, Stephen D

    2014-07-01

    Caveolin-1 (Cav-1) is a major structural protein in caveolae in the plasma membranes of many cell types, particularly endothelial cells and adipocytes. Loss of Cav-1 function has been implicated in multiple diseases affecting the cardiopulmonary and central nervous systems, as well as in specific aspects of sterol and lipid metabolism in the liver and intestine. Lungs contain an exceptionally high level of Cav-1. Parameters of cholesterol metabolism in the lung were measured, initially in Cav-1-deficient mice (Cav-1(-/-)), and subsequently in Cav-1(-/-) mice that also lacked the lysosomal cholesterol transporter Niemann-Pick C1 (Npc1) (Cav-1(-/-):Npc1(-/-)). In 50-day-old Cav-1(-/-) mice fed a low- or high-cholesterol chow diet, the total cholesterol concentration (mg/g) in the lungs was marginally lower than in the Cav-1(+/+) controls, but due to an expansion in their lung mass exceeding 30%, whole-lung cholesterol content (mg/organ) was moderately elevated. Lung mass (g) in the Cav-1(-/-):Npc1(-/-) mice (0.356±0.022) markedly exceeded that in their Cav-1(+/+):Npc1(+/+) controls (0.137±0.009), as well as in their Cav-1(-/-):Npc1(+/+) (0.191±0.013) and Cav-1(+/+):Npc1(-/-) (0.213±0.022) littermates. The corresponding lung total cholesterol contents (mg/organ) in mice of these genotypes were 6.74±0.17, 0.71±0.05, 0.96±0.05 and 3.12±0.43, respectively, with the extra cholesterol in the Cav-1(-/-):Npc1(-/-) and Cav-1(+/+):Npc1(-/-) mice being nearly all unesterified (UC). The exacerbation of the Npc1 lung phenotype and increase in the UC level in the Cav-1(-/-):Npc1(-/-) mice imply a regulatory role of Cav-1 in pulmonary cholesterol metabolism when lysosomal sterol transport is disrupted.

  4. Caveolae and caveolin-1 are implicated in 1alpha,25(OH)2-vitamin D3-dependent modulation of Src, MAPK cascades and VDR localization in skeletal muscle cells.

    PubMed

    Buitrago, Claudia; Boland, Ricardo

    2010-07-01

    We previously reported that 1alpha,25(OH)2D3 induces non-transcriptional rapid responses through activation of MAPKs in C2C12 skeletal muscle cells. However, there is little information on the molecular mechanism underlying the initiation of 1alpha,25(OH)2D3 signaling through this pathway. Plasma membrane components have been involved in some non-genomic effects. In this work, we investigated the role of caveolae and caveolin-1 (cav-1) in 1alpha,25(OH)2D3-stimulation of c-Src and MAPKs. When proliferating cells were pretreated with methyl beta cyclodextrin (MbetaCD), a caveolae disrupting agent, under conditions in which cell morphology is not affected and no signs of apoptosis are observed, 1alpha,25(OH)2D3-dependent activation of ERK1/2, p38 MAPK and c-Src was suppressed. Similar results were obtained by siRNA technology whereby silencing of cav-1 expression abolished activation of c-Src and MAPKs induced by the hormone. By confocal immunocytochemistry it was observed that cav-1 colocalizes with c-Src in the periplasma membrane zone at basal conditions. Hormone treatment disrupted the colocalization of these proteins and redistributed them into cytoplasm and nucleus. Co-immunoprecipitation assays corroborated these observations. Changes in VDR localization after 1alpha,25(OH)2D3 exposure were also investigated. Confocal microscopy images showed that the hormone induces VDR translocation to the plasma membrane, and this effect is abolished by MbetaCD. Altogether, these data suggest that caveolae is involved upstream in c-Src-MAPKs activation by 1alpha,25(OH)2D3 and that VDR and cav-1 participate in the rapid signaling elicited by the hormone.

  5. Quantum Dots-Based Immunofluorescent Imaging of Stromal Fibroblasts Caveolin-1 and Light Chain 3B Expression and Identification of Their Clinical Significance in Human Gastric Cancer

    PubMed Central

    He, Yuyu; Zhao, Xianda; Gao, Jun; Fan, Lifang; Yang, Guifang; Cho, William Chi-shing; Chen, Honglei

    2012-01-01

    Caveolin-1 (Cav-1) expression deficiency and autophagy in tumor stromal fibroblasts (hereafter fibroblasts) are involved in tumor proliferation and progression, particularly in breast and prostate cancer. The aim of this study was to detect the expression of fibroblastic Cav-1 and LC3B, markers of autophagy, in gastric cancer (GC) and to analyze their clinical significances. Furthermore, because Epstein-Barr virus (EBV)-associated GC (EBVaGC) is a unique subtype of GC; we compared the differential expression of fibroblastic Cav-1 and LC3B in EBVaGC and non-EBVaGC. Quantum dots (QDs)-based immunofluorescence histochemistry was used to examine the expression of fibroblastic Cav-1 and LC3B in 118 cases of GC with adequate stroma. QDs-based double immunofluorescence labeling was performed to detect the coexpression of Cav-1 and LC3B proteins. EBV-encoded small RNA was detected by QDs-based fluorescence in situ hybridization to identify EBVaGC. Multivariate analysis indicated that low fibroblastic Cav-1 level was an independent prognosticator (p = 0.029) that predicted poorer survival of GC patients. Positive fibroblastic LC3B was correlated with lower invasion (p = 0.032) and was positively associated with Cav-1 expression (r = 0.432, p < 0.001). EBV infection did not affect fibroblastic Cav-1 and LC3B expression. In conclusion, positive fibroblastic LC3B correlates with lower invasion, and low expression of fibroblastic Cav-1 is a novel predictor of poor GC prognosis. PMID:23203033

  6. Valproic acid inhibits the invasion of PC3 prostate cancer cells by upregulating the metastasis suppressor protein NDRG1.

    PubMed

    Lee, Jae Eun; Kim, Jung Hwa

    2015-12-01

    Valproic acid (VPA) is a clinically available histone deacetylase inhibitor with promising anticancer attributes. Recent studies have demonstrated the anticancer effects of VPA on prostate cancer cells. However, little is known about the differential effects of VPA between metastatic and non-metastatic prostate cancer cells and the relationship between the expression of metastasis suppressor proteins and VPA. In the present study, we demonstrate that inhibition of cell viability and invasion by VPA was more effective in the metastatic prostate cancer cell line PC3 than in the tumorigenic but non-metastatic prostate cell line, RWPE2. Further, we identified that the metastasis suppressor NDRG1 is upregulated in PC3 by VPA treatment. In contrast, NDRG1 was not increased in RWPE2 cells. Also, the suppressed invasion of PC3 cells by VPA treatment was relieved by NDRG1 knockdown. Taken together, we suggest that the anticancer effect of VPA on prostate cancer cells is, in part, mediated through upregulation of NDRG1. We also conclude that VPA has differential effects on the metastasis suppressor gene and invasion ability between non-metastatic and metastatic prostate cancer cells.

  7. Multiple global suppressors of protein stability defects facilitate the evolution of extended-spectrum TEM β-lactamases

    PubMed Central

    Brown, Nicholas G.; Pennington, Jeanine M.; Huang, Wanzhi; Ayvaz, Tulin; Palzkill, Timothy

    2010-01-01

    The introduction of extended-spectrum cephalosporins and β-lactamase inhibitors has driven the evolution of extended–spectrum TEM β-lactamases (ESBLs) with the ability to hydrolyze these drugs. The evolved TEM ESBLs from clinical isolates of bacteria often contain substitutions that occur in the active site and alter the catalytic properties of the enzyme to provide increased hydrolysis of extended-spectrum cephalosporins or resistance to inhibitors. These active site substitutions often result in a cost in the form of reduced enzyme stability. The evolution of TEM ESBLs is facilitated by mutations that act as global suppressors of protein stability defects in that they allow the enzyme to absorb multiple amino acid changes despite incremental losses in stability associated with the substitutions. The best studied example is the M182T substitution that corrects protein stability defects and is commonly found in TEM-type ESBLs or inhibitor-resistant variants from clinical isolates. In this study, a genetic selection for second site mutations that could partially restore function to a severely destabilized primary mutant enabled the identification of A184V, T265M, R275Q, and N276D, which are known to occur in TEM ESBLs from clinical isolates, as suppressors of TEM-1 protein stability defects. Further characterization demonstrated that these substitutions increased the thermal stability of TEM-1 and were able to correct the stability defects of two different sets of destabilizing mutations. The acquisition of compensatory global suppressors of stability costs that are associated with active site mutations may be a common mechanism for the evolution of novel protein function. PMID:20955714

  8. Import of amber and ochre suppressor tRNAs into mammalian cells: A general approach to site-specific insertion of amino acid analogues into proteins

    PubMed Central

    Köhrer, Caroline; Xie, Liang; Kellerer, Susanne; Varshney, Umesh; RajBhandary, Uttam L.

    2001-01-01

    A general approach to site-specific insertion of amino acid analogues into proteins in vivo would be the import into cells of a suppressor tRNA aminoacylated with the analogue of choice. The analogue would be inserted at any site in the protein specified by a stop codon in the mRNA. The only requirement is that the suppressor tRNA must not be a substrate for any of the cellular aminoacyl–tRNA synthetases. Here, we describe conditions for the import of amber and ochre suppressor tRNAs derived from Escherichia coli initiator tRNA into mammalian COS1 cells, and we present evidence for their activity in the specific suppression of amber (UAG) and ochre (UAA) codons, respectively. We show that an aminoacylated amber suppressor tRNA (supF) derived from the E. coli tyrosine tRNA can be imported into COS1 cells and acts as a suppressor of amber codons, whereas the same suppressor tRNA imported without prior aminoacylation does not, suggesting that the supF tRNA is not a substrate for any mammalian aminoacyl–tRNA synthetase. These results open the possibility of using the supF tRNA aminoacylated with an amino acid analogue as a general approach for the site-specific insertion of amino acid analogues into proteins in mammalian cells. We discuss the possibility further of importing a mixture of amber and ochre suppressor tRNAs for the insertion of two different amino acid analogues into a protein and the potential use of suppressor tRNA import for treatment of some of the human genetic diseases caused by nonsense mutations. PMID:11717406

  9. Age-Related Modulations of AQP4 and Caveolin-1 in the Hippocampus Predispose the Toxic Effect of Phoneutria nigriventer Spider Venom.

    PubMed

    Soares, Edilene S; Stávale, Leila M; Mendonça, Monique C P; Coope, Andressa; Cruz-Höfling, Maria Alice da

    2016-11-23

    We have previously demonstrated that Phoneutria nigriventer venom (PNV) causes blood-brain barrier (BBB) breakdown, swelling of astrocytes end-feet and fluid permeation into brain interstitium in rats. Caveolae and water channels respond to BBB alterations by co-participation in shear stress response and edema formation/resolution. Herein, we showed post-natal developmental-related changes of two BBB-associated transporter proteins: the endothelial caveolin-1 (Cav-1), the major scaffolding protein from caveolae frame, and the astroglial aquaporin-4 (AQP4), the main water channel protein expressed in astrocytic peri-vascular end-feet processes, in the hippocampus of rats intraperitoneally-administered PNV. Western blotting protein levels; immunohistochemistry (IHC) protein distribution in CA1, CA2, and CA3 subfields; and gene expression by Real Time-Polymerase Chain Reaction (qPCR) were assessed in post-natal Day 14 (P14) and 8-10-week-old rats over critical periods of envenomation. The intensity and duration of the toxic manifestations indicate P14 neonate rats more vulnerable to PNV than adults. Histologically, the capillaries of P14 and 8-10-week-old rats treated with PNV showed perivascular edema, while controls did not. The intensity of the toxic manifestations in P14 decreases temporally (2 > 5 > 24 h), while inversely the expression of AQP4 and Cav-1 peaked at 24 h when clinically PNV-treated animals do not differ from saline controls. IHC of AQP4 revealed that hippocampal CA1 showed the least expression at 2 h when toxic manifestation was maximal. Subfield IHC quantification revealed that in P14 rats Cav-1 peaked at 24 h when toxic manifestations were absent, whereas in 8-10-week-old rats Cav-1 peaked at 2 h when toxic signs were highest, and progressively attenuated such increases until 24 h, remaining though significantly above baseline. Considering astrocyte-endothelial physical and functional interactions, we hypothesize that age-related modulations of

  10. Age-Related Modulations of AQP4 and Caveolin-1 in the Hippocampus Predispose the Toxic Effect of Phoneutria nigriventer Spider Venom

    PubMed Central

    Soares, Edilene S.; Stávale, Leila M.; Mendonça, Monique C. P.; Coope, Andressa; da Cruz-Höfling, Maria Alice

    2016-01-01

    We have previously demonstrated that Phoneutria nigriventer venom (PNV) causes blood–brain barrier (BBB) breakdown, swelling of astrocytes end-feet and fluid permeation into brain interstitium in rats. Caveolae and water channels respond to BBB alterations by co-participation in shear stress response and edema formation/resolution. Herein, we showed post-natal developmental-related changes of two BBB-associated transporter proteins: the endothelial caveolin-1 (Cav-1), the major scaffolding protein from caveolae frame, and the astroglial aquaporin-4 (AQP4), the main water channel protein expressed in astrocytic peri-vascular end-feet processes, in the hippocampus of rats intraperitoneally-administered PNV. Western blotting protein levels; immunohistochemistry (IHC) protein distribution in CA1, CA2, and CA3 subfields; and gene expression by Real Time-Polymerase Chain Reaction (qPCR) were assessed in post-natal Day 14 (P14) and 8–10-week-old rats over critical periods of envenomation. The intensity and duration of the toxic manifestations indicate P14 neonate rats more vulnerable to PNV than adults. Histologically, the capillaries of P14 and 8–10-week-old rats treated with PNV showed perivascular edema, while controls did not. The intensity of the toxic manifestations in P14 decreases temporally (2 > 5 > 24 h), while inversely the expression of AQP4 and Cav-1 peaked at 24 h when clinically PNV-treated animals do not differ from saline controls. IHC of AQP4 revealed that hippocampal CA1 showed the least expression at 2 h when toxic manifestation was maximal. Subfield IHC quantification revealed that in P14 rats Cav-1 peaked at 24 h when toxic manifestations were absent, whereas in 8–10-week-old rats Cav-1 peaked at 2 h when toxic signs were highest, and progressively attenuated such increases until 24 h, remaining though significantly above baseline. Considering astrocyte-endothelial physical and functional interactions, we hypothesize that age

  11. Ubiquitin-specific protease 11 (USP11) functions as a tumor suppressor through deubiquitinating and stabilizing VGLL4 protein

    PubMed Central

    Zhang, Encheng; Shen, Bing; Mu, Xingyu; Qin, Yan; Zhang, Fang; Liu, Yong; Xiao, Jiantao; Zhang, Pingzhao; Wang, Chenji; Tan, Mingyue; Fan, Yu

    2016-01-01

    VGLL4 is a transcriptional repressor that interacts with transcription factors TEADs and inhibits YAP-induced overgrowth and tumorigenesis. VGLL4 protein was dramatically reduced in various types of human cancers. But how VGLL4 protein is post-transcriptional regulated is poorly understood. In this study, we identify deubiquitinating enzyme USP11 as a novel VGLL4 interactor. We reveal that the USP domain of USP11 and the N-terminal region of VGLL4 are required for mutual binding. USP11 controls VGLL4 protein stability by promoting its deubiquitination. Furthermore, our results show that knockdown of USP11 promotes cell growth, migration, and invasion in a YAP-dependent manner. Together, our results suggest that USP11 may exert its tumor suppressor role by modulating VGLL4/YAP-TEADs regulatory loop. PMID:28042509

  12. Elicitation of hypersensitive responses in Nicotiana glutinosa by the suppressor of RNA silencing protein P0 from poleroviruses.

    PubMed

    Wang, Ken-Der; Empleo, Roman; Nguyen, Tan Tri V; Moffett, Peter; Sacco, Melanie Ann

    2015-06-01

    Plant disease resistance (R) proteins that confer resistance to viruses recognize viral gene products with diverse functions, including viral suppressors of RNA silencing (VSRs). The P0 protein from poleroviruses is a VSR that targets the ARGONAUTE1 (AGO1) protein for degradation, thereby disrupting RNA silencing and antiviral defences. Here, we report resistance against poleroviruses in Nicotiana glutinosa directed against Turnip yellows virus (TuYV) and Potato leafroll virus (PLRV). The P0 proteins from TuYV (P0(T) (u) ), PLRV (P0(PL) ) and Cucurbit aphid-borne yellows virus (P0(CA) ) were found to elicit a hypersensitive response (HR) in N. glutinosa accession TW59, whereas other accessions recognized P0(PL) only. Genetic analysis showed that recognition of P0(T) (u) by a resistance gene designated RPO1 (Resistance to POleroviruses 1) is inherited as a dominant allele. Expression of P0 from a Potato virus X (PVX) expression vector transferred recognition to the recombinant virus on plants expressing RPO1, supporting P0 as the unique Polerovirus factor eliciting resistance. The induction of HR required a functional P0 protein, as P0(T) (u) mutants with substitutions in the F-box motif that abolished VSR activity were unable to elicit HR. We surmised that the broad P0 recognition seen in TW59 and the requirement for the F-box protein motif could indicate detection of P0-induced AGO1 degradation and disruption of RNA silencing; however, other viral silencing suppressors, including the PVX P25 that also causes AGO1 degradation, failed to elicit HR in N. glutinosa. Investigation of P0 elicitation of RPO1 could provide insight into P0 activities within the cell that trigger resistance. © 2014 BSPP AND JOHN WILEY & SONS LTD.

  13. The Drosophila suppressor of sable gene encodes a polypeptide with regions similar to those of RNA-binding proteins.

    PubMed Central

    Voelker, R A; Gibson, W; Graves, J P; Sterling, J F; Eisenberg, M T

    1991-01-01

    The nucleotide sequence of the Drosophila melanogaster suppressor of sable [su(s)] gene has been determined. Comparison of genomic and cDNA sequences indicates that an approximately 7,860-nucleotide primary transcript is processed into an approximately 5-kb message, expressed during all stages of the life cycle, that contains an open reading frame capable of encoding a 1,322-amino-acid protein of approximately 150 kDa. The putative protein contains an RNA recognition motif-like region and a highly charged arginine-, lysine-, serine-, aspartic or glutamic acid-rich region that is similar to a region contained in several RNA-processing proteins. In vitro translation of in vitro-transcribed RNA from a complete cDNA yields a product whose size agrees with the size predicted by the open reading frame. Antisera against su(s) fusion proteins recognize the in vitro-translated protein and detect a protein of identical size in the nuclear fractions from tissue culture cells and embryos. The protein is also present in smaller amounts in cytoplasmic fractions of embryos. That the su(s) protein has regions similar in structure to RNA-processing protein is consistent with its known role in affecting the transcript levels of those alleles that it suppresses. Images PMID:1703632

  14. Oxytocin receptor elicits different EGFR/MAPK activation patterns depending on its localization in caveolin-1 enriched domains.

    PubMed

    Rimoldi, Valeria; Reversi, Alessandra; Taverna, Elena; Rosa, Patrizia; Francolini, Maura; Cassoni, Paola; Parenti, Marco; Chini, Bice

    2003-09-04

    We have recently shown that oxytocin inhibits cell proliferation when the vast majority of oxytocin receptors are excluded from caveolin-1-enriched microdomains, and that, on the contrary, it has a mitogenic effect when the receptors are targeted to these plasma membrane domains. In this study, we investigated whether the receptors located inside and outside caveolar microdomains initiate different signalling pathways and how this may lead to opposite effects on cell proliferation. Our data indicate that, depending on their localization, oxytocin receptors transactivate EGFR and activate ERK1/2 using different signalling intermediates. The final outcome is a different temporal pattern of EGFR and ERK1/2 phosphorylation, which is more persistent when the receptors are located outside caveolar microdomains and inhibit cell growth, and very transient when they are located in caveolar microdomains and stimulate cell growth. Finally, only the activation of receptors located outside caveolar microdomains correlates with the activation of the cell cycle inhibitor p21(WAF1/CIP1), thus suggesting that the antiproliferative OTR effects may, in this case, be achieved by a sustained activation of EGFR and MAPK leading to the induction of this cell cycle regulator.

  15. Human melanoma cells express FGFR/Src/Rho signaling that entails an adhesion-independent caveolin-1 membrane association.

    PubMed

    Fecchi, Katia; Travaglione, Sara; Spadaro, Francesca; Quattrini, Adriano; Parolini, Isabella; Piccaro, Giovanni; Raggi, Carla; Fabbri, Alessia; Felicetti, Federica; Carè, Alessandra; Fiorentini, Carla; Sargiacomo, Massimo

    2012-03-15

    Caveolae have been indicated as a center of cytoskeleton regulation for Src kinase/Rho GTPase signaling. In addition, Src recruitment on intact cortical actin cytoskeleton appears to be required for bFGF/FGFR signal activation. Recently, we established a relationship between caveolin-1 (Cav-1) expression and cell migration in human malignant melanoma, constitutively activated by a bFGF autoregulatory loop. This work intends to investigate whether caveolae's asset, through bFGF/FGFR/c-Src/Rho signaling, could be related to melanoma cell anchorage. Accordingly, we revealed the existence of a FGFR/Src kinase pathway in Cav-1 enriched detergent-resistant membranes (DRMs) of Me665/1 metastatic melanoma cells, as confirmed by FGFR silencing. Moreover, we determined the expression and phosphorylation levels of Cav-1/Src/Erk signal pathway as a function of FGFR activation and cell density. A sucrose density gradient ultracentrifugation was employed to monitor Cav-1 membrane association and buoyancy in Me665/1 cells treated for actin fragmentation or for altered phosphorylation signals. As a result, melanoma cells show remarkable resistance to Cav-1 disassembly, together with persisting cell signal activity, being Src and Cav-1 crucial modulators of Rho GTPases. In conclusion, our study primarily highlights, in a metastatic melanoma cell line expressing caveolin, the circumstances whereby caveola structural and functional endurance enables the FGFR/Src/Rho GTPases pathway to keep on cell progression.

  16. Evidence for Dsg3 in regulating Src signaling by competing with it for binding to caveolin-1

    PubMed Central

    Wan, Hong; Lin, Kuang; Tsang, Siu Man; Uttagomol, Jutamas

    2015-01-01

    This data article contains extended, complementary analysis related to the research articles entitled “Desmoglein 3, via an interaction with E-cadherin, is associated with activation of Src” (Tsang et al., 2010) [1] and figures related to the review article entitled “Desmoglein 3: a help or a hindrance in cancer progression?” (Brown et al., 2014) [2]. We show here that both Src and caveolin-1 (Cav-1) associate with Dsg3 in a non-ionic detergent soluble pool and that modulation of Dsg3 levels inversely alters the expression of Src in the Cav-1 complex. Furthermore, immunofluorescence analysis revealed a reduced colocalization of Cav-1/total Src in cells with overexpression of Dsg3 compared to control cells. In support, the sequence analysis has identified a region within the carboxyl-terminus of human Dsg3 for a likelihood of binding to the scaffolding domain of Cav-1, the known Src binding site in Cav-1, and this region is highly conserved across most of 18 species as well as within desmoglein family members. Based on these findings, we propose a working model that Dsg3 activates Src through competing with its inactive form for binding to Cav-1, thus leading to release of Src followed by its auto-activation. PMID:26858977

  17. The G-protein Alpha Subunit Gsα Is A Tumor Suppressor In Sonic Hedgehog-driven Medulloblastoma

    PubMed Central

    He, Xuelian; Zhang, Liguo; Chen, Ying; Remke, Marc; Shih, David; Lu, Fanghui; Wang, Haibo; Deng, Yaqi; Yu, Yang; Xia, Yong; Wu, Xiaochong; Ramaswamy, Vijay; Hu, Tom; Wang, Fan; Zhou, Wenhao; Burns, Dennis K.; Kim, Se Hoon; Kool, Marcel; Pfister, Stefan M.; Weinstein, Lee S.; Pomeroy, Scott L.; Gilbertson, Richard J.; Rubin, Joshua B.; Hou, Yiping; Wechsler-Reya, Robert; Taylor, Michael D.; Lu, Q. Richard

    2014-01-01

    Medulloblastoma, the most common malignant childhood brain tumor, exhibits distinct molecular subtypes and cellular origins. Genetic alterations driving medulloblastoma initiation and progression remain poorly understood. Herein, we identify GNAS, encoding the G-protein Gsα, as a potent tumor suppressor gene that defines a subset of aggressive Sonic Hedgehog (Shh)-driven human medulloblastomas. Ablation of the single Gnas gene in anatomically-distinct progenitors is sufficient to induce Shh-associated medulloblastomas, which recapitulate their human counterparts. Gsα is highly enriched at the primary cilium of granule neuron precursors and suppresses Shh-signaling by regulating both the cAMP-dependent pathway and ciliary trafficking of Hedgehog pathway components. Elevation of a Gsα effector, cAMP, effectively inhibits tumor cell proliferation and progression in Gnas mutants. Thus, our gain- and loss-of-function studies identify a previously unrecognized tumor suppressor function for Gsα that acts as a molecular link across Shh-group medulloblastomas of disparate cellular and anatomical origins, illuminating G-protein modulation as a potential therapeutic avenue. PMID:25150496

  18. Secreted frizzled-related protein-5 is epigenetically downregulated and functions as a tumor suppressor in kidney cancer.

    PubMed

    Kawakami, Kazumori; Yamamura, Soichiro; Hirata, Hiroshi; Ueno, Koji; Saini, Sharanjot; Majid, Shahana; Tanaka, Yuichiro; Kawamoto, Ken; Enokida, Hideki; Nakagawa, Masayuki; Dahiya, Rajvir

    2011-02-01

    Secreted frizzled-related protein-5 (sFRP-5) has been identified as 1 of the secreted antagonists that bind Wnt protein. However, the functional significance of sFRP-5 in renal cell cancer (RCC) has not been reported. We hypothesized that sFRP-5 may be epigenetically downregulated through DNA methylation and histone modification and function as a tumor suppressor gene in RCC. Using tissue microarray and real-time RT-PCR, we found that sFRP-5 was significantly downregulated in kidney cancer tissues and cell lines, respectively. DNA bisulfite sequencing of the sFRP-5 promoter region in RCC cell lines showed it to be densely methylated, whereas there was few promoter methylation in normal kidney. The sFRP-5 expression was restored and the acetylation of H3 and H4 histones associated with the sFRP-5 promoter region were significantly increased after treatment with demethylation agent (5-Aza-dc) and histone deacetylase inhibitor (TSA). When RCC cells were transfected with the sFRP-5 gene, significant inhibition of anchorage independent colony formation and cell invasion were observed compared to controls. The sFRP-5 transfection also significantly induced apoptosis in RCC cells. In conclusion, this is the first report documenting that the sFRP-5 is downregulated by promoter methylation and histone acetylation and functions as a tumor suppressor gene by inducing apoptosis in RCC cells.

  19. Yellow fever virus capsid protein is a potent suppressor of RNA silencing that binds double-stranded RNA

    PubMed Central

    Samuel, Glady Hazitha; Wiley, Michael R.; Badawi, Atif; Adelman, Zach N.; Myles, Kevin M.

    2016-01-01

    Mosquito-borne flaviviruses, including yellow fever virus (YFV), Zika virus (ZIKV), and West Nile virus (WNV), profoundly affect human health. The successful transmission of these viruses to a human host depends on the pathogen’s ability to overcome a potentially sterilizing immune response in the vector mosquito. Similar to other invertebrate animals and plants, the mosquito’s RNA silencing pathway comprises its primary antiviral defense. Although a diverse range of plant and insect viruses has been found to encode suppressors of RNA silencing, the mechanisms by which flaviviruses antagonize antiviral small RNA pathways in disease vectors are unknown. Here we describe a viral suppressor of RNA silencing (VSR) encoded by the prototype flavivirus, YFV. We show that the YFV capsid (YFC) protein inhibits RNA silencing in the mosquito Aedes aegypti by interfering with Dicer. This VSR activity appears to be broadly conserved in the C proteins of other medically important flaviviruses, including that of ZIKV. These results suggest that a molecular “arms race” between vector and pathogen underlies the continued existence of flaviviruses in nature. PMID:27849599

  20. Helium postconditioning regulates expression of caveolin-1 and -3 and induces RISK pathway activation after ischaemia/reperfusion in cardiac tissue of rats.

    PubMed

    Flick, Moritz; Albrecht, Martin; Oei, Gezina T M L; Steenstra, Renske; Kerindongo, Raphaela P; Zuurbier, Coert J; Patel, Hemal H; Hollmann, Markus W; Preckel, Benedikt; Weber, Nina C

    2016-11-15

    Caveolae, lipid enriched invaginations of the plasma membrane, are epicentres of cellular signal transduction. The structural proteins of caveolae, caveolins, regulate effector pathways in anaesthetic-induced cardioprotection, including the RISK pathway. Helium (He) postconditioning (HePoc) is known to mimic anaesthetic conditioning and to prevent damage from myocardial infarction. We hypothesize that HePoc regulates caveolin-1 and caveolin-3 (Cav-1 and Cav-3) expression in the rat heart and activates the RISK pathway. Male Wistar rats (n=8, each group) were subjected to 25min of cardiac ischaemia followed by reperfusion (I/R) for 5, 15 or 30min (I/R 5/15/30). The HePoc groups underwent I/R with 70% helium ventilation during reperfusion (IR+He 5/15/30min). Sham animals received surgical treatment without I/R. After each protocol blood and hearts were retrieved. Tissue was obtained from the area-at-risk (AAR) and non-area-at-risk (NAAR) and processed for western blot analyses and reverse-transcription-real-time-polymerase-chain-reaction (RT-qPCR). Protein analyses revealed increased amounts of Cav-1 and Cav-3 in the membrane of I/R+He15 (AAR: Cav-1, P<0.05; Cav-3, P<0.05; both vs. I/R15). In serum, Cav-3 was found to be elevated in I/R+He15 (P<0.05 vs. I/R15). RT-qPCR showed increased expression of Cav-1 in IR+He15 in AAR tissue (P<0.05 vs. I/R15). Phosphorylation of RISK pathway proteins pERK1/2 (AAR: P<0.05 vs. I/R15) and pAKT (AAR: P<0.05; NAAR P<0.05; both vs. I/R15) was elevated in the cytosolic fraction of I/R+He15. These results suggest that 15min of HePoc regulates Cav-1 and Cav-3 and activates RISK pathway kinases ERK1/2 and AKT. These processes might be crucially involved in HePoc mediated cardioprotection. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Repression of hsp70 heat shock gene transcription by the suppressor of hairy-wing protein of Drosophila melanogaster

    SciTech Connect

    Holdridge, C.; Dorsett, D. )

    1991-04-01

    The suppressor of hairy-wing [su(Hw)] locus of Drosophila melanogaster encodes a zinc finger protein that binds a repeated motif in the gypsy retroposon. Mutations of su(Hw) suppress the phenotypes associated with mutations caused by gypsy insertions. To examine the mechanisms by which su(Hw) alters gene expression, a fragment of gypsy containing multiple su(Hw) protein-binding sites was inserted into various locations in the well-characterized Drosophila hsp70 heat shock gene promoter. The authors found no evidence for activation of basal hsp70 transcription by su(Hw) protein in cultured Drosophila cells but observed that it can repress heat shock-induced transcription. Repression occurred only when su(Hw) protein-binding sites were positioned between binding sites for proteins required for heat shock transcription. They propose that su(Hw) protein interferes nonspecifically with protein-protein interactions required for heat shock transcription, perhaps sterically, or by altering the ability of DNA to bend or twist.

  2. The ω-carboxyl group of 7-ketocholesteryl-9-carboxynonanoate mediates the binding of oxLDL to CD36 receptor and enhances caveolin-1 expression in macrophages.

    PubMed

    Li, Jingda; Yu, Chengjie; Wang, Renjun; Xu, Jianrong; Chi, Yan; Qin, Jianzhong; Liu, Qingping

    2017-09-01

    CD36 signal transduction modulates the uptake of oxidized low-density lipoprotein (oxLDL) and foam cell formation. We previously observed that 7-ketocholesteryl-9-carboxynonanoate (oxLig-1), the lipid moiety of oxLDL, activates the CD36-Src-JNK/ERK1/2 signalling pathway. In this study, we assessed the role of the ω-carboxyl group in the binding of oxLig-1 to CD36 and investigated whether the binding of the ω-carboxyl group to CD36 triggers CD36-mediated signalling, thereby resulting in the upregulation of caveolin-1 expression. Our results showed that oxLig-1 bound to CD36 and that the ω-carboxyl group was critical for this binding. Furthermore, immunoprecipitation and Western blot analyses showed that interaction between the ω-carboxyl group of oxLig-1 and CD36 triggered intracellular Src-JNK/ERK1/2 signal transduction. Moreover, the binding of the ω-carboxyl group to CD36 induced caveolin-1 expression and translocation to the membrane in macrophages. Additionally, inhibitors of Src, JNK and ERK and siRNA targeting CD36 and NF-κB significantly suppressed the enhanced caveolin-1 expression induced by oxLig-1. In conclusion, these observations suggest that oxLig-1 is a critical epitope of oxLDL that mediates the binding of oxLDL to CD36 and activates downstream Src-JNK/ERK1/2-NF-κB signal transduction, resulting in upregulation of caveolin-1 expression in macrophages. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Overexpression of caveolin-1 attenuates brain edema by inhibiting tight junction degradation

    PubMed Central

    Choi, Kang-Ho; Lee, Eun-Bin; Lee, Jung-Kil; Kim, Joon-Tae; Kim, Ja-Hae; Lee, Min-Cheol; Lee, Hong-Joon; Cho, Ki-Hyun

    2016-01-01

    Cerebral edema from the disruption of the blood-brain barrier (BBB) after cerebral ischemia is a major cause of morbidity and mortality as well as a common event in patients with stroke. Caveolins (Cavs) are thought to regulate BBB functions. Here, we report for the first time that Cav-1 overexpression (OE) decreased brain edema from BBB disruption following ischemic insult. Edema volumes and Cav-1 expression levels were measured following photothrombosis and middle cerebral artery occlusion (MCAO). Endothelial cells that were transduced with a Cav-1 lentiviral expression vector were transplanted into rats. BBB permeability was quantified with Evans blue extravasation. Edema volume was determined from measures of the extravasation area, brain water content, and average fluorescence intensity after Cy5.5 injections. Tight junction (TJ) protein expression was measured with immunoblotting. Cav-1 expression levels and vasogenic brain edema correlated strongly after ischemic insult. Cav-1 expression and BBB disruption peaked 3 d after the MCAO. In addition, intravenous administration of endothelial cells expressing Cav-1 effectively increased the Cav-1 levels 3 d after the MCAO ischemic insult. Importantly, Cav-1 OE ameliorated the vasogenic edema by inhibiting the degradation of TJ protein expression in the acute phase of ischemic stroke. These results suggested that Cav-1 OE protected the integrity of the BBB mainly by preventing the degradation of TJ proteins in rats. These findings need to be confirmed in a clinical setting in human subjects. PMID:27708218

  4. Behavior of RNAi suppressor protein 2b of Cucumber mosaic virus in planta in presence and absence of virus.

    PubMed

    Praveen, Shelly; Mangrauthia, Satendra K; Singh, Priyanka; Mishra, Anil K

    2008-08-01

    The 2b protein encoded by Cucumber mosaic virus (CMV) has been shown as a virus counter defense factor that interferes with the RNAi pathway. The 2b gene from CMV-banana, New Delhi isolate (CMV-NDLS) was amplified from CMV infected cucumber plants to generate the sense and antisense binary vector constructs for 2b expression and repression in planta. Constitutive expression of 2b gene in healthy Nicotiana tabacum caused phenotypic aberrations during somatic embryogenesis, which were not observed when expressed in CMV infected N. tabacum. Further, the established virus population in CMV infected N. tabacum was not affected by constitutive expression and repression of 2b gene. Thus, indicating its role in initiation of gene silencing, at the early stage of viral infection. This is the first demonstration of differential behavior of 2b suppressor protein in host development in the absence and presence of virus.

  5. Tobacco calmodulin-like protein provides secondary defense by binding to and directing degradation of virus RNA silencing suppressors

    PubMed Central

    Nakahara, Kenji S.; Masuta, Chikara; Yamada, Syouta; Shimura, Hanako; Kashihara, Yukiko; Wada, Tomoko S.; Meguro, Ayano; Goto, Kazunori; Tadamura, Kazuki; Sueda, Kae; Sekiguchi, Toru; Shao, Jun; Itchoda, Noriko; Matsumura, Takeshi; Igarashi, Manabu; Ito, Kimihito; Carthew, Richard W.; Uyeda, Ichiro

    2012-01-01

    RNA silencing (RNAi) induced by virus-derived double-stranded RNA (dsRNA), which is in a sense regarded as a pathogen-associated molecular pattern (PAMP) of viruses, is a general plant defense mechanism. To counteract this defense, plant viruses express RNA silencing suppressors (RSSs), many of which bind to dsRNA and attenuate RNAi. We showed that the tobacco calmodulin-like protein, rgs-CaM, counterattacked viral RSSs by binding to their dsRNA-binding domains and sequestering them from inhibiting RNAi. Autophagy-like protein degradation seemed to operate to degrade RSSs with the sacrifice of rgs-CaM. These RSSs could thus be regarded as secondary viral PAMPs. This study uncovered a unique defense system in which an rgs-CaM–mediated countermeasure against viral RSSs enhanced host antiviral RNAi in tobacco. PMID:22665793

  6. Tobacco calmodulin-like protein provides secondary defense by binding to and directing degradation of virus RNA silencing suppressors.

    PubMed

    Nakahara, Kenji S; Masuta, Chikara; Yamada, Syouta; Shimura, Hanako; Kashihara, Yukiko; Wada, Tomoko S; Meguro, Ayano; Goto, Kazunori; Tadamura, Kazuki; Sueda, Kae; Sekiguchi, Toru; Shao, Jun; Itchoda, Noriko; Matsumura, Takeshi; Igarashi, Manabu; Ito, Kimihito; Carthew, Richard W; Uyeda, Ichiro

    2012-06-19

    RNA silencing (RNAi) induced by virus-derived double-stranded RNA (dsRNA), which is in a sense regarded as a pathogen-associated molecular pattern (PAMP) of viruses, is a general plant defense mechanism. To counteract this defense, plant viruses express RNA silencing suppressors (RSSs), many of which bind to dsRNA and attenuate RNAi. We showed that the tobacco calmodulin-like protein, rgs-CaM, counterattacked viral RSSs by binding to their dsRNA-binding domains and sequestering them from inhibiting RNAi. Autophagy-like protein degradation seemed to operate to degrade RSSs with the sacrifice of rgs-CaM. These RSSs could thus be regarded as secondary viral PAMPs. This study uncovered a unique defense system in which an rgs-CaM-mediated countermeasure against viral RSSs enhanced host antiviral RNAi in tobacco.

  7. The 7a accessory protein of severe acute respiratory syndrome coronavirus acts as an RNA silencing suppressor.

    PubMed

    Karjee, Sumona; Minhas, Ankita; Sood, Vikas; Ponia, Sanket S; Banerjea, Akhil C; Chow, Vincent T K; Mukherjee, Sunil K; Lal, Sunil K

    2010-10-01

    RNA silencing suppressors (RSSs) are well studied for plant viruses but are not well defined to date for animal viruses. Here, we have identified an RSS from a medically important positive-sense mammalian virus, Severe acute respiratory syndrome coronavirus. The viral 7a accessory protein suppressed both transgene and virus-induced gene silencing by reducing the levels of small interfering RNA (siRNA). The suppression of silencing was analyzed by two independent assays, and the middle region (amino acids [aa] 32 to 89) of 7a was responsible for suppression. Finally, the RNA suppression property and the enhancement of heterologous replicon activity by the 7a protein were confirmed for animal cell lines.

  8. NAM9 nuclear suppressor of mitochondrial ochre mutations in Saccharomyces cerevisiae codes for a protein homologous to S4 ribosomal proteins from chloroplasts, bacteria, and eucaryotes.

    PubMed Central

    Boguta, M; Dmochowska, A; Borsuk, P; Wrobel, K; Gargouri, A; Lazowska, J; Slonimski, P P; Szczesniak, B; Kruszewska, A

    1992-01-01

    We report the genetic characterization, molecular cloning, and sequencing of a novel nuclear suppressor, the NAM9 gene from Saccharomyces cerevisiae, which acts on mutations of mitochondrial DNA. The strain NAM9-1 was isolated as a respiration-competent revertant of a mitochondrial mit mutant which carries the V25 ochre mutation in the oxi1 gene. Genetic characterization of the NAM9-1 mutation has shown that it is a nuclear dominant omnipotent suppressor alleviating several mutations in all four mitochondrial genes tested and has suggested its informational, and probably ribosomal, character. The NAM9 gene was cloned by transformation of the recipient oxi1-V25 mutant to respiration competence by using a gene bank from the NAM9-1 rho o strain. Orthogonal-field alternation gel electrophoresis analysis and genetic mapping localized the NAM9 gene on the right arm of chromosome XIV. Sequence analysis of the NAM9 gene showed that it encodes a basic protein of 485 amino acids with a presequence that could target the protein to the mitochondrial matrix. The N-terminal sequence of 200 amino acids of the deduced NAM9 product strongly resembles the S4 ribosomal proteins from chloroplasts and bacteria. Significant although less extensive similarity was found with ribosomal cytoplasmic proteins from lower eucaryotes, including S. cerevisiae. Chromosomal inactivation of the NAM9+ gene is not lethal to the cell but leads to respiration deficiency and loss of mitochondrial DNA integrity. We conclude that the NAM9 gene product is a mitochondrial ribosomal counterpart of S4 ribosomal proteins found in other systems and that the suppressor acts through decreasing the fidelity of translation. Images PMID:1729612

  9. Cop1 constitutively regulates c-Jun protein stability and functions as a tumor suppressor in mice

    PubMed Central

    Migliorini, Domenico; Bogaerts, Sven; Defever, Dieter; Vyas, Rajesh; Denecker, Geertrui; Radaelli, Enrico; Zwolinska, Aleksandra; Depaepe, Vanessa; Hochepied, Tino; Skarnes, William C.; Marine, Jean-Christophe

    2011-01-01

    Biochemical studies have suggested conflicting roles for the E3 ubiquitin ligase constitutive photomorphogenesis protein 1 (Cop1; also known as Rfwd2) in tumorigenesis, providing evidence for both the oncoprotein c-Jun and the tumor suppressor p53 as its targets. Here we present what we believe to be the first in vivo investigation of the role of Cop1 in cancer etiology. Using an innovative genetic approach to generate an allelic series of Cop1, we found that Cop1 hypomorphic mice spontaneously developed malignancy at a high frequency in the first year of life and were highly susceptible to radiation-induced lymphomagenesis. Further analysis revealed that c-Jun was a key physiological target for Cop1 and that Cop1 constitutively kept c-Jun at low levels in vivo and thereby modulated c-Jun/AP-1 transcriptional activity. Importantly, Cop1 deficiency stimulated cell proliferation in a c-Jun–dependent manner. Focal deletions of COP1 were observed at significant frequency across several cancer types, and COP1 loss was determined to be one of the mechanisms leading to c-Jun upregulation in human cancer. We therefore conclude that Cop1 is a tumor suppressor that functions, at least in part, by antagonizing c-Jun oncogenic activity. In the absence of evidence for a genetic interaction between Cop1 and p53, our data strongly argue against the use of Cop1-inhibitory drugs for cancer therapy. PMID:21403399

  10. A Novel Method for Gene-Specific Enhancement of Protein Translation by Targeting 5'UTRs of Selected Tumor Suppressors.

    PubMed

    Master, Adam; Wójcicka, Anna; Giżewska, Kamilla; Popławski, Piotr; Williams, Graham R; Nauman, Alicja

    2016-01-01

    Translational control is a mechanism of protein synthesis regulation emerging as an important target for new therapeutics. Naturally occurring microRNAs and synthetic small inhibitory RNAs (siRNAs) are the most recognized regulatory molecules acting via RNA interference. Surprisingly, recent studies have shown that interfering RNAs may also activate gene transcription via the newly discovered phenomenon of small RNA-induced gene activation (RNAa). Thus far, the small activating RNAs (saRNAs) have only been demonstrated as promoter-specific transcriptional activators. We demonstrate that oligonucleotide-based trans-acting factors can also specifically enhance gene expression at the level of protein translation by acting at sequence-specific targets within the messenger RNA 5'-untranslated region (5'UTR). We designed a set of short synthetic oligonucleotides (dGoligos), specifically targeting alternatively spliced 5'UTRs in transcripts expressed from the THRB and CDKN2A suppressor genes. The in vitro translation efficiency of reporter constructs containing alternative TRβ1 5'UTRs was increased by up to more than 55-fold following exposure to specific dGoligos. Moreover, we found that the most folded 5'UTR has higher translational regulatory potential when compared to the weakly folded TRβ1 variant. This suggests such a strategy may be especially applied to enhance translation from relatively inactive transcripts containing long 5'UTRs of complex structure. This report represents the first method for gene-specific translation enhancement using selective trans-acting factors designed to target specific 5'UTR cis-acting elements. This simple strategy may be developed further to complement other available methods for gene expression regulation including gene silencing. The dGoligo-mediated translation-enhancing approach has the potential to be transferred to increase the translation efficiency of any suitable target gene and may have future application in gene therapy

  11. Caveolin-1 is critical for abdominal aortic aneurysm formation induced by angiotensin II and inhibition of lysyl oxidase

    PubMed Central

    Takayanagi, Takehiko; Crawford, Kevin J.; Kobayashi, Tomonori; Obama, Takashi; Tsuji, Toshiyuki; Elliott, Katherine J.; Hashimoto, Tomoki; Rizzo, Victor; Eguchi, Satoru

    2014-01-01

    Although angiotensin II (Ang II) and its receptor AT1 have been implicated in abdominal aortic aneurysm (AAA) formation, the proximal signaling events primarily responsible for AAA formation remain uncertain. Caveolae are cholesterol-rich membrane microdomains that serve as a signaling platform to facilitate the temporal and spatial localization of signal transduction events including those stimulated by Ang II. Caveolin-1 (Cav1) enriched caveolae in vascular smooth muscle cells mediate ADAM17-dependent epidermal growth factor receptor (EGFR) transactivation, which is linked to vascular remodeling induced by Ang II. Here, we have tested our hypothesis that Cav1 plays a critical role for development of AAA at least in part via its specific alteration of Ang II signaling within caveolae. Cav1−/− mice and the control wild-type mice were co-infused with Ang II and β-aminopropionitrile to induce AAA. We found that Cav1−/− mice with the co-infusion did not develop AAA compared to control mice in spite of hypertension. We found an increased expression of ADAM17 and enhanced phosphorylation of EGFR in AAA. These events were markedly attenuated in Cav1−/− aortae with the co-infusion. Furthermore, Cav1−/− mice aortae with the co-infusion showed less endoplasmic reticulum stress, oxidative stress and inflammatory responses compared to aortae from control mice. Cav1 silencing in cultured vascular smooth muscle cells prevented Ang II-induced ADAM17 induction and activation. In conclusion, Cav1 appears to play a critical role in the formation of AAA and associated endoplasmic reticulum/oxidative stress presumably through the regulation of caveolae compartmentalized signals induced by Ang II. PMID:24329494

  12. Pyrogallol abates VSMC migration via modulation of Caveolin-1, matrix metalloproteinase and intima hyperplasia in carotid ligation mouse.

    PubMed

    Ma, Yu-Dong; Thiyagarajan, Varadharajan; Tsai, May-Jywan; Lue, Sheng-I; Chia, Yi-Chen; Shyue, Song-Kun; Weng, Ching-Feng

    2016-12-01

    Migration of vascular smooth muscle cells (VSMCs) contributes to intimal hyperplasia and other vascular diseases. Caveolin-1 (Cav-1) has been recognized as a proliferative inhibitor of VSMCs and is likely to be an important regulator of VSMC migration. The underlying mechanism of pyrogallol on the VSMC migration is not fully understood. This study attempted to dissect the role of Cav-1 and matrix metalloproteinase (MMP) in VSMC migration and to investigate the effect of pyrogallol on VSMC mobility during carotid artery ligation mice. The mRNA expression of MMP-3 and MMP-13 was down-regulated in cultured VSMC prepared from Cav-1-deficient (Cav-1 KO) mice whereas MMP-14 expression was up-regulated. Pyrogallol effectively inhibited the migration of Cav-1 KO VSMC by promoting the expression of tissue inhibitors of metalloproteinase (TIMP)-2. Pyrogallol also inhibited the migration of Cav-1 wild type (WT) VSMC, however, by increasing TIMP-1 expression and repressing MMP-2 activity. In a parallel in vivo study, intra-peritoneal (ip) of pyrogallol to carotid artery ligated mice significantly suppressed intima formation in mice carotid artery. Furthermore, the proMMP-9 activity in pyrogallol-treated mice serum significantly increased from Day 0 to Day 2 and decreased from Day 2 to Day 7 in a time-dependent manner. In addition, WT mice treated with pyrogallol had significantly reduced neointima formation, whereas no differences were observed in Cav-1 knock out (KO) mice. These results suggest that pyrogallol not only inhibited VSMC migration but also effectively diminishes the severity of neointima hyperplasia, implying that pyrogallol possesses potential anti-atherogenic effects for the treatment of vascular diseases.

  13. Caveolin-1 Deficiency Induces Spontaneous Endothelial-to-Mesenchymal Transition in Murine Pulmonary Endothelial Cells in Vitro

    PubMed Central

    Li, Zhaodong; Wermuth, Peter J.; Benn, Bryan S.; Lisanti, Michael P.; Jimenez, Sergio A.

    2014-01-01

    It was previously demonstrated that transforming growth factor β (TGF-β) induces endothelial-to-mesenchymal transition (EndoMT) in murine lung endothelial cells (ECs) in vitro. Owing to the important role of caveolin-1 (CAV1) in TGF-β receptor internalization and TGF-β signaling, the participation of CAV1 in the induction of EndoMT in murine lung ECs was investigated. Pulmonary ECs were isolated from wild-type and Cav1 knockout mice using immunomagnetic methods with sequential anti-CD31 and anti-CD102 antibody selection followed by in vitro culture and treatment with TGF-β1. EndoMT was assessed by semiquantitative RT-PCR for Acta2, Col1a1, Snai1, and Snai2; by immunofluorescence for α-smooth muscle actin; and by Western blot analysis for α-smooth muscle actin, SNAIL1, SNAIL2, and the α2 chain of type I collagen. The same studies were performed in Cav1−/− pulmonary ECs after restoration of functional CAV1 domains using a cell-permeable CAV1 scaffolding domain peptide. Pulmonary ECs from Cav1 knockout mice displayed high levels of spontaneous Acta2, Col1A, Snai1, and Snai2 expression, which increased after TGF-β treatment. Spontaneous and TGF-β1–stimulated EndoMT were abrogated by the restoration of functional CAV1 domains using a cell-permeable peptide. The findings suggest that CAV1 regulation of EndoMT may play a role in the development of fibroproliferative vasculopathies. PMID:23195429

  14. Effect of TNF-Alpha on Caveolin-1 Expression and Insulin Signaling During Adipocyte Differentiation and in Mature Adipocytes.

    PubMed

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Algarabel, Miriam; Ignacio Milagro, Fermín; Alfredo Martínez, J; de Miguel, Carlos

    2015-01-01

    Tumor necrosis factor-α (TNF-α)-mediated chronic low-grade inflammation of adipose tissue is associated with obesity and insulin resistance. Caveolin-1 (Cav-1) is the central component of adipocyte caveolae and has an essential role in the regulation of insulin signaling. The effects of TNF-α on Cav-1 expression and insulin signaling during adipocyte differentiation and in mature adipocytes were studied. 3T3-L1 cells were differentiated (21 days) in the presence TNF-α (10 ng/mL) and mature adipocytes were also treated with TNF-α for 48 hours. Cav-1 and insulin receptor (IR) gene methylation were determined as well as Cav-1, IR, PKB/AKT-2 and Glut-4 expression and activation by real time RT-PCR and western blot. Baseline and insulin-induced glucose uptake was measured by the 2-[C14]-deoxyglucose uptake assay. TNF-α slowed down the differentiation program, hindering the expression of some insulin signaling intermediates without fully eliminating insulin-mediated glucose uptake. In mature adipocytes, TNF-α did not compromise lipid-storage capacity, but downregulated the expression of the insulin signaling intermediates, totally blocking insulin-mediated glucose uptake. Insulin sensitivity correlated with the level of activated phospho-Cav-1 in both situations, strongly suggesting the direct contribution of Cav-1 to the maintenance of this physiological response. Cav-1 activation by phosphorylation seems to be essential for the maintenance of an active and insulin-sensitive glucose uptake. © 2015 S. Karger AG, Basel.

  15. Roles of Caveolin-1 in Angiotensin II-Induced Hypertrophy and Inward Remodeling of Cerebral Pial Arterioles.

    PubMed

    Umesalma, Shaikamjad; Houwen, Frederick Keith; Baumbach, Gary L; Chan, Siu-Lung

    2016-03-01

    Angiotensin II (Ang II) is a major determinant of inward remodeling and hypertrophy in pial arterioles that may have an important role in stroke during chronic hypertension. Previously, we found that epidermal growth factor receptor is critical in Ang II-mediated hypertrophy that may involve caveolin-1 (Cav-1). In this study, we examined the effects of Cav-1 and matrix metalloproteinase-9 (MMP9) on Ang II-mediated structural changes in pial arterioles. Cav-1-deficient (Cav-1(-/-)), MMP9-deficient (MMP9(-/-)), and wild-type mice were infused with either Ang II (1000 ng/kg per minute) or saline via osmotic minipumps for 28 days (n=6-8 per group). Systolic arterial pressure was measured by a tail-cuff method. Pressure and diameter of pial arterioles were measured through an open cranial window in anesthetized mice. Cross-sectional area of the wall was determined histologically in pressurized fixed pial arterioles. Expression of Cav-1, MMP9, phosphorylated epidermal growth factor receptor, and Akt was determined by Western blotting and immunohistochemistry. Deficiency of Cav-1 or MMP9 did not affect Ang II-induced hypertension. Ang II increased the expression of Cav-1, phosphorylated epidermal growth factor receptor, and Akt in wild-type mice, which was attenuated in Cav-1(-/-) mice. Ang II-induced hypertrophy, inward remodeling, and increased MMP9 expression in pial arterioles were prevented in Cav-1(-/-) mice. Ang II-mediated increases in MMP9 expression and inward remodeling, but not hypertrophy, were prevented in MMP9(-/-) mice. In conclusion, Cav-1 is essential in Ang II-mediated inward remodeling and hypertrophy in pial arterioles. Cav-1-induced MMP9 is exclusively involved in inward remodeling, not hypertrophy. Further studies are needed to determine the role of Akt in Ang II-mediated hypertrophy. © 2016 American Heart Association, Inc.

  16. A tumor suppressor role of the Bub3 spindle checkpoint protein after apoptosis inhibition

    PubMed Central

    Moutinho-Santos, Tatiana

    2013-01-01

    Most solid tumors contain aneuploid cells, indicating that the mitotic checkpoint is permissive to the proliferation of chromosomally aberrant cells. However, mutated or altered expression of mitotic checkpoint genes accounts for a minor proportion of human tumors. We describe a Drosophila melanogaster tumorigenesis model derived from knocking down spindle assembly checkpoint (SAC) genes and preventing apoptosis in wing imaginal discs. Bub3-deficient tumors that were also deficient in apoptosis displayed neoplastic growth, chromosomal aneuploidy, and high proliferative potential after transplantation into adult flies. Inducing aneuploidy by knocking down CENP-E and preventing apoptosis does not induce tumorigenesis, indicating that aneuploidy is not sufficient for hyperplasia. In this system, the aneuploidy caused by a deficient SAC is not driving tumorigenesis because preventing Bub3 from binding to the kinetochore does not cause hyperproliferation. Our data suggest that Bub3 has a nonkinetochore-dependent function that is consistent with its role as a tumor suppressor. PMID:23609535

  17. Identification of multi-copy suppressors for endoplasmic reticulum-mitochondria tethering proteins in Saccharomyces cerevisiae.

    PubMed

    Kojima, Rieko; Kajiura, Shu; Sesaki, Hiromi; Endo, Toshiya; Tamura, Yasushi

    2016-09-01

    In yeast, the endoplasmic reticulum (ER)-mitochondria encounter structure (ERMES) tethers the ER to mitochondria, but its primary function remains unclear. To gain insight into ERMES functions, we screened multi-copy suppressors of the growth-defective phenotype of mmm1∆ cells, which lack a core component of ERMES, and identified MCP1, MGA2, SPT23, and YGR250C (termed RIE1). Spt23 and Mga2 are homologous transcription factors known to activate transcription of the OLE1 gene, which encodes the fatty acid ∆9 desaturase. We found that Ole1 partially relieves the growth defects of ERMES-lacking cells, thus uncovering a relationship between fatty acid metabolism and ERMES functions. © 2016 Federation of European Biochemical Societies.

  18. Driver gene classification reveals a substantial overrepresentation of tumor suppressors among very large chromatin-regulating proteins

    PubMed Central

    Waks, Zeev; Weissbrod, Omer; Carmeli, Boaz; Norel, Raquel; Utro, Filippo; Goldschmidt, Yaara

    2016-01-01

    Compiling a comprehensive list of cancer driver genes is imperative for oncology diagnostics and drug development. While driver genes are typically discovered by analysis of tumor genomes, infrequently mutated driver genes often evade detection due to limited sample sizes. Here, we address sample size limitations by integrating tumor genomics data with a wide spectrum of gene-specific properties to search for rare drivers, functionally classify them, and detect features characteristic of driver genes. We show that our approach, CAnceR geNe similarity-based Annotator and Finder (CARNAF), enables detection of potentially novel drivers that eluded over a dozen pan-cancer/multi-tumor type studies. In particular, feature analysis reveals a highly concentrated pool of known and putative tumor suppressors among the <1% of genes that encode very large, chromatin-regulating proteins. Thus, our study highlights the need for deeper characterization of very large, epigenetic regulators in the context of cancer causality. PMID:28008934

  19. The effects of turmeric (curcumin) on tumor suppressor protein (p53) and estrogen receptor (ERα) in breast cancer cells

    PubMed Central

    Hallman, Kelly; Aleck, Katie; Dwyer, Brigitte; Lloyd, Victoria; Quigley, Meghan; Sitto, Nada; Siebert, Amy E; Dinda, Sumi

    2017-01-01

    Curcumin (CUR) is a compound that has antibacterial, antiviral, anti-inflammatory, and anticancer properties. In this study, we have analyzed the effects of CUR on the expression of ERα and p53 in the presence of hormones and anti-hormones in breast cancer cells. Cells were cultured in a medium containing charcoal-stripped fetal bovine serum to deplete any endogenous steroids and treated with CUR at varying concentrations or in combination with hormones and anti-hormones. Protein analysis revealed a relative decrease in the levels of p53 and ERα upon treatment with 5–60 µM CUR. In cell proliferation studies, CUR alone caused a 10-fold decrease compared with the treatment with estrogen, which suggests its antiproliferative effects. Delineating the role of CUR in the regulation of p53, ERα, and their mechanisms of action may be important in understanding the influence of CUR on tumor suppressors and hormone receptors in breast cancer. PMID:28331366

  20. Green tea catechin (−)-epicatechin gallate induces tumour suppressor protein ATF3 via EGR-1 activation

    PubMed Central

    Cho, Kyou-Nam; Sukhthankar, Mugdha; Lee, Seong-Ho; Yoon, Joo-Heon; Baek, Seung Joon

    2007-01-01

    Epicatechin gallate (ECG) is the third major catechin component in green tea, but it shows strong biological activity in some aspects, including apoptosis, cell growth inhibition, and membrane transport system in various cells. We previously reported that ECG induces activating transcription factor 3 (ATF3), which is involved in pro-apoptosis in HCT-116 cells. In this report, we present a molecular mechanism by which ECG induces ATF3 expression at the transcriptional level. We found that Sp3 contributed to the basal expression of the ATF3 gene, whereas EGR-1 played an important role in ECG-induced ATF3 expression in HCT-116 cells, as assessed by EMSA and co-transfection experiments. These results suggested that EGR-1, a tumour suppressor protein, could substantiate ECG’s role of ATF3 expression in human colorectal cancer cells. We also found that pro-oxidant activity of ECG contributed to ECG-induced ATF3 expression. PMID:17764926

  1. Driver gene classification reveals a substantial overrepresentation of tumor suppressors among very large chromatin-regulating proteins.

    PubMed

    Waks, Zeev; Weissbrod, Omer; Carmeli, Boaz; Norel, Raquel; Utro, Filippo; Goldschmidt, Yaara

    2016-12-23

    Compiling a comprehensive list of cancer driver genes is imperative for oncology diagnostics and drug development. While driver genes are typically discovered by analysis of tumor genomes, infrequently mutated driver genes often evade detection due to limited sample sizes. Here, we address sample size limitations by integrating tumor genomics data with a wide spectrum of gene-specific properties to search for rare drivers, functionally classify them, and detect features characteristic of driver genes. We show that our approach, CAnceR geNe similarity-based Annotator and Finder (CARNAF), enables detection of potentially novel drivers that eluded over a dozen pan-cancer/multi-tumor type studies. In particular, feature analysis reveals a highly concentrated pool of known and putative tumor suppressors among the <1% of genes that encode very large, chromatin-regulating proteins. Thus, our study highlights the need for deeper characterization of very large, epigenetic regulators in the context of cancer causality.

  2. Signal transduction in neurons: effects of cellular prion protein on fyn kinase and ERK1/2 kinase.

    PubMed

    Tomasi, Vittorio

    2010-12-16

    It has been reported that cellular prion protein (PrPc) co-localizes with caveolin-1 and participates to signal transduction events by recruiting Fyn kinase. As PrPc is a secreted protein anchored to the outer surface membrane through a glycosylphosphatidylinositol (GPI) anchor (secPrP) and caveolin-1 is located in the inner leaflet of plasma membrane, there is a problem of how the two proteins can physically interact each other and transduce signals. By using the GST-fusion proteins system we observed that PrPc strongly interacts with caveolin-1 scaffolding domain and with a caveolin-1 hydrophilic C-terminal region, but not with the caveolin-1 N-terminal region. In vitro binding experiments were also performed to define the site(s) of PrPc interacting with cav-1. The results are consistent with a participation of PrPc octapeptide repeats motif in the binding to caveolin-1 scaffolding domain. The caveolar localization of PrPc was ascertained by co-immunoprecipitation, by co-localization after flotation in density gradients and by confocal microscopy analysis of PrPc and caveolin-1 distributions in a neuronal cell line (GN11) expressing caveolin-1 at high levels. We observed that, after antibody-mediated cross-linking or copper treatment, PrPc was internalized probably into caveolae. We propose that following translocation from rafts to caveolae or caveolae-like domains, secPrP could interact with caveolin-1 and induce signal transduction events.

  3. Suppressors of a Host Range Mutation in the Rabbitpox Virus Serpin SPI-1 Map to Proteins Essential for Viral DNA Replication

    PubMed Central

    Luttge, Benjamin G.; Moyer, Richard W.

    2005-01-01

    The orthopoxvirus serpin SPI-1 is an intracellular serine protease inhibitor that is active against cathepsin G in vitro. Rabbitpox virus (RPV) mutants with deletions of the SPI-1 gene grow on monkey kidney cells (CV-1) but do not plaque on normally permissive human lung carcinoma cells (A549). This reduced-host-range (hr) phenotype suggests that SPI-1 may interact with cellular and/or other viral proteins. We devised a genetic screen for suppressors of SPI-1 hr mutations by first introducing a mutation into SPI-1 (T309R) at residue P14 of the serpin reactive center loop. The SPI-1 T309R serpin is inactive as a protease inhibitor in vitro. Introduction of the mutation into RPV leads to the same restricted hr phenotype as deletion of the SPI-1 gene. Second-site suppressors were selected by restoration of growth of the RPV SPI-1 T309R hr mutant on A549 cells. Both intragenic and extragenic suppressors of the T309R mutation were identified. One novel intragenic suppressor mutation, T309C, restored protease inhibition by SPI-1 in vitro. Extragenic suppressor mutations were mapped by a new procedure utilizing overlapping PCR products encompassing the entire genome in conjunction with marker rescue. One suppressor mutation, which also rendered the virus temperature sensitive for growth, mapped to the DNA polymerase gene (E9L). Several other suppressors mapped to gene D5R, an NTPase required for DNA replication. These results unexpectedly suggest that the host range function of SPI-1 may be associated with viral DNA replication by an as yet unknown mechanism. PMID:15994811

  4. Suppressors of a host range mutation in the rabbitpox virus serpin SPI-1 map to proteins essential for viral DNA replication.

    PubMed

    Luttge, Benjamin G; Moyer, Richard W

    2005-07-01

    The orthopoxvirus serpin SPI-1 is an intracellular serine protease inhibitor that is active against cathepsin G in vitro. Rabbitpox virus (RPV) mutants with deletions of the