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Sample records for organized smooth endoplasmic

  1. Birbeck granule-like "organized smooth endoplasmic reticulum" resulting from the expression of a cytoplasmic YFP-tagged langerin.

    PubMed

    Lenormand, Cédric; Spiegelhalter, Coralie; Cinquin, Bertrand; Bardin, Sabine; Bausinger, Huguette; Angénieux, Catherine; Eckly, Anita; Proamer, Fabienne; Wall, David; Lich, Ben; Tourne, Sylvie; Hanau, Daniel; Schwab, Yannick; Salamero, Jean; de la Salle, Henri

    2013-01-01

    Langerin is required for the biogenesis of Birbeck granules (BGs), the characteristic organelles of Langerhans cells. We previously used a Langerin-YFP fusion protein having a C-terminal luminal YFP tag to dynamically decipher the molecular and cellular processes which accompany the traffic of Langerin. In order to elucidate the interactions of Langerin with its trafficking effectors and their structural impact on the biogenesis of BGs, we generated a YFP-Langerin chimera with an N-terminal, cytosolic YFP tag. This latter fusion protein induced the formation of YFP-positive large puncta. Live cell imaging coupled to a fluorescence recovery after photobleaching approach showed that this coalescence of proteins in newly formed compartments was static. In contrast, the YFP-positive structures present in the pericentriolar region of cells expressing Langerin-YFP chimera, displayed fluorescent recovery characteristics compatible with active membrane exchanges. Using correlative light-electron microscopy we showed that the coalescent structures represented highly organized stacks of membranes with a pentalaminar architecture typical of BGs. Continuities between these organelles and the rough endoplasmic reticulum allowed us to identify the stacks of membranes as a form of "Organized Smooth Endoplasmic Reticulum" (OSER), with distinct molecular and physiological properties. The involvement of homotypic interactions between cytoplasmic YFP molecules was demonstrated using an A206K variant of YFP, which restored most of the Langerin traffic and BG characteristics observed in Langerhans cells. Mutation of the carbohydrate recognition domain also blocked the formation of OSER. Hence, a "double-lock" mechanism governs the behavior of YFP-Langerin, where asymmetric homodimerization of the YFP tag and homotypic interactions between the lectin domains of Langerin molecules participate in its retention and the subsequent formation of BG-like OSER. These observations confirm that

  2. A VAPB mutant linked to amyotrophic lateral sclerosis generates a novel form of organized smooth endoplasmic reticulum.

    PubMed

    Fasana, Elisa; Fossati, Matteo; Ruggiano, Annamaria; Brambillasca, Silvia; Hoogenraad, Casper C; Navone, Francesca; Francolini, Maura; Borgese, Nica

    2010-05-01

    VAPB (vesicle-associated membrane protein-associated protein B) is an endoplasmic reticulum (ER)-resident tail-anchored adaptor protein involved in lipid transport. A dominantly inherited mutant, P56S-VAPB, causes a familial form of amyotrophic lateral sclerosis (ALS) and forms poorly characterized inclusion bodies in cultured cells. To provide a cell biological basis for the understanding of mutant VAPB pathogenicity, we investigated its biogenesis and the inclusions that it generates. Translocation assays in cell-free systems and in cultured mammalian cells were used to investigate P56S-VAPB membrane insertion, and the inclusions were characterized by confocal imaging and electron microscopy. We found that mutant VAPB inserts post-translationally into ER membranes in a manner indistinguishable from the wild-type protein but that it rapidly clusters to form inclusions that remain continuous with the rest of the ER. Inclusions were induced by the mutant also when it was expressed at levels comparable to the endogenous wild-type protein. Ultrastructural analysis revealed that the inclusions represent a novel form of organized smooth ER (OSER) consisting in a limited number of parallel cisternae (usually 2 or 3) interleaved by a approximately 30 nm-thick electron-dense cytosolic layer. Our results demonstrate that the ALS-linked VAPB mutant causes dramatic ER restructuring that may underlie its pathogenicity in motoneurons.

  3. Interaction of the smooth endoplasmic reticulum and mitochondria.

    PubMed

    Goetz, J G; Nabi, I R

    2006-06-01

    The ER (endoplasmic reticulum) is composed of multiple domains including the nuclear envelope, ribosome-studded rough ER and the SER (smooth ER). The SER can also be functionally segregated into domains that regulate ER-Golgi traffic (transitional ER), ERAD (ER-associated degradation), sterol and lipid biosynthesis and calcium sequestration. The last two, as well as apoptosis, are critically regulated by the close association of the SER with mitochondria. Studies with AMFR (autocrine motility factor receptor) have defined an SER domain whose integrity and mitochondrial association can be modulated by ilimaquinone as well as by free cytosolic calcium levels in the normal physiological range. AMFR is an E3 ubiquitin ligase that targets its ligand directly to the SER via a caveolae/raft-dependent pathway. In the present review, we will address the relationship between the calcium-dependent morphology and mitochondrial association of the SER and its various functional roles in the cell.

  4. Interaction of the smooth endoplasmic reticulum and mitochondria.

    PubMed

    Goetz, J G; Nabi, I R

    2006-06-01

    The ER (endoplasmic reticulum) is composed of multiple domains including the nuclear envelope, ribosome-studded rough ER and the SER (smooth ER). The SER can also be functionally segregated into domains that regulate ER-Golgi traffic (transitional ER), ERAD (ER-associated degradation), sterol and lipid biosynthesis and calcium sequestration. The last two, as well as apoptosis, are critically regulated by the close association of the SER with mitochondria. Studies with AMFR (autocrine motility factor receptor) have defined an SER domain whose integrity and mitochondrial association can be modulated by ilimaquinone as well as by free cytosolic calcium levels in the normal physiological range. AMFR is an E3 ubiquitin ligase that targets its ligand directly to the SER via a caveolae/raft-dependent pathway. In the present review, we will address the relationship between the calcium-dependent morphology and mitochondrial association of the SER and its various functional roles in the cell. PMID:16709164

  5. Prognosis of oocytes showing aggregation of smooth endoplasmic reticulum.

    PubMed

    Ebner, Thomas; Moser, Marianne; Shebl, Omar; Sommerguber, Michael; Tews, Gernot

    2008-01-01

    Few cytoplasmic dysmorphisms of oocytes have been reported to negatively influence the further fate of the ova. One such anomaly, namely the central aggregation of the smooth endoplasmic reticulum (SER), has recently been associated with suboptimal outcome in a limited number of patients. In order to increase prognostic value, it was decided to prospectively screen all intracytoplasmic sperm injection patients within 1 year for eggs showing aggregations of SER. In addition, all deliveries (obstetric and neonatal data) were analysed. Occurrence of SER cluster was related to duration (P < 0.001) and dosage (P < 0.01) of the stimulation. Fertilization (58.9%) and blastulation rate (44.0%) were lower (P < 0.01) in affected ova compared with unaffected counterparts (77.4 and 87.8%, respectively). Pregnancies in women with affected gametes were accompanied by a higher incidence of obstetric problems (P < 0.01) leading to a non-significant trend towards earlier delivery and significantly reduced birthweight (P < 0.05). It is strongly recommended to avoid transfer of embryos/blastocysts derived from SER cluster-positive gametes. Patients have to be informed that even transfer of sibling oocytes without this anomaly involves a higher risk of detrimental outcome.

  6. Effect of praseodymium on drug metabolism in rat liver smooth and rough endoplasmic reticulum.

    PubMed

    Arvela, P; von Lehmann, B; Grajewski, O; Oberdisse, E

    1980-07-15

    A small i.v. dose (3 mg/kg) of a light lanthanon, praseodymium, impairs the drug metabolizing capacity of both the smooth and rough fractions of rat liver endoplasmic reticulum. This decrease in the activity of drug metabolizing enzymes and in the amount of cytochromes P-450 and b5 is more pronounced in the rough endoplasmic reticulum fraction.

  7. Cholesterol and steroid synthesizing smooth endoplasmic reticulum of adrenocortical cells contains high levels of proteins associated with the translocation channel.

    PubMed

    Black, Virginia H; Sanjay, Archana; van Leyen, Klaus; Lauring, Brett; Kreibich, Gert

    2005-10-01

    Steroid-secreting cells are characterized by abundant smooth endoplasmic reticulum whose membranes contain many enzymes involved in sterol and steroid synthesis. Yet they have relatively little morphologically identifiable rough endoplasmic reticulum, presumably required for synthesis and maintenance of the smooth membranes. In this study, we demonstrate that adrenal smooth microsomal subfractions enriched in smooth endoplasmic reticulum membranes contain high levels of translocation apparatus and oligosaccharyltransferase complex proteins, previously thought confined to rough endoplasmic reticulum. We further demonstrate that these smooth microsomal subfractions are capable of effecting cotranslational translocation, signal peptide cleavage, and N-glycosylation of newly synthesized polypeptides. This shifts the paradigm for distinction between smooth and rough endoplasmic reticulum. Confocal microscopy revealed the proteins to be distributed throughout the abundant tubular endoplasmic reticulum in these cells, which is predominantly smooth surfaced. We hypothesize that the broadly distributed translocon and oligosaccharyltransferase proteins participate in local synthesis and/or quality control of membrane proteins involved in cholesterol and steroid metabolism in a sterol-dependent and hormonally regulated manner.

  8. Infectious bronchitis virus 3a protein localizes to a novel domain of the smooth endoplasmic reticulum.

    PubMed

    Pendleton, Amanda R; Machamer, Carolyn E

    2005-05-01

    All coronaviruses possess small open reading frames (ORFs) between structural genes that have been hypothesized to play important roles in pathogenesis. Infectious bronchitis virus (IBV) ORF 3a is one such gene. It is highly conserved among group 3 coronaviruses, suggesting that it has an important function in infection. IBV 3a protein is expressed in infected cells but is not detected in virions. Sequence analysis predicted that IBV 3a was a membrane protein; however, only a fraction behaved like an integral membrane protein. Microscopy and immunoprecipitation studies demonstrated that IBV 3a localized to the cytoplasm in a diffuse pattern as well as in sharp puncta in both infected and transfected cells. These puncta did not overlap cellular organelles or other punctate structures. Confocal microscopy demonstrated that IBV 3a puncta lined up along smooth endoplasmic reticulum (ER) tubules and, in a significant number of instances, were partially surrounded by these tubules. Our results suggest that IBV 3a is partially targeted to a novel domain of the smooth ER.

  9. Organization of the cortical endoplasmic reticulum in the squid giant axon.

    PubMed

    Metuzals, J; Chang, D; Hammar, K; Reese, T S

    1997-08-01

    The organization of the cortical endoplasmic reticulum in the squid giant axon was investigated by rapid freeze and freeze-substitution electron microscopy, thereby eliminating the effects of fixatives on this potentially labile structure. Juvenile squid, which have thinner Schwann sheaths, were used in order to achieve freezing deep enough to include the entire axonal cortex. The smooth endoplasmic reticulum is composed of subaxolemmal and deeper cisternae, tubules, tethers and vesicles. The subaxolemmal cisternae make junctional contacts with the axolemma which are characterized by filamentous-granular bridging structures approximately 3 nm in diameter. The subaxolemmal junctions with the axolemma resemble the coupling junctions between the sarcoplasmic reticulum and the T-tubules in muscle. Reconstruction of short series of sections showed that a number of the elements of the endoplasmic reticulum were continuous but numerous separate vesicles were present as well. The morphology of endoplasmic reticulum as described here suggests that it is a highly dynamic entity as well as a Ca2+ sequestering organelle.

  10. Evidence for two isoforms of the endoplasmic-reticulum Ca2+ pump in pig smooth muscle.

    PubMed Central

    Eggermont, J A; Wuytack, F; De Jaegere, S; Nelles, L; Casteels, R

    1989-01-01

    cDNA clones coding for the endoplasmic reticulum Ca2+-transport ATPase have been cloned from a pig smooth-muscle cDNA library. The transcripts can be divided into two classes which differ in their 3' ends due to alternative splicing of the primary gene transcript. The class 1 cDNA encodes a protein of 997 amino acids (Mr 110,000). The class 2 protein (1042 amino acids; Mr 115,000) is completely identical to the class 1 protein except that the four C-terminal amino acids of the class 1 protein are replaced in the class 2 protein with a tail of 49 amino acids. Comparison of these sequences with other Ca2+ pump sequences reveals that the class 1 isoform corresponds to the sarcoplasmic reticulum Ca2+ pump of slow-twitch skeletal/cardiac muscle, whereas the class 2 protein corresponds to a Ca2+ pump recently detected in non-muscle tissues. PMID:2527496

  11. Distinct mechanisms controlling rough and smooth endoplasmic reticulum contacts with mitochondria.

    PubMed

    Wang, Peter T C; Garcin, Pierre O; Fu, Min; Masoudi, Matthew; St-Pierre, Pascal; Panté, Nelly; Nabi, Ivan R

    2015-08-01

    Gp78 (also known as AMFR), an endoplasmic-reticulum (ER)-associated protein degradation (ERAD) E3 ubiquitin ligase, localizes to mitochondria-associated ER and targets the mitofusin (Mfn1 and Mfn2) mitochondrial fusion proteins for degradation. Gp78 is also the cell surface receptor for autocrine motility factor (AMF), which prevents Gp78-dependent mitofusin degradation. Gp78 ubiquitin ligase activity promotes ER-mitochondria association and ER-mitochondria Ca(2+) coupling, processes that are reversed by AMF. Electron microscopy of HT-1080 fibrosarcoma cancer cells identified both smooth ER (SER; ∼8 nm) and wider (∼50-60 nm) rough ER (RER)-mitochondria contacts. Both short hairpin RNA (shRNA)-mediated knockdown of Gp78 (shGp78) and AMF treatment selectively reduced the extent of RER-mitochondria contacts without impacting on SER--mitochondria contacts. Concomitant small interfering RNA (siRNA)-mediated knockdown of Mfn1 increased SER-mitochondria contacts in both control and shGp78 cells, whereas knockdown of Mfn2 increased RER-mitochondria contacts selectively in shGp78 HT-1080 cells. The mitofusins therefore inhibit ER-mitochondria interaction. Regulation of close SER-mitochondria contacts by Mfn1 and of RER-mitochondria contacts by AMF-sensitive Gp78-mediated degradation of Mfn2 define new mechanisms that regulate ER-mitochondria interactions.

  12. Analyses of smooth endoplasmic reticulum of cerebellar parallel fibers in aging, ethanol-fed rats.

    PubMed

    Dlugos, Cynthia A

    2005-01-01

    The smooth endoplasmic reticulum (SER), a calcium storage organelle, is essential for normal neuronal function. Dilation of the SER is pathologic and a threat to neuronal calcium homeostasis. Dilation of the SER has been reported within the dendrites of cerebellar Purkinje neurons of aging rats after lengthy ethanol treatment. Ethanol-related alterations of parallel fiber SER have not been investigated despite the fact that such dilation may precede and contribute transsynaptically to SER dilation and degeneration in Purkinje neuron dendrites. Male Fischer 344 rats (n = 120; age = 12 months old) were randomly divided into three dietary groups (40 rats per group) and fed rat chow, the AIN-93M liquid control diet, or the AIN-93M liquid ethanol diet (without water) for 5, 10, 20, or 40 weeks (30 rats per time point). Sections from posterior vermal lobules were viewed with the electron microscope. Maximum and minimum diameters of parallel fiber SER profiles were measured. Ethanol-related dilation of parallel fiber SER was not found after 5, 10, 20, or 40 weeks of treatment. Age-related dilation of parallel fiber SER profiles did occur. These findings support the suggestions that (1) parallel fiber SER, unlike the SER in Purkinje neurons, is insensitive to ethanol and (2) the mechanisms by which ethanol and aging alter cerebellar function and structure are different.

  13. GFP-LC3 labels organised smooth endoplasmic reticulum membranes independently of autophagy.

    PubMed

    Korkhov, Vladimir M

    2009-05-01

    Disruption of autophagy leads to accumulation of intracellular multilamellar inclusions morphologically similar to organised smooth endoplasmic reticulum (OSER) membranes. However, the relation of these membranous compartments to autophagy is unknown. The purpose of this study was to test whether OSER plays a role in the autophagic protein degradation pathway. Here, GFP-LC3 is shown to localise to the OSER membranes induced by calnexin expression both in transiently transfected HEK293 cells and in mouse embryo fibroblasts. In contrast to GFP-LC3, endogenous LC3 is excluded from these membranes under normal conditions as well as after cell starvation. Furthermore, YFP-Atg5, a protein essential for autophagy and known to reside on autophagic membranes, is excluded from the calnexin-positive inclusion structures. In cells devoid of Atg5, a protein essential for autophagy and known to reside on autophagic membranes, colocalisation of calnexin with GFP-LC3 within the multilamellar bodies is preserved. I show that calnexin, a protein enriched in the OSER, is not subject to autophagic or lysosomal degradation. Finally, GFP-LC3 targeting to these membranes is independent of its processing and insensitive to drugs modulating autophagic and lysosomal protein degradation. These observations are inconsistent with a role of autophagic/lysosomal degradation in clearance of multilamellar bodies comprising OSER. Furthermore, GFP-LC3, a fusion protein widely used as a marker for autophagic vesicles and pre-autophagic compartments, may be trapped in this compartment and this artefact must be taken into account if the construct is used to visualise autophagic membranes.

  14. [Involvement of endoplasmic reticulum stress in solid organ transplantation].

    PubMed

    Pallet, Nicolas; Bouvier, Nicolas; Beaune, Philippe; Legendre, Christophe; Anglicheau, Dany; Thervet, Eric

    2010-04-01

    Endoplasmic reticulum (ER) stress is a situation caused by the accumulation of unfolded proteins in the endoplasmic reticulum, triggering an evolutionary conserved adaptive response termed the unfolded protein response. When adaptation fails, excessive and prolonged ER stress triggers cell suicide. Important roles for ER-initiated cell death pathways have been recognized for several diseases, including diabetes, hypoxia, ischemia/reperfusion injury, neurodegenerative and heart diseases. The implication of the ER stress is not well recognized in solid organ transplantation, but increasing evidence suggests its implication in mediating allograft injury. The purpose of this review is to summarize the mechanisms of ER stress and to discuss its implication during tissue injury in solid organ transplantation. The possible implications of the ER stress in the modifications of cell functional properties and phenotypic changes are also discussed beyond the scope of adaptation and cell death. Increasing the understanding of the cellular and molecular mechanisms of acute and chronic allograft damages could lead to the development of new biomarkers and to the discovery of new therapeutic strategies to prevent the initiation of graft dysfunction or to promote the tissue regeneration after injury. PMID:20412745

  15. Peroxynitrite resistance of sarco/endoplasmic reticulum Ca2+ pump in pig coronary artery endothelium and smooth muscle.

    PubMed

    Schmidt, Tracey; Zaib, Farhah; Samson, Sue E; Kwan, Chiu-Yin; Grover, Ashok K

    2004-07-01

    We examined the effects of peroxynitrite pre-treatment on sarco/endoplasmic reticulum Ca(2+) (SERCA) pump in pig coronary artery smooth muscle and endothelium. In saponin-permeabilized cells, smooth muscle showed much greater rates of the SERCA Ca(2+) pump-dependent (45)Ca(2+) uptake/mg protein than did the endothelial cells. Peroxynitrite treatment of cells inhibited the SERCA pump more severely in smooth muscle cells than in endothelial cells. To determine implications of this observation, we next examined the effect of the SERCA pump inhibitor cyclopiazonic acid (CPA) on intracellular Ca(2+) concentration of intact cultured cells. CPA produced cytosolic Ca(2+) transients in cultured endothelial and smooth muscle cells. Pre-treatment with peroxynitrite (200 microM) inhibited the Ca(2+) transients in the smooth muscle but not in the endothelial cells. CPA contracts de-endothelialized artery rings and relaxes precontracted arteries with intact endothelium. Peroxynitrite (250 microM) pre-treatment inhibited contraction in the de-endothelialized artery rings, but not the endothelium-dependent relaxation. Thus, endothelial cells appear to be more resistant than smooth muscle to the effects of peroxynitrite at the levels of SERCA pump activity, CPA-induced Ca(2+) transients in cultured cells, and the effects of CPA on contractility. The greater resistance of endothelium to peroxynitrite may play a protective role in pathological conditions such as ischemia-reperfusion when excess free radicals are produced.

  16. Bone morphogenetic protein-2 activates NADPH oxidase to increase endoplasmic reticulum stress and human coronary artery smooth muscle cell calcification.

    PubMed

    Liberman, Marcel; Johnson, Rebecca C; Handy, Diane E; Loscalzo, Joseph; Leopold, Jane A

    2011-09-30

    Bone morphogenetic protein-2 (BMP-2) increases oxidant stress and endoplasmic reticulum (ER) stress to stimulate differentiation of osteoblasts; however, the role of these signaling pathways in the transition of smooth muscle cells to a calcifying osteoblast-like phenotype remains incompletely characterized. We, therefore, treated human coronary artery smooth muscle cells (HCSMC) with BMP-2 (100ng/mL) and found an increase in NADPH oxidase activity and oxidant stress that occurred via activation of the bone morphogenetic protein receptor 2 and Smad 1 signaling. BMP-2-mediated oxidant stress also increased endoplasmic reticulum (ER) stress demonstrated by increased expression of GRP78, phospho-IRE1α, and the transcription factor XBP1. Analysis of a 1kb segment of the Runx2 promoter revealed an XBP1 binding site; electrophoretic mobility shift and chromatin immunoprecipitation assays demonstrated that XBP1 bound to the Runx2 promoter at this site in BMP-2-treated HCSMC. Inhibition of oxidant stress or ER stress decreased Runx2 expression, intracellular calcium deposition, and mineralization of BMP-2-treated HCSMC. Thus, in HCSMC, BMP-2 increases oxidant stress and ER stress to increase Runx2 expression and promote vascular smooth muscle cell calcification.

  17. Role of syntaxin 18 in the organization of endoplasmic reticulum subdomains.

    PubMed

    Iinuma, Takayuki; Aoki, Takehiro; Arasaki, Kohei; Hirose, Hidenori; Yamamoto, Akitsugu; Samata, Rie; Hauri, Hans-Peter; Arimitsu, Nagisa; Tagaya, Mitsuo; Tani, Katsuko

    2009-05-15

    The presence of subdomains in the endoplasmic reticulum (ER) enables this organelle to perform a variety of functions, yet the mechanisms underlying their organization are poorly understood. In the present study, we show that syntaxin 18, a SNAP (soluble NSF attachment protein) receptor localized in the ER, is important for the organization of two ER subdomains, smooth/rough ER membranes and ER exit sites. Knockdown of syntaxin 18 caused a global change in ER membrane architecture, leading to the segregation of the smooth and rough ER. Furthermore, the organization of ER exit sites was markedly changed concomitantly with dispersion of the ER-Golgi intermediate compartment and the Golgi complex. These morphological changes in the ER were substantially recovered by treatment of syntaxin-18-depleted cells with brefeldin A, a reagent that stimulates retrograde membrane flow to the ER. These results suggest that syntaxin 18 has an important role in ER subdomain organization by mediating the fusion of retrograde membrane carriers with the ER membrane.

  18. [Mechanisms of smooth endoplasmic reticulum aggregates creation in oocyte's cytoplasm in IVF cycles and its clinical relevance (literature review)].

    PubMed

    Kovalskaya, E V; Makarova, N P; Syrkasheva, A G; Dolgushina, N V; Kurilo, L F

    2015-01-01

    A large proportion of human oocytes received from exogenous gonadotropin-stimulated cycles have different morphological attributes, or dysmorphisms. The presence of dysmorphism can affect the fertilization rate, the embryo quality and subsequently the frequency of occurrence of implantation and pregnancy. Special attention is paid to oocytes with cytoplasmic attributes such as alteration of cytoplasmic granularity, the appearance of vacuoles, lipofuscin bodies and visible (large) aggregates of smooth endoplasmic reticulum. Endoplasmic reticulum (ER) is a type of the organelle forming an interconnected network of flattened, membrane-enclosed sacs or tubes. One of the main functions of ER in the oocyte is storage and redistribution of calcium, which provides cell activation during fertilization. Furthermore, complex of ER and mitochondria is necessary for accumulation of energy, synthesis of lipids and triglycerides, as well as synthesis of cytosolic and nuclear membranes during the early stages of cleavage. The appearance of anomalously large aggregates of ER in oocytes correlates with a low fertilization rate, low embryo quality, and pregnancy rate. The aim of the manuscript is to summarize current understanding of the mechanism of formation of such pathology of oocytes, together with special aspects of their fertilization and embryo quality.

  19. Reversible interactions between smooth domains of the endoplasmic reticulum and mitochondria are regulated by physiological cytosolic Ca2+ levels.

    PubMed

    Goetz, Jacky G; Genty, Hélène; St-Pierre, Pascal; Dang, Thao; Joshi, Bharat; Sauvé, Rémy; Vogl, Wayne; Nabi, Ivan R

    2007-10-15

    The 3F3A monoclonal antibody to autocrine motility factor receptor (AMFR) labels mitochondria-associated smooth endoplasmic reticulum (ER) tubules. siRNA down-regulation of AMFR expression reduces mitochondria-associated 3F3A labelling. The 3F3A-labelled ER domain does not overlap with reticulon-labelled ER tubules, the nuclear membrane or perinuclear ER markers and only partially overlaps with the translocon component Sec61alpha. Upon overexpression of FLAG-tagged AMFR, 3F3A labelling is mitochondria associated, excluded from the perinuclear ER and co-distributes with reticulon. 3F3A labelling therefore defines a distinct mitochondria-associated ER domain. Elevation of free cytosolic Ca(2+) levels with ionomycin promotes dissociation of 3F3A-labelled tubules from mitochondria and, judged by electron microscopy, disrupts close contacts (<50 nm) between smooth ER tubules and mitochondria. The ER tubule-mitochondria association is similarly disrupted upon thapsigargin-induced release of ER Ca(2+) stores or purinergic receptor stimulation by ATP. The inositol (1,4,5)-trisphosphate [Ins(1,4,5)P(3)] receptor (IP3R) colocalises to 3F3A-labelled mitochondria-associated ER tubules, and conditions that induce ER tubule-mitochondria dissociation disrupt continuity between 3F3A- and IP3R-labelled ER domains. RAS-transformed NIH-3T3 cells have increased basal cytosolic Ca(2+) levels and show dissociation of the 3F3A-labelled, but not IP3R-labelled, ER from mitochondria. Our data indicate that regulation of the ER-mitochondria association by free cytosolic Ca(2+) is a characteristic of smooth ER domains and that multiple mechanisms regulate the interaction between these organelles.

  20. Analysis of Ca(2+) uptake into the smooth endoplasmic reticulum of permeabilised sternal epithelial cells during the moulting cycle of the terrestrial isopod Porcellio scaber.

    PubMed

    Hagedorn, Monica; Ziegler, Andreas

    2002-07-01

    In terrestrial isopods, large amounts of Ca(2+) are transported across anterior sternal epithelial cells during moult-related deposition and resorption of CaCO(3) deposits. Because of its toxicity and function as a second messenger, resting cytosolic Ca(2+) levels must be maintained below critical concentrations during epithelial Ca(2+) transport, raising the possibility that organelles play a role during Ca(2+) transit. We therefore studied the uptake of Ca(2+) into Ca(2+)-sequestering organelles by monitoring the formation of birefringent calcium oxalate crystals in permeabilised anterior and posterior sternal epithelium cells of Porcellio scaber during Ca(2+)-transporting and non-transporting stages of the moulting cycle using polarised-light microscopy. The results indicate ATP-dependent uptake of Ca(2+) into organelles. Half-maximal crystal growth at a Ca(2+) activity, a(Ca), of 0.4 micromol l(-1) and blockade by cyclopiazonic acid suggest Ca(2+) uptake into the smooth endoplasmic reticulum by the smooth endoplasmic reticulum Ca(2+)-ATPase. Analytical electron microscopical techniques support this interpretation by revealing the accumulation of Ca(2+)-containing crystals in smooth membranous intracellular compartments. A comparison of different moulting stages demonstrated a virtual lack of crystal formation in the early premoult stage and a significant fivefold increase between mid premoult and the Ca(2+)-transporting stages of late premoult and intramoult. These results suggest a contribution of the smooth endoplasmic reticulum as a transient Ca(2+) store during intracellular Ca(2+) transit.

  1. Differential modulation of immunostimulant-triggered NO production by endoplasmic reticulum stress inducers in vascular smooth muscle cells.

    PubMed

    Ohta, Satoshi; Hattori, Yoshiyuki; Nakanishi, Nobuo; Sugimoto, Hiroyuki; Kasai, Kikuo

    2011-04-01

    We investigated the effects of endoplasmic reticulum (ER) stress inducers thapsigargin (TG) and tunicamycin (Tm) on immunostimulant lipopolysaccharide/interferon (LPS/IFN)-induced expression of isoform of nitric oxide synthase (iNOS) and nitric oxide (NO) production in vascular smooth muscle cells. LPS/IFN-induced iNOS mRNA expression was markedly enhanced by TG, whereas iNOS mRNA expression was strongly attenuated by Tm. Similarly, production of iNOS protein was markedly upregulated by TG but virtually eliminated by Tm. LPS/IFN-induced guanosine triphosphate cyclohydrolase I mRNA expression was slightly reduced by TG and markedly inhibited by Tm. Similarly, LPS/IFN-mediated induction of cellular biopterin was modestly reduced by TG and markedly inhibited by Tm. TG modestly enhanced LPS/IFN-induced activation of NF-κB, whereas Tm had no effect on it. Cellular respiration was reduced by TG and Tm in a concentration-dependent manner, which was confirmed by apoptosis assay. Thus, TG and Tm-induced ER stress and differently modulated NO production through alterations in iNOS expression and activity independently of NF-κB activation and caused a similar degree of ER stress-induced apoptosis.

  2. Endoplasmic reticulum is a key organella in bradykinin-triggered ATP release from cultured smooth muscle cells.

    PubMed

    Zhao, Yumei; Migita, Keisuke; Sato, Chiemi; Usune, Sadaharu; Iwamoto, Takahiro; Katsuragi, Takeshi

    2007-09-01

    ATP has broad functions as an autocrine/paracrine molecule. The mode of ATP release and its intracellular source, however, are little understood. Here we show that bradykinin via B(2)-receptor stimulation induces the extracellular release of ATP via the inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)]-signaling pathway in cultured taenia coli smooth muscle cells. It was found that bradykinin also increased the production of Ins(1,4,5)P(3) and 2-APB-inhibitable [Ca(2+)](i). The evoked release of ATP was suppressed by the Ca(2+)-channel blockers, nifedipine, and verapamil. Moreover, the extracellular release of ATP was elicited by photoliberation of Ins(1,4,5)P(3). Bradykinin caused a quick and transient accumulation of intracellular ATP from cells treated with 1% perchloric acid solution (PCA), but not with the cell lysis buffer. Peak accumulation was prevented by 2-APB and thapsigargin, but not by nifedipine or verapamil, inhibitors of extracellular release of ATP. These findings suggest that bradykinin elicits the extracellular release of ATP that is mediated by the Ins(1,4,5)P(3)-induced Ca(2+) signaling and, finally, leads to a Ca(2+)-dependent export of ATP from the cells. Furthermore, the bradykinin-induced transient accumulation of ATP in the cells treated with PCA may imply a possible release of ATP from the endoplasmic reticulum.

  3. Embryological outcomes in cycles with human oocytes containing large tubular smooth endoplasmic reticulum clusters after conventional in vitro fertilization.

    PubMed

    Itoi, Fumiaki; Asano, Yukiko; Shimizu, Masashi; Honnma, Hiroyuki; Murata, Yasutaka

    2016-01-01

    There have been no studies analyzing the effect of large aggregates of tubular smooth endoplasmic reticulum (aSERT) after conventional in vitro fertilization (cIVF). The aim of this study was to investigate whether aSERT can be identified after cIVF and the association between the embryological outcomes of oocytes in cycles with aSERT. This is a retrospective study examining embryological data from cIVF cycles showing the presence of aSERT in oocytes 5-6 h after cIVF. To evaluate embryo quality, cIVF cycles with at least one aSERT-metaphase II (MII) oocyte observed (cycles with aSERT) were compared to cycles with normal-MII oocytes (control cycles). Among the 4098 MII oocytes observed in 579 cycles, aSERT was detected in 100 MII oocytes in 51 cycles (8.8%). The fertilization rate, the rate of embryo development on day 3 and day 5-6 did not significantly differ between cycles with aSERT and control group. However, aSERT-MII oocytes had lower rates for both blastocysts and good quality blastocysts (p < 0.05). aSERT can be detected in the cytoplasm by removing the cumulus cell 5 h after cIVF. However, aSERT-MII oocytes do not affect other normal-MII oocytes in cycles with aSERT.

  4. Interferon-induced, antiviral human MxA protein localizes to a distinct subcompartment of the smooth endoplasmic reticulum.

    PubMed

    Stertz, Silke; Reichelt, Mike; Krijnse-Locker, Jacomine; Mackenzie, Jason; Simpson, Jeremy C; Haller, Otto; Kochs, Georg

    2006-09-01

    Human MxA protein belongs to the superfamily of dynamin-like large GTPases that are involved in intracellular membrane trafficking. MxA is induced by interferons-alpha/beta (IFN-alpha/beta) and is a key component of the antiviral response against RNA viruses. Here, we show that MxA localizes to membranes that are positive for specific markers of the smooth endoplasmic reticulum, such as Syntaxin17, but is excluded from other membrane compartments. Overexpression of MxA leads to a characteristic reorganization of the associated membranes. Interestingly, Hook3, mannose-6-phosphate receptor, and Lamp-1, which normally accumulate in cis- Golgi, endosomes, and lysosomes, respectively, also colocalized with MxA, indicating that these markers were redistributed to the MxA-positive compartment. Functional assays, however, did not show any effect of MxA on endocytosis or the secretory pathway. The present results demonstrate that MxA is an IFN-induced antiviral effector protein that resembles the constitutively expressed large GTPase family members in its capacity to localize to and reorganize intracellular membranes.

  5. Endoplasmic Reticulum Stress-Mediated Apoptosis Contributing to High Glucose-Induced Vascular Smooth Muscle Cell Calcification.

    PubMed

    Zhu, Qiang; Guo, Runmin; Liu, Chang; Fu, Duguan; Liu, Fuyuan; Hu, Jiefen; Jiang, Hong

    2015-01-01

    Vascular calcification (VC) is a common feature in patients with type 2 diabetes mellitus, a metabolic disorder that is characterized by hyperglycemia (high blood glucose) in the context of insulin resistance and a relative lack of insulin. Recently, a few studies have indicated that a high concentration of glucose amplifies the osteogenesis of vascular smooth muscle cells (VSMCs). Some previous reports state that endoplasmic reticulum (ER) stress-mediated apoptosis was activated in and contributed to VC. However, whether or not high glucose could induce ER stress-mediated apoptosis and then involve the pathogenesis of VC remains unclear. The purpose of the present study was to investigate whether high blood glucose-induced VC in diabetes mellitus is caused by the ER response and subsequent apoptosis. We examined the effects of high glucose on the ER stress response of VSMCs. High glucose treatment drastically increased the ER stress response in VSMCs. The high glucose-induced osteoblastic differentiation of VSMCs was significantly attenuated by pretreatment with 500 μM of 4-PBA (an ER stress inhibitor) prior to the exposure to high glucose, as evidenced by decreases in the expression of Runx2 and activity of alkaline phosphatase, as well as calcium nodules. These results suggest that high glucose induces the ER stress response and apoptosis, leading to high glucose-elicited VC.

  6. GLP-1 promotes mitochondrial metabolism in vascular smooth muscle cells by enhancing endoplasmic reticulum-mitochondria coupling.

    PubMed

    Morales, Pablo E; Torres, Gloria; Sotomayor-Flores, Cristian; Peña-Oyarzún, Daniel; Rivera-Mejías, Pablo; Paredes, Felipe; Chiong, Mario

    2014-03-28

    Incretin GLP-1 has important metabolic effects on several tissues, mainly through the regulation of glucose uptake and usage. One mechanism for increasing cell metabolism is modulating endoplasmic reticulum (ER)-mitochondria communication, as it allows for a more efficient transfer of Ca(2+) into the mitochondria, thereby increasing activity. Control of glucose metabolism is essential for proper vascular smooth muscle cell (VSMC) function. GLP-1 has been shown to produce varied metabolic actions, but whether it regulates glucose metabolism in VSMC remains unknown. In this report, we show that GLP-1 increases mitochondrial activity in the aortic cell line A7r5 by increasing ER-mitochondria coupling. GLP-1 increases intracellular glucose and diminishes glucose uptake without altering glycogen content. ATP, mitochondrial potential and oxygen consumption increase at 3h of GLP-1 treatment, paralleled by increased Ca(2+) transfer from the ER to the mitochondria. Furthermore, GLP-1 increases levels of Mitofusin-2 (Mfn2), an ER-mitochondria tethering protein, via a PKA-dependent mechanism. Accordingly, PKA inhibition and Mfn2 down-regulation prevented mitochondrial Ca(2+) increases in GLP-1 treated cells. Inhibiting both Ca(2+) release from the ER and Ca(2+) entry into mitochondria as well as diminishing Mfn2 levels blunted the increase in mitochondrial activity in response to GLP-1. Altogether, these results strongly suggest that GLP-1 increases ER-mitochondria communication in VSMC, resulting in higher mitochondrial activity.

  7. Endoplasmic Reticulum Stress-Mediated Apoptosis Contributing to High Glucose-Induced Vascular Smooth Muscle Cell Calcification.

    PubMed

    Zhu, Qiang; Guo, Runmin; Liu, Chang; Fu, Duguan; Liu, Fuyuan; Hu, Jiefen; Jiang, Hong

    2015-01-01

    Vascular calcification (VC) is a common feature in patients with type 2 diabetes mellitus, a metabolic disorder that is characterized by hyperglycemia (high blood glucose) in the context of insulin resistance and a relative lack of insulin. Recently, a few studies have indicated that a high concentration of glucose amplifies the osteogenesis of vascular smooth muscle cells (VSMCs). Some previous reports state that endoplasmic reticulum (ER) stress-mediated apoptosis was activated in and contributed to VC. However, whether or not high glucose could induce ER stress-mediated apoptosis and then involve the pathogenesis of VC remains unclear. The purpose of the present study was to investigate whether high blood glucose-induced VC in diabetes mellitus is caused by the ER response and subsequent apoptosis. We examined the effects of high glucose on the ER stress response of VSMCs. High glucose treatment drastically increased the ER stress response in VSMCs. The high glucose-induced osteoblastic differentiation of VSMCs was significantly attenuated by pretreatment with 500 μM of 4-PBA (an ER stress inhibitor) prior to the exposure to high glucose, as evidenced by decreases in the expression of Runx2 and activity of alkaline phosphatase, as well as calcium nodules. These results suggest that high glucose induces the ER stress response and apoptosis, leading to high glucose-elicited VC. PMID:26890314

  8. GLP-1 promotes mitochondrial metabolism in vascular smooth muscle cells by enhancing endoplasmic reticulum-mitochondria coupling.

    PubMed

    Morales, Pablo E; Torres, Gloria; Sotomayor-Flores, Cristian; Peña-Oyarzún, Daniel; Rivera-Mejías, Pablo; Paredes, Felipe; Chiong, Mario

    2014-03-28

    Incretin GLP-1 has important metabolic effects on several tissues, mainly through the regulation of glucose uptake and usage. One mechanism for increasing cell metabolism is modulating endoplasmic reticulum (ER)-mitochondria communication, as it allows for a more efficient transfer of Ca(2+) into the mitochondria, thereby increasing activity. Control of glucose metabolism is essential for proper vascular smooth muscle cell (VSMC) function. GLP-1 has been shown to produce varied metabolic actions, but whether it regulates glucose metabolism in VSMC remains unknown. In this report, we show that GLP-1 increases mitochondrial activity in the aortic cell line A7r5 by increasing ER-mitochondria coupling. GLP-1 increases intracellular glucose and diminishes glucose uptake without altering glycogen content. ATP, mitochondrial potential and oxygen consumption increase at 3h of GLP-1 treatment, paralleled by increased Ca(2+) transfer from the ER to the mitochondria. Furthermore, GLP-1 increases levels of Mitofusin-2 (Mfn2), an ER-mitochondria tethering protein, via a PKA-dependent mechanism. Accordingly, PKA inhibition and Mfn2 down-regulation prevented mitochondrial Ca(2+) increases in GLP-1 treated cells. Inhibiting both Ca(2+) release from the ER and Ca(2+) entry into mitochondria as well as diminishing Mfn2 levels blunted the increase in mitochondrial activity in response to GLP-1. Altogether, these results strongly suggest that GLP-1 increases ER-mitochondria communication in VSMC, resulting in higher mitochondrial activity. PMID:24613839

  9. Acetylation in vitro of constituent polypeptides by smooth endoplasmic reticulum (SER) and Golgi membrane fractions

    SciTech Connect

    Sambasivam, H.; Murray, R.K.

    1986-05-01

    Many polypeptides of the membranes of the ER are phosphorylated. To determine if any such polypeptides are acetylated, microsomal and other classical subcellular fractions were incubated with (/sup 3/H) acetyl-CoA; the specific activity of the microsomal fraction (MF) was the greatest. SDS-PAGE revealed that some 20 polypeptides of the MF were acetylated; 2-D electrophoretograms extended this number to approximately 60. Separation of the MF into smooth (S) and rough (R) fractions showed that the great majority of the labelled polypeptides belonged to the former. Isolation of a Golgi fraction revealed that its acetylation activity was approximately 3-fold greater than the SER fraction. Extensive proteolytic digestion of the MF followed by radiochromatography disclosed some 9 components whose precise nature (acetylated amino acids and/or sialic acids, etc.) is under study. Assuming that the majority of the radioactivity is in the former components and that a similar process occurs in vivo, the authors suggest that the Golgi apparatus may be a major site of acetylation of membrane and possibly other proteins.

  10. Endoplasmic reticulum stress stimulates heme oxygenase-1 gene expression in vascular smooth muscle. Role in cell survival.

    PubMed

    Liu, Xiao-ming; Peyton, Kelly J; Ensenat, Diana; Wang, Hong; Schafer, Andrew I; Alam, Jawed; Durante, William

    2005-01-14

    Heme oxygenase-1 (HO-1) is a cytoprotective protein that catalyzes the degradation of heme to biliverdin, iron, and carbon monoxide (CO). In the present study, we found that endoplasmic reticulum (ER) stress induced by a variety of experimental agents stimulated a time- and concentration-dependent increase in HO-1 mRNA and protein in vascular smooth muscle cells (SMC). The induction of HO-1 by ER stress was blocked by actinomycin D or cycloheximide and was independent of any changes in HO-1 mRNA stability. Luciferase reporter assays indicated that ER stress stimulated HO-1 promoter activity via the antioxidant response element. Moreover, ER stress induced the nuclear import of Nrf2 and the binding of Nrf2 to the HO-1 antioxidant response element. Interestingly, ER stress stimulated SMC apoptosis, as demonstrated by annexin V binding, caspase-3 activation, and DNA laddering. The induction of apoptosis by ER stress was potentiated by HO inhibition, whereas it was prevented by addition of HO substrate. In addition, exposure of SMC to exogenously administered CO inhibited ER stress-mediated apoptosis, and this was associated with a decrease in the expression of the proapoptotic protein, GADD153. In contrast, the other HO-1 products failed to block apoptosis or GADD153 expression during ER stress. These results demonstrated that ER stress is an inducer of HO-1 gene expression in vascular SMC and that HO-1-derived CO acts in an autocrine fashion to inhibit SMC apoptosis. The capacity of ER stress to stimulate the HO-1/CO system provides a novel mechanism by which this organelle regulates cell survival.

  11. Smooth endoplasmic reticulum dilation and degeneration in Purkinje neuron dendrites of aging ethanol-fed female rats.

    PubMed

    Dlugos, Cynthia A

    2006-01-01

    The effects of chronic ethanol consumption on the extensive Purkinje neuron (PN) dendritic arbor of male rats include dilation of the smooth endoplasmic reticulum (SER) and dendritic regression. The purpose of the present study was to examine the molecular layer of female rats for the presence of ethanol-related SER dilation and evidence of degeneration within the PN dendritic arbor. Twenty-one 12-month-old Fischer 344 female rats (n = 7/treatment group) received a liquid ethanol, liquid control, or rat chow diet for a period of 40 weeks. Ethanol-fed rats received 35% of their dietary calories as ethanol. Pair-fed rats received a liquid control diet that was isocaloric to the ethanol diet. Chow-fed rats received standard laboratory rat chow ad libitum. At the end of treatment, tissues from the anterior and posterior lobes of the cerebellar vermis were viewed and photographed with the electron microscope. The diameters of SER profiles were measured and the density of degenerating bodies within the PN dendritic arbor was quantitated. In the posterior lobe, ethanol-related SER dilation was apparent. In the anterior lobe, the density of degenerating bodies within PN dendritic shafts was significantly increased but SER dilation in PN dendritic shafts was absent. These results confirm that SER dilation and dendritic degeneration in PN dendrites may precede and contribute to ethanol-related regression in female rats. In addition, comparison of these results with data obtained in male rats from a previous study suggests that PN dendrites in females may be more sensitive to the effects of ethanol.

  12. Subcellular calcium localization and AT0-dependent Ca2+-uptake by smooth endoplasmic reticulum in an invertebrate photoreceptor cell. An ultrastrucutral, cytochemical and X-ray microanalytical study.

    PubMed

    Walz, B

    1979-10-01

    In Hirudo medicinalis an extensive and highly elaborate three dimensional network of smooth endoplasmic reticulum cisternae is found in very close structural relationship to the receptive (microvillar) membrane, as reported for many other invertebrates. A variant of the potassium pyroantimonate technique showed that these submicrovillar endoplasmic reticulum cisternae (SMC) and mitochondria are major intracellular calcium stores. Furthermore, using saponine-skinned photoreceptors for an in situ accumulation experiment, calcium oxalate precipitates in SMC demonstrate that this organelle is able to accumulate Ca2+ from a concentration of 2 x 10(-5) M, when ATP, Mg2+, and oxalate ions are present in the accumulation medium. This result provides direct evidence for the hypothesis that SMC may play a particularly important role in the regulation of intracellular ionized calcium in invertebrate photoreceptor cells. Morphological evidence supports this view. PMID:160317

  13. Comparative toxicology of tetrachlorobiphenyls in mink and rats. I. Changes in hepatic enzyme activity and smooth endoplasmic reticulum volume

    SciTech Connect

    Gillette, D.M.; Corey, R.D.; Helferich, W.G.; McFarland, J.M.; Lowenstine, L.J.; Moody, D.E.; Hammock, B.D.; Shull, L.R.

    1987-01-01

    Mink have been shown previously to be extraordinarily sensitive to polychlorinated biphenyls (PCBs) and related classes of halogenated hydrocarbons. This study explored several aspects of the acute response of mink to two purified tetrachlorobiphenyl (TCB) congeners and compared their response with that of the rat, a less sensitive and more thoroughly studied species. Young female pastel mink and young female Sprague-Dawley rats received three daily intraperitoneal injections with equimolar doses of either 2,4,2',4'-TCB or 3,4,3',4'-TCB, and were sacrificed after 7 days. Two control groups were used for each species; one was allowed free access to food and the other was pair-fed to the 3,4,3',4'-TCB treatment group. Rats remained clinically normal, while mink treated with 3,4,3',4'-TCB developed severe anorexia, diarrhea, and melena. Both species had significant increases in hepatic cytochrome P-450 content and the characteristic shift in the spectral maxima from 450 to 448 nm in the 3,4,3',4'-TCB- but not in the 2,4,2',4'-TCB-treated animals. Rats but not mink had increased activities of several hepatic monooxygenases in response to both congeners while microsomal epoxide hydrolase was increased in rats after 2,4,2',4'-TCB and in mink after 3,4,3',4'-TCB. Significant increases in the relative volume of smooth endoplasmic reticulum within hepatocytes of 2,4,2',4'-TCB-treated rats but not mink were confirmed by ultrastructural morphometry. Accumulation of both congeners was greater in adipose tissue than in the liver of either species. In both species, concentrations in adipose tissue were much greater for 2,4,2',4'-TCB than for 3,4,3',4'-TCB. PCB toxicosis in mink, as in other species, appeared to be dependent on isomeric arrangement of chlorine substituents. However, unlike other species, the toxicosis was not associated with biochemical or morphological evidence of hepatic enzyme induction.

  14. Functional linkage of Na+-Ca2+-exchanger to sarco/endoplasmic reticulum Ca2+ pump in coronary artery: comparison of smooth muscle and endothelial cells.

    PubMed

    Davis, Kim A; Samson, Sue E; Hammel, Kaitlin E; Kiss, Lorand; Fulop, Ferenc; Grover, Ashok K

    2009-08-01

    An increase in cytosolic Ca(2+) concentration in coronary artery smooth muscle causes a contraction but in endothelium it causes relaxation. Na(+)-Ca(2+)-exchanger (NCX) may play a role in Ca(2+) dynamics in both the cell types. Here, the NCX-mediated (45)Ca(2+) uptake was compared in Na(+)-loaded pig coronary artery smooth muscle and endothelial cells. In both the cell types, this uptake was inhibited by KB-R7943, SEA 0400 and by monensin, but not by cariporide. Prior loading of the cells with the Ca(2+) chelator BAPTA increased the NCX-mediated (45)Ca(2+) uptake in smooth muscle but not in endothelial cells. In the presence or absence of BAPTA loading, the Na(+)-mediated (45)Ca(2+) uptake was greater in endothelial than in smooth muscle cells. In smooth muscle cells without BAPTA loading, thapsigargin diminished the NCX-mediated (45)Ca(2+) entry. This effect was not observed in endothelial cells or in either cell type after BAPTA loading. The results in the smooth muscle cells are consistent with a limited diffusional space model in which the NCX-mediated (45)Ca(2+) uptake was enhanced by chelation of cytosolic Ca(2+) or by its sequestration by the sarco/endoplasmic reticulum Ca(2+) pump (SERCA). They suggest a functional linkage between NCX and SERCA in the smooth muscle but not in the endothelial cells. The concept of a linkage between NCX and SERCA in smooth muscle was also confirmed by similar distribution of NCX and SERCA2 proteins when detergent-treated microsomes were fractionated by flotation on sucrose density gradients. Thus, the coronary artery smooth muscle and endothelial cells differ not only in the relative activities of NCX but also in its functional linkage to SERCA.

  15. Molecular characterisation of the smooth endoplasmic reticulum Ca(2+)-ATPase of Porcellio scaber and its expression in sternal epithelia during the moult cycle.

    PubMed

    Hagedorn, Monica; Weihrauch, Dirk; Towle, David W; Ziegler, Andreas

    2003-07-01

    The anterior sternal epithelial cells of the terrestrial isopod Porcellio scaber transport large amounts of calcium during the formation and resorption of intermittent calcium carbonate deposits. Recent investigations on epithelia involved in mineralisation processes suggest a role of the smooth endoplasmic reticulum Ca(2+)-ATPase (SERCA) in transcellular calcium transport. We present the first molecular characterisation of a SERCA within a crustacean mineralising epithelium. We cloned the SERCA from a cDNA library of the anterior sternal epithelium and used in situ hybridisation to compare the expression of the SERCA mRNA between three different moulting stages. The full-length SERCA cDNA has an open reading frame of 3006 nucleotides. The deduced 1002 amino-acid polypeptide has a predicted molecular mass of 109.7 kDa and 87% identity to the SERCA of Procambarus clarkii axial muscle isoform. In situ hybridisation confirmed expression within the anterior sternal epithelium and revealed an increase in SERCA mRNA abundance from the non-transporting, early premoult stage to the calcium transporting, late premoult and intramoult stage. The results support previous indications of a contribution by the smooth endoplasmic reticulum to transcellular calcium transport and suggest a transcriptional regulation of SERCA activity.

  16. Hepatic glycogen synthesis in the fetal mouse: An ultrastructural, morphometric, and autoradiographic investigation of the relationship between the smooth endoplasmic reticulum and glycogen

    SciTech Connect

    Breslin, J.S.

    1989-01-01

    Fetal rodent hepatocytes undergo a rapid and significant accumulation of glycogen prior to birth. The distinct association of the smooth endoplasmic reticulum (SER) with glycogen during glycogen synthesis documented in the adult hepatocyte has not been clearly demonstrated in the fetus. The experiments described in this dissertation tested the hypothesis that SER is present and functions in the synthesis of fetal hepatic glycogen. Biochemical analysis, light microscopic (LM) histochemistry and electron microscope (EM) morphometry demonstrated that fetal hepatic glycogen synthesis began on day 15, with maximum accumulation occurring between days 17-19. Glycogen accumulation began in a small population of cells. Both the number of cells containing glycogen and the quantity of glycogen per cell increased as glycogen accumulated. Smooth endoplasmic reticulum (SER) was observed on day 14 of gestation and throughout fetal hepatic glycogen synthesis, primarily as dilated ribosome-free terminal extensions of rough endoplasmic reticulum (RER), frequently associated with glycogen. SER was in close proximity to isolated particles of glycogen and at the periphery of large compact glycogen deposits. Morphometry demonstrated that the membrane surface of SER in the average fetal hepatocyte increased as glycogen accumulated through day 18 and dropped significantly as glycogen levels peaked on day 19. Parallel alterations in RER membrane surface, indicated overall increases in ER membrane surface. Autoradiography following administration of {sup 3}H-galactose demonstrated that newly synthesized glycogen was deposited near profiles of SER at day 16 and at day 18; however, at day 18 the majority of label was uniformly distributed over glycogen remote from profiles of SER.

  17. Mitofusin-2-mediated tethering of mitochondria and endoplasmic reticulum promotes cell cycle arrest of vascular smooth muscle cells in G0/G1 phase.

    PubMed

    Li, Dan; Li, Xiaolan; Guan, Yang; Guo, Xiaomei

    2015-06-01

    Mitofusin-2 (Mfn-2) is a hyperplasia suppressor. Changes in Mfn-2 expression are thought to reflect mitochondrial remodeling during cell proliferation. However, it is unclear how the participation of Mfn-2 in mitochondrial remodeling prevents cellular proliferation. Here we show that arresting vascular smooth muscle cells (VSMCs) in the G0/G1 phase by serum starvation up-regulates Mfn-2 expression and causes mitochondria to assemble into a tubular network and to attach to the endoplasmic reticulum (ER). In the S phase, short rod-shaped mitochondrial structures that were dissociated from the ER were observed. Levels of glucose, ATP, l-amino acid, and NADP(+) did not vary throughout the cell cycle. However, NAD(+) level was lower and NADH level was higher in the G0/G1 phase than in the S phase. Mitochondrial membrane potential was lower in the S phase than in the G0/G1 phase. Infecting VSMCs with an adenovirus encoding full-length Mfn-2 increased NADH level and reduced NAD(+) level, while infecting the cells with an adenovirus that silences the p21(ras) signature motif produced opposite effects. These results suggest that Mfn-2 up-regulation causes mitochondrial fusion into tubular networks and attachment to the ER, which in turn halts proliferation of VSMCs.

  18. Male Sprague-Dawley rats exposed to in utero di(n-butyl) phthalate: dose dependent and age-related morphological changes in Leydig cell smooth endoplasmic reticulum.

    PubMed

    Shirai, Masaru; Wakui, Shin; Wempe, Michael F; Mutou, Tomoko; Oyama, Noriko; Motohashi, Masaya; Takahashi, Hiroyuki; Kansaku, Norio; Asari, Masao; Hano, Hiroshi; Endou, Hitoshi

    2013-01-01

    When 100 mg/kg/day of di(n-butyl) phthalate (DBP) was intragastrically administered to pregnant Sprague-Dawley rats throughout gestation days 12 to 21, the male pups had similar body weights with no apparent physical differences (e.g., litter size, sex ratio) compared to that of the vehicle group. However, prominent age-related morphological alterations in the smooth endoplasmic reticulum (sER) of testicular Leydig cells (LCs) were observed once these animals reached puberty. At weeks 5 to 7, the abundant sER with non-dilated cisternae was distributed in LCs. Subsequently, although the number of LCs significantly increased, the amount of sER was significantly decreased at 9 to 14 weeks of age and had disappeared at 17 weeks. In contrast, the number of LCs and the amount of sER in LCs of the lower dose groups (10, 30, and 50 mg/kg/day) were similar to those of the vehicle group. Further, serum testosterone levels in the 100 mg/kg dose group were significantly lower during 5 to 17 weeks of age. While their luteinizing hormone (LH) level was significantly lower at 5 to 7 weeks of age, it became significantly higher during 9 to 17 weeks. The amount of sER in LCs decreased with age with the increase in LCs proliferation and serum LH levels in rat exposed in utero to DBP in a dose-dependent manner.

  19. Proximity of Na+ -Ca2+ -exchanger and sarco/endoplasmic reticulum Ca2+ pump in pig coronary artery smooth muscle: fluorescence microscopy.

    PubMed

    Kuszczak, Iwona; Kuner, Rajneet; Samson, Sue E; Grover, Ashok K

    2010-06-01

    Pig coronary artery smooth muscle expresses the Na(+)-Ca(2+)-exchanger NCX1 and the sarco/endoplasmic reticulum (SER) Ca(2+) pump SERCA2. NCX has been proposed to play a role in refilling the SER Ca(2+) pool. Caveolae may also direct Ca(2+) traffic during cell signaling. Here, we use immunofluorescence microscopy to determine if there is proximity between NCX1, SERCA2, and the caveolar protein caveolin-1. Stacks of images of cell surface domains were analyzed. Image stacks for one protein were analyzed for overlap with another protein, with and without randomization or image shifting. Within the resolution of light microscopy, there is significant overlap in the distributions of NCX1, SERCA2, and caveolin-1 but the three proteins are not always co-localized. The proximity between NCX1, SERCA2 is consistent with the assertion that NCX may supply Ca(2+) for refilling the SER but this relationship is only partial. Similarly, caveolae may direct traffic in some Ca(2+) signaling pathways but not others.

  20. Interaction between endoplasmic/sarcoplasmic reticulum stress (ER/SR stress), mitochondrial signaling and Ca(2+) regulation in airway smooth muscle (ASM).

    PubMed

    Delmotte, Philippe; Sieck, Gary C

    2015-02-01

    Airway inflammation is a key aspect of diseases such as asthma. Several inflammatory cytokines (e.g., TNFα and IL-13) increase cytosolic Ca(2+) ([Ca(2+)]cyt) responses to agonist stimulation and Ca(2+) sensitivity of force generation, thereby enhancing airway smooth muscle (ASM) contractility (hyper-reactive state). Inflammation also induces ASM proliferation and remodeling (synthetic state). In normal ASM, the transient elevation of [Ca(2+)]cyt induced by agonists leads to a transient increase in mitochondrial Ca(2+) ([Ca(2+)]mito) that may be important in matching ATP production with ATP consumption. In human ASM (hASM) exposed to TNFα and IL-13, the transient increase in [Ca(2+)]mito is blunted despite enhanced [Ca(2+)]cyt responses. We also found that TNFα and IL-13 induce reactive oxidant species (ROS) formation and endoplasmic/sarcoplasmic reticulum (ER/SR) stress (unfolded protein response) in hASM. ER/SR stress in hASM is associated with disruption of mitochondrial coupling with the ER/SR membrane, which relates to reduced mitofusin 2 (Mfn2) expression. Thus, in hASM it appears that TNFα and IL-13 result in ROS formation leading to ER/SR stress, reduced Mfn2 expression, disruption of mitochondrion-ER/SR coupling, decreased mitochondrial Ca(2+) buffering, mitochondrial fragmentation, and increased cell proliferation.

  1. Phospholipase Cbeta3 is distributed in both somatodendritic and axonal compartments and localized around perisynapse and smooth endoplasmic reticulum in mouse Purkinje cell subsets.

    PubMed

    Nomura, Sachi; Fukaya, Masahiro; Tsujioka, Takao; Wu, Dianqing; Watanabe, Masahiko

    2007-02-01

    Phospholipase Cbeta3 (PLCbeta3) and PLCbeta4 are the two major isoforms in cerebellar Purkinje cells (PCs), displaying reciprocal expression across the cerebellum. Here, we examined subcellular distribution of PLCbeta3 in the mouse cerebellum by producing specific antibody. PLCbeta3 was detected as a particulate pattern of immunostaining in various PC elements. Like PLCbeta4, PLCbeta3 was richly distributed in somatodendritic compartments, where it was colocalized with molecules constituting the metabotropic glutamate receptor (mGluR1) signalling pathway, i.e. mGluR1alpha, G alpha q/G alpha 11 subunits of G q protein, inositol 1,4,5-trisphosphate receptor IP3R1, Homer1, protein kinase C PKCgamma, and diacylglycerol lipase DAGLalpha. Unlike PLCbeta4, PLCbeta3 was also distributed at low to moderate levels in PC axons, which were intense for IP3R1 and PKCgamma, low for G alpha q/G alpha 11, and negative for mGluR1alpha, Homer1, and DAGLalpha. By immunoelectron microscopy, PLCbeta3 was preferentially localized around the smooth endoplasmic reticulum in spines, dendrites, and axons of PCs, and also accumulated at the perisynapse of parallel fibre-PC synapses. Consistent with the ultrastructural localization, PLCbeta3 was biochemically enriched in the microsomal and postsynaptic density fractions. These results suggest that PLCbeta3 plays a major role in mediating mGluR1-dependent synaptic transmission, plasticity, and integration in PLCbeta3-dominant PCs, through eliciting Ca2+ release, protein phosphorylation, and endocannabinoid production at local somatodendritic compartments. Because PLCbeta3 can be activated by G betagamma subunits liberated from Gi/o and Gs proteins as well, axonal PLCbeta3 seems to modulate the conduction of action potentials through mediating local Ca2+ release and protein phosphorylation upon activation of a variety of G protein-coupled receptors other than mGluR1.

  2. Intermedin1-53 attenuates vascular smooth muscle cell calcification by inhibiting endoplasmic reticulum stress via cyclic adenosine monophosphate/protein kinase A pathway.

    PubMed

    Chang, Jin-Rui; Duan, Xiao-Hui; Zhang, Bao-Hong; Teng, Xu; Zhou, Ye-Bo; Liu, Yue; Yu, Yan-Rong; Zhu, Yi; Tang, Chao-Shu; Qi, Yong-Fen

    2013-10-01

    We previously reported that endoplasmic reticulum (ER) stress-mediated apoptosis participated in vascular calcification. Importantly, a novel paracrine/autocrine peptide intermedin1-53 (IMD1-53) in the vasculature inhibited vascular calcification in rats. But the mechanisms needed to be fully elucidated. Vascular smooth muscle cells (VSMCs) calcification was induced by CaCl2 and β-glycerophosphate. Tunicamycin (Tm) or dithiothreitol (DTT) was used to induce ER stress. We found that IMD1-53 (10(-7)mol/L) treatment significantly alleviated the protein expression of ER stress hallmarks activating transcription factor 4 (ATF4), ATF6, glucose-regulated protein 78 (GRP78) and GRP94 induced by Tm or DTT. ER stress occurred in early and late calcification of VSMCs but was inhibited by IMD1-53. These inhibitory effects of IMD1-53 were abolished by treatment with the protein kinase A (PKA) inhibitor H89. Pretreatment with IMD1-53 decreased the number of apoptotic VSMCs and downregulated protein expression of cleaved caspase 12 and C/EBP homologous protein (CHOP) in calcified VSMCs. Concurrently, IMD1-53 restored the loss of VSMC lineage markers and ameliorated calcium deposition and alkaline phosphatase activity in calcified VSMCs as well. The observation was further verified by Alizarin Red S staining, which showed that IMD1-53 reduced positive red nodules among calcified VSMCs. In conclusion, IMD1-53 attenuated VSMC calcification by inhibiting ER stress through cAMP/PKA signalling.

  3. iRAGE as a novel carboxymethylated peptide that prevents advanced glycation end product-induced apoptosis and endoplasmic reticulum stress in vascular smooth muscle cells.

    PubMed

    Maltais, Jean-Sébastien; Simard, Elie; Froehlich, Ulrike; Denault, Jean-Bernard; Gendron, Louis; Grandbois, Michel

    2016-02-01

    Advanced glycation end-products (AGE) and the receptor for AGE (RAGE) have been linked to numerous diabetic vascular complications. RAGE activation promotes a self-sustaining state of chronic inflammation and has been shown to induce apoptosis in various cell types. Although previous studies in vascular smooth muscle cells (VSMC) showed that RAGE activation increases vascular calcification and interferes with their contractile phenotype, little is known on the potential of RAGE to induce apoptosis in VSMC. Using a combination of apoptotic assays, we showed that RAGE stimulation with its ligand CML-HSA promotes apoptosis of VSMC. The formation of stress granules and the increase in the level of the associated protein HuR point toward RAGE-dependent endoplasmic reticulum (ER) stress, which is proposed as a key contributor of RAGE-induced apoptosis in VSMC as it has been shown to promote cell death via numerous mechanisms, including up-regulation of caspase-9. Chronic NF-κB activation and modulation of Bcl-2 homologs are also suspected to contribute to RAGE-dependent apoptosis in VSMC. With the goal of reducing RAGE signaling and its detrimental impact on VSMC, we designed a RAGE antagonist (iRAGE) derived from the primary amino acid sequence of HSA. The resulting CML peptide was selected for the high glycation frequency of the primary sequence in the native protein in vivo. Pretreatment with iRAGE blocked 69.6% of the increase in NF-κB signaling caused by RAGE activation with CML-HSA after 48h. Preincubation with iRAGE was successful in reducing RAGE-induced apoptosis, as seen through enhanced cell survival by SPR and reduced PARP cleavage. Activation of executioner caspases was 63.5% lower in cells treated with iRAGE before stimulation with CML-HSA. To our knowledge, iRAGE is the first antagonist shown to block AGE-RAGE interaction and we propose the molecule as an initial candidate for drug discovery.

  4. Cell density and growth-dependent down-regulation of both intracellular calcium responses to agonist stimuli and expression of smooth-surfaced endoplasmic reticulum in MC3T3-E1 osteoblast-like cells.

    PubMed

    Koizumi, Toshiyuki; Hikiji, Hisako; Shin, Wee Soo; Takato, Tsuyoshi; Fukuda, Satoru; Abe, Takahiro; Koshikiya, Noboru; Iwasawa, Kuniaki; Toyo-oka, Teruhiko

    2003-02-21

    A two-dimensional intracellular Ca(2+) ([Ca(2+)](i)) imaging system was used to examine the relationship between [Ca(2+)](i) handling and the proliferation of MC3T3-E1 osteoblast-like cells. The resting [Ca(2+)](i) level in densely cultured cells was 1.5 times higher than the [Ca(2+)](i) level in sparsely cultured cells or in other cell types (mouse fibroblasts, rat vascular smooth muscle cells, and bovine endothelial cells). A high resting [Ca(2+)](i) level may be specific for MC3T3-E1 cells. MC3T3-E1 cells were stimulated with ATP (10 microM), caffeine (10 mM), thapsigargin (1 microM), or ionomycin (10 microM), and the effect on the [Ca(2+)](i) level of MC3T3-E1 cells was studied. The percentage of responding cells and the degree of [Ca(2+)](i) elevation were high in the sparsely cultured cells and low in densely cultured cells. The rank order for the percentage of responding cells and magnitude of the Ca(2+) response to the stimuli was ionomycin > thapsigargin = ATP > caffeine and suggests the existence of differences among the various [Ca(2+)](i) channels. All Ca(2+) responses in the sparsely cultured MC3T3-E1 cells, unlike in other cell types, disappeared after the cells reached confluence. Heptanol treatment of densely cultured cells restored the Ca(2+) response, suggesting that cell-cell contact is involved with the confluence-dependent disappearance of the Ca(2+) response. Immunohistological analysis of type 1 inositol trisphosphate receptors and electron microscopy showed distinct expression of inositol trisphosphate receptor proteins and smooth-surfaced endoplasmic reticulum in sparsely cultured cells but reduced levels in densely cultured cells. These results indicate that the underlying basis of confluence-dependent [Ca(2+)](i) regulation is down-regulation of smooth-surfaced endoplasmic reticulum by cell-cell contacts.

  5. Male rats exposed in utero to di(n-butyl) phthalate: Age-related changes in Leydig cell smooth endoplasmic reticulum and testicular testosterone-biosynthesis enzymes/proteins.

    PubMed

    Motohashi, Masaya; Wempe, Michael F; Mutou, Tomoko; Takahashi, Hiroyuki; Kansaku, Norio; Ikegami, Masahiro; Inomata, Tomo; Asari, Masao; Wakui, Shin

    2016-01-01

    This study investigated the age-related (i.e., weeks 5, 7, 9, 14 and 17) morphological changes of Leydig cell smooth endoplasmic reticulum (LCs-ER) and testicular testosterone biosynthesis/protein expression in rats in utero exposed to di(n-butyl) phthalate (DBP) (intragastrically; 100mg/kg/day) on days 12-21 post-conception. Ultrastructural observations revealed the LCs-ER of the DBP group were non-dilated until peri-puberty, and thereafter decreased and disappeared. RT-PCR and Western blotting analyses revealed that StAR and P450scc levels in the DBP group were significantly lower at 5 and 7 weeks compared with the vehicle group but became similar during weeks 9-17. Although 3β-HSD, P450c17, and 17β-HSD levels of mRNA and protein in the DBP group were similar to the vehicle control group at 5 and 7 weeks of age, they were significantly lower during weeks 9-17. In utero DBP exposure results in age-related LCs-ER changes corresponding to reduction of testicular testosterone biosynthesis enzymes/associated proteins.

  6. The Gp78 ubiquitin ligase: probing endoplasmic reticulum complexity.

    PubMed

    St Pierre, Pascal; Nabi, Ivan R

    2012-02-01

    The endoplasmic reticulum (ER) has been classically divided, based on electron microscopy analysis, into parallel ribosome-studded rough ER sheets and a tubular smooth ER network. Recent studies have identified molecular constituents of the ER, the reticulons and DP1, that drive ER tubule formation and whose expression determines expression of ER sheets and tubules and thereby rough and smooth ER. However, segregation of the ER into only two domains remains simplistic and multiple functionally distinct ER domains necessarily exist. In this review, we will discuss the sub-organization of the ER in different domains focusing on the localization and role of the gp78 ubiquitin ligase in the mitochondria-associated smooth ER and on the evidence for a quality control ERAD domain.

  7. The Gp78 ubiquitin ligase: probing endoplasmic reticulum complexity.

    PubMed

    St Pierre, Pascal; Nabi, Ivan R

    2012-02-01

    The endoplasmic reticulum (ER) has been classically divided, based on electron microscopy analysis, into parallel ribosome-studded rough ER sheets and a tubular smooth ER network. Recent studies have identified molecular constituents of the ER, the reticulons and DP1, that drive ER tubule formation and whose expression determines expression of ER sheets and tubules and thereby rough and smooth ER. However, segregation of the ER into only two domains remains simplistic and multiple functionally distinct ER domains necessarily exist. In this review, we will discuss the sub-organization of the ER in different domains focusing on the localization and role of the gp78 ubiquitin ligase in the mitochondria-associated smooth ER and on the evidence for a quality control ERAD domain. PMID:22045301

  8. Selenium suppresses oxidative-stress-enhanced vascular smooth muscle cell calcification by inhibiting the activation of the PI3K/AKT and ERK signaling pathways and endoplasmic reticulum stress.

    PubMed

    Liu, Hongmei; Li, Xiaoming; Qin, Fei; Huang, Kaixun

    2014-03-01

    Vascular calcification is a prominent feature of many diseases, including atherosclerosis, and it has emerged as a powerful predictor of cardiovascular morbidity and mortality. A number of studies have examined the association between selenium and risk of cardiovascular diseases, but little is known about the role of selenium in vascular calcification. To determine the role of selenium in regulating vascular calcification, we assessed the effect of sodium selenite on oxidative-stress-enhanced vascular smooth muscle cell (VSMC) calcification and the underlying mechanism. Oxidative stress induced by xanthine/xanthine oxidase increased apoptosis, as determined by Hoechst 33342 staining and annexin V/propidium iodide staining, and it enhanced osteoblastic differentiation and calcification of VSMCs, on the basis of alkaline phosphatase activity, the expression of Runx2 and type I collagen, and calcium deposition. These effects of oxidative stress were significantly inhibited by selenite. The following processes may explain the inhibitory effects of selenite: (1) selenite significantly suppressed oxidative stress, as evidenced by the decrease of the oxidative status of the cell and lipid peroxidation levels, as well as by the increase of the total protein thiol content and the activity of the antioxidant selenoenzyme glutathione peroxidase; (2) selenite significantly attenuated oxidative-stress-induced activation of the phosphatidylinositol 3-kinase/AKT and extracellular-signal-regulated kinase signaling pathways, resulting in decreased osteoblastic differentiation of VSMCs; (3) selenite significantly inhibited oxidative-stress-activated endoplasmic reticulum stress, thereby leading to decreased apoptosis. Our results suggest a potential role of selenium in the prevention of vascular calcification, which may provide more mechanistic insights into the relationship between selenium and cardiovascular diseases.

  9. Deficiency in parvalbumin, but not in calbindin D-28k upregulates mitochondrial volume and decreases smooth endoplasmic reticulum surface selectively in a peripheral, subplasmalemmal region in the soma of Purkinje cells.

    PubMed

    Chen, G; Racay, P; Bichet, S; Celio, M R; Eggli, P; Schwaller, B

    2006-09-29

    The Ca(2+)-binding proteins parvalbumin (PV) and calbindin D-28k (CB) are key players in the intracellular Ca(2+)-buffering in specific cells including neurons and have profound effects on spatiotemporal aspects of Ca(2+) transients. The previously observed increase in mitochondrial volume density in fast-twitch muscle of PV-/- mice is viewed as a specific compensation mechanism to maintain Ca(2+) homeostasis. Since cerebellar Purkinje cells (PC) are characterized by high expression levels of the Ca(2+) buffers PV and CB, the question was raised, whether homeostatic mechanisms are induced in PC lacking these buffers. Mitochondrial volume density, i.e. relative mitochondrial mass was increased by 40% in the soma of PV-/- PC. Upregulation of mitochondrial volume density was not homogenous throughout the soma, but was selectively restricted to a peripheral region of 1.5 microm width underneath the plasma membrane. Accompanied was a decreased surface of subplasmalemmal smooth endoplasmic reticulum (sPL-sER) in a shell of 0.5 microm thickness underneath the plasma membrane. These alterations were specific for the absence of the "slow-onset" buffer PV, since in CB-/- mice neither changes in peripheral mitochondria nor in sPL-sER were observed. This implicates that the morphological alterations are aimed to specifically substitute the function of the slow buffer PV. We propose a novel concept that homeostatic mechanisms of components involved in Ca(2+) homeostasis do not always occur at the level of similar or closely related molecules. Rather the cell attempts to restore spatiotemporal aspects of Ca(2+) signals prevailing in the undisturbed (wildtype) situation by subtly fine tuning existing components involved in the regulation of Ca(2+) fluxes.

  10. Dense-cored vesicles, smooth endoplasmic reticulum, and mitochondria are closely associated with non-specialized parts of plasma membrane of nerve terminals: implications for exocytosis and calcium buffering by intraterminal organelles.

    PubMed

    Lysakowski, A; Figueras, H; Price, S D; Peng, Y Y

    1999-01-18

    To determine whether there are anatomical correlates for intraterminal Ca2+ stores to regulate exocytosis of dense-cored vesicles (DCVs) and whether these stores can modulate exocytosis of synaptic vesicles, we studied the spatial distributions of DCVs, smooth endoplasmic reticulum (SER), and mitochondria in 19 serially reconstructed nerve terminals in bullfrog sympathetic ganglia. On average, each bouton had three active zones, 214 DCVs, 26 SER fragments (SERFs), and eight mitochondria. DCVs, SERFs and mitochondria were located, on average, 690, 624, and 526 nm, respectively, away from active zones. Virtually no DCVs were within "docking" (i.e., < or = 50 nm) distances of the active zones. Thus, it is unlikely that DCV exocytosis occurs at active zones via mechanisms similar to those for exocytosis of synaptic vesicles. Because there were virtually no SERFs or mitochondria within 50 nm of any active zone, Ca2+ modulation by these organelles is unlikely to affect ACh release evoked by a single action potential. In contrast, 30% of DCVs and 40% of SERFs were located within 50 nm of the nonspecialized regions of the plasma membrane. Because each bouton had at least one SERF within 50 nm of the plasma membrane and most of these SERFs had DCVs, but not mitochondria, near them, it is possible for Ca2+ release from the SER to provide the Ca2+ necessary for DCV exocytosis. The fact that 60% of the mitochondria had some part within 50 nm of the plasma membrane means that it is possible for mitochondrial Ca2+ buffering to affect DCV exocytosis.

  11. Why can organic liquids move easily on smooth alkyl-terminated surfaces?

    PubMed

    Urata, Chihiro; Masheder, Benjamin; Cheng, Dalton F; Miranda, Daniel F; Dunderdale, Gary J; Miyamae, Takayuki; Hozumi, Atsushi

    2014-04-15

    The dynamic dewettability of a smooth alkyl-terminated sol-gel hybrid film surface against 17 probe liquids (polar and nonpolar, with high and low surface tensions) was systematically investigated using contact angle (CA) hysteresis and substrate tilt angle (TA) measurements, in terms of their physicochemical properties such as surface tension, molecular weight/volume, dielectric constant, density, and viscosity. We found that the dynamic dewettability of the hybrid film markedly depended not on the surface tensions but on the dielectric constants of the probe liquids, displaying lower resistance to liquid drop movement with decreasing dielectric constant (ε < 30). Interfacial analysis using the sum-frequency generation (SFG) technique confirmed that the conformation of surface-tethered alkyl chains was markedly altered before and after contact with the different types of probe liquids. When probe liquids with low dielectric constants were in contact with our surface, CH3 groups were preferentially exposed at the solid/liquid interface, leading to a reduction in surface energy. Because of such local changes in surface energy at the three-phase contact line of the probe liquid, the contact line can move continuously from low-surface-energy (solid/liquid) areas to surrounding high-surface-energy (solid/air) areas without pinning. Consequently, the organic probe liquids with low dielectric constants can move easily and roll off when tilted only slightly, independent of the magnitude of CAs, without relying on conventional surface roughening and perfluorination.

  12. [Influence of prostatilen on smooth muscle organs functional activity in surgical patients (clinical and experimental study)].

    PubMed

    Al'-Shukri, S Kh; Aĭvazian, A I; Barabanov, S V; Barabanova, V V; Bobkov, Iu A; Gorbachev, A G; Parastaeva, M M

    1999-01-01

    The action of prostatilen on contractile activity of smooth muscles of isolated line slices of urine bladder of Wistar rats (myography) and arterial vessels of cat kidneys (resistography) was studied. On the basis of clinical cases effectiveness of prostatilen was analysed as a treatment restorting urine bladder function in acute reflex urinary retention after operations in the area of rectal sphincter, as well as in treatment of patients with chronic prostatitis. It is shown, that prostatilen produces contractile action on smooth muscles of renal blood vessels in cats and urine bladder walls in rats and it raises contractile activity of smooth muscles of human urine bladder. The results of experimental and clinical investigations make it possible to recommend the application of this bioregulating preparation for treatment and prophylaxis of disturbances in urination.

  13. BIOGENESIS OF ENDOPLASMIC RETICULUM MEMBRANES

    PubMed Central

    Dallner, Gustav; Siekevitz, Philip; Palade, George E.

    1966-01-01

    The development of the endoplasmic reticulum of rat hepatocytes was studied during a period of rapid cell differentiation, i.e., from 3 days before to 8 days after birth. Before birth, the ER increases in volume, remaining predominantly rough surfaced; after birth, the increase continues but affects mainly the smooth-surfaced part of the system. These changes are reflected in variations of the RNA/protein and PLP/protein ratios of microsomal fractions: the first decreases, while the second increases, with age. The analysis of microsomal membranes and of microsomal lipids indicates that the PLP/protein ratio, the distribution of phospholipids, and the rate of P32 incorporation into these phospholipids show little variation over the period examined and are comparable to values found in adult liver. Fatty acid composition of total phosphatides undergoes, however, drastic changes after birth. During the period of rapid ER development in vivo incorporation of leucine-C14 and glycerol-C14 into the proteins and lipids of microsomal membranes is higher in the rough-than in the smooth-surfaced microsomes, for the first hours after the injection of the label; later on (∼10 hr) the situation is reversed. These results strongly suggest that new membrane is synthesized in the rough ER and subsequently transferred to the smooth ER. PMID:5966178

  14. Optimization of the current self-assembled urinary bladder model: Organ-specific stroma and smooth muscle inclusion

    PubMed Central

    Orabi, Hazem; Rousseau, Alexandre; Laterreur, Veronique; Bolduc, Stephane

    2015-01-01

    Introduction: Due to the complications associated with the use of non-native biomaterials and the lack of local tissues, bioengineered tissues are required for surgical reconstruction of complex urinary tract diseases, including those of the urinary bladder. The self-assembly method of matrix formation using autologous stromal cells obviates the need for exogenous biomaterials. We aimed at creating novel ex-vivo multilayer urinary tissue from a single bladder biopsy. Methods: After isolating urothelial, bladder stromal and smooth muscle cells from bladder biopsies, we produced 2 models of urinary equivalents: (1) the original one with dermal fibroblasts and (2) the new one with bladder stromal cells. Dermal fibroblasts and bladder stromal cells were stimulated to form an extracellular matrix, followed by sequential seeding of smooth muscle cells and urothelial cells. Stratification and cellular differentiation were assessed by histology, immunostaining and electron microscopy. Barrier function was checked with the permeability test. Biomechanical properties were assessed with uniaxinal tensile strength, elastic modulus, and failure strain. Results: Both urinary equivalents could be handled easily and did not contract. Stratified epithelium, intact basement membrane, fused matrix, and prominent muscle layer were detected in both urinary equivalents. Bladder stromal cell-based constructs had terminally differentiated urothelium and more elasticity than dermal fibroblasts-based equivalents. Permeation studies showed that both equivalents were comparable to native tissues. Conclusions: Organ-specific stromal cells produced urinary tissues with more terminally differentiated urothelium and better biomechanical characteristics than non-specific stromal cells. Smooth muscle cells could be incorporated into the self-assembled tissues effectively. This multilayer tissue can be used as a urethral graft or as a bladder model for disease modelling and pharmacotherapeutic

  15. Ultra-thin and smooth transparent electrode for flexible and leakage-free organic light-emitting diodes

    PubMed Central

    Ok, Ki-Hun; Kim, Jiwan; Park, So-Ra; Kim, Youngmin; Lee, Chan-Jae; Hong, Sung-Jei; Kwak, Min-Gi; Kim, Namsu; Han, Chul Jong; Kim, Jong-Woong

    2015-01-01

    A smooth, ultra-flexible, and transparent electrode was developed from silver nanowires (AgNWs) embedded in a colorless polyimide (cPI) by utilizing an inverted film-processing method. The resulting AgNW-cPI composite electrode had a transparency of >80%, a low sheet resistance of 8 Ω/□, and ultra-smooth surfaces comparable to glass. Leveraging the robust mechanical properties and flexibility of cPI, the thickness of the composite film was reduced to less than 10 μm, which is conducive to extreme flexibility. This film exhibited mechanical durability, for both outward and inward bending tests, up to a bending radius of 30 μm, while maintaining its electrical performance under cyclic bending (bending radius: 500 μm) for 100,000 iterations. Phosphorescent, blue organic light-emitting diodes (OLEDs) were fabricated using these composites as bottom electrodes (anodes). Hole-injection was poor, because AgNWs were largely buried beneath the composite's surface. Thus, we used a simple plasma treatment to remove the thin cPI layer overlaying the nanowires without introducing other conductive materials. As a result, we were able to finely control the flexible OLEDs' electroluminescent properties using the enlarged conductive pathways. The fabricated flexible devices showed only slight performance reductions of <3% even after repeated foldings with a 30 μm bending radius. PMID:25824143

  16. Nox NADPH Oxidases and the Endoplasmic Reticulum

    PubMed Central

    Araujo, Thaís L.S.; Abrahão, Thalita B.

    2014-01-01

    Abstract Significance: Understanding isoform- and context-specific subcellular Nox reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase compartmentalization allows relevant functional inferences. This review addresses the interplay between Nox NADPH oxidases and the endoplasmic reticulum (ER), an increasingly evident player in redox pathophysiology given its role in redox protein folding and stress responses. Recent Advances: Catalytic/regulatory transmembrane subunits are synthesized in the ER and their processing includes folding, N-glycosylation, heme insertion, p22phox heterodimerization, as shown for phagocyte Nox2. Dual oxidase (Duox) maturation also involves the regulation by ER-resident Duoxa2. The ER is the activation site for some isoforms, typically Nox4, but potentially other isoforms. Such location influences redox/Nox-mediated calcium signaling regulation via ER targets, such as sarcoendoplasmic reticulum calcium ATPase (SERCA). Growing evidence suggests that Noxes are integral signaling elements of the unfolded protein response during ER stress, with Nox4 playing a dual prosurvival/proapoptotic role in this setting, whereas Nox2 enhances proapoptotic signaling. ER chaperones such as protein disulfide isomerase (PDI) closely interact with Noxes. PDI supports growth factor-dependent Nox1 activation and mRNA expression, as well as migration in smooth muscle cells, and PDI overexpression induces acute spontaneous Nox activation. Critical Issues: Mechanisms of PDI effects include possible support of complex formation and RhoGTPase activation. In phagocytes, PDI supports phagocytosis, Nox activation, and redox-dependent interactions with p47phox. Together, the results implicate PDI as possible Nox organizer. Future Directions: We propose that convergence between Noxes and ER may have evolutive roots given ER-related functional contexts, which paved Nox evolution, namely calcium signaling and pathogen killing. Overall, the interplay between

  17. Artery Tertiary Lymphoid Organs Control Aorta Immunity and Protect against Atherosclerosis via Vascular Smooth Muscle Cell Lymphotoxin β Receptors

    PubMed Central

    Hu, Desheng; Mohanta, Sarajo K.; Yin, Changjun; Peng, Li; Ma, Zhe; Srikakulapu, Prasad; Grassia, Gianluca; MacRitchie, Neil; Dever, Gary; Gordon, Peter; Burton, Francis L.; Ialenti, Armando; Sabir, Suleman R.; McInnes, Iain B.; Brewer, James M.; Garside, Paul; Weber, Christian; Lehmann, Thomas; Teupser, Daniel; Habenicht, Livia; Beer, Michael; Grabner, Rolf; Maffia, Pasquale; Weih, Falk; Habenicht, Andreas J.R.

    2015-01-01

    Summary Tertiary lymphoid organs (TLOs) emerge during nonresolving peripheral inflammation, but their impact on disease progression remains unknown. We have found in aged Apoe−/− mice that artery TLOs (ATLOs) controlled highly territorialized aorta T cell responses. ATLOs promoted T cell recruitment, primed CD4+ T cells, generated CD4+, CD8+, T regulatory (Treg) effector and central memory cells, converted naive CD4+ T cells into induced Treg cells, and presented antigen by an unusual set of dendritic cells and B cells. Meanwhile, vascular smooth muscle cell lymphotoxin β receptors (VSMC-LTβRs) protected against atherosclerosis by maintaining structure, cellularity, and size of ATLOs though VSMC-LTβRs did not affect secondary lymphoid organs: Atherosclerosis was markedly exacerbated in Apoe−/−Ltbr−/− and to a similar extent in aged Apoe−/−Ltbrfl/flTagln-cre mice. These data support the conclusion that the immune system employs ATLOs to organize aorta T cell homeostasis during aging and that VSMC-LTβRs participate in atherosclerosis protection via ATLOs. PMID:26084025

  18. Rear Polarization of the Microtubule-Organizing Center in Neointimal Smooth Muscle Cells Depends on PKCα, ARPC5, and RHAMM

    PubMed Central

    Silverman-Gavrila, Rosalind; Silverman-Gavrila, Lorelei; Hou, Guangpei; Zhang, Ming; Charlton, Milton; Bendeck, Michelle P.

    2011-01-01

    Directed migration of smooth muscle cells (SMCs) from the media to the intima in arteries occurs during atherosclerotic plaque formation and during restenosis after angioplasty or stent application. The polarized orientation of the microtubule-organizing center (MTOC) is a key determinant of this process, and we therefore investigated factors that regulate MTOC polarity in vascular SMCs. SMCs migrating in vivo from the medial to the intimal layer of the rat carotid artery following balloon catheter injury were rear polarized, with the MTOC located posterior of the nucleus. In tissue culture, migrating neointimal cells maintained rear polarization, whereas medial cells were front polarized. Using phosphoproteomic screening and mass spectrometry, we identified ARPC5 and RHAMM as protein kinase C (PKC)-phosphorylated proteins associated with rear polarization of the MTOC in neointimal SMCs. RNA silencing of ARPC5 and RHAMM, PKC inhibition, and transfection with a mutated nonphosphorylatable ARPC5 showed that these proteins regulate rear polarization by organizing the actin and microtubule cytoskeletons in neointimal SMCs. Both ARPC5 and RHAMM, in addition to PKC, were required for migration of neointimal SMCs. PMID:21281821

  19. Smooth Muscle Strips for Intestinal Tissue Engineering

    PubMed Central

    Walthers, Christopher M.; Lee, Min; Wu, Benjamin M.; Dunn, James C. Y.

    2014-01-01

    Functionally contracting smooth muscle is an essential part of the engineered intestine that has not been replicated in vitro. The purpose of this study is to produce contracting smooth muscle in culture by maintaining the native smooth muscle organization. We employed intact smooth muscle strips and compared them to dissociated smooth muscle cells in culture for 14 days. Cells isolated by enzymatic digestion quickly lost maturity markers for smooth muscle cells and contained few enteric neural and glial cells. Cultured smooth muscle strips exhibited periodic contraction and maintained neural and glial markers. Smooth muscle strips cultured for 14 days also exhibited regular fluctuation of intracellular calcium, whereas cultured smooth muscle cells did not. After implantation in omentum for 14 days on polycaprolactone scaffolds, smooth muscle strip constructs expressed high levels of smooth muscle maturity markers as well as enteric neural and glial cells. Intact smooth muscle strips may be a useful component for engineered intestinal smooth muscle. PMID:25486279

  20. [Endoplasmic reticulum stress response in osteogenesis].

    PubMed

    Saito, Atsushi; Imaizumi, Kazunori

    2013-11-01

    Various cellular conditions such as synthesis of abundant proteins, expressions of mutant proteins and oxidative stress lead to accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) lumen. This type of stress is called ER stress. The excessive ER stress causes cellular damages followed by apoptosis. When ER stress occurs, cells are activated ER stress response (unfolded protein response) to avoid cellular damages. Recently, it has been clear that ER stress response plays crucial roles not only in cell survival after ER stress but also in regulating various cellular functions and tissue formations. In particular, ER stress and ER stress response regulate protein quality control, secretory protein production, and smooth secretion of proteins in the cells such as osteoblasts which synthesize and secrete enormous matrix proteins.

  1. An ultrathin, smooth, and low-loss Al-doped Ag film and its application as a transparent electrode in organic photovoltaics.

    PubMed

    Zhang, Cheng; Zhao, Dewei; Gu, Deen; Kim, Hyunsoo; Ling, Tao; Wu, Yi-Kuei Ryan; Guo, L Jay

    2014-08-27

    An ultrathin, smooth, and low-loss Ag film without a wetting layer is achieved by co-depositing a small amount of Al into Ag. The film can be as thin as 6 nm, with a roughness below 1 nm and excellent mechanical flexibility. Organic photovoltaics that use these thin films as transparent electrode show superior efficiency to their indium tin oxide (ITO) counterparts because of improved photon management. PMID:24943876

  2. Isolation of Endoplasmic Reticulum Fractions from Mammary Epithelial Tissue.

    PubMed

    Chanat, Eric; Le Parc, Annabelle; Lahouassa, Hichem; Badaoui, Bouabid

    2016-06-01

    In the mammary glands of lactating animals, the mammary epithelial cells that surround the lumen of the acini produce and secrete copious amounts of milk. Functional differentiation of these mammary epithelial cells depends on the development of high-efficiency secretory pathways, notably for protein and lipid secretion. Protein secretion is a fundamental process common to all animal cells that involves a subset of cellular organelles, including the endoplasmic reticulum and the Golgi apparatus. In contrast, en masse secretion of triglycerides and cholesterol esters in the form of milk fat globules is a unique feature of the mammary epithelial cell. Cytoplasmic lipid droplets, the intracellular precursors of milk fat globules, originate from the endoplasmic reticulum, as do most milk-specific proteins. This organelle is therefore pivotal in the biogenesis of milk components. Fractionation of the cell into its subcellular parts is an approach that has proven very powerful for understanding organelle function and for studying the specific role of an organelle in a given cell activity. Here we describe a method for the purification of both smooth and rough microsomes, the membrane-bound endoplasmic reticulum fragments that form from endoplasmic reticulum domains when cells are broken up, from mammary gland tissue at lactation.

  3. Smooth Sailing.

    ERIC Educational Resources Information Center

    Price, Beverley; Pincott, Maxine; Rebman, Ashley; Northcutt, Jen; Barsanti, Amy; Silkunas, Betty; Brighton, Susan K.; Reitz, David; Winkler, Maureen

    1999-01-01

    Presents discipline tips from several teachers to keep classrooms running smoothly all year. Some of the suggestions include the following: a bear-cave warning system, peer mediation, a motivational mystery, problem students acting as the teacher's assistant, a positive-behavior-reward chain, a hallway scavenger hunt (to ensure quiet passage…

  4. Mechanical strain induces specific changes in the synthesis and organization of proteoglycans by vascular smooth muscle cells.

    PubMed

    Lee, R T; Yamamoto, C; Feng, Y; Potter-Perigo, S; Briggs, W H; Landschulz, K T; Turi, T G; Thompson, J F; Libby, P; Wight, T N

    2001-04-27

    In the mechanically active environment of the artery, cells sense mechanical stimuli and regulate extracellular matrix structure. In this study, we explored the changes in synthesis of proteoglycans by vascular smooth muscle cells in response to precisely controlled mechanical strains. Strain increased mRNA for versican (3.2-fold), biglycan (2.0-fold), and perlecan (2.0-fold), whereas decorin mRNA levels decreased to a third of control levels. Strain also increased versican, biglycan, and perlecan core proteins, with a concomitant decrease in decorin core protein. Deformation did not alter the hydrodynamic size of proteoglycans as evidenced by molecular sieve chromatography but increased sulfate incorporation in both chondroitin/dermatan sulfate proteoglycans and heparan sulfate proteoglycans (p < 0.05 for both). Using DNA microarrays, we also identified the gene for the hyaluronan-linking protein TSG6 as mechanically induced in smooth muscle cells. Northern analysis confirmed a 4.0-fold increase in steady state mRNA for TSG6 following deformation. Size exclusion chromatography under associative conditions showed that versican-hyaluronan aggregation was enhanced following deformation. These data demonstrate that mechanical deformation increases specific vascular smooth muscle cell proteoglycan synthesis and aggregation, indicating a highly coordinated extracellular matrix response to biomechanical stimulation. PMID:11278699

  5. Obesity and endoplasmic reticulum (ER) stresses

    PubMed Central

    Tripathi, Yamini B.; Pandey, Vivek

    2012-01-01

    In obesity, the adipose cells behave as inflammatory source and result to low grade inflammation. This systemic inflammation along with oxidative stress is a silent killer and damages other vital organs also. High metabolic process, induced due to high nutritional intake, results to endoplasmic reticulum (ER) stress and mitochondrial stress. This review describes the triggering factor and basic mechanism behind the obesity mediated these stresses in relation to inflammation. Efforts have been made to describe the effect-response cycle between adipocytes and non-adipocyte cells with reference to metabolic syndrome (MS). PMID:22891067

  6. Association of Spectrin-Like Proteins with the Actin-Organized Aggregate of Endoplasmic Reticulum in the Spitzenkörper of Gravitropically Tip-Growing Plant Cells1

    PubMed Central

    Braun, Markus

    2001-01-01

    Spectrin-like epitopes were immunochemically detected and immunofluorescently localized in gravitropically tip-growing rhizoids and protonemata of characean algae. Antiserum against spectrin from chicken erythrocytes showed cross-reactivity with rhizoid proteins at molecular masses of about 170 and 195 kD. Confocal microscopy revealed a distinct spherical labeling of spectrin-like proteins in the apices of both cell types tightly associated with an apical actin array and a specific subdomain of endoplasmic reticulum (ER), the ER aggregate. The presence of spectrin-like epitopes, the ER aggregate, and the actin cytoskeleton are strictly correlated with active tip growth. Application of cytochalasin D and A23187 has shown that interfering with actin or with the calcium gradient, which cause the disintegration of the ER aggregate and abolish tip growth, inhibits labeling of spectrin-like proteins. At the beginning of the graviresponse in rhizoids the labeling of spectrin-like proteins remained in its symmetrical position at the cell tip, but was clearly displaced to the upper flank in gravistimulated protonemata. These findings support the hypothesis that a displacement of the Spitzenkörper is required for the negative gravitropic response in protonemata, but not for the positive gravitropic response in rhizoids. It is evident that the actin/spectrin system plays a role in maintaining the organization of the ER aggregate and represents an essential part in the mechanism of gravitropic tip growth. PMID:11299343

  7. Determination of the Young's modulus of the epicuticle of the smooth adhesive organs of Carausius morosus using tensile testing.

    PubMed

    Bennemann, Michael; Backhaus, Stefan; Scholz, Ingo; Park, Daesung; Mayer, Joachim; Baumgartner, Werner

    2014-10-15

    Adhesive organs like arolia of insects allow these animals to climb on different substrates by creating high adhesion forces. According to the Dahlquist criterion, adhesive organs must be very soft, exhibiting an effective Young's modulus of below 100 kPa to adhere well to substrates. Such a low effective Young's modulus allows the adhesive organs to make almost direct contact with the substrate and results in van der Waals forces along with capillary forces. In previous studies, the effective Young's moduli of adhesive organs were determined using indentation tests, revealing their structure to be very soft. However, adhesive organs show a layered structure, thus the measured values comprise the effective Young's moduli of several layers of the adhesive organs. In this study, a new approach is illustrated to measure the Young's modulus of the outermost layer of the arolium, i.e. of the epicuticle, of the stick insect Carausius morosus. As a result of the epicuticle being supported by upright fibres, tensile tests allow the determination of the Young's modulus of the epicuticle with hardly influence from subjacent layers. In our tensile tests, arolia of stick insects adhering on a latex membrane were stretched by stretching the membrane while the elongation of the contact area between an arolium and the membrane was recorded. For analysis, mathematical models of the mechanical system were developed. When fed with the observed elongations, these models yield estimates for the Young's modulus of the epicuticle of approximately 100 MPa. Thus, in arolia, a very thin layer (~225 nm) of a rather stiff material, which is less susceptible to abrasion, makes contact with the substrates, whereas the inner fibrous structure of arolia is responsible for their softness.

  8. Determination of the Young's modulus of the epicuticle of the smooth adhesive organs of Carausius morosus using tensile testing

    PubMed Central

    Bennemann, Michael; Backhaus, Stefan; Scholz, Ingo; Park, Daesung; Mayer, Joachim; Baumgartner, Werner

    2014-01-01

    Adhesive organs like arolia of insects allow these animals to climb on different substrates by creating high adhesion forces. According to the Dahlquist criterion, adhesive organs must be very soft, exhibiting an effective Young's modulus of below 100 kPa to adhere well to substrates. Such a low effective Young's modulus allows the adhesive organs to make almost direct contact with the substrate and results in van der Waals forces along with capillary forces. In previous studies, the effective Young's moduli of adhesive organs were determined using indentation tests, revealing their structure to be very soft. However, adhesive organs show a layered structure, thus the measured values comprise the effective Young's moduli of several layers of the adhesive organs. In this study, a new approach is illustrated to measure the Young's modulus of the outermost layer of the arolium, i.e. of the epicuticle, of the stick insect Carausius morosus. As a result of the epicuticle being supported by upright fibres, tensile tests allow the determination of the Young's modulus of the epicuticle with hardly influence from subjacent layers. In our tensile tests, arolia of stick insects adhering on a latex membrane were stretched by stretching the membrane while the elongation of the contact area between an arolium and the membrane was recorded. For analysis, mathematical models of the mechanical system were developed. When fed with the observed elongations, these models yield estimates for the Young's modulus of the epicuticle of approximately 100 MPa. Thus, in arolia, a very thin layer (~225 nm) of a rather stiff material, which is less susceptible to abrasion, makes contact with the substrates, whereas the inner fibrous structure of arolia is responsible for their softness. PMID:25214493

  9. Molluscan visceral muscle fine structure. General structure and sarcolemmal organization in the smooth muscle of the intestinal wall of Buccinum undatum L.

    PubMed

    Hunt, S

    1981-01-01

    Fine structure of intestinal muscle in the gastropod Buccinum undatum is described. Myofibrillar organization is typical of non-pseudostriated molluscan muscles. The dense body system is poorly developed but there are extensive attachments plaques. The sarcolemma is elaborately modified. Deep infoldings of the membrane give the cells an irregular outline. Such infoldings enclose extracellular matrix and are associated with attachment plaques. Arising from these and from the general sarcolemma are numerous tubular membranous invaginations ending blindly at varying depth in the sarcoplasm. These structures have a helical coat of particles on the cytoplasmic face. Associated with both types of invagination are subsarcolemmal vesicles. The possibility that the tubular invaginations are analogues of vertebrate smooth muscle caveolae or striated muscle T-tubules and that the vesicles are the corresponding sarcoplasmic reticulum is discussed. The occurrence of such structures in molluscan muscle and elsewhere is reviewed.

  10. In vitro differentiation of endometrial regenerative cells into smooth muscle cells: A potential approach for the management of pelvic organ prolapse

    PubMed Central

    CHEN, XIUHUI; KONG, XIANCHAO; LIU, DONGZHE; GAO, PENG; ZHANG, YANHUA; LI, PEILING; LIU, MEIMEI

    2016-01-01

    Pelvic organ prolapse (POP), is a common condition in parous women. Synthetic mesh was once considered to be the standard of care; however, the use of synthetic mesh is limited by severe complications, thus creating a need for novel approaches. The application of cell-based therapy with stem cells may be an ideal alternative, and specifically for vaginal prolapse. Abnormalities in vaginal smooth muscle (SM) play a role in the pathogenesis of POP, indicating that smooth muscle cells (SMCs) may be a potential therapeutic target. Endometrial regenerative cells (ERCs) are an easily accessible, readily available source of adult stem cells. In the present study, ERCs were obtained from human menstrual blood, and phase contrast microscopy and flow cytometry were performed to characterize the morphology and phenotype of the ERCs. SMC differentiation was induced by a transforming growth factor β1-based medium, and the induction conditions were optimized. We defined the SMC characteristics of the induced cells with regard to morphology and marker expression using transmission electron microscopy, western blot analysis, immunocytofluorescence and RT-PCR. Examining the expression of the components of the Smad pathway and phosphorylated Smad2 and Smad3 by western blot analysis, RT-PCR and quantitative PCR demonstrated that the 'TGFBR2/ALK5/Smad2 and Smad3' pathway is involved, and both Smad2 and Smad3 participated in SMC differentiation. Taken together, these findings indicate that ERCs may be a promising cell source for cellular therapy aimed at modulating SM function in the vagina wall and pelvic floor in order to treat POP. PMID:27221348

  11. Involvement of Organic Cation Transporter-3 and Plasma Membrane Monoamine Transporter in Serotonin Uptake in Human Brain Vascular Smooth Muscle Cells

    PubMed Central

    Li, Rachel W. S.; Yang, Cui; Kwan, Y. W.; Chan, S. W.; Lee, Simon M. Y.; Leung, George P. H.

    2013-01-01

    The serotonin (5-HT) uptake system is supposed to play a crucial part in vascular functions by “fine-tuning” the local concentration of 5-HT in the vicinity of 5-HT2 receptors in vascular smooth muscle cells. In this study, the mechanism of 5-HT uptake in human brain vascular smooth muscle cells (HBVSMCs) was investigated. [3H]5-HT uptake in HBVSMCs was Na+-independent. Kinetic analyses of [3H]5-HT uptake in HBVSMCs revealed a Km of 50.36 ± 10.2 mM and a Vmax of 1033.61 ± 98.86 pmol/mg protein/min. The specific serotonin re-uptake transporter (SERT) inhibitor citalopram, the specific norepinephrine transporter (NET) inhibitor desipramine, and the dopamine transporter (DAT) inhibitor GBR12935 inhibited 5-HT uptake in HBVSMCs with IC50 values of 97.03 ± 40.10, 10.49 ± 5.98, and 2.80 ± 1.04 μM, respectively. These IC50 values were 100-fold higher than data reported by other authors, suggesting that those inhibitors were not blocking their corresponding transporters. Reverse transcription-polymerase chain reaction results demonstrated the presence of mRNA for organic cation transporter (OCT)-3 and plasma membrane monoamine transporter (PMAT), but the absence of OCT-1, OCT-2, SERT, NET, and DAT. siRNA knockdown of OCT-3 and PMAT specifically attenuated 5-HT uptake in HBVSMCs. It is concluded that 5-HT uptake in HBVSMCs was mediated predominantly by a low-affinity and Na+-independent mechanism. The most probable candidates are OCT-3 and PMAT, but not the SERT. PMID:23407616

  12. Relationship of the Topological Distances and Activities between mPGES-1 and COX-2 versus COX-1: Implications of the Different Post-Translational Endoplasmic Reticulum Organizations of COX-1 and COX-2.

    PubMed

    Akasaka, Hironari; So, Shui-Ping; Ruan, Ke-He

    2015-06-16

    In vascular inflammation, prostaglandin E2 (PGE₂) is largely biosynthesized by microsomal PGE₂ synthase-1 (mPGES-1), competing with other downstream eicosanoid-synthesizing enzymes, such as PGIS, a synthase of a vascular protector prostacyclin (PGI₂), to isomerize the cyclooxygenase (COX)-2-derived prostaglandin H2 (PGH₂). In this study, we found that a majority of the product from the cells co-expressing human COX-2, mPGES-1, and PGIS was PGE₂. We hypothesize that the molecular and cellular mechanisms are related to the post-translational endoplasmic reticulum (ER) arrangement of those enzymes. A set of fusion enzymes, COX-2-linker [10 amino acids (aa)]-PGIS and COX-2-linker (22 amino acids)-PGIS, were created as "The Bioruler", in which the 10 and 22 amino acids are defined linkers with known helical structures and distances (14.4 and 30.8 Å, respectively). Our experiments have shown that the efficiency of PGI₂ biosynthesis was reduced when the separation distance increased from 10 to 22 amino acids. When COX-2-10aa-PGIS (with a 14.4 Å separation) was co-expressed with mPGES-1 on the ER membrane, a major product was PGE₂, but not PGI₂. However, expression of COX-2-10aa-PGIS and mPGES-1 on a separated ER with a distance of ≫30.8 Å reduced the level of PGE₂ production. These data indicated that the mPGES-1 is "complex-likely" colocalized with COX-2 within a distance of 14.4 Å. In addition, the cells co-expressing COX-1-10aa-PGIS and mPGES-1 produced PGI₂ mainly, but not PGE₂. This indicates that mPGES-1 is expressed much farther from COX-1. These findings have led to proposed models showing the different post-translational ER organization between COX-2 and COX-1 with respect to the topological arrangement of the mPGES-1 during vascular inflammation.

  13. Endoplasmic Reticulum Stress and Ethanol Neurotoxicity.

    PubMed

    Yang, Fanmuyi; Luo, Jia

    2015-10-14

    Ethanol abuse affects virtually all organ systems and the central nervous system (CNS) is particularly vulnerable to excessive ethanol exposure. Ethanol exposure causes profound damages to both the adult and developing brain. Prenatal ethanol exposure induces fetal alcohol spectrum disorders (FASD) which is associated with mental retardation and other behavioral deficits. A number of potential mechanisms have been proposed for ethanol-induced brain damage; these include the promotion of neuroinflammation, interference with signaling by neurotrophic factors, induction of oxidative stress, modulation of retinoid acid signaling, and thiamine deficiency. The endoplasmic reticulum (ER) regulates posttranslational protein processing and transport. The accumulation of unfolded or misfolded proteins in the ER lumen triggers ER stress and induces unfolded protein response (UPR) which are mediated by three transmembrane ER signaling proteins: pancreatic endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), and activating transcription factor 6 (ATF6). UPR is initiated to protect cells from overwhelming ER protein loading. However, sustained ER stress may result in cell death. ER stress has been implied in various CNS injuries, including brain ischemia, traumatic brain injury, and aging-associated neurodegeneration, such as Alzheimer's disease (AD), Huntington's disease (HD), Amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). However, effects of ethanol on ER stress in the CNS receive less attention. In this review, we discuss recent progress in the study of ER stress in ethanol-induced neurotoxicity. We also examine the potential mechanisms underlying ethanol-mediated ER stress and the interaction among ER stress, oxidative stress and autophagy in the context of ethanol neurotoxicity.

  14. Endoplasmic Reticulum Stress and Ethanol Neurotoxicity

    PubMed Central

    Yang, Fanmuyi; Luo, Jia

    2015-01-01

    Ethanol abuse affects virtually all organ systems and the central nervous system (CNS) is particularly vulnerable to excessive ethanol exposure. Ethanol exposure causes profound damages to both the adult and developing brain. Prenatal ethanol exposure induces fetal alcohol spectrum disorders (FASD) which is associated with mental retardation and other behavioral deficits. A number of potential mechanisms have been proposed for ethanol-induced brain damage; these include the promotion of neuroinflammation, interference with signaling by neurotrophic factors, induction of oxidative stress, modulation of retinoid acid signaling, and thiamine deficiency. The endoplasmic reticulum (ER) regulates posttranslational protein processing and transport. The accumulation of unfolded or misfolded proteins in the ER lumen triggers ER stress and induces unfolded protein response (UPR) which are mediated by three transmembrane ER signaling proteins: pancreatic endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1 (IRE1), and activating transcription factor 6 (ATF6). UPR is initiated to protect cells from overwhelming ER protein loading. However, sustained ER stress may result in cell death. ER stress has been implied in various CNS injuries, including brain ischemia, traumatic brain injury, and aging-associated neurodegeneration, such as Alzheimer’s disease (AD), Huntington’s disease (HD), Amyotrophic lateral sclerosis (ALS), and Parkinson’s disease (PD). However, effects of ethanol on ER stress in the CNS receive less attention. In this review, we discuss recent progress in the study of ER stress in ethanol-induced neurotoxicity. We also examine the potential mechanisms underlying ethanol-mediated ER stress and the interaction among ER stress, oxidative stress and autophagy in the context of ethanol neurotoxicity. PMID:26473940

  15. Photoelectrochemical water splitting and simultaneous photoelectrocatalytic degradation of organic pollutant on highly smooth and ordered TiO{sub 2} nanotube arrays

    SciTech Connect

    Wu Hongjun; Zhang Zhonghai

    2011-12-15

    The photoelectrochemical water splitting and simultaneous photoelectrocatalytic degradation of organic pollutant were achieved on TiO{sub 2} nanotube electrodes with double purposes of environmental protection and renewable energy production under illumination of simulated solar light. The TiO{sub 2} nanotube arrays (TiO{sub 2} NTs) were fabricated by a two-step anodization method. The TiO{sub 2} NTs prepared in two-step anodization process (2-step TiO{sub 2} NTs) showed much better surface smoothness and tube orderliness than TiO{sub 2} NTs prepared in one-step anodization process (1-step TiO{sub 2} NTs). In the photoelectrochemical water splitting and simultaneous photoelectrocatalytic decomposition process, the 2-step TiO{sub 2} NTs electrode showed both highest photo-conversion efficiency of 1.25% and effective photodecomposition efficiency with existing of methylene blue (MB) as sacrificial agent and as pollutant target. Those results implied that the highly ordered nanostructures provided direct pathway and uniform electric field distribution for effective charges transfer, as well as superior capabilities of light harvesting. - Graphical Abstract: The photoelectrochemical water splitting for hydrogen generation and simultaneous photoelectrocatalytic degradation of organic pollutant (methylene blue) were achieved on TiO{sub 2} nanotube electrodes with double purposes of environmental protection and renewable energy production under illumination of simulated solar light. Highlights: Black-Right-Pointing-Pointer TiO{sub 2} nanotube arrays were fabricated by a two-step anodization method. Black-Right-Pointing-Pointer Hydrogen generation and organic pollutant degradation were achieved on TiO{sub 2} NTs. Black-Right-Pointing-Pointer Highest photoconversion efficiency of 1.25% was achieved. Black-Right-Pointing-Pointer Increasing orderliness will increase photocatalytic activity of TiO{sub 2} NTs.

  16. Brain endoplasmic reticulum stress mechanistically distinguishes the saline-intake and hypertensive response to deoxycorticosterone acetate-salt.

    PubMed

    Jo, Fusakazu; Jo, Hiromi; Hilzendeger, Aline M; Thompson, Anthony P; Cassell, Martin D; Rutkowski, D Thomas; Davisson, Robin L; Grobe, Justin L; Sigmund, Curt D

    2015-06-01

    Endoplasmic reticulum stress has become an important mechanism in hypertension. We examined the role of endoplasmic reticulum stress in mediating the increased saline-intake and hypertensive effects in response to deoxycorticosterone acetate (DOCA)-salt. Intracerebroventricular delivery of the endoplasmic reticulum stress-reducing chemical chaperone tauroursodeoxycholic acid did not affect the magnitude of hypertension, but markedly decreased saline-intake in response to DOCA-salt. Increased saline-intake returned after tauroursodeoxycholic acid was terminated. Decreased saline-intake was also observed after intracerebroventricular infusion of 4-phenylbutyrate, another chemical chaperone. Immunoreactivity to CCAAT homologous binding protein, a marker of irremediable endoplasmic reticulum stress, was increased in the subfornical organ and supraoptic nucleus of DOCA-salt mice, but the signal was absent in control and CCAAT homologous binding protein-deficient mice. Electron microscopy revealed abnormalities in endoplasmic reticulum structure (decrease in membrane length, swollen membranes, and decreased ribosome numbers) in the subfornical organ consistent with endoplasmic reticulum stress. Subfornical organ-targeted adenoviral delivery of GRP78, a resident endoplasmic reticulum chaperone, decreased DOCA-salt-induced saline-intake. The increase in saline-intake in response to DOCA-salt was blunted in CCAAT homologous binding protein-deficient mice, but these mice exhibited a normal hypertensive response. We conclude that (1) brain endoplasmic reticulum stress mediates the saline-intake, but not blood pressure response to DOCA-salt, (2) DOCA-salt causes endoplasmic reticulum stress in the subfornical organ, which when attenuated by GRP78 blunts saline-intake, and (3) CCAAT homologous binding protein may play a functional role in DOCA-salt-induced saline-intake. The results suggest a mechanistic distinction between the importance of endoplasmic reticulum stress in

  17. Role of p97 and Syntaxin 5 in the Assembly of Transitional Endoplasmic Reticulum

    PubMed Central

    Roy, Line; Bergeron, John J.M.; Lavoie, Christine; Hendriks, Rob; Gushue, Jennifer; Fazel, Ali; Pelletier, Amélie; Morré, D. James; Subramaniam, V. Nathan; Hong, Wanjin; Paiement, Jacques

    2000-01-01

    Transitional endoplasmic reticulum (tER) consists of confluent rough and smooth endoplasmic reticulum (ER) domains. In a cell-free incubation system, low-density microsomes (1.17 g cc−1) isolated from rat liver homogenates reconstitute tER by Mg2+GTP- and Mg2+ATP-hydrolysis–dependent membrane fusion. The ATPases associated with different cellular activities protein p97 has been identified as the relevant ATPase. The ATP depletion by hexokinase or treatment with either N-ethylmaleimide or anti-p97 prevented assembly of the smooth ER domain of tER. High-salt washing of low-density microsomes inhibited assembly of the smooth ER domain of tER, whereas the readdition of purified p97 with associated p47 promoted reconstitution. The t-SNARE syntaxin 5 was observed within the smooth ER domain of tER, and antisyntaxin 5 abrogated formation of this same membrane compartment. Thus, p97 and syntaxin 5 regulate assembly of the smooth ER domain of tER and hence one of the earliest membrane differentiated components of the secretory pathway. PMID:10930451

  18. Terasaki Spiral Ramps in the Rough Endoplasmic Reticulum

    NASA Astrophysics Data System (ADS)

    Guven, Jemal; Huber, Greg; Valencia, Dulce María

    2014-10-01

    We present a model describing the morphology as well as the assembly of "Terasaki ramps," the recently discovered helicoidal connections linking adjacent sheets of the rough endoplasmic reticulum (ER). The fundamental unit is a localized symmetric double-ramped "parking garage" formed by two separated gently pitched, approximately helicoidal, ramps of opposite chiralities. This geometry is stabilized by a short-range repulsive interaction between ramps associated with bending energy which opposes the long-range attraction associated with tension. The ramp inner boundaries are themselves stabilized by the condensation of membrane-shaping proteins along their length. A mechanism for parking garage self-assembly is proposed involving the nucleation of dipoles at the center of tubular three-way junctions within the smooth ER. Our predictions are compared with the experimental data.

  19. Terasaki spiral ramps in the rough endoplasmic reticulum.

    PubMed

    Guven, Jemal; Huber, Greg; Valencia, Dulce María

    2014-10-31

    We present a model describing the morphology as well as the assembly of "Terasaki ramps," the recently discovered helicoidal connections linking adjacent sheets of the rough endoplasmic reticulum (ER). The fundamental unit is a localized symmetric double-ramped "parking garage" formed by two separated gently pitched, approximately helicoidal, ramps of opposite chiralities. This geometry is stabilized by a short-range repulsive interaction between ramps associated with bending energy which opposes the long-range attraction associated with tension. The ramp inner boundaries are themselves stabilized by the condensation of membrane-shaping proteins along their length. A mechanism for parking garage self-assembly is proposed involving the nucleation of dipoles at the center of tubular three-way junctions within the smooth ER. Our predictions are compared with the experimental data.

  20. Studies on the Endoplasmic Reticulum

    PubMed Central

    Porter, Keith R.; Machado, Raul D.

    1960-01-01

    Cells of onion and garlic root tips were examined under the electron and phase contrast microscopes after fixation in KMnO4. Special attention was focused on the distribution and behavior of the endoplasmic reticulum (ER) during the several phases of mitosis. Slender profiles, recognized as sections through thin lamellar units of the ER (most prominent in KMnO4-fixed material), are distributed more or less uniformly in the cytoplasm of interphase cells and show occasional continuity with the nuclear envelope. In late prophase the nuclear envelope breaks down and its remnants plus cytoplasmic elements of the ER, which are morphologically identical, surround the spindle in a zone from which mitochondria, etc., are excluded. During metaphase these ER elements persist and concentrate as two separate systems in the polar caps or zones of the spindle. At about this same time they begin to proliferate and to invade the ends of the spindle. The invading lamellar units form drape-like partitions between the anaphase chromosomes. In late anaphase, their advancing margins reach the middle zone of the spindle and begin to fray out. Finally, in telophase, while elements of the ER in the poles of the spindle coalesce around the chromosomes to form the new envelope, the advancing edges of those in the middle zone reticulate at the level of the equator to form a close lattice of tubular elements. Within this, which is identified as the phragmoplast, the earliest signs of the cell plate appear in the form of small vesicles. These subsequently grow and fuse to complete the separation of the two protoplasts. Other morphological units apparently participating in mitosis are described. Speculation is provided on the equal division or not of the nuclear envelope and the contribution the envelope fragments make to the ER of the new cell. PMID:14434278

  1. Potassium fluxes across the endoplasmic reticulum and their role in endoplasmic reticulum calcium homeostasis.

    PubMed

    Kuum, Malle; Veksler, Vladimir; Kaasik, Allen

    2015-07-01

    There are a number of known and suspected channels and exchangers in the endoplasmic reticulum that may participate in potassium flux across its membrane. They include trimeric intracellular cation channels permeable for potassium, ATP-sensitive potassium channels, calcium-activated potassium channels and the potassium-hydrogen exchanger. Apart from trimeric intracellular cation channels, which are specific to the endoplasmic reticulum, other potassium channels are also expressed in the plasma membrane and/or mitochondria, and their specific role in the endoplasmic reticulum has not yet been fully established. In addition to these potassium-selective channels, the ryanodine receptor and, potentially, the inositol 1,4,5-trisphosphate receptor are permeable to potassium ions. Also, the role of potassium fluxes across the endoplasmic reticulum membrane has remained elusive. It has been proposed that their main role is to balance the charge movement that occurs during calcium release and uptake from or to the endoplasmic reticulum. This review aims to summarize current knowledge on endoplasmic reticulum potassium channels and fluxes and their potential role in endoplasmic reticulum calcium uptake and release.

  2. Generalized smooth models

    SciTech Connect

    Glosup, J.

    1992-07-23

    The class of gene linear models is extended to develop a class of nonparametric regression models known as generalized smooth models. The technique of local scoring is used to estimate a generalized smooth model and the estimation procedure based on locally weighted regression is shown to produce local likelihood estimates. The asymptotically correct distribution of the deviance difference is derived and its use in comparing the fits of generalized linear models and generalized smooth models is illustrated. The relationship between generalized smooth models and generalized additive models is discussed, also.

  3. Endoplasmic reticulum aminopeptidases: biochemistry, physiology and pathology.

    PubMed

    Hattori, Akira; Tsujimoto, Masafumi

    2013-09-01

    The human endoplasmic reticulum aminopeptidase (ERAP) 1 and 2 proteins were initially identified as homologues of human placental leucine aminopeptidase/insulin-regulated aminopeptidase. They are categorized as a unique class of proteases based on their subcellular localization on the luminal side of the endoplasmic reticulum. ERAPs play an important role in the N-terminal processing of the antigenic precursors that are presented on the major histocompatibility complex (MHC) class I molecules. ERAPs are also implicated in the regulation of a wide variety of physiological phenomena and pathogenic conditions. In this review, the current knowledge on ERAPs is summarized.

  4. SMOOTH MUSCLE STEM CELLS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vascular smooth muscle cells (SMCs) originate from multiple types of progenitor cells. In the embryo, the most well-studied SMC progenitor is the cardiac neural crest stem cell. Smooth muscle differentiation in the neural crest lineage is controlled by a combination of cell intrinsic factors, includ...

  5. Diamond Smoothing Tools

    NASA Technical Reports Server (NTRS)

    Voronov, Oleg

    2007-01-01

    Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors. A diamond smoothing tool according to the proposal would have a smooth spherical surface. For a given finish machining operation, the smoothing tool would be mounted next to the cutting tool. The smoothing tool would slide on the machined surface left behind by the cutting tool, plastically deforming the surface material and thereby reducing the roughness of the surface, closing microcracks and otherwise generally reducing or eliminating microscopic surface and subsurface defects, and increasing the microhardness of the surface layer. It has been estimated that if smoothing tools of this type were used in conjunction with cutting tools on sufficiently precise lathes, it would be possible to reduce the roughness of machined surfaces to as little as 3 nm. A tool according to the proposal would consist of a smoothing insert in a metal holder. The smoothing insert would be made from a diamond/metal functionally graded composite rod preform, which, in turn, would be made by sintering together a bulk single-crystal or polycrystalline diamond, a diamond powder, and a metallic alloy at high pressure. To form the spherical smoothing tip, the diamond end of the preform would be subjected to flat grinding, conical grinding, spherical grinding using diamond wheels, and finally spherical polishing and/or buffing using diamond powders. If the diamond were a single crystal, then it would be crystallographically oriented, relative to the machining motion, to minimize its wear and maximize its hardness. Spherically polished diamonds could also be useful for purposes other than smoothing in finish machining: They would likely also be suitable for use as heat-resistant, wear-resistant, unlubricated sliding-fit bearing inserts.

  6. Peptidyl prolyl cis-trans-isomerase activity associated with the lumen of the endoplasmic reticulum.

    PubMed Central

    Bose, S; Freedman, R B

    1994-01-01

    Peptidyl prolyl cis-trans-isomerase (PPI) activity was detected in microsomal fractions from bovine and rat liver. Extensive washing, proteinase and sonication treatments indicated that although some of this activity was due to adsorbed cytosolic enzymes, there was also an active but latent microsomal PPI activity. Density-gradient subfractionation indicated that activity was associated with vesicles derived from both the rough and the smooth endoplasmic reticulum (ER), suggesting that the activity was located within the ER lumen. The luminal PPI activity was inhibited by cyclosporin A and was active towards an unfolded protein substrate as well as towards the standard peptide substrate. PMID:8010971

  7. Targeting of OSBP-related protein 3 (ORP3) to endoplasmic reticulum and plasma membrane is controlled by multiple determinants

    SciTech Connect

    Lehto, Markku; Hynynen, Riikka; Karjalainen, Katja; Kuismanen, Esa; Hyvaerinen, Kati; Olkkonen, Vesa M. . E-mail: vesa.olkkonen@ktl.fi

    2005-11-01

    The intracellular targeting determinants of oxysterol binding protein (OSBP)-related protein 3 (ORP3) were studied using a series of truncated and point mutated constructs. The pleckstrin homology (PH) domain of ORP3 binds the phosphoinositide-3-kinase (PI3K) products, PI(3,4)P{sub 2} and PI(3,4,5)P{sub 3}. A functional PH domain and flanking sequences are crucial for the plasma membrane (PM) targeting of ORP3. The endoplasmic reticulum (ER) targeting of ORP3 is regulated the by a FFAT motif (EFFDAxE), which mediates interaction with VAMP-associated protein (VAP)-A. The targeting function of the FFAT motif dominates over that of the PH domain. In addition, the exon 10/11 region modulates interaction of ORP3 with the ER and the nuclear membrane. Analysis of a chimeric ORP3:OSBP protein suggests that ligand binding by the C-terminal domain of OSBP induces allosteric changes that activate the N-terminal targeting modules of ORP3. Notably, over-expression of ORP3 together with VAP-A induces stacked ER membrane structures also known as organized smooth ER (OSER). Moreover, lipid starvation promotes formation of dilated peripheral ER (DPER) structures dependent on the ORP3 protein. Based on the present data, we introduce a model for the inter-relationships of the functional domains of ORP3 in the membrane targeting of the protein.

  8. Discrete square root smoothing.

    NASA Technical Reports Server (NTRS)

    Kaminski, P. G.; Bryson, A. E., Jr.

    1972-01-01

    The basic techniques applied in the square root least squares and square root filtering solutions are applied to the smoothing problem. Both conventional and square root solutions are obtained by computing the filtered solutions, then modifying the results to include the effect of all measurements. A comparison of computation requirements indicates that the square root information smoother (SRIS) is more efficient than conventional solutions in a large class of fixed interval smoothing problems.

  9. Endoplasmic Reticulum Stress and Associated ROS

    PubMed Central

    Zeeshan, Hafiz Maher Ali; Lee, Geum Hwa; Kim, Hyung-Ryong; Chae, Han-Jung

    2016-01-01

    The endoplasmic reticulum (ER) is a fascinating network of tubules through which secretory and transmembrane proteins enter unfolded and exit as either folded or misfolded proteins, after which they are directed either toward other organelles or to degradation, respectively. The ER redox environment dictates the fate of entering proteins, and the level of redox signaling mediators modulates the level of reactive oxygen species (ROS). Accumulating evidence suggests the interrelation of ER stress and ROS with redox signaling mediators such as protein disulfide isomerase (PDI)-endoplasmic reticulum oxidoreductin (ERO)-1, glutathione (GSH)/glutathione disuphide (GSSG), NADPH oxidase 4 (Nox4), NADPH-P450 reductase (NPR), and calcium. Here, we reviewed persistent ER stress and protein misfolding-initiated ROS cascades and their significant roles in the pathogenesis of multiple human disorders, including neurodegenerative diseases, diabetes mellitus, atherosclerosis, inflammation, ischemia, and kidney and liver diseases. PMID:26950115

  10. Quantitative proteomic survey of endoplasmic reticulum in mouse liver.

    PubMed

    Song, Yanping; Jiang, Ying; Ying, Wantao; Gong, Yan; Yan, Yujuan; Yang, Dong; Ma, Jie; Xue, Xiaofang; Zhong, Fan; Wu, Songfeng; Hao, Yunwei; Sun, Aihua; Li, Tao; Sun, Wei; Wei, Handong; Zhu, Yunping; Qian, Xiaohong; He, Fuchu

    2010-03-01

    To gain a better understanding of the critical function of the endoplasmic reticulum (ER) in liver, we carried out a proteomic survey of mouse liver ER. The ER proteome was profiled with a new three-dimensional, gel-based strategy. From 6152 and 6935 MS spectra, 903 and 1042 proteins were identified with at least two peptides matches at 95% confidence in the rough (r) and smooth (s) ER, respectively. Comparison of the rER and sER proteomes showed that calcium-binding proteins are significantly enriched in the sER suggesting that the ion-binding function of the ER is compartmentalized. Comparison of the rat and mouse ER proteomes showed that 662 proteins were common to both, comprising 53.5% and 49.3% of those proteomes, respectively. We proposed that these proteins were stably expressed proteins that were essential for the maintenance of ER function. GO annotation with a hypergeometric model proved this hypothesis. Unexpectedly, 210 unknown proteins and some proteins previously reported to occur in the cytosol were highly enriched in the ER. This study provides a reference map for the ER proteome of liver. Identification of new ER proteins will enhance our current understanding of the ER and also suggest new functions for this organelle.

  11. The endoplasmic reticulum: a social network in plant cells.

    PubMed

    Chen, Jun; Doyle, Caitlin; Qi, Xingyun; Zheng, Huanquan

    2012-11-01

    The endoplasmic reticulum (ER) is an interconnected network comprised of ribosome-studded sheets and smooth tubules. The ER plays crucial roles in the biosynthesis and transport of proteins and lipids, and in calcium (Ca(2+) ) regulation in compartmentalized eukaryotic cells including plant cells. To support its well-segregated functions, the shape of the ER undergoes notable changes in response to both developmental cues and outside influences. In this review, we will discuss recent findings on molecular mechanisms underlying the unique morphology and dynamics of the ER, and the importance of the interconnected ER network in cell polarity. In animal and yeast cells, two family proteins, the reticulons and DP1/Yop1, are required for shaping high-curvature ER tubules, while members of the atlastin family of dynamin-like GTPases are involved in the fusion of ER tubules to make an interconnected ER network. In plant cells, recent data also indicate that the reticulons are involved in shaping ER tubules, while RHD3, a plant member of the atlastin GTPases, is required for the generation of an interconnected ER network. We will also summarize the current knowledge on how the ER interacts with other membrane-bound organelles, with a focus on how the ER and Golgi interplay in plant cells. PMID:23046093

  12. The endoplasmic reticulum: structure, function and response to cellular signaling.

    PubMed

    Schwarz, Dianne S; Blower, Michael D

    2016-01-01

    The endoplasmic reticulum (ER) is a large, dynamic structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. The diverse functions of the ER are performed by distinct domains; consisting of tubules, sheets and the nuclear envelope. Several proteins that contribute to the overall architecture and dynamics of the ER have been identified, but many questions remain as to how the ER changes shape in response to cellular cues, cell type, cell cycle state and during development of the organism. Here we discuss what is known about the dynamics of the ER, what questions remain, and how coordinated responses add to the layers of regulation in this dynamic organelle. PMID:26433683

  13. Pharmacological Modulators of Endoplasmic Reticulum Stress in Metabolic Diseases

    PubMed Central

    Jung, Tae Woo; Choi, Kyung Mook

    2016-01-01

    The endoplasmic reticulum (ER) is the principal organelle responsible for correct protein folding, a step in protein synthesis that is critical for the functional conformation of proteins. ER stress is a primary feature of secretory cells and is involved in the pathogenesis of numerous human diseases, such as certain neurodegenerative and cardiometabolic disorders. The unfolded protein response (UPR) is a defense mechanism to attenuate ER stress and maintain the homeostasis of the organism. Two major degradation systems, including the proteasome and autophagy, are involved in this defense system. If ER stress overwhelms the capacity of the cell’s defense mechanisms, apoptotic death may result. This review is focused on the various pharmacological modulators that can protect cells from damage induced by ER stress. The possible mechanisms for cytoprotection are also discussed. PMID:26840310

  14. Proliferation and Morphogenesis of the Endoplasmic Reticulum Driven by the Membrane Domain of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase in Plant Cells.

    PubMed

    Ferrero, Sergi; Grados-Torrez, Ricardo Enrique; Leivar, Pablo; Antolín-Llovera, Meritxell; López-Iglesias, Carmen; Cortadellas, Nuria; Ferrer, Joan Carles; Campos, Narciso

    2015-07-01

    The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) has a key regulatory role in the mevalonate pathway for isoprenoid biosynthesis and is composed of an endoplasmic reticulum (ER)-anchoring membrane domain with low sequence similarity among eukaryotic kingdoms and a conserved cytosolic catalytic domain. Organized smooth endoplasmic reticulum (OSER) structures are common formations of hypertrophied tightly packed ER membranes devoted to specific biosynthetic and secretory functions, the biogenesis of which remains largely unexplored. We show that the membrane domain of plant HMGR suffices to trigger ER proliferation and OSER biogenesis. The proliferating membranes become highly enriched in HMGR protein, but they do not accumulate sterols, indicating a morphogenetic rather than a metabolic role for HMGR. The N-terminal MDVRRRPP motif present in most plant HMGR isoforms is not required for retention in the ER, which was previously proposed, but functions as an ER morphogenic signal. Plant OSER structures are morphologically similar to those of animal cells, emerge from tripartite ER junctions, and mainly build up beside the nuclear envelope, indicating conserved OSER biogenesis in high eukaryotes. Factors other than the OSER-inducing HMGR construct mediate the tight apposition of the proliferating membranes, implying separate ER proliferation and membrane association steps. Overexpression of the membrane domain of Arabidopsis (Arabidopsis thaliana) HMGR leads to ER hypertrophy in every tested cell type and plant species, whereas the knockout of the HMG1 gene from Arabidopsis, encoding its major HMGR isoform, causes ER aggregation at the nuclear envelope. Our results show that the membrane domain of HMGR contributes to ER morphogenesis in plant cells.

  15. Proliferation and Morphogenesis of the Endoplasmic Reticulum Driven by the Membrane Domain of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase in Plant Cells1[OPEN

    PubMed Central

    Ferrero, Sergi; Grados-Torrez, Ricardo Enrique; Antolín-Llovera, Meritxell; López-Iglesias, Carmen; Cortadellas, Nuria; Ferrer, Joan Carles

    2015-01-01

    The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) has a key regulatory role in the mevalonate pathway for isoprenoid biosynthesis and is composed of an endoplasmic reticulum (ER)-anchoring membrane domain with low sequence similarity among eukaryotic kingdoms and a conserved cytosolic catalytic domain. Organized smooth endoplasmic reticulum (OSER) structures are common formations of hypertrophied tightly packed ER membranes devoted to specific biosynthetic and secretory functions, the biogenesis of which remains largely unexplored. We show that the membrane domain of plant HMGR suffices to trigger ER proliferation and OSER biogenesis. The proliferating membranes become highly enriched in HMGR protein, but they do not accumulate sterols, indicating a morphogenetic rather than a metabolic role for HMGR. The N-terminal MDVRRRPP motif present in most plant HMGR isoforms is not required for retention in the ER, which was previously proposed, but functions as an ER morphogenic signal. Plant OSER structures are morphologically similar to those of animal cells, emerge from tripartite ER junctions, and mainly build up beside the nuclear envelope, indicating conserved OSER biogenesis in high eukaryotes. Factors other than the OSER-inducing HMGR construct mediate the tight apposition of the proliferating membranes, implying separate ER proliferation and membrane association steps. Overexpression of the membrane domain of Arabidopsis (Arabidopsis thaliana) HMGR leads to ER hypertrophy in every tested cell type and plant species, whereas the knockout of the HMG1 gene from Arabidopsis, encoding its major HMGR isoform, causes ER aggregation at the nuclear envelope. Our results show that the membrane domain of HMGR contributes to ER morphogenesis in plant cells. PMID:26015445

  16. Protein Translocation across the Rough Endoplasmic Reticulum

    PubMed Central

    Mandon, Elisabet C.; Trueman, Steven F.; Gilmore, Reid

    2013-01-01

    The rough endoplasmic reticulum is a major site of protein biosynthesis in all eukaryotic cells, serving as the entry point for the secretory pathway and as the initial integration site for the majority of cellular integral membrane proteins. The core components of the protein translocation machinery have been identified, and high-resolution structures of the targeting components and the transport channel have been obtained. Research in this area is now focused on obtaining a better understanding of the molecular mechanism of protein translocation and membrane protein integration. PMID:23251026

  17. A monoclonal antibody against alpha-smooth muscle actin: a new probe for smooth muscle differentiation

    PubMed Central

    1986-01-01

    A monoclonal antibody (anti-alpha sm-1) recognizing exclusively alpha- smooth muscle actin was selected and characterized after immunization of BALB/c mice with the NH2-terminal synthetic decapeptide of alpha- smooth muscle actin coupled to keyhole limpet hemocyanin. Anti-alpha sm- 1 helped in distinguishing smooth muscle cells from fibroblasts in mixed cultures such as rat dermal fibroblasts and chicken embryo fibroblasts. In the aortic media, it recognized a hitherto unknown population of cells negative for alpha-smooth muscle actin and for desmin. In 5-d-old rats, this population is about half of the medial cells and becomes only 8 +/- 5% in 6-wk-old animals. In cultures of rat aortic media SMCs, there is a progressive increase of this cell population together with a progressive decrease in the number of alpha- smooth muscle actin-containing stress fibers per cell. Double immunofluorescent studies carried out with anti-alpha sm-1 and anti- desmin antibodies in several organs revealed a heterogeneity of stromal cells. Desmin-negative, alpha-smooth muscle actin-positive cells were found in the rat intestinal muscularis mucosae and in the dermis around hair follicles. Moreover, desmin-positive, alpha-smooth muscle actin- negative cells were identified in the intestinal submucosa, rat testis interstitium, and uterine stroma. alpha-Smooth muscle actin was also found in myoepithelial cells of mammary and salivary glands, which are known to express cytokeratins. Finally, alpha-smooth muscle actin is present in stromal cells of mammary carcinomas, previously considered fibroblastic in nature. Thus, anti-alpha sm-1 antibody appears to be a powerful probe in the study of smooth muscle differentiation in normal and pathological conditions. PMID:3539945

  18. Globular adiponectin reduces vascular calcification via inhibition of ER-stress-mediated smooth muscle cell apoptosis

    PubMed Central

    Lu, Yan; Bian, Yunfei; Wang, Yueru; Bai, Rui; Wang, Jiapu; Xiao, Chuanshi

    2015-01-01

    Objective: This study aims to explore the mechanism of globular adiponectin inhibiting vascular calcification. Methods: We established drug-induced rat vascular calcification model, globular adiponectin was given to observe the effect of globular Adiponectin on the degree of calcification. The markers of vascular calcification and apoptosis were also investigated. Meanwhile, the in vitro effect of globular Adiponectin on vascular calcification was also evaluated using primary cultured rat vascular smooth muscle cells. Results: We found that globular adiponectin could inhibit drug-induced rat vascular calcification significantly in vivo. The apoptosis of vascular smooth muscle cells was also reduced. The possible mechanism could be the down-regulation of endoplasmic reticulum stress by globular adiponectin. Experiments in primary cultured vascular smooth muscle cells also confirmed that globular adiponectin could reduce cell apoptosis to suppress vascular calcification via inhibition of endoplasmic reticulum stress. Conclusions: This study confirmed that globular adiponectin could suppress vascular calcification; one of the mechanisms could be inhibition of endoplasmic reticulum stress to reduce cell apoptosis. It could provide an effective method in the therapy of vascular calcification-associated diseases. PMID:26045760

  19. Anti-smooth muscle antibody

    MedlinePlus

    ... medlineplus.gov/ency/article/003531.htm Anti-smooth muscle antibody To use the sharing features on this page, please enable JavaScript. Anti-smooth muscle antibody is a blood test that detects the ...

  20. Effects of hydrogen sulphide in smooth muscle.

    PubMed

    Dunn, William R; Alexander, Stephen P H; Ralevic, Vera; Roberts, Richard E

    2016-02-01

    In recent years, it has become apparent that the gaseous pollutant, hydrogen sulphide (H2S) can be synthesised in the body and has a multitude of biological actions. This review summarizes some of the actions of this 'gasotransmitter' in influencing the smooth muscle that is responsible for controlling muscular activity of hollow organs. In the vasculature, while H2S can cause vasoconstriction by complex interactions with other biologically important gases, such as nitric oxide, the prevailing response is vasorelaxation. While most vasorelaxation responses occur by a direct action of H2S on smooth muscle cells, it has recently been proposed to be an endothelium-derived hyperpolarizing factor. H2S also promotes relaxation in other smooth muscle preparations including bronchioles, the bladder, gastrointestinal tract and myometrium, opening up the opportunity of exploiting the pharmacology of H2S in the treatment of conditions where smooth muscle tone is excessive. The original concept, that H2S caused smooth muscle relaxation by activating ATP-sensitive K(+) channels, has been supplemented with observations that H2S can also modify the activity of other potassium channels, intracellular pH, phosphodiesterase activity and transient receptor potential channels on sensory nerves. While the enzymes responsible for generating endogenous H2S are widely expressed in smooth muscle preparations, it is much less clear what the physiological role of H2S is in determining smooth muscle contractility. Clarification of this requires the development of potent and selective inhibitors of H2S-generating enzymes.

  1. Membrane Protein Insertion at the Endoplasmic Reticulum

    PubMed Central

    Shao, Sichen; Hegde, Ramanujan S.

    2014-01-01

    Integral membrane proteins of the cell surface and most intracellular compartments of eukaryotic cells are assembled at the endoplasmic reticulum. Two highly conserved and parallel pathways mediate membrane protein targeting to and insertion into this organelle. The classical cotranslational pathway, utilized by most membrane proteins, involves targeting by the signal recognition particle followed by insertion via the Sec61 translocon. A more specialized posttranslational pathway, employed by many tail-anchored membrane proteins, is composed of entirely different factors centered around a cytosolic ATPase termed TRC40 or Get3. Both of these pathways overcome the same biophysical challenges of ferrying hydrophobic cargo through an aqueous milieu, selectively delivering it to one among several intracellular membranes and asymmetrically integrating its transmembrane domain(s) into the lipid bilayer. Here, we review the conceptual and mechanistic themes underlying these core membrane protein insertion pathways, the complexities that challenge our understanding, and future directions to over-come these obstacles. PMID:21801011

  2. Endoplasmic-Reticulum Calcium Depletion and Disease

    PubMed Central

    Mekahli, Djalila; Bultynck, Geert; Parys, Jan B.; De Smedt, Humbert; Missiaen, Ludwig

    2011-01-01

    The endoplasmic reticulum (ER) as an intracellular Ca2+ store not only sets up cytosolic Ca2+ signals, but, among other functions, also assembles and folds newly synthesized proteins. Alterations in ER homeostasis, including severe Ca2+ depletion, are an upstream event in the pathophysiology of many diseases. On the one hand, insufficient release of activator Ca2+ may no longer sustain essential cell functions. On the other hand, loss of luminal Ca2+ causes ER stress and activates an unfolded protein response, which, depending on the duration and severity of the stress, can reestablish normal ER function or lead to cell death. We will review these various diseases by mainly focusing on the mechanisms that cause ER Ca2+ depletion. PMID:21441595

  3. Endoplasmic reticulum stress responses in plants.

    PubMed

    Howell, Stephen H

    2013-01-01

    Endoplasmic reticulum (ER) stress is of considerable interest to plant biologists because it occurs in plants subjected to adverse environmental conditions. ER stress responses mitigate the damage caused by stress and confer levels of stress tolerance to plants. ER stress is activated by misfolded proteins that accumulate in the ER under adverse environmental conditions. Under these conditions, the demand for protein folding exceeds the capacity of the system, which sets off the unfolded protein response (UPR). Two arms of the UPR signaling pathway have been described in plants: one that involves two ER membrane-associated transcription factors (bZIP17 and bZIP28) and another that involves a dual protein kinase (RNA-splicing factor IRE1) and its target RNA (bZIP60). Under mild or short-term stress conditions, signaling from IRE1 activates autophagy, a cell survival response. But under severe or chronic stress conditions, ER stress can lead to cell death.

  4. Endoplasmic reticulum: ER stress regulates mitochondrial bioenergetics.

    PubMed

    Bravo, Roberto; Gutierrez, Tomás; Paredes, Felipe; Gatica, Damián; Rodriguez, Andrea E; Pedrozo, Zully; Chiong, Mario; Parra, Valentina; Quest, Andrew F G; Rothermel, Beverly A; Lavandero, Sergio

    2012-01-01

    Endoplasmic reticulum (ER) stress activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. The molecular mechanisms responsible for execution of the cell death program are relatively well characterized, but the metabolic events taking place during the adaptive phase of ER stress remain largely undefined. Here we discuss emerging evidence regarding the metabolic changes that occur during the onset of ER stress and how ER influences mitochondrial function through mechanisms involving calcium transfer, thereby facilitating cellular adaptation. Finally, we highlight how dysregulation of ER-mitochondrial calcium homeostasis during prolonged ER stress is emerging as a novel mechanism implicated in the onset of metabolic disorders. PMID:22064245

  5. Endoplasmic Reticulum Stress and Type 2 Diabetes

    PubMed Central

    Back, Sung Hoon; Kaufman, Randal J.

    2013-01-01

    Given the functional importance of the endoplasmic reticulum (ER), an organelle that performs folding, modification, and trafficking of secretory and membrane proteins to the Golgi compartment, the maintenance of ER homeostasis in insulin-secreting β-cells is very important. When ER homeostasis is disrupted, the ER generates adaptive signaling pathways, called the unfolded protein response (UPR), to maintain homeostasis of this organelle. However, if homeostasis fails to be restored, the ER initiates death signaling pathways. New observations suggest that both chronic hyperglycemia and hyperlipidemia, known as important causative factors of type 2 diabetes (T2D), disrupt ER homeostasis to induce unresolvable UPR activation and β-cell death. This review examines how the UPR pathways, induced by high glucose and free fatty acids (FFAs), interact to disrupt ER function and cause β-cell dysfunction and death. PMID:22443930

  6. Nonvesicular Lipid Transfer from the Endoplasmic Reticulum

    PubMed Central

    Lev, Sima

    2012-01-01

    The transport of lipids from their synthesis site at the endoplasmic reticulum (ER) to different target membranes could be mediated by both vesicular and nonvesicular transport mechanisms. Nonvesicular lipid transport appears to be the major transport route of certain lipid species, and could be mediated by either spontaneous lipid transport or by lipid-transfer proteins (LTPs). Although nonvesicular lipid transport has been extensively studied for more than four decades, its underlying mechanism, advantage and regulation, have not been fully explored. In particular, the function of LTPs and their involvement in intracellular lipid movement remain largely controversial. In this article, we describe the pathways by which lipids are synthesized at the ER and delivered to different cellular membranes, and discuss the role of LTPs in lipid transport both in vitro and in intact cells. PMID:23028121

  7. The Pathogen-Occupied Vacuoles of Anaplasma phagocytophilum and Anaplasma marginale Interact with the Endoplasmic Reticulum.

    PubMed

    Truchan, Hilary K; Cockburn, Chelsea L; Hebert, Kathryn S; Magunda, Forgivemore; Noh, Susan M; Carlyon, Jason A

    2016-01-01

    The genus Anaplasma consists of tick-transmitted obligate intracellular bacteria that invade white or red blood cells to cause debilitating and potentially fatal infections. A. phagocytophilum, a human and veterinary pathogen, infects neutrophils to cause granulocytic anaplasmosis. A. marginale invades bovine erythrocytes. Evidence suggests that both species may also infect endothelial cells in vivo. In mammalian and arthropod host cells, A. phagocytophilum and A. marginale reside in host cell derived pathogen-occupied vacuoles (POVs). While it was recently demonstrated that the A. phagocytophilum-occupied vacuole (ApV) intercepts membrane traffic from the trans-Golgi network, it is unclear if it or the A. marginale-occupied vacuole (AmV) interacts with other secretory organelles. Here, we demonstrate that the ApV and AmV extensively interact with the host endoplasmic reticulum (ER) in endothelial, myeloid, and/or tick cells. ER lumen markers, calreticulin, and protein disulfide isomerase, and the ER membrane marker, derlin-1, were pronouncedly recruited to the peripheries of both POVs. ApV association with the ER initiated early and continued throughout the infection cycle. Both the ApV and AmV interacted with the rough ER and smooth ER. However, only derlin-1-positive rough ER derived vesicles were delivered into the ApV lumen where they localized with intravacuolar bacteria. Transmission electron microscopy identified multiple ER-POV membrane contact sites on the cytosolic faces of both species' vacuoles that corresponded to areas on the vacuoles' lumenal faces where intravacuolar Anaplasma organisms closely associated. A. phagocytophilum is known to hijack Rab10, a GTPase that regulates ER dynamics and morphology. Yet, ApV-ER interactions were unhindered in cells in which Rab10 had been knocked down, demonstrating that the GTPase is dispensable for the bacterium to parasitize the ER. These data establish the ApV and AmV as pathogen-host interfaces that directly

  8. The Pathogen-Occupied Vacuoles of Anaplasma phagocytophilum and Anaplasma marginale Interact with the Endoplasmic Reticulum

    PubMed Central

    Truchan, Hilary K.; Cockburn, Chelsea L.; Hebert, Kathryn S.; Magunda, Forgivemore; Noh, Susan M.; Carlyon, Jason A.

    2016-01-01

    The genus Anaplasma consists of tick-transmitted obligate intracellular bacteria that invade white or red blood cells to cause debilitating and potentially fatal infections. A. phagocytophilum, a human and veterinary pathogen, infects neutrophils to cause granulocytic anaplasmosis. A. marginale invades bovine erythrocytes. Evidence suggests that both species may also infect endothelial cells in vivo. In mammalian and arthropod host cells, A. phagocytophilum and A. marginale reside in host cell derived pathogen-occupied vacuoles (POVs). While it was recently demonstrated that the A. phagocytophilum-occupied vacuole (ApV) intercepts membrane traffic from the trans-Golgi network, it is unclear if it or the A. marginale-occupied vacuole (AmV) interacts with other secretory organelles. Here, we demonstrate that the ApV and AmV extensively interact with the host endoplasmic reticulum (ER) in endothelial, myeloid, and/or tick cells. ER lumen markers, calreticulin, and protein disulfide isomerase, and the ER membrane marker, derlin-1, were pronouncedly recruited to the peripheries of both POVs. ApV association with the ER initiated early and continued throughout the infection cycle. Both the ApV and AmV interacted with the rough ER and smooth ER. However, only derlin-1-positive rough ER derived vesicles were delivered into the ApV lumen where they localized with intravacuolar bacteria. Transmission electron microscopy identified multiple ER-POV membrane contact sites on the cytosolic faces of both species' vacuoles that corresponded to areas on the vacuoles' lumenal faces where intravacuolar Anaplasma organisms closely associated. A. phagocytophilum is known to hijack Rab10, a GTPase that regulates ER dynamics and morphology. Yet, ApV-ER interactions were unhindered in cells in which Rab10 had been knocked down, demonstrating that the GTPase is dispensable for the bacterium to parasitize the ER. These data establish the ApV and AmV as pathogen-host interfaces that directly

  9. Interstitial Cells: Regulators of Smooth Muscle Function

    PubMed Central

    Sanders, Kenton M.; Ward, Sean M.; Koh, Sang Don

    2014-01-01

    Smooth muscles are complex tissues containing a variety of cells in addition to muscle cells. Interstitial cells of mesenchymal origin interact with and form electrical connectivity with smooth muscle cells in many organs, and these cells provide important regulatory functions. For example, in the gastrointestinal tract, interstitial cells of Cajal (ICC) and PDGFRα+ cells have been described, in detail, and represent distinct classes of cells with unique ultrastructure, molecular phenotypes, and functions. Smooth muscle cells are electrically coupled to ICC and PDGFRα+ cells, forming an integrated unit called the SIP syncytium. SIP cells express a variety of receptors and ion channels, and conductance changes in any type of SIP cell affect the excitability and responses of the syncytium. SIP cells are known to provide pacemaker activity, propagation pathways for slow waves, transduction of inputs from motor neurons, and mechanosensitivity. Loss of interstitial cells has been associated with motor disorders of the gut. Interstitial cells are also found in a variety of other smooth muscles; however, in most cases, the physiological and pathophysiological roles for these cells have not been clearly defined. This review describes structural, functional, and molecular features of interstitial cells and discusses their contributions in determining the behaviors of smooth muscle tissues. PMID:24987007

  10. Migration of Airway Smooth Muscle Cells

    PubMed Central

    Gerthoffer, William T.

    2008-01-01

    Migration of smooth muscle cells is a process fundamental to development of hollow organs, including blood vessels and the airways. Migration is also thought to be part of the response to tissue injury. It has also been suggested to contribute to airways remodeling triggered by chronic inflammation. In both nonmuscle and smooth muscle cells numerous external signaling molecules and internal signal transduction pathways contribute to cell migration. The review includes evidence for the functional significance of airway smooth muscle migration, a summary of promigratory and antimigratory agents, and summaries of important signaling pathways mediating migration. Important signaling pathways and effector proteins described include small G proteins, phosphatidylinositol 3-kinases (PI3-K), Rho activated protein kinase (ROCK), p21-activated protein kinases (PAK), Src family tyrosine kinases, and mitogen-activated protein kinases (MAPK). These signaling modules control multiple critical effector proteins including actin nucleating, capping and severing proteins, myosin motors, and proteins that remodel microtubules. Actin filament remodeling, focal contact remodeling and propulsive force of molecular motors are all coordinated to move cells along gradients of chemical cues, matrix adhesiveness, or matrix stiffness. Airway smooth muscle cell migration can be modulated in vitro by drugs commonly used in pulmonary medicine including β-adrenergic agonists and corticosteroids. Future studies of airway smooth muscle cell migration may uncover novel targets for drugs aimed at modifying airway remodeling. PMID:18094091

  11. Role of epidermal growth factor receptor and endoplasmic reticulum stress in vascular remodeling induced by angiotensin II.

    PubMed

    Takayanagi, Takehiko; Kawai, Tatsuo; Forrester, Steven J; Obama, Takashi; Tsuji, Toshiyuki; Fukuda, Yamato; Elliott, Katherine J; Tilley, Douglas G; Davisson, Robin L; Park, Joon-Young; Eguchi, Satoru

    2015-06-01

    The mechanisms by which angiotensin II (AngII) elevates blood pressure and enhances end-organ damage seem to be distinct. However, the signal transduction cascade by which AngII specifically mediates vascular remodeling such as medial hypertrophy and perivascular fibrosis remains incomplete. We have previously shown that AngII-induced epidermal growth factor receptor (EGFR) transactivation is mediated by disintegrin and metalloproteinase domain 17 (ADAM17), and that this signaling is required for vascular smooth muscle cell hypertrophy but not for contractile signaling in response to AngII. Recent studies have implicated endoplasmic reticulum (ER) stress in hypertension. Interestingly, EGFR is capable of inducing ER stress. The aim of this study was to test the hypothesis that activation of EGFR and ER stress are critical components required for vascular remodeling but not hypertension induced by AngII. Mice were infused with AngII for 2 weeks with or without treatment of EGFR inhibitor, erlotinib, or ER chaperone, 4-phenylbutyrate. AngII infusion induced vascular medial hypertrophy in the heart, kidney and aorta, and perivascular fibrosis in heart and kidney, cardiac hypertrophy, and hypertension. Treatment with erlotinib as well as 4-phenylbutyrate attenuated vascular remodeling and cardiac hypertrophy but not hypertension. In addition, AngII infusion enhanced ADAM17 expression, EGFR activation, and ER/oxidative stress in the vasculature, which were diminished in both erlotinib-treated and 4-phenylbutyrate-treated mice. ADAM17 induction and EGFR activation by AngII in vascular cells were also prevented by inhibition of EGFR or ER stress. In conclusion, AngII induces vascular remodeling by EGFR activation and ER stress via a signaling mechanism involving ADAM17 induction independent of hypertension.

  12. Valosin-containing protein-interacting membrane protein (VIMP) links the endoplasmic reticulum with microtubules in concert with cytoskeleton-linking membrane protein (CLIMP)-63.

    PubMed

    Noda, Chikano; Kimura, Hana; Arasaki, Kohei; Matsushita, Mitsuru; Yamamoto, Akitsugu; Wakana, Yuichi; Inoue, Hiroki; Tagaya, Mitsuo

    2014-08-29

    The distribution and morphology of the endoplasmic reticulum (ER) in mammalian cells depend on both dynamic and static interactions of ER membrane proteins with microtubules (MTs). Cytoskeleton-linking membrane protein (CLIMP)-63 is exclusively localized in sheet-like ER membranes, typical structures of the rough ER, and plays a pivotal role in the static interaction with MTs. Our previous study showed that the 42-kDa ER-residing form of syntaxin 5 (Syn5L) regulates ER structure through the interactions with both CLIMP-63 and MTs. Here, we extend our previous study and show that the valosin-containing protein/p97-interacting membrane protein (VIMP)/SelS is also a member of the family of proteins that shape the ER by interacting with MTs. Depletion of VIMP causes the spreading of the ER to the cell periphery and affects an MT-dependent process on the ER. Although VIMP can interact with CLIMP-63 and Syn5L, it does not interact with MT-binding ER proteins (such as Reep1) that shape the tubular smooth ER, suggesting that different sets of MT-binding ER proteins are used to organize different ER subdomains.

  13. Intrinsic membrane glycoproteins with cytosol-oriented sugars in the endoplasmic reticulum

    SciTech Connect

    Abeijon, C.; Hirschberg, C.B.

    1988-02-01

    The authors have examined the topography of N-acetylglucosamine-terminating glycoproteins in membranes from rat liver smooth and rough endoplasmic reticulum (SER and RER). It was found that some of these glycoproteins are intrinsic membrane proteins with their sugars facing the cytosolic rather than the luminal side. This conclusion was reached by using vesicles from the SER and RER that were sealed and of the same topographical orientation as in vivo. These vesicles were incubated with UDP-(/sup 14/C)galactose (which does not enter the vesicles) and saturating amounts of soluble galactosyltransferase from milk, an enzyme that does not penetrate the lumen of the vesicles and that specifically adds galactose to terminal N-acetylglucosamine in a ..beta..1-4 linkage. Radioactive galactose was mainly transferred to SER proteins of apparent molecular mass 56 and 110 kDa and to a lesser extent RER and SER proteins of apparent molecular mass 46 and 72 kDa. These proteins are intrinsic membrane proteins, based on the inability of sodium carbonate at pH 11.5 to remove them from the membranes. Studies with peptide N-glycosidase F and chemical ..beta..-elimination showed that the 56-kDa protein of the SER vesicles contained terminal N-acetylglucosamine in an O-linkage to the protein. The above results suggest that some sugars of glycoproteins in the endoplasmic reticulum may attain their final orientation in the membrane by mechanisms yet to be determined.

  14. Taking organelles apart, putting them back together and creating new ones: lessons from the endoplasmic reticulum.

    PubMed

    Lavoie, Christine; Roy, Line; Lanoix, Joël; Taheri, Mariam; Young, Robin; Thibault, Geneviève; Farah, Carol Abi; Leclerc, Nicole; Paiement, Jacques

    2011-06-01

    The endoplasmic reticulum (ER) is a highly dynamic organelle. It is composed of four subcompartments including nuclear envelope (NE), rough ER (rER), smooth ER (sER) and transitional ER (tER). The subcompartments are interconnected, can fragment and dissociate and are able to reassemble again. They coordinate with cell function by way of protein regulators in the surrounding cytosol. The activity of the many associated molecular machines of the ER as well as the fluid nature of the limiting membrane of the ER contribute extensively to the dynamics of the ER. This review examines the properties of the ER that permit its isolation and purification and the physiological conditions that permit reconstitution both in vitro and in vivo in normal and in disease conditions.

  15. Hydrogen Sulfide Improves Vascular Calcification in Rats by Inhibiting Endoplasmic Reticulum Stress

    PubMed Central

    Yang, Rui; Teng, Xu; Li, Hui; Xue, Hong-Mei; Guo, Qi; Xiao, Lin; Wu, Yu-Ming

    2016-01-01

    In this study, the vitamin D3 plus nicotine (VDN) model of rats was used to prove that H2S alleviates vascular calcification (VC) and phenotype transformation of vascular smooth muscle cells (VSMC). Besides, H2S can also inhibit endoplasmic reticulum stress (ERS) of calcified aortic tissues. The effect of H2S on alleviating VC and phenotype transformation of VSMC can be blocked by TM, while PBA also alleviated VC and phenotype transformation of VSMC that was similar to the effect of H2S. These results suggest that H2S may alleviate rat aorta VC by inhibiting ERS, providing new target and perspective for prevention and treatment of VC. PMID:27022436

  16. Activation of autophagy by unfolded proteins during endoplasmic reticulum stress.

    PubMed

    Yang, Xiaochen; Srivastava, Renu; Howell, Stephen H; Bassham, Diane C

    2016-01-01

    Endoplasmic reticulum stress is defined as the accumulation of unfolded proteins in the endoplasmic reticulum, and is caused by conditions such as heat or agents that cause endoplasmic reticulum stress, including tunicamycin and dithiothreitol. Autophagy, a major pathway for degradation of macromolecules in the vacuole, is activated by these stress agents in a manner dependent on inositol-requiring enzyme 1b (IRE1b), and delivers endoplasmic reticulum fragments to the vacuole for degradation. In this study, we examined the mechanism for activation of autophagy during endoplasmic reticulum stress in Arabidopsis thaliana. The chemical chaperones sodium 4-phenylbutyrate and tauroursodeoxycholic acid were found to reduce tunicamycin- or dithiothreitol-induced autophagy, but not autophagy caused by unrelated stresses. Similarly, over-expression of BINDING IMMUNOGLOBULIN PROTEIN (BIP), encoding a heat shock protein 70 (HSP70) molecular chaperone, reduced autophagy. Autophagy activated by heat stress was also found to be partially dependent on IRE1b and to be inhibited by sodium 4-phenylbutyrate, suggesting that heat-induced autophagy is due to accumulation of unfolded proteins in the endoplasmic reticulum. Expression in Arabidopsis of the misfolded protein mimics zeolin or a mutated form of carboxypeptidase Y (CPY*) also induced autophagy in an IRE1b-dependent manner. Moreover, zeolin and CPY* partially co-localized with the autophagic body marker GFP-ATG8e, indicating delivery to the vacuole by autophagy. We conclude that accumulation of unfolded proteins in the endoplasmic reticulum is a trigger for autophagy under conditions that cause endoplasmic reticulum stress. PMID:26616142

  17. Endoplasmic reticulum stress in adipose tissue augments lipolysis.

    PubMed

    Bogdanovic, Elena; Kraus, Nicole; Patsouris, David; Diao, Li; Wang, Vivian; Abdullahi, Abdikarim; Jeschke, Marc G

    2015-01-01

    The endoplasmic reticulum (ER) is an organelle important for protein synthesis and folding, lipid synthesis and Ca(2+) homoeostasis. Consequently, ER stress or dysfunction affects numerous cellular processes and has been implicated as a contributing factor in several pathophysiological conditions. Tunicamycin induces ER stress in various cell types in vitro as well as in vivo. In mice, a hallmark of tunicamycin administration is the development of fatty livers within 24-48 hrs accompanied by hepatic ER stress. We hypothesized that tunicamycin would induce ER stress in adipose tissue that would lead to increased lipolysis and subsequently to fatty infiltration of the liver and hepatomegaly. Our results show that intraperitoneal administration of tunicamycin rapidly induced an ER stress response in adipose tissue that correlated with increased circulating free fatty acids (FFAs) and glycerol along with decreased adipose tissue mass and lipid droplet size. Furthermore, we found that in addition to fatty infiltration of the liver as well as hepatomegaly, lipid accumulation was also present in the heart, skeletal muscle and kidney. To corroborate our findings to a clinical setting, we examined adipose tissue from burned patients where increases in lipolysis and the development of fatty livers have been well documented. We found that burned patients displayed significant ER stress within adipose tissue and that ER stress augments lipolysis in cultured human adipocytes. Our results indicate a possible role for ER stress induced lipolysis in adipose tissue as an underlying mechanism contributing to increases in circulating FFAs and fatty infiltration into other organs.

  18. Chlamydiae interaction with the endoplasmic reticulum: contact, function and consequences.

    PubMed

    Derré, Isabelle

    2015-07-01

    Chlamydiae and chlamydiae-related organisms are obligate intracellular bacterial pathogens. They reside in a membrane-bound compartment termed the inclusion and have evolved sophisticated mechanisms to interact with cellular organelles. This review focuses on the nature, the function(s) and the consequences of chlamydiae-inclusion interaction with the endoplasmic reticulum (ER). The inclusion membrane establishes very close contact with the ER at specific sites termed ER-inclusion membrane contact sites (MCSs). These MCSs are constituted of a specific set of factors, including the C. trachomatis effector protein IncD and the host cell proteins CERT and VAPA/B. Because CERT and VAPA/B have a demonstrated role in the non-vesicular trafficking of lipids between the ER and the Golgi, it was proposed that Chlamydia establish MCSs with the ER to acquire host lipids. However, the recruitment of additional factors to ER-inclusion MCSs, such as the ER calcium sensor STIM1, may suggest additional functions unrelated to lipid acquisition. Finally, chlamydiae interaction with the ER appears to induce the ER stress response, but this response is quickly dampened by chlamydiae to promote host cell survival. PMID:25930206

  19. Terasaki Ramps in the Endoplasmic Reticulum: Structure, Function and Formation

    NASA Astrophysics Data System (ADS)

    Huber, Greg; Guven, Jemal; Valencia, Dulce-Maria

    2015-03-01

    The endoplasmic reticulum (ER) has long been considered an exceedingly important and complex cellular organelle in eukaryotes (like you). It is a membrane structure, part folded lamellae, part tubular network, that both envelopes the nucleus and threads its way outward, all the way to the cell's periphery. Despite the elegant mechanics of bilayer membranes offered by the work of Helfrich and Canham, as far as the ER is concerned, theory has mostly sat on the sidelines. However, refined imaging of the ER has recently revealed beautiful and subtle geometrical forms - simple geometries, from the mathematical point of view - which some have called a ``parking garage for ribosomes.'' I'll review the discovery and physics of Terasaki ramps and discuss their relation to cell-biological questions, such as ER and nuclear-membrane re-organization during mitosis. Rather than being a footnote in a textbook on differential geometry, these structures suggest answers to a number of the ER's structure-function problems.

  20. The Role of the Endoplasmic Reticulum in Peroxisome Biogenesis

    PubMed Central

    Dimitrov, Lazar; Lam, Sheung Kwan; Schekman, Randy

    2013-01-01

    Peroxisomes are essential cellular organelles involved in lipid metabolism. Patients affected by severe peroxisome biogenesis disorders rarely survive their first year. Genetic screens in several model organisms have identified more than 30 PEX genes that are required for the formation of functional peroxisomes. Despite significant work on the PEX genes, the biogenic origin of peroxisomes remains controversial. For at least two decades, the prevailing model postulated that peroxisomes propagate by growth and fission of preexisting peroxisomes. In this review, we focus on the recent evidence supporting a new, semiautonomous model of peroxisomal biogenesis. According to this model, peroxisomal membrane proteins (PMPs) traffic from the endoplasmic reticulum (ER) to the peroxisome by a vesicular budding, targeting, and fusion process while peroxisomal matrix proteins are imported into the organelle by an autonomous, posttranslational mechanism. We highlight the contradictory conclusions reached to answer the question of how PMPs are inserted into the ER. We then review what we know and what still remains to be elucidated about the mechanism of PMP exit from the ER and the contribution of preperoxisomal vesicles to mature peroxisomes. Finally, we discuss discrepancies in our understanding of de novo peroxisome biogenesis in wild-type cells. We anticipate that resolving these key issues will lead to a more complete picture of peroxisome biogenesis. PMID:23637287

  1. Probing Endoplasmic Reticulum Dynamics using Fluorescence Imaging and Photobleaching Techniques

    PubMed Central

    Costantini, Lindsey; Snapp, Erik

    2013-01-01

    This UNIT describes approaches and tools for studying the dynamics and organization of endoplasmic reticulum (ER) membranes and proteins in living cells using commercially available widefield and confocal laser scanning microscopes (CLSM). It has been long appreciated that the ER plays a number of key roles in secretory protein biogenesis, calcium regulation, and lipid synthesis. However, study of these processes has been often restricted to biochemical assays that average the behaviors of millions of lysed cells or to imaging static fixed cells. Now, with new fluorescent protein reporter tools, highly sensitive commercial microscopes, and photobleaching techniques, it is possible to interrogate the behaviors of ER proteins, membranes, and stress pathways in single cells with exquisite spatial and temporal resolution. The ER presents a unique set of imaging challenges including the high mobility of ER membranes, a diverse range of dynamic ER structures, and the influence of post-translational modifications on fluorescent protein reporters. Solutions to these challenges are described and considerations for performing photobleaching assays, especially Fluorescence Recovery after Photobleaching (FRAP) and Fluorescence Loss in Photobleaching (FLIP) for ER proteins will be discussed. In addition, ER reporters and ER-specific pharmacologic compounds are presented with a focus on misfolded secretory protein stress and the Unfolded Protein Response (UPR). PMID:24510787

  2. Endoplasmic Reticulum Stress in Endometrial Cancer

    PubMed Central

    Ulianich, Luca; Insabato, Luigi

    2014-01-01

    Endometrial cancer (EC) is a common gynecologic malignancy often diagnosed at early stage. In spite of a huge advance in our understanding of EC biology, therapeutic modalities do not have significantly changed over the past 40 years. A restricted number of genes have been reported to be mutated in EC, mediating cell proliferation and invasiveness. However, besides these alterations, few other groups and ourselves recently identified the activation of the unfolded protein response (UPR) and GRP78 increase following endoplasmic reticulum (ER) stress as mechanisms favoring growth and invasion of EC cells. Here, a concise update on currently available data in the field is presented, analyzing the crosstalk between the UPR and the main signaling pathways regulating EC cell proliferation and survival. It is evident that this is a rapidly expanding and promising issue. However, more data are very likely to yield a better understanding on the mechanisms through which EC cells can survive the low oxygen and glucose tumor microenvironment. In this perspective, the UPR and, particularly, GRP78 might constitute a novel target for the treatment of EC in combination with traditional adjuvant therapy. PMID:25593927

  3. Endoplasmic reticulum stress in periimplantation embryos.

    PubMed

    Michalak, Marek; Gye, Myung Chan

    2015-03-01

    Stress coping mechanisms are critical to minimize or overcome damage caused by ever changing environmental conditions. They are designed to promote cell survival. The unfolded protein response (UPR) pathway is mobilized in response to the accumulation of unfolded proteins, ultimately in order to regain endoplasmic reticulum (ER) homeostasis. Various elements of coping responses to ER stress including Perk, Ask1, Bip, Chop, Gadd34, Ire1, Atf4, Atf6, and Xbp1 have been identified and were found to be inducible in oocytes and preimplantation embryos, suggesting that, as a normal part of the cellular adaptive mechanism, these coping responses, including the UPR, play a pivotal role in the development of preimplantation embryos. As such, the UPR-associated molecules and pathways may become useful markers for the potential diagnosis of stress conditions for preimplantation embryos. After implantation, ER stress-induced coping responses become physiologically important for a normal decidual response, placentation, and early organogenesis. Attenuation of ER stress coping responses by tauroursodeoxycholate and salubrinal was effective for prevention of cell death of cultured embryos. Further elucidation of new and relevant ER stress coping responses in periimplantation embryos might contribute to a comprehensive understanding of the regulation of normal development of embryonic development and potentiation of embryonic development in vitro. PMID:25874167

  4. Shaping the endoplasmic reticulum in vitro.

    PubMed

    Ferencz, Csilla-Maria; Guigas, Gernot; Veres, Andreas; Neumann, Brigitte; Stemmann, Olaf; Weiss, Matthias

    2016-09-01

    Organelles in eukaryotic cells often have complex shapes that deviate significantly from simple spheres. A prime example is the endoplasmic reticulum (ER) that forms an extensive network of membrane tubules in many mammalian cell types and in reconstitution assays in vitro. Despite the successful hunt for molecular determinants of ER shape we are still far from having a comprehensive understanding of ER network morphogenesis. Here, we have studied the hitherto neglected influence of the host substrate when reconstituting ER networks in vitro as compared to ER networks in vivo. In culture cells we observed cytoplasm-spanning ER networks with tubules being connected almost exclusively by three-way junctions and segment lengths being narrowly distributed around a mean length of about 1μm. In contrast, networks reconstituted from purified ER microsomes on flat glass or gel substrates of varying stiffness showed significantly broader length distributions with an up to fourfold larger mean length. Self-assembly of ER microsomes on small oil droplets, however, yielded networks that resembled more closely the native ER network of mammalian cells. We conclude from these observations that the ER microsomes' inherent self-assembly capacity is sufficient to support network formation with a native geometry if the influence of the host substrate's surface chemistry becomes negligible. We hypothesize that under these conditions the networks' preference for three-way junctions follows from creating 'starfish-shaped' vesicles when ER microsomes with a protein-induced spontaneous curvature undergo fusion. PMID:27287725

  5. Endoplasmic Reticulum Stress, Genome Damage, and Cancer

    PubMed Central

    Dicks, Naomi; Gutierrez, Karina; Michalak, Marek; Bordignon, Vilceu; Agellon, Luis B.

    2015-01-01

    Endoplasmic reticulum (ER) stress has been linked to many diseases, including cancer. A large body of work has focused on the activation of the ER stress response in cancer cells to facilitate their survival and tumor growth; however, there are some studies suggesting that the ER stress response can also mitigate cancer progression. Despite these contradictions, it is clear that the ER stress response is closely associated with cancer biology. The ER stress response classically encompasses activation of three separate pathways, which are collectively categorized the unfolded protein response (UPR). The UPR has been extensively studied in various cancers and appears to confer a selective advantage to tumor cells to facilitate their enhanced growth and resistance to anti-cancer agents. It has also been shown that ER stress induces chromatin changes, which can also facilitate cell survival. Chromatin remodeling has been linked with many cancers through repression of tumor suppressor and apoptosis genes. Interplay between the classic UPR and genome damage repair mechanisms may have important implications in the transformation process of normal cells into cancer cells. PMID:25692096

  6. Smooth eigenvalue correction

    NASA Astrophysics Data System (ADS)

    Hendrikse, Anne; Veldhuis, Raymond; Spreeuwers, Luuk

    2013-12-01

    Second-order statistics play an important role in data modeling. Nowadays, there is a tendency toward measuring more signals with higher resolution (e.g., high-resolution video), causing a rapid increase of dimensionality of the measured samples, while the number of samples remains more or less the same. As a result the eigenvalue estimates are significantly biased as described by the Marčenko Pastur equation for the limit of both the number of samples and their dimensionality going to infinity. By introducing a smoothness factor, we show that the Marčenko Pastur equation can be used in practical situations where both the number of samples and their dimensionality remain finite. Based on this result we derive methods, one already known and one new to our knowledge, to estimate the sample eigenvalues when the population eigenvalues are known. However, usually the sample eigenvalues are known and the population eigenvalues are required. We therefore applied one of the these methods in a feedback loop, resulting in an eigenvalue bias correction method. We compare this eigenvalue correction method with the state-of-the-art methods and show that our method outperforms other methods particularly in real-life situations often encountered in biometrics: underdetermined configurations, high-dimensional configurations, and configurations where the eigenvalues are exponentially distributed.

  7. New smooth hybrid inflation

    SciTech Connect

    Lazarides, George; Vamvasakis, Achilleas

    2007-10-15

    We consider the extension of the supersymmetric Pati-Salam model which solves the b-quark mass problem of supersymmetric grand unified models with exact Yukawa unification and universal boundary conditions and leads to the so-called new shifted hybrid inflationary scenario. We show that this model can also lead to a new version of smooth hybrid inflation based only on renormalizable interactions provided that a particular parameter of its superpotential is somewhat small. The potential possesses valleys of minima with classical inclination, which can be used as inflationary paths. The model is consistent with the fitting of the three-year Wilkinson microwave anisotropy probe data by the standard power-law cosmological model with cold dark matter and a cosmological constant. In particular, the spectral index turns out to be adequately small so that it is compatible with the data. Moreover, the Pati-Salam gauge group is broken to the standard model gauge group during inflation and, thus, no monopoles are formed at the end of inflation. Supergravity corrections based on a nonminimal Kaehler potential with a convenient choice of a sign keep the spectral index comfortably within the allowed range without generating maxima and minima of the potential on the inflationary path. So, unnatural restrictions on the initial conditions for inflation can be avoided.

  8. Ceramic coatings on smooth surfaces

    NASA Technical Reports Server (NTRS)

    Miller, R. A. (Inventor); Brindley, W. J. (Inventor); Rouge, C. J. (Inventor)

    1991-01-01

    A metallic coating is plasma sprayed onto a smooth surface of a metal alloy substitute or on a bond coating. An initial thin ceramic layer is low pressure sprayed onto the smooth surface of the substrate or bond coating. Another ceramic layer is atmospheric plasma sprayed onto the initial ceramic layer.

  9. Conservative smoothing versus artificial viscosity

    SciTech Connect

    Guenther, C.; Hicks, D.L.; Swegle, J.W.

    1994-08-01

    This report was stimulated by some recent investigations of S.P.H. (Smoothed Particle Hydrodynamics method). Solid dynamics computations with S.P.H. show symptoms of instabilities which are not eliminated by artificial viscosities. Both analysis and experiment indicate that conservative smoothing eliminates the instabilities in S.P.H. computations which artificial viscosities cannot. Questions were raised as to whether conservative smoothing might smear solutions more than artificial viscosity. Conservative smoothing, properly used, can produce more accurate solutions than the von Neumann-Richtmyer-Landshoff artificial viscosity which has been the standard for many years. The authors illustrate this using the vNR scheme on a test problem with known exact solution involving a shock collision in an ideal gas. They show that the norms of the errors with conservative smoothing are significantly smaller than the norms of the errors with artificial viscosity.

  10. Calcium Sensitization Mechanisms in Gastrointestinal Smooth Muscles

    PubMed Central

    Perrino, Brian A

    2016-01-01

    An increase in intracellular Ca2+ is the primary trigger of contraction of gastrointestinal (GI) smooth muscles. However, increasing the Ca2+ sensitivity of the myofilaments by elevating myosin light chain phosphorylation also plays an essential role. Inhibiting myosin light chain phosphatase activity with protein kinase C-potentiated phosphatase inhibitor protein-17 kDa (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) phosphorylation is considered to be the primary mechanism underlying myofilament Ca2+ sensitization. The relative importance of Ca2+ sensitization mechanisms to the diverse patterns of GI motility is likely related to the varied functional roles of GI smooth muscles. Increases in CPI-17 and MYPT1 phosphorylation in response to agonist stimulation regulate myosin light chain phosphatase activity in phasic, tonic, and sphincteric GI smooth muscles. Recent evidence suggests that MYPT1 phosphorylation may also contribute to force generation by reorganization of the actin cytoskeleton. The mechanisms responsible for maintaining constitutive CPI-17 and MYPT1 phosphorylation in GI smooth muscles are still largely unknown. The characteristics of the cell-types comprising the neuroeffector junction lead to fundamental differences between the effects of exogenous agonists and endogenous neurotransmitters on Ca2+ sensitization mechanisms. The contribution of various cell-types within the tunica muscularis to the motor responses of GI organs to neurotransmission must be considered when determining the mechanisms by which Ca2+ sensitization pathways are activated. The signaling pathways regulating Ca2+ sensitization may provide novel therapeutic strategies for controlling GI motility. This article will provide an overview of the current understanding of the biochemical basis for the regulation of Ca2+ sensitization, while also discussing the functional importance to different smooth muscles of the GI tract. PMID:26701920

  11. Regeneration and Maintenance of Intestinal Smooth Muscle Phenotypes

    NASA Astrophysics Data System (ADS)

    Walthers, Christopher M.

    Tissue engineering is an emerging field of biomedical engineering that involves growing artificial organs to replace those lost to disease or injury. Within tissue engineering, there is a demand for artificial smooth muscle to repair tissues of the digestive tract, bladder, and vascular systems. Attempts to develop engineered smooth muscle tissues capable of contracting with sufficient strength to be clinically relevant have so far proven unsatisfactory. The goal of this research was to develop and sustain mature, contractile smooth muscle. Survival of implanted SMCs is critical to sustain the benefits of engineered smooth muscle. Survival of implanted smooth muscle cells was studied with layered, electrospun polycaprolactone implants with lasercut holes ranging from 0--25% porosity. It was found that greater angiogenesis was associated with increased survival of implanted cells, with a large increase at a threshold between 20% and 25% porosity. Heparan sulfate coatings improved the speed of blood vessel infiltration after 14 days of implantation. With these considerations, thicker engineered tissues may be possible. An improved smooth muscle tissue culture technique was utilized. Contracting smooth muscle was produced in culture by maintaining the native smooth muscle tissue organization, specifically by sustaining intact smooth muscle strips rather than dissociating tissue in to isolated smooth muscle cells. Isolated cells showed a decrease in maturity and contained fewer enteric neural and glial cells. Muscle strips also exhibited periodic contraction and regular fluctuation of intracellular calclium. The muscle strip maturity persisted after implantation in omentum for 14 days on polycaprolactone scaffolds. A low-cost, disposable bioreactor was developed to further improve maturity of cultured smooth muscle cells in an environment of controlled cyclical stress.The bioreactor consistently applied repeated mechanical strain with controllable inputs for strain

  12. Nodal endoplasmic reticulum, a specialized form of endoplasmic reticulum found in gravity-sensing root tip columella cells

    NASA Technical Reports Server (NTRS)

    Zheng, H. Q.; Staehelin, L. A.

    2001-01-01

    The endoplasmic reticulum (ER) of columella root cap cells has been postulated to play a role in gravity sensing. We have re-examined the ultrastructure of columella cells in tobacco (Nicotiana tabacum) root tips preserved by high-pressure freezing/freeze-substitution techniques to gain more precise information about the organization of the ER in such cells. The most notable findings are: the identification of a specialized form of ER, termed "nodal ER," which is found exclusively in columella cells; the demonstration that the bulk of the ER is organized in the form of a tubular network that is confined to a peripheral layer under the plasma membrane; and the discovery that this ER-rich peripheral region excludes Golgi stacks, vacuoles, and amyloplasts but not mitochondria. Nodal ER domains consist of an approximately 100-nm-diameter central rod composed of oblong subunits to which usually seven sheets of rough ER are attached along their margins. These domains form patches at the interface between the peripheral ER network and the ER-free central region of the cells, and they occupy defined positions within central and flanking columella cells. Over one-half of the nodal ER domains are located along the outer tangential walls of the flanking cells. Cytochalasin D and latrunculin A cause an increase in size and a decrease in numbers of nodal ER domains. We postulate that the nodal ER membranes locally modulate the gravisensing signals produced by the sedimenting amyloplasts, and that the confinement of all ER membranes to the cell periphery serves to enhance the sedimentability of the amyloplasts in the central region of columella cells.

  13. Titanium Dioxide Nanoparticles Induce Endoplasmic Reticulum Stress-Mediated Autophagic Cell Death via Mitochondria-Associated Endoplasmic Reticulum Membrane Disruption in Normal Lung Cells.

    PubMed

    Yu, Kyeong-Nam; Chang, Seung-Hee; Park, Soo Jin; Lim, Joohyun; Lee, Jinkyu; Yoon, Tae-Jong; Kim, Jun-Sung; Cho, Myung-Haing

    2015-01-01

    Nanomaterials are used in diverse fields including food, cosmetic, and medical industries. Titanium dioxide nanoparticles (TiO2-NP) are widely used, but their effects on biological systems and mechanism of toxicity have not been elucidated fully. Here, we report the toxicological mechanism of TiO2-NP in cell organelles. Human bronchial epithelial cells (16HBE14o-) were exposed to 50 and 100 μg/mL TiO2-NP for 24 and 48 h. Our results showed that TiO2-NP induced endoplasmic reticulum (ER) stress in the cells and disrupted the mitochondria-associated endoplasmic reticulum membranes (MAMs) and calcium ion balance, thereby increasing autophagy. In contrast, an inhibitor of ER stress, tauroursodeoxycholic acid (TUDCA), mitigated the cellular toxic response, suggesting that TiO2-NP promoted toxicity via ER stress. This novel mechanism of TiO2-NP toxicity in human bronchial epithelial cells suggests that further exhaustive research on the harmful effects of these nanoparticles in relevant organisms is needed for their safe application. PMID:26121477

  14. Endoplasmic reticulum stress in liver disease.

    PubMed

    Malhi, Harmeet; Kaufman, Randal J

    2011-04-01

    The unfolded protein response (UPR) is activated upon the accumulation of misfolded proteins in the endoplasmic reticulum (ER) that are sensed by the binding immunoglobulin protein (BiP)/glucose-regulated protein 78 (GRP78). The accumulation of unfolded proteins sequesters BiP so it dissociates from three ER-transmembrane transducers leading to their activation. These transducers are inositol requiring (IRE) 1α, PKR-like ER kinase (PERK), and activating transcription factor (ATF) 6α. PERK phosphorylates eukaryotic initiation factor 2 alpha (eIF2α) resulting in global mRNA translation attenuation, and concurrently selectively increases the translation of several mRNAs, including the transcription factor ATF4, and its downstream target CHOP. IRE1α has kinase and endoribonuclease (RNase) activities. IRE1α autophosphorylation activates the RNase activity to splice XBP1 mRNA, to produce the active transcription factor sXBP1. IRE1α activation also recruits and activates the stress kinase JNK. ATF6α transits to the Golgi compartment where it is cleaved by intramembrane proteolysis to generate a soluble active transcription factor. These UPR pathways act in concert to increase ER content, expand the ER protein folding capacity, degrade misfolded proteins, and reduce the load of new proteins entering the ER. All of these are geared toward adaptation to resolve the protein folding defect. Faced with persistent ER stress, adaptation starts to fail and apoptosis occurs, possibly mediated through calcium perturbations, reactive oxygen species, and the proapoptotic transcription factor CHOP. The UPR is activated in several liver diseases; including obesity associated fatty liver disease, viral hepatitis, and alcohol-induced liver injury, all of which are associated with steatosis, raising the possibility that ER stress-dependent alteration in lipid homeostasis is the mechanism that underlies the steatosis. Hepatocyte apoptosis is a pathogenic event in several liver

  15. Endoplasmic motility spectral characteristics in plasmodium of Physarum polycephalum

    NASA Astrophysics Data System (ADS)

    Avsievich, T. I.; Ghaleb, K. E. S.; Frolov, S. V.; Proskurin, S. G.

    2015-03-01

    Spectral Fourier analysis of experimentally acquired velocity time dependencies, V(t), of shuttle endoplasmic motility in an isolated strand of plasmodium of slime mold Physarum Polycephalum has been realized. V(t) registration was performed in normal conditions and after the treatment by respiration inhibitors, which lead to a complete cessation of endoplasmic motion in the strand. Spectral analysis of the velocity time dependences of the endoplasm allows obtaining two distinct harmonic components in the spectra. Their ratio appeared to be constant in all cases, ν2/ν1=1.97±0.17. After the inhibitors are washed out respiratory system becomes normal, gradually restoring the activity of both harmonic oscillatory sources with time. Simulated velocity time dependences correspond to experimental data with good accuracy.

  16. Endoplasmic Reticulum-Associated Degradation and Lipid Homeostasis.

    PubMed

    Stevenson, Julian; Huang, Edmond Y; Olzmann, James A

    2016-07-17

    The endoplasmic reticulum is the port of entry for proteins into the secretory pathway and the site of synthesis for several important lipids, including cholesterol, triacylglycerol, and phospholipids. Protein production within the endoplasmic reticulum is tightly regulated by a cohort of resident machinery that coordinates the folding, modification, and deployment of secreted and integral membrane proteins. Proteins failing to attain their native conformation are degraded through the endoplasmic reticulum-associated degradation (ERAD) pathway via a series of tightly coupled steps: substrate recognition, dislocation, and ubiquitin-dependent proteasomal destruction. The same ERAD machinery also controls the flux through various metabolic pathways by coupling the turnover of metabolic enzymes to the levels of key metabolites. We review the current understanding and biological significance of ERAD-mediated regulation of lipid metabolism in mammalian cells. PMID:27296502

  17. Mitofusin 2 ablation increases endoplasmic reticulum-mitochondria coupling.

    PubMed

    Filadi, Riccardo; Greotti, Elisa; Turacchio, Gabriele; Luini, Alberto; Pozzan, Tullio; Pizzo, Paola

    2015-04-28

    The organization and mutual interactions between endoplasmic reticulum (ER) and mitochondria modulate key aspects of cell pathophysiology. Several proteins have been suggested to be involved in keeping ER and mitochondria at a correct distance. Among them, in mammalian cells, mitofusin 2 (Mfn2), located on both the outer mitochondrial membrane and the ER surface, has been proposed to be a physical tether between the two organelles, forming homotypic interactions and heterocomplexes with its homolog Mfn1. Recently, this widely accepted model has been challenged using quantitative EM analysis. Using a multiplicity of morphological, biochemical, functional, and genetic approaches, we demonstrate that Mfn2 ablation increases the structural and functional ER-mitochondria coupling. In particular, we show that in different cell types Mfn2 ablation or silencing increases the close contacts between the two organelles and strengthens the efficacy of inositol trisphosphate (IP3)-induced Ca(2+) transfer from the ER to mitochondria, sensitizing cells to a mitochondrial Ca(2+) overload-dependent death. We also show that the previously reported discrepancy between electron and fluorescence microscopy data on ER-mitochondria proximity in Mfn2-ablated cells is only apparent. By using a different type of morphological analysis of fluorescent images that takes into account (and corrects for) the gross modifications in mitochondrial shape resulting from Mfn2 ablation, we demonstrate that an increased proximity between the organelles is also observed by confocal microscopy when Mfn2 levels are reduced. Based on these results, we propose a new model for ER-mitochondria juxtaposition in which Mfn2 works as a tethering antagonist preventing an excessive, potentially toxic, proximity between the two organelles.

  18. Smooth Sailing with Contract Services.

    ERIC Educational Resources Information Center

    Fickes, Michael

    2001-01-01

    Discusses how to make the contract services relationship work smoothly for educational facilities. Covers topics of food, child care, and transportation services, along with a brief explanation of the benefits of outsourcing on-campus amenities. (GR)

  19. Active controls for ride smoothing

    NASA Technical Reports Server (NTRS)

    Conner, D. W.; Thompson, G. O.

    1976-01-01

    Active controls technology offers great promise for significantly smoothing the ride, and thus improving public and air carrier acceptance, of certain types of transport aircraft. Recent findings which support this promise are presented in the following three pertinent areas: (1) Ride quality versus degree of traveler satisfaction; (2) significant findings from a feasibility study of a ride smoothing system; and (3) potential ride problems identified for several advanced transport concepts.

  20. Radar data smoothing filter study

    NASA Technical Reports Server (NTRS)

    White, J. V.

    1984-01-01

    The accuracy of the current Wallops Flight Facility (WFF) data smoothing techniques for a variety of radars and payloads is examined. Alternative data reduction techniques are given and recommendations are made for improving radar data processing at WFF. A data adaptive algorithm, based on Kalman filtering and smoothing techniques, is also developed for estimating payload trajectories above the atmosphere from noisy time varying radar data. This algorithm is tested and verified using radar tracking data from WFF.

  1. The protein translocation machinery of the endoplasmic reticulum.

    PubMed

    Walter, P; Gilmore, R; Müller, M; Blobel, G

    1982-12-24

    The rough endoplasmic reticulum (r.e.r.) has been postulated to possess a single translation-coupled translocation system (in multiple copies) that effects signal sequence-mediated translocation of all secretory and lysosomal proteins and integration of all integral membrane proteins whose port of entry is the rough endoplasmic reticulum (G. Blobel 1980 Proc. natn. Acad. Sci. U.S.A. 77, 1496-1500). Two proteins have been isolated that are components of the r.e.r. translocation system. Their properties and function in protein translocation across and integration into membranes are discussed. PMID:6131460

  2. Smooth electrode and method of fabricating same

    DOEpatents

    Weaver, Stanton Earl; Kennerly, Stacey Joy; Aimi, Marco Francesco

    2012-08-14

    A smooth electrode is provided. The smooth electrode includes at least one metal layer having thickness greater than about 1 micron; wherein an average surface roughness of the smooth electrode is less than about 10 nm.

  3. Exotic smoothness and quantum gravity

    NASA Astrophysics Data System (ADS)

    Asselmeyer-Maluga, T.

    2010-08-01

    Since the first work on exotic smoothness in physics, it was folklore to assume a direct influence of exotic smoothness to quantum gravity. Thus, the negative result of Duston (2009 arXiv:0911.4068) was a surprise. A closer look into the semi-classical approach uncovered the implicit assumption of a close connection between geometry and smoothness structure. But both structures, geometry and smoothness, are independent of each other. In this paper we calculate the 'smoothness structure' part of the path integral in quantum gravity assuming that the 'sum over geometries' is already given. For that purpose we use the knot surgery of Fintushel and Stern applied to the class E(n) of elliptic surfaces. We mainly focus our attention to the K3 surfaces E(2). Then we assume that every exotic smoothness structure of the K3 surface can be generated by knot or link surgery in the manner of Fintushel and Stern. The results are applied to the calculation of expectation values. Here we discuss the two observables, volume and Wilson loop, for the construction of an exotic 4-manifold using the knot 52 and the Whitehead link Wh. By using Mostow rigidity, we obtain a topological contribution to the expectation value of the volume. Furthermore, we obtain a justification of area quantization.

  4. Microtubule-dependent motility and orientation of the cortical endoplasmic reticulum in elongating characean internodal cells.

    PubMed

    Foissner, Ilse; Menzel, Diedrik; Wasteneys, Geoffrey O

    2009-03-01

    Motility of the endoplasmic reticulum (ER) is predominantly microtubule- dependent in animal cells but thought to be entirely actomyosin-dependent in plant cells. Using live cell imaging and transmission electron microscopy to examine ER motility and structural organization in giant internodal cells of characean algae, we discovered that at the onset of cell elongation, the cortical ER situated near the plasma membrane formed a tight meshwork of predominantly transverse ER tubules that frequently coaligned with microtubules. Microtubule depolymerization increased mesh size and decreased the dynamics of the cortical ER. In contrast, perturbing the cortical actin array with cytochalasins did not affect the transverse orientation but decreased mesh size and increased ER dynamics. Our data suggest that myosin-dependent ER motility is confined to the ER strands in the streaming endoplasm, while the more sedate cortical ER uses microtubule-based mechanisms for organization and motility during early stages of cell elongation. We show further that the ER has an inherent, NEM-sensitive dynamics which can be altered via interaction with the cytoskeleton and that tubule formation and fusion events are cytoskeleton-independent.

  5. Nodular smooth muscle metaplasia in multiple peritoneal endometriosis.

    PubMed

    Kim, Hyun-Soo; Yoon, Gun; Ha, Sang Yun; Song, Sang Yong

    2015-01-01

    We report here an unusual presentation of peritoneal endometriosis with smooth muscle metaplasia as multiple protruding masses on the lateral pelvic wall. Smooth muscle metaplasia is a common finding in rectovaginal endometriosis, whereas in peritoneal endometriosis, smooth muscle metaplasia is uncommon and its nodular presentation on the pelvic wall is even rarer. To the best of our knowledge, this is the first case of nodular smooth muscle metaplasia occurring in peritoneal endometriosis. As observed in this case, when performing laparoscopic surgery in order to excise malignant tumors of intra-abdominal or pelvic organs, it can be difficult for surgeons to distinguish the metastatic tumors from benign nodular pelvic wall lesions, including endometriosis, based on the gross findings only. Therefore, an intraoperative frozen section biopsy of the pelvic wall nodules should be performed to evaluate the peritoneal involvement by malignant tumors. Moreover, this report implies that peritoneal endometriosis, as well as rectovaginal endometriosis, can clinically present as nodular lesions if obvious smooth muscle metaplasia is present. The pathological investigation of smooth muscle cells in peritoneal lesions can contribute not only to the precise diagnosis but also to the structure and function of smooth muscle cells and related cells involved in the histogenesis of peritoneal endometriosis.

  6. Smooth Tubercle Bacilli: Neglected Opportunistic Tropical Pathogens

    PubMed Central

    Aboubaker Osman, Djaltou; Bouzid, Feriel; Canaan, Stéphane; Drancourt, Michel

    2016-01-01

    Smooth tubercle bacilli (STB) including “Mycobacterium canettii” are members of the Mycobacterium tuberculosis complex (MTBC), which cause non-contagious tuberculosis in human. This group comprises <100 isolates characterized by smooth colonies and cordless organisms. Most STB isolates have been obtained from patients exposed to the Republic of Djibouti but seven isolates, including the three seminal ones obtained by Georges Canetti between 1968 and 1970, were recovered from patients in France, Madagascar, Sub-Sahara East Africa, and French Polynesia. STB form a genetically heterogeneous group of MTBC organisms with large 4.48 ± 0.05 Mb genomes, which may link Mycobacterium kansasii to MTBC organisms. Lack of inter-human transmission suggested a yet unknown environmental reservoir. Clinical data indicate a respiratory tract route of contamination and the digestive tract as an alternative route of contamination. Further epidemiological and clinical studies are warranted to elucidate areas of uncertainty regarding these unusual mycobacteria and the tuberculosis they cause. PMID:26793699

  7. Smooth Tubercle Bacilli: Neglected Opportunistic Tropical Pathogens.

    PubMed

    Aboubaker Osman, Djaltou; Bouzid, Feriel; Canaan, Stéphane; Drancourt, Michel

    2015-01-01

    Smooth tubercle bacilli (STB) including "Mycobacterium canettii" are members of the Mycobacterium tuberculosis complex (MTBC), which cause non-contagious tuberculosis in human. This group comprises <100 isolates characterized by smooth colonies and cordless organisms. Most STB isolates have been obtained from patients exposed to the Republic of Djibouti but seven isolates, including the three seminal ones obtained by Georges Canetti between 1968 and 1970, were recovered from patients in France, Madagascar, Sub-Sahara East Africa, and French Polynesia. STB form a genetically heterogeneous group of MTBC organisms with large 4.48 ± 0.05 Mb genomes, which may link Mycobacterium kansasii to MTBC organisms. Lack of inter-human transmission suggested a yet unknown environmental reservoir. Clinical data indicate a respiratory tract route of contamination and the digestive tract as an alternative route of contamination. Further epidemiological and clinical studies are warranted to elucidate areas of uncertainty regarding these unusual mycobacteria and the tuberculosis they cause. PMID:26793699

  8. Endoplasmic reticulum stress and proteasomal system in amyotrophic lateral sclerosis.

    PubMed

    Karademir, Betul; Corek, Ceyda; Ozer, Nesrin Kartal

    2015-11-01

    Protein processing including folding, unfolding and degradation is involved in the mechanisms of many diseases. Unfolded protein response and/or endoplasmic reticulum stress are accepted to be the first steps which should be completed via protein degradation. In this direction, proteasomal system and autophagy play important role as the degradation pathways and controlled via complex mechanisms. Amyotrophic lateral sclerosis is a multifactorial neurodegenerative disease which is also known as the most catastrophic one. Mutation of many different genes are involved in the pathogenesis such as superoxide dismutase 1, chromosome 9 open reading frame 72 and ubiquilin 2. These genes are mainly related to the antioxidant defense systems, endoplasmic reticulum stress related proteins and also protein aggregation, degradation pathways and therefore mutation of these genes cause related disorders.This review focused on the role of protein processing via endoplasmic reticulum and proteasomal system in amyotrophic lateral sclerosis which are the main players in the pathology. In this direction, dysfunction of endoplasmic reticulum associated degradation and related cell death mechanisms that are autophagy/apoptosis have been detailed.

  9. Pleomorphic rhabdomyosarcoma showing smooth-muscle and fibrohistiocytic differentiation: a single case report.

    PubMed

    Eyden, Brian

    2010-02-01

    Rhabdomyosarcoma has traditionally been subclassified into alveolar, embryonal, and pleomorphic variants. Less commonly, spindle-cell, neuroendocrine, sclerosing, and lipid-rich or clear-cell subtypes are seen. The author recently encountered a myogenic sarcoma, with all the common markers of rhabdomyosarcoma, but expressing the unusual features of alpha-smooth-muscle actin and abundant rough endoplasmic reticulum (rER). This myogenic sarcoma, therefore, exhibited four lines of differentiation, and is documented here. The patient was a 65-year-old man with an inguinal soft tissue mass. Following surgical excision, the patient was given radiotherapy and was well without disease after 6 years. The tumor was positive for vimentin, desmin, alpha-smooth-muscle actin, alpha-sarcomeric actin, myogenin, MyoD1, and CD68. Cytoplasm was dominated by abundant rER intermingled with lipid droplets and lysosomes. Cell surfaces exhibited microvillous processes and focal adhesions, but no lamina. Subplasmalemmal smooth-muscle-type myofilaments with focal densities and rare sarcomeric filaments were seen. The low level of expression of some markers was interpreted as consistent with a poorly differentiated tumor. Given the four lines of differentiation--striated muscle, smooth muscle, fibroblastic, and histiocytic--a name reflecting its phenotype would be pleomorphic rhabdomyosarcoma showing smooth-muscle and fibrohistiocytic differentiation. PMID:20070153

  10. Rheological properties of living cytoplasm: endoplasm of Physarum plasmodium.

    PubMed

    Sato, M; Wong, T Z; Allen, R D

    1983-10-01

    Magnetic sphere viscoelastometry, video microscopy, and the Kamiya double chamber method (Kamiya, N., 1940, Science [Wash. DC], 92:462-463.) have been combined in an optical and rheological investigation of the living endoplasm of Physarum polycephalum. The rheological properties examined were yield stress, viscosity (as a function of shear), and elasticity. These parameters were evaluated in directions perpendicular; (X) and parallel (Y) to the plasmodial vein. Known magnetic forces were used for measurements in the X direction, while the falling ball technique was used in the Y direction (Cygan, D.A., and B. Caswell, 1971, Trans. Soc. Rheol. 15:663-683; MacLean-Fletcher, S.D., and T.D. Pollard, 1980, J. Cell Biol., 85:414-428). Approximate yield stresses were calculated in the X and Y directions of 0.58 and 1.05 dyn/cm2, respectively. Apparent viscosities measured in the two directions (eta x and eta y) were found to fluctuate with time. The fluctuations in eta x and eta y were shown, statistically, to occur independently of each other. Frequency correlation with dynamoplasmograms indicated that these fluctuations probably occur independently of the streaming cycle. Viscosity was found to be a complex function of shear, indicating that the endoplasm is non-Newtonian. Plots of shear stress vs. rate of shear both parallel and perpendicular to the vein, showed that endoplasm is not a shear thinning material. These experiments have shown that living endoplasm of Physarum is an anisotropic viscoelastic fluid with a yield stress. The endoplasm appears not to be a homogeneous material, but to be composed of heterogeneous domains. PMID:6619187

  11. 7 CFR 51.768 - Smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Smooth texture. 51.768 Section 51.768 Agriculture... Standards for Grades of Florida Grapefruit Definitions § 51.768 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit. “Thin” means that the...

  12. 7 CFR 51.698 - Smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Smooth texture. 51.698 Section 51.698 Agriculture..., California, and Arizona) Definitions § 51.698 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  13. 7 CFR 51.1159 - Smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Smooth texture. 51.1159 Section 51.1159 Agriculture... Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1159 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  14. 7 CFR 51.636 - Smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Smooth texture. 51.636 Section 51.636 Agriculture... Florida, California, and Arizona) Definitions § 51.636 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  15. 7 CFR 51.636 - Smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Smooth texture. 51.636 Section 51.636 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...) Definitions § 51.636 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety...

  16. 7 CFR 51.1159 - Smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Smooth texture. 51.1159 Section 51.1159 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.1159 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety...

  17. 7 CFR 51.698 - Smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Smooth texture. 51.698 Section 51.698 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.698 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and...

  18. 7 CFR 51.698 - Smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Smooth texture. 51.698 Section 51.698 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.698 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and...

  19. 7 CFR 51.768 - Smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Smooth texture. 51.768 Section 51.768 Agriculture... Standards for Grades of Florida Grapefruit Definitions § 51.768 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit. “Thin” means that the...

  20. 7 CFR 51.768 - Smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Smooth texture. 51.768 Section 51.768 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of...

  1. 7 CFR 51.1159 - Smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Smooth texture. 51.1159 Section 51.1159 Agriculture... Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1159 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  2. 7 CFR 51.768 - Smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Smooth texture. 51.768 Section 51.768 Agriculture... Standards for Grades of Florida Grapefruit Definitions § 51.768 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit. “Thin” means that the...

  3. 7 CFR 51.698 - Smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Smooth texture. 51.698 Section 51.698 Agriculture..., California, and Arizona) Definitions § 51.698 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  4. 7 CFR 51.1159 - Smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Smooth texture. 51.1159 Section 51.1159 Agriculture... Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1159 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  5. 7 CFR 51.698 - Smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Smooth texture. 51.698 Section 51.698 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.698 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and...

  6. 7 CFR 51.636 - Smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Smooth texture. 51.636 Section 51.636 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...) Definitions § 51.636 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety...

  7. 7 CFR 51.636 - Smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Smooth texture. 51.636 Section 51.636 Agriculture... Florida, California, and Arizona) Definitions § 51.636 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit....

  8. 7 CFR 51.636 - Smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Smooth texture. 51.636 Section 51.636 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...) Definitions § 51.636 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety...

  9. 7 CFR 51.1159 - Smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Smooth texture. 51.1159 Section 51.1159 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... § 51.1159 Smooth texture. Smooth texture means that the skin is thin and smooth for the variety...

  10. Se Enhances MLCK Activation by Regulating Selenoprotein T (SelT) in the Gastric Smooth Muscle of Rats.

    PubMed

    Li, Jia-Ping; Zhou, Jing-Xuan; Wang, Qi; Gu, Gao-Qin; Yang, Shi-Jin; Li, Cheng-Ye; Qiu, Chang-Wei; Deng, Gan-Zhen; Guo, Meng-Yao

    2016-09-01

    Selenium (Se), a nutritionally essential trace element, is associated with health and disease. Selenoprotein T (SelT) was identified as a redoxin protein with a selenocystein, localizing in the endoplasmic reticulum. The myosin light chain kinase (MLCK) and myosin light chain (MLC) play key roles in the contraction process of smooth muscle. The present study was to detect the effect and mechanism of SelT on the contraction process of gastric smooth muscle. The WT rats were fed with different Se concentration diets, and Se and Ca(2+) concentrations were detected in the gastric smooth muscle. Western blot and qPCR were performed to determine SelT, CaM, MLCK, and MLC expressions. MLCK activity was measured by identifying the rates of [γ-32P]ATP incorporated into the MLC. The results showed Se and Ca(2+) concentrations were enhanced with Se intake in gastric smooth muscle tissues. With increasing Se, SelT, CaM, MLCK and MLC expressions increased, and MLCK and MLC activation improved in gastric smooth muscle tissue. The SelT RNA interference experiments showed that Ca(2+) release, MLCK activation, and MLC phosphorylation were regulated by SelT. Se affected the gastric smooth muscle constriction by regulating Ca(2+) release, MLCK activation, and MLC phosphorylation through SelT. Se plays a major role in regulating the contraction processes of gastric smooth muscle with the SelT.

  11. Clonogenic multipotent stem cells in human adipose tissue differentiate into functional smooth muscle cells

    PubMed Central

    Rodríguez, Larissa V.; Alfonso, Zeni; Zhang, Rong; Leung, Joanne; Wu, Benjamin; Ignarro, Louis J.

    2006-01-01

    Smooth muscle is a major component of human tissues and is essential for the normal function of a multitude of organs including the intestine, urinary tract and the vascular system. The use of stem cells for cell-based tissue engineering and regeneration strategies represents a promising alternative for smooth muscle repair. For such strategies to succeed, a reliable source of smooth muscle precursor cells must be identified. Adipose tissue provides an abundant source of multipotent cells. In this study, the capacity of processed lipoaspirate (PLA) and adipose-derived stem cells to differentiate into phenotypic and functional smooth muscle cells was evaluated. To induce differentiation, PLA cells were cultured in smooth muscle differentiation medium. Smooth muscle differentiation of PLA cells induced genetic expression of all smooth muscle markers and further confirmed by increased protein expression of smooth muscle cell-specific α actin (ASMA), calponin, caldesmon, SM22, myosin heavy chain (MHC), and smoothelin. Clonal studies of adipose derived multipotent cells demonstrated differentiation of these cells into smooth muscle cells in addition to trilineage differentiation capacity. Importantly, smooth muscle-differentiated cells, but not their precursors, exhibit the functional ability to contract and relax in direct response to pharmacologic agents. In conclusion, adipose-derived cells have the potential to differentiate into functional smooth muscle cells and, thus, adipose tissue can be a useful source of cells for treatment of injured tissues where smooth muscle plays an important role. PMID:16880387

  12. Respiratory metabolism and calorie restriction relieve persistent endoplasmic reticulum stress induced by calcium shortage in yeast.

    PubMed

    Busti, Stefano; Mapelli, Valeria; Tripodi, Farida; Sanvito, Rossella; Magni, Fulvio; Coccetti, Paola; Rocchetti, Marcella; Nielsen, Jens; Alberghina, Lilia; Vanoni, Marco

    2016-06-16

    Calcium homeostasis is crucial to eukaryotic cell survival. By acting as an enzyme cofactor and a second messenger in several signal transduction pathways, the calcium ion controls many essential biological processes. Inside the endoplasmic reticulum (ER) calcium concentration is carefully regulated to safeguard the correct folding and processing of secretory proteins. By using the model organism Saccharomyces cerevisiae we show that calcium shortage leads to a slowdown of cell growth and metabolism. Accumulation of unfolded proteins within the calcium-depleted lumen of the endoplasmic reticulum (ER stress) triggers the unfolded protein response (UPR) and generates a state of oxidative stress that decreases cell viability. These effects are severe during growth on rapidly fermentable carbon sources and can be mitigated by decreasing the protein synthesis rate or by inducing cellular respiration. Calcium homeostasis, protein biosynthesis and the unfolded protein response are tightly intertwined and the consequences of facing calcium starvation are determined by whether cellular energy production is balanced with demands for anabolic functions. Our findings confirm that the connections linking disturbance of ER calcium equilibrium to ER stress and UPR signaling are evolutionary conserved and highlight the crucial role of metabolism in modulating the effects induced by calcium shortage.

  13. Respiratory metabolism and calorie restriction relieve persistent endoplasmic reticulum stress induced by calcium shortage in yeast

    PubMed Central

    Busti, Stefano; Mapelli, Valeria; Tripodi, Farida; Sanvito, Rossella; Magni, Fulvio; Coccetti, Paola; Rocchetti, Marcella; Nielsen, Jens; Alberghina, Lilia; Vanoni, Marco

    2016-01-01

    Calcium homeostasis is crucial to eukaryotic cell survival. By acting as an enzyme cofactor and a second messenger in several signal transduction pathways, the calcium ion controls many essential biological processes. Inside the endoplasmic reticulum (ER) calcium concentration is carefully regulated to safeguard the correct folding and processing of secretory proteins. By using the model organism Saccharomyces cerevisiae we show that calcium shortage leads to a slowdown of cell growth and metabolism. Accumulation of unfolded proteins within the calcium-depleted lumen of the endoplasmic reticulum (ER stress) triggers the unfolded protein response (UPR) and generates a state of oxidative stress that decreases cell viability. These effects are severe during growth on rapidly fermentable carbon sources and can be mitigated by decreasing the protein synthesis rate or by inducing cellular respiration. Calcium homeostasis, protein biosynthesis and the unfolded protein response are tightly intertwined and the consequences of facing calcium starvation are determined by whether cellular energy production is balanced with demands for anabolic functions. Our findings confirm that the connections linking disturbance of ER calcium equilibrium to ER stress and UPR signaling are evolutionary conserved and highlight the crucial role of metabolism in modulating the effects induced by calcium shortage. PMID:27305947

  14. Relevance of Endoplasmic Reticulum Stress Cell Signaling in Liver Cold Ischemia Reperfusion Injury

    PubMed Central

    Folch-Puy, Emma; Panisello, Arnau; Oliva, Joan; Lopez, Alexandre; Castro Benítez, Carlos; Adam, René; Roselló-Catafau, Joan

    2016-01-01

    The endoplasmic reticulum (ER) is involved in calcium homeostasis, protein folding and lipid biosynthesis. Perturbations in its normal functions lead to a condition called endoplasmic reticulum stress (ERS). This can be triggered by many physiopathological conditions such as alcoholic steatohepatitis, insulin resistance or ischemia-reperfusion injury. The cell reacts to ERS by initiating a defensive process known as the unfolded protein response (UPR), which comprises cellular mechanisms for adaptation and the safeguarding of cell survival or, in cases of excessively severe stress, for the initiation of the cell death program. Recent experimental data suggest the involvement of ERS in ischemia/reperfusion injury (IRI) of the liver graft, which has been considered as one of major problems influencing outcome after liver transplantation. The purpose of this review is to summarize updated data on the molecular mechanisms of ERS/UPR and the consequences of this pathology, focusing specifically on solid organ preservation and liver transplantation models. We will also discuss the potential role of ERS, beyond the simple adaptive response and the regulation of cell death, in the modification of cell functional properties and phenotypic changes. PMID:27231901

  15. Relevance of Endoplasmic Reticulum Stress Cell Signaling in Liver Cold Ischemia Reperfusion Injury.

    PubMed

    Folch-Puy, Emma; Panisello, Arnau; Oliva, Joan; Lopez, Alexandre; Castro Benítez, Carlos; Adam, René; Roselló-Catafau, Joan

    2016-01-01

    The endoplasmic reticulum (ER) is involved in calcium homeostasis, protein folding and lipid biosynthesis. Perturbations in its normal functions lead to a condition called endoplasmic reticulum stress (ERS). This can be triggered by many physiopathological conditions such as alcoholic steatohepatitis, insulin resistance or ischemia-reperfusion injury. The cell reacts to ERS by initiating a defensive process known as the unfolded protein response (UPR), which comprises cellular mechanisms for adaptation and the safeguarding of cell survival or, in cases of excessively severe stress, for the initiation of the cell death program. Recent experimental data suggest the involvement of ERS in ischemia/reperfusion injury (IRI) of the liver graft, which has been considered as one of major problems influencing outcome after liver transplantation. The purpose of this review is to summarize updated data on the molecular mechanisms of ERS/UPR and the consequences of this pathology, focusing specifically on solid organ preservation and liver transplantation models. We will also discuss the potential role of ERS, beyond the simple adaptive response and the regulation of cell death, in the modification of cell functional properties and phenotypic changes. PMID:27231901

  16. Registration of 'Newell' Smooth Bromegrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Newell’ (Reg. No. CV-xxxx, PI 671851) smooth bromegrass (Bromus inermis Leyss.) is a steppe or southern type cultivar that is primarily adapted in the USA to areas north of 40o N lat. and east of 100o W long. that have 500 mm or more annual precipitation or in areas that have similar climate cond...

  17. Surface antigens of smooth brucellae.

    PubMed

    Diaz, R; Jones, L M; Leong, D; Wilson, J B

    1968-10-01

    Surface antigens of smooth brucellae were extracted by ether-water, phenol-water, trichloroacetic acid, and saline and examined by immunoelectrophoresis and gel diffusion with antisera from infected and immunized rabbits. Ether-water extracts of Brucella melitensis contained a lipopolysaccharide protein component, which was specific for the surface of smooth brucellae and was correlated with the M agglutinogen of Wilson and Miles, a polysaccharide protein component devoid of lipid which was not restricted to the surface of smooth brucellae and was not correlated with the smooth agglutinogen (component 1), and several protein components which were associated with internal antigens of rough and smooth brucellae. Immunoelectrophoretic analysis of ether-water extracts of B. abortus revealed only two components, a lipopolysaccharide protein component, which was correlated with the A agglutinogen, and component 1. Component 1 from B. melitensis and B. abortus showed identity in gel diffusion tests, whereas component M from B. melitensis and component A from B. abortus showed partial identity with unabsorbed antisera and no cross-reactions with monospecific sera. Attempts to prepare monospecific sera directly by immunization of rabbits with cell walls or ether-water extracts were unsuccessful. Absorption of antisera with heavy fraction of ether-water extracts did not always result in monospecific sera. It was concluded (as has been described before) that the A and M antigens are present on a single antigenic complex, in different proportions depending upon the species and biotype, and that this component is a lipopolysaccharide protein complex of high molecular weight that diffuses poorly through agar gel. Components 1, A, and M were also demonstrated in trichloroacetic acid and phenol-water extracts. With all extracts, B. melitensis antigen showed greater diffusibility in agar than B. abortus antigens. After mild acid hydrolysis, B. abortus ether-water extract was able

  18. ER reorganization is remarkably induced in COS-7 cells accumulating transmembrane protein receptors not competent for export from the endoplasmic reticulum.

    PubMed

    D'Agostino, Massimo; Crespi, Arianna; Polishchuk, Elena; Generoso, Serena; Martire, Gianluca; Colombo, Sara Francesca; Bonatti, Stefano

    2014-11-01

    The newly synthesized mutant L501fsX533 Frizzled-4 form and the alpha3beta4 nicotinic acetylcholine receptor expressed in the absence of nicotine accumulate in the endoplasmic reticulum of COS-7 cells and induce the formation of large areas of smooth and highly convoluted cisternae. This results in a generalized block of the transport to the Golgi complex of newly synthesized proteins. Intriguingly, both effects happen peculiarly in COS-7 cells; HeLa, Huh-7, and HEK293 cells expressing the two receptors at similar level than COS-7 cells show normal ER and normal transport toward the plasma membrane. These results question the conclusion that a dominant-negative mechanism would explain the dominance of the mutant L501fsX533 Fz4 allele in the transmission of a form of Familial exudative vitreoretinopathy. Moreover, they indicate that the coordination of endoplasmic reticulum homeostasis in COS-7 cells is particularly error prone. This finding suggests that COS-7 cells may be extremely useful to study the molecular mechanisms regulating endoplasmic reticulum size and architecture.

  19. Smoothed particle hydrodynamics with smoothed pseudo-density

    NASA Astrophysics Data System (ADS)

    Yamamoto, Satoko; Saitoh, Takayuki R.; Makino, Junichiro

    2015-06-01

    In this paper, we present a new formulation of smoothed particle hydrodynamics (SPH), which, unlike the standard SPH (SSPH), is well behaved at the contact discontinuity. The SSPH scheme cannot handle discontinuities in density (e.g., the contact discontinuity and the free surface), because it requires that the density of fluid is positive and continuous everywhere. Thus there is inconsistency in the formulation of the SSPH scheme at discontinuities of the fluid density. To solve this problem, we introduce a new quantity associated with particles and the "density" of that quantity. This "density" evolves through the usual continuity equation with an additional artificial diffusion term, in order to guarantee the continuity of the "density." We use this "density," or pseudo-density, instead of the mass density, to formulate our SPH scheme. We call our new method SPH with smoothed pseudo-density, and we show that it is physically consistent and can handle discontinuities quite well.

  20. Endoplasmic reticulum quality control in cancer: friend or foe

    PubMed Central

    Kim, Hana; Bhattacharya, Asmita; Qi, Ling

    2015-01-01

    Quality control systems in the endoplasmic reticulum (ER) mediated by unfolded protein response (UPR) and endoplasmic reticulum associated degradation (ERAD) ensure cellular function and organismal survival. Recent studies have suggested that ER quality-control systems in cancer cells may serve as a double-edged sword that aids progression as well as prevention of tumor growth in a context-dependent manner. Here we review recent advances in our understanding of the complex relationship between ER proteostasis and cancer pathology, with a focus on the two most conserved ER quality-control mechanisms – the IRE1α-XBP1 pathway of the UPR and SEL1L-HRD1 complex of the ERAD. PMID:25794824

  1. From endoplasmic-reticulum stress to the inflammatory response

    PubMed Central

    Zhang, Kezhong; Kaufman, Randal J.

    2009-01-01

    The endoplasmic reticulum is responsible for much of a cell’s protein synthesis and folding, but it also has an important role in sensing cellular stress. Recently, it has been shown that the endoplasmic reticulum mediates a specific set of intracellular signalling pathways in response to the accumulation of unfolded or misfolded proteins, and these pathways are collectively known as the unfolded-protein response. New observations suggest that the unfolded-protein response can initiate inflammation, and the coupling of these responses in specialized cells and tissues is now thought to be fundamental in the pathogenesis of inflammatory diseases. The knowledge gained from this emerging field will aid in the development of therapies for modulating cellular stress and inflammation. PMID:18650916

  2. Endoplasmic reticulum stress in mouse decidua during early pregnancy.

    PubMed

    Gu, Xiao-Wei; Yan, Jia-Qi; Dou, Hai-Ting; Liu, Jie; Liu, Li; Zhao, Meng-Long; Liang, Xiao-Huan; Yang, Zeng-Ming

    2016-10-15

    Unfolded or misfolded protein accumulation in the endoplasmic reticulum lumen leads to endoplasmic reticulum stress (ER stress). Although it is known that ER stress is crucial for mammalian reproduction, little is known about its physiological significance and underlying mechanism during decidualization. Here we show that Ire-Xbp1 signal transduction pathway of unfolded protein response (UPR) is activated in decidual cells. The process of decidualization is compromised by ER stress inhibitor tauroursodeoxycholic acid sodium (TUDCA) and Ire specific inhibitor STF-083010 both in vivo and in vitro. A high concentration of ER stress inducer tunicamycin (TM) suppresses stromal cells proliferation and decidualization, while a lower concentration is beneficial. We further show that ER stress induces DNA damage and polyploidization in stromal cells. In conclusion, our data suggest that the GRP78/Ire1/Xbp1 signaling pathway of ER stress-UPR is activated and involved in mouse decidualization.

  3. Quantitative Proteomics and Lipidomics Analysis of Endoplasmic Reticulum of Macrophage Infected with Mycobacterium tuberculosis

    PubMed Central

    Saquib, Najmuddin Mohd; Jamwal, Shilpa; Midha, Mukul Kumar; Verma, Hirdya Narain; Manivel, Venkatasamy

    2015-01-01

    Even though endoplasmic reticulum (ER) stress associated with mycobacterial infection has been well studied, the molecular basis of ER as a crucial organelle to determine the fate of Mtb is yet to be established. Here, we have studied the ability of Mtb to manipulate the ultrastructural architecture of macrophage ER and found that the ER-phenotypes associated with virulent (H37Rv) and avirulent (H37Ra) strains were different: a rough ER (RER) with the former against a smooth ER (SER) with the later. Further, the functional attributes of these changes were probed by MS-based quantitative proteomics (133 ER proteins) and lipidomics (8 phospholipids). Our omics approaches not only revealed the host pathogen cross-talk but also emphasized how precisely Mtb uses proteins and lipids in combination to give rise to characteristic ER-phenotypes. H37Ra-infected macrophages increased the cytosolic Ca2+ levels by attenuating the ATP2A2 protein and simultaneous induction of PC/PE expression to facilitate apoptosis. However, H37Rv inhibited apoptosis and further controlled the expression of EST-1 and AMRP proteins to disturb cholesterol homeostasis resulting in sustained infection. This approach offers the potential to decipher the specific roles of ER in understanding the cell biology of mycobacterial infection with special reference to the impact of host response. PMID:25785198

  4. Reduction of endoplasmic reticulum stress inhibits neointima formation after vascular injury.

    PubMed

    Ishimura, Shutaro; Furuhashi, Masato; Mita, Tomohiro; Fuseya, Takahiro; Watanabe, Yuki; Hoshina, Kyoko; Kokubu, Nobuaki; Inoue, Katsumi; Yoshida, Hideaki; Miura, Tetsuji

    2014-11-06

    Endoplasmic reticulum (ER) stress and inappropriate adaptation through the unfolded protein response (UPR) are predominant features of pathological processes. However, little is known about the link between ER stress and endovascular injury. We investigated the involvement of ER stress in neointima hyperplasia after vascular injury. The femoral arteries of 7-8-week-old male mice were subjected to wire-induced vascular injury. After 4 weeks, immunohistological analysis showed that ER stress markers were upregulated in the hyperplastic neointima. Neointima formation was increased by 54.8% in X-box binding protein-1 (XBP1) heterozygous mice, a model of compromised UPR. Knockdown of Xbp1 in human coronary artery smooth muscle cells (CASMC) in vitro promoted cell proliferation and migration. Furthermore, treatment with ER stress reducers, 4-phenylbutyrate (4-PBA) and tauroursodeoxycholic acid (TUDCA), decreased the intima-to-media ratio after wire injury by 50.0% and 72.8%, respectively. Chronic stimulation of CASMC with PDGF-BB activated the UPR, and treatment with 4-PBA and TUDCA significantly suppressed the PDGF-BB-induced ER stress markers in CASMC and the proliferation and migration of CASMC. In conclusion, increased ER stress contributes to neointima formation after vascular injury, while UPR signaling downstream of XBP1 plays a suppressive role. Suppression of ER stress would be a novel strategy against post-angioplasty vascular restenosis.

  5. Further assembly required: construction and dynamics of the endoplasmic reticulum network.

    PubMed

    Park, Seong H; Blackstone, Craig

    2010-07-01

    The endoplasmic reticulum (ER) is a continuous membrane system comprising the nuclear envelope, ribosome-studded peripheral sheets and an interconnected network of smooth tubules extending throughout the cell. Although protein biosynthesis, transport and quality control in the ER have been studied extensively, mechanisms underlying the notably diverse architecture of the ER have only emerged recently; this review highlights these new findings and how they relate to ER functional specializations. Several protein families, including reticulons and DP1/REEPs/Yop1, harbour hydrophobic hairpin domains that shape high-curvature ER tubules and mediate intramembrane protein interactions. Members of the atlastin/RHD3/Sey1 family of dynamin-related GTPases mediate the formation of three-way junctions that characterize the tubular ER network, and additional classes of hydrophobic hairpin-containing ER proteins interact with and remodel the microtubule cytoskeleton. Flat ER sheets have a different complement of proteins implicated in shaping, cisternal stacking and microtubule interactions. Finally, several shaping proteins are mutated in hereditary spastic paraplegias, emphasizing the particular importance of proper ER morphology and distribution for highly polarized cells. PMID:20559323

  6. Young Craters on Smooth Plains

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Young craters (the largest of which is about 100 kilometers in diameter) superposed on smooth plains. Larger young craters have central peaks, flat floors, terraced walls, radial ejecta deposits, and surrounding fields of secondary craters. Smooth plains have well-developed ridges extending NW and NE. This image (FDS 167), acquired during the spacecraft's first encounter with Mercury, is located approximately 60 degrees N, 175 degrees W.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    Image Credit: NASA/JPL/Northwestern University

  7. Smoothing of mixed complementarity problems

    SciTech Connect

    Gabriel, S.A.; More, J.J.

    1995-09-01

    The authors introduce a smoothing approach to the mixed complementarity problem, and study the limiting behavior of a path defined by approximate minimizers of a nonlinear least squares problem. The main result guarantees that, under a mild regularity condition, limit points of the iterates are solutions to the mixed complementarity problem. The analysis is applicable to a wide variety of algorithms suitable for large-scale mixed complementarity problems.

  8. Regulation of calcium and phosphoinositides at endoplasmic reticulum-membrane junctions.

    PubMed

    Dickson, Eamonn J; Jensen, Jill B; Hille, Bertil

    2016-04-15

    Effective cellular function requires both compartmentalization of tasks in space and time, and coordination of those efforts. The endoplasmic reticulum's (ER) expansive and ramifying structure makes it ideally suited to serve as a regulatory platform for organelle-organelle communication through membrane contacts. These contact sites consist of two membranes juxtaposed at a distance less than 30 nm that mediate the exchange of lipids and ions without the need for membrane fission or fusion, a process distinct from classical vesicular transport. Membrane contact sites are positioned by organelle-specific membrane-membrane tethering proteins and contain a growing number of additional proteins that organize information transfer to shape membrane identity. Here we briefly review the role of ER-containing membrane junctions in two important cellular functions: calcium signalling and phosphoinositide processing. PMID:27068956

  9. Sc65-Null Mice Provide Evidence for a Novel Endoplasmic Reticulum Complex Regulating Collagen Lysyl Hydroxylation

    PubMed Central

    Weis, MaryAnn; Rai, Jyoti; Hudson, David M.; Dimori, Milena; Zimmerman, Sarah M.; Hogue, William R.; Swain, Frances L.; Burdine, Marie S.; Mackintosh, Samuel G.; Tackett, Alan J.; Suva, Larry J.; Eyre, David R.

    2016-01-01

    Collagen is a major component of the extracellular matrix and its integrity is essential for connective tissue and organ function. The importance of proteins involved in intracellular collagen post-translational modification, folding and transport was recently highlighted from studies on recessive forms of osteogenesis imperfecta (OI). Here we describe the critical role of SC65 (Synaptonemal Complex 65, P3H4), a leprecan-family member, as part of an endoplasmic reticulum (ER) complex with prolyl 3-hydroxylase 3. This complex affects the activity of lysyl-hydroxylase 1 potentially through interactions with the enzyme and/or cyclophilin B. Loss of Sc65 in the mouse results in instability of this complex, altered collagen lysine hydroxylation and cross-linking leading to connective tissue defects that include low bone mass and skin fragility. This is the first indication of a prolyl-hydroxylase complex in the ER controlling lysyl-hydroxylase activity during collagen synthesis. PMID:27119146

  10. Sc65-Null Mice Provide Evidence for a Novel Endoplasmic Reticulum Complex Regulating Collagen Lysyl Hydroxylation.

    PubMed

    Heard, Melissa E; Besio, Roberta; Weis, MaryAnn; Rai, Jyoti; Hudson, David M; Dimori, Milena; Zimmerman, Sarah M; Kamykowski, Jeffrey A; Hogue, William R; Swain, Frances L; Burdine, Marie S; Mackintosh, Samuel G; Tackett, Alan J; Suva, Larry J; Eyre, David R; Morello, Roy

    2016-04-01

    Collagen is a major component of the extracellular matrix and its integrity is essential for connective tissue and organ function. The importance of proteins involved in intracellular collagen post-translational modification, folding and transport was recently highlighted from studies on recessive forms of osteogenesis imperfecta (OI). Here we describe the critical role of SC65 (Synaptonemal Complex 65, P3H4), a leprecan-family member, as part of an endoplasmic reticulum (ER) complex with prolyl 3-hydroxylase 3. This complex affects the activity of lysyl-hydroxylase 1 potentially through interactions with the enzyme and/or cyclophilin B. Loss of Sc65 in the mouse results in instability of this complex, altered collagen lysine hydroxylation and cross-linking leading to connective tissue defects that include low bone mass and skin fragility. This is the first indication of a prolyl-hydroxylase complex in the ER controlling lysyl-hydroxylase activity during collagen synthesis.

  11. Organizations.

    ERIC Educational Resources Information Center

    Aviation/Space, 1980

    1980-01-01

    This is a list of aerospace organizations and other groups that provides educators with assistance and information in specific areas. Both government and nongovernment organizations are included. (Author/SA)

  12. 7 CFR 51.768 - Smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Smooth texture. Smooth texture means that the skin is thin and smooth for the variety and size of the fruit. “Thin” means that the skin thickness does not average more than 3/8 inch (9.5 mm), on a...

  13. 7 CFR 51.1870 - Fairly smooth.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth. 51.1870 Section 51.1870 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Fresh Tomatoes 1 Definitions § 51.1870 Fairly smooth. Fairly smooth means that the tomato...

  14. 7 CFR 51.1870 - Fairly smooth.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Fairly smooth. 51.1870 Section 51.1870 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Fresh Tomatoes 1 Definitions § 51.1870 Fairly smooth. Fairly smooth means that the tomato is not conspicuously ridged or rough....

  15. 7 CFR 51.1910 - Fairly smooth.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth. 51.1910 Section 51.1910 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Consumer Standards for Fresh Tomatoes Definitions § 51.1910 Fairly smooth. Fairly smooth means that...

  16. 7 CFR 51.1870 - Fairly smooth.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fairly smooth. 51.1870 Section 51.1870 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Fresh Tomatoes 1 Definitions § 51.1870 Fairly smooth. Fairly smooth means that the tomato is not conspicuously ridged or rough....

  17. 7 CFR 51.1870 - Fairly smooth.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth. 51.1870 Section 51.1870 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Fresh Tomatoes 1 Definitions § 51.1870 Fairly smooth. Fairly smooth means that the tomato...

  18. 7 CFR 51.1870 - Fairly smooth.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly smooth. 51.1870 Section 51.1870 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Fresh Tomatoes 1 Definitions § 51.1870 Fairly smooth. Fairly smooth means that the tomato...

  19. 7 CFR 51.1910 - Fairly smooth.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth. 51.1910 Section 51.1910 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Consumer Standards for Fresh Tomatoes Definitions § 51.1910 Fairly smooth. Fairly smooth means that...

  20. 7 CFR 51.1910 - Fairly smooth.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Fairly smooth. 51.1910 Section 51.1910 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... smooth. Fairly smooth means that the tomato is not conspicuously ridged or rough....

  1. 7 CFR 51.1910 - Fairly smooth.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fairly smooth. 51.1910 Section 51.1910 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... smooth. Fairly smooth means that the tomato is not conspicuously ridged or rough....

  2. 7 CFR 51.1910 - Fairly smooth.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly smooth. 51.1910 Section 51.1910 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Consumer Standards for Fresh Tomatoes Definitions § 51.1910 Fairly smooth. Fairly smooth means that...

  3. A SAS IML Macro for Loglinear Smoothing

    ERIC Educational Resources Information Center

    Moses, Tim; von Davier, Alina

    2011-01-01

    Polynomial loglinear models for one-, two-, and higher-way contingency tables have important applications to measurement and assessment. They are essentially regarded as a smoothing technique, which is commonly referred to as loglinear smoothing. A SAS IML (SAS Institute, 2002a) macro was created to implement loglinear smoothing according to…

  4. Beamline smoothing of the Advanced Photon Source

    SciTech Connect

    Friedsam, H.; Penicka, M.; Zhao, S.

    1995-06-01

    This paper outlines a general beamline smoothing concept based on the use of First Principle Component analysis. Bean-dine smoothing is commonly used for the detection of blunders in the positioning of beam elements and to provide a smooth particle beam path with the fewest adjustments to individual beam components. It also provides the data for assessment of the achieved positioning quality.

  5. Smooth metrics for snapping strings

    NASA Astrophysics Data System (ADS)

    Gregory, Ruth; Hindmarsh, Mark

    1995-11-01

    We construct two possible metrics for Abelian Higgs vortices with ends on black holes. We show how the detail of the vortex fields smooths out the nodal singularities which exist in the idealized metrics. A corollary is that apparently topologically stable strings might be able to split by black hole pair production. We estimate the rate per unit length by reference to related Ernst and C-metric instantons, concluding that it is completely negligible for GUT-scale strings. The estimated rate for macroscopic superstrings is much higher, although still extremely small, unless there is an early phase of strong coupling.

  6. Smooth halos in the cosmic web

    NASA Astrophysics Data System (ADS)

    Gaite, José

    2015-04-01

    Dark matter halos can be defined as smooth distributions of dark matter placed in a non-smooth cosmic web structure. This definition of halos demands a precise definition of smoothness and a characterization of the manner in which the transition from smooth halos to the cosmic web takes place. We introduce entropic measures of smoothness, related to measures of inequality previously used in economy and with the advantage of being connected with standard methods of multifractal analysis already used for characterizing the cosmic web structure in cold dark matter N-body simulations. These entropic measures provide us with a quantitative description of the transition from the small scales portrayed as a distribution of halos to the larger scales portrayed as a cosmic web and, therefore, allow us to assign definite sizes to halos. However, these ``smoothness sizes'' have no direct relation to the virial radii. Finally, we discuss the influence of N-body discreteness parameters on smoothness.

  7. Smooth halos in the cosmic web

    SciTech Connect

    Gaite, José

    2015-04-01

    Dark matter halos can be defined as smooth distributions of dark matter placed in a non-smooth cosmic web structure. This definition of halos demands a precise definition of smoothness and a characterization of the manner in which the transition from smooth halos to the cosmic web takes place. We introduce entropic measures of smoothness, related to measures of inequality previously used in economy and with the advantage of being connected with standard methods of multifractal analysis already used for characterizing the cosmic web structure in cold dark matter N-body simulations. These entropic measures provide us with a quantitative description of the transition from the small scales portrayed as a distribution of halos to the larger scales portrayed as a cosmic web and, therefore, allow us to assign definite sizes to halos. However, these ''smoothness sizes'' have no direct relation to the virial radii. Finally, we discuss the influence of N-body discreteness parameters on smoothness.

  8. Standard-smooth hybrid inflation

    SciTech Connect

    Lazarides, George; Vamvasakis, Achilleas

    2007-12-15

    We consider the extended supersymmetric Pati-Salam model which, for {mu}>0 and universal boundary conditions, succeeds to yield experimentally acceptable b-quark masses by moderately violating Yukawa unification. It is known that this model can lead to new shifted or new smooth hybrid inflation. We show that a successful two-stage inflationary scenario can be realized within this model based only on renormalizable superpotential interactions. The cosmological scales exit the horizon during the first stage of inflation, which is of the standard hybrid type and takes place along the trivial flat direction with the inflaton driven by radiative corrections. Spectral indices compatible with the recent data can be achieved in global supersymmetry or minimal supergravity by restricting the number of e-foldings of our present horizon during the first inflationary stage. The additional e-foldings needed for solving the horizon and flatness problems are naturally provided by a second stage of inflation, which occurs mainly along the built-in new smooth hybrid inflationary path appearing right after the destabilization of the trivial flat direction at its critical point. Monopoles are formed at the end of the first stage of inflation and are, subsequently, diluted by the second stage of inflation to become utterly negligible in the present universe for almost all (for all) the allowed values of the parameters in the case of global supersymmetry (minimal supergravity)

  9. One step at a time: endoplasmic reticulum-associated degradation

    PubMed Central

    Vembar, Shruthi S.; Brodsky, Jeffrey L.

    2009-01-01

    Protein folding in the endoplasmic reticulum (ER) is monitored by ER quality control (ERQC) mechanisms. Proteins that pass ERQC criteria traffic to their final destinations through the secretory pathway, whereas non-native and unassembled subunits of multimeric proteins are degraded by the ER-associated degradation (ERAD) pathway. During ERAD, molecular chaperones and associated factors recognize and target substrates for retrotranslocation to the cytoplasm, where they are degraded by the ubiquitin–proteasome machinery. The discovery of diseases that are associated with ERAD substrates highlights the importance of this pathway. Here, we summarize our current understanding of each step during ERAD, with emphasis on the factors that catalyse distinct activities. PMID:19002207

  10. Endoplasmic Reticulum Stress and the Inflammatory Basis of Metabolic Disease

    PubMed Central

    Hotamisligil, Gökhan S.

    2010-01-01

    The endoplasmic reticulum (ER) is the major site in the cell for protein folding and trafficking and is central to many cellular functions. Failure of the ER's adaptive capacity results in activation of the unfolded protein response (UPR), which intersects with many different inflammatory and stress signaling pathways. These pathways are also critical in chronic metabolic diseases such as obesity, insulin resistance, and type 2 diabetes. The ER and related signaling networks are emerging as a potential site for the intersection of inflammation and metabolic disease. PMID:20303879

  11. Organics.

    ERIC Educational Resources Information Center

    Chian, Edward S. K.; DeWalle, Foppe B.

    1978-01-01

    Presents water analysis literature for 1978. This review is concerned with organics, and it covers: (1) detergents and surfactants; (2) aliphatic and aromatic hydrocarbons; (3) pesticides and chlorinated hydrocarbons; and (4) naturally occurring organics. A list of 208 references is also presented. (HM)

  12. Organizers.

    ERIC Educational Resources Information Center

    Callison, Daniel

    2000-01-01

    Focuses on "organizers," tools or techniques that provide identification and classification along with possible relationships or connections among ideas, concepts, and issues. Discusses David Ausubel's research and ideas concerning advance organizers; the implications of Ausubel's theory to curriculum and teaching; "webbing," a specific…

  13. ILDR2: an endoplasmic reticulum resident molecule mediating hepatic lipid homeostasis.

    PubMed

    Watanabe, Kazuhisa; Watson, Elizabeth; Cremona, Maria Laura; Millings, Elizabeth J; Lefkowitch, Jay H; Fischer, Stuart G; LeDuc, Charles A; Leibel, Rudolph L

    2013-01-01

    Ildr2, a modifier of diabetes susceptibility in obese mice, is expressed in most organs, including islets and hypothalamus, with reduced levels in livers of diabetes-susceptible B6.DBA mice congenic for a 1.8 Mb interval of Chromosome 1. In hepatoma and neuronal cells, ILDR2 is primarily located in the endoplasmic reticulum membrane. We used adenovirus vectors that express shRNA or are driven by the CMV promoter, respectively, to knockdown or overexpress Ildr2 in livers of wild type and ob/ob mice. Livers in knockdown mice were steatotic, with increased hepatic and circulating triglycerides and total cholesterol. Increased circulating VLDL, without reduction in triglyceride clearance suggests an effect of reduced hepatic ILDR2 on hepatic cholesterol clearance. In animals that overexpress Ildr2, hepatic triglyceride and total cholesterol levels were reduced, and strikingly so in ob/ob mice. There were no significant changes in body weight, energy expenditure or glucose/insulin homeostasis in knockdown or overexpressing mice. Knockdown mice showed reduced expression of genes mediating synthesis and oxidation of hepatic lipids, suggesting secondary suppression in response to increased hepatic lipid content. In Ildr2-overexpressing ob/ob mice, in association with reduced liver fat content, levels of transcripts related to neutral lipid synthesis and cholesterol were increased, suggesting "relief" of the secondary suppression imposed by lipid accumulation. Considering the fixed location of ILDR2 in the endoplasmic reticulum, we investigated the possible participation of ILDR2 in ER stress responses. In general, Ildr2 overexpression was associated with increases, and knockdown with decreases in levels of expression of molecular components of canonical ER stress pathways. We conclude that manipulation of Ildr2 expression in liver affects both lipid homeostasis and ER stress pathways. Given these reciprocal interactions, and the relatively extended time-course over which

  14. ILDR2: An Endoplasmic Reticulum Resident Molecule Mediating Hepatic Lipid Homeostasis

    PubMed Central

    Watanabe, Kazuhisa; Millings, Elizabeth J.; Lefkowitch, Jay H.; Fischer, Stuart G.; LeDuc, Charles A.; Leibel, Rudolph L.

    2013-01-01

    Ildr2, a modifier of diabetes susceptibility in obese mice, is expressed in most organs, including islets and hypothalamus, with reduced levels in livers of diabetes-susceptible B6.DBA mice congenic for a 1.8 Mb interval of Chromosome 1. In hepatoma and neuronal cells, ILDR2 is primarily located in the endoplasmic reticulum membrane. We used adenovirus vectors that express shRNA or are driven by the CMV promoter, respectively, to knockdown or overexpress Ildr2 in livers of wild type and ob/ob mice. Livers in knockdown mice were steatotic, with increased hepatic and circulating triglycerides and total cholesterol. Increased circulating VLDL, without reduction in triglyceride clearance suggests an effect of reduced hepatic ILDR2 on hepatic cholesterol clearance. In animals that overexpress Ildr2, hepatic triglyceride and total cholesterol levels were reduced, and strikingly so in ob/ob mice. There were no significant changes in body weight, energy expenditure or glucose/insulin homeostasis in knockdown or overexpressing mice. Knockdown mice showed reduced expression of genes mediating synthesis and oxidation of hepatic lipids, suggesting secondary suppression in response to increased hepatic lipid content. In Ildr2-overexpressing ob/ob mice, in association with reduced liver fat content, levels of transcripts related to neutral lipid synthesis and cholesterol were increased, suggesting “relief” of the secondary suppression imposed by lipid accumulation. Considering the fixed location of ILDR2 in the endoplasmic reticulum, we investigated the possible participation of ILDR2 in ER stress responses. In general, Ildr2 overexpression was associated with increases, and knockdown with decreases in levels of expression of molecular components of canonical ER stress pathways. We conclude that manipulation of Ildr2 expression in liver affects both lipid homeostasis and ER stress pathways. Given these reciprocal interactions, and the relatively extended time-course over

  15. The Cdc48 machine in endoplasmic reticulum associated protein degradation.

    PubMed

    Wolf, Dieter H; Stolz, Alexandra

    2012-01-01

    The AAA-type ATPase Cdc48 (named p97/VCP in mammals) is a molecular machine in all eukaryotic cells that transforms ATP hydrolysis into mechanic power to unfold and pull proteins against physical forces, which make up a protein's structure and hold it in place. From the many cellular processes, Cdc48 is involved in, its function in endoplasmic reticulum associated protein degradation (ERAD) is understood best. This quality control process for proteins of the secretory pathway scans protein folding and discovers misfolded proteins in the endoplasmic reticulum (ER), the organelle, destined for folding of these proteins and their further delivery to their site of action. Misfolded lumenal and membrane proteins of the ER are detected by chaperones and lectins and retro-translocated out of the ER for degradation. Here the Cdc48 machinery, recruited to the ER membrane, takes over. After polyubiquitylation of the protein substrate, Cdc48 together with its dimeric co-factor complex Ufd1-Npl4 pulls the misfolded protein out and away from the ER membrane and delivers it to down-stream components for degradation by a cytosolic proteinase machine, the proteasome. The known details of the Cdc48-Ufd1-Npl4 motor complex triggered process are subject of this review article. PMID:21945179

  16. Ricin A chain reaches the endoplasmic reticulum after endocytosis

    SciTech Connect

    Liu Qiong; Zhan Jinbiao . E-mail: jzhan2k@zju.edu.cn; Chen Xinhong; Zheng Shu

    2006-05-12

    Ricin is a potent ribosome inactivating protein and now has been widely used for synthesis of immunotoxins. To target ribosome in the mammalian cytosol, ricin must firstly retrograde transport from the endomembrane system to reach the endoplasmic reticulum (ER) where the ricin A chain (RTA) is recognized by ER components that facilitate its membrane translocation to the cytosol. In the study, the fusion gene of enhanced green fluorescent protein (EGFP)-RTA was expressed with the pET-28a (+) system in Escherichia coli under the control of a T7 promoter. The fusion protein showed a green fluorescence. The recombinant protein can be purified by metal chelated affinity chromatography on a column of NTA. The rabbit anti-GFP antibody can recognize the fusion protein of EGFP-RTA just like the EGFP protein. The cytotoxicity of EGFP-RTA and RTA was evaluated by the MTT assay in HeLa and HEP-G2 cells following fluid-phase endocytosis. The fusion protein had a similar cytotoxicity of RTA. After endocytosis, the subcellular location of the fusion protein can be observed with the laser scanning confocal microscopy and the immuno-gold labeling Electro Microscopy. This study provided important evidence by a visualized way to prove that RTA does reach the endoplasmic reticulum.

  17. Endoplasmic reticulum calcium pumps and cancer cell differentiation.

    PubMed

    Papp, Béla; Brouland, Jean-Philippe; Arbabian, Atousa; Gélébart, Pascal; Kovács, Tünde; Bobe, Régis; Enouf, Jocelyne; Varin-Blank, Nadine; Apáti, Agota

    2012-03-05

    The endoplasmic reticulum (ER) is a major intracellular calcium storage pool and a multifunctional organelle that accomplishes several calcium-dependent functions involved in many homeostatic and signaling mechanisms. Calcium is accumulated in the ER by Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA)-type calcium pumps. SERCA activity can determine ER calcium content available for intra-ER functions and for calcium release into the cytosol, and can shape the spatiotemporal characteristics of calcium signals. SERCA function therefore constitutes an important nodal point in the regulation of cellular calcium homeostasis and signaling, and can exert important effects on cell growth, differentiation and survival. In several cell types such as cells of hematopoietic origin, mammary, gastric and colonic epithelium, SERCA2 and SERCA3-type calcium pumps are simultaneously expressed, and SERCA3 expression levels undergo significant changes during cell differentiation, activation or immortalization. In addition, SERCA3 expression is decreased or lost in several tumor types when compared to the corresponding normal tissue. These observations indicate that ER calcium homeostasis is remodeled during cell differentiation, and may present defects due to decreased SERCA3 expression in tumors. Modulation of the state of differentiation of the ER reflected by SERCA3 expression constitutes an interesting new aspect of cell differentiation and tumor biology.

  18. Mitochondria and endoplasmic reticulum crosstalk in amyotrophic lateral sclerosis.

    PubMed

    Manfredi, Giovanni; Kawamata, Hibiki

    2016-06-01

    Physical and functional interactions between mitochondria and the endoplasmic reticulum (ER) are crucial for cell life. These two organelles are intimately connected and collaborate to essential processes, such as calcium homeostasis and phospholipid biosynthesis. The connections between mitochondria and endoplasmic reticulum occur through structures named mitochondria associated membranes (MAMs), which contain lipid rafts and a large number of proteins, many of which serve multiple functions at different cellular sites. Growing evidence strongly suggests that alterations of ER-mitochondria interactions are involved in neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS), a devastating and rapidly fatal motor neuron disease. Mutations in proteins that participate in ER-mitochondria interactions and MAM functions are increasingly being associated with genetic forms of ALS and other neurodegenerative diseases. This evidence strongly suggests that, rather than considering the two organelles separately, a better understanding of the disease process can derive from studying the alterations in their crosstalk. In this review we discuss normal and pathological ER-mitochondria interactions and the evidence that link them to ALS.

  19. Molecular Characterization of Endoplasmic Reticulum Oxidoreductin 1 from Bombyx mori.

    PubMed

    Seo, Minchul; Ryou, Hee-Joo; Yun, Eun-Young; Goo, Tae-Won

    2015-01-01

    We isolated a complementary DNA (cDNA) clone encoding endoplasmic reticulum oxidoreductin 1 (bERO1, a specific oxidant of protein disulfide isomerase (PDI)) from Bombyx mori. This protein has a putative open reading frame (ORF) of 489 amino acids and a predicted size of 57.4 kDa. Although bERO1 protein shares less than 57% amino acid sequence homology with other reported ERO1s, it contains two conserved redox active motifs, a Cys-X-X-X-X-Cys motif of N-terminal and Cys-X-X-Cys-X-X-Cys motif of C-terminal. Both motifs are typically present in ERO1 protein family members. The bEro1 mRNA expression was highest in posterior silk gland on the sixth day of the 5th instar larvae. Expression of bEro1 mRNA also markedly increased during endoplasmic reticulum (ER) stress induced by stimulation with antimycin, calcium ionophore A23187, dithiothreitol, H₂O₂, monencin, and tunicamycin. In addition, expression levels of bEro1 exactly coincided with that of bPdi. This is the first result suggesting that bERO1 plays an essential role in ER quality control through the combined activities of bERO1 and bPDI as a catalyst of protein folding in the ER and sustaining cellular redox homeostasis. PMID:26556347

  20. Smoothing and the second law

    NASA Technical Reports Server (NTRS)

    Merriam, Marshal L.

    1987-01-01

    The technique of obtaining second-order oscillation-free total -variation-diminishing (TVD), scalar difference schemes by adding a limited diffusive flux ('smoothing') to a second-order centered scheme is explored. It is shown that such schemes do not always converge to the correct physical answer. The approach presented here is to construct schemes that numerically satisfy the second law of thermodynamics on a cell-by-cell basis. Such schemes can only converge to the correct physical solution and in some cases can be shown to be TVD. An explicit scheme with this property and second-order spatial accuracy was found to have extremely restrictive time-step limitation. Switching to an implicit scheme removed the time-step limitation.

  1. Smoothing and the second law

    NASA Technical Reports Server (NTRS)

    Merriam, Marshal L.

    1986-01-01

    The technique of obtaining second order, oscillation free, total variation diminishing (TVD), scalar difference schemes by adding a limited diffusion flux (smoothing) to a second order centered scheme is explored. It is shown that such schemes do not always converge to the correct physical answer. The approach presented here is to construct schemes that numerically satisfy the second law of thermodynamics on a cell by cell basis. Such schemes can only converge to the correct physical solution and in some cases can be shown to be TVD. An explicit scheme with this property and second order spatial accuracy was found to have an extremely restrictive time step limitation (Delta t less than Delta x squared). Switching to an implicit scheme removed the time step limitation.

  2. AMPK Dilates Resistance Arteries via Activation of SERCA and BKCa Channels in Smooth Muscle.

    PubMed

    Schneider, Holger; Schubert, Kai Michael; Blodow, Stephanie; Kreutz, Claus-Peter; Erdogmus, Serap; Wiedenmann, Margarethe; Qiu, Jiehua; Fey, Theres; Ruth, Peter; Lubomirov, Lubomir T; Pfitzer, Gabriele; Mederos Y Schnitzler, Michael; Hardie, D Grahame; Gudermann, Thomas; Pohl, Ulrich

    2015-07-01

    The protective effects of 5'-AMP-activated protein kinase (AMPK) on the metabolic syndrome may include direct effects on resistance artery vasomotor function. However, the precise actions of AMPK on microvessels and their potential interaction are largely unknown. Thus, we set to determine the effects of AMPK activation on vascular smooth muscle tone and the underlying mechanisms. Resistance arteries isolated from hamster and mouse exhibited a pronounced endothelium-independent dilation on direct pharmacological AMPK activation by 2 structurally unrelated compounds (PT1 and A769662). The dilation was associated with a decrease of intracellular-free calcium [Ca(2+)]i in vascular smooth muscle cell. AMPK stimulation induced activation of BKCa channels as assessed by patch clamp studies in freshly isolated hamster vascular smooth muscle cell and confirmed by direct proof of membrane hyperpolarization in intact arteries. The BKCa channel blocker iberiotoxin abolished the hyperpolarization but only partially reduced the dilation and did not affect the decrease of [Ca(2+)]i. By contrast, the sarcoplasmic/endoplasmic Ca(2+)-ATPase (SERCA) inhibitor thapsigargin largely reduced these effects, whereas combined inhibition of SERCA and BKCa channels virtually abolished them. AMPK stimulation significantly increased the phosphorylation of the SERCA modulator phospholamban at the regulatory T17 site. Stimulation of smooth muscle AMPK represents a new, potent vasodilator mechanism in resistance vessels. AMPK directly relaxes vascular smooth muscle cell by a decrease of [Ca(2+)]i. This is achieved by calcium sequestration via SERCA activation, as well as activation of BKCa channels. There is in part a mutual compensation of both calcium-lowering mechanisms. However, SERCA activation which involves an AMPK-dependent phosphorylation of phospholamban is the predominant mechanism in resistance vessels.

  3. Cell death and survival through the endoplasmic reticulum-mitochondrial axis.

    PubMed

    Bravo-Sagua, R; Rodriguez, A E; Kuzmicic, J; Gutierrez, T; Lopez-Crisosto, C; Quiroga, C; Díaz-Elizondo, J; Chiong, M; Gillette, T G; Rothermel, B A; Lavandero, S

    2013-02-01

    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial-associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate.

  4. Cell Death and Survival Through the Endoplasmic Reticulum-Mitochondrial Axis

    PubMed Central

    Bravo-Sagua, R.; Rodriguez, A.E.; Kuzmicic, J.; Gutierrez, T.; Lopez-Crisosto, C.; Quiroga, C.; Díaz-Elizondo, J.; Chiong, M.; Gillette, T.G.; Rothermel, B.A.; Lavandero, S.

    2014-01-01

    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial–associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate. PMID:23228132

  5. Cell death and survival through the endoplasmic reticulum-mitochondrial axis.

    PubMed

    Bravo-Sagua, R; Rodriguez, A E; Kuzmicic, J; Gutierrez, T; Lopez-Crisosto, C; Quiroga, C; Díaz-Elizondo, J; Chiong, M; Gillette, T G; Rothermel, B A; Lavandero, S

    2013-02-01

    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial-associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate. PMID:23228132

  6. An adaptive data-smoothing routine

    NASA Technical Reports Server (NTRS)

    Taylor, Clayborne D.; Nicolas, David P.

    1989-01-01

    An adaptive noise reduction algorithm that can be implemented on a microcomputer is developed. Smoothing polynomials are used where the polynomial coefficients are chosen such that the mean-square-error between the noisy and smoothed data is minimized. This approach is equivalent to the implementation of a low-pass finite impulse response filter. The noise reduction depends on the order of the smoothing polynomial. A whiteness test on the error sequence is incorporated to search for the optimal smoothing. Expansion coefficients may be computed via the fast Fourier transform, and the resulting smoothing process is the equivalent of the implementation of an adaptive ideal low-pass filter. Results are obtained for an analytical signal with added white Gaussian noise. The routine may be applied to any smooth signal with additive random noise.

  7. Effects of 4-hydroxynonenal on vascular endothelial and smooth muscle cell redox signaling and function in health and disease☆

    PubMed Central

    Chapple, Sarah J.; Cheng, Xinghua; Mann, Giovanni E.

    2013-01-01

    4-hydroxynonenal (HNE) is a lipid hydroperoxide end product formed from the oxidation of n-6 polyunsaturated fatty acids. The relative abundance of HNE within the vasculature is dependent not only on the rate of lipid peroxidation and HNE synthesis but also on the removal of HNE adducts by phase II metabolic pathways such as glutathione-S-transferases. Depending on its relative concentration, HNE can induce a range of hormetic effects in vascular endothelial and smooth muscle cells, including kinase activation, proliferation, induction of phase II enzymes and in high doses inactivation of enzymatic processes and apoptosis. HNE also plays an important role in the pathogenesis of vascular diseases such as atherosclerosis, diabetes, neurodegenerative disorders and in utero diseases such as pre-eclampsia. This review examines the known production, metabolism and consequences of HNE synthesis within vascular endothelial and smooth muscle cells, highlighting alterations in mitochondrial and endoplasmic reticulum function and their association with various vascular pathologies. PMID:24024167

  8. Endoplasmic reticulum stress contributes to aortic stiffening via proapoptotic and fibrotic signaling mechanisms.

    PubMed

    Spitler, Kathryn M; Webb, R Clinton

    2014-03-01

    Vascular smooth muscle cell apoptosis and collagen synthesis contribute to aortic stiffening. A cellular signaling mechanism contributing to apoptotic and fibrotic events is endoplasmic reticulum (ER) stress. In this study, we tested the hypothesis that induction of ER stress in a normotensive rat would cause profibrotic and apoptotic signaling, thereby contributing to aortic stiffening. Furthermore, we hypothesized that inhibition of ER stress in an angiotensin II (Ang II) model of hypertension would improve aortic stiffening. Induction of ER stress with tunicamycin in normotensive Sprague-Dawley rats (10 μg/kg per day, osmotic pump, 28 days) caused an increase in systolic blood pressure (mm Hg; 160±5) compared with vehicle-treated (127±3) or tunicamycin-treated rats that were cotreated with ER stress inhibitor 4-phenylbutyric acid (100 mg/kg per day, 28 days, [124±6]). There was an increase in aortic apoptosis (fold; 3.0±0.3), collagen content (1.4±0.1), and fibrosis (2.0±0.1) in the tunicamycin-treated rats compared with vehicle-treated rats. Inhibition of ER stress in male Sprague-Dawley rats given Ang II (60 ng/min, osmotic pump, 28 days) and treated with either tauroursodeoxycholic acid or phenylbutyric acid (100 mg/kg per day, i.p., 28 days) led to a 20 mm Hg decrease in blood pressure with either inhibitor compared with Ang II treatment alone. Aortic apoptosis, increased collagen content, and fibrosis in Ang II-treated rats were attenuated with ER stress inhibition. We conclude that ER stress is a new signaling mechanism that contributes to aortic stiffening via promoting apoptosis and fibrosis.

  9. Nongenomic STAT5-dependent effects on Golgi apparatus and endoplasmic reticulum structure and function.

    PubMed

    Lee, Jason E; Yang, Yang-Ming; Liang, Feng-Xia; Gough, Daniel J; Levy, David E; Sehgal, Pravin B

    2012-03-01

    We report unexpected nongenomic functions of signal transducer and activator of transcription (STAT) 5 species in the cytoplasm aimed at preserving the structure and function of the Golgi apparatus and rough endoplasmic reticulum (ER) in vascular cells. Immunoimaging and green fluorescent protein-tagged-STAT5a protein localization studies showed the constitutive association of nonphosphorylated STAT5a, and to a lesser extent STAT5b, with the Golgi apparatus and of STAT5a with centrosomes in human pulmonary arterial endothelial and smooth muscle cells. Acute knockdown of STAT5a/b species using small interfering RNAs (siRNAs), including in the presence of an mRNA synthesis inhibitor (5,6-dichloro-1-β-d-ribofuranosylbenzimidazole), produced a dramatic phenotype within 1 day, consisting of dilatation and fragmentation of Golgi cisternae, a marked tubule-to-cyst change in the ER, increased accumulation of reticulon-4 (RTN4)/Nogo-B and atlastin-3 (ATL3) at cyst-zone boundaries, cystic separation of the outer and inner nuclear membranes, accompanied by scalloped/lunate distortion of the nucleus, with accumulation of RTN4 on convex sides of distorted nuclei. These cells showed inhibition of vesicular stomatitis virus G protein glycoprotein trafficking, mitochondrial fragmentation, and reduced mitochondrial function. STAT5a/b(-/-) mouse embryo fibroblasts also showed altered ER/Golgi dynamics. RTN4 knockdown using siRNA did not affect development of the cystic phenotype; ATL3 siRNA led to effacement of cyst-zone boundaries. In magnetic-bead cross-immunopanning assays, ATL3 bound both STAT5a and STAT5b. Remarkably, this novel cystic ER/lunate nucleus phenotype was characteristic of vascular cells in arterial lesions of idiopathic pulmonary hypertension, an unrelentingly fatal human disease. These data provide evidence of a STAT-family protein regulating the structure of a cytoplasmic organelle and implicate this mechanism in the pathogenesis of a human disease.

  10. Trimeric intracellular cation channels and sarcoplasmic/endoplasmic reticulum calcium homeostasis.

    PubMed

    Zhou, Xinyu; Lin, Peihui; Yamazaki, Daiju; Park, Ki Ho; Komazaki, Shinji; Chen, S R Wayne; Takeshima, Hiroshi; Ma, Jianjie

    2014-02-14

    Trimeric intracellular cation channels (TRIC) represents a novel class of trimeric intracellular cation channels. Two TRIC isoforms have been identified in both the human and the mouse genomes: TRIC-A, a subtype predominantly expressed in the sarcoplasmic reticulum (SR) of muscle cells, and TRIC-B, a ubiquitous subtype expressed in the endoplasmic reticulum (ER) of all tissues. Genetic ablation of either TRIC-A or TRIC-B leads to compromised K(+) permeation and Ca(2+) release across the SR/ER membrane, supporting the hypothesis that TRIC channels provide a counter balancing K(+) flux that reduces SR/ER membrane depolarization for maintenance of the electrochemical gradient that drives SR/ER Ca(2+) release. TRIC-A and TRIC-B seem to have differential functions in Ca(2+) signaling in excitable and nonexcitable cells. Tric-a(-/-) mice display defective Ca(2+) sparks and spontaneous transient outward currents in arterial smooth muscle and develop hypertension, in addition to skeletal muscle dysfunction. Knockout of TRIC-B results in abnormal IP3 receptor-mediated Ca(2+) release in airway epithelial cells, respiratory defects, and neonatal lethality. Double knockout mice lacking both TRIC-A and TRIC-B show embryonic lethality as a result of cardiac arrest. Such an aggravated lethality indicates that TRIC-A and TRIC-B share complementary physiological functions in Ca(2+) signaling in embryonic cardiomyocytes. Tric-a(-/-) and Tric-b(+/-) mice are viable and susceptible to stress-induced heart failure. Recent evidence suggests that TRIC-A directly modulates the function of the cardiac ryanodine receptor 2 Ca(2+) release channel, which in turn controls store-overload-induced Ca(2+) release from the SR. Thus, the TRIC channels, in addition to providing a countercurrent for SR/ER Ca(2+) release, may also function as accessory proteins that directly modulate the ryanodine receptor/IP3 receptor channel functions.

  11. Melatonin inhibits autophagy and endoplasmic reticulum stress in mice with carbon tetrachloride-induced fibrosis.

    PubMed

    San-Miguel, Beatriz; Crespo, Irene; Sánchez, Diana I; González-Fernández, Bárbara; Ortiz de Urbina, Juan J; Tuñón, María J; González-Gallego, Javier

    2015-09-01

    This study aimed to investigate whether inhibition of autophagy and endoplasmic reticulum (ER stress) associates with the antifibrogenic effect of melatonin in mice treated with carbon tetrachloride (CCl4 ). Mice received CCl4 5 μL/g body wt i.p. twice a week for 4 wk or 6 wk. Melatonin was given at 5 or 10 mg/kg/day i.p, beginning 2 wk after the start of CCl4 administration. Treatment with CCl4 resulted in fibrosis evidenced by the staining of α-smooth muscle actin (α-SMA)-positive cells. CCl4 induced an autophagic response measured as the presence of autophagic vesicles, protein 1 light chain 3 (LC3) staining, conversion of LC3-I to autophagosome-associated LC3-II, changes in expression of beclin-1, UV radiation resistance-associated gene (UVRAG), ubiquitin-like autophagy-related (Atg5), Atg12, Atg16L1, sequestosome 1 (p62/SQSTM1), and lysosome-associated membrane protein (LAMP)-2, and increased phosphorylation of the mammalian target of rapamycin (mTOR). There was an increase in the expression of the ER stress chaperones CCAAT/enhancer-binding protein homologous protein (CHOP), immunoglobulin-heavy-chain-binding protein (BiP/GRP78), and 94-kDa glucose-regulated protein (GRP94), and in the mRNA levels of pancreatic ER kinase (PERK), activating transcription factor 6 (ATF6), ATF4, inositol-requiring enzyme 1 (IRE1), and spliced X-box-binding protein-1 (XBP1). Phospho-IRE1, ATF6, and phospho-PERK protein concentration also increased significantly. Immunohistochemical staining of α-SMA indicated an abrogation of hepatic stellate cells activation by melatonin. Furthermore, treatment with the indole resulted in significant inhibition of the autophagic flux and the unfolded protein response. Findings from this study give new insight into molecular pathways accounting for the protective effect of melatonin in fibrogenesis.

  12. The Role of Nogo and the Mitochondria–Endoplasmic Reticulum Unit in Pulmonary Hypertension

    PubMed Central

    Sutendra, Gopinath; Dromparis, Peter; Wright, Paulette; Bonnet, Sébastien; Haromy, Alois; Hao, Zhengrong; McMurtry, M. Sean; Michalak, Marek; Vance, Jean E.; Sessa, William C.; Michelakis, Evangelos D.

    2013-01-01

    Pulmonary arterial hypertension (PAH) is caused by excessive proliferation of vascular cells, which occlude the lumen of pulmonary arteries (PAs) and lead to right ventricular failure. The cause of the vascular remodeling in PAH remains unknown, and the prognosis of PAH remains poor. Abnormal mitochondria in PAH PA smooth muscle cells (SMCs) suppress mitochondria-dependent apoptosis and contribute to the vascular remodeling. We hypothesized that early endoplasmic reticulum (ER) stress, which is associated with clinical triggers of PAH including hypoxia, bone morphogenetic protein receptor II mutations, and HIV/herpes simplex virus infections, explains the mitochondrial abnormalities and has a causal role in PAH. We showed in SMCs from mice that Nogo-B, a regulator of ER structure, was induced by hypoxia in SMCs of the PAs but not the systemic vasculature through activation of the ER stress–sensitive transcription factor ATF6. Nogo-B induction increased the distance between the ER and mitochondria and decreased ER-to-mitochondria phospholipid transfer and intramitochondrial calcium. In addition, we noted inhibition of calcium-sensitive mitochondrial enzymes, increased mitochondrial membrane potential, decreased mitochondrial reactive oxygen species, and decreased mitochondria-dependent apoptosis. Lack of Nogo-B in PASMCs from Nogo-A/B−/− mice prevented these hypoxia-induced changes in vitro and in vivo, resulting in complete resistance to PAH. Nogo-B in the serum and PAs of PAH patients was also increased. Therefore, triggers of PAH may induce Nogo-B, which disrupts the ER-mitochondria unit and suppresses apoptosis. This could rescue PASMCs from death during ER stress but enable the development of PAH through overproliferation. The disruption of the ER-mitochondria unit may be relevant to other diseases in which Nogo is implicated, such as cancer and neurodegeneration. PMID:21697531

  13. Proteomic analysis of the transitional endoplasmic reticulum in hepatocellular carcinoma: an organelle perspective on cancer.

    PubMed

    Roy, Line; Laboissière, Sylvie; Abdou, Eman; Thibault, Geneviève; Hamel, Nathalie; Taheri, Maryam; Boismenu, Daniel; Lanoix, Joël; Kearney, Robert E; Paiement, Jacques

    2010-09-01

    The transitional endoplasmic reticulum (tER) is composed of both rough and smooth ER membranes and thus participates in functions attributed to both these two subcellular compartments. In this paper we have compared the protein composition of tER isolated from dissected liver tumor nodules of aflatoxin B1-treated rats with that of tER from control liver. Tandem mass spectrometry (MS), peptide counts and immunoblot validation were used to identify and determine the relative expression level of proteins. Inhibitors of apoptosis (i.e. PGRMC1, tripeptidyl peptidase II), proteins involved in ribosome biogenesis (i.e. nucleophosmin, nucleolin), proteins involved in translation (i.e. eEF-2, and subunits of eIF-3), proteins involved in ubiquitin metabolism (i.e. proteasome subunits, USP10) and proteins involved in membrane traffic (i.e. SEC13-like 1, SEC23B, dynactin 1) were found overexpressed in tumor tER. Transcription factors (i.e. Pur-beta, BTF3) and molecular targets for C-Myc and NF-kappa B were observed overexpressed in tER from tumor nodules. Down-regulated proteins included cytochrome P450 proteins and enzymes involved in fatty acid metabolism and in steroid metabolism. Unexpectedly expression of the protein folding machinery (i.e. calreticulin) and proteins of the MHC class I peptide-loading complex did not change. Proteins of unknown function were detected in association with the tER and the novel proteins showing differential expression are potential new tumor markers. In many cases differential expression of proteins in tumor tER was comparable to that of corresponding genes reported in the Oncomine human database. Thus the molecular profile of tumor tER is different and this may confer survival advantage to tumor cells in cancer.

  14. Smooth Crossed Products of Rieffel's Deformations

    NASA Astrophysics Data System (ADS)

    Neshveyev, Sergey

    2014-03-01

    Assume is a Fréchet algebra equipped with a smooth isometric action of a vector group V, and consider Rieffel's deformation of . We construct an explicit isomorphism between the smooth crossed products and . When combined with the Elliott-Natsume-Nest isomorphism, this immediately implies that the periodic cyclic cohomology is invariant under deformation. Specializing to the case of smooth subalgebras of C*-algebras, we also get a simple proof of equivalence of Rieffel's and Kasprzak's approaches to deformation.

  15. Smooth GERBS, orthogonal systems and energy minimization

    SciTech Connect

    Dechevsky, Lubomir T. E-mail: pza@hin.no; Zanaty, Peter E-mail: pza@hin.no

    2013-12-18

    New results are obtained in three mutually related directions of the rapidly developing theory of generalized expo-rational B-splines (GERBS) [7, 6]: closed-form computability of C{sup ∞}-smooth GERBS in terms of elementary and special functions, Hermite interpolation and least-squares best approximation via smooth GERBS, energy minimizing properties of smooth GERBS similar to those of the classical cubic polynomial B-splines.

  16. On a smooth quintic 4-fold

    SciTech Connect

    Cheltsov, I A

    2000-10-31

    The birational geometry of an arbitrary smooth quintic 4-fold is studied using the properties of log pairs. As a result, a new proof of its birational rigidity is given and all birational maps of a smooth quintic 4-fold into fibrations with general fibre of Kodaira dimension zero are described. In the Addendum similar results are obtained for all smooth hypersurfaces of degree n in P{sup n} in the case of n equal to 6, 7, or 8.

  17. Polarization smoothing for the National Ignition Facility

    SciTech Connect

    Rothenberg, J F

    1998-08-13

    Polarization smoothing (PS) is the illumination of the target with two distinct and orthogonally polarized speckle patterns. Since these two polarizations do not interfere, the intensity patterns add incoherently and thus the contrast of the intensity nonuniformity can be reduced by a factor of {radical}2 in addition to any reduction achieved by temporal smoothing techniques. Smoothing by PS is completely effective on an instantaneous basis and is therefore of particular interest for the suppression of laser plasma instabilities, which have a very rapid response time. The various implementations of PS are considered and their impact, in conjunction with temporal smoothing methods, on the spatial spectrum of the target illumination is analyzed.

  18. Functional role of stromal interaction molecule 1 (STIM1) in vascular smooth muscle cells

    SciTech Connect

    Takahashi, Yoichiro; Watanabe, Hiroyuki; Murakami, Manabu; Ono, Kyoichi; Munehisa, Yoshiko; Koyama, Takashi; Nobori, Kiyoshi; Iijima, Toshihiko; Ito, Hiroshi

    2007-10-05

    We investigated the functional role of STIM1, a Ca{sup 2+} sensor in the endoplasmic reticulum (ER) that regulates store-operated Ca{sup 2+} entry (SOCE), in vascular smooth muscle cells (VSMCs). STIM1 was mainly localized at the ER and plasma membrane. The knockdown of STIM1 expression by small interfering (si) RNA drastically decreased SOCE. In contrast, an EF-hand mutant of STIM1, STIM1{sup E87A}, produced a marked increase in SOCE, which was abolished by co-transfection with siRNA to transient receptor potential canonical 1 (TRPC1). In addition, transfection with siRNA against STIM1 suppressed phosphorylation of cAMP-responsive element binding protein (CREB) and cell growth. These results suggest that STIM1 is an essential component of SOCE and that it is involved in VSMC proliferation.

  19. Ultrastructural and immunocytochemical studies of smooth muscle cells in iris arterioles of rats with experimental autoimmune uveoretinitis.

    PubMed

    Wang, J; Essner, E; Shichi, H

    1994-12-01

    In this study, we report on the ultrastructural and immunocytochemical changes that occur in smooth muscle cells of iris arterioles in S-antigen-induced experimental autoimmune uveoretinitis (EAU). The inflammatory phase (8-10 days postimmunization) was marked by infiltration of lymphocytes and polymorphonuclear leukocytes and monocytes in the iris stroma and perivascular tissue. Smooth muscle cells became hypertrophic with an 11.5-fold average increase in cell volume compared with control cells. In some of the cells, there was a marked increase in endoplasmic reticulum, ribosomes, and Golgi elements and a concomitant decrease in myofilaments, similar to that reported previously (Wang et al., Curr. Eye Res. 13, 747-754, 1994). However, the majority of hypertrophic smooth muscle cells showed only a slight increase in these synthetic organelles while retaining large amounts of myofilaments. There was no evidence for the migration or mitosis of the hypertrophic cells. Immunogold (IG) labeling of hypertrophic smooth muscle cells revealed changes in the immunoreactivity of several antigens. Labeling density for type I collagen increased progressively between 8 and 10 days, while that of decorin was slightly increased at 8 days and decreased at 10 days postimmunization. IG labeling for an alpha-actin isoform was significantly increased during the 8-10 day period, while that of beta-actin isoform was decreased. The results suggest that hypertrophic smooth muscle cells do not fully modulate to the kind of synthetic phenotype described in aortic smooth muscle cells. The significance of the transition in immunoreactivity from alpha- to beta-actin isoform is not known although it may reflect an increased synthetic state of muscle cells. The increased immunoreactivity of type I collagen and the changes in decorin, on the other hand, suggest that smooth muscle cells in EAU may be involved in remodeling of the extracellular matrix.

  20. Smooth Passage For The Jetfoil

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The Flying Princess is a Boeing Jetfoil, one of a family of commercial waterjets built by Boeing Marine Systems, a division of The Boeing Company, Seattle, Washington. The new Jetfoil offers a number of advantages over earlier hydrofoils, a major one being a smooth ride in rough waters. NASA technology contributed to jolt-free passenger comfort. Hydrofoils skim the surface at speeds considerably greater than those of conventional ships because there is little friction between hull and water. Hulls are raised above the water by the lift of the foils, which resemble and function like an airplane wing. The foils are attached to the hull by rigid struts, which ordinarily cause a vessel operating in coastal seas to follow the contour of the waves. In wind-whipped waters, this makes for a rough ride. Seeking to increase passenger acceptance, Boeing Marine System engineers looked for ways to improve rough-water ride quality. Langley Research Center conducts continuing ride quality research. Initially, it was aimed at improving aircraft ride; it was later expanded to include all modes of transportation. Research includes studies of vibration, acceleration, temperature, humidity, passenger seats and posture, and the psychological aspects of passenger reaction to vehicle ride. As part of the program, Langley developed instrumentation, ride quality models and methods of data analysis.

  1. Smooth horizons and quantum ripples

    NASA Astrophysics Data System (ADS)

    Golovnev, Alexey

    2015-05-01

    Black holes are unique objects which allow for meaningful theoretical studies of strong gravity and even quantum gravity effects. An infalling and a distant observer would have very different views on the structure of the world. However, a careful analysis has shown that it entails no genuine contradictions for physics, and the paradigm of observer complementarity has been coined. Recently this picture was put into doubt. In particular, it was argued that in old black holes a firewall must form in order to protect the basic principles of quantum mechanics. This AMPS paradox has already been discussed in a vast number of papers with different attitudes and conclusions. Here we want to argue that a possible source of confusion is the neglect of quantum gravity effects. Contrary to widespread perception, it does not necessarily mean that effective field theory is inapplicable in rather smooth neighbourhoods of large black hole horizons. The real offender might be an attempt to consistently use it over the huge distances from the near-horizon zone of old black holes to the early radiation. We give simple estimates to support this viewpoint and show how the Page time and (somewhat more speculative) scrambling time do appear.

  2. Endothelin-1-induced endoplasmic reticulum stress in disease.

    PubMed

    Jain, Arjun

    2013-08-01

    The accumulation of unfolded proteins in the endoplasmic reticulum (ER) represents a cellular stress induced by multiple stimuli and pathologic conditions. Recent evidence implicates endothelin-1 (ET-1) in the induction of placental ER stress in pregnancy disorders. ER stress has previously also been implicated in various other disease states, including neurodegenerative disorders, diabetes, and cardiovascular diseases, as has ET-1 in the pathophysiology of these conditions. However, to date, there has been no investigation of the link between ET-1 and the induction of ER stress in these disease states. Based on recent evidence and mechanistic insight into the role of ET-1 in the induction of placental ER stress, the following review attempts to outline the broader implications of ET-1-induced ER stress, as well as strategies for therapeutic intervention based around ET-1. PMID:23740603

  3. Endoplasmic reticulum aminopeptidases in the pathogenesis of ankylosing spondylitis.

    PubMed

    Kenna, Tony J; Robinson, Philip C; Haroon, Nigil

    2015-09-01

    There has been significant progress in our understanding of the pathogenesis of AS. The advent of genome-wide association studies has increased the known loci associated with AS to more than 40. The endoplasmic reticulum resident aminopeptidases (ERAP) 1 and 2 were identified in this manner and are of particular interest. There appears to be a genetic as well as a functional interaction of ERAP1 and 2 with HLA-B27 based on the known functions of these molecules. Recent studies on the structure, immunological effects and the peptide-trimming properties of ERAP 1 and 2 have helped to provide insight into their pathogenic potential in AS. In this review, we explore the role of ERAP 1 and 2 in the pathogenesis of AS.

  4. An adaptable standard for protein export from the endoplasmic reticulum.

    PubMed

    Wiseman, R Luke; Powers, Evan T; Buxbaum, Joel N; Kelly, Jeffery W; Balch, William E

    2007-11-16

    To provide an integrated view of endoplasmic reticulum (ER) function in protein export, we have described the interdependence of protein folding energetics and the adaptable biology of cellular protein folding and transport through the exocytic pathway. A simplified treatment of the protein homeostasis network and a formalism for how this network of competing pathways interprets protein folding kinetics and thermodynamics provides a framework for understanding cellular protein trafficking. We illustrate how folding and misfolding energetics, in concert with the adjustable biological capacities of the folding, degradation, and export pathways, collectively dictate an adaptable standard for protein export from the ER. A model of folding for export (FoldEx) establishes that no single feature dictates folding and transport efficiency. Instead, a network view provides insight into the basis for cellular diversity, disease origins, and protein homeostasis, and predicts strategies for restoring protein homeostasis in protein-misfolding diseases.

  5. Endoplasmic Reticulum Stress in Skeletal Muscle Homeostasis and Disease

    PubMed Central

    Rayavarapu, Sree; Coley, William

    2013-01-01

    Our appreciation of the role of endoplasmic reticulum(ER) stress pathways in both skeletal muscle homeostasis and the progression of muscle diseases is gaining momentum. This review provides insight into ER stress mechanisms during physiologic and pathological disturbances in skeletal muscle. The role of ER stress in the response to dietary alterations and acute stressors, including its role in autoimmune and genetic muscle disorders, has been described. Recent studies identifying ER stress markers in diseased skeletal muscle are noted. The emerging evidence for ER–mitochondrial interplay in skeletal muscle and its importance during chronic ER stress in activation of both inflammatory and cell death pathways (autophagy, necrosis, and apoptosis) have been discussed. Thus, understanding the ER stress–related molecular pathways underlying physiologic and pathological phenotypes in healthy and diseased skeletal muscle should lead to novel therapeutic targets for muscle disease. PMID:22410828

  6. Sphingolipid Homeostasis in the Endoplasmic Reticulum and Beyond

    PubMed Central

    Breslow, David K.

    2013-01-01

    Sphingolipids are a diverse group of lipids that have essential cellular roles as structural components of membranes and as potent signaling molecules. In recent years, a detailed picture has emerged of the basic biochemistry of sphingolipids—from their initial synthesis in the endoplasmic reticulum (ER), to their elaboration into complex glycosphingolipids, to their turnover and degradation. However, our understanding of how sphingolipid metabolism is regulated in response to metabolic demand and physiologic cues remains incomplete. Here I discuss new insights into the mechanisms that ensure sphingolipid homeostasis, with an emphasis on the ER as a critical regulatory site in sphingolipid metabolism. In particular, Orm family proteins have recently emerged as key ER-localized mediators of sphingolipid homeostasis. A detailed understanding of how cells sense and control sphingolipid production promises to provide key insights into membrane function in health and disease. PMID:23545423

  7. Stacked endoplasmic reticulum sheets are connected by helicoidal membrane motifs

    PubMed Central

    Terasaki, Mark; Shemesh, Tom; Kasthuri, Narayanan; Klemm, Robin W.; Schalek, Richard; Hayworth, Kenneth J.; Hand, Arthur R.; Yankova, Maya; Huber, Greg; Lichtman, Jeff W.; Rapoport, Tom A.; Kozlov, Michael M.

    2013-01-01

    The endoplasmic reticulum (ER) often forms stacked membrane sheets, an arrangement that is likely required to accommodate a maximum of membrane-bound polysomes for secretory protein synthesis. How sheets are stacked is unknown. Here, we used novel staining and automated ultra-thin sectioning electron microscopy methods to analyze stacked ER sheets in neuronal cells and secretory salivary gland cells of mice. Our results show that stacked ER sheets form a continuous membrane system in which the sheets are connected by twisted membrane surfaces with helical edges of left- or right-handedness. The three-dimensional structure of tightly stacked ER sheets resembles a parking garage, in which the different levels are connected by helicoidal ramps. A theoretical model explains the experimental observations and indicates that the structure corresponds to a minimum of elastic energy of sheet edges and surfaces. The structure allows the dense packing of ER sheets in the restricted space of a cell. PMID:23870120

  8. The plant endoplasmic reticulum: a cell-wide web.

    PubMed

    Sparkes, Imogen A; Frigerio, Lorenzo; Tolley, Nicholas; Hawes, Chris

    2009-10-15

    The ER (endoplasmic reticulum) in higher plants forms a pleomorphic web of membrane tubules and small cisternae that pervade the cytoplasm, but in particular form a polygonal network at the cortex of the cell which may be anchored to the plasma membrane. The network is associated with the actin cytoskeleton and demonstrates extensive mobility, which is most likely to be dependent on myosin motors. The ER is characterized by a number of domains which may be associated with specific functions such as protein storage, or with direct interaction with other organelles such as the Golgi apparatus, peroxisomes and plastids. In the present review we discuss the nature of the network, the role of shape-forming molecules such as the recently described reticulon family of proteins and the function of some of the major domains within the ER network.

  9. Thermal smoothing of rough surfaces in vacuo

    NASA Technical Reports Server (NTRS)

    Wahl, G.

    1986-01-01

    The derivation of equations governing the smoothing of rough surfaces, based on Mullins' (1957, 1960, and 1963) theories of thermal grooving and of capillarity-governed solid surface morphology is presented. As an example, the smoothing of a one-dimensional sine-shaped surface is discussed.

  10. contbin: Contour binning and accumulative smoothing

    NASA Astrophysics Data System (ADS)

    Sanders, Jeremy S.

    2016-09-01

    Contbin bins X-ray data using contours on an adaptively smoothed map. The generated bins closely follow the surface brightness, and are ideal where the surface brightness distribution is not smooth, or the spectral properties are expected to follow surface brightness. Color maps can be used instead of surface brightness maps.

  11. Leiomodin and tropomodulin in smooth muscle

    NASA Technical Reports Server (NTRS)

    Conley, C. A.

    2001-01-01

    Evidence is accumulating to suggest that actin filament remodeling is critical for smooth muscle contraction, which implicates actin filament ends as important sites for regulation of contraction. Tropomodulin (Tmod) and smooth muscle leiomodin (SM-Lmod) have been found in many tissues containing smooth muscle by protein immunoblot and immunofluorescence microscopy. Both proteins cofractionate with tropomyosin in the Triton-insoluble cytoskeleton of rabbit stomach smooth muscle and are solubilized by high salt. SM-Lmod binds muscle tropomyosin, a biochemical activity characteristic of Tmod proteins. SM-Lmod staining is present along the length of actin filaments in rat intestinal smooth muscle, while Tmod stains in a punctate pattern distinct from that of actin filaments or the dense body marker alpha-actinin. After smooth muscle is hypercontracted by treatment with 10 mM Ca(2+), both SM-Lmod and Tmod are found near alpha-actinin at the periphery of actin-rich contraction bands. These data suggest that SM-Lmod is a novel component of the smooth muscle actin cytoskeleton and, furthermore, that the pointed ends of actin filaments in smooth muscle may be capped by Tmod in localized clusters.

  12. Lunar Smooth Plains Identification and Classification

    NASA Astrophysics Data System (ADS)

    Boyd, A. K.; Robinson, M. S.; Mahanti, P.; Lawrence, S. J.; Spudis, P.; Jolliff, B. L.

    2012-12-01

    Smooth plains are widespread on the Moon and have diverse origins. The maria comprise the majority of the smooth plains and are volcanic in origin. Highland smooth plains are patchy, and tend to fill large craters and basins; their origins have eluded unambiguous classification. Prior to the Apollo 16 mission, many workers thought that highland plains were volcanic, possibly more silicic than the maria. However, as the Apollo 16 samples are mostly impact breccias, the highland smooth plains were re-interpreted basin impact ejecta, most likely from the Imbrium and possibly Orientale basins. Conversely, some known non-mare volcanic units, such as the Apennine Bench Formation, contain light plains. These interpretations do not rule out alternate origins for a subset of highland smooth plains, including impact melt or volcanic origins (effusive or pyroclastic). We developed an algorithm to identify smooth plains using topographic parameters from the WAC Global Lunar Digital Terrain Model (DTM) (GLD100), sampled at 333 m/pixel. We classify the smooth plains using the Clementine UVVIS FeO map and photometrically corrected Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images. Terrain with slopes less than 2° (1 km baseline) and standard deviation of slope less than 0.75° (1 km x 1 km box, n=9) are defined as smooth plains. Highland smooth plains are distinguished from basaltic smooth plains using the following criteria: LROC WAC 643 nm normalized reflectance > 0.056, LROC WAC 321 nm / 415 nm ratio < 0.74, and Clementine FeO < 12 wt.% (excluding Clementine non-coverage areas). The remaining smooth plains are classified as maria and are subdivided into two classes: LROC WAC 321 nm / 415 nm ratio > 0.77 is termed blue maria and a ratio ≤ 0.77 is termed red maria. The automatic classification was limited to the 87% of the Moon covered by photometrically normalized WAC data (60°S to 60°N). The differences between the maria and highland smooth plains

  13. Autophagy modulates endoplasmic reticulum stress-induced cell death in podocytes: a protective role.

    PubMed

    Cheng, Yu-Chi; Chang, Jer-Ming; Chen, Chien-An; Chen, Hung-Chun

    2015-04-01

    Endoplasmic reticulum stress occurs in a variety of patho-physiological mechanisms and there has been great interest in managing this pathway for the treatment of clinical diseases. Autophagy is closely interconnected with endoplasmic reticulum stress to counteract the possible injurious effects related with the impairment of protein folding. Studies have shown that glomerular podocytes exhibit high rate of autophagy to maintain as terminally differentiated cells. In this study, podocytes were exposed to tunicamycin and thapsigargin to induce endoplasmic reticulum stress. Thapsigargin/tunicamycin treatment induced a significant increase in endoplasmic reticulum stress and of cell death, represented by higher GADD153 and GRP78 expression and propidium iodide flow cytometry, respectively. However, thapsigargin/tunicamycin stimulation also enhanced autophagy development, demonstrated by monodansylcadaverine assay and LC3 conversion. To evaluate the regulatory effects of autophagy on endoplasmic reticulum stress-induced cell death, rapamycin (Rap) or 3-methyladenine (3-MA) was added to enhance or inhibit autophagosome formation. Endoplasmic reticulum stress-induced cell death was decreased at 6 h, but was not reduced at 24 h after Rap+TG or Rap+TM treatment. In contrast, endoplasmic reticulum stress-induced cell death increased at 6 and 24 h after 3-MA+TG or 3-MA+TM treatment. Our study demonstrated that thapsigargin/tunicamycin treatment induced endoplasmic reticulum stress which resulted in podocytes death. Autophagy, which counteracted the induced endoplasmic reticulum stress, was simultaneously enhanced. The salvational role of autophagy was supported by adding Rap/3-MA to mechanistically regulate the expression of autophagy and autophagosome formation. In summary, autophagy helps the podocytes from cell death and may contribute to sustain the longevity as a highly differentiated cell lineage.

  14. Autophagy modulates endoplasmic reticulum stress-induced cell death in podocytes: A protective role

    PubMed Central

    Cheng, Yu-Chi; Chang, Jer-Ming; Chen, Chien-An

    2015-01-01

    Endoplasmic reticulum stress occurs in a variety of patho-physiological mechanisms and there has been great interest in managing this pathway for the treatment of clinical diseases. Autophagy is closely interconnected with endoplasmic reticulum stress to counteract the possible injurious effects related with the impairment of protein folding. Studies have shown that glomerular podocytes exhibit high rate of autophagy to maintain as terminally differentiated cells. In this study, podocytes were exposed to tunicamycin and thapsigargin to induce endoplasmic reticulum stress. Thapsigargin/tunicamycin treatment induced a significant increase in endoplasmic reticulum stress and of cell death, represented by higher GADD153 and GRP78 expression and propidium iodide flow cytometry, respectively. However, thapsigargin/tunicamycin stimulation also enhanced autophagy development, demonstrated by monodansylcadaverine assay and LC3 conversion. To evaluate the regulatory effects of autophagy on endoplasmic reticulum stress-induced cell death, rapamycin (Rap) or 3-methyladenine (3-MA) was added to enhance or inhibit autophagosome formation. Endoplasmic reticulum stress-induced cell death was decreased at 6 h, but was not reduced at 24 h after Rap+TG or Rap+TM treatment. In contrast, endoplasmic reticulum stress-induced cell death increased at 6 and 24 h after 3-MA+TG or 3-MA+TM treatment. Our study demonstrated that thapsigargin/tunicamycin treatment induced endoplasmic reticulum stress which resulted in podocytes death. Autophagy, which counteracted the induced endoplasmic reticulum stress, was simultaneously enhanced. The salvational role of autophagy was supported by adding Rap/3-MA to mechanistically regulate the expression of autophagy and autophagosome formation. In summary, autophagy helps the podocytes from cell death and may contribute to sustain the longevity as a highly differentiated cell lineage. PMID:25322957

  15. Urethane and contraction of vascular smooth muscle.

    PubMed Central

    Altura, B. M.; Weinberg, J.

    1979-01-01

    1 In vitro studies were undertaken on rat aortic strips and portal vein segments in order to determine whether or not the anaesthetic, urethane, can exert direct actions on vascular smooth muscle. 2 Urethane was found to inhibit development of spontaneous mechanical activity. This action took place with a urethane concentration as little as one tenth of that found in anaesthetic plasma concentratios, i.e., 10(-3) M. 3 Urethane (10(-3 to 10(-1) M) dose-dependently attenuated contractions induced by adrenaline, angiotensin and KCl. These inhibitory actions were observed with urethane added either before or after the induced contractions. 4 Ca2+-induced contractions of K+-depolarized aortae and portal veins were also attenuated, dose-dependently, by urethane. 5 All of these inhibitory effects were completely, and almost immediately, reversed upon washing out the anaesthetic from the organ baths. 6 A variety of pharmacological antagonists failed to mimic or affect the inhibitory effects induced by urethane. 7 These data suggest that plasma concentrations of urethane commonly associated with induction of surgical anaesthesia can induce, directly, relaxation of vascular muscle. PMID:497529

  16. Nox regulation of smooth muscle contraction.

    PubMed

    Ritsick, Darren R; Edens, William A; Finnerty, Victoria; Lambeth, J David

    2007-07-01

    The catalytic subunit gp91phox (Nox2) of the NADPH oxidase of mammalian phagocytes is activated by microbes and immune mediators to produce large amounts of reactive oxygen species (ROS) which participate in microbial killing. Homologs of gp91phox, the Nox and Duox enzymes, were recently described in a range of organisms, including plants, vertebrates, and invertebrates such as Drosophila melanogaster. While their enzymology and cell biology are being extensively studied in many laboratories, little is known about in vivo functions of Noxes. Here, we establish and use an inducible system for RNAi to discover functions of dNox, an ortholog of human Nox5 in Drosophila. We report here that depletion of dNox in musculature causes retention of mature eggs within ovaries, leading to female sterility. In dNox-depleted ovaries and ovaries treated with a Nox inhibitor, muscular contractions induced by the neuropeptide proctolin are markedly inhibited. This functional defect results from a requirement for dNox-for the proctolin-induced calcium flux in Drosophila ovaries. Thus, these studies demonstrate a novel biological role for Nox-generated ROS in mediating agonist-induced calcium flux and smooth muscle contraction.

  17. SMACK - SMOOTHING FOR AIRCRAFT KINEMATICS

    NASA Technical Reports Server (NTRS)

    Bach, R.

    1994-01-01

    The computer program SMACK (SMoothing for AirCraft Kinematics) is designed to provide flightpath reconstruction of aircraft forces and motions from measurements that are noisy or incomplete. Additionally, SMACK provides a check on instrument accuracy and data consistency. The program can be used to analyze data from flight-test experiments prior to their use in performance, stability and control, or aerodynamic modeling calculations. It can also be used in the analysis of aircraft accidents, where the actual forces and motions may have to be determined from a very limited data set. Application of a state-estimation method for flightpath reconstruction is possible because aircraft forces and motions are related by well-known equations of motion. The task of postflight state estimation is known as a nonlinear, fixed-interval smoothing problem. SMACK utilizes a backward-filter, forward-smoother algorithm to solve the problem. The equations of motion are used to produce estimates that are compared with their corresponding measurement time histories. The procedure is iterative, providing improved state estimates until a minimum squared-error measure is achieved. In the SMACK program, the state and measurement models together represent a finite-difference approximation for the six-degree-of-freedom dynamics of a rigid body. The models are used to generate time histories which are likely to be found in a flight-test measurement set. These include onboard variables such as Euler angles, angular rates, and linear accelerations as well as tracking variables such as slant range, bearing, and elevation. Any bias or scale-factor errors associated with the state or measurement models are appended to the state vector and treated as constant but unknown parameters. The SMACK documentation covers the derivation of the solution algorithm, describes the state and measurement models, and presents several application examples that should help the analyst recognize the potential

  18. Spectral characteristics of sign-alternating self-oscillatory endoplasm mobility in a myxomycete plasmodium

    NASA Astrophysics Data System (ADS)

    Avsievich, T. I.; Frolov, S. V.; Proskurin, S. G.

    2016-01-01

    The results of a short time Fourier transform of the time dependences of the self-oscillatory endoplasm velocity in an isolated strand of the Physarum polycephalum plasmodium recorded using a sign-sensitive laser Doppler microscope are described. Unlike the mode recording an absolute velocity, a sign-sensitive mode makes it possible to detect the pairs of equidistant harmonic components in the time dependence spectra of endoplasm movement. The resulting frequency and amplitude values are used to construct a model adequately describing the alternating endoplasm mobility.

  19. TcGPXII, a glutathione-dependent Trypanosoma cruzi peroxidase with substrate specificity restricted to fatty acid and phospholipid hydroperoxides, is localized to the endoplasmic reticulum.

    PubMed Central

    Wilkinson, Shane R; Taylor, Martin C; Touitha, Said; Mauricio, Isabel L; Meyer, David J; Kelly, John M

    2002-01-01

    Until recently, it had been thought that trypanosomes lack glutathione peroxidase activity. Here we report the subcellular localization and biochemical properties of a second glutathione-dependent peroxidase from Trypanosoma cruzi (TcGPXII). TcGPXII is a single-copy gene which encodes a 16 kDa protein that appears to be specifically dependent on glutathione as the source of reducing equivalents. Recombinant TcGPXII was purified and shown to have peroxidase activity towards a narrow substrate range, restricted to hydroperoxides of fatty acids and phospholipids. Analysis of the pathway revealed that TcGPXII activity could be readily saturated by glutathione and that the peroxidase functioned by a Ping Pong mechanism. Enzyme reduction was shown to be the rate-limiting step in this pathway. Using immunofluorescence, TcGPXII was shown to co-localize with a homologue of immunoglobulin heavy-chain binding protein (BiP), a protein restricted to the endoplasmic reticulum and Golgi. As the smooth endoplasmic reticulum is the site of phospholipid and fatty acid biosynthesis, this suggests that TcGPXII may play a specific role in the T. cruzi oxidative defence system by protecting newly synthesized lipids from peroxidation. PMID:12049643

  20. Identification of functionally segregated sarcoplasmic reticulum calcium stores in pulmonary arterial smooth muscle.

    PubMed

    Clark, Jill H; Kinnear, Nicholas P; Kalujnaia, Svetlana; Cramb, Gordon; Fleischer, Sidney; Jeyakumar, Loice H; Wuytack, Frank; Evans, A Mark

    2010-04-30

    In pulmonary arterial smooth muscle, Ca(2+) release from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyRs) may induce constriction and dilation in a manner that is not mutually exclusive. We show here that the targeting of different sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases (SERCA) and RyR subtypes to discrete SR regions explains this paradox. Western blots identified protein bands for SERCA2a and SERCA2b, whereas immunofluorescence labeling of isolated pulmonary arterial smooth muscle cells revealed striking differences in the spatial distribution of SERCA2a and SERCA2b and RyR1, RyR2, and RyR3, respectively. Almost all SERCA2a and RyR3 labeling was restricted to a region within 1.5 microm of the nucleus. In marked contrast, SERCA2b labeling was primarily found within 1.5 microm of the plasma membrane, where labeling for RyR1 was maximal. The majority of labeling for RyR2 lay in between these two regions of the cell. Application of the vasoconstrictor endothelin-1 induced global Ca(2+) waves in pulmonary arterial smooth muscle cells, which were markedly attenuated upon depletion of SR Ca(2+) stores by preincubation of cells with the SERCA inhibitor thapsigargin but remained unaffected after preincubation of cells with a second SERCA antagonist, cyclopiazonic acid. We conclude that functionally segregated SR Ca(2+) stores exist within pulmonary arterial smooth muscle cells. One sits proximal to the plasma membrane, receives Ca(2+) via SERCA2b, and likely releases Ca(2+) via RyR1 to mediate vasodilation. The other is located centrally, receives Ca(2+) via SERCA2a, and likely releases Ca(2+) via RyR3 and RyR2 to initiate vasoconstriction.

  1. GRP94: an HSP90-like protein specialized for protein folding and quality control in the Endoplasmic Reticulum

    PubMed Central

    Marzec, Michal; Eletto, Davide; Argon, Yair

    2011-01-01

    Glucose-regulated protein 94 is the HSP90-like protein in the lumen of the endoplasmic reticulum and therefore it chaperones secreted and membrane proteins. It has essential functions in development and physiology of multicellular organisms, at least in part because of this unique clientele. GRP94 shares many biochemical features with other HSP90 proteins, in particular its domain structure and ATPase activity, but also displays distinct activities, such as calcium binding, necessitates by the conditions in the endoplasmic reticulum. GRP94’s mode of action varies from the general HSP90 theme in the conformational changes induced by nucleotide binding, and in its interactions with co-chaperones, which are very different from known cytosolic co-chaperones. GRP94 is more selective than many of the ER chaperones and the basis for this selectivity remain obscure. Recent development of molecular tools and functional assays has expanded the spectrum of clients that rely on GRP94 activity, but it is still not clear how the chaperone binds them, or what aspect of folding it impacts. These mechanistic questions and the regulation of GRP94 activity by other proteins and by post-translational modification differences pose new questions and present future research avenues. PMID:22079671

  2. Structural basis of molecular recognition of the Leishmania small hydrophilic endoplasmic reticulum-associated protein (SHERP) at membrane surfaces.

    PubMed

    Moore, Benjamin; Miles, Andrew J; Guerra-Giraldez, Cristina; Simpson, Peter; Iwata, Momi; Wallace, B A; Matthews, Stephen J; Smith, Deborah F; Brown, Katherine A

    2011-03-18

    The 57-residue small hydrophilic endoplasmic reticulum-associated protein (SHERP) shows highly specific, stage-regulated expression in the non-replicative vector-transmitted stages of the kinetoplastid parasite, Leishmania major, the causative agent of human cutaneous leishmaniasis. Previous studies have demonstrated that SHERP localizes as a peripheral membrane protein on the cytosolic face of the endoplasmic reticulum and on outer mitochondrial membranes, whereas its high copy number suggests a critical function in vivo. However, the absence of defined domains or identifiable orthologues, together with lack of a clear phenotype in transgenic parasites lacking SHERP, has limited functional understanding of this protein. Here, we use a combination of biophysical and biochemical methods to demonstrate that SHERP can be induced to adopt a globular fold in the presence of anionic lipids or SDS. Cross-linking and binding studies suggest that SHERP has the potential to form a complex with the vacuolar type H(+)-ATPase. Taken together, these results suggest that SHERP may function in modulating cellular processes related to membrane organization and/or acidification during vector transmission of infective Leishmania. PMID:21106528

  3. Interaction of Vascular Smooth Muscle Cells Under Low Shear Stress

    NASA Technical Reports Server (NTRS)

    Seidel, Charles L.

    1998-01-01

    The blood vessel wall consists of three cellular layers, an outer adventitial, a middle medial and an inner intimal layer. When the blood vessel forms in the embryo it begins as a tube composed of a single cell type called endothelial cells. Over time, other cells are recruited from the surrounding tissue to form additional layers on the outer surface of the endothelial tube. The cells that are recruited are called mesenchymal cells. Mesenchymal cells are responsible for the production of connective tissue that holds the blood vessel together and for developing into vascular smooth muscle cells that are responsible for regulating the diameter of the vessel (1) and therefore, blood flow. In a fully developed blood vessel, the endothelial cells make- up the majority of cells in the intimal layer while the mesenchymal cells make-up the majority of cells in the medial and adventitial layers. Within the medial layer of a mature vessel, cells are organized into multiple circular layers of alternating bands of connective tissue and cells. The cell layer is composed of a mixture of mesenchymal cells that have not developed into smooth muscle cells and fully developed smooth muscle cells (2). The assembly and organization of complex tissues is directed in part by a signaling system composed of proteins on the cell surface called adhesion molecules. Adhesion molecules enable cells to recognize each other as well as the composition of the connective tissue in which they reside (3). It was hypothesized that the different cell types that compose the vascular wall possess different adhesion molecules that enable them to recognize each other and through this recognition system, form the complex layered organization of the vascular wall. In other words, the layered organization is an intrinsic property of the cells. If this hypothesis is correct then the different cells that make up the vessel wall, when mixed together, should organize themselves into a layered structure

  4. AFSMO/AFSCL- AIRFOIL SMOOTHING AND SCALING

    NASA Technical Reports Server (NTRS)

    Morgan, H. L

    1994-01-01

    Since its early beginnings, NASA has been actively involved in the design and testing of airfoil sections for a wide variety of applications. Recently a set of programs has been developed to smooth and scale arbitrary airfoil coordinates. The smoothing program, AFSMO, utilizes both least-squares polynomial and least-squares cubic-spline techniques to iteratively smooth the second derivatives of the y-axis airfoil coordinates with respect to a transformed x-axis system which unwraps the airfoil and stretches the nose and trailing-edge regions. The corresponding smooth airfoil coordinates are then determined by solving a tridiagonal matrix of simultaneous cubic-spline equations relating the y-axis coordinates and their corresponding second derivatives. The camber and thickness distribution of the smooth airfoil are also computed. The scaling program, AFSCL, may then be used to scale the thickness distribution generated by the smoothing program to a specified maximum thickness. Once the thickness distribution has been scaled, it is combined with the camber distribution to obtain the final scaled airfoil contour. The airfoil smoothing and scaling programs are written in FORTRAN IV for batch execution and have been implemented on a CDC CYBER 170 series computer with a central memory requirement of approximately 70K (octal) of 60 bit words. Both programs generate plotted output via CALCOMP type plotting calls. These programs were developed in 1983.

  5. Numerical Convergence In Smoothed Particle Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Zhu, Qirong; Hernquist, Lars; Li, Yuexing

    2015-02-01

    We study the convergence properties of smoothed particle hydrodynamics (SPH) using numerical tests and simple analytic considerations. Our analysis shows that formal numerical convergence is possible in SPH only in the joint limit N → ∞, h → 0, and Nnb → ∞, where N is the total number of particles, h is the smoothing length, and Nnb is the number of neighbor particles within the smoothing volume used to compute smoothed estimates. Previous work has generally assumed that the conditions N → ∞ and h → 0 are sufficient to achieve convergence, while holding Nnb fixed. We demonstrate that if Nnb is held fixed as the resolution is increased, there will be a residual source of error that does not vanish as N → ∞ and h → 0. Formal numerical convergence in SPH is possible only if Nnb is increased systematically as the resolution is improved. Using analytic arguments, we derive an optimal compromise scaling for Nnb by requiring that this source of error balance that present in the smoothing procedure. For typical choices of the smoothing kernel, we find Nnb vpropN 0.5. This means that if SPH is to be used as a numerically convergent method, the required computational cost does not scale with particle number as O(N), but rather as O(N 1 + δ), where δ ≈ 0.5, with a weak dependence on the form of the smoothing kernel.

  6. Small Heat Shock Proteins in Smooth Muscle

    PubMed Central

    Salinthone, Sonemany; Tyagi, Manoj; Gerthoffer, William T.

    2008-01-01

    The small heat shock proteins (HSPs) HSP20, HSP27 and αB-crystallin are chaperone proteins that are abundantly expressed in smooth muscles are important modulators of muscle contraction, cell migration and cell survival. This review focuses on factors regulating expression of small HSPs in smooth muscle, signaling pathways that regulate macromolecular structure and the biochemical and cellular functions of small HSPs. Cellular processes regulated by small HSPs include chaperoning denatured proteins, maintaining cellular redox state and modifying filamentous actin polymerization. These processes influence smooth muscle proliferation, cell migration, cell survival, muscle contraction and synthesis of signaling proteins. Understanding functions of small heat shock proteins is relevant to mechanisms of disease in which dysfunctional smooth muscle causes symptoms, or is a target of drug therapy. One example is that secreted HSP27 may be a useful marker of inflammation during atherogenesis. Another is that phosphorylated HSP20 which relaxes smooth muscle may prove to be highly relevant to treatment of hypertension, vasospasm, asthma, premature labor and overactive bladder. Because small HSPs also modulate smooth muscle proliferation and cell migration they may prove to be targets for developing effective, novel treatments of clinical problems arising from remodeling of smooth muscle in vascular, respiratory and urogenital systems. PMID:18579210

  7. Progress in smooth particle hydrodynamics

    SciTech Connect

    Wingate, C.A.; Dilts, G.A.; Mandell, D.A.; Crotzer, L.A.; Knapp, C.E.

    1998-07-01

    Smooth Particle Hydrodynamics (SPH) is a meshless, Lagrangian numerical method for hydrodynamics calculations where calculational elements are fuzzy particles which move according to the hydrodynamic equations of motion. Each particle carries local values of density, temperature, pressure and other hydrodynamic parameters. A major advantage of SPH is that it is meshless, thus large deformation calculations can be easily done with no connectivity complications. Interface positions are known and there are no problems with advecting quantities through a mesh that typical Eulerian codes have. These underlying SPH features make fracture physics easy and natural and in fact, much of the applications work revolves around simulating fracture. Debris particles from impacts can be easily transported across large voids with SPH. While SPH has considerable promise, there are some problems inherent in the technique that have so far limited its usefulness. The most serious problem is the well known instability in tension leading to particle clumping and numerical fracture. Another problem is that the SPH interpolation is only correct when particles are uniformly spaced a half particle apart leading to incorrect strain rates, accelerations and other quantities for general particle distributions. SPH calculations are also sensitive to particle locations. The standard artificial viscosity treatment in SPH leads to spurious viscosity in shear flows. This paper will demonstrate solutions for these problems that they and others have been developing. The most promising is to replace the SPH interpolant with the moving least squares (MLS) interpolant invented by Lancaster and Salkauskas in 1981. SPH and MLS are closely related with MLS being essentially SPH with corrected particle volumes. When formulated correctly, JLS is conservative, stable in both compression and tension, does not have the SPH boundary problems and is not sensitive to particle placement. The other approach to

  8. Chemical method for producing smooth surfaces on silicon wafers

    DOEpatents

    Yu, Conrad

    2003-01-01

    An improved method for producing optically smooth surfaces in silicon wafers during wet chemical etching involves a pre-treatment rinse of the wafers before etching and a post-etching rinse. The pre-treatment with an organic solvent provides a well-wetted surface that ensures uniform mass transfer during etching, which results in optically smooth surfaces. The post-etching treatment with an acetic acid solution stops the etching instantly, preventing any uneven etching that leads to surface roughness. This method can be used to etch silicon surfaces to a depth of 200 .mu.m or more, while the finished surfaces have a surface roughness of only 15-50 .ANG. (RMS).

  9. Reduction of endoplasmic reticulum stress by 4-phenylbutyric acid prevents the development of hypoxia-induced pulmonary arterial hypertension.

    PubMed

    Koyama, Masayuki; Furuhashi, Masato; Ishimura, Shutaro; Mita, Tomohiro; Fuseya, Takahiro; Okazaki, Yusuke; Yoshida, Hideaki; Tsuchihashi, Kazufumi; Miura, Tetsuji

    2014-05-01

    Pulmonary arterial hypertension (PAH) is characterized by vasoconstriction and vascular remodeling of the pulmonary artery (PA). Recently, endoplasmic reticulum (ER) stress and inappropriate adaptation through the unfolded protein response (UPR) have been disclosed in various types of diseases. Here we examined whether ER stress is involved in the pathogenesis of PAH. Four weeks of chronic normobaric hypoxia increased right ventricular (RV) systolic pressure by 63% compared with that in normoxic controls and induced RV hypertrophy and medial thickening of the PA in C57BL/6J mice. Treatment with 4-phenylbutyric acid (4-PBA), a chemical chaperone, significantly reduced RV systolic pressure by 30%, attenuated RV hypertrophy and PA muscularization, and increased total running distance in a treadmill test by 70% in hypoxic mice. The beneficial effects of 4-PBA were associated with suppressed expression of inflammatory cytokines and ER stress markers, including Grp78 and Grp94 in the activating transcription factor-6 branch, sXbp1 and Pdi in the inositol-requiring enzyme-1 branch and Atf4 in the PKR-like ER kinase branch, and reduced phosphorylation of c-Jun NH2-terminal kinase and eukaryotic translation initiation factor-2α in the lung. The pattern of changes in ER stress and inflammatory markers by 4-PBA in the lung of the PAH model was reproduced in PA smooth muscle cells by chronic stimulation of platelet-derived growth factor-BB or hypoxia. Furthermore, knockdown of each UPR branch sensor activated other branches and promoted proliferation of PA smooth muscle cells. The findings indicate that activation of all branches of the UPR and accompanying inflammation play a major role in the pathogenesis of PAH, and that chemical chaperones are potentially therapeutic agents for PAH.

  10. Subcellular distribution of small GTP binding proteins in pancreas: Identification of small GTP binding proteins in the rough endoplasmic reticulum

    SciTech Connect

    Nigam, S.K. )

    1990-02-01

    Subfractionation of a canine pancreatic homogenate was performed by several differential centrifugation steps, which gave rise to fractions with distinct marker profiles. Specific binding of guanosine 5{prime}-({gamma}-({sup 35}S)thio)triphosphate (GTP({gamma}-{sup 35}S)) was assayed in each fraction. Enrichment of GTP({gamma}-{sup 35}S) binding was greatest in the interfacial smooth microsomal fraction, expected to contain Golgi and other smooth vesicles. There was also marked enrichment in the rough microsomal fraction. Electron microscopy and marker protein analysis revealed the rough microsomes (RMs) to be highly purified rough endoplasmic reticulum (RER). The distribution of small (low molecular weight) GTP binding proteins was examined by a ({alpha}-{sup 32}P)GTP blot-overlay assay. Several apparent GTP binding proteins of molecular masses 22-25 kDa were detected in various subcellular fractions. In particular, at least two such proteins were found in the Golgi-enriched and RM fractions, suggesting that these small GTP binding proteins were localized to the Golgi and RER. To more precisely localize these proteins to the RER, native RMs and RMs stripped of ribosomes by puromycin/high salt were subjected to isopycnic centrifugation. The total GTP({gamma}-{sup 35}S) binding, as well as the small GTP binding proteins detected by the ({alpha}-{sup 32}P)GTP blot overlay, distributed into fractions of high sucrose density, as did the RER marker ribophorin I. Consistent with a RER localization, when the RMS were stripped of ribosomes and subjected to isopycnic centrifugation, the total GTP({gamma}-{sup 35}S) binding and the small GTP binding proteins detected in the blot-overlay assay shifted to fractions of lighter sucrose density along with the RER marker.

  11. PHASE CONTRAST OBSERVATIONS OF THE ENDOPLASMIC RETICULUM IN LIVING TISSUE CULTURES

    PubMed Central

    Rose, George G.; Pomerat, C. M.

    1960-01-01

    Cells from three human sources (two malignant and one fetal) were observed through phase contrast microscopy to contain unusual cytoplasmic images. These were photographed and are discussed as representing the endoplasmic reticulum in the living cell. PMID:13743266

  12. Toll-like receptor 4-induced endoplasmic reticulum stress contributes to endothelial dysfunction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Impairment of vasodilator action of insulin is associated with endothelial dysfunction and insulin resistance. Endoplasmic reticulum (ER) stress is implicated as one of the mechanisms for pathophysiology of various cardiometabolic syndromes, including insulin resistance and endothelial dysfunction. ...

  13. Placental endoplasmic reticulum stress and acidosis: relevant aspects in gestational diabetes.

    PubMed

    Jawerbaum, Alicia

    2016-10-01

    In this issue, Yung and colleagues (doi: 10.1007/s00125-016-4040-2 ) report endoplasmic reticulum stress in the placenta of patients with gestational diabetes mellitus. With the use of a trophoblast-like cell line, these authors identify putative mechanisms involved in, and treatments to prevent the induction of endoplasmic reticulum stress. Here, the relevance and possible implications of these findings and areas for further research are discussed. PMID:27379669

  14. Membrane protein insertion into the endoplasmic reticulum--another channel tunnel?

    PubMed

    High, S

    1992-08-01

    The synthesis of biological membranes requires the insertion of proteins into a lipid bilayer. The rough endoplasmic reticulum of eukaryotic cells is a principal site of membrane biogenesis. The insertion of proteins into the membrane of the endoplasmic reticulum is mediated by a resident proteinaceous machinery. Over the last five years several different experimental approaches have provided information about the components of the machinery and how it may function.

  15. Placental endoplasmic reticulum stress and acidosis: relevant aspects in gestational diabetes.

    PubMed

    Jawerbaum, Alicia

    2016-10-01

    In this issue, Yung and colleagues (doi: 10.1007/s00125-016-4040-2 ) report endoplasmic reticulum stress in the placenta of patients with gestational diabetes mellitus. With the use of a trophoblast-like cell line, these authors identify putative mechanisms involved in, and treatments to prevent the induction of endoplasmic reticulum stress. Here, the relevance and possible implications of these findings and areas for further research are discussed.

  16. Activating transcription factor 4 is involved in endoplasmic reticulum stress-mediated apoptosis contributing to vascular calcification.

    PubMed

    Duan, Xiao-Hui; Chang, Jin-Rui; Zhang, Jing; Zhang, Bao-Hong; Li, Yu-Lin; Teng, Xu; Zhu, Yi; Du, Jie; Tang, Chao-Shu; Qi, Yong-Fen

    2013-09-01

    Our previous work reported that endoplasmic reticulum stress (ERS)-mediated apoptosis was activated during vascular calcification (VC). Activating transcription factor 4 (ATF4) is a critical transcription factor in osteoblastogenesis and ERS-induced apoptosis. However, whether ATF4 is involved in ERS-mediated apoptosis contributing to VC remains unclear. In the present study, in vivo VC was induced in rats by administering vitamin D3 plus nicotine. Vascular smooth muscle cell (VSMC) calcification in vitro was induced by incubation in calcifying media containing β-glycerophosphate and CaCl2. ERS inhibitors taurine or 4-phenylbutyric acid attenuated ERS and VSMC apoptosis in calcified rat arteries, reduced calcification and retarded the VSMC contractile phenotype transforming into an osteoblast-like phenotype in vivo. Inhibition of ERS retarded the VSMC phenotypic transition into an osteoblast-like cell phenotype and reduced VSMC calcification and apoptosis in vitro. Interestingly, ATF4 was activated in calcified aortas and calcified VSMCs in vitro. ATF4 knockdown attenuated ERS-induced apoptosis in calcified VSMCs. ATF4 deficiency blocked VSMC calcification and negatively regulated the osteoblast phenotypic transition of VSMCs in vitro. Our results demonstrate that ATF4 was involved at least in part in the process of ERS-mediated apoptosis contributing to VC.

  17. Mechanical stretch-induced endoplasmic reticulum stress, apoptosis and inflammation contribute to thoracic aortic aneurysm and dissection.

    PubMed

    Jia, Li-Xin; Zhang, Wen-Mei; Zhang, Hong-Jia; Li, Tao-Tao; Wang, Yue-Li; Qin, Yan-Wen; Gu, Hong; Du, Jie

    2015-07-01

    Thoracic aortic aneurysm/dissection (TAAD) is characterized by excessive smooth muscle cell (SMC) loss, extracellular matrix (ECM) degradation and inflammation. In response to certain stimuli, endoplasmic reticulum (ER) stress is activated and regulates apoptosis and inflammation. Excessive apoptosis promotes aortic inflammation and degeneration, leading to TAAD. Therefore, we studied the role of ER stress in TAAD formation. A lysyl oxidase inhibitor, 3-aminopropionitrile fumarate (BAPN), was administrated to induce TAAD formation in mice, which showed significant SMC loss (α-SMA level). Excessive apoptosis (TUNEL staining) and ER stress (ATF4 and CHOP), along with inflammation, were present in TAAD samples from both mouse and human. Transcriptional profiling of SMCs after mechanical stress demonstrated the expression of genes for ER stress and inflammation. To explore the causal role of ER stress in initiating degenerative signalling events and TAAD, we treated wild-type (CHOP(+/+)) or CHOP(-/-) mice with BAPN and found that CHOP deficiency protected against TAAD formation and rupture, as well as reduction in α-SMA level. Both SMC apoptosis and inflammation were significantly reduced in CHOP(-/-) mice. Moreover, SMCs isolated from CHOP(-/-) mice were resistant to mechanical stress-induced apoptosis. Taken together, our results demonstrated that mechanical stress-induced ER stress promotes SMCs apoptosis, inflammation and degeneration, providing insight into TAAD formation and progression.

  18. Oxidized lipids activate autophagy in a JNK-dependent manner by stimulating the endoplasmic reticulum stress response.

    PubMed

    Haberzettl, Petra; Hill, Bradford G

    2013-01-01

    Excessive production of unsaturated aldehydes from oxidized lipoproteins and membrane lipids is a characteristic feature of cardiovascular disease. Our previous studies show that unsaturated lipid peroxidation-derived aldehydes such as 4-hydroxy-trans-2-nonenal (HNE) promote autophagy in rat aortic smooth muscle cells (RASMC). In this study, we examined the mechanism by which HNE induces autophagy. Exposure of RASMC to HNE led to the modification of several proteins, most of which were identified by mass spectrometry and confocal microscopy to be localized to the endoplasmic reticulum (ER). HNE stimulated the phosphorylation of PKR-like ER kinase and eukaryotic initiation factor 2α and increased heme oxygenase-1 (HO-1) abundance. HNE treatment also increased LC3-II formation and the phosphorylation of JNK and p38. Pharmacological inhibition of JNK, but not p38, prevented HNE-induced HO-1 expression and LC3-II formation. Inhibition of JNK increased cell death in HNE-treated cells. Pretreatment with the chemical chaperone phenylbutryic acid prevented LC3-II formation as well as JNK phosphorylation and HO-1 induction. Taken together, these data suggest that autophagic responses triggered by unsaturated aldehydes could be attributed, in part, to ER stress, which stimulates autophagy by a JNK-dependent mechanism and promotes cell survival during oxidative stress.

  19. Chemical chaperon 4-phenylbutyrate protects against the endoplasmic reticulum stress-mediated renal fibrosis in vivo and in vitro.

    PubMed

    Liu, Shing-Hwa; Yang, Ching-Chin; Chan, Ding-Cheng; Wu, Cheng-Tien; Chen, Li-Ping; Huang, Jenq-Wen; Hung, Kuan-Yu; Chiang, Chih-Kang

    2016-04-19

    Renal tubulointerstitial fibrosis is the common and final pathologic change of kidney in end-stage renal disease. Interesting, endoplasmic reticulum (ER) stress is known to contribute to the pathophysiological mechanisms during the development of renal fibrosis. Here, we investigated the effects of chemical chaperon sodium 4-phenylbutyrate (4-PBA) on renal fibrosis in vivo and in vitro. In a rat unilateral ureteral obstruction (UUO) model, 4-PBA mimicked endogenous ER chaperon in the kidneys and significantly reduced glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), activating transcription factor 4 (ATF4), and phosphorylated JNK protein expressions as well as restored spliced X-box-binding protein 1 (XBP1) expressions in the kidneys of UUO rats. 4-PBA also attenuated the increases of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) protein expressions, tubulointerstitial fibrosis, and apoptosis in the kidneys of UUO rats. Moreover, transforming growth factor (TGF)-β markedly increased ER stress-associated molecules, profibrotic factors, and apoptotic markers in the renal tubular cells (NRK-52E), all of which could be significantly counteracted by 4-PBA treatment. 4-PBA also diminished TGF-β-increased CTGF promoter activity and CTGF mRNA expression in NRK-52E cells. Taken together, our results indicated that 4-PBA acts as an ER chaperone to ameliorate ER stress-induced renal tubular cell apoptosis and renal fibrosis.

  20. Chemical chaperon 4-phenylbutyrate protects against the endoplasmic reticulum stress-mediated renal fibrosis in vivo and in vitro.

    PubMed

    Liu, Shing-Hwa; Yang, Ching-Chin; Chan, Ding-Cheng; Wu, Cheng-Tien; Chen, Li-Ping; Huang, Jenq-Wen; Hung, Kuan-Yu; Chiang, Chih-Kang

    2016-04-19

    Renal tubulointerstitial fibrosis is the common and final pathologic change of kidney in end-stage renal disease. Interesting, endoplasmic reticulum (ER) stress is known to contribute to the pathophysiological mechanisms during the development of renal fibrosis. Here, we investigated the effects of chemical chaperon sodium 4-phenylbutyrate (4-PBA) on renal fibrosis in vivo and in vitro. In a rat unilateral ureteral obstruction (UUO) model, 4-PBA mimicked endogenous ER chaperon in the kidneys and significantly reduced glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), activating transcription factor 4 (ATF4), and phosphorylated JNK protein expressions as well as restored spliced X-box-binding protein 1 (XBP1) expressions in the kidneys of UUO rats. 4-PBA also attenuated the increases of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) protein expressions, tubulointerstitial fibrosis, and apoptosis in the kidneys of UUO rats. Moreover, transforming growth factor (TGF)-β markedly increased ER stress-associated molecules, profibrotic factors, and apoptotic markers in the renal tubular cells (NRK-52E), all of which could be significantly counteracted by 4-PBA treatment. 4-PBA also diminished TGF-β-increased CTGF promoter activity and CTGF mRNA expression in NRK-52E cells. Taken together, our results indicated that 4-PBA acts as an ER chaperone to ameliorate ER stress-induced renal tubular cell apoptosis and renal fibrosis. PMID:26959118

  1. Mechanical stretch-induced endoplasmic reticulum stress, apoptosis and inflammation contribute to thoracic aortic aneurysm and dissection.

    PubMed

    Jia, Li-Xin; Zhang, Wen-Mei; Zhang, Hong-Jia; Li, Tao-Tao; Wang, Yue-Li; Qin, Yan-Wen; Gu, Hong; Du, Jie

    2015-07-01

    Thoracic aortic aneurysm/dissection (TAAD) is characterized by excessive smooth muscle cell (SMC) loss, extracellular matrix (ECM) degradation and inflammation. In response to certain stimuli, endoplasmic reticulum (ER) stress is activated and regulates apoptosis and inflammation. Excessive apoptosis promotes aortic inflammation and degeneration, leading to TAAD. Therefore, we studied the role of ER stress in TAAD formation. A lysyl oxidase inhibitor, 3-aminopropionitrile fumarate (BAPN), was administrated to induce TAAD formation in mice, which showed significant SMC loss (α-SMA level). Excessive apoptosis (TUNEL staining) and ER stress (ATF4 and CHOP), along with inflammation, were present in TAAD samples from both mouse and human. Transcriptional profiling of SMCs after mechanical stress demonstrated the expression of genes for ER stress and inflammation. To explore the causal role of ER stress in initiating degenerative signalling events and TAAD, we treated wild-type (CHOP(+/+)) or CHOP(-/-) mice with BAPN and found that CHOP deficiency protected against TAAD formation and rupture, as well as reduction in α-SMA level. Both SMC apoptosis and inflammation were significantly reduced in CHOP(-/-) mice. Moreover, SMCs isolated from CHOP(-/-) mice were resistant to mechanical stress-induced apoptosis. Taken together, our results demonstrated that mechanical stress-induced ER stress promotes SMCs apoptosis, inflammation and degeneration, providing insight into TAAD formation and progression. PMID:25788370

  2. [Cyclic structural changes in endoplasmic reticulum and Golgi apparatus in the hippocampal neurons of ground squirrels during hibernation].

    PubMed

    Bocharova, L S; Gordon, R Ia; Rogachevskiĭ, V V; Ignat'ev, D A; Khutsian, S S

    2011-01-01

    Repetitive remodeling and renewal of the cytoplasmic structures realizing synthesis of proteins accompanies the cycling of ground squirrels between torpor and arousal states during hibernation season. Earlier we have shown partial loss of ribosomes and nucleolus inactivation in CA3 hippocampal pyramidal neurons in each bout of torpor with rapid and full recovery after warming up. Here we describe reversible structural changes in endoplasmic reticulum (ER) and Golgi complex (G) in these neurons. Transformation of ER from mainly cysternal to tubular form and from mainly granular to smooth type occurs at every entrance in torpor, while the opposite change occurs at arousal. Torpor state is also associated with G fragmentation and loss of its flattened cisternae. Appearance in torpor of the autophagosomal vacuoles containing fragments of membrane structures and ribosomes is a sign of their partial destruction. Granular ER restoration, perhaps through assembly from the multilamellar membrane structures, whorls or bags, begins as early as in the middle of the torpor bout, while G flattened cisternae reappear only at warming. ER and G completely restore their structure 2-3 hours after the provoked arousal. Thus, hibernation represents and example of nerve cell structural adaptation to alterations in functional and metabolic activity through both active destruction and renewal of ribosomes, ER, and G. Perhaps, it is the incomplete ER autophagosomal degradation at torpor provides its rapid renewal at arousal by reassembly from the preserved fragments. PMID:21598689

  3. Chemical chaperon 4-phenylbutyrate protects against the endoplasmic reticulum stress-mediated renal fibrosis in vivo and in vitro

    PubMed Central

    Wu, Cheng-Tien; Chen, Li-Ping; Huang, Jenq-Wen; Hung, Kuan-Yu; Chiang, Chih-Kang

    2016-01-01

    Renal tubulointerstitial fibrosis is the common and final pathologic change of kidney in end-stage renal disease. Interesting, endoplasmic reticulum (ER) stress is known to contribute to the pathophysiological mechanisms during the development of renal fibrosis. Here, we investigated the effects of chemical chaperon sodium 4-phenylbutyrate (4-PBA) on renal fibrosis in vivo and in vitro. In a rat unilateral ureteral obstruction (UUO) model, 4-PBA mimicked endogenous ER chaperon in the kidneys and significantly reduced glucose regulated protein 78 (GRP78), CCAAT/enhancer binding protein (C/EBP) homologous protein (CHOP), activating transcription factor 4 (ATF4), and phosphorylated JNK protein expressions as well as restored spliced X-box-binding protein 1 (XBP1) expressions in the kidneys of UUO rats. 4-PBA also attenuated the increases of α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF) protein expressions, tubulointerstitial fibrosis, and apoptosis in the kidneys of UUO rats. Moreover, transforming growth factor (TGF)-β markedly increased ER stress-associated molecules, profibrotic factors, and apoptotic markers in the renal tubular cells (NRK-52E), all of which could be significantly counteracted by 4-PBA treatment. 4-PBA also diminished TGF-β-increased CTGF promoter activity and CTGF mRNA expression in NRK-52E cells. Taken together, our results indicated that 4-PBA acts as an ER chaperone to ameliorate ER stress-induced renal tubular cell apoptosis and renal fibrosis. PMID:26959118

  4. Fluoride-elicited developmental testicular toxicity in rats: Roles of endoplasmic reticulum stress and inflammatory response

    SciTech Connect

    Zhang, Shun; Jiang, Chunyang; Liu, Hongliang; Guan, Zhizhong; Zeng, Qiang; Zhang, Cheng; Lei, Rongrong; Xia, Tao; Gao, Hui; Yang, Lu; Chen, Yihu; Wu, Xue; Zhang, Xiaofei; Cui, Yushan; Yu, Linyu; Wang, Zhenglun; Wang, Aiguo

    2013-09-01

    Long-term excessive fluoride intake is known to be toxic and can damage a variety of organs and tissues in the human body. However, the molecular mechanisms underlying fluoride-induced male reproductive toxicity are not well understood. In this study, we used a rat model to simulate the situations of human exposure and aimed to evaluate the roles of endoplasmic reticulum (ER) stress and inflammatory response in fluoride-induced testicular injury. Sprague–Dawley rats were administered with sodium fluoride (NaF) at 25, 50 and 100 mg/L via drinking water from pre-pregnancy to gestation, birth and finally to post-puberty. And then the testes of male offspring were studied at 8 weeks of age. Our results demonstrated that fluoride treatment increased MDA accumulation, decreased SOD activity, and enhanced germ cell apoptosis. In addition, fluoride elevated mRNA and protein levels of glucose-regulated protein 78 (GRP78), inositol requiring ER-to-nucleus signal kinase 1 (IRE1), and C/EBP homologous protein (CHOP), indicating activation of ER stress signaling. Furthermore, fluoride also induced testicular inflammation, as manifested by gene up-regulation of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), in a nuclear factor-κB (NF-κB)-dependent manner. These were associated with marked histopathological lesions including injury of spermatogonia, decrease of spermatocytes and absence of elongated spermatids, as well as severe ultrastructural abnormalities in testes. Taken together, our results provide compelling evidence that ER stress and inflammation would be novel and significant mechanisms responsible for fluoride-induced disturbance of spermatogenesis and germ cell loss in addition to oxidative stress. - Highlights: • We used a rat model to simulate the situations of human fluoride (F) exposure. • Developmental F exposure induces testicular damage related with oxidative stress.

  5. Backward smoothing for precise GNSS applications

    NASA Astrophysics Data System (ADS)

    Vaclavovic, Pavel; Dousa, Jan

    2015-10-01

    The Extended Kalman filter is widely used for its robustness and simple implementation. Parameters estimated for solving dynamical systems usually require certain time to converge and need to be smoothed by a dedicated algorithms. The purpose of our study was to implement smoothing algorithms for processing both code and carrier phase observations with Precise Point Positioning method. We implemented and used the well known Rauch-Tung-Striebel smoother (RTS). It has been found out that the RTS suffer from significant numerical instability in smoothed state covariance matrix determination. We improved the processing with algorithms based on Singular Value Decomposition, which was more robust. Observations from many permanent stations have been processed with final orbits and clocks provided by the International GNSS service (IGS), and the smoothing improved stability and precision in every cases. Moreover, (re)convergence of the parameters were always successfully eliminated.

  6. Refractory thermal insulation for smooth metal surfaces

    NASA Technical Reports Server (NTRS)

    1964-01-01

    To protect rocket metal surfaces from engine exhaust heat, a refractory thermal insulation mixture, which adheres to smooth metals, has been developed. Insulation protection over a wide temperature range can be controlled by thickness of the applied mixture.

  7. Proline biosynthesis is required for endoplasmic reticulum stress tolerance in Saccharomyces cerevisiae.

    PubMed

    Liang, Xinwen; Dickman, Martin B; Becker, Donald F

    2014-10-01

    The amino acid proline is uniquely involved in cellular processes that underlie stress response in a variety of organisms. Proline is known to minimize protein aggregation, but a detailed study of how proline impacts cell survival during accumulation of misfolded proteins in the endoplasmic reticulum (ER) has not been performed. To address this we examined in Saccharomyces cerevisiae the effect of knocking out the PRO1, PRO2, and PRO3 genes responsible for proline biosynthesis. The null mutants pro1, pro2, and pro3 were shown to have increased sensitivity to ER stress relative to wild-type cells, which could be restored by proline or the corresponding genetic complementation. Of these mutants, pro3 was the most sensitive to tunicamycin and was rescued by anaerobic growth conditions or reduced thiol reagents. The pro3 mutant cells have higher intracellular reactive oxygen species, total glutathione, and a NADP(+)/NADPH ratio than wild-type cells under limiting proline conditions. Depletion of proline biosynthesis also inhibits the unfolded protein response (UPR) indicating proline protection involves the UPR. To more broadly test the role of proline in ER stress, increased proline biosynthesis was shown to partially rescue the ER stress sensitivity of a hog1 null mutant in which the high osmolality pathway is disrupted.

  8. Subcellular localization and rearrangement of endoplasmic reticulum by Brome mosaic virus capsid protein.

    PubMed

    Bamunusinghe, Devinka; Seo, Jang-Kyun; Rao, A L N

    2011-03-01

    Genome packaging in the plant-infecting Brome mosaic virus (BMV), a member of the alphavirus-like superfamily, as well as in other positive-strand RNA viruses pathogenic to humans (e.g., poliovirus) and animals (e.g., Flock House virus), is functionally coupled to replication. Although the subcellular localization site of BMV replication has been identified, that of the capsid protein (CP) has remained elusive. In this study, the application of immunofluorescence confocal microscopy to Nicotiana benthamiana leaves expressing replication-derived BMV CP as a green fluorescent protein (GFP) fusion, in conjunction with antibodies to the CP and double-stranded RNA, a presumed marker of RNA replication, revealed that the subcellular localization sites of replication and CP overlap. Our temporal analysis by transmission electron microscopy of ultrastructural modifications induced in BMV-infected N. benthamiana leaves revealed a reticulovesicular network of modified endoplasmic reticulum (ER) incorporating large assemblies of vesicles derived from ER accumulated in the cytoplasm during BMV infection. Additionally, for the first time, we have found by ectopic expression experiments that BMV CP itself has the intrinsic property of modifying ER to induce vesicles similar to those present in BMV infections. The significance of CP-induced vesicles in relation to CP-organized viral functions that are linked to replication-coupled packaging is discussed.

  9. The endoplasmic reticulum-associated degradation is necessary for plant salt tolerance

    PubMed Central

    Liu, Lijing; Cui, Feng; Li, Qingliang; Yin, Bojiao; Zhang, Huawei; Lin, Baoying; Wu, Yaorong; Xia, Ran; Tang, Sanyuan; Xie, Qi

    2011-01-01

    Eukaryotic organisms have quality-control mechanisms that allow misfolded or unassembled proteins to be retained in the endoplasmic reticulum (ER) and subsequently degraded by ER-associated degradation (ERAD). The ERAD pathway is well studied in yeast and mammals; however, the biological functions of plant ERAD have not been reported. Through molecular and cellular biological approaches, we found that ERAD is necessary for plants to overcome salt stress. Upon salt treatment ubiquitinated proteins increased in plant cells, especially unfolded proteins that quickly accumulated in the ER and subsequently induced ER stress responses. Defect in HRD3A of the HRD1/HRD3 complex of the ERAD pathway resulted in alteration of the unfolded protein response (UPR), increased plant sensitivity to salt, and retention of ERAD substrates in plant cells. Furthermore, we demonstrated that Ca2+ release from the ER is involved in the elevation of UPR and reactive oxygen species (ROS) participates the ERAD-related plant salt response pathway. PMID:21187857

  10. Endoplasmic Reticulum Stress is a Mediator of Post-Transplant Injury in Severely Steatotic Liver Allografts

    PubMed Central

    Anderson, Christopher D.; Upadhya, Gundumi; Conzen, Kendra D.; Jia, Jianlou; Brunt, Elizabeth M.; Tiriveedhi, Venkataswarup; Xie, Yan; Ramachandran, Sabarinathan; Mohanakumar, Thalachallour; Davidson, Nicholas O.; Chapman, William C.

    2010-01-01

    Hepatic steatosis continues to present a major challenge in liver transplantation. These organs have been shown to have an increased susceptibility to cold ischemia and reperfusion (CIR) injury compared to otherwise comparable lean livers; the mechanisms governing this increased susceptibility to CIR injury are not fully understood. Endoplasmic reticulum (ER) stress is an important link between hepatic steatosis, insulin resistance and the metabolic syndrome. In this study, we investigated ER stress signaling and blockade in the mediation of CIR injury in severely steatotic rodent allografts. Steatotic allografts from genetically leptin-resistant rodents had increased ER stress responses and increased markers of hepatocellular injury following liver transplantation into strain-matched lean recipients. ER stress response components were decreased by the chemical chaperone, TUDCA, resulting in improvement of the allograft injury. TUDCA treatment decreased NF-κB activation, and the pro-inflammatory cytokines IL-6 and IL-1β. However, the predominant response was decreased expression of the ER stress cell death mediator, CHOP. Further, activation of the inflammation-associated caspase 11 was decreased linking ER Stress/CHOP to pro-inflammatory cytokine production following steatotic liver transplantation. These data confirm ER stress in steatotic allografts, and implicate this as a mediating mechanism of inflammation and hepatocyte death in the steatotic liver allograft. PMID:21280192

  11. Inhibition of TFG function causes hereditary axon degeneration by impairing endoplasmic reticulum structure

    PubMed Central

    Beetz, Christian; Johnson, Adam; Schuh, Amber L.; Thakur, Seema; Varga, Rita-Eva; Fothergill, Thomas; Hertel, Nicole; Bomba-Warczak, Ewa; Thiele, Holger; Nürnberg, Gudrun; Altmüller, Janine; Saxena, Renu; Chapman, Edwin R.; Dent, Erik W.; Nürnberg, Peter; Audhya, Anjon

    2013-01-01

    Hereditary spastic paraplegias are a clinically and genetically heterogeneous group of gait disorders. Their pathological hallmark is a length-dependent distal axonopathy of nerve fibers in the corticospinal tract. Involvement of other neurons can cause additional neurological symptoms, which define a diverse set of complex hereditary spastic paraplegias. We present two siblings who have the unusual combination of early-onset spastic paraplegia, optic atrophy, and neuropathy. Genome-wide SNP-typing, linkage analysis, and exome sequencing revealed a homozygous c.316C>T (p.R106C) variant in the Trk-fused gene (TFG) as the only plausible mutation. Biochemical characterization of the mutant protein demonstrated a defect in its ability to self-assemble into an oligomeric complex, which is critical for normal TFG function. In cell lines, TFG inhibition slows protein secretion from the endoplasmic reticulum (ER) and alters ER morphology, disrupting organization of peripheral ER tubules and causing collapse of the ER network onto the underlying microtubule cytoskeleton. The present study provides a unique link between altered ER architecture and neurodegeneration. PMID:23479643

  12. Cadmium impairs protein folding in the endoplasmic reticulum and induces the unfolded protein response.

    PubMed

    Le, Quynh Giang; Ishiwata-Kimata, Yuki; Kohno, Kenji; Kimata, Yukio

    2016-08-01

    Cellular exposure to cadmium is known to strongly induce the unfolded protein response (UPR), which suggests that the endoplasmic reticulum (ER) is preferentially damaged by cadmium. According to recent reports, the UPR is induced both dependent on and independently of accumulation of unfolded proteins in the ER. In order to understand the toxic mechanism of cadmium, here we investigated how cadmium exposure leads to Ire1 activation, which triggers the UPR, using yeast Saccharomyces cerevisiae as a model organism. Cadmium poorly induced the UPR when Ire1 carried a mutation that impairs its ability to recognize unfolded proteins. Ire1 activation by cadmium was also attenuated by the chemical chaperone 4-phenylbutyrate. Cadmium caused sedimentation of BiP, the molecular chaperone in the ER, which suggests the ER accumulation of unfolded proteins. A green fluorescent protein-based reporter assay also indicated that cadmium damages the oxidative protein folding in the ER. We also found that an excess concentration of extracellular calcium attenuates the Ire1 activation by cadmium. Taken together, we propose that cadmium exposure leads to the UPR induction through impairment of protein folding in the ER. PMID:27298227

  13. Determinant for endoplasmic reticulum retention in the luminal domain of the human cytomegalovirus US3 glycoprotein.

    PubMed

    Lee, Sungwook; Park, Boyoun; Ahn, Kwangseog

    2003-02-01

    US3 of human cytomegalovirus is an endoplasmic reticulum resident transmembrane glycoprotein that binds to major histocompatibility complex class I molecules and prevents their departure. The endoplasmic reticulum retention signal of the US3 protein is contained in the luminal domain of the protein. To define the endoplasmic reticulum retention sequence in more detail, we have generated a series of deletion and point mutants of the US3 protein. By analyzing the rate of intracellular transport and immunolocalization of the mutants, we have identified Ser58, Glu63, and Lys64 as crucial for retention, suggesting that the retention signal of the US3 protein has a complex spatial arrangement and does not comprise a contiguous sequence of amino acids. We also show that a modified US3 protein with a mutation in any of these amino acids maintains its ability to bind class I molecules; however, such mutated proteins are no longer retained in the endoplasmic reticulum and are not able to block the cell surface expression of class I molecules. These findings indicate that the properties that allow the US3 glycoprotein to be localized in the endoplasmic reticulum and bind major histocompatibility complex class I molecules are located in different parts of the molecule and that the ability of US3 to block antigen presentation is due solely to its ability to retain class I molecules in the endoplasmic reticulum. PMID:12525649

  14. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    PubMed

    Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774

  15. Smooth muscle-like tissue constructs with circumferentially oriented cells formed by the cell fiber technology.

    PubMed

    Hsiao, Amy Y; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments.

  16. Smooth Muscle-Like Tissue Constructs with Circumferentially Oriented Cells Formed by the Cell Fiber Technology

    PubMed Central

    Hsiao, Amy Y.; Okitsu, Teru; Onoe, Hiroaki; Kiyosawa, Mahiro; Teramae, Hiroki; Iwanaga, Shintaroh; Kazama, Tomohiko; Matsumoto, Taro; Takeuchi, Shoji

    2015-01-01

    The proper functioning of many organs and tissues containing smooth muscles greatly depends on the intricate organization of the smooth muscle cells oriented in appropriate directions. Consequently controlling the cellular orientation in three-dimensional (3D) cellular constructs is an important issue in engineering tissues of smooth muscles. However, the ability to precisely control the cellular orientation at the microscale cannot be achieved by various commonly used 3D tissue engineering building blocks such as spheroids. This paper presents the formation of coiled spring-shaped 3D cellular constructs containing circumferentially oriented smooth muscle-like cells differentiated from dedifferentiated fat (DFAT) cells. By using the cell fiber technology, DFAT cells suspended in a mixture of extracellular proteins possessing an optimized stiffness were encapsulated in the core region of alginate shell microfibers and uniformly aligned to the longitudinal direction. Upon differentiation induction to the smooth muscle lineage, DFAT cell fibers self-assembled to coiled spring structures where the cells became circumferentially oriented. By changing the initial core-shell microfiber diameter, we demonstrated that the spring pitch and diameter could be controlled. 21 days after differentiation induction, the cell fibers contained high percentages of ASMA-positive and calponin-positive cells. Our technology to create these smooth muscle-like spring constructs enabled precise control of cellular alignment and orientation in 3D. These constructs can further serve as tissue engineering building blocks for larger organs and cellular implants used in clinical treatments. PMID:25734774

  17. Lunar Smooth Plains Identification and Classification

    NASA Astrophysics Data System (ADS)

    Boyd, A. K.; Mahanti, P.; Robinson, M. S.; Lawrence, S. J.; Spudis, P. D.; Jolliff, B. L.

    2012-09-01

    Smooth plains are widespread on the Moon and appear to have diverse origins. The maria comprise the majority of the smooth plains on the Moon and are volcanic in origin. Highland smooth plains are patchy and tend to fill large craters and basins; their origins have eluded unambiguous classification. Prior to the Apollo 16 mission, many workers thought that smooth highland plains were volcanic, possibly more silicic than the basaltic maria [e.g., 1]. However, as the Apollo 16 samples are mostly impact breccias, the highland smooth plains were re-interpreted as being deposits generated by impact events, most likely ejecta from the youngest and largest multi-ring basins, e.g., Imbrium and Orientale [1]. Spectral interpretations by Pieters [2] showed that the highland light plains are not mare basalt, but are composed of significantly more feldspathic, nonmare material [2]. Conversely, some known non-mare volcanic units, such as the Apennine Bench Formation (a deposit of post-Imbrium KREEP basalt [3,4]), contain light plains. These interpretations do not rule out alternate origins for a subset of highland smooth plains, including impact melt or volcanic origins (effusive or pyroclastic). We have developed an algorithm to identify smooth plains using topographic parameters from the WAC Global Lunar Digital Terrain Model (DTM) (GLD100) [5], sampled at 333 m/pixel. We classify the identified smooth plains using the Clementine UVVIS FeO map and photometrically corrected Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) images [6]. In this abstract, we do not address formation mechanisms for the nonmare deposits.

  18. Beam-smoothing investigation on Heaven I

    NASA Astrophysics Data System (ADS)

    Xiang, Yi-huai; Gao, Zhi-xing; Tong, Xiao-hui; Dai, Hui; Tang, Xiu-zhang; Shan, Yu-sheng

    2007-01-01

    Directly driven targets for inertial confinement fusion (ICF) require laser beams with extremely smooth irradiance profiles to prevent hydrodynamic instabilities that destroy the spherical symmetry of the target during implosion. Such instabilities can break up and mix together the target's wall and fuel material, preventing it from reaching the density and temperature required for fusion ignition. 1,2 Measurements in the equation of state (EOS) experiments require laser beams with flat-roofed profiles to generate uniform shockwave 3. Some method for beam smooth, is thus needed. A technique called echelon-free induced spatial incoherence (EFISI) is proposed for producing smooth target beam profiles with large KrF lasers. The idea is basically an image projection technique that projects the desired time-averaged spatial profile onto the target via the laser system, using partially coherent broadband lighe. Utilize the technique, we developing beam- smoothing investigation on "Heaven I". At China Institute of Atomic Energy , a new angular multiplexing providing with beam-smoothing function has been developed, the total energy is 158J, the stability of energy is 4%, the pulse duration is 25ns, the effective diameter of focusing spot is 400um, and the ununiformity is about 1.6%, the power density on the target is about 3.7×10 12W/cm2. At present, the system have provided steady and smooth laser irradiation for EOS experiments.

  19. Role of endoplasmic reticulum stress in drug-induced toxicity.

    PubMed

    Foufelle, Fabienne; Fromenty, Bernard

    2016-02-01

    Drug-induced toxicity is a key issue for public health because some side effects can be severe and life-threatening. These adverse effects can also be a major concern for the pharmaceutical companies since significant toxicity can lead to the interruption of clinical trials, or the withdrawal of the incriminated drugs from the market. Recent studies suggested that endoplasmic reticulum (ER) stress could be an important event involved in drug liability, in addition to other key mechanisms such as mitochondrial dysfunction and oxidative stress. Indeed, drug-induced ER stress could lead to several deleterious effects within cells and tissues including accumulation of lipids, cell death, cytolysis, and inflammation. After recalling important information regarding drug-induced adverse reactions and ER stress in diverse pathophysiological situations, this review summarizes the main data pertaining to drug-induced ER stress and its potential involvement in different adverse effects. Drugs presented in this review are for instance acetaminophen (APAP), arsenic trioxide and other anticancer drugs, diclofenac, and different antiretroviral compounds. We also included data on tunicamycin (an antibiotic not used in human medicine because of its toxicity) and thapsigargin (a toxic compound of the Mediterranean plant Thapsia garganica) since both molecules are commonly used as prototypical toxins to induce ER stress in cellular and animal models. PMID:26977301

  20. Proper symmetric and asymmetric endoplasmic reticulum partitioning requires astral microtubules

    PubMed Central

    Smyth, Jeremy T.; Schoborg, Todd A.; Bergman, Zane J.; Riggs, Blake; Rusan, Nasser M.

    2015-01-01

    Mechanisms that regulate partitioning of the endoplasmic reticulum (ER) during cell division are largely unknown. Previous studies have mostly addressed ER partitioning in cultured cells, which may not recapitulate physiological processes that are critical in developing, intact tissues. We have addressed this by analysing ER partitioning in asymmetrically dividing stem cells, in which precise segregation of cellular components is essential for proper development and tissue architecture. We show that in Drosophila neural stem cells, called neuroblasts, the ER asymmetrically partitioned to centrosomes early in mitosis. This correlated closely with the asymmetric nucleation of astral microtubules (MTs) by centrosomes, suggesting that astral MT association may be required for ER partitioning by centrosomes. Consistent with this, the ER also associated with astral MTs in meiotic Drosophila spermatocytes and during syncytial embryonic divisions. Disruption of centrosomes in each of these cell types led to improper ER partitioning, demonstrating the critical role for centrosomes and associated astral MTs in this process. Importantly, we show that the ER also associated with astral MTs in cultured human cells, suggesting that this centrosome/astral MT-based partitioning mechanism is conserved across animal species. PMID:26289801

  1. Protein Bodies in Leaves Exchange Contents through the Endoplasmic Reticulum.

    PubMed

    Saberianfar, Reza; Sattarzadeh, Amirali; Joensuu, Jussi J; Kohalmi, Susanne E; Menassa, Rima

    2016-01-01

    Protein bodies (PBs) are organelles found in seeds whose main function is the storage of proteins that are used during germination for sustaining growth. PBs can also be induced to form in leaves when foreign proteins are produced at high levels in the endoplasmic reticulum (ER) and when fused to one of three tags: Zera®, elastin-like polypeptides (ELP), or hydrophobin-I (HFBI). In this study, we investigate the differences between ELP, HFBI and Zera PB formation, packing, and communication. Our results confirm the ER origin of all three fusion-tag-induced PBs. We show that secretory pathway proteins can be sequestered into all types of PBs but with different patterns, and that different fusion tags can target a specific protein to different PBs. Zera PBs are mobile and dependent on actomyosin motility similar to ELP and HFBI PBs. We show in vivo trafficking of proteins between PBs using GFP photoconversion. We also show that protein trafficking between ELP or HFBI PBs is faster and proteins travel further when compared to Zera PBs. Our results indicate that fusion-tag-induced PBs do not represent terminally stored cytosolic organelles, but that they form in, and remain part of the ER, and dynamically communicate with each other via the ER. We hypothesize that the previously documented PB mobility along the actin cytoskeleton is associated with ER movement rather than independent streaming of detached organelles. PMID:27242885

  2. Endoplasmic reticulum stress, diabetes mellitus, and tissue injury.

    PubMed

    Huang, Liu; Xie, Hong; Liu, Hao

    2014-01-01

    Endoplasmic reticulum (ER) stress is characterized by the accumulation of unfolded and misfolded proteins in the ER lumen. Unfolded and misfolded protein accumulation interferes with the ER function and triggers ER stress response. Thus, ER stress response, also called unfolded protein response (UPR), is an adaptive process that controls the protein amount in the ER lumen and the downstream protein demand. In normal conditions, the role of ER stress is to maintain ER homeostasis, restore ER function, and protect stressed cells from apoptosis, by coordinating gene expression, protein synthesis, and accelerating protein degradation through several molecular pathways. However, prolonged ER stress response plays a paradoxical role, which leads to cell damage, apoptosis, and concomitant tissue injuries. A number of tissue alterations are involved with diabetes mellitus progress and its comorbidities via ER stress. However, certain pharmacological agents affecting ER stress have been identified. In this review, we summarized the relationship between ER stress and insulin resistance development. Moreover, we aim to explain how ER stress influences type 2 diabetes mellitus (T2DM) development. In addition, we reviewed the literature on ER stress and UPR in three kinds of tissue injuries induced by T2DM. Finally, a retrospective analysis of the effects of anti-diabetes medications on ER stress is presented.

  3. Naltrexone attenuates endoplasmic reticulum stress induced hepatic injury in mice.

    PubMed

    Moslehi, A; Nabavizadeh, F; Nabavizadeh, Fatemeh; Dehpour, A R; Dehpou, A R; Tavanga, S M; Hassanzadeh, G; Zekri, A; Nahrevanian, H; Sohanaki, H

    2014-09-01

    Endoplasmic reticulum (ER) stress provides abnormalities in insulin action, inflammatory responses, lipoprotein B100 degradation and hepatic lipogenesis. Excess accumulation of triglyceride in hepatocytes may also lead to disorders such as non-alcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH). Opioid peptides are involved in triglyceride and cholesterol dysregulation, inflammation and cell death. In this study, we evaluated Naltrexone effects on ER stress induced liver injury. To do so, C57/BL6 mice received saline, DMSO and Naltrexone, as control groups. ER stress was induced by tunicamycin (TM) injection. Naltrexone was given before TM administration. Liver blood flow and biochemical serum analysis were measured. Histopathological evaluations, TNF-α measurement and Real-time RT-PCR were also performed. TM challenge provokes steatosis, cellular ballooning and lobular inflammation which significantly reduced in Naltrexone treated animals. ALT, AST and TNF-α increased in the TM group and improved in the Naltrexone plus TM group. Triglyceride and cholesterol levels decreased in TM treated mice with no increase in Naltrexone treated animals. In the Naltrexone plus TM group, gene expression of Bax/Bcl-2 ratio and caspase3 significantly lowered compared with the TM group. In this study, we found that Naltrexone had a notable alleviating role in ER stress induced steatosis and liver injury.

  4. Improvement of chemotherapeutic drug efficacy by endoplasmic reticulum stress.

    PubMed

    Mihailidou, Chrysovalantou; Chatzistamou, Ioulia; Papavassiliou, Athanasios G; Kiaris, Hippokratis

    2015-04-01

    Tunicamycin (TUN), an inhibitor of protein glycosylation and therefore a potent stimulator of endoplasmic reticulum (ER) stress, has been used to improve anticancer drug efficacy, but the underlying mechanism remains obscure. In this study, we show that acute administration of TUN in mice induces the unfolded protein response and suppresses the levels of P21, a cell cycle regulator with anti-apoptotic activity. The inhibition of P21 after ER stress appears to be C/EBP homologous protein (CHOP)-dependent because in CHOP-deficient mice, TUN not only failed to suppress, but rather induced the expression of P21. Results of promoter-activity reporter assays using human cancer cells and mouse fibroblasts indicated that the regulation of P21 by CHOP operates at the level of transcription and involves direct binding of CHOP transcription factor to the P21 promoter. The results of cell viability and clonogenic assays indicate that ER-stress-related suppression of P21 expression potentiates caspase activation and sensitizes cells to doxorubicin treatment, while administration of TUN to mice increases the therapeutic efficacy of anticancer therapy for HepG2 liver and A549 lung cancers.

  5. Heme oxygenase-1 comes back to endoplasmic reticulum

    SciTech Connect

    Kim, Hong Pyo; Pae, Hyun-Ock; Back, Sung Hun; Chung, Su Wol; Woo, Je Moon; Son, Yong; Chung, Hun-Taeg

    2011-01-07

    Research highlights: {yields} Although multiple compartmentalization of HO-1 has been documented, the functional implication of this enzyme at these subcellular organelles is only partially elucidated. {yields} HO-1 expression at ER is induced by a diverse set of conditions that cause ER stressors. {yields} CO may induce HO-1 expression in human ECs by activating Nrf2 through PERK phosphorylation in a positive-feedback manner. {yields} ER-residing HO-1 and its cytoprotective activity against ER stress is discussed. -- Abstract: Originally identified as a rate-limiting enzyme for heme catabolism, heme oxygenase-1 (HO-1) has expanded its roles in anti-inflammation, anti-apoptosis and anti-proliferation for the last decade. Regulation of protein activity by location is well appreciated. Even though multiple compartmentalization of HO-1 has been documented, the functional implication of this enzyme at these subcellular organelles is only partially elucidated. In this review we discuss the endoplasmic reticulum (ER)-residing HO-1 and its cytoprotective activity against ER stress.

  6. A Molecular Web: Endoplasmic Reticulum Stress, Inflammation, and Oxidative Stress

    PubMed Central

    Chaudhari, Namrata; Talwar, Priti; Parimisetty, Avinash; Lefebvre d’Hellencourt, Christian; Ravanan, Palaniyandi

    2014-01-01

    Execution of fundamental cellular functions demands regulated protein folding homeostasis. Endoplasmic reticulum (ER) is an active organelle existing to implement this function by folding and modifying secretory and membrane proteins. Loss of protein folding homeostasis is central to various diseases and budding evidences suggest ER stress as being a major contributor in the development or pathology of a diseased state besides other cellular stresses. The trigger for diseases may be diverse but, inflammation and/or ER stress may be basic mechanisms increasing the severity or complicating the condition of the disease. Chronic ER stress and activation of the unfolded-protein response (UPR) through endogenous or exogenous insults may result in impaired calcium and redox homeostasis, oxidative stress via protein overload thereby also influencing vital mitochondrial functions. Calcium released from the ER augments the production of mitochondrial Reactive Oxygen Species (ROS). Toxic accumulation of ROS within ER and mitochondria disturbs fundamental organelle functions. Sustained ER stress is known to potentially elicit inflammatory responses via UPR pathways. Additionally, ROS generated through inflammation or mitochondrial dysfunction could accelerate ER malfunction. Dysfunctional UPR pathways have been associated with a wide range of diseases including several neurodegenerative diseases, stroke, metabolic disorders, cancer, inflammatory disease, diabetes mellitus, cardiovascular disease, and others. In this review, we have discussed the UPR signaling pathways, and networking between ER stress-induced inflammatory pathways, oxidative stress, and mitochondrial signaling events, which further induce or exacerbate ER stress. PMID:25120434

  7. Coordination of Endoplasmic Reticulum (ER) Signaling During Maize Seed Development

    SciTech Connect

    Boston, Rebecca S.

    2010-11-20

    Seed storage reserves represent one of the most important sources of renewable fixed carbon and nitrogen found in nature. Seeds are well-adapted for diverting metabolic resources to synthesize storage proteins as well as enzymes and structural proteins needed for their transport and packaging into membrane bound storage protein bodies. Our underlying hypothesis is that the endoplasmic reticulum (ER) stress response provides the critical cellular control of metabolic flux required for optimal accumulation of storage reserves in seeds. This highly conserved response is a cellular mechanism to monitor the protein folding environment of the ER and restore homeostasis in the presence of unfolded or misfolded proteins. In seeds, deposition of storage proteins in protein bodies is a highly specialized process that takes place even in the presence of mutant proteins that no longer fold and package properly. The capacity of the ER to deposit these aberrant proteins in protein bodies during a period that extends several weeks provides an excellent model for deconvoluting the ER stress response of plants. We have focused in this project on the means by which the ER senses and responds to functional perturbations and the underlying intracellular communication that occurs among biosynthetic, trafficking and degradative pathways for proteins during seed development.

  8. Paclitaxel inhibits selenoprotein S expression and attenuates endoplasmic reticulum stress.

    PubMed

    Qin, Hong-Shuang; Yu, Pei-Pei; Sun, Ying; Wang, Dan-Feng; Deng, Xiao-Fen; Bao, Yong-Li; Song, Jun; Sun, Lu-Guo; Song, Zhen-Bo; Li, Yu-Xin

    2016-06-01

    The primary effect of the endoplasmic reticulum (ER) stress response or unfolded protein response (UPR) is to reduce the load of unfolded protein and promote survival. However, prolonged and severe ER stress leads to tissue injury and serious diseases. Thus, it is important to identify drugs that can attenuate ER stress for the treatment of diseases. Natural products continue to provide lead compounds for drug discovery and front‑line pharmacotherapy for people worldwide. Previous studies have indicated that selenoprotein S (SelS) is a sensitive and ideal maker of ER stress. In the present study, a firefly luciferase reporter driven by the SelS gene promoter was used to screen for natural compounds capable of attenuating ER stress. From this, paclitaxel (PTX) was identified to efficiently inhibit the promoter activity of the SelS gene, and further results revealed that PTX significantly inhibited the tunicamycin‑induced upregulation of SelS at the mRNA and protein levels in HepG2 and HEK293T cells. In addition, PTX was able to efficiently inhibit the expression of the ER stress marker, glucose‑regulated protein 78, in ER stress, indicating that PTX may reverse ER stress. Taken together, these results suggest that PTX is able to inhibit SelS expression during ER stress and attenuate ER stress. PMID:27109260

  9. Involvement of endoplasmic reticulum stress response in orofacial inflammatory pain.

    PubMed

    Yang, Eun Sun; Bae, Jin Young; Kim, Tae Heon; Kim, Yun Sook; Suk, Kyoungho; Bae, Yong Chul

    2014-12-01

    Endoplasmic reticulum (ER) stress is involved in many neurological diseases and inflammatory responses. Inflammatory mediators induce neuronal damage and trigger the neuropathic or inflammatory pain. But there is very little data on the role of the ER stress response in pain mechanisms. In this study, we explored whether the ER stress response is involved in orofacial inflammatory pain by using a complete Freund's adjuvant (CFA)-injected rat model. The thermal pain hypersensitivity increased significantly after CFA injection. We found that the protein and mRNA levels of ER stress response genes, GRP78/Bip and p-eIF2α, increased significantly in trigeminal ganglion (TG) of CFA-injected rats compared to control animals. In immunofluorescence analysis, a significant increase of GRP78 and p-eIF2α immunopositive neurons was observed in CFA-injected TG compared to control TG. When we administered an ER stress modulator, salubrinal, CFA-induced thermal pain hypersensitivity was temporally reduced. Thus, our study suggests that ER stress responses in TG neurons contribute to CFA-induced inflammatory pain, and may comprise an important molecular mechanism underlying the orofacial inflammatory pain pathway. PMID:25548537

  10. The Endoplasmic Reticulum and the Unfolded Protein Response

    PubMed Central

    Malhotra, Jyoti D.; Kaufman, Randal J.

    2009-01-01

    The endoplasmic reticulum (ER) is the site where proteins enter the secretory pathway. Proteins are translocated into the ER lumen in an unfolded state and require protein chaperones and catalysts of protein folding to attain their final appropriate conformation. A sensitive surveillance mechanism exists to prevent misfolded proteins from transiting the secretory pathway and ensures that persistently misfolded proteins are directed towards a degradative pathway. In addition, those processes that prevent accumulation of unfolded proteins in the ER lumen are highly regulated by an intracellular signaling pathway known as the unfolded protein response (UPR). The UPR provides a mechanism by which cells can rapidly adapt to alterations in client protein-folding load in the ER lumen by expanding the capacity for protein folding. In addition, a variety of insults that disrupt protein folding in the ER lumen also activate the UPR. These include changes in intralumenal calcium, altered glycosylation, nutrient deprivation, pathogen infection, expression of folding-defective proteins, and changes in redox status. Persistent protein misfolding initiates apoptotic cascades that are now known to play fundamental roles in the pathogenesis of multiple human diseases including diabetes, atherosclerosis and neurodegenerative diseases. PMID:18023214

  11. Diverse roles of endoplasmic reticulum stress sensors in bacterial infection.

    PubMed

    Pillich, Helena; Loose, Maria; Zimmer, Klaus-Peter; Chakraborty, Trinad

    2016-12-01

    Bacterial infection often leads to cellular damage, primarily marked by loss of cellular integrity and cell death. However, in recent years, it is being increasingly recognized that, in individual cells, there are graded responses collectively termed cell-autonomous defense mechanisms that induce cellular processes designed to limit cell damage, enable repair, and eliminate bacteria. Many of these responses are triggered not by detection of a particular bacterial effector or ligand but rather by their effects on key cellular processes and changes in homeostasis induced by microbial effectors when recognized. These in turn lead to a decrease in essential cellular functions such as protein translation or mitochondrial respiration and the induction of innate immune responses that may be specific to the cellular deficit induced. These processes are often associated with specific cell compartments, e.g., the endoplasmic reticulum (ER). Under non-infection conditions, these systems are generally involved in sensing cellular stress and in inducing and orchestrating the subsequent cellular response. Thus, perturbations of ER homeostasis result in accumulation of unfolded proteins which are detected by ER stress sensors in order to restore the normal condition. The ER is also important during bacterial infection, and bacterial effectors that activate the ER stress sensors have been discovered. Increasing evidence now indicate that bacteria have evolved strategies to differentially activate different arms of ER stress sensors resulting in specific host cell response. In this review, we will describe the mechanisms used by bacteria to activate the ER stress sensors and discuss their role during infection.

  12. Endoplasmic reticulum localization and activity of maize auxin biosynthetic enzymes.

    PubMed

    Kriechbaumer, Verena; Seo, Hyesu; Park, Woong June; Hawes, Chris

    2015-09-01

    Auxin is a major growth hormone in plants and the first plant hormone to be discovered and studied. Active research over >60 years has shed light on many of the molecular mechanisms of its action including transport, perception, signal transduction, and a variety of biosynthetic pathways in various species, tissues, and developmental stages. The complexity and redundancy of the auxin biosynthetic network and enzymes involved raises the question of how such a system, producing such a potent agent as auxin, can be appropriately controlled at all. Here it is shown that maize auxin biosynthesis takes place in microsomal as well as cytosolic cellular fractions from maize seedlings. Most interestingly, a set of enzymes shown to be involved in auxin biosynthesis via their activity and/or mutant phenotypes and catalysing adjacent steps in YUCCA-dependent biosynthesis are localized to the endoplasmic reticulum (ER). Positioning of auxin biosynthetic enzymes at the ER could be necessary to bring auxin biosynthesis in closer proximity to ER-localized factors for transport, conjugation, and signalling, and allow for an additional level of regulation by subcellular compartmentation of auxin action. Furthermore, it might provide a link to ethylene action and be a factor in hormonal cross-talk as all five ethylene receptors are ER localized.

  13. Regulation of endoplasmic reticulum turnover by selective autophagy.

    PubMed

    Khaminets, Aliaksandr; Heinrich, Theresa; Mari, Muriel; Grumati, Paolo; Huebner, Antje K; Akutsu, Masato; Liebmann, Lutz; Stolz, Alexandra; Nietzsche, Sandor; Koch, Nicole; Mauthe, Mario; Katona, Istvan; Qualmann, Britta; Weis, Joachim; Reggiori, Fulvio; Kurth, Ingo; Hübner, Christian A; Dikic, Ivan

    2015-06-18

    The endoplasmic reticulum (ER) is the largest intracellular endomembrane system, enabling protein and lipid synthesis, ion homeostasis, quality control of newly synthesized proteins and organelle communication. Constant ER turnover and modulation is needed to meet different cellular requirements and autophagy has an important role in this process. However, its underlying regulatory mechanisms remain unexplained. Here we show that members of the FAM134 reticulon protein family are ER-resident receptors that bind to autophagy modifiers LC3 and GABARAP, and facilitate ER degradation by autophagy ('ER-phagy'). Downregulation of FAM134B protein in human cells causes an expansion of the ER, while FAM134B overexpression results in ER fragmentation and lysosomal degradation. Mutant FAM134B proteins that cause sensory neuropathy in humans are unable to act as ER-phagy receptors. Consistently, disruption of Fam134b in mice causes expansion of the ER, inhibits ER turnover, sensitizes cells to stress-induced apoptotic cell death and leads to degeneration of sensory neurons. Therefore, selective ER-phagy via FAM134 proteins is indispensable for mammalian cell homeostasis and controls ER morphology and turnover in mice and humans.

  14. LDL–cholesterol transport to the endoplasmic reticulum: current concepts

    PubMed Central

    Pfisterer, Simon G.; Peränen, Johan; Ikonen, Elina

    2016-01-01

    Purpose of review In this article, we summarize the present information related to the export of LDL-derived cholesterol from late endosomes, with a focus on Nieman-Pick disease, type C1 (NPC1) cholesterol delivery toward the endoplasmic reticulum (ER). We review data suggesting that several pathways may operate in parallel, including membrane transport routes and membrane contact sites (MCSs). Recent findings There is increasing appreciation that MCSs provide an important mechanism for intermembrane lipid transfer. In late endosome–ER contacts, three protein bridges involving oxysterol binding protein related protein (ORP)1L-vesicle associated membrane protein-associated protein (VAP), steroidogenic acute regulatory protein (StAR)D3-VAP and ORP5-NPC1 proteins have been reported. How much they contribute to the flux of LDL–cholesterol to the ER is currently open. Studies for lipid transfer via MCSs have been most advanced in Saccharomyces cerevisiae. Recently, a new sterol-binding protein family conserved between yeast and man was identified. Its members localize at MCSs and were named lipid transfer protein anchored at membrane contact sites (Lam) proteins. In yeast, sterol transfer between the ER and the yeast lysosome may be facilitated by a Lam protein. Summary Increasing insights into the role of MCSs in directional sterol delivery between membranes propose that they might provide routes for LDL–cholesterol transfer to the ER. Future work should reveal which specific contacts may operate for this, and how they are controlled by cholesterol homeostatic machineries. PMID:27054443

  15. Endoplasmic Reticulum Stress in Beta Cells and Development of Diabetes

    PubMed Central

    Fonseca, Sonya G.; Burcin, Mark; Gromada, Jesper; Urano, Fumihiko

    2009-01-01

    The endoplasmic reticulum (ER) is a cellular compartment responsible for multiple important cellular functions including the biosynthesis and folding of newly synthesized proteins destined for secretion, such as insulin. A myriad of pathological and physiological factors perturb ER function and cause dysregulation of ER homeostasis, leading to ER stress. ER stress elicits a signaling cascade to mitigate stress, the Unfolded Protein Response (UPR). As long as the UPR can relieve stress, cells can produce the proper amount of proteins and maintain ER homeostasis. If the UPR, however, fails to maintain ER homeostasis, cells will undergo apoptosis. Activation of the UPR is critical to the survival of insulin-producing pancreatic β-cells with high secretory protein production. Any disruption of ER homeostasis in β-cells can lead to cell death and contribute to the pathogenesis of diabetes. There are several models of ER stress-mediated diabetes. In this review, we outline the underlying molecular mechanisms of ER stress-mediated β-cell dysfunction and death during the progression of diabetes. PMID:19665428

  16. Endoplasmic reticulum stress regulation in hematopoietic stem cells.

    PubMed

    Miharada, Kenichi

    2016-08-01

    Adult hematopoietic stem cells (HSCs) reside in bone marrow and are maintained in a dormant state within a special microenvironment, their so-called "niche". Detaching from the niche induces cell cycle progression, resulting in a reduction of the reconstitution capacity of HSCs. In contrast, fetal liver HSCs actively divide without losing their stem cell potentials. Thus, it has been unclear what types of cellular responses and metabolic changes occur in growing HSCs. We previously discovered that HSCs express relatively low levels of endoplasmic reticulum (ER) chaperone proteins governing protein folding, making HSCs vulnerable to an elevation of stress signals caused by accumulation of un-/misfolded proteins (ER stress) upon in vitro culture. Interestingly, fetal liver HSCs do not show ER stress elevation despite unchanged levels of chaperone proteins. Our latest studies utilizing multiple mouse models revealed that in the fetal liver bile acids as chemical chaperones play a key role supporting the protein folding which results in the suppression of ER stress induction. These findings highlight the importance of ER stress regulations in hematopoiesis. PMID:27599423

  17. Endoplasmic reticulum stress response in yeast and humans

    PubMed Central

    Wu, Haoxi; Ng, Benjamin S. H.; Thibault, Guillaume

    2014-01-01

    Stress pathways monitor intracellular systems and deploy a range of regulatory mechanisms in response to stress. One of the best-characterized pathways, the UPR (unfolded protein response), is an intracellular signal transduction pathway that monitors ER (endoplasmic reticulum) homoeostasis. Its activation is required to alleviate the effects of ER stress and is highly conserved from yeast to human. Although metazoans have three UPR outputs, yeast cells rely exclusively on the Ire1 (inositol-requiring enzyme-1) pathway, which is conserved in all Eukaryotes. In general, the UPR program activates hundreds of genes to alleviate ER stress but it can lead to apoptosis if the system fails to restore homoeostasis. In this review, we summarize the major advances in understanding the response to ER stress in Sc (Saccharomyces cerevisiae), Sp (Schizosaccharomyces pombe) and humans. The contribution of solved protein structures to a better understanding of the UPR pathway is discussed. Finally, we cover the interplay of ER stress in the development of diseases. PMID:24909749

  18. Protein Bodies in Leaves Exchange Contents through the Endoplasmic Reticulum

    PubMed Central

    Saberianfar, Reza; Sattarzadeh, Amirali; Joensuu, Jussi J.; Kohalmi, Susanne E.; Menassa, Rima

    2016-01-01

    Protein bodies (PBs) are organelles found in seeds whose main function is the storage of proteins that are used during germination for sustaining growth. PBs can also be induced to form in leaves when foreign proteins are produced at high levels in the endoplasmic reticulum (ER) and when fused to one of three tags: Zera®, elastin-like polypeptides (ELP), or hydrophobin-I (HFBI). In this study, we investigate the differences between ELP, HFBI and Zera PB formation, packing, and communication. Our results confirm the ER origin of all three fusion-tag-induced PBs. We show that secretory pathway proteins can be sequestered into all types of PBs but with different patterns, and that different fusion tags can target a specific protein to different PBs. Zera PBs are mobile and dependent on actomyosin motility similar to ELP and HFBI PBs. We show in vivo trafficking of proteins between PBs using GFP photoconversion. We also show that protein trafficking between ELP or HFBI PBs is faster and proteins travel further when compared to Zera PBs. Our results indicate that fusion-tag-induced PBs do not represent terminally stored cytosolic organelles, but that they form in, and remain part of the ER, and dynamically communicate with each other via the ER. We hypothesize that the previously documented PB mobility along the actin cytoskeleton is associated with ER movement rather than independent streaming of detached organelles. PMID:27242885

  19. Calreticulin: non-endoplasmic reticulum functions in physiology and disease

    PubMed Central

    Gold, Leslie I.; Eggleton, Paul; Sweetwyne, Mariya T.; Van Duyn, Lauren B.; Greives, Matthew R.; Naylor, Sara-Megumi; Michalak, Marek; Murphy-Ullrich, Joanne E.

    2010-01-01

    Calreticulin (CRT), when localized to the endoplasmic reticulum (ER), has important functions in directing proper conformation of proteins and glycoproteins, as well as in homeostatic control of cytosolic and ER calcium levels. There is also steadily accumulating evidence for diverse roles for CRT localized outside the ER, including data suggesting important roles for CRT localized to the outer cell surface of a variety of cell types, in the cytosol, and in the extracellular matrix (ECM). Furthermore, the addition of exogenous CRT rescues numerous CRT-driven functions, such as adhesion, migration, phagocytosis, and immunoregulatory functions of CRT-null cells. Recent studies show that topically applied CRT has diverse and profound biological effects that enhance cutaneous wound healing in animal models. This evidence for extracellular bioactivities of CRT has provided new insights into this classically ER-resident protein, despite a lack of knowledge of how CRT exits from the ER to the cell surface or how it is released into the extracellular milieu. Nonetheless, it has become clear that CRT is a multicompartmental protein that regulates a wide array of cellular responses important in physiological and pathological processes, such as wound healing, the immune response, fibrosis, and cancer.—Gold, L. I., Eggleton, P., Sweetwyne, M. T., Van Duyn, L. B., Greives, M. R., Naylor, S.-M., Michalak, M., Murphy-Ullrich, J. E. Calreticulin: non-endoplamic reticulum functions in physiology and disease. PMID:19940256

  20. Proper symmetric and asymmetric endoplasmic reticulum partitioning requires astral microtubules.

    PubMed

    Smyth, Jeremy T; Schoborg, Todd A; Bergman, Zane J; Riggs, Blake; Rusan, Nasser M

    2015-08-01

    Mechanisms that regulate partitioning of the endoplasmic reticulum (ER) during cell division are largely unknown. Previous studies have mostly addressed ER partitioning in cultured cells, which may not recapitulate physiological processes that are critical in developing, intact tissues. We have addressed this by analysing ER partitioning in asymmetrically dividing stem cells, in which precise segregation of cellular components is essential for proper development and tissue architecture. We show that in Drosophila neural stem cells, called neuroblasts, the ER asymmetrically partitioned to centrosomes early in mitosis. This correlated closely with the asymmetric nucleation of astral microtubules (MTs) by centrosomes, suggesting that astral MT association may be required for ER partitioning by centrosomes. Consistent with this, the ER also associated with astral MTs in meiotic Drosophila spermatocytes and during syncytial embryonic divisions. Disruption of centrosomes in each of these cell types led to improper ER partitioning, demonstrating the critical role for centrosomes and associated astral MTs in this process. Importantly, we show that the ER also associated with astral MTs in cultured human cells, suggesting that this centrosome/astral MT-based partitioning mechanism is conserved across animal species. PMID:26289801

  1. Chemical chaperones mitigate experimental asthma by attenuating endoplasmic reticulum stress.

    PubMed

    Makhija, Lokesh; Krishnan, Veda; Rehman, Rakhshinda; Chakraborty, Samarpana; Maity, Shuvadeep; Mabalirajan, Ulaganathan; Chakraborty, Kausik; Ghosh, Balaram; Agrawal, Anurag

    2014-05-01

    Endoplasmic reticulum (ER) stress and consequent unfolded protein response (UPR) are important in inflammation but have been poorly explored in asthma. We used a mouse model of allergic airway inflammation (AAI) with features of asthma to understand the role of ER stress and to explore potential therapeutic effects of inhaled chemical chaperones, which are small molecules that can promote protein folding and diminish UPR. UPR markers were initially measured on alternate days during a 7-day daily allergen challenge model. UPR markers increased within 24 hours after the first allergen challenge and peaked by the third challenge, before AAI was fully established (from the fifth challenge onward). Three chemical chaperones-glycerol, trehalose, and trimethylamine-N-oxide (TMAO)-were initially administered during allergen challenge (preventive regimen). TMAO, the most effective of these chemical chaperones and 4-phenylbutyric acid, a chemical chaperone currently in clinical trials, were further tested for potential therapeutic activities after AAI was established (therapeutic regimen). Chemical chaperones showed a dose-dependent reduction in UPR markers, airway inflammation, and remodeling in both regimens. Our results indicate an early and important role of the ER stress pathway in asthma pathogenesis and show therapeutic potential for chemical chaperones.

  2. Low molecular weight Abeta induces collapse of endoplasmic reticulum.

    PubMed

    Lai, Cora Sau-Wan; Preisler, Julie; Baum, Larry; Lee, Daniel Hong-Seng; Ng, Ho-Keung; Hugon, Jacques; So, Kwok-Fai; Chang, Raymond Chuen-Chung

    2009-05-01

    The endoplasmic reticulum (ER) is a dynamic multifunction organelle that is responsible for Ca(2+) homeostasis, protein folding, post-translational modification, protein degradation, and transportation of nascent proteins. Disruption of ER architecture might affect the normal physiology of the cell. In yeast, expansion of the ER is observed under unfolded protein response (UPR) and subsequently induces autophagy initiated from the ER. Here, we found that soluble low molecular weight of Abeta disrupted the anchoring between ER and microtubules (MT) and induced collapse of ER. In addition, it decreased the stability of MT. Subsequently, low molecular weight Abeta triggered autophagy and enhanced lysosomal degradation, as shown by electron microscopy and live-cell imaging. Dysfunction of ER can be further proved in postmortem AD brain and transgenic mice bearing APP Swedish mutation by immunohistochemical analysis of calreticulin. Treatment with Taxol, a MT-stabilizing agent, could partially inhibit collapse of the ER and induction of autophagy. The results show that Abeta-induced disruption of MT can affect the architecture of the ER. Collapse/aggregation of the ER may play an important role in Abeta peptide-triggered neurodegenerative processes.

  3. Involvement of Endoplasmic Reticulum Stress Response in Orofacial Inflammatory Pain

    PubMed Central

    Yang, Eun Sun; Bae, Jin Young; Kim, Tae Heon; Kim, Yun Sook; Suk, Kyoungho

    2014-01-01

    Endoplasmic reticulum (ER) stress is involved in many neurological diseases and inflammatory responses. Inflammatory mediators induce neuronal damage and trigger the neuropathic or inflammatory pain. But there is very little data on the role of the ER stress response in pain mechanisms. In this study, we explored whether the ER stress response is involved in orofacial inflammatory pain by using a complete Freund's adjuvant (CFA)-injected rat model. The thermal pain hypersensitivity increased significantly after CFA injection. We found that the protein and mRNA levels of ER stress response genes, GRP78/Bip and p-eIF2α, increased significantly in trigeminal ganglion (TG) of CFA-injected rats compared to control animals. In immunofluorescence analysis, a significant increase of GRP78 and p-eIF2α immunopositive neurons was observed in CFA-injected TG compared to control TG. When we administered an ER stress modulator, salubrinal, CFA-induced thermal pain hypersensitivity was temporally reduced. Thus, our study suggests that ER stress responses in TG neurons contribute to CFA-induced inflammatory pain, and may comprise an important molecular mechanism underlying the orofacial inflammatory pain pathway. PMID:25548537

  4. Endoplasmic Reticulum Calcium Regulates Epidermal Barrier Response and Desmosomal Structure

    PubMed Central

    Celli, Anna; Crumrine, Debra; Meyer, Jason M.; Mauro, Theodora M.

    2016-01-01

    Ca2+ fluxes direct keratinocyte differentiation, cell-to-cell adhesion, migration, and epidermal barrier homeostasis. We previously showed that intracellular Ca2+ stores constitute a major portion of the calcium gradient especially in the stratum granulosum. Loss of the calcium gradient triggers epidermal barrier homeostatic responses. In this report, using unfixed ex vivo epidermis and human epidermal equivalents we show that endoplasmic reticulum (ER) Ca2+ is released in response to barrier perturbation, and that this release constitutes the major shift in epidermal Ca2+ seen after barrier perturbation. We find that ER Ca2+ release correlates with a transient increase in extracellular Ca2+. Lastly, we show that ER calcium release resulting from barrier perturbation triggers transient desmosomal remodeling, seen as an increase in extracellular space and a loss of the desmosomal intercellular midline. Topical application of thapsigargin, which inhibits the ER Ca2+ ATPase activity without compromising barrier integrity, also leads to desmosomal remodeling and loss of the midline structure. These experiments establish the ER Ca2+ store as a master regulator of the Ca2+ gradient response to epidermal barrier perturbation, and suggest that ER Ca2+ homeostasis also modulates normal desmosomal reorganization, both at rest and after acute barrier perturbation. PMID:27255610

  5. Endoplasmic Reticulum Stress Interacts With Inflammation in Human Diseases

    PubMed Central

    Cao, Stewart Siyan; Luo, Katherine L.; Shi, Lynn

    2015-01-01

    The endoplasmic reticulum is a critical organelle for normal cell function and homeostasis. Disturbed protein folding process in the ER, termed ER stress, leads to the activation of unfolded protein response (UPR) that encompasses a complex network of intracellular signaling pathways. The UPR can either restore ER homeostasis or activate pro-apoptotic pathways depending on specific insults, intensity and duration of the stress, and cell types. ER stress and the UPR have recently been linked to inflammation in a variety of human pathologies including autoimmune diseases, infection, neurodegenerative disease, and metabolic disorders. In the cell, ER stress and inflammatory signaling share extensive regulators and effectors in a broad spectrum of biological processes. In spite of different etiologies, the two signaling pathways were shown to form a vicious cycle in exacerbating cellular dysfunction and causing apoptosis in many cells and tissues. However, the interaction between ER stress and inflammation in many of these diseases remains elusive. Further understanding of those issues may enable the development of novel therapies that spontaneously target these pathogenic pathways. PMID:26201832

  6. Endoplasmic reticulum localization and activity of maize auxin biosynthetic enzymes.

    PubMed

    Kriechbaumer, Verena; Seo, Hyesu; Park, Woong June; Hawes, Chris

    2015-09-01

    Auxin is a major growth hormone in plants and the first plant hormone to be discovered and studied. Active research over >60 years has shed light on many of the molecular mechanisms of its action including transport, perception, signal transduction, and a variety of biosynthetic pathways in various species, tissues, and developmental stages. The complexity and redundancy of the auxin biosynthetic network and enzymes involved raises the question of how such a system, producing such a potent agent as auxin, can be appropriately controlled at all. Here it is shown that maize auxin biosynthesis takes place in microsomal as well as cytosolic cellular fractions from maize seedlings. Most interestingly, a set of enzymes shown to be involved in auxin biosynthesis via their activity and/or mutant phenotypes and catalysing adjacent steps in YUCCA-dependent biosynthesis are localized to the endoplasmic reticulum (ER). Positioning of auxin biosynthetic enzymes at the ER could be necessary to bring auxin biosynthesis in closer proximity to ER-localized factors for transport, conjugation, and signalling, and allow for an additional level of regulation by subcellular compartmentation of auxin action. Furthermore, it might provide a link to ethylene action and be a factor in hormonal cross-talk as all five ethylene receptors are ER localized. PMID:26139824

  7. Sel1L is indispensable for mammalian endoplasmic reticulum-associated degradation, endoplasmic reticulum homeostasis, and survival

    PubMed Central

    Sun, Shengyi; Shi, Guojun; Han, Xuemei; Francisco, Adam B.; Ji, Yewei; Mendonça, Nuno; Liu, Xiaojing; Locasale, Jason W.; Simpson, Kenneth W.; Duhamel, Gerald E.; Kersten, Sander; Yates, John R.; Long, Qiaoming; Qi, Ling

    2014-01-01

    Suppressor/Enhancer of Lin-12-like (Sel1L) is an adaptor protein for the E3 ligase hydroxymethylglutaryl reductase degradation protein 1 (Hrd1) involved in endoplasmic reticulum-associated degradation (ERAD). Sel1L’s physiological importance in mammalian ERAD, however, remains to be established. Here, using the inducible Sel1L knockout mouse and cell models, we show that Sel1L is indispensable for Hrd1 stability, ER homeostasis, and survival. Acute loss of Sel1L leads to premature death in adult mice within 3 wk with profound pancreatic atrophy. Contrary to current belief, our data show that mammalian Sel1L is required for Hrd1 stability and ERAD function both in vitro and in vivo. Sel1L deficiency disturbs ER homeostasis, activates ER stress, attenuates translation, and promotes cell death. Serendipitously, using a biochemical approach coupled with mass spectrometry, we found that Sel1L deficiency causes the aggregation of both small and large ribosomal subunits. Thus, Sel1L is an indispensable component of the mammalian Hrd1 ERAD complex and ER homeostasis, which is essential for protein translation, pancreatic function, and cellular and organismal survival. PMID:24453213

  8. Reduced Endoplasmic Reticulum Luminal Calcium Links Saturated Fatty Acid-Mediated Endoplasmic Reticulum Stress and Cell Death in Liver Cells

    PubMed Central

    Wei, Yuren; Wang, Dong; Gentile, Christopher L.; Pagliassotti, Michael J.

    2010-01-01

    Chronic exposure to elevated free fatty acids, in particular long chain saturated fatty acids, provokes endoplasmic reticulum (ER) stress and cell death in a number of cell types. The perturbations to the ER that instigate ER stress and activation of the unfolded protein in response to fatty acids in hepatocytes have not been identified. The present study employed H4IIE liver cells and primary rat hepatocytes to examine the hypothesis that saturated fatty acids induce ER stress via effects on ER luminal calcium stores. Exposure of H4IIE liver cells and primary hepatocytes to palmitate and stearate reduced thapsigargin-sensitive calcium stores and biochemical markers of ER stress over similar time courses (6h). These changes preceded cell death, which was only observed at later time points (16h). Co-incubation with oleate prevented the reduction in calcium stores, induction of ER stress markers and cell death observed in response to palmitate. Inclusion of calcium chelators, BAPTA-AM or EGTA, reduced palmitate- and stearate-mediated enrichment of cytochrome c in post-mitochondrial supernatant fractions and cell death. These data suggest that redistribution of ER luminal calcium contributes to long chain saturated fatty acid-mediated ER stress and cell death. PMID:19444596

  9. Nonequilibrium flows with smooth particle applied mechanics

    SciTech Connect

    Kum, O.

    1995-07-01

    Smooth particle methods are relatively new methods for simulating solid and fluid flows through they have a 20-year history of solving complex hydrodynamic problems in astrophysics, such as colliding planets and stars, for which correct answers are unknown. The results presented in this thesis evaluate the adaptability or fitness of the method for typical hydrocode production problems. For finite hydrodynamic systems, boundary conditions are important. A reflective boundary condition with image particles is a good way to prevent a density anomaly at the boundary and to keep the fluxes continuous there. Boundary values of temperature and velocity can be separately controlled. The gradient algorithm, based on differentiating the smooth particle expression for (u{rho}) and (T{rho}), does not show numerical instabilities for the stress tensor and heat flux vector quantities which require second derivatives in space when Fourier`s heat-flow law and Newton`s viscous force law are used. Smooth particle methods show an interesting parallel linking to them to molecular dynamics. For the inviscid Euler equation, with an isentropic ideal gas equation of state, the smooth particle algorithm generates trajectories isomorphic to those generated by molecular dynamics. The shear moduli were evaluated based on molecular dynamics calculations for the three weighting functions, B spline, Lucy, and Cusp functions. The accuracy and applicability of the methods were estimated by comparing a set of smooth particle Rayleigh-Benard problems, all in the laminar regime, to corresponding highly-accurate grid-based numerical solutions of continuum equations. Both transient and stationary smooth particle solutions reproduce the grid-based data with velocity errors on the order of 5%. The smooth particle method still provides robust solutions at high Rayleigh number where grid-based methods fails.

  10. Turbulent flow in smooth and rough pipes.

    PubMed

    Allen, J J; Shockling, M A; Kunkel, G J; Smits, A J

    2007-03-15

    Recent experiments at Princeton University have revealed aspects of smooth pipe flow behaviour that suggest a more complex scaling than previously noted. In particular, the pressure gradient results yield a new friction factor relationship for smooth pipes, and the velocity profiles indicate the presence of a power-law region near the wall and, for Reynolds numbers greater than about 400x103 (R+>9x103), a logarithmic region further out. New experiments on a rough pipe with a honed surface finish with krms/D=19.4x10-6, over a Reynolds number range of 57x103-21x106, show that in the transitionally rough regime this surface follows an inflectional friction factor relationship rather than the monotonic relationship given in the Moody diagram. Outer-layer scaling of the mean velocity data and streamwise turbulence intensities for the rough pipe show excellent collapse and provide strong support for Townsend's outer-layer similarity hypothesis for rough-walled flows. The streamwise rough-wall spectra also agree well with the corresponding smooth-wall data. The pipe exhibited smooth behaviour for ks+ < or =3.5, which supports the suggestion that the original smooth pipe was indeed hydraulically smooth for ReD< or =24x106. The relationship between the velocity shift, DeltaU/utau, and the roughness Reynolds number, ks+, has been used to generalize the form of the transition from smooth to fully rough flow for an arbitrary relative roughness krms/D. These predictions apply for honed pipes when the separation of pipe diameter to roughness height is large, and they differ significantly from the traditional Moody curves.

  11. Gene transfer by adenovirus in smooth muscle cells.

    PubMed

    Yu, M F; Ewaskiewicz, J I; Adda, S; Bailey, K; Harris, V; Sosnoski, D; Tomasic, M; Wilson, J; Kotlikoff, M I

    1996-08-01

    We report adenovirus-mediated gene transfer into airway smooth muscle cells in cultured cells and organ-cultured tracheal segments. Incubation of cultured rat tracheal myocytes with virus (5 x 10(8) pfu/ml) for 6 h resulted in beta-galactosidase expression in 94.8 +/- 2.5% of cells (n = 4). Following incubation of thin (less than 200 microns diameter) equine trachealis muscle segments with virus in organ culture (5 x 10(8)-5 x 10(10) pfu/ml) the average expression of the Lac Z gene was approximately 19 +/- 10% (n = 9). Expression was markedly improved, however, in segments from neonatal rats (13-21 days). In two experiments in which the mucosa and serosa were removed, nearly all cells expressed beta-galactosidase, whereas in a third experiment in which the tissue was not dissected, about 40% of cells were stained. Viral infection had no effect on tension development of strips following organ culture. In vitro gene transfer may provide a useful method to alter protein expression and examine the effect of this alteration on excitation/contraction coupling in smooth muscle.

  12. Identification, characterization, and expression of the BiP endoplasmic reticulum resident chaperonins in Pneumocystis carinii.

    PubMed Central

    Stedman, T T; Buck, G A

    1996-01-01

    We have isolated, characterized, and examined the expression of the genes encoding BiP endoplasmic reticulum (ER) resident chaperonins responsible for transport, maturation, and proper folding of membrane and secreted proteins from two divergent strains of Pneumocystis carinii. The BiP genes, Pcbip and Prbip, from the P. c. carinii (prototype) strain and the P. c. rattus (variant) strain, respectively, are single-copy genes that reside on chromosomes of approximately 330 and approximately 350 kbp. Both genes encode approximately 72.5-kDa proteins that are most homologous to BiP genes from other organisms and exhibit the amino-terminal signal peptides and carboxyl-terminal ER retention sequences that are hallmarks of BiP proteins. We established short-term P. carinii cultures to examine expression and induction of Pcbip in response to heat shock, glucose starvation, inhibition of protein transport or N-linked glycosylation, and other conditions known to affect proper transport, glycosylation, and maturation of membrane and secreted proteins. These studies indicated that Pcbip mRNA is constitutively expressed but induced under conditions known to induce BiP expression in other organisms. In contrast to mammalian BiP genes but like other fungal BiP genes, P. carinii BiP mRNA levels are induced by heat shock. Finally, the Prbip and Pcbip coding sequences surprisingly exhibit only approximately 83% DNA and approximately 90% amino acid sequence identity and show only limited conservation in noncoding flanking and intron sequences. Analyses of the P. carinii BiP gene sequences support inclusion of P. carinii among the fungi but suggest a large divergence and possible speciation among P. carinii strains infecting a given host. PMID:8890193

  13. Improved metabolite profile smoothing for flux estimation.

    PubMed

    Dromms, Robert A; Styczynski, Mark P

    2015-09-01

    As genome-scale metabolic models become more sophisticated and dynamic, one significant challenge in using these models is to effectively integrate increasingly prevalent systems-scale metabolite profiling data into them. One common data processing step when integrating metabolite data is to smooth experimental time course measurements: the smoothed profiles can be used to estimate metabolite accumulation (derivatives), and thus the flux distribution of the metabolic model. However, this smoothing step is susceptible to the (often significant) noise in experimental measurements, limiting the accuracy of downstream model predictions. Here, we present several improvements to current approaches for smoothing metabolite time course data using defined functions. First, we use a biologically-inspired mathematical model function taken from transcriptional profiling and clustering literature that captures the dynamics of many biologically relevant transient processes. We demonstrate that it is competitive with, and often superior to, previously described fitting schemas, and may serve as an effective single option for data smoothing in metabolic flux applications. We also implement a resampling-based approach to buffer out sensitivity to specific data sets and allow for more accurate fitting of noisy data. We found that this method, as well as the addition of parameter space constraints, yielded improved estimates of concentrations and derivatives (fluxes) in previously described fitting functions. These methods have the potential to improve the accuracy of existing and future dynamic metabolic models by allowing for the more effective integration of metabolite profiling data.

  14. Manual tracking enhances smooth pursuit eye movements

    PubMed Central

    Niehorster, Diederick C.; Siu, Wilfred W. F.; Li, Li

    2015-01-01

    Previous studies have reported that concurrent manual tracking enhances smooth pursuit eye movements only when tracking a self-driven or a predictable moving target. Here, we used a control-theoretic approach to examine whether concurrent manual tracking enhances smooth pursuit of an unpredictable moving target. In the eye-hand tracking condition, participants used their eyes to track a Gaussian target that moved randomly along a horizontal axis. In the meantime, they used their dominant hand to move a mouse to control the horizontal movement of a Gaussian cursor to vertically align it with the target. In the eye-alone tracking condition, the target and cursor positions recorded in the eye-hand tracking condition were replayed, and participants only performed eye tracking of the target. Catch-up saccades were identified and removed from the recorded eye movements, allowing for a frequency-response analysis of the smooth pursuit response to unpredictable target motion. We found that the overall smooth pursuit gain was higher and the number of catch-up saccades made was less when eye tracking was accompanied by manual tracking than when not. We conclude that concurrent manual tracking enhances smooth pursuit. This enhancement is a fundamental property of eye-hand coordination that occurs regardless of the predictability of the target motion. PMID:26605840

  15. Endoplasmic reticulum stress: key promoter of rosacea pathogenesis.

    PubMed

    Melnik, Bodo C

    2014-12-01

    Recent scientific interest in the pathogenesis of rosacea focuses on abnormally high facial skin levels of cathelicidin and the trypsin-like serine protease kallikrein 5 (KLK5) that cleaves the cathelicidin precursor protein into the bioactive fragment LL-37, which exerts crucial proinflammatory, angiogenic and antimicrobial activities. Furthermore, increased expression of toll-like receptor 2 (TLR2) has been identified in rosacea skin supporting the participation of the innate immune system. Notably, TLRs are expressed on sensory neurons and increase neuronal excitability linking TLR signalling to the transmission of neuroinflammatory responses. It is the intention of this viewpoint to present a unifying concept that links all known clinical trigger factors of rosacea such as UV irradiation, heat, skin irritants and special foods to one converging point: enhanced endoplasmic reticulum (ER) stress that activates the unfolded protein response (UPR). ER stress via upregulation of transcription factor ATF4 increases TLR2 expression, resulting in enhanced production of cathelicidin and KLK5 mediating downstream proinflammatory, angiogenic and antimicrobial signalling. The presented concept identifies rosacea trigger factors as environmental stressors that enhance the skin's ER stress response. Exaggerated cutaneous ER stress that stimulates the TLR2-driven inflammatory response may involve sebocytes, keratinocytes, monocyte-macrophages and sensory cutaneous neurons. Finally, all antirosacea drugs are proposed to attenuate the ER stress signalling cascade at some point. Overstimulated ER stress signalling may have evolutionarily evolved as a compensatory mechanism to balance impaired vitamin D-driven LL-37-mediated antimicrobial defenses due to lower exposure of UV-B irradiation of the northern Celtic population. PMID:25047092

  16. Inhibition of Endoplasmic Reticulum Stress Improves Mouse Embryo Development

    PubMed Central

    Zhang, Jin Yu; Diao, Yun Fei; Kim, Hong Rye; Jin, Dong Il

    2012-01-01

    X-box binding protein-1 (XBP-1) is an important regulator of a subset of genes during endoplasmic reticulum (ER) stress. In the current study, we analyzed endogenous XBP-1 expression and localization, with a view to determining the effects of ER stress on the developmental competency of preimplantation embryos in mice. Fluorescence staining revealed that functional XBP-1 is localized on mature oocyte spindles and abundant in the nucleus at the germinal vesicle (GV) stage. However, in preimplantation embryos, XBP-1 was solely detected in the cytoplasm at the one-cell stage. The density of XBP-1 was higher in the nucleus than the cytoplasm at the two-cell, four-cell, eight-cell, morula, and blastocyst stages. Furthermore, RT-PCR analysis confirmed active XBP-1 mRNA splicing at all preimplantation embryo stages, except the one-cell stage. Tunicamycin (TM), an ER stress inducer used as a positive control, promoted an increase in the density of nuclear XBP-1 at the one-cell and two-cell stages. Similarly, culture medium supplemented with 25 mM sorbitol displayed a remarkable increase active XBP-1 expression in the nuclei of 1-cell and 2-cell embryos. Conversely, high concentrations of TM or sorbitol led to reduced nuclear XBP-1 density and significant ER stress-induced apoptosis. Tauroursodeoxycholic acid (TUDCA), a known inhibitor of ER stress, improved the rate of two-cell embryo development to blastocysts by attenuating the expression of active XBP-1 protein in the nucleus at the two-cell stage. Our data collectively suggest that endogenous XBP-1 plays a role in normal preimplantation embryonic development. Moreover, XBP-1 splicing is activated to generate a functional form in mouse preimplantation embryos during culture stress. TUDCA inhibits hyperosmolar-induced ER stress as well as ER stress-induced apoptosis during mouse preimplantation embryo development. PMID:22808162

  17. Endoplasmic reticulum stress: key promoter of rosacea pathogenesis.

    PubMed

    Melnik, Bodo C

    2014-12-01

    Recent scientific interest in the pathogenesis of rosacea focuses on abnormally high facial skin levels of cathelicidin and the trypsin-like serine protease kallikrein 5 (KLK5) that cleaves the cathelicidin precursor protein into the bioactive fragment LL-37, which exerts crucial proinflammatory, angiogenic and antimicrobial activities. Furthermore, increased expression of toll-like receptor 2 (TLR2) has been identified in rosacea skin supporting the participation of the innate immune system. Notably, TLRs are expressed on sensory neurons and increase neuronal excitability linking TLR signalling to the transmission of neuroinflammatory responses. It is the intention of this viewpoint to present a unifying concept that links all known clinical trigger factors of rosacea such as UV irradiation, heat, skin irritants and special foods to one converging point: enhanced endoplasmic reticulum (ER) stress that activates the unfolded protein response (UPR). ER stress via upregulation of transcription factor ATF4 increases TLR2 expression, resulting in enhanced production of cathelicidin and KLK5 mediating downstream proinflammatory, angiogenic and antimicrobial signalling. The presented concept identifies rosacea trigger factors as environmental stressors that enhance the skin's ER stress response. Exaggerated cutaneous ER stress that stimulates the TLR2-driven inflammatory response may involve sebocytes, keratinocytes, monocyte-macrophages and sensory cutaneous neurons. Finally, all antirosacea drugs are proposed to attenuate the ER stress signalling cascade at some point. Overstimulated ER stress signalling may have evolutionarily evolved as a compensatory mechanism to balance impaired vitamin D-driven LL-37-mediated antimicrobial defenses due to lower exposure of UV-B irradiation of the northern Celtic population.

  18. Endoplasmic Reticulum Membrane Reorganization Is Regulated by Ionic Homeostasis

    PubMed Central

    Varadarajan, Shankar; Bampton, Edward T. W.; Pellecchia, Maurizio; Dinsdale, David; Willars, Gary B.; Cohen, Gerald M.

    2013-01-01

    Recently we described a new, evolutionarily conserved cellular stress response characterized by a reversible reorganization of endoplasmic reticulum (ER) membranes that is distinct from canonical ER stress and the unfolded protein response (UPR). Apogossypol, a putative broad spectrum BCL-2 family antagonist, was the prototype compound used to induce this ER membrane reorganization. Following microarray analysis of cells treated with apogossypol, we used connectivity mapping to identify a wide range of structurally diverse chemicals from different pharmacological classes and established their ability to induce ER membrane reorganization. Such structural diversity suggests that the mechanisms initiating ER membrane reorganization are also diverse and a major objective of the present study was to identify potentially common features of these mechanisms. In order to explore this, we used hierarchical clustering of transcription profiles for a number of chemicals that induce membrane reorganization and discovered two distinct clusters. One cluster contained chemicals with known effects on Ca2+ homeostasis. Support for this was provided by the findings that ER membrane reorganization was induced by agents that either deplete ER Ca2+ (thapsigargin) or cause an alteration in cellular Ca2+ handling (calmodulin antagonists). Furthermore, overexpression of the ER luminal Ca2+ sensor, STIM1, also evoked ER membrane reorganization. Although perturbation of Ca2+ homeostasis was clearly one mechanism by which some agents induced ER membrane reorganization, influx of extracellular Na+ but not Ca2+ was required for ER membrane reorganization induced by apogossypol and the related BCL-2 family antagonist, TW37, in both human and yeast cells. Not only is this novel, non-canonical ER stress response evolutionary conserved but so also are aspects of the mechanism of formation of ER membrane aggregates. Thus perturbation of ionic homeostasis is important in the regulation of ER

  19. Melatonin and endoplasmic reticulum stress: relation to autophagy and apoptosis.

    PubMed

    Fernández, Anna; Ordóñez, Raquel; Reiter, Russel J; González-Gallego, Javier; Mauriz, José L

    2015-10-01

    Endoplasmic reticulum (ER) is a dynamic organelle that participates in a number of cellular functions by controlling lipid metabolism, calcium stores, and proteostasis. Under stressful situations, the ER environment is compromised, and protein maturation is impaired; this causes misfolded proteins to accumulate and a characteristic stress response named unfolded protein response (UPR). UPR protects cells from stress and contributes to cellular homeostasis re-establishment; however, during prolonged ER stress, UPR activation promotes cell death. ER stressors can modulate autophagy which in turn, depending of the situation, induces cell survival or death. Interactions of different autophagy- and apoptosis-related proteins and also common signaling pathways have been found, suggesting an interplay between these cellular processes, although their dynamic features are still unknown. A number of pathologies including metabolic, neurodegenerative and cardiovascular diseases, cancer, inflammation, and viral infections are associated with ER stress, leading to a growing interest in targeting components of the UPR as a therapeutic strategy. Melatonin has a variety of antioxidant, anti-inflammatory, and antitumor effects. As such, it modulates apoptosis and autophagy in cancer cells, neurodegeneration and the development of liver diseases as well as other pathologies. Here, we review the effects of melatonin on the main ER stress mechanisms, focusing on its ability to regulate the autophagic and apoptotic processes. As the number of studies that have analyzed ER stress modulation by this indole remains limited, further research is necessary for a better understanding of the crosstalk between ER stress, autophagy, and apoptosis and to clearly delineate the mechanisms by which melatonin modulates these responses.

  20. Cortisol promotes endoplasmic glucose production via pyridine nucleotide redox.

    PubMed

    Wang, Zengmin; Mick, Gail J; Xie, Rongrong; Wang, Xudong; Xie, Xuemei; Li, Guimei; McCormick, Kenneth L

    2016-04-01

    Both increased adrenal and peripheral cortisol production, the latter governed by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), contribute to the maintenance of fasting blood glucose. In the endoplasmic reticulum (ER), the pyridine nucleotide redox state (NADP/NADPH) is dictated by the concentration of glucose-6-phosphate (G6P) and the coordinated activities of two enzymes, hexose-6-phosphate dehydrogenase (H6PDH) and 11β-HSD1. However, luminal G6P may similarly serve as a substrate for hepatic glucose-6-phophatase (G6Pase). A tacit belief is that the G6P pool in the ER is equally accessible to both H6PDH and G6Pase. Based on our inhibition studies and kinetic analysis in isolated rat liver microsomes, these two aforesaid luminal enzymes do share the G6P pool in the ER, but not equally. Based on the kinetic modeling of G6P flux, the ER transporter for G6P (T1) preferentially delivers this substrate to G6Pase; hence, the luminal enzymes do not share G6P equally. Moreover, cortisol, acting through 11β-HSD1, begets a more reduced pyridine redox ratio. By altering this luminal redox ratio, G6P flux through H6PDH is restrained, allowing more G6P for the competing enzyme G6Pase. And, at low G6P concentrations in the ER lumen, which occur during fasting, this acute cortisol-induced redox adjustment promotes glucose production. This reproducible cortisol-driven mechanism has been heretofore unrecognized. PMID:26860459

  1. Smooth muscle actin and myosin expression in cultured airway smooth muscle cells.

    PubMed

    Wong, J Z; Woodcock-Mitchell, J; Mitchell, J; Rippetoe, P; White, S; Absher, M; Baldor, L; Evans, J; McHugh, K M; Low, R B

    1998-05-01

    In this study, the expression of smooth muscle actin and myosin was examined in cultures of rat tracheal smooth muscle cells. Protein and mRNA analyses demonstrated that these cells express alpha- and gamma-smooth muscle actin and smooth muscle myosin and nonmuscle myosin-B heavy chains. The expression of the smooth muscle specific actin and myosin isoforms was regulated in the same direction when growth conditions were changed. Thus, at confluency in 1 or 10% serum-containing medium as well as for low-density cells (50-60% confluent) deprived of serum, the expression of the smooth muscle forms of actin and myosin was relatively high. Conversely, in rapidly proliferating cultures at low density in 10% serum, smooth muscle contractile protein expression was low. The expression of nonmuscle myosin-B mRNA and protein was more stable and was upregulated only to a small degree in growing cells. Our results provide new insight into the molecular basis of differentiation and contractile function in airway smooth muscle cells.

  2. Effects of Se on the Diversity of SelT Synthesis and Distribution in Different Smooth Muscle Tissues in Rats.

    PubMed

    Guo, Mengyao; Gao, Xuejiao; Zhang, Naisheng; Qiu, Changwei; Li, Chengye; Deng, Ganzhen

    2016-04-01

    Selenium (Se) is a nutritionally essential trace element associated with health and disease, including many muscle diseases. Selenoprotein T (SelT) has been identified as a member of the redoxin protein family that includes selenocysteine, localizing to the endoplasmic reticulum. The synthesis of selenoprotein is influenced by Se. However, there is currently no data concerning the pattern of SelT expression in smooth muscle tissues. To investigate the effects of dietary Se on the expression of SelT, 90 rats were randomly allocated into three groups: LG, NG, and HG. The LG group was fed a basal diet deficient in Se (containing 0.023 mg/kg Se); the NG and HG groups were fed Se-supplemented diets containing either 0.3 or 1.5 mg/kg Se, respectively, for 90 days. The smooth muscle of the esophagus, trachea, stomach, intestine, and blood vessels was collected when the rats were 90 days old. The Se content in the blood and tissues was examined. The messenger RNA (mRNA) of selenocysteine-tRNA([Ser]Sec) synthase (SecS), selenophosphate synthetase 1 (SPS1), selenophosphate synthetase 2 (SPS2), and SelT were examined using qPCR, and SelT protein was detected by Western blotting. The results indicated that Se had an effect on the mRNA levels of SecS, with little effect on those of SPS1 in smooth muscle tissues. SelT was expressed in the smooth muscle tissues of blood vessels, esophagus, bronchus, stomach, and intestine, and the transcription of the SelT was very sensitive to dietary Se. Thus, SelT may play a major role in the mechanisms underlying the biological activity of Se in smooth muscle tissues. PMID:26280902

  3. Local, Optimization-based Simplicial Mesh Smoothing

    1999-12-09

    OPT-MS is a C software package for the improvement and untangling of simplicial meshes (triangles in 2D, tetrahedra in 3D). Overall mesh quality is improved by iterating over the mesh vertices and adjusting their position to optimize some measure of mesh quality, such as element angle or aspect ratio. Several solution techniques (including Laplacian smoothing, "Smart" Laplacian smoothing, optimization-based smoothing and several combinations thereof) and objective functions (for example, element angle, sin (angle), and aspectmore » ratio) are available to the user for both two and three-dimensional meshes. If the mesh contains invalid elements (those with negative area) a different optimization algorithm for mesh untangling is provided.« less

  4. Multiple predictor smoothing methods for sensitivity analysis.

    SciTech Connect

    Helton, Jon Craig; Storlie, Curtis B.

    2006-08-01

    The use of multiple predictor smoothing methods in sampling-based sensitivity analyses of complex models is investigated. Specifically, sensitivity analysis procedures based on smoothing methods employing the stepwise application of the following nonparametric regression techniques are described: (1) locally weighted regression (LOESS), (2) additive models, (3) projection pursuit regression, and (4) recursive partitioning regression. The indicated procedures are illustrated with both simple test problems and results from a performance assessment for a radioactive waste disposal facility (i.e., the Waste Isolation Pilot Plant). As shown by the example illustrations, the use of smoothing procedures based on nonparametric regression techniques can yield more informative sensitivity analysis results than can be obtained with more traditional sensitivity analysis procedures based on linear regression, rank regression or quadratic regression when nonlinear relationships between model inputs and model predictions are present.

  5. ibr: Iterative bias reduction multivariate smoothing

    SciTech Connect

    Hengartner, Nicholas W; Cornillon, Pierre-andre; Matzner - Lober, Eric

    2009-01-01

    Regression is a fundamental data analysis tool for relating a univariate response variable Y to a multivariate predictor X {element_of} E R{sup d} from the observations (X{sub i}, Y{sub i}), i = 1,...,n. Traditional nonparametric regression use the assumption that the regression function varies smoothly in the independent variable x to locally estimate the conditional expectation m(x) = E[Y|X = x]. The resulting vector of predicted values {cflx Y}{sub i} at the observed covariates X{sub i} is called a regression smoother, or simply a smoother, because the predicted values {cflx Y}{sub i} are less variable than the original observations Y{sub i}. Linear smoothers are linear in the response variable Y and are operationally written as {cflx m} = X{sub {lambda}}Y, where S{sub {lambda}} is a n x n smoothing matrix. The smoothing matrix S{sub {lambda}} typically depends on a tuning parameter which we denote by {lambda}, and that governs the tradeoff between the smoothness of the estimate and the goodness-of-fit of the smoother to the data by controlling the effective size of the local neighborhood over which the responses are averaged. We parameterize the smoothing matrix such that large values of {lambda} are associated to smoothers that averages over larger neighborhood and produce very smooth curves, while small {lambda} are associated to smoothers that average over smaller neighborhood to produce a more wiggly curve that wants to interpolate the data. The parameter {lambda} is the bandwidth for kernel smoother, the span size for running-mean smoother, bin smoother, and the penalty factor {lambda} for spline smoother.

  6. Endoplasmic filaments generate the motive force for rotational streaming in Nitella.

    PubMed

    Allen, N S

    1974-10-01

    The streaming endoplasm of characean cells has been shown to contain previously unreported endoplasmic filaments along which bending waves are observed under the light microscope using special techniques. The bending waves are similar to those propagated along sperm tails causing propulsion of sperm. In Nitella there is reason to believe that nearly all of the filaments are anchored in the cortex and that their beating propels the endoplasm in which they are suspended. This hypothesis is supported by calculations in which typical and average wave parameters have been inserted into the classical hydrodynamic equations derived for sperm tail bending waves. These calculations come within an order of magnitude of predicting the velocity of streaming and they show that waves of the character described, propagated along an estimated 52 m of endoplasmic filaments per cell, must generate a total motive force per cell within less than an order of magnitude of the forces measured experimentally by others. If we assume that undulating filaments produce the force driving the endoplasm, then the method described for measuring the motive force could lead to a lower than actual value for the motive force, since both centrifugation and vacuolar perfusion would reverse the orientation of some filaments. Observations of the initiation of particle translation in association with the filaments suggest that particle transport and wave propagation, which occur at the same velocity, may both be dependent on the same process. The possibility that some form of contractility provides the motive force for filament flection and particle transport is discussed.

  7. ENDOPLASMIC FILAMENTS GENERATE THE MOTIVE FORCE FOR ROTATIONAL STREAMING IN NITELLA

    PubMed Central

    Allen, Nina Strömgren

    1974-01-01

    The streaming endoplasm of characean cells has been shown to contain previously unreported endoplasmic filaments along which bending waves are observed under the light microscope using special techniques. The bending waves are similar to those propagated along sperm tails causing propulsion of sperm. In Nitella there is reason to believe that nearly all of the filaments are anchored in the cortex and that their beating propels the endoplasm in which they are suspended. This hypothesis is supported by calculations in which typical and average wave parameters have been inserted into the classical hydrodynamic equations derived for sperm tail bending waves. These calculations come within an order of magnitude of predicting the velocity of streaming and they show that waves of the character described, propagated along an estimated 52 m of endoplasmic filaments per cell, must generate a total motive force per cell within less than an order of magnitude of the forces measured experimentally by others. If we assume that undulating filaments produce the force driving the endoplasm, then the method described for measuring the motive force could lead to a lower than actual value for the motive force, since both centrifugation and vacuolar perfusion would reverse the orientation of some filaments. Observations of the initiation of particle translation in association with the filaments suggest that particle transport and wave propagation, which occur at the same velocity, may both be dependent on the same process. The possibility that some form of contractility provides the motive force for filament flection and particle transport is discussed. PMID:4608919

  8. Production of super-smooth articles

    SciTech Connect

    Duchane, D.V.

    1981-05-29

    Super-smooth rounded or formed articles made of thermoplastic materials including various poly(methyl methacrylate) or acrylonitrile-butadiene-styrene copolymers are produced by immersing the articles into a bath, the composition of which is slowly changed with time. The starting composition of the bath is made up of at least one solvent for the polymer and a diluent made up of at least one nonsolvent for the polymer and optional materials which are soluble in the bath. The resulting extremely smooth articles are useful as mandrels for laser fusion and should be useful for a wide variety of other purposes, for example lenses.

  9. Production of super-smooth articles

    DOEpatents

    Duchane, David V.

    1983-01-01

    Super-smooth rounded or formed articles made of thermoplastic materials including various poly(methyl methacrylate) or acrylonitrile-butadiene-styrene copolymers are produced by immersing the articles into a bath, the composition of which is slowly changed with time. The starting composition of the bath is made up of at least one solvent for the polymer and a diluent made up of at least one nonsolvent for the polymer and optional materials which are soluble in the bath. The resulting extremely smooth articles are useful as mandrels for laser fusion and should be useful for a wide variety of other purposes, for example lenses.

  10. Some cautionary remarks about smoothed particle hydrodynamics

    NASA Technical Reports Server (NTRS)

    Hernquist, Lars

    1993-01-01

    Potential difficulties with smoothed particle hydrodynamics are discussed. In particular, empirical tests are used to demonstrate that the errors resulting from the use of variable smoothing can be much larger than commonly believed. Fortunately, however, these errors, which are normally small, do not appear to promote instability on small scales, such as fragmentation in self-gravitating fluids. Still, while SPH remains a useful tool for many problems of astrophysical interest, a rigorous formulation of it, which is adaptive but still satisfies conservation properties, is clearly wanting.

  11. Geometrical Wake of a Smooth Flat Collimator

    SciTech Connect

    Stupakov, G.V.; /SLAC

    2011-09-09

    A transverse geometrical wake generated by a beam passing through a smooth flat collimator with a gradually varying gap between the upper and lower walls is considered. Based on generalization of the approach recently developed for a smooth circular taper we reduce the electromagnetic problem of the impedance calculation to the solution of two much simpler static problems - a magnetostatic and an electrostatic ones. The solution shows that in the limit of not very large frequencies, the impedance increases with the ratio h/d where h is the width and d is the distance between the collimating jaws. Numerical results are presented for the NLC Post Linac collimator.

  12. The deadly connection between endoplasmic reticulum, Ca2+, protein synthesis, and the endoplasmic reticulum stress response in malignant glioma cells

    PubMed Central

    Johnson, Guyla G.; White, Misti C.; Wu, Jian-He; Vallejo, Matthew; Grimaldi, Maurizio

    2014-01-01

    Background The endoplasmic reticulum (ER) is involved in Ca2+ signaling and protein processing. Accumulation of unfolded proteins following ER Ca2+ depletion triggers the ER stress response (ERSR), which facilitates protein folding and removal of damaged proteins and can induce cell death. Unfolded proteins bind to chaperones, such as the glucose-regulated protein (GRP)78 and cause the release of GRP78-repressed proteins executing ERSR. Methods Several glioma cell lines and primary astrocytes were used to analyze ERSR using standard western blots, reverse transcription–PCR, viability assays, and single cell Ca2+ imaging. Results ERSR induction with thapsigargin results in a more intense ERSR associated with a larger loss of ER Ca2+, activation of ER-associated caspases (4/12) and caspase 3, and a higher rate of malignant glioma cell death than in normal glial cells. Malignant glioma cells have higher levels of protein synthesis and expression of the translocon (a component of the ribosomal complex, guiding protein entry in the ER), the activity of which is associated with the loss of ER Ca2+. Our experiments confirm increased expression of the translocon in malignant glioma cells. In addition, blockade of the ribosome-translocon complex with agents differently affecting translocon Ca2+ permeability causes opposite effects on ERSR deployment and death of malignant glioma cells. Conclusions Excessive ER Ca2+ loss due to translocon activity appears to be responsible for the enhancement of ERSR, leading to the death of glioma cells. The results reveal a characteristic of malignant glioma cells that could be exploited to develop new therapeutic strategies to treat incurable glial malignancies. PMID:24569545

  13. Endocytosis of simian virus 40 into the endoplasmic reticulum

    SciTech Connect

    Kartenbeck, J.; Stukenbrok, H.; Helenius, A. )

    1989-12-01

    The endocytosis of SV-40 into CV-1 cells we studied using biochemical and ultrastructural techniques. The half-time of binding of ({sup 35}S)methionine-radiolabeled SV-40 to CV-1 cells was 25 min. Most of the incoming virus particles remained undegraded for several hours. Electron microscopy showed that some virus entered the endosomal/lysosomal pathway via coated vesicles, while the majority were endocytosed via small uncoated vesicles. After infection at high multiplicity, one third of total cell-associated virus was observed to enter the ER, starting 1-2 h after virus application. The viruses were present in large, tubular, smooth membrane networks generated as extentions of the ER. The results describe a novel and unique membrane transport pathway that allows endocytosed viral particles to be targeted from the plasma membrane to the ER.

  14. The Role of Endoplasmic Reticulum Stress and Unfolded Protein Response in Atherosclerosis.

    PubMed

    Ivanova, Ekaterina A; Orekhov, Alexander N

    2016-02-01

    Pathogenesis of atherosclerosis is a complex process involving several metabolic and signalling pathways. Accumulating evidence demonstrates that endoplasmic reticulum stress and associated apoptosis can be induced in the pathological conditions of atherosclerotic lesions and contribute to the disease progression. Notably, they may play a role in the development of vulnerable plaques that induce thrombosis and are therefore especially dangerous. Endoplasmic reticulum stress response is regulated by several signaling mechanisms that involve protein kinases and transcription factors. Some of these molecules can be regarded as potential therapeutic targets to improve treatment of atherosclerosis. In this review we will discuss the role of endoplasmic reticulum stress and apoptosis in atherosclerosis development in different cell types and summarize the current knowledge on potential therapeutic agents targeting molecules regulating these pathways and their possible use for anti-atherosclerotic therapy.

  15. Deubiquitination, a new player in Golgi to endoplasmic reticulum retrograde transport.

    PubMed

    Cohen, Mickaël; Stutz, Françoise; Dargemont, Catherine

    2003-12-26

    Modification by ubiquitin plays a major role in a broad array of cellular functions. Although reversal of this process, deubiquitination, likely represents an important regulatory step contributing to cellular homeostasis, functions of deubiquitination enzymes still remain poorly characterized. We have previously shown that the ubiquitin protease Ubp3p requires a co-factor, Bre5p, to specifically deubiquitinate the coat protein complex II (COPII) subunit Sec23p, which is involved in anterograde transport between endoplasmic reticulum and Golgi compartments. In the present report, we show that disruption of BRE5 gene also led to a defect in the retrograde transport from the Golgi to the endoplasmic reticulum. Further analysis indicate that the COPI subunit beta'-COP represents another substrate of the Ubp3p.Bre5p complex. All together, our results indicate that the Ubp3p.Bre5p deubiquitination complex co-regulates anterograde and retrograde transports between endoplasmic reticulum and Golgi compartments.

  16. [Role of endoplasmic reticulum-plasma membrane junctions in intracellular calcium homeostasis and cardiovascular disease].

    PubMed

    Zhao, Ming; Jia, Hang-Huan; Xu, Man; Yu, Xiao-Jiang; Liu, Long-Zhu; Zang, Wei-Jin

    2016-08-25

    Calcium overload is one of the important mechanisms of cardiovascular disease. Endoplasmic reticulum is an important organelle which regulates intracellular calcium homeostasis by uptake, storage and mobilization of calcium. So it plays a critical role in regulation of intracellular calcium homeostasis. Endoplasmic reticulum, which is widely distributed in cytoplasm, has a large number of membrane junction sites. Recent studies have reported that these junction sites are distributed on plasma membrane and organelle membranes (mitochondria, lysosomes, Golgi apparatus, etc.), separately. They could form complexes to regulate calcium transport. In this review, we briefly outlined the recent research progresses of endoplasmic reticulum-plasma membrane junctions in intracellular calcium homeostasis and cardiovascular disease, which may offer a new strategy for prevention and treatment of cardiovascular disease. PMID:27546511

  17. The Role of Endoplasmic Reticulum Stress and Unfolded Protein Response in Atherosclerosis

    PubMed Central

    Ivanova, Ekaterina A.; Orekhov, Alexander N.

    2016-01-01

    Pathogenesis of atherosclerosis is a complex process involving several metabolic and signalling pathways. Accumulating evidence demonstrates that endoplasmic reticulum stress and associated apoptosis can be induced in the pathological conditions of atherosclerotic lesions and contribute to the disease progression. Notably, they may play a role in the development of vulnerable plaques that induce thrombosis and are therefore especially dangerous. Endoplasmic reticulum stress response is regulated by several signaling mechanisms that involve protein kinases and transcription factors. Some of these molecules can be regarded as potential therapeutic targets to improve treatment of atherosclerosis. In this review we will discuss the role of endoplasmic reticulum stress and apoptosis in atherosclerosis development in different cell types and summarize the current knowledge on potential therapeutic agents targeting molecules regulating these pathways and their possible use for anti-atherosclerotic therapy. PMID:26840309

  18. Autophagic regulation of smooth muscle cell biology

    PubMed Central

    Salabei, Joshua K.; Hill, Bradford G.

    2014-01-01

    Autophagy regulates the metabolism, survival, and function of numerous cell types, including those comprising the cardiovascular system. In the vasculature, changes in autophagy have been documented in atherosclerotic and restenotic lesions and in hypertensive vessels. The biology of vascular smooth muscle cells appears particularly sensitive to changes in the autophagic program. Recent evidence indicates that stimuli or stressors evoked during the course of vascular disease can regulate autophagic activity, resulting in modulation of VSMC phenotype and viability. In particular, certain growth factors and cytokines, oxygen tension, and pharmacological drugs have been shown to trigger autophagy in smooth muscle cells. Importantly, each of these stimuli has a redox component, typically associated with changes in the abundance of reactive oxygen, nitrogen, or lipid species. Collective findings support the hypothesis that autophagy plays a critical role in vascular remodeling by regulating smooth muscle cell phenotype transitions and by influencing the cellular response to stress. In this graphical review, we summarize current knowledge on the role of autophagy in the biology of the smooth muscle cell in (patho)physiology. PMID:25544597

  19. Smooth PARAFAC Decomposition for Tensor Completion

    NASA Astrophysics Data System (ADS)

    Yokota, Tatsuya; Zhao, Qibin; Cichocki, Andrzej

    2016-10-01

    In recent years, low-rank based tensor completion, which is a higher-order extension of matrix completion, has received considerable attention. However, the low-rank assumption is not sufficient for the recovery of visual data, such as color and 3D images, where the ratio of missing data is extremely high. In this paper, we consider "smoothness" constraints as well as low-rank approximations, and propose an efficient algorithm for performing tensor completion that is particularly powerful regarding visual data. The proposed method admits significant advantages, owing to the integration of smooth PARAFAC decomposition for incomplete tensors and the efficient selection of models in order to minimize the tensor rank. Thus, our proposed method is termed as "smooth PARAFAC tensor completion (SPC)." In order to impose the smoothness constraints, we employ two strategies, total variation (SPC-TV) and quadratic variation (SPC-QV), and invoke the corresponding algorithms for model learning. Extensive experimental evaluations on both synthetic and real-world visual data illustrate the significant improvements of our method, in terms of both prediction performance and efficiency, compared with many state-of-the-art tensor completion methods.

  20. Autonomic Modification of Intestinal Smooth Muscle Contractility

    ERIC Educational Resources Information Center

    Montgomery, Laura E. A.; Tansey, Etain A.; Johnson, Chris D.; Roe, Sean M.; Quinn, Joe G.

    2016-01-01

    Intestinal smooth muscle contracts rhythmically in the absence of nerve and hormonal stimulation because of the activity of pacemaker cells between and within the muscle layers. This means that the autonomic nervous system modifies rather than initiates intestinal contractions. The practical described here gives students an opportunity to observe…

  1. Smoothing Methods for Estimating Test Score Distributions.

    ERIC Educational Resources Information Center

    Kolen, Michael J.

    1991-01-01

    Estimation/smoothing methods that are flexible enough to fit a wide variety of test score distributions are reviewed: kernel method, strong true-score model-based method, and method that uses polynomial log-linear models. Applications of these methods include describing/comparing test score distributions, estimating norms, and estimating…

  2. Smoothness and Striation in Digital Learning Spaces

    ERIC Educational Resources Information Center

    Bayne, Sian

    2004-01-01

    It is Deleuze & Guattari's description of smooth and striated cultural spaces (Deleuze & Guattari, 1988) which informs this exploration of pedagogical alternatives within the learning environments of cyberspace. Digital spaces work to constitute subject and text in ways which are distinct, and it is awareness of this distinctiveness which must…

  3. Cytochrome P450 system proteins reside in different regions of the endoplasmic reticulum.

    PubMed

    Park, Ji Won; Reed, James R; Brignac-Huber, Lauren M; Backes, Wayne L

    2014-12-01

    Cytochrome P450 (P450) function is dependent on the ability of these enzymes to successfully interact with their redox partners, NADPH-cytochrome P450 reductase (CPR) and cytochrome b5, in the endoplasmic reticulum (ER). Because the ER is heterogeneous in lipid composition, membrane microdomains with different characteristics are formed. Ordered microdomains are more tightly packed, and enriched in saturated fatty acids, sphingomyelin and cholesterol, whereas disordered regions contain higher levels of unsaturated fatty acids. The goal of the present study was to determine whether the P450 system proteins localize to different regions of the ER. The localization of CYP1A2, CYP2B4 and CYP2E1 within the ER was determined by partial membrane solubilization with Brij 98, centrifugation on a discontinuous sucrose gradient and immune blotting of the gradient fractions to identify ordered and disordered microdomains. CYP1A2 resided almost entirely in the ordered regions of the ER with CPR also localized predominantly to this region. CYP2B4 was equally distributed between the ordered and disordered domains. In contrast, CYP2E1 localized to the disordered membrane regions. Removal of cholesterol (an important constituent of ordered domains) led to the relocation of CYP1A2, CYP2B4 and CPR to the disordered regions. Interestingly, CYP1A1 and CYP1A2 localized to different membrane microdomains, despite their high degree of sequence similarity. These data demonstrate that P450 system enzymes are organized in specific membrane regions, and their localization can be affected by depletion of membrane cholesterol. The differential localization of different P450 in specific membrane regions may provide a novel mechanism for modulating P450 function. PMID:25236845

  4. Glycosylation is essential for translocation of carp retinol-binding protein across the endoplasmic reticulum membrane

    SciTech Connect

    Devirgiliis, Chiara; Gaetani, Sancia; Apreda, Marianna; Bellovino, Diana . E-mail: bellovino@inran.it

    2005-07-01

    Retinoid transport is well characterized in many vertebrates, while it is still largely unexplored in fish. To study the transport and utilization of vitamin A in these organisms, we have isolated from a carp liver cDNA library retinol-binding protein, its plasma carrier. The primary structure of carp retinol-binding protein is very conserved, but presents unique features compared to those of the correspondent proteins isolated and characterized so far in other species: it has an uncleavable signal peptide and two N-glycosylation sites in the NH{sub 2}-terminal region of the protein that are glycosylated in vivo. In this paper, we have investigated the function of the carbohydrate chains, by constructing three mutants deprived of the first, the second or both carbohydrates. The results of transient transfection of wild type and mutant retinol-binding protein in Cos cells followed by Western blotting and immunofluorescence analysis have shown that the absence of both carbohydrate moieties blocks secretion, while the presence of one carbohydrate group leads to an inefficient secretion. Experiments of carp RBP mRNA in vitro translation in a reticulocyte cell-free system in the presence of microsomes have demonstrated that N-glycosylation is necessary for efficient translocation across the endoplasmic reticulum membranes. Moreover, when Cos cells were transiently transfected with wild type and mutant retinol-binding protein (aa 1-67)-green fluorescent protein fusion constructs and semi-permeabilized with streptolysin O, immunofluorescence analysis with anti-green fluorescent protein antibody revealed that the double mutant is exposed to the cytosol, thus confirming the importance of glycan moieties in the translocation process.

  5. Indomethacin induces endoplasmic reticulum stress, but not apoptosis, in the rat kidney.

    PubMed

    Nagappan, Arumugam Suriyam; Varghese, Joe; James, Jithu V; Jacob, Molly

    2015-08-15

    Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in clinical practice. However, their use is often associated with adverse effects in the gastrointestinal tract and kidney. Our earlier work with indomethacin, a prototype NSAID, has shown that it induced oxidative stress in the kidney in rats, an event that has been postulated to contribute to pathogenesis of its adverse effects in this organ. Endoplasmic reticulum (ER) stress responses have been shown to occur in response to oxidative stress. We investigated whether this occurred in the rat kidney, in response to indomethacin. For this, Wistar rats were orally gavaged with indomethacin (20mg/kg). Markers of ER stress were studied in the kidneys 1, 12 and 24h later. GRP78, p-PERK and nuclear sXBP-1, all markers of ER stress, were found to be increased in the rat kidney at 12h, in response to indomethacin; levels of these markers fell by 24h. The effects seen at 12h were attenuated by pre-treatment with zinc, a known anti-oxidant, which has earlier been shown to ameliorate indomethacin-induced oxidative stress. Activation of an ER stress response was not associated with induction of apoptosis, as measured by markers of apoptosis such as release of cytochrome c from mitochondria into the cytosol, activation of caspases 3 and 9, cleavage of poly-ADP ribose polymerase and the presence of DNA laddering. We conclude that indomethacin-induced oxidative stress activated ER stress, but did not lead to apoptosis in the rat kidney.

  6. The endoplasmic reticulum stress response in aging and age-related diseases

    PubMed Central

    Brown, Marishka K.; Naidoo, Nirinjini

    2012-01-01

    The endoplasmic reticulum(ER) is a multifunctional organelle within which protein folding, lipid biosynthesis, and calcium storage occurs. Perturbations such as energy or nutrient depletion, disturbances in calcium or redox status that disrupt ER homeostasis lead to the misfolding of proteins, ER stress and up-regulation of several signaling pathways coordinately called the unfolded protein response (UPR). The UPR is characterized by the induction of chaperones, degradation of misfolded proteins and attenuation of protein translation. The UPR plays a fundamental role in the maintenance of cellular homeostasis and thus is central to normal physiology. However, sustained unresolved ER stress leads to apoptosis. Aging linked declines in expression and activity of key ER molecular chaperones and folding enzymes compromise proper protein folding and the adaptive response of the UPR. One mechanism to explain age associated declines in cellular functions and age-related diseases is a progressive failure of chaperoning systems. In many of these diseases, proteins or fragments of proteins convert from their normally soluble forms to insoluble fibrils or plaques that accumulate in a variety of organs including the liver, brain or spleen. This group of diseases, which typically occur late in life includes Alzheimer's, Parkinson's, type II diabetes and a host of less well known but often equally serious conditions such as fatal familial insomnia. The UPR is implicated in many of these neurodegenerative and familial protein folding diseases as well as several cancers and a host of inflammatory diseases including diabetes, atherosclerosis, inflammatory bowel disease and arthritis. This review will discuss age-related changes in the ER stress response and the role of the UPR in age-related diseases. PMID:22934019

  7. Endoplasmic reticulum chaperones are involved in the morphogenesis of rotavirus infectious particles.

    PubMed

    Maruri-Avidal, Liliana; López, Susana; Arias, Carlos F

    2008-06-01

    The final assembly of rotavirus particles takes place in the endoplasmic reticulum (ER). In this work, we evaluated by RNA interference the relevance to rotavirus assembly and infectivity of grp78, protein disulfide isomerase (PDI), grp94, calnexin, calreticulin, and ERp57, members of the two ER folding systems described herein. Silencing the expression of grp94 and Erp57 had no effect on rotavirus infectivity, while knocking down the expression of any of the other four chaperons caused a reduction in the yield of infectious virus of about 50%. In grp78-silenced cells, the maturation of the oligosaccharide chains of NSP4 was retarded. In cells with reduced levels of calnexin, the oxidative folding of VP7 was impaired and the trimming of NSP4 was accelerated, and in calreticulin-silenced cells, the formation of disulfide bonds of VP7 was also accelerated. The knockdown of PDI impaired the formation and/or rearrangement of the VP7 disulfide bonds. All these conditions also affected the correct assembly of virus particles, since compared with virions from control cells, they showed an altered susceptibility to EGTA and heat treatments, a decreased specific infectivity, and a diminished reactivity to VP7 with monoclonal antibody M60, which recognizes only this protein when its disulfide bonds have been correctly formed. In the case of grp78-silenced cells, the virus produced bound less efficiently to MA104 cells than virus obtained from control cells. All these results suggest that these chaperones are involved in the quality control of rotavirus morphogenesis. The complexity of the steps of rotavirus assembly that occur in the ER provide a useful model for studying the organization and operation of the complex network of chaperones involved in maintaining the quality control of this organelle.

  8. Vaccinia virus DNA replication occurs in endoplasmic reticulum-enclosed cytoplasmic mini-nuclei.

    PubMed

    Tolonen, N; Doglio, L; Schleich, S; Krijnse Locker, J

    2001-07-01

    Vaccinia virus (vv), a member of the poxvirus family, is unique among most DNA viruses in that its replication occurs in the cytoplasm of the infected host cell. Although this viral process is known to occur in distinct cytoplasmic sites, little is known about its organization and in particular its relation with cellular membranes. The present study shows by electron microscopy (EM) that soon after initial vv DNA synthesis at 2 h postinfection, the sites become entirely surrounded by membranes of the endoplasmic reticulum (ER). Complete wrapping requires ~45 min and persists until virion assembly is initiated at 6 h postinfection, and the ER dissociates from the replication sites. [(3)H]Thymidine incorporation at different infection times shows that efficient vv DNA synthesis coincides with complete ER wrapping, suggesting that the ER facilitates viral replication. Proteins known to be associated with the nuclear envelope in interphase cells are not targeted to these DNA-surrounding ER membranes, ruling out a role for these molecules in the wrapping process. By random green fluorescent protein-tagging of vv early genes of unknown function with a putative transmembrane domain, a novel vv protein, the gene product of E8R, was identified that is targeted to the ER around the DNA sites. Antibodies raised against this vv early membrane protein showed, by immunofluorescence microscopy, a characteristic ring-like pattern around the replication site. By electron microscopy quantitation the protein concentrated in the ER surrounding the DNA site and was preferentially targeted to membrane facing the inside of this site. These combined data are discussed in relation to nuclear envelope assembly/disassembly as it occurs during the cell cycle.

  9. Sequential NO production by mitochondria and endoplasmic reticulum during induced apoptosis.

    PubMed

    Bustamante, Juanita; Bersier, Geraldine; Badin, Romina Aron; Cymeryng, Cora; Parodi, Armando; Boveris, Alberto

    2002-05-01

    Early stages of rat thymocyte apoptosis measured as annexin-V positive events and induced by methylprednisolone (MPS), etoposide, and thapsigargin, showed a sequential increase in nitric oxide (NO) production by mitochondrial and endoplasmic reticulum membranes. Thapsigargin induced the highest NO production, a sevenfold increase as compared with untreated thymocytes, in mitochondrial and microsomal membranes. MPS and etoposide were equally effective in increasing NO production by mitochondrial membranes by a factor of 4-5, with only a slight increase in NO production by endoplasmic reticulum membranes. Western blot analysis of both types of membrane indicated that a nitric oxide synthase (NOS) isoenzyme is present in mitochondrial membranes and reacts with antibodies to i-NOS (type II), while reactivity to antibodies to e-NOS (type III) was restricted to endoplasmic reticulum. The participation of endoplasmic reticulum during apoptosis was further determined by alterations in UDP-Glucosyltransferase (UDP-GT) and NADPH cytochrome P450 reductase. Increased UDP-GT activity was observed after thapsigargin treatment, and no changes were found after treatment with etoposide or MPS. NADPH cytochrome P450 reductase activity markedly decreased during apoptosis, being stronger after thapsigargin treatment. The latest stage of the apoptotic process was measured by caspase activities. Caspase 3 activity was markedly increased by the three apoptosis inducers; caspase 6 was only activated by MPS and etoposide, while caspase 8 was not activated by any of these inducers. It is clear that mitochondria and endoplasmic reticulum are involved in thapsigargin induced thymocyte apoptosis. Meanwhile, other thymocyte apoptotic pathways, such as those induced by MPS or etoposide, seem to centrally involve mitochondria but not endoplasmic reticulum. PMID:12009851

  10. Sequential NO production by mitochondria and endoplasmic reticulum during induced apoptosis.

    PubMed

    Bustamante, Juanita; Bersier, Geraldine; Badin, Romina Aron; Cymeryng, Cora; Parodi, Armando; Boveris, Alberto

    2002-05-01

    Early stages of rat thymocyte apoptosis measured as annexin-V positive events and induced by methylprednisolone (MPS), etoposide, and thapsigargin, showed a sequential increase in nitric oxide (NO) production by mitochondrial and endoplasmic reticulum membranes. Thapsigargin induced the highest NO production, a sevenfold increase as compared with untreated thymocytes, in mitochondrial and microsomal membranes. MPS and etoposide were equally effective in increasing NO production by mitochondrial membranes by a factor of 4-5, with only a slight increase in NO production by endoplasmic reticulum membranes. Western blot analysis of both types of membrane indicated that a nitric oxide synthase (NOS) isoenzyme is present in mitochondrial membranes and reacts with antibodies to i-NOS (type II), while reactivity to antibodies to e-NOS (type III) was restricted to endoplasmic reticulum. The participation of endoplasmic reticulum during apoptosis was further determined by alterations in UDP-Glucosyltransferase (UDP-GT) and NADPH cytochrome P450 reductase. Increased UDP-GT activity was observed after thapsigargin treatment, and no changes were found after treatment with etoposide or MPS. NADPH cytochrome P450 reductase activity markedly decreased during apoptosis, being stronger after thapsigargin treatment. The latest stage of the apoptotic process was measured by caspase activities. Caspase 3 activity was markedly increased by the three apoptosis inducers; caspase 6 was only activated by MPS and etoposide, while caspase 8 was not activated by any of these inducers. It is clear that mitochondria and endoplasmic reticulum are involved in thapsigargin induced thymocyte apoptosis. Meanwhile, other thymocyte apoptotic pathways, such as those induced by MPS or etoposide, seem to centrally involve mitochondria but not endoplasmic reticulum.

  11. A sulfated polysaccharide from the sarcoplasmic reticulum of sea cucumber smooth muscle is an endogenous inhibitor of the Ca(2+)-ATPase.

    PubMed

    Landeira-Fernandez, A M; Aiello, K R; Aquino, R S; Silva, L C; Meis, L d; Mourão, P A

    2000-08-01

    Vesicles derived from the endoplasmic reticulum of sea cucumber smooth muscle retain a membrane bound Ca(2+)-ATPase that is able to transport Ca(2+) into the vesicles at the expense of ATP hydrolysis. In contrast with vesicles obtained from rabbit muscles, the activity of the Ca(2+)-dependent ATPase from sea cucumber is dependent on monovalent cations (K(+)>Na(+)>Li(+)). With the addition of highly sulfated polysaccharide to vesicle preparations from rabbit muscle, Ca(2+) uptake decreases sharply and becomes highly sensitive to monovalent cations, as observed with vesicles from sea cucumber muscle. These results led us to investigate the possible occurrence of a highly sulfated polysaccharide on vesicles from the endoplasmic reticulum of sea cucumber smooth muscle, acting as an "endogenous" Ca(2+)-ATPase inhibitor. In fact, vesicles derived from the invertebrate, but not from rabbit muscle, contain a highly sulfated polysaccharide. This compound inhibits Ca(2+) uptake in vesicles obtained from rabbit muscle and the inhibition is antagonized by monovalent cation. In addition, sea cucumber muscles contain high concentrations of another polysaccharide, which surrounds the muscle fibers, and was characterized as a fucosylated chondroitin sulfate. Possibly the occurrence of sulfated polysaccharides in the sea cucumber muscles is related with unique properties of the invertebrate body wall, which can rapidly and reversibly alter its mechanical properties, with change in length by more than 200%.

  12. The density of the cell sap and endoplasm of Nitellopsis and Chara

    NASA Technical Reports Server (NTRS)

    Wayne, R.; Staves, M. P.

    1991-01-01

    We measured the densities of the cell sap, endoplasm and cell wall of Nitellopsis obtusa and Chara corallina using interference microscopy, refractometry, immersion refractometry, equilibrium sedimentation and chemical microanalysis techniques. These values are important for the determination of many rheological properties of the cytoplasm as well as for understanding buoyancy regulation, dispersal mechanisms and how cells respond to gravity. The average densities of the cell sap, endoplasm and cell wall are 1,006.9, 1,016.7 and 1,371 kg m-3 for Nitellopsis and 1,005.0, 1,013.9, and 1,355.3 kg m-3 for Chara.

  13. Neuroprotective effects of atorvastatin against cerebral ischemia/reperfusion injury through the inhibition of endoplasmic reticulum stress.

    PubMed

    Yang, Jian-Wen; Hu, Zhi-Ping

    2015-08-01

    Cerebral ischemia triggers secondary ischemia/reperfusion injury and endoplasmic reticulum stress initiates cell apoptosis. However, the regulatory mechanism of the signaling pathway remains unclear. We hypothesize that the regulatory mechanisms are mediated by the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α in the endoplasmic reticulum stress signaling pathway. To verify this hypothesis, we occluded the middle cerebral artery in rats to establish focal cerebral ischemia/reperfusion model. Results showed that the expression levels of protein kinase-like endoplasmic reticulum kinase and caspase-3, as well as the phosphorylation of eukaryotic initiation factor 2α, were increased after ischemia/reperfusion. Administration of atorvastatin decreased the expression of protein kinase-like endoplasmic reticulum kinase, caspase-3 and phosphorylated eukaryotic initiation factor 2α, reduced the infarct volume and improved ultrastructure in the rat brain. After salubrinal, the specific inhibitor of phosphorylated eukaryotic initiation factor 2α was given into the rats intragastrically, the expression levels of caspase-3 and phosphorylated eukaryotic initiation factor 2α in the were decreased, a reduction of the infarct volume and less ultrastructural damage were observed than the untreated, ischemic brain. However, salubrinal had no impact on the expression of protein kinase-like endoplasmic reticulum kinase. Experimental findings indicate that atorvastatin inhibits endoplasmic reticulum stress and exerts neuroprotective effects. The underlying mechanisms of attenuating ischemia/reperfusion injury are associated with the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α/caspase-3 pathway. PMID:26487850

  14. Neuroprotective effects of atorvastatin against cerebral ischemia/reperfusion injury through the inhibition of endoplasmic reticulum stress

    PubMed Central

    Yang, Jian-wen; Hu, Zhi-ping

    2015-01-01

    Cerebral ischemia triggers secondary ischemia/reperfusion injury and endoplasmic reticulum stress initiates cell apoptosis. However, the regulatory mechanism of the signaling pathway remains unclear. We hypothesize that the regulatory mechanisms are mediated by the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α in the endoplasmic reticulum stress signaling pathway. To verify this hypothesis, we occluded the middle cerebral artery in rats to establish focal cerebral ischemia/reperfusion model. Results showed that the expression levels of protein kinase-like endoplasmic reticulum kinase and caspase-3, as well as the phosphorylation of eukaryotic initiation factor 2α, were increased after ischemia/reperfusion. Administration of atorvastatin decreased the expression of protein kinase-like endoplasmic reticulum kinase, caspase-3 and phosphorylated eukaryotic initiation factor 2α, reduced the infarct volume and improved ultrastructure in the rat brain. After salubrinal, the specific inhibitor of phosphorylated eukaryotic initiation factor 2α was given into the rats intragastrically, the expression levels of caspase-3 and phosphorylated eukaryotic initiation factor 2α in the were decreased, a reduction of the infarct volume and less ultrastructural damage were observed than the untreated, ischemic brain. However, salubrinal had no impact on the expression of protein kinase-like endoplasmic reticulum kinase. Experimental findings indicate that atorvastatin inhibits endoplasmic reticulum stress and exerts neuroprotective effects. The underlying mechanisms of attenuating ischemia/reperfusion injury are associated with the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α/caspase-3 pathway. PMID:26487850

  15. Transport of estradiol-17β-glucuronide, estrone-3-sulfate and taurocholate across the endoplasmic reticulum membrane: evidence for different transport systems.

    PubMed

    Wlcek, Katrin; Hofstetter, Lia; Stieger, Bruno

    2014-03-01

    Important reactions of drug metabolism, including UGT mediated glucuronidation and steroidsulfatase mediated hydrolysis of sulfates, take place in the endoplasmic reticulum (ER) of hepatocytes. Consequently, UGT generated glucuronides, like estradiol-17β-glucuronide, have to be translocated back into the cytoplasm to reach their site of excretion. Also steroidsulfatase substrates, including estrone-3-sulfate, have to cross the ER membrane to reach their site of hydrolysis. Based on their physicochemical properties such compounds are not favored for passive diffusion and therefore likely necessitate transport system(s) to cross the ER membrane in either direction. The current study aims to investigate the transport of taurocholate, estradiol-17β-glucuronide, and estrone-3-sulfate in smooth (SER) and rough (RER) endoplasmic reticulum membrane vesicles isolated from Wistar and TR(-) rat liver. Time-dependent and bidirectional transport was demonstrated for taurocholate, showing higher uptake rates in SER than RER vesicles. For estradiol-17β-glucuronide a fast time-dependent efflux with similar efficiencies from SER and RER but no clear protein-mediated uptake was shown, indicating an asymmetric transport system for this substrate. Estrone-3-sulfate uptake was time-dependent and higher in SER than in RER vesicles. Inhibition of steroidsulfatase mediated estrone-3-sulfate hydrolysis decreased estrone-3-sulfate uptake but had no effect on taurocholate or estradiol-17β-glucuronide transport. Based on inhibition studies and transport characteristics, three different transport mechanisms are suggested to be involved in the transport of taurocholate, estrone-3-sulfate and estradiol-17β-glucuronide across the ER membrane.

  16. Transport of estradiol-17β-glucuronide, estrone-3-sulfate and taurocholate across the endoplasmic reticulum membrane: evidence for different transport systems☆

    PubMed Central

    Wlcek, Katrin; Hofstetter, Lia; Stieger, Bruno

    2014-01-01

    Important reactions of drug metabolism, including UGT mediated glucuronidation and steroidsulfatase mediated hydrolysis of sulfates, take place in the endoplasmic reticulum (ER) of hepatocytes. Consequently, UGT generated glucuronides, like estradiol-17β-glucuronide, have to be translocated back into the cytoplasm to reach their site of excretion. Also steroidsulfatase substrates, including estrone-3-sulfate, have to cross the ER membrane to reach their site of hydrolysis. Based on their physicochemical properties such compounds are not favored for passive diffusion and therefore likely necessitate transport system(s) to cross the ER membrane in either direction. The current study aims to investigate the transport of taurocholate, estradiol-17β-glucuronide, and estrone-3-sulfate in smooth (SER) and rough (RER) endoplasmic reticulum membrane vesicles isolated from Wistar and TR− rat liver. Time-dependent and bidirectional transport was demonstrated for taurocholate, showing higher uptake rates in SER than RER vesicles. For estradiol-17β-glucuronide a fast time-dependent efflux with similar efficiencies from SER and RER but no clear protein-mediated uptake was shown, indicating an asymmetric transport system for this substrate. Estrone-3-sulfate uptake was time-dependent and higher in SER than in RER vesicles. Inhibition of steroidsulfatase mediated estrone-3-sulfate hydrolysis decreased estrone-3-sulfate uptake but had no effect on taurocholate or estradiol-17β-glucuronide transport. Based on inhibition studies and transport characteristics, three different transport mechanisms are suggested to be involved in the transport of taurocholate, estrone-3-sulfate and estradiol-17β-glucuronide across the ER membrane. PMID:24406246

  17. Effect of fluence smoothing on the quality of intensity-modulated radiation treatment plans.

    PubMed

    Niyas, Puzhakkal; Abdullah, Kallikuzhiyil Kochunny; Noufal, Manthala Padannayil; Sankaran Nair, Thekkedath

    2016-07-01

    A fluence-smoothing function applied for reducing the complexity of a treatment plan is an optional requirement in the inverse planning optimization algorithm of intensity-modulated radiation therapy (IMRT). In this study, we investigated the consequences of fluence smoothing on the quality of highly complex and inhomogeneous plans in a treatment-planning system, Eclipse™. The smoothing function was applied both in the direction of leaf travel (X) and perpendicular to leaf travel (Y). Twenty IMRT plans from patients with cancer of the nasopharynx and lung were selected and re-optimized with use of various smoothing combinations from X = 0, Y = 0 to X = 100, Y = 100. Total monitor units (MUs), dose-volume histograms, and radiobiological estimates were computed for all plans. The study yielded a significant reduction in the average total MUs from 2079 ± 265.4 to 1107 ± 137.4 (nasopharynx) and from 1556 ± 490.3 to 791 ± 176.8 (lung) while increasing smoothing from X, Y = 0 to X, Y = 100. Both the tumor control and normal tissue complication probabilities were found to vary, but not significantly so. No appreciable differences in doses to the target and most of the organs at risk (OARs) were noticed. The doses measured with the I'MRT MatriXX 2-D system indicated improvements in deliverability of the plans with higher smoothing values. Hence, it can be concluded that increased smoothing reduced the total MUs exceptionally well without any considerable changes in OAR doses. The observed progress in plan deliverability in terms of the gamma index strongly supports the recommendation of smoothing levels up to X = 70 and Y = 60, at least for the nasopharynx and lung. PMID:26951466

  18. Endoplasmic reticulum stress sensor protein kinase R-like endoplasmic reticulum kinase (PERK) protects against pressure overload-induced heart failure and lung remodeling.

    PubMed

    Liu, Xiaoyu; Kwak, Dongmin; Lu, Zhongbing; Xu, Xin; Fassett, John; Wang, Huan; Wei, Yidong; Cavener, Douglas R; Hu, Xinli; Hall, Jennifer; Bache, Robert J; Chen, Yingjie

    2014-10-01

    Studies have reported that development of congestive heart failure is associated with increased endoplasmic reticulum stress. Double stranded RNA-activated protein kinase R-like endoplasmic reticulum kinase (PERK) is a major transducer of the endoplasmic reticulum stress response and directly phosphorylates eukaryotic initiation factor 2α, resulting in translational attenuation. However, the physiological effect of PERK on congestive heart failure development is unknown. To study the effect of PERK on ventricular structure and function, we generated inducible cardiac-specific PERK knockout mice. Under unstressed conditions, cardiac PERK knockout had no effect on left ventricular mass, or its ratio to body weight, cardiomyocyte size, fibrosis, or left ventricular function. However, in response to chronic transverse aortic constriction, PERK knockout mice exhibited decreased ejection fraction, increased left ventricular fibrosis, enhanced cardiomyocyte apoptosis, and exacerbated lung remodeling in comparison with wild-type mice. PERK knockout also dramatically attenuated cardiac sarcoplasmic reticulum Ca(2+)-ATPase expression in response to aortic constriction. Our findings suggest that PERK is required to protect the heart from pressure overload-induced congestive heart failure.

  19. A novel inhibitor of advanced glycation and endoplasmic reticulum stress reduces infarct volume in rat focal cerebral ischemia.

    PubMed

    Takizawa, Shunya; Izuhara, Yuko; Kitao, Yasuko; Hori, Osamu; Ogawa, Satoshi; Morita, Yuko; Takagi, Shigeharu; van Ypersele de Strihou, Charles; Miyata, Toshio

    2007-12-01

    We have developed a novel, non-toxic inhibitor of advanced glycation and oxidative stress, TM2002, devoid of effect on blood pressure. In transient focal ischemia, TM2002 significantly decreased infarct volume compared with vehicle (79.5+/-18.7 vs. 183.3+/-22.9 mm3, p<0.01). In permanent focal ischemia, TM2002 (2.79, 5.58, and 11.16 mg/kg twice a day) dose-dependently reduced infarct volume (242.1+/-32.3, 201.3+/-15.1, and 171.3+/-15.2 mm3, respectively), and improved neurological deficits. Reduction of infarct volume is demonstrable, provided that TM2002 was administered within 1.5 h after the occlusion. To unravel TM2002's mechanism of action, we examined its in vitro effect on endoplasmic reticulum (ER) stress, using aortic smooth muscle cells isolated from ORP 150(+/-) mice and F9 Herp null mutated cells. Cell death induced by ER stress (tunicamycin or hypoxia) was dose-dependently prevented by TM2002. In vivo immunohistochemical study demonstrated a significant reduction of ORP- and TUNEL-positive apoptotic cells, especially in the penumbra. Inhibition of advanced glycation and oxidative stress was confirmed by a significantly reduced number of cells positive for advanced glycation end products and heme oxygenase-1. TM2002 reduced the levels of protein carbonyl formation in ischemic caudate. The efficacy of TM2002 is equivalent to that of a known neuroprotective agent, NXY-059. In conclusion, TM2002 significantly ameliorates ischemic cerebral damage through reduction of ER stress, advanced glycation, and oxidative stress, independently of blood pressure lowering.

  20. Inositol-requiring enzyme 1-mediated endoplasmic reticulum stress triggers apoptosis and fibrosis formation in liver cirrhosis rat models.

    PubMed

    Jiang, Tianpeng; Wang, Lizhou; Li, Xing; Song, Jie; Wu, Xiaoping; Zhou, Shi

    2015-04-01

    Long‑term and advanced cirrhosis is usually irreversible and often coincides with variceal hemorrhage or development of hepatocellular carcinoma; therefore, liver cirrhosis is a major cause of morbidity and mortality globally. The aim of the present study was to investigate the specific mechanism behind the formation of fibrosis or cirrhosis using rat models of hepatic fibrosis. The cirrhosis model was established by intraperitoneally administering dimethylnitrosamine to the rats. Hematoxylin and eosin staining was performed on the hepatic tissues of the rats to observe the fibrosis or cirrhosis, and western blot analysis was employed to detect α‑smooth muscle actin and desmin protein expression. Flow cytometric analysis was used to examine early and late apoptosis, and the protein and mRNA expression of endoplasmic reticulum (ER) stress-associated unfolded protein response (UPR) pathway proteins and apoptotic proteins [C/EBP homologous protein (CHOP) and caspase‑12] was detected by western blotting and the reverse-transcription polymerase chain reaction, respectively. The results indicated that the cirrhosis model was established successfully and that fibrosis was significantly increased in the cirrhosis model group compared with that in the normal control group. Flow cytometric analysis showed that early and late apoptosis in the cirrhosis model was significantly higher compared with that in the control group. The expression of the UPR pathway protein inositol-requiring enzyme (IRE) 1, as well as the expression of CHOP, was increased significantly in the cirrhotic rat tissues compared with that in the control group tissues (P<0.05). In conclusion, apoptosis was clearly observed in the hepatic tissue of cirrhotic rats, and the apoptosis was caused by activation of the ER stress-mediated IRE1 and CHOP.

  1. A Generalized Eigensolver based on Smoothed Aggregation (GES-SA) for Initializing Smoothed Aggregation Multigrid (SA)

    SciTech Connect

    Brezina, M; Manteuffel, T; McCormick, S; Ruge, J; Sanders, G; Vassilevski, P S

    2007-05-31

    Consider the linear system Ax = b, where A is a large, sparse, real, symmetric, and positive definite matrix and b is a known vector. Solving this system for unknown vector x using a smoothed aggregation multigrid (SA) algorithm requires a characterization of the algebraically smooth error, meaning error that is poorly attenuated by the algorithm's relaxation process. For relaxation processes that are typically used in practice, algebraically smooth error corresponds to the near-nullspace of A. Therefore, having a good approximation to a minimal eigenvector is useful to characterize the algebraically smooth error when forming a linear SA solver. This paper discusses the details of a generalized eigensolver based on smoothed aggregation (GES-SA) that is designed to produce an approximation to a minimal eigenvector of A. GES-SA might be very useful as a standalone eigensolver for applications that desire an approximate minimal eigenvector, but the primary aim here is for GES-SA to produce an initial algebraically smooth component that may be used to either create a black-box SA solver or initiate the adaptive SA ({alpha}SA) process.

  2. Compensating for estimation smoothing in kriging

    USGS Publications Warehouse

    Olea, R.A.; Pawlowsky, Vera

    1996-01-01

    Smoothing is a characteristic inherent to all minimum mean-square-error spatial estimators such as kriging. Cross-validation can be used to detect and model such smoothing. Inversion of the model produces a new estimator-compensated kriging. A numerical comparison based on an exhaustive permeability sampling of a 4-fr2 slab of Berea Sandstone shows that the estimation surface generated by compensated kriging has properties intermediate between those generated by ordinary kriging and stochastic realizations resulting from simulated annealing and sequential Gaussian simulation. The frequency distribution is well reproduced by the compensated kriging surface, which also approximates the experimental semivariogram well - better than ordinary kriging, but not as well as stochastic realizations. Compensated kriging produces surfaces that are more accurate than stochastic realizations, but not as accurate as ordinary kriging. ?? 1996 International Association for Mathematical Geology.

  3. Tribological properties of smooth diamond films

    NASA Astrophysics Data System (ADS)

    Pimenov, S. M.; Smolin, A. A.; Obraztsova, E. D.; Konov, V. I.; Bögli, U.; Blatter, A.; Loubnin, E. N.; Maillat, M.; Leijala, A.; Burger, J.; Hintermann, H. E.

    1996-02-01

    The friction and wear properties of smooth diamond coatings sliding against a monocrystalline ruby ball were studied using a pin-on-disk tribometer. The smooth diamond film surface was prepared either by (i) deposition of ultrathin nanocrystalline films in the thickness range from 0.2 to 2 μm or by (ii) postgrowth polishing. Excimer laser surface ablation, microwave plasma etching and mechanical lapping with diamond grit were used for postgrowth polishing. A correlation of film surface properties examined with different techniques (atomic force microscopy, Auger electron spectroscopy, Raman spectroscopy, stylus profilometry) and the tribological properties of the diamond films tested was established. The influence of laser-induced surface graphitization on the friction coefficient of laser-polished films was investigated.

  4. SPHGR: Smoothed-Particle Hydrodynamics Galaxy Reduction

    NASA Astrophysics Data System (ADS)

    Thompson, Robert

    2015-02-01

    SPHGR (Smoothed-Particle Hydrodynamics Galaxy Reduction) is a python based open-source framework for analyzing smoothed-particle hydrodynamic simulations. Its basic form can run a baryonic group finder to identify galaxies and a halo finder to identify dark matter halos; it can also assign said galaxies to their respective halos, calculate halo & galaxy global properties, and iterate through previous time steps to identify the most-massive progenitors of each halo and galaxy. Data about each individual halo and galaxy is collated and easy to access. SPHGR supports a wide range of simulations types including N-body, full cosmological volumes, and zoom-in runs. Support for multiple SPH code outputs is provided by pyGadgetReader (ascl:1411.001), mainly Gadget (ascl:0003.001) and TIPSY (ascl:1111.015).

  5. Variational algorithms for nonlinear smoothing applications

    NASA Technical Reports Server (NTRS)

    Bach, R. E., Jr.

    1977-01-01

    A variational approach is presented for solving a nonlinear, fixed-interval smoothing problem with application to offline processing of noisy data for trajectory reconstruction and parameter estimation. The nonlinear problem is solved as a sequence of linear two-point boundary value problems. Second-order convergence properties are demonstrated. Algorithms for both continuous and discrete versions of the problem are given, and example solutions are provided.

  6. Structure-Preserving Smoothing of Biomedical Images

    NASA Astrophysics Data System (ADS)

    Gil, Debora; Hernàndez-Sabaté, Aura; Burnat, Mireia; Jansen, Steven; Martínez-Villalta, Jordi

    Smoothing of biomedical images should preserve gray-level transitions between adjacent tissues, while restoring contours consistent with anatomical structures. Anisotropic diffusion operators are based on image appearance discontinuities (either local or contextual) and might fail at weak inter-tissue transitions. Meanwhile, the output of block-wise and morphological operations is prone to present a block structure due to the shape and size of the considered pixel neighborhood.

  7. On the thermodynamics of smooth muscle contraction

    NASA Astrophysics Data System (ADS)

    Stålhand, Jonas; McMeeking, Robert M.; Holzapfel, Gerhard A.

    2016-09-01

    Cell function is based on many dynamically complex networks of interacting biochemical reactions. Enzymes may increase the rate of only those reactions that are thermodynamically consistent. In this paper we specifically treat the contraction of smooth muscle cells from the continuum thermodynamics point of view by considering them as an open system where matter passes through the cell membrane. We systematically set up a well-known four-state kinetic model for the cross-bridge interaction of actin and myosin in smooth muscle, where the transition between each state is driven by forward and reverse reactions. Chemical, mechanical and energy balance laws are provided in local forms, while energy balance is also formulated in the more convenient temperature form. We derive the local (non-negative) production of entropy from which we deduce the reduced entropy inequality and the constitutive equations for the first Piola-Kirchhoff stress tensor, the heat flux, the ion and molecular flux and the entropy. One example for smooth muscle contraction is analyzed in more detail in order to provide orientation within the established general thermodynamic framework. In particular the stress evolution, heat generation, muscle shorting rate and a condition for muscle cooling are derived.

  8. Smooth muscle tumours of the alimentary tract.

    PubMed Central

    Diamond, T.; Danton, M. H.; Parks, T. G.

    1990-01-01

    Neoplasms arising from smooth muscle of the gastrointestinal (GI) tract are uncommon, comprising only 1% of gastrointestinal tumours. A total of 51 cases of smooth muscle tumour of the GI tract were analysed; 44 leiomyomas and 7 leiomyosarcomas. Lesions occurred in all areas from the oesophagus to the rectum, the stomach being the commonest site. Thirty-six patients had clinical features referable to the tumour. The tumour was detected during investigation or management of an unrelated disease process in 15 patients. The clinical presentation varied depending on tumour location, but abdominal pain and GI bleeding were the commonest presenting symptoms. The lesion was demonstrated preoperatively, mainly by endoscopy and barium studies, in 27 patients. Surgical excision was the treatment of choice, where possible. There was no recurrence in the leiomyoma group but four patients died in the leiomyosarcoma group. Although rare, smooth muscle tumours should be considered in situations where clinical presentation and investigations are not suggestive of any common GI disorder. The preoperative assessment and diagnosis is difficult because of the variability in clinical features and their inaccessibility to routine GI investigation. It is recommended that, where possible, the lesion, whether symptomatic or discovered incidentally, should be excised completely to achieve a cure and prevent future complications. Images Figure 3 Figure 4 PMID:2221768

  9. Chlorhexidine-induced apoptosis or necrosis in L929 fibroblasts: A role for endoplasmic reticulum stress

    SciTech Connect

    Faria, Gisele; Cardoso, Cristina R.B.; Larson, Roy E.; Silva, Joao S.; Rossi, Marcos A.

    2009-01-15

    Chlorhexidine (CHX), widely used as antiseptic and therapeutic agent in medicine and dentistry, has a toxic effect both in vivo and in vitro. The intrinsic mechanism underlying CHX-induced cytotoxicity in eukaryotic cells is, however, still unknown. A recent study from our laboratory has suggested that CHX may induce death in cultured L929 fibroblasts via endoplasmic reticulum (ER) stress. This hypothesis was further tested by means of light and electron microscopy, quantification of apoptosis and necrosis by flow cytometry, fluorescence visualization of the cytoskeleton and endoplasmic reticulum, and evaluation of the expression of 78-kDa glucose-regulated protein 78 (Grp78), a marker of activation of the unfolded protein response (UPR) in cultured L929 fibroblasts. Our finding showing increased Grp 78 expression in CHX-treated cells and the results of flow cytometry, cytoskeleton and endoplasmic reticulum fluorescence visualization, and scanning and transmission electron microscopy allowed us to suggest that CHX elicits accumulation of proteins in the endoplasmic reticulum, which causes ER overload, resulting in ER stress and cell death either by necrosis or apoptosis. It must be pointed out, however, that this does not necessarily mean that ER stress is the only way that CHX kills L929 fibroblasts, but rather that ER stress is an important target or indicator of cell death induced by this drug.

  10. The unit membrane, the endoplasmic reticulum, and the nuclear pores are artefacts.

    PubMed

    Hillman, H; Sartory, P

    1977-01-01

    It is shown on the basis of solid geometry that the trilaminar appearance of membranes described by Robertson must be an artefact, although the membranes themselves are not. However, considerations of solid geometry as well as observations on living cells indicate that the endoplasmic reticulum and nuclear pores are artefacts resulting from preparation for electron microscopy. Suggestions for their genesis are proposed.

  11. Modulation of active Ca2+ uptake by the islet-cell endoplasmic reticulum.

    PubMed Central

    Colca, J R; Kotagal, N; Lacy, P E; McDaniel, M L

    1983-01-01

    The possible effects of calmodulin and cyclic AMP on active Ca2+ uptake by the islet-cell endoplasmic reticulum were investigated. Neither calmodulin nor cyclic AMP affected the rate of active Ca2+ uptake, or the steady-state filling capacity of the endoplasmic reticulum when measured in the absence of oxalate. Consistent with these results, calmodulin did not activate the Ca2+-stimulated ATPase activity associated with this cell fraction. During the course of these experiments., it was unexpectedly discovered that the rate of Ca2+ uptake, as well as the steady-state Ca2+ filling capacity of the endoplasmic reticulum, were markedly increased by unidentified factor(s) in the cytosol. This effect could be demonstrated by reconstitution of the membranes in cytosol, or by direct addition of fresh or dialysed cytosol to the Ca2+ uptake assays. The degree of activation by the cytosol indicates that the endoplasmic reticulum may play a prominent role in controlling beta-cell Ca2+ concentrations and that the unidentified activator(s) present in the cytosol may be involved in regulation of this function. PMID:6307286

  12. Contractile properties of isolated vascular smooth muscle after photoradiation

    SciTech Connect

    Freas, W.; Hart, J.L.; Golightly, D.; McClure, H.; Muldoon, S.M.

    1989-03-01

    The purpose of this study was to characterize the responses of various types of vascular smooth muscle to conditions that would be encountered during photodynamic therapy, namely laser illumination of photosensitizer-pretreated tissue. Vascular smooth muscle obtained from representative canine, rodent, and rabbit vascular beds was cut into rings and placed in organ baths (37 degrees C, aerated with 95% O2-5% CO2). These vessels were pretreated for 30 min with the photosensitizer hematoporphyrin derivative (HpD, 3-30 micrograms/ml) washed, and then exposed to red laser light (633 nm, 1-3.5 mW) for up to 20 min. Under basal tension conditions laser illumination of HpD-pretreated vessels resulted in an increase in tension, whereas laser illumination of vessels not exposed to HpD did not contract. This sustained contraction was not reversed by washing the tissue with fresh Krebs-Ringer solution. Responses to norepinephrine, transmural electrical stimulation, and elevated concentrations of KCl were reduced in blood vessels tested after HpD laser illumination. Laser-induced contractions of canine carotid arteries did not require the presence of an intact vascular endothelium. Vascular effect of these photosensitizers appears to involve the formation of oxygen-derived radicals. This preparation could provide a good model for examining the effects of free radicals on vascular physiology.

  13. Oxidized low density lipoprotein (LDL) affects hyaluronan synthesis in human aortic smooth muscle cells.

    PubMed

    Viola, Manuela; Bartolini, Barbara; Vigetti, Davide; Karousou, Evgenia; Moretto, Paola; Deleonibus, Sara; Sawamura, Tatsuya; Wight, Thomas N; Hascall, Vincent C; De Luca, Giancarlo; Passi, Alberto

    2013-10-11

    Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20-50 μg/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 μg/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 μg/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL.

  14. Oxidized Low Density Lipoprotein (LDL) Affects Hyaluronan Synthesis in Human Aortic Smooth Muscle Cells*

    PubMed Central

    Viola, Manuela; Bartolini, Barbara; Vigetti, Davide; Karousou, Evgenia; Moretto, Paola; Deleonibus, Sara; Sawamura, Tatsuya; Wight, Thomas N.; Hascall, Vincent C.; De Luca, Giancarlo; Passi, Alberto

    2013-01-01

    Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20–50 μg/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 μg/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 μg/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL. PMID:23979132

  15. 7 CFR 51.772 - Fairly smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Definitions § 51.772 Fairly smooth texture. Fairly smooth texture means that the skin is fairly thin and not coarse for the variety and size of the fruit. “Fairly thin” means that the skin thickness does...

  16. A model for the generation of localized transient [Na{sup +}] elevations in vascular smooth muscle

    SciTech Connect

    Fameli, Nicola; Kuo, Kuo-Hsing; Breemen, Cornelis van

    2009-11-20

    We present a stochastic computational model to study the mechanism of signaling between a source and a target ionic transporter, both localized on the plasma membrane (PM). In general this requires a nanometer-scale cytoplasmic space, or nanodomain, between the PM and a peripheral organelle to reflect ions back towards the PM. Specifically we investigate the coupling between Na{sup +} entry via the transient receptor potential canonical channel 6 (TRPC6) and the Na{sup +}/Ca{sup 2+} exchanger (NCX), a process which is essential for reloading the sarcoplasmic reticulum (SR) via the sarco/endoplasmic reticulum Ca{sup 2+}ATPase (SERCA) and maintaining Ca{sup 2+} oscillations in activated vascular smooth muscle. Having previously modeled the flow of Ca{sup 2+} between reverse NCX and SERCA during SR refilling, this quantitative approach now allows us to model the upstream linkage of Na{sup +} entry through TRPC6 to reversal of NCX. We have implemented a random walk (RW) Monte Carlo (MC) model with simulations mimicking a diffusion process originating at the TRPC6 within PM-SR junctions. The model calculates the average Na{sup +} in the nanospace and also produces profiles as a function of distance from the source. Our results highlight the necessity of a strategic juxtaposition of the relevant ion translocators as well as other physical structures within the nanospaces to permit adequate Na{sup +} build-up to initiate NCX reversal and Ca{sup 2+} influx to refill the SR.

  17. Autophagy plays a protective role in free cholesterol overload-induced death of smooth muscle cells.

    PubMed

    Xu, Kedi; Yang, Yi; Yan, Ming; Zhan, Jianan; Fu, Xiao; Zheng, Xiaoxiang

    2010-09-01

    Smooth muscle cells (SMC) make up most of the vascular system. In advanced atherosclerotic plaques, dying SMCs undergo a complex death mode. In the present study, we examined the activation of autophagy in SMCs overloaded with excess free cholesterol (FC) and investigated the possible role which autophagy plays during the FC-induced cell death. After incubation with excess FC, a robust expression of autophagic vacuoles (AV) was detected using both fluorescence microscopy and transmission electron microscopy (TEM). The results revealed that FC induced a time-dependent upregulation of microtubule-associated protein-1 light chain 3-II (LC3-II). Inhibition of autophagy by 3-methyladenine (3-MA) enhanced both cell apoptosis and necrosis, while on the contrary, rapamycin inhibited cell death following cholesterol application. Furthermore, the impact of the colocalization of fragmented mitochondria with AVs was observed after cholesterol treatment. Our results also revealed that the modulation of autophagy directly influenced the cellular organellar stress. In conclusion, our findings demonstrated that excess FC induced the activation of autophagy in SMCs as a cellular defense mechanism, possibly through the degradation of dysfunctional organelles such as mitochondria and endoplasmic reticulum. PMID:20484746

  18. Isolation and functional characterization of Sporothrix schenckii ROT2, the encoding gene for the endoplasmic reticulum glucosidase II.

    PubMed

    Robledo-Ortiz, Claudia I; Flores-Carreón, Arturo; Hernández-Cervantes, Arturo; Álvarez-Vargas, Aurelio; Lee, Keunsook K; Díaz-Jiménez, Diana F; Munro, Carol A; Cano-Canchola, Carmen; Mora-Montes, Héctor M

    2012-08-01

    The N-linked glycosylation is a ubiquitous protein modification in eukaryotic cells. During the N-linked glycan synthesis, the precursor Glc(3)Man(9)GlcNAc(2) is processed by endoplasmic reticulum (ER) glucosidases I, II and α1,2-mannosidase, before transporting to the Golgi complex for further structure modifications. In fungi of medical relevance, as Candida albicans and Aspergillus, it is well known that ER glycosidases are important for cell fitness, cell wall organization, virulence, and interaction with the immune system. Despite this, little is known about these enzymes in Sporothrix schenckii, the causative agent of human sporotrichosis. This limited knowledge is due in part to the lack of a genome sequence of this organism. In this work we used degenerate primers and inverse PCR approaches to isolate the open reading frame of S. schenckii ROT2, the encoding gene for α subunit of ER glucosidase II. This S. schenckii gene complemented a Saccharomyces cerevisiae rot2Δ mutant; however, when expressed in a C. albicans rot2Δ mutant, S. schenckii Rot2 partially increased the levels of α-glucosidase activity, but failed to restore the N-linked glycosylation defect associated to the mutation. To our knowledge, this is the first report where a gene involved in protein N-linked glycosylation is isolated from S. schenckii.

  19. The Candida albicans Kar2 protein is essential and functions during the translocation of proteins into the endoplasmic reticulum

    PubMed Central

    Janke, Megan R.; Lund, Kyle; Morrison, Emily P.; Paulson, Benjamin A.

    2012-01-01

    Since the secretory pathway is essential for Candida albicans to transition from a commensal organism to a pathogen, an understanding of how this pathway functions may be beneficial for identifying novel drug targets to prevent candidiasis. We have cloned the C. albicans KAR2 gene, which performs many roles during the translocation of proteins into the endoplasmic reticulum (ER) during the first committed step of the secretory pathway in many eukaryotes. Our results show that C. albicans KAR2 is essential, and that the encoded protein rescues a temperature-sensitive growth defect found in a Saccharomyces cerevisiae strain harboring a mutant form of the Kar2 protein. Additionally, S. cerevisiae containing CaKAR2 as the sole copy of this essential gene are viable, and ER microsomes prepared from this strain exhibit wild-type levels of post-translational translocation during in vitro translocation assays. Finally, ER microsomes isolated from a C. albicans strain expressing reduced amounts of KAR2 mRNA are defective for in vitro translocation of a secreted substrate protein, establishing a new method to study ER translocation in this organism. Together, these results suggest that C. albicans Kar2p functions during the translocation of proteins into the ER during the first step of the secretory pathway. PMID:20886215

  20. Polarized endoplasmic reticulum aggregations in the establishing division plane of protodermal cells of the fern Asplenium nidus.

    PubMed

    Giannoutsou, E; Sotiriou, P; Apostolakos, P; Galatis, B

    2015-01-01

    The determination of the division plane in protodermal cells of the fern Asplenium nidus occurs during interphase with the formation of the phragmosome, the organization of which is controlled by the actomyosin system. Usually, the phragmosomes between adjacent cells were oriented on the same plane. In the phragmosomal cortical cytoplasm, an interphase microtubule (MT) ring was formed and large quantities of endoplasmic reticulum (ER) membranes were gathered, forming an interphase U-like ER bundle. During preprophase/prophase, the interphase MT ring and the U-like ER bundle were transformed into a MT and an ER preprophase band (PPB), respectively. Parts of the ER-PPB were maintained during mitosis. Furthermore, the plasmalemma as well as the nuclear envelope displayed local polarization on the phragmosome plane, while the cytoplasm between them was occupied by distinct ER aggregations. These consistent findings suggest that Α. nidus protodermal cells constitute a unique system in which three elements of the endomembrane system (ER, plasmalemma, and nuclear envelope) show specific characteristics in the establishing division plane. Our experimental data support that the organization of the U-like ER bundle is controlled on a cellular level by the actomyosin system and intercellularly by factors emitted from the leaf apex. The possible role of the above endomembrane system elements on the mechanism that coordinates the determination of the division plane between adjacent cells in protodermal tissue of A. nidus is discussed. PMID:24972554

  1. Infant Attention and the Development of Smooth Pursuit Tracking.

    ERIC Educational Resources Information Center

    Richards, John E.; Holley, Felecia B.

    1999-01-01

    Studied effect of attention on smooth pursuit and saccadic tracking in infants at 8, 14, 20, and 26 weeks old. Found an increase across age in overall tracking, gain of smooth-pursuit eye movements, and increased amplitude of compensatory saccades at faster tracking speeds. Findings show that development of smooth pursuit, targeted saccadic eye…

  2. 7 CFR 51.1162 - Fairly smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly smooth texture. 51.1162 Section 51.1162 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... smooth texture. Fairly smooth texture means that the skin is fairly thin and not coarse for the...

  3. 7 CFR 51.1008 - Fairly smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth texture. 51.1008 Section 51.1008... STANDARDS) United States Standards for Persian (Tahiti) Limes Definitions § 51.1008 Fairly smooth texture. Fairly smooth texture means that the fruit is comparatively free from lumpiness and that pebbling is...

  4. 7 CFR 51.1162 - Fairly smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fairly smooth texture. 51.1162 Section 51.1162 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... Definitions § 51.1162 Fairly smooth texture. Fairly smooth texture means that the skin is fairly thin and...

  5. 7 CFR 51.772 - Fairly smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth texture. 51.772 Section 51.772... STANDARDS) United States Standards for Grades of Florida Grapefruit Definitions § 51.772 Fairly smooth texture. Fairly smooth texture means that the skin is fairly thin and not coarse for the variety and...

  6. 7 CFR 51.1162 - Fairly smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth texture. 51.1162 Section 51.1162 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... smooth texture. Fairly smooth texture means that the skin is fairly thin and not coarse for the...

  7. 7 CFR 51.641 - Fairly smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth texture. 51.641 Section 51.641 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards..., and Arizona) Definitions § 51.641 Fairly smooth texture. Fairly smooth texture means that the skin...

  8. 7 CFR 51.1008 - Fairly smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly smooth texture. 51.1008 Section 51.1008... STANDARDS) United States Standards for Persian (Tahiti) Limes Definitions § 51.1008 Fairly smooth texture. Fairly smooth texture means that the fruit is comparatively free from lumpiness and that pebbling is...

  9. 7 CFR 51.641 - Fairly smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth texture. 51.641 Section 51.641 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards..., and Arizona) Definitions § 51.641 Fairly smooth texture. Fairly smooth texture means that the skin...

  10. Neurophysiology and Neuroanatomy of Smooth Pursuit in Humans

    ERIC Educational Resources Information Center

    Lencer, Rebekka; Trillenberg, Peter

    2008-01-01

    Smooth pursuit eye movements enable us to focus our eyes on moving objects by utilizing well-established mechanisms of visual motion processing, sensorimotor transformation and cognition. Novel smooth pursuit tasks and quantitative measurement techniques can help unravel the different smooth pursuit components and complex neural systems involved…

  11. 7 CFR 51.1008 - Fairly smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Fairly smooth texture. 51.1008 Section 51.1008 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards....1008 Fairly smooth texture. Fairly smooth texture means that the fruit is comparatively free...

  12. 7 CFR 51.1162 - Fairly smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth texture. 51.1162 Section 51.1162 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... smooth texture. Fairly smooth texture means that the skin is fairly thin and not coarse for the...

  13. 7 CFR 51.701 - Fairly smooth texture.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Fairly smooth texture. 51.701 Section 51.701 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards..., and Arizona) Definitions § 51.701 Fairly smooth texture. Fairly smooth texture means that the skin...

  14. 7 CFR 51.772 - Fairly smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth texture. 51.772 Section 51.772... STANDARDS) United States Standards for Grades of Florida Grapefruit Definitions § 51.772 Fairly smooth texture. Fairly smooth texture means that the skin is fairly thin and not coarse for the variety and...

  15. 7 CFR 51.641 - Fairly smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly smooth texture. 51.641 Section 51.641 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards..., and Arizona) Definitions § 51.641 Fairly smooth texture. Fairly smooth texture means that the skin...

  16. 7 CFR 51.1162 - Fairly smooth texture.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Fairly smooth texture. 51.1162 Section 51.1162 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... Definitions § 51.1162 Fairly smooth texture. Fairly smooth texture means that the skin is fairly thin and...

  17. 7 CFR 51.701 - Fairly smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth texture. 51.701 Section 51.701 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards..., and Arizona) Definitions § 51.701 Fairly smooth texture. Fairly smooth texture means that the skin...

  18. 7 CFR 51.772 - Fairly smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fairly smooth texture. 51.772 Section 51.772 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... Definitions § 51.772 Fairly smooth texture. Fairly smooth texture means that the skin is fairly thin and...

  19. 7 CFR 51.1008 - Fairly smooth texture.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Fairly smooth texture. 51.1008 Section 51.1008 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards....1008 Fairly smooth texture. Fairly smooth texture means that the fruit is comparatively free...

  20. 7 CFR 51.701 - Fairly smooth texture.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly smooth texture. 51.701 Section 51.701 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards..., and Arizona) Definitions § 51.701 Fairly smooth texture. Fairly smooth texture means that the skin...

  1. 7 CFR 51.1008 - Fairly smooth texture.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Fairly smooth texture. 51.1008 Section 51.1008... STANDARDS) United States Standards for Persian (Tahiti) Limes Definitions § 51.1008 Fairly smooth texture. Fairly smooth texture means that the fruit is comparatively free from lumpiness and that pebbling is...

  2. Visual Short-Term Memory During Smooth Pursuit Eye Movements

    ERIC Educational Resources Information Center

    Kerzel, Dirk; Ziegler, Nathalie E.

    2005-01-01

    Visual short-term memory (VSTM) was probed while observers performed smooth pursuit eye movements. Smooth pursuit keeps a moving object stabilized in the fovea. VSTM capacity for position was reduced during smooth pursuit compared with a condition with eye fixation. There was no difference between a condition in which the items were approximately…

  3. Alternative Smoothing and Scaling Strategies for Weighted Composite Scores

    ERIC Educational Resources Information Center

    Moses, Tim

    2014-01-01

    In this study, smoothing and scaling approaches are compared for estimating subscore-to-composite scaling results involving composites computed as rounded and weighted combinations of subscores. The considered smoothing and scaling approaches included those based on raw data, on smoothing the bivariate distribution of the subscores, on smoothing…

  4. Post-growth surface smoothing of thin films of diindenoperylene

    SciTech Connect

    Hinderhofer, A.; Hosokai, T.; Yonezawa, K.; Kato, K.; Kera, S.; Ueno, N.; Gerlach, A.; Broch, K.; Frank, C.; Schreiber, F.; Novak, J.

    2012-07-16

    We applied in situ x-ray reflectivity and ultraviolet photoelectron spectroscopy to study the impact of annealing on low temperature (200 K) deposited organic thin films of diindenoperylene (DIP) on SiO{sub 2} and indium tin oxide (ITO). At 200 K, DIP is crystalline on SiO{sub 2} and amorphous on ITO. Upon heating to room temperature, the roughness of DIP is reduced on both substrates, from 1.5 nm to 0.75 nm (SiO{sub 2}) and from 0.90 nm to 0.45 nm (ITO). The smoothing is accompanied by crystallization of the surface molecules, whereas the bulk structure of the films does not strongly reorganize.

  5. Overexpression of Smooth Muscle Myosin Heavy Chain Leads to Activation of the Unfolded Protein Response and Autophagic Turnover of Thick Filament-associated Proteins in Vascular Smooth Muscle Cells*

    PubMed Central

    Kwartler, Callie S.; Chen, Jiyuan; Thakur, Dhananjay; Li, Shumin; Baskin, Kedryn; Wang, Shanzhi; Wang, Zhao V.; Walker, Lori; Hill, Joseph A.; Epstein, Henry F.; Taegtmeyer, Heinrich; Milewicz, Dianna M.

    2014-01-01

    Duplications spanning nine genes at the genomic locus 16p13.1 predispose individuals to acute aortic dissections. The most likely candidate gene in this region leading to the predisposition for dissection is MYH11, which encodes smooth muscle myosin heavy chain (SM-MHC). The effects of increased expression of MYH11 on smooth muscle cell (SMC) phenotypes were explored using mouse aortic SMCs with transgenic overexpression of one isoform of SM-MHC. We found that these cells show increased expression of Myh11 and myosin filament-associated contractile genes at the message level when compared with control SMCs, but not at the protein level due to increased protein degradation. Increased expression of Myh11 resulted in endoplasmic reticulum (ER) stress in SMCs, which led to a paradoxical decrease of protein levels through increased autophagic degradation. An additional consequence of ER stress in SMCs was increased intracellular calcium ion concentration, resulting in increased contractile signaling and contraction. The increased signals for contraction further promote transcription of contractile genes, leading to a feedback loop of metabolic abnormalities in these SMCs. We suggest that overexpression of MYH11 can lead to increased ER stress and autophagy, findings that may be globally implicated in disease processes associated with genomic duplications. PMID:24711452

  6. A comparison of intrinsic endoplasmic reticulum membrane proteins in maturing seeds and germinated seedlings of castor bean.

    PubMed

    Goldberg, D B; Al-Marayati, S; González, E

    1982-01-01

    The intrinsic membrane proteins of the endoplasmic reticulum from endosperm of maturing and germinated seedlings of castor bean (Ricinus communis) were studied. Preparations were simultaneously subjected to two-dimensional polyacrylamide gel electrophoresis. At least 30 separate proteins were distinguished by staining the gels with Coomassie R-250. The characteristic protein profiles obtained from 0.2 m KCl-washed membranes of each endoplasmic reticulum source are highly reproducible. Of these proteins, three to six that were present in maturing seed were found also in germinating seedlings. In general, the majority of membrane proteins from the endoplasmic reticulum of maturing seed were of a higher molecular weight than those from germinated seedlings.

  7. Compressive Sensing via Nonlocal Smoothed Rank Function.

    PubMed

    Fan, Ya-Ru; Huang, Ting-Zhu; Liu, Jun; Zhao, Xi-Le

    2016-01-01

    Compressive sensing (CS) theory asserts that we can reconstruct signals and images with only a small number of samples or measurements. Recent works exploiting the nonlocal similarity have led to better results in various CS studies. To better exploit the nonlocal similarity, in this paper, we propose a non-convex smoothed rank function based model for CS image reconstruction. We also propose an efficient alternating minimization method to solve the proposed model, which reduces a difficult and coupled problem to two tractable subproblems. Experimental results have shown that the proposed method performs better than several existing state-of-the-art CS methods for image reconstruction. PMID:27583683

  8. Method for producing smooth inner surfaces

    DOEpatents

    Cooper, Charles A.

    2016-05-17

    The invention provides a method for preparing superconducting cavities, the method comprising causing polishing media to tumble by centrifugal barrel polishing within the cavities for a time sufficient to attain a surface smoothness of less than 15 nm root mean square roughness over approximately a 1 mm.sup.2 scan area. The method also provides for a method for preparing superconducting cavities, the method comprising causing polishing media bound to a carrier to tumble within the cavities. The method also provides for a method for preparing superconducting cavities, the method comprising causing polishing media in a slurry to tumble within the cavities.

  9. On spaces of functions of smoothness zero

    SciTech Connect

    Besov, Oleg V

    2012-08-31

    The paper is concerned with the new spaces B-bar{sub p,q}{sup 0} of functions of smoothness zero defined on the n-dimensional Euclidean space R{sup n} or on a subdomain G of R{sup n}. These spaces are compared with the spaces B{sub p,q}{sup 0}(R{sup n}) and bmo(R{sup n}). The embedding theorems for Sobolev spaces are refined in terms of the space B-bar{sub p,q}{sup 0} with the limiting exponent. Bibliography: 8 titles.

  10. Impact modeling with Smooth Particle Hydrodynamics

    SciTech Connect

    Stellingwerf, R.F.; Wingate, C.A.

    1993-07-01

    Smooth Particle Hydrodynamics (SPH) can be used to model hypervelocity impact phenomena via the addition of a strength of materials treatment. SPH is the only technique that can model such problems efficiently due to the combination of 3-dimensional geometry, large translations of material, large deformations, and large void fractions for most problems of interest. This makes SPH an ideal candidate for modeling of asteroid impact, spacecraft shield modeling, and planetary accretion. In this paper we describe the derivation of the strength equations in SPH, show several basic code tests, and present several impact test cases with experimental comparisons.

  11. Workshop on advances in smooth particle hydrodynamics

    SciTech Connect

    Wingate, C.A.; Miller, W.A.

    1993-12-31

    This proceedings contains viewgraphs presented at the 1993 workshop held at Los Alamos National Laboratory. Discussed topics include: negative stress, reactive flow calculations, interface problems, boundaries and interfaces, energy conservation in viscous flows, linked penetration calculations, stability and consistency of the SPH method, instabilities, wall heating and conservative smoothing, tensors, tidal disruption of stars, breaking the 10,000,000 particle limit, modelling relativistic collapse, SPH without H, relativistic KSPH avoidance of velocity based kernels, tidal compression and disruption of stars near a supermassive rotation black hole, and finally relativistic SPH viscosity and energy.

  12. Mutator Dynamics on a Smooth Evolutionary Landscape

    NASA Astrophysics Data System (ADS)

    Kessler, David A.; Levine, Herbert

    1998-03-01

    We investigate a model of evolutionary dynamics on a smooth landscape which features a ``mutator'' allele which increases the mutation rate. We show that when the fitness is far from its equilibrium value the expected proportion of mutators approaches a value governed solely by the transition rates into and out of the mutator state, resulting in a much faster fitness increase than would be the case without the mutator allele. Near the fitness equilibrium, the mutators are severely suppressed, due to the detrimental effects of a large mutation rate near the fitness maximum. We discuss the results of a recent experiment on natural selection of E. coli in the light of our model.

  13. Accurate statistical tests for smooth classification images.

    PubMed

    Chauvin, Alan; Worsley, Keith J; Schyns, Philippe G; Arguin, Martin; Gosselin, Frédéric

    2005-10-05

    Despite an obvious demand for a variety of statistical tests adapted to classification images, few have been proposed. We argue that two statistical tests based on random field theory (RFT) satisfy this need for smooth classification images. We illustrate these tests on classification images representative of the literature from F. Gosselin and P. G. Schyns (2001) and from A. B. Sekuler, C. M. Gaspar, J. M. Gold, and P. J. Bennett (2004). The necessary computations are performed using the Stat4Ci Matlab toolbox.

  14. Compressive Sensing via Nonlocal Smoothed Rank Function

    PubMed Central

    Fan, Ya-Ru; Liu, Jun; Zhao, Xi-Le

    2016-01-01

    Compressive sensing (CS) theory asserts that we can reconstruct signals and images with only a small number of samples or measurements. Recent works exploiting the nonlocal similarity have led to better results in various CS studies. To better exploit the nonlocal similarity, in this paper, we propose a non-convex smoothed rank function based model for CS image reconstruction. We also propose an efficient alternating minimization method to solve the proposed model, which reduces a difficult and coupled problem to two tractable subproblems. Experimental results have shown that the proposed method performs better than several existing state-of-the-art CS methods for image reconstruction. PMID:27583683

  15. Compressive Sensing via Nonlocal Smoothed Rank Function.

    PubMed

    Fan, Ya-Ru; Huang, Ting-Zhu; Liu, Jun; Zhao, Xi-Le

    2016-01-01

    Compressive sensing (CS) theory asserts that we can reconstruct signals and images with only a small number of samples or measurements. Recent works exploiting the nonlocal similarity have led to better results in various CS studies. To better exploit the nonlocal similarity, in this paper, we propose a non-convex smoothed rank function based model for CS image reconstruction. We also propose an efficient alternating minimization method to solve the proposed model, which reduces a difficult and coupled problem to two tractable subproblems. Experimental results have shown that the proposed method performs better than several existing state-of-the-art CS methods for image reconstruction.

  16. Traffic of Human α-Mannosidase in Plant Cells Suggests the Presence of a New Endoplasmic Reticulum-to-Vacuole Pathway without Involving the Golgi Complex1[W

    PubMed Central

    De Marchis, Francesca; Bellucci, Michele; Pompa, Andrea

    2013-01-01

    The transport of secretory proteins from the endoplasmic reticulum to the vacuole requires sorting signals as well as specific transport mechanisms. This work is focused on the transport in transgenic tobacco (Nicotiana tabacum) plants of a human α-mannosidase, MAN2B1, which is a lysosomal enzyme involved in the turnover of N-linked glycoproteins and can be used in enzyme replacement therapy. Although ubiquitously expressed, α-mannosidases are targeted to lysosomes or vacuoles through different mechanisms according to the organisms in which these proteins are produced. In tobacco cells, MAN2B1 reaches the vacuole even in the absence of mannose-6-phosphate receptors, which are responsible for its transport in animal cells. We report that MAN2B1 is targeted to the vacuole without passing through the Golgi complex. In addition, a vacuolar targeting signal that is recognized in plant cells is located in the MAN2B1 amino-terminal region. Indeed, when this amino-terminal domain is removed, the protein is retained in the endoplasmic reticulum. Moreover, when this domain is added to a plant-secreted protein, the resulting fusion protein is partially redirected to the vacuole. These results strongly suggest the existence in plants of a new type of vacuolar traffic that can be used by leaf cells to transport vacuolar proteins. PMID:23449646

  17. Traffic of human α-mannosidase in plant cells suggests the presence of a new endoplasmic reticulum-to-vacuole pathway without involving the Golgi complex.

    PubMed

    De Marchis, Francesca; Bellucci, Michele; Pompa, Andrea

    2013-04-01

    The transport of secretory proteins from the endoplasmic reticulum to the vacuole requires sorting signals as well as specific transport mechanisms. This work is focused on the transport in transgenic tobacco (Nicotiana tabacum) plants of a human α-mannosidase, MAN2B1, which is a lysosomal enzyme involved in the turnover of N-linked glycoproteins and can be used in enzyme replacement therapy. Although ubiquitously expressed, α-mannosidases are targeted to lysosomes or vacuoles through different mechanisms according to the organisms in which these proteins are produced. In tobacco cells, MAN2B1 reaches the vacuole even in the absence of mannose-6-phosphate receptors, which are responsible for its transport in animal cells. We report that MAN2B1 is targeted to the vacuole without passing through the Golgi complex. In addition, a vacuolar targeting signal that is recognized in plant cells is located in the MAN2B1 amino-terminal region. Indeed, when this amino-terminal domain is removed, the protein is retained in the endoplasmic reticulum. Moreover, when this domain is added to a plant-secreted protein, the resulting fusion protein is partially redirected to the vacuole. These results strongly suggest the existence in plants of a new type of vacuolar traffic that can be used by leaf cells to transport vacuolar proteins.

  18. Improved beam smoothing with SSD using generalized phase modulation

    SciTech Connect

    Rothenberg, J.E.

    1997-01-01

    The smoothing of the spatial illumination of an inertial confinement fusion target is examined by its spatial frequency content. It is found that the smoothing by spectral dispersion method, although efficient for glass lasers, can yield poor smoothing at low spatial frequency. The dependence of the smoothed spatial spectrum on the characteristics of phase modulation and dispersion is examined for both sinusoidal and more general phase modulation. It is shown that smoothing with non-sinusoidal phase modulation can result in spatial spectra which are substantially identical to that obtained with the induced spatial incoherence or similar method where random phase plates are present in both methods and identical beam divergence is assumed.

  19. Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders

    PubMed Central

    Brozovich, F.V.; Nicholson, C.J.; Degen, C.V.; Gao, Yuan Z.; Aggarwal, M.

    2016-01-01

    The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function. PMID:27037223

  20. Polychlorinated biphenyl quinone induces endoplasmic reticulum stress, unfolded protein response, and calcium release.

    PubMed

    Xu, Demei; Su, Chuanyang; Song, Xiufang; Shi, Qiong; Fu, Juanli; Hu, Lihua; Xia, Xiaomin; Song, Erqun; Song, Yang

    2015-06-15

    Organisms are able to respond to environmental insult to maintain cellular homeostasis, which include the activation of a wide range of cellular adaptive responses with tightly controlled mechanisms. The endoplasmic reticulum (ER) is an organelle responsible for protein folding and calcium storage. ER stress leads to the accumulation of unfolded proteins in the ER lumen. To be against or respond to this effect, cells have a comprehensive signaling system, called unfolded protein response (UPR), to restore homeostasis and normal ER function or activate the cell death program. Therefore, it is critical to understand how environmental insult regulates the ingredients of ER stress and UPR signalings. Previously, we have demonstrated that polychlorinated biphenyl (PCB) quinone caused oxidative stress, cytotoxicity, genotoxicity, and apoptosis in HepG2 cells. Here, we investigated the role of a PCB quinone, PCB29-pQ on ER stress, UPR, and calcium release. PCB29-pQ markedly increased the hallmark genes of ER stress, namely, glucose-regulated protein 78 (GRP78), GRP94, and C/EBP homologous protein (CHOP) on both protein and mRNA levels in HepG2 cells. We also confirmed PCB29-pQ induced ER morphological defects by using transmission electron microscopy. Moreover, PCB29-pQ induced intracellular calcium accumulation and calpain activity, which were significantly inhibited by the pretreatment of BAPTA-AM (Ca(2+) chelator). These results were correlated with the outcome that PCB29-pQ induces ER stress-related apoptosis through caspase family gene 12, while salubrinal and Z-ATAD-FMK (a specific inhibitor of caspase 12) partially ameliorated this effect, respectively. N-Acetyl-l-cysteine (NAC) scavenged ROS formation and consequently alleviated PCB29-pQ-induced expression of ER stress-related genes. In conclusion, our result demonstrated for the first time that PCB quinone leads to ROS-dependent induction of ER stress, and UPR and calcium release in HepG2 cells, and the

  1. Cortex phellodendri Extract Relaxes Airway Smooth Muscle

    PubMed Central

    Jiang, Qiu-Ju; Chen, Weiwei; Dan, Hong; Tan, Li; Zhu, He; Yang, Guangzhong; Shen, Jinhua; Peng, Yong-Bo; Zhao, Ping; Xue, Lu; Yu, Meng-Fei; Ma, Liqun; Si, Xiao-Tang; Wang, Zhuo; Dai, Jiapei; Qin, Gangjian; Zou, Chunbin; Liu, Qing-Hua

    2016-01-01

    Cortex phellodendri is used to reduce fever and remove dampness and toxin. Berberine is an active ingredient of C. phellodendri. Berberine from Argemone ochroleuca can relax airway smooth muscle (ASM); however, whether the nonberberine component of C. phellodendri has similar relaxant action was unclear. An n-butyl alcohol extract of C. phellodendri (NBAECP, nonberberine component) was prepared, which completely inhibits high K+- and acetylcholine- (ACH-) induced precontraction of airway smooth muscle in tracheal rings and lung slices from control and asthmatic mice, respectively. The contraction induced by high K+ was also blocked by nifedipine, a selective blocker of L-type Ca2+ channels. The ACH-induced contraction was partially inhibited by nifedipine and pyrazole 3, an inhibitor of TRPC3 and STIM/Orai channels. Taken together, our data demonstrate that NBAECP can relax ASM by inhibiting L-type Ca2+ channels and TRPC3 and/or STIM/Orai channels, suggesting that NBAECP could be developed to a new drug for relieving bronchospasm. PMID:27239213

  2. Cortex phellodendri Extract Relaxes Airway Smooth Muscle.

    PubMed

    Jiang, Qiu-Ju; Chen, Weiwei; Dan, Hong; Tan, Li; Zhu, He; Yang, Guangzhong; Shen, Jinhua; Peng, Yong-Bo; Zhao, Ping; Xue, Lu; Yu, Meng-Fei; Ma, Liqun; Si, Xiao-Tang; Wang, Zhuo; Dai, Jiapei; Qin, Gangjian; Zou, Chunbin; Liu, Qing-Hua

    2016-01-01

    Cortex phellodendri is used to reduce fever and remove dampness and toxin. Berberine is an active ingredient of C. phellodendri. Berberine from Argemone ochroleuca can relax airway smooth muscle (ASM); however, whether the nonberberine component of C. phellodendri has similar relaxant action was unclear. An n-butyl alcohol extract of C. phellodendri (NBAECP, nonberberine component) was prepared, which completely inhibits high K(+)- and acetylcholine- (ACH-) induced precontraction of airway smooth muscle in tracheal rings and lung slices from control and asthmatic mice, respectively. The contraction induced by high K(+) was also blocked by nifedipine, a selective blocker of L-type Ca(2+) channels. The ACH-induced contraction was partially inhibited by nifedipine and pyrazole 3, an inhibitor of TRPC3 and STIM/Orai channels. Taken together, our data demonstrate that NBAECP can relax ASM by inhibiting L-type Ca(2+) channels and TRPC3 and/or STIM/Orai channels, suggesting that NBAECP could be developed to a new drug for relieving bronchospasm.

  3. Isotropic Growth of Graphene toward Smoothing Stitching.

    PubMed

    Zeng, Mengqi; Tan, Lifang; Wang, Lingxiang; Mendes, Rafael G; Qin, Zhihui; Huang, Yaxin; Zhang, Tao; Fang, Liwen; Zhang, Yanfeng; Yue, Shuanglin; Rümmeli, Mark H; Peng, Lianmao; Liu, Zhongfan; Chen, Shengli; Fu, Lei

    2016-07-26

    The quality of graphene grown via chemical vapor deposition still has very great disparity with its theoretical property due to the inevitable formation of grain boundaries. The design of single-crystal substrate with an anisotropic twofold symmetry for the unidirectional alignment of graphene seeds would be a promising way for eliminating the grain boundaries at the wafer scale. However, such a delicate process will be easily terminated by the obstruction of defects or impurities. Here we investigated the isotropic growth behavior of graphene single crystals via melting the growth substrate to obtain an amorphous isotropic surface, which will not offer any specific grain orientation induction or preponderant growth rate toward a certain direction in the graphene growth process. The as-obtained graphene grains are isotropically round with mixed edges that exhibit high activity. The orientation of adjacent grains can be easily self-adjusted to smoothly match each other over a liquid catalyst with facile atom delocalization due to the low rotation steric hindrance of the isotropic grains, thus achieving the smoothing stitching of the adjacent graphene. Therefore, the adverse effects of grain boundaries will be eliminated and the excellent transport performance of graphene will be more guaranteed. What is more, such an isotropic growth mode can be extended to other types of layered nanomaterials such as hexagonal boron nitride and transition metal chalcogenides for obtaining large-size intrinsic film with low defect. PMID:27403842

  4. Smooth blasting with the electronic delay detonator

    SciTech Connect

    Yamamoto, Masaaki; Ichijo, Toshiyuki; Tanaka, Yoshiharu

    1995-12-31

    The authors utilized electronic detonators (EDs) to investigate the effect of high detonator delay accuracy on overbreak, remaining rock damage, and surface smoothness, in comparison with that of long-period delay detonators (0.25 sec interval) PDs. The experiments were conducted in a deep mine, in a test site region composed of very hard granodiorite with a seismic wave velocity of about 6.0 km/sec and a uniaxial compressive strength, uniaxial tensile strength, and Young`s modulus of 300 MPa, 12 MPa, and 73 GPa, respectively. The blasting design was for a test tunnel excavation of 8 m{sup 2} in cross section, with an advance per round of 2.5 m. Five rounds were performed, each with a large-hole cut and perimeter holes in a 0.4-m spacing charged with 20-mm-diameter water gel explosive to obtain low charge concentration. EDs were used in the holes on the perimeter of the right half, and PDs were used in all other holes. Following each shot, the cross section was measured by laser to determine amount of overbreak and surface smoothness. In situ seismic prospecting was used to estimate the depth of damage in the remaining rock, and the damage was further investigated by boring into both side walls.

  5. Cortex phellodendri Extract Relaxes Airway Smooth Muscle.

    PubMed

    Jiang, Qiu-Ju; Chen, Weiwei; Dan, Hong; Tan, Li; Zhu, He; Yang, Guangzhong; Shen, Jinhua; Peng, Yong-Bo; Zhao, Ping; Xue, Lu; Yu, Meng-Fei; Ma, Liqun; Si, Xiao-Tang; Wang, Zhuo; Dai, Jiapei; Qin, Gangjian; Zou, Chunbin; Liu, Qing-Hua

    2016-01-01

    Cortex phellodendri is used to reduce fever and remove dampness and toxin. Berberine is an active ingredient of C. phellodendri. Berberine from Argemone ochroleuca can relax airway smooth muscle (ASM); however, whether the nonberberine component of C. phellodendri has similar relaxant action was unclear. An n-butyl alcohol extract of C. phellodendri (NBAECP, nonberberine component) was prepared, which completely inhibits high K(+)- and acetylcholine- (ACH-) induced precontraction of airway smooth muscle in tracheal rings and lung slices from control and asthmatic mice, respectively. The contraction induced by high K(+) was also blocked by nifedipine, a selective blocker of L-type Ca(2+) channels. The ACH-induced contraction was partially inhibited by nifedipine and pyrazole 3, an inhibitor of TRPC3 and STIM/Orai channels. Taken together, our data demonstrate that NBAECP can relax ASM by inhibiting L-type Ca(2+) channels and TRPC3 and/or STIM/Orai channels, suggesting that NBAECP could be developed to a new drug for relieving bronchospasm. PMID:27239213

  6. Isotropic Growth of Graphene toward Smoothing Stitching.

    PubMed

    Zeng, Mengqi; Tan, Lifang; Wang, Lingxiang; Mendes, Rafael G; Qin, Zhihui; Huang, Yaxin; Zhang, Tao; Fang, Liwen; Zhang, Yanfeng; Yue, Shuanglin; Rümmeli, Mark H; Peng, Lianmao; Liu, Zhongfan; Chen, Shengli; Fu, Lei

    2016-07-26

    The quality of graphene grown via chemical vapor deposition still has very great disparity with its theoretical property due to the inevitable formation of grain boundaries. The design of single-crystal substrate with an anisotropic twofold symmetry for the unidirectional alignment of graphene seeds would be a promising way for eliminating the grain boundaries at the wafer scale. However, such a delicate process will be easily terminated by the obstruction of defects or impurities. Here we investigated the isotropic growth behavior of graphene single crystals via melting the growth substrate to obtain an amorphous isotropic surface, which will not offer any specific grain orientation induction or preponderant growth rate toward a certain direction in the graphene growth process. The as-obtained graphene grains are isotropically round with mixed edges that exhibit high activity. The orientation of adjacent grains can be easily self-adjusted to smoothly match each other over a liquid catalyst with facile atom delocalization due to the low rotation steric hindrance of the isotropic grains, thus achieving the smoothing stitching of the adjacent graphene. Therefore, the adverse effects of grain boundaries will be eliminated and the excellent transport performance of graphene will be more guaranteed. What is more, such an isotropic growth mode can be extended to other types of layered nanomaterials such as hexagonal boron nitride and transition metal chalcogenides for obtaining large-size intrinsic film with low defect.

  7. Ultrastructure of the intercalated body, a novel organelle associated with fluid forming cells in the organ of Corti.

    PubMed

    Sobkowicz, H M; Holy, J; Scott, G L

    1990-07-01

    The intercalated body is a newly discovered organelle in the inner and outer spiral sulcus cells of the mouse organ of Corti. The organelle was found in the cochleas of 14-day and older intact mice and in organs in culture of corresponding ages. The organelle consists of a stack of interconnected cisternae of endoplasmic reticulum and of membrane bound rodlets that are intercalated between, and run parallel to, the cisternae. The cisternal membranes are predominantly smooth, but some may display ribosomes. Most rodlets are from 1 to 2 microns long, about 0.1 micron wide, and contain electron dense material. Mitochondria are commonly associated with or incorporated into the organelle. Some electron micrographs suggest that the rodlets may originate from modified mitochondria. It is our impression that the formation of the organelle begins with the apposition of cisternae and mitochondria. Cisternal-associated mitochondria appear to constrict, elongate, and lose their inner membranes. In both the intact animal and in culture, the cells of the inner and outer spiral sulci display microvilli, apical junctional complexes, lateral intercellular spaces containing interdigitating cell processes, and appear to be involved in fluid formation. Moreover, in culture, the cells of inner and outer spiral sulci as well as some cells proliferating in the outgrowth zone participate in fluid formation, producing large fluid pockets. All these cells commonly contain intercalated bodies. It is possible that in the intact animal, as in culture, intercalated bodies may play a role in fluid regulation in the immediate vicinity of the hair cells.

  8. Modeling of toxin-antibody interaction and toxin transport toward the endoplasmic reticulum.

    PubMed

    Skakauskas, Vladas; Katauskis, Pranas

    2016-01-01

    A model for toxin-antibody interaction and toxin trafficking towards the endoplasmic-reticulum is presented. Antibody and toxin (ricin) initially are delivered outside the cell. The model involves: the pinocytotic (cellular drinking) and receptor-mediated toxin internalization modes from the extracellular into the intracellular domain, its exocytotic excretion from the cytosol back to the extracellular medium, the intact toxin retrograde transport to the endoplasmic reticulum, the anterograde toxin movement outward from the cell across the plasma membrane, the lysosomal toxin degradation, and the toxin clearance (removal from the system) flux. The model consists of a set of coupled PDEs. Using an averaging procedure, the model is reduced to a system of coupled ODEs. Both PDEs and ODEs systems are solved numerically. Numerical results are illustrated by figures and discussed.

  9. Protein accumulation in the endoplasmic reticulum as a non-equilibrium phase transition.

    PubMed

    Budrikis, Zoe; Costantini, Giulio; La Porta, Caterina A M; Zapperi, Stefano

    2014-01-01

    Several neurological disorders are associated with the aggregation of aberrant proteins, often localized in intracellular organelles such as the endoplasmic reticulum. Here we study protein aggregation kinetics by mean-field reactions and three dimensional Monte carlo simulations of diffusion-limited aggregation of linear polymers in a confined space, representing the endoplasmic reticulum. By tuning the rates of protein production and degradation, we show that the system undergoes a non-equilibrium phase transition from a physiological phase with little or no polymer accumulation to a pathological phase characterized by persistent polymerization. A combination of external factors accumulating during the lifetime of a patient can thus slightly modify the phase transition control parameters, tipping the balance from a long symptomless lag phase to an accelerated pathological development. The model can be successfully used to interpret experimental data on amyloid-β clearance from the central nervous system. PMID:24722051

  10. Protein accumulation in the endoplasmic reticulum as a non-equilibrium phase transition

    PubMed Central

    Budrikis, Zoe; Costantini, Giulio; La Porta, Caterina A. M.; Zapperi, Stefano

    2014-01-01

    Several neurological disorders are associated with the aggregation of aberrant proteins, often localized in intracellular organelles such as the endoplasmic reticulum. Here we study protein aggregation kinetics by mean-field reactions and three dimensional Monte carlo simulations of diffusion-limited aggregation of linear polymers in a confined space, representing the endoplasmic reticulum. By tuning the rates of protein production and degradation, we show that the system undergoes a non-equilibrium phase transition from a physiological phase with little or no polymer accumulation to a pathological phase characterized by persistent polymerization. A combination of external factors accumulating during the lifetime of a patient can thus slightly modify the phase transition control parameters, tipping the balance from a long symptomless lag phase to an accelerated pathological development. The model can be successfully used to interpret experimental data on amyloid-β clearance from the central nervous system. PMID:24722051

  11. Transport of cholesterol from the endoplasmic reticulum to the plasma membrane

    PubMed Central

    1985-01-01

    We have studied the transport of newly synthesized cholesterol from the endoplasmic reticulum to the plasma membrane in Chinese hamster ovary cells using a cell fractionation assay. We found that transport is dependent on metabolic energy, but that the maintenance of the high differential concentration of cholesterol in the plasma membrane is not an energy-requiring process. We have tested a variety of inhibitors for their effect on cholesterol transport and found that cytochalasin B, colchicine, monensin, cycloheximide, and NH4Cl did not have any effect. The cholesterol transport process shows a sharp temperature dependence; it ceases at 15 degrees C, whereas cholesterol synthesis continues. When synthesis occurs at 15 degrees C, the newly synthesized cholesterol accumulates in the endoplasmic reticulum and in a low density, lipid-rich vesicle fraction. These results suggest that cholesterol is transported via a vesicular system. PMID:4040520

  12. Advanced oxidation protein products induce endothelial-to-mesenchymal transition in human renal glomerular endothelial cells through induction of endoplasmic reticulum stress.

    PubMed

    Liang, Xiujie; Duan, Na; Wang, Yue; Shu, Shuangshuang; Xiang, Xiaohong; Guo, Tingting; Yang, Lei; Zhang, Shaojie; Tang, Xun; Zhang, Jun

    2016-01-01

    Endothelial-to-mesenchymal transition (EndMT) in renal glomerular endothelial cells plays a critical role in the pathogenesis of diabetic nephropathy (DN). Furthermore, advanced oxidation protein products (AOPPs) have been shown to contribute to the progression of DN. However, whether AOPPs induce EndMT in renal glomerular endothelial cells remains unclear. Thus, we investigated the effect of AOPPs on human renal glomerular endothelial cells (HRGECs) and the mechanisms underlying the effects. Our results showed that AOPP treatment lowered the expression of vascular endothelial cadherin, CD31, and claudin 5 and induced the overexpression of α-smooth muscle actin, vimentin, and fibroblast-specific protein 1, which indicated that AOPPs induced EndMT in HRGECs. Furthermore, AOPP stimulation increased the expression of glucose-regulated protein 78 and CCAAT/enhancer-binding protein-homologous protein, which suggested that AOPPs triggered endoplasmic reticulum (ER) stress in HRGECs. Notably, the aforementioned AOPP effects were reversed following the treatment of cells with salubrinal, an inhibitor of ER stress, whereas the effects were reproduced after exposure to thapsigargin, an inducer of ER stress. Collectively, our results indicate that AOPPs trigger EndMT in HRGECs through the induction of ER stress. These findings suggest novel therapeutic strategies for inhibiting renal fibrosis by targeting ER stress.

  13. Advanced oxidation protein products induce endothelial-to-mesenchymal transition in human renal glomerular endothelial cells through induction of endoplasmic reticulum stress.

    PubMed

    Liang, Xiujie; Duan, Na; Wang, Yue; Shu, Shuangshuang; Xiang, Xiaohong; Guo, Tingting; Yang, Lei; Zhang, Shaojie; Tang, Xun; Zhang, Jun

    2016-01-01

    Endothelial-to-mesenchymal transition (EndMT) in renal glomerular endothelial cells plays a critical role in the pathogenesis of diabetic nephropathy (DN). Furthermore, advanced oxidation protein products (AOPPs) have been shown to contribute to the progression of DN. However, whether AOPPs induce EndMT in renal glomerular endothelial cells remains unclear. Thus, we investigated the effect of AOPPs on human renal glomerular endothelial cells (HRGECs) and the mechanisms underlying the effects. Our results showed that AOPP treatment lowered the expression of vascular endothelial cadherin, CD31, and claudin 5 and induced the overexpression of α-smooth muscle actin, vimentin, and fibroblast-specific protein 1, which indicated that AOPPs induced EndMT in HRGECs. Furthermore, AOPP stimulation increased the expression of glucose-regulated protein 78 and CCAAT/enhancer-binding protein-homologous protein, which suggested that AOPPs triggered endoplasmic reticulum (ER) stress in HRGECs. Notably, the aforementioned AOPP effects were reversed following the treatment of cells with salubrinal, an inhibitor of ER stress, whereas the effects were reproduced after exposure to thapsigargin, an inducer of ER stress. Collectively, our results indicate that AOPPs trigger EndMT in HRGECs through the induction of ER stress. These findings suggest novel therapeutic strategies for inhibiting renal fibrosis by targeting ER stress. PMID:26861949

  14. Assessing the contribution of thrombospondin-4 induction and ATF6α activation to endoplasmic reticulum expansion and phenotypic modulation in bladder outlet obstruction

    PubMed Central

    Krawczyk, Katarzyna K.; Ekman, Mari; Rippe, Catarina; Grossi, Mario; Nilsson, Bengt-Olof; Albinsson, Sebastian; Uvelius, Bengt; Swärd, Karl

    2016-01-01

    Phenotypic modulation of smooth muscle cells is a hallmark of disease. The associated expansion of endoplasmic reticulum (ER) volume remains unexplained. Thrombospondin-4 was recently found to promote ATF6α activation leading to ER expansion. Using bladder outlet obstruction as a paradigm for phenotypic modulation, we tested if thrombospondin-4 is induced in association with ATF6α activation and ER expansion. Thrombospondin-4 was induced and ATF6α was activated after outlet obstruction in rodents. Increased abundance of spliced of Xbp1, another ER-stress sensor, and induction of Atf4 and Creb3l2 was also seen. Downstream of ATF6α, Calr, Manf, Sdf2l1 and Pdi increased as did ER size, whereas contractile markers were reduced. Overexpression of ATF6α, but not of thrombospondin-4, increased Calr, Manf, Sdf2l1 and Pdi and caused ER expansion, but the contractile markers were inert. Knockout of thrombospondin-4 neither affected bladder growth nor expression of ATF6α target genes, and repression of contractile markers was the same, even if ATF6α activation was curtailed. Increases of Xbp1s, Atf4 and Creb3l2 were similar. Our findings demonstrate reciprocal regulation of the unfolded protein response, including ATF6α activation and ER expansion, and reduced contractile differentiation in bladder outlet obstruction occurring independently of thrombospondin-4, which however is a sensitive indicator of obstruction. PMID:27581066

  15. Assessing the contribution of thrombospondin-4 induction and ATF6α activation to endoplasmic reticulum expansion and phenotypic modulation in bladder outlet obstruction.

    PubMed

    Krawczyk, Katarzyna K; Ekman, Mari; Rippe, Catarina; Grossi, Mario; Nilsson, Bengt-Olof; Albinsson, Sebastian; Uvelius, Bengt; Swärd, Karl

    2016-01-01

    Phenotypic modulation of smooth muscle cells is a hallmark of disease. The associated expansion of endoplasmic reticulum (ER) volume remains unexplained. Thrombospondin-4 was recently found to promote ATF6α activation leading to ER expansion. Using bladder outlet obstruction as a paradigm for phenotypic modulation, we tested if thrombospondin-4 is induced in association with ATF6α activation and ER expansion. Thrombospondin-4 was induced and ATF6α was activated after outlet obstruction in rodents. Increased abundance of spliced of Xbp1, another ER-stress sensor, and induction of Atf4 and Creb3l2 was also seen. Downstream of ATF6α, Calr, Manf, Sdf2l1 and Pdi increased as did ER size, whereas contractile markers were reduced. Overexpression of ATF6α, but not of thrombospondin-4, increased Calr, Manf, Sdf2l1 and Pdi and caused ER expansion, but the contractile markers were inert. Knockout of thrombospondin-4 neither affected bladder growth nor expression of ATF6α target genes, and repression of contractile markers was the same, even if ATF6α activation was curtailed. Increases of Xbp1s, Atf4 and Creb3l2 were similar. Our findings demonstrate reciprocal regulation of the unfolded protein response, including ATF6α activation and ER expansion, and reduced contractile differentiation in bladder outlet obstruction occurring independently of thrombospondin-4, which however is a sensitive indicator of obstruction. PMID:27581066

  16. The endoplasmic reticulum as a potential therapeutic target in nonalcoholic fatty liver disease

    PubMed Central

    Gentile, Christopher L; Pagliassotti, Michael J

    2008-01-01

    The endoplasmic reticulum (ER) has emerged as a key to understanding the development and consequences of hepatic fat accumulation in nonalcoholic fatty liver disease (NAFLD). An essential function of this organelle is the proper assembly of proteins that are destined for intracellular organelles and the cell surface. Recent evidence suggests that chemical chaperones that enhance the functional capacity of the ER improve liver function in obesity and NAFLD. These chaperones may therefore provide a novel potential therapeutic strategy in NAFLD. PMID:18821470

  17. Disruption of calpain reduces lipotoxicity-induced cardiac injury by preventing endoplasmic reticulum stress

    PubMed Central

    Li, Shengcun; Zhang, Lulu; Ni, Rui; Cao, Ting; Zheng, Dong; Xiong, Sidong; Greer, Peter A.; Fan, Guo-Chang; Peng, Tianqing

    2016-01-01

    Diabetes and obesity are prevalent in westernized countries. In both conditions, excessive fatty acid uptake by cardiomyocytes induces cardiac lipotoxicity, an important mechanism contributing to diabetic cardiomyopathy. This study investigated the effect of calpain disruption on cardiac lipotoxicity. Cardiac-specific capns1 knockout mice and their wild-type littermates (male, age of 4 weeks) were fed a high fat diet (HFD) or normal diet for 20 weeks. HFD increased body weight, altered blood lipid profiles and impaired glucose tolerance comparably in both capns1 knockout mice and their wild-type littermates. Calpain activity, cardiomyocyte cross-sectional areas, collagen deposition and triglyceride were significantly increased in HFD-fed mouse hearts, and these were accompanied by myocardial dysfunction and up-regulation of hypertrophic and fibrotic collagen genes as well as pro-inflammatory cytokines. These effects of HFD were attenuated by disruption of calpain in capns1 knockout mice. Mechanistically, deletion of capns1 in HFD-fed mouse hearts and disruption of calpain with calpain inhibitor-III, silencing of capn1, or deletion of capns1 in palmitate-stimulated cardiomyocytes prevented endoplasmic reticulum stress, apoptosis, cleavage of caspase-12 and junctophilin-2, and pro-inflammatory cytokine expression. Pharmacological inhibition of endoplasmic reticulum stress diminished palmitate-induced apoptosis and pro-inflammatory cytokine expression in cardiomyocytes. In summary, disruption of calpain prevents lipotoxicity-induced apoptosis in cardiomyocytes and cardiac injury in mice fed a HFD. The role of calpain is mediated, at least partially, through endoplasmic reticulum stress. Thus, calpain/endoplasmic reticulum stress may represent a new mechanism and potential therapeutic targets for cardiac lipotoxicity. PMID:27523632

  18. Overexpression of Tau Protein Inhibits Kinesin-dependent Trafficking of Vesicles, Mitochondria, and Endoplasmic Reticulum: Implications for Alzheimer's Disease

    PubMed Central

    Ebneth, A.; Godemann, R.; Stamer, K.; Illenberger, S.; Trinczek, B.; Mandelkow, E.-M.; Mandelkow, E.

    1998-01-01

    The neuronal microtubule-associated protein tau plays an important role in establishing cell polarity by stabilizing axonal microtubules that serve as tracks for motor-protein–driven transport processes. To investigate the role of tau in intracellular transport, we studied the effects of tau expression in stably transfected CHO cells and differentiated neuroblastoma N2a cells. Tau causes a change in cell shape, retards cell growth, and dramatically alters the distribution of various organelles, known to be transported via microtubule-dependent motor proteins. Mitochondria fail to be transported to peripheral cell compartments and cluster in the vicinity of the microtubule-organizing center. The endoplasmic reticulum becomes less dense and no longer extends to the cell periphery. In differentiated N2a cells, the overexpression of tau leads to the disappearance of mitochondria from the neurites. These effects are caused by tau's binding to microtubules and slowing down intracellular transport by preferential impairment of plus-end–directed transport mediated by kinesin-like motor proteins. Since in Alzheimer's disease tau protein is elevated and mislocalized, these observations point to a possible cause for the gradual degeneration of neurons. PMID:9813097

  19. Endoplasmic reticulum-resident Rab8A GTPase is involved in phagocytosis in the protozoan parasite Entamoeba histolytica.

    PubMed

    Hanadate, Yuki; Saito-Nakano, Yumiko; Nakada-Tsukui, Kumiko; Nozaki, Tomoyoshi

    2016-10-01

    Phagocytosis is indispensable for the pathogenesis of the intestinal protozoan parasite Entamoeba histolytica. Here, we showed that in E. histolytica Rab8A, which is generally involved in trafficking from the trans-Golgi network to the plasma membrane in other organisms but was previously identified in phagosomes of the amoeba in the proteomic analysis, primarily resides in the endoplasmic reticulum (ER) and participates in phagocytosis. We demonstrated that down-regulation of EhRab8A by small antisense RNA-mediated transcriptional gene silencing remarkably reduced adherence and phagocytosis of erythrocytes, bacteria and carboxylated latex beads. Surface biotinylation followed by SDS-PAGE analysis revealed that the surface expression of several proteins presumably involved in target recognition was reduced in the EhRab8A gene-silenced strain. Further, overexpression of wild-type EhRab8A augmented phagocytosis, whereas expression of the dominant-negative form of EhRab8A resulted in reduced phagocytosis. These results indicated that EhRab8A regulates transport of surface receptor(s) for the prey from the ER to the plasma membrane. To our knowledge, this is the first report that the ER-resident Rab GTPase is involved in phagocytosis through the regulation of trafficking of a surface receptor, supporting a premise of direct involvement of the ER in phagocytosis. PMID:26807810

  20. Genes involved in the endoplasmic reticulum N-glycosylation pathway of the red microalga Porphyridium sp.: a bioinformatic study.

    PubMed

    Levy-Ontman, Oshrat; Fisher, Merav; Shotland, Yoram; Weinstein, Yacob; Tekoah, Yoram; Arad, Shoshana Malis

    2014-01-01

    N-glycosylation is one of the most important post-translational modifications that influence protein polymorphism, including protein structures and their functions. Although this important biological process has been extensively studied in mammals, only limited knowledge exists regarding glycosylation in algae. The current research is focused on the red microalga Porphyridium sp., which is a potentially valuable source for various applications, such as skin therapy, food, and pharmaceuticals. The enzymes involved in the biosynthesis and processing of N-glycans remain undefined in this species, and the mechanism(s) of their genetic regulation is completely unknown. In this study, we describe our pioneering attempt to understand the endoplasmic reticulum N-Glycosylation pathway in Porphyridium sp., using a bioinformatic approach. Homology searches, based on sequence similarities with genes encoding proteins involved in the ER N-glycosylation pathway (including their conserved parts) were conducted using the TBLASTN function on the algae DNA scaffold contigs database. This approach led to the identification of 24 encoded-genes implicated with the ER N-glycosylation pathway in Porphyridium sp. Homologs were found for almost all known N-glycosylation protein sequences in the ER pathway of Porphyridium sp.; thus, suggesting that the ER-pathway is conserved; as it is in other organisms (animals, plants, yeasts, etc.).

  1. VAP, a Versatile Access Point for the Endoplasmic Reticulum: Review and analysis of FFAT-like motifs in the VAPome.

    PubMed

    Murphy, Sarah E; Levine, Tim P

    2016-08-01

    Dysfunction of VAMP-associated protein (VAP) is associated with neurodegeneration, both Amyotrophic Lateral Sclerosis and Parkinson's disease. Here we summarize what is known about the intracellular interactions of VAP in humans and model organisms. VAP is a simple, small and highly conserved protein on the cytoplasmic face of the endoplasmic reticulum (ER). It is the sole protein on that large organelle that acts as a receptor for cytoplasmic proteins. This may explain the extremely wide range of interacting partners of VAP, with components of many cellular pathways binding it to access the ER. Many proteins that bind VAP also target other intracellular membranes, so VAP is a component of multiple molecular bridges at membrane contact sites between the ER and other organelles. So far approximately 100 proteins have been identified in the VAP interactome (VAPome), of which a small minority have a "two phenylalanines in an acidic tract" (FFAT) motif as it was originally defined. We have analyzed the entire VAPome in humans and yeast using a simple algorithm that identifies many more FFAT-like motifs. We show that approximately 50% of the VAPome binds directly or indirectly via the VAP-FFAT interaction. We also review evidence on pathogenesis in genetic disorders of VAP, which appear to arise from reduced overall VAP levels, leading to ER stress. It is not possible to identify one single interaction that underlies disease. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.

  2. Endoplasmic reticulum-resident Rab8A GTPase is involved in phagocytosis in the protozoan parasite Entamoeba histolytica.

    PubMed

    Hanadate, Yuki; Saito-Nakano, Yumiko; Nakada-Tsukui, Kumiko; Nozaki, Tomoyoshi

    2016-10-01

    Phagocytosis is indispensable for the pathogenesis of the intestinal protozoan parasite Entamoeba histolytica. Here, we showed that in E. histolytica Rab8A, which is generally involved in trafficking from the trans-Golgi network to the plasma membrane in other organisms but was previously identified in phagosomes of the amoeba in the proteomic analysis, primarily resides in the endoplasmic reticulum (ER) and participates in phagocytosis. We demonstrated that down-regulation of EhRab8A by small antisense RNA-mediated transcriptional gene silencing remarkably reduced adherence and phagocytosis of erythrocytes, bacteria and carboxylated latex beads. Surface biotinylation followed by SDS-PAGE analysis revealed that the surface expression of several proteins presumably involved in target recognition was reduced in the EhRab8A gene-silenced strain. Further, overexpression of wild-type EhRab8A augmented phagocytosis, whereas expression of the dominant-negative form of EhRab8A resulted in reduced phagocytosis. These results indicated that EhRab8A regulates transport of surface receptor(s) for the prey from the ER to the plasma membrane. To our knowledge, this is the first report that the ER-resident Rab GTPase is involved in phagocytosis through the regulation of trafficking of a surface receptor, supporting a premise of direct involvement of the ER in phagocytosis.

  3. Endoplasmic reticulum‐resident Rab8A GTPase is involved in phagocytosis in the protozoan parasite Entamoeba histolytica

    PubMed Central

    Hanadate, Yuki; Saito‐Nakano, Yumiko; Nakada‐Tsukui, Kumiko

    2016-01-01

    Summary Phagocytosis is indispensable for the pathogenesis of the intestinal protozoan parasite Entamoeba histolytica. Here, we showed that in E. histolytica Rab8A, which is generally involved in trafficking from the trans‐Golgi network to the plasma membrane in other organisms but was previously identified in phagosomes of the amoeba in the proteomic analysis, primarily resides in the endoplasmic reticulum (ER) and participates in phagocytosis. We demonstrated that down‐regulation of EhRab8A by small antisense RNA‐mediated transcriptional gene silencing remarkably reduced adherence and phagocytosis of erythrocytes, bacteria and carboxylated latex beads. Surface biotinylation followed by SDS‐PAGE analysis revealed that the surface expression of several proteins presumably involved in target recognition was reduced in the EhRab8A gene‐silenced strain. Further, overexpression of wild‐type EhRab8A augmented phagocytosis, whereas expression of the dominant‐negative form of EhRab8A resulted in reduced phagocytosis. These results indicated that EhRab8A regulates transport of surface receptor(s) for the prey from the ER to the plasma membrane. To our knowledge, this is the first report that the ER‐resident Rab GTPase is involved in phagocytosis through the regulation of trafficking of a surface receptor, supporting a premise of direct involvement of the ER in phagocytosis. PMID:26807810

  4. Structural requirements for inhibitory effects of bisphenols on the activity of the sarco/endoplasmic reticulum calcium ATPase

    PubMed Central

    Woeste, Matthew; Steller, Jeffrey; Hofmann, Emily; Kidd, Taylor; Patel, Rahul; Connolly, Kevin; Jayasinghe, Manori; Paula, Stefan

    2013-01-01

    Bisphenols (BPs) are a class of small organic compounds with widespread industrial applications. Previous studies have identified several BPs that interfere with the activity of the ion-translocating enzyme sarco/endoplasmic reticulum calcium ATPase (SERCA). In order to define the molecular determinants of BP-mediated SERCA inhibition, we conducted enzyme activity assays with rabbit SERCA to determine the inhibitory potencies of 27 commercially available BPs, which were the basis for structure-activity relationships. The most potent BPs inhibited SERCA at low micromolar concentrations and carried at their two phenyl rings multiple non-polar substituents, such as small alkyl groups or halides. Furthermore, the presence of methyl groups or a cyclohexyl group at the central carbon atom connecting the two phenyl moieties correlated with good potencies. For a characterization and visualization of inhibitor/enzyme interactions, molecular docking was performed, which suggested that hydrogen bonding with Asp254 and hydrophobic interactions were the major driving forces for BP binding to SERCA. Calcium imaging studies with a selection of BPs showed that these inhibitors were able to increase intracellular calcium levels in living human cells, a behavior consistent with that of a SERCA inhibitor. PMID:23643898

  5. Correlation-based smoothing model for optical polishing.

    PubMed

    Shu, Yong; Kim, Dae Wook; Martin, Hubert M; Burge, James H

    2013-11-18

    A generalized model is developed to quantitatively describe the smoothing effects from different polishing tools used for optical surfaces. The smoothing effect naturally corrects mid-to-high spatial frequency errors that have features small compared to the size of the polishing lap. The original parametric smoothing model provided a convenient way to compare smoothing efficiency of different polishing tools for the case of sinusoidal surface irregularity, providing the ratio of surface improvement via smoothing to the bulk material removal. A new correlation-based smoothing model expands the capability to quantify smoothing using general surface data with complex irregularity. For this case, we define smoothing as a band-limited correlated component of the change in the surface and original surface. Various concepts and methods, such as correlation screening, have been developed and verified to manipulate the data for the calculation of smoothing factor. Data from two actual polishing runs from the Giant Magellan Telescope off-axis segment and the Large Synoptic Survey Telescope monolithic primary-tertiary mirror were processed, and a quantitative evaluation for the smoothing efficiency of a large pitch lap and a conformal lap with polishing pads is provided.

  6. Endoplasmic reticulum stress: a novel mechanism and therapeutic target for cardiovascular diseases

    PubMed Central

    Liu, Mei-qing; Chen, Zhe; Chen, Lin-xi

    2016-01-01

    Endoplasmic reticulum is a principal organelle responsible for folding, post-translational modifications and transport of secretory, luminal and membrane proteins, thus palys an important rale in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) is a condition that is accelerated by accumulation of unfolded/misfolded proteins after endoplasmic reticulum environment disturbance, triggered by a variety of physiological and pathological factors, such as nutrient deprivation, altered glycosylation, calcium depletion, oxidative stress, DNA damage and energy disturbance, etc. ERS may initiate the unfolded protein response (UPR) to restore cellular homeostasis or lead to apoptosis. Numerous studies have clarified the link between ERS and cardiovascular diseases. This review focuses on ERS-associated molecular mechanisms that participate in physiological and pathophysiological processes of heart and blood vessels. In addition, a number of drugs that regulate ERS was introduced, which may be used to treat cardiovascular diseases. This review may open new avenues for studying the pathogenesis of cardiovascular diseases and discovering novel drugs targeting ERS. PMID:26838072

  7. Cytoplasmic nucleation and atypical branching nucleation generate endoplasmic microtubules in Physcomitrella patens.

    PubMed

    Nakaoka, Yuki; Kimura, Akatsuki; Tani, Tomomi; Goshima, Gohta

    2015-01-01

    The mechanism underlying microtubule (MT) generation in plants has been primarily studied using the cortical MT array, in which fixed-angled branching nucleation and katanin-dependent MT severing predominate. However, little is known about MT generation in the endoplasm. Here, we explored the mechanism of endoplasmic MT generation in protonemal cells of Physcomitrella patens. We developed an assay that utilizes flow cell and oblique illumination fluorescence microscopy, which allowed visualization and quantification of individual MT dynamics. MT severing was infrequently observed, and disruption of katanin did not severely affect MT generation. Branching nucleation was observed, but it showed markedly variable branch angles and was occasionally accompanied by the transport of nucleated MTs. Cytoplasmic nucleation at seemingly random locations was most frequently observed and predominated when depolymerized MTs were regrown. The MT nucleator γ-tubulin was detected at the majority of the nucleation sites, at which a single MT was generated in random directions. When γ-tubulin was knocked down, MT generation was significantly delayed in the regrowth assay. However, nucleation occurred at a normal frequency in steady state, suggesting the presence of a γ-tubulin-independent backup mechanism. Thus, endoplasmic MTs in this cell type are generated in a less ordered manner, showing a broader spectrum of nucleation mechanisms in plants.

  8. The formation of the smooth halo component

    NASA Astrophysics Data System (ADS)

    Peñarrubia, Jorge

    2016-08-01

    The detection and characterization of debris in the integral-of-motion space is a promising avenue to uncover the hierarchical formation of the Milky Way. Yet, the fact that the integrals do not remain constant during the assembly process adds considerable complexity to this approach. Indeed, in time-dependent potentials tidal substructures tend to be effaced from the integral-of-motion space through an orbital diffusion process, which naturally leads to the formation of a `smooth' stellar halo. In this talk I will introduce a new probability theory that describes the evolution of collisionless systems subject to a time-dependent potential. The new theory can be used to reconstruct the hierarchical assembly of our Galaxy through modelling the observed distribution of accreted stars in the integral-of-motion space.

  9. PV output smoothing with energy storage.

    SciTech Connect

    Ellis, Abraham; Schoenwald, David Alan

    2012-03-01

    This report describes an algorithm, implemented in Matlab/Simulink, designed to reduce the variability of photovoltaic (PV) power output by using a battery. The purpose of the battery is to add power to the PV output (or subtract) to smooth out the high frequency components of the PV power that that occur during periods with transient cloud shadows on the PV array. The control system is challenged with the task of reducing short-term PV output variability while avoiding overworking the battery both in terms of capacity and ramp capability. The algorithm proposed by Sandia is purposely very simple to facilitate implementation in a real-time controller. The control structure has two additional inputs to which the battery can respond. For example, the battery could respond to PV variability, load variability or area control error (ACE) or a combination of the three.

  10. An analysis of smoothed particle hydrodynamics

    SciTech Connect

    Swegle, J.W.; Attaway, S.W.; Heinstein, M.W.; Mello, F.J.; Hicks, D.L.

    1994-03-01

    SPH (Smoothed Particle Hydrodynamics) is a gridless Lagrangian technique which is appealing as a possible alternative to numerical techniques currently used to analyze high deformation impulsive loading events. In the present study, the SPH algorithm has been subjected to detailed testing and analysis to determine its applicability in the field of solid dynamics. An important result of the work is a rigorous von Neumann stability analysis which provides a simple criterion for the stability or instability of the method in terms of the stress state and the second derivative of the kernel function. Instability, which typically occurs only for solids in tension, results not from the numerical time integration algorithm, but because the SPH algorithm creates an effective stress with a negative modulus. The analysis provides insight into possible methods for removing the instability. Also, SPH has been coupled into the transient dynamics finite element code PRONTO, and a weighted residual derivation of the SPH equations has been obtained.

  11. Action of acetylcholine on smooth muscle.

    PubMed

    Bolton, T B; Lim, S P

    1991-01-01

    Contraction of smooth muscle by acetylcholine is mediated by activation of muscarinic receptors of which M2 and M3 subtypes are present in longitudinal muscle of guinea pig intestine. In single cells, muscarinic receptor activation evokes calcium release from stores which raises the internal free calcium concentration and causes opening of calcium-activated potassium channels. The rise in internal calcium suppresses the voltage-dependent inward calcium current. A third important effect is the opening of channels which cause depolarization of the membrane and so increase action potential discharge and contraction in the whole muscle. These channels were studied by voltage-clamp of single cells from longitudinal muscle of rabbit small intestine. They were found to be permeable to Na and K but not detectably permeable to Cl. They can pass Ca but the amount entering the cell is not sufficient to raise the internal calcium concentration appreciably.

  12. Smoothness monitors for compressible flow computation

    SciTech Connect

    Sjogreen, B; Yee, H C

    2008-09-02

    In [SY04, YS07] and references cited therein, the authors introduced the concept of employing multiresolution wavelet decomposition of computed flow data as smoothness monitors (flow sensors) to indicate the amount and location of built-in numerical dissipation that can be eliminated or further reduced in shock-capturing schemes. Studies indicated that this approach is able to limit the use of numerical dissipation with improved accuracy compared with standard shock-capturing methods. The studies in [SY04, YS07] were limited to low order multiresolution redundant wavelets with low level supports and low order vanishing moments. The objective of this paper is to expand the previous investigation to include higher order redundant wavelets with larger support and higher order vanishing moments for a wider spectrum of flow type and flow speed applications.

  13. Conduction Modelling Using Smoothed Particle Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Cleary, Paul W.; Monaghan, Joseph J.

    1999-01-01

    Heat transfer is very important in many industrial and geophysical problems. Because these problems often have complicated fluid dynamics, there are advantages in solving them using Lagrangian methods like smoothed particle hydrodynamics (SPH). Since SPH particles become disordered, the second derivative terms may be estimated poorly, especially when materials with different properties are adjacent. In this paper we show how a simple alteration to the standard SPH formulation ensures continuity of heat flux across discontinuities in material properties. A set of rules is formulated for the construction of isothermal boundaries leading to accurate conduction solutions. A method for accurate prediction of heat fluxes through isothermal boundaries is also given. The accuracy of the SPH conduction solutions is demonstrated through a sequence of test problems of increasing complexity.

  14. Smooth Teeth: Why Multipoles Are Perfect Gears

    NASA Astrophysics Data System (ADS)

    Schönke, Johannes

    2015-12-01

    A type of gear is proposed based on the interaction of individual multipoles. The underlying principle relies on previously unknown continuous degenerate ground states for pairs of interacting multipoles which are free to rotate around specific axes. These special rotation axes, in turn, form a one-parameter family of possible configurations. This allows for the construction of magnetic bevel gears with any desired inclination angle between the in- and output axes. Further, the design of gear systems with more than two multipoles is possible and facilitates tailored applications. Ultimately, an analogy between multipoles and mechanical gears is revealed. In contrast to the mechanical case, the multipole "teeth" mesh smoothly. As an illustrative application, the example of a quadrupole-dipole interaction is then used to construct a 1 ∶2 gear ratio.

  15. Computational brittle fracture using smooth particle hydrodynamics

    SciTech Connect

    Mandell, D.A.; Wingate, C.A.; Schwalbe, L.A.

    1996-10-01

    We are developing statistically based, brittle-fracture models and are implementing them into hydrocodes that can be used for designing systems with components of ceramics, glass, and/or other brittle materials. Because of the advantages it has simulating fracture, we are working primarily with the smooth particle hydrodynamics code SPBM. We describe a new brittle fracture model that we have implemented into SPBM. To illustrate the code`s current capability, we have simulated a number of experiments. We discuss three of these simulations in this paper. The first experiment consists of a brittle steel sphere impacting a plate. The experimental sphere fragment patterns are compared to the calculations. The second experiment is a steel flyer plate in which the recovered steel target crack patterns are compared to the calculated crack patterns. We also briefly describe a simulation of a tungsten rod impacting a heavily confined alumina target, which has been recently reported on in detail.

  16. Smooth Pursuit of Flicker-Defined Motion

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.; Stevenson, Scott B.

    2014-01-01

    We examined the pursuit response to stimuli defined by space-variant flicker of a dense random dot carrier pattern. On each frame, every element of the pattern could change polarity, with a probability given by a two-dimensional Gaussian distribution. A normal distribution produces a circular region of twinkle, while inverting the distribution results in a spot of static texture in a twinkling surround. In this latter case, the carrier texture could be stationary, or could move with the twinkle modulator, thereby producing first-order motion in the region of the spot. While the twinkle-defined spot produces a strong sensation of motion, the complementary stimulus defined by the absence of twinkle does not, when viewed peripherally, it appears to move in steps even when the generating distribution moves smoothly. We examined pursuit responses to these stimuli using two techniques: 1) the eye movement correlogram, obtained by cross-correlating eye velocity with the velocity of a randomly-moving stimulus; and 2) delayed visual feedback, where transient stabilization of a target can produce spontaneous oscillations of the eye, with a period empirically observed to vary linearly with the applied delay. Both techniques provide an estimate of the internal processing time, which can be as short as 100 milliseconds for a first-order target. Assessed by the correlogram method, the response to flicker-defined motion is delayed by more than 100 milliseconds, and significantly weaker (especially in the vertical dimension). When initially presented in the delayed feedback condition, purely saccadic oscillation is observed. One subject eventually developed smooth oscillations (albeit with significant saccadic intrusions), showing a period-versus-delay slope similar to that observed for first-order targets. This result is somewhat surprising, given that we interpret the slope of the period-versus-delay-function as reflecting the balance between position- and velocity

  17. Local, smooth, and consistent Jacobi set simplification

    SciTech Connect

    Bhatia, Harsh; Wang, Bei; Norgard, Gregory; Pascucci, Valerio; Bremer, Peer -Timo

    2014-10-31

    The relation between two Morse functions defined on a smooth, compact, and orientable 2-manifold can be studied in terms of their Jacobi set. The Jacobi set contains points in the domain where the gradients of the two functions are aligned. Both the Jacobi set itself as well as the segmentation of the domain it induces, have shown to be useful in various applications. In practice, unfortunately, functions often contain noise and discretization artifacts, causing their Jacobi set to become unmanageably large and complex. Although there exist techniques to simplify Jacobi sets, they are unsuitable for most applications as they lack fine-grained control over the process, and heavily restrict the type of simplifications possible. In this paper, we introduce a new framework that generalizes critical point cancellations in scalar functions to Jacobi set in two dimensions. We present a new interpretation of Jacobi set simplification based on the perspective of domain segmentation. Generalizing the cancellation of critical points from scalar functions to Jacobi sets, we focus on simplifications that can be realized by smooth approximations of the corresponding functions, and show how these cancellations imply simultaneous simplification of contiguous subsets of the Jacobi set. Using these extended cancellations as atomic operations, we introduce an algorithm to successively cancel subsets of the Jacobi set with minimal modifications to some user-defined metric. We show that for simply connected domains, our algorithm reduces a given Jacobi set to its minimal configuration, that is, one with no birth–death points (a birth–death point is a specific type of singularity within the Jacobi set where the level sets of the two functions and the Jacobi set have a common normal direction).

  18. Local, smooth, and consistent Jacobi set simplification

    DOE PAGESBeta

    Bhatia, Harsh; Wang, Bei; Norgard, Gregory; Pascucci, Valerio; Bremer, Peer -Timo

    2014-10-31

    The relation between two Morse functions defined on a smooth, compact, and orientable 2-manifold can be studied in terms of their Jacobi set. The Jacobi set contains points in the domain where the gradients of the two functions are aligned. Both the Jacobi set itself as well as the segmentation of the domain it induces, have shown to be useful in various applications. In practice, unfortunately, functions often contain noise and discretization artifacts, causing their Jacobi set to become unmanageably large and complex. Although there exist techniques to simplify Jacobi sets, they are unsuitable for most applications as they lackmore » fine-grained control over the process, and heavily restrict the type of simplifications possible. In this paper, we introduce a new framework that generalizes critical point cancellations in scalar functions to Jacobi set in two dimensions. We present a new interpretation of Jacobi set simplification based on the perspective of domain segmentation. Generalizing the cancellation of critical points from scalar functions to Jacobi sets, we focus on simplifications that can be realized by smooth approximations of the corresponding functions, and show how these cancellations imply simultaneous simplification of contiguous subsets of the Jacobi set. Using these extended cancellations as atomic operations, we introduce an algorithm to successively cancel subsets of the Jacobi set with minimal modifications to some user-defined metric. We show that for simply connected domains, our algorithm reduces a given Jacobi set to its minimal configuration, that is, one with no birth–death points (a birth–death point is a specific type of singularity within the Jacobi set where the level sets of the two functions and the Jacobi set have a common normal direction).« less

  19. Diffusion tensor smoothing through weighted Karcher means.

    PubMed

    Carmichael, Owen; Chen, Jun; Paul, Debashis; Peng, Jie

    2013-01-01

    Diffusion tensor magnetic resonance imaging (MRI) quantifies the spatial distribution of water Diffusion at each voxel on a regular grid of locations in a biological specimen by Diffusion tensors- 3 × 3 positive definite matrices. Removal of noise from DTI is an important problem due to the high scientific relevance of DTI and relatively low signal to noise ratio it provides. Leading approaches to this problem amount to estimation of weighted Karcher means of Diffusion tensors within spatial neighborhoods, under various metrics imposed on the space of tensors. However, it is unclear how the behavior of these estimators varies with the magnitude of DTI sensor noise (the noise resulting from the thermal e!ects of MRI scanning) as well as the geometric structure of the underlying Diffusion tensor neighborhoods. In this paper, we combine theoretical analysis, empirical analysis of simulated DTI data, and empirical analysis of real DTI scans to compare the noise removal performance of three kernel-based DTI smoothers that are based on Euclidean, log-Euclidean, and affine-invariant metrics. The results suggest, contrary to conventional wisdom, that imposing a simplistic Euclidean metric may in fact provide comparable or superior noise removal, especially in relatively unstructured regions and/or in the presence of moderate to high levels of sensor noise. On the contrary, log-Euclidean and affine-invariant metrics may lead to better noise removal in highly structured anatomical regions, especially when the sensor noise is of low magnitude. These findings emphasize the importance of considering the interplay of sensor noise magnitude and tensor field geometric structure when assessing Diffusion tensor smoothing options. They also point to the necessity for continued development of smoothing methods that perform well across a large range of scenarios. PMID:25419264

  20. Biosynthesis of cytochrome P-450 on membrane-bound ribosomes and its subsequent incorporation into rough and smooth microsomes in rat hepatocytes

    PubMed Central

    1979-01-01

    Intracellular sites of synthesis of cytochrome P-450 and the subsequent incorporation of it into membrane structures of the endoplasmic reticulum (ER) in rat hepatocytes have been studied using an antibody monospecific for phenobarbital-inducible cytochrome P-450. The cytochrome is synthesized mainly on the "tightly bound" type of membrane-bound ribosomes whose release from the membrane requires treatment with puromycin in a high salt buffer (500 mM KCI, 5mM MgCl2, and 50 mM Tris-HCL [pH 7.5]). Subsequently the cytochrome is incorporated directly into the rough ER membranes with its major part exposed to the outer surface to the membrane and accessible to proteolytic enzymes added externally. The newly synthesized molecules, which appeared first in the rough membrane, are translocated to the smooth membrane, and are then distributed evenly between the two types of microsomeal membranes in approximately 1 h. Administration of cycloheximide, an inhibitor of protein biosynthesis, did not significantly inhibit the transfer of the enzyme from the rough to the smooth ER. It is suggested, therefore, that the translocation of the newly synthesized cythochrome P-450 between the rough and smooth microsomes is mainly due to the lateral movement of the molecules in the plane of the membranes rather than to the attachment and detachment of the ribosomes on the microsomal membranes after the ribosomal cycle for protein synthesis. PMID:457773

  1. In vitro differentiation of porcine aortic vascular precursor cells to endothelial and vascular smooth muscle cells.

    PubMed

    Zaniboni, Andrea; Bernardini, Chiara; Bertocchi, Martina; Zannoni, Augusta; Bianchi, Francesca; Avallone, Giancarlo; Mangano, Chiara; Sarli, Giuseppe; Calzà, Laura; Bacci, Maria Laura; Forni, Monica

    2015-09-01

    Recent findings suggest that progenitor and multipotent mesenchymal stromal cells (MSCs) are associated with vascular niches. Cells displaying mesenchymal properties and differentiating to whole components of a functional blood vessel, including endothelial and smooth muscle cells, can be defined as vascular stem cells (VSCs). Recently, we isolated a population of porcine aortic vascular precursor cells (pAVPCs), which have MSC- and pericyte-like properties. The aim of the present work was to investigate whether pAVPCs possess VSC-like properties and assess their differentiation potential toward endothelial and smooth muscle lineages. pAVPCs, maintained in a specific pericyte growth medium, were cultured in high-glucose DMEM + 10% FBS (long-term medium, LTM) or in human endothelial serum-free medium + 5% FBS and 50 ng/ml of hVEGF (endothelial differentiation medium, EDM). After 21 days of culture in LTM, pAVPCs showed an elongated fibroblast-like morphology, and they seem to organize in cord-like structures. qPCR analysis of smooth muscle markers [α-smooth muscle actin (α-SMA), calponin, and smooth muscle myosin (SMM) heavy chain] showed a significant increment of the transcripts, and immunofluorescence analysis confirmed the presence of α-SMA and SMM proteins. After 21 days of culture in EDM, pAVPCs displayed an endothelial cell-like morphology and revealed the upregulation of the expression of endothelial markers (CD31, vascular endothelial-cadherin, von Willebrand factor, and endothelial nitric oxide synthase) showing the CD31-typical pattern. In conclusion, pAVPCs could be defined as a VSC-like population considering that, if they are maintained in a specific pericyte medium, they express MSC markers, and they have, in addition to the classical mesenchymal trilineage differentiation potential, the capacity to differentiate in vitro toward the smooth muscle and the endothelial cell phenotypes.

  2. Anisotropic Smoothing Improves DT-MRI-Based Muscle Fiber Tractography

    PubMed Central

    Buck, Amanda K. W.; Ding, Zhaohua; Elder, Christopher P.; Towse, Theodore F.; Damon, Bruce M.

    2015-01-01

    Purpose To assess the effect of anisotropic smoothing on fiber tracking measures, including pennation angle, fiber tract length, and fiber tract number in the medial gastrocnemius (MG) muscle in healthy subjects using diffusion-weighted magnetic resonance imaging (DW-MRI). Materials and Methods 3T DW-MRI data were used for muscle fiber tractography in the MG of healthy subjects. Anisotropic smoothing was applied at three levels (5%, 10%, 15%), and pennation angle, tract length, fiber tract number, fractional anisotropy, and principal eigenvector orientation were quantified for each smoothing level. Results Fiber tract length increased with pre-fiber tracking smoothing, and local heterogeneities in fiber direction were reduced. However, pennation angle was not affected by smoothing. Conclusion Modest anisotropic smoothing (10%) improved fiber-tracking results, while preserving structural features. PMID:26010830

  3. Comparison of smoothing methods for the development of a smoothed seismicity model for Alaska and the implications for seismic hazard

    NASA Astrophysics Data System (ADS)

    Moschetti, M. P.; Mueller, C. S.; Boyd, O. S.; Petersen, M. D.

    2013-12-01

    In anticipation of the update of the Alaska seismic hazard maps (ASHMs) by the U. S. Geological Survey, we report progress on the comparison of smoothed seismicity models developed using fixed and adaptive smoothing algorithms, and investigate the sensitivity of seismic hazard to the models. While fault-based sources, such as those for great earthquakes in the Alaska-Aleutian subduction zone and for the ~10 shallow crustal faults within Alaska, dominate the seismic hazard estimates for locations near to the sources, smoothed seismicity rates make important contributions to seismic hazard away from fault-based sources and where knowledge of recurrence and magnitude is not sufficient for use in hazard studies. Recent developments in adaptive smoothing methods and statistical tests for evaluating and comparing rate models prompt us to investigate the appropriateness of adaptive smoothing for the ASHMs. We develop smoothed seismicity models for Alaska using fixed and adaptive smoothing methods and compare the resulting models by calculating and evaluating the joint likelihood test. We use the earthquake catalog, and associated completeness levels, developed for the 2007 ASHM to produce fixed-bandwidth-smoothed models with smoothing distances varying from 10 to 100 km and adaptively smoothed models. Adaptive smoothing follows the method of Helmstetter et al. and defines a unique smoothing distance for each earthquake epicenter from the distance to the nth nearest neighbor. The consequence of the adaptive smoothing methods is to reduce smoothing distances, causing locally increased seismicity rates, where seismicity rates are high and to increase smoothing distances where seismicity is sparse. We follow guidance from previous studies to optimize the neighbor number (n-value) by comparing model likelihood values, which estimate the likelihood that the observed earthquake epicenters from the recent catalog are derived from the smoothed rate models. We compare likelihood

  4. Comparison of smoothing methods for the development of a smoothed seismicity model for Alaska and the implications for seismic hazard

    USGS Publications Warehouse

    Moschetti, Morgan P.; Mueller, Charles S.; Boyd, Oliver S.; Petersen, Mark D.

    2014-01-01

    In anticipation of the update of the Alaska seismic hazard maps (ASHMs) by the U. S. Geological Survey, we report progress on the comparison of smoothed seismicity models developed using fixed and adaptive smoothing algorithms, and investigate the sensitivity of seismic hazard to the models. While fault-based sources, such as those for great earthquakes in the Alaska-Aleutian subduction zone and for the ~10 shallow crustal faults within Alaska, dominate the seismic hazard estimates for locations near to the sources, smoothed seismicity rates make important contributions to seismic hazard away from fault-based sources and where knowledge of recurrence and magnitude is not sufficient for use in hazard studies. Recent developments in adaptive smoothing methods and statistical tests for evaluating and comparing rate models prompt us to investigate the appropriateness of adaptive smoothing for the ASHMs. We develop smoothed seismicity models for Alaska using fixed and adaptive smoothing methods and compare the resulting models by calculating and evaluating the joint likelihood test. We use the earthquake catalog, and associated completeness levels, developed for the 2007 ASHM to produce fixed-bandwidth-smoothed models with smoothing distances varying from 10 to 100 km and adaptively smoothed models. Adaptive smoothing follows the method of Helmstetter et al. and defines a unique smoothing distance for each earthquake epicenter from the distance to the nth nearest neighbor. The consequence of the adaptive smoothing methods is to reduce smoothing distances, causing locally increased seismicity rates, where seismicity rates are high and to increase smoothing distances where seismicity is sparse. We follow guidance from previous studies to optimize the neighbor number (n-value) by comparing model likelihood values, which estimate the likelihood that the observed earthquake epicenters from the recent catalog are derived from the smoothed rate models. We compare likelihood

  5. Nuclear fusion-independent smooth muscle differentiation of human adipose-derived stem cells induced by a smooth muscle environment.

    PubMed

    Zhang, Rong; Jack, Gregory S; Rao, Nagesh; Zuk, Patricia; Ignarro, Louis J; Wu, Benjamin; Rodríguez, Larissa V

    2012-03-01

    Human adipose-derived stem cells hASC have been isolated and were shown to have multilineage differentiation capacity. Although both plasticity and cell fusion have been suggested as mechanisms for cell differentiation in vivo, the effect of the local in vivo environment on the differentiation of adipose-derived stem cells has not been evaluated. We previously reported the in vitro capacity of smooth muscle differentiation of these cells. In this study, we evaluate the effect of an in vivo smooth muscle environment in the differentiation of hASC. We studied this by two experimental designs: (a) in vivo evaluation of smooth muscle differentiation of hASC injected into a smooth muscle environment and (b) in vitro evaluation of smooth muscle differentiation capacity of hASC exposed to bladder smooth muscle cells. Our results indicate a time-dependent differentiation of hASC into mature smooth muscle cells when these cells are injected into the smooth musculature of the urinary bladder. Similar findings were seen when the cells were cocultured in vitro with primary bladder smooth muscle cells. Chromosomal analysis demonstrated that microenvironment cues rather than nuclear fusion are responsible for this differentiation. We conclude that cell plasticity is present in hASCs, and their differentiation is accomplished in the absence of nuclear fusion.

  6. SIMS: computation of a smooth invariant molecular surface.

    PubMed Central

    Vorobjev, Y N; Hermans, J

    1997-01-01

    SIMS, a new method of calculating a smooth invariant molecular dot surface, is presented. The SIMS method generates the smooth molecular surface by rolling two probe spheres. A solvent probe sphere is rolled over the molecule and produces a Richards-Connolly molecular surface (MS), which envelops the solvent-excluded volume of the molecule. In deep crevices, Connolly's method of calculating the MS has two deficiencies. First, it produces self-intersecting parts of the molecular surface, which must be removed to obtain the correct MS. Second, the correct MS is not smooth, i.e., the direction of the normal vector of the MS is not continuous, and some points of the MS are singular. We present an exact method for removing self-intersecting parts and smoothing the singular regions of the MS. The singular MS is smoothed by rolling a smoothing probe sphere over the inward side of the singular MS. The MS in the vicinity of singularities is replaced with the reentrant surface of the smoothing probe sphere. The smoothing method does not disturb the topology of a singular MS, and the smooth MS is a better approximation of the dielectric border between high dielectric solvent and the low dielectric molecular interior. The SIMS method generates a smooth molecular dot surface, which has a quasi-uniform dot distribution in two orthogonal directions on the molecular surface, which is invariant with molecular rotation and stable under changes in the molecular conformation, and which can be used in a variety of implicit methods of modeling solvent effects. The SIMS program is faster than the Connolly MS program, and in a matter of seconds generates a smooth dot MS of a 200-residue protein. The program is available from the authors on request (see http:@femto.med.unc.edu/SIMS). PMID:9251789

  7. P2Y2 Receptor-mediated Lymphotoxin-α Secretion Regulates Intercellular Cell Adhesion Molecule-1 Expression in Vascular Smooth Muscle Cells*

    PubMed Central

    Seye, Cheikh I.; Agca, Yuksel; Agca, Cansu; Derbigny, Wilbert

    2012-01-01

    The proinflammatory cytokine lymphotoxin-α (LTA) is thought to contribute to the pathogenesis of atherosclerosis. However, the mechanisms that regulate its expression in vascular smooth muscle cells (VSMC) are poorly understood. The ability of exogenous nucleotides to stimulate LTA production was evaluated in VSMC by ELISA. The P2Y2 nucleotide receptor (P2Y2R) agonist UTP stimulates a strong and sustained release of LTA from WT but not P2Y2R−/− SMC. Assessment of LTA gene transcription by LTA promoter-luciferase construct indicated that LTA levels are controlled at the level of transcription. We show using RNAi techniques that knockdown of the actin-binding protein filamin-A (FLNa) severely impaired nucleotide-induced Rho activation and consequent Rho-mediated LTA secretion. Reintroduction of FLNa in FLNa RNAi SMC rescued UTP-induced LTA expression. In addition, we found that UTP-stimulated LTA secretion is not sensitive to brefeldin A, which blocks the formation of vesicles involved in protein transport from the endoplasmic reticulum to the Golgi apparatus, suggesting that P2Y2R/filamin-mediated secretion of LTA is independent of the endoplasmic reticulum/Golgi secretory vesicle route. Furthermore, UTP selectively induces ICAM-1 expression in WT but not SMC expressing a truncated P2Y2R deficient in LTA secretion. These data suggest that P2Y2R recruits FLNa to provide a cytoskeletal scaffold necessary for Rho signaling pathway upstream of LTA release and subsequent stimulation of ICAM-1 expression on vascular smooth muscle cells. PMID:22298782

  8. Smooth Muscle Cell Contraction Increases the Critical Buckling Pressure of Arteries

    PubMed Central

    Hayman, Danika M.; Zhang, Jinzhou; Liu, Qin; Xiao, Yangming; Han, Hai-Chao

    2012-01-01

    Recent in vitro experiments demonstrated that arteries under increased internal pressure or decreased axial stretch may buckle into the tortuous pattern that is commonly observed in aging or diseased arteries in vivo. It suggests that buckling is a possible mechanism for the development of artery tortuosity. Vascular tone has significant effects on arterial mechanical properties but its effect on artery buckling is unknown. The objective of this study was to determine the effects of smooth muscle cell contraction on the critical buckling pressure of arteries. Porcine common carotid arteries were perfused in an ex vivo organ culture system overnight under physiological flow and pressure. The perfusion pressure was adjusted to determine the critical buckling pressure of these arteries at in vivo and reduced axial stretch ratios (1.5 and 1.3) at baseline and after smooth muscle contraction and relaxation stimulated by norepinephrine and sodium nitroprusside, respectively. Our results demonstrated that the critical buckling pressure was significantly higher when the smooth muscle was contracted compared with relaxed condition (97.3mmHg versus 72.9mmHg at axial stretch ratio of 1.3 and 93.7mmHg vs 58.6mmHg at 1.5, p<0.05). These results indicate that arterial smooth muscle cell contraction increased artery stability. PMID:23261241

  9. Smooth muscle cell contraction increases the critical buckling pressure of arteries.

    PubMed

    Hayman, Danika M; Zhang, Jinzhou; Liu, Qin; Xiao, Yangming; Han, Hai-Chao

    2013-02-22

    Recent in vitro experiments demonstrated that arteries under increased internal pressure or decreased axial stretch may buckle into the tortuous pattern that is commonly observed in aging or diseased arteries in vivo. It suggests that buckling is a possible mechanism for the development of artery tortuosity. Vascular tone has significant effects on arterial mechanical properties but its effect on artery buckling is unknown. The objective of this study was to determine the effects of smooth muscle cell contraction on the critical buckling pressure of arteries. Porcine common carotid arteries were perfused in an ex vivo organ culture system overnight under physiological flow and pressure. The perfusion pressure was adjusted to determine the critical buckling pressure of these arteries at in vivo and reduced axial stretch ratios (1.5 and 1.3) at baseline and after smooth muscle contraction and relaxation stimulated by norepinephrine and sodium nitroprusside, respectively. Our results demonstrated that the critical buckling pressure was significantly higher when the smooth muscle was contracted compared with relaxed condition (97.3mmHg vs 72.9mmHg at axial stretch ratio of 1.3 and 93.7mmHg vs 58.6mmHg at 1.5, p<0.05). These results indicate that arterial smooth muscle cell contraction increased artery stability.

  10. Swine confinement buildings: effects of airborne particles and settled dust on airway smooth muscles.

    PubMed

    Demanche, Annick; Bonlokke, Jakob; Beaulieu, Marie-Josee; Assayag, Evelyne; Cormier, Yvon

    2009-01-01

    Swine confinement workers are exposed to various contaminants. These agents can cause airway inflammation and bronchoconstriction. This study was undertaken to evaluate if the bronchoconstrictive effects of swine barn air and settled dust are mediated by endotoxin, and if these effects are directly mediated on airway smooth muscles. Mouse tracheas where isolated and mounted isometrically in organ baths. Tracheas, with or without epithelium, were attached to a force transducer and tension was recorded. Concentrated swine building air at 68 EU/ml or settled dust extract at 0.01 g/ml were added for 20 minutes and tracheal smooth muscle contraction was measured. Direct role of LPS was assessed by removing it from air concentrates with an endotoxin affinity resin. Swine barn air and settled dust extract caused contraction of tracheal smooth muscle by 26 and 20%, respectively, of the maximal induced by methacholine. Removal of epithelium did not affect the contractile effects. LPS alone and LPS with peptidoglycans did not induce contraction. However, when endotoxin was removed from swine barn air concentrates, it lost 24% of its contractile effect. Concentrated swine barn air and settled dust have direct effects on airway smooth muscles. This effect is partially due to LPS but a synergy with other components of the environment of swine confinement buildings is required. PMID:20047256

  11. FosB regulates stretch-induced expression of extracellular matrix proteins in smooth muscle.

    PubMed

    Ramachandran, Aruna; Gong, Edward M; Pelton, Kristine; Ranpura, Sandeep A; Mulone, Michelle; Seth, Abhishek; Gomez, Pablo; Adam, Rosalyn M

    2011-12-01

    Fibroproliferative remodeling in smooth muscle-rich hollow organs is associated with aberrant extracellular matrix (ECM) production. Although mechanical stimuli regulate ECM protein expression, the transcriptional mediators of this process remain poorly defined. Previously, we implicated AP-1 as a mediator of smooth muscle cell (SMC) mechanotransduction; however, its role in stretch-induced ECM regulation has not been explored. Herein, we identify a novel role for the AP-1 subunit FosB in stretch-induced ECM expression in SMCs. The DNA-binding activity of AP-1 increased after stretch stimulation of SMCs in vitro. In contrast to c-Jun and c-fos, which are also activated by the SMC mitogen platelet-derived growth factor, FosB was only activated by stretch. FosB silencing attenuated the expression of the profibrotic factors tenascin C (TNC) and connective tissue growth factor (CTGF), whereas forced expression of Jun~FosB stimulated TNC and CTGF promoter activity. Chromatin immunoprecipitation revealed enrichment of AP-1 at the TNC and CTGF promoters. Bladder distension in vivo enhanced nuclear localization of c-jun and FosB. Finally, the distension-induced expression of TNC and CTGF in the detrusor smooth muscle of bladders from wild-type mice was significantly attenuated in FosB-null mice. Together, these findings identify FosB as a mechanosensitive regulator of ECM production in smooth muscle. PMID:21996678

  12. An implicit Smooth Particle Hydrodynamic code

    SciTech Connect

    Charles E. Knapp

    2000-04-01

    An implicit version of the Smooth Particle Hydrodynamic (SPH) code SPHINX has been written and is working. In conjunction with the SPHINX code the new implicit code models fluids and solids under a wide range of conditions. SPH codes are Lagrangian, meshless and use particles to model the fluids and solids. The implicit code makes use of the Krylov iterative techniques for solving large linear-systems and a Newton-Raphson method for non-linear corrections. It uses numerical derivatives to construct the Jacobian matrix. It uses sparse techniques to save on memory storage and to reduce the amount of computation. It is believed that this is the first implicit SPH code to use Newton-Krylov techniques, and is also the first implicit SPH code to model solids. A description of SPH and the techniques used in the implicit code are presented. Then, the results of a number of tests cases are discussed, which include a shock tube problem, a Rayleigh-Taylor problem, a breaking dam problem, and a single jet of gas problem. The results are shown to be in very good agreement with analytic solutions, experimental results, and the explicit SPHINX code. In the case of the single jet of gas case it has been demonstrated that the implicit code can do a problem in much shorter time than the explicit code. The problem was, however, very unphysical, but it does demonstrate the potential of the implicit code. It is a first step toward a useful implicit SPH code.

  13. Vascular Smooth Muscle Cells in Atherosclerosis.

    PubMed

    Bennett, Martin R; Sinha, Sanjay; Owens, Gary K

    2016-02-19

    The historical view of vascular smooth muscle cells (VSMCs) in atherosclerosis is that aberrant proliferation of VSMCs promotes plaque formation, but that VSMCs in advanced plaques are entirely beneficial, for example preventing rupture of the fibrous cap. However, this view has been based on ideas that there is a homogenous population of VSMCs within the plaque, that can be identified separate from other plaque cells (particularly macrophages) using standard VSMC and macrophage immunohistochemical markers. More recent genetic lineage tracing studies have shown that VSMC phenotypic switching results in less-differentiated forms that lack VSMC markers including macrophage-like cells, and this switching directly promotes atherosclerosis. In addition, VSMC proliferation may be beneficial throughout atherogenesis, and not just in advanced lesions, whereas VSMC apoptosis, cell senescence, and VSMC-derived macrophage-like cells may promote inflammation. We review the effect of embryological origin on VSMC behavior in atherosclerosis, the role, regulation and consequences of phenotypic switching, the evidence for different origins of VSMCs, and the role of individual processes that VSMCs undergo in atherosclerosis in regard to plaque formation and the structure of advanced lesions. We think there is now compelling evidence that a full understanding of VSMC behavior in atherosclerosis is critical to identify therapeutic targets to both prevent and treat atherosclerosis.

  14. Immortalization of primary human smooth muscle cells.

    PubMed Central

    Perez-Reyes, N; Halbert, C L; Smith, P P; Benditt, E P; McDougall, J K

    1992-01-01

    Primary human aortic and myometrial smooth muscle cells (SMCs) were immortalized using an amphotropic recombinant retroviral construct containing the E6 and E7 open reading frames (ORFs) of human papillomavirus type 16. The SMCs expressing the E6/E7 ORFs have considerably elevated growth rates when compared with nonimmortalized control cells and show no signs of senescence with long-term passage. The first SMC line derived in this study has been maintained in continuous tissue culture for greater than 1 year (greater than 180 population doublings). The immortalized SMCs have decreased cell size and decreased content of muscle-specific alpha-actin filaments as determined by indirect immunofluorescence. Southern blot analysis has demonstrated the stable integration of the E6/E7 ORFs in the retrovirally infected cells, and radioimmunoprecipitation has confirmed the continued expression of the E6 and E7 genes. Cytogenetic studies of the SMC lines have revealed essentially diploid populations except for the myometrial clonal line, which became aneuploid at late passage (greater than 125 doublings). These cell lines were not tumorigenic in nude mice. Images PMID:1311088

  15. Smooth cubic commensurate oxides on gallium nitride

    SciTech Connect

    Paisley, Elizabeth A.; Gaddy, Benjamin E.; LeBeau, James M.; Shelton, Christopher T.; Losego, Mark D.; Mita, Seiji; Collazo, Ramón; Sitar, Zlatko; Irving, Douglas L.; Maria, Jon-Paul; Biegalski, Michael D.; Christen, Hans M.

    2014-02-14

    Smooth, commensurate alloys of 〈111〉-oriented Mg{sub 0.52}Ca{sub 0.48}O (MCO) thin films are demonstrated on Ga-polar, c+ [0001]-oriented GaN by surfactant-assisted molecular beam epitaxy and pulsed laser deposition. These are unique examples of coherent cubic oxide|nitride interfaces with structural and morphological perfection. Metal-insulator-semiconductor capacitor structures were fabricated on n-type GaN. A comparison of leakage current density for conventional and surfactant-assisted growth reveals a nearly 100× reduction in leakage current density for the surfactant-assisted samples. HAADF-STEM images of the MCO|GaN interface show commensurate alignment of atomic planes with minimal defects due to lattice mismatch. STEM and DFT calculations show that GaN c/2 steps create incoherent boundaries in MCO over layers which manifest as two in-plane rotations and determine consequently the density of structural defects in otherwise coherent MCO. This new understanding of interfacial steps between HCP and FCC crystals identifies the steps needed to create globally defect-free heterostructures.

  16. Smoothing Rotation Curves and Mass Profiles

    NASA Astrophysics Data System (ADS)

    Berrier, Joel C.; Sellwood, J. A.

    2015-02-01

    We show that spiral activity can erase pronounced features in disk galaxy rotation curves. We present simulations of growing disks, in which the added material has a physically motivated distribution, as well as other examples of physically less realistic accretion. In all cases, attempts to create unrealistic rotation curves were unsuccessful because spiral activity rapidly smoothed away features in the disk mass profile. The added material was redistributed radially by the spiral activity, which was itself provoked by the density feature. In the case of a ridge-like feature in the surface density profile, we show that two unstable spiral modes develop, and the associated angular momentum changes in horseshoe orbits remove particles from the ridge and spread them both inward and outward. This process rapidly erases the density feature from the disk. We also find that the lack of a feature when transitioning from disk to halo dominance in the rotation curves of disk galaxies, the so called "disk-halo conspiracy," could also be accounted for by this mechanism. We do not create perfectly exponential mass profiles in the disk, but suggest that this mechanism contributes to their creation.

  17. PDE Based Algorithms for Smooth Watersheds.

    PubMed

    Hodneland, Erlend; Tai, Xue-Cheng; Kalisch, Henrik

    2016-04-01

    Watershed segmentation is useful for a number of image segmentation problems with a wide range of practical applications. Traditionally, the tracking of the immersion front is done by applying a fast sorting algorithm. In this work, we explore a continuous approach based on a geometric description of the immersion front which gives rise to a partial differential equation. The main advantage of using a partial differential equation to track the immersion front is that the method becomes versatile and may easily be stabilized by introducing regularization terms. Coupling the geometric approach with a proper "merging strategy" creates a robust algorithm which minimizes over- and under-segmentation even without predefined markers. Since reliable markers defined prior to segmentation can be difficult to construct automatically for various reasons, being able to treat marker-free situations is a major advantage of the proposed method over earlier watershed formulations. The motivation for the methods developed in this paper is taken from high-throughput screening of cells. A fully automated segmentation of single cells enables the extraction of cell properties from large data sets, which can provide substantial insight into a biological model system. Applying smoothing to the boundaries can improve the accuracy in many image analysis tasks requiring a precise delineation of the plasma membrane of the cell. The proposed segmentation method is applied to real images containing fluorescently labeled cells, and the experimental results show that our implementation is robust and reliable for a variety of challenging segmentation tasks.

  18. A Smoothed Particle Hydrodynamics approach for poroelasticity

    NASA Astrophysics Data System (ADS)

    Osorno, Maria; Steeb, Holger

    2016-04-01

    Within the framework of the SHynergie project we look to investigate hydraulic fracturing and crack evolving in poroelastic media. We model biphasic media assuming incompressible solid grain and incompressible pore liquid. Modeling evolving fractures and fracture networks in elastic and poroelastic media by mesh-based numerical approaches, like X-FEM, is especially in 3-dim a challenging task. Therefore, we propose a meshless particle method for fractured media based on the Smoothed Particle Hydrodynamics (SPH) approach. SPH is a meshless Lagrangian method highly suitable for the simulation of large deformations including free surfaces and/or interfaces. Within the SPH method, the computational domain is discretized with particles, avoiding the computational expenses of meshing. Our SPH solution is implemented in a parallel computational framework, which allows to simulate large domains more representative of the scale of our study cases. Our implementation is carefully validated against classical mesh-based approaches and compared with classical solutions for consolidation problems. Furthermore, we discuss fracture initiation and propagation in poroelastic rocks at the reservoir scale.

  19. Drop splash on a smooth, dry surface

    NASA Astrophysics Data System (ADS)

    Riboux, Guillaume; Gordillo, Jose Manuel; Korobkin, Alexander

    2013-11-01

    It is our purpose here to determine the conditions under which a drop of a given liquid with a known radius R impacting against a smooth impermeable surface at a velocity V, will either spread axisymmetrically onto the substrate or will create a splash, giving rise to usually undesired star-shaped patterns. In our experimental setup, drops are generated injecting low viscosity liquids falling under the action of gravity from a stainless steel hypodermic needle. The experimental observations using two high speed cameras operating simultaneously and placed perpendicularly to each other reveal that, initially, the drop deforms axisymmetrically, with A (T) the radius of the wetted area. For high enough values of the drop impact velocity, a thin sheet of liquid starts to be ejected from A (T) at a velocity Vjet > V for instants of time such that T >=Tc . If Vjet is above a certain threshold, which depends on the solid wetting properties as well as on the material properties of both the liquid and the atmospheric gas, the rim of the lamella dewets the solid to finally break into drops. Using Wagner's theory we demonstrate that A (T) =√{ 3 RVT } and our results also reveal that Tc We - 1 / 2 =(ρV2 R / σ) - 1 / 2 and Vjet We 1 / 4 .

  20. SMOOTHING ROTATION CURVES AND MASS PROFILES

    SciTech Connect

    Berrier, Joel C.; Sellwood, J. A.

    2015-02-01

    We show that spiral activity can erase pronounced features in disk galaxy rotation curves. We present simulations of growing disks, in which the added material has a physically motivated distribution, as well as other examples of physically less realistic accretion. In all cases, attempts to create unrealistic rotation curves were unsuccessful because spiral activity rapidly smoothed away features in the disk mass profile. The added material was redistributed radially by the spiral activity, which was itself provoked by the density feature. In the case of a ridge-like feature in the surface density profile, we show that two unstable spiral modes develop, and the associated angular momentum changes in horseshoe orbits remove particles from the ridge and spread them both inward and outward. This process rapidly erases the density feature from the disk. We also find that the lack of a feature when transitioning from disk to halo dominance in the rotation curves of disk galaxies, the so called ''disk-halo conspiracy'', could also be accounted for by this mechanism. We do not create perfectly exponential mass profiles in the disk, but suggest that this mechanism contributes to their creation.