INF2 -FORMIN THAT POLYMERIZES AND DEPOL YMERIZES ACTIN ON ENDOPLASMIC RETICULUM A Thesis Submitted to the Faculty in partial fulfillment of the requirements for the degree of cfnifi;s ·K. Barlowe, Ph.D. Dean of Graduate Studies Doctor of Philosophy In Biochemistry by Ekta Seth Chhabra DARTMOUTH COLLEGE Hanover, New Hampshire May 23rd ,2008 Examining Committee: • u» Henry N. Higgs, PhP - - 1 Duane A. Compton, Ph.D D~ R. Madden, Ph.D Jennifer Lippincott-Schwartz, Ph.D ...
casSAR Dugability of Q96DN0 | ERP27 | Endoplasmic reticulum resident protein 27 - Also known as ERP27_HUMAN, ERP27, C12orf46. Specifically binds unfolded proteins and may recruit protein disulfide isomerase PDIA3 to unfolded substrates (PubMed:16940051, PubMed:23192347). Binds protein substrates via a hydrophobic pocket in the C-terminal domain (PubMed:16940051, PubMed:23192347). May play a role in the unfolded stress response (PubMed:23192347). Interacts with PDIA3.
Implementation of dendritic cell- (DC-) based therapies in organ transplantation can reduce dependency on nonspecific immunosuppression. Despite extensive research, mechanisms of equipped DCs inducing transplant tolerance remain incomplete. Here, we applied RNA interference technique to inhibit CD80 and CD86 expression in host bone marrow-derived DCs. This approach could specifically and effectively knock down CD80 and CD86 expression. T cells primed by these DCs inhibited allogeneic responses. Administration of recipient DCs loaded with alloantigen after CD80 and CD86 blockade prolonged cardiac allograft survival. We also found a higher percentage of apoptotic T cells in lymph tissues and grafts than that detected in control group. In addition, these T cells expressed high expression of GRP78 than controls, indicating activation of unfolded protein responses. Upregulation of CHOP expression among these cells suggested that the endoplasmic reticulum stress (ERS) response switched to a proapoptotic
Title: Mif1: A Missing Link between the Unfolded Protein Response Pathway and ER-Associated Protein Degradation?. VOLUME: 2 ISSUE: 2. Author(s):Theo van Laar, Alex J. van der Eb and Carrol Terleth. Affiliation:MGC-Department ofRadiation Genetics and Chemical Mutagenesis, Leiden University MedicalCenter, P. O. Box 9503, 2300 RA Leiden, the Netherlands. Keywords:Eukaryotic cells, ER-Associated Protein Degradation, Alzheimers disease, protein disulfide isomerase (PDI), ER-lumenal part, UPR-independent functions, multi-membrane spanning ER, RING-domain, E3 Ubiquitin Ligase, ER-stress. Abstract: Eukaryotic cells have three different mechanisms to deal with the accumulation of unfolded proteins in the endoplasmic reticulum: (1) In cells in which unfolded polypeptides accumulate, translation initiation is inhibited to prevent further accumulation of unfolded proteins. (2) Expression of proteins involved in polypeptide folding is strongly enhanced by a process called the Unfolded Protein Response (UPR). ...
ER retention refers to proteins that are retained in the endoplasmic reticulum, or ER, after folding; these are known as ER resident proteins. Their localization to the ER often depends on certain sequences of amino acids located at the N-terminus or C-terminus. The classical ER retention signal is the C-terminal KDEL sequence for lumen bound proteins and KKXX for transmembrane localization. These signals allow for retrieval from the Golgi apparatus by ER retention receptors, effectively maintaining the protein in the ER.[1] Other mechanisms for ER retention are being studied but are not as well characterized as signal retention. ...
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Fig. 4. Hrd1p/Hrd3p cross-linking to Hmg2p did not require the presence of Ubc7p or Cue1p. (a) Hrd3p cross-linking to Hmg2p in the presence of either the hrd1Δ, ubc7Δ, orcue1Δ allele. The appropriate null alleles of each gene required for Hmg2p degradation were introduced into the strain coexpressing 1myc-Hmg2p and 3HA-Hrd3p. Cross-linking assay was performed as in Fig. 1. (b) Hrd1p cross-linking to Hmg2p in the presence of either the hrd1Δ, ubc7Δ, orcue1Δ allele. The appropriate null alleles of each gene required for Hmg2p degradation were introduced into the strain coexpressing 1myc-Hmg2p and 3HA-Hrd1p, and the cross-linking assay was performed. (c) Hrd3p function was required for Hrd1p cross-linking to Hmg2p under normal Hrd1p expression levels. Cells expressing 1myc-Hmg2p and 3HA-Hrd1p from its native promoter and coexpressing either the wild-type HRD3 allele (wt), the hrd3Δ allele, or the truncated hrd3 allele (hrd3357-833 ) were subjected to the cross-linking assay. (d) Expression ...
Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) is a type I endoplasmic reticulum transmembrane protein containing a stress-sensing domain facing the endoplasmic reticulum lumen and a cytosolic kinase domain. PERK is a major component of the unfolded protein response (UPR), which promotes the adaptation of cells to various forms of stress. PERK is activated in response to a variety of endoplasmic reticulum stresses implicated in numerous disease states. PERK regulates proliferation of beta cells during embryonic and neonatal development and is essential for viability of acinar cells in mouse exocrine pancreas, neither of which is associated with endoplasmic reticulum stress response. PERK is also required for endoplasmic reticulum functions including proinsulin trafficking and quality control in beta cells. Similarly, PERK modulates proliferation and differentiation of osteoblasts as well as secretion of type I collagen. PERK phosphorylates α subunit of the translation ...
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Ribophorins I and II, two transmembrane glycoproteins characteristic of the rough endoplasmic reticulum (ER) are thought to be part of the translocation apparatus for proteins made on membrane bound polysomes. To study the stoichiometry between ribophorins and membrane-bound ribosomes we have determined the RNA and ribophorin content in rat liver microsomes or in microsomal subfractions of different density (i.e., ribosome content). The specificity of antibodies against the ribophorins was demonstrated by Western blot analysis of rat liver rough microsomes separated by 2-dimensional gel electrophoresis. The ribophorin content of microsomal subfractions was determined by indirect immunoprecipitation and for ribophorin I by a radioimmune assay. In the latter assay a molar ratio of ribophorin I/ribosomes approaching one was calculated for total microsomes as well as in the gradient subfractions. We therefore suggest that ribophorins mediate the binding of ribosomes to endoplasmic reticulum ...
Oxidative Medicine and Cellular Longevity is a unique peer-reviewed, Open Access journal that publishes original research and review articles dealing with the cellular and molecular mechanisms of oxidative stress in the nervous system and related organ systems in relation to aging, immune function, vascular biology, metabolism, cellular survival and cellular longevity. Oxidative stress impacts almost all acute and chronic progressive disorders and on a cellular basis is intimately linked to aging, cardiovascular disease, cancer, immune function, metabolism and neurodegeneration. The journal fills a significant void in todays scientific literature and serves as an international forum for the scientific community worldwide to translate pioneering
Probable lectin that binds selectively to improperly folded lumenal proteins. May function in endoplasmic reticulum quality control and endoplasmic reticulum-associated degradation (ERAD) of both non-glycosylated proteins and glycoproteins.
In a previous study we reported the presence of a large conductance K+ channel in the membrane of endoplasmic reticulum (ER) from rat hepatocytes. The channel open probability (Po) appeared voltage dependent and reached to a minimum 0.2 at +50 mV. Channel activity in this case was found to be totally inhibited at ATP concentration 2.5 mM, glibenclamide 100 μM and tolbutamide 400 μM. Existing evidence indicates an impairment of endoplasmic reticulum functions in ER stress condition. Because ER potassium channels have been involved in several ER functions including cytoprotection, apoptosis and calcium homeostasis, a study was carried out to consider whether the ER potassium channel function is altered in a high fat diet model of ER stress. Male Wistar rats were made ER stress for 2 weeks with a high fat diet. Ion channel incorporation of ER stress model into the bilayer lipid membrane allowed the characterization of K+ channel. Our results indicate that the channel Po was significantly ...
ENCODES a protein that exhibits enzyme binding (ortholog); ubiquitin conjugating enzyme binding (ortholog); ubiquitin protein ligase activity (ortholog); INVOLVED IN proteasomal protein catabolic process (ortholog); proteasome-mediated ubiquitin-dependent protein catabolic process (ortholog); protein K48-linked ubiquitination (ortholog); PARTICIPATES IN Endoplasmic Reticulum-associated degradation pathway; ASSOCIATED WITH familial adult myoclonic epilepsy 3 (ortholog); FOUND IN endoplasmic reticulum (ortholog); integral component of endoplasmic reticulum membrane (ortholog); integral component of membrane (ortholog); INTERACTS WITH bis(2-ethylhexyl) phthalate; chromium(6+); ethanol
Substrate recognition component of a SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complex that mediates the ubiquitination and subsequent proteasomal degradation of target proteins. Involved in the endoplasmic reticulum-associated degradation pathway (ERAD) for misfolded lumenal proteins by recognizing and binding sugar chains on unfolded glycoproteins that are retrotranslocated into the cytosol and promoting their ubiquitination and subsequent degradation. Prevents formation of cytosolic aggregates of unfolded glycoproteins that have been retrotranslocated into the cytosol. Able to recognize and bind denatured glycoproteins, preferentially those of the high-mannose type (By similarity).
Cardiovascular disease constitutes a major and increasing health burden in developed countries. Although treatments have progressed, the development of novel treatments for patients with cardiovascular diseases remains a major research goal. The endoplasmic reticulum (ER) is the cellular organelle in which protein folding, calcium homeostasis, and lipid biosynthesis occur. Stimuli such as oxidative stress, ischemic insult, disturbances in calcium homeostasis, and enhanced expression of normal and/or folding-defective proteins lead to the accumulation of unfolded proteins, a condition referred to as ER stress. ER stress triggers the unfolded protein response (UPR) to maintain ER homeostasis. The UPR involves a group of signal transduction pathways that ameliorate the accumulation of unfolded protein by increasing ER-resident chaperones, inhibiting protein translation and accelerating the degradation of unfolded proteins. The UPR is initially an adaptive response but, if unresolved, can lead to apoptotic
The biogenesis of nascent proteins translocated into the calcium‐rich, oxidizing milieu of the endoplasmic reticulum (ER) lumen is assisted by a group of resident ER proteins that include molecular chaperones and folding enzymes. These specialized ER proteins are constitutively expressed in all cells, where they play a role in monitoring and assisting the maturation of normal proteins (Gething and Sambrook, 1992; Hendrick and Hartl, 1993) and are essential for proper steady‐state operations of the eukaryotic secretory pathway. Expression of mutant secretory pathway proteins or exposure of cells to agents that adversely affect ER protein folding and maturation all result in the accumulation of unfolded proteins in the ER, thereby activating an inter‐organelle signaling pathway linking the ER and nucleus. This response, termed the unfolded protein response (UPR), includes the coordinate transcriptional up‐regulation of ER chaperones and folding enzymes (Lee, 1992).. In yeast, an ER ...
There are many contact sites of ER-PM in different cell types. The function of ER-plasma membrane contact sites is similar to that of the mitochondria-ER junctions, since Ca2+ homeostasis and lipid synthesis and trafficking take place there. As mentioned above, Ca2+ regulation is crucial as it is also responsible for protein synthesis, folding, and signaling. In excitable cells, the global calcium signal is generated by the coupling of PM depolarization and ER calcium release. In non-excitable cells, calcium influx is controlled by detecting luminal ER Ca2+ levels. Research has showed that the PM-ER contact site is involved in non-vesicular lipid trafficking. We know that lipids are insoluble in water. So to transfer lipid from its synthesis sites to its desired work place, one must shield the lipid. In fact, couple families of lipid transfer protein (LTPs) that can perform this task have been found on the contact sites. One of them is oxysterol-binding protein (OSBP) related proteins(ORPS). The ...
Plant cells, like cells from other kingdoms, have the ability to self-destruct in a genetically controlled manner. This process is defined as Programmed Cell Death (PCD). PCD can be triggered by various stimuli in plants including by endoplasmic reticulum (ER) stress. Research in the past two decades discovered that disruption of protein homeostasis in the endoplasmic reticulum (ER) could cause ER stress, which when prolonged/unresolved leads cells into PCD. ER stress-induced PCD is part of several plant processes, for instance, drought and heat stress have been found to elicit ER stress-induced PCD. Despite the importance of ER stress-induced PCD in plants, its regulation remains largely unknown, when compared with its counterpart in animal cells. In mammalian cells, several pro-apoptotic proteases called caspases were found to play a crucial role in ER stress-induced PCD. Over the past decade, several key proteases with caspase-like enzymatic activity have been discovered in plants and implicated in
The endoplasmic reticulum is a major organelle in all eukaryotic cells which performs multiple functions including protein and lipid synthesis and sorting, drug metabolism, and Ca 2+ storage and release. The endoplasmic reticulum, and its specialized muscle counterpart the sarcoplasmic reticulum, is the largest and most extensive of Ca 2+ storage organelle in eukaryotic cells, often occupying in excess of 10% of the cell volume. There are three major components of Ca 2+ storage organelles which mediate their major functions: Ca 2+ uptake, mediated by pumps and exchangers; storage enhanced by luminal Ca 2+ binding proteins, and Ca 2+ mobilization mediated by specific ion channels. Ca 2+ mobilization from the endoplasmic reticulum plays a central role in Ca 2+ signaling. Through Ca 2+ release channels in its membrane, the pervading and plastic structure of the endoplasmic reticulum allows Ca 2+ release to be rapidly targeted to specific cytoplasmic sites across the whole cell. That several
Communication between organelles is essential to coordinate cellular functions and the cells response to physiological and pathological stimuli. Organellar communication occurs at membrane contact sites (MCSs), where the endoplasmic reticulum (ER) membrane is tethered to cellular organelle membranes by specific tether proteins and where lipid transfer proteins and cell signaling proteins are located. MCSs have many cellular functions and are the sites of lipid and ion transfer between organelles and generation of second messengers. This review discusses several aspects of MCSs in the context of lipid transfer, formation of lipid domains, generation of Ca2+ and cAMP second messengers, and regulation of ion transporters by lipids. ...
Misfolded proteins of the endoplasmic reticulum (ER) are targeted to the cytoplasm for proteasomal degradation. Key components of this process are ER membrane-bound ubiquitin ligases. These ligases associate with the cytoplasmic AAA-ATPase Cdc48p/p97, which is thought to support the release of malfolded proteins from the ER. Here, we characterize a yeast protein complex containing the ubiquitin ligase Hrd1p and the ER membrane proteins Hrd3p and Der1p. Hrd3p binds malfolded proteins in the ER lumen enabling their delivery to downstream components. Therefore, we propose that Hrd3p acts as a substrate recruitment factor for the Hrd1p ligase complex. Hrd3p function is also required for the association of Cdc48p with Hrd1p. Moreover, our data demonstrate that recruitment of Cdc48p depends on substrate processing by the Hrd1p ligase complex. Thus, the Hrd1p ligase complex unites substrate selection in the ER lumen and polyubiquitination in the cytoplasm and links these processes to the release of ER ...
A summary of the article is shown below:. Purpose: The aim of the study was to examine the effects of resveratrol upon hepatic endoplasmic reticulum stress (ERS) and insulin sensitivity in vivo and in vitro. Material and methods: C57BL/6J mice were fed a high-fat diet (HFD) for 8 weeks, and insulin resistance was evaluated by the intraperitoneal glucose tolerance test (IPGTT). Mice were then treated with resveratrol for 12 weeks and blood and liver samples collected. Blood biochemical indicators were determined by kits, liver protein expression was determined by western blot, and morphological changes were observed by histological staining. Palmitic acid (PA)-induced insulin-resistant HepG2 cells were established. Cells were exposed to 100, 50 or 20 μM resveratrol for 24 hrs, and proliferation/cytotoxicity was determined. Cells were divided into five groups: control, PA, PA + Rev (100 μM), PA + Rev (50 μM) and PA + Rev (20 μM) groups. After 24 hrs of treatment, cellular proteins were ...
Engagement of the TNF receptor family of death receptors, including TNF-R1, Fas, Trail-R1, and Trail-R2, with their cognate ligands leads to the recruitment and autoactivation of initiator procaspase-8 (Krammer, 2000). Recent studies implicate that caspase-8 substrates located at distinct cellular loci play key roles in mediating death receptor-induced apoptosis. For example, caspase-8 cleavage of the BH3-only molecule BID promotes mitochondrial release of cyt.c and Smac/Diablo (Yin et al., 1999; Li et al., 2002); cleavage of RIP prevents the activation of NF-κB survival responses (Lin et al., 1999); and cleavage of the cytolinker plectin is important for disassembly of microfilaments (Stegh et al., 2000). In this work, we investigated the consequence of caspase-8 cleavage of BAP31 at the ER by expressing the pro-apoptotic p20 cleavage fragment in cells using an adenovirus vector. This approach allowed us to isolate and delineate a predicted branch of the death receptor signaling cascade. ...
TY - JOUR. T1 - Chemical chaperones reduce ionizing radiation-induced endoplasmic reticulum stress and cell death in IEC-6 cells. AU - Lee, Eun Sang. AU - Lee, Hae June. AU - Lee, Yoon Jin. AU - Jeong, Jae Hoon. AU - Kang, Seong Man. AU - Lim, Young Bin. PY - 2014/7/25. Y1 - 2014/7/25. N2 - Radiotherapy, which is one of the most effective approaches to the treatment of various cancers, plays an important role in malignant cell eradication in the pelvic area and abdomen. However, it also generates some degree of intestinal injury. Apoptosis in the intestinal epithelium is the primary pathological factor that initiates radiation-induced intestinal injury, but the mechanism by which ionizing radiation (IR) induces apoptosis in the intestinal epithelium is not clearly understood. Recently, IR has been shown to induce endoplasmic reticulum (ER) stress, thereby activating the unfolded protein response (UPR) signaling pathway in intestinal epithelial cells. However, the consequences of the IR-induced ...
Obesity-induced endoplasmatic reticulum (ER) stress has been demonstrated to underlie the induction of obesity-induced JNK and NF-kappa B activation inflammatory responses, and generation of peripheral insulin resistance. On the other hand, exercise has been used as a crucial tool in obese and diabetic patients, and may reduce inflammatory pathway stimulation. However, the ability of exercise training to reverse endoplasmatic reticulum stress in adipose and hepatic tissue in obesity has not been investigated in the literature. Here, we demonstrate that exercise training ameliorates ER stress and insulin resistance in DIO-induced rats. Rats were fed with standard rodent chow (3,948 kcal kg(-1)) or high-fat diet (5,358 kcal kg(-1)) for 2 months. After that rats were submitted to swimming training (1 h per day, 5 days for week with 5% overload of the body weight for 8 weeks). Samples from epididymal fat and liver were obtained and western blot analysis was performed. Our results showed that ...
Ca2+ ions are important second messengers in many cellular signal transduction pathways. Compromised Ca2+ homeostasis and signaling have been linked to many human diseases, including muscle dysfunction and heart failure.1-5 Two principal sources provide Ca2+ to the cell: channels in the plasma membrane (PM) that allow external Ca2+ to enter the cell and internal stores sequestered in the endoplasmic reticulum (ER) or sarcoplasmic reticulum (SR) that release Ca2+. Junctional membrane complexes between PM and ER/SR are present in all excitable cells, providing effective mechanisms for cross-talk between Ca2+ channels/transporters in the PM and Ca2+ release channels in intracellular membranes.6-10 A central focus in cardiovascular research is to understand the basic mechanisms that underlie the control of Ca2+ signaling in the heart and to search for ways to correct the defective Ca2+ signaling process associated with arrhythmogenesis and heart failure.. In the heart, entry of extracellular Ca2+ ...
We have used proteolysis to examine the environment through which nascent secretory proteins are translocated across the membrane of the endoplasmic reticulum. After solubilization of rough microsomes with detergent, fragments comprised of the approximately 70 carboxyl-terminal amino acids of translocating nascent chains initiated and targeted in vivo were protected from digestion by added proteases. About 40 amino acids of nascent chains were protected from proteolysis by the ribosome; thus, membrane-derived components protect an additional 30 amino acids. Under conditions in which those 30 additional amino acids are protected, only a small set of integral membrane proteins remained associated with the ribosome. These proteins include the Sec61 complex previously identified as the core component of the membrane-bound protein translocation apparatus. These results support the concept of a translocation pore that makes intimate contact with the ribosome and thereby protects nascent chains from ...
The endoplasmic reticulum (ER) is a subcellular organelle where proteins are folded with the help of lumenal chaperones. Newly synthesized peptides enter the ER via the sec61 pore and are glycosylated. Correctly folded proteins are packaged into transport vesicles that shuttle them to the Golgi complex. Misfolded proteins are retained within the ER lumen in complex with molecular chaperones. Proteins that are terminally misfolded bind to BiP and are directed toward degradation through the proteasome in a process called ER-associated degradation (ERAD). Accumulation of misfolded proteins in the ER causes ER stress and activates a signaling pathway called the unfolded protein response (UPR). In certain severe situations, however, the protective mechanisms activated by the UPR are not sufficient to restore normal ER function and cells die by apoptosis ...
LIPID TRANSFER PROTEINS AND MEMBRANE CONTACT SITES IN HUMAN CANCER FEBRUARY 12, 2020: Presentation from Sima Lev about the lipid transfer proteins in cancer.
ATF6, a membrane-anchored transcription factor from the endoplasmic reticulum (ER) that modulates the cellular response to stress as an effector of the unfolded-protein response (UPR), is a key player in the development of tumors of different origin. reticulum (ER) can be particularly affected by the presence of mutations in secretory proteins or by dynamic changes in the cellular microenvironment, events which are often encountered in cancers. In the ER, these events are sensed by specific sensors, which in turn trigger select Rabbit Polyclonal to CPB2 signaling pathways, collectively named the unfolded-protein response (UPR) (1). The UPR is an adaptive response that allows the cells to either overcome the stress or promote cell death in the case of overwhelming burden (1). Three ER-resident proteins, namely, the protein kinase PKR-like ER kinase (PERK), the inositol-requiring protein 1 alpha (IRE1), and the activating transcription factor 6 alpha (ATF6), have been identified as the major ...
Being a major factory for protein synthesis, assembly, and export, the endoplasmic reticulum (ER) has a precise and robust ER quality control (ERQC) system monitoring its product line. However, when organisms are subjected to environmental stress, whether biotic or abiotic, the levels of misfolded proteins may overwhelm the ERQC system, tilting the balance between the capacity of and demand for ER quality control and resulting in a scenario termed ER stress. Intense or prolonged ER stress may cause damage to the ER as well as to other organelles, or even lead to cell death in extreme cases. To avoid such serious consequences, cells activate self-rescue programs to restore protein homeostasis in the ER, either through the enhancement of protein-folding and degradation competence or by alleviating the demands for such reactions. These are collectively called the unfolded protein response (UPR). Long investigated in mammalian cells and yeasts, the UPR is also of great interest to plant scientists. Among
TY - JOUR. T1 - LHS1 and SIL1 provide a lumenal function that is essential for protein translocation into the endoplasmic reticulum. AU - Tyson, John R. AU - Stirling, Colin J. PY - 2000. Y1 - 2000. N2 - Lhs1p is an Hsp70-related chaperone localized in the endoplasmic reticulum (ER) lumen. Δlhs1 mutant cells are viable but are constitutively induced for the unfolded protein response (UPR). Here, we demonstrate a severe growth defect in Δire1Δlhs1 double mutant cells in which the UPR can no longer be induced. In addition, we have identified a UPR- regulated gene, SIL1, whose overexpression is sufficient to suppress the Δire1Δlhs1 growth defect. SIL1 encodes an ER-localized protein that interacts directly with the ATPase domain of Kar2p (BiP), suggesting some role in modulating the activity of this vital chaperone. SIL1 is a non-essential gene but the Δlhs1Δsil1 double mutation is lethal and correlates with a complete block of protein translocation into the ER. We conclude that the ...
Standard treatment for advanced malignant pleural mesothelioma (MPM) is a cisplatin/pemetrexed (MTA) regimen; however, this is confronted by drug resistance. Proteotoxic stress in the endoplasmic reticulum (ER) is a hallmark of cancer and some rely on this stress signalling in response to cytotoxic chemotherapeutics. We hypothesise that ER stress and the adaptive unfolded protein response (UPR) play a role in chemotherapy resistance of MPM. In vitro three-dimensional (3D) and ex vivo organotypic culture were used to enrich a chemotherapy-resistant population and recapitulate an in vivo MPM microenvironment, respectively. Markers of ER stress, the UPR and apoptosis were assessed at mRNA and protein levels. Cell viability was determined based on acid phosphatase activity. MPM cells with de novo and/or acquired chemotherapy resistance displayed low ER stress, which rendered the cells hypersensitive to agents that induce ER stress and alter the UPR. Bortezomib, an FDA-approved proteasome inhibitor,
The endoplasmic reticulum (ER) is an intracellular organelle for protein folding, lipid synthesis and Ca²⁺ storage. It is also responsible for the transportation for most of the secretory and transmembrane proteins. When the protein load exceeds the ER folding capacity, the ER undergoes stress and activates a set of signaling cascades that is termed the unfolded protein response (UPR). The multifunctional GRP78 is the major ER molecular chaperone with protein folding abilities and the master regulator of the UPR, and recently has been shown that a subfraction of it is localized on the cell surface acting as a co-receptor for various signaling pathway activation. ❧ Traditionally GRP78 is regarded as protective against hypoxia and nutrient starvation prevalent in the microenvironment of solid tumors, thus, its role in the development of hematologic malignancies remains to be determined. In this thesis, elevated GRP78 expression was detected in leukemic blasts of adult patients, leukemia cell ...
Diabetes is intimately associated with cardiovascular complications. Much evidence highlighted the complex interplay between Endoplasmic Reticulum (ER) stress and oxidative stress in the pathogenesis of diabetes. Hemeoxygenase-1 (HO-1) induction was shown to protect against oxidative stress in diabetes; however the underlying molecular mechanisms have not yet been fully elucidated. We aim in this project to test the hypothesis that HO-1 induction will protect against high glucose-mediated ER stress and oxidative stress in endothelial cells and will enhance cell survival. Endothelial cells were cultured in physiological or high concentrations of glucose in the presence of cobalt protoporphyrin 1X (CoPP, HO-1 inducer), 4-phenylbutyrate (PBA, chemical chaperone to inhibit ER stress) or vehicle. Then, ER stress response was assessed (PCR, western blot). The productions of ROS (flow cytometer) and NO (Griess assay) were analysed. Also, apoptosis and caspase 3/7 activity were assessed. High glucose treatment
1.Radons,J. The human HSP70 family of chaperones: where do we stand? Cell Stress Chaperones 21, 379-404 (2016).[PubMed]. 2.Zuiderweg,E.R., Hightower,L.E., & Gestwicki,J.E. The remarkable multivalency of the Hsp70 chaperones. Cell Stress Chaperones 22, 173-189 (2017).[PubMed]. 3.Braakman,I. & Bulleid,N.J. Protein folding and modification in the mammalian endoplasmic reticulum. Annu. Rev. Biochem. 80, 71-99 (2011).[PubMed]. 4.Genereux,J.C. et al. Unfolded protein response-induced ERdj3 secretion links ER stress to extracellular proteostasis. EMBO J. 34, 4-19 (2015). [PubMed]. 5.Cook,K.L. et al. Endoplasmic reticulum stress protein GRP78 modulates lipid metabolism to control drug sensitivity and antitumor immunity in breast cancer. Cancer Res. 76, 5657-5670 (2016).[PubMed]. 6.Gonzales,P.A. et al. Large-scale proteomics and phosphoproteomics of urinary exosomes. J. Am. Soc. Nephrol. 20, 363-379 (2009).[PubMed]. 7.Prunotto,M. et al. Proteomic analysis of podocyte exosome-enriched fraction from normal ...
Protein targeting to the endoplasmic reticulum can be either co- or posttranslational and involves the binding of a hydrophobic signal sequence by delivery factors such as signal recognition particle or components of the TRC/GET pathway, respectively (1). Inefficient recognition and/or delivery of precursor proteins destined for the endoplasmic reticulum can lead to their cytosolic accumulation, resulting in toxicity such as that observed in neurodegenerative disorders such as prionopathies (2, 3). The disposal of such mislocalized proteins in mammalian cells has recently been shown to depend on the BAG6 complex comprised of the BAG6 protein together with TRC35 and UBL4A. The BAG6 complex recognizes mislocalized proteins, recruits the E2 conjugating enzyme, UbcH5, and an unidentified E3 ligase(s), and thereby selectively promotes the rapid ubiquitination and proteasomal degradation of these substrates (4). This role for the BAG6 complex in cytosolic quality control extends other studies showing ...
The majority of patients with pancreatic ductal adenocarcinoma (PDA) develop metastatic disease after resection of their primary tumor. We found that livers from patients and mice with PDA harbor single, disseminated cancer cells (DCCs) lacking expression of cytokeratin-19 (CK19) and major histocompatibility complex class I (MHCI). We created a mouse model to determine how these DCCs develop. Intra-portal injection of immunogenic PDA cells into pre-immunized mice seeded livers only with single, non-replicating DCCs that were CK19(-) and MHCI(-) The DCCs exhibited an endoplasmic reticulum (ER) stress response but, paradoxically lacked both inositol-requiring enzyme 1alpha activation and expression of the spliced form of transcription factor XBP1 (XBP1s). Inducible expression of XBP1s in DCCs, in combination with T cell-depletion, stimulated the outgrowth of macro-metastatic lesions that expressed CK19 and MHCI. Thus, unresolved ER stress enables DCCs to escape immunity and establish latent ...
The biogenesis of most membrane proteins is governed by specific interactions between the newly synthetized nascent polypeptide chain and the evolutionary conserved and essential insertases and translocases (1-3). Insertases and translocases recognize their substrate and lower the free-energy barrier for inserting and folding the polypeptide into cellular membranes (3, 4). This insertion and folding can occur cotranslationally as the polypeptide exits the ribosome or posttranslationally after the polypeptide has been released by the ribosome. The bacterial translocase SecYEG has a eukaryotic homolog, Sec61, in the endoplasmatic reticulum (1), whereas the bacterial insertase YidC has Oxa1 and Oxa2 homologs in mitochondria, Get1 in endoplasmatic reticulum, and Alb3 in chloroplasts (5-7). In Gram-negative bacteria, SecYEG folds α-helical membrane proteins into the inner membrane and translocates precursors of soluble periplasmic and β-barrel outer membrane proteins to the periplasm (1, 8). ...
The endoplasmic reticulum (ER) is an intracellular organelle for protein folding, lipid synthesis and Ca2+ storage. It also is responsible for transporting most secreted and transmembrane proteins to their proper cellular locations. ER undergoes stress when the protein load exceeds its folding capacity, and cellular signaling cascades are activated as unfolded protein response (UPR). GRP78 is a major chaperone assisting protein folding, as well as a master regulator of UPR signaling. In this thesis, we discovered that heterozygosity of Grp78 enhances energy expenditure through upregulation of mitochondria activity, and alleviate high fat diet (HFD)-induced obesity and type 2 diabetes in mouse. The latter is also achieved through increase in insulin sensitivity in the white adipose tissue (WAT) of HFD-fed Grp78+/- mice, with adaptive UPR improving ER folding capacity and quality control. This mechanism is validated through overexpression of the active form of ATF6, a transcription factor known to ...
Hypoxia is an important factor that contributes to tumour aggressiveness and correlates with poor prognosis and resistance to conventional therapy. Therefore, identifying hypoxic environments within tumours is extremely useful for understanding cancer biology and developing novel therapeutic strategies. Several studies have suggested that carbonic anhydrase 9 (CA9) is a reliable biomarker of hypoxia and a potential therapeutic target, while pimonidazole has been identified as an exogenous hypoxia marker. However, other studies have suggested that CA9 expression is not directly induced by hypoxia and it is not expressed in all types of tumours. Thus, in this study, we focused on endoplasmic reticulum disulphide oxidase 1α (ERO1α), a protein that localises in the endoplasmic reticulum and is involved in the formation of disulphide bonds in proteins, to determine whether it could serve as a potential tumour-hypoxia biomarker. Using quantitative real-time polymerase chain reaction, we analysed the mRNA
Apoptosis is essential for normal development and maintenance of homeostasis, and disruption of apoptotic pathways is associated with multiple disease states, including cancer. Although initially identified as central regulators of apoptosis at the level of mitochondria, an important role for BCL-2 proteins at the endoplasmic reticulum is now well established. Signaling pathways emanating from the endoplasmic reticulum (ER) are involved in apoptosis initiated by stimuli as diverse as ER stress, oncogene expression, death receptor (DR) ligation and oxidative stress, and the BCL-2 family is almost invariably implicated in the regulation of these pathways. This also includes Ca2+-mediated cross talk between ER and mitochondria during apoptosis, which contributes to the mitochondrial dynamics that support the core mitochondrial apoptosis pathway. In addition to the regulation of apoptosis, BCL-2 proteins at the ER also regulate autophagy, a survival pathway that limits metabolic stress, genomic instability
Endoplasmic reticulum (ER) stress is a common feature of Parkinsons disease (PD), and several PD-related genes are responsible for ER dysfunction. Recent studies suggested LRRK2-G2019S, a pathogenic mutation in the PD-associated gene LRRK2, cause ER dysfunction, and could thereby contribute to the development of PD. It remains unclear, however, how mutant LRRK2 influence ER stress to control cellular outcome. In this study, we identified the mechanism by which LRRK2-G2019S accelerates ER stress and cell death in astrocytes. To investigate changes in ER stress response genes, we treated LRRK2-wild type and LRRK2-G2019S astrocytes with tunicamycin, an ER stress-inducing agent, and performed gene expression profiling with microarrays. The XBP1 SUMOylation and PIAS1 ubiquitination were performed using immunoprecipitation assay. The effect of astrocyte to neuronal survival were assessed by astrocytes-neuron coculture and slice culture systems. To provide in vivo proof-of-concept of our approach, we measured
Cereal α-amylases (EC 3.2.1.1) are typical secretory proteins found in many plants. In germinating cereal seeds, these enzyme molecules are biosynthesized and secreted from the secretory tissues, the scutellar epithelium and the aleurone, to the starchy endosperm, which has undergone programmed cell death. Numerous α-amylase isoforms have been identified in cereals, but the predominant α-amylase isoform I-1 (AmyI-1) in rice (Oryza sativa) is a unique glycoprotein that bears N-linked oligosaccharide side chains (Hayashi et al., 1990; Terashima et al., 1994). The biosynthesis and secretion of AmyI-1 have been extensively investigated: mRNA translation on endoplasmic reticulum (ER) membrane-bound ribosomes, signal sequence-dependent translocation of the ER, core glycosylation in the ER lumen, vesicular transport to the Golgi apparatus, oligosaccharide modification to the complex type, and exocytosis all proceed according to the canonical secretory mechanism (Palade, 1975; Blobel, 1980; Kornfeld ...
Hypoxia activates all components of the unfolded protein response (UPR), a stress response initiated by the accumulation of unfolded proteins within the endoplasmic reticulum (ER). Our group and others have shown previously that the UPR, a hypoxia-inducible factor-independent signaling pathway, mediates cell survival during hypoxia and is required for tumor growth. Identifying new genes and pathways that are important for survival during ER stress may lead to the discovery of new targets in cancer therapy. Using the set of 4,728 homozygous diploid deletion mutants in budding yeast, Saccharomyces cerevisiae, we did a functional screen for genes that conferred resistance to ER stress-inducing agents. Deletion mutants in 56 genes showed increased sensitivity under ER stress conditions. Besides the classic UPR pathway and genes related to calcium homeostasis, we report that two additional pathways, including the SLT2 mitogen-activated protein kinase (MAPK) pathway and the osmosensing MAPK pathway, ...
Looking for online definition of Calcium Homeostasis Endoplasmic Reticulum Protein in the Medical Dictionary? Calcium Homeostasis Endoplasmic Reticulum Protein explanation free. What is Calcium Homeostasis Endoplasmic Reticulum Protein? Meaning of Calcium Homeostasis Endoplasmic Reticulum Protein medical term. What does Calcium Homeostasis Endoplasmic Reticulum Protein mean?
Our genetic screen for suppressors that restore defective ERAD in cdc48-10 cells identified Ssz1p. Being a member of the Hsp70 family, we considered the possibility that Ssz1p acted as a cytosolic chaperone that functions in ERAD by either activating or replacing the defective Cdc48p. The ability of Ssz1p to partially restore the impaired 6myc-Hmg2 degradation in ufd1-2 and npl4-1 mutants could have suggested that Ssz1p replaced the entire Cdc48p-Ufd1p-Npl4p complex in its role in ERAD. However, Ssz1p was not an essential ERAD factor and we could not detect any interaction of Ssz1p with the ERAD-M substrate 6myc-Hmg2. Moreover, Ssz1p is an unusual chaperone (Gautschi et al. 2001; Gautschi et al. 2002; Hundley et al. 2002; Shaner and Morano 2007), and therefore, we attributed its ability to correct ERAD to other functions of this Hsp70 member.. On the basis of the RAC-independent participation of Ssz1p in the PDR network, we examined whether other PDR members might be linked to ERAD. Indeed, ...
Transition zones are associated with the Golgi stacks. They are close to each other. This makes sense because the communication is more efficient. Vesicles dont need to travel long distances and the existence of the Golgi apparatus itself depends on a continuous process of vesicle incoming. It has been observed that a new transition zone led quickly to the nearby formation of a new Golgi stack. On the contrary, if a transition zone disappears, the associated Golgi cisternae are also lost. Transition zones can fuse with others and one transition zone can be split in two. Their associated Golgi stacks match this behavior. Vesicles budding from the transition zones are COPII coated vesicles ( COPII: coat protein II; Figure 1). Several proteins are involved in the formation of this COPII molecular framework: Sec16, Sar1 GTPases, Sec23/24 and Sec13/31. In this order, they are assembled at the cytosolic surface of the transition zone membranes. Transition zones are the more suitable environments for ...
TY - JOUR. T1 - Reconstitution of sterol-regulated endoplasmic reticulum-to-Golgi transport of SREBP-2 in insect cells by co-expression of mammalian SCAP and Insigs. AU - Dobrosotskaya, Irina Y.. AU - Goldstein, Joseph L.. AU - Brown, Michael S.. AU - Rawson, Robert B.. PY - 2003/9/12. Y1 - 2003/9/12. N2 - In mammalian cells, membrane-bound sterol regulatory element-binding proteins (SREBPs) are transported from ER to Golgi where they are processed proteolytically to generate soluble transcription factors that activate lipid synthesis. ER-to-Golgi transport requires SCAP, a sterol-regulated escort protein. In sterol-treated cells, the SCAP/SREBP complex binds to Insig-1 or Insig-2, which retains the complex in the ER, blocking SREBP processing and decreasing lipid synthesis. In Drosophila cells, the endogenous SCAP/SREBP complex is transported to Golgi, but transport is blocked by phosphatidylethanolamine instead of sterols. Here, we show that mammalian SREBP-2 is not transported to Golgi when ...
Since acetic acid inhibits the growth and fermentation ability of Saccharomyces cerevisiae, it is one of the practical hindrances to the efficient production of bioethanol from a lignocellulosic biomass. Although extensive information is available on yeast response to acetic acid stress, the involvement of endoplasmic reticulum (ER) and unfolded protein response (UPR) has not been addressed. We herein demonstrated that acetic acid causes ER stress and induces the UPR. The accumulation of misfolded proteins in the ER and activation of Ire1p and Hac1p, an ER-stress sensor and ER stress-responsive transcription factor, respectively, were induced by a treatment with acetic acid stress (| 0.2% v/v). Other monocarboxylic acids such as propionic acid and sorbic acid, but not lactic acid, also induced the UPR. Additionally, ire1∆ and hac1∆ cells were more sensitive to acetic acid than wild-type cells, indicating that activation of the Ire1p-Hac1p pathway is required for maximum tolerance to acetic acid.
TY - JOUR. T1 - An endoplasmic reticulum protein, Nogo-B, facilitates alcoholic liver disease through regulation of kupffer cell polarization. AU - Park, Jin Kyu. AU - Shao, Mingjie. AU - Kim, Moonyoung. AU - Baik, Soonkoo. AU - Cho, Meeyon. AU - Utsumi, Teruo. AU - Satoh, Ayano. AU - Ouyang, Xinsho. AU - Chung, Chuhan. AU - Iwakiri, Yasuko. PY - 2017/5/1. Y1 - 2017/5/1. N2 - Nogo-B (Reticulon 4B) is an endoplasmic reticulum (ER) resident protein that regulates ER structure and function. Because ER stress is known to induce M2 macrophage polarization, we examined whether Nogo-B regulates M1/M2 polarization of Kupffer cells and alters the pathogenesis of alcoholic liver disease (ALD). M1 and M2 phenotypes were assessed in relation to Nogo-B expression and disease severity in liver specimens from ALD patients (NCT01875211). Liver specimens from wild-type (WT) and Nogo-B knockout (KO) mice fed a control or Lieber-DeCarli ethanol liquid diet (5% ethanol) for 6 weeks were analyzed for liver injury ...
Tight repression of yeast endoplasmic reticulum stress sensor Ire1 by its N-terminal intrinsically disordered subdomainTight repression of yeast endoplasmic reticulum stress sensor Ire1 by its N-terminal intrinsically disordered subdomain ...
Human ER protein 44 ELISA Kit;Human ERp44 ELISA Kit;Human thioredoxin domain-containing protein 4 ELISA Kit;Human KIAA0573 ELISA Kit;Human TXNDC4 ELISA Kit;Human PDIA10 ELISA Kit;Human endoplasmic reticulum protein 44 ELISA Kit;Human endoplasmic reticulum resident protein 44 ELISA Kit;Human endoplasmic reticulum resident protein 44 kDa ELISA Kit;Human protein disulfide isomerase family A, member 10 ELISA Kit;Human thioredoxin domain containing 4 (endoplasmic reticulum) ELISA Kit ...
After axonal injury, chromatolysis (fragmentation of Nissl substance) occurs in both intrinsic neurons (whose processes are within the CNS) and extrinsic neurons (whose axons extend outside the CNS). Electron microscopy shows that chromatolysis involves fission of the rough endoplasmic reticulum. In intrinsic neurons (which do not regenerate axons) or in extrinsic neurons denied axon regeneration, chromatolysis is often accompanied by degranulation (loss of ribosomes from rough endoplasmic reticulum), disaggregation of polyribosomes and degradation of monoribosomes into dust-like particles. Ribosomes and rough endoplasmic reticulum may also be degraded in autophagic vacuoles by Ribophagy and Reticulophagy, respectively. In other words, chromatolysis is disruption of parts of the protein synthesis infrastructure. Whereas some neurons may show transient or no chromatolysis, severely injured neurons can remain chromatolytic and never again synthesise normal levels of protein; some may atrophy or die. What
Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures.. The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system.. The Golgi structures appear as stacks of platelet-vesicles which apparently ...
Obesity-mediated inflammation is a major cause of insulin resistance, and macrophages play an important role in this process. The 78-kDa glucose-regulated protein (GRP78) is a major endoplasmic reticulum chaperone that modulates unfolded protein response (UPR), and mice with GRP78 heterozygosity were resistant to diet-induced obesity. Here, we show that mice with macrophage-selective ablation of GRP78 (Lyz- GRP78(-/-)) are protected from skeletal muscle insulin resistance without changes in obesity compared with wild-type mice after 9 wk of high-fat diet. GRP78-deficient macrophages demonstrated adapted UPR with up-regulation of activating transcription factor (ATF)-4 and M2-polarization markers. Diet-induced adipose tissue inflammation was reduced, and bone marrow-derived macrophages from Lyz- GRP78(-/-) mice demonstrated a selective increase in IL-6 expression. Serum IL-13 levels were elevated by | 4-fold in Lyz- GRP78(-/-) mice, and IL-6 stimulated the myocyte expression of IL-13 and IL-13 receptor.
Propolis, a natural product collected from plants by honey bees, is commonly used in folk medicines. Endoplasmic reticulum (ER) stress is known to induce apoptosis through the induction of CCAAT/enhancer-binding protein homologous protein (CHOP). Here, we investigated whether ethanol extracts of pro …
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Fig. 1. Models of ER segregation in proliferating animal cells. In interphase (left panel), the peripheral ER forms an interconnected network that is contiguous with the outer membrane of the nuclear envelope. The outer nuclear membrane is biochemically similar to the peripheral ER membrane. By contrast, some integral membrane proteins are localized specifically to the inner nuclear membrane (yellow ovals) or to nuclear pores where the outer and inner nuclear membranes meet (red ovals). In one model of ER segregation (model a), the peripheral ER and the nuclear envelope undergo progressive vesiculation. By metaphase, the cell contains vesicles derived from the peripheral ER or outer nuclear membrane, and from the inner nuclear membrane or nuclear pore domains. Diffusion of these vesicles during metaphase and anaphase ensures the equal partition of ER elements. Another model (model b) predicts that the peripheral ER retains its integrity during mitosis. The nuclear envelope is absorbed into the ...
Membralin mutant mice manifest a severe and early-onset motor neuron disease with defects in endoplasmic reticulum-associated protein degradation.
GBRs (GABAB receptors; where GABA stands for γ-aminobutyric acid) are G-protein-coupled receptors that mediate slow synaptic inhibition in the brain and spinal cord. In vitro assays have previously demonstrated that these receptors are heterodimers assembled from two homologous subunits, GBR1 and GBR2, neither of which is capable of producing functional GBR on their own. We have used co-immunoprecipitation in combination with bioluminescence and fluorescence resonance energy transfer approaches in living cells to assess directly the interaction between GBR subunits and determine their subcellular localization. The results show that, in addition to forming heterodimers, GBR1 and GBR2 can associate as stable homodimers. Confocal microscopy indicates that, while GBR1/GBR1 homodimers are retained in the endoplasmic reticulum and endoplasmic reticulum-Golgi intermediate compartment, both GBR2/GBR2 homodimers and GBR1/GBR2 heterodimers are present at the plasma membrane. Although these observations ...
TY - JOUR. T1 - Nuclear pore disassembly from endoplasmic reticulum membranes promotes Ca2+ signalling competency. AU - Boulware, Michael J.. AU - Marchant, Jonathan S.. PY - 2008/6/15. Y1 - 2008/6/15. N2 - The functionality of the endoplasmic reticulum (ER) as a Ca2+ storage organelle is supported by families of Ca2+ pumps, buffers and channels that regulate Ca2+ fluxes between the ER lumen and cytosol. Although many studies have identified heterogeneities in Ca2+ fluxes throughout the ER, the question of how differential functionality of Ca2+ channels is regulated within proximal regions of the same organelle is unresolved. Here, we studied the in vivo dynamics of an ER subdomain known as annulate lamellae (AL), a cytoplasmic nucleoporin-containing organelle widely used in vitro to study the mechanics of nuclear envelope breakdown. We show that nuclear pore complexes (NPCs) within AL suppress local Ca+ signalling activity, an inhibitory influence relieved by heterogeneous dissociation of ...
Protein folding in the endoplasmic reticulum (ER) is error prone, and ER quality control (ERQC) processes ensure that only correctly folded proteins are exported from the ER. Glycoproteins can be retained in the ER by ERQC, and this retention contributes to multiple human diseases, termed ER storage diseases. UDP-glucose:glycoprotein glucosyltransferase (UGGT1) acts as a central component of glycoprotein ERQC, monoglucosylating deglucosylated N-glycans of incompletely folded glycoproteins and promoting subsequent reassociation with the lectin-like chaperones calreticulin and calnexin. The extent to which UGGT1 influences glycoprotein folding, however, has only been investigated for a few selected substrates. Using mouse embryonic fibroblasts lacking UGGT1 or those with UGGT1 complementation, we investigated the effect of monoglucosylation on the soluble/insoluble distribution of two misfolded alpha 1-antitrypsin (AAT) variants responsible for AAT deficiency disease: null Hong Kong (NHK) and Z ...
In an electron microsope study, the morphology of mature Paneth cells from the small intestine of adult rats is compared with that of differentiating Paneth cells from young rats 2 to 4 weeks old. All mature cells exhibit a marked polarity similar to that of other exocrine gland cells and contain a well developed endoplasmic reticulum, an elaborate Golgi complex, and numerous large secretory granules; they also possess an abundance of lysosomes. The most conspicuous occurrence in the process of differentiation is the development of the endoplasmic reticulum. The most immature Paneth cells possess an endoplasmic reticulum of the vesicular type, which, during maturation, is replaced by the characteristic lamellated ergastoplasm of the mature cell. At a certain stage of differentiation the cavities of the developing cisternae show numerous communications with the perinuclear space, suggesting an outgrowth of the ergastoplasm from the nuclear envelope. Furthermore, the cavities and the perinuclear ...
AIMS: In this study we investigated whether attenuation of endoplasmic reticulum stress (ER stress) could protect HepG2 cells from free fatty acid (FFA)-induced apoptosis. MAIN METHODS: Human liver cell line HepG2 cells were exposed to Sodium Palmitate (Pa) or Sodium Oleate (Ol). Apoptosis and ER stress of HepG2 cells were analyzed with flow cytometry, real-time RT-PCR and Western Blotting. An expression plasmid encoding for the ER chaperone immunoglobulin heavy chain-binding protein (Bip) was transfected into HepG2 cells to attenuate ER stress. Small interfering RNA siCHOP was used to knockdown the expression of C/EBP Homologous Protein (CHOP) in HepG2. KEY FINDINGS: Pa led to cytotoxicity and apoptosis in HepG2 cells in a dose-dependent pattern and also induced ER stress indicated by increased phosphorylation of eIF2alpha, upregulation of IRE1alpha and CHOP. Bip expression levels were slightly down regulated after Pa treatment. The unsaturated fatty acid, Ol, induced neither apoptosis nor ER stress in
TY - JOUR. T1 - Component of splicing factor SF3b plays a key role in translational control of polyribosomes on the endoplasmic reticulum. AU - Ueno, Tomonori. AU - Taga, Yuki. AU - Yoshimoto, Rei. AU - Mayeda, Akila. AU - Hattori, Shunji. AU - Ogawa-Goto, Kiyoko. PY - 2019/5/7. Y1 - 2019/5/7. N2 - One of the morphological hallmarks of terminally differentiated secretory cells is highly proliferated membrane of the rough endoplasmic reticulum (ER), but the molecular basis for the high rate of protein biosynthesis in these cells remains poorly documented. An important aspect of ER translational control is the molecular mechanism that supports efficient use of targeted mRNAs in polyribosomes. Here, we identify an enhancement system for ER translation promoted by p180, an integral ER membrane protein we previously reported as an essential factor for the assembly of ER polyribosomes. We provide evidence that association of target mRNAs with p180 is critical for efficient translation, and that SF3b4, ...
Despite the relevance of the eukaryotic endoplasmic reticulum (ER)-stress response as an integrator of multiple stress signals into an adaptive response, knowledge about these ER-mediated cytoprotective pathways in soybean (Glycine max) is lacking. Here, we searched for genes involved in the highly conserved unfolded protein response (UPR) and ER stress-induced plant-specific cell death signaling pathways in the soybean genome. Previously characterized Arabidopsis UPR genes were used as prototypes for the identification of the soybean orthologs and the in silico assembly of the UPR in soybean, using eggNOG v4.0 software. Functional studies were also conducted by analyzing the transcriptional activity of soybean UPR transducers. As a result of this search, we have provided a complete profile of soybean UPR genes with significant predicted protein similarities to A. thaliana UPR-associated proteins. Both arms of the plant UPR were further examined functionally, and evidence is presented that the soybean
Endoplasmic reticulum (ER)-associated degradation (ERAD) is a quality control mechanism that allows for targeted degradation of proteins in the ER. Zhou et al. found that a particular protein complex in ERAD, Sel1L-Hrd1, regulates the dynamics of another organelle, the mitochondrion, by altering ER-mitochondria contacts. Three-dimensional high-resolution imaging in brown adipocytes from cold-challenged mice revealed that defective ERAD led to the formation of enlarged and abnormally shaped mitochondria with perforating ER tubules. The authors explored the consequences of ERAD deficiency on mitochondrial function and thermogenesis, which provides insights into ERADmediated ER-mitochondrial cross-talk and advances our understanding of the physiological importance of interorganelle contact.. Science, this issue p. 54 ...
This work shows that the ubiquitous translocon complex in the endoplasmic reticulum membrane may act as a Ca2+ leak channel. The complex is not as tight as previously thought. Heritage and Wonderlin demonstrated that permeability of small polar molecules increased in cells treated with puromycin (Heritage and Wonderlin, 2001). Recently, it has been shown that the permeability of the ER to small polar molecules is coupled to translation (Roy and Wonderlin, 2003). In an initial study, we measured the effect of puromycin on the Ca2+ permeability of the ER membrane in mouse acinar pancreatic cells (Lomax et al., 2002). In the present work, we demonstrate that puromycin acts on the translocon to induce a Ca2+ leak in LNCaP cells and also that a physiological calcium leak through the translocon is possible at the end of termination when the ribosome is still in place. Puromycin is a potent translation inhibitor, specifically blocking the ribosome on the translocon and clearing the nascent peptide ...
Protein trafficking from the endoplasmic reticulum (ER) to the Golgi apparatus involves specific uptake into coat protein complex II (COPII)-coated vesicles of secretory and of vesicle targeting (v-SNARE) proteins. Here, two ER to Golgi v-SNAREs, Bet1p and Bos1p, were shown to interact specifically with Sar1p, Sec23p, and Sec24p, components of the COPII coat, in a guanine nucleotide-dependent fashion. Other v-SNAREs, Sec22p and Ykt6p, might interact more weakly with the COPII coat or interact indirectly by binding to Bet1p or Bos1p. The data suggest that transmembrane proteins can be taken up into COPII vesicles by direct interactions with the coat proteins and may play a structural role in the assembly of the COPII coat complex. ...
Antibodies for proteins involved in negative regulation of transcription from RNA polymerase II promoter in response to endoplasmic reticulum stress pathways, according to their Panther/Gene Ontology Classification
A growing epidemic of obesity and inflammatory bowel disease is threatening the health of millions of people around the world. Recent studies have established that these diseases are associated with systemic chronic inflammation and/or disrupted endoplasmic reticulum (ER) homeostasis. However, the role of inflammation and ER homeostasis in health and disease is not well understood. In this dissertation, I elucidate the physiological role of inflammasome, TLR signaling and ER associated degradation in various metabolic diseases. First, I show (Sun et al. Diabetes 2012) that the onset of obesity associated hyperglycemia and hyperinsulinemia coincides with the activation of the inflammasome in white adipose tissue. But unexpectedly, the ATP-P2X7 signaling axis, a well-known inflammasome-activating pathway, does not mediate the inflammasome activation. The nature of the inflammasome-activating danger signal(s) in adipose tissue in obesity remains to be characterized. Second, we report (Ji and Sun et ...
Several studies have correlated ER stress with myocardial damage. For example, the ER stress response is activated in the hearts of transgenic mice that overexpress monocyte chemoattractant protein-1 and develop heart failure,36 suggesting that in this model, the proapoptotic phase of ER stress contributes to the loss of myocardium associated with failure. In further support of a role for ER stress in heart failure is the finding that transgenic overexpression of a mutant KDEL receptor, an ER protein that facilitates ER protein targeting, activates the ER stress response in mouse hearts and causes dilated cardiomyopathy.69 Also, overexpression of the ER stress response gene product p53-upregulated modulator of apoptosis (PUMA) contributes to ER stress-mediated apoptosis in cultured cardiomyocytes70 and targeted deletion of PUMA in mouse hearts attenuates cardiomyocyte death during ex vivo I/R.71. In contrast to the studies cited above, other studies suggest that ER stress might protect the ...
The SHERP genes are found as a tandem pair within the differentially regulated LmcDNA16 locus of Leishmania major. The SHERP gene product (Small Hydrophilic Endoplasmic Reticulum-associated Protein) is unusual in its small size (6.2kDa), its acidic pI (4.6) and its exclusive, high-level expression ( 100000 copies per cell) in infective non-replicative parasite stages. No homologues have been found to date. Secondary-structure predictions suggest that SHERP contains an amphiphilic a-helix that is presumably involved in protein-protein interactions. SHERP has been localized to the endoplasmic reticulum as well as to the outer mitochondrial membrane in both wild-type and over-expressing parasites. Given the absence of an N-terminal signal sequence, transmembrane-spanning domains or detectable post-translational modifications, it is likely that this hydrophilic molecule is a peripheral membrane protein on the cytosolic face of intracellular membranes. This weak membrane association has been ...
Calcium (Ca2+) is a fundamental regulator of cell signaling and function. Thapsigargin (Tg) blocks the sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA), disrupts Ca2+ homeostasis, and causes cell death. However, the exact mechanisms whereby SERCA-inhibition induces cell death are incompletely understood. Here, we report that low (0.1 μM) concentrations of Tg and Tg analogs with various long-chain substitutions at the O(8) position extensively inhibit SERCA1a-mediated Ca2+ transport. We also found that in both prostate and breast cancer cells, exposure to Tg or Tg analogs for 1 day caused extensive drainage of the ER Ca2+ stores. This Ca2+ depletion was followed by markedly reduced cell proliferation rates and morphological changes that developed over 2-4 days and culminated in cell death. Interestingly, these changes were not accompanied by bulk increases in cytosolic Ca2+ levels. Moreover, knockdown of two key store-operated Ca2+ entry (SOCE) components, Orai1 and STIM1, did not reduce Tg ...
PhD Project - Characterisation of cell death pathways upon activation of the endoplasmic reticulum stress sensor IRE1alpha at Durham University, listed on FindAPhD.com
def: A protein complex that is located in the endoplasmic reticulum and is composed of chaperone proteins, including BiP, GRP94; CaBP1, protein disulfide isomerase (PDI), ERdj3, cyclophilin B, ERp72, GRP170, UDP-glucosyltransferase, and SDF2-L1. [PMID:12475965 ...
TY - JOUR. T1 - Role of the plant-specific endoplasmic reticulum stress-inducible gene TIN1 in the formation of pollen surface structure in Arabidopsis thaliana. AU - Iwata, Yuji. AU - Nishino, Tsuneyo. AU - Iwano, Megumi. AU - Takayama, Seiji. AU - Koizumi, Nozomu. N1 - KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: We would like to thank GABI-Kat and TAIR for the T-DNA insertion mutant and the gene annotation data, respectively. This work was supported by Ministry of Education, Culture, Sports, Science, and Technology of Japan, Grant-in-Aid for Scientific Research 20380188 to N.K.. PY - 2012. Y1 - 2012. N2 - Accumulation of unfolded proteins in the endoplasmic reticulum (ER) of eukaryotic cells triggers the transcriptional activation of ER-resident molecular chaperones and folding enzymes to maintain cellular homeostasis. This process is known as the ER stress response or the unfolded protein response. We have identified tunicamycin induced 1 (TIN1), a plant-specific ER ...
Apoptotic DNA fragmentation may be a cooperative activity between caspase-activated deoxyribonuclease and the poly(ADP-ribose) polymerase-regulated DNAS1L3, an endoplasmic reticulum-localized endonucleasethat translocates to the nucleus during apoptosis. Journal of Biological Chemistry, Vol.288, No.5 (2013): 3460-3468. Errami, Y., Naura, A.S., Kim, H., Ju, J., Suzuki, Y., El-Bahrawy, A.H., Ghonim, M.A., Hemeida, R.A., Mansy, M.S., Zhang, J., Xu, M., Smulson, M.E., Hassan Brim, Boulares, A.H.. ...
Apoptotic DNA fragmentation may be a cooperative activity between caspase-activated deoxyribonuclease and the poly(ADP-ribose) polymerase-regulated DNAS1L3, an endoplasmic reticulum-localized endonucleasethat translocates to the nucleus during apoptosis. Journal of Biological Chemistry, Vol.288, No.5 (2013): 3460-3468. Errami, Y., Naura, A.S., Kim, H., Ju, J., Suzuki, Y., El-Bahrawy, A.H., Ghonim, M.A., Hemeida, R.A., Mansy, M.S., Zhang, J., Xu, M., Smulson, M.E., Hassan Brim, Boulares, A.H.. ...