scholarly journals Endoplasmic reticulum stress activates SRC, relocating chaperones to the cell surface where GRP78/CD109 blocks TGF-β signaling

2018 ◽  
Vol 115 (18) ◽  
pp. E4245-E4254 ◽  
Author(s):  
Yuan-Li Tsai ◽  
Dat P. Ha ◽  
He Zhao ◽  
Anthony J. Carlos ◽  
Shan Wei ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Er Stress ◽  
Paradigm Shift ◽  
Retrograde Transport ◽  
Suppressor Effect ◽  
Cell Surface Grp78 ◽  
Β Receptor ◽  
Kdel Receptor ◽  
Tumor Suppressor Effect

The discovery that endoplasmic reticulum (ER) luminal chaperones such as GRP78/BiP can escape to the cell surface upon ER stress where they regulate cell signaling, proliferation, apoptosis, and immunity represents a paradigm shift. Toward deciphering the mechanisms, we report here that, upon ER stress, IRE1α binds to and triggers tyrosine kinase SRC activation, leading to ASAP1 phosphorylation and Golgi accumulation of ASAP1 and Arf1-GTP, resulting in KDEL receptor dispersion from the Golgi and suppression of retrograde transport. At the cell surface, GRP78 binds to and acts in concert with a glycosylphosphatidylinositol-anchored protein, CD109, in blocking TGF-β signaling by promoting the routing of the TGF-β receptor to the caveolae, thereby disrupting its binding to and activation of Smad2. Collectively, we uncover a SRC-mediated signaling cascade that leads to the relocalization of ER chaperones to the cell surface and a mechanism whereby GRP78 counteracts the tumor-suppressor effect of TGF-β.

scholarly journals Prohibitin: A Novel Molecular Player in KDEL Receptor Signalling

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Monica Giannotta ◽  
Giorgia Fragassi ◽  
Antonio Tamburro ◽  
Capone Vanessa ◽  
Alberto Luini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Membrane Trafficking ◽  
Transmembrane Domain ◽  
Cell Cycle Control ◽  
Retrograde Transport ◽  
Multifunctional Protein ◽  
G Protein Coupled ◽  
Kdel Receptor ◽  
Prohibitin 1

The KDEL receptor (KDELR) is a seven-transmembrane-domain protein involved in retrograde transport of protein chaperones from the Golgi complex to the endoplasmic reticulum. Our recent findings have shown that the Golgi-localised KDELR acts as a functional G-protein-coupled receptor by binding to and activating Gs and Gq. These G proteins induce activation of PKA and Src and regulate retrograde and anterograde Golgi trafficking. Here we used an integrated coimmunoprecipitation and mass spectrometry approach to identify prohibitin-1 (PHB) as a KDELR interactor. PHB is a multifunctional protein that is involved in signal transduction, cell-cycle control, and stabilisation of mitochondrial proteins. We provide evidence that depletion of PHB induces intense membrane-trafficking activity at the ER–Golgi interface, as revealed by formation of GM130-positive Golgi tubules, and recruitment of p115,β-COP, and GBF1 to the Golgi complex. There is also massive recruitment of SEC31 to endoplasmic-reticulum exit sites. Furthermore, absence of PHB decreases the levels of the Golgi-localised KDELR, thus preventing KDELR-dependent activation of Golgi-Src and inhibiting Golgi-to-plasma-membrane transport of VSVG. We propose a model whereby in analogy to previous findings (e.g., the RAS-RAF signalling pathway), PHB can act as a signalling scaffold protein to assist in KDELR-dependent Src activation.

scholarly journals Activation of cell surface GRP78 decreases endoplasmic reticulum stress and neuronal death

2017 ◽  
Vol 24 (9) ◽  
pp. 1518-1529 ◽  
Author(s):  
Morgane Louessard ◽  
Isabelle Bardou ◽  
Eloïse Lemarchand ◽  
Audrey M Thiebaut ◽  
Jérôme Parcq ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Cell Surface ◽  
Neuronal Death ◽  
Cell Surface Grp78

scholarly journals Golgi enzymes do not cycle through the endoplasmic reticulum during protein secretion or mitosis

2017 ◽  
Vol 28 (1) ◽  
pp. 141-151 ◽  
Author(s):  
Julien Villeneuve ◽  
Juan Duran ◽  
Margherita Scarpa ◽  
Laia Bassaganyas ◽  
Josse Van Galen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Secretion ◽  
Retrograde Transport ◽  
Binding Domain ◽  
Invariant Chain ◽  
Golgi Membranes ◽  
Consensus View ◽  
Kdel Receptor ◽  
Fkbp Domain ◽  
In Cells

Golgi-specific sialyltransferase (ST) expressed as a chimera with the rapamycin-binding domain of mTOR, FRB, relocates to the endoplasmic reticulum (ER) in cells exposed to rapamycin that also express invariant chain (Ii)-FKBP in the ER. This result has been taken to indicate that Golgi-resident enzymes cycle to the ER constitutively. We show that ST-FRB is trapped in the ER even without Ii-FKBP upon rapamycin addition. This is because ER-Golgi–cycling FKBP proteins contain a C-terminal KDEL-like sequence, bind ST-FRB in the Golgi, and are transported together back to the ER by KDEL receptor–mediated retrograde transport. Moreover, depletion of KDEL receptor prevents trapping of ST-FRB in the ER by rapamycin. Thus ST-FRB cycles artificially by binding to FKBP domain–containing proteins. In addition, Golgi-specific O-linked glycosylation of a resident ER protein occurs only upon artificial fusion of Golgi membranes with ER. Together these findings support the consensus view that there is no appreciable mixing of Golgi-resident enzymes with ER under normal conditions.

scholarly journals Obesity-Linked Variants of Melanocortin-4 Receptor Are Misfolded in the Endoplasmic Reticulum and Can Be Rescued to the Cell Surface by a Chemical Chaperone

2010 ◽  
Vol 31 (4) ◽  
pp. 605-605
Author(s):  
Susana Granell ◽  
Sameer Mohammad ◽  
Ramanagouda Ramanagoudr-Bhojappa ◽  
Giulia Baldini
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Er Stress ◽  
Binding Protein ◽  
Intracellular Localization ◽  
Specific Inhibitor ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Chemical Chaperone ◽  
Melanocortin 4 Receptor

Abstract Melanocortin-4 receptor (MC4R) is a G protein-coupled receptor expressed in the brain where it controls food intake. Many obesity-linked MC4R variants are poorly expressed at the plasma membrane and are retained intracellularly. We have studied the intracellular localization of four obesity-linked MC4R variants, P78L, R165W, I316S, and I317T, in immortalized neurons. We find that these variants are all retained in the endoplasmic reticulum (ER), are ubiquitinated to a greater extent than the wild-type (wt) receptor, and induce ER stress with increased levels of ER chaperones as compared with wt-MC4R and appearance of CCAAT/enhancer-binding protein homologous protein. Expression of the X-box-binding-protein-1 with selective activation of a protective branch of the unfolded protein response did not have any effect on the cell surface expression of MC4R-I316S. Conversely, the pharmacological chaperone 4-phenyl butyric acid (PBA) increased the cell surface expression of wt-MC4R, MC4R-I316S, and I317T by more than 40%. PBA decreased ubiquitination of MC4R-I316S and prevented ER stress induced by expression of the mutant, suggesting that the drug functions to promote MC4R folding. MC4R-I316S rescued to the cell surface is functional, with a 52% increase in agonist-induced cAMP production, as compared with untreated cells. Also direct inhibition of wt-MC4R and MC4R-I316S ubiquitination by a specific inhibitor of the ubiquitin-activating enzyme 1 increased by approximately 40% the expression of the receptors at the cell surface, and the effects of PBA and ubiquitin-activating enzyme 1 were additive. These data offer a cell-based rationale that drugs that improve MC4R folding or decrease ER-associated degradation of the receptor may function to treat some forms of hereditary obesity.

scholarly journals Inhibition of Cardiomyocytes Hypertrophy by Resveratrol Is Associated with Amelioration of Endoplasmic Reticulum Stress

2016 ◽  
Vol 39 (2) ◽  
pp. 780-789 ◽  
Author(s):  
Yan Lin ◽  
Jingbin Zhu ◽  
Xiaojie Zhang ◽  
Jun Wang ◽  
Wei Xiao ◽  
...  
Keyword(s):  
Gene Expression ◽  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Protein Expression ◽  
Er Stress ◽  
Surface Area ◽  
Myocardial Cell ◽  
Control Group ◽  
Cell Surface Area ◽  
Transmission Electron

Background/Aims: Resveratrol (Res), a polyphenol antioxidant found in red wine, has been shown to play a cardioprotective role. This study was undertaken to investigate whether Res can protect the heart suffering from hypertrophy injuries induced by isoproterenol (ISO), and whether the protective effect is mediated by endoplasmic reticulum (ER) stress. Methods: Cardiomyocytes were randomly assigned to the control group, ISO group (100 nM ISO for 48 h), Res + ISO group (50 μM Res and 100 nM ISO for 48 h) and Res group (50 μM Res for 48h only). Hypertrophy was estimated by measuring the cell surface area and the atrial natriuretic peptide (ANP) gene expression. Apoptosis was measured using Hoechst 33258 staining and transmission electron microscopy. Protein expression of ER stress and apoptosis factors was analyzed using Western Blot analysis. Results: Res effectively suppress the cardiomyocytes hypertrophy and apoptosis induced by ISO, characterized by the reduction of the myocardial cell surface area, the ANP gene expression, the LDH and MDA leakage amount and the rate of cell apoptosis, while decrease of the protein expression of GRP78, GRP94 and CHOP, and reverse the expression of Bcl-2 and Bax. Conclusion: In summary, Res treatment effectively suppressed myocardial hypertrophy and apoptosis at least partially via inhibiting ER stress.

Abstract 18708: Vascular Dysfunction in Hyperhomocysteinemia: In vitro Evidence for Endoplasmic Reticulum Stress-mediated Calcium-activated Potassium Channel Dysfunction

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Wen-Tao Sun ◽  
Xiang-Chong Wang ◽  
Cheuk-Man Yu ◽  
Shun-Hay Pun ◽  
Qin Yang
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Cell Surface ◽  
Er Stress ◽  
Vascular Dysfunction ◽  
Cell Protein ◽  
Α Subunit ◽  
Whole Cell

Objectives: KCa channels play an important role in the control of vascular tone. Opening of IKCa and SKCa in endothelial cells underlies the classic EDHF pathway and promotes NO production. Smooth muscle BKCa provides a negative feedback mechanism opposing vasoconstriction and is an effector of NO and EDHF. Previous studies demonstrated homocysteine (Hcy), a risk factor for atherosclerosis, compromises NO and EDHF function, however, whether KCa is involved is poorly studied and the underlying mechanisms remain unknown. We studied the effect of Hcy on vascular KCa with the role of endoplasmic reticulum (ER) stress explored. Methods: In vitro studies were performed in porcine coronary arteries and primary cultured porcine coronary endothelial (PCECs) and smooth muscle cells (PCSMCs). IKCa and SKCa-, and BKCa-mediated relaxations were studied in endothelium-intact and -denuded arteries in a myograph. IKCa and SKCa currents in PCECs and BKCa current in PCSMCs were analyzed by whole-cell patch clamp and channel expressions were examined by western blot. Results: Hcy impairs the role of IKCa and SKCa, and BKCa in vasorelaxation. Relaxant responses to channel activators NS309 and NS1619 were attenuated and EDHF-type response was inhibited. Hcy suppressed IKCa and SKCa currents in PCECs and BKCa currents in PCSMCs. Inhibition of ER stress enhanced KCa currents and improved EDHF-type and channel activators-induced responses. Whole-cell protein levels of IKCa and SKCa remained unchanged in Hcy-exposed PCECs whereas IKCa and SKCa at cell surface were significantly decreased. Hcy lowered protein of β1 but not α subunit of BKCa in PCSMCs. The decrease in cell surface IKCa and SKCa and reduction of BKCa β1 were restored by ER stress inhibition. Further, inhibition of PERK increased BKCa β1 protein and enhanced BKCa current. Conclusion: ER stress mediates Hcy-induced vascular dysfunction through inhibition of KCa. Suppression of cell surface expression underlies ER stress-mediated IKCa and SKCa inhibition. Downregulation of BKCa β1 by PERK-ER stress pathway plays a key role in the loss of BKCa function. This study provides new mechanistic insights into the role of ER stress in vascular dysfunction. Supported by RGC GRF CUHK4774/12M & CUHK14118414, and NSFC 81200123.

scholarly journals Binding of Anti-GRP78 Autoantibodies to Cell Surface GRP78 Increases Tissue Factor Procoagulant Activity via the Release of Calcium from Endoplasmic Reticulum Stores

2010 ◽  
Vol 285 (37) ◽  
pp. 28912-28923 ◽  
Author(s):  
Ali A. Al-Hashimi ◽  
Jennifer Caldwell ◽  
Mario Gonzalez-Gronow ◽  
Salvatore V. Pizzo ◽  
Danya Aboumrad ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Surface ◽  
Tissue Factor ◽  
Procoagulant Activity ◽  
Cell Surface Grp78

scholarly journals Vaspin Is an Adipokine Ameliorating ER Stress in Obesity as a Ligand for Cell-Surface GRP78/MTJ-1 Complex

Diabetes ◽  
2012 ◽  
Vol 61 (11) ◽  
pp. 2823-2832 ◽  
Author(s):  
A. Nakatsuka ◽  
J. Wada ◽  
I. Iseda ◽  
S. Teshigawara ◽  
K. Higashio ◽  
...  
Keyword(s):  
Cell Surface ◽  
Er Stress ◽  
Cell Surface Grp78

scholarly journals Dilated Cardiomyopathy Caused by Aberrant Endoplasmic Reticulum Quality Control in Mutant KDEL Receptor Transgenic Mice

2004 ◽  
Vol 24 (18) ◽  
pp. 8007-8017 ◽  
Author(s):  
Hiromichi Hamada ◽  
Masashi Suzuki ◽  
Shigeki Yuasa ◽  
Naoya Mimura ◽  
Norihiro Shinozuka ◽  
...  
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Transgenic Mice ◽  
Er Stress ◽  
Dilated Cardiomyopathy ◽  
Protein Aggregates ◽  
Mutant Mice ◽  
Er Quality Control ◽  
Kdel Receptor

ABSTRACT Aberrant protein folding beyond the capacity of endoplasmic reticulum (ER) quality control leads to stress response in the ER. The Lys-Asp-Glu-Leu (KDEL) receptor, a retrieval receptor for ER chaperones in the early secretory pathway, contributes to ER quality control. To elucidate the function of the KDEL receptor in vivo, we established transgenic mice expressing a mutant KDEL receptor. We found that the mutant KDEL receptor sensitized cells to ER stress and that the mutant mice developed dilated cardiomyopathy. Ultrastructural analyses revealed expanded sarcoplasmic reticulums and protein aggregates that obstructed the adjacent transverse tubules of the mutant cardiomyocytes. Cardiomyocytes from the mutant mice were sensitive to ER stress when treated with tunicamycin and showed a functional defect in the L-type Ca2+ current. We observed ubiquitinated protein aggregates, enhanced expression of CHOP (a death-related transcriptional factor expressed upon ER stress), and apoptosis in the mutant hearts. These findings suggest that impairment of the KDEL receptor disturbs ER quality control, resulting in accumulation of misfolded proteins in the ER in an in vivo system, and that the dilated cardiomyopathy found in the mutant KDEL receptor transgenic mice is associated with ER stress.

scholarly journals Dissociation of Coatomer from Membranes Is Required for Brefeldin A–induced Transfer of Golgi Enzymes to the Endoplasmic Reticulum

1997 ◽  
Vol 137 (2) ◽  
pp. 319-333 ◽  
Author(s):  
Jochen Scheel ◽  
Rainer Pepperkok ◽  
Martin Lowe ◽  
Gareth Griffiths ◽  
Thomas E. Kreis
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Transport ◽  
Golgi Complex ◽  
Mammalian Cells ◽  
Brefeldin A ◽  
Retrograde Transport ◽  
Marker Proteins ◽  
Kdel Receptor

Addition of brefeldin A (BFA) to mammalian cells rapidly results in the removal of coatomer from membranes and subsequent delivery of Golgi enzymes to the endoplasmic reticulum (ER). Microinjected anti-EAGE (intact IgG or Fab-fragments), antibodies against the “EAGE”-peptide of β-COP, inhibit BFA-induced redistribution of β-COP in vivo and block transfer of resident proteins of the Golgi complex to the ER; tubulo-vesicular clusters accumulate and Golgi membrane proteins concentrate in cytoplasmic patches containing β-COP. These patches are devoid of marker proteins of the ER, the intermediate compartment (IC), and do not contain KDEL receptor. Interestingly, relocation of KDEL receptor to the IC, where it colocalizes with ERGIC53 and ts-O45-G, is not inhibited under these conditions. While no stacked Golgi cisternae remain in these injected cells, reassembly of stacks of Golgi cisternae following BFA wash-out is inhibited to only ∼50%. Mono- or divalent anti-EAGE stabilize binding of coatomer to membranes in vitro, at least as efficiently as GTPγS. Taken together these results suggest that enhanced binding of coatomer to membranes completely inhibits the BFA-induced retrograde transport of Golgi resident proteins to the ER, probably by inhibiting fusion of Golgi with ER membranes, but does not interfere with the disassembly of the stacked Golgi cisternae and recycling of KDEL receptor to the IC. These results confirm our previous results suggesting that COPI is involved in anterograde membrane transport from the ER/IC to the Golgi complex (Pepperkok et al., 1993), and corroborate that COPI regulates retrograde membrane transport between the Golgi complex and ER in mammalian cells.

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