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Du J, Zhang J, Xiang X, Xu D, Cui K, Mai K, Ai Q. Activation of farnesoid X receptor suppresses ER stress and inflammation via the YY1/NCK1/PERK pathway in large yellow croaker ( Larimichthys crocea). Front Nutr 2022; 9:1024631. [PMID: 36505250 PMCID: PMC9731767 DOI: 10.3389/fnut.2022.1024631] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 11/25/2022] Open
Abstract
Unfolded protein responses from endoplasmic reticulum (ER) stress have been implicated in inflammatory signaling. The vicious cycle of ER stress and inflammation makes regulation even more difficult. This study examined effects of farnesoid X receptor (FXR) in ER-stress regulation in large yellow croakers. The soybean-oil-diet-induced expression of ER stress markers was decreased in fish with FXR activated. In croaker macrophages, FXR activation or overexpression significantly reduced inflammation and ER stress caused by tunicamycin (TM), which was exacerbated by FXR knockdown. Further investigation showed that the TM-induced phosphorylation of PERK and EIF2α was inhibited by the overexpression of croaker FXR, and it was increased by FXR knockdown. Croaker NCK1 was then confirmed to be a regulator of PERK, and its expression in macrophages is increased by FXR overexpression and decreased by FXR knockdown. The promoter activity of croaker NCK1 was inhibited by yin-yang 1 (YY1). Furthermore, the results show that croaker FXR overexpression could suppress the P65-induced promoter activity of YY1 in HEK293t cells and decrease the TM-induced expression of yy1 in macrophages. These results indicate that FXR could suppress P65-induced yy1 expression and then increase NCK1 expression, thereby inhibiting the PERK pathway. This study may benefit the understanding of ER stress regulation in fish, demonstrating that FXR can be used in large yellow croakers as an effective target for regulating ER stress and inflammation.
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Affiliation(s)
- Jianlong Du
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Junzhi Zhang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xiaojun Xiang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Dan Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Kun Cui
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs), The Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China,Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China,*Correspondence: Qinghui Ai
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The Spliced Leader RNA Silencing (SLS) Pathway in Trypanosoma brucei Is Induced by Perturbations of Endoplasmic Reticulum, Golgi Complex, or Mitochondrial Protein Factors: Functional Analysis of SLS-Inducing Kinase PK3. mBio 2021; 12:e0260221. [PMID: 34844425 PMCID: PMC8630539 DOI: 10.1128/mbio.02602-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
In the parasite Trypanosoma brucei, the causative agent of human African sleeping sickness, all mRNAs are trans-spliced to generate a common 5′ exon derived from the spliced leader (SL) RNA. Perturbations of protein translocation across the endoplasmic reticulum (ER) induce the spliced leader RNA silencing (SLS) pathway. SLS activation is mediated by a serine-threonine kinase, PK3, which translocates from the cytosolic face of the ER to the nucleus, where it phosphorylates the TATA-binding protein TRF4, leading to the shutoff of SL RNA transcription, followed by induction of programmed cell death. Here, we demonstrate that SLS is also induced by depletion of the essential ER-resident chaperones BiP and calreticulin, ER oxidoreductin 1 (ERO1), and the Golgi complex-localized quiescin sulfhydryl oxidase (QSOX). Most strikingly, silencing of Rhomboid-like 1 (TIMRHOM1), involved in mitochondrial protein import, also induces SLS. The PK3 kinase, which integrates SLS signals, is modified by phosphorylation on multiple sites. To determine which of the phosphorylation events activate PK3, several individual mutations or their combination were generated. These mutations failed to completely eliminate the phosphorylation or translocation of the kinase to the nucleus. The structures of PK3 kinase and its ATP binding domain were therefore modeled. A conserved phenylalanine at position 771 was proposed to interact with ATP, and the PK3F771L mutation completely eliminated phosphorylation under SLS, suggesting that the activation involves most if not all of the phosphorylation sites. The study suggests that the SLS occurs broadly in response to failures in protein sorting, folding, or modification across multiple compartments.
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Abstract
The non-catalytic region of tyrosine kinase (Nck) family of adaptors, consisting of Nck1 and Nck2, contributes to selectivity and specificity in the flow of cellular information by recruiting components of signaling networks. Known to play key roles in cytoskeletal remodeling, Nck adaptors modulate host cell-pathogen interactions, immune cell receptor activation, cell adhesion and motility, and intercellular junctions in kidney podocytes. Genetic inactivation of both members of the Nck family results in embryonic lethality; however, viability of mice lacking either one of these adaptors suggests partial functional redundancy. In this Cell Science at a Glance and the accompanying poster, we highlight the molecular organization and functions of the Nck family, focusing on key interactions and pathways, regulation of cellular processes, development, homeostasis and pathogenesis, as well as emerging and non-redundant functions of Nck1 compared to those of Nck2. This article thus aims to provide a timely perspective on the biology of Nck adaptors and their potential as therapeutic targets.
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Affiliation(s)
- Briana C. Bywaters
- Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 7783, USA
| | - Gonzalo M. Rivera
- Department of Veterinary Pathobiology, Texas A&M University, College Station, TX 7783, USA
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Alfaidi M, Bhattarai U, Orr AW. Nck1, But Not Nck2, Mediates Disturbed Flow-Induced p21-Activated Kinase Activation and Endothelial Permeability. J Am Heart Assoc 2020; 9:e016099. [PMID: 32468886 PMCID: PMC7428973 DOI: 10.1161/jaha.120.016099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Background Alteration in hemodynamic shear stress at atheroprone sites promotes endothelial paracellular pore formation and permeability. The molecular mechanism remains unknown. Methods and Results We show that Nck (noncatalytic region of tyrosine kinase) deletion significantly ameliorates disturbed flow‐induced permeability, and selective isoform depletion suggests distinct signaling mechanisms. Only Nck1 deletion significantly reduces disturbed flow‐induced paracellular pore formation and permeability, whereas Nck2 depletion has no significant effects. Additionally, Nck1 re‐expression, but not Nck2, restores disturbed flow‐induced permeability in Nck1/2 knockout cells, confirming the noncompensating roles. In vivo, using the partial carotid ligation model of disturbed flow, Nck1 knockout prevented the increase in vascular permeability, as assessed by Evans blue and fluorescein isothiocyanate dextran extravasations and leakage of plasma fibrinogen into the vessel wall. Domain swap experiments mixing SH2 (phosphotyrosine binding) and SH3 (proline‐rich binding) domains between Nck1 and Nck2 showed a dispensable role for SH2 domains but a critical role for the Nck1 SH3 domains in rescuing disturbed flow‐induced endothelial permeability. Consistent with this, both Nck1 and Nck2 bind to platelet endothelial adhesion molecule‐1 (SH2 dependent) in response to shear stress, but only Nck1 ablation interferes with shear stress–induced PAK2 (p21‐activated kinase) membrane translocation and activation. A single point mutation into individual Nck1 SH3 domains suggests a role for the first domain of Nck1 in PAK recruitment to platelet endothelial cell adhesion molecule‐1 and activation in response to shear stress. Conclusions This work provides the first evidence that Nck1 but not the highly similar Nck2 plays a distinct role in disturbed flow‐induced vascular permeability by selective p21‐activated kinase activation.
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Affiliation(s)
- Mabruka Alfaidi
- Department of Pathology and Translational Pathobiology LSU Health-Shreveport LA
| | - Umesh Bhattarai
- Department of Molecular& Cellular Physiology LSU Health-Shreveport LA
| | - A Wayne Orr
- Department of Pathology and Translational Pathobiology LSU Health-Shreveport LA.,Department of Molecular& Cellular Physiology LSU Health-Shreveport LA.,Department of Cell Biology and Anatomy LSU Health-Shreveport LA
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5
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Johnson CN, Hashim MM, Bailey CA, Byrd JA, Kogut MH, Arsenault RJ. Feeding of yeast cell wall extracts during a necrotic enteritis challenge enhances cell growth, survival and immune signaling in the jejunum of broiler chickens. Poult Sci 2020; 99:2955-2966. [PMID: 32475430 PMCID: PMC7597693 DOI: 10.1016/j.psj.2020.03.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/30/2020] [Accepted: 03/04/2020] [Indexed: 11/13/2022] Open
Abstract
Necrotic enteritis (NE) is one of the most common and costly diseases in the modern broiler industry, having an estimated economic impact of $6 billion dollars annually. Increasing incidents of NE have resulted from restrictions on the use of antibiotic feed additives throughout the broiler industry. As such, finding effective antibiotic alternatives has become a priority. In this study, an experimental model of NE was used, comprising a commercial infectious bursal disease virus vaccine and Clostridium perfringens (C. perfringens) inoculation. Yeast cells wall (YCW) components, β-glucan (BG), and mannoproteins (MPTs) were evaluated for their effects on disease development. Chicken-specific immunometabolic kinome peptide arrays were used to measure differential phosphorylation between control (uninfected), challenged (infected), and challenged and treated birds in duodenal, jejunal, and ileal tissues. Treatment groups included crude YCW preparation, BG, MPT, or BG+MPT as feed additives. Data analysis revealed kinome profiles cluster predominantly by tissue, with duodenum showing the greatest relative signaling and jejunum showing the greatest response to treatment. BG, MPT, and BG+MPT cluster together, separate from controls and challenge birds in each tissue. Changes in signaling resulting from the treatments were observed in cell growth and survival responses as well as immune responses. None of the treatments of disease challenge returned the profiles to control-like. This is attributable to immune modulation and metabolic effects of the treatments generating distinct profiles from control. Importantly, all the treatments are distinct from the challenge group despite being challenged themselves. Only BG+MPT treatment had a significant effect on bird weight gain compared with the NE challenge group, and this treatment had the greatest impact on gut tissue signaling in all segments. The signaling changes elicited by BG+MPT during an NE challenge were increased cell growth and survival signaling, reducing cell death, apoptosis and innate inflammatory responses, and generating compensatory signaling to reduce disease severity.
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Affiliation(s)
- Casey N Johnson
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA
| | - Mohammed M Hashim
- Department of Poultry Science, Texas A&M University, College Station, TX 77843, USA
| | - Christopher A Bailey
- Department of Poultry Science, Texas A&M University, College Station, TX 77843, USA
| | - James A Byrd
- USDA - ARS, Southern Plains Agricultural Research Center, College Station, TX 77845, USA
| | - Michael H Kogut
- USDA - ARS, Southern Plains Agricultural Research Center, College Station, TX 77845, USA
| | - Ryan J Arsenault
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA.
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Wang Z, Qu Y, Zhuo X, Li J, Zou J, Fan L. Investigating the physiological responses of Pacific white shrimp Litopenaeus vannamei to acute cold-stress. PeerJ 2019; 7:e7381. [PMID: 31372323 PMCID: PMC6660825 DOI: 10.7717/peerj.7381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/29/2019] [Indexed: 11/20/2022] Open
Abstract
Background Litopenaeus vannamei is one of the most important aquaculture shrimps in the world and low temperatures present a serious challenge to its survival, growth, and distribution. Methods To investigate their physiological responses during acute cold-stress, L. vannamei were treated under acute cooling conditions from 28 to 13 °C with a cooling rate of 2.5 °C/2 h and were maintained at 13 °C for 12 h. Plasma metabolite concentrations, histological changes, and relative gene expression related to the unfolded protein response (UPR) pathway and apoptosis in the hepatopancreas and the hemocytes of L. vannamei were investigated. Results The results revealed that the concentrations of triglycerides, total cholesterol, and total protein in plasma reached their peaks at 23 °C, and then decreased to their minimum values at 13 °C for 12 h. The activity of alkaline phosphatase in the plasma decreased to its lowest level while the activity of alanine aminotransferase increased to its highest level at 13 °C for 12 h. The hepatic tubules became necrotic and the basement membranes were ruptured at 13 °C for 12 h. The gene expression related to UPR and apoptosis in the hepatopancreas and hemocytes was significantly altered by the decrease in the temperature. Discussion The results revealed that acute cold-stress caused histological damage in the hepatopancreas of L. vannamei, reducing its immunity. The three UPR pathways were involved in the process of acute cold-stress and the response of activating transcription factor 6 to UPR may be faster and more directthan the IRE1 and PERK pathways.
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Affiliation(s)
- Zhenlu Wang
- College of Marine Sciences, South China Agricultural University, Guangzhou, China.,Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, South China Agricultural University, Guangzhou, China
| | - Yuexin Qu
- College of Marine Sciences, South China Agricultural University, Guangzhou, China.,Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, South China Agricultural University, Guangzhou, China
| | - Xiaolei Zhuo
- Qingyuan North River Fishery Science Institute, Qingyuan, China
| | - Junyi Li
- College of Marine Sciences, South China Agricultural University, Guangzhou, China.,Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, South China Agricultural University, Guangzhou, China
| | - Jixing Zou
- College of Marine Sciences, South China Agricultural University, Guangzhou, China.,Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, South China Agricultural University, Guangzhou, China
| | - Lanfen Fan
- College of Marine Sciences, South China Agricultural University, Guangzhou, China.,Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, South China Agricultural University, Guangzhou, China
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7
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Chalmers F, Mogre S, Son J, Blazanin N, Glick AB. The multiple roles of the unfolded protein response regulator IRE1α in cancer. Mol Carcinog 2019; 58:1623-1630. [PMID: 31041814 DOI: 10.1002/mc.23031] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 04/15/2019] [Indexed: 01/09/2023]
Abstract
Cancer is associated with a number of conditions such as hypoxia, nutrient deprivation, cellular redox, and pH changes that result in accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) and trigger a stress response known as the unfolded protein response (UPR). The UPR is a conserved cellular survival mechanism mediated by the ER transmembrane proteins activating transcription factor 6, protein kinase-like endoplasmic reticulum kinase, and inositol-requiring enzyme 1α (IRE1α) that act to resolve ER stress and promote cell survival. IRE1α is a kinase/endoribonuclease (RNase) with multiple activities including unconventional splicing of the messenger RNA (mRNA) for the transcription factor X-Box Binding Protein 1 (XBP1), degradation of other mRNAs in a process called regulated IRE1α-dependent decay (RIDD) and activation of a pathway leading to c-Jun N-terminal kinase phosphorylation. Each of these outputs plays a role in the adaptive and cell death responses to ER stress. Many studies indicate an important role for XBP1 and RIDD functions in cancer and new studies suggest that these two functions of the IRE1α RNase can have opposing functions in the early and later stages of cancer pathogenesis. Finally, as more is learned about the context-dependent role of IRE1α in cancer development, specific small molecule inhibitors and activators of IRE1α could play an important role in counteracting the protective shield provided by ER stress signaling in cancer cells.
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Affiliation(s)
- Fiona Chalmers
- The Department of Veterinary and Biomedical Sciences, Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, Pennsylvania
| | - Saie Mogre
- The Department of Veterinary and Biomedical Sciences, Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, Pennsylvania
| | - Jeongin Son
- The Department of Veterinary and Biomedical Sciences, Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, Pennsylvania
| | - Nicholas Blazanin
- Division of Pharmacology and Toxicology, College of Pharmacy, Dell Pediatric Research Institute, University of Texas at Austin, Austin, Texas
| | - Adam B Glick
- The Department of Veterinary and Biomedical Sciences, Center for Molecular Toxicology and Carcinogenesis, The Pennsylvania State University, Pennsylvania
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Non-Structural Protein 2B of Human Rhinovirus 16 Activates Both PERK and ATF6 Rather Than IRE1 to Trigger ER Stress. Viruses 2019; 11:v11020133. [PMID: 30717233 PMCID: PMC6409610 DOI: 10.3390/v11020133] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/26/2019] [Accepted: 01/29/2019] [Indexed: 12/13/2022] Open
Abstract
To understand the underlying mechanisms of endoplasmic reticulum (ER) stress caused by human rhinovirus (HRV) 16 and non-structural transmembrane protein 2B, the expressions of ER chaperone glucose-regulated protein 78 (GRP78) and three signal transduction pathways, including protein kinase RNA-like ER kinase (PERK), activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1 (IRE1), were evaluated after HRV16 infection and 2B gene transfection. Our results showed that both HRV16 infection and 2B gene transfection increased the expression of ER chaperone GRP78, and induced phosphorylation of PERK and cleavage of ATF6 in a time-dependent manner. Our data also revealed that the HRV16 2B protein was localized to the ER membrane. However, both HRV16 infection and HRV16 2B gene transfection did not induce ER stress through the IRE1 pathway. Moreover, our results showed that apoptosis occurred in H1-HeLa cells infected with HRV16 or transfected with 2B gene accompanied with increased expression of CHOP and cleaved caspase-3. Taken together, non-structural protein 2B of HRV16 induced an ER stress response through the PERK and ATF6 pathways rather than the IRE1 pathway.
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Mugabo Y, Lim GE. Scaffold Proteins: From Coordinating Signaling Pathways to Metabolic Regulation. Endocrinology 2018; 159:3615-3630. [PMID: 30204866 PMCID: PMC6180900 DOI: 10.1210/en.2018-00705] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 09/05/2018] [Indexed: 01/13/2023]
Abstract
Among their pleiotropic functions, scaffold proteins are required for the accurate coordination of signaling pathways. It has only been within the past 10 years that their roles in glucose homeostasis and metabolism have emerged. It is well appreciated that changes in the expression or function of signaling effectors, such as receptors or kinases, can influence the development of chronic diseases such as diabetes and obesity. However, little is known regarding whether scaffolds have similar roles in the pathogenesis of metabolic diseases. In general, scaffolds are often underappreciated in the context of metabolism or metabolic diseases. In the present review, we discuss various scaffold proteins and their involvement in signaling pathways related to metabolism and metabolic diseases. The aims of the present review were to highlight the importance of scaffold proteins and to raise awareness of their physiological contributions. A thorough understanding of how scaffolds influence metabolism could aid in the discovery of novel therapeutic approaches to treat chronic conditions, such as diabetes, obesity, and cardiovascular disease, for which the incidence of all continue to increase at alarming rates.
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Affiliation(s)
- Yves Mugabo
- Cardiometabolic Axis, Centre de Recherche de Centre Hospitalier de l’Université de Montréal, Montreal, Quebec, Canada
- Montréal Diabetes Research Centre, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Gareth E Lim
- Cardiometabolic Axis, Centre de Recherche de Centre Hospitalier de l’Université de Montréal, Montreal, Quebec, Canada
- Montréal Diabetes Research Centre, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
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10
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Kefalas G, Jouvet N, Baldwin C, Estall JL, Larose L. Peptide-based sequestration of the adaptor protein Nck1 in pancreatic β cells enhances insulin biogenesis and protects against diabetogenic stresses. J Biol Chem 2018; 293:12516-12524. [PMID: 29941454 DOI: 10.1074/jbc.ra118.002728] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Revised: 06/16/2018] [Indexed: 01/14/2023] Open
Abstract
One feature of diabetes is the failure of pancreatic β cells to produce insulin, but the molecular mechanisms leading to this failure remain unclear. Increasing evidence supports a role for protein kinase R-like endoplasmic reticulum kinase (PERK) in the development and function of healthy pancreatic β cells. Previously, our group identified the adaptor protein Nck1 as a negative regulator of PERK. Indeed, we demonstrated that Nck1, by directly binding PERK autophosphorylated on Tyr561, limits PERK activation and signaling. Accordingly, we found that stable depletion of Nck1 in β cells promotes PERK activation and signaling, increases insulin biosynthesis, and improves cell viability in response to diabetes-related stresses. Herein, we explored the therapeutic potential of abrogating the interaction between Nck and PERK to improve β-cell function and survival. To do so, we designed and used a peptide containing the minimal PERK sequence involved in binding Nck1 conjugated to the cell-permeable protein transduction domain from the HIV protein TAT. In the current study, we confirm that the synthetic TAT-Tyr(P)561 phosphopeptide specifically binds the SH2 domain of Nck and prevents Nck interaction with PERK, thereby promoting basal PERK activation. Moreover, we report that treatment of β cells with TAT-Tyr(P)561 inhibits glucolipotoxicity-induced apoptosis, whereas it enhances insulin production and secretion. Taken together, our results support the potential of sequestering Nck using a synthetic peptide to enhance basal PERK activation and create more robust β cells.
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Affiliation(s)
- George Kefalas
- From the Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.,the Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada, and
| | - Nathalie Jouvet
- the Institut de Recherches Cliniques de Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Cindy Baldwin
- From the Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.,the Institut de Recherches Cliniques de Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Jennifer L Estall
- the Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada, and .,the Institut de Recherches Cliniques de Montreal, Montreal, Quebec H2W 1R7, Canada
| | - Louise Larose
- From the Research Institute of the McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada, .,the Division of Experimental Medicine, Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada, and
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11
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Chalmers F, van Lith M, Sweeney B, Cain K, Bulleid NJ. Inhibition of IRE1α-mediated XBP1 mRNA cleavage by XBP1 reveals a novel regulatory process during the unfolded protein response. Wellcome Open Res 2017; 2:36. [PMID: 29062910 PMCID: PMC5645705 DOI: 10.12688/wellcomeopenres.11764.2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2017] [Indexed: 01/23/2023] Open
Abstract
Background: The mammalian endoplasmic reticulum (ER) continuously adapts to the cellular secretory load by the activation of an unfolded protein response (UPR). This stress response results in expansion of the ER, upregulation of proteins involved in protein folding and degradation, and attenuation of protein synthesis. The response is orchestrated by three signalling pathways each activated by a specific signal transducer, either inositol requiring enzyme α (IRE1α), double-stranded RNA-activated protein kinase-like ER kinase (PERK) or activating transcription factor 6 (ATF6). Activation of IRE1α results in its oligomerisation, autophosphorylation and stimulation of its ribonuclease activity. The ribonuclease initiates the splicing of an intron from mRNA encoding the transcription factor, X-box binding protein 1 (XBP1), as well as degradation of specific mRNAs and microRNAs. Methods: To investigate the consequence of expression of exogenous XBP1, we generated a stable cell-line expressing spliced XBP1 mRNA under the control of an inducible promotor. Results: Following induction of expression, high levels of XBP1 protein were detected, which allowed upregulation of target genes in the absence of induction of the UPR. Remarkably under stress conditions, the expression of exogenous XBP1 repressed splicing of endogenous XBP1 mRNA without repressing the activation of PERK. Conclusions: These results illustrate that a feedback mechanism exists to attenuate Ire1α ribonuclease activity in the presence of XBP1.
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Affiliation(s)
- Fiona Chalmers
- Institute of Molecular, Cellular and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Marcel van Lith
- Institute of Molecular, Cellular and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK
| | | | | | - Neil J Bulleid
- Institute of Molecular, Cellular and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK
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12
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Chalmers F, van Lith M, Sweeney B, Cain K, Bulleid NJ. Inhibition of IRE1α-mediated XBP1 mRNA cleavage by XBP1 reveals a novel regulatory process during the unfolded protein response. Wellcome Open Res 2017. [PMID: 29062910 DOI: 10.12688/wellcomeopenres.11764.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Background: The mammalian endoplasmic reticulum (ER) continuously adapts to the cellular secretory load by the activation of an unfolded protein response (UPR). This stress response results in expansion of the ER, upregulation of proteins involved in protein folding and degradation, and attenuation of protein synthesis. The response is orchestrated by three signalling pathways each activated by a specific signal transducer, either inositol requiring enzyme α (IRE1α), double-stranded RNA-activated protein kinase-like ER kinase (PERK) or activating transcription factor 6 (ATF6). Activation of IRE1α results in its oligomerisation, autophosphorylation and stimulation of its ribonuclease activity. The ribonuclease initiates the splicing of an intron from mRNA encoding the transcription factor, X-box binding protein 1 (XBP1), as well as degradation of specific mRNAs and microRNAs. Methods: To investigate the consequence of expression of exogenous XBP1, we generated a stable cell-line expressing spliced XBP1 mRNA under the control of an inducible promotor. Results: Following induction of expression, high levels of XBP1 protein were detected, which allowed upregulation of target genes in the absence of induction of the UPR. Remarkably under stress conditions, the expression of exogenous XBP1 repressed splicing of endogenous XBP1 mRNA without repressing the activation of PERK. Conclusions: These results illustrate that a feedback mechanism exists to attenuate Ire1α ribonuclease activity in the presence of XBP1.
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Affiliation(s)
- Fiona Chalmers
- Institute of Molecular, Cellular and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Marcel van Lith
- Institute of Molecular, Cellular and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK
| | | | | | - Neil J Bulleid
- Institute of Molecular, Cellular and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK
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IRE1α links Nck1 deficiency to attenuated PTP1B expression in HepG2 cells. Cell Signal 2017; 36:79-90. [DOI: 10.1016/j.cellsig.2017.04.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 04/11/2017] [Accepted: 04/23/2017] [Indexed: 12/23/2022]
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14
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Salton GD, Laurino CCFC, Mega NO, Delgado-Cañedo A, Setterblad N, Carmagnat M, Xavier RM, Cirne-Lima E, Lenz G, Henriques JAP, Laurino JP. Deletion of eIF2β lysine stretches creates a dominant negative that affects the translation and proliferation in human cell line: A tool for arresting the cell growth. Cancer Biol Ther 2017; 18:560-570. [PMID: 28692326 DOI: 10.1080/15384047.2017.1345383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Eukaryote initiation factor 2 subunit β (eIF2β) plays a crucial role in regulation protein synthesis, which mediates the interaction of eIF2 with mRNA. eIF2β contains evolutionarily conserved polylysine stretches in amino-terminal region and a zinc finger motif in the carboxy-terminus. METHODS The gene eIF2β was cloned under tetracycline transcription control and the polylysine stretches were deleted by site-directed mutagenesis (eIF2βΔ3K). The plasmid was transfected into HEK 293 TetR cells. These cells were analyzed for their proliferative and translation capacities as well as cell death rate. Experiments were performed using gene reporter assays, western blotting, flow cytometry, cell sorting, cell proliferation assays and confocal immunofluorescence. RESULTS eIF2βΔ3K affected negatively the protein synthesis, cell proliferation and cell survival causing G2 cell cycle arrest and increased cell death, acting in a negative dominant manner against the native protein. Polylysine stretches are also essential for eIF2β translocated from the cytoplasm to the nucleus, accumulating in the nucleolus and eIF2βΔ3K did not make this translocation. DISCUSSION eIF2β is involved in the protein synthesis process and should act in nuclear processes as well. eIF2βΔ3K reduces cell proliferation and causes cell death. Since translation control is essential for normal cell function and survival, the development of drugs or molecules that inhibit translation has become of great interest in the scenario of proliferative disorders. In conclusion, our results suggest the dominant negative eIF2βΔ3K as a therapeutic strategy for the treatment of proliferative disorders and that eIF2β polylysine stretch domains are promising targets for this.
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Affiliation(s)
- Gabrielle Dias Salton
- a Post-Graduation Program in Cellular and Molecular Biology, Molecular Radiobiology Laboratory, Biotechnology Center , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil , Cryobiology Unit and Umbilical Cord Blood Bank, Hemotherapy Service , Hospital de Clínicas de Porto Alegre , Porto Alegre (RS) , Brazil
| | - Claudia Cilene Fernandes Correia Laurino
- b Molecular Biology for Auto-immune and Infectious Diseases Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil . Embriology and Cellular Differentiation Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre; Faculdade de Veterinária , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil . Faculdade Nossa Senhora de Fátima , Caxias do Sul (RS) , Brazil . Instituto Brasileiro de Saúde , Porto Alegre (RS) , Brazil
| | - Nicolás Oliveira Mega
- c Animal Biology Post-Graduation Program , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - Andrés Delgado-Cañedo
- d Biotechnology Research Center for Interdisciplinary Research , Universidade Federal do Pampa , São Gabriel (RS) , Brazil
| | - Niclas Setterblad
- e Imaging, Cell Selection and Genomics Platform , Institut Universitaire d'Hématologie, Hôpital Saint-Louis , Paris , France
| | - Maryvonnick Carmagnat
- f Immunology and Histocompatibility Laboratory AP-HP , INSERM UMRS 940, Institut Universitaire d'Hématologie , Paris , France
| | - Ricardo Machado Xavier
- g Molecular Biology for Auto-immune and Infectious Diseases Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - Elizabeth Cirne-Lima
- h Embriology and Cellular Differentiation Laboratory, Experimental Research Center, Hospital de Clínicas de Porto Alegre; Faculdade de Veterinária , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - Guido Lenz
- i Cell Signaling Laboratory, Biophysics Department, Biotechnology Center and Post-Graduation Program in Cellular and Molecular Biology , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) , Brazil
| | - João Antonio Pêgas Henriques
- j Molecular Radiobiology Laboratory, Biotechnology Center and Post-Graduation Program in Cellular and Molecular Biology , Universidade Federal do Rio Grande do Sul , Porto Alegre (RS) ; Biotechnology Institute , Universidade de Caxias do Sul , Caxias do Sul (RS) , Brazil
| | - Jomar Pereira Laurino
- k Biotechnology Institute , Universidade de Caxias do Sul, Caxias do Sul (RS) and Instituto Brasileiro de Saúde , Porto Alegre (RS) , Brazil
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Abstract
A broad definition of preconditioning is "the preparation for a subsequent action." Mounting evidence demonstrates that novel remote preconditioning paradigms, in which protective stimuli experienced locally can capacitate systemic tolerance and enhanced cell viability upon exposure to ensuing cellular insults, have been largely successful in the field of cardiovascular ischemia/reperfusion injury. To ensure successful protective preconditioning, some models (including the uterus) have been demonstrated to activate the unfolded protein response (UPR), which is a cellular stress response controlled at the level of the endoplasmic reticulum. However, in the context of remote preconditioning, activation of these intracellular molecular pathways must result in the extracellular transmission of adaptive signals to remote targets. In our recently published manuscript, we have described the activation of the UPR in the pregnant uterine myocyte to be associated with increased uterine myocyte quiescence and normal gestational length. We hypothesize that ubiquitous uterine gestational stresses experienced in every pregnancy, which have been demonstrated in other systems to activate the UPR, may induce a robust paracrine dissemination of a uterine secretome, for example, glucose-regulated protein 78, with preconditioning-like properties. Furthermore, we speculate that the gestational stress-induced uterine secretome acts to promote both local and systemic tolerance to the ensuing gestational insults, allowing for the maintenance of uterine quiescence. In this context, preterm labor may be the result of a pregnant uterus experiencing a stress it cannot accommodate or when it is unable to host an appropriate UPR resulting in insufficient preconditioning and a diminished local and systemic capacity to tolerate pregnancy-dependent increases in normal gestational stress. This is highly attractive from a clinical viewpoint as we ultimately aim to identify local and systemic adaptations that may serve as preconditioning stimuli for use as a strategy to restore appropriate preconditioning profiles to prolong uterine quiescence in pregnancy.
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Affiliation(s)
- Judith Ingles
- 1 Department of Physiology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA.,2 Department of Obstetrics and Gynecology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA
| | - Chandrashekara N Kyathanahalli
- 1 Department of Physiology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA.,2 Department of Obstetrics and Gynecology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA
| | - Pancharatnam Jeyasuria
- 1 Department of Physiology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA.,2 Department of Obstetrics and Gynecology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA.,3 Perinatal Research Initiative Wayne State University School of Medicine, Wane State University, Detroit, MI, USA
| | - Jennifer C Condon
- 1 Department of Physiology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA.,2 Department of Obstetrics and Gynecology, Wayne State University Perinatal Initiative, School of Medicine, Wayne State University, Detroit, MI, USA.,3 Perinatal Research Initiative Wayne State University School of Medicine, Wane State University, Detroit, MI, USA
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16
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Dusseault J, Li B, Haider N, Goyette MA, Côté JF, Larose L. Nck2 Deficiency in Mice Results in Increased Adiposity Associated With Adipocyte Hypertrophy and Enhanced Adipogenesis. Diabetes 2016; 65:2652-66. [PMID: 27325288 DOI: 10.2337/db15-1559] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 06/09/2016] [Indexed: 11/13/2022]
Abstract
Obesity results from an excessive expansion of white adipose tissue (WAT) from hypertrophy of preexisting adipocytes and enhancement of precursor differentiation into mature adipocytes. We report that Nck2-deficient mice display progressive increased adiposity associated with adipocyte hypertrophy. A negative relationship between the expression of Nck2 and WAT expansion was recapitulated in humans such that reduced Nck2 protein and mRNA levels in human visceral WAT significantly correlate with the degree of obesity. Accordingly, Nck2 deficiency promotes an adipogenic program that not only enhances adipocyte differentiation and lipid droplet formation but also results in dysfunctional elevated lipogenesis and lipolysis activities in mouse WAT as well as in stromal vascular fraction and 3T3-L1 preadipocytes. We provide strong evidence to support that through a mechanism involving primed PERK activation and signaling, Nck2 deficiency in adipocyte precursors is associated with enhanced adipogenesis in vitro and adiposity in vivo. Finally, in agreement with elevated circulating lipids, Nck2-deficient mice develop glucose intolerance, insulin resistance, and hepatic steatosis. Taken together, these findings reveal that Nck2 is a novel regulator of adiposity and suggest that Nck2 is important in limiting WAT expansion and dysfunction in mice and humans.
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Affiliation(s)
- Julie Dusseault
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, Quebec, Canada
| | - Bing Li
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, Quebec, Canada
| | - Nida Haider
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, Quebec, Canada
| | - Marie-Anne Goyette
- Institut de Recherches Cliniques de Montréal (Université de Montréal), Montreal, Quebec, Canada
| | - Jean-François Côté
- Institut de Recherches Cliniques de Montréal (Université de Montréal), Montreal, Quebec, Canada
| | - Louise Larose
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, Quebec, Canada
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17
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Wen L, Han F, Shi Y, Li X. Role of the Endoplasmic Reticulum Pathway in the Medial Prefrontal Cortex in Post-Traumatic Stress Disorder Model Rats. J Mol Neurosci 2016; 59:471-82. [PMID: 27112439 DOI: 10.1007/s12031-016-0755-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/08/2016] [Indexed: 10/21/2022]
Abstract
Previous studies revealed that patients with post-traumatic stress disorder (PTSD) have a smaller than normal medial prefrontal cortex (mPFC), and PTSD rats [single prolonged stress, (SPS)] have an increased mPFC neuron apoptosis, which are related to the severity of PTSD symptoms. Three signalling pathways [protein kinase RNA-like endoplasmic reticulum kinase (PERK), activating transcription factor 6 (ATF6), and inositol-requiring enzyme 1 (IRE1)] in the endoplasmic reticulum (ER) play a critical role in resisting apoptosis. The aim of this study was to investigate whether the three branches of ER signalling are involved in SPS-induced mPFC neuron apoptosis. We used transmission electron microscopy (TEM) to detect morphological changes in ER and fluorescence spectrophotometry to detect the concentration of intracellular calcium in mPFC. We used molecular biological techniques to detect the expression levels of three branch signalling pathways of ER: phosphorylated PERK (p-PERK)/phosphorylated eukaryotic translation initiation factor 2A (p-eIF2a), ATF6a/X-box binding protein 1 (XBP1), and IRE1a. In addition, the ER molecular chaperone 78-kDa glucose-regulated protein (GRP78) and the ER-related apoptosis factors caspase family and Bax also were examined. Apoptosis neurons were detected by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling. The results showed that the concentration of calcium in mPFC was increased in SPS rats. Using TEM, we found that mPFC neurons in SPS rats showed an expanded ER and chromatin margination. The increased expressions of p-PERK/p-eIF2a, ATF6a/XBP1, and IRE1 in response to SPS were also observed, although the degrees of increase were different. In addition, the protein and mRNA expression of GRP78 was increased in SPS rats; the upregulation of ER-related apoptosis factors and apoptosis neurons after SPS stimulation was observed. These results suggested that the three signalling pathways of unfolded protein response were involved in PTSD-induced, ER-dependent apoptosis in mPFC.
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Affiliation(s)
- Lili Wen
- PTSD Lab, Department of histology and embryology, Basic Medicine College, China Medical University, No.77 Puhe Road, Shenbei New Area, Shenyang, Liaoning province, China, 110122
| | - Fang Han
- PTSD Lab, Department of histology and embryology, Basic Medicine College, China Medical University, No.77 Puhe Road, Shenbei New Area, Shenyang, Liaoning province, China, 110122.
| | - Yuxiu Shi
- PTSD Lab, Department of histology and embryology, Basic Medicine College, China Medical University, No.77 Puhe Road, Shenbei New Area, Shenyang, Liaoning province, China, 110122
| | - Xiaoyan Li
- PTSD Lab, Department of histology and embryology, Basic Medicine College, China Medical University, No.77 Puhe Road, Shenbei New Area, Shenyang, Liaoning province, China, 110122
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18
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Yamani L, Li B, Larose L. Nck1 deficiency improves pancreatic β cell survival to diabetes-relevant stresses by modulating PERK activation and signaling. Cell Signal 2015; 27:2555-67. [DOI: 10.1016/j.cellsig.2015.09.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/18/2015] [Accepted: 09/28/2015] [Indexed: 12/11/2022]
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19
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Martin S, Lovat PE, Redfern CPF. Cell-type variation in stress responses as a consequence of manipulating GRP78 expression in neuroectodermal cells. J Cell Biochem 2015; 116:438-49. [PMID: 25336069 DOI: 10.1002/jcb.24996] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/14/2014] [Indexed: 12/31/2022]
Abstract
Glucose-regulated protein 78 (GRP78) is a stress sensor which interacts with unfolded protein response (UPR) activators in the endoplasmic reticulum (ER). The aim of this study was to test the hypothesis that GRP78 has distinct functional roles in mediating the effects of ER stress in neuroblastoma compared to other neuroectodermal cancer types. GRP78 was knocked down or overexpressed in neuroectodermal tumor cell lines. Protein and transcript expression were measured using Western blotting, confocal microscopy, and real-time polymerase chain reaction; cell stress was assessed by measurement of oxidative stress and accumulation of ubiquitinated proteins and cell response by measurement of apoptosis and cell viability. Neuroblastoma cells were more sensitive to ER stress than melanoma and glioblastoma cells. GRP78 knockdown increased stress sensitivity of melanoma and glioblastoma cells, but not neuroblastoma cells. Over-expression of GRP78 decreased the stress sensitivity of melanoma and glioblastoma cells but, in contrast, increased the stress sensitivity of neuroblastoma cells by activation of caspase-3-independent cell death and substantially increased the expression of UPR activators, particularly inositol-requiring element 1 (IRE1). The results from this study suggest that cell-type specific differences in the relationships between GRP78 and the UPR activators, particularly IRE1, may determine differential sensitivity to ER stress.
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Affiliation(s)
- Shaun Martin
- Northern Institute for Cancer Research, Medical School, Newcastle University, NE2 4HH, United Kingdom
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20
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Liu Z, Dai S, Bones J, Ray S, Cha S, Karger BL, Li JJ, Wilson L, Hinckle G, Rossomando A. A quantitative proteomic analysis of cellular responses to high glucose media in Chinese hamster ovary cells. Biotechnol Prog 2015; 31:1026-38. [PMID: 25857574 DOI: 10.1002/btpr.2090] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 03/11/2015] [Indexed: 12/12/2022]
Abstract
A goal in recombinant protein production using Chinese hamster ovary (CHO) cells is to achieve both high specific productivity and high cell density. Addition of glucose to the culture media is necessary to maintain both cell growth and viability. We varied the glucose concentration in the media from 5 to 16 g/L and found that although specific productivity of CHO-DG44 cells increased with the glucose level, the integrated viable cell density decreased. To examine the biological basis of these results, we conducted a discovery proteomic study of CHO-DG44 cells grown under batch conditions in normal (5 g/L) or high (15 g/L) glucose over 3, 6, and 9 days. Approximately 5,000 proteins were confidently identified against an mRNA-based CHO-DG44 specific proteome database, with 2,800 proteins quantified with at least two peptides. A self-organizing map algorithm was used to deconvolute temporal expression profiles of quantitated proteins. Functional analysis of altered proteins suggested that differences in growth between the two glucose levels resulted from changes in crosstalk between glucose metabolism, recombinant protein expression, and cell death, providing an overall picture of the responses to high glucose environment. The high glucose environment may enhance recombinant dihydrofolate reductase in CHO cells by up-regulating NCK1 and down-regulating PRKRA, and may lower integrated viable cell density by activating mitochondrial- and endoplasmic reticulum-mediated cell death pathways by up-regulating HtrA2 and calpains. These proteins are suggested as potential targets for bioengineering to enhance recombinant protein production.
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Affiliation(s)
- Zhenke Liu
- Barnett Inst. and Dept. of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115
| | - Shujia Dai
- Barnett Inst. and Dept. of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115
| | - Jonathan Bones
- Barnett Inst. and Dept. of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115
| | - Somak Ray
- Barnett Inst. and Dept. of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115
| | - Sangwon Cha
- Barnett Inst. and Dept. of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115
| | - Barry L Karger
- Barnett Inst. and Dept. of Chemistry and Chemical Biology, Northeastern University, Boston, MA, 02115
| | - Jingyi Jessica Li
- Dept. of Statistics, University of California, Los Angeles, CA, 90095
| | - Lee Wilson
- Alnylam Pharmaceuticals, Cambridge, MA, 02142
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21
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Endoplasmic reticulum stress signaling in mammalian oocytes and embryos: life in balance. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 316:227-65. [PMID: 25805126 DOI: 10.1016/bs.ircmb.2015.01.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mammalian oocytes and embryos are exquisitely sensitive to a wide range of insults related to physical stress, chemical exposure, and exposures to adverse maternal nutrition or health status. Although cells manifest specific responses to various stressors, many of these stressors intersect at the endoplasmic reticulum (ER), where disruptions in protein folding and production of reactive oxygen species initiate downstream signaling events. These signals modulate mRNA translation and gene transcription, leading to recovery, activation of autophagy, or with severe and prolonged stress, apoptosis. ER stress signaling has recently come to the fore as a major contributor to embryo demise. Accordingly, agents that modulate or inhibit ER stress signaling have yielded beneficial effects on embryo survival and long-term developmental potential. We review here the mechanisms of ER stress signaling, their connections to mammalian oocytes and embryos, and the promising indications that interventions in this pathway may provide new opportunities for improving mammalian reproduction and health.
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22
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Li H, Dusseault J, Larose L. Nck1 depletion induces activation of the PI3K/Akt pathway by attenuating PTP1B protein expression. Cell Commun Signal 2014; 12:71. [PMID: 25398386 PMCID: PMC4236421 DOI: 10.1186/s12964-014-0071-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 10/19/2014] [Indexed: 12/17/2022] Open
Abstract
Background Activation of the PI3K/Akt pathway mediates crucial cellular functions regulated by receptor tyrosine kinases, such as cell growth, proliferation, survival and metabolism. Previously, we reported that the whole-body knockout of the Src homology domain-containing adaptor protein Nck1 improves overall glucose homeostasis and insulin-induced activation of the PI3K/Akt pathway in liver of obese mice. The aim of the current study is to elucidate the mechanism by which Nck1 depletion regulates hepatic insulin signaling. Results Here, we demonstrate that Nck1 regulates the activation of the PI3K/Akt pathway in a protein tyrosine phosphatase 1B (PTP1B)-dependent mechanism. Indeed, depletion of Nck1 by siRNA in HepG2 cells enhances PI3K-dependent basal and growth factor-induced Akt activation. In accordance, primary hepatocytes isolated from Nck1−/− mice also display enhanced Akt activation in response to insulin. Activation of the PI3K/Akt pathway in Nck1-depleted HepG2 cells relies on higher levels of tyrosine-phosphorylated proteins and correlates with decreased PTP1B levels. Interestingly, Nck1 and PTP1B in cells are found in a common molecular complex and their interaction is dependent on the SH3 domains of Nck1. Finally, Nck1 depletion in HepG2 cells neither affects PTP1B gene transcription nor PTP1B protein stability, suggesting that Nck1 modulates PTP1B expression at the translational level. Conclusion Our study provides strong evidence supporting that the adaptor protein Nck1 interacts with PTP1B and also regulates PTP1B expression. In this manner, Nck1 plays a role in regulating the PI3K/Akt pathway.
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Affiliation(s)
- Hui Li
- Department of Medicine, Polypeptide Laboratory, McGill University and The Research Institute of McGill University Health Centre, Montreal, QC, Canada.
| | - Julie Dusseault
- Department of Medicine, Polypeptide Laboratory, McGill University and The Research Institute of McGill University Health Centre, Montreal, QC, Canada.
| | - Louise Larose
- Department of Medicine, Polypeptide Laboratory, McGill University and The Research Institute of McGill University Health Centre, Montreal, QC, Canada.
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23
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Manié SN, Lebeau J, Chevet E. Cellular mechanisms of endoplasmic reticulum stress signaling in health and disease. 3. Orchestrating the unfolded protein response in oncogenesis: an update. Am J Physiol Cell Physiol 2014; 307:C901-7. [PMID: 25186011 DOI: 10.1152/ajpcell.00292.2014] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The endoplasmic reticulum (ER)-induced unfolded protein response (UPR) is an adaptive mechanism that is activated upon accumulation of misfolded proteins in the ER and aims at restoring ER homeostasis. In the past 10 years, the UPR has emerged as an important actor in the different phases of tumor growth. The UPR is transduced by three major ER resident stress sensors, which are protein kinase RNA-like ER kinase (PERK), activating transcription factor 6 (ATF6), and inositol-requiring enzyme-1 (IRE1). The signaling pathways elicited by those stress sensors have connections with metabolic pathways and with other plasma membrane receptor signaling networks. As such, the ER has an essential position as a signal integrator in the cell and is instrumental in the different phases of tumor progression. Herein, we describe and discuss the characteristics of an integrated signaling network that might condition the UPR biological outputs in a tissue- or stress-dependent manner. We discuss these issues in the context of the pathophysiological roles of UPR signaling in cancers.
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Affiliation(s)
- Serge N Manié
- University of Lyon, Lyon, France, and UMR CNRS 5286 - INSERM 1052 - University of Lyon, Cancer Research Center of Lyon, Team ER Stress and Tumorigenesis, Lyon, France;
| | - Justine Lebeau
- University of Lyon, Lyon, France, and UMR CNRS 5286 - INSERM 1052 - University of Lyon, Cancer Research Center of Lyon, Team ER Stress and Tumorigenesis, Lyon, France
| | - Eric Chevet
- Inserm U1053, Team Endoplasmic Reticulum Stress and Cancer, Université de Bordeaux, Bordeaux, France; and Centre Régional de Lutte Contre le Cancer Eugène Marquis, Rennes, France
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24
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Nezvitsky L, Tremblay ML, Takano T, Papillon J, Cybulsky AV. Complement-mediated glomerular injury is reduced by inhibition of protein-tyrosine phosphatase 1B. Am J Physiol Renal Physiol 2014; 307:F634-47. [DOI: 10.1152/ajprenal.00191.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The unfolded protein response and endoplasmic reticulum-associated degradation (ERAD) contribute to injury in renal glomerular diseases, including those mediated by complement C5b-9. In the present study, we address the role of protein-tyrosine phosphatase 1B (PTP1B) in complement-mediated glomerular injury and ERAD. In glomerular epithelial cells (GECs)/podocytes and PTP1B-deficient mouse embryonic fibroblasts exposed to complement, inhibition/deletion of PTP1B reduced ERAD, as monitored by the ERAD reporter CD3δ. Overexpression of PTP1B produced an effect similar to PTP1B deficiency on ERAD in complement-treated GECs. Complement-mediated cytotoxicity was reduced after PTP1B overexpression and tended to be reduced after PTP1B inhibition. PTP1B enhanced the induction of certain ERAD components via the inositol-requiring-1α branch of the unfolded protein response. PTP1B knockout mice with anti-glomerular basement membrane glomerulonephritis had decreased proteinuria and showed less podocyte loss and endoplasmic reticulum dysfunction compared with wild-type littermates. These results imply that endogenous levels of PTP1B are tightly regulated and that both overexpression and inhibition can affect ERAD. The cytoprotective effects of PTP1B deletion in cultured cells and in anti-glomerular basement membrane nephritis suggest that PTP1B may potentially be a therapeutic target in complement-mediated diseases.
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Affiliation(s)
- Lisa Nezvitsky
- Department of Medicine and Biochemistry, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
| | - Michel L. Tremblay
- Department of Medicine and Biochemistry, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
| | - Tomoko Takano
- Department of Medicine and Biochemistry, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
| | - Joan Papillon
- Department of Medicine and Biochemistry, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
| | - Andrey V. Cybulsky
- Department of Medicine and Biochemistry, McGill University Health Centre, McGill University, Montreal, Quebec, Canada
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25
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Yamani L, Latreille M, Larose L. Interaction of Nck1 and PERK phosphorylated at Y⁵⁶¹ negatively modulates PERK activity and PERK regulation of pancreatic β-cell proinsulin content. Mol Biol Cell 2013; 25:702-11. [PMID: 24371088 PMCID: PMC3937095 DOI: 10.1091/mbc.e13-09-0511] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
PERK is phosphorylated at Y561 in the juxtamembrane domain, and the adaptor protein Nck1, by directly interacting with phospho-Y561 PERK, negatively regulates PERK activity. Strong evidence is given supporting the biological relevance of Nck1 regulation of PERK function in modulating pancreatic β-cell proinsulin content. PERK, the PKR-like endoplasmic reticulum (ER) kinase, is an ER transmembrane serine/threonine protein kinase activated during ER stress. In this study, we provide evidence that the Src-homology domain–containing adaptor Nck1 negatively regulates PERK. We show that Nck directly binds to phosphorylated Y561 in the PERK juxtamembrane domain through its SH2 domain. We demonstrate that mutation of Y561 to a nonphosphorylatable residue (Y561F) promotes PERK activity, suggesting that PERK phosphorylation at Y561 (pY561PERK) negatively regulates PERK. In agreement, we show that pY561PERK delays PERK activation and signaling during ER stress. Compatible with a role for PERK in pancreatic β-cells, we provide strong evidence that Nck1 contributes to PERK regulation of pancreatic β-cell proteostasis. In fact, we demonstrated that down-regulation of Nck1 in mouse insulinoma MIN6 cells results in faster dephosphorylation of pY561PERK, which correlates with enhanced PERK activation, increased insulin biosynthesis, and PERK-dependent increase in proinsulin content. Furthermore, we report that pancreatic islets in whole-body Nck1-knockout mice contain more insulin than control littermates. Together our data strongly suggest that Nck1 negatively regulates PERK by interacting with PERK and protecting PERK from being dephosphorylated at its inhibitory site pY561 and in this way affects pancreatic β-cell proinsulin biogenesis.
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Affiliation(s)
- Lama Yamani
- Polypeptide Laboratory, Department of Medicine, and Health Centre Research Institute, McGill University, Montreal, QC H3A 2B2, Canada
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26
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FGF-2 prevents cancer cells from ER stress-mediated apoptosis via enhancing proteasome-mediated Nck degradation. Biochem J 2013; 452:139-45. [PMID: 23448571 DOI: 10.1042/bj20121671] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Induction of ER (endoplasmic reticulum) stress-mediated apoptosis in cancer cells represents an alternative approach for cancer therapy. Whether FGF-2 (fibroblast growth factor 2)-induced survival signals may interact with ER stress signalling in cancer cells remains elusive. In the present study, we showed that pretreatment with FGF-2 decreased the inhibition of DNA synthesis and induction of apoptosis by two different ER stress inducers, TM (tunicamycin) and TG (thapsigargin), in both human hepatoblastoma HepG2 cells and breast cancer MCF-7 cells. Pretreatment with FGF-2 prevented ER stress-mediated apoptosis by decreasing ER stress-induced CHOP [C/EBP (CCAAT/enhancer-binding protein)-homologous protein] expression. We further demonstrated that pretreatment with FGF-2 mediated the decrease in TM-induced CHOP expression and apoptosis through ERK1/2 (extracellular-signal-regulated kinases 1 and 2) pathway. Finally, we demonstrated that FGF-2 promoted proteasome-mediated degradation of Nck (non-catalytic region of tyrosine kinase adaptor protein), an SH (Src homology) 2/SH3-containing adaptor protein. Whereas overexpression of Nck1 decreased FGF-2-induced ERK1/2 phosphorylation to inhibit the effect of FGF-2 on TM-induced CHOP expression and apoptosis, a decrease in Nck expression prevented TM-induced CHOP expression and apoptosis. Taken together, the findings of the present study provide the first evidence that Nck plays a pivotal role in integrating FGF-2 and ER stress signals to counteract the ER stress deleterious effect on cancer cell survival.
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OSU-03012 sensitizes breast cancers to lapatinib-induced cell killing: a role for Nck1 but not Nck2. BMC Cancer 2013; 13:256. [PMID: 23706161 PMCID: PMC3674920 DOI: 10.1186/1471-2407-13-256] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/17/2013] [Indexed: 11/25/2022] Open
Abstract
Background Lapatinib is characterized as an ErbB1/ErbB2 dual inhibitor and has recently been approved for the treatment of metastatic breast cancer. In this study, we examined mechanisms associated with enhancing the activity of lapatinib via combination with other therapies. Methods In the present studies, estrogen receptor (ER) positive and ER negative breast cancer cells were genetically manipulated to up- or downregulate eIF2-alpha, its phospho-mutant, Nck1, or Nck2, then treated with OSU-03012, lapatinib or the combination and assayed for cytotoxicity/cytostaticity using clonogenic assays. Results Treatment of breast cancer cell lines with lapatinib and OSU-03012 (a small molecule derivative of the Cox-2 inhibitor celecoxib) induced synergistic cytotoxic/cytostatic effects. This combination therapy corresponded to an increase in the phosphorylation of eIF2-α at serine51 and a decrease in Nck1 expression. Ectopic expression of phospho-mutant eIF2-α (Ser51Ala) or downregulation of eIF2-α in addition to downregulation of the eIF2-α kinase PERK inhibited the synergistic and cytotoxic effects. Furthermore, ectopic expression of Nck1, but not Nck2 abolished the decrease in cell viability observed in combination-treated cells. Downregulation of Nck1 failed to “rescue” the ablation of the cytotoxic/cytostatic effects by the phospho-mutant of eIF2-α (Ser51Ala) demonstrating that Nck1 downregulation is upstream of eIF2-α phosphorylation in the anti-survival pathway activated by lapatinib and OSU-03012 treatment. Finally, co-immunoprecipitation assays indicated that eIF2-α dissociates from the Nck1/PP1 complex after OSU-03012 and lapatinib co-treatment. Conclusions These data indicate that OSU-03012 and lapatinib co-treatment is an effective combination therapy, which functions to enhance cell killing through the Nck1/eIF2 complex. Hence, this complex is a novel target for the treatment of metastatic breast cancer.
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Panzhinskiy E, Hua Y, Culver B, Ren J, Nair S. Endoplasmic reticulum stress upregulates protein tyrosine phosphatase 1B and impairs glucose uptake in cultured myotubes. Diabetologia 2013; 56. [PMID: 23178931 PMCID: PMC3568946 DOI: 10.1007/s00125-012-2782-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Endoplasmic reticulum (ER) stress has been recognised as a common pathway in the development of obesity-associated insulin resistance. Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signalling and is localised on the ER membrane. The aim of the study was to investigate the cross-talk between ER stress and PTP1B. METHODS Leptin-deficient obese (ob/ob), Ptp1b (also known as Ptpn1) knockout and C57BL/6J mice were subjected to a high-fat or normal-chow diet for 20 weeks. ER stress was induced in cultured myotubes by treatment with tunicamycin. Immunohistochemistry and western blotting were used to assess proteins involved in the ER stress response. Myotube glucose uptake was determined by measuring 2-deoxy[(3)H]glucose incorporation. RESULTS A high-fat diet induced ER stress and PTP1B expression in the muscle tissue of mice and these responses were attenuated by treatment with the ER chaperone tauroursodeoxycholic acid (TUDCA). Cultured myotubes exhibited increased levels of PTP1B in response to tunicamycin treatment. Silencing of Ptp1b with small interfering RNA (siRNA) or overexpression of Ptp1b with adenovirus construct failed to alter the levels of ER stress. Ptp1b knockout mice did not differ from the wild-type mice in the extent of tunicamycin-induced upregulation of glucose-regulated protein-78. However, tunicamycin-induced phosphorylation of eukaryotic initiation factor 2α and c-Jun NH(2)-terminal kinase-2 were significantly attenuated in the Ptp1b knockout mice. Treatment with TUDCA or silencing of PTP1B reversed tunicamycin-induced blunted myotube glucose uptake. CONCLUSIONS/INTERPRETATION Our data suggest that PTP1B is activated by ER stress and is required for full-range activation of ER stress pathways in mediating insulin resistance in the skeletal muscle.
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Affiliation(s)
- E. Panzhinskiy
- School of Pharmacy, University of Wyoming, College of Health Sciences, Laramie, WY 82071, USA. Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
| | - Y. Hua
- School of Pharmacy, University of Wyoming, College of Health Sciences, Laramie, WY 82071, USA. Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
| | - B. Culver
- School of Pharmacy, University of Wyoming, College of Health Sciences, Laramie, WY 82071, USA. Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
| | - J. Ren
- School of Pharmacy, University of Wyoming, College of Health Sciences, Laramie, WY 82071, USA. Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
| | - S. Nair
- School of Pharmacy, University of Wyoming, College of Health Sciences, Laramie, WY 82071, USA. Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, WY, USA
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Song JY, Bae HS, Koo DH, Lee JK, Jung HH, Lee KW, Lee NW. Candidates for tumor markers of cervical cancer discovered by proteomic analysis. J Korean Med Sci 2012; 27:1479-85. [PMID: 23255846 PMCID: PMC3524426 DOI: 10.3346/jkms.2012.27.12.1479] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 10/03/2012] [Indexed: 11/29/2022] Open
Abstract
Cervical cancer is the second most common gynecological cancer among Korean women. While nationwide screening program has developed, the pathogenesis of cervical cancer is unknown. The aim of this study was to compare the protein expression profiles between cervical squamous carcinomas and normal cervical tissues in order to identify proteins that are related to the cancer. Three cervical cancer tissue samples and three normal cervical tissue samples were obtained and protein expression was compared and was identified in the samples with the use of matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). A total of 20 proteins that showed up-regulated expression in the cervical cancer tissue samples were selected and identified. Seven proteins were matched to allograft inflammatory factor 1 (AIF-1), actine-like protein 2 (ALP2), brain type fatty acid-binding protein (B-FABP), NCK adaptor protein 1 (NCK-1), islet cell autoantigen 1 (ICA69), cationic trypsinogen (PRSS1), and cyclin-dependent kinase 4 (CDK4), but the remaining 13 proteins were unidentifiable. After confirmation by RT-PCR, Western blotting and immunohistochemistry, we found that B-FABP, NCK-1, and CDK4 were related to the pathogenesis of cervical cancer. These proteins are suggested as candidates of new pathological tumor markers for cervical cancer.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Blotting, Western
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/pathology
- Cyclin-Dependent Kinase 4/genetics
- Cyclin-Dependent Kinase 4/metabolism
- Electrophoresis, Gel, Two-Dimensional
- Fatty Acid-Binding Proteins/genetics
- Fatty Acid-Binding Proteins/metabolism
- Female
- Humans
- Immunohistochemistry
- Oncogene Proteins/genetics
- Oncogene Proteins/metabolism
- Proteomics
- Reverse Transcriptase Polymerase Chain Reaction
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Uterine Cervical Neoplasms/metabolism
- Uterine Cervical Neoplasms/pathology
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Affiliation(s)
- Jae Yun Song
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul, Korea
| | - Hyo Sook Bae
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul, Korea
| | - Do Hyoung Koo
- Department of Obstetrics and Gynecology, Graduate School of Medicine, Korea University, Seoul, Korea
| | - Jae Kwan Lee
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul, Korea
| | - Hak Hyun Jung
- Department of Otorhinolaryngology, Korea University College of Medicine, Seoul, Korea
| | - Kyu Wan Lee
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul, Korea
| | - Nak Woo Lee
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul, Korea
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Chakrabarti A, Chen AW, Varner JD. A review of the mammalian unfolded protein response. Biotechnol Bioeng 2011; 108:2777-93. [PMID: 21809331 PMCID: PMC3193940 DOI: 10.1002/bit.23282] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 06/21/2011] [Accepted: 07/15/2011] [Indexed: 12/14/2022]
Abstract
Proteins requiring post-translational modifications such as N-linked glycosylation are processed in the endoplasmic reticulum (ER). A diverse array of cellular stresses can lead to dysfunction of the ER and ultimately to an imbalance between protein-folding capacity and protein-folding load. Cells monitor protein folding by an inbuilt quality control system involving both the ER and the Golgi apparatus. Unfolded or misfolded proteins are tagged for degradation via ER-associated degradation (ERAD) or sent back through the folding cycle. Continued accumulation of incorrectly folded proteins can also trigger the unfolded protein response (UPR). In mammalian cells, UPR is a complex signaling program mediated by three ER transmembrane receptors: activating transcription factor 6 (ATF6), inositol requiring kinase 1 (IRE1) and double-stranded RNA-activated protein kinase (PKR)-like endoplasmic reticulum kinase (PERK). UPR performs three functions, adaptation, alarm, and apoptosis. During adaptation, the UPR tries to reestablish folding homeostasis by inducing the expression of chaperones that enhance protein folding. Simultaneously, global translation is attenuated to reduce the ER folding load while the degradation rate of unfolded proteins is increased. If these steps fail, the UPR induces a cellular alarm and mitochondrial mediated apoptosis program. UPR malfunctions have been associated with a wide range of disease states including tumor progression, diabetes, as well as immune and inflammatory disorders. This review describes recent advances in understanding the molecular structure of UPR in mammalian cells, its functional role in cellular stress, and its pathophysiology.
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Affiliation(s)
- Anirikh Chakrabarti
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca NY 14853
| | - Aaron W. Chen
- Polymer Science and Engineering, University of Massachusetts Amherst, Amherst MA 01003
| | - Jeffrey D. Varner
- Corresponding author: Jeffrey D. Varner, Assistant Professor, School of Chemical and Biomolecular Engineering, 244 Olin Hall, Cornell University, Ithaca NY, 14853, , Phone: (607) 255 -4258, Fax: (607) 255 -9166
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Abstract
Nck is an adaptor protein composed of three N-terminal Src Homology (SH) 3 domains followed by a unique C‑terminal SH2 domain. Like other SH2/SH3 domains-containing adaptor proteins, Nck mediates signal transduction from activated cell surface receptors by directing the flow of information to elicit properly orchestrated cell responses. In this way, Nck appears to be unique in its contribution to a wide variety of cellular processes. Moreover, in addition to the typical signal/pY-SH2/SH3-effectors mode of signaling, Nck also transduces signals through an inverse mode of -signaling (signal-SH3/SH2-pY/effectors) and from various cell compartments. Since Nck contributes to important morphogenic and mitogenic processes, deregulated expression of Nck could be detrimental to cellular homeostasis. In agreement, Nck expression has been found upregulated in numerous types of cancer. In this paper we delineate the main molecular -signaling -complexes associated with Nck, focusing on those involved in cancer progression.
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Affiliation(s)
- Mélissa Labelle-Côté
- Faculté de médecine, Université McGill, édifice Strathcona, Montréal, Québec, H3A 2B2 Canada.
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Latreille M, Laberge MK, Bourret G, Yamani L, Larose L. Deletion of Nck1 attenuates hepatic ER stress signaling and improves glucose tolerance and insulin signaling in liver of obese mice. Am J Physiol Endocrinol Metab 2011; 300:E423-34. [PMID: 20587749 DOI: 10.1152/ajpendo.00088.2010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Obesity has been shown to create stress in the endoplasmic reticulum (ER), and that initiates the activation of the unfolded protein response (UPR). This has been reported to cause insulin resistance in selective tissues through activation of the inositol-requiring enzyme 1α (IRE1α)-c-Jun NH(2)-terminal kinase (JNK) pathway, which results in the phosphorylation of the insulin receptor substrate-1 (IRS-1) at an inhibitory site and blocks insulin receptor signaling. In this study, we report that the Src homology domain-containing adaptor protein Nck1, previously shown to modulate the UPR, is of functional importance in obesity-induced ER stress signaling and inhibition of insulin actions. We have examined obese Nck1(-/-) and Nck1(+/+) mice for glucose tolerance, insulin sensitivity, and signaling as well as for ER stress markers and IRS-1 phosphorylation at Ser(307). Our findings show that obese Nck1-deficient mice display improved glucose disposal accompanied by enhanced insulin signaling in liver. This correlates with attenuated IRE1α and JNK activation and IRS-1 phosphorylation at Ser(307) compared with obese wild-type mice. Consistent with our in vivo data, we report that downregulation of Nck1 using siRNA in HepG2 cells results in decreased thapsigargin-induced IRE1α activation and signaling and IRS-1 phosphorylation at Ser(307), whereas it markedly enhances insulin signaling. Overall, in liver and in cultured cells, we show that depletion of Nck1 attenuates the UPR signal and its inhibitory action on insulin signaling. Taken all together, our findings implicate Nck1 in regulating the UPR, which secondary to obesity impairs glucose homeostasis and insulin actions.
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Affiliation(s)
- Mathieu Latreille
- Polypeptide Hormone Laboratory, Department of Experimental Medicine, Research Institute of the McGill University Health Centre, McGill University, 3640 University Street, Montreal, QC, Canada
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Lettau M, Pieper J, Janssen O. Nck adapter proteins: functional versatility in T cells. Cell Commun Signal 2009; 7:1. [PMID: 19187548 PMCID: PMC2661883 DOI: 10.1186/1478-811x-7-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Accepted: 02/02/2009] [Indexed: 01/16/2023] Open
Abstract
Nck is a ubiquitously expressed adapter protein that is almost exclusively built of one SH2 domain and three SH3 domains. The two isoproteins of Nck are functionally redundant in many aspects and differ in only few amino acids that are mostly located in the linker regions between the interaction modules. Nck proteins connect receptor and non-receptor tyrosine kinases to the machinery of actin reorganisation. Thereby, Nck regulates activation-dependent processes during cell polarisation and migration and plays a crucial role in the signal transduction of a variety of receptors including for instance PDGF-, HGF-, VEGF- and Ephrin receptors. In most cases, the SH2 domain mediates binding to the phosphorylated receptor or associated phosphoproteins, while SH3 domain interactions lead to the formation of larger protein complexes. In T lymphocytes, Nck plays a pivotal role in the T cell receptor (TCR)-induced reorganisation of the actin cytoskeleton and the formation of the immunological synapse. However, in this context, two different mechanisms and adapter complexes are discussed. In the first scenario, dependent on an activation-induced conformational change in the CD3epsilon subunits, a direct binding of Nck to components of the TCR/CD3 complex was shown. In the second scenario, Nck is recruited to the TCR complex via phosphorylated Slp76, another central constituent of the membrane proximal activation complex. Over the past years, a large number of putative Nck interactors have been identified in different cellular systems that point to diverse additional functions of the adapter protein, e.g. in the control of gene expression and proliferation.
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Affiliation(s)
- Marcus Lettau
- University Hospital Schleswig-Holstein Campus Kiel, Institute of Immunology, Molecular Immunology, Arnold-Heller-Str 3, Bldg 17, D-24105 Kiel, Germany.
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Cardin E, Larose L. Nck-1 interacts with PKR and modulates its activation by dsRNA. Biochem Biophys Res Commun 2008; 377:231-5. [PMID: 18835251 DOI: 10.1016/j.bbrc.2008.09.112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 09/23/2008] [Indexed: 11/19/2022]
Abstract
Activation of the double-stranded RNA (dsRNA)-activated protein kinase PKR results in inhibition of general translation through phosphorylation of the eukaryotic initiation factor 2 alpha-subunit on serine 51 (eIF2alphaSer51). Previously, we have reported that the adaptor protein Nck-1 modulates eIF2alphaSer51 phosphorylation by a subset of eIF2alpha kinases, including PKR. Herein, we demonstrate that Nck-1 prevents efficient activation of PKR by dsRNA, revealing that Nck-1 acts at the level of PKR. In agreement, Nck-1 impairs p38MAPK activation and attenuates cell death induced by dsRNA, in addition to diminish eIF2alphaSer51 phosphorylation. Our data show that the inhibitory effect of Nck-1 on PKR is reversible, as it could be overcome by increasing levels of dsRNA. Interestingly, we found that Nck-1 interacts with the inactive form of PKR, independently of its Src homology domains. Furthermore, we uncovered that Nck-1 is substrate of PKR in vitro. All together, our data provide the first evidence identifying Nck-1 as a novel endogenous regulator of PKR and support the notion that Nck-1-PKR interaction could be a way to limit PKR activation.
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Affiliation(s)
- Eric Cardin
- Experimental Medicine Department, Polypeptide Laboratory, McGill University, Montreal, Que, Canada
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Yang LP, Wu LM, Guo XJ, Li Y, Tso MOM. Endoplasmic reticulum stress is activated in light-induced retinal degeneration. J Neurosci Res 2008; 86:910-9. [PMID: 17929311 DOI: 10.1002/jnr.21535] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Exposure to excessive levels of light induces photoreceptor apoptosis and has previously been used as a model for the study of retinal degeneration. During the light exposure, intracellular calcium levels increase, and reactive oxygen species (ROS) are generated, which have been shown to cause endoplasmic reticulum (ER) stress. In the present study, we investigated the role of ER stress in light-induced photoreceptor apoptosis. Our study demonstrated that, after light exposure, the ER stress sensors including glucose-regulated protein-78 (GRP78/BiP), caspase-12, phospho-eukaryotic initiation factor 2 alpha (eIF2 alpha), and phospho-pancreatic ER kinase (PERK) were significantly up-regulated in a time-dependent manner. The up-regulation of these proteins coincided with or preceded the photoreceptor apoptosis indicated by TUNEL. These data showed that ER stress played an important role in light-induced photoreceptor apoptosis. Therefore, ER stress modulators could be strong candidates as therapeutic agents in the treatment of retinal degenerative diseases.
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Affiliation(s)
- Li-ping Yang
- Peking University Eye Center, Peking University Third Hospital, Peking University, Beijing, People's Republic of China.
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Abstract
The endoplasmic reticulum (ER) is the first sub-cellular compartment encountered by secretory proteins en route to the plasma membrane. Newly synthesized secretory proteins translocate into the ER lumen and acquire their correct conformation prior to being exported to later compartments. When folding is not properly achieved, proteins accumulate in the ER due to resident quality control machineries and terminally misfolded proteins are ultimately degraded through the ER-associated degradation pathway. All these molecular machines function in a coordinated fashion to restore and maintain ER homeostasis. A fifth molecular machine plays a coordinating role in the ER. Indeed, the ER stress signaling machinery signals ER dysfunction to the rest of the cell and consequently integrates the functions of the four other molecular machines to improve their operation in stressful conditions. In this work, we have attempted to define the ER as a molecular biological system regulated by its own specific signaling pathways defined as the Unfolded Protein Response to delineate a systems biology approach of ER stress signaling.
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Moenner M, Pluquet O, Bouchecareilh M, Chevet E. Integrated endoplasmic reticulum stress responses in cancer. Cancer Res 2007; 67:10631-4. [PMID: 18006802 DOI: 10.1158/0008-5472.can-07-1705] [Citation(s) in RCA: 324] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER) has emerged as a major site of cellular homeostasis regulation, particularly in the unfolded protein response, which is being found to play a major role in cancer and many other diseases. Here, we address ER-mediated signaling and regulations in the context of environmental challenges in cancer, such as hypoxia, angiogenesis, and chemotherapeutic resistance, and we discuss how ER-resident molecular machines become deregulated and involved in cancer-related pathology. Further exploration of how the ER senses, signals, and adapts to stress may redefine and deepen our understanding of its functions in cancer pathobiology.
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Affiliation(s)
- Michel Moenner
- Institut National de la Sante et de la Recherche Medicale, E0113, Bordeaux, France
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Boyle EC, Brown NF, Brumell JH, Finlay BB. Src homology domain 2 adaptors affect adherence of Salmonella enterica serovar Typhimurium to non-phagocytic cells. MICROBIOLOGY-SGM 2007; 153:3517-3526. [PMID: 17906149 DOI: 10.1099/mic.0.2007/008581-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The ability of Salmonella enterica serovar Typhimurium (S. Typhimurium) to penetrate the intestinal epithelium is key to its pathogenesis. Bacterial invasion can be seen as a two-step process initially requiring adherence to the host cell surface followed by internalization into the host cell. Evidence suggests that adherence of S. Typhimurium to host cells is receptor-mediated; however, the host cell receptor(s) has/have not been identified. Internalization of S. Typhimurium absolutely requires the actin cytoskeleton yet only a few of the cytoskeletal components involved in this process have been identified. In order to identify host proteins that may play a role in S. Typhimurium invasion, the recruitment of actin-associated proteins was investigated. The contribution of recruited Src homology 2 adaptor proteins to invasion was further investigated and it was found that, while not involved in bacterial internalization itself, the adaptors Nck and ShcA influenced adherence of S. Typhimurium to non-phagocytic cells.
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Affiliation(s)
- Erin C Boyle
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Nat F Brown
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - John H Brumell
- Department of Molecular and Medical Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - B Brett Finlay
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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Cardin E, Latreille M, Khoury C, Greenwood MT, Larose L. Nck-1 selectively modulates eIF2alphaSer51 phosphorylation by a subset of eIF2alpha-kinases. FEBS J 2007; 274:5865-75. [PMID: 17944934 DOI: 10.1111/j.1742-4658.2007.06110.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phosphorylation of the alpha-subunit of the eukaryotic initiation factor 2 (eIF2) on Ser51 is an early event associated with the down-regulation of protein synthesis at the level of translation and initiation of a transcriptional program. This constitutes a potent mechanism to overcome various stress conditions. In mammals, four eIF2alpha-kinases [PKR-like endoplasmic reticulum kinase (PERK), dsRNA-activated protein kinase (PKR), heme regulated inhibitor (HRI) and general control nonderepressible-2 (GCN2)], activated following specific stresses, have been shown to be involved in this process. In this article, we report that the ubiquitously expressed adaptor protein Nck, composed only of Src homology domains and classically implicated in cell signaling by activated plasma membrane receptor tyrosine kinases, modulates eIF2alpha-kinase-mediated eIF2alphaSer51 phosphorylation in a specific manner. Our results show that Nck not only prevents eIF2alpha phosphorylation upon PERK activation, as reported previously, but also reduces eIF2alpha phosphorylation in conditions leading to PKR and HRI activation. By contrast, the overexpression of Nck in mammalian cells fails to attenuate eIF2alphaSer51 phosphorylation in response to amino acid starvation, a stress well known to activate GCN2. This observation is further confirmed by showing that Nck fails to alter eIF2alphaSer51 phosphorylation in Saccharomyces cerevisiae, for which the sole eIF2alpha-kinase is Gcn2p. Our results suggest the existence of a novel mechanism that specifically modulates the phosphorylation of eIF2alpha on Ser51 under various stress conditions.
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Affiliation(s)
- Eric Cardin
- Polypeptide Laboratory, Department of Experimental Medicine, McGill University, Montreal, Canada
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Schröder M. The unfolded protein response. Mol Biotechnol 2007; 34:279-90. [PMID: 17172673 DOI: 10.1385/mb:34:2:279] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/11/2022]
Abstract
The unfolded protein response (UPR) is a signal transduction network activated by inhibition of protein folding in the endoplasmic reticulum (ER). The UPR coordinates adaptive responses to this stress situation, including induction of ER resident molecular chaperone and protein foldase expression to increase the protein folding capacity of the ER, induction of phospholipid synthesis, attenuation of general translation, and upregulation of ER-associated degradation to decrease the unfolded protein load of the ER, and an antioxidant response. Upon severe or prolonged ER stress the UPR induces apoptosis to eliminate unhealthy cells from an organism or a population. In this review, I will summarize our current knowledge about signal transduction pathways involved in transducing the unfolded protein signal from the ER to the nucleus or the cytosol.
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Affiliation(s)
- Martin Schröder
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom.
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Latreille M, Larose L. Nck in a Complex Containing the Catalytic Subunit of Protein Phosphatase 1 Regulates Eukaryotic Initiation Factor 2α Signaling and Cell Survival to Endoplasmic Reticulum Stress. J Biol Chem 2006; 281:26633-44. [PMID: 16835242 DOI: 10.1074/jbc.m513556200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Stress imposed on the endoplasmic reticulum (ER) induces the phosphorylation of the alpha-subunit of the eukaryotic initiation factor 2 (eIF2) on Ser51. This results in transient inhibition of general translation initiation while concomitantly activating a signaling pathway that promotes the expression of genes whose products improve ER function. Conversely, dephosphorylation of eIF2alphaSer51 is accomplished by protein phosphatase 1 (PP1c) complexes containing either the protein CReP or GADD34, which target PP1c to eIF2. Here, we demonstrate that the Src homology (SH) domain-containing adaptor Nck is a key component of a molecular complex that controls eIF2alpha phosphorylation and signaling in response to ER stress. We show that overexpression of Nck decreases basal and ER stress-induced eIF2alpha phosphorylation and the attendant induction of ATF4 and CHOP. In contrast, we demonstrate that the mouse embryonic fibroblasts lacking both isoforms of Nck (Nck1-/-Nck2-/-) show higher levels of eIF2alpha phosphorylation and premature induction of ATF4, CHOP, and GADD34 in response to ER stress and finally, are more resistant to cell death induced by prolonged ER stress conditions. We establish that a significant amount of Nck protein localizes at the ER and is in a complex with eIF2 subunits. Further analysis of this complex revealed that it also contains the Ser/Thr phosphatase PP1c, its regulatory subunit CReP, and dephosphorylates eIF2alpha on Ser51 in vitro. Overall, we demonstrate that Nck as a component of the CReP/PP1c holophosphatase complex contributes to maintain eIF2alpha in a hypophosphorylated state. In this manner, Nck modulates translation and eIF2alpha signaling in response to ER stress.
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Affiliation(s)
- Mathieu Latreille
- Polypeptide Hormone Laboratory, Department of Medicine, McGill University, Montreal, Quebec H3A 2B2, Canada
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43
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Boyce M, Yuan J. Cellular response to endoplasmic reticulum stress: a matter of life or death. Cell Death Differ 2006; 13:363-73. [PMID: 16397583 DOI: 10.1038/sj.cdd.4401817] [Citation(s) in RCA: 539] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The proper functioning of the endoplasmic reticulum (ER) is critical for numerous aspects of cell physiology. Accordingly, all eukaryotes react rapidly to ER dysfunction through a set of adaptive pathways known collectively as the ER stress response (ESR). Normally, this suite of responses succeeds in restoring ER homeostasis. However, in metazoans, persistent or intense ER stress can also trigger programmed cell death, or apoptosis. ER stress and the apoptotic program coupled to it have been implicated in many important pathologies but the regulation and execution of ER stress-induced apoptosis in mammals remain incompletely understood. Here, we review what is known about the ESR in both yeast and mammals, and highlight recent findings on the mechanism and pathophysiological importance of ER stress-induced apoptosis.
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Affiliation(s)
- M Boyce
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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44
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Llorens F, Duarri A, Sarró E, Roher N, Plana M, Itarte E. The N-terminal domain of the human eIF2beta subunit and the CK2 phosphorylation sites are required for its function. Biochem J 2006; 394:227-36. [PMID: 16225457 PMCID: PMC1386020 DOI: 10.1042/bj20050605] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
CK2 (protein kinase CK2) is known to phosphorylate eIF2 (eukaryotic translation initiation factor 2) in vitro; however, its implication in this process in living cells has remained to be confirmed. The combined use of chemical inhibitors (emodin and apigenin) of CK2 together with transfection experiments with the wild-type of the K68A kinase-dead mutant form of CK2alpha evidenced the direct involvement of this protein kinase in eIF2beta phosphorylation in cultured HeLa cells. Transfection of HeLa cells with human wild-type eIF2beta or its phosphorylation site mutants showed Ser2 as the main site for constitutive eIF2beta phosphorylation, whereas phosphorylation at Ser67 seems more restricted. In vitro phosphorylation of eIF2beta also pointed to Ser2 as a preferred site for CK2 phosphorylation. Overexpression of the eIF2beta S2/67A mutant slowed down the rate of protein synthesis stimulated by serum, although less markedly than the overexpression of the Delta2-138 N-terminal-truncated form of eIF2beta (eIF2beta-CT). Mutation at Ser2 and Ser67 did not affect eIF2beta integrating into the eIF2 trimer or being able to complex with eIF5 and CK2alpha. The eIF2beta-CT form was also incorporated into the eIF2 trimer but did not bind to eIF5. Overexpression of eIF2beta slightly decreased HeLa cell viability, an effect that was more evident when overexpressing the eIF2beta S2/67A mutant. Cell death was particularly marked when overexpressing the eIF2beta-CT form, being detectable at doses where eIF2beta and eIF2beta S2/67A were ineffective. These results suggest that Ser2 and Ser67 contribute to the important role of the N-terminal region of eIF2beta for its function in mammals.
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Affiliation(s)
- Franc Llorens
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Ciències, Universitat Autònoma de Barcelona, Edifici Cs, Campus de Bellaterra, 08193 Bellaterra, Barcelona, Spain.
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45
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Verma R, Kovari I, Soofi A, Nihalani D, Patrie K, Holzman LB. Nephrin ectodomain engagement results in Src kinase activation, nephrin phosphorylation, Nck recruitment, and actin polymerization. J Clin Invest 2006; 116:1346-59. [PMID: 16543952 PMCID: PMC1401486 DOI: 10.1172/jci27414] [Citation(s) in RCA: 256] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Accepted: 02/07/2006] [Indexed: 12/21/2022] Open
Abstract
A properly established and maintained podocyte intercellular junction, or slit diaphragm, is a necessary component of the selective permeability barrier of the kidney glomerulus. The observation that mutation or deletion of the slit diaphragm transmembrane protein nephrin results in failure of podocyte foot process morphogenesis and concomitant proteinuria first suggested the hypothesis that nephrin serves as a component of a signaling complex that directly integrates podocyte junctional integrity with cytoskeletal dynamics. The observations made herein provide the first direct evidence to our knowledge for a phosphorylation-mediated signaling mechanism by which this integrative function is derived. Our data support the model that during podocyte intercellular junction formation, engagement of the nephrin ectodomain induces transient Fyn catalytic activity that results in nephrin phosphorylation on specific nephrin cytoplasmic domain tyrosine residues. We found that this nephrin phosphorylation event resulted in recruitment of the SH2-SH3 domain-containing adapter protein Nck and assembly of actin filaments in an Nck-dependent fashion. Considered in the context of the role of nephrin family proteins in other organisms and the integral relationship of actin dynamics and junction formation, these observations establish a function for nephrin in regulating actin cytoskeletal dynamics.
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Affiliation(s)
- Rakesh Verma
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Department of Veterans Affairs, Ann Arbor, Michigan, USA
| | - Iulia Kovari
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Department of Veterans Affairs, Ann Arbor, Michigan, USA
| | - Abdul Soofi
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Department of Veterans Affairs, Ann Arbor, Michigan, USA
| | - Deepak Nihalani
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Department of Veterans Affairs, Ann Arbor, Michigan, USA
| | - Kevin Patrie
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Department of Veterans Affairs, Ann Arbor, Michigan, USA
| | - Lawrence B. Holzman
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Department of Veterans Affairs, Ann Arbor, Michigan, USA
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Hao W, Takano T, Guillemette J, Papillon J, Ren G, Cybulsky AV. Induction of Apoptosis by the Ste20-like Kinase SLK, a Germinal Center Kinase That Activates Apoptosis Signal-regulating Kinase and p38. J Biol Chem 2006; 281:3075-84. [PMID: 16316999 DOI: 10.1074/jbc.m511744200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression and activity of the germinal center kinase, Ste20-like kinase (SLK), are increased during kidney development and recovery from ischemic acute renal failure. In this study, we characterize the activation and functional role of SLK. SLK underwent dimerization via the C-terminal domain, and dimerization enhanced SLK activity. In contrast, the C-terminal domain of SLK did not dimerize with a related kinase, Mst1, and did not affect Mst1 activity. Phosphorylation/dephosphorylation of SLK were not associated with changes in kinase activity. SLK induced phosphorylation of apoptosis signal-regulating kinase-1 (ASK1) and increased ASK1 activity, indicating that ASK1 is a substrate of SLK. Moreover, SLK stimulated phosphorylation of p38 mitogen-activated protein kinase via ASK1, but not c-Jun N-terminal kinase nor extracellular signal-regulated kinase. Chemical anoxia and recovery during re-exposure to glucose (ischemia-reperfusion injury in cell culture) stimulated SLK activity. Overexpression of SLK enhanced anoxia/recovery-induced apoptosis, release of cytochrome c, and activities of caspase-8 and -9, and apoptosis was reduced significantly with p38 and caspase-9 inhibitors. Induction of the endoplasmic reticulum stress response by anoxia/recovery or tunicamycin (monitored by induction of Bip or Grp94 expression, phosphorylation of eukaryotic translation initiation factor 2alpha subunit, expression of CHOP, and activation of caspase-12) was attenuated in cells that overexpress SLK. Thus, SLK is an anoxia/recovery-dependent kinase that is activated via homodimerization and that signals via ASK1 and p38 to promote apoptosis. Attenuation of the protective aspects of the endoplasmic reticulum stress response by SLK may contribute to its proapoptotic effect.
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Affiliation(s)
- Wen Hao
- Department of Medicine, McGill University Health Centre, Montreal, Quebec H3A 1A1, Canada
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47
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Su Q, Wang S, Baltzis D, Qu LK, Wong AHT, Koromilas AE. Tyrosine phosphorylation acts as a molecular switch to full-scale activation of the eIF2alpha RNA-dependent protein kinase. Proc Natl Acad Sci U S A 2005; 103:63-8. [PMID: 16373505 PMCID: PMC1324992 DOI: 10.1073/pnas.0508207103] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Phosphorylation of the alpha-subunit of translation eukaryotic initiation factor-2 (eIF2) leads to the inhibition of protein synthesis in response to diverse conditions of stress. Serine/threonine RNA-dependent protein kinase (PKR) is an eIF2alpha kinase family member induced by type I IFN and activated in response to dsRNA or virus infection. Herein, we demonstrate that human PKR is a dual specificity kinase phosphorylated at Y101, Y162 and Y293 in vitro and in vivo. Site-specific tyrosine phosphorylation is essential for efficient dsRNA-binding, dimerization, kinase activation and eIF2alpha phosphorylation of PKR. Biologically, tyrosine phosphorylation of PKR mediates the antiviral and antiproliferative properties of the kinase through its ability to control translation. Our data demonstrate an important role of tyrosine phosphorylation in biochemical and biological processes caused or mediated by the activation of the eIF2alpha kinase PKR.
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Affiliation(s)
- Qiaozhu Su
- Lady Davis Institute for Medical Research, McGiIl University, Sir Mortimer B. Davis Jewish General Hospital, Montreal, QC, Canada H3T 1E2
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48
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Abstract
In the endoplasmic reticulum (ER), secretory and transmembrane proteins fold into their native conformation and undergo posttranslational modifications important for their activity and structure. When protein folding in the ER is inhibited, signal transduction pathways, which increase the biosynthetic capacity and decrease the biosynthetic burden of the ER to maintain the homeostasis of this organelle, are activated. These pathways are called the unfolded protein response (UPR). In this review, we briefly summarize principles of protein folding and molecular chaperone function important for a mechanistic understanding of UPR-signaling events. We then discuss mechanisms of signal transduction employed by the UPR in mammals and our current understanding of the remodeling of cellular processes by the UPR. Finally, we summarize data that demonstrate that UPR signaling feeds into decision making in other processes previously thought to be unrelated to ER function, e.g., eukaryotic starvation responses and differentiation programs.
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Affiliation(s)
- Martin Schröder
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, United Kingdom.
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49
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Schröder M, Kaufman RJ. ER stress and the unfolded protein response. Mutat Res 2005; 569:29-63. [PMID: 15603751 DOI: 10.1016/j.mrfmmm.2004.06.056] [Citation(s) in RCA: 1294] [Impact Index Per Article: 68.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2004] [Accepted: 06/10/2004] [Indexed: 02/08/2023]
Abstract
Conformational diseases are caused by mutations altering the folding pathway or final conformation of a protein. Many conformational diseases are caused by mutations in secretory proteins and reach from metabolic diseases, e.g. diabetes, to developmental and neurological diseases, e.g. Alzheimer's disease. Expression of mutant proteins disrupts protein folding in the endoplasmic reticulum (ER), causes ER stress, and activates a signaling network called the unfolded protein response (UPR). The UPR increases the biosynthetic capacity of the secretory pathway through upregulation of ER chaperone and foldase expression. In addition, the UPR decreases the biosynthetic burden of the secretory pathway by downregulating expression of genes encoding secreted proteins. Here we review our current understanding of how an unfolded protein signal is generated, sensed, transmitted across the ER membrane, and how downstream events in this stress response are regulated. We propose a model in which the activity of UPR signaling pathways reflects the biosynthetic activity of the ER. We summarize data that shows that this information is integrated into control of cellular events, which were previously not considered to be under control of ER signaling pathways, e.g. execution of differentiation and starvation programs.
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Affiliation(s)
- Martin Schröder
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK
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50
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Nguyên DT, Kebache S, Fazel A, Wong HN, Jenna S, Emadali A, Lee EH, Bergeron JJM, Kaufman RJ, Larose L, Chevet E. Nck-dependent activation of extracellular signal-regulated kinase-1 and regulation of cell survival during endoplasmic reticulum stress. Mol Biol Cell 2004; 15:4248-60. [PMID: 15201339 PMCID: PMC515356 DOI: 10.1091/mbc.e03-11-0851] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 05/21/2004] [Accepted: 06/07/2004] [Indexed: 11/11/2022] Open
Abstract
In response to stress, the endoplasmic reticulum (ER) signaling machinery triggers the inhibition of protein synthesis and up-regulation of genes whose products are involved in protein folding, cell cycle exit, and/or apoptosis. We demonstrate that the misfolding agents azetidine-2-carboxylic acid (Azc) and tunicamycin initiate signaling from the ER, resulting in the activation of Jun-N-terminal kinase, p44(MAPK)/extracellular signal-regulated kinase-1 (ERK-1), and p38(MAPK) through IRE1alpha-dependent mechanisms. To characterize the ER proximal signaling events involved, immuno-isolated ER membranes from rat fibroblasts treated with ER stress inducers were used to reconstitute the activation of the stress-activated protein kinase/mitogen-activate protein kinase (MAPK) pathways in vitro. This allowed us to demonstrate a role for the SH2/SH3 domain containing adaptor Nck in ERK-1 activation after Azc treatment. We also show both in vitro and in vivo that under basal conditions ER-associated Nck represses ERK-1 activation and that upon ER stress this pool of Nck dissociates from the ER membrane to allow ERK-1 activation. Moreover, under the same conditions, Nck-null cells elicit a stronger ERK-1 activation in response to Azc stress, thus, correlating with an enhanced survival phenotype. These data delineate a novel mechanism for the regulation of ER stress signaling to the MAPK pathway and demonstrate a critical role for Nck in ER stress and cell survival.
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Affiliation(s)
- Duc Thang Nguyên
- Department of Surgery, McGill University, Montreal, Quebec, H3A 1A1 Canada
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