1
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Pontisso I, Ornelas-Guevara R, Chevet E, Combettes L, Dupont G. Gradual ER calcium depletion induces a progressive and reversible UPR signaling. PNAS NEXUS 2024; 3:pgae229. [PMID: 38933930 PMCID: PMC11200134 DOI: 10.1093/pnasnexus/pgae229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 05/29/2024] [Indexed: 06/28/2024]
Abstract
The unfolded protein response (UPR) is a widespread signal transduction pathway triggered by endoplasmic reticulum (ER) stress. Because calcium (Ca2+) is a key factor in the maintenance of ER homeostasis, massive Ca2+ depletion of the ER is a potent inducer of ER stress. Although moderate changes in ER Ca2+ drive the ubiquitous Ca2+ signaling pathways, a possible incremental relationship between UPR activation and Ca2+ changes has yet to be described. Here, we determine the sensitivity and time-dependency of activation of the three ER stress sensors, inositol-requiring protein 1 alpha (IRE1α), protein kinase R-like ER kinase (PERK), and activating transcription factor 6 alpha (ATF6α) in response to controlled changes in the concentration of ER Ca2+ in human cultured cells. Combining Ca2+ imaging, fluorescence recovery after photobleaching experiments, biochemical analyses, and mathematical modeling, we uncover a nonlinear rate of activation of the IRE1α branch of UPR, as compared to the PERK and ATF6α branches that become activated gradually with time and are sensitive to more important ER Ca2+ depletions. However, the three arms are all activated within a 1 h timescale. The model predicted the deactivation of PERK and IRE1α upon refilling the ER with Ca2+. Accordingly, we showed that ER Ca2+ replenishment leads to the complete reversion of IRE1α and PERK phosphorylation in less than 15 min, thus revealing the highly plastic character of the activation of the upstream UPR sensors. In conclusion, our results reveal a dynamic and dose-sensitive Ca2+-dependent activation/deactivation cycle of UPR induction, which could tightly control cell fate upon acute and/or chronic stress.
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Affiliation(s)
- Ilaria Pontisso
- U1282 “Calcium Signaling and Microbial Infections”, Institut de Biologie Intégrative de la Cellule (I2BC)—Université Paris-Saclay, Gif-Sur-Yvette 91190, France
| | - Roberto Ornelas-Guevara
- Unit of Theoretical Chronobiology, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Eric Chevet
- Inserm U1242 Université de Rennes, 35000 Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis, 35042 Rennes, France
| | - Laurent Combettes
- U1282 “Calcium Signaling and Microbial Infections”, Institut de Biologie Intégrative de la Cellule (I2BC)—Université Paris-Saclay, Gif-Sur-Yvette 91190, France
| | - Geneviève Dupont
- Unit of Theoretical Chronobiology, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
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2
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Le Goupil S, Laprade H, Aubry M, Chevet E. Exploring the IRE1 interactome: From canonical signaling functions to unexpected roles. J Biol Chem 2024; 300:107169. [PMID: 38494075 PMCID: PMC11007444 DOI: 10.1016/j.jbc.2024.107169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/04/2024] [Accepted: 03/08/2024] [Indexed: 03/19/2024] Open
Abstract
The unfolded protein response is a mechanism aiming at restoring endoplasmic reticulum (ER) homeostasis and is likely involved in other adaptive pathways. The unfolded protein response is transduced by three proteins acting as sensors and triggering downstream signaling pathways. Among them, inositol-requiring enzyme 1 alpha (IRE1α) (referred to as IRE1 hereafter), an endoplasmic reticulum-resident type I transmembrane protein, exerts its function through both kinase and endoribonuclease activities, resulting in both X-box binding protein 1 mRNA splicing and RNA degradation (regulated ire1 dependent decay). An increasing number of studies have reported protein-protein interactions as regulators of these signaling mechanisms, and additionally, driving other noncanonical functions. In this review, we deliver evolutive and structural insights on IRE1 and further describe how this protein interaction network (interactome) regulates IRE1 signaling abilities or mediates other cellular processes through catalytic-independent mechanisms. Moreover, we focus on newly discovered targets of IRE1 kinase activity and discuss potentially novel IRE1 functions based on the nature of the interactome, thereby identifying new fields to explore regarding this protein's biological roles.
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Affiliation(s)
- Simon Le Goupil
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France.
| | - Hadrien Laprade
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France
| | - Marc Aubry
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France
| | - Eric Chevet
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France
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3
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Wirojsirasak W, Songsri P, Jongrungklang N, Tangphatsornruang S, Klomsa-ard P, Ukoskit K. A Large-Scale Candidate-Gene Association Mapping for Drought Tolerance and Agronomic Traits in Sugarcane. Int J Mol Sci 2023; 24:12801. [PMID: 37628982 PMCID: PMC10454574 DOI: 10.3390/ijms241612801] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 08/09/2023] [Accepted: 08/12/2023] [Indexed: 08/27/2023] Open
Abstract
Dissection of the genetic loci controlling drought tolerance traits with a complex genetic inheritance is important for drought-tolerant sugarcane improvement. In this study, we conducted a large-scale candidate gene association study of 649 candidate genes in a sugarcane diversity panel to identify genetic variants underlying agronomic traits and drought tolerance indices evaluated in plant cane and ratoon cane under water-stressed (WS) and non-stressed (NS) environments. We identified 197 significant marker-trait associations (MTAs) in 141 candidate genes associated with 18 evaluated traits with the Bonferroni correction threshold (α = 0.05). Out of the total, 95 MTAs in 78 candidate genes and 62 MTAs in 58 candidate genes were detected under NS and WS conditions, respectively. Most MTAs were found only in specific water regimes and crop seasons. These MTAs explained 7.93-30.52% of phenotypic variation. Association mapping results revealed that 34, 59, and 104 MTAs involved physiological and molecular adaptation, phytohormone metabolism, and drought-inducible genes. They identified 19 pleiotropic genes associated with more than one trait and many genes related to drought tolerance indices. The genetic and genomic resources identified in this study will enable the combining of yield-related traits and sugar-related traits with agronomic value to optimize the yield of sugarcane cultivars grown under drought-stressed and non-stressed environments.
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Affiliation(s)
- Warodom Wirojsirasak
- Department of Biotechnology, Faculty of Science and Technology, Rangsit Campus, Thammasat University, Pathum Thani 12120, Thailand;
- Mitr Phol Innovation and Research Center, Chaiyaphum 36110, Thailand;
| | - Patcharin Songsri
- Department of Agronomy, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand; (P.S.); (N.J.)
- Northeast Thailand Cane and Sugar Research Center, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Nakorn Jongrungklang
- Department of Agronomy, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand; (P.S.); (N.J.)
- Northeast Thailand Cane and Sugar Research Center, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Sithichoke Tangphatsornruang
- National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani 12120, Thailand;
| | | | - Kittipat Ukoskit
- Department of Biotechnology, Faculty of Science and Technology, Rangsit Campus, Thammasat University, Pathum Thani 12120, Thailand;
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4
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Lin Y, Feng Y, Zheng L, Zhao M, Huang M. Improved protein production in yeast using cell engineering with genes related to a key factor in the unfolded protein response. Metab Eng 2023; 77:152-161. [PMID: 37044356 DOI: 10.1016/j.ymben.2023.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 04/08/2023] [Accepted: 04/09/2023] [Indexed: 04/14/2023]
Abstract
The yeast Saccharomyces cerevisiae is a widely used cell factory for protein production. Increasing the protein production capacity of a yeast strain may be beneficial for obtaining recombinant proteins as a product or exerting its competence in consolidated bioprocessing. However, heterologous protein expression usually imposes stress on cells. Improving the cell's ability to cope with stress enhances protein yield. HAC1 is a key transcription factor in the unfolded protein response (UPR). In this study, several genes related to the UPR signal pathway, including unfolded protein sensing, HAC1 mRNA splicing, mRNA ligation, mRNA decay, translation, and Hac1p degradation, were selected as targets to engineer yeast strains. The final engineered strain produced α-amylase 3.3-fold, and human serum albumin 15.3-fold, greater than that of the control strain. Key regulation and metabolic network changes in the engineered strains were identified by transcriptome analysis and physiological characterizations. This study demonstrated that cell engineering with genes relevant to the key node HAC1 in UPR increased protein secretion substantially. The verified genetic modifications of this study provide useful targets in the construction of yeast cell factories for efficient protein production.
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Affiliation(s)
- Yeping Lin
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China; Guangdong Food Green Processing and Nutrition Regulation Technologies Research Center, Guangzhou, 510650, China
| | - Yunzi Feng
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China; Guangdong Food Green Processing and Nutrition Regulation Technologies Research Center, Guangzhou, 510650, China
| | - Lin Zheng
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China; Guangdong Food Green Processing and Nutrition Regulation Technologies Research Center, Guangzhou, 510650, China
| | - Mouming Zhao
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China; Guangdong Food Green Processing and Nutrition Regulation Technologies Research Center, Guangzhou, 510650, China
| | - Mingtao Huang
- School of Food Science and Engineering, South China University of Technology, Guangzhou, 510641, China; Guangdong Food Green Processing and Nutrition Regulation Technologies Research Center, Guangzhou, 510650, China.
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5
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Matabishi-Bibi L, Challal D, Barucco M, Libri D, Babour A. Termination of the unfolded protein response is guided by ER stress-induced HAC1 mRNA nuclear retention. Nat Commun 2022; 13:6331. [PMID: 36284099 PMCID: PMC9596429 DOI: 10.1038/s41467-022-34133-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 10/14/2022] [Indexed: 12/25/2022] Open
Abstract
Cellular homeostasis is maintained by surveillance mechanisms that intervene at virtually every step of gene expression. In the nucleus, the yeast chromatin remodeler Isw1 holds back maturing mRNA ribonucleoparticles to prevent their untimely export, but whether this activity operates beyond quality control of mRNA biogenesis to regulate gene expression is unknown. Here, we identify the mRNA encoding the central effector of the unfolded protein response (UPR) HAC1, as an Isw1 RNA target. The direct binding of Isw1 to the 3' untranslated region of HAC1 mRNA restricts its nuclear export and is required for accurate UPR abatement. Accordingly, ISW1 inactivation sensitizes cells to endoplasmic reticulum (ER) stress while its overexpression reduces UPR induction. Our results reveal an unsuspected mechanism, in which binding of ER-stress induced Isw1 to HAC1 mRNA limits its nuclear export, providing a feedback loop that fine-tunes UPR attenuation to guarantee homeostatic adaptation to ER stress.
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Affiliation(s)
- Laura Matabishi-Bibi
- grid.508487.60000 0004 7885 7602Univ Paris Diderot, Sorbonne Paris Cité, INSERM U944, CNRS UMR7212, Hôpital St. Louis 1, Avenue Claude Vellefaux, 75475 Paris Cedex 10, France
| | - Drice Challal
- grid.457334.20000 0001 0667 2738Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Mara Barucco
- grid.461913.80000 0001 0676 2143Institut Jacques Monod, Univ Paris Diderot, Sorbonne Paris Cité, CNRS, Bâtiment Buffon, 15 rue Hélène Brion, 75205 Paris Cedex 13, France
| | - Domenico Libri
- grid.429192.50000 0004 0599 0285Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Anna Babour
- grid.508487.60000 0004 7885 7602Univ Paris Diderot, Sorbonne Paris Cité, INSERM U944, CNRS UMR7212, Hôpital St. Louis 1, Avenue Claude Vellefaux, 75475 Paris Cedex 10, France
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6
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Fu F, Doroudgar S. IRE1/XBP1 and Endoplasmic Reticulum Signaling – From Basic to Translational Research for Cardiovascular Disease. CURRENT OPINION IN PHYSIOLOGY 2022; 28. [DOI: 10.1016/j.cophys.2022.100552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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7
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Zhou Z, Wang Q, Michalak M. Inositol Requiring Enzyme (IRE), a multiplayer in sensing endoplasmic reticulum stress. Anim Cells Syst (Seoul) 2022; 25:347-357. [PMID: 35059134 PMCID: PMC8765250 DOI: 10.1080/19768354.2021.2020901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Zhixin Zhou
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - Qian Wang
- Department of Biochemistry, University of Alberta, Edmonton, Canada
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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8
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Chen L, Tu L, Yang G, Banfield DK. Remodeling-defective GPI-anchored proteins on the plasma membrane activate the spindle assembly checkpoint. Cell Rep 2021; 37:110120. [PMID: 34965437 DOI: 10.1016/j.celrep.2021.110120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 10/18/2021] [Accepted: 11/19/2021] [Indexed: 01/15/2023] Open
Abstract
Newly synthesized glycosylphosphatidylinositol-anchored proteins (GPI-APs) undergo extensive remodeling prior to transport to the plasma membrane. GPI-AP remodeling events serve as quality assurance signatures, and complete remodeling of the anchor functions as a transport warrant. Using a genetic approach in yeast cells, we establish that one remodeling event, the removal of ethanolamine-phosphate from mannose 2 via Ted1p (yPGAP5), is essential for cell viability in the absence of the Golgi-localized putative phosphodiesterase Dcr2p. While GPI-APs in which mannose 2 has not been remodeled in dcr2 ted1-deficient cells can still be delivered to the plasma membrane, their presence elicits a unique stress response. Stress is sensed by Mid2p, a constituent of the cell wall integrity pathway, whereupon signal promulgation culminates in activation of the spindle assembly checkpoint. Our results are consistent with a model in which cellular stress response and chromosome segregation checkpoint pathways are functionally interconnected.
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Affiliation(s)
- Li Chen
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, SAR of China
| | - Linna Tu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, SAR of China
| | - Gege Yang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, SAR of China
| | - David K Banfield
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, SAR of China.
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9
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The Unfolded Protein Response: An Overview. BIOLOGY 2021; 10:biology10050384. [PMID: 33946669 PMCID: PMC8146082 DOI: 10.3390/biology10050384] [Citation(s) in RCA: 156] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/23/2021] [Accepted: 04/27/2021] [Indexed: 12/11/2022]
Abstract
Simple Summary The unfolded protein response (UPR) is the cells’ way of maintaining the balance of protein folding in the endoplasmic reticulum, which is the section of the cell designated for folding proteins with specific destinations such as other organelles or to be secreted by the cell. The UPR is activated when unfolded proteins accumulate in the endoplasmic reticulum. This accumulation puts a greater load on the molecules in charge of folding the proteins, and therefore the UPR works to balance this by lowering the number of unfolded proteins present in the cell. This is done in multiple ways, such as lowering the number of proteins that need to be folded; increasing the folding ability of the endoplasmic reticulum and by removing some of the unfolded proteins which take longer to fold. If the UPR is successful at reducing the number of unfolded proteins, the UPR is inactivated and the cells protein folding balance is returned to normal. However, if the UPR is unsuccessful, then this can lead to cell death. Abstract The unfolded protein response is the mechanism by which cells control endoplasmic reticulum (ER) protein homeostasis. Under normal conditions, the UPR is not activated; however, under certain stresses, such as hypoxia or altered glycosylation, the UPR can be activated due to an accumulation of unfolded proteins. The activation of the UPR involves three signaling pathways, IRE1, PERK and ATF6, which all play vital roles in returning protein homeostasis to levels seen in non-stressed cells. IRE1 is the best studied of the three pathways, as it is the only pathway present in Saccharomyces cerevisiae. This pathway involves spliceosome independent splicing of HAC1 or XBP1 in yeast and mammalians cells, respectively. PERK limits protein synthesis, therefore reducing the number of new proteins requiring folding. ATF6 is translocated and proteolytically cleaved, releasing a NH2 domain fragment which is transported to the nucleus and which affects gene expression. If the UPR is unsuccessful at reducing the load of unfolded proteins in the ER and the UPR signals remain activated, this can lead to programmed cell death.
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10
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Szabó K, Miskei M, Farkas I, Dombrádi V. The phosphatome of opportunistic pathogen Candida species. FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2020.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Wang P, Ye Z, Banfield DK. A novel mechanism for the retention of Golgi membrane proteins mediated by the Bre5p/Ubp3p deubiquitinase complex. Mol Biol Cell 2020; 31:2139-2155. [PMID: 32673164 PMCID: PMC7530903 DOI: 10.1091/mbc.e20-03-0168] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The mechanisms employed in the retention of Golgi resident membrane proteins are diverse and include features such as the composition and length of the protein’s transmembrane domain and motifs that mediate direct or indirect associations with COPI-coatomer. However, in sum the current compendium of mechanisms cannot account for the localization of all Golgi membrane proteins, and this is particularly the case for proteins such as the glycosyltransferases. Here we describe a novel mechanism that mediates the steady-state retention of a subset of glycosyltransferases in the Golgi of budding yeast cells. This mechanism is mediated by a deubiquitinase complex composed of Bre5p and Ubp3p. We show that in the absence of this deubiquitinase certain glycosyltransferases are mislocalized to the vacuole, where they are degraded. We also show that Bre5p/Ubp3p clients bind to COPI-coatomer via a series of positively charged amino acids in their cytoplasmically exposed N-termini. Furthermore, we identify two proteins (Ktr3p and Mnn4p) that show a requirement for both Bre5p/Ubp3p as well as the COPI-coatomer–affiliated sorting receptor Vps74p. We also establish that some proteins show a nutrient-dependent role for Vps74p in their Golgi retention. This study expands the repertoire of mechanisms mediating the retention of Golgi membrane proteins.
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Affiliation(s)
- Peng Wang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ziyun Ye
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - David K Banfield
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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12
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Riaz TA, Junjappa RP, Handigund M, Ferdous J, Kim HR, Chae HJ. Role of Endoplasmic Reticulum Stress Sensor IRE1α in Cellular Physiology, Calcium, ROS Signaling, and Metaflammation. Cells 2020; 9:E1160. [PMID: 32397116 PMCID: PMC7290600 DOI: 10.3390/cells9051160] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 04/27/2020] [Accepted: 05/06/2020] [Indexed: 12/14/2022] Open
Abstract
Inositol-requiring transmembrane kinase endoribonuclease-1α (IRE1α) is the most prominent and evolutionarily conserved unfolded protein response (UPR) signal transducer during endoplasmic reticulum functional upset (ER stress). A IRE1α signal pathway arbitrates yin and yang of cellular fate in objectionable conditions. It plays several roles in fundamental cellular physiology as well as in several pathological conditions such as diabetes, obesity, inflammation, cancer, neurodegeneration, and in many other diseases. Thus, further understanding of its molecular structure and mechanism of action during different cell insults helps in designing and developing better therapeutic strategies for the above-mentioned chronic diseases. In this review, recent insights into structure and mechanism of activation of IRE1α along with its complex regulating network were discussed in relation to their basic cellular physiological function. Addressing different binding partners that can modulate IRE1α function, UPRosome triggers different downstream pathways depending on the cellular backdrop. Furthermore, IRE1α are in normal cell activities outside the dominion of ER stress and activities under the weather of inflammation, diabetes, and obesity-related metaflammation. Thus, IRE1 as an ER stress sensor needs to be understood from a wider perspective for comprehensive functional meaning, which facilitates us with assembling future needs and therapeutic benefits.
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Affiliation(s)
- Thoufiqul Alam Riaz
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Raghu Patil Junjappa
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
| | - Mallikarjun Handigund
- Department of Laboratory Medicine, Jeonbuk National University, Medical School, Jeonju 54907, Korea;
| | - Jannatul Ferdous
- Department of Radiology and Research Institute of Clinical Medicine of Jeonbuk National University, Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Korea;
| | - Hyung-Ryong Kim
- College of Dentistry, Dankook University, Cheonan 31116, Korea
| | - Han-Jung Chae
- Department of Pharmacology, School of Medicine, Institute of New Drug Development, Jeonbuk National University, Jeonju 54907, Korea; (T.A.R.); (R.P.J.)
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13
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Xia X. Translation Control of HAC1 by Regulation of Splicing in Saccharomyces cerevisiae. Int J Mol Sci 2019; 20:ijms20122860. [PMID: 31212749 PMCID: PMC6627864 DOI: 10.3390/ijms20122860] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 05/30/2019] [Accepted: 06/10/2019] [Indexed: 12/19/2022] Open
Abstract
Hac1p is a key transcription factor regulating the unfolded protein response (UPR) induced by abnormal accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER) in Saccharomyces cerevisiae. The accumulation of unfolded/misfolded proteins is sensed by protein Ire1p, which then undergoes trans-autophosphorylation and oligomerization into discrete foci on the ER membrane. HAC1 pre-mRNA, which is exported to the cytoplasm but is blocked from translation by its intron sequence looping back to its 5’UTR to form base-pair interaction, is transported to the Ire1p foci to be spliced, guided by a cis-acting bipartite element at its 3’UTR (3’BE). Spliced HAC1 mRNA can be efficiently translated. The resulting Hac1p enters the nucleus and activates, together with coactivators, a large number of genes encoding proteins such as protein chaperones to restore and maintain ER homeostasis and secretary protein quality control. This review details the translation regulation of Hac1p production, mediated by the nonconventional splicing, in the broad context of translation control and summarizes the evolution and diversification of the UPR signaling pathway among fungal, metazoan and plant lineages.
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Affiliation(s)
- Xuhua Xia
- Department of Biology, University of Ottawa, Marie-Curie Private, Ottawa, ON K1N 9A7, Canada.
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14
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Tavernier Q, Bennana E, Poindessous V, Schaeffer C, Rampoldi L, Pietrancosta N, Pallet N. Regulation of IRE1 RNase activity by the Ribonuclease inhibitor 1 (RNH1). Cell Cycle 2018; 17:1901-1916. [PMID: 30109813 DOI: 10.1080/15384101.2018.1506655] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Adaptation to endoplasmic reticulum (ER) stress depends on the activation of the sensor inositol-requiring enzyme 1α (IRE1), an endoribonuclease that splices the mRNA of the transcription factor XBP1 (X-box-binding protein 1). To better understand the protein network that regulates the activity of the IRE1 pathway, we systematically screened the proteins that interact with IRE1 and identified a ribonuclease inhibitor called ribonuclease/angiogenin inhibitor 1 (RNH1). RNH1 is a leucine-rich repeat domains-containing protein that binds to and inhibits ribonucleases. Immunoprecipitation experiments confirmed this interaction. Docking experiments indicated that RNH1 physically interacts with IRE1 through its cytosolic RNase domain. Upon ER stress, the interaction of RNH1 with IRE1 in the ER increased at the expense of the nuclear pool of RNH1. Inhibition of RNH1 expression using siRNA mediated RNA interference upon ER stress led to an increased splicing activity of XBP1. Modulation of IRE1 RNase activity by RNH1 was recapitulated in a cell-free system, suggesting direct regulation of IRE1 by RNH. We conclude that RNH1 attenuates the activity of IRE1 by interacting with its ribonuclease domain. These findings have implications for understanding the molecular mechanism by which IRE1 signaling is attenuated upon ER stress.
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Affiliation(s)
- Quentin Tavernier
- a Institut National de la Santé et de la Recherche Médicale (INSERM) U1147 , Paris , France.,b Paris Descartes University , Paris , France
| | - Evangeline Bennana
- b Paris Descartes University , Paris , France.,c 3P5 Proteomic facility, COMUE Sorbonne Paris Cité , Université Paris Descartes , Paris , France
| | - Virginie Poindessous
- a Institut National de la Santé et de la Recherche Médicale (INSERM) U1147 , Paris , France.,b Paris Descartes University , Paris , France
| | - Celine Schaeffer
- d Molecular Genetics of Renal Disorders Unit, Division of Genetics and Cell Biology , IRCCS San Raffaele Scientific Institute , Milan , Italy
| | - Luca Rampoldi
- d Molecular Genetics of Renal Disorders Unit, Division of Genetics and Cell Biology , IRCCS San Raffaele Scientific Institute , Milan , Italy
| | - Nicolas Pietrancosta
- b Paris Descartes University , Paris , France.,e Centre National pour la Recherche Scientifique (CNRS) U8601 , Paris , France.,f Team Chemistry and Biology, Modeling & Immunology for Therapy , CBMIT, 2MI Platform , Paris , France
| | - Nicolas Pallet
- a Institut National de la Santé et de la Recherche Médicale (INSERM) U1147 , Paris , France.,b Paris Descartes University , Paris , France.,g Clinical Chemistry Department , Hôpital Européen Gorges Pompidou, APHP , Paris , France.,h Plate-forme Proteomique 3P5 , Universite Paris Descartes, Sorbonne Paris Cite , Paris , France
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15
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Bypass of Activation Loop Phosphorylation by Aspartate 836 in Activation of the Endoribonuclease Activity of Ire1. Mol Cell Biol 2017; 37:MCB.00655-16. [PMID: 28559428 PMCID: PMC5533888 DOI: 10.1128/mcb.00655-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 05/22/2017] [Indexed: 12/18/2022] Open
Abstract
The bifunctional protein kinase-endoribonuclease Ire1 initiates splicing of the mRNA for the transcription factor Hac1 when unfolded proteins accumulate in the endoplasmic reticulum. Activation of Saccharomyces cerevisiae Ire1 coincides with autophosphorylation of its activation loop at S840, S841, T844, and S850. Mass spectrometric analysis of Ire1 expressed in Escherichia coli identified S837 as another potential phosphorylation site in vivo. Mutation of all five potential phosphorylation sites in the activation loop decreased, but did not completely abolish, splicing of HAC1 mRNA, induction of KAR2 and PDI1 mRNAs, and expression of a β-galactosidase reporter activated by Hac1i. Phosphorylation site mutants survive low levels of endoplasmic reticulum stress better than IRE1 deletions strains. In vivo clustering and inactivation of Ire1 are not affected by phosphorylation site mutants. Mutation of D836 to alanine in the activation loop of phosphorylation site mutants nearly completely abolished HAC1 splicing, induction of KAR2, PDI1, and β-galactosidase reporters, and survival of ER stress, but it had no effect on clustering of Ire1. By itself, the D836A mutation does not confer a phenotype. These data argue that D836 can partially substitute for activation loop phosphorylation in activation of the endoribonuclease domain of Ire1.
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16
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Protein kinase Snf1 is involved in the proper regulation of the unfolded protein response in Saccharomyces cerevisiae. Biochem J 2015; 468:33-47. [PMID: 25730376 DOI: 10.1042/bj20140734] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glc7 is the only catalytic subunit of the protein phosphatase type 1 in the yeast S. cerevisiae and, together with its regulatory subunits, is involved in many essential processes. Analysis of the non-essential mutants in the regulatory subunits of Glc7 revealed that the lack of Reg1, and no other subunit, causes hypersensitivity to unfolded protein response (UPR)-inducers, which was concomitant with an augmented UPR element-dependent transcriptional response. The Glc7-Reg1 complex takes part in the regulation of the yeast AMP-activated serine/threonine protein kinase Snf1 in response to glucose. We demonstrate in the present study that the observed phenotypes of reg1 mutant cells are attributable to the inappropriate activation of Snf1. Indeed, growth in the presence of limited concentrations of glucose, where Snf1 is active, or expression of active forms of Snf1 in a wild-type strain increased the sensitivity to the UPR-inducer tunicamycin. Furthermore, reg1 mutant cells showed a sustained HAC1 mRNA splicing and KAR2 mRNA levels during the recovery phase of the UPR, and dysregulation of the Ire1-oligomeric equilibrium. Finally, overexpression of protein phosphatases Ptc2 and Ptc3 alleviated the growth defect of reg1 cells under endoplasmic reticulum (ER) stress conditions. Altogether, our results reveal that Snf1 plays an important role in the attenuation of the UPR, as well as identifying the protein kinase and its effectors as possible pharmacological targets for human diseases that are associated with insufficient UPR activation.
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17
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Deng Y, Srivastava R, Howell SH. Endoplasmic reticulum (ER) stress response and its physiological roles in plants. Int J Mol Sci 2013; 14:8188-212. [PMID: 23591838 PMCID: PMC3645738 DOI: 10.3390/ijms14048188] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 03/19/2013] [Accepted: 04/01/2013] [Indexed: 01/29/2023] Open
Abstract
The endoplasmic reticulum (ER) stress response is a highly conserved mechanism that results from the accumulation of unfolded or misfolded proteins in the ER. The response plays an important role in allowing plants to sense and respond to adverse environmental conditions, such as heat stress, salt stress and pathogen infection. Since the ER is a well-controlled microenvironment for proper protein synthesis and folding, it is highly susceptible to stress conditions. Accumulation of unfolded or misfolded proteins activates a signaling pathway, called the unfolded protein response (UPR), which acts to relieve ER stress and, if unsuccessful, leads to cell death. Plants have two arms of the UPR signaling pathway, an arm involving the proteolytic processing of membrane-associated basic leucine zipper domain (bZIP) transcription factors and an arm involving RNA splicing factor, IRE1, and its mRNA target. These signaling pathways play an important role in determining the cell's fate in response to stress conditions.
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Affiliation(s)
- Yan Deng
- Plant Sciences Institute and Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA; E-Mails: (Y.D.); (R.S.)
| | - Renu Srivastava
- Plant Sciences Institute and Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA; E-Mails: (Y.D.); (R.S.)
| | - Stephen H. Howell
- Plant Sciences Institute and Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA; E-Mails: (Y.D.); (R.S.)
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18
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Lee TH, Bae YH, Kim MD, Seo JH. Overexpression of HAC1 gene increased levels of both intracellular and secreted human kringle fragment in Saccharomyces cerevisiae. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Unfolded protein responses with or without unfolded proteins? Cells 2012; 1:926-50. [PMID: 24710536 PMCID: PMC3901143 DOI: 10.3390/cells1040926] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/15/2012] [Accepted: 10/22/2012] [Indexed: 01/08/2023] Open
Abstract
The endoplasmic reticulum (ER) is the site of secretory protein biogenesis. The ER quality control (QC) machinery, including chaperones, ensures the correct folding of secretory proteins. Mutant proteins and environmental stresses can overwhelm the available QC machinery. To prevent and resolve accumulation of misfolded secretory proteins in the ER, cells have evolved integral membrane sensors that orchestrate the Unfolded Protein Response (UPR). The sensors, Ire1p in yeast and IRE1, ATF6, and PERK in metazoans, bind the luminal ER chaperone BiP during homeostasis. As unfolded secretory proteins accumulate in the ER lumen, BiP releases, and the sensors activate. The mechanisms of activation and attenuation of the UPR sensors have exhibited unexpected complexity. A growing body of data supports a model in which Ire1p, and potentially IRE1, directly bind unfolded proteins as part of the activation process. However, evidence for an unfolded protein-independent mechanism has recently emerged, suggesting that UPR can be activated by multiple modes. Importantly, dysregulation of the UPR has been linked to human diseases including Type II diabetes, heart disease, and cancer. The existence of alternative regulatory pathways for UPR sensors raises the exciting possibility for the development of new classes of therapeutics for these medically important proteins.
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Abstract
The endoplasmic reticulum (ER) controls many important aspects of cellular function, including processing of secreted and membrane proteins, synthesis of membranes, and calcium storage. Maintenance of ER function is controlled through a network of signaling pathways collectively known as the unfolded protein response (UPR). The UPR balances the load of incoming proteins with the folding capacity of the ER and allows cells to adapt to situations that disrupt this balance. This disruption is referred to as ER stress. Although ER stress often arises in pathological situations, the UPR plays a central role in the normal development and function of cells specializing in secretion. Many aspects of this response are conserved broadly across eukaryotes; most organisms use some subset of a group of ER transmembrane proteins to signal to the nucleus and induce a broad transcriptional upregulation of genes involved in ER function. However, new developments in metazoans, plants, and fungi illustrate interesting variations on this theme. Here, we summarize mechanisms for detecting and counteracting ER stress, the role of the UPR in normal secretory cell function, and how these pathways vary across organisms and among different tissues and cell types.
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Affiliation(s)
- Kristin A Moore
- Department of Biology and the Center for Cell and Genome Science, University of Utah, Salt Lake City, Utah 84112-0840, USA
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21
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Ota A, Wang Y. Cdc37/Hsp90 protein-mediated regulation of IRE1α protein activity in endoplasmic reticulum stress response and insulin synthesis in INS-1 cells. J Biol Chem 2011; 287:6266-74. [PMID: 22199355 DOI: 10.1074/jbc.m111.331264] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
IRE1α is an endoplasmic reticulum (ER) localized signaling molecule critical for unfolded protein response. During ER stress, IRE1α activation is induced by oligomerization and autophosphorylation in its cytosolic domain, a process triggered by dissociation of an ER luminal chaperone, binding immunoglobulin-protein (BiP), from IRE1α. In addition, inhibition of a cytosolic chaperone protein Hsp90 also induces IRE1α oligomerization and activation in the absence of an ER stressor. Here, we report that the Hsp90 cochaperone Cdc37 directly interacts with IRE1α through a highly conserved cytosolic motif of IRE1α. Cdc37 knockdown or disruption of Cdc37 interaction with IRE1α significantly increased basal IRE1α activity. In INS-1 cells, Hsp90 inhibition and disruption of IRE1α-Cdc37 interaction both induced an ER stress response and impaired insulin synthesis and secretion. These data suggest that Cdc37-mediated direct interaction between Hsp90/Cdc37 and an IRE1α cytosolic motif is important to maintain basal IRE1α activity and contributes to normal protein homeostasis and unfolded protein response under physiological stimulation.
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Affiliation(s)
- Asuka Ota
- Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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22
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A genome-wide immunodetection screen in S. cerevisiae uncovers novel genes involved in lysosomal vacuole function and morphology. PLoS One 2011; 6:e23696. [PMID: 21912603 PMCID: PMC3166051 DOI: 10.1371/journal.pone.0023696] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 07/22/2011] [Indexed: 11/19/2022] Open
Abstract
Vacuoles of yeast Saccharomyces cerevisiae are functionally analogous to mammalian lysosomes. Both are cellular organelles responsible for macromolecular degradation, ion/pH homeostasis, and stress survival. We hypothesized that undefined gene functions remain at post-endosomal stage of vacuolar events and performed a genome-wide screen directed at such functions at the late endosome and vacuole interface – ENV genes. The immunodetection screen was designed to identify mutants that internally accumulate precursor form of the vacuolar hydrolase carboxypeptidase Y (CPY). Here, we report the uncovering and initial characterizations of twelve ENV genes. The small size of the collection and the lack of genes previously identified with vacuolar events are suggestive of the intended exclusive functional interface of the screen. Most notably, the collection includes four novel genes ENV7, ENV9, ENV10, and ENV11, and three genes previously linked to mitochondrial processes – MAM3, PCP1, PPE1. In all env mutants, vesicular trafficking stages were undisturbed in live cells as assessed by invertase and active α-factor secretion, as well as by localization of the endocytic fluorescent marker FM4-64 to the vacuole. Several mutants exhibit defects in stress survival functions associated with vacuoles. Confocal fluorescence microscopy revealed the collection to be significantly enriched in vacuolar morphologies suggestive of fusion and fission defects. These include the unique phenotype of lumenal vesicles within vacuoles in the novel env9Δ mutant and severely fragmented vacuoles upon deletion of GET4, a gene recently implicated in tail anchored membrane protein insertion. Thus, our results establish new gene functions in vacuolar function and morphology, and suggest a link between vacuolar and mitochondrial events.
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23
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Tomecki R, Dziembowski A. Novel endoribonucleases as central players in various pathways of eukaryotic RNA metabolism. RNA (NEW YORK, N.Y.) 2010; 16:1692-1724. [PMID: 20675404 PMCID: PMC2924532 DOI: 10.1261/rna.2237610] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
For a long time it has been assumed that the decay of RNA in eukaryotes is mainly carried out by exoribonucleases, which is in contrast to bacteria, where endoribonucleases are well documented to initiate RNA degradation. In recent years, several as yet unknown endonucleases have been described, which has changed our view on eukaryotic RNA metabolism. Most importantly, it was shown that the primary eukaryotic 3' --> 5' exonuclease, the exosome complex has the ability to endonucleolytically cleave its physiological RNA substrates, and novel endonucleases involved in both nuclear and cytoplasmic RNA surveillance pathways were discovered concurrently. In addition, endoribonucleases responsible for long-known processing steps in the maturation pathways of various RNA classes were recently identified. Moreover, one of the most intensely studied RNA decay pathways--RNAi--is controlled and stimulated by the action of different endonucleases. Furthermore, endoribonucleolytic cleavages executed by various enzymes are also the hallmark of RNA degradation and processing in plant chloroplasts. Finally, multiple context-specific endoribonucleases control qualitative and/or quantitative changes of selected transcripts under particular conditions in different eukaryotic organisms. The aim of this review is to discuss the impact of all of these discoveries on our current understanding of eukaryotic RNA metabolism.
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Affiliation(s)
- Rafal Tomecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, University of Warsaw, 02-106 Warsaw, Poland
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24
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Qiu Y, Mao T, Zhang Y, Shao M, You J, Ding Q, Chen Y, Wu D, Xie D, Lin X, Gao X, Kaufman RJ, Li W, Liu Y. A crucial role for RACK1 in the regulation of glucose-stimulated IRE1alpha activation in pancreatic beta cells. Sci Signal 2010; 3:ra7. [PMID: 20103773 PMCID: PMC2940714 DOI: 10.1126/scisignal.2000514] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Autophosphorylation of inositol-requiring enzyme 1alpha (IRE1alpha) is required for its activation, which elicits the cellular unfolded protein response (UPR) and is functionally connected with insulin biosynthesis in pancreatic beta cells. We found that the scaffold protein receptor for activated C-kinase 1 (RACK1) interacted with IRE1alpha in a glucose-stimulated or endoplasmic reticulum (ER) stress-responsive manner in pancreatic beta cells and primary islets. RACK1 mediated the glucose-inducible assembly of a complex containing IRE1alpha, RACK1, and protein phosphatase 2A (PP2A) to promote dephosphorylation of IRE1alpha by PP2A, thereby inhibiting glucose-stimulated IRE1alpha activation and attenuating IRE1alpha-dependent increases in insulin production. Moreover, IRE1alpha activation was increased and RACK1 abundance was decreased in a mouse model of diabetes. Thus, our findings demonstrate that RACK1 functions as a key component in regulating the IRE1alpha signaling pathway in pancreatic beta cells.
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Affiliation(s)
- Yifu Qiu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Ting Mao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Yongliang Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Mengle Shao
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Jia You
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Qiurong Ding
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Yan Chen
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Dongmei Wu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Dong Xie
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Xu Lin
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Xiang Gao
- Model Animal Research Center, Nanjing University, Nanjing 210093, China
| | - Randal J. Kaufman
- Department of Biological Chemistry and Internal Medicine, Howard Hughes Medical Institute, University of Michigan Medical Center, Ann Arbor, Michigan 48105, USA
| | - Wenjun Li
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
| | - Yong Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences; Graduate School of the Chinese Academy of Sciences; Shanghai 200031, China
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25
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26
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Christis C, Lubsen NH, Braakman I. Protein folding includes oligomerization - examples from the endoplasmic reticulum and cytosol. FEBS J 2008; 275:4700-27. [DOI: 10.1111/j.1742-4658.2008.06590.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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27
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Abstract
Stress within the endoplasmic reticulum (ER) induces a sophisticated network of pathways termed the unfolded protein response (UPR), which is mediated through the ER transmembrane sensors PERK, ATF6, and IRE1. The UPR coordinates the temporary downregulation of protein translation, the upregulation of ER chaperones and folding machinery, and the enhanced expression of components necessary for ER-associated degradation (ERAD) essential for decreasing ER stress by clearing terminally misfolded proteins from the ER. Repetitive but futile folding attempts not only prolong ER stress but can also result in reactive oxygen species (ROS) generation, both of which may result in cell death. Additional mechanisms for decreasing stress and the protein load in the ER have been recently revealed. They include a newly identified function of IRE1 in degradation of select secretory protein mRNAs, a "preemptive" quality control responsible for averting translocation of select secretory proteins into the ER, upregulation of forward trafficking to allow misfolded proteins with intact exit signals to exit the ER, and upregulation of autophagy. The saturation or failure of some or all of these mechanisms can result in cell death and disease, including diabetes and a number of late-onset neurologic diseases.
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Affiliation(s)
- Margaret M Kincaid
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri, USA
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28
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Pathak R, Blank HM, Guo J, Ellis S, Polymenis M. The Dcr2p phosphatase destabilizes Sic1p in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2007; 361:700-4. [PMID: 17673172 PMCID: PMC2031908 DOI: 10.1016/j.bbrc.2007.07.092] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2007] [Accepted: 07/19/2007] [Indexed: 01/20/2023]
Abstract
Initiation of cell division is controlled by an irreversible switch. In Saccharomyces cerevisiae degradation of the Sic1p protein, an inhibitor of mitotic cyclin/cyclin-dependent kinase complexes, takes place before initiation of DNA replication, at a point called START. Sic1p is phosphorylated by multiple kinases, which can differentially affect the stability of Sic1p. How phosphorylations that stabilize Sic1p are reversed is unknown. Here we show that the Dcr2p phosphatase functionally and physically interacts with Sic1p. Over-expression of Dcr2p destabilizes Sic1p and leads to phenotypes associated with destabilized Sic1p, such as genome instability. Our results identify a novel factor that affects the stability of Sic1p, possibly contributing to mechanisms that trigger initiation of cell division.
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Affiliation(s)
| | | | | | | | - Michael Polymenis
- *To whom correspondence should be addressed. Tel: 1-979-458-3259; FAX: 1-979-845-4946, e-mail:
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29
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Current awareness on yeast. Yeast 2007. [DOI: 10.1002/yea.1328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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30
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Rubenstein EM, Schmidt MC. Mechanisms regulating the protein kinases of Saccharomyces cerevisiae. EUKARYOTIC CELL 2007; 6:571-83. [PMID: 17337635 PMCID: PMC1865659 DOI: 10.1128/ec.00026-07] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Eric M Rubenstein
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, W1247 Biomedical Science Tower, Pittsburgh, PA 15261, USA
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