1
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Cho B, Shin M, Chang E, Son S, Shin I, Shim J. S-nitrosylation-triggered unfolded protein response maintains hematopoietic progenitors in Drosophila. Dev Cell 2024; 59:1075-1090.e6. [PMID: 38521056 DOI: 10.1016/j.devcel.2024.02.013] [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: 07/18/2023] [Revised: 11/27/2023] [Accepted: 02/29/2024] [Indexed: 03/25/2024]
Abstract
The Drosophila lymph gland houses blood progenitors that give rise to myeloid-like blood cells. Initially, blood progenitors proliferate, but later, they become quiescent to maintain multipotency before differentiation. Despite the identification of various factors involved in multipotency maintenance, the cellular mechanism controlling blood progenitor quiescence remains elusive. Here, we identify the expression of nitric oxide synthase in blood progenitors, generating nitric oxide for post-translational S-nitrosylation of protein cysteine residues. S-nitrosylation activates the Ire1-Xbp1-mediated unfolded protein response, leading to G2 cell-cycle arrest. Specifically, we identify the epidermal growth factor receptor as a target of S-nitrosylation, resulting in its retention within the endoplasmic reticulum and blockade of its receptor function. Overall, our findings highlight developmentally programmed S-nitrosylation as a critical mechanism that induces protein quality control in blood progenitors, maintaining their undifferentiated state by inhibiting cell-cycle progression and rendering them unresponsive to paracrine factors.
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Affiliation(s)
- Bumsik Cho
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea; Research Institute for Natural Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Mingyu Shin
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Eunji Chang
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Seogho Son
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Incheol Shin
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea; Research Institute for Natural Science, Hanyang University, Seoul 04763, Republic of Korea; Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea
| | - Jiwon Shim
- Department of Life Science, College of Natural Science, Hanyang University, Seoul 04763, Republic of Korea; Research Institute for Natural Science, Hanyang University, Seoul 04763, Republic of Korea; Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea; Hanyang Institute of Bioscience and Biotechnology, Hanyang University, Seoul 04763, Republic of Korea.
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2
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Zhang SX, Wang JJ, Starr CR, Lee EJ, Park KS, Zhylkibayev A, Medina A, Lin JH, Gorbatyuk M. The endoplasmic reticulum: Homeostasis and crosstalk in retinal health and disease. Prog Retin Eye Res 2024; 98:101231. [PMID: 38092262 PMCID: PMC11056313 DOI: 10.1016/j.preteyeres.2023.101231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
The endoplasmic reticulum (ER) is the largest intracellular organelle carrying out a broad range of important cellular functions including protein biosynthesis, folding, and trafficking, lipid and sterol biosynthesis, carbohydrate metabolism, and calcium storage and gated release. In addition, the ER makes close contact with multiple intracellular organelles such as mitochondria and the plasma membrane to actively regulate the biogenesis, remodeling, and function of these organelles. Therefore, maintaining a homeostatic and functional ER is critical for the survival and function of cells. This vital process is implemented through well-orchestrated signaling pathways of the unfolded protein response (UPR). The UPR is activated when misfolded or unfolded proteins accumulate in the ER, a condition known as ER stress, and functions to restore ER homeostasis thus promoting cell survival. However, prolonged activation or dysregulation of the UPR can lead to cell death and other detrimental events such as inflammation and oxidative stress; these processes are implicated in the pathogenesis of many human diseases including retinal disorders. In this review manuscript, we discuss the unique features of the ER and ER stress signaling in the retina and retinal neurons and describe recent advances in the research to uncover the role of ER stress signaling in neurodegenerative retinal diseases including age-related macular degeneration, inherited retinal degeneration, achromatopsia and cone diseases, and diabetic retinopathy. In some chapters, we highlight the complex interactions between the ER and other intracellular organelles focusing on mitochondria and illustrate how ER stress signaling regulates common cellular stress pathways such as autophagy. We also touch upon the integrated stress response in retinal degeneration and diabetic retinopathy. Finally, we provide an update on the current development of pharmacological agents targeting the UPR response and discuss some unresolved questions and knowledge gaps to be addressed by future research.
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Affiliation(s)
- Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States.
| | - Josh J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Christopher R Starr
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eun-Jin Lee
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Assylbek Zhylkibayev
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andy Medina
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, United States
| | - Jonathan H Lin
- Department of Ophthalmology and Byers Eye Institute, Stanford University, Stanford, CA, United States; VA Palo Alto Healthcare System, Palo Alto, CA, United States; Department of Pathology, Stanford University, Stanford, CA, United States
| | - Marina Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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3
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Zheng J, Guo Y, Shi C, Yang S, Xu W, Ma X. Differential Ire1 determines loser cell fate in tumor-suppressive cell competition. Cell Rep 2023; 42:113303. [PMID: 37924514 DOI: 10.1016/j.celrep.2023.113303] [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: 02/07/2023] [Revised: 08/31/2023] [Accepted: 10/03/2023] [Indexed: 11/06/2023] Open
Abstract
Tumor-suppressive cell competition (TSCC) is a conserved surveillance mechanism in which neighboring cells actively eliminate oncogenic cells. Despite overwhelming studies showing that the unfolded protein response (UPR) is dysregulated in various tumors, it remains debatable whether the UPR restrains or promotes tumorigenesis. Here, using Drosophila eye epithelium as a model, we uncover a surprising decisive role of the Ire1 branch of the UPR in regulating cell polarity gene scribble (scrib) loss-induced TSCC. Both mutation and hyperactivation of Ire1 accelerate elimination of scrib clones via inducing apoptosis and autophagy, respectively. Unexpectedly, relative Ire1 activity is also crucial for determining loser cell fate, as dysregulating Ire1 signaling in the surrounding healthy cells reversed the "loser" status of scrib clones by decreasing their apoptosis. Furthermore, we show that Ire1 is required for cell competition in mammalian cells. Together, these findings provide molecular insights into scrib-mediated TSCC and highlight Ire1 as a key determinant of loser cell fate.
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Affiliation(s)
- Jiadong Zheng
- Fudan University, Shanghai 200433, China; Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China
| | - Yifan Guo
- Fudan University, Shanghai 200433, China; Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China
| | - Changyi Shi
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China
| | - Shuai Yang
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China
| | - Wenyan Xu
- Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China.
| | - Xianjue Ma
- Fudan University, Shanghai 200433, China; Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China.
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4
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Ottens F, Efstathiou S, Hoppe T. Cutting through the stress: RNA decay pathways at the endoplasmic reticulum. Trends Cell Biol 2023:S0962-8924(23)00236-2. [PMID: 38008608 DOI: 10.1016/j.tcb.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 11/28/2023]
Abstract
The endoplasmic reticulum (ER) is central to the processing of luminal, transmembrane, and secretory proteins, and maintaining a functional ER is essential for organismal physiology and health. Increased protein-folding load on the ER causes ER stress, which activates quality control mechanisms to restore ER function and protein homeostasis. Beyond protein quality control, mRNA decay pathways have emerged as potent ER fidelity regulators, but their mechanistic roles in ER quality control and their interrelationships remain incompletely understood. Herein, we review ER-associated RNA decay pathways - including regulated inositol-requiring enzyme 1α (IRE1α)-dependent mRNA decay (RIDD), nonsense-mediated mRNA decay (NMD), and Argonaute-dependent RNA silencing - in ER homeostasis, and highlight the intricate coordination of ER-targeted RNA and protein decay mechanisms and their association with antiviral defense.
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Affiliation(s)
- Franziska Ottens
- Institute for Genetics, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Sotirios Efstathiou
- Institute for Genetics, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine and University Hospital of Cologne, Cologne, Germany.
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5
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Mingjie Y, Yair A, Tali G. The RIDD activity of C. elegans IRE1 modifies neuroendocrine signaling in anticipation of environment stress to ensure survival. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552841. [PMID: 37609168 PMCID: PMC10441387 DOI: 10.1101/2023.08.10.552841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Xbp1 splicing and regulated IRE1-dependent RNA decay (RIDD) are two RNase activities of the ER stress sensor IRE1. While Xbp1 splicing has important roles in stress responses and animal physiology, the physiological role(s) of RIDD remain enigmatic. Genetic evidence in C. elegans connects XBP1-independent IRE1 activity to organismal stress adaptation, but whether this is via RIDD, and what are the targets is yet unknown. We show that cytosolic kinase/RNase domain of C. elegans IRE1 is indeed capable of RIDD in human cells, and that sensory neurons use RIDD to signal environmental stress, by degrading mRNA of TGFβ-like growth factor DAF-7. daf-7 was degraded in human cells by both human and worm IRE1 RNAse activity with same efficiency and specificity as Blos1, confirming daf-7 as RIDD substrate. Surprisingly, daf-7 degradation in vivo was triggered by concentrations of ER stressor tunicamycin too low for xbp-1 splicing. Decrease in DAF-7 normally signals food limitation and harsh environment, triggering adaptive changes to promote population survival. Because C. elegans is a bacteriovore, and tunicamycin, like other common ER stressors, is an antibiotic secreted by Streptomyces spp., we asked whether daf-7 degradation by RIDD could signal pending food deprivation. Indeed, pre-emptive tunicamycin exposure increased survival of C. elegans populations under food limiting/high temperature stress, and this protection was abrogated by overexpression of DAF-7. Thus, C. elegans uses stress-inducing metabolites in its environment as danger signals, and employs IRE1's RIDD activity to modulate the neuroendocrine signaling for survival of upcoming environmental challenge.
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Affiliation(s)
- Ying Mingjie
- Department of Biology, Drexel University, Philadelphia, PA
- Department of Pathology and Lab Medicine, The Children's Hospital of Philadelphia and the University of Pennsylvania, Philadelphia, PA, USA
| | - Argon Yair
- Department of Pathology and Lab Medicine, The Children's Hospital of Philadelphia and the University of Pennsylvania, Philadelphia, PA, USA
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6
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Zhao N, Li N, Wang T. PERK prevents rhodopsin degradation during retinitis pigmentosa by inhibiting IRE1-induced autophagy. J Cell Biol 2023; 222:e202208147. [PMID: 37022709 PMCID: PMC10082367 DOI: 10.1083/jcb.202208147] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 01/04/2023] [Accepted: 02/14/2023] [Indexed: 04/07/2023] Open
Abstract
Chronic endoplasmic reticulum (ER) stress is the underlying cause of many degenerative diseases, including autosomal dominant retinitis pigmentosa (adRP). In adRP, mutant rhodopsins accumulate and cause ER stress. This destabilizes wild-type rhodopsin and triggers photoreceptor cell degeneration. To reveal the mechanisms by which these mutant rhodopsins exert their dominant-negative effects, we established an in vivo fluorescence reporter system to monitor mutant and wild-type rhodopsin in Drosophila. By performing a genome-wide genetic screen, we found that PERK signaling plays a key role in maintaining rhodopsin homeostasis by attenuating IRE1 activities. Degradation of wild-type rhodopsin is mediated by selective autophagy of ER, which is induced by uncontrolled IRE1/XBP1 signaling and insufficient proteasome activities. Moreover, upregulation of PERK signaling prevents autophagy and suppresses retinal degeneration in the adRP model. These findings establish a pathological role for autophagy in this neurodegenerative condition and indicate that promoting PERK activity could be used to treat ER stress-related neuropathies, including adRP.
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Affiliation(s)
- Ning Zhao
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Ning Li
- College of Biological Sciences, China Agricultural University, Beijing, China
| | - Tao Wang
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
- College of Biological Sciences, China Agricultural University, Beijing, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
- National Institute of Biological Sciences, Beijing, China
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7
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Rai D, Iwanami M, Takahashi Y, Komuta Y, Aoi N, Umezawa A, Seko Y. Evaluation of photoreceptor-directed fibroblasts derived from retinitis pigmentosa patients with defects in the EYS gene: a possible cost-effective cellular model for mechanism-oriented drug. Stem Cell Res Ther 2022; 13:157. [PMID: 35410372 PMCID: PMC8996485 DOI: 10.1186/s13287-022-02827-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 03/14/2022] [Indexed: 12/15/2022] Open
Abstract
Background The most common gene responsible for autosomal recessive retinitis pigmentosa (RP) is EYS. The manner of decay of genetically defective EYS gene transcripts varies depending on the type of mutation using our cellular model, which consists of induced photoreceptor-directed fibroblasts from EYS-RP patients (EYS-RP cells). However, disease-specific profiles have not been clarified in EYS-RP cells. Herein we investigated comprehensive gene expression patterns and restoration of altered expression by low molecular weight molecules in EYS-RP cells.
Methods Using induced photoreceptor-like cells by CRX, RAX, NeuroD, and OTX2, we employed qRT-PCR and DNA microarray analysis to compare expression levels of disease-related genes in EYS-RP cells. We investigated the effect of antiapoptotic or anti-endoplasmic reticulum (ER) stress/antioxidant reagents on the restoration of altered gene expression. Results Expression levels of phototransduction-related genes (blue opsin, rhodopsin, S-antigen, GNAT1, GNAT2) were lower in EYS-RP cells. CRYGD was extracted by global gene expression analysis, as a downregulated, retina-related and apoptosis-, endoplasmic reticulum (ER) stress- or aging-related gene. Pathway enrichment analysis suggested that “complement and coagulation cascades,” “ECM-receptor interaction” and “PI3K-Akt signaling pathway” could be involved in EYS-RP-associated pathogenesis. Among the matching/overlapping genes involved in those pathways, F2R was suggested as an EYS-RP-associated gene. The downregulation of CRYGD and F2R was completely restored by additional 4-PBA, an inhibitor of ER stress, and partially restored by metformin or NAC. In addition, 4-PBA normalized the expression level of cleaved caspase-3. Conclusions Our cellular model may reflect the ER stress-mediated degenerative retina and serve as a pathogenesis-oriented cost-effective rescue strategy for RP patients. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02827-x.
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Affiliation(s)
- Dilip Rai
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan
| | - Masaki Iwanami
- Department of Ophthalmology, Hospital, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.,Iwanami Eye Clinic, 7-1-3, Tsuchihashi, Miyamae-ku Kawasaki, Tokyo, 216-0005, Japan
| | - Yoriko Takahashi
- Bioscience and Healthcare Engineering Division, Mitsui Knowledge Industry Co., Ltd., 2-7-14 Higashi-Nakano, Nakano-ku, Tokyo, 164-8555, Japan
| | - Yukari Komuta
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.,Division of Bioinformation and Therapeutic Systems, National Defense Medical College, 3 Namiki, Tokorozawa, 359-0042, Japan
| | - Noriyuki Aoi
- Department of Plastic, Oral and Maxillofacial Surgery, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi, Tokyo, 173-8605, Japan.,Miyamasuzaka Clinic, SK Aoyama Bldg. 5F, 1-6-5 Shibuya, Tokyo, 150-0002, Japan
| | - Akihiro Umezawa
- National Center for Child Health and Development, Research Institute, 2-10-1 Okura, Setagaya, 157-8535, Japan
| | - Yuko Seko
- Sensory Functions Section, Research Institute, National Rehabilitation Center for Persons With Disabilities, 4-1 Namiki, Tokorozawa, 359-8555, Japan.
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8
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Pumilio protects Xbp1 mRNA from regulated Ire1-dependent decay. Nat Commun 2022; 13:1587. [PMID: 35332141 PMCID: PMC8948244 DOI: 10.1038/s41467-022-29105-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 02/17/2022] [Indexed: 12/12/2022] Open
Abstract
The unfolded protein response (UPR) maintains homeostasis of the endoplasmic reticulum (ER). Residing in the ER membrane, the UPR mediator Ire1 deploys its cytoplasmic kinase-endoribonuclease domain to activate the key UPR transcription factor Xbp1 through non-conventional splicing of Xbp1 mRNA. Ire1 also degrades diverse ER-targeted mRNAs through regulated Ire1-dependent decay (RIDD), but how it spares Xbp1 mRNA from this decay is unknown. Here, we identify binding sites for the RNA-binding protein Pumilio in the 3′UTR Drosophila Xbp1. In the developing Drosophila eye, Pumilio binds both the Xbp1unspliced and Xbp1spliced mRNAs, but only Xbp1spliced is stabilized by Pumilio. Furthermore, Pumilio displays Ire1 kinase-dependent phosphorylation during ER stress, which is required for its stabilization of Xbp1spliced. hIRE1 can phosphorylate Pumilio directly, and phosphorylated Pumilio protects Xbp1spliced mRNA against RIDD. Thus, Ire1-mediated phosphorylation enables Pumilio to shield Xbp1spliced from RIDD. These results uncover an unexpected regulatory link between an RNA-binding protein and the UPR. In Drosophila, ER-targeted mRNAs are degraded by Ire1-dependent pathway. Here the authors report that the fly mRNA binding protein Pumilio is phosphorylated by Ire1 and binds to Xbp1 mRNA, protecting it from the non-canonical endoribonuclease activity of Ire1.
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9
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Kamemura K, Moriya H, Ukita Y, Okumura M, Miura M, Chihara T. Endoplasmic reticulum proteins Meigo and Gp93 govern dendrite targeting by regulating Toll-6 localization. Dev Biol 2022; 484:30-39. [DOI: 10.1016/j.ydbio.2022.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 12/29/2021] [Accepted: 02/02/2022] [Indexed: 12/15/2022]
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10
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Decoding non-canonical mRNA decay by the endoplasmic-reticulum stress sensor IRE1α. Nat Commun 2021; 12:7310. [PMID: 34911951 PMCID: PMC8674358 DOI: 10.1038/s41467-021-27597-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 11/24/2021] [Indexed: 12/21/2022] Open
Abstract
Inositol requiring enzyme 1 (IRE1) mitigates endoplasmic-reticulum (ER) stress by orchestrating the unfolded-protein response (UPR). IRE1 spans the ER membrane, and signals through a cytosolic kinase-endoribonuclease module. The endoribonuclease generates the transcription factor XBP1s by intron excision between similar RNA stem-loop endomotifs, and depletes select cellular mRNAs through regulated IRE1-dependent decay (RIDD). Paradoxically, in mammals RIDD seems to target only mRNAs with XBP1-like endomotifs, while in flies RIDD exhibits little sequence restriction. By comparing nascent and total IRE1α-controlled mRNAs in human cells, we identify not only canonical endomotif-containing RIDD substrates, but also targets without such motifs-degraded by a process we coin RIDDLE, for RIDD lacking endomotif. IRE1α displays two basic endoribonuclease modalities: highly specific, endomotif-directed cleavage, minimally requiring dimers; and more promiscuous, endomotif-independent processing, requiring phospho-oligomers. An oligomer-deficient IRE1α mutant fails to support RIDDLE in vitro and in cells. Our results advance current mechanistic understanding of the UPR.
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11
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Ricci D, Gidalevitz T, Argon Y. The special unfolded protein response in plasma cells. Immunol Rev 2021; 303:35-51. [PMID: 34368957 DOI: 10.1111/imr.13012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 06/08/2021] [Indexed: 12/11/2022]
Abstract
The high rate of antibody production places considerable metabolic and folding stress on plasma cells (PC). Not surprisingly, they rely on the unfolded protein response (UPR), a universal signaling, and transcriptional network that monitors the health of the secretory pathway and mounts cellular responses to stress. Typically, the UPR utilizes three distinct stress sensors in the ER membrane, each regulating a subset of targets to re-establish homeostasis. PC use a specialized UPR scheme-they preemptively trigger the UPR via developmental signals and suppress two of the sensors, PERK and ATF6, relying on IRE1 alone. The specialized PC UPR program is tuned to the specific needs at every stage of development-from early biogenesis of secretory apparatus, to massive immunoglobulin expression later. Furthermore, the UPR in PC integrates with other pathways essential in a highly secretory cell-mTOR pathway that ensures efficient synthesis, autophagosomes that recycle components of the synthetic machinery, and apoptotic signaling that controls cell fate in the face of excessive folding stress. This specialized PC program is not shared with other secretory cells, for reasons yet to be defined. In this review, we give a perspective into how and why PC need such a unique UPR program.
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Affiliation(s)
- Daniela Ricci
- Department of Pathology and Lab Medicine, The Childrens' Hospital of Philadelphia and the University of Pennsylvania, Philadelphia, PA, USA
| | - Tali Gidalevitz
- Department of Biology, Drexel University, Philadelphia, PA, USA
| | - Yair Argon
- Department of Pathology and Lab Medicine, The Childrens' Hospital of Philadelphia and the University of Pennsylvania, Philadelphia, PA, USA
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12
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Zhang C, van Leeuwen W, Blotenburg M, Aguilera-Gomez A, Brussee S, Grond R, Kampinga HH, Rabouille C. Activation of salt Inducible Kinases, IRE1 and PERK leads to Sec bodies formation in Drosophila S2 cells. J Cell Sci 2021; 134:272062. [PMID: 34350957 PMCID: PMC8445602 DOI: 10.1242/jcs.258685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/21/2021] [Indexed: 11/20/2022] Open
Abstract
The phase separation of the non-membrane bound Sec bodies occurs in Drosophila S2 cells by coalescence of components of the endoplasmic reticulum (ER) exit sites under the stress of amino acid starvation. Here, we address which signaling pathways cause Sec body formation and find that two pathways are critical. The first is the activation of the salt-inducible kinases (SIKs; SIK2 and SIK3) by Na+ stress, which, when it is strong, is sufficient. The second is activation of IRE1 and PERK (also known as PEK in flies) downstream of ER stress induced by the absence of amino acids, which needs to be combined with moderate salt stress to induce Sec body formation. SIK, and IRE1 and PERK activation appear to potentiate each other through the stimulation of the unfolded protein response, a key parameter in Sec body formation. This work shows the role of SIKs in phase transition and re-enforces the role of IRE1 and PERK as a metabolic sensor for the level of circulating amino acids and salt. This article has an associated First Person interview with the first author of the paper. Summary: In S2 cells, the phase-separated Sec bodies form upon the combined activation of salt-inducible kinases, IRE1 and PERK.
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Affiliation(s)
- Chujun Zhang
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht, The Netherlands
| | | | | | | | - Sem Brussee
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht, The Netherlands
| | - Rianne Grond
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht, The Netherlands
| | - Harm H Kampinga
- Department of Biomedical Sciences in Cells and Systems, UMC Groningen, The Netherlands
| | - Catherine Rabouille
- Hubrecht Institute of the KNAW & UMC Utrecht, Utrecht, The Netherlands.,Department of Biomedical Sciences in Cells and Systems, UMC Groningen, The Netherlands.,Section Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, The Netherlands
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13
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Mitra S, Ryoo HD. The role of Ire1 in Drosophila eye pigmentation revealed by an RNase dead allele. Dev Biol 2021; 478:205-211. [PMID: 34265355 DOI: 10.1016/j.ydbio.2021.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 06/25/2021] [Accepted: 07/10/2021] [Indexed: 11/29/2022]
Abstract
Ire1 is an endoplasmic reticulum (ER) transmembrane RNase that cleaves substrate mRNAs to help cells adapt to ER stress. Because there are cell types with physiological ER stress, loss of Ire1 results in metabolic and developmental defects in diverse organisms. In Drosophila, Ire1 mutants show developmental defects at early larval stages and in pupal eye photoreceptor differentiation. These Drosophila studies relied on a single Ire1 loss of function allele with a Piggybac insertion in the coding sequence. Here, we report that an Ire1 allele with a specific impairment in the RNase domain, H890A, unmasks previously unrecognized Ire1 phenotypes in Drosophila eye pigmentation. Specifically, we found that the adult eye pigmentation is altered, and the pigment granules are compromised in Ire1H890A homozygous mosaic eyes. Furthermore, the Ire1H890A mutant eyes had dramatically reduced Rhodopsin-1 protein levels. Drosophila eye pigment granules are most notably associated with late endosome/lysosomal defects. Our results indicate that the loss of Ire1, which would impair ER homeostasis, also results in altered adult eye pigmentation.
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Affiliation(s)
- Sahana Mitra
- Department of Cell Biology, NYU Grossman School of Medicine, 550 First Avenue, New York, NY, 10016, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, NYU Grossman School of Medicine, 550 First Avenue, New York, NY, 10016, USA.
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14
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Zhao P, Huang P, Xu T, Xiang X, Sun Y, Liu J, Yan C, Wang L, Gao J, Cui S, Wang X, Zhan L, Song H, Liu J, Song W, Liu Y. Fat body Ire1 regulates lipid homeostasis through the Xbp1s-FoxO axis in Drosophila. iScience 2021; 24:102819. [PMID: 34381963 PMCID: PMC8333185 DOI: 10.1016/j.isci.2021.102819] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/25/2021] [Accepted: 07/02/2021] [Indexed: 11/24/2022] Open
Abstract
The endoplasmic reticulum (ER)-resident transmembrane protein kinase/RNase Ire1 is a conserved sensor of the cellular unfolded protein response and has been implicated in lipid homeostasis, including lipid synthesis and transport, across species. Here we report a novel catabolic role of Ire1 in regulating lipid mobilization in Drosophila. We found that Ire1 is activated by nutrient deprivation, and, importantly, fat body-specific Ire1 deficiency leads to increased lipid mobilization and sensitizes flies to starvation, whereas fat body Ire1 overexpression results in the opposite phenotypes. Genetic interaction and biochemical analyses revealed that Ire1 regulates lipid mobilization by promoting Xbp1s-associated FoxO degradation and suppressing FoxO-dependent lipolytic programs. Our results demonstrate that Ire1 is a catabolic sensor and acts through the Xbp1s-FoxO axis to hamper the lipolytic response during chronic food deprivation. These findings offer new insights into the conserved Ire1 regulation of lipid homeostasis. Food deprivation systemically activates Ire1 and increases Xbp1 splicing Fat body Ire1-Xbp1s axis regulates lipid mobilization and survival during starvation Ire1-Xbp1s pathway enhances proteasomal degradation of FoxO Fat body Ire1-Xbp1s pathway hampers FoxO-associated lipid mobilization under starvation
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Affiliation(s)
- Peng Zhao
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences; the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Ping Huang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Tongfu Xu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaoxiang Xiang
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Ying Sun
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jingqi Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Cheng Yan
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lei Wang
- Key Laboratory of Molecular Virology and Immunology, Institute Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jiamei Gao
- School of Life Science and Technology, Shanghai Tech University, Shanghai 200031, China
| | - Shang Cui
- Department of Cell Biology, Shandong University School of Medicine, Jinan, China, 250012
| | - Xiangdong Wang
- Department of Cell Biology, Shandong University School of Medicine, Jinan, China, 250012
| | - Lixing Zhan
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Haiyun Song
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jingnan Liu
- School of Life Science and Technology, Shanghai Tech University, Shanghai 200031, China
| | - Wei Song
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan 430071, China
| | - Yong Liu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences; the Institute for Advanced Studies, Wuhan University, Wuhan 430072, China.,Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Wuhan University, Wuhan 430071, China
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15
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Griffiths NW, Del Bel LM, Wilk R, Brill JA. Cellular homeostasis in the Drosophila retina requires the lipid phosphatase Sac1. Mol Biol Cell 2020; 31:1183-1199. [PMID: 32186963 PMCID: PMC7353163 DOI: 10.1091/mbc.e20-02-0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The complex functions of cellular membranes, and thus overall cell physiology, depend on the distribution of crucial lipid species. Sac1 is an essential, conserved, ER-localized phosphatase whose substrate, phosphatidylinositol 4-phosphate (PI4P), coordinates secretory trafficking and plasma membrane function. PI4P from multiple pools is delivered to Sac1 by oxysterol-binding protein and related proteins in exchange for other lipids and sterols, which places Sac1 at the intersection of multiple lipid distribution pathways. However, much remains unknown about the roles of Sac1 in subcellular homeostasis and organismal development. Using a temperature-sensitive allele (Sac1ts), we show that Sac1 is required for structural integrity of the Drosophila retinal floor. The βps-integrin Myospheroid, which is necessary for basal cell adhesion, is mislocalized in Sac1ts retinas. In addition, the adhesion proteins Roughest and Kirre, which coordinate apical retinal cell patterning at an earlier stage, accumulate within Sac1ts retinal cells due to impaired endo-lysosomal degradation. Moreover, Sac1 is required for ER homeostasis in Drosophila retinal cells. Together, our data illustrate the importance of Sac1 in regulating multiple aspects of cellular homeostasis during tissue development.
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Affiliation(s)
- Nigel W Griffiths
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Lauren M Del Bel
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Ronit Wilk
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada
| | - Julie A Brill
- Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
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16
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Dufey E, Bravo-San Pedro JM, Eggers C, González-Quiroz M, Urra H, Sagredo AI, Sepulveda D, Pihán P, Carreras-Sureda A, Hazari Y, Sagredo EA, Gutierrez D, Valls C, Papaioannou A, Acosta-Alvear D, Campos G, Domingos PM, Pedeux R, Chevet E, Alvarez A, Godoy P, Walter P, Glavic A, Kroemer G, Hetz C. Genotoxic stress triggers the activation of IRE1α-dependent RNA decay to modulate the DNA damage response. Nat Commun 2020; 11:2401. [PMID: 32409639 PMCID: PMC7224204 DOI: 10.1038/s41467-020-15694-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 03/12/2020] [Indexed: 02/07/2023] Open
Abstract
The molecular connections between homeostatic systems that maintain both genome integrity and proteostasis are poorly understood. Here we identify the selective activation of the unfolded protein response transducer IRE1α under genotoxic stress to modulate repair programs and sustain cell survival. DNA damage engages IRE1α signaling in the absence of an endoplasmic reticulum (ER) stress signature, leading to the exclusive activation of regulated IRE1α-dependent decay (RIDD) without activating its canonical output mediated by the transcription factor XBP1. IRE1α endoribonuclease activity controls the stability of mRNAs involved in the DNA damage response, impacting DNA repair, cell cycle arrest and apoptosis. The activation of the c-Abl kinase by DNA damage triggers the oligomerization of IRE1α to catalyze RIDD. The protective role of IRE1α under genotoxic stress is conserved in fly and mouse. Altogether, our results uncover an important intersection between the molecular pathways that sustain genome stability and proteostasis. IRE1α plays a key role in the unfolded protein response (UPR) by promoting the unconventional splicing of the XBP1 and the selective cleavage of RNAs. Here the authors report that IRE1α is activated upon the DNA damage response and selectively controls the stability of mRNAs to maintain genome integrity.
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Affiliation(s)
- Estefanie Dufey
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - José Manuel Bravo-San Pedro
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Inserm U1138, Université de Paris, Sorbonne Université, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France
| | - Cristian Eggers
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile.,Center for Genome Regulation, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Matías González-Quiroz
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile.,Proteostasis & Cancer Team, INSERM U1242, University of Rennes 1, Rennes, France.,Centre de Lutte contre le Cancer Eugène Marquis, Rennes, France
| | - Hery Urra
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Alfredo I Sagredo
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Denisse Sepulveda
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Philippe Pihán
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Amado Carreras-Sureda
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Younis Hazari
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile.,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile.,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Eduardo A Sagredo
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Daniela Gutierrez
- Department of Cell & Molecular Biology, Pontificia Universidad Católica de Chile, 8331010, Santiago, Chile
| | - Cristian Valls
- Department of Cell & Molecular Biology, Pontificia Universidad Católica de Chile, 8331010, Santiago, Chile
| | - Alexandra Papaioannou
- Proteostasis & Cancer Team, INSERM U1242, University of Rennes 1, Rennes, France.,Centre de Lutte contre le Cancer Eugène Marquis, Rennes, France
| | - Diego Acosta-Alvear
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA.,Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Gisela Campos
- IfADo-Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, 44139, Dortmund, Germany
| | - Pedro M Domingos
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Rémy Pedeux
- Proteostasis & Cancer Team, INSERM U1242, University of Rennes 1, Rennes, France.,Centre de Lutte contre le Cancer Eugène Marquis, Rennes, France
| | - Eric Chevet
- Proteostasis & Cancer Team, INSERM U1242, University of Rennes 1, Rennes, France.,Centre de Lutte contre le Cancer Eugène Marquis, Rennes, France
| | - Alejandra Alvarez
- Department of Cell & Molecular Biology, Pontificia Universidad Católica de Chile, 8331010, Santiago, Chile
| | - Patricio Godoy
- IfADo-Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, 44139, Dortmund, Germany
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Alvaro Glavic
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile.,Center for Genome Regulation, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Guido Kroemer
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Inserm U1138, Université de Paris, Sorbonne Université, Paris, France.,Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France.,Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France.,Suzhou Institute for Systems Medicine, Chinese Academy of Medical Sciences, Suzhou, China.,Department of Women's and Children's Health, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden
| | - Claudio Hetz
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago, Chile. .,Center for Geroscience, Brain Health and Metabolism (GERO), Santiago, Chile. .,Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile. .,The Buck Institute for Research in Aging, Novato, CA, 94945, USA.
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17
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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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18
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Yan C, Liu J, Gao J, Sun Y, Zhang L, Song H, Xue L, Zhan L, Gao G, Ke Z, Liu Y, Liu J. IRE1 promotes neurodegeneration through autophagy-dependent neuron death in the Drosophila model of Parkinson's disease. Cell Death Dis 2019; 10:800. [PMID: 31641108 PMCID: PMC6805898 DOI: 10.1038/s41419-019-2039-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 08/19/2019] [Accepted: 10/01/2019] [Indexed: 01/05/2023]
Abstract
Abnormal aggregation of misfolded pathological proteins in neurons is a prominent feature of neurodegenerative disorders including Parkinson’s disease (PD). Perturbations of proteostasis at the endoplasmic reticulum (ER) triggers ER stress, activating the unfolded protein response (UPR). Chronic ER stress is thought to underlie the death of neurons during the neurodegenerative progression, but the precise mechanism by which the UPR pathways regulate neuronal cell fate remains incompletely understood. Here we report a critical neurodegenerative role for inositol-requiring enzyme 1 (IRE1), the evolutionarily conserved ER stress sensor, in a Drosophila model of PD. We found that IRE1 was hyperactivated upon accumulation of α-synuclein in the fly photoreceptor neurons. Ectopic overexpression of IRE1 was sufficient to trigger autophagy-dependent neuron death in an XBP1-independent, JNK-dependent manner. Furthermore, IRE1 was able to promote dopaminergic neuron loss, progressive locomotor impairment, and shorter lifespan, whereas blocking IRE1 or ATG7 expression remarkably ameliorated the progression of α-synuclein-caused Parkinson’s disease. These results provide in vivo evidence demonstrating that the IRE1 pathway drives PD progression through coupling ER stress to autophagy-dependent neuron death.
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Affiliation(s)
- Cheng Yan
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.,School of Medicine, Xinxiang University, Xinxiang, Henan, 453003, China
| | - Jingqi Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Jiamei Gao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Ying Sun
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Lei Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.,The State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Haiyun Song
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Lei Xue
- School of Life Science and Technology, Tongji University, Shanghai, 200092, China
| | - Lixing Zhan
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Guanjun Gao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Zunji Ke
- Department of Biochemistry, Basic Medical College, Shanghai University of Chinese Traditional Medicine, Shanghai, 201203, China
| | - Yong Liu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences; the Institute for Advanced Studies, Wuhan University, Wuhan, 430072, China.
| | - Jingnan Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China. .,School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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19
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Huang HW, Brown B, Chung J, Domingos PM, Ryoo HD. highroad Is a Carboxypetidase Induced by Retinoids to Clear Mutant Rhodopsin-1 in Drosophila Retinitis Pigmentosa Models. Cell Rep 2019; 22:1384-1391. [PMID: 29425495 PMCID: PMC5832065 DOI: 10.1016/j.celrep.2018.01.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 12/15/2017] [Accepted: 01/10/2018] [Indexed: 11/02/2022] Open
Abstract
Rhodopsins require retinoid chromophores for their function. In vertebrates, retinoids also serve as signaling molecules, but whether these molecules similarly regulate gene expression in Drosophila remains unclear. Here, we report the identification of a retinoid-inducible gene in Drosophila, highroad, which is required for photoreceptors to clear folding-defective mutant Rhodopsin-1 proteins. Specifically, knockdown or genetic deletion of highroad blocks the degradation of folding-defective Rhodopsin-1 mutant, ninaEG69D. Moreover, loss of highroad accelerates the age-related retinal degeneration phenotype of ninaEG69D mutants. Elevated highroad transcript levels are detected in ninaEG69D flies, and interestingly, deprivation of retinoids in the fly diet blocks this effect. Consistently, mutations in the retinoid transporter, santa maria, impairs the induction of highroad in ninaEG69D flies. In cultured S2 cells, highroad expression is induced by retinoic acid treatment. These results indicate that cellular quality-control mechanisms against misfolded Rhodopsin-1 involve regulation of gene expression by retinoids.
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Affiliation(s)
- Huai-Wei Huang
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA
| | - Brian Brown
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA
| | - Jaehoon Chung
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA
| | - Pedro M Domingos
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, Av. da República, Oeiras 2780-157, Portugal
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA.
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20
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Bae D, Moore KA, Mella JM, Hayashi SY, Hollien J. Degradation of Blos1 mRNA by IRE1 repositions lysosomes and protects cells from stress. J Cell Biol 2019; 218:1118-1127. [PMID: 30787040 PMCID: PMC6446841 DOI: 10.1083/jcb.201809027] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/28/2018] [Accepted: 01/23/2019] [Indexed: 11/22/2022] Open
Abstract
Bae et al. show that degradation of the mRNA encoding the adaptor Blos1 leads to the repositioning of late endosomes/lysosomes to the microtubule-organizing center in response to ER stress. This repositioning enhances cell survival during stress by promoting the clearance of protein aggregates. Cells respond to stress in the ER by initiating the widely conserved unfolded protein response. Activation of the ER transmembrane nuclease IRE1 leads to the degradation of specific mRNAs, but how this pathway affects the ability of cells to recover from stress is not known. Here, we show that degradation of the mRNA encoding biogenesis of lysosome-related organelles 1 subunit 1 (Blos1) leads to the repositioning of late endosomes (LEs)/lysosomes to the microtubule-organizing center in response to stress in mouse cells. Overriding Blos1 degradation led to ER stress sensitivity and the accumulation of ubiquitinated protein aggregates, whose efficient degradation required their independent trafficking to the cell center and the LE-associated endosomal sorting complexes required for transport. We propose that Blos1 regulation by IRE1 promotes LE-mediated microautophagy of protein aggregates and protects cells from their cytotoxic effects.
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Affiliation(s)
- Donghwi Bae
- School of Biological Sciences, University of Utah, Salt Lake City, UT
| | - Kristin A Moore
- School of Biological Sciences, University of Utah, Salt Lake City, UT
| | - Jessica M Mella
- School of Biological Sciences, University of Utah, Salt Lake City, UT
| | | | - Julie Hollien
- School of Biological Sciences, University of Utah, Salt Lake City, UT
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21
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Abstract
Eukaryotic cells respond to an overload of unfolded proteins in the endoplasmic reticulum (ER) by activating signaling pathways that are referred to as the unfolded protein response (UPR). Much UPR research has been conducted in cultured cells that exhibit no baseline UPR activity until they are challenged by ER stress initiated by chemicals or mutant proteins. At the same time, many genes that mediate UPR signaling are essential for the development of organisms ranging from Drosophila and fish to mice and humans, indicating that there is physiological ER stress that requires UPR in normally developing animal tissues. Recent studies have elucidated the tissue-specific roles of all three branches of UPR in distinct developing tissues of Drosophila, fish and mammals. As discussed in this Review, these studies not only reveal the physiological functions of the UPR pathways but also highlight a surprising degree of specificity associated with each UPR branch in development.
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Affiliation(s)
- Sahana Mitra
- Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, 540 First Avenue, New York, NY 10016, USA
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22
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Carew NT, Nelson AM, Liang Z, Smith SM, Milcarek C. Linking Endoplasmic Reticular Stress and Alternative Splicing. Int J Mol Sci 2018; 19:ijms19123919. [PMID: 30544499 PMCID: PMC6321306 DOI: 10.3390/ijms19123919] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 12/16/2022] Open
Abstract
RNA splicing patterns in antibody-secreting cells are shaped by endoplasmic reticulum stress, ELL2 (eleven-nineteen lysine-rich leukemia gene 2) induction, and changes in the levels of snRNAs. Endoplasmic reticulum stress induces the unfolded protein response comprising a highly conserved set of genes crucial for cell survival; among these is Ire1, whose auto-phosphorylation drives it to acquire a regulated mRNA decay activity. The mRNA-modifying function of phosphorylated Ire1 non-canonically splices Xbp1 mRNA and yet degrades other cellular mRNAs with related motifs. Naïve splenic B cells will activate Ire1 phosphorylation early on after lipopolysaccharide (LPS) stimulation, within 18 h; large-scale changes in mRNA content and splicing patterns result. Inhibition of the mRNA-degradation function of Ire1 is correlated with further differences in the splicing patterns and a reduction in the mRNA factors for snRNA transcription. Some of the >4000 splicing changes seen at 18 h after LPS stimulation persist into the late stages of antibody secretion, up to 72 h. Meanwhile some early splicing changes are supplanted by new splicing changes introduced by the up-regulation of ELL2, a transcription elongation factor. ELL2 is necessary for immunoglobulin secretion and does this by changing mRNA processing patterns of immunoglobulin heavy chain and >5000 other genes.
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Affiliation(s)
- Nolan T Carew
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Ashley M Nelson
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Zhitao Liang
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Sage M Smith
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
| | - Christine Milcarek
- School of Medicine, Department of Immunology, University of Pittsburgh, E1059 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
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Wong MY, DiChiara AS, Suen PH, Chen K, Doan ND, Shoulders MD. Adapting Secretory Proteostasis and Function Through the Unfolded Protein Response. Curr Top Microbiol Immunol 2018; 414:1-25. [PMID: 28929194 DOI: 10.1007/82_2017_56] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cells address challenges to protein folding in the secretory pathway by engaging endoplasmic reticulum (ER)-localized protective mechanisms that are collectively termed the unfolded protein response (UPR). By the action of the transmembrane signal transducers IRE1, PERK, and ATF6, the UPR induces networks of genes whose products alleviate the burden of protein misfolding. The UPR also plays instructive roles in cell differentiation and development, aids in the response to pathogens, and coordinates the output of professional secretory cells. These functions add to and move beyond the UPR's classical role in addressing proteotoxic stress. Thus, the UPR is not just a reaction to protein misfolding, but also a fundamental driving force in physiology and pathology. Recent efforts have yielded a suite of chemical genetic methods and small molecule modulators that now provide researchers with both stress-dependent and -independent control of UPR activity. Such tools provide new opportunities to perturb the UPR and thereby study mechanisms for maintaining proteostasis in the secretory pathway. Numerous observations now hint at the therapeutic potential of UPR modulation for diseases related to the misfolding and aggregation of ER client proteins. Growing evidence also indicates the promise of targeting ER proteostasis nodes downstream of the UPR. Here, we review selected advances in these areas, providing a resource to inform ongoing studies of secretory proteostasis and function as they relate to the UPR.
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Affiliation(s)
- Madeline Y Wong
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Andrew S DiChiara
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Patreece H Suen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Kenny Chen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Ngoc-Duc Doan
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA
| | - Matthew D Shoulders
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139-4307, USA.
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24
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Van Den Brink DM, Cubizolle A, Chatelain G, Davoust N, Girard V, Johansen S, Napoletano F, Dourlen P, Guillou L, Angebault-Prouteau C, Bernoud-Hubac N, Guichardant M, Brabet P, Mollereau B. Physiological and pathological roles of FATP-mediated lipid droplets in Drosophila and mice retina. PLoS Genet 2018; 14:e1007627. [PMID: 30199545 PMCID: PMC6147681 DOI: 10.1371/journal.pgen.1007627] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 09/20/2018] [Accepted: 08/13/2018] [Indexed: 11/18/2022] Open
Abstract
Increasing evidence suggests that dysregulation of lipid metabolism is associated with neurodegeneration in retinal diseases such as age-related macular degeneration and in brain disorders such as Alzheimer’s and Parkinson’s diseases. Lipid storage organelles (lipid droplets, LDs), accumulate in many cell types in response to stress, and it is now clear that LDs function not only as lipid stores but also as dynamic regulators of the stress response. However, whether these LDs are always protective or can also be deleterious to the cell is unknown. Here, we investigated the consequences of LD accumulation on retinal cell homeostasis under physiological and stress conditions in Drosophila and in mice. In wild-type Drosophila, we show that dFatp is required and sufficient for expansion of LD size in retinal pigment cells (RPCs) and that LDs in RPCs are required for photoreceptor survival during aging. Similarly, in mice, LD accumulation induced by RPC-specific expression of human FATP1 was non-toxic and promoted mitochondrial energy metabolism in RPCs and non-autonomously in photoreceptor cells. In contrast, the inhibition of LD accumulation by dFatp knockdown suppressed neurodegeneration in Aats-metFBDrosophila mutants, which carry elevated levels of reactive oxygen species (ROS). This suggests that abnormal turnover of LD may be toxic for photoreceptors cells of the retina under oxidative stress. Collectively, these findings indicate that FATP-mediated LD formation in RPCs promotes RPC and neuronal homeostasis under physiological conditions but could be deleterious for the photoreceptors under pathological conditions. Lipids are major cell constituents and are present in the membranes, as free lipids in the cytoplasm, or stored in vesicles called lipid droplets (LDs). Under conditions of stress, lipids stored in LDs can be released to serve as substrates for energy metabolism by mitochondria. However, lipid storage is dysregulated in many degenerative disorders such as age-related macular degeneration, Parkinson’s and Alzheimer’s diseases. Thus, it is unclear whether accumulation of LDs is protective or toxic for neuronal cells. To address this question, we examined the consequences of removal or enforced LD accumulation on the health of retinal cells in flies and mice. Like humans, fly and mouse retinas contain retinal pigment cells (RPC) that support the functions of neighboring photoreceptor cells. We found that overexpression of the fatty acid transport protein (FATP) in RPCs induced accumulation of LDs in both transgenic flies and mice. Moreover, LD accumulation in RPCs was not harmful for juxtaposed photoreceptors during aging, but was toxic under stress conditions. We propose that lipid storage promotes cellular communication that affects photoreceptor health.
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Affiliation(s)
- Daan M. Van Den Brink
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Aurélie Cubizolle
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- Université de Montpellier, Montpellier, France
| | - Gilles Chatelain
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Nathalie Davoust
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Victor Girard
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Simone Johansen
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Francesco Napoletano
- Molecular Oncology Unit, Department of Life Sciences, University of Trieste c/o Laboratorio Nazionale CIB, Area Science Park, Trieste, Italy
| | - Pierre Dourlen
- Institut Pasteur de Lille; Inserm, U1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases; University Lille, U1167-Excellence Laboratory LabEx DISTALZ, Lille, France
| | - Laurent Guillou
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- Université de Montpellier, Montpellier, France
| | - Claire Angebault-Prouteau
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- INSERM U1046, UMR CNRS 9214, Université de Montpellier, CHRU de Montpellier, Montpellier, France
| | - Nathalie Bernoud-Hubac
- Univ Lyon, CarMeN laboratory, INSA Lyon, INSERM U1060, INRA U1397, Université Claude Bernard Lyon 1, F-69621, Villeurbanne, France
| | - Michel Guichardant
- Univ Lyon, CarMeN laboratory, INSA Lyon, INSERM U1060, INRA U1397, Université Claude Bernard Lyon 1, F-69621, Villeurbanne, France
| | - Philippe Brabet
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- Université de Montpellier, Montpellier, France
| | - Bertrand Mollereau
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
- * E-mail:
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25
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Unfolding the Endoplasmic Reticulum of a Social Amoeba: Dictyostelium discoideum as a New Model for the Study of Endoplasmic Reticulum Stress. Cells 2018; 7:cells7060056. [PMID: 29890774 PMCID: PMC6025073 DOI: 10.3390/cells7060056] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 05/28/2018] [Accepted: 06/05/2018] [Indexed: 01/19/2023] Open
Abstract
The endoplasmic reticulum (ER) is a membranous network with an intricate dynamic architecture necessary for various essential cellular processes. Nearly one third of the proteins trafficking through the secretory pathway are folded and matured in the ER. Additionally, it acts as calcium storage, and it is a main source for lipid biosynthesis. The ER is highly connected with other organelles through regions of membrane apposition that allow organelle remodeling, as well as lipid and calcium traffic. Cells are under constant changes due to metabolic requirements and environmental conditions that challenge the ER network’s maintenance. The unfolded protein response (UPR) is a signaling pathway that restores homeostasis of this intracellular compartment upon ER stress conditions by reducing the load of proteins, and by increasing the processes of protein folding and degradation. Significant progress on the study of the mechanisms that restore ER homeostasis was achieved using model organisms such as yeast, Arabidopsis, and mammalian cells. In this review, we address the current knowledge on ER architecture and ER stress response in Dictyostelium discoideum. This social amoeba alternates between unicellular and multicellular phases and is recognized as a valuable biomedical model organism and an alternative to yeast, particularly for the presence of traits conserved in animal cells that were lost in fungi.
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26
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Adrain C, Henis-Korenblit S, Domingos PM. Meeting Report - proteostasis in Ericeira. J Cell Sci 2018; 131:131/5/jcs216150. [PMID: 29496898 DOI: 10.1242/jcs.216150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
It was a sunny Ericeira, in Portugal, that received the participants of the EMBO Workshop on Proteostasis, from 17 to 21 November 2017. Most participants gave talks or presented posters concerning their most recent research results, and lively scientific discussions occurred against the backdrop of the beautiful Atlantic Ocean.Proteostasis is the portmanteau of the words protein and homeostasis, and it refers to the biological mechanisms controlling the biogenesis, folding, trafficking and degradation of proteins in cells. An imbalance in proteostasis can lead to the accumulation of misfolded proteins or excessive protein degradation, and is associated with many human diseases. A wide variety of research approaches are used to identify the mechanisms that regulate proteostasis, typically involving different model organisms (yeast, invertebrates or mammalian systems) and different methodologies (genetics, biochemistry, biophysics, structural biology, cell biology and organismal biology). Around 140 researchers in the proteostasis field met in the Hotel Vila Galé, Ericeira, Portugal for the EMBO Workshop in Proteostasis, organized by Pedro Domingos (ITQB-NOVA, Oeiras, Portugal) and Colin Adrain (IGC, Oeiras, Portugal). In this report, we attempt to review and integrate the ideas that emerged at the workshop. Owing to space restrictions, we could not cover all talks or posters and we apologize to the colleagues whose presentations could not be discussed.
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Affiliation(s)
- Colin Adrain
- Membrane Traffic Lab, Instituto Gulbenkian de Ciência (IGC), Oeiras, Portugal
| | - Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Pedro M Domingos
- Instituto de Tecnologia Química e Biológica (ITQB-NOVA), Oeiras, Portugal
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27
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Sepulveda D, Rojas-Rivera D, Rodríguez DA, Groenendyk J, Köhler A, Lebeaupin C, Ito S, Urra H, Carreras-Sureda A, Hazari Y, Vasseur-Cognet M, Ali MMU, Chevet E, Campos G, Godoy P, Vaisar T, Bailly-Maitre B, Nagata K, Michalak M, Sierralta J, Hetz C. Interactome Screening Identifies the ER Luminal Chaperone Hsp47 as a Regulator of the Unfolded Protein Response Transducer IRE1α. Mol Cell 2018; 69:238-252.e7. [PMID: 29351844 DOI: 10.1016/j.molcel.2017.12.028] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 10/05/2017] [Accepted: 12/27/2017] [Indexed: 01/17/2023]
Abstract
Maintenance of endoplasmic reticulum (ER) proteostasis is controlled by a dynamic signaling network known as the unfolded protein response (UPR). IRE1α is a major UPR transducer, determining cell fate under ER stress. We used an interactome screening to unveil several regulators of the UPR, highlighting the ER chaperone Hsp47 as the major hit. Cellular and biochemical analysis indicated that Hsp47 instigates IRE1α signaling through a physical interaction. Hsp47 directly binds to the ER luminal domain of IRE1α with high affinity, displacing the negative regulator BiP from the complex to facilitate IRE1α oligomerization. The regulation of IRE1α signaling by Hsp47 is evolutionarily conserved as validated using fly and mouse models of ER stress. Hsp47 deficiency sensitized cells and animals to experimental ER stress, revealing the significance of Hsp47 to global proteostasis maintenance. We conclude that Hsp47 adjusts IRE1α signaling by fine-tuning the threshold to engage an adaptive UPR.
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Affiliation(s)
- Denisse Sepulveda
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | - Diego Rojas-Rivera
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | - Diego A Rodríguez
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile; Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jody Groenendyk
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
| | - Andres Köhler
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Program of Physiology and Biophysics, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | | | - Shinya Ito
- Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto and Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Hery Urra
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | - Amado Carreras-Sureda
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | - Younis Hazari
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | - Mireille Vasseur-Cognet
- Institut d'Ecologie et des Sciences de l'Environnement de Paris, Bondy; Sorbonne Universités, and Institut National de la Santé et de la Recherche Médicale, Paris 7 113, France
| | - Maruf M U Ali
- Department of Life Sciences, Imperial College, London SW7 2AZ, UK
| | - Eric Chevet
- Inserm U1242, Chemistry, Oncogenesis, Stress, & Signaling, University of Rennes 1, F-35000 Rennes, France; Centre de Lutte le Cancer Eugène Marquis, F-35000 Rennes, France
| | - Gisela Campos
- IfADo-Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund 44139, Germany
| | - Patricio Godoy
- IfADo-Leibniz Research Centre for Working Environment and Human Factors at the Technical University Dortmund, Dortmund 44139, Germany
| | - Tomas Vaisar
- Division of Metabolism, Endocrinology and Nutrition, University of Washington School of Medicine, Seattle, WA 98195, USA
| | | | - Kazuhiro Nagata
- Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto and Sangyo University, Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555, Japan
| | - Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2S7, Canada
| | - Jimena Sierralta
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Program of Physiology and Biophysics, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, University of Chile, Santiago 8380453, Chile; Center for Geroscience, Brain Health, and Metabolism (GERO), Santiago, Chile; Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, University of Chile, Santiago 8380453, Chile; Buck Institute for Research on Aging, Novato, CA 94945, USA; Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston MA 02115, USA.
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28
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Luis NM, Wang L, Ortega M, Deng H, Katewa SD, Li PWL, Karpac J, Jasper H, Kapahi P. Intestinal IRE1 Is Required for Increased Triglyceride Metabolism and Longer Lifespan under Dietary Restriction. Cell Rep 2017; 17:1207-1216. [PMID: 27783936 DOI: 10.1016/j.celrep.2016.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 05/18/2016] [Accepted: 09/30/2016] [Indexed: 12/12/2022] Open
Abstract
Dietary restriction (DR) is one of the most robust lifespan-extending interventions in animals. The beneficial effects of DR involve a metabolic adaptation toward increased triglyceride usage. The regulatory mechanism and the tissue specificity of this metabolic switch remain unclear. Here, we show that the IRE1/XBP1 endoplasmic reticulum (ER) stress signaling module mediates metabolic adaptation upon DR in flies by promoting triglyceride synthesis and accumulation in enterocytes (ECs) of the Drosophila midgut. Consistently, IRE1/XBP1 function in ECs is required for increased longevity upon DR. We further identify sugarbabe, a Gli-like zinc-finger transcription factor, as a key mediator of the IRE1/XBP1-regulated induction of de novo lipogenesis in ECs. Overexpression of sugarbabe rescues metabolic and lifespan phenotypes of IRE1 loss-of-function conditions. Our study highlights the critical role of metabolic adaptation of the intestinal epithelium for DR-induced lifespan extension and explores the IRE1/XBP1 signaling pathway regulating this adaptation and influencing lifespan.
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Affiliation(s)
- Nuno Miguel Luis
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA.
| | - Lifen Wang
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Mauricio Ortega
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Hansong Deng
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Subhash D Katewa
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Patrick Wai-Lun Li
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA
| | - Jason Karpac
- Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843, USA
| | - Heinrich Jasper
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA; Leibniz Institute on Aging - Fritz Lipmann Institute (FLI), Jena 07745, Germany.
| | - Pankaj Kapahi
- Buck Institute for Research on Aging, 8001 Redwood Boulevard, Novato, CA 94945-1400, USA.
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29
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Abstract
Tango1 enables ER-to-Golgi trafficking of large proteins. We show here that loss of Tango1, in addition to disrupting protein secretion and ER/Golgi morphology, causes ER stress and defects in cell shape. We find that the previously observed dependence of smaller cargos on Tango1 is a secondary effect. If large cargos like Dumpy, which we identify as a Tango1 cargo, are removed from the cell, nonbulky proteins reenter the secretory pathway. Removal of blocking cargo also restores cell morphology and attenuates the ER-stress response. Thus, failures in the secretion of nonbulky proteins, ER stress, and defective cell morphology are secondary consequences of bulky cargo retention. By contrast, ER/Golgi defects in Tango1-depleted cells persist in the absence of bulky cargo, showing that they are due to a secretion-independent function of Tango1. Therefore, maintenance of ER/Golgi architecture and bulky cargo transport are the primary functions for Tango1.
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30
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Ishikawa T, Kashima M, Nagano AJ, Ishikawa-Fujiwara T, Kamei Y, Todo T, Mori K. Unfolded protein response transducer IRE1-mediated signaling independent of XBP1 mRNA splicing is not required for growth and development of medaka fish. eLife 2017; 6:26845. [PMID: 28952924 PMCID: PMC5636610 DOI: 10.7554/elife.26845] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 09/25/2017] [Indexed: 12/14/2022] Open
Abstract
When activated by the accumulation of unfolded proteins in the endoplasmic reticulum, metazoan IRE1, the most evolutionarily conserved unfolded protein response (UPR) transducer, initiates unconventional splicing of XBP1 mRNA. Unspliced and spliced mRNA are translated to produce pXBP1(U) and pXBP1(S), respectively. pXBP1(S) functions as a potent transcription factor, whereas pXBP1(U) targets pXBP1(S) to degradation. In addition, activated IRE1 transmits two signaling outputs independent of XBP1, namely activation of the JNK pathway, which is initiated by binding of the adaptor TRAF2 to phosphorylated IRE1, and regulated IRE1-dependent decay (RIDD) of various mRNAs in a relatively nonspecific manner. Here, we conducted comprehensive and systematic genetic analyses of the IRE1-XBP1 branch of the UPR using medaka fish and found that the defects observed in XBP1-knockout or IRE1-knockout medaka were fully rescued by constitutive expression of pXBP1(S). Thus, the JNK and RIDD pathways are not required for the normal growth and development of medaka. The unfolded protein response sensor/transducer IRE1-mediated splicing of XBP1 mRNA encoding its active downstream transcription factor to maintain the homeostasis of the endoplasmic reticulum is sufficient for growth and development of medaka fish.
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Affiliation(s)
- Tokiro Ishikawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Makoto Kashima
- Research Institute for Food and Agriculture, Ryukoku University, Otsu, Japan
| | | | | | - Yasuhiro Kamei
- Spectrography and Bioimaging Facility, National Institute for Basic Biology, Okazaki, Japan
| | - Takeshi Todo
- Graduate School of Medicine, Osaka University, Suita, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
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31
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Huang HW, Zeng X, Rhim T, Ron D, Ryoo HD. The requirement of IRE1 and XBP1 in resolving physiological stress during Drosophila development. J Cell Sci 2017; 130:3040-3049. [PMID: 28775151 PMCID: PMC5612175 DOI: 10.1242/jcs.203612] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 07/31/2017] [Indexed: 01/11/2023] Open
Abstract
IRE1 mediates the unfolded protein response (UPR) in part by regulating XBP1 mRNA splicing in response to endoplasmic reticulum (ER) stress. In cultured metazoan cells, IRE1 also exhibits XBP1-independent biochemical activities. IRE1 and XBP1 are developmentally essential genes in Drosophila and mammals, but the source of the physiological ER stress and the relative contributions of XBP1 activation versus other IRE1 functions to development remain unknown. Here, we employed Drosophila to address this question. Explicitly, we find that specific regions of the developing alimentary canal, fat body and the male reproductive organ are the sources of physiological stress that require Ire1 and Xbp1 for resolution. In particular, the developmental lethality associated with an Xbp1 null mutation was rescued by transgenic expression of Xbp1 in the alimentary canal. The domains of IRE1 that are involved in detecting unfolded proteins, cleaving RNAs and activating XBP1 splicing were all essential for development. The earlier onset of developmental defects in Ire1 mutant larvae compared to in Xbp1-null flies supports a developmental role for XBP1-independent IRE1 RNase activity, while challenging the importance of RNase-independent effector mechanisms of Drosophila IRE1 function.
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Affiliation(s)
- Huai-Wei Huang
- Department of Cell Biology, New York University School of Medicine, New York 10016, USA
| | - Xiaomei Zeng
- Key Laboratory of Molecular Biophysics of Ministry of Education, Center for Human Genome Research, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430000, China
| | - Taiyoun Rhim
- Department of Bioengineering, Hanyang University, Seoul 04763, Korea
| | - David Ron
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, Cambridge CB2 0XY, UK
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York 10016, USA
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Jung WH, Liu CC, Yu YL, Chang YC, Lien WY, Chao HC, Huang SY, Kuo CH, Ho HC, Chan CC. Lipophagy prevents activity-dependent neurodegeneration due to dihydroceramide accumulation in vivo. EMBO Rep 2017; 18:1150-1165. [PMID: 28507162 DOI: 10.15252/embr.201643480] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 03/30/2017] [Accepted: 04/06/2017] [Indexed: 12/18/2022] Open
Abstract
Dihydroceramide desaturases are evolutionarily conserved enzymes that convert dihydroceramide (dhCer) to ceramide (Cer). While elevated Cer levels cause neurodegenerative diseases, the neuronal activity of its direct precursor, dhCer, remains unclear. We show that knockout of the fly dhCer desaturase gene, infertile crescent (ifc), results in larval lethality with increased dhCer and decreased Cer levels. Light stimulation leads to ROS increase and apoptotic cell death in ifc-KO photoreceptors, resulting in activity-dependent neurodegeneration. Lipid-containing Atg8/LC3-positive puncta accumulate in ifc-KO photoreceptors, suggesting lipophagy activation. Further enhancing lipophagy reduces lipid droplet accumulation and rescues ifc-KO defects, indicating that lipophagy plays a protective role. Reducing dhCer synthesis prevents photoreceptor degeneration and rescues ifc-KO lethality, while supplementing downstream sphingolipids does not. These results pinpoint that dhCer accumulation is responsible for ifc-KO defects. Human dhCer desaturase rescues ifc-KO larval lethality, and rapamycin reverses defects caused by dhCer accumulation in human neuroblastoma cells, suggesting evolutionarily conserved functions. This study demonstrates a novel requirement for dhCer desaturase in neuronal maintenance in vivo and shows that lipophagy activation prevents activity-dependent degeneration caused by dhCer accumulation.
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Affiliation(s)
- Wei-Hung Jung
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chung-Chih Liu
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Lian Yu
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Chin Chang
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Yu Lien
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Hsi-Chun Chao
- School of Pharmacy, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Yi Huang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Ching-Hua Kuo
- School of Pharmacy, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Han-Chen Ho
- Department of Anatomy, Tzu-Chi University, Hualien, Taiwan
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Salzberg Y, Coleman AJ, Celestrin K, Cohen-Berkman M, Biederer T, Henis-Korenblit S, Bülow HE. Reduced Insulin/Insulin-Like Growth Factor Receptor Signaling Mitigates Defective Dendrite Morphogenesis in Mutants of the ER Stress Sensor IRE-1. PLoS Genet 2017; 13:e1006579. [PMID: 28114319 PMCID: PMC5293268 DOI: 10.1371/journal.pgen.1006579] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 02/06/2017] [Accepted: 01/11/2017] [Indexed: 11/18/2022] Open
Abstract
Neurons receive excitatory or sensory inputs through their dendrites, which often branch extensively to form unique neuron-specific structures. How neurons regulate the formation of their particular arbor is only partially understood. In genetic screens using the multidendritic arbor of PVD somatosensory neurons in the nematode Caenorhabditis elegans, we identified a mutation in the ER stress sensor IRE-1/Ire1 (inositol requiring enzyme 1) as crucial for proper PVD dendrite arborization in vivo. We further found that regulation of dendrite growth in cultured rat hippocampal neurons depends on Ire1 function, showing an evolutionarily conserved role for IRE-1/Ire1 in dendrite patterning. PVD neurons of nematodes lacking ire-1 display reduced arbor complexity, whereas mutations in genes encoding other ER stress sensors displayed normal PVD dendrites, specifying IRE-1 as a selective ER stress sensor that is essential for PVD dendrite morphogenesis. Although structure function analyses indicated that IRE-1's nuclease activity is necessary for its role in dendrite morphogenesis, mutations in xbp-1, the best-known target of non-canonical splicing by IRE-1/Ire1, do not exhibit PVD phenotypes. We further determined that secretion and distal localization to dendrites of the DMA-1/leucine rich transmembrane receptor (DMA-1/LRR-TM) is defective in ire-1 but not xbp-1 mutants, suggesting a block in the secretory pathway. Interestingly, reducing Insulin/IGF1 signaling can bypass the secretory block and restore normal targeting of DMA-1, and consequently normal PVD arborization even in the complete absence of functional IRE-1. This bypass of ire-1 requires the DAF-16/FOXO transcription factor. In sum, our work identifies a conserved role for ire-1 in neuronal branching, which is independent of xbp-1, and suggests that arborization defects associated with neuronal pathologies may be overcome by reducing Insulin/IGF signaling and improving ER homeostasis and function.
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Affiliation(s)
- Yehuda Salzberg
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Andrew J. Coleman
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States of America
| | - Kevin Celestrin
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Moran Cohen-Berkman
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Thomas Biederer
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States of America
| | - Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Hannes E. Bülow
- Department of Genetics, Albert Einstein College of Medicine, Bronx, New York, United States of America
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, United States of America
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Unique roles of the unfolded protein response pathway in fungal development and differentiation. Sci Rep 2016; 6:33413. [PMID: 27629591 PMCID: PMC5024300 DOI: 10.1038/srep33413] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/11/2016] [Indexed: 01/05/2023] Open
Abstract
Cryptococcus neoformans, a global fungal meningitis pathogen, employs the unfolded protein response pathway. This pathway, which consists of an evolutionarily conserved Ire1 kinase/endoribonuclease and a unique transcription factor (Hxl1), modulates the endoplasmic reticulum stress response and pathogenicity. Here, we report that the unfolded protein response pathway governs sexual and unisexual differentiation of C. neoformans in an Ire1-dependent but Hxl1-independent manner. The ire1∆ mutants showed defects in sexual mating, with reduced cell fusion and pheromone-mediated formation of the conjugation tube. Unexpectedly, these mating defects did not result from defective pheromone production because expression of the mating pheromone gene (MFα1) was strongly induced in the ire1∆ mutant. Ire1 controls sexual differentiation by modulating the function of the molecular chaperone Kar2 and by regulating mating-induced localisation of mating pheromone transporter (Ste6) and receptor (Ste3/Cprα). Deletion of IRE1, but not HXL1, also caused significant defects in unisexual differentiation in a Kar2-independent manner. Moreover, we showed that Rim101 is a novel downstream factor of Ire1 for production of the capsule, which is a unique structural determinant of C. neoformans virulence. Therefore, Ire1 uniquely regulates fungal development and differentiation in an Hxl1-independent manner.
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Abstract
Endoplasmic Reticulum (ER) is an organelle where most secretory and membrane proteins are synthesized, folded, and undergo further maturation. As numerous conditions can perturb such ER function, eukaryotic cells are equipped with responsive signaling pathways, widely referred to as the Unfolded Protein Response (UPR). Chronic conditions of ER stress that cannot be fully resolved by UPR, or conditions that impair UPR signaling itself, are associated with many metabolic and degenerative diseases. In recent years, Drosophila has been actively employed to study such connections between UPR and disease. Notably, the UPR pathways are largely conserved between Drosophila and humans, and the mediating genes are essential for development in both organisms, indicating their requirement to resolve inherent stress. By now, many Drosophila mutations are known to impose stress in the ER, and a number of these appear similar to those that underlie human diseases. In addition, studies have employed the strategy of overexpressing human mutations in Drosophila tissues to perform genetic modifier screens. The fact that the basic UPR pathways are conserved, together with the availability of many human disease models in this organism, makes Drosophila a powerful tool for studying human disease mechanisms. [BMB Reports 2015; 48(8): 445-453]
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Affiliation(s)
- Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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Wang M, Kaufman RJ. Protein misfolding in the endoplasmic reticulum as a conduit to human disease. Nature 2016; 529:326-35. [PMID: 26791723 DOI: 10.1038/nature17041] [Citation(s) in RCA: 1053] [Impact Index Per Article: 131.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/11/2015] [Indexed: 12/18/2022]
Abstract
In eukaryotic cells, the endoplasmic reticulum is essential for the folding and trafficking of proteins that enter the secretory pathway. Environmental insults or increased protein synthesis often lead to protein misfolding in the organelle, the accumulation of misfolded or unfolded proteins - known as endoplasmic reticulum stress - and the activation of the adaptive unfolded protein response to restore homeostasis. If protein misfolding is not resolved, cells die. Endoplasmic reticulum stress and activation of the unfolded protein response help to determine cell fate and function. Furthermore, endoplasmic reticulum stress contributes to the aetiology of many human diseases.
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Affiliation(s)
- Miao Wang
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
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Godin JD, Creppe C, Laguesse S, Nguyen L. Emerging Roles for the Unfolded Protein Response in the Developing Nervous System. Trends Neurosci 2016; 39:394-404. [PMID: 27130659 DOI: 10.1016/j.tins.2016.04.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/23/2016] [Accepted: 04/04/2016] [Indexed: 01/04/2023]
Abstract
The unfolded protein response (UPR) is a homeostatic signaling pathway triggered by protein misfolding in the endoplasmic reticulum (ER). Beyond its protective role, it plays important functions during normal development in response to elevated demand for protein folding. Several UPR effectors show dynamic temporal and spatial expression patterns that correlate with milestones of the central nervous system (CNS) development. Here, we discuss recent studies suggesting that a dynamic regulation of UPR supports generation, maturation, and maintenance of differentiated neurons in the CNS. We further highlight studies supporting a developmental vulnerability of CNS to UPR dysregulation, which underlies neurodevelopmental disorders. We believe that a better understanding of UPR functions may provide novel opportunities for therapeutic strategies to fight ER/UPR-associated human neurological disorders.
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Affiliation(s)
- Juliette D Godin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, Illkirch, France.
| | - Catherine Creppe
- GIGA-Neurosciences, University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium
| | - Sophie Laguesse
- GIGA-Neurosciences, University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium
| | - Laurent Nguyen
- GIGA-Neurosciences, University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Interdisciplinary Cluster for Applied Genoproteomics (GIGA-R), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium; Walloon Excellence in Lifesciences and Biotechnology (WELBIO), University of Liège, C.H.U. Sart Tilman, Liège 4000, Belgium.
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Xu Z, Chikka MR, Xia H, Ready DF. Ire1 supports normal ER differentiation in developing Drosophila photoreceptors. J Cell Sci 2016; 129:921-9. [PMID: 26787744 PMCID: PMC4813318 DOI: 10.1242/jcs.180406] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 01/12/2016] [Indexed: 01/09/2023] Open
Abstract
The endoplasmic reticulum (ER) serves virtually all aspects of cell physiology and, by pathways that are incompletely understood, is dynamically remodeled to meet changing cell needs. Inositol-requiring enzyme 1 (Ire1), a conserved core protein of the unfolded protein response (UPR), participates in ER remodeling and is particularly required during the differentiation of cells devoted to intense secretory activity, so-called 'professional' secretory cells. Here, we characterize the role of Ire1 in ER differentiation in the developing Drosophila compound eye photoreceptors (R cells). As part of normal development, R cells take a turn as professional secretory cells with a massive secretory effort that builds the photosensitive membrane organelle, the rhabdomere. We find rough ER sheets proliferate as rhabdomere biogenesis culminates, and Ire1 is required for normal ER differentiation. Ire1 is active early in R cell development and is required in anticipation of peak biosynthesis. Without Ire1, the amount of rough ER sheets is strongly reduced and the extensive cortical ER network at the rhabdomere base, the subrhabdomere cisterna (SRC), fails. Instead, ER proliferates in persistent and ribosome-poor tubular tangles. A phase of Ire1 activity early in R cell development thus shapes dynamic ER.
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Affiliation(s)
- Zuyuan Xu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | | - Hongai Xia
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Donald F Ready
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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Dandekar A, Mendez R, Zhang K. Cross talk between ER stress, oxidative stress, and inflammation in health and disease. Methods Mol Biol 2015; 1292:205-14. [PMID: 25804758 DOI: 10.1007/978-1-4939-2522-3_15] [Citation(s) in RCA: 264] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In mammals, endoplasmic reticulum (ER) stress, oxidative stress, and inflammatory responses compose the major defense networks that help the cells adapt to and survive stress conditions caused by biochemical, physiological and pathological stimuli. However, chronic ER stress, oxidative stress, or inflammation have been found to be associated with the initiation and progression of a variety of human diseases in the modern world. Under many pathophysiologic conditions, ER stress response, oxidative stress, and inflammatory responses are integrated and amplified in specialized cell types to facilitate the progression of disease. In the past few decades, ER stress response, oxidative stress, and inflammation as well as their interactive relationships have been hot research topics in biomedicine. In this review, we summarize the recent advance in our understanding of the cross talk between ER stress response, oxidative stress, and inflammation in immunity and in inflammatory and metabolic diseases.
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Affiliation(s)
- Aditya Dandekar
- Department of Immunology and Microbiology, Karmanos Cancer Institute, Wayne State University School of Medicine, 3202 Scott Hall, 540 East Canfield, Detroit, MI, 48201, USA
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Fatty acid transport proteins in disease: New insights from invertebrate models. Prog Lipid Res 2015; 60:30-40. [PMID: 26416577 DOI: 10.1016/j.plipres.2015.08.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 08/18/2015] [Indexed: 11/22/2022]
Abstract
The dysregulation of lipid metabolism has been implicated in various diseases, including diabetes, cardiopathies, dermopathies, retinal and neurodegenerative diseases. Mouse models have provided insights into lipid metabolism. However, progress in the understanding of these pathologies is hampered by the multiplicity of essential cellular processes and genes that modulate lipid metabolism. Drosophila and Caenorhabditis elegans have emerged as simple genetic models to improve our understanding of these metabolic diseases. Recent studies have characterized fatty acid transport protein (fatp) mutants in Drosophila and C. elegans, establishing new models of cardiomyopathy, retinal degeneration, fat storage disease and dermopathies. These models have generated novel insights into the physiological role of the Fatp protein family in vivo in multicellular organisms, and are likely to contribute substantially to progress in understanding the etiology of various metabolic disorders. Here, we describe and discuss the mechanisms underlying invertebrate fatp mutant models in the light of the current knowledge relating to FATPs and lipid disorders in vertebrates.
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Moore K, Hollien J. Ire1-mediated decay in mammalian cells relies on mRNA sequence, structure, and translational status. Mol Biol Cell 2015; 26:2873-84. [PMID: 26108623 PMCID: PMC4571326 DOI: 10.1091/mbc.e15-02-0074] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 06/16/2015] [Indexed: 12/16/2022] Open
Abstract
Endoplasmic reticulum (ER) stress induces the degradation of mRNAs by Ire1. In mammalian cells, this process depends on specific stem-loop structures in the target mRNAs and on Perk, a second sensor of ER stress. Perk appears to be required to translationally attenuate the stem-loop regions of target mRNAs. Endoplasmic reticulum (ER) stress occurs when misfolded proteins overwhelm the capacity of the ER, resulting in activation of the unfolded protein response (UPR). Ire1, an ER transmembrane nuclease and conserved transducer of the UPR, cleaves the mRNA encoding the transcription factor Xbp1 at a dual stem-loop (SL) structure, leading to Xbp1 splicing and activation. Ire1 also cleaves other mRNAs localized to the ER membrane through regulated Ire1-dependent decay (RIDD). We find that during acute ER stress in mammalian cells, Xbp1-like SLs within the target mRNAs are necessary for RIDD. Furthermore, depletion of Perk, a UPR transducer that attenuates translation during ER stress, inhibits RIDD in a substrate-specific manner. Artificially blocking translation of the SL region of target mRNAs fully restores RIDD in cells depleted of Perk, suggesting that ribosomes disrupt SL formation and/or Ire1 binding. This coordination between Perk and Ire1 may serve to spatially and temporally regulate RIDD.
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Affiliation(s)
- Kristin Moore
- Department of Biology and Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
| | - Julie Hollien
- Department of Biology and Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112
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Wei X, Howell AS, Dong X, Taylor CA, Cooper RC, Zhang J, Zou W, Sherwood DR, Shen K. The unfolded protein response is required for dendrite morphogenesis. eLife 2015; 4:e06963. [PMID: 26052671 PMCID: PMC4484204 DOI: 10.7554/elife.06963] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 06/07/2015] [Indexed: 11/13/2022] Open
Abstract
Precise patterning of dendritic fields is essential for the formation and function of neuronal circuits. During development, dendrites acquire their morphology by exuberant branching. How neurons cope with the increased load of protein production required for this rapid growth is poorly understood. Here we show that the physiological unfolded protein response (UPR) is induced in the highly branched Caenorhabditis elegans sensory neuron PVD during dendrite morphogenesis. Perturbation of the IRE1 arm of the UPR pathway causes loss of dendritic branches, a phenotype that can be rescued by overexpression of the ER chaperone HSP-4 (a homolog of mammalian BiP/ grp78). Surprisingly, a single transmembrane leucine-rich repeat protein, DMA-1, plays a major role in the induction of the UPR and the dendritic phenotype in the UPR mutants. These findings reveal a significant role for the physiological UPR in the maintenance of ER homeostasis during morphogenesis of large dendritic arbors. DOI:http://dx.doi.org/10.7554/eLife.06963.001 The brain consists of billions of cells called neurons that can rapidly send and receive information. At one end of the neuron, branched structures called dendrites receive signals from other cells. The number of dendrites and the amount of branching vary in different types of neurons. These patterns are crucial for each neuron to receive the information it needs. Abnormalities in dendrites affect brain activity and are associated with several diseases in humans. To make dendrites, the neuron needs to increase the amount of protein and other cell materials it produces. New proteins are made in a compartment called the endoplasmic reticulum and are folded into particular three-dimensional shapes with the help of chaperone proteins. These chaperones may be overwhelmed if protein production increases, leading to some proteins being folded incorrectly. This can activate a system called the unfolded protein response, which increases the number of chaperone proteins so that the proteins can be refolded correctly. However, it was not clear if neurons rely on the unfolded protein response, or another system, to cope with the increased levels of protein production needed to form complicated dendrite structures. Wei et al. studied a type of neuron called PVD—which has an elaborate network of dendrites—in nematode worms. The experiments show that the unfolded protein response is activated in these neurons as the dendrites form. Mutant worms that were missing a protein called IRE1, which can activate the unfolded protein response, had dendrites with fewer branches than normal worms. The experiments also show that a protein called DMA-1—which is required for dendrites to form—was not able to fold correctly in the mutant worms. As a result, this protein remained in the endoplasmic reticulum instead of moving to the surface of the cell where it is usually found. Wei et al.'s findings reveal that the unfolded protein response plays a major role in allowing cells to increase protein production as the dendrites form. The next challenge is to understand how neurons coordinate transcription and activation of the unfolded protein response. DOI:http://dx.doi.org/10.7554/eLife.06963.002
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Affiliation(s)
- Xing Wei
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
| | - Audrey S Howell
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
| | - Xintong Dong
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
| | - Caitlin A Taylor
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
| | - Roshni C Cooper
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
| | - Jianqi Zhang
- Division of Biostatistics, Department of Preventive Medicine, University of Southern California, Los Angeles, United States
| | - Wei Zou
- Department of Biology, Duke University, Durham, United States
| | | | - Kang Shen
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, United States
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Kang K, Ryoo HD, Park JE, Yoon JH, Kang MJ. A Drosophila Reporter for the Translational Activation of ATF4 Marks Stressed Cells during Development. PLoS One 2015; 10:e0126795. [PMID: 25978358 PMCID: PMC4433282 DOI: 10.1371/journal.pone.0126795] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 04/08/2015] [Indexed: 02/08/2023] Open
Abstract
Eukaryotic cells have evolved signaling pathways that help to restore cellular homeostasis in response to various physiological or pathological conditions. ATF4 is a transcription factor whose mRNA translation is stimulated in response to stress-activated eIF2alpha kinases. Established conditions that activate eIF2alpha phosphorylation and ATF4 translation include excessive stress in the endoplasmic reticulum (ER) and amino acid deprivation. ATF4 is activated through a unique translational activation mechanism that involves multiple upstream open reading frames (uORFs) in the 5’-untranslated region (UTR), which is conserved from yeast to mammals. Taking advantage of this, we developed a translational activation reporter of ATF4 in Drosophila, in which the dsRed reporter coding sequence was placed downstream of the Drosophila ATF4 5’ UTR. This reporter remained inactive in most tissues under normal conditions, but showed dsRed expression when starved, or when challenged with conditions that imposed ER stress. In normally developing flies, a small number of cell types showed reporter expression even without exogenous stress, which included the salivary gland, gut, the male reproductive organ, and the photoreceptor cells, suggestive of inherent stress during the normal development of these cell types. These results establish a new tool to study ATF4-mediated stress response in Drosophila development and disease.
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Affiliation(s)
- Kwonyoon Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America
| | - Jung-Eun Park
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Jee-Hyun Yoon
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Min-Ji Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
- * E-mail:
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Cleavage of BLOC1S1 mRNA by IRE1 Is Sequence Specific, Temporally Separate from XBP1 Splicing, and Dispensable for Cell Viability under Acute Endoplasmic Reticulum Stress. Mol Cell Biol 2015; 35:2186-202. [PMID: 25870107 PMCID: PMC4438243 DOI: 10.1128/mcb.00013-15] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/02/2015] [Indexed: 12/15/2022] Open
Abstract
The unfolded protein response (UPR) remediates endoplasmic reticulum (ER) stress. IRE1, a component of the UPR, senses misfolded protein and cleaves XBP1 mRNA, which is ligated to code for the prosurvival transcription factor. IRE1 also cleaves other mRNAs preceding their degradation, termed regulated IRE1-dependent mRNA decay (RIDD). It has been reported that RIDD may be involved in cell viability under stress and therefore may contribute to cancer cell viability. To investigate RIDD targets that may have functional relevance in cell survival, we identified conserved RIDD targets containing stringent IRE1 RNase target sequences. Using a systematic bioinformatics approach with quantitative-PCR (qPCR) validation, we show that only BLOC1S1 is consistently a RIDD target in all systems tested. Using cancer cell lines, we show that BLOC1S1 is specifically cleaved by IRE1 at guanine 444, but only under conditions of IRE1 hyperactivation. BLOC1S1 cleavage is temporally separate from XBP1 splicing, occurring after depletion of unspliced XBP1. Expression of an uncleavable BLOC1S1 mutant or inhibition of RIDD using an IRE1 RNase inhibitor did not affect cellular recovery from acute ER stress. These data demonstrate that although hyperactivated IRE1 specifically cleaves BLOC1S1, this cleavage event and RIDD as a whole are dispensable for cell viability under acute stress.
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Wu R, Zhang QH, Lu YJ, Ren K, Yi GH. Involvement of the IRE1α-XBP1 pathway and XBP1s-dependent transcriptional reprogramming in metabolic diseases. DNA Cell Biol 2015; 34:6-18. [PMID: 25216212 DOI: 10.1089/dna.2014.2552] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The X-box binding protein 1 (XBP1) is not only an important component of the unfolded protein response (UPR), but also an important nuclear transcription factor. Upon endoplasmic reticulum stress, XBP1 is spliced by inositol-requiring enzyme 1 (IRE1), thereby generating functional spliced XBP1 (XBP1s). XBP1s functions by translocating into the nucleus to initiate transcriptional programs that regulate a subset of UPR- and non-UPR-associated genes involved in the pathophysiological processes of various diseases. Recent reports have implicated XBP1 in metabolic diseases. This review summarizes the effects of XBP1-mediated regulation on lipid metabolism, glucose metabolism, obesity, and atherosclerosis. Additionally, for the first time, we present XBP1s-dependent transcriptional reprogramming in metabolic diseases under different conditions, including pathology and physiology. Understanding the function of XBP1 in metabolic diseases may provide a basic knowledge for the development of novel therapeutic targets for ameliorating these diseases.
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Affiliation(s)
- Rong Wu
- 1 Key Laboratory for Atherosclerology of Hunan Province, Institute of Cardiovascular Research, University of South China , Hengyang, China
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Jang BY, Ryoo HD, Son J, Choi KC, Shin DM, Kang SW, Kang MJ. Role of Drosophila EDEMs in the degradation of the alpha-1-antitrypsin Z variant. Int J Mol Med 2015; 35:870-6. [PMID: 25716426 PMCID: PMC4356437 DOI: 10.3892/ijmm.2015.2109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/18/2015] [Indexed: 02/05/2023] Open
Abstract
The synthesis of proteins in the endoplasmic reticulum (ER) that exceeds the protein folding capacity of this organelle is a frequent cause of cellular dysfunction and disease. An example of such a disease is alpha-1-antitrypsin (A1AT) deficiency, caused by destabilizing mutations in this glycoprotein. It is considered that the mutant proteins are recognized in the ER by lectins and are subsequently degraded through the proteasome, leading to a deficiency in this enzyme in the afflicted patients. We previously established a Drosophila model of this disease by overexpressing the null Hong Kong (NHK) allele of this gene and found that the Drosophila lectin, ER degradation-enhancing α-mannosidase-like protein 2 (EDEM2), can accelerate the degradation of A1AT when overexpressed. NHK is a rare allele, and in this study, we investigated in depth the mechanisms through which Drosophila EDEMs affect the degradation of the Z variant, which is the predominant disease allele. Specifically, we report that the Z allele does not activate ER stress signaling as prominently as the NHK allele, but similarly requires both Drosophila EDEM1 and EDEM2 for the degradation of the protein. We demonstrate that EDEMs are required for their ubiquitination, and without EDEMs, glycosylated A1AT mutants accumulate in cells. These results support the role of the EDEM-mediated ubiquitination of the alpha-1-antitrypsin Z (ATZ) allele, and establish a Drosophila model for the study of this protein and disease.
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Affiliation(s)
- Bo-Yun Jang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Jaekyoung Son
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea
| | - Kyung-Chul Choi
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea
| | - Dong-Myoung Shin
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea
| | - Sang-Wook Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea
| | - Min-Ji Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Republic of Korea
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Senft D, Ronai ZA. UPR, autophagy, and mitochondria crosstalk underlies the ER stress response. Trends Biochem Sci 2015; 40:141-8. [PMID: 25656104 DOI: 10.1016/j.tibs.2015.01.002] [Citation(s) in RCA: 742] [Impact Index Per Article: 82.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 12/29/2014] [Accepted: 01/06/2015] [Indexed: 12/18/2022]
Abstract
Cellular stress, induced by external or internal cues, activates several well-orchestrated processes aimed at either restoring cellular homeostasis or committing to cell death. Those processes include the unfolded protein response (UPR), autophagy, hypoxia, and mitochondrial function, which are part of the global endoplasmic reticulum (ER) stress (ERS) response. When one of the ERS elements is impaired, as often occurs under pathological conditions, overall cellular homeostasis may be perturbed. Further, activation of the UPR could trigger changes in mitochondrial function or autophagy, which could modulate the UPR, exemplifying crosstalk processes. Among the numerous factors that control the magnitude or duration of these processes are ubiquitin ligases, which govern overall cellular stress outcomes. Here we summarize crosstalk among the fundamental processes governing ERS responses.
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Affiliation(s)
- Daniela Senft
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA.
| | - Ze'ev A Ronai
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA.
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Haltom AR, Lee TV, Harvey BM, Leonardi J, Chen YJ, Hong Y, Haltiwanger RS, Jafar-Nejad H. The protein O-glucosyltransferase Rumi modifies eyes shut to promote rhabdomere separation in Drosophila. PLoS Genet 2014; 10:e1004795. [PMID: 25412384 PMCID: PMC4238978 DOI: 10.1371/journal.pgen.1004795] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 10/02/2014] [Indexed: 12/31/2022] Open
Abstract
The protein O-glucosyltransferase Rumi/POGLUT1 regulates Drosophila Notch signaling by adding O-glucose residues to the Notch extracellular domain. Rumi has other predicted targets including Crumbs (Crb) and Eyes shut (Eys), both of which are involved in photoreceptor development. However, whether Rumi is required for the function of Crb and Eys remains unknown. Here we report that in the absence of Rumi or its enzymatic activity, several rhabdomeres in each ommatidium fail to separate from one another in a Notch-independent manner. Mass spectral analysis indicates the presence of O-glucose on Crb and Eys. However, mutating all O-glucosylation sites in a crb knock-in allele does not cause rhabdomere attachment, ruling out Crb as a biologically-relevant Rumi target in this process. In contrast, eys and rumi exhibit a dosage-sensitive genetic interaction. In addition, although in wild-type ommatidia most of the Eys protein is found in the inter-rhabdomeral space (IRS), in rumi mutants a significant fraction of Eys remains in the photoreceptor cells. The intracellular accumulation of Eys and the IRS defect worsen in rumi mutants raised at a higher temperature, and are accompanied by a ∼50% decrease in the total level of Eys. Moreover, removing one copy of an endoplasmic reticulum chaperone enhances the rhabdomere attachment in rumi mutant animals. Altogether, our data suggest that O-glucosylation of Eys by Rumi ensures rhabdomere separation by promoting proper Eys folding and stability in a critical time window during the mid-pupal stage. Human EYS, which is mutated in patients with autosomal recessive retinitis pigmentosa, also harbors multiple Rumi target sites. Therefore, the role of O-glucose in regulating Eys may be conserved.
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Affiliation(s)
- Amanda R. Haltom
- Program in Genes & Development, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, United States of America
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tom V. Lee
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Beth M. Harvey
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Jessica Leonardi
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Yi-Jiun Chen
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Yang Hong
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Robert S. Haltiwanger
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Hamed Jafar-Nejad
- Program in Genes & Development, The University of Texas Graduate School of Biomedical Sciences, Houston, Texas, United States of America
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Heimel K. Unfolded protein response in filamentous fungi-implications in biotechnology. Appl Microbiol Biotechnol 2014; 99:121-32. [PMID: 25384707 DOI: 10.1007/s00253-014-6192-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 01/16/2023]
Abstract
The unfolded protein response (UPR) represents a mechanism to preserve endoplasmic reticulum (ER) homeostasis that is conserved in eukaryotes. ER stress caused by the accumulation of potentially toxic un- or misfolded proteins in the ER triggers UPR activation and the induction of genes important for protein folding in the ER, ER expansion, and transport from and to the ER. Along with this adaptation, the overall capacity for protein secretion is markedly increased by the UPR. In filamentous fungi, various approaches to employ the UPR for improved production of homologous and heterologous proteins have been investigated. As the effects on protein production were strongly dependent on the expressed protein, generally applicable strategies have to be developed. A combination of transcriptomic approaches monitoring secretion stress and basic research on the UPR mechanism provided novel and important insight into the complex regulatory cross-connections between UPR signalling, cellular physiology, and developmental processes. It will be discussed how this increasing knowledge on the UPR might stimulate the development of novel strategies for using the UPR as a tool in biotechnology.
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Affiliation(s)
- Kai Heimel
- Institut für Mikrobiologie & Genetik, Georg-August-Universität, Grisebachstr. 8, 37077, Göttingen, Germany,
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Raina K, Noblin DJ, Serebrenik YV, Adams A, Zhao C, Crews CM. Targeted protein destabilization reveals an estrogen-mediated ER stress response. Nat Chem Biol 2014; 10:957-62. [PMID: 25242550 PMCID: PMC4324732 DOI: 10.1038/nchembio.1638] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/14/2014] [Indexed: 12/16/2022]
Abstract
Accumulation of unfolded proteins within the endoplasmic reticulum (ER) of eukaryotic cells leads to an unfolded protein response (UPR) that either restores homeostasis or commits the cells to apoptosis. Tools traditionally used to study the UPR are proapoptotic and thus confound analysis of long-term cellular responses to ER stress. Here, we describe an ER-localized HaloTag (ERHT) protein that can be conditionally destabilized using a small-molecule hydrophobic tag (HyT36). Treatment of ERHT-expressing cells with HyT36 induces acute, resolvable ER stress that results in transient UPR activation without induction of apoptosis. Transcriptome analysis of late-stage responses to this UPR stimulus reveals a link between UPR activity and estrogen signaling.
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Affiliation(s)
- Kanak Raina
- 1] Department of Chemistry, Yale University New Haven, Connecticut, USA. [2]
| | - Devin J Noblin
- 1] Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, Connecticut, USA. [2]
| | - Yevgeniy V Serebrenik
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, Connecticut, USA
| | - Alison Adams
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, Connecticut, USA
| | - Connie Zhao
- Molecular Biophysics and Biochemistry, Yale University New Haven, Connecticut, USA
| | - Craig M Crews
- 1] Department of Chemistry, Yale University New Haven, Connecticut, USA. [2] Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, Connecticut, USA. [3] Department of Pharmacology, Yale University New Haven, Connecticut, USA
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