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Snanoudj S, Derambure C, Zhang C, Hai Yen NT, Lesueur C, Coutant S, Abily-Donval L, Marret S, Yang H, Mardinoglu A, Bekri S, Tebani A. Genome-wide expression analysis in a Fabry disease human podocyte cell line. Heliyon 2024; 10:e34357. [PMID: 39100494 PMCID: PMC11295972 DOI: 10.1016/j.heliyon.2024.e34357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 07/08/2024] [Accepted: 07/08/2024] [Indexed: 08/06/2024] Open
Abstract
Fabry disease (FD) is an X-linked lysosomal disease caused by an enzyme deficiency of alpha-galactosidase A (α-gal A). This deficiency leads to the accumulation of glycosphingolipids in lysosomes, resulting in a range of clinical symptoms. The complex pathogenesis of FD involves lysosomal dysfunction, altered autophagy, and mitochondrial abnormalities. Omics sciences, particularly transcriptomic analysis, comprehensively understand molecular mechanisms underlying diseases. This study focuses on genome-wide expression analysis in an FD human podocyte model to gain insights into the underlying mechanisms of podocyte dysfunction. Human control and GLA-edited podocytes were used. Gene expression data was generated using RNA-seq analysis, and differentially expressed genes were identified using DESeq2. Principal component analysis and Spearman correlation have explored gene expression trends. Functional enrichment and Reporter metabolite analyses were conducted to identify significantly affected metabolites and metabolic pathways. Differential expression analysis revealed 247 genes with altered expression levels in GLA-edited podocytes compared to control podocytes. Among these genes, 136 were underexpressed, and 111 were overexpressed in GLA-edited cells. Functional analysis of differentially expressed genes showed their involvement in various pathways related to oxidative stress, inflammation, fatty acid metabolism, collagen and extracellular matrix homeostasis, kidney injury, apoptosis, autophagy, and cellular stress response. The study provides insights into molecular mechanisms underlying Fabry podocyte dysfunction. Integrating transcriptomics data with genome-scale metabolic modeling further unveiled metabolic alterations in GLA-edited podocytes. This comprehensive approach contributes to a better understanding of Fabry disease and may lead to identifying new biomarkers and therapeutic targets for this rare lysosomal disorder.
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Affiliation(s)
- Sarah Snanoudj
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Metabolic Biochemistry, Referral Center for Lysosomal Diseases, Filière G2M, 76000, Rouen, France
| | - Céline Derambure
- Normandie Univ, UNIROUEN, INSERM U1245 and CHU Rouen, Department of Genetics and Reference Center for Developmental Disorders, FHU-G4 Génomique, F-76000, Rouen, France
| | - Cheng Zhang
- Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Nguyen Thi Hai Yen
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Metabolic Biochemistry, Referral Center for Lysosomal Diseases, Filière G2M, 76000, Rouen, France
| | - Céline Lesueur
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Metabolic Biochemistry, Referral Center for Lysosomal Diseases, Filière G2M, 76000, Rouen, France
| | - Sophie Coutant
- Normandie Univ, UNIROUEN, INSERM U1245 and CHU Rouen, Department of Genetics and Reference Center for Developmental Disorders, FHU-G4 Génomique, F-76000, Rouen, France
| | - Lénaïg Abily-Donval
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Neonatal Pediatrics, Intensive Care, and Neuropediatrics, 76000, Rouen, France
| | - Stéphane Marret
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Neonatal Pediatrics, Intensive Care, and Neuropediatrics, 76000, Rouen, France
| | - Hong Yang
- Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
| | - Adil Mardinoglu
- Science for Life Laboratory, KTH - Royal Institute of Technology, Stockholm, Sweden
- Centre for Host-Microbiome Interactions, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, London, United Kingdom
| | - Soumeya Bekri
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Metabolic Biochemistry, Referral Center for Lysosomal Diseases, Filière G2M, 76000, Rouen, France
| | - Abdellah Tebani
- Normandie Univ, UNIROUEN, INSERM, U1245, CHU Rouen, Department of Metabolic Biochemistry, Referral Center for Lysosomal Diseases, Filière G2M, 76000, Rouen, France
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2
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Mir DA, Ma Z, Horrocks J, Rogers AN. Stress-induced Eukaryotic Translational Regulatory Mechanisms. ARXIV 2024:arXiv:2405.01664v1. [PMID: 38745702 PMCID: PMC11092689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The eukaryotic protein synthesis process entails intricate stages governed by diverse mechanisms to tightly regulate translation. Translational regulation during stress is pivotal for maintaining cellular homeostasis, ensuring the accurate expression of essential proteins crucial for survival. This selective translational control mechanism is integral to cellular adaptation and resilience under adverse conditions. This review manuscript explores various mechanisms involved in selective translational regulation, focusing on mRNA-specific and global regulatory processes. Key aspects of translational control include translation initiation, which is often a rate-limiting step, and involves the formation of the eIF4F complex and recruitment of mRNA to ribosomes. Regulation of translation initiation factors, such as eIF4E, eIF4E2, and eIF2, through phosphorylation and interactions with binding proteins, modulates translation efficiency under stress conditions. This review also highlights the control of translation initiation through factors like the eIF4F complex and the ternary complex and also underscores the importance of eIF2α phosphorylation in stress granule formation and cellular stress responses. Additionally, the impact of amino acid deprivation, mTOR signaling, and ribosome biogenesis on translation regulation and cellular adaptation to stress is also discussed. Understanding the intricate mechanisms of translational regulation during stress provides insights into cellular adaptation mechanisms and potential therapeutic targets for various diseases, offering valuable avenues for addressing conditions associated with dysregulated protein synthesis.
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Affiliation(s)
- Dilawar Ahmad Mir
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
| | - Zhengxin Ma
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
| | - Jordan Horrocks
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
| | - Aric N Rogers
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
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3
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Chousal JN, Sohni A, Vitting-Seerup K, Cho K, Kim M, Tan K, Porse B, Wilkinson MF, Cook-Andersen H. Progression of the pluripotent epiblast depends upon the NMD factor UPF2. Development 2022; 149:dev200764. [PMID: 36255229 PMCID: PMC9687065 DOI: 10.1242/dev.200764] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 09/09/2022] [Indexed: 11/09/2022]
Abstract
Nonsense-mediated RNA decay (NMD) is a highly conserved RNA turnover pathway that degrades RNAs harboring in-frame stop codons in specific contexts. Loss of NMD factors leads to embryonic lethality in organisms spanning the phylogenetic scale, but the mechanism remains unknown. Here, we report that the core NMD factor, UPF2, is required for expansion of epiblast cells within the inner cell mass of mice in vivo. We identify NMD target mRNAs in mouse blastocysts - both canonical and alternatively processed mRNAs - including those encoding cell cycle arrest and apoptosis factors, raising the possibility that NMD is essential for embryonic cell proliferation and survival. In support, the inner cell mass of Upf2-null blastocysts rapidly regresses with outgrowth and is incompetent for embryonic stem cell derivation in vitro. In addition, we uncovered concordant temporal- and lineage-specific regulation of NMD factors and mRNA targets, indicative of a shift in NMD magnitude during peri-implantation development. Together, our results reveal developmental and molecular functions of the NMD pathway in the early embryo.
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Affiliation(s)
- Jennifer N. Chousal
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Abhishek Sohni
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kristoffer Vitting-Seerup
- The Bioinformatics Centre, Department of Biology and Biotech Research & Innovation Centre, University of Copenhagen, 2200 Copenhagen, Denmark
- Section for Bioinformatics, Health Technology, Technical University of Denmark (DTU), 2800 Kongens Lyngby, Denmark
| | - Kyucheol Cho
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Matthew Kim
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kun Tan
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Bo Porse
- The Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, DK2200 Copenhagen, Denmark
- Biotech Research and Innovation Center (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark
- Novo Nordisk Foundation Center for Stem Cell Biology, DanStem, Faculty of Health Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Miles F. Wilkinson
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Institute of Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Heidi Cook-Andersen
- Department of Obstetrics, Gynecology and Reproductive Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Molecular Biology, University of California, San Diego, La Jolla, CA 92093, USA
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4
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A Novel Role of SMG1 in Cholesterol Homeostasis That Depends Partially on p53 Alternative Splicing. Cancers (Basel) 2022; 14:cancers14133255. [PMID: 35805027 PMCID: PMC9265556 DOI: 10.3390/cancers14133255] [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] [Received: 05/31/2022] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 12/10/2022] Open
Abstract
Simple Summary p53 isoforms have been reported in various tumor types. Both p53β and p53γ were recently reported to retain functionalities of full-length p53α. A role for p53 and p53 loss in cholesterol metabolism has also emerged. We show that SMG1, a phosphatidylinositol 3-kinase-related kinase, when inhibited in p53 wild-type MCF7 and HepG2 cells, significantly alters the expression of cholesterol pathway genes, with a net increase in intracellular cholesterol and an increased sensitivity to Fatostatin in MCF7. We confirm a prior report that SMG1 inhibition in MCF7 cells promotes expression of p53β and show the first evidence for increases in p53γ. Further, induced p53β expression, confirmed with antibody, explained the loss of SMG1 upregulation of the ABCA1 cholesterol exporter where p53γ had no effect on ABCA1. Additionally, upregulation of ABCA1 upon SMG1 knockdown was independent of upregulation of nonsense-mediated decay target RASSF1C, previously suggested to regulate ABCA1 via a “RASSF1C-miR33a-ABCA1” axis. Abstract SMG1, a phosphatidylinositol 3-kinase-related kinase (PIKK), essential in nonsense-mediated RNA decay (NMD), also regulates p53, including the alternative splicing of p53 isoforms reported to retain p53 functions. We confirm that SMG1 inhibition in MCF7 tumor cells induces p53β and show p53γ increase. Inhibiting SMG1, but not UPF1 (a core factor in NMD), upregulated several cholesterol pathway genes. SMG1 knockdown significantly increased ABCA1, a cholesterol efflux pump shown to be positively regulated by full-length p53 (p53α). An investigation of RASSF1C, an NMD target, increased following SMG1 inhibition and reported to inhibit miR-33a-5p, a canonical ABCA1-inhibiting miRNA, did not explain the ABCA1 results. ABCA1 upregulation following SMG1 knockdown was inhibited by p53β siRNA with greatest inhibition when p53α and p53β were jointly suppressed, while p53γ siRNA had no effect. In contrast, increased expression of MVD, a cholesterol synthesis gene upregulated in p53 deficient backgrounds, was sensitive to combined targeting of p53α and p53γ. Phenotypically, we observed increased intracellular cholesterol and enhanced sensitivity of MCF7 to growth inhibitory effects of cholesterol-lowering Fatostatin following SMG1 inhibition. Our results suggest deregulation of cholesterol pathway genes following SMG1 knockdown may involve alternative p53 programming, possibly resulting from differential effects of p53 isoforms on cholesterol gene expression.
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Kamp JA, Lemmens BBLG, Romeijn RJ, González-Prieto R, Olsen J, Vertegaal ACO, van Schendel R, Tijsterman M. THO complex deficiency impairs DNA double-strand break repair via the RNA surveillance kinase SMG-1. Nucleic Acids Res 2022; 50:6235-6250. [PMID: 35670662 PMCID: PMC9226523 DOI: 10.1093/nar/gkac472] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 05/11/2022] [Accepted: 06/02/2022] [Indexed: 12/25/2022] Open
Abstract
The integrity and proper expression of genomes are safeguarded by DNA and RNA surveillance pathways. While many RNA surveillance factors have additional functions in the nucleus, little is known about the incidence and physiological impact of converging RNA and DNA signals. Here, using genetic screens and genome-wide analyses, we identified unforeseen SMG-1-dependent crosstalk between RNA surveillance and DNA repair in living animals. Defects in RNA processing, due to viable THO complex or PNN-1 mutations, induce a shift in DNA repair in dividing and non-dividing tissues. Loss of SMG-1, an ATM/ATR-like kinase central to RNA surveillance by nonsense-mediated decay (NMD), restores DNA repair and radio-resistance in THO-deficient animals. Mechanistically, we find SMG-1 and its downstream target SMG-2/UPF1, but not NMD per se, to suppress DNA repair by non-homologous end-joining in favour of single strand annealing. We postulate that moonlighting proteins create short-circuits in vivo, allowing aberrant RNA to redirect DNA repair.
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Affiliation(s)
| | | | - Ron J Romeijn
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, The Netherlands
| | - Román González-Prieto
- Department of Cell & Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Jesper V Olsen
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark
| | - Alfred C O Vertegaal
- Department of Cell & Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC, Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, The Netherlands
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6
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Abstract
Nonsense-mediated mRNA decay (NMD) is an mRNA degradation pathway that eliminates transcripts containing premature termination codons (PTCs). Half-lives of the mRNAs containing PTCs demonstrate that a small percent escape surveillance and do not degrade. It is not known whether this escape represents variable mRNA degradation within cells or, alternatively cells within the population are resistant. Here we demonstrate a single-cell approach with a bi-directional reporter, which expresses two β-globin genes with or without a PTC in the same cell, to characterize the efficiency of NMD in individual cells. We found a broad range of NMD efficiency in the population; some cells degraded essentially all of the mRNAs, while others escaped NMD almost completely. Characterization of NMD efficiency together with NMD regulators in single cells showed cell-to-cell variability of NMD reflects the differential level of surveillance factors, SMG1 and phosphorylated UPF1. A single-cell fluorescent reporter system that enabled detection of NMD using flow cytometry revealed that this escape occurred either by translational readthrough at the PTC or by a failure of mRNA degradation after successful translation termination at the PTC.
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7
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Ho U, Luff J, James A, Lee CS, Quek H, Lai HC, Apte S, Lim YC, Lavin MF, Roberts TL. SMG1 heterozygosity exacerbates haematopoietic cancer development in Atm null mice by increasing persistent DNA damage and oxidative stress. J Cell Mol Med 2019; 23:8151-8160. [PMID: 31565865 PMCID: PMC6850945 DOI: 10.1111/jcmm.14685] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/25/2019] [Accepted: 05/15/2019] [Indexed: 12/20/2022] Open
Abstract
Suppressor of morphogenesis in genitalia 1 (SMG1) and ataxia telangiectasia mutated (ATM) are members of the PI3‐kinase like–kinase (PIKK) family of proteins. ATM is a well‐established tumour suppressor. Loss of one or both alleles of ATM results in an increased risk of cancer development, particularly haematopoietic cancer and breast cancer in both humans and mouse models. In mice, total loss of SMG1 is embryonic lethal and loss of a single allele results in an increased rate of cancer development, particularly haematopoietic cancers and lung cancer. In this study, we generated mice deficient in Atm and lacking one allele of Smg1, Atm−/−Smg1gt/+ mice. These mice developed cancers more rapidly than either of the parental genotypes, and all cancers were haematopoietic in origin. The combined loss of Smg1 and Atm resulted in a higher level of basal DNA damage and oxidative stress in tissues than loss of either gene alone. Furthermore, Atm−/−Smg1gt/+ mice displayed increased cytokine levels in haematopoietic tissues compared with wild‐type animals indicating the development of low‐level inflammation and a pro‐tumour microenvironment. Overall, our data demonstrated that combined loss of Atm expression and decreased Smg1 expression increases haematopoietic cancer development.
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Affiliation(s)
- Uda Ho
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, St Lucia, Qld, Australia
| | - John Luff
- UQCCR, University of Queensland, Brisbane, Qld, Australia
| | - Alexander James
- The Ingham Institute for Applied Medical Research and School of Medicine, Western Sydney University, Liverpool, NSW, Australia
| | - Cheok Soon Lee
- The Ingham Institute for Applied Medical Research and School of Medicine, Western Sydney University, Liverpool, NSW, Australia.,South West Sydney Clinical School, UNSW Sydney, Liverpool, NSW, Australia.,Department of Anatomical Pathology, Molecular Pathology Laboratory, Liverpool Hospital, Liverpool, NSW, Australia
| | - Hazel Quek
- UQCCR, University of Queensland, Brisbane, Qld, Australia.,QIMR Berghofer Medical Research Institute, Herston, Qld, Australia
| | - Hui-Chi Lai
- The Ingham Institute for Applied Medical Research and School of Medicine, Western Sydney University, Liverpool, NSW, Australia.,South West Sydney Clinical School, UNSW Sydney, Liverpool, NSW, Australia
| | - Simon Apte
- QIMR Berghofer Medical Research Institute, Herston, Qld, Australia
| | - Yi Chieh Lim
- QIMR Berghofer Medical Research Institute, Herston, Qld, Australia.,Danish Cancer Society Research Centre, Copenhagen, Denmark
| | - Martin F Lavin
- UQCCR, University of Queensland, Brisbane, Qld, Australia
| | - Tara L Roberts
- UQCCR, University of Queensland, Brisbane, Qld, Australia.,The Ingham Institute for Applied Medical Research and School of Medicine, Western Sydney University, Liverpool, NSW, Australia.,South West Sydney Clinical School, UNSW Sydney, Liverpool, NSW, Australia
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8
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Wong C, Chen F, Alirezaie N, Wang Y, Cuggia A, Borgida A, Holter S, Lenko T, Domecq C, Petersen GM, Syngal S, Brand R, Rustgi AK, Cote ML, Stoffel E, Olson SH, Roberts NJ, Akbari MR, Majewski J, Klein AP, Greenwood CMT, Gallinger S, Zogopoulos G. A region-based gene association study combined with a leave-one-out sensitivity analysis identifies SMG1 as a pancreatic cancer susceptibility gene. PLoS Genet 2019; 15:e1008344. [PMID: 31469826 PMCID: PMC6742418 DOI: 10.1371/journal.pgen.1008344] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 09/12/2019] [Accepted: 08/03/2019] [Indexed: 12/18/2022] Open
Abstract
Pancreatic adenocarcinoma (PC) is a lethal malignancy that is familial or associated with genetic syndromes in 10% of cases. Gene-based surveillance strategies for at-risk individuals may improve clinical outcomes. However, familial PC (FPC) is plagued by genetic heterogeneity and the genetic basis for the majority of FPC remains elusive, hampering the development of gene-based surveillance programs. The study was powered to identify genes with a cumulative pathogenic variant prevalence of at least 3%, which includes the most prevalent PC susceptibility gene, BRCA2. Since the majority of known PC susceptibility genes are involved in DNA repair, we focused on genes implicated in these pathways. We performed a region-based association study using the Mixed-Effects Score Test, followed by leave-one-out characterization of PC-associated gene regions and variants to identify the genes and variants driving risk associations. We evaluated 398 cases from two case series and 987 controls without a personal history of cancer. The first case series consisted of 109 patients with either FPC (n = 101) or PC at ≤50 years of age (n = 8). The second case series was composed of 289 unselected PC cases. We validated this discovery strategy by identifying known pathogenic BRCA2 variants, and also identified SMG1, encoding a serine/threonine protein kinase, to be significantly associated with PC following correction for multiple testing (p = 3.22x10-7). The SMG1 association was validated in a second independent series of 532 FPC cases and 753 controls (p<0.0062, OR = 1.88, 95%CI 1.17-3.03). We showed segregation of the c.4249A>G SMG1 variant in 3 affected relatives in a FPC kindred, and we found c.103G>A to be a recurrent SMG1 variant associating with PC in both the discovery and validation series. These results suggest that SMG1 is a novel PC susceptibility gene, and we identified specific SMG1 gene variants associated with PC risk.
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Affiliation(s)
- Cavin Wong
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Fei Chen
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Najmeh Alirezaie
- McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada
| | - Yifan Wang
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Adeline Cuggia
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Ayelet Borgida
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Spring Holter
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Tatiana Lenko
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Celine Domecq
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | | | - Gloria M. Petersen
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Sapna Syngal
- Division of Cancer Genetics and Prevention, Dana-Farber Cancer Institute, Gastroenterology Division, Brigham and Women’s Hospital, Harvard Medical Schozol, Boston, Massachusetts, United States of America
| | - Randall Brand
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Anil K. Rustgi
- Division of Gastroenterology, Departments of Medicine and Genetics, Pancreatic Cancer Translation Center of Excellence, Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Michele L. Cote
- Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Elena Stoffel
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sara H. Olson
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Nicholas J. Roberts
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland, United States of America
- The Sol Goldman Pancreatic Cancer Research Center, Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mohammad R. Akbari
- Women’s College Hospital Research Institute, Women's College Hospital, Toronto, Ontario, Canada
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Jacek Majewski
- McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada
| | - Alison P. Klein
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland, United States of America
- The Sol Goldman Pancreatic Cancer Research Center, Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Celia M. T. Greenwood
- Ludmer Centre for Neuroinformatics & Mental Health, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
- Gerald Bronfman Department of Oncology, and Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada
| | - Steven Gallinger
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - George Zogopoulos
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
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9
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Lloyd JPB, Lang D, Zimmer AD, Causier B, Reski R, Davies B. The loss of SMG1 causes defects in quality control pathways in Physcomitrella patens. Nucleic Acids Res 2019; 46:5822-5836. [PMID: 29596649 PMCID: PMC6009662 DOI: 10.1093/nar/gky225] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 03/16/2018] [Indexed: 12/16/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is important for RNA quality control and gene regulation in eukaryotes. NMD targets aberrant transcripts for decay and also directly influences the abundance of non-aberrant transcripts. In animals, the SMG1 kinase plays an essential role in NMD by phosphorylating the core NMD factor UPF1. Despite SMG1 being ubiquitous throughout the plant kingdom, little is known about its function, probably because SMG1 is atypically absent from the genome of the model plant, Arabidopsis thaliana. By combining our previously established SMG1 knockout in moss with transcriptome-wide analysis, we reveal the range of processes involving SMG1 in plants. Machine learning assisted analysis suggests that 32% of multi-isoform genes produce NMD-targeted transcripts and that splice junctions downstream of a stop codon act as the major determinant of NMD targeting. Furthermore, we suggest that SMG1 is involved in other quality control pathways, affecting DNA repair and the unfolded protein response, in addition to its role in mRNA quality control. Consistent with this, smg1 plants have increased susceptibility to DNA damage, but increased tolerance to unfolded protein inducing agents. The potential involvement of SMG1 in RNA, DNA and protein quality control has major implications for the study of these processes in plants.
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Affiliation(s)
- James P B Lloyd
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, UK
| | - Daniel Lang
- Plant Biotechnology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Andreas D Zimmer
- Plant Biotechnology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Barry Causier
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, UK
| | - Ralf Reski
- Plant Biotechnology, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.,BIOSS - Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Brendan Davies
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, UK
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10
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Han X, Wei Y, Wang H, Wang F, Ju Z, Li T. Nonsense-mediated mRNA decay: a 'nonsense' pathway makes sense in stem cell biology. Nucleic Acids Res 2019; 46:1038-1051. [PMID: 29272451 PMCID: PMC5814811 DOI: 10.1093/nar/gkx1272] [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: 08/14/2017] [Accepted: 12/09/2017] [Indexed: 01/04/2023] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a highly conserved post-transcriptional regulatory mechanism of gene expression in eukaryotes. Originally, NMD was identified as an RNA surveillance machinery in degrading 'aberrant' mRNA species with premature termination codons. Recent studies indicate that NMD regulates the stability of natural gene transcripts that play significant roles in cell functions. Although components and action modes of the NMD machinery in degrading its RNA targets have been extensively studied with biochemical and structural approaches, the biological roles of NMD remain to be defined. Stem cells are rare cell populations, which play essential roles in tissue homeostasis and hold great promises in regenerative medicine. Stem cells self-renew to maintain the cellular identity and differentiate into somatic lineages with specialized functions to sustain tissue integrity. Transcriptional regulations and epigenetic modulations have been extensively implicated in stem cell biology. However, post-transcriptional regulatory mechanisms, such as NMD, in stem cell regulation are largely unknown. In this paper, we summarize the recent findings on biological roles of NMD factors in embryonic and tissue-specific stem cells. Furthermore, we discuss the possible mechanisms of NMD in regulating stem cell fates.
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Affiliation(s)
- Xin Han
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Yanling Wei
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Hua Wang
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Feilong Wang
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Zhenyu Ju
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
| | - Tangliang Li
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China
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11
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Yee M, Cohen ED, Domm W, Porter GA, McDavid AN, O’Reilly MA. Neonatal hyperoxia depletes pulmonary vein cardiomyocytes in adult mice via mitochondrial oxidation. Am J Physiol Lung Cell Mol Physiol 2018; 314:L846-L859. [PMID: 29345197 PMCID: PMC6008126 DOI: 10.1152/ajplung.00409.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Supplemental oxygen given to preterm infants has been associated with permanently altering postnatal lung development. Now that these individuals are reaching adulthood, there is growing concern that early life oxygen exposure may also promote cardiovascular disease through poorly understood mechanisms. We previously reported that adult mice exposed to 100% oxygen between postnatal days 0 and 4 develop pulmonary hypertension, defined pathologically by capillary rarefaction, dilation of arterioles and veins, cardiac failure, and a reduced lifespan. Here, Affymetrix Gene Arrays are used to identify early transcriptional changes that take place in the lung before pulmonary capillary rarefaction. We discovered neonatal hyperoxia reduced expression of cardiac muscle genes, including those involved in contraction, calcium signaling, mitochondrial respiration, and vasodilation. Quantitative RT-PCR, immunohistochemistry, and genetic lineage mapping using Myh6CreER; Rosa26RmT/mG mice revealed this reflected loss of pulmonary vein cardiomyocytes. The greatest loss of cadiomyocytes was seen within the lung followed by a graded loss beginning at the hilum and extending into the left atrium. Loss of these cells was seen by 2 wk of age in mice exposed to ≥80% oxygen and was attributed, in part, to reduced proliferation. Administering mitoTEMPO, a scavenger of mitochondrial superoxide during neonatal hyperoxia prevented loss of these cells. Since pulmonary vein cardiomyocytes help pump oxygen-rich blood out of the lung, their early loss following neonatal hyperoxia may contribute to cardiovascular disease seen in these mice, and perhaps in people who were born preterm.
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Affiliation(s)
- Min Yee
- 1Department of Pediatrics, School of Medicine and Dentistry, The University of Rochester, Rochester, New York
| | - Ethan David Cohen
- 2Department of Medicine, School of Medicine and Dentistry, The University of Rochester, Rochester, New York
| | - William Domm
- 1Department of Pediatrics, School of Medicine and Dentistry, The University of Rochester, Rochester, New York
| | - George A. Porter
- 1Department of Pediatrics, School of Medicine and Dentistry, The University of Rochester, Rochester, New York
| | - Andrew N. McDavid
- 3Biostatistics and Computational Biology, School of Medicine and Dentistry, The University of Rochester, Rochester, New York
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12
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Quek H, Lim YC, Lavin MF, Roberts TL. PIKKing a way to regulate inflammation. Immunol Cell Biol 2017; 96:8-20. [DOI: 10.1111/imcb.1001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/31/2017] [Accepted: 09/02/2017] [Indexed: 12/26/2022]
Affiliation(s)
- Hazel Quek
- The University of Queensland Centre for Clinical Research; Herston Qld Australia
- QIMR Berghofer Medical Research Institute; Herston Qld Australia
| | - Yi Chieh Lim
- QIMR Berghofer Medical Research Institute; Herston Qld Australia
| | - Martin F Lavin
- The University of Queensland Centre for Clinical Research; Herston Qld Australia
| | - Tara L Roberts
- The University of Queensland Centre for Clinical Research; Herston Qld Australia
- The Ingham Institute for Applied Medical Research and School of Medicine; Western Sydney University; Liverpool New South Wales Australia
- South West Sydney Clinical School; Sydney UNSW Australia
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13
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Resseguie EA, Brookes PS, O’Reilly MA. SMG-1 kinase attenuates mitochondrial ROS production but not cell respiration deficits during hyperoxia. Exp Lung Res 2017; 43:229-239. [PMID: 28749708 PMCID: PMC5956894 DOI: 10.1080/01902148.2017.1339143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 06/02/2017] [Indexed: 12/29/2022]
Abstract
PURPOSE Supplemental oxygen (hyperoxia) used to treat individuals in respiratory distress causes cell injury by enhancing the production of toxic reactive oxygen species (ROS) and inhibiting mitochondrial respiration. The suppressor of morphogenesis of genitalia (SMG-1) kinase is activated during hyperoxia and promotes cell survival by phosphorylating the tumor suppressor p53 on serine 15. Here, we investigate whether SMG-1 and p53 blunt this vicious cycle of progressive ROS production and decline in mitochondrial respiration seen during hyperoxia. MATERIALS AND METHODS Human lung adenocarcinoma A549 and H1299 or colon carcinoma HCT116 cells were depleted of SMG-1, UPF-1, or p53 using RNA interference, and then exposed to room air (21% oxygen) or hyperoxia (95% oxygen). Immunoblotting was used to evaluate protein expression; a Seahorse Bioanalyzer was used to assess cellular respiration; and flow cytometry was used to evaluate fluorescence intensity of cells stained with mitochondrial or redox sensitive dyes. RESULTS Hyperoxia increased mitochondrial and cytoplasmic ROS and suppressed mitochondrial respiration without changing mitochondrial mass or membrane potential. Depletion of SMG-1 or its cofactor, UPF1, significantly enhanced hyperoxia-induced mitochondrial but not cytosolic ROS abundance. They did not affect mitochondrial mass, membrane potential, or hyperoxia-induced deficits in mitochondrial respiration. Genetic depletion of p53 in A549 cells and ablation of the p53 gene in H1299 or HCT116 cells revealed that SMG-1 influences mitochondrial ROS through activation of p53. CONCLUSIONS Our findings show that hyperoxia does not promote a vicious cycle of progressive mitochondrial ROS and dysfunction because SMG-1-p53 signaling attenuates production of mitochondrial ROS without preserving respiration. This suggests antioxidant therapies that blunt ROS production during hyperoxia may not suffice to restore cellular respiration.
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Affiliation(s)
- Emily A. Resseguie
- Department of Environmental Medicine, The University of Rochester, Rochester, New York, USA
| | - Paul S. Brookes
- Department of Anesthesiology, The University of Rochester, Rochester, New York, USA
| | - Michael A. O’Reilly
- Department of Environmental Medicine, The University of Rochester, Rochester, New York, USA
- Department of Pediatrics, The University of Rochester, Rochester, New York, USA
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14
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Resseguie EA, Staversky RJ, Brookes PS, O'Reilly MA. Hyperoxia activates ATM independent from mitochondrial ROS and dysfunction. Redox Biol 2015; 5:176-185. [PMID: 25967673 PMCID: PMC4430709 DOI: 10.1016/j.redox.2015.04.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 04/25/2015] [Indexed: 01/12/2023] Open
Abstract
High levels of oxygen (hyperoxia) are often used to treat individuals with respiratory distress, yet prolonged hyperoxia causes mitochondrial dysfunction and excessive reactive oxygen species (ROS) that can damage molecules such as DNA. Ataxia telangiectasia mutated (ATM) kinase is activated by nuclear DNA double strand breaks and delays hyperoxia-induced cell death through downstream targets p53 and p21. Evidence for its role in regulating mitochondrial function is emerging, yet it has not been determined if mitochondrial dysfunction or ROS activates ATM. Because ATM maintains mitochondrial homeostasis, we hypothesized that hyperoxia induces both mitochondrial dysfunction and ROS that activate ATM. In A549 lung epithelial cells, hyperoxia decreased mitochondrial respiratory reserve capacity at 12h and basal respiration by 48 h. ROS were significantly increased at 24h, yet mitochondrial DNA double strand breaks were not detected. ATM was not required for activating p53 when mitochondrial respiration was inhibited by chronic exposure to antimycin A. Also, ATM was not further activated by mitochondrial ROS, which were enhanced by depleting manganese superoxide dismutase (SOD2). In contrast, ATM dampened the accumulation of mitochondrial ROS during exposure to hyperoxia. Our findings suggest that hyperoxia-induced mitochondrial dysfunction and ROS do not activate ATM. ATM more likely carries out its canonical response to nuclear DNA damage and may function to attenuate mitochondrial ROS that contribute to oxygen toxicity.
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Affiliation(s)
- Emily A Resseguie
- Department of Environmental Medicine, University of Rochester, Rochester, NY 14642, USA
| | - Rhonda J Staversky
- Department of Pediatrics, University of Rochester, Rochester, NY 14642, USA
| | - Paul S Brookes
- Department of Anesthesiology, University of Rochester, Rochester, NY 14642, USA
| | - Michael A O'Reilly
- Department of Environmental Medicine, University of Rochester, Rochester, NY 14642, USA; Department of Pediatrics, University of Rochester, Rochester, NY 14642, USA.
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15
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Zou D, McSweeney C, Sebastian A, Reynolds DJ, Dong F, Zhou Y, Deng D, Wang Y, Liu L, Zhu J, Zou J, Shi Y, Albert I, Mao Y. A critical role of RBM8a in proliferation and differentiation of embryonic neural progenitors. Neural Dev 2015; 10:18. [PMID: 26094033 PMCID: PMC4479087 DOI: 10.1186/s13064-015-0045-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 06/17/2015] [Indexed: 02/04/2023] Open
Abstract
Background Nonsense mediated mRNA decay (NMD) is an RNA surveillance mechanism that controls RNA stability and ensures the speedy degradation of erroneous and unnecessary transcripts. This mechanism depends on several core factors in the exon junction complex (EJC), eIF4A3, RBM8a, Magoh, and BTZ, as well as peripheral factors to distinguish premature stop codons (PTCs) from normal stop codons in transcripts. Recently, emerging evidence has indicated that NMD factors are associated with neurodevelopmental disorders such as autism spectrum disorder (ASD) and intellectual disability (ID). However, the mechanism in which these factors control embryonic brain development is not clear. Result We found that RBM8a is critical for proliferation and differentiation in cortical neural progenitor cells (NPCs). RBM8a is highly expressed in the subventricular zone (SVZ) of the early embryonic cortex, suggesting that RBM8a may play a role in regulating NPCs. RBM8a overexpression stimulates embryonic NPC proliferation and suppresses neuronal differentiation. Conversely, knockdown of RBM8a in the neocortex reduces NPC proliferation and promotes premature neuronal differentiation. Moreover, overexpression of RBM8a suppresses cell cycle exit and keeps cortical NPCs in a proliferative state. To uncover the underlying mechanisms of this phenotype, genome-wide RNAseq was used to identify potential downstream genes of RBM8a in the brain, which have been implicated in autism and neurodevelopmental disorders. Interestingly, autism and schizophrenia risk genes are highly represented in downstream transcripts of RBM8a. In addition, RBM8a regulates multiple alternative splicing genes and NMD targets that are implicated in ASD. Taken together, this data suggests a novel role of RBM8a in the regulation of neurodevelopment. Conclusions Our studies provide some insight into causes of mental illnesses and will facilitate the development of new therapeutic strategies for neurodevelopmental illnesses. Electronic supplementary material The online version of this article (doi:10.1186/s13064-015-0045-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Donghua Zou
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Province, 530021, China. .,Department of Geriatrics, The 303 Hospital of Chinese People's Liberation Army, Nanning, Guangxi Province, 530021, China. .,Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Colleen McSweeney
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Aswathy Sebastian
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Derrick James Reynolds
- Department of Microbiology & Molecular Genetics School of Medicine, University of California, Irvine, CA, 92697, USA.
| | - Fengping Dong
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Yijing Zhou
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Dazhi Deng
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Emergency, Guangxi Zhuang Autonomous Region People's Hospital, Nanning, Guangxi Province, 530021, China.
| | - Yonggang Wang
- Department of Neurology, School of Medicine, Renji Hospital, Shanghai Jiaotong University, Shanghai, 200127, China.
| | - Long Liu
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Chemistry and Biology, College of Science, National University of Defense Technology, Changsha, 410073, China.
| | - Jun Zhu
- Systems Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, 20892, USA.
| | - Jizhong Zou
- Center for Molecular Medicine, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, 20892, USA.
| | - Yongsheng Shi
- Department of Microbiology & Molecular Genetics School of Medicine, University of California, Irvine, CA, 92697, USA.
| | - Istvan Albert
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA.
| | - Yingwei Mao
- Department of Neurology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Province, 530021, China. .,Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.
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16
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Yuan Z, Guo W, Yang J, Li L, Wang M, Lei Y, Wan Y, Zhao X, Luo N, Cheng P, Liu X, Nie C, Peng Y, Tong A, Wei Y. PNAS-4, an Early DNA Damage Response Gene, Induces S Phase Arrest and Apoptosis by Activating Checkpoint Kinases in Lung Cancer Cells. J Biol Chem 2015; 290:14927-44. [PMID: 25918161 DOI: 10.1074/jbc.m115.658419] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Indexed: 02/05/2023] Open
Abstract
PNAS-4, a novel pro-apoptotic gene, was activated during the early response to DNA damage. Our previous study has shown that PNAS-4 induces S phase arrest and apoptosis when overexpressed in A549 lung cancer cells. However, the underlying action mechanism remains far from clear. In this work, we found that PNAS-4 expression in lung tumor tissues is significantly lower than that in adjacent lung tissues; its expression is significantly increased in A549 cells after exposure to cisplatin, methyl methane sulfonate, and mitomycin; and its overexpression induces S phase arrest and apoptosis in A549 (p53 WT), NCI-H460 (p53 WT), H526 (p53 mutation), and Calu-1 (p53(-/-)) lung cancer cells, leading to proliferation inhibition irrespective of their p53 status. The S phase arrest is associated with up-regulation of p21(Waf1/Cip1) and inhibition of the Cdc25A-CDK2-cyclin E/A pathway. Up-regulation of p21(Waf1/Cip1) is p53-independent and correlates with activation of ERK. We further showed that the intra-S phase checkpoint, which occurs via DNA-dependent protein kinase-mediated activation of Chk1 and Chk2, is involved in the S phase arrest and apoptosis. Gene silencing of Chk1/2 rescues, whereas that of ATM or ATR does not affect, S phase arrest and apoptosis. Furthermore, human PNAS-4 induces DNA breaks in comet assays and γ-H2AX staining. Intriguingly, caspase-dependent cleavage of Chk1 has an additional role in enhancing apoptosis. Taken together, our findings suggest a novel mechanism by which elevated PNAS-4 first causes DNA-dependent protein kinase-mediated Chk1/2 activation and then results in inhibition of the Cdc25A-CDK2-cyclin E/A pathway, ultimately causing S phase arrest and apoptosis in lung cancer cells.
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Affiliation(s)
- Zhu Yuan
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China,
| | - Wenhao Guo
- the Department of Abdominal Oncology, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, No. 37, Guoxue Road, Chengdu 610041, Sichuan Province, China, and
| | - Jun Yang
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Lei Li
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Meiliang Wang
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Yi Lei
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Yang Wan
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Xinyu Zhao
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Na Luo
- the Nankai University School of Medicine/Collaborative Innovation Center of Biotherapy, Tianjin 300071, China
| | - Ping Cheng
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Xinyu Liu
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Chunlai Nie
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Yong Peng
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
| | - Aiping Tong
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China,
| | - Yuquan Wei
- From the State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University/Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, 17 People's South Road, Chengdu 610041, China
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17
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Wang Q, Xu D, Han C, Tu M, Du Q, Zhang J, Zhu Y, Xu L. Overexpression of serine/threonine-protein kinase-1 in pancreatic cancer tissue: Serine/threonine-protein kinase-1 knockdown increases the chemosensitivity of pancreatic cancer cells. Mol Med Rep 2015; 12:475-81. [PMID: 25760059 DOI: 10.3892/mmr.2015.3434] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 01/29/2015] [Indexed: 11/06/2022] Open
Abstract
Serine/threonine-protein kinase-1 (SMG-1) belongs to the phosphatidylinositol 3‑kinase‑related kinase family. Altered expression of SMG-1 contributes to human carcinogenesis and cancer progression. The present study detected the expression levels of SMG-1 in normal and cancerous pancreatic tissues and then assessed the effects of SMG-1-knockdown in pancreatic cancer cell lines in vitro. A pancreatic cancer tissue array and pancreatic cancer cell lines were used to detect the expression levels of SMG-1 and a lentivirus expressing either SMG-1 or negative control short hairpin (sh)RNA were used to knock down the expression of SMG-1 in the pancreatic cancer cell lines. Western blot, cell proliferation, Cell Counting kit-8, Transwell tumor cell migration and invasion assays, and flow cytometric analysis of cell apoptosis with or without gemcitabine or cisplatin treatment were performed to assess the tumor cells. The protein expression of SMG-1 was higher in the pancreatic cancer tissues and cells compared with the normal tissues. sh-SMG-1 lentivirus infection significantly suppressed the expression of SMG-1 in the pancreatic cancer cell lines, resulting in the inhibition of tumor cell proliferation and increased chemosensitivity to treatment with gemcitabine and cisplatin. However, SMG-1 knockdown had no effect on pancreatic cancer cell migration or invasion capacities. The protein expression of SMG-1 was increased in the pancreatic cancer tissues and was associated with an advanced tumor stage. Knock down of the expression of SMG-1 inhibited tumor cell proliferation and induced the chemosensitivity of pancreatic cancer cells in vitro.
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Affiliation(s)
- Qingguang Wang
- Department of General Surgery, Zoucheng People's Hospital, Jining, Shandong 273500, P.R. China
| | - Dong Xu
- Department of General Surgery, Gaochun People's Hospital, Nanjing, Jiangsu 211300, P.R. China
| | - Chao Han
- Department of General Surgery, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210011, P.R. China
| | - Min Tu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Qing Du
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Jingjing Zhang
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yi Zhu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Lijian Xu
- Department of General Surgery, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210011, P.R. China
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18
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Han LL, Nan HC, Tian T, Guo H, Hu TH, Wang WJ, Ma JQ, Jiang LL, Guo QQ, Yang CC, Kang XM, Liu Y, Gao Y, Liu QL, Nan KJ. Expression and significance of the novel tumor-suppressor gene SMG-1 in hepatocellular carcinoma. Oncol Rep 2014; 31:2569-78. [PMID: 24700316 DOI: 10.3892/or.2014.3125] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 03/20/2014] [Indexed: 11/05/2022] Open
Abstract
Recent studies have demonstrated that SMG-1, a newly characterized member of the family of phosphatidylinositol 3-kinase-related protein kinases (PIKKs), is involved in tumorigenesis as a new tumor suppressor. However, its expression and significance in hepatocellular carcinoma (HCC) remain obscure. The present study investigated SMG-1 expression in HCC tissue specimens, aimed at defining the association with clinicopathological significance. Both immunohistochemistry and qRT-PCR were employed to analyze SMG-1 expression in 157 HCC and corresponding distant normal tissue specimens. The results revealed that expression of SMG-1 was significantly lower in the HCC tissue specimens than that in the distant normal tissues. Moreover, a lower expression level of SMG-1 was significantly correlated with serum α-fetoprotein level (P=0.001), poorly differentiated tumors (P=0.009) and more advanced TNM stage (P<0.001). Further study showed that SMG-1 expression was exactly associated with tumor differentiation and clinical stage in HCC. Kaplan-Meier analysis indicated that low SMG-1 expression was related to poor overall survival, and the prognostic impact of SMG-1 was further confirmed by stratified survival analysis. Importantly, multivariate analysis revealed that low SMG-1 expression was an independent prognostic marker for an unfavorable overall survival. We conclude that SMG-1 is downregulated in HCC and may represent a promising biomarker for predicting the prognosis of HCC, including the prognosis of early-stage patients.
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Affiliation(s)
- Li-Li Han
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Hao-Cheng Nan
- Department of Surgical Oncology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, P.R. China
| | - Tao Tian
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Hui Guo
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Ting-Hua Hu
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Wen-Juan Wang
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Jie-Qun Ma
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Li-Li Jiang
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Qian-Qian Guo
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Cheng-Cheng Yang
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Xiao-Min Kang
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Ying Liu
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Yuan Gao
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
| | - Qi-Lun Liu
- Department of Surgical Oncology, General Hospital of Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, P.R. China
| | - Ke-Jun Nan
- Department of Oncology, First Affiliated Hospital, College of Medicine of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
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19
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Ishigaki Y, Nakamura Y, Tatsuno T, Hashimoto M, Shimasaki T, Iwabuchi K, Tomosugi N. Depletion of RNA-binding protein RBM8A (Y14) causes cell cycle deficiency and apoptosis in human cells. Exp Biol Med (Maywood) 2014; 238:889-97. [PMID: 23970407 DOI: 10.1177/1535370213494646] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RBM8A (Y14) contains an RNA-binding motif and forms a tight heterodimer with Magoh. The heterodimer is known to be a member of the exon junction complex that forms on mRNA before export and it is required for mRNA metabolism processes such as splicing, mRNA export and nonsense-mediated mRNA decay. Recently, deficient cellular proliferation has been observed in RBM8A- or Magoh-depleted cells. These results prompted us to study the role of RBM8A in cell cycle progression of human tumour cells. The depletion of RBM8A in A549 cells resulted in poor cell survival and the accumulation of mitotic cells. After release from G1/S arrest induced by a double thymidine block, the RBM8A-silenced cells could not proceed to the next G1 phase beyond G2/M phase. Finally, the sub-G1 population increased and the apoptosis markers caspases 3/7 were activated. Silenced cells exhibited an increased frequency of multipolar or monopolar centrosomes, which may have caused the observed deficiency in cell cycle progression. Finally, silencing of either RBM8A or Magoh resulted in mutual downregulation of the other protein. These results illustrate that the RBM8A-Magoh mRNA binding complex is required for M phase progression and both proteins may be novel targets for anticancer therapy.
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Affiliation(s)
- Yasuhito Ishigaki
- Division of Advanced Medicine, Medical Research Institute, Kanazawa Medical University, Uchinada-machi, Kahoku-gun 920-0293, Japan
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Cho H, Han S, Park OH, Kim YK. SMG1 regulates adipogenesis via targeting of staufen1-mediated mRNA decay. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:1276-87. [DOI: 10.1016/j.bbagrm.2013.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 12/21/2022]
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Gubanova E, Issaeva N, Gokturk C, Djureinovic T, Helleday T. SMG-1 suppresses CDK2 and tumor growth by regulating both the p53 and Cdc25A signaling pathways. Cell Cycle 2013; 12:3770-80. [PMID: 24107632 DOI: 10.4161/cc.26660] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The DNA damage response is coordinated by phosphatidylinositol 3-kinase-related kinases, ATM, ATR, and DNA-PK. SMG-1 is the least studied stress-responsive member of this family. Here, we show that SMG-1 regulates the G 1/S checkpoint through both a p53-dependent, and a p53-independent pathway. We identify Cdc25A as a new SMG-1 substrate, and show that cells depleted of SMG-1 exhibit prolonged Cdc25A stability, failing to inactivate CDK2 in response to radiation. Given an increased tumor growth following depletion of SMG-1, our data demonstrate a novel role for SMG-1 in regulating Cdc25A and suppressing oncogenic CDK2 driven proliferation, confirming SMG-1 as a tumor suppressor.
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Affiliation(s)
- Evgenia Gubanova
- Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden; Science for Life Laboratory; Division of Translational Medicine and Chemical Biology; Department of Medical Biochemistry and Biophysics; Karolinska Institute; Stockholm, Sweden
| | - Natalia Issaeva
- Department of Surgery, Otolaryngology; Yale University; New Haven, CT USA; Cancer Center; Yale University, New Haven, CT USA
| | - Camilla Gokturk
- Science for Life Laboratory; Division of Translational Medicine and Chemical Biology; Department of Medical Biochemistry and Biophysics; Karolinska Institute; Stockholm, Sweden
| | - Tatjana Djureinovic
- Department of Molecular Biosciences; The Wenner-Gren Institute; Stockholm University; Stockholm, Sweden
| | - Thomas Helleday
- Science for Life Laboratory; Division of Translational Medicine and Chemical Biology; Department of Medical Biochemistry and Biophysics; Karolinska Institute; Stockholm, Sweden
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The C-terminal residues of Saccharomyces cerevisiae Mec1 are required for its localization, stability, and function. G3-GENES GENOMES GENETICS 2013; 3:1661-74. [PMID: 23934994 PMCID: PMC3789791 DOI: 10.1534/g3.113.006841] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mec1, a member of the phosphoinositide three-kinase-related kinase (PIKK) family of proteins, is involved in the response to replicative stress and DNA damage and in telomere maintenance. An essential 30 to 35 residue, the FATC domain is found at the C-terminus of all PIKK family members. To investigate the roles of the C-terminal residues of Mec1, we characterized alleles of Saccharomyces cerevisiae mec1 that alter the FATC domain. A change of the terminal tryptophan to alanine resulted in temperature-sensitive growth, sensitivity to hydroxyurea, and diminished kinase activity in vitro. Addition of a terminal glycine or deletion of one, two, or three residues resulted in loss of cell viability and kinase function. Each of these Mec1 derivatives was less stable than wild-type Mec1, eluted abnormally from a size exclusion column, and showed reduced nuclear localization. We identified rpn3-L140P, which encodes a component of the 19S proteasomal regulatory particle of the 26S proteasome, as a suppressor of the temperature-sensitive growth caused by mec1-W2368A. The rpn3-L140P allele acted in a partially dominant fashion. It was not able to suppress the inviability of the C-terminal truncations or additions or the hydroxyurea sensitivity of mec1-W2368A. The rpn3-L140P allele restored Mec1-W2368A to nearly wild-type protein levels at 37°, an effect partially mimicked by the proteasome inhibitor MG-132. Our study supports a role for the C-terminus in Mec1 folding and stability, and suggests a role for the proteasome in regulating Mec1 levels.
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Abnormal mitosis triggers p53-dependent cell cycle arrest in human tetraploid cells. Chromosoma 2013; 122:305-18. [DOI: 10.1007/s00412-013-0414-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 04/09/2013] [Accepted: 04/09/2013] [Indexed: 10/26/2022]
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Huang L, Wilkinson MF. Regulation of nonsense-mediated mRNA decay. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:807-28. [PMID: 23027648 DOI: 10.1002/wrna.1137] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is a highly conserved pathway that was originally identified as a RNA surveillance mechanism that degrades aberrant mRNAs harboring premature termination (nonsense) codons. Recently, it was discovered that NMD also regulates normal gene expression. Genome-wide studies showed that ablation of NMD alters the expression of ∼10% of transcripts in a wide variety of eukaryotes. In general, NMD specifically targets normal transcripts that harbor a stop codon in a premature context. The finding that NMD regulates normal gene expression raises the possibility that NMD itself is subject to regulation. Indeed, recent studies have shown that NMD efficiency varies in different cell types and tissues. NMD is also subject to developmental control in both higher and lower eukaryotic species. Molecular mechanisms have been defined-including those involving microRNAs and other RNA decay pathways-that regulate the magnitude of NMD in some developmental settings. This developmental regulation of NMD appears to have physiological roles, at least in some model systems. In addition to mechanisms that modulate the efficiency of NMD, mechanisms have recently been identified that serve the opposite purpose: to maintain the efficiency of NMD in the face of insults. This 'buffering' is achieved by feedback networks that serve to regulate the stability of NMD factors. The discovery of NMD homeostasis and NMD regulatory mechanisms has important implications for how NMD acts in biological processes and how its magnitude could potentially be manipulated for clinical benefit.
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Affiliation(s)
- Lulu Huang
- Department of Reproductive Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA
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Blickwedehl J, Olejniczak S, Cummings R, Sarvaiya N, Mantilla A, Chanan-Khan A, Pandita TK, Schmidt M, Thompson CB, Bangia N. The proteasome activator PA200 regulates tumor cell responsiveness to glutamine and resistance to ionizing radiation. Mol Cancer Res 2012; 10:937-44. [PMID: 22550082 DOI: 10.1158/1541-7786.mcr-11-0493-t] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The cellular response to ionizing radiation (IR) involves a variety of mechanisms to repair damage and maintain cell survival. We previously reported that the proteasome activator PA200 promotes long-term cell survival after IR exposure. The molecular function of PA200 is to enhance proteasome-mediated cleavage after glutamate; however, it is not known how this molecular function promotes survival after IR exposure. Here, we report that upon IR exposure, cellular demand for exogenous glutamine is increased. Cells containing PA200 are capable of surviving this IR-induced glutamine demand, whereas PA200-deficient cells show impaired long-term survival. Additional glutamine supplementation reverses the radiosensitivity of PA200-knockdown cells suggesting impaired glutamine homeostasis in these cells. Indeed, PA200-knockdown cells are unable to maintain intracellular glutamine levels. Furthermore, when extracellular glutamine is limiting, cells that contain PA200 respond by slowing growth, but PA200-knockdown cells and cells in which post-glutamyl proteasome activity is inhibited are nonresponsive and continue rapid growth. This cellular unresponsiveness to nutrient depletion is also reflected at the level of the mTOR substrate ribosomal S6 kinase (S6K). Thus, inability to restrict growth causes PA200-deficient cells to continue growing and eventually die due to lack of available glutamine. Together, these data indicate an important role for PA200 and post-glutamyl proteasome activity in maintaining glutamine homeostasis, which appears to be especially important for long-term survival of tumor cells after radiation exposure.
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González-Estévez C, Felix DA, Smith MD, Paps J, Morley SJ, James V, Sharp TV, Aboobaker AA. SMG-1 and mTORC1 act antagonistically to regulate response to injury and growth in planarians. PLoS Genet 2012; 8:e1002619. [PMID: 22479207 PMCID: PMC3315482 DOI: 10.1371/journal.pgen.1002619] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 02/08/2012] [Indexed: 12/31/2022] Open
Abstract
Planarian flatworms are able to both regenerate their whole bodies and continuously adapt their size to nutrient status. Tight control of stem cell proliferation and differentiation during these processes is the key feature of planarian biology. Here we show that the planarian homolog of the phosphoinositide 3-kinase-related kinase (PIKK) family member SMG-1 and mTOR complex 1 components are required for this tight control. Loss of smg-1 results in a hyper-responsiveness to injury and growth and the formation of regenerative blastemas that remain undifferentiated and that lead to lethal ectopic outgrowths. Invasive stem cell hyper-proliferation, hyperplasia, hypertrophy, and differentiation defects are hallmarks of this uncontrolled growth. These data imply a previously unappreciated and novel physiological function for this PIKK family member. In contrast we found that planarian members of the mTOR complex 1, tor and raptor, are required for the initial response to injury and blastema formation. Double smg-1 RNAi experiments with tor or raptor show that abnormal growth requires mTOR signalling. We also found that the macrolide rapamycin, a natural compound inhibitor of mTORC1, is able to increase the survival rate of smg-1 RNAi animals by decreasing cell proliferation. Our findings support a model where Smg-1 acts as a novel regulator of both the response to injury and growth control mechanisms. Our data suggest the possibility that this may be by suppressing mTOR signalling. Characterisation of both the planarian mTORC1 signalling components and another PIKK family member as key regulators of regeneration and growth will influence future work on regeneration, growth control, and the development of anti-cancer therapies that target mTOR signalling. Planarian flatworms have a remarkable ability to regenerate that has driven the curiosity of scientists for more than a century. They are also able to continuously grow or degrow their bodies, depending on food availability. Around 25% of the cells in the planarian body are adult stem cells, which are responsible for this incredible plasticity. The initial response of planarians to injury is characterised by a rapid increase in stem cell division. Subsequently planarians form a specialised new tissue called the regenerative blastema to replace missing tissues. Currently, very little is known about the molecular signals controlling the response to injury or the tight regulation of growth. Here we discovered that a gene called Smg-1 and the conserved mTOR signalling pathway, a central regulator of animal growth, are both regulators of this process. SMG-1 is required to limit and act as a brake on the initial response to injury and ensure that it does not run out of control, while in contrast mTOR signalling is required to drive this process forward. Loss of SMG-1 leads to hyperactive responses to injury and subsequent growth that continues out of control. Eventually, these animals form outgrowths, which display several hallmarks of human cancers. These opposing roles suggested that Smg-1 phenotype would require mTOR signalling, and by reducing mTOR signalling and SMG-1 activity at the same time we found that this was the case. We conclude that Smg-1 is a novel regulator of regeneration and animal growth with an antagonistic role to mTOR signalling in planarians.
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Affiliation(s)
- Cristina González-Estévez
- Centre for Genetics and Genomics, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
- * E-mail: (AAA); (CG-E)
| | - Daniel A. Felix
- Centre for Genetics and Genomics, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
| | - Matthew D. Smith
- Centre for Genetics and Genomics, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
| | - Jordi Paps
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Simon J. Morley
- Department of Biochemistry, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Victoria James
- School of Biomedical Sciences, University of Nottingham Medical School, Nottingham, United Kingdom
| | - Tyson V. Sharp
- School of Biomedical Sciences, University of Nottingham Medical School, Nottingham, United Kingdom
| | - A. Aziz Aboobaker
- Centre for Genetics and Genomics, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom
- * E-mail: (AAA); (CG-E)
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Abstract
hSMG-1 is a member of the phosphoinositide 3 kinase-like kinase (PIKK) family with established roles in nonsense-mediated decay (NMD) of mRNA containing premature termination codons and in genotoxic stress responses to DNA damage. We report here a novel role for hSMG-1 in cytoplasmic stress granule (SG) formation. Exposure of cells to stress causing agents led to the localization of hSMG-1 to SG, identified by colocalization with TIA-1, G3BP1, and eIF4G. hSMG-1 small interfering RNA and the PIKK inhibitor wortmannin prevented formation of a subset of SG, while specific inhibitors of ATM, DNA-PK(cs), or mTOR had no effect. Exposure of cells to H(2)O(2) and sodium arsenite induced (S/T)Q phosphorylation of proteins. While Upf2 and Upf1, an essential substrate for hSMG-1 in NMD, were present in SG, NMD-specific Upf1 phosphorylation was not detected in SG, indicating hSMG-1's role in SG is separate from classical NMD. Thus, SG formation appears more complex than originally envisaged and hSMG-1 plays a central role in this process.
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28
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Gewandter JS, Bambara RA, O'Reilly MA. The RNA surveillance protein SMG1 activates p53 in response to DNA double-strand breaks but not exogenously oxidized mRNA. Cell Cycle 2011; 10:2561-7. [PMID: 21701263 DOI: 10.4161/cc.10.15.16347] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
DNA damage, stalled replication forks, errors in mRNA splicing, and availability of nutrients activate specific phosphatidylinositiol-3 kinase-like kinases (PIKKs) that in turn phosphorylate downstream targets such as p53 on serine 15. While the PIKK proteins ATM and ATR respond to specific DNA lesions, SMG1 responds to errors in mRNA splicing and when cells are exposed to genotoxic stress. Yet, whether genotoxic stress activates SMG1 through specific types of DNA lesions or RNA damage remains poorly understood. Here, we demonstrate that siRNA oligonucleotides targeting the mRNA surveillance proteins SMG1, Upf1, Upf2, or the PIKK protein ATM attenuated p53 (ser15) phosphorylation in cells damaged by high oxygen (hyperoxia), a model of persistent oxidative stress that damages nucleotides. In contrast, loss of SMG1 or ATM, but not Upf1 or Upf2 reduced p53 (ser15) phosphorylation in response to DNA double strand breaks produced by expression of the endonuclease I-PpoI. To determine whether SMG1-dependent activation of p53 was in response to oxidative mRNA damage, mRNA encoding green fluorescence protein (GFP) transcribed in vitro was oxidized by Fenton chemistry and transfected into cells. Although oxidation of GFP mRNA resulted in dose-dependent fragmentation of the mRNA and reduced expression of GFP, it did not stimulate p53 or the p53-target gene p21. These findings establish SMG1 activates p53 in response to DNA double-strand breaks independent of the RNA surveillance proteins Upf1 or Upf2; however, these proteins can stimulate p53 in response to oxidative stress but not necessarily oxidized RNA.
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Affiliation(s)
- Jennifer S Gewandter
- Department of Biochemistry and Biophysics, The University of Rochester, Rochester, NY, USA
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29
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Semlitsch M, Shackelford RE, Zirkl S, Sattler W, Malle E. ATM protects against oxidative stress induced by oxidized low-density lipoprotein. DNA Repair (Amst) 2011; 10:848-60. [PMID: 21669554 PMCID: PMC3154283 DOI: 10.1016/j.dnarep.2011.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 04/15/2011] [Accepted: 05/10/2011] [Indexed: 11/29/2022]
Abstract
Chronic oxidative stress is involved in the pathogenesis of multiple inflammatory diseases, including cardiovascular disease and atherosclerosis. The rare autosomal recessive disorder Ataxia-telangiectasia (A-T) is characterized by progressive cerebellar ataxia secondary to Purkinje cell death, immunodeficiency, and increased cancer incidence. ATM, the protein mutated in A-T, plays a key role in cellular DNA-damage responses. A-T cells show poor cellular anti-oxidant defences and increased oxidant sensitivity compared to normal cells, and ATM functions, in part, as an oxidative stress sensor. The oxidation of low-density lipoprotein (oxLDL) and its uptake by macrophages is an initiating step in the development of atherosclerosis. We demonstrate that oxLDL activates ATM and downstream p21 expression in normal fibroblasts and endothelial cells. In ATM-deficient fibroblasts oxLDL induces DNA double-strand breaks, micronuclei formation and causes chromosome breaks. Furthermore, oxLDL decreases cell viability and inhibits colony formation in A-T fibroblasts more effectively as compared to normal controls. Formation of oxLDL-induced reactive oxygen species is significantly higher in A-T, than normal fibroblasts. Last, pre-treatment of cells with ammonium pyrrolidine dithiocarbamate, a potent antioxidant and inhibitor of transcription factor nuclear factor κB, reduces oxLDL-induced reactive oxygen species formation. Our data indicates that ATM functions in the defence against oxLDL-mediated cytotoxicity.
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Affiliation(s)
- Michaela Semlitsch
- Institute of Molecular Biology and Biochemistry, Center for Molecular Medicine, Medical University of Graz, Harrachgasse 21, A-8010 Graz, Austria
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30
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Isken O, Maquat LE. The multiple lives of NMD factors: balancing roles in gene and genome regulation. Nat Rev Genet 2011; 9:699-712. [PMID: 18679436 DOI: 10.1038/nrg2402] [Citation(s) in RCA: 238] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) largely functions to ensure the quality of gene expression. However, NMD is also crucial to regulating appropriate expression levels for certain genes and for maintaining genome stability. Furthermore, just as NMD serves cells in multiple ways, so do its constituent proteins. Recent studies have clarified that UPF and SMG proteins, which were originally discovered to function in NMD, also have roles in other pathways, including specialized pathways of mRNA decay, DNA synthesis and cell-cycle progression, and the maintenance of telomeres. These findings suggest a delicate balance of metabolic events - some not obviously related to NMD - that can be influenced by the cellular abundance, location and activity of NMD factors and their binding partners.
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Affiliation(s)
- Olaf Isken
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, New York 14642, USA
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31
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Cheung HH, St Jean M, Beug ST, Lejmi-Mrad R, LaCasse E, Baird SD, Stojdl DF, Screaton RA, Korneluk RG. SMG1 and NIK regulate apoptosis induced by Smac mimetic compounds. Cell Death Dis 2011; 2:e146. [PMID: 21490678 PMCID: PMC3122057 DOI: 10.1038/cddis.2011.25] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 02/23/2011] [Accepted: 03/01/2011] [Indexed: 12/30/2022]
Abstract
Smac mimetic compounds (SMCs) are experimental small molecules that induce tumour necrosis factor alpha (TNFα)-dependent cancer cell death by targeting the inhibitor of apoptosis proteins. However, many cancer cell lines are resistant to SMC-mediated apoptosis despite the presence of TNFα. To add insight into the mechanism of SMC-resistance, we used functional siRNA-based kinomic and focused chemical screens and identified suppressor of morphogenesis in genitalia-1 (SMG1) and NF-κB-inducing kinase (NIK) as novel protective factors. Both SMG1 and NIK prevent SMC-mediated apoptosis likely by maintaining FLICE inhibitory protein (c-FLIP) levels to suppress caspase-8 activation. In SMC-resistant cells, the accumulation of NIK upon SMC treatment enhanced the activity of both the classical and alternative nuclear factor-κB pathways, and increased c-FLIP mRNA levels. In parallel, persistent SMG1 expression in SMC-resistant cells repressed SMC-mediated TNFα-induced JNK activation and c-FLIP levels were sustained. Importantly, SMC-resistance is overcome by depleting NIK and SMG1, which appear to facilitate the downregulation of c-FLIP in response to SMC and TNFα treatment, leading to caspase-8-dependent apoptosis. Collectively, these data show that SMG1 and NIK function as critical repressors of SMC-mediated apoptosis by potentially converging on the regulation of c-FLIP metabolism.
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Affiliation(s)
- H H Cheung
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - M St Jean
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - S T Beug
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - R Lejmi-Mrad
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - E LaCasse
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - S D Baird
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
| | - D F Stojdl
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - R A Screaton
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - R G Korneluk
- Apoptosis Research Centre, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario K1H 8L1, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
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32
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hSMG-1 is a granzyme B-associated stress-responsive protein kinase. J Mol Med (Berl) 2011; 89:411-21. [DOI: 10.1007/s00109-010-0708-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 11/24/2010] [Accepted: 11/25/2010] [Indexed: 10/18/2022]
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Human SMG-1 is involved in gemcitabine-induced primary microRNA-155/BIC up-regulation in human pancreatic cancer PANC-1 cells. Pancreas 2011; 40:55-60. [PMID: 20871480 DOI: 10.1097/mpa.0b013e3181e89f74] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES Human primary microRNA-155/B-cell integration cluster (BIC) transcript is the precursor of microRNA-155. The overexpression of them has been widely observed in the progression of various types of tumors. Our objective was to investigate the effect of anticancer agents on the expression of BIC and possible signal pathways that involved in. METHODS Quantitative real-time reverse transcriptase polymerase chain reaction was used to measure the expression of BIC. Chemical inhibitors against c-Jun N-terminal kinase 1, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2, protein kinase C, checkpoint kinase 1, and phosphatidylinositol 3 kinase (PI3K) were used for the evaluation of involved signal pathways. RNA interference was used to knock down the expression of ataxia-telangiectasia mutated, ataxia-telangiectasia and Rad3 related, and suppressor of morphogenesis in genitalia-1 (SMG-1), and Western blot was carried out to evaluate the knockdown effect. RESULTS B-cell integration cluster expression was induced by a representative anti-pancreatic cancer drug, gemcitabine, in human pancreatic cancer PANC-1 cells. The mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 and c-Jun N-terminal kinase inhibitors, but not the checkpoint kinase 1 and protein kinase C inhibitors, suppressed the up-regulation of BIC. B-cell integration cluster up-regulation was also significantly inhibited by the PI3K inhibitor wortmannin. RNA interference studies showed that wortmannin-sensitive SMG-1 but not ataxia-telangiectasia mutated or ataxia-telangiectasia and Rad3 related was involved in the up-regulation. CONCLUSIONS Our results show that multiple pathways can be involved in the up-regulation of BIC. Furthermore, we demonstrate for the first time that PI3K SMG-1 is required for gemcitabine-induced up-regulation of BIC transcript.
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Wu YCM, O'Reilly MA. Bcl-X(L) is the primary mediator of p21 protection against hyperoxia-induced cell death. Exp Lung Res 2010; 37:82-91. [PMID: 21128858 DOI: 10.3109/01902148.2010.521617] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A tight balance between anti- and proapoptotic members of the Bcl-2 family controls cell survival and death. Exposure to hyperoxia shifts this balance towards a prodeath state that ultimately activates Bak- and Bax-dependent cell death. Mechanisms underlying this shift are undefined; however, the cell cycle inhibitor p21 delays the loss of antiapoptotic Mcl-1 and Bcl-X(L), and protects against hyperoxia. Here, H1299 human lung adenocarcinoma cells are used to investigate how these and other members of the Bcl-2 family cooperate with p21 to protect against hyperoxia. Expression of antiapoptotic Mcl-1 and Bcl-X(L), but not Bcl-2 or A1, declined during hyperoxia, whereas proapoptotic Bak, but not Bax, increased. Conditional overexpression of p21 selectively delayed the loss of Mcl-1 and Bcl-X(L), without affecting expression of the other members. siRNA knockdown of Mcl-1 and Bcl-X(L) sensitized cells to hyperoxia, but only the loss of Bcl-X(L) ablated the protective effects of p21. Conversely, overexpression of Mcl-1 and Bcl-X(L) protected against hyperoxia, but only Bcl-X(L) bound Bak and Bax. Altogether, these data suggest that Bcl-X(L) is the primary mediator by which p21 protects against hyperoxia-induced Bak/Bax-dependent cell death.
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Affiliation(s)
- Yu-Chieh M Wu
- Department of Biomedical Genetics, School of Medicine and Dentistry, The University of Rochester, Rochester, New York 14642, USA
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Kurokawa K, Kuwano Y, Tominaga K, Kawai T, Katsuura S, Yamagishi N, Satake Y, Kajita K, Tanahashi T, Rokutan K. Brief naturalistic stress induces an alternative splice variant of SMG-1 lacking exon 63 in peripheral leukocytes. Neurosci Lett 2010; 484:128-32. [DOI: 10.1016/j.neulet.2010.08.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 08/08/2010] [Accepted: 08/10/2010] [Indexed: 11/26/2022]
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Fernández IS, Yamashita A, Arias-Palomo E, Bamba Y, Bartolomé RA, Canales MA, Teixidó J, Ohno S, Llorca O. Characterization of SMG-9, an essential component of the nonsense-mediated mRNA decay SMG1C complex. Nucleic Acids Res 2010; 39:347-58. [PMID: 20817927 PMCID: PMC3017601 DOI: 10.1093/nar/gkq749] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
SMG-9 is part of a protein kinase complex, SMG1C, which consists of the SMG-1 kinase, SMG-8 and SMG-9. SMG1C mediated phosphorylation of Upf1 triggers nonsense-mediated mRNA decay (NMD), a eukaryotic surveillance pathway that detects and targets for degradation mRNAs harboring premature translation termination codons. Here, we have characterized SMG-9, showing that it comprises an N-terminal 180 residue intrinsically disordered region (IDR) followed by a well-folded C-terminal domain. Both domains are required for SMG-1 binding and the integrity of the SMG1C complex, whereas the C-terminus is sufficient to interact with SMG-8. In addition, we have found that SMG-9 assembles in vivo into SMG-9:SMG-9 and, most likely, SMG-8:SMG-9 complexes that are not constituents of SMG1C. SMG-9 self-association is driven by interactions between the C-terminal domains and surprisingly, some SMG-9 oligomers are completely devoid of SMG-1 and SMG-8. We propose that SMG-9 has biological functions beyond SMG1C, as part of distinct SMG-9-containing complexes. Some of these complexes may function as intermediates potentially regulating SMG1C assembly, tuning the activity of SMG-1 with the NMD machinery. The structural malleability of IDRs could facilitate the transit of SMG-9 through several macromolecular complexes.
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Affiliation(s)
- Israel S Fernández
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), Ramiro de Maetzu 9, 28040 Madrid, Spain
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Nicholson P, Yepiskoposyan H, Metze S, Zamudio Orozco R, Kleinschmidt N, Mühlemann O. Nonsense-mediated mRNA decay in human cells: mechanistic insights, functions beyond quality control and the double-life of NMD factors. Cell Mol Life Sci 2010; 67:677-700. [PMID: 19859661 PMCID: PMC11115722 DOI: 10.1007/s00018-009-0177-1] [Citation(s) in RCA: 254] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 09/16/2009] [Accepted: 10/06/2009] [Indexed: 12/16/2022]
Abstract
Nonsense-mediated decay is well known by the lucid definition of being a RNA surveillance mechanism that ensures the speedy degradation of mRNAs containing premature translation termination codons. However, as we review here, NMD is far from being a simple quality control mechanism; it also regulates the stability of many wild-type transcripts. We summarise the abundance of research that has characterised each of the NMD factors and present a unified model for the recognition of NMD substrates. The contentious issue of how and where NMD occurs is also discussed, particularly with regard to P-bodies and SMG6-driven endonucleolytic degradation. In recent years, the discovery of additional functions played by several of the NMD factors has further complicated the picture. Therefore, we also review the reported roles of UPF1, SMG1 and SMG6 in other cellular processes.
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Affiliation(s)
- Pamela Nicholson
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Hasmik Yepiskoposyan
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Stefanie Metze
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Rodolfo Zamudio Orozco
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Nicole Kleinschmidt
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
| | - Oliver Mühlemann
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, 3012, Bern, Switzerland
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Staversky RJ, Vitiello PF, Yee M, Callahan LM, Dean DA, O'Reilly MA. Epithelial ablation of Bcl-XL increases sensitivity to oxygen without disrupting lung development. Am J Respir Cell Mol Biol 2009; 43:376-85. [PMID: 19880821 DOI: 10.1165/rcmb.2009-0165oc] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Recent studies indicate that the antiapoptotic Bcl-X(L), one of five isoforms expressed by the Bcl-X gene, protects a variety of cell lines exposed to hyperoxia. However, its role in lung development and protection against oxidative stress in vivo is not known. Here, we show Bcl-X(L) is the predominant isoform expressed in the lung, and the only isoform detected in respiratory epithelium. Because loss of Bcl-X(L) is embryonically lethal, Bcl-X(L) was ablated throughout the respiratory epithelium by mating mice with a floxed exon II of the Bcl-X gene with mice expressing Cre under control of the surfactant protein-C promoter. Interestingly, the loss of Bcl-X(L) in respiratory epithelium was perinatally lethal in approximately 50% of the expected offspring. However, some adult mice lacking the gene were obtained. The epithelial-specific ablation of Bcl-X(L) did not disrupt pulmonary function, the expression of epithelial cell-specific markers, or lung development. However, it shifted the lung toward a proapoptotic state, defined by a reduction in antiapoptotic Mcl-1, an increase in proapoptotic Bak, and increased sensitivity of the respiratory epithelium to hyperoxia. Intriguingly, increased 8-oxoguanine lesions seen during hyperoxia were also evident as lungs transitioned to room air at birth, a time when perinatal lethality in some mice lacking Bcl-X(L) was observed. These findings reveal that the epithelial-specific expression of Bcl-X(L) is not required for proper lung development, but functions to protect respiratory epithelial cells against oxygen-induced toxicity, such as during hyperoxia and the lung's first exposure to ambient air.
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Yamashita A, Izumi N, Kashima I, Ohnishi T, Saari B, Katsuhata Y, Muramatsu R, Morita T, Iwamatsu A, Hachiya T, Kurata R, Hirano H, Anderson P, Ohno S. SMG-8 and SMG-9, two novel subunits of the SMG-1 complex, regulate remodeling of the mRNA surveillance complex during nonsense-mediated mRNA decay. Genes Dev 2009; 23:1091-105. [PMID: 19417104 DOI: 10.1101/gad.1767209] [Citation(s) in RCA: 197] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism that detects and degrades mRNAs containing premature translation termination codons (PTCs). SMG-1 and Upf1 transiently form a surveillance complex termed "SURF" that includes eRF1 and eRF3 on post-spliced mRNAs during recognition of PTC. If an exon junction complex (EJC) exists downstream from the SURF complex, SMG-1 phosphorylates Upf1, the step that is a rate-limiting for NMD. We provide evidence of an association between the SURF complex and the ribosome in association with mRNPs, and we suggest that the SURF complex functions as a translation termination complex during NMD. We identified SMG-8 and SMG-9 as novel subunits of the SMG-1 complex. SMG-8 and SMG-9 suppress SMG-1 kinase activity in the isolated SMG-1 complex and are involved in NMD in both mammals and nematodes. SMG-8 recruits SMG-1 to the mRNA surveillance complex, and inactivation of SMG-8 induces accumulation of a ribosome:Upf1:eRF1:eRF3:EJC complex on mRNP, which physically bridges the ribosome and EJC through eRF1, eRF3, and Upf1. These results not only reveal the regulatory mechanism of SMG-1 kinase but also reveal the sequential remodeling of the ribosome:SURF complex to the predicted DECID (DECay InDucing) complex, a ribosome:SURF:EJC complex, as a mechanism of in vivo PTC discrimination.
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Affiliation(s)
- Akio Yamashita
- Department of Molecular Biology, Yokohama City University School of Medicine, Yokohama, Japan.
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Chen RQ, Yang QK, Chen YL, Oliveira VA, Dalton WS, Fearns C, Lee JD. Kinome siRNA screen identifies SMG-1 as a negative regulator of hypoxia-inducible factor-1alpha in hypoxia. J Biol Chem 2009; 284:16752-16758. [PMID: 19406746 PMCID: PMC2719310 DOI: 10.1074/jbc.m109.014316] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hypoxia-inducible factor-1 (HIF-1) plays a central role in tumor progression by regulating genes involved in proliferation, glycolysis, angiogenesis, and metastasis. To improve our understanding of HIF-1 regulation by kinome, we screened a kinase-specific small interference RNA library using a hypoxia-response element (HRE) luciferase reporter assay under hypoxic conditions. This screen determined that depletion of cellular SMG-1 kinase most significantly modified cellular HIF-1 activity in hypoxia. SMG-1 is the newest and least studied member of the phosphoinositide 3-kinase-related kinase family, which consists of ATM, ATR, DNA-PKcs, mTOR, and SMG-1. We individually depleted members of the phosphoinositide 3-kinase-related kinase family, and only SMG-1 deficiency significantly augmented HIF-1 activity in hypoxia. We subsequently discovered that SMG-1 kinase activity was activated by hypoxia, and depletion of SMG-1 up-regulated MAPK activity under low oxygen. Suppressing cellular MAPK by silencing ERK1/2 or by treatment with U0126, a MAPK inhibitor, partially blocked the escalation of HIF-1 activity resulting from SMG-1 deficiency in hypoxic cells. Increased expression of SMG-1 but not kinase-dead SMG-1 effectively inhibited the activity of HIF-1alpha. In addition, cellular SMG-1 deficiency increased secretion of the HIF-1alpha-regulated angiogenic factor, vascular epidermal growth factor, and survival factor, carbonic anhydrase IX (CA9), as well as promoted the hypoxic cell motility. Taken together, we discovered that SMG-1 negatively regulated HIF-1alpha activity in hypoxia, in part through blocking MAPK activation.
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Affiliation(s)
- Run-Qiang Chen
- From the Departments of Immunology and Microbial Science, La Jolla, California 92037
| | - Qing-Kai Yang
- From the Departments of Immunology and Microbial Science, La Jolla, California 92037
| | - Yan-Ling Chen
- From the Departments of Immunology and Microbial Science, La Jolla, California 92037
| | - Vasco A Oliveira
- Chemistry, The Scripps Research Institute, La Jolla, California 92037
| | - William S Dalton
- Chemistry, The Scripps Research Institute, La Jolla, California 92037
| | - Colleen Fearns
- Department of Experimental Therapeutics and Interdisciplinary Oncology, H. Lee Moffitt Cancer Center & Research Institute, University of South Florida, Tampa, Florida 33612
| | - Jiing-Dwan Lee
- From the Departments of Immunology and Microbial Science, La Jolla, California 92037.
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Leemput J, Masson C, Bigot K, Errachid A, Dansault A, Provost A, Gadin S, Aoufouchi S, Menasche M, Abitbol M. ATM localization and gene expression in the adult mouse eye. Mol Vis 2009; 15:393-416. [PMID: 19234633 PMCID: PMC2645907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 02/14/2009] [Indexed: 11/19/2022] Open
Abstract
PURPOSE High levels of metabolism and oxygen consumption in most adult murine ocular compartments, combined with exposure to light and ultraviolet (UV) radiation, are major sources of oxidative stress, causing DNA damage in ocular cells. Of all mammalian body cells, photoreceptor cells consume the largest amount of oxygen and generate the highest levels of oxidative damage. The accumulation of such damage throughout life is a major factor of aging tissues. Several multiprotein complexes have recently been identified as the major sensors and mediators involved in the maintenance of DNA integrity. The activity of these complexes initially seemed to be restricted to dividing cells, given their ultimate role in major cell cycle checkpoints. However, it was later established that they are also active in post-mitotic cells. Recent findings demonstrate that the DNA damage response (DDR) is essential for the development, maintenance, and normal functioning of the adult central nervous system. One major molecular factor in the DDR is the protein, ataxia telangiectasia mutated (ATM). It is required for the rapid induction of cellular responses to DNA double-strand breaks. These cytotoxic DNA lesions may be caused by oxidative damage. To understand how ATM prevents oxidative stress and participates in the maintenance of genomic integrity and cell viability of the adult retina, we determined the ATM expression patterns and studied its localization in the adult mouse eye. METHODS Atm gene expression was analyzed by RT-PCR experiments and its localization by in situ hybridization on adult mouse ocular and cerebellar tissue sections. ATM protein expression was determined by western blot analysis of proteins homogenates extracted from several mouse tissues and its localization by immunohistochemistry experiments performed on adult mouse ocular and cerebellar tissue sections. In addition, subcellular localization was realized by confocal microscopy imaging of ocular tissue sections, with a special focus on retinal cells. RESULTS Using RT-PCR, we detected a band of the expected size, with its sequence matching the amplified Atm cDNA sequence. Atm mRNA was detected in most cell bodies of the adult mouse eye by in situ hybridization of ocular tissue sections with specific digoxigenin-labeled PCR-amplified cDNA probes. Western blotting with different specific antibodies revealed bands corresponding to the expected sizes of ATM and its active forms (ATMp). These bands were not observed in the analysis of protein homogenates from Atm-deficient mouse tissues. ATM immunoreactivity was detected in the nucleus of all adult mice retinal cells and in most non-neuronal ocular cell types. The active phosphorylated form of ATM was also present in the retina as well as in non-neuronal cells of the adult mouse eye. However, its subcellular localization differed as a function of the cell type examined. A major finding of this study was that ATMp immunostaining in photoreceptor cells was exclusively in the cytoplasm, whereas ATM immunostaining was only in the nucleus of these cells. Furthermore, the specific and distinct ATM and ATMp immunolabeling patterns in photoreceptor cells were identical to those observed in the adult mouse cerebellar granule cells. CONCLUSIONS We report the expression profile of Atm gene and protein in the adult mouse eye. In particular, we observed a difference between the localization patterns of the active and inactive forms of ATM in photoreceptor cells. These localization patterns suggest that ATM and its phosphorylated activated form may be involved in both the protection of cells from oxidative damage and the maintenance of ocular cell structure and function. The protection mechanisms mediated by the two forms of ATM appear to be particularly important in maintaining photoreceptor integrity.
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Affiliation(s)
- Julia Leemput
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Christel Masson
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Karine Bigot
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Abdelmounaim Errachid
- Université Paris-Descartes, Plateforme d’imagerie Cellulaire de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Anouk Dansault
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Alexandra Provost
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Stéphanie Gadin
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Said Aoufouchi
- Université Paris-Descartes, Développement du Système Immunitaire, INSERM U783, Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Maurice Menasche
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
| | - Marc Abitbol
- Université Paris-Descartes, CERTO, Centre de Recherche Thérapeutique en Ophtalmologie de la Faculté de Médecine Paris-Descartes-site Necker, Paris, France
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Derheimer FA, Hicks JK, Paulsen MT, Canman CE, Ljungman M. Psoralen-induced DNA interstrand cross-links block transcription and induce p53 in an ataxia-telangiectasia and rad3-related-dependent manner. Mol Pharmacol 2008; 75:599-607. [PMID: 19064630 DOI: 10.1124/mol.108.051698] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Psoralen plus UVA light (PUVA) is commonly used to treat psoriasis, a common skin disorder associated with rapid proliferation of cells. PUVA exerts its antiproliferative activity through formation of DNA monoadducts and interstrand cross-links (ICLs). However, this treatment may lead to skin malignancies as a direct result of inducing carcinogenic DNA damage. Inactivation of the p53 tumor suppressor gene is an important event in the development of skin cancer. p53 is rapidly phosphorylated and stabilized in response to DNA damage, and the induction of apoptosis by p53 is an important mechanism by which p53 exerts its tumor-suppressive activity. To better understand the mechanism by which PUVA treatment induces p53, we exposed human skin fibroblasts with PUVA under conditions that differentially produce monoadducts and ICLs and found that psoralen-induced ICLs induced phosphorylation of the Ser-15 site of p53 and apoptosis much more effectively than psoralen-induced monoadducts. The induction of p53 phosphorylation by psoralen ICLs did not require factors believed to be involved in the repair of psoralen ICLs [xeroderma pigmentosum (XP)-A, XP-C, XP-F, Cockayne's syndrome-B, Fanconi anemia] but did require the ataxia-telangiectasia and Rad3-related but not the ataxia-telangiectasia mutated kinase. Psoralen-induced ICLs blocked transcription and replication more efficiently than monoadducts, and induction of p53 and apoptosis correlated with doses causing interference with transcription rather than DNA replication. Our finding that cells underwent apoptosis preferentially during S-phase suggests that the combined blockade of transcription and DNA replication by psoralen ICLs during S-phase elicits a strong apoptotic response.
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Affiliation(s)
- Frederick A Derheimer
- Department of Radiation Oncology, Division of Radiation and Cancer Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Masse I, Molin L, Mouchiroud L, Vanhems P, Palladino F, Billaud M, Solari F. A novel role for the SMG-1 kinase in lifespan and oxidative stress resistance in Caenorhabditis elegans. PLoS One 2008; 3:e3354. [PMID: 18836529 PMCID: PMC2556085 DOI: 10.1371/journal.pone.0003354] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Accepted: 08/22/2008] [Indexed: 11/18/2022] Open
Abstract
The PTEN tumour suppressor encodes a phosphatase, and its daf-18 orthologue in Caenorhabditis elegans negatively regulates the insulin/IGF-1 DAF-2 receptor pathway that influences lifespan in worms and other species. In order to identify new DAF-18 regulated pathways involved in aging, we initiated a candidate RNAi feeding screen for clones that lengthen lifespan. Here, we report that smg-1 inactivation increases average lifespan in a daf-18 dependent manner. Genetic analysis is consistent with SMG-1 acting at least in part in parallel to the canonical DAF-2 receptor pathway, but converging on the transcription factor DAF-16/FOXO. SMG-1 is a serine-threonine kinase which plays a conserved role in nonsense-mediated mRNA decay (NMD) in worms and mammals. In addition, human SMG-1 has also been implicated in the p53-mediated response to genotoxic stress. The effect of smg-1 inactivation on lifespan appears to be unrelated to its NMD function, but requires the p53 tumour suppressor orthologue cep-1. Furthermore, smg-1 inactivation confers a resistance to oxidative stress in a daf-18-, daf-16- and cep-1-dependent manner. We propose that the role of SMG-1 in lifespan regulation is at least partly dependent on its function in oxidative stress resistance. Taken together, our results unveil a novel role for SMG-1 in lifespan regulation.
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Affiliation(s)
- Ingrid Masse
- Laboratoire de Génétique, Signalisation et Cancer, Université Claude Bernard Lyon 1, CNRS UMR5201 Domaine Rockefeller, Lyon, France
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