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Yang N, Zhang Q, Wang Q, Zhang Y, Li S, Zhao Y, Shi X, Li Q, Xu X. Nsp10-interacting host protein SAP18 restricts PEDV replication in Marc-145 cells via enhancing dephosphorylation of RIG-I. Vet Microbiol 2024; 294:110124. [PMID: 38795403 DOI: 10.1016/j.vetmic.2024.110124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/13/2024] [Accepted: 05/18/2024] [Indexed: 05/27/2024]
Abstract
PEDV, a single-stranded RNA virus, causes significant economic losses in the pig industry. Sin3-associated protein 18 (SAP18) is known for its role in transcriptional inhibition and RNA splicing. However, research on SAP18's involvement in PEDV infection is limited. Here, we identified an interaction between SAP18 and PEDV nonstructural protein 10 (Nsp10) using immunoprecipitation-mass spectrometry (IP-MS) and confirmed it through immunoprecipitation and laser confocal microscopy. Additionally, PEDV Nsp10 reduced SAP18 protein levels and induced its cytoplasmic accumulation. Overexpressing SAP18 suppressed PEDV replication, meanwhile its knockdown via short interfering RNA (siRNA) enhanced replication. SAP18 overexpression boosted IRF3 and NF-κB P65 phosphorylation, nuclear translocation, and IFN-β antiviral response. Furthermore, SAP18 upregulated RIG-I expression and facilitated its dephosphorylation, while SAP18 knockdown had the opposite effect. Finally, SAP18 interacted with phosphatase 1 (PP1) catalytic subunit alpha (PPP1CA), promoting PPP1CA-RIG-I interaction during PEDV infection. These findings highlight SAP18's role in activating the type I interferon pathway and inhibiting viral replication by promoting RIG-I dephosphorylation through its interaction with PPP1CA.
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Affiliation(s)
- Naling Yang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Qi Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Quanqiong Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Yanxia Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Shifan Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Yina Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Xiaojie Shi
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China
| | - Qinfan Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China.
| | - Xingang Xu
- College of Veterinary Medicine, Northwest A&F University, Yangling, Shanxi 712100, China.
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2
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Abbas H, Derkaoui DK, Jeammet L, Adicéam E, Tiollier J, Sicard H, Braun T, Poyet JL. Apoptosis Inhibitor 5: A Multifaceted Regulator of Cell Fate. Biomolecules 2024; 14:136. [PMID: 38275765 PMCID: PMC10813780 DOI: 10.3390/biom14010136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/17/2024] [Accepted: 01/19/2024] [Indexed: 01/27/2024] Open
Abstract
Apoptosis, or programmed cell death, is a fundamental process that maintains tissue homeostasis, eliminates damaged or infected cells, and plays a crucial role in various biological phenomena. The deregulation of apoptosis is involved in many human diseases, including cancer. One of the emerging players in the intricate regulatory network of apoptosis is apoptosis inhibitor 5 (API5), also called AAC-11 (anti-apoptosis clone 11) or FIF (fibroblast growth factor-2 interacting factor). While it may not have yet the same level of notoriety as some other cancer-associated proteins, API5 has garnered increasing attention in the cancer field in recent years, as elevated API5 levels are often associated with aggressive tumor behavior, resistance to therapy, and poor patient prognosis. This review aims to shed light on the multifaceted functions and regulatory mechanisms of API5 in cell fate decisions as well as its interest as therapeutic target in cancer.
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Affiliation(s)
- Hafsia Abbas
- Université Oran 1, Ahmed Ben Bella, Oran 31000, Algeria; (H.A.); (D.K.D.)
| | | | - Louise Jeammet
- Jalon Therapeutics, 75010 Paris, France; (L.J.); (J.T.); (H.S.)
| | - Emilie Adicéam
- Jalon Therapeutics, 75010 Paris, France; (L.J.); (J.T.); (H.S.)
| | - Jérôme Tiollier
- Jalon Therapeutics, 75010 Paris, France; (L.J.); (J.T.); (H.S.)
| | - Hélène Sicard
- Jalon Therapeutics, 75010 Paris, France; (L.J.); (J.T.); (H.S.)
| | - Thorsten Braun
- Laboratoire de Transfert des Leucémies, EA3518, Institut de Recherche Saint Louis, Hôpital Saint Louis, Université de Paris, 75010 Paris, France;
- AP-HP, Service d’Hématologie Clinique, Hôpital Avicenne, Université Paris XIII, 93000 Bobigny, France
- OPALE Carnot Institute, The Organization for Partnerships in Leukemia, Hôpital Saint-Louis, 75010 Paris, France
| | - Jean-Luc Poyet
- INSERM UMRS976, Institut de Recherche Saint Louis, Hôpital Saint Louis, 75010 Paris, France
- Université Paris Cité, 75015 Paris, France
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3
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Kumari S, Rehman A, Chandra P, Singh KK. Functional role of SAP18 protein: From transcriptional repression to splicing regulation. Cell Biochem Funct 2023; 41:738-751. [PMID: 37486712 DOI: 10.1002/cbf.3830] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/18/2023] [Accepted: 07/11/2023] [Indexed: 07/25/2023]
Abstract
Sin3 associated protein 18 (SAP18) is an evolutionary conserved protein, originally discovered in a complex with the transcriptional regulatory protein, Sin3. Subsequent investigations revealed SAP18 as an integral splicing component of the exon junction complex (EJC)-associated apoptosis-and splicing-associated protein (ASAP)/PNN-RNPS1-SAP18 (PSAP) complex. In association with Sin3, SAP18 contributes toward transcriptional repression of genes implicated in embryonic development, stress response, human immunodeficiency virus type 1 replication, and tumorigenesis. As a part of EJC, SAP18 mediates alternative splicing events and suppresses the cryptic splice sites present within flanking regions of exon-exon junctions. In this review, we provide a thorough discussion on SAP18, focussing on its conserved dual role in transcriptional regulation and messenger RNA splicing. Recent research on the involvement of SAP18 in the emergence of cancer and human disorders has also been highlighted. The potential of SAP18 as a therapeutic target is also discussed in these recent studies, particularly related to malignancies of the myeloid lineage.
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Affiliation(s)
- Sweta Kumari
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Ayushi Rehman
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Pratap Chandra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Kusum K Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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4
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Sybilska E, Daszkowska-Golec A. Alternative splicing in ABA signaling during seed germination. FRONTIERS IN PLANT SCIENCE 2023; 14:1144990. [PMID: 37008485 PMCID: PMC10060653 DOI: 10.3389/fpls.2023.1144990] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
Seed germination is an essential step in a plant's life cycle. It is controlled by complex physiological, biochemical, and molecular mechanisms and external factors. Alternative splicing (AS) is a co-transcriptional mechanism that regulates gene expression and produces multiple mRNA variants from a single gene to modulate transcriptome diversity. However, little is known about the effect of AS on the function of generated protein isoforms. The latest reports indicate that alternative splicing (AS), the relevant mechanism controlling gene expression, plays a significant role in abscisic acid (ABA) signaling. In this review, we present the current state of the art about the identified AS regulators and the ABA-related changes in AS during seed germination. We show how they are connected with the ABA signaling and the seed germination process. We also discuss changes in the structure of the generated AS isoforms and their impact on the functionality of the generated proteins. Also, we point out that the advances in sequencing technology allow for a better explanation of the role of AS in gene regulation by more accurate detection of AS events and identification of full-length splicing isoforms.
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5
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Sprague AC, Niu L, Jandarov R, Zhang X, Zhang G, Chen A, Šarac J, Čoklo M, Missoni S, Rudan P, Langevin SM, Deka R. Stable methylation loci are associated with systolic blood pressure in a Croatian island population. Epigenomics 2022; 14:1343-1354. [PMID: 36453021 PMCID: PMC9816922 DOI: 10.2217/epi-2022-0279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 11/03/2022] [Indexed: 12/03/2022] Open
Abstract
Background: The objective was to identify stable and dynamic DNA methylation loci associated with cardiometabolic traits among an adult population from the Croatian island of Hvar. Materials & methods: An epigenome-wide association study was conducted using peripheral blood longitudinally collected at two time points 10 years apart via Infinium MethylationEPIC beadarray (n = 112). Stable and dynamic loci were identified using linear mixed models. Associations between cardiometabolic traits and loci were assessed using linear models. Results: 22 CpG loci were significantly associated with systolic blood pressure. Twenty were stable and two were dynamic. Conclusion: Multiple genes may be involved in the determination of systolic blood pressure level via stable epigenetic programming, potentially established earlier in life.
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Affiliation(s)
- Alexander C Sprague
- Division of Epidemiology, Department of Environmental & Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Liang Niu
- Division of Biostatistics & Bioinformatics, Department of Environmental & Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Roman Jandarov
- Division of Biostatistics & Bioinformatics, Department of Environmental & Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Xiang Zhang
- Division of Environmental Genetics & Molecular Toxicology, Department of Environmental & Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Ge Zhang
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Aimin Chen
- Department of Biostatistics, Epidemiology & Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jelena Šarac
- Institute for Anthropological Research, Zagreb, Croatia
| | - Miran Čoklo
- Institute for Anthropological Research, Zagreb, Croatia
| | - Sasa Missoni
- Institute for Anthropological Research, Zagreb, Croatia
| | - Pavao Rudan
- Anthropological Center & Scientific Council for Anthropological Research, Croatian Academy of Arts & Sciences, Zagreb, Croatia
| | - Scott M Langevin
- Division of Epidemiology, Department of Environmental & Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
- University of Cincinnati Cancer Center, Cincinnati, OH 45267, USA
| | - Ranjan Deka
- Division of Epidemiology, Department of Environmental & Public Health Sciences, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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6
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Ashrafian S, Zarrineh M, Jensen P, Nawrocki A, Rezadoost H, Ansari AM, Farahmand L, Ghassempour A, Larsen MR. Quantitative Phosphoproteomics and Acetylomics of Safranal Anticancer Effects in Triple-Negative Breast Cancer Cells. J Proteome Res 2022; 21:2566-2585. [PMID: 36173113 DOI: 10.1021/acs.jproteome.2c00168] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Safranal, as an aroma in saffron, is one of the cytotoxic compounds in saffron that causes cell death in triple-negative breast cancer cells. Our recent research reported the anti-cancer effects of safranal, which further demonstrated its impact on protein translation, mitochondrial dysfunction, and DNA fragmentation. To better understand the underlying mechanisms, we identified acetylated and phosphorylated peptides in safranal-treated cancer cells. We conducted a comprehensive phosphoproteomics and acetylomics analysis of safranal-treated MDA-MB-231 cells by using a combination of TMT labeling and enrichment methods including titanium dioxide and immunoprecipitation. We provide a wide range of phosphoproteome regulation in different signaling pathways that are disrupted by safranal treatment. Safranal influences the phosphorylation level on proteins involved in DNA replication and repair, translation, and EGFR activation/accumulation, which can lead the cells into apoptosis. Safranal causes DNA damage which is followed by the activation of cell cycle checkpoints for DNA repair. Over time, checkpoints and DNA repair are inhibited and cells are under a mitotic catastrophe. Moreover, safranal prevents repair by the hypo-acetylation of H4 and facilitates the transcription of proapoptotic genes by hyper-acetylation of H3, which push the cells to the brink of death.
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Affiliation(s)
- Shahrbanou Ashrafian
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran 1983963113, Iran
| | - Mahshid Zarrineh
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran 1983963113, Iran.,Department of Oncology and Pathology, Science for Life Laboratory, Karolinska Institutet, Solna SE17165, Sweden
| | - Pia Jensen
- Protein Research Group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Arkadiusz Nawrocki
- Protein Research Group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Hassan Rezadoost
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran 1983963113, Iran
| | - Alireza Madjid Ansari
- Integrative Oncology Department, Breast Cancer Research Center, Moatamed Cancer Institute, ACECR, Tehran 1517964311, Iran
| | - Leila Farahmand
- Integrative Oncology Department, Breast Cancer Research Center, Moatamed Cancer Institute, ACECR, Tehran 1517964311, Iran
| | - Alireza Ghassempour
- Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran 1983963113, Iran
| | - Martin R Larsen
- Protein Research Group, Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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7
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Mikulski P, Wolff P, Lu T, Nielsen M, Echevarria EF, Zhu D, Questa JI, Saalbach G, Martins C, Dean C. VAL1 acts as an assembly platform co-ordinating co-transcriptional repression and chromatin regulation at Arabidopsis FLC. Nat Commun 2022; 13:5542. [PMID: 36130923 PMCID: PMC9492735 DOI: 10.1038/s41467-022-32897-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 08/23/2022] [Indexed: 12/04/2022] Open
Abstract
Polycomb (PcG) silencing is crucial for development, but how targets are specified remains incompletely understood. The cold-induced Polycomb Repressive Complex 2 (PRC2) silencing of Arabidopsis thaliana FLOWERING LOCUS C (FLC) provides an excellent system to elucidate PcG regulation. Association of the DNA binding protein VAL1 to FLC PcG nucleation regionis an important step. VAL1 co-immunoprecipitates APOPTOSIS AND SPLICING ASSOCIATED PROTEIN (ASAP) complex and PRC1. Here, we show that ASAP and PRC1 are necessary for co-transcriptional repression and chromatin regulation at FLC. ASAP mutants affect FLC transcription in warm conditions, but the rate of FLC silencing in the cold is unaffected. PRC1-mediated H2Aub accumulation increases at the FLC nucleation region during cold, but unlike the PRC2-delivered H3K27me3, does not spread across the locus. H2Aub thus involved in the transition to epigenetic silencing at FLC, facilitating H3K27me3 accumulation and long-term epigenetic memory. Overall, our work highlights the importance of VAL1 as an assembly platform co-ordinating activities necessary for epigenetic silencing at FLC.
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Affiliation(s)
- Pawel Mikulski
- Cell and Developmental Biology, John Innes Centre, Norwich, UK. .,Department of Biochemistry, University of Oxford, Oxford, UK.
| | - Philip Wolff
- Cell and Developmental Biology, John Innes Centre, Norwich, UK
| | - Tiancong Lu
- Cell and Developmental Biology, John Innes Centre, Norwich, UK.,State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Mathias Nielsen
- Cell and Developmental Biology, John Innes Centre, Norwich, UK
| | | | - Danling Zhu
- Cell and Developmental Biology, John Innes Centre, Norwich, UK.,SUSTech-PKU Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Julia I Questa
- Cell and Developmental Biology, John Innes Centre, Norwich, UK.,Centre for Research in Agricultural Genomics, Barcelona, Spain
| | | | - Carlo Martins
- Biological Chemistry, John Innes Centre, Norwich, UK
| | - Caroline Dean
- Cell and Developmental Biology, John Innes Centre, Norwich, UK. .,MRC Laboratory of Molecular Biology, Cambridge, UK.
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8
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Activation of CD44/PAK1/AKT signaling promotes resistance to FGFR1 inhibition in squamous-cell lung cancer. NPJ Precis Oncol 2022; 6:52. [PMID: 35853934 PMCID: PMC9296622 DOI: 10.1038/s41698-022-00296-2] [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: 09/24/2021] [Accepted: 06/08/2022] [Indexed: 12/24/2022] Open
Abstract
Lung cancer is the leading cause of cancer-related deaths worldwide. Fibroblast growth factor receptor 1 (FGFR1) gene amplification is one of the most prominent and potentially targetable genetic alterations in squamous-cell lung cancer (SQCLC). Highly selective tyrosine kinase inhibitors have been developed to target FGFR1; however, resistance mechanisms originally existing in patients or acquired during treatment have so far led to limited treatment efficiency in clinical trials. In this study we performed a wide-scale phosphoproteomic mass-spectrometry analysis to explore signaling pathways that lead to resistance toward FGFR1 inhibition in lung cancer cells that display (i) intrinsic, (ii) pharmacologically induced and (iii) mutationally induced resistance. Additionally, we correlated AKT activation to CD44 expression in 175 lung cancer patient samples. We identified a CD44/PAK1/AKT signaling axis as a commonly occurring resistance mechanism to FGFR1 inhibition in lung cancer. Co-inhibition of AKT/FGFR1, CD44/FGFR1 or PAK1/FGFR1 sensitized ‘intrinsically resistant’ and ‘induced-resistant’ lung-cancer cells synergetically to FGFR1 inhibition. Furthermore, strong CD44 expression was significantly correlated with AKT activation in SQCLC patients. Collectively, our phosphoproteomic analysis of lung-cancer cells resistant to FGFR1 inhibitor provides a large data library of resistance-associated phosphorylation patterns and leads to the proposal of a common resistance pathway comprising CD44, PAK1 and AKT activation. Examination of CD44/PAK1/AKT activation could help to predict response to FGFR1 inhibition. Moreover, combination between AKT and FGFR1 inhibitors may pave the way for an effective therapy of patients with treatment-resistant FGFR1-dependent lung cancer.
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9
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Schlautmann LP, Lackmann JW, Altmüller J, Dieterich C, Boehm V, Gehring NH. Exon junction complex-associated multi-adapter RNPS1 nucleates splicing regulatory complexes to maintain transcriptome surveillance. Nucleic Acids Res 2022; 50:5899-5918. [PMID: 35640609 PMCID: PMC9178013 DOI: 10.1093/nar/gkac428] [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: 08/20/2021] [Revised: 05/05/2022] [Accepted: 05/10/2022] [Indexed: 12/04/2022] Open
Abstract
The exon junction complex (EJC) is an RNA-binding multi-protein complex with critical functions in post-transcriptional gene regulation. It is deposited on the mRNA during splicing and regulates diverse processes including pre-mRNA splicing and nonsense-mediated mRNA decay (NMD) via various interacting proteins. The peripheral EJC-binding protein RNPS1 was reported to serve two insufficiently characterized functions: suppressing mis-splicing of cryptic splice sites and activating NMD in the cytoplasm. The analysis of transcriptome-wide effects of EJC and RNPS1 knockdowns in different human cell lines supports the conclusion that RNPS1 can moderately influence NMD activity, but is not a globally essential NMD factor. However, numerous aberrant splicing events strongly suggest that the main function of RNPS1 is splicing regulation. Rescue analyses revealed that the RRM and C-terminal domain of RNPS1 both contribute partially to regulate RNPS1-dependent splicing events. We defined the RNPS1 core interactome using complementary immunoprecipitations and proximity labeling, which identified interactions with splicing-regulatory factors that are dependent on the C-terminus or the RRM domain of RNPS1. Thus, RNPS1 emerges as a multifunctional splicing regulator that promotes correct and efficient splicing of different vulnerable splicing events via the formation of diverse splicing-promoting complexes.
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Affiliation(s)
- Lena P Schlautmann
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50937 Cologne, Germany
| | - Jan-Wilm Lackmann
- CECAD Research Center, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Janine Altmüller
- Cologne Center for Genomics (CCG), University of Cologne, 50931 Cologne, Germany
| | - Christoph Dieterich
- Section of Bioinformatics and Systems Cardiology, Department of Internal Medicine III and Klaus Tschira Institute for Integrative Computational Cardiology, Heidelberg University Hospital, 69120 Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Volker Boehm
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50937 Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, 50937 Cologne, Germany
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10
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No-nonsense: insights into the functional interplay of nonsense-mediated mRNA decay factors. Biochem J 2022; 479:973-993. [PMID: 35551602 PMCID: PMC9162471 DOI: 10.1042/bcj20210556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 04/10/2022] [Accepted: 04/12/2022] [Indexed: 11/22/2022]
Abstract
Nonsense-mediated messenger RNA decay (NMD) represents one of the main surveillance pathways used by eukaryotic cells to control the quality and abundance of mRNAs and to degrade viral RNA. NMD recognises mRNAs with a premature termination codon (PTC) and targets them to decay. Markers for a mRNA with a PTC, and thus NMD, are a long a 3′-untranslated region and the presence of an exon-junction complex (EJC) downstream of the stop codon. Here, we review our structural understanding of mammalian NMD factors and their functional interplay leading to a branched network of different interconnected but specialised mRNA decay pathways. We discuss recent insights into the potential impact of EJC composition on NMD pathway choice. We highlight the coexistence and function of different isoforms of up-frameshift protein 1 (UPF1) with an emphasis of their role at the endoplasmic reticulum and during stress, and the role of the paralogs UPF3B and UPF3A, underscoring that gene regulation by mammalian NMD is tightly controlled and context-dependent being conditional on developmental stage, tissue and cell types.
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11
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RNPS1 inhibits excessive tumor necrosis factor/tumor necrosis factor receptor signaling to support hematopoiesis in mice. Proc Natl Acad Sci U S A 2022; 119:e2200128119. [PMID: 35482923 DOI: 10.1073/pnas.2200128119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SignificanceMessenger RNA (mRNA) splicing is fundamental to protein expression in mammals. Homozygous deletion of single protein components of the splicing machinery or its regulatory factors is embryonic lethal. However, through forward genetic screening in mice, we identified a viable hypomorphic missense mutation of the splicing regulator RNPS1. Homozygous mutant mice displayed altered immune cell development due to excessive tumor necrosis factor (TNF)-dependent immune cell apoptosis. Splicing was impaired in CD8+ T cells and hematopoietic stem cells from RNPS1 mutant mice. TNF knockout rescued hematopoiesis and dramatically reduced splicing defects in RNPS1 hematopoietic cells, demonstrating a surprising link between elevated TNF and defects in splicing caused by RNPS1 deficiency.
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12
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Nandi N, Zaidi Z, Tracy C, Krämer H. A phospho-switch at Acinus-Serine 437 controls autophagic responses to Cadmium exposure and neurodegenerative stress. eLife 2022; 11:72169. [PMID: 35037620 PMCID: PMC8794470 DOI: 10.7554/elife.72169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 01/14/2022] [Indexed: 12/09/2022] Open
Abstract
Neuronal health depends on quality control functions of autophagy, but mechanisms regulating neuronal autophagy are poorly understood. Previously, we showed that in Drosophila starvation-independent quality control autophagy is regulated by acinus (acn) and the Cdk5-dependent phosphorylation of its serine437 (Nandi et al., 2017). Here, we identify the phosphatase that counterbalances this activity and provides for the dynamic nature of acinus-serine437 (acn-S437) phosphorylation. A genetic screen identified six phosphatases that genetically interacted with an acn gain-of-function model. Among these, loss of function of only one, the PPM-type phosphatase Nil (CG6036), enhanced pS437-acn levels. Cdk5-dependent phosphorylation of acn-S437 in nil1 animals elevates neuronal autophagy and reduces the accumulation of polyQ proteins in a Drosophila Huntington’s disease model. Consistent with previous findings that Cd2+ inhibits PPM-type phosphatases, Cd2+ exposure elevated acn-S437 phosphorylation which was necessary for increased neuronal autophagy and protection against Cd2+-induced cytotoxicity. Together, our data establish the acn-S437 phosphoswitch as critical integrator of multiple stress signals regulating neuronal autophagy.
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Affiliation(s)
- Nilay Nandi
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Zuhair Zaidi
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Charles Tracy
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
| | - Helmut Krämer
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, United States
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13
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The role and regulation of Pnn in proliferative and non-dividing cells: Form embryogenesis to pathogenesis. Biochem Pharmacol 2021; 192:114672. [PMID: 34237338 DOI: 10.1016/j.bcp.2021.114672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/30/2021] [Accepted: 07/02/2021] [Indexed: 11/20/2022]
Abstract
Pnn, a multiple functional protein, plays roles in embryonic development, cellular differentiation, tumorigenesis, and metastasis. In the past two decades, the functions of Pnn in regulating RNA alternative splicing, gene regulation, and cell-cell connection have been revealed. Although Pnn is originally identified as a desmosome-associated protein for linking desmosome and intermediated filament, emerging evidence implies that Pnn not only is a desmosome protein but also plays critical roles in the nucleus. To date, through cell biology investigation and the generation of animal models with genetic manipulation, the physiological role of Pnn has been characterized in the research fields of developmental biology, tumor biology, and neuroscience. Through proteomic and molecular biology studies, transcription regulators, splicing regulators, and cytoskeletal proteins were found to interact with Pnn. In addition, histopathological and biochemical evidence has pointed to an association of Pnn expression level with tumorigenesis and metastasis. A previous clinical study also demonstrated a correlation between a reduced expression of Pnn and human dementia. Besides, experimental studies showed a protective role of Pnn against ischemic stress in astrocytes. All indicated a variety of roles of Pnn in different cell types. In this review article, we introduced the role of Pnn in embryogenesis and pathogenesis as well as discussed its potential clinical application.
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Arabidopsis ACINUS is O-glycosylated and regulates transcription and alternative splicing of regulators of reproductive transitions. Nat Commun 2021; 12:945. [PMID: 33574257 PMCID: PMC7878923 DOI: 10.1038/s41467-021-20929-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 12/17/2020] [Indexed: 01/30/2023] Open
Abstract
O-GlcNAc modification plays important roles in metabolic regulation of cellular status. Two homologs of O-GlcNAc transferase, SECRET AGENT (SEC) and SPINDLY (SPY), which have O-GlcNAc and O-fucosyl transferase activities, respectively, are essential in Arabidopsis but have largely unknown cellular targets. Here we show that AtACINUS is O-GlcNAcylated and O-fucosylated and mediates regulation of transcription, alternative splicing (AS), and developmental transitions. Knocking-out both AtACINUS and its distant paralog AtPININ causes severe growth defects including dwarfism, delayed seed germination and flowering, and abscisic acid (ABA) hypersensitivity. Transcriptomic and protein-DNA/RNA interaction analyses demonstrate that AtACINUS represses transcription of the flowering repressor FLC and mediates AS of ABH1 and HAB1, two negative regulators of ABA signaling. Proteomic analyses show AtACINUS's O-GlcNAcylation, O-fucosylation, and association with splicing factors, chromatin remodelers, and transcriptional regulators. Some AtACINUS/AtPININ-dependent AS events are altered in the sec and spy mutants, demonstrating a function of O-glycosylation in regulating alternative RNA splicing.
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15
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Floyd BM, Drew K, Marcotte EM. Systematic Identification of Protein Phosphorylation-Mediated Interactions. J Proteome Res 2021; 20:1359-1370. [PMID: 33476154 DOI: 10.1021/acs.jproteome.0c00750] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein phosphorylation is a key regulatory mechanism involved in nearly every eukaryotic cellular process. Increasingly sensitive mass spectrometry approaches have identified hundreds of thousands of phosphorylation sites, but the functions of a vast majority of these sites remain unknown, with fewer than 5% of sites currently assigned a function. To increase our understanding of functional protein phosphorylation we developed an approach (phospho-DIFFRAC) for identifying the phosphorylation-dependence of protein assemblies in a systematic manner. A combination of nonspecific protein phosphatase treatment, size-exclusion chromatography, and mass spectrometry allowed us to identify changes in protein interactions after the removal of phosphate modifications. With this approach we were able to identify 316 proteins involved in phosphorylation-sensitive interactions. We recovered known phosphorylation-dependent interactors such as the FACT complex and spliceosome, as well as identified novel interactions such as the tripeptidyl peptidase TPP2 and the supraspliceosome component ZRANB2. More generally, we find phosphorylation-dependent interactors to be strongly enriched for RNA-binding proteins, providing new insight into the role of phosphorylation in RNA binding. By searching directly for phosphorylated amino acid residues in mass spectrometry data, we identified the likely regulatory phosphosites on ZRANB2 and FACT complex subunit SSRP1. This study provides both a method and resource for obtaining a better understanding of the role of phosphorylation in native macromolecular assemblies. All mass spectrometry data are available through PRIDE (accession #PXD021422).
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Affiliation(s)
- Brendan M Floyd
- Department of Molecular Biosciences Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Kevin Drew
- Department of Molecular Biosciences Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Edward M Marcotte
- Department of Molecular Biosciences Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, Texas 78712, United States
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Bhatia D, Hinsu A, Panchal K, Sabara P, Jakhesara S, Koringa P. Molecular portrait of squamous cell carcinoma of the bovine horn evaluated by high-throughput targeted exome sequencing: a preliminary report. BMC Vet Res 2020; 16:461. [PMID: 33243240 PMCID: PMC7690171 DOI: 10.1186/s12917-020-02683-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 11/18/2020] [Indexed: 02/04/2023] Open
Abstract
Background Squamous Cell Carcinoma of horn, also known as horn cancer, is a prevailing type of cancer in cattles especially Bos indicus. It is one of the most prevalent disease in Indian bullocks often resulting in death and huge economic losses to farmers. Here, we have reported the use of targeted exome sequencing to identify variants present in horn cancer affected horn mucosa tissue and blood of the same animal to identify some of the prevalent markers of horn cancer. Results We have observed higher number of variants present in tissue as compared to blood as well as among cancer samples compared to samples from normal animals. Eighty six and 1437 cancer-specific variants were identified among the predicted variants in blood and tissue samples, respectively. Total 25 missense variants were observed distributed over 18 genes. KRT8 gene coding for Keratin8, one of the key constituents of horn, displayed 5 missense variants. Additionally, three other genes involved in apoptosis pathway and two genes involved in antigen presentation and processing also contained variants. Conclusions Several genes involved in various apoptotic pathways were found to contain non-synonymous mutations. Keratin8 coding for Keratin, a chief constituent of horn was observed to have the highest number of mutations. In all, we present a preliminary report of mutations observed in horn cancer. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-020-02683-y.
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Affiliation(s)
- Dhruv Bhatia
- Department of Animal Biotechnology, College of Veterinary Sciences & A.H., Anand Agricultural University, Anand, 388001, India
| | - Ankit Hinsu
- Department of Animal Biotechnology, College of Veterinary Sciences & A.H., Anand Agricultural University, Anand, 388001, India
| | - Ketankumar Panchal
- Department of Animal Biotechnology, College of Veterinary Sciences & A.H., Anand Agricultural University, Anand, 388001, India
| | - Pritesh Sabara
- Department of Animal Biotechnology, College of Veterinary Sciences & A.H., Anand Agricultural University, Anand, 388001, India
| | - Subhash Jakhesara
- Department of Animal Biotechnology, College of Veterinary Sciences & A.H., Anand Agricultural University, Anand, 388001, India
| | - Prakash Koringa
- Department of Animal Biotechnology, College of Veterinary Sciences & A.H., Anand Agricultural University, Anand, 388001, India.
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Expression and Distribution Pattern of Pnn in Ischemic Cerebral Cortex and Cultured Neural Cells Exposed to Oxygen-Glucose Deprivation. Brain Sci 2020; 10:brainsci10100708. [PMID: 33027948 PMCID: PMC7599571 DOI: 10.3390/brainsci10100708] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 10/03/2020] [Indexed: 12/23/2022] Open
Abstract
Pinin (Pnn), a multifunctional protein, participates in embryonic development as well as in cellular apoptosis, proliferation, and migration through regulating mRNA alternative splicing and gene transcription. Previous studies have shown that Pnn plays important roles in neural system development and the expression level of Pnn in astrocytes is altered by ischemic stress and associated with cellular apoptosis. In the present study, we further utilized primary cultured rat neurons and astrocytes with oxygen-glucose deprivation (OGD) and a mouse model with middle cerebral artery occlusion (MCAO)-induced ischemic stroke to examine the effect of ischemic stress on Pnn expression and distribution in different types of neural cells. Under normoxia, Pnn is mainly localized in the nuclear speckle of primary cultured neurons. The expression level of Pnn was increased after the OGD treatment and then decreased in the reoxygenation period. Moreover, the cytoplasmic expression of Pnn was observed in neurons with OGD and reoxygenation (OGD/R). Unlike that in neurons, the Pnn expression in astrocytes was decreased after OGD treatment and then gradually increased during the reoxygenation period. Of interest, the nuclear–cytoplasmic translocation of Pnn was not observed in astrocytes with OGD/R. In the MCAO mouse model, the neuronal expression of Pnn in the peri-ischemic region was reduced by three days post induction of ischemic stroke. However, the Pnn expression in astrocytes was not altered. Moreover, the nuclear speckle distribution of Pnn in neurons was also diminished following ischemic stroke. In conclusion, the Pnn expression and distribution after OGD and during reoxygenation showed distinct manners in neurons and astrocytes, implying that Pnn may play different roles in different types of neural cells in the stress response to ischemic injury.
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Efficient Therapeutic Delivery by a Novel Cell-Penetrating Peptide Derived from Acinus. Cancers (Basel) 2020; 12:cancers12071858. [PMID: 32664285 PMCID: PMC7408964 DOI: 10.3390/cancers12071858] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/03/2020] [Accepted: 07/06/2020] [Indexed: 02/07/2023] Open
Abstract
In this study, we have identified a novel cell-penetrating sequence, termed hAP10, from the C-terminus of the human protein Acinus. hAP10 was able to efficiently enter various normal and cancerous cells, likely through an endocytosis pathway, and to deliver an EGFP cargo to the cell interior. Cell penetration of a peptide, hAP10DR, derived from hAP10 by mutation of an aspartic acid residue to an arginine was dramatically increased. Interestingly, a peptide containing a portion of the heptad leucine repeat region domain of the survival protein AAC-11 (residues 377–399) fused to either hAP10 or hAP10DR was able to induce tumor cells, but not normal cells, death both ex vivo on Sézary patients’ circulating cells and to inhibit tumor growth in vivo in a sub-cutaneous xenograft mouse model for the Sézary syndrome. Combined, our results indicate that hAP10 and hAP10DR may represent promising vehicles for the in vitro or in vivo delivery of bioactive cargos, with potential use in clinical settings.
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Lin YC, Lu YH, Lee YC, Hung CS, Lin JC. Altered expressions and splicing profiles of Acin1 transcripts differentially modulate brown adipogenesis through an alternative splicing mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194601. [PMID: 32629174 DOI: 10.1016/j.bbagrm.2020.194601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/26/2020] [Accepted: 06/28/2020] [Indexed: 10/23/2022]
Abstract
Apoptotic chromatin condensation inducer in the nucleus (also referred as Acin1) was first characterized as an RNA-binding protein involved in apoptosis. In later reports, Acin1 was identified as an auxiliary component of the exon junction complex (EJC) which is assembled throughout pre-messenger RNA splicing. In this study, results of whole-transcriptome analyses revealed reduced expressions and reprogrammed splicing profiles of Acin1 transcripts throughout development of brown adipose tissues (BATs) that execute non-shivering thermogenesis in small rodents and infants by consuming lipids. Depletion of endogenous Acin1 isoforms led to activation of brown adipogenic signatures in mouse C3H10T1/2 fibroblasts. Nevertheless, overexpressions of the Acin1-L or Acin1-S isoform exerted discriminative influences on brown adipogenesis and reprogramming of the expression of serine/arginine-rich splicing factor 3 (SRSF3) through an alternative splicing-coupled nonsense-mediated decay mechanism in a sequence-specific manner. Moreover, the Acin1-SRSF3 axis constitutes a regulatory pathway that participates in the brown adipocyte-related splicing network. Taken together, the interplay between accessory EJC components and splicing regulators constitutes an emerging mechanism for differentially manipulating the activity of brown adipogenesis via alternative splicing network.
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Affiliation(s)
- Ying-Chin Lin
- Department of Family Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Yi-Han Lu
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yuan-Chii Lee
- Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan
| | - Ching-Sheng Hung
- PhD Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; PhD Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
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20
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Whole-Organ Genomic Characterization of Mucosal Field Effects Initiating Bladder Carcinogenesis. Cell Rep 2020; 26:2241-2256.e4. [PMID: 30784602 DOI: 10.1016/j.celrep.2019.01.095] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 12/12/2018] [Accepted: 01/25/2019] [Indexed: 12/13/2022] Open
Abstract
We used whole-organ mapping to study the locoregional molecular changes in a human bladder containing multifocal cancer. Widespread DNA methylation changes were identified in the entire mucosa, representing the initial field effect. The field effect was associated with subclonal low-allele frequency mutations and a small number of DNA copy alterations. A founder mutation in the RNA splicing gene, ACIN1, was identified in normal mucosa and expanded clonally with an additional 21 mutations in progression to carcinoma. The patterns of mutations and copy number changes in carcinoma in situ and foci of carcinoma were almost identical, confirming their clonal origins. The pathways affected by the DNA copy alterations and mutations, including the Kras pathway, were preceded by the field changes in DNA methylation, suggesting that they reinforced mechanisms that had already been initiated by methylation. The results demonstrate that DNA methylation can serve as the initiator of bladder carcinogenesis.
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21
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Tyra LK, Nandi N, Tracy C, Krämer H. Yorkie Growth-Promoting Activity Is Limited by Atg1-Mediated Phosphorylation. Dev Cell 2020; 52:605-616.e7. [PMID: 32032548 DOI: 10.1016/j.devcel.2020.01.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/26/2019] [Accepted: 01/09/2020] [Indexed: 01/31/2023]
Abstract
The expression of multiple growth-promoting genes is coordinated by the transcriptional co-activator Yorkie with its major regulatory input provided by the Hippo-Warts kinase cascade. Here, we identify Atg1/ULK1-mediated phosphorylation of Yorkie as an additional inhibitory input independent of the Hippo-Warts pathway. Two serine residues in Yorkie, S74 and S97, are Atg1/ULK1 consensus target sites and are phosphorylated by ULK1 in vitro, thereby preventing its binding to Scalloped. In vivo, gain of function of Atg1, or its activator Acinus, caused elevated Yorkie phosphorylation and inhibited Yorkie's growth-promoting activity. Loss of function of Atg1 or Acinus raised expression of Yorkie target genes and increased tissue size. Unlike Atg1's role in autophagy, Atg1-mediated phosphorylation of Yorkie does not require Atg13. Atg1 is activated by starvation and other cellular stressors and therefore can impose temporary stress-induced constraints on the growth-promoting gene networks under the control of Hippo-Yorkie signaling.
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Affiliation(s)
- Lauren K Tyra
- Peter O'Donnell Jr. Brain Institute, Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390-9111, USA
| | - Nilay Nandi
- Peter O'Donnell Jr. Brain Institute, Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390-9111, USA
| | - Charles Tracy
- Peter O'Donnell Jr. Brain Institute, Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390-9111, USA
| | - Helmut Krämer
- Peter O'Donnell Jr. Brain Institute, Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75390-9111, USA; Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390-9111, USA.
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22
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Zhang Z, Guo M, Liu Y, Liu P, Cao X, Xu Y, Zhu X. RNPS1 inhibition aggravates ischemic brain injury and promotes neuronal death. Biochem Biophys Res Commun 2019; 523:39-45. [PMID: 31831174 DOI: 10.1016/j.bbrc.2019.11.185] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 11/28/2019] [Indexed: 12/13/2022]
Abstract
RNA-binding protein with serine-rich domain 1 (RNPS1) is essential for modulating mRNA metabolism, but its role in ischemic stroke is unknown. In this study, we found that RNPS1 expression was significantly up-regulated in the brains of ischemic stroke mice and primary cortical neurons after oxygen-glucose deprivation (OGD) treatment. Knockdown of RNPS1 significantly aggravated ischemic brain injury after middle cerebral artery occlusion (MCAO) and promoted neuronal death. In addition, knockdown of RNPS1 exacerbated ischemia induced neuronal apoptosis, and downregulated the expression of anti-apoptotic proteins Bcl-xL and Mcl-1. Our study suggested that RNPS1 might be a potential therapeutic target for alleviating neuronal death in ischemic stroke.
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Affiliation(s)
- Zhi Zhang
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Department of Neurology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Mengdi Guo
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Ying Liu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Pinyi Liu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Department of Neurology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Xiang Cao
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Yun Xu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Department of Neurology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China
| | - Xiaolei Zhu
- Department of Neurology, Drum Tower Hospital, Medical School and The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, 210008, China; Jiangsu Key Laboratory for Molecular Medicine, Medical School of Nanjing University, Nanjing, 210093, China.
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23
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Storing memories: the distinct phases of Polycomb-mediated silencing of Arabidopsis FLC. Biochem Soc Trans 2019; 47:1187-1196. [DOI: 10.1042/bst20190255] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 06/06/2019] [Accepted: 06/14/2019] [Indexed: 12/19/2022]
Abstract
Abstract
Polycomb-mediated epigenetic silencing is central to correct growth and development in higher eukaryotes. The evolutionarily conserved Polycomb repressive complex 2 (PRC2) transcriptionally silences target genes through a mechanism requiring the histone modification H3K27me3. However, we still do not fully understand what defines Polycomb targets, how their expression state is switched from epigenetically ON to OFF and how silencing is subsequently maintained through many cell divisions. An excellent system in which to dissect the sequence of events underlying an epigenetic switch is the Arabidopsis FLC locus. Exposure to cold temperatures progressively induces a PRC2-dependent switch in an increasing proportion of cells, through a mechanism that is driven by the local chromatin environment. Temporally distinct phases of this silencing mechanism have been identified. First, the locus is transcriptionally silenced in a process involving cold-induced antisense transcripts; second, nucleation at the first exon/intron boundary of a Polycomb complex containing cold-induced accessory proteins induces a metastable epigenetically silenced state; third, a Polycomb complex with a distinct composition spreads across the locus in a process requiring DNA replication to deliver long-term epigenetic silencing. Detailed understanding from this system is likely to provide mechanistic insights important for epigenetic silencing in eukaryotes generally.
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Deka B, Singh K. The arginine and serine-rich domains of Acinus modulate splicing. Cell Biol Int 2019; 43:954-959. [PMID: 31070279 DOI: 10.1002/cbin.11163] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 05/05/2019] [Indexed: 01/05/2023]
Abstract
Apoptotic chromatin condensation inducer in the nucleus (Acinus) is an RNA-binding protein that has a functional role in inducing apoptotic chromatin condensation and regulating messenger RNA (mRNA) processing. Acinus interacts with the spliceosomal machinery and is a member of the ASAP (apoptosis and splicing-associated protein complex) as well as the EJC (exon junction complex), which gets deposited onto mRNA during splicing. In this study, we have used in vivo splicing assays to characterize the function of Acinus in pre-mRNA splicing more closely. We show that full-length Acinus-S', an isoform of Acinus, does not have a role in modulating splice site selection in human immunodeficiency virus 1 minigene reporter system. In contrast, we observed that the tethering of arginine/serine (RS) and RNPS1-SAP18-binding (RSB) domains of Acinus could regulate the selection of alternative splice sites, thereby revealing the potential of Acinus in stimulating alternative splicing. Altogether, our data suggest that the RS and RSB domains play a critical role in regulating splicing activity via selection of distinct splice sites during pre-mRNA splicing.
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Affiliation(s)
- Bhagyashree Deka
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - KusumK Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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Suppression of the SAP18/HDAC1 complex by targeting TRIM56 and Nanog is essential for oncogenic viral FLICE-inhibitory protein-induced acetylation of p65/RelA, NF-κB activation, and promotion of cell invasion and angiogenesis. Cell Death Differ 2019; 26:1970-1986. [PMID: 30670829 DOI: 10.1038/s41418-018-0268-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 12/26/2022] Open
Abstract
Kaposi's sarcoma (KS), a highly invasive and angiogenic tumor of endothelial spindle-shaped cells, is the most common AIDS-associated cancer caused by KS-associated herpesvirus (KSHV) infection. KSHV-encoded viral FLICE-inhibitory protein (vFLIP) is a viral oncogenic protein, but its role in the dissemination and angiogenesis of KSHV-induced cancers remains unknown. Here, we report that vFLIP facilitates cell migration, invasion, and angiogenesis by downregulating the SAP18-HDAC1 complex. vFLIP degrades SAP18 through a ubiquitin-proteasome pathway by recruiting E3 ubiquitin ligase TRIM56. Further, vFLIP represses HDAC1, a protein partner of SAP18, by inhibiting Nanog occupancy on the HDAC1 promoter. Notably, vFLIP impairs the interaction between the SAP18/HDAC1 complex and p65 subunit, leading to enhancement of p65 acetylation and NF-κB activation. Our data suggest a novel mechanism of vFLIP activation of the NF-κB by decreasing the SAP18/HDAC1 complex to promote the acetylation of p65 subunit, which contributes to vFLIP-induced activation of the NF-κB pathway, cell invasion, and angiogenesis. These findings advance our understanding of the mechanism of KSHV-induced pathogenesis, and providing a rationale for therapeutic targeting of the vFLIP/SAP18/HDAC1 complex as a novel strategy of AIDS-KS.
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Chen SL, Rooney TJ, Hu AR, Beard HS, Garrett WM, Mangalath LM, Powers JJ, Cooper B, Zhang XN. Quantitative Proteomics Reveals a Role for SERINE/ARGININE-Rich 45 in Regulating RNA Metabolism and Modulating Transcriptional Suppression via the ASAP Complex in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2019; 10:1116. [PMID: 31608083 PMCID: PMC6761909 DOI: 10.3389/fpls.2019.01116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/14/2019] [Indexed: 05/12/2023]
Abstract
Pre-mRNA alternative splicing is a conserved mechanism for eukaryotic cells to leverage existing genetic resources to create a diverse pool of protein products. It is regulated in coordination with other events in RNA metabolism such as transcription, polyadenylation, RNA transport, and nonsense-mediated decay via protein networks. SERINE/ARGININE-RICH 45 (SR45) is thought to be a neutral splicing regulator. It is orthologous to a component of the apoptosis and splicing-associated protein (ASAP) complex functioning to regulate RNA metabolism at multiple levels. Within this context, we try to understand why the sr45-1 mutant Arabidopsis has malformed flowers, delayed flowering time, and increased disease resistance. Prior studies revealed increased expression for some disease resistance genes and the flowering suppressor Flowering Locus C (FLC) in sr45-1 mutants and a physical association between SR45 and reproductive process-related RNAs. Here, we used Tandem Mass Tag-based quantitative mass spectrometry to compare the protein abundance from inflorescence between Arabidopsis wild-type (Col-0) and sr45-1 mutant plants. A total of 7,206 proteins were quantified, of which 227 proteins exhibited significantly different accumulation. Only a small percentage of these proteins overlapped with the dataset of RNAs with altered expression. The proteomics results revealed that the sr45-1 mutant had increased amounts of enzymes for glucosinolate biosynthesis which are important for disease resistance. Furthermore, the mutant inflorescence had a drastically reduced amount of the Sin3-associated protein 18 (SAP18), a second ASAP complex component, despite no significant reduction in SAP18 RNA. The third ASAP component protein, ACINUS, also had lower abundance without significant RNA changes in the sr45-1 mutant. To test the effect of SR45 on SAP18, a SAP18-GFP fusion protein was overproduced in transgenic Arabidopsis Col-0 and sr45-1 plants. SAP18-GFP has less accumulation in the nucleus, the site of activity for the ASAP complex, without SR45. Furthermore, transgenic sr45-1 mutants overproducing SAP18-GFP expressed even more FLC and had a more severe flowering delay than non-transgenic sr45-1 mutants. These results suggest that SR45 is required to maintain the wild-type level of SAP18 protein accumulation in the nucleus and that FLC-regulated flowering time is regulated by the correct expression and localization of the ASAP complex.
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Affiliation(s)
- Samuel L. Chen
- Bioinformatics Program, St. Bonaventure University, St. Bonaventure, NY, United States
| | - Timothy J. Rooney
- Biochemistry Program, St. Bonaventure University, St. Bonaventure, NY, United States
| | - Anna R. Hu
- Biochemistry Program, St. Bonaventure University, St. Bonaventure, NY, United States
| | - Hunter S. Beard
- Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD, United States
| | - Wesley M. Garrett
- Animal Biosciences & Biotechnology Laboratory, USDA-ARS, Beltsville, MD, United States
| | - Leann M. Mangalath
- Department of Biology, St. Bonaventure University, St. Bonaventure, NY, United States
| | - Jordan J. Powers
- Biochemistry Program, St. Bonaventure University, St. Bonaventure, NY, United States
| | - Bret Cooper
- Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD, United States
| | - Xiao-Ning Zhang
- Biochemistry Program, St. Bonaventure University, St. Bonaventure, NY, United States
- Department of Biology, St. Bonaventure University, St. Bonaventure, NY, United States
- *Correspondence: Xiao-Ning Zhang,
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27
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Genome-wide CRISPR-Cas9 Interrogation of Splicing Networks Reveals a Mechanism for Recognition of Autism-Misregulated Neuronal Microexons. Mol Cell 2018; 72:510-524.e12. [DOI: 10.1016/j.molcel.2018.10.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/27/2018] [Accepted: 10/04/2018] [Indexed: 12/22/2022]
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28
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Fernandes H, Czapinska H, Grudziaz K, Bujnicki JM, Nowacka M. Crystal structure of human Acinus RNA recognition motif domain. PeerJ 2018; 6:e5163. [PMID: 30042883 PMCID: PMC6057467 DOI: 10.7717/peerj.5163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/14/2018] [Indexed: 12/13/2022] Open
Abstract
Acinus is an abundant nuclear protein involved in apoptosis and splicing. It has been implicated in inducing apoptotic chromatin condensation and DNA fragmentation during programmed cell death. Acinus undergoes activation by proteolytic cleavage that produces a truncated p17 form that comprises only the RNA recognition motif (RRM) domain. We have determined the crystal structure of the human Acinus RRM domain (AcRRM) at 1.65 Å resolution. It shows a classical four-stranded antiparallel β-sheet fold with two flanking α-helices and an additional, non-classical α-helix at the C-terminus, which harbors the caspase-3 target sequence that is cleaved during Acinus activation. In the structure, the C-terminal α-helix partially occludes the potential ligand binding surface of the β-sheet and hypothetically shields it from non-sequence specific interactions with RNA. Based on the comparison with other RRM-RNA complex structures, it is likely that the C-terminal α-helix changes its conformation with respect to the RRM core in order to enable RNA binding by Acinus.
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Affiliation(s)
- Humberto Fernandes
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Honorata Czapinska
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Katarzyna Grudziaz
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.,Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
| | - Martyna Nowacka
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
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29
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Banks CAS, Thornton JL, Eubanks CG, Adams MK, Miah S, Boanca G, Liu X, Katt ML, Parmely TJ, Florens L, Washburn MP. A Structured Workflow for Mapping Human Sin3 Histone Deacetylase Complex Interactions Using Halo-MudPIT Affinity-Purification Mass Spectrometry. Mol Cell Proteomics 2018; 17:1432-1447. [PMID: 29599190 PMCID: PMC6030732 DOI: 10.1074/mcp.tir118.000661] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Indexed: 01/03/2023] Open
Abstract
Although a variety of affinity purification mass spectrometry (AP-MS) strategies have been used to investigate complex interactions, many of these are susceptible to artifacts because of substantial overexpression of the exogenously expressed bait protein. Here we present a logical and systematic workflow that uses the multifunctional Halo tag to assess the correct localization and behavior of tagged subunits of the Sin3 histone deacetylase complex prior to further AP-MS analysis. Using this workflow, we modified our tagging/expression strategy with 21.7% of the tagged bait proteins that we constructed, allowing us to quickly develop validated reagents. Specifically, we apply the workflow to map interactions between stably expressed versions of the Sin3 subunits SUDS3, SAP30, or SAP30L and other cellular proteins. Here we show that the SAP30 and SAP30L paralogues strongly associate with the core Sin3 complex, but SAP30L has unique associations with the proteasome and the myelin sheath. Next, we demonstrate an advancement of the complex NSAF (cNSAF) approach, in which normalization to the scaffold protein SIN3A accounts for variations in the proportion of each bait capturing Sin3 complexes and allows a comparison among different baits capturing the same protein complex. This analysis reveals that although the Sin3 subunit SUDS3 appears to be used in both SIN3A and SIN3B based complexes, the SAP30 subunit is not used in SIN3B based complexes. Intriguingly, we do not detect the Sin3 subunits SAP18 and SAP25 among the 128 high-confidence interactions identified, suggesting that these subunits may not be common to all versions of the Sin3 complex in human cells. This workflow provides the framework for building validated reagents to assemble quantitative interaction networks for chromatin remodeling complexes and provides novel insights into focused protein interaction networks.
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Affiliation(s)
- Charles A S Banks
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Janet L Thornton
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | | | - Mark K Adams
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Sayem Miah
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Gina Boanca
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Xingyu Liu
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Maria L Katt
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Tari J Parmely
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Laurence Florens
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Michael P Washburn
- From the ‡Stowers Institute for Medical Research, Kansas City, MO 64110;
- §Departments of Pathology & Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS 66160
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30
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Wang Z, Ballut L, Barbosa I, Le Hir H. Exon Junction Complexes can have distinct functional flavours to regulate specific splicing events. Sci Rep 2018; 8:9509. [PMID: 29934576 PMCID: PMC6015020 DOI: 10.1038/s41598-018-27826-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 06/11/2018] [Indexed: 11/09/2022] Open
Abstract
The exon junction complex (EJC) deposited on spliced mRNAs, plays a central role in the post-transcriptional gene regulation and specific gene expression. The EJC core complex is associated with multiple peripheral factors involved in various post-splicing events. Here, using recombinant complex reconstitution and transcriptome-wide analysis, we showed that the EJC peripheral protein complexes ASAP and PSAP form distinct complexes with the EJC core and can confer to EJCs distinct alternative splicing regulatory activities. This study provides the first evidence that different EJCs can have distinct functions, illuminating EJC-dependent gene regulation.
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Affiliation(s)
- Zhen Wang
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, PSL Research University, Paris, F-75005, France
| | - Lionel Ballut
- Institut de Biologie et Chimie des Protéines, CNRS UMR5086, Université de Lyon 1, Lyon, France
| | - Isabelle Barbosa
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, PSL Research University, Paris, F-75005, France
| | - Hervé Le Hir
- Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, PSL Research University, Paris, F-75005, France.
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31
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Li L, Liu H, Hu X, Huang Y, Wang Y, He Y, Lei Q. Identification of key genes in non‑alcoholic fatty liver disease progression based on bioinformatics analysis. Mol Med Rep 2018; 17:7708-7720. [PMID: 29620197 PMCID: PMC5983972 DOI: 10.3892/mmr.2018.8852] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/22/2018] [Indexed: 12/18/2022] Open
Abstract
Due to economic development and lifestyle changes, the incidence of non-alcoholic fatty liver disease (NAFLD) has gradually increased in recent years. However, the pathogenesis of NAFLD is not yet fully understood. To identify candidate genes that contribute to the development and progression of NAFLD, two microarray datasets were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) were identified and functional enrichment analyses were performed. A protein-protein interaction network was constructed and modules were extracted using the Search Tool for the Retrieval of Interacting Genes and Cytoscape. The enriched functions and pathways of the DEGs included ‘cellular macromolecule biosynthetic process’, ‘cellular response to chemical stimulus’, ‘extracellular matrix organization’, ‘metabolic pathways’, ‘insulin resistance’ and ‘forkhead box protein O1 signaling pathway’. The DEGs, including type-1 angiotensin II receptor, formin-binding protein 1-like, RNA-binding protein with serine-rich domain 1, Ras-related C3 botulinum toxin substrate 1 and polyubiquitin-C, were identified using multiple bioinformatics methods and validated in vitro with reverse transcription-quantitative polymerase chain reaction analysis. In conclusion, five hub genes were identified in the present study, and they may aid in understanding of the molecular mechanisms underlying the development and progression of NAFLD.
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Affiliation(s)
- Lin Li
- Department of Liver Disease, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400021, P.R. China
| | - Huabao Liu
- Department of Liver Disease, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400021, P.R. China
| | - Xiaoyu Hu
- Department of Infectious Disease, Affiliated Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 610072, P.R. China
| | - Yi Huang
- Department of Liver Disease, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400021, P.R. China
| | - Yanan Wang
- Department of Liver Disease, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400021, P.R. China
| | - Yansha He
- Department of Liver Disease, Chongqing Traditional Chinese Medicine Hospital, Chongqing 400021, P.R. China
| | - Qingsong Lei
- Department of Infectious Disease, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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32
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Patchett AL, Wilson R, Charlesworth JC, Corcoran LM, Papenfuss AT, Lyons BA, Woods GM, Tovar C. Transcriptome and proteome profiling reveals stress-induced expression signatures of imiquimod-treated Tasmanian devil facial tumor disease (DFTD) cells. Oncotarget 2018; 9:15895-15914. [PMID: 29662615 PMCID: PMC5882306 DOI: 10.18632/oncotarget.24634] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/26/2018] [Indexed: 02/06/2023] Open
Abstract
As a topical cancer immunotherapy, the toll-like receptor 7 ligand imiquimod activates tumor regression via stimulation of immune cell infiltration and cytotoxic responses. Imiquimod also exerts direct pro-apoptotic effects on tumor cells in vitro, but a role for these effects in imiquimod-induced tumor regression remains undefined. We previously demonstrated that cell lines derived from devil facial tumor disease (DFTD), a transmissible cancer threatening the survival of the Tasmanian devil (Sarcophilus harrisii), are sensitive to imiquimod-induced apoptosis. In this study, the pro-apoptotic effects of imiquimod in DFTD have been investigated using RNA-sequencing and label-free quantitative proteomics. This analysis revealed that changes to gene and protein expression in imiquimod treated DFTD cells are consistent with the onset of oxidative and endoplasmic reticulum stress responses, and subsequent activation of the unfolded protein response, autophagy, cell cycle arrest and apoptosis. Imiquimod also regulates the expression of oncogenic pathways, providing a direct mechanism by which this drug may increase tumor susceptibility to immune cytotoxicity in vivo. Our study has provided the first global analysis of imiquimod-induced effects in any tumor cell line. These findings have highlighted the potential of cell stress pathways as therapeutic targets in DFTD, and will allow for improved mechanistic use of imiquimod as a therapy in both the Tasmanian devil and human cancers.
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Affiliation(s)
- Amanda L Patchett
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Richard Wilson
- Central Science Laboratory, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Jac C Charlesworth
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Lynn M Corcoran
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anthony T Papenfuss
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia.,Division of Cancer Research, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Victoria 3000, Australia
| | - Bruce A Lyons
- School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Gregory M Woods
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia.,School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Cesar Tovar
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7000, Australia
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33
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Fukumura K, Inoue K, Mayeda A. Splicing activator RNPS1 suppresses errors in pre-mRNA splicing: A key factor for mRNA quality control. Biochem Biophys Res Commun 2018; 496:921-926. [PMID: 29366779 DOI: 10.1016/j.bbrc.2018.01.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 01/18/2018] [Indexed: 02/06/2023]
Abstract
Human RNPS1 protein was first identified as a pre-mRNA splicing activator in vitro and RNPS1 regulates alternative splicing in cellulo. RNPS1 was also known as a peripheral factor of the exon junction complex (EJC). Here we show that cellular knockdown of RNPS1 induced a reduction of the wild-type aurora kinase B (AURKB) protein due to the induced aberrant pre-mRNA splicing events, indicating that the fidelity of AURKB pre-mRNA splicing was reduced. The major aberrant AURKB mRNA was derived from the upstream pseudo 5' and 3' splice sites in intron 5, which resulted in the production of the non-functional truncated AURKB protein. AURKB, is an essential mitotic factor, whose absence is known to cause multiple nuclei, and this multinucleation phenotype was recapitulated in RNPS1-knockdown cells. Importantly this RNPS1-knockdown phenotype was rescued by ectopic expression of AURKB, implying it is a major functional target of RNPS1. We found RNPS1 protein, not as a component of the EJC, binds directly to a specific element in the AURKB exon upstream of the authentic 5' splice site, and this binding is required for normal splicing. RNPS1-knockdown induces a parallel aberrant splicing pattern in a fully distinct pre-mRNA, MDM2, suggesting that RNPS1 is a global guardian of splicing fidelity. We conclude that RNPS1 is a key factor for the quality control of mRNAs that is essential for the phenotypes including cell division.
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Affiliation(s)
- Kazuhiro Fukumura
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake 470-1192, Aichi, Japan
| | - Kunio Inoue
- Department of Biology, Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Akila Mayeda
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake 470-1192, Aichi, Japan.
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34
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Nandi N, Tyra LK, Stenesen D, Krämer H. Stress-induced Cdk5 activity enhances cytoprotective basal autophagy in Drosophila melanogaster by phosphorylating acinus at serine 437. eLife 2017; 6:e30760. [PMID: 29227247 PMCID: PMC5760206 DOI: 10.7554/elife.30760] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/08/2017] [Indexed: 12/22/2022] Open
Abstract
Cdk5 is a post-mitotic kinase with complex roles in maintaining neuronal health. The various mechanisms by which Cdk5 inhibits and promotes neurodegeneration are still poorly understood. Here, we show that in Drosophila melanogaster Cdk5 regulates basal autophagy, a key mechanism suppressing neurodegeneration. In a targeted screen, Cdk5 genetically interacted with Acinus (Acn), a primarily nuclear protein, which promotes starvation-independent, basal autophagy. Loss of Cdk5, or its required cofactor p35, reduces S437-Acn phosphorylation, whereas Cdk5 gain-of-function increases pS437-Acn levels. The phospho-mimetic S437D mutation stabilizes Acn and promotes basal autophagy. In p35 mutants, basal autophagy and lifespan are reduced, but restored to near wild-type levels in the presence of stabilized AcnS437D. Expression of aggregation-prone polyQ-containing proteins or the Amyloid-β42 peptide, but not alpha-Synuclein, enhances Cdk5-dependent phosphorylation of S437-Acn. Our data indicate that Cdk5 is required to maintain the protective role of basal autophagy in the initial responses to a subset of neurodegenerative challenges.
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Affiliation(s)
- Nilay Nandi
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Lauren K Tyra
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Drew Stenesen
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Helmut Krämer
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
- Department of Cell BiologyUT Southwestern Medical CenterDallasUnited States
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35
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Wang ZH, Liu P, Liu X, Manfredsson FP, Sandoval IM, Yu SP, Wang JZ, Ye K. Delta-Secretase Phosphorylation by SRPK2 Enhances Its Enzymatic Activity, Provoking Pathogenesis in Alzheimer's Disease. Mol Cell 2017; 67:812-825.e5. [PMID: 28826672 DOI: 10.1016/j.molcel.2017.07.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 06/28/2017] [Accepted: 07/19/2017] [Indexed: 01/06/2023]
Abstract
Delta-secretase, a lysosomal asparagine endopeptidase (AEP), simultaneously cleaves both APP and tau, controlling the onset of pathogenesis of Alzheimer's disease (AD). However, how this protease is post-translationally regulated remains unclear. Here we report that serine-arginine protein kinase 2 (SRPK2) phosphorylates delta-secretase and enhances its enzymatic activity. SRPK2 phosphorylates serine 226 on delta-secretase and accelerates its autocatalytic cleavage, leading to its cytoplasmic translocation and escalated enzymatic activities. Delta-secretase is highly phosphorylated in human AD brains, tightly correlated with SRPK2 activity. Overexpression of a phosphorylation mimetic (S226D) in young 3xTg mice strongly promotes APP and tau fragmentation and facilitates amyloid plaque deposits and neurofibrillary tangle (NFT) formation, resulting in cognitive impairment. Conversely, viral injection of the non-phosphorylatable mutant (S226A) into 5XFAD mice decreases APP and tau proteolytic cleavage, attenuates AD pathologies, and reverses cognitive defects. Our findings support that delta-secretase phosphorylation by SRPK2 plays a critical role in aggravating AD pathogenesis.
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Affiliation(s)
- Zhi-Hao Wang
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Pathophysiology, Key Laboratory of Ministry of Education of Neurological Diseases, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Pai Liu
- Emory College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Xia Liu
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Fredric P Manfredsson
- Department of Translational Science and Molecular Medicine, Michigan State University, 333 Bostwick Avenue NE, Grand Rapids, MI 49503, USA
| | - Ivette M Sandoval
- Department of Translational Science and Molecular Medicine, Michigan State University, 333 Bostwick Avenue NE, Grand Rapids, MI 49503, USA
| | - Shan Ping Yu
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jian-Zhi Wang
- Department of Pathophysiology, Key Laboratory of Ministry of Education of Neurological Diseases, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Co-innovation Center of Neuroregeneration, Nantong 226001, China.
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA; Translational Center for Stem Cell Research, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China.
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36
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Deka B, Singh KK. Multifaceted Regulation of Gene Expression by the Apoptosis- and Splicing-Associated Protein Complex and Its Components. Int J Biol Sci 2017; 13:545-560. [PMID: 28539829 PMCID: PMC5441173 DOI: 10.7150/ijbs.18649] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/24/2017] [Indexed: 11/24/2022] Open
Abstract
The differential deposition of RNA-binding proteins (RBPs) on pre-mRNA mediates the processes of gene expression. One of the complexes containing RBPs that play a crucial part in RNA metabolism is the apoptosis-and splicing-associated protein (ASAP) complex. In this review, we present a summary of the structure of ASAP complex and its localization. Also, we discuss the findings by different groups on various functions of the subunits of the ASAP complex in RNA metabolism. The subunits of the ASAP complex are RNPS1, Acinus and SAP18. Originally, the ASAP complex was thought to link RNA processing with apoptosis. Further studies have shown the role of these components in RNA metabolism of cells, including transcription, splicing, translation and nonsense-mediated mRNA decay (NMD). In transcription, RNPS1 is involved in preventing the formation of R-loop, while Acinus and SAP18 suppress transcription with the help of histone deacetylase. On the one hand, individual components of the ASAP complex, namely RNPS1 and Acinus act as splicing activators, whereas on the other hand, in-vitro assay shows that the ASAP complex behaves as splicing repressor. In addition, the individual members of the ASAP complex associates with the exon junction complex (EJC) to play roles in splicing and translation. RNPS1 increases the translation efficiency by participating in the 3'end processing and polysome association of mRNAs. Similarly, during NMD RNPS1 aids in the recruitment of decay factors by interacting with EJC.
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Affiliation(s)
| | - Kusum Kumari Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India
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37
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Alternative Splicing in Plant Genes: A Means of Regulating the Environmental Fitness of Plants. Int J Mol Sci 2017; 18:ijms18020432. [PMID: 28230724 PMCID: PMC5343966 DOI: 10.3390/ijms18020432] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Revised: 02/04/2017] [Accepted: 02/10/2017] [Indexed: 01/01/2023] Open
Abstract
Gene expression can be regulated through transcriptional and post-transcriptional mechanisms. Transcription in eukaryotes produces pre-mRNA molecules, which are processed and spliced post-transcriptionally to create translatable mRNAs. More than one mRNA may be produced from a single pre-mRNA by alternative splicing (AS); thus, AS serves to diversify an organism’s transcriptome and proteome. Previous studies of gene expression in plants have focused on the role of transcriptional regulation in response to environmental changes. However, recent data suggest that post-transcriptional regulation, especially AS, is necessary for plants to adapt to a changing environment. In this review, we summarize recent advances in our understanding of AS during plant development in response to environmental changes. We suggest that alternative gene splicing is a novel means of regulating the environmental fitness of plants.
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38
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Export of piRNA precursors by EJC triggers assembly of cytoplasmic Yb-body in Drosophila. Nat Commun 2016; 7:13739. [PMID: 27929060 PMCID: PMC5155165 DOI: 10.1038/ncomms13739] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 10/28/2016] [Indexed: 01/04/2023] Open
Abstract
PIWI-interacting RNAs (piRNAs) are effectors of transposable element (TE) silencing in the reproductive apparatus. In Drosophila ovarian somatic cells, piRNAs arise from longer single-stranded RNA precursors that are processed in the cytoplasm presumably within the Yb-bodies. piRNA precursors encoded by the flamenco (flam) piRNA cluster accumulate in a single focus away from their sites of transcription. In this study, we identify the exportin complex containing Nxf1 and Nxt1 as required for flam precursor nuclear export. Together with components of the exon junction complex (EJC), it is necessary for the efficient transfer of flam precursors away from their site of transcription. Indeed, depletion of these components greatly affects flam intra-nuclear transit. Moreover, we show that Yb-body assembly is dependent on the nucleo-cytoplasmic export of flam transcripts. These results suggest that somatic piRNA precursors are thus required for the assembly of the cytoplasmic transposon silencing machinery.
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39
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Burton LJ, Rivera M, Hawsawi O, Zou J, Hudson T, Wang G, Zhang Q, Cubano L, Boukli N, Odero-Marah V. Muscadine Grape Skin Extract Induces an Unfolded Protein Response-Mediated Autophagy in Prostate Cancer Cells: A TMT-Based Quantitative Proteomic Analysis. PLoS One 2016; 11:e0164115. [PMID: 27755556 PMCID: PMC5068743 DOI: 10.1371/journal.pone.0164115] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/19/2016] [Indexed: 01/06/2023] Open
Abstract
Muscadine grape skin extract (MSKE) is derived from muscadine grape (Vitis rotundifolia), a common red grape used to produce red wine. Endoplasmic reticulum (ER) stress activates the unfolded protein response (UPR) that serves as a survival mechanism to relieve ER stress and restore ER homeostasis. However, when persistent, ER stress can alter the cytoprotective functions of the UPR to promote autophagy and cell death. Although MSKE has been documented to induce apoptosis, it has not been linked to ER stress/UPR/autophagy. We hypothesized that MSKE may induce a severe ER stress response-mediated autophagy leading to apoptosis. As a model, we treated C4-2 prostate cancer cells with MSKE and performed a quantitative Tandem Mass Tag Isobaric Labeling proteomic analysis. ER stress response, autophagy and apoptosis were analyzed by western blot, acridine orange and TUNEL/Annexin V staining, respectively. Quantitative proteomics analysis indicated that ER stress response proteins, such as GRP78 were greatly elevated following treatment with MSKE. The up-regulation of pro-apoptotic markers PARP, caspase-12, cleaved caspase-3, -7, BAX and down-regulation of anti-apoptotic marker BCL2 was confirmed by Western blot analysis and apoptosis was visualized by increased TUNEL/Annexin V staining upon MSKE treatment. Moreover, increased acridine orange, and LC3B staining was detected in MSKE-treated cells, suggesting an ER stress/autophagy response. Finally, MSKE-mediated autophagy and apoptosis was antagonized by co-treatment with chloroquine, an autophagy inhibitor. Our results indicate that MSKE can elicit an UPR that can eventually lead to apoptosis in prostate cancer cells.
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Affiliation(s)
- Liza J. Burton
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America
| | - Mariela Rivera
- Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamon, PR, 00956, United States of America
| | - Ohuod Hawsawi
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America
| | - Jin Zou
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America
| | - Tamaro Hudson
- Department of Medicine, Howard University, Washington, DC, 20060, United States of America
| | - Guangdi Wang
- Department of Chemistry, Xavier University, New Orleans, LA, 70125, United States of America
| | - Qiang Zhang
- Department of Chemistry, Xavier University, New Orleans, LA, 70125, United States of America
| | - Luis Cubano
- Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamon, PR, 00956, United States of America
| | - Nawal Boukli
- Department of Microbiology and Immunology, School of Medicine, Universidad Central del Caribe, Bayamon, PR, 00956, United States of America
| | - Valerie Odero-Marah
- Center for Cancer Research and Therapeutic Development, Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, 30314, United States of America
- * E-mail:
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Boehm V, Gehring NH. Exon Junction Complexes: Supervising the Gene Expression Assembly Line. Trends Genet 2016; 32:724-735. [PMID: 27667727 DOI: 10.1016/j.tig.2016.09.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 08/23/2016] [Accepted: 09/01/2016] [Indexed: 12/16/2022]
Abstract
The exon junction complex (EJC) is an RNA-binding protein complex that is assembled and deposited onto mRNAs during splicing. The EJC comprises four core components that bind to not only canonical sites upstream of exon-exon junctions, but also to noncanonical sites at other positions in exons. EJC-associated proteins are recruited by the EJC at different steps of gene expression to execute the multiple functions of the EJC. Recently, new insights have been obtained into how EJCs stimulate pre-mRNA splicing, and mRNA export, translation, and degradation. Furthermore, mutations in EJC core components were shown to result in severe disorders in humans, demonstrating the critical physiological role of the EJC. Hence, the EJC has been identified as an important player in post-transcriptional gene regulation in metazoans.
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Affiliation(s)
- Volker Boehm
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany.
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Rodor J, Pan Q, Blencowe BJ, Eyras E, Cáceres JF. The RNA-binding profile of Acinus, a peripheral component of the exon junction complex, reveals its role in splicing regulation. RNA (NEW YORK, N.Y.) 2016; 22:1411-26. [PMID: 27365209 PMCID: PMC4986896 DOI: 10.1261/rna.057158.116] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/24/2016] [Indexed: 05/21/2023]
Abstract
Acinus (apoptotic chromatin condensation inducer in the nucleus) is an RNA-binding protein (RBP) originally identified for its role in apoptosis. It was later found to be an auxiliary component of the exon junction complex (EJC), which is deposited at exon junctions as a consequence of pre-mRNA splicing. To uncover the cellular functions of Acinus and investigate its role in splicing, we mapped its endogenous RNA targets using the cross-linking immunoprecipitation protocol (iCLIP). We observed that Acinus binds to pre-mRNAs, associating specifically to a subset of suboptimal introns, but also to spliced mRNAs. We also confirmed the presence of Acinus as a peripheral factor of the EJC. RNA-seq was used to investigate changes in gene expression and alternative splicing following siRNA-mediated depletion of Acinus in HeLa cells. This analysis revealed that Acinus is preferentially required for the inclusion of specific alternative cassette exons and also controls the faithful splicing of a subset of introns. Moreover, a large number of splicing changes can be related to Acinus binding, suggesting a direct role of Acinus in exon and intron definition. In particular, Acinus regulates the splicing of DFFA/ICAD transcript, a major regulator of DNA fragmentation. Globally, the genome-wide identification of RNA targets of Acinus revealed its role in splicing regulation as well as its involvement in other cellular pathways, including cell cycle progression. Altogether, this study uncovers new cellular functions of an RBP transiently associated with the EJC.
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Affiliation(s)
- Julie Rodor
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Qun Pan
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Benjamin J Blencowe
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Eduardo Eyras
- Universitat Pompeu Fabra, E08003, Barcelona, Spain Catalan Institution for Research and Advanced Studies (ICREA), E08010 Barcelona, Spain
| | - Javier F Cáceres
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
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The Exon Junction Complex Controls the Efficient and Faithful Splicing of a Subset of Transcripts Involved in Mitotic Cell-Cycle Progression. Int J Mol Sci 2016; 17:ijms17081153. [PMID: 27490541 PMCID: PMC5000587 DOI: 10.3390/ijms17081153] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 01/13/2023] Open
Abstract
The exon junction complex (EJC) that is deposited onto spliced mRNAs upstream of exon–exon junctions plays important roles in multiple post-splicing gene expression events, such as mRNA export, surveillance, localization, and translation. However, a direct role for the human EJC in pre-mRNA splicing has not been fully understood. Using HeLa cells, we depleted one of the EJC core components, Y14, and the resulting transcriptome was analyzed by deep sequencing (RNA-Seq) and confirmed by RT–PCR. We found that Y14 is required for efficient and faithful splicing of a group of transcripts that is enriched in short intron-containing genes involved in mitotic cell-cycle progression. Tethering of EJC core components (Y14, eIF4AIII or MAGOH) to a model reporter pre-mRNA harboring a short intron showed that these core components are prerequisites for the splicing activation. Taken together, we conclude that the EJC core assembled on pre-mRNA is critical for efficient and faithful splicing of a specific subset of short introns in mitotic cell cycle-related genes.
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43
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Qüesta JI, Song J, Geraldo N, An H, Dean C. Arabidopsis
transcriptional repressor VAL1 triggers Polycomb silencing at
FLC
during vernalization. Science 2016; 353:485-8. [DOI: 10.1126/science.aaf7354] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 07/01/2016] [Indexed: 12/17/2022]
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Hir HL, Saulière J, Wang Z. The exon junction complex as a node of post-transcriptional networks. Nat Rev Mol Cell Biol 2015; 17:41-54. [DOI: 10.1038/nrm.2015.7] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Prokhorova EA, Zamaraev AV, Kopeina GS, Zhivotovsky B, Lavrik IN. Role of the nucleus in apoptosis: signaling and execution. Cell Mol Life Sci 2015; 72:4593-612. [PMID: 26346492 PMCID: PMC11113907 DOI: 10.1007/s00018-015-2031-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 08/06/2015] [Accepted: 08/27/2015] [Indexed: 02/06/2023]
Abstract
Since their establishment in the early 1970s, the nuclear changes upon apoptosis induction, such as the condensation of chromatin, disassembly of nuclear scaffold proteins and degradation of DNA, were, and still are, considered as the essential steps and hallmarks of apoptosis. These are the characteristics of the execution phase of apoptotic cell death. In addition, accumulating data clearly show that some nuclear events can lead to the induction of apoptosis. In particular, if DNA lesions resulting from deregulation during the cell cycle or DNA damage induced by chemotherapeutic drugs or viral infection cannot be efficiently eliminated, apoptotic mechanisms, which enable cellular transformation to be avoided, are activated in the nucleus. The functional heterogeneity of the nuclear organization allows the tight regulation of these signaling events that involve the movement of various nuclear proteins to other intracellular compartments (and vice versa) to initiate and govern apoptosis. Here, we discuss how these events are coordinated to execute apoptotic cell death.
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Affiliation(s)
- Evgeniia A Prokhorova
- Faculty of Basic Medicine, MV Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Alexey V Zamaraev
- Faculty of Basic Medicine, MV Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Gelina S Kopeina
- Faculty of Basic Medicine, MV Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Boris Zhivotovsky
- Faculty of Basic Medicine, MV Lomonosov Moscow State University, Moscow, 119991, Russia.
- Division of Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, 17177, Stockholm, Sweden.
| | - Inna N Lavrik
- Faculty of Basic Medicine, MV Lomonosov Moscow State University, Moscow, 119991, Russia
- Department of Translational Inflammation, Institute of Experimental Internal Medicine, Otto von Guericke University, Magdeburg, Germany
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46
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Pineda G, Shen Z, de Albuquerque CP, Reynoso E, Chen J, Tu CC, Tang W, Briggs S, Zhou H, Wang JYJ. Proteomics studies of the interactome of RNA polymerase II C-terminal repeated domain. BMC Res Notes 2015; 8:616. [PMID: 26515650 PMCID: PMC4627417 DOI: 10.1186/s13104-015-1569-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 10/07/2015] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Eukaryotic RNA polymerase II contains a C-terminal repeated domain (CTD) consisting of 52 consensus heptad repeats of Y1S2P3T4S5P6S7 that mediate interactions with many cellular proteins to regulate transcription elongation, RNA processing and chromatin structure. A number of CTD-binding proteins have been identified and the crystal structures of several protein-CTD complexes have demonstrated considerable conformational flexibility of the heptad repeats in those interactions. Furthermore, phosphorylation of the CTD at tyrosine, serine and threonine residues can regulate the CTD-protein interactions. Although the interactions of CTD with specific proteins have been elucidated at the atomic level, the capacity and specificity of the CTD-interactome in mammalian cells is not yet determined. RESULTS A proteomic study was conducted to examine the mammalian CTD-interactome. We utilized six synthetic peptides each consisting of four consensus CTD-repeats with different combinations of serine and tyrosine phosphorylation as affinity-probes to pull-down nuclear proteins from HeLa cells. The pull-down fractions were then analyzed by MUDPIT mass spectrometry, which identified 100 proteins with the majority from the phospho-CTD pull-downs. Proteins pulled-down by serine-phosphorylated CTD-peptides included those containing the previously defined CTD-interacting domain (CID). Using SILAC mass spectrometry, we showed that the in vivo interaction of RNA polymerase II with the mammalian CID-containing RPRD1B is disrupted by CID mutation. We also showed that the CID from four mammalian proteins interacted with pS2-phosphorylated but not pY1pS2-doubly phosphorylated CTD-peptides. However, we also found proteins that were preferentially pulled-down by pY1pS2- or pY1pS5-doubly phosphorylated CTD-peptides. We prepared an antibody against tyrosine phosphorylated CTD and showed that ionizing radiation (IR) induced a transient increase in CTD tyrosine phosphorylation by immunoblotting. Combining SILAC and IMAC purification of phospho-peptides, we found that IR regulated the phosphorylation at four CTD tyrosine sites in different ways. CONCLUSION Upon phosphorylation, the 52 repeats of the CTD have the capacity to generate a large number of binding sites for cellular proteins. This study confirms previous findings that serine phosphorylation stimulates whereas tyrosine phosphorylation inhibits the protein-binding activity of the CTD. However, tyrosine phosphorylation of the CTD can also stimulate other CTD-protein interactions. The CTD-peptide affinity pull-down method described here can be adopted to survey the mammalian CTD-interactome in various cell types and under different biological conditions.
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Affiliation(s)
- Gabriel Pineda
- Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Department of Medicine, Division of Hematology-Oncology, University of California, San Diego, George Palade Laboratories Room 256, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Zhouxin Shen
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Claudio Ponte de Albuquerque
- Ludwig Institute for Cancer Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Department of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Eduardo Reynoso
- Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Jeffrey Chen
- Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Chi-Chiang Tu
- Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Wingchung Tang
- Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Steve Briggs
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Huilin Zhou
- Ludwig Institute for Cancer Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Department of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - Jean Y J Wang
- Moores Cancer Center, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Department of Medicine, Division of Hematology-Oncology, University of California, San Diego, George Palade Laboratories Room 256, 9500 Gilman Drive, La Jolla, CA, 92093, USA. .,Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
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Wang F, Wendling KS, Soprano KJ, Soprano DR. The SAP motif and C-terminal RS- and RD/E-rich region influences the sub-nuclear localization of Acinus isoforms. J Cell Biochem 2015; 115:2165-74. [PMID: 25079509 DOI: 10.1002/jcb.24893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 07/25/2014] [Indexed: 11/06/2022]
Abstract
Acinus has been reported to function in apoptosis, RNA processing and regulation of gene transcription including RA-dependent transcription. There are three different isoforms of Acinus termed Acinus-L, Acinus-S', and Acinus-S. The isoforms of Acinus differ in their N-terminus while the C-terminus is consistent in all isoforms. The sub-nuclear localization of Acinus-L and Acinus-S' was determined using fluorescence microscopy. Acinus-S' colocalizes with SC35 in nuclear speckles while Acinus-L localizes diffusely throughout the nucleoplasm. RA treatment has little effect on the sub-nuclear localization of Acinus-L and Acinus-S'. The domains/regions necessary for the distinct sub-nuclear localization of Acinus-L and Acinus-S' were identified. The speckled sub-nuclear localization of Acinus-S' is dependent on its C-terminal RS- and RD/E-rich region but is independent of the phosphorylation status of Ser-453 and Ser-604 within this region. The unique N-terminal SAP motif of Acinus-L is responsible for its diffuse localization in the nucleus. Moreover, the sub-nuclear localization of Acinus isoforms is affected by each other, which is determined by the combinatorial effect of the more potent SAP motif of Acinus-L and the C-terminal RS- and RD/E-rich region in all Acinus isoforms. The C-terminal RS- and RD/E-rich region of Acinus mediates the colocalization of Acinus isoforms as well as with its interacting protein RNPS1. In conclusion, the SAP motif is responsible for the difference in the nuclear localization between Acinus-L and Acinus-S'. This difference in the nuclear localization of Acinus-S' and Acinus-L may suggest that these two isoforms have different functional roles.
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Affiliation(s)
- Fang Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
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Schwarz JJ, Wiese H, Tölle RC, Zarei M, Dengjel J, Warscheid B, Thedieck K. Functional Proteomics Identifies Acinus L as a Direct Insulin- and Amino Acid-Dependent Mammalian Target of Rapamycin Complex 1 (mTORC1) Substrate. Mol Cell Proteomics 2015; 14:2042-55. [PMID: 25907765 DOI: 10.1074/mcp.m114.045807] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Indexed: 12/31/2022] Open
Abstract
The serine/threonine kinase mammalian target of rapamycin (mTOR) governs growth, metabolism, and aging in response to insulin and amino acids (aa), and is often activated in metabolic disorders and cancer. Much is known about the regulatory signaling network that encompasses mTOR, but surprisingly few direct mTOR substrates have been established to date. To tackle this gap in our knowledge, we took advantage of a combined quantitative phosphoproteomic and interactomic strategy. We analyzed the insulin- and aa-responsive phosphoproteome upon inhibition of the mTOR complex 1 (mTORC1) component raptor, and investigated in parallel the interactome of endogenous mTOR. By overlaying these two datasets, we identified acinus L as a potential novel mTORC1 target. We confirmed acinus L as a direct mTORC1 substrate by co-immunoprecipitation and MS-enhanced kinase assays. Our study delineates a triple proteomics strategy of combined phosphoproteomics, interactomics, and MS-enhanced kinase assays for the de novo-identification of mTOR network components, and provides a rich source of potential novel mTOR interactors and targets for future investigation.
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Affiliation(s)
- Jennifer Jasmin Schwarz
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg
| | - Heike Wiese
- §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany
| | - Regine Charlotte Tölle
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany
| | - Mostafa Zarei
- ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Jörn Dengjel
- ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg; ‖Department of Dermatology, Medical Center, and Centre for Biological Systems Analysis (ZBSA), University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bettina Warscheid
- §Faculty of Biology, Institute of Biology II, University of Freiburg, 79104 Freiburg, Germany; ¶Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany;
| | - Kathrin Thedieck
- From the ‡Faculty of Biology, Institute of Biology III, University of Freiburg, 79104 Freiburg, Germany; **BIOSS Centre for Biological Signaling Studies, University of Freiburg, 79104 Freiburg, Germany; ‡‡Department of Pediatrics, University of Groningen, University Medical Center Groningen (UMCG), 9713 AV Groningen, The Netherlands; §§Department for Neurosciences, Faculty VI - School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany
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49
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Wang F, Soprano KJ, Soprano DR. Role of Acinus in regulating retinoic acid-responsive gene pre-mRNA splicing. J Cell Physiol 2015; 230:791-801. [PMID: 25205379 DOI: 10.1002/jcp.24804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Accepted: 09/05/2014] [Indexed: 02/03/2023]
Abstract
Acinus-S' is a corepressor for retinoic acid receptor (RAR)-dependent gene transcription and has been suggested to be involved in RNA processing. In this study, the role of Acinus isoforms in regulating pre-mRNA splicing was explored using in vivo splicing assays. Both Acinus-L and Acinus-S', with the activity of Acinus-L higher than that of Acinus-S', increase the splicing of a retinoic acid (RA)-responsive minigene containing a weak 5' splice site but not a RA-responsive minigene containing a strong 5' splice site. RA treatment further enhances the splicing of the weak 5' splice site by Acinus in a dose- and time-dependent manner, suggesting a RA-dependent activity in addition to a RA-independent activity of Acinus. The RA-independent effect of Acinus occurs to varying degrees using minigene constructs containing several different promoters, while the RA-dependent splicing activity of Acinus is specific for transcripts derived from the minigene driven by a RA response element (RARE)-containing promoter. This suggests that the ligand-dependent splicing activity of Acinus is related to the RA-activated RAR bound to the RARE. The RRM domain is necessary for the RA-dependent splicing activity of Acinus and the RA-independent splicing activity of Acinus is repressed by RNPS1. Importantly, measurement of the splicing of endogenous human RARβ and Bcl-x in vivo demonstrates that Acinus stimulates the use of the weaker alternative 5' splice site of these two genes in a RA-dependent manner for RARβ and a RA-independent manner for Bcl-x. Taken together, these studies demonstrate that Acinus functions in both RAR-dependent splicing and RAR-dependent transcription.
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Affiliation(s)
- Fang Wang
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA
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50
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Nandi N, Tyra LK, Stenesen D, Krämer H. Acinus integrates AKT1 and subapoptotic caspase activities to regulate basal autophagy. ACTA ACUST UNITED AC 2014; 207:253-68. [PMID: 25332163 PMCID: PMC4210446 DOI: 10.1083/jcb.201404028] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
How cellular stresses up-regulate autophagy is not fully understood. One potential regulator is the Drosophila melanogaster protein Acinus (Acn), which is necessary for autophagy induction and triggers excess autophagy when overexpressed. We show that cell type-specific regulation of Acn depends on proteolysis by the caspase Dcp-1. Basal Dcp-1 activity in developing photoreceptors is sufficient for this cleavage without a need for apoptosis to elevate caspase activity. On the other hand, Acn was stabilized by loss of Dcp-1 function or by the presence of a mutation in Acn that eliminates its conserved caspase cleavage site. Acn stability also was regulated by AKT1-mediated phosphorylation. Flies that expressed stabilized forms of Acn, either the phosphomimetic Acn(S641,731D) or the caspase-resistant Acn(D527A), exhibited enhanced basal autophagy. Physiologically, these flies showed improvements in processes known to be autophagy dependent, including increased starvation resistance, reduced Huntingtin-induced neurodegeneration, and prolonged life span. These data indicate that AKT1 and caspase-dependent regulation of Acn stability adjusts basal autophagy levels.
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Affiliation(s)
- Nilay Nandi
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lauren K Tyra
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Drew Stenesen
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Helmut Krämer
- Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390 Department of Neuroscience and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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