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Jiang Y, Adhikari D, Li C, Zhou X. Spatiotemporal regulation of maternal mRNAs during vertebrate oocyte meiotic maturation. Biol Rev Camb Philos Soc 2023; 98:900-930. [PMID: 36718948 DOI: 10.1111/brv.12937] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 01/15/2023] [Accepted: 01/17/2023] [Indexed: 02/01/2023]
Abstract
Vertebrate oocytes face a particular challenge concerning the regulation of gene expression during meiotic maturation. Global transcription becomes quiescent in fully grown oocytes, remains halted throughout maturation and fertilization, and only resumes upon embryonic genome activation. Hence, the oocyte meiotic maturation process is largely regulated by protein synthesis from pre-existing maternal messenger RNAs (mRNAs) that are transcribed and stored during oocyte growth. Rapidly developing genome-wide techniques have greatly expanded our insights into the global translation changes and possible regulatory mechanisms during oocyte maturation. The storage, translation, and processing of maternal mRNAs are thought to be regulated by factors interacting with elements in the mRNA molecules. Additionally, posttranscriptional modifications of mRNAs, such as methylation and uridylation, have recently been demonstrated to play crucial roles in maternal mRNA destabilization. However, a comprehensive understanding of the machineries that regulate maternal mRNA fate during oocyte maturation is still lacking. In particular, how the transcripts of important cell cycle components are stabilized, recruited at the appropriate time for translation, and eliminated to modulate oocyte meiotic progression remains unclear. A better understanding of these mechanisms will provide invaluable insights for the preconditions of developmental competence acquisition, with important implications for the treatment of infertility. This review discusses how the storage, localization, translation, and processing of oocyte mRNAs are regulated, and how these contribute to oocyte maturation progression.
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Affiliation(s)
- Yanwen Jiang
- College of Animal Science, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Deepak Adhikari
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, 19 Innovation Walk, Melbourne, VIC, 3800, Australia
| | - Chunjin Li
- College of Animal Science, Jilin University, 5333 Xian Road, Changchun, 130062, China
| | - Xu Zhou
- College of Animal Science, Jilin University, 5333 Xian Road, Changchun, 130062, China
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2
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Dong Z, Qian J, Law TSM, Chau MHK, Cao Y, Xue S, Tong S, Zhao Y, Kwok YK, Ng K, Chan DYL, Chiu PKF, Ng CF, Chung CHS, Mak JSM, Leung TY, Chung JPW, Morton CC, Choy KW. Mate-pair genome sequencing reveals structural variants for idiopathic male infertility. Hum Genet 2023; 142:363-377. [PMID: 36526900 DOI: 10.1007/s00439-022-02510-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022]
Abstract
Currently, routine genetic investigation for male infertility includes karyotyping analysis and PCR for Y chromosomal microdeletions to provide prognostic information such as sperm retrieval success rate. However, over 85% of male infertility remain idiopathic. We assessed 101 male patients with primary infertility in a retrospective cohort analysis who have previously received negative results from standard-of-care tests. Mate-pair genome sequencing (large-insert size library), an alternative long-DNA sequencing method, was performed to detect clinically significant structural variants (SVs) and copy-number neutral absence of heterozygosity (AOH). Candidate SVs were filtered against our in-house cohort of 1077 fertile men. Genes disrupted by potentially clinically significant variants were correlated with single-cell gene expression profiles of human fetal and postnatal testicular developmental lineages and adult germ cells. Follow-up studies were conducted for each patient with clinically relevant finding(s). Molecular diagnoses were made in 11.1% (7/63) of patients with non-obstructive azoospermia and 13.2% (5/38) of patients with severe oligozoospermia. Among them, 12 clinically significant SVs were identified in 12 cases, including five known syndromes, one inversion, and six SVs with direct disruption of genes by intragenic rearrangements or complex insertions. Importantly, a genetic defect related to intracytoplasmic sperm injection (ICSI) failure was identified in a patient with non-obstructive azoospermia, illustrating the additional value of an etiologic diagnosis in addition to determining sperm retrieval rate. Our study reveals a landscape of various genomic variants in 101 males with idiopathic infertility, not only advancing understanding of the underlying mechanisms of male infertility, but also impacting clinical management.
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Affiliation(s)
- Zirui Dong
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China. .,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China. .,Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China. .,The Fertility Preservation Research Center, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.
| | - Jicheng Qian
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China
| | - Tracy Sze Man Law
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China
| | - Matthew Hoi Kin Chau
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China.,Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China.,The Chinese University of Hong Kong-Baylor College of Medicine Joint Center for Medical Genetics, Hong Kong, China
| | - Ye Cao
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China.,Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China.,The Fertility Preservation Research Center, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Shuwen Xue
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China
| | - Steve Tong
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Yilin Zhao
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Yvonne K Kwok
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Karen Ng
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - David Yiu Leung Chan
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Peter K-F Chiu
- SH Ho Urology Centre, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Chi-Fai Ng
- SH Ho Urology Centre, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Cathy Hoi Sze Chung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Jennifer Sze Man Mak
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China
| | - Tak Yeung Leung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China.,The Fertility Preservation Research Center, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,The Chinese University of Hong Kong-Baylor College of Medicine Joint Center for Medical Genetics, Hong Kong, China
| | - Jacqueline Pui Wah Chung
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China.,The Fertility Preservation Research Center, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China.,The Chinese University of Hong Kong-Baylor College of Medicine Joint Center for Medical Genetics, Hong Kong, China
| | - Cynthia C Morton
- Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Boston, MA, 02115, USA.,Department of Pathology, Brigham and Women's Hospital, Boston, MA, 02115, USA.,Harvard Medical School, Boston, MA, 02115, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.,Manchester Centre for Audiology and Deafness, School of Health Sciences, University of Manchester, Manchester, M13 9PL, UK
| | - Kwong Wai Choy
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China. .,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057, China. .,Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China. .,The Fertility Preservation Research Center, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, China. .,The Chinese University of Hong Kong-Baylor College of Medicine Joint Center for Medical Genetics, Hong Kong, China.
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3
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Ozturk S. Molecular determinants of the meiotic arrests in mammalian oocytes at different stages of maturation. Cell Cycle 2022; 21:547-571. [PMID: 35072590 PMCID: PMC8942507 DOI: 10.1080/15384101.2022.2026704] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/21/2021] [Accepted: 01/03/2022] [Indexed: 01/26/2023] Open
Abstract
Mammalian oocytes undergo two rounds of developmental arrest during maturation: at the diplotene of the first meiotic prophase and metaphase of the second meiosis. These arrests are strictly regulated by follicular cells temporally producing the secondary messengers, cAMP and cGMP, and other factors to regulate maturation promoting factor (composed of cyclin B1 and cyclin-dependent kinase 1) levels in the oocytes. Out of these normally appearing developmental arrests, permanent arrests may occur in the oocytes at germinal vesicle (GV), metaphase I (MI), or metaphase II (MII) stage. This issue may arise from absence or altered expression of the oocyte-related genes playing key roles in nuclear and cytoplasmic maturation. Additionally, the assisted reproductive technology (ART) applications such as ovarian stimulation and in vitro culture conditions both of which harbor various types of chemical agents may contribute to forming the permanent arrests. In this review, the molecular determinants of developmental and permanent arrests occurring in the mammalian oocytes are comprehensively evaluated in the light of current knowledge. As number of permanently arrested oocytes at different stages is increasing in ART centers, potential approaches for inducing permanent arrests to obtain competent oocytes are discussed.
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Affiliation(s)
- Saffet Ozturk
- Department of Histology and Embryology, Akdeniz University School of Medicine, Antalya, Turkey
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4
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Nourreddine S, Lavoie G, Paradis J, Ben El Kadhi K, Méant A, Aubert L, Grondin B, Gendron P, Chabot B, Bouvier M, Carreno S, Roux PP. NF45 and NF90 Regulate Mitotic Gene Expression by Competing with Staufen-Mediated mRNA Decay. Cell Rep 2021; 31:107660. [PMID: 32433969 DOI: 10.1016/j.celrep.2020.107660] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 01/16/2020] [Accepted: 04/28/2020] [Indexed: 12/12/2022] Open
Abstract
In human cells, the expression of ∼1,000 genes is modulated throughout the cell cycle. Although some of these genes are controlled by specific transcriptional programs, very little is known about their post-transcriptional regulation. Here, we analyze the expression signature associated with all 687 RNA-binding proteins (RBPs) and identify 39 that significantly correlate with cell cycle mRNAs. We find that NF45 and NF90 play essential roles in mitosis, and transcriptome analysis reveals that they are necessary for the expression of a subset of mitotic mRNAs. Using proteomics, we identify protein clusters associated with the NF45-NF90 complex, including components of Staufen-mediated mRNA decay (SMD). We show that depletion of SMD components increases the binding of mitotic mRNAs to the NF45-NF90 complex and rescues cells from mitotic defects. Together, our results indicate that the NF45-NF90 complex plays essential roles in mitosis by competing with the SMD machinery for a common set of mRNAs.
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Affiliation(s)
- Sami Nourreddine
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Geneviève Lavoie
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Justine Paradis
- Moores Cancer Center, University of California, San Diego, La Jolla, CA 92037, USA
| | | | - Antoine Méant
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Léo Aubert
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Benoit Grondin
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Patrick Gendron
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Benoit Chabot
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Michel Bouvier
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada; Department of Biochemistry and Molecular Medicine, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Sébastien Carreno
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada; Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Philippe P Roux
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montreal, QC H3T 1J4, Canada; Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada.
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5
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STAU2 protein level is controlled by caspases and the CHK1 pathway and regulates cell cycle progression in the non-transformed hTERT-RPE1 cells. BMC Mol Cell Biol 2021; 22:16. [PMID: 33663378 PMCID: PMC7934504 DOI: 10.1186/s12860-021-00352-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 02/22/2021] [Indexed: 11/10/2022] Open
Abstract
Background Staufen2 (STAU2) is an RNA binding protein involved in the posttranscriptional regulation of gene expression. In neurons, STAU2 is required to maintain the balance between differentiation and proliferation of neural stem cells through asymmetric cell division. However, the importance of controlling STAU2 expression for cell cycle progression is not clear in non-neuronal dividing cells. We recently showed that STAU2 transcription is inhibited in response to DNA-damage due to E2F1 displacement from the STAU2 gene promoter. We now study the regulation of STAU2 steady-state levels in unstressed cells and its consequence for cell proliferation. Results CRISPR/Cas9-mediated and RNAi-dependent STAU2 depletion in the non-transformed hTERT-RPE1 cells both facilitate cell proliferation suggesting that STAU2 expression influences pathway(s) linked to cell cycle controls. Such effects are not observed in the CRISPR STAU2-KO cancer HCT116 cells nor in the STAU2-RNAi-depleted HeLa cells. Interestingly, a physiological decrease in the steady-state level of STAU2 is controlled by caspases. This effect of peptidases is counterbalanced by the activity of the CHK1 pathway suggesting that STAU2 partial degradation/stabilization fines tune cell cycle progression in unstressed cells. A large-scale proteomic analysis using STAU2/biotinylase fusion protein identifies known STAU2 interactors involved in RNA translation, localization, splicing, or decay confirming the role of STAU2 in the posttranscriptional regulation of gene expression. In addition, several proteins found in the nucleolus, including proteins of the ribosome biogenesis pathway and of the DNA damage response, are found in close proximity to STAU2. Strikingly, many of these proteins are linked to the kinase CHK1 pathway, reinforcing the link between STAU2 functions and the CHK1 pathway. Indeed, inhibition of the CHK1 pathway for 4 h dissociates STAU2 from proteins involved in translation and RNA metabolism. Conclusions These results indicate that STAU2 is involved in pathway(s) that control(s) cell proliferation, likely via mechanisms of posttranscriptional regulation, ribonucleoprotein complex assembly, genome integrity and/or checkpoint controls. The mechanism by which STAU2 regulates cell growth likely involves caspases and the kinase CHK1 pathway. Supplementary Information The online version contains supplementary material available at 10.1186/s12860-021-00352-y.
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6
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E3 ubiquitin ligase Mindbomb 1 facilitates nuclear delivery of adenovirus genomes. Proc Natl Acad Sci U S A 2020; 118:2015794118. [PMID: 33443154 DOI: 10.1073/pnas.2015794118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The journey from plasma membrane to nuclear pore is a critical step in the lifecycle of DNA viruses, many of which must successfully deposit their genomes into the nucleus for replication. Viral capsids navigate this vast distance through the coordinated hijacking of a number of cellular host factors, many of which remain unknown. We performed a gene-trap screen in haploid cells to identify host factors for adenovirus (AdV), a DNA virus that can cause severe respiratory illness in immune-compromised individuals. This work identified Mindbomb 1 (MIB1), an E3 ubiquitin ligase involved in neurodevelopment, as critical for AdV infectivity. In the absence of MIB1, we observed that viral capsids successfully traffic to the proximity of the nucleus but ultimately fail to deposit their genomes within. The capacity of MIB1 to promote AdV infection was dependent on its ubiquitination activity, suggesting that MIB1 may mediate proteasomal degradation of one or more negative regulators of AdV infection. Employing complementary proteomic approaches to characterize proteins proximal to MIB1 upon AdV infection and differentially ubiquitinated in the presence or absence of MIB1, we observed an intersection between MIB1 and ribonucleoproteins (RNPs) largely unexplored in mammalian cells. This work uncovers yet another way that viruses utilize host cell machinery for their own replication, highlighting a potential target for therapeutic interventions that counter AdV infection.
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Hassine S, Bonnet-Magnaval F, Benoit Bouvrette LP, Doran B, Ghram M, Bouthillette M, Lecuyer E, DesGroseillers L. Staufen1 localizes to the mitotic spindle and controls the localization of RNA populations to the spindle. J Cell Sci 2020; 133:jcs247155. [PMID: 32576666 DOI: 10.1242/jcs.247155] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/07/2020] [Indexed: 12/20/2022] Open
Abstract
Staufen1 (STAU1) is an RNA-binding protein involved in the post-transcriptional regulation of mRNAs. We report that a large fraction of STAU1 localizes to the mitotic spindle in colorectal cancer HCT116 cells and in non-transformed hTERT-RPE1 cells. Spindle-associated STAU1 partly co-localizes with ribosomes and active sites of translation. We mapped the molecular determinant required for STAU1-spindle association within the first 88 N-terminal amino acids, a domain that is not required for RNA binding. Interestingly, transcriptomic analysis of purified mitotic spindles revealed that 1054 mRNAs and the precursor ribosomal RNA (pre-rRNA), as well as the long non-coding RNAs and small nucleolar RNAs involved in ribonucleoprotein assembly and processing, are enriched on spindles compared with cell extracts. STAU1 knockout causes displacement of the pre-rRNA and of 154 mRNAs coding for proteins involved in actin cytoskeleton organization and cell growth, highlighting a role for STAU1 in mRNA trafficking to spindle. These data demonstrate that STAU1 controls the localization of subpopulations of RNAs during mitosis and suggests a novel role of STAU1 in pre-rRNA maintenance during mitosis, ribogenesis and/or nucleoli reassembly.
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Affiliation(s)
- Sami Hassine
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
| | - Florence Bonnet-Magnaval
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
| | - Louis Philip Benoit Bouvrette
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
- Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Bellastrid Doran
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
| | - Mehdi Ghram
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
| | - Mathieu Bouthillette
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
| | - Eric Lecuyer
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
- Institut de Recherches Cliniques de Montréal, 110 Avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Luc DesGroseillers
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Édouard Montpetit, Montréal, QC H3T 1J4, Canada
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8
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Beaujois R, Ottoni E, Zhang X, Gagnon C, Hassine S, Mollet S, Viranaicken W, DesGroseillers L. The M-phase specific hyperphosphorylation of Staufen2 involved the cyclin-dependent kinase CDK1. BMC Cell Biol 2017; 18:25. [PMID: 28705199 PMCID: PMC5513041 DOI: 10.1186/s12860-017-0142-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/10/2017] [Indexed: 01/21/2023] Open
Abstract
Background Staufen2 (STAU2) is an RNA-binding protein involved in the post-transcriptional regulation of gene expression. This protein was shown to be required for organ formation and cell differentiation. Although STAU2 functions have been reported in neuronal cells, its role in dividing cells remains deeply uncharacterized. Especially, its regulation during the cell cycle is completely unknown. Results In this study, we showed that STAU2 isoforms display a mitosis-specific slow migration pattern on SDS-gels in all tested transformed and untransformed cell lines. Deeper analyses in hTert-RPE1 and HeLa cells further indicated that the slow migration pattern of STAU2 isoforms is due to phosphorylation. Time course studies showed that STAU2 phosphorylation occurs before prometaphase and terminates as cells exit mitosis. Interestingly, STAU2 isoforms were phosphorylated on several amino acid residues in the C-terminal half via the cyclin-dependent kinase 1 (Cdk1), an enzyme known to play crucial roles during mitosis. Introduction of phospho-mimetic or phospho-null mutations in STAU2 did not impair its RNA-binding capacity, its stability, its interaction with protein co-factors or its sub-cellular localization, suggesting that STAU2 phosphorylation in mitosis does not regulate these functions. Similarly, STAU2 phosphorylation is not likely to be crucial for cell cycle progression since expression of phosphorylation mutants in hTert-RPE1 cells did not impair cell proliferation. Conclusions Altogether, these results indicate that STAU2 isoforms are phosphorylated during mitosis and that the phosphorylation process involves Cdk1. The meaning of this post-translational modification is still elusive. Electronic supplementary material The online version of this article (doi:10.1186/s12860-017-0142-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rémy Beaujois
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Elizabeth Ottoni
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Xin Zhang
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Christina Gagnon
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Sami Hassine
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Stéphanie Mollet
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Wildriss Viranaicken
- Present address: UMR PIMIT, Processus Infectieux en Milieu Insulaire Tropical, Université de la Réunion, 97490 Sainte Clotilde, La Réunion, France
| | - Luc DesGroseillers
- Département de biochimie et médecine moléculaire, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada.
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