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Domingo-Muelas A, Duart-Abadia P, Morante-Redolat JM, Jordán-Pla A, Belenguer G, Fabra-Beser J, Paniagua-Herranz L, Pérez-Villalba A, Álvarez-Varela A, Barriga FM, Gil-Sanz C, Ortega F, Batlle E, Fariñas I. Post-transcriptional control of a stemness signature by RNA-binding protein MEX3A regulates murine adult neurogenesis. Nat Commun 2023; 14:373. [PMID: 36690670 PMCID: PMC9871011 DOI: 10.1038/s41467-023-36054-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 01/12/2023] [Indexed: 01/25/2023] Open
Abstract
Neural stem cells (NSCs) in the adult murine subependymal zone balance their self-renewal capacity and glial identity with the potential to generate neurons during the lifetime. Adult NSCs exhibit lineage priming via pro-neurogenic fate determinants. However, the protein levels of the neural fate determinants are not sufficient to drive direct differentiation of adult NSCs, which raises the question of how cells along the neurogenic lineage avoid different conflicting fate choices, such as self-renewal and differentiation. Here, we identify RNA-binding protein MEX3A as a post-transcriptional regulator of a set of stemness associated transcripts at critical transitions in the subependymal neurogenic lineage. MEX3A regulates a quiescence-related RNA signature in activated NSCs that is needed for their return to quiescence, playing a role in the long-term maintenance of the NSC pool. Furthermore, it is required for the repression of the same program at the onset of neuronal differentiation. Our data indicate that MEX3A is a pivotal regulator of adult murine neurogenesis acting as a translational remodeller.
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Grants
- EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 European Research Council (H2020 Excellent Science - European Research Council)
- Ministerio de Ciencia e Innovación (MICINN, Spain) - PID2020-119917RB-I00.
- Regional Government of Valencia | Conselleria d'Educació, Investigació, Cultura i Esport (Conselleria d'Educació, Investigació, Cultura i Esport de la Generalitat Valenciana)
- Ministerio de Ciencia e Innovación (MICINN, Spain) - PID2020-117937GB-I00, PID2020-119917RB-I00, PID 2019-109155RB-I00, PID2020-114227RB-I00, RyC-2015-19058, PRE2018-084838. Centro de Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED, Spain) - MICINN- CB06/05/0086.
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Affiliation(s)
- Ana Domingo-Muelas
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Pere Duart-Abadia
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Jose Manuel Morante-Redolat
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Antonio Jordán-Pla
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
| | - Germán Belenguer
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Jaime Fabra-Beser
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
| | - Lucía Paniagua-Herranz
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid (UCM), Madrid, Spain
- Instituto Universitario de Investigación en Neuroquímica (IUIN), Madrid, Spain
- Instituto de Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
| | - Ana Pérez-Villalba
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Adrián Álvarez-Varela
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Barcelona, Spain
| | - Francisco M Barriga
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Barcelona, Spain
| | - Cristina Gil-Sanz
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Felipe Ortega
- Departamento de Bioquímica y Biología Molecular, Universidad Complutense de Madrid (UCM), Madrid, Spain
- Instituto Universitario de Investigación en Neuroquímica (IUIN), Madrid, Spain
- Instituto de Investigación Sanitaria San Carlos (IdISSC), Madrid, Spain
| | - Eduard Batlle
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Barcelona, Spain.
- ICREA, Barcelona, Spain.
| | - Isabel Fariñas
- Departamento de Biología Celular, Biología Funcional y Antropología Física, Universidad de Valencia, Valencia, Spain.
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Universidad de Valencia, Valencia, Spain.
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain.
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Shao X, Le Stunff C, Cheung W, Kwan T, Lathrop M, Pastinen T, Bougnères P. Differentially methylated CpGs in response to growth hormone administration in children with idiopathic short stature. Clin Epigenetics 2022; 14:65. [PMID: 35585611 PMCID: PMC9118695 DOI: 10.1186/s13148-022-01281-z] [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: 01/09/2022] [Accepted: 04/17/2022] [Indexed: 11/17/2022] Open
Abstract
Background Recombinant human growth hormone (rhGH) has shown a great growth-promoting potential in children with idiopathic short stature (ISS). However, the response to rhGH differs across individuals, largely due to genetic and epigenetic heterogeneity. Since epigenetic marks on the methylome can be dynamically influenced by GH, we performed a comprehensive pharmacoepigenomics analysis of DNA methylation changes associated with long-term rhGH administration in children with ISS.
Results We measured DNA methylation profiles before and after GH treatment (with a duration of ~ 18 months in average) on 47 healthy children using customized methylC-seq capture sequencing. Their changes were compared and associated with changes in plasma IGF1 by adjusting sex, age, treatment duration and estimated blood proportions. We observed a considerable inter-individual heterogeneity of DNA methylation changes responding to GH treatment. We identified 267 response-associated differentially methylated cytosines (DMCs) that were enriched in promoter regions, CpG islands and blood cell-type-specific regulatory elements. Furthermore, the genes associated with these DMCs were enriched in the biology process of “cell development,” “neuron differentiation” and “developmental growth,” and in the TGF-beta signaling pathway, PPAR Alpha pathway, endoderm differentiation pathway, adipocytokine signaling pathway as well as PI3K-Akt signaling pathway, and cAMP signaling pathway. Conclusion Our study provides a first insight in DNA methylation changes associated with rhGH administration, which may help understand mechanisms of epigenetic regulation on GH-responsive genes. Supplementary Information The online version contains supplementary material available at 10.1186/s13148-022-01281-z.
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Affiliation(s)
- Xiaojian Shao
- Digital Technologies Research Center, National Research Council Canada, Ottawa, ON, K1A 0R6, Canada.
| | - Catherine Le Stunff
- UMR INSERM 1195 and Université Paris Saclay, Endocrinologie Pédiatrique, Hôpital Bicêtre, 94276, Le Kremlin-Bicêtre Cedex, France
| | - Warren Cheung
- Genomic Medicine Center, Children's Mercy - Kansas City and Children's Mercy Research Institute, Kansas City, MO, 64108, USA
| | - Tony Kwan
- Department of Human Genetics, McGill University and McGill Genome Center, Montreal, QC, H3A 0G1, Canada
| | - Mark Lathrop
- Department of Human Genetics, McGill University and McGill Genome Center, Montreal, QC, H3A 0G1, Canada
| | - Tomi Pastinen
- Genomic Medicine Center, Children's Mercy - Kansas City and Children's Mercy Research Institute, Kansas City, MO, 64108, USA.
| | - Pierre Bougnères
- UMR INSERM 1195 and Université Paris Saclay, Endocrinologie Pédiatrique, Hôpital Bicêtre, 94276, Le Kremlin-Bicêtre Cedex, France.
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Lederer M, Müller S, Glaß M, Bley N, Ihling C, Sinz A, Hüttelmaier S. Oncogenic Potential of the Dual-Function Protein MEX3A. BIOLOGY 2021; 10:415. [PMID: 34067172 PMCID: PMC8151450 DOI: 10.3390/biology10050415] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 04/26/2021] [Accepted: 05/05/2021] [Indexed: 12/23/2022]
Abstract
MEX3A belongs to the MEX3 (Muscle EXcess) protein family consisting of four members (MEX3A-D) in humans. Characteristic for MEX3 proteins is their domain structure with 2 HNRNPK homology (KH) domains mediating RNA binding and a C-terminal really interesting new gene (RING) domain that harbors E3 ligase function. In agreement with their domain composition, MEX3 proteins were reported to modulate both RNA fate and protein ubiquitination. MEX3 paralogs exhibit an oncofetal expression pattern, they are severely downregulated postnatally, and re-expression is observed in various malignancies. Enforced expression of MEX3 proteins in various cancers correlates with poor prognosis, emphasizing their oncogenic potential. The latter is supported by MEX3A's impact on proliferation, self-renewal as well as migration of tumor cells in vitro and tumor growth in xenograft studies.
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Affiliation(s)
- Marcell Lederer
- Charles Tanford Protein Center, Faculty of Medicine, Institute of Molecular Medicine, Section for Molecular Cell Biology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle, Germany; (S.M.).; (M.G.).; (N.B.); (S.H.)
| | - Simon Müller
- Charles Tanford Protein Center, Faculty of Medicine, Institute of Molecular Medicine, Section for Molecular Cell Biology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle, Germany; (S.M.).; (M.G.).; (N.B.); (S.H.)
| | - Markus Glaß
- Charles Tanford Protein Center, Faculty of Medicine, Institute of Molecular Medicine, Section for Molecular Cell Biology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle, Germany; (S.M.).; (M.G.).; (N.B.); (S.H.)
| | - Nadine Bley
- Charles Tanford Protein Center, Faculty of Medicine, Institute of Molecular Medicine, Section for Molecular Cell Biology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle, Germany; (S.M.).; (M.G.).; (N.B.); (S.H.)
| | - Christian Ihling
- Center for Structural Mass Spectrometry, Department of Pharmaceutical Chemistry & Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle (Saale), Germany; (C.I.); (A.S.)
| | - Andrea Sinz
- Center for Structural Mass Spectrometry, Department of Pharmaceutical Chemistry & Bioanalytics, Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle (Saale), Germany; (C.I.); (A.S.)
| | - Stefan Hüttelmaier
- Charles Tanford Protein Center, Faculty of Medicine, Institute of Molecular Medicine, Section for Molecular Cell Biology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle, Germany; (S.M.).; (M.G.).; (N.B.); (S.H.)
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Dodington DW, Yumol JL, Yang J, Pollock-Tahiri E, Sivasubramaniyam T, Sacco SM, Schroer SA, Li YE, Le H, Ward WE, Woo M. JAK2-IGF1 axis in osteoclasts regulates postnatal growth in mice. JCI Insight 2021; 6:137045. [PMID: 33682794 PMCID: PMC8021113 DOI: 10.1172/jci.insight.137045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 01/20/2021] [Indexed: 11/30/2022] Open
Abstract
Osteoclasts are specialized cells of the hematopoietic lineage that are responsible for bone resorption and play a critical role in musculoskeletal disease. JAK2 is a key mediator of cytokine and growth factor signaling; however, its role in osteoclasts in vivo has yet to be investigated. To elucidate the role of JAK2 in osteoclasts, we generated an osteoclast-specific JAK2-KO (Oc-JAK2-KO) mouse using the Cre/Lox-P system. Oc-JAK2-KO mice demonstrated marked postnatal growth restriction; however, this was not associated with significant changes in bone density, microarchitecture, or strength, indicating that the observed phenotype was not due to alterations in canonical osteoclast function. Interestingly, Oc-JAK2-KO mice had reduced osteoclast-specific expression of IGF1, suggesting a role for osteoclast-derived IGF1 in determination of body size. To directly assess the role of osteoclast-derived IGF1, we generated an osteoclast-specific IGF1-KO mouse, which showed a similar growth-restricted phenotype. Lastly, overexpression of circulating IGF1 by human transgene rescued the growth defects in Oc-JAK2-KO mice, in keeping with a causal role of IGF1 in these models. Together, our data show a potentially novel role for Oc-JAK2 and IGF1 in the determination of body size, which is independent of osteoclast resorptive function.
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Affiliation(s)
- David W. Dodington
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | | | - Jiaqi Yang
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Evan Pollock-Tahiri
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Tharini Sivasubramaniyam
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | | | - Stephanie A. Schroer
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Yujin E. Li
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Helen Le
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Wendy E. Ward
- Department of Kinesiology and
- Department of Health Sciences, Brock University, St. Catharines, Ontario, Canada
| | - Minna Woo
- Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Science and Department of Immunology and
- Division of Endocrinology and Metabolism, Department of Medicine, University Health Network/Sinai Health System, University of Toronto, Toronto, Ontario, Canada
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Du Y, Sun D, Li Y. Mex3c mutation affects lactation through impairing milk ejection in female mice. Biosci Rep 2020; 40:BSR20201285. [PMID: 33180120 PMCID: PMC7729293 DOI: 10.1042/bsr20201285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/14/2020] [Accepted: 11/11/2020] [Indexed: 11/24/2022] Open
Abstract
Mouse Mex3c encodes RNA-binding proteins of variant length through alternative splicing. Its mutation results in multiple defects including growth retardation, perturbed energy balance, and defective antiviral innate immunity. Here we report that Mex3c mutation affects mammary gland development and lactation in female mice. Pups of Mex3c mutant dams die of starvation soon after birth. Milk contents are present in the alveoli but deficient in the ducts of the mammary glands in mutant mice. Mutant mice do not show prolactin or oxytocin deficiency. They also develop myoepithelial cells in the mammary glands. Mex3c is expressed in the mammary gland epithelium. Our data suggest that functional defects in mammary gland epithelium or myoepithelial cells could cause lactation defects.
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Affiliation(s)
- Yong Du
- Department of Surgical Research, General Hospital, Ningxia Medical University, Ningxia 750004, China
| | - Dongjun Sun
- Graduate School, Ningxia Medical University, Ningxia 750004, China
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston-Salem, NC 27157, U.S.A
| | - Yan Li
- Department of Obstetrics and Gynecology, General Hospital, Ningxia Medical University, Ningxia 750004, China
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Du Y, Huo Q, Li T, Sun D, Sun T, Lu Z. Construction of a Mex3c Gene-Deficient Mouse Model to Study C-FOS Expression in Hypothalamic Nuclei and Observe Morphological Differences in Embryonic Neural Tube Development. Med Sci Monit 2020; 26:e927334. [PMID: 33191393 PMCID: PMC7678243 DOI: 10.12659/msm.927334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Background This study utilized CRISPR/Cas9 gene editing technology to construct a Mex3c gene-deficient mouse model, and studied C-FOS expression in hypothalamic nuclei. Material/Methods Thirty Mex3c−/+ mice, 30 mice in the normal group, and 30 Mex3c−/+ mice were randomly divided into control, leptin, and ghrelin groups according to different intraperitoneal injections. HE and Nissl staining were performed to observe the morphology of hypothalamic nerve cells. The C-FOS expression in hypothalamic nuclei of each group was analyzed by immunohistochemical techniques. HE staining was used to observe neural tube morphology, and LFB staining was used to observe nerve myelin sheath morphology. TEM was used to observe neuronal ultrastructure and immunohistochemical techniques were utilized to analyze nestin expression. Results C-FOS expression was lower in the normal control group than in the leptin and ghrelin groups. The Mex3c control group and the leptin group had higher C-FOS expression than the ghrelin group. In neural tube studies, no significant differences were found in the neural tube pathological sections of E14.5-day embryos in each group. Nestin results demonstrated lower expression in the normal group and there was little difference between the HD and Mex3c groups. Conclusions Mex3c appears to participate in the regulation of energy metabolism by inducing C-FOS expression in the hypothalamus. The neural tubes of the offspring of Mex3c−/+ mice had defects during development.
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Affiliation(s)
- Yong Du
- Department of Laboratory Surgery, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China (mainland).,Department of Pediatric Surgery, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China (mainland)
| | - Quan Huo
- Department of Pediatric Surgery, College of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China (mainland)
| | - Ting Li
- Department of Pediatric Surgery, College of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China (mainland)
| | - Dongjun Sun
- Department of Pediatric Surgery, College of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China (mainland)
| | - Ting Sun
- Biological Sample Bank, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China (mainland)
| | - Zhiguo Lu
- Department of Pediatric Surgery, College of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China (mainland)
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Whole genome analysis of water buffalo and global cattle breeds highlights convergent signatures of domestication. Nat Commun 2020; 11:4739. [PMID: 32958756 PMCID: PMC7505982 DOI: 10.1038/s41467-020-18550-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 08/26/2020] [Indexed: 12/30/2022] Open
Abstract
More people globally depend on the water buffalo than any other domesticated species, and as the most closely related domesticated species to cattle they can provide important insights into the shared evolutionary basis of domestication. Here, we sequence the genomes of 79 water buffalo across seven breeds and compare patterns of between breed selective sweeps with those seen for 294 cattle genomes representing 13 global breeds. The genomic regions under selection between cattle breeds significantly overlap regions linked to stature in human genetic studies, with a disproportionate number of these loci also shown to be under selection between water buffalo breeds. Investigation of potential functional variants in the water buffalo genome identifies a rare example of convergent domestication down to the same mutation having independently occurred and been selected for across domesticated species. Cross-species comparisons of recent selective sweeps can consequently help identify and refine important loci linked to domestication. The comparative genomics of domesticated lineages can yield insights into the signatures of artificial selection. This study sequences 79 water buffalo genomes from 7 breeds and reveals examples of convergent domestication at the genetic level between water buffalo and cattle.
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Jasinski-Bergner S, Steven A, Seliger B. The Role of the RNA-Binding Protein Family MEX-3 in Tumorigenesis. Int J Mol Sci 2020; 21:ijms21155209. [PMID: 32717840 PMCID: PMC7432607 DOI: 10.3390/ijms21155209] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/16/2020] [Accepted: 07/21/2020] [Indexed: 12/16/2022] Open
Abstract
The muscle excess 3 (MEX-3) protein was first identified in Caenorhabditis elegans (C. elegans), and its respective homologues were also observed in vertebrates, including humans. It is a RNA-binding protein (RBP) with an additional ubiquitin E3 ligase function, which further acts as a post-transcriptional repressor through unknown mechanisms. In humans, MEX-3 proteins post-transcriptionally regulate a number of biological processes, including tumor immunological relevant ones. These have been shown to be involved in various diseases, including tumor diseases of distinct origins. This review provides information on the expression and function of the human MEX-3 family in healthy tissues, as well after malignant transformation. Indeed, the MEX-3 expression was shown to be deregulated in several cancers and to affect tumor biological functions, including apoptosis regulation, antigen processing, and presentation, thereby, contributing to the immune evasion of tumor cells. Furthermore, current research suggests MEX-3 proteins as putative markers for prognosis and as novel targets for the anti-cancer treatment.
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Affiliation(s)
| | | | - Barbara Seliger
- Correspondence: ; Tel.: +49-345-557-1357; Fax: +49-345-557-4055
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Chao H, Deng L, Xu F, Yu Z, Xu X, Huang J, Zeng T. MEX3C regulates lipid metabolism to promote bladder tumorigenesis through JNK pathway. Onco Targets Ther 2019; 12:3285-3294. [PMID: 31118679 PMCID: PMC6503316 DOI: 10.2147/ott.s199667] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 03/02/2019] [Indexed: 01/15/2023] Open
Abstract
Purpose: Bladder cancer (BC) is the most common urinary cancer among men with a high rate of deaths despite the improved medical technology and treatment. Recent evidence demonstrated that Mex-3 RNA-Binding Family Member C (MEX3C) plays various roles in different biological activities, but its molecular mechanisms underlying the pathogenesis of BC remain unclear yet. The aim of this research was to explore the expression patterns of MEX3C and its biological functions in human BC. Materials and methods: The Cancer Genome Atlas (TCGA) and Oncomine databases were jointly used to analyze the expression of MEX3C in BC and its correlation with the clinicopathological features, while real-time PCR and immunohistochemistry analysis were used to verify the predicted results. Wound-healing assay, Matrigel invasion assay, BODIPY staining and Western blot analysis were used in a cell model to assess the effect of MEX3C on the lipid metabolism, invasion and migration of BC and its mechanisms. Results: MEX3C was highly expressed in BC tissues and cells compared with their normal counterparts, and its expression was positively correlated with the clinicopathological features, especially the invasiveness phenotype. Overexpression of MEX3C accumulated lipid droplets and promoted cell adhesion, invasion and migration. We further demonstrated that MEX3C regulated lipid metabolism and promoted tumor development and progression through activation of JNK signaling and upregulating the JNK downstream protein levels of sterol regulatory element-binding proteins-1, fatty acid synthase and acetyl-CoA carboxylase-1. Conclusion: Here we identified MEX3C as a new oncogene to promote bladder tumorigenesis by regulating lipid metabolism through Mitogen-activated protein kinase/c-Jun N-terminal kinase (MAPK/JNK) pathway. These findings suggest a new role of MEX3C in promoting BC tumorigenesis and provide a novel biomarker or molecular target for diagnosis or treating BC.
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Affiliation(s)
- Haichao Chao
- Institute of Clinical Medicine, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, People's Republic of China
| | - Leihong Deng
- Medical Department of Graduate School, Nanchang University, Nanchang, People's Republic of China
| | - Fanghua Xu
- Pathology Department, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, People's Republic of China
| | - Zhaojun Yu
- Medical Department of Graduate School, Nanchang University, Nanchang, People's Republic of China
| | - Xiangda Xu
- Medical Department of Graduate School, Nanchang University, Nanchang, People's Republic of China
| | - Jianbiao Huang
- Medical Department of Graduate School, Nanchang University, Nanchang, People's Republic of China
| | - Tao Zeng
- Department of Urology, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, People's Republic of China
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Wong LL, Saw EL, Lim JY, Zhou Y, Richards AM, Wang P. MicroRNA Let-7d-3p Contributes to Cardiac Protection via Targeting HMGA2. Int J Mol Sci 2019; 20:ijms20071522. [PMID: 30934671 PMCID: PMC6480063 DOI: 10.3390/ijms20071522] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/21/2019] [Accepted: 03/25/2019] [Indexed: 01/01/2023] Open
Abstract
We tested the hypothesis that Let-7d-3p contributes to cardiac cell protection during hypoxic challenge. Myoblast H9c2 cells and primary neonatal rat ventricular cardiomyocytes (NRVM) were transfected with five selected miRNA mimics. Both cell lines were subjected to 0.2% oxygen hypoxia. The protective effects of these miRNAs were determined by assessment of cell metabolic activity by CCK8 assay and measurement of lactate dehydrogenase (LDH) release as a marker of cell injury. Apoptosis and autophagy flux were assessed by Annexin V/7-AAD double staining and the ratio of LC3 II/I with Baf-A1 treatment, an autophagy flux inhibitor, respectively. Luciferase-reporter assay, RT-qPCR and Western blots were performed to identify the changes of relevant gene targets. Among five miRNA mimic transfections, Let-7d-3p increased CCK8 activity, and decreased LDH release in both H9c2 and NRVM during hypoxia. Apoptosis was significantly reduced in H9c2 cells transfected with Let-7d-3p mimic. Autophagy and autophagy flux were not affected. In silico, mRNAs of HMGA2, YY1, KLF9, KLF12, and MEX3C are predicted targets for Let-7d-3p. Luciferase-reporter assay confirmed that Let-7d-3p bound directly to the 3’-UTR region of HMGA2, MEX3C, and YY1, the down-regulations of these mRNAs were verified in both H9c2 and NRVM. The protein expression of HMGA2, but not others, was downregulated in H9c2 and NRVM. It is known that HMGA2 is a strong apoptosis trigger through the blocking of DNA repair. Thus, we speculate that the anti-apoptotic effects of Let-7d-3p mimic during hypoxia challenge are due to direct targeting of HMGA2.
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Affiliation(s)
- Lee Lee Wong
- Cardiovascular Research Institute, National University Heart Centre, Singapore 117599, Singapore.
- Department of Medicine, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
| | - Eng Leng Saw
- Cardiovascular Research Institute, National University Heart Centre, Singapore 117599, Singapore.
- Department of Medicine, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
| | - Jia Yuen Lim
- Cardiovascular Research Institute, National University Heart Centre, Singapore 117599, Singapore.
- Department of Medicine, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
| | - Yue Zhou
- Cardiovascular Research Institute, National University Heart Centre, Singapore 117599, Singapore.
- Department of Medicine, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
| | - Arthur Mark Richards
- Cardiovascular Research Institute, National University Heart Centre, Singapore 117599, Singapore.
- Department of Medicine, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
- Christchurch Heart Institute, Department of Medicine, University of Otago, Christchurch 8014, New Zealand.
| | - Peipei Wang
- Cardiovascular Research Institute, National University Heart Centre, Singapore 117599, Singapore.
- Department of Medicine, Centre for Translational Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore.
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11
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Gonçalves TM, de Almeida Regitano LC, Koltes JE, Cesar ASM, da Silva Andrade SC, Mourão GB, Gasparin G, Moreira GCM, Fritz-Waters E, Reecy JM, Coutinho LL. Gene Co-expression Analysis Indicates Potential Pathways and Regulators of Beef Tenderness in Nellore Cattle. Front Genet 2018; 9:441. [PMID: 30344530 PMCID: PMC6182065 DOI: 10.3389/fgene.2018.00441] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 09/14/2018] [Indexed: 12/13/2022] Open
Abstract
Beef tenderness, a complex trait affected by many factors, is economically important to beef quality, industry, and consumer’s palatability. In this study, RNA-Seq was used in network analysis to better understand the biological processes that lead to differences in beef tenderness. Skeletal muscle transcriptional profiles from 24 Nellore steers, selected by extreme estimated breeding values (EBVs) for shear force after 14 days of aging, were analyzed and 22 differentially expressed transcripts were identified. Among these were genes encoding ribosomal proteins, glutathione transporter ATP-binding cassette, sub-family C (CFTR/MRP), member 4 (ABCC4), and synaptotagmin IV (SYT4). Complementary co-expression analyses using Partial Correlation with Information Theory (PCIT), Phenotypic Impact Factor (PIF) and the Regulatory Impact Factor (RIF) methods identified candidate regulators and related pathways. The PCIT analysis identified ubiquitin specific peptidase 2 (USP2), growth factor receptor-bound protein 10 (GBR10), anoctamin 1 (ANO1), and transmembrane BAX inhibitor motif containing 4 (TMBIM4) as the most differentially hubbed (DH) transcripts. The transcripts that had a significant correlation with USP2, GBR10, ANO1, and TMBIM4 enriched for proteasome KEGG pathway. RIF analysis identified microRNAs as candidate regulators of variation in tenderness, including bta-mir-133a-2 and bta-mir-22. Both microRNAs have target genes present in the calcium signaling pathway and apoptosis. PIF analysis identified myoglobin (MB), enolase 3 (ENO3), and carbonic anhydrase 3 (CA3) as potentially having fundamental roles in tenderness. Pathways identified in our study impacted in beef tenderness included: calcium signaling, apoptosis, and proteolysis. These findings underscore some of the complex molecular mechanisms that control beef tenderness in Nellore cattle.
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Affiliation(s)
| | | | - James E Koltes
- Department of Animal Science, Iowa State University, Ames, IA, United States
| | | | - Sónia Cristina da Silva Andrade
- Department of Animal Science, University of São Paulo, Piracicaba, Brazil.,Department of Genetics and Evolutionary Biology, University of São Paulo, São Paulo, Brazil
| | | | - Gustavo Gasparin
- Department of Animal Science, University of São Paulo, Piracicaba, Brazil
| | | | - Elyn Fritz-Waters
- Department of Animal Science, Iowa State University, Ames, IA, United States
| | - James M Reecy
- Department of Animal Science, Iowa State University, Ames, IA, United States
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12
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Lu P, Li H, Li N, Singh RN, Bishop CE, Chen X, Lu B. MEX3C interacts with adaptor-related protein complex 2 and involves in miR-451a exosomal sorting. PLoS One 2017; 12:e0185992. [PMID: 28982131 PMCID: PMC5628917 DOI: 10.1371/journal.pone.0185992] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 09/23/2017] [Indexed: 12/16/2022] Open
Abstract
Some RNA species, especially microRNAs, are non-randomly sorted into exosomes, but how selectivity of RNA exosomal sorting is achieved is unknown. We found that all three variants of RNA-binding ubiquitin E3 ligase (MEX3C)-MEX3C-1, MEX3C-2, and MEX3C-3 -interact with adaptor-related protein complex 2 (AP-2), a cargo adaptor in clathrin-mediated endocytosis. MEX3C's C-terminal RING finger domain and the hnRNP K homology (KH) domain shared by the three MEX3C variants are both necessary for MEX3C/AP-2 interaction. MEX3C associates with the endolysosomal compartment through an endocytosis-like process. siRNA-mediated inhibition of the MEX3C or AP-2 complex substantially decreased exosomal but not cellular microRNA miR-451a expression. Exosomal sorting is ceramide-dependent but not ESCRT-dependent in microRNA miR-451a. That RNA-binding protein associates with membrane trafficking machinery, and that its involvement in exosomal microRNA expression, suggest the existence of a mechanism for specific recruiting of RNA molecules to endosomes for subsequent exosomal sorting.
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Affiliation(s)
- Pin Lu
- Anhui Normal University, Wuhu, China
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, North Carolina, United States of America
| | - Huanhuan Li
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, North Carolina, United States of America
| | - Ning Li
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, North Carolina, United States of America
| | - Ravi N. Singh
- Department of Cancer Biology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America
| | - Colin E. Bishop
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, North Carolina, United States of America
| | - Xiangxian Chen
- Anhui Normal University, Wuhu, China
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, North Carolina, United States of America
| | - Baisong Lu
- Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston Salem, North Carolina, United States of America
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13
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Yang L, Wang C, Li F, Zhang J, Nayab A, Wu J, Shi Y, Gong Q. The human RNA-binding protein and E3 ligase MEX-3C binds the MEX-3-recognition element (MRE) motif with high affinity. J Biol Chem 2017; 292:16221-16234. [PMID: 28808060 DOI: 10.1074/jbc.m117.797746] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 08/05/2017] [Indexed: 11/06/2022] Open
Abstract
MEX-3 is a K-homology (KH) domain-containing RNA-binding protein first identified as a translational repressor in Caenorhabditis elegans, and its four orthologs (MEX-3A-D) in human and mouse were subsequently found to have E3 ubiquitin ligase activity mediated by a RING domain and critical for RNA degradation. Current evidence implicates human MEX-3C in many essential biological processes and suggests a strong connection with immune diseases and carcinogenesis. The highly conserved dual KH domains in MEX-3 proteins enable RNA binding and are essential for the recognition of the 3'-UTR and post-transcriptional regulation of MEX-3 target transcripts. However, the molecular mechanisms of translational repression and the consensus RNA sequence recognized by the MEX-3C KH domain are unknown. Here, using X-ray crystallography and isothermal titration calorimetry, we investigated the RNA-binding activity and selectivity of human MEX-3C dual KH domains. Our high-resolution crystal structures of individual KH domains complexed with a noncanonical U-rich and a GA-rich RNA sequence revealed that the KH1/2 domains of human MEX-3C bound MRE10, a 10-mer RNA (5'-CAGAGUUUAG-3') consisting of an eight-nucleotide MEX-3-recognition element (MRE) motif, with high affinity. Of note, we also identified a consensus RNA motif recognized by human MEX-3C. The potential RNA-binding sites in the 3'-UTR of the human leukocyte antigen serotype (HLA-A2) mRNA were mapped with this RNA-binding motif and further confirmed by fluorescence polarization. The binding motif identified here will provide valuable information for future investigations of the functional pathways controlled by human MEX-3C and for predicting potential mRNAs regulated by this enzyme.
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Affiliation(s)
- Lingna Yang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
| | - Chongyuan Wang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
| | - Fudong Li
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
| | - Jiahai Zhang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
| | - Anam Nayab
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
| | - Jihui Wu
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
| | - Yunyu Shi
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and.,CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing 100101, China
| | - Qingguo Gong
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027, China and
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14
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Huang Y, Fang C, Shi JW, Wen Y, Liu D. Identification of hMex-3A and its effect on human bladder cancer cell proliferation. Oncotarget 2017; 8:61215-61225. [PMID: 28977858 PMCID: PMC5617418 DOI: 10.18632/oncotarget.18050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/25/2017] [Indexed: 11/25/2022] Open
Abstract
In this study, hMex-3A was selected from TCGA database as a research object to observe the effects of small interfering RNA (siRNA) targeting hMex-3A on the biological activities of human bladder cancer and explore its mechanism for the first time. In this study, there were 2 groups including negative control group and hMex-3A-siRNA-transfected cells group for 5637 and T24 cell lines, respectively. After bladder cancer cells were transfected with the interference RNA sequence, proliferation of transfected cells were assessed by Celigo Cell Counting, and apoptosis were detected by flow cytometry. The knockdown rate of hMex-3A was 74% in 5637 cells and 68% in T24 cells after RNA interference. In addition, Celigo Cell Counting indicated that cell viability was significantly lower in hMex-3A-siRNA-transfected cells group (2196/well) than in negative control group (6777/well) (P < 0.05), but T24 cells did not show statistical significance between hMex-3A-siRNA-transfected cells group (5799/well) and negative control group (7899/well) (P >0.05). Flow cytometer showed that apoptosis was the highest and cells were significantly blocked after cells were transfected in hMex-3A-siRNA-transfected cells group in 5 days later (P < 0.05). Mex-3A protein was detected in bladder carcinoma sections with a mean staining intensity of 7.06±2.60. Mex-3A protein expression was significantly higher in cancerous tissue than in para-cancerous tissue (P <0.05). Our study suggested that siRNA targeting hMex-3A could markedly inhibit cell proliferation and promote apoptosis in 5637 cells. These might have significant implications to bladder carcinogenesis and serve as a potential target for the treatment of bladder cancer.
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Affiliation(s)
- Ying Huang
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Chao Fang
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Jing-Wen Shi
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Yu Wen
- Department of Histoembryology, China Medical University, Shenyang 110000, China
| | - Da Liu
- Department of Orthopedics, Shengjing Hospital of China Medical University, Shenyang 110004, China
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15
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Ramayo-Caldas Y, Renand G, Ballester M, Saintilan R, Rocha D. Multi-breed and multi-trait co-association analysis of meat tenderness and other meat quality traits in three French beef cattle breeds. Genet Sel Evol 2016; 48:37. [PMID: 27107817 PMCID: PMC4842279 DOI: 10.1186/s12711-016-0216-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 04/13/2016] [Indexed: 01/19/2023] Open
Abstract
Background Studies to identify markers associated with beef tenderness have focused on Warner–Bratzler shear force (WBSF) but the interplay between the genes associated with WBSF has not been explored. We used the association weight matrix (AWM), a systems biology approach, to identify a set of interacting genes that are co-associated with tenderness and other meat quality traits, and shared across the Charolaise, Limousine and Blonde d’Aquitaine beef cattle breeds. Results Genome-wide association studies were performed using ~500K single nucleotide polymorphisms (SNPs) and 17 phenotypes measured on more than 1000 animals for each breed. First, this multi-trait approach was applied separately for each breed across 17 phenotypes and second, between- and across-breed comparisons at the AWM and functional levels were performed. Genetic heterogeneity was observed, and most of the variants that were associated with WBSF segregated within rather than across breeds. We identified 206 common candidate genes associated with WBSF across the three breeds. SNPs in these common genes explained between 28 and 30 % of the phenotypic variance for WBSF. A reduced number of common SNPs mapping to the 206 common genes were identified, suggesting that different mutations may target the same genes in a breed-specific manner. Therefore, it is likely that, depending on allele frequencies and linkage disequilibrium patterns, a SNP that is identified for one breed may not be informative for another unrelated breed. Well-known candidate genes affecting beef tenderness were identified. In addition, some of the 206 common genes are located within previously reported quantitative trait loci for WBSF in several cattle breeds. Moreover, the multi-breed co-association analysis detected new candidate genes, regulators and metabolic pathways that are likely involved in the determination of meat tenderness and other meat quality traits in beef cattle. Conclusions Our results suggest that systems biology approaches that explore associations of correlated traits increase statistical power to identify candidate genes beyond the one-dimensional approach. Further studies on the 206 common genes, their pathways, regulators and interactions will expand our knowledge on the molecular basis of meat tenderness and could lead to the discovery of functional mutations useful for genomic selection in a multi-breed beef cattle context. Electronic supplementary material The online version of this article (doi:10.1186/s12711-016-0216-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Gilles Renand
- GABI, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Maria Ballester
- GABI, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.,Genètica i Millora Animal, IRTA, 08140, Torre Marimon, Caldes de Montbui, Spain
| | | | - Dominique Rocha
- GABI, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
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16
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Li X, Li Y, Liu C, Jin M, Lu B. Oocyte-Specific Expression of Mouse MEX3C652AA in the Ovary and Its Potential Role in Regulating Maternal Fos mRNA. Biol Reprod 2016; 94:115. [PMID: 27053362 DOI: 10.1095/biolreprod.115.136630] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 03/29/2016] [Indexed: 12/31/2022] Open
Abstract
Currently, the human MEX3C gene is known to encode an RNA-binding protein of 659 amino acid residues. Here we show that the MEX3C gene has alternative splicing forms giving rise to multiple MEX3C variants, and some cells express MEX3C transcripts coding for short MEX3C isoforms but not transcripts for MEX3C(659AA) MEX3C(659AA) functions as an adaptor protein for Exportin 1 (XPO1)-mediated nuclear export since it increases the cytoplasmic distribution of poly(A)(+) RNA and since addition of the nuclear export signal (NES) sequence to a short MEX3C isoform MEX3C(464AA) confers similar cytoplasmic poly(A)(+) RNA accumulation activity as MEX3C(659AA) FOS mRNA is a potential MEX3C target mRNA. One mechanism by which MEX3C(659AA) could regulate FOS mRNA is by promoting its nuclear export. Overexpressing MEX3C(659AA) significantly increased FOS mRNA expression, whereas mutating the NES of MEX3C(659AA) and treating cells with leptomycin B to inhibit XPO1-mediated nuclear export attenuated FOS upregulation. FOS mRNA is unstable in somatic cells but less so in oocytes; how it is stabilized in the oocytes is unknown. Transcripts for the mouse counterpart of human MEX3C(659AA) (MEX3C(652AA)) are specifically expressed in developing oocytes in the ovary, although total Mex3c transcripts are expressed in both granulosa cells and oocytes. The specific expression of this long MEX3C isoform in oocytes and its ability to enhance FOS mRNA nuclear export and stability all suggest that MEX3C(659AA) is an RNA-binding protein that preserves maternal FOS mRNA in oocytes.
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Affiliation(s)
- Xue Li
- Department of Pathology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, People's Republic of China Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina
| | - Yan Li
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina General Hospital, Ningxia Medical University, Ningxia, People's Republic of China
| | - Chunlian Liu
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina General Hospital, Ningxia Medical University, Ningxia, People's Republic of China
| | - Mulan Jin
- Department of Pathology, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Baisong Lu
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina
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17
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Huang NN, Hunter CP. The RNA binding protein MEX-3 retains asymmetric activity in the early Caenorhabditis elegans embryo in the absence of asymmetric protein localization. Gene 2014; 554:160-73. [PMID: 25445286 DOI: 10.1016/j.gene.2014.10.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/23/2014] [Accepted: 10/25/2014] [Indexed: 10/24/2022]
Abstract
The RNA binding protein MEX-3 is required to restrict translation of pal-1, the Caenorhabditis elegans caudal homolog, to the posterior of the early embryo. MEX-3 is present uniformly throughout the newly fertilized embryo, but becomes depleted in the posterior by the 4-cell stage. This MEX-3 patterning requires the CCCH zinc-finger protein MEX-5, the RNA Recognition Motif protein SPN-4, and the kinase PAR-4. Genetic and biochemical evidence suggests that MEX-5 binds to MEX-3 in the anterior of the embryo, protecting MEX-3 from degradation and allowing it to bind the pal-1 3'UTR and repress translation. MEX-3 that is not bound to MEX-5 becomes inactivated by par-4, then targeted for spn-4 dependent degradation. After the 4-cell stage, residual MEX-3 is degraded in somatic cells, and only persists in the germline precursors. To better understand regulation of mex-3, GFP was fused to MEX-3 or regions of MEX-3 and expressed in developing oocytes. GFP::MEX-3 expressed in this manner can replace endogenous MEX-3, but surprisingly is not asymmetrically localized at the 4-cell stage. These results indicate that GFP::MEX-3 retains asymmetric activity even in the absence of asymmetric protein localization. Neither the mex-3 3'UTR nor protein degradation at the 4-cell stage is strictly required. A region of MEX-3 containing a glutamine-rich region and potential ubiquitination and phosphorylation sites is sufficient for soma-germline asymmetry. Results from mex-5/6 and spn-4(RNAi) suggest two pathways for MEX-3 degradation, an early spn-4 dependent pathway and a later spn-4 independent pathway. These results indicate that mex-3 activity is regulated at multiple levels, leading to rapid and robust regulation in the quickly developing early embryo.
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Affiliation(s)
- Nancy N Huang
- Molecular Biology Department, Colorado College, Colorado Springs, CO 80903, USA.
| | - Craig P Hunter
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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18
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Bharadwaj MS, Zhou Y, Molina AJ, Criswell T, Lu B. Examination of bioenergetic function in the inner mitochondrial membrane peptidase 2-like (Immp2l) mutant mice. Redox Biol 2014; 2:1008-15. [PMID: 25460737 PMCID: PMC4215389 DOI: 10.1016/j.redox.2014.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 08/14/2014] [Accepted: 08/25/2014] [Indexed: 11/17/2022] Open
Abstract
Inner mitochondrial membrane peptidase 2-like (IMMP2L) protein is a mitochondrial inner membrane peptidase that cleaves the signal peptide sequences of cytochrome c1 (CYC1) and mitochondrial glycerol phosphate dehydrogenase (GPD2). Immp2l mutant mice show infertility and early signs of aging. It is unclear whether mitochondrial respiratory deficiency underlies this phenotype. Here we show that the intermediate forms of GPD2 and CYC1 have normal expression levels and enzymatic function in Immp2l mutants. Mitochondrial respiration is not diminished in isolated mitochondria and cells from mutant mice. Our data suggest that respiratory deficiency is not the cause of the observed Immp2l mutant phenotypes. Expression of IMMP2L substrates CYC1 and GPD2 is not affected in Immp2l mutant mice. Mitochondria of mutant mice have normal complex III and GPD2 activities. Mitochondrial respiration of mutant mice is not diminished.
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Affiliation(s)
- Manish S Bharadwaj
- Section on Gerontology and Geriatric Medicine, Wake Forest University Health Sciences, Department of Internal Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Yu Zhou
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Anthony J Molina
- Section on Gerontology and Geriatric Medicine, Wake Forest University Health Sciences, Department of Internal Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Tracy Criswell
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Baisong Lu
- Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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19
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Abstract
MEX3C is an RNA-binding protein with unknown physiological function. We have recently reported that a Mex3c mutation in mice causes growth retardation and reduced adiposity, but how adiposity is reduced remains unclear. Herein, we show that homozygous Mex3c gene trap mice have increased physical activity. The Mex3c mutation consistently conferred full protection from diet-induced obesity, hyperglycemia, insulin resistance, hyperlipidemia, and hepatic steatosis. In ob/ob mice with leptin deficiency, the Mex3c mutation also increased physical activity and improved glucose and lipid profiles. Expressing cre in the neurons of Mex3c gene trap mice, an attempt to partially restoring neuronal Mex3c expression, significantly increased white adipose tissue deposition, but had no effects on body length. Our data suggest that one way in which Mex3c regulates adiposity is through controlling physical activity, and that neuronal Mex3c expression could play an important role in this process.
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Affiliation(s)
- Changjie Han
- Institute for Regenerative MedicineWake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USADepartment of Human Anatomy and EmbryologyThe Second Military Medical University, Shanghai 200433, ChinaInstitute for Regenerative MedicineWake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USADepartment of Human Anatomy and EmbryologyThe Second Military Medical University, Shanghai 200433, China
| | - Yan Jiao
- Institute for Regenerative MedicineWake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USADepartment of Human Anatomy and EmbryologyThe Second Military Medical University, Shanghai 200433, China
| | - Qingguo Zhao
- Institute for Regenerative MedicineWake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USADepartment of Human Anatomy and EmbryologyThe Second Military Medical University, Shanghai 200433, China
| | - Baisong Lu
- Institute for Regenerative MedicineWake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USADepartment of Human Anatomy and EmbryologyThe Second Military Medical University, Shanghai 200433, China
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20
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Le Borgne M, Chartier N, Buchet-Poyau K, Destaing O, Faurobert E, Thibert C, Rouault JP, Courchet J, Nègre D, Bouvard D, Albiges-Rizo C, Rousseaux S, Khochbin S, Segretain D, Crépieux P, Guillou F, Durand P, Perrard MH, Billaud M. The RNA-binding protein Mex3b regulates the spatial organization of the Rap1 pathway. Development 2014; 141:2096-107. [DOI: 10.1242/dev.108514] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The four related mammalian MEX-3 RNA-binding proteins are evolutionarily conserved molecules for which the in vivo functions have not yet been fully characterized. Here, we report that male mice deficient for the gene encoding Mex3b are subfertile. Seminiferous tubules of Mex3b-deficient mice are obstructed as a consequence of the disrupted phagocytic capacity of somatic Sertoli cells. In addition, both the formation and the integrity of the blood-testis barrier are compromised owing to mislocalization of N-cadherin and connexin 43 at the surface of Sertoli cells. We further establish that Mex3b acts to regulate the cortical level of activated Rap1, a small G protein controlling phagocytosis and cell-cell interaction, through the activation and transport of Rap1GAP. The active form of Rap1 (Rap1-GTP) is abnormally increased at the membrane cortex and chemically restoring Rap1-GTP to physiological levels rescues the phagocytic and adhesion abilities of Sertoli cells. Overall, these findings implicate Mex3b in the spatial organization of the Rap1 pathway that orchestrates Sertoli cell functions.
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Affiliation(s)
- Maïlys Le Borgne
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Nicolas Chartier
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Karine Buchet-Poyau
- Hospices Civils de Lyon, Pôle Information Médicale Evaluation Recherche, Lyon F-69003, France
| | - Olivier Destaing
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Eva Faurobert
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Chantal Thibert
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Jean-Pierre Rouault
- Institut de Génomique Fonctionnelle de Lyon, UMR5242 CNRS/INRA/UCBL/ENS, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, Lyon 69364, Cedex 07, France
| | - Julien Courchet
- Columbia University Department of Neurosciences, New York, NY 10032, USA
| | - Didier Nègre
- Université de Lyon, Inserm, EVIR, U758, Human Virology Department, Ecole Normale Supérieure de Lyon, Université Lyon 1, Lyon F-69007, France
| | - Daniel Bouvard
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Corinne Albiges-Rizo
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Sophie Rousseaux
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Saadi Khochbin
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
| | - Dominique Segretain
- UMR S775, University Paris Descartes, 45 rue des Saints Pères, Paris 75006, France
- University of Versailles, Saint Quentin 78035, France
| | - Pascale Crépieux
- Physiologie de la Reproduction et des Comportements, UMR 7247 INRA-CNRS-Université de Tours, Nouzilly 37380, France
| | - Florian Guillou
- Physiologie de la Reproduction et des Comportements, UMR 7247 INRA-CNRS-Université de Tours, Nouzilly 37380, France
| | - Philippe Durand
- Institut de Génomique Fonctionnelle de Lyon, UMR5242 CNRS/INRA/UCBL/ENS, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, Lyon 69364, Cedex 07, France
| | - Marie-Hélène Perrard
- Institut de Génomique Fonctionnelle de Lyon, UMR5242 CNRS/INRA/UCBL/ENS, Ecole Normale Supérieure de Lyon, 46, allée d'Italie, Lyon 69364, Cedex 07, France
| | - Marc Billaud
- INSERM, U823; Université Joseph Fourier-Grenoble 1; Institut Albert Bonniot, Grenoble F-38700, France
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Ouyang M, Li Y, Ye S, Ma J, Lu L, Lv W, Chang G, Li X, Li Q, Wang S, Wang W. MicroRNA profiling implies new markers of chemoresistance of triple-negative breast cancer. PLoS One 2014; 9:e96228. [PMID: 24788655 PMCID: PMC4008525 DOI: 10.1371/journal.pone.0096228] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/04/2014] [Indexed: 02/06/2023] Open
Abstract
Objective Triple-negative breast cancer (TNBC) patients with truly chemosensitive disease still represent a minority among all TNBC patients. The aim of the present study is to identify microRNAs (miRNAs) that correlate with TNBC chemoresistance. Methods In this study, we conducted miRNAs profile comparison between triple-negative breast cancer (TNBCs) and normal breast tissues by microRNA array. Quantitative real-time PCR (qRT-PCR) was utilized to confirm the specific deregulated miRNAs change trend. We used starBase 2.1 and GOrilla to predict the potential targets of the specific miRNAs. Cells viability and apoptosis assays were employed to determine the effect of alteration of the specific miRNAs in TNBC cells on the chemosensitivity. Results We identified 11 specific deregulated miRNAs, including 5 up-regulated miRNAs (miR-155-5p, miR-21-3p, miR-181a-5p, miR-181b-5p, and miR-183-5p) and 6 down-regulated miRNAs (miR-10b-5p, miR-451a, miR-125b-5p, miR-31-5p, miR-195-5p and miR-130a-3p). Thereafter, this result was confirmed by qRT-PCR. We predicted the potential targets of the candidate miRNAs and found that they are involved in cancer-associated pathways. For the first time, we found that miR-130a-3p and miR-451a were down-regulated in TNBC. 9 of the 11 specific deregulated miRNAs were found to be associated with chemoresistance. In vitro assays, we found that up-regulation of either miR-130a-3p or miR-451a in MDA-MB-231 cells significantly changed the cells sensitivity to doxorubicin. The results suggest that TNBC chemotherapy might be affected by a cluster of miRNAs. Conclusion The abnormal expression miRNAs in TNBC are mainly chemoresistance related. This might be part of reason that TNBC likely to evade from chemotherapy resulting in early relapse and high risk of death. To alter their expression status might be a potential therapeutic strategy to improve the outcome of chemotherapy for TNBC patients.
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Affiliation(s)
- Mao Ouyang
- Laboratory of Department of Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
- Center for Cellular and Structural Biology, Guangzhou, Guangdong, People's Republic of China
- Department of Clinical Laboratory, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Yongxin Li
- Laboratory of Department of Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Sheng Ye
- Department of Medical Oncology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Jieyi Ma
- Laboratory of Department of Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Liming Lu
- Department of Medical Statistics and Epidemiology, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Weiming Lv
- Department of Vascular, Thyroid and Breast Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Guangqi Chang
- Department of Vascular, Thyroid and Breast Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Xiaoxi Li
- Department of Vascular, Thyroid and Breast Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
| | - Qing Li
- Center for Cellular and Structural Biology, Guangzhou, Guangdong, People's Republic of China
- * E-mail: (WW); (SW); (QL)
| | - Shenming Wang
- Department of Vascular, Thyroid and Breast Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
- * E-mail: (WW); (SW); (QL)
| | - Wenjian Wang
- Laboratory of Department of Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China
- * E-mail: (WW); (SW); (QL)
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Pivotal role of RNA-binding E3 ubiquitin ligase MEX3C in RIG-I-mediated antiviral innate immunity. Proc Natl Acad Sci U S A 2014; 111:5646-51. [PMID: 24706898 DOI: 10.1073/pnas.1401674111] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The RIG-I-like receptors, retinoic acid inducible gene-1 (RIG-I), melanoma differentiation-associated protein 5, and laboratory of genetics and physiology-2, are cytoplasmic sensors for RNA viruses that mediate the antiviral innate immune responses. We demonstrate that really interesting new gene-finger domain- and K homology domain-containing MEX3C regulates RIG-I function. MEX3C colocalizes with RIG-I in the stress granules of virally infected cells, and its overexpression causes the lysine-63-linked ubiquitination of RIG-I and activates IFN-β promoter. Embryonic fibroblast cells, macrophages, and conventional dendritic cells derived from Mex3c-deficient mice showed defective production of type I IFN after infection with RNA viruses that are recognized by RIG-I. These results demonstrate that MEX3C is an E3 ubiquitin ligase that modifies RIG-I in stress granules and plays a critical role in eliciting antiviral immune responses.
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The role of nitric oxide signaling in food intake; insights from the inner mitochondrial membrane peptidase 2 mutant mice. Redox Biol 2013; 1:498-507. [PMID: 24251118 PMCID: PMC3830068 DOI: 10.1016/j.redox.2013.10.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 10/14/2013] [Accepted: 10/16/2013] [Indexed: 12/27/2022] Open
Abstract
Reactive oxygen species have been implicated in feeding control through involvement in brain lipid sensing, and regulating NPY/AgRP and pro-opiomelanocortin (POMC) neurons, although the underlying mechanisms are unclear. Nitric oxide is a signaling molecule in neurons and it stimulates feeding in many species. Whether reactive oxygen species affect feeding through interaction with nitric oxide is unclear. We previously reported that Immp2l mutation in mice causes excessive mitochondrial superoxide generation, which causes infertility and early signs of aging. In our present study, reduced food intake in mutant mice resulted in significantly reduced body weight and fat composition while energy expenditure remained unchanged. Lysate from mutant brain showed a significant decrease in cGMP levels, suggesting insufficient nitric oxide signaling. Thus, our data suggests that reactive oxygen species may regulate food intake through modulating the bioavailability of nitric oxide. Mature adult Immp2l mutant mice have reduced body weight and fat composition. Reduced body weight and fat composition is caused by reduced food intake. Energy expenditure is not affected in mutant mice. Brain cGMP level is lower in mutant mice.
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Key Words
- ADSC, adipose-derived stromal cells
- AMPK, AMP-activated protein kinase.
- AgRP, agouti related protein
- CART, cocaine- and amphetamine-regulated transcript
- CYC1, cytochrome c1
- Energy expenditure
- Food intake
- GPD2, mitochondrial glycerol phosphate dehydrogenase
- Immp2l
- Immp2l, IMP2 inner mitochondrial membrane peptidase-like
- Mutant mice
- NO, nitric oxide
- NOS, nitric oxide synthase
- NPY, neuropeptide Y
- Nitric oxide
- POMC, pro-opiomelanocortin
- ROS, reactive oxygen species
- Superoxide
- UCP2, uncoupling protein 2
- cGMP, cyclic guanosine monophosphate
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Pereira B, Sousa S, Barros R, Carreto L, Oliveira P, Oliveira C, Chartier NT, Plateroti M, Rouault JP, Freund JN, Billaud M, Almeida R. CDX2 regulation by the RNA-binding protein MEX3A: impact on intestinal differentiation and stemness. Nucleic Acids Res 2013; 41:3986-99. [PMID: 23408853 PMCID: PMC3627580 DOI: 10.1093/nar/gkt087] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The homeobox transcription factor CDX2 plays a crucial role in intestinal cell fate specification, both during normal development and in tumorigenic processes involving intestinal reprogramming. The CDX2 regulatory network is intricate, but it has not yet been fully uncovered. Through genome-wide screening of a 3D culture system, the RNA-binding protein MEX3A was identified as putatively involved in CDX2 regulation; therefore, its biological relevance was addressed by setting up cell-based assays together with expression studies in murine intestine. We demonstrate here that MEX3A has a repressive function by controlling CDX2 levels in gastric and colorectal cellular models. This is dependent on the interaction with a specific binding determinant present in CDX2 mRNA 3'untranslated region. We have further determined that MEX3A impairs intestinal differentiation and cellular polarization, affects cell cycle progression and promotes increased expression of intestinal stem cell markers, namely LGR5, BMI1 and MSI1. Finally, we show that MEX3A is expressed in mouse intestine, supporting an in vivo context for interaction with CDX2 and modulation of stem cell properties. Therefore, we describe a novel CDX2 post-transcriptional regulatory mechanism, through the RNA-binding protein MEX3A, with a major impact in intestinal differentiation, polarity and stemness, likely contributing to intestinal homeostasis and carcinogenesis.
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Affiliation(s)
- Bruno Pereira
- IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, 4200-465 Porto, Portugal
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Smith SS, Kessler CB, Shenoy V, Rosen CJ, Delany AM. IGF-I 3' untranslated region: strain-specific polymorphisms and motifs regulating IGF-I in osteoblasts. Endocrinology 2013; 154:253-62. [PMID: 23183171 PMCID: PMC3529377 DOI: 10.1210/en.2012-1476] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 11/06/2012] [Indexed: 12/12/2022]
Abstract
Reduced IGF-I is associated with low bone mass in humans and mice. C3H/He/J (C3H) mice have higher skeletal IGF-I and greater bone mass than C57BL/6J (B6). We hypothesized that strain-related genotypic differences in Igf1 affected skeletal function. The Igf1 coding region is nonpolymorphic, but its 3' untranslated region (UTR) is polymorphic between C3H and B6. Luciferase-Igf1 3' UTR reporter constructs showed that these polymorphic regions did not affect UTR function. IGF-I splice variants give rise to a common mature IGF-I peptide, but different E peptides. We identified two splice products, exon 4+6 (Ea) and exon 4+5+6 (Eb, mechano-growth factor) and found that their abundance was unchanged during osteoblastic differentiation. The Igf1 3' UTR encoded by exon 6 contains alternative polyadenylation sites. Proximal site use produces a short 3' UTR of approximately 195 bases, whereas distal site usage results in an approximately 6300-base UTR. Although Igf1 mRNA levels did not change during osteoblastic differentiation, distal polyadenylation site usage was increased in B6 cells but not in C3H. The resulting long Igf1 RNA isoform is less stable and has decreased translation efficiency, which may be one mechanism contributing to decreased IGF-I in B6 vs. C3H mice. Although the long UTR contains a conserved [GU](18) repeat, which is a positive regulator of UTR activity, it is also targeted by negative regulators, miR-29 and miR-365. These microRNAs are increased in B6 and C3H cells during osteoblastic differentiation. Differential expression of the long Igf1 3' UTR isoform may be a possible mechanism for enhanced IGF-I regulation in B6 vs. C3H mice.
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Affiliation(s)
- Spenser S Smith
- Center for Molecular Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
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Abstract
The function of MEX3C, the mammalian homolog of Caenorhabditis elegans RNA-binding protein muscle excess 3 (MEX-3), was unknown until our recent report that MEX3C is necessary for normal postnatal growth and enhances the expression of local bone Igf1 expression. Here we report the pivotal role of Mex3c in energy balance regulation. Mex3c mutation caused leanness in both heterozygous and homozygous transgenic mice, as well as a more beneficial blood glucose and lipid profile in homozygous transgenic mice, in both sexes. Although transgenic mice showed normal food intake and fecal lipid excretion, they had increased energy expenditure independent of physical activity. Mutant mice had normal body temperature, Ucp1 expression in brown adipose tissue, and muscle and liver fatty acid oxidation. Mex3c is expressed in neurons and is detectable in the arcuate nucleus, the ventromedial nucleus, and the dorsomedial nucleus of the hypothalamus. Mex3c was not detected in NPY or POMC neurons but was detected in leptin-responsive neurons in the ventromedial nucleus. Mex3c and Leptin double mutant mice were growth retarded and obese and had blood profiles similar to those of ob/ob mice but showed none of the steatosis observed in ob/ob mice. Our data show that Mex3c is involved in energy balance regulation.
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