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Bjorkman KK, Guess MG, Harrison BC, Polmear MM, Peter AK, Leinwand LA. miR-206 enforces a slow muscle phenotype. J Cell Sci 2020; 133:jcs243162. [PMID: 32620696 PMCID: PMC7438006 DOI: 10.1242/jcs.243162] [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: 12/31/2019] [Accepted: 06/25/2020] [Indexed: 12/21/2022] Open
Abstract
Striated muscle is a highly specialized collection of tissues with contractile properties that vary according to functional needs. Although muscle fiber types are established postnatally, lifelong plasticity facilitates stimulus-dependent adaptation. Functional adaptation requires molecular adaptation, which is partially provided by miRNA-mediated post-transcriptional regulation. miR-206 is a muscle-specific miRNA enriched in slow muscles. We investigated whether miR-206 drives the slow muscle phenotype or is merely an outcome. We found that miR-206 expression increases in both physiological (including female sex and endurance exercise) and pathological conditions (muscular dystrophy and adrenergic agonism) that promote a slow phenotype. Consistent with that observation, the slow soleus muscle of male miR-206-knockout mice displays a faster phenotype than wild-type mice. Moreover, left ventricles of male miR-206 knockout mice have a faster myosin profile, accompanied by dilation and systolic dysfunction. Thus, miR-206 appears to be necessary to enforce a slow skeletal and cardiac muscle phenotype and to play a key role in muscle sexual dimorphisms.
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Affiliation(s)
- Kristen K Bjorkman
- Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave., UCB596, Boulder, CO 80303, USA
| | - Martin G Guess
- Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave., UCB596, Boulder, CO 80303, USA
| | - Brooke C Harrison
- Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave., UCB596, Boulder, CO 80303, USA
| | - Michael M Polmear
- Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave., UCB596, Boulder, CO 80303, USA
| | - Angela K Peter
- Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave., UCB596, Boulder, CO 80303, USA
| | - Leslie A Leinwand
- Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, University of Colorado Boulder, 3415 Colorado Ave., UCB596, Boulder, CO 80303, USA
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Law WD, Fogarty EA, Vester A, Antonellis A. A genome-wide assessment of conserved SNP alleles reveals a panel of regulatory SNPs relevant to the peripheral nerve. BMC Genomics 2018; 19:311. [PMID: 29716548 PMCID: PMC5930951 DOI: 10.1186/s12864-018-4692-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 04/17/2018] [Indexed: 12/29/2022] Open
Abstract
Background Identifying functional non-coding variation is critical for defining the genetic contributions to human disease. While single-nucleotide polymorphisms (SNPs) within cis-acting transcriptional regulatory elements have been implicated in disease pathogenesis, not all cell types have been assessed and functional validations have been limited. In particular, the cells of the peripheral nervous system have been excluded from genome-wide efforts to link non-coding SNPs to altered gene function. Addressing this gap is essential for defining the genetic architecture of diseases that affect the peripheral nerve. We developed a computational pipeline to identify SNPs that affect regulatory function (rSNPs) and evaluated our predictions on a set of 144 regions in Schwann cells, motor neurons, and muscle cells. Results We identified 28 regions that display regulatory activity in at least one cell type and 13 SNPs that affect regulatory function. We then tailored our pipeline to one peripheral nerve cell type by incorporating SOX10 ChIP-Seq data; SOX10 is essential for Schwann cells. We prioritized 22 putative SOX10 response elements harboring a SNP and rapidly validated two rSNPs. We then selected one of these elements for further characterization to assess the biological relevance of our approach. Deletion of the element from the genome of cultured Schwann cells—followed by differential gene expression studies—revealed Tubb2b as a candidate target gene. Studying the enhancer in developing mouse embryos revealed activity in SOX10-positive cells including the dorsal root ganglia and melanoblasts. Conclusions Our efforts provide insight into the utility of employing strict conservation for rSNP discovery. This strategy, combined with functional analyses, can yield candidate target genes. In support of this, our efforts suggest that investigating the role of Tubb2b in SOX10-positive cells may reveal novel biology within these cell populations. Electronic supplementary material The online version of this article (10.1186/s12864-018-4692-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- William D Law
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Elizabeth A Fogarty
- Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Aimée Vester
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Anthony Antonellis
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA. .,Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA. .,Department of Neurology, University of Michigan Medical School, 3710A Medical Sciences II, 1241 E. Catherine St. SPC 5618, Ann Arbor, MI, 48109, USA.
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Huang WY, Xie W, Guo X, Li F, Jose PA, Chen SY. Smad2 and PEA3 cooperatively regulate transcription of response gene to complement 32 in TGF-β-induced smooth muscle cell differentiation of neural crest cells. Am J Physiol Cell Physiol 2011; 301:C499-506. [PMID: 21613609 PMCID: PMC3154553 DOI: 10.1152/ajpcell.00480.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 05/20/2011] [Indexed: 11/22/2022]
Abstract
Response gene to complement 32 (RGC-32) is activated by transforming growth factor- β (TGF-β) and plays an important role in smooth muscle cell (SMC) differentiation from neural crest Monc-1 cells. The molecular mechanism governing TGF-β activation of RGC-32, however, remains to be determined. The present studies indicate that TGF-β regulates RGC-32 gene transcription. Sequence analysis revealed a Smad binding element (SBE) located in the region from -1344 to -1337 bp upstream of the transcription start site of RGC-32 gene. A polyomavirus enhancer activator (PEA3) binding site is adjacent to the SBE. Mutation at either SBE or PEA3 site significantly inhibited RGC-32 promoter activity. Mutations at both sites completely abolished TGF-β-induced promoter activity. Biochemically, TGF-β stimulated recruitment of Smad2, Smad4, and PEA3 to the RGC-32 promoter, as revealed by gel shift and chromatin immunoprecipitation analyses. Functionally, Smad2, but not Smad3, activated RGC-32 promoter. PEA3 appeared to enhance Smad2 activity. In agreement with their function, Smad2, but not Smad3, physically interacted with PEA3. In TGF-β-induced SMC differentiation of Monc-1 cells, knockdown of Smad2 by short hairpin RNA resulted in downregulation of RGC-32 and SMC marker genes. The downregulation of SMC markers, however, was rescued by exogenously introduced RGC-32. These results demonstrate that Smad2 regulation of RGC-32 transcription is essential for SMC differentiation from neural crest cells.
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Affiliation(s)
- Wen-Yan Huang
- Department of Physiology and Pharmacology, The University of Georgia, Athens, GA 30602, USA
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Li HM, Sun L, Mittapalli O, Muir WM, Xie J, Wu J, Schemerhorn BJ, Jannasch A, Chen JY, Zhang F, Adamec J, Murdock LL, Pittendrigh BR. Bowman-Birk inhibitor affects pathways associated with energy metabolism in Drosophila melanogaster. INSECT MOLECULAR BIOLOGY 2010; 19:303-313. [PMID: 20113373 DOI: 10.1111/j.1365-2583.2009.00984.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Bowman-Birk inhibitor (BBI) is toxic when fed to certain insects, including the fruit fly, Drosophila melanogaster. Dietary BBI has been demonstrated to slow growth and increase insect mortality by inhibiting the digestive enzymes trypsin and chymotrypsin, resulting in a reduced supply of amino acids. In mammals, BBI influences cellular energy metabolism. Therefore, we tested the hypothesis that dietary BBI affects energy-associated pathways in the D. melanogaster midgut. Through microarray and metabolomic analyses, we show that dietary BBI affects energy utilization pathways in the midgut cells of D. melanogaster. In addition, ultrastructure studies indicate that microvilli are significantly shortened in BBI-fed larvae. These data provide further insights into the complex cellular response of insects to dietary protease inhibitors.
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Affiliation(s)
- H-M Li
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Uncoupling of expression of an intronic microRNA and its myosin host gene by exon skipping. Mol Cell Biol 2010; 30:1937-45. [PMID: 20154144 DOI: 10.1128/mcb.01370-09] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The ancient MYH7b gene, expressed in striated muscle and brain, encodes a sarcomeric myosin and the intronic microRNA miR-499. We find that skipping of an exon introduces a premature termination codon in the transcript that downregulates MYH7b protein production without affecting microRNA expression. Among other genes, endogenous miR-499 targets the 3' untranslated region of the transcription factor Sox6, which in turn acts as a repressor of MYH7b transcriptional activity. Thus, concerted transcription and alternative splicing uncouple the level of expression of MYH7b and miR-499 when their coexpression is not required.
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Richer E, Campion CG, Dabbas B, White JH, Cellier MFM. Transcription factors Sp1 and C/EBP regulate NRAMP1 gene expression. FEBS J 2008; 275:5074-89. [PMID: 18786141 DOI: 10.1111/j.1742-4658.2008.06640.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The natural resistance-associated macrophage protein 1 (Nramp1), which belongs to a conserved family of membrane metal transporters, contributes to phagocyte-autonomous antimicrobial defense mechanisms. Genetic polymorphisms in the human NRAMP1 gene predispose to susceptibility to infectious or inflammatory diseases. To characterize the transcriptional mechanisms controlling NRAMP1 expression, we previously showed that a 263 bp region upstream of the ATG drives basal promoter activity, and that a 325 bp region further upstream confers myeloid specificity and activation during differentiation of HL-60 cells induced by vitamin D. Herein, the major transcription start site was mapped in the basal region by S1 protection assay, and two cis-acting elements essential for myeloid transactivation were characterized by in vitro DNase footprinting, electrophoretic mobility shift experiments, in vivo transfection assays using linker-mutated constructs, and chromatin immunoprecipitation assays in differentiated monocytic cells. One distal cis element binds Sp1 and is required for NRAMP1 myeloid regulation. Another site in the proximal region binds CCAAT enhancer binding proteins alpha or beta and is crucial for transcription. This study implicates Sp1 and C/EBP factors in regulating the expression of the NRAMP1 gene in myeloid cells.
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Affiliation(s)
- Etienne Richer
- Institut national de la recherche scientifique, INRS-Institut Armand-Frappier, Laval, Canada
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A transcriptional enhancer from the coding region of ADAMTS5. PLoS One 2008; 3:e2184. [PMID: 18478108 PMCID: PMC2364661 DOI: 10.1371/journal.pone.0002184] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Accepted: 04/02/2008] [Indexed: 01/12/2023] Open
Abstract
Background The revelation that the human genome encodes only ∼25,000 genes and thus cannot account for phenotypic complexity has been one of the biggest surprises in the post-genomic era. However, accumulating evidence suggests that transcriptional regulation may be in large part responsible for this observed mammalian complexity. Consequently, there has been a strong drive to locate cis-regulatory regions in mammalian genomes in order to understand the unifying principles governing these regions, including their genomic distribution. Although a number of systematic approaches have been developed, these all discount coding sequence. Methodology/Principal Findings Using the computational tool PRI (Pattern-defined Regulatory Islands), which does not mask coding sequence, we identified a regulatory region associated with the gene ADAMTS5 that encompasses the entirety of the essential coding exon 2. We demonstrate through a combination of chromatin immunoprecipitation and reporter gene studies that this region can not only bind the myogenic transcription factors MYOD and myogenin and the E-protein HEB but can also function as a very strong myogenic transcriptional enhancer. Conclusions/Significance Thus, we report the identification and detailed characterization of an exonic enhancer. Ultimately, this leads to the interesting question of why evolution would be so parsimonious in the functional assignment of sequence.
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