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Vicente-García C, Hernández-Camacho JD, Carvajal JJ. Regulation of myogenic gene expression. Exp Cell Res 2022; 419:113299. [DOI: 10.1016/j.yexcr.2022.113299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 12/22/2022]
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Nipun VB, Amin KA. Recent Advances in Protein Kinase CK2, a Potential Therapeutic Target in Cancer. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2022; 48:919-931. [DOI: 10.1134/s1068162022050144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- V. B. Nipun
- Cancer Research Center, Shantou University Medical Collage, Shantou, Guangdong, 515041, PR China
- Department of Chemistry, Faculty of Science, University of Imam Abdulrahman Bin Faisal university, P.O. Box 1982, Dammam, 31441, Saudi Arabia
| | - K. A. Amin
- Department of Chemistry, Faculty of Science, University of Imam Abdulrahman Bin Faisal university, P.O. Box 1982, Dammam, 31441, Saudi Arabia
- Basic and Applied Scientific Research Center, Imam Abdulrahman Bin Faisal university, P.O. Box 1982, Dammam, 31441, Saudi Arabia
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Chen X, Sun Y, Zhang T, Roepstorff P, Yang F. Comprehensive Analysis of the Proteome and PTMomes of C2C12 Myoblasts Reveals that Sialylation Plays a Role in the Differentiation of Skeletal Muscle Cells. J Proteome Res 2020; 20:222-235. [PMID: 33216553 DOI: 10.1021/acs.jproteome.0c00353] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The C2C12 myoblast is a model that has been used extensively to study the process of skeletal muscle differentiation. Proteomics has advanced our understanding of skeletal muscle biology and also the differentiation process of skeletal muscle cells. However, there is still no comprehensive analysis of C2C12 myoblast proteomes, which is important for the understanding of key drivers for the differentiation of skeletal muscle cells. Here, we conducted multidimensional proteome profiling to get a comprehensive analysis of proteomes and PTMomes of C2C12 myoblasts with a TiSH strategy. A total of 8313 protein groups were identified, including 7827 protein groups from nonmodified peptides, 3803 phosphoproteins, and 977 formerly sialylated N-linked glycoproteins. Integrated analysis of proteomic and PTMomic data showed that almost all of the kinases and transcription factors in the muscle cell differentiation pathway were phosphorylated. Further analysis indicated that sialylation might play a role in the differentiation of C2C12 myoblasts. Further functional analysis demonstrated that C2C12 myoblasts showed a decreased level of sialylation during skeletal muscle cell differentiation. Inhibition of sialylation with the sialyltransferase inhibitor 3Fax-Neu5Ac resulted in the lower expression of MHC and suppression of myoblast fusion. In all, these results indicate that sialylation has an effect on the differentiation of skeletal muscle cells.
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Affiliation(s)
- Xiulan Chen
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100149, China
| | - Yaping Sun
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100149, China
| | - Tingting Zhang
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100149, China
| | - Peter Roepstorff
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Fuquan Yang
- Key Laboratory of Protein and Peptide Pharmaceuticals & Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100149, China
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Regulation of the Mammalian SWI/SNF Family of Chromatin Remodeling Enzymes by Phosphorylation during Myogenesis. BIOLOGY 2020; 9:biology9070152. [PMID: 32635263 PMCID: PMC7407365 DOI: 10.3390/biology9070152] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/24/2020] [Accepted: 07/01/2020] [Indexed: 11/16/2022]
Abstract
Myogenesis is the biological process by which skeletal muscle tissue forms. Regulation of myogenesis involves a variety of conventional, epigenetic, and epigenomic mechanisms that control chromatin remodeling, DNA methylation, histone modification, and activation of transcription factors. Chromatin remodeling enzymes utilize ATP hydrolysis to alter nucleosome structure and/or positioning. The mammalian SWItch/Sucrose Non-Fermentable (mSWI/SNF) family of chromatin remodeling enzymes is essential for myogenesis. Here we review diverse and novel mechanisms of regulation of mSWI/SNF enzymes by kinases and phosphatases. The integration of classic signaling pathways with chromatin remodeling enzyme function impacts myoblast viability and proliferation as well as differentiation. Regulated processes include the assembly of the mSWI/SNF enzyme complex, choice of subunits to be incorporated into the complex, and sub-nuclear localization of enzyme subunits. Together these processes influence the chromatin remodeling and gene expression events that control myoblast function and the induction of tissue-specific genes during differentiation.
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Hashemolhosseini S. The role of protein kinase CK2 in skeletal muscle: Myogenesis, neuromuscular junctions, and rhabdomyosarcoma. Neurosci Lett 2020; 729:135001. [DOI: 10.1016/j.neulet.2020.135001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 01/08/2023]
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Padilla-Benavides T, Haokip DT, Yoon Y, Reyes-Gutierrez P, Rivera-Pérez JA, Imbalzano AN. CK2-Dependent Phosphorylation of the Brg1 Chromatin Remodeling Enzyme Occurs during Mitosis. Int J Mol Sci 2020; 21:ijms21030923. [PMID: 32019271 PMCID: PMC7036769 DOI: 10.3390/ijms21030923] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 11/16/2022] Open
Abstract
Brg1 (Brahma-related gene 1) is one of two mutually exclusive ATPases that can act as the catalytic subunit of mammalian SWI/SNF (mSWI/SfigureNF) chromatin remodeling enzymes that facilitate utilization of the DNA in eukaryotic cells. Brg1 is a phospho-protein, and its activity is regulated by specific kinases and phosphatases. Previously, we showed that Brg1 interacts with and is phosphorylated by casein kinase 2 (CK2) in a manner that regulates myoblast proliferation. Here, we use biochemical and cell and molecular biology approaches to demonstrate that the Brg1-CK2 interaction occurred during mitosis in embryonic mouse somites and in primary myoblasts derived from satellite cells isolated from mouse skeletal muscle tissue. The interaction of CK2 with Brg1 and the incorporation of a number of other subunits into the mSWI/SNF enzyme complex were independent of CK2 enzymatic activity. CK2-mediated hyperphosphorylation of Brg1 was observed in mitotic cells derived from multiple cell types and organisms, suggesting functional conservation across tissues and species. The mitotically hyperphosphorylated form of Brg1 was localized with soluble chromatin, demonstrating that CK2-mediated phosphorylation of Brg1 is associated with specific partitioning of Brg1 within subcellular compartments. Thus, CK2 acts as a mitotic kinase that regulates Brg1 phosphorylation and subcellular localization.
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Affiliation(s)
- Teresita Padilla-Benavides
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
| | - Dominic T. Haokip
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
| | - Yeonsoo Yoon
- Department of Pediatrics, Division of Genes and Development, University of Massachusetts Medical School, Worcester, MA 01655, USA; (Y.Y.); (J.A.R.-P.)
| | - Pablo Reyes-Gutierrez
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
| | - Jaime A. Rivera-Pérez
- Department of Pediatrics, Division of Genes and Development, University of Massachusetts Medical School, Worcester, MA 01655, USA; (Y.Y.); (J.A.R.-P.)
| | - Anthony N. Imbalzano
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
- Correspondence: ; Tel.: +1-508-856-1029
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Salizzato V, Zanin S, Borgo C, Lidron E, Salvi M, Rizzuto R, Pallafacchina G, Donella-Deana A. Protein kinase CK2 subunits exert specific and coordinated functions in skeletal muscle differentiation and fusogenic activity. FASEB J 2019; 33:10648-10667. [PMID: 31268746 PMCID: PMC6766657 DOI: 10.1096/fj.201801833rr] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 06/04/2019] [Indexed: 01/01/2023]
Abstract
Casein kinase 2 (CK2) is a tetrameric protein kinase composed of 2 catalytic (α and α') and 2 regulatory β subunits. Our study provides the first molecular and cellular characterization of the different CK2 subunits, highlighting their individual roles in skeletal muscle specification and differentiation. Analysis of C2C12 cell knockout for each CK2 subunit reveals that: 1) CK2β is mandatory for the expression of the muscle master regulator myogenic differentiation 1 in proliferating myoblasts, thus controlling both myogenic commitment and subsequent muscle-specific gene expression and myotube formation; 2) CK2α is involved in the activation of the muscle-specific gene program; and 3) CK2α' activity regulates myoblast fusion by mediating plasma membrane translocation of fusogenic proteins essential for membrane coalescence, like myomixer. Accordingly, CK2α' overexpression in C2C12 cells and in mouse regenerating muscle is sufficient to increase myofiber size and myonuclei content via enhanced satellite cell fusion. Consistent with these results, pharmacological inhibition of CK2 activity substantially blocks the expression of myogenic markers and muscle cell fusion both in vitro in C2C12 and primary myoblasts and in vivo in mouse regenerating muscle and zebrafish development. Overall, our work describes the specific and coordinated functions of CK2 subunits in orchestrating muscle differentiation and fusogenic activity, highlighting CK2 relevance in the physiopathology of skeletal muscle tissue.-Salizzato, V., Zanin, S., Borgo, C., Lidron, E., Salvi, M., Rizzuto, R., Pallafacchina, G., Donella-Deana, A. Protein kinase CK2 subunits exert specific and coordinated functions in skeletal muscle differentiation and fusogenic activity.
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Affiliation(s)
- Valentina Salizzato
- Department of Biomedical Sciences, University of Padua, Padua, Italy
- Italian National Research Council (CNR) Neuroscience Institute, Padua, Italy
| | - Sofia Zanin
- Department of Medicine, University of Padua, Padua, Italy
| | - Christian Borgo
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Elisa Lidron
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Mauro Salvi
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Giorgia Pallafacchina
- Department of Biomedical Sciences, University of Padua, Padua, Italy
- Italian National Research Council (CNR) Neuroscience Institute, Padua, Italy
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8
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Götz C, Montenarh M. Protein kinase CK2 in development and differentiation. Biomed Rep 2016; 6:127-133. [PMID: 28357063 DOI: 10.3892/br.2016.829] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/06/2016] [Indexed: 12/15/2022] Open
Abstract
Among the human kinomes, protein kinase CK2 (formerly termed casein kinase II) is considered to be essential, as it is implicated in the regulation of various cellular processes. Experiments with pharmacological inhibitors of the kinase activity of CK2 provide evidence that CK2 is essential for development and differentiation. Therefore, the present review addresses the role of CK2 during embryogenesis, neuronal, adipogenic, osteogenic and myogenic differentiation in established model cell lines, and in embryonic, neural and mesenchymal stem cells. CK2 kinase activity appears to be essential in the early stages of differentiation, as CK2 inhibition at early time points generally prevents differentiation. In addition, the present review reports on target proteins of CK2 in embryogenesis and differentiation.
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Affiliation(s)
- Claudia Götz
- Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66424 Homburg, Germany
| | - Mathias Montenarh
- Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66424 Homburg, Germany
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Oncorhynchus mykiss pax7 sequence variations with comparative analyses against other teleost species. SPRINGERPLUS 2015; 4:263. [PMID: 26090310 PMCID: PMC4469688 DOI: 10.1186/s40064-015-1030-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 05/12/2015] [Indexed: 12/24/2022]
Abstract
The paired box-7 (pax7) transcription factor expressed in satellite cells (SCs) is an essential regulator of skeletal muscle growth and regeneration in vertebrates including fish. Characterization of rainbow trout (Oncorhynchus mykiss) pax7 gene/s may offer novel insights into skeletal myogenesis by SCs in this indeterminate growth species. Further, evaluation of promoters for cis-regulatory regions may shed light on the evolutionary fate of the duplicated genes. Employing standard PCR, cloning and computational approach, we identified and report complete coding sequences of two pax7 paralogs of rainbow trout (rt); rtpax7α and rtpax7β. Both genes show significant identity in the nucleotide (97%) and the predicted amino acid (98%) sequences, and bear the characteristic paired domain (PD), octapeptide (OP) and homeodomain (HD) motifs. We further report several splice variants of each gene and nucleotide differences in coding sequence that predicts six putative amino acid changes between the two genes. Additionally, we noted a trinucleotide deletion in rtpax7β that results in putative serine elimination at the N-terminus and a single nucleotide polymorphism (SNP) in majority of the rtpax7β variants (6/10) that predicts an arginine substitution for a lysine. We also deciphered the genomic organization up to the first three exons and the upstream putative promoter regions of both genes. Comparative in silico analysis of both the trout pax7 promoters with that of zebrafish pax7 duplicates; zfpax7a and zfpax7b; predicts several important cis-elements/transcription factor binding sites (TFBS) in these teleost pax7 promoter regions.
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Wang M, Amano SU, Flach RJR, Chawla A, Aouadi M, Czech MP. Identification of Map4k4 as a novel suppressor of skeletal muscle differentiation. Mol Cell Biol 2013; 33:678-87. [PMID: 23207904 PMCID: PMC3571342 DOI: 10.1128/mcb.00618-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 11/20/2012] [Indexed: 12/19/2022] Open
Abstract
Myoblast differentiation into mature myotubes is a critical step in the development and repair of human skeletal muscle. Here we show that small interfering RNA (siRNA)-based silencing of the Ste20-like mitogen-activated protein 4 kinase 4 (Map4k4) in C2C12 myoblasts markedly enhances expression of myogenic differentiation genes, myoblast fusion, and myotube diameter. In contrast, adenovirus-mediated expression of native Map4k4 in C2C12 cells attenuates each of these processes, indicating that Map4k4 is a negative regulator of myogenic differentiation and hypertrophy. Expression of a Map4k4 kinase-inactive mutant enhances myotube formation, suggesting that the kinase activity of Map4k4 is essential for its inhibition of muscle differentiation. Map4k4 regulation of myogenesis is unlikely to be mediated by classic mitogen-activated protein kinase (MAPK) signaling pathways, because no significant difference in phosphorylation of extracellular signal-regulated kinase (ERK), p38, or c-Jun N-terminal kinase (JNK) is observed in Map4k4-silenced cells. Furthermore, silencing of these other MAPKs does not result in a hypertrophic myotube phenotype like that seen with Map4k4 depletion. Uniquely, Map4k4 silencing upregulates the expression of the myogenic regulatory factor Myf5, whose depletion inhibits myogenesis. Furthermore, Myf5 is required for enhancement of myotube formation in Map4k4-silenced cells, while Myf5 overexpression rescues Map4k4-mediated inhibition of myogenic differentiation. These results demonstrate that Map4k4 is a novel suppressor of skeletal muscle differentiation, acting through a Myf5-dependent mechanism.
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Affiliation(s)
- Mengxi Wang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Dietz KN, Miller PJ, Hollenbach AD. Phosphorylation of serine 205 by the protein kinase CK2 persists on Pax3-FOXO1, but not Pax3, throughout early myogenic differentiation. Biochemistry 2010; 48:11786-95. [PMID: 19904978 DOI: 10.1021/bi9012947] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The myogenic transcription factor Pax3 plays an essential role in early skeletal muscle development and is a key component in alveolar rhabdomyosarcoma (ARMS), a childhood solid muscle tumor. ARMS is characterized by a t(2;13) chromosomal translocation resulting in the fusion of the 5' Pax3 sequences to the 3' FOXO1 sequences to encode the oncogenic fusion protein, Pax3-FOXO1. Posttranslational modifications such as phosphorylation are common mechanisms by which transcription factors are regulated. Consistent with this fact, we demonstrated in a previous report that Pax3 is phosphorylated on Ser205 in proliferating, but not differentiated, primary myoblasts. However, the kinase that mediates this phosphorylation event has yet to be identified. In addition, it is not known whether Pax3-FOXO1 is phosphorylated at this site or how the phosphorylation of the fusion protein changes during early myogenic differentiation. In this report we identify CK2 (formerly termed "casein kinase II") as the kinase responsible for phosphorylating Pax3 and Pax3-FOXO1 at Ser205 in proliferating mouse primary myoblasts. Furthermore, we demonstrate that, in contrast to wild-type Pax3, phosphorylation at Ser205 persists on Pax3-FOXO1 throughout early myogenic differentiation. Finally, we show that Pax3-FOXO1 is phosphorylated at Ser205 in a variety of translocation-containing ARMS cell lines. The results presented in this report not only suggest a possible mechanism by which the disregulation of Pax3-FOXO1 may contribute to tumorigenesis but also identify a novel target for the development of therapies for the treatment of ARMS.
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Affiliation(s)
- Kevin N Dietz
- Department of Genetics, Louisiana State University Health Sciences Center, 533 Bolivar Street, New Orleans, Louisiana 70112, USA
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Abstract
The transcription factor DeltaFosB (also referred to as FosB2 or FosB[short form]) is an important mediator of the long-term plasticity induced in brain by chronic exposure to several types of psychoactive stimuli, including drugs of abuse, stress, and electroconvulsive seizures. A distinct feature of DeltaFosB is that, once induced, it persists in brain for relatively long periods of time in the absence of further stimulation. The mechanisms underlying this apparent stability, however, have remained unknown. Here, we demonstrate that DeltaFosB is a relatively stable transcription factor, with a half-life of approximately 10 h in cell culture. Furthermore, we show that DeltaFosB is a phosphoprotein in brain and that phosphorylation of a highly conserved serine residue (Ser27) in DeltaFosB protects it from proteasomal degradation. We provide several lines of evidence suggesting that this phosphorylation is mediated by casein kinase 2. These findings constitute the first evidence that DeltaFosB is phosphorylated and demonstrate that phosphorylation contributes to its stability, which is at the core of its ability to mediate long-lasting adaptations in brain.
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Bai Q, McGillivray C, da Costa N, Dornan S, Evans G, Stear MJ, Chang KC. Development of a porcine skeletal muscle cDNA microarray: analysis of differential transcript expression in phenotypically distinct muscles. BMC Genomics 2003; 4:8. [PMID: 12611633 PMCID: PMC152649 DOI: 10.1186/1471-2164-4-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2002] [Accepted: 03/01/2003] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Microarray profiling has the potential to illuminate the molecular processes that govern the phenotypic characteristics of porcine skeletal muscles, such as hypertrophy or atrophy, and the expression of specific fibre types. This information is not only important for understanding basic muscle biology but also provides underpinning knowledge for enhancing the efficiency of livestock production. RESULTS We report on the de novo development of a composite skeletal muscle cDNA microarray, comprising 5500 clones from two developmentally distinct cDNA libraries (longissimus dorsi of a 50-day porcine foetus and the gastrocnemius of a 3-day-old pig). Clones selected for the microarray assembly were of low to moderate abundance, as indicated by colony hybridisation. We profiled the differential expression of genes between the psoas (red muscle) and the longissimus dorsi (white muscle), by co-hybridisation of Cy3 and Cy5 labelled cDNA derived from these two muscles. Results from seven microarray slides (replicates) correctly identified genes that were expected to be differentially expressed, as well as a number of novel candidate regulatory genes. Quantitative real-time RT-PCR on selected genes was used to confirm the results from the microarray. CONCLUSION We have developed a porcine skeletal muscle cDNA microarray and have identified a number of candidate genes that could be involved in muscle phenotype determination, including several members of the casein kinase 2 signalling pathway.
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Affiliation(s)
- Qianfan Bai
- Laboratory of Veterinary Molecular Medicine, Department of Veterinary Pathology, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Christine McGillivray
- Laboratory of Veterinary Molecular Medicine, Department of Veterinary Pathology, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Nuno da Costa
- Laboratory of Veterinary Molecular Medicine, Department of Veterinary Pathology, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Saffron Dornan
- Sygen International, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Gary Evans
- Sygen International, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Michael James Stear
- Laboratory of Veterinary Molecular Medicine, Department of Veterinary Pathology, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
| | - Kin-Chow Chang
- Laboratory of Veterinary Molecular Medicine, Department of Veterinary Pathology, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK
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Winter B, Arnold HH. Activated raf kinase inhibits muscle cell differentiation through a MEF2-dependent mechanism. J Cell Sci 2000; 113 Pt 23:4211-20. [PMID: 11069766 DOI: 10.1242/jcs.113.23.4211] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Muscle cell development is dependent on the activity of cell type-specific basic-helix-loop-helix transcription factors, MyoD, Myf-5, myogenin, and MRF4 which collaborate with myocyte enhancer factor 2 proteins to activate muscle-specific gene expression. Growth factors and activated Ras prevent differentiation of myoblasts in culture but the downstream signalling pathways are not well understood. Here, we demonstrate that active Raf kinase (Raf-BxB) completely inhibits myogenic conversion of 10T1/2 cells mediated by Myf-5 and differentiation of L6 myoblasts as indicated by the absence of myotubes, lack of myogenin expression, and markedly reduced expression of myosin heavy chain. However, activated Raf inhibits transcriptional activation by Myf-5 only partially suggesting that other potential targets of Ras/Raf signalling may be involved. Significantly, we observed that elevated Raf kinase activity in L6 muscle cells suppresses the accumulation of MEF2 protein in nuclei, while MEF2 transcription appears unaffected. Moreover, forced expression of MEF2A in 10T1/2 cells rescues MyoD dependent myogenic conversion in the presence of constitutively active Raf kinase and partially restores transactivation of a myogenin promoter-dependent reporter gene in L6 muscle cells containing activated Raf kinase. From these observations we conclude that persistent activation of Raf signalling affects nuclear MEF2 functions which may explain why myogenin expression and myoblast differentiation are inhibited.
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Affiliation(s)
- B Winter
- Department of Cell and Molecular Biology, University of Braunschweig, Spielmannstr. 7, D-38106 Braunschweig, Germany.
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Puri PL, Sartorelli V. Regulation of muscle regulatory factors by DNA-binding, interacting proteins, and post-transcriptional modifications. J Cell Physiol 2000; 185:155-73. [PMID: 11025438 DOI: 10.1002/1097-4652(200011)185:2<155::aid-jcp1>3.0.co;2-z] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Skeletal muscle differentiation is influenced by multiple pathways, which regulate the activity of myogenic regulatory factors (MRFs)-the myogenic basic helix-loop-helix proteins and the MEF2-family members-in positive or negative ways. Here we will review and discuss the network of signals that regulate MRF function during myocyte proliferation, differentiation, and post-mitotic growth. Elucidating the mechanisms governing muscle-specific transcription will provide important insight in better understanding the embryonic development of muscle at the molecular level and will have important implications in setting out strategies aimed at muscle regeneration. Since the activity of MRFs are compromised in tumors of myogenic derivation-the rhabdomyosarcomas-the studies summarized in this review can provide a useful tool to uncover the molecular basis underlying the formation of these tumors.
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Affiliation(s)
- P L Puri
- Department of Biology, University of California San Diego, La Jolla, California, USA.
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Abstract
Protein kinase CK2 is a pleiotropic, ubiquitous and constitutively active protein kinase that can use both ATP and GTP as phosphoryl donors with specificity for serine/threonine residues in the vicinity of acidic amino acids. Recent results show that the enzyme is involved in transcription, signaling, proliferation and in various steps of development. The tetrameric holoenzyme (alpha2beta2) consists of two catalytic alpha-subunits and two regulatory beta-subunits. The structure of the catalytic subunit with the fixed positioning of the activation segment in the active conformation through its own aminoterminal region suggests a regulation at the transcriptional level making a regulation by second messengers unlikely. The high conservation of the catalytic subunit from yeast to man and its role in the tetrameric complex supports this notion. The regulatory beta-subunit has been far less conserved throughout evolution. Furthermore the existence of different CK2beta-related proteins together with the observation of deregulated CK2beta levels in tumor cells and the reported association of CK2beta protein with key proteins in signal transduction, e.g. A-Raf, Mos, pg90rsk etc. are suggestive for an additional physiological role of CK2beta protein beside being the regulatory compound in the tetrameric holoenzyme.
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Affiliation(s)
- B Guerra
- Biokemisk Institut, Odense Universitet, Denmark
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