title: Expression pattern of muscleblind-like proteins differs in differentiating myoblasts.
abstract: Muscleblind-like (MBNL) proteins are believed to be regulators of myogenesis and are implicated in myotonic dystrophy. While Drosophila melanogaster muscleblind is required for terminal muscle differentiation, mammalian MBNL3 functions as an inhibitor of myogenesis. In this study, we analyzed the expression pattern of MBNL3 in different adult mouse tissues and tissue culture cells. MBNL3 transcript is enriched in the lung, spleen, and testis and not in heart and skeletal muscle. By Western blotting, we found that MBNL3 was expressed in C2C12 myoblasts and ts13 myofibroblasts, but was detected at significantly lower levels in fibroblasts. MBNL3 protein levels decreased when cells were shifted to muscle differentiation conditions, but the closely related MBNL1 protein was unaffected. These results suggest that myoblasts and fibroblasts respond to differentiation conditions by activating signaling pathways that repress MBNL3 but not MBNL1 expression.
authors.affiliation: University of Washington, School of Medicine, Department of Pharmacology, Seattle, 1959 NE Pacific Street, Box 357280, WA 98195-7280, USA.
authors.forename: Kyung-Soon
authors.initials: KS
authors.lastname: Lee
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Squillace
authors.forename: Edith H
authors.initials: EH
authors.lastname: Wang
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D051379:Mice; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C522920:MBNL3 protein, mouse; C479922:Mbnl1 protein, mouse; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins