title: Regulation of gene expression mediating indeterminate muscle growth in teleosts.
abstract: Teleosts are unique among vertebrates due to their indeterminate muscle growth, i.e., continued production of neonatal muscle fibers until death. However, the molecular mechanism(s) underlying this property is unknown. Here, we focused on the torafugu (Takifugu rubripes) myosin heavy chain gene, MYHM2528-1, which is specifically expressed in neonatal muscle fibers produced by indeterminate muscle growth. We examined the flanking region of MYHM2528-1 through an in vivo reporter assay using zebrafish (Danio rerio) and identified a 2100 bp 5'-flanking sequence that contained sufficient promoter activity to allow specific gene expression. The effects of enhanced promoter activity were observed at the outer region of the fast muscle and the dorsal edge of slow muscle in zebrafish larvae. At the juvenile stage, the promoter was specifically activated in small diameter muscle fibers scattered throughout fast muscle and in slow muscle near the septum separating slow and fast muscles. This spatio-temporal promoter activity overlapped with known myogenic zones involved in teleost indeterminate muscle growth. A deletion mutant analysis revealed that the -2100 to -600 bp 5'flanking sequence of MYHM2528-1 is essential for promoter activity. This region contains putative binding sites for several representative myogenesis-related transcription factors and nuclear factor of activated T-cell (NFAT), a transcription activator involved in regeneration of mammalian adult skeletal muscle. A significant reduction in the promoter activity of the MYHM2528-1 deletion constructs was observed in accordance with a reduction in the number of these binding sites, suggesting the involvement of specific transcription factors in indeterminate muscle growth.
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: A K Shakur
authors.initials: AK
authors.lastname: Ahammad
authors.affiliation: School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, 21030 Kuala-Terengganu, Terengganu, Malaysia.
authors.forename: Md
authors.initials: M
authors.lastname: Asaduzzaman
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Asakawa
authors.affiliation: School of Marine Biosciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan.
authors.forename: Shugo
authors.initials: S
authors.lastname: Watabe
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan. Electronic address: akino@mail.ecc.u-tokyo.ac.jp.
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Kinoshita
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D007814:Larva / Q000502:physiology; D024510:Muscle Development / Q000235:genetics* / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology*; D018006:Myogenic Regulatory Factors / Q000235:genetics; D018995:Myosin Heavy Chains / Q000235:genetics / Q000502:physiology; D050778:NFATC Transcription Factors / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics; D023741:Takifugu / Q000235:genetics* / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics; D015027:Zebrafish / Q000235:genetics
chemical_list: D018006:Myogenic Regulatory Factors; D050778:NFATC Transcription Factors; D014157:Transcription Factors; D018995:Myosin Heavy Chains
keywords: Indeterminate muscle growth; Muscle hyperplasia; Myosin heavy chain; Promoter analysis; Teleost