title: Lampreys have a single gene cluster for the fast skeletal myosin heavy chain gene family.
abstract: Muscle tissues contain the most classic sarcomeric myosin, called myosin II, which consists of 2 heavy chains (MYHs) and 4 light chains. In the case of humans (tetrapod), a total of 6 fast skeletal-type MYH genes (MYHs) are clustered on a single chromosome. In contrast, torafugu (teleost) contains at least 13 fast skeletal MYHs, which are distributed in 5 genomic regions; the MYHs are clustered in 3 of these regions. In the present study, the evolutionary relationship among fast skeletal MYHs is elucidated by comparing the MYHs of teleosts and tetrapods with those of cyclostome lampreys, one of two groups of extant jawless vertebrates (agnathans). We found that lampreys contain at least 3 fast skeletal MYHs, which are clustered in a head-to-tail manner in a single genomic region. Although there was apparent synteny in the corresponding MYH cluster regions between lampreys and tetrapods, phylogenetic analysis indicated that lamprey and tetrapod MYHs have independently duplicated and diversified. Subsequent transgenic approaches showed that the 5'-flanking sequences of Japanese lamprey fast skeletal MYHs function as a regulatory sequence to drive specific reporter gene expression in the fast skeletal muscle of zebrafish embryos. Although zebrafish MYH promoters showed apparent activity to direct reporter gene expression in myogenic cells derived from mice, promoters from Japanese lamprey MYHs had no activity. These results suggest that the muscle-specific regulatory mechanisms are partially conserved between teleosts and tetrapods but not between cyclostomes and tetrapods, despite the conserved synteny.
authors.affiliation: School of Marine Biosciences, Kitasato University, Sagamihara, Kanagawa, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ikeda
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Ono
authors.affiliation: Department of Medical Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Hirano
authors.affiliation: School of Marine Biosciences, Kitasato University, Sagamihara, Kanagawa, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Kan-no
authors.affiliation: School of Marine Biosciences, Kitasato University, Sagamihara, Kanagawa, Japan ; Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Shugo
authors.initials: S
authors.lastname: Watabe
mesh_terms: D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D017931:DNA Primers / Q000235:genetics; D019143:Evolution, Molecular; D007150:Immunohistochemistry; D007564:Japan; D007798:Lampreys / Q000235:genetics*; D016013:Likelihood Functions; D008156:Luciferases; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D018656:Muscle Fibers, Fast-Twitch; D018995:Myosin Heavy Chains / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014714:Vertebrates / Q000235:genetics*
chemical_list: D017931:DNA Primers; D008156:Luciferases; D018995:Myosin Heavy Chains