Early development of medaka Oryzias latipes muscles as revealed by transgenic approaches using embryonic and larval types of myosin heavy chain genes

Abstract

We cloned three full-length cDNAs encoding myosin heavy chains (MYHs) previously found to be expressed in embryos or larvae of medaka Oryzias latipes. Based on cDNA sequence information, the three medaka MYH genes, mMYH emb1 , mMYH L1 and mMYH L2 , were localized on the chromosomes. In vivo promoter assay using the gene encoding green or red fluorescent protein and linked to the 5 0 -flanking region of mMYH demonstrated that the transcripts of fast-type mMYH emb1 , first expressed in embryos but belonging to the adult type in phylogenetic analysis, were located in the horizontal myoseptum. On the other hand, embryonic fast-type mMYH L1 and mMYH L2 were expressed in the whole myotomes. Interestingly, cells expressing mMYH emb1 were localized together with engrailed, and cyclopamine, which blocks hedgehog signaling, inhibited mMYH emb1 expression as well as the formation of the horizontal myoseptum, suggesting that muscle pioneer cells express mMYH emb1 as a key protein in the formation of the horizontal myoseptum.

Evolution of the myosin heavy chain gene MYH14 and its intronic microRNA miR-499: muscle-specific miR-499 expression persists in the absence of the ancestral host gene

“…Medaka makes a particularly interesting subject because of the complete elimination of MYH14 from its genome. Although muscle fiber-type composition has not been well characterized in medaka, Ono et al [30] reported an MYH gene specifically expressed in slow muscle fibers at the horizontal myoseptum. Such MYH expression has never been reported in other teleost fish species.…”

“…Interestingly, sequence comparison analysis showed highly conserved 5′-flanking regions between torafugu MYH M5 and medaka miR-499 (see Figure 5A). The spatio-temporal expression of the major skeletal MYHs in teleost fish is regulated by small regions scattered throughout the 5′-flanking sequence [18,30,34,35]. Recently, Yeung et al [36] reported promoter activity in a 6.2-kb upstream sequence of mouse MYH14 that mimics endogenous MYH14 and miR-499 expression.…”

Lampreys Have a Single Gene Cluster for the Fast Skeletal Myosin Heavy Chain Gene Family

“…More diverse sarcomeric MYH s have been found in the fast muscle of teleosts, such as the common carp Cyprinus carpio [5-8], zebrafish Danio rerio [9-12], medaka Oryzias latipes [13-15] and torafugu Takifugu rubripes [16-19], at the genomic and transcriptional levels. In addition, genomic structural and syntenic analyses have revealed that at least 13 torafugu fast skeletal MYH s are distributed in 5 genomic regions, 3 of which contain multiple MYH s forming clusters A, B and C [18] (Figure S1).…”

“…In addition, genomic structural and syntenic analyses have revealed that at least 13 torafugu fast skeletal MYH s are distributed in 5 genomic regions, 3 of which contain multiple MYH s forming clusters A, B and C [18] (Figure S1). These clusters are also found in the green spotted pufferfish Tetraodon nigroviridis , zebrafish and medaka [12,15,18], implying that such genomic arrangement is conserved in teleosts. Interestingly, human fast skeletal MYH s form a single cluster, but their syntenic regions in torafugu, green spotted pufferfish and medaka are duplicated, although each locus contains a single MYH [18].…”

Multiple cis-elements in the 5′-flanking region of embryonic/larval fast-type of the myosin heavy chain gene of torafugu, MYHM743-2, function in the transcriptional regulation of its expression

“…Genomic structural analysis of torafugu revealed that fast-type MYHs in scaffold M743 (Fugu genome database Ver 3.0) form gene cluster C and are classified into an embryonic fast type (Ikeda et al, 2007) with its orthologous genes, all of which have also been reported to be expressed predominantly during embryonic and larval development in common carp (Nihei et al, 2006), medaka (Liang et al, 2007;Ono et al, 2006Ono et al, , 2010, and zebrafish Danio rerio (Berdougo et al, 2003;Bryson-Richardson et al, 2005;Wallace et al, 2005). The expression patterns of sarcomeric MYH M743-2 in early developmental stages of torafugu were analyzed by our laboratory members.…”