Molecular cloning,characterization and functional assessment of the myosin light polypeptide chain 2 (mylz2) promoter of farmed carp,Labeo rohita

We cloned the 5′-flanking region (1.2 kb) of a muscle-specific gene, encoding myosin light chain 2 polypeptide (mylz2) of a farmed carp, Labeo rohita (rohu). Sequence analysis using TRANSFAC-database search identified the consensus cis acting regulatory elements of TATA-box and E (CANNTG)-box, including the monocyte enhancer factor 2 motif, implying that it is likely to be a functional promoter. The proximal promoter (~620 bp) was highly homologous with that of Danio rerio (zebrafish) as compared to Channa striatus (snakehead murrel) counterparts and showed less identity with Sparus auratus (gilthead sea bream), Xenopus laevis (African clawed frog) and Rattus norvegicus (Norway rat). Direct muscular (skeletal) injection of the construct containing the mylz2 promoter (0.6 kb) fused to a green fluorescent protein (GFP) reporter gene showed efficient expression in L. rohita, validating its functional activity. Further, the functional activity was confirmed by the observation that this promoter drove GFP expression in the skeletal muscle of transgenic rohu. The promoter may have potential applications for value-addition in ornamental fishes and studying gene regulatory functions.