MOLECULAR CHARACTERIZATION OF A BMP2A HOMOLOGUE IN BARBEL STEED (HEMIBARBUS LABEO) AND ITS INVOLVEMENT IN INTERMUSCULAR BONE DEVELOPMENT

Bone morphogenetic protein (BMP) belongs to the transforming growth factor-beta (TGF-β) superfamily, and BMP2 is a secreted multifunctional protein with strong ability to induce bone formation. To explore the correlation between BMP2 and intermuscular bone development, the bmp2a cDNA of barbel steed (Hemibarbus labeo) was cloned and sequenced. The amino acid sequence alignment showed that the barbel steed BMP2A is highly conserved with other fishes, and they all have the highly conserved TGFβ domain in which an N-glycosylation site exists. In addition, fish BMP2 protein, including barbel steed BMP2A, have seven conserved cysteine residues. Phylogenetic tree analysis indicated that barbel steed BMP2A were closely related to that of Wuchang bream (Megalobrama amblycephala) BMP2A. The expression of barbel steed bmp2a transcripts was detected in all tested tissues, with the highest mRNA level in the gill, followed by the liver and muscle, and the lowest in the heart. Immunohistochemistry results showed that BMP2A protein was distributed in the myosepta. In addition, the expression of the bmp2a gene coincides with the development of intermuscular ossification. In summary, the high correlation between bmp2a gene and intermuscular ossification provides basic data for further investigation of the function of bmp2 gene and its regulation role in intermuscular bone development.