Spatial and temporal expression of bmp8a and its role in regulation of lipid metabolism in zebrafish Danio rerio

Bone morphogenetic proteins (BMP) are members of the transforming growth factor beta (TGF-β) superfamily. BMP8a and BMP8b have different functions in mammals. However, only one bmp8 gene is present in zebrafish Danio rerio, so we are interested to investigate the function and evolution of this gene. The zebrafish bmp8 gene was identified to represent the bmp8a ortholog (zbmp8a) but not the bmp8b ortholog. In adult zebrafish, the zbmp8a mRNA was highly expressed in the tissues of intestine, testis, skin and brain; during embryogenesis, zbmp8a was present in all cells at early stages and then mainly restricted to the head region and intestine at late stages. Furthermore, the zbmp8a expression was decreased during fasting and increased dramatically after refeeding. In high-fat diet induced obese zebrafish, the expression of zbmp8a was up-regulated significantly. In addition, temperature and salinity affected the transcript levels of zbmp8a. Importantly, the recombinant mature peptide of zBmp8a was administered by microinjection to yolk sac of 3-dpf larvae, resulting that the lipidolysis was accelerated. Besides, zBmp8a protein increased the expression levels of pgc-1α, pgc-1β, ucp1, ucp2, pparαa, pparαb, pparβ, pparγ, leptin and lpl. These results demonstrate that zbmp8a is involved in the regulation of lipid metabolism in zebrafish. Our finding provides the first data about the role of bmp8a in energy homeostasis in teleost.