Molecular cloning, characterization, and expression of sheep FGF5 gene

The fibroblast growth factor 5 gene (FGF5) is a member of the FGF gene family, and represents a candidate gene for hair length because of its role in the regulation of the hair follicle growth cycle. In our current study, we cloned, sequenced, and characterized the full-length FGF5 cDNA of Chinese Merino sheep. We obtained the complete genomic sequence of the FGF5 gene from sheep blood samples, and compared it to other FGF5 sequences in GenBank. We found that the FGF5 gene spanned 21,743bp of genomic DNA, and consisted of 3 exons and 2 introns, both of which differed from those of a previously annotated FGF5 genomic sequence from sheep. We also identified a previously undescribed FGF5 mRNA splicing variant, FGF5S, and the western blot analysis showed that the molecular weights of the FGF5 (34kDa) and FGF5s (17kDa) proteins were consistent with the estimates based on the genomic and cDNA sequence data. We examined the expression of both FGF5 mRNAs in various tissues of sheep, and found that the expression of the FGF5S mRNA was restricted to the brain, spleen, and skin tissue. The single-nucleotide polymorphism analysis of the genomic sequence revealed 72 genetic variants of the FGF5 gene. Our findings provide insight into the functions of the FGF5 gene in Chinese Merino.