Genome-wide characteristic and functional analyses of the BMP gene family reveal its role in response to directed selection in chicken (Gallus gallus)

The bone morphogenetic protein (BMP) gene family comprises a group of multifunctional cytokines that play important roles in limb development, bone formation, fat deposition, and reproductive traits of vertebrates. However, no systematic and comprehensive investigations of the various traits of the whole family members have been conducted, particularly in chickens. Here, we performed genome-wide screening and identified 14 BMP genes, which were classified into the BMP2/4, BMP5/6/7/8A, growth differentiation factor (GDF) 2/BMP10, GDF5/6/7, and GDF11/BMP3/15 subfamilies. Genetic variation pattern analysis showed that BMP genes were responsible for the artificial selection of commercial broilers and layers, with BMP2, BMP6, and GDF7 likely contributing significantly to the formation of both specialized meat- and eggtype lines, whereas BMP7 likely contributed more to the formation of meat-type lines. Genetic association analysis showed that single nucleotide polymorphisms (SNPs) in the BMP7 intron region were associated with body weight, breast muscle weight, leg weight, abdominal fat weights and contents of total cholesterol (T-CHO), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) in serum. Additionally, gain- and loss-of-function assays demonstrated that BMP7 promoted the proliferation, myogenic differentiation, and lipid droplet accumulation in myoblasts; enhanced lipid synthesis in hepatocytes; promoted the proliferation and inhibited adipogenic differentiation of intramuscular preadipocytes; and induced the proliferation and adipogenic differentiation of abdominal preadipocytes. These results provide novel insights into the role of BMP genes in chicken growth, reproductive regulation, and lipid deposition and could be used to develop genetic markers for breeding selection in chickens.