GPR35 Mediates the Proliferation and Adipogenesis of Goat Intramuscular Preadipocytes Through the cAMP/PKA Signaling Pathway

GPR35 is a member of the G-protein-coupled receptor family and existing studies have shown that its expression may be negatively correlated with fat deposition in mice. However, the exact role of GPR35 in goat intramuscular preadipocytes’ adipogenic differentiation remains unknown. This study is the first to demonstrate that GPR35 inhibits the maturation and differentiation of goat intramuscular preadipocytes via activating the cAMP/PKA signaling pathway under in vitro culture conditions. The functional experimental results showed that GPR35 overexpression suppressed the adipogenic differentiation, lipid synthesis, and proliferation capacity of goat intramuscular preadipocytes, and concurrently downregulated the expression of adipogenic differentiation marker genes and cell proliferation marker genes. Conversely, GPR35 knockdown promoted lipid accumulation, reduced intracellular cAMP levels, and ultimately enhanced the differentiation and proliferation capacity of intramuscular preadipocytes. Treatment with the cAMP inhibitor SQ22536 and PKA phosphorylation inhibitor H89 successfully reversed the phenotypic changes induced by GPR35 overexpression, including abnormal lipid droplet morphology, decreased triglyceride (TG) content, and inhibition of the expression of genes related to adipocyte differentiation/proliferation/metabolism (such as CDK2, PCNA, and HSL). These results confirm that GPR35 mainly regulates intramuscular fat deposition in goats through the cAMP/PKA pathway, providing a new target for elucidating the molecular mechanism of lipid metabolism and goat molecular breeding.