Effects of SPARCL1 on the proliferation and differentiation of sheep preadipocytes.

Important candidate genes that regulate lipid metabolism have the potential to increase the content of intramuscular fat (IMF) and improve meat quality. Secreted protein acidic and rich in cysteine like 1 ( SPARCL1 ) is a secreted glycoprotein with important physiological functions and is involved in the proliferation and differentiation of various cells. However, the role of the SPARCL1 gene in sheep preadipocytes and its regulatory mechanism is still unclear. In this study, we explored the effect of SPARCL1 on the proliferation and differentiation of sheep preadipocytes. The results showed that the expression level of the SPARCL1 gene is higher in fat tissue than in other tissues, and the gene was significantly increased on the 6 th day of preadipocyte differentiation. In the preadipocyte proliferation stage, interference of SPARCL1 gene reduced cell viability and increased cell apoptosis. In preadipocyte differentiation stage, SPARCL1 overexpression significantly inhibited lipid droplets accumulation and triglyceride content by increasing Wnt10b, Fzd8, IL6 , and β-catenin and inhibiting PPARγ, C/EBPα, LPL , and IGF1 genes expression, whereas SPARCL1 deficiency significantly promoted cell differentiation by inhibiting β-catenin and increasing GSK3β, PPARγ, C/EBPα , and LPL . The results of this study suggest that SPARCL1 plays a negative role during preadipocyte differentiation and may become a novel target for regulating preadipocyte differentiation and improving IMF. Abbreviations: IMF : Intramuscular fat SPARCL1 : Secreted protein acidic and rich in cysteine like 1 PPARγ : Peroxisome proliferator-activated receptor γ C/EBPα : CCAAT/enhancer-binding protein-α LPL : Lipoprotein lipase IGF1 : Insulin-like growth factor 1 Wnt10b : Wnt family member 10B Fzd8 : Frizzled class receptor 8 IL6 : Interleukin 6 β-catenin : Catenin beta interacting protein 1 GSK3β : Glycogen synthase kinase 3 beta LRP5/6 : Low-density lipoprotein receptor-related protein 5/6.