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