miRNA-223 targets the GPAM gene and regulates the differentiation of intramuscular adipocytes.

Intramuscular fat (IMF) has significant effects on the tenderness, juiciness, and flavor of chicken, which are important determinants of poultry meat quality. Although many studies have focused on microRNAs (miRNAs) involved in adipogenesis, little is known about miRNAs associated with poultry IMF deposition or intramuscular adipocyte differentiation. Bioinformatic analysis identified mitochondrial glycerol‑3‑phosphate acyltransferase (GPAM) as a putative target of miR-223. To explore the role of miR-223 in the process of chicken IMF deposition, loss and gain of function experiments were performed in primary intramuscular preadipocytes using miR-223 mimics, miR-223 inhibitor, and si-GPAM. Our results showed that miR-223 is significantly down-regulated in the breast muscle tissues of Gushi hens at the later-laying period in comparison with hens at the pre-laying period. Using qRT-PCR, we found that miR-223 expression in chicken tissues and intramuscular adipocytes correlates negatively with GPAM expression. Cell transfection experiments suggest that miR-223 inhibits intramuscular adipocyte differentiation via targeting GPAM. Experiments using a dual luciferase reporter system show that GPAM is a direct target of miR-223. Taken together, our results support the hypothesis that miR-223 regulates intramuscular fat deposition in chickens.