MicroRNA-125a-5p Affects Adipocytes Proliferation, Differentiation and Fatty Acid Composition of Porcine Intramuscular Fat.

Jingjing Du,Jideng Ma,Guoqing Tang,Xuewei Li,Shunhua Zhang,Mailin Gan,Peiwen Zhang,Li Zhu,Yanzhi Jiang,Qiang Li,Jinyong Wang,Xue Zhao,Yan Xu

doi:10.3390/ijms19020501

Abstract

Intramuscular fat (IMF) content and composition are considered crucial indicators of porcine meat quality. However, the molecular mechanism of porcine IMF development is still mostly unclear. Recently, new evidence suggested that microRNA (miRNAs) play important roles in porcine intramuscular adipogenesis. Previously, microRNA-125a-5p (miR-125a-5p) was identified as an important regulator of adipogenesis. In the present study, we found that the expression of miR-125a-5p is dynamically regulated during porcine intramuscular preadipocytes differentiation and that its expression levels in different porcine muscle tissues were negatively involved with IMF content. To investigate the potential function role of miR-125a-5p in IMF development, porcine intramuscular preadipocytes were collected and transfected with miR-125a-5p mimics, inhibitors, or a negative control (NC), respectively. The results showed that overexpression of miR-125a-5p promoted proliferation and inhibited differentiation of porcine intramuscular preadipocytes while inhibition of miR-125a-5p had the opposite effects. Furthermore, a luciferase reporter assay demonstrated that porcine kruppel like factor 3 (KLF13) is a target gene of miR-125a-5p during porcine intramuscular preadipocytes differentiation. Interestingly, porcine ELOVL fatty acid elongase 6 (ELOVL6), a regulator of fatty acid composition, was also identified as a target gene of miR-125a-5p during porcine intramuscular adipogenesis. Further studies show that miR-125a-5p overexpression reduced total saturated fatty acids (SFA) content and monounsaturated fatty acids (MUFA)/SFA ratios while having no significant impact on polyunsaturated fatty acids (PUFA)/SFA and n-6/n-3 ratios. Taken together, our results identified that miR-125a-5p may be a novel regulator of porcine intramuscular adipogenesis and the fatty acid composition of porcine IMF.

Highlights

Pork production is a still growing industry on the international market [1]
We found that miR-125a-5p was expressed at higher levels in psoas major muscle (PMM) than the longissimus dorsi muscle (LDM) (Figure 1A), of which PMM has a higher percentage of Intramuscular fat (IMF) than LDM [21,22] (Figure 1B)
The results show that the IMF content of tongue muscle (TON) and obliquus externus abdominis (OEA) is significantly greater than other muscles including gastrocnemius muscle (GAM), masseter (MAS), and peroneal longus (PEL) (Figure 1C)

Summary

Introduction

Pork production is a still growing industry on the international market [1]. Intramuscular fat (IMF) content and composition such as fatty acid are important meat quality characteristics, which play important roles in the quality of meat including muscle color, tenderness, water-holding capacity, juiciness and flavor of cooked meat, but are closely associated with human health [4,5,6,7]. The quality of porcine meat is supposed to increase with higher IMF. Decreasing dietary saturated fatty acids (SFA), increasing monounsaturated (MUFA) fatty acids, or reducing the polyunsaturated (PUFA) n-6/n-3 fatty acid ratio in meat may reduce the risk of cardiovascular disease and improve human health [8,9,10]. The molecular mechanism regulating lipid accumulation and fatty acid composition in IMF among pork products remain poorly understood

Methods

Results

Conclusion