Effects and Molecular Mechanism of Single-Nucleotide Polymorphisms of MEG3 on Porcine Skeletal Muscle Development.

Rui Yang,Guanhong Lu,Jie Song,Tianqi Feng,Xiaotong Sun,Yinuo Liu,Jilun Meng,Chunli Wang,Siyao Wang,Yunyun Cheng,Linlin Hao

doi:10.3389/fgene.2021.607910

Abstract

Maternally expressed gene 3 (MEG3) is a long non-coding RNA that is a crucial regulator of skeletal muscle development. Some single-nucleotide polymorphism (SNP) mutants in MEG3 had strong associations with meat quality traits. Nevertheless, the function and mechanism of MEG3 mutants on porcine skeletal muscle development have not yet been well-demonstrated. In this study, eight SNPs were identified in MEG3 of fat- and lean-type pig breeds. Four of these SNPs (g.3087C > T, g.3108C > T, g.3398C > T, and g.3971A > C) were significantly associated with meat quality and consisted of the CCCA haplotype for fat-type pigs and the TTCC haplotype for lean-type pigs. Quantitative real-time PCR results showed that the expression of MEG3-TTCC was higher than that of MEG3-CCCA in transcription level (P < 0.01). The stability assay showed that the lncRNA stability of MEG3-TTCC was lower than that of MEG3-CCCA (P < 0.05). Furthermore, the results of qRT-PCR, Western blot, and Cell Counting Kit-8 assays demonstrated that the overexpression of MEG3-TTCC more significantly inhibited the proliferation of porcine skeletal muscle satellite cells (SCs) than that of MEG3-CCCA (P < 0.05). Moreover, the overexpression of MEG3-TTCC more significantly promoted the differentiation of SCs than that of MEG3-CCCA (P < 0.05). The Western blot assay suggested that the overexpression of MEG3-TTCC and MEG3-CCCA inhibited the proliferation of SCs by inhibiting PI3K/AKT and MAPK/ERK1/2 signaling pathways. The overexpression of the two haplotypes also promoted the differentiation of SCs by activating the JAK2/STAT3 signaling pathway in different degrees. These data are valuable for further studies on understanding the crucial role of lncRNAs in skeletal muscle development.

Highlights

Skeletal muscle is the most abundant muscle in mammals (Ge et al, 2019; Han et al, 2019)
The results suggested that the four single-nucleotide polymorphism (SNP) showed linkage inheritance and formed four haplotypes
The frequency of haplotype TTCC was higher in lean-type pigs (71.4%), indicating that TTCC was the advantageous haplotype of lean-type pigs (P < 0.001) (Table 3)

Summary

Introduction

Skeletal muscle is the most abundant muscle in mammals (Ge et al, 2019; Han et al, 2019). Skeletal muscle satellite cells (SCs) are located between the myofiber membrane and basal lamina membrane of muscle fibers (Koning et al, 2012; Guo et al, 2018). SCs are terminally differentiated into multinucleated myotubes and myofibers, which are essential for postnatal growth and regeneration of skeletal muscles (Felicioni et al, 2020). European commercial pig breeds are typically lean breeds with representative lean genotype and are widely used as the experimental objects (Gil et al, 2008; Wu et al, 2013; Yang et al, 2014), such as Landrace pigs, Duroc pigs, Yorkshire pigs, and Pietrain pigs have faster growth rate and higher lean meat content than BaMa pig breeds (Liu et al, 2015; Li et al, 2016). According to the Chinese Livestock or Poultry Genetic Resource-Pigs (National Committee for Livestock or Poultry Genetic Resource, 2011), the lean meat content (%) of European commercial pig breeds is higher than that of BaMa pig breed (P < 0.05)

Objectives

Methods

Results

Conclusion