Myostatin regulates fatty acid desaturation and fat deposition through MEF2C/miR222/SCD5 cascade in pigs

Hongyan Ren,Xingliang Qin,Cheng Cheng,Jie Yao,Liping Zhang,Xinglei Li,Gangzhi Cai,Wei Xiao,Xinmin Zheng,Wenjun Hua,Zhe Zhu,Zaidong Hua,Hongwei Xiao,Yanzhen Bi,Hao Chen,Chong Qian,Jiali Dai

doi:10.1038/s42003-020-01348-8

Abstract

Myostatin (MSTN), associated with the “double muscling” phenotype, affects muscle growth and fat deposition in animals, whereas how MSTN affects adipogenesis remains to be discovered. Here we show that MSTN can act through the MEF2C/miR222/SCD5 cascade to regulate fatty acid metabolism. We generated MSTN-knockout (KO) cloned Meishan pigs, which exhibits typical double muscling trait. We then sequenced transcriptome of subcutaneous fat tissues of wild-type (WT) and MSTN-KO pigs, and intersected the differentially expressed mRNAs and miRNAs to predict that stearoyl-CoA desaturase 5 (SCD5) is targeted by miR222. Transcription factor binding prediction showed that myogenic transcription factor 2C (MEF2C) potentially binds to the miR222 promoter. We hypothesized that MSTN-KO upregulates MEF2C and consequently increases the miR222 expression, which in turn targets SCD5 to suppress its translation. Biochemical, molecular and cellular experiments verified the existence of the cascade. This novel molecular pathway sheds light on new targets for genetic improvements in pigs.

Highlights

Myostatin (MSTN), associated with the “double muscling” phenotype, affects muscle growth and fat deposition in animals, whereas how MSTN affects adipogenesis remains to be discovered
Targeted genomic engineering can be accomplished with gene editors like CRISPR/Cas[9] via error-prone non-homologous end joining (NHEJ) repair pathway, but NHEJ-mediated gene editing is not predictable and tends to introduce heterogeneous mutations
homology-mediated recombination (HDR) is a promising route for precise gene editing because it can actualize high-fidelity DNA repair, in contrast to the error-prone NHEJ repair pathway[9]

Summary

Introduction

Myostatin (MSTN), associated with the “double muscling” phenotype, affects muscle growth and fat deposition in animals, whereas how MSTN affects adipogenesis remains to be discovered. Functional blockade of MSTN results in the double muscling trait in animals, which features overgrown skeletal muscle and reduced fat mass Owning to this advantage, MSTN has been a prime genetic target for the development of high-leanness animal cultivars in livestock, poultry and fishery industries, via multifaceted approaches like ectopically expressed MSTN propeptide, dominant negative competitor, RNA interference, gene targeting and gene editing[1,2,3,4]. We first devised an improved gene targeting strategy relying on dual fluorescence-assisted selection (DUFAS) to couple CRISPR/Cas[9] with homology-mediated recombination (HDR) for two purposes: 1, to assure the precise mutation of MSTN, and 2, to enrich the on-target events with high efficiency Using this new strategy, we generated cloned MSTN-KO Meishan pigs, which exhibited a typical double muscled phenotype. We experimentally validated the existence of a novel cascade via which MSTN regulates fatty acid metabolism and fat deposition in pigs

Objectives

Methods

Results

Conclusion