MicroRNA-432 targeting <i>E2F3</i> and <i>P55PIK</i> inhibits myogenesis through PI3K/AKT/mTOR signaling pathway

Skeletal muscle is the dominant executant in locomotion and regulator in energy metabolism. Embryonic myogenesis and postnatal muscle growth are controlled by a cascade of transcription factors and epigenetic regulatory mechanisms. MicroRNAs (miRNAs), a family of non-coding RNA of 22 nucleotides in length, post-transcriptionally regulates expression of mRNA by pairing the seed sequence to 3′ UTR of target mRNA. Increasing evidence has demonstrated that miRNAs are important regulators in diverse myogenic processes. The profiling of miRNA expression revealed that miR-432 is more enriched in the <i>longissimus dorsi</i> of 35-day-old piglets than that of adult pigs. Our gain of function study showed that miR-432 can negatively regulate both myoblast proliferation and differentiation. Mechanically, we found that miR-432 is able to down-regulate E2F transcription factor 3 (E2F3) to inactivate the expression of cell cycle and myogenic genes. We also identified that phosphatidylinositol 3-kinase regulatory subunit (P55PIK) is another target gene of miR-432 in muscle cells. downregulation of P55PIK by miR-432 leads to inhibition of P55PIK-mediated PI3K/AKT/mTOR signaling pathway during differentiation. The blocking effect of miR-432 on this pathway can be rescued by insulin treatment. Taken together, our findings identified microRNA-432 as a potent inhibitor of myogenesis which functions by targeting E2F3 and P55PIK in muscle cells.

骨骼肌是运动的主要执行单元，亦是能量代谢的关键调控因子。胚胎期肌发生与出生后肌肉生长受一系列转录因子级联反应及表观遗传调控机制共同控制。微小RNA（MicroRNAs，miRNAs）是一类长度为22个核苷酸的非编码RNA家族，可通过其种子序列与靶mRNA的3'非翻译区（3' UTR）结合，在转录后水平调控mRNA的表达。越来越多的研究证据表明，miRNAs在多种肌发生过程中发挥重要调控作用。miRNA表达谱分析显示，相较于成年猪，miR-432在35日龄仔猪的背最长肌（longissimus dorsi）中表达更为富集。本研究的功能获得性实验结果表明，miR-432可负向调控成肌细胞的增殖与分化。从机制层面来看，miR-432能够下调E2F转录因子3（E2F transcription factor 3，E2F3）的表达，进而抑制细胞周期相关基因及肌源性基因的转录。本研究同时证实，磷脂酰肌醇3-激酶调节亚基（phosphatidylinositol 3-kinase regulatory subunit，P55PIK）是miR-432在肌肉细胞中的另一靶基因。miR-432通过下调P55PIK的表达，可在细胞分化过程中抑制P55PIK介导的PI3K/AKT/mTOR信号通路。胰岛素处理能够挽救miR-432对该通路的阻断效应。综上，本研究证实微小RNA-432是一种强效的肌发生抑制剂，其通过在肌肉细胞中靶向E2F3与P55PIK发挥调控功能。

搜集汇总

背景与挑战

背景概述

该数据集为一项关于microRNA-432在骨骼肌发育中作用的研究数据，发布于2017年。研究通过实验验证miR-432靶向E2F3和P55PIK基因，抑制肌细胞增殖和分化，并揭示其通过PI3K/AKT/mTOR信号通路影响肌生成过程。数据集补充了相关RNA生物学研究，涵盖生物物理学、生物化学和分子生物学等多个学科领域。