Luo Wen, Li Guihuan, Yi Zhenhua, Nie Qinghua, Zhang Xiquan
Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou 510642, Guangdong Province, China.
Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, and Key Lab of Chicken Genetics, Breeding and Reproduction, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, Guangdong Province, China.
Sci Rep. 2016 Jun 10;6:27904. doi: 10.1038/srep27904.
miR-17 family microRNAs (miRNAs) are crucial for embryo development, however, their role in muscle development is still unclear. miR-20a-5p and miR-20b-5p belong to the miR-17 family and are transcribed from the miR-1792 and miR-106a363 clusters respectively. In this study, we found that miR-20a-5p and miR-20b-5p promoted myoblast differentiation and repressed myoblast proliferation by directly binding the 3' UTR of E2F transcription factor 1 (E2F1) mRNA. E2F1 is an important transcriptional factor for organism's normal development. Overexpression of E2F1 in myoblasts promoted myoblast proliferation and inhibited myoblast differentiation. Conversely, E2F1 inhibition induced myoblast differentiation and repressed myoblast proliferation. Moreover, E2F1 can bind directly to promoters of the miR-1792 and miR-106a363 clusters and activate their transcription, and E2F1 protein expression is correlated with the expression of pri-miR-1792 and pri-miR-106a363 during myoblast differentiation. These results suggested an auto-regulatory feedback loop between E2F1 and miR-20a-5p/20b-5p, and indicated that miR-20a-5p, miR-20b-5p and E2F1 are involved in myoblast proliferation and differentiation through the auto-regulation between E2F1 and miR-20a-5p/20b-5p. These findings provide new insight into the mechanism of muscle differentiation, and further shed light on the understanding of muscle development and muscle diseases.
微小RNA-17家族微小RNA（miRNA）对胚胎发育至关重要，然而，它们在肌肉发育中的作用仍不清楚。miR-20a-5p和miR-20b-5p属于微小RNA-17家族，分别从微小RNA-1792和微小RNA-106a363簇转录而来。在本研究中，我们发现miR-20a-5p和miR-20b-5p通过直接结合E2F转录因子1（E2F1）mRNA的3'非翻译区促进成肌细胞分化并抑制成肌细胞增殖。E2F1是生物体正常发育的重要转录因子。成肌细胞中E2F1的过表达促进成肌细胞增殖并抑制成肌细胞分化。相反，E2F1抑制诱导成肌细胞分化并抑制成肌细胞增殖。此外，E2F1可直接结合微小RNA-1792和微小RNA-106a363簇的启动子并激活它们的转录，并且在成肌细胞分化过程中E2F1蛋白表达与初级微小RNA-1792和初级微小RNA-106a363的表达相关。这些结果提示了E2F1与miR-20a-5p/20b-5p之间的自调控反馈环，并表明miR-20a-5p、miR-20b-5p和E2F1通过E2F1与miR-20a-5p/20b-5p之间的自调控参与成肌细胞增殖和分化。这些发现为肌肉分化机制提供了新的见解，并进一步有助于对肌肉发育和肌肉疾病的理解。
