Zhang Yi, Shen Bingqiao, Zhang Dandan, Wang Yuyao, Tang Zhimin, Ni Ni, Jin Xiaoliang, Luo Min, Sun Hao, Gu Ping
Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200011, China.
Oncotarget. 2017 May 9;8(19):31993-32008. doi: 10.18632/oncotarget.16669.
During development, tight regulation of the expansion of retinal progenitor cells (RPCs) and their differentiation into neuronal and glial cells is important for retinal formation and function. Our study demonstrated that microRNA (miR)-29a modulated the proliferation and differentiation of RPCs by suppressing RBM8A (one of the factors in the exon junction complex). Particularly, overexpression of miR-29a reduced RPC proliferation but accelerated RPC differentiation. By contrast, reduction of endogenous miR-29a elicited the opposite effects. Overexpression of miR-29a repressed the translation of Rbm8a, thus negatively regulating RPC proliferation and promoting the neuronal and glial differentiation of RPCs, and knockdown of endogenous Rbm8a phenocopied the observed effects of miR-29a overexpression. Furthermore, a luciferase reporter assay showed that miR-29a directly interacted with the Rbm8a mRNA 3'UTR, which indicated that Rbm8a is the direct target of miR-29a. To further verify the result, co-overexpression of the Rbm8a 3' UTR-wt (plasmids into which the Rbm8a 3' UTR sequence had been introduced) and miR-29a in RPCs rescued the phenotype associated with miR-29a overexpression, reversing the promotion of differentiation and inhibition of proliferation. These results show a novel mechanism by which miR-29a regulates the proliferation and differentiation of RPCs through Rbm8a.
在发育过程中，视网膜祖细胞（RPCs）扩增及其向神经元和神经胶质细胞分化的严格调控对于视网膜的形成和功能至关重要。我们的研究表明，微小RNA（miR）-29a通过抑制RBM8A（外显子连接复合体中的一个因子）来调节RPCs的增殖和分化。具体而言，miR-29a的过表达降低了RPCs的增殖，但加速了RPCs的分化。相反，内源性miR-29a的减少则产生相反的效果。miR-29a的过表达抑制了Rbm8a的翻译，从而负向调节RPCs的增殖并促进RPCs向神经元和神经胶质细胞的分化，而内源性Rbm8a的敲低模拟了miR-29a过表达所观察到的效果。此外，荧光素酶报告基因检测表明miR-29a直接与Rbm8a mRNA的3'UTR相互作用，这表明Rbm8a是miR-29a的直接靶标。为了进一步验证该结果，在RPCs中共过表达Rbm8a 3'UTR-wt（已引入Rbm8a 3'UTR序列的质粒）和miR-29a挽救了与miR-29a过表达相关的表型，逆转了分化促进和增殖抑制。这些结果揭示了一种新的机制，即miR-29a通过Rbm8a调节RPCs的增殖和分化。
