利用miRNAs诱导小鼠iPS细胞形成精原干细胞样细胞

将iPS细胞（iPSCs）诱导成生殖细胞具有重要的理论和应用价值。近来人们已经能够将小鼠的iPSCs或ESCs诱导形成具有功能的卵母细胞和精子细胞；但是所形成的精子细胞在形态和功能上与成熟的精子尚有较大差异。申请人团队能够将小鼠的精原干细胞（SSCs）在体外长期大量扩增并诱导其启动减数分裂；我们还成功地将小鼠iPSCs诱导成具有有限增殖能力的SSC-like细胞（SSCLCs）；系统地检测了小分子RNAs在生精细胞中的表达，发现miR-202在SSCs中高度表达并维持SSCs的自我更新。在本申请中，我们将首先探索是否可以通过表达外源miR-202和/或其他miRNAs来诱导小鼠iPSCs形成具有长期自我更新能力的SSCLCs，并对SSCLCs的功能进行严格鉴定；然后我们将尝试利用人工合成的miRNA类似物来实现该诱导过程。这些工作的完成将为我们最终在体外获得功能完全正常的精子奠定基础。

The induction of germ cells from iPS cells (iPSCs) is highly valuable both theoretically and practically. Researchers have been able to induce mouse iPSCs or ESCs into functional oocytes and spermatids. However, the induced spermatids are still quite different from mature sperms in terms of both morphology and function. My team has long been engaged in the in vitro propagation and differentiation of mouse spermatogonial stem cells (SSCs), and is able to amplify SSCs in large quantities for long terms. We have also induced mouse iPSCs into SSC-like cells (SSCLCs). We have profiled the expression of small RNAs in mouse spermatogenic cells and found that miR-202 is specifically expressed in SSCs and plays an essential role in maintaining SSC self-renewal. In the present application, we will first explore whether we are able to induce mouse iPSCs into SSCLCs that are highly self-renewable by overexpressing miR-202 and/or other miRNAs, and study the underlining mechanism. We will then try to finish the same induction using synthetic miRNA mimics. The accomplishment of this work will contribute to establishing a solid foundation whereby fully functional sperms can be derived.