韩春生研究组最新文章发现精原干细胞体外减数分裂的奥秘

　　

　不育症给个人、家庭和社会带来严重困扰。男性不育约占人类不育病例的50%，由多种遗传和表观遗传变异所致，主要表现为生殖细胞缺失以及减数分裂启动、完成和单倍体发育异常。长期以来由于缺少精原细胞干细胞的体外培养、基因修饰以及分化模型，人类对精子发生以及男性不育的机理研究进展缓慢。

　　近来，中国科学院动物研究所韩春生研究团队成功建立了在体外将小鼠精原干细胞诱导形成精母细胞的技术体系，发现视黄酸（RA）是这个体外系统的充分必要条件；在分化系统中添加外源RA同时进行精原干细胞和睾丸支持细胞（Sertoli Cells）的共培养，能够以约30%的效率获得正在进行减数分裂的细线期和偶线期精母细胞。他们还利用RNA测序技术发现了大量受RA调控的参与干细胞自我更新和分化的基因，并进一步利用该体外技术鉴定出了参与精原干细胞减数分裂的新基因。这些工作为实现体外诱导二倍体精原干细胞形成单倍体精子细胞的工作奠定了基础，并且为研究减数分裂的分子机理提供了理想的体外模型。这一工作以Retinoic Acid Is Sufficient for the in vitro Induction of Mouse Spermatocytes 为题目于6月23日在Stem Cell Reports 杂志线上发表。该研究得到了国家基础研究计划和国家自然科学基金的资助。

　　韩春生研究团队多年来一直集中进行精子发生和减数分裂的研究，是国内第一个报道建立小鼠精原干细胞体外长期培养、基因修饰和利用该技术体系获得转基因小鼠的实验室。他们还发现了FGF2和IGF1信号通路是小鼠精原干细胞体外增殖的必要因素；成功地将小鼠iPS细胞在体外以40%的效率诱导形成原始生殖细胞。这些成果曾发表在Cell Research （2012）22:773；Stem Cell Research （2013）12:517；Stem Cells and Development（2015）24:471 等期刊上。

 

　　小鼠精原干细胞（SSC）在RA和Sertoli Cell的作用下形成诱导分化型精原细胞（idSG）和正在进行减数分裂的诱导型精母细胞（iSC）

原文摘要：

Retinoic Acid Is Sufficient for the In Vitro Induction of Mouse Spermatocytes

Meiosis is the key step in gametogenesis. However, the mechanism of mammalian meiosis remains poorly understood due to the lack of an in vitro model. Here, we report that retinoic acid (RA) is sufficient for inducing leptotene/zygotene spermatocytes from cultured mouse spermatogonial stem cells. Multiple genes regulated by RA were identified by RNA sequencing. RA in combination with pup Sertoli cell co-culture resulted in a higher induction efficiency of 28%. Comparisons in the transcriptomic profiles of the induced spermatogenic cells and the isolated ones revealed the progressive induction of the germ cells. Using this model, we showed that Stra8, Agpat3, Fam57a, Wdr91, and Sox30 contributed to the proliferation and meiosis initiation differentially. In conclusion, we have efficiently generated spermatocytes using an RA/pup Sertoli cell-based in vitro model and provided proof-of-concept evidence for its application in identifying genes involved in mammalian meiosis.