Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Agency for Medical Research and Development-Core Research for Evolutional Science and Technology, Tokyo, Japan.
Biol Reprod. 2020 Feb 12;102(1):220-232. doi: 10.1093/biolre/ioz156.
Spermatogonial stem cells (SSCs) undergo continuous self-renewal division in response to self-renewal factors. The present study identified ephrin type-A receptor 2 (EPHA2) on mouse SSCs and showed that supplementation of glial cell-derived neurotrophic factor (GDNF) and fibroblast growth factor 2 (FGF2), which are both SSC self-renewal factors, induced EPHA2 expression in cultured SSCs. Spermatogonial transplantation combined with magnetic-activated cell sorting or fluorescence-activated cell sorting also revealed that EPHA2 was expressed in SSCs. Additionally, ret proto-oncogene (RET) phosphorylation levels decreased following the knockdown (KD) of Epha2 expression via short hairpin ribonucleic acid (RNA). Although the present immunoprecipitation experiments did not reveal an association between RET with EPHA2, RET interacted with FGFR2. The Epha2 KD decreased the proliferation of cultured SSCs and inhibited the binding of cultured SSCs to laminin-coated plates. The Epha2 KD also significantly reduced the colonization of testis cells by spermatogonial transplantation. EPHA2 was also expressed in human GDNF family receptor alpha 1-positive spermatogonia. The present results indicate that SSCs express EPHA2 and suggest that it is a critical modifier of self-renewal signals in SSCs.
精原干细胞（SSCs）在自我更新因子的作用下持续进行自我更新分裂。本研究鉴定了小鼠 SSCs 上的 Ephrin 型-A 受体 2（EPHA2），并表明胶质细胞衍生的神经营养因子（GDNF）和纤维母细胞生长因子 2（FGF2）这两种 SSC 自我更新因子的补充可诱导培养的 SSCs 中 EPHA2 的表达。精原干细胞移植结合磁激活细胞分选或荧光激活细胞分选也表明 EPHA2 在 SSCs 中表达。此外，通过短发夹 RNA（shRNA）敲低 Epha2 表达后，原癌基因 ret（RET）磷酸化水平降低。虽然本免疫沉淀实验未显示 RET 与 EPHA2 之间存在关联，但 RET 与 FGFR2 相互作用。Epha2 KD 降低了培养的 SSCs 的增殖，并抑制了培养的 SSCs 与层粘连蛋白包被板的结合。Epha2 KD 还显著降低了精原干细胞移植的睾丸细胞定植。EPHA2 也在人 GDNF 家族受体 alpha 1 阳性精原细胞中表达。本研究结果表明 SSCs 表达 EPHA2，并提示其是 SSCs 自我更新信号的关键修饰因子。
