The spermatogonial stem cell (SSC) population in testis is small, and the lack of SSC markers has severely handicapped research on these cells. During our attempt to identify genes involved in SSC aging, we found that CD2 is expressed in cultured SSCs. Flow cytometric analysis and spermatogonial transplantation experiments showed that CD2 is expressed in SSCs from mature adult mouse testes. Cultured SSCs transfected with short hairpin RNAs (shRNAs) against CD2 proliferated poorly and showed an increased frequency of apoptosis. Moreover, functional analysis of transfected cells revealed impairment of SSC activity. Fluorescence activated cell sorting and spermatogonial transplantation experiments showed that CD2 is expressed not only in mouse but also in rat SSCs. The results indicate that CD2 is a novel SSC surface marker conserved between mouse and rat SSCs.

中文翻译：

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CD2 是小鼠和大鼠精原干细胞的表面标志物

睾丸中的精原干细胞 (SSC) 数量很少，SSC 标记物的缺乏严重阻碍了对这些细胞的研究。在我们尝试鉴定参与 SSC 衰老的基因期间，我们发现 CD2 在培养的 SSC 中表达。流式细胞术分析和精原细胞移植实验表明 CD2 在成熟成年小鼠睾丸的 SSC 中表达。用针对 CD2 的短发夹 RNA (shRNA) 转染的培养 SSC 增殖不佳，并显示出凋亡频率增加。此外，转染细胞的功能分析显示 SSC 活性受损。荧光激活细胞分选和精原细胞移植实验表明，CD2 不仅在小鼠中表达，还在大鼠 SSC 中表达。