Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
AMED-CREST, Tokyo, Japan.
Biol Reprod. 2023 Apr 11;108(4):682-693. doi: 10.1093/biolre/ioad006.
Characterization of spermatogonial stem cells (SSCs) has been hampered by their low frequency and lack of features that distinguish them from committed spermatogonia. Few conserved SSC markers have been discovered. To identify a new SSC marker, we evaluated SIRPA expression in mouse and rat SSCs. SIRPA was expressed in a small population of undifferentiated spermatogonia. SIRPA, and its ligand CD47 were expressed in cultured SSCs. Expression of both SIRPA and CD47 was upregulated by supplementation of GDNF and FGF2, which promoted SSC self-renewal. Sirpa depletion by short hairpin RNA impaired the proliferation of cultured SSCs, and these cells showed decreased MAP2K1 activation and PTPN11 phosphorylation. Immunoprecipitation experiments showed that SIRPA associates with PTPN11. Ptpn11 depletion impaired SSC activity in a manner similar to Sirpa depletion. SIRPA was expressed in undifferentiated spermatogonia in rat and monkey testes. Xenogenic transplantation experiments demonstrated that SIRPA is expressed in rat SSCs. These results suggest that SIRPA is a conserved SSC marker that promotes SSC self-renewal division by activating the MAP2K1 pathway via PTPN11.
精原干细胞（SSC）的特征一直受到其低频率和缺乏与定向精原细胞区分的特征的阻碍。很少发现保守的 SSC 标志物。为了鉴定新的 SSC 标志物，我们评估了 SIRPA 在小鼠和大鼠 SSCs 中的表达。SIRPA 在未分化的精原细胞的一小部分中表达。SIRPA 及其配体 CD47 在培养的 SSCs 中表达。补充 GDNF 和 FGF2 可上调 SIRPA 和 CD47 的表达，促进 SSC 自我更新。短发夹 RNA 敲低 SIRPA 会损害培养的 SSCs 的增殖，这些细胞显示出 MAP2K1 激活和 PTPN11 磷酸化减少。免疫沉淀实验表明 SIRPA 与 PTPN11 相关。Ptpn11 敲低以类似于 Sirpa 敲低的方式损害 SSC 活性。SIRPA 在大鼠和猴子睾丸的未分化精原细胞中表达。异种移植实验表明 SIRPA 存在于大鼠 SSCs 中。这些结果表明 SIRPA 是一种保守的 SSC 标志物，通过 PTPN11 激活 MAP2K1 途径促进 SSC 自我更新分裂。
