GDNF family receptor alpha1 phenotype of spermatogonial stem cells in immature mouse testes
GDNF family receptor alpha1 phenotype of spermatogonial stem cells in immature mouse testes
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DOI：
10.1095/biolreprod.105.043810
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发表时间：
2005-11-01
影响因子：
3.6
通讯作者：
Schlatt, S
中科院分区：
文献类型：
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作者：
Buageaw, A;Sukhwani, M;Schlatt, S
精原干细胞（spermatogonialstemcells，SSCs）是精子发生所必需的成体组织干细胞，在自我更新和分化之间保持平衡，以满足睾丸的生物学需求。精原干细胞的发育动力学在一定程度上受干细胞龛中的因子控制，干细胞龛位于支持细胞之间的生精小管的基底膜上。支持细胞产生胶质细胞源性神经营养因子（GDNF），GDNF表达的破坏导致生精缺陷和不育。GDNF通过包括GDNF家族受体α 1（GFRA 1）的受体复合物发出信号，GFRA 1被认为由SSC表达。然而，GFRA 1在SSCs上的表达尚未通过体内功能测定来证实，体内功能测定是唯一允许确定性鉴定SSCs的方法。因此，我们使用磁激活细胞分选法基于GFRA 1表达对小鼠幼仔睾丸细胞进行分级。通过免疫细胞化学表征GFRA 1的分选和耗尽的级分的生殖细胞标志物，并通过生殖细胞移植表征其干细胞活性。GFRA 1阳性细胞组分与SSC的其他标志物（包括ITGA 6和CD9）共洗脱，并且显著耗尽了KIT阳性细胞。移植结果证实，SSC的亚群表达GFRA 1，但也证实干细胞库在GFRA 1表达水平方面是异质的。有趣的是，POU5F1阳性细胞在GFRA 1选择的部分中富集了近15倍，这可能表明干细胞库中发育潜力的异质性。
Spermatogonial stem cells (SSCs) are essential for spermatogenesis, and these adult tissue stem cells balance self-renewal and differentiation to meet the biological demand of the testis. The developmental dynamics of SSCs are controlled, in part, by factors in the stem cell niche, which is located on the basement membrane of seminiferous tubules situated among Sertoli cells. Sertoli cells produce glial cell line-derived neurotrophic factor (GDNF), and disruption of GDNF expression results in spermatogenic defects and infertility. The GDNF signals through a receptor complex that includes GDNF family receptor alpha 1 (GFRA1), which is thought to be expressed by SSCs. However, expression of GFRA1 on SSCs has not been confirmed by in vivo functional assay, which is the only method that allows definitive identification of SSCs. Therefore, we fractionated mouse pup testis cells based on GFRA1 expression using magnetic activated cell sorting. The sorted and depleted fractions of GFRA1 were characterized for germ cell markers by immunocytochemistry and for stem cell activity by germ cell transplantation. The GFRA1-positive cell fraction coeluted with other markers of SSCs, including ITGA6 and CD9, and was significantly depleted of KIT-positive cells. The transplantation results confirmed that a subpopulation of SSCs expresses GFRA1, but also that the stem cell pool is heterogeneous with respect to the level of GFRA1 expression. Interestingly, POU5F1-positive cells were enriched nearly 15-fold in the GFRA1-selected fraction, possibly suggesting heterogeneity of developmental potential within the stem cell pool.