Fondazione Pasteur Cenci Bolognetti, Department of Anatomical, Histological, Forensic and Orthopaedic Sciences - Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy.
PLoS One. 2013 Apr 22;8(4):e59431. doi: 10.1371/journal.pone.0059431. Print 2013.
In mammals, the biological activity of the stem/progenitor compartment sustains production of mature gametes through spermatogenesis. Spermatogonial stem cells and their progeny belong to the class of undifferentiated spermatogonia, a germ cell population found on the basal membrane of the seminiferous tubules. A large body of evidence has demonstrated that glial cell line-derived neurotrophic factor (GDNF), a Sertoli-derived factor, is essential for in vivo and in vitro stem cell self-renewal. However, the mechanisms underlying this activity are not completely understood. In this study, we show that GDNF induces dose-dependent directional migration of freshly selected undifferentiated spermatogonia, as well as germline stem cells in culture, using a Boyden chamber assay. GDNF-induced migration is dependent on the expression of the GDNF co-receptor GFRA1, as shown by migration assays performed on parental and GFRA1-transduced GC-1 spermatogonial cell lines. We found that the actin regulatory protein vasodilator-stimulated phosphoprotein (VASP) is specifically expressed in undifferentiated spermatogonia. VASP belongs to the ENA/VASP family of proteins implicated in actin-dependent processes, such as fibroblast migration, axon guidance, and cell adhesion. In intact seminiferous tubules and germline stem cell cultures, GDNF treatment up-regulates VASP in a dose-dependent fashion. These data identify a novel role for the niche-derived factor GDNF, and they suggest that GDNF may impinge on the stem/progenitor compartment, affecting the actin cytoskeleton and cell migration.
在哺乳动物中，干细胞/祖细胞区室的生物学活性通过精子发生维持成熟配子的产生。精原干细胞及其后代属于未分化精原细胞类，这是一种存在于曲细精管基底膜上的生殖细胞群体。大量证据表明，胶质细胞系衍生的神经营养因子（GDNF）是一种由支持细胞分泌的因子，对体内和体外干细胞自我更新是必需的。然而，这种活性的机制尚不完全清楚。在这项研究中，我们使用 Boyden 室测定法表明，GDNF 诱导新鲜选择的未分化精原细胞以及培养中的生殖干细胞的剂量依赖性定向迁移。通过在亲本和 GFRA1 转导的 GC-1 精原细胞系上进行迁移测定，我们发现 GDNF 诱导的迁移依赖于 GDNF 共同受体 GFRA1 的表达。我们发现，血管舒张刺激磷蛋白（VASP）这种肌动蛋白调节蛋白特异性表达于未分化的精原细胞中。VASP 属于 ENA/VASP 蛋白家族，该家族蛋白参与肌动蛋白依赖的过程，如成纤维细胞迁移、轴突导向和细胞黏附。在完整的曲细精管和生殖干细胞培养物中，GDNF 处理以剂量依赖的方式上调 VASP。这些数据确定了来源因子 GDNF 的新作用，并且它们表明 GDNF 可能影响干细胞/祖细胞区室，影响肌动蛋白细胞骨架和细胞迁移。
