Cesetti Tiziana, Obernier Kirsten, Bengtson C Peter, Fila Tatiana, Mandl Claudia, Hölzl-Wenig Gabriele, Wörner Kerstin, Eckstein Volker, Ciccolini Francesca
Department of Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg, Heidelberg, Germany.
Stem Cells. 2009 Jun;27(6):1443-54. doi: 10.1002/stem.74.
In the adult subventricular zone (SVZ), astroglial stem cells generate transit-amplifying precursors (TAPs). Both stem cells and TAPs form clones in response to epidermal growth factor (EGF). However, in vivo, in the absence of sustained EGF receptor (EGFR) activation, TAPs divide a few times before differentiating into neuroblasts. The lack of suitable markers has hampered the analysis of stem cell lineage progression and associated functional changes in the neonatal germinal epithelium. Here we purified neuroblasts and clone-forming precursors from the neonatal SVZ using expression levels of EGFR and polysialylated neural cell adhesion molecule (PSANCAM). As in the adult SVZ, most neonatal clone-forming precursors did not express the neuroglia proteoglycan 2 (NG2) but displayed characteristics of TAPs, and only a subset exhibited antigenic characteristics of astroglial stem cells. Both precursors and neuroblasts were PSANCAM(+); however, neuroblasts also expressed doublecortin and functional voltage-dependent Ca(2+) channels. Neuroblasts and precursors had distinct outwardly rectifying K(+) current densities and passive membrane properties, particularly in precursors contacting each other, because of the contribution of gap junction coupling. Confirming the hypothesis that most are TAPs, cell tracing in brain slices revealed that within 2 days the majority of EGFR(+) cells had exited the cell cycle and differentiated into a progenitor displaying intermediate antigenic and functional properties between TAPs and neuroblasts. Thus, distinct functional and antigenic properties mark stem cell lineage progression in the neonatal SVZ.
在成体脑室下区（SVZ），星形胶质干细胞产生过渡放大前体细胞（TAPs）。干细胞和TAPs均可对表皮生长因子（EGF）产生反应而形成克隆。然而，在体内，在缺乏持续的表皮生长因子受体（EGFR）激活的情况下，TAPs在分化为神经母细胞之前仅分裂几次。由于缺乏合适的标志物，阻碍了对新生生发上皮中干细胞谱系进展及相关功能变化的分析。在此，我们利用EGFR和多唾液酸神经细胞黏附分子（PSANCAM）的表达水平，从新生SVZ中纯化出神经母细胞和克隆形成前体细胞。与成体SVZ一样，大多数新生克隆形成前体细胞不表达神经胶质蛋白聚糖2（NG2），而是表现出TAPs的特征，只有一小部分表现出星形胶质干细胞的抗原特性。前体细胞和神经母细胞均为PSANCAM阳性；然而，神经母细胞还表达双皮质素和功能性电压依赖性Ca2+通道。神经母细胞和前体细胞具有不同的外向整流钾电流密度和被动膜特性，尤其是在相互接触的前体细胞中，这是由于缝隙连接耦合的作用。脑片细胞追踪证实了大多数细胞为TAPs这一假设，即在2天内，大多数EGFR阳性细胞退出细胞周期，分化为一种祖细胞，其抗原和功能特性介于TAPs和神经母细胞之间。因此，独特的功能和抗原特性标志着新生SVZ中干细胞谱系的进展。
