Cell biological study of the RANDAM-2 high positive cells and RANDAM-2 low/negative cells in mouse central nervous system.

RANDAM-2是一种在小鼠神经发生期间在兴奋性神经元细胞谱系上组成性表达的I型跨膜抗原，在胚胎第8.5天（E8.5）和E10.5之间显示出最高表达水平。由于该时期与神经干细胞（NSC）的增殖阶段完全重叠，因此可以想象RANDAM-2参与增殖和/或导致的神经分化。在本文中，我们表明，神经干细胞和NPC可以分离为RANDAM-2^<高+>和RANDAM-2^<低+/->细胞，分别通过阳性选择与RANDAM-2特异性的单克隆抗体。RANDAM-2^<high+>细胞具有高度的自我更新能力和向神经细胞多向分化的潜能。相反，几乎所有的RANDAM-2^<low+/->细胞不仅表现出极低的自我更新能力，而且表现出仅限于神经元的分化能力。这两个细胞群体在与神经分化相关的分子的表达水平方面也彼此不同。这些发现表明，RANDAM-2可以被认为是一个有用的标记物，用于分离的神经干细胞，并表明其高表达参与保留神经细胞的先天属性作为神经干细胞。

RANDAM-2, a type-I transmembrane antigen constitutively expressed on the excitatory neuronal cell lineage during mouse neurogenesis, shows the highest expression level between embryonic day 8.5 (E8.5) and E10.5. As the period well overlaps with the proliferating stages of neural stem cells (NSCs), it is conceivable that RANDAM-2 is involved in the proliferation and/or the resulting neural differentiation. In this paper, we show that NSCs and NPCs can be isolated as RANDAM-2^<high+> and RANDAM-2^<low+/-> cells, respectively, by positive selection with a monoclonal antibody specific to RANDAM-2. The isolated RANDAM-2^<high+> cells had the characteristics as the highly self-renewal capability and potential for multilineage differentiation into neural cells. In contrast, almost all of the RANDAM-2^<low+/-> cells exhibited not only the extremely low self-renewability but the differentiation capability restricted to neurons. These two cell populations also differed from each other in terms of the expression level of molecules associated with neural differentiation. These findings demonstrate that RANDAM-2 can be regarded as a useful marker for isolation of the NSCs, and suggest that its high expression takes part in the retention of the neural cells within the innate properties as NSCs.