Spana E P, Kopczynski C, Goodman C S, Doe C Q
Howard Hughes Medical Institute, Department of Cell and Structural Biology, University of Illinois, Urbana 61801, USA.
Development. 1995 Nov;121(11):3489-94. doi: 10.1242/dev.121.11.3489.
The central nervous system (CNS) represents an excellent model system for examining how a multitude of unique cell fates are specified. We find that asymmetric localization of the numb protein autonomously controls a binary cell fate decision in the Drosophila CNS. The simplest lineage in the Drosophila CNS is that of the MP2 precursor: it divides unequally to generate the dMP2 and vMP2 neurons. Both are interneurons but project in different directions: dMP2 projects its axon posteriorly while vMP2 projects anteriorly. During MP2 mitosis, numb is localized into dMP2 and excluded from vMP2. Loss of numb transforms dMP2 into vMP2, whereas ectopic numb produces the opposite transformation of vMP2 into dMP2. Thus, numb is asymmetrically localized in the dividing MP2 and is necessary and sufficient to autonomously specify dMP2 neuronal identity.
中枢神经系统（CNS）是研究众多独特细胞命运如何被确定的极佳模型系统。我们发现麻木蛋白的不对称定位自主控制果蝇中枢神经系统中的二元细胞命运决定。果蝇中枢神经系统中最简单的谱系是MP2前体的谱系：它进行不均等分裂以产生dMP2和vMP2神经元。两者都是中间神经元，但投射方向不同：dMP2向后投射其轴突，而vMP2向前投射。在MP2有丝分裂期间，麻木定位于dMP2中并被排除在vMP2之外。麻木的缺失将dMP2转化为vMP2，而异位表达的麻木则产生相反的转化，即vMP2转化为dMP2。因此，麻木在分裂的MP2中不对称定位，并且对于自主确定dMP2神经元身份是必要且充分的。
