Klämbt C
Institut für Entwicklungsbiologie, Köln, Germany.
Development. 1993 Jan;117(1):163-76. doi: 10.1242/dev.117.1.163.
Glial-neuronal cell interactions at the ventral midline are necessary for the proper elaboration of commissures in the embryonic CNS of Drosophila. In particular, migrating midline glial cells are required for the separation of segmental commissures. During this process the glial cells recognize specific neuronal cells at the midline, they migrate posteriorly along their cell processes and thereby separate the segmental commissures. The gene pointed (pnt) is required for this glial-neuronal cell interaction, as loss of function mutations lead to a change in the migration behavior of the midline glial cells. As a consequence, anterior and posterior commissures do not become separated and appear fused. Molecular analysis of pointed has revealed two differently spliced types of transcripts, which are encoded in a region extending over 55 kb of genomic sequence. In the CNS both transcript classes are expressed in cells of the midline, including the midline glial cells. Sequence analysis of cDNA clones corresponding to both transcript types reveals two different pointed proteins which share an ETS domain common to a number of transcription factors related to the vertebrate ets oncogene. Furthermore, one pointed protein form contains an additional domain of homology of approx. 80 amino acids in length, which is shared by only a subset of the ETS protein family.
在果蝇胚胎中枢神经系统中，腹侧中线处的神经胶质细胞与神经元细胞的相互作用对于连合纤维的正常形成是必要的。特别是，迁移的中线神经胶质细胞对于节段连合纤维的分离是必需的。在这个过程中，神经胶质细胞在中线识别特定的神经元细胞，它们沿着细胞突起向后迁移，从而分离节段连合纤维。基因pointed（pnt）对于这种神经胶质细胞与神经元细胞的相互作用是必需的，因为功能丧失突变会导致中线神经胶质细胞迁移行为的改变。结果，前后连合纤维没有分离而是出现融合。对pointed的分子分析揭示了两种不同剪接类型的转录本，它们编码在一个跨越55kb基因组序列的区域。在中枢神经系统中，这两种转录本类型都在中线细胞中表达，包括中线神经胶质细胞。对与两种转录本类型相对应的cDNA克隆的序列分析揭示了两种不同的pointed蛋白，它们共享一个与脊椎动物ets癌基因相关的许多转录因子共有的ETS结构域。此外，一种pointed蛋白形式包含一个额外的约80个氨基酸长度的同源结构域，只有ETS蛋白家族的一个子集共享该结构域。
