Pallavi S K, Shashidhara L S
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, India 500 007.
Development. 2003 Oct;130(20):4931-41. doi: 10.1242/dev.00719. Epub 2003 Aug 20.
All imaginal discs in Drosophila are made up of a layer of columnar epithelium or the disc proper and a layer of squamous epithelium called the peripodial membrane. Although the developmental and molecular events in columnar epithelium or the disc proper are well understood, the peripodial membrane has gained attention only recently. Using the technique of lineage tracing, we show that peripodial and disc proper cells arise from a common set of precursors cells in the embryo, and that these cells diverge in the early larval stages. However, peripodial and disc proper cells maintain a spatial relationship even after the separation of their lineages. The peripodial membrane plays a significant role during the regional subdivision of the wing disc into presumptive wing, notum and hinge. The Egfr/Ras pathway mediates this function of the peripodial membrane. These results on signaling between squamous and columnar epithelia are particularly significant in the context of in vitro studies using human cell lines that suggest a role for the Egfr/Ras pathway in metastasis and tumour progression.
果蝇中的所有成虫盘均由一层柱状上皮细胞（即盘本身）和一层称为围食膜的鳞状上皮细胞组成。尽管柱状上皮细胞或盘本身中的发育和分子事件已得到充分了解，但围食膜直到最近才受到关注。利用谱系追踪技术，我们发现围食膜细胞和盘本身细胞起源于胚胎中的一组共同的前体细胞，并且这些细胞在幼虫早期阶段发生分化。然而，即使在它们的谱系分离后，围食膜细胞和盘本身细胞仍保持空间关系。围食膜在翅盘区域划分为假定的翅、背板和铰链的过程中发挥着重要作用。表皮生长因子受体/ 鼠肉瘤病毒癌基因同源物通路介导围食膜的这一功能。这些关于鳞状上皮细胞和柱状上皮细胞之间信号传导的结果，在使用人类细胞系的体外研究背景下尤为重要，这些研究表明表皮生长因子受体/ 鼠肉瘤病毒癌基因同源物通路在转移和肿瘤进展中发挥作用。
