Pallavi S K, Shashidhara L S
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007 India.
J Cell Sci. 2005 Aug 1;118(Pt 15):3363-70. doi: 10.1242/jcs.02464.
Understanding the interactions between distinct epithelial cells would help us to understand the development of tissues. Drosophila imaginal discs, which are made up of two types of epithelial cells, provide good model systems for such studies. The disc proper or the columnar epithelial cells are apposed to a layer of squamous epithelial cells (the peripodial membrane). We have examined organization of peripodial and disc proper cells vis-à-vis their polarity since cell polarity plays an important role in the polarized transport of signaling molecules. With the help of polarity-specific cell markers, we have observed that apical surfaces of peripodial and disc proper cells face each other. This provides the cellular basis for the recently demonstrated signaling interactions between peripodial and disc proper cells during disc patterning. We also report significant similarities as well as differences between peripodial and disc proper cells in Engrailed-dependent wingdisc-patterning events, which make them an appropriate model system for studying the mechanism of diffusion of signal molecules, such as Hedgehog. Results with wild-type and two mutant forms of Hedgehog suggest that direct cell-cell contact is a requirement for the movement of wild-type Hedgehog signal and reconfirm that cholesterol-modification of Hedgehog makes it a short-range signaling molecule by restricting its movement.
了解不同上皮细胞之间的相互作用将有助于我们理解组织的发育。果蝇成虫盘由两种类型的上皮细胞组成，为这类研究提供了良好的模型系统。盘本体或柱状上皮细胞与一层鳞状上皮细胞（围膜）相邻。由于细胞极性在信号分子的极性运输中起重要作用，我们研究了围膜细胞和盘本体细胞相对于它们极性的组织情况。借助极性特异性细胞标记物，我们观察到围膜细胞和盘本体细胞的顶端表面相互面对。这为最近在盘图案形成过程中围膜细胞和盘本体细胞之间所证明的信号相互作用提供了细胞基础。我们还报告了在依赖于Engrailed的翅盘图案形成事件中围膜细胞和盘本体细胞之间的显著相似性和差异，这使它们成为研究信号分子（如刺猬蛋白）扩散机制的合适模型系统。野生型和两种突变形式的刺猬蛋白的结果表明，直接的细胞间接触是野生型刺猬蛋白信号移动的必要条件，并再次证实刺猬蛋白的胆固醇修饰通过限制其移动使其成为一种短程信号分子。
