Munro Michelle, Akkam Yazan, Curtin Kathryn D
Department of Biological Sciences, 601 SCEN, Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR 72701, USA.
Gene. 2010 Jan 1;449(1-2):50-8. doi: 10.1016/j.gene.2009.09.004. Epub 2009 Sep 25.
Drosophila basigin is a cell-surface glycoprotein of the Ig superfamily and a member of a protein family that includes mammalian EMMPRIN/CD147/basigin, neuroplastin, and embigin. Our previous work on Drosophila basigin has shown that it is required for normal photoreceptor cell structure and normal neuron-glia interaction in the fly visual system. Specifically, the photoreceptor neurons of mosaic animals that are mutant in the eye for basigin show altered cell structure with nuclei, mitochondria and rER misplaced and variable axon diameter compared to wild-type. In addition, glia cells in the optic lamina that contact photoreceptor axons are misplaced and show altered structure. All these defects are rescued by expression of either transgenic fly basigin or transgenic mouse basigin in the photoreceptors demonstrating that mouse basigin can functionally replace fly basigin. To determine what regions of the basigin protein are required for each of these functions, we have created mutant basigin transgenes coding for proteins that are altered in conserved residues, introduced these into the fly genome, and tested them for their ability to rescue both photoreceptor cell structure defects and neuron-glia interaction defects of basigin. The results suggest that the highly conserved transmembrane domain and the extracellular domains are crucial for basigin function in the visual system while the short intracellular tail may not play a role in these functions.
果蝇basigin是免疫球蛋白超家族的一种细胞表面糖蛋白，是一个蛋白质家族的成员，该家族包括哺乳动物的EMMPRIN/CD147/basigin、神经塑蛋白和embigin。我们之前对果蝇basigin的研究表明，它是果蝇视觉系统中正常光感受器细胞结构和正常神经元-神经胶质细胞相互作用所必需的。具体而言，与野生型相比，眼睛中basigin基因发生突变的嵌合体动物的光感受器神经元显示出细胞结构改变，细胞核、线粒体和粗面内质网位置异常，轴突直径可变。此外，与光感受器轴突接触的视叶中的神经胶质细胞位置异常，结构改变。通过在光感受器中表达转基因果蝇basigin或转基因小鼠basigin可以挽救所有这些缺陷，这表明小鼠basigin可以在功能上替代果蝇basigin。为了确定basigin蛋白的哪些区域对于这些功能是必需的，我们创建了编码保守残基发生改变的蛋白质的突变basigin转基因，将其导入果蝇基因组，并测试它们挽救basigin的光感受器细胞结构缺陷和神经元-神经胶质细胞相互作用缺陷的能力。结果表明，高度保守的跨膜结构域和细胞外结构域对于basigin在视觉系统中的功能至关重要，而短的细胞内尾巴可能在这些功能中不起作用。
