Renal Division, University Hospital Freiburg, Freiburg, Germany.
PLoS One. 2012;7(7):e40300. doi: 10.1371/journal.pone.0040300. Epub 2012 Jul 6.
Neph molecules are highly conserved immunoglobulin superfamily proteins (IgSF) which are essential for multiple morphogenetic processes, including glomerular development in mammals and neuronal as well as nephrocyte development in D. melanogaster. While D. melanogaster expresses two Neph-like proteins (Kirre and IrreC/Rst), three Neph proteins (Neph1-3) are expressed in the mammalian system. However, although these molecules are highly abundant, their molecular functions are still poorly understood. Here we report on a fly system in which we overexpress and replace endogenous Neph homologs with mammalian Neph1-3 proteins to identify functional Neph protein networks required for neuronal and nephrocyte development. Misexpression of Neph1, but neither Neph2 nor Neph3, phenocopies the overexpression of endogenous Neph molecules suggesting a functional diversity of mammalian Neph family proteins. Moreover, structure-function analysis identified a conserved and specific Neph1 protein motif that appears to be required for the functional replacement of Kirre. Hereby, we establish D. melanogaster as a genetic system to specifically model molecular Neph1 functions in vivo and identify a conserved amino acid motif linking Neph1 to Drosophila Kirre function.
Neph 分子是高度保守的免疫球蛋白超家族蛋白（IgSF），对于包括哺乳动物肾小球发育和果蝇神经元以及肾细胞发育在内的多种形态发生过程至关重要。虽然果蝇表达两种类似于 Neph 的蛋白（Kirre 和 IrreC/Rst），但哺乳动物系统中表达了三种 Neph 蛋白（Neph1-3）。然而，尽管这些分子高度丰富，但它们的分子功能仍知之甚少。在这里，我们报告了一个果蝇系统，我们通过过表达和用哺乳动物 Neph1-3 蛋白替换内源性 Neph 同源物来鉴定神经元和肾细胞发育所需的功能性 Neph 蛋白网络。Neph1 的过表达，但不是 Neph2 或 Neph3 的过表达，模拟了内源性 Neph 分子的过表达，表明哺乳动物 Neph 家族蛋白具有功能多样性。此外，结构功能分析确定了一个保守且特异的 Neph1 蛋白基序，该基序似乎是 Kirre 功能替代所必需的。通过这项研究，我们确立了 D. melanogaster 作为一种遗传系统，可用于专门模拟体内分子 Neph1 的功能，并确定了将 Neph1 与果蝇 Kirre 功能联系起来的保守氨基酸基序。
