Ichimura Koichiro, Kurihara Hidetake, Sakai Tatsuo
Department of Anatomy, Juntendo University School of Medicine, Hongo, Tokyo, Japan.
J Histochem Cytochem. 2003 Dec;51(12):1589-600. doi: 10.1177/002215540305101203.
The foot processes of podocytes possess abundant microfilaments and modulate glomerular filtration. We investigated the actin filament organization of foot processes in adult rat podocytes and the formation of the actin cytoskeletal system of immature podocytes during glomerulogenesis. Electron microscopy revealed two populations of actin cytoskeletons in foot processes of adult podocytes. One is the actin bundle running above the level of slit diaphragms and the other is the cortical actin network located beneath the plasmalemma. Immunogold labeling for actin-binding proteins demonstrated that alpha-actinin and synaptopodin were localized in the actin bundle, whereas cortactin was in the cortical actin network. Immunofluorescence labeling for actin-binding proteins in immature podocyte showed that alpha-actinin was localized at the level of the junctional complex, whereas cortactin was distributed beneath the entire plasmalemma. Synaptopodin was first observed along the basal plasmalemma from the advanced S-shaped body to the capillary loop stage. We conclude that foot processes have specialized actin filamentous organization and that its establishment is associated with the expression and redistribution of actin-binding proteins during development.
足细胞的足突含有丰富的微丝，并调节肾小球滤过。我们研究了成年大鼠足细胞足突的肌动蛋白丝组织以及肾小球发生过程中未成熟足细胞肌动蛋白细胞骨架系统的形成。电子显微镜显示成年足细胞足突中有两种肌动蛋白细胞骨架。一种是位于裂孔隔膜水平上方的肌动蛋白束，另一种是位于质膜下方的皮质肌动蛋白网络。对肌动蛋白结合蛋白的免疫金标记表明，α-辅肌动蛋白和突触足蛋白定位于肌动蛋白束中，而皮层肌动蛋白则位于皮质肌动蛋白网络中。对未成熟足细胞中肌动蛋白结合蛋白的免疫荧光标记显示，α-辅肌动蛋白定位于连接复合体水平，而皮层肌动蛋白分布于整个质膜下方。突触足蛋白首先在从晚期S形体到毛细血管袢阶段的基底质膜上被观察到。我们得出结论，足突具有特殊的肌动蛋白丝组织，其形成与发育过程中肌动蛋白结合蛋白的表达和重新分布有关。
