Actin filament organization of foot processes in vertebrate glomerular podocytes
Actin filament organization of foot processes in vertebrate glomerular podocytes
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DOI：
10.1007/s00441-007-0440-4
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发表时间：
2007-09-01
影响因子：
3.6
通讯作者：
Sakai, Tatsuo
中科院分区：
文献类型：
--
作者：
Ichimura, Koichiro;Kurihara, Hidetake;Sakai, Tatsuo
我们研究了八种脊椎动物（七鳃鳗、鲤鱼、蝾螈、青蛙、壁虎、海龟、鹌鹑和大鼠）足细胞足突中肌动蛋白丝的组织和肌动蛋白结合蛋白（α -肌动蛋白和皮质蛋白）的免疫定位。在足突中发现了三种类型的肌动蛋白细胞骨架。(1)在这里研究的所有物种中都发现了一个皮质肌动蛋白网络，其中皮质蛋白填充在质膜和下面描述的其他肌动蛋白细胞骨架之间的空间。这些数据表明，皮质肌动蛋白网络是脊椎动物足细胞足突形成和维持的最小必需肌动蛋白细胞骨架。(2)只在鹌鹑和大鼠中观察到沿狭缝横膈膜上方足突纵轴存在与a-肌动蛋白的肌动蛋白束。(3)除鹌鹑和大鼠外，其他物种的肌动蛋白束中肌动蛋白丝的数量比肌动蛋白束少得多，但频率不同。这些发现表明肌动蛋白束是一种额外的肌动蛋白细胞骨架，反映了鹌鹑和大鼠肾小球特有的功能状态。考虑到鸟类和哺乳动物肾小球内压力较高，滤过屏障极薄，足突可能主要保护较薄的滤过屏障免受鹌鹑和大鼠肾小球内压力较高的影响。因此，我们认为肌动蛋白束在过滤屏障的机械保护中起着至关重要的作用。此外，肌动蛋白束可能是肌动蛋白束的潜在前体。
We investigated the actin filament organization and immunolocalization of actin-binding proteins (alpha-actinin and cortactin) in the podocyte foot processes of eight vertebrate species (lamprey, carp, newt, frog, gecko, turtle, quail, and rat). Three types of actin cytoskeleton were found in these foot processes. (1) A cortical actin network with cortactin filling the space between the plasma membrane and the other actin cytoskeletons described below was found in all of the species examined here. The data indicated that the cortical actin network was the minimal essential actin cytoskeleton for the formation and maintenance of the foot processes in vertebrate podocytes. (2) An actin bundle with a-actinin existing along the longitudinal axis of foot process above the level of slit diaphragms was only observed in quail and rat. (3) An actin fascicle consisting of much fewer numbers of actin filaments than that of the actin bundle was observed in the species other than quail and rat, but at various frequencies. These findings suggest that the actin bundle is an additional actin cytoskeleton reflecting a functional state peculiar to quail and rat glomeruli. Considering the higher intraglomerular pressure and the extremely thin filtration barrier in birds and mammals, the foot processes probably mainly protect the thinner filtration barrier from the higher internal pressure occurring in quail and rat glomeruli. Therefore, we consider that the actin bundle plays a crucial role in the mechanical protection of the filtration barrier. Moreover, the actin fascicle may be a potential precursor of the actin bundle.