Palladin is a dynamic actin-associated protein in podocytes
Palladin is a dynamic actin-associated protein in podocytes
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DOI：
10.1038/ki.2008.486
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发表时间：
2009-01-01
影响因子：
19.6
通讯作者：
Endlich, Karlhans
中科院分区：
文献类型：
--
作者：
Endlich, Nicole;Schordan, Eric;Endlich, Karlhans
帕拉丁是一种细胞骨架蛋白，对应激纤维的形成具有重要功能，存在于发育和成熟的组织中，包括肾脏。为了确定其在肾脏中的作用，我们测量了其在小鼠肾脏中的表达，发现它与f -肌动蛋白共定位于肾动脉血管平滑肌细胞、系膜细胞和足细胞中，但不在小管上皮中。利用免疫电镜，我们证实足细胞中存在帕拉丁。在培养的小鼠足细胞中，钯素与f -肌动蛋白共定位于应力纤维密集区域、局灶黏附、细胞-细胞接触和运动细胞边缘。转染帕拉丁的n端一半靶向足细胞中含有f -肌动蛋白的结构，而c端一半在细胞核中积累，使用leptomycin B阻断核输出后，培养细胞中内源性帕拉丁也发现了这一结果。绿色荧光蛋白（GFP）标记的palladin在培养的足细胞受表皮生长因子刺激后的动态环状f -肌动蛋白结构和褶边中发现。通过转染反义结构体抑制钯素的表达可减少环状结构的形成。光漂白分析表明，GFP-palladin在应力纤维的黏附区和密集区可翻转10 s，表明palladin是一种动态支架蛋白。我们的研究表明，palladin在足细胞中表达，并在肌动蛋白动力学中起重要作用。
Palladin, a cytoskeletal protein with essential functions for stress fiber formation, is found in developing and mature tissues, including the kidney. To define its role in the kidney, we measured its expression in mouse kidney and found it co-localized with F-actin in smooth muscle cells of renal arterial vessels, mesangial cells, and podocytes but not in tubular epithelium. Using immunoelectron microscopy, we confirmed that palladin was present in podocytes. In cultured mouse podocytes, palladin co-localized with F-actin in dense regions of stress fibers, focal adhesions, cell-cell contacts and motile cell margins. Transfection with the N-terminal half of palladin targeted it to F-actin-containing structures in podocytes while the C-terminal half accumulated in the nucleus, a result also found for endogenous palladin in cultured cells after leptomycin B was used to block nuclear export. Green fluorescent protein (GFP)-tagged palladin was found in dynamic ring-like F-actin structures and ruffles in cultured podocytes after stimulation with epidermal growth factor. Inhibition of palladin expression by transfection of an antisense construct reduced the formation of ring-like structures. Photo-bleaching analysis showed that GFP-palladin turned over with a half-time of 10 s in focal adhesions and dense regions of stress fibers, suggesting that palladin is a dynamic scaffolding protein. Our study shows that palladin is expressed in podocytes and plays an important role in actin dynamics.