Dynamin 1 is important for microtubule organization and stabilization in glomerular podocytes
The Mon La, Hiromi Tachibana, Shun‐Ai Li, Tadashi Abe, Sayaka Seiriki, Hikaru Nagaoka, Eizo Takashima, Tetsuya Takeda, Daisuke Ogawa, Shin‐ichi Makino, Katsuhiko Asanuma, Masami Watanabe, Xuefei Tian, Shuta Ishibe, Ayuko Sakane, Takuya Sasaki, Jun Wada, Kohji Takei, Hiroshi Yamada
Abstract
Abstract Dynamin 1 is a neuronal endocytic protein that participates in vesicle formation by scission of invaginated membranes. Dynamin 1 is also expressed in the kidney; however, its physiological significance to this organ remains unknown. Here, we show that dynamin 1 is crucial for microtubule organization and stabilization in glomerular podocytes. By immunofluorescence and immunoelectron microscopy, dynamin 1 was concentrated at microtubules at primary processes in rat podocytes. By immunofluorescence of differentiated mouse podocytes (MPCs), dynamin 1 was often colocalized with microtubule bundles, which radially arranged toward periphery of expanded podocyte. In dynamin 1‐depleted MPCs by RNAi, α‐tubulin showed a dispersed linear filament‐like localization, and microtubule bundles were rarely observed. Furthermore, dynamin 1 depletion resulted in the formation of discontinuous, short acetylated α‐tubulin fragments, and the decrease of microtubule‐rich protrusions. Dynamins 1 and 2 double‐knockout podocytes showed dispersed acetylated α‐tubulin and rare protrusions. In vitro, dynamin 1 polymerized around microtubules and cross‐linked them into bundles, and increased their resistance to the disassembly‐inducing reagents Ca 2+ and podophyllotoxin. In addition, overexpression and depletion of dynamin 1 in MPCs increased and decreased the nocodazole resistance of microtubules, respectively. These results suggest that dynamin 1 supports the microtubule bundle formation and participates in the stabilization of microtubules.