Stabilization of actin bundles by a Dynamin 1/cortactin ring complex is necessary for growth cone filopodia

Hiroshi Yamada, Tadashi Abe, Ayano Satoh, Nana Okazaki, Shota Tago, Kinue Kobayashi, Yumi Yoshida, Yoshiya Oda, Masami Watanabe, Kazuhito Tomizawa, Hideki Matsui, Kohji Takei

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Dynamin GTPase, a key molecule in endocytosis, mechanically severs the invaginated membrane upon GTP hydrolysis. Dynamin functions also in regulating actin cytoskeleton, but the mechanisms are yet to be defined. Here we show that dynamin 1, a neuronal isoform of dynamin, and cortactin form ring complexes, which twine around F-actin bundles and stabilize them. By negative-staining EM, dynamin 1 cortactin complexes appeared as "open" or "closed" rings depending on guanine nucleotide conditions. By pyrene actin assembly assay, dynamin 1 stimulated actin assembly in mouse brain cytosol. In vitro incubation of F-actin with both dynamin 1 and cortactin led to the formation of long and thick actin bundles, on which dynamin 1 and cortactin were periodically colocalized in puncta. A depolymerization assay revealed that dynamin 1 and cortactin increased the stability of actin bundles, most prominently in the presence of GTP. In rat cortical neurons and human neuroblastoma cell line, SH-SY5Y, both dynamin 1 and cortactin localized on actin filaments and the bundles at growth cone filopodia as revealed by immunoelectron microscopy. In SH-SY5Y cell, acute inhibition of dynamin 1 by application of dynamin inhibitor led to growth cone collapse. Cortactin knockdown also reduced growth cone filopodia. Together, our results strongly suggest that dynamin 1 and cortactin ring complex mechanically stabilizes F-actin bundles in growth cone filopodia. Thus, the GTPase-dependent mechanochemical enzyme property of dynamin is commonly used both in endocytosis and regulation of F-actin bundles by a dynamin 1 cortactin complex.

Original languageEnglish
Pages (from-to)4514-4526
Number of pages13
JournalJournal of Neuroscience
Volume33
Issue number10
DOIs
Publication statusPublished - Mar 6 2013

ASJC Scopus subject areas

  • Neuroscience(all)

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