Affixin interacts with alpha-actinin and mediates integrin signaling for reorganization of F-actin induced by initial cell-substrate interaction.
The linking of integrin to cytoskeleton is a critical event for an effective cell migration. Previously, we have reported that a novel integrin-linked kinase (ILK)-binding protein, affixin, is closely involved in the linkage between integrin and cytoskeleton in combination with ILK. In the present work, we demonstrated that the second calponin homology domain of affixin directly interacts with alpha-actinin in an ILK kinase activity-dependent manner, suggesting that integrin-ILK signaling evoked by substrate adhesion induces affixin-alpha-actinin interaction. The overexpression of a peptide corresponding to the alpha-actinin-binding site of affixin as well as the knockdown of endogenous affixin by small interference RNA resulted in the blockade of cell spreading. Time-lapse observation revealed that in both experiments cells were round with small peripheral blebs and failed to develop lamellipodia, suggesting that the ILK-affixin complex serves as an integrin-anchoring site for alpha-actinin and thereby mediates integrin signaling to alpha-actinin, which has been shown to play a critical role in actin polymerization at focal adhesions.
Yamaji
Satoshi
S
The First Dept. of Internal Medicine, Yokohama City University School of Medicine, 3-9 Fuku-ura, Kanazawa-ku, Yokohama 236-0004, Japan.
Suzuki
Atsushi
A
Kanamori
Heiwa
H
Mishima
Wataru
W
Yoshimi
Ryusuke
R
Takasaki
Hirotaka
H
Takabayashi
Maki
M
Fujimaki
Katsumichi
K
Fujisawa
Shin
S
Ohno
Shigeo
S
Ishigatsubo
Yoshiaki
Y
D000185:Actinin / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D016466:CHO Cells; D019556:COS Cells; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D022081:Cell Surface Extensions / Q000378:metabolism* / Q000648:ultrastructure; D006224:Cricetinae; D015536:Down-Regulation / Q000235:genetics; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D008840:Microfilament Proteins; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D011554:Pseudopodia / Q000378:metabolism / Q000648:ultrastructure; D034622:RNA Interference; D015398:Signal Transduction / Q000502:physiology; D000099200:Scaffold Protein ILK; D000096985:Calponins
D000185:Actinin; D000199:Actins; D016023:Integrins; D008840:Microfilament Proteins; D010455:Peptides; D017346:Protein Serine-Threonine Kinases; D000099200:Scaffold Protein ILK; C486590:PARVA protein, human; D000096985:Calponins; C486591:PARVB protein, human