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Updated: Jul 21, 2026

Induction of Adhesion-dependent Signals Using Low-intensity Ultrasound
Published on: May 8, 2012
Mitotic dissociation of IQGAP1 from Rac-bound beta1-integrin is mediated by protein phosphatase 2A
Eri Nakajima1, Katsuo Suzuki, Kazuhide Takahashi
1Department of Biochemistry, Kanagawa Cancer Center Research Institute, 1-1-2 Nakao, Asahi-ku, Yokohama 241-0815, Japan.
Abstract:
Assembly of F-actin that links with beta1-integrin during the G1 phase of cell cycle is released from beta1-integrin and disrupted at mitosis. However, it remains unclear how F-actin assembly to which beta1-integrin anchors is cell cycle-dependently regulated. We show that beta1-integrin was co-immunoprecipitated and co-localized with a small GTPase Rac and its effector IQGAP1, along with PP2A-AC, in HME cells during G1. When the cells were accumulated to G2/M, the co-immunoprecipitation or co-localization of IQGAP1 and PP2A-AC with beta1-integrin was lost, leaving Rac bound to beta1-integrin. The dissociated IQGAP1 was co-immunoprecipitated with the concomitantly dissociated PP2A-A and -C, indicating the complex formation among the proteins in G2/M cells. Falling ball viscometric assays revealed that only IQGAP1-bound beta1-integrin-Rac in G1 cells exhibited an enhanced F-actin cross-linking activity. The results suggest that the mitotic loss of F-actin assembly to which beta1-integrin anchors is due to PP2A-mediated dissociation of IQGAP1 from Rac-bound beta1-integrin.
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