Binding of the extreme carboxyl-terminus of PAK-interacting exchange factor beta (beta PIX) to myosin 18A (MYO18A) is required for epithelial cell migration

作者：Hsu Rae Mann; Hsieh Ya Ju; Yang Tsung Han; Chiang Yi Chien; Kan Chih Yen; Lin Yu Tsuen; Chen Jeng Ting; Yu Jau Song^*

来源：Biochimica et Biophysica Acta-Molecular Cell Research, 2014, 1843(11): 2513-2527.

DOI：10.1016/j.bbamcr.2014.06.023

• MYO18A
• beta PIX
• PAK2
• GIT1
• Focal adhesion
• Cell migration

The PAK2/beta PIX/GIT1 (p21-activated kinase 2/PAK-interacting exchange factor-beta/G protein-coupled receptor kinase-interactor 1) complex has been shown to distribute to both membrane ruffles and focal adhesions of cells, where it plays an important role in regulating focal adhesion turnover. However, the detailed mechanism underlying this regulation is largely unknown. We previously reported that MYO18A alpha interacts via its carboxyl terminus with the PAK2/beta PIX/GIT1 complex through direct binding to beta PIX, and that knockdown of MYO18A alpha in epithelial cells causes accumulation of the complex in focal adhesions and decreased cell migration ability (Hsu et al., 2010). The current study characterized the detailed MYO18A alpha-beta PIX interaction mechanism and the biological significance of this interaction. We found that deletion of the carboxyl-terminal globular domain of MYO18A alpha profoundly altered the cellular localization of beta PIX and inhibited cell migration. beta PIX interacts through its most carboxyl-terminus, PAWDETNL (639-646), with MYO18A alpha and partially colocalized with MYO18A alpha in membrane ruffles of cells, whereas beta PIX1-638, a mutant with deletion of PAWDETNL, accumulated in focal adhesions. Both focal adhesion numbers and area in beta PIX1-638-expressing cells were greater than those in cells expressing wild-type beta PIXFL. Further experiments using deletion mutants of MYO18A and beta PIX showed that disruption of MYO18A-beta PIX interaction not only impaired cell motility but also decreased Rac1 activity. Collectively, our data unravel the interaction regions between MYO18A and beta PIX and provide evidence for the critical role of this interaction in regulating cellular localization of beta PIX, Rac1 activity, and adhesion and migration in epithelial cells.

• 出版日期2014-11
• 单位长春大学