Morse Elizabeth M, Sun Xiaowen, Olberding Jordan R, Ha Byung Hak, Boggon Titus J, Calderwood David A
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA.
Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA.
J Cell Sci. 2016 Jan 15;129(2):380-93. doi: 10.1242/jcs.177493. Epub 2015 Nov 23.
The six serine/threonine kinases in the p21-activated kinase (PAK) family are important regulators of cell adhesion, motility and survival. PAK6, which is overexpressed in prostate cancer, was recently reported to localize to cell-cell adhesions and to drive epithelial cell colony escape. Here we report that PAK6 targeting to cell-cell adhesions occurs through its N-terminus, requiring both its Cdc42/Rac interactive binding (CRIB) domain and an adjacent polybasic region for maximal targeting efficiency. We find PAK6 localization to cell-cell adhesions is Cdc42-dependent, as Cdc42 knockdown inhibits PAK6 targeting to cell-cell adhesions. We further find the ability of PAK6 to drive epithelial cell colony escape requires kinase activity and is disrupted by mutations that perturb PAK6 cell-cell adhesion targeting. Finally, we demonstrate that all type II PAKs (PAK4, PAK5 and PAK6) target to cell-cell adhesions, albeit to differing extents, but PAK1 (a type I PAK) does not. Notably, the ability of a PAK isoform to drive epithelial colony escape correlates with its targeting to cell-cell adhesions. We conclude that PAKs have a broader role in the regulation of cell-cell adhesions than previously appreciated.
p21激活激酶（PAK）家族中的六种丝氨酸/苏氨酸激酶是细胞黏附、运动和存活的重要调节因子。最近有报道称，在前列腺癌中过表达的PAK6定位于细胞间黏附部位，并驱动上皮细胞集落逃逸。在此我们报告，PAK6靶向细胞间黏附是通过其N端实现的，这需要其Cdc42/Rac相互作用结合（CRIB）结构域和一个相邻的多碱性区域才能达到最大靶向效率。我们发现PAK6定位于细胞间黏附依赖于Cdc42，因为敲低Cdc42会抑制PAK6靶向细胞间黏附。我们进一步发现，PAK6驱动上皮细胞集落逃逸的能力需要激酶活性，并且会被扰乱PAK6细胞间黏附靶向的突变所破坏。最后，我们证明所有II型PAK（PAK4、PAK5和PAK6）都能靶向细胞间黏附，尽管程度不同，但PAK1（I型PAK）则不能。值得注意的是，一种PAK亚型驱动上皮集落逃逸的能力与其靶向细胞间黏附的能力相关。我们得出结论，PAK在细胞间黏附调节中的作用比之前所认识到的更为广泛。
