Nuclear FAK Promotes Cell Proliferation and Survival through FERM-Enhanced p53 Degradation

Department of Reproductive Medicine, Moores Cancer Center, University of California, San Diego, 3855 Health Sciences Drive, MC0803, La Jolla, CA 92093, USA.
Molecular Cell (Impact Factor: 14.02). 02/2008; 29(1):9-22. DOI: 10.1016/j.molcel.2007.11.031
Source: PubMed


FAK is known as an integrin- and growth factor-associated tyrosine kinase promoting cell motility. Here we show that, during mouse development, FAK inactivation results in p53- and p21-dependent mesodermal cell growth arrest. Reconstitution of primary FAK-/-p21-/- fibroblasts revealed that FAK, in a kinase-independent manner, facilitates p53 turnover via enhanced Mdm2-dependent p53 ubiquitination. p53 inactivation by FAK required FAK FERM F1 lobe binding to p53, FERM F2 lobe-mediated nuclear localization, and FERM F3 lobe for connections to Mdm2 and proteasomal degradation. Staurosporine or loss of cell adhesion enhanced FERM-dependent FAK nuclear accumulation. In primary human cells, FAK knockdown raised p53-p21 levels and slowed cell proliferation but did not cause apoptosis. Notably, FAK knockdown plus cisplatin triggered p53-dependent cell apoptosis, which was rescued by either full-length FAK or FAK FERM re-expression. These studies define a scaffolding role for nuclear FAK in facilitating cell survival through enhanced p53 degradation under conditions of cellular stress.

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Available from: Ssang-Taek Steve Lim, Apr 08, 2015
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    • "To prepare whole-cell lysates, cells were washed in cold PBS and lysed in RIPA buffer. Cytoplasmic and nuclear extracts were prepared as described in Lim et al. (2008). Lysates were resolved by gel electrophoresis, transferred to nitrocellulose, and probed with respective antibodies. "
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    • "To ultimately validate that it is the kinase activity that mediates FAK/PYK2 regulation of Wnt/β-catenin signaling, we examined GSK3β Y216 phosphorylation-dependent activation of Wnt/β-catenin signaling in FAK kinase-deficient MEFs (FAK R454/R454 knockin MEFs). A knock-in point mutation of lysine 454 to arginine within the catalytic domain inactivates FAK kinases activity (Lim et al., 2010) (Figure 4B, represented by abolished phosphorylation of FAK Y397 ) but leaves FAK's scaffolding activity intact (Lim et al., 2008). Consistent with our finding that FAK and PYK2 function redundantly in phosphorylating GSK3, despite of suppressed FAK activity in FAK R454/R454 MEFs, KD of PYK2 was required to inhibit GSK3β Y216 phosphorylation. "
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