Ubiquitination of PIPKIγ90 by HECTD1 regulates focal adhesion dynamics and cell migration.

PIPKIγ90 binds talin and localizes at focal adhesions (FAs). PIP2 generated by PIPKIγ90 is essential for FA formation and cell migration. On the other hand, PIPKIγ90 and the β integrin tail compete for overlapping binding sites on talin. Enhanced PIPKIγ90-talin interaction suppresses talin binding to the β integrin. It is unknown how PIPKIγ90 is removed from the PIPKIγ90-talin complex after on-site PIP2 production during cell migration. Here we show that PIPKIγ90 is a substrate for HECTD1, an E3 ubiquitin ligase regulating cell migration. HECTD1 ubiquitinated PIPKIγ90 at Lys97 and resulted in PIPKIγ90 degradation. Expression of PIPKIγ90(K97R) enhanced PIP2 and PIP3 production and inhibited FA assembly and disassembly, cancer cell migration, invasion and metastasis. Interestingly, mutation at Trp647 abolished the inhibition of PIPKIγ90(K97R) on FA dynamics and partially rescued cancer cell migration and invasion. Thus, cycling PIPKIγ90 ubiquitination by HECTD1 and consequent degradation remove PIPKIγ90 from talin after on-site PIP2 production, providing an essential regulatory mechanism for FA dynamics and cell migration.
J. Cell. Sci. Apr. 09, 2013; 0(0); [PUBMED:23572508]
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