Ubiquitylation of phosphatidylinositol 4-phosphate 5-kinase type I γ by HECTD1 regulates focal adhesion dynamics and cell migration

Phosphatidylinositol 4-phosphate 5-kinase type I gamma (PIPKI gamma 90) binds talin and localizes at focal adhesions (FAs). Phosphatidylinositol (4,5)-bisphosphate (PIP2) generated by PIPKI gamma 90 is essential for FA formation and cell migration. On the other hand, PIPKI gamma 90 and the beta-integrin tail compete for overlapping binding sites on talin. Enhanced PIPKI gamma 90-talin interaction suppresses talin binding to the beta-integrin. It is unknown how PIPKI gamma 90 is removed from the PIPKI gamma 90-talin complex after on-site PIP2 production during cell migration. Here we show that PIPKI gamma 90 is a substrate for HECTD1, an E3 ubiquitin ligase regulating cell migration. HECTD1 ubiquitinated PIPKI gamma 90 at lysine 97 and resulted in PIPKI gamma 90 degradation. Expression of the mutant PIPKI gamma 90(K97R) enhanced PIP2 and PIP3 production, inhibited FA assembly and disassembly and inhibited cancer cell migration, invasion and metastasis. Interestingly, mutation at tryptophan 647 abolished the inhibition of PIPKI gamma 90(K97R) on FA dynamics and partially rescued cancer cell migration and invasion. Thus, cycling PIPKI gamma 90 ubiquitylation by HECTD1 and consequent degradation remove PIPKI gamma 90 from talin after on-site PIP2 production, providing an essential regulatory mechanism for FA dynamics and cell migration.