The assembly of focal adhesions (FAs) at the leading edge of the cell is important for cell migration, and FA misregulation has been implicated in cancer metastasis. A number of factors are known to regulate FAs, including paxilin, talin, SMURF1 and phosphatidylinositol 4-phosphate 5-kinase type I γ (PIPKIγ90, also known as PIP5K1C), a key enzyme involved in the synthesis of phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2], which is also crucial for FA formation. PIPKIγ90 interacts with talin and competes with the β-integrin tail for the same binding site on talin. However, it is unclear how PIPKIγ90 can bind talin to produce PtdIns(4,5)P2 at the site of FA formation without inhibiting the interaction between the β-integrin tail and talin that is also required. It is also not known how PIPKIγ90 is removed from FAs after production of PtdIns(4,5)P2. Here (p. 2617), Cai Huang and collaborators show that PIPKIγ90 is ubiquitylated by the E3 ubiquitin ligase HECTD1 at Lys97, resulting in its degradation. Consequently, when they mutate Lys97 or knockdown HECTD1, PtdIns(4,5)P2 production is enhanced and results in inhibition of FA turnover and of cell migration and invasion. On the basis of these results, the authors propose a model in which PIPKIγ90-mediated synthesis of PtdIns(4,5)P2 at FAs is modulated through PIPKIγ90 degradation and, hence, regulates focal adhesion turnover and migration.
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IN THIS ISSUE| 15 June 2013
PIPKIγ90 turnover regulates focal adhesion dynamics
Online Issn: 1477-9137
Print Issn: 0021-9533
© 2013. Published by The Company of Biologists Ltd
J Cell Sci (2013) 126 (12): e1202.
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PIPKIγ90 turnover regulates focal adhesion dynamics. J Cell Sci 15 June 2013; 126 (12): e1202. doi:
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