title: Phosphorylation of phosphatidylinositol 4-phosphate 5-kinase γ by Akt regulates its interaction with talin and focal adhesion dynamics.
abstract: The type I phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family members and their lipid product, phosphatidylinositol 4,5-bisphosphate (PIP2) are important regulators of actin cytoskeleton. PIP5Kγ 90kDa (PIP5Kγ90), an isoform of PIP5K, localizes to focal adhesions (FAs) and is activated via its interaction with the cytoskeletal protein, talin. Currently, regulatory signaling pathways of talin-PIP5Kγ90 interaction related to FA dynamics and cell motility are not well understood. Considering the presence of Akt consensus motifs in PIP5Kγ90, we examined a potential link of Akt activation to talin-PIP5Kγ90 interaction. We found that Akt phosphorylated PIP5Kγ90 specifically at serine 555 (S555) in vitro and in epidermal growth factor (EGF)-treated cells phosphoinositide 3-kinase-dependently. EGF treatment suppressed talin-PIP5Kγ90 interaction and PIP2 levels. Similarly, a phosphomimetic mutant (S555D), but not non-phosphorylatable mutant (S555A), of PIP5Kγ90 had reduced talin binding affinity, lowered PIP2 levels, and was dislocated from FAs. The S555D mutant also caused decreases in actin stress fibers and vinculin-positive FAs. Moreover, assembly and disassembly of FAs were enhanced by S555D expression and EGF-induced cell migration was relatively low in S555A-expressing cells compared to wild-type-expressing cells. PIP5Kγ87, a PIP5Kγ splice variant lacking the talin binding motif, was phosphorylated by Akt, which, however, hardly affected PIP2 levels. Taken together, our results suggested that Akt-mediated PIP5Kγ90 S555 phosphorylation is a novel regulatory point for talin binding to control PIP2 level at the FAs, thereby modulating FA dynamics and cell motility.
authors.affiliation: Department of Biomedical Sciences, Neuroscience Graduate Program, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea. Electronic address: leoanh_1811@yahoo.com.
authors.forename: Oanh Thi Tu
authors.initials: OT
authors.lastname: Le
authors.affiliation: Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Oh Yeon
authors.initials: OY
authors.lastname: Cho
authors.affiliation: Department of Biomedical Sciences, Neuroscience Graduate Program, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea.
authors.forename: Mai Hoang
authors.initials: MH
authors.lastname: Tran
authors.affiliation: Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors.forename: Jung Ah
authors.initials: JA
authors.lastname: Kim
authors.affiliation: Department of Physiology and Biomedical Sciences, Seoul National University College of Medicine, Seoul 110-799, South Korea; Biomembrane Plasticity Research Center, Seoul National University College of Medicine, Seoul 110-799, South Korea. Electronic address: sunghoe@snu.ac.kr.
authors.forename: Sunghoe
authors.initials: S
authors.lastname: Chang
authors.affiliation: Department of Biomedical Sciences, Neuroscience Graduate Program, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea; Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea; Department of Pharmacology, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea. Electronic address: jouilo@ajou.ac.kr.
authors.forename: Ilo
authors.initials: I
authors.lastname: Jou
authors.affiliation: Department of Biomedical Sciences, Neuroscience Graduate Program, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea; Chronic Inflammatory Disease Research Center, Ajou University School of Medicine, Suwon, Gyeonggi 443-721, South Korea. Electronic address: sangyoon@ajou.ac.kr.
authors.forename: Sang Yoon
authors.initials: SY
authors.lastname: Lee
mesh_terms: D017398:Alternative Splicing / Q000502:physiology*; D019943:Amino Acid Substitution; D002465:Cell Movement / Q000502:physiology*; D022001:Focal Adhesions / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010766:Phosphorylation / Q000502:physiology; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D016608:Talin / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D016608:Talin; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D051057:Proto-Oncogene Proteins c-akt
keywords: Akt; Focal adhesion; Phosphatidylinositol 4,5-bisphosphate; Phosphatidylinositol 4-phosphate 5-kinase γ; Phosphorylation; Talin