Bairstow Shawn F, Ling Kun, Anderson Richard A
Department of Pharmacology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
J Biol Chem. 2005 Jun 24;280(25):23884-91. doi: 10.1074/jbc.M500576200. Epub 2005 Apr 22.
Tyrosine phosphorylation plays a critical role in many regulatory aspects of cellular signaling, and dephosphorylation of phosphotyrosine residues is crucial for termination of signals initiated by tyrosine kinases. Previous work has shown that the tyrosine kinase Src phosphorylates Tyr644 on phosphatidylinositol phosphate kinase type I (PIPKI) gamma661 in a focal adhesion kinase-dependent manner. Phosphorylation of this residue is essential for high affinity binding of PIPKI gamma661 to the focal adhesion protein talin and for targeting of PIPKI gamma661 to focal adhesions. A yeast two-hybrid screen performed with the C-terminal 178-amino acid tail of PIPKI gamma661 identified an interaction with the phosphatase domain of the tyrosine phosphatase Shp-1. The interaction between PIPKI gamma661 and Shp-1 was confirmed via co-immunoprecipitation from HEK293 cell lysates. In addition, Src-phosphorylated PIPKI gamma661 is a substrate for Shp-1, and Shp-1 modulates both the association between PIPKI gamma661 and talin and the targeting of PIPKI gamma661 to focal adhesions in mammalian cells. Finally, we showed that Shp-1 phosphatase activity is inhibited by the product of PIPKI gamma661, phosphatidylinositol 4,5-bisphosphate, in vitro. These combined results suggest a model in which the reciprocal actions of Src tyrosine kinase and Shp-1 tyrosine phosphatase dynamically regulate the association between PIPKI gamma661 and talin.
酪氨酸磷酸化在细胞信号传导的许多调节方面发挥着关键作用，而磷酸酪氨酸残基的去磷酸化对于由酪氨酸激酶启动的信号终止至关重要。先前的研究表明，酪氨酸激酶Src以粘着斑激酶依赖的方式使I型磷脂酰肌醇磷酸激酶（PIPKI）γ661上的Tyr644磷酸化。该残基的磷酸化对于PIPKIγ661与粘着斑蛋白踝蛋白的高亲和力结合以及PIPKIγ661靶向粘着斑至关重要。用PIPKIγ661的C末端178个氨基酸尾巴进行的酵母双杂交筛选确定了与酪氨酸磷酸酶Shp-1的磷酸酶结构域的相互作用。通过从HEK293细胞裂解物中共免疫沉淀证实了PIPKIγ661与Shp-1之间的相互作用。此外，Src磷酸化的PIPKIγ661是Shp-1的底物，并且Shp-1调节哺乳动物细胞中PIPKIγ661与踝蛋白之间的结合以及PIPKIγ661靶向粘着斑。最后，我们表明在体外PIPKIγ661的产物磷脂酰肌醇4,5-二磷酸抑制Shp-1磷酸酶活性。这些综合结果提示了一个模型，其中Src酪氨酸激酶和Shp-1酪氨酸磷酸酶的相互作用动态调节PIPKIγ661与踝蛋白之间的结合。
