Child Study Center, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
J Biol Chem. 2012 Jun 15;287(25):20942-56. doi: 10.1074/jbc.M112.368654. Epub 2012 Apr 27.
Proline-rich tyrosine kinase 2 (Pyk2) is a member of the focal adhesion kinase family and is highly expressed in brain and hematopoietic cells. Pyk2 plays diverse functions in cells, including the regulation of cell adhesion, migration, and cytoskeletal reorganization. In the brain, it is involved in the induction of long term potentiation through regulation of N-methyl-d-aspartate receptor trafficking. This occurs through the phosphorylation and activation of Src family tyrosine kinase members, such as Fyn, that phosphorylate GluN2B at Tyr(1472). Phosphorylation at this site leads to exocytosis of GluN1-GluN2B receptors to synaptic membranes. Pyk2 activity is modulated by phosphorylation at several critical tyrosine sites, including Tyr(402). In this study, we report that Pyk2 is a substrate of striatal-enriched protein-tyrosine phosphatase (STEP). STEP binds to and dephosphorylates Pyk2 at Tyr(402). STEP KO mice showed enhanced phosphorylation of Pyk2 at Tyr(402) and of the Pyk2 substrates paxillin and ASAP1. Functional studies indicated that STEP opposes Pyk2 activation after KCl depolarization of cortical slices and blocks Pyk2 translocation to postsynaptic densities, a key step required for Pyk2 activation and function. This is the first study to identify Pyk2 as a substrate for STEP.
脯氨酸丰富的酪氨酸激酶 2（Pyk2）是粘着斑激酶家族的成员，在大脑和造血细胞中高度表达。Pyk2 在细胞中发挥多种功能，包括调节细胞黏附、迁移和细胞骨架重排。在大脑中，它通过调节 N-甲基-D-天冬氨酸受体转运来参与长时程增强的诱导。这是通过 Src 家族酪氨酸激酶成员（如 Fyn）的磷酸化和激活来实现的，它们将 GluN2B 磷酸化在 Tyr（1472）。该位点的磷酸化导致 GluN1-GluN2B 受体到突触膜的胞吐作用。Pyk2 的活性通过几个关键酪氨酸位点的磷酸化来调节，包括 Tyr（402）。在这项研究中，我们报告 Pyk2 是纹状体丰富的蛋白酪氨酸磷酸酶（STEP）的底物。STEP 结合并使 Pyk2 在 Tyr（402）去磷酸化。STEP KO 小鼠显示 Pyk2 在 Tyr（402）和 Pyk2 底物 paxillin 和 ASAP1 的磷酸化增强。功能研究表明，STEP 在皮质切片的 KCl 去极化后拮抗 Pyk2 的激活，并阻止 Pyk2 向突触后密度的易位，这是 Pyk2 激活和功能所必需的关键步骤。这是首次鉴定 Pyk2 为 STEP 底物的研究。
