Striatal-enriched Protein-tyrosine Phosphatase (STEP) Regulates Pyk2 Kinase Activity

Jian Xu; Pradeep Kurup; Jason A. Bartos; Tommaso Patriarchi; Johannes W. Hell; Paul J. Lombroso

doi:10.1074/jbc.M112.368654

Striatal-enriched Protein-tyrosine Phosphatase (STEP) Regulates Pyk2 Kinase Activity*

From the ^‡Child Study Center and
Departments of ^‖Psychiatry and
^**Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06520,
^§Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242, and
^¶Department of Pharmacology, University of California, Davis, California 95615

↵1 To whom correspondence may be addressed: Child Study Center, Yale University School of Medicine, 230 South Frontage Rd., SHM I-269, New Haven, CT 06519. E-mail: jian.xu{at}yale.edu.
↵3 To whom correspondence may be addressed: Dept. of Pharmacology, School of Medicine, University of California at Davis, GBSF 3503, 451 East Health Sciences Dr., Davis, CA 95616. E-mail: jwhell{at}ucdavis.edu.

↵2 Present address: Dept. of Internal Medicine, Stanford University, Palo Alto, CA 94305.

Background: Proline-rich tyrosine kinase 2 (Pyk2) is implicated in synaptic plasticity; however, it remains unclear how Pyk2 is inactivated within neurons.

Results: Striatal-enriched protein-tyrosine phosphatase (STEP) directly binds to and dephosphorylates Pyk2 at Tyr⁴⁰².

Conclusion: STEP inactivates Pyk2 and its downstream signaling pathways.

Significance: These results identify an important regulatory mechanism for Pyk2 signaling that is critical for understanding the molecular mechanisms underlying synaptic plasticity.

Abstract

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 Tyr¹⁴⁷². 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 Tyr⁴⁰². In this study, we report that Pyk2 is a substrate of striatal-enriched protein-tyrosine phosphatase (STEP). STEP binds to and dephosphorylates Pyk2 at Tyr⁴⁰². STEP KO mice showed enhanced phosphorylation of Pyk2 at Tyr⁴⁰² 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.

Footnotes

↵* This work was supported, in whole or in part, by National Institutes of Health Grants MH052711 and MH091037 (to P. J. L.) and AG017502 (to J. W. H.).
↵ This article contains supplemental Figs. S1–S3.