Striatal-enriched protein tyrosine phosphatase regulates the PTP?/Fyn signaling pathway.
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ABSTRACT: The tyrosine kinase Fyn has two regulatory tyrosine residues that when phosphorylated either activate (Tyr(420)) or inhibit (Tyr(531)) Fyn activity. Within the central nervous system, two protein tyrosine phosphatases (PTPs) target these regulatory tyrosines in Fyn. PTP? dephosphorylates Tyr(531) and activates Fyn, while STEP (STriatal-Enriched protein tyrosine Phosphatase) dephosphorylates Tyr(420) and inactivates Fyn. Thus, PTP? and STEP have opposing functions in the regulation of Fyn; however, whether there is cross talk between these two PTPs remains unclear. Here, we used molecular techniques in primary neuronal cultures and in vivo to demonstrate that STEP negatively regulates PTP? by directly dephosphorylating PTP? at its regulatory Tyr(789). Dephosphorylation of Tyr(789) prevents the translocation of PTP? to synaptic membranes, blocking its ability to interact with and activate Fyn. Genetic or pharmacologic reduction in STEP61 activity increased the phosphorylation of PTP? at Tyr(789), as well as increased translocation of PTP? to synaptic membranes. Activation of PTP? and Fyn and trafficking of GluN2B to synaptic membranes are necessary for ethanol (EtOH) intake behaviors in rodents. We tested the functional significance of STEP61 in this signaling pathway by EtOH administration to primary cultures as well as in vivo, and demonstrated that the inactivation of STEP61 by EtOH leads to the activation of PTP?, its translocation to synaptic membranes, and the activation of Fyn. These findings indicate a novel mechanism by which STEP61 regulates PTP? and suggest that STEP and PTP? coordinate the regulation of Fyn. STEP61 , PTP?, Fyn, and NMDA receptor (NMDAR) have been implicated in ethanol intake behaviors in the dorsomedial striatum (DMS) in rodents. Here, we report that PTP? is a novel substrate for STEP61. Upon ethanol exposure, STEP61 is phosphorylated and inactivated by protein kinase A (PKA) signaling in the DMS. As a result of STEP61 inhibition, there is an increase in the phosphorylation of PTP?, which translocates to lipid rafts and activates Fyn and subsequent NMDAR signaling. The results demonstrate a synergistic regulation of Fyn-NMDAR signaling by STEP61 and PTP?, which may contribute to the regulation of ethanol-related behaviors. NMDA, N-methyl-D-aspartate; PTP?, receptor-type protein tyrosine phosphatase alpha; STEP, STriatal-Enriched protein tyrosine Phosphatase.
SUBMITTER: Xu J
PROVIDER: S-EPMC4516628 | biostudies-literature | 2015 Aug
REPOSITORIES: biostudies-literature
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