title: Regulation of ERK Kinase by MEK1 Kinase Inhibition in the Brain.
abstract: Metabotropic (slow) and ionotropic (fast) neurotransmission are integrated by intracellular signal transduction mechanisms involving protein phosphorylation/dephosphorylation to achieve experience-dependent alterations in brain circuitry. ERK is an important effector of both slow and fast forms of neurotransmission and has been implicated in normal brain function and CNS diseases. Here we characterize phosphorylation of the ERK-activating protein kinase MEK1 by Cdk5, ERK, and Cdk1 in vitro in intact mouse brain tissue and in the context of an animal behavioral paradigm of stress. Cdk5 only phosphorylates Thr-292, whereas ERK and Cdk1 phosphorylate both Thr-292 and Thr-286 MEK1. These sites interact in a kinase-specific manner and inhibit the ability of MEK1 to activate ERK. Thr-292 and Thr-286 MEK1 are phosphorylated in most mouse brain regions to stoichiometries of ~5% or less. Phosphorylation of Thr-292 MEK1 is regulated by cAMP-dependent signaling in mouse striatum in a manner consistent with negative feedback inhibition in response to ERK activation. Protein phosphatase 1 and 2A contribute to the maintenance of the basal phosphorylation state of both Thr-292 and Thr-286 MEK1 and that of ERK. Activation of the NMDA class of ionotropic glutamate receptors reduces inhibitory MEK1 phosphorylation, whereas forced swim, a paradigm of acute stress, attenuates Thr-292 MEK1 phosphorylation. Together, the data indicate that these inhibitory MEK1 sites phosphorylated by Cdk5 and ERK1 serve as mechanistic points of convergence for the regulation of ERK signaling by both slow and fast neurotransmission.
authors.affiliation: From the Departments of Psychiatry and.
authors.forename: Tara C
authors.initials: TC
authors.lastname: Tassin
authors.affiliation: the Department of Neurology, The Johns Hopkins Hospital, Baltimore, Maryland 21287, and.
authors.forename: David R
authors.initials: DR
authors.lastname: Benavides
authors.affiliation: From the Departments of Psychiatry and.
authors.forename: Florian
authors.initials: F
authors.lastname: Plattner
authors.affiliation: the Department of Pharmacology, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Nishi
authors.affiliation: From the Departments of Psychiatry and Neurology and Neurotherapeutics and Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, james.bibb@utsouthwestern.edu.
authors.forename: James A
authors.initials: JA
authors.lastname: Bibb
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D051360:Cyclin-Dependent Kinase 5 / Q000235:genetics / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D051360:Cyclin-Dependent Kinase 5; D016203:CDC2 Protein Kinase; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1
keywords: Cdk5; ERK; MAPK; MEK1; NMDA receptor (NMDAR); cyclin-dependent kinase (CDK); depression; dopamine; phosphorylation; striatum