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Cholinergic Stimulation of Early Growth Response‐1 DNA Binding Activity Requires Protein Kinase C and Mitogen‐Activated Protein KInase Kinase Activation and Is Inhibited by Sodium Valporate in SH‐SY5y Cells
Author(s) -
Grimes Carol A.,
Jope Richard S.
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.0731384.x
Subject(s) - carbachol , protein kinase a , protein kinase c , ask1 , biology , chemistry , kinase , mitogen activated protein kinase kinase , microbiology and biotechnology , endocrinology , stimulation
: Activation of muscarinic receptors in human neuroblastoma SH‐SY5Y cells with carbachol stimulated a rapid and large increase in early growth response‐1 (Egr‐1, also called zif268 and NGF1‐A) protein levels and DNA binding activity. Egr‐1 DNA binding activity was stimulated within 15 min of treatment with carbachol and maintained a maximum 20‐fold increase over basal between 1 and 2 h after treatment, and the EC 50 was ~ μ M carbachol. Carbachol‐stimulated Egr‐1 DNA binding activity was dependent on protein kinase C, as it was potently inhibited by GF109203× (IC 50 ~0.1 m M ) and was reduced by 85 ± 5% by down‐regulation of protein kinase C. Inhibitors of increases in intracellular calcium levels reduced carbachol‐induced Egr‐1 DNA binding activity by 25‐35%. Carbachol‐stimulated activation of Egr‐1 was reduced 35% by genistein, a tyrosine kinase inhibitor, and 60% by PD098059, an inhibitor of mitogen‐activated protein kinase kinases 1/2 (MEK1/2) that activates extracellular‐regulated kinases 1/2 (ERK1/2). A novel inhibitory action was caused by chronic (7‐day) administration of sodium valproate but not by two other bipolar disorder therapeutic agents, lithium and carbamazepine. Valproate treatment reduced carbachol‐stimulated Egr‐1 DNA binding activity by 60% but did not alter carbachol‐induced activation of ERK1/2 or p38 or increases in Egr‐1 protein levels. These results reveal that muscarinic receptors activate Egr‐1 through a signaling cascade primarily encompassing protein kinase C, MEK1/2, and ERK1/2 and that valproate substantially inhibits Egr‐1 DNA binding activity stimulated by carbachol or protein kinase C.