sq-23377 and Bipolar-Disorder

Mutations that reduce expression or give rise to a Thr85Ser (T85S) mutation of Ca(2+)-CaM-dependent protein kinase kinase-2 (CaMKK2) have been implicated in behavioural disorders such as anxiety, bipolar and schizophrenia in humans. Here we report that Thr85 is an autophosphorylation site that endows CaMKK2 with a molecular memory that enables sustained autonomous activation following an initial, transient Ca(2+) signal. Conversely, autophosphorylation of Ser85 in the T85S mutant fails to generate autonomous activity but instead causes a partial loss of CaMKK2 activity. The loss of autonomous activity in the mutant can be rescued by blocking glycogen synthase kinase-3 (GSK3) phosphorylation of CaMKK2 with the anti-mania drug lithium. Furthermore, CaMKK2 null mice representing a loss of function model the human behavioural phenotypes, displaying anxiety and manic-like behavioural disturbances. Our data provide a novel insight into CaMKK2 regulation and its perturbation by a mutation associated with behavioural disorders.

Topics: Amino Acid Sequence; Animals; Anxiety; Bipolar Disorder; Calcium; Calcium-Calmodulin-Dependent Protein Kinase Kinase; Cell Line; Chlorocebus aethiops; COS Cells; Glycogen Synthase Kinase 3; Humans; Ionomycin; Lithium Chloride; Maze Learning; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutation; Phosphorylation; Reflex, Startle; Sequence Alignment

Lithium, carbamazepine and sodium valproate are mood stabilizers used in the treatment of bipolar disorder, and although their mechanisms of action remain unknown, signal transduction systems and the associated modulation of gene expression may constitute significant actions. We examined if acute or chronic treatments with these agents modulated the activation of the AP-1 transcription factor or the increased intracellular calcium levels in human neuroblastoma SH-SY5Y cells caused by stimulation with carbachol. AP-1 activation stimulated by carbachol was reduced by pretreatment for 1 h, 24 h or 7 days with 1 mM lithium by 15%, 37%, and 60%, respectively, and with 0.05 mM carbamazepine by 3%, 21%, and 46%, respectively, but not by pretreatment with 0.5 mM sodium valproate. AP-1 DNA binding activity stimulated by carbachol or by phorbol ester-induced activation of protein kinase C was inhibited by the protein kinase C inhibitor Ro31-8220, but phorbol ester-stimulated AP-1 activation was unaltered by 7-day pretreatments with lithium or carbamazepine. Activation of AP-1 by carbachol was dependent on calcium, as it was inhibited by treatment with the extracellular calcium chelator EGTA, the intracellular calcium chelator BAPTA-AM, and the calcium/calmodulin kinase II inhibitor KN62. Pretreatment for 7 days with lithium or carbamazepine had no significant effect on carbachol-stimulated increases in intracellular calcium levels, but reduced the stimulation of AP-1 by the calcium ionophore ionomycin by 30% to 40%. Thus, chronic treatment with the antibipolar agents lithium and carbamazepine attenuates carbachol-stimulated AP-1 DNA binding activity, and these agents preferentially inhibit signaling cascades activated by the calcium rather than the protein kinase C arm of the phosphoinositide signaling pathway.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Antipsychotic Agents; Bipolar Disorder; Calcium; Calcium Signaling; Carbachol; Carbamazepine; Chelating Agents; DNA; Dose-Response Relationship, Drug; Edetic Acid; Egtazic Acid; Gene Expression Regulation; Humans; Indoles; Ionomycin; Ionophores; Lithium; Muscarinic Agonists; Nerve Tissue Proteins; Neuroblastoma; Neurons; Phosphatidylinositols; Protein Binding; Protein Kinase C; Signal Transduction; Tetradecanoylphorbol Acetate; Transcription Factor AP-1; Tumor Cells, Cultured; Valproic Acid