ABSTRACT
The mood stabilizer valproic acid (VPA) decreases neural progenitor proliferation and promotes neurogenesis in the adult hippocampus. However, the effects of VPA on progenitor cells in the adult subventricular zone (SVZ) are not as well characterized. Here we report VPA blocks neurosphere formation and inhibits DNA synthesis in cultured NSCs from the SVZ of adult mice. Inhibition of DNA synthesis is associated with the up-regulation of the differentiation transcription factors Egr1 and Neurod1 and down-regulation of transcription factors associated with "stemness". Co-treatment of VPA with the mood stabilizer lithium antagonizes the anti-proliferative effects of VPA on adult NSCs and abolishes VPA activation of Egr1. Co-treatment of VPA with the MEK1/2 inhibitor PD980589 similarly abolishes Egr1 activation consistent with VPA activation and lithium antagonism of MEK-ERK signaling in adult NSCs. However, Western blot reveals VPA significantly suppresses ERK2 phosphorylation in adult NSCs grown in proliferating culture conditions and that lithium co-treatment does not attenuate this effect. Combined the data indicate VPA inhibition of adult NSC proliferation and activation of Egr1 by VPA, along with the antagonism of these effects by lithium, are the effects of cumulative changes in multiple signaling pathways and are not attributable to a common kinase target.
Subject(s)
Adult Stem Cells/drug effects , Anticonvulsants/pharmacology , Antimanic Agents/pharmacology , Lithium Chloride/pharmacology , Multipotent Stem Cells/drug effects , Neurogenesis/drug effects , Valproic Acid/pharmacology , Adult Stem Cells/cytology , Adult Stem Cells/metabolism , Animals , Basic Helix-Loop-Helix Transcription Factors/metabolism , CREB-Binding Protein/physiology , Cell Proliferation/drug effects , Cells, Cultured , Cerebral Ventricles/cytology , Cyclic AMP Response Element-Binding Protein/physiology , DNA/biosynthesis , Drug Antagonism , Early Growth Response Protein 1/genetics , Early Growth Response Protein 1/metabolism , Female , Histone Deacetylase Inhibitors/pharmacology , Male , Mice , Mice, Inbred C57BL , Mitogen-Activated Protein Kinase 1/physiology , Mitogen-Activated Protein Kinase 3/physiology , Multipotent Stem Cells/cytology , Multipotent Stem Cells/metabolism , Phosphorylation , Transcription, GeneticABSTRACT
Genetic analysis in mice has most commonly employed two general strategies: phenotypic screens for spontaneous or induced mutations and genotypic analysis using homologous recombination or gene trapping to produce deletion or insertion mutants. Here we use bacterial artificial chromosome (BAC)-mediated gene-dosage analysis in transgenic mice to reveal novel genetic functions that are not evident from conventional loss-of-function mutations. We demonstrate a role for the zinc-finger transcription factor Zipro1 (formerly Ru49 and Zfp38) in the proliferation of granule cell precursors in the developing cerebellum, and document the contribution of this process to the final stages of cerebellar morphogenesis. We also show that Zipro1 is expressed in skin, and increased Zipro1 dosage results in a hair-loss phenotype associated with increased epithelial cell proliferation and abnormal hair follicle development.
