title: Transcriptional regulatory events initiated by Ascl1 and Neurog2 during neuronal differentiation of P19 embryonic carcinoma cells.
abstract: As members of the proneural basic-helix-loop-helix (bHLH) family of transcription factors, Ascl1 and Neurog2 direct the differentiation of specific populations of neurons at various times and locations within the developing nervous system. In order to characterize the mechanisms employed by these two bHLH factors, we generated stable, doxycycline-inducible lines of P19 embryonic carcinoma cells that express comparable levels of Ascl1 and Neurog2. Upon induction, both Ascl1 and Neurog2 directed morphological and immunocytochemical changes consistent with initiation of neuronal differentiation. Comparison of Ascl1- and Neurog2-regulated genes by microarray analyses showed both shared and distinct transcriptional changes for each bHLH protein. In both Ascl1- and Neurog2-differentiating cells, repression of Oct4 mRNA levels was accompanied by increased Oct4 promoter methylation. However, DNA demethylation was not detected for genes induced by either bHLH protein. Neurog2-induced genes included glutamatergic marker genes while Ascl1-induced genes included GABAergic marker genes. The Neurog2-specific induction of a gene encoding a protein phosphatase inhibitor, Ppp1r14a, was dependent on distinct, canonical E-box sequences within the Ppp1r14a promoter and the nucleotide sequences within these E-boxes were partially responsible for Neurog2-specific regulation. Our results illustrate multiple novel mechanisms by which Ascl1 and Neurog2 regulate gene repression during neuronal differentiation in P19 cells.
authors.affiliation: Molecular and Behavioral Neuroscience Institute, University of Michigan, 109 Zina Pitcher Pl, Ann Arbor, MI, 48109-2200, USA.
authors.forename: Holly S
authors.initials: HS
authors.lastname: Huang
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Redmond
authors.forename: Ginger M
authors.initials: GM
authors.lastname: Kubish
authors.forename: Shweta
authors.initials: S
authors.lastname: Gupta
authors.forename: Robert C
authors.initials: RC
authors.lastname: Thompson
authors.forename: David L
authors.initials: DL
authors.lastname: Turner
authors.forename: Michael D
authors.initials: MD
authors.lastname: Uhler
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D054278:Embryonal Carcinoma Stem Cells / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D055495:Neurogenesis; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D050814:Octamer Transcription Factor-3; D010750:Phosphoproteins; C499317:Ascl1 protein, mouse; C102938:Neurog2 protein, mouse; C494174:Pou5f1 protein, mouse; C491520:Ppp1r14a protein, mouse