MECHANISMS OF TRANSCRIPTIONAL REGULATION AND NEURAL GENE-EXPRESSION

Gene transcription is governed by a set of basal transcription machine ries and gene-specific factors. Eukaryotic RNA polymerases alone can n ot direct specific transcription, but need associated factors, namely general transcription factors (GTFs). The basal transcription machiner ies composed of RNA polymerase and GTFs bind to a promoter and govern efficient and correct transcription for constitutive gene expression. Protein-coding genes are transcribed by RNA polymerase (Pol) II wherea s Pol I and Pol III synthesize ribosomal RNA and various small RNAs, r espectively. Enhancer is another class of cis-element for Pol II to wh ich transcription regulatory factors bind. Those factors are involved in inducible, repressive, and tissue-specific gene expressions via bin ding to their target sequences. Regulatory factors have multiple struc tural motifs and interact with basal machineries directly or indirectl y (using mediators) in addition to DNA. Many transcription factors are known to regulate nervous system-specific gene expression, which incl ude bHTH, bHLH, basic leucine zipper, and zinc finger factors and pror ine-rich activators. These factors, some of which belong to a neural s ilencer factor, play roles in neural development, establishment of mem ory and learning, and expression of nervous system-specific proteins. Copyright (C) 1996 Elsevier Science Ltd