Diversified transcription initiation complexes expand promoter selectivity and tissue-specific gene expression

摘要: Transcription initiation is a key regulatory step in the control of gene expression. Formation preinitiation complex at right time and promoter prerequisite to executing correct programs mRNA synthesis. This involves interplay many transcription factors combinatorial array cis-regulatory DNA elements. Recent findings suggest that metazoan organisms have evolved specialized complexes promoter-selectivity modules direct coordinated regulation functionally related networks. Here, we summarize corroborating evidence for highly diversified core machinery directing cell type-specific gene-selective transcription. In multicellular elaborate mechanisms spatial temporal patterns during growth, differentiation, development. Transcriptional activation, one fundamental means regulating expression eukaryotes, governed by an interconnected ensemble multisubunit factor (Fig. 1; Lemon Tjian 2000; Narlikar et al. 2002; Orphanides Reinberg 2002). To assure proper assembly machinery, components transcriptional apparatus chromatin template are subject regulation. For instance, variety covalent histone modifications can influence whether programmed be transcriptionally active or silent (Strahl Allis Berger Geiman Robertson Also, numerous remodeling/nucleosome mobilizing activities catalyze ATP-dependent deposition, removal, sliding nucleosomes generate templates accessible (Becker Horz An enormous family sequence-specific activators working concert with various coregulatory drive formation (Lemon Malik Roeder Naar 2001). It now seems clear this regulated requires large number factors, multiple elements, remodeling modifying properly position (PIC) start site RNA synthesis (Burley 1996; Fig. 1). Until recently, general makes up PIC was thought largely invariant when compared among different types within organism. Although tissue-specific been described genes, most these enhancer-binding factors. However, contrary expectations, several studies identified machinery. Subsequently, increasing homologs basal organisms, including additional members TATA boxbinding protein (TBP) such as TBP-related (TRFs) well TBP-associated (TAFs). apparent mechanism accommodate more Intriguingly, subunits TFIID. central component harbors directly involved recognizing binding elements box, Initiator (Inr), downstream element (DPE). These metazoans promoter-selective modules, which might serve eukaryotic (Gross 1998; Losick 1998). review, will some recent advances our understanding how mediate proCorresponding author. EMAIL jmlim@uclink4.berkeley.edu; FAX (510) 643-9547. Article publication http://www.genesdev.org/cgi/doi/10.1101/ gad.1099903.