Diversified transcription initiation complexes expand promoter selectivity and tissue-specific gene expression
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3204, USA
This extract was created in the absence of an abstract.
Transcription initiation is a key regulatory step in the control of gene expression. Formation of a preinitiation complex at the right time and at the right promoter is a prerequisite to executing the correct programs of mRNA synthesis. This involves the interplay of many transcription factors and a combinatorial array of cis-regulatory DNA elements. Recent findings suggest that metazoan organisms have evolved specialized transcription initiation complexes and promoter-selectivity modules that direct coordinated regulation of functionally related gene networks. Here, we summarize corroborating evidence for a highly diversified core transcription machinery directing cell type-specific and gene-selective transcription.
In multicellular organisms elaborate mechanisms have evolved to control the spatial and temporal patterns of transcription during growth, differentiation, and development. Transcriptional activation, one of the fundamental means of regulating gene expression in eukaryotes, is governed by an interconnected ensemble of multisubunit transcription factor complexes (Fig. 1; Lemon and Tjian 2000; Narlikar et al. 2002; Orphanides and Reinberg 2002). To assure the proper assembly of the transcription machinery, the components of the core transcriptional apparatus and the chromatin DNA template are subject to regulation. For instance, a variety of covalent histone and DNA modifications can influence whether a chromatin template is programmed to be transcriptionally active or silent (Strahl and Allis 2000; Berger 2002; Geiman and Robertson 2002). Also, numerous chromatin remodeling/nucleosome mobilizing activities catalyze the ATP-dependent deposition, removal, or sliding of nucleosomes to generate DNA templates that are accessible to the transcription machinery (Becker and Horz 2002). An enormous family of DNA sequence-specific transcriptional activators working in concert with various coregulatory factors drive the formation of active transcription initiation complexes (Lemon and Tjian 2000; Malik and Roeder 2000; Naar et al. 2001). It now seems clear that this highly regulated and coordinated assembly of active transcription …
