A very interesting story about the way of talented people towards novel discoveries and nobel prises. Their experiments laid foundation to textbook examples of transcriptional regulation. Two reviews, one about transcriptional repressors and another about enhancers, brief latest findings of the field.
Curr Biol. 2010 Sep 14;20(17):R718-23.
Jacob and Monod: from operons to EvoDevo.
PMID: 20833316
Curr Biol. 2010 Sep 14;20(17):R764-71.
Transcriptional repression: conserved and evolved features.
Payankaulam S, Li LM, Arnosti DN.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48910, USA.
Abstract
The regulation of gene expression by transcriptional repression is an ancient and conserved mechanism that manifests itself in diverse ways. Here we summarize conserved pathways for transcriptional repression prevalent throughout all forms of life, as well as indirect mechanisms that appear to have originated in eukaryotes, consistent with the unique chromatin environment of eukaryotic genes. The direct interactions between transcriptional repressors and the core transcriptional machinery in bacteria and archaea are sufficient to generate a sophisticated suite of mechanisms that provide flexible control. These direct interactions contrast with the activity of corepressors, which provide an additional regulatory control in eukaryotes. Their modulation of chromatin structure represents an indirect pathway to downregulate transcription, and their diversity and modulation provide additional complexity suited to the requirements of elaborate eukaryotic repression patterns. New findings indicate that corepressors are not necessarily restricted to generating a single stereotypic output, but can rather exhibit diverse functional responses depending on the context in which they are recruited, providing a hitherto unsuspected additional source of diversity in transcriptional control. Mechanisms within eukaryotes appear to be highly conserved, with novel aspects chiefly represented by addition of lineage-specific corepressor scaffolds that provide additional opportunities for recruiting the same core machinery.
Copyright © 2010 Elsevier Ltd. All rights reserved.
PMID: 20833321
Curr Biol. 2010 Sep 14;20(17):R754-63.
Transcriptional enhancers in animal development and evolution.
Department of Molecular and Cell Biology, University of California-Berkeley, CA 94720, USA. mlevine@berkeley.edu
Abstract
Regulatory DNAs serve as templates to bring weakly interacting transcription factors into close proximity so they can work synergistically to switch genes on and off in time and space. Most of these regulatory DNAs are enhancers that can work over long distances–a million base pairs or more in mammals–to control gene expression. Critical enhancers are sometimes even found within the introns of neighboring genes. This review summarizes well-defined examples of enhancers controlling key processes in animal development. Potential mechanisms of transcriptional synergy are discussed with regard to enhancer structure and contemporary ChIP-sequencing assays, whereby just a small fraction of the observed binding sites represent bona fide regulatory DNAs. Finally, there is a discussion of how enhancer evolution can produce novelty in animal morphology and of the prospects for reconstructing transitions in animal evolution by introducing derived enhancers in basal ancestors.
Copyright © 2010 Elsevier Ltd. All rights reserved.
PMID: 20833320
