© 2002 Elsevier Science
Genomic DNA is wrapped around histone octamers to provide nucleosomes that are further compacted in chromatin fibers. To up-regulate a gene (a), the activator binds to a specific sequence and recruits various cellular machines that permit RNA polymerase and its associated proteins to bind and transcribe. During transcriptional repression (b), the repressor binds to a specific DNA site and recruits protein complexes that modify the histones and thereby compact the DNA. (Reprinted with permission from A. Ansari, Curr Opin Chem Biol, 6:765–72, 2002.)
Scientists have long understood that changes in gene expression can lead to disease. But the details of the relationship between these changes and the diseases themselves remain sketchy. "What we'd like to have are molecules that control gene expression that we could use to probe those relationships," says Anna Mapp, a chemist at University of Michigan in Ann Arbor.
Scientists such as Mapp ...
