Regulating large chromatin domains

The thymocyte-specific special AT-rich sequence binding 1 (SATB1) protein binds to base unpairing regions (BUR) within matrix attachment regions and assembles a SATB1 network structure that can regulate gene expression over relatively large distances. In the October 10 Nature, Dag Yasui and colleagues describe biochemical analysis of SATB1 within BUR-binding complexes (Nature, 419:641-645, October 10, 2002).

Yasui et al. analyzed extracts from the thymi of normal and knockout (SATB1^-/-) mice and found that components of the NURD, CHRAC and ACF chromatin remodeling complexes co-purified with SATB1. Immunoprecipitation analysis showed that SATB1 recruits histone deacetylases and remodeling complexes to generate repression at the IL-2Ralpha ('inteleukin-2 receptor alpha') locus. Changes in nucleosome positioning in the absence of SATB1 could be observed up to 8 kb away, suggesting that mechanisms of this sort play a general a role in global gene regulation.