Genome-wide chromatin remodeling modulates the Alu heat shock response

During heat shock recovery in Hela cells, the level of Alu RNA transiently increases with kinetics that approximately parallel the transient expressio n of heat shock protein mRNAs. Coincidentally, there is a transient increas e in the accessibility of Alu chromatin to restriction enzyme cleavage sugg esting that an opening and re-closing of chromatin regulates the Alu stress response. Similar changes occur in alpha satellite and LINE1 chromatin sho wing that heat shock induces a genome-wide remodeling of chromatin structur e which is independent of transcription. The increased accessibility of res triction sites within these repetitive sequences is inconsistent with a sim ple lengthening of the nucleosome linker region but instead suggests a scra mbling of nucleosome positions. Chromatin structure and its dynamics accoun t for many of the principal features of SINE transcriptional regulation pot entially providing a functional rationale for the dispersion and high copy number of SINEs. (C) 2001 Elsevier Science B.V. All rights reserved.