The Conserved PBAF Nucleosome-Remodeling Complex Mediates the Response to Stress in Caenorhabditis elegans

Abstract

ABSTRACT To adapt to stress, cells must undergo major changes in their gene expression profiles. We have previously described a largely uncharacterized stress response pathway in Caenorhabditis elegans that acts through an evolutionarily conserved motif, termed ESRE, for e thanol and s tress r esponse e lement. We characterize here the requirements for ESRE gene expression and show that the ESRE network is regulated by a conserved SWI/SNF family nucleosome remodeling complex termed PBAF. Depletion of PBAF subunits SWSN-7/BAF200 and PBRM-1/BAF180 results in decreased expression of ESRE genes and increased sensitivity to thermal stress. When overexpressed, SWSN-7/BAF200 and PBRM-1/BAF180 led to increased ESRE transcription, enhanced thermotolerance, and induction of a nuclear ESRE-binding activity. Our data support a model in which PBAF is recruited by an ESRE-binding protein to genomic ESRE sites. We also show that the closely related SWI/SNF complex, BAF, which regulates stress induction through DAF-16/FOXO, does not contribute to ESRE gene expression or bind directly to ESRE sites. To our knowledge, this is the first report demonstrating direct and specific regulation of a stress response network by the PBAF nucleosome-remodeling complex in vivo in metazoa. In addition, we show that PBAF cooperates with the histone demethylase, JMJC-1/NO66, to promote expression of ESRE genes following stress.