c-Jun Targets Cockayne Syndrome protein B to Specific Genomic Region for Transcription Regulation

Cockayne syndrome is an inherited premature aging syndrome associated with developmental and neurological disorders. Mutations in the genomic locus encoding CSB are associated with 80% Cockayne syndrome cases. Transcription profiling assays reveal the association of mis-regulation of gene expression with Cockayne syndrome, highlighting the importance of CSB in transcription regulation. However, many questions remain unanswered as how CSB regulates transcription. In this study, we dissect the mechanisms by which CSB regulates transcription during normal growth. By anti-CSB chromatin immunoprecipitation followed by deep sequencing, we found CSB is enriched at genomic regions containing TGASTCA motifs, to which the immediate early gene product C-Jun binds specifically. We further demonstrate that c-Jun co-immunoprecipitates with CSB. In addition, the targeting of CSB to genomic region containing TGASTCA motifs was drastically reduced in cells treated c-Jun shRNA. Reverse transcription followed by quantitative PCR indicates that CSB can regulate gene expression nearby its binding sites, both in activation and repression. The remodeling defective CSB∆N1 mutant is also targeted to TGASTCA motifs, but cannot always substitute CSB function in transcription regulating, suggesting the importance of remodeling by CSB in transcription regulation. Notably, the Cockayne syndrome related mutation encoding protein CSBR670W, which is defective in ATP hydrolysis but is targeted to TGASTCA motifs efficiently, indicating that ATP hydrolysis is dispensable for c-Jun mediated CSB targeting, in sharp contrast to the ATP-dependent targeting mechanism by which CSB is relocated to DNA lesion stalled transcription. Together, these results reveal a second CSB targeting mechanism in which DNA sequence specific transcription factor c-Jun targets CSB to specific genomic region and regulate gene expression. Genomic localization of CSB and remodeling deficient CSB∆N1