New insights for understanding the transcription-coupled repair pathway.

Transcription-coupled repair (TCR) is a sub-pathway of nucleotide excision repair (NER) able to remove bulky DNA lesions located on the transcribed strands of active genes more rapidly than those located on the non-transcribed genomic DNA. Two recently published reports try to dissect the molecular mechanisms of TCR using simplified in vitro assays. A third report shows in vivo data that confirmed the in vitro ones and extends them to the role of other TCR factors such as those involved in chromatin remodeling. These approaches shed light on the interplay between stalled RNA polymerase II and NER factors necessary for efficient repair. Because severe diseases, such as Cockayne syndrome, are associated with defects or mutations in proteins required for transcription-coupled nucleotide excision repair, complete understanding of this pathway should allow us to understand this disease better and eventually to propose adequate therapies.