Two types of DNA lesions differentially affect alternative splicing: a new role for NER factors

NICOLÁS NIETO MORENO; LUCIANA GIONO; ADRIÁN CAMBINDO BOTTO; ALBERTO R. KORNBLIHTT; MANUEL J. MUÑOZ

Buenos Aires

Conferencia; EMBO-CONICET Conference: Ubiquitin & UBLs. At the crossroads from chromatin to protein; 2014

EMBO-CONICET

The UV radiation that reaches the Earth?s surface can damage cellular components such as DNA, RNA, proteins and lipids and is, therefore, the most prominent and ubiquitous carcinogen in our natural environment. Keratinocytes, the major cell type of our skin, are regularly exposed to UV radiation. We have shown that UV irradiation slows down transcriptional elongation and affects alternative splicing (AS) of several genes, some of which are key for survival/apoptosis decisions. Now we have demonstrated that introduction of in vitro damaged DNA into skin cells is sufficient to mimic the UV effect on AS. Moreover, we have found that the main types of UV-induced DNA lesions, cyclobutane pyrimidine dimers (CPDs) and 6-4 pyrimidine-pyrimidones [(6-4)PPs], differentially affect AS patterns. The major pathway that deals with UV-induced DNA damage is Nucleotide Excision Repair (NER). NER is initiated by two distinct DNA damage-sensing mechanisms: Transcription Coupled Repair (TCR) and Global Genome Repair (GGR). Unlike GGR, TCR depends on RNA polymerase II transcription. We have ruled out TCR and showed that the UV effect depends on the xeroderma pigmentosum proteins typically needed in GGR: using siRNA-mediated knockdown we have demonstrated that XPE are involved in the signaling from the DNA lesion to the transcriptional and splicing machinery, which underscores a new role for NER in skin cells.