Role of Mediator complex in DNA damage responses.

PAULA CASATI; MARÍA LORENA FALCONE-FERREYRA; MARISOL GIUSTOZZI

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

In Eukaryotes, the multiprotein Mediator complex regulates transcription by participating in RNA polymerase II assembly, RNA processing, as well as by modulating chromatin architecture. Moreover, recent reports have shown that Mediator plays an important role by connecting transcription with DNA repair in humans and yeast. In Arabidopsis thaliana, mediator is composed by 34 subunits and acts as a signal integrator. On the other hand, depletion of the stratospheric ozone layer has increased ultraviolet-B radiation (UV-B) level at the earth´s surface, causing DNA damage, primarily cyclobutane pyrimidine dimers. These lesions affect DNA replication and transcription, and as a consequence leaf growth is inhibits. The objective of this work is to investigate the participation of Mediator in DNA damage responses by UV-B radiation in plants, using as a model A. thaliana plants. For this purpose, we analyzed the effect of UV-B in Arabidopsis mutants in the Mediator complex subunit 17, mutations of its orthologues in yeast and humans are impaired in transcription coupled DNA damage repair. Our results show that med17 mutants show increased DNA damage after UV-B exposure, and are also deficient in different DNA damage responses. Together, our results suggest that MED17 has an important role during DNA damage responses induced by UV-B radiation in Arabidopsis.