Participation of chromatin remodeling proteins in UV-B responses

PAULA CASATI; LUCIANA D. LARIO; JULIA EMILIANI; MABEL CAMPI; VIRGINIA WALBOT; JULIA QÜESTA

Glasgow, UK

Congreso; Society for Experimental Biology Annual Main Meeting; 2009

Society for Experimental Biology

Participation of chromatin remodeling proteins in UV-B responses Paula Casati (UNR, Argentina), Luciana D. Lario (UNR, Argentina), Julia Emiliani (UNR, Argentina), Mabel Campi (UNR, Argentina), Virginia Walbot (Stanford University), Julia Qüesta (UNR, Argentina) Terrestrial life evolved after the ozone layer formed and could absorb most damaging UV-B in solar radiation. Chromatin remodeling in response to UV-B has been implicated in maize; in addition, several chromatin proteins are also UV-B regulated in Arabidopsis. Therefore, chromatin remodeling capacity appears to be a key process for effective responses to UV-B. ChIP assays were done to monitor chromatin status at several UV-B responsive genes: the promoter and transcribed regions in tolerant maize lines showed different chromatin protein association after UV-B than sensitive lines. Chromatin status was also investigated at terminal inverted repeats of the mutator transposon in maize, both in active and silencing states: reactivation by UV-B is accompanied by histone and DNA demethylation, correlating with an increase in MuRA and B transcripts. On the other hand, UV-B causes the formation of photoproducts in DNA, which affects the structural and dynamic properties of chromatin. To investigate the role of different chromatin remodeling proteins in DNA repair, Arabidopsis T-DNA mutants, and maize and Arabidopsis RNAi plants were analyzed. Several chromatin deficient plants (maize chc101, mbd101, sdg102 and nfc102; and Arabidopsis sdg26) showed increased UV-B-induced DNA damage; while others (Arabidopsis chc1) did not show significant differences with WT plants. On the contrary, ros1 mutants showed increased tolerance to DNA damage, suggesting that chromatin proteins regulate different aspects of DNA repair in plants. Our results indicate that chromatin remodeling is a key process in acclimation to UV-B and that plants deficient in this process are more sensitive to UV-B. Email Address for correspondence: casati@cefobi-conicet.gov.ar doi:10.1016/j.cbpa.2009.04.458