Study of transcriptional regulation of Arabidopsis ASF1 histone chaperones by E2F factors

LARIO, L; CASATI, P; SPAMPINATO, C; RAMIREZ-PARRA, E; GUTIERREZ, C

Tucumán. Argentina

Congreso; • XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2009

Sociedad Argentina de Investigación Bioquímica (SAIB)

Study of transcriptional regulation of Arabidospis ASF1 histone chaperones by E2F factors Lario a, L.; Casati a, P.; Spampinato a, C.; Ramirez-Parra b, E.; Gutierrez b, C.  aCEFOBI, Univ. Nac. Rosario, Argentina; b CBMSO Centro de Biología Molecular “Severo Ochoa”. Madrid, Spain. ASF1 (anti-silencing function 1) is a conserved H3-H4 histone-chaperone first identified in yeast, that assembles or disassembles chromating during transcription, replication and repair. In the Arabidopsis genome are presents two homologs of asf1: asf1a and asf1b, but their roles in plants have not been studied yet. Here, we show that these genes are target of E2F factors, which regulate the transcription of genes required for cell cycle progression and DNA replication. By bioinformatic tools, we have identified the E2F DNA-binding sites in asf1a and asf1b promoters. Through Electrophoretic mobility shift assays (EMSA), we have found that Arabidopsis E2F proteins, can bind to these E2F sites in vitro. This was confirmed by chromatin immunoprecipitation (ChIP) studies, revealing that E2F can bind directly to the asf1a and asf1b promoters in vivo and regulate their expression. Furthermore, transgenic Arabidopsis plants overexpressing various E2F proteins (such as E2Fa, E2Fb, E2Fd and E2Ff), in all cases, show increased asf1b expression. In contrast, plants overexpressing the repressor E2Fc or a dominant negative version of DP, the dimerization partner of Arabidopsis E2Fa, E2Fb and E2Fc proteins, and required for E2F activity, show decreased asf1a and asf1b expression. The results demonstrate that members of the E2F family regulate asf1a and asf1b gene expression