BRCC36A is epistatic to BRCA1 in DNA crosslink repair and homologous recombination in Arabidopsis thaliana

Abstract

BRCA1 is a well-known tumor suppressor protein in mammals, involved in multiple cellular processes such as DNA repair, chromosome segregation and chromatin remodeling. Interestingly, homologs of BRCA1 and several of its complex partners are also found in plants. As the respective mutants are viable, in contrast to mammalian mutants, detailed analyses of their biological role is possible. Here we demonstrate that the model plant Arabidopsis thaliana harbors two homologs of the mammalian BRCA1 interaction partner BRCC36, AtBRCC36A and AtBRCC36B. Mutants of both genes as well as the double mutants are fully fertile and show no defects in development. We were able to show that mutation of one of the homologs, AtBRCC36A, leads to a severe defect in intra- and interchromosomal homologous recombination (HR). A HR defect is also apparent in Atbrca1 mutants. As the Atbrcc36a/Atbrca1 double mutant behaves like the single mutants of AtBRCA1 and AtBRCC36A both proteins seem to be involved in a common pathway in the regulation of HR. AtBRCC36 is also epistatic to AtBRCA1 in DNA crosslink repair. Upon genotoxic stress, AtBRCC36A is transferred into the nucleus.

Differential expression of lncRNAs during the HIV replication cycle: an underestimated layer in the HIV-host interplay

“…To date, only a few hundred lncRNAs are functionally validated4546. This limits the possibility to associate biological meaning based on existing data analysis tools that are available for mRNAs.…”

The landscape of long noncoding RNAs in the human transcriptome

“…The unprecedented breadth (6,503 samples) and depth (>43 Terabases of sequence) of our compendia enabled sensitive detection of robust transcription and specific filtration of background noise. The lncRNAs in our assembly (58,648 genes, often with multiple isoforms) far outnumber entries in current lncRNA databases (<16,000 genes), implying that reference transcript annotations may be fragmented or otherwise incomplete 11, 17, 43–46 . Moreover, our assembly indicates that the genomic diversity of lncRNAs eclipses coding transcripts (i.e., nearly 60,000 lncRNA genes versus approximately 30,000 protein coding genes), a disparity that may grow as additional diseases and cell types are sequenced and more lncRNAs are discovered.…”

Recent advances in the research for the homolog of breast cancer associated gene AtROW1 in higher plants

“…However, when challenged with the DNA cross-linking agent MMC, these two insertion mutants displayed a more sensitive phenotype as compared to wild-type seedlings (Han et al, 2008). Using a substrate that promotes DNA recombination, both Atrow1 and Atbrca1 mutants were shown to have defects in HR, which was especially prominent after the introduction of DSBs (Wu-Baer et al, 2003;Reidt et al, 2006;Block-Schmidt et al, 2010). To elucidate whether both these proteins act in the same DNA repair pathway, brca1-1 mutant was crossed with row1-2 to create a row1-2/brca1-1 double mutant to quantify the degree of MMC sensitivity, in comparison with both single mutants.…”

“…The homologs of all these animal DNA-damage repair factors that interact with the BRCT domain at the C terminus of BRCA1, are found in Arabidopsis (Table 1). AtBRCC36A and AtBRCC36B were found to share greater than 90% sequence identity with that of the human BRCC36 (Cooper et al, 2009;Block-Schmidt et al, 2010;Cantor and Xie, 2010). Homologs of MLH1 and MSH6, which is essential for formation of complex B in animals, was also identified in Arabidopsis (Ade et al, 1999;Jean et al, 1999;Greenberg et al, 2006).…”