siRNA depletion of BRCA1, but not BRCA2, causes increased genome instability in Fanconi anemia cells.
BRCA1 and BRCA2 proteins act in repair of interstrand crosslinks (ICLs) and maintenance of genome stability and are known to be part of the Fanconi anemia (FA) pathway. We have investigated the role of the BRCA1 and BRCA2 genes in genome stability following ICL damage in normal and FA cells. To circumvent cell lethality of complete disruptions in BRCA1 or BRCA2, small inhibitory RNA (siRNA) was used to transiently deplete the expression of the proteins. Using chromosomal stability after ICL damage as the end point, we find that BRCA1 functions in more than just the FA pathway for genome maintenance, whereas BRCA2 appears to act predominantly in the FA pathway. Depletion of BRCA1 causes a marked decrease, although not a complete absence of, ubiquitination of FANCD2. In contrast to BRCA1, BRCA2 is not needed for normal ubiquitination of FANCD2 after DNA damage, a requirement for the FA pathway to function. Thus, BRCA2 is epistatic to FA genes for ICL repair, but not for damage-induced modification of FANCD2 and may act downstream form FANCD2.
Bruun
Donald
D
Department of Molecular and Medical Genetics, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, L-103, Portland, OR 97201-3098, USA.
Folias
Alexandra
A
Akkari
Yassmine
Y
Cox
Yumi
Y
Olson
Susan
S
Moses
Robb
R
D019313:BRCA1 Protein / Q000378:metabolism*; D024682:BRCA2 Protein / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins; D005199:Fanconi Anemia / Q000235:genetics* / Q000378:metabolism; D052236:Fanconi Anemia Complementation Group D2 Protein; D006801:Humans; D007621:Karyotyping; D009687:Nuclear Proteins / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology*; D029701:Saccharomyces cerevisiae Proteins
D019313:BRCA1 Protein; D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; C068394:DST1 protein, S cerevisiae; C499905:FANCD2 protein, human; D052236:Fanconi Anemia Complementation Group D2 Protein; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D029701:Saccharomyces cerevisiae Proteins