Regulation of the Fanconi anemia pathway by monoubiquitination

Fanconi anemia (FA) is an autosomal recessive cancer susceptibility syndrome characterized by multiple congenital anomalies, bone marrow failure, and cellular sensitivity to mitomycin C (MMC). To date, six FA genes have been cloned, and the encoded proteins function in a novel pathway. The FA pathway is required for the normal cellular response to DNA damage. Following DNA damage, the pathway is activated, leading to monoubiquitination of the FA protein, FANCD2, and its targeting to subnuclear foci. Disruption of the FA pathway results in the absence of FANCD2 nuclear foci, leading to the cellular and clinical abnormalities of FA. Here, we review the recent studies describing the regulated monoubiquitination of the FANCD2 protein and discuss the interaction of the FA pathway with other DNA damage response pathways.