Abstract
Fanconi anemia (FA) is a rare hereditary disorder characterized by malignant tumors, chromosomal instability, and an extreme sensitivity to DNA cross-linkers. Altogether 15 FA genes constitute the FA pathway, which is thought to stabilize the stalled replication forks. DNA damage and replication stress trigger the monoubiquitination of the key FA proteins FANCD2 and FANCI, which is mediated by a multi-subunit E3 ubiquitin ligase (called the FA core complex). Although monoubiquitination of FANCD2 is critical for DNA crosslink repair, how FANCD2 functions in the DNA damage response is still poorly understood. In this study, we tried to identify FANCD2/FANCI-associated proteins. We have purified FANCD2 or FANCI complex by two-step immunoprecipitation from HeLa S3 cell stably expressing HA-FLAG-tagged FANCD2 or FANCI that was challenged with the replication inhibitor hydroxyurea, and associated proteins were identified by mass spectrometry. The FANCD2/FANCI complex contained recently reported FAN1 nuclease, the FA core complex components, and novel interacting proteins that may have an important role in the FA pathway. We will discuss functional implications of these findings.
