Papers In Press, published online ahead of print February 8, 2008
J. Biol. Chem, 10.1074/jbc.M709076200
Submitted on November 6, 2007
Revised on February 5, 2008
Accepted on February 8, 2008
Tip60 is required for DNA interstrand crosslink repair in the Fanconi anemia pathway
James Hejna, Megan Holtorf, Jennie Hines, Lauren Mathewson, Aaron Hemphill, Muhsen Al-Dhalimy, Susan B. Olson, and Robb E. Moses
Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97236
Corresponding Author: mosesr{at}ohsu.edu
The disease Fanconi anemia is a genome instability syndrome characterized by cellular sensitivity to DNA interstrand crosslinking agents, manifest by decreased cellular survival and chromosomal aberrations after such treatment. There are at least thirteen proteins acting in the pathway, with the FANCD2 protein apparently functioning as a late term effecter in the maintenance of genome stability. We find that the chromatin remodeling protein, Tip60, interacts directly with the FANCD2 protein in a yeast two-hybrid system. This interaction has been confirmed by co-immunoprecipitation and co-localization using both endogenous and epitope-tagged FANCD2 and Tip60 from human cells. The observation of decreased cellular survival after exposure to mitomycin C in normal fibroblasts depleted for Tip60 indicates a direct function in interstrand crosslink repair. The coincident function of Tip60 and FANCD2 in one pathway is supported by the finding that depletion of Tip60 in Fanconi anemia cells does not increase sensitivity to DNA crosslinks. However, depletion of Tip60 did not reduce monoubiquitination of FANCD2 or its localization to nuclear foci following DNA damage. The observations indicate that Fanconi anemia proteins act in concert with chromatin remodeling functions to maintain genome stability after DNA crosslink damage.