Journal Article

FANCG promotes formation of a newly identified protein complex containing BRCA2, FANCD2 and XRCC3

Kupfer, G M, Wilson, J B, Hoatlin, M E, Hussain, S, Mathew, C G, Sung, P, Thompson, L H, Jones, N J, Yamamoto, K, Marriott, A S, Takata, M

2008

Overview

Fanconi anemia (FA) is a human disorder characterized by cancer susceptibility and cellular sensitivity to DNA crosslinks and other damages. Thirteen complementation groups and genes are identified, including BRCA2 , which is defective in the FA-D1 group. Eight of the FA proteins, including FANCG, participate in a nuclear core complex that is required for the monoubiquitylation of FANCD2 and FANCI. FANCD2, like FANCD1/BRCA2, is not part of the core complex, and we previously showed direct BRCA2–FANCD2 interaction using yeast two-hybrid analysis. We now show in human and hamster cells that expression of FANCG protein, but not the other core complex proteins, is required for co-precipitation of BRCA2 and FANCD2. We also show that phosphorylation of FANCG serine 7 is required for its co-precipitation with BRCA2, XRCC3 and FANCD2, as well as the direct interaction of BRCA2–FANCD2. These results argue that FANCG has a role independent of the FA core complex, and we propose that phosphorylation of serine 7 is the signalling event required for forming a discrete complex comprising FANCD1/BRCA2-FANCD2-FANCG-XRCC3 (D1-D2-G-X3). Cells that fail to express either phospho-Ser7-FANCG, or full length BRCA2 protein, lack the interactions amongst the four component proteins. A role for D1-D2-G-X3 in homologous recombination repair (HRR) is supported by our finding that FANCG and the RAD51-paralog XRCC3 are epistatic for sensitivity to DNA crosslinking compounds in DT40 chicken cells. Our findings further define the intricate interface between FANC and HRR proteins in maintaining chromosome stability.

• Publisher: Nature Publishing Group UK,Nature Publishing,Nature Publishing Group
• Subject: Anemia / Anemias. Hemoglobinopathies / Animals / Apoptosis / Ataxia Telangiectasia Mutated Proteins / Biological and medical sciences / BRCA2 protein / BRCA2 Protein - metabolism / Breast cancer / Cell Biology / Cell Cycle Proteins - physiology / Cell physiology / Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes / Cellular proteins / Chickens / CHO Cells / Chromosomal Instability / Chromosomes / Complementation / Cricetinae / Cricetulus / Deoxyribonucleic acid / Diagnosis / Diseases of red blood cells / DNA / DNA damage / DNA-Binding Proteins - metabolism / Epistasis / FANCG protein / Fanconi Anemia Complementation Group A Protein - metabolism / Fanconi Anemia Complementation Group D2 Protein - metabolism / Fanconi Anemia Complementation Group F Protein - metabolism / Fanconi Anemia Complementation Group G Protein - physiology / Fanconi syndrome / Fanconi's anemia / Fundamental and applied biological sciences. Psychology / Gene expression / Genetic aspects / Genetics / Hematologic and hematopoietic diseases / Homologous recombination / Homologous recombination repair / Human Genetics / Humans / Internal Medicine / Medical sciences / Medicine / Medicine & Public Health / Molecular and cellular biology / Oncogenes / Oncology / original-article / Phosphorylation / Physiological aspects / Protein-Serine-Threonine Kinases - physiology / Proteins / Recombination, Genetic / Risk factors / Serine / Serine - metabolism