Changes in protein expression due to deleterious mutations in the FA/BRCA pathway Daniela Salles a , Rosa Estela Caseira Cabral b , Julio Cesar Paixa ˜o c , Carlos Eduardo Bonacossa de Almeida d , He ´ctor N. Seua ´nez b,e , Januario Bispo Cabral-Neto a, * a Instituto de Biofı ´sica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil b Genetics Division, Instituto Nacional de Ca ˆncer, Rio de Janeiro, Brazil c Instituto Fernandes Figueira / FIOCRUZ, Brazil d Instituto de Radioprotec ¸a ˜o e Dosimetria, Comissa ˜o Nacional de Energia Nuclear, Rio de Janeiro, Brazil e Department of Genetics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil Received 3 October 2007 Available online 15 October 2007 Abstract Inherited deleterious mutations in one of the Fanconi anemia genes lead to a disease, characterized by bone marrow failure, myeloid leukemia, and hypersensitivity to DNA damage. We identified proteins likely associated to the molecular signaling pathways involved in DNA repair of interstrand cross-link lesions and in mechanisms of genomic stability mediated by FA/BRCA pathways. We compared protein maps resolved by bidimensional electrophoresis and analyzed differentially expressed proteins, by mass spectrometry, between FA complementation group C (FANCC)-deficient cells, and their ectopically corrected counterpart in physiological conditions or after treatment with MMC. We found six differentially expressed proteins; among them, the checkpoint mediator protein MDC1 whose expression was disrupted in FANCC À/À cells. The potential role of differentially expressed proteins in FA phenotype is discussed. Ó 2007 Elsevier Inc. All rights reserved. Keywords: DNA repair; DNA Damage Checkpoint; Protein expression; Genome stability Fanconi anemia (FA) is a rare, recessive genetic disorder characterized by progressive bone marrow failure leading to malignancy, mainly acute myelogenous leukemia and squamous cell carcinoma, and associated to a wide spec- trum of congenital abnormalities. At the cellular level, FA is characterized by chromosome instability and hyper- sensitivity to DNA cross-linking agents like mitomycin C (MMC), diepoxybutane (DEB) and, to a lesser extent, ion- izing radiation. MMC and DEB hypersensitivity represent FA hallmarks used as diagnostic tools [1,2]. The genetic basis of FA is manifold, with at least 12 presently described complementation groups: FANCA, FANCB, FANCC, FANCD1, FANCD2, FANCE, FANCF, FANCG, FANCI, FANCJ, FANCL, and FANCM [2]. Several studies demonstrated that proteins encoded by Fanconi genes are functional in a common pathway. Eight of these proteins are assembled in a nuclear, multi-subunit complex (FANCA, FANCB, FANCC, FANCE, FANCF, FANCG, FANCL, and FANCM) critical for the conjugation of a single ubiquitin residue to the FANCD2 protein [3–5]. This modification is required for the nuclear relocation of FANCD2 at DNA damage foci, where it co-localizes with BRCA1, RAD51, and FANCD1/BRCA2 [6,7], NBS1 [8], ATR, and RPA [9]. These nuclear foci are likely to be operative at sites where DNA is repaired by homologous recombination [10]. 0006-291X/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2007.10.025 * Corresponding author. Address: Universidade Federal do Rio de Janeiro, UFRJ, Av Brigadeiro Trompowisk s/n, CCS, Bloco C, S1045, Cidade Universita ´ria, Ilha do Funda ˜o, 21949-900 Rio de Janeiro, Brazil. Fax: +55 21 2280 8193. E-mail address: cabral@biof.ufrj.br (J.B. Cabral-Neto). www.elsevier.com/locate/ybbrc Available online at www.sciencedirect.com Biochemical and Biophysical Research Communications 364 (2007) 755–760