CLONING AND ANALYSIS OF THE MURINE FANCONI-ANEMIA GROUP-C CDNA

Fanconi anemia (FA) is one of a group of disorders characterized at the cellular level by a combination of hypersensitivity to DNA-damaging agents, chromosomal instability, and defective DNA repair. Clinical features of FA include pancytopenia, often accompanied by specific congenital malformations, and a predisposition to leukemia. Since the hematological manifestations are the critical defect in terms of prognosis, FA is a candidate disease for gene replacement therapy, and the development of a mouse model system is essential for the initial stages of this work. Previously, we have cloned the gene defective in FA group C by complementation of the intrinsic sensitivity of FA cells to DNA cross-linking agents. We have now cloned the murine homologue of the human FACC cDNA. The mouse cDNA (Facc) shares 79% amino acid sequence similarity with the human gene product. The expression of the mouse cDNA in human FA(C) cells restores the cellular drug sensitivity to normal levels. Thus, the function of the protein has been conserved despite the significant sequence divergence. PCR analysis of mouse tissue RNA reveals that the gene is expressed in all adult tissues, while in situ RNA hybridization experiments show tissue specific expression at late stages of fetal development. Cross-hybridizing sequences exist in DNA from other mammals, chicken and Drosophila. These results support the hypothesis that the FACC gene product has a role in a basic aspect of cellular protection against DNA damaging agents and that this function has been conserved during evolution.