FANCD2 s Phase Arest FANCD2 DNA Dmage FANCA AIM FANCF (FANCG nizing Radiation FANCD2 BRCAlIBRCA2 DNA Repair (Figure by MIT OCW.) Fanconi Anemia has 8 identified complementation groups(A, B, C, D1, D2, E, F, and G)and genes for at least 7 of these groups have been identified Fanconi anemia genes, fancB and FancD1, have been identified as the Early Onset Breast Cancer gene BRCA2. Five of the Fanconi Anemia genes(FancA, FancC, FancE, FancF, and FancG) form a complex which interacts with DNA and leads to the mono-ubiquitination of the Fanc D2 protein. Through an association with BRCAl and BRCA2 in nuclear loci (represented by the light blue area in the diagram) this leads to activation of the processes that lead to DNa repair. The Atm kinase can be activated by ionizing radiation, which in turn activates many targets. One of these the FancD2 protein, is phosphorylated by ATM, which then leads to s phase arrest. An additional link in this pathway includes the phosphorylation by atM of the protein encoded by the gene of the Nijmegen Breakage Syndrome(NBS1)and BRCAl. The NB S1 protein is part of a complex which, in turn, also leads to phosphorylation of FancD2 by ATM. NBS1 appears to have two independent functions, one in inducing S-phase arrest where fancD2 is not required and the second in interacting with Fanc D2 in promoting DNA repair(see dashed arrow in diagram). Thus, FancD2 is at the cross roads of two pathways-- one leadi to s phase arrest which functions from aTM through NBS 1 and associated proteins and the other in response to dNa damage acting through the Fanconi complexFanconi Anemia has 8 identified complementation groups (A, B, C, D1, D2, E, F, and G) and genes for at least 7 of these groups have been identified. Fanconi anemia genes, FancB and FancD1, have been identified as the Early Onset Breast Cancer gene BRCA2. Five of the Fanconi Anemia genes (FancA, FancC, FancE, FancF, and FancG) form a complex which interacts with DNA and leads to the mono-ubiquitination of the FancD2 protein. Through an association with BRCA1 and BRCA2 in nuclear loci (represented by the light blue area in the diagram) this leads to activation of the processes that lead to DNA repair. The ATM kinase can be activated by ionizing radiation, which in turn activates many targets. One of these, the FancD2 protein, is phosphorylated by ATM, which then leads to S phase arrest. An additional link in this pathway includes the phosphorylation by ATM of the protein encoded by the gene of the Nijmegen Breakage Syndrome (NBS1) and BRCA1. The NBS1 protein is part of a complex which, in turn, also leads to phosphorylation of FancD2 by ATM. NBS1 appears to have two independent functions, one in inducing S-phase arrest where FancD2 is not required and the second in interacting with FancD2 in promoting DNA repair (see dashed arrow in diagram). Thus, FancD2 is at the cross roads of two pathways -- one leading to S phase arrest which functions from ATM through NBS 1 and associated proteins and the other in response to DNA damage acting through the Fanconi complex (Figure by MIT OCW.)