Final Report Summary - AID AND BEYOND (AID in adaptive immunity and beyond)
We have performed complementary approaches to elucidate the role of AID in the germ-line and in CSR, combining clinical results, mice models, genetically engineered molecules and functional assays. Specifically, we have shown that the expression of AID in the germ-line has no impact on the frequency of meiotic recombination, which is a significant contribution for the community working on AID and genome stability. In addition, we have found in females that the AID protein is expressed mainly in the somatic granulosa cells surrounding the oocyte, an observation that raises a number of new hypotheses concerning the role of AID in the protection of the genome of the gametes. On a different front, we have tested AID orthologs from a shark and a sturgeon using functional assays, thus showing that the specific ability of the C-terminus of AID to drive CSR evolved at least 50 million years before the appearance of CSR in Tetrapods (amphibians, reptiles, birds and mammals) and that such function was conserved in independent evolutionary branches for 450 million years. This paradoxical finding suggested that a conserved role of the C-terminus of AID was coopted in the context of CSR and using chimeric molecules we have shown that such role is not only conserved in AID orthologs but shared with the other enzyme that introduces physiologic double-strand breaks in lymphocytes. Future experiments will detail the exact nature of this function, but the available evidence points to the active recruitment of a DNA repair pathway.
1. Trancoso I, Cortesao CS, Zhao Y, Hammarstr?m QP, Barreto VM (in preparation). The RAG1/RAG2 complex and Activation-Induced Cytidine Deaminase converged for the recruitment of the Non-Homologous End Joining repair pathway.
2. Carat?o N, Reis PH, Freitas RF, Cortes?o CS, Jacob CMA, Pastorino AC, Carneiro-Sampaio M, Barreto VM (ready for submission) A Novel Activation-Induced Cytidine Deaminase (AID) Mutation in patients with hyper-IgM type 2 syndrome.
3. Cortes?o SCS, Freitas RF, Barreto VM (submitted) Activation-Induced Cytidine Deaminase does not impact on murine meiotic recombination.
4. Barreto VM and Magor B. (2011) Activation-induced cytidine deaminase structure and functions: A species comparative view. " Developmental & Comparative Immunology. 35 (9): 991-1007.
5. Pavri R, Gazumyan A, Jankovic M, Di Virgilio M, Klein I, Ansarah-Sobrinho C, Resch W, Yamane A, Reina San-Martin B, Barreto VM, Nieland TJ, Root DE, Casellas R, Nussenzweig MC. (2010) Activation-induced cytidine deaminase targets DNA at sites of RNA polymerase II stalling by interaction with Spt5. Cell 143 (1): 122-33