DNA double strand breaks (DSBs) constitute one of the most toxic lesions to occur in a cell. Unrepaired DSBs can either lead to cell death or can participate in chromosomal translocations that are hallmarks of many kinds of tumors, including lymphomas. Despite the toxicity associated with DSBs, during the immunoglobulin (Ig) gene diversification process of class switch recombination (CSR), DSBs are deliberately introduced into defined regions, called switch (S) regions, of the B cell genome, and a failure to introduce such DSBs leads to immunodeficiency syndromes. The DNA deaminase AID (activation induced cytidine deaminase) is essential for the generation of DSBs. While S regions (and the Ig gene associated variable region gene segments) are primary targets, AID has the potential to induce DSBs at non-Ig genes, including oncogenes. Such off-target DSBs are the major lesions behind the ontogeny of a large number of mature B cell lymphomas. Despite the relevance of AID targeting to both immunity and cancer, the molecular mechanisms underlying AID specificity are yet to be fully elucidated. We have now shown that noncoding RNA emanating from S regions act as molecular guides to recruit AID to S regions. This proposal tests the hypothesis that switch transcripts not only recruit AID to S regions to facilitate CSR but also sequester AID from other genomic regions to prevent collateral damage during B cell gene diversification.
In aim 1, we test the notion that the RNA-guided recruitment of AID is critical fo CSR in vivo.
In aim 2, we examine if RNA-guided AID recruitment serves to shelter the B cell genome from collateral AID-induced DNA damage.
In aim 3, we design chimeric RNA molecules for ectopic targeting of AID. These studies will have far-reaching implications into our fundamental understanding of both immunity and how simple aberrations in the process could lead to B cell lymphomas.

Public Health Relevance

Class switch recombination is essential for B cell-mediated immunity as its failure leads to immunodeficiency syndromes in humans. On the other hand, aberrant class switch recombination is directly responsible for the ontogeny of mature B cell lymphomas, the most common lymphoma in humans. Understanding the mechanisms that promote class switching while simultaneously maintaining genomic integrity is the focus of this proposal and is thus related to both human immunodeficiencies and B cell oncogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI124186-03
Application #
9413297
Study Section
Cellular and Molecular Immunology - B Study Section (CMIB)
Program Officer
Ferguson, Stacy E
Project Start
2016-02-01
Project End
2021-01-31
Budget Start
2018-02-01
Budget End
2019-01-31
Support Year
3
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Sloan-Kettering Institute for Cancer Research
Department
Type
DUNS #
064931884
City
New York
State
NY
Country
United States
Zip Code
10065
Nicolas, Laura; Cols, Montserrat; Choi, Jee Eun et al. (2018) Generating and repairing genetically programmed DNA breaks during immunoglobulin class switch recombination. F1000Res 7:458
Zheng, Simin; Kusnadi, Anthony; Choi, Jee Eun et al. (2018) NME proteins regulate class switch recombination. FEBS Lett :
Chen, Chun-Chin; Kass, Elizabeth M; Yen, Wei-Feng et al. (2017) ATM loss leads to synthetic lethality in BRCA1 BRCT mutant mice associated with exacerbated defects in homology-directed repair. Proc Natl Acad Sci U S A 114:7665-7670
Yen, Wei-Feng; Chaudhry, Ashutosh; Vaidyanathan, Bharat et al. (2017) BRCT-domain protein BRIT1 influences class switch recombination. Proc Natl Acad Sci U S A :
Vaidyanathan, Bharat; Chaudhry, Ashutosh; Yewdell, William T et al. (2017) The aryl hydrocarbon receptor controls cell-fate decisions in B cells. J Exp Med 214:197-208
Drané, Pascal; Brault, Marie-Eve; Cui, Gaofeng et al. (2017) TIRR regulates 53BP1 by masking its histone methyl-lysine binding function. Nature 543:211-216
Kunimoto, Hiroyoshi; McKenney, Anna Sophia; Meydan, Cem et al. (2017) Aid is a key regulator of myeloid/erythroid differentiation and DNA methylation in hematopoietic stem/progenitor cells. Blood 129:1779-1790
Yewdell, William T; Chaudhuri, Jayanta (2017) A transcriptional serenAID: the role of noncoding RNAs in class switch recombination. Int Immunol 29:183-196
DiMenna, Lauren J; Yen, Wei-Feng; Nicolas, Laura et al. (2017) Cutting Edge: The Transcription Factor Sox2 Regulates AID Expression in Class-Switched B Cells. J Immunol 198:2244-2248