Aberrantly resolved RAG-mediated DNA breaks in Atm-deficient lymphocytes target chromosomal breakpoints in cis.
Canonical chromosomal translocations juxtaposing antigen receptor genes and oncogenes are a hallmark of many lymphoid malignancies. These translocations frequently form through the joining of DNA ends from double-strand breaks (DSBs) generated by the recombinase activating gene (RAG)-1 and -2 proteins at lymphocyte antigen receptor loci and breakpoint targets near oncogenes. Our understanding of chromosomal breakpoint target selection comes primarily from the analyses of these lesions, which are selected based on their transforming properties. RAG DSBs are rarely resolved aberrantly in wild-type developing lymphocytes. However, in ataxia telangiectasia mutated (ATM)-deficient lymphocytes, RAG breaks are frequently joined aberrantly, forming chromosomal lesions such as translocations that predispose (ATM)-deficient mice and humans to the development of lymphoid malignancies. Here, an approach that minimizes selection biases is used to isolate a large cohort of breakpoint targets of aberrantly resolved RAG DSBs in Atm-deficient lymphocytes. Analyses of this cohort revealed that frequently, the breakpoint targets for aberrantly resolved RAG breaks are other DSBs. Moreover, these nonselected lesions exhibit a bias for using breakpoints in cis, forming small chromosomal deletions, rather than breakpoints in trans, forming chromosomal translocations.
Mahowald
Grace K
GK
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Baron
Jason M
JM
Mahowald
Michael A
MA
Kulkarni
Shashikant
S
Bredemeyer
Andrea L
AL
Bassing
Craig H
CH
Sleckman
Barry P
BP
D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D019457:Chromosome Breakage; D033481:Chromosomes, Mammalian / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000172:deficiency* / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D011946:Receptors, Antigen / Q000276:immunology; D014178:Translocation, Genetic; D025521:Tumor Suppressor Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C499308:Rag2 protein, mouse; D011946:Receptors, Antigen; D025521:Tumor Suppressor Proteins; C064658:RAG-1 protein; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases