Analysis of the V(D)J recombination efficiency at lymphoid chromosomal translocation breakpoints.
Chromosomal translocations and deletions are among the major events that initiate neoplasia. For lymphoid chromosomal translocations, misrecognition by the RAG (recombination activating gene) complex of V(D)J recombination is one contributing factor that has long been proposed. The chromosomal translocations involving LMO2 (t(11;14)(p13;q11)), Ttg-1 (t(11;14)(p15;q11)), and Hox11 (t(10;14)(q24;q11)) are among the clearest examples in which it appears that a D or J segment has synapsed with an adventitious heptamer/nonamer at a gene outside of one of the antigen receptor loci. The interstitial deletion at 1p32 involving SIL (SCL-interrupting locus)/SCL (stem cell leukemia) is a case involving two non-V(D)J sites that have been suggested to be V(D)J recombination mistakes. Here we have used our human extrachromosomal substrate assay to formally test the hypothesis that these regions are V(D)J recombination misrecognition sites and, more importantly, to quantify their efficiency as V(D)J recombination targets within the cell. We find that the LMO2 fragile site functions as a 12-signal at an efficiency that is only 27-fold lower than that of a consensus 12-signal. The Ttg-1 site functions as a 23-signal at an efficiency 530-fold lower than that of a consensus 23-signal. Hox11 failed to undergo recombination as a 12- or 23-signal and was at least 20,000-fold less efficient than consensus signals. SIL has been predicted to function as a 12-signal and SCL as a 23-signal. However, we find that SIL actually functions as a 23-signal. These results provide a formal demonstration that certain chromosomal fragile sites can serve as RAG complex targets, and they determine whether these sites function as 12- versus 23-signals. These results quantify one of the three major factors that determine the frequency of these translocations in T-cell acute lymphocytic leukemia.
Raghavan
S C
SC
Department of Pathology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90089-9176, USA.
Kirsch
I R
IR
Lieber
M R
MR
D048868:Adaptor Proteins, Signal Transducing; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D002874:Chromosome Mapping; D002877:Chromosomes, Human; D002878:Chromosomes, Human, Pair 1; D002879:Chromosomes, Human, Pair 10; D002880:Chromosomes, Human, Pair 11; D002883:Chromosomes, Human, Pair 14; D016384:Consensus Sequence; D004254:DNA Nucleotidyltransferases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics*; D016654:Genes, RAG-1; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D007938:Leukemia / Q000235:genetics; D015459:Leukemia-Lymphoma, Adult T-Cell; D008667:Metalloproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000235:genetics; D015514:Oncogene Proteins, Fusion; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics; D011995:Recombination, Genetic; D017384:Sequence Deletion; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured; D045567:VDJ Recombinases
D048868:Adaptor Proteins, Signal Transducing; D051792:Basic Helix-Loop-Helix Proteins; D004254:DNA Nucleotidyltransferases; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D008667:Metalloproteins; D015513:Oncogene Proteins; D015514:Oncogene Proteins, Fusion; D011506:Proteins; D011518:Proto-Oncogene Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D014157:Transcription Factors; D045567:VDJ Recombinases; C065072:LMO1 protein, human; C085117:LMO2 protein, human; C071236:STIL protein, human; C067143:TAL1 protein, human; C071250:TLX1 protein, human