Thymocyte expression of RAG-1 and RAG-2: termination by T cell receptor cross-linking.
The expression of the V(D)J [variable (diversity) joining elements] recombination activating genes, RAG-1 and RAG-2, has been examined during T cell development in the thymus. In situ hybridization to intact thymus and RNA blot analysis of isolated thymic subpopulations separated on the basis of T cell receptor (TCR) expression demonstrated that both TCR- and TCR+ cortical thymocytes express RAG-1 and RAG-2 messenger RNA's. Within the TCR+ population, RAG expression was observed in immature CD4+CD8+ (double positive) cells, but not in the more mature CD4+CD8- or CD4-CD8+ (single positive) subpopulations. Thus, although cortical thymocytes that bear TCR on their surface continue to express RAG-1 and RAG-2, it appears that the expression of both genes is normally terminated during subsequent thymic maturation. Since thymocyte maturation in vivo is thought to be regulated through the interaction of the TCR complex with self major histocompatibility complex (MHC) antigens, these data suggest that signals transduced by the TCR complex might result in the termination of RAG expression. Consistent with this hypothesis, thymocyte TCR cross-linking in vitro led to rapid termination of RAG-1 and RAG-2 expression, whereas cross-linking of other T cell surface antigens such as CD4, CD8, or HLA class I had no effect.
Turka
L A
LA
Department of Internal Medicine, University of Michigan, Ann Arbor 48109.
Schatz
D G
DG
Oettinger
M A
MA
Chun
J J
JJ
Gorka
C
C
Lee
K
K
McCormack
W T
WT
Thompson
C B
CB
D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology; D017252:CD3 Complex; D002454:Cell Differentiation; D002470:Cell Survival; D004254:DNA Nucleotidyltransferases / Q000235:genetics*; D004268:DNA-Binding Proteins; D015870:Gene Expression; D015329:Gene Rearrangement, T-Lymphocyte; D018398:Homeodomain Proteins; D006801:Humans; D051379:Mice; D009687:Nuclear Proteins; D009693:Nucleic Acid Hybridization; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D011940:Receptor Aggregation; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015375:Receptors, Interleukin-2 / Q000235:genetics; D016176:T-Lymphocyte Subsets / Q000201:enzymology / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000201:enzymology*; D045567:VDJ Recombinases
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D011506:Proteins; C499311:RAG2 protein, human; D012333:RNA, Messenger; C499308:Rag2 protein, mouse; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; C064655:V(D)J recombination activating protein 2; C064658:RAG-1 protein; D004254:DNA Nucleotidyltransferases; D045567:VDJ Recombinases