title: Cre-loxP-mediated recombination between the SIL and SCL genes leads to a block in T-cell development at the CD4- CD8- to CD4+ CD8+ transition.
abstract: In the most common form of stem cell leukemia (SCL) gene rearrangement, an interstitial deletion of 82 kb brings SCL under the control of regulatory elements that normally govern expression of the ubiquitously expressed SCL interrupting locus (SIL) gene, which is located directly upstream of SCL. To investigate the effect of this fusion in a mouse model, a bacterial artificial chromosome (BAC) clone containing both human SIL and SCL genes was isolated, and loxP sites were inserted into intron 1 of both the SIL and SCL genes, corresponding to the sites at which recombination occurs in human T-cell acute lymphocytic leukemia patients. This BAC clone was used to generate transgenic SILloxloxSCL mice. These transgenic mice were subsequently bred to Lck-Cre mice that express the Cre recombinase specifically in the thymus. The BAC transgene was recombined between the two loxP sites in over 50% of the thymocytes from SILloxloxSCL/Cre double-transgenic mice, bringing the SCL gene under the direct control of SIL regulatory elements. Aberrant SCL gene expression in the thymus was verified by reverse transcription-polymerase chain reaction. Using FACS analysis, we found that mice carrying both SILloxloxSCL and Cre transgenes have increased CD4-/CD8- thymocytes compared with transgene-negative mice. In the spleen, these transgenic mice show a marked reduction in the number of mature CD4+ or CD8+ cells. These results demonstrate that conditional activation of SCL under control of SIL regulatory elements can impair normal T-cell development.
authors: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Naval Medical Center, Building 8, Room 5101, 8901 Wisconsin Avenue, Bethesda, MD 20889-5105, USA.
authors: Yue
authors: Y
authors: Cheng
authors: Zhenhua
authors: Z
authors: Zhang
authors: Christopher
authors: C
authors: Slape
authors: Peter D
authors: PD
authors: Aplan
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D015704:CD4 Antigens / Q000096:biosynthesis / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D016827:CD8 Antigens / Q000096:biosynthesis / Q000235:genetics; D018414:CD8-Positive T-Lymphocytes / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D002454:Cell Differentiation / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D015329:Gene Rearrangement, T-Lymphocyte / Q000235:genetics*; D006801:Humans; D019426:Integrases / Q000096:biosynthesis / Q000235:genetics*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D016513:Mice, SCID; D008822:Mice, Transgenic; D008249:Protein-Lysine 6-Oxidase / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D011995:Recombination, Genetic / Q000276:immunology; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D015704:CD4 Antigens; D016827:CD8 Antigens; D016326:Extracellular Matrix Proteins; D019426:Integrases; D047908:Intracellular Signaling Peptides and Proteins; D008249:Protein-Lysine 6-Oxidase; D011518:Proto-Oncogene Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; C071236:STIL protein, human; C067143:TAL1 protein, human; C077112:Lox protein, mouse; C045073:Cre recombinase