title: Overexpression of a transcription factor LYL1 induces T- and B-cell lymphoma in mice.
abstract: LYL1, a member of the class II basic helix-loop-helix transcription factors, is aberrantly expressed in a fraction of human T-cell acute lymphoblastic leukemia. Here, we generated transgenic mice ubiquitously overexpressing LYL1 using a construct expressing full-length cDNA driven by a human elongation factor 1alpha promoter. Four independent lines exhibiting high LYL1 expression were established. Of these transgenic mice, 96% displayed loss of hair with a short kinked tail. Furthermore, 30% of them developed malignant lymphoma, with an average latent period of 352 days. In these mice, histological examination revealed tumor cell infiltration in multiple organs and immunohistochemical analysis showed that the infiltrated tumor cells were either CD3 or CD45R/B220-positive; fluorescence-activated cell sorter analysis indicated that each tumor consisted either of mainly CD4, CD8 double-positive T cells or mature B cells; the clonality of LYL1-induced lymphoma was confirmed by T-cell receptor rearrangement and immunoglobulin heavy-chain gene rearrangement analyses. Mammalian two-hybrid analysis and luciferase assay suggested that excess LYL1 blocked the dimerization of E2A and thus inhibited the regulatory activity of E2A on the CD4 promoter. Reverse transcription-polymerase chain reaction results showed that the expression of certain E2A/HEB target genes was downregulated. Taken together, our results provide direct evidence that aberrant expression of LYL1 plays a role in lymphomagenesis.
authors.affiliation: Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhong
authors.forename: L
authors.initials: L
authors.lastname: Jiang
authors.forename: H
authors.initials: H
authors.lastname: Hiai
authors.forename: S
authors.initials: S
authors.lastname: Toyokuni
authors.forename: Y
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D019281:Dimerization; D015329:Gene Rearrangement, T-Lymphocyte; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D016130:Immunophenotyping; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D016393:Lymphoma, B-Cell / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D016399:Lymphoma, T-Cell / Q000209:etiology* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D008156:Luciferases; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D000073942:T-Cell Acute Lymphocytic Leukemia Protein 1; D044767:Ubiquitin-Protein Ligases; C490130:Lyl1 protein, mouse; C407909:TCF3 protein, human; C067143:TAL1 protein, human; C073366:TCF12 protein, human; C489657:LRSAM1 protein, human