title: MN1-TEL myeloid oncoprotein expressed in multipotent progenitors perturbs both myeloid and lymphoid growth and causes T-lymphoid tumors in mice.
abstract: The MN1-TEL (meningioma 1-translocation-ETS-leukemia) fusion oncoprotein is the product of the t(12;22)(p13;q11) in human myeloid leukemia consisting of N-terminal MN1 sequences, a transcriptional coactivator, fused to C-terminal TEL sequences, an E26-transformation-specific (ETS) transcription factor. To analyze the role of MN1-TEL in leukemogenesis, we created a site-directed transgenic (knock-in) mouse model carrying a conditional MN1-TEL transgene under the control of the Aml1 regulatory sequences. After induction, MN1-TEL expression was detected in both myeloid and lymphoid cells. Activation of MN1-TEL expression enhanced the repopulation ability of myeloid progenitors in vitro as well as partially inhibited their differentiation in vivo. MN1-TEL also promoted the proliferation of thymocytes while it blocked their differentiation from CD4-/CD8- to CD4+/CD8+ in vivo. After long latency, 30% of the MN1-TEL-positive mice developed T-lymphoid tumors. This process was accelerated by N-ethyl-N-nitrosourea-induced mutations. MN1-TEL-positive T-lymphoid tumors showed elevated expression of the Notch-1, Hes-1, c-Myc, and Lmo-2 genes while their Ink4a/pRB and Arf/p53 pathways were impaired, suggesting that these alterations cooperatively transform T progenitors. We conclude that MN1-TEL exerts its nonlineage-specific leukemogenic effects by promoting the growth of primitive progenitors and blocking their differentiation, but cooperative mutations are necessary to fully induce leukemic transformation.
authors.affiliation: Department of Genetics and Tumor Cell Biology, St Jude Children's Research Hospital, 332 North Lauderdale, Memphis, TN 38105, USA.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawagoe
authors.forename: Gerard C
authors.initials: GC
authors.lastname: Grosveld
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007951:Leukemia, Myeloid / Q000235:genetics; D015458:Leukemia, T-Cell / Q000378:metabolism* / Q000473:pathology*; D008214:Lymphocytes / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D023461:Myeloid Progenitor Cells / Q000378:metabolism*; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D015398:Signal Transduction; D015996:Survival Rate; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C417770:MN1-TEL fusion protein, human; D015514:Oncogene Proteins, Fusion; D014157:Transcription Factors