title: cDNA-library testing identifies transforming genes cooperating with c-myc in mouse pre-B cells.
abstract: While c-myc often contributes to the generation of B cell transformation, its transgenic overexpression alone does not lead to full transformation of B-lineage cells. Synergistically acting second genes must cooperate. Here, we constructed doxycycline-inducible cDNA-libraries from pre-B cell mRNA. These libraries were retrovirally transduced as single copies into single cells and overexpressed in fetal-liver-derived c-myc-overexpressing pre-B cell lines. We scored transformation by survival and/or expansion of differentiating B-lineage cells in vitro and in vivo. Only one double c-myc/cDNA-library-expressing cell line was found in less than 5 × 106library-transduced pre-B cells surviving and expressing a cDNA-library-derived transcript in vitro. This transcript was identified as a shortened form of the Exosc1 gene, encoding the RNA exosome complex component CSL4. Transplantations of double c-myc/Exosc1 short-form- or c-myc/Exosc1 full-length-transgenic cells into Rag1-/-mice resulted in survival, differentiation to CD19+CD93-sIgM+CD5low/-CD11b+mature B1 cells and, surprisingly, also vigorous expansion in vivo. Strikingly, after transplantations of c-myc/cDNA-library pre-BI cells the frequencies of double-transgenic pre-B cells and their differentiated progeny, expanding in vivo to heterogeneous phenotypes, was at least tenfold higher than in vitro. In a first analysis Ptprcap, Cacybp, Ndufs7, Rpl18a, and Rpl35a were identified. This suggests a strong influence of the host on B-cell transformation.
authors.affiliation: Max Planck Fellow Research Group, "Lymphocyte Development", Max Planck Institute for Infection Biology, Berlin, Germany. wolf@mpiib-berlin.mpg.de.
authors.forename: Inge
authors.initials: I
authors.lastname: Wolf
authors.affiliation: Max Planck Fellow Research Group, "Lymphocyte Development", Max Planck Institute for Infection Biology, Berlin, Germany.
authors.forename: Corinne
authors.initials: C
authors.lastname: Bouquet
authors.affiliation: Max Planck Fellow Research Group, "Lymphocyte Development", Max Planck Institute for Infection Biology, Berlin, Germany.
authors.forename: Fritz
authors.initials: F
authors.lastname: Melchers
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002454:Cell Differentiation; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000276:immunology; D004318:Doxycycline / Q000494:pharmacology; D015723:Gene Library; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D054448:Precursor Cells, B-Lymphoid / Q000378:metabolism*; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics* / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics
chemical_list: C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D004318:Doxycycline
keywords: B-lineage cell transformation; Exosc1; c-myc; cDNA-library overexpression