Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0598766 (leukemogenesis)
 4,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The t(11;19)(q23;p13.1) translocation is thought to play an important role in pathogenesis of myeloid leukemias in older patients. The MLL gene involved in other 11q23 abnormalities was also rearranged by this translocation. Screening of cDNA libraries of the t(11;19)(q23;p13.1)-carrying leukemic cells resulted in the isolation of several species of fusion cDNAs between the MLL gene and an unknown gene on 19p13.1, named MEN (myeloid eleven-nineteen translocation), which is ubiquitously expressed. Although the MLL gene was alternatively spliced, the fusion protein should contain an N-terminal half of the MLL, including AT hook motifs, that is fused to the MEN protein with a lysine-rich sequence, suggesting that the MLL/MEN fusion protein could be a chimeric transcription factor. The MLL/MEN fusion transcripts of 8.0 kb were detected in leukemic cells of two cases with the translocation. The MLL/MEN fusion was consistent in all three cases of the t(11;19)(q23;p13.1)-carrying leukemia examined by RNA-based polymerase chain reaction. These findings strongly suggest that the t(11;19)(q23;p13.1) results in the fusion formation encoding a new class of potential chimeric transcription factor that contributes to leukemogenesis of myeloid lineage.
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PMID:Cloning of several species of MLL/MEN chimeric cDNAs in myeloid leukemia with t(11;19)(q23;p13.1) translocation. 771 74

The t(11;19)(q23;p13.1) translocation is exclusively associated with myeloid leukemias. Previously, we cloned several species of MLL/MEN chimeric cDNAs in a patient with myeloid leukemia carrying the t(11;19)(q23;p13.1) translocation. The MEN sequence directly followed the 5' region of MLL cDNA in some species and otherwise there presented an inserted sequence of 120 bp between the MLL and MEN sequences in others. Because the insertion sequence contained an in-frame termination codon, they coded only for the NH2-terminal part of MLL (truncated MLL). We also cloned the normal MEN cDNA in full-length with a cDNA library derived from K562 cells. We expressed the normal MEN, MLL/MEN chimeric and truncated MLL proteins in COS7 cells with the corresponding cDNAs and detected them with antibodies raised against the MEN and MLL peptides. Immunostaining and subcellular fractionation showed nuclear localization of all these proteins. These findings suggested that MLL/MEN chimeric cDNAs were actually translated into both MLL/MEN fusion and truncated MLL proteins and that they were localized in the nucleus of leukemic cells. Recently, Conaway et al. reported that MEN is an RNA polymerase II elongation factor. The leukemogenesis by the t(11;19)(q23;p13.1) translocation may have resulted from the alteration of transcription regulation induced by the MLL/MEN fusion protein and/or the truncated MLL protein.
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PMID:Subcellular localization of the MEN, MLL/MEN and truncated MLL proteins expressed in leukemic cells carrying the t(11;19)(q23;p13.1) translocation. 927 49

The t(11;19)(q23;p13.1) translocation is frequently found in adult myeloid leukemia. In the MLL/MEN fusion protein generated by this translocation, most of the coding region of the MEN protein, an RNA polymerase II elongation factor, is fused to the N-terminal third of the MLL protein, a possible transcriptional regulator. However, the molecular mechanism of leukemogenesis by the fusion protein remains unclear. We investigated the effects of the fusion protein on p53 function using luciferase assays. Overexpression of the fusion protein suppressed the transactivation ability of p53. This negative effect of the fusion protein on p53 function was dependent on the region derived from MEN. Moreover, p53 coimmunoprecipitated with MLL/MEN as well as MEN, suggesting that the fusion protein binds to p53 through the MEN region. We found that MEN binding to p53 was mediated by its N-terminal region and repression of p53 transcriptional activity was mediated by its C-terminal region. We also found that these two functional regions were essential for the transformation of Rat1 cells mediated by MEN. Although we could not demonstrate a functional difference between MLL/MEN and MEN in this study, these data suggest that the MLL/MEN chimeric transcriptional regulator may exert its oncogenic activity by inhibiting the function of the p53 tumor-suppressor protein by binding to it. Our findings provide a novel insight into the leukemogenic mechanism exerted by the t(11;19)(q23;p13.1) translocation.
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PMID:Transcriptional inhibition of p53 by the MLL/MEN chimeric protein found in myeloid leukemia. 1023 72