Project description:Nucleophosmin (NPM1) is either frequently mutated or subjected to chromosomal translocation in acute myeloid leukemia (AML). NPM protein is primarily located in the nucleus, but the recurrent NPMc+ mutation is characterized by cytoplasmic localization and leukemogenic properties. Similarly, the NPM-MLF1 translocation product favors the partial cytoplasmic retention of NPM. Regardless of their common cellular distribution, NPM-MLF1 malignancies engender different effects on hematopoiesis compared to NPMc+ counterparts, highlighting possible aberrant nuclear function(s) of NPM in NPMc+ AML. We performed a proteomics analysis and found that NPM and NPM-MLF1 interact with chromatin remodeling complexes of the ISWI family, as well as with NuRD and P/BAF complexes. Accordingly, NPM and NPM-MLF1 are recruited to transcriptionally active or repressed genes along with NuRD and P/BAF elements. Although the overall gene expression program in NPM knockdown cells is similar to that resulting from NPMc+ and is consistent with loss of nuclear function of NPM, NPM-MLF1 expression differentially altered gene transcription regulated by NPM. The abnormal gene regulation imposed by NPM-MLF1 is characterized by enhanced recruitment of NuRD to gene regulatory regions. Thus, different mechanisms orchestrate the deregulation of NPM function in NPMc+- versus NPM1-MLF1-associated leukemia.
Project description:Nucleophosmin (NPM1) is either frequently mutated or subjected to chromosomal translocation in acute myeloid leukemia (AML). NPM protein is primarily located in the nucleus, but the recurrent NPMc+ mutation is characterized by cytoplasmic localization and leukemogenic properties. Similarly, the NPM-MLF1 translocation product favors the partial cytoplasmic retention of NPM. Regardless of their common cellular distribution, NPM-MLF1 malignancies engender different effects on hematopoiesis compared to NPMc+ counterparts, highlighting possible aberrant nuclear function(s) of NPM in NPMc+ and NPM-MLF1 AML. We performed a proteomics analysis and found that NPM and NPM-MLF1 interact with chromatin remodeling complexes of the ISWI family, as well as with NuRD and P/BAF complexes. Accordingly, NPM and NPM-MLF1 are recruited to transcriptionally active or repressed genes along with NuRD and P/BAF elements. Although the overall gene expression program in NPM knockdown cells is similar to that resulting from NPMc+ and is consistent with loss of nuclear function of NPM, NPM-MLF1 expression differentially altered gene transcription regulated by NPM. The abnormal gene regulation imposed by NPM-MLF1 is characterized by enhanced recruitment of NuRD to gene regulatory regions. Thus, different mechanisms orchestrate the deregulation of NPM function in NPMc+ -versus NPM1-MLF1- associated leukemia.
Project description:Total RNA was extracted from primary T cell lymphoma that spontaneously developed in either NPM-ALK or NPM-ALK/WASP-deficent transgenic mice
Project description:Expression of key transcription factors Klf4, Oct3/4, Sox2, and c-Myc (KOSM) in embryonic stem cells can reprogram somatic cells into pluripotent cells. We found that two histone variants, TH2A and TH2B, and histone chaperone Npm enhance the KOSM-dependent generation of induced pluripotent cells (iPSCs) and produce iPSCs only with Klf4 and Oct3/4. To identify directly affected genes by these histone variants during reprogramming, we carried out gene expression profiling of MEFs overexpressing TH2A/TH2B/Npm and TH2A/TH2B deficient MEFs after infection with retroviruses expressing KOSM. A total of 21 Affymetrix Mouse Gene ST array were done for mRNA expression profiling of ES cells, iPS cells induced by Klf4, Oct4, Sox2, and c-Myc (KOSM) or Klf4, Oct4, Th2a, Th2b, and p-Npm (KOBAN), wild-type MEFs infected with retrovirus vectors expressing KOSM, KOSMBAN, or empty vector and Th2a/Th2b-deficient MEFs infected with retrovirus vector expressing KOSM.
Project description:Approximately one third of acute myeloid leukemias (AMLs) are characterized by aberrant cytoplasmic localization of Nucleophosmin (NPMc+ AML), consequent to mutations in the NPM putative nucleolar localization signal. These events are mutually exclusive with the major AML-associated chromosomal rearrangements, and are frequently associated with normal karyotype, Fms-like tyrosine kinase (FLT3) mutations and multilineage involvement. We report the gene expression profiles of 78 de novo AMLs (72 with normal karyotype; 6 with non-major chromosomal abnormalities) that were characterized for the subcellular localization and mutation status of NPM. Unsupervised clustering clearly separated NPMc+ from NPMc- AMLs, regardless of the presence of FLT3 mutations or non-major chromosomal rearrangements, supporting the concept that NPMc+ AML represents a distinct entity. The molecular signature of NPMc+ AML includes up-regulation of several genes putatively involved in the maintenance of a stem cell phenotype, suggesting that NPMc+ AML may derive from a multipotent hematopoietic progenitor. 78 de novo AMLs, negative for AML-associated chromosomal translocations at the cytogenetic and/or molecular level.
Project description:Expression of key transcription factors Klf4, Oct3/4, Sox2, and c-Myc (KOSM) in embryonic stem cells can reprogram somatic cells into pluripotent cells. We found that two histone variants, TH2A and TH2B, and histone chaperone Npm enhance the KOSM-dependent generation of induced pluripotent cells (iPSCs) and produce iPSCs only with Klf4 and Oct3/4. To identify directly affected genes by these histone variants during reprogramming, we carried out gene expression profiling of MEFs overexpressing TH2A/TH2B/Npm and TH2A/TH2B deficient MEFs after infection with retroviruses expressing KOSM.
Project description:Approximately one third of acute myeloid leukemias (AMLs) are characterized by aberrant cytoplasmic localization of Nucleophosmin (NPMc+ AML), consequent to mutations in the NPM putative nucleolar localization signal. These events are mutually exclusive with the major AML-associated chromosomal rearrangements, and are frequently associated with normal karyotype, Fms-like tyrosine kinase (FLT3) mutations and multilineage involvement. We report the gene expression profiles of 78 de novo AMLs (72 with normal karyotype; 6 with non-major chromosomal abnormalities) that were characterized for the subcellular localization and mutation status of NPM. Unsupervised clustering clearly separated NPMc+ from NPMc- AMLs, regardless of the presence of FLT3 mutations or non-major chromosomal rearrangements, supporting the concept that NPMc+ AML represents a distinct entity. The molecular signature of NPMc+ AML includes up-regulation of several genes putatively involved in the maintenance of a stem cell phenotype, suggesting that NPMc+ AML may derive from a multipotent hematopoietic progenitor.
Project description:Malignant transformation depends on genetic and epigenetic events that result in a burst of deregulated gene expression and chromatin changes. To dissect the sequence of events in this process, we used a T cell-specific lymphoma model based on the human oncogenic NPM-ALK translocation. We find that transformation of T cells shifts thymic cell populations to an undifferentiated immunophenotype, which occurs only after a period of latency, accompanied by induction of the MYC-NOTCH1 axis and deregulation of key epigenetic enzymes. We discover aberrant DNA methylation patterns, overlapping with regulatory regions, plus a high degree of epigenetic heterogeneity between individual tumors. In addition, ALK positive tumors show a loss of associated methylation patterns of neighboring CpG sites. Notably, deletion of the maintenance DNA methyltransferase DNMT1 completely abrogates lymphomagenesis in this model, despite oncogenic signaling through NPM-ALK, suggesting that faithful maintenance of tumor-specific methylation through DNMT1 is essential for sustained proliferation and tumorigenesis
Project description:Malignant transformation depends on genetic and epigenetic events that result in a burst of deregulated gene expression and chromatin changes. To dissect the sequence of events in this process, we used a T cell-specific lymphoma model based on the human oncogenic NPM-ALK translocation. We find that transformation of T cells shifts thymic cell populations to an undifferentiated immunophenotype, which occurs only after a period of latency, accompanied by induction of the MYC-NOTCH1 axis and deregulation of key epigenetic enzymes. We discover aberrant DNA methylation patterns, overlapping with regulatory regions, plus a high degree of epigenetic heterogeneity between individual tumors. In addition, ALK positive tumors show a loss of associated methylation patterns of neighboring CpG sites. Notably, deletion of the maintenance DNA methyltransferase DNMT1 completely abrogates lymphomagenesis in this model, despite oncogenic signaling through NPM-ALK, suggesting that faithful maintenance of tumor-specific methylation through DNMT1 is essential for sustained proliferation and tumorigenesis