Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The DNA binding activity of FUS (also known as TLS), a nuclear pro-oncogene involved in multiple translocations, is regulated by BCR-ABL in a protein kinase CbetaII (PKCbetaII)-dependent manner. We show here that in normal myeloid progenitor cells FUS, although not visibly ubiquitinated, undergoes proteasome-dependent degradation, whereas in BCR-ABL-expressing cells, degradation is suppressed by PKCbetaII phosphorylation. Replacement of serine 256 with the phosphomimetic aspartic acid prevents proteasome-dependent proteolysis of FUS, while the serine-256-to-alanine FUS mutant is unstable and susceptible to degradation. Ectopic expression of the phosphomimetic S256D FUS mutant in granulocyte colony-stimulating factor-treated 32Dcl3 cells induces massive apoptosis and inhibits the differentiation of the cells escaping cell death, while the degradation-prone S256A mutant has no effect on either survival or differentiation. FUS proteolysis is induced by c-Jun, is suppressed by BCR-ABL or Jun kinase 1, and does not depend on c-Jun transactivation potential, ubiquitination, or its interaction with Jun kinase 1. In addition, c-Jun-induced FUS proteasome-dependent degradation is enhanced by heterogeneous nuclear ribonucleoprotein (hnRNP) A1 and depends on the formation of a FUS-Jun-hnRNP A1-containing complex and on lack of PKCbetaII phosphorylation at serine 256 but not on FUS ubiquitination. Thus, novel mechanisms appear to be involved in the degradation of FUS in normal myeloid cells; moreover, the ability of the BCR-ABL oncoprotein to suppress FUS degradation by the induction of posttranslational modifications might contribute to the phenotype of BCR-ABL-expressing hematopoietic cells.
Mol Cell Biol 2000 Aug
PMID:BCR-ABL prevents c-jun-mediated and proteasome-dependent FUS (TLS) proteolysis through a protein kinase CbetaII-dependent pathway. 1091 97

A multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) assay for both major forms of BCR-ABL was compared with fluorescence in situ hybridization (FISH), karyotyping, and Southern blotting for disease monitoring in 37 follow-up bone marrow samples from 32 patients with Ph1-positive leukemia. Of these 37 samples, 33 were from patients with chronic myeloid leukemia (CML) (26 post allogeneic bone marrow transplantation [AlloBMT] and seven during interferon-alpha therapy) and 4 from Ph1-positive acute lymphoblastic leukemia (ALL) patients (1 post AlloBMT and 3 post high dose chemotherapy). For the 27 samples studied after AlloBMT (26 CML and 1 Ph1-positive ALL) the time after transplantation ranged from 1 to 107 months (median 47.5 months). In 8 (22%) of the 37 samples there were discrepant results among methods. The discrepancy rates relative to other techniques were: karyotyping 17% (5 of 29), Southern blotting 18% (6 of 33), multiplex RT-PCR 8% (3 of 37), and FISH 8% (3 of 37). Therefore, the relative accuracy of each method for disease monitoring in Ph1-positive leukemia was: 83% (24 of 29) for karyotyping, 82% (27 of 33) for Southern blotting, 92% (34 of 37) for FISH, and 92% (34 of 37) for multiplex RT-PCR. This multiplex RT-PCR assay appears equivalent to FISH in terms of accuracy, simplicity, and turnaround time and both are superior to Southern blot and conventional cytogenetics in the laboratory monitoring of Ph1-positive leukemias.
Diagn Mol Pathol 2000 Dec
PMID:Comparison of a multiplex reverse transcriptase-polymerase chain reaction for BCR-ABL to fluorescence in situ hybridization, Southern blotting, and conventional cytogenetics in the monitoring of patients with Ph1-positive leukemias. 1112 44

TEL-JAK2 fusion proteins, which are a result of t(9;12)(p24;p13) translocations associated with human leukemia, activate Stat5 in vitro and in vivo and cause a myelo- and lymphoproliferative disease in a murine bone marrow transplant model. We report that Socs-1, a member of the SOCS family of endogenous inhibitors of JAKs and STATs, inhibits transformation of Ba/F3 cells by TEL-JAK2 but has no effect on Ba/F3 cells transformed by BCR-ABL, TEL-ABL, or TEL-platelet-derived growth factor receptor beta. TEL-JAK2, in addition to activating Stat5, associates with Shc and Grb2 and induces activation of Erk2, and expression of Socs-1 inhibits engagement of each of these signaling molecules. TEL-JAK2 kinase activity is inhibited by Socs-1, as assessed by in vitro kinase assays. In addition, Socs-1 induces proteasomal degradation of TEL-JAK2. Mutational analysis indicates that the SOCS box of Socs-1 is required for proteasomal degradation and for abrogation of growth of TEL-JAK2-transformed cells. Furthermore, murine bone marrow transplant assays demonstrate that expression of Socs-1 prolongs latency of TEL-JAK2-mediated disease in vivo. Collectively, these data indicate that Socs-1 inhibits TEL-JAK2 in vitro and in vivo through inhibition of kinase activity and induction of TEL-JAK2 protein degradation.
Mol Cell Biol 2001 May
PMID:Socs-1 inhibits TEL-JAK2-mediated transformation of hematopoietic cells through inhibition of JAK2 kinase activity and induction of proteasome-mediated degradation. 1131 80

The potential efficacy of prodrug activation of a transduced suicide gene in a cancer cell may be impaired or enhanced by oncoproteins produced by that cell. In the context of a gene therapy protocol for chronic myeloid leukemia (CML) we examined whether the Bcr-Abl fusion protein would have either of these effects. Thus, the mechanism of cell killing by transfer of herpes simplex virus thymidine kinase (HSV-tk) and subsequent ganciclovir (GCV) treatment was examined in pre-B (TonB210.1) cells and myeloid cells (32D) and in their BCR-ABL-expressing counterparts. HSV-tk-transduced cell lines, either in the presence or in the absence of BCR-ABL expression, became susceptible to GCV at concentrations which were nontoxic to the nontransduced cells. This susceptibility was represented by apoptotic cell death in all cases. Apoptosis was observed after 24 h of treatment with GCV in the tk-transduced parental cells and in the BCR-ABL-expressing TonB210.1 cells but only after a delay of more than 24 h in the 32Dp210 cells compared to 32D. Cell death in the BCR-ABL-expressing clones was preceded by S- and G2/M-phase cell cycle arrest. Activation of FAS/APO-1 and caspase-8 was observed in all the tk-transduced cell lines after GCV treatment. However, the caspase-8 inhibitor Z-IETD-FMK only partially abrogated tk/GCV-induced apoptosis. A possible role for inhibition of Bcl-2 or Bcl-x(L) expression in the apoptosis induced by GCV was observed in the tk-transduced TonB210.1 cells but not in the 32D or 32Dp210 cells. The data demonstrate that expression of the Bcr-Abl oncoprotein does not block the apoptosis induced by the HSV-tk/GCV system, suggesting that this suicide gene therapy strategy could be considered for the treatment of CML in blast crisis.
Mol Ther 2001 May
PMID:BCR-ABL-expressing cells transduced with the HSV-tk gene die by apoptosis upon treatment with ganciclovir. 1135 68

There are two commonly used approaches to modeling human leukemia in mice: generation of mutant mice by traditional transgenic or knock-out/knock-in methods and retroviral bone marrow transduction and transplantation. For modeling leukemia, the retroviral model system has some distinct advantages over transgenic mice. Testing different forms and mutants of a given oncogene is much easier with the retroviral system and avoids the potential deleterious effects of expression of a transgene in nonhematopoietic tissues and during development. The retroviral provirus serves as a clonal marker of a transduced cell, facilitating analysis of clonality and transplantability of the malignancy. Finally, the retroviral system allows the assessment of the action of an oncogene in different subsets of hematopoietic precursor cells in the bone marrow, which is difficult or impossible with transgenic models. This article summarizes recent progress in modeling human Philadelphia-positive leukemia in mice with the retroviral bone marrow transduction/transplantation system and emphasizes the advantages and limitations of this approach with examples from the BCR-ABL leukemogenesis literature.
Blood Cells Mol Dis
PMID:Retroviral transduction models of Ph+ leukemia: advantages and limitations for modeling human hematological malignancies in mice. 1135 80

p210bcr/abl is detected in almost all chronic myelogenous leukemia (CML) patients and a significant number of acute lymphoblastic leukemia (ALL) cases. It is generated by a reciprocal chromosomal translocation, t(9;22) (q34;q11), and the enhanced kinase activity of the protein is believed to be implicated in the pathogenesis of the diseases. To examine its oncogenicity in vivo and to create an animal model for BCR/ABL-positive leukemias, we generated transgenic mice expressing p210bcr/abl driven by the promoter of the mouse tec gene, a cytoplasmic tyrosine kinase preferentially expressed in early hematopoietic progenitors. While the founder mice showed excessive proliferation of lymphoblasts shortly after birth and were diagnosed as ALL, the transgenic progeny reproducibly exhibited marked granulocyte hyperplasia with thrombocytosis after a long latent period, which closely resembles the clinical course of human CML. In addition, to investigate whether loss of p53 would play a role in the transition from chronic phase to blast crisis of CML, we crossmated p210bcr/abl transgenic (BCR/ABLtg/-) mice with p53 heterozygous (p53+/-) mice and generated p210bcr/abl transgenic, p53 heterozygous (BCR/ABLtg/- p53+/-) mice, in which a somatic alteration in the residual p53 allele directly abrogates p53 function. The BCR/ABLtg/- p53+/- mice exhibited rapid proliferation of blast cells and died in a short period compared with their wild-type (BCR/ABL-/- p53+/+), p53 heterozygous (BCR/ABL-/- p53+/-), and p210bcr/abl transgenic (BCR/ABLtg/- p53+/+) littermates. Interestingly, the normal p53 allele was frequently and preferentially lost in the tumor tissues, providing in vivo evidence that acquired loss of p53 contributes to the blastic transformation of p210bcr/abl-expressing hematopoietic cells. Our transgenic mice will be a useful model for investigating oncogenic properties of p210bcr/abl in vivo and will provide insights into the molecular mechanism(s) underlying the progression from chronic phase to blast crisis of CML.
Blood Cells Mol Dis
PMID:Model mice for BCR/ABL-positive leukemias. 1135 87

We demonstrated previously that an allosterically controllable novel ribozyme, designated the maxizyme, is a powerful tool for disruption of an abnormal chimeric RNA target [BCR-ABL (b2a2) mRNA], and we proposed that it might provide the basis for future gene therapy for the treatment of chronic myelogenous leukemia (Kuwabara et al. Mol. Cell 1998, 2, 617-627). The maxizyme has sensor arms that can recognize a specific sequence and, in the presence exclusively of such a specific sequence, it can form a cavity for capture of catalytically indispensable Mg2+ ions. Cleavage of the target RNA then occurs at a site distant from the specific sequence. Clearly, the specific sequences recognized by sensor arms should not be limited to those of the above mentioned abnormal chimeric target. Thus, to demonstrate the general applicability of maxizyme technology, we constructed maxizymes targeted to other mRNAs, such as PML-RAR alpha mRNA, sDLST mRNA, and BCR-ABL (b1a2) mRNA, that are not cleaved with high specificity by the wild-type hammerhead ribozyme. Specific and efficient cleavage in vitro of these mRNAs by the custom-designed maxizymes demonstrated clearly that maxizyme technology is not limited to a specific case but may have broad general applicability in molecular biology and, also, in a clinical setting.
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PMID:Maxizymes, novel allosterically controllable ribozymes, can be designed to cleave various substrates. 1170 32

For the treatment of chronic myelogenous leukemia (CML), attempts have been made to design various ribozyme motifs that can specifically recognize and cleave BCR-ABL fusion mRNAs. In the case of L6 BCR-ABL b2a2 mRNA, it is difficult to cleave the abnormal mRNA specifically because the mRNA includes no sequences that can be cleaved efficiently by conventional hammerhead ribozymes near the BCR-ABL junction. We recently succeeded in designing a novel maxizyme, which specifically cleaves BCR-ABL fusion mRNA, as a result of the formation of a dimeric structure [Kuwabara, T.; et al. Mol. Cell 1998, 2, 617-627; Tanabe, T.; et al. Nature 2000, 406, 473-474]. Specifically, we tailored the maxizyme with molecular switching function: the maxizyme splices a cleavable GUC site, but only when it appears within a strand of mRNA that possesses the abnormal splice junction. We demonstrated that this approach is generalizable [Tanabe, T.; et al. Biomacromolecules 2000, 1, 108-117]. All the maxizymes designed in the past functioned as a result of the formation of a dimeric structure. Questions have been asked whether a similar molecular switching might be possible within a single molecule when two monomer units of the maxizyme were connected via a linker sequence. We found that an analogous conformational change could not be induced within a single molecule when two maxizyme units were simply connected via a nonregulatable linker sequence. However, an active conformation was achieved by the introduction of an antisense modulator within the linker sequence that adjusted the overall structure to the correct form. Results of studies in cultured cells suggested that the desired conformational change could indeed be induced within the modified single-chained maxizyme and such a construct caused apoptosis only in leukemic cells with the Philadelphia chromosome.
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PMID:Allosterically controlled single-chained maxizymes with extremely high and specific activity. 1171 33

A variety of normal human tissues have been reported to harbor small cell populations carrying potentially oncogenic gene rearrangements. This backdrop of mutant cells may be present in the majority of healthy individuals and is apparently weakly selected against. This may provide empirical support for the concept of global neutrality, or near-neutrality (very weak selection), of many somatic mutations. Many healthy individuals, as well as patients with chronic myeloid leukemia, manifest the BCR-ABL fusion gene in blood cells. The presumed neutrality of the BCR-ABL rearrangement-carrying pluripotential hematopoietic stem cells and the relative uniformity of the incidence rate of CML worldwide were used to estimate the extent of the background of BCR-ABL-positive stem cells and the numerical size of the human pluripotential hematopoietic stem cell pool. Three different approaches (molecular-epidemiological, statistical, and population genetical) were employed. Each resulted in very similar estimates of the size of the stem cells carrying the BCR-ABL allele fusions (1.4 x 10(4) cells) and the size of the total human stem cell pool (1.6 x 10(9) cells per individual). The implication of these estimates in the context of the hierarchical nature of the stem cell pool is also considered. The presumptive smaller-sized population of CD34(-) stem cells could not be characterized by any of the approaches used as a "founding" population, representing an ultimate source of all hematopoietic progenitors, or as a subset of stem cells comprising a deeper "kinetic" segment of the total (10(9)-sized) stem cell compartment.
Blood Cells Mol Dis
PMID:The fundamental prevalence of chronic myeloid leukemia-generating clonogenic cells in the light of the neutrality theory of evolution. 1178 55

The E2A locus is a frequent target of chromosomal translocations in B-cell acute lymphoblastic leukemia (B-ALL). E2A encodes two products, E12 and E47, that are part of the basic helix-loop-helix (bHLH) family of transcription factors and are central in B lineage differentiation. E2A haplo-insufficiency hinders progression through three major checkpoints in B-cell development: commitment into the B lineage, at the pro-B to pre-B transition, and in the induction of immunoglobulin M (IgM) expression required for a functional BCR. These observations underscore the importance of E2A gene dosage in B-cell development. Here we show that a higher proportion of pro-B cells in E2A(+/-) mice is in the cell cycle compared to that in wild-type littermates. This increase correlates with lower p21(waf/cip1) levels, indicating that E2A has an antiproliferative function in B-cell progenitors. Ectopic expression in the B lineage of SCL/Tal1, a tissue-specific bHLH factor that inhibits E2A function, blocks commitment into the B lineage without affecting progression through later stages of differentiation. Furthermore, ectopic SCL expression exacerbates E2A haplo-insufficiency in B-cell differentiation, indicating that SCL genetically interacts with E2A. Taken together, these observations provide evidence for a gradient of E2A activity that increases from the pre-pro-B to the pre-B stage and suggest a model in which low levels of E2A (as in pro-B cells) are sufficient to control cell growth, while high levels (in pre-B cells) are required for cell differentiation. The antiproliferative function of E2A further suggests that in B-ALL associated with t(1;19) and t(17;19), the disruption of one E2A allele contributes to leukemogenesis, in addition to other anomalies induced by E2A fusion proteins.
Mol Cell Biol 2002 Feb
PMID:Gradient of E2A activity in B-cell development. 1178 64


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