Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, we compared the impact of two protein kinase (PK) inhibitors, H-7 and staurosporine, on the normal myeloid progenitors (CFU-GM) and acute myeloid leukemia progenitors (AML-CFU) proliferation measured by in vitro clonogenic assay. H-7 and staurosporine displayed a biphasic dose-effect on both CFU-GM and AML-CFU recovery. At the lowest concentration range (0.1 microM to 20 microM for H-7 and 0.1 nM to 1 nM for staurosporine), we observed growth stimulation whereas higher concentrations induced dose-dependent growth inhibition. Moreover, AML-CFU proved to be significantly more sensitive to the inhibitory effect of both H-7 and staurosporine than CFU-GM (3.16- and 2.12-fold, respectively). These results were further confirmed with comparable murine cell line models (FDC-P1, a hematopoietic cell line generated from normal bone marrow and WEHI, a myelomonocytic leukemia cell line). Furthermore, we report that both H-7 and staurosporine present similar inhibitory effects on proliferation (PE1) as on self-renewal (PEs) of AML-CFU. In an attempt to understand more fully the mechanism of action of H-7 and staurosporine, we investigated their impact (when used at their D50) on the human myelogenous leukemia cell line, K562. H-7 and staurosporine induced a transient decrease of cell growth, between 0 and 24 hours, and produced a transient blockade of K562 cells in the S-phase, either 24 or 48 hours after the addition of staurosporine and H-7, respectively.
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PMID:Effects of H-7 and staurosporine on proliferation and self-renewal of acute myeloid leukemia progenitors. 850 77

The aim of the present study was to elucidate events related to receptor function, signal transmission and cytoskeletal rearrangements concurrent with Porphyromonas gingivalis invasion of oral epithelial cells in vitro. Porphyromonas gingivalis strain FDC 381 and the KB cell line (ATCC CCL 17) were used in a previously described antibiotic protection assay. The involvement of a receptor-mediated endocytosis pathway in the internalization process was demonstrated after treatment of the epithelial cells with monodansylcadaverine and ouabain, substances that inhibit formation of coated pits, resulting in reduction in the number of invading P. gingivalis: Treatment of the epithelial cells with the protein kinase (PK) inhibitor staurosporine and the tyrosine-specific PK inhibitor genistein was also found to significantly decrease the number of invading bacteria, suggesting involvement of tyrosine phosphorylation in signal transduction during invasion. This was further supported by the identification of a 43 kD protein acting as a substrate for tyrosine phosphorylation subsequent to the microbial-host cell interaction. Tyrosine phosphorylation of the 43 kD protein was strongly reduced by treatment with PK inhibitors. The decrease in invasion observed after treatment of epithelial cells with colchicine and nocodazole, inhibitors of microtubuli polymerization, suggested that the bacterial-receptor interaction and the phosphotyrosine-dependent intracellular signalling trigger an internalization process involving rearrangements of cytoskeletal microtubuli.
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PMID:Cellular events concurrent with Porphyromonas gingivalis invasion of oral epithelium in vitro. 893 May 84

The histone H4 gene promoter provides a paradigm for defining transcriptional control operative at the G1/S phase transition point in the cell cycle. Transcription of the cell cycle-dependent histone H4 gene is upregulated at the onset of S phase, and the cell cycle control element that mediates this activation has been functionally mapped to a proximal promoter domain designated Site II. Activity of Site II is regulated by an E2F-independent mechanism involving binding of the oncoprotein IRF2 and the multisubunit protein HiNF-D, which contains the homeodomain CDP/cut, CDC2, cyclin A, and the tumor suppressor pRb. To address mechanisms that define interactions of Site II regulatory factors with this cell cycle control element, we have investigated these determinants of transcriptional regulation at the G1/S phase transition in FDC-P1 hematopoietic progenitor cells. The representation and activities of histone gene regulatory factors were examined as a function of FDC-P1 growth stimulation. We find striking differences in expression of the pRb-related growth regulatory proteins (pRb/p105, pRb2/p130, and p107) following the onset of proliferation. pRb2/p130 is present at elevated levels in quiescent cells and declines following growth stimulation. By contrast, pRb and p107 are minimally represented in quiescent FDC-P1 cells but are upregulated at the G1/S phase transition point. We also observe a dramatic upregulation of the cellular levels of pRb2/p130-associated protein kinase activity when S phase is initiated. Selective interactions of pRb and p107 with CDP/cut are observed during the FDC-P1 cell cycle and suggest functional linkage to competency for DNA binding and/or transcriptional activity. These results are particularly significant in the context of hematopoietic differentiation where stringent control of the cell cycle program is requisite for expanding the stem cell population during development and tissue renewal.
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PMID:Cell cycle-dependent modifications in activities of pRb-related tumor suppressors and proliferation-specific CDP/cut homeodomain factors in murine hematopoietic progenitor cells. 928 29

Interleukin 3 (IL-3) stimulates the net growth of murine factor-dependent NSF/N1.H7 and FDC-P1/ER myeloid cells by stimulating proliferation and suppressing apoptosis. Recently, we discovered that Bcl2 is phosphorylated at an evolutionarily conserved serine residue (Ser70) after treatment with the survival agonists IL-3 or bryostatin 1, a potent activator of protein kinase (Ito, T., Deng, X., Carr, B., and May, W. S. (1997) J. Biol. Chem. 272, 11671-11673). In addition, an intact Ser70 was found to be required for Bcl2's ability to suppress apoptosis after IL-3 withdrawal or toxic chemotherapy. We now show that phosphorylation of Bcl2 occurs rapidly after the addition of agonist to IL-3-deprived cells and can be reversed by the action of an okadaic acid (OA)-sensitive phosphatase. A role for protein phosphatase (PP) 2A as the Bcl2 regulatory phosphatase is supported by several observations: 1) dephosphorylation of Bcl2 is blocked by OA, a potent PP1 and PP2A inhibitor; 2) intracellular PP2A, but not PP1, co-localizes with Bcl2; 3) the purified PP2Ac catalytic subunit directly dephosphorylates Bcl2 in vitro in an OA-sensitive manner; 4) the purified PP2Ac catalytic subunit preferentially dephosphorylates Bcl2 in vitro compared with PP1 and PP2B; 5) reciprocal immunoprecipitation studies indicate a direct interaction between PP2A and hemagglutinin (HA)-Bcl2; and 6) treatment of factor-deprived cells with bryostatin 1 dramatically increases the association between PP2A and Bcl2. Increased association between Bcl2 and PP2A occurs 15 min after agonist stimulation when Bcl2 phosphorylation has peaked and immediately before dephosphorylation. An agonist-induced increased association of PP2A and Bcl2 fails to occur in cells expressing the inactive, phosphorylation-negative S70A Bcl2 mutant, which indicates that an intact Ser70 site is necessary and sufficient for the interaction to occur. Functional phosphorylation of Bcl2 at Ser70 is proposed to be a dynamic process regulated by the sequential action of an agonist-activated Bcl2 kinase and PP2A.
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PMID:Reversible phosphorylation of Bcl2 following interleukin 3 or bryostatin 1 is mediated by direct interaction with protein phosphatase 2A. 985 76

The Raf/MEK/MAP kinase cascade plays a critical role in transducing growth signals from activated cell surface receptors. Using deltaMEK1:ER, a conditionally-active form of MEK1, we demonstrate the ability of this dual specificity protein kinase to abrogate the cytokine-dependency of the human and murine hematopoietic cells lines TF-1, FDC-P1 and FL5.12. Cytokine-independent cells were obtained from TF-1, FDC-P1 and FL5.12 cells at frequencies of 2.5 x 10(-3), 5 x 10(-5) and 10(-7) respectively, indicating that not all cells expressing deltaMEK1:ER were factor-independent. In general, cells that were converted to a cytokine-independent phenotype displayed a higher level of MAP kinase activity in response to deltaMEK1:ER activation than those that remained cytokine-dependent. deltaME-K1:ER-responsive cells could be maintained long-term in the presence of beta-estradiol as well as the estrogen-receptor antagonist 4-Hydroxy-Tamoxifen and the anti-estrogen ICI 164383. Removal of hormone led to the rapid cessation of cell growth in a manner similar to that observed when cytokine is withdrawn from the parental cells. Treatment of deltaMEKI:ER-responsive cells with a specific and selective inhibitor, PD98059, prevented growth in response to beta-estradiol. GM-CSF mRNA transcripts were detected in the MEK1-responsive cells indicating that the activated deltaMEK1:ER may induce a pathway leading to autocrine proliferation. Treatment of MEK1-responsive cells with an anti-GM-CSF antibody, but not a control antibody, suppressed cell growth. The cell lines described here will be useful for elaborating the ability of the MAP kinase pathway to regulate cell proliferation in hematopoietic cells.
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PMID:A conditionally-active form of MEK1 results in autocrine tranformation of human and mouse hematopoietic cells. 1069 22

In this study, the abilities of constitutive and conditional forms of the three Raf kinases to abrogate the cytokine dependency of FDC-P1 cells were examined. The constitutively active forms (delta) of all three Raf kinases were fused to the hormone-binding domain of the estrogen receptor (ER), rendering their activities conditionally dependent upon exogenous beta-estradiol. The vast majority of deltaRaf:ER-infected FDC-P1 cells remained cytokine-dependent; however, cells were obtained at low frequency in which expression of deltaRaf:ER abrogated cytokine dependency. Isoform specific differences between the Raf kinases were observed as cytokine-independent cells were obtained more frequently from deltaA-Raf:ER than either deltaRaf-1:ER or deltaB-Raf:ER infected cells. To determine whether the regulatory phosphorylation sites in the Raf proteins were necessary for abrogation of cytokine dependency, they were changed by site-directed mutagenesis. Substitution with phenylalanine eliminated the transforming ability of the deltaB-Raf:ER and deltaRaf-1:ER kinases. However, a similar substitution in A-Raf did not extinguish its transforming activity. The activated Raf proteins induced essential downstream MEK1 activity as treatment with the MEK1 inhibitor, PD98059, suppressed Raf-mediated growth. Activated MAP kinases (ERK1 and ERK2) were detected in deltaRaf:ER-transformed cells, and their presence was dependent upon a functional MEK1 protein. The cytokine-independent phenotype required the continued activity of the deltaRaf:ER proteins as removal of beta-estradiol caused the cells to stop growing and undergo apoptosis. The Raf-responsive cells were found to express autocrine growth factors, which promoted their growth. Constitutive activation of the Raf-1 oncogene resulted in malignant transformation as cytokine-independent FDC-P1 cells infected with a retrovirus encoding an activated Raf-1 protein formed tumors upon injection of immunocompromised mice. In summary, Raf kinases can abrogate cytokine dependency, prevent apoptosis and induce the tumorigenicity of a certain subpopulation of FDC-P1 cells by a MEK1-dependent mechanism.
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PMID:Differential abilities of the Raf family of protein kinases to abrogate cytokine dependency and prevent apoptosis in murine hematopoietic cells by a MEK1-dependent mechanism. 1076 50

The Raf oncoprotein plays critical roles in the transmission of mitogenic signals from cytokine receptors to the nucleus. There are three Raf family members: A-Raf, B-Raf and Raf-1. Conditionally active forms of the Raf proteins were created by ligating N-terminal truncated activated forms to the estrogen-receptor (ER) hormone-binding domain resulting in beta-estradiol-inducible constructs. We introduced these chimeric deltaRaf:ER oncoproteins into the murine FDC-P1 hematopoietic cell line. Two different types of cells were recovered after drug selection in medium containing either cytokine or beta-estradiol: (1) cytokine-dependent cells that expressed the deltaRaf:ER oncoproteins; and (2) Raf-responsive cells that grew in response to the deltaRaf:ER oncoprotein. Depending upon the particular deltaRaf:ER oncoprotein, cytokine-dependent cells were recovered 10(3) to 10(5) times more frequently than Raf-responsive cells. To determine whether BCL2 could synergize with the deltaRaf:ER oncoproteins and increase the frequency of cytokine-independent cells, cytokine-dependent deltaRaf:ER-expressing cells were infected with either a BCL2 containing retrovirus or an empty retroviral vector. BCL2 overexpression, by itself, did not relieve cytokine dependency of the parental cell line. However, BCL2 overexpression increased the frequency of Raf-responsive cells approximately five- to 100-fold. Cytokine-dependent deltaRaf:ER-infected cells entered the G1 phase of the cell cycle after cytokine withdrawal and entered S phase only after cytokine addition. Raf-responsive deltaRaf:ER cells entered the G1 phase of the cell cycle after estrogen deprivation and re-entered the cell cycle after addition of either IL-3 or the estrogen receptor antagonist tamoxifen which activates the deltaRaf:ER constructs. Expression of the BCL2 oncoprotein often delayed the exit from the S and G2/M phases demonstrating the protective effects BCL2 provided to these Raf and BCL2 infected cells. The deltaRaf:ER cells expressed the deltaRaf:ER proteins and downstream MEK and ERK activities after beta-estradiol treatment. Raf-responsive cells that were also infected with BCL2 expressed higher levels of BCL2 than the cells that were not infected with BCL2. Thus BCL2 can synergize with the activated Raf in the abrogation of cytokine dependency of certain hematopoietic cells. These cells will be useful in furthering our understanding of the roles of the Raf and BCL2 oncoproteins in hematopoietic cell growth, cell cycle progression and prevention of apoptosis.
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PMID:Synergy between Raf and BCL2 in abrogating the cytokine dependency of hematopoietic cells. 1086 73

To investigate the functions of the different Raf genes in hematopoietic cell proliferation, the capacities of beta-estradiol-regulated Delta Raf:ER genes to induce cell cycle regulatory gene expression and cell cycle progression in FDC-P1 cells were examined. Raf activation increased the expression of Cdk2, Cdk4, cyclin A, cyclin D, cyclin E, p21(Cip1) and c-Myc and decreased the expression of p27(Kip1) which are associated with G(1) progression. However only the cell clones with moderate Raf activation, i.e. FD/Delta Raf-1:ER and FD/Delta A-Raf:ER, successfully underwent cell proliferation. The cell clones with the highest Delta Raf activity, FD/Delta B-Raf:ER, underwent apoptosis before cell proliferation. p21(Cip1) induced by Raf activation specifically bound with Cdk4/cyclin D complexes but not Cdk2/cyclin E complexes and this binding was associated with the increased Cdk4 activity. However, no binding of p27(Kip1) with either Cdk2/cyclin E or Cdk4/cyclin D was observed. Thus Raf mediated growth was associated with elevated p21(Cip1) expression, which may specifically bind with and activate Cdk4/cyclin D complexes and with decreased p27(Kip1) expression.
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PMID:P21(Cip1) induced by Raf is associated with increased Cdk4 activity in hematopoietic cells. 1146 16

The PI3K/Akt and Raf/MEK/ERK signal transduction cascades are pivotal in transmitting signals from membrane receptors to downstream targets that regulate apoptosis, gene expression, and cell growth. The abilities of activated PI3K, Akt, Raf, and MEK proteins to abrogate the cytokine dependence of three different hematopoietic cell lines were determined. Activated PI3K or Akt expression by themselves did not efficiently annul cytokine dependence. Raf and MEK could abrogate the cytokine dependence of murine FDC-PI and human TF-1 cells; however, the frequency of transformation was dependent on the particular oncogene examined, as more factor-independent cells were isolated after infection with activated retroviruses encoding A-Raf or Raf-1 than were with MEK1 or B-Raf. Cytokine-independent deltaRaf-1-infected cells formed tumors on injection into immunocompromised mice, whereas cytokine-dependent cell lines did not, demonstrating the oncogenic effects of activation of the Raf/MEK/ERK pathway. Overexpression of the antiapoptotic Bcl-2 protein synergized with activation of the Raf/MEK/ERK cascade and increased the efficiency of transformation of FDC-PI and TF-1 cells. In contrast to the results observed with FDC-P1 and TF-I cells, the activated Raf genes did not relieve the cytokine dependence of murine FL5.12 cells. The abilities of the Raf and PI3K pathways to interact and annul the cytokine dependence of FL5.12 cells were determined. The combination of Raf and either PI3K or Akt expression relieved cytokine dependence of some FL5.12 cells, and the efficiency of transformation could be enhanced further by Bcl-2 or Bcl-XL overexpression. Thus, the antiapoptotic PI3K/Akt and Bcl-2/Bcl-XL proteins can interact with the growth-promoting Raf/MEK/ERK pathway and annul the cytokine dependence of certain hematopoietic cells.
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PMID:Interactions between the PI3K and Raf signaling pathways can result in the transformation of hematopoietic cells. 1153 Oct 15

The IFN regulatory factor-2 (IRF-2) oncoprotein controls the cell cycle-dependent expression of histone H4 genes during S phase and may function as a component of an E2F-independent mechanism to regulate cell growth. To investigate the role of IRF-2 in control of cell proliferation, we have constructed a stable FDC-P1 cell line (F2) in which expression of IRF-2 is doxycycline (DOX)-inducible, and a control cell line (F0). Both the F2 and F0 cell lines were synchronized in the G1 phase by isoleucine deprivation, and IRF-2 was induced by DOX on release of cells from the cell cycle block. Flow cytometric analyses indicated that forced expression of IRF-2 has limited effects on cell cycle progression before the first mitosis. However, continued cell growth in the presence of elevated IRF-2 levels results in polyploidy (>4n) or genomic disintegration (<2n) and cell death. Western blot analyses revealed that the levels of the cell cycle regulatory proteins cyclin B1 and the cyclin-dependent kinase (CDK)-inhibitory protein p27 are selectively increased. These changes occur concomitant with a significant elevation in the levels of the FAS-L protein, which is the ligand of the FAS (Apo1/CD95) receptor. We also found a subtle change in the ratio of the apoptosis-promoting Bax protein and the antiapoptotic Bcl-2 protein. Hence, IRF-2 induces a cell death response involving the Fas/FasL apoptotic pathway in FDC-P1 cells. Our data suggest that the IRF-2 oncoprotein regulates a critical cell cycle checkpoint that controls progression through G2 and mitosis in FDC-P1 hematopoietic progenitor cells.
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PMID:Forced expression of the interferon regulatory factor 2 oncoprotein causes polyploidy and cell death in FDC-P1 myeloid hematopoietic progenitor cells. 1198 Jun 42


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