Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chaperone-enriched domains are formed in the nuclei of cells lytically infected with herpes simplex virus type 1 (HSV-1). These domains, called VICE, for virus induced chaperone enriched, contain Hsc70, Hsp70, Hsp40, Hsp90, polyubiquitinated proteins, and components of the proteasome machinery. Accumulating evidence indicates that these sites may be utilized during infection to sequester misfolded, modified, or otherwise unwanted proteins away from viral replication compartments, sites of robust transcription, DNA synthesis, and capsid maturation. To further explore the role of cellular chaperones and VICE domains during HSV-1 infection, we have analyzed the cytoprotective chaperone Hsp27. Here we present evidence that Hsp27, which is known to possess several antioxidant functions, is rapidly reorganized and modified at early stages in response to HSV-1 infection and signaling from the mitogen-activated protein kinase p38. Immunofluorescence analysis and fractionation experiments reveal disparate subcellular localizations of nonphosphorylated and phosphorylated forms of Hsp27 during wild-type HSV-1 infection. Unmodified forms of Hsp27 are localized in nuclear foci that are outside of replication compartments, adjacent to VICE domains, and in the cytoplasm. Conversely, we find that phosphorylated forms of Hsp27 are localized exclusively in the cytoplasm. Last, in cells depleted of all forms of Hsp27, virus replication is significantly reduced.
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PMID:Modification and reorganization of the cytoprotective cellular chaperone Hsp27 during herpes simplex virus type 1 infection. 1958 60

Multiple signaling pathways via insulin receptor substrate-1 and -2 play crucial roles in health, diseases, and therapeutics (i.e., longevity, tumorigenesis, and neuroprotection). The 90-kDa heat-shock protein (Hsp90) is an emerging target molecule of therapeutics, Hsp90 inhibitors being promising against various diseases (e.g., cancer, brain and cardiac ischemia, and neurodegenerative diseases). Much remains, however, unknown whether Hsp90 could regulate insulin receptor substrate-1 and -2 signaling pathways. In cultured bovine adrenal chromaffin cells, we observed that 24-h treatment with 1 microM geldanamycin (an inhibitor of Hsp90) decreased insulin receptor substrate-1 level, while increasing insulin receptor substrate-2 level; besides, geldanamycin lowered phosphoinositide 3-kinase, phosphoinositide-dependent kinase-1, Akt, glycogen synthase kinase-3beta, and Raf-1 levels, without changing extracellular signal-regulated kinase and its upstream kinase levels. Chronic (>or=12h) treatment with 0.1-10 microM Hsp90 inhibitor (geldanamycin, 17-allylamino-17-demethoxy-geldanamycin, herbimycin A, and radicicol) decreased insulin receptor substrate-1 level by approximately 66%, while increasing insulin receptor substrate-2 level by approximately 160%. These effects of geldanamycin (IC(50) 155 nM, EC(50) 177 nM) and 17-allylamino-17-demethoxy-geldanamycin (IC(50) 310 nM, EC(50) 260 nM) were time- and concentration-dependent. Geldanamycin-induced decrease of insulin receptor substrate-1 was attenuated by lactacystin, beta-lactone or MG132 (proteasome inhibitor), but not by calpastatin (calpain inhibitor) or leupeptin (lysosome inhibitor); geldanamycin did not affect heteroprotein complex formation between insulin receptor substrate-1 or -2 and Hsp90. Geldanamycin-induced increase of insulin receptor substrate-2 was prevented by cycloheximide or actinomycin D. Geldanamycin lowered insulin receptor substrate-1 mRNA level by approximately 39%, while raising insulin receptor substrate-2 mRNA level by approximately 109% between 3 and 24h, without changing the stability of insulin receptor substrate-1 and -2 mRNAs. Nuclear run-on assay revealed that geldanamycin retarded insulin receptor substrate-1 gene transcription by 42%, while accelerating insulin receptor substrate-2 gene transcription by 41%. Hsp90 inhibitors oppositely altered insulin receptor substrate-1 and -2 levels via proteasomal degradation and gene transcription.
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PMID:Distinct regulation of insulin receptor substrate-1 and -2 by 90-kDa heat-shock protein in adrenal chromaffin cells. 1973 90

In mammals, CpG mediated immune activation is initiated through toll-like receptor (TLR) 9 and Hsp90 via activation of MAPK/ERK and PI3K/AKT pathways. However, in the absence of TLR9 ortholog in chicken genome, the role of Hsp90 and kinase (MAPK/ERK and PI3K/AKT) pathways in initiating CpG ODN(2007) induced immune activation in chicken is not clear. Using electrophoretic mobility shift assay (EMSA) and selective inhibitors of signal transduction pathways, we determined the role of these pathways in the production of Th1 cytokines/chemokines and nitric oxide (NO) in CpG ODN(2007) treated avian macrophage cells. Hsp90alpha but not Hsp90beta is bound to CpG ODN(2007). Inhibition of Hsp90 with geldanamycin resulted in the inactivation of MAPK/ERK and PI3K/AKT pathways leading to significantly reduced levels of IFN-gamma, IL-6 and NO mRNAs in CpG ODN(2007) stimulated cells. Moreover, inhibition of ERK1/2 and PI3/AKT kinase pathways with PD985009 and LY294002, respectively, suppresses the phosphorylation of ERK2 and AKT leading to the production of decreased amounts of IFN-gamma, IL-6 and NO mRNAs in CpG ODN(2007) stimulated cells. Our results demonstrate that binding of CpG ODN(2007) to Hsp90 induces activation of ERK2 and AKT phosphorylation leading to the production of high levels of IFN-gamma, IL-6, MIP-3alpha and nitric oxide (NO). In contrast to mammals, our results suggest that Hsp90alpha but not Hsp90beta binds with the CpG ODN(2007) and may play a major role in CpG ODN(2007) induced immunoactivation in avian macrophage cells. To our knowledge, this is the first report evaluating the involvement of Hsp90 and kinase (MAPK/ERK and PI3K/AKT) pathways in CpG mediated immunostimulation in avian macrophage cells.
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PMID:Role of Hsp90 in CpG ODN mediated immunostimulation in avian macrophages. 2009 33

Resistance to the Bcr-Abl inhibitors approved for the treatment of chronic myeloid leukaemia (CML) may arise from different mechanisms, including Bcr-Abl amino acid mutations, gene amplification and mechanisms independent of Bcr-Abl. The T315I mutation at the gatekeeper residue is very frequent in advanced phases of the disease and is one of the main causes of resistance, disrupting important contact points between the inhibitors and the enzyme. Different strategies have been implemented to overcome this resistance, including the synthesis of new Bcr-Abl ATPcompetitive or non-ATP-competitive inhibitors, dual Aurora/Bcr-Abl inhibitors and multi-targeted kinase inhibitors. An alternative approach is the use of other compounds that do not bind directly to the Bcr-Abl protein; instead, these molecules act on several downstream pathways, regulated by or linked in different ways to Bcr-Abl, that lead to the malignant transformation of the cells. For this reason, farnesyl transferase inhibitors, MAPK inhibitors, Rac guanosine triphosphatase inhibitors, PI3K inhibitors, JAK inhibitors, Hsp90 inhibitors, mTOR inhibitors, PP2A activators and apoptosis inducers have been tested, alone or in combination with ATP-competitive inhibitors, against CML cell lines. This review discusses compounds that act on Bcr-Abl or different cell pathways and reports on the molecules active against the T315I mutation, particularly the most recent findings in this field. New molecules that are claimed by recent patents to be active on this mutation are also reported. When possible, the review will focus on medicinal chemistry in terms of chemical structure, mechanism of action and structure-activity relationships.
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PMID:New opportunities to treat the T315I-Bcr-Abl mutant in chronic myeloid leukaemia: tyrosine kinase inhibitors and molecules that act by alternative mechanisms. 2016 37

The Kaposi's sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi's sarcoma (KS), an important cause of morbidity and mortality in immunocompromised patients. KSHV interaction with the cell membrane triggers activation of specific intracellular signal transduction pathways to facilitate virus entry, nuclear trafficking, and ultimately viral oncogene expression. Extracellular heat shock protein 90 localizes to the cell surface (csHsp90) and facilitates signal transduction in cancer cell lines, but whether csHsp90 assists in the coordination of KSHV gene expression through these or other mechanisms is unknown. Using a recently characterized non-permeable inhibitor specifically targeting csHsp90 and Hsp90-specific antibodies, we show that csHsp90 inhibition suppresses KSHV gene expression during de novo infection, and that this effect is mediated largely through the inhibition of mitogen-activated protein kinase (MAPK) activation by KSHV. Moreover, we show that targeting csHsp90 reduces constitutive MAPK expression and the release of infectious viral particles by patient-derived, KSHV-infected primary effusion lymphoma cells. These data suggest that csHsp90 serves as an important co-factor for KSHV-initiated MAPK activation and provide proof-of-concept for the potential benefit of targeting csHsp90 for the treatment or prevention of KSHV-associated illnesses.
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PMID:Extracellular Hsp90 serves as a co-factor for MAPK activation and latent viral gene expression during de novo infection by KSHV. 2045 Dec 33

The involvement of heat shock protein Hsp90 in pro-inflammatory response in male NMRI mice under conditions of acute toxic stress, caused by lipopolysaccharide from Gram negative bacteria, was studied using geldanamycin, a specific blocker of the activity of this protein. It is shown that the introduction of geldanamycin lowers total intoxication of the organism upon acute toxic stress caused by endotoxin. Thus, a decrease in cytokine TNF-alpha, IFN-gamma, IL-1, and IL-10 concentrations in blood serum of the geldanamycin-treated animals with acute toxic stress was found along with normalization of functional activity of nitric oxide producing peritoneal macrophages. Studying expression of receptor protein Tlr-4 as well of proteins of two signal cascades, NF-kappaB and SAPK/JNK, has shown that mechanisms of the geldanamycin protective effect are realized at the level of inhibition of Tlr-4 receptor expression, which provides for endotoxin-to-cell binding, and due to lowering the endotoxin-stimulated activation of signal cascades NF-kappaB and SAPK/JNK. The results suggest Hsp90 might be a therapeutic target in diseases accompanied by acute toxic stress.
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PMID:Role of heat shock protein hsp90 in formation of protective reactions in acute toxic stress. 2063 61

The Ras/Raf/MEK/ERK signaling has been implicated in uncontrolled cell proliferation and tumor progression in pancreatic cancer. The purpose of this study is to evaluate the antitumor activity of MEK inhibitor U0126 in combination with Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) in pancreatic cancer cells. Western blotting showed that 17-AAG caused a 2- to 3-fold transient activation of MEK/ERK signaling in pancreatic cancer cells. The activation sustained for 6 h before phospho-ERK (p-ERK) destabilization. The selective MEK inhibitor U0126 completely abolished 17-AAG induced ERK1/2 activation and resulted in more than 80% of phospho-ERK degradation after only 15 min treatment. Moreover, U0126 had complementary effect on 17-AAG regulated oncogenic and cell cycle related proteins. Although 17-AAG downregulated cyclin D1, cyclin E, CDK4 and CDK6, it led to cyclin A and CDK2 accumulation, which was reversed by the addition of U0126. Antiproliferation assay showed that combination of U0126 and 17-AAG resulted in synergistic cytotoxic effect. More importantly, 17-AAG alone only exhibited moderate inhibition of cell migration in vitro, while addition of U0126 dramatically enhanced the inhibitory effect by 2- to 5-fold. Taken together, these data demonstrate that MEK inhibitor U0126 potentiates the activity of Hsp90 inhibitor 17-AAG against pancreatic cancer cells. The combination of Hsp90 and MEK inhibition could provide a promising avenue for the treatment of pancreatic cancer.
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PMID:MEK inhibition potentiates the activity of Hsp90 inhibitor 17-AAG against pancreatic cancer cells. 2066 73

The function of protein phosphatases with EF-hand domains (PPEF) in mammals is not known. Large-scale expression profiling experiments suggest that PPEF expression may correlate with stress protective responses, cell survival, growth, proliferation, or neoplastic transformation. Apoptosis signal regulating kinase-1 (ASK1) is a MAP kinase kinase kinase implicated in cancer, cardiovascular and neurodegenerative diseases. ASK1 is activated by oxidative stress and induces pro-apoptotic or inflammatory signalling, largely via sustained activation of MAP kinases p38 and/or JNK. We identify human PPEF2 as a novel interacting partner and a negative regulator of ASK1. In COS-7 or HEK 293A cells treated with H(2)O(2), expression of PPEF2 abrogated sustained activation of p38 and one of the JNK p46 isoforms, and prevented ASK1-dependent caspase-3 cleavage and activation. PPEF2 efficiently suppressed H(2)O(2)-induced activation of ASK1. Overexpessed as well as endogenous ASK1 co-immunoprecipitated with PPEF2. PPEF2 was considerably more potent both as a suppressor of ASK1 activation and as its interacting partner as compared to protein phosphatase 5 (PP5), a well-known negative regulator of ASK1. PPEF2 was found to form complexes with endogenous Hsp70 and to a lesser extent Hsp90, which are also known interacting partners of PP5. These data identify, for the first time, a possible downstream signalling partner of a mammalian PPEF phosphatase, and suggest that, despite structural divergence, PPEF and PP5 phosphatases may share common interacting partners and functions.
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PMID:Protein phosphatase with EF-hand domains 2 (PPEF2) is a potent negative regulator of apoptosis signal regulating kinase-1 (ASK1). 2067 65

The advent of drugs targeting tumor-associated prosurvival alterations of cancer cells has changed the interest of antitumor drug development from cytotoxic drugs to target-specific agents. Although single-agent therapy with molecularly targeted agents has shown limited success in tumor growth control, a promising strategy is represented by the development of rational combinations of target-specific agents and conventional antitumor drugs. Activation of survival/antiapoptotic pathways is a common feature of cancer cells that converge in the development of cellular resistance to cytotoxic agents. The survival pathways implicated in cellular response to drug treatment are primarily PI3K/Akt and Ras/MAPK, which also mediate the signalling activated by growth factors and play a role in the regulation of critical processes including cell proliferation, metabolism, apoptosis and angiogenesis. Inhibitors of PI3K, Akt and mTOR have been shown to sensitize selected tumor cells to cytotoxic drugs through multiple downstream effects. Moreover, the MAPK pathway, also implicated in the regulation of gene expression in response to stress stimuli, can interfere with the chemotherapy-induced proapoptotic signals. Targeting Hsp90, which acts as a molecular chaperone for survival factors including Akt, may have the potential advantage to simultaneously block multiple oncogenic pathways. Overall, the available evidence supports the interest of rationally designed approaches to enhance the efficacy of conventional antitumor treatments through the inhibition of survival pathways and the notion that the concomitant targeting of multiple pathways may be a successful strategy to deal with tumor heterogeneity and to overcome drug resistance of tumor cells.
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PMID:Modulation of cell sensitivity to antitumor agents by targeting survival pathways. 2068 50

Hsp90 facilitates the maturation and stability of numerous oncoproteins, including HER2. The aim of this study was to assess the antitumor activity of the Hsp90 inhibitor IPI-504 in trastuzumab-resistant, HER2-overexpressing breast cancer cells. Therapy with trastuzumab, IPI-504, and the combination of trastuzumab and IPI-504 was evaluated in trastuzumab-sensitive and trastuzumab-resistant cells. Inhibition of protein targets, cell proliferation, and tumor growth was assessed in vitro and in xenograft models. IPI-504 inhibited proliferation of both trastuzumab-sensitive and trastuzumab-resistant cells. Administration of IPI-504 markedly reduced total levels of HER2 and Akt, as well as phosphorylated Akt and mitogen-activated protein kinase (MAPK), to an equal extent in trastuzumab-sensitive and trastuzumab-resistant cells. IPI-504, used as single agent or in combination with trastuzumab, also inhibited in vivo the growth of both trastuzumab-sensitive and -resistant tumor xenografts. As a mechanism for the observed antitumor activity, IPI-504 resulted in a marked decrease in the levels of HER2, Akt, p-Akt, and p-MAPK in trastuzumab-resistant xenografts as early as 12 hours after a single dose of IPI-504. IPI-504-mediated Hsp90 inhibition may represent a novel therapeutic approach in trastuzumab refractory HER2-positive breast cancer.
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PMID:Antitumor activity of the Hsp90 inhibitor IPI-504 in HER2-positive trastuzumab-resistant breast cancer. 2138 49


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