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)

Posttranslational modification of target substrates underlies biological processes through activation/inactivation of signaling cascades. To concurrently identify the phosphoprotein substrates associated with cardiac beta-adrenergic signaling, the mouse myocyte phosphoproteome was analyzed using 2-D gel electrophoresis in combination with 32P autoradiography. Phosphoprotein spots, detected by silver staining, were identified using MALDI-TOF mass spectrometry in conjunction with computer-assisted protein spot matching. Stimulation with isoproterenol (1 micromol/L for 5 minutes) was associated with maximal increases in myocyte contractile parameters, and significant stimulation of the phosphorylation of troponin I (190+/-23%) and succinyl CoA synthetase (160+/-16%), whereas the phosphorylation of pyruvate dehydrogenase (48+/-10%), NADH-ubiquinone oxidoreductase (46+/-6%), heat shock protein 27 (18+/-3%), alphaB-crystallin (20+/-3%), and an unidentified 26-kDa protein (29+/-7%) was significantly decreased, compared with unstimulated cells (100%). After sustained (30 minutes) stimulation with isoproterenol, only the alterations in the phosphorylation levels of troponin I and NADH-ubiquinone oxidoreductase were maintained and de novo phosphorylation of a phosphoprotein (approximately 20 kDa and pI 5.5) was observed. The tryptic peptide fragments of this phosphoprotein were sequenced using postsource decay mass spectrometry, and the protein was subsequently cloned and designated as p20, based on its high sequence homology with rat and human skeletal p20. The mouse cardiac p20 contains the conserved domain sequences for heat shock proteins, and the RRAS consensus sequence for cAMP-PKA substrates. LC-MS/MS phosphorylation mapping confirmed phosphorylation of Ser16 in p20 on beta-agonist stimulation. Adenoviral gene transfer of p20 was associated with significant increases in contractility and Ca transient peak in adult rat cardiomyocytes, suggesting an important role of p20 in cardiac function. These findings suggest that cardiomyocytes undergo significant posttranslational modification via phosphorylation in a multitude of proteins to dynamically fine-tune cardiac responses to beta-adrenergic signaling.
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PMID:Phosphoproteome analysis of cardiomyocytes subjected to beta-adrenergic stimulation: identification and characterization of a cardiac heat shock protein p20. 1516 17

Endorepellin, the COOH-terminal domain of the heparan sulfate proteoglycan perlecan, inhibits several aspects of angiogenesis. We provide evidence for a novel biological axis that links a soluble fragment of perlecan protein core to the major cell surface receptor for collagen I, alpha2beta1 integrin, and provide an initial investigation of the intracellular signaling events that lead to endorepellin antiangiogenic activity. The interaction between endorepellin and alpha2beta1 integrin triggers a unique signaling pathway that causes an increase in the second messenger cAMP; activation of two proximal kinases, protein kinase A and focal adhesion kinase; transient activation of p38 mitogen-activated protein kinase and heat shock protein 27, followed by a rapid down-regulation of the latter two proteins; and ultimately disassembly of actin stress fibers and focal adhesions. The end result is a profound block of endothelial cell migration and angiogenesis. Because perlecan is present in both endothelial and smooth muscle cell basement membranes, proteolytic activity during the initial stages of angiogenesis could liberate antiangiogenic fragments from blood vessels' walls, including endorepellin.
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PMID:Endorepellin causes endothelial cell disassembly of actin cytoskeleton and focal adhesions through alpha2beta1 integrin. 1524 May 72

Skeletal disorders and neural tube closure defects represent clinically significant human malformations. The signaling networks regulating normal skeletal patterning and neurulation are largely unknown. Targeted mutation of the active site lysine of MEK kinase 4 (MEKK4) produces a kinase-inactive MEKK4 protein (MEKK4(K1361R)). Embryos homozygous for this mutation die at birth as a result of skeletal malformations and neural tube defects. Hindbrains of exencephalic MEKK4(K1361R) embryos show a striking increase in neuroepithelial cell apoptosis and a dramatic loss of phosphorylation of MKK3 and -6, mitogen-activated protein kinase kinases (MKKs) regulated by MEKK4 in the p38 pathway. Phosphorylation of MAPK-activated protein kinase 2, a p38 substrate, is also inhibited, demonstrating a loss of p38 activity in MEKK4(K1361R) embryos. In contrast, the MEK1/2-extracellular signal-regulated kinase 1 (ERK1)/ERK2 and MKK4-Jun N-terminal protein kinase pathways were unaffected. The p38 pathway has been shown to regulate the phosphorylation and expression of the small heat shock protein HSP27. Compared to the wild type, MEKK4(K1361R) fibroblasts showed significantly reduced phosphorylation of p38 and HSP27, with a corresponding heat shock-induced instability of the actin cytoskeleton. Together, these data demonstrate MEKK4 regulation of p38 and that substrates downstream of p38 control cellular homeostasis. The findings are the first demonstration that MEKK4-regulated p38 activity is critical for neurulation.
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PMID:Ablation of MEKK4 kinase activity causes neurulation and skeletal patterning defects in the mouse embryo. 1619 73

Cell migration is critical for many processes, such as angiogenesis, inflammation, development and wound healing, and is also involved in tumour progression and metastasis. Here we show that CXCL12, complement factor 5a (C5a), hepatocyte growth factor (HGF) and platelet-derived growth factor (PDGF)-BB, which stimulate cell migration, also activate p38alpha MAPK. Pharmacological inhibition of this protein kinase with SB 203580 or BIRB 0796, or the genetic ablation of p38alpha MAPK, blocked cell migration induced by the aforementioned chemo-attractants. Macrophages from mice lacking one or more of the other p38 MAPK isoforms showed normal cell migration in response to C5a. We also show that the activation of p38alpha MAPK in response to CXCL12 requires the p21-activated protein kinases (PAK)-1 and PAK-2. MAPKAP-K2 is a protein kinase that is activated by p38alpha MAPK. Reducing its expression using RNA interference blocked CXCL12-induced HeLa cell migration, while macrophages from mice that do not express MAPKAP-K2 failed to migrate in response to C5a. Moreover, RNA interference against the small heat shock protein 27 (HSP27), a physiological substrate of MAPKAP-K2, blocked the CXCL12-induced cell migration. These results demonstrate a general and essential role of the PAK-p38alpha MAPK-MAPKAP-K2-HSP27 signalling pathway in mediating the effects of chemotactic stimuli on cell migration.
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PMID:CXCL12 and C5a trigger cell migration via a PAK1/2-p38alpha MAPK-MAPKAP-K2-HSP27 pathway. 1657 78

We showed previously that activation of A(1) adenosine receptors (AR) protects against renal ischemia-reperfusion (IR) injury in rats and mice. In the heart, transient A(1)AR activation produces biphasic protective effects: acute protection wanes after several hours but protective effects return 24-72 h later (second window of protection). In this study, we determined whether A(1)AR activation produces delayed renal protection and elucidated the mechanisms of acute and delayed renal protection. A(1)AR wild-type mice were subjected to 30-min renal ischemia and 24 h of reperfusion to produce acute renal failure. Pretreatment with a selective A(1)AR agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA; 0.1 mg/kg bolus ip) either 15 min or 24 h before renal ischemia protected against renal IR injury and reduced renal corticomedullary necrosis, apoptosis, and inflammation. Transient A(1)AR activation led to phosphorylation of extracellular signal-regulated protein kinase mitogen-activated protein kinase (ERK MAPK), Akt, and heat shock protein 27 (HSP27). Moreover, induction of HSP27 and Akt occurred with CCPA treatment. Inhibition of PKC with chelerythrine prevented acute but not delayed renal protection with A(1)AR activation. Moreover, deletion of PI3Kgamma or inhibition of Akt, but not inhibition of ERK, prevented delayed and acute renal protection with A(1)AR activation. Inhibition of G(i/o) with pertussis toxin obliterated both acute and delayed A(1)AR-mediated renal protection. In contrast to renal protection with delayed ischemic preconditioning, nitric oxide synthase activity was not induced with delayed A(1)AR-mediated renal protection. Therefore, transient activation of renal A(1)AR led to acute as well as delayed protective effects against renal IR injury via distinct signaling pathways.
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PMID:Acute and delayed renal protection against renal ischemia and reperfusion injury with A1 adenosine receptors. 1792 14

We previously reported that prostaglandin D2 (PGD2) stimulates heat shock protein 27 (HSP27) induction through p38 mitogen-activated protein (MAP) kinase, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) and p44/p42 MAP kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether (-)-epigallocatechin gallate (EGCG), the major polyphenol found in green tea, affects the induction of HSP27 in these cells and the mechanism. EGCG significantly reduced the HSP27 induction stimulated by PGD2 without affecting the levels of HSP70. The PGD2-induced phosphorylation of p38 MAP kinase or SAPK/JNK was not affected by EGCG. On the contrary, EGCG markedly suppressed the PGD2-induced phosphorylation of p44/p42 MAP kinase and MEK1/2. However, the PGD2-induced phosphorylation of Raf-1 was not inhibited by EGCG. These results strongly suggest that EGCG suppresses the PGD2-stimulated induction of HSP27 at the point between Raf-1 and MEK1/2 in osteoblasts.
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PMID:(-)-epigallocatechin gallate inhibits prostaglandin D2-stimulated HSP27 induction via suppression of the p44/p42 MAP kinase pathway in osteoblasts. 1794 62

Aging is associated with an increase in insulin resistance in skeletal muscle, yet the underlying mechanism is not well established. We hypothesize that with aging, a chronic increase in stress kinase activation, coupled with a decrease in oxidative capacity, leads to insulin resistance in skeletal muscle. In aged (24 mo old) and young (3 mo old) Fischer 344 rats, 2-deoxyglucose uptake and insulin signaling [as measured by phosphorylation of insulin receptor substrate-1 (IRS-1), Akt (protein kinase B), and Akt substrate of 160 kDa (AS160)] decreased significantly with age. Activation of, c-Jun NH(2)-terminal kinase (JNK), glycogen serine kinase-3beta (GSK-3beta), and degradation of IkappaBalpha by the upstream inhibitor of kappa B kinase (IKKbeta), as measured by Western blot analysis, were increased with age in both soleus and epitrochlearis (Epi) muscles. However, much higher activation of these kinases in Epi muscles from young rats compared with soleus results in a greater effect of these kinases on insulin signaling in fast-twitch muscle with age. Heat shock protein (HSP) 72 expression and phosphorylation of HSP25 were higher in soleus compared with Epi muscles, and both parameters decreased with age. Age and fiber type differences in cytochrome oxidase activity are consistent with observed changes in HSP expression and activation. Our results demonstrate a significant difference in the ability of slow-twitch and fast-twitch muscles to respond to insulin and regulate glucose with age. A greater constitutive HSP expression and lower stress kinase activation may account for the ability of slow-twitch muscles to preserve the capacity to respond to insulin and maintain glucose homeostasis with age.
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PMID:Age-related differences in skeletal muscle insulin signaling: the role of stress kinases and heat shock proteins. 1859 80

Formation of heterooligomeric complexes of human small heat shock proteins (sHsp) HspB6 (Hsp20) and HspB1 (Hsp27) was analyzed by means of native gel electrophoresis, analytical ultracentrifugation, chemical cross-linking and size-exclusion chromatography. HspB6 and HspB1 form at least two different complexes with apparent molecular masses 100-150 and 250-300 kDa, and formation of heterooligomeric complexes is temperature dependent. These complexes are highly mobile, easily exchange their subunits and are interconvertible. The stoichiometry of HspB1 and HspB6 in both complexes is close to 1/1 and smaller complexes are predominantly formed at low, whereas larger complexes are predominantly formed at high protein concentration. Formation of heterooligomeric complexes does not affect the chaperone-like activity of HspB1 and HspB6 if insulin or skeletal muscle F-actin was used as model protein substrates. After formation of heterooligomeric complexes the wild type HspB1 inhibits the rate of phosphorylation of HspB6 by cAMP-dependent protein kinase. The 3D mutant mimicking phosphorylation of HspB1 also forms heterooligomeric complexes with HspB6, but is ineffective in inhibition of HspB6 phosphorylation. Inside of heterooligomeric complexes HspB6 inhibits phosphorylation of HspB1 by MAPKAP2 kinase. Thus, in heterooligomeric complexes HspB6 and HspB1 mutually affect the structure of each other and formation of heterooligomeric complexes might influence diverse processes depending on small heat shock proteins.
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PMID:Heterooligomeric complexes formed by human small heat shock proteins HspB1 (Hsp27) and HspB6 (Hsp20). 1910 Aug 70

Cardiac dysfunction is a major consequence of septic shock and may be responsible for the high mortality of sepsis. We have reported that transgenic mice with cardiac-specific overexpression of heat shock protein 27 (Hsp27 Tg) exhibited the protection against doxorubicin-induced cardiac dysfunction. We hypothesized that overexpression of Hsp27 will attenuate cardiac dysfunction during endotoxemia. Hsp27 Tg and age-matched wild-type (WT) mice were injected with LPS. Cardiac function was evaluated by echocardiography, survival rate was carefully monitored, and activities of signaling pathways were determined by immunoblot. LPS administration significantly decreased cardiac function in WT mice. In Hsp27 Tg mice, LPS-induced cardiac dysfunction was significantly attenuated as evidenced by increased ejection fraction (27.3%) and fractional shortening (37.1%), respectively, compared with LPS-treated WT mice. Heat shock protein 27 Tg mice were more resistant to LPS-induced mortality than WT. The levels of phospho-Akt and phospho-glycogen synthase kinase 3beta (phospho-GSK-3beta) in the myocardium were significantly increased in Hsp27 Tg mice compared with WT after LPS administration. Nuclear factor kappaB-binding activity was significantly decreased in Hsp27 Tg mice compared with WT mice after LPS challenge. Similar results were observed in in vitro studies using Hsp27-transfected rat cardiomyoblasts. Importantly, phosphoinositide 3-kinase inhibition abolished the protective effect of Hsp27 in LPS-induced cardiac dysfunction and mortality of endotoxemia. Our results suggest that Hsp27 plays an important role in attenuation of cardiac dysfunction and mortality in endotoxemia and that the mechanisms of the protection may involve activation of the PI3K/Akt signaling pathway.
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PMID:Cardiac-specific expression of heat shock protein 27 attenuated endotoxin-induced cardiac dysfunction and mortality in mice through a PI3K/Akt-dependent mechanism. 1910 22

Mitogen-activated protein kinase (MAPK) pathways can play a role in F-actin dynamics. In particular, the p38 MAPK/MAPK-activated protein kinase 2 (MK2)/heat shock protein 27 (Hsp27) pathway is involved in F-actin alternations. Previously, we showed that MK5 is implicated in F-actin rearrangement induced by the cAMP/cAMP-dependent protein kinase pathway in PC12 cells, while others found Hsp27 to be a good in vitro MK5 substrate. Here we demonstrate that MK5 can specifically interact with Hsp27 in vivo and can induce phosphorylation at serine residues 78 and 82 in cells. siRNA-mediated depletion of Hsp27 protein levels, as well as overexpression of the non-phosphorylatable Hsp27-3A mutant prevented forskolin-induced F-actin reorganization. While ectopic expression of a constitutive active MK5 mutant was sufficient to induce F-actin rearrangement in PC12 cells, co-expression of Hsp27-3A could ablate this process. Our results imply that MK5 is involved in Hsp27-controlled F-actin dynamics in response to activation of the cAMP-dependent protein kinase pathway. These findings render the MK5/Hsp27 connection into a putative therapeutic target for conditions with aberrant Hsp27 phosphorylation such as metastasis, cardiovascular diseases, muscle atrophy, autoimmune skin disease and neuropathology.
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PMID:PKA-induced F-actin rearrangement requires phosphorylation of Hsp27 by the MAPKAP kinase MK5. 1916 25


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