Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P51812 (mitogen-activated protein)
 10,636 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interaction between angiotensin II, which binds a G-protein-coupled receptor, and insulin, a ligand for receptor tyrosine kinase, was examined in renal proximal tubular epithelial cells. Augmented protein translation by insulin involves activation of eukaryotic initiation factor 4E (eIF4E) which follows the release of the factor from a heterodimeric complex by phosphorylation of its binding protein, 4E-BP1. Angiotensin II (1 nM) or insulin (1 nM) individually stimulated 4E-BP1 phosphorylation. However, pre-incubation with angiotensin II abrogated insulin-induced phosphorylation of 4E-BP1, resulting in persistent binding to eIF4E. Although angiotensin II and insulin individually activated phosphoinositide 3-kinase and extracellular signal-regulated kinase (ERK)-1/-2-type mitogen-activated protein (MAP) kinase, pre-incubation with angiotensin II abolished insulin-induced stimulation of these kinases, suggesting more proximal events in insulin signalling may be intercepted. Pretreatment with angiotensin II markedly inhibited insulin-stimulated tyrosine phosphorylation of insulin-receptor beta-chain and insulin-receptor substrate 1. Losartan prevented angiotensin II inhibition of insulin-induced ERK-1/-2-type MAP kinase activation and 4E-BP1 phosphorylation, suggesting mediation of the effect of angiotensin II by its type 1 receptor. Insulin-stimulated de novo protein synthesis was also abolished by pre-incubation with angiotensin II. These data show that angiotensin II inhibits 4E-BP1 phosphorylation and stimulation of protein synthesis induced by insulin by interfering with proximal events in insulin signalling. Our data provide a mechanistic basis for insulin insensitivity induced by angiotensin II.
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PMID:Angiotensin II inhibits insulin-stimulated phosphorylation of eukaryotic initiation factor 4E-binding protein-1 in proximal tubular epithelial cells. 1169 95

Dihydropyridines can inhibit gene expression in-vitro and may have a protective vascular effect independent of blood pressure reduction. We tested the hypothesis that lacidipine prevents induction of inducible NO synthase (iNOS), influences leukocyte adhesion and infiltration, inhibits nuclear factor (NF)-kappaB transcription factor activity, and ameliorates end-organ damage in a transgenic rat model of angiotensin (Ang) II--dependent organ sclerosis. We treated rats transgenic for human renin and angiotensinogen (dTGR) from week 4 to 7 with lacidipine (0.3 or 3 mg/kg by gavage). Blood pressure was measured by tail cuff. Organ damage was assessed by histology and immunohistochemistry. Adhesion molecules and cytokines were analyzed by immunohistochemistry. Transcription factors were analyzed by mobility shift assays. Untreated dTGR developed moderate hypertension, cardiac hypertrophy, and severe renal damage with albuminuria. Lacidipine decreased blood pressure slightly at the low dose and substantially at the higher dose. However, both treatments reduced albuminuria and plasma creatinine to the same degree (P<0.05). Intercellular adhesion molecule-1 (ICAM-1) was markedly reduced by lacidipine as well as renal neutrophil and monocyte infiltration. Lacidipine reduced mitogen-activated protein (MAP) kinase phosphorylation and iNOS expression in both cortex and medulla. NF-kappaB and AP-1 were activated in dTGR but reduced by lacidipine. Lacidipine ameliorates Ang II-induced end-organ damage independent of blood pressure lowering, perhaps by inhibiting the MAP kinase pathway and NF-kappaB activation.
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PMID:Lacidipine inhibits adhesion molecule and oxidase expression independent of blood pressure reduction in angiotensin-induced vascular injury. 1188 31

Angiotensin II activates three major mitogen-activated protein kinases (MAPK) in vascular smooth muscle cells. Although other angiotensin II-induced MAPKs activation require transactivation of a growth factor receptor, the detailed mechanism by which angiotensin II activates c-Jun NH(2)-terminal kinase (JNK) remains unclear. Here, an immunosuppressant, cyclosporin A but not FK506, selectively inhibited angiotensin II-induced JNK activation in vascular smooth muscle cells. However, cyclosporin A had no inhibitory effect on angiotensin II-induced protein synthesis. Thus, angiotensin II-induced JNK activation but not protein synthesis is mediated by a mechanism sensitive to cyclosporin A, which is independent from calcineurin in vascular smooth muscle cells.
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PMID:Cyclosporin A inhibits angiotensin II-induced c-Jun NH(2)-terminal kinase activation but not protein synthesis in vascular smooth muscle cells. 1204 91

We previously reported that quercetin, a bioflavonoid belonging to polyphenols, inhibited Angiotensin II (Ang II)-induced vascular smooth muscle cell (VSMC) hypertrophy through the inhibition of c-Jun N-terminal kinase (JNK) activation. However, we recently found that orally administered quercetin appeared in plasma as glucuronide-conjugated forms in rats and humans. Therefore we examined the effect of chemically synthesized quercetin glucuronide on Ang II-induced mitogen-activated protein (MAP) kinase activation and hypertrophy of cultured rat aortic smooth muscle cells (RASMC). Ang II activated extracellular signal-regulated kinase (ERK)1/2, JNK, and p38 in RASMC. Ang II-induced JNK activation was inhibited by quercetin 3-O-beta-d-glucuronide (Q3GA) whereas ERK1/2 and p38 activations were not affected. Q3GA scavenged 1,1-diphenyl-2-picrylhydrazyl radical measured by a method of electron paramagnetic resonance. Q3GA also inhibited Ang II-induced increases in activator protein-1 (AP-1) DNA binding, a downstream transcription factor of JNK. Finally, Ang II-induced [3H]leucine incorporation into RASMC was abolished by Q3GA. These findings suggest that the preventing effect of Q3GA on Ang II-induced VSMC hypertrophy is attributable in part to its inhibitory effect on JNK and the AP-1 signaling pathway. Q3GA would be an active metabolite of quercetin in plasma and may possess a preventing effect for cardiovascular diseases relevant to VSMC growth.
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PMID:Quercetin glucuronide prevents VSMC hypertrophy by angiotensin II via the inhibition of JNK and AP-1 signaling pathway. 1205 79

To understand the signaling mechanisms of atrial natriuretic peptide (ANP) receptor-A (NPRA), we studied the effect of the ANP/NPRA system on mitogen-activated protein kinases (MAPKs), with particular emphasis on the extracellular-regulated kinase (Erk2) and stress-activated protein kinase (p38MAPK) in cultured human vascular smooth muscle cells (HVSMC). Angiotensin II (ANG II) and platelet-derived growth factor (PDGF) stimulated the immunoreactive Erk2 and p38MAPK activities and their protein levels by 2-4 fold. The pretreatment of cells with ANP significantly inhibited the agonist-stimulated Erk2 and p38MAPK activities and protein expression by 65-75% in HVSMC transiently transfected with NPRA, as compared with only 18-22% inhibition in vector-transfected cells. The pretreatment of cells with KT5823, an inhibitor of cGMP-dependent protein kinase (PKG), reversed the inhibitory effects of ANP on MAPK activities and protein expression by 90-95%. PD98059, which inhibits Erk2 by directly inhibiting the MAPK-kinase (MEK), and SB202192, a selective antagonist of p38MAPK, blocked the Erk2 and p38MAPK activities, respectively. Interestingly, ANP stimulated the MAPK-phosphatase-3 (MKP-3) protein levels by more than 3-fold in HVSMC over-expressing NPRA, suggesting that ANP-dependent inhibition of MAPKs may also proceed by stimulating the phosphatase cascade. These present findings provide the evidence that ANP exerts inhibitory effects on agonist-stimulated MAPKs (Erk2 and p38MAPK) activities and protein levels in a 2-fold manner: by antagonizing the up-stream signaling pathways and by activation of MKP-3 to counter-regulate MAPKs in a cGMP and PKG-dependent manner. Our results identify a signal transduction pathway in HVSMC that could contribute to vascular remodeling and structural changes in human hypertension.
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PMID:Expression of atrial natriuretic peptide receptor-A antagonizes the mitogen-activated protein kinases (Erk2 and P38MAPK) in cultured human vascular smooth muscle cells. 1208 72

Angiotensin II (ANG II) can activate the mitogen-activated protein kinases (MAPKs) and stress-activated protein kinases in several cell types. We have previously shown that the 12-lipoxygenase (12-LO) pathway of arachidonic acid metabolism is a mediator of ANG II-induced aldosterone synthesis in adrenal glomerulosa cells. To evaluate the role of MAPK activation in ANG II and the effects of LO on aldosterone synthesis, experiments were performed using the human adrenocortical cell line H295R, which secretes aldosterone in response to ANG II. MAPK activities were determined by Western immunoblotting using specific antibodies to their activated phosphorylated forms. ANG II led to a dose-dependent increase in extracellular signal-regulated kinase (ERK1/2) activity in these cells, with a peak at 5 min and lasting up to 3 h. The effects of ANG II were blocked by the ANG-II Type 1 receptor antagonist losartan. A specific 12-LO product, 12(S)-hydroxyeicosatetraenoic acid (12-HETE), had no direct effect on ERK activity. However, both ANG II and 12-HETE led to significant dose-dependent increases in p38 MAPK activity with peak effects at 5 min. By contrast, the 15-LO product, 15-HETE, had no effect on p38 MAPK activity. Furthermore, two dissimilar 12-LO inhibitors, CDC and baicalein, blocked ANG II-induced p38 MAPK activation. ANG II significantly increased aldosterone release, and this effect was inhibited by the LO inhibitor baicalein, as well as a specific p38 MAPK inhibitor, SB202190, but not by PD098059, a specific inhibitor of the ERK activator MEK. In summary, in H295R cells, ANG II activated ERK and p38 MAPKs, ANG II-induced p38 MAPK was mediated by 12-LO activation, and ANG II-induced aldosterone synthesis was prevented by 12-LO- and p38 MAPK-specific inhibitors. These results suggest, for the first time, that activation of p38 MAPK, either directly or via LO activation, participates in aldosterone's stimulatory effects of ANG II in adrenal cells.
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PMID:Key role of P38 mitogen-activated protein kinase and the lipoxygenase pathway in angiotensin II actions in H295R adrenocortical cells. 1245 Mar 22

A major hemodynamic abnormality in hypertension is increased peripheral resistance due to changes in vascular structure and function. Structural changes include reduced lumen diameter and arterial wall thickening. Functional changes include increased vasoconstriction and/or decreased vasodilation. These processes are influenced by many humoral factors, of which angiotensin II (Ang II) seems to be critical. At the cellular level, Ang II stimulates vascular smooth muscle cell growth, increases collagen deposition, induces inflammation, increases contractility, and decreases dilation. Molecular mechanisms associated with these changes in hypertension include upregulation of many signaling pathways, including tyrosine kinases, mitogen-activated protein kinases, RhoA/Rho kinase, and increased generation of reactive oxygen species. This review focuses on the role of Ang II in vascular functional and structural changes of small arteries in hypertension. In addition, cellular processes whereby Ang II influences vessels in hypertension are discussed. Finally, novel concepts related to signaling pathways by which Ang II regulates vascular smooth muscle cells in hypertension are introduced.
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PMID:The role of angiotensin II in regulating vascular structural and functional changes in hypertension. 1264 16

In the present in vivo study, we have investigated whether inhibitors of the Na(+)/Mg(2+) exchanger quinidine and imipramine influence the development of hypertension and whether this is associated with modulation of mitogen-activated protein (MAP) kinase activation in arteries and kidneys of hypertensive rats. Sprague-Dawley rats were divided into four groups (n =6/group): control (vehicle), angiotensin II (Ang II; 150 ng/kg of body weight per min subcutaneously), quinidine [Ang II (150 ng/kg of body weight per min)+quinidine (5 mg/kg of body weight per day in food)] and imipramine groups [Ang II (150 ng/kg of body weight per min)+imipramine (5 mg/kg/day in food)]. Rats were studied for 3 weeks. Phosphorylation of vascular and renal extracellular-signal-regulated protein kinase 1/2 (ERK1/2), p38MAP kinase and c-Jun N-terminal kinase (JNK) were assessed using phospho-specific antibodies. Ang II increased systolic blood pressure from 112+/-5 mmHg to 215+/-9 mmHg ( P <0.01). Development of hypertension was attenuated in Ang II-infused rats treated with quinidine (173+/-6 mmHg) and imipramine (152+/-6 mmHg) (P <0.01). Phosphorylation of ERK1/2, p38MAP kinase and JNK, which were increased 2-3-fold in arteries of the Ang II group, were reduced by quinidine and imipramine (P <0.05). Activation of renal MAP kinases was also increased in the Ang II group (P <0.05). Quinidine and imipramine reduced the phosphorylation of renal ERK1/2, but did not modify renal p38MAP kinase or JNK. Our data demonstrate that Ang II induces severe hypertension in Sprague-Dawley rats and this is associated with increased phosphorylation of vascular and renal MAP kinases. Quinidine and imipramine attenuated the development of hypertension and normalized MAP kinase activity. The findings from this study suggest a possible role for the Na(+)/Mg(2+) exchanger in vascular signalling events associated with blood pressure elevation in Ang II-dependent hypertension.
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PMID:Up-regulation of vascular and renal mitogen-activated protein kinases in hypertensive rats is normalized by inhibitors of the Na+/Mg2+ exchanger. 1272 44

In addition to their physiological roles in the cardiovascular system (CVS), G-protein-coupled receptor (GPCR) agonists such as noradrenaline, endothelin-1 and angiotensin II (Ang II) are known to be involved in the development of cardiac hypertrophy. Recent studies using targeted overexpression of the angiotensin AT(1) receptor in cardiomyocytes suggest that Ang II can directly promote the growth of cardiomyocytes via transactivation of the epidermal growth factor (EGF) receptor and subsequent activation of mitogen-activated protein kinases (MAPKs). This process is mediated by the production of heparin-binding EGF (HB-EGF) by metalloproteases. Blockade of the generation of HB-EGF by metalloprotease inhibitors, or abrogation of EGF receptor kinase activity by selective pharmacological inhibitors or antisense oligonucleotides, protects against Ang II-mediated cardiac hypertrophy. These approaches offer a potential therapeutic strategy to prevent cardiac remodeling and hypertrophy, and possibly prevent progression to heart failure.
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PMID:A central role of EGF receptor transactivation in angiotensin II -induced cardiac hypertrophy. 1276 23

Angiotensin II (AT II) is thought to be associated with the development of renal interstitial fibrosis. However, the molecular mechanisms of the interstitial fibrosis have not been extensively studied. We have examined the role of mitogen-activated protein kinases (MAPKs) on fibronectin (FN) accumulation in cultured normal rat kidney interstitial fibroblasts (NRK 49F cell line). AT II caused dose-dependent increases in FN accumulation and FN mRNA in these cells. AT II also activated the extracellular signal-regulated kinase (ERK) and p38 MAPK in the presence of AT II. These increases in FN accumulation and activation of MAPKs were inhibited with AT I receptor antagonist (ARB; CV-11974) in renal interstitial fibroblasts. The inhibitors against ERK (PD98059) and p38 MAPK (SB203580) significantly inhibited AT II-induced increases in FN mRNA. These findings suggest that the MAPKs play an important role in AT II-mediated renal interstitial fibrosis and that ARB may be useful for preventing renal interstitial fibrosis.
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PMID:Possible involvement of mitogen-activated protein kinase in the angiotensin II-induced fibronectin synthesis in renal interstitial fibroblasts. 1280 13


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