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The role of prostaglandins E1 and ..

To investigate whether resveratrol affects thePGE-stimulated OPG synthesis through the activation ofp44/p42 MAP kinase, p38 MAP kinase or SAPK/JNK in osteoblast-likeMC3T3-E1 cells, we examined the effects of resveratrol on thePGE-induced phosphorylation of p44/p42 MAP kinase, p38MAP kinase or SAPK/JNK. Resveratrol suppressed thePGE-induced phosphorylation of p44/p42 MAP kinase(), p38 MAP kinase() and SAPK/JNK () in a dose-dependent manner at thedose range between 10 and 50 μM. We further examined the effects ofSRT1720 on the PGE-induced phosphorylation of p44/p42MAP kinase, p38 MAP kinase or SAPK/JNK. However, SRT1720 hardlyaffected the PGE-induced phosphorylation of p44/p42 MAPkinase, p38 MAP kinase or SAPK/JNK ().

This is a detailed report of efforts to synthesize compounds related to PGE1 (prostaglandin E1)

It is firmly established that the major MAP kinasesuperfamily, including p44/p42 MAP kinase, p38 MAP kinase andSAPK/JNK, is a central element used by mammalian cells to transducevarious messages of extracellular stimuli (). As regards PGEintracellular signaling in osteoblasts, we have previously reportedthat p44/p42 MAP kinase and p38 MAP kinase are involved in theHSP27 induction by PGE in osteoblast-like MC3T3-E1cells (). In order to clarifywhether p44/p42 MAP kinase, p38 MAP kinase or SAPK/JNK are involvedin the PGE-stimulated OPG synthesis in osteoblast-likeMC3T3-E1 cells, we examined the effects of PD98059, a specificinhibitor of the upstream kinase activating p44/p42 MAP kinase(), SB203580, a specificinhibitor of p38 MAP kinase ()or SP600125, a specific inhibitor of SAPK/JNK (), on the release of OPG stimulated byPGE. PD98059, SB203580 and SP600125, which alone hadlittle effect on the release of OPG, markedly reduced thePGE-stimulated release of OPG in these cells ().

Total synthesis of prostaglandins

New chemical strategies have led to the synthesis of enantiomerically pure B1-,F1- and E1-phytoprostane ().

Evidence is accumulating that the beneficial effectsof resveratrol are mediated through SIRT1 activation (). On the other hand, we demonstratedthat SRT1720, a potent activator of SIRT1 (), exerted minimal effects on thePGE-stimulated release of OPG and on thephosphorylation of the three MAP kinases induced by PGEin osteoblast-like MC3T3-E1 cells. Therefore, it seems unlikelythat the inhibitory effects of resveratrol on thePGE-induced events shown in our study areSIRT1-dependent in these cells. In a previous study of ours(), we demonstrated thatresveratrol significantly suppressed the BMP-4-induced VEGFsynthesis, and that the effects were mediated at least in part bythe activation of SIRT1 in MC3T3-E1 cells. Based on our findings,it is possible that the intracellular signaling mechanismsunderlying the effects of resveratrol in osteoblasts arecharacterized according to each agonist or product. It has beenreported that resveratrol affects the cellular function ofadipocytes and regulates the number of fat cells in aSIRT1-independent manner (,). Since both osteoblasts andadipocytes originate from undifferentiated mesenchymal stem cells,the SIRT-independent effects of resveratrol observed in osteoblastsmay be due to these same stem cells.

The three major MAP kinases, p44/p42 MAP kinase, p38MAP kinase and SAPK/JNK are recognized as central elements used bymammalian cells to transduce diverse messages () and play central roles in a varietyof cellular functions, including proliferation, differentiation andsurvival (). As regards theintracellular signaling of PGE in osteoblasts, we havepreviously demonstrated that PGE induces the activationof p44/p42 MAP kinase and p38 MAP kinase in osteoblast-likeMC3T3-E1 cells, and that PGE stimulates the inductionof HSP27 through the PKC-dependent activation of both p44/p42 MAPkinase and p38 MAP kinase in MC3T3-E1 cells (). In the present study, we found thatPGE stimulated the phosphorylation of SAPK/JNK in theMC3T3-E1 cells in a time-dependent manner and the most prominenteffects of PGE were observed at 20 min followingstimulation (data not shown). It is generally established that MAPkinases are activated by the phosphorylation of threonine andtyrosine residues by dual-specificity MAP kinase kinase (). Therefore, our findings suggestthat PGE stimulates the activation of SAPK/JNK inaddition to that of p44/p42 MAP kinase and p38 MAP kinase inosteoblast-like MC3T3-E1 cells. Furthermore, we demonstrated thatPD98059, a specific inhibitor of the upstream kinase activatingp44/p42 MAP kinase (),SB203580, a specific inhibitor of p38 MAP kinase () and SP600125, a specific inhibitorof SAPK/JNK () markedlyreduced the PGE-stimulated release of OPG, suggestingthat three major MAP kinases, namely the p44/p42 MAP kinase, p38MAP kinase and SAPK/JNK function as positive regulators in thePGE-stimulated OPG synthesis in these cells. Inaddition, we demonstrated that resveratrol markedly suppressed thephosphorylation of p44/p42 MAP kinase, p38 MAP kinase and SAPK/JNKinduced by PGE in the MC3T3-E1 cells. Taking ourfindings into account, it is likely that resveratrol inhibits thePGE-induced OPG synthesis in osteoblast-like cells, andthat the suppressive effects of resveratrol are exerted at a pointupstream of three MAP kinases.

Download Total synthesis of prostaglandins. VII. …

Accumulating data suggest that the interaction of various enzymes in the Prostaglandin E2 synthetic pathway is complex and tightly regulated.

Effects of SRT1720 on theprostaglandin E2 (PGE2)-stimulated release ofosteoprotegerin (OPG) in MC3T3-E1 cells. The cultured cells werepre-treated with various concentrations of SRT1720 for 60 min andthen stimulated with 10 μM of PGE2 (●) or the vehicle(○) for 48 h. OPG concentrations in the culture medium weredetermined by ELISA. Each value represents the mean ± SEM oftriplicate determinations from 3 independent cell preparations.

Effects of resveratrol on theprostaglandin E2 (PGE2)-induced mRNAexpression of osteoprotegerin (OPG) in MC3T3-E1 cells. The culturedcells were pre-treated with 50 μM of resveratrol or the vehicle for60 min and then stimulated with 10 μM of PGE2 or thevehicle for 3 h. The respective total RNA was then isolated andquantified by real-time RT-PCR. Each value represents the mean ±SEM of triplicate determinations from 3 independent cellpreparations. *P

Efficacy and safety of prostaglandin E1 plus lipoic acid combination therapy versus monotherapy for patients with diabetic peripheral neuropathy.
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Corey et al., Total Synthesis of Prostaglandins F1x, E1, F2x, and E2

Effects of resveratrol on theprostaglandin E2 (PGE2)-inducedphosphorylation of p44/p42 mitogen-activated protein (MAP) kinasein MC3T3-E1 cells. The cultured cells were pre-treated with variousconcentrations of resveratrol for 60 min and then stimulated with10 μM of PGE2 or the vehicle for 10 min. The cellextracts were then subjected to SDS-PAGE with subsequent westernblot analysis with antibodies against phospho-specific p44/p42 MAPkinase or p44/p42 MAP kinase. The histogram shows the quantitativerepresentation of the levels of PGE2-inducedphosphorylation obtained from a laser densitometric analysis of 3independent experiments. Each value represents the mean ± SEM oftriplicate determinations. *P

The effects of prostaglandins E1, E2 and F2alpha on …

Effects of resveratrol on theprostaglandin E2 (PGE2)-inducedphosphorylation of p38 mitogen-activated protein (MAP) kinase inMC3T3-E1 cells. The cultured cells were pre-treated with variousconcentrations of resveratrol for 60 min and then stimulated with10 μM of PGE2 or the vehicle for 3 min. The cellextracts were then subjected to SDS-PAGE with subsequent westernblot analysis with antibodies against phospho-specific p38 MAPkinase or p38 MAP kinase. The histogram shows the quantitativerepresentation of the levels of PGE2-inducedphosphorylation obtained from a laser densitometric analysis of 3independent experiments. Each value represents the mean ± SEM oftriplicate determinations. *P

The effects of prostaglandins E1, ..

Effects of resveratrol on theprostaglandin E2 (PGE2)-stimulated release ofosteoprotegerin (OPG) in MC3T3-E1 cells. The cultured cells werepre-treated with various concentrations of resveratrol for 60 minand then stimulated with 10 μM of PGE2 (●) or thevehicle (○) for 48 h. OPG concentrations in the culture medium weredetermined by ELISA. Each value represents the mean ± SEM oftriplicate determinations from 3 independent cell preparations.*P

so preventing the synthesis of prostaglandins …

1 In anesthetized mice prostaglandins E1 and E2 reduced the bradycardia caused by electrical stimulation of the sectioned peripheral vagus nerve; prostaglandin F2alpha produced only a slight inhibition of the vagal response. 2 None of the prostaglandins studied affected acetylcholine-induced bradycardia. 3 Prostaglandins modify parasympathetic nerve activity in vivo presumably by a pre-synaptic action.

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