81 research outputs found
Resveratrol Inhibits Inflammatory Responses via the Mammalian Target of Rapamycin Signaling Pathway in Cultured LPS-Stimulated Microglial Cells
Resveratrol have been known to possess many pharmacological properties including antioxidant, cardioprotective and anticancer effects. Although current studies indicate that resveratrol produces neuroprotection against neurological disorders, the precise mechanisms for its beneficial effects are still not fully understood. We investigate the effect of anti-inflammatory and mechamisms of resveratrol by using lipopolysaccharide (LPS)-stimulated murine microglial BV-2 cells.BV-2 cells were treated with resveratrol (25, 50, and 100 µM) and/or LPS (1 µg/ml). Nitric oxide (NO) and prostaglandin E2 (PGE2) were measured by Griess reagent and ELISA. The mRNA and protein levels of proinflammatory proteins and cytokines were analysed by RT-PCR and double immunofluorescence labeling, respectively. Phosphorylation levels of PTEN (phosphatase and tensin homolog deleted on chromosome 10), Akt, mammalian target of rapamycin (mTOR), mitogen-activated protein kinases (MAPKs) cascades, inhibitor κB-α (IκB-α) and cyclic AMP-responsive element-binding protein (CREB) were measured by western blot. Resveratrol significantly attenuated the LPS-induced expression of NO, PGE2, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and nuclear factor-κB (NF-κB) in BV-2 cells. Resveratrol increased PTEN, Akt and mTOR phosphorylation in a dose-dependent manner or a time-dependent manner. Rapamycin (10 nM), a specific mTOR inhibitor, blocked the effects of resveratrol on LPS-induced microglial activation. In addition, mTOR inhibition partially abolished the inhibitory effect of resveratrol on the phosphorylation of IκB-α, CREB, extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal protein kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK).This study indicates that resveratrol inhibited LPS-induced proinflammatory enzymes and proinflammatory cytokines via down-regulation phosphorylation of NF-κB, CREB and MAPKs family in a mTOR-dependent manner. These findings reveal, in part, the molecular basis underlying the anti-inflammatory properties of resveratrol
Resveratrol Targeting of Carcinogen-Induced Brain Endothelial Cell Inflammation Biomarkers MMP-9 and COX-2 is Sirt1-Independent
The occurrence of a functional relationship between the release of metalloproteinases (MMPs) and the expression of cyclooxygenase (COX)-2, two inducible pro-inflammatory biomarkers with important pro-angiogenic effects, has recently been inferred. While brain endothelial cells play an essential role as structural and functional components of the blood-brain barrier (BBB), increased BBB breakdown is thought to be linked to neuroinflammation. Chemopreventive mechanisms targeting both MMPs and COX-2 however remain poorly investigated. In this study, we evaluated the pharmacological targeting of Sirt1 by the diet-derived and antiinflammatory polyphenol resveratrol. Total RNA, cell lysates, and conditioned culture media from human brain microvascular endothelial cells (HBMEC) were analyzed using qRT-PCR, immunoblotting, and zymography respectively. Tissue scan microarray analysis of grade I–IV brain tumours cDNA revealed increased gene expression of Sirt-1 from grade I–III but surprisingly not in grade IV brain tumours. HBMEC were treated with a combination of resveratrol and phorbol 12-myristate 13-acetate (PMA), a carcinogen known to increase MMP-9 and COX-2 through NF-κB. We found that resveratrol efficiently reversed the PMA-induced MMP-9 secretion and COX-2 expression. Gene silencing of Sirt1, a critical modulator of angiogenesis and putative target of resveratrol, did not lead to significant reversal of MMP-9 and COX-2 inhibition. Decreased resveratrol inhibitory potential of carcinogen-induced IκB phosphorylation in siSirt1-transfected HBMEC was however observed. Our results suggest that resveratrol may prevent BBB disruption during neuroinflammation by inhibiting MMP-9 and COX-2 and act as a pharmacological NF-κB signal transduction inhibitor independent of Sirt1
Idebenone and Resveratrol Extend Lifespan and Improve Motor Function of HtrA2 Knockout Mice
Heterozygous loss-of-function mutation of the human gene for the mitochondrial protease HtrA2 has been associated with increased risk to develop mitochondrial dysfunction, a process known to contribute to neurodegenerative disorders such as Huntington's disease (HD) and Parkinson's disease (PD). Knockout of HtrA2 in mice also leads to mitochondrial dysfunction and to phenotypes that resemble those found in neurodegenerative disorders and, ultimately, lead to death of animals around postnatal day 30. Here, we show that Idebenone, a synthetic antioxidant of the coenzyme Q family, and Resveratrol, a bioactive compound extracted from grapes, are both able to ameliorate this phenotype. Feeding HtrA2 knockout mice with either compound extends lifespan and delays worsening of the motor phenotype. Experiments conducted in cell culture and on brain tissue of mice revealed that each compound has a different mechanism of action. While Idebenone acts by downregulating the integrated stress response, Resveratrol acts by attenuating apoptosis at the level of Bax. These activities can account for the delay in neuronal degeneration in the striata of these mice and illustrate the potential of these compounds as effective therapeutic approaches against neurodegenerative disorders such as HD or PD
Resveratrol Inhibits Protein Translation in Hepatic Cells
Resveratrol is a plant-derived polyphenol that extends lifespan and healthspan in model organism. Despite extensive investigation, the biological processes mediating resveratrol's effects have yet to be elucidated. Because repression of translation shares many of resveratrol's beneficial effects, we hypothesized that resveratrol was a modulator of protein synthesis. We studied the effect of the drug on the H4-II-E rat hepatoma cell line. Initial studies showed that resveratrol inhibited global protein synthesis. Given the role of the mammalian Target of Rapamycin (mTOR) in regulating protein synthesis, we examined the effect of resveratrol on mTOR signaling. Resveratrol inhibited mTOR self-phosphorylation and the phosphorylation of mTOR targets S6K1 and eIF4E-BP1. It attenuated the formation of the translation initiation complex eIF4F and increased the phosphorylation of eIF2α. The latter event, also a mechanism for translation inhibition, was not recapitulated by mTOR inhibitors. The effects on mTOR signaling were independent of effects on AMP-activated kinase or AKT. We conclude that resveratrol is an inhibitor of global protein synthesis, and that this effect is mediated through modulation of mTOR-dependent and independent signaling
Opposing Effects of Sirtuins on Neuronal Survival: SIRT1-Mediated Neuroprotection Is Independent of Its Deacetylase Activity
Background: Growing evidence suggests that sirtuins, a family of seven distinct NAD-dependent enzymes, are involved in the regulation of neuronal survival. Indeed, SIRT1 has been reported to protect against neuronal death, while SIRT2 promotes neurodegeneration. The effect of SIRTs 3–7 on the regulation of neuronal survival, if any, has yet to be reported. Methodology and Principal Findings: We examined the effect of expressing each of the seven SIRT proteins in healthy cerebellar granule neurons (CGNs) or in neurons induced to die by low potassium (LK) treatment. We report that SIRT1 protects neurons from LK-induced apoptosis, while SIRT2, SIRT3 and SIRT6 induce apoptosis in otherwise healthy neurons. SIRT5 is generally localized to both the nucleus and cytoplasm of CGNs and exerts a protective effect. In a subset of neurons, however, SIRT5 localizes to the mitochondria and in this case it promotes neuronal death. Interestingly, the protective effect of SIRT1 in neurons is not reduced by treatments with nicotinamide or sirtinol, two pharmacological inhibitors of SIRT1. Neuroprotection was also observed with two separate mutant forms of SIRT1, H363Y and H355A, both of which lack deacetylase activity. Furthermore, LK-induced neuronal death was not prevented by resveratrol, a pharmacological activator of SIRT1, at concentrations at which it activates SIRT1. We extended our analysis to HT-22 neuroblastoma cells which can be induced to die by homocysteic acid treatment. While the effects of most of the SIRT proteins were similar to that observed in CGNs, SIRT6 was modestly protective against homocysteic acid toxicity in HT-22 cells. SIRT5 was generally localized in th
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Genetic variation in drought hardiness of coastal Douglas-fir seedlings from British Columbia
Abstract: Genetic variation in drought hardiness traits and their genetic correlations with growth potential and17re1c6overy
traits were investigated in 39 full-sib families of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.)
Franco) from southwestern British Columbia. Seedlings of these families were grown in raised nursery beds and subjected
to three moisture regimes each in the second (well-watered or control, mild, and moderate drought) and third
(control, severe drought, and recovery from second-year moderate drought) seasons. Traits assessed included drought
hardiness (foliage damage, cavitation of xylem tracheids, xylem hydraulic conductivity, and height and diameter growth
increment) in the drought treatments, growth potential (total height and diameter) in the control treatment, and height
and diameter growth increments in the recovery treatment. Xylem cavitation in the growth ring produced in a particular
year was nearly three times greater under the moderate drought and four times greater under the severe drought than in
the control treatment. Xylem hydraulic conductivity of seedlings in the severe drought treatment was 40% lower than
conductivity of seedlings under the control treatment. Mean foliage damage in seedlings subjected to severe drought
(third season) was much greater (33%) than in seedlings subjected to mild or moderate drought (second season). Families
differed significantly in most drought hardiness traits, with individual tree heritabilities averaging 0.19. Thus,
much potential exists for identifying drought-hardy families at the seedling stage and using this information for deployment
or breeding purposes. In addition, most hardiness traits were strongly intercorrelated (genetic correlations often
exceeded |0.80|) indicating that these traits are controlled largely by the same set of genes and that selection for hardiness
based on one trait will increase hardiness as reflected in the other traits as well. Genetic correlations were only
moderate (0.49) between hardiness traits measured in different years, perhaps due to the large difference in severity of
the drought applied in the two seasons. Although injury to seedlings, as reflected in foliage damage and xylem cavitation,
was relatively low under the moderate drought of the second season, it did result in reduced growth increment the
following (recovery) year. Growth potential under favorable moisture regimes was nearly uncorrelated with drought hardiness,
suggesting that drought hardiness could be improved in this southwestern British Columbia breeding population
without negatively impacting growth potential in favorable moisture conditions
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Genetics of cold hardiness in a cloned full-sib family of coastal Douglas-fir
Variation in cold-hardiness traits, and their extent of genetic control and interrelationships, were investigated
among individuals (clones) within a single large full-sib family of coastal Douglas-fir (Pseudotsuga menziesii var.
menziesii (Mirb.) Franco) from Oregon. Cold injury to needle, stem, and bud tissues was evaluated in fall 1996 and
spring 1997 following artificial freeze testing of detached shoots collected from 4-year-old ramets (rooted cuttings).
Variation among clones in cold-injury scores was significant (p < 0.01) for all shoot tissues in both fall and spring and
averaged about three times the magnitude previously observed among open-pollinated families of this species. Thus,
improving cold hardiness by within-family selection appears to hold much promise. Striking similarities in relative
magnitudes of heritability estimates and genetic correlations in the full-sib family, compared with breeding populations,
support the following hypotheses about the quantitative genetics of cold hardiness in this species: (i) heritability of
cold hardiness (both broad-and-narrow-sense) is stronger in the spring than in the fall; (ii) cold hardiness of different
shoot tissues in the same season is controlled by many of the same genes; and (iii) genetic control of fall cold hardiness
is largely independent of cold hardiness in the spring.Keywords: Douglas-fir, genetic
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