Excessive reactive oxygen species (ROS) induce apoptosis and are associated with various diseases and with aging. SIRT1 (sirtuin-1), an NAD+-dependent protein deacetylase, decreases ROS levels and participates in cell survival under oxidative stress conditions. SIRT1 modulates the transcription factors p53, a tumor suppressor and inducer of apoptosis, and the forkhead O (FOXO) family, both of which play roles for cell survival and cell death. In this study, we aimed to know which is working greatly among p53 and FOXOs transcription factors in SIRT1’s cell protective functions under oxidative stress conditions. The antimycin A-induced increase in ROS levels and apoptosis was enhanced by SIRT1 inhibitors nicotinamide and splitomicin, whereas it was suppressed by a SIRT1 activator, resveratrol, and a SIRT1 cofactor, NAD+. SIRT1-siRNA abolished the effects of splitomicin and resveratrol. p53-knockdown experiment in C2C12 cells and experiment using p53-deficient HCT116 cells showed that splitomicin and resveratrol modulated apoptosis by p53-dependent and p53-independent pathways. In p53-independent cell protective pathway, we found that FOXO1, FOXO3a, and FOXO4 were involved in SOD2’s upregulation by resveratrol. The knockdown of these three FOXOs by siRNAs completely abolished the SOD2 induction, ROS reduction, and anti-apoptotic function of resveratrol. Our results indicate that FOXO1, FOXO3a and FOXO4, are indispensable for SIRT1-dependent cell survival against oxidative stress, although deacetylation of p53 has also some role for cell protective function of SIRT1.

Muscular dystrophies are inherited myogenic disorders accompanied by progressive skeletal muscle weakness and degeneration. We previously showed that resveratrol (3,5,4Ј-trihydroxy-trans-stilbene), an antioxidant and activator of the NAD ϩ -dependent protein deacetylase SIRT1, delays the progression of heart failure and prolongs the lifespan of ␦-sarcoglycan-deficient hamsters. Because a defect of dystroglycan complex causes muscular dystrophies, and ␦-sarcoglycan is a component of this complex, we hypothesized that resveratrol might be a new therapeutic tool for muscular dystrophies. Here, we examined resveratrol's effect in mdx mice, an animal model of Duchenne muscular dystrophy. mdx mice that received resveratrol in the diet for 32 weeks (4 g/kg diet) showed significantly less muscle mass loss and nonmuscle interstitial tissue in the biceps femoris compared with mdx mice fed a control diet. In the muscles of these mice, resveratrol significantly decreased oxidative damage shown by the immunostaining of nitrotyrosine and 8-hydroxy-2Ј-deoxyguanosine and suppressed the up-regulation of NADPH oxidase subunits Nox4, Duox1, and p47 phox . Resveratrol also reduced the number of ␣-smooth muscle actin (␣-SMA) ϩ myofibroblast cells and endomysial fibrosis in the biceps femoris, although the infiltration of CD45ϩ inflammatory cells and increase in transforming growth factor-␤1 (TGF-␤1) were still observed. In C2C12 myoblast cells, resveratrol pretreatment suppressed the TGF-␤1-induced increase in reactive oxygen species, fibronectin production, and expression of ␣-SMA, and SIRT1 knockdown blocked these inhibitory effects. SIRT1 small interfering RNA also increased the expression of Nox4, p47 phox , and ␣-SMA in C2C12 cells. Taken together, these findings indicate that SIRT1 activation may be a useful strategy for treating muscular dystrophies.

Background: Dystrophin deficiency leads to life-threatening cardiomyopathy, whereas cardiac p300 promotes cardiac hypertrophy/failure. Results: The SIRT1 activator resveratrol inhibited p300 protein up-regulation and attenuated cardiomyopathy in dystrophindeficient mice, and SIRT1-induced p300 down-regulation was mediated via its deacetylation and ubiquitination. Conclusion: SIRT1 activation ameliorates dystrophic cardiomyopathy by targeting p300. Significance: Negative regulation of p300 is a novel cardioprotective mechanism of SIRT1.

Mitochondrial autophagy eliminates damaged mitochondria and decreases reactive oxygen species (ROS). The autophagy inhibitor chloroquine (CQ) potentiates temozolomide (TMZ) cytotoxicity in glioma cells, but it is not known whether CQ does this by inhibiting mitochondrial autophagy. The effects of CQ and TMZ on MitoSOX Red fluorescence, a mitochondrial ROS indicator, and cell death were examined in rat C6 glioma cells. Mitochondrial autophagy was monitored by the colocalization of MitoTracker Red fluorescence and EGFP-LC3 dots. Mitochondrial content was measured by MitoTracker Green fluorescence and immunoblotting for a mitochondrial protein. Finally, CQ's effects on tumor cells derived from a glioblastoma patient and human U87-MG glioblastoma cells were assessed. TMZ (100-1,000 μM) alone did not affect mitochondrial ROS or cell death in C6 cells, but when administered with CQ (10 μM), it increased mitochondrial ROS and cell death. Antioxidants significantly suppressed the CQ-augmented cell death in TMZ-treated cells, indicating that mitochondrial ROS were involved in this cell death. TMZ treatment reduced MitoTracker Green fluorescence and mitochondrial protein levels, and these effects were inhibited by CQ. TMZ also increased the colocalization of EGFP-LC3 dots with mitochondria, and CQ enhanced this effect. CQ potentiated TMZ-induced cytotoxicity in patient-derived glioblastoma cells as well as human U87-MG glioblastoma cells. These results suggest that CQ increases cellular ROS and augments TMZ cytotoxicity in glioma cells by inhibiting mitochondrial autophagy.

Coffee and polyphenol consumption was associated with low facial pigmented spots in Japanese middle-aged females. We speculated that coffee helps protect human skin from photoaging, and polyphenols, including chlorogenic acids, may contribute to the decreased hyperpigmentation of pigmented spots.

Resveratrol (trans-3,5,49-trihydroxystilbene; RSV), a natural polyphenol, exerts a beneficial effect on health and diseases. RSV targets and activates the NAD 1 -dependent protein deacetylase SIRT1; in turn, SIRT1 induces an intracellular antioxidative mechanism by inducing mitochondrial superoxide dismutase (SOD2). Most RSV found in plants is glycosylated, and the effect of these glycosylated forms on SIRT1 has not been studied. In this study, we compared the effects of RSV and two glycosyl RSVs, resveratrol-3-O-b-D-glucoside (3G-RSV; polydatin/piceid) and resveratrol-49-O-b-D-glucoside (49G-RSV), at the cellular level. In oxygen radical absorbance capacity and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays, the antioxidant activity of 3G-RSV was comparable to that of RSV, whereas the radical-scavenging efficiency of 49G-RSV was less than 50% of that of RSV. However, 49G-RSV, but not 3G-RSV, induced SIRT1-dependent histone H3 deacetylation and SOD2 expression in mouse C2C12 skeletal myoblasts; as with RSV, SIRT1 knockdown blunted these effects. RSV and 49G-RSV, but not 3G-RSV, mitigated oxidative stress-induced cell death in C2C12 cells and primary neonatal rat cardiomyocytes. RSV and 49G-RSV inhibited C2C12 cell proliferation, but 3G-RSV did not. RSV was found in both the intracellular and extracellular fractions of C2C12 cells that had been incubated with 49G-RSV, indicating that 49G-RSV was extracellularly deglycosylated to RSV, which was then taken up by the cells. C2C12 cells did not deglycosylate 3G-RSV. Our results point to 49G-RSV as a useful RSV prodrug with high water solubility. These data also show that the in vitro antioxidative activity of these molecules did not correlate with their ability to protect cells from oxidative stress-induced apoptosis.

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