SUMMARY A small molecule that safely mimics the ability of dietary restriction (DR) to delay age-related diseases in laboratory animals is greatly sought after. We and others have shown that resveratrol mimics effects of DR in lower organisms. In mice, we find that resveratrol induces gene expression patterns in multiple tissues that parallel those induced by DR and every-other-day feeding. Moreover, resveratrol-fed elderly mice show a marked reduction in signs of aging including reduced albuminuria, decreased inflammation and apoptosis in the vascular endothelium, increased aortic elasticity, greater motor coordination, reduced cataract formation, and preserved bone mineral density. However, mice fed a standard diet did not live longer when treated with resveratrol beginning at 12 months of age. Our findings indicate that resveratrol treatment has a range of beneficial effects in mice but does not increase the longevity of ad libitum-fed animals when started mid-life.

A major cause of cell death caused by genotoxic stress is thought to be due to the depletion of NAD(+) from the nucleus and the cytoplasm. Here we show that NAD(+) levels in mitochondria remain at physiological levels following genotoxic stress and can maintain cell viability even when nuclear and cytoplasmic pools of NAD(+) are depleted. Rodents fasted for 48 hr show increased levels of the NAD(+) biosynthetic enzyme Nampt and a concomitant increase in mitochondrial NAD(+). Increased Nampt provides protection against cell death and requires an intact mitochondrial NAD(+) salvage pathway as well as the mitochondrial NAD(+)-dependent deacetylases SIRT3 and SIRT4. We discuss the relevance of these findings to understanding how nutrition modulates physiology and to the evolution of apoptosis.

Estrogen receptors (ERs) are believed to be ligand-activated transcription factors belonging to the nuclear receptor superfamily, which on ligand binding translocate into the nucleus and activate gene transcription. To date, two ERs have been identified: ER␣ and ER␤. ER␣ plays major role in the estrogen-mediated genomic actions in both reproductive and nonreproductive tissue, whereas the function of ER␤ is still unclear. In this study, we used immunocytochemistry, immunoblotting, and proteomics to demonstrate that ER␤ localizes to the mitochondria. In immunocytochemistry studies, ER␤ was detected with two ER␤ antibodies and found to colocalize almost exclusively with a mitochondrial marker in rat primary neuron, primary cardiomyocyte, and a murine hippocampal cell line. The colocalization of ER␤ and mitochondrial markers was identified by both fluorescence and confocal microscopy. No translocation of ER␤ into the nucleus on 17␤-estradiol treatment was seen by using immunocytochemistry. Immunoblotting of purified human heart mitochondria showed an intense signal of ER␤, whereas no signals for nuclear and other organelle markers were found. Finally, purified human heart mitochondrial proteins were separated by SDS͞PAGE. The 50,000 -65,000 Mr band was digested with trypsin and subjected to matrix-assisted laser desorption͞ionization mass spectrometric analysis, which revealed seven tryptic fragments that matched with those of ER␤. In summary, this study demonstrated that ER␤ is localized to mitochondria, suggesting a role for mitochondrial ER␤ in estrogen effects on this important organelle.nuclear receptor ͉ mitochondria E strogens play an important role in development, growth, and differentiation of both female and male secondary sex characteristics. Estrogen receptors (ERs) were the first identified nuclear receptor family member (1). The first ER, now called ER␣, was cloned in 1986 (2, 3). A second ER␤, was identified and cloned a decade later (4, 5). Like other members of the nuclear receptor superfamily, both ERs have a modular structure consisting of distinct functional domains (1). The DNA-binding domain (DBD) enables the receptor to bind its cognate target site consisting of an inverted repeat of two half-sites with the consensus motif AG-GTCA spaced by 3 bp, referred to as an estrogen response element (ERE). The ligand-binding domain enables estrogen binding to the receptors. ERs are highly conserved between ER␣ and ER␤, with Ͼ95% homology for the DBD and Ϸ50% homology for the ligand-binding domain. Less homology is observed for the transactivational domain between ER␣ and ER␤ (5, 6).Genomic actions of ER␣ are well described (7). On binding to ER␣, estrogens induce a conformational change in the ER␣ proteins, which is accompanied by the dissociation of the accessory protein, heat shock protein 90, thereby exposing the DBD. In the nucleus, the receptor-ligand complex binds to DNA and modulates gene transcription. This transcriptional͞translational activation is comparatively slow and sensitive to cyclohexi...

Substantial evidence now exists that intrinsic free-radical scavenging contributes to the receptor-independent neuroprotective effects of estrogens. This activity is inherently associated with the presence of a phenolic A-ring in the steroid. We report a previously unrecognized antioxidant cycle that maintains the ''chemical shield'' raised by estrogens against the most harmful reactive oxygen species, the hydroxyl radical ( • OH) produced by the Fenton reaction. In this cycle, the capture of • OH was shown to produce a nonphenolic quinol with no affinity to the estrogen receptors. This quinol is then rapidly converted back to the parent estrogen via an enzyme-catalyzed reduction by using NAD(P)H as a coenzyme (reductant) and, unlike redox cycling of catechol estrogens, without the production of reactive oxygen species. Due to this process, protection of neuronal cells against oxidative stress is also possible by quinols that essentially act as prodrugs for the active hormone. We have shown that the quinol obtained from a 17␤-estradiol derivative was, indeed, able to attenuate glutamate-induced oxidative stress in cultured hippocampus-derived HT-22 cells. Estrone quinol was also equipotent with its parent estrogen in reducing lesion volume in ovariectomized rats after transient middle carotid artery occlusion followed by a 24-h reperfusion. These findings may establish the foundation for a rational design of neuroprotective antioxidants focusing on steroidal quinols as unique molecular leads.hydroxyl radical ͉ ischemia ͉ prodrug