of the Research Plan Despite significant research effort to understand the aging process, we are still not able to confidently answer fundamental questions: Why do we age and can we delay it in humans? Recent studies suggest that various age-related pathophysiological conditions may have common underpinnings, the so-called hallmarks of aging that include mitochondrial defects, cellular senescence and inflammation. Our research group has worked for more than a decade on NAD+-dependent lysine deacetylases known as the Sirtuins (SIRT1-7). Thanks to this grant, we discovered a new cause of aging that explains why mitochondrial function declines with age, a process we call ?Genome Asynchrony?. Genome asynchrony manifests in heart and muscle tissue (and possibly other tissues) as a breakdown in nuclear-mitochondrial communication due to a decline the NAD+ levels and loss of SIRT1 activity. The result is the stabilization of the hypoxia factor HIF-1? in the absence of hypoxia (a phenomenon we call ?pseudohypoxia?) and a potent inhibitory effect on nuclear- mitochondrial communication. Importantly, by feeding old mice the NAD+ precursor, nicotinamide mononucleotide (NMN), for one week, thus restoring NAD+ to youthful levels, the mitochondrial defects of old muscle can be rapidly reversed, demonstrating that NAD+ is a key regulator of aspects of aging in mice and that aspects of aging are reversible. During the study we discovered that the NMN treatment was able to rapidly reverse key markers of aging in the muscle, suggesting declining NAD+ levels may underlie inflammation during aging. We find that NAD+ levels and HIF-1? specifically control the secretion of IL-18 and IL-1? by regulating the activity of the inflammasome, a key regulator of healthspan in mammals. In the next phase of the grant, we will determine the NAD+-dependent mechanisms that regulate inflammation along with its role in the secretory phenotype of senescent cells (SASP) and test interventions to counteract these pathways.
Aim 1 is to use primary macrophages from genetically modified mice (GEMMs), along with novel epigenetic manipulation technologies and clinic-ready small molecules to test our hypotheses.
In Aim 2, we will perform a comprehensive study of this pathway in vivo using young and old mice from colonies of both wildtype and GEMMs with altered levels of NAD+ and HIF-1? throughout the body or in specific tissues such as muscle and brain.
In Aim 3, we will evaluate the efficacy of the best NAD+ modulating compounds (from Aim 1) to prolong healthspan and lifespan in mice. We will also test the best compounds for their efficacy in a gold- standard model of acute gout (a common age-associated inflammatory disease for which there are no effective treatments) thereby paving the way for rapid human clinical trials. The work will have far-reaching implications by changing our understanding of why aging occurs and creating novel therapeutics to prolong human healthspan and longevity.
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|Latorre-Muro, Pedro; Baeza, Josue; Armstrong, Eric A et al. (2018) Dynamic Acetylation of Phosphoenolpyruvate Carboxykinase Toggles Enzyme Activity between Gluconeogenic and Anaplerotic Reactions. Mol Cell 71:718-732.e9|
|Longchamp, Alban; Mirabella, Teodelinda; Arduini, Alessandro et al. (2018) Amino Acid Restriction Triggers Angiogenesis via GCN2/ATF4 Regulation of VEGF and H2S Production. Cell 173:117-129.e14|
|Dai, Han; Sinclair, David A; Ellis, James L et al. (2018) Sirtuin activators and inhibitors: Promises, achievements, and challenges. Pharmacol Ther 188:140-154|
|Rajman, Luis; Chwalek, Karolina; Sinclair, David A (2018) Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence. Cell Metab 27:529-547|
|Das, Abhirup; Huang, George X; Bonkowski, Michael S et al. (2018) Impairment of an Endothelial NAD+-H2S Signaling Network Is a Reversible Cause of Vascular Aging. Cell 173:74-89.e20|
|Schultz, Michael B; Lu, Yuancheng; Braidy, Nady et al. (2018) Assays for NAD+-Dependent Reactions and NAD+ Metabolites. Methods Mol Biol 1813:77-90|
|Wahl, Devin; Solon-Biet, Samantha M; Wang, Qiao-Ping et al. (2018) Comparing the Effects of Low-Protein and High-Carbohydrate Diets and Caloric Restriction on Brain Aging in Mice. Cell Rep 25:2234-2243.e6|
|Cronise, Raymond J; Sinclair, David A; Bremer, Andrew A (2017) Oxidative Priority, Meal Frequency, and the Energy Economy of Food and Activity: Implications for Longevity, Obesity, and Cardiometabolic Disease. Metab Syndr Relat Disord 15:6-17|
|Uddin, Golam Mezbah; Youngson, Neil A; Doyle, Bronte M et al. (2017) Nicotinamide mononucleotide (NMN) supplementation ameliorates the impact of maternal obesity in mice: comparison with exercise. Sci Rep 7:15063|
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