Lifespan-increasing drug nordihydroguaiaretic acid inhibits p300 and activates autophagy.

Aging is characterized by the progressive loss of physiological function in all organisms. Remarkably, the aging process can be modulated by environmental modifications, including diet and small molecules. The natural compound nordihydroguaiaretic acid (NDGA) robustly increases lifespan in flies and mice, but its mechanism of action remains unclear. Here, we report that NDGA is an inhibitor of the epigenetic regulator p300. We find that NDGA inhibits p300 acetyltransferase activity in vitro and suppresses acetylation of a key p300 target in histones (i.e., H3K27) in cells. We use the cellular thermal shift assay to uniquely demonstrate NDGA binding to p300 in cells. Finally, in agreement with recent findings indicating that p300 is a potent blocker of autophagy, we show that NDGA treatment induces autophagy. These findings identify p300 as a target of NDGA and provide mechanistic insight into its role in longevity.

Metabolic reprogramming of human CD8+ memory T cells through loss of SIRT1.

The expansion of CD8+CD28- T cells, a population of terminally differentiated memory T cells, is one of the most consistent immunological changes in humans during aging. CD8+CD28- T cells are highly cytotoxic, and their frequency is linked to many age-related diseases. As they do not accumulate in mice, many of the molecular mechanisms regulating their fate and function remain unclear. In this paper, we find that human CD8+CD28- T cells, under resting conditions, have an enhanced capacity to use glycolysis, a function linked to decreased expression of the NAD+-dependent protein deacetylase SIRT1. Global gene expression profiling identified the transcription factor FoxO1 as a SIRT1 target involved in transcriptional reprogramming of CD8+CD28- T cells. FoxO1 is proteasomally degraded in SIRT1-deficient CD8+CD28- T cells, and inhibiting its activity in resting CD8+CD28+ T cells enhanced glycolytic capacity and granzyme B production as in CD8+CD28- T cells. These data identify the evolutionarily conserved SIRT1-FoxO1 axis as a regulator of resting CD8+ memory T cell metabolism and activity in humans.

Ketogenic Diet Reduces Midlife Mortality and Improves Memory in Aging Mice.

Ketogenic diets recapitulate certain metabolic aspects of dietary restriction such as reliance on fatty acid metabolism and production of ketone bodies. We investigated whether an isoprotein ketogenic diet (KD) might, like dietary restriction, affect longevity and healthspan in C57BL/6 male mice. We find that Cyclic KD, KD alternated weekly with the Control diet to prevent obesity, reduces midlife mortality but does not affect maximum lifespan. A non-ketogenic high-fat diet (HF) fed similarly may have an intermediate effect on mortality. Cyclic KD improves memory performance in old age, while modestly improving composite healthspan measures. Gene expression analysis identifies downregulation of insulin, protein synthesis, and fatty acid synthesis pathways as mechanisms common to KD and HF. However, upregulation of PPARα target genes is unique to KD, consistent across tissues, and preserved in old age. In all, we show that a non-obesogenic ketogenic diet improves survival, memory, and healthspan in aging mice.

Shoulder exostoses in hereditary multiple exostoses: probability of surgery and malignant change.

HYPOTHESIS: Patients with hereditary multiple exostoses (HME) in association with palpable shoulder exostoses are more severely affected by their disease. MATERIALS AND METHODS: From a prospective database of 78 families with HME identified, 172 patients were identified. Demographic details, deformity, functional scores, standing height, number of exostoses, site, exostosin genotype (EXT1 and EXT2), surgical excision, and malignant change were recorded. Nonparametric tests were used to compare patients with and without shoulder exostoses (clavicle, scapula, and humerus). RESULTS: There were 5361 palpable exostoses, of which 14% were of the shoulder and were present in 145 patients (84.3%). There was a younger mean age (26.8 vs 37.9 years) and a male predominance in those individuals with shoulder exostoses (P = .0005). Patients with shoulder exostoses had significantly worse disease (P < .05). EXT1 mutations were more commonly observed in those with shoulder exostoses (odds ratio [OR], 20.6; 95% confidence interval [CI], 11.2-28.5; P = .001). The likelihood of surgical excision was greater in those with shoulder exostoses (OR, 2.8) and highest for scapular exostoses (OR, 3.7). Risk factors for surgical excision of shoulder exostoses were younger age (P = .03) and male gender (P < .008). Seven chondrosarcomas occurred, 2 scapular and a proximal humeral. The probability of malignant change of was highest for palpable scapular exostoses relative to any other anatomic site (OR, 12.3; P = .05). CONCLUSION: Shoulder exostoses have a male predominance, and patients are more likely to have an EXT1 mutation. The presence of shoulder exostoses could serve as a tool to identify those individuals at high probability of malignant change. DISCUSSION: The existence of shoulder exostoses identifies those individuals with a high probability of having an EXT1 genotype (OR 20.6, 94.4% sensitivity, 84.8% positive predictive value), which is associated with sarcomatous change.