28Aging is associated with an increased risk of cardiovascular disease and death. Here we 29show that oral supplementation of the natural polyamine spermidine extends the lifespan of 30 mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving 31 diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy 32 and mitochondrial respiration, and it also improved the mechano-elastical properties of 33 cardiomyocytes in vivo, coinciding with increased titin phosphorylation and suppressed 34 subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that 35 lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that 36 were fed a high-salt diet, a model for hypertension-induced congestive heart failure, 37 spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and 38 prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the 39 progression to heart failure. In humans, high levels of dietary spermidine, as assessed from 40 food questionnaires, correlated with reduced blood pressure and a lower incidence of 41 cardiovascular disease. Our results suggest a new and feasible strategy for the protection 42 from cardiovascular disease. 43Author's manuscript to Eisenberg et al.

SUMMARY Numerous studies in humans link a nonsynonymous genetic polymorphism (I148M) in adiponutrin (ADPN) to various forms of fatty liver disease and liver cirrhosis. Despite its high clinical relevance, the molecular function of ADPN and the mechanism by which I148M variant affects hepatic metabolism are unclear. Here we show that ADPN promotes cellular lipid synthesis by converting lysophosphatidic acid (LPA) into phosphatidic acid. The ADPN-catalyzed LPA acyltransferase (LPAAT) reaction is specific for LPA and long-chain acyl-CoAs. Wild-type mice receiving a high-sucrose diet exhibit substantial upregulation of Adpn in the liver and a concomitant increase in LPAAT activity. In Adpn-deficient mice, this diet-induced increase in hepatic LPAAT activity is reduced. Notably, the I148M variant of human ADPN exhibits increased LPAAT activity leading to increased cellular lipid accumulation. This gain of function provides a plausible biochemical mechanism for the development of liver steatosis in subjects carrying the I148M variant.

Elevated circulating fatty acids (FAs) contribute to the development of obesity-associated metabolic complications such as insulin resistance (IR) and non-alcoholic fatty liver disease (NAFLD). Hence, reducing adipose tissue lipolysis to diminish the mobilization of FAs and lower their respective plasma concentrations represents a potential treatment strategy to counteract obesity-associated disorders. Here we show that specific inhibition of adipose triglyceride lipase (Atgl) with the chemical inhibitor, Atglistatin, effectively reduces adipose tissue lipolysis, weight gain, IR and NAFLD in mice fed a high-fat diet. Importantly, even long-term treatment does not lead to lipid accumulation in ectopic tissues such as the skeletal muscle or heart. Thus, the severe cardiac steatosis and cardiomyopathy that is observed in genetic models of Atgl deficiency does not occur in Atglistatin-treated mice. Our data validate the pharmacological inhibition of Atgl as a potentially powerful therapeutic strategy to treat obesity and associated metabolic disorders.

Autophagy is a cellular recycling program that retards ageing by efficiently eliminating damaged and potentially harmful organelles and intracellular protein aggregates. Here, we show that the abundance of phosphatidylethanolamine (PE) positively regulates autophagy. Reduction of intracellular PE levels by knocking out either of the two yeast phosphatidylserine decarboxylases (PSD) accelerated chronological ageing-associated production of reactive oxygen species and death. Conversely, the artificial increase of intracellular PE levels, by provision of its precursor ethanolamine or by overexpression of the PE-generating enzyme Psd1, significantly increased autophagic flux, both in yeast and in mammalian cell culture. Importantly administration of ethanolamine was sufficient to extend the lifespan of yeast (Saccharomyces cerevisiae), mammalian cells (U2OS, H4) and flies (Drosophila melanogaster). We thus postulate that the availability of PE may constitute a bottleneck for functional autophagy and that organismal life or healthspan could be positively influenced by the consumption of ethanolamine-rich food.