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Dual-agonists activating the peroxisome proliferator-activated receptors alpha and gamma (PPAR𝛼/𝛾) have shown beneficial effects on glucose and lipid metabolism in patients with type 2 diabetes, but their development was discontinued due to unfavorable cardiovascular and/or renal effects. Here we report the design and preclinical evaluation of a molecule that covalently links the PPAR𝛼/𝛾 dual-agonist Tesaglitazar to GLP-1 to allow for the GLP-1 receptor-dependent delivery of Tesaglitazar. GLP-1/Tesaglitazar does not differ from matched GLP-1 in GLP-1R signaling, but shows GLP-1R-dependent PPAR𝛾-RXR heterodimerization with enhanced efficacy to improve body weight, food intake, and glucose metabolism relative to GLP-1 or Tesaglitazar in mice with diet- and genetically-induced obesity. The conjugate fails to affect body weight and glucose metabolism in GLP-1R knockout (ko) mice and shows preserved effects in DIO mice at doses subthreshold for GLP-1 and Tesaglitazar to improve metabolism. Consistent with the GLP-1R expression pattern, LC/MS-based proteomics identified a series of novel PPAR protein targets in the hypothalamus that are acutely upregulated by Tesaglitazar and by GLP-1/Tesaglitazar, but not by treatment with GLP-1. Collectively, our data show that GLP-1/Tesaglitazar improves energy and glucose metabolism with superior efficacy to GLP-1 or Tesaglitazar alone and suggest that this conjugate holds therapeutic value to treat hyperglycemia and insulin resistance.

Summary Uncertainty exists as to whether the glucose-dependent insulinotropic polypeptide receptor (GIPR) should be activated or inhibited for the treatment of obesity. Gipr was recently demonstrated in hypothalamic feeding centers, but the physiological relevance of CNS Gipr remains unknown. Here we show that HFD-fed CNS-Gipr KO mice and humanized (h)GIPR knockin mice with CNS-hGIPR deletion show decreased body weight and improved glucose metabolism. In DIO mice, acute central and peripheral administration of acyl-GIP increases cFos neuronal activity in hypothalamic feeding centers, and this coincides with decreased body weight and food intake and improved glucose handling. Chronic central and peripheral administration of acyl-GIP lowers body weight and food intake in wild-type mice, but shows blunted/absent efficacy in CNS-Gipr KO mice. Also, the superior metabolic effect of GLP-1/GIP co-agonism relative to GLP-1 is extinguished in CNS-Gipr KO mice. Our data hence establish a key role of CNS Gipr for control of energy metabolism., Graphical abstract, Highlights • CNS-Gipr KO mice are protected from diet-induced obesity and glucose intolerance • Acyl-GIP increases cFOS neuronal activity in key hypothalamic feeding centers • Acyl-GIP effects on body weight and food intake are absent/blunted in CNS-mGipr KO mice • GLP-1/GIP dual-agonism loses superior potency over GLP-1 in CNS-mGipr KO mice., Zhang et al. report that CNS GIPR plays a significant role in regulating food intake. They show that treatment with acyl-GIP or with a GLP-1/GIP dual-agonist lowers body weight and food intake in wild-type mice but shows blunted efficacy in CNS-Gipr KO mice.

Dedifferentiation of insulin-secreting β cells in the islets of Langerhans has been proposed to be a major mechanism of β-cell dysfunction. Whether dedifferentiated β cells can be targeted by pharmacological intervention for diabetes remission, and ways in which this could be accomplished, are unknown as yet. Here we report the use of streptozotocin-induced diabetes to study β-cell dedifferentiation in mice. Single-cell RNA sequencing (scRNA-seq) of islets identified markers and pathways associated with β-cell dedifferentiation and dysfunction. Single and combinatorial pharmacology further show that insulin treatment triggers insulin receptor pathway activation in β cells and restores maturation and function for diabetes remission. Additional β-cell selective delivery of oestrogen by Glucagon-like peptide-1 (GLP-1–oestrogen conjugate) decreases daily insulin requirements by 60%, triggers oestrogen-specific activation of the endoplasmic-reticulum-associated protein degradation system, and further increases β-cell survival and regeneration. GLP-1–oestrogen also protects human β cells against cytokine-induced dysfunction. This study not only describes mechanisms of β-cell dedifferentiation and regeneration, but also reveals pharmacological entry points to target dedifferentiated β cells for diabetes remission.

Uncertainty exists as to whether the glucose-dependent insulinotropic polypeptide receptor (GIPR) should be activated or inhibited for the treatment of obesity. Gipr was recently demonstrated in hypothalamic feeding centers, but the physiological relevance of CNS Gipr remains unknown. We show that HFD-fed CNS-Gipr ko mice and humanized (h)GIPR knock-in mice with CNS-hGIPR deletion show improved body weight and glycemia, but these metabolic improvements vanish upon adult-onset Gipr deletion. In DIO mice, acute central administration of acyl-GIP increases cFos neuronal activity in the arcuate, dorsomedial, paraventricular and lateral hypothalamus and leads to improved body weight, food intake, and glycemia. Chronic administration of acyl-GIP improves body weight and food intake in wildtype mice, but shows blunted/absent efficacy in CNS-Gipr ko mice. Also, the superior metabolic effect of GLP-1/GIP co-agonism relative to GLP-1 was extinguished in CNS-Gipr ko mice. Our data establish a key role of CNS Gipr for control of energy metabolism.

Loss of cardiac macroautophagy/autophagy impairs heart function, and evidence accumulates that an increased autophagic flux may protect against cardiovascular disease. We therefore tested the protective capacity of the natural autophagy inducer spermidine in animal models of aging and hypertension, which both represent major risk factors for the development of cardiovascular disease. Dietary spermidine elicits cardioprotective effects in aged mice through enhancing cardiac autophagy and mitophagy. In salt-sensitive rats, spermidine supplementation also delays the development of hypertensive heart disease, coinciding with reduced arterial blood pressure. The high blood pressure-lowering effect likely results from improved global arginine bioavailability and protection from hypertension-associated renal damage. The polyamine spermidine is naturally present in human diets, though to a varying amount depending on food type and preparation. In humans, high dietary spermidine intake correlates with reduced blood pressure and decreased risk of cardiovascular disease and related death. Altogether, spermidine represents a cardio- and vascular- protective autophagy inducer that can be readily integrated in common diets.

Sabrina Schroeder, Andreas Zimmermann, Didac Carmona-Gutierrez, Tobias Eisenberg, Christoph Ruckenstuhl, Aleksandra Andryushkova, Tobias Pendl, Alexandra Harger and Frank Madeo* 1 Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, 8010 Graz, Austria. 2 Division of Endocrinology and Metabolism, Dept. of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria. # These authors contributed equally to this work. * Corresponding Author: F. Madeo, Humboldtstrasse 50; 8010 Graz, Austria; Tel: +43 316 380 8878; Fax: +43 316 380 9898; E-mail: frank.madeo@uni-graz.at

Acetyl-coenzyme A (AcCoA) is a major integrator of the nutritional status at the crossroads of fat, sugar, and protein catabolism. Here we show that nutrient starvation causes rapid depletion of AcCoA. AcCoA depletion entailed the commensurate reduction in the overall acetylation of cytoplasmic proteins, as well as the induction of autophagy, a homeostatic process of self-digestion. Multiple distinct manipulations designed to increase or reduce cytosolic AcCoA led to the suppression or induction of autophagy, respectively, both in cultured human cells and in mice. Moreover, maintenance of high AcCoA levels inhibited maladaptive autophagy in a model of cardiac pressure overload. Depletion of AcCoA reduced the activity of the acetyltransferase EP300, and EP300 was required for the suppression of autophagy by high AcCoA levels. Altogether, our results indicate that cytosolic AcCoA functions as a central metabolic regulator of autophagy, thus delineating AcCoA-centered pharmacological strategies that allow for the therapeutic manipulation of autophagy.

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

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons, which arises from a yet elusive concurrence between genetic and environmental factors. The protein α-synuclein (αSyn), the principle toxic effector in PD, has been shown to interfere with neuronal Ca(2+) fluxes, arguing for an involvement of deregulated Ca(2+) homeostasis in this neuronal demise. Here, we identify the Golgi-resident Ca(2+)/Mn(2+) ATPase PMR1 (plasma membrane-related Ca(2+)-ATPase 1) as a phylogenetically conserved mediator of αSyn-driven changes in Ca(2+) homeostasis and cytotoxicity. Expression of αSyn in yeast resulted in elevated cytosolic Ca(2+) levels and increased cell death, both of which could be inhibited by deletion of PMR1. Accordingly, absence of PMR1 prevented αSyn-induced loss of dopaminergic neurons in nematodes and flies. In addition, αSyn failed to compromise locomotion and survival of flies when PMR1 was absent. In conclusion, the αSyn-driven rise of cytosolic Ca(2+) levels is pivotal for its cytotoxicity and requires PMR1.

As the major lysosomal degradation pathway, autophagy represents the guardian of cellular homeostasis, removing damaged and potentially harmful material and replenishing energy reserves in conditions of starvation. Given its vast physiological importance, autophagy is crucially involved in the process of aging and associated pathologies. Although the regulation of autophagy strongly depends on nutrient availability, specific metabolites that modulate autophagic responses are poorly described. Recently, we revealed nucleo-cytosolic acetyl-coenzyme A (AcCoA) as a phylogenetically conserved inhibitor of starvation-induced and age-associated autophagy. AcCoA is the sole acetyl-group donor for protein acetylation, explaining why pharmacological or genetic manipulations that modify the concentrations of nucleo-cytosolic AcCoA directly affect the levels of protein acetylation. The acetylation of histones and cytosolic proteins inversely correlates with the rate of autophagy in yeast and mammalian cells, respectively, despite the fact that the routes of de novo AcCoA synthesis differ across phyla. Thus, we propose nucleo-cytosolic AcCoA to act as a conserved metabolic rheostat, linking the cellular metabolic state to the regulation of autophagy via effects on protein acetylation.

Summary Healthy aging depends on removal of damaged cellular material that is in part mediated by autophagy. The nutritional status of cells affects both aging and autophagy through as-yet-elusive metabolic circuitries. Here, we show that nucleocytosolic acetyl-coenzyme A (AcCoA) production is a metabolic repressor of autophagy during aging in yeast. Blocking the mitochondrial route to AcCoA by deletion of the CoA-transferase ACH1 caused cytosolic accumulation of the AcCoA precursor acetate. This led to hyperactivation of nucleocytosolic AcCoA-synthetase Acs2p, triggering histone acetylation, repression of autophagy genes, and an age-dependent defect in autophagic flux, culminating in a reduced lifespan. Inhibition of nutrient signaling failed to restore, while simultaneous knockdown of ACS2 reinstated, autophagy and survival of ach1 mutant. Brain-specific knockdown of Drosophila AcCoA synthetase was sufficient to enhance autophagic protein clearance and prolong lifespan. Since AcCoA integrates various nutrition pathways, our findings may explain diet-dependent lifespan and autophagy regulation., Graphical Abstract, Highlights • Acetyl-CoA (AcCoA) metabolism regulates autophagy during aging • Autophagy regulation by AcCoA metabolism acts downstream of nutrient signaling • Brain-specific knockdown of Drosophila AcCoA synthetase prolongs lifespan • Histone point mutations permanently activate autophagy during aging, Autophagy plays a crucial role in healthy aging. By blocking mitochondrial AcCoA production, Eisenberg et al. show that accumulation of nucleocytosolic AcCoA inhibits autophagy and reduces lifespan through a conserved epigenetic mechanism involving histone acetylation of specific autophagy genes in yeast and flies.

Polycystic ovary syndrome (PCOS) is a heterogeneous disease with many different aspects, including hyperandrogenism and metabolic disturbances. Clinical phenotypes show different patterns of steroid hormones that have been investigated to some extent.This study intended to determine the role of the testosterone (TT) to dihydrotestosterone (DHT) ratio (TT/DHT ratio) in PCOS patients and to further assess the correlation of this ratio with hormonal, anthropometric, and metabolic parameters.Serum samples of 275 premenopausal PCOS patients fulfilling Rotterdam criteria and 35 BMI-matched, premenopausal, healthy controls were analyzed for testosterone, DHT, dehydroepiandrosterone (DHEA), and androstenedione using liquid chromatography/mass spectrometry.We measured total levels of testosterone and DHT and calculated unbound hormone levels as well as the ratio of testosterone to DHT. Further, impaired glucose tolerance, basal and stimulated serum insulin levels, metabolic syndrome and insulin resistance according to the homeostatic model assessment (HOMA-IR) were assessed.PCOS patients showed significantly higher levels of TT (P.001), free testosterone (P.001), and free DHT (P.001) compared to healthy controls. The TT/DHT ratio was significantly higher in PCOS patients (P.001). No difference was found for total DHT levels (P = .072). In PCOS patients alone, the TT/DHT ratio was significantly higher in obese patients (P.001) and patients with metabolic syndrome (P.001), impaired glucose tolerance (IGT) (P.001) or insulin resistance (P.001). Significant correlations of the TT/DHT ratio with various adverse anthropometric, hormonal, lipid and liver parameters and parameters of glucose metabolism were found.Our data provide evidence for a strong link between a high TT/DHT ratio and an adverse metabolic phenotype in PCOS patients. This correlation was only found in PCOS patients, suggesting the TT/DHT ratio to be a new biomarker for an adverse metabolic phenotype in PCOS patients.

Introduction: Polycystic ovary syndrome is a heterogeneous disease with many different aspects including hyperandrogenism and metabolic disturbances. Clinical phenotypes show different patterns of steroid hormones that have been investigated to some extent. The steroid hormone cascade involves the metabolic activity of different enzymes, e.g. 5alpha-reductase, responsible for the conversion of testosterone (TT) to dihydrotestosterone (DHT). This study intended to determine the 5alpha-reductase activity in PCOS patients by calculating the TT/DHT ratio and to further assess the correlation of this ratio with hormonal, anthropometric and metabolic parameters. Methods: Serum samples of 275 PCOS patients fulfilling Rotterdam criteria and 35 BMI-matched, healthy controls were analysed for testosterone, dihydrotestosterone, dehydroepiandrosterone and androstenedione using liquid chromatography/mass spectrometry. TT/DHT ratio was calculated in order to reflect 5alpha-reductase activity. Result: PCOS patients showed significantly higher levels of total testosterone (p < 0.001), free testosterone (p < 0.001) and free DHT (p < 0.001) compared to controls. TT/DHT ratio was significantly higher in PCOS patients (p < 0.001), indicating a lower 5alpha-reductase activity. No difference was found for total DHT levels (p = 0.072). In PCOS patients alone, TT/DHT ratio was significantly higher in obese patients (p < 0.001) and patients with metabolic syndrome (p < 0.001), pathologic oGTT (p < 0.001) or insulin resistance (p < 0.001). Significant correlations of the TT/DHT ratio with various adverse anthropometric, hormonal, lipid and liver parameters and parameters of glucose metabolism were found. Conclusion: Our data show a higher TT/DHT ratio in serum of PCOS patients, indicating a lower 5alpha-reductase activity and adverse effects on the clinical and metabolic appearance.