Pegylated arginine deiminase drives arginine turnover and systemic autophagy to dictate energy metabolism

Obesity is a multi-systemic disorder of energy balance. Despite intense investigation, the determinants of energy homeostasis remain incompletely understood, and efficacious treatments against obesity and its complications are lacking. Here, we demonstrate that conferred arginine iminohydrolysis by the bacterial virulence factor and arginine deiminase

SIRT1 selectively exerts the metabolic protective effects of hepatocyte nicotinamide phosphoribosyltransferase

Calorie restriction abates aging and cardiometabolic disease by activating metabolic signaling pathways, including nicotinamide adenine dinucleotide (NA

SLC2A8 (GLUT8) is a mammalian trehalose transporter required for trehalose-induced autophagy

Trehalose is a disaccharide demonstrated to mitigate disease burden in multiple murine neurodegenerative models. We recently revealed that trehalose rapidly induces hepatic autophagy and abrogates hepatic steatosis by inhibiting hexose transport via the SLC2A family of facilitative transporters. Prior studies, however, postulate that intracellular trehalose is sufficient to induce cellular autophagy. The objective of the current study was to identify the means by which trehalose accesses the hepatocyte cytoplasm, and define the distal signaling mechanisms by which trehalose induces autophagy. We provide gas chromatographic/mass spectrometric, fluorescence microscopic and radiolabeled uptake evidence that trehalose traverses the plasma membrane via SLC2A8 (GLUT8), a homolog of the trehalose transporter-1 (Tret1). Moreover, GLUT8-deficient hepatocytes and GLUT8-deficient mice exposed to trehalose resisted trehalose-induced AMP-activated protein kinase (AMPK) phosphorylation and autophagic induction in vitro and in vivo. Although trehalose profoundly attenuated mTORC1 signaling, trehalose-induced mTORC1 suppression was insufficient to activate autophagy in the absence of AMPK or GLUT8. Strikingly, transient, heterologous Tret1 overexpression reconstituted autophagic flux and AMPK signaling defects in GLUT8-deficient hepatocyte cultures. Together, these data suggest that cytoplasmic trehalose access is carrier-mediated, and that GLUT8 is a mammalian trehalose transporter required for hepatocyte trehalose-induced autophagy and signal transduction

The tetraspanin transmembrane protein CD53 mediates dyslipidemia and integrates inflammatory and metabolic signaling in hepatocytes

Tetraspanins are transmembrane signaling and proinflammatory proteins. Prior work demonstrates that the tetraspanin, CD53/TSPAN25/MOX44, mediates B-cell development and lymphocyte migration to lymph nodes and is implicated in various inflammatory diseases. However, CD53 is also expressed in highly metabolic tissues, including adipose and liver; yet its function outside the lymphoid compartment is not defined. Here, we show that CD53 demarcates the nutritional and inflammatory status of hepatocytes. High-fat exposure and inflammatory stimuli induced CD53 in vivo in liver and isolated primary hepatocytes. In contrast, restricting hepatocyte glucose flux through hepatocyte glucose transporter 8 deletion or through trehalose treatment blocked CD53 induction in fat- and fructose-exposed contexts. Furthermore, germline CD53 deletion in vivo blocked Western diet-induced dyslipidemia and hepatic inflammatory transcriptomic activation. Surprisingly, metabolic protection in CD53 KO mice was more pronounced in the presence of an inciting inflammatory event. CD53 deletion attenuated tumor necrosis factor alpha-induced and fatty acid + lipopolysaccharide-induced cytokine gene expression and hepatocyte triglyceride accumulation in isolated murine hepatocytes. In vivo, CD53 deletion in nonalcoholic steatohepatitis diet-fed mice blocked peripheral adipose accumulation and adipose inflammation, insulin tolerance, and liver lipid accumulation. We then defined a stabilized and trehalase-resistant trehalose polymer that blocks hepatocyte CD53 expression in basal and over-fed contexts. The data suggest that CD53 integrates inflammatory and metabolic signals in response to hepatocyte nutritional status and that CD53 blockade may provide a means by which to attenuate pathophysiology in diseases that integrate overnutrition and inflammation, such as nonalcoholic steatohepatitis and type 2 diabetes

The Effect of Complex Interventions on Depression and Anxiety in Chronic Obstructive Pulmonary Disease: Systematic Review and Meta-Analysis

Background Depression and anxiety are very common in people with chronic obstructive pulmonary disease (COPD) and are associated with excess morbidity and mortality. Patients prefer non-drug treatments and clinical guidelines promote non-pharmacological interventions as first line therapy for depression and anxiety in people with long term conditions. However the comparative effectiveness of psychological and lifestyle interventions among COPD patients is not known. We assessed whether complex psychological and/or lifestyle interventions are effective in reducing symptoms of anxiety and depression in patients with COPD. We then determined what types of psychological and lifestyle interventions are most effective. Methods and Findings Systematic review of randomised controlled trials of psychological and/or lifestyle interventions for adults with COPD that measured symptoms of depression and/or anxiety. CENTRAL, Medline, Embase, PsychINFO, CINAHL, ISI Web of Science and Scopus were searched up to April 2012. Meta-analyses using random effects models were undertaken to estimate the average effect of interventions on depression and anxiety. Thirty independent comparisons from 29 randomised controlled trials (n = 2063) were included in the meta-analysis. Overall, psychological and/or lifestyle interventions were associated with small reductions in symptoms of depression (standardised mean difference −0.28, 95% confidence interval −0.41 to −0.14) and anxiety (standardised mean difference −0.23, 95% confidence interval −0.38 to −0.09). Multi-component exercise training was the only intervention subgroup associated with significant treatment effects for depression (standardised mean difference −0.47, 95% confidence interval −0.66 to −0.28), and for anxiety (standardised mean difference −0.45, 95% confidence interval −0.71 to −0.18). Conclusions Complex psychological and/or lifestyle interventions that include an exercise component significantly improve symptoms of depression and anxiety in people with COPD. Furthermore, multi-component exercise training effectively reduces symptoms of anxiety and depression in all people with COPD regardless of severity of depression or anxiety, highlighting the importance of promoting physical activity in this population

Hepatic arginase 2 (Arg2) is sufficient to convey the therapeutic metabolic effects of fasting

Fasting is known for its beneficial effects on obesity and diabetes-related health complications. Here Zhang et al. show that fasting induces expression of arginase-2 (Arg2) in the liver, and that hepatic Arg2, by suppressing the expression of the regulator of G-protein signalling 16, recapitulates the positive effects of fasting in obesity and diabetes

TFEB-dependent induction of thermogenesis by the hepatocyte SLC2A inhibitor trehalose

<p>The macroautophagy/autophagy-inducing disaccharide, trehalose, has been proposed to be a promising therapeutic agent against neurodegenerative and cardiometabolic diseases. We recently showed that trehalose attenuates hepatic steatosis in part by blocking hepatocyte glucose transport to induce hepatocyte autophagic flux. However, although every major demonstration of trehalose action invokes activating autophagic flux as its primary function, the mechanism of action of trehalose in whole-body energy metabolism remains poorly defined. Here, we demonstrate that trehalose induces hepatocyte TFEB (transcription factor EB)-dependent thermogenesis <i>in vivo</i>, concomitant with upregulation of hepatic and white adipose expression of UCP1 (uncoupling protein 1 [mitochondrial, protein carrier]). Mechanistically, we provide evidence that hepatocyte fasting transcriptional and metabolic responses depend upon PPARGC1A (peroxisome proliferative activated receptor, gamma, coactivator 1 alpha), TFEB, and FGF21 (fibroblast growth factor 21) signaling. Strikingly, hepatocyte-selective TFEB knockdown abrogated trehalose induction of thermogenesis and white adipose tissue UCP1 upregulation <i>in vivo</i>. In contrast, we found that trehalose action on thermogenesis was independent of LEP (leptin) and the autophagy pathway, as there was robust thermogenic induction in trehalose-treated <i>ob/ob, Becn1, Atg16l1</i>, and <i>Epg5</i> mutant mice. We conclude that trehalose induces metabolically favorable effects on whole-body thermogenesis in part via hepatocyte-centered fasting-like mechanisms that appear to be independent of autophagic flux. Our findings elucidate a novel mechanism by which trehalose acts as a metabolic therapeutic agent by activating hepatic fasting responses. More broadly, the hepatic glucose fasting response may be of clinical utility against overnutrition-driven disease, such as obesity and type 2 diabetes mellitus.</p