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Pharmacologic inhibition of acetyl-CoA carboxylase (ACC) enzymes, ACC1 and ACC2, offers an attractive therapeutic strategy for nonalcoholic fatty liver disease (NAFLD) through simultaneous inhibition of fatty acid synthesis and stimulation of fatty acid oxidation. However, the effects of ACC inhibition on hepatic mitochondrial oxidation, anaplerosis, and ketogenesis in vivo are unknown. Here, we evaluated the effect of a liver-directed allosteric inhibitor of ACC1 and ACC2 (Compound 1) on these parameters, as well as glucose and lipid metabolism, in control and diet-induced rodent models of NAFLD. Oral administration of Compound 1 preferentially inhibited ACC enzymatic activity in the liver, reduced hepatic malonyl-CoA levels, and enhanced hepatic ketogenesis by 50%. Furthermore, administration for 6 days to high-fructose-fed rats resulted in a 20% reduction in hepatic de novo lipogenesis. Importantly, long-term treatment (21 days) significantly reduced high-fat sucrose diet-induced hepatic steatosis, protein kinase C epsilon activation, and hepatic insulin resistance. ACCi treatment was associated with a significant increase in plasma triglycerides (approximately 30% to 130%, depending on the length of fasting). ACCi-mediated hypertriglyceridemia could be attributed to approximately a 15% increase in hepatic very low-density lipoprotein production and approximately a 20% reduction in triglyceride clearance by lipoprotein lipase (P ≤ 0.05). At the molecular level, these changes were associated with increases in liver X receptor/sterol response element-binding protein-1 and decreases in peroxisome proliferator-activated receptor-α target activation and could be reversed with fenofibrate co-treatment in a high-fat diet mouse model. Conclusion: Collectively, these studies warrant further investigation into the therapeutic utility of liver-directed ACC inhibition for the treatment of NAFLD and hepatic insulin resistance., (© 2018 by the American Association for the Study of Liver Diseases.)

MicroRNAs (miRNAs) have emerged as biomarkers of metabolic status, etiological factors in complex disease, and promising drug targets. Recent reports suggest that miRNAs are critical regulators of pathways underlying the pathophysiology of type 2 diabetes. In this study, we demonstrate by deep sequencing and real-time quantitative PCR that hepatic levels of Foxa2 mRNA and miR-29 are elevated in a mouse model of diet-induced insulin resistance. We also show that Foxa2 and miR-29 are significantly upregulated in the livers of Zucker diabetic fatty (fa/fa) rats and that the levels of both returned to normal upon treatment with the insulin-sensitizing agent pioglitazone. We present evidence that miR-29 expression in human hepatoma cells is controlled in part by FOXA2, which is known to play a critical role in hepatic energy homeostasis. Moreover, we demonstrate that miR-29 fine-tunes FOXA2-mediated activation of key lipid metabolism genes, including PPARGC1A, HMGCS2, and ABHD5. These results suggest that miR-29 is an important regulatory factor in normal metabolism and may represent a novel therapeutic target in type 2 diabetes and related metabolic syndromes., (© 2014 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.)

The purpose of this study was to evaluate the variability of subcutaneous abdominal adipose tissue (AT) dynamics in obese subjects with a wide range of insulin sensitivity (IS) and the correlation between these two metabolic measures. Ten obese (BMI 30-40 kg/m²) nondiabetic subjects with (n = 6) and without (n = 4) the metabolic syndrome were studied following a 12-wk ²H₂O labeling period. Subcutaneous abdominal AT biopsies were collected. Deuterium incorporation into triglyceride (TG)-glycerol and TG-palmitate were measured by gas chromatography-mass spectrometry for the calculation of fractional TG synthesis (fTG) and fractional de novo lipogenesis (fDNL). Muscle IS and insulin-mediated nonesterified fatty acid (NEFA) suppression (a measure for adipose IS) indexes were derived from the oral glucose tolerance test (OGTT). The ability of subcutaneous abdominal AT to synthesize lipids varied significantly in obese subjects (fTG range 7-28%, fDNL range 1.1-4.6%) with significantly lower values (>35% reduction) for both parameters in obese with the metabolic syndrome. fTG correlated positively with muscle IS (r = 0.64, P = 0.04) and inversely with NEFA suppression during the OGTT (r = -0.69, P = 0.03). These results demonstrate a large variability in subcutaneous abdominal AT lipid turnover in obesity. Moreover, a reduced capacity for subcutaneous abdominal AT fat storage is associated with muscle and adipose tissue insulin resistance as well as with the metabolic syndrome, thus identifying a form of obesity at heightened risk for type 2 diabetes and cardiovascular disease.

Studies in animals have documented that, compared with glucose, dietary fructose induces dyslipidemia and insulin resistance. To assess the relative effects of these dietary sugars during sustained consumption in humans, overweight and obese subjects consumed glucose- or fructose-sweetened beverages providing 25% of energy requirements for 10 weeks. Although both groups exhibited similar weight gain during the intervention, visceral adipose volume was significantly increased only in subjects consuming fructose. Fasting plasma triglyceride concentrations increased by approximately 10% during 10 weeks of glucose consumption but not after fructose consumption. In contrast, hepatic de novo lipogenesis (DNL) and the 23-hour postprandial triglyceride AUC were increased specifically during fructose consumption. Similarly, markers of altered lipid metabolism and lipoprotein remodeling, including fasting apoB, LDL, small dense LDL, oxidized LDL, and postprandial concentrations of remnant-like particle-triglyceride and -cholesterol significantly increased during fructose but not glucose consumption. In addition, fasting plasma glucose and insulin levels increased and insulin sensitivity decreased in subjects consuming fructose but not in those consuming glucose. These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults.

Objective: The purpose of this study was to compare an in vivo test of whole-body glycolysis, the deuterated-glucose disposal test (2H-GDT), with insulin sensitivity measured by the euglycemic-hyperinsulinemic glucose clamp and the steady-state plasma glucose (SSPG) test., Research Design and Methods: The 2H-GDT consists of an oral glucose challenge containing deuterated glucose, followed by measurement of heavy water (2H2O) production, which represents whole-body glycolytic disposal of the glucose load. 2H2O production is corrected for ambient insulin concentration as an index of tissue insulin sensitivity. The 2H-GDT was compared with euglycemic-hyperinsulinemic glucose clamps in healthy lean subjects (n = 8) and subjects with the metabolic syndrome (n = 9) and with the SSPG test in overweight (n = 12) and obese (n = 6) subjects., Results: A strong correlation with the clamp was observed for the 75-g and 30-g 2H-GDT (r = 0.95, P < 0.0001 and r = 0.88, P < 0.0001, respectively). The 2H-GDT and clamp studies revealed marked insulin resistance in subjects with metabolic syndrome compared with lean control subjects. The correlation with the clamp was maintained in each group (lean, r = 0.86, P < 0.01; metabolic syndrome, r = 0.81, P < 0.01) for the 75-g test. The 2H-GDT also correlated strongly with the SSPG test (r = -0.87, P < 0.0001) in overweight and obese subjects., Conclusions: The 2H-GDT, which measures whole-body glycolysis in humans in a quantitative manner, correlates highly with the euglycemic-hyperinsulinemic glucose clamp and the SSPG test. Impaired insulin-mediated whole-body glycolysis is a feature of insulin resistance, which provides a means of assessing insulin sensitivity in vivo.