Background: The risk of cardiovascular disease in type 1 diabetes remains extremely high, despite marked advances in blood glucose control and even the widespread use of cholesterol synthesis inhibitors. Thus, a deeper understanding of insulin regulation of cholesterol metabolism, and its disruption in type 1 diabetes, could reveal better treatment strategies. Methods: To define the mechanisms by which insulin controls plasma cholesterol levels, we knocked down the insulin receptor, FoxO1, and the key bile acid synthesis enzyme, CYP8B1. We measured bile acid composition, cholesterol absorption, and plasma cholesterol. In parallel, we measured markers of cholesterol absorption and synthesis in humans with type 1 diabetes treated with ezetimibe and simvastatin in a double-blind crossover study. Results: Mice with hepatic deletion of the insulin receptor showed marked increases in 12α-hydroxylated bile acids, cholesterol absorption, and plasma cholesterol. This phenotype was entirely reversed by hepatic deletion of FoxO1 . FoxO1 is inhibited by insulin and required for the production of 12α-hydroxylated bile acids, which promote intestinal cholesterol absorption and suppress hepatic cholesterol synthesis. Knockdown of Cyp8b1 normalized 12α-hydroxylated bile acid levels and completely prevented hypercholesterolemia in mice with hepatic deletion of the insulin receptor (n=5–30), as well as mouse models of type 1 diabetes (n=5–22). In parallel, the cholesterol absorption inhibitor, ezetimibe, normalized cholesterol absorption and low-density lipoprotein cholesterol in patients with type 1 diabetes as well as, or better than, the cholesterol synthesis inhibitor, simvastatin (n=20). Conclusions: Insulin, by inhibiting FoxO1 in the liver, reduces 12α-hydroxylated bile acids, cholesterol absorption, and plasma cholesterol levels. Thus, type 1 diabetes leads to a unique set of derangements in cholesterol metabolism, with increased absorption rather than synthesis. These derangements are reversed by ezetimibe, but not statins, which are currently the first line of lipid-lowering treatment in type 1 diabetes. Taken together, these data suggest that a personalized approach to lipid lowering in type 1 diabetes may be more effective and highlight the need for further studies specifically in this group of patients.

Nonalcoholic fatty liver disease (NAFLD) is becoming the most common indication for liver transplantation. The growing prevalence of NAFLD not only increases the demand for liver transplantation, but it also limits the supply of available organs because steatosis predisposes grafts to ischemia/reperfusion injury (IRI) and many steatotic grafts are discarded. We have shown that monoacylglycerol acyltransferase (MGAT) 1, an enzyme that converts monoacylglycerol to diacylglycerol, is highly induced in animal models and patients with NAFLD and is an important mediator in NAFLD‐related insulin resistance. Herein, we sought to determine whether Mogat1 (the gene encoding MGAT1) knockdown in mice with hepatic steatosis would reduce liver injury and improve liver regeneration following experimental IRI. Antisense oligonucleotides (ASO) were used to knockdown the expression of M o gat1 in a mouse model of NAFLD. Mice then underwent surgery to induce IRI. We found that M ogat1 knockdown reduced hepatic triacylglycerol accumulation, but it unexpectedly exacerbated liver injury and mortality following experimental ischemia/reperfusion surgery in mice on a high‐fat diet. The increased liver injury was associated with robust effects on the hepatic transcriptome following IRI including enhanced expression of proinflammatory cytokines and chemokines and suppression of enzymes involved in intermediary metabolism. These transcriptional changes were accompanied by increased signs of oxidative stress and an impaired regenerative response. We have shown that M ogat1 knockdown in a mouse model of NAFLD exacerbates IRI and inflammation and prolongs injury resolution, suggesting that Mogat1 may be necessary for liver regeneration following IRI and that targeting this metabolic enzyme will not be an effective treatment to reduce steatosis‐associated graft dysfunction or failure.

The etiology of diabetic nephropathy in type 2 diabetes is multifactorial. Sustained hyperglycemia is a major contributor, but additional contributions come from the hypertension, obesity, and hyperlipidemia that are also commonly present in patients with type 2 diabetes and nephropathy. The leptin deficient BTBR ob/ob mouse is a model of type 2 diabetic nephropathy in which hyperglycemia, obesity, and hyperlipidemia, but not hypertension, are present. We have shown that reversal of the constellation of these metabolic abnormalities with leptin replacement can reverse the morphologic and functional manifestations of diabetic nephropathy. Here we tested the hypothesis that reversal specifically of the hypertriglyceridemia, using an antisense oligonucleotide directed against ApoC-III, an apolipoprotein that regulates the interactions of VLDL (very low density lipoproteins) with the LDL receptor, is sufficient to ameliorate the nephropathy of Type 2 diabetes. Antisense treatment resulted in reduction of circulating ApoC-III protein levels and resulted in substantial lowering of triglycerides to near-normal levels in diabetic mice versus controls. Antisense treatment did not ameliorate proteinuria or pathologic manifestations of diabetic nephropathy, including podocyte loss. These studies indicate that pathologic manifestations of diabetic nephropathy are unlikely to be reduced by lipid-lowering therapeutics alone, but does not preclude a role for such interventions to be used in conjunction with other therapeutics commonly employed in the treatment of diabetes and its complications.

Lipid droplets (LDs) provide a reservoir for triacylglycerol storage and are a central hub for fatty acid trafficking and signaling in cells. Lipolysis promotes mitochondrial biogenesis and oxidative metabolism via a SIRT1/PGC-1α/PPARα-dependent pathway through an unknown mechanism. Herein, we identify that monounsaturated fatty acids (MUFAs) allosterically activate SIRT1 toward select peptide-substrates such as PGC-1α. MUFAs enhance PGC-1α/PPARα signaling and promote oxidative metabolism in cells and animal models in a SIRT1-dependent manner. Moreover, we characterize the LD protein perilipin 5 (PLIN5), which is known to enhance mitochondrial biogenesis and function, to be a fatty-acid-binding protein that preferentially binds LD-derived monounsaturated fatty acids and traffics them to the nucleus following cAMP/PKA-mediated lipolytic stimulation. Thus, these studies identify the first-known endogenous allosteric modulators of SIRT1 and characterize a LD-nuclear signaling axis that underlies the known metabolic benefits of MUFAs and PLIN5.

Overnutrition increases the proliferation of hematopoietic stem and multipotent progenitor cells (HSPCs) and overproduction of monocyte, resulting in the development of low-grade inflammatory and metabolic phenotypes. One molecule that regulates hematopoietic stem cell proliferation is heparin-binding EGF-like growth factor (HB-EGF). Cellular and oxidative stresses sensitively upregulate the HB-EGF gene expression in the cells. Hypothesis: In this study, we tested the hypothesis that HB-EGF is a crucial regulator for the production of myeloids during metabolic stress associated with overnutrition. Methods and Results: The administration of the HB-EGF antisense oligonucleotide (ASO), which is adequately distributed in bone marrow, in the LDLR KO mice under the Western diet (21% fat and 0.2% cholesterol) downregulated the number of leucocytes and myeloids (neutrophils and monocytes) in peripheral bloodstream. Flow cytometry analysis result indicated that the antisense also downregulated the number of myeloid progenitors (MPCs, CMPs, and GMPs) in the bone marrow and spleen tissues. The HB-EGF knockdown in a mouse system using the loxP-Cre approach also effectively induced downregulation of quantity of myeloid progenitors in the bone marrow and spleen tissues. The HB-EGF antisense effectively reduced the CD68 macrophage content in the liver in the LDLR KO mice under the Western diet. The HB-EGF antisense protected against the development of metabolic disease phenotypes (hyperlipidemia, atherosclerosis, and insulin resistance) in the mice. Conclusion: The results from this study consistently suggested that HB-EGF is a critical regulator for the myeloid production during the metabolic stress environment associated with overnutrition. The study also shows the applicability of the targeting of HB-EGF to prevent or reverse metabolic diseases associated with low-grade inflammation.

Objective- AGT (Angiotensinogen) is the unique precursor of the renin-angiotensin system that is sequentially cleaved by renin and ACE (angiotensin-converting enzyme) to produce Ang II (angiotensin II). In this study, we determined how these renin-angiotensin components interact with megalin in kidney to promote atherosclerosis. Approach and Results- AGT, renin, ACE, and megalin were present in the renal proximal convoluted tubules of wild-type mice. Hepatocyte-specific AGT deficiency abolished AGT protein accumulation in proximal tubules and diminished Ang II concentrations in kidney, while renin was increased. Megalin was most abundant in kidney and exclusively present on the apical side of proximal tubules. Inhibition of megalin by antisense oligonucleotides (ASOs) led to ablation of AGT and renin proteins in proximal tubules, while leading to striking increases of urine AGT and renin concentrations, and 70% reduction of renal Ang II concentrations. However, plasma Ang II concentrations were unaffected. To determine whether AGT and megalin interaction contributes to atherosclerosis, we used both male and female low-density lipoprotein receptor-/- mice fed a saturated fat-enriched diet and administered vehicles (PBS or control ASO) or megalin ASO. Inhibition of megalin did not affect plasma cholesterol concentrations, but profoundly reduced atherosclerotic lesion size in both male and female mice. Conclusions- These results reveal a regulatory role of megalin in the intrarenal renin-angiotensin homeostasis and atherogenesis, positing renal Ang II to be an important contributor to atherosclerosis that is mediated through AGT and megalin interactions.

OBJECTIVE:ApoC-III (apolipoprotein C-III) glycosylation can predict cardiovascular disease risk. Higher abundance of disialylated (apoC-III2) over monosialylated (apoC-III1) glycoforms is associated with lower plasma triglyceride levels. Yet, it remains unclear whether apoC-III glycosylation impacts TRL (triglyceride-rich lipoprotein) clearance and whether apoC-III antisense therapy (volanesorsen) affects distribution of apoC-III glycoforms. Approach and Results: To measure the abundance of human apoC-III glycoforms in plasma over time, human TRLs were injected into wild-type mice and mice lacking hepatic TRL clearance receptors, namely HSPGs (heparan sulfate proteoglycans) or both LDLR (low-density lipoprotein receptor) and LRP1 (LDLR-related protein 1). ApoC-III was more rapidly cleared in the absence of HSPG (t1/2=25.4 minutes) than in wild-type animals (t1/2=55.1 minutes). In contrast, deficiency of LDLR and LRP1 (t1/2=56.1 minutes) did not affect clearance of apoC-III. After injection, a significant increase in the relative abundance of apoC-III2 was observed in HSPG-deficient mice, whereas the opposite was observed in mice lacking LDLR and LRP1. In patients, abundance of plasma apoC-III glycoforms was assessed after placebo or volanesorsen administration. Volanesorsen treatment correlated with a statistically significant 1.4-fold increase in the relative abundance of apoC-III2 and a 15% decrease in that of apoC-III1. The decrease in relative apoC-III1 abundance was strongly correlated with decreased plasma triglyceride levels in patients.CONCLUSIONS:Our results indicate that HSPGs preferentially clear apoC-III2. In contrast, apoC-III1 is more effectively cleared by LDLR/LRP1. Clinically, the increase in the apoC-III2/apoC-III1 ratio on antisense lowering of apoC-III might reflect faster clearance of apoC-III1 because this metabolic shift associates with improved triglyceride levels.

Type 1 diabetes mellitus (T1DM) increases the risk of atherosclerotic cardiovascular disease (CVD) in humans by poorly understood mechanisms. Using mouse models of T1DM-accelerated atherosclerosis, we found that relative insulin deficiency, rather than hyperglycemia, elevated levels of apolipoprotein C3 (APOC3), an apolipoprotein that prevents clearance of triglyceride-rich lipoproteins (TRLs) and their remnants. We then showed that serum APOC3 levels predict incident CVD events in subjects with T1DM in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. To explore underlying mechanisms, we examined the impact of Apoc3 antisense oligonucleotides (ASOs) on lipoprotein metabolism and atherosclerosis in a mouse model of T1DM. Apoc3 ASO treatment abolished the increased hepatic expression of Apoc3 in diabetic mice, resulting in lower levels of TRLs, without improving glycemic control. APOC3 suppression also prevented arterial accumulation of APOC3-containing lipoprotein particles, macrophage foam cell formation, and accelerated atherosclerosis in diabetic mice. Our observations demonstrate that relative insulin deficiency increases APOC3 and that this results in elevated levels of TRLs and accelerated atherosclerosis in a mouse model of T1DM. Because serum levels of APOC3 predicted incident CVD events in the CACTI study, inhibition of APOC3 might reduce CVD risk in patients with T1DM.

Recent studies have identified a genetic variant rs641738 near two genes encoding membrane bound O-acyltransferase domain-containing 7 (MBOAT7) and transmembrane channel-like 4 (TMC4) that associate with increased risk of non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), alcohol-related cirrhosis, and liver fibrosis in those infected with viral hepatitis (Buch et al., 2015; Mancina et al., 2016; Luukkonen et al., 2016; Thabet et al., 2016; Viitasalo et al., 2016; Krawczyk et al., 2017; Thabet et al., 2017). Based on hepatic expression quantitative trait loci analysis, it has been suggested that MBOAT7 loss of function promotes liver disease progression (Buch et al., 2015; Mancina et al., 2016; Luukkonen et al., 2016; Thabet et al., 2016; Viitasalo et al., 2016; Krawczyk et al., 2017; Thabet et al., 2017), but this has never been formally tested. Here we show that Mboat7 loss, but not Tmc4, in mice is sufficient to promote the progression of NAFLD in the setting of high fat diet. Mboat7 loss of function is associated with accumulation of its substrate lysophosphatidylinositol (LPI) lipids, and direct administration of LPI promotes hepatic inflammatory and fibrotic transcriptional changes in an Mboat7-dependent manner. These studies reveal a novel role for MBOAT7-driven acylation of LPI lipids in suppressing the progression of NAFLD.

Liver targeted deletion of FoxO Mice with hepatocyte-targeted deletion of FoxO1, FoxO3 and FoxO4 have been described previously (1). These mice were on a mixed C57BL/6J 129S1 background. Controls were littermates who did not express liver-specific α1-antitrypsin-Cre. Mice were fasted for 4 hours on the day of sacrifice during the dark cycle, and then blood and livers were collected for analysis. We also induced acute deletion of FoxOs in adult mice by injecting them with an adeno-associated virus (AAV8; 1 × 1011viral genomes/mouse) expressing Cre recombinase under control of the Tbg (thyroxine hormone-binding globulin) promoter for liver specificity 4 weeks prior to the end of the experiment. Controls were injected with GFP-AAV8. Mice were fasted for 4 hours on the day of sacrifice. This method has also been described previously (1). Male mice were used for these experiments. The experiments were performed in accordance with the Columbia University Institutional Animal Care and Use Committee (protocol # AAAQ4433).

Angiotensinogen (AGT) is the unique substrate of all angiotensin peptides. We review the recent preclinical research of AGT antisense oligonucleotides (ASOs), a rapidly evolving therapeutic approach. The scope of the research findings not only opens doors for potentially new therapeutics of hypertension and many other diseases, but also provides insights into understanding critical physiological and pathophysiological roles mediated by AGT.

During prolonged fasting, the liver plays a central role in maintaining systemic energy homeostasis by producing glucose and ketones in processes fueled by oxidation of fatty acids liberated from adipose tissue. In mice, this is accompanied by transient hepatic accumulation of glycerolipids. We found that the hepatic expression of monoacylglycerol acyltransferase 1 (Mogat1), an enzyme with monoacylglycerol acyltransferase (MGAT) activity that produces diacyl-glycerol from monoacylglycerol, was significantly increased in the liver of fasted mice compared with mice given ad libitum access to food. Basal and fasting-induced expression of Mogat1 was markedly diminished in the liver of mice lacking the transcription factor PPAR alpha. Suppressing Mogat1 expression in liver and adipose tissue with antisense oligonucleotides (ASOs) reduced hepatic MGAT activity and triglyceride content compared with fasted controls. Surprisingly, the expression of many other PPAR alpha target genes and PPAR alpha activity was also decreased in mice given Mogat1 ASOs. When mice treated with control or Mogat1 ASOs were gavaged with the PPAR alpha ligand, WY-14643, and then fasted for 18 h, WY-14643 administration reversed the effects of Mogat1 ASOs on PPAR alpha target gene expression and liver triglyceride content. In conclusion, Mogat1 is a fasting-induced PPAR alpha target gene that may feed forward to regulate liver PPAR alpha activity during food deprivation.

Fibrosis is the major determinant of morbidity and mortality in patients with nonalcoholic steatohepatitis (NASH) but has no approved pharmacotherapy in part because of incomplete understanding of its pathogenic mechanisms. Here, we report that hepatocyte Notch activity tracks with disease severity and treatment response in patients with NASH and is similarly increased in a mouse model of diet-induced NASH and liver fibrosis. Hepatocyte-specific Notch loss-of-function mouse models showed attenuated NASH-associated liver fibrosis, demonstrating causality to obesity-induced liver pathology. Conversely, forced activation of hepatocyte Notch induced fibrosis in both chow- and NASH diet-fed mice by increasing Sox9-dependent Osteopontin (Opn) expression and secretion from hepatocytes, which activate resident hepatic stellate cells. In a cross-sectional study, we found that OPN explains the positive correlation between liver Notch activity and fibrosis stage in patients. Further, we developed a Notch inhibitor [Nicastrin antisense oligonucleotide (Ncst ASO)] that reduced fibrosis in NASH diet-fed mice. In summary, these studies demonstrate the pathological role and therapeutic accessibility of the maladaptive hepatocyte Notch response in NASH-associated liver fibrosis.

ABSTARCT The hepatic glucose fasting response is gaining traction as a therapeutic pathway to enhance hepatic and whole-host metabolism. However, the mechanisms underlying these metabolic effects remain unclear. Here, we demonstrate the lipoxygenase, ALOXE3, is a novel effector of the thepatic fasting response. We show that ALOXE3 is activated during fasting, glucose withdrawal, and trehalose/trehalose analogue treatment. Hepatocyte-specific ALOXE3 expression reduced weight gain and hepatic steatosis in dietaryand genetically obese (db/db) models. ALOXE3 expression moreover enhanced basal thermogenesis and abrogated insulin resistance in db/db diabetic mice. Targeted metabolomics demonstrated accumulation of the PPARγ ligand, 12-KETE in hepatocytes overexpressing ALOXE3. Strikingly, PPARγ inhibition reversed hepatic ALOXE3-mediated insulin sensitization, suppression of hepatocellular ATP production and oxygen consumption, and gene induction of PPARγ coactivator-1a (PGC1α) expression. Moreover, hepatocyte-specific PPARγ deletion reversed the therapeutic effect of hepatic ALOXE3 expression on diet-induced insulin intolerance. ALOXE3 is therefore a novel effector of the hepatocellular fasting response that leverages both PPARγ-mediated and pleiotropic effects to augment hepatic and whole-host metabolism, and is thus a promising target to ameliorate metabolic disease.

Background: We previously reported an association between higher abundance of disialylated (apoC-III 2 ) over monosialylated (apoC-III 1 ) apoC-III and lower plasma triglyceride (TG) concentrations in three independent studies. Methods: The goal of this study was to get mechanistic insights in the metabolism of apoC-III 1 and apoC-III 2 . First, the relative abundances of human triglyceride-rich lipoproteins (TRL)-associated apoC-III glycoforms in plasma were assessed by mass spectrometric immunoassay (MSIA) over time after injecting human TRL in wild-type mice, mice lacking hepatic heparan sulfate proteoglycans (HSPG), and mice deficient for both low-density lipoprotein receptor (LDLR) and LDLR-Related Protein 1 (LRP-1). Secondly, the relative abundance of plasma apoC-III glycoforms was assessed by MSIA in 11 participants randomized to volanesorsen (apoC-III antisense drug; n=11) or placebo (n=6) treatment for 13 weeks. Results: Kinetic studies revealed that half of TRL-associated apoC-III (total) was rapidly cleared via LDLR and LRP1 (t 1/2 = 16.5 min), and the remaining half via the much slower but higher capacity HSPGs (t 1/2 = 55.5 min). After injection, a significant increase in the relative abundance of apoC-III 2 was observed in HSPG-deficient mice , while no increase in mice lacking LDLR and LRP-1. Clinically, the relative abundance of apoC-III 2 significantly increased (42% increase compared to placebo, p=0.05) and that of apoC-III 1 significantly decreased (15% decrease compared to placebo, p=0.007) in participants randomized to volanesorsen. The decrease in the relative abundance of apoC-III 1 after volanesorsen treatment was strongly correlated with the decrease in TG levels (r=0.63, p=0.006). Conclusions: Our results indicate slower clearance of apoC-III-containing particles through HSPGs, which preferentially clear apoC-III 2. In contrast, apoC-III 2 is less effectively cleared by LDLR/LRP-1 compared to apoC-III 1 . Clinically, the increase in the apoC-III 2 /apoC-III 1 ratio upon antisense lowering of apoC-III might reflect faster clearance of apoC-III 1 as it associates with improved TG levels.

The hepatic glucose fasting response is gaining traction as a therapeutic pathway to enhance hepatic and whole-host metabolism. However, the mechanisms underlying these metabolic effects remain unclear. Here, we demonstrate the epidermal-type lipoxygenase, eLOX3 (encoded by its gene, Aloxe3), is a potentially novel effector of the therapeutic fasting response. We show that Aloxe3 is activated during fasting, glucose withdrawal, or trehalose/trehalose analogue treatment. Hepatocyte-specific Aloxe3 expression reduced weight gain and hepatic steatosis in diet-induced and genetically obese (db/db) mouse models. Aloxe3 expression, moreover, enhanced basal thermogenesis and abrogated insulin resistance in db/db diabetic mice. Targeted metabolomics demonstrated accumulation of the PPARγ ligand 12-KETE in hepatocytes overexpressing Aloxe3. Strikingly, PPARγ inhibition reversed hepatic Aloxe3-mediated insulin sensitization, suppression of hepatocellular ATP production and oxygen consumption, and gene induction of PPARγ coactivator-1α (PGC1α) expression. Moreover, hepatocyte-specific PPARγ deletion reversed the therapeutic effect of hepatic Aloxe3 expression on diet-induced insulin intolerance. Aloxe3 is, therefore, a potentially novel effector of the hepatocellular fasting response that leverages both PPARγ-mediated and pleiotropic effects to augment hepatic and whole-host metabolism, and it is, thus, a promising target to ameliorate metabolic disease.

Metabolic plasticity has been linked to polarized macrophage function, but mechanisms connecting specific fuels to tissue macrophage function remain unresolved. Here we apply a stable isotope tracing, mass spectrometry-based untargeted metabolomics approach to reveal the metabolome penetrated by hepatocyte-derived glucose and ketone bodies. In both classically and alternatively polarized macrophages, [13C]acetoacetate (AcAc) labeled ∼200 chemical features, but its reduced form D-[13C]β-hydroxybutyrate (D-βOHB) labeled almost none. [13C]glucose labeled ∼500 features, and while unlabeled AcAc competed with only ∼15% of them, the vast majority required the mitochondrial enzyme succinyl-coenzyme A-oxoacid transferase (SCOT). AcAc carbon labeled metabolites within the cytoplasmic glycosaminoglycan pathway, which regulates tissue fibrogenesis. Accordingly, livers of mice lacking SCOT in macrophages were predisposed to accelerated fibrogenesis. Exogenous AcAc, but not D-βOHB, ameliorated diet-induced hepatic fibrosis. These data support a hepatocyte-macrophage ketone shuttle that segregates AcAc from D-βOHB, coordinating the fibrogenic response to hepatic injury via mitochondrial metabolism in tissue macrophages.

To determine if the pharmacokinetics and pharmacodynamics of gapmer antisense oligonucleotides (ASOs), containing phosphorothioate backbones and 2-O-methoxyethyl RNA modifications (2-MOE ASOs), can be altered by renal disease, a series of experiments were performed in models of chronic kidney disease (CKD) and acute kidney injury (AKI). In an adenine diet model of CKD, 2-MOE ASO activity in the whole kidney was preserved and the reduction in target RNA was sustained for 2-4 weeks postdose. Additionally, 2-MOE ASO distribution within the kidney was altered in mice with CKD, in that ASO delivery to cortical regions with tubular damage was reduced while distribution to the medulla was increased. Finally, the concentration of 2-MOE ASO in liver of mice with CKD was elevated relative to mice without CKD, indicating a reduction in renal function and ASO excretion can potentially alter the systemic delivery of 2-MOE ASOs. These data were generally reproduced in an aristolochic acid model of AKI, with the exception that 2-MOE ASO activity in the whole kidney was slightly reduced with acute injury. The results from these studies have important implications for the development of 2-MOE ASO therapeutics as both renal and extrarenal 2-MOE ASO pharmacokinetics and pharmacodynamics may be altered in patients with renal disease. Importantly, the underlying mechanisms that alter 2-MOE ASO distribution in the context of kidney disease warrant further examination.

During prolonged fasting, the liver plays a central role in maintaining systemic energy homeostasis by producing glucose and ketones in processes fueled by oxidation of fatty acids liberated from adipose tissue. In mice, this is also accompanied by transient hepatic accumulation of complex lipids in the form of triglycerides. In mice fasted for 24 hours, the hepatic expression of Mogat1 was significantly increased compared to mice given ad libitum access to food. Mogat1 encodes an enzyme with monoacylglycerol (MAG) acyltransferase (MGAT) activity, which is an understudied step in glycerolipid synthesis. Basal and fasting‐induced expression of Mogat1 was markedly diminished in liver of mice lacking the transcription factor peroxisome proliferator‐activated receptor α (PPARα). Suppressing Mogat1 expression with antisense‐oligonucleotides (ASO) reduced hepatic MGAT activity and hepatic triglyceride content compared to fasted ASO control treated mice. Surprisingly, the expression of many other known PPARα target genes (Dgat1, Mgll, Cpt1α, Acadm, and Acadl) was also decreased in mice treated with Mogat1 ASO. We postulated that inhibiting Mogat1 suppressed PPARα activity, potentially by loss of a ligand for PPARα. Fasted mice treated with control or Mogat1 ASO were gavaged with the synthetic PPARα ligand WY‐14643, which reversed the effects of Mogat1 ASO on liver triglyceride content as well as PPARα target gene expression. In conclusion, Mogat1 is a fasting‐induced PPARα target gene and MGAT and may feed forward to regulate liver PPARα activity during fasting.Support or Funding InformationA.J.L. was supported by funds from NIH training grant T32 DK07120. K.S.M is supported by K99 HL136658 and A.M.H. is supported by 17‐IBS‐109 from the American Diabetes Association and R56 DK111735. This work was also funded by R01 DK078187 to B.N.F. The Core services of the Diabetes Research Center (P30 DK020579) and the Nutrition Obesity Research Center (P30 DK56341) at the Washington University School of Medicine also supported this work.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

While several molecular targets are under consideration, mechanistic underpinnings of the transition from uncomplicated nonalcoholic fatty liver disease (NAFLD) to nonalcoholic steatohepatitis (NASH) remain unresolved. Here we apply multiscale chemical profiling technologies to mouse models of deranged hepatic ketogenesis to uncover potential NAFLD driver signatures. Use of stable-isotope tracers, quantitatively tracked by nuclear magnetic resonance (NMR) spectroscopy, supported previous observations that livers of wild-type mice maintained long term on a high-fat diet (HFD) exhibit a marked increase in hepatic energy charge. Fed-state ketogenesis rates increased nearly 3-fold in livers of HFD-fed mice, a greater proportionate increase than that observed for tricarboxylic acid (TCA) cycle flux, but both of these contributors to overall hepatic energy homeostasis fueled markedly increased hepatic glucose production (HGP). Thus, to selectively determine the role of the ketogenic conduit on HGP and oxidative hepatic fluxes, we studied a ketogenesis-insufficient mouse model generated by knockdown of the mitochondrial isoform of 3-hydroxymethylglutaryl-CoA synthase (HMGCS2). In response to ketogenic insufficiency, TCA cycle flux in the fed state doubled and HGP increased more than 60%, sourced by a 3-fold increase in glycogenolysis. Finally, high-resolution untargeted metabolomics and shotgun lipidomics performed using ketogenesis-insufficient livers in the fed state revealed accumulation of bis(monoacylglycero)phosphates, which also accumulated in livers of other models commonly used to study NAFLD. In summary, natural and interventional variations in ketogenesis in the fed state strongly influence hepatic energy homeostasis, glucose metabolism, and the lipidome. Importantly, HGP remains tightly linked to overall hepatic energy charge, which includes both terminal fat oxidation through the TCA cycle and partial oxidation via ketogenesis.