Malonylation of Acetyl-CoA carboxylase 1 promotes hepatic steatosis and is attenuated by ketogenic diet in NAFLD.

Protein post-translational modifications (PTMs) participate in important bioactive regulatory processes and therefore can help elucidate the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Here, we investigate the involvement of PTMs in ketogenic diet (KD)-improved fatty liver by multi-omics and reveal a core target of lysine malonylation, acetyl-coenzyme A (CoA) carboxylase 1 (ACC1). ACC1 protein levels and Lys1523 malonylation are significantly decreased by KD. A malonylation-mimic mutant of ACC1 increases its enzyme activity and stability to promote hepatic steatosis, whereas the malonylation-null mutant upregulates the ubiquitination degradation of ACC1. A customized Lys1523ACC1 malonylation antibody confirms the increased malonylation of ACC1 in the NAFLD samples. Overall, the lysine malonylation of ACC1 is attenuated by KD in NAFLD and plays an important role in promoting hepatic steatosis. Malonylation is critical for ACC1 activity and stability, highlighting the anti-malonylation effect of ACC1 as a potential strategy for treating NAFLD.

Greater Phosphorylation of AMPK and Multiple AMPK Substrates in the Skeletal Muscle of 24-Month-Old Calorie Restricted Compared to Ad-Libitum Fed Male Rats.

AMP-activated protein kinase (AMPK), a highly conserved, heterotrimeric serine/threonine kinase with critical sensory and regulatory functions, is proposed to induce antiaging actions of caloric restriction (CR). Although earlier studies assessed CR's effects on AMPK in rodent skeletal muscle, the scope of these studies was narrow with a limited focus on older animals. This study's purpose was to fill important knowledge gaps related to CR's influence on AMPK in skeletal muscle of older animals. Therefore, using epitrochlearis muscles from 24-month-old ad-libitum fed (AL) and CR (consuming 65% of AL intake for 8 weeks), male Fischer-344 × Brown Norway F1 rats, we determined: (a) AMPK Thr172 phosphorylation (a key regulatory site) by immunoblot; (b) AMPKα1 and AMPKα2 activity (representing the 2 catalytic α-subunits of AMPK), and AMPKγ3 activity (representing AMPK complexes that include the skeletal muscle-selective regulatory γ3 subunit) using enzymatic assays; (c) phosphorylation of multiple protein substrates that are linked to CR-related effects (acetyl-CoA carboxylase [ACC], that regulates lipid oxidation; Beclin-1 and ULK1 that are autophagy regulatory proteins; Raptor, mTORC1 complex protein that regulates autophagy; TBC1D1 and TBC1D4 that regulate glucose uptake) by immunoblot; and (d) ATP and AMP concentrations (key AMPK regulators) by mass spectrometry. The results revealed significant CR-associated increases in the phosphorylation of AMPKThr172 and 4 AMPK substrates (ACC, Beclin-1, TBC1D1, and TBC1D4), without significant diet-related differences in ATP or AMP concentration or AMPKα1-, AMPKα2-, or AMPKγ3-associated activity. The enhanced phosphorylation of multiple AMPK substrates provides novel mechanistic insights linking AMPK to functionally important consequences of CR.

Lycium barbarum Polysaccharide Regulates the Lipid Metabolism and Alters Gut Microbiota in High-Fat Diet Induced Obese Mice.

Bioactive compounds provide new insights into the prevention and treatment of obesity. Lycium barbarum polysaccharide (LBP), a biological macromolecule extracted from Goji berry, has displayed potential for regulating lipid metabolism. However, the relationship between gut microbiota regulation and lipid metabolism is not entirely clear. In the present study, 50, 100, and 150 mg/kg LBP were intragastrically administered to C57BL/6J male mice fed with a high-fat diet simultaneously lasting for twelve weeks. The results showed that 150 mg/kg LBP showed significant results and all doses of LBP feeding (50, 100, 150 mg/kg) remarkably decreased both serum and liver total cholesterol (TC) and triglyceride (TG) levels. Treatment of 150 mg/kg LBP seems to be more effective in weight loss, lowering free fatty acid (FFA) levels in serum and liver tissues of mice. LBP feeding increased the gene expression of adiponectin and decreased the gene expression of peroxisome proliferator-activated receptor γ, Cluster of Differentiation 36, acetyl-coA carboxylase, and fatty acid synthase in a dose-dependent manner. In addition, the 16s rDNA Sequencing analysis showed that 150 mg/kg LBP feeding may significantly increase the richness of gut microbiota by up-regulation of the ACE and Chao1 index and altered ß-diversity among groups. Treatment of 150 mg/kg LBP feeding significantly regulated the microbial distribution by decreasing the relative abundance of Firmicutes and increasing the relative abundance of Bacteroidetes at the phylum level. Furthermore, the relative abundance of Faecalibaculum, Pantoea, and uncultured_bacterium_f_Muribaculaceae at the genus level was significantly affected by LBP feeding. A significant correlation was observed between body weight, TC, TG, FFA and bile acid and phyla at the genus level. The above results indicate that LBP plays a vital role in preventing obesity by co-regulating lipid metabolism and gut microbiota, but its effects vary with the dose.

Capparis spinosa improves non-alcoholic steatohepatitis through down-regulating SREBP-1c and a PPARα-independent pathway in high-fat diet-fed rats.

OBJECTIVE: Non-alcoholic steatohepatitis (NASH) has become a global medical problem. Currently, there is no approved pharmacologic treatment for this condition. Previous studies have suggested that in the pathogenesis of this disease, regulatory pathways associated with de novo lipogenesis and ß-oxidation pathways genes are misregulated. Capparis spinosa (CS) belongs to the family of Capparidaceae and is a traditional plant used to treat various diseases, particularly dyslipidemia. The compounds and extracts of this plant in In vivo and in vitro studies resulted in a reduction in lipid profiles and glucose. However, the mechanism of these effects remains unknown. This study aimed to evaluate the effects of (CS) fruit extract on NASH compared to fenofibrate and explored the related molecular mechanism. RESULTS: In the rats (n = 40) model of NASH, biochemical and histopathological examinations showed that liver steatosis, inflammation, and hepatic fibrosis were markedly attenuated in response to CS and fenofibrate interventions. At the molecular level, CS treatment down-regulated sterol regulatory element-binding protein-1c (SREBP-1c) (p < 0.001), acetyl-CoA carboxylase (ACC) (p < 0.001), and up-regulated Carnitine palmitoyltransferase I (CPT1) expression (p < 0.001). In conclusion, CS has favorable therapeutic effects for NASH, which was associated with ameliorating steatosis and fibrosis via regulation of the DNL and ß-oxidation pathway genes.

Gestational bisphenol A exposure impairs hepatic lipid metabolism by altering mTOR/CRTC2/SREBP1 in male rat offspring.

Lipid metabolism is an important biochemical process in the body. Recent studies have found that environmental endocrine disruptors play an important role in the regulation of lipid metabolism. Bisphenol A (BPA), a common environmental endocrine disruptor, has adverse effects on lipid metabolism, but the mechanism is still unclear. This study aimed to investigate the effects of gestational BPA exposure on hepatic lipid metabolism and its possible mechanism in male offspring. The pregnant Sprague-Dawley rats were exposed to BPA (0, 0.05, 0.5, 5 mg/kg/day) from day 5 to day 19 of gestation to investigate the levels of triglyceride (TG) and total cholesterol (TC), and the expression of liver lipid metabolism-related genes in male offspring rats. The results showed that compared with the control group, the TG and TC levels in serum and liver in BPA-exposed groups was increased. And the expressions of liver fatty acid oxidation related genes, such as peroxisome proliferators-activated receptor α (PPARα) and carnitine palmitoyl transferase 1α (CPT1α), were down-regulated. However, the expressions of fatty acid synthesis related genes, such as sterol regulatory element binding proteins 1 (SREBP-1), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD-1), were up-regulated. The increased protein levels of mTOR and p-CRTC2 suggested that CREB-regulated transcription coactivator 2 (CRTC2) might be an important mediator in the mTOR/SREBP-1 pathway. In conclusion, these results demonstrated that mTOR/CRTC2/SREBP-1 could be affected by gestational BPA exposure, which may involve in the lipid metabolic disorders in later life.

Organic chromium derived from the chelation of Ganoderma lucidum polysaccharide and chromium (III) alleviates metabolic syndromes and intestinal microbiota dysbiosis induced by high-fat and high-fructose diet.

Organic chromium is of great interest and has become an important chromium supplement resource in recent years because of its low toxicity and easy absorption. In our previous study, we synthesized a novel organic chromium [GLP-Cr] through the chelation of Ganoderma lucidum polysaccharide and chromium (III). The purpose of this study was to investigate the beneficial effects of GLP-Cr on the improvement of metabolic syndromes (MetS) in mice fed with a high-fat and high-fructose diet (HFHFD) and its mechanism of action. The results indicated that oral administration of GLP-Cr inhibited the excessive exaltation of body weight, glucose tolerance, fasting blood glucose and lipid levels, hepatic total cholesterol (TC), triglyceride (TG) levels caused by HFHFD. Besides, 16S rRNA amplicon sequencing showed that GLP-Cr intervention evidently ameliorated intestinal microbiota dysbiosis by changing the proportions of some intestinal microbial phylotypes. In addition, correlation network-based analysis indicated that the key intestinal microbial phylotypes were closely related to biochemical parameters associated with MetS under GLP-Cr intervention. Liver metabolomics analysis suggested that GLP-Cr intervention significantly regulated the levels of some biomarkers involved in alpha-linolenic acid metabolism, fatty acid biosynthesis, steroid hormone biosynthesis, glycerophospholipid metabolism, glycerolipid metabolism, steroid hormone biosynthesis, primary bile acid biosynthesis, and so on. Moreover, GLP-Cr intervention regulated liver mRNA levels of key genes associated with glucose and lipid metabolism. The mRNA level of glucose transporter type 4 (Glut4) was markedly increased by GLP-Cr intervention, and the mRNA levels of phosphoenolpyruvate carboxykinase (Pepck) and glucose-6-phosphatase (G6Pase) in the liver were significantly decreased. Meanwhile, GLP-Cr intervention significantly decreased hepatic mRNA levels of cluster of differentiation 36 (Cd36), acetyl-CoA carboxylase 1 (Acc1) and sterol regulatory element binding protein-1c (Srebp-1c), indicating that GLP-Cr intervention inhibited the excessive accumulation of free fatty acids in the liver. These findings suggest that the prevention of hyperglycemia and dyslipidemia by GLP-Cr may be closely related to the regulation of gut microbial composition and hepatic metabolic pathways, thus GLP-Cr can be serving as a functional component in the prevention of MetS.

Obesity promotes lipid accumulation in mouse cartilage-A potential role of acetyl-CoA carboxylase (ACC) mediated chondrocyte de novo lipogenesis.

Obesity promotes the development of osteoarthritis (OA). It is also well-established that obesity leads to excessive lipid deposition in nonadipose tissues, which often induces lipotoxicity. The objective of this study was to investigate changes in the levels of various lipids in mouse cartilage in the context of obesity and determine if chondrocyte de novo lipogenesis is altered. We used Oil Red O to determine the accumulation of lipid droplets in cartilage from mice fed high-fat diet (HFD) or low-fat diet (LFD). We further used mass spectrometry-based lipidomic analyses to quantify levels of different lipid species. Expression of genes involving in fatty acid (FA) uptake, synthesis, elongation, and desaturation were examined using quantitative polymerase chain reaction. To further study the potential mechanisms, we cultured primary mouse chondrocytes under high-glucose and high-insulin conditions to mimic the local microenvironment associated with obesity and subsequently examined the abundance of cellular lipid droplets. The acetyl-CoA carboxylase (ACC) inhibitor, ND-630, was added to the culture medium to examine the effect of inhibiting de novo lipogenesis on lipid accumulation in chondrocytes. When compared to the mice receiving LFD, the HFD group displayed more chondrocytes with visible intracellular lipid droplets. Significantly higher amounts of total FAs were also detected in the HFD group. Five out of six significantly upregulated FAs were ω-6 FAs, while the two significantly downregulated FAs were ω-3 FAs. Consequently, the HFD group displayed a significantly higher ω-6/ω-3 FA ratio. Ether linked phosphatidylcholine was also found to be higher in the HFD group. Fatty acid desaturase (Fad1-3), fatty acid-binding protein 4 (Fabp4), and fatty acid synthase (Fasn) transcripts were not found to be different between the treatment groups and fatty acid elongase (Elovl1-7) transcripts were undetectable in cartilage. Ceramide synthase 2 (Cers-2), the only transcript found to be changed in these studies, was significantly upregulated in the HFD group. In vitro, chondrocytes upregulated de novo lipogenesis when cultured under high-glucose, high-insulin conditions, and this observation was associated with the activation of ACC, which was attenuated by the addition of ND-630. This study provides the first evidence that lipid deposition is increased in cartilage with obesity and that this is associated with the upregulation of ACC-mediated de novo lipogenesis. This was supported by our observation that ACC inhibition ameliorated lipid accumulation in chondrocytes, thereby suggesting that ACC could potentially be targeted to treat obesity-associated OA.

No fitness cost associated with Asn-2041-Ile mutation in winter wild oat (Avena ludoviciana) seed germination under various environmental conditions.

Knowledge about the fitness cost imposed by herbicide resistance in weeds is instrumental in devising integrated management methods. The present study investigated the germination response of ACCase-resistant (R) and susceptible (S) winter wild oat under different environmental conditions. The DNA of the plants was sequenced after being extracted and purified. The segregated F2 seeds were subjected to various temperatures, water potentials, NaCl concentrations, different pHs, darkness conditions, and burial depths. The results of the sequencing indicated that Ile-2041-Asn mutation is responsible for the evolution of resistance in the studied winter wild oat plants. The seeds were able to germinate over a wide range of temperatures, osmotic potentials, NaCl concentrations, and pHs. Germination percentage of R and S seeds under dark and light conditions was similar and ranged from 86.3 to 88.3%. The highest emergence percentage for both R and S plants was obtained in 0, 1, and 2 cm depths and ranged from 66.6 to 70.3%. In overall, no differences were observed in the germination response between the R and S winter wild oat plants under all studied conditions. No fitness cost at seed level indicates that control of R winter wild oats is more difficult, and it is essential to adopt crop and herbicide rotation to delay the further evolution of resistance.

WZ66, a novel acetyl-CoA carboxylase inhibitor, alleviates nonalcoholic steatohepatitis (NASH) in mice.

The global prevalence of nonalcoholic steatohepatitis (NASH) increases incredibly. NASH ends up to advanced liver disease, which is highly threatening to human health. Currently, treatment of NASH is very limited. Acetyl-CoA carboxylases (ACC1/ACC2) are proved as effective drug targets for NASH. We aimed to develop novel ACC inhibitors and evaluate their therapeutic value for NASH prevention. ACC inhibitors were obtained through structure-based drug design, synthesized, screened from ACC enzymatic measurement platform and elucidated in cell culture-based assays and animal models. The lipidome and microbiome analysis were integrated to assess the effects of WZ66 on lipids profiles in liver and plasma as well as gut microbiota in the intestine. WZ66 was identified as a novel ACC1/2 inhibitor. It entered systemic circulation rapidly and could accumulate in liver. WZ66 alleviated NASH-related liver features including steatosis, Kupffer cells and hepatic stellate cells activation in diet-induced obese mice. The triglycerides (TGs) and other lipids including diglycerides (DGs), phosphatidylcholine (PC) and sphingomyelin (SM) were decreased in WZ66-treated mice as evidenced by lipidome analysis in livers. The lipids profiles in plasma were also altered with WZ66 treatment. Plasma TG were moderately increased, while the activation of SREBP1c was not detected. WZ66 also downregulated the abundance of Allobaculum, Mucispirillum and Prevotella genera as well as Mucispirillum schaedleri species in gut microbiota. WZ66 is an ideal lead compound and a potential drug candidate deserving further investigation in the therapeutics of NASH.

Regulation of fatty acid oxidation of the heart by MCD and ACC during contractile stimulation.

We tested the hypothesis that the level of malonyl-CoA, as well as the corresponding rate of total fatty acid oxidation of the heart, is regulated by the opposing actions of acetyl-CoA carboxylase (ACC) and malonyl-CoA decarboxylase (MCD). We used isolated working rat hearts perfused under physiological conditions. MCD in heart homogenates was measured specifically by (14)CO(2) production from [3-(14)C]malonyl-CoA, and ACC was measured specifically based on the portion of total carboxylase that is citrate sensitive. Increased heart work (1 microM epinephrine + 40% increase in afterload) elicited a 40% increase in total beta-oxidation of exogenous plus endogenous lipids, accompanied by a 33% decrease in malonyl-CoA. The basal activity and citrate sensitivity of ACC (reflecting its phosphorylation state) and citrate content were unchanged. AMP levels were also unchanged. MCD activity, when measured at a subsaturating concentration of malonyl-CoA (50 microM), was increased by 55%. We conclude that physiological increments in AMP during the work transition are insufficient to promote ACC phosphorylation by AMP-stimulated protein kinase. Rather, increased fatty acid oxidation results from increased malonyl-CoA degradation by MCD.