Lipogenesis Genes Research Articles

Hepatic and Pancreatic Cellular Response to Early Life Nutritional Mismatch.

To determine the basis for perinatal nutritional mismatch causing metabolic dysfunction associated steatotic liver disease (MASLD) and diabetes mellitus, we examined adult phenotype, hepatic transcriptome, and pancreatic β-islet function. In prenatal caloric restricted rat with intrauterine growth restriction (IUGR) and postnatal exposure to high fat with fructose (HFhf) or high carbohydrate (RC), we investigated male and female IUGR-Hfhf and IUGR-RC, versus HFhf and CON offspring. Males more than females displayed adiposity, glucose intolerance, insulin resistance, hyperlipidemia, hepatomegaly with hepatic steatosis. Male hepatic triglyceride synthesis, de novo lipogenesis genes increased, while female lipolysis, β-oxidation, fatty acid efflux, and FGF21 genes increased. IUGR-HFhf males demonstrated reduced β-islets insulin and humanin, and type1 diabetes mellitus human amniotic fluid increased humanin. Humanin suppression disabled glucose stimulated insulin, ATP production, with apoptotic diminished β-islet viability. Humanin and FGF21 may reverse perinatal nutritional mismatched phenotype, by restoring functional β-islets and preventing MASLD and diabetes mellitus.

Design, synthesis and biological evaluation of Alisol B derivatives for potential treatment of non-alcoholic steatohepatitis.

Non-alcoholic fatty liver disease (NAFLD), also known as metabolic dysfunction- associated with fatty liver disease (MAFLD), is one of the most prevalent chronic liver diseases globally. NAFLD is characterized by the accumulation of liver fat unrelated to excessive alcohol consumption. Non-alcoholic steatohepatitis (NASH) is the disease progression of NAFLD and could develop into cirrhosis and hepatocellular carcinoma. In previous studies, the preclinical efficacy of alisol B and alisol B 23-acetate against NASH and metabolic syndrome was identified. However, there is a paucity of literature pertaining to the specialized structural optimization of alisol B for the treatment of NASH. In this study, a series of alisol B derivatives (1-21) were designed, synthesized and evaluated in order to improve the activity of alisol B and to obtain candidate compounds for treating NASH. The effects of the synthesized compounds on de novo lipogenesis and α-SMA gene expression were tested to explore the preliminary structure-activity relationship (SAR). Compounds 14 and 21 were selected for further in vivo investigation. The high-fat diet plus carbon tetrachloride (HFD+CCl4)-induced NASH mice model was employed for biological evaluation in vivo. Compounds 14 and 21 effectively improved hepatic steatosis, ballooning, inflammatory infiltration, and hepatic fibrosis in the livers of HFD+CCl4 mice. Thus, 14 and 21 are promising lead compounds for the treatment of NASH.

The RNA-binding protein HuR impairs adipose tissue anabolism in pancreatic cancer cachexia.

Cachexia is defined by chronic loss of fat and muscle, is a frequent complication of pancreatic ductal adenocarcinoma (PDAC), and negatively impacts patient outcomes. Nutritional supplementation cannot fully reverse tissue wasting, and the mechanisms underlying this phenotype are unclear. This work aims to define the relative contributions of catabolism and anabolism to adipose wasting in PDAC-bearing mice. Human antigen R (HuR) is an RNA-binding protein recently shown to suppress adipogenesis. We hypothesize that fat wasting results from a loss of adipose anabolism driven by increased HuR activity in adipocytes of PDAC-bearing mice. Adult C57BL/6J mice received orthotopic PDAC cell (Kras G12D ; p53 R172H/+ ; Pdx1-cre) (OT-PDAC) or PBS (sham) injections. Mice exhibiting moderate cachexia (9 days after injection) were fasted for 24h, or fasted 24h and refed 24h before euthanasia. A separate cohort of PDAC mice were treated with an established HuR inhibitor (KH-3, 100 mg/kg) and subjected to the fast/refeed paradigm. We analyzed body mass, gross fat pad mass, and adipose tissue mRNA expression. We quantified lipolytic rate as the normalized quantity of glycerol released from 3T3-L1 adipocytes in vitro, and gonadal fat pads (gWAT) ex vivo. 3T3-L1 adipocytes treated with PDAC cell conditioned media (CM) liberated less triglyceride into the culture media than control-treated adipocytes (-28.1%) and had lower expression of lipolysis and lipogenesis genes than control cells. PDAC gWAT cultured ex vivo displayed decreased lipolysis compared to sham gWAT (-54.7%). PDAC and sham mice lost equivalent fat mass after a 24h fast, however, PDAC mice could not restore inguinal fat pads (iWAT) (-40.5%) or gWAT (-31.8%) mass after refeeding. RNAseq revealed 572 differentially expressed genes in gWAT from PDAC compared to sham mice. Downregulated genes (n=126) were associated with adipogenesis (adj p=0.05), and expression of adipogenesis master regulators Pparg and Cebpa were reduced in gWAT from PDAC mice. Immunohistochemistry revealed increased HuR staining in gWAT (+74.9%) and iWAT (+41.2%) from PDAC mice. Inhibiting HuR binding restored lipogenesis in refed animals with a concomitant increase in iWAT mass (+131.7%) and genes regulating adipogenesis (Pparγ, Cebpa, Retn, Adipoq, Fasn). Our work highlights deficient adipose anabolism as a driver of wasting in 3T3-L1 adipocytes treated with PDAC conditioned media and OT-PDAC mice. The small molecule KH3, which disrupts HuR binding, was sufficient to restore adipogenic and lipogenic gene expression and prevent adipose wasting. This highlights HuR as a potentially targetable regulatory node for adipose anabolism in cancer cachexia.

The Putative Antilipogenic Role of NRG4 and ERBB4: First Expression Study on Human Liver Samples.

Epidermal growth factor receptor 4 (ERBB4) and neuregulin 4 (NRG4) have been shown to reduce steatosis and prevent the development of non-alcoholic steatohepatitis in mouse models, but little to nothing is known about their role in non-alcoholic fatty liver disease (NAFLD) in humans. This study is the first to investigate the expression of ERBB4 and NRG4 mRNAs and their role in lipid metabolism in the livers of individuals with obesity, type 2 diabetes and biopsy-proven NAFLD. Liver biospecimens were obtained intraoperatively from 80 individuals. Quantitative reverse transcription polymerase chain reaction was used to measure the expression levels of mRNAs ERBB4 and NRG4, as well as key lipogenesis genes in the liver tissue of the donors. Histological analysis was conducted on liver biopsies from 36 subjects, and the levels of the examined transcripts were compared with the stage of NAFLD. In individuals with elevated body mass index (BMI), ERBB4 and NRG4 levels decreased, while ACACA levels increased. A strong negative correlation was observed between NRG4 and ACACA levels. No deregulation of the analyzed transcripts was detected in NAFLD. The study demonstrates a decrease in ERBB4 and NRG4 mRNA expression in the livers of subjects with high BMI but not in those with NAFLD. The correlation of the studied transcripts with major lipogenesis genes was assessed, and on this basis a putative scheme for NRG4-mediated suppression of hepatic de novo lipogenesis was hypothesised, offering new research vectors in this field.

Dietary Solid-state-fermentation product of Bacillus velezensis T23 alleviate hepatic steatosis, oxidative stress, gut barrier damage, and microbiota dysbiosis in juvenile genetically improved farmed tilapia (GIFT, Oreochromis niloticus)

The application of commensal probiotic bacteria is one of the preferable green feed additives for antibiotic substitution in aquaculture, while the application methods and detailed action mechanisms of commensal bacteria isolated from aquatic animals are not consistent with normal mammalian-derived probiotics. The purpose of this study was to evaluate the effects of solid-state fermentation product of autochthonous Bacillus velezensis T23 on improving hepatic steatosis, liver antioxidation capacity, gut injury and gut microbiota profile of genetically improved farmed tilapia (GIFT, Oreochromis niloticus). The T23 probiotic was added to the basal diet at a level of 0.00, 0.05, 0.1, 0.2 and 0.3 g/kg to develop five experimental diets, respectively. After 4 weeks of the feeding trial, the results showed that T23 supplementation notably reduced the hepatocytes vacuolization and the content of liver TAGs by downregulated the mRNA expression of the lipogenesis gene (fas), while upregulated the mRNA expression of lipid degradation genes (cpt1 and pparα) (p < 0.05). Compared with the control, the 0.3T23 group showed significantly upregulated expression levels of anti-inflammatory cytokine genes (tgf-β and il-10) in the liver of the fish (p < 0.05). Besides, the activities of antioxidase SOD and CAT were significantly upregulated in T23 treatment groups, compared with the control (p < 0.05). Fish groups fed with 0.2 g/kg and 0.3 g/kg T23 supplemented diet also exhibited significantly lower intestinal injury and intestinal inflammation via upregulating the expression of tight junction protein gene claudin, anti-inflammatory factor gene il-10 (p < 0.05). However, markedly downregulation of the mRNA level of pro-inflammatory cytokine il-1β (p < 0.05) was observed in 0.05 and 0.3T23 groups, compared with the control. 16S rRNA sequencing analysis data on gut microbiota indicated that supplementation of T23 at lower levels (0.05, 0.1 and 0.2) resulted in a remarkable elevation of the abundance of phylum Firmicutes and reduced the abundance of Proteobacteria, and the ratio of (Firmicutes +Bacteroidota +Fusobacteria) /Proteobacteria. On the contrary, feeding with 0.3T23 negatively affects the gut microbiota diversity and structure of tilapia. Therefore, a 0.2 g/kg dose is suggested to supplement the diet of Nile tilapia to improve liver health and modulate the gut microbiota profile of the fish positively. Overall, these findings provide a shred of beneficial evidence of the application of B. velezensis T23 as a green feed additive to improve the productivity and profitability of tilapia farming.

Circadian Clock Disruption and Growth of Kidney Cysts in Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in the PKD1 and PKD2 genes, and often progresses to kidney failure. ADPKD progression is not uniform among patients, suggesting that factors secondary to the PKD1/2 gene mutation could regulate the rate of disease progression. Here we tested the effect of circadian clock disruption on ADPKD progression. Circadian rhythms are regulated by cell-autonomous circadian clocks composed of clock proteins. BMAL1 is a core constituent of the circadian clock. To disrupt the circadian clock, we deleted Bmal1 gene in the renal collecting ducts of the Pkd1RC/RC (RC/RC) mouse model of ADPKD (RC/RC;Bmal1f/f;Pkhd1cre, called DKO mice), and in Pkd1 knockout mouse inner medullary collecting duct cells (Pkd1Bmal1KO mIMCD3 cells). Only male mice were used. Human nephrectomy ADPKD kidneys showed altered clock gene expression when compared to normal control human kidneys. When compared to RC/RC kidneys, DKO kidneys showed significantly altered clock gene expression, increased cyst growth, cell proliferation, apoptosis and fibrosis. DKO kidneys also showed increased lipogenesis and cholesterol synthesis-related gene expression, and increased tissue triglyceride levels compared to RC/RC kidneys. Similarly, in vitro, Pkd1Bmal1KO cells showed altered clock genes, increased lipogenesis and cholesterol synthesis-related genes, and reduced fatty-acid oxidation-related gene expression compared to Pkd1KO cells. The Pkd1Bmal1KO cells showed increased cell proliferation compared to Pkd1KO cells, which was rescued by pharmacological inhibition of lipogenesis. Renal collecting duct specific Bmal1 gene deletion disrupted the circadian clock and triggered accelerated ADPKD progression by altering lipid metabolism-related gene expression.

Comparing the obesogenic effect and regulatory mechanisms of long-term exposure to per/polyfluoroalkyl substances with different terminal groups in Caenorhabditis elegans

Per/polyfluoroalkyl substances (PFASs) are ubiquitous, bioaccumulative, and recalcitrant contaminants, posing global exposure and health risks. The effects of chemical structures on toxicities and the mechanisms of their obesogenic effects were largely unclear. This study used the model organism Caenorhabditis elegans to assess the impact of long-term exposure to different PFASs (PFNA, PFOSA, PFBS, PFHxS, 6:2 FTS, 4:2 FTS, PFOA, and PFOS) on growth and lipid metabolism and discussed the obesogenic mechanisms of selected PFASs. The growth assays indicated longer carbon-fluorine (-CF) chains and total fluorine atoms increased developmental toxicity of PFASs, while at 8 –CF chain-length, PFNA (-COOH terminal), PFOS (-SO3 terminal), and PFOSA (-SO2NH2 terminal) exhibited differential growth inhibition. With the toxicity ranking of PFNA > PFOS > PFOSA, all PFASs significantly induced total lipid accumulation and perturbed the lipid composition in C. elegans. All three PFASs significantly induced lipogenesis gene expression and partially suppressed lipolysis genes. The results suggested that the disruption of lipid metabolism of PFOSA depends on sbp-1, while PFNA and PFOS depend on nhr-49. In conclusion, long-term exposure to PFNA, PFOSA, and PFOS triggers obesogenic effects in organisms by distinct molecular mechanisms.

Lacticaseibacillus paracsei HY7207 Alleviates Hepatic Steatosis, Inflammation, and Liver Fibrosis in Mice with Non-Alcoholic Fatty Liver Disease.

Non-alcoholic fatty acid disease (NAFLD) is caused by a build-up of fat in the liver, inducing local inflammation and fibrosis. We evaluated the effects of probiotic lactic acid-generating bacteria (LAB) derived from a traditional fermented beverage in a mouse model of NAFLD. The LAB isolated from this traditional Korean beverage were screened using the human hepatic cell line HepG2, and Lactocaseibacillus paracasei HY7207 (HY7207), which was the most effective inhibitor of fat accumulation, was selected for further study. HY7207 showed stable productivity in industrial-scale culture. Whole-genome sequencing of HY7207 revealed that the genome was 2.88 Mbp long, with 46.43% GC contents and 2778 predicted protein-coding DNA sequences (CDSs). HY7207 reduced the expression of lipogenesis and hepatic apoptosis-related genes in HepG2 cells treated with palmitic acid. Furthermore, the administration of 109 CFU/kg/day of HY7207 for 8 weeks to mice fed an NAFLD-inducing diet improved their physiologic and serum biochemical parameters and ameliorated their hepatic steatosis. In addition, HY7207 reduced the hepatic expression of genes important for lipogenesis (Srebp1c, Fasn, C/ebpa, Pparg, and Acaca), inflammation (Tnf, Il1b, and Ccl2), and fibrosis (Col1a1, Tgfb1, and Timp1). Finally, HY7207 affected the expression of the apoptosis-related genes Bax (encoding Bcl2 associated X, an apoptosis regulator) and Bcl2 (encoding B-cell lymphoma protein 2) in the liver. These data suggest that HY7207 consumption ameliorates NAFLD in mice through effects on liver steatosis, inflammation, fibrosis, and hepatic apoptosis. Thus, L. paracasei HY7207 may be suitable for use as a functional food supplement for patients with NAFLD.

Salusin‑α alleviates lipid metabolism disorders via regulation of the downstream lipogenesis genes through the LKB1/AMPK pathway.

Lipid metabolism disorders are a major cause of several chronic metabolic diseases which seriously affect public health. Salusin‑α, a vasoactive peptide, has been shown to attenuate lipid metabolism disorders, although its mechanism of action has not been reported. To investigate the effects and potential mechanisms of Salusin‑α on lipid metabolism, Salusin‑α was overexpressed or knocked down using lentiviral vectors. Hepatocyte steatosis was induced by free fatty acid (FFA) after lentiviral transfection into HepG2 cells. The degree of lipid accumulation was assessed using Oil Red O staining and by measuring several biochemical indices. Subsequently, bioinformatics was used to analyze the signaling pathways that may have been involved in lipid metabolism disorders. Finally, semi‑quantitative PCR and western blotting were used to verify the involvement of the liver kinase B1 (LKB1)/AMPK pathway. Compound C, an inhibitor of AMPK, was used to confirm this mechanism's involvement further. The results showed that Salusin‑α significantly attenuated lipid accumulation, inflammation and oxidative stress. In addition, Salusin‑α increased the levels of LKB1 and AMPK, which inhibited the expression of sterol regulatory element binding protein‑1c, fatty acid synthase and acetyl‑CoA carboxylase. The addition of Compound C abrogated the Salusin‑α‑mediated regulation of AMPK on downstream signaling molecules. In summary, overexpression of Salusin‑α activated the LKB1/AMPK pathway, which in turn inhibited lipid accumulation in HepG2 cells. This provides insights into the potential mechanism underlying the mechanism by which Salusin‑α ameliorates lipid metabolism disorders while identifying a potential therapeutic target.

A high-cholesterol zebrafish diet promotes hypercholesterolemia and fasting-associated liver steatosis

Zebrafish are an ideal model organism to study lipid metabolism and to elucidate the molecular underpinnings of human lipid-associated disorders. Unlike murine models, to which various standardized high lipid diets such as a high-cholesterol diet (HCD) are available, there has yet to be a uniformly adopted zebrafish HCD protocol. In this study, we have developed an improved HCD protocol and thoroughly tested its impact on zebrafish lipid deposition and lipoprotein regulation in a dose- and time-dependent manner. The diet stability, reproducibility, and fish palatability were also validated. Fish fed HCD developed hypercholesterolemia as indicated by significantly elevated ApoB-containing lipoproteins (ApoB-LPs) and increased plasma levels of cholesterol and cholesterol esters. Feeding of the HCD to larvae for 8 days produced hepatic steatosis that became more stable and sever after 1 day of fasting and was associated with an opaque liver phenotype (dark under transmitted light). Unlike larvae, adult fish fed HCD for 14 days followed by a 3-day fast did not develop a stable fatty liver phenotype, though the fish had higher ApoB-LP levels in plasma and an upregulated lipogenesis gene fasn in adipose tissue. In conclusion, our HCD zebrafish protocol represents an effective and reliable approach for studying the temporal characteristics of the physiological and biochemical responses to high levels of dietary cholesterol and provides insights into the mechanisms that may underlie fatty liver disease.

Circadian clock disruption and growth of kidney cysts in autosomal dominant polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in the PKD1 and PKD2 genes, and often progresses to kidney failure. ADPKD progression is not uniform among patients, suggesting that factors secondary to the PKD1/2 gene mutation could regulate the rate of disease progression. Here we tested the effect of circadian clock disruption on ADPKD progression. Circadian rhythms are regulated by cell-autonomous circadian clocks composed of clock proteins. BMAL1 is a core constituent of the circadian clock. To disrupt the circadian clock, we deleted Bmal1 gene in the renal collecting ducts of the Pkd1 RC/RC (RC/RC) mouse model of ADPKD (RC/RC; Bmal1 f/f ; Pkhd1 cre , called DKO mice), and in Pkd1 knockout mouse inner medullary collecting duct cells ( Pkd1Bmal1 KO mIMCD3 cells). Only male mice were used. Human nephrectomy ADPKD kidneys and Pkd1 KO mIMCD3 cells showed reduced Bmal1 gene expression compared to normal controls. When compared to RC/RC kidneys, DKO kidneys showed significantly altered clock gene expression, increased cyst growth, cell proliferation, apoptosis and fibrosis. DKO kidneys also showed increased lipogenesis and cholesterol synthesis-related gene expression, and increased tissue triglyceride levels compared to RC/RC kidneys. Similarly, in vitro, Pkd1Bmal1 KO cells showed altered clock genes, increased lipogenesis and cholesterol synthesis-related genes, and reduced fatty-acid oxidation-related gene expression compared to Pkd1KO cells. The Pkd1Bmal1 KO cells showed increased cell proliferation compared to Pkd1KO cells, which was rescued by pharmacological inhibition of lipogenesis. Renal collecting duct specific Bmal1 gene deletion disrupts the circadian clock and triggers accelerated ADPKD progression by altering lipid metabolism-related gene expression. Lack of BMAL1, a circadian clock protein in renal collecting ducts disrupted the clock and increased cyst growth and fibrosis in an ADPKD mouse model.BMAL1 gene deletion increased cell proliferation by increasing lipogenesis in kidney cells.Thus, circadian clock disruption could be a risk factor for accelerated disease progression in patients with ADPKD.

Mung bean protein pre-fibrils are superior than the mature fibrils in stabilizing HIPEs and controlling the lipid digestion to inhibit in vivo adipose accumulation

Excessive consumption of lipids is one of the major reasons for the prevalence of obesity. Interfacial engineering of food emulsions is highly expected to control the digestion and absorption of lipids, consequently to inhibit adipose expansion. However, this strategy is restricted mainly due to the lack of effective food emulsifiers. In the present study, the mung bean protein fibrils with short worm-like morphology were demonstrated to have superior capabilities than the mature ones in stabilizing high internal phase emulsions (HIPEs) and consequently inhibiting the lipid digestion to control in vivo adipose accumulation. The short worm-like pre-fibrils showed a faster adsorption kinetics to the oil/water interface to reduce the interfacial tension to a substantially lower level compared with the mature fibrils. The HIPEs stabilized by the worm-like pre-fibrils showed a wider range of oil phase volume fractions and protein fibril concentrations, which showed the characteristic connected polygon oil droplets network microstructure due to the squeezing of oil droplets. In comparison, the HIPEs stabilized by the mature mung bean protein fibrils were unstable, undergoing ostwald ripening with the appearance of big oil droplets shortly after the preparation. Consequently, significantly less free fatty acids were released from the HIPEs stabilized by the worm-like pre-fibrils compared with the mature ones in the in vitro stimulating digestion assay. Interestingly, compared with the HIPEs emulsified by the mature amyloid-like fibrils (HIPEs-M group), long-term oral administration of mice with the HIPEs stabilized by the worm-like pre-fibrils (HIPEs-W group) resulted in significantly lower body weight and substantially inhibited adipose expansion. The genes related to lipolysis were over-expressed and the expression of the lipogenesis genes were down-regulated in adipose tissue in HIPEs-W group compared with those in HIPEs-M group. Furthermore, fecal lipid content in HIPEs-W group was higher than that in HIPEs-M group; and the expression of genes related to lipid adsorption in intestine, such as FATP4, FABP-1, PPAR-α, MTTP-1 and CPT1A was down-regulated. Therefore, restriction of lipid digestion and absorption in intestine could serve as the mechanism for the inhibition of in vivo adipose expansion caused by the HIPEs stabilized by the worm-like fibrils compared with the mature fibrils.

Prefeeding of berberine alleviates waterborne copper-induced hepatic oxidative stress, lipid deposition, and intestinal microbiota dysbiosis in yellow catfish (Pelteobagrus fulvidraco)

Copper (Cu) contamination is a common issue in aquaculture and normally leads to hepatic and intestinal damage in fish. Due to the effective lipid-lowering, antioxidative, and intestinal microbiota-maintaining properties of berberine (BBR), it has the potential to be a feed additive to diminish Cu toxicity in fish. This study aimed to determine whether berberine could alleviate hepatic and intestinal damage in yellow catfish (Pelteobagrus fulvidraco) caused by waterborne Cu2+ exposure. The fish with the same weight (2.65 ± 0.25 g) were assigned to four groups: a control group (Con) that received a control diet for nine weeks; a Cu group, a BBR100 group, and a BBR400 group that received the control diet, 100 mg/kg berberine, and 400 mg/kg berberine for eight weeks, respectively, and after that, they were exposed to 0.8 mg/L Cu2+ for an additional week. The BBR100 and BBR 400 groups had significantly higher weight gain than the Cu group, but significantly lower hepatic and serum total cholesterol and triglyceride levels, and berberine treatment significantly improved intestinal and hepatic histological damage (P < 0.05). Berberine treatment significantly increased intestinal complement 3 and complement 4 levels but distinctly regulated hepatic and intestinal antioxidant enzyme activities while significantly reducing malondialdehyde levels compared to those in the Cu group. In addition, pretreatment with berberine significantly increased the expression levels of intestinal farnesoid X receptor (fxr) and fibroblast growth factor 19, as well as hepatic fxr, and downregulated the expression of its downstream lipogenesis genes (srebp1c, fas, and pparγ). Based on 16S rDNA analysis, the abundances of some probiotic bacteria (e.g., Lactobacillus) were elevated, but the abundances of some pathogenic bacteria (e.g., Morganella) decreased in the BBR400 group. At KEGG level 3, the pathway related to “Pathogenic Escherichia coli infection” was significantly enriched in the Cu group but significantly lower enriched in the BBR100 group. These findings indicated that berberine alleviated waterborne copper-induced hepatic and intestinal damage mainly by activating the FXR pathway, reducing oxidative stress and lipid deposition, and maintaining intestinal microbiota homeostasis in yellow catfish.

Dramatic Suppression of Lipogenesis and No Increase in Beta-Oxidation Gene Expression Are among the Key Effects of Bergamot Flavonoids in Fatty Liver Disease.

Bergamot flavonoids have been shown to prevent metabolic syndrome, non-alcoholic fatty liver disease (NAFLD) and stimulate autophagy in animal models and patients. To investigate further the mechanism of polyphenol-dependent effects, we performed a RT2-PCR array analysis on 168 metabolism, transport and autophagy-related genes expressed in rat livers exposed for 14 weeks to different diets: standard, cafeteria (CAF) and CAF diet supplemented with 50 mg/kg of bergamot polyphenol fraction (BPF). CAF diet caused a strong upregulation of gluconeogenesis pathway (Gck, Pck2) and a moderate (>1.7 fold) induction of genes regulating lipogenesis (Srebf1, Pparg, Xbp1), lipid and cholesterol transport or lipolysis (Fabp3, Apoa1, Lpl) and inflammation (Il6, Il10, Tnf). However, only one β-oxidation gene (Cpt1a) and a few autophagy genes were differentially expressed in CAF rats compared to controls. While most of these transcripts were significantly modulated by BPF, we observed a particularly potent effect on lipogenesis genes, like Acly, Acaca and Fasn, which were suppressed far below the mRNA levels of control livers as confirmed by alternative primers-based RT2-PCR analysis and western blotting. These effects were accompanied by downregulation of pro-inflammatory cytokines (Il6, Tnfa, and Il10) and diabetes-related genes. Few autophagy (Map1Lc3a, Dapk) and no β-oxidation gene expression changes were observed compared to CAF group. In conclusion, chronic BPF supplementation efficiently prevents NAFLD by modulating hepatic energy metabolism and inflammation gene expression programs, with no effect on β-oxidation, but profound suppression of de novo lipogenesis.

Metabolic and microbial mechanisms related to the effects of dietary wheat levels on intramuscular fat content in finishing pigs

The current study aimed to investigate the metabolic and microbial mechanisms behind the effects of dietary wheat levels on intramuscular fat (IMF) content in the psoas major muscle (PM) of finishing pigs. Thirty-six barrows were arbitrarily assigned to two groups and fed with diets containing 25% or 55% wheat. Enhancing dietary wheat levels led to low energy states, resulting in reduced IMF content. This coincided with reduced serum glucose and low-density lipoprotein cholesterol levels. The AMP-activated protein kinase α2/sirtuin 1/peroxisome proliferator-activated receptor-γ coactivator 1α pathway may be activated by high-wheat diets, causing downregulation of adipogenesis and lipogenesis genes, and upregulation of lipolysis and gluconeogenesis genes. High-wheat diets decreased relative abundance of Lactobacillus and Coprococcus, whereas increased SMB53 proportion, subsequently decreasing colonic propionate content. Microbial glycolysis/gluconeogenesis, d-glutamine and D-glutamate metabolism, flagellar assembly, and caprolactam degradation were linked to IMF content. Metabolomic analysis indicated that enhancing dietary wheat levels promoted the protein digestion and absorption and affected amino acids and lipid metabolism. Enhancing dietary wheat levels reduced serum glucose and colonic propionate content, coupled with strengthened amino acid metabolism, contributing to the low energy states. Furthermore, alterations in microbial composition and propionate resulted from high-wheat diets were associated with primary bile acid biosynthesis, arachidonic acid metabolism, steroid hormone biosynthesis, and biosynthesis of unsaturated fatty acids, as well as IMF content. Colonic microbiota played a role in reducing IMF content through modulating the propionate-mediated peroxisome proliferators-activated receptor signaling pathway. In conclusion, body energy and gut microbiota balance collectively influenced lipid metabolism.

Sitagliptin alleviates renal steatosis and endoplasmic reticulum stress in high fat diet-induced obese rats by targeting SREBP-1/CD36 signaling pathway

High fat diet (HFD) consumption can cause dysregulation of glucose and lipid metabolism, coupled with increased ectopic lipid deposition in renal tissue leading to steatosis and dysfunction. Sitagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor clinically used for type II diabetes therapy; however its effect on renal steatosis in obese state is still uncertain. Herein, obesity was induced by feeding male Wistar rats HFD for 18 weeks, thereafter received either drug vehicle, or sitagliptin (10 mg/kg, PO) along with HFD for further 6 weeks and compared with age-matched rats receiving normal chow diet (NCD). After 24 weeks, serum and kidneys were collected for histological and biochemical assessments. Compared to NCD-fed group, HFD-fed rats displayed marked weight gain, increased fat mass, insulin resistance, dyslipidemia, impaired kidney functions and renal histological alterations. Sitagliptin effectively ameliorated obesity and related metabolic perturbations and improved kidney architecture and function. There were increased levels of triglycerides and cluster of differentiation 36 (CD36) in kidneys of obese rats, that were lowered by sitagliptin therapy. Sitagliptin significantly repressed the expression of lipogenesis genes, while up-regulated genes involved in mitochondrial biogenesis and fatty acid oxidation in kidneys of HFD-fed rats. Sitagliptin was found to induce down-regulation of endoplasmic reticulum (ER) stress and apoptotic markers in kidneys of obese rats. These findings together may emphasize a novel concept that sitagliptin can be an effective therapeutic approach for halting obesity-related renal steatosis and CKD.

Intermittent hypoxia increases lipid insulin resistance in healthy humans: A randomized crossover trial.

Sympathetic overactivity caused by chronic intermittent hypoxia is a hallmark of obstructive sleep apnea. A high sympathetic tone elicits increases in plasma free fatty acid and insulin. Our objective was to assess the impact of 14 nights of chronic intermittent hypoxia exposure on sympathetic activity, glucose control, lipid profile and subcutaneous fat tissue remodelling in non-obese healthy humans. In this prospective, double-blinded crossover study, 12 healthy subjects were randomized, among them only nine underwent the two phases of exposures of 14 nights chronic intermittent hypoxia versus air. Sympathetic activity was measured by peroneal microneurography (muscle sympathetic nerve activity) before and after each exposure. Fasting glucose, insulin, C-peptide and free fatty acid were assessed at rest and during a multisampling oral glucose tolerance test. We assessed histological remodelling, adrenergic receptors, lipolysis and lipogenesis genes expression and functional changes of the adipose tissue. Two weeks of exposure of chronic intermittent hypoxia versus ambient air significantly increased sympathetic activity (p = 0.04). Muscle sympathetic nerve activity increased from 24.5 [18.9; 26.8] before to 21.7 [13.8; 25.7] after ambient air exposure, and from 20.6 [17.4; 23.9] before to 28.0 [24.4; 31.5] bursts per min after exposure to chronic intermittent hypoxia. After chronic intermittent hypoxia, post-oral glucose tolerance test circulating free fatty acid area under the curve increased (p = 0.05) and free fatty acid sensitivity to insulin decreased (p = 0.028). In adipocyte tissue, intermittent hypoxia increased expression of lipolysis genes (adipocyte triglyceride lipase and hormone-sensitive lipase) and lipogenesis genes (fatty acid synthase; p < 0.05). In this unique experimental setting in healthy humans, chronic intermittent hypoxia induced high sympathetic tone, lipolysis and decreased free fatty acid sensitivity to insulin. This might participate in the trajectory to systemic insulin resistance and diabetes for patients with obstructive sleep apnea.

Dietary betulinic acid alleviates high carbohydrate diet-induced hepatic de novo lipogenesis through AMPK signaling and improves liver health in channel catfish (Ictalurus punctatus)

A high carbohydrate diet (HCD) induced excessive hepatic de novo lipogenesis, which caused metabolic disorder and impaired the health of fish species. Betulinic acid (BA) has been applied to ameliorate fatty liver and anti-inflammatory in mammals. Here, we investigated the effects of dietary BA supplementation on HCD-induced hepatic de novo lipogenesis and liver health in channel catfish (Ictalurus punctatus). The catfish were fed with three diets: NCD (18 % carbohydrate), HCD (36 % carbohydrate), HCD+BA (36 % carbohydrate with 150 mg/kg BA). After an 8-week feeding trial, we found that dietary BA decreased hepatosomatic index (HSI) and condition factor (CF) without affecting the growth of channel catfish fed HCD. Dietary BA significantly reduced the HCD-induced excessive lipid accumulation (oil red O area, TG content, and de novo lipogenesis gene expression, P < 0.05). Moreover, we found that dietary BA prevented hepatic lipid accumulation via activating phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and inhibiting sterol regulatory element-binding protein 1 (SREBP1) (P < 0.05) in liver of channel catfish fed HCD. Besides, we also found that dietary BA significantly prevented HCD-induced liver damage, as confirmed by liver H&E staining, reduced inflammation biomarkers (ALT, AST, hydroxyproline, α-sma and tgf-1β), downregulated expression of ER stress-related genes (eif2a, bip, atf4, xbp1) (P < 0.05). Overall, the present study indicated that dietary BA inclusion attenuated hepatic de novo lipogenesis, improved liver inflammation and reduced ER stress in channel catfish fed HCD.

Aging impairs cold-induced beige adipogenesis and adipocyte metabolic reprogramming.

The energy-burning capability of beige adipose tissue is a potential therapeutic tool for reducing obesity and metabolic disease, but this capacity is decreased by aging. Here, we evaluate the impact of aging on the profile and activity of adipocyte stem and progenitor cells (ASPCs) and adipocytes during the beiging process in mice. We found that aging increases the expression of Cd9 and other fibro-inflammatory genes in fibroblastic ASPCs and blocks their differentiation into beige adipocytes. Fibroblastic ASPC populations from young and aged mice were equally competent for beige differentiation in vitro, suggesting that environmental factors suppress adipogenesis in vivo. Examination of adipocytes by single nucleus RNA-sequencing identified compositional and transcriptional differences in adipocyte populations with aging and cold exposure. Notably, cold exposure induced an adipocyte population expressing high levels of de novo lipogenesis (DNL) genes, and this response was severely blunted in aged animals. We further identified Npr3, which encodes the natriuretic peptide clearance receptor, as a marker gene for a subset of white adipocytes and an aging-upregulated gene in adipocytes. In summary, this study indicates that aging blocks beige adipogenesis and dysregulates adipocyte responses to cold exposure and provides a resource for identifying cold and aging-regulated pathways in adipose tissue.

Tanycytes release glucose using the glucose-6-phosphatase system during hypoglycemia to control hypothalamic energy balance

ObjectiveThe liver releases glucose into the blood using the glucose-6-phosphatase (G6Pase) system, a multiprotein complex located in the endoplasmic reticulum (ER). Here, we show for the first time that the G6Pase system is also expressed in hypothalamic tanycytes, and it is required to regulate energy balance. MethodsUsing automatized qRT-PCR and immunohistochemical analyses, we evaluated the expression of the G6Pase system. Fluorescent glucose analogue (2-NBDG) uptake was evaluated by 4D live-cell microscopy. Glucose release was tested using a glucose detection kit and high-content live-cell analysis instrument, Incucyte s3. In vivo G6pt knockdown in tanycytes was performed by AAV1-shG6PT-mCherry intracerebroventricular injection. Body weight gain, adipose tissue weight, food intake, glucose metabolism, c-Fos, and neuropeptide expression were evaluated at 4 weeks post-transduction. ResultsTanycytes sequester glucose-6-phosphate (G6P) into the ER through the G6Pase system and release glucose in hypoglycaemia via facilitative glucose transporters (GLUTs). Strikingly, in vivo tanycytic G6pt knockdown has a powerful peripheral anabolic effect observed through decreased body weight, white adipose tissue (WAT) tissue mass, and strong downregulation of lipogenesis genes. Selective deletion of G6pt in tanycytes also decreases food intake, c-Fos expression in the arcuate nucleus (ARC), and Npy mRNA expression in fasted mice. ConclusionsThe tanycyte-associated G6Pase system is a central mechanism involved in controlling metabolism and energy balance.