scholarly journals Tribbles-1: a novel regulator of hepatic lipid metabolism in humans

2015 ◽  
Vol 43 (5) ◽  
pp. 1079-1084 ◽  
Author(s):  
Robert C. Bauer ◽  
Batuhan O. Yenilmez ◽  
Daniel J. Rader
Keyword(s):  
Lipid Metabolism ◽  
Plasma Lipids ◽  
Association Studies ◽  
Plasma Lipid ◽  
Genome Wide Association Studies ◽  
Dependent Manner ◽  
Hepatic Lipogenesis ◽  
Hepatic Lipid Metabolism ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid

The protein tribbles-1, encoded by the gene TRIB1, is increasingly recognized as a major regulator of multiple cellular and physiological processes in humans. Recent human genetic studies, as well as molecular biological approaches, have implicated this intriguing protein in the aetiology of multiple human diseases, including myeloid leukaemia, Crohn's disease, non-alcoholic fatty liver disease (NAFLD), dyslipidaemia and coronary artery disease (CAD). Genome-wide association studies (GWAS) have repeatedly identified variants at the genomic TRIB1 locus as being significantly associated with multiple plasma lipid traits and cardiovascular disease (CVD) in humans. The involvement of TRIB1 in hepatic lipid metabolism has been validated through viral-mediated hepatic overexpression of the gene in mice; increasing levels of TRIB1 decreased plasma lipids in a dose-dependent manner. Additional studies have implicated TRIB1 in the regulation of hepatic lipogenesis and NAFLD. The exact mechanisms of TRIB1 regulation of both plasma lipids and hepatic lipogenesis remain undetermined, although multiple signalling pathways and transcription factors have been implicated in tribbles-1 function. Recent reports have been aimed at developing TRIB1-based lipid therapeutics. In summary, tribbles-1 is an important modulator of human energy metabolism and metabolic syndromes and worthy of future studies aimed at investigating its potential as a therapeutic target.

scholarly journals Perturbation of TM6SF2 Expression Alters Lipid Metabolism in a Human Liver Cell Line

2021 ◽  
Vol 22 (18) ◽  
pp. 9758
Author(s):  
Asmita Pant ◽  
Yue Chen ◽  
Annapurna Kuppa ◽  
Xiaomeng Du ◽  
Brian D. Halligan ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
Fluorescent Imaging ◽  
Genome Wide Association Studies ◽  
Loss Of Function ◽  
Wild Type ◽  
Hepatic Lipid Metabolism ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Human Liver Cell

Non-alcoholic fatty liver disease (NAFLD) is caused by excess lipid accumulation in hepatocytes. Genome-wide association studies have identified a strong association of NAFLD with non-synonymous E167K amino acid mutation in the transmembrane 6 superfamily member 2 (TM6SF2) protein. The E167K mutation reduces TM6SF2 stability, and its carriers display increased hepatic lipids and lower serum triglycerides. However, the effects of TM6SF2 on hepatic lipid metabolism are not completely understood. We overexpressed wild-type or E167K variant of TM6SF2 or knocked down TM6SF2 expression in lipid-treated Huh-7 cells and used untargeted lipidomic analysis, RNAseq transcriptome analysis, and fluorescent imaging to determine changes in hepatic lipid metabolism. Both TM6SF2 knockdown and E167K overexpression increased hepatic lipid accumulation, while wild-type overexpression decreased acylglyceride levels. We also observed lipid chain remodeling for acylglycerides by TM6SF2 knockdown, leading to a relative increase in species with shorter, more saturated side chains. RNA-sequencing revealed differential expression of several lipid metabolizing genes, including genes belonging to AKR1 family and lipases, primarily in cells with TM6SF2 knockdown. Taken together, our data show that overexpression of TM6SF2 gene or its loss-of-function changes hepatic lipid species composition and expression of lipid metabolizing genes. Additionally, our data further confirms a loss-of-function effect for the E167K variant.

Abstract 75: Somatic Overexpression and Knockdown in Mice to Identify Causal Genes Underlying 26 Lipid-associated Loci

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Evanthia Pashos ◽  
Ioannis M Stylianou ◽  
Dawn Marchadier ◽  
Antonino Picataggi ◽  
Valeska S Redon ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Plasma Lipids ◽  
Association Studies ◽  
Plasma Lipid ◽  
Genome Wide Association Studies ◽  
Humanized Mouse Model ◽  
Human Apolipoprotein ◽  
Virus Serotype ◽  
Causal Genes

Genome-wide association studies (GWAS) have identified 95 loci in the human genome that harbor common variants associated with plasma lipid traits. Of the 95 loci, 17 harbor genes known to cause monogenic lipid disorders and collectively a third of them contain genes with characterized roles in lipid metabolism. Therefore in the majority of loci the causal genes are unknown. We selected 32 genes, not previously implicated in lipid metabolism and representing a total of 26 loci, to test for their ability to modify plasma lipid concentrations upon somatic overexpression in vivo. We utilized adeno-associated virus serotype 8 (AAV8) to overexpress the selected genes specifically in the livers of both C57BL/6 mice and in an appropriate humanized mouse model (either mice expressing human apolipoprotein A-I for HDL loci or Apobec1-knockout, Ldlr haploinsufficient mice expressing human apolipoprotein B-100 for triglyceride and LDL loci). Approximately half of the genes tested reproducibly affected plasma lipids. For 13 of the interrogated loci the lipid-associated variants also correlated with expression variations of the respective genes in liver (liver expression quantitative trait loci-eQTLs). We demonstrate a causal role for 7 of these 13 genes. The overexpression of these 7 genes not only affected the predicted lipid class, but additionally exerted its effect in the predicted direction in 6 of 7 cases (Tmem57, Slc39a8, Ppp1r3b, Vkorc1, Tbkbp1 and Ube2l3). Additionally for a subset of the examined genes we proceeded to develop small interfering RNA (siRNA) nanoparticles that were particularly targeted to the liver. We were able to obtain robust knockdown for a significant number of genes and, in several cases, observe reciprocal effects on plasma lipids from our overexpression and knockdown studies. This work has identified several novel lipid regulators, whose further investigation can uncover novel mechanisms and pathways controlling plasma lipids.

scholarly journals ANGPTL3 Variants Associate with Lower Levels of Irisin and C-Peptide in a Cohort of Arab Individuals

2021 ◽  
Author(s):  
Muath Alanbaei ◽  
Mohamed Abu-Farha ◽  
Prashantha Hebbar ◽  
Motasem Melhem ◽  
Betty S Chandy ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Association Studies ◽  
Plasma Lipid ◽  
Genome Wide Association Studies ◽  
Metabolic Markers ◽  
P Values ◽  
C Peptide ◽  
Potential Link ◽  
The Impact

ANGPTL3 is an important regulator of lipid metabolism. Its inhibition in people with hypercholesteremia reduces plasma lipid levels dramatically. Genome-wide association studies have associated ANGPTL3 variants with lipid traits. Irisin, an exercise modulated protein, has been associated with lipid metabolism. Intracellular accumulation of lipids impairs insulin action and contributes to metabolic disorders. In this study, we evaluate the impact of ANGPTL3 variants on levels of irisin and markers associated with lipid metabolism and insulin resistance. ANGPTL3 rs1748197 and rs12130333 variants were genotyped in a cohort of 278 Arab individuals from Kuwait. Levels of irisin and other metabolic markers were measured by ELISA. Significance of association signals was assessed using Bonferroni-corrected P-values and empirical P-values. The study variants were significantly associated with low levels of c-peptide and irisin. Levels of c-peptide and irisin were mediated by interaction between carrier genotypes (GA+AA) at rs1748197 and measures of IL13 and TG, respectively. While levels of c-peptide and IL13 were directly correlated in individuals with reference genotype, they were inversely correlated in individuals with carrier genotype. Irisin correlated positively with TG which is strong in individuals with carrier genotypes. These observations illustrate ANGPTL3 as a potential link connecting lipid metabolism, insulin resistance and cardioprotection.

scholarly journals Effects of Chitosan Oligosaccharide on Plasma and Hepatic Lipid Metabolism and Liver Histomorphology in Normal Sprague-Dawley Rats

Marine Drugs ◽  
2020 ◽  
Vol 18 (8) ◽  
pp. 408 ◽  
Author(s):  
Shing-Hwa Liu ◽  
Rui-Yi Chen ◽  
Meng-Tsan Chiang
Keyword(s):  
Lipid Metabolism ◽  
Normal Control ◽  
Plasma Lipids ◽  
Control Diet ◽  
The Body ◽  
Chitosan Oligosaccharide ◽  
Sprague Dawley ◽  
Hepatic Lipid Metabolism ◽  
Hepatic Lipid ◽  
Sprague Dawley Rats

Chitosan oligosaccharide is known to ameliorate hypercholesterolemia and diabetes. However, some studies found that chitosan oligosaccharide might induce mild to moderate hepatic damage in high-fat (HF) diet-induced obese rats or diabetic rats. Chitosan oligosaccharide can be as a dietary supplement, functional food, or drug. Its possible toxic effects to normal subjects need to be clarified. This study is designed to investigate the effects of chitosan oligosaccharide on plasma and hepatic lipid metabolism and liver histomorphology in normal Sprague-Dawley rats. Diets supplemented with 5% chitosan oligosaccharide have been found to induce liver damage in HF diet-fed rats. We therefore selected 5% chitosan oligosaccharide as an experimental object. Rats were divided into: a normal control diet group and a normal control diet +5% chitosan oligosaccharide group. The experimental period was 12 weeks. The results showed that supplementation of 5% chitosan oligosaccharide did not significantly change the body weight, food intake, liver/adipose tissue weights, plasma lipids, hepatic lipids, plasma levels of AST, ALT, and TNF-α/IL-6, hepatic lipid peroxidation and anti-oxidative enzyme activities, fecal lipids, and liver histomorphology in normal rats. These findings suggest that supplementation of 5% chitosan oligosaccharide for 12 weeks may not induce lipid metabolism disorder and liver toxicity in normal rats.

Effect of specific amino acids on hepatic lipid metabolism in fructose-induced non-alcoholic fatty liver disease

2016 ◽  
Vol 35 (1) ◽  
pp. 175-182 ◽  
Author(s):  
Prasanthi Jegatheesan ◽  
Stéphanie Beutheu ◽  
Gabrielle Ventura ◽  
Gilles Sarfati ◽  
Esther Nubret ◽  
...  
Keyword(s):  
Amino Acids ◽  
Lipid Metabolism ◽  
Liver Disease ◽  
Fatty Liver ◽  
Fatty Liver Disease ◽  
Hepatic Lipid Metabolism ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Alcoholic Fatty Liver Disease

scholarly journals ANGPTL3 Variants Associate with Lower Levels of Irisin and C-Peptide in a Cohort of Arab Individuals

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 755
Author(s):  
Muath Alanbaei ◽  
Mohamed Abu-Farha ◽  
Prashantha Hebbar ◽  
Motasem Melhem ◽  
Betty S. Chandy ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Lipid Metabolism ◽  
Association Studies ◽  
Plasma Lipid ◽  
Genome Wide Association Studies ◽  
Metabolic Markers ◽  
P Values ◽  
C Peptide ◽  
Potential Link ◽  
The Impact

ANGPTL3 is an important regulator of lipid metabolism. Its inhibition in people with hypercholesteremia reduces plasma lipid levels dramatically. Genome-wide association studies have associated ANGPTL3 variants with lipid traits. Irisin, an exercise-modulated protein, has been associated with lipid metabolism. Intracellular accumulation of lipids impairs insulin action and contributes to metabolic disorders. In this study, we evaluate the impact of ANGPTL3 variants on levels of irisin and markers associated with lipid metabolism and insulin resistance. ANGPTL3 rs1748197 and rs12130333 variants were genotyped in a cohort of 278 Arab individuals from Kuwait. Levels of irisin and other metabolic markers were measured by ELISA. Significance of association signals was assessed using Bonferroni-corrected p-values and empirical p-values. The study variants were significantly associated with low levels of c-peptide and irisin. Levels of c-peptide and irisin were mediated by interaction between carrier genotypes (GA + AA) at rs1748197 and measures of IL13 and TG, respectively. While levels of c-peptide and IL13 were directly correlated in individuals with the reference genotype, they were inversely correlated in individuals with the carrier genotype. Irisin correlated positively with TG and was strong in individuals with carrier genotypes. These observations illustrate ANGPTL3 as a potential link connecting lipid metabolism, insulin resistance and cardioprotection.

scholarly journals Hepatic MIR20B promotes nonalcoholic fatty liver disease by suppressing PPARA

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Yo Han Lee ◽  
Hyun-Jun Jang ◽  
Sounkou Kim ◽  
Sun Sil Choi ◽  
Keon Woo Khim ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Liver Disease ◽  
Network Analysis ◽  
Fatty Liver ◽  
Lipid Accumulation ◽  
Fatty Liver Disease ◽  
Synergic Effect ◽  
Hepatic Lipid Metabolism ◽  
Alcoholic Fatty Liver ◽  
Hepatic Lipid

Background:Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and imbalances in lipid metabolism in the liver. Although nuclear receptors (NRs) play a crucial role in hepatic lipid metabolism, the underlying mechanisms of NR regulation in NAFLD remain largely unclear. Methods:Using network analysis and RNA-seq to determine the correlation between NRs and microRNA in human NAFLD patients, we revealed that MIR20B specifically targets PPARA. MIR20B mimic and anti-MIR20B were administered to human HepG2 and Huh-7 cells and mouse primary hepatocytes as well as high fat diet (HFD)- or methionine-deficient diet (MCD)-fed mice to verify the specific function of MIR20B in NAFLD. We tested the inhibition of the therapeutic effect of a PPARα agonist, fenofibrate, by Mir20b and the synergic effect of combination of fenofibrate with anti-Mir20b in NAFLD mouse model. Results:We revealed that MIR20B specifically targets PPARA through miRNA regulatory network analysis of nuclear receptor genes in NAFLD. The expression of MIR20B was upregulated in free fatty acid (FA)-treated hepatocytes and the livers of both obesity-induced mice and NAFLD patients. Overexpression of MIR20B significantly increased hepatic lipid accumulation and triglyceride levels. Furthermore, MIR20B significantly reduced FA oxidation and mitochondrial biogenesis by targeting PPARA. In Mir20b-introduced mice, the effect of fenofibrate to ameliorate hepatic steatosis was significantly suppressed. Finally, inhibition of Mir20b significantly increased FA oxidation and uptake, resulting in improved insulin sensitivity and a decrease in NAFLD progression. Moreover, combination of fenofibrate and anti-Mir20b exhibited the synergic effect on improvement of NAFLD in MCD-fed mice. Conclusions:Taken together, our results demonstrate that the novel MIR20B targets PPARA, plays a significant role in hepatic lipid metabolism, and present an opportunity for the development of novel therapeutics for NAFLD. Funding:This research was funded by Korea Mouse Phenotyping Project (2016M3A9D5A01952411), the National Research Foundation of Korea (NRF) grant funded by the Korea government (2020R1F1A1061267, 2018R1A5A1024340, NRF-2021R1I1A2041463, 2020R1I1A1A01074940), and the Future-leading Project Research Fund (1.210034.01) of UNIST.

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