Systems genetics of liver injury in ABCB4 deficiency: identification of genetic modifiers involved in hepatic cholesterol homeostasis

2018 ◽  
Vol 56 (01) ◽  
pp. E2-E89
Author(s):  
R Hall ◽  
M Krawczyk ◽  
K Hochrath ◽  
M Milkiewicz ◽  
P Milkiewicz ◽  
...  
Keyword(s):  
Liver Injury ◽  
Cholesterol Homeostasis ◽  
Systems Genetics ◽  
Genetic Modifiers ◽  
Hepatic Cholesterol

scholarly journals Characterizing the Role of HMG-CoA Reductase in Aryl Hydrocarbon Receptor-Mediated Liver Injury in C57BL/6 Mice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Peter Dornbos ◽  
Amanda Jurgelewicz ◽  
Kelly A. Fader ◽  
Kurt Williams ◽  
Timothy R. Zacharewski ◽  
...  
Keyword(s):  
Liver Injury ◽  
Aryl Hydrocarbon Receptor ◽  
Cholesterol Biosynthesis ◽  
Competitive Inhibitor ◽  
Cholesterol Homeostasis ◽  
Hepatic Glycogen ◽  
Alcoholic Fatty Liver ◽  
Female Mice ◽  
Aryl Hydrocarbon ◽  
The Impact

Abstract The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor. The prototypical ligand of the AHR is an environmental contaminant called 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD exposure is associated with many adverse health outcomes in humans including non-alcoholic fatty liver disease (NAFLD). Previous studies suggest that AHR ligands alter cholesterol homeostasis in mice through repression of genes involved in cholesterol biosynthesis, such as Hmgcr, which encodes the rate-limiting enzyme of cholesterol biosynthesis called 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCR). In this study, we sought to characterize the impact of HMGCR repression in TCDD-induced liver injury. C57BL/6 mice were exposed to TCDD in the presence or absence of simvastatin, a competitive inhibitor of HMGCR. Simvastatin exposure decreased TCDD-induced hepatic lipid accumulation in both sexes, but was most prominent in females. Simvastatin and TCDD (S + T) co-treatment increased hepatic AHR-battery gene expression and liver injury in male, but not female, mice. In addition, the S + T co-treatment led to an increase in hepatic glycogen content that coincides with heavier liver in female mice. Results from this study suggest that statins, which are amongst the most prescribed pharmaceuticals, may protect from AHR-mediated steatosis, but alter glycogen metabolism and increase the risk of TCDD-elicited liver damage in a sex-specific manner.

scholarly journals Energy determinants GAPDH and NDPK act as genetic modifiers for hepatocyte inclusion formation

2011 ◽  
Vol 195 (2) ◽  
pp. 217-229 ◽  
Author(s):  
Natasha T. Snider ◽  
Sujith V.W. Weerasinghe ◽  
Amika Singla ◽  
Jessica M. Leonard ◽  
Shinichiro Hanada ◽  
...  
Keyword(s):  
Liver Injury ◽  
Human Liver ◽  
Nuclear Translocation ◽  
Nucleoside Diphosphate Kinase ◽  
Isolated Hepatocytes ◽  
Dependent Manner ◽  
Genetic Modifiers ◽  
C3h Mice ◽  
Normal Human ◽  
Human Livers

Genetic factors impact liver injury susceptibility and disease progression. Prominent histological features of some chronic human liver diseases are hepatocyte ballooning and Mallory-Denk bodies. In mice, these features are induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) in a strain-dependent manner, with the C57BL and C3H strains showing high and low susceptibility, respectively. To identify modifiers of DDC-induced liver injury, we compared C57BL and C3H mice using proteomic, biochemical, and cell biological tools. DDC elevated reactive oxygen species (ROS) and oxidative stress enzymes preferentially in C57BL livers and isolated hepatocytes. C57BL livers and hepatocytes also manifested significant down-regulation, aggregation, and nuclear translocation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH). GAPDH knockdown depleted bioenergetic and antioxidant enzymes and elevated hepatocyte ROS, whereas GAPDH overexpression decreased hepatocyte ROS. On the other hand, C3H livers had higher expression and activity of the energy-generating nucleoside-diphosphate kinase (NDPK), and knockdown of hepatocyte NDPK augmented DDC-induced ROS formation. Consistent with these findings, cirrhotic, but not normal, human livers contained GAPDH aggregates and NDPK complexes. We propose that GAPDH and NDPK are genetic modifiers of murine DDC-induced liver injury and potentially human liver disease.

scholarly journals Mechanisms of cholesterol-lowering effects of dietary insoluble fibres: relationships with intestinal and hepatic cholesterol parameters

2005 ◽  
Vol 94 (3) ◽  
pp. 331-337 ◽  
Author(s):  
Ariëtte M. van Bennekum ◽  
David V. Nguyen ◽  
Georg Schulthess ◽  
Helmut Hauser ◽  
Michael C. Phillips
Keyword(s):  
Bile Acid ◽  
Food Intake ◽  
Serum Cholesterol ◽  
Cholesterol Absorption ◽  
Cholesterol Homeostasis ◽  
Hepatic Cholesterol ◽  
Intestinal Cholesterol Absorption ◽  
Cholesterol Lowering ◽  
Dietary Fibres ◽  
Bile Acid Binding

Fibres with a range of abilities to perturb cholesterol homeostasis were used to investigate how the serum cholesterol-lowering effects of insoluble dietary fibres are related to parameters of intestinal cholesterol absorption and hepatic cholesterol homeostasis in mice. Cholestyramine, chitosan and cellulose were used as examples of fibres with high, intermediate and low bile acid-binding capacities, respectively. The serum cholesterol levels in a control group of mice fed a high fat/high cholesterol (HFHC) diet for 3 weeks increased about 2-fold to 4·3 mm and inclusion of any of these fibres at 7·5 % of the diet prevented this increase from occurring. In addition, the amount of cholesterol accumulated in hepatic stores due to the HFHC diet was reduced by treatment with these fibres. The three kinds of fibres showed similar hypocholesterolaemic activity; however, cholesterol depletion of liver tissue was greatest with cholestyramine. The mechanisms underlying the cholesterol-lowering effect of cholestyramine were (1) decreased cholesterol (food) intake, (2) decreased cholesterol absorption efficiency, and (3) increased faecal bile acid and cholesterol excretion. The latter effects can be attributed to the high bile acid-binding capacity of cholestyramine. In contrast, incorporation of chitosan or cellulose in the diet reduced cholesterol (food) intake, but did not affect either intestinal cholesterol absorption or faecal sterol output. The present study provides strong evidence that above all satiation and satiety effects underlie the cholesterol-lowering properties of insoluble dietary fibres with moderate or low bile acid-binding capabilities.

scholarly journals Murine deficiency of peroxisomal L-bifunctional protein (EHHADH) causes medium-chain 3-hydroxydicarboxylic aciduria and perturbs hepatic cholesterol homeostasis

2021 ◽  
Author(s):  
Pablo Ranea-Robles ◽  
Sara Violante ◽  
Carmen Argmann ◽  
Tetyana Dodatko ◽  
Dipankar Bhattacharya ◽  
...  
Keyword(s):  
Essential Role ◽  
Cholesterol Biosynthesis ◽  
Cholesterol Homeostasis ◽  
Acid Oxidation ◽  
Hepatic Cholesterol ◽  
Mitochondrial Fatty Acid Oxidation ◽  
Bifunctional Protein ◽  
Medium Chain ◽  
Mitochondrial Fatty Acid

AbstractPeroxisomes play an essential role in the β-oxidation of dicarboxylic acids (DCAs), which are metabolites formed upon ω-oxidation of fatty acids. Genetic evidence linking transporters and enzymes to specific DCA β-oxidation steps is generally lacking. Moreover, the physiological functions of DCA metabolism remain largely unknown. In this study, we aimed to characterize the DCA β-oxidation pathway in human cells, and to evaluate the biological role of DCA metabolism using mice deficient in the peroxisomal L-bifunctional protein (Ehhadh KO mice). In vitro experiments using HEK-293 KO cell lines demonstrate that ABCD3 and ACOX1 are essential in DCA β-oxidation, whereas both the bifunctional proteins (EHHADH and HSD17B4) and the thiolases (ACAA1 and SCPx) have overlapping functions and their contribution may depend on expression level. We also show that medium-chain 3-hydroxydicarboxylic aciduria is a prominent feature of EHHADH deficiency in mice most notably upon inhibition of mitochondrial fatty acid oxidation. Using stable isotope tracing methodology, we confirmed that products of peroxisomal DCA β-oxidation can be transported to mitochondria for further metabolism. Finally, we show that, in liver, Ehhadh KO mice have increased mRNA and protein expression of cholesterol biosynthesis enzymes with decreased (in females) or similar (in males) rate of cholesterol synthesis. We conclude that EHHADH plays an essential role in the metabolism of medium-chain DCAs and postulate that peroxisomal DCA β-oxidation is a regulator of hepatic cholesterol biosynthesis.

scholarly journals The Aromatase Knockout Mouse Presents with a Sexually Dimorphic Disruption to Cholesterol Homeostasis

Endocrinology ◽  
2003 ◽  
Vol 144 (9) ◽  
pp. 3895-3903 ◽  
Author(s):  
Kylie N. Hewitt ◽  
Wah Chin Boon ◽  
Yoko Murata ◽  
Margaret E. E. Jones ◽  
Evan R. Simpson
Keyword(s):  
Elevated Serum ◽  
Dietary Cholesterol ◽  
Cholesterol Homeostasis ◽  
High Cholesterol Diet ◽  
Atp Binding ◽  
Sexually Dimorphic ◽  
Hepatic Cholesterol ◽  
Wild Type ◽  
High Cholesterol ◽  
Atp Binding Cassette

Abstract The aromatase knockout (ArKO) mouse cannot synthesize endogenous estrogens due to disruption of the Cyp19 gene. We have shown previously, that ArKO mice present with age-progressive obesity and hepatic steatosis, and by 1 yr of age both male and female ArKO mice develop hypercholesterolemia. In this present study 10- to 12-wk-old ArKO mice were challenged for 90 d with high cholesterol diets. Our results show a sexually dimorphic response to estrogen deficiency in terms of cholesterol homeostasis in the liver. ArKO females presented with elevated serum cholesterol; conversely, ArKO males had elevated hepatic cholesterol levels. In response to dietary cholesterol, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase transcript levels were significantly reduced in females, whereas males showed more modest changes. Neither low density lipoprotein nor sterol regulatory element-binding protein expression levels were significantly altered by diet or genotype. The expression of Cyp7a, which encodes cholesterol 7α-hydroxylase, was significantly reduced in ArKO females compared with wild-type females and was increased by cholesterol feeding. Cyp7a expression was significantly elevated in the wild-type males on the high cholesterol diet, although no difference was seen between genotypes on the control diet. The ATP-binding cassette G5 and ATP-binding cassette G8 transporters do not appear to be regulated by estrogen. The expression of acyl-coenzyme A:cholesterol acyltransferase 2 showed a sexually dimorphic response, where estrogen appeared to have a stimulatory effect in females, but not males. This study reveals a sexually dimorphic difference in mouse hepatic cholesterol homeostasis and roles for estrogen in the regulation of cholesterol uptake, biosynthesis, and catabolism in the female, but not in the male.

scholarly journals SP410Microbiota dysbiosis contributes to liver injury in apolipoprotein knockout mice through the disruption of cholesterol homeostasis

2019 ◽  
Vol 34 (Supplement_1) ◽  
Author(s):  
Pei-Pei Chen ◽  
Hu Ze Bo ◽  
Lu Jian ◽  
Chen-Chen Lu ◽  
Jia Xiu Zhang ◽  
...  
Keyword(s):  
Liver Injury ◽  
Knockout Mice ◽  
Cholesterol Homeostasis
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