scholarly journals Inhibition of cholesterol biosynthesis through RNF145-dependent ubiquitination of SCAP

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Li Zhang ◽  
Prashant Rajbhandari ◽  
Christina Priest ◽  
Jaspreet Sandhu ◽  
Xiaohui Wu ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Plasma Cholesterol ◽  
Cholesterol Biosynthesis ◽  
Cholesterol Homeostasis ◽  
High Cholesterol Diet ◽  
High Cholesterol ◽  
Cholesterol Levels ◽  
Expression Of Genes ◽  
Lysine Residues ◽  
Genetic Deletion

Cholesterol homeostasis is maintained through concerted action of the SREBPs and LXRs. Here, we report that RNF145, a previously uncharacterized ER membrane ubiquitin ligase, participates in crosstalk between these critical signaling pathways. RNF145 expression is induced in response to LXR activation and high-cholesterol diet feeding. Transduction of RNF145 into mouse liver inhibits the expression of genes involved in cholesterol biosynthesis and reduces plasma cholesterol levels. Conversely, acute suppression of RNF145 via shRNA-mediated knockdown, or chronic inactivation of RNF145 by genetic deletion, potentiates the expression of cholesterol biosynthetic genes and increases cholesterol levels both in liver and plasma. Mechanistic studies show that RNF145 triggers ubiquitination of SCAP on lysine residues within a cytoplasmic loop essential for COPII binding, potentially inhibiting its transport to Golgi and subsequent processing of SREBP-2. These findings define an additional mechanism linking hepatic sterol levels to the reciprocal actions of the SREBP-2 and LXR pathways.

Pharmacological activation of LXR in utero directly influences ABC transporter expression and function in mice but does not affect adult cholesterol metabolism

2008 ◽  
Vol 295 (6) ◽  
pp. E1341-E1348 ◽  
Author(s):  
E. M. E. van Straten ◽  
N. C. A. Huijkman ◽  
J. F. W. Baller ◽  
F. Kuipers ◽  
T. Plösch
Keyword(s):  
Fetal Development ◽  
Cholesterol Metabolism ◽  
In Utero ◽  
Cholesterol Homeostasis ◽  
High Cholesterol Diet ◽  
Cholesterol Diet ◽  
High Cholesterol ◽  
High Fat ◽  
Hepatic Expression ◽  
Cholesterol Levels

Cholesterol is critical for several cellular functions and essential for normal fetal development. Therefore, its metabolism is tightly controlled during all life stages. The liver X receptors-α (LXRα; NR1H3) and -β (LXRβ; NR1H2) are nuclear receptors that are of key relevance in coordinating cholesterol and fatty acid metabolism. The aim of this study was to elucidate whether fetal cholesterol metabolism can be influenced in utero via pharmacological activation of LXR and whether this would have long-term effects on cholesterol homeostasis. Administration of the LXR agonist T0901317 to pregnant mice via their diet (0.015% wt/wt) led to induced fetal hepatic expression levels of the cholesterol transporter genes Abcg5/g8 and Abca1, higher plasma cholesterol levels, and lower hepatic cholesterol levels compared with controls. These profound changes during fetal development did not affect cholesterol metabolism in adulthood nor did they influence coping with a high-fat/high-cholesterol diet. This study shows that the LXR system is functional in fetal mice and susceptible to pharmacological activation. Despite massive changes in fetal cholesterol metabolism, regulatory mechanisms involved in cholesterol metabolism return to a “normal” state in offspring and allow coping with a high-fat/high-cholesterol diet.

scholarly journals High Cholesterol Diet Exacerbates Blood-Brain Barrier Disruption in LDLr–/– Mice: Impact on Cognitive Function

2020 ◽  
Vol 78 (1) ◽  
pp. 97-115
Author(s):  
Jade de Oliveira ◽  
Daiane F. Engel ◽  
Gabriela C. de Paula ◽  
Danúbia B. dos Santos ◽  
Jadna B. Lopes ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Familial Hypercholesterolemia ◽  
Blood Brain Barrier ◽  
Plasma Cholesterol ◽  
High Cholesterol Diet ◽  
Cholesterol Diet ◽  
Wild Type ◽  
High Cholesterol ◽  
Cholesterol Levels ◽  
Hypercholesterolemic Diet

Background: Evidence has revealed an association between familial hypercholesterolemia and cognitive impairment. In this regard, a connection between cognitive deficits and hippocampal blood-brain barrier (BBB) breakdown was found in low-density lipoprotein receptor knockout mice (LDLr–/–), a mouse model of familial hypercholesterolemia. Objective: Herein we investigated the impact of a hypercholesterolemic diet on cognition and BBB function in C57BL/6 wild-type and LDLr–/–mice. Methods: Animals were fed with normal or high cholesterol diets for 30 days. Thus, wild-type and LDLr–/–mice were submitted to memory paradigms. Additionally, BBB integrity was evaluated in the mice’s prefrontal cortices and hippocampi. Results: A tenfold elevation in plasma cholesterol levels of LDLr–/–mice was observed after a hypercholesterolemic diet, while in wild-type mice, the hypercholesterolemic diet exposure increased plasma cholesterol levels only moderately and did not induce cognitive impairment. LDLr–/–mice presented memory impairment regardless of the diet. We observed BBB disruption as an increased permeability to sodium fluorescein in the prefrontal cortices and hippocampi and a decrease on hippocampal claudin-5 and occludin mRNA levels in both wild-type and LDLr–/–mice treated with a hypercholesterolemic diet. The LDLr–/–mice fed with a regular diet already presented BBB dysfunction. The BBB-increased leakage in the hippocampi of LDLr–/–mice was related to high microvessel content and intense astrogliosis, which did not occur in the control mice. Conclusion: Therefore, LDLr–/–mice seem to be more susceptible to cognitive impairments and BBB damage induced by exposure to a high cholesterol diet. Finally, BBB disruption appears to be a relevant event in hypercholesterolemia-induced brain alterations.

scholarly journals Temporal and Quantitative Analysis of Atherosclerotic Lesions in Diet-Induced Hypercholesterolemic Rabbits

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Qi Yu ◽  
Yafeng Li ◽  
Ahmed Bilal Waqar ◽  
Yanli Wang ◽  
Bingqiao Huang ◽  
...  
Keyword(s):  
Plasma Cholesterol ◽  
Rabbit Model ◽  
Cellular Component ◽  
High Cholesterol Diet ◽  
Atherosclerotic Plaques ◽  
High Cholesterol ◽  
Ideal Model ◽  
Atherosclerotic Lesions ◽  
Cholesterol Levels ◽  
Transmission Electron

The diet-induced atherosclerotic rabbit is an ideal model for atherosclerosis study, but temporal changes in atherosclerotic development in hypercholesterolemic rabbits are poorly understood. Japanese white rabbits were fed a high-cholesterol diet to induce sustained hypercholesterolemia, and each group of 10–12 animals was then sacrificed at 6, 12, 16, or 28 weeks. The rabbit aortas were harvested, and the sizes of the gross and intima atherosclerotic lesions were quantified. The cellular component of macrophages (Mφs) and smooth muscle cells (SMCs) in aortic intimal lesions was also quantified by immunohistochemical staining, and the correlation between plasma cholesterol levels and the progress of atherosclerotic lesions was studied. The ultrastructure of the atherosclerotic lesions was observed by transmission electron microscopy (TEM). Widely variable atherosclerotic plaques were found from 6 weeks to 28 weeks, and the lesional progress was closely correlated with cholesterol exposure. Interestingly, a relatively reduced accumulation of Mφ, an increased numbers of SMCs, and a damaged endothelial layer were presented in advanced lesions. Moreover, SMCs were closely correlated with cholesterol exposure and lesional progress for the whole period. Cholesterol exposure directly determines atherosclerotic progress in a rabbit model, and the changes in the cellular component of advanced lesions may affect plaque stability in an atherosclerotic rabbit model.

scholarly journals Mathematical Models for Cholesterol Metabolism and Transport

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 155
Author(s):  
Fangyuan Zhang ◽  
Brittany Macshane ◽  
Ryan Searcy ◽  
Zuyi Huang
Keyword(s):  
Mathematical Models ◽  
Drug Targets ◽  
Cholesterol Metabolism ◽  
Cholesterol Biosynthesis ◽  
The Body ◽  
Cholesterol Homeostasis ◽  
Whole Body ◽  
Entire Body ◽  
High Cholesterol ◽  
Cholesterol Levels

Cholesterol is an essential component of eukaryotic cellular membranes. It is also an important precursor for making other molecules needed by the body. Cholesterol homeostasis plays an essential role in human health. Having high cholesterol can increase the chances of getting heart disease. As a result of the risks associated with high cholesterol, it is imperative that studies are conducted to determine the best course of action to reduce whole body cholesterol levels. Mathematical models can provide direction on this. By examining existing models, the suitable reactions or processes for drug targeting to lower whole-body cholesterol can be determined. This paper examines existing models in the literature that, in total, cover most of the processes involving cholesterol metabolism and transport, including: the absorption of cholesterol in the intestine; the cholesterol biosynthesis in the liver; the storage and transport of cholesterol between the intestine, the liver, blood vessels, and peripheral cells. The findings presented in these models will be discussed for potential combination to form a comprehensive model of cholesterol within the entire body, which is then taken as an in-silico patient for identifying drug targets, screening drugs, and designing intervention strategies to regulate cholesterol levels in the human body.

scholarly journals MicroRNA 27a Is a Key Modulator of Cholesterol Biosynthesis

2020 ◽  
Vol 40 (9) ◽  
Author(s):  
Abrar A. Khan ◽  
Heena Agarwal ◽  
S. Santosh Reddy ◽  
Vikas Arige ◽  
Bhargavi Natarajan ◽  
...  
Keyword(s):  
Posttranscriptional Regulation ◽  
Therapeutic Potential ◽  
Plasma Cholesterol ◽  
Strong Predictor ◽  
Cholesterol Biosynthesis ◽  
High Cholesterol Diet ◽  
Biosynthesis Pathway ◽  
Cholesterol Levels ◽  
Cholesterol Biosynthesis Pathway ◽  
Early Growth Response 1

ABSTRACT Hypercholesterolemia is a strong predictor of cardiovascular diseases. The 3-hydroxy-3-methylglutaryl coenzyme A reductase gene (Hmgcr) coding for the rate-limiting enzyme in the cholesterol biosynthesis pathway is a crucial regulator of plasma cholesterol levels. However, the posttranscriptional regulation of Hmgcr remains poorly understood. The main objective of this study was to explore the role of microRNAs (miRNAs) in the regulation of Hmgcr expression. Systematic in silico predictions and experimental analyses reveal that miRNA 27a (miR-27a) specifically interacts with the Hmgcr 3′ untranslated region in murine and human hepatocytes. Moreover, our data show that Hmgcr expression is inversely correlated with miR-27a levels in various cultured cell lines and in human and rodent tissues. Actinomycin D chase assays and relevant experiments demonstrate that miR-27a regulates Hmgcr by translational attenuation followed by mRNA degradation. Early growth response 1 (Egr1) regulates miR-27a expression under basal and cholesterol-modulated conditions. miR-27a augmentation via tail vein injection of miR-27a mimic in high-cholesterol-diet-fed Apoe−/− mice shows downregulation of hepatic Hmgcr and plasma cholesterol levels. Pathway and gene expression analyses show that miR-27a also targets several other genes (apart from Hmgcr) in the cholesterol biosynthesis pathway. Taken together, miR-27a emerges as a key regulator of cholesterol biosynthesis and has therapeutic potential for the clinical management of hypercholesterolemia.

scholarly journals MicroRNA-27a is a key modulator of cholesterol biosynthesis

2018 ◽  
Author(s):  
Abrar A. Khan ◽  
Heena Agarwal ◽  
S. Santosh Reddy ◽  
Vikas Arige ◽  
Vinayak Gupta ◽  
...  
Keyword(s):  
Therapeutic Potential ◽  
Plasma Cholesterol ◽  
Strong Predictor ◽  
Cholesterol Biosynthesis ◽  
High Cholesterol Diet ◽  
Biosynthesis Pathway ◽  
Cholesterol Levels ◽  
Cholesterol Biosynthesis Pathway ◽  
Early Growth Response 1 ◽  
Post Transcriptional Regulation

ABSTRACTHypercholesterolemia is a strong predictor of cardiovascular diseases. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase gene (Hmgcr) coding for the rate-limiting enzyme in the cholesterol biosynthesis pathway is a crucial regulator of plasma cholesterol levels. However, the post-transcriptional regulation of Hmgcr remains poorly understood. The main objective of this study was to explore the role of miRNAs in the regulation of Hmgcr expression. Systematic in silico predictions and experimental analyses reveal that miR-27a specifically interacts with the Hmgcr 3’-untranslated region in murine and human hepatocytes. Moreover, our data shows that Hmgcr expression is inversely correlated with miR-27a levels in various cultured cell lines, human and rodent tissues. Actinomycin D chase assays and relevant experiments demonstrate that miR-27a regulates Hmgcr by translational attenuation followed by mRNA degradation. Early Growth Response 1 (Egr1) regulates miR-27a expression under basal and cholesterol-modulated conditions. miR-27a augmentation via tail-vein injection of miR-27a mimic in high cholesterol diet-fed Apoe−/− mice shows down-regulation of hepatic Hmgcr and plasma cholesterol levels. Pathway and gene expression analyses show that miR-27a also targets several other genes (apart from Hmgcr) in cholesterol biosynthesis pathway. Taken together, miR-27a emerges as a key regulator of cholesterol biosynthesis and has therapeutic potential for clinical management of hypercholesterolemia.

scholarly journals Abnormal brain cholesterol homeostasis in Alzheimer’s disease—a targeted metabolomic and transcriptomic study

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Vijay R. Varma ◽  
H. Büşra Lüleci ◽  
Anup M. Oommen ◽  
Sudhir Varma ◽  
Chad T. Blackshear ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Brain Tissue ◽  
Cholesterol Metabolism ◽  
Cholesterol Biosynthesis ◽  
Cholesterol Homeostasis ◽  
Transcriptomic Data ◽  
Brain Cholesterol ◽  
Cholesterol Levels

AbstractThe role of brain cholesterol metabolism in Alzheimer’s disease (AD) remains unclear. Peripheral and brain cholesterol levels are largely independent due to the impermeability of the blood brain barrier (BBB), highlighting the importance of studying the role of brain cholesterol homeostasis in AD. We first tested whether metabolite markers of brain cholesterol biosynthesis and catabolism were altered in AD and associated with AD pathology using linear mixed-effects models in two brain autopsy samples from the Baltimore Longitudinal Study of Aging (BLSA) and the Religious Orders Study (ROS). We next tested whether genetic regulators of brain cholesterol biosynthesis and catabolism were altered in AD using the ANOVA test in publicly available brain tissue transcriptomic datasets. Finally, using regional brain transcriptomic data, we performed genome-scale metabolic network modeling to assess alterations in cholesterol biosynthesis and catabolism reactions in AD. We show that AD is associated with pervasive abnormalities in cholesterol biosynthesis and catabolism. Using transcriptomic data from Parkinson’s disease (PD) brain tissue samples, we found that gene expression alterations identified in AD were not observed in PD, suggesting that these changes may be specific to AD. Our results suggest that reduced de novo cholesterol biosynthesis may occur in response to impaired enzymatic cholesterol catabolism and efflux to maintain brain cholesterol levels in AD. This is accompanied by the accumulation of nonenzymatically generated cytotoxic oxysterols. Our results set the stage for experimental studies to address whether abnormalities in cholesterol metabolism are plausible therapeutic targets in AD.

scholarly journals Treatment with Lobeglitazone Attenuates Hepatic Steatosis in Diet-Induced Obese Mice

PPAR Research ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Sorim Choung ◽  
Kyong Hye Joung ◽  
Bo Ram You ◽  
Sang Ki Park ◽  
Hyun Jin Kim ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Hepatic Steatosis ◽  
Plasma Cholesterol ◽  
Cholesterol Biosynthesis ◽  
Peroxisome Proliferator ◽  
Obese Mice ◽  
Nonalcoholic Fatty Liver ◽  
Hepatic Lipid ◽  
Hepatic Expression ◽  
Expression Of Genes

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with insulin resistance. The peroxisome proliferator-activated receptor (PPAR) activators, thiazolidinediones, (TZDs), are insulin sensitizers used as a treatment for NAFLD. However, TZDs are a controversial treatment for NAFLD because of conflicting results regarding hepatic steatosis and fibrosis. To evaluate a possible effective drug for treatment of NAFLD, we investigated the effects of a newly developed TZD, lobeglitazone, with an emphasis on hepatic lipid metabolism. Lobeglitazone treatment for 4 weeks in high fat diet- (HFD-) induced obese mice (HL group) improved insulin resistance and glucose intolerance compared to HFD-induced obese mice (HU group). The gene levels related to hepatic gluconeogenesis also decreased after treatment by lobeglitazone. The livers of mice in the HL group showed histologically reduced lipid accumulation, with lowered total plasma cholesterol and triglyceride levels. In addition, the HL group significantly decreased the hepatic expression of genes associated with lipid synthesis, cholesterol biosynthesis, and lipid droplet development and increased the hepatic expression of genes associated with fatty acid β-oxidation, thus suggesting that lobeglitazone decreased hepatic steatosis and reversed hepatic lipid dysregulation. Livers with steatohepatitis contained increased levels of PPARγ and phosphorylated PPARγ at serine 273, leading to downregulation of expression of genes associated with insulin sensitivity. Notably, the treatment of lobeglitazone increased the protein levels of PPARα and diminished levels of PPARγ phosphorylated at serine 273, which were increased by a HFD, suggesting that induction of PPARα and posttranslational modification of PPARγ in livers by lobeglitazone might be an underlying mechanism of the improvement seen in NAFLD. Taken together, our data showed that lobeglitazone might be an effective treatment for NAFLD.

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