Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0242339 (dyslipidemia)
 13,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rev-erbbeta is an orphan nuclear receptor that selectively blocks trans-activation mediated by the retinoic acid-related orphan receptor-alpha (RORalpha). RORalpha has been implicated in the regulation of high density lipoprotein cholesterol, lipid homeostasis, and inflammation. Reverbbeta and RORalpha are expressed in similar tissues, including skeletal muscle; however, the pathophysiological function of Rev-erbbeta has remained obscure. We hypothesize from the similar expression patterns, target genes, and overlapping cognate sequences of these nuclear receptors that Rev-erbbeta regulates lipid metabolism in skeletal muscle. This lean tissue accounts for >30% of total body weight and 50% of energy expenditure. Moreover, this metabolically demanding tissue is a primary site of glucose disposal, fatty acid oxidation, and cholesterol efflux. Consequently, muscle has a significant role in insulin sensitivity, obesity, and the blood-lipid profile. We utilize ectopic expression in skeletal muscle cells to understand the regulatory role of Rev-erbbeta in this major mass peripheral tissue. Exogenous expression of a dominant negative version of mouse Rev-erbbeta decreases the expression of many genes involved in fatty acid/lipid absorption (including Cd36, and Fabp-3 and -4). Interestingly, we observed a robust induction (>15-fold) in mRNA expression of interleukin-6, an "exercise-induced myokine" that regulates energy expenditure and inflammation. Furthermore, we observed the dramatic repression (>20-fold) of myostatin mRNA, another myokine that is a negative regulator of muscle hypertrophy and hyperplasia that impacts on body fat accumulation. This study implicates Rev-erbbeta in the control of lipid and energy homoeostasis in skeletal muscle. In conclusion, we speculate that selective modulators of Rev-erbbeta may have therapeutic utility in the treatment of dyslipidemia and regulation of muscle growth.
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PMID:Rev-erbbeta regulates the expression of genes involved in lipid absorption in skeletal muscle cells: evidence for cross-talk between orphan nuclear receptors and myokines. 1562 3

Retinoic acid receptor-related orphan receptor-alpha (RORalpha) (NR1F1) is an orphan nuclear receptor with a potential role in metabolism. Previous studies have shown that RORalpha regulates transcription of the murine Apolipoprotein AI gene and human Apolipoprotein CIII genes. In the present study, we present evidence that RORalpha also induces transcription of the human Apolipoprotein AV gene, a recently identified apolipoprotein associated with triglyceride levels. Adenovirus-mediated overexpression of RORalpha increased the endogenous expression of ApoAV in HepG2 cells and RORalpha also enhanced the activity of an ApoAV promoter construct in transiently transfected HepG2 cells. Deletion and mutation studies identified three AGGTCA motifs in the ApoAV promoter that mediate RORalpha transactivation, one of which overlaps with a previously identified binding site for PPARalpha. Together, these results suggest a novel mechanism whereby RORalpha modulates lipid metabolism and implies RORalpha as a potential target for the treatment of dyslipidemia and atherosclerosis.
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PMID:Identification of the human ApoAV gene as a novel RORalpha target gene. 1578 Dec 55

Homozygous staggerer mice (sg/sg) display decreased and dysfunctional retinoic acid receptor-related orphan receptor alpha (RORalpha) expression. We observed decreases in serum (and liver) triglycerides and total and high density lipoprotein serum cholesterol in sg/sg mice. Moreover, the sg/sg mice were characterized by reduced adiposity (associated with decreased fat pad mass and adipocyte size). Candidate-based expression profiling demonstrated that the dyslipidemia in sg/sg mice is associated with decreased hepatic expression of SREBP-1c, and the reverse cholesterol transporters, ABCA1 and ABCG1. This is consistent with the reduced serum lipids. The molecular mechanism did not involve aberrant expression of LXR and/or ChREBP. However, ChIP and transfection analyses revealed that RORalpha is recruited to and regulates the activity of the SREBP-1c promoter. Furthermore, the lean phenotype in sg/sg mice is also characterized by significantly increased expression of PGC-1alpha, PGC-1beta, and lipin1 mRNA in liver and white and brown adipose tissue from sg/sg mice. In addition, we observed a significant 4-fold increase in beta(2)-adrenergic receptor mRNA in brown adipose tissue. Finally, dysfunctional RORalpha expression protects against diet-induced obesity. Following a 10-week high fat diet, wild-type but not sg/sg mice exhibited a approximately 20% weight gain, increased hepatic triglycerides, and notable white and brown adipose tissue accumulation. In summary, these changes in gene expression (that modulate lipid homeostasis) in metabolic tissues are involved in decreased adiposity and resistance to diet-induced obesity in the sg/sg mice, despite hyperphagia. In conclusion, we suggest this orphan nuclear receptor is a key modulator of fat accumulation and that selective ROR modulators may have utility in the treatment of obesity.
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PMID:The orphan nuclear receptor, RORalpha, regulates gene expression that controls lipid metabolism: staggerer (SG/SG) mice are resistant to diet-induced obesity. 1844 Oct 15

The hepatocyte nuclear factor 4alpha (HNF4alpha) is a liver-enriched nuclear receptor that plays a critical role in early morphogenesis, fetal liver development, liver differentiation and metabolism. Human HNF4alpha gene mutations cause maturity on-set diabetes of the young type 1, an autosomal dominant non-insulin-dependent diabetes mellitus. HNF4alpha is an orphan nuclear receptor because of which the endogenous ligand has not been firmly identified. The trans-activating activity of HNF4alpha is enhanced by interacting with co-activators and inhibited by corepressors. Recent studies have revealed that HNF4alpha plays a central role in regulation of bile acid metabolism in the liver. Bile acids are required for biliary excretion of cholesterol and metabolites, and intestinal absorption of fat, nutrients, drug and xenobiotics for transport and distribution to liver and other tissues. Bile acids are signaling molecules that activate nuclear receptors to control lipids and drug metabolism in the liver and intestine. Therefore, HNF4alpha plays a central role in coordinated regulation of bile acid and xenobiotics metabolism. Drugs that specifically activate HNF4alpha could be developed for treating metabolic diseases such as diabetes, dyslipidemia and cholestasis, as well as drug metabolism and detoxification.
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PMID:Hepatocyte nuclear factor 4alpha regulation of bile acid and drug metabolism. 1923 93

Ginsenoside Re is a protopanaxatriol-type saponin isolated from Panax ginseng berry. Although anti-diabetic and anti-hyperlipidemic effects of Re have been reported by several groups, its mechanism of action is largely unknown until now. Here, we examine anti-diabetic and anti-hyperlipidemic activities of Re and action mechanism(s) in human HepG2 hepatocytes and high-fat diet fed C57BL/6J mice. Re suppresses the hepatic glucose production via induction of orphan nuclear receptor small heterodimer partner (SHP), and inhibits lipogenesis via suppression of sterol regulatory element binding protein-1c (SREBP-1c) and its target gene [fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD1)] transcription. These effects were mediated through activation of AMP-activated protein kinase (AMPK), and abolished when HepG2 cells were treated with an AMPK inhibitor, Compound C. C57BL/6J mice were randomly divided into five groups: regular diet fed group (RD), high-fat diet fed group (HFD) and the HFD plus Re (5, 10, 20 mg/kg) groups. Re treatment groups were fed a high-fat diet for 6 weeks, and then orally administered Re once a day for 3 weeks. The in vitro results are likely to hold true in an in vivo experiment, as Re markedly lowered blood glucose and triglyceride levels and protected against hepatic steatosis in high-fat diet fed C57BL/6J mice. In conclusion, the current study suggest that ginsenoside Re improves hyperglycemia and hyperlipidemia through activation of AMPK, and confers beneficial effects on type 2 diabetic patients with insulin resistance and dyslipidemia.
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PMID:Ginsenoside Re lowers blood glucose and lipid levels via activation of AMP-activated protein kinase in HepG2 cells and high-fat diet fed mice. 2197 52