Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sterol storage disorder cerebrotendinous xanthomatosis (CTX) is characterized by abnormal deposition of cholesterol and cholestanol in multiple tissues. Deposition in the central nervous system leads to neurological dysfunction marked by dementia, spinal cord paresis, and cerebellar ataxia. Deposition in other tissues causes tendon xanthomas, premature atherosclerosis, and cataracts. In two unrelated patients with CTX, we have identified different point mutations in the gene (CYP27) encoding sterol 27-hydroxylase, a key enzyme in the bile acid biosynthesis pathway. Transfection of mutant cDNAs into cultured cells results in the synthesis of immunoreactive sterol 27-hydroxylase protein with greatly diminished enzyme activity. We have localized the CYP27 gene to the q33-qter interval of human chromosome 2, and to mouse chromosome 1, in agreement with the autosomal recessive inheritance pattern of CTX. These findings underscore the essential role played by sterols in the central nervous system and suggest that mutations in other sterol metabolizing enzymes may contribute to diseases with neurological manifestations.
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PMID:Mutations in the bile acid biosynthetic enzyme sterol 27-hydroxylase underlie cerebrotendinous xanthomatosis. 201 2

The water-insoluble cholesterol-cholestanol-water adduct C-C-2W, chemical and physical cause of atherosclerosis and gallstones, has now been found in tendinous xanthoma as well; C-C-2W, and not cholestanol, is the initial compound deposited in hereditary CTX (cerebrotendinous xanthomatosis). From these and other findings it is theorized that what have been termed cholesterol or cholestanol lipidoses should instead be characterized as C-C-2W lipidoses. More than 1 mg of cholestanol . H2O present in the body causes crystallizaion of C-C-2W . This happens when the steroid meets cholesterol . H2O in sufficient concentration to reach a solubility product of 10(-7) mg/ml. In this light the literature can be interpreted to indicate that C-C-2W exerts negative effects on liver, intima tissue, eyes, lungs, and other parts of the body. Those effects include inflammation, cell necrosis, destruction of cell membranes, abnormal growth and, perhaps, neoplastic activity. Up to 200 g of C-C-2W in the body may be tolerated if evenly spread but not if localized in one or two areas only; e.g., the brain or the cardiovascular system. It is estimated that about 1000 g of C-C-2W, even if spread, are beyond the limit of human tolerance.
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PMID:A new unified theory: C-C-2W is the chemical cause of all so-called cholesterol and cholestanol lipidoses. 677 47

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid-storage disease caused by mutations in the sterol 27 hydroxylase gene (CYP27). Clinically, a multitude of neurological, skeletal, and vascular manifestations are usually present. Premature atherosclerosis has been reported in CTX and may be related to the metabolic derangement caused by the deficiency of the enzyme. A CYP27 nonsense mutation created by the deletion of cytosine376 has been identified in four Israeli Druze CTX patients residing in the same village. Molecular screening for this mutation in families of two probands revealed a total of 10 homozygotes and 28 heterozygotes whose clinical and biochemical characteristics are described. Overall, except for tendon xanthomas, most of the clinical manifestations progress with age. The CYP27 mutation was associated with modest differences in the levels of plasma total cholesterol (TC) and LDL cholesterol (LDL-C). The distribution of plasma concentrations of TC and LDL-C in the CTX families was consistent with a polygenic model. A similar model that includes also the effects of the CYP27 genotypes was not better supported by the data. It may be concluded that, in CTX, the presence of a CYP27 mutation does not significantly affect the plasma concentrations of lipids and lipoproteins. Therefore, the reported increased prevalence of atherosclerosis in this disease must be related to other factors.
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PMID:Cerebrotendinous xanthomatosis in the Israeli Druze: molecular genetics and phenotypic characteristics. 797 52

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disease caused by mutations in the cytochrome P450(27) (CYP27) gene. This disease is characterized by the accumulation of a bile alcohol, cholestanol, in diverse tissues. Accumulation in the central nervous system leads to neurological dysfunction including dementia, spinal cord paresis, and cerebellar ataxia. Accumulation in other tissues causes tendon xanthomas, premature atherosclerosis, and cataracts. In a Japanese family with CTX, we identified two points mutations in the CYP27 gene at different sites. One is a novel transversion, which substitutes G for C at Pro 368 (CCC) to Arg (CGC). The other is a transition, which substitutes A for G at Arg441 (CGG) to Gln (CAG), this being the same mutation that Kim et al. reported (1994. J. Lipid Res. 35: 1031 - 1039). Allele-specific polymerase chain reaction analysis indicated that the father and mother of this family, who themselves had no clinical manifestations of CTX, had the former and latter mutations heterozygously, respectively. On the other hand, the patients each had both mutations heterozygously. These results are highly suggestive, but not conclusive, that the newly identified transversion in the CYP27 gene accounts for the sterol 27-hydroxylase (EC 1.14.13.15) deficiency in these patients.
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PMID:A novel mutation in the cytochrome P450(27) (CYP27) gene caused cerebrotendinous xanthomatosis in a Japanese family. 872 24

Recent evidence suggests that sterol 27-hydroxylase may play a role in cholesterol homeostasis and affect atherogenesis. The major objective of the study was to map and characterize the sterol 27-hydroxylase (CYP27) promoter region. Here we show that CYP27 gene has a TATA-less promoter and transcription initiates at a cluster of sites. The basic promoter is located between -166 and -187 bp from the translation initiation site. Possible positive transcription regulation sites are located at position -187 to -320 and -857 to -1087 bp. A negative transcription regulator site is located in position -320 to -413 bp. An enhancer sequence is located upstream to position -1087. CYP27 is upregulated by dexamethasone and downregulated by cyclosporin A and cholic acid. The dexamethasone responsive element is located between 1087 and 678 bp upstream to the putative ATG. Cyclosporin A affects bile acid metabolism by repressing CYP27 at the transcriptional level. The cyclosporin A- responsive element is mapped to between 1087 and 4000 bp upstream of the ATG. Cholic acid represses sterol 27-hydroxylase mRNA level by affecting the stability of its mRNA. The results obtained here imply that CYP27 has a potentially important role in cholesterol homeostasis in human cells, and is regulated by several substances that were previously shown to affect bile acid metabolism.
Atherosclerosis 2001 Jun
PMID:Transcriptional regulation of the human sterol 27-hydroxylase gene (CYP27) and promoter mapping. 1139 30

Statins decrease the hepatic biosynthesis of cholesterol, and reduce the incidence of myocardial infarction in women who have already experienced a myocardial infarction. Statins also reduce the risk of atherosclerosis in diabetic patients, but it is unknown whether they influence the glucose tolerance. It has further been suggested that they may influence bone metabolism. Vitamin C is an antioxidant and it decreases serum cholesterol moderately. Antioxidants may also have other metabolic effects, but these are insufficiently studied. The aim of the present study was to investigate the metabolic effects of the cholesterol-lowering agent fluvastatin and the antioxidant vitamin C. Sixty-eight elderly, postmenopausal women with osteoporosis and mild hypercholesterolemia were randomly assigned to 12 weeks open treatment with either fluvastatin (40 mg daily) + 500 mg vitamin C (n = 45) or vitamin C only (n = 23). We measured biochemical markers of bone formation (serum osteocalcin and total alkaline phosphatase) and bone resorption (serum and urinary CTX), parameters related to diabetes and serum lipids and lipoproteins. Fluvastatin in combination with vitamin C had no effect on bone formation markers. We found a weak decrease in parameters of bone resorption, which was significant from baseline, but not different between the two groups. There were no significant effects on any of the other markers of either fluvastatin or vitamin C. The lipid-lowering effect of fluvastatin was confirmed with a decrease of 20% and 30% in serum total cholesterol and LDL-cholesterol, respectively. We conclude that fluvastatin given in clinically relevant doses has no influence on parameters of bone remodeling. Other statins remain to be investigated.
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PMID:The effect of fluvastatin on parameters of bone remodeling. 1144 86

The CYP27 gene is expressed in arterial endothelium, macrophages, and other tissues. The gene product generates sterol intermediates that function as ligands for nuclear receptors prior to their transport to the liver for metabolism, mostly to bile acids. Most attention has been given to 27-hydroxycholesterol as a ligand for LXR activated receptors and to chenodeoxycholic acid as a ligand for farnesoid X activated receptors (FXRs). Expression of the pathway in macrophages is essential for normal reverse cholesterol transport. Thus, ABC transporter activity is upregulated, which enhances cholesterol efflux. Absence of these mechanisms probably accounts for the accelerated atherosclerosis that occurs in cerebrotendinous xanthomatosis. Accumulation of 27-hydroxycholesterol in human atheroma is puzzling and may reflect low levels of oxysterol 7alpha-hydroxylase activity in human macrophages. The same enzyme determines the proportion of mono-, di-, and tri-hydroxy bile acids synthesized in the liver. Oxysterol 7alpha-hydroxylase deficiency is a molecular basis for cholestatic liver disease. Chenodeoxycholic acid, the major normal end product, downregulates expression of cholesterol 7alpha-hydroxylase via the FXR/short heterodimer protein nuclear receptor and thus limits total bile acid production. The challenge is to quantify in a physiologic setting the magnitude of the pathway in different tissues and to further evaluate the biologic roles of all the intermediates that may function as ligands for orphan nuclear receptors or via other regulatory mechanisms.
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PMID:25R,26-Hydroxycholesterol revisited: synthesis, metabolism, and biologic roles. 1197 35

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive lipid-storage disorder characterised by xanthomas, neurological dysfunctions and premature atherosclerosis. A case of a well differentiated adenocarcinoma of the gallbladder occurring in a 57-year-old Japanese man with CTX, confirmed clinically, biochemically and at autopsy is reported together with analyses of the sterol 27-hydroxylase (CYP27) and p53 genes. A missense mutation of the p53 (G for C) was detected in the gallbladder adenocarcinoma. Direct sequence analysis also showed a silent mutational substitution of unknown significance, C for A, in CYP27 at codon 89. In the past, CTX patients have only demonstrated this infrequently, indicating no direct relationship between CYP27 dysfunction and tumour development. Thus, the present case of gallbladder cancer appears to be a chance occurrence.
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PMID:An autopsy case of gallbladder cancer developing in a Japanese man with cerebrotendinous xanthomatosis: genetic analysis of the sterol 27-hydroxylase and p53 genes. 1274 62

Cholesterol uptake and efflux are key metabolic processes associated with macrophage physiology and atherosclerosis. Peroxisome proliferator-activated receptor gamma (PPARgamma) and liver X receptor alpha (LXRalpha) have been linked to the regulation of these processes. It remains to be identified how activation of these receptors is connected and regulated by endogenous lipid molecules. We identified CYP27, a p450 enzyme, as a link between retinoid, PPARgamma, and LXR signaling. We show that the human CYP27 gene is under coupled regulation by retinoids and ligands of PPARs via a PPAR-retinoic acid receptor response element in its promoter. Induction of the enzyme's expression results in an increased level of 27-hydroxycholesterol and upregulation of LXR-mediated processes. Upregulated CYP27 activity also leads to LXR-independent elimination of CYP27 metabolites as an alternative means of cholesterol efflux. Moreover, human macrophage-rich atherosclerotic lesions have an increased level of retinoid-, PPARgamma-, and LXR-regulated gene expression and also enhanced CYP27 levels. Our findings suggest that nuclear receptor-regulated CYP27 expression is likely to be a key integrator of retinoic acid receptor-PPARgamma-LXR signaling, relying on natural ligands and contributing to lipid metabolism in macrophages.
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PMID:Transcriptional regulation of human CYP27 integrates retinoid, peroxisome proliferator-activated receptor, and liver X receptor signaling in macrophages. 1534 76

Extrahepatic sterol 27-hydroxylase (CYP27) appears to have a role in the elimination of excess cholesterol from various cells, particularly macrophages, and there is a net flux of 27-hydroxyycholesterol and its metabolites from different extrahepatic sources to the liver. In this study we tested the hypothesis that patients with advanced atherosclerosis may have higher levels of 27-oxygenated products in the circulation than control subjects. Concordant with previous studies, a strong correlation was observed between circulating levels of 27-hydroxycholesterol and cholesterol, in both healthy subjects and subjects with hypercholesterolemia and documented atherosclerosis. A group of male subjects with normal or only slightly elevated serum cholesterol and rapidly progressing carotid atherosclerosis (n = 20) had serum levels of 27-oxygenated cholesterol not statistically different from those of a matched group of subjects with little or no development of atherosclerosis (n = 20). The situation was similar in a group of patients (n = 20) with advanced general atherosclerosis associated with severe clinical symptoms. Among the two groups of patients with atherosclerosis, a few patients had relatively high levels of 27-oxygenated products. Among the healthy controls, two healthy volunteers (brother and sister) were found to have high levels of 27-hydroxycholesterol, most probably due to genetic reasons. The possibility is discussed that the high levels of 27-oxygenated products in the circulation of a few patients with atherosclerosis may be related to high amounts of active macrophages present in atherosclerotic lesions. In view of the number of factors that could affect the levels in the circulation, other explanations cannot be ruled out. At the present state of knowledge, measurements of circulating levels of 27-oxygenated metabolites do not seem to add useful information about the atherosclerotic process.
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PMID:Patients with atherosclerosis may have increased circulating levels of 27-hydroxycholesterol and cholestenoic acid. 1608 59


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