| For medical practitioners and the general public - Cholesterol Journal Article Catalog. |
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| Clinical significance of plasma total cholesterol, free cholesterol and esterified cholesterol levels Taki, M. and T. Teramoto (2004), Nippon Rinsho 62 Suppl 12: 10-3. |
| Clinical significance of small dense low-density lipoprotein cholesterol levels determined by the simple precipitation method Hirano, T., Y. Ito, et al. (2004), Arterioscler Thromb Vasc Biol 24(3): 558-63. Abstract: OBJECTIVE: Recently, we established a simple method for the quantification of small dense LDL cholesterol (C) using heparin-magnesium precipitation. The small dense LDL-C level was identical to cholesterol in the denser LDL fraction with a density of 1.044 to 1.063 g/mL. The aim of this study was to examine clinical significance of this precipitation method for small dense LDL-C. METHODS AND RESULTS: Small dense LDL-C was measured by a direct homogenous LDL-C assay in the supernatant that remained after heparin-magnesium precipitation with density <1.044 lipoproteins. In 313 normolipidemic subjects, the mean value of small dense LDL-C was 31+/-13 mg/dL. In 462 healthy subjects, small dense LDL-C levels were positively correlated with serum triglyceride and LDL-C and were inversely correlated with high-density lipoprotein cholesterol (HDL-C). Combined hyperlipidemia showed the highest small dense LDL-C level among the various types of hyperlipidemia. Patients with type 2 diabetes had an increased small dense LDL-C level (55+/-17). Patients with coronary heart disease also had increased small dense LDL-C levels (53+/-30) irrespective of the presence of diabetes, whereas their LDL-C levels were comparable to those of normolipidemic controls (111+/-31 versus 104+/-22). CONCLUSIONS: These results suggest that measurement of small dense LDL-C by the present precipitation method is useful to evaluate atherogenic risk and may be applicable to routine clinical examination. |
| Clinical study of the month. Usefulness of increasing HDL cholesterol in secondary prevention of coronary heart disease: results of the VA-HIT study Scheen, A. J. (1999), Rev Med Liege 54(9): 773-5. Abstract: The "Veterans Affairs Cooperative Studies Program High-Density Lipoprotein Cholesterol Intervention Trial" (VA-HIT) is a large randomised, double-blind, placebo-controlled clinical trial for the secondary prevention of coronary heart disease. It demonstrates that a fibrate treatment (gemfibrozil) significantly reduces the relative risk of major coronary (-22%, p = 0.006) and cardiovascular (-24%, p < 0.001) events in men with coronary heart disease whose primary lipid abnormality is a low HDL cholesterol level. These findings suggest that, in such a population, the rate of coronary events is reduced under gemfibrozil therapy by raising HDL cholesterol levels (+6%) and lowering levels of triglycerides (-31%) without lowering LDL cholesterol concentrations. |
| Clinical trial of an educational intervention to achieve recommended cholesterol levels in patients with coronary artery disease Lichtman, J. H., J. Amatruda, et al. (2004), Am Heart J 147(3): 522-8. Abstract: BACKGROUND: Despite national efforts to improve cholesterol management for patients with coronary artery disease, many patients are not reaching recommended cholesterol target levels. We sought to determine whether a nurse-based educational intervention, designed to educate patients with confirmed coronary artery disease about personal low-density lipoprotein (LDL) cholesterol target levels and encourage partnership with physicians, could increase adherence with National Cholesterol Education Program target levels (LDL cholesterol level < or =100 mg/dL). METHODS: Patients hospitalized with confirmed coronary artery disease were randomized to undergo a nurse-based educational intervention (375 patients) or usual care (381 patients) for a 12-month period after hospitalization. The primary outcome was the proportion of patients at the LDL cholesterol target level 1 year after hospitalization. The secondary outcome was the proportion of patients with accurate knowledge of LDL cholesterol target levels. RESULTS: The groups were similar at baseline in demographic and clinical characteristics, percent at LDL cholesterol target level (43.9% and 41.1%, respectively), and percent with knowledge of LDL cholesterol target levels (both 5%). The proportion of patients at LDL cholesterol target levels at 1 year did not differ between the intervention (70.2%) and usual care group (67.4%, P =.46). At the conclusion of the trial, patient knowledge about LDL cholesterol target level was higher for the intervention group than the usual care group (19.6% and 6.7%, respectively, P =.001), but this was not associated with improved cholesterol management. CONCLUSIONS: Our nurse-based educational intervention did not result in a significant increase in the proportion of patients who reached target LDL cholesterol levels 1 year after hospitalization. Although the intervention improved patient knowledge of LDL cholesterol target levels, overall rates of LDL cholesterol knowledge remained low, and it was not associated with improved cholesterol management. |
| Clinical Trials Update: CAPRICORN, COPERNICUS, MIRACLE, STAF, RITZ-2, RECOVER and RENAISSANCE and cachexia and cholesterol in heart failure. Highlights of the Scientific Sessions of the American College of Cardiology, 2001 Louis, A., J. G. Cleland, et al. (2001), Eur J Heart Fail 3(3): 381-7. Abstract: This is a synopsis of presentations made at the American College of Cardiology (ACC) in 2001 summarising recent research developments relating to heart failure. Clinical studies of particular interest to physicians with an interest in heart failure and its prevention are reviewed. The COPERNICUS trial lends further support to the use of the beta-blocker, carvedilol, in severe heart failure and the CAPRICORN trial to its use in patients with post-infarction left ventricular systolic dysfunction. The MIRACLE study reinforces the evidence from three smaller trials that cardiac resynchronisation therapy is an effective treatment for the relief of symptoms in patients with severe heart failure and cardiac dyssynchrony. The STAF trial casts further doubt on the wisdom of cardioversion as a routine strategy for the management of chronic atrial fibrillation. The RITZ-2 trial suggests that an intravenous, non-selective endothelin antagonist is effective in improving haemodynamics and symptoms and possibly in reducing morbidity in severe heart failure. Observational studies in heart failure suggest that a moderate excess of body fat and elevated blood cholesterol may be desirable in patients with heart failure, challenging the current non-evidenced-based vogue for cholesterol lowering therapy in heart failure. The RENAISSANCE and RECOVER outcome studies of etanercept, a tumour necrosis factor (TNF) receptor analogue that blocks the effect of TNF, were stopped because of lack of evidence of benefit shortly after the ACC. |
| Clinical use of statins and cholesterol goals in patients with several cardiovascular risk factors Gomez-Belda, A., E. Rodilla, et al. (2003), Med Clin (Barc) 121(14): 527-31. Abstract: BACKGROUND AND OBJECTIVE: Our goal was to determine the number of patients who achieve low-density lipoprotein cholesterol (LDL-c) targets according to new guidelines. PATIENTS AND METHOD: Descriptive and transversal study of patients from a cardiovascular clinic. LDL-c was calculated and targets were established according the NCEP-ATP III. RESULTS: 1,811 patients (46% males, 54% females) were studied. 35% of these were high-risk patients (group 1: coronary risk > 20% at 10 years), 19% were intermediate-risk patients (group 2: coronary risk 10-20% at 10 years) and 46% were low-risk patients (group 3: coronary risk < 10% at 10 years). Overall, 58% of patients achieved target LDL-c levels, yet success rates were 26% among group 1 patients, 51% among group 2 patients, and 86% among group 3 patients (p = 0.001, for differences between groups). Statin treatment was significantly related to achieving target LDL-c levels in group 1 patients (OR = 1.7; 95% CI, 1.2-2.4; p = 0.007). In group 1.41% of patients had LDL-c levels > 130 mg/dl without receiving lipid-lowering drugs. CONCLUSIONS: Although an overall 58% patients achieve target LDL-C levels, only one of four high-risk patients have LDL-c levels < 100 mg/dl, and statin treatment is a determining factor to achieve this goal. These findings indicate that a more aggressive treatment with statins is needed in secondary prevention. |
| Clinical usefulness of serum total cholesterol as an index of hypothyroidism in patients after cervical radiation Iguma, Y., C. Iwai, et al. (2003), Yakugaku Zasshi 123(2): 63-7. Abstract: Cervical radiation therapy is often applied to patients with head and neck cancers because radiation has a high sensitivity to these cancers and permits the preservation of functions and physical form. However, it has been shown that various complications can result from radiation therapy. We have encountered some patients who showed hypercholesterolemia resulting from cervical radiation. Therefore, we have paid close attention to the relationship between hypercholesterolemia after cervical radiation and hypothyroidism. Thyroid hormone tests in these patients with hypercholesterolemia after cervical radiation showed high thyroid stimulating hormone (TSH) and low free thyroxine (fT4), indicating the presence of hypothyroidism. After administration of levothyroxine Na, their fT4 levels increased and both TSH levels and serum total cholesterol levels decreased. In conclusion, in patients who have received cervical radiation, we recommend monitoring serum total cholesterol periodically to detect hypothyroidism easily before the appearance of its symptoms. |
| Clinical, epidemiologic, and biochemical findings on the reverse cholesterol transport (cholesterol-HDL) Fredenrich, A. and P. Bayer (2001), Bull Acad Natl Med 185(1): 41-5; discussion 45-7. Abstract: Contrary to high plasma levels of low-density lipoprotein cholesterol (LDL-C), closely linked with coronary heart disease (CHD), high-density lipoprotein cholesterol (HDL-C) play an antiatherogenic role, through the reverse cholesterol transport from peripheral cells to the liver. New data in the pathophysiology of a rare genetic dyslipidemia, the Tangier disease, characterized by very low HDL-C levels and premature CHD, have shed light on this complex mechanism. In this disease, cholesterol efflux from peripheral cells is dramatically reduced, and this has been recently shown to be caused by mutations in an ATP-binding cassette transporter, which normally stimulates cholesterol efflux. Reverse cholesterol transport is therefore greatly decreased. Epidemiological data have revealed that 15% to 30% of coronary patients have low HDL-C levels. However, this is often combined with high triglycerides levels, and this association is frequently found in diabetic patients, especially prone to CHD. HDL-C has been repeatedly shown to be an inverse predictor of CHD. This has been enhanced by recent interventional studies (Veterans Affairs HDL Intervention Study, Bezafibrate Infarction Prevention Study) which have provided strong evidence that pharmacological increase of HDL-C, in combination with decrease in triglycerides level, reduces incidence of CHD. |
| Clinical, pathologic, and biochemical features of a cholesterol lipidosis accompanied by hyperlipidemia and xanthomas Filling-Katz, M. R., S. P. Miller, et al. (1992), Neurology 42(9): 1768-74. Abstract: We describe the unique clinical and histopathologic features of a child with biochemical and immunocytochemical features of Niemann-Pick disease type C (NPC). Clinically, she was found to have multiple xanthomas of the upper aerodigestive tract with dysphagia and expressive language delay, splenomegaly, bony infarcts, and type IIb hyperlipidemia. Neurologic examination was otherwise normal. Microscopy revealed foam cells in her bone marrow, liver, tongue, tonsils, glottis, and in normal-appearing peritonsillar mucosa. Lipid analysis of a liver biopsy specimen showed a small increase in phospholipids, a twofold increase in sphingomyelin, a fivefold increase in cholesterol, and a marked (25-fold) increase in bis(monoacylglycerol) phosphate. Lysosomal acid hydrolase activities in cultured skin fibroblasts were nondiagnostic. Biochemical and immunocytochemical studies of cultured fibroblasts demonstrated lysosomal accumulation of unesterified LDL-derived cholesterol as well as delayed induction of homeostatic responses to endogenous cholesterol consistent with a diagnosis of NPC. Based upon these observations, we speculate that this patient could have a new phenotypic expression of NPC or represents a new cholesterol lipidosis biochemically resembling NPC. The chance occurrence of two separate lipid disorders seems less likely. |
| Clinically relevant pleiotropic effects of statins: drug properties or effects of profound cholesterol reduction? Comparato, C., C. Altana, et al. (2001), Nutr Metab Cardiovasc Dis 11(5): 328-43. Abstract: Clinical trials have firmly established that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) can induce the regression of vascular atherosclerosis and reduce cardiovascular-related morbidity and death in patients with and without coronary artery disease. It is usually assumed that these beneficial effects are due to the ability of statins to reduce cholesterol synthesis. However, because mevalonic acid is not only the precursor of cholesterol but also of many non-steroidal isoprenoid compounds, the inhibition of HMG-CoA reductase may lead to pleiotropic effects. As shown by the data reported in this review, some statins can interfere with major events involved in the formation of atherosclerotic lesions, regardless of their hypolipidemic properties. The relevance of these effects in humans remains to be established (particularly in view of the high statin doses required to produce a direct vascular action), thus their contribution to the reduction in cardiovascular events observed in clinical trials has become one of the major challenges for future studies aimed at clarifying the anti-atherosclerotic benefits of statins. |
| Clinicopathological consultation. Ear cholesteatoma versus cholesterol granuloma Ferlito, A., K. O. Devaney, et al. (1997), Ann Otol Rhinol Laryngol 106(1): 79-85. |
| Clofibrate and di(2-ethylhexyl)phthalate increase ubiquinone contents without affecting cholesterol levels Aberg, F. and E. L. Appelkvist (1994), Acta Biochim Pol 41(3): 321-9. Abstract: Induction studies were performed on liver, muscle, heart, brain and blood by feeding Sprague-Dawley rats a diet containing a peroxisome proliferator, clofibrate or di(2-ethylhexyl)phthalate. Ingestion of these drugs resulted in an increase in the amount of two different types of ubiquinone homologues UQ9 and UQ10 found in rat. Phthalate proved to be the more effective drug, leading to a highly increased amount of ubiquinone in the liver. Increases were also found in all the above-mentioned organs except the brain. The UQ9 levels were raised to 400, 200, 120 and 120%, of the respective normal values. The antioxidant and hypolipidemic agent, probucol, was used as a control to evaluate whether the increased ubiquinone level constituted a response to the elevated hydrogen peroxide pressure, resulting from the induced increase in fatty acid beta-oxidation. In the presence of probucol, ubiquinone levels were decreased in all the above-mentioned organs except heart and brain. Probucol had limited effects on the amount of cholesterol and did not significantly alter the amount of dolichol. The two peroxisome proliferators differed in their effects on cholesterol, as well as on dolichol levels which was induced by phthalate but not by clofibrate. The possible mechanisms involved, and the importance of low toxicity drugs which could elevate ubiquinone levels in various tissues, are discussed. |
| Clofibrate, a peroxisome-proliferator, enhances reverse cholesterol transport through cytochrome P450 activation and oxysterol generation Guan, J. Z., N. Tamasawa, et al. (2003), Tohoku J Exp Med 201(4): 251-9. Abstract: Fibrates are widely used hypolipidemic agents that activate the peroxisome proliferator-activated receptor a (PPARalpha) and regulate the expression of many genes involved in lipid metabolism. We studied the mechanism of the effect of clofibrate on cholesterol homeostasis. Rats were fed with chow containing clofibrate, cytochrome P-450 inhibitor ketoconazole, or clofibrate plus ketoconazole. Control rats were fed only with normal chow. The levels of six oxysterols in liver microsome were determined. The levels of mRNAs for liver X receptor alpha (LXRalpha), ATP-binding cassette A1 (ABCA1), PPARalpha and cholesterol 7alpha-hydroxylase (CYP7A) in the liver were analyzed by northern blotting. Clofibrate administration decreased plasma levels of total cholesterol and triglyceride and increased high-density lipoprotein-cholesterol (HDL-C). Clofibrate increased the levels of liver microsomal oxysterols including 25- and 27-hydroxycholesterol, which are potent activators of LXRalpha. Clofibrate also enhanced the expression of mRNAs for PPARalpha, LXRalpha, and ABCA1. Simultaneous administration of ketoconazole suppressed the effects of clofibrate on plasma lipids, hepatic oxysterol levels, and the expression of the genes. Clofibrate increases cytochrome P450 content and the resulting oxysterol generation may partly mediate the clofibrate-induced up-regulattion of LXRa and ABCA1, which are related to reverse cholesterol transport. |
| Cloning and characterization of the human stearoyl-CoA desaturase gene promoter: transcriptional activation by sterol regulatory element binding protein and repression by polyunsaturated fatty acids and cholesterol Bene, H., D. Lasky, et al. (2001), Biochem Biophys Res Commun 284(5): 1194-8. Abstract: Stearoyl-CoA desaturase (SCD) is a microsomal enzyme required for the biosynthesis of oleate (C18:1) and palmitoleate (C16:1) which are the major monounsaturated fatty acids of membrane phospholipids, triglycerides and cholesterol esters. Previously the full-length human skin cDNA was sequenced and the exon and intron structure of the single functional SCD gene determined. Here we report on the cloning and characterization of the promoter region of the human SCD gene. The human promoter structure is very similar to that of the mouse SCD1 isoform and contains conserved regulatory sequences for the binding of several transcription factors including the sterol regulatory element binding protein (SREBP), CCAAT enhancer binding protein-alpha (C/EBPalpha) and nuclear factor-1 (NF-1) that have been shown to transactivate the transcription of the mouse SCD1 gene. Polyunsaturated fatty acids and cholesterol decreased the SCD promoter-luciferase activity when transiently transfected into HepG2 cells. The decrease in promoter activity correlated with decreases in endogenous SCD mRNA and protein levels. Cotransfection experiment in HepG2 cells showed transactivation of the SCD promoter-luciferase activity by an expression vector containing SREBP-1a and 1c. Our studies indicate that the transcription of the human SCD gene is repressed by polyunsaturated fatty acids and cholesterol and that SREBP plays a role in the transcriptional activation of this gene. |
| Cloning and expression of a cellular high density lipoprotein-binding protein that is up-regulated by cholesterol loading of cells McKnight, G. L., J. Reasoner, et al. (1992), J Biol Chem 267(17): 12131-41. Abstract: Plasma membranes of cultured cells contain high affinity receptors for high density lipoprotein (HDL) that appear to mediate removal of excess intracellular cholesterol. Recent studies using ligand blot analysis have identified a 110-kDa membrane protein which has features predicted for an HDL receptor, in that it preferentially binds HDL apolipoproteins and undergoes up-regulation in response to cholesterol loading of cells. In this study, we isolated a cDNA clone from an expression library using an antibody raised against partially purified 110-kDa HDL-binding protein. This clone encodes a novel cell protein, designated HBP, comprised mostly of 14 imperfect tandem repeats of approximately 70 amino acids in length. Each repeat appears to contain two amphipathic helices. Expression of HBP in cultured cells was increased severalfold when cells were loaded with cholesterol, as evident by increases in both HBP mRNA and membrane-associated protein. Overexpression of HBP in mammalian cell transfectants was associated with higher HDL binding to isolated cell protein and with modest increases in HDL binding to the cell surface. Proteins identified by ligand blot analysis had lower apparent M(r) than the primary HBP gene product and varied in M(r) and in HDL binding activity between cell types, suggesting that HBP undergoes cell-specific processing. These results provide preliminary evidence that HBP is a component of a cellular pathway that facilitates removal of excess cholesterol from cells, perhaps through its interaction with HDL. However, the predicted structure of HBP does not conform to that of any known receptor, suggesting that it does not function as a classic plasma membrane receptor. |
| Cloning and in vitro expression of rat lecithin:cholesterol acyltransferase Wang, J., A. K. Gebre, et al. (1997), Biochim Biophys Acta 1346(3): 207-11. Abstract: Rat lecithin:cholesterol acyltransferase (LCAT) cDNA was obtained by reverse transcriptase/polymerase chain reaction amplification of rat liver total RNA. A consensus sequence was derived from four independent clones from two strains of rats. In vitro expression of rat LCAT cDNA in COS cells resulted in secreted enzyme protein with the same fatty acyl specificity for phospholipase A2 activity and cholesterol esterification as rat plasma LCAT, but different from that of recombinant or human plasma LCAT. |
| Cloning and regulation of cholesterol 7 alpha-hydroxylase, the rate-limiting enzyme in bile acid biosynthesis Jelinek, D. F., S. Andersson, et al. (1990), J Biol Chem 265(14): 8190-7. Abstract: The rate-limiting step in bile acid biosynthesis is catalyzed by the microsomal cytochrome P-450 cholesterol 7 alpha-hydroxylase (7 alpha-hydroxylase). The expression of this enzyme is subject to feedback regulation by sterols and is thought to be coordinately regulated with enzymes in the cholesterol supply pathways, including the low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl-coenzyme A reductase and synthase. Here we report the purification of rat 7 alpha-hydroxylase and the determination of a partial amino acid sequence. Oligonucleotides derived from peptide sequence were used to clone a full-length cDNA encoding 7 alpha-hydroxylase. DNA sequence analysis of the cDNA revealed a 7 alpha-hydroxylase protein of 503 amino acids with a predicted molecular weight of 56,890 which represents a novel family of cytochrome P-450 enzymes. Transfection of a 7 alpha-hydroxylase cDNA into simian COS cells resulted in the synthesis of a functional enzyme whose activity was stimulated in vitro by the addition of rat microsomal cytochrome P-450 reductase protein. RNA blot hybridization experiments indicated that the mRNA for 7 alpha-hydroxylase is found only in the liver. The levels of this mRNA increased when bile acids were depleted by dietary cholestyramine and decreased when bile acids were consumed. Dietary cholesterol led to an increase in 7 alpha-hydroxylase mRNA levels. The enzymatic activity of 7 alpha-hydroxylase paralleled the observed changes in mRNA levels. These results suggest that bile acids and sterols are able to alter the transcription of the 7 alpha-hydroxylase gene and that this control explains the previously observed feedback regulation of bile acid synthesis. |
| Cloning of factors related to HIV-inducible LBP proteins that regulate steroidogenic factor-1-independent human placental transcription of the cholesterol side-chain cleavage enzyme, P450scc Huang, N. and W. L. Miller (2000), J Biol Chem 275(4): 2852-8. Abstract: The cholesterol side-chain cleavage enzyme, cytochrome P450scc, initiates the biosynthesis of all steroid hormones. Adrenal and gonadal strategies for P450scc gene transcription are essentially identical and depend on the orphan nuclear receptor steroidogenic factor-1, but the placental strategy for transcription of P450scc employs cis-acting elements different from those used in the adrenal strategy and is independent of steroidogenic factor-1. Because placental expression of P450scc is required for human pregnancy, we sought factors that bind to the -155/-131 region of the human P450scc promoter, which participates in its placental but not adrenal or gonadal transcription. A yeast one-hybrid screen of 2.4 x 10(6) cDNA clones from human placental JEG-3 cells yielded two unique clones; one is the previously described transcription factor LBP-1b, which is induced by HIV, type I infection of lymphocytes, and the other is a new factor, termed LBP-9, that shares 83% amino acid sequence identity with LBP-1b. When expressed in transfected yeast, both factors bound specifically to the -155/-131 DNA; antisera to LBP proteins supershifted the LBP-9.DNA complex and inhibited formation of the LBP-1b.DNA complex. Reverse transcriptase-polymerase chain reaction detected LBP-1b in human placental JEG-3, adrenal NCI-H295A, liver HepG2, cervical HeLa, and monkey kidney COS-1 cells, but LBP-9 was detected only in JEG-3 cells. When the -155/-131 fragment was linked to a minimal promoter, co-expression of LBP-1b increased transcription 21-fold in a dose-dependent fashion, but addition of LBP-9 suppressed the stimulatory effect of LBP-1b. The roles of LBP transcription factors in normal human physiology have been unclear. Their modulation of placental but not adrenal P450scc transcription underscores the distinctiveness of placental strategies for steroidogenic enzyme gene transcription. |
| Cloning of rabbit LCAT cDNA: increase in LCAT mRNA abundance in the liver of cholesterol-fed rabbits Murata, Y., E. Maeda, et al. (1996), J Lipid Res 37(7): 1616-22. Abstract: Structure of rabbit lecithin:cholesterol acyltransferase (LCAT) and molecular basis for the effects of cholesterol feeding on LCAT expression were investigated by cloning and sequencing LCAT cDNA from rabbit. The rabbit and human sequences are 91% identical at the nucleotide level and 93% identical at the amino acid level. The interfacial substrate active site, asparagine-linked glycosylation sites, and sites at which rare mutations cause human familial LCAT deficiency are all highly conserved in the rabbit protein. The apparent molecular mass of rabbit LCAT, as determined by immunoblot analysis, was approximately equal to that of human LCAT. Rabbits showed 2.6- and 5.5-fold increases in serum LCAT activity 3 and 6 weeks, respectively, after switching to a cholesterol-enriched diet. Northern blot analysis revealed that the abundance of LCAT mRNA in liver increased 1.6- and 2.8-fold after 3 and 6 weeks, respectively, of cholesterol feeding. The marked temporal relation between the increase in serum LCAT activity and the liver LCAT mRNA abundance suggest that the regulation of LCAT activity in vivo may be primarily determined by changes in the amount of LCAT mRNA. |
| Cloning, nucleotide sequence, and transcriptional analysis of the NAD(P)-dependent cholesterol dehydrogenase gene from a Nocardia sp. and its hyperexpression in Streptomyces spp Horinouchi, S., H. Ishizuka, et al. (1991), Appl Environ Microbiol 57(5): 1386-93. Abstract: NAD(P)-dependent cholesterol dehydrogenases NAD(P)-CDH, which allow easier quantification of cholesterol by means of directly measuring the A340 of NAD(P)H, are useful for clinical purposes. The amino acid sequences of the NH2 terminus and the fragments obtained by CNBr decomposition of the NAD(P)-CDH from a Nocardia sp. were determined for preparation of synthetic oligonucleotides as hybridization probes. A 4.4-kbp BamHI fragment hybridizing to these probes was cloned on pUC19 in Escherichia coli. The nucleotide sequence together with the determined amino acid sequences revealed that this enzyme consists of 364 amino acids (Mr, 39,792) and contains an NAD(P)-binding consensus sequence at its NH2-terminal portion. High-resolution S1 nuclease mapping suggested that in NAD(P)-CDH of both Nocardia and Streptomyces spp. transcription initiates at the adenine residue, which is the first position of the translational initiation triplet (AUG) of this protein. The S1 mapping experiments also showed that cholesterol-dependent regulation in the Nocardia sp. occurred at the level of transcription. In Streptomyces lividans containing the cloned fragment, however, this promoter was expressed constitutively. DNA manipulation of the cloned gene in E. coli, including the generation of a ribosome-binding sequence at an appropriate position by oligonucleotide-directed mutagenesis, led to production of this protein in a very large amount but in the enzymatically inactive form of inclusion bodies. On the other hand, a Streptomyces host-vector system was successfully used for producing 40 times as much enzymatically active NAD(P)-CDH as that produced by the original Nocardia sp. |