Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.8.2 (CPT)
 3,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The selective inhibition of individual carnitine acyltransferases may be useful in the therapy of diabetes and heart disease. Aminocarnitine (3) is a weak competitive inhibitor (K(i) = 4.0 mM) for carnitine acetyltransferase (CAT), although the N-acetyl derivative 4 is about 165 times more potent (K(i) = 0.024 mM) than 3. Compound 3 is also a potent competitive inhibitor for carnitine palmitoyltransferases 1 and 2 (CPT-1 and CPT-2) (IC50 for CPT-2 = 805 nM). We synthesized 3-amino-5,5-dimethylhexanoic acid (7) and its N-acetyl derivative (8) as isosteric analogs of 3 and 4 that lack the quaternary ammonium positive charge. Like 3 and 4, compounds 7 and 8 were competitive inhibitors of CAT with significantly different potencies, but in this case, 8 (K(i) = 25 mM) was 10 times less potent than 7 (K(i) = 2.5 mM). R-(-)-7 and S-(+)-7 were stereoselective inhibitors of CAT (K(i) = 1.9 and 9.2 mM, respectively). Racemic 7 was a weak competitive inhibitor of CPT-2 (K(i) = 20 mM) and had no effect on CPT-1. These results are consistent with differences among the carnitine-binding sites on carnitine acyl-transferases that may be useful in selective inhibitor design. Furthermore, the data suggest that the quaternary ammonium positive charge of carnitine may be important for the proper orientation of carnitine and its analogs in the binding site.
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PMID:3-Amino-5,5-dimethylhexanoic acid. Synthesis, resolution, and effects on carnitine acyltransferases. 793 52

Mitochondrial diseases are heterogeneous and characterized by a primary defect of the mitochondrial energy output. Genetic defects of mitochondrial energy enzymes may be due to either nuclear DNA gene mutations or mitochondrial DNA (mtDNA) mutations. Among hereditary defects of nuclear-encoded mitochondrial enzymes, carnitine palmitoyltransferase II (CPT-II) deficiency and pyruvate dehydrogenase complex (PDHC) deficiency are of major interest to the neurologist. Several mutations in the CPT-II gene as well as in the X-linked E1 alpha subunit gene of PDHC have been reported and associated with different clinical phenotypes. mtDNA-related syndromes include mitochondrial encephalomyopathies (e.g. MELAS, MERRF, NARP, MIMyCa, etc.), 'pure' encephalopathies (e.g. LHON) and a few syndromes involving only non-neurological systems (e.g. Pearson's pancreas-bone marrow syndrome or diabetes mellitus). Three kinds of molecular lesions have been identified in mtDNA-related disorders: point mutations of protein-encoding mtDNA genes (mit- mutations), point mutations of mtDNA-tRNA genes (syn- mutations) and large-scale rearrangements of mtDNA (rho- mutations). Point mutations (mit- and syn+) are usually maternally inherited, while single large-scale mtDNA rearrangements are usually sporadic. Furthermore, mendelian traits leading to either qualitative or quantitative abnormalities of mtDNA (i.e. multiple mtDNA deletions and tissue-specific mtDNA depletion, respectively) are the first examples of genetic dysfunction of nuclear-mitochondrial communication. In most cases, the molecular detection of the known defects of mtDNA can be carried out by non-invasive techniques, thus making it an easy and relatively inexpensive procedure in the differential diagnosis of the mitochondrial disorders, a rapidly expanding area of clinical neurology.
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PMID:Mitochondrial diseases. 795 50

The study of diabetic polyneuropathy is complicated by a lack of clear definitions and the absence of a simple reliable test procedure. Recently, a new sensory perception testing device has been introduced for detection of thresholds for electrical stimuli (current perception: CPT) at different frequencies (Neurometer). We compared standardized clinical examination scores with measurements of vibratory perception threshold (VPT) and CPT (foot) and obtained reproducibility figures. Participants in the study were healthy controls (H, n = 33), diabetic patients without clinical signs of neuropathy (DN-, n = 23), diabetics with overt diabetic neuropathy (DN+, n = 22), and patients with a diabetes duration of over 20 years (D20, n = 38). As expected, there were highly significant differences (Wilcoxon) in CPT, VPT and neurological scores between H/DN- and DN+ (p < 0.001), but not between H and DN-. Correlation between CPT and total as well as partial (reflecting small and large fibre functions) neurological examination score were highest at 2000 Hz (r = 0.88); no advantage of lower frequency CPT could be identified. CPT seemed rather insensitive in detecting neuropathy. Correlations between CPT and VPT were only moderate and maximal at 2000 Hz (r = 0.61). Reproducibility of CPT was good at 2000 Hz (coefficient of variation 13.3-20.2%), but moderate to poor at lower frequencies (ranging to 62%). We conclude that CPT and VPT quantitative sensory testing is only of limited value, mainly because of high variability and poor reproducibility.
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PMID:Comparison of clinical examination, current and vibratory perception threshold in diabetic polyneuropathy. 820 23

The reaction of the methyl ester of (R)-norcarnitine with 1-bromo-2-heptadecanone produces (+)-6-[(methoxycarbonyl)methyl]-2-pentadecyl-4,4-dimethylmorpholinium bromide, 3, which hydrolyzes to (+)-6-(carboxylatomethyl)-2-pentadecyl-4,4-dimethylmorpholinium (hemipalmitoylcarnitinium, HPC) upon treatment with aqueous sodium hydroxide. Single-crystal X-ray analyses have confirmed the structures of (+)-HPC and 3. (+)-HPC inhibits carnitine palmitoyltransferase (CPT-I) activity for the forward reaction (palmitoyl-CoA + carnitine-->) in intact mitochondria from rat heart and rat liver. (+)-HPC competitively (versus carnitine) inhibits CPT-I activity in both rat heart and liver mitochondria with Ki = 2.8 +/- 0.5 and 4.2 +/- 0.7 microM, respectively. As one of the strongest specific inhibitors of CPT-I, HPC is a potential therapeutic agent in myocardial ischemia and Type II diabetes.
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PMID:(+)-Hemipalmitoylcarnitinium strongly inhibits carnitine palmitoyltransferase-I in intact mitochondria. 842 95

A typical clinical feature of patients with fasting hyperglycemia in diabetes is well correlated with accelerated hepatic glucose production which is determined by elevated FFA-induced gluconeogenesis. Therefore, to treat fasting hyperglycemia, inhibition of both FFA release and fatty acid oxidation in the liver may be efficient modalities of treatment. (1) Inhibitor of FFA release: a novel selective adenosine A1 agonist, SDZ WAG 994 is a potent inhibitor of adenosine deaminase-induced lipolysis. Twenty-three-week old, male GK rats showing glucose intolerance were treated with WAG 994 (1000 micrograms/kg body weight) for 16 days. Plasma glucose level at 0 time in WAG group was significantly (P < 0.01) less than that of the control. Both plasma FFA and triglyceride concentrations also decreased by 54% and 74%, respectively (vs. control GK rats). (2) Inhibition of hepatic fatty acid oxidation: beta-aminobetaine (emeriamine) is a water-soluble carnitine analog and inhibition of CPT-1 in isolated hepatocytes is 100 times more sensitive than that in isolated cardiocytes and it suppresses both gluconeogenesis and ketogenesis by 60-80%. However, it may be possible that this drug may induce fat deposition in the liver. An inhibitor of elevated fatty acid release from adipose tissue in concomitant with liver-specific and reversible inhibition of fatty acid oxidation may be an effective agent with hypoglycemic and hypolipidemic action for the treatment of diabetes mellitus.
Diabetes Res Clin Pract 1995 Aug
PMID:Rationale and hurdles of inhibitors of hepatic gluconeogenesis in treatment of diabetes mellitus. 852 14

The mRNA level of the catalytic subunit of rat liver glucose-6-phosphatase (Glu-6-Pase) was regulated by hormones commensurate with activity changes in vivo. Insulin exerts a dominant negative effect on the mRNA levels of Glu-6-Pase. Both mRNA levels and activities of the enzyme are low in the fed and refed state where insulin levels are elevated. Insulin administration to diabetic rats also decreases levels of mRNA and Glu-6-Pase activity. Insulin at a concentration of 1 nmol/l completely overcomes the stimulatory effect of glucocorticoids on Glu-6-Pase message levels in FAO hepatoma cells. The stimulatory response to glucocorticoid in FAO cells is biphasic, with maxima seen at 3 and 18 h after hormone addition (respectively 1.6- and 3.3-fold). 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) causes a fourfold increase in Glu-6-Pase mRNA at 3 h in FAO cells. The gene of rat liver Glu-6-Pase is 13 kilobases in length and comprised of 5 exons. The exon-intron structure is completely conserved when compared with the mouse and human genes. A 0.5-kb 3'-untranslated region, which is present in rat and mouse liver Glu-6-Pase cDNA, is absent in the Glu-6-Pase gene reported here, indicating the possible duplication of either the terminal fifth exon or the entire gene. The promoter region contains a consensus core CCAAT element at position -207 and a TATAAA at position -31. Several possible response elements have been identified in the 5'-flanking region (from a HindIII site at position -1641). A consensus glucocorticoid response element is located at base pair -1552, a 9/10 match of the insulin response sequence is located at position -1449, and a 7/8 match of the cAMP response element is located at position -164.
Diabetes 1996 Nov
PMID:Regulation of rat liver glucose-6-phosphatase gene expression in different nutritional and hormonal states: gene structure and 5'-flanking sequence. 886 62

Much biochemical evidence has implicated rat adipocyte CD36 (FAT) in membrane binding and transport of long-chain fatty acids (FA). Expression of the mRNA favored tissues with active FA metabolism and was upregulated in vivo with diabetes and with high fat feeding. In culture, CD36 mRNA was a strong marker of preadipocyte differentiation and was modulated by the same factors effective on mRNAs coding for other proteins involved in FA metabolism. In preadipocytes, long-chain FA or 2-bromopalmitate but not short-chain FA strongly induced CD36 mRNA within 8 h to an optimum within 24 h. Removal of the FA resulted in a decay of CD36 mRNA with a half life of about 12 h. In differentiated adipocytes, levels of CD36 mRNA were downregulated by the 3': 5'-cyclic adenosine monophosphate, cAMP, analog, 8-(4-chlorophenylthio) adenosine, 8-CPT, at concentrations of 1-100 microM. The effect, observed within 6 h, was optimal after 18 h and independent of the action of 8-CPT to mobilize FA. Regulation of CD36 expression by factors effective on expression of other proteins implicated in FA metabolism is consistent with its role in membrane FA transport.
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PMID:Regulation of FAT/CD36 gene expression: further evidence in support of a role of the protein in fatty acid binding/transport. 925 Jun 3

As part of an ongoing search for susceptibility genes in obese families, we performed linkage analyses in 101 French families between qualitative and quantitative traits related to morbid obesity and polymorphisms located in or near 15 candidate genes whose products are involved in body weight regulation. These included cholecystokinin A and B receptors (CCK-AR and CCK-BR), glucagon-like peptide 1 receptor (GLP-1R), the LIM/homeodomain islet-1 gene (Isl-1), the caudal-type homeodomain 3 (CDX-3), the uncoupling protein 1 (UCP-1), the beta3-adrenoceptor (beta3-AR), the fatty acid-binding protein 2 (FABP-2), the hormone-sensitive lipase (HSL), the lipoprotein lipase (LPL), the apoprotein-C2 (apo-C2), the insulin receptor substrate-1 (IRS-1), the peroxisome proliferator-activated receptor-gamma (PPAR-gamma), tumor necrosis factor-alpha (TNF-alpha), and the liver carnitine palmitoyltransferase-1 (CPT-1). Phenotypes related to obesity such as BMI, adult life body weight gain, fasting leptin, insulin, fasting glycerol, and free fatty acids were used for nonparametric sib-pair analyses. A weak indication for linkage was obtained between the Isl-1 locus and obesity status defined by a z score over one SD of BMI (n = 226 sib pairs, pi = 0.54 +/- 0.02, P = 0.03). Moreover, a suggestive indication for linkage was found between the Isl-1 locus and BMI and leptin values (P = 0.001 and 0.0003, respectively) and leptin adjusted for BMI (P = 0.0001). Multipoint analyses for leptin trait with Isl-1 and two flanking markers (D5S418 and D5S407) showed that the logarithm of odds (LOD) score is 1.73, coinciding with the Isl-1 locus. Although marginally positive indications for linkage in subgroups of families were found with IRS-1, CPT-1, and HSL loci, our data suggested that these genes are not major contributors to obesity. Whether an obesity susceptibility gene (Isl-1 itself or another nearby gene) lies on chromosome 5q should be determined by further analyses.
Diabetes 1999 Feb
PMID:A sib-pair analysis study of 15 candidate genes in French families with morbid obesity: indication for linkage with islet 1 locus on chromosome 5q. 1033 20

In type 2 diabetes mellitus, insulin secretory deficiency is an important process linking asymptomatic insulin resistance and diabetes. Fatty acids could play a role in the reduction of beta cell insulin secretion. On a short term basis (< 24 h), fatty acids stimulate glucose-dependent insulin secretion through an increase of ATP availability (due to acyl-CoA mitochondrial oxidation) and an extramitochondrial diacylglycerol and inositol tri phosphate (IP3) production (which stimulate insulin-containing granule exocytosis). Such effects were observed in human both in vitro and in vivo. By contrast, a chronic exposure (> 24 h) of beta cells to fatty acids leads to a reduction in glucose-dependent insulin secretion. Current explanation relies in the effect of fatty acids on beta cell gene expression through PPARs (peroxysome proliferator activated receptor). Thus, in rodents, fatty acids can increase the expression of carmitine palmitoyl transferase gene (CPT-1, the key enzyme involved in fatty acid internalization in mitochondria) while reducing the gene expression of acetyl carboxylase (this enzyme synthesis malonyl CoA, which inhibits fatty acid oxidation). Thus, a chronic exposure to fatty acids will preferentially distribute these nutrients towards mitochondria (as malonyl CoA is reduced and CPT-1 is increased), which in turn reduces their extramitochondrial metabolism as well as IP3 production that is needed for secretory granule exocytosis. Finally, in Zucker Fatty rat, diabetes is associated with a triglyceride accumulation in beta cells. This is correlated with a reduction in insulin secretion and an increase in cellular apoptosis phenomena. Thiazolidinediones prevent intracellular lipid accumulation and delay diabetes. The prevention of lipotoxicity could represent a new therapeutic strategy to preserve insulin secretion in type 2 diabetic patients.
Diabetes Metab 2000 Jun
PMID:[Fatty acids and beta cells]. 1094 43

Carnitine palmitoyltransferase I (CPT-I) catalyzes the transfer of long chain fatty acyl groups from CoA to carnitine for translocation across the mitochondrial inner membrane. CPT-Ialpha is a key regulatory enzyme in the oxidation of fatty acids in the liver. CPT-Ialpha is expressed in all tissues except skeletal muscle and adipose tissue, which express CPT-Ibeta. Expression of CPT-Ialpha mRNA and enzyme activity are elevated in the liver in hyperthyroidism, fasting, and diabetes. CPT-Ialpha mRNA abundance is increased 40-fold in the liver of hyperthyroid compared with hypothyroid rats. Here, we examine the mechanisms by which thyroid hormone (T3) stimulates CPT-Ialpha gene expression. Four potential T3 response elements (TRE), which contain direct repeats separated by four nucleotides, are located 3000-4000 base pairs 5' to the start site of transcription in the CPT-Ialpha gene. However, only one of these elements functions as a TRE. This TRE binds the T3 receptor as well as other nuclear proteins. Surprisingly, the first intron of the CPT-Ialpha gene is required for the T3 induction of CPT-Ialpha expression, but this region of the gene does not contain a TRE. In addition, we show that CPT-Ialpha is induced by T3 in cell lines of hepatic origin but not in nonhepatic cell lines.
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PMID:Thyroid hormone regulates carnitine palmitoyltransferase Ialpha gene expression through elements in the promoter and first intron. 1095 41


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