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

beta-Oxidation of long-chain fatty acids increases many-fold in atherosclerotic aortas; this may be due to an increase in the activity of the mitochondrial enzyme hexadecanoyl-CoA: carnitine O-hexadecanoyltransferase EC 2.3.1.23 (trivial name: carnitine palmitoyltransferase, CPT). To investigate this possibility, an assay for arterial CPT was developed and used to measure CPT activity in mitochondrial fractions isolated from aortas of rabbits fed high-fat (HF) or high-fat plus cholesterol (HFC) supplemented diets. The arterial CPT assay was linear with respect to mitochondrial protein between 0.03 and 0.30 mg and assay time between 3 and 12 min. Maximum CPT activity was observed at concentrations of palmitoyl-CoA between 5 and 25 micron, higher concentrations of palmitoyl-CoA inhibited CPT activity. CPT activity was measured in mitochondrial fractions isolated from aortas of rabbits fed the HFC-supplemented diet for up to 48 days. No visible lesions were observed in aortas of rabbits fed HFC-diet for 3,9, or 21 days, however, by 48 days atheromatous lesions covered in excess of 60% of the intimal surface of the aorta. No lesions were visually observed in aortas of rabbits receiving the HF-diet. Despite the development of gross atherosclerotic lesions, there were no changes in CPT activity observed that could account for a dramatic increase in fatty acid oxidation. It is concluded that the increase in beta-oxidation of long-chain fatty acids in atherosclerosis is not attributable to an increase in CPT activity.
Atherosclerosis 1979 Sep
PMID:Carnitine palmitoyltransferase activity in mitochondrial fractions isolated from aortas of rabbits fed cholesterol-supplemented diets. 49 40

Lecithin:cholesterol acyltransferase (LCAT) and lysolecithin acyltransferase (LAT) are two activities carried out by the same plasma enzyme, but require different apoprotein activators. The LCAT reaction takes place primarily on high density lipoproteins (HDL) and is activated by serum albumin, whereas LAT takes place on low density lipoproteins (LDL) and is inhibited by albumin. In nephrotic syndrome (NS), the levels of serum albumin are reduced, whereas the LDL levels are increased, and therefore, the ratio of LAT/LCAT activities should be increased. To test this hypothesis, we estimated the lipid levels and the two enzyme activities in experimental NS induced in rats by the injection of anti-Fx1A antibody (passive Heymann nephritis). As found in other nephrotic conditions, the plasma lipid levels rose progressively as the proteinuria increased and the serum albumin concentration declined. In addition, the ratio of LAT/LCAT activities increased by about fourfold after nine days of induction of nephritis. The LCAT activity correlated positively and the LAT activity negatively with serum albumin levels. The esterified cholesterol correlated positively with LCAT activity in normal rats but negatively in nephrotic animals, indicating that most of the cholesteryl esters in NS may be non-LCAT derived. The free cholesterol/lecithin ratio, a known risk factor for atherosclerosis, increased significantly in nephrotic rats. Furthermore, since the increase in the LAT activity produces more disaturated lecithins, another putative risk factor, the cumulative risk of coronary heart disease may be increased in long-term NS.
 ...
PMID:Plasma lipids and acyltransferase activities in experimental nephrotic syndrome. 277 94

The effect of various chemical and enzymatic modifications of low density lipoprotein (LDL) on its ability to activate the isolated human plasma lysolecithin acyltransferase (LAT) was studied. Removal of all lipids from LDL resulted in the complete loss of LAT activation. Removal of only neutral lipids by extraction with heptane retained up to 50% of the original activity, which was not increased further by reconstitution of the LDL with the extracted lipids. Hydrolysis of the diacylphosphoglycerides of the LDL with phospholipases resulted in complete loss of LAT activation which was partially restored by the addition of egg lecithin. Hydrolysis of more than 4% of LDL protein by trypsin led to a linear decrease in activity with complete loss of activity occurring when about 25% of the LDL protein is hydrolyzed. Modification of the arginine groups of LDL reversibly inhibited the activation of LAT. Modification of lysine residues of LDL by acetylation, acetoacetylation or succinylation also abolished its ability to activate lysolecithin acylation.
Atherosclerosis 1985 Jan
PMID:Role of low density lipoprotein in the activation of plasma lysolecithin acyltransferase activity. Effect of chemical and enzymatic modifications of the lipoprotein on enzyme activity. 392 84

Because lecithin-cholesterol acyltransferase (LCAT) has been shown to carry out acylation of lysolecithin as well as hydrolysis of lecithin in addition to an esterification of cholesterol, the cofactor requirements of the three reactions catalyzed by the enzyme were studied. The purified enzyme required apolipoprotein A-I (apo A-I) for both the phospholipase A2 activity (release of free fatty acids from lecithin) and cholesterol esterification, whereas, low density lipoprotein (LDL) was required for the acylation of lysolecithin. Apo A-I and lecithin liposomes could not substitute for LDL for the activation of lysolecithin acyltransferase activity. Removal of apo A-I from the LDL preparation by affinity chromatography did not affect the activation of lysolecithin acylation, indicating that the contaminating apo A-I is not responsible for the activation. LDL facilitates cholesterol esterification in presence of labelled lecithin liposomes by providing the unesterified cholesterol. Removal of contaminating apo A-I, however, abolishes this LCAT activity which could be restored by addition of pure apo A-I. Lysolecithin inhibits both phospholipase A2 and LCAT activities, but LDL appeared to attenuate the effects of lysolecithin, in addition to stimulating the acylation of lysolecithin. These results show that apo A-I is not obligatory for all the reactions carried out by the enzyme, and that LDL plays an important role in the regulation of the hydrolysis and acylation reaction carried out by the enzyme.
Atherosclerosis 1982 Nov
PMID:Studies on the cofactor requirement for the acylation and hydrolysis reactions catalyzed by purified lecithin-cholesterol acyltransferase. Effect of low density lipoproteins and apolipoprotein A-i. 715 94

To determine the effects of the nephrotic syndrome (NS) on atherogenic risk, we studied the lipoprotein composition and the activities of lecithin-cholesterol acyltransferase (LCAT), lysolecithin acyltransferase (LAT), and cholesteryl ester transfer (CET) in the plasma of 11 NS patients and 10 control subjects. NS plasma had lower ratios of high-density lipoprotein (HDL) to low-density lipoprotein (LDL) and HDL2/HDL3 and an elevated free cholesterol (FC) to phosphatidyl choline (PC) ratio (1.09 +/- 0.27 in NS and 0.72 +/- 0.21 in controls, P < .02), all of which indicate an increased atherogenic potential. LCAT activity was normal in NS plasma when assayed with an exogenous substrate, but was 40% lower than in control plasma when assayed with the endogenous substrates. However, in vitro addition of serum albumin to NS plasma failed to normalize the LCAT activity. The LAT reaction, which is catalyzed by LCAT protein in the presence of LDL, was 60% to 80% higher in NS plasma, and consequently the ratio of LAT/LCAT activities was increased twofold. CET activity was significantly increased (+160% of control), and this abnormality was attributable to changes in both the acceptor (very-low-density lipoprotein [VLDL] + LDL) and donor (HDL) lipoproteins and possibly in CET protein. These results suggest that the NS may increase the risk of atherosclerosis not only by adversely affecting the concentrations of lipoproteins, but also by altering their composition and function.
 ...
PMID:Abnormal acyltransferase activities and accelerated cholesteryl ester transfer in patients with nephrotic syndrome. 808 87

Free arachidonic acid (AA) is an important precursor of lipid mediators such as leukotrienes and prostaglandins that induces inflammation and is associated with atherosclerosis progression. Recent studies have shown that lysophosphatidylcholine acyltransferase-3 (LPCAT3) converts lysophosphatidylcholine (LPC) and free AA into phosphatidylcholine (PC)-containing AA (arachidonyl-PC) and thereby can regulate intracellular free-AA levels. However, the association between LPCAT3 and atherosclerosis remains to be established. In this study, we analyzed human and mouse atherosclerotic tissues to gain insight into the arachidonyl-PC metabolism involving LPCAT3 using imaging mass spectrometry. The data revealed a complementary distribution of arachidonyl-PC and LPC in human atherosclerotic tissues with arachidonyl-PC decreasing and LPC increasing as atherosclerosis progressed. Furthermore, we found a homologous distribution of LPCAT3 expression and arachidonyl-PC based on atherosclerotic progression. In contrast, in ApoE-deficient mice, atherosclerosis increased both arachidonyl-PC accumulation and LPCAT3 expression. Taken together, these findings suggest that the regulation of LPCAT3 expression might be associated with atherosclerotic progression in humans.
 ...
PMID:Lysophosphatidylcholine Acyltransferase-3 Expression Is Associated with Atherosclerosis Progression. 2868 45

Phospholipids are major constituents of biological membranes. The fatty acyl chain composition of phospholipids determines the biophysical properties of membranes and thereby affects their impact on biological processes. The composition of fatty acyl chains is also actively regulated through a deacylation and reacylation pathway called Lands' cycle. Recent studies of mouse genetic models have demonstrated that lysophosphatidylcholine acyltransferases (LPCATs), which catalyze the incorporation of fatty acyl chains into the sn-2 site of phosphatidylcholine, play important roles in pathophysiology. Two LPCAT family members, LPCAT1 and LPCAT3, have been particularly well studied. LPCAT1 is crucial for proper lung function due to its role in pulmonary surfactant biosynthesis. LPCAT3 maintains systemic lipid homeostasis by regulating lipid absorption in intestine, lipoprotein secretion, and de novo lipogenesis in liver. Mounting evidence also suggests that changes in LPCAT activity may be potentially involved in pathological conditions, including nonalcoholic fatty liver disease, atherosclerosis, viral infections, and cancer. Pharmacological manipulation of LPCAT activity and membrane phospholipid composition may provide new therapeutic options for these conditions.
 ...
PMID:Phospholipid Remodeling in Physiology and Disease. 3037 16