Role Of apoE Research Articles

Abnormal low density lipoprotein metabolism in apolipoprotein E deficiency.

Apolipoprotein(apo) E deficiency is an inherited disease characterized by type III hyperlipoproteinemia and less than 1% normal plasma apoE concentration. The role of apoE in LDL metabolism was investigated by quantitating the metabolism of radiolabeled normal and apoE-deficient LDL in both normal and apoE-deficient subjects. ApoE deficiency resulted in an accumulation of plasma IDL, and a decreased synthesis of LDL consistent with a block in the conversion of IDL to LDL. The LDL isolated from the apoE-deficient patient was similar to normal LDL in hydrated density, size, and composition. However, the apoE-deficient LDL was kinetically abnormal with delayed catabolism in both normal subjects and the apoE-deficient patient. In addition, the catabolism of normal LDL in the apoE-deficient subject was increased. These results were interpreted as indicating that apoE is necessary for the conversion of IDL to LDL and the formation of kinetically normal LDL. The rapid catabolism of normal LDL in the apoE-deficient patient suggests an up-regulation of the hepatic LDL receptor pathway. Based on these results, apoE is proposed to play an important role in the conversion of IDL to LDL, the formation of kinetically normal LDL, and the regulation of LDL receptor function.

Apolipoprotein E and cholesterol metabolism.

The role of apo-E in mediating lipoprotein interaction with specific receptors has been established. Through the use of selective chemical modification of specific amino acid residues of certain lipoproteins, we have gained insight into the importance of the lysine and arginine residues in this process. This understanding has been expanded by structure-function studies of mutant forms of apo-E. These studies have revealed important information concerning the genetic heterogeneity of the apo-E isoforms, focusing attention on the importance of a specific region of apo-E in the binding process.

A Role of ApoA-1 in LCAT Reaction

A Role of ApoA-1 in LCAT Reaction

Erythrocyte 2,3-diphosphoglycerate in diabetes and renal disease.

Background: Chronic alcohol consumption down-regulates the expression of sialytransferase genes resulting in impaired sialylation of apolipoprotein E (apoE) and decreased association with HDL. There are a limited number of studies with contradictory data on the effect of alcohol dependence on human plasma apoE. The aim of the present work is to determine and compare the levels of apoE in relation to the other lipoproteins in alcohol-dependent individuals in order to evaluate the possible role of apoE in lipoprotein metabolism in conditions of severe alcohol dependence. Patients and Methods: The sample of our study comprised 43 DSM-IV diagnosed alcohol-dependent/abusing subjects (33 males and 10 females), treated on an inpatient basis according to a standard detoxification protocol, and 27 healthy people (9 males and 18 females, as a control group). Serum concentration of hepatic enzymes (AST, ALT, γGT), as well as measures of cholesterol and lipoproteins were obtained at baseline and at discharge after a detoxification period of 4-5 weeks. Results: Upon admission, all alcohol-dependent individuals had significantly higher hepatic enzyme levels, apoE and HDL values compared to controls. After completion of alcohol detoxification, all the above parameters returned to normal levels. Additionally, a significant correlation was observed between alcohol consumption during the previous year of alcohol abuse and the apoE values both upon admission to and on discharge from the detoxification program. Conclusion: The statistical correlation between apoE on admission and discharge with alcohol consumption during the previous year suggests that apoE is dependent on alcohol consumption and can serve as a sensitive marker of severe alcohol abuse.