Haptoglobin binds the antiatherogenic protein apolipoprotein E - impairment of apolipoprotein E stimulation of both lecithin:cholesterol acyltransferase activity and cholesterol uptake by hepatocytes.

Full Abstract

Haptoglobin (Hpt) binds apolipoprotein A-I (ApoA-I), and impairs its stimulation of lecithin:cholesterol acyltransferase (LCAT). LCAT plays a major role in reverse cholesterol transport (RCT). Apolipoprotein E (ApoE), like ApoA-I, promotes different steps of RCT, including LCAT stimulation. ApoE contains amino acid sequences that are homologous with the ApoA-I region bound by Hpt and are involved in the interaction with LCAT. Therefore, Hpt was expected to also bind ApoE, and inhibit the ApoE stimulatory effect on LCAT. Western blotting and ELISA experiments demonstrated that the Hpt beta-subunit binds ApoE. The affinity of Hpt for ApoE was higher than that for ApoA-I. High ratios of Hpt with either apolipoprotein, such as those associated with the acute phase of inflammation, inhibited, in vitro, the stimulatory effect of ApoE on the cholesterol esterification activity of LCAT. Hpt also impaired human hepatoblastoma-derived cell uptake of [(3)H]cholesterol from proteoliposomes containing ApoE or ApoA-I. We suggest that the interaction between Hpt and ApoE represents a mechanism by which inflammation affects atherosclerosis progression. Hpt might influence ApoE function in processes other than RCT.

Author information

Author/s: Cigliano, Luisa (L); Pugliese, Carmela R (CR); Spagnuolo, Maria S (MS); Palumbo, Rosanna (R); Abrescia, Paolo (P);

Affiliation: Dipartimento delle Scienze Biologiche, Università di Napoli Federico II, Italy.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: The FEBS journal (FEBS J), published in England. (Language: eng)

Reference: 2009-Nov; vol 276 (issue 21) : pp 6158-71

Dates: Created 2009/10/14; Completed 2009/10/28;

PMID: 19758344, status: MEDLINE (last retrieval date: 10/28/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article
(including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Apolipoprotein A-I - metabolism
Apolipoproteins E - physiology
Atherosclerosis - prevention & control
Binding, Competitive
Cell Line, Tumor
Cholesterol - metabolism
Haptoglobins - metabolism

Haptoglobins - metabolism
Hemoglobins - metabolism
Hepatocytes - metabolism
Humans
Lipoproteins, LDL - metabolism
Lipoproteins, VLDL - metabolism
Phosphatidylcholine-Sterol O-Acyltransferase - metabolism

Associated Chemicals: Apolipoprotein A-I (0) ; Apolipoproteins E (0) ; Haptoglobins (0) ; Hemoglobins (0) ; Lipoproteins, LDL (0) ; Lipoproteins, VLDL (0) ; Cholesterol (57-88-5) ; Phosphatidylcholine-Sterol O-Acyltransferase (EC 2.3.1.43)

These are the highest related articles currently in the database: