Ανάλυση του μονοπατιού βιογένεσης της HDL με μεταλλαξιογένεση της απολιποπρωτεΐνης Α-Ι

Analysis of the pathway of biogenesis of HDL by mutations of apolipoprotein A-I

Ανάλυση του μονοπατιού βιογένεσης της HDL με μεταλλαξιογένεση της απολιποπρωτεΐνης Α-Ι

Kateifides, Andreas

Κατεϊφίδης, Ανδρέας

PhD Thesis

2011

Apolipoprotein A-I is a key protein for the biogenesis of High Density Lipoproteins and protects from atherosclerosis. Mutations in apoA-I gene are associated with low HDL levels and predisposition to atherosclerosis. The purpose of the present thesis was to explore the structure-function relationship in human apoA-I and the role of specific amino acid residues in HDL biogenesis and maturation. The thesis is organized in two parts. Part I: Alteration of Negatively Charged Residues in the 89 to 99 Domain of ApoA-I Affects Lipid Homeostasis and the Maturation of HDL (J Lipid Res. 2011 Jul;52(7):1363-72). Adenovirus-mediated gene transfer in apoA-I-/- mice showed that an apoA-I[D89A/E91A/E92A] mutant increased plasma cholesterol and caused severe hypertriglyceridemia. HDL levels were reduced and approximately 40% of the apoA-I was distributed in VLDL/IDL. The HDL consisted of mostly spherical and few discoidal particles and contained preβ1 and α4-HDL subpopulations. The mutant protein had increased affinity for triglyceride-rich emulsions. The lipid, lipoprotein and HDL profiles of the apoA-I[K94A/K96A] mutant were similar, but not identical, to those of wild type apoA-I. Co-expression of apoA-I[D89A/E91A/E92A] and human lipoprotein lipase abolished hypertriglyceridemia, restored in part the α1,2,3,4 HDL subpopulations, redistributed apoA-I in the HDL2/HDL3 regions, but did not prevent the formation of discoidal HDL particles. We conclude that residues D89, E91 and E92 of apoA-I are important for plasma cholesterol and triglyceride homeostasis as well as for the maturation of HDL. The present and two previous studies raise the possibility that xvii mutations in apoA-I in the general population may alter the functions of apoA-I and HDL and contribute to hypertriglyceridemia. Part II: Contribution of the residues 218 to 226 of apoA-I in the biogenesis of HDL. Adenovirus mediated gene transfer of an apoA-I [L218A/L219A/V221A/L222A] mutant in apoA-I-/- mice resulted in decreased plasma cholesterol and apoA-I levels to approximately 10 % as compared to WT control and generated preβ and α4-HDL particles. The HDL cholesterol peak of the mutant protein was greatly diminished. When expressed in double deficient mice for apoA-I and apoE the apoAI[ L218A/L219A/V221A/L222A] mutant failed to form HDL particles as determined by 2D gel electrophoresis and electron microscopy. The apoA-I[E223A/K226A] mutant had similar plasma apoA-I levels and similar but not identical lipid and lipoprotein profiles with WT apoA-I. Overall the findings suggest that crucial changes in the C-terminal 218- 222 hydrophobic residues of apoA-I impair seriously the functional interactions of apoAI with ABCA1 and/or LCAT and inhibit biogenesis of HDL. In the context of this thesis we also investigated, in collaboration with other groups, the role of apoA-I C-terminus in endothelial transcytosis of HDL (J Biol Chem. 2011 Mar 11;286(10):7744-54), the bactericidal activity of apoA-I against Yersinia enterocolitica serotypre O:3 (manuscript in preparation) and apoA-I mutations in patients with increased risk of ischaemic heart disease and total mortality in the population of Copenhagen (J Intern Med. 2011 Mar 28. doi: 10.1111 in press)

Ιατρική και Επιστήμες Υγείας ➨ Βασική Ιατρική

Μεταφορά γονιδίων

Basic Medicine

HDL ( High Density Lipoprotein )

Mutagenesis

Gene transfer

Medical and Health Sciences

Απολιποπρωτείνη Α-Ι

Apolipoprotein A-I

Βασική Ιατρική

Μεταλλαξογένεση

Ιατρική και Επιστήμες Υγείας

English

University of Crete (UOC)

Πανεπιστήμιο Κρήτης

Πανεπιστήμιο Κρήτης. Σχολή Επιστημών Υγείας. Τμήμα Ιατρικής. Τομέας Βασικών Επιστημών. Εργαστήριο Βιοχημείας

National Documentation Centre (EKT)

National Archive of PhD Theses

Συλλογή ΕΑΔΔ