title: Significance of the hydrophobic residues 225-230 of apoA-I for the biogenesis of HDL.
abstract: We studied the significance of four hydrophobic residues within the 225-230 region of apoA-I on its structure and functions and their contribution to the biogenesis of HDL. Adenovirus-mediated gene transfer of an apoA-I[F225A/V227A/F229A/L230A] mutant in apoA-I⁻/⁻ mice decreased plasma cholesterol, HDL cholesterol, and apoA-I levels. When expressed in apoA-I⁻/⁻ × apoE⁻/⁻ mice, approximately 40% of the mutant apoA-I as well as mouse apoA-IV and apoB-48 appeared in the VLDL/IDL/LDL. In both mouse models, the apoA-I mutant generated small spherical particles of pre-β- and α4-HDL mobility. Coexpression of the apoA-I mutant and LCAT increased and shifted the-HDL cholesterol peak toward lower densities, created normal αHDL subpopulations, and generated spherical-HDL particles. Biophysical analyses suggested that the apoA-I[225-230] mutations led to a more compact folding that may limit the conformational flexibility of the protein. The mutations also reduced the ability of apoA-I to promote ABCA1-mediated cholesterol efflux and to activate LCAT to 31% and 66%, respectively, of the WT control. Overall, the apoA-I[225-230] mutations inhibited the biogenesis of-HDL and led to the accumulation of immature pre-β- and α4-HDL particles, a phenotype that could be corrected by administration of LCAT.
authors.affiliation: Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Fotakis
authors.forename: Ioanna
authors.initials: I
authors.lastname: Tiniakou
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Kateifides
authors.forename: Christina
authors.initials: C
authors.lastname: Gkolfinopoulou
authors.forename: Angeliki
authors.initials: A
authors.lastname: Chroni
authors.forename: Efstratios
authors.initials: E
authors.lastname: Stratikos
authors.forename: Vassilis I
authors.initials: VI
authors.lastname: Zannis
authors.forename: Dimitris
authors.initials: D
authors.lastname: Kardassis
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D016632:Apolipoprotein A-I / Q000097:blood / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D055598:Chemical Phenomena; D057809:HEK293 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008075:Lipoproteins, HDL / Q000096:biosynthesis*; D051379:Mice; D009154:Mutation
chemical_list: D016632:Apolipoprotein A-I; D008075:Lipoproteins, HDL
keywords: apolipoprotein A-I mutations; dyslipidemia; high density lipoprotein biogenesis; pre-β- and α-HDL particles