Structure–function analysis of naturally occurring apolipoprotein A-I L144R, A164S and L178P mutants provides insight on their role on HDL levels and cardiovascular risk

• Published in: Cellular and molecular life sciences : CMLS Vol. 78; no. 4; pp. 1523 - 1544
• Main Authors: Gkolfinopoulou, Christina, Soukou, Faye, Dafnis, Ioannis, Kellici, Tahsin F., Sanoudou, Despina, Mavromoustakos, Thomas, Stratikos, Efstratios, Chroni, Angeliki
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.02.2021; Springer Nature B.V
• Subjects: ABCA1 protein; AKT protein; Apolipoprotein A; Apolipoprotein A-I; Apolipoprotein A-I - genetics; Apolipoprotein A-I - metabolism; Apolipoprotein A-I - ultrastructure; Apolipoproteins; ATP Binding Cassette Transporter, Subfamily G, Member 1 - genetics; ATP Binding Cassette Transporter, Subfamily G, Member 1 - metabolism; ATP-binding protein; Biochemistry; Biomedical and Life Sciences; Biomedicine; Cardiovascular diseases; Cardiovascular Diseases - genetics; Cardiovascular Diseases - pathology; Cell adhesion & migration; Cell Biology; Cell migration; cell movement; Cell Movement - genetics; Cholesterol; Cholesterol, HDL - genetics; Cholesterol, HDL - metabolism; Cholesterol, HDL - ultrastructure; Destabilization; Efflux; Endothelial cells; Endothelial Cells - metabolism; Endothelial Cells - pathology; Free form; Function analysis; Health risks; Heart Disease Risk Factors; High density lipoprotein; high density lipoprotein cholesterol; Humans; Ketocholesterols - genetics; Ketocholesterols - metabolism; Kinases; Life Sciences; Lipids; Lipoproteins, HDL - genetics; Lipoproteins, HDL - metabolism; Lipoproteins, HDL - ultrastructure; Liquid oxygen; LOX-1 protein; mortality; Mutant Proteins - genetics; Mutant Proteins - metabolism; Mutant Proteins - ultrastructure; Mutants; Mutation; Mutation - genetics; Original; Original Article; Phenotypes; Risk; Scavenger Receptors, Class E - genetics; Scavenger Receptors, Class E - metabolism; Structural integrity; Structure-Activity Relationship; Structure-function relationships; Thermodynamics; High-density lipoprotein; ApoA-I/HDL functional properties; Coronary artery disease; Protein conformation; Apolipoprotein A-I; Mutant
• DOI: 10.1007/s00018-020-03583-y
• ISSN: 1420-682X; 1420-9071

Naturally occurring point mutations in apolipoprotein A-I (apoA-I), the major protein component of high-density lipoprotein (HDL), may affect plasma HDL-cholesterol levels and cardiovascular risk. Here, we evaluated the effect of human apoA-I mutations L144R (associated with low HDL-cholesterol), L178P (associated with low HDL-cholesterol and increased cardiovascular risk) and A164S (associated with increased cardiovascular risk and mortality without low HDL-cholesterol) on the structural integrity and functions of lipid-free and lipoprotein-associated apoA-I in an effort to explain the phenotypes of subjects carrying these mutations. All three mutants, in lipid-free form, presented structural and thermodynamic aberrations, with apoA-I[L178P] presenting the greatest thermodynamic destabilization. Additionally, apoA-I[L178P] displayed reduced ABCA1-mediated cholesterol efflux capacity. When in reconstituted HDL (rHDL), apoA-I[L144R] and apoA-I[L178P] were more thermodynamically destabilized compared to wild-type apoA-I, both displayed reduced SR-BI-mediated cholesterol efflux capacity and apoA-I[L144R] showed severe LCAT activation defect. ApoA-I[A164S] was thermodynamically unaffected when in rHDL, but exhibited a series of functional defects. Specifically, it had reduced ABCG1-mediated cholesterol and 7-ketocholesterol efflux capacity, failed to reduce ROS formation in endothelial cells and had reduced capacity to induce endothelial cell migration. Mechanistically, the latter was due to decreased capacity of rHDL-apoA-I[A164S] to activate Akt kinase possibly by interacting with endothelial LOX-1 receptor. The impaired capacity of rHDL-apoA-I[A164S] to preserve endothelial function may be related to the increased cardiovascular risk for this mutation. Overall, our structure–function analysis of L144R, A164S and L178P apoA-I mutants provides insights on how HDL-cholesterol levels and/or atheroprotective properties of apoA-I/HDL are impaired in carriers of these mutations.