ApoA-I mutations, L202P and K131del, in HDL from heterozygotes with low HDL-C

PurposeMutations in apolipoprotein A-I (apoA-I) may affect plasma high-density lipoprotein (HDL) cholesterol levels and the risk for cardiovascular disease but little is known about the presence and effects of circulating apoA-I variants. This study investigates whether the apoA-I mutations, apoA-I-L202P and apoA-I-K131del, are present on plasma HDL particles derived from heterozygote carriers and whether this is associated to changes in HDL protein composition.

Experimental designPlasma HDL of heterozygotes for either apoA-I-L202P or apoA-I-K131del and family controls was isolated using ultracentrifugation. HDL proteins were separated by 2DE and analyzed by MS.

ResultsApoA-I peptides containing apoA-I-L202P or apoA-I-K131del were identified in HDL from heterozygotes. The apoA-I-L202P mutant peptide was less abundant than wild-type peptide while the apoA-I-K131del mutant peptide was more abundant than wild-type peptide in the heterozygotes. Two-dimensional gel electrophoresis analyses indicated that, compared to controls, HDL in apoA-I-L202P carriers contained less apoE and more zinc--2-glycoprotein while HDL from the apoA-I-K131del heterozygotes contained more alpha-1-antitrypsin and transthyretin.

Conclusions and clinical relevanceBoth apoA-I-L202P and apoA-I-K131del were identified in HDL. In heterozygotes, these mutations have markedly differential effects on the concentration of wild-type apoA-I in the circulation, as well as the HDL proteome, both of which might affect the clinical phenotype encountered in the heterozygous carriers.