ABCMdb

PMID: 17303779

Kiss RS, Kavaslar N, Okuhira K, Freeman MW, Walter S, Milne RW, McPherson R, Marcel YL
Genetic etiology of isolated low HDL syndrome: incidence and heterogeneity of efflux defects.
Arterioscler Thromb Vasc Biol. 2007 May;27(5):1139-45. Epub 2007 Feb 15., [PubMed]

Sentences

No. Mutations Sentence Comment

38 ABCA1 p.Ser107Tyr In the coding region of PLTP, 2 heterozygous nonsynonymous sequence variants were detected in the low HDL population: S107Y and R459Q. Login to comment 40 ABCA1 p.Ser107Tyr Previous studies demonstrated the importance of the C-terminal region for the functional activity of PLTP and the arginine at position 459 is within the C-terminus.31 PLTP expression in COS7 cells showed that PLTP mutants S107Y and R459Q had normal and 33% decrease in specific activity relative to wild-type protein, respectively (115.3afe;11.2, 66.7afe;6.0 of wild-type activity). Login to comment 41 ABCA1 p.Ser107Tyr These results suggest that S107Y mutant has normal function, but the R459Q mutant had a significant reduction in activity, which could contribute to impaired HDL metabolism. Login to comment 42 ABCA1 p.Trp590Ser ABCA1 p.Ile883Met ABCA1 p.Arg219Lys ABCA1 p.Cys1477Arg ABCA1 p.Ser1731Cys ABCA1 p.Val825Ile ABCA1 p.Val771Met ABCA1 p.Glu1172Asp ABCA1 p.Val399Ala ABCA1 p.Cys1477Phe ABCA1 p.Glu1386Gln ABCA1 p.Pro85Ala ABCA1 p.Arg965Cys ABCA1 p.Asp1706Asn ABCA1 p.Pro85Leu ABCA1 p.His551Asp ABCA1 p.Trp590Leu ABCA1 p.Lys199Phe In ABCA1, a total of 19 nonsynonymous coding sequence variants; some of these we reported previously.22 Of these, 9 sequence variants were common polymorphisms (ie, reported in the literature as common or of similar prevalence in control subjects): P85L, P85A, R219K, V399A, V771M, V825I, I883M, E1172D, R1587K.14,32-35 Another 5 sequence variants, identified here, were previously reported to be disease causing: W590L (reported as W590S)14; C1477F (reported as C1477R)13; S1731C (only found in French-Canadian populations)36; N1800H32; and 1851X.37 Five sequence variants were novel: K199F, H551D, R965C, E1386Q, and D1706N. Login to comment 43 ABCA1 p.Glu1386Gln ABCA1 p.Ser107Tyr In the coding region of PLTP, 2 heterozygous nonsynonymous sequence variants were detected in the low HDL population: S107Y and R459Q. Login to comment 44 ABCA1 p.Asn1800His ABCA1 p.Ser1731Cys ABCA1 p.Cys1477Phe ABCA1 p.Glu1386Gln ABCA1 p.Asp1706Asn ABCA1 p.His551Asp ABCA1 p.Trp590Leu Eight subjects with sequence variants in ABCA1 had defective cholesterol efflux (measured in repeated assays cholesterol-loaded monocyte-derived macrophage [MDMs]), and these ABCA1 sequence variants were tested in an in vitro expression system for cholesterol efflux activity.38 ABCA1 proteins containing the sequence variants W590L, C1477F, D1706N, S1731C, or N1800H were all found to have significantly impaired cholesterol efflux, whereas the H551D and E1386Q variants had very minor, if any, effects on cholesterol transport (Figure 1A). Login to comment 45 ABCA1 p.Ser107Tyr ABCA1 p.His551Asp Previous studies demonstrated the importance of the C-terminal region for the functional activity of PLTP and the arginine at position 459 is within the C-terminus.31 PLTP expression in COS7 cells showed that PLTP mutants S107Y and R459Q had normal and 33% decrease in specific activity relative to wild-type protein, respectively (115.3Ϯ11.2, 66.7Ϯ6.0 of wild-type activity). Login to comment 46 ABCA1 p.Ser107Tyr These results suggest that S107Y mutant has normal function, but the R459Q mutant had a significant reduction in activity, which could contribute to impaired HDL metabolism. Login to comment 47 ABCA1 p.Trp590Ser ABCA1 p.Ile883Met ABCA1 p.Arg219Lys ABCA1 p.Cys1477Arg ABCA1 p.Ser1731Cys ABCA1 p.Val825Ile ABCA1 p.Val771Met ABCA1 p.Glu1172Asp ABCA1 p.Val399Ala ABCA1 p.Cys1477Phe ABCA1 p.Glu1386Gln ABCA1 p.Pro85Ala ABCA1 p.Arg965Cys ABCA1 p.Asp1706Asn ABCA1 p.Pro85Leu ABCA1 p.His551Asp ABCA1 p.Trp590Leu ABCA1 p.Lys199Phe In ABCA1, a total of 19 nonsynonymous coding sequence variants; some of these we reported previously.22 Of these, 9 sequence variants were common polymorphisms (ie, reported in the literature as common or of similar prevalence in control subjects): P85L, P85A, R219K, V399A, V771M, V825I, I883M, E1172D, R1587K.14,32-35 Another 5 sequence variants, identified here, were previously reported to be disease causing: W590L (reported as W590S)14; C1477F (reported as C1477R)13; S1731C (only found in French-Canadian populations)36; N1800H32; and 1851X.37 Five sequence variants were novel: K199F, H551D, R965C, E1386Q, and D1706N. Login to comment 48 ABCA1 p.Glu1386Gln Each subject was heterozygous for their respective coding sequence change, with the exception of 1 subject homozygous for the E1386Q variant. Login to comment 49 ABCA1 p.Asn1800His ABCA1 p.Ser1731Cys ABCA1 p.Cys1477Phe ABCA1 p.Glu1386Gln ABCA1 p.Asp1706Asn ABCA1 p.His551Asp ABCA1 p.Trp590Leu Eight subjects with sequence variants in ABCA1 had defective cholesterol efflux (measured in repeated assays cholesterol-loaded monocyte-derived macrophage [MDMs]), and these ABCA1 sequence variants were tested in an in vitro expression system for cholesterol efflux activity.38 ABCA1 proteins containing the sequence variants W590L, C1477F, D1706N, S1731C, or N1800H were all found to have significantly impaired cholesterol efflux, whereas the H551D and E1386Q variants had very minor, if any, effects on cholesterol transport (Figure 1A). Login to comment 50 ABCA1 p.His551Asp The H551D variant had close to normal efflux capacity but reduced cell surface presentation (Figure 1B), thereby affecting activity. Login to comment 70 ABCA1 p.Glu1386Gln ABCA1 p.His551Asp All mutants were found to have significantly impaired cholesterol efflux, with the exception of E1386Q and H551D. Login to comment 71 ABCA1 p.Ser1731Cys ABCA1 p.Ser1731Cys ABCA1 p.Glu1386Gln ABCA1 p.Glu1386Gln ABCA1 p.Gln2215* 0 2 4 6 8 10 m ock W T E1386Q C 1477F D 1706N S1731C N 1800H W 590L H 551D Q 2215X antibodybound (cpmx103 /mgcellprotein) 0 1 2 3 4 5 m ock W T E1386Q C 1477F D 1706N S1731C N 1800H W 590L H 551D Q 2215X apoA-Imediatedefflux(%)A B apoA-Imediatedefflux (%oftotalradioactivity) antibodybound (cpmx103/mgcellprotein) Figure 1. Login to comment 75 ABCA1 p.Glu1386Gln ABCA1 p.His551Asp ABCA1 p.His551Asp All mutants were found to have significantly impaired cholesterol efflux, with the exception of E1386Q and H551D. Login to comment 76 ABCA1 p.Gln2215* Q2215X is a truncation mutant and was used to demonstrate that the C terminus of ABCA1 is necessary for function, and therefore the 1851X mutant would also be nonfunctional. Login to comment 80 ABCA1 p.His551Asp The H551D mutant had significantly decreased cell surface presentation. Login to comment 83 ABCA1 p.Asn1800His ABCA1 p.Ser1731Cys ABCA1 p.Cys1477Phe ABCA1 p.Asp1706Asn ABCA1 p.His551Asp ABCA1 p.Trp590Leu of Subjects Functional Mutations (All Heterozygous) Percentage of Total Population ApoA-I 2 33X, èc;K182 2 ABCA1 7 H551D, W590L, C1477F, D1706N, S1731C, N1800H, 1851X 6 LCAT 4 W61X, G104S, N131D, S208T 3 PLTP 1 R459Q 1 Unknown 88 Total no. Login to comment 88 ABCA1 p.Asn1800His ABCA1 p.Ser1731Cys ABCA1 p.Cys1477Phe ABCA1 p.Asp1706Asn ABCA1 p.His551Asp ABCA1 p.Trp590Leu of Subjects Functional Mutations (All Heterozygous) Percentage of Total Population ApoA-I 2 33X, ⌬K182 2 ABCA1 7 H551D, W590L, C1477F, D1706N, S1731C, N1800H, 1851X 6 LCAT 4 W61X, G104S, N131D, S208T 3 PLTP 1 R459Q 1 Unknown 88 Total no. Login to comment 98 ABCA1 p.His551Asp As a positive control, we recruited first-degree relatives of a group B subject possessing a novel ABCA1 mutation, H551D. Login to comment 103 ABCA1 p.His551Asp As a positive control, we recruited first-degree relatives of a group B subject possessing a novel ABCA1 mutation, H551D. Login to comment 136 ABCA1 p.His551Asp Future studies will focus on the HDL 0.68 mM <5th% Efflux 0.31% HDL 1.25 mM 40th% Efflux 0.53% HDL 0.90 mM <5th% Efflux 0.28% HDL 0.85 mM <5th% Efflux 0.29% HDL 1.54 mM 70th% Efflux 0.49% HDL 0.60 mM <5th% Efflux 0.33% HDL 1.38 mM 50th% Efflux 0.56% HDL 0.90 mM 20th% Efflux 0.41% HDL 0.75 mM <5th% Efflux 0.21% HDL 0.91 mM 20th% Efflux 0.46% HDL 0.62 mM <5th% Efflux 0.35% HDL 1.40 mM 80th% Efflux 0.45% HDL 1.60 mM 90th% Efflux 0.58% HDL 0.72 mM <5th% Efflux 0.29% HDL 1.70 mM 75th% Efflux 0.49% HDL 0.60 mM <5th% Efflux 0.20% HDL 0.69 mM <5th% Efflux 0.38% HDL 0.78 mM <5th% Efflux 0.30% HDL 1.62 mM 75th% Efflux 0.55% Heritability of efflux defects Group B: H551D mut. Login to comment 140 ABCA1 p.His551Asp The proband and 2 children in the family depicted in the top left pedigree are carriers of a H551D mutation in ABCA1, demonstrating cosegregation of this mutation with a cholesterol efflux defect and low HDL. Login to comment 141 ABCA1 p.His551Asp Future studies will focus on the HDL 0.68 mM <5th% Efflux 0.31% HDL 1.25 mM 40th% Efflux 0.53% HDL 0.90 mM <5th% Efflux 0.28% HDL 0.85 mM <5th% Efflux 0.29% HDL 1.54 mM 70th% Efflux 0.49% HDL 0.60 mM <5th% Efflux 0.33% HDL 1.38 mM 50th% Efflux 0.56% HDL 0.90 mM 20th% Efflux 0.41% HDL 0.75 mM <5th% Efflux 0.21% HDL 0.91 mM 20th% Efflux 0.46% HDL 0.62 mM <5th% Efflux 0.35% HDL 1.40 mM 80th% Efflux 0.45% HDL 1.60 mM 90th% Efflux 0.58% HDL 0.72 mM <5th% Efflux 0.29% HDL 1.70 mM 75th% Efflux 0.49% HDL 0.60 mM <5th% Efflux 0.20% HDL 0.69 mM <5th% Efflux 0.38% HDL 0.78 mM <5th% Efflux 0.30% HDL 1.62 mM 75th% Efflux 0.55% Heritability of efflux defects Group B: H551D mut. Login to comment 145 ABCA1 p.His551Asp The proband and 2 children in the family depicted in the top left pedigree are carriers of a H551D mutation in ABCA1, demonstrating cosegregation of this mutation with a cholesterol efflux defect and low HDL. Login to comment