ABCMdb

ABCA1 p.Ser1506Leu

ClinVar:	c.4517C>T , p.Ser1506Leu D , Pathogenic
Predicted by SNAP2:	A: D (63%), C: D (66%), D: D (85%), E: D (75%), F: D (71%), G: D (71%), H: D (59%), I: D (75%), K: D (75%), L: D (75%), M: D (75%), N: D (71%), P: D (80%), Q: D (63%), R: D (75%), T: N (53%), V: D (71%), W: D (85%), Y: D (75%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: D, P: D, Q: D, R: D, T: D, V: D, W: D, Y: D,

[switch to compact view]
Comments [show]

None has been submitted yet.

Publications
[hide] Tangier disease caused by compound heterozygosity ... Atherosclerosis. 2010 Mar;209(1):163-6. Epub 2009 Aug 29. Cameron J, Ranheim T, Halvorsen B, Kulseth MA, Leren TP, Berge KE
Tangier disease caused by compound heterozygosity for ABCA1 mutations R282X and Y1532C.
Atherosclerosis. 2010 Mar;209(1):163-6. Epub 2009 Aug 29., [PMID:19765707]

Abstract [show]
BACKGROUND: Inherited low levels of high density lipoprotein (HDL) cholesterol may be due to mutations in the genes encoding the ATP-binding cassette transporter A1 (ABCA1), apolipoprotein (apo) A-I or lecithin:cholesterol acyltransferase (LCAT). METHODS: The ABCA1, apoA-I and LCAT genes of a 40-year-old male subject with serum HDL cholesterol of 0.06mmol/l were subjected to DNA sequencing. The proband's family was examined for co-segregation between mutations and levels of HDL cholesterol. Cholesterol efflux in fibroblasts from the proband and a normocholesterolemic subject was compared. The effects of an ABCA1 mutation on cholesterol efflux and membrane localization of ABCA1 were studied in transfected HEK293 and HeLa cells, respectively. RESULTS: The proband was a compound heterozygote for ABCA1 mutations R282X (c.844 C>T) and Y1532C (c.4595 A>G). Relatives who were heterozygous for one of these mutations, had about half-normal HDL cholesterol levels. Cholesterol efflux was reduced in fibroblasts from the proband, as was cholesterol efflux from HEK293 cells transfected with an human (h) ABCA1 expression plasmid harboring the Y1532C mutation. Confocal microscopy of HeLa cells transfected with the Y1532C-hABCA1 plasmid revealed that the Y1532C mutation inhibits ABCA1 from reaching the cellular membrane. CONCLUSION: Compound heterozygosity for the nonsense mutation R282X and the missense mutation Y1532C in the ABCA1 gene causes Tangier disease. R282X has a detrimental effect on the function of ABCA1 since a premature stop codon is introduced. Mutation Y1532C disrupts the normal function of ABCA1 as determined by in vitro analyses.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
121 Mutations C1477R and S1506L affecting residues in this loop, have been found to have no effect on the transport of ABCA1 [21], but the mutant proteins encoded by the two mutant alleles interacted much weaker with apoA-I than normal. Login to comment
123 On the other hand, significantly lower amounts of S1506L-ABCA1 were found at the cell surface. Login to comment
119 Mutations C1477R and S1506L affecting residues in this loop, have been found to have no effect on the transport of ABCA1 [21], but the mutant proteins encoded by the two mutant alleles interacted much weaker with apoA-I than normal. Login to comment

[hide] Severe HDL deficiency due to novel defects in the ... J Intern Med. 2009 Mar;265(3):359-72. Epub 2008 Oct 25. Pisciotta L, Bocchi L, Candini C, Sallo R, Zanotti I, Fasano T, Chakrapani A, Bates T, Bonardi R, Cantafora A, Ball S, Watts G, Bernini F, Calandra S, Bertolini S
Severe HDL deficiency due to novel defects in the ABCA1 transporter.
J Intern Med. 2009 Mar;265(3):359-72. Epub 2008 Oct 25., [PMID:19019193]

Abstract [show]
OBJECTIVES: The objective was the identification and functional characterization of mutations in the ABCA1 gene in four patients with severe HDL deficiency. SUBJECTS: Patients were referred to the clinic because of almost complete HDL deficiency. METHODS: The ABCA1 gene was sequenced directly. The analysis of the ABCA1 protein, ABCA1 mRNA and ABCA1-mediated cholesterol efflux was performed in cultured fibroblasts. Intracellular localization of ABCA1 mutants was investigated in transfected HEK293 cells. RESULTS: Two patients were homozygous for mutations in the coding region of the ABCA1 gene, resulting in an amino acid substitution (p.A1046D) and a truncated protein (p.I74YFsX76). The third patient was homozygous for a splice site mutation in intron 35 (c.4773 + 1g>a), resulting in an in-frame deletion of 25 amino acids (del p.D1567_K1591) in ABCA1. These patients had clinical manifestations of accumulation of cholesterol in the reticulo-endothelial system. The fourth patient, with preclinical atherosclerosis, was a compound heterozygote for two missense mutations (p.R587W/p.W1699C). ABCA1-mediated cholesterol efflux was abolished in fibroblasts from patients with p.A1046D and del p.D1567_K1591 mutants and in fibroblasts homozygous for p.R587W. A reduced ABCA1 protein content was observed in these cells, suggesting an increased intracellular degradation. The mutant p.W1699C was largely retained in the endoplasmic reticulum, when expressed in HEK293 cells. CONCLUSIONS: The homozygotes for mutations which abolish ABCA1 function showed overt signs of involvement of the reticulo-endothelial system. This was not the case in the compound heterozygote for missense mutations, suggesting that this patient retains some residual ABCA1 function that reduces cholesterol accumulation in the reticulo-endothelial system.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
197 Previous studies have shown that two missense ABCA1 mutants (p.C1477R and p.S1506L) located in the second extracellular loop, when expressed in transfected cells, exhibited a dramatic reduction in the interaction capacity with Apo A-I [27]. Login to comment

[hide] The role of different regions of ATP-binding casse... Biochemistry. 2007 Aug 21;46(33):9388-98. Epub 2007 Jul 26. Mukhamedova N, Fu Y, Bukrinsky M, Remaley AT, Sviridov D
The role of different regions of ATP-binding cassette transporter A1 in cholesterol efflux.
Biochemistry. 2007 Aug 21;46(33):9388-98. Epub 2007 Jul 26., [PMID:17655203]

Abstract [show]
ABCA1 is a key element of cholesterol efflux, but the mechanism of ABCA1-dependent cholesterol efflux is still unclear. Monoclonal antibodies against ABCA1 were used to map functional domains of ABCA1. Two antibodies were directed against a fragment of the first extracellular loop of ABCA1, and the third antibody was directed against a fragment of the fourth extracellular loop. One antibody against the first loop inhibited cholesterol efflux from human macrophages without inhibiting apolipoprotein A-I (apoA-I) binding and internalization. Another antibody against the first loop inhibited apoA-I binding and internalization without inhibiting cholesterol efflux. The antibody against the fourth loop inhibited apoA-I binding to ABCA1 but enhanced cholesterol efflux from macrophages and reduced intracellular cholesterol content. This antibody also increased cholesterol efflux from HeLa cells transfected with ABCA1 but not from cells with DeltaPEST-ABCA1. The mechanism of the stimulating effect of this antibody on cholesterol efflux was found to be stabilization of ABCA1 leading to the increase in abundance of cell surface ABCA1. We conclude that a site on the first extracellular loop is required for cholesterol efflux, whereas a site on the fourth extracellular loop may be responsible for ABCA1 stability.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
269 Natural mutations found in the Tangier pedigree, R587W, W590S, Q597R, and S1506L, as well as generated mutant C1477R strongly inhibited cholesterol and phospholipid efflux (28, 35, 36) and, with the exception of W590S, also apoA-I binding (36). Login to comment

[hide] Specific mutations in ABCA1 have discrete effects ... Circ Res. 2006 Aug 18;99(4):389-97. Epub 2006 Jul 27. Singaraja RR, Visscher H, James ER, Chroni A, Coutinho JM, Brunham LR, Kang MH, Zannis VI, Chimini G, Hayden MR
Specific mutations in ABCA1 have discrete effects on ABCA1 function and lipid phenotypes both in vivo and in vitro.
Circ Res. 2006 Aug 18;99(4):389-97. Epub 2006 Jul 27., [PMID:16873719]

Abstract [show]
Mutations in ATP-binding cassette transporter A1 (ABCA1) cause Tangier disease and familial hypoalphalipoproteinemia, resulting in low to absent plasma high-density lipoprotein cholesterol levels. However, wide variations in clinical lipid phenotypes are observed in patients with mutations in ABCA1. We hypothesized that the various lipid phenotypes would be the direct result of discrete and differing effects of the mutations on ABCA1 function. To determine whether there is a correlation between the mutations and the resulting phenotypes, we generated in vitro 15 missense mutations that have been described in patients with Tangier disease and familial hypoalphalipoproteinemia. Using localization of ABCA1, its ability to induce cell surface binding of apolipoprotein A-I, and its ability to elicit efflux of cholesterol and phospholipids to apolipoprotein A-I we determined that the phenotypes of patients correlate with the severity and nature of defects in ABCA1 function.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
50 Two mutants, A1046D and S1506L, showed an intermediate phenotype where plasma membrane localization was reduced (Figure 2A). Login to comment
56 S1506L, which appeared to have partial plasma membrane localization, showed a digestion pattern essentially similar to wild-type ABCA1, supporting the notion that a portion of S1506L is localized at the plasma membrane. Login to comment
58 R587W, Q597R, ⌬L693, S1506L, and R2081W showed significantly reduced cell surface ABCA1 expression, confirming our previous localization data. Login to comment
71 The A1046D and S1506L mutants displayed a partial ability to induce cell surface ApoA-I binding (56.3Ϯ16.4%, nϭ3, Pϭ0.02 and 61.0Ϯ12.7%, nϭ3, Pϭ0.004, respectively; Figure 3A), suggesting that in these mutants, some of the protein is localized at the plasma membrane. Login to comment
79 A1046D and S1506L showed reduced localization at the plasma membrane, and C1477R, D1289L, and P2150L showed localization at the plasma membrane and intracellularly. Login to comment
82 C1477R, S1506L, and R2081W show both EndoH sensitive and resistant bands indicating localization at both the ER and the plasma membrane. Login to comment
152 Both A1046D and S1506L were partially localized at the plasma membrane and showed significantly reduced ApoA-I binding. Login to comment
153 The data for S1506L agree with previous data.25 The S1506L mutation also occurs in the second large extracellular portion of ABCA1 and may potentially destroy a domain of interaction for the extracellular loops necessary for ApoA-I binding. Login to comment

[hide] Role of apoA-I, ABCA1, LCAT, and SR-BI in the biog... J Mol Med (Berl). 2006 Apr;84(4):276-94. Epub 2006 Feb 25. Zannis VI, Chroni A, Krieger M
Role of apoA-I, ABCA1, LCAT, and SR-BI in the biogenesis of HDL.
J Mol Med (Berl). 2006 Apr;84(4):276-94. Epub 2006 Feb 25., [PMID:16501936]

Abstract [show]
The concentration, composition, shape, and size of plasma high-density lipoprotein (HDL) are determined by numerous proteins that influence its biogenesis, remodeling, and catabolism. The discoveries of the HDL receptor (scavenger receptor class B type I, SR-BI) and the ABCA1 (ATP-binding cassette transporter A1) lipid transporter provided two missing links that were necessary to understand the biogenesis and some of the functions of HDL. Existing data indicate that functional interactions between apoA-I and ABCA1 are necessary for the initial lipidation of apoA-I. Through a series of intermediate steps, lipidated apoA-I proceeds to form discoidal HDL particles that can be converted to spherical particles by the action of lecithin:cholesterol acyltransferase (LCAT). Discoidal and spherical HDL can interact functionally with SR-BI and these interactions lead to selective lipid uptake and net efflux of cholesterol and thus remodel HDL. Defective apoA-I/ABCA1 interactions prevent lipidation of apoA-I that is necessary for the formation of HDL particles. In the same way, specific mutations in apoA-I or LCAT prevent the conversion of discoidal to spherical HDL particles. The interactions of lipid-bound apoA-I with SR-BI are affected in vitro by specific mutations in apoA-I or SR-BI. Furthermore, deficiency of SR-BI affects the lipid and apolipoprotein composition of HDL and is associated with increased susceptibility to atherosclerosis. Here we review the current status of the pathway of HDL biogenesis and mutations in apoA-I, ABCA1, and SR-BI that disrupt different steps of the pathway and may lead to dyslipidemia and atherosclerosis in mouse models. The phenotypes generated in experimental mouse models for apoA-I, ABCA1, LCAT, SR-BI, and other proteins of the HDL pathway may facilitate early diagnosis of similar phenotypes in the human population and provide guidance for proper treatment.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
147 In vitro analysis of the effects on apoA-I/ABCA1 interactions (cross-linking assay) by mutations in ABCA1 that are found in Tangier disease patients and diminish lipid efflux [71] showed that cross-linking was dramatically reduced to 5-10% of the WT control for three mutants (Gln597Arg, Cys1477Arg, and Ser1506Leu), reduced by 50% for the Arg587Trp mutant, and was remarkably increased to 125% of control for the Trp590Ser mutant [71]. Login to comment

[hide] Accurate prediction of the functional significance... PLoS Genet. 2005 Dec;1(6):e83. Epub 2005 Dec 30. Brunham LR, Singaraja RR, Pape TD, Kejariwal A, Thomas PD, Hayden MR
Accurate prediction of the functional significance of single nucleotide polymorphisms and mutations in the ABCA1 gene.
PLoS Genet. 2005 Dec;1(6):e83. Epub 2005 Dec 30., [PMID:16429166]

Abstract [show]
The human genome contains an estimated 100,000 to 300,000 DNA variants that alter an amino acid in an encoded protein. However, our ability to predict which of these variants are functionally significant is limited. We used a bioinformatics approach to define the functional significance of genetic variation in the ABCA1 gene, a cholesterol transporter crucial for the metabolism of high density lipoprotein cholesterol. To predict the functional consequence of each coding single nucleotide polymorphism and mutation in this gene, we calculated a substitution position-specific evolutionary conservation score for each variant, which considers site-specific variation among evolutionarily related proteins. To test the bioinformatics predictions experimentally, we evaluated the biochemical consequence of these sequence variants by examining the ability of cell lines stably transfected with the ABCA1 alleles to elicit cholesterol efflux. Our bioinformatics approach correctly predicted the functional impact of greater than 94% of the naturally occurring variants we assessed. The bioinformatics predictions were significantly correlated with the degree of functional impairment of ABCA1 mutations (r2 = 0.62, p = 0.0008). These results have allowed us to define the impact of genetic variation on ABCA1 function and to suggest that the in silico evolutionary approach we used may be a useful tool in general for predicting the effects of DNA variation on gene function. In addition, our data suggest that considering patterns of positive selection, along with patterns of negative selection such as evolutionary conservation, may improve our ability to predict the functional effects of amino acid variation.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
48 This SNP has been reported to be associated with decreased HDL cholesterol and increased severity of atherosclerosis in Table 1. subPSEC Scores and Probability of Functional Impairment (Pdeleterious) for ABCA1 Mutations and SNPs Mutations SNPs Variant SubPSEC Pdeleterious Variant subPSEC Pdeleterious P85L À4.62 0.83 R219K À0.57 0.08 H160F À2.79 0.45 V399A À2.26 0.32 R230C À4.27 0.78 V771M À2.86 0.46 A255T À1.81 0.23 T774P À1.99 0.27 E284K À2.34 0.34 K776N À3.53 0.63 Y482C À4.21 0.77 V825I À1.06 0.13 R587W À6.04 0.95 I883M À1.38 0.17 W590S À5.19 0.9 E1172D À1.96 0.26 W590L À4.48 0.82 R1587K À0.58 0.08 Q597R À7.15 0.98 S1731C À4.21 0.77 T929I À4.29 0.78 N935H À8.54 1 N935S À7.53 0.99 A937V À6.6 0.97 A1046D À7.52 0.99 M1091T À3.56 0.64 D1099Y À6.09 0.96 D1289N À2.48 0.37 L1379F À3.81 0.69 C1477R À5.44 0.92 S1506L À5.17 0.9 N1611D À5.69 0.94 R1680W À6.02 0.95 V1704D À3.21 0.55 N1800H À4.23 0.77 R1901S À5.06 0.89 F2009S À2.73 0.43 R2081W À8.08 0.99 P2150L À2.88 0.47 Q2196H À2.74 0.43 DOI: 10.1371/journal.pgen.0010083.t001 PLoS Genetics | www.plosgenetics.org December 2005 | Volume 1 | Issue 6 | e83 0740 Accurate Prediction of ABCA1 Variants Synopsis A major goal of human genetics research is to understand how genetic variation leads to differences in the function of genes. Login to comment
75 Cholesterol Efflux Values for 293 Cells Transfected with ABCA1 Variants and subPSEC and PolyPhen Predictions of the Functional Impact of these Variants Variant Variant Type subPSEC Cholesterol Efflux PolyPhen R2081W Mutation À8.08 21.1 6 21%* Probably damaging N935S Mutation À7.53 29.3 6 13%* Benign A1046D Mutation À7.52 16.8 6 7%* Possibly damaging Q597R Mutation À7.15 17.7 6 14%* Probably damaging R587W Mutation À6.04 31.7 6 33%* Probably damaging C1477R Mutation À5.44 20.5 6 10%* Probably damaging W590S Mutation À5.19 47.1 6 13%* Probably damaging S1506L Mutation À5.17 17.8 6 15%* Probably damaging T929I Mutation À4.29 69.9 6 11%* Possibly damaging N1800H Mutation À4.23 31.3 6 16%* Possibly damaging S1731C SNP À4.21 12.3 6 10%* Possibly damaging M1091T Mutation À3.56 6.9 6 20%* Probably damaging P2150L Mutation À2.88 88.4 6 21% Probably damaging V771M SNP À2.86 145.4 6 33% Benign D1289N Mutation À2.48 137.7 6 86% Benign I883M SNP À1.38 69.1 6 16%* Benign R219K SNP À0.57 103.7 6 21.05 Benign Wild-type - 0.0 100% - *p , 0.01 compared to wild-type ABCA1. Login to comment

[hide] Two novel missense mutations in ABCA1 result in al... Biochim Biophys Acta. 2004 May 24;1689(1):47-57. Albrecht C, Baynes K, Sardini A, Schepelmann S, Eden ER, Davies SW, Higgins CF, Feher MD, Owen JS, Soutar AK
Two novel missense mutations in ABCA1 result in altered trafficking and cause severe autosomal recessive HDL deficiency.
Biochim Biophys Acta. 2004 May 24;1689(1):47-57., [PMID:15158913]

Abstract [show]
Extremely low concentrations of high density lipoprotein (HDL)-cholesterol and apolipoprotein (apo) AI are features of Tangier disease caused by autosomal recessive mutations in ATP-binding cassette transporter A1 (ABCA1). Less deleterious, but dominantly inherited mutations cause HDL deficiency. We investigated causes of severe HDL deficiency in a 42-year-old female with progressive coronary disease. ApoAI-mediated efflux of cholesterol from the proband's fibroblasts was less than 10% of normal and nucleotide sequencing revealed inheritance of two novel mutations in ABCAI, V1704D and L1379F. ABCA1 mRNA was approximately 3-fold higher in the proband's cells than in control cells; preincubation with cholesterol increased it 5-fold in control and 8-fold in the proband's cells, but similar amounts of ABCA1 protein were present in control and mutant cells. When transiently transfected into HEK293 cells, confocal microscopy revealed that both mutant proteins were retained in the endoplasmic reticulum, while wild-type ABCA1 was located at the plasma membrane. Severe HDL deficiency in the proband was caused by two novel autosomal recessive mutations in ABCA1, one (V1704D) predicted to lie in a transmembrane segment and the other (L1379F) in a large extracellular loop. Both mutations prevent normal trafficking of ABCA1, thereby explaining their inability to mediate apoA1-dependent lipid efflux.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
215 Two of these, C1477R and S1506L, do not appear to disrupt transport of the protein to the cell surface, as judged by the accessibility of the protein in non-permeabilised cells, but the mutant proteins are unable to mediate cholesterol efflux [38]. Login to comment
214 Two of these, C1477R and S1506L, do not appear to disrupt transport of the protein to the cell surface, as judged by the accessibility of the protein in non-permeabilised cells, but the mutant proteins are unable to mediate cholesterol efflux [38]. Login to comment

[hide] Efflux and atherosclerosis: the clinical and bioch... Arterioscler Thromb Vasc Biol. 2003 Aug 1;23(8):1322-32. Epub 2003 May 22. Singaraja RR, Brunham LR, Visscher H, Kastelein JJ, Hayden MR
Efflux and atherosclerosis: the clinical and biochemical impact of variations in the ABCA1 gene.
Arterioscler Thromb Vasc Biol. 2003 Aug 1;23(8):1322-32. Epub 2003 May 22., [PMID:12763760]

Abstract [show]
Approximately 50 mutations and many single nucleotide polymorphisms have been described in the ABCA1 gene, with mutations leading to Tangier disease and familial hypoalphalipoproteinemia. Homozygotes and heterozygotes for mutations in ABCA1 display a wide range of phenotypes. Identification of ABCA1 as the molecular defect in these diseases has allowed for ascertainment based on genetic status and determination of genotype-phenotype correlations and has permitted us to identify mutations conferring a range of severity of cellular, biochemical, and clinical phenotypes. In this study we review how genetic variation at the ABCA1 locus affects its role in the maintenance of lipid homeostasis and the natural progression of atherosclerosis.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
80 However, failure of binding may also occur because of disruption of residues crucial for this function. Indeed, the variants C1477R and S1506L, which are both localized in the second large extracellular loop, are normally translocated to the plasma membrane but show no ApoA-I binding, indicating that specific amino acids in the large extracellular loops are Figure 4. Login to comment
83 TABLE 2. Conservation of Amino Acid Residues Mutated in Humans Mutation H. sapiens M. musculus G. gallus D. melanogaster C. elegans P85L P P P ⅐ ⅐ ⅐ P R230C R R R P G A255T A A S ⅐ ⅐ ⅐ ⅐ ⅐ ⅐ R587W R R R ⅐ ⅐ ⅐ ⅐ ⅐ ⅐ W590S W W W R Q Q597R Q Q Q Q Q ⌬L693 L L L L L T929I T T T T T N935S/H N N N N N A937V A A A A A A1046D A A A A A M1091T M M M M M D1099Y D D D D D D1289L/N D D D D D C1477R C C C ⅐ ⅐ ⅐ ⅐ ⅐ ⅐ S1506L S S S ⅐ ⅐ ⅐ ⅐ ⅐ ⅐ N1611D N N N N S R1680W R R R R R N1800H N N N A W F2009S F F F I M R2081W R R R R R P2150L P P P R N ⌬E1893 E E E D S ⌬D1894 D D D D D Twenty-three of 24 (95.83%) amino acids affected by mutations are conserved with G. gallus, reflecting the functional importance of these residues. Login to comment
72 However, failure of binding may also occur because of disruption of residues crucial for this function. Indeed, the variants C1477R and S1506L, which are both localized in the second large extracellular loop, are normally translocated to the plasma membrane but show no ApoA-I binding, indicating that specific amino acids in the large extracellular loops are Figure 4. Login to comment
75 TABLE 2. Conservation of Amino Acid Residues Mutated in Humans Mutation H. sapiens M. musculus G. gallus D. melanogaster C. elegans P85L P P P ዼ ዼ ዼ P R230C R R R P G A255T A A S ዼ ዼ ዼ ዼ ዼ ዼ R587W R R R ዼ ዼ ዼ ዼ ዼ ዼ W590S W W W R Q Q597R Q Q Q Q Q èc;L693 L L L L L T929I T T T T T N935S/H N N N N N A937V A A A A A A1046D A A A A A M1091T M M M M M D1099Y D D D D D D1289L/N D D D D D C1477R C C C ዼ ዼ ዼ ዼ ዼ ዼ S1506L S S S ዼ ዼ ዼ ዼ ዼ ዼ N1611D N N N N S R1680W R R R R R N1800H N N N A W F2009S F F F I M R2081W R R R R R P2150L P P P R N èc;E1893 E E E D S èc;D1894 D D D D D Twenty-three of 24 (95.83%) amino acids affected by mutations are conserved with G. gallus, reflecting the functional importance of these residues. Login to comment

[hide] Genetics of HDL regulation in humans. Curr Opin Lipidol. 2003 Jun;14(3):273-9. Miller M, Rhyne J, Hamlette S, Birnbaum J, Rodriguez A
Genetics of HDL regulation in humans.
Curr Opin Lipidol. 2003 Jun;14(3):273-9., [PMID:12840658]

Abstract [show]
PURPOSE OF REVIEW: To review gene regulation of HDL-cholesterol and discuss molecular abnormalities in HDL candidate genes that may lead to human pathologic states. RECENT FINDINGS: The inverse association between HDL-cholesterol and vascular disease, especially coronary heart disease, has long been recognized, but understanding gene regulation of HDL in humans gained considerable momentum following the identification of ABCA1 as playing a pivotal role in reverse cholesterol transport. Recent data suggest that potentially important targets for upregulating HDL in humans include upregulators of ABCA1 and APOA1 (e.g. peroxisome proliferator activated receptor and liver X receptor agonists) and downregulators of CETP (e.g. JTT-705). A host of other nuclear receptors under investigation in animal models may advance to human testing in the near future. SUMMARY: Disorders affecting HDL metabolism are complex because monogenic disorders causing low HDL do not necessarily correlate with premature vascular disease. To date, pathologic phenotypes have only been deduced among several HDL candidate genes. Understanding the genetic underpinnings associated with variant HDL and reverse cholesterol transport provides an exceptional opportunity to identify novel agents that may optimize this process and reduce vascular event rates beyond currently available LDL lowering therapies.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
66 TD 1591 T/C 11 V399A extracellular [68] TD 1979 (110bpAlu Ins) 12 truncated truncation [60] TD/FHA 2154 C/T 14 R587W extracellular [67,69] TD 2164 G/C 14 W590S extracellular [61] TD 2185 A/G 14 Q597R extracellular [59,67] TD 2219 G/del 14 truncated, 635X truncated [60,61] FHA 2472-2474 3bp del 15 Del L693 TM domain #3 [59] phosphorylation 2706 G/A 16 V771M extracellular [68] 2715 A/C 16 T774P extracellular [68] 2723 G/C 16 K776N extracellular [68] 2868 G/A 17 V825I TM domain #6 [67,68] TD/FHA 3044 A/G 18 I883M cytoplasmic [68] phosphorylat site FHA 3120 C/T 19 R909X truncation [63,71] TD 3181 C/T 19 T929I cytoplasmic [62] TD 3199 A/G 19 N935S Walker A [61] TD 3205 C/T 19 A937V Walker A [61] TD 3532 C/A 22 A1046D cytoplasmic, Walker A/B [70] FHA 3667 T/C 23 M1091T cytoplasmic [63] 3690 G/T 23 D1099Y cytoplasmic [9] TD 3738 2bp del 23 1145X truncation [66] FHA 3911 G/C 24 E1172D linker/cytoplasmic [68] FHA 4242 4bp del 27 1297X truncated [64] TD 4260 G/A 27 D1289N linker cytoplasm [64,65] TD 4824 T/C 31 C1477R extracellular [59] TD 4912 C/T 32 S1506L extracellular loop #2 [71] TD 5025 ins A 34 A1544S?1552X truncation [70] 5059 T/C 34 I1555T extracellular loop #2 [67] 5155 G/A 35 R1587K extracellular loop #2 [68] FHA 5226 A/G 36 N1611D extracellular loop #2 [75..] 5338 T/C 36 L1648P extracellular loop #2 [67] TD 5443 C/T 37 R1680W cytoplasmic [74.] Login to comment

[hide] Naturally occurring mutations in the largest extra... J Biol Chem. 2002 Sep 6;277(36):33178-87. Epub 2002 Jun 25. Fitzgerald ML, Morris AL, Rhee JS, Andersson LP, Mendez AJ, Freeman MW
Naturally occurring mutations in the largest extracellular loops of ABCA1 can disrupt its direct interaction with apolipoprotein A-I.
J Biol Chem. 2002 Sep 6;277(36):33178-87. Epub 2002 Jun 25., [PMID:12084722]

Abstract [show]
The ABCA1 transporter contains two large domains into which many of the genetic mutations in individuals with Tangier disease fall. To investigate the structural requirements for the cellular cholesterol efflux mediated by ABCA1, we have determined the topology of these two domains and generated transporters harboring five naturally occurring missense mutations in them. These mutants, unlike wild type ABCA1, produced little or no apoA-I-stimulated cholesterol efflux when transfected into 293 cells, establishing their causality in Tangier disease. Because all five mutant proteins were well expressed and detectable on the plasma membrane, their interaction with the ABCA1 ligand, apolipoprotein (apo) A-I, was measured using bifunctional cross-linking agents. Four of five mutants had a marked decline in cross-linking to apoA-I, whereas one (W590S) retained full cross-linking activity. Cross-linking of apoA-I was temperature-dependent, rapid in onset, and detectable with both lipid- and water-soluble cross-linking agents. These results suggest that apoA-I-stimulated cholesterol efflux cannot occur without a direct interaction between the apoprotein and critical residues in two extracellular loops of ABCA1. The behavior of the W590S mutant indicates that although binding of apoA-I by ABCA1 may be necessary, it is not sufficient for stimulation of cholesterol efflux.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
39 DNA Constructs-Five missense mutants of ABCA1 (R587W, W590S, Q597R, C1477R, and S1506L) were generated using overlap polymerase chain reaction methods, as described previously (17). Login to comment
70 Missense Mutations in Two Putative Extracellular Loops of ABCA1 Ablate Efflux Activity-Five missense mutations (R587W, W590S, Q597R, C1477R, and S1506L) were introduced into a wild type ABCA1 cDNA using PCR mutagenesis techniques. Login to comment
72 The other two mutations (C1477R and S1506L) fall within the central loop of the protein. Login to comment
116 The cells were transfected with either empty vector (mock), wild type ABCA1 (WT), or ABCA1 constructs carrying the indicated point mutations (R587W, W590S, Q597R, C1477R, and S1506L). Login to comment
119 Absolute apoA-I and medium efflux values, respectively, are as follows: mock, 1.59 Ϯ 0.04% versus 1.21 Ϯ 0.39%; WT, 3.92 Ϯ 0.13% versus 1.9 Ϯ 0.08%; R587W, 1.78 Ϯ 0.11% versus 1.61 Ϯ 0.24%; W590S, 1.92 Ϯ 0.24% versus 1.63 Ϯ 0.08%; Q597R, 1.5 Ϯ 0.14% versus 1.49 Ϯ 0.03%; C1477R, 1.67 Ϯ 0.18% versus 1.52 Ϯ 0.15%; and S1506L, 1.66 Ϯ 0.28% versus 1.6 Ϯ 0.13%. Login to comment
198 Three of the mutants (Q597R, C1477R, and S1506L) had dramatic reductions in their cross-linking efficiency to apoA-I, relative to the wild type transporter (90% or greater reduction). Login to comment
202 DISCUSSION In this study, we have established that several naturally occurring missense mutations in ABCA1 (R587W, W590S, Q597R, C1477R, and S1506L) located in the two largest loop domains of the protein (comprising amino acids ϳ44-640 and ϳ1371-1649, respectively) are, in fact, loss-of-function mutations. Login to comment
212 Although three of the mutations (Q597R, C1477R, and S1506L) showed no appreciable cross-linking to apoA-I, the R587W mutant had an intermediate activity, and the W590S mutant retained full, if not enhanced, cross-linking to the apoprotein. Login to comment
37 DNA Constructs-Five missense mutants of ABCA1 (R587W, W590S, Q597R, C1477R, and S1506L) were generated using overlap polymerase chain reaction methods, as described previously (17). Login to comment
67 Missense Mutations in Two Putative Extracellular Loops of ABCA1 Ablate Efflux Activity-Five missense mutations (R587W, W590S, Q597R, C1477R, and S1506L) were introduced into a wild type ABCA1 cDNA using PCR mutagenesis techniques. Login to comment
69 The other two mutations (C1477R and S1506L) fall within the central loop of the protein. Login to comment
112 The cells were transfected with either empty vector (mock), wild type ABCA1 (WT), or ABCA1 constructs carrying the indicated point mutations (R587W, W590S, Q597R, C1477R, and S1506L). Login to comment
115 Absolute apoA-I and medium efflux values, respectively, are as follows: mock, 1.59 afe; 0.04% versus 1.21 afe; 0.39%; WT, 3.92 afe; 0.13% versus 1.9 afe; 0.08%; R587W, 1.78 afe; 0.11% versus 1.61 afe; 0.24%; W590S, 1.92 afe; 0.24% versus 1.63 afe; 0.08%; Q597R, 1.5 afe; 0.14% versus 1.49 afe; 0.03%; C1477R, 1.67 afe; 0.18% versus 1.52 afe; 0.15%; and S1506L, 1.66 afe; 0.28% versus 1.6 afe; 0.13%. Login to comment
190 Three of the mutants (Q597R, C1477R, and S1506L) had dramatic reductions in their cross-linking efficiency to apoA-I, relative to the wild type transporter (90% or greater reduction). Login to comment
194 DISCUSSION In this study, we have established that several naturally occurring missense mutations in ABCA1 (R587W, W590S, Q597R, C1477R, and S1506L) located in the two largest loop domains of the protein (comprising amino acids b03;44-640 and b03;1371-1649, respectively) are, in fact, loss-of-function mutations. Login to comment
204 Although three of the mutations (Q597R, C1477R, and S1506L) showed no appreciable cross-linking to apoA-I, the R587W mutant had an intermediate activity, and the W590S mutant retained full, if not enhanced, cross-linking to the apoprotein. Login to comment

[hide] ABCA1 mediates unfolding of apolipoprotein AI N te... Arterioscler Thromb Vasc Biol. 2013 Jun;33(6):1197-205. doi: 10.1161/ATVBAHA.112.301195. Epub 2013 Apr 4. Wang S, Gulshan K, Brubaker G, Hazen SL, Smith JD
ABCA1 mediates unfolding of apolipoprotein AI N terminus on the cell surface before lipidation and release of nascent high-density lipoprotein.
Arterioscler Thromb Vasc Biol. 2013 Jun;33(6):1197-205. doi: 10.1161/ATVBAHA.112.301195. Epub 2013 Apr 4., [PMID:23559627]

Abstract [show]
OBJECTIVE: To gain insight into the mechanism by which ABCA1 generates nascent high-density lipoprotein. APPROACH AND RESULTS: HEK293 cells were stably transfected with ABCA1 vectors, encoding wild type, and the W590S and C1477R Tangier disease mutation isoforms, along with the K939M ATP-binding domain mutant. Apolipoprotein AI (ApoAI) binding, plasma membrane remodeling, cholesterol efflux, apoAI cell surface unfolding, and apoAI cell surface lipidation were determined, the latter 2 measured using novel fluorescent apoAI indicators. The W590S isoform had decreased plasma membrane remodeling and lipid efflux activities, and the C1477R isoform had decreased apoAI binding, and lipid efflux activities, whereas the K939M isoform did not bind apoAI, remodel the membrane, or efflux cholesterol. However, all ABCA1 isoforms led to apoAI unfolding at the cell surface, which was higher for the isoforms that increased apoAI binding. ApoAI lipidation was not detected on ABCA1-expressing cells, only in the conditioned medium, consistent with rapid release of nascent high-density lipoprotein from ABCA1-expressing cells. CONCLUSIONS: We identified a third activity of ABCA1, the ability to unfold the N terminus of apoAI on the cell surface. Our results support a model in which unfolded apoAI on the cell surface is an intermediate in its lipidation and that, once apoAI is lipidated, it forms an unstable structure that is rapidly released from the cells to generate high-density lipoprotein.

Comments [show]

None has been submitted yet.

Sentences [show]
No. Sentence Comment
114 Fitzgerald et al17 examined 5 Tangier disease mutations that mapped to the 2 large extracellular domains, and reported that only the W590S mutation in the first extracellular domain was still competent to mediate apoAI cross-linking, whereas other mutations in the first (R587W and Q597R) and second (C1477R and S1506L) extracellular domains could not mediate apoAI cross-linking. Login to comment