ABCMdb

PMID: 16103129

Wiszniewski W, Zaremba CM, Yatsenko AN, Jamrich M, Wensel TG, Lewis RA, Lupski JR
ABCA4 mutations causing mislocalization are found frequently in patients with severe retinal dystrophies.
Hum Mol Genet. 2005 Oct 1;14(19):2769-78. Epub 2005 Aug 15., [PubMed]

Sentences

No. Mutations Sentence Comment

2 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Arg602Trp ABCA4 p.Arg408* We analyzed a cohort of 29 arRP families for the mutations in ABCA4 with a commercial microarray, ABCR-400 in addition to direct sequencing and segregation analysis, and identified both mutant alleles in two families (7%): compound heterozygosity for missense (R602W) and nonsense (R408X) alleles and homozygosity for a complex [L541P; A1038V] allele. Login to comment 26 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp Functional studies of missense alleles [L541P; A1038V], R602W and C1490Y in transgenic frogs demonstrate that they do not translocate to rod OSs (ROSs). Login to comment 33 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro The sequence analysis of ABCA4 in patients AR197-05 and AR197-06 revealed homozygosity for the complex ABCA4 allele [L541P; A1038V]. Login to comment 36 ABCA4 p.Arg602Trp ABCA4 p.Arg408* Sequence analysis of patient AR689-03 revealed compound heterozygosity for the missense ABCA4 alteration R602W and a nonsense allele, R408X. Login to comment 39 ABCA4 p.Gly1961Glu ABCA4 p.Val2050Leu arRP patients from five families (AR168, AR192, AR194, AR554 and AR591) were heterozygous for various missense ABCA4 mutations that by conceptual translation would lead to either an amino acid change (G1961E, V2050L and D2177 N) or splicing alteration (36IVSþ1G . Login to comment 44 ABCA4 p.Gly1961Glu ABCA4 p.Asp2177Asn ABCA4 p.Asp2177Asn ABCA4 p.Asp2177Asn ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Arg602Trp ABCA4 p.Val2050Leu ABCA4 p.Arg408* A WT 168-05 24 20/25 OD; 20/30 OS;VF , 308 OU RP N/A N/A 168-06 26 N/A RP N/A N/A AR192 192-03 9 20/20 OD; 20/25 OS;VF , 58 OU RP D2177N WT 192-04 19 20/30 OD; 20/40 OS;VF , 58 OU RP WT WT 192-05 19 20/30 OD; 20/40 OS;VF , 58 OU RP WT WT AR194 194-03 30 N/A RP D2177N WT 194-05 Childhood 20/25 OD; 20/40 OS RP N/A N/A 194-06 5 N/A RP D2177N WT 194-07 4 or 5 20/80 OU RP N/A N/A AR197 197-05 7 CF 3 feet OD; CF 2 feet OS RP [L541P; A1038V] [L541P; A1038V] 197-06 9 CF 5 feet OD; HM OS RP [L541P; A1038V] [L541P; A1038V] AR554 554-03 2 10/12 20/60 OU RP V2050L WT 554-04 1 9/12 N/A RP N/A N/A AR591 591-03 20 20/25 OU RP N/A N/A 591-04 8 20/20 OD; 20/25 OS;VF , 108 OU RP G1961E WT AR689 689-03 7 N/A RP R408X R602W 689-08 7 N/A RP N/A N/A OD, right eye; OS, left eye; OU, both eyes; VF, visual field; RP, retinitis pigementosa, WT, wild type; N/A, not available; CF, counting fingers; HM, hand motions. Login to comment 80 ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp (C-L) Microphotographs of 2-week-old X. laevis tadpoles expressing R602W (C and D), [L541P; A1038V] (E and F), L541P (G and H), A1038V (I and J) and C1490Y (K and L). Login to comment 81 ABCA4 p.Ala1038Val Rod photoreceptors expressing each of the mutant proteins, except A1038V, demonstrated localization of the transgenic protein to the rod inner segment and cell body. Login to comment 82 ABCA4 p.Leu541Pro Misfolded proteins are homogenously distributed in the inner segments and cell bodies, although the presence of fine aggregates was noted for L541P. Login to comment 83 ABCA4 p.Ala1038Val Mutation A1038V does not influence the localization of ABCA4 and the mutant protein was found in the ROS. Login to comment 88 ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp RP-associated mutants are misfolded and retained in the rod IS To investigate effects of the presumably severe arRP-associated R602W missense allele on ABCA4 localization, transgenic tadpoles were generated with the R602W construct. Login to comment 89 ABCA4 p.Arg602Trp IF analysis of the retina demonstrated the retention of transgenic R602W in the IS (Fig. 2C and D). Login to comment 92 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Arg602Trp Functional studies of the arRP-associated complex allele [L541P; A1038V] also showed abnormal localization to rod IS although the IF studies revealed a different staining pattern than R602W, because the mutant protein forms fine aggregates in the IS (Fig. 2E and F). Login to comment 93 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Arg602Trp The aggregate formation suggests a mechanism distinct from that observed for R602W may be responsible for the retention of [L541P; A1038V] in the IS. Login to comment 94 ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro To determine which mutation prevents translocation of [L541P; A1038V] to ROS, we examined functionally the L541P and A1038V mutants independently. Login to comment 95 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro We observed retention of L541P in the IS (Fig. 2G and H) and correct localization of A1038V to ROS (Fig. 2I and J). Login to comment 96 ABCA4 p.Leu541Pro These results suggest that L541P is a disease-causing mutation that affects ABCA4 processing. Login to comment 97 ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr Mutation C1490Y causes retention of ABCA4 to rod IS The ABCA4 C1490Y allele has been found in patients presenting with both STGD and CRD. Login to comment 99 ABCA4 p.Cys1490Tyr Therefore, we sought to explore the effect of C1490Y mutation on ABCA4 processing. Login to comment 100 ABCA4 p.Cys1490Tyr We found that C1490Y causes retention of the mutated protein in the IS (Fig. 2K and L). Login to comment 101 ABCA4 p.Arg602Trp Similar to the staining pattern found in R602W, the IS compartment was stained homogenously suggesting impaired folding. Login to comment 104 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp We employed this assay to examine the effects of [L541P; A1038V], R602W and C1490Y mutations on in vitro ATP hydrolysis. Login to comment 107 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro The rate of ATP hydrolysis of the complex allele [L541P; A1038V] was decreased to 68.1% of wild-type ABCA4 (Fig. 3). Login to comment 108 ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp In addition, we observed a marked decrease in ATP hydrolytic activity compared with wild-type in both R602W (21.6%) and C1490Y (21.4%) alleles. Login to comment 112 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro Decreased ATPase activity does not likely contribute to the overall pathogenicity of [L541P; A1038V] because localization to the ROS is the primary event that determines placement of the protein in its natural environment and is presumably required for it to perform its physiological function. Login to comment 113 ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp Mutations: R602W, [L541P; A1038V] and C1490Y are frequently detected in patients with retinal diseases Mislocalization mutations R602W, [L541P; A1038V] and C1490Y have been reported as disease-associated mutations in patients with RP, CRD and STGD (18,20,32,33). Login to comment 119 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp WT and mutant constructs [L541P; A1038V], R602W and C1490Y ABCA4 were expressed in COS7 cells. Login to comment 131 ABCA4 p.Gly1961Glu ABCA4 p.Val2050Leu In subjects from five RP families (9% of disease alleles), we found heterozygous missense ABCA4 mutations (G1961E, V2050L, D2177 N and 36IVSþ1) that are suggested to have functional consequences for ABCA4 activity (29,36). Login to comment 136 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Arg602Trp ABCA4 p.Arg408* Co-segregating compound heterozygous mutant alleles (R602W/R408X) and a homozygous complex allele [L541P; A1038V] were identified in two (AR689 and AR197) arRP families (Table 1). Login to comment 137 ABCC7 p.Leu541Pro ABCA4 p.Ala1038Val ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp We hypothesized that the disease-associated missense mutations [L541P; A1038V], R602W and C1490Y could exert a possible effect on protein processing as this mechanism, which prevents altered proteins from locating to its physiologic compartment, was documented for other ABC transporters in related diseases including cystic fibrosis (CFTR) and Tangier disease (ABCA1). Login to comment 138 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp To examine this hypothesis, we generated transgenic X. laevis tadpoles expressing WT, [L541P; A1038V], R602W and C1490Y mutants and documented that the three mutant alleles cause mislocalization of ABCA4. Login to comment 146 ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Gly1961Glu ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Thr1019Met ABCA4 p.Thr1019Met ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Arg602Trp ABCA4 p.Leu2027Phe ABCA4 p.Leu2027Phe ABCA4 p.Leu2027Phe ABCA4 p.Leu2027Phe ABCA4 p.Leu2027Phe ABCA4 p.Leu2027Phe ABCA4 p.Leu2027Phe ABCA4 p.Pro1380Leu ABCA4 p.Arg1108His Genotype-phenotype correlations among patients bearing one and two mislocalization-mutations Two mislocalization-alleles One mislocalization-allele RP STGD Allele 1 Allele 2 AO Allele 1 Allele 2 AO [L541P; A1038V] [L541P; A1038V] 7 [L541P; A1038V] L2027F 13 [L541P; A1038V] [L541P; A1038V] 9 [L541P; A1038V] R1108H 13 [L541P; A1038V] G1961E 16 CRD [L541P; A1038V] G1961E 28 Allele 1 Allele 2 AO [L541P; A1038V] L2027F 13 [L541P; A1038V] [L541P; A1038V] 10 [L541P; A1038V] L2027F 12 [L541P; A1038V] C1490Y 12 [L541P; A1038V] P1380L 5 R602W R602W 7 [L541P; A1038V] T1019M 6 [L541P; A1038V] G1961E 7 STGD [L541P; A1038V] T1019M 6 Allele 1 Allele 2 AO R602W L2027F 9 [L541P; A1038V] [L541P; A1038V] 12 C1490Y G1961E 28 C1490Y C1490Y 7 C1490Y G1961E 13 C1490Y R602W 9 C1490Y L2027F 10 C1490Y R602W 10 C1490Y L2027F 18 C1490 L2027F 18 AO-age of onset (in years). Login to comment 150 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp The results of IF studies of rods expressing [L541P; A1038V], R602W and C1490Y mutants were quite distinct from those observed for WT and ABCA4 EGFP. Login to comment 152 ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro We also identified that L541P is responsible for the retention of the complex allele [L541P; A1038V], whereas A1038V seems to have no effect on ABCA4 processing. Login to comment 156 ABCA1 p.Arg587Trp Similar misfolding effects were observed for the analogous R587W mutation found in ABCA1 in patients with Tangier disease. Login to comment 157 ABCA1 p.Arg587Trp Experiments in which COS7 cells were transfected with a mutant ABCA1 construct, R587W, demonstrated the retention of the misfolded protein in the ER (39). Login to comment 164 ABCA4 p.Cys54Tyr ABCA4 p.Cys1488Tyr In addition, mutations of other cysteine residues from both ABCA4 ECDs have been identified in patients with retinal disease (C54Y, C1488Y) (12,18,41). Login to comment 165 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr Presumed folding mutations, especially [L541P; A1038V] and C1490Y, have been frequently detected in patients with autosomal recessive macular degenerations (18,20,32,33). Login to comment 179 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Arg602Trp Shown is a proposed topological model of ABCA4 with its membrane spanning domains and the mutations: L541P, R602W, A1038V and C1490 analyzed. Login to comment 199 ABCA4 p.Ala1038Val ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp To generate the retinal dystrophy associated ABCA4 alleles: [L541P; A1038V], L541P, A1038V, R602W and C1490Y ABCA4, the pXOP-ABCA4 plasmid was mutagenized with Quickchange PCR-based mutagenesis system (Biocrest, La Jolla, CA, USA). Login to comment 228 ABCA4 p.Ala1038Val ABCA4 p.Leu541Pro ABCA4 p.Cys1490Tyr ABCA4 p.Arg602Trp In particular, we searched for subjects with RP, CRD and STGD in whom two mislocalization-mutant alleles [L541P; A1038V], R602W and C1490Y] were detected. Login to comment