ABCMdb

PMID: 17575084

Yan FF, Lin YW, MacMullen C, Ganguly A, Stanley CA, Shyng SL
Congenital hyperinsulinism associated ABCC8 mutations that cause defective trafficking of ATP-sensitive K+ channels: identification and rescue.
Diabetes. 2007 Sep;56(9):2339-48. Epub 2007 Jun 15., [PubMed]

Sentences

No. Mutations Sentence Comment

47 ABCC8 p.Gly716Val ABCC8 p.Gly716Val ABCC8 p.Gly716Val ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser ABCC8 p.Phe27Ser ABCC8 p.Phe686Ser ABCC8 p.Phe686Ser ABCC8 p.Glu501Lys ABCC8 p.Glu501Lys ABCC8 p.Leu503Pro ABCC8 p.Leu503Pro ABCC8 p.Arg495Gln ABCC8 p.Arg495Gln TABLE 1 Genetic and clinical information on patients carrying the CHI mutations Mutation Disease Haplotype Diazoxide response References G7R Focal G7R No 44 N24K Diffuse N24K/R1215W No Not reported F27S Focal F27S No 39 R74W Focal R74W/R1215Q No 39,45,46 E128K Diffuse E128K No Not reported R495Q Diffuse R495Q/R1215Q No 39 E501K Focal E501K No 39 L503P Focal L503P No 44 F686S Focal F686S No 39 G716V* Diffuse G716V/G716V No 47,48 K1337N Not done g3992-9a/K1337N Yes 39 L1350Q Focal L1350Q No 44 S1387F Diffuse S1387F/NA No 9,24 L1390P NA L1390P/NA No Not reported D1472H Diffuse ⌬F1388/D1472H No 39 *Patient was from consanguineous mating and therefore was homozygous for the G716V mutation (48). Login to comment 48 ABCC8 p.Gly716Val ABCC8 p.Gly716Val ABCC8 p.Gly716Val ABCC8 p.Glu128Lys ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser ABCC8 p.Phe27Ser ABCC8 p.Phe686Ser ABCC8 p.Phe686Ser ABCC8 p.Glu501Lys ABCC8 p.Glu501Lys ABCC8 p.Leu503Pro ABCC8 p.Leu503Pro ABCC8 p.Arg495Gln ABCC8 p.Arg495Gln TABLE 1 Genetic and clinical information on patients carrying the CHI mutations Mutation Disease Haplotype Diazoxide response References G7R Focal G7R No 44 N24K Diffuse N24K/R1215W No Not reported F27S Focal F27S No 39 R74W Focal R74W/R1215Q No 39,45,46 E128K Diffuse E128K No Not reported R495Q Diffuse R495Q/R1215Q No 39 E501K Focal E501K No 39 L503P Focal L503P No 44 F686S Focal F686S No 39 G716V* Diffuse G716V/G716V No 47,48 K1337N Not done g3992-9a/K1337N Yes 39 L1350Q Focal L1350Q No 44 S1387F Diffuse S1387F/NA No 9,24 L1390P NA L1390P/NA No Not reported D1472H Diffuse èc;F1388/D1472H No 39 *Patient was from consanguineous mating and therefore was homozygous for the G716V mutation (48). Login to comment 94 ABCC8 p.Gly716Val ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser ABCC8 p.Phe686Ser ABCC8 p.Glu501Lys ABCC8 p.Leu503Pro ABCC8 p.Arg495Gln The first group, including G7R, N24K, F27S, R74W, and E128K, is located in the first transmembrane domain TMD0; the second group, including R495Q, E501K, L503P, F686S, and G716V, is located in the second transmembrane domain TMD1 extending through the first nucleotide binding domain; the third group, including K1337N, L1350Q, S1387F, L1390P, and D1472H, is clustered in the second nucleotide binding domain and the COOH terminus of the protein. Login to comment 95 ABCC8 p.Gly716Val ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser ABCC8 p.Phe686Ser ABCC8 p.Glu501Lys ABCC8 p.Leu503Pro ABCC8 p.Arg495Gln The first group, including G7R, N24K, F27S, R74W, and E128K, is located in the first transmembrane domain TMD0; the second group, including R495Q, E501K, L503P, F686S, and G716V, is located in the second transmembrane domain TMD1 extending through the first nucleotide binding domain; the third group, including K1337N, L1350Q, S1387F, L1390P, and D1472H, is clustered in the second nucleotide binding domain and the COOH terminus of the protein. Login to comment 102 ABCC8 p.Glu128Lys ABCC8 p.Asn24Lys The mutations that have not been previously reported in the literature include N24K, E128K, and L1390P. Login to comment 103 ABCC8 p.Glu128Lys ABCC8 p.Asn24Lys The mutations that have not been previously reported in the literature include N24K, E128K, and L1390P. Login to comment 118 ABCC8 p.Gly716Val ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser ABCC8 p.Phe686Ser ABCC8 p.Glu501Lys ABCC8 p.Leu503Pro ABCC8 p.Arg495Gln Results from this assay showed that F27S, R74W, E128K, R495Q, E501K, L503P, F686S, G716V, L1350Q, and D1472H mutant channels had greatly reduced surface expression (Ͻ20% of wild-type level)-whereas G7R and N24K mutant channels displayed modestly decreased surface expression level (Ͼ30% but Ͻ50% of wild-type level) and K1337N, S1378F, and L1390P exhibited normal or mildly reduced expression (Ͼ60% of wild-type level; Fig. 3A). Login to comment 119 ABCC8 p.Gly716Val ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser ABCC8 p.Phe686Ser ABCC8 p.Glu501Lys ABCC8 p.Leu503Pro ABCC8 p.Arg495Gln Results from this assay showed that F27S, R74W, E128K, R495Q, E501K, L503P, F686S, G716V, L1350Q, and D1472H mutant channels had greatly reduced surface expression (b0d;20% of wild-type level)-whereas G7R and N24K mutant channels displayed modestly decreased surface expression level (b0e;30% but b0d;50% of wild-type level) and K1337N, S1378F, and L1390P exhibited normal or mildly reduced expression (b0e;60% of wild-type level; Fig. 3A). Login to comment 129 ABCC8 p.Val187Asp ABCC8 p.Ala116Pro We first examined the effects of sulfonylureas, which were shown previously to improve surface expression of the A116P- and V187D-SUR1 mutants (16), on the trafficking mutants identified in this study (those that had surface expression Ͻ50% of wild type based on chemiluminescence assays shown in Fig. 3A). Login to comment 130 ABCC8 p.Glu128Lys ABCC8 p.Arg74Trp ABCC8 p.Asn24Lys ABCC8 p.Phe27Ser In Western blots, several mutants, including G7R, N24K, F27S, R74W, and E128K, all located in TMD0, exhibited increased complex-glycosylated SUR1 in cells coexpressing Kir6.2 on overnight treatment with 1 ␮mol/l glibenclamide (Fig. 5A). Login to comment 140 ABCC8 p.Ala116Pro To ensure that the trafficking defects of TMD0 mutations and their rescue by sulfonylureas are also seen in a cellular environment in which the channels normally reside, we examined whether A116P, a TMD0 trafficking mutant we documented previously, behaves the same in the insulin-secreting cell line INS-1 as in COS cells. Login to comment 142 ABCC8 p.Ala116Pro As shown in Fig. 5D, A116P-SUR1 expressed in INS-1 cells failed to mature into the complex-glycosylated form; however, overnight treatment of cells with 1 ␮mol/l glibenclamide overcame this processing defect and led to the appearance of the complex-glycosylated form. Login to comment 143 ABCC8 p.Ala116Pro These observations recapitulate what we have reported previously for A116P-SUR1 expressed in COS cells (16), FIG. 5. Login to comment 150 ABCC8 p.Ala116Pro D: Western blot showing that the A116P-SUR1 expressed in INS-1 cells lacks the complex-glycosylated band and that treatment of cells with glibenclamide led to appearance of the complex-glycosylated band, as observed in COS cells. Login to comment 177 ABCC8 p.Val187Asp ABCC8 p.Ala116Pro The first two trafficking mutations that we reported to be rescued by sulfonylurea drugs are A116P and V187D, both located in TMD0 of SUR1 (16). Login to comment 178 ABCC8 p.Val187Asp ABCC8 p.Ala116Pro The first two trafficking mutations that we reported to be rescued by sulfonylurea drugs are A116P and V187D, both located in TMD0 of SUR1 (16). Login to comment 183 ABCC8 p.Val187Asp ABCC8 p.Ala116Pro First, a truncated SUR1 of TMD0 alone containing the A116P or V187D trafficking mutations failed to respond to sulfonylurea rescue. Login to comment 184 ABCC8 p.Val187Asp ABCC8 p.Ala116Pro ABCC8 p.Tyr230Ala First, a truncated SUR1 of TMD0 alone containing the A116P or V187D trafficking mutations failed to respond to sulfonylurea rescue. Login to comment 185 ABCC8 p.Tyr230Ala Second, two point mutations, Y230A and S1238Y, that are located downstream of TMD0 and are known to diminish or abolish glibenclamide and tolbutamide binding accordingly affected the ability of the drugs to rescue channel trafficking defects caused by TMD0 mutations (31,36,37). Login to comment 202 ABCC8 p.Arg74Trp ABCC8 p.Arg495Gln For example, both R74W and R495Q are compound heterozygous mutations with R1215Q. Login to comment 203 ABCC8 p.Arg74Trp ABCC8 p.Arg74Trp ABCC8 p.Arg495Gln ABCC8 p.Arg495Gln For example, both R74W and R495Q are compound heterozygous mutations with R1215Q. Login to comment 204 ABCC8 p.Arg74Trp ABCC8 p.Arg495Gln Based on in vitro functional phenotypes of mutant hamster SUR1/rat Kir6.2 channels expressed in COS cells, one would expect that in patients, in addition to the expression defects caused by the R74W or R495Q mutation, the R1215Q mutation would also reduce channel function by reducing channel response to MgADP (28). Login to comment 207 ABCC8 p.Arg74Trp This was particularly the case in a patient with compound heterozygous R74W/R1215Q mutations who had a greater than normal insulin response to tolbutamide. Login to comment 209 ABCC8 p.Arg74Trp This was particularly the case in a patient with compound heterozygous R74W/R1215Q mutations who had a greater than normal insulin response to tolbutamide. Login to comment 212 ABCC8 p.Ala116Pro Because there are many examples of cell-type-specific protein trafficking regulation (13,21,43), what we found in COS cells may not extrapolate directly to beta-cells. In this regard, our results that a previously published TMD0 trafficking mutant, A116P, exhibits the same trafficking defect and response to sulfonylurea rescue in INS-1 cells as in COS cells provide some assurance that the TMD0 mutants are likely to behave similarly in their native environment. Login to comment 214 ABCC8 p.Ala116Pro Because there are many examples of cell-type-specific protein trafficking regulation (13,21,43), what we found in COS cells may not extrapolate directly to beta-cells. In this regard, our results that a previously published TMD0 trafficking mutant, A116P, exhibits the same trafficking defect and response to sulfonylurea rescue in INS-1 cells as in COS cells provide some assurance that the TMD0 mutants are likely to behave similarly in their native environment. Login to comment