ABCMdb

PMID: 18390792

Abdulhadi-Atwan M, Bushman J, Tornovsky-Babaey S, Perry A, Abu-Libdeh A, Glaser B, Shyng SL, Zangen DH
Novel de novo mutation in sulfonylurea receptor 1 presenting as hyperinsulinism in infancy followed by overt diabetes in early adolescence.
Diabetes. 2008 Jul;57(7):1935-40. Epub 2008 Apr 4., [PubMed]

Sentences

No. Mutations Sentence Comment

7 ABCC8 p.Arg370Ser RESULTS-A novel, de novo heterozygous ABCC8 sulfonylurea receptor (SUR)1 mutation (R370S) was identified in the patient`s DNA but not in that of either parent. Login to comment 20 ABCC8 p.Arg370Ser Here we report a novel, de novo heterozygous mutation in the SUR1 gene (ABCC8) (R370S) causing CHI in early infancy followed by overt diabetes presenting at age 10.5 years, suggesting that this mutation facilitates the development of early-onset nonautoimmune diabetes. Login to comment 56 ABCC8 p.Arg370Ser The R370S point mutation of SUR1 was introduced into hamster SUR1 cDNA in the pECE plasmid using the QuikChange site-directed mutagenesis kit (Stratagene). Login to comment 89 ABCC8 p.Arg370Ser A novel heterozygous missense mutation was detected in exon 7 of ABCC8 (AGG3AGC at the 1,111 nucleotide position) (Fig. 2A), predicting an arginine to serine mutation at the 370th amino acid of the SUR1 protein (R370S). Login to comment 95 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser Cotransfection of Kir6.2 and mutant SUR1 (SUR1- R370S) in COSm6 cells demonstrated normal channel expression on the cell membrane (Fig. 3A). Login to comment 109 ABCC8 p.Arg370Ser DISCUSSION Here, we report a patient with a de novo heterozygous mutation in the SUR1 gene (R370S) resulting in congenital A No treatment Repaglinide Postprandial time (min) Glucose(mmol/l) Fasting 2hr after breakfast 2hr after lunch 2hr after dinner Glucose(mmol/l) No treatment Glibenclamide D Glucose(mmol/l) Time of Day 10/06/200609/06/2006 Time of Day B Glucose(mmol/l) * * * * * Time (min) Insulin(pmoI/l) Glucose Insulin Glucose No treatment Repaglinide C FIG. 1. Login to comment 118 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser Wild type Mutant BA R370S ABCC8 Proband Sequence T G C A A A C A T T TA G G A G C FIG. 2. Login to comment 119 ABCC8 p.Arg370Ser The R370S mutation. Login to comment 126 ABCC8 p.Arg370Ser Although the amino acid location of the R370S mutation could not predict its dominant effect, we demonstrated normal membrane expression, a finding common to previously reported dominant SUR1 gene mutations (16,19). Login to comment 127 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser As the KATP channel is a hetero-octamer containing four SUR1 subunits, a normally processed and translocated heterozygous mutant SUR1 0 10 20 30 40 50 60 70 80 90 100 0.1 mM ATP 0.1 mM ATP/0.5mM ADP %Current 0 1000 2000 3000 4000 5000 6000 unt WT R370S 0 10 20 30 40 50 60 70 80 90 100 WT WT:R370S R370S WT WT:R370S R370S WT WT:R370S R370S 0.1 mM ATP 0.1mM ATP/0.3mM Diazoxide 0 10 20 30 40 50 60 70 80 90 100 10 nM Glib 100 nM Glib 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 Untr R370S WT R370S:WT WT+Glib R370S+Glib %Efflux Time (min) %Current %Current 10s WT R370S WT R370S WT R370S WT R370S 1 mM ATP 0.1 mM ATP 0.1 mM ATP+ 0.5 mM ADP 1 mM ATP 0.1 mM ATP 0.1 mM ATP+ 0.3 mM Diaz 1 mM ATP 10nM Glibenclamide Relative chemiluminescenceunits A B C D E F G H 10s 0.5nA 10s 1nA 10s 10s 1nA0.5nA 20s 1nA 20s 1nA unt R370SWT FIG. 3. Login to comment 129 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser COS cells were untransfected (unt) or transiently transfected with Kir6.2 and SUR1 of WT, R370S, or WT and R370S at 1:1 equal molar cDNA ratio (WT:R370S) and subjected to various expression and functional analyses. Login to comment 131 ABCC8 p.Arg370Ser The relative chemiluminescence units of untransfected, WT, and R370S samples are 234 ؎ 8 (n ‫؍‬ 11), 4,788 ؎ 509 (n ‫؍‬ 14), and 4,736 ؎ 485 (n ‫؍‬ 15), respectively. Login to comment 132 ABCC8 p.Arg370Ser The WT and R370S expression levels are not significantly different (P > 0.5). Login to comment 135 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser Cells expressing the R370S mutant had near background flux levels, and cells expressing a mixture of WT and R370S showed intermediate flux level between WT and the mutant. Login to comment 136 ABCC8 p.Arg370Ser C: Representative current traces of WT and R370S channels in response to MgADP stimulation obtained by inside-out patch clamp recording. Login to comment 140 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser In 0.1 mmol/l ATP/0.5 mmol/l ADP, the percent current of WT, WT:R370S, and R370S was 64.3 ؎ 7.9 (n ‫؍‬ 10), 23.4 ؎ 4.7 (n ‫؍‬ 6), and 5.4 ؎ 2.3 (n ‫؍‬ 7), respectively; the values of both WT:R370S and R370S are significantly lower than that of WT (P < 0.05 and 0.005, respectively). Login to comment 142 ABCC8 p.Arg370Ser The percent current in 0.1 mmol/l ATP/0.3 mmol/l diazoxide for WT, WT:R370S, and R370S was 43.0 ؎ 5.2, 22.8 ؎ 3.0, and 3.9 ؎ 1.0, respectively. Login to comment 147 ABCC8 p.Arg370Ser ABCC8 p.Arg370Ser The percent current in 10 nmol/l glibenclamide was 53.3 ؎ 6.0 (n ‫؍‬ 8), 70.6 ؎ 8.1 (n ‫؍‬ 4), and 55.4 ؎ 4.8 (n ‫؍‬ 5) for WT, WT:R370S, and R370S, respectively; these values are not significantly different (P > 0.1). Login to comment 149 ABCC8 p.Arg370Ser subunit such as R370S would be expected to be present in 15 of 16 of the channels on the membrane and thus may alter their function. Login to comment 152 ABCC8 p.Glu1506Lys ABCC8 p.Glu1506Lys Huopio and coworkers (11,12) reported a dominant inactivating ABCC8 mutation, E1506K, that caused hyperinsulinemic hypoglycemia followed by hypoinsulinemic diabetes; however, when compared with our patient, nonpancreatectomized E1506K patients in whom overt diabetes presented later, during middle age, had mild neonatal hypoglycemia. Login to comment 158 ABCC8 p.Arg370Ser Our data in COS cells suggest equal biogenesis efficiency (data not shown) and surface expression of the WT and mutant R370S proteins at the plasma membrane. Login to comment 174 ABCC8 p.Arg370Ser However, the surprising response of the mutated R370S KATP channel to sulfonylureas in vitro suggested the use of these medications for glycemic control. The good response to glibenclamide enabled our patient to be treated with oral medications rather than insulin injections, a significant advantage given her poor compliance. Login to comment 181 ABCC8 p.Arg370Ser Our findings suggest a critical role for the ABCC8 R370S mutation in the early presentation of diabetes in this patient. Login to comment