Sulfonylureas correct trafficking defects of ATP-sensitive potassium channels caused by mutations in the sulfonylurea receptor.
The pancreatic ATP-sensitive potassium (K(ATP)) channel, a complex of four sulfonylurea receptor 1 (SUR1) and four potassium channel Kir6.2 subunits, regulates insulin secretion by linking metabolic changes to beta-cell membrane potential. Sulfonylureas inhibit K(ATP) channel activities by binding to SUR1 and are widely used to treat type II diabetes. We report here that sulfonylureas also function as chemical chaperones to rescue K(ATP) channel trafficking defects caused by two SUR1 mutations, A116P and V187D, identified in patients with congenital hyperinsulinism. Sulfonylureas markedly increased cell surface expression of the A116P and V187D mutants by stabilizing the mutant SUR1 proteins and promoting their maturation. By contrast, diazoxide, a potassium channel opener that also binds SUR1, had no effect on surface expression of either mutant. Importantly, both mutant channels rescued to the cell surface have normal ATP, MgADP, and diazoxide sensitivities, demonstrating that SUR1 harboring either the A116P or the V187D mutation is capable of associating with Kir6.2 to form functional K(ATP) channels. Thus, sulfonylureas may be used to treat congenital hyperinsulinism caused by certain K(ATP) channel trafficking mutations.
Yan
Feifei
F
Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, Oregon 97239, USA.
Lin
Chia-Wei
CW
Weisiger
Elizabeth
E
Cartier
Etienne A
EA
Taschenberger
Grit
G
Shyng
Show-Ling
SL
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D019556:COS Cells; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D017136:Ion Transport; D008163:Luminescent Measurements; D009154:Mutation; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D013453:Sulfonylurea Compounds / Q000494:pharmacology*
D015221:Potassium Channels; D013453:Sulfonylurea Compounds; D000255:Adenosine Triphosphate; D005905:Glyburide