title: Increased Slc12a1 expression in β-cells and improved glucose disposal in Slc12a2 heterozygous mice.
abstract: The products of the Slc12a1 and Slc12a2 genes, commonly known as Na(+)-dependent K(+)2Cl(-) co-transporters NKCC2 and NKCC1, respectively, are the targets for the diuretic bumetanide. NKCCs are implicated in the regulation of intracellular chloride concentration ([Cl(-)]i) in pancreatic β-cells, and as such, they may play a role in glucose-stimulated plasma membrane depolarization and insulin secretion. Unexpectedly, permanent elimination of NKCC1 does not preclude insulin secretion, an event potentially linked to the homeostatic regulation of additional Cl(-) transporters expressed in β-cells. In this report we provide evidence for such a mechanism. Mice lacking a single allele of Slc12a2 exhibit lower fasting glycemia, increased acute insulin response (AIR) and lower blood glucose levels 15-30 min after a glucose load when compared to mice harboring both alleles of the gene. Furthermore, heterozygous expression or complete absence of Slc12a2 associates with increased NKCC2 protein expression in rodent pancreatic β-cells. This has been confirmed by using chronic pharmacological down-regulation of NKCC1 with bumetanide in the mouse MIN6 β-cell line or permanent molecular silencing of NKCC1 in COS7 cells, which results in increased NKCC2 expression. Furthermore, MIN6 cells chronically pretreated with bumetanide exhibit increased initial rates of Cl(-) uptake while preserving glucose-stimulated insulin secretion. Together, our results suggest that NKCCs are involved in insulin secretion and that a single Slc12a2 allele may protect β-cells from failure due to increased homeostatic expression of Slc12a1.
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA.
authors.forename: Saeed
authors.initials: S
authors.lastname: Alshahrani
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA.
authors.forename: Mohammed Mashari
authors.initials: MM
authors.lastname: Almutairi
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA.
authors.forename: Shams
authors.initials: S
authors.lastname: Kursan
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Dias-Junior
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA.
authors.forename: Mohamed Mahmoud
authors.initials: MM
authors.lastname: Almiahuob
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA.
authors.forename: Lydia
authors.initials: L
authors.lastname: Aguilar-Bryan
authors.affiliation: Department of Pharmacology and ToxicologyBoonshoft School of Medicine, Wright State University, 3640 Colonel Glenn Highway, 216 HSB, Dayton, Ohio 45435, USAPacific Northwest Diabetes Research InstituteSeattle, Washington 98122, USA Mauricio.DiFulvio@wright.edu.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Di Fulvio
mesh_terms: D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006579:Heterozygote; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D064466:Solute Carrier Family 12, Member 1 / Q000235:genetics / Q000378:metabolism*; D064506:Solute Carrier Family 12, Member 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D007328:Insulin; D049994:Sodium Potassium Chloride Symporter Inhibitors; D064466:Solute Carrier Family 12, Member 1; D064506:Solute Carrier Family 12, Member 2; D002034:Bumetanide; D005947:Glucose
keywords: NKCC1; NKCC2; glucose homeostasis; insulin secretion; β-cell