Suppression of Sulfonylurea- and Glucose-Induced Insulin Secretion In Vitro and In Vivo in Mice Lacking the Chloride Transport Protein ClC-3

• Published in: Cell metabolism Vol. 10; no. 4; pp. 309 - 315
• Main Authors: Li, Dai-Qing, Jing, Xingjun, Salehi, Albert, Collins, Stephan C., Hoppa, Michael B., Rosengren, Anders H., Zhang, Enming, Lundquist, Ingmar, Olofsson, Charlotta S., Mörgelin, Matthias, Eliasson, Lena, Rorsman, Patrik, Renström, Erik
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2009
• Subjects: Animals; Basic Medicine; Calcium; Calcium - metabolism; Cell and Molecular Biology; Cell- och molekylärbiologi; CELLBIO; Chloride Channels; Chloride Channels - genetics; Chloride Channels - metabolism; Chlorides; Chlorides - metabolism; cytology; Cytoplasmic Granules; Cytoplasmic Granules - metabolism; drug effects; Fysiologi; genetics; Glucagon-Like Peptide 1; Glucagon-Like Peptide 1 - metabolism; Glucose; Glucose - metabolism; HUMDISEASE; Insulin; Insulin - metabolism; Insulin Secretion; Insulin-Secreting Cells; Insulin-Secreting Cells - cytology; Insulin-Secreting Cells - drug effects; Insulin-Secreting Cells - metabolism; Knockout; Medical and Health Sciences; Medicin och hälsovetenskap; Medicinska och farmaceutiska grundvetenskaper; metabolism; Mice; Mice, Knockout; pharmacology; Physiology; RNA Interference; secretion; Sulfonylurea Compounds; Sulfonylurea Compounds - pharmacology; CELLBIO; HUMDISEASE
• ISSN: 1550-4131; 1932-7420; 1932-7420
• DOI: 10.1016/j.cmet.2009.08.011

Priming of insulin secretory granules for release requires intragranular acidification and depends on vesicular Cl −-fluxes, but the identity of the chloride transporter/ion channel involved is unknown. We tested the hypothesis that the chloride transport protein ClC-3 fulfills these actions in pancreatic β cells. In ClC-3 −/− mice, insulin secretion evoked by membrane depolarization (high extracellular K +, sulfonylureas), or glucose was >60% reduced compared to WT animals. This effect was mirrored by a ∼80% reduction in depolarization-evoked β cell exocytosis (monitored as increases in cell capacitance) in single ClC-3 −/− β cells, as well as a 44% reduction in proton transport across the granule membrane. ClC-3 expression in the insulin granule was demonstrated by immunoblotting, immunostaining, and negative immuno-EM in a high-purification fraction of large dense-core vesicles (LDCVs) obtained by phogrin-EGFP labeling. The data establish the importance of granular Cl − fluxes in granule priming and provide direct evidence for the involvement of ClC-3 in the process.