Down-regulation of ZnT8 expression in INS-1 rat pancreatic beta cells reduces insulin content and glucose-inducible insulin secretion

• Published in: PloS one 2009-05, Vol.4 (5), p.e5679
• Main Authors: Fu, Yi, Tian, Wei, Pratt, Emily B, Dirling, Lisa B, Shyng, Show-Ling, Meshul, Charles K, Cohen, David M
• Format: Article
• Language: English
• Subjects: Adipocytes; Animals; Beta cells; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Dense core vesicles; Departments; Developmental biology; Diabetes; Diabetes and Endocrinology/Type 2 Diabetes; Diabetes mellitus; Disease susceptibility; Down-Regulation - drug effects; Electron microscopy; Fluorescence; Gene expression; Gene Knockdown Techniques; Gene polymorphism; Genetic aspects; Genetic polymorphisms; Genomes; Glucose; Glucose - pharmacology; Homeostasis; Hyperglycemia; Hypertension; Immunoassay; Insulin; Insulin - metabolism; Insulin Secretion; Insulin-Secreting Cells - cytology; Insulin-Secreting Cells - drug effects; Insulin-Secreting Cells - metabolism; Insulin-Secreting Cells - ultrastructure; Intracellular Space - drug effects; Intracellular Space - metabolism; Intracellular Space - ultrastructure; Journalistic ethics; Metabolism; Nephrology; Nephrology/Chronic Kidney Disease; Neurosciences; Nickel - pharmacology; Pancreas; Pancreatic beta cells; Physiology; Physiology/Endocrinology; Polymorphism; Proteins; Quinolones - metabolism; Rats; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Small Interfering - metabolism; Rodents; Science; Secretory Vesicles - drug effects; Secretory Vesicles - metabolism; Secretory Vesicles - ultrastructure; Tosyl Compounds - metabolism; Trace elements; Transporter; Type 2 diabetes; Zinc; Zinc - metabolism; Zinc - pharmacology; Zinc transporter; Zinc Transporter 8
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0005679

The SLC30A8 gene codes for a pancreatic beta-cell-expressed zinc transporter, ZnT8. A polymorphism in the SLC30A8 gene is associated with susceptibility to type 2 diabetes, although the molecular mechanism through which this phenotype is manifest is incompletely understood. Such polymorphisms may exert their effect via impacting expression level of the gene product. We used an shRNA-mediated approach to reproducibly downregulate ZnT8 mRNA expression by >90% in the INS-1 pancreatic beta cell line. The ZnT8-downregulated cells exhibited diminished uptake of exogenous zinc, as determined using the zinc-sensitive reporter dye, zinquin. ZnT8-downregulated cells showed reduced insulin content and decreased insulin secretion (expressed as percent of total insulin content) in response to hyperglycemic stimulus, as determined by insulin immunoassay. ZnT8-depleted cells also showed fewer dense-core vesicles via electron microscopy. These data indicate that reduced ZnT8 expression in cultured pancreatic beta cells gives rise to a reduced insulin response to hyperglycemia. In addition, although we provide no direct evidence, these data suggest that an SLC30A8 expression-level polymorphism could affect insulin secretion and the glycemic response in vivo.