| First Author | Solomou A | Year | 2015 |
| Journal | J Biol Chem | Volume | 290 |
| Issue | 35 | Pages | 21432-42 |
| PubMed ID | 26178371 | Mgi Jnum | J:225498 |
| Mgi Id | MGI:5693441 | Doi | 10.1074/jbc.M115.645291 |
| Citation | Solomou A, et al. (2015) The Zinc Transporter Slc30a8/ZnT8 Is Required in a Subpopulation of Pancreatic alpha-Cells for Hypoglycemia-induced Glucagon Secretion. J Biol Chem 290(35):21432-42 |
| abstractText | SLC30A8 encodes a zinc transporter ZnT8 largely restricted to pancreatic islet beta- and alpha-cells, and responsible for zinc accumulation into secretory granules. Although common SLC30A8 variants, believed to reduce ZnT8 activity, increase type 2 diabetes risk in humans, rare inactivating mutations are protective. To investigate the role of Slc30a8 in the control of glucagon secretion, Slc30a8 was inactivated selectively in alpha-cells by crossing mice with alleles floxed at exon 1 to animals expressing Cre recombinase under the pre-proglucagon promoter. Further crossing to Rosa26:tdRFP mice, and sorting of RFP(+): glucagon(+) cells from KO mice, revealed recombination in approximately 30% of alpha-cells, of which approximately 50% were ZnT8-negative (14 +/- 1.8% of all alpha-cells). Although glucose and insulin tolerance were normal, female alphaZnT8KO mice required lower glucose infusion rates during hypoglycemic clamps and displayed enhanced glucagon release (p < 0.001) versus WT mice. Correspondingly, islets isolated from alphaZnT8KO mice secreted more glucagon at 1 mm glucose, but not 17 mm glucose, than WT controls (n = 5; p = 0.008). Although the expression of other ZnT family members was unchanged, cytoplasmic (n = 4 mice per genotype; p < 0.0001) and granular (n = 3, p < 0.01) free Zn(2+) levels were significantly lower in KO alpha-cells versus control cells. In response to low glucose, the amplitude and frequency of intracellular Ca(2+) increases were unchanged in alpha-cells of alphaZnT8KO KO mice. ZnT8 is thus important in a subset of alpha-cells for normal responses to hypoglycemia and acts via Ca(2+)-independent mechanisms. |
