Inhibition of Kv2.1 Voltage-dependent K+Channels in Pancreatic β-Cells Enhances Glucose-dependent Insulin Secretion
Voltage-dependent (Kv) outward K + currents repolarize β-cell action potentials during a glucose stimulus to limit Ca 2+ entry and insulin secretion. Dominant-negative âknockoutâ of Kv2 family channels enhances glucose-stimulated insulin secretion. Here we show that a putative Kv2.1 antagonist...
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Published in | The Journal of biological chemistry Vol. 277; no. 47; p. 44938 |
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Main Authors | , , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society for Biochemistry and Molecular Biology
22.11.2002
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Online Access | Get full text |
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Summary: | Voltage-dependent (Kv) outward K + currents repolarize β-cell action potentials during a glucose stimulus to limit Ca 2+ entry and insulin secretion. Dominant-negative âknockoutâ of Kv2 family channels enhances glucose-stimulated insulin secretion.
Here we show that a putative Kv2.1 antagonist (C-1) stimulates insulin secretion from MIN6 insulinoma cells in a glucose-
and dose-dependent manner while blocking voltage-dependent outward K + currents. C-1-blocked recombinant Kv2.1-mediated currents more specifically than currents mediated by Kv1, -3, and -4 family
channels (Kv1.4, 3.1, 4.2). Additionally, C-1 had little effect on currents recorded from MIN6 cells expressing a dominant-negative
Kv2.1 α-subunit. The insulinotropic effect of acute Kv2.1 inhibition resulted from enhanced membrane depolarization and augmented
intracellular Ca 2+ responses to glucose. Immunohistochemical staining of mouse pancreas sections showed that expression of Kv2.1 correlated
highly with insulin-containing β-cells, consistent with the ability of C-1 to block voltage-dependent outward K + currents in isolated mouse β-cells. Antagonism of Kv2.1 in an ex vivo perfused mouse pancreas model enhanced first- and second-phase insulin secretion, whereas glucagon secretion was unaffected.
The present study demonstrates that Kv2.1 is an important component of β-cell stimulus-secretion coupling, and a compound
that enhances, but does not initiate, β-cell electrical activity by acting on Kv2.1 would be a useful antidiabetic agent. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M205532200 |