Calbindin-D(28k) controls [Ca2+](i) and insulin release. Evidence obtained from calbindin-D(28k) knockout mice and β cell lines

Karen Sooy, Thomas Schermerhorn, Mitsuhiko Noda, Manju Surana, William B. Rhoten, Michael Meyer, Norman Fleischer, Geoffrey W.G. Sharp, Sylvia Christakos

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99 Scopus citations

Abstract

The role of the calcium-binding protein, calbindin-D(28k) in potassium/depolarization-stimulated increases in the cytosolic free Ca2+ concentration ([Ca2+](i)) and insulin release was investigated in pancreatic islets from calbindin-D(28k) nullmutant mice (knockouts; KO) or wild type mice and β cell lines stably transfected and overexpressing calbindin. Using single islets from KO mice and stimulation with 45 mM KCl, the peak of [Ca2+](i) was 3.5-fold greater in islets from KO mice compared with wild type islets (p<0.01) and [Ca2+](i) remained higher during the plateau phase. In addition to the increase in [Ca2+](i) in response to KCl there was also a significant increase in insulin release in islets isolated from KO mice. Evidence for modulation by calbindin of [Ca2+](i) and insulin release was also noted using β cell lines. Rat calbindin was stably expressed in βTC-3 and βHC-13 cells. In response to depolarizing concentrations of K+, insulin release was decreased by 45-47% in calbindin expressing βTC cells and was decreased by 7080% in calbindin expressing βHC cells compared with insulin release from vector transfected βTC or βHC cells (p < 0.01). In addition, the K+-stimulated intracellular calcium peak was markedly inhibited in calbindin expressing βHC cells compared with vector transfected cells (225 nM versus 1,100 nM, respectively). Buffering of the depolarization-induced rise in [Ca2+](i) was also observed in calbindin expressing βTC cells. In summary, our findings, using both isolated islets from calbindin-D(28k) KO mice and β cell lines, establish a role for calbindin in the modulation of depolarization-stimulated insulin release and suggest that calbindin can control the rate of insulin release via regulation of [Ca2+](i).

Original languageEnglish (US)
Pages (from-to)34343-34349
Number of pages7
JournalJournal of Biological Chemistry
Volume274
Issue number48
DOIs
StatePublished - Nov 26 1999

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Sooy, K., Schermerhorn, T., Noda, M., Surana, M., Rhoten, W. B., Meyer, M., Fleischer, N., Sharp, G. W. G., & Christakos, S. (1999). Calbindin-D(28k) controls [Ca2+](i) and insulin release. Evidence obtained from calbindin-D(28k) knockout mice and β cell lines. Journal of Biological Chemistry, 274(48), 34343-34349. https://doi.org/10.1074/jbc.274.48.34343