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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Johnson, James D. Misler, Stanley |
| Description | Author Affiliation: Johnson JD ( Department of Internal Medicine, Renal Division, Barnes-Jewish Hospital, St. Louis, MO 63110, USA. jim@jimjohnson.ca); |
| Abstract | Recent studies suggest a role for autocrine insulin signaling in beta cells, but the mechanism and function of insulin-stimulated Ca(2+) signals is uncharacterized. We examined Ca(2+)-dependent insulin signaling in human beta cells. Two hundred nanomolar insulin elevated [Ca(2+)](c) to 284 +/- 27 nM above baseline in approximately 30% of Fura-4F-loaded cells. Insulin evoked multiple Ca(2+) signal waveforms, 60% of which included oscillations. Although the amplitude of Ca(2+) signals was dose-dependent between 0.002 and 2,000 nM, the percentage of cells responding was highest at 0.2 nM insulin, suggesting the interaction of stimulatory and inhibitory pathways. Ca(2+)-free solutions did not affect the initiation of insulin-stimulated Ca(2+) signals, but abolished the second phase of plateaus/oscillations. Likewise, inositol 1,4,5-trisphosphate (IP(3)) receptor antagonists xestospongin C and caffeine selectively blocked the second phase, but not the initiation of insulin signaling. Thapsigargin and 2,5-di-tert-butylhydroquinone (BHQ) blocked insulin signaling, implicating sarcoplasmic/endoplasmic Ca(2+)-ATPase (SERCA)-containing Ca(2+) stores. Insulin-stimulated Ca(2+) signals were insensitive to ryanodine. Injection of the CD38-derived Ca(2+) mobilizing metabolite, nicotinic acid-adenine dinucleotide phosphate (NAADP), at nanomolar concentrations, evoked oscillatory Ca(2+) signals that could be initiated in the presence of ryanodine, xestospongin C, and Ca(2+)-free solutions. Desensitizing concentrations of NAADP abolished insulin-stimulated Ca(2+) signals. Insulin-stimulated Ca(2+) signals led to a Ca(2+)-dependent increase in cellular insulin contents, but not secretion. These data reveal the complexity of insulin signal transduction and function in human beta cells and demonstrate functional NAADP-sensitive Ca(2+) stores in a human primary cultured cell type. |
| ISSN | 00278424 |
| e-ISSN | 10916490 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Issue Number | 22 |
| Volume Number | 99 |
| Language | English |
| Publisher | National Academy of Sciences |
| Publisher Date | 2002-10-01 |
| Publisher Place | United States |
| Access Restriction | Open |
| Subject Keyword | Calcium Signaling Drug Effects Insulin Metabolism Islets Of Langerhans NADP Analogs & Derivatives Pharmacology Caffeine Calcium Channels Calcium-Transporting ATPases Antagonists & Inhibitors Cells, Cultured Electrophysiology Hydroquinones Inositol 1,4,5-Trisphosphate Receptors Intracellular Fluid Macrocyclic Compounds Oxazoles Receptors, Cytoplasmic And Nuclear Thapsigargin Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. Multidisciplinary |
| Content Type | Text |
| Resource Type | Article |
| Subject | Multidisciplinary |
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