Mechanisms of integrin-mediated calcium signaling in MDCK cells: regulation of adhesion by IP3- and store-independent calcium influx
| Autor: | Michael D. Sjaastad, W J Nelson, Richard S. Lewis |
|---|---|
| Rok vydání: | 1996 |
| Předmět: |
Integrins
Thapsigargin chemistry.chemical_element Inositol 1 4 5-Trisphosphate Biology Calcium Cell Line Feedback chemistry.chemical_compound Adenosine Triphosphate Dogs Nickel Cell Adhesion Extracellular Animals Cell adhesion Molecular Biology Ion transporter Calcium signaling Ion Transport Depolarization Cell Biology Triazoles Calcium Channel Blockers Cell biology chemistry Oligopeptides Intracellular Signal Transduction Research Article |
| Zdroj: | Molecular Biology of the Cell. 7:1025-1041 |
| ISSN: | 1939-4586 1059-1524 |
| Popis: | Peptides containing Arg-Gly-Asp (RGD) immobilized on beads bind to integrins and trigger biphasic, transient increases in intracellular free Ca2+ ([Ca2+]i) in Madin-Darby canine kidney epithelial cells. The [Ca2+]i increase participates in feedback regulation of integrin-mediated adhesion in these cells. We examined influx pathways and inositol 1,4,5-trisphosphate (IP3)-mediated Ca2+ store release as possible sources of the [Ca2+]i rise. The RGD-induced [Ca2+]i response requires external Ca2+ (threshold approximately 150 microM), and its magnitude is proportional to extracellular calcium. RGD-induced transients were attenuated by Ca2+ channel inhibitors (Ni2+ and carboxy-amidotriazole) or by plasma membrane depolarization, indicating that Ca2+ influx contributes to the response. Loading cells with heparin reduced the size of RGD-induced [Ca2+]i transients, indicating that IP3-mediated release of Ca2+ from stores may also contribute to the RGD response. Depletion of Ca2+ stores with thapsigargin activated Ni(2+)-sensitive Ca2+ influx that might also be expected to occur after IP3-mediated depletion of stored Ca2-. However, RGD elicited a Ni(2+)-sensitive Ca2+ influx even after pretreatment with thapsigargin, indicating that Ca2+ influx is controlled by a mechanism independent of IP3-mediated store depletion. We conclude that RGD-induced [Ca2+]i transients in Madin-Darby canine kidney cells result primarily from the combination of two distinct mechanisms: 1) IP3-mediated release of intracellular stores, and 2) activation of a Ca2+ influx pathway regulated independently of IP3 and Ca2+ store release. Because Ni2+ and carboxy-amidotriazole inhibited adhesion, whereas store depletion with thapsigargin had little effect, we suggest that the Ca2+ influx mechanism is most important for feedback regulation of integrin-mediated adhesion by increased [Ca2+]i. |
| Databáze: | OpenAIRE |
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