Fundamental Ca super(2+) Signaling Mechanisms in Mouse Dendritic Cells: CRAC Is the Major Ca super(2+) Entry Pathway

• Published in: The Journal of immunology (1950) Vol. 166; no. 10; pp. 6126 - 6133
• Main Authors: Hsu, S, O'Connell, P J, Klyachko, V A, Badminton, M N, Thomson, A W, Jackson, M B, Clapham, DE, Ahern, G P
• Format: Journal Article
• Language: English
• Published: 15.05.2001
• ISSN: 0022-1767

Although Ca super(2+)-signaling processes are thought to underlie many dendritic cell (DC) functions, the Ca super(2+) entry pathways are unknown. Therefore, we investigated Ca super(2+)-signaling in mouse myeloid DC using Ca super(2+) imaging and electrophysiological techniques. Neither Ca super(2+) currents nor changes in intracellular Ca super(2+) were detected following membrane depolarization, ruling out the presence of functional voltage-dependent Ca super(2+) channels. ATP, a purinergic receptor ligand, and 1 4 dihydropyridines, previously suggested to activate a plasma membrane Ca super(2+) channel in human myeloid DC, both elicited Ca super(2+) rises in murine DC. However, in this study these responses were found to be due to mobilization from intracellular stores rather than by Ca super(2+) entry. In contrast, Ca super(2+) influx was activated by depletion of intracellular Ca super(2+) stores with thapsigargin, or inositol trisphosphate. This Ca super(2+) influx was enhanced by membrane hyperpolarization, inhibited by SKF 96365, and exhibited a cation permeability similar to the Ca super(2+) release-activated Ca super(2+) channel (CRAC) found in T lymphocytes. Furthermore, ATP, a putative DC chemotactic and maturation factor, induced a delayed Ca super(2+) entry with a voltage dependence similar to CRAC. Moreover, the level of phenotypic DC maturation was correlated with the extracellular Ca super(2+) concentration and enhanced by thapsigargin treatment. These results suggest that CRAC is a major pathway for Ca super(2+) entry in mouse myeloid DC and support the proposal that CRAC participates in DC maturation and migration.