Mechanism of calcium oscillations in migrating human astrocytoma cells.
BIOCHIMICA ET BIOPHYSICA ACTA 2000;
1498:273-80. [PMID:
11108969 DOI:
10.1016/s0167-4889(00)00102-6]
[Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Numerous studies show that intracellular calcium controls the migration rate of different mobile cell types. We studied migrating astrocytoma cells from two human cell lines, U-87MG and A172, in order to clarify the mechanisms by which calcium potentially influences cell migration. Using the wound-healing model to assay migration, we showed that four distinct components of migration could be distinguished: (i) a Ca(2+)/serum-dependent process; (ii) a Ca(2+)-dependent/serum-independent process; (iii) a Ca(2+)/serum-independent process; (iv) a Ca(2+)-independent/serum-dependent process. In U-87MG cells which lack a Ca(2+)-dependent/serum-independent component, we found that intracellular Ca(2+) oscillations are involved in Ca(2+)-dependent migration. Removing extracellular Ca(2+) greatly decreased the frequency of migration-associated Ca(2+) oscillations. Furthermore, non-selective inhibition of Ca(2+) channels by heavy metals such as Cd(2+) or La(3+) almost completely abolished changes in intracellular Ca(2+) observed during migration, indicating an essential role for Ca(2+) channels in the generation of these Ca(2+) oscillations. However, specific blockers of voltage-gated Ca(2+) channels, including nitrendipine, omega-conotoxin GVIA, omega-conotoxin MVIIC or low concentrations of Ni(2+) were without effect on Ca(2+) oscillations. We examined the role of internal Ca(2+) stores, showing that thapsigargin-sensitive Ca(2+) stores and InsP(3) receptors are involved in Ca(2+) oscillations, unlike ryanodine-sensitive Ca(2+) stores. Detailed analysis of the spatio-temporal aspect of the Ca(2+) oscillations revealed the existence of Ca(2+) waves initiated at the leading cell edge which propagate throughout the cell. Previously, we have shown that the frequency of Ca(2+) oscillations was reduced in the presence of inhibitory antibodies directed against beta3 integrin subunits. A simple model of a Ca(2+) oscillator is proposed, which may explain how the generation of Ca(2+) oscillations is linked to cell migration.
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