A Hyperosmotic Stimulus Elevates Intracellular Calcium and Inhibits Proliferation of a Human Keratinocyte Cell Line
Journal of Investigative Dermatology(2000)
摘要
Occlusion has previously been used to treat psoriatic plaques and was shown to improve the condition. We investigated the consequences of applying a mechanical stress, in vitro, on the HaCaT keratinocyte cell line. A mechanical load applied to cells can be mimicked by a hyperosmotic stimulus. Exposure of HaCaT keratinocytes to different hyperosmotic solutions (final osmolarity in the range 350-600 mOsm, produced by sucrose addition) resulted in an inhibition of cell proliferation after 96 h of treatment. As keratinocyte maturation is regulated by calcium levels, we measured hyperosmotic-stimulus-induced changes of intracellular calcium ([Ca2+](i)) by single-cell image analysis employing FURA-2/AM. The hyperosmotic stimulus produced a rapid transient 2.6-fold elevation of [Ca2+](i) followed by a gradual decay to the basal level. The transients originated from extracellular as well as from intracellular calcium pools and did not respond to voltage-sensitive calcium channel blockers. The hyperosmotic stimulus was shown to increase the cellular expression of involucrin, a differentiation marker, following 72 h of incubation, as measured by flow cytometry. Treatment of cells with the [Ca2+](i) chelator BAPTA/AM almost completely blocked the [Ca2+](i) elevation, but did not alter cellular growth or the induction of differentiation observed after hyperosmotic stimulus. It is suggested that treatment of keratinocytes with hyperosmotic stimulus can induce short-time effects (calcium transients) as well as long-term cellular maturation.
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关键词
differentiation,HaCaT,osmotic,second messenger
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