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Curr Biol. 2009 May 26;19(10):853-8. doi: 10.1016/j.cub.2009.03.063. Epub 2009 Apr 16.

Decoding of cytoplasmic Ca(2+) oscillations through the spatial signature drives gene expression.

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1
Department of Physiology, Anatomy and Genetics, University of Oxford, Parks Road, Oxford OX1 3PT, UK.

Abstract

Cytoplasmic Ca(2+) oscillations are a universal signaling mode that activates numerous cellular responses [1, 2]. Oscillations are considered the physiological mechanism of Ca(2+) signaling because they occur at low levels of stimulus intensity [3]. Ca(2+) oscillations are proposed to convey information in their amplitude and frequency, leading to activation of specific downstream targets [4-6]. Here, we report that the spatial Ca(2+) gradient within the oscillation is key. Ca(2+) oscillations in mast cells evoked over a range of agonist concentrations in the presence of external Ca(2+) were indistinguishable from those in the absence of Ca(2+) when plasmalemmal Ca(2+) extrusion was suppressed. Nevertheless, only oscillations with accompanying Ca(2+) entry through store-operated CRAC channels triggered gene expression. Increased cytoplasmic Ca(2+) buffering prevented oscillations but not gene activation. Local Ca(2+) influx and not global Ca(2+) oscillations therefore drives gene expression at physiological levels of stimulation. Rather than serving to maintain Ca(2+) oscillations by replenishing stores, we suggest that the role of oscillations might be to activate CRAC channels, thereby ensuring the generation of spatially restricted physiological Ca(2+) signals driving gene activation. Furthermore, we show that the spatial profile of a Ca(2+) oscillation provides a novel mechanism whereby a pleiotropic messenger specifically activates gene expression.

PMID:
19375314
DOI:
10.1016/j.cub.2009.03.063
[Indexed for MEDLINE]
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