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Title

Multiple elevations of cytosolic-free Ca2+ in human neutrophils: initiation by adherence receptors of the integrin family

Authors
Jaconi, Marisa
Theler, J. M.
Wright, S. D.
Published in The Journal of Cell Biology. 1991, vol. 112, no. 6, p. 1249-1257
Abstract Multiple spontaneous transient elevations of cytosolic-free calcium ([Ca2+]i) are observed in single human neutrophils during adherence. The interrelation between adherence and spontaneous [Ca2+]i transients was analyzed by simultaneous monitoring of [Ca2+]i and cell morphology. Fluorescent images of fura 2-loaded neutrophils attached to albumin-coated glass were recorded with a high sensitivity CCD camera while [Ca2+]i was assessed with a dual excitation microfluorimetry. The majority of the initially round cells studied showed changes in shape which started either before or at the same time as the onset of the [Ca2+]i transients. These data suggested that a rise in [Ca2+]i is not a prerequisite for shape change. This conclusion was confirmed by observation of movement and spreading in cells whose [Ca2+]i transients were abolished by chelation of extracellular Ca2+. Instead, our data suggest that spreading or adhesion itself initiates the [Ca2+]i activity. In keeping with this hypothesis, cytochalasin B, which prevents both cell movement and adhesion, completely inhibited generation of [Ca2+]i transients. To determine if the movement alone or adhesion alone is responsible for [Ca2+]i activity, we treated cells with antibodies against the beta chain (CD18, beta 2) or the alpha subunit (CD11b, alpha m) of the dominant leukocyte integrin (CR3). Antibody-treated cells showed normal extension of pseudopods but impaired ability to adhere. Inhibition of adhesion in this way inhibited [Ca2+]i activity. Taken together these results suggest that following sequence of events after contact of neutrophils with surfaces: (a) cell movement and shape change lead to enhanced contact of integrins with the surface; and (b) integrins-mediated adhesion generates multiple [Ca2+]i transients. The [Ca2+]i transients may then control exocytic events associated with movement and may provide a link between adherence and activation or priming of neutrophils to other stimuli.
Keywords Antibodies, Monoclonal/diagnostic useCalcium/ bloodCell Adhesion/drug effectsCell Membrane/physiologyCytochalasin B/pharmacologyCytosol/metabolismEgtazic Acid/pharmacologyFura-2HumansIntegrins/drug effects/ physiologyKineticsMicroscopy, FluorescenceNeutrophils/cytology/drug effects/ physiologySoftware
Identifiers
PMID: 1900302
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Other version: http://jcb.rupress.org/content/112/6/1249.full.pdf
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JACONI, Marisa et al. Multiple elevations of cytosolic-free Ca2+ in human neutrophils: initiation by adherence receptors of the integrin family. In: The Journal of Cell Biology, 1991, vol. 112, n° 6, p. 1249-1257. doi: 10.1083/jcb.112.6.1249 https://archive-ouverte.unige.ch/unige:11357

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Deposited on : 2010-08-27

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