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Ca²? and calpain control membrane expansion during the rapid cell spreading of neutrophils.

ABSTRACT: Following adherence of neutrophils to the endothelium, neutrophils undergo a major morphological change that is a necessary prelude to their extravasation. We show here that this shape change is triggered by an elevation of cytosolic inositol (1,4,5)-trisphosphate (IP3), to provoke physiological Ca(2+) influx through a store-operated mechanism. This transition from a spherical to 'flattened' neutrophil morphology is rapid (?100 seconds) and is accompanied by an apparent rapid expansion of the area of the plasma membrane. However, no new membrane is added into the plasma membrane. Pharmacological inhibition of calpain-activation, which is triggered by Ca(2+) influx during neutrophil spreading, prevents normal cell flattening. In calpain-suppressed cells, an aberrant form of cell spreading can occur where an uncoordinated and localised expansion of the plasma membrane is evident. These data show that rapid neutrophil spreading is triggered by Ca(2+) influx, which causes activation of calpain and release of furled plasma membrane to allow its apparent 'expansion'.

SUBMITTER: Dewitt S

PROVIDER: S-EPMC3795336 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Ca²⁺ and calpain control membrane expansion during the rapid cell spreading of neutrophils.

Dewitt Sharon S Francis Robert J RJ Hallett Maurice B MB

Journal of cell science 20130813 Pt 20

Following adherence of neutrophils to the endothelium, neutrophils undergo a major morphological change that is a necessary prelude to their extravasation. We show here that this shape change is triggered by an elevation of cytosolic inositol (1,4,5)-trisphosphate (IP3), to provoke physiological Ca(2+) influx through a store-operated mechanism. This transition from a spherical to 'flattened' neutrophil morphology is rapid (∼100 seconds) and is accompanied by an apparent rapid expansion of the ar ...[more]

PMID: 23943875

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Project description:Human neutrophils are mediators of innate immunity and undergo dramatic shape changes at all stages of their functional life cycle. In this work, we quantified the forces associated with a neutrophil's morphological transition from a nonadherent, quiescent sphere to its adherent and spread state. We did this by tracking, with high spatial and temporal resolution, the cell's mechanical behavior during spreading on microfabricated post-array detectors printed with the extracellular matrix protein fibronectin. Two dominant mechanical regimes were observed: transient protrusion and steady-state contraction. During spreading, a wave of protrusive force (75 ± 8 pN/post) propagates radially outward from the cell center at a speed of 206 ± 28 nm/s. Once completed, the cells enter a sustained contractile state. Although post engagement during contraction was continuously varying, posts within the core of the contact zone were less contractile (-20 ± 10 pN/post) than those residing at the geometric perimeter (-106 ± 10 pN/post). The magnitude of the protrusive force was found to be unchanged in response to cytoskeletal inhibitors of lamellipodium formation and myosin II-mediated contractility. However, cytochalasin B, known to reduce cortical tension in neutrophils, slowed spreading velocity (61 ± 37 nm/s) without significantly reducing protrusive force. Relaxation of the actin cortical shell was a prerequisite for spreading on post arrays as demonstrated by stiffening in response to jasplakinolide and the abrogation of spreading. ROCK and myosin II inhibition reduced long-term contractility. Function blocking antibody studies revealed haptokinetic spreading was induced by β2 integrin ligation. Neutrophils were found to moderately invaginate the post arrays to a depth of ∼1 μm as measured from spinning disk confocal microscopy. Our work suggests a competition of adhesion energy, cortical tension, and the relaxation of cortical tension is at play at the onset of neutrophil spreading.

Dataset Information

Ca²? and calpain control membrane expansion during the rapid cell spreading of neutrophils.

Publications

Ca²⁺ and calpain control membrane expansion during the rapid cell spreading of neutrophils.

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