Effects of buffering intracellular free calcium on neutrophil migration through three-dimensional matrices

Abstract

Repeated transient increases in intracellular free calcium levels ([Ca2-]i) are required for polymorphonuclear neutrophil migration on two-dimensional surfaces coated with fibronectin or vitronectin. Cells in which [Ca2+]i is buffered with quin2 become stuck on these substrates. Neutrophils migrating through the extracellular matrix in vivo encounter these and other substrates in a three-dimensional architecture that may alter the spatial distribution of adhesion receptors in contact with the matrix. In this study, we used fluorescence confocal microscopy to obtain moving three-dimensional images of neutrophils migrating through a biological tissue (human amnion) in the presence and absence of [Ca2+]i-buffering with quin2. In the absence of buffering, [Ca2+]i transients similar to those seen in cells migrating in two-dimensions were observed. [Ca2+]i-buffered neutrophils were able to migrate into the matrix, but they became attached firmly to the substrate at the rear of the cell, resulting in a drastically elongated morphology. Immunofluorescence revealed that neutrophils adhered to regions of the matrix that contained fibronectin. RGD-containing peptides and antibodies that block integrin adhesion receptors for fibronectin and vitronectin were able to rescue the migration of quin2-treated cells through three-dimensional gels containing fibronectin and vitronectin. These data show that neutrophils migrating through physiologically relevant, three-dimensional matrices undergo repetitive increases in [Ca2+]i that are required for integrin-mediated detachment from the matrix.

Cells move when ions and water flow

“…There is a strict necessity for a tight regulation of the intracellular Ca 2+ concentration ([Ca 2+ ] i ). Many migrating cells exhibit oscillations of [Ca 2+ ] i [21,73]. In addition, there are spatial differences of [Ca 2+ ] i in migrating cells.…”

The regulation of integrin function by divalent cations

“…In addition to extracellular divalent cations, integrin can also be activated by intracellular proteins or stimuli, such as talin, through a process termed inside-out signaling. [8][9][10][11][12][13] Moreover, ligand occupancy can induce integrin conformational change and transduce extracellular signals into cytoplasm through outside-in signaling. 9,14 Integrin-mediated adhesion and signaling events are important in normal physiological responses including immune response, tissue morphogenesis, wound healing, hemostasis, cell survival and cell differentiation.…”

Requirement of functional ryanodine receptor type 3 for astrocyte migration

“…Calcium ions are known to play an integrative role in cell migration. Interference with the physiological level of intracellular calcium affects cell migration (6)(7)(8). Intracellular calcium ion concentration is a key second messenger in lamellipodia extension (9), filopodia induction (10), nerve growth cone turning and extension (11), and actin reorganization, which is prerequisite for a functional actin-myosin motor unit capable of generating contractile force.…”