The Role of Ca²⁺ Transport Across the Plasma Membrane for Cell Migration

Abstract

Cell migration plays a central role in many physiological and pathophysiological processes. On a cellular level it is based on a highly coordinated restructuring of the cytoskeleton, a continuous cycle of adhesion and de-adhesion as well as on the activity of ion channels and transporters. The cytoplasmic Ca²⁺ ([Ca²⁺]_i) concentration is an important coordinator of these intracellular processes. Thus, [Ca²⁺]_i must be tightly controlled in migrating cells. This is among other things achieved by the activity of Ca²⁺ permeable channels, the plasma membrane Ca²⁺-ATPase (PMCA) and the Na⁺/Ca²⁺ exchanger (NCX) in the plasma membrane. Here, we wanted to determine the functional role of these transport proteins in cell migration. We therefore quantified the acute effect of inhibitors of these transport proteins (Gd³⁺, vanadate, KB-R7943) on migration, [Ca²⁺]_i, and intracellular pH (pH_i) of MDCK-F cells. Migration was monitored with computer-assisted time-lapse video microscopy. [Ca²⁺]_i and pH_i were measured with the fluorescent indicators fura-2 and BCECF. NCX expression in MDCK-F cells was verified with ion substitution experiments, and expression of PMCA was tested with RT-PCR. All blockers lead to a rapid impairment of cell migration. However, the most prominent effect is elicited by NCX-inhibition with KB-R7943. NCX-blockade leads to an almost complete inhibition of migration which is accompanied by a dose-dependent increase of [Ca²⁺]_i and an intracellular alkalinisation. We show that inhibition of NCX and PMCA strongly affects lamellipodial dynamics of migrating MDCK-F cells. Taken together, our results show that PMCA and in particular NCX are of critical importance for cell migration.

KIBRA Modulates Directional Migration of Podocytes

“…To this end, the outlines of individual cells were marked semiautomatically at each time step throughout the entire image stacks with Amira software (Mercury Computer Systems, Duesseldorf, Germany) as described previously. 46,47 These segmentation data were used for further processing. Migration was quantified as the movement of the cell center.…”

TRPC1 channels regulate directionality of migrating cells

“…One day prior to the experiment, cells were seeded on fibronectin-coated (1μg/cm ] i was calculated as described before [10]. Briefly, Ca 2+ measurements were calibrated at the end of each experiment.…”

“…The precise temporal and spatial regulation of [Ca 2+ ] i is required for cellular motility. As a consequence, Ca 2+ -permeable channels, the plasma membrane Ca 2+ -adenosine triphosphatase, and especially the Na + -Ca 2+ exchanger are decisive for cell migration [10]. Moreover, [Ca 2+ ] i gradients have been shown to be important in determining cellular polarity and thereby directionality [16,20,36].…”

Na+/Ca2+exchangers regulate the migration and proliferation of human gastric myofibroblasts

“…It is believed that Ca 2ϩ entry, mediated by store depletion, through the reverse mode of NCX increases [Ca 2ϩ ] i , thus stimulating motility in rat tendon fibroblasts (36). In Madin-Darby canine kidney cells, the plasma membrane Ca 2ϩ -ATPase and particularly the NCX are neces-G561 Na ϩ /Ca 2ϩ EXCHANGERS IN HUMAN GASTRIC MYOFIBROBLASTS sary for cell migration, and the lack of NCX function almost fully abrogates migration (9).…”