Dominant effect of gap junction communication in wound‐induced calcium‐wave, NFAT activation and wound closure in keratinocytes

Abstract

Wounding induces a calcium wave and disrupts the calcium gradient across the epidermis but mechanisms mediating calcium and downstream signalling, and longer-term wound healing responses are incompletely understood. As expected, live-cell confocal imaging of Fluo-4-loaded normal human keratinocytes showed an immediate increase in [Ca 2+ ] i at the wound edge that spread as a calcium wave (8.3 µm/s) away from the wound edge with gradually diminishing rate of rise and amplitude. The amplitude and area under the curve of [Ca 2+ ] i flux was increased in high (1.2 mM) [Ca 2+ ] o media. 18α-glycyrrhetinic acid (18αGA), a gap-junction inhibitor or hexokinase, an ATP scavenger, blocked the wound-induced calcium wave, dependent in part on [Ca 2+ ] o . Wounding in a high [Ca 2+ ] o increased nuclear factor of activated T-cells (NFAT) but not NFkB activation, assessed by dual-luciferase receptor assays compared to unwounded cells. Treatment with 18αGA or the storeoperated channel blocker GSK-7975A inhibited wound-induced NFAT activation, whereas treatment with hexokinase did not. Real-time cell migration analysis, measuring wound closure rates over 24 h, revealed that 18αGA essentially blocked wound closure whereas hexokinase and GSK-7975A showed relatively minimal effects. Together these data indicate that while both gap-junction communication and ATP release from damaged cells are important in regulating the wound-induced calcium wave, long-term transcriptional and functional responses are dominantly regulated by gap-junction communication.

Influence of gap junctions upon Ca²⁺ propagation from stimulated keratinocytes to DRG neurons

“…Gap junctions are also crucial for skin function as a barrier to protect against inflammation [ 10 ]. They are also involved in the Ca 2+ wave caused by the wound [ 11 ]. Mechanical stimulation evokes Ca 2+ waves in keratinocytes via gap junctions [ 12 ].…”

Dendritic cells overcome Cre/Lox induced gene deficiency by siphoning cytosolic material from surrounding cells

“…While we did not directly test the functionality of transferred protein in this study, one out of many viable explanations for LC’s possession of Cx43 is to prevent the disruption of wound healing, which is dependent on the direct transfer of Ca 2+ , IP 3 , and ATP through gap junctions and the ensuing calcium waves. 54 , 55 These waves are projected to travel through LCs as well as KCs, 56 supporting that LCs might acquire functional protein to help them adapt to their environment. Further studies investigating the fate and function of transferred material will help elucidate the roles of ICM in microenvironmental adaptation.…”

Role of vitamin D and calcium signaling in epidermal wound healing

“…Vitamin D can impact a number of processes involved with wound healing including the inflammatory and immune response [7] and the proliferation and differentiation of both fibroblasts and keratinocytes [8][9][10]. Moreover, vitamin D has a major influence on calcium metabolism (and vice versa), and calcium signaling plays a critical role in normal wound healing [11,12]. We [13] have used a mouse model lacking both the vitamin D receptor (Vdr) and the calcium sensing receptor (Casr) to show this delay in wound healing (Fig.…”