thapsigargin and Wounds-and-Injuries

Intracellular calcium plays an important part in the regulation of proliferation and differentiation of keratinocytes. Detached from their in vivo environment, cultured psoriatic keratinocytes were investigated by monitoring free intracellular calcium concentration, which was measured using fura-2/AM as a calcium-sensitive probe. The mean increase in intracellular calcium of psoriatic keratinocytes was significantly reduced compared with control keratinocytes when intracellular calcium stores were mobilized from endoplasmic reticulum with thapsigargin. This finding suggests defective capacitative calcium influx of psoriatic cells. Intracellular calcium stores were similar in psoriatic and control keratinocytes, when extracellular calcium was chelated with ethyleneglycol-bis(beta-aminoethyl ether)-N,N,N',N',-tetraacetic acid and intracellular calcium was depleted with thapsigargin. Mechanical wounding of keratinocyte monolayer resulted in a significantly reduced rise in intracellular calcium of psoriatic cells in low (< 0.1 mM) and high (1.8 mM) extracellular calcium suggesting defective intercellular coupling of psoriatic keratinocytes. Blocking of gap-junctions with heptanol in wounded keratinocytes did not affect the intracellular calcium response in psoriatic keratinocytes in contrast to healthy keratinocytes. Adding adenosine triphosphate to culture medium resulted in a more pronounced intracellular calcium increase than thapsigargin in psoriatic keratinocytes, suggesting that inositol triphosphate-mediated, P2-purinergic signaling was enhanced in these cells. Moreover, psoriatic keratinocytes maintained their defective responses up to at least fifth passage suggesting that psoriatic keratinocytes have an inborn error in calcium metabolism, rather than a localized defect in response to altered extracellular calcium gradient observed in vivo.

Topics: Adenosine Triphosphate; Calcium; Carcinogens; Cell Culture Techniques; Chelating Agents; Down-Regulation; Edetic Acid; Female; Humans; Infant, Newborn; Keratinocytes; Male; Middle Aged; Psoriasis; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2; Signal Transduction; Thapsigargin; Wounds and Injuries

The effects of exogenous ATP on Ca2+ signaling and wound healing were investigated in rat gastric microvascular endothelial cells (RGMEC). ATP (10 microM) triggered a significant rise in intracellular Ca2+ concentration ([Ca2+]i) from 46+/-2 nM at baseline to peak values averaging 283+/-31 nM (n = 5 experiments, 132 cells). Return to the basal [Ca2+]i was delayed by slowly declining plateau phase that persisted for 200+/-30 s. Removal of extracellular Ca2+ did not significantly affect the peak rise in [Ca2+]i, but reduced the plateau. ATP (10 microM) also significantly increased the migration of RGMEC in a wounded monolayer. Addition of the non-subtype selective purinergic receptor antagonist, suramin, abrogated the effects of ATP on [Ca2+]i and migration. We conclude that local elevation of ATP acting through purinergic receptors induce Ca2+ signals in RGMEC and may contribute to endothelial cell migration.

Topics: Adenosine Triphosphate; Animals; Calcium; Calcium Signaling; Cell Movement; Cells, Cultured; Endothelium, Vascular; Enzyme Inhibitors; Intracellular Membranes; Microcirculation; Purinergic Antagonists; Rats; Stomach; Suramin; Thapsigargin; Wound Healing; Wounds and Injuries