Effect of protein kinase C on transmembrane calcium fluxes in HaCaT keratinocytes.
Capacitive calcium influx is associated with the release of calcium from internal stores and participates in intracellular calcium homeostasis. In keratinocytes, its activation is linked to the stimulation of the phospho-inositide (PI) pathway and seems to be altered in psoriasis. An overnight treatment of isolated HaCaT keratinocytes with phorbol 12-myristate 13-acetate (PMA) selectively downregulated the classical, calcium-dependent protein kinase C (PKC) isoenzyme PKC alpha in preconfluent cells. This was parallelled by an increased capacitative calcium influx with no effects on the PI pathway. These observations were strengthened in measurements using cyclopiazonic acid which revealed a 47% increase in PMA pretreated as compared with control cells in the calcium influx rate through store-operated calcium channels (SOC-s) following the emptying of the intracellular calcium stores. In confluent as compared with preconfluent cultures PKC epsilon was markedly increased, while other isoenzymes were not affected. In parallel, the kinetics of capacitative calcium influx were altered, showing clear inactivation. PMA pretreatment in these cells had little effect on PKC alpha but downregulated both PKC beta and PKC epsilon, and did not increase the influx through SOC-s. These observations support the differential regulation of SOC-s by PKC and suggest the involvement of several PKC isoenzymes in human keratinocytes.
Gönczi
Mónika
M
Department of Physiology, University of Debrecen, Medical & Health Science Center and Cell Physiology Research, Medical School, Debrecen, Hungary.
Papp
Helga
H
Bíró
Tamás
T
Kovács
László
L
Csernoch
László
L
D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D015603:Keratinocytes / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007211:Indoles; D007473:Ion Channels; D007527:Isoenzymes; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C000543:cyclopiazonic acid