Antimicrobial and immunostimulatory peptide, KLK, induces an increase in cytosolic Ca²(+) concentration by mobilizing Ca²(+) from intracellular stores.
The cationic antimicrobial immunomodulatory peptide, KLK (KLKL₅KLK), exerts profound membrane interacting properties, impacting on ultrastructure and fluidity. KLK-membrane interactions that lead to these alterations require the ability of the peptide to move into an α-helical conformation. We show that KLK induces an increase of the intracellular Ca²(+) concentration in human T24 cells. The effect of KLK is buffer-sensitive, as it is detected when HBSS buffer is used, but not with PBS. This, together with the lack of effect of the middle leucine-to-proline-substituted peptide derivative [KPK (KLKLLPLLKLK)], indicates that it is the conformational propensity rather than the net positive charge that contributes to the effect of KLK on intracellular Ca²(+) level of T24 cells. We show that, although KLK slightly stimulates Ca²(+) influx into the cell, the bulk increase of Ca²(+) levels is due to KLK-induced depletion of intracellular Ca²(+) stores. Finally, we demonstrate a KLK-induced switch of PS (phosphatidylserine) from the inner to the outer plasma membrane leaflet that contributes to the onset of early apoptotic changes in these cells.
Weghuber
Julian
J
Biophysics Institute, Johannes Kepler University Linz, Austria. julian.weghuber@jku.at
Lipp
Anna M
AM
Stadlbauer
Jacqueline
J
Aichinger
Michael C
MC
Ruprecht
Verena
V
Sonnleitner
Alois
A
Schütz
Gerhard J
GJ
Henics
Tamás
T
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D009842:Oligopeptides / Q000494:pharmacology*; D010718:Phosphatidylserines / Q000378:metabolism
D000276:Adjuvants, Immunologic; D023181:Antimicrobial Cationic Peptides; D009842:Oligopeptides; D010718:Phosphatidylserines; C531381:lysyl-leucyl-lysyl-leucyl-leucyl-leucyl-leucyl-leucyl-lysyl-leucyl-lysine; D002118:Calcium