title: Effects of the semisynthetic bis-indole derivative KAR-2 on store-operated calcium entry in human neutrophils.
abstract: We studied the effect of KAR-2 on cytosolic Ca(2+) level in human neutrophils by using a fluorescent dye (Fura-2) trapped in the cells. KAR-2 is a semisynthetic bis-indole derivative that shares vinblastine anti-microtubular properties, but does not share the vinblastine antagonistic effect on calmodulin. Therefore KAR-2 offers a convenient mean of studying the effect of microtubule destabilization, without concomitant calmodulin alterations. We found that KAR-2 induces Ca(2+) release from intracellular stores, whereby the stores are depleted. In addition KAR-2 reduces store-operated entry of extracellular Ca(2+) induced by agonists such as thapsigargin or ATP. On the other hand, in Ca(2+) refilled cells, KAR-2 promotes limited entry of extracellular Ca(2+) in the absence of agonist, but still interferes prominently with Ca(2+) entry triggered by ATP and with Ca(2+) uptake by intracellular stores. We suggest that Ca(2+) traffic through the plasma membrane is operated by two diverse pathways: the prominent pathway is interfered with by microtubule destabilization, while an alternate and minor pathway is actually favored (or uncovered) following microtubule destabilization.
authors.affiliation: Department of Biochemical Sciences, University of Rome La Sapienza, Italy. costantino.salerno@uniroma1.it
authors.forename: Costantino
authors.initials: C
authors.lastname: Salerno
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Capuozzo
mesh_terms: D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum; D006801:Humans; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D014747:Vinblastine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D014747:Vinblastine; C107832:deacetoxyvinzolidine; D002118:Calcium
keywords: Calcium channels; Microtubules; Neutrophils; Store-operated calcium entry; Vinca alkaloids