Inhibitors of actin polymerisation stimulate arachidonic acid release and 5-lipoxygenase activation by upregulation of Ca2+ mobilisation in polymorphonuclear leukocytes involving Src family kinases.
Here, we show that actin polymerisation inhibitors such as latrunculin B (LB), and to a minor extent also cytochalasin D (Cyt D), enhance the release of arachidonic acid (AA) as well as nuclear translocation of 5-lipoxygenase (5-LO) and 5-LO product synthesis in human polymorphonuclear leukocytes (PMNL), challenged with thapsigargin (TG) or N-formyl-methionyl-leucyl-phenylalanine. The concentration-dependent effects of LB (EC50 approximately 200 nM) declined with prolonged preincubation (>3 min) prior TG and were barely detectable when PMNL were stimulated with Ca2+-ionophores. Investigation of the stimulatory mechanisms revealed that LB (or Cyt D) elicits Ca2+ mobilisation and potentiates stimulus-induced elevation of intracellular Ca2+, regardless of the nature of the stimulus. LB caused rapid but only moderate activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK)2. The selective Src family kinase inhibitors PP2 and SU6656 blocked LB- or Cyt D-mediated Ca2+ mobilisation and suppressed the upregulatory effects on AA release and 5-LO product synthesis, without affecting AA metabolism evoked by ionophore alone. We conclude that in PMNL, inhibitors of actin polymerisation cause enhancement of intracellular Ca2+ levels through Src family kinase signaling, thereby facilitating stimulus-induced release of AA and 5-LO product formation.
Fischer
Lutz
L
Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie Strasse 9, D-60439 Frankfurt, Germany.
Poeckel
Daniel
D
Buerkert
Eva
E
Steinhilber
Dieter
D
Werz
Oliver
O
D000199:Actins / Q000378:metabolism*; D000328:Adult; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000378:metabolism / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D015638:Cytochalasin D / Q000378:metabolism / Q000494:pharmacology*; D004789:Enzyme Activation; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011108:Polymers; D019284:Thapsigargin / Q000494:pharmacology; D013844:Thiazoles / Q000378:metabolism / Q000494:pharmacology*; D053778:Thiazolidines; D015854:Up-Regulation; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D019384:Nucleic Acid Synthesis Inhibitors; D011108:Polymers; D013844:Thiazoles; D053778:Thiazolidines; D015638:Cytochalasin D; D016718:Arachidonic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019284:Thapsigargin; D001094:Arachidonate 5-Lipoxygenase; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases; C037068:latrunculin B; D002118:Calcium