Overview
- Bae, Y.S. et al. (2004) J. Immunol. 173, 607.
Alomone Labs WRW4 blocks Ca2+ transients in differentiated HL-60 cells, generated by MMK1 application.Cells were loaded with Fluo-3 AM. Changes in intracellular Ca2+ were detected via changes in Fluo-3 emission following application (indicated by arrow) of 1µM MMK1 (#GPM-120). 30min pre-incubation with various concentrations of WRW4 (#GPW-110) resulted in a dose-dependent inhibition of FPR2 activation. A. Normalized fluorescence levels before and after application (indicated by an arrow) of control saline solution (black) or of 1µM MMK1 in cells pre-incubated with 0 µM (red), 0.25 µM (green), 1 µM (purple) and 5 µM (blue) WRW4. B. Inhibition of FPR2 activation plotted against WRW4 concentrations.
Chemotactic factors from both Gram-positive and Gram-negative bacteria are short peptides with N-formyl methionine at the N-terminus (extensively reviewed in reference 1). These peptides are released from bacteria during infection and activate formyl peptide receptors (FPR), members of the G-protein coupled receptor (GPCR) superfamily. In humans, the FPR family consists mainly of three receptors, FPR1, FPR2/ALX (formerly FPRL1), and FPR3 (formerly FPRL2) which all couple to the Gi subtype of G-proteins and ultimately lead to the activation of phospholipase C and intracellular Ca2+ increase1,2.
WRW4 is a selective and potent antagonist of the Formyl peptide receptors (FPR2 and FPR3)3,4, which was identified by screening hexapeptide libraries that inhibit the binding of the FPR2 agonist WKYMVm to its specific receptor, in RBL-2H3 cells3. In human umbilical vein endothelial cells, WRW4 (10 mM), inhibited CCL2 production, which was stimulated by serum amyloid A5.
FPR2 is expressed in the promyelocytic leukemia cell line HL-60 as well as in the chronic myelogenous leukemia cell line K5626. In human neutrophils, 10 µM WRW4 blocked the specific FPR2 agonist (MMK1) induced Ca2+ influx. In addition, at the same concentration WRW4 blocked Ca2+ influxes, generated by stimulation with the Alzheimer’s diseases Amiloide β42 peptide, by lipoxin A4 and by fMLF3.
