Cyclosporin H is a potent and selective formyl peptide receptor antagonist. Comparison with N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L- leucyl-L-phenylalanine and cyclosporins A, B, C, D, and E.
The cyclic undecapeptide, cyclosporin (Cs) H, is a potent inhibitor of FMLP-induced superoxide anion (O2-) formation in human neutrophils. We studied the effects of CsH in comparison with those of N-t-butoxycarbonyl-L-phenylalanyl-L-leucyl-L-phenylalanyl-L-leucyl-L- phenylalanine (BocPLPLP), a well known formyl peptide receptor antagonist, and of other Cs on activation of N6,2'-O-dibutyryl adenosine 3:5'-monophosphate-differentiated HL-60 cells and human erythroleukemia cells (HEL cells). CsH inhibited FMLP binding in HL-60 membranes with a Ki (inhibition constant) of 0.10 microM. CsH inhibited activation by FMLP of high affinity GTPase (the enzymatic activity of alpha-subunits of heterotrimeric regulatory guanine nucleotide-binding proteins) in HL-60 membranes with a Ki of 0.79 microM. CsH inhibited the stimulatory effects of FMLP on cytosolic Ca2+ concentration ([Ca2+]i), O2- formation, and beta-glucuronidase release with Ki values of 0.08, 0.24, and 0.45 microM, respectively. BocPLPLP was 14-fold less potent than CsH in inhibiting FMLP binding and 4- to 6-fold less potent than CsH in inhibiting FMLP-induced GTP hydrolysis, rises in [Ca2+]i, O2- formation, and beta-glucuronidase release. CsA reduced FMLP-induced O2- formation by 20%, but CsB, CsC, CsD, and CsE did not. CsA, CsB, CsC, CsD, and CsE did not affect FMLP-induced rises in [Ca2+]i. BocPLPLP inhibited leukotriene B4-induced rises in [Ca2+]i with a Ki of 0.33 microM, whereas CsH showed no inhibitory effect. CsH and BocPLPLP did not inhibit the rises in [Ca2+]i induced by several other stimuli in HL-60 cells and HEL cells. Our results show that 1) CsH is a more potent formyl peptide receptor antagonist than BocPLPLP; 2) unlike BocPLPLP, CsH is selective; and 3) N-methyl-D-valine which is present at position 11 of the amino acid sequence of CsH but not of other Cs is crucial for FMLP antagonism.
Institut für Pharmakologie, Freie Universität Berlin, Federal Republic of Germany.
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D000595:Amino Acid Sequence; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D016572:Cyclosporine; D003524:Cyclosporins / Q000494:pharmacology*; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors*; D013481:Superoxides / Q000378:metabolism; D014407:Tumor Cells, Cultured
D003524:Cyclosporins; D009842:Oligopeptides; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D003994:Bucladesine; C033373:butyloxycarbonyl-phenylalanyl-leucyl-phenylalanyl-leucyl-phenylalanine; D016572:Cyclosporine; D005966:Glucuronidase; C050025:cyclosporin H