Direct modification of the proinflammatory cytokine macrophage migration inhibitory factor by dietary isothiocyanates.
Isothiocyanates are a class of phytochemicals with widely reported anti-cancer and anti-inflammatory activity. However, knowledge of their activity at a molecular level is limited. The objective of this study was to identify biological targets of phenethyl isothiocyanate (PEITC) using an affinity purification approach. An analogue of PEITC was synthesized to enable conjugation to a solid-phase resin. The pleiotropic cytokine macrophage migration inhibitory factor (MIF) was the major protein captured from cell lysates. Site-directed mutagenesis and mass spectrometry showed that PEITC covalently modified the N-terminal proline residue of MIF. This resulted in complete loss of catalytic tautomerase activity and disruption of protein conformation, as determined by impaired recognition by a monoclonal antibody directed to the region that receptors and interacting proteins bind to MIF. The conformational change was supported by in silico modeling. Monoclonal antibody binding to plasma MIF was disrupted in humans consuming watercress, a major dietary source of PEITC. The isothiocyanates have significant potential for development as MIF inhibitors, and this activity may contribute to the biological properties of these phytochemicals.
Brown
Kristin K
KK
Free Radical Research Group, Department of Pathology, University of Otago, Christchurch 8140, New Zealand.
Blaikie
Frances H
FH
Smith
Robin A J
RA
Tyndall
Joel D A
JD
Lue
Hongqi
H
Bernhagen
Jürgen
J
Winterbourn
Christine C
CC
Hampton
Mark B
MB
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007249:Inflammation; D017879:Isothiocyanates / Q000737:chemistry*; D019169:Jurkat Cells; D008263:Macrophage Migration-Inhibitory Factors / Q000378:metabolism*; D008954:Models, Biological; D008956:Models, Chemical; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation
D000911:Antibodies, Monoclonal; D016207:Cytokines; D017879:Isothiocyanates; D008263:Macrophage Migration-Inhibitory Factors