H. Jung et al., Regulation of macrophage migration inhibitory factor and thiol-specific antioxidant protein PAG by direct interaction, J BIOL CHEM, 276(18), 2001, pp. 15504-15510
Macrophage migration inhibitory factor (MIF) is an important mediator that
plays a central role in the control of the host immune and inflammatory res
ponse. To investigate the molecular mechanism of MIF action, we have used t
he yeast two-hybrid system and identified PAG, a thiol-specific antioxidant
protein, as an interacting partner of MIF. Association of MIF with PAG was
found in 293T cells transiently expressing MIF and PAG. The use of PAG mut
ants (C52S, C71S, and C173S) revealed that this association was significant
ly affected by C173S, but not C52S and C71S, indicating that a disulfide in
volving Cys(173) Of PAG is responsible for the formation of MIF.PAG complex
. In addition, the interaction was highly dependent on the reducing conditi
ons such as dithiothreitol or beta -mercaptoethanol but not in the presence
of H2O2. Analysis of the activities of the interacting proteins showed tha
t the D-dopachrome tautomerase activity of MIF was decreased in a dose-depe
ndent manner by coexpression of wild-type PAG, C52S, and C71S, whereas C173
S was almost ineffective, suggesting that the direct interaction may be inv
olved in the control of D-dopachrome tautomerase activity of MIF. Moreover,
MIF has been shown to bind to PAG and it also inhibits the antioxidant act
ivity of PAG.