Ribosomal protein S19 interacts with macrophage migration inhibitory factor and attenuates its pro-inflammatory function.
Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that has been implicated in the pathogenesis of inflammatory disorders such as infection, sepsis, and autoimmune disease. MIF exists preformed in cytoplasmic pools and exhibits an intrinsic tautomerase and oxidoreductase activity. MIF levels are elevated in the serum of animals and patients with infection or different inflammatory disorders. To elucidate how MIF actions are controlled, we searched for endogenous MIF-interacting proteins with the potential to interfere with key MIF functions. Using in vivo biotin-tagging and endogenous co-immunoprecipitation, the ribosomal protein S19 (RPS19) was identified as a novel MIF binding partner. Surface plasmon resonance and pulldown experiments with wild type and mutant MIF revealed a direct physical interaction of the two proteins (K(D) = 1.3 x 10(-6) m). As RPS19 is released in inflammatory lesions by apoptotic cells, we explored whether it affects MIF function and inhibits its binding to receptors CD74 and CXCR2. Low doses of RPS19 were found to strongly inhibit MIF-CD74 interaction. Furthermore, RPS19 significantly compromised CXCR2-dependent MIF-triggered adhesion of monocytes to endothelial cells under flow conditions. We, therefore, propose that RPS19 acts as an extracellular negative regulator of MIF.
Filip
Ana-Maria
AM
Department of Anatomy and Cell Biology, Unit of Reproductive Biology, Medical Clinic II, and Department of Biochemistry, Justus-Liebig-University of Giessen, Giessen D-35385, Germany.
Klug
Jörg
J
Cayli
Sevil
S
Fröhlich
Suada
S
Henke
Tamara
T
Lacher
Philipp
P
Eickhoff
Regina
R
Bulau
Patrick
P
Linder
Monika
M
Carlsson-Skwirut
Christine
C
Leng
Lin
L
Bucala
Richard
R
Kraemer
Sandra
S
Bernhagen
Jürgen
J
Meinhardt
Andreas
A
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001327:Autoimmune Diseases / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion / Q000235:genetics; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism; D008263:Macrophage Migration-Inhibitory Factors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009000:Monocytes / Q000378:metabolism*; D009154:Mutation; D041681:NIH 3T3 Cells; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D051381:Rats; D023063:Receptors, Interleukin-8B / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D018805:Sepsis / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance
D008263:Macrophage Migration-Inhibitory Factors; D023063:Receptors, Interleukin-8B; D012269:Ribosomal Proteins; C040343:ribosomal protein S19; D010088:Oxidoreductases