Expression and function of RANK in human monocyte chemotaxis.
OBJECTIVE
RANKL, a member of the tumor necrosis factor superfamily, is a central regulator of osteoclast recruitment and activation. Whether RANKL affects monocyte locomotion in vitro via RANK and a possible signaling pathway were investigated.


METHODS
Monocytes were obtained from venous blood of healthy donors. Cell migration was studied by micropore filter assays. The signaling mechanisms required for RANKL-dependent migration were tested using signaling enzyme blockers and Western blot analyses. Expression of RANK messenger RNA (mRNA) in monocytes was demonstrated by reverse transcriptase-polymerase chain reaction, and receptor expression on cell surface was investigated by fluorescence-activated cell sorting analyses.


RESULTS
RANKL significantly stimulated monocyte chemotaxis via activation of phosphatidylinositol 3-kinase, phosphodiesterase, and Src kinase. The effect on migration was inhibited by osteoprotegerin, which is the decoy receptor for RANKL. Expression of RANK receptor mRNA was shown, and synthesis of RANK in monocytes was suggested by the detection of RANK immunoreactivity on the cell surface.


CONCLUSIONS
These data suggest that RANK is expressed by monocytes whose activation by RANKL stimulates directed migration involving phosphatidylinositol 3-kinase, phosphodiesterase, and Src kinases.
Mosheimer
Birgit A
BA
University of Innsbruck, Innsbruck, Austria.
Kaneider
Nicole C
NC
Feistritzer
Clemes
C
Sturn
Daniel H
DH
Wiedermann
Christian J
CJ
D002352:Carrier Proteins / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000502:physiology*; D004789:Enzyme Activation; D004798:Enzymes / Q000502:physiology; D006023:Glycoproteins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D006801:Humans; D007425:Intracellular Membranes / Q000201:enzymology; D008562:Membrane Glycoproteins / Q000494:pharmacology; D009000:Monocytes / Q000378:metabolism / Q000502:physiology*; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism / Q000502:physiology*; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D019061:src-Family Kinases / Q000378:metabolism
D002352:Carrier Proteins; D004798:Enzymes; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human; D019061:src-Family Kinases