RANK ligand and interferon gamma differentially regulate cathepsin gene expression in pre-osteoclastic cells.
Receptor activator of NF-kappaB ligand (RANKL) and interferon gamma (IFN-gamma) are critical and opposing mediators of osteoclastogenesis, exerting stimulatory and inhibitory effects, respectively. Cathepsin K (CTSK) is a secreted protease that plays an essential role in osteoclastic bone resorption. We have examined the role of IFN-gamma in the regulation of CTSK expression in the murine monocytic RAW 264.7 cell line, which can be readily differentiated to bone-resorbing osteoclasts upon RANKL treatment. Real-time RT-PCR reveals that RANKL stimulates CTSK mRNA expression in a dose- and time-dependent fashion, but that RANKL does not alter the expression of cathepsin L (CTSL) and cathepsin S (CTSS) mRNA. IFN-gamma stimulates both CTSL and CTSS expression after 3 days, but fails to significantly alter CTSK expression. IFN-gamma markedly inhibits the stimulation of CTSK mRNA and protein by RANKL, whereas RANKL suppresses the stimulation of CTSL and CTSS mRNA by IFN-gamma. IFN-gamma also ablates the RANKL induced osteoclastic differentiation of RAW cells. In RAW cells stably transfected with a CTSK promoter-luciferase plasmid containing the 1618 bp upstream of the transcription initiation site, IFN-gamma inhibits CTSK promoter activity and ablates its induction by RANKL. In conclusion, IFN-gamma and RANKL differentially regulate cathepsin K, S, and L gene expression in pre-osteoclastic cells, and there appears to be significant cross talk between the signal transduction pathways mediating the responses to RANKL and IFN-gamma.
Pang
Manhui
M
Geriatric Research, Education, and Clinical Center, and Research Service, Miami Veterans Affairs Medical Center, Miami, FL 33125, USA.
Martinez
Ariel F
AF
Jacobs
Jay
J
Balkan
Wayne
W
Troen
Bruce R
BR
D000818:Animals; D002352:Carrier Proteins / Q000494:pharmacology*; D002403:Cathepsins / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D007371:Interferon-gamma / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D051379:Mice; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D007371:Interferon-gamma; D002403:Cathepsins