Osteoprotegerin ligand modulates murine osteoclast survival in vitro and in vivo.
Osteoprotegerin ligand (OPGL) targets osteoclast precursors and osteoclasts to enhance differentiation and activation, however, little is known about OPGL effects on osteoclast survival. In vitro, the combination of OPGL + colony-stimulating factor-1 (CSF-1) is required for optimal osteoclast survival. Ultrastructurally, apoptotic changes were observed in detached cells and culture lysates exhibited elevated caspase 3 activity, particularly in cultures lacking CSF-1. DEVD-FMK (caspase 3 inhibitor) partially protected cells when combined with OPGL, but not when used alone or in combination with CSF-1. CSF-1 maintained NF-kappaB activation and increased the expression of bcl-2 and bcl-X(L) mRNA, but had no effect on JNK activation. In contrast, OPGL enhanced both NF-kappaB and JNK kinase activation and increased the expression of c-src, but not bcl-2 and bcl-X(L) mRNA. These data suggest that aspects of both OPGL's and CSF-1's signaling/survival pathways are required for optimal osteoclast survival. In mice, a single dose of OPG, the OPGL decoy receptor, led to a >90% loss of osteoclasts because of apoptosis within 48 hours of exposure without impacting osteoclast precursor cells. Therefore, OPGL is essential, but not sufficient, for osteoclast survival and endogenous CSF-1 levels are insufficient to maintain osteoclast viability in the absence of OPGL.
Lacey
D L
DL
Departments of Pharmacology/Pathology, Cell Biology, Protein Chemistry, Mammalian Cell Molecular Biology, and Mammalian Genomics, Amgen, Inc., Thousand Oaks, California, USA. dlacey@amgen.com
Tan
H L
HL
Lu
J
J
Kaufman
S
S
Van
G
G
Qiu
W
W
Rattan
A
A
Scully
S
S
Fletcher
F
F
Juan
T
T
Kelley
M
M
Burgess
T L
TL
Boyle
W J
WJ
Polverino
A J
AJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D006023:Glycoproteins / Q000494:pharmacology; D007279:Injections, Subcutaneous; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008297:Male; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D051379:Mice; D008809:Mice, Inbred C3H; D016328:NF-kappa B / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects* / Q000648:ultrastructure; D053244:Osteoprotegerin; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D053245:RANK Ligand; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; D013997:Time Factors; D051020:bcl-X Protein
C494812:Bcl2l1 protein, mouse; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D053244:Osteoprotegerin; D019253:Proto-Oncogene Proteins c-bcl-2; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse; D051020:bcl-X Protein; D016173:Macrophage Colony-Stimulating Factor