Activation of peroxisome proliferator-activated receptor-gamma pathway inhibits osteoclast differentiation.
The nuclear receptor and transcription factor, peroxisome proliferator-activated receptor-gamma (PPAR-gamma), regulates the activity of other transcription factors in the adipogenic differentiation and inflammatory response pathways. We examined the possible function of the PPAR-gamma pathway in osteoclast (Ocl) formation from CD34(+) hematopoietic stem cells (CD34(+) HSCs), using a co-culture system comprised of human mesenchymal stem cells (hMSCs) and CD34(+) HSCs, both derived from bone marrow. Ocl formation in this co-culture system is enhanced by the addition of exogenous osteoprotegerin ligand (OPGL), an essential Ocl differentiation factor, and macrophage-colony stimulating factor (M-CSF). The data indicate that soluble OPGL (sOPGL) and M-CSF stimulate Ocl formation in the co-cultures up to 4-fold compared with CD34(+) HSCs alone treated with sOPGL and M-CSF. CD34(+) HSCs, but not hMSCs, express PPAR-gamma, and 15-deoxy-Delta(12, 14)-prostaglandin-J2 (15d-PG-J2), a PPAR-gamma agonist, completely blocked the effects of sOPGL and M-CSF on Ocl formation and activity. The inhibitory effect of 15d-PG-J2 is specific to the Ocl lineage in both human and mouse models of osteoclastogenesis. Accordingly, parallel experiments demonstrate that sOPGL activates the NF-kappaB pathway within mouse Ocl progenitors, and this effect was abolished by 15d-PG-J2. These data establish a link between PPAR-gamma and OPGL signaling within Ocl progenitors, and support a role for PPAR-gamma pathway in the modulation of osteoclastogenesis.
Mbalaviele
G
G
Osiris Therapeutics, Inc., Baltimore, Maryland 21231, USA. gmbalaviele@osiristx.com
Abu-Amer
Y
Y
Meng
A
A
Jaiswal
R
R
Beck
S
S
Pittenger
M F
MF
Thiede
M A
MA
Marshak
D R
DR
D000818:Animals; D018952:Antigens, CD34 / Q000276:immunology; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008562:Membrane Glycoproteins / Q000378:metabolism; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists*; D015398:Signal Transduction; D014157:Transcription Factors / Q000819:agonists*
D018952:Antigens, CD34; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D014157:Transcription Factors