Expression of and role for ovarian cancer G-protein-coupled receptor 1 (OGR1) during osteoclastogenesis.
Osteoclasts differentiate from hematopoietic mononuclear precursor cells under the control of both colony stimulating factor-1 (CSF-1, or M-CSF) and receptor activator of NF-kappaB ligand (RANKL, or TRANCE, TNFSF11) to carry out bone resorption. Using high density gene microarrays, we followed gene expression changes in long bone RNA when CSF-1 injections were used to restore osteoclast populations in the CSF-1-null toothless (csf1(tl)/csf1(tl)) osteopetrotic rat. We found that ovarian cancer G-protein-coupled receptor 1 (OGR1, or GPR68) was strongly up-regulated, rising >6-fold in vivo after 2 days of CSF-1 treatments. OGR1 is a dual membrane receptor for both protons (extracellular pH) and lysolipids. Strong induction of OGR1 mRNA was also observed by microarray, real-time RT-PCR, and immunoblotting when mouse bone marrow mononuclear cells and RAW 264.7 pre-osteoclast-like cells were treated with RANKL to induce osteoclast differentiation. Anti-OGR1 immunofluorescence showed intense labeling of RANKL-treated RAW cells. The time course of OGR1 mRNA expression suggests that OGR1 induction is early but not immediate, peaking 2 days after inducing osteoclast differentiation both in vivo and in vitro. Specific inhibition of OGR1 by anti-OGR1 antibody and by small inhibitory RNA inhibited RANKL-induced differentiation of both mouse bone marrow mononuclear cells and RAW cells in vitro, as evidenced by a decrease in tartrate-resistant acid phosphatase-positive osteoclasts. Taken together, these data indicate that OGR1 is expressed early during osteoclastogenesis both in vivo and in vitro and plays a role in osteoclast differentiation.
Yang
Meiheng
M
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
Mailhot
Geneviève
G
Birnbaum
Mark J
MJ
MacKay
Carole A
CA
Mason-Savas
April
A
Odgren
Paul R
PR
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D016173:Macrophage Colony-Stimulating Factor / Q000008:administration & dosage; D051379:Mice; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D010010:Osteoclasts / Q000166:cytology / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics*; D010022:Osteopetrosis / Q000235:genetics / Q000378:metabolism / Q000628:therapy; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011922:Rats, Mutant Strains; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis* / Q000235:genetics* / Q000502:physiology
C486281:GPR68 protein, human; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D016173:Macrophage Colony-Stimulating Factor