| First Author | Koskinen C | Year | 2013 |
| Journal | J Biol Chem | Volume | 288 |
| Issue | 41 | Pages | 29333-44 |
| PubMed ID | 23990469 | Mgi Jnum | J:204546 |
| Mgi Id | MGI:5532789 | Doi | 10.1074/jbc.M113.494591 |
| Citation | Koskinen C, et al. (2013) Lack of CD47 impairs bone cell differentiation and results in an osteopenic phenotype in vivo due to impaired signal regulatory protein alpha (SIRPalpha) signaling. J Biol Chem 288(41):29333-44 |
| abstractText | Here, we investigated whether the cell surface glycoprotein CD47 was required for normal formation of osteoblasts and osteoclasts and to maintain normal bone formation activity in vitro and in vivo. In parathyroid hormone or 1alpha,25(OH)2-vitamin D3 (D3)-stimulated bone marrow cultures (BMC) from CD47(-/-) mice, we found a strongly reduced formation of multinuclear tartrate-resistant acid phosphatase (TRAP)(+) osteoclasts, associated with reduced expression of osteoclastogenic genes (nfatc1, Oscar, Trap/Acp, ctr, catK, and dc-stamp). The production of M-CSF and RANKL (receptor activator of nuclear factor kappabeta ligand) was reduced in CD47(-/-) BMC, as compared with CD47(+/+) BMC. The stromal cell phenotype in CD47(-/-) BMC involved a blunted expression of the osteoblast-associated genes osterix, Alp/Akp1, and alpha-1-collagen, and reduced mineral deposition, as compared with that in CD47(+/+) BMC. CD47 is a ligand for SIRPalpha (signal regulatory protein alpha), which showed strongly reduced tyrosine phosphorylation in CD47(-/-) bone marrow stromal cells. In addition, stromal cells lacking the signaling SIRPalpha cytoplasmic domain also had a defect in osteogenic differentiation, and both CD47(-/-) and non-signaling SIRPalpha mutant stromal cells showed a markedly reduced ability to support osteoclastogenesis in wild-type bone marrow macrophages, demonstrating that CD47-induced SIRPalpha signaling is critical for stromal cell support of osteoclast formation. In vivo, femoral bones of 18- or 28-week-old CD47(-/-) mice showed significantly reduced osteoclast and osteoblast numbers and exhibited an osteopenic bone phenotype. In conclusion, lack of CD47 strongly impairs SIRPalpha-dependent osteoblast differentiation, deteriorate bone formation, and cause reduced formation of osteoclasts. |
