Sclerostin stimulates osteocyte support of osteoclast activity by a RANKL-dependent pathway

Asiri R. Wijenayaka, Masakazu Kogawa, Hui Peng Lim, Lynda Bonewald, David M. Findlay, Gerald J. Atkins

Research output: Contribution to journalArticle

229 Citations (Scopus)

Abstract

Sclerostin is a product of mature osteocytes embedded in mineralised bone and is a negative regulator of bone mass and osteoblast differentiation. While evidence suggests that sclerostin has an anti-anabolic role, the possibility also exists that sclerostin has catabolic activity. To test this we treated human primary pre-osteocyte cultures, cells we have found are exquisitely sensitive to sclerostin, or mouse osteocyte-like MLO-Y4 cells, with recombinant human sclerostin (rhSCL) and measured effects on pro-catabolic gene expression. Sclerostin dose-dependently up-regulated the expression of receptor activator of nuclear factor kappa B (RANKL) mRNA and down-regulated that of osteoprotegerin (OPG) mRNA, causing an increase in the RANKL:OPG mRNA ratio. To examine the effects of rhSCL on resulting osteoclastic activity, MLO-Y4 cells plated onto a bone-like substrate were primed with rhSCL for 3 days and then either mouse splenocytes or human peripheral blood mononuclear cells (PBMC) were added. This resulted in cultures with elevated osteoclastic resorption (approximately 7-fold) compared to untreated co-cultures. The increased resorption was abolished by co-addition of recombinant OPG. In co-cultures of MLO-Y4 cells with PBMC, SCL also increased the number and size of the TRAP-positive multinucleated cells formed. Importantly, rhSCL had no effect on TRAP-positive cell formation from monocultures of either splenocytes or PBMC. Further, rhSCL did not induce apoptosis of MLO-Y4 cells, as determined by caspase activity assays, demonstrating that the osteoclastic response was not driven by dying osteocytes. Together, these results suggest that sclerostin may have a catabolic action through promotion of osteoclast formation and activity by osteocytes, in a RANKL-dependent manner.

Original languageEnglish (US)
Article numbere25900
JournalPLoS One
Volume6
Issue number10
DOIs
StatePublished - Oct 4 2011
Externally publishedYes

Fingerprint

Osteoprotegerin
Osteocytes
osteoclasts
Osteoclasts
Bone
Blood
Messenger RNA
Receptor Activator of Nuclear Factor-kappa B
mononuclear leukocytes
Osteoblasts
Blood Cells
Caspases
Cell culture
Gene expression
bones
resorption
coculture
cells
splenocytes
Coculture Techniques

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Sclerostin stimulates osteocyte support of osteoclast activity by a RANKL-dependent pathway. / Wijenayaka, Asiri R.; Kogawa, Masakazu; Lim, Hui Peng; Bonewald, Lynda; Findlay, David M.; Atkins, Gerald J.

In: PLoS One, Vol. 6, No. 10, e25900, 04.10.2011.

Research output: Contribution to journalArticle

Wijenayaka, Asiri R. ; Kogawa, Masakazu ; Lim, Hui Peng ; Bonewald, Lynda ; Findlay, David M. ; Atkins, Gerald J. / Sclerostin stimulates osteocyte support of osteoclast activity by a RANKL-dependent pathway. In: PLoS One. 2011 ; Vol. 6, No. 10.
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