Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Sep;36(9):e22502.
doi: 10.1096/fj.202200591R.

Loading-induced bone formation is mediated by Wnt1 induction in osteoblast-lineage cells

Lisa Y Lawson  1   2 , Nicole Migotsky  1   2   3 , Christopher J Chermside-Scabbo  1   2   4 , John T Shuster  1   2 , Kyu Sang Joeng  5 , Roberto Civitelli  2   6 , Brendan Lee  7 , Matthew J Silva  1   2   3
Affiliations

Loading-induced bone formation is mediated by Wnt1 induction in osteoblast-lineage cells

Lisa Y Lawson et al. FASEB J. 2022 Sep.

Abstract

Mechanical loading on the skeleton stimulates bone formation. Although the exact mechanism underlying this process remains unknown, a growing body of evidence indicates that the Wnt signaling pathway is necessary for the skeletal response to loading. Recently, we showed that Wnts produced by osteoblast lineage cells mediate the osteo-anabolic response to tibial loading in adult mice. Here, we report that Wnt1 specifically plays a crucial role in mediating the mechano-adaptive response to loading. Independent of loading, short-term loss of Wnt1 in the Osx-lineage resulted in a decreased cortical bone area in the tibias of 5-month-old mice. In females, strain-matched loading enhanced periosteal bone formation in Wnt1F/F controls, but not in Wnt1F/F; OsxCreERT2 knockouts. In males, strain-matched loading increased periosteal bone formation in both control and knockout mice; however, the periosteal relative bone formation rate was 65% lower in Wnt1 knockouts versus controls. Together, these findings show that Wnt1 supports adult bone homeostasis and mediates the bone anabolic response to mechanical loading.

Keywords: Wnt signaling pathway; bone; mechanobiology; osteoblasts; osteocytes; osteogenesis.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.. Tibial loading increased Wnt1 expression in the bone.
Wnt1 mRNA expression was analyzed by RNAScope in situ hybridization after 5 days of loading. (A) Tibial Wnt1 expression was induced by loading in a Wnt1F/F male. Results representative of n=4. (B) Osteocytes were scored for Wnt1 expression at the site of peak compressive strain (lower panels).
Figure 2.
Figure 2.. Wnt1 was conditionally deleted in the Osx-expressing cells of adult mice.
(A) Five-month old Wnt1F/F (control) and OsxCreERT2; Wnt1F/F (knockout) mice were dosed with tamoxifen to induce Wnt1 deletion in the osteoblast lineage. (B-D) DNA recombination analysis indicated that Wnt1 (exon 2-4) deletion was specific to the tibias of OsxCreERT2-positive Wnt1F/F mice. (E) Tibial Wnt1 RNA expression was 78% lower in Wnt1 knockouts compared to controls. Individual data points and the mean ± std deviation are shown. n=3-6/group.
Figure 3.
Figure 3.. Cortical bone area decreased after short-term Wnt1 deletion.
The tibias of naïve male and female mice were serially scanned to determine the effects of short-term Wnt1 deletion on cortical bone morphometry. Tibias were μCT scanned before tamoxifen induction on Day 0, and again on Day 22. Individual data points and the mean ± std deviation are shown. n=3-6/group.
Figure 4.
Figure 4.. Loading-induced periosteal bone formation was blunted in Wnt1 knockout males.
Dynamic histomorphometry was used to analyze bone formation after 5 days of strain-matched loading. (A-C) Periosteal bone formation indices in males subjected to strain-matched loading (approximately −3000 μƐ). Loading increased periosteal bone formation in both groups, albeit to a lesser degree in Wnt1 knockouts. (D) Relative bone formation rate (rBFR/BS), used as a net index of loading-induced bone formation, was 65% less in Wnt1 knockouts relative to controls. n=9-11/genotype.
Figure 5.
Figure 5.. Loading-induced periosteal bone formation was blunted in Wnt1 knockout females.
(A-D) Control females were loaded to −9.2 N to engender a peak _target strain of −3040 μƐ. Strain-matched (SM) knockouts were loaded to −5.4 N to achieve a similar strain (−3200 μƐ), while force-matched (FM) knockouts were loaded to −9.2 N (approximately −5600 μƐ). (D) Comparison of the relative bone formation rates showed that the periosteal response to loading was 39% lower in force-matched knockouts relative to controls. n=7-10/genotype.
Figure 6.
Figure 6.. Loading-induced upregulation of bone formation genes was impaired in Wnt1 knockouts.
(A) Tibial loading potently induced Wnt1 expression in the bones of control but not knockout mice. (B-D) Loading-induced Bmp2, Col1a1, and Bglap upregulation was blunted in Wnt1 knockouts relative to strain-matched controls. n=4-5 per sex per genotype in each group for a total of n=9/genotype. Two-factor ANOVA was used to evaluate the effect of tibial loading (“Load)” and genotype (“Gen”), and their interaction (“Int”), on gene expression.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Robling AG, Niziolek PJ, Baldridge LA, Condon KW, Allen MR, Alam I, Mantila SM, Gluhak-Heinrich J, Bellido TM, Harris SE, Turner CH. Mechanical stimulation of bone in vivo reduces osteocyte expression of Sost/sclerostin. J Biol Chem. 2008. Feb 29;283(9):5866–75. doi: 10.1074/jbc.M705092200. Epub 2007 Dec 17 - DOI - PubMed
    1. Tu X, Rhee Y, Condon KW, et al. Sost downregulation and local Wnt signaling are required for the osteogenic response to mechanical loading. Bone. 2012;50(1):209–217. doi:10.1016/j.bone.2011.10.025 - DOI - PMC - PubMed
    1. Sawakami K, Robling AG, Ai M, Pitner ND, Liu D, Warden SJ, Li J, Maye P, Rowe DW, Duncan RL, Warman ML, Turner CH. The Wnt co-receptor LRP5 is essential for skeletal mechanotransduction but not for the anabolic bone response to parathyroid hormone treatment. J Biol Chem. 2006. Aug 18;281(33):23698–711. doi: 10.1074/jbc.M601000200. Epub 2006 Jun 20. - DOI - PubMed
    1. Saxon LK, Jackson BF, Sugiyama T, Lanyon LE, Price JS. Analysis of multiple bone responses to graded strains above functional levels, and to disuse, in mice in vivo show that the human Lrp5 G171V High Bone Mass mutation increases the osteogenic response to loading but that lack of Lrp5 activity reduces it. Bone. 2011. Aug;49(2):184–93. doi: 10.1016/j.bone.2011.03.683. Epub 2011 Mar 16. - DOI - PMC - PubMed
    1. Niziolek PJ, Farmer TL, Cui Y, Turner CH, Warman ML, Robling AG. High-bone-mass-producing mutations in the Wnt signaling pathway result in distinct skeletal phenotypes. Bone. 2011. Nov;49(5):1010–9. doi: 10.1016/j.bone.2011.07.034. Epub 2011 Aug 9. - DOI - PMC - PubMed

Publication types

LinkOut - more resources

  NODES
twitter 2