Deleting Suppressor of Cytokine Signaling-3 in chondrocytes reduces bone growth by disrupting mitogen-activated protein kinase signaling

Osteoarthritis Cartilage. 2019 Oct;27(10):1557-1563. doi: 10.1016/j.joca.2019.05.018. Epub 2019 Jun 5.


Objective: To investigate the impact of deleting Suppressor of Cytokine Signaling (SOCS)-3 (SOCS3) in chondrocytes during murine skeletal development.

Method: Mice with a conditional Socs3 allele (Socs3fl/fl) were crossed with a transgenic mouse expressing Cre recombinase under the control of the type II collagen promoter (Col2a1) to generate Socs3Δ/Δcol2 mice. Skeletal growth was analyzed over the lifespan of Socs3Δ/Δcol2 mice and controls by detailed histomorphology. Bone size and cortical bone development was evaluated by micro-computed tomography (micro-CT). Growth plate (GP) zone width, chondrocyte proliferation and apoptosis were assessed by immunofluorescence staining for Ki67 and TUNEL. Fibroblast growth factor receptor-3 (FGFR3) signaling in the GP was assessed by immunohistochemistry, while the effect of SOCS3 overexpression on FGFR3-driven pMAPK signaling in HEK293T cells was evaluated by Western blot.

Results: Socs3Δ/Δcol2 mice of both sexes were consistently smaller compared to littermate controls throughout life. This phenotype was due to reduced long bone size, poor cortical bone development, reduced Ki67+ proliferative chondrocytes and decreased proliferative zone (PZ) width in the GP. Expression of pMAPK, but not pSTAT3, was increased in the GPs of Socs3Δ/Δcol2 mice relative to littermate controls. Overexpression of FGFR3 in HEK293T cells increased Fibroblast Growth Factor 18 (FGF18)-dependent Mitogen-activated protein kinase (MAPK) phosphorylation, while concomitant expression of SOCS3 reduced FGFR3 expression and abrogated MAPK signaling.

Conclusion: Our results suggest a potential role for SOCS3 in GP chondrocyte proliferation by regulating FGFR3-dependent MAPK signaling in response to FGF18.

Keywords: Bone and skeleton; Cartilage; Chondrocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Development / physiology*
  • Chondrocytes / physiology*
  • Female
  • Male
  • Mice
  • Mice, Transgenic
  • Mitogen-Activated Protein Kinases / physiology*
  • Signal Transduction
  • Suppressor of Cytokine Signaling 1 Protein / physiology*


  • Socs1 protein, mouse
  • Suppressor of Cytokine Signaling 1 Protein
  • Mitogen-Activated Protein Kinases