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Real-time Visualization and Analysis of Chondrocyte Injury Due to Mechanical Loading in Fully Intact Murine Cartilage Explants
08:42

Real-time Visualization and Analysis of Chondrocyte Injury Due to Mechanical Loading in Fully Intact Murine Cartilage Explants

Published on: January 7, 2019

Akt phosphorylation in human chondrocytes is regulated by p53R2 in response to mechanical stress

K Kawakita1, T Nishiyama, T Fujishiro

  • 1Department of Orthopedic Surgery, Kobe University Graduate School of Medicine, 7-5-2 Kusunokicho, Chuo-ku, Kobe, Japan.

Osteoarthritis and Cartilage
|September 8, 2012
PubMed
Abstract

Insights

The tumor suppressor p53R2 is upregulated by mechanical stress in chondrocytes. Its downregulation may offer a novel therapeutic strategy for osteoarthritis (OA) by regulating matrix synthesis.

Area of Science:

  • Cell biology
  • Biochemistry
  • Biomedical engineering

Background:

  • p53R2, a tumor-suppressor protein, is activated by cellular stressors.
  • p53R2 production is induced by DNA damage and subsequent p53 phosphorylation.
  • The specific role of p53R2 in chondrocytes, particularly under mechanical stress, is not well understood.

Purpose of the Study:

  • To investigate p53R2 expression and its regulation in chondrocytes subjected to mechanical stress.
  • To explore the function of p53R2 in chondrocyte mechanotransduction.
  • To assess the impact of p53R2 on matrix synthesis and signaling pathways.

Main Methods:

  • Immunohistochemistry, western blotting, and real-time PCR were used to measure p53R2 expression in osteoarthritis (OA) and normal cartilage.
  • Chondrocytes were subjected to cyclical tensile strain using a Flexercell system.
  • Sulfated glycosaminoglycan (sGAG) production and protein/mRNA levels of matrix components were quantified. Signaling pathway activation (Akt, p38MAPK, ERK1/2, JNK) was assessed via western blotting.

Main Results:

  • p53R2 expression was significantly elevated in OA chondrocytes and in chondrocytes exposed to mechanical strain.
  • Mechanical strain led to decreased Akt phosphorylation in OA chondrocytes, while p53R2 transfection increased it.
  • p53R2 upregulation, following siRNA transfection under strain, enhanced sGAG, collagen type II, and aggrecan mRNA expression.

Conclusions:

  • p53R2 plays a role in regulating matrix synthesis through Akt phosphorylation in chondrocyte mechanotransduction.
  • Down-regulation of p53R2 presents a potential therapeutic avenue for osteoarthritis.
  • Understanding p53R2's role in mechanotransduction could inform OA treatment strategies.

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