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Peroxisome proliferator-activated receptor γ coactivator 1α and FoxO3A mediate chondroprotection by AMP-activated

Xianling Zhao1, Freyr Petursson, Benoit Viollet

  • 1VA San Diego Medical Center and University of California, San Diego.

Arthritis & Rheumatology (Hoboken, N.J.)
|July 23, 2014
PubMed
Abstract

Insights

AMP-activated protein kinase (AMPK) activation protects chondrocytes by upregulating peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and FoxO3A. These key targets reduce oxidative stress and limit cartilage damage in osteoarthritis (OA).

Area of Science:

  • Cell Biology
  • Biochemistry
  • Osteoarthritis Research

Background:

  • AMP-activated protein kinase (AMPK) plays a crucial role in inhibiting chondrocyte procatabolic responses.
  • Inflammation and biomechanical injury trigger detrimental responses in chondrocytes.
  • Understanding AMPK's downstream targets is key to developing chondroprotective strategies.

Purpose of the Study:

  • To investigate whether peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and FoxO3A mediate the chondroprotective effects of AMPK activation.
  • To elucidate the role of PGC-1α and FoxO3A in regulating oxidative stress and procatabolic responses in chondrocytes.

Main Methods:

  • Assessed AMPK activity and expression of PGC-1α and FoxO3A in human and mouse chondrocytes using Western blotting and immunohistochemistry.
  • Utilized small interfering RNA and plasmid DNA to knockdown or overexpress PGC-1α and FoxO3A.
  • Measured mitochondrial superoxide generation using MitoSOX Red and analyzed NF-κB phosphorylation.

Main Results:

  • AMPK activation enhanced PGC-1α and FoxO3A expression, while their expression was reduced in osteoarthritis cartilage.
  • Knockdown of PGC-1α and FoxO3A diminished the inhibitory effects of AMPK activation on procatabolic responses.
  • Overexpression of PGC-1α and FoxO3A increased antioxidant enzyme expression (SOD2, catalase) and inhibited menadione-induced superoxide generation.

Conclusions:

  • PGC-1α and FoxO3A are critical mediators of AMPK's chondroprotective effects by limiting oxidative stress.
  • These targets play a significant role in blocking procatabolic responses in chondrocytes.
  • Targeting PGC-1α and FoxO3A presents a potential therapeutic strategy to inhibit osteoarthritis progression.

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