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Chondrocyte autophagy is stimulated by HIF-1 dependent AMPK activation and mTOR suppression

Jolene Bohensky1, Serge Leshinsky, Vickram Srinivas

  • 1Department of Orthopedic Surgery, Thomas Jefferson University, Philadelphia, PA 19107, USA.

Pediatric Nephrology (Berlin, Germany)
|October 16, 2009
PubMed

Insights

Chondrocyte survival involves autophagy, regulated by AMP-activated Protein Kinase (AMPK) and Hypoxia-Inducible Factor-1 (HIF-1). AMPK activation is crucial for autophagy induction, particularly under stress, ensuring chondrocyte survival.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Chondrocytes are crucial for cartilage maintenance.
  • Cellular energy status and stress responses impact chondrocyte survival.
  • Autophagy plays a vital role in cellular homeostasis.

Purpose of the Study:

  • To investigate the interplay between Hypoxia-Inducible Factor-1 (HIF-1), AMP-activated Protein Kinase (AMPK), and mammalian Target of Rapamycin (mTOR) in chondrocyte survival and autophagy.
  • To elucidate the role of AMPK in regulating autophagy in chondrocytes.

Main Methods:

  • Analysis of AMPK expression and activation during chondrocyte maturation.
  • Thapsigargin treatment to induce stress and assess HIF-1 dependent responses.
  • AMPK silencing in serum-starved cells to evaluate its necessity for autophagy.
  • Inhibition of AMPK in mTOR-silenced cells to differentiate signaling pathways.

Main Results:

  • Chondrocytes express functional AMPK, with activation increasing during maturation.
  • Thapsigargin treatment induced AMPK and autophagy in a HIF-1 dependent manner.
  • AMPK is essential for the induction of autophagy in serum-starved chondrocytes.
  • mTOR suppression induced autophagy independently of AMPK activity.

Conclusions:

  • Autophagy is activated in chondrocytes via an AMPK-dependent pathway, regulated by HIF-1, in response to micro-environmental changes.
  • AMPK signaling is a key mediator of autophagy in chondrocytes, contributing to their survival under stress.

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