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Enrichment of Mammalian Tissues and Xenopus Oocytes with Cholesterol
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Cholesterol trafficking is required for mTOR activation in endothelial cells

Jing Xu1, Yongjun Dang, Yunzhao R Ren

  • 1Department of Pharmacology and Oncology, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.

Proceedings of the National Academy of Sciences of the United States of America
|February 24, 2010
PubMed

Insights

Cholesterol levels impact cell growth signaling. Blocking cholesterol transport to lysosomes inhibits mammalian target of rapamycin (mTOR) in endothelial cells, revealing a new pathway for anti-angiogenesis drug discovery.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Pharmacology

Background:

  • Mammalian target of rapamycin (mTOR) is a key regulator of cell growth and proliferation.
  • The influence of cholesterol homeostasis on mTOR signaling remains largely unexplored.

Purpose of the Study:

  • To investigate the effect of cholesterol homeostasis on mTOR activity in endothelial cells.
  • To explore the potential of targeting cholesterol trafficking pathways for anti-angiogenesis therapies.

Main Methods:

  • Utilized itraconazole to block lysosomal cholesterol trafficking.
  • Assessed mTOR activity inhibition and restoration via extracellular cholesterol.
  • Employed siRNA knockdown of Niemann-Pick disease type C (NPC) 1 and NPC2.
  • Investigated the effects of thapsigargin on cholesterol accumulation and mTOR inhibition.

Main Results:

  • Blockade of lysosomal cholesterol trafficking by itraconazole inhibited mTOR activity in endothelial cells.
  • mTOR inhibition by itraconazole was partially reversible with extracellular cholesterol.
  • Inhibitors of endosomal/lysosomal cholesterol transport and NPC1/NPC2 knockdown also reduced mTOR activity.
  • Thapsigargin reversed both lysosomal cholesterol accumulation and mTOR inhibition.

Conclusions:

  • mTOR signaling in endothelial cells appears to sense membrane sterol concentrations.
  • The cholesterol trafficking pathway represents a potential target for developing novel anti-angiogenesis agents.

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