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The expanding TOR signaling network

Dietmar E Martin1, Michael N Hall

  • 1Division of Biochemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.

Current Opinion in Cell Biology
|March 23, 2005
PubMed

Insights

The target of rapamycin (TOR) pathway integrates nutrients, growth factors, and energy to control cell growth. New findings show TOR influences both cell-autonomous and distant cell growth, impacting organism size.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Cell growth is regulated by nutrient availability, growth factors, and cellular energy status.
  • The target of rapamycin (TOR) pathway is a central regulator integrating these signals to control cell growth.
  • Understanding TOR signaling is crucial for comprehending cell size control and organism development.

Purpose of the Study:

  • To elucidate the mechanisms by which the target of rapamycin (TOR) pathway integrates diverse cellular inputs to regulate cell growth.
  • To explore the cell-autonomous and non-cell-autonomous roles of TOR in determining cell, organ, and organism size.
  • To investigate the broader functions of TOR in growth-related processes like development, aging, and hypoxia response.

Main Methods:

  • Investigated upstream regulators of TOR, including AMPK, the TSC1-TSC2 complex, and Rheb.
  • Utilized findings from studies in yeast, mammals, and flies to analyze TOR signaling pathways.
  • Examined the identification and characterization of distinct TOR complexes (TORC1 and TORC2).

Main Results:

  • TOR integrates nutrient availability, growth factors, and energy status to control cell growth.
  • TOR signaling affects not only cell-autonomous growth but also the growth of distant cells, influencing overall organism size.
  • Two distinct TOR complexes, TORC1 and TORC2, have been identified in yeast and mammals, explaining signaling complexity.
  • TOR regulates diverse processes including development, aging, and response to hypoxia.

Conclusions:

  • The target of rapamycin (TOR) pathway is a key integrator of cellular signals controlling cell growth.
  • TOR signaling plays a critical role in both cell-autonomous and inter-cellular growth regulation, impacting organismal development.
  • TOR is a central component of a complex signaling network with broad implications for eukaryotic biology, including development and aging.

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