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Amino acid signaling in TOR activation

Joungmok Kim1, Kun-Liang Guan

  • 1Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, California 92093, USA. kuguan@ucsd.edu

Annual Review of Biochemistry
|May 10, 2011
PubMed

Insights

Amino acids (AA) are crucial for activating the target of rapamycin complex 1 (TORC1), a key regulator of cell growth implicated in cancer. Recent research highlights novel molecular players in this essential nutrient signaling pathway.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The target of rapamycin (TOR) pathway is a critical regulator of cell growth, proliferation, and metabolism, conserved across eukaryotes.
  • Dysregulation of TOR signaling, particularly TOR Complex 1 (TORC1), is frequently observed in various human cancers, making it a significant therapeutic target.
  • TORC1 integrates diverse cellular signals, including nutrients, energy status, and growth factors, to control protein synthesis and cell size.

Purpose of the Study:

  • To elucidate the molecular mechanisms by which amino acids (AA) signal to and activate TORC1.
  • To identify and characterize the key molecular components involved in AA-mediated TORC1 activation.
  • To understand how AA signaling integrates with other pathways, such as growth factor signaling, to regulate TORC1.

Main Methods:

  • Investigated the role of Rag GTPases in mediating amino acid signals to TORC1.
  • Utilized biochemical assays and cell-based experiments to identify protein kinases and nutrient transporters involved in the pathway.
  • Examined the contribution of intracellular trafficking machinery in relaying AA signals to TORC1.

Main Results:

  • Identified specific Rag GTPases as central mediators of amino acid-dependent TORC1 activation.
  • Uncovered the involvement of novel protein kinases and nutrient transporters in sensing and transmitting amino acid availability signals.
  • Demonstrated that the intracellular trafficking machinery plays a crucial role in the spatial organization and activation of TORC1 in response to amino acids.

Conclusions:

  • Amino acid signaling to TORC1 is a complex process involving a network of proteins including Rag GTPases, kinases, and transporters.
  • These molecular players relay nutrient status information to TORC1, ensuring appropriate cellular responses to nutrient availability.
  • Elucidating these AA signaling pathways provides new insights into cancer biology and potential therapeutic strategies targeting TORC1.

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