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Rheb and Rags come together at the lysosome to activate mTORC1

Marlous J Groenewoud1, Fried J T Zwartkruis

  • 1Molecular Cancer Research, Centre for Biomedical Genetics and Cancer Genomics Centre, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.

Biochemical Society Transactions
|July 19, 2013
PubMed

Insights

Amino acids regulate cell growth by activating mTORC1 (mammalian target of rapamycin complex 1). This study explores how amino acids and GTPases like Rheb and Rags control mTORC1 localization and function.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • mTORC1 (mammalian target of rapamycin complex 1) is a key regulator of cell growth and metabolism.
  • Its activity is controlled by GTPases, primarily Rheb and the Rag GTPases, and is dependent on amino acid availability.
  • Rag GTPases recruit mTORC1 to lysosomes via the Ragulator complex in an amino-acid-dependent manner.

Purpose of the Study:

  • To provide an overview of novel mechanisms by which amino acids influence Rag GTPase function.
  • To postulate a model for Rheb activation and localization in response to amino acids.
  • To explore the potential role of endosome-lysosome maturation in mTORC1 activation.

Main Methods:

  • Literature review and synthesis of existing research on mTORC1 regulation.
  • Analysis of the roles of Rheb, Rag GTPases, and the Ragulator complex.
  • Postulation of a model for Rheb activation and transport.

Main Results:

  • Amino acids are essential for mTORC1 activity, with Rag GTPases mediating lysosomal localization.
  • Rheb, responsive to growth factors and PLD1 (phospholipase D1), also contributes to amino acid-stimulated mTORC1 activation.
  • A novel hypothesis suggests Rheb is activated at the Golgi and travels to lysosomes.

Conclusions:

  • Amino acid availability dictates mTORC1 activity through Rheb and Rag GTPase-mediated lysosomal recruitment.
  • Endosome maturation to lysosomes may be crucial for maintaining GTP-bound Rheb supply for sustained mTORC1 activation.
  • This process might be a feedback loop, where mTORC1 activation drives lysosome maturation.

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