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TOR complex 2 (TORC2) in Dictyostelium suppresses phagocytic nutrient capture independently of TORC1-mediated

Daniel Rosel1, Taruna Khurana, Amit Majithia

  • 1Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-8028, USA.

Journal of Cell Science
|January 24, 2012
PubMed

Insights

Nutrient particle uptake (phagocytosis) in Dictyostelium is independent of TORC1 but enhanced by TORC2 inactivation. Macropinocytosis is not regulated by TOR complexes, highlighting TOR

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The Target of Rapamycin (TOR) kinase is a central regulator of cell growth and metabolism.
  • TOR functions in two distinct complexes: TORC1 and TORC2, with different roles in cellular processes.
  • Dictyostelium discoideum is a model organism for studying phagocytosis and cellular signaling.

Purpose of the Study:

  • To investigate the role of TORC1 and TORC2 in nutrient particle uptake (phagocytosis) and fluid uptake (macropinocytosis) in Dictyostelium.
  • To determine if TORC1-mediated nutrient sensing and growth regulation are involved in phagocytosis.
  • To elucidate the specific contributions of TORC2 components to phagocytosis regulation.

Main Methods:

  • Genetic manipulation of Dictyostelium strains to inactivate TORC1 and TORC2 components.
  • Quantitative analysis of phagocytosis and macropinocytosis rates.
  • Assessment of TORC1-mediated growth regulation pathways.

Main Results:

  • Phagocytosis of nutrient particles in Dictyostelium is independent of TORC1.
  • Inactivation of TORC2 components (Rictor/Pia, SIN1/RIP3, Lst8) significantly enhances the efficiency and speed of phagocytosis.
  • Macropinocytosis, an AKT-dependent process, is not regulated by either TORC1 or TORC2.

Conclusions:

  • TORC1 and TORC2 play distinct roles in nutrient uptake pathways in Dictyostelium.
  • TORC2 negatively regulates phagocytosis, while TORC1 is not involved in this process.
  • Balanced regulation of TORC1 and TORC2 is essential for coordinating growth, energy, and nutrient acquisition in Dictyostelium.

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