title: TOR complex 2 (TORC2) in Dictyostelium suppresses phagocytic nutrient capture independently of TORC1-mediated nutrient sensing.
abstract: The TOR protein kinase functions in two distinct complexes, TOR complex 1 (TORC1) and 2 (TORC2). TORC1 is required for growth in response to growth factors, nutrients and the cellular energy state; TORC2 regulates AKT signaling, which can modulate cytoskeletal polarization. In its ecological niche, Dictyostelium engulf bacteria and yeast for nutrient capture. Despite the essential role of TORC1 in control of cellular growth, we show that nutrient particle capture (phagocytosis) in Dictyostelium is independent of TORC1-mediated nutrient sensing and growth regulation. However, loss of Dictyostelium TORC2 components Rictor/Pia, SIN1/RIP3 and Lst8 promotes nutrient particle uptake; inactivation of TORC2 leads to increased efficiency and speed of phagocytosis. In contrast to phagocytosis, we show that macropinocytosis, an AKT-dependent process for cellular uptake of fluid phase nutrients, is not regulated by either of the TOR complexes. The integrated and balanced regulation of TORC1 and TORC2 might be crucial in Dictyostelium to coordinate growth and energy needs with other essential TOR-regulated processes.
authors.affiliation: Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-8028,  USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rosel
authors.forename: Taruna
authors.initials: T
authors.lastname: Khurana
authors.forename: Amit
authors.initials: A
authors.lastname: Majithia
authors.forename: Xiuli
authors.initials: X
authors.lastname: Huang
authors.forename: Ramanath
authors.initials: R
authors.lastname: Bhandari
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kimmel
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D004023:Dictyostelium / Q000254:growth & development / Q000378:metabolism*; D005502:Food; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000378:metabolism*; D010448:Peptide Initiation Factors / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D010873:Pinocytosis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D013997:Time Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D046912:Multiprotein Complexes; D010448:Peptide Initiation Factors; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus