Distinct roles of the mTOR components Rictor and Raptor in MO7e megakaryocytic cells
Autor: | Sandra Olthof, Monika R. Tyl, Edo Vellenga, Gwenny M. Fuhler, A. Lyndsay Drayer, Nel R. Blom |
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Přispěvatelé: | Guided Treatment in Optimal Selected Cancer Patients (GUTS), Stem Cell Aging Leukemia and Lymphoma (SALL) |
Jazyk: | angličtina |
Rok vydání: | 2009 |
Předmět: |
Programmed cell death
KINASE-B Genetic Vectors Green Fluorescent Proteins INHIBITION Bone Marrow Cells mTORC1 Biology Mechanistic Target of Rapamycin Complex 1 mTORC2 Rictor ACTIVATION Humans Progenitor cell RNA Small Interfering PHOSPHORYLATION PI3K/AKT/mTOR pathway Adaptor Proteins Signal Transducing Cell Proliferation PROGENITORS Cell growth TOR Serine-Threonine Kinases RPTOR THROMBOPOIETIN-INDUCED PROLIFERATION Proteins Hematology General Medicine Regulatory-Associated Protein of mTOR Flow Cytometry CD34(+) CELLS Cell biology Raptor Intracellular signal transduction Phosphotransferases (Alcohol Group Acceptor) Rapamycin-Insensitive Companion of mTOR Protein Gene Expression Regulation MAMMALIAN TARGET RIBOSOMAL-PROTEIN S6 Multiprotein Complexes Carrier Proteins RAPAMYCIN Megakaryocytes megakaryopoiesis signal transduction Transcription Factors |
Zdroj: | European Journal of Haematology, 83(3), 235-245. Wiley |
ISSN: | 0902-4441 |
DOI: | 10.1111/j.1600-0609.2009.01263.x |
Popis: | Objective:During megakaryopoiesis, hematopoietic progenitor cells in the bone marrow proliferate and ultimately differentiate in mature megakaryocytes (MK). We and others have recently described a role for the mammalian target of Rapamycin (mTOR) in proliferation and differentiation of MK cells. Two non-redundant complexes of mTOR have been described; mTORC1 containing rapamycin-associated TOR protein (Raptor) and mTORC2 containing Rapamycin-insensitive companion of mTOR (Rictor). The individual roles of these complexes in MK development have so far not been elucidated, and were investigated in this study.Methods:We have used an siRNA approach to selectively knock down either Rictor or Raptor expression in MO7e megakaryoblastic cells. Using flow cytometry, nuclear ploidity, and cell cycling as assessed by BrdU incorporation were investigated. Electron microscopy and cotransductions with GFP-LC3 were used to quantify autophagy. Activation of intracellular signal transduction pathways was studied by Western blot analysis.Results:We observed a reduced cell cycling upon Rictor siRNA transduction, resulting in decreased numbers of polypoid cells. Knocking down Raptor expression resulted in a reduced expansion and a reduced cell size. In addition, increased autophagy was observed in Raptor siRNA-transduced cells, in correspondence with an attenuation of activation of the p70S6K/S6, and 4E-BP pathways.Conclusions:The current study shows that the mTORC1 and mTORC2 complexes have distinct, non-redundant functions in MO7e MK cell proliferation, and development. The mTOR/Rictor complex affects megakaryopoiesis by regulating nuclear division and subsequent cell cycle progression, whereas Raptor signaling protects MK cells from autophagic cell death, enabling normal megakaryopoiesis to take place. |
Databáze: | OpenAIRE |
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