mTOR: A Central Regulator of
Cell Proliferation, Angiogenesis,
and Cell Metabolism
mTOR is a kinase protein predominantly found in the cytoplasm of the cell. It acts as a central regulator of many biological processes that are essential for cell proliferation, angiogenesis, and cell metabolism.1-3 mTOR exerts its effects primarily by turning on and off the cell's translational machinery, which includes the ribosomes, and is responsible for protein synthesis.1
mTOR is a key intracellular point of convergence for a number of cellular signaling pathways. mTOR performs its regulatory function in response to activating or inhibitory signals transmitted through these pathways, which are located upstream from mTOR in the cell. These diverse signaling pathways are activated by a variety of growth factors (including vascular endothelial growth factors [VEGFs], platelet-derived growth factor [PDGF], epidermal growth factor [EGF], insulin-like growth factor 1 [IGF-1]), hormones (estrogen, progesterone), and the presence or absence of nutrients (glucose, amino acids) or oxygen.4,5
One or more of these signaling pathways may be abnormally activated in patients with many different types of cancer, resulting in deregulated cell proliferation, tumor angiogenesis, and abnormal cell metabolism.1,4,5
mTOR and cell orientation
Strong mTOR expression has also been observed in developing cortical neurons.6 mTOR regulates the expression of proteins that promote neuronal development and polarization in the developing brain.6,7
References
- Bjornsti et al. Nat Rev Cancer. 2004;4:335-348.
- Wullschleger et al. Cell. 2006;124:471-484.
- Pouysségur et al. Nature. 2006;441:437-443.
- Shaw et al. Nature. 2006;441:424-430.
- Faivre et al. Nat Rev Drug Disc. 2006;5:671-688.
- Li et al. J Neurosci. 2009;29:2334-2343.
- Choi et al. Genes Dev. 2008;22:2485-2495.