Studies into the mechanism of action of rapamycin, a potent anti- proliferative drug, have led to the discovery of a novel translational control pathway with critical roles in eukaryotic cell division. The central component of the pathway is the in vivo target of rapamycin, a protein that we call RAFT1 but is also known as FRAP or mTOR. RAFT1 is a large protein kinase related to the cell-cycle regulators ataxia telangiectasia mutated (ATM) and DNA-dependent protein kinase (DNA-PKcs). The RAFT1 mechanism of action is poorly understood, but the anti- proliferative properties of rapamycin reveal an essential, drug- sensitive role in cell division for the RAFT1-mediated translation of specific mRNAs. To elucidate how RAFT1 regulates mRNA translation and cell cycle progression we propose to: (1) identify downstream components of the RAFT1 signaling pathway, (2) understand their in vivo function in RAFT1 signaling, and (3) identify the rapamycin- sensitive mRNAs whose translational inhibition leads to cell cycle arrest. We are taking two approaches to discover components of the pathway: a biochemical one to identify functionally important RAFT1 interacting proteins (RIPs) and a genetic one for suppressors of the anti-proliferative effects of rapamycin. We have already identified two components whose role in RAFT1 signaling we will analyze in detail: p60, a novel RIP that may regulate downstream stages of the pathway, and FRAT1, an oncogene whose overexpression, we have shown, confers resistance to the anti-proliferative effects of rapamycin. We have used a microarray-based strategy to identify mRNAs whose translation is inhibited by rapamycin in T-cells. With biochemical and genetic experiments we will determine how RAFT1 controls the translation of these mRNAs and address why their inhibition leads to cell cycle arrest. The anti-proliferative effects of rapamycin are of medical value and the drug is now in clinical trials for immunosuppressive and anti-cancer uses. Thus, our study of the RAFT1 signaling pathway will not only elucidate the workings of a critical regulator of cell division, but also explain how a clinically useful drug exerts its effects.
| Abu-Remaileh, Monther; Wyant, Gregory A; Kim, Choah et al. (2017) Lysosomal metabolomics reveals V-ATPase- and mTOR-dependent regulation of amino acid efflux from lysosomes. Science 358:807-813 |
| Ersching, Jonatan; Efeyan, Alejo; Mesin, Luka et al. (2017) Germinal Center Selection and Affinity Maturation Require Dynamic Regulation of mTORC1 Kinase. Immunity 46:1045-1058.e6 |
| Wolfson, Rachel L; Sabatini, David M (2017) The Dawn of the Age of Amino Acid Sensors for the mTORC1 Pathway. Cell Metab 26:301-309 |
| Caron, Alexandre; Mouchiroud, Mathilde; Gautier, Nicolas et al. (2017) Loss of hepatic DEPTOR alters the metabolic transition to fasting. Mol Metab 6:447-458 |
| Kalaitzidis, Demetrios; Lee, Dongjun; Efeyan, Alejo et al. (2017) Amino acid-insensitive mTORC1 regulation enables nutritional stress resilience in hematopoietic stem cells. J Clin Invest 127:1405-1413 |
| Chantranupong, Lynne; Scaria, Sonia M; Saxton, Robert A et al. (2016) The CASTOR Proteins Are Arginine Sensors for the mTORC1 Pathway. Cell 165:153-164 |
| Saxton, Robert A; Knockenhauer, Kevin E; Wolfson, Rachel L et al. (2016) Structural basis for leucine sensing by the Sestrin2-mTORC1 pathway. Science 351:53-8 |
| Saxton, Robert A; Chantranupong, Lynne; Knockenhauer, Kevin E et al. (2016) Mechanism of arginine sensing by CASTOR1 upstream of mTORC1. Nature 536:229-33 |
| Wolfson, Rachel L; Chantranupong, Lynne; Saxton, Robert A et al. (2016) Sestrin2 is a leucine sensor for the mTORC1 pathway. Science 351:43-8 |
| Chen, Walter W; Freinkman, Elizaveta; Wang, Tim et al. (2016) Absolute Quantification of Matrix Metabolites Reveals the Dynamics of Mitochondrial Metabolism. Cell 166:1324-1337.e11 |
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