Recent advances in understanding of amino acid signaling to mTORC1 activation

The mechanistic target of rapamycin complex 1 (mTORC1) is a master controller of cell growth and metabolism which integrates diverse biosignaling inputs to coordinate various fundamental biological processes. Amino acids, especially leucine, arginine and glutamine, signal to mTORC1 activation. Classically, Rag GTPases play a crucial role in amino acids-induced mTORC1 activation in the lysosome and Golgi apparatus. More recently, multiple amino acid sensors have been identified and most of them indirectly associate with Rag GTPases. As a result, the mechanistic details on how amino acids are sensed and activate mTORC1 are rapidly evolving. This review discusses current understanding of mTORC1 activation and provides a brief and up-to-date narrative on the progress of amino acid sensors regulating mTORC1 activation.