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 bio-signaling 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.