Nutrient regulation of the mTOR complex 1 signaling pathway.

The mammalian target of rapamycin (mTOR) is an evolutionally conserved kinase which exists in two distinct structural and functional complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Of the two complexes, mTORC1 couples nutrient abundance to cell growth and proliferation by sensing and integrating a variety of inputs arising from amino acids, cellular stresses, energy status, and growth factors. Defects in mTORC1 regulation are implicated in the development of many metabolic diseases, including cancer and diabetes. Over the past decade, significant advances have been made in deciphering the complexity of the signaling processes contributing to mTORC1 regulation and function, but the mechanistic details are still not fully understood. In particular, how amino acid availability is sensed by cells and signals to mTORC1 remains unclear. In this review, we discuss the current understanding of nutrient-dependent control of mTORC1 signaling and will focus on the key components involved in amino acid signaling to mTORC1.