Autophagy is an important internal nutrient source during starvation, while mechanistic target of rapamycin complex 1 (mTORC1) and the integrated stress response are two major signaling pathways that are responsive to nutrient availability and reprogram cellular processes accordingly.Although the regulation of autophagy by mTORC1 is well established, it remains unclear whether autophagy plays a role in modulating mTORC1 signaling and the integrated stress response.We herein demonstrated that in mouse C2C12 myotubes, under amino acid limited conditions, autophagy was induced and its release of amino acid was required for the preservation of mTORC1 activity.Inhibition of autophagy, either by bafilomycin A1 or chloroquine, abolished mTORC1 signaling activity under amino acid starvation, while inhibition of protein synthesis or amino acid supplementation could rescue mTORC1 activity under these conditions.We found that autophagy was required for maintaining the balance of both essential and nonessential amino acids during amino acid scarcity, while the ubiquitin-proteasome system only had a secondary role in sustaining mTORC1 activity.The integrated stress response, marked by the phosphorylation of eukaryotic initiation factor 2α (elF2cα), was induced by inhibition of autophagy independent of amino acid availability, which could be relieved by the induction of autophagy using mTOR inhibitor.Taken together, autophagy regulates mTORC1 and the integrated stress response pathway in an amino acid-dependent and-independent manner, respectively.