Sphingolipids integrate TORC2 with TORC1 through vacuolar liquid-ordered domain formation

The coordination of multiple signaling pathways across different compartments of the endomembrane system is essential for cellular adaptation to the environment; however, the underlying mechanisms remain poorly understood. Previous studies have described the existence of sterol-enriched liquid-ordered (Lo) domains in the vacuole membrane of yeast, which act as platforms for signal initiation. Here, we demonstrate that vacuolar Lo domains serve as signaling platforms for the evolutionarily conserved Target of Rapamycin Complex 1 (TORC1) kinase complex. Notably, we show that TORC2, which is functionally distinct from TORC1 and localized to the plasma membrane, regulates TORC1 activity through sphingolipid metabolism and subsequent vacuolar Lo domain formation. Collectively, our findings reveal a lipid domain-mediated network that integrates two signaling pathways originating from spatially different cellular sites. HIGHLIGHTSO_LIDecreased sphingolipid levels cause characteristic phenotypes that reflect low TORC1 activity. C_LIO_LISphingolipid-enriched vacuolar Lo domains are required for the EGO complex-mediated activation of TORC1. C_LIO_LISphingolipids integrate TORC2 and TORC1 through vacuolar Lo domain formation. C_LIO_LIVacuole fusion and acidification control TORC1 activity via sphingolipid metabolism. C_LI