The lysosome, the main hub for cellular degradation and recycling processes, is emerging as a crucial signaling platform that controls cell metabolism. It is now clear that lysosomal signaling plays an important role in a variety of cancers. The Transcription Factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy, is both a substrate and a regulator of the mTORC1 lysosomal kinase complex, which drives growth and whose hyperactivation is broadly associated with cancer. Overexpression or constitutive activation of TFEB results in kidney cancer in two distinct disease entities: MiT-TFE Renal Cell Carcinoma (RCC) and Birt- Hogg-Dube' (BHD) syndrome, an inherited disease caused by mutations of folliculin (FLCN), a crucial regulator of TFEB activity. The goal of this proposal is to elucidate the mechanisms underlying TFEB-mediated kidney tumorigenesis. Emerging evidence suggest that such mechanisms may be involved in other disorders associated to kidney cancer, such Tuberous Sclerosis. Using sophisticated kidney-specific mouse transgenic models and CRE-fluorescent reporters, we will perform metabolic, biochemical, cell biology, omic and tumorigenesis assays both in vivo and in renal cultured cells with the aim of identifying the metabolic and signaling programs that underlie BHD and MiT-RCC tumorigenesis. In particular, these studies will allow us to dissect TFEB-regulated pathways that drive kidney tumorigenesis in both an mTOR- dependent and independent manner. To dissect these oncogenic programs in mechanistic depth, we will perform a detailed molecular characterization of FLCN- and mTORC1- dependent TFEB phosphorylation, coupled with candidate-based and high throughput genetic screens for novel TFEB regulators. Together, these studies will shed light on the pathogenesis of kidney tumors, and point the way toward new targets and therapeutic strategies.