The goal of this project is to gain a deeper knowledge on the mechanisms that regulate the lysosome in an effort to identify novel tools to regulate its function. This knowledge could have a direct impact on the development of therapeutic options for lysosomal storage diseases (LSDs), a group of over 50 inherited diseases with a progressive and multisystemic phenotype, which mostly affect children. In 2009 we discovered that lysosomal function and autophagy are subject to a global transcriptional regulation, which is mediated by the master gene TFEB (Sardiello et al. Science 2009; Settembre et al. Science, 2011). This regulatory pathway allows the lysosome to respond to environmental cues such as starvation, physical exercise, infection, and a variety of stress conditions. TFEB mediates a lysosome-to-nucleus signaling mechanism that originates from the lysosomal surface and is regulated by the mTORC1 kinase. Induction lysosomal biogenesis and autophagy via TFEB has proven to be a potent tool to promote cellular clearance in LSDs and neurodegenerative diseases (Medina et al, Dev Cell,2011, Decressac et al, PNAS, 2013). In spite of these exciting developments several knowledge gaps remain in our understanding of how TFEB is regulated at both transcriptional and post-translational levels and on how we could be modulate lysosomal function and cellular clearance to treat human diseases. This project aims at tackling these gaps by: 1) dissecting the molecular and developmental cues responsible for TFEB transcriptional regulation and on the definition of TFEB epigenetic landscape in steady-state conditions; 2) identifying the pathways that mediate TFEB nuclear export and the players involved. A deeper understanding of these pathways may lead to the identification of tools (and potential targets) to either inhibit or enhance TFEB nuclear export and 3) studying pathways alternative to TFEB that regulate lysosomal function in an effort to identify novel signalling pathways and molecules that regulate, either directly or indirectly, lysosomal function. The results of these studies will be instrumental in identifying new strategies and tools to safely and effectively modulate clearance of lysosomal storage in a variety of diseases.