PIKfyve Inhibition Controls Inflammatory Gene Expression Networks and Activates TFEB via Oxidative Stress

Lysosomes have a myriad of roles in cells. Defective lysosomes cause cellular/organismal dysfunction, including infection or neurological diseases. Lysosomal adaptation enhances lysosomal functions. One adaptation pathway, controlled by transcription factor EB (TFEB), stimulates lysosomal genes, boosting the stress resolution capacity. TFEB is controlled by mTOR and PIKfyve, however whether responses align is unclear. How PIKfyve inhibition activates TFEB is also mysterious. Here, two projects explored the PIKfyve-TFEB pathway. First, using transcriptomics, qRT-PCR, and Western blots in wild-type and macrophages lacking TFEB/TFE3, PIKfyve and mTOR inhibition caused differential gene expression that was mostly TFEB-dependent. PIKfyve inhibition, possibly through TFEB, may promote anti-inflammation, increasing ATF3 and decreasing FOS and IL6RA. Second, fluorescent imaging showed PIKfyve inhibition disrupts mitochondrial dynamics and promotes ROS production, driving ROS-dependent TFEB activation. PIKfyve associated diseases are often assumed to be endo-lysosomal trafficking related, but our work suggests they may depend on gene expression changes and mitochondrial disruptions.