Project description:Within the endolysosomal pathway in mammalian cells, ESCRT complexes facilitate degradation of membrane proteins from limiting membranes of late endosomes. Recent studies revealed that yeast ESCRT proteins also sort for degradation, ubiquitinated proteins from vacuolar membrane. However, whether mammalian ESCRTs perform similar function at lysosomes remained unknown. Here, we studied the involvement of mammalian ESCRT-I in maintaining lysosomal membrane homeostasis and its implication in lysosome-related signaling. We show that ESCRT-I restricts the size of lysosomes and promotes degradation of lysosomal Ca2+ channel, MCOLN1 protein. ESCRT-I depletion induced transcriptional response related to MiT-TFE signaling and cholesterol biosynthesis, pointing to lysosomal dysfunction. The lack of ESCRT-I promoted abnormal cholesterol accumulation on lysosomes and activated TFEB/TFE3 transcription factors in Ca2+-MCOLN1-dependent, but lipid-independent manner. Hence, our study provides evidence that ESCRT-I maintains lysosomal homeostasis and elucidates MiT-TFE regulatory mechanism activated in response to ESCRT-I deprivation
Project description:Cholesterol, a key building block for cellular membranes and a precursor for steroid hormones, was recently identified as a major nutrient input that activates the master growth regulator, mammalian Target of Rapamycin Complex 1 (mTORC1) kinase. Here we identify a novel lysosomal tranmembrane protein , which we name LYsosomal CHOlesterol Signaling (LYCHOS, previously annotated as GPR155/DEPDC3), as an essential factor that enables cholesterol-dependent activation of mTORC1. RNAseq analysis of LYCHOS-depleted cells showed a pronounced dowregulation of metabolic genes involved in glycolysis, pentose phosphate pathway and lipid biosynthesis.
2022-09-01 | GSE196384 | GEO
Project description:Haploid Genetic Screen for functional cell-surface levels of CD47
