The human disease gene TMEM251 is essential for lysosomal transport and viral infection

ABSTRACT: After gaining access to the endo-lysosomal pathway, several viruses depend on lysosomal cathepsin proteases to cleave their structural proteins triggering productive entry. Targeting of cathepsins and other luminal lysosomal proteins to lysosomes requires their modification with mannose 6-phosphate (M6P) signals. Key to M6P tagging is N-acetylglucosamine (GlcNAc)-1-phosphotransferase whose deficiency leads to the severe lysosomal storage disorder mucolipidosis II (MLII). Here, using genome-scale CRISPR screens, we identify the transmembrane protein TMEM251 as critically important for viral infection by cathepsin-dependent viruses including reovirus, Ebola virus, and SARS-CoV-2. We demonstrate that Golgi-resident TMEM251 is essential for lysosomal sorting and activity of cathepsins. Mechanistically, we show that TMEM251 deficiency in human cells results in global loss of M6P on luminal lysosomal proteins by destabilizing GlcNAc-1-phosphotransferase. Tmem251 knockout mice reveal characteristics typical of MLII including hypersecretion of lysosomal enzymes and accumulation of lysosomal storage material in isolated fibroblasts. Finally, we demonstrate that human pathogenic TMEM251 alleles fail to rescue lysosomal sorting defects in knockout cells. Our results uncover a crucial role of TMEM251 in M6P-dependent lysosomal transport and viral infection. Overall, work here reveals the biochemical basis of an inherited MLII-like disease caused by mutations in TMEM251 and provides insights into infection mechanisms of a broad class of medically important viruses.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Nicholas Riley  

LAB HEAD: Jan Carette

PROVIDER: PXD029746 | Pride | 2022-09-09

REPOSITORIES: Pride