TMEM41B is a novel regulator of autophagy and lipid mobilization

ABSTRACT: Autophagy maintains cellular homeostasis by targeting damaged organelles, pathogens or misfolded protein aggregates for lysosomal degradation. The autophagic process is initiated by the formation of autophagosomes, which can selectively enclose cargo via autophagy cargo receptors. A machinery of well-characterized autophagy-related proteins orchestrate the biogenesis of autophagosomes, however, the origin of the required membranes is incompletely understood. Here, we applied sensitized pooled CRISPR screens and identified the uncharacterized transmembrane protein TMEM41B as a novel regulator of autophagy. In the absence of TMEM41B, autophagosome biogenesis is stalled, LC3 accumulates at WIPI2- and DFCP1-positive isolation membranes, and lysosomal flux of autophagy cargo receptors and intracellular bacteria is impaired. In addition to defective autophagy, we found that TMEM41B knockout cells display significantly enlarged lipid droplets and reduced mobilization and β-oxidation of fatty acids. TMEM41B localizes to the endoplasmic reticulum (ER) and interacts with SIGMAR1, a chaperone which regulates calcium and lipid transfer at ER contact sites with mitochondria and lipid droplets. Taken together, we propose that TMEM41B is a novel regulator of autophagosome biogenesis and ER lipid mobilization.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Epithelial Cell

SUBMITTER: Debora Bonenfant  

LAB HEAD: Bonenfant Debora

PROVIDER: PXD010207 | Pride | 2018-08-20

REPOSITORIES: Pride