MOSPD3 mediates the ER recruitment of ATG2A to promote autophagy

ATG2A transfers glycerophospholipids from the endoplasmic reticulum (ER) to support expansion of the isolation membrane at ER membrane contact sites. While a role for ATG18/WIPI4 in targeting ATG2A to the IM is well established, how ATG2A is recruited to the ER remains unclear. In this study, we found that MOSPD3, an atypical VAP family protein, acts an adaptor that recruits ATG2A to the ER. MOSPD3 colocalizes with ATG2A and is specifically enriched at ER sites juxtaposed with the IM during autophagosome formation. Recruitment is mediated by direct interactions between the FFNT (two phenylalanines in a neutral tract) motif in the N-terminal region (NT) of ATG2A and the major sperm protein (MSP) domain of MOSPD3. Co-expression of MOSPD3 with ATG2A-NT, but not a MOSPD3-binding-defective mutant ATG2A-NT-T362A, markedly rescued the autophagic defect caused by ATG2A/B double knockout (DKO). MOSPD3 depletion abolishes ATG2A recruitment to the ER and impedes autophagic flux. Together, this study demonstrates that MOSPD3 functions as an ER adaptor for ATG2A in autophagy.