ATG16L1 induces the formation of phagophore-like membrane cups.

The hallmark of non-selective autophagy is the formation of cup-shaped phagophores that capture bulk cytoplasm. The process is accompanied by the conjugation of LC3B to phagophores by an E3 ligase complex comprising ATG12-ATG5 and ATG16L1. Here we combined two complementary reconstitution approaches to reveal the function of LC3B and its ligase complex during phagophore expansion. We found that LC3B forms together with ATG12-ATG5-ATG16L1 a membrane coat that remodels flat membranes into cups that closely resemble phagophores. Mechanistically, we revealed that cup formation strictly depends on a close collaboration between LC3B and ATG16L1. Moreover, only LC3B, but no other member of the ATG8 protein family, promotes cup formation. ATG16L1 truncates that lacked the C-terminal membrane binding domain catalyzed LC3B lipidation but failed to assemble coats, did not promote cup formation and inhibited the biogenesis of non-selective autophagosomes. Our results thus demonstrate that ATG16L1 and LC3B induce and stabilize the characteristic cup-like shape of phagophores.

TECPR1 promotes aggrephagy by direct recruitment of LC3C autophagosomes to lysosomes.

The accumulation of protein aggregates is involved in the onset of many neurodegenerative diseases. Aggrephagy is a selective type of autophagy that counteracts neurodegeneration by degrading such aggregates. In this study, we found that LC3C cooperates with lysosomal TECPR1 to promote the degradation of disease-related protein aggregates in neural stem cells. The N-terminal WD-repeat domain of TECPR1 selectively binds LC3C which decorates matured autophagosomes. The interaction of LC3C and TECPR1 promotes the recruitment of autophagosomes to lysosomes for degradation. Augmented expression of TECPR1 in neural stem cells reduces the number of protein aggregates by promoting their autophagic clearance, whereas knockdown of LC3C inhibits aggrephagy. The PH domain of TECPR1 selectively interacts with PtdIns(4)P to target TECPR1 to PtdIns(4)P containing lysosomes. Exchanging the PH against a tandem-FYVE domain targets TECPR1 ectopically to endosomes. This leads to an accumulation of LC3C autophagosomes at endosomes and prevents their delivery to lysosomes.

Protective effect of shrimp carotenoids against ammonia stress in common carp, Cyprinus carpio.

This study is aimed at evaluating the protective effect of shrimp carotenoids on ammonia stress in common carp. Crude carotenoid extract from shrimp exoskeleton, astaxanthin and astaxanthin ester fractionated from crude extract was fed to the common carp fingerlings at 100 and 200ppm concentration by incorporating carotenoids into feed. Experimental and control fish were then exposed to sublethal dose of ammonia. Serum total antioxidant status (TAS), activities of superoxide dismutase (SOD) and catalase were measured to determine the effect of dietary carotenoid on defense status of fish. Activities of aspartate transaminase (AST) and alanine transaminase (ALT) were measured to determine the protective effect of carotenoids against tissue damage caused by the ammonia stress. TAS, catalase and SOD activity was higher in tissues from fish fed with the diet containing astaxanthin rich and astaxanthin ester rich extract compared to fish fed with control diet. TAS reduced in the tissues considerably after exposure to ammonia. However, TAS was still higher in tissues from fish fed with carotenoid containing diet than in tissues from fish fed with control diet. Eventhough there was an increase in the activities of ALT and AST due to stress by ammonia toxicity in all groups, fish fed with astaxanthin extract had lower activities and also prevented lipid peroxidation in the tissues. In conclusion, shrimp carotenoid increased the resistance of common carp fingerlings to ammonia induced stress.