A autophagy related-like protein 16-1 promotes the formation of autophagosomes and autolysosomes in antibacterial immune response of Pacific oyster Crassostrea gigas

Autophagy related 16-like (ATG16L) protein is a core autophagy protein, which promotes the extension of autophagosome membrane through microtubule-associated protein light chain 3 (LC3). In the present study, an ATG16L was identified from oyster Crassostrea gigas (defined as CgATG16L1). The full-length cDNA of CgATG16L1 was of 3184 bp with an open reading frame of 1650 bp that encoded a polypeptide of 549 amino acids. There was an ATG5-interacting motif (AFIM) domain, a coiled-coil (CC) domain and seven tryptophan-aspartic acid 40 (WD40) repeats in CgATG16L1. ATG16L1 mRNA was expressed in all the examined tissues with the highest expression in haemolymph (11.22-fold of that in hepatopancreas, p < 0.05). The mRNA expressions of CgATG16L1 in haemocytes increased significantly at 3, 6, 12, 24 and 72 h after lipopolysaccharide (LPS) stimulation, which were 81.15-fold, 24.95-fold, 6.02-fold, 3.90-fold and 5.97-fold (p < 0.05) of that in control group, respectively. The green positive signals of CgATG16L1 protein and the red positive signals of CgLC3 protein were dotted in the cytoplasm of agranulocytes, semi-granulocytes and granulocytes. The co-localization of CgATG16L1 and CgLC3 was observed in haemocytes after Vibrio splendidus stimulation. In CgATG16L1-RNAi oysters, the number of autophagosomes and autolysosomes in haemocytes was reduced. All these results suggested that CgATG16L1 participated in the bacteria-induced autophagy process in the haemocytes of oyster response to bacteria invasion.

Phospholipid peroxidation inhibits autophagy via stimulating the delipidation of oxidized LC3-PE

Phospholipid peroxidation of polyunsaturated fatty acids at the bis-allylic position drives ferroptosis. Here we identify a novel role for phospholipid peroxidation in the inhibition of autophagy. Using in vitro and in vivo models, we report that phospholipid peroxidation induced by glutathione peroxidase-4 inhibition and arachidonate 15-lipoxygenase overexpression leads to overload of peroxidized phospholipids and culminate in inhibition of autophagy. Functional and lipidomics analysis further demonstrated that inhibition of autophagy was associated with an increase of peroxidized phosphatidylethanolamine (PE) conjugated LC3. We further demonstrate that autophagy inhibition occurred due to preferential cleavage of peroxidized LC3-PE by ATG4B to yield delipidated LC3. Mouse models of phospholipid peroxidation and autophagy additionally supported a role for peroxidized PE in autophagy inhibition. Our results agree with the recognized role of endoplasmic reticulum as the primary source for autophagosomal membranes. In summary, our studies demonstrated that phospholipid peroxidation inhibited autophagy via stimulating the ATG4B-mediated delipidation of peroxidized LC3-PE.

[Effect of transcatheter arterial chemoembolization combined with thymosin alpha 1 on the autophagy of immune cells from advanced hepatocellular carcinoma]

Objective: To investigate the effect of transcatheter arterial chemoembolization(TACE)combined with thymosin alpha1(Tα1)on the autophagy of immune cells from advanced hepatocellular carcinoma. Methods: A total of 30 patients with advanced liver cancer enrolled in Lishui Central Hospital from September 2015 to June 2016 were collected in this study. The average age of patients was 16-75(56±12) years. All patients were treated with TACE after enrolled in hospital in a week. Patients were divided into TACE group and TACE+ Tα1 treatment group(15 cases in each group). Patients in TACE group received a conventional treatment, without any immunotherapy, while the TACE+ Tα1 treatment group accepted TACE following a subcutaneously injection of 1.6 mg Tα1 twice a week for 4 weeks. Flow cytometry was used to detect the T cell subsets in two groups both before and after TACE treatment for 1, 4 weeks and at 3 months follow-up. Peripheral blood mononuclear cells (PBMC) were isolated by density gradient centrifugation. The expression of Beclin-1, LC3 protein and mRNA were detected by Western blot (WB) and PCR respectively. Results: There was no statistical difference of the percentage of CD3(+) , CD4(+) , CD8(+) T cell subsets and Beclin-1, LC3 protein and mRNA expression between the two groups before TACE treatment (P>0.05). The percentage of CD3(+) , CD4(+) , CD8(+) T cell subsets in TACE+ Tα1 group at 1 week post-TACE treatment (58.45%±16.34%, 38.33%±15.16%, 27.31%±12.54%), at 4 weeks post-TACE treatment (62.38%±18.62%, 43.19%±13.86%, 29.54%±10.33%) and 3 months follow-up (64.15%±13.76%, 41.28%±14.65%, 29.38%±15.65%) were statistically higher than those in TACE group at 1 week post-TACE treatment (53.71%±11.17%, 32.12%±10.53%, 24.45%±13.72%) at 4 weeks post-TACE treatment (52.12%±14.26%, 31.16%±15.43%, 23.39%±15.33%) and 3 months follow-up (54.28%±13.15%, 32.17%±14.98%, 24.34%±14.12%) (P<0.05). The Beclin-1, LC3 protein and mRNA expression in TACE+ Tα1 group at 1 week post-TACE treatment (protein: 0.57±0.08, 2.26±0.36, mRNA: 0.62±0.11, 2.69±0.27), at 4 weeks post-TACE treatment (protein: 0.66±0.09, 3.11±0.45, mRNA: 0.78±0.13, 3.43±0.61) were higher than those in TACE group at 1 week post-TACE treatment (protein: 0.45±0.16, 1.43±0.30, mRNA: 0.52±0.15, 1.15±0.37), at 4 weeks post-TACE treatment (protein: 0.51±0.13, 1.81±0.35, mRNA: 0.56±0.10, 1.98±0.41) ( P<0.05). But there was no statistically significant difference in the expression of Beclin-1 and LC3 in two groups at 3 months follow-up (P>0.05). Conclusions: TACE combined with Tα1 significantly increase the level of autophagy in the immune cells of patients with advanced primary hepatocellular carcinoma.