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As a cellular bulk degradation and survival mechanism, autophagy is implicated in diverse biological processes. Genome-wide association studies have revealed the link between autophagy gene polymorphisms and susceptibility of autoimmune diseases including systemic lupus erythematosus (SLE) and inflammatory bowel disease (IBD), indicating that autophagy dysregulation may be involved in the development of autoimmune diseases. A series of autophagy modulators have displayed protective effects on autoimmune disease models, highlighting the emerging role of autophagy modulators in treating autoimmune diseases. This review explores the roles of autophagy in the autoimmune diseases, with emphasis on four major autoimmune diseases [SLE, rheumatoid arthritis (RA), IBD, and experimental autoimmune encephalomyelitis (EAE)]. More importantly, the therapeutic potentials of small molecular autophagy modulators (including autophagy inducers and inhibitors) on autoimmune diseases are comprehensively analyzed.
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Western blotting of autophagic markers LC3Ⅱ and p62 are widely used for estimating autophagic activity. To compare the regulation of various autophagy modulators on LC3Ⅱ and p62,HEK293 cells were treated separately with mTOR-dependent autophagy activator rapamycin or -independent autophagy activators trehalose, and autophagy inhibitors including 3-methyladenine (3-MA),bafilomycin A1 or E64d and pepstatin A that inhi-bited the initiation of autophagy,the fusion of autophagosome and lysosome,and the activities of lysosomal enzymes accordingly,and then LC3Ⅱ and p62 levels were assessed. Western blot results demonstrated that rapam-ycin enhanced the conversion of LC3I to LC3Ⅱ,promoted the degradation of p62 simultaneously,while trehalose merely increased the expression of LC3Ⅱ with no influence on the p62 level. Moreover,inhibition of autophagy commonly led to accumulation of LC3Ⅱ as well as blockage of p62 degradation in a concentration- and time-dependent manner. These results indicate that obvious differences exist in the regulation of LC3Ⅱ and p62 by various modulators although both are autophagic markers.
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Objective To explore whether exendin-4 inhibits AR42J cells and its mechanism.Methods AR42J cells were treated with exendin-4 under multiple concentrations(1,5,10 pmol/L) at 24,48,72,96,120 h to assess its cell viability by MTT assay and got the IC-50 and time points.Then checking whether exendin-4 could induce the AR42Jcells apoptosis by setting normal control (NC) group,exendin-4 (Ex-4) group and Ex-4+ z-VAD-fmk (apoptosis inhibitor) group,and exploring whether 3-MA which is autophagy inhibitor could inhibit the AR42J cells apoptosis induced by exendin-4 by setting NC group,Ex-4 group and Ex-4+3-MA group.Cell viability was analyzed by MTT and the cells apoptosis was detected by flow cytometry and the protein levels of caspase-3,LC3 and p62 were studied by Western blot.Results Concentration of 10 pmol/L exendin-4 and and time point 72 h were selected for the further study.z-VAD-fmk pretreatment can significantly inhibit the cell viability of exendin-4 by (81.2±3.3)％ vs.(49.4±3.0)％ (P＜0.05).Flow cytometry showed that exendin-4 could induce the AR42J cells apoptosis by (28.2± 1.4)％ vs.(3.6±0.8)％,and increased the caspase-3 level by Western blot,which both can be reversed by (79.1 ±2.3) ％ vs.(49.8±2.5)％ (P＜0.05) when the cells were treated for 72 h,as was apoptosis ratio by (14.5±2.1)％ vs.(29.2±3.2)％.Western blot showed that exendin-4 can upregulate protein levels of LC3B-Ⅱ,p62 和 caspase-3 and 3-MA,and pretreatment can inhibit the upregulation of LC3B-Ⅱ and caspase-3 but further increased the upregulation of p62 induced by exendin-4.Conclusions Exendin-4 can induce AR42J cells apoptosis and 3-MA pretreating can inhibit exendin-4 cytotoxicity through downregulating autophagy.So auto phagy inhibitor 3-MA could potentially extenuate the cytotoxicity of exendin-4 in pancreatic acinar cells.
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Autophagy is a catabolic process responsible for the degradation and recycling of misfolded proteins and damaged organelles for cellular homeostasis. This degradative pathway,closely related to many diseases including cancer,has become a focus of cancer research. lt can serve as a tumor suppressor,also functions as a protective cell-survival mechanism against chemotherapies. Of the autophagy-related proteins,vacuolar protein sorting 34(VPS34)has attracted major attention over the past decade because of its role in autophagic procedure. Recently,three specific inhibitors of VPS34,PlK-Ⅲ,VPSlN1 and SlR405,have been invented,showing unique implications for autophagy reduction and therapeutic benefit in tumor treatment. This paper summarizes the different roles of autophagy in clinical settings and the functional regulation of VPS34 upon post-translational modification and also discusses the application prospects of inhibitors targeting VPS34 or autophagy in cancer prevention and treatment.