iPSCs ameliorate hypoxia-induced autophagy and atrophy in C2C12 myotubes via the AMPK/ULK1 pathway

BACKGROUND: Duchenne muscular dystrophy (DMD) is an X-linked lethal genetic disorder for which there is no effective treatment. Previous studies have shown that stem cell transplantation into mdx mice can promote muscle regeneration and improve muscle function, however, the specific molecular mechanisms remain unclear. DMD suffers varying degrees of hypoxic damage during disease progression. This study aimed to investigate whether induced pluripotent stem cells (iPSCs) have protective effects against hypoxia-induced skeletal muscle injury. RESULTS: In this study, we co-cultured iPSCs with C2C12 myoblasts using a Transwell nested system and placed them in a DG250 anaerobic workstation for oxygen deprivation for 24 h. We found that iPSCs reduced the levels of lactate dehydrogenase and reactive oxygen species and downregulated the mRNA and protein levels of BAX/BCL2 and LC3II/ LC3I in hypoxia-induced C2C12 myoblasts. Meanwhile, iPSCs decreased the mRNA and protein levels of atrogin-1 and MuRF-1 and increased myotube width. Furthermore, iPSCs downregulated the phosphorylation of AMPKA and ULK1 in C2C12 myotubes exposed to hypoxic damage. CONCLUSIONS: Our study showed that iPSCs enhanced the resistance of C2C12 myoblasts to hypoxia and inhibited apoptosis and autophagy in the presence of oxidative stress. Further, iPSCs improved hypoxia-induced autophagy and atrophy of C2C12 myotubes through the AMPK/ULK1 pathway. This study may provide a new theoretical basis for the treatment of muscular dystrophy in stem cells.

Escin alleviates chemotherapy-induced peripheral neuropathic pain by inducing autophagy in the spinal cord of rats / 南方医科大学学报

OBJECTIVE@#To investigate the effect of escin in relieving chemotherapy-induced peripheral neuropathic pain in rats and explore and the underlying mechanism.@*METHODS@#Eighteen SD rats were randomly divided into 3 groups (@*RESULTS@#The rats in both the escin preconditioning group and escin postconditioning group showed obviously increased thresholds of mechanical allodynia and thermal hyperalgesia as compared with those in the control group (@*CONCLUSIONS@#Escin can alleviate chemotherapy-induced peripheral neuropathic pain in rats possibly by upregulating the expressions of autophagy-related proteins in the spinal cord.

Effects of SP600125 on autophagy and neurocyte loss in the hippocampus of rats with subarachnoid hemorrhage / 医学研究生学报

Objective Moderate autophagy helps improve the viability of neurocytes.This study aims to investigate the effect of SP600125 on the autophagy and loss of nerve cells in the hippocampus in rats with subarachnoid hemorrhage (SHA).Methods Forty healthy male SD rats were equally randomized into a sham operation, an DMSO group, an SAH model, and an SP600125 group.The SAH model was established by vascular puncture and the rats of the SP600125 group were injected with 10 μL of SP600125 (3 μg/μL) into the lateral cerebral ventricle at 30 minutes before modeling.Sham group and SAH group were injected with equal volume of normal saline, DMSO group was injected with the same amount of DMSO.The animals were sacrificed at 24 hours after modeling for observation of the changes in the morphology and the number of neurons in the hippocampus by HE staining and qualitative and quantitative determination of the expressions of the p-JNK protein and the autophagy markers beclin-1 and LC3-II by immunohistochemistry and Western blot.Results Compared with the sham operation group, the neurons exhibited a disordered arrangement and the cells were polygonal and decreased in number in the hippocampus of the SAH models, while milder neuronal injury and more cells were observed in the rats of the SP600125 group than in the SAH models.The mean optical density values of Beclin-1, LC3-II and p-JNK in the hippocampus were significantly higher in the SAH models (14.66±4.40, 12.62±3.46, and 12.82±3.68) and DMSO (13.85±3.85、11.59±4.52、13.03±3.53), and the SP600125 group (9.86±3.14, 6.78±2.56, and 5.60±2.42) than in the sham operation group (1.56±0.28, 1.60±0.30, and 1.58±0.32) (P<0.05), but markedly lower in the SP600125 than in the SAH model group (P<0.05).The expressions of Beclin-1, LC3-II and p-JNK were remarkably increased in the SAH models (0.474±0.122, 0.668±0.130, and 0.496±0.124) and DMSO (0.432±0.102、0.628±0.113、0.416±0.094) and the SP600125 group (0.264±0.106, 0.332±0.113, and 0.219±0.104) than in the sham operation group (1.56±0.28, 1.60±0.30, and 1.58±0.32) (P<0.05), but significantly decreased in the SP600125 group as compared with the SAH models (P<0.05).Conclusion SP600125 has a protective effect on the neurocytes in the hippocampus of SAH rats, which may be associated with SP600125 moderately activating neuronal autophagy by inhibiting the activity of the JNK signaling pathway.

miR-Let7A Modulates Autophagy Induction in LPS-Activated Microglia

Microglia regulate the secretion of various immunomediators in central nervous system diseases. Microglial autophagy is the crucial process for cell's survival and cytokine productions. Recent studies have reported that several microRNAs are involved in the autophagy system. miR-Let7A is such a microRNA that plays a role in various inflammation responses, and is magnified as a key modulator particularly in the autophagy system. In present study, we investigated whether miR-Let7A is involved in autophagy in activating microglia. Overexpression of miR-Let7A in LPS-stimulated BV2 microglial cells promoted the induction of the autophagy related factors such as LC3II, Beclin1, and ATG3. Our results suggest a potential role of miR-Let7A in the autophagy process of microglia during CNS inflammation.

Cucurbitacin E induces autophagy in HeLa cells by inhibiting mTORC1 activity / 中国药理学通报

Aim To study the mechanism of cucurb-itacin E ( CuE )-induced autophagy in HeLa cells. Methods Improved MTT assay was adopted to meas-ure the effect of CuE on cell proliferation. Western blot was used to determine the phosphorylation levels of downstream signaling proteins of mTORC1 and the ex-pression of autophagy associated proteins. ResultsCuE inhibited the proliferation of HeLa cells in a dose-dependent manner, and the 24-h IC50 of CuE was 4. 01μmol· L-1 . CuE significantly inhibited the phospho-rylation of p70 S6 K in a time-and dose-dependent man-ner as evidenced by decreased phosphorylation levels of the mTORC1 substrate. Meanwhile, the expression of LC3-II, a marker for autophagosome formation, was elevated by CuE treatment, and was further increased in the presence of chloroquine. Furthermore, CuE re-duced the levels of p62/SQSTM1 . These results indi-cated that CuE induced autophagy in HeLa cells. The decreased levels of phosphorylated ULK1 S757 were posi-tively correlated with autophagy induction in HeLa cells. Conclusion CuE is likely to induce autophagy through inhibiting mTORC1 activity.

Proliferation of Toxoplasma gondii Suppresses Host Cell Autophagy

Autophagy is a process of cytoplasmic degradation of endogenous proteins and organelles. Although its primary role is protective, it can also contribute to cell death. Recently, autophagy was found to play a role in the activation of host defense against intracellular pathogens. The aims of our study was to investigate whether host cell autophagy influences Toxoplasma gondii proliferation and whether autophagy inhibitors modulate cell survival. HeLa cells were infected with T. gondii with and without rapamycin treatment to induce autophagy. Lactate dehydrogenase assays showed that cell death was extensive at 36-48 hr after infection in cells treated with T. gondii with or without rapamycin. The autophagic markers, LC3 II and Beclin 1, were strongly expressed at 18-24 hr after exposure as shown by Western blotting and RT-PCR. However, the subsequent T. gondii proliferation suppressed autophagy at 36 hr post-infection. Pre-treatment with the autophagy inhibitor, 3-methyladenine (3-MA), down-regulated LC3 II and Beclin 1. The latter was also down-regulated by calpeptin, a calpain inhibitor. Monodansyl cadaverine (MDC) staining detected numerous autophagic vacuoles (AVs) at 18 hr post-infection. Ultrastructural observations showed T. gondii proliferation in parasitophorous vacuoles (PVs) coinciding with a decline in the numbers of AVs by 18 hr. FACS analysis failed to confirm the presence of cell apoptosis after exposure to T. gondii and rapamycin. We concluded that T. gondii proliferation may inhibit host cell autophagy and has an impact on cell survival.