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Sample records for autophagy genes protect

  1. Autophagy Gene Variant IRGM −261T Contributes to Protection from Tuberculosis Caused by Mycobacterium tuberculosis but Not by M. africanum Strains

    PubMed Central

    Browne, Edmund N. L.; Amanua Chinbuah, Margaret; Enimil, Anthony; Gyapong, John; Osei, Ivy; Owusu-Dabo, Ellis; Helm, Susanne; Rüsch-Gerdes, Sabine; Horstmann, Rolf D.; Meyer, Christian G.

    2009-01-01

    The human immunity-related GTPase M (IRGM) has been shown to be critically involved in regulating autophagy as a means of disposing cytosolic cellular structures and of reducing the growth of intracellular pathogens in vitro. This includes Mycobacterium tuberculosis, which is in agreement with findings indicating that M. tuberculosis translocates from the phagolysosome into the cytosol of infected cells, where it becomes exposed to autophagy. To test whether IRGM plays a role in human infection, we studied IRGM gene variants in 2010 patients with pulmonary tuberculosis (TB) and 2346 unaffected controls. Mycobacterial clades were classified by spoligotyping, IS6110 fingerprinting and genotyping of the pks1/15 deletion. The IRGM genotype −261TT was negatively associated with TB caused by M. tuberculosis (OR 0.66, CI 0.52–0.84, Pnominal 0.0009, Pcorrected 0.0045) and not with TB caused by M. africanum or M. bovis (OR 0.95, CI 0.70–1.30. P 0.8). Further stratification for mycobacterial clades revealed that the protective effect applied only to M. tuberculosis strains with a damaged pks1/15 gene which is characteristic for the Euro-American (EUAM) subgroup of M. tuberculosis (OR 0.63, CI 0.49–0.81, Pnominal 0.0004, Pcorrected 0.0019). Our results, including those of luciferase reporter gene assays with the IRGM variants −261C and −261T, suggest a role for IRGM and autophagy in protection of humans against natural infection with M. tuberculosis EUAM clades. Moreover, they support in vitro findings indicating that TB lineages capable of producing a distinct mycobacterial phenolic glycolipid that occurs exclusively in strains with an intact pks1/15 gene inhibit innate immune responses in which IRGM contributes to the control of autophagy. Finally, they raise the possibility that the increased frequency of the IRGM −261TT genotype may have contributed to the establishment of M. africanum as a pathogen in the West African population. PMID:19750224

  2. Flavivirus NS4A-induced autophagy protects cells against death and enhances virus replication.

    PubMed

    McLean, Jeffrey E; Wudzinska, Aleksandra; Datan, Emmanuel; Quaglino, Daniela; Zakeri, Zahra

    2011-06-24

    Flaviviruses include the most prevalent and medically challenging viruses. Persistent infection with flaviviruses of epithelial cells and hepatocytes that do not undergo cell death is common. Here, we report that, in epithelial cells, up-regulation of autophagy following flavivirus infection markedly enhances virus replication and that one flavivirus gene, NS4A, uniquely determines the up-regulation of autophagy. Dengue-2 and Modoc (a murine flavivirus) kill primary murine macrophages but protect epithelial cells and fibroblasts against death provoked by several insults. The flavivirus-induced protection derives from the up-regulation of autophagy, as up-regulation of autophagy by starvation or inactivation of mammalian target of rapamycin also protects the cells against insult, whereas inhibition of autophagy via inactivation of PI3K nullifies the protection conferred by flavivirus. Inhibition of autophagy also limits replication of both Dengue-2 and Modoc virus in epithelial cells. Expression of flavivirus NS4A is sufficient to induce PI3K-dependent autophagy and to protect cells against death; expression of other viral genes, including NS2A and NS4B, fails to protect cells against several stressors. Flavivirus NS4A protein induces autophagy in epithelial cells and thus protects them from death during infection. As autophagy is vital to flavivirus replication in these cells, NS4A is therefore also identified as a critical determinant of flavivirus replication. PMID:21511946

  3. Punicalagin promotes autophagy to protect primary human syncytiotrophoblasts from apoptosis.

    PubMed

    Wang, Ying; Chen, Baosheng; Longtine, Mark S; Nelson, D Michael

    2016-02-01

    Punicalagin is a prominent polyphenol in pomegranate juice that protects cultured syncytiotrophoblasts from stress-induced apoptosis. Here, we test the hypothesis that punicalagin has this effect by inhibiting the mTOR kinase pathway to enhance autophagic turnover and limit apoptosis in cultured primary human syncytiotrophoblasts. In syncytiotrophoblasts, starvation, rapamycin, or punicalagin all decreased the expression of phosphorylated ribosomal protein S6, a downstream target of the mTOR kinase, and of the autophagy markers, LC3-II and p62. In contrast, in the presence of bafilomycin, an inhibitor of late stages of autophagy and degradation in the autophagolysosome, syncytiotrophoblasts exposed to starvation, rapamycin, or punicalagin all showed increased levels of LC3-II and p62. The number of LC3-II punctae also increased in punicalagin-treated syncytiotrophoblasts exposed to chloroquine, another inhibitor of autophagic degradation, and punicalagin increased the number of lysosomes. The apoptosis-reducing effect of punicalagin was attenuated by inhibition of autophagy using bafilomycin or knockdown of the autophagy related gene, ATG16L1. Collectively, these data support the hypothesis that punicalagin modulates the crosstalk between autophagy and apoptosis to promote survival in cultured syncytiotrophoblasts. PMID:26659860

  4. FoxO3a Directs a Protective Autophagy Program in Hematopoietic Stem Cells

    PubMed Central

    Warr, Matthew R.; Binnewies, Mikhail; Flach, Johanna; Reynaud, Damien; Garg, Trit; Malhotra, Ritu; Debnath, Jayanta; Passegué, Emmanuelle

    2013-01-01

    Blood production is ensured by rare self-renewing hematopoietic stem cells (HSCs). How HSCs accommodate the diverse cellular stresses associated with their life-long activity remains elusive. Here, we identify autophagy as an essential mechanism protecting HSCs from metabolic stress. We show that HSCs, in contrast to their short-lived myeloid progeny, robustly induce autophagy following ex vivo cytokine withdrawal and in vivo caloric restriction. We demonstrate that FoxO3a is critical to maintain a gene expression program that poise HSCs for rapid induction of autophagy upon starvation. Notably, we find that old HSCs retain an intact FoxO3a-driven pro-autophagy gene program, and that ongoing autophagy is needed to mitigate an energy crisis and allow their survival. Our results demonstrate that autophagy is essential for the life-long maintenance of the HSC compartment and for supporting an old, failing blood system. PMID:23389440

  5. Autophagy

    PubMed Central

    Hale, Amber N.; Ledbetter, Dan J.; Gawriluk, Thomas R.; Rucker, III, Edmund B.

    2013-01-01

    Autophagy is an evolutionarily conserved cellular process through which long-lived proteins and damaged organelles are recycled to maintain energy homeostasis. These proteins and organelles are sequestered into a double-membrane structure, or autophagosome, which subsequently fuses with a lysosome in order to degrade the cargo. Although originally classified as a type of programmed cell death, autophagy is more widely viewed as a basic cell survival mechanism to combat environmental stressors. Autophagy genes were initially identified in yeast and were found to be necessary to circumvent nutrient stress and starvation. Subsequent elucidation of mammalian gene counterparts has highlighted the importance of this process to normal development. This review provides an overview of autophagy, the types of autophagy, its regulation and its known impact on development gleaned primarily from murine models. PMID:24121596

  6. Autophagy is activated to protect against endotoxic acute kidney injury.

    PubMed

    Mei, Shuqin; Livingston, Man; Hao, Jielu; Li, Lin; Mei, Changlin; Dong, Zheng

    2016-01-01

    Endotoxemia in sepsis, characterized by systemic inflammation, is a major cause of acute kidney injury (AKI) in hospitalized patients, especially in intensive care unit; however the underlying pathogenesis is poorly understood. Autophagy is a conserved, cellular catabolic pathway that plays crucial roles in cellular homeostasis including the maintenance of cellular function and viability. The regulation and role of autophagy in septic or endotoxic AKI remains unclear. Here we show that autophagy was induced in kidney tubular cells in mice by the endotoxin lipopolysaccharide (LPS). Pharmacological inhibition of autophagy with chloroquine enhanced LPS-induced AKI. Moreover, specific ablation of autophagy gene 7 (Atg7) from kidney proximal tubules worsened LPS-induced AKI. Together, the results demonstrate convincing evidence of autophagy activation in endotoxic kidney injury and support a renoprotective role of autophagy in kidney tubules. PMID:26916346

  7. Autophagy protects intestinal epithelial cells against deoxynivalenol toxicity by alleviating oxidative stress via IKK signaling pathway.

    PubMed

    Tang, Yulong; Li, Jianjun; Li, Fengna; Hu, Chien-An A; Liao, Peng; Tan, Kunrong; Tan, Bie; Xiong, Xia; Liu, Gang; Li, Tiejun; Yin, Yulong

    2015-12-01

    Autophagy is an intracellular process of homeostatic degradation that promotes cell survival under various stressors. Deoxynivalenol (DON), a fungal toxin, often causes diarrhea and disturbs the homeostasis of the intestinal system. To investigate the function of intestinal autophagy in response to DON and associated mechanisms, we firstly knocked out ATG5 (autophagy-related gene 5) in porcine intestinal epithelial cells (IPEC-J2) using CRISPR-Cas9 technology. When treated with DON, autophagy was induced in IPEC-J2 cells but not in IPEC-J2.Atg5ko cells. The deficiency in autophagy increased DON-induced apoptosis in IPEC-J2.atg5ko cells, in part, through the generation of reactive oxygen species (ROS). The cellular stress response can be restored in IPEC-J2.atg5ko cells by overexpressing proteins involved in protein folding. Interestingly, we found that autophagy deficiency downregulated the expression of endoplasmic reticulum folding proteins BiP and PDI when IPEC-J2.atg5ko cells were treated with DON. In addition, we investigated the molecular mechanism of autophagy involved in the IKK, AMPK, and mTOR signaling pathway and found that Bay-117082 and Compound C, specific inhibitors for IKK and AMPK, respectively, inhibited the induction of autophagy. Taken together, our results suggest that autophagy is pivotal for protection against DON in pig intestinal cells. PMID:26456059

  8. Overexpression of Annexin II Receptor-Induced Autophagy Protects Against Apoptosis in Uveal Melanoma Cells.

    PubMed

    Zhang, Yuelu; Song, Hongyuan; Guo, Ting; Zhu, Yongzhe; Tang, Hailin; Qi, Zhongtian; Zhao, Ping; Zhao, Shihong

    2016-05-01

    Uveal melanoma is the most common primary malignant intraocular tumor in adults and still lacks effective systemic therapies. Annexin A2 receptor (AXIIR), a receptor for Annexin II, was demonstrated to play an important role in multiple cells, but its role in uveal melanoma cells remains exclusive. Herein, the authors reported that overexpression of AXIIR was able to reduce cell viability and activate apoptosis apparently in the Mum2C uveal melanoma cell line. Meanwhile, overexpression of AXIIR could induce autophagy and increase autophagy flux. After autophagy was inhibited by chloroquine, enhanced apoptosis and cytotoxicity could be detected. In summary, these data highlighted the crucial role of AXIIR in reducing Mum2C cell viability through inducing apoptosis, while autophagy played a protective role in this process. Interference of this gene may be a promising method for uveal melanoma therapy and combination with specific inhibitor of autophagy may serve as a supplementary. PMID:27183438

  9. Autophagy protects C. elegans against necrosis during Pseudomonas aeruginosa infection

    PubMed Central

    Zou, Cheng-Gang; Ma, Yi-Cheng; Dai, Li-Li; Zhang, Ke-Qin

    2014-01-01

    Autophagy, a conserved pathway that delivers intracellular materials into lysosomes for degradation, is involved in development, aging, and a variety of diseases. Accumulating evidence demonstrates that autophagy plays a protective role against infectious diseases by diminishing intracellular pathogens, including bacteria, viruses, and parasites. However, the mechanism by which autophagy regulates innate immunity remains largely unknown. Here, we show that autophagy is involved in host defense against a pathogenic bacterium Pseudomonas aeruginosa in the metazoan Caenorhabditis elegans. P. aeruginosa infection induces autophagy via a conserved extracellular signal-regulated kinase (ERK). Intriguingly, impairment of autophagy does not influence the intestinal accumulation of P. aeruginosa, but instead induces intestinal necrosis. Inhibition of necrosis results in the survival of autophagy-deficient worms after P. aeruginosa infection. These findings reveal a previously unidentified role for autophagy in protection against necrosis triggered by pathogenic bacteria in C. elegans and implicate that such a function of autophagy may be conserved through the inflammatory response in diverse organisms. PMID:25114220

  10. The Cannabinoid Receptor 2 Protects Against Alcoholic Liver Disease Via a Macrophage Autophagy-Dependent Pathway.

    PubMed

    Denaës, Timothé; Lodder, Jasper; Chobert, Marie-Noële; Ruiz, Isaac; Pawlotsky, Jean-Michel; Lotersztajn, Sophie; Teixeira-Clerc, Fatima

    2016-01-01

    Kupffer cells, the resident macrophages of the liver, play a major role in the pathogenesis of alcoholic liver disease. We have previously demonstrated that CB2 receptor protects against alcoholic liver disease by inhibiting alcohol-induced inflammation and steatosis via the regulation of Kupffer cell activation. Here, we explored the mechanism underlying these effects and hypothesized that the anti-inflammatory properties of CB2 receptor in Kupffer cells rely on activation of autophagy. For this purpose, mice invalidated for CB2 receptor (CB2(Mye-/-) mice) or for the autophagy gene ATG5 (ATG5(Mye-/-) mice) in the myeloid lineage, and their littermate wild-type mice were subjected to chronic-plus-binge ethanol feeding. CB2(Mye-/-) mice showed exacerbated alcohol-induced pro-inflammatory gene expression and steatosis. Studies in cultured macrophages demonstrated that CB2 receptor activation by JWH-133 stimulated autophagy via a heme oxygenase-1 dependent pathway. Moreover, JWH-133 reduced the induction of inflammatory genes by lipopolysaccharide in wild-type macrophages, but not in ATG5-deficient cells. The CB2 agonist also protected from alcohol-induced liver inflammation and steatosis in wild-type mice, but not in ATG5(Mye-/-) mice demonstrating that macrophage autophagy mediates the anti-inflammatory and anti-steatogenic effects of CB2 receptor. Altogether these results demonstrate that CB2 receptor activation in macrophages protects from alcohol-induced steatosis by inhibiting hepatic inflammation through an autophagy-dependent pathway. PMID:27346657

  11. E2F1 regulates autophagy and the transcription of autophagy genes.

    PubMed

    Polager, S; Ofir, M; Ginsberg, D

    2008-08-14

    The retinoblastoma pathway is often inactivated in human tumors resulting in deregulated E2F activity that can induce both proliferation and cell death. Although the role of E2F in apoptosis is well characterized, little is known regarding its putative participation in other cell death pathways. We show here that activation of E2F1 upregulates the expression of four autophagy genes-microtubule-associated protein-1 light chain-3 (LC3), autophagy-related gene-1 (ATG1), ATG5 and damage-regulated autophagy modulator (DRAM). E2F1-mediated induction of LC3, ATG1 and DRAM is direct and indeed, endogenous E2F1 can be found bound to regions encompassing the promoters of these genes. Regulation of ATG5 by E2F1 is indirect. Importantly, we demonstrate that E2F1 activation enhances autophagy and conversely, reducing endogenous E2F1 expression inhibits DNA damage-induced autophagy. These studies identify E2F1 as a transcriptional regulator of autophagy, and for the first time establish a role for E2F1 in DNA damage-induced autophagy. PMID:18408756

  12. 6-Gingerol induces autophagy to protect HUVECs survival from apoptosis.

    PubMed

    Wang, Shaopeng; Sun, Xiance; Jiang, Liping; Liu, Xiaofang; Chen, Min; Yao, Xiaofeng; Sun, Qinghua; Yang, Guang

    2016-08-25

    6-Gingerol, the major pharmacologically-active component of ginger, has the potential to prevent heart disease. However, the mechanisms are not well understood. In this study, the protective effect of 6-gingerol against hydrogen peroxide-induced apoptosis in human umbilical vein endothelial cells (HUVECs) was investigated. Apoptosis was detected by Hoechst 33342 and Flow cytometry analysis. To further elucidate the crosstalk between apoptosis and autophagy, we tested the expression of autophagy related proteins, LC3B, Bcl-2, Beclin1, AKT, p-AKT, mechanistic target of rapamycin (mTOR), and p-mTOR. Furthermore, mitochondrial membrane potential and the intracellular generation of reactive oxygen species (ROS) were also investigated. Our data revealed that 6-gingerol significantly reduced apoptosis by inducing autophagy. It has been demonstrated that 6-gingerol suppressed the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling pathway, increased the expression of Beclin1 to promote autophagy, and increased Bcl-2 expression to inhibit apoptosis. In addition, the damage of mitochondrial was protected, and ROS level was decreased by 6-gingerol. These firmly indicate 6-gingerol has a strong protective ability against the apoptosis caused by oxidative stress in HUVECs, and the mechanism may relate to the induction of autophagy. Our data suggest 6-gingerol may be beneficial in the prevention of atherosclerosis. PMID:27451028

  13. Calpain inhibition mediates autophagy-dependent protection against polyglutamine toxicity

    PubMed Central

    Menzies, F M; Garcia-Arencibia, M; Imarisio, S; O'Sullivan, N C; Ricketts, T; Kent, B A; Rao, M V; Lam, W; Green-Thompson, Z W; Nixon, R A; Saksida, L M; Bussey, T J; O'Kane, C J; Rubinsztein, D C

    2015-01-01

    Over recent years, accumulated evidence suggests that autophagy induction is protective in animal models of a number of neurodegenerative diseases. Intense research in the field has elucidated different pathways through which autophagy can be upregulated and it is important to establish how modulation of these pathways impacts upon disease progression in vivo and therefore which, if any, may have further therapeutic relevance. In addition, it is important to understand how alterations in these target pathways may affect normal physiology when constitutively modulated over a long time period, as would be required for treatment of neurodegenerative diseases. Here we evaluate the potential protective effect of downregulation of calpains. We demonstrate, in Drosophila, that calpain knockdown protects against the aggregation and toxicity of proteins, like mutant huntingtin, in an autophagy-dependent fashion. Furthermore, we demonstrate that, overexpression of the calpain inhibitor, calpastatin, increases autophagosome levels and is protective in a mouse model of Huntington's disease, improving motor signs and delaying the onset of tremors. Importantly, long-term inhibition of calpains did not result in any overt deleterious phenotypes in mice. Thus, calpain inhibition, or activation of autophagy pathways downstream of calpains, may be suitable therapeutic targets for diseases like Huntington's disease. PMID:25257175

  14. Characterization of a novel autophagy-specific gene, ATG29

    SciTech Connect

    Kawamata, Tomoko; Kamada, Yoshiaki; Suzuki, Kuninori; Kuboshima, Norihiro; Akimatsu, Hiroshi; Ota, Shinichi; Ohsumi, Mariko; Ohsumi, Yoshinori . E-mail: yohsumi@nibb.ac.jp

    2005-12-30

    Autophagy is a process whereby cytoplasmic proteins and organelles are sequestered for bulk degradation in the vacuole/lysosome. At present, 16 ATG genes have been found that are essential for autophagosome formation in the yeast Saccharomyces cerevisiae. Most of these genes are also involved in the cytoplasm to vacuole transport pathway, which shares machinery with autophagy. Most Atg proteins are colocalized at the pre-autophagosomal structure (PAS), from which the autophagosome is thought to originate, but the precise mechanism of autophagy remains poorly understood. During a genetic screen aimed to obtain novel gene(s) required for autophagy, we identified a novel ORF, ATG29/YPL166w. atg29{delta} cells were sensitive to starvation and induction of autophagy was severely retarded. However, the Cvt pathway operated normally. Therefore, ATG29 is an ATG gene specifically required for autophagy. Additionally, an Atg29-GFP fusion protein was observed to localize to the PAS. From these results, we propose that Atg29 functions in autophagosome formation at the PAS in collaboration with other Atg proteins.

  15. Analysis of Autophagy Genes in Microalgae: Chlorella as a Potential Model to Study Mechanism of Autophagy

    PubMed Central

    Jiang, Qiao; Zhao, Li; Dai, Junbiao; Wu, Qingyu

    2012-01-01

    Background Microalgae, with the ability to mitigate CO2 emission and produce carbohydrates and lipids, are considered one of the most promising resources for producing bioenergy. Recently, we discovered that autophagy plays a critical role in the metabolism of photosynthetic system and lipids production. So far, more than 30-autophagy related (ATG) genes in all subtypes of autophagy have been identified. However, compared with yeast and mammals, in silico and experimental research of autophagy pathways in microalgae remained limited and fragmentary. Principal Findings In this article, we performed a genome-wide analysis of ATG genes in 7 microalgae species and explored their distributions, domain structures and evolution. Eighteen “core autophagy machinery” proteins, four mammalian-specific ATG proteins and more than 30 additional proteins (including “receptor-adaptor” complexes) in all subtypes of autophagy were analyzed. Data revealed that receptor proteins in cytoplasm-to-vacuole targeting and mitophagy seem to be absent in microalgae. However, most of the “core autophagy machinery” and mammalian-specific proteins are conserved among microalgae, except for the ATG9-cycling system in Chlamydomonas reinhardtii and the second ubiquitin-like protein conjugation complex in several algal species. The catalytic and binding residues in ATG3, ATG5, ATG7, ATG8, ATG10 and ATG12 are also conserved and the phylogenetic tree of ATG8 coincides well with the phylogenies. Chlorella contains the entire set of the core autophagy machinery. In addition, RT-PCR analysis verified that all crucial ATG genes tested are expressed during autophagy in both Chlorella and Chlamydomonas reinhardtii. Finally, we discovered that addition of 3-Methyladenine (a PI3K specific inhibitor) could suppress the formation of autophagic vacuoles in Chlorella. Conclusions Taken together, Chlorella may represent a potential model organism to investigate autophagy pathways in photosynthetic

  16. The Cannabinoid Receptor 2 Protects Against Alcoholic Liver Disease Via a Macrophage Autophagy-Dependent Pathway

    PubMed Central

    Denaës, Timothé; Lodder, Jasper; Chobert, Marie-Noële; Ruiz, Isaac; Pawlotsky, Jean-Michel; Lotersztajn, Sophie; Teixeira-Clerc, Fatima

    2016-01-01

    Kupffer cells, the resident macrophages of the liver, play a major role in the pathogenesis of alcoholic liver disease. We have previously demonstrated that CB2 receptor protects against alcoholic liver disease by inhibiting alcohol-induced inflammation and steatosis via the regulation of Kupffer cell activation. Here, we explored the mechanism underlying these effects and hypothesized that the anti-inflammatory properties of CB2 receptor in Kupffer cells rely on activation of autophagy. For this purpose, mice invalidated for CB2 receptor (CB2Mye−/− mice) or for the autophagy gene ATG5 (ATG5Mye−/− mice) in the myeloid lineage, and their littermate wild-type mice were subjected to chronic-plus-binge ethanol feeding. CB2Mye−/− mice showed exacerbated alcohol-induced pro-inflammatory gene expression and steatosis. Studies in cultured macrophages demonstrated that CB2 receptor activation by JWH-133 stimulated autophagy via a heme oxygenase-1 dependent pathway. Moreover, JWH-133 reduced the induction of inflammatory genes by lipopolysaccharide in wild-type macrophages, but not in ATG5-deficient cells. The CB2 agonist also protected from alcohol-induced liver inflammation and steatosis in wild-type mice, but not in ATG5Mye−/− mice demonstrating that macrophage autophagy mediates the anti-inflammatory and anti-steatogenic effects of CB2 receptor. Altogether these results demonstrate that CB2 receptor activation in macrophages protects from alcohol-induced steatosis by inhibiting hepatic inflammation through an autophagy-dependent pathway. PMID:27346657

  17. Inhibition of glycogen synthase kinase 3β promotes autophagy to protect mice from acute liver failure mediated by peroxisome proliferator-activated receptor α

    PubMed Central

    Ren, F; Zhang, L; Zhang, X; Shi, H; Wen, T; Bai, L; Zheng, S; Chen, Y; Chen, D; Li, L; Duan, Z

    2016-01-01

    Our previous studies have demonstrated that inhibition of glycogen synthase kinase 3β (GSK3β) activity protects mice from acute liver failure (ALF), whereas its protective and regulatory mechanism remains elusive. Autophagy is a recently recognized rudimentary cellular response to inflammation and injury. The aim of the present study was to test the hypothesis that inhibition of GSK3β mediates autophagy to inhibit liver inflammation and protect against ALF. In ALF mice model induced by d-galactosamine (d-GalN) and lipopolysaccharide (LPS), autophagy was repressed compared with normal control, and d-GalN/LPS can directly induce autophagic flux in the progression of ALF mice. Autophagy activation by rapamycin protected against liver injury and its inhibition by 3-methyladenine (3-MA) or autophagy gene 7 (Atg7) small interfering RNA (siRNA) exacerbated liver injury. The protective effect of GSK3β inhibition on ALF mice model depending on the induction of autophagy, because that inhibition of GSK3β promoted autophagy in vitro and in vivo, and inhibition of autophagy reversed liver protection and inflammation of GSK3β inhibition. Furthermore, inhibition of GSK3β increased the expression of peroxisome proliferator-activated receptor α (PPARα), and the downregulated PPARα by siRNA decreased autophagy induced by GSK3β inhibition. More importantly, the expressions of autophagy-related gene and PPARα are significantly downregulated and the activity of GSK3β is significantly upregulated in liver of ALF patients with hepatitis B virus. Thus, we have demonstrated the new pathological mechanism of ALF that the increased GSK3β activity suppresses autophagy to promote the occurrence and development of ALF by inhibiting PPARα pathway. PMID:27010852

  18. Autophagy protects ovarian cancer-associated fibroblasts against oxidative stress

    PubMed Central

    Wang, Qian; Xue, Liang; Zhang, Xiaoyu; Bu, Shixia; Zhu, Xueliang; Lai, Dongmei

    2016-01-01

    ABSTRACT RNA-Seq and gene set enrichment anylysis revealed that ovarian cancer associated fibroblasts (CAFs) are mitotically active compared with normal fibroblasts (NFs). Cellular senescence is observed in CAFs treated with H2O2 as shown by elevated SA-β-gal activity and p21 (WAF1/Cip1) protein levels. Reactive oxygen species (ROS) production and p21 (WAF1/Cip1) elevation may account for H2O2-induced CAFs cell cycle arrest in S phase. Blockage of autophagy can increase ROS production in CAFs, leading to cell cycle arrest in S phase, cell proliferation inhibition and enhanced sensitivity to H2O2-induced cell death. ROS scavenger NAC can reduce ROS production and thus restore cell viability. Lactate dehydrogenase A (LDHA), monocarboxylic acid transporter 4 (MCT4) and superoxide dismutase 2 (SOD2) were up-regulated in CAFs compared with NFs. There was relatively high lactate content in CAFs than in NFs. Blockage of autophagy decreased LDHA, MCT4 and SOD2 protein levels in CAFs that might enhance ROS production. Blockage of autophagy can sensitize CAFs to chemotherapeutic drug cisplatin, implicating that autophagy might possess clinical utility as an attractive target for ovarian cancer treatment in the future. PMID:27074587

  19. Autophagy protects ovarian cancer-associated fibroblasts against oxidative stress.

    PubMed

    Wang, Qian; Xue, Liang; Zhang, Xiaoyu; Bu, Shixia; Zhu, Xueliang; Lai, Dongmei

    2016-05-18

    RNA-Seq and gene set enrichment anylysis revealed that ovarian cancer associated fibroblasts (CAFs) are mitotically active compared with normal fibroblasts (NFs). Cellular senescence is observed in CAFs treated with H2O2 as shown by elevated SA-β-gal activity and p21 (WAF1/Cip1) protein levels. Reactive oxygen species (ROS) production and p21 (WAF1/Cip1) elevation may account for H2O2-induced CAFs cell cycle arrest in S phase. Blockage of autophagy can increase ROS production in CAFs, leading to cell cycle arrest in S phase, cell proliferation inhibition and enhanced sensitivity to H2O2-induced cell death. ROS scavenger NAC can reduce ROS production and thus restore cell viability. Lactate dehydrogenase A (LDHA), monocarboxylic acid transporter 4 (MCT4) and superoxide dismutase 2 (SOD2) were up-regulated in CAFs compared with NFs. There was relatively high lactate content in CAFs than in NFs. Blockage of autophagy decreased LDHA, MCT4 and SOD2 protein levels in CAFs that might enhance ROS production. Blockage of autophagy can sensitize CAFs to chemotherapeutic drug cisplatin, implicating that autophagy might possess clinical utility as an attractive target for ovarian cancer treatment in the future. PMID:27074587

  20. Polymorphisms in Autophagy Genes and Susceptibility to Tuberculosis

    PubMed Central

    Alisjahbana, Bachti; Sahiratmadja, Edhyana; Parwati, Ida; Oosting, Marije; Plantinga, Theo S.; Joosten, Leo A. B.; Netea, Mihai G.; Ottenhoff, Tom H. M.; van de Vosse, Esther; van Crevel, Reinout

    2012-01-01

    Recent data suggest that autophagy is important for intracellular killing of Mycobacterium tuberculosis, and polymorphisms in the autophagy gene IRGM have been linked with susceptibility to tuberculosis (TB) among African-Americans, and with TB caused by particular M. tuberculosis genotypes in Ghana. We compared 22 polymorphisms of 14 autophagy genes between 1022 Indonesian TB patients and 952 matched controls, and between patients infected with different M. tuberculosis genotypes, as determined by spoligotyping. The same autophagy polymorphisms were studied in correlation with ex-vivo production of TNF, IL-1β, IL-6, IL-8, IFN-γ and IL-17 in healthy volunteers. No association was found between TB and polymorphisms in the genes ATG10, ATG16L2, ATG2B, ATG5, ATG9B, IRGM, LAMP1, LAMP3, P2RX7, WIPI1, MTOR and ATG4C. Associations were found between polymorphisms in LAMP1 (p = 0.02) and MTOR (p = 0.02) and infection with the successful M. tuberculosis Beijing genotype. The polymorphisms examined were not associated with M. tuberculosis induced cytokines, except for a polymorphism in ATG10, which was linked with IL-8 production (p = 0.04). All associations found lost statistical significance after correction for multiple testing. This first examination of a broad set of polymorphisms in autophagy genes fails to show a clear association with TB, with M. tuberculosis Beijing genotype infection or with ex-vivo pro-inflammatory cytokine production. PMID:22879892

  1. Gene expression profiles of autophagy-related genes in multiple sclerosis.

    PubMed

    Igci, Mehri; Baysan, Mehmet; Yigiter, Remzi; Ulasli, Mustafa; Geyik, Sirma; Bayraktar, Recep; Bozgeyik, İbrahim; Bozgeyik, Esra; Bayram, Ali; Cakmak, Ecir Ali

    2016-08-15

    Multiple sclerosis (MS) is an imflammatory disease of central nervous system caused by genetic and environmental factors that remain largely unknown. Autophagy is the process of degradation and recycling of damaged cytoplasmic organelles, macromolecular aggregates, and long-lived proteins. Malfunction of autophagy contributes to the pathogenesis of neurological diseases, and autophagy genes may modulate the T cell survival. We aimed to examine the expression levels of autophagy-related genes. The blood samples of 95 unrelated patients (aged 17-65years, 37 male, 58 female) diagnosed as MS and 95 healthy controls were used to extract the RNA samples. After conversion to single stranded cDNA using polyT priming: the targeted genes were pre-amplified, and 96×78 (samples×primers) qRT-PCR reactions were performed for each primer pair on each sample on a 96.96 array of Fluidigm BioMark™. Compared to age- and sex-matched controls, gene expression levels of ATG16L2, ATG9A, BCL2, FAS, GAA, HGS, PIK3R1, RAB24, RGS19, ULK1, FOXO1, HTT were significantly altered (false discovery rate<0.05). Thus, altered expression levels of several autophagy related genes may affect protein levels, which in turn would influence the activity of autophagy, or most probably, those genes might be acting independent of autophagy and contributing to MS pathogenesis as risk factors. The indeterminate genetic causes leading to alterations in gene expressions require further analysis. PMID:27125224

  2. Harnessing autophagy for cell fate control gene therapy.

    PubMed

    Felizardo, Tania C; Foley, Jason; Steed, Kevin; Dropulic, Boro; Amarnath, Shoba; Medin, Jeffrey A; Fowler, Daniel H

    2013-07-01

    We hypothesized that rapamycin, through induction of autophagy and promotion of an antiapoptotic phenotype, would permit lentiviral (LV)-based transgene delivery to human T-Rapa cells, which are being tested in phase II clinical trials in the setting of allogeneic hematopoietic cell transplantation. Manufactured T-Rapa cells were exposed to supernatant enriched for a LV vector encoding a fusion protein consisting of truncated CD19 (for cell surface marking) and DTYMK/TMPKΔ, which provides "cell-fate control" due to its ability to phosphorylate (activate) AZT prodrug. LV-transduction in rapamycin-treated T-Rapa cells: (1) resulted in mitochondrial autophagy and a resultant antiapoptotic phenotype, which was reversed by the autophagy inhibitor 3-MA; (2) yielded changes in MAP1LC3B and SQSTM1 expression, which were reversed by 3-MA; and (3) increased T-Rapa cell expression of the CD19-DTYMKΔ fusion protein, despite their reduced proliferative status. Importantly, although the transgene-expressing T-Rapa cells expressed an antiapoptotic phenotype, they were highly susceptible to cell death via AZT exposure both in vitro and in vivo (in a human-into-mouse xenogeneic transplantation model). Therefore, rapamycin induction of T cell autophagy can be used for gene therapy applications, including the CD19-DTYMKΔ cell-fate control axis to improve the safety of T cell immuno-gene therapy. PMID:23633667

  3. mir-30d Regulates multiple genes in the autophagy pathway and impairs autophagy process in human cancer cells

    SciTech Connect

    Yang, Xiaojun; Zhong, Xiaomin; Tanyi, Janos L.; Shen, Jianfeng; Xu, Congjian; Gao, Peng; Zheng, Tim M.; DeMichele, Angela; Zhang, Lin

    2013-02-15

    Highlights: ► Gene set enrichment analysis indicated mir-30d might regulate the autophagy pathway. ► mir-30d represses the expression of BECN1, BNIP3L, ATG12, ATG5 and ATG2. ► BECN1, BNIP3L, ATG12, ATG5 and ATG2 are direct targets of mir-30d. ► mir-30d inhibits autophagosome formation and LC3B-I conversion to LC3B-II. ► mir-30d regulates the autophagy process. -- Abstract: In human epithelial cancers, the microRNA (miRNA) mir-30d is amplified with high frequency and serves as a critical oncomir by regulating metastasis, apoptosis, proliferation, and differentiation. Autophagy, a degradation pathway for long-lived protein and organelles, regulates the survival and death of many cell types. Increasing evidence suggests that autophagy plays an important function in epithelial tumor initiation and progression. Using a combined bioinformatics approach, gene set enrichment analysis, and miRNA target prediction, we found that mir-30d might regulate multiple genes in the autophagy pathway including BECN1, BNIP3L, ATG12, ATG5, and ATG2. Our further functional experiments demonstrated that the expression of these core proteins in the autophagy pathway was directly suppressed by mir-30d in cancer cells. Finally, we showed that mir-30d regulated the autophagy process by inhibiting autophagosome formation and LC3B-I conversion to LC3B-II. Taken together, our results provide evidence that the oncomir mir-30d impairs the autophagy process by targeting multiple genes in the autophagy pathway. This result will contribute to understanding the molecular mechanism of mir-30d in tumorigenesis and developing novel cancer therapy strategy.

  4. Alpha-lipoic acid protects cardiomyocytes against hypoxia/reoxygenation injury by inhibiting autophagy

    SciTech Connect

    Cao, Xueming; Chen, Aihua Yang, Pingzhen; Song, Xudong; Liu, Yingfeng; Li, Zhiliang; Wang, Xianbao; Wang, Lizi; Li, Yunpeng

    2013-11-29

    Highlights: •We observed the cell viability and death subjected to H/R in H9c2 cardiomyocytes. •We observed the degree of autophagy subjected to H/R in H9c2 cardiomyocytes. •LA inhibited the degree of autophagy in parallel to the enhanced cell survival. •LA inhibited the autophagy in parallel to the decreased total cell death. •We concluded that LA protected cardiomyocytes against H/R by inhibiting autophagy. -- Abstract: Hypoxia/reoxygenation (H/R) is an important in vitro model for exploring the molecular mechanisms and functions of autophagy during myocardial ischemia/reperfusion (I/R). Alpha-lipoic acid (LA) plays an important role in the etiology of cardiovascular disease. Autophagy is widely implicated in myocardial I/R injury. We assessed the degree of autophagy by pretreatment with LA exposed to H/R in H9c2 cell based on the expression levels of Beclin-1, LC3II/LC3I, and green fluorescent protein-labeled LC3 fusion proteins. Autophagic vacuoles were confirmed in H9c2 cells exposed to H/R using transmission electron microscopy. Our findings indicated that pretreatment with LA inhibited the degree of autophagy in parallel to the enhanced cell survival and decreased total cell death in H9c2 cells exposed to H/R. We conclude that LA protects cardiomyocytes against H/R injury by inhibiting autophagy.

  5. RNAi-Mediated Inactivation of Autophagy Genes in Caenorhabditis elegans.

    PubMed

    Palmisano, Nicholas J; Meléndez, Alicia

    2016-02-01

    RNA interference (RNAi) is a process that results in the sequence-specific silencing of endogenous mRNA through the introduction of double-stranded RNA (dsRNA). In the nematode Caenorhabditis elegans, RNA inactivation can be used at any specific developmental stage or during adulthood to inhibit a given target gene. Investigators can take advantage of the fact that, in C. elegans, RNAi is unusual in that it is systemic, meaning that dsRNA can spread throughout the animal and can affect virtually all tissues except neurons. Here, we describe a protocol for the most common method to achieve RNAi in C. elegans, which is to feed them bacteria that express dsRNA complementary to a specific target gene. This method has various advantages, including the availability of libraries that essentially cover the whole genome, the ability to treat animals at any developmental stage, and that it is relatively cost effective. We also discuss how RNAi specific to autophagy genes has proven to be an excellent method to study the role of these genes in autophagy, as well as other cellular and developmental processes, while also highlighting the caveats that must be applied. PMID:26832686

  6. Autophagy plays a protective role in cell death of osteoblasts exposure to lead chloride.

    PubMed

    Lv, Xiao-hua; Zhao, Da-hang; Cai, Shi-zhong; Luo, Shi-ying; You, Tingting; Xu, Bi-lian; Chen, Ke

    2015-12-01

    Lead (Pb) is a toxic heavy metal widespreadly used in industrial field. Prior studies showed that Pb exposure had detrimental effects on osteoblasts. The mechanisms underlying Pb-induced damage are complex. Autophagy can protect cells from various cytotoxic stimuli. In the present study, the aim of our research was to investigate whether Pb could activate autophagy to play a protective role against osteoblasts apoptosis. Our results indicated that PbCl2 induced autophagy and autophagic flux in MC3T3-E1 murine osteoblastic cell by RT-PCR, western blot, as well as fluorescence microscopy analysis of GFP-LC3, AO and MDC staining. Pb increased the apoptosis of osteoblasts, evidenced by western blot and Hoechst 33258 staining assessment. In addition, inhibiting autophagy by 3-MA further increased the osteoblasts apoptosis after Pb exposure, showed by flow cytometry and Hoechst 33258 staining. Furthermore, phosphorylation of mTOR and p70S6K was inhibited by Pb exposure, indicating that Pb might induce autophagy in osteoblasts via inhibiting mTOR pathway. Altogether, these evidence suggested that Pb exporsure promoted autophagy flux in osteoblasts. The activation of autophagy by Pb played a protective role in osteoblasts apoptosis, which might be mediated through the mTOR pathway. PMID:26383630

  7. Ghrelin protects infarcted myocardium by induction of autophagy and AMP-activated protein kinase pathway.

    PubMed

    Yuan, Ming-Jie; Kong, Bin; Wang, Tao; Wang, Xin; Huang, He; Maghsoudi, Taneen

    2016-08-01

    The majority of studies have reported that enhancing autophagy in the myocardium is cardioprotective. Here, we tested the hypothesis that ghrelin, a growth hormone-releasing peptide, will protect infarcted myocardium by inducing of autophagy. Myocardial infarction was induced in mice by left coronary artery ligation the surviving mice 24 h after surgical were started on 2 week treatments with one of the following: vehicle, acylated ghrelin(50 mg/kg per day) or acylated ghrelin plus 3-MA(an autophagy inhibitor, 15 mg/kg, per day). We found that ghrelin significantly improved the cardiac function, and autophagy was enhanced by elevated LC3-II/LC-I ratio and mRNA expression of autophagy related protein. In vitro, cultured neonatal rat ventricular cardiomyocytes were subjected to simulate ischemia/reperfusion, 3-MA significantly attenuated ghrelin-induced autophagy, which was associated with activated AMP-activated protein kinase (AMPK) signal pathway. Moreover, ghrelin reduced cell death, and RNAi-mediated knockdown of autophagy protein 5 (Atg5) partly abolished ghrelin's cardioprotective effect. It is the first time to demonstrate that the cardioprotective effect of ghrelin on ischemia myocardium in part through regulating of autophagy signal pathway. PMID:27235554

  8. Autophagy confers DNA damage repair pathways to protect the hematopoietic system from nuclear radiation injury

    PubMed Central

    Lin, Weiwei; Yuan, Na; Wang, Zhen; Cao, Yan; Fang, Yixuan; Li, Xin; Xu, Fei; Song, Lin; Wang, Jian; Zhang, Han; Yan, Lili; Xu, Li; Zhang, Xiaoying; Zhang, Suping; Wang, Jianrong

    2015-01-01

    Autophagy is essentially a metabolic process, but its in vivo role in nuclear radioprotection remains unexplored. We observed that ex vivo autophagy activation reversed the proliferation inhibition, apoptosis, and DNA damage in irradiated hematopoietic cells. In vivo autophagy activation improved bone marrow cellularity following nuclear radiation exposure. In contrast, defective autophagy in the hematopoietic conditional mouse model worsened the hematopoietic injury, reactive oxygen species (ROS) accumulation and DNA damage caused by nuclear radiation exposure. Strikingly, in vivo defective autophagy caused an absence or reduction in regulatory proteins critical to both homologous recombination (HR) and non-homologous end joining (NHEJ) DNA damage repair pathways, as well as a failure to induce these proteins in response to nuclear radiation. In contrast, in vivo autophagy activation increased most of these proteins in hematopoietic cells. DNA damage assays confirmed the role of in vivo autophagy in the resolution of double-stranded DNA breaks in total bone marrow cells as well as bone marrow stem and progenitor cells upon whole body irradiation. Hence, autophagy protects the hematopoietic system against nuclear radiation injury by conferring and intensifying the HR and NHEJ DNA damage repair pathways and by removing ROS and inhibiting apoptosis. PMID:26197097

  9. Autophagy Protects against CYP2E1/Chronic Ethanol-Induced Hepatotoxicity

    PubMed Central

    Lu, Yongke; Cederbaum, Arthur I.

    2015-01-01

    Autophagy is an intracellular pathway by which lysosomes degrade and recycle long-lived proteins and cellular organelles. The effects of ethanol on autophagy are complex but recent studies have shown that autophagy serves a protective function against ethanol-induced liver injury. Autophagy was found to also be protective against CYP2E1-dependent toxicity in vitro in HepG2 cells which express CYP2E1 and in vivo in an acute alcohol/CYPE1-dependent liver injury model. The goal of the current report was to extend the previous in vitro and acute in vivo experiments to a chronic ethanol model to evaluate whether autophagy is also protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. Wild type (WT), CYP2E1 knockout (KO) or CYP2E1 humanized transgenic knockin (KI), mice were fed an ethanol liquid diet or control dextrose diet for four weeks. In the last week, some mice received either saline or 3-methyladenine (3-MA), an inhibitor of autophagy, or rapamycin, which stimulates autophagy. Inhibition of autophagy by 3-MA potentiated the ethanol-induced increases in serum transaminase and triglyceride levels in the WT and KI mice but not KO mice, while rapamycin prevented the ethanol liver injury. Treatment with 3-MA enhanced the ethanol-induced fat accumulation in WT mice and caused necrosis in the KI mice; little or no effect was found in the ethanol-fed KO mice or any of the dextrose-fed mice. 3-MA treatment further lowered the ethanol-decrease in hepatic GSH levels and further increased formation of TBARS in WT and KI mice, whereas rapamycin blunted these effects of ethanol. Neither 3-MA nor rapamycin treatment affected CYP2E1 catalytic activity or content or the induction CYP2E1 by ethanol. The 3-MA treatment decreased levels of Beclin-1 and Atg 7 but increased levels of p62 in the ethanol-fed WT and KI mice whereas rapamycin had the opposite effects, validating inhibition and stimulation of autophagy, respectively. These results suggest

  10. Heat Shock Protein 72 Enhances Autophagy as a Protective Mechanism in Lipopolysaccharide-Induced Peritonitis in Rats

    PubMed Central

    Li, Shu; Zhou, Yi; Fan, Jinjin; Cao, Shirong; Cao, Tao; Huang, Fengxian; Zhuang, Shougang; Wang, Yihan; Yu, Xueqing; Mao, Haiping

    2011-01-01

    Peritoneal dialysis–related peritonitis causes the denudation of mesothelial cells and, ultimately, membrane integrity alterations and peritoneal dysfunction. Because heat shock protein 72 (HSP72) confers protection against apoptosis and because autophagy mediates survival in response to cellular stresses, we examined whether autophagy contributes to HSP72-mediated cytoprotection in lipopolysaccharide (LPS)-induced peritonitis. Exposure of cultured peritoneal mesothelial cells to LPS resulted first in autophagy and later, apoptosis. Inhibition of autophagy by 3-methyladenine or Beclin-1 small-interfering RNA sensitized cells to apoptosis and abolished the antiapoptotic effect of HSP72, suggesting that autophagy activation acts as a prosurvival mechanism. Overexpression of HSP72 augmented autophagy through c-Jun N-terminal kinase (JNK) phosphorylation and Beclin-1 up-regulation. Suppression of JNK activity reversed HSP72-mediated Beclin-1 up-regulation and autophagy, indicating that HSP72-mediated autophagy is JNK dependent. In a rat model of LPS-associated peritonitis, autophagy occurred before apoptosis in peritoneum. Up-regulation of HSP72 by geranylgeranylacetone increased autophagy, inhibited apoptosis, and attenuated peritoneal injury, and these effects were blunted by down-regulation of HSP72 with quercetin. Additionally, blocking autophagy by chloroquine promoted apoptosis and aggravated LPS-associated peritoneal dysfunction. Thus, HSP72 protects peritoneum from LPS-induced mesothelial cells injury, at least in part by enhancing JNK activation–dependent autophagy and inhibiting apoptosis. These findings imply that HSP72 induction might be a potential therapy for peritonitis. PMID:22001349

  11. 20-hydroxyecdysone upregulates Atg genes to induce autophagy in the Bombyx fat body

    PubMed Central

    Tian, Ling; Ma, Li; Guo, Enen; Deng, Xiaojuan; Ma, Sanyuan; Xia, Qingyou; Cao, Yang; Li, Sheng

    2013-01-01

    Autophagy is finely regulated at multiple levels and plays crucial roles in development and disease. In the fat body of the silkworm, Bombyx mori, autophagy occurs and Atg gene expression peaks during the nonfeeding molting and pupation stages when the steroid hormone (20-hydroxyecdysone; 20E) is high. Injection of 20E into the feeding larvae upregulated Atg genes and reduced TORC1 activity resulting in autophagy induction in the fat body. Conversely, RNAi knockdown of the 20E receptor partner (USP) or targeted overexpression of a dominant negative mutant of the 20E receptor (EcRDN) in the larval fat body reduced autophagy and downregulated the Atg genes, confirming the importance of 20E-induction of Atg gene expression during pupation. Moreover, in vitro treatments of the larval fat body with 20E upregulated the Atg genes. Five Atg genes were potentially 20E primary-responsive, and a 20E response element was identified in the Atg1 (ortholog of human ULK1) promoter region. Furthermore, RNAi knockdown of 4 key genes (namely Br-C, E74, HR3 and βftz-F1) in the 20E-triggered transcriptional cascade reduced autophagy and downregulated Atg genes to different levels. Taken together, we conclude that in addition to blocking TORC1 activity for autophagosome initiation, 20E upregulates Atg genes to induce autophagy in the Bombyx fat body. PMID:23674061

  12. Cannabinoid-induced autophagy: Protective or death role?

    PubMed

    Costa, Lia; Amaral, Cristina; Teixeira, Natércia; Correia-da-Silva, Georgina; Fonseca, Bruno M

    2016-01-01

    Autophagy, the "self-digestion" mechanism of the cells, is an evolutionary conserved catabolic process that targets portions of cytoplasm, damaged organelles and proteins for lysosomal degradation, which plays a crucial role in development and disease. Cannabinoids are active compounds of Cannabis sativa and the most prevalent psychoactive substance is Δ(9)-tetrahydrocannabinol (THC). Cannabinoid compounds can be divided in three types: the plant-derived natural products (phytocannabinoids), the cannabinoids produced endogenously (endocannabinoids) and the synthesized compounds (synthetic cannabinoids). Various studies reported a cannabinoid-induced autophagy mechanism in cancer and non-cancer cells. In this review we focus on the recent advances in the cannabinoid-induced autophagy and highlight the molecular mechanisms involved in these processes. PMID:26732541

  13. Induction of cyto-protective autophagy by paramontroseite VO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Miao, Yanyan; Zhang, Yunjiao; Liu, Liang; Lin, Jun; Yang, James Y.; Xie, Yi; Wen, Longping

    2013-04-01

    A variety of inorganic nanomaterials have been shown to induce autophagy, a cellular degradation process critical for the maintenance of cellular homeostasis. The overwhelming majority of autophagic responses elicited by nanomaterials were detrimental to cell fate and contributed to increased cell death. A widely held view is that the inorganic nanoparticles, when encapsulated and trapped by autophagosomes, may compromise the normal autophagic process due to the inability of the cells to degrade these materials and thus they manifest a detrimental effect on the well-being of a cell. Here we show that, contrary to this notion, nano-sized paramontroseite VO2 nanocrystals (P-VO2) induced cyto-protective, rather than death-promoting, autophagy in cultured HeLa cells. P-VO2 also caused up-regulation of heme oxygenase-1 (HO-1), a cellular protein with a demonstrated role in protecting cells against death under stress situations. The autophagy inhibitor 3-methyladenine significantly inhibited HO-1 up-regulation and increased the rate of cell death in cells treated with P-VO2, while the HO-1 inhibitor protoporphyrin IX zinc (II) (ZnPP) enhanced the occurrence of cell death in the P-VO2-treated cells while having no effect on the autophagic response induced by P-VO2. On the other hand, Y2O3 nanocrystals, a control nanomaterial, induced death-promoting autophagy without affecting the level of expression of HO-1, and the pro-death effect of the autophagy induced by Y2O3. Our results represent the first report on a novel nanomaterial-induced cyto-protective autophagy, probably through up-regulation of HO-1, and may point to new possibilities for exploiting nanomaterial-induced autophagy for therapeutic applications.

  14. Genetic Variation in Autophagy-Related Genes Influences the Risk and Phenotype of Buruli Ulcer

    PubMed Central

    Capela, Carlos; Dossou, Ange Dodji; Silva-Gomes, Rita; Sopoh, Ghislain Emmanuel; Makoutode, Michel; Menino, João Filipe; Fraga, Alexandra Gabriel; Cunha, Cristina; Carvalho, Agostinho; Rodrigues, Fernando; Pedrosa, Jorge

    2016-01-01

    Introduction Buruli ulcer (BU) is a severe necrotizing human skin disease caused by Mycobacterium ulcerans. Clinically, presentation is a sum of these diverse pathogenic hits subjected to critical immune-regulatory mechanisms. Among them, autophagy has been demonstrated as a cellular process of critical importance. Since microtubules and dynein are affected by mycolactone, the critical pathogenic exotoxin produced by M. ulcerans, cytoskeleton-related changes might potentially impair the autophagic process and impact the risk and progression of infection. Objective Genetic variants in the autophagy-related genes NOD2, PARK2 and ATG16L1 has been associated with susceptibility to mycobacterial diseases. Here, we investigated their association with BU risk, its severe phenotypes and its progression to an ulcerative form. Methods Genetic variants were genotyped using KASPar chemistry in 208 BU patients (70.2% with an ulcerative form and 28% in severe WHO category 3 phenotype) and 300 healthy endemic controls. Results The rs1333955 SNP in PARK2 was significantly associated with increased susceptibility to BU [odds ratio (OR), 1.43; P = 0.05]. In addition, both the rs9302752 and rs2066842 SNPs in NOD2 gee significantly increased the predisposition of patients to develop category 3 (OR, 2.23; P = 0.02; and OR 12.7; P = 0.03, respectively, whereas the rs2241880 SNP in ATG16L1 was found to significantly protect patients from presenting the ulcer phenotype (OR, 0.35; P = 0.02). Conclusion Our findings indicate that specific genetic variants in autophagy-related genes influence susceptibility to the development of BU and its progression to severe phenotypes. PMID:27128681

  15. Autophagy in Health and Disease: A Double-Edged Sword

    PubMed Central

    Shintani, Takahiro; Klionsky, Daniel J.

    2006-01-01

    Autophagy, the process by which cells recycle cytoplasm and dispose of excess or defective organelles, has entered the research spotlight largely owing to the discovery of the protein components that drive this process. Identifying the autophagy genes in yeast and finding orthologs in other organisms reveals the conservation of the mechanism of autophagy in eukaryotes and allows the use of molecular genetics and biology in different model systems to study this process. By mostly morphological studies, autophagy has been linked to disease processes. Whether autophagy protects from or causes disease is unclear. Here, we summarize current knowledge about the role of autophagy in disease and health. PMID:15528435

  16. Heme oxygenase-1 enhances autophagy in podocytes as a protective mechanism against high glucose-induced apoptosis

    SciTech Connect

    Dong, Chenglong; Zheng, Haining; Huang, Shanshan; You, Na; Xu, Jiarong; Ye, Xiaolong; Zhu, Qun; Feng, Yamin; You, Qiang; Miao, Heng; Ding, Dafa; Lu, Yibing

    2015-10-01

    Injury and loss of podocytes play vital roles in diabetic nephropathy progression. Emerging evidence suggests autophagy, which is induced by multiple stressors including hyperglycemia, plays a protective role. Meanwhile, heme oxygenase-1 (HO-1) possesses powerful anti-apoptotic properties. Therefore, we investigated the impact of autophagy on podocyte apoptosis under diabetic conditions and its association with HO-1. Mouse podocytes were cultured in vitro; apoptosis was detected by flow cytometry. Transmission electron microscopy and biochemical autophagic flux assays were used to measure the autophagy markers microtubule-associated protein 1 light chain 3-II (LC3-II) and beclin-1. LC3-II and beclin-1 expression peaked 12–24 h after exposing podocytes to high glucose. Inhibition of autophagy with 3-methyladenine or Beclin-1 siRNAs or Atg 5 siRNAs sensitized cells to apoptosis, suggesting autophagy is a survival mechanism. HO-1 inactivation inhibited autophagy, which aggravated podocyte injury in vitro. Hemin-induced autophagy also protected podocytes from hyperglycemia in vitro and was abrogated by HO-1 siRNA. Adenosine monophosphate-activated protein kinase phosphorylation was higher in hemin-treated and lower in HO-1 siRNA-treated podocytes. Suppression of AMPK activity reversed HO-1-mediated Beclin-1 upregulation and autophagy, indicating HO-1-mediated autophagy is AMPK dependent. These findings suggest HO-1 induction and regulation of autophagy are potential therapeutic targets for diabetic nephropathy. - Highlights: • High glucose leads to increased autophagy in podocytes at an early stage. • The early autophagic response protects against high glucose-induced apoptosis. • Heme oxygenase-1 enhances autophagy and decreases high glucose -mediated apoptosis. • Heme oxygenase-1 induces autophagy through the activation of AMPK.

  17. Lack of Connection Between Midgut Cell Autophagy Gene Expression and BmCPV Infection in the Midgut of Bombyx mori

    PubMed Central

    Yang, Xiaobing; Wu, Suli; Wu, Yongpeng; Liu, Yang; Qian, Yonghua; Jiao, Feng

    2015-01-01

    Autophagy is associated with multiple biological processes and has protective and defensive functions with respect to immunity, inflammation, and resistance to microbial infection. In this experiment, we wished to investigate whether autophagy is a factor in the midgut cell response of Bombyx mori to infection by the B. mori cytoplasmic polyhedrosis virus (BmCPV). Our results indicated that the expression of three autophagy-related genes (BmAtg8, BmAtg5, and BmAtg7) in the midgut did not change greatly after BmCPV infection in B. mori. Basal ATG8/ATG8PE protein expression was detected in different B. mori tissues by using western blot analysis. Immunohistochemistry showed that the ATG8/ATG8PE proteins were located mainly in the cytoplasm. ATG8/ATG8PE protein levels decreased at 12 and 16 h after BmCPV infection. Our results indicate that autophagy responded slightly to BmCPV infection, but could not prevent the invasion and replication of the virus. PMID:26163666

  18. Gene Network Exploration of Crosstalk between Apoptosis and Autophagy in Chronic Myelogenous Leukemia

    PubMed Central

    Cho, William C. S.; Chan, Lawrence W. C.; Wong, S. C. Cesar; Tsui, Nancy B. Y.; Siu, Parco M.; Yip, S. P.; Yung, Benjamin Y. M.

    2015-01-01

    Background. Gene expression levels change to adapt the stress, such as starvation, toxin, and radiation. The changes are signals transmitted through molecular interactions, eventually leading to two cellular fates, apoptosis and autophagy. Due to genetic variations, the signals may not be effectively transmitted to modulate apoptotic and autophagic responses. Such aberrant modulation may lead to carcinogenesis and drug resistance. The balance between apoptosis and autophagy becomes very crucial in coping with the stress. Though there have been evidences illustrating the apoptosis-autophagy interplay, the underlying mechanism and the participation of the regulators including transcription factors (TFs) and microRNAs (miRNAs) remain unclear. Results. Gene network is a graphical illustration for exploring the functional linkages and the potential coordinate regulations of genes. Microarray dataset for the study of chronic myeloid leukemia was obtained from Gene Expression Omnibus. The expression profiles of those genes related to apoptosis and autophagy, including MCL1, BCL2, ATG, beclin-1, BAX, BAK, E2F, cMYC, PI3K, AKT, BAD, and LC3, were extracted from the dataset to construct the gene networks. Conclusion. The network analysis of these genes explored the underlying mechanisms and the roles of TFs and miRNAs for the crosstalk between apoptosis and autophagy. PMID:25821802

  19. Autophagy and ethanol neurotoxicity

    PubMed Central

    Luo, Jia

    2015-01-01

    Excessive ethanol exposure is detrimental to the brain. The developing brain is particularly vulnerable to ethanol such that prenatal ethanol exposure causes fetal alcohol spectrum disorders (FASD). Neuronal loss in the brain is the most devastating consequence and is associated with mental retardation and other behavioral deficits observed in FASD. Since alcohol consumption during pregnancy has not declined, it is imperative to elucidate the underlying mechanisms and develop effective therapeutic strategies. One cellular mechanism that acts as a protective response for the central nervous system (CNS) is autophagy. Autophagy regulates lysosomal turnover of organelles and proteins within cells, and is involved in cell differentiation, survival, metabolism, and immunity. We have recently shown that ethanol activates autophagy in the developing brain. The autophagic preconditioning alleviates ethanol-induced neuron apoptosis, whereas inhibition of autophagy potentiates ethanol-stimulated reactive oxygen species (ROS) and exacerbates ethanol-induced neuroapoptosis. The expression of genes encoding proteins required for autophagy in the CNS is developmentally regulated; their levels are much lower during an ethanol-sensitive period than during an ethanol-resistant period. Ethanol may stimulate autophagy through multiple mechanisms; these include induction of oxidative stress and endoplasmic reticulum stress, modulation of MTOR and AMPK signaling, alterations in BCL2 family proteins, and disruption of intracellular calcium (Ca2+) homeostasis. This review discusses the most recent evidence regarding the involvement of autophagy in ethanol-mediated neurotoxicity as well as the potential therapeutic approach of targeting autophagic pathways. PMID:25484085

  20. Autophagy induced by p53-reactivating molecules protects pancreatic cancer cells from apoptosis.

    PubMed

    Fiorini, Claudia; Menegazzi, Marta; Padroni, Chiara; Dando, Ilaria; Dalla Pozza, Elisa; Gregorelli, Alex; Costanzo, Chiara; Palmieri, Marta; Donadelli, Massimo

    2013-03-01

    TP53 mutations compromising p53 transcriptional function occur in more than 50 % of human cancers, including pancreatic adenocarcinoma, and render cancer cells more resistant to conventional therapy. In the last few years, many efforts have been addressed to identify p53-reactivating molecules able to restore the wild-type transcriptionally competent conformation of the mutated proteins. Here, we show that two of these compounds, CP-31398 and RITA, induce cell growth inhibition, apoptosis, and autophagy by activating p53/DNA binding and p53 phosphorylation (Ser15), without affecting the total p53 amount. These effects occur in both wild-type and mutant p53 pancreatic adenocarcinoma cell lines, whereas they are much less pronounced in normal human primary fibroblasts. Furthermore, CP-31398 and RITA regulate the axis SESN1-2/AMPK/mTOR by inducing AMPK phosphorylation on Thr172, which has a crucial role in the autophagic response. The protective role of autophagy in cell growth inhibition by CP-31398 and RITA is supported by the finding that the AMPK inhibitor compound C or the autophagy inhibitors chloroquine or 3-methyladenine sensitize both pancreatic adenocarcinoma cell lines to the apoptotic response induced by p53-reactivating molecules. Our results demonstrate for the first time a survival role for autophagy induced by p53-reactivating molecules, supporting the development of an anti-cancer therapy based on autophagy inhibition associated to p53 activation. PMID:23238993

  1. Orientin protects myocardial cells against hypoxia-reoxygenation injury through induction of autophagy.

    PubMed

    Liu, Liya; Wu, Youxi; Huang, Xiulan

    2016-04-01

    Orientin, a flavonoid exists in Chinese traditional herbal Polygonum orientale L., has been previously demonstrated to protect against myocardial ischemia reperfusion injury (MIRI) through inhibition of apoptosis. However, the underlying mechanisms remain to be elucidated and we therefore in this study investigated the effects of orientin on autophagy during MIRI in rats. The results indicate that orientin, at the concentrations of 10 and 30 μM in the cultures of neonatal rat cardiomyocytes, promoted the induction of autophagy, increasing the formation of autophagosomes and enhancing the expression of LC3 puncta, LC3-II/LC3-I ratio and Beclin 1 after hypoxia/reoxygenation. The induction of autophagy by orientin correlated with enhanced cell viability and decreased apoptosis, which was significantly attenuated by autophagy inhibitor wortmannin, a phosphatidylinositol-3-kinase (PI3K) inhibitor. Moreover, application of orientin increased the activation of AMPK and Akt, downregulated the phosphorylation of mammalian target of rapamycin (mTOR) and the expression of Raptor, and enhanced the interaction between Beclin 1 and Bcl-2 in endoplasmic reticulum due to increased phosphorylation of Beclin 1 and decreased phosphorylation of Bcl-2. Our investigation suggests that the cardioprotective effects of orientin during MIRI may be mediated through the balance of autophagy through regulating AMPK, Akt, mTOR, and Bcl-2 associated signaling pathways. PMID:26875637

  2. Autophagy protects cardiomyocytes from the myocardial ischaemia-reperfusion injury through the clearance of CLP36

    PubMed Central

    Li, Shiguo; Liu, Chao; Gu, Lei; Wang, Lina; Shang, Yongliang; Liu, Qiong; Wan, Junyi; Shi, Jian; Wang, Fang; Xu, Zhiliang; Ji, Guangju

    2016-01-01

    Cardiovascular disease (CVD) is the leading cause of the death worldwide. An increasing number of studies have found that autophagy is involved in the progression or prevention of CVD. However, the precise mechanism of autophagy in CVD, especially the myocardial ischaemia-reperfusion injury (MI/R injury), is unclear and controversial. Here, we show that the cardiomyocyte-specific disruption of autophagy by conditional knockout of Atg7 leads to severe contractile dysfunction, myofibrillar disarray and vacuolar cardiomyocytes. A negative cytoskeleton organization regulator, CLP36, was found to be accumulated in Atg7-deficient cardiomyocytes. The cardiomyocyte-specific knockout of Atg7 aggravates the MI/R injury with cardiac hypertrophy, contractile dysfunction, myofibrillar disarray and severe cardiac fibrosis, most probably due to CLP36 accumulation in cardiomyocytes. Altogether, this work reveals autophagy may protect cardiomyocytes from the MI/R injury through the clearance of CLP36, and these findings define a novel relationship between autophagy and the regulation of stress fibre in heart. PMID:27512143

  3. Ionizing Irradiation Protection and Mitigation of Murine Cells by Carbamazepine Is p53 and Autophagy Independent

    PubMed Central

    Kim, Hyun; Bernard, Mark E.; Farkas, Amy; Goff, Julie; Kalash, Ronny; Houghton, Frank; Shields, Donna; Franicola, Darcy; Dixon, Tracy; Zhang, Xichen; Epperly, Michael; Wang, Hong; Cobanoglu, Murat Can; Greenberger, Joel S.

    2012-01-01

    Background Carbamazepine, a sodium channel blocker and pro-autophagy agent used in the treatment of epilepsy and trigeminal neuralgia, is also an ionizing radiation mitigator and protector. Materials and Methods We measured the effect of carbamazepine, compared to other pro-autophagy drugs (i.e. lithium and valproic acid), on irradiation of autophagy incompetent (Atg5−/−) and competent (Atg5+/+) mouse embryonic fibroblasts, p53−/− and p53+/+ bone marrow stromal cells, and human IB3, KM101, HeLa, and umbilical cord blood cells, and in total body-irradiated or orthotopic tumor-bearing mice. Results Carbamazepine, but not other pro-autophagy drugs, was a radiation protector and mitigator for mouse cell lines, independent of apoptosis, autophagy, p53, antioxidant store depletion, and class I phosphatidylinositol 3-kinase, but was ineffective with human cells. Carbamazepine was effective when delivered 24 hours before or 12 hours after total body irradiation of C57BL/6HNsd mice and did not protect orthotopic Lewis lung tumors. Conclusion Carbamazepine is a murine radiation protector and mitigator. PMID:22523285

  4. Systematic cloning and analysis of autophagy-related genes from the silkworm Bombyx mori

    PubMed Central

    Zhang, Xuan; Hu, Zhan-Ying; Li, Wei-Fang; Li, Qing-Rong; Deng, Xiao-Juan; Yang, Wan-Ying; Cao, Yang; Zhou, Cong-Zhao

    2009-01-01

    Background Through the whole life of eukaryotes, autophagy plays an important role in various biological events including development, differentiation and determination of lifespan. A full set of genes and their encoded proteins of this evolutionarily conserved pathway have been identified in many eukaryotic organisms from yeast to mammals. However, this pathway in the insect model organism, the silkworm Bombyx mori, remains poorly investigated. Results Based on the autophagy pathway in several model organisms and a series of bioinformatic analyses, we have found more than 20 autophagy-related genes from the current database of the silkworm Bombyx mori. These genes could be further classified into the signal transduction pathway and two ubiquitin-like pathways. Using the mRNA extracted from the silkgland, we cloned the full length cDNA fragments of some key genes via reverse transcription PCR and 3' rapid amplification of cDNA ends (RACE). In addition, we found that the transcription levels of two indicator genes BmATG8 and BmATG12 in the silkgland tend to be increased from 1st to 8th day of the fifth instar larvae. Conclusion Bioinformatics in combination with RT-PCR enable us to remodel a preliminary pathway of autophagy in the silkworm. Amplification and cloning of most autophagy-related genes from the silkgland indicated autophagy is indeed an activated process. Furthermore, the time-course transcriptional profiles of BmATG8 and BmATG12 revealed that both genes are up-regulated along the maturation of the silkgland during the fifth instar. These findings suggest that the autophagy should play an important role in Bombyx mori silkgland. PMID:19470186

  5. Truncating mutation in the autophagy gene UVRAG confers oncogenic properties and chemosensitivity in colorectal cancers

    PubMed Central

    He, Shanshan; Zhao, Zhen; Yang, Yongfei; O'Connell, Douglas; Zhang, Xiaowei; Oh, Soohwan; Ma, Binyun; Lee, Joo-Hyung; Zhang, Tian; Varghese, Bino; Yip, Janae; Dolatshahi Pirooz, Sara; Li, Ming; Zhang, Yong; Li, Guo-Min; Ellen Martin, Sue; Machida, Keigo; Liang, Chengyu

    2015-01-01

    Autophagy-related factors are implicated in metabolic adaptation and cancer metastasis. However, the role of autophagy factors in cancer progression and their effect in treatment response remain largely elusive. Recent studies have shown that UVRAG, a key autophagic tumour suppressor, is mutated in common human cancers. Here we demonstrate that the cancer-related UVRAG frameshift (FS), which does not result in a null mutation, is expressed as a truncated UVRAGFS in colorectal cancer (CRC) with microsatellite instability (MSI), and promotes tumorigenesis. UVRAGFS abrogates the normal functions of UVRAG, including autophagy, in a dominant-negative manner. Furthermore, expression of UVRAGFS can trigger CRC metastatic spread through Rac1 activation and epithelial-to-mesenchymal transition, independently of autophagy. Interestingly, UVRAGFS expression renders cells more sensitive to standard chemotherapy regimen due to a DNA repair defect. These results identify UVRAG as a new MSI target gene and provide a mechanism for UVRAG participation in CRC pathogenesis and treatment response. PMID:26234763

  6. Autophagy-related Gene 7 (ATG7) and Reactive Oxygen Species/Extracellular Signal-regulated Kinase Regulate Tetrandrine-induced Autophagy in Human Hepatocellular Carcinoma*

    PubMed Central

    Gong, Ke; Chen, Chao; Zhan, Yao; Chen, Yan; Huang, Zebo; Li, Wenhua

    2012-01-01

    Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the broadly used Chinese medicinal herb Stephaniae tetrandrae, exhibits potent antitumor effects and has the potential to be used as a cancer chemotherapeutic agent. We previously reported that high concentrations of tetrandrine induce apoptosis in liver cancer cells. Here, we found that in human hepatocellular carcinoma (HCC) cells, a low dose of tetrandrine (5 μm) induced the expression of LC3-II, resulted in the formation of acidic autophagolysosome vacuoles (AVOs), and caused a punctate fluorescence pattern with the GFP-LC3 protein, which all are markers for cellular autophagy. Tetrandrine induced the production of intracellular reactive oxygen species (ROS), and treatment with ROS scavengers significantly abrogated the tetrandrine-induced autophagy. These results suggest that the generation of ROS plays an important role in promoting tetrandrine-induced autophagy. Tetrandrine-induced mitochondrial dysfunction resulted in ROS accumulation and autophagy. ROS generation activated the ERK MAP kinase, and the ERK signaling pathway at least partially contributed to tetrandrine-induced autophagy in HCC cells. Moreover, we found that tetrandrine transcriptionally regulated the expression of autophagy related gene 7 (ATG7), which promoted tetrandrine-induced autophagy. In addition to in vitro studies, similar results were also observed in vivo, where tetrandrine caused the accumulation of ROS and induced cell autophagy in a tumor xenograft model. Interestingly, tetrandrine treatment also induced autophagy in a ROS-dependent manner in C. elegans muscle cells. Therefore, these findings suggest that tetrandrine is a potent autophagy agonist and may be a promising clinical chemotherapeutic agent. PMID:22927446

  7. Autophagy Constitutes a Protective Mechanism against Ethanol Toxicity in Mouse Astrocytes and Neurons.

    PubMed

    Pla, Antoni; Pascual, María; Guerri, Consuelo

    2016-01-01

    Ethanol induces brain damage and neurodegeneration by triggering inflammatory processes in glial cells through activation of Toll-like receptor 4 (TLR4) signaling. Recent evidence indicates the role of protein degradation pathways in neurodegeneration and alcoholic liver disease, but how these processes affect the brain remains elusive. We have demonstrated that chronic ethanol consumption impairs proteolytic pathways in mouse brain, and the immune response mediated by TLR4 receptors participates in these dysfunctions. We evaluate the in vitro effects of an acute ethanol dose on the autophagy-lysosome pathway (ALP) on WT and TLR4-/- mouse astrocytes and neurons in primary culture, and how these changes affect cell survival. Our results show that ethanol induces overexpression of several autophagy markers (ATG12, LC3-II, CTSB), and increases the number of lysosomes in WT astrocytes, effects accompanied by a basification of lysosomal pH and by lowered phosphorylation levels of autophagy inhibitor mTOR, along with activation of complexes beclin-1 and ULK1. Notably, we found only minor changes between control and ethanol-treated TLR4-/- mouse astroglial cells. Ethanol also triggers the expression of the inflammatory mediators iNOS and COX-2, but induces astroglial death only slightly. Blocking autophagy by using specific inhibitors increases both inflammation and cell death. Conversely, in neurons, ethanol down-regulates the autophagy pathway and triggers cell death, which is partially recovered by using autophagy enhancers. These results support the protective role of the ALP against ethanol-induced astroglial cell damage in a TLR4-dependent manner, and provide new insight into the mechanisms that underlie ethanol-induced brain damage and are neuronal sensitive to the ethanol effects. PMID:27070930

  8. Autophagy Constitutes a Protective Mechanism against Ethanol Toxicity in Mouse Astrocytes and Neurons

    PubMed Central

    Pla, Antoni

    2016-01-01

    Ethanol induces brain damage and neurodegeneration by triggering inflammatory processes in glial cells through activation of Toll-like receptor 4 (TLR4) signaling. Recent evidence indicates the role of protein degradation pathways in neurodegeneration and alcoholic liver disease, but how these processes affect the brain remains elusive. We have demonstrated that chronic ethanol consumption impairs proteolytic pathways in mouse brain, and the immune response mediated by TLR4 receptors participates in these dysfunctions. We evaluate the in vitro effects of an acute ethanol dose on the autophagy-lysosome pathway (ALP) on WT and TLR4-/- mouse astrocytes and neurons in primary culture, and how these changes affect cell survival. Our results show that ethanol induces overexpression of several autophagy markers (ATG12, LC3-II, CTSB), and increases the number of lysosomes in WT astrocytes, effects accompanied by a basification of lysosomal pH and by lowered phosphorylation levels of autophagy inhibitor mTOR, along with activation of complexes beclin-1 and ULK1. Notably, we found only minor changes between control and ethanol-treated TLR4-/- mouse astroglial cells. Ethanol also triggers the expression of the inflammatory mediators iNOS and COX-2, but induces astroglial death only slightly. Blocking autophagy by using specific inhibitors increases both inflammation and cell death. Conversely, in neurons, ethanol down-regulates the autophagy pathway and triggers cell death, which is partially recovered by using autophagy enhancers. These results support the protective role of the ALP against ethanol-induced astroglial cell damage in a TLR4-dependent manner, and provide new insight into the mechanisms that underlie ethanol-induced brain damage and are neuronal sensitive to the ethanol effects. PMID:27070930

  9. Elemene injection induced autophagy protects human hepatoma cancer cells from starvation and undergoing apoptosis.

    PubMed

    Lin, Yan; Wang, Keming; Hu, Chunping; Lin, Lin; Qin, Shukui; Cai, Xueting

    2014-01-01

    Elemene, a compound found in an herb used in traditional Chinese medicine, has shown promising anticancer effects against a broad spectrum of tumors. In an in vivo experiment, we found that apatinib, a tyrosine kinase inhibitor that selectively inhibits VEGFR2, combined with elemene injection (Ele) for the treatment of H22 solid tumor in mice resulted in worse effectiveness than apatinib alone. Moreover, Ele could protect HepG2 cells from death induced by serum-free starvation. Further data on the mechanism study revealed that Ele induced protective autophagy and prevented human hepatoma cancer cells from undergoing apoptosis. Proapoptosis effect of Ele was enhanced when proautophagy effect was inhibited by hydroxychloroquine. Above all, Ele has the effect of protecting cancer cells from death either in apatinib induced nutrient deficient environment or in serum-free induced starvation. A combination of elemene injection with autophagy inhibitor might thus be a useful therapeutic option for hepatocellular carcinoma. PMID:25152762

  10. Global Analysis of Fission Yeast Mating Genes Reveals New Autophagy Factors

    PubMed Central

    Sun, Ling-Ling; Shen, En-Zhi; Yang, Bing; Dong, Meng-Qiu; He, Wan-Zhong; Du, Li-Lin

    2013-01-01

    Macroautophagy (autophagy) is crucial for cell survival during starvation and plays important roles in animal development and human diseases. Molecular understanding of autophagy has mainly come from the budding yeast Saccharomyces cerevisiae, and it remains unclear to what extent the mechanisms are the same in other organisms. Here, through screening the mating phenotype of a genome-wide deletion collection of the fission yeast Schizosaccharomyces pombe, we obtained a comprehensive catalog of autophagy genes in this highly tractable organism, including genes encoding three heretofore unidentified core Atg proteins, Atg10, Atg14, and Atg16, and two novel factors, Ctl1 and Fsc1. We systematically examined the subcellular localization of fission yeast autophagy factors for the first time and characterized the phenotypes of their mutants, thereby uncovering both similarities and differences between the two yeasts. Unlike budding yeast, all three Atg18/WIPI proteins in fission yeast are essential for autophagy, and we found that they play different roles, with Atg18a uniquely required for the targeting of the Atg12–Atg5·Atg16 complex. Our investigation of the two novel factors revealed unforeseen autophagy mechanisms. The choline transporter-like protein Ctl1 interacts with Atg9 and is required for autophagosome formation. The fasciclin domain protein Fsc1 localizes to the vacuole membrane and is required for autophagosome-vacuole fusion but not other vacuolar fusion events. Our study sheds new light on the evolutionary diversity of the autophagy machinery and establishes the fission yeast as a useful model for dissecting the mechanisms of autophagy. PMID:23950735

  11. Protection against Experimental Stroke by Ganglioside GM1 Is Associated with the Inhibition of Autophagy

    PubMed Central

    Li, Li; Tian, Jinghua; Long, Mitchell King-Wei; Chen, Yong; Lu, Jianfei; Zhou, Changman; Wang, Tianlong

    2016-01-01

    Ganglioside GM1, which is particularly abundant in the central nervous system (CNS), is closely associated with the protection against several CNS disorders. However, controversial findings have been reported on the role of GM1 following ischemic stroke. In the present study, using a rat middle cerebral artery occlusion (MCAO) model, we investigated whether GM1 can protect against ischemic brain injury and whether it targets the autophagy pathway. GM1 was delivered to Sprague-Dawley male rats at 3 doses (25 mg/kg, 50 mg/kg, 100 mg/kg) by intraperitoneal injection soon after reperfusion and then once daily for 2 days. The same volume of saline was given as a control. Tat–Beclin-1, a specific autophagy inducer, was administered by intraperitoneal injection at 24 and 48 hours post-MCAO. Infarction volume, mortality and neurological function were assessed at 72 hours after ischemic insult. Immunofluorescence and Western blotting were performed to determine the expression of autophagy-related proteins P62, LC3 and Beclin-1 in the penumbra area. No significant changes in mortality and physiological variables (heart rate, blood glucose levels and arterial blood gases) were observed between the different groups. However, MCAO resulted in enhanced conversion of LC3-I into LC3-II, P62 degradation, high levels of Beclin-1, a large area infarction (26.3±3.6%) and serious neurobehavioral deficits. GM1 (50 mg/kg) treatment significantly reduced the autophagy activation, neurobehavioral dysfunctions, and infarction volume (from 26.3% to 19.5%) without causing significant adverse side effects. However, this biological function could be abolished by Tat–Beclin-1. In conclusion: GM1 demonstrated safe and robust neuroprotective effects that are associated with the inhibition of autophagy following experimental stroke. PMID:26751695

  12. No Evidence for Activated Autophagy in Left Ventricular Myocardium at Early Reperfusion with Protection by Remote Ischemic Preconditioning in Patients Undergoing Coronary Artery Bypass Grafting

    PubMed Central

    Gedik, Nilgün; Thielmann, Matthias; Kottenberg, Eva; Peters, Jürgen; Jakob, Heinz; Heusch, Gerd; Kleinbongard, Petra

    2014-01-01

    Objective Remote ischemic preconditioning (RIPC) by repeated brief limb ischemia/reperfusion reduces myocardial injury in patients undergoing coronary artery bypass grafting (CABG). Activation of signal transducer and activator of transcription 5 (STAT5) in left ventricular (LV) myocardium at early reperfusion is associated with such protection. Autophagy, i.e., removal of dysfunctional cellular components through lysosomes, has been proposed as one mechanism of cardioprotection. Therefore, we analyzed whether or not the protection by RIPC is associated with activated autophagy. Methods CABG patients were randomized to undergo RIPC (3×5 min blood pressure cuff inflation/5 min deflation) or placebo (cuff deflated) before skin incision (n = 10/10). Transmural myocardial biopsies were taken from the LV before cardioplegia (baseline) and at early (5–10 min) reperfusion. RIPC-induced protection was reflected by decreased serum troponin I concentration area under the curve (194±17 versus 709±129 ng/ml × 72 h, p = 0.002). Western blotting for beclin-1-phosphorylation and protein expression of autophagy-related gene 5–12 (ATG5-12) complex, light chain 3 (LC3), parkin, and p62 was performed. STAT3-, STAT5- and extracellular signal-regulated protein kinase 1/2 (ERK1/2)-phosphorylation was used as positive control to confirm signal activation by ischemia/reperfusion. Results Signals of all analyzed autophagy proteins did not differ between baseline and early reperfusion and not between RIPC and placebo. STAT5-phosphorylation was greater at early reperfusion only with RIPC (2.2-fold, p = 0.02). STAT3- and ERK1/2-phosphorylation were greater at early reperfusion with placebo and RIPC (≥2.7-fold versus baseline, p≤0.05). Conclusion Protection through RIPC in patients undergoing CABG surgery does not appear to be associated with enhanced autophagy in LV myocardium at early reperfusion. PMID:24797938

  13. Autophagy protects type II alveolar epithelial cells from Mycobacterium tuberculosis infection

    SciTech Connect

    Guo, Xu-Guang; Ji, Tian-Xing; Xia, Yong; Ma, Yue-Yun

    2013-03-08

    Highlights: ► We investigated the protective effect of autophagy pathway against MTB infection. ► MTB-infected A549 cells had higher LDH release. ► Inhibition of autophagy signaling significantly enhanced the MTB-induced necrosis. ► Autophagy prevents apoptosis and promotes cell survival in infected cells. -- Abstract: This study was designed to investigate the protective effect of the autophagy signaling pathway against Mycobacterium tuberculosis infection in type II alveolar epithelial cells. An in vitro M. tuberculosis system was established using human A549 cells. Infection-induced changes in the expression of the autophagic marker LC3 were assessed by reverse transcription-PCR and Western blotting. Morphological changes in autophagosomes were detected by transmission electron microscopy (TEM). The function of the autophagy signaling pathway during infection was assessed by measuring the level of cell death and the amount of lactate dehydrogenase (LDH) released in the presence or absence of the inhibitor 3-methyladenine (3-MA). In addition, effects on LDH release were assessed after the siRNA-mediated knockdown of the essential autophagosomal structural membrane protein Atg5. LC3 mRNA expression was significantly reduced in M.tuberculosis-infected A549 cells (16888.76 ± 1576.34 vs. uninfected: 12744.29 ± 1089.37; P < 0.05). TEM revealed M.tuberculosis bacilli-containing compartments that were surrounded by double membranes characteristic of the autophagic process. M.tuberculosis-infected A549 cells released more LDH (1.45 ± 0.12 vs. uninfected: 0.45 ± 0.04; P < 0.05). The inhibition of autophagy signaling significantly enhanced M.tuberculosis-induced necrosis (3-MA: 75 ± 5% vs. untreated: 15 ± 1%; P < 0.05) and LDH release (3-MA: 2.50 ± 0.24 vs. untreated: 0.45 ± 0.04; Atg5 knockdown: 3.19 ± 0.29 vs. untreated: 1.28 ± 0.11; P < 0.05). Our results indicate that autophagy signaling pathway prevents apoptosis in type II alveolar epithelial cells

  14. Hydrogen sulfide lowers proliferation and induces protective autophagy in colon epithelial cells.

    PubMed

    Wu, Ya C; Wang, Xiao J; Yu, Le; Chan, Francis K L; Cheng, Alfred S L; Yu, Jun; Sung, Joseph J Y; Wu, William K K; Cho, Chi H

    2012-01-01

    Hydrogen sulfide (H(2)S) is a gaseous bacterial metabolite that reaches high levels in the large intestine. In the present study, the effect of H(2)S on the proliferation of normal and cancerous colon epithelial cells was investigated. An immortalized colon epithelial cell line (YAMC) and a panel of colon cancer cell lines (HT-29, SW1116, HCT116) were exposed to H(2)S at concentrations similar to those found in the human colon. H(2)S inhibited normal and cancerous colon epithelial cell proliferation as measured by MTT assay. The anti-mitogenic effect of H(2)S was accompanied by G(1)-phase cell cycle arrest and the induction of the cyclin-dependent kinase inhibitor p21(Cip). Moreover, exposure to H(2)S led to features characteristic of autophagy, including increased formation of LC3B(+) autophagic vacuoles and acidic vesicular organelles as determined by immunofluorescence and acridine orange staining, respectively. Abolition of autophagy by RNA interference targeting Vps34 or Atg7 enhanced the anti-proliferative effect of H(2)S. Further mechanistic investigation revealed that H(2)S stimulated the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and S6 kinase. Inhibition of AMPK significantly reversed H(2)S-induced autophagy and inhibition of cell proliferation. Collectively, we demonstrate that H(2)S inhibits colon epithelial cell proliferation and induces protective autophagy via the AMPK pathway. PMID:22679478

  15. Endothelial cell and podocyte autophagy synergistically protect from diabetes-induced glomerulosclerosis.

    PubMed

    Lenoir, Olivia; Jasiek, Magali; Hénique, Carole; Guyonnet, Léa; Hartleben, Björn; Bork, Tillmann; Chipont, Anna; Flosseau, Kathleen; Bensaada, Imane; Schmitt, Alain; Massé, Jean-Marc; Souyri, Michèle; Huber, Tobias B; Tharaux, Pierre-Louis

    2015-01-01

    The glomerulus is a highly specialized capillary tuft, which under pressure filters large amounts of water and small solutes into the urinary space, while retaining albumin and large proteins. The glomerular filtration barrier (GFB) is a highly specialized filtration interface between blood and urine that is highly permeable to small and midsized solutes in plasma but relatively impermeable to macromolecules such as albumin. The integrity of the GFB is maintained by molecular interplay between its 3 layers: the glomerular endothelium, the glomerular basement membrane and podocytes, which are highly specialized postmitotic pericytes forming the outer part of the GFB. Abnormalities of glomerular ultrafiltration lead to the loss of proteins in urine and progressive renal insufficiency, underlining the importance of the GFB. Indeed, albuminuria is strongly predictive of the course of chronic nephropathies especially that of diabetic nephropathy (DN), a leading cause of renal insufficiency. We found that high glucose concentrations promote autophagy flux in podocyte cultures and that the abundance of LC3B II in podocytes is high in diabetic mice. Deletion of Atg5 specifically in podocytes resulted in accelerated diabetes-induced podocytopathy with a leaky GFB and glomerulosclerosis. Strikingly, genetic alteration of autophagy on the other side of the GFB involving the endothelial-specific deletion of Atg5 also resulted in capillary rarefaction and accelerated DN. Thus autophagy is a key protective mechanism on both cellular layers of the GFB suggesting autophagy as a promising new therapeutic strategy for DN. PMID:26039325

  16. Digesting the Genetics of Inflammatory Bowel Disease – Insights from Studies of Autophagy Risk Genes

    PubMed Central

    Kabi, Amrita; Nickerson, Kourtney P.; Homer, Craig R.; McDonald, Christine

    2011-01-01

    The success of genetic analyses identifying multiple loci associated with IBD susceptibility has resulted in the identification of several risk genes linked to a common cellular process called autophagy. Autophagy is a process involving the encapsulation of cytosolic cellular components in double membraned vesicles, their subsequent lysosomal degradation, and recycling of the degraded components for use by the cell. It plays an important part in the innate immune response to a variety of intracellular pathogens, and it is this component of autophagy that appears to be defective in IBD. This has lead to the hypothesis that CD may result from an impaired anti-bacterial response, which leads to ineffective control of bacterial infection, dysbiosis of the intestinal microbiota, and chronic inflammation. Several recurrent themes have surfaced from studies examining the function of autophagy-related genes in the context of IBD - with cellular context, disease status, risk variant effect and risk gene interplay all affecting the interpretation of these studies. The identification of autophagy as a major risk pathway in IBD is a significant step forward and may lead to pathway-focused therapy in the future, however there is more to understand in order to unravel the complexity of this disease. PMID:21936032

  17. New horizons in schizophrenia treatment: autophagy protection is coupled with behavioral improvements in a mouse model of schizophrenia

    PubMed Central

    Merenlender-Wagner, Avia; Shemer, Zeev; Touloumi, Olga; Lagoudaki, Roza; Giladi, Eliezer; Andrieux, Annie; Grigoriadis, Nikolaos C; Gozes, Illana

    2015-01-01

    Autophagy plays a key role in the pathophysiology of schizophrenia as manifested by a 40% decrease in BECN1/Beclin 1 mRNA in postmortem hippocampal tissues relative to controls. This decrease was coupled with the deregulation of the essential ADNP (activity-dependent neuroprotector homeobox), a binding partner of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β) another major constituent of autophagy. The drug candidate NAP (davunetide), a peptide fragment from ADNP, enhanced the ADNP-LC3B interaction. Parallel genetic studies have linked allelic variation in the gene encoding MAP6/STOP (microtubule-associated protein 6) to schizophrenia, along with altered MAP6/STOP protein expression in the schizophrenic brain and schizophrenic-like behaviors in Map6-deficient mice. In this study, for the first time, we reveal significant decreases in hippocampal Becn1 mRNA and reversal by NAP but not by the antipsychotic clozapine (CLZ) in Map6-deficient (Map6+/−) mice. Normalization of Becn1 expression by NAP was coupled with behavioral protection against hyperlocomotion and cognitive deficits measured in the object recognition test. CLZ reduced hyperlocomotion below control levels and did not significantly affect object recognition. The combination of CLZ and NAP resulted in normalized outcome behaviors. Phase II clinical studies have shown NAP-dependent augmentation of functional activities of daily living coupled with brain protection. The current studies provide a new mechanistic pathway and a novel avenue for drug development. PMID:25484074

  18. New horizons in schizophrenia treatment: autophagy protection is coupled with behavioral improvements in a mouse model of schizophrenia.

    PubMed

    Merenlender-Wagner, Avia; Shemer, Zeev; Touloumi, Olga; Lagoudaki, Roza; Giladi, Eliezer; Andrieux, Annie; Grigoriadis, Nikolaos C; Gozes, Illana

    2014-01-01

    Autophagy plays a key role in the pathophysiology of schizophrenia as manifested by a 40% decrease in BECN1/Beclin 1 mRNA in postmortem hippocampal tissues relative to controls. This decrease was coupled with the deregulation of the essential ADNP (activity-dependent neuroprotector homeobox), a binding partner of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β) another major constituent of autophagy. The drug candidate NAP (davunetide), a peptide fragment from ADNP, enhanced the ADNP-LC3B interaction. Parallel genetic studies have linked allelic variation in the gene encoding MAP6/STOP (microtubule-associated protein 6) to schizophrenia, along with altered MAP6/STOP protein expression in the schizophrenic brain and schizophrenic-like behaviors in Map6-deficient mice. In this study, for the first time, we reveal significant decreases in hippocampal Becn1 mRNA and reversal by NAP but not by the antipsychotic clozapine (CLZ) in Map6-deficient (Map6(+/-)) mice. Normalization of Becn1 expression by NAP was coupled with behavioral protection against hyperlocomotion and cognitive deficits measured in the object recognition test. CLZ reduced hyperlocomotion below control levels and did not significantly affect object recognition. The combination of CLZ and NAP resulted in normalized outcome behaviors. Phase II clinical studies have shown NAP-dependent augmentation of functional activities of daily living coupled with brain protection. The current studies provide a new mechanistic pathway and a novel avenue for drug development. PMID:25484074

  19. Triptolide induces protective autophagy through activation of the CaMKKβ-AMPK signaling pathway in prostate cancer cells

    PubMed Central

    Zhang, Zhe; Mao, Lin; Han, Yangyang; Yan, Jun; Lei, Ming

    2016-01-01

    Triptolide, an active compound extracted from the Chinese herb thunder god vine (Tripterygium wilfordii Hook F.), has potent anti-tumor activity. Recently, triptolide was found to induce autophagy in cancer cells. However, the effects of triptolide on autophagy in human prostate cancer (PCa) cells have not yet been clearly elucidated. In this study, we demonstrated that triptolide induces autophagy in three PCa cell lines, PC-3, LNCaP and C4–2. Furthermore, we found that triptolide mediates intracellular accumulation of free calcium by stimulating the endoplasmic reticulum (ER) stress response. This activates the CaMKKβ-AMPK signaling pathway, which in turn inhibits mTOR and activates both ULK1 and Beclin 1, finally resulting in autophagy. Moreover, we found that treatment with autophagy inhibitors 3-methyladenine (3-MA) and chloroquine (CQ) enhances triptolide-induced PCa cell death and growth inhibition. Using a PC-3-xenografted mouse model, we showed that blocking autophagy with CQ significantly promoted triptolide-induced tumor growth inhibition in vivo. Overall, our results show that triptolide induces protective autophagy through the CaMKKβ-AMPK pathway in PCa cells, implying that a combination of triptolide with autophagy inhibitors may potentially be an effective therapeutic strategy for PCa. PMID:26734992

  20. Autophagy Is a Protective Mechanism for Human Melanoma Cells under Acidic Stress*

    PubMed Central

    Marino, Maria Lucia; Pellegrini, Paola; Di Lernia, Giuseppe; Djavaheri-Mergny, Mojgan; Brnjic, Slavica; Zhang, Xiaonan; Hägg, Maria; Linder, Stig; Fais, Stefano; Codogno, Patrice; De Milito, Angelo

    2012-01-01

    Cyclic hypoxia and alterations in oncogenic signaling contribute to switch cancer cell metabolism from oxidative phosphorylation to aerobic glycolysis. A major consequence of up-regulated glycolysis is the increased production of metabolic acids responsible for the presence of acidic areas within solid tumors. Tumor acidosis is an important determinant of tumor progression and tumor pH regulation is being investigated as a therapeutic target. Autophagy is a cellular catabolic pathway leading to lysosomal degradation and recycling of proteins and organelles, currently considered an important survival mechanism in cancer cells under metabolic stress or subjected to chemotherapy. We investigated the response of human melanoma cells cultured in acidic conditions in terms of survival and autophagy regulation. Melanoma cells exposed to acidic culture conditions (7.0 < pH < 6.2) promptly accumulated LC3+ autophagic vesicles. Immunoblot analysis showed a consistent increase of LC3-II in acidic culture conditions as compared with cells at normal pH. Inhibition of lysosomal acidification by bafilomycin A1 further increased LC3-II accumulation, suggesting an active autophagic flux in cells under acidic stress. Acute exposure to acidic stress induced rapid inhibition of the mammalian target of rapamycin signaling pathway detected by decreased phosphorylation of p70S6K and increased phosphorylation of AMP-activated protein kinase, associated with decreased ATP content and reduced glucose and leucine uptake. Inhibition of autophagy by knockdown of the autophagic gene ATG5 consistently reduced melanoma cell survival in low pH conditions. These observations indicate that induction of autophagy may represent an adaptation mechanism for cancer cells exposed to an acidic environment. Our data strengthen the validity of therapeutic strategies targeting tumor pH regulation and autophagy in progressive malignancies. PMID:22761435

  1. The autophagy gene Atg16l1 differentially regulates Treg and TH2 cells to control intestinal inflammation.

    PubMed

    Kabat, Agnieszka M; Harrison, Oliver J; Riffelmacher, Thomas; Moghaddam, Amin E; Pearson, Claire F; Laing, Adam; Abeler-Dörner, Lucie; Forman, Simon P; Grencis, Richard K; Sattentau, Quentin; Simon, Anna Katharina; Pott, Johanna; Maloy, Kevin J

    2016-01-01

    A polymorphism in the autophagy gene Atg16l1 is associated with susceptibility to inflammatory bowel disease (IBD); however, it remains unclear how autophagy contributes to intestinal immune homeostasis. Here, we demonstrate that autophagy is essential for maintenance of balanced CD4(+) T cell responses in the intestine. Selective deletion of Atg16l1 in T cells in mice resulted in spontaneous intestinal inflammation that was characterized by aberrant type 2 responses to dietary and microbiota antigens, and by a loss of Foxp3(+) Treg cells. Specific ablation of Atg16l1 in Foxp3(+) Treg cells in mice demonstrated that autophagy directly promotes their survival and metabolic adaptation in the intestine. Moreover, we also identify an unexpected role for autophagy in directly limiting mucosal TH2 cell expansion. These findings provide new insights into the reciprocal control of distinct intestinal TH cell responses by autophagy, with important implications for understanding and treatment of chronic inflammatory disorders. PMID:26910010

  2. Dengue-induced autophagy, virus replication and protection from cell death require ER stress (PERK) pathway activation

    PubMed Central

    Datan, E; Roy, S G; Germain, G; Zali, N; McLean, J E; Golshan, G; Harbajan, S; Lockshin, R A; Zakeri, Z

    2016-01-01

    A virus that reproduces in a host without killing cells can easily establish a successful infection. Previously, we showed that dengue-2, a virus that threatens 40% of the world, induces autophagy, enabling dengue to reproduce in cells without triggering cell death. Autophagy further protects the virus-laden cells from further insults. In this study, we evaluate how it does so; we show that dengue upregulates host pathways that increase autophagy, namely endoplasmic reticulum (ER) stress and ataxia telangiectasia mutated (ATM) signaling followed by production of reactive oxygen species (ROS). Inhibition of ER stress or ATM signaling abrogates the dengue-conferred protection against other cell stressors. Direct inhibition of ER stress response in infected cells decreases autophagosome turnover, reduces ROS production and limits reproduction of dengue virus. Blocking ATM activation, which is an early response to infection, decreases transcription of ER stress response proteins, but ATM has limited impact on production of ROS and virus titers. Production of ROS determines only late-onset autophagy in infected cells and is not necessary for dengue-induced protection from stressors. Collectively, these results demonstrate that among the multiple autophagy-inducing pathways during infection, ER stress signaling is more important to viral replication and protection of cells than either ATM or ROS-mediated signaling. To limit virus production and survival of dengue-infected cells, one must address the earliest phase of autophagy, induced by ER stress. PMID:26938301

  3. Identification of autophagy genes participating in zinc-induced necrotic cell death in Saccharomyces cerevisiae

    PubMed Central

    Dziedzic, Slawomir A

    2011-01-01

    Eukaryotes use a common set of genes to perform two mechanistically similar autophagic processes. Bulk autophagy harvests proteins nonselectively and reuses their constitutents when nutrients are scarce. In contrast, different forms of selective autophagy target protein aggregates or damaged organelles that threaten to interfere with growth. Yeast uses one form of selective autophagy, called cytoplasm-to-vacuole targeting (Cvt), to engulf two vacuolar enzymes in Cvt vesicles (“CVT-somes”) within which they are transported to vacuoles for maturation. While both are dispensable normally, bulk and selective autophagy help sustain life under stressful conditions. Consistent with this view, knocking out several genes participating in Cvt and specialized autophagic pathways heightened the sensitivity of Saccharomyces cerevisiae to inhibitory levels of Zn2+. The loss of other autophagic genes, and genes responsible for apoptotic cell death, had no such effect. Unexpectedly, the loss of members of a third set of autophagy genes heightened cellular resistance to zinc as if they encoded proteins that actively contributed to zinc-induced cell death. Further studies showed that both sensitive and resistant strains accumulated similar amounts of H2O2 during zinc treatments, but that more sensitive strains showed signs of necrosis sooner. Although zinc lethality depended on autophagic proteins, studies with several reporter genes failed to reveal increased autophagic activity. In fact, microscopy analysis indicated that Zn2+ partially inhibited fusion of Cvt vesicles with vacuoles. Further studies into how the loss of autophagic processes suppressed necrosis in yeast might reveal whether a similar process could occur in plants and animals. PMID:21317551

  4. Regulation of autophagy by two products of one gene: TRPM3 and miR-204

    PubMed Central

    Cost, Nicolas G; Czyzyk-Krzeska, Maria F

    2015-01-01

    In clear cell renal cell carcinoma (ccRCC), oncogenic autophagy dependent on microtubule-associated protein 1 light chain 3 α and β (LC3A and LC3B) is stimulated by activity of the transient receptor potential melastatin 3 (TRPM3) channel through multiple complementary mechanisms. The Von Hippel-Lindau (VHL) tumor suppressor represses this oncogenic autophagy in a coordinated manner through the activity of miR-204, which is expressed from intron 6 of the gene encoding TRPM3. TRPM3 represents an actionable target for ccRCC treatment. PMID:27308495

  5. A SIRT3/AMPK/autophagy network orchestrates the protective effects of trans-resveratrol in stressed peritoneal macrophages and RAW 264.7 macrophages.

    PubMed

    Duan, Wen-Jun; Li, Yi-Fang; Liu, Fang-Lan; Deng, Jie; Wu, Yan-Ping; Yuan, Wei-Lin; Tsoi, Bun; Chen, Jun-Li; Wang, Qi; Cai, Shao-Hui; Kurihara, Hiroshi; He, Rong-Rong

    2016-06-01

    Resveratrol gains a great interest for its strong antioxidant properties, while the molecular mechanisms underlie the beneficial effects on psychosocial stress remain controversial. In this study, we demonstrated that resveratrol protected peritoneal macrophages and RAW 264.7 cells from stress-induced decrease in the total cell count, phagocytic capability, reactive oxygen species generation, monodansylcadaverine and mitochondrial membrane potential in stressed mice. Resveratrol promoted stress-induced autophagy in both models. Modulation of autophagy by rapamycin or 3-methyladenine regulated the protective effect of resveratrol, suggesting a role of autophagy in the protective mechanisms of resveratrol. The comparison studies revealed that distinct mechanisms were implicated in the protective effect of resveratrol and other antioxidants (vitamin C and edaravone). Resveratrol promoted autophagy via upregulating SIRT3 expression and phosphorylation of AMP-activated protein kinase (AMPK). Knockdown of SIRT3 resulted in decreased autophagy and abolished protective effect of resveratrol. SIRT1 was also involved in the protective mechanism of resveratrol, although its effect on autophagy was unnoticeable. Pharmacological manipulation of autophagy modulated the effects of resveratrol on SIRT3 and AMPK, revealing the engagement of a positive feedback loop. In sharp contrast, vitamin C and edaravone effectively protected macrophages from stress-induced cytotoxicity, accompanied by downregulated SIRT3 expression and AMPK phosphorylation, and decreased level of autophagy response. Taken together, we conclude that a SIRT3/AMPK/autophagy network orchestrates in the protective effect of resveratrol in macrophages. PMID:27021965

  6. Remifentanil Protects Human Keratinocytes against Hypoxia–Reoxygenation Injury through Activation of Autophagy

    PubMed Central

    Kwon, Jae-Young; Park, Bong-Soo; Kim, Yong-Ho; Kim, Yong-Deok; Kim, Cheul- Hong; Yoon, Ji-Young; Yoon, Ji-Uk

    2015-01-01

    The proliferation, differentiation, and migration of keratinocytes are essential in the early stages of wound healing. Hypoxia-Reoxygenation (H/R) injury to keratinocytes can occur in various stressful environments such as surgery, trauma, and various forms of ulcers. The effects of remifentanil on human keratinocytes under hypoxia-reoxygenation have not been fully studied. Therefore, we investigated the effects of remifentanil on the proliferation, apoptosis, and autophagic activation of human keratinocytes during hypoxic-reoxygenation. Human keratinocytes were cultured under 1% oxygen tension for 24 h. The cells were then treated with various concentrations of remifentanil (0.01, 0.1, 0.5, and 1 ng/mL) for 2 h. Thereafter, the cells were reoxygenated for 12 h at 37°C. We measured cell viability via MTT assay. Using quantitative real-time PCR and western blot analysis, we measured the expression levels of proteins associated with apoptosis and autophagy. Quantification of apoptotic cells was performed using flow cytometer analysis and autophagic vacuoles were observed under a fluorescence microscope. Remifentanil treatment brought about an increase in the proliferation of human keratinocytes damaged by hypoxia-reoxygenation and decreased the apoptotic cell death, enhancing autophagic activity. However, the autophagy pathway inhibitor 3-MA inhibited the protective effect of remifentanil in hypoxia-reoxygenation injury. In conclusion, the current study demonstrated that remifentanil treatment stimulated autophagy and reduced apoptotic cell death in a hypoxia-reoxygenation model of human keratinocytes. Our results provide additional insights into the relationship between apoptosis and autophagy. PMID:25615605

  7. Activation of RARα induces autophagy in SKBR3 breast cancer cells and depletion of key autophagy genes enhances ATRA toxicity.

    PubMed

    Brigger, D; Schläfli, A M; Garattini, E; Tschan, M P

    2015-01-01

    All-trans retinoic acid (ATRA), a pan-retinoic acid receptor (RAR) agonist, is, along with other retinoids, a promising therapeutic agent for the treatment of a variety of solid tumors. On the one hand, preclinical studies have shown promising anticancer effects of ATRA in breast cancer; on the other hand, resistances occurred. Autophagy is a cellular recycling process that allows the degradation of bulk cellular contents. Tumor cells may take advantage of autophagy to cope with stress caused by anticancer drugs. We therefore wondered if autophagy is activated by ATRA in mammary tumor cells and if modulation of autophagy might be a potential novel treatment strategy. Indeed, ATRA induces autophagic flux in ATRA-sensitive but not in ATRA-resistant human breast cancer cells. Moreover, using different RAR agonists as well as RARα-knockdown breast cancer cells, we demonstrate that autophagy is dependent on RARα activation. Interestingly, inhibition of autophagy in breast cancer cells by either genetic or pharmacological approaches resulted in significantly increased apoptosis under ATRA treatment and attenuated epithelial differentiation. In summary, our findings demonstrate that ATRA-induced autophagy is mediated by RARα in breast cancer cells. Furthermore, inhibition of autophagy results in enhanced apoptosis. This points to a potential novel treatment strategy for a selected group of breast cancer patients where ATRA and autophagy inhibitors are applied simultaneously. PMID:26313912

  8. Activation of RARα induces autophagy in SKBR3 breast cancer cells and depletion of key autophagy genes enhances ATRA toxicity

    PubMed Central

    Brigger, D; Schläfli, A M; Garattini, E; Tschan, M P

    2015-01-01

    All-trans retinoic acid (ATRA), a pan-retinoic acid receptor (RAR) agonist, is, along with other retinoids, a promising therapeutic agent for the treatment of a variety of solid tumors. On the one hand, preclinical studies have shown promising anticancer effects of ATRA in breast cancer; on the other hand, resistances occurred. Autophagy is a cellular recycling process that allows the degradation of bulk cellular contents. Tumor cells may take advantage of autophagy to cope with stress caused by anticancer drugs. We therefore wondered if autophagy is activated by ATRA in mammary tumor cells and if modulation of autophagy might be a potential novel treatment strategy. Indeed, ATRA induces autophagic flux in ATRA-sensitive but not in ATRA-resistant human breast cancer cells. Moreover, using different RAR agonists as well as RARα-knockdown breast cancer cells, we demonstrate that autophagy is dependent on RARα activation. Interestingly, inhibition of autophagy in breast cancer cells by either genetic or pharmacological approaches resulted in significantly increased apoptosis under ATRA treatment and attenuated epithelial differentiation. In summary, our findings demonstrate that ATRA-induced autophagy is mediated by RARα in breast cancer cells. Furthermore, inhibition of autophagy results in enhanced apoptosis. This points to a potential novel treatment strategy for a selected group of breast cancer patients where ATRA and autophagy inhibitors are applied simultaneously. PMID:26313912

  9. Preconditioning of endoplasmic reticulum stress protects against acrylonitrile-induced cytotoxicity in primary rat astrocytes: The role of autophagy.

    PubMed

    Yu, Bai; Wenjun, Zhao; Changsheng, Yin; Yuntao, Fang; Jing, Ma; Ben, Li; Hai, Qian; Guangwei, Xing; Suhua, Wang; Fang, Li; Aschner, Michael; Rongzhu, Lu

    2016-07-01

    This study explored the protective effects of endoplasmic reticulum (ER) stress preconditioning induced by 2-deoxy-d-glucose (2-DG) or oxidized dithiothreitol (DTTox) on acrylonitrile (AN)-induced cytotocity in primary rat astrocytes. Cells were pretreated with 2-DG or DTTox for different times at various concentration. Next, astrocytes were treated with 2.5mM AN for an additional 12h. Cell viability and cytotoxicity were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and lactate dehydrogenase (LDH) leakage, respectively. Reactive oxygen species (ROS) and mitochondrial membrane potential (ΔΨm) were determined. Expression of glucose-regulated protein 78 (GRP78), phosphorylated-eukaryotic translation initiation factor 2α (p-eIF2α), microtubule-associated protein light chain 3 (LC3), P62, and Beclin1 were used to assess autophagy. In addition, 3-methyadenine (3-MA), an autophagy-specific inhibitor, was used to assess the role of autophagy in ER stress preconditioning-induced protection against AN cytotoxicity. The results showed that AN alone significantly decreased astrocytic viability and enhanced cytotoxicity. Compared to the AN-alone group, preconditioning with 2-DG or DTTox significantly increased cell viability and reduced cytotoxicity to indistinguishable levels. Decreased ROS generation and increased ΔΨm were also inherent to ER stress preconditioning with these compounds. Furthermore, autophagy was activated by both 2-DG and DTTox. Blockage of autophagy attenuated the protection afforded by 2-DG or DTTox preconditioning in AN-treated astrocytes. These results establish that ER stress preconditioning affords cellular protection against AN, and that activation of autophagy mediates the cytoprotection. Modulation of ER stress and resultant activation of autophagy may be a novel target for to ameliorate AN toxicity. PMID:27260289

  10. A comprehensive, genome-wide analysis of autophagy-related genes identified in tobacco suggests a central role of autophagy in plant response to various environmental cues.

    PubMed

    Zhou, Xue-mei; Zhao, Peng; Wang, Wei; Zou, Jie; Cheng, Tian-he; Peng, Xiong-bo; Sun, Meng-xiang

    2015-08-01

    Autophagy is an evolutionarily conserved mechanism in both animals and plants, which has been shown to be involved in various essential developmental processes in plants. Nicotiana tabacum is considered to be an ideal model plant and has been widely used for the study of the roles of autophagy in the processes of plant development and in the response to various stresses. However, only a few autophagy-related genes (ATGs) have been identified in tobacco up to now. Here, we identified 30 ATGs belonging to 16 different groups in tobacco through a genome-wide survey. Comprehensive expression profile analysis reveals an abroad expression pattern of these ATGs, which could be detected in all tissues tested under normal growth conditions. Our series tests further reveal that majority of ATGs are sensitive and responsive to different stresses including nutrient starvation, plant hormones, heavy metal and other abiotic stresses, suggesting a central role of autophagy, likely as an effector, in plant response to various environmental cues. This work offers a detailed survey of all ATGs in tobacco and also suggests manifold functions of autophagy in both normal plant growth and plant response to environmental stresses. PMID:26205094

  11. A comprehensive, genome-wide analysis of autophagy-related genes identified in tobacco suggests a central role of autophagy in plant response to various environmental cues

    PubMed Central

    Zhou, Xue-mei; Zhao, Peng; Wang, Wei; Zou, Jie; Cheng, Tian-he; Peng, Xiong-bo; Sun, Meng-xiang

    2015-01-01

    Autophagy is an evolutionarily conserved mechanism in both animals and plants, which has been shown to be involved in various essential developmental processes in plants. Nicotiana tabacum is considered to be an ideal model plant and has been widely used for the study of the roles of autophagy in the processes of plant development and in the response to various stresses. However, only a few autophagy-related genes (ATGs) have been identified in tobacco up to now. Here, we identified 30 ATGs belonging to 16 different groups in tobacco through a genome-wide survey. Comprehensive expression profile analysis reveals an abroad expression pattern of these ATGs, which could be detected in all tissues tested under normal growth conditions. Our series tests further reveal that majority of ATGs are sensitive and responsive to different stresses including nutrient starvation, plant hormones, heavy metal and other abiotic stresses, suggesting a central role of autophagy, likely as an effector, in plant response to various environmental cues. This work offers a detailed survey of all ATGs in tobacco and also suggests manifold functions of autophagy in both normal plant growth and plant response to environmental stresses. PMID:26205094

  12. The Autoimmunity-Associated Gene CLEC16A Modulates Thymic Epithelial Cell Autophagy and Alters T Cell Selection.

    PubMed

    Schuster, Cornelia; Gerold, Kay D; Schober, Kilian; Probst, Lilli; Boerner, Kevin; Kim, Mi-Jeong; Ruckdeschel, Anna; Serwold, Thomas; Kissler, Stephan

    2015-05-19

    CLEC16A variation has been associated with multiple immune-mediated diseases, including type 1 diabetes, multiple sclerosis, systemic lupus erythematosus, celiac disease, Crohn's disease, Addison's disease, primary biliary cirrhosis, rheumatoid arthritis, juvenile idiopathic arthritis, and alopecia areata. Despite strong genetic evidence implicating CLEC16A in autoimmunity, this gene's broad association with disease remains unexplained. We generated Clec16a knock-down (KD) mice in the nonobese diabetic (NOD) model for type 1 diabetes and found that Clec16a silencing protected against autoimmunity. Disease protection was attributable to T cell hyporeactivity, which was secondary to changes in thymic epithelial cell (TEC) stimuli that drive thymocyte selection. Our data indicate that T cell selection and reactivity were impacted by Clec16a variation in thymic epithelium owing to Clec16a's role in TEC autophagy. These findings provide a functional link between human CLEC16A variation and the immune dysregulation that underlies the risk of autoimmunity. PMID:25979422

  13. ZNF32 inhibits autophagy through the mTOR pathway and protects MCF-7 cells from stimulus-induced cell death

    PubMed Central

    Li, Yanyan; Zhang, Le; Li, Kai; Li, Jun; Xiang, Rong; Zhang, Jie; Li, Hongjiang; Xu, Yan; Wei, Yuyan; Gao, Junping; Lin, Ping; Wei, Yuquan

    2015-01-01

    ZNF32 is a recently identified zinc finger protein and its functions remain largely unknown. Autophagy has been shown to affect cell proliferation and survival. Here, we innovatively show the effect of ZNF32 on cell autophagy and autophagy-associated cell death in breast carcinoma cells and also elucidate its underlying mechanisms. We examined the autophagic activity and LC3 II expression in human carcinoma cell lines with increased or decreased ZNF32 expression. Pharmacological inhibition (rapamycin) or activation (EGF) assays were used to investigate the function of the AKT/mTOR pathway during this process. H2O2- and diamide-induced MCF-7 cell death models were used to elucidate the role of ZNF32-associated autophagy in breast carcinoma cell death. Our results show that increasing ZNF32 expression in MCF-7 cells inhibits autophagy initiation by activating the AKT/mTOR pathway, and further reduced autophagy-associated cell death and maintained MCF-7 cell survival. Conversely, impairing ZNF32 expression by transfecting ZNF32 siRNA strongly promoted autophagy, further augmenting autophagy-associated cell death. Furthermore, correlations between ZNF32 and autophagy were observed in both MCF-7 xenograft tumors and in breast cancer patients. In conclusion, ZNF32 acts as an effective autophagy inhibitor to protect breast cancer cells from excessive stimulus-autophagy-induced cell death. PMID:25786368

  14. Autophagy Protects Against Aminochrome-Induced Cell Death in Substantia Nigra-Derived Cell Line

    PubMed Central

    Paris, Irmgard; Muñoz, Patricia; Huenchuguala, Sandro; Couve, Eduardo; Sanders, Laurie H.; Greenamyre, John Timothy; Caviedes, Pablo; Segura-Aguilar, Juan

    2011-01-01

    Aminochrome, the precursor of neuromelanin, has been proposed to be involved in the neurodegeneration neuromelanin-containing dopaminergic neurons in Parkinson’s disease. We aimed to study the mechanism of aminochrome-dependent cell death in a cell line derived from rat substantia nigra. We found that aminochrome (50μM), in the presence of NAD(P)H-quinone oxidoreductase, EC 1.6.99.2 (DT)-diaphorase inhibitor dicoumarol (DIC) (100μM), induces significant cell death (62 ± 3%; p < 0.01), increase in caspase-3 activation (p < 0.001), release of cytochrome C, disruption of mitochondrial membrane potential (p < 0.01), damage of mitochondrial DNA, damage of mitochondria determined with transmission electron microscopy, a dramatic morphological change characterized as cell shrinkage, and significant increase in number of autophagic vacuoles. To determine the role of autophagy on aminochrome-induced cell death, we incubated the cells in the presence of vinblastine and rapamycin. Interestingly, 10μM vinblastine induces a 5.9-fold (p < 0.001) and twofold (p < 0.01) significant increase in cell death when the cells were incubated with 30μM aminochrome in the absence and presence of DIC, respectively, whereas 10μM rapamycin preincubated 24 h before addition of 50μM aminochrome in the absence and the presence of 100μM DIC induces a significant decrease (p < 0.001) in cell death. In conclusion, autophagy seems to be an important protective mechanism against two different aminochrome-induced cell deaths that initially showed apoptotic features. The cell death induced by aminochrome when DT-diaphorase is inhibited requires activation of mitochondrial pathway, whereas the cell death induced by aminochrome alone requires inhibition of autophagy-dependent degrading of damaged organelles and recycling through lysosomes. PMID:21427056

  15. Rapamycin protects livers from ischemia and reperfusion Injury via both autophagy induction and mTORC2-Akt activation

    PubMed Central

    Zhu, Jianjun; Lu, Tianfei; Yue, Shi; Shen, Xiuda; Gao, Feng; Busuttil, Ronald W.; Kupiec-Weglinski, Jerzy W.; Xia, Qiang; Zhai, Yuan

    2014-01-01

    Background Although Rapamycin (RPM) have been studied extensively in ischemia models, its functional mechanisms remains to be defined. Methods We determined how RPM impacted the pathogenesis of ischemia reperfusion injury (IRI) in a murine liver partial warm ischemia model, with emphasis on its regulation of hepatocyte death. Results RPM protected livers from IRI in the presence of fully developed liver inflammatory immune response. RPM enhanced liver autophagy induction at the reperfusion stage. Dual mTOR1/2 inhibitor Torin 1, despite its ability to induced autophagy, failed to protect livers from IRI. The treatment with RPM, but not Torin 1, resulted in the enhanced activation of the mTORC2-Akt signaling pathway activation in livers post reperfusion. Inactivation of Akt by Triciribine abolished liver protective effect of RPM. The differential cytoprotective effect of RPM and Torin 1 was confirmed in vitro in hepatocyte cultures. RPM, but not Trin 1, protected hepatocytes from stress and TNF-α induced cell death; and inhibition of either autophagy by chloroquine or Akt by Triciribine abolished RPM-mediated cytoprotection. Conclusion RPM protected livers from IRI via both autophagy and mTORC2-Akt activation mechanisms. PMID:25340604

  16. Pyrvinium targets autophagy addiction to promote cancer cell death

    PubMed Central

    Deng, Longfei; Lei, Yunlong; Liu, Rui; Li, Jingyi; Yuan, Kefei; Li, Yi; Chen, Yi; Liu, Yi; Lu, You; Edwards III, Carl K; Huang, Canhua; Wei, Yuquan

    2013-01-01

    Autophagy is a cellular catabolic process by which long-lived proteins and damaged organelles are degradated by lysosomes. Activation of autophagy is an important survival mechanism that protects cancer cells from various stresses, including anticancer agents. Recent studies indicate that pyrvinium pamoate, an FDA-approved antihelminthic drug, exhibits wide-ranging anticancer activity. Here we demonstrate that pyrvinium inhibits autophagy both in vitro and in vivo. We further demonstrate that the inhibition of autophagy is mammalian target of rapamycin independent but depends on the transcriptional inhibition of autophagy genes. Moreover, the combination of pyrvinium with autophagy stimuli improves its toxicity against cancer cells, and pretreatment of cells with 3-MA or siBeclin1 partially protects cells from pyrvinium-induced cell death under glucose starvation, suggesting that targeted autophagy addiction is involved in pyrvinium-mediated cytotoxicity. Finally, in vivo studies show that the combination therapy of pyrvinium with the anticancer and autophagy stimulus agent, 2-deoxy-𝒟-glucose (2-DG), is significantly more effective in inhibiting tumor growth than pyrvinium or 2-DG alone. This study supports a novel cancer therapeutic strategy based on targeting autophagy addiction and implicates using pyrvinium as an autophagy inhibitor in combination with chemotherapeutic agents to improve their therapeutic efficacy. PMID:23640456

  17. Quercitrin treatment protects endothelial progenitor cells from oxidative damage via inducing autophagy through extracellular signal-regulated kinase.

    PubMed

    Zhi, Kangkang; Li, Maoquan; Bai, Jun; Wu, Yongfa; Zhou, Sili; Zhang, Xiaoping; Qu, Lefeng

    2016-07-01

    Atherosclerosis is a disease resulting from impaired endothelial function, often caused by oxidant injury or inflammation. Endothelial progenitor cells (EPCs) play a critical role in repairing damaged endothelium and protecting against atherosclerosis. Quercitrin, a plant-derived flavonoid compound, displays antioxidant and anti-inflammatory activities. In this study, we showed that quercitrin treatment reduced the apoptosis of EPCs caused by oxidized low-density lipoprotein (ox-LDL) in a dose-dependent manner. Quercitrin improved tube formation, migration and adhesion of ox-LDL-treated EPCs. To determine the effect of quercitrin in vivo, EPCs treated with or without ox-LDL and quercitrin were locally injected into the ischemic hind limb muscle of nude mice. Those injected with EPCs treated with ox-LDL and quercitrin showed significantly increased local accumulation of EPCs, blood flow recovery and capillary density compared with the control and ox-LDL only groups. Furthermore, we showed that quercitrin enhanced autophagy and upregulated mitogen-activated protein kinase and ERK phosphorylation in a dose-dependent manner in vitro. Autophagy inhibitors, chloroquine and 3-methyladenine, abrogated quercitrin-enhanced autophagy caused by ox-LDL as evidenced by decreased numbers of branch points, migratory cells and adherent cells, and increased numbers of apoptotic cells. The ERK inhibitor PD98059 abrogated quercitrin-enhanced autophagy, as identified by decreased autophagosome formation and downregulated ERK phosphorylation. The inhibition of ERK did not affect the expression of Rac1, but enhanced phosphorylation of Akt. Quercitrin treatment also increased the expression of E-cadherin, and PD98059 abrogated the upregulation of E-cadherin induced by quercitrin. Our findings suggested that autophagy is a protective mechanism in EPCs exposed to oxidative damage. Quercitrin can promote autophagy through the activation of ERK and the ERK signaling pathway is therefore

  18. Heme oxygenase-1-mediated autophagy protects against pulmonary endothelial cell death and development of emphysema in cadmium-treated mice.

    PubMed

    Surolia, Ranu; Karki, Suman; Kim, Hyunki; Yu, Zhihong; Kulkarni, Tejaswini; Mirov, Sergey B; Carter, A Brent; Rowe, Steven M; Matalon, Sadis; Thannickal, Victor J; Agarwal, Anupam; Antony, Veena B

    2015-08-01

    Pulmonary exposure to cadmium, a major component of cigarette smoke, has a dramatic impact on lung function and the development of emphysema. Cigarette smoke exposure induces heme oxygenase-1 (HO-1), a cytoprotective enzyme. In this study, we employed a truncated mouse model of emphysema by intratracheal instillation of cadmium (CdCl2) solution (0.025% per 1 mg/kg body wt) in HO-1(+/+), HO-1(-/-), and overexpressing humanized HO-1 bacterial artificial chromosome (hHO-1BAC) mice. We evaluated the role of HO-1 in cadmium-induced emphysema in mice by analyzing histopathology, micro-computed tomography scans, and lung function tests. CdCl2-exposed HO-1(-/-) mice exhibited more severe emphysema compared with HO-1(+/+) or hHO-1BAC mice. Loss of pulmonary endothelial cells (PECs) from the alveolar capillary membrane is recognized to be a target in emphysema. PECs from HO-1(+/+), HO-1(-/-), and hHO-1BAC were employed to define the underlying molecular mechanism for the protection from emphysema by HO-1. Electron microscopy, expression of autophagic markers (microtubule-associated protein 1B-light chain 3 II, autophagy protein 5, and Beclin1) and apoptotic marker (cleaved caspase 3) suggested induction of autophagy and apoptosis in PECs after CdCl2 treatment. CdCl2-treated HO-1(-/-) PECs exhibited downregulation of autophagic markers and significantly increased cleaved caspase 3 expression and activity (∼4-fold higher). Moreover, hHO-1BAC PECs demonstrated upregulated autophagy and absence of cleaved caspase 3 expression or activity. Pretreatment of HO-1(+/+) PECs with rapamycin induced autophagy and resulted in reduced cell death upon cadmium treatment. Induction of autophagy following CdCl2 treatment was found to be protective from apoptotic cell death. HO-1 induced protective autophagy in PECs and mitigated cadmium-induced emphysema. PMID:26071551

  19. Characterization of an Autophagy-Related Gene MdATG8i from Apple

    PubMed Central

    Wang, Ping; Sun, Xun; Jia, Xin; Wang, Na; Gong, Xiaoqing; Ma, Fengwang

    2016-01-01

    Nutrient deficiencies restrict apple (Malus sp.) tree growth and productivity in Northwest China. The process of autophagy, a conserved degradation pathway in eukaryotic cells, has important roles in nutrient-recycling and helps improve plant performance during periods of nutrient-starvation. Little is known about the functioning of autophagy-related genes (ATGs) in apple. In this study, one of the ATG8 gene family members MdATG8i was isolated from Malus domestica. MdATG8i has conserved putative tubulin binding sites and ATG7 interaction domains. A 1865-bp promoter region cloned from apple genome DNA was predicated to have cis-regulatory elements responsive to light, environmental stresses, and hormones. MdATG8i transcriptions were induced in response to leaf senescence, nitrogen depletion, and oxidative stress. At cellular level, MdATG8i protein was expressed in the nucleus and cytoplasm of onion epidermal cells. Yeast two-hybrid tests showed that MdATG8i could interact with MdATG7a and MdATG7b. In Arabidopsis, its heterologous expression was associated with enhanced vegetative growth, leaf senescence, and tolerance to nitrogen- and carbon-starvation. MdATG8i-overexpressing “Orin” apple callus lines also displayed improved tolerance to nutrient-limited conditions. Our results demonstrate that MdATG8i protein could function in autophagy in a conserved way, as a positive regulator in the response to nutrient-starvation. PMID:27252732

  20. Characterization of an Autophagy-Related Gene MdATG8i from Apple.

    PubMed

    Wang, Ping; Sun, Xun; Jia, Xin; Wang, Na; Gong, Xiaoqing; Ma, Fengwang

    2016-01-01

    Nutrient deficiencies restrict apple (Malus sp.) tree growth and productivity in Northwest China. The process of autophagy, a conserved degradation pathway in eukaryotic cells, has important roles in nutrient-recycling and helps improve plant performance during periods of nutrient-starvation. Little is known about the functioning of autophagy-related genes (ATGs) in apple. In this study, one of the ATG8 gene family members MdATG8i was isolated from Malus domestica. MdATG8i has conserved putative tubulin binding sites and ATG7 interaction domains. A 1865-bp promoter region cloned from apple genome DNA was predicated to have cis-regulatory elements responsive to light, environmental stresses, and hormones. MdATG8i transcriptions were induced in response to leaf senescence, nitrogen depletion, and oxidative stress. At cellular level, MdATG8i protein was expressed in the nucleus and cytoplasm of onion epidermal cells. Yeast two-hybrid tests showed that MdATG8i could interact with MdATG7a and MdATG7b. In Arabidopsis, its heterologous expression was associated with enhanced vegetative growth, leaf senescence, and tolerance to nitrogen- and carbon-starvation. MdATG8i-overexpressing "Orin" apple callus lines also displayed improved tolerance to nutrient-limited conditions. Our results demonstrate that MdATG8i protein could function in autophagy in a conserved way, as a positive regulator in the response to nutrient-starvation. PMID:27252732

  1. A genetic screen for modifiers of Drosophila caspase Dcp-1 reveals caspase involvement in autophagy and novel caspase-related genes

    PubMed Central

    2010-01-01

    Background Caspases are cysteine proteases with essential functions in the apoptotic pathway; their proteolytic activity toward various substrates is associated with the morphological changes of cells. Recent reports have described non-apoptotic functions of caspases, including autophagy. In this report, we searched for novel modifiers of the phenotype of Dcp-1 gain-of-function (GF) animals by screening promoter element- inserted Drosophila melanogaster lines (EP lines). Results We screened ~15,000 EP lines and identified 72 Dcp-1-interacting genes that were classified into 10 groups based on their functions and pathways: 4 apoptosis signaling genes, 10 autophagy genes, 5 insulin/IGF and TOR signaling pathway genes, 6 MAP kinase and JNK signaling pathway genes, 4 ecdysone signaling genes, 6 ubiquitination genes, 11 various developmental signaling genes, 12 transcription factors, 3 translation factors, and 11 other unclassified genes including 5 functionally undefined genes. Among them, insulin/IGF and TOR signaling pathway, MAP kinase and JNK signaling pathway, and ecdysone signaling are known to be involved in autophagy. Together with the identification of autophagy genes, the results of our screen suggest that autophagy counteracts Dcp-1-induced apoptosis. Consistent with this idea, we show that expression of eGFP-Atg5 rescued the eye phenotype caused by Dcp-1 GF. Paradoxically, we found that over-expression of full-length Dcp-1 induced autophagy, as Atg8b-GFP, an indicator of autophagy, was increased in the eye imaginal discs and in the S2 cell line. Taken together, these data suggest that autophagy suppresses Dcp-1-mediated apoptotic cell death, whereas Dcp-1 positively regulates autophagy, possibly through feedback regulation. Conclusions We identified a number of Dcp-1 modifiers that genetically interact with Dcp-1-induced cell death. Our results showing that Dcp-1 and autophagy-related genes influence each other will aid future investigations of the

  2. Conophylline protects cells in cellular models of neurodegenerative diseases by inducing mammalian target of rapamycin (mTOR)-independent autophagy.

    PubMed

    Sasazawa, Yukiko; Sato, Natsumi; Umezawa, Kazuo; Simizu, Siro

    2015-03-01

    Macroautophagy is a cellular response that leads to the bulk, nonspecific degradation of cytosolic components, including organelles. In recent years, it has been recognized that autophagy is essential for prevention of neurodegenerative diseases, including Parkinson disease (PD) and Huntington disease (HD). Here, we show that conophylline (CNP), a vinca alkaloid, induces autophagy in an mammalian target of rapamycin-independent manner. Using a cellular model of PD, CNP suppressed protein aggregation and protected cells from cell death caused by treatment with 1-methyl-4-phenylpyridinium, a neurotoxin, by inducing autophagy. Moreover, in the HD model, CNP also eliminated mutant huntingtin aggregates. Our findings demonstrate the possible use of CNP as a therapeutic drug for neurodegenerative disorders, including PD and HD. PMID:25596530

  3. Conophylline Protects Cells in Cellular Models of Neurodegenerative Diseases by Inducing Mammalian Target of Rapamycin (mTOR)-independent Autophagy*

    PubMed Central

    Sasazawa, Yukiko; Sato, Natsumi; Umezawa, Kazuo; Simizu, Siro

    2015-01-01

    Macroautophagy is a cellular response that leads to the bulk, nonspecific degradation of cytosolic components, including organelles. In recent years, it has been recognized that autophagy is essential for prevention of neurodegenerative diseases, including Parkinson disease (PD) and Huntington disease (HD). Here, we show that conophylline (CNP), a vinca alkaloid, induces autophagy in an mammalian target of rapamycin-independent manner. Using a cellular model of PD, CNP suppressed protein aggregation and protected cells from cell death caused by treatment with 1-methyl-4-phenylpyridinium, a neurotoxin, by inducing autophagy. Moreover, in the HD model, CNP also eliminated mutant huntingtin aggregates. Our findings demonstrate the possible use of CNP as a therapeutic drug for neurodegenerative disorders, including PD and HD. PMID:25596530

  4. Taurine protects against As2O3-induced autophagy in livers of rat offsprings through PPARγ pathway

    PubMed Central

    Bai, Jie; Yao, Xiaofeng; Jiang, Liping; Zhang, Qiaoting; Guan, Huai; Liu, Shuang; Wu, Wei; Qiu, Tianming; Gao, Ni; Yang, Lei; Yang, Guang; Sun, Xiance

    2016-01-01

    Chronic exposures to arsenic had been associated with metabolism diseases. Peroxisome proliferator-activated receptor gamma (PPARγ) was found in the liver, regulated metabolism. Here, we found that the expression of PPARγ was decreased, the generation of reactive oxygen species (ROS) and autophagy were increased after treatment with As2O3 in offsprings’ livers. Taurine (Tau), a sulfur-containing β–amino acid could reverse As2O3-inhibited PPARγ. Tau also inhibit the generation of ROS and autophagy. We also found that As2O3 caused autophagic cell death and ROS accelerated in HepG2 cells. Before incubation with As2O3, the cells were pretreated with PPARγ activator Rosiglitazone (RGS), we found that autophagy and ROS was inhibited in HepG2 cells, suggesting that inhibition of PPARγ contributed to As2O3-induced autophagy and the generation of ROS. After pretreatment with Tau, the level of PPARγ was improved and the autophagy and ROS was inhibited in As2O3-treated cells, suggesting that Tau could protect hepatocytes against As2O3 through modulating PPARγ pathway. PMID:27291853

  5. Taurine protects against As2O3-induced autophagy in livers of rat offsprings through PPARγ pathway.

    PubMed

    Bai, Jie; Yao, Xiaofeng; Jiang, Liping; Zhang, Qiaoting; Guan, Huai; Liu, Shuang; Wu, Wei; Qiu, Tianming; Gao, Ni; Yang, Lei; Yang, Guang; Sun, Xiance

    2016-01-01

    Chronic exposures to arsenic had been associated with metabolism diseases. Peroxisome proliferator-activated receptor gamma (PPARγ) was found in the liver, regulated metabolism. Here, we found that the expression of PPARγ was decreased, the generation of reactive oxygen species (ROS) and autophagy were increased after treatment with As2O3 in offsprings' livers. Taurine (Tau), a sulfur-containing β-amino acid could reverse As2O3-inhibited PPARγ. Tau also inhibit the generation of ROS and autophagy. We also found that As2O3 caused autophagic cell death and ROS accelerated in HepG2 cells. Before incubation with As2O3, the cells were pretreated with PPARγ activator Rosiglitazone (RGS), we found that autophagy and ROS was inhibited in HepG2 cells, suggesting that inhibition of PPARγ contributed to As2O3-induced autophagy and the generation of ROS. After pretreatment with Tau, the level of PPARγ was improved and the autophagy and ROS was inhibited in As2O3-treated cells, suggesting that Tau could protect hepatocytes against As2O3 through modulating PPARγ pathway. PMID:27291853

  6. Metformin Protects Against Cisplatin-Induced Tubular Cell Apoptosis and Acute Kidney Injury via AMPKα-regulated Autophagy Induction

    PubMed Central

    Li, Jianzhong; Gui, Yuan; Ren, Jiafa; Liu, Xin; Feng, Ye; Zeng, Zhifeng; He, Weichun; Yang, Junwei; Dai, Chunsun

    2016-01-01

    Metformin, one of the most common prescriptions for patients with type 2 diabetes, is reported to protect the kidney from gentamicin-induced nephrotoxicity. However, the role and mechanisms for metformin in preventing cisplatin-induced nephrotoxicity remains largely unknown. In this study, a single intraperitoneal injection of cisplatin was employed to induce acute kidney injury (AKI) in CD1 mice. The mice exhibited severe kidney dysfunction and histological damage at day 2 after cisplatin injection. Pretreatment of metformin could markedly attenuate cisplatin-induced acute kidney injury, tubular cell apoptosis and inflammatory cell accumulation in the kidneys. Additionally, pretreatment of metformin could enhance both AMPKα phosphorylation and autophagy induction in the kidneys after cisplatin injection. In cultured NRK-52E cells, a rat kidney tubular cell line, metformin could stimulate AMPKα phosphorylation, induce autophagy and inhibit cisplatin-induced cell apoptosis. Blockade of either AMPKα activation or autophagy induction could largely abolish the protective effect of metformin in cisplatin-induced cell death. Together, this study demonstrated that metformin may protect against cisplatin-induced tubular cell apoptosis and AKI through stimulating AMPKα activation and autophagy induction in the tubular cells. PMID:27052588

  7. Minocycline induces protective autophagy in vascular endothelial cells exposed to an in vitro model of ischemia/reperfusion-induced injury

    PubMed Central

    DONG, WENBIN; XIAO, SHIGENG; CHENG, MIN; YE, XIAODI; ZHENG, GAOLI

    2016-01-01

    Minocycline has been reported to exhibit advantageous effects on ischemic stroke; however, the precise mechanism of minocycline remains to be established. In the present study, human umbilical vein endothelial cells (HUVECs) were subjected to in vitro simulated ischemia/reperfusion conditions to determine the potential effect of minocycline-induced autophagy on HUVEC damage under oxygen-glucose deprivation/reperfusion (OGD/R). The study demonstrated that minocycline enhanced autophagy in a dose-dependent manner in HUVECs exposed to OGD/R, and only low-dose minocycline protected HUVECs from OGD/R-induced damage. Subsequently, 3-methyladenine (3-MA) was added into the culture media and the protective effect of minocycline was abolished. At the same time, it has been observed that simultaneous treatment with 3-MA also inhibited the autophagy activity induced by minocycline. This finding could suggest that autophagy induced by minocycline serves as one of the potential protective mechanism underlying the beneficial effects of minocycline on ischemic injury. PMID:26893833

  8. Autophagy Protects Monocytes from Wolbachia Heat Shock Protein 60–Induced Apoptosis and Senescence

    PubMed Central

    Kamalakannan, Vijayan; Shiny, Abijit; Babu, Subash; Narayanan, Rangarajan Badri

    2015-01-01

    Monocyte dysfunction by filarial antigens has been a major mechanism underlying immune evasion following hyporesponsiveness during patent lymphatic filariasis. Recent studies have initiated a paradigm shift to comprehend the immunological interactions of Wolbachia and its antigens in inflammation, apoptosis, lymphocyte anergy, etc. Here we showed that recombinant Wolbachia heat shock protein 60 (rWmhsp60) interacts with TLR-4 and induces apoptosis in monocytes of endemic normal but not in chronic patients. Higher levels of reactive oxygen species (ROS) induced after TLR-4 stimulation resulted in loss of mitochondrial membrane potential and caspase cascade activation, which are the plausible reason for apoptosis. Furthermore, release in ROS owing to TLR-4 signaling resulted in the activation of NF-κB p65 nuclear translocation which leads to inflammation and apoptosis via TNF receptor pathway following the increase in IL-6 and TNF-α level. Here for the first time, we report that in addition to apoptosis, rWmhsp60 antigen in filarial pathogenesis also induces molecular senescence in monocytes. Targeting TLR-4, therefore, presents a promising candidate for treating rWmhsp60-induced apoptosis and senescence. Strikingly, induction of autophagy by rapamycin detains TLR-4 in late endosomes and subverts TLR-4-rWmhsp60 interaction, thus protecting TLR-4–mediated apoptosis and senescence. Furthermore, rapamycin-induced monocytes were unresponsive to rWmhsp60, and activated lymphocytes following PHA stimulation. This study demonstrates that autophagy mediates the degradation of TLR-4 signaling and protects monocytes from rWmhsp60 induced apoptosis and senescence. PMID:25849993

  9. Autophagy protects monocytes from Wolbachia heat shock protein 60-induced apoptosis and senescence.

    PubMed

    Kamalakannan, Vijayan; Shiny, Abijit; Babu, Subash; Narayanan, Rangarajan Badri

    2015-04-01

    Monocyte dysfunction by filarial antigens has been a major mechanism underlying immune evasion following hyporesponsiveness during patent lymphatic filariasis. Recent studies have initiated a paradigm shift to comprehend the immunological interactions of Wolbachia and its antigens in inflammation, apoptosis, lymphocyte anergy, etc. Here we showed that recombinant Wolbachia heat shock protein 60 (rWmhsp60) interacts with TLR-4 and induces apoptosis in monocytes of endemic normal but not in chronic patients. Higher levels of reactive oxygen species (ROS) induced after TLR-4 stimulation resulted in loss of mitochondrial membrane potential and caspase cascade activation, which are the plausible reason for apoptosis. Furthermore, release in ROS owing to TLR-4 signaling resulted in the activation of NF-κB p65 nuclear translocation which leads to inflammation and apoptosis via TNF receptor pathway following the increase in IL-6 and TNF-α level. Here for the first time, we report that in addition to apoptosis, rWmhsp60 antigen in filarial pathogenesis also induces molecular senescence in monocytes. Targeting TLR-4, therefore, presents a promising candidate for treating rWmhsp60-induced apoptosis and senescence. Strikingly, induction of autophagy by rapamycin detains TLR-4 in late endosomes and subverts TLR-4-rWmhsp60 interaction, thus protecting TLR-4-mediated apoptosis and senescence. Furthermore, rapamycin-induced monocytes were unresponsive to rWmhsp60, and activated lymphocytes following PHA stimulation. This study demonstrates that autophagy mediates the degradation of TLR-4 signaling and protects monocytes from rWmhsp60 induced apoptosis and senescence. PMID:25849993

  10. Autophagy Induction Protects Against 7-Oxysterol-induced Cell Death via Lysosomal Pathway and Oxidative Stress

    PubMed Central

    Yuan, Xi-Ming; Sultana, Nargis; Siraj, Nabeel; Ward, Liam J.; Ghafouri, Bijar; Li, Wei

    2016-01-01

    7-Oxysterols are major toxic components in oxidized low-density lipoprotein and human atheroma lesions, which cause lysosomal membrane permeabilization (LMP) and cell death. Autophagy may function as a survival mechanism in this process. Here, we investigated whether 7-oxysterols mixed in an atheroma-relevant proportion induce autophagy, whether autophagy induction influences 7-oxysterol-mediated cell death, and the underlying mechanisms, by focusing on cellular lipid levels, oxidative stress, and LMP in 7-oxysterol-treated macrophages. We found that 7-oxysterols induced cellular lipid accumulation, autophagy dysfunction, and cell death in the form of both apoptosis and necrosis. Exposure to 7-oxysterols induced autophagic vacuole synthesis in the form of increased autophagy marker microtubule-associated protein 1A/1B-light chain 3 (LC3) and LC3-phosphatidylethanolamine conjugate (LC3-II) and autophagic vacuole formation. This led to an accumulation of p62, indicating a reduction in autophagic vacuole degradation. Importantly, autophagy induction significantly reduced 7-oxysterol-mediated cell death by diminishing LMP and oxidative stress. Moreover, autophagy induction minimized cellular lipid accumulation induced by 7-oxysterols. These findings highlight the importance of autophagy in combating cellular stress, LMP, and cell death in atherosclerosis. Therefore, activation of the autophagy pathway may be a potential therapeutic strategy for prevention of necrotic core formation in atherosclerotic lesions. PMID:26966389

  11. Autophagy protects against dasatinib-induced hepatotoxicity via p38 signaling

    PubMed Central

    Yang, Xiaochun; Wang, Jincheng; Dai, Jiabin; Shao, Jinjin; Ma, Jian; Chen, Chao; Ma, Shenglin; He, Qiaojun; Luo, Peihua; Yang, Bo

    2015-01-01

    Liver dysfunction is a common side effect associated with the treatment of dasatinib and its mechanism is poorly understood. Autophagy has been thought to be a potent survival or death factor for liver dysfunction, which may shed the light on a novel strategy for the intervention of hepatotoxicity caused by dasatinib. In this study, we show for the first time that autophagy is induced, which is consistent with the formation of liver damage. Autophagy inhibition exacerbated dasatinib-induced liver failure, suggesting that autophagy acted as a self-defense mechanism to promote survival. Oxidative stress has been shown to be an important stimulus for autophagy and hepatotoxicity. Interestingly, dasatinib increased the activity of p38, which is a critical modulator of the oxidative stress related to liver injury and autophagy. p38 silencing significantly blocked LC3-II induction and p62 reduction by dasatinib, which was accompanied by increased caspase-3 and PARP cleavage, indicating that autophagy alleviated dasatinib-induced hepatotoxicity via p38 signaling. Finally, the p38 agonist isoproterenol hydrochloride (ISO) alleviated dasatinib-induced liver failure by enhancing autophagy without affecting the anticancer activity of dasatinib. Thus, this study revealed that p38-activated autophagy promoted survival during liver injury, which may provide novel approaches for managing the clinical applications of dasatinib. PMID:25749037

  12. Inhibition of autophagy in EBV-positive Burkitt's lymphoma cells enhances EBV lytic genes expression and replication.

    PubMed

    De Leo, A; Colavita, F; Ciccosanti, F; Fimia, G M; Lieberman, P M; Mattia, E

    2015-01-01

    Autophagy, an important degradation system involved in maintaining cellular homeostasis, serves also to eliminate pathogens and process their fragments for presentation to the immune system. Several viruses have been shown to interact with the host autophagic machinery to suppress or make use of this cellular catabolic pathway to enhance their survival and replication. Epstein Barr virus (EBV) is a γ-herpes virus associated with a number of malignancies of epithelial and lymphoid origin in which establishes a predominantly latent infection. Latent EBV can periodically reactivate to produce infectious particles that allow the virus to spread and can lead to the death of the infected cell. In this study, we analyzed the relationship between autophagy and EBV reactivation in Burkitt's lymphoma cells. By monitoring autophagy markers and EBV lytic genes expression, we demonstrate that autophagy is enhanced in the early phases of EBV lytic activation but decreases thereafter concomitantly with increased levels of EBV lytic proteins. In a cell line defective for late antigens expression, we found an inverse correlation between EBV early antigens expression and autophagosomes formation, suggesting that early after activation, the virus is able to suppress autophagy. We report here for the first time that inhibition of autophagy by Bafilomycin A1 or shRNA knockdown of Beclin1 gene, highly incremented EBV lytic genes expression as well as intracellular viral DNA and viral progeny yield. Taken together, these findings indicate that EBV activation induces the autophagic response, which is soon inhibited by the expression of EBV early lytic products. Moreover, our findings open the possibility that pharmacological inhibitors of autophagy may be used to enhance oncolytic viral therapy of EBV-related lymphomas. PMID:26335716

  13. Inhibition of autophagy in EBV-positive Burkitt's lymphoma cells enhances EBV lytic genes expression and replication

    PubMed Central

    De Leo, A; Colavita, F; Ciccosanti, F; Fimia, G M; Lieberman, P M; Mattia, E

    2015-01-01

    Autophagy, an important degradation system involved in maintaining cellular homeostasis, serves also to eliminate pathogens and process their fragments for presentation to the immune system. Several viruses have been shown to interact with the host autophagic machinery to suppress or make use of this cellular catabolic pathway to enhance their survival and replication. Epstein Barr virus (EBV) is a γ-herpes virus associated with a number of malignancies of epithelial and lymphoid origin in which establishes a predominantly latent infection. Latent EBV can periodically reactivate to produce infectious particles that allow the virus to spread and can lead to the death of the infected cell. In this study, we analyzed the relationship between autophagy and EBV reactivation in Burkitt's lymphoma cells. By monitoring autophagy markers and EBV lytic genes expression, we demonstrate that autophagy is enhanced in the early phases of EBV lytic activation but decreases thereafter concomitantly with increased levels of EBV lytic proteins. In a cell line defective for late antigens expression, we found an inverse correlation between EBV early antigens expression and autophagosomes formation, suggesting that early after activation, the virus is able to suppress autophagy. We report here for the first time that inhibition of autophagy by Bafilomycin A1 or shRNA knockdown of Beclin1 gene, highly incremented EBV lytic genes expression as well as intracellular viral DNA and viral progeny yield. Taken together, these findings indicate that EBV activation induces the autophagic response, which is soon inhibited by the expression of EBV early lytic products. Moreover, our findings open the possibility that pharmacological inhibitors of autophagy may be used to enhance oncolytic viral therapy of EBV-related lymphomas. PMID:26335716

  14. The autophagy gene Atg16l1 differentially regulates Treg and TH2 cells to control intestinal inflammation

    PubMed Central

    Kabat, Agnieszka M; Moghaddam, Amin E; Pearson, Claire F; Laing, Adam; Abeler-Dörner, Lucie; Forman, Simon P; Grencis, Richard K; Sattentau, Quentin; Simon, Anna Katharina; Pott, Johanna; Maloy, Kevin J

    2016-01-01

    A polymorphism in the autophagy gene Atg16l1 is associated with susceptibility to inflammatory bowel disease (IBD); however, it remains unclear how autophagy contributes to intestinal immune homeostasis. Here, we demonstrate that autophagy is essential for maintenance of balanced CD4+ T cell responses in the intestine. Selective deletion of Atg16l1 in T cells in mice resulted in spontaneous intestinal inflammation that was characterized by aberrant type 2 responses to dietary and microbiota antigens, and by a loss of Foxp3+ Treg cells. Specific ablation of Atg16l1 in Foxp3+ Treg cells in mice demonstrated that autophagy directly promotes their survival and metabolic adaptation in the intestine. Moreover, we also identify an unexpected role for autophagy in directly limiting mucosal TH2 cell expansion. These findings provide new insights into the reciprocal control of distinct intestinal TH cell responses by autophagy, with important implications for understanding and treatment of chronic inflammatory disorders. DOI: http://dx.doi.org/10.7554/eLife.12444.001 PMID:26910010

  15. Distinct roles for the p53-like transcription factor XprG and autophagy genes in the response to starvation.

    PubMed

    Katz, Margaret E; Buckland, Rebecca; Hunter, Cameron C; Todd, Richard B

    2015-10-01

    Autophagy and autolysis are two cannibalistic pathways which allow filamentous fungi to obtain nutrients once environmental nutrient sources are exhausted. In Aspergillus nidulans, the effects of mutations in two key autophagy genes, atgA, the ATG1 ortholog, and atgH, the ATG8 ortholog, were compared with mutations in xprG, which encodes a transcriptional activator that plays a key role in autolysis. The anti-fungal drug rapamycin induces autophagy in a range of organisms. Mutations in atgA and atgH did not alter sensitivity to rapamycin, which inhibits growth and asexual spore production (conidiation), indicating that autophagy is not required for rapamycin sensitivity in A. nidulans. In contrast, inhibition of conidiation by rapamcyin was partially suppressed by the xprG1 gain-of-function mutation, indicating that XprG acts in the pathway(s) affected by rapamycin. It was anticipated that the absence of an intact autophagy pathway would accelerate the response to starvation. However, extracellular and intracellular protease production in response to carbon or nitrogen starvation was not increased in the atgAΔ and atgHΔ mutants, and the onset of autolysis was not accelerated. Compared to wild-type strains and the xprGΔ and xprG1 mutants, conidiation of the autophagy mutants was reduced in carbon- or nitrogen-limiting conditions but not during growth on nutrient-sufficient medium. Nuclear localization of the global nitrogen regulator AreA in response to nitrogen starvation was blocked in the xprG2 loss-of-function mutant, but not in the atgHΔ mutant. Conversely, the atgAΔ mutation but not the xprGΔ mutation prevented vacuolar accumulation of GFP-AtgH, a hallmark of autophagy. These results indicate that in A. nidulans there is little interaction between autophagy and autolysis and the two pathways are activated in parallel during starvation. PMID:26296599

  16. Expression analysis of autophagy-related genes in the hard tick Haemaphysalis longicornis.

    PubMed

    Umemiya-Shirafuji, Rika; Galay, Remil Linggatong; Maeda, Hiroki; Kawano, Suguru; Tanaka, Tetsuya; Fukumoto, Shinya; Suzuki, Hiroshi; Tsuji, Naotoshi; Fujisaki, Kozo

    2014-03-17

    Ticks are obligate hematophagous arthropods with unique life cycles characterized by relatively short feeding periods and long non-feeding periods. They ambush a suitable host animal while staying in a pasture without any food source for up to several months. To understand the molecular mechanisms underlying their exceptional viability, we focused on autophagy, a proteolysis system via the lysosomes that is induced by starvation in eukaryotes. We hypothesized that starved conditions facilitate autophagy during host-seeking periods in the life cycle of the tick. To date, homologues of five autophagy-related (ATG) genes, ATG3, ATG4, ATG6, ATG8, and ATG12, have been identified from the hard tick Haemaphysalis longicornis. We showed previously that the mRNA levels of H. longicornis ATG (HlATG) genes were higher during the non-feeding period than the feeding period in the nymphal to adult stages. In addition, the expressions of HlATG3, HlATG4, HlATG8 and HlATG12 were highest in the egg compared to the other developmental stages in the same tick. In the present study, we used real-time polymerase chain reaction to examine the expression profiles of HlATG genes in the embryonic stage, larval to nymphal stages, and in internal organs of female ticks. We found that the HlATG genes were expressed at the highest levels in developing eggs on day 0 after oviposition. The levels of HlATG4 and HlATG8 were higher during the non-feeding period than the feeding period in the larval to nymphal stages. In the adults, the unfed condition appeared to be associated with the increased expression of HlATG genes in the fat body and midgut, which are nutrient storage organs; however, the expression patterns of HlATG genes varied in other organs. These results suggest that an up-regulation of HlATG genes is not always induced in different organs of unfed female ticks. Taken together, our findings raise the new possibility that HlATG genes play distinct biological roles in eggs, unfed ticks

  17. Acid-induced autophagy protects human lung cancer cells from apoptosis by activating ER stress.

    PubMed

    Xie, Wen-Yue; Zhou, Xiang-Dong; Li, Qi; Chen, Ling-Xiu; Ran, Dan-Hua

    2015-12-10

    An acidic tumor microenvironment exists widely in solid tumors. However, the detailed mechanism of cell survival under acidic stress remains unclear. The aim of this study is to clarify whether acid-induced autophagy exists and to determine the function and mechanism of autophagy in lung cancer cells. We have found that acute low pH stimulated autophagy by increasing LC3-positive punctate vesicles, increasing LC3 II expression levels and reducing p62 protein levels. Additionally, autophagy was inhibited by the addition of Baf or knockdown of Beclin 1, and cell apoptosis was increased markedly. In mouse tumors, the expression of cleaved caspase3 and p62 was enhanced by oral treatment with sodium bicarbonate, which can raise the intratumoral pH. Furthermore, the protein levels of ER stress markers, including p-PERK, p-eIF2α, CHOP, XBP-1s and GRP78, were also increased in response to acidic pH. The antioxidant NAC, which reduces ROS accumulation, alleviated acid-mediated ER stress and autophagy, and knocking down GRP78 reduced autophagy activation under acidic conditions, which suggests that autophagy was induced by acidic pH through ER stress. Taken together, these results indicate that the acidic microenvironment in non-small cell lung cancer cells promotes autophagy by increasing ROS-ER stress, which serves as a survival adaption in this setting. PMID:26559141

  18. Autophagy Gene Activity May Act As a Key Factor for Sensitivity of Tumor Cells to Oncolytic Vesicular Stomatitis Virus

    PubMed Central

    Nabizadeh, Arezoo; Bamdad, Taravat; Arefian, Ehsan; Razavi Nikoo, Seyed Hadi

    2016-01-01

    Background: Beclin1 is an important, primary molecule for autophagy. Objectives: It is suggested that the control of the autophagy path increases the sensitivity of tumor cells to VSV. Materials and Methods: In this study, the degree of Beclin1 gene expression in two cell lines, HeLa and A549, has been examined and the percentage of living cells subsequent infection with virus has been evaluated by MTT assay method. Results: The results showed that the degree of Beclin1 gene expression in HeLa cells in comparison with A549 cells has reduced, and the sensitivity of these cells to vesicular stomatits virus (VSV) oncolysis is more than A549. Conclusions: It seems that by using some methods for reducing autophagy, it is possible to make tumor cells more sensitive to virotherapy and even other treatments. PMID:27366311

  19. Altered Autophagy-Associated Genes Expression in T Cells of Oral Lichen Planus Correlated with Clinical Features

    PubMed Central

    Tan, Ya-Qin; Zhang, Jing; Du, Ge-Fei; Lu, Rui; Chen, Guan-Ying; Zhou, Gang

    2016-01-01

    Oral lichen planus (OLP) is a T cell-mediated inflammatory autoimmune disease. Autophagy has emerged as a fundamental trafficking event in mediating T cell response, which plays crucial roles in innate and adaptive immunity. The present study mainly investigated the mRNA expression of autophagy-associated genes in peripheral blood T cells of OLP patients and evaluated correlations between their expression and the clinical features of OLP. Five differentially expressed autophagy-associated genes were identified by autophagy array. Quantitative real-time RT-PCR results confirmed that IGF1 expression in the peripheral blood T cells of OLP patients was significantly higher than that in controls, especially in female and middle-aged (30–50 years old) OLP patients. In addition, ATG9B mRNA levels were significantly lower in nonerosive OLP patients. However, no significant differences were found in the expression of HGS, ESR1, and SNCA between OLP patients and controls. Taken together, dysregulation of T cell autophagy may be involved in immune response of OLP and may be correlated with clinical patterns. PMID:26980945

  20. Peroxisome proliferator-activated receptor α activation attenuates the inflammatory response to protect the liver from acute failure by promoting the autophagy pathway.

    PubMed

    Jiao, M; Ren, F; Zhou, L; Zhang, X; Zhang, L; Wen, T; Wei, L; Wang, X; Shi, H; Bai, L; Zhang, X; Zheng, S; Zhang, J; Chen, Y; Han, Y; Zhao, C; Duan, Z

    2014-01-01

    Peroxisome proliferator-activated receptor α (PPARα) has been reported to induce a potent anti-inflammatory response. Autophagy is a recently recognized rudimentary cellular response to inflammation and injury. The aim of the present study was to test the hypothesis that PPARα activation mediates autophagy to inhibit liver inflammation and protect against acute liver failure (ALF). PPARα expression during ALF and the impact of PPARα activation by Wy-14 643 on the hepatic immune response were studied in a D-galactosamine/lipopolysaccharide-induced mouse model. Autophagy was inhibited by 3-methyladenine or small interfering RNA (siRNA) against Atg7. In both the mouse model and human ALF subjects, PPARα was significantly downregulated in the injured liver. PPARα activation by pretreatment with Wy-14 643 protected against liver injury in mice. The protective effect of PPARα activation relied on the suppression of inflammatory mechanisms through the induction of autophagy. This hypothesis is supported by the following evidence: first, PPARα activation suppressed proinflammatory responses and inhibited phosphorylated NF-κBp65, phosphorylated JNK and phosphorylated ERK pathways in vivo. Second, protection by PPARα activation was due to the induction of autophagy because inhibition of autophagy by 3-methyladenine or Atg7 siRNA reversed liver protection and inflammation. Third, PPARα activation directly induced autophagy in primary macrophages in vitro, which protected cells from a lipopolysaccharide-induced proinflammatory response. Here, for the first time, we have demonstrated that PPARα-mediated induction of autophagy ameliorated liver injury in cases of ALF by attenuating inflammatory responses, indicating a potential therapeutic application for ALF treatment. PMID:25165883

  1. Amino acids downregulate the expression of several autophagy-related genes in rainbow trout myoblasts.

    PubMed

    Seiliez, Iban; Gabillard, Jean-Charles; Riflade, Marine; Sadoul, Bastien; Dias, Karine; Avérous, Julien; Tesseraud, Sophie; Skiba, Sandrine; Panserat, Stéphane

    2012-03-01

    Many fish species experience long periods of fasting often associated with seasonal reductions in water temperature and prey availability or spawning migrations. During periods of nutrient restriction, changes in metabolism occur to provide cellular energy via catabolic processes. Muscle is particularly affected by prolonged fasting as proteins of this tissue act as a major energy source. However, the molecular components involved in muscle protein degradation as well as the regulatory networks that control their function are still incompletely defined in fish. The present work aimed to characterize the response of the autophagy-lysosomal degradative pathway to nutrient and serum availability in primary culture of rainbow trout myoblasts. In this aim, 4-day-old cells were incubated in a serum and amino acid-rich medium (complete medium), a serum and amino acid-deprived medium (minimal medium) or a minimal medium plus amino acids, and both the transcription-independent short-term response and the transcription-dependent long-term response of the autophagy-lysosomal degradative pathway were analyzed. We report that serum and amino acids withdrawal is accompanied by a rapid increase of autophagosome formation but also by a slower induction of the expression of several autophagy-related genes (LC3B, gabarapl1, atg4b). We also showed that this latter response is controlled by amino acid (AA) availability and that both TOR-dependent and TOR-independent pathways are involved in this effect. Together these results suggest an important role for AA released by muscle proteolysis during the fasting period in regulating the subtle balance between using proteins as disposable furniture to provide energy, and conserving muscle through protein sparing. PMID:22252009

  2. Association of autophagy related gene polymorphisms with neutrophilic airway inflammation in adult asthma

    PubMed Central

    Pham, Duy Le; Kim, Seung-Hyun; Losol, Purevsuren; Yang, Eun-Mi; Shin, Yoo Seob; Ye, Young-Min; Park, Hae-Sim

    2016-01-01

    Background/Aims: Role of autophagy in neutrophil function and the association of autophagy and autophagy related (ATG) gene polymorphisms with asthma susceptibility were suggested. In this study, we investigated the genetic association of ATG5 and ATG7 polymorphisms with asthma risk, severity and neutrophilic airway inflammation. Methods: We recruited 408 asthma patients and 201 healthy controls. Sputum neutrophil counts were determined by H&E staining. Serum interleukin 8 (IL-8) levels were measured by enzyme-linked immunosorbent assay (ELISA). Genetic polymorphisms of ATG5 (–769T>C, –335G>A, and 8830C>T) and ATG7 (–100A>G and 25108G>C) were genotyped. The functional activities of ATG5 –769T>C and –335G>A variants were investigated by luciferase reporter assays. Results: No associations of ATG5 and ATG7 polymorphisms with asthma susceptibility and severity were found. ATG5 –769T>C and –335G>A were in complete linkage disequilibrium. In the asthma group, GA/AA genotypes at ATG5 –335G>A were associated with higher neutrophil counts in sputum (p < 0.05); CC/TT genotype at ATG5 8830C>T associated with lower FEV1% predicted value (p < 0.05). DNA fragments containing ATG5 –769T and –335G alleles had higher promoter activities compared to those with –769C and –335A in both human airway epithelial cells (A549, p < 0.01) and human mast cell (HMC-1, p < 0.001). GG and CC genotype at ATG7 –100A>G and 25108G>C were significantly associated with high serum levels of IL-8 (p < 0.05 for both variants). Conclusions: Genetic polymorphisms of ATG5 and ATG7 could contribute to neutrophilic airway inflammation in the pathogenesis of adult asthma. PMID:26701229

  3. (Poly)phenols protect from α-synuclein toxicity by reducing oxidative stress and promoting autophagy.

    PubMed

    Macedo, Diana; Tavares, Lucélia; McDougall, Gordon J; Vicente Miranda, Hugo; Stewart, Derek; Ferreira, Ricardo B; Tenreiro, Sandra; Outeiro, Tiago F; Santos, Cláudia N

    2015-03-15

    Parkinson's disease (PD) is the most common movement neurodegenerative disorder and is associated with the aggregation of α-synuclein (αSyn) and oxidative stress, hallmarks of the disease. Although the precise molecular events underlying αSyn aggregation are still unclear, oxidative stress is known to contribute to this process. Therefore, agents that either prevent oxidative stress or inhibit αSyn toxicity are expected to constitute potential drug leads for PD. Both pre-clinical and clinical studies provided evidence that (poly)phenols, pure or in extracts, might protect against neurodegenerative disorders associated with oxidative stress in the brain. In this study, we analyzed, for the first time, a (poly)phenol-enriched fraction (PEF) from leaves of Corema album, and used in vitro and cellular models to evaluate its effects on αSyn toxicity and aggregation. Interestingly, the PEF promoted the formation of non-toxic αSyn species in vitro, and inhibited its toxicity and aggregation in cells, by promoting the autophagic flux and reducing oxidative stress. Thus, C. album (poly)phenols appear as promising cytoprotective compounds, modulating central events in the pathogenesis of PD, such as αSyn aggregation and the impairment of autophagy. Ultimately, the understanding of the molecular effects of (poly)phenols will open novel opportunities for the exploitation of their beneficial effects and for drug development. PMID:25432533

  4. ZLN005 protects cardiomyocytes against high glucose-induced cytotoxicity by promoting SIRT1 expression and autophagy.

    PubMed

    Li, Wenju; Li, Xiaoli; Wang, Bin; Chen, Yan; Xiao, Aiping; Zeng, Di; Ou, Dongbo; Yan, Song; Li, Wei; Zheng, Qiangsun

    2016-07-01

    Diabetic cardiomyopathy increases the risk for the development of heart failure independent of coronary artery disease and hypertension. Either type 1 or type 2 diabetes is often accompanied by varying degrees of hyperglycemia, which has been proven to induce myocardial apoptosis in animal models. Recently, a novel small molecule, ZLN005, has been reported to show antidiabetic efficacy in a mouse model, possibly by induction of PGC-1α expression. In this study, we investigated whether ZLN005 protects cardiomyocytes against high glucose-induced cytotoxicity and the mechanisms involved. Neonatal mouse cardiomyocytes were incubated with media containing 5.5 or 33mM glucose for 24h in the presence or absence of ZLN005. ZLN005 treatment led to ameliorated cardiomyocyte oxidative injury, enhanced cell viability, and reduced apoptosis in the high glucose environment. Western blot analysis revealed that high glucose suppressed cardiomyocyte autophagy, whereas ZLN005 increased the expression of autophagy marker proteins ATG5, beclin1, and LC3 II/LC3 I; this increase was accompanied by increased expression of SIRT1. Furthermore, EX527, a SIRT1-specific inhibitor, weakened the protective effects of ZLN005 on cardiomyocytes subjected to high glucose. Taken together, these results suggest that ZLN005 suppresses high glucose-induced cardiomyocyte injury by promoting SIRT1 expression and autophagy. PMID:27208585

  5. Autophagy plays an important role in protecting Pacific oysters from OsHV-1 and Vibrio aestuarianus infections

    PubMed Central

    Moreau, Pierrick; Moreau, Kevin; Segarra, Amélie; Tourbiez, Delphine; Travers, Marie-Agnès; Rubinsztein, David C; Renault, Tristan

    2015-01-01

    Recent mass mortality outbreaks around the world in Pacific oysters, Crassostrea gigas, have seriously affected the aquaculture economy. Although the causes for these mortality outbreaks appear complex, infectious agents are involved. Two pathogens are associated with mass mortality outbreaks, the virus ostreid herpesvirus 1 (OsHV-1) and the bacterium Vibrio aestuarianus. Here we describe the interactions between these 2 pathogens and autophagy, a conserved intracellular pathway playing a key role in innate immunity. We show for the first time that autophagy pathway is present and functional in Pacific oysters and plays an important role to protect animals from infections. This study contributes to better understand the innate immune system of Pacific oysters. PMID:25714877

  6. ROS-Mediated Autophagy Induced by Dysregulation of Lipid Metabolism Plays a Protective Role in Colorectal Cancer Cells Treated with Gambogic Acid

    PubMed Central

    Zhang, Haiyuan; Lei, Yunlong; Yuan, Ping; Li, Lingjun; Luo, Chao; Gao, Rui; Tian, Jun; Feng, Zuohua; Nice, Edouard C.; Sun, Jun

    2014-01-01

    Gambogic acid (GA), the main active component of gamboge resin, has potent antitumor activity both in vivo and in vitro. However, the underlying molecular mechanisms remain unclear. In this study, we found that GA could initiate autophagy in colorectal cancer cells, and inhibition of the autophagy process accelerated the effect of proliferative inhibition and apoptotic cell death induced by GA, implying a protective role of autophagy. Two-dimensional electrophoresis-based proteomics showed that GA treatment altered the expression of multiple proteins involved in redox signaling and lipid metabolism. Functional studies revealed that GA-induced dysregulation of lipid metabolism could activate 5-lipoxygenase (5-LOX), resulting in intracellular ROS accumulation, followed by inhibition of Akt-mTOR signaling and autophagy initiation. Finally, results using a xenograft model suggested ROS-induced autophagy protect against the antitumor effect of GA. Taken together, these data showed new biological activities of GA against colorectal cancer underlying the protective role of ROS-induced autophagy. This study will provide valuable insights for future studies regarding the anticancer mechanisms of GA. PMID:24810758

  7. Autophagy and human diseases

    PubMed Central

    Jiang, Peidu; Mizushima, Noboru

    2014-01-01

    Autophagy is a major intracellular degradative process that delivers cytoplasmic materials to the lysosome for degradation. Since the discovery of autophagy-related (Atg) genes in the 1990s, there has been a proliferation of studies on the physiological and pathological roles of autophagy in a variety of autophagy knockout models. However, direct evidence of the connections between ATG gene dysfunction and human diseases has emerged only recently. There are an increasing number of reports showing that mutations in the ATG genes were identified in various human diseases such as neurodegenerative diseases, infectious diseases, and cancers. Here, we review the major advances in identification of mutations or polymorphisms of the ATG genes in human diseases. Current autophagy-modulating compounds in clinical trials are also summarized. PMID:24323045

  8. Autophagy and Viruses: Adversaries or Allies?

    PubMed Central

    Dong, Xiaonan; Levine, Beth

    2013-01-01

    The autophagy pathway is an essential component of host defense against viral infection, orchestrating pathogen degradation (xenophagy), innate immune signaling, and certain aspects of adaptive immunity. Single autophagy proteins or cassettes of the core autophagy machinery can also function as antiviral factors independently of the canonical autophagy pathway. Moreover, to survive and propagate within the host, viruses have evolved a variety of strategies to evade autophagic attack and manipulate the autophagy machinery for their own benefit. This Review summarizes recent advances in understanding the antiviral and proviral roles of autophagy and previously unappreciated autophagy-independent functions of autophagy-related genes. PMID:23391695

  9. Autophagy and Cancer

    PubMed Central

    Aredia, Francesca; Ortiz, Luis Miguel Guamán; Giansanti, Vincenzo; Scovassi, A. Ivana

    2012-01-01

    Autophagy is a housekeeping survival mechanism with a protective function against stress conditions. However, when stress severity or duration increases, it may promote cell death. Paradoxically, autophagy favors cancer development, since cancer cells could enhance their proliferation potential (thus becoming able to resist anticancer therapy) thanks to the energetic supply provided by organelle degradation typically driven by autophagy following a stepwise pathway. The main actors of the autophagic machinery as well as the features shared with apoptosis will be described. Special attention will be paid to the effects of autophagy manipulation. PMID:24710488

  10. Taurine protects against As2O3-induced autophagy in pancreas of rat offsprings through Nrf2/Trx pathway.

    PubMed

    Bai, Jie; Yao, Xiaofeng; Jiang, Liping; Qiu, Tianming; Liu, Shuang; Qi, Baoxu; Zheng, Yue; Kong, Yuan; Yang, Guang; Chen, Min; Liu, Xiaofang; Sun, Xiance

    2016-04-01

    Arsenic was increasingly to blame as a risk factor for type 2 diabetes mellitus. In our previous study, we had found iAs stimulated autophagic flux and caused autophagic cell death through ROS pathway in INS-1 cells. Since NF-E2-related factor 2 (Nrf2) and the thioredoxin (Trx) system was a crucial line of defense against ROS, we investigated whether Nrf2/Trx pathway contributed to As2O3-stimulated autophagy and the role of taurine in this study. After treatment with 2 mg/kg BW-8 mg/kg BW As2O3 for 57 d, the expression of Nrf2 protein was decreased significantly in offsprings' pancreas. The expression of Trx gene was decreased significantly in pancreas subsequently. Finally, the generation of reactive oxygen species stimulated autophagy in arsenic-treated pancreas. Taurine could reverse arsenic-inhibited Nrf2 and Trx and inhibit autophagy. In short, inhibition of Nrf2/Trx pathway might play an important role in the pathogenesis of arsenic-related diabetes. Taurine could serve as nutrition supplementation against arsenic-related diabetes in high arsenic exposure area. PMID:26775255

  11. Autophagy Genes Enhance Murine Gammaherpesvirus 68 Reactivation from Latency by Preventing Virus-Induced Systemic Inflammation.

    PubMed

    Park, Sunmin; Buck, Michael D; Desai, Chandni; Zhang, Xin; Loginicheva, Ekaterina; Martinez, Jennifer; Freeman, Michael L; Saitoh, Tatsuya; Akira, Shizuo; Guan, Jun-Lin; He, You-Wen; Blackman, Marcia A; Handley, Scott A; Levine, Beth; Green, Douglas R; Reese, Tiffany A; Artyomov, Maxim N; Virgin, Herbert W

    2016-01-13

    Host genes that regulate systemic inflammation upon chronic viral infection are incompletely understood. Murine gammaherpesvirus 68 (MHV68) infection is characterized by latency in macrophages, and reactivation is inhibited by interferon-γ (IFN-γ). Using a lysozyme-M-cre (LysMcre) expression system, we show that deletion of autophagy-related (Atg) genes Fip200, beclin 1, Atg14, Atg16l1, Atg7, Atg3, and Atg5, in the myeloid compartment, inhibited MHV68 reactivation in macrophages. Atg5 deficiency did not alter reactivation from B cells, and effects on reactivation from macrophages were not explained by alterations in productive viral replication or the establishment of latency. Rather, chronic MHV68 infection triggered increased systemic inflammation, increased T cell production of IFN-γ, and an IFN-γ-induced transcriptional signature in macrophages from Atg gene-deficient mice. The Atg5-related reactivation defect was partially reversed by neutralization of IFN-γ. Thus Atg genes in myeloid cells dampen virus-induced systemic inflammation, creating an environment that fosters efficient MHV68 reactivation from latency. PMID:26764599

  12. Autophagy in infection.

    PubMed

    Deretic, Vojo

    2010-04-01

    Autophagy is a ubiquitous eukaryotic cytoplasmic quality and quantity control pathway. The role of autophagy in cytoplasmic homeostasis seamlessly extends to cell-autonomous defense against intracellular microbes. Recent studies also point to fully integrated, multitiered regulatory and effector connections between autophagy and nearly all facets of innate and adaptive immunity. Autophagy in the immune system as a whole confers measured immune responses; on the flip side, suppression of autophagy can lead to inflammation and tissue damage, as evidenced by Crohn's disease predisposition polymorphisms in autophagy basal apparatus (Atg16L) and regulatory (IRGM) genes. Polymorphisms in the IRGM gene in human populations have also been linked to predisposition to tuberculosis. There are several areas of most recent growth: first, links between autophagy regulators and infectious disease predisposition in human populations; second, demonstration of a role for autophagy in infection control in vivo in animal models; third, the definition of specific antiautophagic defenses in highly evolved pathogens; and fourth, recognition of connections between the ubiquitin system and autophagy of bacteria (and interestingly mitochondria, which are incidentally organelles of bacterial evolutionary origin) via a growing list of modifier and adapter proteins including p62/SQSTM1, NDP52, Atg32, Parkin, and Nix/BNIP3L. PMID:20116986

  13. Autophagy protects human brain microvascular endothelial cells against methylglyoxal-induced injuries, reproducible in a cerebral ischemic model in diabetic rats.

    PubMed

    Fang, Lili; Li, Xue; Zhong, Yinbo; Yu, Jing; Yu, Lina; Dai, Haibin; Yan, Min

    2015-10-01

    Cerebral microvascular endothelial cells (ECs) are crucial for brain vascular repair and maintenance, but their physiological function may be impaired during ischemic stroke and diabetes. Methylglyoxal (MGO), a reactive dicarbonyl produced during glucose metabolism, could exacerbate ischemia-induced EC injury and dysfunction. We investigated the protective effect of autophagy on cultured human brain microvascular endothelial cells (HBMEC) that underwent MGO treatment. A further study was conducted to explore the underlying mechanisms of the protective effect. Autophagic activity was assessed by evaluating protein levels, using western blot. 3-methyladenine (3-MA), bafilomycin A1, ammonium chloride (AC), Beclin 1 siRNA, and chloroquine (CQ) were used to cause autophagy inhibition. Alarmar blue assay and lactate dehydrogenase release assay were used to evaluate cell viability. Streptozotocin was administered to induce type I diabetes in rats and post-permanent middle cerebral artery occlusion was performed to elicit cerebral ischemia. Blood-brain barrier permeability was also assessed. Our study found that MGO reduced HBMEC cell viability in a concentration- and time-dependent manner, and triggered the responsive autophagy activation. Autophagy inhibitors bafilomycin A1, AC, 3-MA, and BECN1 siRNA exacerbated MGO-induced HBMEC injury. FAK phosphorylation inhibitor PF573228 inhibited MGO-triggered autophagy and enhanced lactate dehydrogenase release. Meanwhile, similar autophagy activation in brain vascular ECs was observed during permanent middle cerebral artery occlusion-induced cerebral ischemia in diabetic rats, while chloroquine-induced autophagy inhibition enhanced blood-brain barrier permeability. Taken together, our study indicates that autophagy triggered by MGO defends HBMEC against injuries. PMID:26251121

  14. Cucurbitacin I Induces Protective Autophagy in Glioblastoma in Vitro and in Vivo*

    PubMed Central

    Yuan, Guang; Yan, Shao-Feng; Xue, Hao; Zhang, Ping; Sun, Jin-Tang; Li, Gang

    2014-01-01

    There is an urgent need for new therapeutic avenues to improve the outcome of patients with glioblastoma multiforme (GBM). Current studies have suggested that cucurbitacin I, a natural selective inhibitor of JAK2/STAT3, has a potent anticancer effect on a variety of cancer cell types. This study showed that autophagy and apoptosis were induced by cucurbitacin I. Exposure of GBM cells to cucurbitacin I resulted in pronounced apoptotic cell death through activating bcl-2 family proteins. Cells treatment with cucurbitacin I up-regulated Beclin 1 and triggered autophagosome formation and accumulation as well as conversion of LC3I to LC3II. Activation of the AMP-activated protein kinase/mammalian target of rapamycin/p70S6K pathway, but not the PI3K/AKT pathway, occurred in autophagy induced by cucurbitacin I, which was accompanied by decreased hypoxia-inducible factor 1α. Stable overexpression of hypoxia-inducible factor 1α induced by FG-4497 prevented cucurbitacin I-induced autophagy and down-regulation of bcl-2. Knockdown of beclin 1 or treatment with the autophagy inhibitor 3-methyladenine also inhibited autophagy induced by cucurbitacin I. A coimmunoprecipitation assay showed that the interaction of Bcl-2 and Beclin 1/hVps34 decreased markedly in cells treated with cucurbitacin I. Furthermore, knockdown of beclin 1 or treatment with the lysosome inhibitor chloroquine sensitized cancer cells to cucurbitacin I-induced apoptosis. Finally, a xenograft model provided additional evidence for the occurrence of cucurbitacin I-induced apoptosis and autophagy in vitro. Our findings provide new insights into the molecular mechanisms underlying cucurbitacin I-mediated GBM cell death and may provide an efficacious therapy for patients harboring GBM. PMID:24599950

  15. Involvement of autophagy in ovarian cancer: a working hypothesis

    PubMed Central

    2012-01-01

    Autophagy is a lysosomal-driven catabolic process that contributes to preserve cell and tissue homeostases through the regular elimination of damaged, aged and redundant self-constituents. In normal cells, autophagy protects from DNA mutation and carcinogenesis by preventive elimination of pro-oxidative mitochondria and protein aggregates. Mutations in oncogenes and oncosuppressor genes dysregulate autophagy. Up-regulated autophagy may confer chemo- and radio-resistance to cancer cells, and also a pro-survival advantage in cancer cells experiencing oxygen and nutrient shortage. This fact is the rationale for using autophagy inhibitors along with anti-neoplastic therapies. Yet, aberrant hyper-induction of autophagy can lead to cell death, and this phenomenon could also be exploited for cancer therapy. The actual level of autophagy in the cancer cell is greatly affected by vascularization, inflammation, and stromal cell infiltration. In addition, small non-coding microRNAs have recently emerged as important epigenetic modulators of autophagy. The present review focuses on the potential involvement of macroautophagy, and on its genetic and epigenetic regulation, in ovarian cancer pathogenesis and progression. PMID:22974323

  16. Enhancing Autophagy with Drugs or Lung-directed Gene Therapy Reverses the Pathological Effects of Respiratory Epithelial Cell Proteinopathy.

    PubMed

    Hidvegi, Tunda; Stolz, Donna B; Alcorn, John F; Yousem, Samuel A; Wang, Jieru; Leme, Adriana S; Houghton, A McGarry; Hale, Pamela; Ewing, Michael; Cai, Houming; Garchar, Evelyn Akpadock; Pastore, Nunzia; Annunziata, Patrizia; Kaminski, Naftali; Pilewski, Joseph; Shapiro, Steven D; Pak, Stephen C; Silverman, Gary A; Brunetti-Pierri, Nicola; Perlmutter, David H

    2015-12-11

    Recent studies have shown that autophagy mitigates the pathological effects of proteinopathies in the liver, heart, and skeletal muscle but this has not been investigated for proteinopathies that affect the lung. This may be due at least in part to the lack of an animal model robust enough for spontaneous pathological effects from proteinopathies even though several rare proteinopathies, surfactant protein A and C deficiencies, cause severe pulmonary fibrosis. In this report we show that the PiZ mouse, transgenic for the common misfolded variant α1-antitrypsin Z, is a model of respiratory epithelial cell proteinopathy with spontaneous pulmonary fibrosis. Intracellular accumulation of misfolded α1-antitrypsin Z in respiratory epithelial cells of the PiZ model resulted in activation of autophagy, leukocyte infiltration, and spontaneous pulmonary fibrosis severe enough to elicit functional restrictive deficits. Treatment with autophagy enhancer drugs or lung-directed gene transfer of TFEB, a master transcriptional activator of the autophagolysosomal system, reversed these proteotoxic consequences. We conclude that this mouse is an excellent model of respiratory epithelial proteinopathy with spontaneous pulmonary fibrosis and that autophagy is an important endogenous proteostasis mechanism and an attractive target for therapy. PMID:26494620

  17. Enhanced autophagy ameliorates cardiac proteinopathy

    PubMed Central

    Bhuiyan, Md. Shenuarin; Pattison, J. Scott; Osinska, Hanna; James, Jeanne; Gulick, James; McLendon, Patrick M.; Hill, Joseph A.; Sadoshima, Junichi; Robbins, Jeffrey

    2013-01-01

    Basal autophagy is a crucial mechanism in cellular homeostasis, underlying both normal cellular recycling and the clearance of damaged or misfolded proteins, organelles and aggregates. We showed here that enhanced levels of autophagy induced by either autophagic gene overexpression or voluntary exercise ameliorated desmin-related cardiomyopathy (DRC). To increase levels of basal autophagy, we generated an inducible Tg mouse expressing autophagy-related 7 (Atg7), a critical and rate-limiting autophagy protein. Hearts from these mice had enhanced autophagy, but normal morphology and function. We crossed these mice with CryABR120G mice, a model of DRC in which autophagy is significantly attenuated in the heart, to test the functional significance of autophagy activation in a proteotoxic model of heart failure. Sustained Atg7-induced autophagy in the CryABR120G hearts decreased interstitial fibrosis, ameliorated ventricular dysfunction, decreased cardiac hypertrophy, reduced intracellular aggregates and prolonged survival. To determine whether different methods of autophagy upregulation have additive or even synergistic benefits, we subjected the autophagy-deficient CryABR120G mice and the Atg7-crossed CryABR120G mice to voluntary exercise, which also upregulates autophagy. The entire exercised Atg7-crossed CryABR120G cohort survived to 7 months. These findings suggest that activating autophagy may be a viable therapeutic strategy for improving cardiac performance under proteotoxic conditions. PMID:24177425

  18. Cationic poly(amidoamine) dendrimers induced cyto-protective autophagy in hepatocellular carcinoma cells

    NASA Astrophysics Data System (ADS)

    Li, Yubin; Wang, Shaofei; Wang, Ziyu; Qian, Xiaolu; Fan, Jiajun; Zeng, Xian; Sun, Yun; Song, Ping; Feng, Meiqing; Ju, Dianwen

    2014-09-01

    Poly(amidoamine) (PAMAM) dendrimers are proposed as one of the most promising nanomaterials for biomedical applications because of their unique tree-like structure, monodispersity and tunable properties. In this study, we found that PAMAM dendrimers could induce the formation of autophagosomes and the conversion of microtubule-associated protein 1 light chain 3 (LC3) in hepatocellular carcinoma HepG2 cells, while the inhibition of the Akt/mTOR and activation of the Erk 1/2 signaling pathways were involved in autophagy-induced by PAMAM dendrimers. We also investigated the suppression of autophagy with the obviously enhanced cytotoxicity of PAMAM dendrimers. Moreover, the blockage of a reactive oxygen species (ROS) could enhance the growth inhibition and apoptosis of hepatocellular carcinoma cells, induced by PAMAM dendrimers through reducing autophagic effects. Taken together, these findings explored the role and mechanism of autophagy induced by PAMAM dendrimers in HepG2 cells, provided new insight into the effect of autophagy on drug delivery nanomaterials and tumor cells and contributed to the use of a drug delivery vehicle for hepatocellular carcinoma treatment.

  19. Autophagy and protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2 alpha kinase (eIF2α) pathway protect ovarian cancer cells from metformin-induced apoptosis.

    PubMed

    Moon, Hee-Sun; Kim, Boyun; Gwak, HyeRan; Suh, Dong Hoon; Song, Yong Sang

    2016-04-01

    Metformin, an oral biguanide for the treatment of type II diabetes, has been shown to have anticancer effects in ovarian cancer. Energy starvation induced by metformin causes endoplasmic reticulum stress-mediated unfolded protein response (UPR) and autophagy. UPR and autophagy act as a survival or death mechanism in cells. In this study, we observed that metformin-induced apoptosis was relieved by autophagy and the PERK/eIF2α pathway in ovarian cancer cells, but not in peripheral blood mononuclear cells (PBMC) or 'normal' ovarian surface epithelial cells (OSE). Increased PARP cleavage and increased LC3B-II with ATG5-ATG12 complex suggested the induction of apoptosis and autophagy, respectively, in metformin-treated ovarian cancer cells. Accumulation of acidic vacuoles in the cytoplasm and downregulation of p62 further supported late-stage autophagy. Interestingly, metformin induced interdependent activation between autophagy and the UPR, especially the PERK/eIF2α pathway. Inhibition of autophagy-induced PERK inhibition, and vice versa, were demonstrated using small molecular inhibitors (PERK inhibitor I, GSK2606414; autophagy inhibitor, 3-MA, and BafA1). Moreover, autophagy and PERK activation protected ovarian cancer cells against metformin-induced apoptosis. Metformin treatment in the presence of inhibitors of PERK and autophagy, however, had no cytotoxic effects on OSE or PBMC. In conclusion, these results suggest that inhibition of autophagy and PERK can enhance the selective anticancer effects of metformin on ovarian cancer cells. © 2015 Wiley Periodicals, Inc. PMID:25663310

  20. Autophagy in colorectal cancer: An important switch from physiology to pathology

    PubMed Central

    Burada, Florin; Nicoli, Elena Raluca; Ciurea, Marius Eugen; Uscatu, Daniel Constantin; Ioana, Mihai; Gheonea, Dan Ionut

    2015-01-01

    Colorectal cancer (CRC) remains a leading cause of cancer death in both men and women worldwide. Among the factors and mechanisms that are involved in the multifactorial etiology of CRC, autophagy is an important transformational switch that occurs when a cell shifts from normal to malignant. In recent years, multiple hypotheses have been considered regarding the autophagy mechanisms that are involved in cancer. The currently accepted hypothesis is that autophagy has dual and contradictory roles in carcinogenesis, but the precise mechanisms leading to autophagy in cancer are not yet fully defined and seem to be context dependent. Autophagy is a surveillance mechanism used by normal cells that protects them from the transformation to malignancy by removing damaged organelles and aggregated proteins and by reducing reactive oxygen species, mitochondrial abnormalities and DNA damage. However, autophagy also supports tumor formation by promoting access to nutrients that are critical to the metabolism and growth of tumor cells and by inhibiting cellular death and increasing drug resistance. Autophagy studies in CRC have focused on several molecules, mainly microtubule-associated protein 1 light chain 3, beclin 1, and autophagy related 5, with conflicting results. Beneficial effects were observed for some agents that modulate autophagy in CRC either alone or, more often, in combination with other agents. More extensive studies are needed in the future to clarify the roles of autophagy-related genes and modulators in colorectal carcinogenesis, and to develop potential beneficial agents for the prognosis and treatment of CRC. PMID:26600927

  1. Intestinal Epithelium and Autophagy: Partners in Gut Homeostasis

    PubMed Central

    Randall-Demllo, Sarron; Chieppa, Marcello; Eri, Rajaraman

    2013-01-01

    One of the most significant challenges of cell biology is to understand how each type of cell copes with its specific workload without suffering damage. Among the most intriguing questions concerns intestinal epithelial cells in mammals; these cells act as a barrier between the internally protected region and the external environment that is exposed constantly to food and microbes. A major process involved in the processing of microbes is autophagy. In the intestine, through multiple, complex signaling pathways, autophagy including macroautophagy and xenophagy is pivotal in mounting appropriate intestinal immune responses and anti-microbial protection. Dysfunctional autophagy mechanism leads to chronic intestinal inflammation, such as inflammatory bowel disease (IBD). Studies involving a number of in vitro and in vivo mouse models in addition to human clinical studies have revealed a detailed role for autophagy in the generation of chronic intestinal inflammation. A number of genome-wide association studies identified roles for numerous autophagy genes in IBD, especially in Crohn’s disease. In this review, we will explore in detail the latest research linking autophagy to intestinal homeostasis and how alterations in autophagy pathways lead to intestinal inflammation. PMID:24137160

  2. Autophagy Plays a Protective Role in Tumor Necrosis Factor-α-Induced Apoptosis of Bone Marrow-Derived Mesenchymal Stem Cells.

    PubMed

    Yang, Rui; Ouyang, Yi; Li, Weiping; Wang, Peng; Deng, Haiquan; Song, Bin; Hou, Jingyi; Chen, Zhong; Xie, Zhongyu; Liu, Zhenhua; Li, Jinteng; Cen, Shuizhong; Wu, Yanfeng; Shen, Huiyong

    2016-05-15

    Bone marrow-derived mesenchymal stem cells (BMSCs) are being broadly investigated for treating numerous inflammatory diseases. However, the low survival rate of BMSCs during the transplantation process has limited their application. Autophagy can maintain cellular homeostasis and protect cells against environmental stresses. Tumor necrosis factor-α (TNF-α) is an important inflammatory cytokine that can induce both autophagy and apoptosis of BMSCs. However, the actual role of autophagy in TNF-α-induced apoptosis of BMSCs remains poorly understood. In the current study, BMSCs were treated with TNF-α/cycloheximide (CHX), and cell death was examined by the Cell Counting Kit-8, Hoechst 33342 staining, and flow cytometric analysis as well as by the level of caspase-3 and caspase-8. Meanwhile, autophagic flux was examined by analyzing the level of microtubule-associated protein light chain 3 B (LC3B)-II and SQSTEM1/p62 and by examining the amount of green fluorescent protein-LC3B by fluorescence microscopy. Then, the cell death and autophagic flux of BMSCs were examined after pretreatment and cotreatment with 3-methyladenine (3-MA, autophagy inhibitor) or rapamycin (Rap, autophagy activator) together with TNF-α/CHX. Moreover, BMSCs pretreated with lentiviruses encoding short hairpin RNA of beclin-1 (BECN1) were treated with TNF-α/CHX, and then cell death and autophagic flux were detected. We showed that BMSCs treated with TNF-α/CHX presented dramatically elevated autophagic flux and cell death. Furthermore, we showed that 3-MA and shBECN1 treatment accelerated TNF-α/CHX-induced apoptosis, but that Rap treatment ameliorated cell death. Our results demonstrate that autophagy protects BMSCs against TNF-α-induced apoptosis. Enhancing the autophagy of BMSCs may elevate cellular survival in an inflammatory microenvironment. PMID:26985709

  3. Nobiletin Induces Protective Autophagy Accompanied by ER-Stress Mediated Apoptosis in Human Gastric Cancer SNU-16 Cells.

    PubMed

    Moon, Jeong Yong; Cho, Somi Kim

    2016-01-01

    Nobiletin, a major component of citrus fruits, is a polymethoxyflavone derivative that exhibits anticancer activity against several forms of cancer, including SNU-16 human gastric cancer cells. To explore the nobiletin-induced cell death mechanism, we examined the changes in protein expression caused by nobiletin in human gastric cancer SNU-16 cells by means of two-dimensional gel electrophoresis (2-DGE), followed by peptide mass fingerprinting (PMF) analysis. Seventeen of 20 selected protein spots were successfully identified, including nine upregulated and eight downregulated proteins. In nobiletin-treated SNU-16 cells the glucose-regulated protein 78 kDa (GRP78) mRNA level was induced most significantly among six proteins related to cell survival and death. Western blot analysis was used to confirm the expression of GRP78 protein. We detected increases in the levels of the ER-stress related proteins inositol requiring enzyme 1 alpha (IRE1-α), activating transcription factor 4 (ATF-4), and C/EBP homology protein (CHOP), as well as GRP78, in response to nobiletin in SNU-16 cells. Furthermore, the ER stress-mediated apoptotic protein caspase-4 was proteolytically activated by nobiletin. Pretreatment with chloroquine, an autophagy inhibitor, strongly augmented apoptosis in SNU-16 cells, as evidenced by decreased cell viability, an increased number of sub-G1 phase cells and increased levels of cleaved PARP. Our results suggest that nobiletin-induced apoptosis in SNU-16 cells is mediated by pathways involving intracellular ER stress-mediated protective autophagy. Thus, the combination of nobiletin and an autophagy inhibitor could be a promising treatment for gastric cancer patients. PMID:27428937

  4. p62/Sequestosome-1, Autophagy-related Gene 8, and Autophagy in Drosophila Are Regulated by Nuclear Factor Erythroid 2-related Factor 2 (NRF2), Independent of Transcription Factor TFEB*

    PubMed Central

    Jain, Ashish; Rusten, Tor Erik; Katheder, Nadja; Elvenes, Julianne; Bruun, Jack-Ansgar; Sjøttem, Eva; Lamark, Trond; Johansen, Terje

    2015-01-01

    The selective autophagy receptor p62/sequestosome 1 (SQSTM1) interacts directly with LC3 and is involved in oxidative stress signaling in two ways in mammals. First, p62 is transcriptionally induced upon oxidative stress by the NF-E2-related factor 2 (NRF2) by direct binding to an antioxidant response element in the p62 promoter. Second, p62 accumulation, occurring when autophagy is impaired, leads to increased p62 binding to the NRF2 inhibitor KEAP1, resulting in reduced proteasomal turnover of NRF2. This gives chronic oxidative stress signaling through a feed forward loop. Here, we show that the Drosophila p62/SQSTM1 orthologue, Ref(2)P, interacts directly with DmAtg8a via an LC3-interacting region motif, supporting a role for Ref(2)P in selective autophagy. The ref(2)P promoter also contains a functional antioxidant response element that is directly bound by the NRF2 orthologue, CncC, which can induce ref(2)P expression along with the oxidative stress-associated gene gstD1. However, distinct from the situation in mammals, Ref(2)P does not interact directly with DmKeap1 via a KEAP1-interacting region motif; nor does ectopically expressed Ref(2)P or autophagy deficiency activate the oxidative stress response. Instead, DmAtg8a interacts directly with DmKeap1, and DmKeap1 is removed upon programmed autophagy in Drosophila gut cells. Strikingly, CncC induced increased Atg8a levels and autophagy independent of TFEB/MitF in fat body and larval gut tissues. Thus, these results extend the intimate relationship between oxidative stress-sensing NRF2/CncC transcription factors and autophagy and suggest that NRF2/CncC may regulate autophagic activity in other organisms too. PMID:25931115

  5. Mature adipocytes in bone marrow protect myeloma cells against chemotherapy through autophagy activation.

    PubMed

    Liu, Zhiqiang; Xu, Jingda; He, Jin; Liu, Huan; Lin, Pei; Wan, Xinhai; Navone, Nora M; Tong, Qiang; Kwak, Larry W; Orlowski, Robert Z; Yang, Jing

    2015-10-27

    A major problem in patients with multiple myeloma is chemotherapy resistance, which develops in myeloma cells upon interaction with bone marrow stromal cells. However, few studies have determined the role of bone marrow adipocytes, a major component of stromal cells in the bone marrow, in myeloma chemotherapy resistance. We reveal that mature human adipocytes activate autophagy and upregulate the expression of autophagic proteins, thereby suppressing chemotherapy-induced caspase cleavage and apoptosis in myeloma cells. We found that adipocytes secreted known and novel adipokines, such as leptin and adipsin. The addition of these adipokines enhanced the expression of autophagic proteins and reduced apoptosis in myeloma cells. In vivo studies further demonstrated the importance of bone marrow-derived adipocytes in the reduced response of myeloma cells to chemotherapy. Our findings suggest that adipocytes, adipocyte-secreted adipokines, and adipocyte-activated autophagy are novel targets for combatting chemotherapy resistance and enhancing treatment efficacy in myeloma patients. PMID:26455377

  6. Dysregulation of Autophagy, Mitophagy, and Apoptotic Genes in the Medial Temporal Lobe Cortex in an Ischemic Model of Alzheimer's Disease.

    PubMed

    Ułamek-Kozioł, Marzena; Kocki, Janusz; Bogucka-Kocka, Anna; Petniak, Alicja; Gil-Kulik, Paulina; Januszewski, Sławomir; Bogucki, Jacek; Jabłoński, Mirosław; Furmaga-Jabłońska, Wanda; Brzozowska, Judyta; Czuczwar, Stanisław J; Pluta, Ryszard

    2016-07-27

    Ischemic brain damage is a pathological incident that is often linked with medial temporal lobe cortex injury and finally its atrophy. Post-ischemic brain injury associates with poor prognosis since neurons of selectively vulnerable ischemic brain areas are disappearing by apoptotic program of neuronal death. Autophagy has been considered, after brain ischemia, as a guardian against neurodegeneration. Consequently, we have examined changes in autophagy (BECN 1), mitophagy (BNIP 3), and apoptotic (caspase 3) genes in the medial temporal lobe cortex with the use of quantitative reverse-transcriptase PCR following transient 10-min global brain ischemia in rats with survival 2, 7, and 30 days. The intense significant overexpression of BECN 1 gene was noted on the 2nd day, while on days 7-30 the expression of this gene was still upregulated. BNIP 3 gene was downregulated on the 2nd day, but on days 7-30 post-ischemia, there was a significant reverse tendency. Caspase 3 gene, associated with apoptotic neuronal death, was induced in the same way as BNIP 3 gene after brain ischemia. Thus, the demonstrated changes indicate that the considerable dysregulation of expression of BECN 1, BNIP 3, and caspase 3 genes may be connected with a response of neuronal cells in medial temporal lobe cortex to transient complete brain ischemia. PMID:27472881

  7. Immunologic manifestations of autophagy

    PubMed Central

    Deretic, Vojo; Kimura, Tomonori; Timmins, Graham; Moseley, Pope; Chauhan, Santosh; Mandell, Michael

    2015-01-01

    The broad immunologic roles of autophagy span innate and adaptive immunity and are often manifested in inflammatory diseases. The immune effects of autophagy partially overlap with its roles in metabolism and cytoplasmic quality control but typically expand further afield to encompass unique immunologic adaptations. One of the best-appreciated manifestations of autophagy is protection against microbial invasion, but this is by no means limited to direct elimination of intracellular pathogens and includes a stratified array of nearly all principal immunologic processes. This Review summarizes the broad immunologic roles of autophagy. Furthermore, it uses the autophagic control of Mycobacterium tuberculosis as a paradigm to illustrate the breadth and complexity of the immune effects of autophagy. PMID:25654553

  8. Bexarotene targets autophagy and is protective against thromboembolic stroke in aged mice with tauopathy.

    PubMed

    Huuskonen, Mikko T; Loppi, Sanna; Dhungana, Hiramani; Keksa-Goldsteine, Velta; Lemarchant, Sighild; Korhonen, Paula; Wojciechowski, Sara; Pollari, Eveliina; Valonen, Piia; Koponen, Juho; Takashima, Akihiko; Landreth, Gary; Goldsteins, Gundars; Malm, Tarja; Koistinaho, Jari; Kanninen, Katja M

    2016-01-01

    Stroke is a highly debilitating, often fatal disorder for which current therapies are suitable for only a minor fraction of patients. Discovery of novel, effective therapies is hampered by the fact that advanced age, primary age-related tauopathy or comorbidities typical to several types of dementing diseases are usually not taken into account in preclinical studies, which predominantly use young, healthy rodents. Here we investigated for the first time the neuroprotective potential of bexarotene, an FDA-approved agent, in a co-morbidity model of stroke that combines high age and tauopathy with thromboembolic cerebral ischemia. Following thromboembolic stroke bexarotene enhanced autophagy in the ischemic brain concomitantly with a reduction in lesion volume and amelioration of behavioral deficits in aged transgenic mice expressing the human P301L-Tau mutation. In in vitro studies bexarotene increased the expression of autophagy markers and reduced autophagic flux in neuronal cells expressing P301L-Tau. Bexarotene also restored mitochondrial respiration deficits in P301L-Tau neurons. These newly described actions of bexarotene add to the growing amount of compelling data showing that bexarotene is a potent neuroprotective agent, and identify a novel autophagy-modulating effect of bexarotene. PMID:27624652

  9. The role of autophagy in the intracellular survival of Campylobacter concisus

    PubMed Central

    Burgos-Portugal, Jose A.; Mitchell, Hazel M.; Castaño-Rodríguez, Natalia; Kaakoush, Nadeem O.

    2014-01-01

    Campylobacter concisus is an emerging pathogen that has been associated with gastrointestinal diseases. Given the importance of autophagy for the elimination of intracellular bacteria and the subversion of this process by pathogenic bacteria, we investigated the role of autophagy in C. concisus intracellular survival. Gentamicin protection assays were employed to assess intracellular levels of C. concisus within Caco-2 cells, following autophagy induction and inhibition. To assess the interaction between C. concisus and autophagosomes, confocal microscopy, scanning electron microscopy, and transmission electron microscopy were employed. Expression levels of 84 genes involved in the autophagy process were measured using qPCR. Autophagy inhibition resulted in two- to four-fold increases in intracellular levels of C. concisus within Caco-2 cells, while autophagy induction resulted in a significant reduction in intracellular levels or bacterial clearance. C. concisus strains with low intracellular survival levels showed a dramatic increase in these levels upon autophagy inhibition. Confocal microscopy showed co-localization of the bacterium with autophagosomes, while transmission electron microscopy identified intracellular bacteria persisting within autophagic vesicles. Further, qPCR showed that following infection, 13 genes involved in the autophagy process were significantly regulated, and a further five showed borderline results, with an overall indication towards a dampening effect exerted by the bacterium on this process. Our data collectively indicates that while autophagy is important for the clearance of C. concisus, some strains may manipulate this process to benefit their intracellular survival. PMID:24918042

  10. Mycobacterium tuberculosis EIS gene inhibits macrophage autophagy through up-regulation of IL-10 by increasing the acetylation of histone H3.

    PubMed

    Duan, Liang; Yi, Min; Chen, Juan; Li, Shengjin; Chen, Weixian

    2016-05-13

    Autophagy plays a crucial role in the progress of Mycobacterium tuberculosis (MTB) infection. Recently, MTB enhanced intracellular survival (EIS) protein was reported to be secreted from MTB cells and linked to the inhibition of autophagy and the intracellular persistence of the pathogen. Here, we investigated the mechanism of EIS-mediated inhibition of autophagy in a human phorbol myristate acetate (PMA)-treated THP-1 cell line as well as in murine macrophages. We confirmed that the presence of EIS led to the inhibition of rapamycin (Rapa)-induced autophagy, while IL-10 gene expression was increased and Akt/mTOR/p70S6K pathway was activated during the process. IL-10 gene silencing led to a significant recovery of EIS-mediated autophagy suppression and decreased activity of the Akt/mTOR/p70S6K pathway. IL-10 promoter activity was unaffected by EIS. Remarkably, EIS increased the acetylation level of histone H3 (Ac-H3), which binds to the SP1 and STAT3 region of the human IL-10 gene promoter sequence. Thus, EIS protein possibly increased IL-10 expression through the regulation of Ac-H3 of its promoter. Our data demonstrated that one possible mechanism of the MTB evasion of autophagy is that the EIS protein up-regulates IL-10 via Ac-H3 and thus activates Akt/mTOR/p70S6K pathway. PMID:27079235

  11. Identification of Autophagy in the Pine Wood Nematode Bursaphelenchus xylophilus and the Molecular Characterization and Functional Analysis of Two Novel Autophagy-Related Genes, BxATG1 and BxATG8.

    PubMed

    Deng, Li-Na; Wu, Xiao-Qin; Ye, Jian-Ren; Xue, Qi

    2016-01-01

    The pine wood nematode, Bursaphelenchus xylophilus, causes huge economic losses in pine forests, has a complex life cycle, and shows the remarkable ability to survive under unfavorable and changing environmental conditions. This ability may be related to autophagy, which is still poorly understood in B. xylophilus and no autophagy-related genes have been previously characterized. In this study, transmission electron microscopy was used to confirm that autophagy exists in B. xylophilus. The full-length cDNAs of BxATG1 and BxATG8 were first cloned from B. xylophilus, and BxATG1 and BxATG8 were characterized using bioinformatics methods. The expression pattern of the autophagy marker BxATG8 was investigated using in situ hybridization (ISH). BxATG8 was expressed in esophageal gland and hypodermal seam cells. We tested the effects of RNA interference (RNAi) on BxATG1 and BxATG8. The results revealed that BxATG1 and BxATG8 were likely associated with propagation of nematodes on fungal mats. This study confirmed the molecular characterization and functions of BxATG1 and BxATG8 in B. xylophilus and provided fundamental information between autophagy and B. xylophilus. PMID:26950119

  12. Identification of Autophagy in the Pine Wood Nematode Bursaphelenchus xylophilus and the Molecular Characterization and Functional Analysis of Two Novel Autophagy-Related Genes, BxATG1 and BxATG8

    PubMed Central

    Deng, Li-Na; Wu, Xiao-Qin; Ye, Jian-Ren; Xue, Qi

    2016-01-01

    The pine wood nematode, Bursaphelenchus xylophilus, causes huge economic losses in pine forests, has a complex life cycle, and shows the remarkable ability to survive under unfavorable and changing environmental conditions. This ability may be related to autophagy, which is still poorly understood in B. xylophilus and no autophagy-related genes have been previously characterized. In this study, transmission electron microscopy was used to confirm that autophagy exists in B. xylophilus. The full-length cDNAs of BxATG1 and BxATG8 were first cloned from B. xylophilus, and BxATG1 and BxATG8 were characterized using bioinformatics methods. The expression pattern of the autophagy marker BxATG8 was investigated using in situ hybridization (ISH). BxATG8 was expressed in esophageal gland and hypodermal seam cells. We tested the effects of RNA interference (RNAi) on BxATG1 and BxATG8. The results revealed that BxATG1 and BxATG8 were likely associated with propagation of nematodes on fungal mats. This study confirmed the molecular characterization and functions of BxATG1 and BxATG8 in B. xylophilus and provided fundamental information between autophagy and B. xylophilus. PMID:26950119

  13. Cucurbitacin E induces caspase-dependent apoptosis and protective autophagy mediated by ROS in lung cancer cells.

    PubMed

    Ma, Guixin; Luo, Weiwei; Lu, Jinjian; Ma, Dik-Lung; Leung, Chung-Hang; Wang, Yitao; Chen, Xiuping

    2016-06-25

    Cucurbitacin E (CuE) is a triterpenoid with potent anticancer activities while the underlying mechanisms remain elusive. In the present study, the anticancer effects of CuE on 95D lung cancer cells were investigated. CuE decreased cell viability, inhibited colony formation, and increased reactive oxygen species (ROS) in a concentration-dependent manner, which were reversed by N-acetyl-l-cysteine (NAC). CuE induced apoptosis as determined by JC-1 staining, expression of Bcl-2 family proteins, cleavage of caspases, and TUNEL staining. NAC and Ac-DEVD-CHO partially reversed CuE-induced cleavage of caspase-3, caspase-7, and PARP. Furthermore, CuE caused accumulation of autophagic vacuoles and concentration- and time-dependent expression of LC3II protein. Autophagy inhibitors chloroquine and bafilomycin A1 enhanced CuE-induced LC3II expression and cell death. CuE-triggered protein expression of p-AKT, p-mTOR, Beclin-1, and p-ULK1 was partially reversed by NAC pretreatment. In addition, CuE treatment damaged F-actin without affecting β-tubulin as confirmed by immunofluorescence. In conclusion, CuE induced ROS-dependent apoptosis through Bcl-2 family and caspases in 95D lung cancer cells. Furthermore, CuE induced protective autophagy mediated by ROS through AKT/mTOR pathway. This study provides novel roles of ROS in the anticancer effect of CuE. PMID:27106530

  14. Sulforaphane protects against rotenone-induced neurotoxicity in vivo: Involvement of the mTOR, Nrf2, and autophagy pathways

    PubMed Central

    Zhou, Qian; Chen, Bin; Wang, Xindong; Wu, Lixin; Yang, Yang; Cheng, Xiaolan; Hu, Zhengli; Cai, Xueting; Yang, Jie; Sun, Xiaoyan; Lu, Wuguang; Yan, Huaijiang; Chen, Jiao; Ye, Juan; Shen, Jianping; Cao, Peng

    2016-01-01

    Sulforaphane, a naturally occurring compound found in cruciferous vegetables, has been shown to be neuroprotective in several neurological disorders. In this study, we sought to investigate the potential protective effects and associated molecular mechanisms of sulforaphane in an in vivo Parkinson’s disease (PD) model, based on rotenone-mediated neurotoxicity. Our results showed that sulforaphane inhibited rotenone-induced locomotor activity deficiency and dopaminergic neuronal loss. Additionally, sulforaphane treatment inhibited the rotenone-induced reactive oxygen species production, malondialdehyde (MDA) accumulation, and resulted in an increased level of total glutathione and reduced glutathione (GSH): oxidized glutathione (GSSG) in the brain. Western blot analysis illustrated that sulforaphane increased the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H quinone oxidoreductase (NQO1), the latter two of which are anti-oxidative enzymes. Moreover, sulforaphane treatment significantly attenuated rotenone-inhibited mTOR-mediated p70S6K and 4E-BP1 signalling pathway, as well as neuronal apoptosis. In addition, sulforaphane rescued rotenone-inhibited autophagy, as detected by LC3-II. Collectively, these findings demonstrated that sulforaphane exert neuroprotective effect involving Nrf2-dependent reductions in oxidative stress, mTOR-dependent inhibition of neuronal apoptosis, and the restoration of normal autophagy. Sulforaphane appears to be a promising compound with neuroprotective properties that may play an important role in preventing PD. PMID:27553905

  15. Sulforaphane protects against rotenone-induced neurotoxicity in vivo: Involvement of the mTOR, Nrf2, and autophagy pathways.

    PubMed

    Zhou, Qian; Chen, Bin; Wang, Xindong; Wu, Lixin; Yang, Yang; Cheng, Xiaolan; Hu, Zhengli; Cai, Xueting; Yang, Jie; Sun, Xiaoyan; Lu, Wuguang; Yan, Huaijiang; Chen, Jiao; Ye, Juan; Shen, Jianping; Cao, Peng

    2016-01-01

    Sulforaphane, a naturally occurring compound found in cruciferous vegetables, has been shown to be neuroprotective in several neurological disorders. In this study, we sought to investigate the potential protective effects and associated molecular mechanisms of sulforaphane in an in vivo Parkinson's disease (PD) model, based on rotenone-mediated neurotoxicity. Our results showed that sulforaphane inhibited rotenone-induced locomotor activity deficiency and dopaminergic neuronal loss. Additionally, sulforaphane treatment inhibited the rotenone-induced reactive oxygen species production, malondialdehyde (MDA) accumulation, and resulted in an increased level of total glutathione and reduced glutathione (GSH): oxidized glutathione (GSSG) in the brain. Western blot analysis illustrated that sulforaphane increased the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H quinone oxidoreductase (NQO1), the latter two of which are anti-oxidative enzymes. Moreover, sulforaphane treatment significantly attenuated rotenone-inhibited mTOR-mediated p70S6K and 4E-BP1 signalling pathway, as well as neuronal apoptosis. In addition, sulforaphane rescued rotenone-inhibited autophagy, as detected by LC3-II. Collectively, these findings demonstrated that sulforaphane exert neuroprotective effect involving Nrf2-dependent reductions in oxidative stress, mTOR-dependent inhibition of neuronal apoptosis, and the restoration of normal autophagy. Sulforaphane appears to be a promising compound with neuroprotective properties that may play an important role in preventing PD. PMID:27553905

  16. Genome-Wide Screen in Saccharomyces cerevisiae Identifies Vacuolar Protein Sorting, Autophagy, Biosynthetic, and tRNA Methylation Genes Involved in Life Span Regulation

    PubMed Central

    Shamalnasab, Mehrnaz; Galbani, Abdulaye; Wei, Min; Giaever, Guri; Nislow, Corey; Longo, Valter D.

    2010-01-01

    The study of the chronological life span of Saccharomyces cerevisiae, which measures the survival of populations of non-dividing yeast, has resulted in the identification of homologous genes and pathways that promote aging in organisms ranging from yeast to mammals. Using a competitive genome-wide approach, we performed a screen of a complete set of approximately 4,800 viable deletion mutants to identify genes that either increase or decrease chronological life span. Half of the putative short-/long-lived mutants retested from the primary screen were confirmed, demonstrating the utility of our approach. Deletion of genes involved in vacuolar protein sorting, autophagy, and mitochondrial function shortened life span, confirming that respiration and degradation processes are essential for long-term survival. Among the genes whose deletion significantly extended life span are ACB1, CKA2, and TRM9, implicated in fatty acid transport and biosynthesis, cell signaling, and tRNA methylation, respectively. Deletion of these genes conferred heat-shock resistance, supporting the link between life span extension and cellular protection observed in several model organisms. The high degree of conservation of these novel yeast longevity determinants in other species raises the possibility that their role in senescence might be conserved. PMID:20657825

  17. Sirtuin 3 Protects against Urban Particulate Matter-Induced Autophagy in Human Bronchial Epithelial Cells.

    PubMed

    Chen, I-Chieh; Huang, Hsin-Hsiu; Chen, Pei-Fen; Chiang, Hung-Che

    2016-07-01

    Urban particulate matter (urban PM) is a heterogeneous mixture of various types of particles originating from different sources. Exposure to high concentrations of urban PM leading to adverse health effects is evaluated by using in vitro cultures of human lung epithelial cells. However, the mechanism underlying the correlation between high concentrations of urban PM exposure and adverse health effects has not been fully elucidated; urban PM-induced oxidative stress is considered as an important mechanism of urban PM-mediated cytotoxicity. Sirtuin 3 (SIRT3), a primary mitrochondrial deacetylase, controls cellular reactive oxygen species (ROS) production, and expression of antioxidant enzymes. In this study, we examined the role of SIRT3 in the regulation of urban PM-induced oxidative stress in normal primary human bronchial epithelial cells (HBEpiCs). Cell viability showed a time- and concentration-dependent decrease when exposed to urban PM, which could indicate that the amount of lactate dehydrogenase released from the cell in response to urban PM is related to cell viability in HBEpiC. The effects of urban PM on morphological and biochemical markers of autophagy in HBEpiC were analyzed by electron microscopy and Western blotting. Overexpression of SIRT3 inhibited urban PM-induced ROS generation, while concomitantly increasing the expression of antioxidant enzymes, and decreasing NF-κB activation and release of inflammation factors. Up-regulation of SIRT3 significantly inhibited the expression of autophagy markers and autophagic vacuole formation. Our findings provide a valuable insight into the potential role of the SIRT3 enzyme in regulating urban PM-induced autophagy by mediating urban PM-induced oxidative stress, which may contribute to urban PM-induced impairment of airway epithelial cell function. PMID:27125970

  18. Exogenous NAD(+) decreases oxidative stress and protects H2O2-treated RPE cells against necrotic death through the up-regulation of autophagy.

    PubMed

    Zhu, Ying; Zhao, Ke-Ke; Tong, Yao; Zhou, Ya-Li; Wang, Yi-Xiao; Zhao, Pei-Quan; Wang, Zhao-Yang

    2016-01-01

    Increased oxidative stress, which can lead to the retinal pigment epithelium (RPE) cell death by inducing ATP depletion and DNA repair, is believed to be a prominent pathology in age-related macular degeneration (AMD). In the present study, we showed that and 0.1 mM nicotinamide adenine dinucleotide (NAD(+)) administration significantly blocked RPE cell death induced by 300 μM H2O2. Further investigation showed that H2O2 resulted in increased intracellular ROS level, activation of PARP-1 and subsequently necrotic death of RPE cells. Exogenous NAD(+) administration significantly decreased intracellular and intranuclear ROS levels in H2O2-treated RPE cells. In addition, NAD(+) administration to H2O2-treated RPE cells inhibited the activation of PARP-1 and protected the RPE cells against necrotic death. Moreover, exogenous NAD(+) administration up-regulated autophagy in the H2O2-treated RPE cells. Inhibition of autophagy by LY294002 blocked the decrease of intracellular and intranuclear ROS level. Besides, inhibition of autophagy by LY294002 abolished the protection of exogenous NAD(+) against H2O2-induced cell necrotic death. Taken together, our findings indicate that that exogenous NAD(+) administration suppresses H2O2-induced oxidative stress and protects RPE cells against PARP-1 mediated necrotic death through the up-regulation of autophagy. The results suggest that exogenous NAD(+) administration might be potential value for the treatment of AMD. PMID:27240523

  19. Exogenous NAD+ decreases oxidative stress and protects H2O2-treated RPE cells against necrotic death through the up-regulation of autophagy

    PubMed Central

    Zhu, Ying; Zhao, Ke-ke; Tong, Yao; Zhou, Ya-li; Wang, Yi-xiao; Zhao, Pei-quan; Wang, Zhao-yang

    2016-01-01

    Increased oxidative stress, which can lead to the retinal pigment epithelium (RPE) cell death by inducing ATP depletion and DNA repair, is believed to be a prominent pathology in age-related macular degeneration (AMD). In the present study, we showed that and 0.1 mM nicotinamide adenine dinucleotide (NAD+) administration significantly blocked RPE cell death induced by 300 μM H2O2. Further investigation showed that H2O2 resulted in increased intracellular ROS level, activation of PARP-1 and subsequently necrotic death of RPE cells. Exogenous NAD+ administration significantly decreased intracellular and intranuclear ROS levels in H2O2-treated RPE cells. In addition, NAD+ administration to H2O2-treated RPE cells inhibited the activation of PARP-1 and protected the RPE cells against necrotic death. Moreover, exogenous NAD+ administration up-regulated autophagy in the H2O2-treated RPE cells. Inhibition of autophagy by LY294002 blocked the decrease of intracellular and intranuclear ROS level. Besides, inhibition of autophagy by LY294002 abolished the protection of exogenous NAD+ against H2O2-induced cell necrotic death. Taken together, our findings indicate that that exogenous NAD+ administration suppresses H2O2-induced oxidative stress and protects RPE cells against PARP-1 mediated necrotic death through the up-regulation of autophagy. The results suggest that exogenous NAD+ administration might be potential value for the treatment of AMD. PMID:27240523

  20. Salmonella plasmid virulence gene spvB enhances bacterial virulence by inhibiting autophagy in a zebrafish infection model.

    PubMed

    Li, Yuan-Yuan; Wang, Ting; Gao, Song; Xu, Guang-Mei; Niu, Hua; Huang, Rui; Wu, Shu-Yan

    2016-02-01

    Salmonella enterica serovar typhimurium (S. typhimurium) is a facultative intracellular pathogen that can cause gastroenteritis and systemic infection in a wide range of hosts. Salmonella plasmid virulence gene spvB is closely related to bacterial virulence in different cells and animal models, and the encoded protein acts as an intracellular toxin required for ADP-ribosyl transferase activity. However, until now there is no report about the pathogenecity of spvB gene on zebrafish. Due to the outstanding advantages of zebrafish in analyzing bacteria-host interactions, a S. typhimurium infected zebrafish model was set up here to study the effect of spvB on autophagy and intestinal pathogenesis in vivo. We found that spvB gene could decrease the LD50 of S. typhimurium, and the strain carrying spvB promoted bacterial proliferation and aggravated the intestinal damage manifested by the narrowed intestines, fallen microvilli, blurred epithelium cell structure and infiltration of inflammatory cells. Results demonstrated the enhanced virulence induced by spvB in zebrafish. In spvB-mutant strain infected zebrafish, the levels of Lc3 turnover and Beclin1 expression increased, and the double-membraned autophagosome structures were observed, suggesting that spvB can inhibit autophagy activity. In summary, our results indicate that S. typhimurium strain containing spvB displays more virulence, triggering an increase in bacterial survival and intestine injuries by suppressing autophagy for the first time. This model provides novel insights into the role of Salmonella plasmid virulence gene in bacterial pathogenesis, and can help to further elucidate the relationship between bacteria and host immune response. PMID:26723267

  1. Analyzing autophagy in Magnaporthe oryzae.

    PubMed

    Xu, Fei; Liu, Xiao-Hong; Zhuang, Fei-Long; Zhu, Jun; Lin, Fu-Cheng

    2011-05-01

    Magnaporthe oryzae is an important plant pathogenic fungus that greatly threatens the world's food security. Both genome-wide and individual gene studies have shown that the pathogenicity of the fungus is severely dependent on the intracellular autophagy process during appressoria development. This protocol discusses a systematic methodology to discover and monitor autophagy-related (ATG) genes in M. oryzae. PMID:21317549

  2. Elevated autophagy gene expression in adipose tissue of obese humans: A potential non-cell-cycle-dependent function of E2F1

    PubMed Central

    Haim, Yulia; Blüher, Matthias; Slutsky, Noa; Goldstein, Nir; Klöting, Nora; Harman-Boehm, Ilana; Kirshtein, Boris; Ginsberg, Doron; Gericke, Martin; Guiu Jurado, Esther; Kovsan, Julia; Tarnovscki, Tanya; Kachko, Leonid; Bashan, Nava; Gepner, Yiftach; Shai, Iris; Rudich, Assaf

    2015-01-01

    Autophagy genes' expression is upregulated in visceral fat in human obesity, associating with obesity-related cardio-metabolic risk. E2F1 (E2F transcription factor 1) was shown in cancer cells to transcriptionally regulate autophagy. We hypothesize that E2F1 regulates adipocyte autophagy in obesity, associating with endocrine/metabolic dysfunction, thereby, representing non-cell-cycle function of this transcription factor. E2F1 protein (N=69) and mRNA (N=437) were elevated in visceral fat of obese humans, correlating with increased expression of ATG5 (autophagy-related 5), MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 β), but not with proliferation/cell-cycle markers. Elevated E2F1 mainly characterized the adipocyte fraction, whereas MKI67 (marker of proliferation Ki-67) was elevated in the stromal-vascular fraction of adipose tissue. In human visceral fat explants, chromatin-immunoprecipitation revealed body mass index (BMI)-correlated increase in E2F1 binding to the promoter of MAP1LC3B, but not to the classical cell cycle E2F1 target, CCND1 (cyclin D1). Clinically, omental fat E2F1 expression correlated with insulin resistance, circulating free-fatty-acids (FFA), and with decreased circulating ADIPOQ/adiponectin, associations attenuated by adjustment for autophagy genes. Overexpression of E2F1 in HEK293 cells enhanced promoter activity of several autophagy genes and autophagic flux, and sensitized to further activation of autophagy by TNF. Conversely, mouse embryonic fibroblast (MEF)-derived adipocytes from e2f1 knockout mice (e2f1−/−) exhibited lower autophagy gene expression and flux, were more insulin sensitive, and secreted more ADIPOQ. Furthermore, e2f1−/− MEF-derived adipocytes, and autophagy-deficient (by Atg7 siRNA) adipocytes were resistant to cytokines-induced decrease in ADIPOQ secretion. Jointly, upregulated E2F1 sensitizes adipose tissue autophagy to inflammatory stimuli, linking visceral obesity to adipose and systemic

  3. Autophagy gene Atg16l1 prevents lethal T cell alloreactivity mediated by dendritic cells

    PubMed Central

    Hubbard-Lucey, Vanessa M.; Shono, Yusuke; Maurer, Katie; West, Mallory L.; Singer, Natalie V.; Ziegler, Carly G. K.; Lezcano, Cecilia; Motta, Ana Carolina Fragoso; Schmid, Karin; Levi, Samuel M.; Murphy, George F.; Liu, Chen; Winkler, Jeffrey D.; Amaravadi, Ravi K.; Rogler, Gerhard; Dickinson, Anne M.; Holler, Ernst; van den Brink, Marcel RM; Cadwell, Ken

    2014-01-01

    SUMMARY Atg16L1 mediates the cellular degradative process of autophagy and is considered a critical regulator of inflammation based on its genetic association with inflammatory bowel disease. Here we find that Atg16L1 deficiency leads to an exacerbated graft-versus-host disease (GVHD) in a mouse model of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Atg16L1-deficient allo-HSCT recipients with GVHD displayed increased T cell proliferation due to increased dendritic cell (DC) numbers and co-stimulatory molecule expression. Reduced autophagy within DCs was associated with lysosomal abnormalities and decreased amounts of A20, a negative regulator of DC activation. These results broaden the function of Atg16L1 and the autophagy pathway to include a role in limiting a DC-mediated response during inflammatory disease, such as GVHD. PMID:25308334

  4. Autophagy gene Atg16L1 prevents lethal T cell alloreactivity mediated by dendritic cells.

    PubMed

    Hubbard-Lucey, Vanessa M; Shono, Yusuke; Maurer, Katie; West, Mallory L; Singer, Natalie V; Ziegler, Carly G K; Lezcano, Cecilia; Motta, Ana Carolina Fragoso; Schmid, Karin; Levi, Samuel M; Murphy, George F; Liu, Chen; Winkler, Jeffrey D; Amaravadi, Ravi K; Rogler, Gerhard; Dickinson, Anne M; Holler, Ernst; van den Brink, Marcel R M; Cadwell, Ken

    2014-10-16

    Atg16L1 mediates the cellular degradative process of autophagy and is considered a critical regulator of inflammation based on its genetic association with inflammatory bowel disease. Here we find that Atg16L1 deficiency leads to an exacerbated graft-versus-host disease (GVHD) in a mouse model of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Atg16L1-deficient allo-HSCT recipients with GVHD displayed increased T cell proliferation due to increased dendritic cell (DC) numbers and costimulatory molecule expression. Reduced autophagy within DCs was associated with lysosomal abnormalities and decreased amounts of A20, a negative regulator of DC activation. These results broaden the function of Atg16L1 and the autophagy pathway to include a role in limiting a DC-mediated response during inflammatory disease, such as GVHD. PMID:25308334

  5. Historical landmarks of autophagy research.

    PubMed

    Ohsumi, Yoshinori

    2014-01-01

    The year of 2013 marked the 50th anniversary of C de Duve's coining of the term "autophagy" for the degradation process of cytoplasmic constituents in the lysosome/vacuole. This year we regretfully lost this great scientist, who contributed much during the early years of research to the field of autophagy. Soon after the discovery of lysosomes by de Duve, electron microscopy revealed autophagy as a means of delivering intracellular components to the lysosome. For a long time after the discovery of autophagy, studies failed to yield any significant advances at a molecular level in our understanding of this fundamental pathway of degradation. The first breakthrough was made in the early 1990s, as autophagy was discovered in yeast subjected to starvation by microscopic observation. Next, a genetic effort to address the poorly understood problem of autophagy led to the discovery of many autophagy-defective mutants. Subsequent identification of autophagy-related genes in yeast revealed unique sets of molecules involved in membrane dynamics during autophagy. ATG homologs were subsequently found in various organisms, indicating that the fundamental mechanism of autophagy is well conserved among eukaryotes. These findings brought revolutionary changes to research in this field. For instance, the last 10 years have seen remarkable progress in our understanding of autophagy, not only in terms of the molecular mechanisms of autophagy, but also with regard to its broad physiological roles and relevance to health and disease. Now our knowledge of autophagy is dramatically expanding day by day. Here, the historical landmarks underpinning the explosion of autophagy research are described with a particular focus on the contribution of yeast as a model organism. PMID:24366340

  6. Cathepsin D protects colorectal cancer cells from acetate-induced apoptosis through autophagy-independent degradation of damaged mitochondria

    PubMed Central

    Oliveira, C S F; Pereira, H; Alves, S; Castro, L; Baltazar, F; Chaves, S R; Preto, A; Côrte-Real, M

    2015-01-01

    Acetate is a short-chain fatty acid secreted by Propionibacteria from the human intestine, known to induce mitochondrial apoptotic death in colorectal cancer (CRC) cells. We previously established that acetate also induces lysosome membrane permeabilization in CRC cells, associated with release of the lysosomal protease cathepsin D (CatD), which has a well-established role in the mitochondrial apoptotic cascade. Unexpectedly, we showed that CatD has an antiapoptotic role in this process, as pepstatin A (a CatD inhibitor) increased acetate-induced apoptosis. These results mimicked our previous data in the yeast system showing that acetic acid activates a mitochondria-dependent apoptosis process associated with vacuolar membrane permeabilization and release of the vacuolar protease Pep4p, ortholog of mammalian CatD. Indeed, this protease was required for cell survival in a manner dependent on its catalytic activity and for efficient mitochondrial degradation independently of autophagy. In this study, we therefore assessed the role of CatD in acetate-induced mitochondrial alterations. We found that, similar to acetic acid in yeast, acetate-induced apoptosis is not associated with autophagy induction in CRC cells. Moreover, inhibition of CatD with small interfering RNA or pepstatin A enhanced apoptosis associated with higher mitochondrial dysfunction and increased mitochondrial mass. This effect seems to be specific, as inhibition of CatB and CatL with E-64d had no effect, nor were these proteases significantly released to the cytosol during acetate-induced apoptosis. Using yeast cells, we further show that the role of Pep4p in mitochondrial degradation depends on its protease activity and is complemented by CatD, indicating that this mechanism is conserved. In summary, the clues provided by the yeast model unveiled a novel CatD function in the degradation of damaged mitochondria when autophagy is impaired, which protects CRC cells from acetate-induced apoptosis. Cat

  7. Digesting the Expanding Mechanisms of Autophagy.

    PubMed

    Ktistakis, Nicholas T; Tooze, Sharon A

    2016-08-01

    Autophagy is a catabolic 'self-eating' pathway that is emerging as a crucial integration point in cell physiology. With its own set of genes, the autophagy pathway communicates with virtually all signalling networks and organelles. Recent advances have been made in understanding the origin of the autophagosomal membrane, novel regulators, and the mechanisms by which specific intracellular membranes become autophagy substrates. New studies on noncanonical autophagy, mediated by subsets of autophagy proteins, and the role of autophagy proteins in non-autophagy pathways are also emerging in many different biological contexts. Our understanding of canonical autophagy, including membrane origin and autophagy proteins, needs to be considered together with emerging noncanonical pathways. PMID:27050762

  8. Anti-oxidative cellular protection effect of fasting-induced autophagy as a mechanism for hormesis.

    PubMed

    Moore, Michael N; Shaw, Jennifer P; Ferrar Adams, Dawn R; Viarengo, Aldo

    2015-06-01

    The aim of this investigation was to test the hypothesis that fasting-induced augmented lysosomal autophagic turnover of cellular proteins and organelles will reduce potentially harmful lipofuscin (age-pigment) formation in cells by more effectively removing oxidatively damaged proteins. An animal model (marine snail--common periwinkle, Littorina littorea) was used to experimentally test this hypothesis. Snails were deprived of algal food for 7 days to induce an augmented autophagic response in their hepatopancreatic digestive cells (hepatocyte analogues). This treatment resulted in a 25% reduction in the cellular content of lipofuscin in the digestive cells of the fasting animals in comparison with snails fed ad libitum on green alga (Ulva lactuca). Similar findings have previously been observed in the digestive cells of marine mussels subjected to copper-induced oxidative stress. Additional measurements showed that fasting significantly increased cellular health based on lysosomal membrane stability, and reduced lipid peroxidation and lysosomal/cellular triglyceride. These findings support the hypothesis that fasting-induced augmented autophagic turnover of cellular proteins has an anti-oxidative cytoprotective effect by more effectively removing damaged proteins, resulting in a reduction in the formation of potentially harmful proteinaceous aggregates such as lipofuscin. The inference from this study is that autophagy is important in mediating hormesis. An increase was demonstrated in physiological complexity with fasting, using graph theory in a directed cell physiology network (digraph) model to integrate the various biomarkers. This was commensurate with increased health status, and supportive of the hormesis hypothesis. The potential role of enhanced autophagic lysosomal removal of damaged proteins in the evolutionary acquisition of stress tolerance in intertidal molluscs is discussed and parallels are drawn with the growing evidence for the involvement of

  9. In vivo effect of an antilipolytic drug (3,5'-dimethylpyrazole) on autophagic proteolysis and autophagy-related gene expression in rat liver

    SciTech Connect

    Donati, Alessio; Ventruti, Annamaria; Cavallini, Gabriella; Masini, Matilde; Vittorini, Simona; Chantret, Isabelle; Codogno, Patrice; Bergamini, Ettore

    2008-02-15

    Autophagy is an intracellular pathway induced by starvation, inhibited by nutrients, that is responsible for degradation of long-lived proteins and altered cell organelles. This process is involved in cell maintenance could be induced by antilipolytic drugs and may have anti-aging effects [A. Donati, The involvement of macroautophagy in aging and anti-aging interventions, Mol. Aspects Med. 27 (2006) 455-470]. We analyzed the effect of an intraperitoneal injection of an antilipolytic agent (3,5'-dimethylpyrazole, DMP, 12 mg/kg b.w.), that mimics nutrient shortage on autophagy and expression of autophagic genes in the liver of male 3-month-old Sprague-Dawley albino rats. Autophagy was evaluated by observing electron micrographs of the liver autophagosomal compartment and by monitoring protein degradation assessed by the release of valine into the bloodstream. LC3 gene expression, whose product is one of the best known markers of autophagy, was also monitored. As expected, DMP decreased the plasma levels of free fatty acids, glucose, and insulin and increased autophagic vacuoles and proteolysis. DMP treatment caused an increase in the expression of the LC3 gene although this occurred later than the induction of authophagic proteolysis caused by DMP. Glucose treatment rescued the effects caused by DMP on glucose and insulin plasma levels and negatively affected the rate of autophagic proteolysis, but did not suppress the positive regulatory effect on LC3 mRNA levels. In conclusion, antilipolytic drugs may induce both autophagic proteolysis and higher expression of an autophagy-related gene and the effect on autophagy gene expression might not be secondary to the stimulation of autophagic proteolysis.

  10. Autophagy and pancreas disease.

    PubMed

    Vaccaro, María I

    2008-01-01

    Autophagy is an evolutionarily preserved degradation process of cytoplasmic cellular constituents, which has been known for its role in protecting cells against stresses such as starvation and in eliminating defective subcellular structures. It is essentially a form of self-cannibalism - hence the name that means 'self-eating' - in which the cell breaks down its own components. By mostly morphological studies, autophagy has been linked to a variety of pathological processes such as neurodegenerative diseases and tumorigenesis, which highlights its biological and medical importance. However, whether autophagy protects from or causes disease is unclear. Autophagic morphology was described in human pancreatitis by Helin et al. in 1980. Actually, acute pancreatitis is one of the earlier pathological processes where autophagy has been described in a human tissue. Autophagy, autodigestion and cell death are early cellular events in acute pancreatitis. The aim of this review is to introduce a description of the autophagic process and to discuss the possible role of autophagy in acute pancreatitis. PMID:18714176

  11. Optineurin: The autophagy connection.

    PubMed

    Ying, Hongyu; Yue, Beatrice Y J T

    2016-03-01

    Optineurin is a cytosolic protein encoded by the OPTN gene. Mutations of OPTN are associated with normal tension glaucoma and amyotrophic lateral sclerosis. Autophagy is an intracellular degradation system that delivers cytoplasmic components to the lysosomes. It plays a wide variety of physiological and pathophysiological roles. The optineurin protein is a selective autophagy receptor (or adaptor), containing an ubiquitin binding domain with the ability to bind polyubiquitinated cargoes and bring them to autophagosomes via its microtubule-associated protein 1 light chain 3-interacting domain. It is involved in xenophagy, mitophagy, aggrephagy, and tumor suppression. Optineurin can also mediate the removal of protein aggregates through an ubiquitin-independent mechanism. This protein in addition can induce autophagy upon overexpression or mutation. When overexpressed or mutated, the optineurin protein also serves as a substrate for autophagic degradation. In the present review, the multiple connections of optineurin to autophagy are highlighted. PMID:26142952

  12. Autophagy During Cardiac Stress: Joys and Frustrations of Autophagy

    PubMed Central

    Gottlieb, Roberta A.; Mentzer, Robert M.

    2013-01-01

    The study of autophagy has been transformed by the cloning of most genes in the pathway and the introduction of GFP-LC3 as a reporter to allow visual assessment of autophagy. The field of cardiac biology is not alone in attempting to understand the implications of autophagy. The purpose of this review is to address some of the controversies and conundrums associated with the evolving studies of autophagy in the heart. Autophagy is a cellular process involving a complex orchestration of regulatory gene products as well as machinery for assembly, selective targeting, and degradation of autophagosomes and their contents. Our understanding of the role of autophagy in human disease is rapidly evolving as investigators examine the process in different tissues and different pathophysiological contexts. In the field of heart disease, autophagy has been examined in the settings of ischemia and reperfusion, preconditioning, cardiac hypertrophy, and heart failure. This review addresses the role of autophagy in cardioprotection, the balance of catabolism and anabolism, the concept of mitochondrial quality control, and the implications of impaired autophagic flux or frustrated autophagy. PMID:20148666

  13. The Essential Autophagy Gene ATG7 Modulates Organ Fibrosis via Regulation of Endothelial-to-Mesenchymal Transition*

    PubMed Central

    Singh, Krishna K.; Lovren, Fina; Pan, Yi; Quan, Adrian; Ramadan, Azza; Matkar, Pratiek N.; Ehsan, Mehroz; Sandhu, Paul; Mantella, Laura E.; Gupta, Nandini; Teoh, Hwee; Parotto, Matteo; Tabuchi, Arata; Kuebler, Wolfgang M.; Al-Omran, Mohammed; Finkel, Toren; Verma, Subodh

    2015-01-01

    Pulmonary fibrosis is a progressive disease characterized by fibroblast proliferation and excess deposition of collagen and other extracellular matrix components. Although the origin of fibroblasts is multifactorial, recent data implicate endothelial-to-mesenchymal transition as an important source of fibroblasts. We report herein that loss of the essential autophagy gene ATG7 in endothelial cells (ECs) leads to impaired autophagic flux accompanied by marked changes in EC architecture, loss of endothelial, and gain of mesenchymal markers consistent with endothelial-to-mesenchymal transition. Loss of ATG7 also up-regulates TGFβ signaling and key pro-fibrotic genes in vitro. In vivo, EC-specific ATG7 knock-out mice exhibit a basal reduction in endothelial-specific markers and demonstrate an increased susceptibility to bleomycin-induced pulmonary fibrosis and collagen accumulation. Our findings help define the role of endothelial autophagy as a potential therapeutic target to limit organ fibrosis, a condition for which presently there are no effective available treatments. PMID:25527499

  14. Autophagy in plants and phytopathogens.

    PubMed

    Yoshimoto, Kohki; Takano, Yoshitaka; Sakai, Yasuyoshi

    2010-04-01

    Plants and plant-associated microorganisms including phytopathogens have to adapt to drastic changes in environmental conditions. Because of their immobility, plants must cope with various types of environmental stresses such as starvation, oxidative stress, drought stress, and invasion by phytopathogens during their differentiation, development, and aging processes. Here we briefly describe the early studies of plant autophagy, summarize recent studies on the molecular functions of ATG genes, and speculate on the role of autophagy in plants and phytopathogens. Autophagy regulates senescence and pathogen-induced cell death in plants, and autophagy and pexophagy play critical roles in differentiation and the invasion of host cells by phytopathogenic fungi. PMID:20079356

  15. 8-p-Hdroxybenzoyl Tovarol Induces Paraptosis Like Cell Death and Protective Autophagy in Human Cervical Cancer HeLa Cells.

    PubMed

    Zhang, Cui; Jiang, Yingnan; Zhang, Jin; Huang, Jian; Wang, Jinhui

    2015-01-01

    8-p-Hdroxybenzoyl tovarol (TAW) is a germacrane-type sesquiterpenoid that can be isolated from the roots of Ferula dissecta (Ledeb.) Ledeb. In this study, the growth inhibitory effects induced by TAW were screened on some types of tumor cells, and the mechanism was investigated on TAW-induced growth inhibition, including paraptosis and autophagy in human cervical cancer HeLa cells. TAW-induced paraptosis involved extensive cytoplasmic vacuolization in the absence of caspase activation. Additionally, TAW evoked cell paraptotic death mediated by endoplasmic reticulum (ER) stress and unfolded protein response (UPR). Autophagy induced by TAW was found to antagonize paraptosis in HeLa cells. This effect was enhanced by rapamycin and suppressed by the autophagy inhibitor, 3-methyladenine (3MA). Loss of beclin 1 (an autophagic regulator) function led to promote ER stress. Taken together, these results suggest that TAW induces paraptosis like cell death and protective autophagy in HeLa cells, which would provide a new clue for exploiting TAW as a promising agent for the treatment of cervical cancer. PMID:26147427

  16. 8-p-Hdroxybenzoyl Tovarol Induces Paraptosis Like Cell Death and Protective Autophagy in Human Cervical Cancer HeLa Cells

    PubMed Central

    Zhang, Cui; Jiang, Yingnan; Zhang, Jin; Huang, Jian; Wang, Jinhui

    2015-01-01

    8-p-Hdroxybenzoyl tovarol (TAW) is a germacrane-type sesquiterpenoid that can be isolated from the roots of Ferula dissecta (Ledeb.) Ledeb. In this study, the growth inhibitory effects induced by TAW were screened on some types of tumor cells, and the mechanism was investigated on TAW-induced growth inhibition, including paraptosis and autophagy in human cervical cancer HeLa cells. TAW-induced paraptosis involved extensive cytoplasmic vacuolization in the absence of caspase activation. Additionally, TAW evoked cell paraptotic death mediated by endoplasmic reticulum (ER) stress and unfolded protein response (UPR). Autophagy induced by TAW was found to antagonize paraptosis in HeLa cells. This effect was enhanced by rapamycin and suppressed by the autophagy inhibitor, 3-methyladenine (3MA). Loss of beclin 1 (an autophagic regulator) function led to promote ER stress. Taken together, these results suggest that TAW induces paraptosis like cell death and protective autophagy in HeLa cells, which would provide a new clue for exploiting TAW as a promising agent for the treatment of cervical cancer. PMID:26147427

  17. Insulin Protects Hepatic Lipotoxicity by Regulating ER Stress through the PI3K/Akt/p53 Involved Pathway Independently of Autophagy Inhibition

    PubMed Central

    Ning, Hua; Sun, Zongxiang; Liu, Yunyun; Liu, Lei; Hao, Liuyi; Ye, Yaxin; Feng, Rennan; Li, Jie; Li, Ying; Chu, Xia; Li, Songtao; Sun, Changhao

    2016-01-01

    The detrimental role of hepatic lipotoxicity has been well-implicated in the pathogenesis of NAFLD. Previously, we reported that inhibiting autophagy aggravated saturated fatty acid (SFA)-induced hepatotoxicity. Insulin, a physiological inhibitor of autophagy, is commonly increased within NAFLD mainly caused by insulin resistance. We therefore hypothesized that insulin augments the sensitivity of hepatocyte to SFA-induced lipotoxicity. The present study was conducted via employing human and mouse hepatocytes, which were exposed to SFAs, insulin, or their combination. Unexpectedly, our results indicated that insulin protected hepatocytes against SFA-induced lipotoxicity, based on the LDH, MTT, and nuclear morphological measurements, and the detection from cleaved-Parp-1 and -caspase-3 expressions. We subsequently clarified that insulin led to a rapid and short-period inhibition of autophagy, which was gradually recovered after 1 h incubation in hepatocytes, and such extent of inhibition was insufficient to aggravate SFA-induced lipotoxicity. The mechanistic study revealed that insulin-induced alleviation of ER stress contributed to its hepatoprotective role. Pre-treating hepatocytes with insulin significantly stimulated phosphorylated-Akt and reversed SFA-induced up-regulation of p53. Chemical inhibition of p53 by pifithrin-α robustly prevented palmitate-induced cell death. The PI3K/Akt pathway blockade by its special antagonist abolished the protective role of insulin against SFA-induced lipotoxicity and p53 up-regulation. Furthermore, we observed that insulin promoted intracellular TG deposits in hepatocytes in the present of palmitate. However, blocking TG accumulation via genetically silencing DGAT-2 did not prevent insulin-protected lipotoxicity. Our study demonstrated that insulin strongly protected against SFA-induced lipotoxicity in hepatocytes mechanistically through alleviating ER stress via a PI3K/Akt/p53 involved pathway but independently from autophagy

  18. The autophagy gene Wdr45/Wipi4 regulates learning and memory function and axonal homeostasis

    PubMed Central

    Zhao, Yan G; Sun, Le; Miao, Guangyan; Ji, Cuicui; Zhao, Hongyu; Sun, Huayu; Miao, Lin; Yoshii, Saori R.; Mizushima, Noboru; Wang, Xiaoqun; Zhang, Hong

    2015-01-01

    WDR45/WIPI4, encoding a WD40 repeat-containing PtdIns(3)P binding protein, is essential for the basal autophagy pathway. Mutations in WDR45 cause the neurodegenerative disease β-propeller protein-associated neurodegeneration (BPAN), a subtype of NBIA. We generated CNS-specific Wdr45 knockout mice, which exhibit poor motor coordination, greatly impaired learning and memory, and extensive axon swelling with numerous axon spheroids. Autophagic flux is defective and SQSTM1 (sequestosome-1)/p62 and ubiquitin-positive protein aggregates accumulate in neurons and swollen axons. Nes-Wdr45fl/Y mice recapitulate some hallmarks of BPAN, including cognitive impairment and defective axonal homeostasis, providing a model for revealing the disease pathogenesis of BPAN and also for investigating the possible role of autophagy in axon maintenance. PMID:26000824

  19. Alcohol Dehydrogenase Protects against Endoplasmic Reticulum Stress-Induced Myocardial Contractile Dysfunction via Attenuation of Oxidative Stress and Autophagy: Role of PTEN-Akt-mTOR Signaling

    PubMed Central

    Pang, Jiaojiao; Fuller, Nathan D.; Hu, Nan; Barton, Linzi A.; Henion, Jeremy M.; Guo, Rui; Chen, Yuguo; Ren, Jun

    2016-01-01

    Background The endoplasmic reticulum (ER) plays an essential role in ensuring proper folding of the newly synthesized proteins. Aberrant ER homeostasis triggers ER stress and development of cardiovascular diseases. ADH is involved in catalyzing ethanol to acetaldehyde although its role in cardiovascular diseases other than ethanol metabolism still remains elusive. This study was designed to examine the impact of ADH on ER stress-induced cardiac anomalies and underlying mechanisms involved using cardiac-specific overexpression of alcohol dehydrogenase (ADH). Methods ADH and wild-type FVB mice were subjected to the ER stress inducer tunicamycin (1 mg/kg, i.p., for 48 hrs). Myocardial mechanical and intracellular Ca2+ properties, ER stress, autophagy and associated cell signaling molecules were evaluated. Results ER stress compromised cardiac contractile function (evidenced as reduced fractional shortening, peak shortening, maximal velocity of shortening/relengthening, prolonged relengthening duration and impaired intracellular Ca2+ homeostasis), oxidative stress and upregulated autophagy (increased LC3B, Atg5, Atg7 and p62), along with dephosphorylation of PTEN, Akt and mTOR, all of which were attenuated by ADH. In vitro study revealed that ER stress-induced cardiomyocyte anomaly was abrogated by ADH overexpression or autophagy inhibition using 3-MA. Interestingly, the beneficial effect of ADH was obliterated by autophagy induction, inhibition of Akt and mTOR. ER stress also promoted phosphorylation of the stress signaling ERK and JNK, the effect of which was unaffected by ADH transgene. Conclusions Taken together, these findings suggested that ADH protects against ER stress-induced cardiac anomalies possibly via attenuation of oxidative stress and PTEN/Akt/mTOR pathway-regulated autophagy. PMID:26807981

  20. A small-molecule scaffold induces autophagy in primary neurons and protects against toxicity in a Huntington disease model

    PubMed Central

    Tsvetkov, Andrey S.; Miller, Jason; Arrasate, Montserrat; Wong, Jinny S.; Pleiss, Michael A.; Finkbeiner, Steven

    2010-01-01

    Autophagy is an intracellular turnover pathway. It has special relevance for neurodegenerative proteinopathies, such as Alzheimer disease, Parkinson disease, and Huntington disease (HD), which are characterized by the accumulation of misfolded proteins. Although induction of autophagy enhances clearance of misfolded protein and has therefore been suggested as a therapy for proteinopathies, neurons appear to be less responsive to classic autophagy inducers than nonneuronal cells. Searching for improved inducers of neuronal autophagy, we discovered an N10-substituted phenoxazine that, at proper doses, potently and safely up-regulated autophagy in neurons in an Akt- and mTOR-independent fashion. In a neuron model of HD, this compound was neuroprotective and decreased the accumulation of diffuse and aggregated misfolded protein. A structure/activity analysis with structurally similar compounds approved by the US Food and Drug Administration revealed a defined pharmacophore for inducing neuronal autophagy. This pharmacophore should prove useful in studying autophagy in neurons and in developing therapies for neurodegenerative proteinopathies. PMID:20833817

  1. Investigating regulatory signatures of human autophagy related gene 5 (ATG5) through functional in silico analysis.

    PubMed

    Vij, Avni; Randhawa, Rohit; Parkash, Jyoti; Changotra, Harish

    2016-09-01

    Autophagy is an essential, homeostatic process which removes damaged cellular proteins and organelles for cellular renewal. ATG5, a part of E3 ubiquitin ligase-like complex (Atg12-Atg5/Atg16L1), is a key regulator involved in autophagosome formation - a crucial phase of autophagy. In this study, we used different in silico methods for comprehensive analysis of ATG5 to investigate its less explored regulatory activity. We have predicted various physico-chemical parameters and two possible transmembrane models that helped in exposing its functional regions. Twenty four PTM sites and 44 TFBS were identified which could be targeted to modulate the autophagy pathway. Furthermore, LD analysis identified 3 blocks of genotyped SNPs and 2 deleterious nsSNPs that may have damaging impact on protein function and thus could be employed for carrying genome-wide association studies. In conclusion, the information obtained in this study could be helpful for better understanding of regulatory roles of ATG5 and provides a base for its implication in population-based studies. PMID:27617225

  2. The Parkinson's disease-associated genes ATP13A2 and SYT11 regulate autophagy via a common pathway.

    PubMed

    Bento, Carla F; Ashkenazi, Avraham; Jimenez-Sanchez, Maria; Rubinsztein, David C

    2016-01-01

    Forms of Parkinson's disease (PD) are associated with lysosomal and autophagic dysfunction. ATP13A2, which is mutated in some types of early-onset Parkinsonism, has been suggested as a regulator of the autophagy-lysosome pathway. However, little is known about the ATP13A2 effectors and how they regulate this pathway. Here we show that ATP13A2 depletion negatively regulates another PD-associated gene (SYT11) at both transcriptional and post-translational levels. Decreased SYT11 transcription is controlled by a mechanism dependent on MYCBP2-induced ubiquitination of TSC2, which leads to mTORC1 activation and decreased TFEB-mediated transcription of SYT11, while increased protein turnover is regulated by SYT11 ubiquitination and degradation. Both mechanisms account for a decrease in the levels of SYT11, which, in turn, induces lysosomal dysfunction and impaired degradation of autophagosomes. Thus, we propose that ATP13A2 and SYT11 form a new functional network in the regulation of the autophagy-lysosome pathway, which is likely to contribute to forms of PD-associated neurodegeneration. PMID:27278822

  3. Secretory autophagy.

    PubMed

    Ponpuak, Marisa; Mandell, Michael A; Kimura, Tomonori; Chauhan, Santosh; Cleyrat, Cédric; Deretic, Vojo

    2015-08-01

    Autophagy, once viewed exclusively as a cytoplasmic auto-digestive process, has its less intuitive but biologically distinct non-degradative roles. One manifestation of these functions of the autophagic machinery is the process termed secretory autophagy. Secretory autophagy facilitates unconventional secretion of the cytosolic cargo such as leaderless cytosolic proteins, which unlike proteins endowed with the leader (N-terminal signal) peptides cannot enter the conventional secretory pathway normally operating via the endoplasmic reticulum and the Golgi apparatus. Secretory autophagy may also export more complex cytoplasmic cargo and help excrete particulate substrates. Autophagic machinery and autophagy as a process also affect conventional secretory pathways, including the constitutive and regulated secretion, as well as promote alternative routes for trafficking of integral membrane proteins to the plasma membrane. Thus, autophagy and autophagic factors are intimately intertwined at many levels with secretion and polarized sorting in eukaryotic cells. PMID:25988755

  4. Autophagy in stem cells

    PubMed Central

    Guan, Jun-Lin; Simon, Anna Katharina; Prescott, Mark; Menendez, Javier A.; Liu, Fei; Wang, Fen; Wang, Chenran; Wolvetang, Ernst; Vazquez-Martin, Alejandro; Zhang, Jue

    2013-01-01

    Autophagy is a highly conserved cellular process by which cytoplasmic components are sequestered in autophagosomes and delivered to lysosomes for degradation. As a major intracellular degradation and recycling pathway, autophagy is crucial for maintaining cellular homeostasis as well as remodeling during normal development, and dysfunctions in autophagy have been associated with a variety of pathologies including cancer, inflammatory bowel disease and neurodegenerative disease. Stem cells are unique in their ability to self-renew and differentiate into various cells in the body, which are important in development, tissue renewal and a range of disease processes. Therefore, it is predicted that autophagy would be crucial for the quality control mechanisms and maintenance of cellular homeostasis in various stem cells given their relatively long life in the organisms. In contrast to the extensive body of knowledge available for somatic cells, the role of autophagy in the maintenance and function of stem cells is only beginning to be revealed as a result of recent studies. Here we provide a comprehensive review of the current understanding of the mechanisms and regulation of autophagy in embryonic stem cells, several tissue stem cells (particularly hematopoietic stem cells), as well as a number of cancer stem cells. We discuss how recent studies of different knockout mice models have defined the roles of various autophagy genes and related pathways in the regulation of the maintenance, expansion and differentiation of various stem cells. We also highlight the many unanswered questions that will help to drive further research at the intersection of autophagy and stem cell biology in the near future. PMID:23486312

  5. Autophagy blockade sensitizes the anticancer activity of CA-4 via JNK-Bcl-2 pathway

    SciTech Connect

    Li, Yangling; Luo, Peihua; Wang, Jincheng; Dai, Jiabin; Yang, Xiaochun; Wu, Honghai; Yang, Bo He, Qiaojun

    2014-01-15

    Combretastatin A-4 (CA-4) has already entered clinical trials of solid tumors over ten years. However, the limited anticancer activity and dose-dependent toxicity restrict its clinical application. Here, we offered convincing evidence that CA-4 induced autophagy in various cancer cells, which was demonstrated by acridine orange staining of intracellular acidic vesicles, the degradation of p62, the conversion of LC3-I to LC3-II and GFP-LC3 punctate fluorescence. Interestingly, CA-4-mediated apoptotic cell death was further potentiated by pretreatment with autophagy inhibitors (3-methyladenine and bafilomycin A1) or small interfering RNAs against the autophagic genes (Atg5 and Beclin 1). The enhanced anticancer activity of CA-4 and 3-MA was further confirmed in the SGC-7901 xenograft tumor model. These findings suggested that CA-4-elicited autophagic response played a protective role that impeded the eventual cell death while autophagy inhibition was expected to improve chemotherapeutic efficacy of CA-4. Meanwhile, CA-4 treatment led to phosphorylation/activation of JNK and JNK-dependent phosphorylation of Bcl-2. Importantly, JNK inhibitor or JNK siRNA inhibited autophagy but promoted CA-4-induced apoptosis, indicating a key requirement of JNK-Bcl-2 pathway in the activation of autophagy by CA-4. We also identified that pretreatment of Bcl-2 inhibitor (ABT-737) could significantly enhance anticancer activity of CA-4 due to inhibition of autophagy. Taken together, our data suggested that the JNK-Bcl-2 pathway was considered as the critical regulator of CA-4-induced protective autophagy and a potential drug target for chemotherapeutic combination. - Highlights: • Autophagy inhibition could be a potential for combretastatin A-4 antitumor efficacy. • The JNK-Bcl-2 pathway plays a critical role in CA-4-induced autophagy. • ABT-737 enhances CA-4 anticancer activity due to inhibition of autophagy.

  6. Autophagy Regulates Colistin-Induced Apoptosis in PC-12 Cells

    PubMed Central

    Zhang, Ling; Zhao, Yonghao; Ding, Wenjian; Jiang, Guozheng; Lu, Ziyin; Li, Li; Wang, Jinli

    2015-01-01

    Colistin is a cyclic cationic polypeptide antibiotic with activity against multidrug-resistant Gram-negative bacteria. Our recent study demonstrated that colistin induces apoptosis in primary chick cortex neurons and PC-12 cells. Although apoptosis and autophagy have different impacts on cell fate, there is a complex interaction between them. Autophagy plays an important role as a homeostasis regulator by removing excessive or unnecessary proteins and damaged organelles. The aim of the present study was to investigate the modulation of autophagy and apoptosis regulation in PC-12 cells in response to colistin treatment. PC-12 cells were exposed to colistin (125 to 250 μg/ml), and autophagy was detected by visualization of monodansylcadaverine (MDC)-labeled vacuoles, LC3 (microtubule-associated protein 1 light chain 3) immunofluorescence microscopic examination, and Western blotting. Apoptosis was measured by flow cytometry, Hoechst 33258 staining, and Western blotting. Autophagosomes were observed after treatment with colistin for 12 h, and the levels of LC3-II gene expression were determined; observation and protein levels both indicated that colistin induced a high level of autophagy. Colistin treatment also led to apoptosis in PC-12 cells, and the level of caspase-3 expression increased over the 24-h period. Pretreatment of cells with 3-methyladenine (3-MA) increased colistin toxicity in PC-12 cells remarkably. However, rapamycin treatment significantly increased the expression levels of LC3-II and beclin 1 and decreased the rate of apoptosis of PC-12 cells. Our results demonstrate that colistin induced autophagy and apoptosis in PC-12 cells and that the latter was affected by the regulation of autophagy. It is very likely that autophagy plays a protective role in the reduction of colistin-induced cytotoxicity in neurons. PMID:25645826

  7. Overexpression of KAI1 induces autophagy and increases MiaPaCa-2 cell survival through the phosphorylation of extracellular signal-regulated kinases

    SciTech Connect

    Wu, Chun-Yan; Yan, Jun; Yang, Yue-Feng; Xiao, Feng-Jun; Li, Qing-Fang; Zhang, Qun-Wei; Wang, Li-Sheng; Guo, Xiao-Zhong; Wang, Hua

    2011-01-21

    Research highlights: {yields} We first investigate the effects of KAI1 on autophagy in MiaPaCa-2 cells. {yields} Our findings demonstrate that KAI1 induces autophagy, which in turn inhibits KAI1-induced apoptosis. {yields} This study also supplies a possible novel therapeutic method for the treatment of pancreatic cancer using autophagy inhibitors. -- Abstract: KAI1, a metastasis-suppressor gene belonging to the tetraspanin family, is known to inhibit cancer metastasis without affecting the primary tumorigenicity by inhibiting the epidermal growth factor (EGF) signaling pathway. Recent studies have shown that hypoxic conditions of solid tumors induce high-level autophagy and KAI1 expression. However, the relationship between autophagy and KAI1 remains unclear. By using transmission electron microscopy, confocal microscopy, and Western blotting, we found that KAI1 can induce autophagy in a dose- and time-dependent manner in the human pancreatic cell line MiaPaCa-2. KAI1-induced autophagy was confirmed by the expression of autophagy-related proteins LC3 and Beclin 1. KAI1 induces autophagy through phosphorylation of extracellular signal-related kinases rather than that of AKT. KAI1-induced autophagy protects MiaPaCa-2 cells from apoptosis and proliferation inhibition partially through the downregulation of poly [adenosine diphosphate (ADP)-ribose] polymerase (PARP) cleavage and caspase-3 activation.

  8. Comparative gene identification-58 (CGI-58) promotes autophagy as a putative lysophosphatidylglycerol acyltransferase.

    PubMed

    Zhang, Jun; Xu, Dan; Nie, Jia; Han, Ruili; Zhai, Yonggong; Shi, Yuguang

    2014-11-21

    CGI-58 is a lipid droplet-associated protein that, when mutated, causes Chanarin-Dorfman syndrome in humans, which is characterized by excessive storage of triglyceride in various tissues. However, the molecular mechanisms underlying the defect remain elusive. CGI-58 was previously reported to catalyze the resynthesis of phosphatidic acid as a lysophosphatidic acid acyltransferase. In addition to triglyceride, phosphatidic acid is also used a substrate for the synthesis of various mitochondrial phospholipids. In this report, we investigated the propensity of CGI-58 in the remodeling of various phospholipids. We found that the recombinant CGI-58 overexpressed in mammalian cells or purified from Sf9 insect cells catalyzed efficiently the reacylation of lysophosphatidylglycerol to phosphatidylglycerol (PG), which requires acyl-CoA as the acyl donor. In contrast, the recombinant CGI-58 was devoid of acyltransferase activity toward other lysophospholipids. Accordingly, overexpression and knockdown of CGI-58 adversely affected the endogenous PG level in C2C12 cells. PG is a substrate for the synthesis of cardiolipin, which is required for mitochondrial oxidative phosphorylation and mitophagy. Consequently, overexpression and knockdown of CGI-58 adversely affected autophagy and mitophagy in C2C12 cells. In support for a key role of CGI-58 in mitophagy, overexpression of CGI-58 significantly stimulated mitochondrial fission and translocation of PINK1 to mitochondria, key steps involved in mitophagy. Furthermore, overexpression of CGI-58 promoted mitophagic initiation through activation of 5'-AMP-activated protein kinase and inhibition of mTORC1 mammalian target of rapamycin complex 1 signaling, the positive and negative regulators of autophagy, respectively. Together, these findings identified novel molecular mechanisms by which CGI-58 regulates lipid homeostasis, because defective autophagy is implicated in dyslipidemia and fatty liver diseases. PMID:25315780

  9. A Missense Change in the ATG4D Gene Links Aberrant Autophagy to a Neurodegenerative Vacuolar Storage Disease

    PubMed Central

    Kyöstilä, Kaisa; Syrjä, Pernilla; Jagannathan, Vidhya; Chandrasekar, Gayathri; Jokinen, Tarja S.; Seppälä, Eija H.; Becker, Doreen; Drögemüller, Michaela; Dietschi, Elisabeth; Drögemüller, Cord; Lang, Johann; Steffen, Frank; Rohdin, Cecilia; Jäderlund, Karin H.; Lappalainen, Anu K.; Hahn, Kerstin; Wohlsein, Peter; Baumgärtner, Wolfgang; Henke, Diana; Oevermann, Anna; Kere, Juha; Lohi, Hannes; Leeb, Tosso

    2015-01-01

    Inherited neurodegenerative disorders are debilitating diseases that occur across different species. We have performed clinical, pathological and genetic studies to characterize a novel canine neurodegenerative disease present in the Lagotto Romagnolo dog breed. Affected dogs suffer from progressive cerebellar ataxia, sometimes accompanied by episodic nystagmus and behavioral changes. Histological examination revealed unique pathological changes, including profound neuronal cytoplasmic vacuolization in the nervous system, as well as spheroid formation and cytoplasmic aggregation of vacuoles in secretory epithelial tissues and mesenchymal cells. Genetic analyses uncovered a missense change, c.1288G>A; p.A430T, in the autophagy-related ATG4D gene on canine chromosome 20 with a highly significant disease association (p = 3.8 x 10-136) in a cohort of more than 2300 Lagotto Romagnolo dogs. ATG4D encodes a poorly characterized cysteine protease belonging to the macroautophagy pathway. Accordingly, our histological analyses indicated altered autophagic flux in affected tissues. The knockdown of the zebrafish homologue atg4da resulted in a widespread developmental disturbance and neurodegeneration in the central nervous system. Our study describes a previously unknown canine neurological disease with particular pathological features and implicates the ATG4D protein as an important autophagy mediator in neuronal homeostasis. The canine phenotype serves as a model to delineate the disease-causing pathological mechanism(s) and ATG4D function, and can also be used to explore treatment options. Furthermore, our results reveal a novel candidate gene for human neurodegeneration and enable the development of a genetic test for veterinary diagnostic and breeding purposes. PMID:25875846

  10. A missense change in the ATG4D gene links aberrant autophagy to a neurodegenerative vacuolar storage disease.

    PubMed

    Kyöstilä, Kaisa; Syrjä, Pernilla; Jagannathan, Vidhya; Chandrasekar, Gayathri; Jokinen, Tarja S; Seppälä, Eija H; Becker, Doreen; Drögemüller, Michaela; Dietschi, Elisabeth; Drögemüller, Cord; Lang, Johann; Steffen, Frank; Rohdin, Cecilia; Jäderlund, Karin H; Lappalainen, Anu K; Hahn, Kerstin; Wohlsein, Peter; Baumgärtner, Wolfgang; Henke, Diana; Oevermann, Anna; Kere, Juha; Lohi, Hannes; Leeb, Tosso

    2015-04-01

    Inherited neurodegenerative disorders are debilitating diseases that occur across different species. We have performed clinical, pathological and genetic studies to characterize a novel canine neurodegenerative disease present in the Lagotto Romagnolo dog breed. Affected dogs suffer from progressive cerebellar ataxia, sometimes accompanied by episodic nystagmus and behavioral changes. Histological examination revealed unique pathological changes, including profound neuronal cytoplasmic vacuolization in the nervous system, as well as spheroid formation and cytoplasmic aggregation of vacuoles in secretory epithelial tissues and mesenchymal cells. Genetic analyses uncovered a missense change, c.1288G>A; p.A430T, in the autophagy-related ATG4D gene on canine chromosome 20 with a highly significant disease association (p = 3.8 x 10-136) in a cohort of more than 2300 Lagotto Romagnolo dogs. ATG4D encodes a poorly characterized cysteine protease belonging to the macroautophagy pathway. Accordingly, our histological analyses indicated altered autophagic flux in affected tissues. The knockdown of the zebrafish homologue atg4da resulted in a widespread developmental disturbance and neurodegeneration in the central nervous system. Our study describes a previously unknown canine neurological disease with particular pathological features and implicates the ATG4D protein as an important autophagy mediator in neuronal homeostasis. The canine phenotype serves as a model to delineate the disease-causing pathological mechanism(s) and ATG4D function, and can also be used to explore treatment options. Furthermore, our results reveal a novel candidate gene for human neurodegeneration and enable the development of a genetic test for veterinary diagnostic and breeding purposes. PMID:25875846

  11. Gene transfer of master autophagy regulator TFEB results in clearance of toxic protein and correction of hepatic disease in alpha-1-anti-trypsin deficiency

    PubMed Central

    Pastore, Nunzia; Blomenkamp, Keith; Annunziata, Fabio; Piccolo, Pasquale; Mithbaokar, Pratibha; Maria Sepe, Rosa; Vetrini, Francesco; Palmer, Donna; Ng, Philip; Polishchuk, Elena; Iacobacci, Simona; Polishchuk, Roman; Teckman, Jeffrey; Ballabio, Andrea; Brunetti-Pierri, Nicola

    2013-01-01

    Alpha-1-anti-trypsin deficiency is the most common genetic cause of liver disease in children and liver transplantation is currently the only available treatment. Enhancement of liver autophagy increases degradation of mutant, hepatotoxic alpha-1-anti-trypsin (ATZ). We investigated the therapeutic potential of liver-directed gene transfer of transcription factor EB (TFEB), a master gene that regulates lysosomal function and autophagy, in PiZ transgenic mice, recapitulating the human hepatic disease. Hepatocyte TFEB gene transfer resulted in dramatic reduction of hepatic ATZ, liver apoptosis and fibrosis, which are key features of alpha-1-anti-trypsin deficiency. Correction of the liver phenotype resulted from increased ATZ polymer degradation mediated by enhancement of autophagy flux and reduced ATZ monomer by decreased hepatic NFκB activation and IL-6 that drives ATZ gene expression. In conclusion, TFEB gene transfer is a novel strategy for treatment of liver disease of alpha-1-anti-trypsin deficiency. This study may pave the way towards applications of TFEB gene transfer for treatment of a wide spectrum of human disorders due to intracellular accumulation of toxic proteins. PMID:23381957

  12. Autophagy in sepsis: Degradation into exhaustion?

    PubMed

    Ho, Jeffery; Yu, Jun; Wong, Sunny H; Zhang, Lin; Liu, Xiaodong; Wong, Wai T; Leung, Czarina C H; Choi, Gordon; Wang, Maggie H T; Gin, Tony; Chan, Matthew T V; Wu, William K K

    2016-07-01

    Autophagy is one of the innate immune defense mechanisms against microbial challenges. Previous in vitro and in vivo models of sepsis demonstrated that autophagy was activated initially in sepsis, followed by a subsequent phase of impairment. Autophagy modulation appears to be protective against multiple organ injuries in these murine sepsis models. This is achieved in part by preventing apoptosis, maintaining a balance between the productions of pro- and anti-inflammatory cytokines, and preserving mitochondrial functions. This article aims to discuss the role of autophagy in sepsis and the therapeutic potential of autophagy enhancers. PMID:27172163

  13. Histone deacetylase 10 promotes autophagy-mediated cell survival

    PubMed Central

    Oehme, Ina; Linke, Jan-Peter; Böck, Barbara C.; Milde, Till; Lodrini, Marco; Hartenstein, Bettina; Wiegand, Inga; Eckert, Christian; Roth, Wilfried; Kool, Marcel; Kaden, Sylvia; Gröne, Hermann-Josef; Schulte, Johannes H.; Lindner, Sven; Hamacher-Brady, Anne; Brady, Nathan R.; Deubzer, Hedwig E.; Witt, Olaf

    2013-01-01

    Tumor cells activate autophagy in response to chemotherapy-induced DNA damage as a survival program to cope with metabolic stress. Here, we provide in vitro and in vivo evidence that histone deacetylase (HDAC)10 promotes autophagy-mediated survival in neuroblastoma cells. We show that both knockdown and inhibition of HDAC10 effectively disrupted autophagy associated with sensitization to cytotoxic drug treatment in a panel of highly malignant V-MYC myelocytomatosis viral-related oncogene, neuroblastoma derived-amplified neuroblastoma cell lines, in contrast to nontransformed cells. HDAC10 depletion in neuroblastoma cells interrupted autophagic flux and induced accumulation of autophagosomes, lysosomes, and a prominent substrate of the autophagic degradation pathway, p62/sequestosome 1. Enforced HDAC10 expression protected neuroblastoma cells against doxorubicin treatment through interaction with heat shock protein 70 family proteins, causing their deacetylation. Conversely, heat shock protein 70/heat shock cognate 70 was acetylated in HDAC10-depleted cells. HDAC10 expression levels in high-risk neuroblastomas correlated with autophagy in gene-set analysis and predicted treatment success in patients with advanced stage 4 neuroblastomas. Our results demonstrate that HDAC10 protects cancer cells from cytotoxic agents by mediating autophagy and identify this HDAC isozyme as a druggable regulator of advanced-stage tumor cell survival. Moreover, these results propose a promising way to considerably improve treatment response in the neuroblastoma patient subgroup with the poorest outcome. PMID:23801752

  14. Histone deacetylase 10 promotes autophagy-mediated cell survival.

    PubMed

    Oehme, Ina; Linke, Jan-Peter; Böck, Barbara C; Milde, Till; Lodrini, Marco; Hartenstein, Bettina; Wiegand, Inga; Eckert, Christian; Roth, Wilfried; Kool, Marcel; Kaden, Sylvia; Gröne, Hermann-Josef; Schulte, Johannes H; Lindner, Sven; Hamacher-Brady, Anne; Brady, Nathan R; Deubzer, Hedwig E; Witt, Olaf

    2013-07-01

    Tumor cells activate autophagy in response to chemotherapy-induced DNA damage as a survival program to cope with metabolic stress. Here, we provide in vitro and in vivo evidence that histone deacetylase (HDAC)10 promotes autophagy-mediated survival in neuroblastoma cells. We show that both knockdown and inhibition of HDAC10 effectively disrupted autophagy associated with sensitization to cytotoxic drug treatment in a panel of highly malignant V-MYC myelocytomatosis viral-related oncogene, neuroblastoma derived-amplified neuroblastoma cell lines, in contrast to nontransformed cells. HDAC10 depletion in neuroblastoma cells interrupted autophagic flux and induced accumulation of autophagosomes, lysosomes, and a prominent substrate of the autophagic degradation pathway, p62/sequestosome 1. Enforced HDAC10 expression protected neuroblastoma cells against doxorubicin treatment through interaction with heat shock protein 70 family proteins, causing their deacetylation. Conversely, heat shock protein 70/heat shock cognate 70 was acetylated in HDAC10-depleted cells. HDAC10 expression levels in high-risk neuroblastomas correlated with autophagy in gene-set analysis and predicted treatment success in patients with advanced stage 4 neuroblastomas. Our results demonstrate that HDAC10 protects cancer cells from cytotoxic agents by mediating autophagy and identify this HDAC isozyme as a druggable regulator of advanced-stage tumor cell survival. Moreover, these results propose a promising way to considerably improve treatment response in the neuroblastoma patient subgroup with the poorest outcome. PMID:23801752

  15. Differentially expressed microRNA identification and target gene function analysis in starvation-induced autophagy of AR42J pancreatic acinar cells.

    PubMed

    Gao, Bo; Wang, Duanping; Sun, Wang; Meng, Xianzhi; Zhang, Weihui; Xue, Dongbo

    2016-07-01

    Acute pancreatitis (AP) is a common acute digestive tract disease, with increased morbidity and mortality, and an unclear pathogenesis. Trypsinogen activation in pancreatic acinar cells may be the primary mechanism underlying the development of AP. Previous studies reported that autophagy participates in the formation of acinar cell vacuoles in AP and in the process of trypsinogen activation as an important cause of AP. Furthermore, microRNAs (miRNAs) maintain the autophagy process by regulating the expression of autophagy‑associated genes. In the present study, an in vitro pancreatic acinar cell autophagy model was established using the AR42J starvation‑induced pancreatic acinar cell line. Twenty differentially expressed microRNAs were identified using miRNA microarray. Bioinformatics analysis was used to predict the target genes of miRNAs and analyze the functions of differentially expressed miRNAs. The results demonstrated that only the downregulated miRNA rno‑miR‑148b‑3p predicted 593 target genes with a statistical significance (P<0.05), from which 10 genes were autophagy‑associated. The results of gene ontology and pathway analyses demonstrated that the target genes of miRNAs were enriched in the Response to insulin stimulus, Regulation of cell death and the Insulin signaling pathways (P<0.05, FDR<0.05). In addition, protein‑protein interaction network analysis demonstrated a widespread interaction among the 593 target genes. The results of the present study may provide novel targets for research on the mechanisms of autophagy-promoted AP and AP treatment. PMID:27175615

  16. Autophagy and gap junctional intercellular communication inhibition are involved in cadmium-induced apoptosis in rat liver cells

    SciTech Connect

    Zou, Hui; Zhuo, Liling; Han, Tao; Hu, Di; Yang, Xiaokang; Wang, Yi; Yuan, Yan; Gu, Jianhong; Bian, Jianchun; Liu, Xuezhong; Liu, Zongping

    2015-04-17

    Cadmium (Cd) is known to induce hepatotoxicity, yet the underlying mechanism of how this occurs is not fully understood. In this study, Cd-induced apoptosis was demonstrated in rat liver cells (BRL 3A) with apoptotic nuclear morphological changes and a decrease in cell index (CI) in a time- and concentration-dependent manner. The role of gap junctional intercellular communication (GJIC) and autophagy in Cd-induced apoptosis was investigated. Cd significantly induced GJIC inhibition as well as downregulation of connexin 43 (Cx43). The prototypical gap junction blocker carbenoxolone disodium (CBX) exacerbated the Cd-induced decrease in CI. Cd treatment was also found to cause autophagy, with an increase in mRNA expression of autophagy-related genes Atg-5, Atg-7, Beclin-1, and microtubule-associated protein light chain 3 (LC3) conversion from cytosolic LC3-I to membrane-bound LC3-II. The autophagic inducer rapamycin (RAP) prevented the Cd-induced CI decrease, while the autophagic inhibitor chloroquine (CQ) caused a further reduction in CI. In addition, CBX promoted Cd-induced autophagy, as well as changes in expression of Atg-5, Atg-7, Beclin-1 and LC3. CQ was found to block the Cd-induced decrease in Cx43 and GJIC inhibition, whereas RAP had opposite effect. These results demonstrate that autophagy plays a protective role during Cd-induced apoptosis in BRL 3A cells during 6 h of experiment, while autophagy exacerbates Cd-induced GJIC inhibition which has a negative effect on cellular fate. - Highlights: • GJIC and autophagy is crucial for biological processes. • Cd exposure causes GJIC inhibition and autophagy increase in BRL 3A cells. • Autophagy protects Cd induced BRL 3A cells apoptosis at an early stage. • Autophagy exacerbates Cd-induced GJIC inhibition. • GJIC plays an important role in autophagy induced cell death or survival.

  17. The Role of Autophagy in Mammalian Development

    PubMed Central

    Cecconi, Francesco; Levine, Beth

    2009-01-01

    Autophagy is important for the degradation of bulk cytoplasm, long-lived proteins, and entire organelles. In lower eukaryotes, autophagy functions as a cell death mechanism or as a stress response during development. However, autophagy’s significance in vertebrate development, and the role (if any) of vertebrate-specific factors in its regulation, remains unexplained. Through careful analysis of the current autophagy gene mutant mouse models, we propose that in mammals, autophagy may be involved in specific cytosolic rearrangements needed for proliferation, death, and differentiation during embryogenesis and postnatal development. Thus, autophagy is a process of cytosolic “renovation,” crucial in cell fate decisions. PMID:18804433

  18. Mir-30d increases intracellular survival of Helicobacter pylori through inhibition of autophagy pathway

    PubMed Central

    Yang, Xiao-Jun; Si, Ruo-Huang; Liang, Yu-He; Ma, Bing-Qiang; Jiang, Ze-Bin; Wang, Bin; Gao, Peng

    2016-01-01

    AIM: To determine if mir-30d inhibits the autophagy response to Helicobacter pylori (H. pylori) invasion and increases H. pylori intracellular survival. METHODS: The expression of mir-30d was detected by quantitative polymerase chain reaction (PCR), and autophagy level was examined by transmission electron microscopy, western blot, and GFP-LC3 puncta assay in human AGS cells and GES-1 cells. Luciferase reporter assay was applied to confirm the specificity of mir-30d regulation on the expression of several core molecules involved in autophagy pathway. The expression of multiple core proteins were analyzed at both the mRNA and protein level, and the intracellular survival of H. pylori after different treatments was detected by gentamicin protection assay. RESULTS: Autophagy level was increased in AGS and GES-1 cells in response to H. pylori infection, which was accompanied by upregulation of mir-30d expression (P < 0.05, vs no H. pylori infection). In the two gastric epithelial cell lines, mimic mir-30d was found to repress the autophagy process, whereas mir-30d inhibitor increased autophagy response to H. pylori invasion. mir-30d mimic decreased the luciferase activity of wild type reporter plasmids carrying the 3′ untranslated region (UTR) of all five tested genes (ATG2B, ATG5, ATG12, BECN1, and BNIP3L), whereas it had no effect on the mutant reporter plasmids. These five genes are core genes of autophagy pathway, and their expression was reduced significantly after mir-30d mimic transfection (P < 0.05, vs control cells without mir-30d mimic treatment). Mir-30d mimic transfection and direct inhibition of autophagy increased the intracellular survival of H. pylori in AGS cells. CONCLUSION: Mir-30d increases intracellular survival of H. pylori in gastric epithelial cells through inhibition of multiple core proteins in the autophagy pathway. PMID:27099441

  19. Heme oxygenase‑1 protects H2O2‑insulted glomerular mesangial cells from excessive autophagy.

    PubMed

    Xu, Jia; Li, Jinshun; Wang, Jinhua; Chi, Yanchun; Zhang, Kun; Cui, Rui

    2016-06-01

    Increasing evidence has demonstrated that the activation of heme oxygenase (HO)‑1 reduces autophagy stimulated by oxidative stress injury, in which the supraphysiological production of reactive oxygen species (ROS) is detected. However, the potential mechanism underlying this effect remains unclear. The present study aimed to investigate the function of HO‑1 activation in the regulation of autophagy in glomerular mesangial cells subjected to H2O2‑induced oxidative stress injury. The results demonstrated that the HO‑1 agonist, hemin, reduces the LC3 protein level, which was enhanced by H2O2 treatment. Furthermore, hemin‑activated HO‑1 may function as a regulator of oxidative stress‑induced autophagy in a dose‑dependent manner. Pharmacological activation of c‑Jun N‑terminal kinase (JNK) inhibited the effect of hemin, indicating that the JNK signaling pathway is associated with the mechanism of HO‑1 in impeding excessive autophagy. In addition to successfully alleviating H2O2‑induced oxidative stress and cellular apoptosis, hemin‑activated HO‑1 may provide cytoprotection against rapamycin, a specific autophagy agonist. The present result suggested the inhibitory action of HO‑1 in the avoidance of a potentially enhanced linkage between autophagy and apoptosis, particularly in the setting of excessive ROS. Therefore, enhancing the intracellular activity of HO‑1 may assist the crosstalk between oxidative stress, autophagy and apoptosis, and represent a novel therapeutic strategy for renal ischemic disease. PMID:27122182

  20. Chromatin features, RNA polymerase II and the comparative expression of lens genes encoding crystallins, transcription factors, and autophagy mediators

    PubMed Central

    Sun, Jian; Rockowitz, Shira; Chauss, Daniel; Wang, Ping; Kantorow, Marc; Zheng, Deyou

    2015-01-01

    Purpose Gene expression correlates with local chromatin structure. Our studies have mapped histone post-translational modifications, RNA polymerase II (pol II), and transcription factor Pax6 in lens chromatin. These data represent the first genome-wide insights into the relationship between lens chromatin structure and lens transcriptomes and serve as an excellent source for additional data analysis and refinement. The principal lens proteins, the crystallins, are encoded by predominantly expressed mRNAs; however, the regulatory mechanisms underlying their high expression in the lens remain poorly understood. Methods The formaldehyde-assisted identification of regulatory regions (FAIRE-Seq) was employed to analyze newborn lens chromatin. ChIP-seq and RNA-seq data published earlier (GSE66961) have been used to assist in FAIRE-seq data interpretation. RNA transcriptomes from murine lens epithelium, lens fibers, erythrocytes, forebrain, liver, neurons, and pancreas were compared to establish the gene expression levels of the most abundant mRNAs versus median gene expression across other differentiated cells. Results Normalized RNA expression data from multiple tissues show that crystallins rank among the most highly expressed genes in mammalian cells. These findings correlate with the extremely high abundance of pol II all across the crystallin loci, including crystallin genes clustered on chromosomes 1 and 5, as well as within regions of “open” chromatin, as identified by FAIRE-seq. The expression levels of mRNAs encoding DNA-binding transcription factors (e.g., Foxe3, Hsf4, Maf, Pax6, Prox1, Sox1, and Tfap2a) revealed that their transcripts form “clusters” of abundant mRNAs in either lens fibers or lens epithelium. The expression of three autophagy regulatory mRNAs, encoding Tfeb, FoxO1, and Hif1α, was found within a group of lens preferentially expressed transcription factors compared to the E12.5 forebrain. Conclusions This study reveals novel features of

  1. α-lipoic acid protects against hypoxia/reoxygenation-induced injury in human umbilical vein endothelial cells through suppression of apoptosis and autophagy

    PubMed Central

    ZHANG, JINGJING; DENG, HOULIANG; LIU, LI; LIU, XIAOXIA; ZUO, XIALIN; XU, QIAN; WU, ZHUOMIN; PENG, XIAOBIN; JI, AIMIN

    2015-01-01

    α-lipoic acid (ALA) is known as a powerful antioxidant, which has been reported to have protective effects against various cardiovascular diseases. The present study aimed to determine whether ALA pre- or post-treatment induced protective effects against hypoxia/reoxygenation-induced injury via inhibition of apoptosis and autophagy in human umbilical vein endothelial cells (HUVECs). In order to simulate the conditions of hypoxia/reoxygenation, HUVECs were subjected to 4 h of oxygen-glucose deprivation (OGD) followed by 12 h of reoxygenation. For the pre-treatment, ALA was added to the buffer 12 h prior to OGD, whereas for the post-treatment, ALA was added at the initiation of reoxygenation. The results demonstrated that ALA pre- or post-treatment significantly reduced lactate dehydrogenase (LDH) release induced through hypoxia/reoxygenation in HUVECs in a dose-dependent manner; of note, 1 mM ALA pre- or post-treatment exhibited the most potent protective effects. In addition, ALA significantly reduced hypoxia/reoxygenation-induced loss of mitochondrial membrane potential, apoptosis and the expression of cleaved caspase-3 in HUVECs. In the presence of the specific autophagy inhibitor 3-methyladenine, hypoxia/reoxygenation-induced apoptosis was significantly reduced. Furthermore, the formation of autophagosomes, cytosolic microtubule-associated protein 1A/1B-light chain 3 ratio and beclin1 levels significantly increased following hypoxia/reoxygenation injury; however, all of these effects were ameliorated following pre- or post-treatment with ALA. The results of the present study suggested that ALA may provide beneficial protection against hypoxia/reoxygenation-induced injury via attenuation of apoptosis and autophagy in HUVECs. PMID:25684163

  2. Folate deprivation modulates the expression of autophagy- and circadian-related genes in HT-22 hippocampal neuron cells through GR-mediated pathway.

    PubMed

    Sun, Qinwei; Yang, Yang; Li, Xi; He, Bin; Jia, Yimin; Zhang, Nana; Zhao, Ruqian

    2016-08-01

    Folic acid (FA) is an extremely important nutrient for brain formation and development. FA deficiency is highly linked to brain degeneration and age-related diseases, which are also associated with autophagic activities and circadian rhythm in hippocampal neurons. However, little is known how autophagy- and circadian-related genes in hippocampal neurons are regulated under FA deficiency. Here, hippocampal neuroncells (HT-22) were employed to determine the effect of FA deprivation (FD) on the expression of relevant genes and to reveal the potential role of glucocorticoid receptor (GR). FD increased autophagic activities in HT-22 cells, associated with significantly (P<0.05) enhanced GR activation indicated by higher ratio of GR phosphorylation. Out of 17 autophagy-related genes determined, 8 was significantly (P<0.05) up-regulated in FD group, which includes ATG2b, ATG3, ATG4c, ATG5, ATG10, ATG12, ATG13 and ATG14. Meanwhile, 4 out of 7 circadian-related genes detected, Clock, Cry1, Cry2 and Per2, were significantly (P<0.05) up-regulated. The protein content of autophagy markers, LC3A and LC3B, was also increased significantly (P<0.05). ChIP assay showed that FD promoted (P<0.05) GR binding to the promoter sequence of ATG3 and Per2. Moreover, MeDIP analysis demonstrated significant (P<0.05) hypomethylation in the promoter sequence of ATG12, ATG13 and Per2 genes. Together, we speculate that FD increases the transcription of autophagy- and circadian-related genes through, at least partly, GR-mediated pathway. Our results provide a basis for future investigations into the intracellular regulatory network in response to folate deficiency. PMID:27133904

  3. Suppression of autophagy augments the radiosensitizing effects of STAT3 inhibition on human glioma cells

    SciTech Connect

    Yuan, Xiaopeng; Du, Jie; Hua, Song; Zhang, Haowen; Gu, Cheng; Wang, Jie; Yang, Lei; Huang, Jianfeng; Yu, Jiahua Liu, Fenju

    2015-01-15

    Radiotherapy is an essential component of the standard therapy for newly diagnosed glioblastoma. To increase the radiosensitivity of glioma cells is a feasible solution to improve the therapeutic effects. It has been suggested that inhibition of signal transducer and activator of transcription 3 (STAT3) can radiosensitize glioma cells, probably via the activation of mitochondrial apoptotic pathway. In this study, human malignant glioma cells, U251 and A172, were treated with an STAT3 inhibitor, WP1066, or a short hairpin RNA plasmid targeting STAT3 to suppress the activation of STAT3 signaling. The radiosensitizing effects of STAT3 inhibition were confirmed in glioma cells. Intriguingly, combination of ionizing radiation exposure and STAT3 inhibition triggered a pronounced increase of autophagy flux. To explore the role of autophagy, glioma cells were treated with 3-methyladenine or siRNA for autophagy-related gene 5, and it was demonstrated that inhibition of autophagy further strengthened the radiosensitizing effects of STAT3 inhibition. Accordingly, more apoptotic cells were induced by the dual inhibition of autophagy and STAT3 signaling. In conclusion, our data revealed a protective role of autophagy in the radiosensitizing effects of STAT3 inhibition, and inhibition of both autophagy and STAT3 might be a potential therapeutic strategy to increase the radiosensitivity of glioma cells. - Highlights: • Inactivation of STAT3 signaling radiosensitizes malignant glioma cells. • STAT3 inhibition triggers a significant increase of autophagy flux induced by ionizing radiation in glioma cells. • Suppression of autophagy further strengthens the radiosensitizing effects of STAT3 inhibition in glioma cells. • Dual inhibition of autophagy and STAT3 induce massive apoptotic cells upon exposure to ionizing radiation.

  4. MOLECULAR CHARACTERIZATION OF AUTOPHAGY-RELATED GENE 5 FROM Spodoptera exigua AND EXPRESSION ANALYSIS UNDER VARIOUS STRESS CONDITIONS.

    PubMed

    Liu, Kai-Yu; Xia, Yu-Qian; Zhou, Jing; Chen, Zu-Wen; Lu, Dandan; Zhang, Ning-Zhao; Liu, Xu-Sheng; Ai, Hui; Zhou, Li-Lin

    2016-08-01

    Autophagy is not only involved in development, but also has been proved to attend immune response against invading pathogens. Autophagy protein 5 (ATG5) is an important autophagic protein, which plays a crucial role in autophagosome elongation. Although ATG5 has been well studied in mammal, yeast, and Drosophila, little is known about ATG5 in lepidopteran insects. We cloned putative SeAtg5 gene from Spodoptera exigua larvae by the rapid amplification of cDNA ends method, and its characteristics and the influences of multiple exogenous factors on its expression levels were then investigated. The results showed that the putative S. exigua SeATG5 protein is highly homologous to other insect ATG5 proteins, which has a conserved Pfm domain and multiple phosphorylation sites. Next, fluorescence microscope observation showed that mCherry-SeATG5 was distributed in both nucleus and cytoplasm of Spodoptera litura Sl-HP cells and partially co-localized with BmATG6-GFP, but it almost has no significant co-localization with GFP-HaATG8. Then, the Western blot analysis demonstrated that GFP-SeATG5 conjugated with ATG12. Moreover, real-time PCR revealed that its expression levels significantly increased at the initiation of pupation and the stage of adult. In addition, the expression levels of SeAtg5 can be enhanced by the starvation, UV radiation, and infection of baculovirus and bacterium. However, the expression levels of SeAtg5 decreased at 24 h post treatments in all these treatments except in starvation. These results suggested that SeATG5 might be involved in response of S. exigua under various stress conditions. PMID:27226059

  5. Cloning, expression analysis, and RNA interference study of a HORMA domain containing autophagy-related gene 13 (ATG13) from the coleopteran beetle, Tenebrio molitor

    PubMed Central

    Lee, Jung Hee; Jo, Yong Hun; Patnaik, Bharat Bhusan; Park, Ki Beom; Tindwa, Hamisi; Seo, Gi Won; Chandrasekar, Raman; Lee, Yong Seok; Han, Yeon Soo

    2015-01-01

    Autophagy is a process that is necessary during starvation, as it replenishes metabolic precursors by eliminating damaged organelles. Autophagy is mediated by more than 35 autophagy-related (Atg) proteins that participate in the nucleation, elongation, and curving of the autophagosome membrane. In a pursuit to address the role of autophagy during development and immune resistance of the mealworm beetle, Tenebrio molitor, we screened ATG gene sequences from the whole-larva transcriptome database. We identified a homolog of ATG13 gene in T. molitor (designated as TmATG13) that comprises a cDNA of 1176 bp open reading frame (ORF) encoding a protein of 391 amino acids. Analyses of the structure-specific features of TmAtg13 showed an intrinsically disordered middle and C-terminal region that was rich in regulatory phosphorylation sites. The N-terminal Atg13 domain had a HORMA (Hop1, Rev7, and Mad2) fold containing amino acid residues conserved across the Atg13 insect orthologs. A quantitative reverse-transcription-polymerase chain reaction analysis revealed that TmATG13 was expressed ubiquitously during all developmental stages of the insect. TmATG13 mRNA expression was high in the fat body and gut of the larval and adult stages of the insect. The TmATG13 transcripts were expressed at a high level until 6 days of ovarian development, followed by a significant decline. Silencing of ATG13 transcripts in T. molitor larvae showed a reduced survivability of 39 and 38% in response to Escherichia coli and Staphylococcus aureus infection. Furthermore, the role of TmAtg13 in initiating autophagy as a part of the host cell autophagic complex of the host cells against the intracellular pathogen Listeria monocytogenes is currently under study and will be critical to unfold the structure-function relationships. PMID:26136688

  6. Resveratrol triggers protective autophagy through the ceramide/Akt/mTOR pathway in melanoma B16 cells.

    PubMed

    Wang, Meng; Yu, Teng; Zhu, Chengyao; Sun, Hui; Qiu, Ying; Zhu, Xia; Li, Jinchao

    2014-01-01

    Resveratrol (3,5,4'-trihydroxy-trans-stilbene, RSV), a natural polyphenolic compound, is known as a promising anti-cancer agent. In this study, we showed that RSV could inhibit the growth of B16 cells via induction of apoptosis. Moreover, our results showed for the first time that RSV induced autophagy in B16 cells, which might occur through ceramide accumulation and Akt/mTOR pathway inhibition. Inhibition of autophagy by an autophagic inhibitor 3-methyladenine (3-MA) or si-Beclin 1 enhanced RSV-induced cytotoxicity and apoptosis. Thus, autophagy inhibition represents a promising approach to improve the efficacy of RSV in the treatment of patients with melanoma. PMID:24579778

  7. Autophagy: An Exposing Therapeutic Target in Atherosclerosis.

    PubMed

    Luo, Yun; Lu, Shan; Zhou, Ping; Ai, Qi-Di; Sun, Gui-Bo; Sun, Xiao-Bo

    2016-03-01

    Autophagy is an evolutionarily conserved catabolic process whereby the cytoplasmic contents of a cell are sequestered within autophagosomes through a lysosome-dependent pathway. Increasing evidence shows that this process is of great importance in a wide range of diseases, including atherosclerosis (AS). Autophagy can be modulated in advanced AS plaques by cytokines, reactive lipids, lipopolysaccharides, advanced glycation end products, and microRNAs. Autophagy exerts both protective and detrimental functions in vascular disorders. However, despite an increasing interest in autophagy, it remains an underestimated and overlooked phenomenon in AS. Therefore, the precise role of autophagy and its relationship with apoptosis need to be described. This review highlights recent findings on the autophagy activities and signaling pathways in endothelial cells, macrophages, and smooth muscle cells that are accompanied by apoptosis in AS. We conclude with recent studies on autophagy modulation as a new therapeutic approach to treat AS. PMID:26580134

  8. Molecular cloning and characterization of autophagy-related gene TmATG8 in Listeria-invaded hemocytes of Tenebrio molitor.

    PubMed

    Tindwa, Hamisi; Jo, Yong Hun; Patnaik, Bharat Bhusan; Lee, Yong Seok; Kang, Sang Sun; Han, Yeon Soo

    2015-07-01

    Macroautophagy (hereinafter called autophagy) is a highly regulated process used by eukaryotic cells to digest portions of the cytoplasm that remodels and recycles nutrients and disposes of unwanted cytoplasmic constituents. Currently 36 autophagy-related genes (ATG) and their homologs have been characterized in yeast and higher eukaryotes, including insects. In the present study, we identified and functionally characterized the immune function of an ATG8 homolog in a coleopteran insect, Tenebrio molitor (TmATG8). The cDNA of TmATG8 comprises of an ORF of 363 bp that encodes a protein of 120 amino acid residues. TmATG8 transcripts are detected in all the developmental stages analyzed. TmAtg8 protein contains a highly conserved C-terminal glycine residue (Gly116) and shows high amino acid sequence identity (98%) to its Tribolium castaneum homolog, TcAtg8. Loss of function of TmATG8 by RNAi led to a significant increase in the mortality rates of T. molitor larvae against Listeria monocytogenes. Unlike dsEGFP-treated control larvae, TmATG8-silenced larvae failed to turn-on autophagy in hemocytes after injection with L. monocytogenes. These data suggest that TmATG8 play a role in mediating autophagy-based clearance of Listeria in T. molitor. PMID:25727880

  9. Autophagy is involved in TGF-β1-induced protective mechanisms and formation of cancer-associated fibroblasts phenotype in tumor microenvironment

    PubMed Central

    Liu, Fang-Lan; Mo, En-Pan; Yang, Liu; Du, Jun; Wang, Hong-Sheng; Zhang, Huan; Kurihara, Hiroshi; Xu, Jun; Cai, Shao-Hui

    2016-01-01

    Transforming growth factor-β1 (TGF-β1) present in tumor microenvironment acts in a coordinated fashion to either suppress or promote tumor development. However, the molecular mechanisms underlying the effects of TGF-β1 on tumor microenvironment are not well understood. Our clinical data showed a positive association between TGF-β1 expression and cancer-associated fibroblasts (CAFs) in tumor microenvironment of breast cancer patients. Thus we employed starved NIH3T3 fibroblasts in vitro and 4T1 cells mixed with NIH3T3 fibroblasts xenograft model in vivo to simulate nutritional deprivation of tumor microenvironment to explore the effects of TGF-β1. We demonstrated that TGF-β1 protected NIH3T3 fibroblasts from Star-induced growth inhibition, mitochondrial damage and cell apoptosis. Interestingly, TGF-β1 induced the formation of CAFs phenotype in starvation (Star)-treated NIH3T3 fibroblasts and xenografted Balb/c mice, which promoted breast cancer tumor growth. In both models, autophagy agonist rapamycin increased TGF-β1-induced protective effects and formation of CAFs phenotypes, while autophagy inhibitor 3-methyladenine, Atg5 knockdown or TGF-β type I receptor kinase inhibitor LY-2157299 blocked TGF-β1 induced these effects. Taken together, our results indicated that TGF-β/Smad autophagy was involved in TGF-β1-induced protective effects and formation of CAFs phenotype in tumor microenvironment, which may be used as therapy targets in breast cancer. PMID:26716641

  10. Autophagy is involved in TGF-β1-induced protective mechanisms and formation of cancer-associated fibroblasts phenotype in tumor microenvironment.

    PubMed

    Liu, Fang-Lan; Mo, En-Pan; Yang, Liu; Du, Jun; Wang, Hong-Sheng; Zhang, Huan; Kurihara, Hiroshi; Xu, Jun; Cai, Shao-Hui

    2016-01-26

    Transforming growth factor-β1 (TGF-β1) present in tumor microenvironment acts in a coordinated fashion to either suppress or promote tumor development. However, the molecular mechanisms underlying the effects of TGF-β1 on tumor microenvironment are not well understood. Our clinical data showed a positive association between TGF-β1 expression and cancer-associated fibroblasts (CAFs) in tumor microenvironment of breast cancer patients. Thus we employed starved NIH3T3 fibroblasts in vitro and 4T1 cells mixed with NIH3T3 fibroblasts xenograft model in vivo to simulate nutritional deprivation of tumor microenvironment to explore the effects of TGF-β1. We demonstrated that TGF-β1 protected NIH3T3 fibroblasts from Star-induced growth inhibition, mitochondrial damage and cell apoptosis. Interestingly, TGF-β1 induced the formation of CAFs phenotype in starvation (Star)-treated NIH3T3 fibroblasts and xenografted Balb/c mice, which promoted breast cancer tumor growth. In both models, autophagy agonist rapamycin increased TGF-β1-induced protective effects and formation of CAFs phenotypes, while autophagy inhibitor 3-methyladenine, Atg5 knockdown or TGF-β type I receptor kinase inhibitor LY-2157299 blocked TGF-β1 induced these effects. Taken together, our results indicated that TGF-β/Smad autophagy was involved in TGF-β1-induced protective effects and formation of CAFs phenotype in tumor microenvironment, which may be used as therapy targets in breast cancer. PMID:26716641

  11. Current questions and possible controversies in autophagy

    PubMed Central

    Lindqvist, L M; Simon, A K; Baehrecke, E H

    2015-01-01

    Interest in autophagy has exploded over the last decade, with publications highlighting crosstalk with several other cellular processes including secretion, endocytosis, and cell suicide pathways including apoptosis. Autophagy proteins have also been implicated in other cellular processes independently of their roles in autophagy, creating complexities in the interpretation of autophagy (Atg) mutant gene data. Interestingly, this self-eating process is a survival mechanism that can also promote cell death, but when and how autophagy may ‘switch’ its function is still under debate. Indeed, there are currently many models of how autophagy actually influences cell death. In this review, we highlight some outstanding questions and possible controversies in the autophagy field. PMID:26682061

  12. Autophagy inhibition uncovers the neurotoxic action of the antipsychotic drug olanzapine

    PubMed Central

    Vucicevic, Ljubica; Misirkic-Marjanovic, Maja; Paunovic, Verica; Kravic-Stevovic, Tamara; Martinovic, Tamara; Ciric, Darko; Maric, Nadja; Petricevic, Sasa; Harhaji-Trajkovic, Ljubica; Bumbasirevic, Vladimir; Trajkovic, Vladimir

    2015-01-01

    We investigated the role of autophagy, a controlled cellular self-digestion process, in regulating survival of neurons exposed to atypical antipsychotic olanzapine. Olanzapine induced autophagy in human SH-SY5Y neuronal cell line, as confirmed by the increase in autophagic flux and presence of autophagic vesicles, fusion of autophagosomes with lysosomes, and increase in the expression of autophagy-related (ATG) genes ATG4B, ATG5, and ATG7. The production of reactive oxygen species, but not modulation of the main autophagy repressor MTOR or its upstream regulators AMP-activated protein kinase and AKT1, was responsible for olanzapine-triggered autophagy. Olanzapine-mediated oxidative stress also induced mitochondrial depolarization and damage, and the autophagic clearance of dysfunctional mitochondria was confirmed by electron microscopy, colocalization of autophagosome-associated MAP1LC3B (LC3B henceforth) and mitochondria, and mitochondrial association with the autophagic cargo receptor SQSTM1/p62. While olanzapine-triggered mitochondrial damage was not overtly toxic to SH-SY5Y cells, their death was readily initiated upon the inhibition of autophagy with pharmacological inhibitors, RNA interference knockdown of BECN1 and LC3B, or biological free radical nitric oxide. The treatment of mice with olanzapine for 14 d increased the brain levels of autophagosome-associated LC3B-II and mRNA encoding Atg4b, Atg5, Atg7, Atg12, Gabarap, and Becn1. The administration of the autophagy inhibitor chloroquine significantly increased the expression of proapoptotic genes (Trp53, Bax, Bak1, Pmaip1, Bcl2l11, Cdkn1a, and Cdkn1b) and DNA fragmentation in the frontal brain region of olanzapine-exposed animals. These data indicate that olanzapine-triggered autophagy protects neurons from otherwise fatal mitochondrial damage, and that inhibition of autophagy might unmask the neurotoxic action of the drug. PMID:25551567

  13. Nrf2-Mediated Cardiac Maladaptive Remodeling and Dysfunction in a Setting of Autophagy Insufficiency.

    PubMed

    Qin, Qingyun; Qu, Chen; Niu, Ting; Zang, Huimei; Qi, Lei; Lyu, Linmao; Wang, Xuejun; Nagarkatti, Mitzi; Nagarkatti, Prakash; Janicki, Joseph S; Wang, Xing Li; Cui, Taixing

    2016-01-01

    Nuclear factor erythroid-2-related factor 2 (Nrf2) appears to exert either a protective or detrimental effect on the heart; however, the underlying mechanism remains poorly understood. Herein, we uncovered a novel mechanism for turning off the Nrf2-mediated cardioprotection and switching on Nrf2-mediated cardiac dysfunction. In a murine model of pressure overload-induced cardiac remodeling and dysfunction via transverse aortic arch constriction, knockout of Nrf2 enhanced myocardial necrosis and death rate during an initial stage of cardiac adaptation when myocardial autophagy function is intact. However, knockout of Nrf2 turned out to be cardioprotective throughout the later stage of cardiac maladaptive remodeling when myocardial autophagy function became insufficient. Transverse aortic arch constriction -induced activation of Nrf2 was dramatically enhanced in the heart with impaired autophagy, which is induced by cardiomyocyte-specific knockout of autophagy-related gene (Atg)5. Notably, Nrf2 activation coincided with the upregulation of angiotensinogen (Agt) only in the autophagy-impaired heart after transverse aortic arch constriction. Agt5 and Nrf2 gene loss-of-function approaches in combination with Jak2 and Fyn kinase inhibitors revealed that suppression of autophagy inactivated Jak2 and Fyn and nuclear translocation of Fyn, while enhancing nuclear translocation of Nrf2 and Nrf2-driven Agt expression in cardiomyocytes. Taken together, these results indicate that the pathophysiological consequences of Nrf2 activation are closely linked with the functional integrity of myocardial autophagy during cardiac remodeling. When autophagy is intact, Nrf2 is required for cardiac adaptive responses; however, autophagy impairment most likely turns off Fyn-operated Nrf2 nuclear export thus activating Nrf2-driven Agt transcription, which exacerbates cardiac maladaptation leading to dysfunction. PMID:26573705

  14. Autophagy inhibition induces enhanced proapoptotic effects of ZD6474 in glioblastoma

    PubMed Central

    Shen, J; Zheng, H; Ruan, J; Fang, W; Li, A; Tian, G; Niu, X; Luo, S; Zhao, P

    2013-01-01

    Background: Autophagy is a lysosomal degradation pathway that can provide energy through its recycling mechanism to act as a cytoprotective adaptive response mediating treatment resistance in cancer cells. We investigated the autophagy-inducing effects of ZD6474, a small-molecule inhibitor that blocks activities of vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR), and RET tyrosine kinases. Methods: We investigated the effects of ZD6474 on autophagy in glioblastomas cells. The ZD6474 mechanism of action was determined by western blot. We then examined the impacts of the inhibition of autophagy in combination with ZD6474 on cell apoptosis in vitro. Furthermore, we evaluated the synergistic anticancer activity of combination treatment with an autophagy inhibitor (chloroquine) and ZD6474 in U251 glioblastoma cells xenograft model. Results: ZD6474-induced autophagy was dependent on signalling through the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway. ZD6474-induced autophagy was inhibited by both knockdown of the ATG7 and Beclin 1 gene, essential autophagy genes, and pharmacologic agents (chloroquine and 3-methyalanine) treatment. Both treatments also dramatically sensitised glioblastoma cells to ZD6474-induced apoptosis, decreasing cell viability in vitro. Furthermore, in a xenograft mouse model, combined treatment with ZD6474 and chloroquine significantly inhibited U251 tumour growth, and increased the numbers of apoptotic cells compared with treatment with either agent alone. Conclusion: Autophagy protects glioblastoma cells from the proapoptotic effects of ZD6474, which might contribute to tumour resistance against ZD6474 treatment. PMID:23799852

  15. Autophagy inhibition uncovers the neurotoxic action of the antipsychotic drug olanzapine.

    PubMed

    Vucicevic, Ljubica; Misirkic-Marjanovic, Maja; Paunovic, Verica; Kravic-Stevovic, Tamara; Martinovic, Tamara; Ciric, Darko; Maric, Nadja; Petricevic, Sasa; Harhaji-Trajkovic, Ljubica; Bumbasirevic, Vladimir; Trajkovic, Vladimir

    2014-01-01

    We investigated the role of autophagy, a controlled cellular self-digestion process, in regulating survival of neurons exposed to atypical antipsychotic olanzapine. Olanzapine induced autophagy in human SH-SY5Y neuronal cell line, as confirmed by the increase in autophagic flux and presence of autophagic vesicles, fusion of autophagosomes with lysosomes, and increase in the expression of autophagy-related (ATG) genes ATG4B, ATG5, and ATG7. The production of reactive oxygen species, but not modulation of the main autophagy repressor MTOR or its upstream regulators AMP-activated protein kinase and AKT1, was responsible for olanzapine-triggered autophagy. Olanzapine-mediated oxidative stress also induced mitochondrial depolarization and damage, and the autophagic clearance of dysfunctional mitochondria was confirmed by electron microscopy, colocalization of autophagosome-associated MAP1LC3B (LC3B henceforth) and mitochondria, and mitochondrial association with the autophagic cargo receptor SQSTM1/p62. While olanzapine-triggered mitochondrial damage was not overtly toxic to SH-SY5Y cells, their death was readily initiated upon the inhibition of autophagy with pharmacological inhibitors, RNA interference knockdown of BECN1 and LC3B, or biological free radical nitric oxide. The treatment of mice with olanzapine for 14 d increased the brain levels of autophagosome-associated LC3B-II and mRNA encoding Atg4b, Atg5, Atg7, Atg12, Gabarap, and Becn1. The administration of the autophagy inhibitor chloroquine significantly increased the expression of proapoptotic genes (Trp53, Bax, Bak1, Pmaip1, Bcl2l11, Cdkn1a, and Cdkn1b) and DNA fragmentation in the frontal brain region of olanzapine-exposed animals. These data indicate that olanzapine-triggered autophagy protects neurons from otherwise fatal mitochondrial damage, and that inhibition of autophagy might unmask the neurotoxic action of the drug. PMID:25551567

  16. NAF-1 antagonizes starvation-induced autophagy through AMPK signaling pathway in cardiomyocytes.

    PubMed

    Du, Xiaohong; Xiao, Renjie; Xiao, Fan; Chen, Yong; Hua, Fuzhou; Yu, Shuchun; Xu, Guohai

    2015-07-01

    NAF-1 (nutrient-deprivation autophagy factor-1), an autophagy-related gene-related (ATG) protein, has been implicated in the autophagic pro-survival response. However, its role in autophagy has not been examined in the cardiomyocytes. In this study, we found that nutritional stress (NS) induced by glucose deprivation strongly induced autophagy in cultured neonatal rat cardiomyocytes, which was associated with NAF-1 down-regulation in cardiomyocytes under NS conditions. Furthermore, we demonstrate that ectopic expression of NAF-1 was sufficient to inhibit autophagy in cardiomyocytes under glucose deprivation conditions. Moreover, results of the co-immunoprecipitation assay indicate that NAF-1 antagonized autophagy by promoting the interaction between Beclin1 and Bcl-2 in NS-induced cardiomyocytes. Importantly, our results indicate that overexpression of NAF-1 significantly inhibited AMPK activity and protected cardiomyocytes from NS-induced cell death. Taken together, these data show that ectopic expression of NAF-1 antagonizes the degree of autophagy in cardiomyocytes and enhances cell survival during starvation conditions. PMID:25689847

  17. Evaluation of the anti-inflammatory action of curcumin analog (DM1): Effect on iNOS and COX-2 gene expression and autophagy pathways.

    PubMed

    Paulino, Niraldo; Paulino, Amarilis Scremin; Diniz, Susana N; de Mendonça, Sergio; Gonçalves, Ivair D; Faião Flores, Fernanda; Santos, Reginaldo Pereira; Rodrigues, Carina; Pardi, Paulo Celso; Quincoces Suarez, José Agustin

    2016-04-15

    This work describes the anti-inflammatory effect of the curcumin-analog compound, sodium 4-[5-(4-hydroxy-3-methoxyphenyl)-3-oxo-penta-1,4-dienyl]-2-methoxy-phenolate (DM1), and shows that DM1 modulates iNOS and COX-2 gene expression in cultured RAW 264.7 cells and induces autophagy on human melanoma cell line A375. PMID:27010501

  18. Autophagy inhibitors.

    PubMed

    Pasquier, Benoit

    2016-03-01

    Autophagy is a lysosome-dependent mechanism of intracellular degradation. The cellular and molecular mechanisms underlying this process are highly complex and involve multiple proteins, including the kinases ULK1 and Vps34. The main function of autophagy is the maintenance of cell survival when modifications occur in the cellular environment. During the past decade, extensive studies have greatly improved our knowledge and autophagy has exploded as a research field. This process is now widely implicated in pathophysiological processes such as cancer, metabolic, and neurodegenerative disorders, making it an attractive target for drug discovery. In this review, we will summarize the different types of inhibitors that affect the autophagy machinery and provide some potential therapeutic perspectives. PMID:26658914

  19. Autophagy enforces functional integrity of regulatory T cells by coupling environmental cues and metabolic homeostasis

    PubMed Central

    Wei, Jun; Long, Lingyun; Yang, Kai; Guy, Cliff; Shrestha, Sharad; Chen, Zuojia; Wu, Chuan; Vogel, Peter; Neale, Geoffrey; Green, Douglas R; Chi, Hongbo

    2015-01-01

    Regulatory T (Treg) cells respond to immune and inflammatory signals to mediate immunosuppression, but how functional integrity of Treg cells is maintained under activating environments remains elusive. Here we found that autophagy was active in Treg cells and supported their lineage stability and survival fitness. Treg cell-specific deletion of the essential autophagy gene Atg7 or Atg5 led to loss of Treg cells, increased tumor resistance, and development of inflammatory disorders. Atg7-deficient Treg cells had increased apoptosis and readily lost Foxp3 expression, especially after activation. Mechanistically, autophagy deficiency upregulated mTORC1 and c-Myc function and glycolytic metabolism that contributed to defective Treg function. Therefore, autophagy couples environmental signals and metabolic homeostasis to protect lineage and survival integrity of Treg cells in activating contexts. PMID:26808230

  20. Protective effect of autophagy on human retinal pigment epithelial cells against lipofuscin fluorophore A2E: implications for age-related macular degeneration

    PubMed Central

    Zhang, J; Bai, Y; Huang, L; Qi, Y; Zhang, Q; Li, S; Wu, Y; Li, X

    2015-01-01

    Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly. Degeneration of retinal pigment epithelial (RPE) cells is a crucial causative factor responsible for the onset and progression of AMD. A2E, a major component of toxic lipofuscin implicated in AMD, is deposited in RPE cells with age. However, the mechanism whereby A2E may contribute to the pathogenesis of AMD remains unclear. We demonstrated that A2E was a danger signal of RPE cells, which induced autophagy and decreased cell viability in a concentration- and time-dependent manner. Within 15 min after the treatment of RPE with 25 μM A2E, the induction of autophagosome was detected by transmission electron microscopy. After continuous incubating RPE cells with A2E, intense punctate staining of LC3 and increased expression of LC3-II and Beclin-1 were identified. Meanwhile, the levels of intercellular adhesion molecule (ICAM), interleukin (IL)1β, IL2, IL-6, IL-8, IL-17A, IL-22, macrophage cationic peptide (MCP)-1, stromal cell-derived factor (SDF)-1, and vascular endothelial growth factor A (VEGFA) were elevated. The autophagic inhibitor 3-methyladenine (3-MA) and activator rapamycin were also used to verify the effect of autophagy on RPE cells against A2E. Our results revealed that 3-MA decreased the autophagosomes and LC3 puncta induced by A2E, increased inflammation-associated protein expression including ICAM, IL1β, IL2, IL-6, IL-8, IL-17A, IL-22, and SDF-1, and upregulated VEGFA expression. Whereas rapamycin augmented the A2E-mediated autophagy, attenuated protein expression of inflammation-associated and angiogenic factors, and blocked the Akt/mTOR pathway. Taken together, A2E induces autophagy in RPE cells at the early stage of incubation, and this autophagic response can be inhibited by 3-MA or augmented by rapamycin via the mTOR pathway. The enhancement of autophagy has a protective role in RPE cells against the adverse effects of A2E by reducing the

  1. Protective effect of autophagy on human retinal pigment epithelial cells against lipofuscin fluorophore A2E: implications for age-related macular degeneration.

    PubMed

    Zhang, J; Bai, Y; Huang, L; Qi, Y; Zhang, Q; Li, S; Wu, Y; Li, X

    2015-01-01

    Age-related macular degeneration (AMD) is the leading cause of central vision loss in the elderly. Degeneration of retinal pigment epithelial (RPE) cells is a crucial causative factor responsible for the onset and progression of AMD. A2E, a major component of toxic lipofuscin implicated in AMD, is deposited in RPE cells with age. However, the mechanism whereby A2E may contribute to the pathogenesis of AMD remains unclear. We demonstrated that A2E was a danger signal of RPE cells, which induced autophagy and decreased cell viability in a concentration- and time-dependent manner. Within 15 min after the treatment of RPE with 25 μM A2E, the induction of autophagosome was detected by transmission electron microscopy. After continuous incubating RPE cells with A2E, intense punctate staining of LC3 and increased expression of LC3-II and Beclin-1 were identified. Meanwhile, the levels of intercellular adhesion molecule (ICAM), interleukin (IL)1β, IL2, IL-6, IL-8, IL-17A, IL-22, macrophage cationic peptide (MCP)-1, stromal cell-derived factor (SDF)-1, and vascular endothelial growth factor A (VEGFA) were elevated. The autophagic inhibitor 3-methyladenine (3-MA) and activator rapamycin were also used to verify the effect of autophagy on RPE cells against A2E. Our results revealed that 3-MA decreased the autophagosomes and LC3 puncta induced by A2E, increased inflammation-associated protein expression including ICAM, IL1β, IL2, IL-6, IL-8, IL-17A, IL-22, and SDF-1, and upregulated VEGFA expression. Whereas rapamycin augmented the A2E-mediated autophagy, attenuated protein expression of inflammation-associated and angiogenic factors, and blocked the Akt/mTOR pathway. Taken together, A2E induces autophagy in RPE cells at the early stage of incubation, and this autophagic response can be inhibited by 3-MA or augmented by rapamycin via the mTOR pathway. The enhancement of autophagy has a protective role in RPE cells against the adverse effects of A2E by reducing the

  2. Effects of Atrazine and Chlorpyrifos on Autophagy-Related Genes in the Brain of Common Carp: Health-Risk Assessments.

    PubMed

    Xing, Hou-Juan; Wang, Liang-Liang; Yao, Hai-Dong; Wang, Xiao-Long; Xu, Shi-Wen

    2016-02-01

    This study assessed the impacts of atrazine (ATR), chlorpyrifos (CPF), and a combined ATR/CPF exposure on the brain of common carp (Cyprinus carpio L.). The carp were sampled after a 40-days exposure to CPF and ATR, individually or in combination, followed by a 40-days recovery period to measure autophagy and antioxidant activity. The results indicate that the anti-superoxide anion and anti-hydroxy radical activities decreased upon exposure to ATR, CPF, and the ATR/CPF combination but increased after a subsequent 40-days recovery period. Quantitative real-time PCR and Western blot analyses revealed that the mRNA and protein levels of LC3B and dynein in common carp decreased significantly after exposure to ATR and CPF alone or in combination. Moreover, the mRNA and protein levels of beclin1 gene decreased significantly only in the 116 and 11.3 μg/L treatment groups. However, the mRNA and protein levels of all tested genes increased significantly after a 40-days recovery. Transmission electron microscope demonstrated the occurrence of autolysosomes in the recovery groups but not in the exposure groups. These results suggest that exposure to ATR, CPF, or their combination promotes oxidative stress and autophagic responses in the brain of common carp. PMID:26662364

  3. The role of STAT3 in autophagy

    PubMed Central

    You, Liangkun; Wang, Zhanggui; Li, Hongsen; Shou, Jiawei; Jing, Zhao; Xie, Jiansheng; Sui, Xinbing; Pan, Hongming; Han, Weidong

    2015-01-01

    Autophagy is an evolutionarily conserved process in eukaryotes that eliminates harmful components and maintains cellular homeostasis in response to a series of extracellular insults. However, these insults may trigger the downstream signaling of another prominent stress responsive pathway, the STAT3 signaling pathway, which has been implicated in multiple aspects of the autophagic process. Recent reports further indicate that different subcellular localization patterns of STAT3 affect autophagy in various ways. For example, nuclear STAT3 fine-tunes autophagy via the transcriptional regulation of several autophagy-related genes such as BCL2 family members, BECN1, PIK3C3, CTSB, CTSL, PIK3R1, HIF1A, BNIP3, and microRNAs with targets of autophagy modulators. Cytoplasmic STAT3 constitutively inhibits autophagy by sequestering EIF2AK2 as well as by interacting with other autophagy-related signaling molecules such as FOXO1 and FOXO3. Additionally, the mitochondrial translocation of STAT3 suppresses autophagy induced by oxidative stress and may effectively preserve mitochondria from being degraded by mitophagy. Understanding the role of STAT3 signaling in the regulation of autophagy may provide insight into the classic autophagy model and also into cancer therapy, especially for the emerging targeted therapy, because a series of targeted agents execute antitumor activities via blocking STAT3 signaling, which inevitably affects the autophagy pathway. Here, we review several of the representative studies and the current understanding in this particular field. PMID:25951043

  4. The role of STAT3 in autophagy.

    PubMed

    You, Liangkun; Wang, Zhanggui; Li, Hongsen; Shou, Jiawei; Jing, Zhao; Xie, Jiansheng; Sui, Xinbing; Pan, Hongming; Han, Weidong

    2015-01-01

    Autophagy is an evolutionarily conserved process in eukaryotes that eliminates harmful components and maintains cellular homeostasis in response to a series of extracellular insults. However, these insults may trigger the downstream signaling of another prominent stress responsive pathway, the STAT3 signaling pathway, which has been implicated in multiple aspects of the autophagic process. Recent reports further indicate that different subcellular localization patterns of STAT3 affect autophagy in various ways. For example, nuclear STAT3 fine-tunes autophagy via the transcriptional regulation of several autophagy-related genes such as BCL2 family members, BECN1, PIK3C3, CTSB, CTSL, PIK3R1, HIF1A, BNIP3, and microRNAs with targets of autophagy modulators. Cytoplasmic STAT3 constitutively inhibits autophagy by sequestering EIF2AK2 as well as by interacting with other autophagy-related signaling molecules such as FOXO1 and FOXO3. Additionally, the mitochondrial translocation of STAT3 suppresses autophagy induced by oxidative stress and may effectively preserve mitochondria from being degraded by mitophagy. Understanding the role of STAT3 signaling in the regulation of autophagy may provide insight into the classic autophagy model and also into cancer therapy, especially for the emerging targeted therapy, because a series of targeted agents execute antitumor activities via blocking STAT3 signaling, which inevitably affects the autophagy pathway. Here, we review several of the representative studies and the current understanding in this particular field. PMID:25951043

  5. Autophagy Negatively Regulates Transmissible Gastroenteritis Virus Replication

    PubMed Central

    Guo, Longjun; Yu, Haidong; Gu, Weihong; Luo, Xiaolei; Li, Ren; Zhang, Jian; Xu, Yunfei; Yang, Lijun; Shen, Nan; Feng, Li; Wang, Yue

    2016-01-01

    Autophagy is an evolutionarily ancient pathway that has been shown to be important in the innate immune defense against several viruses. However, little is known about the regulatory role of autophagy in transmissible gastroenteritis virus (TGEV) replication. In this study, we found that TGEV infection increased the number of autophagosome-like double- and single-membrane vesicles in the cytoplasm of host cells, a phenomenon that is known to be related to autophagy. In addition, virus replication was required for the increased amount of the autophagosome marker protein LC3-II. Autophagic flux occurred in TGEV-infected cells, suggesting that TGEV infection triggered a complete autophagic response. When autophagy was pharmacologically inhibited by wortmannin or LY294002, TGEV replication increased. The increase in virus yield via autophagy inhibition was further confirmed by the use of siRNA duplexes, through which three proteins required for autophagy were depleted. Furthermore, TGEV replication was inhibited when autophagy was activated by rapamycin. The antiviral response of autophagy was confirmed by using siRNA to reduce the expression of gene p300, which otherwise inhibits autophagy. Together, the results indicate that TGEV infection activates autophagy and that autophagy then inhibits further TGEV replication. PMID:27029407

  6. MAP1LC3B overexpression protects against Hermansky-Pudlak syndrome type-1-induced defective autophagy in vitro.

    PubMed

    Ahuja, Saket; Knudsen, Lars; Chillappagari, Shashi; Henneke, Ingrid; Ruppert, Clemens; Korfei, Martina; Gochuico, Bernadette R; Bellusci, Saverio; Seeger, Werner; Ochs, Matthias; Guenther, Andreas; Mahavadi, Poornima

    2016-03-15

    Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder, and some patients with HPS develop pulmonary fibrosis, known as HPS-associated interstitial pneumonia (HPSIP). We have previously reported that HPSIP is associated with severe surfactant accumulation, lysosomal stress, and alveolar epithelial cell type II (AECII) apoptosis. Here, we hypothesized that defective autophagy might result in excessive lysosomal stress in HPSIP. Key autophagy proteins, including LC3B lipidation and p62, were increased in HPS1/2 mice lungs. Electron microscopy demonstrated a preferable binding of LC3B to the interior of lamellar bodies in the AECII of HPS1/2 mice, whereas in wild-type mice it was present on the limiting membrane in addition to the interior of the lamellar bodies. Similar observations were noted in human HPS1 lung sections. In vitro knockdown of HPS1 revealed increased LC3B lipidation and p62 accumulation, associated with an increase in proapoptotic caspases. Overexpression of LC3B decreased the HPS1 knockdown-induced p62 accumulation, whereas rapamycin treatment did not show the same effect. We conclude that loss of HPS1 protein results in impaired autophagy that is restored by exogenous LC3B and that defective autophagy might therefore play a critical role in the development and progression of HPSIP. PMID:26719147

  7. Autophagy-related gene 5 and Wnt5 signaling pathway requires differentiation of embryonic stem cells into odontoblast-like cells.

    PubMed

    Ozeki, Nobuaki; Mogi, Makio; Hase, Naoko; Hiyama, Taiki; Yamaguchi, Hideyuki; Kawai, Rie; Kondo, Ayami; Matsumoto, Toru; Nakata, Kazuhiko

    2016-02-01

    We previously confirmed a unique and unanticipated role for an α2 integrin, extracellular matrix metalloproteinase inducer (Emmprin), and matrix metalloproteinase (MMP)-3-mediated signaling cascade, in driving the odontoblast-like differentiation of mouse embryonic stem (ES) cells in a collagen type-I scaffold (CS) combined with bone morphogenetic protein (BMP)-4 (CS/BMP-4). To explore the early signaling cascade for odontoblastic differentiation, we examined the upregulation of autophagy-related gene (Atg) and Wnt signaling by CS/BMP-4 mediated odontoblast differentiation. In a screening experiment, CS/BMP-4 increased the mRNA and protein levels of Atg5, Lrp5/Fzd9 (an Atg5 receptor), and Wnt5, but not microtubule-associated protein 1 light chain (LC3; a mammalian homolog of yeast Atg8), TFE3, Beclin1, and Atg12, together with the amount of autophagosomes and autophagy fluxes. Treatment with siRNAs against Atg5 and Wnt5 individually suppressed the CS/BMP-4-induced increase in odontoblast differentiation. The odontoblastic phenotype, involving dentin matrix protein-1 and dentin sialophosphoprotein expression, decreased when autophagy was inhibited by chloroquine, but increased after treatment with rapamycin (an autophagy enhancer). Taken together with our previous findings, we have revealed a unique sequential cascade involving Atg5, Wnt5a, α2 integrin, Emmprin, and MMP-3. This cascade results in a potent increase in odontoblastic cell differentiation, indicating the unique involvement of Atg5, autophagy and Wnt5 signaling in CS/BMP-4-induced differentiation of ES cells into odontoblast-like cells, at a relatively early stage. PMID:26806855

  8. Repetitive stimulation of autophagy-lysosome machinery by intermittent fasting preconditions the myocardium to ischemia-reperfusion injury.

    PubMed

    Godar, Rebecca J; Ma, Xiucui; Liu, Haiyan; Murphy, John T; Weinheimer, Carla J; Kovacs, Attila; Crosby, Seth D; Saftig, Paul; Diwan, Abhinav

    2015-01-01

    Autophagy, a lysosomal degradative pathway, is potently stimulated in the myocardium by fasting and is essential for maintaining cardiac function during prolonged starvation. We tested the hypothesis that intermittent fasting protects against myocardial ischemia-reperfusion injury via transcriptional stimulation of the autophagy-lysosome machinery. Adult C57BL/6 mice subjected to 24-h periods of fasting, every other day, for 6 wk were protected from in-vivo ischemia-reperfusion injury on a fed day, with marked reduction in infarct size in both sexes as compared with nonfasted controls. This protection was lost in mice heterozygous null for Lamp2 (coding for lysosomal-associated membrane protein 2), which demonstrate impaired autophagy in response to fasting with accumulation of autophagosomes and SQSTM1, an autophagy substrate, in the heart. In lamp2 null mice, intermittent fasting provoked progressive left ventricular dilation, systolic dysfunction and hypertrophy; worsening cardiomyocyte autophagosome accumulation and lack of protection to ischemia-reperfusion injury, suggesting that intact autophagy-lysosome machinery is essential for myocardial homeostasis during intermittent fasting and consequent ischemic cardioprotection. Fasting and refeeding cycles resulted in transcriptional induction followed by downregulation of autophagy-lysosome genes in the myocardium. This was coupled with fasting-induced nuclear translocation of TFEB (transcription factor EB), a master regulator of autophagy-lysosome machinery; followed by rapid decline in nuclear TFEB levels with refeeding. Endogenous TFEB was essential for attenuation of hypoxia-reoxygenation-induced cell death by repetitive starvation, in neonatal rat cardiomyocytes, in-vitro. Taken together, these data suggest that TFEB-mediated transcriptional priming of the autophagy-lysosome machinery mediates the beneficial effects of fasting-induced autophagy in myocardial ischemia-reperfusion injury. PMID:26103523

  9. Tomato HsfA1a plays a critical role in plant drought tolerance by activating ATG genes and inducing autophagy

    PubMed Central

    Wang, Yu; Cai, Shuyu; Yin, Lingling; Shi, Kai; Xia, Xiaojian; Zhou, Yanhong; Yu, Jingquan; Zhou, Jie

    2015-01-01

    Autophagy plays critical roles in plant responses to stress. In contrast to the wealth of information concerning the core process of plant autophagosome assembly, our understanding of the regulation of autophagy is limited. In this study, we demonstrated that transcription factor HsfA1a played a critical role in tomato tolerance to drought stress, in part through its positive role in induction of autophagy under drought stress. HsfA1a expression was induced by drought stress. Virus-induced HsfA1a gene silencing reduced while its overexpression increased plant drought tolerance based on both symptoms and membrane integrity. HsfA1a-silenced plants were more sensitive to endogenous ABA-mediated stomatal closure, while its overexpression lines were resistant under drought stress, indicating that phytohormone ABA did not play a major role in HsfA1a-induced drought tolerance. On the other hand, HsfA1a-silenced plants increased while its overexpression decreased the levels of insoluble proteins which were highly ubiquitinated under drought stress. Furthermore, drought stress induced numerous ATGs expression and autophagosome formation in wild-type plants. The expression of ATG10 and ATG18f, and the formation of autophagosomes were compromised in HsfA1a-silenced plants but were enhanced in HsfA1a-overexpressing plants. Both electrophoretic mobility shift assay and chromatin immunoprecipitation coupled with qPCR analysis revealed that HsfA1a bound to ATG10 and ATG18f gene promoters. Silencing of ATG10 and ATG18f reduced HsfA1a-induced drought tolerance and autophagosome formation in plants overexpressing HsfA1a. These results demonstrate that HsfA1a induces drought tolerance by activating ATG genes and inducing autophagy, which may promote plant survival by degrading ubiquitinated protein aggregates under drought stress. PMID:26649940

  10. Autophagy mediates the mitotic senescence transition

    PubMed Central

    Young, Andrew R.J.; Narita, Masako; Ferreira, Manuela; Kirschner, Kristina; Sadaie, Mahito; Darot, Jeremy F.J.; Tavaré, Simon; Arakawa, Satoko; Shimizu, Shigeomi; Watt, Fiona M.; Narita, Masashi

    2009-01-01

    As a stress response, senescence is a dynamic process involving multiple effector mechanisms whose combination determines the phenotypic quality. Here we identify autophagy as a new effector mechanism of senescence. Autophagy is activated during senescence and its activation is correlated with negative feedback in the PI3K–mammalian target of rapamycin (mTOR) pathway. A subset of autophagy-related genes are up-regulated during senescence: Overexpression of one of those genes, ULK3, induces autophagy and senescence. Furthermore, inhibition of autophagy delays the senescence phenotype, including senescence-associated secretion. Our data suggest that autophagy, and its consequent protein turnover, mediate the acquisition of the senescence phenotype. PMID:19279323

  11. Dysregulation of Autophagy, Mitophagy, and Apoptotic Genes in the Medial Temporal Lobe Cortex in an Ischemic Model of Alzheimer’s Disease

    PubMed Central

    Ułamek-Kozioł, Marzena; Kocki, Janusz; Bogucka-Kocka, Anna; Petniak, Alicja; Gil-Kulik, Paulina; Januszewski, Sławomir; Bogucki, Jacek; Jabłoński, Mirosław; Furmaga-Jabłońska, Wanda; Brzozowska, Judyta; Czuczwar, Stanisław J.; Pluta, Ryszard

    2016-01-01

    Ischemic brain damage is a pathological incident that is often linked with medial temporal lobe cortex injury and finally its atrophy. Post-ischemic brain injury associates with poor prognosis since neurons of selectively vulnerable ischemic brain areas are disappearing by apoptotic program of neuronal death. Autophagy has been considered, after brain ischemia, as a guardian against neurodegeneration. Consequently, we have examined changes in autophagy (BECN 1), mitophagy (BNIP 3), and apoptotic (caspase 3) genes in the medial temporal lobe cortex with the use of quantitative reverse-transcriptase PCR following transient 10-min global brain ischemia in rats with survival 2, 7, and 30 days. The intense significant overexpression of BECN 1 gene was noted on the 2nd day, while on days 7–30 the expression of this gene was still upregulated. BNIP 3 gene was downregulated on the 2nd day, but on days 7–30 post-ischemia, there was a significant reverse tendency. Caspase 3 gene, associated with apoptotic neuronal death, was induced in the same way as BNIP 3 gene after brain ischemia. Thus, the demonstrated changes indicate that the considerable dysregulation of expression of BECN 1, BNIP 3, and caspase 3 genes may be connected with a response of neuronal cells in medial temporal lobe cortex to transient complete brain ischemia. PMID:27472881

  12. Oxidative stress-induced autophagy: Role in pulmonary toxicity

    SciTech Connect

    Malaviya, Rama; Laskin, Jeffrey D.; Laskin, Debra L.

    2014-03-01

    Autophagy is an evolutionarily conserved catabolic process important in regulating the turnover of essential proteins and in elimination of damaged organelles and protein aggregates. Autophagy is observed in the lung in response to oxidative stress generated as a consequence of exposure to environmental toxicants. Whether autophagy plays role in promoting cell survival or cytotoxicity is unclear. In this article recent findings on oxidative stress-induced autophagy in the lung are reviewed; potential mechanisms initiating autophagy are also discussed. A better understanding of autophagy and its role in pulmonary toxicity may lead to the development of new strategies to treat lung injury associated with oxidative stress. - Highlights: • Exposure to pulmonary toxicants is associated with oxidative stress. • Oxidative stress is known to induce autophagy. • Autophagy is upregulated in the lung following exposure to pulmonary toxicants. • Autophagy may be protective or pathogenic.

  13. Do Genes That Protect Against Dementia Guard Against Chronic Diseases?

    MedlinePlus

    ... nih.gov/medlineplus/news/fullstory_158442.html Do Genes That Protect Against Dementia Guard Against Chronic Diseases? ... Services, or federal policy. More Health News on: Genes and Gene Therapy Healthy Aging Seniors' Health Recent ...

  14. A polymorphism in an autophagy-related gene, ATG16L1, influences time to delivery in women with an unfavorable cervix who require labor induction.

    PubMed

    Doulaveris, Georgios; Orfanelli, Theofano; Benn, Kiesha; Zervoudakis, Ioannis; Skupski, Daniel; Witkin, Steven S

    2013-07-01

    Autophagy is an intracellular process that maintains homeostasis by the removal of damaged organelles and proteins. A single nucleotide polymorphism (SNP) in the autophagy-related 16-like 1 (ATG16L1) gene results in decreased autophagy. We evaluated whether the ATG16L1 polymorphism influenced the time to delivery during labor induction in pregnant women with an unfavorable cervix. DNA from 69 women with an unfavorable cervix who required labor induction due to post-term (>294 days) (n=26), oligohydramnios (n=17), hypertension or pre-eclampsia (n=10), abnormal fetal heart rate (n=8), diabetes (n=3) or other reasons (n=5) was tested by gene amplification and endonuclease digestion for a SNP in ATG16L1 (rs2241880). The mean hours (SD) from induction to delivery was 20.8 (9.7) for women who were A,A homozygotes, 19.2 (8.8) for A,G heterozygotes and 14.3 (6.6) for homozygote carriers of the G,G variant (P=0.03 A,A vs. G,G, P=0.04 A,A/A,G vs. G,G). The G,G prevalence was 24.4% and 4.2% for those who delivered in ≤24 and >24 h, respectively (P=0.04). There was no difference in genotype distribution by indication for induction. A decreased genetic capacity for autophagy may be beneficial in women with an unfavorable cervix whose labor has to be induced. PMID:23633462

  15. AMBRA1-regulated autophagy in vertebrate development.

    PubMed

    Antonioli, Manuela; Albiero, Federica; Fimia, Gian María; Piacentini, Mauro

    2015-01-01

    Autophagy is a catabolic process that mediates the lysosomal turn over of organelles and macromolecules, and is strongly activated in stress conditions to ensure cell survival. Autophagy core genes are highly conserved from yeast to mammals, with an increasing number of positive and negative regulators that have evolved in higher eukaryotes. Autophagy takes part in different stages of development, as revealed by alterations in cell proliferation, differentiation and survival during the embryogenesis of organisms carrying mutations in autophagy genes. These defects are ascribed to the ability of autophagy to provide elements for new synthesis or energy production in limiting conditions during embryogenesis, as well as to contribute to the profound cell remodeling that occurs during differentiation. However, many differences have been observed in the phenotypes of autophagy mutant organisms, indicating that these genes have acquired specific functions in particular tissues, which may reflect the ability of autophagy to crosstalk with the main developmental processes. In this review, we discuss the role of upstream regulators of autophagy in the development of different model systems, focusing, in particular, on AMBRA1 (autophagy/beclin-1 regulator-1) and its role in the central nervous system. PMID:26374532

  16. Enhanced autophagy in cytarabine arabinoside-resistant U937 leukemia cells and its potential as a target for overcoming resistance

    PubMed Central

    CHEONG, JUNE-WON; KIM, YUNDEOK; EOM, JU IN; JEUNG, HOI-KYUNG; MIN, YOO HONG

    2016-01-01

    Autophagy is a lysosomal degradation mechanism that is essential for cell survival, differentiation, development, and homeostasis. Autophagy protects cells from various stresses, including protecting normal cells from harmful metabolic conditions, and cancer cells from chemotherapeutics. In the current study, a cytarabine arabinoside (Ara-C)-sensitive U937 leukemia cell line and an Ara-C-resistant U937 (U937/AR) cell line were assessed for baseline autophagy activity by investigating the LC3-I conversion to LC3-II, performing EGFP-LC3 puncta, an acidic autophagolysosome assay, and measuring the expression of various autophagy-related genes. The results demonstrated significantly higher autophagic activity in the U937/AR cells compared with the U937 cells, when the cells were cultured with or without serum. Furthermore, an increase in the autophagic activity in starved U937/AR cells was demonstrated, compared with that in the starved U937 cells. Administration of an autophagy inhibitor demonstrated no change in cell death in the two cell lines when cultured with serum, however, it induced cell death regardless of the Ara-C sensitivity when the cell lines were cultured without serum. In addition, the U937 cells demonstrated an Ara-C resistance when cultured without serum. Co-treatment with Ara-C and the autophagy inhibitor significantly induced cell death in the U937/AR and Ara-C-sensitive U937 cells. In conclusion, autophagy serves an important role in protecting U937 cells from Ara-C and in the development of Ara-C resistance. Inhibition of autophagy combined with the Ara-C treatment in the U937 cells augmented the anti-leukemic effect of Ara-C and overcame Ara-C resistance, suggesting that autophagy may be an important therapeutic target to further improve the treatment outcome in patients with acute myeloid leukemia. PMID:26935591

  17. Vitamin D Receptor Activation Protects Against Myocardial Reperfusion Injury Through Inhibition of Apoptosis and Modulation of Autophagy

    PubMed Central

    Yao, Tianbao; Ying, Xiaoying; Zhao, Yichao; Yuan, Ancai; He, Qing; Tong, Huan; Ding, Song; Liu, Junling; Peng, Xu; Gao, Erhe

    2015-01-01

    Abstract Aims: To determine the roles of vitamin D receptor (VDR) in ischemia/reperfusion-induced myocardial injury and to investigate the underlying mechanisms involved. Results: The endogenous VDR expression was detected in the mouse heart, and myocardial ischemia/reperfusion (MI/R) upregulated VDR expression. Activation of VDR by natural and synthetic agonists reduced myocardial infarct size and improved cardiac function. Mechanistically, VDR activation inhibited endoplasmic reticulum (ER) stress (determined by the reduction of CCAAT/enhancer-binding protein homologous protein expression and caspase-12 activation), attenuated mitochondrial impairment (determined by the decrease of mitochondrial cytochrome c release and caspase-9 activation), and reduced cardiomyocyte apoptosis. Furthermore, VDR activation significantly inhibited MI/R-induced autophagy dysfunction (determined by the inhibition of Beclin 1 over-activation, the reduction of autophagosomes, the LC3-II/LC3-I ratio, p62 protein abundance, and the restoration of autophagy flux). Moreover, VDR activation inhibited MI/R-induced oxidative stress through a metallothionein-dependent mechanism. The cardioprotective effects of VDR agonists mentioned earlier were impaired in the setting of cardiac-specific VDR silencing. In contrast, adenovirus-mediated cardiac VDR overexpression decreased myocardial infarct size and improved cardiac function through attenuating oxidative stress, and inhibiting apoptosis and autophagy dysfunction. Innovation and Conclusion: Our data demonstrate that VDR is a novel endogenous self-defensive and cardioprotective receptor against MI/R injury, via mechanisms (at least in part) reducing oxidative stress, and inhibiting apoptosis and autophagy dysfunction-mediated cell death. Antioxid. Redox Signal. 22, 633–650. PMID:25365634

  18. Autophagy in inflammation, infection, neurodegeneration and cancer

    PubMed Central

    Arroyo, Daniela S.; Gaviglio, Emilia A.; Peralta-Ramos, Javier M.; Bussi, Claudio; Rodriguez-Galan, Maria C.; Iribarren, Pablo

    2014-01-01

    In its classical form, autophagy is an essential, homeostatic process by which cytoplasmic components are degraded in a double-membrane-bound autophagosome in response to starvation. Paradoxically, although autophagy is primarily a protective process for the cell, it can also play a role in cell death. The roles of autophagy bridge both the innate and adaptive immune systems and autophagic dysfunction is associated with inflammation, infection, neurodegeneration and cancer. In this review, we discuss the contribution of autophagy to inflammatory, infectious and neurodegenerative diseases, as well as cancer. PMID:24262302

  19. The roles of macrophage autophagy in atherosclerosis

    PubMed Central

    Shao, Bo-zong; Han, Bin-ze; Zeng, Yan-xia; Su, Ding-feng; Liu, Chong

    2016-01-01

    Although various types of drugs and therapies are available to treat atherosclerosis, it remains a major cause of mortality throughout the world. Macrophages are the major source of foam cells, which are hallmarks of atherosclerotic lesions. Consequently, the roles of macrophages in the pathophysiology of atherosclerosis are increasingly investigated. Autophagy is a self-protecting cellular catabolic pathway. Since its discovery, autophagy has been found to be associated with a variety of diseases, including cardiovascular diseases, malignant tumors, neurodegenerative diseases, and immune system disorders. Accumulating evidence demonstrates that autophagy plays an important role in inhibiting inflammation and apoptosis, and in promoting efferocytosis and cholesterol efflux. These facts suggest the induction of autophagy may be exploited as a potential strategy for the treatment of atherosclerosis. In this review we mainly discuss the relationship between macrophage autophagy and atherosclerosis and the molecular mechanisms, as well as the recent advances in targeting the process of autophagy to treat atherosclerosis. PMID:26750103

  20. Suppression of Bim by microRNA-19a may protect cardiomyocytes against hypoxia-induced cell death via autophagy activation.

    PubMed

    Gao, Yan-Hua; Qian, Ju-Ying; Chen, Zhang-Wei; Fu, Ming-Qiang; Xu, Jian-Feng; Xia, Yan; Ding, Xue-Feng; Yang, Xiang-Dong; Cao, Yuan-Yuan; Zou, Yun-Zeng; Ren, Jun; Sun, Ai-Jun; Ge, Jun-Bo

    2016-08-22

    Microvascular obstruction (MO), one of unfavorable complications of percutaneous coronary intervention (PCI), is responsible for the lost benefit of reperfusion therapy. Determination of microRNA-19a, a member of the miR-17-92 cluster, using quantitative real-time polymerase chain reaction (PCR) revealed notably down-regulated microRNA-19a, in myocardium with MO. Nonetheless, the role of miR-19a in MO and the underlying mechanism remains to be elucidated. To this end, an in vitro microembolization model in cardiomyocytes was used. Our data revealed that hypoxic exposure prompted cardiomyocyte apoptosis in a time-dependent manner accompanied by reduced miR-19a. miR-19a overexpression clearly ameliorated hypoxia-induced cell death (necrosis and apoptosis), at least in part, through switching on autophagy. Further dual-luciferase reporter assay and immunoblotting studies demonstrated that miR-19a-induced cytoprotection might be achieved in part through modulation of the specific target Bcl-2 interacting mediator of cell death, Bim, an apoptotic activator. Bim sufficiently interfered with miR-19a-induced LC3 conversion and increased cardiomyocyte apoptosis under hypoxia. Moreover, cardiomyocytes pretreated with 3-methyladenine conferred resistance to the cytoprotective effect of miR-19a and displayed notably increased TUNEL staining and caspase-3 activity. In conclusion, miR-19a protected cardiomyocytes against hypoxia-induced lethality at least in part via Bim suppression and subsequently autophagy activation. PMID:27220268

  1. The LRRK2 inhibitor GSK2578215A induces protective autophagy in SH-SY5Y cells: involvement of Drp-1-mediated mitochondrial fission and mitochondrial-derived ROS signaling

    PubMed Central

    Saez-Atienzar, S; Bonet-Ponce, L; Blesa, J R; Romero, F J; Murphy, M P; Jordan, J; Galindo, M F

    2014-01-01

    Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene have been associated with Parkinson's disease, and its inhibition opens potential new therapeutic options. Among the drug inhibitors of both wild-type and mutant LRRK2 forms is the 2-arylmethyloxy-5-subtitutent-N-arylbenzamide GSK257815A. Using the well-established dopaminergic cell culture model SH-SY5Y, we have investigated the effects of GSK2578215A on crucial neurodegenerative features such as mitochondrial dynamics and autophagy. GSK2578215A induces mitochondrial fragmentation of an early step preceding autophagy. This increase in autophagosome results from inhibition of fusion rather than increases in synthesis. The observed effects were shared with LRRK2-IN-1, a well-described, structurally distinct kinase inhibitor compound or when knocking down LRRK2 expression using siRNA. Studies using the drug mitochondrial division inhibitor 1 indicated that translocation of the dynamin-related protein-1 has a relevant role in this process. In addition, autophagic inhibitors revealed the participation of autophagy as a cytoprotective response by removing damaged mitochondria. GSK2578215A induced oxidative stress as evidenced by the accumulation of 4-hydroxy-2-nonenal in SH-SY5Y cells. The mitochondrial-targeted reactive oxygen species scavenger MitoQ positioned these species as second messengers between mitochondrial morphologic alterations and autophagy. Altogether, our results demonstrated the relevance of LRRK2 in mitochondrial-activated pathways mediating in autophagy and cell fate, crucial features in neurodegenerative diseases. PMID:25118928

  2. Mechanism of action of the tuberculosis and Crohn disease risk factor IRGM in autophagy.

    PubMed

    Chauhan, Santosh; Mandell, Michael A; Deretic, Vojo

    2016-01-01

    Polymorphisms in the IRGM gene, associated with Crohn disease (CD) and tuberculosis, are among the earliest identified examples documenting the role of autophagy in human disease. Functional studies have shown that IRGM protects against these diseases by modulating autophagy, yet the exact molecular mechanism of IRGM's activity has remained unknown. We have recently elucidated IRGM's mechanism of action. IRGM functions as a platform for assembling, stabilizing, and activating the core autophagic machinery, while at the same time physically coupling it to conventional innate immunity receptors. Exposure to microbial products or bacterial invasion increases IRGM expression, which leads to stabilization of AMPK. Specific protein-protein interactions and post-translational modifications such as ubiquitination of IRGM, lead to a co-assembly with IRGM of the key autophagy regulators ULK1 and BECN1 in their activated forms. IRGM physically interacts with 2 other CD risk factors, ATG16L1 and NOD2, placing these 3 principal players in CD within the same molecular complex. This explains how polymorphisms altering expression or function of any of the 3 factors individually can affect the same process-autophagy. Furthermore, IRGM's interaction with NOD2, and additional pattern recognition receptors such as NOD1, RIG-I, and select TLRs, transduces microbial signals to the core autophagy apparatus. This work solves the long-standing enigma of how IRGM controls autophagy. PMID:26313894

  3. Role of autophagy in cadmium-induced apoptosis of primary rat osteoblasts

    PubMed Central

    Liu, Wei; Dai, Nannan; Wang, Yi; Xu, Chao; Zhao, Hongyan; Xia, Pengpeng; Gu, Jianhong; Liu, Xuezhong; Bian, Jianchun; Yuan, Yan; Zhu, Jiaqiao; Liu, Zongping

    2016-01-01

    Cadmium (Cd) is a common environmental pollutant that can damage many organs and the fetus. We previously reported that Cd induced apoptosis in primary rat osteoblasts (OBs). OB apoptosis induced by Cd will eventually lead to osteoporosis. In this study, a novel pharmacotherapeutic approach was investigated involving the regulation of autophagy to prevent Cd osteoporosis. The results showed that Cd treatment induced apoptosis in OBs, as demonstrated by the ratio of Bax/Bcl-2, activation of poly (ADP-ribose) polymerase (PARP) and nuclear condensation. In addition, cells treated with Cd were observed to undergo autophagic cell death by monitoring the induction of the beclin 1, autophagy gene 5 (Atg5) and the expression of microtubule-associated protein 1 light chain 3 (LC3). The results indicated that promotion of apoptotic cell death by Cd is accompanied by induction of autophagy in OBs. Interestingly, Cd-mediated apoptotic cell death was suppressed by pretreatment with the autophagy activator rapamycin (RAP) and potentiated by the autophagy inhibitor chloroquine (CQ) or small interfering RNA against beclin 1. These findings suggest that the autophagic response plays a protective role that impedes eventual cell death. Activation of autophagy could therefore be an adjunctive strategy for treatment of Cd-induced osteoporosis. PMID:26852917

  4. Role of autophagy in cadmium-induced apoptosis of primary rat osteoblasts.

    PubMed

    Liu, Wei; Dai, Nannan; Wang, Yi; Xu, Chao; Zhao, Hongyan; Xia, Pengpeng; Gu, Jianhong; Liu, Xuezhong; Bian, Jianchun; Yuan, Yan; Zhu, Jiaqiao; Liu, Zongping

    2016-01-01

    Cadmium (Cd) is a common environmental pollutant that can damage many organs and the fetus. We previously reported that Cd induced apoptosis in primary rat osteoblasts (OBs). OB apoptosis induced by Cd will eventually lead to osteoporosis. In this study, a novel pharmacotherapeutic approach was investigated involving the regulation of autophagy to prevent Cd osteoporosis. The results showed that Cd treatment induced apoptosis in OBs, as demonstrated by the ratio of Bax/Bcl-2, activation of poly (ADP-ribose) polymerase (PARP) and nuclear condensation. In addition, cells treated with Cd were observed to undergo autophagic cell death by monitoring the induction of the beclin 1, autophagy gene 5 (Atg5) and the expression of microtubule-associated protein 1 light chain 3 (LC3). The results indicated that promotion of apoptotic cell death by Cd is accompanied by induction of autophagy in OBs. Interestingly, Cd-mediated apoptotic cell death was suppressed by pretreatment with the autophagy activator rapamycin (RAP) and potentiated by the autophagy inhibitor chloroquine (CQ) or small interfering RNA against beclin 1. These findings suggest that the autophagic response plays a protective role that impedes eventual cell death. Activation of autophagy could therefore be an adjunctive strategy for treatment of Cd-induced osteoporosis. PMID:26852917

  5. Disruption of autophagy by the histone deacetylase inhibitor MGCD0103 and its therapeutic implication in B-cell chronic lymphocytic leukemia

    PubMed Central

    El-Khoury, V; Pierson, S; Szwarcbart, E; Brons, N H C; Roland, O; Cherrier-De Wilde, S; Plawny, L; Van Dyck, E; Berchem, G

    2014-01-01

    Evading apoptosis is a hallmark of B-cell chronic lymphocytic leukemia (CLL) cells and an obstacle to current chemotherapeutic approaches. Inhibiting histone deacetylase (HDAC) has emerged as a promising strategy to induce cell death in malignant cells. We have previously reported that the HDAC inhibitor MGCD0103 induces CLL cell death by activating the intrinsic pathway of apoptosis. Here, we show that MGCD0103 decreases the autophagic flux in primary CLL cells. Activation of the PI3K/AKT/mTOR pathway, together with the activation of caspases, and to a minor extent CAPN1, resulting in cleavage of autophagy components, were involved in MGCD0103-mediated inhibition of autophagy. In addition, MGCD0103 directly modulated the expression of critical autophagy genes at the transcriptional level that may contribute to autophagy impairment. Besides, we demonstrate that autophagy is a pro-survival mechanism in CLL whose disruption potentiates cell death induced by anticancer molecules including HDAC and cyclin-dependent kinase inhibitors. In particular, our data highlight the therapeutic potential of MGCD0103 as not only an inducer of apoptosis but also an autophagy suppressor in both combination regimens with molecules like flavopiridol, known to induce protective autophagy in CLL cells, or as an alternative to circumvent undesired immunomodulatory effects seen in the clinic with conventional autophagy inhibitors. PMID:24418989

  6. Autophagy: an emerging therapeutic target in vascular diseases

    PubMed Central

    Vindis, Cécile

    2015-01-01

    Autophagy is a cellular catabolic process responsible for the destruction of long-lived proteins and organelles via lysosome-dependent pathway. This process is of great importance in maintaining cellular homeostasis, and deregulated autophagy has been implicated in the pathogenesis of a wide range of diseases. A growing body of evidence suggests that autophagy can be activated in vascular disorders such as atherosclerosis. Autophagy occurs under basal conditions and mediates homeostatic functions in cells but in the setting of pathological states up-regulated autophagy can exert both protective and detrimental functions. Therefore, the precise role of autophagy and its relationship with the progression of the disease need to be clarified. This review highlights recent findings regarding autophagy activity in vascular cells and its potential contribution to vascular disorders with a focus on atherogenesis. Finally, whether the manipulation of autophagy represents a new therapeutic approach to treat or prevent vascular diseases is also discussed. PMID:25537552

  7. Do Genes That Protect Against Dementia Guard Against Chronic Diseases?

    MedlinePlus

    ... suggest that protection against cognitive decline contributes to healthy aging." Schadt is enthusiastic about the research team's work. " ... More Health News on: Genes and Gene Therapy Healthy Aging Seniors' Health Recent Health News Related MedlinePlus Health ...

  8. FGF signalling regulates bone growth through autophagy.

    PubMed

    Cinque, Laura; Forrester, Alison; Bartolomeo, Rosa; Svelto, Maria; Venditti, Rossella; Montefusco, Sandro; Polishchuk, Elena; Nusco, Edoardo; Rossi, Antonio; Medina, Diego L; Polishchuk, Roman; De Matteis, Maria Antonietta; Settembre, Carmine

    2015-12-10

    Skeletal growth relies on both biosynthetic and catabolic processes. While the role of the former is clearly established, how the latter contributes to growth-promoting pathways is less understood. Macroautophagy, hereafter referred to as autophagy, is a catabolic process that plays a fundamental part in tissue homeostasis. We investigated the role of autophagy during bone growth, which is mediated by chondrocyte rate of proliferation, hypertrophic differentiation and extracellular matrix (ECM) deposition in growth plates. Here we show that autophagy is induced in growth-plate chondrocytes during post-natal development and regulates the secretion of type II collagen (Col2), the major component of cartilage ECM. Mice lacking the autophagy related gene 7 (Atg7) in chondrocytes experience endoplasmic reticulum storage of type II procollagen (PC2) and defective formation of the Col2 fibrillary network in the ECM. Surprisingly, post-natal induction of chondrocyte autophagy is mediated by the growth factor FGF18 through FGFR4 and JNK-dependent activation of the autophagy initiation complex VPS34-beclin-1. Autophagy is completely suppressed in growth plates from Fgf18(-/-) embryos, while Fgf18(+/-) heterozygous and Fgfr4(-/-) mice fail to induce autophagy during post-natal development and show decreased Col2 levels in the growth plate. Strikingly, the Fgf18(+/-) and Fgfr4(-/-) phenotypes can be rescued in vivo by pharmacological activation of autophagy, pointing to autophagy as a novel effector of FGF signalling in bone. These data demonstrate that autophagy is a developmentally regulated process necessary for bone growth, and identify FGF signalling as a crucial regulator of autophagy in chondrocytes. PMID:26595272

  9. Depletion of autophagy-related genes ATG3 and ATG5 in Tenebrio molitor leads to decreased survivability against an intracellular pathogen, Listeria monocytogenes.

    PubMed

    Tindwa, Hamisi; Jo, Yong Hun; Patnaik, Bharat Bhusan; Noh, Mi Young; Kim, Dong Hyun; Kim, Iksoo; Han, Yeon Soo; Lee, Yong Seok; Lee, Bok Luel; Kim, Nam Jung

    2015-01-01

    Macroautophagy (autophagy) is an evolutionarily conserved catabolic process involved in physiological and developmental processes including cell survival, death, and innate immunity. Homologues of most of 36 originally discovered autophagy-related (ATG) genes in yeast have been characterized in higher eukaryotes including insects. In this study, the homologues of ATG3 (TmATG3) and ATG5 (TmATG5) were isolated from the coleopteran beetle, Tenebrio molitor by expressed sequence tag and RNAseq approaches. The cDNA of TmATG3 and TmATG5 comprise open-reading frame sizes of 963 and 792 bp encoding polypeptides of 320 and 263 amino acid residues, respectively. TmATG3 and TmATG5 mRNA are expressed in all developmental stages, and mainly in fat body and hemocytes of larvae. TmATG3 and TmATG5 showed an overall sequence identity of 58-95% to other insect Atg proteins. There exist clear one-to-one orthologs of TmATG3 and TmATG5 in Tribolium and that they clustered together in the gene tree. Depletion of TmATG3 and TmATG5 by RNA interference led to a significant reduction in survival ability of T. molitor larvae against an intracellular pathogen, Listeria monocytogenes. Six days post-Listeria challenge, the survival rate in the dsEGFP-injected (where EGFP is enhanced green fluorescent protein) control larvae was significantly higher (55%) compared to 4 and 3% for TmATG3 and TmATG5 double-stranded RNA injected larvae, respectively. These data suggested that TmATG3 and TmATG5 may play putative role in mediating autophagy-based clearance of Listeria in T. molitor model. PMID:25403020

  10. Circulating Autoantibodies in Age-Related Macular Degeneration Recognize Human Macular Tissue Antigens Implicated in Autophagy, Immunomodulation, and Protection from Oxidative Stress and Apoptosis

    PubMed Central

    Iannaccone, Alessandro; Giorgianni, Francesco; New, David D.; Hollingsworth, T. J.; Umfress, Allison; Alhatem, Albert H.; Neeli, Indira; Lenchik, Nataliya I.; Jennings, Barbara J.; Calzada, Jorge I.; Satterfield, Suzanne; Mathews, Dennis; Diaz, Rocio I.; Harris, Tamara; Johnson, Karen C.; Charles, Steve; Kritchevsky, Stephen B.; Gerling, Ivan C.; Beranova-Giorgianni, Sarka; Radic, Marko Z.

    2015-01-01

    role of inflammation and the immune system in AMD pathogenesis, AAbs were identified in AMD sera, including early-stage disease. Identified targets may be mechanistically linked to AMD pathogenesis because the identified proteins are implicated in autophagy, immunomodulation, and protection from oxidative stress and apoptosis. In particular, a role in autophagy activation is shared by all five autoantigens, raising the possibility that the detected AAbs may play a role in AMD via autophagy compromise and downstream activation of the inflammasome. Thus, we propose that the detected AAbs provide further insight into AMD pathogenesis and have the potential to contribute to disease biogenesis and progression. PMID:26717306

  11. Molecular Mechanisms and Physiological Significance of Autophagy during Myocardial Ischemia and Reperfusion

    PubMed Central

    Matsui, Yutaka; Kyoi, Shiori; Takagi, Hiromitsu; Hsu, Chiao-Po; Hariharan, Nirmala; Ago, Tetsuro; Vatner, Stephen F; Sadoshima, Junichi

    2009-01-01

    Autophagy is an intracellular bulk degradation process whereby cytoplasmic proteins and organelles are degraded and recycled through lysosomes. In the heart, autophagy plays a homeostatic role at basal levels, and the absence of autophagy causes cardiac dysfunction and the development of cardiomyopathy. Autophagy is induced during myocardial ischemia and further enhanced by reperfusion. Although induction of autophagy during the ischemic phase is protective, further enhancement of autophagy during the reperfusion phase may induce cell death and appears to be detrimental. In this review we discuss the functional significance of autophagy and the underlying signaling mechanism in the heart during ischemia/reperfusion. PMID:18227645

  12. NOX4 mediates cytoprotective autophagy induced by the EGFR inhibitor erlotinib in head and neck cancer cells

    SciTech Connect

    Sobhakumari, Arya; Schickling, Brandon M.; Love-Homan, Laurie; Raeburn, Ayanna; Fletcher, Elise V.M.; Case, Adam J.; Domann, Frederick E.; Miller, Francis J.; and others

    2013-11-01

    Most head and neck squamous cell carcinomas (HNSCCs) overexpress epidermal growth factor receptor (EGFR) and EGFR inhibitors are routinely used in the treatment of HNSCC. However, many HNSCC tumors do not respond or become refractory to EGFR inhibitors. Autophagy, which is a stress-induced cellular self-degradation process, has been reported to reduce the efficacy of chemotherapy in various disease models. The purpose of this study is to determine if the efficacy of the EGFR inhibitor erlotinib is reduced by activation of autophagy via NOX4-mediated oxidative stress in HNSCC cells. Erlotinib induced the expression of the autophagy marker LC3B-II and autophagosome formation in FaDu and Cal-27 cells. Inhibition of autophagy by chloroquine and knockdown of autophagy pathway genes Beclin-1 and Atg5 sensitized both cell lines to erlotinib-induced cytotoxicity, suggesting that autophagy may serve as a protective mechanism. Treatment with catalase (CAT) and diphenylene iodonium (DPI) in the presence of erlotinib suppressed the increase in LC3B-II expression in FaDu and Cal-27 cells. Erlotinib increased NOX4 mRNA and protein expression by increasing its promoter activity and mRNA stability in FaDu cells. Knockdown of NOX4 using adenoviral siNOX4 partially suppressed erlotinib-induced LC3B-II expression, while overexpression of NOX4 increased expression of LC3B-II. These studies suggest that erlotinib may activate autophagy in HNSCC cells as a pro-survival mechanism, and NOX4 may play a role in mediating this effect. - Highlights: • Erlotinib increased LC3B-II and autophagosome formation in HNSCC cells. • Inhibition of autophagy sensitized HNSCC cells to erlotinib. • Erlotinib increased NOX4 promoter and 3′UTR luciferase activity. • Manipulating NOX4 decreases or increases autophagy.

  13. YAP induces cisplatin resistance through activation of autophagy in human ovarian carcinoma cells

    PubMed Central

    Xiao, Lan; Shi, Xiao-Yan; Zhang, Ying; Zhu, Ying; Zhu, Lin; Tian, Wang; Zhu, Bing-Kun; Wei, Zhao-Lian

    2016-01-01

    Objective To identify the role of YAP in cisplatin resistance in human ovarian cancer cells and in the regulation of autophagy in these cancer cells. Materials and methods The cisplatin-sensitive OV2008 parental cell line and its cisplatin-resistant variant C13K were cultured. RNA interference was used to knock down the YAP gene. Accumulation of GFP-LC3 puncta was performed by fluorescence microscopy. The formation of autophagosomes was observed by transmission electron microscopy. Drug sensitivity was examined using CCK-8 assay, while apoptosis, the level of intracellular rhodamine 123 and lysosomal acidification were analyzed by fluorescence-activated cell sorting. Acid phosphatase activity was measured using an acid phosphatase-assay kit. Real-time polymerase chain reaction, Western blotting, and immunofluorescence detection were used to detect the protein and messenger RNA expression of YAP, YAP target genes, CCND1, cleaved PARP, and caspase 3, Atg-3 and -5, and the LC3B protein. Results YAP signaling may regulate cisplatin resistance in ovarian cancer cells by augmenting cellular autophagic flux. After knockdown of YAP-sensitized C13K cells to cisplatin by inducing a decrease in autophagy, YAP led to an increase in autophagy via enhancement of autolysosome degradation. Conclusion YAP-mediated autophagy may play a protective role in cisplatin-resistant human ovarian cancer cells. Therefore, YAP-mediated autophagy should be explored as a new target for enhancing the efficacy of cisplatin against ovarian cancer and other types of malignancies. PMID:27073322

  14. High-throughput ectopic expression screen for tamoxifen resistance identifies an atypical kinase that blocks autophagy

    PubMed Central

    Gonzalez-Malerva, Laura; Park, Jaehong; Zou, Lihua; Hu, Yanhui; Moradpour, Zahra; Pearlberg, Joseph; Sawyer, Jacqueline; Stevens, Hallam; Harlow, Ed; LaBaer, Joshua

    2011-01-01

    Resistance to tamoxifen in breast cancer patients is a serious therapeutic problem and major efforts are underway to understand underlying mechanisms. Resistance can be either intrinsic or acquired. We derived a series of subcloned MCF7 cell lines that were either highly sensitive or naturally resistant to tamoxifen and studied the factors that lead to drug resistance. Gene-expression studies revealed a signature of 67 genes that differentially respond to tamoxifen in sensitive vs. resistant subclones, which also predicts disease-free survival in tamoxifen-treated patients. High-throughput cell-based screens, in which >500 human kinases were independently ectopically expressed, identified 31 kinases that conferred drug resistance on sensitive cells. One of these, HSPB8, was also in the expression signature and, by itself, predicted poor clinical outcome in one cohort of patients. Further studies revealed that HSPB8 protected MCF7 cells from tamoxifen and blocked autophagy. Moreover, silencing HSBP8 induced autophagy and caused cell death. Tamoxifen itself induced autophagy in sensitive cells but not in resistant ones, and tamoxifen-resistant cells were sensitive to the induction of autophagy by other drugs. These results may point to an important role for autophagy in the sensitivity to tamoxifen. PMID:21233418

  15. The Effect of Lactobacillus crispatus and Lactobacillus rhamnosusCulture Supernatants on Expression of Autophagy Genes and HPV E6 and E7 Oncogenes in The HeLa Cell Line

    PubMed Central

    Motevaseli, Elahe; Azam, Rosa; Akrami, Seyed Mohammad; Mazlomy, Mohammadali; Saffari, Mojtaba; Modarressi, Mohammad Hossein; Daneshvar, Maryam; Ghafouri-Fard, Soudeh

    2016-01-01

    Objective The aim of this study was to clarify the mechanism by which lactobacilli exert their cytotoxic effects on cervical cancer cells. In addition, we aimed to evalu- ate the effect of lactobacilli on the expression of human papilloma virus (HPV) onco- genes. Materials and Methods In this experimental study, using quantitative real-time polymer- ase chain reaction (PCR), we analyzed the expression of CASP3 and three autophagy genes [ATG14, BECN1 and alpha 2 catalytic subunit of AMPK (PRKAA2)] along with HPV18 E6 and E7 genes in HeLa cells before and after treatment with Lactobacillus crispatus and Lactobacillus rhamnosus culture supernatants. Results The expression of CASP3 and autophagy genes in HeLa cells was de- creased after treatment with lactobacilli culture supernatants. However, this de- crease was not significant for PRKAA2 when compared with controls. In addition, expression of HPV E6 was significantly decreased after treatment with lactobacilli culture supernatants. Conclusion Lactobacilli culture supernatants can decrease expression of ATG14 and BECN1 as well as the HPV E6 oncogene. It has been demonstrated that the main changes occurring during cervical carcinogenesis in cell machinery can be reversed by suppression of HPV oncogenes. Therefore, downregulation of HPV E6 by lacto- bacilli may have therapeutic potential for cervical cancer. As the role of autophagy in cancer is complicated, further work is required to clarify the link between downregula- tion of autophagy genes and antiproliferative effects exerted by lactobacilli. PMID:26862519

  16. Autophagy in response to photodynamic therapy: cell survival vs. cell death

    NASA Astrophysics Data System (ADS)

    Oleinick, Nancy L.; Xue, Liang-yan; Chiu, Song-mao; Joseph, Sheeba

    2009-02-01

    Autophagy (or more properly, macroautophagy) is a pathway whereby damaged organelles or other cell components are encased in a double membrane, the autophagosome, which fuses with lysosomes for digestion by lysosomal hydrolases. This process can promote cell survival by removing damaged organelles, but when damage is extensive, it can also be a mechanism of cell death. Similar to the Kessel and Agostinis laboratories, we have reported the vigorous induction of autophagy by PDT; this was found in human breast cancer MCF-7 cells whether or not they were able to efficiently induce apoptosis. One way to evaluate the role of autophagy in PDT-treated cells is to silence one of the essential genes in the pathway. Kessel and Reiners silenced the Atg7 gene of murine leukemia L1210 cells using inhibitory RNA and found sensitization to PDT-induced cell death at a low dose of PDT, implying that autophagy is protective when PDT damage is modest. We have examined the role of autophagy in an epithelium-derived cancer cell by comparing parental and Atg7-silenced MCF-7 cells to varying doses of PDT with the phthalocyanine photosensitizer Pc 4. In contrast to L1210 cells, autophagy-deficient MCF-7 cells were more resistant to the lethal effects of PDT, as judged by clonogenic assays. A possible explanation for the difference in outcome for L1210 vs. MCF-7 cells is the greatly reduced ability of the latter to undergo apoptosis, a deficiency that may convert autophagy into a cell-death process even at low PDT doses. Experiments to investigate the mechanism(s) responsible are in process.

  17. Autophagy controls carbon, nitrogen, and redox homeostasis in plants.

    PubMed

    Masclaux-Daubresse, C

    2016-05-01

    During leaf senescence, autophagy is essential for nutrient recycling and remobilization, and for plant productivity. Metabolome and transcriptome studies performed on autophagy mutants revealed major disorders in nitrogen, carbon, and redox metabolisms. Analysis showed that autophagy mutants are depleted of antioxidant anthocyanin molecules. Transcriptome analysis revealed that the depletion of anthocyanin is due to the downregulation of the master genes encoding the enzymes and regulatory proteins involved in the flavonoid pathway. The hyperaccumulation of salicylic acid and the depletion of anthocyanin in autophagy mutants might result from the rerouting of carbon resources in the phenylpropanoid pathway and amplify oxidative stress in autophagy mutants. PMID:25484096

  18. Autophagy in cancer

    PubMed Central

    Zhi, Xiaoyong

    2015-01-01

    Autophagy is a catabolic degradation process in which cellular proteins and organelles are engulfed by double-membrane autophagosomes and degraded in lysosomes. Autophagy has emerged as a critical pathway in tumor development and cancer therapy, although its precise function remains a conundrum. The current consensus is that autophagy has a dual role in cancer. On the one hand, autophagy functions as a tumor suppressor mechanism by preventing the accumulation of damaged organelles and aggregated proteins. On the other hand, autophagy is a key cell survival mechanism for established tumors; therefore autophagy inhibition suppresses tumor progression. Here, we summarize recent progress on the role of autophagy in tumorigenesis and cancer therapy. PMID:25750736

  19. Liver autophagy in anorexia nervosa and acute liver injury.

    PubMed

    Kheloufi, Marouane; Boulanger, Chantal M; Durand, François; Rautou, Pierre-Emmanuel

    2014-01-01

    Autophagy, a lysosomal catabolic pathway for long-lived proteins and damaged organelles, is crucial for cell homeostasis, and survival under stressful conditions. During starvation, autophagy is induced in numerous organisms ranging from yeast to mammals, and promotes survival by supplying nutrients and energy. In the early neonatal period, when transplacental nutrients supply is interrupted, starvation-induced autophagy is crucial for neonates' survival. In adult animals, autophagy provides amino acids and participates in glucose metabolism following starvation. In patients with anorexia nervosa, autophagy appears initially protective, allowing cells to copes with nutrient deprivation. However, when starvation is critically prolonged and when body mass index reaches 13 kg/m(2) or lower, acute liver insufficiency occurs with features of autophagic cell death, which can be observed by electron microscopy analysis of liver biopsy samples. In acetaminophen overdose, a classic cause of severe liver injury, autophagy is induced as a protective mechanism. Pharmacological enhancement of autophagy protects against acetaminophen-induced necrosis. Autophagy is also activated as a rescue mechanism in response to Efavirenz-induced mitochondrial dysfunction. However, Efavirenz overdose blocks autophagy leading to liver cell death. In conclusion, in acute liver injury, autophagy appears as a protective mechanism that can be however blocked or overwhelmed. PMID:25250330

  20. Liver Autophagy in Anorexia Nervosa and Acute Liver Injury

    PubMed Central

    Kheloufi, Marouane; Boulanger, Chantal M.; Durand, François

    2014-01-01

    Autophagy, a lysosomal catabolic pathway for long-lived proteins and damaged organelles, is crucial for cell homeostasis, and survival under stressful conditions. During starvation, autophagy is induced in numerous organisms ranging from yeast to mammals, and promotes survival by supplying nutrients and energy. In the early neonatal period, when transplacental nutrients supply is interrupted, starvation-induced autophagy is crucial for neonates' survival. In adult animals, autophagy provides amino acids and participates in glucose metabolism following starvation. In patients with anorexia nervosa, autophagy appears initially protective, allowing cells to copes with nutrient deprivation. However, when starvation is critically prolonged and when body mass index reaches 13 kg/m2 or lower, acute liver insufficiency occurs with features of autophagic cell death, which can be observed by electron microscopy analysis of liver biopsy samples. In acetaminophen overdose, a classic cause of severe liver injury, autophagy is induced as a protective mechanism. Pharmacological enhancement of autophagy protects against acetaminophen-induced necrosis. Autophagy is also activated as a rescue mechanism in response to Efavirenz-induced mitochondrial dysfunction. However, Efavirenz overdose blocks autophagy leading to liver cell death. In conclusion, in acute liver injury, autophagy appears as a protective mechanism that can be however blocked or overwhelmed. PMID:25250330

  1. Ketogenic diet change cPLA2/clusterin and autophagy related gene expression and correlate with cognitive deficits and hippocampal MFs sprouting following neonatal seizures.

    PubMed

    Ni, Hong; Zhao, Dong-Jing; Tian, Tian

    2016-02-01

    Because the ketogenic diet (KD) was affecting expression of energy metabolism- related genes in hippocampus and because lipid membrane peroxidation and its associated autophagy stress were also found to be involved in energy depletion, we hypothesized that KD might exert its neuroprotective action via lipid membrane peroxidation and autophagic signaling. Here, we tested this hypothesis by examining the long-term expression of lipid membrane peroxidation-related cPLA2 and clusterin, its downstream autophagy marker Beclin-1, LC3 and p62, as well as its execution molecule Cathepsin-E following neonatal seizures and chronic KD treatment. On postnatal day 9 (P9), 48 Sprague-Dawley rats were randomly assigned to two groups: flurothyl-induced recurrent seizures group and control group. On P28, they were further randomly divided into the seizure group without ketogenic diet (RS+ND), seizure plus ketogenic diet (RS+KD), the control group without ketogenic diet (NS+ND), and the control plus ketogenic diet (NS+KD). Morris water maze test was performed during P37-P43. Then mossy fiber sprouting and the protein levels were detected by Timm staining and Western blot analysis, respectively. Flurothyl-induced RS+ND rats show a long-term lower amount of cPLA2 and LC3II/I, and higher amount of clusterin, Beclin-1, p62 and Cathepsin-E which are in parallel with hippocampal mossy fiber sprouting and cognitive deficits. Furthermore, chronic KD treatment (RS+KD) is effective in restoring these molecular, neuropathological and cognitive changes. The results imply that a lipid membrane peroxidation and autophagy-associated pathway is involved in the aberrant hippocampal mossy fiber sprouting and cognitive deficits following neonatal seizures, which might be a potential target of KD for the treatment of neonatal seizure-induced brain damage. PMID:26709877

  2. Identifying and characterizing barley genes that protect against trichothecenes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our overall goal is to identify genes that play a role in resistance to Fusarium Head Blight (FHB) and to develop and test transgenic wheat carrying these genes. In particular, we are interested in identifying genes that protect barley and wheat from the effects of trichothecenes. Previously, we con...

  3. Effect of 1,25-dihydroxyvitamin D3 on the expression of mannose receptor, DC-SIGN and autophagy genes in pulmonary tuberculosis.

    PubMed

    Afsal, K; Selvaraj, P

    2016-07-01

    1,25-dihydroxyvitamin D3 [1,25(OH)2D3] is a powerful immuno-modulator, which enhances expression of antimicrobial peptides and induces autophagy in monocytes/macrophages. Since 1,25(OH)2D3 increases the phagocytic potential of monocytes/macrophages, we have explored the effect of 1,25(OH)2D3 on the expression of receptors such as mannose receptor (CD206) and DC-SIGN (CD209) as well as autophagy genes such as ATG5 and Beclin-1 (BECN1) in monocytes/macrophages of healthy controls (HCs) and pulmonary tuberculosis (PTB) patients with and without cavitary disease. Peripheral blood mononuclear cells (PBMCs) were isolated from 40 HCs and 40 PTB patients and were cultured for 72 h with Mtb in the presence or absence of 1,25(OH)2D3 at 10(-7) M concentration. 1,25(OH)2D3 significantly upregulated the expression of mannose receptor, ATG5 and BECN1; whereas DC-SIGN expression was suppressed in Mtb infected cells of both study groups (p < 0.05). The 1,25(OH)2D3-induced expression of CD206, ATG5 and BECN1 genes was lower in PTB patients compared to HCs, whereas expression of these genes was impaired in PTB patients with cavitary disease. Moreover, the relative expression of ATG5 and BECN1 was positively correlated with monocyte/macrophage phagocytosis and cathelicidin antimicrobial peptide gene expression in HCs and PTB patients (p < 0.05). Our study results suggest that vitamin D supplementation in PTB patients without cavitary disease could enhance innate immune functions and may help to control intracellular growth of mycobacteria in macrophages. PMID:27449998

  4. Regulation of inflammasomes by autophagy.

    PubMed

    Saitoh, Tatsuya; Akira, Shizuo

    2016-07-01

    Inflammasomes detect pathogen-associated molecular patterns to induce inflammatory innate immune responses and play a key role in host defense against infectious agents. However, inflammasomes are often wrongly activated by metabolites, amyloids, and environmental irritants. This induces massive inflammation, causing severe tissue damage, and results in the development of inflammatory diseases. Hence cellular machineries regulating both "activation" and "inactivation" of inflammasomes are definitely important. Recent studies have shown that autophagy, an intracellular degradation system associated with maintenance of cellular homeostasis, plays a key role in inflammasome inactivation. Notably, autophagy deficiency caused by gene mutation disrupts organelle elimination and thus induces aberrant activation of inflammasomes, leading to severe tissue damage. Here we review recent findings regarding the involvement of autophagy in the regulation of inflammasome activation and development of inflammatory disorders. PMID:27373323

  5. The metastasis suppressor, N-myc downstream-regulated gene 1 (NDRG1), inhibits stress-induced autophagy in cancer cells.

    PubMed

    Sahni, Sumit; Bae, Dong-Hun; Lane, Darius J R; Kovacevic, Zaklina; Kalinowski, Danuta S; Jansson, Patric J; Richardson, Des R

    2014-04-01

    N-myc downstream regulated gene 1 (NDRG1) is a potent metastasis suppressor with an undefined role in the stress response. Autophagy is a pro-survival pathway and can be regulated via the protein kinase-like endoplasmic reticulum kinase (PERK)/eIF2α-mediated endoplasmic reticulum (ER) stress pathway. Hence, we investigated the role of NDRG1 in stress-induced autophagy as a mechanism of inhibiting metastasis via the induction of apoptosis. As thiosemicarbazone chelators induce stress and up-regulate NDRG1 to inhibit metastasis, we studied their effects on the ER stress response and autophagy. This was important to assess, as little is understood regarding the role of the stress induced by iron depletion and its role in autophagy. We observed that the chelator, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), which forms redox-active iron and copper complexes, effectively induced ER stress as shown by activation of the PERK/eIF2α pathway. Dp44mT also increased the expression of the autophagic marker, LC3-II, and this was dependent on activation of the PERK/eIF2α axis, as silencing PERK prevented LC3-II accumulation. The effect of Dp44mT on LC3-II expression was at least partially due to iron-depletion, as this effect was also demonstrated with the classical iron chelator, desferrioxamine (DFO), and was not observed for the DFO-iron complex. NDRG1 overexpression also inhibited basal autophagic initiation and the ER stress-mediated autophagic pathway via suppression of the PERK/eIF2α axis. Moreover, NDRG1-mediated suppression of the pro-survival autophagic pathway probably plays a role in its anti-metastatic effects by inducing apoptosis. In fact, multiple pro-apoptotic markers were increased, whereas anti-apoptotic Bcl-2 was decreased upon NDRG1 overexpression. This study demonstrates the role of NDRG1 as an autophagic inhibitor that is important for understanding its mechanism of action. PMID:24532803

  6. Roles of Autophagy and Autophagy-Related Proteins in Antifungal Immunity

    PubMed Central

    Kanayama, Masashi; Shinohara, Mari L.

    2016-01-01

    Autophagy was initially characterized as a process to digest cellular components, including damaged cell organelles or unused proteins. However, later studies showed that autophagy plays an important role to protect hosts from microbial infections. Accumulating evidences showed the contribution of autophagy itself and autophagy-related proteins (ATGs) in the clearance of bacteria, virus, and parasites. A number of studies also revealed the molecular mechanisms by which autophagy is initiated and developed. Furthermore, it is now understood that some ATGs are shared between two distinct processes; autophagy and LC3-associated phagocytosis (LAP). Thus, our understanding on autophagy has been greatly enhanced in the last decade. By contrast, roles of autophagy and ATGs in fungal infections are still elusive relative to those in bacterial and viral infections. Based on limited numbers of reports, ATG-mediated host responses appear to significantly vary depending on invading fungal species. In this review, we discuss how autophagy and ATGs are involved in antifungal immune responses based on recent discoveries. PMID:26925060

  7. Autophagy: A double-edged sword in intervertebral disk degeneration.

    PubMed

    Zhang, Shu-Jun; Yang, Wei; Wang, Cheng; He, Wen-Si; Deng, Hai-Yang; Yan, Yi-Guo; Zhang, Jian; Xiang, Yong-Xiao; Wang, Wen-Jun

    2016-06-01

    Autophagy is a homeostatic mechanism through which intracellular damaged organelles and proteins are degraded and recycled in response to increased metabolic demands or stresses. Although primarily cytoprotective, dysfunction of autophagy is often associated with many degenerative diseases, including intervertebral disc (IVD) degeneration (IDD). As a main contributing factor to low back pain, IDD is the pathological basis for various debilitating spinal diseases. Either higher or lower levels of autophagy are observed in degenerative IVD cells. Despite the precise role of autophagy in disc degeneration that is still controversial, with difference from protection to aggravation, targeting autophagy has shown promise for mitigating disc degeneration. In the current review, we summarize the changes of autophagy in degenerative IVD cells and mainly discuss the relationship between autophagy and IDD. With continued efforts, modulation of the autophagic process could be a potential and attractive therapeutic strategy for degenerative disc disease. PMID:27018178

  8. Therapeutic targeting of autophagy in neurodegenerative and infectious diseases

    PubMed Central

    Bento, Carla F.

    2015-01-01

    Autophagy is a conserved process that uses double-membrane vesicles to deliver cytoplasmic contents to lysosomes for degradation. Although autophagy may impact many facets of human biology and disease, in this review we focus on the ability of autophagy to protect against certain neurodegenerative and infectious diseases. Autophagy enhances the clearance of toxic, cytoplasmic, aggregate-prone proteins and infectious agents. The beneficial roles of autophagy can now be extended to supporting cell survival and regulating inflammation. Autophagic control of inflammation is one area where autophagy may have similar benefits for both infectious and neurodegenerative diseases beyond direct removal of the pathogenic agents. Preclinical data supporting the potential therapeutic utility of autophagy modulation in such conditions is accumulating. PMID:26101267

  9. Dihydroptychantol A, a macrocyclic bisbibenzyl derivative, induces autophagy and following apoptosis associated with p53 pathway in human osteosarcoma U2OS cells

    SciTech Connect

    Li Xia; Wu, William K.K.; Sun Bin; Cui Min; Liu Shanshan; Gao Jian; Lou Hongxiang

    2011-03-01

    Dihydroptychantol A (DHA), a novel macrocyclic bisbibenzyl compound extracted from liverwort Asterella angusta, has antifungal and multi-drug resistance reversal properties. Here, the chemically synthesized DHA was employed to test its anti-cancer activities in human osteosarcoma U2OS cells. Our results demonstrated that DHA induced autophagy followed by apoptotic cell death accompanied with G{sub 2}/M-phase cell cycle arrest in U2OS cells. DHA-induced autophagy was morphologically characterized by the formation of double membrane-bound autophagic vacuoles recognizable at the ultrastructural level. DHA also increased the levels of LC3-II, a marker of autophagy. Surprisingly, DHA-mediated apoptotic cell death was potentiated by the autophagy inhibitor 3-methyladenine, suggesting that autophagy may play a protective role that impedes the eventual cell death. Furthermore, p53 was shown to be involved in DHA-meditated autophagy and apoptosis. In this connection, DHA increased nuclear expression of p53, induced p53 phosphorylation, and upregulated p53 target gene p21{sup Waf1/Cip1}. In contrast, cytoplasmic p53 was reduced by DHA, which contributed to the stimulation of autophagy. In relation to the cell cycle, DHA decreased the expression of cyclin B{sub 1}, a cyclin required for progression through the G{sub 2}/M phase. Taken together, DHA induces G{sub 2}/M-phase cell cycle arrest and apoptosis in U2OS cells. DHA-induced apoptosis was preceded by the induction of protective autophagy. DHA-mediated autophagy and apoptosis are associated with the cytoplasmic and nuclear functions of p53.

  10. Autophagy in lung disease pathogenesis and therapeutics

    PubMed Central

    Ryter, Stefan W.; Choi, Augustine M.K.

    2015-01-01

    Autophagy, a cellular pathway for the degradation of damaged organelles and proteins, has gained increasing importance in human pulmonary diseases, both as a modulator of pathogenesis and as a potential therapeutic target. In this pathway, cytosolic cargos are sequestered into autophagosomes, which are delivered to the lysosomes where they are enzymatically degraded and then recycled as metabolic precursors. Autophagy exerts an important effector function in the regulation of inflammation, and immune system functions. Selective pathways for autophagic degradation of cargoes may have variable significance in disease pathogenesis. Among these, the autophagic clearance of bacteria (xenophagy) may represent a crucial host defense mechanism in the pathogenesis of sepsis and inflammatory diseases. Our recent studies indicate that the autophagic clearance of mitochondria, a potentially protective program, may aggravate the pathogenesis of chronic obstructive pulmonary disease by activating cell death programs. We report similar findings with respect to the autophagic clearance of cilia components, which can contribute to airways dysfunction in chronic lung disease. In certain diseases such as pulmonary hypertension, autophagy may confer protection by modulating proliferation and cell death. In other disorders, such as idiopathic pulmonary fibrosis and cystic fibrosis, impaired autophagy may contribute to pathogenesis. In lung cancer, autophagy has multiple consequences by limiting carcinogenesis, modulating therapeutic effectiveness, and promoting tumor cell survival. In this review we highlight the multiple functions of autophagy and its selective autophagy subtypes that may be of significance to the pathogenesis of human disease, with an emphasis on lung disease and therapeutics. PMID:25617802

  11. Endothelial nitric-oxide synthase antisense (NOS3AS) gene encodes an autophagy-related protein (APG9-like2) highly expressed in trophoblast.

    PubMed

    Yamada, Takahiro; Carson, Andrew R; Caniggia, Isabella; Umebayashi, Kyohei; Yoshimori, Tamotsu; Nakabayashi, Kazuhiko; Scherer, Stephen W

    2005-05-01

    Macroautophagy is an intracellular degradation system for the majority of proteins and some organelles that is conserved in all eukaryotic species. The precise role of autophagy in mammalian development and potential involvement in disease remain to be discerned. Yeast Atg9p is the first integral membrane protein shown to be essential for the cytoplasm to vacuole targeting (Cvt) pathway and autophagy, whereas its mammalian functional orthologue has yet to be identified. We have identified two human genes homologous to yeast Atg9p and designated these as APG9L1 and APG9L2. We have previously identified APG9L2 as NOS3AS, which participates in the post-transcriptional regulation of the endothelial nitric-oxide synthase (NOS3) gene on chromosome 7 through its antisense overlap. In human adult tissues, APG9L1 was ubiquitously expressed, whereas APG9L2 was highly expressed in placenta (trophoblast cells) and pituitary gland. In transient transfection assays we found that both proteins were primarily localized to the perinuclear region and also scattered throughout the cytosol as dots, a subset of which colocalized with an autophagosome-specific marker LC3 under starvation conditions. Finally, by the small interfering RNA-mediated knockdown of APG9L1 in HeLa cells, we demonstrated that APG9L1 is essential for starvation-induced autophagosome formation. In addition, APG9L2 can functionally complement APG9L1 in this process. These results, taken together with those of phylogenetic and sequence analyses, suggest that both APG9L1 and APG9L2 are functionally orthologous to the yATG9 in autophagosome formation. Moreover, APG9L2 is a vertebrate-specific gene that may have gained critical roles in mammalian-specific developmental events, such as placentation, through rapid evolution. PMID:15755735

  12. Autophagy-related prognostic signature for breast cancer.

    PubMed

    Gu, Yunyan; Li, Pengfei; Peng, Fuduan; Zhang, Mengmeng; Zhang, Yuanyuan; Liang, Haihai; Zhao, Wenyuan; Qi, Lishuang; Wang, Hongwei; Wang, Chenguang; Guo, Zheng

    2016-03-01

    Autophagy is a process that degrades intracellular constituents, such as long-lived or damaged proteins and organelles, to buffer metabolic stress under starvation conditions. Deregulation of autophagy is involved in the progression of cancer. However, the predictive value of autophagy for breast cancer prognosis remains unclear. First, based on gene expression profiling, we found that autophagy genes were implicated in breast cancer. Then, using the Cox proportional hazard regression model, we detected autophagy prognostic signature for breast cancer in a training dataset. We identified a set of eight autophagy genes (BCL2, BIRC5, EIF4EBP1, ERO1L, FOS, GAPDH, ITPR1 and VEGFA) that were significantly associated with overall survival in breast cancer. The eight autophagy genes were assigned as a autophagy-related prognostic signature for breast cancer. Based on the autophagy-related signature, the training dataset GSE21653 could be classified into high-risk and low-risk subgroups with significantly different survival times (HR = 2.72, 95% CI = (1.91, 3.87); P = 1.37 × 10(-5)). Inactivation of autophagy was associated with shortened survival of breast cancer patients. The prognostic value of the autophagy-related signature was confirmed in the testing dataset GSE3494 (HR = 2.12, 95% CI = (1.48, 3.03); P = 1.65 × 10(-3)) and GSE7390 (HR = 1.76, 95% CI = (1.22, 2.54); P = 9.95 × 10(-4)). Further analysis revealed that the prognostic value of the autophagy signature was independent of known clinical prognostic factors, including age, tumor size, grade, estrogen receptor status, progesterone receptor status, ERBB2 status, lymph node status and TP53 mutation status. Finally, we demonstrated that the autophagy signature could also predict distant metastasis-free survival for breast cancer. PMID:25620657

  13. Autophagy promotes resistance to photodynamic therapy-induced apoptosis selectively in colorectal cancer stem-like cells

    PubMed Central

    Wei, Ming-Feng; Chen, Min-Wei; Chen, Ke-Cheng; Lou, Pei-Jen; Lin, Susan Yun-Fan; Hung, Shih-Chieh; Hsiao, Michael; Yao, Cheng-Jung; Shieh, Ming-Jium

    2014-01-01

    Recent studies have indicated that cancer stem-like cells (CSCs) exhibit a high resistance to current therapeutic strategies, including photodynamic therapy (PDT), leading to the recurrence and progression of colorectal cancer (CRC). In cancer, autophagy acts as both a tumor suppressor and a tumor promoter. However, the role of autophagy in the resistance of CSCs to PDT has not been reported. In this study, CSCs were isolated from colorectal cancer cells using PROM1/CD133 (prominin 1) expression, which is a surface marker commonly found on stem cells of various tissues. We demonstrated that PpIX-mediated PDT induced the formation of autophagosomes in PROM1/CD133+ cells, accompanied by the upregulation of autophagy-related proteins ATG3, ATG5, ATG7, and ATG12. The inhibition of PDT-induced autophagy by pharmacological inhibitors and silencing of the ATG5 gene substantially triggered apoptosis of PROM1/CD133+ cells and decreased the ability of colonosphere formation in vitro and tumorigenicity in vivo. In conclusion, our results revealed a protective role played by autophagy against PDT in CSCs and indicated that targeting autophagy could be used to elevate the PDT sensitivity of CSCs. These findings would aid in the development of novel therapeutic approaches for CSC treatment. PMID:24905352

  14. Autophagy and apoptosis are redundantly required for C. elegans embryogenesis.

    PubMed

    Borsos, Eva; Erdélyi, Péter; Vellai, Tibor

    2011-05-01

    Apoptosis, the main form of regulated (or programmed) cell death, allows the organism to tightly control cell numbers and tissue size, and to protect itself from potentially damaging cells. This type of cellular self-killing has long been assumed to be essential for early development. In the nematode Caenorhabditis elegans, however, the core apoptotic cell death pathway appears to be dispensable for embryogenesis when most developmental cell deaths take place: mutant nematodes defective for apoptosis develop into adulthood, with superficially normal morphology and behavior. Accumulating evidence indicates a similar situation in mammalian systems as well. For example, apoptosis-deficient mice can grow as healthy, fertile adults. These observations raise the possibility that alternative cell death mechanisms may compensate for the lack of apoptotic machinery in developing embryos. Interestingly, C. elegans embryogenesis can also occur without autophagy, an alternative form of cellular self-destruction (also called autophagic cell death). In an upcoming paper we report that simultaneous inactivation of the autophagic and apoptotic gene cascades in C. elegans arrests development at early stages, and the affected embryos exhibit severe morphological defects. Double-mutant nematode embryos deficient in both autophagy and apoptosis are unable to undergo body elongation or to arrange several tissues correctly. This novel function of autophagy genes in morphogenesis indicates a more fundamental role for cellular self-digestion in tissue patterning than previously thought. PMID:21285529

  15. Essential role for the ATG4B protease and autophagy in bleomycin-induced pulmonary fibrosis.

    PubMed

    Cabrera, Sandra; Maciel, Mariana; Herrera, Iliana; Nava, Teresa; Vergara, Fabián; Gaxiola, Miguel; López-Otín, Carlos; Selman, Moisés; Pardo, Annie

    2015-04-01

    Autophagy is a critical cellular homeostatic process that controls the turnover of damaged organelles and proteins. Impaired autophagic activity is involved in a number of diseases, including idiopathic pulmonary fibrosis suggesting that altered autophagy may contribute to fibrogenesis. However, the specific role of autophagy in lung fibrosis is still undefined. In this study, we show for the first time, how autophagy disruption contributes to bleomycin-induced lung fibrosis in vivo using an Atg4b-deficient mouse as a model. Atg4b-deficient mice displayed a significantly higher inflammatory response at 7 d after bleomycin treatment associated with increased neutrophilic infiltration and significant alterations in proinflammatory cytokines. Likewise, we found that Atg4b disruption resulted in augmented apoptosis affecting predominantly alveolar and bronchiolar epithelial cells. At 28 d post-bleomycin instillation Atg4b-deficient mice exhibited more extensive and severe fibrosis with increased collagen accumulation and deregulated extracellular matrix-related gene expression. Together, our findings indicate that the ATG4B protease and autophagy play a crucial role protecting epithelial cells against bleomycin-induced stress and apoptosis, and in the regulation of the inflammatory and fibrotic responses. PMID:25906080

  16. SIRT1 inactivation induces inflammation through the dysregulation of autophagy in human THP-1 cells

    SciTech Connect

    Takeda-Watanabe, Ai; Kitada, Munehiro; Kanasaki, Keizo; Koya, Daisuke

    2012-10-12

    Highlights: Black-Right-Pointing-Pointer SIRT1 inactivation decreases autophagy in THP-1 cell. Black-Right-Pointing-Pointer Inhibition of autophagy induces inflammation. Black-Right-Pointing-Pointer SIRT1 inactivation induces inflammation through NF-{kappa}B activation. Black-Right-Pointing-Pointer The p62/Sqstm1 accumulation by impairment of autophagy is related to NF-{kappa}B activation. Black-Right-Pointing-Pointer SIRT1 inactivation is involved in the activation of mTOR and decreased AMPK activation. -- Abstract: Inflammation plays a crucial role in atherosclerosis. Monocytes/macrophages are some of the cells involved in the inflammatory process in atherogenesis. Autophagy exerts a protective effect against cellular stresses like inflammation, and it is regulated by nutrient-sensing pathways. The nutrient-sensing pathway includes SIRT1, a NAD{sup +}-dependent histone deacetylase, which is implicated in the regulation of a variety of cellular processes including inflammation and autophagy. The mechanism through which the dysfunction of SIRT1 contributes to the regulation of inflammation in relation to autophagy in monocytes/macrophages is unclear. In the present study, we demonstrate that treatment with 2-[(2-Hydroxynaphthalen-1-ylmethylene)amino]-N-(1-phenethyl)benzamide (Sirtinol), a chemical inhibitor of SIRT1, induces the overexpression of inflammation-related genes such as tumor necrosis factor (TNF)-{alpha} and interleukin (IL)-6 through nuclear factor (NF)-{kappa}B signaling activation, which is associated with autophagy dysfunction, as shown through p62/Sqstm1 accumulation and decreased expression of light chain (LC) 3 II in THP-1 cells. The autophagy inhibitor, 3-methyladenine, also induces inflammation-related NF-{kappa}B activation. In p62/Sqstm1 knockdown cells, Sirtinol-induced inflammation through NF-{kappa}B activation is blocked. In addition, inhibition of SIRT1 is involved in the activation of the mammalian target of rapamycin (mTOR) pathway and

  17. Tyrosinase-Cre-Mediated Deletion of the Autophagy Gene Atg7 Leads to Accumulation of the RPE65 Variant M450 in the Retinal Pigment Epithelium of C57BL/6 Mice

    PubMed Central

    Sukseree, Supawadee; Chen, Ying-Ting; Laggner, Maria; Gruber, Florian; Petit, Valérie; Nagelreiter, Ionela-Mariana; Mlitz, Veronika; Rossiter, Heidemarie; Pollreisz, Andreas; Schmidt-Erfurth, Ursula; Larue, Lionel; Tschachler, Erwin

    2016-01-01

    Targeted gene knockout mouse models have helped to identify roles of autophagy in many tissues. Here, we investigated the retinal pigment epithelium (RPE) of Atg7f/f Tyr-Cre mice (on a C57BL/6 background), in which Cre recombinase is expressed under the control of the tyrosinase promoter to delete the autophagy gene Atg7. In line with pigment cell-directed blockade of autophagy, the RPE and the melanocytes of the choroid showed strong accumulation of the autophagy adaptor and substrate, sequestosome 1 (Sqstm1)/p62, relative to the levels in control mice. Immunofluorescence and Western blot analysis demonstrated that the RPE, but not the choroid melanocytes, of Atg7f/f Tyr-Cre mice also had strongly increased levels of retinoid isomerohydrolase RPE65, a pivotal enzyme for the maintenance of visual perception. In contrast to Sqstm1, genes involved in retinal regeneration, i.e. Lrat, Rdh5, Rgr, and Rpe65, were expressed at higher mRNA levels. Sequencing of the Rpe65 gene showed that Atg7f/f and Atg7f/f Tyr-Cre mice carry a point mutation (L450M) that is characteristic for the C57BL/6 mouse strain and reportedly causes enhanced degradation of the RPE65 protein by an as-yet unknown mechanism. These results suggest that the increased abundance of RPE65 M450 in the RPE of Atg7f/f Tyr-Cre mice is, at least partly, mediated by upregulation of Rpe65 transcription; however, our data are also compatible with the hypothesis that the RPE65 M450 protein is degraded by Atg7-dependent autophagy in Atg7f/f mice. Further studies in mice of different genetic backgrounds are necessary to determine the relative contributions of these mechanisms. PMID:27537685

  18. Protective Effects of Astaxanthin on ConA-Induced Autoimmune Hepatitis by the JNK/p-JNK Pathway-Mediated Inhibition of Autophagy and Apoptosis

    PubMed Central

    Liu, Tong; Wang, Junshan; Dai, Weiqi; Wang, Fan; Zheng, Yuanyuan; Chen, Kan; Li, Sainan; Abudumijiti, Huerxidan; Zhou, Zheng; Wang, Jianrong; Lu, Wenxia; Zhu, Rong; Yang, Jing; Zhang, Huawei; Yin, Qin; Wang, Chengfen; Zhou, Yuqing; Lu, Jie; Zhou, Yingqun; Guo, Chuanyong

    2015-01-01

    Objective Astaxanthin, a potent antioxidant, exhibits a wide range of biological activities, including antioxidant, atherosclerosis and antitumor activities. However, its effect on concanavalin A (ConA)-induced autoimmune hepatitis remains unclear. The aim of this study was to investigate the protective effects of astaxanthin on ConA-induced hepatitis in mice, and to elucidate the mechanisms of regulation. Materials and Methods Autoimmune hepatitis was induced in in Balb/C mice using ConA (25 mg/kg), and astaxanthin was orally administered daily at two doses (20 mg/kg and 40 mg/kg) for 14 days before ConA injection. Levels of serum liver enzymes and the histopathology of inflammatory cytokines and other maker proteins were determined at three time points (2, 8 and 24 h). Primary hepatocytes were pretreated with astaxanthin (80 μM) in vitro 24 h before stimulation with TNF-α (10 ng/ml). The apoptosis rate and related protein expression were determined 24 h after the administration of TNF-α. Results Astaxanthin attenuated serum liver enzymes and pathological damage by reducing the release of inflammatory factors. It performed anti-apoptotic effects via the descending phosphorylation of Bcl-2 through the down-regulation of the JNK/p-JNK pathway. Conclusion This research firstly expounded that astaxanthin reduced immune liver injury in ConA-induced autoimmune hepatitis. The mode of action appears to be downregulation of JNK/p-JNK-mediated apoptosis and autophagy. PMID:25761053

  19. Autophagy, Metabolism, and Cancer.

    PubMed

    White, Eileen; Mehnert, Janice M; Chan, Chang S

    2015-11-15

    Macroautophagy (autophagy hereafter) captures intracellular proteins and organelles and degrades them in lysosomes. The degradation breakdown products are released from lysosomes and recycled into metabolic and biosynthetic pathways. Basal autophagy provides protein and organelle quality control by eliminating damaged cellular components. Starvation-induced autophagy recycles intracellular components into metabolic pathways to sustain mitochondrial metabolic function and energy homeostasis. Recycling by autophagy is essential for yeast and mammals to survive starvation through intracellular nutrient scavenging. Autophagy suppresses degenerative diseases and has a context-dependent role in cancer. In some models, cancer initiation is suppressed by autophagy. By preventing the toxic accumulation of damaged protein and organelles, particularly mitochondria, autophagy limits oxidative stress, chronic tissue damage, and oncogenic signaling, which suppresses cancer initiation. This suggests a role for autophagy stimulation in cancer prevention, although the role of autophagy in the suppression of human cancer is unclear. In contrast, some cancers induce autophagy and are dependent on autophagy for survival. Much in the way that autophagy promotes survival in starvation, cancers can use autophagy-mediated recycling to maintain mitochondrial function and energy homeostasis to meet the elevated metabolic demand of growth and proliferation. Thus, autophagy inhibition may be beneficial for cancer therapy. Moreover, tumors are more autophagy-dependent than normal tissues, suggesting that there is a therapeutic window. Despite these insights, many important unanswered questions remain about the exact mechanisms of autophagy-mediated cancer suppression and promotion, how relevant these observations are to humans, and whether the autophagy pathway can be modulated therapeutically in cancer. See all articles in this CCR Focus section, "Cell Death and Cancer Therapy." PMID:26567363

  20. Autophagy: New Questions from Recent Answers

    PubMed Central

    2012-01-01

    Macroautophagy (hereafter autophagy) is currently one of the areas of medical life sciences attracting a great interest because of its pathological implications and therapy potentials. The discovery of the autophagy-related genes (ATGs) has been the key event in this research field because their study has led to the acquisition of new knowledge about the mechanism of this transport pathway. In addition, the investigation of these genes in numerous model systems has revealed the central role that autophagy plays in maintaining the cell homeostasis. This process carries out numerous physiological functions, some of which were unpredicted and thus surprising. Here, we will review some of the questions about the mechanism and function of autophagy that still remain unanswered, and new ones that have emerged from the recent discoveries.

  1. Autophagy: a decisive process for stemness

    PubMed Central

    García-Prat, Laura

    2016-01-01

    Mature skeletal muscle is a stable tissue imposing low homeostatic demand on its stem cells, which remain in a quiescent state in their niche over time. We have shown that these long-lived resting stem cells attenuate proteotoxicity and avoid senescence through basal autophagy. This protective “clean-up” system is lost during aging, resulting in stem cell regenerative decline. Thus, autophagy is required for muscle stem cell homeostasis maintenance. PMID:26934325

  2. Estrogen receptor beta (ERβ) produces autophagy and necroptosis in human seminoma cell line through the binding of the Sp1 on the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) promoter gene.

    PubMed

    Guido, Carmela; Panza, Salvatore; Santoro, Marta; Avena, Paola; Panno, Maria Luisa; Perrotta, Ida; Giordano, Francesca; Casaburi, Ivan; Catalano, Stefania; De Amicis, Francesca; Sotgia, Federica; Lisanti, Michael P; Andò, Sebastiano; Aquila, Saveria

    2012-08-01

    Testicular germ cell tumors are the most common tumor in male and the least studied. We focused on human seminoma using the TCAM2 cell line. Through ERβ, 10 nM estradiol (E2) was able to induce PTEN gene expression and promoter transactivation. Transient transfections, ChIP and EMSA assays evidenced the 5'-flanking region of PTEN gene promoter E2-responsive. The ERβ binding to the Sp1 on PTEN promoter decreased cell survival. The presence of ERβ or PTEN is necessary to induce the loss of cell survival upon E2, addressing their cooperation in this action. pAKT and AKT expression decreased under E2 and DPN, while known apoptotic markers appeared to be unchanged. The PI3K/AKT pathway inhibition also leads to autophagy: E2 and DPN enhanced the expression of autophagy-related markers such as PI3III, Beclin 1, AMBRA and UVRAG. MDC and TEM assays confirmed E2-induced autophagy. The absence of DNA fragmentation, caspase 9 and PARP1 cleavages suggested that necroptosis and/or parthanatos may occur. FACS analysis, LDH assay and RIP1 expression attested this hypothesis. Our study reveals a unique mechanism through which ERβ/PTEN signaling induces cell death in TCAM2 by autophagy and necroptosis. These data, supporting estrogen-dependency of human seminoma, propose ERβ ligands for therapeutic use in the treatment of this pathological condition. PMID:22810004

  3. Eaten alive: novel insights into autophagy from multicellular model systems

    PubMed Central

    Zhang, Hong; Baehrecke, Eric H.

    2015-01-01

    Autophagy delivers cytoplasmic material to lysosomes for degradation. First identified in yeast, the core genes that control this process are conserved in higher organisms. Studies of mammalian cell cultures have expanded our understanding of the core autophagy pathway, but cannot reveal the unique animal-specific mechanisms for the regulation and function of autophagy. Multicellular organisms have different types of cells that possess distinct composition, morphology, and organization of intracellular organelles. In addition, the autophagic machinery integrates signals from other cells and environmental conditions to maintain cell, tissue and organism homeostasis. Here, we highlight how studies of autophagy in flies and worms have identified novel core autophagy genes and mechanisms, and provided insight into the context-specific regulation and function of autophagy. PMID:25862458

  4. Overexpression of the autophagy-related gene SiATG8a from foxtail millet (Setaria italica L.) confers tolerance to both nitrogen starvation and drought stress in Arabidopsis.

    PubMed

    Li, Wei-wei; Chen, Ming; Zhong, Li; Liu, Jia-ming; Xu, Zhao-shi; Li, Lian-cheng; Zhou, Yong-Bin; Guo, Chang-Hong; Ma, You-Zhi

    2015-12-25

    Autophagy is an evolutionarily conserved biological process in all eukaryotes for the degradation of intracellular components for nutrient recycling. Autophagy is known to be involved in responses to low nitrogen stress in Arabidopsis. Foxtail millet has strong abiotic stress resistance to both low nutrient and drought stress. However, to date, there have only been a few genes reported to be related with abiotic stress resistance in foxtail millet. In this study, we identified an autophagy-related gene, SiATG8a, from foxtail millet. SiATG8a is mainly expressed in stems and its expression was dramatically induced by drought stress and nitrogen starvation treatments. SiATG8a was localized in the membrane and cytoplasm of foxtail millet. Overexpression of SiATG8a in Arabidopsis conferred tolerance to both nitrogen starvation and to drought stress. Under nitrogen starvation conditions, the SiATG8a transgenic plants had larger root and leaf areas and accumulated more total nitrogen than wild-type plants. The transgenic plants had lower total protein concentrations than did the WT plants. Under drought stress, the SiATG8a transgenic plants had higher survival rates, chlorophyll content, and proline content, but had lower MDA content than wild type plants. Taken together, our results represent the first identified case where overexpression of autophagy related gene can simultaneously improve plant resistance to low nitrogen and drought stresses. These findings implicate plant autophagy in plant stress responses to low nitrogen and drought and should be helpful in efforts to improve stresses resistance to nitrogen starvation and drought of crops by genetic transformation. PMID:26577407

  5. Autophagy: for better or for worse

    PubMed Central

    Wirawan, Ellen; Berghe, Tom Vanden; Lippens, Saskia; Agostinis, Patrizia; Vandenabeele, Peter

    2012-01-01

    Autophagy is a lysosomal degradation pathway that degrades damaged or superfluous cell components into basic biomolecules, which are then recycled back into the cytosol. In this respect, autophagy drives a flow of biomolecules in a continuous degradation-regeneration cycle. Autophagy is generally considered a pro-survival mechanism protecting cells under stress or poor nutrient conditions. Current research clearly shows that autophagy fulfills numerous functions in vital biological processes. It is implicated in development, differentiation, innate and adaptive immunity, ageing and cell death. In addition, accumulating evidence demonstrates interesting links between autophagy and several human diseases and tumor development. Therefore, autophagy seems to be an important player in the life and death of cells and organisms. Despite the mounting knowledge about autophagy, the mechanisms through which the autophagic machinery regulates these diverse processes are not entirely understood. In this review, we give a comprehensive overview of the autophagic signaling pathway, its role in general cellular processes and its connection to cell death. In addition, we present a brief overview of the possible contribution of defective autophagic signaling to disease. PMID:21912435

  6. Autophagy mediates degradation of nuclear lamina

    PubMed Central

    Dou, Zhixun; Xu, Caiyue; Donahue, Greg; Shimi, Takeshi; Pan, Ji-An; Zhu, Jiajun; Ivanov, Andrejs; Capell, Brian C.; Drake, Adam M.; Shah, Parisha P.; Catanzaro, Joseph M.; Ricketts, M. Daniel; Lamark, Trond; Adam, Stephen A.; Marmorstein, Ronen; Zong, Wei-Xing; Johansen, Terje; Goldman, Robert D.; Adams, Peter D.; Berger, Shelley L.

    2015-01-01

    Macroautophagy (hereafter referred to as autophagy) is a catabolic membrane trafficking process that degrades a variety of cellular constituents, and is associated with human diseases1–3. While extensive studies have focused on autophagic turnover of cytoplasmic materials, little is known regarding the role of autophagy in degrading nuclear components. Here we report that the autophagy machinery mediates degradation of nuclear lamina components in mammals. The autophagy protein LC3/Atg8, which is involved in autophagy membrane trafficking and substrate delivery4–6, is present in the nucleus and directly interacts with the nuclear lamina protein Lamin B1, and binds to lamin-associated domains (LADs) on chromatin. This LC3-Lamin B1 interaction does not downregulate Lamin B1 during starvation, but mediates its degradation upon oncogenic insults, such as by activated Ras. Lamin B1 degradation is achieved by nucleus-to-cytoplasm transport that delivers Lamin B1 to the lysosome. Inhibiting autophagy or the LC3-Lamin B1 interaction prevents activated Ras-induced Lamin B1 loss and attenuates oncogene-induced senescence in primary human cells. Our study suggests this new function of autophagy as a guarding mechanism protecting cells from tumorigenesis. PMID:26524528

  7. Systems biology of the autophagy-lysosomal pathway

    PubMed Central

    Jegga, Anil G; Schneider, Lonnie; Ouyang, Xiaosen

    2011-01-01

    The mechanisms of the control and activity of the autophagy-lysosomal protein degradation machinery are emerging as an important theme for neurodevelopment and neurodegeneration. However, the underlying regulatory and functional networks of known genes controlling autophagy and lysosomal function and their role in disease are relatively unexplored. We performed a systems biology-based integrative computational analysis to study the interactions between molecular components and to develop models for regulation and function of genes involved in autophagy and lysosomal function. Specifically, we analyzed transcriptional and microRNA-based post-transcriptional regulation of these genes and performed functional enrichment analyses to understand their involvement in nervous system-related diseases and phenotypes. Transcriptional regulatory network analysis showed that binding sites for transcription factors, SREBP1, USF, AP-1 and NFE2, are common among autophagy and lysosomal genes. MicroRNA enrichment analysis revealed miR-130, 98, 124, 204 and 142 as the putative post-transcriptional regulators of the autophagy-lysosomal pathway genes. Pathway enrichment analyses revealed that the mTOR and insulin signaling pathways are important in the regulation of genes involved in autophagy. In addition, we found that glycosaminoglycan and glycosphingolipid pathways also make a major contribution to lysosomal gene regulation. The analysis confirmed the known contribution of the autophagy-lysosomal genes to Alzheimer and Parkinson diseases and also revealed potential involvement in tuberous sclerosis, neuronal ceroidlipofuscinoses, sepsis and lung, liver and prostatic neoplasms. To further probe the impact of autophagy-lysosomal gene deficits on neurologically-linked phenotypes, we also mined the mouse knockout phenotype data for the autophagy-lysosomal genes and found them to be highly predictive of nervous system dysfunction. Overall this study demonstrates the utility of systems

  8. Autophagy in granular corneal dystrophy type 2.

    PubMed

    Choi, Seung-Il; Kim, Eung Kweon

    2016-03-01

    Autophagy is a lysosomal degradative process that is essential for cellular homeostasis and metabolic stress adaptation. Defective autophagy is involved in the pathogenesis of many diseases including granular corneal dystrophy type 2 (GCD2). GCD2 is an autosomal dominant disorder caused by substitution of histidine for arginine at codon 124 (R124H) in the transforming growth factor β-induced gene (TGFBI) on chromosome 5q31. Transforming growth factor β-induced protein (TGFBIp) is degraded by autophagy, but mutant-TGFBIp accumulates in autophagosomes and/or lysosomes, despite significant activation of basal autophagy, in GCD2 corneal fibroblasts. Furthermore, inhibition of autophagy induces cell death of GCD2 corneal fibroblasts through active caspase-3. As there is currently no pharmacological treatment for GCD2, development of novel therapies is required. A potential strategy for preventing cytoplasmic accumulation of mutant-TGFBIp in GCD2 corneal fibroblasts is to enhance mutant-TGFBIp degradation. This could be achieved by activation of the autophagic pathway. Here, we will consider the role and the potential therapeutic benefits of autophagy in GCD2, with focus on TGFBIp degradation, in light of the recently established role of autophagy in protein degradation. PMID:26386150

  9. Guidelines for monitoring autophagy in Caenorhabditis elegans

    PubMed Central

    Zhang, Hong; Chang, Jessica T; Guo, Bin; Hansen, Malene; Jia, Kailiang; Kovács, Attila L; Kumsta, Caroline; Lapierre, Louis R; Legouis, Renaud; Lin, Long; Lu, Qun; Meléndez, Alicia; O'Rourke, Eyleen J; Sato, Ken; Sato, Miyuki; Wang, Xiaochen; Wu, Fan

    2015-01-01

    The cellular recycling process of autophagy has been extensively characterized with standard assays in yeast and mammalian cell lines. In multicellular organisms, numerous external and internal factors differentially affect autophagy activity in specific cell types throughout the stages of organismal ontogeny, adding complexity to the analysis of autophagy in these metazoans. Here we summarize currently available assays for monitoring the autophagic process in the nematode C. elegans. A combination of measuring levels of the lipidated Atg8 ortholog LGG-1, degradation of well-characterized autophagic substrates such as germline P granule components and the SQSTM1/p62 ortholog SQST-1, expression of autophagic genes and electron microscopy analysis of autophagic structures are presently the most informative, yet steady-state, approaches available to assess autophagy levels in C. elegans. We also review how altered autophagy activity affects a variety of biological processes in C. elegans such as L1 survival under starvation conditions, dauer formation, aging, and cell death, as well as neuronal cell specification. Taken together, C. elegans is emerging as a powerful model organism to monitor autophagy while evaluating important physiological roles for autophagy in key developmental events as well as during adulthood. PMID:25569839

  10. Role of Autophagy in the Maintenance of Intestinal Homeostasis

    PubMed Central

    Baxt, Leigh A.; Xavier, Ramnik J.

    2015-01-01

    Genome-wide association studies of inflammatory bowel disease have identified several risk loci in genes that regulate autophagy, and studies have provided insight into the functional effects of these polymorphisms. We review the mechanisms by which autophagy contributes to intestinal homeostasis, focusing on its cell type-specific roles in regulating gut ecology, restricting pathogenic bacteria, and controlling inflammation. Based on this information, we are beginning to understand how alterations in autophagy can contribute to intestinal inflammation. PMID:26170139

  11. On the role of autophagy in human diseases: a gender perspective

    PubMed Central

    Lista, Pasquale; Straface, Elisabetta; Brunelleschi, Sandra; Franconi, Flavia; Malorni, Walter

    2011-01-01

    Abstract Cytopathological features of cells from males and females, i.e. XX and XY isolated cells, have been demonstrated to represent a key variable in the mechanism underlying gender disparity in human diseases. Major insights came from the studies of gender differences in cell fate, e.g. in apoptotic susceptibility. We report here some novel insights recently emerged from literature that are referred as to a cytoprotection mechanism by which cells recycle cytoplasm and dispose of excess or defective organelles, i.e. autophagy. Autophagy and related genes have first been identified in yeast. Orthologue genes have subsequently been found in other organisms, including human beings. This stimulated the research in the field and, thanks to the use of molecular genetics and cell biology in different model systems, autophagy gained the attention of several research groups operating to analyse the pathogenetic mechanisms of human diseases. It remains unclear, however, whether autophagy can exert a protective effect or instead contribute to the pathogenesis of important human diseases. On the basis of the growing importance of sex/gender as key determinant of human pathology and of the known differences between males and females in the onset, progression, drug susceptibility and outcome of a plethora of diseases, the idea that autophagy could represent key and critical factor should be taken into account. In the review, we summarize our current knowledge about the role of autophagy in some paradigmatic human diseases (cancer, neurodegenerative, autoimmune, cardiovascular) and the role of ‘cell sex’ differences in this context. PMID:21362130

  12. WT1 is involved in the Akt-JNK pathway dependent autophagy through directly regulating Gas1 expression in human osteosarcoma cells.

    PubMed

    Mo, Hao; He, Juliang; Yuan, Zhenchao; Mo, Ligen; Wu, Zhenjie; Lin, Xiang; Liu, Bin; Guan, Jian

    2016-09-01

    Macroautophagy (herein termed autophagy) works as a protective mechanism in tumorigenesis and development under metabolic stress condition. Multitudes of genes have been found involved in this process during past decades. In the present study, we report that Wilm's tumor suppressor1 (WT1) is involved in autophagy in osteosarcoma (OS) cells. WT1, a transcription factor with multitude of target genes, expresses in a majority of cancer types. Though wide-ranging effect of WT1 is now well documented, the function of WT1 in tumors remains poorly defined. In this chapter, it is found that high expression of WT1 positively correlates with active autophagy in human osteosarcoma cells. And further study on cell signaling pathway illustrates that Akt/JNK pathway acts as a positive regulator of autophagy induced by WT1. Here, we present evidence that WT1 modulates Akt/JNK signaling pathway mediated autophagy by controlling the expression of growth arrest-specific 1 (Gas1). We show that WT1 is required for Gas1 transcription in osteosarcoma cells. And Gas1 is upregulated followed WT1 overexpression in a time-dependent manner. Loss of Gas1 results in a reduction of WT1-induced autophagy. PMID:27453337

  13. Neferine attenuates the protein level and toxicity of mutant huntingtin in PC-12 cells via induction of autophagy.

    PubMed

    Wong, Vincent Kam Wai; Wu, An Guo; Wang, Jing Rong; Liu, Liang; Law, Betty Yuen-Kwan

    2015-01-01

    Mutant huntingtin aggregation is highly associated with the pathogenesis of Huntington's disease, an adult-onset autosomal dominant disorder, which leads to a loss of motor control and decline in cognitive function. Recent literature has revealed the protective role of autophagy in neurodegenerative diseases through degradation of mutant toxic proteins, including huntingtin or a-synuclein. Through the GFP-LC3 autophagy detection platform, we have  identified  neferine,  isolated  from  the  lotus  seed  embryo  of Nelumbo nucifera, which is able to induce autophagy through an AMPK-mTOR-dependent pathway. Furthermore, by overexpressing huntingtin with 74 CAG repeats (EGFP-HTT 74) in PC-12 cells, neferine reduces both the protein level and toxicity of mutant huntingtin through an autophagy-related gene 7 (Atg7)-dependent mechanism. With the variety of novel active compounds present in medicinal herbs, our current study suggests the possible protective mechanism of an autophagy inducer isolated from Chinese herbal medicine, which is crucial for its further development into a potential therapeutic agent for neurodegenerative disorders in the future. PMID:25699594

  14. The V471A polymorphism in autophagy-related gene ATG7 modifies age at onset specifically in Italian Huntington disease patients.

    PubMed

    Metzger, Silke; Walter, Carolin; Riess, Olaf; Roos, Raymund A C; Nielsen, Jørgen E; Craufurd, David; Nguyen, Huu Phuc

    2013-01-01

    The cause of Huntington disease (HD) is a polyglutamine repeat expansion of more than 36 units in the huntingtin protein, which is inversely correlated with the age at onset of the disease. However, additional genetic factors are believed to modify the course and the age at onset of HD. Recently, we identified the V471A polymorphism in the autophagy-related gene ATG7, a key component of the autophagy pathway that plays an important role in HD pathogenesis, to be associated with the age at onset in a large group of European Huntington disease patients. To confirm this association in a second independent patient cohort, we analysed the ATG7 V471A polymorphism in additional 1,464 European HD patients of the "REGISTRY" cohort from the European Huntington Disease Network (EHDN). In the entire REGISTRY cohort we could not confirm a modifying effect of the ATG7 V471A polymorphism. However, analysing a modifying effect of ATG7 in these REGISTRY patients and in patients of our previous HD cohort according to their ethnic origin, we identified a significant effect of the ATG7 V471A polymorphism on the HD age at onset only in the Italian population (327 patients). In these Italian patients, the polymorphism is associated with a 6-years earlier disease onset and thus seems to have an aggravating effect. We could specify the role of ATG7 as a genetic modifier for HD particularly in the Italian population. This result affirms the modifying influence of the autophagic pathway on the course of HD, but also suggests population-specific modifying mechanisms in HD pathogenesis. PMID:23894380

  15. The V471A Polymorphism in Autophagy-Related Gene ATG7 Modifies Age at Onset Specifically in Italian Huntington Disease Patients

    PubMed Central

    Metzger, Silke; Walter, Carolin; Riess, Olaf; Roos, Raymund A. C.; Nielsen, Jørgen E.; Craufurd, David; Nguyen, Huu Phuc

    2013-01-01

    The cause of Huntington disease (HD) is a polyglutamine repeat expansion of more than 36 units in the huntingtin protein, which is inversely correlated with the age at onset of the disease. However, additional genetic factors are believed to modify the course and the age at onset of HD. Recently, we identified the V471A polymorphism in the autophagy-related gene ATG7, a key component of the autophagy pathway that plays an important role in HD pathogenesis, to be associated with the age at onset in a large group of European Huntington disease patients. To confirm this association in a second independent patient cohort, we analysed the ATG7 V471A polymorphism in additional 1,464 European HD patients of the “REGISTRY” cohort from the European Huntington Disease Network (EHDN). In the entire REGISTRY cohort we could not confirm a modifying effect of the ATG7 V471A polymorphism. However, analysing a modifying effect of ATG7 in these REGISTRY patients and in patients of our previous HD cohort according to their ethnic origin, we identified a significant effect of the ATG7 V471A polymorphism on the HD age at onset only in the Italian population (327 patients). In these Italian patients, the polymorphism is associated with a 6-years earlier disease onset and thus seems to have an aggravating effect. We could specify the role of ATG7 as a genetic modifier for HD particularly in the Italian population. This result affirms the modifying influence of the autophagic pathway on the course of HD, but also suggests population-specific modifying mechanisms in HD pathogenesis. PMID:23894380

  16. Measurement of autophagy flux in the nervous system in vivo

    PubMed Central

    Castillo, K; Valenzuela, V; Matus, S; Nassif, M; Oñate, M; Fuentealba, Y; Encina, G; Irrazabal, T; Parsons, G; Court, F A; Schneider, B L; Armentano, D; Hetz, C

    2013-01-01

    Accurate methods to measure autophagic activity in vivo in neurons are not available, and most of the studies are based on correlative and static measurements of autophagy markers, leading to conflicting interpretations. Autophagy is an essential homeostatic process involved in the degradation of diverse cellular components including organelles and protein aggregates. Autophagy impairment is emerging as a relevant factor driving neurodegeneration in many diseases. Moreover, strategies to modulate autophagy have been shown to provide protection against neurodegeneration. Here we describe a novel and simple strategy to express an autophagy flux reporter in the nervous system of adult animals by the intraventricular delivery of adeno-associated viruses (AAV) into newborn mice. Using this approach we efficiently expressed a monomeric tandem mCherry-GFP-LC3 construct in neurons of the peripheral and central nervous system, allowing the measurement of autophagy activity in pharmacological and disease settings. PMID:24232093

  17. Autosis and autophagic cell death: the dark side of autophagy

    PubMed Central

    Liu, Y; Levine, B

    2015-01-01

    It is controversial whether cells truly die via autophagy or whether — in dying cells — autophagy is merely an innocent bystander or a well-intentioned ‘Good Samaritan' trying to prevent inevitable cellular demise. However, there is increasing evidence that the genetic machinery of autophagy may be essential for cell death in certain settings. We recently identified a novel form of autophagy gene-dependent cell death, termed autosis, which is mediated by the Na+,K+-ATPase pump and has unique morphological features. High levels of cellular autophagy, as occurs with treatment with autophagy-inducing peptides, starvation, or in vivo during certain types of ischemia, can trigger autosis. These findings provide insights into the mechanisms and strategies for prevention of cell death during extreme stress conditions. PMID:25257169

  18. Autosis and autophagic cell death: the dark side of autophagy.

    PubMed

    Liu, Y; Levine, B

    2015-03-01

    It is controversial whether cells truly die via autophagy or whether - in dying cells - autophagy is merely an innocent bystander or a well-intentioned 'Good Samaritan' trying to prevent inevitable cellular demise. However, there is increasing evidence that the genetic machinery of autophagy may be essential for cell death in certain settings. We recently identified a novel form of autophagy gene-dependent cell death, termed autosis, which is mediated by the Na(+),K(+)-ATPase pump and has unique morphological features. High levels of cellular autophagy, as occurs with treatment with autophagy-inducing peptides, starvation, or in vivo during certain types of ischemia, can trigger autosis. These findings provide insights into the mechanisms and strategies for prevention of cell death during extreme stress conditions. PMID:25257169

  19. AEG-1/MTDH-activated autophagy enhances human malignant glioma susceptibility to TGF-β1-triggered epithelial-mesenchymal transition

    PubMed Central

    Zou, Meijuan; Zhu, Wei; Wang, Li; Shi, Lei; Gao, Rui; Ou, Yingwei; Chen, Xuguan; Wang, Zhongchang; Jiang, Aiqin; Liu, Kunmei; Xiao, Ming; Ni, Ping; Wu, Dandan; He, Wenping; Sun, Geng; Li, Ping; Zhai, Sulan; Wang, Xuerong; Hu, Gang

    2016-01-01

    Autophagy is a tightly regulated process activated in response to metabolic stress and other microenvironmental changes. Astrocyte elevated gene 1 (AEG-1) reportedly induces protective autophagy. Our results indicate that AEG-1 also enhances the susceptibility of malignant glioma cells to TGF-β1-triggered epithelial-mesenchymal transition (EMT) through induction of autophagy. TGF-β1 induced autophagy and activated AEG-1 via Smad2/3 phosphorylation in malignant glioma cells. Also increased was oncogene cyclin D1 and EMT markers, which promoted tumor progression. Inhibition of autophagy using siRNA-BECN1 and siRNA-AEG-1 suppressed EMT. In tumor samples from patients with malignant glioma, immunohistochemical assays showed that expression levels of TGF-β1, AEG-1, and markers of autophagy and EMT, all gradually increase with glioblastoma progression. In vivo siRNA-AEG-1 administration to rats implanted with C6 glioma cells inhibited tumor growth and increased the incidence of apoptosis among tumor cells. These findings shed light on the mechanisms underlying the invasiveness and progression of malignant gliomas. PMID:26909607

  20. NF-κB activation was involved in reactive oxygen species-mediated apoptosis and autophagy in 1-oxoeudesm-11(13)-eno-12,8α-lactone-treated human lung cancer cells.

    PubMed

    Liu, Shanshan; Wu, Di; Li, Lin; Sun, Xiao; Xie, Weidong; Li, Xia

    2014-08-01

    1-oxoeudesm-11(13)-eno-12,8α-lactone (OEL), a novel eudesmane-type sesquiterpene compound, has been shown to inhibit the growth of some cancer cell lines and induce significant apoptosis. Here, we investigated the anti-cancer activities of OEL in human lung cancer cells. Our studies demonstrated that OEL induced both apoptosis and autophagy in A549 and H460 cells. OEL-induced autophagy was assessed by appearance of autophagic vacuoles, formation of acidic vesicular organelles, conversion of LC3-I to LC3-II, recruitment of LC3-II to the autophagosomes, and activation of autophagy genes. Furthermore, administration of autophagic inhibitor 3-methyladenine augments OEL-induced apoptotic cell death. The induction of autophagy and apoptosis by OEL links to NF-κB activation and the generation of reactive oxygen species (ROS). Interruption of NF-κB activation by specific inhibitor promotes apoptosis, but decreases autophagy. ROS antioxidants (N-acetylcysteine) attenuated both OEL-induced autophagy and apoptosis. Further experiments confirmed that OEL-induced activation of ROS was increased by NF-κB inhibitor whereas NF-κB activation was not affected by ROS inhibition. These findings suggest that OEL-elicited autophagic response plays a protective role that impedes cell death, and inhibition of autophagy could be an adjunctive strategy for enhancing the chemotherapeutic effect of OEL as an antitumor agent. PMID:24194260

  1. Autophagy and mitophagy in diabetic cardiomyopathy.

    PubMed

    Kobayashi, Satoru; Liang, Qiangrong

    2015-02-01

    Diabetic cardiomyopathy is a heart muscle-specific disease that increases the risk of heart failure and mortality in diabetic patients independent of vascular pathology. Mitochondria are cellular power plants that generate energy for heart contraction and concurrently produce reactive oxygen species that, if unchecked, may damage the mitochondria and the heart. Elimination of damaged mitochondria by autophagy known as mitophagy is an essential process for maintaining normal cardiac function at baseline and in response to various stress and disease conditions. Mitochondrial structural injury and functional impairment have been shown to contribute to diabetic heart disease. Recent studies have demonstrated an inhibited autophagic flux in the hearts of diabetic animals. Surprisingly, the diminished autophagy appears to be an adaptive response that protects against cardiac injury in type 1 diabetes. This raises several questions regarding the relationship between general autophagy and selective mitophagy in the diabetic heart. However, autophagy may play a different role in the hearts of type 2 diabetic animals. In this review, we will summarize current knowledge in this field and discuss the potential functional roles of autophagy and mitophagy in the pathogenesis of diabetic cardiomyopathy. This article is part of a Special Issue entitled: Autophagy and protein quality control in cardiometabolic diseases. PMID:24882754

  2. RUFY4: Immunity piggybacking on autophagy?

    PubMed

    Terawaki, Seigo; Camosseto, Voahirana; Pierre, Philippe; Gatti, Evelina

    2016-03-01

    Although autophagy is a highly conserved mechanism among species and cell types, few are the molecules involved with the autophagic process that display cell- or tissue- specific expression. We have unraveled the positive regulatory role on autophagy of RUFY4 (RUN and FYVE domain containing 4), which is expressed in subsets of immune cells, including dendritic cells (DCs). DCs orchestrate the eradication of pathogens by coordinating the action of the different cell types involved in microbe recognition and destruction during the immune response. To fulfill this function, DC display particular regulation of their endocytic and autophagy pathways in response to the immune environment. Autophagy flux is downmodulated in DCs upon microbe sensing, but is remarkably augmented, when cells are differentiated in the presence of the pleiotropic cytokine IL4 (interleukin 4). From gene expression studies aimed at comparing the impact of IL4 on DC differentiation, we identified RUFY4, as a novel regulator that augments autophagy flux and, when overexpressed, induces drastic membrane redistribution and strongly tethers lysosomes. RUFY4 is therefore one of the few known positive regulators of autophagy that is expressed in a cell-specific manner or under specific immunological conditions associated with IL4 expression such as allergic asthma. PMID:26760128

  3. Protective roles of aldo-keto reductase 1B10 and autophagy against toxicity induced by p-quinone metabolites of tert-butylhydroquinone in lung cancer A549 cells.

    PubMed

    Endo, Satoshi; Nishiyama, Ayako; Suyama, Miho; Takemura, Mayuko; Soda, Midori; Chen, Huayue; Tajima, Kazuo; El-Kabbani, Ossama; Bunai, Yasuo; Hara, Akira; Matsunaga, Toshiyuki; Ikari, Akira

    2015-06-01

    tert-Butylhydroquinone (BHQ), an antioxidant used as a food additive, exhibits an anticancer effect at low doses, but is carcinogenic in rodents at high doses. BHQ is metabolized into cytotoxic tert-butylquinone (TBQ), which is further converted to 6-tert-butyl-2,3-epoxy-4-hydroxy-5-cyclohexen-1-one (TBEH) through 6-tert-butyl-2,3-epoxy-4-benzoquinone (TBE). Both TBQ and TBE are cytotoxic, but their toxic mechanisms have not been fully characterized. In this study, we have investigated the toxic mechanisms of TBQ and TBE, and the defense system against the two p-quinones using lung cancer A549 cells. TBQ and TBE, but not BHQ and TBEH, showed cytotoxicity to A549 cells. Neither caspase-3 activation nor an increase in the expression of endoplasmic reticulum stress-associating target genes was observed. TBQ and TBE reacted with reduced glutathione, and significantly decreased the glutathione level in A549 cells, suggesting that the cytotoxicity of the p-quinones is caused by their high electrophilicity reacting with biomolecules. The A549 cells treated with the p-quinones also showed increased levels of autophagic vacuoles and LC3-II protein, which are specific autophagy markers. An autophagy inhibitor, 3-methyladenine (3MA), decreased the LC3-II production by the p-quinones, but enhanced the cytotoxicity induced by TBQ and TBE, suggesting that autophagy contributes to alleviating the p-quinone-triggered cytotoxicity. In addition, the TBE-induced cytotoxicity and autophagy activation in the cells were significantly suppressed by overexpression of aldo-keto reductase (AKR)1B10 that efficiently reduces TBE into TBEH, and were augmented by pretreatment with a potent AKR1B10 inhibitor, C1. The effects of 3MA and C1 on the TBE-induced cytotoxicity were additive. The data provides evidence for the first time that autophagy and AKR1B10 contribute to the defense system against the cytotoxicity caused by the electrophilic p-quinone metabolites of BHQ. PMID:25289770

  4. Dysregulation of autophagy in human follicular lymphoma is independent of overexpression of BCL-2

    PubMed Central

    McCarthy, Aine; Marzec, Jacek; Clear, Andrew; Petty, Robert D.; Coutinho, Rita; Matthews, Janet; Wilson, Andrew; Iqbal, Sameena; Calaminici, Maria; Gribben, John G.; Jia, Li

    2014-01-01

    Overexpression of the anti-apoptotic protein BCL-2 is characteristic of human follicular lymphoma (FL) and some cases of diffuse large B cell lymphoma (DLBCL). We aimed to determine autophagy status in primary FL and DLBCL samples and the BCL-2+/BCL-2− lymphoma cell lines using both autophagy PCR array and tissue microarray (TMA). A greater number of autophagy machinery genes were up-regulated in the BCL-2+ Su-DHL4 cell line compared with BCL-2− Su-DHL8 cells, at both the basal level and in response to autophagic stress. The autophagy-related gene expression profiles were determined in purified and unpurified malignant human lymph node biopsies. Seven autophagy machinery genes were up-regulated in purified FL B-cells compared with reactive B-cells. Only 2 autophagy machinery genes were up-regulated in DLBCL B-cells. In unpurified tissue biopsies, 20 of 46 genes in FL and 2 of 5 genes in DLBCL with increased expression were autophagy machinery genes. Expression of autophagy substrates p62 and LC3 were determined by TMAs. FL samples showed significantly decreased levels of both p62 and LC3 compared with reactive and DLBCL, indicative of an increased autophagy activity in FL. In summary, these results demonstrate that FL showed increased basal autophagy activity, regardless of overexpression of BCL-2 in this disease. PMID:25362242

  5. Dysregulated autophagy in the RPE is associated with increased susceptibility to oxidative stress and AMD

    PubMed Central

    Mitter, Sayak K; Song, Chunjuan; Qi, Xiaoping; Mao, Haoyu; Rao, Haripriya; Akin, Debra; Lewin, Alfred; Grant, Maria; Dunn, William; Ding, Jindong; Bowes Rickman, Catherine; Boulton, Michael

    2014-01-01

    Autophagic dysregulation has been suggested in a broad range of neurodegenerative diseases including age-related macular degeneration (AMD). To test whether the autophagy pathway plays a critical role to protect retinal pigmented epithelial (RPE) cells against oxidative stress, we exposed ARPE-19 and primary cultured human RPE cells to both acute (3 and 24 h) and chronic (14 d) oxidative stress and monitored autophagy by western blot, PCR, and autophagosome counts in the presence or absence of autophagy modulators. Acute oxidative stress led to a marked increase in autophagy in the RPE, whereas autophagy was reduced under chronic oxidative stress. Upregulation of autophagy by rapamycin decreased oxidative stress-induced generation of reactive oxygen species (ROS), whereas inhibition of autophagy by 3-methyladenine (3-MA) or by knockdown of ATG7 or BECN1 increased ROS generation, exacerbated oxidative stress-induced reduction of mitochondrial activity, reduced cell viability, and increased lipofuscin. Examination of control human donor specimens and mice demonstrated an age-related increase in autophagosome numbers and expression of autophagy proteins. However, autophagy proteins, autophagosomes, and autophagy flux were significantly reduced in tissue from human donor AMD eyes and 2 animal models of AMD. In conclusion, our data confirm that autophagy plays an important role in protection of the RPE against oxidative stress and lipofuscin accumulation and that impairment of autophagy is likely to exacerbate oxidative stress and contribute to the pathogenesis of AMD. PMID:25484094

  6. Nucleofection of Rat Pheochromocytoma PC-12 Cells with Human Mutated Beta-Amyloid Precursor Protein Gene (APP-sw) Leads to Reduced Viability, Autophagy-Like Process, and Increased Expression and Secretion of Beta Amyloid

    PubMed Central

    Pająk, Beata; Kania, Elżbieta

    2015-01-01

    Pheochromocytoma PC-12 cells are immune to physiological stimuli directed to evoke programmed cell death. Besides, metabolic inhibitors are incapable of sensitizing PC-12 cells to extrinsic or intrinsic apoptosis unless they are used in toxic concentrations. Surprisingly, these cells become receptive to cell deletion after human APP-sw gene expression. We observed reduced cell viability in GFP vector + APP-sw-nucleofected cells (drop by 36%) but not in GFP vector − or GFP vector + APP-wt-nucleofected cells. Lower viability was accompanied by higher expression of Aβ 1-16 and elevated secretion of Aβ 1-40 (in average 53.58 pg/mL). At the ultrastructural level autophagy-like process was demonstrated to occur in APP-sw-nucleofected cells with numerous autophagosomes and multivesicular bodies but without autolysosomes. Human APP-sw gene is harmful to PC-12 cells and cells are additionally driven to incomplete autophagy-like process. When stimulated by TRAIL or nystatin, CLU protein expression accompanies early phase of autophagy. PMID:25821818

  7. Autophagy in vascular disease.

    PubMed

    Ryter, Stefan W; Lee, Seon-Jin; Smith, Akaya; Choi, Augustine M K

    2010-02-01

    Autophagy, or "self eating," refers to a regulated cellular process for the lysosomal-dependent turnover of organelles and proteins. During starvation or nutrient deficiency, autophagy promotes survival through the replenishment of metabolic precursors derived from the degradation of endogenous cellular components. Autophagy represents a general homeostatic and inducible adaptive response to environmental stress, including endoplasmic reticulum stress, hypoxia, oxidative stress, and exposure to pharmaceuticals and xenobiotics. Whereas elevated autophagy can be observed in dying cells, the functional relationships between autophagy and programmed cell death pathways remain incompletely understood. Preclinical studies have identified autophagy as a process that can be activated during vascular disorders, including ischemia-reperfusion injury of the heart and other organs, cardiomyopathy, myocardial injury, and atherosclerosis. The functional significance of autophagy in human cardiovascular disease pathogenesis remains incompletely understood, and potentially involves both adaptive and maladaptive outcomes, depending on model system. Although relatively few studies have been performed in the lung, our recent studies also implicate a role for autophagy in chronic lung disease. Manipulation of the signaling pathways that regulate autophagy could potentially provide a novel therapeutic strategy in the prevention or treatment of human disease. PMID:20160147

  8. Pharmacologic agents targeting autophagy

    PubMed Central

    Vakifahmetoglu-Norberg, Helin; Xia, Hong-guang; Yuan, Junying

    2015-01-01

    Autophagy is an important intracellular catabolic mechanism critically involved in regulating tissue homeostasis. The implication of autophagy in human diseases and the need to understand its regulatory mechanisms in mammalian cells have stimulated research efforts that led to the development of high-throughput screening protocols and small-molecule modulators that can activate or inhibit autophagy. Herein we review the current landscape in the development of screening technology as well as the molecules and pharmacologic agents targeting the regulatory mechanisms of autophagy. We also evaluate the potential therapeutic application of these compounds in different human pathologies. PMID:25654545

  9. Autophagy in renal diseases.

    PubMed

    De Rechter, Stéphanie; Decuypere, Jean-Paul; Ivanova, Ekaterina; van den Heuvel, Lambertus P; De Smedt, Humbert; Levtchenko, Elena; Mekahli, Djalila

    2016-05-01

    Autophagy is the cell biology process in which cytoplasmic components are degraded in lysosomes to maintain cellular homeostasis and energy production. In the healthy kidney, autophagy plays an important role in the homeostasis and viability of renal cells such as podocytes and tubular epithelial cells and of immune cells. Recently, evidence is mounting that (dys)regulation of autophagy is implicated in the pathogenesis of various renal diseases, and might be an attractive target for new renoprotective therapies. In this review, we provide an overview of the role of autophagy in kidney physiology and kidney diseases. PMID:26141928

  10. Autophagy is Required for Glucose Homeostasis and Lung Tumor Maintenance

    PubMed Central

    Karsli-Uzunbas, Gizem; Guo, Jessie Yanxiang; Price, Sandy; Teng, Xin; Laddha, Saurabh V.; Khor, Sinan; Kalaany, Nada Y.; Jacks, Tyler; Chan, Chang S.; Rabinowitz, Joshua D.; White, Eileen

    2014-01-01

    Macroautophagy (autophagy hereafter) recycles intracellular components to sustain mitochondrial metabolism that promotes the growth, stress tolerance and malignancy of lung cancers, suggesting that autophagy inhibition may have antitumor activity. To assess the functional significance of autophagy in both normal and tumor tissue, we conditionally deleted the essential autophagy gene, autophagy-related-7, Atg7, throughout adult mice. Here we report that systemic ATG7 ablation caused susceptibility to infection and neurodegeneration that limited survival to 2–3 months. Moreover, upon fasting, autophagy-deficient mice suffered fatal hypoglycemia. Prior autophagy ablation did not alter the efficiency of non-small-cell lung cancer (NSCLC) initiation by activation of oncogenic KrasG12D and deletion of the Trp53 tumor suppressor. Acute autophagy ablation in mice with pre-existing NSCLC, however, blocked tumor growth, promoted tumor cell death, and generated more benign disease (oncocytomas). This anti-tumor activity occurred prior to destruction of normal tissues, suggesting that, acute autophagy inhibition may be therapeutically beneficial in cancer. PMID:24875857

  11. Autophagy and selective deployment of Atg proteins in antiviral defense

    PubMed Central

    2013-01-01

    Autophagy is an evolutionarily ancient process eukaryotic cells utilize to remove and recycle intracellular material in order to maintain cellular homeostasis. In metazoans, the autophagy machinery not only functions in this capacity but also has evolved to perform a diverse repertoire of intracellular transport and regulatory functions. In response to virus infections, the autophagy machinery degrades viruses, shuttles viral pathogen-associated molecular patterns to endosomes containing Toll-like receptors, facilitates viral-antigen processing for major histocompatibility complex presentation and transports antiviral proteins to viral replication sites. This is accomplished through canonical autophagy or through processes involving distinct subsets of the autophagy-related genes (Atgs). Herein, we discuss how the variable components of the autophagy machinery contribute to antiviral defense and highlight three emerging themes: first, autophagy delivers viral cytosolic components to several distinct endolysosomal compartments; second, Atg proteins act alone, as subgroups or collectively; and third, the specificity of autophagy and the autophagy machinery is achieved by recognition of triggers and selective targeting by adaptors. PMID:23042773

  12. The interplay between autophagy and ROS in tumorigenesis

    PubMed Central

    Kongara, Sameera; Karantza, Vassiliki

    2012-01-01

    Reactive oxygen species (ROS) at physiological levels are important cell signaling molecules. However, aberrantly high ROS are intimately associated with disease and commonly observed in cancer. Mitochondria are primary sources of intracellular ROS, and their maintenance is essential to cellular health. Autophagy, an evolutionarily conserved process whereby cytoplasmic components are delivered to lysosomes for degradation, is responsible for mitochondrial turnover and removal of damaged mitochondria. Impaired autophagy is implicated in many pathological conditions, including neurological disorders, inflammatory bowel disease, diabetes, aging, and cancer. The first reports connecting autophagy to cancer showed that allelic loss of the essential autophagy gene BECLIN1 (BECN1) is prevalent in human breast, ovarian, and prostate cancers and that Becn1+/- mice develop mammary gland hyperplasias, lymphomas, lung and liver tumors. Subsequent studies demonstrated that Atg5-/- and Atg7-/- livers give rise to adenomas, Atg4C-/- mice are susceptible to chemical carcinogenesis, and Bif1-/- mice are prone to spontaneous tumors, indicating that autophagy defects promote tumorigenesis. Due to defective mitophagy, autophagy-deficient cells accumulate damaged mitochondria and deregulated ROS levels, which likely contribute to their tumor-initiating capacity. However, the role of autophagy in tumorigenesis is complex, as more recent work also revealed tumor dependence on autophagy: autophagy-competent mutant-Ras-expressing cells form tumors more efficiently than their autophagy-deficient counterparts; similarly, FIP200 deficiency suppresses PyMT-driven mammary tumorigenesis. These latter findings are attributed to the fact that tumors driven by powerful oncogenes have high metabolic demands catered to by autophagy. In this review, we discuss the relationship between ROS and autophagy and summarize our current knowledge on their functional interactions in tumorigenesis. PMID:23181220

  13. Autophagy in the Eye: Implications for Ocular Cell Health

    PubMed Central

    Frost, Laura S.; Mitchell, Claire H.; Boesze-Battaglia, Kathleen

    2014-01-01

    Autophagy, a catabolic process by which a cell “eats” itself, turning over its own cellular constituents, plays a key role in cellular homeostasis. In an effort to maintain normal cellular function, autophagy is often up-regulated in response to environmental stresses and excessive organelle damage to facilitate aggregated protein removal. In the eye, virtually all cell types from those comprising the cornea in the front of the eye to the retinal pigment epithelium (RPE) providing a protective barrier for the retina at the back of the eye, rely on one or more aspects of autophagy to maintain structure and/or normal physiological function. In the lens autophagy plays a critical role in lens fiber cell maturation and the formation of the organelle free zone. Numerous studies delineating the role of Atg5, Vsp34 as well as FYCO1 in maintenance of lens transparency are discussed. Corneal endothelial dystrophies are also characterized as having elevated levels of autophagic proteins. Therefore, novel modulators of autophagy such as lithium and melatonin are proposed as new therapeutic strategies for this group of dystrophies. In addition, we summarize how corneal Herpes Simplex Virus (HSV-1) infection subverts the cornea’s response to infection by inhibiting the normal autophagic response. Using glaucoma models we analyze the relative contribution of autophagy to cell death and cell survival. The cytoprotective role of autophagy is further discussed in an analysis of photoreceptor cell heath and function. We focus our analysis on the current understanding of autophagy in photoreceptor and RPE health, specifically on the diverse role of autophagy in rods and cones as well as its protective role in light induced degeneration. Lastly, in the RPE we highlight hybrid phagocytosis-autophagy pathways. This comprehensive review allows us to speculate on how alterations in various stages of autophagy contribute to glaucoma and retinal degenerations. PMID:24810222

  14. Conditional Depletion of the Chlamydomonas Chloroplast ClpP Protease Activates Nuclear Genes Involved in Autophagy and Plastid Protein Quality Control[W

    PubMed Central

    Ramundo, Silvia; Casero, David; Mühlhaus, Timo; Hemme, Dorothea; Sommer, Frederik; Crèvecoeur, Michèle; Rahire, Michèle; Schroda, Michael; Rusch, Jannette; Goodenough, Ursula; Pellegrini, Matteo; Perez-Perez, Maria Esther; Crespo, José Luis; Schaad, Olivier; Civic, Natacha; Rochaix, Jean David

    2014-01-01

    Plastid protein homeostasis is critical during chloroplast biogenesis and responses to changes in environmental conditions. Proteases and molecular chaperones involved in plastid protein quality control are encoded by the nucleus except for the catalytic subunit of ClpP, an evolutionarily conserved serine protease. Unlike its Escherichia coli ortholog, this chloroplast protease is essential for cell viability. To study its function, we used a recently developed system of repressible chloroplast gene expression in the alga Chlamydomonas reinhardtii. Using this repressible system, we have shown that a selective gradual depletion of ClpP leads to alteration of chloroplast morphology, causes formation of vesicles, and induces extensive cytoplasmic vacuolization that is reminiscent of autophagy. Analysis of the transcriptome and proteome during ClpP depletion revealed a set of proteins that are more abundant at the protein level, but not at the RNA level. These proteins may comprise some of the ClpP substrates. Moreover, the specific increase in accumulation, both at the RNA and protein level, of small heat shock proteins, chaperones, proteases, and proteins involved in thylakoid maintenance upon perturbation of plastid protein homeostasis suggests the existence of a chloroplast-to-nucleus signaling pathway involved in organelle quality control. We suggest that this represents a chloroplast unfolded protein response that is conceptually similar to that observed in the endoplasmic reticulum and in mitochondria. PMID:24879428

  15. Conditional Depletion of the Chlamydomonas Chloroplast ClpP Protease Activates Nuclear Genes Involved in Autophagy and Plastid Protein Quality Control.

    PubMed

    Ramundo, Silvia; Casero, David; Mühlhaus, Timo; Hemme, Dorothea; Sommer, Frederik; Crèvecoeur, Michèle; Rahire, Michèle; Schroda, Michael; Rusch, Jannette; Goodenough, Ursula; Pellegrini, Matteo; Perez-Perez, Maria Esther; Crespo, José Luis; Schaad, Olivier; Civic, Natacha; Rochaix, Jean David

    2014-05-30

    Plastid protein homeostasis is critical during chloroplast biogenesis and responses to changes in environmental conditions. Proteases and molecular chaperones involved in plastid protein quality control are encoded by the nucleus except for the catalytic subunit of ClpP, an evolutionarily conserved serine protease. Unlike its Escherichia coli ortholog, this chloroplast protease is essential for cell viability. To study its function, we used a recently developed system of repressible chloroplast gene expression in the alga Chlamydomonas reinhardtii. Using this repressible system, we have shown that a selective gradual depletion of ClpP leads to alteration of chloroplast morphology, causes formation of vesicles, and induces extensive cytoplasmic vacuolization that is reminiscent of autophagy. Analysis of the transcriptome and proteome during ClpP depletion revealed a set of proteins that are more abundant at the protein level, but not at the RNA level. These proteins may comprise some of the ClpP substrates. Moreover, the specific increase in accumulation, both at the RNA and protein level, of small heat shock proteins, chaperones, proteases, and proteins involved in thylakoid maintenance upon perturbation of plastid protein homeostasis suggests the existence of a chloroplast-to-nucleus signaling pathway involved in organelle quality control. We suggest that this represents a chloroplast unfolded protein response that is conceptually similar to that observed in the endoplasmic reticulum and in mitochondria. PMID:24879428

  16. Regulation of cardiac autophagy by insulin-like growth factor 1.

    PubMed

    Troncoso, Rodrigo; Díaz-Elizondo, Jessica; Espinoza, Sandra P; Navarro-Marquez, Mario F; Oyarzún, Alejandra P; Riquelme, Jaime A; Garcia-Carvajal, Ivonne; Díaz-Araya, Guillermo; García, Lorena; Hill, Joseph A; Lavandero, Sergio

    2013-07-01

    Insulin-like growth factor-1 (IGF-1) signaling is a key pathway in the control of cell growth and survival. Three critical nodes in the IGF-1 signaling pathway have been described in cardiomyocytes: protein kinase Akt/mammalian target of rapamycin (mTOR), Ras/Raf/extracellular signal-regulated kinase (ERK), and phospholipase C (PLC)/inositol 1,4,5-triphosphate (InsP3 )/Ca(2+) . The Akt/mTOR and Ras/Raf/ERK signaling arms govern survival in the settings of cardiac stress and hypertrophic growth. By contrast, PLC/InsP3 /Ca(2+) functions to regulate metabolic adaptability and gene transcription. Autophagy is a catabolic process involved in protein degradation, organelle turnover, and nonselective breakdown of cytoplasmic components during nutrient starvation or stress. In the heart, autophagy is observed in a variety of human pathologies, where it can be either adaptive or maladaptive, depending on the context. We proposed the hypothesis that IGF-1 protects the heart by rescuing the mitochondrial metabolism and the energetics state, reducing cell death and controls the potentially exacerbate autophagic response to nutritional stress. In light of the importance of IGF-1 and autophagy in the heart, we review here IGF-1 signaling and autophagy regulation in the context of cardiomyocyte nutritional stress. PMID:23671040

  17. Impairing autophagy in retinal pigment epithelium leads to inflammasome activation and enhanced macrophage-mediated angiogenesis

    PubMed Central

    Liu, Jian; Copland, David A.; Theodoropoulou, Sofia; Chiu, Hsi An Amy; Barba, Miriam Durazo; Mak, Ka Wang; Mack, Matthias; Nicholson, Lindsay B.; Dick, Andrew D.

    2016-01-01

    Age-related decreases in autophagy contribute to the progression of age-related macular degeneration (AMD). We have now studied the interaction between autophagy impaired in retinal pigment epithelium (RPE) and the responses of macrophages. We find that dying RPE cells can activate the macrophage inflammasome and promote angiogenesis. In vitro, inhibiting rotenone-induced autophagy in RPE cells elicits caspase-3 mediated cell death. Co-culture of damaged RPE with macrophages leads to the secretion of IL-1β, IL-6 and nitrite oxide. Exogenous IL-6 protects the dysfunctional RPE but IL-1β causes enhanced cell death. Furthermore, IL-1β toxicity is more pronounced in dysfunctional RPE cells showing reduced IRAK3 gene expression. Co-culture of macrophages with damaged RPE also elicits elevated levels of pro-angiogenic proteins that promote ex vivo choroidal vessel sprouting. In vivo, impaired autophagy in the eye promotes photoreceptor and RPE degeneration and recruitment of inflammasome-activated macrophages. The degenerative tissue environment drives an enhanced pro-angiogenic response, demonstrated by increased size of laser-induced choroidal neovascularization (CNV) lesions. The contribution of macrophages was confirmed by depletion of CCR2+ monocytes, which attenuates CNV in the presence of RPE degeneration. Our results suggest that the interplay between perturbed RPE homeostasis and activated macrophages influences key features of AMD development. PMID:26847702

  18. Gartanin induces autophagy through JNK activation which extenuates caspase-dependent apoptosis.

    PubMed

    Kim, Mun-Ock; Lee, Hyun-Sun; Chin, Young-Won; Moon, Dong-Oh; Ahn, Jong-Seog

    2015-07-01

    Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Development of novel agents to eradicate liver cancer cells is required for treatment of HCC. Gartanin, a xanthone-type compound isolated from mangosteen, is known to possess potent antioxidant, anti-inflammatory, antifungal and antineoplastic properties. In the present study, we investigated the cytotoxic effect of gartanin on HCC and explored the cell death mechanism. We showed that gartanin induced both the extrinsic and intrinsic apoptotic pathways, which were interconnected by caspase-8, -9 and -3 activation. We also provided convincing evidence that gartanin induced autophagy in various cancer cells, as demonstrated by acridine orange staining of intracellular acidic vesicles, the degradation of p62, the conversion of LC3-I to LC3-II and GFP-LC3 punctate fluorescence. Additionally, gartanin induced the formation of typical autophagosomes and autolysosomes and enhanced the degradation rate of intracellular granule(s), including mitochondria. Notably, gartanin-mediated apoptotic cell death was further potentiated by pretreatment with autophagy inhibitors (3-methyladenine and bafilomycin A1) or small interfering RNAs against the autophagic genes (Atg5). These findings suggested that gartanin-mediated autophagic response protected against eventual cell death induced by gartanin. Moreover, gartanin treatment led to phosphorylation/activation of JNK and JNK-dependent phosphorylation of Bcl-2. Importantly, JNK inhibitor (SP600125) inhibited autophagy yet promoted gartanin-induced apoptosis, indicating a key requirement of the JNK-Bcl-2 pathway in the activation of autophagy by gartanin. Taken together, our data suggested that the JNK-Bcl-2 pathway was the critical regulator of gartanin-induced protective autophagy and a potential drug target for chemotherapeutic combination. PMID:25955534

  19. Potential role of autophagy in smokeless tobacco extract-induced cytotoxicity and in morin-induced protection in oral epithelial cells.

    PubMed

    Ganguli, Arnab; Das, Amlan; Nag, Debasish; Bhattacharya, Surela; Chakrabarti, Gopal

    2016-04-01

    Toxic components of STE induced serious, adverse human oral health outcomes. In the present study, we observed that STE was involved in oral toxicity by reducing the viability of human squamous epithelial cells, SCC-25, along with the simultaneous induction of both apoptosis and autophagic signaling. STE was also found to induce significant amount ROS generation in SCC-25 cells. The dietary flavonoid morin, found abundantly in a variety of herbs, fruits and wine, has been reported to attenuate ROS-induced pathogenesis including autophagy. In this study we designed three different treatment regimes of morin treatment, such as pre, co, and post - treatment of STE challenged SCC-25 cells. In all cases morin provided cytoprotection to STE challenged SCC-25 cells by augmenting STE induced ROS-dependent cytotoxic autophagy. Hence, morin is a potential option for antioxidant therapy in treatment of STE induced toxicity. PMID:26891815

  20. mTOR-STAT3-notch signalling contributes to ALDH2-induced protection against cardiac contractile dysfunction and autophagy under alcoholism

    PubMed Central

    Ge, Wei; Ren, Jun

    2012-01-01

    Abstract Mitochondrial aldehyde dehydrogenase-2 (ALDH2) has been shown to benefit myopathic changes following alcohol intake, although the precise mechanism is still unclear. This study was designed to evaluate the role of ALDH2 on chronic alcohol intake-induced myocardial geometric and functional damage with a focus on autophagic signalling. Wild-type friendly virus B (FVB) and transgenic mice overexpressing ALDH2 driven by chicken β-actin promoter were fed a 4% alcohol liquid diet for 12 weeks. Cardiac geometry and function were assessed using echocardiographic and IonOptix systems. Western blot analysis was used to evaluate the essential autophagy markers, Akt and AMP-dependent protein kinase (AMPK) as well as their downstream signalling mammalian target of rapamycin (mTOR) and signal transducer and activator of transcription 3 (STAT3). Alcohol intake altered cardiac geometry and function as demonstrated by lessened LV wall and septal thickness, enlarged end systolic and diastolic diameters, decreased fractional shortening and cell shortening, the effects of which were mitigated by ALDH2 transgene. Chronic alcohol intake triggered myocardial autophagy as shown by LC3B II isoform switch, as well as decreased phosphorylation of mTOR, the effects of which were ablated by ALDH2. Chronic alcohol intake suppressed phosphorylation of Akt and AMPK, which was reconciled by ALDH2. Levels of Notch1 and STAT3 phosphorylation were dampened by chronic alcohol intake in FVB but not ALDH2 myocardium. Moreover, the γ-secretase Notch inhibitor N-[N-(3,5-difluorophenacetyl)-1-alany1]-S-phenyglycine t-butyl ester exacerbated ethanol-induced cardiomyocyte contractile dysfunction, apoptosis and autophagy. In summary, these findings suggested that ALDH2 elicits cardioprotection against chronic alcohol intake-induced cardiac geometric and functional anomalies by inhibition of autophagy possibly via restoring the Akt-mTOR-STAT3-Notch signalling cascade. PMID:21609394

  1. miR-124 regulates cell apoptosis and autophagy in dopaminergic neurons and protects them by regulating AMPK/mTOR pathway in Parkinson’s disease

    PubMed Central

    Gong, Xin; Wang, Huiqing; Ye, Yongyi; Shu, Yugao; Deng, Yongwen; He, Xiaozheng; Lu, Guohui; Zhang, Shizhong

    2016-01-01

    The important roles of miR-124 in the development and progression of various diseases are being increasing recognized. This study was aimed to investigate the potential roles of miR-124 in dopaminergic (DA) neuronal apoptosis and autophagy in Parkinson’s disease (PD) and to explore their mechanisms. Human SH-SY5Y cells that are treated with MPTP were transfected with mature miR-124 vector and control empty vector. The effect of MPTP on miR-124 mRNA level was analyzed using RT-PCR analysis. Furthermore, the effects of miR-124 expression on neuronal apoptosis and autophagy, as well as the expression of proteins in the AMPK/mTOR pathway, were analyzed using RT-PCR and western blotting. This study found that miR-124 was down-regulated in the MPTP-treated (100 μM) neurons, and miR-124 suppression significantly increased cell apoptosis and induced autophagy-associated protein expression, including that of Beclin 1 and increased the ratio of LC3 II/LC3 I compared with that in controls. In addition, in vitro rescue of miR-124 significantly decreased the percentage of apoptotic cells and the ratio of LC3 II/LC3 I, findings that were approximately equal to the controls. Moreover, miR-124 suppression increased p-AMPK but decreased p-mTOR levels in neurons. Our study suggested that miR-124 functions as a protector of DA neurons during PD through the involvement of cell apoptosis and autophagy by regulating the AMPK/mTOR pathway. PMID:27347320

  2. Parkinson's Disease and Autophagy

    PubMed Central

    Sánchez-Pérez, Ana María; Claramonte-Clausell, Berta; Sánchez-Andrés, Juan Vicente; Herrero, María Trinidad

    2012-01-01

    It is generally accepted that a correlation between neurodegenerative disease and protein aggregation in the brain exists; however, a causal relationship has not been elucidated. In neurons, failure of autophagy may result in the accumulation of aggregate-prone proteins and subsequent neurodegeneration. Thus, pharmacological induction of autophagy to enhance the clearance of intracytoplasmic aggregate-prone proteins has been considered as a therapeutic strategy to ameliorate pathology in cell and animal models of neurodegenerative disorders. However, autophagy has also been found to be a factor in the onset of these diseases, which raises the question of whether autophagy induction is an effective therapeutic strategy, or, on the contrary, can result in cell death. In this paper, we will first describe the autophagic machinery, and we will consider the literature to discuss the neuroprotective effects of autophagy. PMID:23125941

  3. Protective effect of fucoidan from Fucus vesiculosus on liver fibrosis via the TGF-β1/Smad pathway-mediated inhibition of extracellular matrix and autophagy

    PubMed Central

    Li, Jingjing; Chen, Kan; Li, Sainan; Feng, Jiao; Liu, Tong; Wang, Fan; Zhang, Rong; Xu, Shizan; Zhou, Yuqing; Zhou, Shunfeng; Xia, Yujing; Lu, Jie; Zhou, Yingqun; Guo, Chuanyong

    2016-01-01

    Liver fibrosis is a dynamic reversible pathological process in the development of chronic liver disease to cirrhosis. However, the current treatments are not administered for a long term due to their various side effects. Autophagy is initiated to decompose damaged or excess organelles, which had been found to alter the progression of liver fibrosis. In this article, we hypothesized that fucoidan from Fucus vesiculosus may attenuate liver fibrosis in mice by inhibition of the extracellular matrix and autophagy in carbon tetrachloride- and bile duct ligation-induced animal models of liver fibrosis. The results were determined using enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemical staining. Fucoidan from F. vesiculosus could inhibit the activation of hepatic stellate cells and the formation of extracellular matrix and autophagosomes, and its effect may be associated with the downregulation of transforming growth factor beta 1/Smads pathways. Fucoidan, as an autophagy and transforming growth factor beta 1 inhibitor, could be a promising potential therapeutic agent for liver fibrosis. PMID:26929597

  4. Crystal Structure of Oxidative Stress Sensor Keap1 in Complex with Selective Autophagy Substrate p62

    NASA Astrophysics Data System (ADS)

    Kurokawa, Hirofumi

    Keap1, an adaptor protein of cullin-RING ubiquitin ligase complex, represses cytoprotective transcription factor Nrf2 in an oxidative stress-dependent manner. The accumulation of selective autophagy substrate p62 also activates Nrf2 target genes, but the detailed mechanism has not been elucidated. Crystal structure of Keap1-p62 complex revealed the structural basis for the Nrf2 activation in which Keap1 is inactivated by p62. The accumulation of p62 is observed in hepatocellular carcinoma. The activation of Nrf2 target genes, including detoxifying enzymes and efflux transporters, by p62 may protect the cancer cells from anti-cancer drugs.

  5. Microgravity control of autophagy modulates osteoclastogenesis.

    PubMed

    Sambandam, Yuvaraj; Townsend, Molly T; Pierce, Jason J; Lipman, Cecilia M; Haque, Azizul; Bateman, Ted A; Reddy, Sakamuri V

    2014-04-01

    Evidence indicates that astronauts experience significant bone loss during space mission. Recently, we used the NASA developed rotary cell culture system (RCCS) to simulate microgravity (μXg) conditions and demonstrated increased osteoclastogenesis in mouse bone marrow cultures. Autophagy is a cellular recycling process of nutrients. Therefore, we hypothesize that μXg control of autophagy modulates osteoclastogenesis. Real-time PCR analysis of total RNA isolated from mouse bone marrow derived non-adherent cells subjected to modeled μXg showed a significant increase in autophagic marker Atg5, LC3 and Atg16L mRNA expression compared to ground based control (Xg) cultures. Western blot analysis of total cell lysates identified an 8.0-fold and 7.0-fold increase in the Atg5 and LC3-II expression, respectively. Confocal microscopy demonstrated an increased autophagosome formation in μXg subjected RAW 264.7 preosteoclast cells. RT(2) profiler PCR array screening for autophagy related genes identified that μXg upregulates intracellular signaling molecules associated with autophagy, autophagosome components and inflammatory cytokines/growth factors which coregulate autophagy in RAW 264.7 preosteoclast cells. Autophagy inhibitor, 3-methyladenine (3-MA) treatment of mouse bone marrow derived non-adherent mononuclear cells showed a significant decrease in μXg induced Atg5 and LC3 mRNA expression in the presence or absence of RANK ligand (RANKL) stimulation. Furthermore, RANKL treatment significantly increased (8-fold) p-CREB transcription factor levels under μXg as compared to Xg cultures and 3-MA inhibited RANKL increased p-CREB expression in these cells. Also, 3-MA suppresses μXg elevated osteoclast differentiation in mouse bone marrow cultures. Thus, our results suggest that μXg induced autophagy plays an important role in enhanced osteoclast differentiation and could be a potential therapeutic target to prevent bone loss in astronauts during space flight missions

  6. Microgravity control of autophagy modulates osteoclastogenesis

    PubMed Central

    Sambandam, Yuvaraj; Townsend, Molly T.; Pierce, Jason J.; Lipman, Cecilia M.; Haque, Azizul; Bateman, Ted A.; Reddy, Sakamuri V.

    2015-01-01

    Evidence indicates that astronauts experience significant bone loss during space mission. Recently, we used the NASA developed rotary cell culture system (RCCS) to simulate microgravity (μXg) conditions and demonstrated increased osteoclastogenesis in mouse bone marrow cultures. Autophagy is a cellular recycling process of nutrients. Therefore, we hypothesize that μXg control of autophagy modulates osteoclastogenesis. Real-time PCR analysis of total RNA isolated from mouse bone marrow derived non-adherent cells subjected to modeled μXg showed a significant increase in autophagic marker Atg5, LC3 and Atg16L mRNA expression compared to ground based control (Xg) cultures. Western blot analysis of total cell lysates identified an 8.0-fold and 7.0-fold increase in the Atg5 and LC3-II expression, respectively. Confocal microscopy demonstrated an increased autophagosome formation in μXg subjected RAW 264.7 preosteoclast cells. RT2 profiler PCR array screening for autophagy related genes identified that μXg upregulates intracellular signaling molecules associated with autophagy, autophagosome components and inflammatory cytokines/growth factors which coregulate autophagy in RAW 264.7 preosteoclast cells. Autophagy inhibitor, 3-methyladenine (3-MA) treatment of mouse bone marrow derived non-adherent mononuclear cells showed a significant decrease in μXg induced Atg5 and LC3 mRNA expression in the presence or absence of RANK ligand (RANKL) stimulation. Furthermore, RANKL treatment significantly increased (8-fold) p-CREB transcription factor levels under μXg as compared to Xg cultures and 3-MA inhibited RANKL increased p-CREB expression in these cells. Also, 3-MA suppresses μXg elevated osteoclast differentiation in mouse bone marrow cultures. Thus, our results suggest that μXg induced autophagy plays an important role in enhanced osteoclast differentiation and could be a potential therapeutic target to prevent bone loss in astronauts during space flight missions

  7. WIPI-Mediated Autophagy and Longevity

    PubMed Central

    Grimmel, Mona; Backhaus, Charlotte; Proikas-Cezanne, Tassula

    2015-01-01

    Autophagy is a lysosomal degradation process for cytoplasmic components, including organelles, membranes, and proteins, and critically secures eukaryotic cellular homeostasis and survival. Moreover, autophagy-related (ATG) genes are considered essential for longevity control in model organisms. Central to the regulatory relationship between autophagy and longevity is the control of insulin/insulin-like growth factor receptor-driven activation of mTOR (mechanistic target of rapamycin), which inhibits WIPI (WD repeat protein interacting with phosphoinositides)-mediated autophagosome formation. Release of the inhibitory mTOR action on autophagy permits the production of PI3P (phosphatidylinositol-3 phosphate), predominantly at the endoplasmic reticulum, to function as an initiation signal for the formation of autophagosomes. WIPI proteins detect this pool of newly produced PI3P and function as essential PI3P effector proteins that recruit downstream autophagy-related (ATG) proteins. The important role of WIPI proteins in autophagy is highlighted by functional knockout of the WIPI homologues ATG-18 and EPG-6 in Caenorhabditis elegans (C. elegans). Adult lifespan is significantly reduced in ATG-18 mutant animals, demonstrating that longevity as such is crucially determined by essential autophagy factors. In this review we summarize the role of WIPI proteins and their C. elegans homologues with regard to the molecular basis of aging. As the development of strategies on how to increase health span in humans is increasingly appreciated, we speculate that targeting WIPI protein function might represent a therapeutic opportunity to fight and delay the onset of age-related human diseases. PMID:26010754

  8. Depletion of autophagy receptor p62/SQSTM1 enhances the efficiency of gene delivery in mammalian cells.

    PubMed

    Tsuchiya, Megumi; Ogawa, Hidesato; Koujin, Takako; Kobayashi, Shouhei; Mori, Chie; Hiraoka, Yasushi; Haraguchi, Tokuko

    2016-08-01

    Novel methods that increase the efficiency of gene delivery to cells will have many useful applications. Here, we report a simple approach involving depletion of p62/SQSTM1 to enhance the efficiency of gene delivery. The efficiency of reporter gene delivery was remarkably higher in p62-knockout murine embryonic fibroblast (MEF) cells compared with normal MEF cells. This higher efficiency was partially attenuated by ectopic expression of p62. Furthermore, siRNA-mediated knockdown of p62 clearly increased the efficiency of transfection of murine embryonic stem (mES) cells and human HeLa cells. These data indicate that p62 acts as a key regulator of gene delivery. PMID:27317902

  9. Autophagy in Drosophila: From Historical Studies to Current Knowledge

    PubMed Central

    Mulakkal, Nitha C.; Nagy, Peter; Takats, Szabolcs; Tusco, Radu; Juhász, Gábor; Nezis, Ioannis P.

    2014-01-01

    The discovery of evolutionarily conserved Atg genes required for autophagy in yeast truly revolutionized this research field and made it possible to carry out functional studies on model organisms. Insects including Drosophila are classical and still popular models to study autophagy, starting from the 1960s. This review aims to summarize past achievements and our current knowledge about the role and regulation of autophagy in Drosophila, with an outlook to yeast and mammals. The basic mechanisms of autophagy in fruit fly cells appear to be quite similar to other eukaryotes, and the role that this lysosomal self-degradation process plays in Drosophila models of various diseases already made it possible to recognize certain aspects of human pathologies. Future studies in this complete animal hold great promise for the better understanding of such processes and may also help finding new research avenues for the treatment of disorders with misregulated autophagy. PMID:24949430

  10. The Emerging Importance of Autophagy in Pulmonary Diseases

    PubMed Central

    Mizumura, Kenji; Cloonan, Suzanne M.; Haspel, Jeffrey A.

    2012-01-01

    Important cellular processes such as inflammation, apoptosis, differentiation, and proliferation confer critical roles in the pathogenesis of human diseases. In the past decade, an emerging process named “autophagy” has generated intense interest in both biomedical research and clinical medicine. Autophagy is a regulated cellular pathway for the turnover of organelles and proteins by lysosomal-dependent processing. Although autophagy was once considered a bulk degradation event, research shows that autophagy selectively degrades specific proteins, organelles, and invading bacteria, a process termed “selective autophagy.” It is increasingly clear that autophagy is directly relevant to clinical disease, including pulmonary disease. This review outlines the principal components of the autophagic process and discusses the importance of autophagy and autophagic proteins in pulmonary diseases from COPD, α1-antitrypsin deficiency, pulmonary hypertension, acute lung injury, and cystic fibrosis to respiratory infection and sepsis. Finally, we examine the dual nature of autophagy in the lung, which has both protective and deleterious effects resulting from adaptive and maladaptive responses, and the challenge this duality poses for designing autophagy-based diagnostic and therapeutic targets in lung disease. PMID:23131937

  11. Autophagy: a new target for nonalcoholic fatty liver disease therapy.

    PubMed

    Mao, Yuqing; Yu, Fujun; Wang, Jianbo; Guo, Chuanyong; Fan, Xiaoming

    2016-01-01

    Nonalcoholic fatty liver disease (NAFLD) has gained importance in recent decades due to drastic changes in diet, especially in Western countries. NAFLD occurs as a spectrum from simple hepatic steatosis, steatohepatitis to cirrhosis, and even hepatocellular carcinoma. Although the molecular mechanisms underlying the development of NAFLD have been intensively investigated, many issues remain to be resolved. Autophagy is a cell survival mechanism for disposing of excess or defective organelles, and has become a hot spot for research. Recent studies have revealed that autophagy is linked to the development of NAFLD and regulation of autophagy has therapeutic potential. Autophagy reduces intracellular lipid droplets by enclosing them and fusing with lysosomes for degradation. Furthermore, autophagy is involved in attenuating inflammation and liver injury. However, autophagy is regarded as a double-edged sword, as it may also affect adipogenesis and adipocyte differentiation. Moreover, it is unclear as to whether autophagy protects the body from injury or causes diseases and even death, and the association between autophagy and NAFLD remains controversial. This review is intended to discuss, comment, and outline the progress made in this field and establish the possible molecular mechanism involved. PMID:27099536

  12. Autophagy: a new target for nonalcoholic fatty liver disease therapy

    PubMed Central

    Mao, Yuqing; Yu, Fujun; Wang, Jianbo; Guo, Chuanyong; Fan, Xiaoming

    2016-01-01

    Nonalcoholic fatty liver disease (NAFLD) has gained importance in recent decades due to drastic changes in diet, especially in Western countries. NAFLD occurs as a spectrum from simple hepatic steatosis, steatohepatitis to cirrhosis, and even hepatocellular carcinoma. Although the molecular mechanisms underlying the development of NAFLD have been intensively investigated, many issues remain to be resolved. Autophagy is a cell survival mechanism for disposing of excess or defective organelles, and has become a hot spot for research. Recent studies have revealed that autophagy is linked to the development of NAFLD and regulation of autophagy has therapeutic potential. Autophagy reduces intracellular lipid droplets by enclosing them and fusing with lysosomes for degradation. Furthermore, autophagy is involved in attenuating inflammation and liver injury. However, autophagy is regarded as a double-edged sword, as it may also affect adipogenesis and adipocyte differentiation. Moreover, it is unclear as to whether autophagy protects the body from injury or causes diseases and even death, and the association between autophagy and NAFLD remains controversial. This review is intended to discuss, comment, and outline the progress made in this field and establish the possible molecular mechanism involved. PMID:27099536

  13. Cellular and Molecular Connections between Autophagy and Inflammation

    PubMed Central

    Lapaquette, Pierre; Guzzo, Jean; Bretillon, Lionel; Bringer, Marie-Agnès

    2015-01-01

    Autophagy is an intracellular catabolic pathway essential for the recycling of proteins and larger substrates such as aggregates, apoptotic corpses, or long-lived and superfluous organelles whose accumulation could be toxic for cells. Because of its unique feature to engulf part of cytoplasm in double-membrane cup-shaped structures, which further fuses with lysosomes, autophagy is also involved in the elimination of host cell invaders and takes an active part of the innate and adaptive immune response. Its pivotal role in maintenance of the inflammatory balance makes dysfunctions of the autophagy process having important pathological consequences. Indeed, defects in autophagy are associated with a wide range of human diseases including metabolic disorders (diabetes and obesity), inflammatory bowel disease (IBD), and cancer. In this review, we will focus on interrelations that exist between inflammation and autophagy. We will discuss in particular how mediators of inflammation can regulate autophagy activity and, conversely, how autophagy shapes the inflammatory response. Impact of genetic polymorphisms in autophagy-related gene on inflammatory bowel disease will be also discussed. PMID:26221063

  14. Autophagy in protists

    PubMed Central

    Duszenko, Michael; Ginger, Michael L; Brennand, Ana; Gualdrón-López, Melisa; Colombo, Maria-Isabel; Coombs, Graham H; Coppens, Isabelle; Jayabalasingham, Bamini; Langsley, Gordon; de Castro, Solange Lisboa; Menna-Barreto, Rubem; Mottram, Jeremy C; Navarro, Miguel; Rigden, Daniel J; Romano, Patricia S; Stoka, Veronika; Turk, Boris

    2011-01-01

    Autophagy is the degradative process by which eukaryotic cells digest their own components using acid hydrolases within the lysosome. Originally thought to function almost exclusively in providing starving cells with nutrients taken from their own cellular constituents, autophagy is in fact involved in numerous cellular events including differentiation, turnover of macromolecules and organelles and defense against parasitic invaders. During the past 10–20 years, molecular components of the autophagic machinery have been discovered, revealing a complex interactome of proteins and lipids, which, in a concerted way, induce membrane formation to engulf cellular material and target it for lysosomal degradation. Here, our emphasis is autophagy in protists. We discuss experimental and genomic data indicating that the canonical autophagy machinery characterized in animals and fungi appeared prior to the radiation of major eukaryotic lineages. Moreover, we describe how comparative bioinformatics revealed that this canonical machinery has been subject to moderation, outright loss or elaboration on multiple occasions in protist lineages, most probably as a consequence of diverse lifestyle adaptations. We also review experimental studies illustrating how several pathogenic protists either utilize autophagy mechanisms or manipulate host-cell autophagy in order to establish or maintain infection within a host. The essentiality of autophagy for the pathogenicity of many parasites, and the unique features of some of the autophagy-related proteins involved, suggest possible new targets for drug discovery. Further studies of the molecular details of autophagy in protists will undoubtedly enhance our understanding of the diversity and complexity of this cellular phenomenon and the opportunities it offers as a drug target. PMID:20962583

  15. Autophagy in protists.

    PubMed

    Duszenko, Michael; Ginger, Michael L; Brennand, Ana; Gualdrón-López, Melisa; Colombo, María Isabel; Coombs, Graham H; Coppens, Isabelle; Jayabalasingham, Bamini; Langsley, Gordon; de Castro, Solange Lisboa; Menna-Barreto, Rubem; Mottram, Jeremy C; Navarro, Miguel; Rigden, Daniel J; Romano, Patricia S; Stoka, Veronika; Turk, Boris; Michels, Paul A M

    2011-02-01

    Autophagy is the degradative process by which eukaryotic cells digest their own components using acid hydrolases within the lysosome. Originally thought to function almost exclusively in providing starving cells with nutrients taken from their own cellular constituents, autophagy is in fact involved in numerous cellular events including differentiation, turnover of macromolecules and organelles, and defense against parasitic invaders. During the last 10-20 years, molecular components of the autophagic machinery have been discovered, revealing a complex interactome of proteins and lipids, which, in a concerted way, induce membrane formation to engulf cellular material and target it for lysosomal degradation. Here, our emphasis is autophagy in protists. We discuss experimental and genomic data indicating that the canonical autophagy machinery characterized in animals and fungi appeared prior to the radiation of major eukaryotic lineages. Moreover, we describe how comparative bioinformatics revealed that this canonical machinery has been subject to moderation, outright loss or elaboration on multiple occasions in protist lineages, most probably as a consequence of diverse lifestyle adaptations. We also review experimental studies illustrating how several pathogenic protists either utilize autophagy mechanisms or manipulate host-cell autophagy in order to establish or maintain infection within a host. The essentiality of autophagy for the pathogenicity of many parasites, and the unique features of some of the autophagy-related proteins involved, suggest possible new targets for drug discovery. Further studies of the molecular details of autophagy in protists will undoubtedly enhance our understanding of the diversity and complexity of this cellular phenomenon and the opportunities it offers as a drug target. PMID:20962583

  16. Ambra1 in autophagy and apoptosis: Implications for cell survival and chemotherapy resistance

    PubMed Central

    SUN, WEI-LIANG

    2016-01-01

    Increasing studies suggest that autophagy has a protective role in cancer treatment and may even be involved in chemotherapy resistance. Nevertheless, the mechanism of autophagy in cancer treatment and drug resistance has not yet been established. There is a complex association between autophagy and apoptosis. Accordingly, these two processes can mutually regulate and transform to determine the fate of a cell, depending on the context. Activating molecule in Beclin 1-regulated autophagy protein 1 (Ambra1) is an important factor at the crossroad between autophagy and apoptosis. The expression level and intracellular distributions of Ambra1 may control the balance and conversion between autophagy and apoptosis, and modify the effectiveness of chemotherapy. Therefore, Ambra1 may provide a novel target for cancer treatment, particularly for overcoming anticancer drug resistance. The present review focuses on the role of Ambra1 in autophagy and apoptosis and assesses the implications for cell survival and chemotherapy resistance. PMID:27347152

  17. Autophagy and neurodegeneration

    PubMed Central

    Frake, Rebecca A.; Ricketts, Thomas; Menzies, Fiona M.; Rubinsztein, David C.

    2015-01-01

    Most neurodegenerative diseases that afflict humans are associated with the intracytoplasmic deposition of aggregate-prone proteins in neurons. Autophagy is a powerful process for removing such proteins. In this Review, we consider how certain neurodegenerative diseases may be associated with impaired autophagy and how this may affect pathology. We also discuss how autophagy induction may be a plausible therapeutic strategy for some conditions and review studies in various models that support this hypothesis. Finally, we briefly describe some of the signaling pathways that may be amenable to therapeutic targeting for these goals. PMID:25654552

  18. IL-1 receptor blockade restores autophagy and reduces inflammation in chronic granulomatous disease in mice and in humans.

    PubMed

    de Luca, Antonella; Smeekens, Sanne P; Casagrande, Andrea; Iannitti, Rossana; Conway, Kara L; Gresnigt, Mark S; Begun, Jakob; Plantinga, Theo S; Joosten, Leo A B; van der Meer, Jos W M; Chamilos, Georgios; Netea, Mihai G; Xavier, Ramnik J; Dinarello, Charles A; Romani, Luigina; van de Veerdonk, Frank L

    2014-03-01

    Patients with chronic granulomatous disease (CGD) have a mutated NADPH complex resulting in defective production of reactive oxygen species; these patients can develop severe colitis and are highly susceptible to invasive fungal infection. In NADPH oxidase-deficient mice, autophagy is defective but inflammasome activation is present despite lack of reactive oxygen species production. However, whether these processes are mutually regulated in CGD and whether defective autophagy is clinically relevant in patients with CGD is unknown. Here, we demonstrate that macrophages from CGD mice and blood monocytes from CGD patients display minimal recruitment of microtubule-associated protein 1 light chain 3 (LC3) to phagosomes. This defect in autophagy results in increased IL-1β release. Blocking IL-1 with the receptor antagonist (anakinra) decreases neutrophil recruitment and T helper 17 responses and protects CGD mice from colitis and also from invasive aspergillosis. In addition to decreased inflammasome activation, anakinra restored autophagy in CGD mice in vivo, with increased Aspergillus-induced LC3 recruitment and increased expression of autophagy genes. Anakinra also increased Aspergillus-induced LC3 recruitment from 23% to 51% (P < 0.01) in vitro in monocytes from CGD patients. The clinical relevance of these findings was assessed by treating CGD patients who had severe colitis with IL-1 receptor blockade using anakinra. Anakinra treatment resulted in a rapid and sustained improvement in colitis. Thus, inflammation in CGD is due to IL-1-dependent mechanisms, such as decreased autophagy and increased inflammasome activation, which are linked pathological conditions in CGD that can be restored by IL-1 receptor blockade. PMID:24550444

  19. Boning up on autophagy

    PubMed Central

    Shapiro, Irving M; Layfield, Robert; Lotz, Martin; Settembre, Carmine; Whitehouse, Caroline

    2014-01-01

    From an evolutionary perspective, the major function of bone is to provide stable sites for muscle attachment and affording protection of vital organs, especially the heart and lungs (ribs) and spinal cord (vertebrae and intervertebral discs). However, bone has a considerable number of other functions: serving as a store for mineral ions, providing a site for blood cell synthesis and participating in a complex system-wide endocrine system. Not surprisingly, bone and cartilage cell homeostasis is tightly controlled, as is the maintenance of tissue structure and mass. While a great deal of new information is accruing concerning skeletal cell homeostasis, one relatively new observation is that the cells of bone (osteoclasts osteoblasts and osteocytes) and cartilage (chondrocytes) exhibit autophagy. The focus of this review is to examine the significance of this process in terms of the functional demands of the skeleton in health and during growth and to provide evidence that dysregulation of the autophagic response is involved in the pathogenesis of diseases of bone (Paget disease of bone) and cartilage (osteoarthritis and the mucopolysaccharidoses). Delineation of molecular changes in the autophagic process is uncovering new approaches for the treatment of diseases that affect the axial and appendicular skeleton. PMID:24225636

  20. Protection of expressed immunoglobulin genes against nuclease cleavage.

    PubMed Central

    Weischet, W O; Glotov, B O; Zachau, H G

    1983-01-01

    Fragmentation of the actively transcribed kappa immunoglobulin gene in mouse myeloma nuclei with micrococcal nuclease and the restriction nuclease Bsp RI reveals a chromatin structure without the regularity of repeating nucleosomes found in bulk chromatin. Such regularity is restored about 2.2 kb 3' of the coding region. An only moderately increased micrococcal nuclease sensitivity and a 65% average protection of the Bsp RI sites indicates a DNA-protein interaction in the transcribed region which is not very different from that of an inactive gene. As determined by indirect endlabeling the frequency of Bsp RI cleavage both, after very mild and exhaustive digestion, varied moderately from site to site along the gene. In addition, it was not in each case the same at analogous sites on both alleles which are both transcribed. Thus, the experiments demonstrate differences between the chromatin structures of the genes which may be related to regulatory phenomena and thereby corroborate earlier findings made with DNAase I. Images PMID:6304636

  1. Proper autophagy is indispensable for angiogenesis during chick embryo development.

    PubMed

    Lu, Wen-Hui; Shi, Yu-Xun; Ma, Zheng-Lai; Wang, Guang; Liu, Langxia; Chuai, Manli; Song, Xiaoyu; Münsterberg, Andrea; Cao, Liu; Yang, Xuesong

    2016-07-01

    People have known that autophagy plays a very important role in many physiological and pathological events. But the role of autophagy on embryonic angiogenesis still remains obscure. In this study, we demonstrated that Atg7, Atg8 and Beclin1 were expressed in the plexus vessels of angiogenesis at chick yolk sac membrane and chorioallantoic membrane. Interfering in autophagy with autophagy inducer or inhibitor could restrict the angiogenesis in vivo, which might be driven by the disorder of angiogenesis-related gene expressions, and also lead to embryonic hemorrhage, which was due to imperfection cell junctions in endothelial cells including abnormal expressions of tight junction, adheren junction and desmosome genes. Using HUVECs, we revealed that cell viability and migration ability changed with the alteration of cell autophagy exposed to RAPA or 3-MA. Interestingly, tube formation assay showed that HUVECs ability of tube formation altered with the change of Atg5, Atg7 and Atg8 manipulated by the transfection of their corresponding siRNA or plasmids. Moreover, the lost cell polarity labeled by F-actin and the absenced β-catenin in RAPA-treated and 3-MA-treated cell membrane implied intracellular cytoskeleton alteration was induced by the activation and depression of autophagy. Taken together, our current experimental data reveal that autophagy is really involved in regulating angiogenesis during embryo development. PMID:27163719

  2. Lithium and autophagy.

    PubMed

    Motoi, Yumiko; Shimada, Kohei; Ishiguro, Koichi; Hattori, Nobutaka

    2014-06-18

    Lithium, a drug used to treat bipolar disorders, has a variety of neuroprotective mechanisms, including autophagy regulation, in various neuropsychiatric conditions. In neurodegenerative diseases, lithium enhances degradation of aggregate-prone proteins, including mutated huntingtin, phosphorylated tau, and α-synuclein, and causes damaged mitochondria to degrade, while in a mouse model of cerebral ischemia and Alzheimer's disease autophagy downregulation by lithium is observed. The signaling pathway of lithium as an autophagy enhancer might be associated with the mammalian target of rapamycin (mTOR)-independent pathway, which is involved in myo-inositol-1,4,5-trisphosphate (IP3) in Huntington's disease and Parkinson's disease. However, the mTOR-dependent pathway might be involved in inhibiting glycogen synthase kinase-3β (GSK3β) in other diseases. Lithium's autophagy-enhancing property may contribute to the therapeutic benefit of patients with neuropsychiatric disorders. PMID:24738557

  3. DAMPs and autophagy

    PubMed Central

    Zhang, Qiuhong; Kang, Rui; Zeh, III, Herbert J.; Lotze, Michael T.; Tang, Daolin

    2013-01-01

    Autophagy is a lysosome-mediated catabolic process involving the degradation of intracellular contents (e.g., proteins and organelles) as well as invading microbes (e.g., parasites, bacteria and viruses). Multiple forms of cellular stress can stimulate this pathway, including nutritional imbalances, oxygen deprivation, immunological response, genetic defects, chromosomal anomalies and cytotoxic stress. Damage-associated molecular pattern molecules (DAMPs) are released by stressed cells undergoing autophagy or injury, and act as endogenous danger signals to regulate the subsequent inflammatory and immune response. A complex relationship exists between DAMPs and autophagy in cellular adaption to injury and unscheduled cell death. Since both autophagy and DAMPs are important for pathogenesis of human disease, it is crucial to understand how they interplay to sustain homeostasis in stressful or dangerous environments. PMID:23388380

  4. Amino acid metabolism inhibits antibody-driven kidney injury by inducing autophagy.

    PubMed

    Chaudhary, Kapil; Shinde, Rahul; Liu, Haiyun; Gnana-Prakasam, Jaya P; Veeranan-Karmegam, Rajalakshmi; Huang, Lei; Ravishankar, Buvana; Bradley, Jillian; Kvirkvelia, Nino; McMenamin, Malgorzata; Xiao, Wei; Kleven, Daniel; Mellor, Andrew L; Madaio, Michael P; McGaha, Tracy L

    2015-06-15

    Inflammatory kidney disease is a major clinical problem that can result in end-stage renal failure. In this article, we show that Ab-mediated inflammatory kidney injury and renal disease in a mouse nephrotoxic serum nephritis model was inhibited by amino acid metabolism and a protective autophagic response. The metabolic signal was driven by IFN-γ-mediated induction of indoleamine 2,3-dioxygenase 1 (IDO1) enzyme activity with subsequent activation of a stress response dependent on the eIF2α kinase general control nonderepressible 2 (GCN2). Activation of GCN2 suppressed proinflammatory cytokine production in glomeruli and reduced macrophage recruitment to the kidney during the incipient stage of Ab-induced glomerular inflammation. Further, inhibition of autophagy or genetic ablation of Ido1 or Gcn2 converted Ab-induced, self-limiting nephritis to fatal end-stage renal disease. Conversely, increasing kidney IDO1 activity or treating mice with a GCN2 agonist induced autophagy and protected mice from nephritic kidney damage. Finally, kidney tissue from patients with Ab-driven nephropathy showed increased IDO1 abundance and stress gene expression. Thus, these findings support the hypothesis that the IDO-GCN2 pathway in glomerular stromal cells is a critical negative feedback mechanism that limits inflammatory renal pathologic changes by inducing autophagy. PMID:25980011

  5. Induction of Protective Genes Leads to Islet Survival and Function

    PubMed Central

    Wang, Hongjun; Ferran, Christiane; Attanasio, Chiara; Calise, Fulvio; Otterbein, Leo E.

    2011-01-01

    Islet transplantation is the most valid approach to the treatment of type 1 diabetes. However, the function of transplanted islets is often compromised since a large number of β cells undergo apoptosis induced by stress and the immune rejection response elicited by the recipient after transplantation. Conventional treatment for islet transplantation is to administer immunosuppressive drugs to the recipient to suppress the immune rejection response mounted against transplanted islets. Induction of protective genes in the recipient (e.g., heme oxygenase-1 (HO-1), A20/tumor necrosis factor alpha inducible protein3 (tnfaip3), biliverdin reductase (BVR), Bcl2, and others) or administration of one or more of the products of HO-1 to the donor, the islets themselves, and/or the recipient offers an alternative or synergistic approach to improve islet graft survival and function. In this perspective, we summarize studies describing the protective effects of these genes on islet survival and function in rodent allogeneic and xenogeneic transplantation models and the prevention of onset of diabetes, with emphasis on HO-1, A20, and BVR. Such approaches are also appealing to islet autotransplantation in patients with chronic pancreatitis after total pancreatectomy, a procedure that currently only leads to 1/3 of transplanted patients being diabetes-free. PMID:22220267

  6. PINK1 deficiency enhances autophagy and mitophagy induction

    PubMed Central

    Gómez-Sánchez, Rubén; Yakhine-Diop, Sokhna M S; Bravo-San Pedro, José M; Pizarro-Estrella, Elisa; Rodríguez-Arribas, Mario; Climent, Vicente; Martin-Cano, Francisco E; González-Soltero, María E; Tandon, Anurag; Fuentes, José M; González-Polo, Rosa A

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder with poorly understood etiology. Increasing evidence suggests that age-dependent compromise of the maintenance of mitochondrial function is a key risk factor. Several proteins encoded by PD-related genes are associated with mitochondria including PTEN-induced putative kinase 1 (PINK1), which was first identified as a gene that is upregulated by PTEN. Loss-of-function PINK1 mutations induce mitochondrial dysfunction and, ultimately, neuronal cell death. To mitigate the negative effects of altered cellular functions cells possess a degradation mechanism called autophagy for recycling damaged components; selective elimination of dysfunctional mitochondria by autophagy is termed mitophagy. Our study indicates that autophagy and mitophagy are upregulated in PINK1-deficient cells, and is the first report to demonstrate efficient fluxes by one-step analysis. We propose that autophagy is induced to maintain cellular homeostasis under conditions of non-regulated mitochondrial quality control. PMID:27308585

  7. PINK1 deficiency enhances autophagy and mitophagy induction.

    PubMed

    Gómez-Sánchez, Rubén; Yakhine-Diop, Sokhna M S; Bravo-San Pedro, José M; Pizarro-Estrella, Elisa; Rodríguez-Arribas, Mario; Climent, Vicente; Martin-Cano, Francisco E; González-Soltero, María E; Tandon, Anurag; Fuentes, José M; González-Polo, Rosa A

    2016-03-01

    Parkinson's disease (PD) is a neurodegenerative disorder with poorly understood etiology. Increasing evidence suggests that age-dependent compromise of the maintenance of mitochondrial function is a key risk factor. Several proteins encoded by PD-related genes are associated with mitochondria including PTEN-induced putative kinase 1 (PINK1), which was first identified as a gene that is upregulated by PTEN. Loss-of-function PINK1 mutations induce mitochondrial dysfunction and, ultimately, neuronal cell death. To mitigate the negative effects of altered cellular functions cells possess a degradation mechanism called autophagy for recycling damaged components; selective elimination of dysfunctional mitochondria by autophagy is termed mitophagy. Our study indicates that autophagy and mitophagy are upregulated in PINK1-deficient cells, and is the first report to demonstrate efficient fluxes by one-step analysis. We propose that autophagy is induced to maintain cellular homeostasis under conditions of non-regulated mitochondrial quality control. PMID:27308585

  8. Autophagy and checkpoints for intracellular pathogen defense

    PubMed Central

    Paulus, Geraldine L.C.; Xavier, Ramnik J.

    2015-01-01

    Purpose of review Autophagy plays a crucial role in intracellular defense against various pathogens. Xenophagy is a form of selective autophagy that targets intracellular pathogens for degradation. In addition, several related yet distinct intracellular defense responses depend on autophagy-related (ATG) genes. This review gives an overview of these processes, pathogen strategies to subvert them, and their crosstalk with various cell death programs. Recent findings The recruitment of ATG proteins plays a key role in multiple intracellular defense programs, specifically xenophagy, LC3-associated phagocytosis (LAP), and the IFNγ-mediated elimination of pathogens such as Toxoplasma gondii and murine norovirus. Recent progress has revealed methods employed by pathogens to resist these intracellular defense mechanisms and/or persist in spite of them. The intracellular pathogen load can tip the balance between cell survival and cell death. Further, it was recently observed that LAP is indispensable for the efficient clearance of dying cells. Summary Autophagy-dependent and ATG gene-dependent pathways are essential in intracellular defense against a broad range of pathogens. PMID:25394238

  9. The autophagy-related genes BbATG1 and BbATG8 have different functions in differentiation, stress resistance and virulence of mycopathogen Beauveria bassiana

    PubMed Central

    Ying, Sheng-Hua; Liu, Jing; Chu, Xin-Ling; Xie, Xue-Qin; Feng, Ming-Guang

    2016-01-01

    Autophagy-related proteins play significantly different roles in eukaryotes. In the entomopathogenic fungus Beauveria bassiana, autophagy is associated with fungal growth and development. BbATG1 (a serine/threonine protein kinase) and BbATG8 (a ubiquitin-like protein) have similar roles in autophagy, but different roles in other processes. Disruption mutants of BbATG1 and BbATG8 had impaired conidial germination under starvation stress. The mutant ΔBbATG8 exhibited enhanced sensitivity to oxidative stress, while a ΔBbATG1 mutant did not. BbATG1 and BbATG8 showed different roles in spore differentiation. The blastospore yield was reduced by 70% and 92% in ΔBbATG1 and ΔBbATG8 mutants, respectively, and the double mutant had a reduction of 95%. Conidial yield was reduced by approximately 90% and 50% in ΔBbATG1 and ΔBbATG8 mutants, respectively. A double mutant had a reduction similar to ΔBbATG1. Additionally, both BbATG1 and BbATG8 affected the levels of conidial protein BbCP15p required for conidiation. The virulence of each autophagy-deficient mutant was considerably weakened as indicated in topical and intrahemocoel injection assays, and showed a greater reduction in topical infection. However, BbATG1 and BbATG8 had different effects on fungal virulence. Our data indicate that these autophagy-related proteins have different functions in fungal stress response, asexual development and virulence. PMID:27197558

  10. The autophagy-related genes BbATG1 and BbATG8 have different functions in differentiation, stress resistance and virulence of mycopathogen Beauveria bassiana.

    PubMed

    Ying, Sheng-Hua; Liu, Jing; Chu, Xin-Ling; Xie, Xue-Qin; Feng, Ming-Guang

    2016-01-01

    Autophagy-related proteins play significantly different roles in eukaryotes. In the entomopathogenic fungus Beauveria bassiana, autophagy is associated with fungal growth and development. BbATG1 (a serine/threonine protein kinase) and BbATG8 (a ubiquitin-like protein) have similar roles in autophagy, but different roles in other processes. Disruption mutants of BbATG1 and BbATG8 had impaired conidial germination under starvation stress. The mutant ΔBbATG8 exhibited enhanced sensitivity to oxidative stress, while a ΔBbATG1 mutant did not. BbATG1 and BbATG8 showed different roles in spore differentiation. The blastospore yield was reduced by 70% and 92% in ΔBbATG1 and ΔBbATG8 mutants, respectively, and the double mutant had a reduction of 95%. Conidial yield was reduced by approximately 90% and 50% in ΔBbATG1 and ΔBbATG8 mutants, respectively. A double mutant had a reduction similar to ΔBbATG1. Additionally, both BbATG1 and BbATG8 affected the levels of conidial protein BbCP15p required for conidiation. The virulence of each autophagy-deficient mutant was considerably weakened as indicated in topical and intrahemocoel injection assays, and showed a greater reduction in topical infection. However, BbATG1 and BbATG8 had different effects on fungal virulence. Our data indicate that these autophagy-related proteins have different functions in fungal stress response, asexual development and virulence. PMID:27197558

  11. Here, there be dragons: charting autophagy-related alterations in human tumors.

    PubMed

    Lebovitz, Chandra B; Bortnik, Svetlana B; Gorski, Sharon M

    2012-03-01

    Macroautophagy (or autophagy) is a catabolic cellular process that is both homeostatic and stress adaptive. Normal cells rely on basal levels of autophagy to maintain cellular integrity (via turnover of long-lived proteins and damaged organelles) and increased levels of autophagy to buoy cell survival during various metabolic stresses (via nutrient and energy provision through lysosomal degradation of cytoplasmic components). Autophagy can function in both tumor suppression and tumor progression, and is under investigation in clinical trials as a novel target for anticancer therapy. However, its role in cancer pathogenesis has yet to be fully explored. In particular, it remains unknown whether in vitro observations will be applicable to human cancer patients. Another outstanding question is whether there exists tumor-specific selection for alterations in autophagy function. In this review, we survey reported mutations in autophagy genes and key autophagy regulators identified in human tumor samples and summarize the literature regarding expression levels of autophagy genes and proteins in various cancer tissues. Although it is too early to draw inferences from this collection of in vivo studies of autophagy-related alterations in human cancers, their results highlight the challenges that must be overcome before we can accurately assess the scope of autophagy's predicted role in tumorigenesis. PMID:22253413

  12. Autophagy Control by the VEGF-C/NRP-2 axis in Cancer and its Implication for Treatment Resistance

    PubMed Central

    Stanton, Marissa J.; Dutta, Samikshan; Zhang, Heyu; Polavaram, Navatha Shree; Leontovich, Alexey A.; Hönscheid, Pia; Sinicrope, Frank A.; Tindall, Donald J.; Muders, Michael H.; Datta, Kaustubh

    2013-01-01

    A major contributor to cancer mortality is recurrence and subsequent metastatic transformation following therapeutic intervention. Therefore, in order to develop new treatment modalities and improve the efficacy of current ones, it is important to understand the molecular mechanisms that promote resistance to therapy in cancer cells. One pathway contributing to therapy resistance is autophagy, a self-digestive process that can eliminate unnecessary or damaged organelles to protect cancer cells from death. We have found that the VEGF-C/NRP-2 axis is involved in the activation of autophagy, which helps cancer cell survival following treatment. Inhibition of mTOR complex 1 activity by this axis is the underlying mechanism for the activation of autophagy. Furthermore, we identified two VEGF-C/NRP-2-regulated genes, LAMP-2 and WDFY-1 that have previously been suggested to participate in autophagy and vesicular trafficking. Up-regulation of WDFY-1 following VEGF-C or NRP-2 depletion contributes to cytotoxic drug-mediated cell death. Together, these data suggest a link between the VEGF-C axis and cancer cell survival despite the presence of chemotherapy-induced stress. Effective targeting of this pathway may lead to the development of new cancer therapies. PMID:23149913

  13. An expanded role for mTORC1 in autophagy

    PubMed Central

    Kim, Young-Mi; Park, Ji-Man; Grunwald, Douglas; Kim, Do-Hyung

    2016-01-01

    Mechanistic target of rapamycin complex 1 (mTORC1) negatively regulates autophagy at early stages by phosphorylating Unc51-like kinase 1 (ULK1). Our recent study expanded the roles of mTORC1 in autophagy by identifying ultraviolet radiation resistance-associated gene product (UVRAG) as a substrate of mTORC1. This finding has provided new insight into the roles of mTORC1 in cellular membrane processes and cancer.

  14. The Parkinson's disease-associated genes ATP13A2 and SYT11 regulate autophagy via a common pathway

    PubMed Central

    Bento, Carla F.; Ashkenazi, Avraham; Jimenez-Sanchez, Maria; Rubinsztein, David C.

    2016-01-01

    Forms of Parkinson's disease (PD) are associated with lysosomal and autophagic dysfunction. ATP13A2, which is mutated in some types of early-onset Parkinsonism, has been suggested as a regulator of the autophagy–lysosome pathway. However, little is known about the ATP13A2 effectors and how they regulate this pathway. Here we show that ATP13A2 depletion negatively regulates another PD-associated gene (SYT11) at both transcriptional and post-translational levels. Decreased SYT11 transcription is controlled by a mechanism dependent on MYCBP2-induced ubiquitination of TSC2, which leads to mTORC1 activation and decreased TFEB-mediated transcription of SYT11, while increased protein turnover is regulated by SYT11 ubiquitination and degradation. Both mechanisms account for a decrease in the levels of SYT11, which, in turn, induces lysosomal dysfunction and impaired degradation of autophagosomes. Thus, we propose that ATP13A2 and SYT11 form a new functional network in the regulation of the autophagy–lysosome pathway, which is likely to contribute to forms of PD-associated neurodegeneration. PMID:27278822

  15. Environmental Correlation Analysis for Genes Associated with Protection against Malaria.

    PubMed

    Mackinnon, Margaret J; Ndila, Carolyne; Uyoga, Sophie; Macharia, Alex; Snow, Robert W; Band, Gavin; Rautanen, Anna; Rockett, Kirk A; Kwiatkowski, Dominic P; Williams, Thomas N

    2016-05-01

    Genome-wide searches for loci involved in human resistance to malaria are currently being conducted on a large scale in Africa using case-control studies. Here, we explore the utility of an alternative approach-"environmental correlation analysis, ECA," which tests for clines in allele frequencies across a gradient of an environmental selection pressure-to identify genes that have historically protected against death from malaria. We collected genotype data from 12,425 newborns on 57 candidate malaria resistance loci and 9,756 single nucleotide polymorphisms (SNPs) selected at random from across the genome, and examined their allele frequencies for geographic correlations with long-term malaria prevalence data based on 84,042 individuals living under different historical selection pressures from malaria in coastal Kenya. None of the 57 candidate SNPs showed significant (P < 0.05) correlations in allele frequency with local malaria transmission intensity after adjusting for population structure and multiple testing. In contrast, two of the random SNPs that had highly significant correlations (P < 0.01) were in genes previously linked to malaria resistance, namely, CDH13, encoding cadherin 13, and HS3ST3B1, encoding heparan sulfate 3-O-sulfotransferase 3B1. Both proteins play a role in glycoprotein-mediated cell-cell adhesion which has been widely implicated in cerebral malaria, the most life-threatening form of this disease. Other top genes, including CTNND2 which encodes δ-catenin, a molecular partner to cadherin, were significantly enriched in cadherin-mediated pathways affecting inflammation of the brain vascular endothelium. These results demonstrate the utility of ECA in the discovery of novel genes and pathways affecting infectious disease. PMID:26744416

  16. Environmental Correlation Analysis for Genes Associated with Protection against Malaria

    PubMed Central

    Mackinnon, Margaret J.; Ndila, Carolyne; Uyoga, Sophie; Macharia, Alex; Snow, Robert W.; Band, Gavin; Rautanen, Anna; Rockett, Kirk A.; Kwiatkowski, Dominic P.; Williams, Thomas N.

    2016-01-01

    Genome-wide searches for loci involved in human resistance to malaria are currently being conducted on a large scale in Africa using case-control studies. Here, we explore the utility of an alternative approach—“environmental correlation analysis, ECA,” which tests for clines in allele frequencies across a gradient of an environmental selection pressure—to identify genes that have historically protected against death from malaria. We collected genotype data from 12,425 newborns on 57 candidate malaria resistance loci and 9,756 single nucleotide polymorphisms (SNPs) selected at random from across the genome, and examined their allele frequencies for geographic correlations with long-term malaria prevalence data based on 84,042 individuals living under different historical selection pressures from malaria in coastal Kenya. None of the 57 candidate SNPs showed significant (P < 0.05) correlations in allele frequency with local malaria transmission intensity after adjusting for population structure and multiple testing. In contrast, two of the random SNPs that had highly significant correlations (P < 0.01) were in genes previously linked to malaria resistance, namely, CDH13, encoding cadherin 13, and HS3ST3B1, encoding heparan sulfate 3-O-sulfotransferase 3B1. Both proteins play a role in glycoprotein-mediated cell-cell adhesion which has been widely implicated in cerebral malaria, the most life-threatening form of this disease. Other top genes, including CTNND2 which encodes δ-catenin, a molecular partner to cadherin, were significantly enriched in cadherin-mediated pathways affecting inflammation of the brain vascular endothelium. These results demonstrate the utility of ECA in the discovery of novel genes and pathways affecting infectious disease. PMID:26744416

  17. Microenvironment and autophagy cross-talk: Implications in cancer therapy.

    PubMed

    Gomes, Luciana R; Vessoni, Alexandre T; Menck, Carlos F M

    2016-05-01

    There are many ongoing clinical trials to validate tumour microenvironment or autophagic pathway components as targets for anticancer therapies. Different components of the tumour microenvironment play important roles in tumour cell responses, directly affecting malignant transformation, drug resistance and metastasis. Autophagy is also related to chemotherapy responses by inducing tumour cell death or survival. Thus, the autophagy pathway may act as oncosuppressor, in addition to protecting cells from chemotherapy. The cross-talk between the microenvironment and autophagy is very complex and poorly understood. In a recent study using a three-dimensional (3D) cell culture model, the well-documented chemotherapy-mediated activation of autophagy was impaired in breast cancer cells, suggesting a context-dependent outcome for autophagy modulators, under the control of the p53 protein. A deeper understanding of this microenvironment/autophagy interplay may provide important clues for identifying differences in the tumour cell signalling network from in vitro basic research studies to the actual clinical context. In this work, we summarize the role of the microenvironment and autophagy in physiological and tumourigenic conditions, their interactions, and the challenges related to the use of drugs that target these pathways in cancer treatment protocols, emphasizing the potential use of 3D cell culture models in preclinical studies. PMID:27037157

  18. Activated Acinus boosts basal autophagy

    PubMed Central

    Nandi, Nilay; Tyra, Lauren K; Krämer, Helmut

    2015-01-01

    Acinus (Acn) is a nuclear protein that participates in the regulation of autophagy. Loss of Acn function prevents autophagy in starving cells. Conversely, Acn activation induces basal autophagy. This enhances the quality control functions of autophagy such as the removal of misfolded proteins, thereby reducing neurodegeneration and prolonging lifespan. Acn activity is enhanced by Akt1-mediated phosphorylation, which counteracts the cleavage of Acn by a caspase-3 homolog. PMID:27308482

  19. Autophagy in diabetic nephropathy.

    PubMed

    Ding, Yan; Choi, Mary E

    2015-01-01

    Diabetic nephropathy (DN) is the most common cause of end-stage kidney disease worldwide, and is associated with increased morbidity and mortality in patients with both type 1 and type 2 diabetes. Increasing prevalence of diabetes has made the need for effective treatment of DN critical and thereby identifying new therapeutic targets to improve clinical management. Autophagy is a highly conserved 'self-eating' pathway by which cells degrade and recycle macromolecules and organelles. Autophagy serves as an essential mechanism to maintain homeostasis of glomeruli and tubules, and plays important roles in human health and diseases. Impairment of autophagy is implicated in the pathogenesis of DN. Emerging body of evidence suggests that targeting the autophagic pathway to activate and restore autophagy activity may be renoprotective. In this review, we examine current advances in our understanding of the roles of autophagy in diabetic kidney injury, focusing on studies in renal cells in culture, human kidney tissues, and experimental animal models of diabetes. We discuss the major nutrient-sensing signal pathways and diabetes-induced altered intracellular metabolism and cellular events, including accumulation of advanced glycation end-products, increased oxidative stress, endoplasmic reticulum stress, hypoxia, and activation of the renin-angiotensin system, which modulate autophagic activity and contribute to the development of DN. We also highlight recent studies of autophagy and transforming growth factor-β in renal fibrosis, the final common response to injury that ultimately leads to end-stage kidney failure in both type 1 and type 2 diabetes. These findings suggest the possibility that autophagy can be a therapeutic target against DN. PMID:25349246

  20. Piperlongumine induces autophagy by targeting p38 signaling.

    PubMed

    Wang, Y; Wang, J-W; Xiao, X; Shan, Y; Xue, B; Jiang, G; He, Q; Chen, J; Xu, H-G; Zhao, R-X; Werle, K D; Cui, R; Liang, J; Li, Y-L; Xu, Z-X

    2013-01-01

    Piperlongumine (PL), a natural product isolated from the plant species Piper longum L., can selectively induce apoptotic cell death in cancer cells by targeting the stress response to reactive oxygen species (ROS). Here we show that PL induces cell death in the presence of benzyloxycarbonylvalyl-alanyl-aspartic acid (O-methyl)-fluoro-methylketone (zVAD-fmk), a pan-apoptotic inhibitor, and in the presence of necrostatin-1, a necrotic inhibitor. Instead PL-induced cell death can be suppressed by 3-methyladenine, an autophagy inhibitor, and substantially attenuated in cells lacking the autophagy-related 5 (Atg5) gene. We further show that PL enhances autophagy activity without blocking autophagy flux. Application of N-acetyl-cysteine, an antioxidant, markedly reduces PL-induced autophagy and cell death, suggesting an essential role for intracellular ROS in PL-induced autophagy. Furthermore, PL stimulates the activation of p38 protein kinase through ROS-induced stress response and p38 signaling is necessary for the action of PL as SB203580, a p38 inhibitor, or dominant-negative p38 can effectively reduce PL-mediated autophagy. Thus, we have characterized a new mechanism for PL-induced cell death through the ROS-p38 pathway. Our findings support the therapeutic potential of PL by triggering autophagic cell death. PMID:24091667

  1. Autophagy and Transporter-Based Multi-Drug Resistance

    PubMed Central

    Kumar, Priyank; Zhang, Dong-Mei; Degenhardt, Kurt; Chen, Zhe-Sheng

    2012-01-01

    All the therapeutic strategies for treating cancers aim at killing the cancer cells via apoptosis (programmed cell death type I). Defective apoptosis endow tumor cells with survival. The cell can respond to such defects with autophagy. Autophagy is a cellular process by which cytoplasmic material is either degraded to maintain homeostasis or recycled for energy and nutrients in starvation. A plethora of evidence has shown that the role of autophagy in tumors is complex. A lot of effort is needed to underline the functional status of autophagy in tumor progression and treatment, and elucidate how to tweak autophagy to treat cancer. Furthermore, during the treatment of cancer, the limitation for the cure rate and survival is the phenomenon of multi drug resistance (MDR). The development of MDR is an intricate process that could be regulated by drug transporters, enzymes, anti-apoptotic genes or DNA repair mechanisms. Reports have shown that autophagy has a dual role in MDR. Furthermore, it has been reported that activation of a death pathway may overcome MDR, thus pointing the importance of other death pathways to regulate tumor cell progression and growth. Therefore, in this review we will discuss the role of autophagy in MDR tumors and a possible link amongst these phenomena. PMID:24710490

  2. Transcriptional regulation of mammalian autophagy at a glance.

    PubMed

    Füllgrabe, Jens; Ghislat, Ghita; Cho, Dong-Hyung; Rubinsztein, David C

    2016-08-15

    Macroautophagy, hereafter referred to as autophagy, is a catabolic process that results in the lysosomal degradation of cytoplasmic contents ranging from abnormal proteins to damaged cell organelles. It is activated  under diverse conditions, including nutrient deprivation and hypoxia. During autophagy, members of the core autophagy-related (ATG) family of proteins mediate membrane rearrangements, which lead to the engulfment and degradation of cytoplasmic cargo. Recently, the nuclear regulation of autophagy, especially by transcription factors and histone modifiers, has gained increased attention. These factors are not only involved in rapid responses to autophagic stimuli, but also regulate the long-term outcome of autophagy. Now there are more than 20 transcription factors that have been shown to be linked to the autophagic process. However, their interplay and timing appear enigmatic as several have been individually shown to act as major regulators of autophagy. This Cell Science at a Glance article and the accompanying poster highlights the main cellular regulators of transcription involved in mammalian autophagy and their target genes. PMID:27528206

  3. Autophagy in osteoblasts is involved in mineralization and bone homeostasis

    PubMed Central

    Nollet, Marie; Santucci-Darmanin, Sabine; Breuil, Véronique; Al-Sahlanee, Rasha; Cros, Chantal; Topi, Majlinda; Momier, David; Samson, Michel; Pagnotta, Sophie; Cailleteau, Laurence; Battaglia, Séverine; Farlay, Delphine; Dacquin, Romain; Barois, Nicolas; Jurdic, Pierre; Boivin, Georges; Heymann, Dominique; Lafont, Frank; Lu, Shi Shou; Dempster, David W; Carle, Georges F; Pierrefite-Carle, Valérie

    2014-01-01

    Bone remodeling is a tightly controlled mechanism in which osteoblasts (OB), the cells responsible for bone formation, osteoclasts (OC), the cells specialized for bone resorption, and osteocytes, the multifunctional mechanosensing cells embedded in the bone matrix, are the main actors. Increased oxidative stress in OB, the cells producing and mineralizing bone matrix, has been associated with osteoporosis development but the role of autophagy in OB has not yet been addressed. This is the goal of the present study. We first show that the autophagic process is induced in OB during mineralization. Then, using knockdown of autophagy-essential genes and OB-specific autophagy-deficient mice, we demonstrate that autophagy deficiency reduces mineralization capacity. Moreover, our data suggest that autophagic vacuoles could be used as vehicles in OB to secrete apatite crystals. In addition, autophagy-deficient OB exhibit increased oxidative stress and secretion of the receptor activator of NFKB1 (TNFSF11/RANKL), favoring generation of OC, the cells specialized in bone resorption. In vivo, we observed a 50% reduction in trabecular bone mass in OB-specific autophagy-deficient mice. Taken together, our results show for the first time that autophagy in OB is involved both in the mineralization process and in bone homeostasis. These findings are of importance for mineralized tissues which extend from corals to vertebrates and uncover new therapeutic targets for calcified tissue-related metabolic pathologies. PMID:25484092

  4. Autophagy mediates phase transitions from cell death to life.

    PubMed

    Han, Kyungreem; Kim, Jinwoong; Choi, MooYoung

    2015-09-01

    Autophagy is a lysosomal degradation pathway, which is critical for maintaining normal cellular functions. Despite considerable advances in defining the specific molecular mechanism governing the autophagy pathway during the last decades, we are still far from understanding the underlying principle of the autophagy machinery and its complex role in human disease. As an alternative attempt to reinvigorate the search for the principle of the autophagy pathway, we in this study make use of the computer-aided analysis, complementing current molecular-level studies of autophagy. Specifically, we propose a hypothesis that autophagy mediates cellular phase transitions and demonstrate that the autophagic phase transitions are essential to the maintenance of normal cellular functions and critical in the fate of a cell, i.e., cell death or survival. This study should provide valuable insight into how interactions of sub-cellular components such as genes and protein modules/complexes regulate autophagy and then impact on the dynamic behaviors of living cells as a whole, bridging the microscopic molecular-level studies and the macroscopic cellular-level and physiological approaches. PMID:27441218

  5. Baicalein pretreatment reduces liver ischemia/reperfusion injury via induction of autophagy in rats

    PubMed Central

    Liu, Anding; Huang, Liang; Guo, Enshuang; Li, Renlong; Yang, Jiankun; Li, Anyi; Yang, Yan; Liu, Shenpei; Hu, Jifa; Jiang, Xiaojing; Dirsch, Olaf; Dahmen, Uta; Sun, Jian

    2016-01-01

    We previously demonstrated that baicalein could protect against liver ischemia/reperfusion (I/R) injury in mice. The exact mechanism of baicalein remains poorly understood. Autophagy plays an important role in protecting against I/R injury. This study was designed to determine whether baicalein could protect against liver I/R injury via induction of autophagy in rats. Baicalein was intraperitoneally injected 1 h before warm ischemia. Pretreatment with baicalein prior to I/R insult significantly blunted I/R-induced elevations of serum aminotransferase levels and significantly improved the histological status of livers. Electron microscopy and expression of the autophagic marker LC3B-II suggested induction of autophagy after baicalein treatment. Moreover, inhibition of the baicalein-induced autophagy using 3-methyladenine (3-MA) worsened liver injury. Furthermore, baicalein treatment increased heme oxygenase (HO)-1 expression, and pharmacological inhibition of HO-1 with tin protoporphyrin IX (SnPP) abolished the baicalein-mediated autophagy and the hepatocellular protection. In primary rat hepatocytes, baicalein-induced autophagy also protected hepatocytes from hypoxia/reoxygenation injury in vitro and the beneficial effect was abrogated by 3-MA or Atg7 siRNA, respectively. Suppression of HO-1 activity by SnPP or HO-1 siRNA prevented the baicalein-mediated autophagy and resulted in increased hepatocellular injury. Collectively, these results suggest that baicalein prevents hepatocellular injury via induction of HO-1-mediated autophagy. PMID:27150843

  6. Oxidative stress contributes to autophagy induction in response to endoplasmic reticulum stress in Chlamydomonas reinhardtii.

    PubMed

    Pérez-Martín, Marta; Pérez-Pérez, María Esther; Lemaire, Stéphane D; Crespo, José L

    2014-10-01

    The accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER) results in the activation of stress responses, such as the unfolded protein response or the catabolic process of autophagy to ultimately recover cellular homeostasis. ER stress also promotes the production of reactive oxygen species, which play an important role in autophagy regulation. However, it remains unknown whether reactive oxygen species are involved in ER stress-induced autophagy. In this study, we provide evidence connecting redox imbalance caused by ER stress and autophagy activation in the model unicellular green alga Chlamydomonas reinhardtii. Treatment of C. reinhardtii cells with the ER stressors tunicamycin or dithiothreitol resulted in up-regulation of the expression of genes encoding ER resident endoplasmic reticulum oxidoreductin1 oxidoreductase and protein disulfide isomerases. ER stress also triggered autophagy in C. reinhardtii based on the protein abundance, lipidation, cellular distribution, and mRNA levels of the autophagy marker ATG8. Moreover, increases in the oxidation of the glutathione pool and the expression of oxidative stress-related genes were detected in tunicamycin-treated cells. Our results revealed that the antioxidant glutathione partially suppressed ER stress-induced autophagy and decreased the toxicity of tunicamycin, suggesting that oxidative stress participates in the control of autophagy in response to ER stress in C. reinhardtii In close agreement, we also found that autophagy activation by tunicamycin was more pronounced in the C. reinhardtii sor1 mutant, which shows increased expression of oxidative stress-related genes. PMID:25143584

  7. Nitric oxide induces apoptosis and autophagy; autophagy down-regulates NO synthesis in physalin A-treated A375-S2 human melanoma cells.

    PubMed

    He, Hao; Feng, Yong-Sheng; Zang, Ling-He; Liu, Wei-Wei; Ding, Li-Qin; Chen, Li-Xia; Kang, Ning; Hayashi, Toshihiko; Tashiro, Shin-ichi; Onodera, Satoshi; Qiu, Feng; Ikejima, Takashi

    2014-09-01

    Physalin A is an active withanolide isolated from Physalis alkekengi var. franchetii, a traditional Chinese herbal medicine named Jindenglong, which has been used for the treatment of sore throat, hepatitis, eczema and tumors in China. Our previous study demonstrated that physalin A induced apoptosis and cyto-protective autophagy in A375-S2 human melanoma cells. Induction of reactive oxygen species (ROS) with physalin A triggered apoptosis. In this study, NO generated by physalin A induced apoptosis and autophagy in A375-S2 cells, since physalin A induced the expression of inducible nitric oxide synthase (iNOS) in the cells. Generation of NO partially promoted both apoptosis and autophagy in A375-S2 cells. NO suppressed mTOR expression, which led to autophagy induction. An autophagic inhibitor, 3-methyladenine (3MA) promoted NO production, while acceleration of autophagy with an autophagic agonist rapamycin repressed NO production, suggesting that autophagy and NO production form a negative feedback loop that eventually protects the cells from apoptosis. The results together with the previous study indicate apoptosis and autophagy induced by physalin A in A375-S2 cells; the autophagy, repressing production of reactive nitrogen species (RNS) and ROS, protects the cells from apoptosis. PMID:24952311

  8. The Interplays between Autophagy and Apoptosis Induced by Enterovirus 71

    PubMed Central

    Wang, Bei; Wang, Tao; Wang, Ji; Huang, He; Wang, Jianwei; Jin, Qi; Zhao, Zhendong

    2013-01-01

    Background Enterovirus 71 (EV71) is the causative agent of human diseases with distinct severity, from mild hand, foot and mouth disease to severe neurological syndromes, such as encephalitis and meningitis. The lack of understanding of viral pathogenesis as well as lack of efficient vaccine and drugs against this virus impedes the control of EV71 infection. EV71 virus induces autophagy and apoptosis; however, the relationship between EV71-induced autophagy and apoptosis as well as the influence of autophagy and apoptosis on virus virulence remains unclear. Methodology/Principal Findings In this study, it was observed that the Anhui strain of EV71 induced autophagy and apoptosis in human rhabdomyosarcoma (RD-A) cells. Additionally, by either applying chemical inhibitors or knocking down single essential autophagic or apoptotic genes, inhibition of EV71 induced autophagy inhibited the apoptosis both at the autophagosome formation stage and autophagy execution stage. However, inhibition of autophagy at the stage of autophagosome and lysosome fusion promoted apoptosis. In reverse, the inhibition of EV71-induced apoptosis contributed to the conversion of microtubule-associated protein 1 light chain 3-I (LC3-I) to LC3-II and degradation of sequestosome 1 (SQSTM1/P62). Furthermore, the inhibition of autophagy in the autophagsome formation stage or apoptosis decreased the release of EV71 viral particles. Conclusions/Significance In conclusion, the results of this study not only revealed novel aspect of the interplay between autophagy and apoptosis in EV71 infection, but also provided a new insight to control EV71 infection. PMID:23437282

  9. Angiogenic growth factor axis in autophagy regulation.

    PubMed

    Stanton, Marissa J; Dutta, Samikshan; Polavaram, Navatha Shree; Roy, Sohini; Muders, Michael H; Datta, Kaustubh

    2013-05-01

    Understanding the molecular mechanisms promoting therapy resistance is important. Previously, we reported that VEGFC can promote cancer cell survival during stress via interaction with its receptor NRP2. While examining the molecular mechanisms involved in this survival, we performed a microarray study in which we identified two genes, WDFY1 and LAMP2, which have been suggested to function in autophagy. Our subsequent studies further confirmed the regulation of autophagy by the VEGFC-NRP2 axis in cancer during starvation- and chemotherapy-induced stress. We are currently in the process of determining the mechanism(s) through which WDFY1 and LAMP2 control autophagy; however, we did observe an increase in MTOR complex 1 (MTORC1) activity after the depletion of the VEGFC-NRP2 axis. It would therefore be interesting to study whether WDFY1 and LAMP2 can influence MTORC1 activity and regulate autophagy. Taken together, our data suggest that targeting the VEGFC-NRP2 axis in combination with chemotherapy could be an effective treatment for advanced cancers. PMID:23388383

  10. Trehalose Accumulation Triggers Autophagy during Plant Desiccation.

    PubMed

    Williams, Brett; Njaci, Isaac; Moghaddam, Lalehvash; Long, Hao; Dickman, Martin B; Zhang, Xiuren; Mundree, Sagadevan

    2015-12-01

    Global climate change, increasingly erratic weather and a burgeoning global population are significant threats to the sustainability of future crop production. There is an urgent need for the development of robust measures that enable crops to withstand the uncertainty of climate change whilst still producing maximum yields. Resurrection plants possess the unique ability to withstand desiccation for prolonged periods, can be restored upon watering and represent great potential for the development of stress tolerant crops. Here, we describe the remarkable stress characteristics of Tripogon loliiformis, an uncharacterised resurrection grass and close relative of the economically important cereals, rice, sorghum, and maize. We show that T. loliiformis survives extreme environmental stress by implementing autophagy to prevent Programmed Cell Death. Notably, we identified a novel role for trehalose in the regulation of autophagy in T.loliiformis. Transcriptome, Gas Chromatography Mass Spectrometry, immunoblotting and confocal microscopy analyses directly linked the accumulation of trehalose with the onset of autophagy in dehydrating and desiccated T. loliiformis shoots. These results were supported in vitro with the observation of autophagosomes in trehalose treated T. loliiformis leaves; autophagosomes were not detected in untreated samples. Presumably, once induced, autophagy promotes desiccation tolerance in T.loliiformis, by removal of cellular toxins to suppress programmed cell death and the recycling of nutrients to delay the onset of senescence. These findings illustrate how resurrection plants manipulate sugar metabolism to promote desiccation tolerance and may provide candidate genes that are potentially useful for the development of stress tolerant crops. PMID:26633550

  11. Trehalose Accumulation Triggers Autophagy during Plant Desiccation

    PubMed Central

    Moghaddam, Lalehvash; Long, Hao; Dickman, Martin B; Zhang, Xiuren; Mundree, Sagadevan

    2015-01-01

    Global climate change, increasingly erratic weather and a burgeoning global population are significant threats to the sustainability of future crop production. There is an urgent need for the development of robust measures that enable crops to withstand the uncertainty of climate change whilst still producing maximum yields. Resurrection plants possess the unique ability to withstand desiccation for prolonged periods, can be restored upon watering and represent great potential for the development of stress tolerant crops. Here, we describe the remarkable stress characteristics of Tripogon loliiformis, an uncharacterised resurrection grass and close relative of the economically important cereals, rice, sorghum, and maize. We show that T. loliiformis survives extreme environmental stress by implementing autophagy to prevent Programmed Cell Death. Notably, we identified a novel role for trehalose in the regulation of autophagy in T.loliiformis. Transcriptome, Gas Chromatography Mass Spectrometry, immunoblotting and confocal microscopy analyses directly linked the accumulation of trehalose with the onset of autophagy in dehydrating and desiccated T. loliiformis shoots. These results were supported in vitro with the observation of autophagosomes in trehalose treated T. loliiformis leaves; autophagosomes were not detected in untreated samples. Presumably, once induced, autophagy promotes desiccation tolerance in T.loliiformis, by removal of cellular toxins to suppress programmed cell death and the recycling of nutrients to delay the onset of senescence. These findings illustrate how resurrection plants manipulate sugar metabolism to promote desiccation tolerance and may provide candidate genes that are potentially useful for the development of stress tolerant crops. PMID:26633550

  12. Avermectin induced autophagy in pigeon spleen tissues.

    PubMed

    Liu, Ci; Zhao, Yanbing; Chen, Lijie; Zhang, Ziwei; Li, Ming; Li, Shu

    2015-12-01

    The level of autophagy is considered as an indicator for monitoring the toxic impact of pesticide exposure. Avermectin (AVM), a widely used insecticide, has immunotoxic effects on the pigeon spleen. The aim of this study was to investigate the status of autophagy and the expression levels of microtubule-associated protein1 light chain 3 (LC3), beclin-1, dynein, autophagy associated gene (Atg) 4B, Atg5, target of rapamycin complex 1 (TORC1) and target of rapamycin complex 2 (TORC2) in AVM-treated pigeon spleens. Eighty two-month-old pigeons were randomly divided into four groups: a control group, a low-dose group, a medium-dose group and a high-dose group, which were fed a basal diet spiked with 0, 20, 40 and 60 mg AVM/kg diet, respectively. Microscopic cellular morphology revealed a significant increase in autophagic structures in the AVM-treated groups. The expression of LC3, beclin-1, dynein, Atg4B and Atg5 increased, while mRNA levels of TORC1 and TORC2 were decreased in the AVM-treated groups relative to the control groups at 30, 60 and 90 days in the pigeon spleen. These results indicated that AVM exposure could up-regulate the level of autophagy in a dose-time-dependent manner in the pigeon spleen. PMID:26541719

  13. Autophagy in plant pathogenic fungi.

    PubMed

    Liu, Xiao-Hong; Xu, Fei; Snyder, John Hugh; Shi, Huan-Bin; Lu, Jian-Ping; Lin, Fu-Cheng

    2016-09-01

    Autophagy is a conserved cellular process that degrades cytoplasmic constituents in vacuoles. Plant pathogenic fungi develop special infection structures and/or secrete a range of enzymes to invade their plant hosts. It has been demonstrated that monitoring autophagy processes can be extremely useful in visualizing the sequence of events leading to pathogenicity of plant pathogenic fungi. In this review, we introduce the molecular mechanisms involved in autophagy. In addition, we explore the relationship between autophagy and pathogenicity in plant pathogenic fungi. Finally, we discuss the various experimental strategies available for use in the study of autophagy in plant pathogenic fungi. PMID:27072489

  14. Autophagy and Immune Senescence.

    PubMed

    Zhang, Hanlin; Puleston, Daniel J; Simon, Anna Katharina

    2016-08-01

    With extension of the average lifespan, aging has become a heavy burden in society. Immune senescence is a key risk factor for many age-related diseases such as cancer and increased infections in the elderly, and hence has elicited much attention in recent years. As our body's guardian, the immune system maintains systemic health through removal of pathogens and damage. Autophagy is an important cellular 'clearance' process by which a cell internally delivers damaged organelles and macromolecules to lysosomes for degradation. Here, we discuss the most current knowledge of how impaired autophagy can lead to cellular and immune senescence. We also provide an overview, with examples, of the clinical potential of exploiting autophagy to delay immune senescence and/or rejuvenate immunity to treat various age-related diseases. PMID:27395769

  15. The autophagy protein Atg7 is essential for hematopoietic stem cell maintenance

    PubMed Central

    Mortensen, Monika; Soilleux, Elizabeth J.; Djordjevic, Gordana; Tripp, Rebecca; Lutteropp, Michael; Sadighi-Akha, Elham; Stranks, Amanda J.; Glanville, Julie; Knight, Samantha; W. Jacobsen, Sten-Eirik; Kranc, Kamil R.

    2011-01-01

    The role of autophagy, a lysosomal degradation pathway which prevents cellular damage, in the maintenance of adult mouse hematopoietic stem cells (HSCs) remains unknown. Although normal HSCs sustain life-long hematopoiesis, malignant transformation of HSCs leads to leukemia. Therefore, mechanisms protecting HSCs from cellular damage are essential to prevent hematopoietic malignancies. In this study, we crippled autophagy in HSCs by conditionally deleting the essential autophagy gene Atg7 in the hematopoietic system. This resulted in the loss of normal HSC functions, a severe myeloproliferation, and death of the mice within weeks. The hematopoietic stem and progenitor cell compartment displayed an accumulation of mitochondria and reactive oxygen species, as well as increased proliferation and DNA damage. HSCs within the Lin−Sca-1+c-Kit+ (LSK) compartment were significantly reduced. Although the overall LSK compartment was expanded, Atg7-deficient LSK cells failed to reconstitute the hematopoietic system of lethally irradiated mice. Consistent with loss of HSC functions, the production of both lymphoid and myeloid progenitors was impaired in the absence of Atg7. Collectively, these data show that Atg7 is an essential regulator of adult HSC maintenance. PMID:21339326

  16. Autophagy in non-small cell lung carcinogenesis

    PubMed Central

    Rao, Shuan; Yang, Heng; Penninger, Josef M; Kroemer, Guido

    2014-01-01

    In a mouse model of non-small cell lung carcinogenesis, we recently found that the inactivation of the essential autophagy gene Atg5 causes an acceleration of the early phases of oncogenesis. Thus, hyperplastic lesions and adenomas are more frequent at early stages after adenoviral delivery of Cre recombinase via inhalation, when Cre—in addition to activating the KRasG12D oncogene—inactivates both alleles of the Atg5 gene. The accelerated oncogenesis of autophagy-deficient tumors developing in KRas;Atg5fl/fl mice (as compared with autophagy-competent KRas;Atg5fl/+ control tumors) correlates with an increased infiltration by FOXP3+ regulatory T cells (Tregs). Depletion of such Tregs by means of specific monoclonal antibodies inhibits the accelerated oncogenesis of autophagy-deficient tumors down to the level observed in autophagy-competent controls. Subsequent analyses revealed that the combination of KRas activation and Atg5 inactivation favors the expression of ENTPD1/CD39, an ecto-ATPase that initiates the conversion of extracellular ATP, which is immunostimulatory, into adenosine, which is immunosuppressive. Pharmacological inhibition of ENTPD1 or blockade of adenosinergic receptors reduces the infiltration of KRas;Atg5fl/fl tumors by Tregs and reverses accelerated oncogenesis. Altogether these data favor a model according to which autophagy deficiency favors oncogenesis via changes in the tumor microenvironment that ultimately entail the Treg-mediated inhibition of anticancer immunosurveillance. PMID:24413089

  17. Retinoid receptor signaling and autophagy in acute promyelocytic leukemia

    SciTech Connect

    Orfali, Nina; McKenna, Sharon L.; Cahill, Mary R.; Gudas, Lorraine J.; Mongan, Nigel P.

    2014-05-15

    Retinoids are a family of signaling molecules derived from vitamin A with well established roles in cellular differentiation. Physiologically active retinoids mediate transcriptional effects on cells through interactions with retinoic acid (RARs) and retinoid-X (RXR) receptors. Chromosomal translocations involving the RARα gene, which lead to impaired retinoid signaling, are implicated in acute promyelocytic leukemia (APL). All-trans-retinoic acid (ATRA), alone and in combination with arsenic trioxide (ATO), restores differentiation in APL cells and promotes degradation of the abnormal oncogenic fusion protein through several proteolytic mechanisms. RARα fusion-protein elimination is emerging as critical to obtaining sustained remission and long-term cure in APL. Autophagy is a degradative cellular pathway involved in protein turnover. Both ATRA and ATO also induce autophagy in APL cells. Enhancing autophagy may therefore be of therapeutic benefit in resistant APL and could broaden the application of differentiation therapy to other cancers. Here we discuss retinoid signaling in hematopoiesis, leukemogenesis, and APL treatment. We highlight autophagy as a potential important regulator in anti-leukemic strategies. - Highlights: • Normal and aberrant retinoid signaling in hematopoiesis and leukemia is reviewed. • We suggest a novel role for RARα in the development of X-RARα gene fusions in APL. • ATRA therapy in APL activates transcription and promotes onco-protein degradation. • Autophagy may be involved in both onco-protein degradation and differentiation. • Pharmacologic autophagy induction may potentiate ATRA's therapeutic effects.

  18. Autophagy in alcoholic liver disease, self-eating triggered by drinking.

    PubMed

    Wang, Lin; Khambu, Bilon; Zhang, Hao; Yin, Xiao-Ming

    2015-09-01

    Macroautophagy (autophagy) is an evolutionarily conserved mechanism. It is important for normal cellular function and also plays critical roles in the etiology and pathogenesis of a number of human diseases. In alcohol-induced liver disease, autophagy is a protective mechanism against the liver injury caused by alcohol. Autophagy is activated in acute ethanol treatment but could be suppressed in chronic and/or high dose treatment of alcohol. The selective removal of lipid droplets and/or damaged mitochondria is likely the major mode of autophagy in reducing liver injury. Understanding the dynamics of the autophagy process and the approach to modulate autophagy could help finding new ways to battle against alcohol-induced liver injury. PMID:26186877

  19. Targeting autophagy as a potential therapeutic approach for immune thrombocytopenia therapy.

    PubMed

    Shan, Ning-Ning; Dong, Li-Li; Zhang, Xiao-Mei; Liu, Xin; Li, Ying

    2016-04-01

    Autophagy involves the sequestration and lysosomal degradation of various cytoplasmic structures, including damaged organelles and invading microorganisms. Autophagy is not only an essential cell-intrinsic mechanism for protecting against internal and external stress conditions but is also key in the cellular response against microbes, in antigen processing for major histocompatibility complex (MHC) presentation, and in lymphocyte development, survival, and proliferation. In recent years, perturbations in autophagy have been implicated in a number of diseases, including autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). Immune thrombocytopenia (ITP) is a multifactorial disease characterized by autoimmune responses to self-platelet membrane proteins. Recently, our unpublished original data demonstrated aberrant expression of molecules in the autophagy pathway in ITP patients compared with controls, and we found a close correlation between the pathogenesis of ITP and the autophagy pathway. The potential of targeting the autophagy pathway in ITP as a novel therapeutic approach has been discussed. PMID:26830007

  20. SIRT6 suppresses isoproterenol-induced cardiac hypertrophy through activation of autophagy.

    PubMed

    Lu, Jing; Sun, Duanping; Liu, Zhiping; Li, Min; Hong, Huiqi; Liu, Cui; Gao, Si; Li, Hong; Cai, Yi; Chen, Shaorui; Li, Zhuoming; Ye, Jiantao; Liu, Peiqing

    2016-06-01

    Reduction in autophagy has been reported to contribute to the pathogenesis of cardiac hypertrophy. However, the molecular pathways leading to impaired autophagy at the presence of hypertrophic stimuli remain to be elucidated. The present study aimed to investigate the role of sirtuin 6 (SIRT6), a sirtuin family member, in regulating cardiomyocyte autophagy, and its implication in prevention of cardiac hypertrophy. Primary neonatal rat cardiomyocytes (NRCMs) or Sprague-Dawley (SD) rats were submitted to isoproterenol (ISO) treatment, and then the hypertrophic responses and changes in autophagy activity were measured. The influence of SIRT6 on autophagy was observed in cultured NRCMs with gain- and loss-of-function approaches to regulate SIRT6 expression, and further confirmed in vivo by intramyocardial delivery of an adenovirus vector encoding SIRT6 cDNA. In addition, the involvement of SIRT6-mediated autophagy in attenuation of cardiomyocyte hypertrophy induced by ISO was determined basing on genetic or pharmaceutical disruption of autophagy, and the underlying mechanism was preliminarily explored. ISO-caused cardiac hypertrophy accompanying with a significant decrease in autophagy activity. SIRT6 overexpression enhanced autophagy in NRCMs and in rat hearts, whereas knockdown of SIRT6 by RNA interference led to suppression of cardiomyocyte autophagy. Furthermore, the protective effect of SIRT6 against ISO-stimulated hypertrophy was associated with induction of autophagy. SIRT6 promoted nuclear retention of forkhead box O3 transcription factor possibly via attenuating Akt signaling, which was responsible for autophagy activation. Our findings revealed that SIRT6 positively regulates autophagy in cardiomyocytes, which may help to ameliorate ISO-induced cardiac hypertrophy. PMID:27016702

  1. Hypoxia-induced autophagy mediates cisplatin resistance in lung cancer cells

    PubMed Central

    Wu, Hui-Mei; Jiang, Zi-Feng; Ding, Pei-Shan; Shao, Li-Jie; Liu, Rong-Yu

    2015-01-01

    Hypoxia which commonly exists in solid tumors, leads to cancer cells chemoresistance via provoking adaptive responses including autophagy. Therefore, we sought to evaluate the role of autophagy and hypoxia as well as the underlying mechanism in the cisplatin resistance of lung cancer cells. Our study demonstrated that hypoxia significantly protected A549 and SPC-A1 cells from cisplatin-induced cell death in a Hif-1α- and Hif-2α- dependent manner. Moreover, compared with normoxia, cisplatin-induced apoptosis under hypoxia was markedly reduced. However, when autophagy was inhibited by 3-MA or siRNA targeted ATG5, this reduction was effectively attenuated, which means autophagy mediates cisplatin resisitance under hypoxia. In parallel, we showed that hypoxia robustly augmented cisplatin-induced autophagy activation, accompanying by suppressing cisplatin-induced BNIP3 death pathways, which was due to the more efficient autophagic process under hypoxia. Consequently, we proposed that autophagy was a protective mechanism after cisplatin incubation under both normoxia and hypoxia. However, under normoxia, autophagy activation ‘was unable to counteract the stress induced by cisplatin, therefore resulting in cell death, whereas under hypoxia, autophagy induction was augmented that solved the cisplatin-induced stress, allowing the cells to survival. In conclusion, augmented induction of autophagy by hypoxia decreased lung cancer cells susceptibility to cisplatin-induced apoptosis. PMID:26201611

  2. Defective autophagy is a key feature of cerebral cavernous malformations

    PubMed Central

    Marchi, Saverio; Corricelli, Mariangela; Trapani, Eliana; Bravi, Luca; Pittaro, Alessandra; Delle Monache, Simona; Ferroni, Letizia; Patergnani, Simone; Missiroli, Sonia; Goitre, Luca; Trabalzini, Lorenza; Rimessi, Alessandro; Giorgi, Carlotta; Zavan, Barbara; Cassoni, Paola; Dejana, Elisabetta; Retta, Saverio Francesco; Pinton, Paolo

    2015-01-01

    Cerebral cavernous malformation (CCM) is a major cerebrovascular disease affecting approximately 0.3–0.5% of the population and is characterized by enlarged and leaky capillaries that predispose to seizures, focal neurological deficits, and fatal intracerebral hemorrhages. Cerebral cavernous malformation is a genetic disease that may arise sporadically or be inherited as an autosomal dominant condition with incomplete penetrance and variable expressivity. Causative loss-of-function mutations have been identified in three genes, KRIT1 (CCM1), CCM2 (MGC4607), and PDCD10 (CCM3), which occur in both sporadic and familial forms. Autophagy is a bulk degradation process that maintains intracellular homeostasis and that plays essential quality control functions within the cell. Indeed, several studies have identified the association between dysregulated autophagy and different human diseases. Here, we show that the ablation of the KRIT1 gene strongly suppresses autophagy, leading to the aberrant accumulation of the autophagy adaptor p62/SQSTM1, defective quality control systems, and increased intracellular stress. KRIT1 loss-of-function activates the mTOR-ULK1 pathway, which is a master regulator of autophagy, and treatment with mTOR inhibitors rescues some of the mole-cular and cellular phenotypes associated with CCM. Insufficient autophagy is also evident in CCM2-silenced human endothelial cells and in both cells and tissues from an endothelial-specific CCM3-knockout mouse model, as well as in human CCM lesions. Furthermore, defective autophagy is highly correlated to endothelial-to-mesenchymal transition, a crucial event that contributes to CCM progression. Taken together, our data point to a key role for defective autophagy in CCM disease pathogenesis, thus providing a novel framework for the development of new pharmacological strategies to prevent or reverse adverse clinical outcomes of CCM lesions. PMID:26417067

  3. Implications of the Interaction Between miRNAs and Autophagy in Osteoporosis.

    PubMed

    Shen, Gengyang; Ren, Hui; Qiu, Ting; Liang, De; Xie, Bo; Zhang, Zhida; Yao, Zhensong; Yang, Zhidong; Jiang, Xiaobing

    2016-07-01

    Imbalances between bone formation and resorption are the primary cause of osteoporosis. However, currently, a detailed molecular mechanism of osteoporosis is not available. Autophagy is the conserved process characterized by degrading and recycling aggregated proteins, intracellular pathogens, and damaged organelles. MicroRNAs (miRNAs) are novel regulatory factors that play important roles in numerous cellular processes, including autophagy, through the posttranscriptional regulation of gene expression. Conversely, autophagy plays a role in the regulation of miRNA homeostasis. Recent advances have revealed that both autophagy and miRNAs are involved in the maintenance of bone homoeostasis, whereas the role of the interaction of miRNAs with autophagy in osteoporosis remains unclear. In this paper, we review previous reports on autophagy, miRNAs, and their interaction in osteoporosis. PMID:26922423

  4. Autophagy sustains the replication of porcine reproductive and respiratory virus in host cells

    SciTech Connect

    Liu, Qinghao; Qin, Yixian; Zhou, Lei; Kou, Qiuwen; Guo, Xin; Ge, Xinna; Yang, Hanchun; Hu, Hongbo

    2012-08-01

    In this study, we confirmed the autophagy induced by porcine reproductive and respiratory syndrome virus (PRRSV) in permissive cells and investigated the role of autophagy in the replication of PRRSV. We first demonstrated that PRRSV infection significantly results in the increased double-membrane vesicles, the accumulation of LC3 fluorescence puncta, and the raised ratio of LC3-II/{beta}-actin, in MARC-145 cells. Then we discovered that induction of autophagy by rapamycin significantly enhances the viral titers of PRRSV, while inhibition of autophagy by 3-MA and silencing of LC3 gene by siRNA reduces the yield of PRRSV. The results showed functional autolysosomes can be formed after PRRSV infection and the autophagosome-lysosome-fusion inhibitor decreases the virus titers. We also examined the induction of autophagy by PRRSV infection in pulmonary alveolar macrophages. These findings indicate that autophagy induced by PRRSV infection plays a role in sustaining the replication of PRRSV in host cells.

  5. Autophagy downregulation contributes to insulin resistance mediated injury in insulin receptor knockout podocytes in vitro

    PubMed Central

    Xin, Wei; Li, Zhaoping; Chen, Liyong

    2016-01-01

    It is unknown whether autophagy activity is altered in insulin resistant podocytes and whether autophagy could be a therapeutic target for diabetic nephropathy (DN). Here we used shRNA transfection to knockdown the insulin receptor (IR) gene in cultured human immortalized podocytes as an in vitro insulin resistant model. Autophagy related proteins LC3, Beclin, and p62 as well as nephrin, a podocyte injury marker, were assessed using western blot and immunofluorescence staining. Our results show that autophagy is suppressed when podocytes lose insulin sensitivity and that treatment of rapamycin, an mTOR specific inhibitor, could attenuate insulin resistance induced podocytes injury via autophagy activation. The present study deepens our understanding of the role of autophagy in the pathogenesis of DN. PMID:27077005

  6. Mutation in ATG5 reduces autophagy and leads to ataxia with developmental delay.

    PubMed

    Kim, Myungjin; Sandford, Erin; Gatica, Damian; Qiu, Yu; Liu, Xu; Zheng, Yumei; Schulman, Brenda A; Xu, Jishu; Semple, Ian; Ro, Seung-Hyun; Kim, Boyoung; Mavioglu, R Nehir; Tolun, Aslıhan; Jipa, Andras; Takats, Szabolcs; Karpati, Manuela; Li, Jun Z; Yapici, Zuhal; Juhasz, Gabor; Lee, Jun Hee; Klionsky, Daniel J; Burmeister, Margit

    2016-01-01

    Autophagy is required for the homeostasis of cellular material and is proposed to be involved in many aspects of health. Defects in the autophagy pathway have been observed in neurodegenerative disorders; however, no genetically-inherited pathogenic mutations in any of the core autophagy-related (ATG) genes have been reported in human patients to date. We identified a homozygous missense mutation, changing a conserved amino acid, in ATG5 in two siblings with congenital ataxia, mental retardation, and developmental delay. The subjects' cells display a decrease in autophagy flux and defects in conjugation of ATG12 to ATG5. The homologous mutation in yeast demonstrates a 30-50% reduction of induced autophagy. Flies in which Atg5 is substituted with the mutant human ATG5 exhibit severe movement disorder, in contrast to flies expressing the wild-type human protein. Our results demonstrate the critical role of autophagy in preventing neurological diseases and maintaining neuronal health. PMID:26812546

  7. Autophagy is essential for effector CD8 T cell survival and memory formation

    PubMed Central

    Xu, Xiaojin; Araki, Koichi; Li, Shuzhao; Han, Jin-Hwan; Ye, Lilin; Tan, Wendy G.; Konieczny, Bogumila T.; Bruinsma, Monique W.; Martinez, Jennifer; Pearce, Erika L; Green, Douglas R.; Jones, Dean P.; Virgin, Herbert W.; Ahmed, Rafi

    2014-01-01

    The importance of autophagy in memory CD8 T cell differentiation in vivo is not well defined. We show here that autophagy is dynamically regulated in virus-specific CD8 T cells during acute lymphocytic choriomeningitis virus infection. Autophagy decreased in activated proliferating T cells, and was then upregulated at the peak of the effector T cell response. Consistent with this model, deletion of the key autophagy genes Atg7 or Atg5 in virus-specific CD8 T cells had minimal effect on generating effector cells but greatly enhanced their death during the contraction phase resulting in compromised memory formation. These findings provide insight into when autophagy is needed during effector and memory T cell differentiation in vivo and also warrant a re-examination of our current concepts about the relationship between T cell activation and autophagy. PMID:25362489

  8. Arginine vasopressin neuronal loss results from autophagy-associated cell death in a mouse model for familial neurohypophysial diabetes insipidus.

    PubMed

    Hagiwara, D; Arima, H; Morishita, Y; Wenjun, L; Azuma, Y; Ito, Y; Suga, H; Goto, M; Banno, R; Sugimura, Y; Shiota, A; Asai, N; Takahashi, M; Oiso, Y

    2014-01-01

    Familial neurohypophysial diabetes insipidus (FNDI) characterized by progressive polyuria is mostly caused by mutations in the gene encoding neurophysin II (NPII), which is the carrier protein of the antidiuretic hormone, arginine vasopressin (AVP). Although accumulation of mutant NPII in the endoplasmic reticulum (ER) could be toxic for AVP neurons, the precise mechanisms of cell death of AVP neurons, reported in autopsy studies, remain unclear. Here, we subjected FNDI model mice to intermittent water deprivation (WD) in order to promote the phenotypes. Electron microscopic analyses demonstrated that, while aggregates are confined to a certain compartment of the ER in the AVP neurons of FNDI mice with water access ad libitum, they were scattered throughout the dilated ER lumen in the FNDI mice subjected to WD for 4 weeks. It is also demonstrated that phagophores, the autophagosome precursors, emerged in the vicinity of aggregates and engulfed the ER containing scattered aggregates. Immunohistochemical analyses revealed that expression of p62, an adapter protein between ubiquitin and autophagosome, was elicited on autophagosomal membranes in the AVP neurons, suggesting selective autophagy induction at this time point. Treatment of hypothalamic explants of green fluorescent protein (GFP)-microtubule-associated protein 1 light chain 3 (LC3) transgenic mice with an ER stressor thapsigargin increased the number of GFP-LC3 puncta, suggesting that ER stress could induce autophagosome formation in the hypothalamus of wild-type mice as well. The cytoplasm of AVP neurons in FNDI mice was occupied with vacuoles in the mice subjected to WD for 12 weeks, when 30-40% of AVP neurons are lost. Our data thus demonstrated that autophagy was induced in the AVP neurons subjected to ER stress in FNDI mice. Although autophagy should primarily be protective for neurons, it is suggested that the organelles including ER were lost over time through autophagy, leading to autophagy

  9. Streptococcus pneumoniae induces pyroptosis through the regulation of autophagy in murine microglia.

    PubMed

    Kim, Ji-Yun; Paton, James C; Briles, David E; Rhee, Dong-Kwon; Pyo, Suhkneung

    2015-12-29

    Streptococcus pneumoniae is responsible for significant mortality and morbidity worldwide and causes invasive pneumococcal diseases including pneumococcal meningitis. Pyroptosis is caspase-1-dependent inflammatory cell death and is known to be induced by various microbial infections. In the present study, we investigated the molecular mechanisms that regulate pyroptosis induced by S. pneumoniae in microglia. Our results revealed that S. pneumoniae induced pyroptosis through caspase-1 activation and IL-1β production. We also found that the activation of caspase-1 and the maturation of IL-1β and IL-18 in the S. pneumoniae-triggered pyroptotic cell death process were mediated by NLRP3 inflammasome. In addition, pneumococcal infection increased the expression of autophagy-related genes and induced autophagosome formation. We also showed that the inhibition of autophagy promoted pneumococcus-induced pyroptosis. Furthermore, ROS was generated by pneumococcal infection and inhibited caspase-1 activation within 4 h of infection. However, in the late phase of infection, IL-1β secretion and caspase-1-dependent cell death were induced by ROS. These results suggest that autophagy induction transiently delay pyroptosis induced by S. pneumoniae in microglia. Our study also revealed that the activation of caspase-1 and the production of IL-1β were induced by pneumolysin and that pneumolysin triggered pyroptosis in microglial cells. Similar to the in vitro results, S. pneumoniae induced caspase-1 activation and caspase-1-dependent cytokine maturation in the mouse meningitis model. Thus, the present data demonstrate that S. pneumoniae induces pyroptosis in murine microglia and that NLRP3 inflammasome is critical for caspase-1 activation during the process. Furthermore, the induction of autophagy could transiently protect microglia from pyroptosis. PMID:26683708

  10. Streptococcus pneumoniae induces pyroptosis through the regulation of autophagy in murine microglia

    PubMed Central

    Kim, Ji-Yun; Paton, James C.; Briles, David E.; Rhee, Dong-Kwon; Pyo, Suhkneung

    2015-01-01

    Streptococcus pneumoniae is responsible for significant mortality and morbidity worldwide and causes invasive pneumococcal diseases including pneumococcal meningitis. Pyroptosis is caspase-1-dependent inflammatory cell death and is known to be induced by various microbial infections. In the present study, we investigated the molecular mechanisms that regulate pyroptosis induced by S. pneumoniae in microglia. Our results revealed that S. pneumoniae induced pyroptosis through caspase-1 activation and IL-1β production. We also found that the activation of caspase-1 and the maturation of IL-1β and IL-18 in the S. pneumoniae-triggered pyroptotic cell death process were mediated by NLRP3 inflammasome. In addition, pneumococcal infection increased the expression of autophagy-related genes and induced autophagosome formation. We also showed that the inhibition of autophagy promoted pneumococcus-induced pyroptosis. Furthermore, ROS was generated by pneumococcal infection and inhibited caspase-1 activation within 4 h of infection. However, in the late phase of infection, IL-1β secretion and caspase-1-dependent cell death were induced by ROS. These results suggest that autophagy induction transiently delay pyroptosis induced by S. pneumoniae in microglia. Our study also revealed that the activation of caspase-1 and the production of IL-1β were induced by pneumolysin and that pneumolysin triggered pyroptosis in microglial cells. Similar to the in vitro results, S. pneumoniae induced caspase-1 activation and caspase-1-dependent cytokine maturation in the mouse meningitis model. Thus, the present data demonstrate that S. pneumoniae induces pyroptosis in murine microglia and that NLRP3 inflammasome is critical for caspase-1 activation during the process. Furthermore, the induction of autophagy could transiently protect microglia from pyroptosis. PMID:26683708

  11. Cytoplastic Glyceraldehyde-3-Phosphate Dehydrogenases Interact with ATG3 to Negatively Regulate Autophagy and Immunity in Nicotiana benthamiana.

    PubMed

    Han, Shaojie; Wang, Yan; Zheng, Xiyin; Jia, Qi; Zhao, Jinping; Bai, Fan; Hong, Yiguo; Liu, Yule

    2015-04-01

    Autophagy as a conserved catabolic pathway can respond to reactive oxygen species (ROS) and plays an important role in degrading oxidized proteins in plants under various stress conditions. However, how ROS regulates autophagy in response to oxidative stresses is largely unknown. Here, we show that autophagy-related protein 3 (ATG3) interacts with the cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPCs) to regulate autophagy in Nicotiana benthamiana plants. We found that oxidative stress inhibits the interaction of ATG3 with GAPCs. Silencing of GAPCs significantly activates ATG3-dependent autophagy, while overexpression of GAPCs suppresses autophagy in N. benthamiana plants. Moreover, silencing of GAPCs enhances N gene-mediated cell death and plant resistance against both incompatible pathogens Tobacco mosaic virus and Pseudomonas syringae pv tomato DC3000, as well as compatible pathogen P. syringae pv tabaci. These results indicate that GAPCs have multiple functions in the regulation of autophagy, hypersensitive response, and plant innate immunity. PMID:25829441

  12. Cytoplastic Glyceraldehyde-3-Phosphate Dehydrogenases Interact with ATG3 to Negatively Regulate Autophagy and Immunity in Nicotiana benthamiana

    PubMed Central

    Han, Shaojie; Wang, Yan; Zheng, Xiyin; Jia, Qi; Zhao, Jinping; Bai, Fan; Hong, Yiguo; Liu, Yule

    2015-01-01

    Autophagy as a conserved catabolic pathway can respond to reactive oxygen species (ROS) and plays an important role in degrading oxidized proteins in plants under various stress conditions. However, how ROS regulates autophagy in response to oxidative stresses is largely unknown. Here, we show that autophagy-related protein 3 (ATG3) interacts with the cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPCs) to regulate autophagy in Nicotiana benthamiana plants. We found that oxidative stress inhibits the interaction of ATG3 with GAPCs. Silencing of GAPCs significantly activates ATG3-dependent autophagy, while overexpression of GAPCs suppresses autophagy in N. benthamiana plants. Moreover, silencing of GAPCs enhances N gene-mediated cell death and plant resistance against both incompatible pathogens Tobacco mosaic virus and Pseudomonas syringae pv tomato DC3000, as well as compatible pathogen P. syringae pv tabaci. These results indicate that GAPCs have multiple functions in the regulation of autophagy, hypersensitive response, and plant innate immunity. PMID:25829441

  13. Identification of genes that mediate protection against soybean pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the last twenty years, over 40 resistance genes (R-genes) have been cloned and characterized from plants. Of these, only three have been cloned in soybean. Cloning of resistance genes in soybean has been hampered by a complex, duplicated genome, clustering of R-genes, and lack of tools to charac...

  14. Ursolic acid enhances macrophage autophagy and attenuates atherogenesis.

    PubMed

    Leng, Shuilong; Iwanowycz, Stephen; Saaoud, Fatma; Wang, Junfeng; Wang, Yuzhen; Sergin, Ismail; Razani, Babak; Fan, Daping

    2016-06-01

    Macrophage autophagy has been shown to be protective against atherosclerosis. We previously discovered that ursolic acid (UA) promoted cancer cell autophagy. In the present study, we aimed to examine whether UA enhances macrophage autophagy in the context of atherogenesis. Cell culture study showed that UA enhanced autophagy of macrophages by increasing the expression of Atg5 and Atg16l1, which led to altered macrophage function. UA reduced pro-interleukin (IL)-1β protein levels and mature IL-1β secretion in macrophages in response to lipopolysaccharide (LPS), without reducing IL-1β mRNA expression. Confocal microscopy showed that in LPS-treated macrophages, UA increased LC3 protein levels and LC3 appeared to colocalize with IL-1β. In cholesterol-loaded macrophages, UA increased cholesterol efflux to apoAI, although it did not alter mRNA or protein levels of ABCA1 and ABCG1. Electron microscopy showed that UA induced lipophagy in acetylated LDL-loaded macrophages, which may result in increased cholesterol ester hydrolysis in autophagolysosomes and presentation of free cholesterol to the cell membrane. In LDLR(-/-) mice fed a Western diet to induce atherogenesis, UA treatment significantly reduced atherosclerotic lesion size, accompanied by increased macrophage autophagy. In conclusion, the data suggest that UA promotes macrophage autophagy and, thereby, suppresses IL-1β secretion, promotes cholesterol efflux, and attenuates atherosclerosis in mice. PMID:27063951

  15. Cytoplasmic sphingosine-1-phosphate pathway modulates neuronal autophagy

    PubMed Central

    Moruno Manchon, Jose Felix; Uzor, Ndidi-Ese; Dabaghian, Yuri; Furr-Stimming, Erin E.; Finkbeiner, Steven; Tsvetkov, Andrey S.

    2015-01-01

    Autophagy is an important homeostatic mechanism that eliminates long-lived proteins, protein aggregates and damaged organelles. Its dysregulation is involved in many neurodegenerative disorders. Autophagy is therefore a promising target for blunting neurodegeneration. We searched for novel autophagic pathways in primary neurons and identified the cytosolic sphingosine-1-phosphate (S1P) pathway as a regulator of neuronal autophagy. S1P, a bioactive lipid generated by sphingosine kinase 1 (SK1) in the cytoplasm, is implicated in cell survival. We found that SK1 enhances flux through autophagy and that S1P-metabolizing enzymes decrease this flux. When autophagy is stimulated, SK1 relocalizes to endosomes/autophagosomes in neurons. Expression of a dominant-negative form of SK1 inhibits autophagosome synthesis. In a neuron model of Huntington’s disease, pharmacologically inhibiting S1P-lyase protected neurons from mutant huntingtin-induced neurotoxicity. These results identify the S1P pathway as a novel regulator of neuronal autophagy and provide a new target for developing therapies for neurodegenerative disorders. PMID:26477494

  16. IKKβ/NFκBp65 activated by interleukin-13 targets the autophagy-related genes LC3B and beclin 1 in fibroblasts co-cultured with breast cancer cells

    PubMed Central

    LI, WEN-LIN; XIONG, LI-XIA; SHI, XIAO-YU; XIAO, LIANG; QI, GUAN-YUN; MENG, CHUANG

    2016-01-01

    Interleukin-13 (IL-13), a Th2 cytokine, plays an important role in fibrosis, inflammation, tissue hyperresponsiveness and tumor development. Although studies have demonstrated that IL-13 exerts its roles through signal transducer and activator of transcription 6 (STAT6) signaling pathway, recent studies have revealed that I kappa B kinase (IKK)/nuclear factor kappa B (NFκB) pathway may also be involved in. The aim of this study was to investigate whether IL-13 delivers signals to IKKβ/NFκBp65 and whether autophagy genes are IL-13-induced the activation of NFκBp65 transcriptional targets in fibroblasts of breast tumor stroma. We examined the phosphorylation of IKKβ, the activation of NFκBp65 and NFκBp65-targeted autophagy genes in fibroblasts co-cultured with breast cancer cells under the condition of IL-13 stimulation. Results of this study showed that IL-13 induced IKKβ phosphorylation in the fibroblast line ESF co-cultured with breast cancer cell line BT474, and subsequently NFκBp65 was activated and aimed at beclin 1 and microtubule-associated protein 1 light chain 3 B (MAP1LC3B or LC3B) in these ESF cells. BMS345541, an inhibitor of IKK/NFκB pathway, significantly inhibited the IL-13-induced the activation of NFκB and also inhibited NFκB-targeted beclin 1 and LC3B expression. Our results suggest that IL-13 regulates beclin 1 and LC3B expression through IKKβ/NFκBp65 in fibroblasts co-cultured with breast cancer cells, and IL-13 plays role in activating IKKβ/NFκBp65. PMID:27073433

  17. Thyroid Hormone Stimulation of Autophagy Is Essential for Mitochondrial Biogenesis and Activity in Skeletal Muscle.

    PubMed

    Lesmana, Ronny; Sinha, Rohit A; Singh, Brijesh K; Zhou, Jin; Ohba, Kenji; Wu, Yajun; Yau, Winifred W Y; Bay, Boon-Huat; Yen, Paul M

    2016-01-01

    Thyroid hormone (TH) and autophagy share similar functions in regulating skeletal muscle growth, regeneration, and differentiation. Although TH recently has been shown to increase autophagy in liver, the regulation and role of autophagy by this hormone in skeletal muscle is not known. Here, using both in vitro and in vivo models, we demonstrated that TH induces autophagy in a dose- and time-dependent manner in skeletal muscle. TH induction of autophagy involved reactive oxygen species (ROS) stimulation of 5'adenosine monophosphate-activated protein kinase (AMPK)-Mammalian target of rapamycin (mTOR)-Unc-51-like kinase 1 (Ulk1) signaling. TH also increased mRNA and protein expression of key autophagy genes, microtubule-associated protein light chain 3 (LC3), Sequestosome 1 (p62), and Ulk1, as well as genes that modulated autophagy and Forkhead box O (FOXO) 1/3a. TH increased mitochondrial protein synthesis and number as well as basal mitochondrial O2 consumption, ATP turnover, and maximal respiratory capacity. Surprisingly, mitochondrial activity and biogenesis were blunted when autophagy was blocked in muscle cells by Autophagy-related gene (Atg)5 short hairpin RNA (shRNA). Induction of ROS and 5'adenosine monophosphate-activated protein kinase (AMPK) by TH played a significant role in the up-regulation of Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A), the key regulator of mitochondrial synthesis. In summary, our findings showed that TH-mediated autophagy was essential for stimulation of mitochondrial biogenesis and activity in skeletal muscle. Moreover, autophagy and mitochondrial biogenesis were coupled in skeletal muscle via TH induction of mitochondrial activity and ROS generation. PMID:26562261

  18. Roles of Autophagy Induced by Natural Compounds in Prostate Cancer

    PubMed Central

    Naponelli, V.; Bettuzzi, S.

    2015-01-01

    Autophagy is a homeostatic mechanism through which intracellular organelles and proteins are degraded and recycled in response to increased metabolic demand or stress. Autophagy dysfunction is often associated with many diseases, including cancer. Because of its role in tumorigenesis, autophagy can represent a new therapeutic target for cancer treatment. Prostate cancer (PCa) is one of the most common cancers in aged men. The evidence on alterations of autophagy related genes and/or protein levels in PCa cells suggests a potential implication of autophagy in PCa onset and progression. The use of natural compounds, characterized by low toxicity to normal tissue associated with specific anticancer effects at physiological levels in vivo, is receiving increasing attention for prevention and/or treatment of PCa. Understanding the mechanism of action of these compounds could be crucial for the development of new therapeutic or chemopreventive options. In this review we focus on the current evidence showing the capacity of natural compounds to exert their action through autophagy modulation in PCa cells. PMID:25821782

  19. Regulation of the autophagy protein LC3 by phosphorylation

    PubMed Central

    Cherra, Salvatore J.; Kulich, Scott M.; Uechi, Guy; Balasubramani, Manimalha; Mountzouris, John; Day, Billy W.

    2010-01-01

    Macroautophagy is a major catabolic pathway that impacts cell survival, differentiation, tumorigenesis, and neurodegeneration. Although bulk degradation sustains carbon sources during starvation, autophagy contributes to shrinkage of differentiated neuronal processes. Identification of autophagy-related genes has spurred rapid advances in understanding the recruitment of microtubule-associated protein 1 light chain 3 (LC3) in autophagy induction, although braking mechanisms remain less understood. Using mass spectrometry, we identified a direct protein kinase A (PKA) phosphorylation site on LC3 that regulates its participation in autophagy. Both metabolic (rapamycin) and pathological (MPP+) inducers of autophagy caused dephosphorylation of endogenous LC3. The pseudophosphorylated LC3 mutant showed reduced recruitment to autophagosomes, whereas the nonphosphorylatable mutant exhibited enhanced puncta formation. Finally, autophagy-dependent neurite shortening induced by expression of a Parkinson disease–associated G2019S mutation in leucine-rich repeat kinase 2 was inhibited by dibutyryl–cyclic adenosine monophosphate, cytoplasmic expression of the PKA catalytic subunit, or the LC3 phosphorylation mimic. These data demonstrate a role for phosphorylation in regulating LC3 activity. PMID:20713600

  20. Blockage of autophagy pathway enhances Salmonella tumor-targeting

    PubMed Central

    Dong, Tiangeng; Zhao, Ming; Wu, Jianfu; Li, Lihui; Chu, Yiwei; She, Shangyang; Zhao, Hu; Hoffman, Robert M.; Jia, Lijun

    2016-01-01

    Previous studies have shown that strains of Salmonella typhimurium specifically target tumors in mouse models of cancer. In this study, we report that tumor-targeting Salmonella typhimurium A1-R (A1-R) or VNP20009 induced autophagy in human cancer cells, which serves as a defense response. Functionally, by knockdown of essential autophagy genes Atg5 or Beclin1 in bacteria-infected cancer cells, the autophagy pathway was blocked, which led to a significant increase of intracellular bacteria multiplication in cancer cells. Genetic inactivation of the autophagy pathway enhanced A1-R or VNP20009-mediated cancer cell killing by increasing apoptotic activity. We also demonstrate that the combination of pharmacological autophagy inhibitors chloroquine (CQ) or bafilomycin A1 (Baf A1) with tumor-targeting A1-R or VNP20009 significantly enhanced cancer-cell killing compared with Salmonella infection alone. These findings provide a proof-of-concept of combining autophagy inhibitors and tumor-targeting Salmonella to enhance cancer-cell killing. PMID:27013582

  1. The Role of Autophagy in Hepatocellular Carcinoma

    PubMed Central

    Lee, Yoo Jin; Jang, Byoung Kuk

    2015-01-01

    Autophagy is a catabolic process involved in cellular homeostasis under basal and stressed conditions. Autophagy is crucial for normal liver physiology and the pathogenesis of liver diseases. During the last decade, the function of autophagy in hepatocellular carcinoma (HCC) has been evaluated extensively. Currently, autophagy is thought to play a dual role in HCC, i.e., autophagy is involved in tumorigenesis and tumor suppression. Recent investigations of autophagy have suggested that autophagy biomarkers can facilitate HCC prognosis and the establishment of therapeutic approaches. In this review, we briefly summarize the current understanding of autophagy and discuss recent evidence for its role in HCC. PMID:26561802

  2. The Role of Autophagy in Hepatocellular Carcinoma.

    PubMed

    Lee, Yoo Jin; Jang, Byoung Kuk

    2015-01-01

    Autophagy is a catabolic process involved in cellular homeostasis under basal and stressed conditions. Autophagy is crucial for normal liver physiology and the pathogenesis of liver diseases. During the last decade, the function of autophagy in hepatocellular carcinoma (HCC) has been evaluated extensively. Currently, autophagy is thought to play a dual role in HCC, i.e., autophagy is involved in tumorigenesis and tumor suppression. Recent investigations of autophagy have suggested that autophagy biomarkers can facilitate HCC prognosis and the establishment of therapeutic approaches. In this review, we briefly summarize the current understanding of autophagy and discuss recent evidence for its role in HCC. PMID:26561802

  3. Clinical application: Restoration of immune homeostasis by autophagy as a potential therapeutic target in sepsis

    PubMed Central

    ZHANG, LEMENG; AI, YUHANG; TSUNG, ALLAN

    2016-01-01

    Sepsis-induced lymphocyte and dendritic cell apoptosis contributes to immunosuppression, resulting in an inability to eradicate the primary infection and a propensity to acquire secondary infections. However, the inhibition of apoptosis may produce unexpected and undesirable consequences. Another cellular process, autophagy, is also activated in immune cells. There is increasing evidence to suggest that autophagy confers a protective effect in sepsis. The protective mechanisms underlying this effect include limiting apoptotic cell death and maintaining cellular homeostasis. Therefore, understanding the regulation of immune cell autophagy and apoptosis may provide insight into novel therapeutic strategies. The present review examined potential novel therapeutic strategies aimed at restoring immune homeostasis by inducing autophagy. The restoration of balance between apoptosis and autophagy may be a novel approach for improving sepsis-induced immunosuppression and decreasing susceptibility to sepsis. PMID:27073416

  4. Mirror image phosphoinositides regulate autophagy

    PubMed Central

    Vicinanza, Mariella; Rubinsztein, David C

    2016-01-01

    Autophagosome formation is stimulated by canonical VPS34-dependent formation of phosphatidylinositol 3-phosphate [PI(3)P], which recruits effectors such as WIPI2. However, non-canonical VPS34-independent autophagy has also been proposed. We recently described that PI(5)P regulates autophagosome biogenesis, recruits WIPI2, and rescues autophagy in VPS34-inactivated cells. These alternative autophagy-initiating pathways reveal new druggable targets for treating neurodegeneration and cancer. PMID:27308581

  5. Spermidine and resveratrol induce autophagy by distinct pathways converging on the acetylproteome

    PubMed Central

    Morselli, Eugenia; Mariño, Guillermo; Bennetzen, Martin V.; Eisenberg, Tobias; Megalou, Evgenia; Schroeder, Sabrina; Cabrera, Sandra; Bénit, Paule; Rustin, Pierre; Criollo, Alfredo; Kepp, Oliver; Galluzzi, Lorenzo; Shen, Shensi; Malik, Shoaib Ahmad; Maiuri, Maria Chiara; Horio, Yoshiyuki; López-Otín, Carlos; Andersen, Jens S.; Tavernarakis, Nektarios

    2011-01-01

    Autophagy protects organelles, cells, and organisms against several stress conditions. Induction of autophagy by resveratrol requires the nicotinamide adenine dinucleotide–dependent deacetylase sirtuin 1 (SIRT1). In this paper, we show that the acetylase inhibitor spermidine stimulates autophagy independent of SIRT1 in human and yeast cells as well as in nematodes. Although resveratrol and spermidine ignite autophagy through distinct mechanisms, these compounds stimulate convergent pathways that culminate in concordant modifications of the acetylproteome. Both agents favor convergent deacetylation and acetylation reactions in the cytosol and in the nucleus, respectively. Both resveratrol and spermidine were able to induce autophagy in cytoplasts (enucleated cells). Moreover, a cytoplasm-restricted mutant of SIRT1 could stimulate autophagy, suggesting that cytoplasmic deacetylation reactions dictate the autophagic cascade. At doses at which neither resveratrol nor spermidine stimulated autophagy alone, these agents synergistically induced autophagy. Altogether, these data underscore the importance of an autophagy regulatory network of antagonistic deacetylases and acetylases that can be pharmacologically manipulated. PMID:21339330

  6. The interplay between autophagy and apoptosis induced by tanshinone IIA in prostate cancer cells.

    PubMed

    Li, Chunlong; Han, Xiancheng; Zhang, Hong; Wu, Jinsheng; Li, Bao

    2016-06-01

    Tanshinone IIA (T2A), a derivative of phenanthrenequinone and also the major active ingredient of Danshen, has been paid extensive attention as a promising cancer therapy for its potential anti-cancer activities. In this study, the apoptosis and autophagy of human prostate cancer PC-3 cells were observed after 5 μM T2A treatment, as well as their relevance. Mitochondrial-dependent apoptosis was firstly detected through morphological observation and biochemical analysis. Meanwhile, 5 μM T2A successfully triggered the autophagy of PC-3 cells, indicated by increased expression of Beclin1, and LC3 II. Validation experiments were conducted to further consolidate T2A's contribution to autophagy: Pretreatment with autophagy inhibitor 3-methyladenine (3-MA) provided protection against autophagy and enhanced T2A-induced apoptosis. Besides, the apoptosis suppressor z-VAD-fmk failed to facilitate the formation of autophagic vacuoles, which also proved the T2A-induced autophagy independent of apoptosis. Moreover, the reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) efficiently inhibited the expression of Beclin1, LC3-II, and cleaved caspase-3, which indicated apoptosis and autophagy with dependence on intracellular ROS production. Taken together, these results demonstrated that autophagy is the cytoprotective mechanism in this experimental system, and the ROS resulted from T2A treatment played a critical role in apoptosis and autophagy initiation. PMID:26687918

  7. Targeting autophagy in neurodegenerative diseases.

    PubMed

    Vidal, René L; Matus, Soledad; Bargsted, Leslie; Hetz, Claudio

    2014-11-01

    The most prevalent neurodegenerative disorders involve protein misfolding and the aggregation of specific proteins. Autophagy is becoming an attractive target to treat neurodegenerative disorders through the selective degradation of abnormally folded proteins by the lysosomal pathway. However, accumulating evidence indicates that autophagy impairment at different regulatory steps may contribute to the neurodegenerative process. Thus, a complex scenario is emerging where autophagy may play a dual role in neurodegenerative diseases by causing the downstream effect of promoting the degradation of misfolded proteins and an upstream effect where its deregulation perturbs global proteostasis, contributing to disease progression. Challenges in the future development of therapeutic strategies to target the autophagy pathway are discussed. PMID:25270767

  8. Inhibition of autophagy promotes apoptosis and enhances anticancer efficacy of adriamycin via augmented ROS generation in prostate cancer cells.

    PubMed

    Wang, Jizhong; Tan, Xiangpeng; Yang, Qi; Zeng, Xiangfeng; Zhou, Yuying; Luo, Wu; Lin, Xiaomian; Song, Li; Cai, Jialong; Wang, Tianxiang; Wu, Xiaoping

    2016-08-01

    The interplay between autophagy and apoptosis response to chemotherapy is still a subject of intense debate in recent years. More efforts have focused on the regulation effects of apoptosis on autophagy, whereas how autophagy affects apoptosis remains poorly understood. In this study performed on prostate cancer cells, we investigated the role of autophagy in adriamycin-induced apoptosis, as well as the mechanisms mediating the effects of autophagy on apoptosis response to adriamycin (ADM). The results show that ADM not only inhibited cell viability and enhanced apoptosis, but also promoted autophagy via PI3K/Akt(T308)/mTOR signal pathway. Inhibition of autophagy by either pharmacological inhibitor chloroquine (CQ) or RNA interference of Atg5 increased ADM-induced apoptosis and enhanced the chemosensitivity of prostate cancer cells. Moreover, blockade of autophagy augmented reactive oxygen species (ROS) generation induced by ADM. Scavenging of ROS by antioxidant N-acetyl-cysteine (NAC) reversed the strengthened effects of CQ on ADM-induced apoptosis and rescued the cells from apoptosis. The results identified ROS as a potential mediator directing the modulation effects of the protective autophagy on apoptosis response to ADM. Suppression of the protective autophagy might provide a promising strategy to increase the anticancer efficacy of agents in the treatment of prostate cancer. PMID:27247025

  9. Autophagy inhibition radiosensitizes in vitro, yet reduces radioresponses in vivo due to deficient immunogenic signalling.

    PubMed

    Ko, A; Kanehisa, A; Martins, I; Senovilla, L; Chargari, C; Dugue, D; Mariño, G; Kepp, O; Michaud, M; Perfettini, J-L; Kroemer, G; Deutsch, E

    2014-01-01

    Clinical oncology heavily relies on the use of radiotherapy, which often leads to merely transient responses that are followed by local or distant relapse. The molecular mechanisms explaining radioresistance are largely elusive. Here, we identified a dual role of autophagy in the response of cancer cells to ionizing radiation. On one hand, we observed that the depletion of essential autophagy-relevant gene products, such as ATG5 and Beclin 1, increased the sensitivity of human or mouse cancer cell lines to irradiation, both in vitro (where autophagy inhibition increased radiation-induced cell death and decreased clonogenic survival) and in vivo, after transplantation of the cell lines into immunodeficient mice (where autophagy inhibition potentiated the tumour growth-inhibitory effect of radiotherapy). On the other hand, when tumour proficient or deficient for autophagy were implanted in immunocompetent mice, it turned out that defective autophagy reduced the efficacy of radiotherapy. Indeed, radiotherapy elicited an anti-cancer immune response that was dependent on autophagy-induced ATP release from stressed or dying tumour cells and was characterized by dense lymphocyte infiltration of the tumour bed. Intratumoural injection of an ecto-ATPase inhibitor restored the immune infiltration of autophagy-deficient tumours post radiotherapy and improved the growth-inhibitory effect of ionizing irradiation. Altogether, our results reveal that beyond its cytoprotective function, autophagy confers immunogenic properties to tumours, hence amplifying the efficacy of radiotherapy in an immunocompetent context. This has far-reaching implications for the development of pharmacological radiosensitizers. PMID:24037090

  10. Measurements of tumor cell autophagy predict invasiveness, resistance to chemotherapy, and survival in melanoma

    PubMed Central

    Ma, Xiaohong; Piao, Shengfu; Wang, Dan; Mcafee, Quentin; Nathanson, Katherine L.; Lum, Julian J.; Li, Lin Z.; Amaravadi, Ravi K.

    2011-01-01

    Purpose Autophagy consists of lysosome-dependent degradation of cytoplasmic contents sequestered by autophagic vesicles (AV). The role of autophagy in determining tumor aggressiveness and response to therapy in melanoma was investigated in this study. Experimental Design Autophagy was measured in tumor biopsies obtained from metastatic melanoma patients enrolled on a phase II trial of temozolomide and sorafenib and correlated to clinical outcome. These results were compared to autophagy measurements in aggressive and indolent melanoma cells grown in two and three dimensional culture and as xenograft tumors. The effects of autophagy inhibition with either hydroxychloroquine or inducible shRNA against the autophagy gene ATG5 were assessed in three dimensional spheroids. Results Patients whose tumors had a high autophagic index were less likely to respond to treatment and had a shorter survival compared to those with a low autophagic index. Differences in autophagy were less evident in aggressive and indolent melanoma cells grown in monolayer culture. In contrast, autophagy was increased in aggressive compared to indolent melanoma xenograft tumors. This difference was recapitulated when aggressive and indolent melanoma cells were grown as spheroids. Autophagy inhibition with either hydroxychloroquine or inducible shRNA against ATG5 resulted in cell death in aggressive melanoma spheroids, and significantly augmented temozolomide-induced cell death. Conclusions Autophagy is a potential prognostic factor and therapeutic target in melanoma. Three dimensional culture mimics the tumor microenvironment better than monolayer culture and is an appropriate model for studying therapeutic combinations involving autophagy modulators autophagy inhibition should be tested clinically in patients with melanoma. PMID:21325076

  11. Dual functions of autophagy in the response of breast tumor cells to radiation

    PubMed Central

    Bristol, Molly L.; Di, Xu; Beckman, Matthew J.; Wilson, Eden N.; Henderson, Scott C.; Maiti, Aparna; Fan, Zhen; Gewirtz, David A.

    2012-01-01

    In MCF-7 breast tumor cells, ionizing radiation promoted autophagy that was cytoprotective; pharmacological or genetic interference with autophagy induced by radiation resulted in growth suppression and/or cell killing (primarily by apoptosis). The hormonally active form of vitamin D, 1,25D3, also promoted autophagy in irradiated MCF-7 cells, sensitized the cells to radiation and suppressed the proliferative recovery that occurs after radiation alone. 1,25D3 enhanced radiosensitivity and promoted autophagy in MCF-7 cells that overexpress Her-2/neu as well as in p53 mutant Hs578t breast tumor cells. In contrast, 1,25D3 failed to alter radiosensitivity or promote autophagy in the BT474 breast tumor cell line with low-level expression of the vitamin D receptor. Enhancement of MCF-7 cell sensitivity to radiation by 1,25D3 was not attenuated by a genetic block to autophagy due largely to the promotion of apoptosis via the collateral suppression of protective autophagy. However, MCF-7 cells were protected from the combination of 1,25D3 with radiation using a concentration of chloroquine that produced minimal sensitization to radiation alone. The current studies are consistent with the premise that while autophagy mediates a cytoprotective function in irradiated breast tumor cells, promotion of autophagy can also confer radiosensitivity by vitamin D (1,25D3). As both cytoprotective and cytotoxic autophagy can apparently be expressed in the same experimental system in response to radiation, this type of model could be utilized to distinguish biochemical, molecular and/or functional differences in these dual functions of autophagy. PMID:22498493

  12. Autophagy in cardiovascular biology

    PubMed Central

    Lavandero, Sergio; Chiong, Mario; Rothermel, Beverly A.; Hill, Joseph A.

    2015-01-01

    Cardiovascular disease is the leading cause of death worldwide. As such, there is great interest in identifying novel mechanisms that govern the cardiovascular response to disease-related stress. First described in failing hearts, autophagy within the cardiovascular system has been widely characterized in cardiomyocytes, cardiac fibroblasts, endothelial cells, vascular smooth muscle cells, and macrophages. In all cases, a window of optimal autophagic activity appears to be critical to the maintenance of cardiovascular homeostasis and function; excessive or insufficient levels of autophagic flux can each contribute to heart disease pathogenesis. In this Review, we discuss the potential for targeting autophagy therapeutically and our vision for where this exciting biology may lead in the future. PMID:25654551

  13. Myosins, Actin and Autophagy.

    PubMed

    Kruppa, Antonina J; Kendrick-Jones, John; Buss, Folma

    2016-08-01

    Myosin motor proteins working together with the actin cytoskeleton drive a wide range of cellular processes. In this review, we focus on their roles in autophagy - the pathway the cell uses to ensure homeostasis by targeting pathogens, misfolded proteins and damaged organelles for degradation. The actin cytoskeleton regulated by a host of nucleating, anchoring and stabilizing proteins provides the filament network for the delivery of essential membrane vesicles from different cellular compartments to the autophagosome. Actin networks have also been implicated in structurally supporting the expanding phagophore, moving autophagosomes and enabling efficient fusion with the lysosome. Only a few myosins have so far been shown to play a role in autophagy. Non-muscle myosin IIA functions in the early stages delivering membrane for the initial formation of the autophagosome, whereas myosin IC and myosin VI are involved in the final stages providing specific membranes for autophagosome maturation and its fusion with the lysosome. PMID:27146966

  14. Autophagy: An Integral Component of the Mammalian Stress Response

    PubMed Central

    Ryter, Stefan W.; Choi, Augustine M. K.

    2013-01-01

    Mammalian cells and tissues respond to chemical and physical stress by inducing adaptive or protective mechanisms that prolong survival. Among these, the major stress inducible proteins (heat shock proteins, glucose regulated proteins, heme oxygenase-1) provide cellular protection through protein chaperone and/or anti-oxidative and anti-inflammatory functions. In recent years it has become clear that autophagy, a genetically-programmed and evolutionarily-conserved cellular process represents another adaptive response to cellular stress. During autophagy cytosolic material, including organelles, proteins, and foreign pathogens, are sequestered into membrane-bound vesicles termed autophagosomes, and then delivered to the lysosome for degradation. Through recycling of cellular biochemicals, autophagy provides a mechanism for adaptation to starvation. Recent research has uncovered selective autophagic pathways that target distinct cargoes to autophagosomes, including mechanisms for the clearance of aggregated protein, and for the removal of dysfunctional mitochondria (mitophagy). Autophagy can be induced by multiple forms of chemical and physical stress, including endoplasmic reticulum stress and oxidative stress, and plays an integral role in the mammalian stress response. Understanding of the interaction and co-regulation of autophagy with other stress-inducible systems will be useful in the design and implementation of therapeutics targeting this pathway. PMID:24358454

  15. C1q/TNF-Related Protein 9 (CTRP9) attenuates hepatic steatosis via the autophagy-mediated inhibition of endoplasmic reticulum stress.

    PubMed

    Jung, Tae Woo; Hong, Ho Cheol; Hwang, Hwan-Jin; Yoo, Hye Jin; Baik, Sei Hyun; Choi, Kyung Mook

    2015-12-01

    C1q/TNF-Related Protein (CTRP) 9, the closest paralog of adiponectin, has been reported to protect against diet-induced obesity and non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanism has not been fully elucidated. We explored the protective effect of CTRP9 against hepatic steatosis and apoptosis, and identified the mechanisms through autophagy and endoplasmic reticulum (ER) stress using in vitro and in vivo experiments. Treating HepG2 cells with human recombinant CTRP9 significantly ameliorated palmitate- or tunicamycin-induced dysregulation of lipid metabolism, caspase 3 activity and chromatin condensation, which lead to reduction of hepatic triglyceride (TG) accumulation. CTRP9 treatment induced autophagy markers including LC3 conversion, P62 degradation, Beclin1 and ATG7 through AMPK phosphorylation in human primary hepatocytes. Furthermore, CTRP9 decreased palmitate- or tunicamycin-induced ER stress markers, such as eIF2α, CHOP and IRE-1, in HepG2 cells. Compound C, an AMPK inhibitor, and 3 methyladenine (3 MA), an autophagy inhibitor, canceled the effects of CTRP9 on ER stress, apoptosis and hepatic steatosis. In the livers of HFD-fed mice, adenovirus-mediated CTRP9 overexpression significantly induced AMPK phosphorylation and autophagy, whereas suppressed ER stress markers. In addition, both SREBP1-mediated lipogenic gene expression and apoptosis were significantly attenuated, which result in improvement in hepatic steatosis by overexpression of CTRP9. These results demonstrate that CTRP9 alleviates hepatic steatosis through relief of ER stress via the AMPK-mediated induction of autophagy. PMID:26419929

  16. Autophagy in dementias.

    PubMed

    Kragh, Christine Lund; Ubhi, Kiren; Wyss-Coray, Tony; Wyss-Corey, Tony; Masliah, Eliezer

    2012-01-01

    Dementias are a varied group of disorders typically associated with memory loss, impaired judgment and/or language and by symptoms affecting other cognitive and social abilities to a degree that interferes with daily functioning. Alzheimer's disease (AD) is the most common cause of a progressive dementia, followed by dementia with Lewy bodies (DLB), frontotemporal dementia (FTD), (VaD) and HIV-associated neurocognitive disorders (HAND). The pathogenesis of this group of disorders has been linked to the abnormal accumulation of proteins in the brains of affected individuals, which in turn has been related to deficits in protein clearance. Autophagy is a key cellular protein clearance pathway with proteolytic cleavage and degradation via the ubiquitin-proteasome pathway representing another important clearance mechanism. Alterations in the levels of autophagy and the proteins associated with the autophagocytic pathway have been reported in various types of dementias. This review will examine recent literature across these disorders and highlight a common theme of altered autophagy across the spectrum of the dementias. PMID:22150925

  17. Cholesterol depletion induces autophagy

    SciTech Connect

    Cheng, Jinglei; Ohsaki, Yuki; Tauchi-Sato, Kumi; Fujita, Akikazu; Fujimoto, Toyoshi . E-mail: tfujimot@med.nagoya-u.ac.jp

    2006-12-08

    Autophagy is a mechanism to digest cells' own components, and its importance in many physiological and pathological processes is being recognized. But the molecular mechanism that regulates autophagy is not understood in detail. In the present study, we found that cholesterol depletion induces macroautophagy. The cellular cholesterol in human fibroblasts was depleted either acutely using 5 mM methyl-{beta}-cyclodextrin or 10-20 {mu}g/ml nystatin for 1 h, or metabolically by 20 {mu}M mevastatin and 200 {mu}M mevalonolactone along with 10% lipoprotein-deficient serum for 2-3 days. By any of these protocols, marked increase of LC3-II was detected by immunoblotting and by immunofluorescence microscopy, and the increase was more extensive than that caused by amino acid starvation, i.e., incubation in Hanks' solution for several hours. The induction of autophagic vacuoles by cholesterol depletion was also observed in other cell types, and the LC3-positive membranes were often seen as long tubules, >50 {mu}m in length. The increase of LC3-II by methyl-{beta}-cyclodextrin was suppressed by phosphatidylinositol 3-kinase inhibitors and was accompanied by dephosphorylation of mammalian target of rapamycin. By electron microscopy, autophagic vacuoles induced by cholesterol depletion were indistinguishable from those seen after amino acid starvation. These results demonstrate that a decrease in cholesterol activates autophagy by a phosphatidylinositol 3-kinase-dependent mechanism.

  18. Autophagy on acid.

    PubMed

    Wojtkowiak, Jonathan W; Gillies, Robert J

    2012-11-01

    The microenvironment of solid tumors tends to be more acidic (6.5-7.0) than surrounding normal (7.2-7.4) tissue. Chaotic vasculature, oxygen limitation and major metabolic changes all contribute to the acidic microenvironment. We have previously proposed that low extracellular pH (pHe) plays a critical role in the development and progression of solid tumors. While extracellular acidosis is toxic to most normal cells, cancer cells can adapt and survive under this harsh condition. In this study, we focused on identifying survival strategies employed by cancer cells when challenged with an acidic pHe (6.6-6.7) either acutely or for many generations. While acutely acidic cells did not grow, those acclimated over many generations grew at the same rate as control cells. We observed that these cells induce autophagy in response to acidosis both acutely and chronically, and that this adaptation appears to be necessary for survival. Inhibition of autophagy in low pH cultured cells results in cell death. Histological analysis of tumor xenografts reveals a strong correlation of LC3 protein expression in regions projected to be acidic. Furthermore, in vivo buffering experiments using sodium bicarbonate, previously shown to raise extracellular tumor pH, decreases LC3 protein expression in tumor xenografts. These data imply that autophagy can be induced by extracellular acidosis and appears to be chronically employed as a survival adaptation to acidic microenvironments. PMID:22874557

  19. Activation of Pattern Recognition Receptors Upregulates Metallothioneins, Thereby Increasing Intracellular Accumulation of Zinc, Autophagy, and Bacterial Clearance by Macrophages

    PubMed Central

    Lahiri, Amit; Abraham, Clara

    2014-01-01

    Background & Aims Continuous stimulation of pattern recognition receptors (PRRs), including nucleotide-binding oligomerization domain-2 (NOD2) (variants in NOD2 have been associated with Crohn's disease), alters the phenotype of myeloid-derived cells, reducing production of inflammatory cytokines and increasing clearance of microbes. We investigated the mechanisms by which microbial clearance increases in macrophages under these conditions. METHODS Monocytes were purified from human peripheral blood mononuclear cells and differentiated to monocyte-derived macrophages (MDMs). We also isolated human intestinal macrophages. Bacterial clearance by MDMs was assessed in gentamicin protection assays. Effects of intracellular zinc and autophagy were measured by flow cytometry, immunoblot, reverse transcription PCR, and microscopy experiments. Small interfering RNAs were used to knock down specific proteins in MDMs. NOD2–/– and C57BL/6J mice, maintained in a specific pathogen-free facility, were given antibiotics, muramyl dipeptide (to stimulate NOD2), or dextran sodium sulfate; intestinal lamina propria cells were collected and analyzed. RESULTS Chronic stimulation of human MDMs through NOD2 upregulated the expression of multiple genes encoding metallothioneins, which bind and regulate levels of intracellular zinc. Intestinal myeloid-derived cells are continually stimulated through PRRs; metallothionein expression was upregulated in human and mouse intestinal myeloid-derived cells. Continuous stimulation of NOD2 increased levels of intracellular zinc, thereby increasing autophagy and bacterial clearance. The metal-regulatory transcription factor-1 (MTF-1) was required for regulation of metallothionein genes in human MDMs. Knockdown of MTF-1 did not affect baseline clearance of bacteria by MDMs. However, the increase in intracellular zinc, autophagy, and bacterial clearance observed with continuous NOD2 stimulation was impaired in MDMs upon MTF-1 knockdown. Addition of

  20. TAK1-mediated autophagy and fatty acid oxidation prevent hepatosteatosis and tumorigenesis

    PubMed Central

    Inokuchi-Shimizu, Sayaka; Park, Eek Joong; Roh, Yoon Seok; Yang, Ling; Zhang, Bi; Song, Jingyi; Liang, Shuang; Pimienta, Michael; Taniguchi, Koji; Wu, Xuefeng; Asahina, Kinji; Lagakos, William; Mackey, Mason R.; Akira, Shizuo; Ellisman, Mark H.; Sears, Dorothy D.; Olefsky, Jerrold M.; Karin, Michael; Brenner, David A.; Seki, Ekihiro

    2014-01-01

    The MAP kinase kinase kinase TGFβ-activated kinase 1 (TAK1) is activated by TLRs, IL-1, TNF, and TGFβ and in turn activates IKK-NF-κB and JNK, which regulate cell survival, growth, tumorigenesis, and metabolism. TAK1 signaling also upregulates AMPK activity and autophagy. Here, we investigated TAK1-dependent regulation of autophagy, lipid metabolism, and tumorigenesis in the liver. Fasted mice with hepatocyte-specific deletion of Tak1 exhibited severe hepatosteatosis with increased mTORC1 activity and suppression of autophagy compared with their WT counterparts. TAK1-deficient hepatocytes exhibited suppressed AMPK activity and autophagy in response to starvation or metformin treatment; however, ectopic activation of AMPK restored autophagy in these cells. Peroxisome proliferator–activated receptor α (PPARα) target genes and β-oxidation, which regulate hepatic lipid degradation, were also suppressed in hepatocytes lacking TAK1. Due to suppression of autophagy and β-oxidation, a high-fat diet challenge aggravated steatohepatitis in mice with hepatocyte-specific deletion of Tak1. Notably, inhibition of mTORC1 restored autophagy and PPARα target gene expression in TAK1-deficient livers, indicating that TAK1 acts upstream of mTORC1. mTORC1 inhibition also suppressed spontaneous liver fibrosis and hepatocarcinogenesis in animals with hepatocyte-specific deletion of Tak1. These data indicate that TAK1 regulates hepatic lipid metabolism and tumorigenesis via the AMPK/mTORC1 axis, affecting both autophagy and PPARα activity. PMID:24983318

  1. Dexamethasone-induced autophagy mediates muscle atrophy through mitochondrial clearance

    PubMed Central

    Troncoso, Rodrigo; Paredes, Felipe; Parra, Valentina; Gatica, Damián; Vásquez-Trincado, César; Quiroga, Clara; Bravo-Sagua, Roberto; López-Crisosto, Camila; Rodriguez, Andrea E; Oyarzún, Alejandra P; Kroemer, Guido; Lavandero, Sergio

    2014-01-01

    Glucocorticoids, such as dexamethasone, enhance protein breakdown via ubiquitin–proteasome system. However, the role of autophagy in organelle and protein turnover in the glucocorticoid-dependent atrophy program remains unknown. Here, we show that dexamethasone stimulates an early activation of autophagy in L6 myotubes depending on protein kinase, AMPK, and glucocorticoid receptor activity. Dexamethasone increases expression of several autophagy genes, including ATG5, LC3, BECN1, and SQSTM1 and triggers AMPK-dependent mitochondrial fragmentation associated with increased DNM1L protein levels. This process is required for mitophagy induced by dexamethasone. Inhibition of mitochondrial fragmentation by Mdivi-1 results in disrupted dexamethasone-induced autophagy/mitophagy. Furthermore, Mdivi-1 increases the expression of genes associated with the atrophy program, suggesting that mitophagy may serve as part of the quality control process in dexamethasone-treated L6 myotubes. Collectively, these data suggest a novel role for dexamethasone-induced autophagy/mitophagy in the regulation of the muscle atrophy program. PMID:24897381

  2. The Incredible ULKs: Autophagy and Beyond.

    PubMed

    Zhao, Yan G; Zhang, Hong

    2016-05-19

    Atg1 integrates nutrient status and autophagy. In this issue, Joo et al. (2016) reveal that the mammalian Atg1 homologs ULK1/2 are dispensable for neuronal basal autophagy. ULK1/2 phosphorylate SEC16A and regulate ER export, expanding the autophagy-independent functions of autophagy proteins. PMID:27203174

  3. Oxidative Stress Contributes to Autophagy Induction in Response to Endoplasmic Reticulum Stress in Chlamydomonas reinhardtii1[W

    PubMed Central

    Pérez-Martín, Marta; Pérez-Pérez, María Esther; Lemaire, Stéphane D.; Crespo, José L.

    2014-01-01

    The accumulation of unfolded/misfolded proteins in the endoplasmic reticulum (ER) results in the activation of stress responses, such as the unfolded protein response or the catabolic process of autophagy to ultimately recover cellular homeostasis. ER stress also promotes the production of reactive oxygen species, which play an important role in autophagy regulation. However, it remains unknown whether reactive oxygen species are involved in ER stress-induced autophagy. In this study, we provide evidence connecting redox imbalance caused by ER stress and autophagy activation in the model unicellular green alga Chlamydomonas reinhardtii. Treatment of C. reinhardtii cells with the ER stressors tunicamycin or dithiothreitol resulted in up-regulation of the expression of genes encoding ER resident endoplasmic reticulum oxidoreductin1 oxidoreductase and protein disulfide isomerases. ER stress also triggered autophagy in C. reinhardtii based on the protein abundance, lipidation, cellular distribution, and mRNA levels of the autophagy marker ATG8. Moreover, increases in the oxidation of the glutathione pool and the expression of oxidative stress-related genes were detected in tunicamycin-treated cells. Our results revealed that the antioxidant glutathione partially suppressed ER stress-induced autophagy and decreased the toxicity of tunicamycin, suggesting that oxidative stress participates in the control of autophagy in response to ER stress in C. reinhardtii In close agreement, we also found that autophagy activation by tunicamycin was more pronounced in the C. reinhardtii sor1 mutant, which shows increased expression of oxidative stress-related genes. PMID:25143584

  4. Novel enabling technologies of gene isolation and plant transformation for improved crop protection

    SciTech Connect

    Torok, Tamas

    2013-02-04

    Meeting the needs of agricultural producers requires the continued development of improved transgenic crop protection products. The completed project focused on developing novel enabling technologies of gene discovery and plant transformation to facilitate the generation of such products.

  5. Structure biology of selective autophagy receptors

    PubMed Central

    Kim, Byeong-Won; Kwon, Do Hoon; Song, Hyun Kyu

    2016-01-01

    Autophagy is a process tightly regulated by various autophagy-related proteins. It is generally classified into non-selective and selective autophagy. Whereas non-selective autophagy is triggered when the cell is under starvation, selective autophagy is involved in eliminating dysfunctional organelles, misfolded and/or ubiquitylated proteins, and intracellular pathogens. These components are recognized by autophagy receptors and delivered to phagophores. Several selective autophagy receptors have been identified and characterized. They usually have some common domains, such as motif, a specific cargo interacting (ubiquitin-dependent or ubiquitin-independent) domain. Recently, structural data of these autophagy receptors has been described, which provides an insight of their function in the selective autophagic process. In this review, we summarize the most up-to-date findings about the structure-function of autophagy receptors that regulates selective autophagy. [BMB Reports 2016; 49(2): 73-80] PMID:26698872

  6. Autophagy in Alcohol-Induced Multiorgan Injury: Mechanisms and Potential Therapeutic Targets

    PubMed Central

    Wang, Shaogui; Ni, Hong-Min; Huang, Heqing

    2014-01-01

    Autophagy is a genetically programmed, evolutionarily conserved intracellular degradation pathway involved in the trafficking of long-lived proteins and cellular organelles to the lysosome for degradation to maintain cellular homeostasis. Alcohol consumption leads to injury in various tissues and organs including liver, pancreas, heart, brain, and muscle. Emerging evidence suggests that autophagy is involved in alcohol-induced tissue injury. Autophagy serves as a cellular protective mechanism against alcohol-induced tissue injury in most tissues but could be detrimental in heart and muscle. This review summarizes current knowledge about the role of autophagy in alcohol-induced injury in different tissues/organs and its potential molecular mechanisms as well as possible therapeutic targets based on modulation of autophagy. PMID:25140315

  7. Endoplasmic reticulum stress-induced autophagy determines the susceptibility of melanoma cells to dabrafenib

    PubMed Central

    Ji, Chao; Zhang, Ziping; Chen, Lihong; Zhou, Kunli; Li, Dongjun; Wang, Ping; Huang, Shuying; Gong, Ting; Cheng, Bo

    2016-01-01

    Melanoma is one of the deadliest skin cancers and accounts for most skin-related deaths due to strong resistance to chemotherapy drugs. In the present study, we investigated the mechanisms of dabrafenib-induced drug resistance in human melanoma cell lines A375 and MEL624. Our studies support that both endoplasmic reticulum (ER) stress and autophagy were induced in the melanoma cells after the treatment with dabrafenib. In addition, ER stress-induced autophagy protects melanoma cells from the toxicity of dabrafenib. Moreover, inhibition of both ER stress and autophagy promote the sensitivity of melanoma cells to dabrafenib. Taken together, the data suggest that ER stress-induced autophagy determines the sensitivity of melanoma cells to dabrafenib. These results provide us with promising evidence that the inhibition of autophagy and ER stress could serve a therapeutic effect for the conventional dabrafenib chemotherapy. PMID:27536070

  8. Neutrophil gelatinase-associated lipocalin worsens ischemia/reperfusion damage of kidney cells by autophagy.

    PubMed

    Zhang, Wenjing; Yang, Shuo; Cui, Liyan; Zhang, Jie

    2016-08-01

    This study aimed to explore the influence of neutrophil gelatinase-associated lipocalin on autophagy and its role in ischemia/reperfusion injury in human kidney-2 (HK-2) cells during acute kidney injury (AKI). HK-2 cells were given hypoxia/reoxygenation treatment for different times to simulate ischemia/reperfusion injury. Autophagy was evaluated by western blot and immunofluorescence of GFP-LC3. Cell viability was tested to reflect the degree of cell damage. The autophagy inhibitor 3-MA was used to inhibit autophagy and determine the role of autophagy in ischemia/reperfusion injury. HK-2 cells were hypoxia for 1 h, followed by reoxygenation treatment for 24 h. These cells were then exposed to human recombinant protein neutrophil gelatinase-associated lipocalin (NGAL) (50, 100, 200, 400, or 1000 ng/mL) with or without 3-MA. Our results showed that autophagy was induced by hypoxia treatment and was further enhanced by reoxygenation after hypoxia treatment. Cell viability was decreased with the inhibition of autophagy in the process. Autophagic flux was further induced with NGAL (>200 ng/mL), while cell viability declined in this condition. Cell viability was recovered when autophagy was inhibited. These results indicate that autophagy plays, in part, a protective role in renal ischemia/reperfusion injury. Furthermore, the data suggest that NGAL strengthens the level of autophagy in this process. Overall, a large quantity of NGAL produced by renal proximal tubular epithelial cells may induce excessive autophagy and increase renal ischemia/reperfusion injury in acute kidney injury. PMID:27380103

  9. High Glucose Accelerates Autophagy in Adult Rat Intervertebral Disc Cells

    PubMed Central

    Kong, Chae-Gwan; Kim, Man Soo; Park, Eun-Young

    2014-01-01

    Study Design In vitro cell culture. Purpose The purpose of this study was to investigate the effect of high glucose on autophagy in adult rat intervertebral disc cells. Overview of Literature Diabetes mellitus is considered to be an important etiologic factor for intervertebral disc degeneration, resulting in degenerative disc diseases. A glucose-mediated increase of autophagy is a major causative factor for the development of diseases associated with diabetes mellitus. However, no information is available for the effect of high glucose on autophagy in adult intervertebral disc cells. Methods Nucleus pulposus and annulus fibrosus cells were isolated from 24-week-old adult rats, cultured and placed in either 10% fetal bovine serum (normal control) or 10% fetal bovine serum plus two different high glucose concentrations (0.1 M and 0.2 M) (experimental conditions) for one and three days, respectively. The expressions of autophagy markers, such as beclin-1, light chain 3-I (LC3-I) and LC3-II, autophagy-related gene (Atg) 3, 5, 7 and 12, were identified and quantified. Results Two high glucoses significantly increased the expressions of beclin-1, LC3-II, Atg3, 5, 7, and 12 in adult rat nucleus pulposus and annulus fibrosus cells in a dose- and time-dependent manner. The ratio of LC3-II/LC3-I expression was also increased in a dose-respectively time-dependent manner. Conclusions The results suggest that autophagy of adult nucleus pulposus and annulus fibrosus cells might be a potential mechanism for the intervertebral disc degeneration in adult patients with diabetes mellitus. Thus, the prevention of autophagy in adult intervertebral disc cells might be considered as a novel therapeutic target to prevent or to delay the intervertebral disc degeneration in adult patients with diabetes mellitus. PMID:25346805

  10. Crocin-Elicited Autophagy Rescues Myocardial Ischemia/Reperfusion Injury via Paradoxical Mechanisms.

    PubMed

    Zeng, Chao; Li, Hu; Fan, Zhiwen; Zhong, Lei; Guo, Zhen; Guo, Yaping; Xi, Yusheng

    2016-01-01

    Crocin, the main effective component of saffron, exerts protective effects against ischemia/reperfusion injury during strokes. However, the effects of crocin in myocardial ischemia/reperfusion injury, and the mechanisms involved, remain unknown. Pretreated with crocin for 7 days, C57BL/6N mice were subjected to 30 min of myocardial ischemia followed by 12[Formula: see text]h of reperfusion (for cardiac function and infarct size, cell apoptosis and necrosis). Neonatal mouse cardiomyocytes were subjected to 2 h of hypoxia followed by 4 h of reoxygenation. NMCM's survival was assessed during hypoxia and reoxygenation in the presence or absence of the autophagy inhibitor 3-methyladenine or the inducer rapamycin. Western blotting was used to evaluate AMPK, Akt, and autophagy-related proteins. Autophagosome was observed using electron microscopy. In the in vivo experiment, crocin pretreatment significantly attenuated infarct size, myocardial apoptosis and necrosis, and improved left ventricular function following ischemia/reperfusion. In vitro data revealed that autophagy was induced during hypoxia, the levels of which were intensely elevated during reoxygenation. Crocin significantly promoted autophagy during ischemia, accompanied with the activation of AMPK. In contrast, crocin overtly inhibited autophagy during reperfusion, accompanied with Akt activation. Induction and inhibition of autophagy mitigated crocin induced protection against NMCMs injury during hypoxia and reoxygenation, respectively. Our data suggest that crocin demonstrated a myocardial protective effect via AMPK/mTOR and Akt/mTOR regulated autophagy against ischemia and reperfusion injury, respectively. PMID:27109157

  11. Autophagy in 5-Fluorouracil Therapy in Gastrointestinal Cancer: Trends and Challenges

    PubMed Central

    Tang, Jia-Cheng; Feng, Yi-Li; Liang, Xiao; Cai, Xiu-Jun

    2016-01-01

    Objective: 5-Fluorouracil (5-FU)-based combination therapies are standard treatments for gastrointestinal cancer, where the modulation of autophagy is becoming increasingly important in offering effective treatment for patients in clinical practice. This review focuses on the role of autophagy in 5-FU-induced tumor suppression and cancer therapy in the digestive system. Data Sources: All articles published in English from 1996 to date those assess the synergistic effect of autophagy and 5-FU in gastrointestinal cancer therapy were identified through a systematic online search by use of PubMed. The search terms were “autophagy” and “5-FU” and (“colorectal cancer” or “hepatocellular carcinoma” or “pancreatic adenocarcinoma” or “esophageal cancer” or “gallbladder carcinoma” or “gastric cancer”). Study Selection: Critical reviews on relevant aspects and original articles reporting in vitro and/or in vivo results regarding the efficiency of autophagy and 5-FU in gastrointestinal cancer therapy were reviewed, analyzed, and summarized. The exclusion criteria for the articles were as follows: (1) new materials (e.g., nanomaterial)-induced autophagy; (2) clinical and experimental studies on diagnostic and/or prognostic biomarkers in digestive system cancers; and (3) immunogenic cell death for anticancer chemotherapy. Results: Most cell and animal experiments showed inhibition of autophagy by either pharmacological approaches or via genetic silencing of autophagy regulatory gene, resulting in a promotion of 5-FU-induced cancer cells death. Meanwhile, autophagy also plays a pro-death role and may mediate cell death in certain cancer cells where apoptosis is defective or difficult to induce. The dual role of autophagy complicates the use of autophagy inhibitor or inducer in cancer chemotherapy and generates inconsistency to an extent in clinic trials. Conclusion: Autophagy might be a therapeutic target that sensitizes the 5-FU treatment in

  12. Targeted deletion of Atg5 reveals differential roles of autophagy in keratin K5-expressing epithelia

    SciTech Connect

    Sukseree, Supawadee; Rossiter, Heidemarie; Mildner, Michael; Pammer, Johannes; Buchberger, Maria; Gruber, Florian; Watanapokasin, Ramida; Tschachler, Erwin; Eckhart, Leopold

    2013-01-11

    Highlights: Black-Right-Pointing-Pointer We generated mice lacking Atg5 and autophagy in keratin K5-positive epithelia. Black-Right-Pointing-Pointer Suppression of autophagy in thymic epithelium was not associated with signs of autoimmunity. Black-Right-Pointing-Pointer Autophagy was required for normal terminal differentiation of preputial gland cells. Black-Right-Pointing-Pointer Autophagy-deficient cells of the preputial glands degraded nuclear DNA prematurely. -- Abstract: Autophagy contributes to the homeostasis of many tissues, yet its role in epithelia is incompletely understood. A recent report proposed that Atg5-dependent autophagy in thymic epithelial cells is essential for their function in the negative selection of self-reactive T-cells and, thus, for the suppression of tissue inflammation. Here we crossed mice carrying floxed alleles of the Atg5 gene with mice expressing the Cre recombinase under the control of the keratin K5 promoter to suppress autophagy in all K5-positive epithelia. The efficiency of autophagy abrogation was confirmed by immunoanalyses of LC3, which was converted to the autophagy-associated LC3-II form in normal but not Atg5-deficient cells, and of p62, which accumulated in Atg5-deficient cells. Mice carrying the epithelium-specific deletion of Atg5 showed normal weight gain, absence of tissue inflammation, and a normal morphology of the thymic epithelium. By contrast, autophagy-deficient epithelial cells of the preputial gland showed aberrant eosinophilic staining in histology and premature degradation of nuclear DNA during terminal differentiation. Taken together, the results of this study suggest that autophagy is dispensable for the suppression of autoimmunity by thymic epithelial cells but essential for normal differentiation of the preputial gland in mice.

  13. The role of autophagy in pancreatic beta-cell and diabetes.

    PubMed

    Fujitani, Yoshio; Kawamori, Ryuzo; Watada, Hirotaka

    2009-02-01

    Pancreatic beta-cells play a key role in glucose homeostasis in mammals. Although large-scale protein synthesis and degradation occur in pancreatic beta-cells, the mechanism underlying dynamic protein turnover in beta-cells remains largely unknown. We found low-level constitutive autophagy in beta-cells of C57BL/6 mice fed a standard diet; however, autophagy was markedly upregulated in mice fed a high-fat diet. beta-cells of diabetic db/db mice contained large numbers of autophagosomes, compared with nondiabetic db/misty controls. The functional importance of autophagy was analyzed using beta-cell-specific Atg7 knockout mice. Autophagy-deficient mice showed degeneration of beta-cells and impaired glucose tolerance with reduced insulin secretion. While a high-fat diet stimulated beta-cell autophagy in control mice, it induced a profound deterioration of glucose intolerance in beta-cell autophagy-deficient mutants, partly because of the lack of a compensatory increase in beta-cell mass. These results suggest that the degradation of unnecessary cellular components by autophagy is essential for maintenance of the architecture and function of beta-cells. Autophagy also serves as a crucial element of stress responses to protect beta-cells under insulin-resistant states. Impairment of autophagic machinery could thus predispose individuals to type 2 diabetes. PMID:19158492

  14. Function and Mechanisms of Autophagy in Brain and Spinal Cord Trauma

    PubMed Central

    Wu, Junfang; Faden, Alan I.; Sarkar, Chinmoy

    2015-01-01

    Abstract Significance: Traumatic brain injury (TBI) and spinal cord injury (SCI) are major causes of death and long-term disability worldwide. Despite important pathophysiological differences between these disorders, in many respects, mechanisms of injury are similar. During both TBI and SCI, some cells are directly mechanically injured, but more die as a result of injury-induced biochemical changes (secondary injury). Autophagy, a lysosome-dependent cellular degradation pathway with neuroprotective properties, has been implicated both clinically and experimentally in the delayed response to TBI and SCI. However, until recently, its mechanisms and function remained unknown, reflecting in part the difficulty of isolating autophagic processes from ongoing cell death and other cellular events. Recent Advances: Emerging data suggest that depending on the location and severity of traumatic injury, autophagy flux—defined as the progress of cargo through the autophagy system and leading to its degradation—may be either increased or decreased after central nervous system trauma. Critical Issues: While increased autophagy flux may be protective after mild injury, after more severe trauma inhibition of autophagy flux may contribute to neuronal cell death, indicating disruption of autophagy as a part of the secondary injury mechanism. Future Directions: Augmentation and/or restoration of autophagy flux may provide a potential therapeutic target for treatment of TBI and SCI. Development of those treatments will require thorough characterization of changes in autophagy flux, its mechanisms and function over time after injury. Antioxid. Redox Signal. 23, 565–577. PMID:25808205

  15. Differential roles of unsaturated and saturated fatty acids on autophagy and apoptosis in hepatocytes.

    PubMed

    Mei, Shuang; Ni, Hong-Min; Manley, Sharon; Bockus, Abigail; Kassel, Karen M; Luyendyk, James P; Copple, Bryan L; Ding, Wen-Xing

    2011-11-01

    Fatty acid-induced lipotoxicity plays a critical role in the pathogenesis of nonalcoholic liver disease. Saturated fatty acids and unsaturated fatty acids have differential effects on cell death and steatosis, but the mechanisms responsible for these differences are not known. Using cultured HepG2 cells and primary mouse hepatocytes, we found that unsaturated and saturated fatty acids differentially regulate autophagy and apoptosis. The unsaturated fatty acid, oleic acid, promoted the formation of triglyceride-enriched lipid droplets and induced autophagy but had a minimal effect on apoptosis. In contrast, the saturated fatty acid, palmitic acid, was poorly converted into triglyceride-enriched lipid droplets, suppressed autophagy, and significantly induced apoptosis. Subsequent studies revealed that palmitic acid-induced apoptosis suppressed autophagy by inducing caspase-dependent Beclin 1 cleavage, indicating cross-talk between apoptosis and autophagy. Moreover, our data suggest that the formation of triglyceride-enriched lipid droplets and induction of autophagy are protective mechanisms against fatty acid-induced lipotoxicity. In line with our in vitro findings, we found that high-fat diet-induced hepatic steatosis was associated with autophagy in the mouse liver. Potential modulation of autophagy may be a novel approach that has therapeutic benefits for obesity-induced steatosis and liver injury. PMID:21856859

  16. Autophagy contributes to regulation of the hypoxia response during submergence in Arabidopsis thaliana

    PubMed Central

    Chen, Liang; Liao, Bin; Qi, Hua; Xie, Li-Juan; Huang, Li; Tan, Wei-Juan; Zhai, Ning; Yuan, Li-Bing; Zhou, Ying; Yu, Lu-Jun; Chen, Qin-Fang; Shu, Wensheng; Xiao, Shi

    2015-01-01

    Autophagy involves massive degradation of intracellular components and functions as a conserved system that helps cells to adapt to adverse conditions. In mammals, hypoxia rapidly stimulates autophagy as a cell survival response. Here, we examine the function of autophagy in the regulation of the plant response to submergence, an abiotic stress that leads to hypoxia and anaerobic respiration in plant cells. In Arabidopsis thaliana, submergence induces the transcription of autophagy-related (ATG) genes and the formation of autophagosomes. Consistent with this, the autophagy-defective (atg) mutants are hypersensitive to submergence stress and treatment with ethanol, the end product of anaerobic respiration. Upon submergence, the atg mutants have increased levels of transcripts of anaerobic respiration genes (alcohol dehydrogenase 1, ADH1 and pyruvate decarboxylase 1, PDC1), but reduced levels of transcripts of other hypoxia- and ethylene-responsive genes. Both submergence and ethanol treatments induce the accumulation of reactive oxygen species (ROS) in the rosettes of atg mutants more than in the wild type. Moreover, the production of ROS by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidases is necessary for plant tolerance to submergence and ethanol, submergence-induced expression of ADH1 and PDC1, and activation of autophagy. The submergence- and ethanol-sensitive phenotypes in the atg mutants depend on a complete salicylic acid (SA) signaling pathway. Together, our findings demonstrate that submergence-induced autophagy functions in the hypoxia response in Arabidopsis by modulating SA-mediated cellular homeostasis. PMID:26566261

  17. The cardioprotective compound cloxyquin uncouples mitochondria and induces autophagy.

    PubMed

    Zhang, Jimmy; Nadtochiy, Sergiy M; Urciuoli, William R; Brookes, Paul S

    2016-01-01

    Mitochondrial quality control mechanisms have been implicated in protection against cardiac ischemia-reperfusion (IR) injury. Previously, cloxyquin (5-chloroquinolin-8-ol) was identified via phenotypic screening as a cardioprotective compound. Herein, cloxyquin was identified as a mitochondrial uncoupler in both isolated heart mitochondria and adult cardiomyocytes. Additionally, cardiomyocytes isolated from transgenic mice expressing green fluorescent protein-tagged microtubule-associated protein light chain 3 showed increased autophagosome formation with cloxyquin treatment. The autophagy inhibitor chloroquine abolished cloxyquin-induced cardioprotection in both cellular and perfused heart (Langendorff) models of IR injury. Finally, in an in vivo murine left anterior descending coronary artery occlusion model of IR injury, cloxyquin significantly reduced infarct size from 31.4 ± 3.4% to 16.1 ± 2.2%. In conclusion, the cardioprotective compound cloxyquin simultaneously uncoupled mitochondria and induced autophagy. Importantly, autophagy appears to be required for cloxyquin-induced cardioprotection. PMID:26519034

  18. Methylprednisolone exerts neuroprotective effects by regulating autophagy and apoptosis

    PubMed Central

    Gao, Wei; Chen, Shu-rui; Wu, Meng-yao; Gao, Kai; Li, Yuan-long; Wang, Hong-yu; Li, Chen-yuan; Li, Hong

    2016-01-01

    Methylprednisolone markedly reduces autophagy and apoptosis after secondary spinal cord injury. Here, we investigated whether pretreatment of cells with methylprednisolone would protect neuron-like cells from subsequent oxidative damage via suppression of autophagy and apoptosis. Cultured N2a cells were pretreated with 10 µM methylprednisolone for 30 minutes, then exposed to 100 µM H2O2 for 24 hours. Inverted phase contrast microscope images, MTT assay, flow cytometry and western blot results showed that, compared to cells exposed to 100 µM H2O2 alone, cells pretreated with methylprednisolone had a significantly lower percentage of apoptotic cells, maintained a healthy morphology, and showed downregulation of autophagic protein light chain 3B and Beclin-1 protein expression. These findings indicate that methylprednisolone exerted neuroprotective effects against oxidative damage by suppressing autophagy and apoptosis. PMID:27335569

  19. Methylprednisolone exerts neuroprotective effects by regulating autophagy and apoptosis.

    PubMed

    Gao, Wei; Chen, Shu-Rui; Wu, Meng-Yao; Gao, Kai; Li, Yuan-Long; Wang, Hong-Yu; Li, Chen-Yuan; Li, Hong

    2016-05-01

    Methylprednisolone markedly reduces autophagy and apoptosis after secondary spinal cord injury. Here, we investigated whether pretreatment of cells with methylprednisolone would protect neuron-like cells from subsequent oxidative damage via suppression of autophagy and apoptosis. Cultured N2a cells were pretreated with 10 µM methylprednisolone for 30 minutes, then exposed to 100 µM H2O2 for 24 hours. Inverted phase contrast microscope images, MTT assay, flow cytometry and western blot results showed that, compared to cells exposed to 100 µM H2O2 alone, cells pretreated with methylprednisolone had a significantly lower percentage of apoptotic cells, maintained a healthy morphology, and showed downregulation of autophagic protein light chain 3B and Beclin-1 protein expression. These findings indicate that methylprednisolone exerted neuroprotective effects against oxidative damage by suppressing autophagy and apoptosis. PMID:27335569

  20. Ammonia Induces Autophagy through Dopamine Receptor D3 and MTOR

    PubMed Central

    Li, Zhiyuan; Ji, Xinmiao; Wang, Wenchao; Liu, Juanjuan; Liang, Xiaofei; Wu, Hong; Liu, Jing; Eggert, Ulrike S.; Liu, Qingsong

    2016-01-01

    Hyperammonemia is frequently seen in tumor microenvironments as well as in liver diseases where it can lead to severe brain damage or death. Ammonia induces autophagy, a mechanism that tumor cells may use to protect themselves from external stresses. However, how cells sense ammonia has been unclear. Here we show that culture medium alone containing Glutamine can generate milimolar of ammonia at 37 degrees in the absence of cells. In addition, we reveal that ammonia acts through the G protein-coupled receptor DRD3 (Dopamine receptor D3) to induce autophagy. At the same time, ammonia induces DRD3 degradation, which involves PIK3C3/VPS34-dependent pathways. Ammonia inhibits MTOR (mechanistic target of Rapamycin) activity and localization in cells, which is mediated by DRD3. Therefore, ammonia has dual roles in autophagy: one to induce autophagy through DRD3 and MTOR, the other to increase autophagosomal pH to inhibit autophagic flux. Our study not only adds a new sensing and output pathway for DRD3 that bridges ammonia sensing and autophagy induction, but also provides potential mechanisms for the clinical consequences of hyperammonemia in brain damage, neurodegenerative diseases and tumors. PMID:27077655

  1. Boosting autophagy in the diabetic heart: a translational perspective.

    PubMed

    Sciarretta, Sebastiano; Boppana, V Subbarao; Umapathi, Mahaa; Frati, Giacomo; Sadoshima, Junichi

    2015-10-01

    Diabetes, obesity, and dyslipidemia are main risk factors that promote the development of cardiovascular diseases. These metabolic abnormalities are frequently found to be associated together in a highly morbid clinical condition called metabolic syndrome. Metabolic derangements promote endothelial dysfunction, atherosclerotic plaque formation and rupture, cardiac remodeling and dysfunction. This evidence strongly encourages the elucidation of the mechanisms through which obesity, diabetes, and metabolic syndrome induce cellular abnormalities and dysfunction in order to discover new therapeutic targets and strategies for their prevention and treatment. Numerous studies employing both dietary and genetic animal models of obesity and diabetes have demonstrated that autophagy, an intracellular system for protein degradation, is impaired in the heart under these conditions. This suggests that autophagy reactivation may represent a future potential therapeutic intervention to reduce cardiac maladaptive alterations in patients with metabolic derangements. In fact, autophagy is a critical mechanism to preserve cellular homeostasis and survival. In addition, the physiological activation of autophagy protects the heart during stress, such as acute ischemia, starvation, chronic myocardial infarction, pressure overload, and proteotoxic stress. All these aspects will be discussed in our review article together with the potential ways to reactivate autophagy in the context of obesity, metabolic syndrome, and diabetes. PMID:26543826

  2. Boosting autophagy in the diabetic heart: a translational perspective

    PubMed Central

    Boppana, V. Subbarao; Umapathi, Mahaa; Frati, Giacomo

    2015-01-01

    Diabetes, obesity, and dyslipidemia are main risk factors that promote the development of cardiovascular diseases. These metabolic abnormalities are frequently found to be associated together in a highly morbid clinical condition called metabolic syndrome. Metabolic derangements promote endothelial dysfunction, atherosclerotic plaque formation and rupture, cardiac remodeling and dysfunction. This evidence strongly encourages the elucidation of the mechanisms through which obesity, diabetes, and metabolic syndrome induce cellular abnormalities and dysfunction in order to discover new therapeutic targets and strategies for their prevention and treatment. Numerous studies employing both dietary and genetic animal models of obesity and diabetes have demonstrated that autophagy, an intracellular system for protein degradation, is impaired in the heart under these conditions. This suggests that autophagy reactivation may represent a future potential therapeutic intervention to reduce cardiac maladaptive alterations in patients with metabolic derangements. In fact, autophagy is a critical mechanism to preserve cellular homeostasis and survival. In addition, the physiological activation of autophagy protects the heart during stress, such as acute ischemia, starvation, chronic myocardial infarction, pressure overload, and proteotoxic stress. All these aspects will be discussed in our review article together with the potential ways to reactivate autophagy in the context of obesity, metabolic syndrome, and diabetes. PMID:26543826

  3. Autophagy in immunity

    PubMed Central

    Zhou, Xu-Jie; Zang, Hong

    2012-01-01

    Autophagy is now emerging as a spotlight in trafficking events that activate innate and adaptive immunity. It facilitates innate pathogen detection and antigen presentation, as well as pathogen clearance and lymphocyte homeostasis. In this review, we first summarize new insights into its functions in immunity, which underlie its associations with autoimmunity. As some lines of evidence are emerging to support its role in autoimmune and autoinflammatory diseases, we further discuss whether and how it affects autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, diabetes mellitus and multiple sclerosis, as well as autoinflammatory diseases, such as Crohn disease and vitiligo. PMID:22878595

  4. [Protection of corneal endothelium from apoptosis by gene and cell therapy].

    PubMed

    Fuchsluger, T A

    2016-06-01

    Protection of corneal endothelium from apoptosis using gene and cell therapy is in a translational phase. This approach offers advantages for eye banking and after transplantation. Safe vehicles for gene or cell therapeutic transduction of corneal endothelium with nucleic acids are available. This strategy will be further developed in consultation with the Paul Ehrlich Institute and European regulatory authorities. PMID:27260626

  5. Quercetin blocks t-AUCB-induced autophagy by Hsp27 and Atg7 inhibition in glioblastoma cells in vitro.

    PubMed

    Li, Junyang; Tang, Chao; Li, Liwen; Li, Rujun; Fan, Youwu

    2016-08-01

    We previously demonstrated that the acquired resistance because of Hsp27 activation weakens the cytotoxic effect of t-AUCB on glioblastoma cells. Since autophagy is regarded as a survival mechanism for cells exposed to cytotoxic agents, the aim of this study is to investigate whether t-AUCB induces autophagy and whether Hsp27 and autophagy are interacted with each other. Our data demonstrated that t-AUCB induces autophagy in glioblastoma cells and regulates multiple autophagy related-gene expression. t-AUCB induces overexpression of Atg7, which is downstream of Hsp27 and participates in the resistance of glioblastoma cells to t-AUCB treatment. Hsp27 inhibitor quercetin suppresses Atg7 expression and strengthens t-AUCB-induced cell death by autophagy blockage. We concluded that combination of quercetin and t-AUCB might be a potential strategy for glioblastoma treatment. PMID:27174198

  6. Trehalose prevents neural tube defects by correcting maternal diabetes-suppressed autophagy and neurogenesis

    PubMed Central

    Xu, Cheng; Li, Xuezheng; Wang, Fang; Weng, Hongbo

    2013-01-01

    Preexisting maternal diabetes increases the risk of neural tube defects (NTDs). The mechanism underlying maternal diabetes-induced NTDs is not totally defined, and its prevention remains a challenge. Autophagy, an intracellular process to degrade dysfunction protein and damaged cellular organelles, regulates cell proliferation, differentiation, and apoptosis. Because autophagy impairment causes NTDs reminiscent of those observed in diabetic pregnancies, we hypothesize that maternal diabetes-induced autophagy impairment causes NTD formation by disrupting cellular homeostasis, leading to endoplasmic reticulum (ER) stress and apoptosis, and that restoration of autophagy by trehalose, a natural disaccharide, prevents diabetes-induced NTDs. Embryos from nondiabetic and type 1 diabetic mice fed with or without 2 or 5% trehalose water were used to assess markers of autophagy, ER stress, and neurogenesis, numbers of autophagosomes, gene expression that regulates autophagy, NTD rates, indices of mitochondrial dysfunction, and neuroepithelial cell apoptosis. Maternal diabetes suppressed autophagy by significantly reducing LC3-II expression, autophagosome numbers, and GFP-LC3 punctate foci in neuroepithelial cells and by altering autophagy-related gene expression. Maternal diabetes delayed neurogenesis by blocking Sox1 neural progenitor differentiation. Trehalose treatment reversed autophagy impairment and prevented NTDs in diabetic pregnancies. Trehalose resolved homeostatic imbalance by correcting mitochondrial defects, dysfunctional proteins, ER stress, apoptosis, and delayed neurogenesis in the neural tubes exposed to hyperglycemia. Our study demonstrates for the first time that maternal diabetes suppresses autophagy in neuroepithelial cells of the developing neural tube, leading to NTD formation, and provides evidence for the potential efficacy of trehalose as an intervention against hyperglycemia-induced NTDs. PMID:23880312

  7. Rejuvenation of MPTP-induced human neural precursor cell senescence by activating autophagy

    SciTech Connect

    Zhu, Liang; Dong, Chuanming; Sun, Chenxi; Ma, Rongjie; Yang, Danjing; Zhu, Hongwen; Xu, Jun

    2015-08-21

    Aging of neural stem cell, which can affect brain homeostasis, may be caused by many cellular mechanisms. Autophagy dysfunction was found in aged and neurodegenerative brains. However, little is known about the relationship between autophagy and human neural stem cell (hNSC) aging. The present study used 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) to treat neural precursor cells (NPCs) derived from human embryonic stem cell (hESC) line H9 and investigate related molecular mechanisms involved in this process. MPTP-treated NPCs were found to undergo premature senescence [determined by increased senescence-associated-β-galactosidase (SA-β-gal) activity, elevated intracellular reactive oxygen species level, and decreased proliferation] and were associated with impaired autophagy. Additionally, the cellular senescence phenotypes were manifested at the molecular level by a significant increase in p21 and p53 expression, a decrease in SOD2 expression, and a decrease in expression of some key autophagy-related genes such as Atg5, Atg7, Atg12, and Beclin 1. Furthermore, we found that the senescence-like phenotype of MPTP-treated hNPCs was rejuvenated through treatment with a well-known autophagy enhancer rapamycin, which was blocked by suppression of essential autophagy gene Beclin 1. Taken together, these findings reveal the critical role of autophagy in the process of hNSC aging, and this process can be reversed by activating autophagy. - Highlights: • We successfully establish hESC-derived neural precursor cells. • MPTP treatment induced senescence-like state in hESC-derived NPCs. • MPTP treatment induced impaired autophagy of hESC-derived NPCs. • MPTP-induced hESC-derived NPC senescence was rejuvenated by activating autophagy.

  8. Participation of autophagy in the cytotoxicity against breast cancer cells by cisplatin.

    PubMed

    Shen, Meng; Duan, Wei-Ming; Wu, Meng-Yao; Wang, Wen-Jie; Liu, Lu; Xu, Meng-Dan; Zhu, Jie; Li, Dao-Ming; Gui, Qi; Lian, Lian; Gong, Fei-Ran; Chen, Kai; Li, Wei; Tao, Min

    2015-07-01

    Breast cancer is one of the most common cancers affecting women worldwide. Conventional chemotherapy is still one of the major approaches to the treatment of breast cancer. Autophagy, also termed as type II programmed cell death (PCD), exhibits either a protumorigenic or antitumorigenic function. In the present study, we investigated whether autophagy could be involved in the effect of chemotherapy against breast cancer. Epirubicin, docetaxel, methotrexate, cyclophosphamide, fluorouracil (5-FU) and cisplatin were applied in the present investigation. All of these chemotherapeutics presented cytotoxicity against breast cancer cells. DsRed-LC3 reporter assay revealed that only docetaxel and cisplatin induced autophagy. Autophagy inhibitor 3-methyladenine (3-MA) strengthened the cytotoxicity of docetaxel, yet impaired the cytotoxicity of cisplatin, suggesting that docetaxel stimulates protumorigenic autophagy, while cisplatin-induced autophagy could be antitumorigenic. Real-time PCR revealed that cisplatin upregulated multiple autophagy-related genes, including AMBRA1, ATG3, ATG4C, ATG4D, ATG5, ATG7, ATG13, ATG14, ATG16L2, Beclin1, DRAM1, GABARAP, GABARAPL1, GABARAPL2, HDAC6, IRGM, MAP1LC3B and ULK1, indicating that cisplatin induced autophagy through a multiple mechanism involved manner. PMID:26005215

  9. Hydrophobic statins induce autophagy and cell death in human rhabdomyosarcoma cells by depleting geranylgeranyl diphosphate.

    PubMed

    Araki, Makoto; Maeda, Masatomo; Motojima, Kiyoto

    2012-01-15

    Statins are the most common type of medicine used to treat hypercholesterolemia; however, they are associated with a low incidence of myotoxicity such as myopathy and rhabdomyolysis. The mechanisms for the adverse effects remain to be fully elucidated for safer chronic use and drug development. The results of our earlier work suggested that hydrophobic statins induce autophagy in cultured human rhabdomyosarcoma A204 cells. In this study, we first confirmed the statin-induced autophagy by assessing other criteria, including induced expression of the autophagy-related genes, enhanced protein degradation of autophagy marker protein p62 and electron microscopic observation of induced formation of autophagosome. We next demonstrated that the extent of inhibition of HMG-CoA reductase in the cell is parallel with the ability of a statin to induce autophagy. Thus, the primary activity of statins causes autophagy in A204 cells. Considering the mechanism for the induction, we showed that statins induce autophagy by depleting cellular levels of geranylgeranyl diphosphate (GGPP) mostly through an unknown pathway that does not involve two major small G proteins, Rheb and Ras. Finally, we demonstrated that the ability of statins to induce autophagy parallels their toxicity to A204 cells and that both can be suppressed by GGPP. PMID:22094060

  10. Regulatory coordination between two major intracellular homeostatic systems: heat shock response and autophagy.

    PubMed

    Dokladny, Karol; Zuhl, Micah Nathaniel; Mandell, Michael; Bhattacharya, Dhruva; Schneider, Suzanne; Deretic, Vojo; Moseley, Pope Lloyd

    2013-05-24

    The eukaryotic cell depends on multitiered homeostatic systems ensuring maintenance of proteostasis, organellar integrity, function and turnover, and overall cellular viability. At the two opposite ends of the homeostatic system spectrum are heat shock response and autophagy. Here, we tested whether there are interactions between these homeostatic systems, one universally operational in all prokaryotic and eukaryotic cells, and the other one (autophagy) is limited to eukaryotes. We found that heat shock response regulates autophagy. The interaction between the two systems was demonstrated by testing the role of HSF-1, the central regulator of heat shock gene expression. Knockdown of HSF-1 increased the LC3 lipidation associated with formation of autophagosomal organelles, whereas depletion of HSF-1 potentiated both starvation- and rapamycin-induced autophagy. HSP70 expression but not expression of its ATPase mutant inhibited starvation or rapamycin-induced autophagy. We also show that exercise induces autophagy in humans. As predicted by our in vitro studies, glutamine supplementation as a conditioning stimulus prior to exercise significantly increased HSP70 protein expression and prevented the expected exercise induction of autophagy. Our data demonstrate for the first time that heat shock response, from the top of its regulatory cascade (HSF-1) down to the execution stages delivered by HSP70, controls autophagy thus connecting and coordinating the two extreme ends of the homeostatic systems in the eukaryotic cell. PMID:23576438

  11. Autophagy regulates Notch degradation and modulates stem cell development and neurogenesis

    PubMed Central

    Wu, Xiaoting; Fleming, Angeleen; Ricketts, Thomas; Pavel, Mariana; Virgin, Herbert; Menzies, Fiona M.; Rubinsztein, David C.

    2016-01-01

    Autophagy is a conserved, intracellular, lysosomal degradation pathway. While mechanistic aspects of this pathway are increasingly well defined, it remains unclear how autophagy modulation impacts normal physiology. It is, however, becoming clear that autophagy may play a key role in regulating developmental pathways. Here we describe for the first time how autophagy impacts stem cell differentiation by degrading Notch1. We define a novel route whereby this plasma membrane-resident receptor is degraded by autophagy, via uptake into ATG16L1-positive autophagosome-precursor vesicles. We extend our findings using a physiologically relevant mouse model with a hypomorphic mutation in Atg16L1, a crucial autophagy gene, which shows developmental retention of early-stage cells in various tissues where the differentiation of stem cells is retarded and thus reveal how modest changes in autophagy can impact stem cell fate. This may have relevance for diverse disease conditions, like Alzheimer's Disease or Crohn's Disease, associated with altered autophagy. PMID:26837467

  12. miR-183 regulates autophagy and apoptosis in colorectal cancer through targeting of UVRAG

    PubMed Central

    Su, Xiaomin; Li, Linqiang; Du, Zhimin; Hu, Meiyu; Dong, Yuechao; Bai, Xue; Liu, Tianyi; Yang, Baofeng; Shan, Hongli

    2016-01-01

    Ultraviolet radiation resistance-associated gene (UVRAG) is a well-known regulator of autophagy by promoting autophagosome formation and maturation. Multiple studies have implicated UVRAG in the pathogenesis of colorectal cancer. However, the mechanisms underlying the regulation of UVRAG are unclear. Here, we describe miR-183 as a new autophagy-inhibiting miRNA. Our results showed that induction of autophagy lead to down-regulation of miR-183 in colorectal cancer cells. And, over-expression of miR-183 resulted in the attenuation of rapamycin- or starvation-induced autophagy in cancer cells, whereas inhibition of endogenous miR-183 stimulated autophagy and apoptosis. Additionally, either autophagy inhibitor 3-MA or pan-caspase inhibitor Z-VAD-FMK respectively or both treatments reversed AMO-183-induced cell death. Further studies showed that UVRAG is a target of miR-183 and as a key regulator promotes autophagy and apoptosis. More importantly, over-expression of UVRAG rescued autophagic activity and induced apoptosis in presence of miR-183. Therefore, the present study investigated the promoting effect of miR-183 on colorectal cancer progression, which was considered to be mediated by autophagy and apoptosis through targeting of UVRAG. PMID:26717041

  13. Targeting ER stress-induced autophagy overcomes BRAF inhibitor resistance in melanoma.

    PubMed

    Ma, Xiao-Hong; Piao, Sheng-Fu; Dey, Souvik; McAfee, Quentin; Karakousis, Giorgos; Villanueva, Jessie; Hart, Lori S; Levi, Samuel; Hu, Janice; Zhang, Gao; Lazova, Rossitza; Klump, Vincent; Pawelek, John M; Xu, Xiaowei; Xu, Wei; Schuchter, Lynn M; Davies, Michael A; Herlyn, Meenhard; Winkler, Jeffrey; Koumenis, Constantinos; Amaravadi, Ravi K

    2014-03-01

    Melanomas that result from mutations in the gene encoding BRAF often become resistant to BRAF inhibition (BRAFi), with multiple mechanisms contributing to resistance. While therapy-induced autophagy promotes resistance to a number of therapies, especially those that target PI3K/mTOR signaling, its role as an adaptive resistance mechanism to BRAFi is not well characterized. Using tumor biopsies from BRAF(V600E) melanoma patients treated either with BRAFi or with combined BRAF and MEK inhibition, we found that BRAFi-resistant tumors had increased levels of autophagy compared with baseline. Patients with higher levels of therapy-induced autophagy had drastically lower response rates to BRAFi and a shorter duration of progression-free survival. In BRAF(V600E) melanoma cell lines, BRAFi or BRAF/MEK inhibition induced cytoprotective autophagy, and autophagy inhibition enhanced BRAFi-induced cell death. Shortly after BRAF inhibitor treatment in melanoma cell lines, mutant BRAF bound the ER stress gatekeeper GRP78, which rapidly expanded the ER. Disassociation of GRP78 from the PKR-like ER-kinase (PERK) promoted a PERK-dependent ER stress response that subsequently activated cytoprotective autophagy. Combined BRAF and autophagy inhibition promoted tumor regression in BRAFi-resistant xenografts. These data identify a molecular pathway for drug resistance connecting BRAFi, the ER stress response, and autophagy and provide a rationale for combination approaches targeting this resistance pathway. PMID:24569374

  14. Autophagy regulates Notch degradation and modulates stem cell development and neurogenesis.

    PubMed

    Wu, Xiaoting; Fleming, Angeleen; Ricketts, Thomas; Pavel, Mariana; Virgin, Herbert; Menzies, Fiona M; Rubinsztein, David C

    2016-01-01

    Autophagy is a conserved, intracellular, lysosomal degradation pathway. While mechanistic aspects of this pathway are increasingly well defined, it remains unclear how autophagy modulation impacts normal physiology. It is, however, becoming clear that autophagy may play a key role in regulating developmental pathways. Here we describe for the first time how autophagy impacts stem cell differentiation by degrading Notch1. We define a novel route whereby this plasma membrane-resident receptor is degraded by autophagy, via uptake into ATG16L1-positive autophagosome-precursor vesicles. We extend our findings using a physiologically relevant mouse model with a hypomorphic mutation in Atg16L1, a crucial autophagy gene, which shows developmental retention of early-stage cells in various tissues where the differentiation of stem cells is retarded and thus reveal how modest changes in autophagy can impact stem cell fate. This may have relevance for diverse disease conditions, like Alzheimer's Disease or Crohn's Disease, associated with altered autophagy. PMID:26837467

  15. You are what you eat: multifaceted functions of autophagy during C. elegans development.

    PubMed

    Yang, Peiguo; Zhang, Hong

    2014-01-01

    Autophagy involves the sequestration of a portion of the cytosolic contents in an enclosed double-membrane autophagosomal structure and its subsequent delivery to lysosomes for degradation. Autophagy activity functions in multiple biological processes during Caenorhabditis elegans development. The basal level of autophagy in embryos removes aggregate-prone proteins, paternal mitochondria and spermatid-specific membranous organelles (MOs). Autophagy also contributes to the efficient removal of embryonic apoptotic cell corpses by promoting phagosome maturation. During larval development, autophagy modulates miRNA-mediated gene silencing by selectively degrading AIN-1, a component of miRNA-induced silencing complex, and thus participates in the specification of multiple cell fates controlled by miRNAs. During development of the hermaphrodite germline, autophagy acts coordinately with the core apoptotic machinery to execute genotoxic stress-induced germline cell death and also cell death when caspase activity is partially compromised. Autophagy is also involved in the utilization of lipid droplets in the aging process in adult animals. Studies in C. elegans provide valuable insights into the physiological functions of autophagy in the development of multicellular organisms. PMID:24296782

  16. Autophagy Contributes to Leaf Starch Degradation[C][W

    PubMed Central

    Wang, Yan; Yu, Bingjie; Zhao, Jinping; Guo, Jiangbo; Li, Ying; Han, Shaojie; Huang, Lei; Du, Yumei; Hong, Yiguo; Tang, Dingzhong; Liu, Yule

    2013-01-01

    Transitory starch, a major photosynthetic product in the leaves of land plants, accumulates in chloroplasts during the day and is hydrolyzed to maltose and Glc at night to support respiration and metabolism. Previous studies in Arabidopsis thaliana indicated that the degradation of transitory starch only occurs in the chloroplasts. Here, we report that autophagy, a nonplastidial process, participates in leaf starch degradation. Excessive starch accumulation was observed in Nicotiana benthamiana seedlings treated with an autophagy inhibitor and in autophagy-related (ATG) gene-silenced N. benthamiana and in Arabidopsis atg mutants. Autophagic activity in the leaves responded to the dynamic starch contents during the night. Microscopy showed that a type of small starch granule-like structure (SSGL) was localized outside the chloroplast and was sequestered by autophagic bodies. Moreover, an increased number of SSGLs was observed during starch depletion, and disruption of autophagy reduced the number of vacuole-localized SSGLs. These data suggest that autophagy contributes to transitory starch degradation by sequestering SSGLs to the vacuole for their subsequent breakdown. PMID:23564204

  17. Intact endothelial autophagy is required to maintain vascular lipid homeostasis.

    PubMed

    Torisu, Kumiko; Singh, Krishna K; Torisu, Takehiro; Lovren, Fina; Liu, Jie; Pan, Yi; Quan, Adrian; Ramadan, Azza; Al-Omran, Mohammed; Pankova, Natalie; Boyd, Shelley R; Verma, Subodh; Finkel, Toren

    2016-02-01

    The physiological role of autophagic flux within the vascular endothelial layer remains poorly understood. Here, we show that in primary endothelial cells, oxidized and native LDL stimulates autophagosome formation. Moreover, by both confocal and electron microscopy, excess native or modified LDL appears to be engulfed within autophagic structures. Transient knockdown of the essential autophagy gene ATG7 resulted in higher levels of intracellular (125) I-LDL and oxidized LDL (OxLDL) accumulation, suggesting that in endothelial cells, autophagy may represent an important mechanism to regulate excess, exogenous lipids. The physiological importance of these observations was assessed using mice containing a conditional deletion of ATG7 within the endothelium. Following acute intravenous infusion of fluorescently labeled OxLDL, mice lacking endothelial expression of ATG7 demonstrated prolonged retention of OxLDL within the retinal pigment epithelium (RPE) and choroidal endothelium of the eye. In a chronic model of lipid excess, we analyzed atherosclerotic burden in ApoE(-/-) mice with or without endothelial autophagic flux. The absence of endothelial autophagy markedly increased atherosclerotic burden. Thus, in both an acute and chronic in vivo model, endothelial autophagy appears critically important in limiting lipid accumulation within the vessel wall. As such, strategies that stimulate autophagy, or prevent the age-dependent decline in autophagic flux, might be particularly beneficial in treating atherosclerotic vascular disease. PMID:26780888

  18. Autophagy precedes apoptosis during the remodeling of silkworm larval midgut.

    PubMed

    Franzetti, Eleonora; Huang, Zhi-Jun; Shi, Yan-Xia; Xie, Kun; Deng, Xiao-Juan; Li, Jian-Ping; Li, Qing-Rong; Yang, Wan-Ying; Zeng, Wen-Nian; Casartelli, Morena; Deng, Hui-Min; Cappellozza, Silvia; Grimaldi, Annalisa; Xia, Qingyou; Feng, Qili; Cao, Yang; Tettamanti, Gianluca

    2012-03-01

    Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis, solid experimental evidence for autophagy is still lacking. Moreover, the role of the two processes and the nature of their relationship are still cryptic. In this study, we perform a cellular, biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation, with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions. We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms, which occur at different times and have different functions. Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages, as demonstrated by specific autophagic markers. Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period. Apoptosis intervenes later. In fact, although genes encoding caspases are transcribed at the end of the larval period, the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase. The abundance of apoptotic features during the pupal phase, when the majority of the cells die, indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells. PMID:22127643

  19. Pollination induces autophagy in petunia petals via ethylene

    PubMed Central

    Shibuya, Kenichi

    2013-01-01

    Autophagy is one of the main mechanisms of degradation and remobilization of macromolecules, and it appears to play an important role in petal senescence. However, little is known about the regulatory mechanisms of autophagy in petal senescence. Autophagic processes were observed by electron microscopy and monodansylcadaverine staining of senescing petals of petunia (Petunia hybrida); autophagy-related gene 8 (ATG8) homologues were isolated from petunia and the regulation of expression was analysed. Nutrient remobilization was also examined during pollination-induced petal senescence. Active autophagic processes were observed in the mesophyll cells of senescing petunia petals. Pollination induced the expression of PhATG8 homologues and was accompanied by an increase in ethylene production. Ethylene inhibitor treatment in pollinated flowers delayed the induction of PhATG8 homologues, and ethylene treatment rapidly upregulated PhATG8 homologues in petunia petals. Dry weight and nitrogen content were decreased in the petals and increased in the ovaries after pollination in detached flowers. These results indicated that pollination induces autophagy and that ethylene is a key regulator of autophagy in petal senescence of petunia. The data also demonstrated the translocation of nutrients from the petals to the ovaries during pollination-induced petal senescence. PMID:23349142

  20. Pollination induces autophagy in petunia petals via ethylene.

    PubMed

    Shibuya, Kenichi; Niki, Tomoko; Ichimura, Kazuo

    2013-02-01

    Autophagy is one of the main mechanisms of degradation and remobilization of macromolecules, and it appears to play an important role in petal senescence. However, little is known about the regulatory mechanisms of autophagy in petal senescence. Autophagic processes were observed by electron microscopy and monodansylcadaverine staining of senescing petals of petunia (Petunia hybrida); autophagy-related gene 8 (ATG8) homologues were isolated from petunia and the regulation of expression was analysed. Nutrient remobilization was also examined during pollination-induced petal senescence. Active autophagic processes were observed in the mesophyll cells of senescing petunia petals. Pollination induced the expression of PhATG8 homologues and was accompanied by an increase in ethylene production. Ethylene inhibitor treatment in pollinated flowers delayed the induction of PhATG8 homologues, and ethylene treatment rapidly upregulated PhATG8 homologues in petunia petals. Dry weight and nitrogen content were decreased in the petals and increased in the ovaries after pollination in detached flowers. These results indicated that pollination induces autophagy and that ethylene is a key regulator of autophagy in petal senescence of petunia. The data also demonstrated the translocation of nutrients from the petals to the ovaries during pollination-induced petal senescence. PMID:23349142

  1. Autophagy-mediated longevity is modulated by lipoprotein biogenesis

    PubMed Central

    Seah, Nicole E.; de Magalhaes Filho, C. Daniel; Petrashen, Anna P.; Henderson, Hope R.; Laguer, Jade; Gonzalez, Julissa; Dillin, Andrew; Hansen, Malene; Lapierre, Louis R.

    2016-01-01

    ABSTRACT Autophagy-dependent longevity models in C. elegans display altered lipid storage profiles, but the contribution of lipid distribution to life-span extension is not fully understood. Here we report that lipoprotein production, autophagy and lysosomal lipolysis are linked to modulate life span in a conserved fashion. We find that overexpression of the yolk lipoprotein VIT/vitellogenin reduces the life span of long-lived animals by impairing the induction of autophagy-related and lysosomal genes necessary for longevity. Accordingly, reducing vitellogenesis increases life span via induction of autophagy and lysosomal lipolysis. Life-span extension due to reduced vitellogenesis or enhanced lysosomal lipolysis requires nuclear hormone receptors (NHRs) NHR-49 and NHR-80, highlighting novel roles for these NHRs in lysosomal lipid signaling. In dietary-restricted worms and mice, expression of VIT and hepatic APOB (apolipoprotein B), respectively, are significantly reduced, suggesting a conserved longevity mechanism. Altogether, our study demonstrates that lipoprotein biogenesis is an important mechanism that modulates aging by impairing autophagy and lysosomal lipolysis. PMID:26671266

  2. Translational Control of Autophagy by Orb in the Drosophila Germline.

    PubMed

    Rojas-Ríos, Patricia; Chartier, Aymeric; Pierson, Stéphanie; Séverac, Dany; Dantec, Christelle; Busseau, Isabelle; Simonelig, Martine

    2015-12-01

    Drosophila Orb, the homolog of vertebrate CPEB, is a key translational regulator involved in oocyte polarity and maturation through poly(A) tail elongation of specific mRNAs. orb also has an essential function during early oogenesis that has not been addressed at the molecular level. Here, we show that orb prevents cell death during early oogenesis, thus allowing oogenesis to progress. It does so through the repression of autophagy by directly repressing, together with the CCR4 deadenylase, the translation of Autophagy-specific gene 12 (Atg12) mRNA. Autophagy and cell death observed in orb mutant ovaries are reduced by decreasing Atg12 or other Atg mRNA levels. These results reveal a role of Orb in translational repression and identify autophagy as an essential pathway regulated by Orb during early oogenesis. Importantly, they also establish translational regulation as a major mode of control of autophagy, a key process in cell homeostasis in response to environmental cues. PMID:26625957

  3. Targeting autophagy in breast cancer

    PubMed Central

    Maycotte, Paola; Thorburn, Andrew

    2014-01-01

    Macroautophagy (referred to as autophagy here) is an intracellular degradation pathway enhanced in response to a variety of stresses and in response to nutrient deprivation. This process provides the cell with nutrients and energy by degrading aggregated and damaged proteins as well as compromised organelles. Since autophagy has been linked to diverse diseases including cancer, it has recently become a very interesting target in breast cancer treatment. Indeed, current clinical trials are trying to use chloroquine or hydroxychloroquine, alone or in combination with other drugs to inhibit autophagy during breast cancer therapy since chemotherapy and radiation, regimens that are used to treat breast cancer, are known to induce autophagy in cancer cells. Importantly, in breast cancer, autophagy has been involved in the development of resistance to chemotherapy and to anti-estrogens. Moreover, a close relationship has recently been described between autophagy and the HER2 receptor. Here, we discuss some of the recent findings relating autophagy and cancer with a particular focus on breast cancer therapy. PMID:25114840

  4. Autophagy in Plasma Cell Pathophysiology

    PubMed Central

    Oliva, Laura; Cenci, Simone

    2014-01-01

    Plasma cells (PCs) are the effectors responsible for antibody (Ab)-mediated immunity. They differentiate from B lymphocytes through a complete remodeling of their original structure and function. Stress is a constitutive element of PC differentiation. Macroautophagy, conventionally referred to as autophagy, is a conserved lysosomal recycling strategy that integrates cellular metabolism and enables adaptation to stress. In metazoa, autophagy plays diverse roles in cell differentiation. Recently, a number of autophagic functions have been recognized in innate and adaptive immunity, including clearance of intracellular pathogens, inflammasome regulation, lymphocyte ontogenesis, and antigen presentation. We identified a previously unrecognized role played by autophagy in PC differentiation and activity. Following B cell activation, autophagy moderates the expression of the transcriptional repressor Blimp-1 and immunoglobulins through a selective negative control exerted on the size of the endoplasmic reticulum and its stress signaling response, including the essential PC transcription factor, XBP-1. This containment of PC differentiation and function, i.e., Ab production, is essential to optimize energy metabolism and viability. As a result, autophagy sustains Ab responses in vivo. Moreover, autophagy is an essential intrinsic determinant of long-lived PCs in their as yet poorly understood bone marrow niche. In this essay, we discuss these findings in the context of the established biological functions of autophagy, and their manifold implications for adaptive immunity and PC diseases, in primis multiple myeloma. PMID:24659989

  5. Cilostazol Upregulates Autophagy via SIRT1 Activation: Reducing Amyloid-β Peptide and APP-CTFβ Levels in Neuronal Cells

    PubMed Central

    Lee, Hye Rin; Shin, Hwa Kyoung; Park, So Youn; Kim, Hye Young; Bae, Sun Sik; Lee, Won Suk; Rhim, Byung Yong; Hong, Ki Whan; Kim, Chi Dae

    2015-01-01

    Autophagy is a