Role of lipids in the control of autophagy and primary cilium signaling in neurons

The brain is,after the adipose tissue,the organ with the greatest amount of lipids and diversity in their composition in the human body.In neurons,lipids are involved in signaling pathways controlling autophagy,a lysosome-dependent catabolic process essential for the maintenance of neuronal homeostasis and the function of the primary cilium,a cellular antenna that acts as a communication hub that transfers extracellular signals into intracellular responses required for neurogenesis and brain development.A crosstalk between primary cilia and autophagy has been established;however,its role in the control of neuronal activity and homeostasis is barely known.In this review,we briefly discuss the current knowledge regarding the role of autophagy and the primary cilium in neurons.Then we review the recent literature about specific lipid subclasses in the regulation of autophagy,in the control of primary cilium structure and its dependent cellular signaling in physiological and pathological conditions,specifically focusing on neurons,an area of research that could have major implications in neurodevelopment,energy homeostasis,and neurodegeneration.

From macroautophagy to mitophagy:Unveiling the hidden role of mitophagy in gastrointestinal disorders

In this editorial,we comment on an article titled“Morphological and biochemical characteristics associated with autophagy in gastrointestinal diseases”,which was published in a recent issue of the World Journal of Gastroenterology.We focused on the statement that“autophagy is closely related to the digestion,secretion,and regeneration of gastrointestinal cells”.With advancing research,autophagy,and particularly the pivotal role of the macroautophagy in maintaining cellular equilibrium and stress response in the gastrointestinal system,has garnered extensive study.However,the significance of mitophagy,a unique selective autophagy pathway with ubiquitin-dependent and independent variants,should not be overlooked.In recent decades,mitophagy has been shown to be closely related to the occurrence and development of gastrointestinal diseases,especially inflammatory bowel disease,gastric cancer,and colorectal cancer.The interplay between mitophagy and mitochondrial quality control is crucial for elucidating disease mechanisms,as well as for the development of novel treatment strategies.Exploring the pathogenesis behind gastrointestinal diseases and providing individualized and efficient treatment for patients are subjects we have been exploring.This article reviews the potential mechanism of mitophagy in gastrointestinal diseases with the hope of providing new ideas for diagnosis and treatment.

Pterostilbene attenuates intrauterine growth retardation-induced colon inflamm tion in piglets by modulating endoplasmic reticulum stress and autophagy

Background:Endoplasmic reticulum(ER)stress and autophagy are implicated in the pathophysiology of intestinal inflammation;however,their roles in intrauterine growth retardation(IUGR)-induced colon inflammation are unclear.This study explored the protective effects of natural stilbene pterostilbene on colon inflammation using the IUGR piglets and the tumor necrosis factor alpha(TNF-α)-treated human colonic epithelial cells(Caco-2)by targeting ER stress and autophagy.Results:Both the IUGR colon and the TNF-α-treated Caco-2 cells exhibited inflammatory responses,ER stress,and impaired autophagic flux(P<0.05).The ER stress inducer tunicamycin and the autophagy inhibitor 3-methyladenine further augmented inflammatory responses and apoptosis in the TNF-α-treated Caco-2 cells(P<0.05).Conversely,pterostilbene inhibited ER stress and restored autophagic flux in the IUGR colon and the TNF-α-treated cells(P<0.05).Pterostilbene also prevented the release of inflammatory cytokines and nuclear translocation of nuclear factor kappa B p65,reduced intestinal permeability and cell apoptosis,and facilitated the expression of intestinal tight junction proteins in the IUGR colon and the TNF-α-treated cells(P<0.05).Importantly,treatment with tunicamycin or autophagosome-lysosome binding inhibitor chloroquine blocked the positive effects of pterostilbene on inflammatory response,cell apoptosis,and intestinal barrier function in the TNF-α-exposed Caco-2 cells(P<0.05).Conclusion:Pterostilbene mitigates ER stress and promotes autophagic flux,thereby improving colon inflammation and barrier dysfunction in the IUGR piglets and the TNF-α-treated Caco-2 cells.

Suberoylanilide hydroxamic acid upregulates reticulophagy receptor expression and promotes cell death in hepatocellular carcinoma cells

BACKGROUND Hepatocellular carcinoma(HCC)is a common clinical condition with a poor prognosis and few effective treatment options.Potent anticancer agents for treating HCC must be identified.Epigenetics plays an essential role in HCC tumorigenesis.Suberoylanilide hydroxamic acid(SAHA),the most common histone deacetylase inhibitor agent,triggers many forms of cell death in HCC.However,the underlying mechanism of action remains unclear.Family with sequence similarity 134 member B(FAM134B)-induced reticulophagy,a selective autophagic pathway,participates in the decision of cell fate and exhibits anticancer activity.This study focused on the relationship between FAM134B-induced reticulophagy and SAHA-mediated cell death.AIM To elucidate potential roles and underlying molecular mechanisms of reticulophagy in SAHA-induced HCC cell death.METHODS The viability,apoptosis,cell cycle,migration,and invasion of SAHA-treated Huh7 and MHCC97L cells were measured.Proteins related to the reticulophagy pathway,mitochondria-endoplasmic reticulum(ER)contact sites,intrinsic mitochondrial apoptosis,and histone acetylation were quantified using western blotting.ER and lysosome colocalization,and mitochondrial Ca^(2+)levels were characterized via confocal microscopy.The level of cell death was evaluated through Hoechst 33342 staining and propidium iodide colocalization.Chromatin immunoprecipitation was used to verify histone H4 lysine-16 acetylation in the FAM134B promoter region.RESULTS After SAHA treatment,the proliferation of Huh7 and MHCC97L cells was significantly inhibited,and the migration and invasion abilities were greatly blocked in vitro.This promoted apoptosis and caused G1 phase cells to increase in a concentration-dependent manner.Following treatment with SAHA,ER-phagy was activated,thereby triggering autophagy-mediated cell death of HCC cells in vitro.Western blotting and chromatin immunoprecipitation assays confirmed that SAHA regulated FAM134B expression by enhancing the histone H4 lysine-16 acetylation in the FAM134B promoter region.Further,SAHA disturbed the Ca^(2+)homeostasis and upregulated the level of autocrine motility factor receptor and proteins related to mitochondria-endoplasmic reticulum contact sites in HCC cells.Additionally,SAHA decreased the mitochondrial membrane potential levels,thereby accelerating the activation of the reticulophagy-mediated mitochondrial apoptosis pathway and promoting HCC cell death in vitro.CONCLUSION SAHA stimulates FAM134B-mediated ER-phagy to synergistically enhance the mitochondrial apoptotic pathway,thereby enhancing HCC cell death.

Neuronal autophagy aggravates microglial inflammatory injury by downregulating CX3CL1/fractalkine after ischemic stroke

Ischemic stroke often induces excessive neuronal autophagy, resulting in brain damage; meanwhile, inflammatory responses stimulated by ischemia exacerbate neural injury. However, interactions between neuronal autophagy and microglial inflammation following ischemic stroke are poorly understood. CX3CL1/fractalkine, a membrane-bound chemokine expressed on neurons, can suppress microglial inflammation by binding to its receptor CX3CR1 on microglia. In the present study, to investigate whether autophagy could alter CX3CL1 expression on neurons and consequently change microglial inflammatory activity, middle cerebral artery occlusion(MCAO) was established in Sprague-Dawley rats to model ischemic stroke, and tissues from the ischemic penumbra were obtained to evaluate autophagy level and microglial inflammatory activity. MCAO rats were administered 3-methyladenine(autophagy inhibitor) or Tat-Beclin 1(autophagy inducer). Western blot assays were conducted to quantify expression of Beclin-1, nuclear factor kappa Bp65(NF-κB), light chain 3B(LC3B), and CX3CL1 in ischemic penumbra. Moreover, immunofluorescence staining was performed to quantify numbers of LC3B-, CX3CL1-, and Iba-1-positive cells in ischemic penumbra. In addition, enzyme linked immunosorbent assays were utilized to analyze concentrations of tumor necrosis factor alpha(TNF-α), interleukin 6(IL-6), interleukin 1 beta(IL-1β), and prostaglandin E2(PGE2). A dry/wet weight method was used to detect brain water content, while 2,3,5,-triphenyltetrazolium chloride staining was utilized to measure infarct volume. The results demonstrated that autophagy signaling(Beclin-1 and LC3B expression) in penumbra was prominently activated by MCAO, while CX3CL1 expression on autophagic neurons was significantly reduced and microglial inflammation was markedly activated. However, after inhibition of autophagy signaling with 3-methyladenine, CX3CL1 expression on neurons was obviously increased, whereas Iba-1 and NF-κB expression was downregulated; TNF-α, IL-6, IL-1β, and PGE2 levels were decreased; and cerebral edema was obviously mitigated. In contrast, after treatment with the autophagy inducer Tat-Beclin 1, CX3CL1 expression on neurons was further reduced; Iba-1 and NF-κB expression was increased; TNF-α, IL-6, IL-1β, and PGE2 levels were enhanced; and cerebral edema was aggravated. Our study suggests that ischemia-induced neuronal autophagy facilitates microglial inflammatory injury after ischemic stroke, and the efficacy of this process may be associated with downregulated CX3CL1 expression on autophagic neurons.

Autophagy activation by Jiang Zhi Granule protects against metabolic stress-induced hepatocyte injury

AIM To elucidate the potential role of autophagy and the protective effects of Jiang Zhi Granule(JZG) in metabolic stress-induced hepatocyte injury.METHODS An in vitro and in vivo approach was used in this study. Hep G2 cells were incubated in culture medium containing palmitate(PA; 0, 0.1, 0.2, 0.3, 0.4 or 0.5 mmol/L) and treated with or without JZG(100 μg/m L) for 24 h or 48 h, and the progression of autophagy was visualized by stable fluorescence-expressing cell lines LC3 and p62. Western blot analyses were performed to examine the expression of LC3-Ⅱ/LC3-Ⅰ, p62, m TOR and PI3 K, while mitochondrial integrity and oxidative stress were observed by fluorescence staining of JC-1 and reactive oxygen species. C57 BL/6 mice were divided into three groups: control group(n = 10), high fat(HF) group(n = 13) and JZG group(n = 13); and, histological staining was carried out to detect inflammation and lipid content in the liver.RESULTS The cell trauma induced by PA was aggravated in a dose-and time-dependent manner, and hepatic function was improved by JZG. PA had dual effects on autophagy by activating autophagy induction and blocking autophagic flux. The PI3 K-AKT-m TOR signaling pathway and the fusion of isolated hepatic autophagosomes and lysosomes were critically involved in this process. JZG activated autophagy progression by either induction of autophagosomes or co-localization of autophagosomes and lysosomes as well as degradation of autolysosomes to protect against PA-induced hepatocyte injury, and protected mitochondrial integrity against oxidative stress in PA-induced mitochondrial dysfunction. In addition, JZG ameliorated lipid droplets and inflammation induced by HF diet in vivo, leading to improved metabolic disorder and associated liver injury in a mouse model of non-alcoholic fatty liver disease(NAFLD).CONCLUSION Metabolic stress-induced hepatocyte injury exhibited dual effects on autophagy and JZG activated the entire process, resulting in beneficial effects in NAFLD.

Autophagy prevents autophagic cell death in Tetrahymena in response to oxidative stress

Autophagy is a major cellular pathway used to degrade long-lived proteins or organelles that may be damaged due to increased reactive oxygen species（ROS） generated by cellular stress. Autophagy typically enhances cell survival, but it may also act to promote cell death under certain conditions. The mechanism underlying this paradox, however, remains unclear. We showed that Tetrahymena cells exerted increased membranebound vacuoles characteristic of autophagy followed by autophagic cell death（referred to as cell death with autophagy） after exposure to hydrogen peroxide. Inhibition of autophagy by chloroquine or 3-methyladenine significantly augmented autophagic cell death induced by hydrogen peroxide. Blockage of the mitochondrial electron transport chain or starvation triggered activation of autophagy followed by cell death by inducing the production of ROS due to the loss of mitochondrial membrane potential. This indicated a regulatory role of mitochondrial ROS in programming autophagy and autophagic cell death in Tetrahymena. Importantly, suppression of autophagy enhanced autophagic cell death in Tetrahymena in response to elevated ROS production from starvation, and this was reversed by antioxidants. Therefore, our results suggest that autophagy was activated upon oxidative stress to prevent the initiation of autophagic cell death in Tetrahymena until the accumulation of ROS passed the point of no return, leading to delayed cell death in Tetrahymena.

Autophagic cell death induced by reactive oxygen species is involved in hyperthermic sensitization to ionizing radiation in human hepatocellular carcinoma cells

AIM To investigate whether autophagic cell death is involved in hyperthermic sensitization to ionizing radiation in human hepatocellular carcinoma cells, and to explore the underlying mechanism.METHODS Human hepatocellular carcinoma cells were treated with hyperthermia and ionizing radiation. MTT and clonogenic assays were performed to determine cell survival. Cell autophagy was detected using acridine orange staining and flow cytometric analysis, and the expression of autophagy-associated proteins, LC3 and p62, was determined by Western blot analysis. Intracellular reactive oxygen species(ROS) were quantified using the fluorescent probe DCFH-DA.RESULTS Treatment with hyperthermia and ionizing radiation significantly decreased cell viability and surviving fraction as compared with hyperthermia or ionizing radiation alone. Cell autophagy was significantly increased after ionizing radiation combined with hyperthermia treatment, as evidenced by increased formation of acidic vesicular organelles, increased expression of LC3 II and decreased expression of p62. Intracellular ROS were also increased after combined treatment with hyperthermia and ionizing radiation. Pretreatment with N-acetylcysteine, an ROS scavenger, markedly inhibited the cytotoxicity and cell autophagy induced by hyperthermia and ionizing radiation.CONCLUSION Autophagic cell death is involved in hyperthermic sensitization of cancer cells to ionizing radiation, and its induction may be due to the increased intracellular ROS.

DJ-1 Activation Raf/ERK Pathways Promotes Autophagy Maturation of PC-12 Cells

Park 7 gene encodes a conserved protein called DJ-1 protein, which involves autophagy stress, but the mechanism is unclear. Therefore, it is necessary to explore the mechanism of DJ-1 regulation PC-12 autophagical stress. Using CRISPR/Cas9 technique to construct DJ-1 knockout PC-12 cell lines, we culture wild-type and DJ-1 knockout PC-12 cell lines, establish oxidative stress cell model by MPP+, and divide them into wild-type control group (WT), wild-type intervention group (WT + MPP+), DJ-1 knockout control group (KO) and DJ-1 knockout intervention group (KO + MPP+), and explore the role of DJ-1 in regulating neuronal autophagy stress by cell viability assay, immunofluorescence, confocal, western blotting and electron microscopy. The results show that the growth ability of DJ-1 knockout cells is inferior to that of normal cells, and DJ-1 knockout cells are more sensitive to oxidative stress and more vulnerable to damage than wild-type cells. Exposing to MPP+, DJ-1 proteins undergo oxidative responses at Cys-106 sites, while DJ-1 knockout PC-12 cells do not show similar responses. The wild-type PC-12 cells have the confocal in both anti-oxidant DJ-1 antibody and anti-C-Raf phosphorylation antibody. The activated DJ-1 induces the phosphorylation of C-Raf at Ser338 sites to activate directly C-Raf, and subsequently activates ERK1/2 signaling pathways to antagonize MPP+-induced neurotoxicity. Lack of DJ-1, oxidative stress can not promote C-Raf activation. Although the phosphorylation level of cell ERK is also increased, the increase of intranucleus pERK is not obvious. Wild type and DJ-1 knockout PC-12 cells can produce autophagical stress in the face of oxidative stress, but the proportion of autophagolysosomes produced in wild type PC-12 cells is larger than that in DJ-1 knockout cells. PD98059 can reduce autophagy stress in the state of oxidative stress in wild-type PC-12 cells, and the number of autophagolysosomes is similarly reduced, while sorafenib decreased slightly DJ-1 the autophagical stress, and the proportion of autophagolysosomes decreased more. Therefore, we can infer that activated DJ-1 directly phosphorylates C-Raf at Ser-338 sites, then activating C-Raf, subsequent activation of the MEK/ERK pathway. DJ-1 promotes autophagy maturation through the C-Raf/ERK pathway, thereby improving cell survival.

Hernandezine promotes cancer cell apoptosis and disrupts the lysosomal acidic environment and cathepsin D maturation

Hernandezine(Her),a bisbenzylisoquinoline alkaloid extracted from Thalictrum flavum,is recognized for its range of biological activities inherent to this herbal medicine.Despite its notable properties,the anti-cancer effects of Her have remained largely unexplored.In this study,we elucidated that Her significantly induced cytotoxicity in cancer cells through the activation of apoptosis and necroptosis mechanisms.Furthermore,Her triggered autophagosome formation by activating the AMPK and ATG5 conjugation systems,leading to LC3 lipidation.Our findings revealed that Her caused damage to the mitochondrial membrane,with the damaged mitochondria undergoing mitophagy,as evidenced by the elevated expression of mitophagy markers.Conversely,Her disrupted autophagic flux,demonstrated by the upregulation of p62 and accumulation of autolysosomes,as observed in the RFP-GFP-LC3 reporter assay.Initially,we determined that Her did not prevent the fusion of autophagosomes and lysosomes.However,it inhibited the maturation of cathepsin D and increased lysosomal pH,indicating an impairment of lysosomal function.The use of the early-stage autophagy inhibitor,3-methyladenine(3-MA),did not suppress LC3II,suggesting that Her also induces noncanonical autophagy in autophagosome formation.The application of Bafilomycin A1,an inhibitor of noncanonical autophagy,diminished the recruitment of ATG16L1 and the accumulation of LC3II by Her,thereby augmenting Her-induced cell death.These observations imply that while autophagy initially plays a protective role,the disruption of the autophagic process by Her promotes programmed cell death.This study provides the first evidence of Her’s dual role in inducing apoptosis and necroptosis while also initiating and subsequently impairing autophagy to promote apoptotic cell death.These insights contribute to a deeper understanding of the mechanisms underlying programmed cell death,offering potential avenues for enhancing cancer prevention and therapeutic strategies.

Retinoic acid alleviates rotavirus-induced intestinal damage by regulating redox homeostasis and autophagic flux in piglets

Rotaviruses(RV)are a major cause of severe gastroenteritis,particularly in neonatal piglets.Despite the availability of effective vaccines,the development of antiviral therapies for RV remains an ongoing challenge.Retinoic acid(RA),a metabolite of vitamin A,has been shown to have anti-oxidative and antiviral properties.However,the mechanism by which RA exerts its intestinal-protective and antiviral effects on RV infection is not fully understood.The study investigates the effects of RA supplementation in Duroc×Landrace×Yorkshire(DLY)piglets challenged with RV.Thirty-six DLY piglets were assigned into six treatments,including a control group,RA treatment group with two concentration gradients(5and 15 mg/d),RV treatment group,and RV treatment group with the addition of different concentration gradients of RA(5 and 15 mg/d).Our study revealed that RV infection led to extensive intestinal architecture damage,which was mitigated by RA treatment at lower concentrations by increasing the villus height and villus height/crypt depth ratio(P<0.05),enhancing intestinal stem cell signaling and promoting intestinal barrier functions.In addition,15 mg/d RA supplementation significantly increased NRF2 and HO-1 protein expression(P<0.05)and GSH content(P<0.05),indicating that RA supplementation can enhance anti-oxidative signaling and redox homeostasis after RV challenge.Additionally,the research demonstrated that RA exerts a dual impact on the regulation of autophagy,both stimulating the initiation of autophagy and hindering the flow of autophagic flux.Through the modulation of autophagic flux,RA influence the progression of RV infection.These findings provide new insights into the regulation of redox hemostasis and autophagy by RA and its potential therapeutic application in RV infection.

Vaspin alleviates pathological cardiac hypertrophy by regulating autophagy-dependent myocardial senescence

Background:Visceral adipose tissue-derived serine protease inhibitor(vaspin),a secretory adipokine,protects against insulin resistance.Recent studies have demonstrated that serum vaspin levels are decreased in patients with coronary artery disease and that vaspin protects against myocardial ischemia-reperfusion injury and atherosclerosis.However,it remains unclear whether vaspin exerts specific effects on pathological cardiac hypertrophy.Methods:An in vivo study was conducted using a cardiac hypertrophy model established by subcutaneous injection of isoproterenol(ISO)in C57BL/6 and vaspin-ko mice.Rapamycin was administered intraperitoneally to mice,for further study.H9c2 cells and neonatal rat ventricular myocytes(NRVMs)were treated with ISO to induce hypertrophy.Human vaspin fusion protein,the proteasome inhibitor MG132,and chloroquine diphosphate were used for further mechanistic studies.Results:Here,we provide the first evidence that vaspin knockdown results in markedly exaggerated cardiac hypertrophy,fibrosis,and cardiomyocyte senescence in mice treated with ISO.Conversely,the administration of exogenous recombinant human vaspin protected NRVMs in vitro against ISO-induced hypertrophy and senescence.Furthermore,vaspin significantly potentiated the ISO-induced decrease in autophagy.Both rapamycin and chloroquine diphosphate regulated autophagy in vivo and in vitro,respectively,and participated in vaspin-mediated cardioprotection.Moreover,the PI3K-AKT-mTOR pathway plays a critical role in vaspin-mediated autophagy in cardiac tissues and NRVMs.Our data showed that vaspin downregulated the p85 and p110 subunits of PI3K by linking p85 and p110 to NEDD4L-mediated ubiquitination degradation.Conclusion:Our results show,for the first time,that vaspin functions as a critical regulator that alleviates pathological cardiac hypertrophy by regulating autophagy-dependent myocardial senescence,providing potential preventive and therapeutic targets for pathological cardiac hypertrophy.

Engineering cannabidiol synergistic carbon monoxide nanocomplexes to enhance cancer therapy via excessive autophagy

Although carbon monoxide(CO)-based treatments have demonstrated the high cancer efficacy by promoting mitochondrial damage and core-region penetrating ability,the efficiency was often compromised by protective autophagy(mitophagy).Herein,cannabidiol(CBD)is integrated into biomimetic carbon monoxide nanocomplexes(HMPOC@M)to address this issue by inducing excessive autophagy.The biomimetic membrane not only prevents premature drugs leakage,but also prolongs blood circulation for tumor enrichment.After entering the acidic tumor microenvironment,carbon monoxide(CO)donors are stimulated by hydrogen oxide(H_(2)O_(2))to disintegrate into CO and Mn^(2+).The comprehensive effect of CO/Mn^(2+)and CBD can induce ROS-mediated cell apoptosis.In addition,HMPOC@Mmediated excessive autophagy can promote cancer cell death by increasing autophagic flux via classⅢPI3K/BECN1 complex activation and blocking autolysosome degradation via LAMP1 downregulation.Furthermore,in vivo experiments showed that HMPOC@M+laser strongly inhibited tumor growth and attenuated liver and lung metastases by downregulating VEGF and MMP9 proteins.This strategy may highlight the pro-death role of excessive autophagy in TNBC treatment,providing a novel yet versatile avenue to enhance the efficacy of CO treatments.Importantly,this work also indicated the applicability of CBD for triple-negative breast cancer(TNBC)therapy through excessive autophagy.

Autophagic activity in neuronal cell death

As post-mitotic cells with great energy demands, neurons depend upon the homeostatic and waste-recycling functions provided by autophagy. In addition, autophagy also promotes survival during periods of harsh stress and targets aggregate-prone proteins associated with neurodegeneration for degradation. Despite this, autophagy has also been controversially described as a mechanism of programmed cell death. Instances of autophagic cell death are typically associated with elevated numbers of cytoplasmic autophagosomes, which have been assumed to lead to excessive degradation of cellular components. Due to the high activity and reliance on autophagy in neurons, these cells may be particularly susceptible to autophagic death. In this review, we summarize and assess current evidence in support of autophagic cell death in neurons, as well as how the dysregulation of autophagy commonly seen in neurodegeneration can contribute to neuron loss. From here, we discuss potential treatment strategies relevant to such cell-death pathways.

Preliminary evidence for the presence of multiple forms of cell death in diabetes cardiomyopathy

Diabetic mellitus(DM) is a common degenerative chronic metabolic disease often accompanied by severe cardiovascular complications(DCCs) as major causes of death in diabetic patients with diabetic cardiomyopathy(DCM) as the most common DCC. The metabolic disturbance in DCM generates the conditions/substrates and inducers/triggers and activates the signaling molecules and death executioners leading to cardiomyocyte death which accelerates the development of DCM and the degeneration of DCM to heart failure.Various forms of programmed active cell death including apoptosis, pyroptosis, autophagic cell death, autosis,necroptosis, ferroptosis and entosis have been identified and characterized in many types of cardiac disease.Evidence has also been obtained for the presence of multiple forms of cell death in DCM. Most importantly,published animal experiments have demonstrated that suppression of cardiomyocyte death of any forms yields tremendous protective effects on DCM. Herein, we provide the most updated data on the subject of cell death in DCM, critical analysis of published results focusing on the pathophysiological roles of cell death, and pertinent perspectives of future studies.

Neuroprotective Autophagic Flux Induced by Hyperbaric Oxygen Preconditioning is Mediated by Cystatin C

We have previously reported that Cystatin C(CysC) is a pivotal mediator in the neuroprotection induced by hyperbaric oxygen(HBO) preconditioning; however,the underlying mechanism and how CysC changes after stroke are not clear. In the present study, we demonstrated that CysC expression was elevated as early as 3 h after reperfusion, and this was further enhanced by HBO preconditioning. Concurrently, LC3-II and Beclin-1, two positive-markers for autophagy induction, exhibited increases similar to CysC, while knockdown of CysC blocked these elevations. As a marker of autophagy inhibition, p62 was downregulated by HBO preconditioning and this was blocked by CysC knockdown. Besides, the beneficial effects of preserving lysosomal membrane integrity and enhancing autolysosome formation induced by HBO preconditioning were abolished in CysC-/-rats.Furthermore, we demonstrated that exogenous CysC reduced the neurological deficits and infarct volume after brain ischemic injury, while 3-methyladenine partially reversed this neuroprotection. In the present study, we showed that CysC is biochemically and morphologically essential for promoting autophagic flux, and highlighted the translational potential of HBO preconditioning and CysC for stroke treatment.

Actively priming autophagic cell death with novel transferrin receptor-targeted nanomedicine for synergistic chemotherapy against breast cancer

Recently, considerable attention in the field of cancer therapy has been focused on the mammalian rapamycin target(m TOR), inhibition of which could result in autophagic cell death(ACD). Though novel combination chemotherapy of autophagy inducers with chemotherapeutic agents is extensively investigated, nanomedicine-based combination therapy for ACD remains in infancy. In attempt to actively trigger ACD for synergistic chemotherapy, here we incorporated autophagy inducer rapamycin(RAP) into 7 pep-modified PEG-DSPE polymer micelles(7 pep-M-RAP) to specifically target and efficiently priming ACD of MCF-7 human breast cancer cells with high expression of transferrin receptor(Tf R). Cytotoxic paclitaxel(PTX)-loaded micelle(7 pep-M-PTX) was regarded as chemotherapeutic drug model. We discovered that with superior intracellular uptake in vitro and more tumor accumulation of micelles in vivo, 7 pep-M-RAP exhibited excellent autophagy induction and synergistic antitumor efficacy with 7 pep-M-PTX. Mechanism study further revealed that 7 pep-M-RAP and 7 pep-MPTX used in combination provided enhanced efficacy through induction of both apoptosis-and mitochondria-associated autophagic cell death. Together, our findings suggested that the targeted excess autophagy may provide a rational strategy to improve therapeutic outcome of breast cancer, and simultaneous induction of ACD and apoptosis may be a promising anticancer modality.

Loss of VAPB Regulates Autophagy in a Beclin 1-Dependent Manner

Autophagy is an evolutionarily-conserved selfdegradative process that maintains cellular homeostasis by eliminating protein aggregates and damaged organelles.Recently, vesicle-associated membrane protein-associated protein B(VAPB), which is associated with the familial form of amyotrophic lateral sclerosis, has been shown to regulate autophagy. In the present study, we demonstrated that knockdown of VAPB induced the up-regulation of beclin 1 expression, which promoted LC3(microtubuleassociated protein light chain 3) conversion and the formation of LC3 puncta, whereas overexpression of VAPB inhibited these processes. The regulation of beclin1 by VAPB was at the transcriptional level. Moreover,knockdown of VAPB increased autophagic flux, which promoted the degradation of the autophagy substrate p62 and neurodegenerative disease proteins. Our study provides evidence that the regulation of autophagy by VAPB is associated with the autophagy-initiating factor beclin 1.

STING signaling activation inhibits HBV replication and attenuates the severity of liver injury and HBV-induced fibrosis

The covalently closed circular DNA(cccDNA)of HBV plays a crucial role in viral persistence and is also a risk factor for developing HBV-induced diseases,including liver fibrosis.Stimulator of interferon genes(STING),a master regulator of DNA-mediated innate immune activation,is a potential therapeutic target for viral infection and virus-related diseases.In this study,agonist-induced STING signaling activation in macrophages was revealed to inhibit cccDNA-mediated transcription and HBV replication via epigenetic modification in hepatocytes.Notably,STING activation could efficiently attenuate the severity of liver injury and fibrosis in a chronic recombinant cccDNA(rcccDNA)mouse model,which is a proven suitable research platform for HBV-induced fibrosis.Mechanistically,STING-activated autophagic flux could suppress macrophage inflammasome activation,leading to the amelioration of liver injury and HBV-induced fibrosis.Overall,the activation of STING signaling could inhibit HBV replication through epigenetic suppression of cccDNA and alleviate HBV-induced liver fibrosis through the suppression of macrophage inflammasome activation by activating autophagic flux in a chronic HBV mouse model.This study suggests that targeting the STING signaling pathway may be an important therapeutic strategy to protect against persistent HBV replication and HBV-induced fibrosis.

Ginsenoside Rb1 Ameliorates Autophagy of Hypoxia Cardiomyocytes from Neonatal Rats via AMP-Activated Protein Kinase Pathway

Objective: To investigate whether ginsenoside-Rb1(Gs-Rb1) improves the CoCl2-induced autophagy of cardiomyocytes via upregulation of adenosine 5’-monophosphate-activated protein kinase(AMPK) pathway. Methods: Ventricles from 1-to 3-day-old Wistar rats were sequentially digested, separated and incubated in Dulbecco’s modified Eagle’s medium supplemented with 10% fetal bovine serum for 3 days followed by synchronization. Neonatal rat cardiomyocytes were randomly divided into 7 groups: control group(normal level oxygen), hypoxia group(500 μmol/L CoCl2), Gs-Rb1 group(200 μmol/L Gs-Rb1 + 500 μmol/L CoCl2), Ara A group(500 μmol/L Ara A + 500 μmol/L CoCl2), Ara A+ Gs-Rb1 group(500 μmol/L Ara A + 200 μmol/L Gs-Rb1 + 500 μmol/L CoCl2), AICAR group [1 mmol/L 5-aminoimidazole-4-carboxamide ribonucleotide(AICAR)+ 500 μmol/L CoCl2], and AICAR+Gs-Rb1 group(1 mmol/L AICAR + 200 μmol/L Gs-Rb1 + 500 μmol/L CoCl2). Cel s were treated for 12 h and cell viability was determined by methylthiazolyldiphenyl-tetrazolium bromide(MTT) assay and cardiac troponin I(cTnI) levels were detected by enzyme-linked immunosorbent assay(ELISA). AMPK activity was assessed by 2’,7’-dichlorofluorescein diacetate(DCFH-DA) ELISA assay. The protein expressions of Atg4 B, Atg5, Atg6, Atg7, microtubule-associated protein 1 A/1 B-light chain 3(LC3), P62, and active-cathepsin B were measured by Western blot. Results: Gs-Rb1 significantly improved the cell viability of hypoxia cardiomyocytes(P<0.01). However, the viability of hypoxia-treated cardiomyocytes was significantly inhibited by Ara A(P<0.01). Gs-Rb1 increased the AMPK activity of hypoxia-treated cardiomyocytes. The AMPK activity of hypoxia-treated cadiomyocytes was inhibited by Ara A(P<0.01) and was not affected by AICAR(P=0.983). Gs-Rb1 up-regulated Atg4B, Atg5, Beclin-1, Atg7, LC3B Ⅱ, the LC3BⅡ/Ⅰ ratio and cathepsin B activity of hypoxia cardiomyocytes(P<0.05), each of these protein levels was significantly enhanced by Ara A(all P<0.01), but was not affected by AICAR(all P>0.05). Gs-Rb1 significantly down-regulated P62 levels of hypoxic cardiomyocytes(P<0.05). The P62 levels of hypoxic cardiomyocytes were inhibited by Ara A(P<0.05) and were not affected by AICAR(P=0.871). Conclusion: Gs-Rb1 may improve the viability of hypoxia cardiomyocytes by ameliorating cell autophagy via the upregulation of AMPK pathway.