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.

Regulation of autophagic flux by CHIP

Autophagy is a major degradation system which processes substrates through the steps of auto- phagosome formation, autophagosome-lysosome fusion, and substrate degradation. Aberrant autophagic flux is present in many pathological conditions including neurodegeneration and tumors. CHIP/STUB1, an E3 ligase, plays an important role in neurodegeneration. In this study, we identified the regulation of autophagic flux by CHIP （carboxy-terminus of HscT0-interacting protein）. Knockdown of CHIP induced autophagosome formation through increasing the PTEN protein level and decreasing the AKT/mTOR activity as well as decreasing phosphorylation of ULK1 on Ser757. However, degradation of the autophagic substrate p62 was disturbed by knockdown of CHIP, suggesting an abnormality of autophagic flux. Furthermore, knockdown of CHIP increased the susceptibility of cells to autophagic cell death induced by bafilomycin AI. Thus, our data suggest that CHIP plays roles in the regulation of autophagic flux.

Modulating autophagic flux via ROS-responsive targeted micelles to restore neuronal proteostasis in Alzheimer’s disease

Compromised autophagy and defective lysosomal clearance significantly contribute to impaired neuronal proteostasis,which represents a hallmark of Alzheimer’s disease(AD)and other age-related neurodegenerative disorders.Growing evidence has implicated that modulating autophagic flux,instead of inducing autophagosome formation alone,would be more reliable to rescue neuronal proteostasis.Concurrently,selectively enhancing drug concentrations in the leision areas,instead of the whole brain,will maximize therapeutic efficacy while reduing non-selective autophagy induction.Herein,we design a ROS-responsive targeted micelle system(TT-NM/Rapa)to enhance the delivery efficiency of rapamycin to neurons in AD lesions guided by the fusion peptide TPL,and facilitate its intracellular release via ROS-mediated disassembly of micelles,thereby maximizing autophagic flux modulating efficacy of rapamycin in neurons.Consequently,it promotes the efficient clearance of intracellular neurotoxic proteins,β-amyloid and hyperphosphorylated tau proteins,and ameliorates memory defects and neuronal damage in 3×Tg-AD transgenic mice.Our studies demonstrate a promising strategy to restore autophagic flux and improve neuronal proteostasis by rationally-engineered nano-systems for delaying the progression of AD.

Nanosize aminated fullerene for autophagic flux activation and G0/G1 phase arrest in cancer cells via post-transcriptional regulation

Functional fullerene derivatives exhibit special inhibitory effects on tumor progress and metastasis via diverse tumor microenvironment regulations,while the elusive molecular mechanisms hinder their clinical transformation.Herein,it is initially revealed that nanosize aminated fullerene(C_(70)-EDA)can activate autophagic flux,induce G0/G1 cell cycle arrest to abrogate cancer cell proliferation,and significantly inhibit tumor growth in vivo.Mechanismly,C_(70)-EDA promotes the expression of cathepsin D involved in autophagic activation via post-transcriptional regulation,attributing to the interaction with a panel of RNA binding proteins.The accumulation of cathepsin D induces the autophagic degradation of cyclin D1,which arouses G0/G1 phase arrest.This work unveils the fantastic anti-tumor activity of aminated fullerene,elucidates the molecular mechanism,and provides a new strategy for the antineoplastic drug development on functional fullerenes.

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.

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.

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.

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.

MicroRNA-34c-5p provokes isoprenaline-induced cardiac hypertrophy by modulating autophagy via targeting ATG4B

Pathological cardiac hypertrophy serves as a significant foundation for cardiac dysfunction and heart failure. Recently, growing evidence has revealed that microRNAs(miRNAs) play multiple roles in biological processes and participate in cardiovascular diseases. In the present research, we investigate the impact of miRNA-34 c-5 p on cardiac hypertrophy and the mechanism involved. The expression of miR-34 c-5 p was proved to be elevated in heart tissues from isoprenaline(ISO)-infused mice. ISO also promoted miR-34 c-5 p level in primary cultures of neonatal rat cardiomyocytes(NRCMs). Transfection with miR-34 c-5 p mimic enhanced cell surface area and expression levels of foetal-type genes atrial natriuretic factor(Anf) and β-myosin heavy chain(β-Mhc) in NRCMs. In contrast, treatment with miR-34 c-5 p inhibitor attenuated ISO-induced hypertrophic responses. Enforced expression of miR-34 c-5 p by tail intravenous injection of its agomir led to cardiac dysfunction and hypertrophy in mice, whereas inhibiting miR-34 c-5 p by specific antagomir could protect the animals against ISO-triggered hypertrophic abnormalities. Mechanistically, miR-34 c-5 p suppressed autophagic flux in cardiomyocytes, which contributed to the development of hypertrophy. Furthermore, the autophagy-related gene 4 B(ATG4 B) was identified as a direct target of miR-34 c-5 p, and miR-34 c-5 p was certified to interact with 3’untranslated region of Atg4 b mRNA by dual-luciferase reporter assay. miR-34 c-5 p reduced the expression of ATG4 B, thereby resulting in decreased autophagy activity and induction of hypertrophy. Inhibition of miR-34 c-5 p abolished the detrimental effects of ISO by restoring ATG4 B and increasing autophagy. In conclusion, our findings illuminate that miR-34 c-5 p participates in ISO-induced cardiac hypertrophy, at least partly through suppressing ATG4 B and autophagy. It suggests that regulation of miR-34 c-5 p may offer a new way for handling hypertrophy-related cardiac dysfunction.

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.