Effects of gamma-ray irradiation on material and electrical properties of AlN gate dielectric on 4H-SiC.

This article investigates the radiation effects on as-deposited and annealed AlN films on 4H-SiC substrates under gamma-rays. The AlN films are prepared using plasma-enhanced-atomic-layer-deposition on an n-type 4H-SiC substrate. The AlN/4H-SiC MIS structure is subjected to gamma-ray irradiation with total doses of 0, 300, and 600 krad(Si). Physical, chemical, and electrical methods were employed to study the variations in surface morphology, charge transport, and interfacial trapping characteristics induced by irradiation. After 300 krad(Si) irradiation, the as-deposited and annealed samples exhibit their highest root mean square values of 0.917 nm and 1.190 nm, respectively, which is attributed to N vacancy defects induced by irradiation. Under irradiation, the flatband voltage (Vfb) of the as-deposited sample shifts from 2.24 to 0.78 V, while the annealed sample shifts from 1.18 to 2.16 V. X-ray photoelectron spectrum analysis reveals the decomposition of O-related defects in the as-deposited AlN and the formation of Al(NOx)ycompounds in the annealed sample. Furthermore, the space-charge-limits-conduction (SCLC) in the as-deposited sample is enhanced after radiation, while the barrier height of the annealed sample decreases from 1.12 to 0.84 eV, accompanied by the occurrence of the SCLC. The physical mechanism of the degradation of electrical performance in irradiated devices is the introduction of defects like N vacancies and O-related defects like Al(NOx)y. These findings provide valuable insights for SiC power devices in space applications.

Recalled age of myopia onset may predict risk of high adult myopia in Chinese adults.

INTRODUCTION: This study aimed to investigate the relationship between age of myopia onset and high myopia and to explore if age of onset mediated the associations of high myopia with parental myopia and time spent on electronics. METHODS: This cross-sectional study enrolled 1118 myopic patients aged 18 to 40. Information was obtained via a detailed questionnaire. Multivariable logistic regression and linear regression models were utilized to assess age of onset in relation to high myopia and spherical equivalent refractive error, respectively. Structural equation models examined the mediated effect of onset age on the association between parental myopia, time spent on electronics and high myopia. RESULTS: An early age at myopia onset was negatively correlated with spherical equivalent refractive power. Subjects who developed myopia before the age of 12 were more likely to suffer from high myopia than those who developed myopia after the age of 15. Age of myopia onset was the strongest predictor of high myopia, with an area under the curve (AUC) in Receiver Operator Characteristic (ROC) analysis of 0.80. Additionally, age of myopia onset served as a mediator in the relationships between parental myopia, electronic device usage duration, and the onset of high myopia in adulthood. CONCLUSIONS: Age of myopia onset might be the single best predictor for high myopia, and age at onset appeared to mediate the associations of high myopia with parental myopia and time spent on electronics.

Identification of mitochondrial related signature associated with immune microenvironment in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most common neurodegenerative disease. Mitochondrial dysfunction and immune responses are important factors in the pathogenesis of AD, but their crosstalk in AD has not been studied. In this study, the independent role and interaction of mitochondria-related genes and immune cell infiltration in AD were investigated using bioinformatics methods. METHODS: The datasets of AD were obtained from NCBI Gene Expression Omnibus (GEO), and the data of mitochondrial genes was from MitoCarta3.0 database. Subsequently, differential expression genes (DEGs) screening and GSEA functional enrichment analysis were performed. The intersection of DEGs and mitochondrial related genes was used to obtain MitoDEGs. The MitoDEGs most relevant to AD were determined by Least absolute shrinkage and selection operator and multiple support vector machine recursive feature elimination, as well as protein-protein interactions (PPI) network and random forest. The infiltration of 28 kinds of immune cells in AD was analyzed by ssGSEA, and the relationship between hub MitoDEGs and the proportion of immune infiltration was studied. The expression levels of hub MitoDEGs were verified in cell models and AD mice, and the role of OPA1 in mitochondrial damage and neuronal apoptosis was investigated. RESULTS: The functions and pathways of DEGs were significantly enriched in AD, including immune response activation, IL1R pathway, mitochondrial metabolism, oxidative damage response and electron transport chain-oxphos system in mitochondria. Hub MitoDEGs closely related to AD were obtained based on PPI network, random forest and two machine learning algorithms. Five hub MitoDEGs associated with neurological disorders were identified by biological function examination. The hub MitoDEGs were found to be correlated with memory B cell, effector memory CD8 T cell, activated dendritic cell, natural killer T cell, type 17 T helper cell, Neutrophil, MDSC, plasmacytoid dendritic cell. These genes can also be used to predict the risk of AD and have good diagnostic efficacy. In addition, the mRNA expression levels of BDH1, TRAP1, OPA1, DLD in cell models and AD mice were consistent with the results of bioinformatics analysis, and expression levels of SPG7 showed a downward trend. Meanwhile, OPA1 overexpression alleviated mitochondrial damage and neuronal apoptosis induced by Aß1-42. CONCLUSIONS: Five potential hub MitoDEGs most associated with AD were identified. Their interaction with immune microenvironment may play a crucial role in the occurrence and prognosis of AD, which provides a new insight for studying the potential pathogenesis of AD and exploring new targets.

Hyperuricemia as an effect modifier of the association between metabolic phenotypes and nonalcoholic fatty liver disease in Chinese population.

BACKGROUND: Different metabolic phenotypes may be related to nonalcoholic fatty liver disease (NAFLD), but such association whether modified by serum uric acid levels is unknown. We examined the association between different metabolic phenotypes and NAFLD and further explore whether hyperuricemia could modify this association. METHODS: A total of 2959 participants (mean age: 55.02 years) with medical checkups were recruited from Tianjin Medical University General Hospital. Participants were categorized into four groups according to their BMI levels and metabolically healthy status: metabolically healthy normal weight (MHNW), metabolically healthy overweight or obese (MHO), metabolically unhealthy normal weight (MUNW), and metabolically unhealthy overweight or obese (MUO). Blood samples (including serum uric acid) were collected from participants after an overnight fast. NAFLD was diagnosed based on abdominal ultrasonography scanning. Data were analyzed using logistic regression models and the interaction effect model. RESULTS: The prevalence of NAFLD in MHNW, MHO, MUNW, and MUO groups was 9.9% (7.9-12.0%), 42.8% (39.5-46.1%), 36.5% (31.2-41.9%), and 69.7% (66.8-72.6%), respectively. In multi-adjusted logistic models, the ORs (95% CIs) of NAFLD were 5.32 (4.01-7.04) for participants with MHO, 4.51 (3.17-6.40) for those with MUNW, and 13.68 (10.23-18.30) for those with MUO compared to those with MHNW. In the stratified analysis by uric acid levels, the prevalence of NAFLD was significantly higher in participants with MHO, MUNW, and MUO in the hyperuricemia group than those in the normal uric acid group, and the interaction effect of metabolic phenotypes and uric acid on NAFLD was statistical significant (P < 0.05). CONCLUSIONS: MHO, MUNW, and MUO were associated with higher prevalence of NAFLD. Serum uric acid levels may modify the association between metabolically phenotypes and NAFLD.

Crosstalk between exosomes and autophagy: A review of molecular mechanisms and therapies.

Exosomes are extracellular vesicles that primarily exist in bodily fluids such as blood. Autophagy is an intracellular degradation process, which, along with exosomes, can significantly influence human health and has therefore attracted considerable attention in recent years. Exosomes have been shown to regulate the intracellular autophagic process, which, in turn, affects the circulating exosomes. However, crosstalk between exosomal and autophagic pathways is highly complex, depends primarily on the environment, and varies greatly in different diseases. In addition, studies have demonstrated that exosomes, from specific cell, can mitigate several diseases by regulating autophagy, which can also affect the excessive release of some harmful exosomes. This phenomenon lays a theoretical foundation for the improvement of many diseases. Herein, we review the mechanisms and clinical significance of the association and regulation of exosomes and autophagy, in order to provide a new perspective for the prevention and treatment of associated diseases.

The role of PD-L1 in the immune dysfunction that mediates hypoxia-induced multiple organ injury.

Hypoxia is a pathological condition common to many diseases, although multiple organ injuries induced by hypoxia are often overlooked. There is increasing evidence to suggest that the hypoxic environment may activate innate immune cells and suppress adaptive immunity, further stimulating inflammation and inhibiting immunosurveillance. We found that dysfunctional immune regulation may aggravate hypoxia-induced tissue damage and contribute to secondary injury. Among the diverse mechanisms of hypoxia-induced immune dysfunction identified to date, the role of programmed death-ligand 1 (PD-L1) has recently attracted much attention. Besides leading to tumour immune evasion, PD-L1 has also been found to participate in the progression of the immune dysfunction which mediates hypoxia-induced multiple organ injury. In this review, we aimed to summarise the role of immune dysfunction in hypoxia-induced multiple organ injury, the effects of hypoxia on the cellular expression of PD-L1, and the effects of upregulated PD-L1 expression on immune regulation. Furthermore, we summarise the latest information pertaining to the involvement, diagnostic value, and therapeutic potential of immunosuppression induced by PD-L1 in various types of hypoxia-related diseases, including cancers, ischemic stroke, acute kidney injury, and obstructive sleep apnoea. Video Abstract.

Self-Assembled Platinum Supramolecular Metallacycles Based on a Novel TADF Photosensitizer for Efficient Cancer Photochemotherapy.

Recently, supramolecular coordination complexes (SCCs) based on photosensitizers as bridging ligands have attracted great attention in cancer therapy owing to their synergistic effect between photodynamic therapy (PDT) and chemotherapy. Herein, a highly emissive supramolecular platinum triangle BTZPy-Pt based on a novel type of photosensitizer BTZPy with thermally activated delayed fluorescence (TADF) was fabricated. The BTZPy and BTZPy-Pt exhibited strong luminescence emission in the visible range with high quantum yields (quantum yields (QYs) for BTZPy and BTZPy-Pt were about 78 and 62% in ethanol solutions, respectively). Additionally, BTZPy had been proved to be an excellent photosensitizer with superior 1O2 generation capability (the 1O2 generation quantum yield reached up to ca. 95%) for PDT. By the combination of the excellent phototoxicity of BTZPy and the antitumor activity of the Pt center, the platinum triangle BTZPy-Pt demonstrated a highly efficient anticancer performance toward HeLa cells (IC50: 0.5 µg mL-1). This study not only provides a blueprint to fabricate new types of photosensitizers but also paves a way to design novel SCCs for efficient PDT.

G protein-coupled estrogen receptor 1 inhibits the epithelial-mesenchymal transition of goat mammary epithelial cells via NF-κB signalling pathway.

Mastitis is one of the most frequent clinical diseases in dairy animals. Epithelial cells undergoing epithelial-mesenchymal transition (EMT) promote the process of mastitis. Oestrogen deficiency is disadvantaged of many tissue inflammation and regeneration, while exogenous oestrogen treatment can reverse these effects. G protein-coupled estrogen receptor 1 (GPER1) is a membrane estrogen receptor. However, the potential effects of oestrogen via GPER1 on EMT in goat mammary epithelial cells (GMECs) are still unclear. Here, this study discovered that the activation of GPER1 by oestrogen could inhibit the EMT in GMECs via NF-κB signalling pathway. The activation of GPER1 by oestrogen inhibited the EMT accompanied by upregulation of E-cadherin and downregulation of N-cadherin and vimentin. Meanwhile, mRNA expression of transcription factors including Snail1 and ZEB1 was decreased. Further, like to oestrogen, GPER1 agonist G1 repressed the EMT progression. Conversely, GPER1 antagonist G15 reversed all these features induced by oestrogen. What's more, GPER1 silencing with shRNA promoted GMECs undergoing EMT. Additionally, oestrogen increased the phosphorylation of Erk1/2, which then decreased the phosphorylation and nuclear translocation of NF-κB, inhibiting the NF-κB signalling pathway activity. Taken, GPER1 may act as a suppressor through the regulation of EMT to prevent the development of mastitis.

Recent Development of Photothermal Agents (PTAs) Based on Small Organic Molecular Dyes.

Photothermal therapy (PTT) has attracted great attention due to its noninvasive and effective use against cancer. Various photothermal agents (PTAs) including organic and inorganic PTAs have been developed in the last decades. Organic PTAs based on small-molecule dyes exhibit great potential for future clinical applications considering their good biocompatibility and easy chemical modification or functionalization. In this review, we discuss the recent progress of organic PTAs based on small-molecule dyes for enhanced PTT. We summarize the strategies to improve the light penetration of PTAs, methods to enhance their photothermal conversion efficiency, how to optimize PTAs' delivery into deep tumors, and how to resist photobleaching under repeated laser irradiation. We hope that this review can rouse the interest of researchers in the field of PTAs based on small-molecule dyes and help them to fabricate next-generation PTAs for noninvasive cancer therapy.

The role of microvesicles containing microRNAs in vascular endothelial dysfunction.

Many studies have shown that endothelial dysfunction is associated with a variety of cardiovascular diseases. The endothelium is one of the primary targets of circulating microvesicles. Besides, microRNAs emerge as important regulators of endothelial cell function. As a delivery system of microRNAs, microvesicles play an active and important role in regulating vascular endothelial function. In recent years, some studies have shown that microvesicles containing microRNAs regulate the pathophysiological changes in vascular endothelium, such as cell apoptosis, proliferation, migration and inflammation. These studies have provided some clues for the possible roles of microvesicles and microRNAs in vascular endothelial dysfunction-associated diseases, and opened the door towards discovering potential novel therapeutic targets. In this review, we provide an overview of the main characteristics of microvesicles and microRNAs, summarizing their potential role and mechanism in endothelial dysfunction, and discussing the clinical application and existing problems of microvesicles for better translational applications.

The role of microvesicles and its active molecules in regulating cellular biology.

Cell-derived microvesicles are membrane vesicles produced by the outward budding of the plasma membrane and released by almost all types of cells. These have been considered as another mechanism of intercellular communication, because they carry active molecules, such as proteins, lipids and nucleic acids. Furthermore, these are present in circulating fluids, such as blood and urine, and are closely correlated to the progression of pathophysiological conditions in many diseases. Recent studies have revealed that microvesicles have a dual effect of damage and protection of receptor cells. However, the nature of the active molecules involved in this effect remains unclear. The present study mainly emphasized the mechanism of microvesicles and the active molecules mediating the different biological effects of receptor cells by affecting autophagy, apoptosis and inflammation pathways. The effective ways of blocking microvesicles and its active molecules in mediating cell damage when microvesicles exert harmful effects were also discussed.

Crosstalk of ER stress-mediated autophagy and ER-phagy: Involvement of UPR and the core autophagy machinery.

Endoplasmic reticulum (ER) stress, a common cellular stress response, is closely related to the activation of autophagy that is an important and evolutionarily conserved mechanism for maintaining cellular homeostasis. Autophagy induced by ER stress mainly includes the ER stress-mediated autophagy and ER-phagy. The ER stress-mediated autophagy is characterized by the generation of autophagosomes that include worn-out proteins, protein aggregates, and damaged organelles. While the autophagosomes of ER-phagy selectively include ER membranes, and the double membranes also derive, at least in part, from the ER. The signaling pathways of IRE1α, PERK, ATF6, and Ca2+ are necessary for the activation of ER stress-mediated autophagy, while the receptor-mediated selective ER-phagy degrades the ER is Atg40/FAM134B. The ER stress-mediated autophagy and ER-phagy not only have differences, but also have connections. The activation of ER-phagy requires the core autophagy machinery, and the ER-phagy may be a branch of ER stress-mediated autophagy that selectively targets the ER. However, the determined factors that control the changeover switch between ER stress-mediated autophagy and ER-phagy are largely obscure, which may be associated with the type of cells and the extent of stimulation. This review summarized the crosstalk between ER stress-mediated autophagy and ER-phagy and their signaling networks. Additionally, we discussed the possible factors that influence the type of autophagy induced by ER stress.

Intermittent-Hypoxia-Induced Autophagy Activation Through the ER-Stress-Related PERK/eIF2α/ATF4 Pathway is a Protective Response to Pancreatic ß-Cell Apoptosis.

BACKGROUND/AIMS: Intermittent hypoxia (IH) causes apoptosis in pancreatic ß-cells, but the potential mechanisms remain unclear. Endoplasmic reticulum (ER) stress, autophagy, and apoptosis are interlocked in an extensive crosstalk. Thus, this study aimed to investigate the contributions of ER stress and autophagy to IH-induced pancreatic ß-cell apoptosis. METHODS: We established animal and cell models of IH, and then inhibited autophagy and ER stress by pharmacology and small interfering RNA (siRNA) in INS-1 cells and rats. The levels of biomarkers for autophagy, ER stress, and apoptosis were evaluated by immunoblotting and immunofluorescence. The number of autophagic vacuoles was observed by transmission electron microscopy. RESULTS: IH induced autophagy activation both in vivo and in vitro, as evidenced by increased autophagic vacuole formation and LC3 turnover, and decreased SQSTM1 level. The levels of ER-stress-related proteins, including GRP78, CHOP, caspase 12, phosphorylated (p)-protein kinase RNA-like ER kinase (PERK), p-eIF2α, and activating transcription factor 4 (ATF4) were increased under IH conditions. Inhibition of ER stress with tauroursodeoxycholic acid or 4-phenylbutyrate partially blocked IH-induced autophagy in INS-1 cells. Furthermore, inhibition of PERK with GSK2606414 or siRNA blocked the ERstress-related PERK/eIF2α/ATF4 signaling pathway and inhibited autophagy induced by IH, which indicates that IH-induced autophagy activation is dependent on this signaling pathway. Promoting autophagy with rapamycin alleviated IH-induced apoptosis, whereas inhibition of autophagy with chloroquine or autophagy-related gene (Atg5 and Atg7) siRNA aggravated pancreatic ß-cell apoptosis caused by IH. CONCLUSION: IH induces autophagy activation through the ER-stress-related PERK/eIF2α/ATF4 signaling pathway, which is a protective response to pancreatic ß-cell apoptosis caused by IH.

Albumin Overload and PINK1/Parkin Signaling-Related Mitophagy in Renal Tubular Epithelial Cells.

BACKGROUND Albumin, as a major urinary protein component, is a risk factor for chronic kidney disease progression. Mitochondrial dysfunction is one of the main causes of albumin-induced proximal tubule cells injury. Mitophagy is considered as a pivotal protective mechanism for the elimination of dysfunctional mitochondria. The objective of this research was to determine whether albumin overload-induced mitochondrial dysfunction can activate PINK1/Parkin-mediated mitophagy in renal tubular epithelial cells (TECs). MATERIAL AND METHODS Immunofluorescence assay and Western blot assay were used to detect the effects of albumin overload on autophagy marker protein LC3. Transmission electron microscopy and Western blot assay were used to investigate the role of albumin in mitochondrial injury. Western blot assay and co-localization of acidic lysosomes and mitochondria assay were employed to detect the activation of mitophagy induced by albumin. Finally, we explored the role of PINK1/Parkin signaling in albumin-induced mitophagy by inhibiting mitophagy by knockdown of PARK2 (Parkin) level. RESULTS Immunofluorescence and Western blot results showed that the expression level of LC3-II increased, and the maximum increase point was observed after 8 h of albumin treatment. Transmission electron microscopy results demonstrated that albumin overload-induced mitochondrial injury and quantity of autophagosomes increased. Additionally, expression of PINK1 and cytosolic cytochrome C increased and mitochondria cytochrome C decreased in the albumin group. The co-localization of acidic lysosomes and mitochondria demonstrated that the number of albumin overload-induced mitophagy-positive dots increased. The transient transfection of PARK2 siRNA result showed knockdown of the expression level of PARK2 can inhibit mitophagy induced by albumin. CONCLUSIONS In conclusion, our study suggests that mitochondrial dysfunction activates the PINK1/Parkin signaling and mitophagy in renal tubular epithelial cells under albumin overload condition.

Effect of CPAP therapy on liver disease in patients with OSA: a review.

Obstructive sleep apnea (OSA) may play an important role in the progression of nonalcoholic fatty liver disease (NAFLD).The effect of continuous positive airway pressure (CPAP) treatment, the first-line therapy for OSA, on liver disease in OSA patients is still debated. We provide this review of previous studies to summarize the effects of CPAP treatment on liver disease in OSA patients in aspects of liver function, liver steatosis, fibrosis, and incidence of liver disease. CPAP treatment may be beneficial to liver disease in subjects with OSA independent of metabolic risk factors, but a sufficiently long therapeutic duration (perhaps greater than 3 months) may be needed to achieve these positive effects. Though the mechanism of impact of CPAP treatment on liver in OSA patients is unclear, the influence of CPAP treatment on the factors of the "Two-hit" hypothesis (insulin resistance, fatty acids dysregulation, oxidative stress, and inflammation) may be a reasonable explanation.

Crosstalk of autophagy and apoptosis: Involvement of the dual role of autophagy under ER stress.

Endoplasmic reticulum (ER) stress is a common cellular stress response that is triggered by a variety of conditions that disturb cellular homeostasis, and induces cell apoptosis. Autophagy, an important and evolutionarily conserved mechanism for maintaining cellular homeostasis, is closely related to the apoptosis induced by ER stress. There are common upstream signaling pathways between autophagy and apoptosis induced by ER stress, including PERK/ATF4, IRE1α, ATF6, and Ca2+ . Autophagy can not only block the induction of apoptosis by inhibiting the activation of apoptosis-associated caspase which could reduce cellular injury, but also help to induce apoptosis. In addition, the activation of apoptosis-related proteins can also inhibit autophagy by degrading autophagy-related proteins, such as Beclin-1, Atg4D, Atg3, and Atg5. Although the interactions of different autophagy- and apoptosis-related proteins, and also common upstream signaling pathways have been found, the potential regulatory mechanisms have not been clearly understood. In this review, we summarize the dual role of autophagy, and the interplay and potential regulatory mechanisms between autophagy and apoptosis under ER stress condition.

Sirt1: Role Under the Condition of Ischemia/Hypoxia.

Silent information regulator factor 2-related enzyme 1 (sirtuin 1, Sirt1) is a nicotinamide adenine dinucleotide-dependent deacetylase, which can deacetylate histone and non-histone proteins and other transcription factors, and is involved in the regulation of many physiological functions, including cell senescence, gene transcription, energy balance, and oxidative stress. Ischemia/hypoxia injury remains an unresolved and complicated situation in the diseases of ischemia stroke, heart failure, and coronary heart disease, especially among the old folks. Studies have demonstrated that aging could enhance the vulnerability of brain, heart, lung, liver, and kidney to ischemia/hypoxia injury and the susceptibility in old folks to ischemia/hypoxia injury might be associated with Sirt1. In this review, we mainly summarize the role of Sirt1 in modulating pathways against energy depletion and its involvement in oxidative stress, apoptosis, and inflammation under the condition of ischemia/hypoxia.

Effect of C-type natriuretic peptide on maturation and developmental competence of immature mouse oocytes in vitro.

In vitro maturation (IVM) of oocytes is an important assisted reproductive technology for infertility treatment and livestock breeding programs. Because of asynchronous nuclear and cytoplasmic maturation, the developmental competence of oocytes matured in vitro is compromised. C-Type natriuretic peptide (CNP), which has been proved to be an inhibitor of oocyte maturation, provides a new alternative to optimise synchronisation of nuclear and cytoplasmic maturation and improve developmental capacity of immature oocytes in vitro. To investigate the effect of temporary meiotic arrest mediated by CNP on maturation and subsequent development of immature oocytes, immature mouse oocytes from small antral follicles were temporarily arrested in meiosis by CNP (0, 5, 10 and 50nM) for 24h and then matured for 16h. CNP treatment significantly increased the oocyte maturation rate from less than half to above 80%. After IVF, temporary meiotic arrest mediated by 10 and 50nM CNP significantly improved fertilisation and blastocyst rate of oocytes matured in vitro up to approximately 55% and 30% respectively. Moreover, this positive effect of CNP was attributed, in part, to an increase in the number of mature oocytes with aligned chromosomes and a normal spindle. The present findings indicate the potential to use CNP to improve the efficiency of oocyte IVM.

Effect of different levels of intermittent hypoxia on autophagy of hippocampal neurons.

PURPOSE: The current study was carried out to assess the effects of different levels of intermittent hypoxia (IH) on autophagy in hippocampal neurons, and explore the extent, frequency and duration of IH for researching on autophagy in hippocampal neurons. METHODS: Hippocampal neurons were exposed to different levels of IH. To analyze the oxygen level of neuronal exposure environment, we detected the oxygen concentration in the chamber by O2 analyzer, and monitored the oxygen partial pressure (PO2), carbon dioxide partial pressure (PCO2), and pH in the culture media by blood gas analyzer. After 4-, 8-, and 12-h IH, the morphology and quantity of neurons, as well as the expression of light chain 3 (LC3)-II positive dots were observed by immunofluorescence. The expression of apoptosis marker protein cleaved caspase-3 and autophagy marker protein LC3 were examined by western blotting. RESULTS: The oxygen level in the chamber and the neuronal culture media both reached to the values set previously in three models. The level of cleaved caspase-3 and LC3 had no significant changes in IH-1 group. The morphology and quantity had no significant changes, while the levels of cleaved caspase-3 and LC3 were both increased in IH-2 group. The quantity of neurons was reduced significantly, and the chromatin condensed and nuclei fragmented in IH-3 group. CONCLUSIONS: The effects of varying degrees of IH on autophagy in hippocampal neurons are different. The IH model, hypoxia phase (1.5% O2, 5% CO2, and balance N2) for 5 min and reoxygenation phase (21% O2, 5% CO2, and balance N2) for 10 min, may be the best condition for researching on autophagy in hippocampal neurons.

The dual role of autophagy under hypoxia-involvement of interaction between autophagy and apoptosis.

Hypoxia is one of severe cellular stress and it is well known to be associated with a worse outcome since a lack of oxygen accelerates the induction of apoptosis. Autophagy, an important and evolutionarily conserved mechanism for maintaining cellular homeostasis, is closely related to the apoptosis caused by hypoxia. Generally autophagy blocks the induction of apoptosis and inhibits the activation of apoptosis-associated caspase which could reduce cellular injury. However, in special cases, autophagy or autophagy-relevant proteins may help to induce apoptosis, which could aggravate cell damage under hypoxia condition. In addition, the activation of apoptosis-related proteins-caspase can also degrade autophagy-related proteins, such as Atg3, Atg4, Beclin1 protein, inhibiting autophagy. Although the relationship between autophagy and apoptosis has been known for rather complex for more than a decade, the underlying regulatory mechanisms have not been clearly understood. This short review discusses and summarizes the dual role of autophagy and the interaction and molecular regulatory mechanisms between autophagy and apoptosis under hypoxia.