The interaction of Atg4B and Bcl-2 plays an important role in Cd-induced crosstalk between apoptosis and autophagy through disassociation of Bcl-2-Beclin1 in A549 cells

Cadmium toxicity and autophagy: a review

Cadmium (Cd) is an important environmental pollutant that poses a threat to human health and represents a critical component of air pollutants, food sources, and cigarette smoke. Cd is a known carcinogen and has toxic effects on the environment and various organs in humans. Heavy metals within an organism are difficult to biodegrade, and those that enter the respiratory tract are difficult to remove. Autophagy is a key mechanism for counteracting extracellular (microorganisms and foreign bodies) or intracellular (damaged organelles and proteins that cannot be degraded by the proteasome) stress and represents a self-protective mechanism for eukaryotes against heavy metal toxicity. Autophagy maintains cellular homeostasis by isolating and gathering information about foreign chemicals associated with other molecular events. However, autophagy may trigger cell death under certain pathological conditions, including cancer. Autophagy dysfunction is one of the main mechanisms underlying Cd-induced cytotoxicity. In this review, the toxic effects of Cd-induced autophagy on different human organ systems were evaluated, with a focus on hepatotoxicity, nephrotoxicity, respiratory toxicity, and neurotoxicity. This review also highlighted the classical molecular pathways of Cd-induced autophagy, including the ROS-dependent signaling pathways, endoplasmic reticulum (ER) stress pathway, Mammalian target of rapamycin (mTOR) pathway, Beclin-1 and Bcl-2 family, and recently identified molecules associated with Cd. Moreover, research directions for Cd toxicity regarding autophagic function were proposed. This review presents the latest theories to comprehensively reveal autophagy behavior in response to Cd toxicity and proposes novel potential autophagy-targeted prevention and treatment strategies for Cd toxicity and Cd-associated diseases in humans.

Enhancing endometrial receptivity: the roles of human chorionic gonadotropin in autophagy and apoptosis regulation in endometrial stromal cells

Inadequate endometrial receptivity often results in embryo implantation failure and miscarriage. Human chorionic gonadotropin (hCG) is a key signaling molecule secreted during early embryonic development, which regulates embryonic maternal interface signaling and promotes embryo implantation. This study aimed to examine the impact of hCG on endometrial receptivity and its underlying mechanisms. An exploratory study was designed, and endometrial samples were obtained from women diagnosed with simple tubal infertility or male factor infertile (n = 12) and recurrent implantation failure (RIF, n = 10). Using reverse transcription-quantitative PCR and western blotting, luteinizing hormone (LH)/hCG receptor (LHCGR) levels and autophagy were detected in the endometrial tissues. Subsequently, primary endometrial stromal cells (ESCs) were isolated from these control groups and treated with hCG to examine the presence of LHCGR and markers of endometrial receptivity (HOXA10, ITGB3, FOXO1, LIF, and L-selectin ligand) and autophagy-related factors (Beclin1, LC3, and P62). The findings revealed that the expressions of receptivity factors, LHCGR, and LC3 were reduced in the endometrial tissues of women with RIF compared with the control group, whereas the expression of P62 was elevated. The administration of hCG to ESCs specifically activated LHCGR, stimulating an increase in the endometrial production of HOXA10, ITGB3, FOXO1, LIF and L-selectin ligands. Furthermore, when ESCs were exposed to 0.1 IU/mL hCG for 72 h, the autophagy factors Beclin1 and LC3 increased within the cells and P62 decreased. Moreover, the apoptotic factor Bax increased and Bcl-2 declined. However, when small interfering RNA was used to knock down LHCGR, hCG was less capable of controlling endometrial receptivity and autophagy molecules in ESCs. In addition, hCG stimulation enhanced the phosphorylation of ERK1/2 and mTOR proteins. These results suggest that women with RIF exhibit lower levels of LHCGR and compromised autophagy function in their endometrial tissues. Thus, hCG/LHCGR could potentially improve endometrial receptivity by modulating autophagy and apoptosis.

Copper homeostasis and cuproptosis in mitochondria

Mitochondria serve as sites for energy production and are essential for regulating various forms of cell death induced by metal metabolism, targeted anticancer drugs, radiotherapy and immunotherapy. Cuproptosis is an autonomous form of cell death that depends on copper (Cu) and mitochondrial metabolism. Although the recent discovery of cuproptosis highlights the significance of Cu and mitochondria, there is still a lack of biological evidence and experimental verification for the underlying mechanism. We provide an overview of how Cu and cuproptosis affect mitochondrial morphology and function. Through comparison with ferroptosis, similarities and differences in mitochondrial metabolism between cuproptosis and ferroptosis have been identified. These findings provide implications for further exploration of cuproptotic mechanisms. Furthermore, we explore the correlation between cuproptosis and immunotherapy or radiosensitivity. Ultimately, we emphasize the therapeutic potential of targeting cuproptosis as a novel approach for disease treatment.

The Role of Bcl-2 and Beclin-1 Complex in "Switching" between Apoptosis and Autophagy in Human Glioma Cells upon LY294002 and Sorafenib Treatment

BACKGROUND

Gliomas are the most malignant tumors of the central nervous system. One of the factors in their high drug resistance is avoiding programmed death (PCD) induction. This is related to the overexpression of intracellular survival pathways: PI3K-Akt/PKB-mTOR and Ras-Raf-MEK-ERK. Apoptosis and autophagy are co-existing processes due to the interactions between Bcl-2 and beclin-1 proteins. Their complex may be a molecular "toggle-switch" between PCD types. The aim of this research was to investigate the role of Bcl-2:beclin-1 complex in glioma cell elimination through the combined action of LY294002 and sorafenib.

METHODS

Drug cytotoxicity was estimated with an MTT test. The type of cell death was evaluated using variant microscopy techniques (fluorochrome staining, immunocytochemistry, and transmission electron microscopy), as well as the Bcl-2:beclin-1 complex formation and protein localization. Molecular analysis of PCD indicators was conducted through immunoblotting, immunoprecipitation, and ELISA testing. SiRNA was used to block Bcl-2 and beclin-1 expression.

RESULTS

The results showed the inhibitors used in simultaneous application resulted in Bcl-2:beclin-1 complex formation and apoptosis becoming dominant. This was accompanied by changes in the location of the tested proteins.

CONCLUSIONS

"Switching" between apoptosis and autophagy using PI3K and Raf inhibitors with Bcl-2:beclin-1 complex formation opens new therapeutic perspectives against gliomas.

Nephrotoxicity assessment of podophyllotoxin-induced rats by regulating PI3K/Akt/mTOR-Nrf2/HO1 pathway in view of toxicological evidence chain (TEC) concept

Adverse reactions to traditional Chinese medicine have hindered the healthy development and internationalization process of the traditional Chinese medicine industry. The critical issue that needs to be solved urgently is to evaluate the safety of traditional Chinese medicine systematically and effectively. Podophyllotoxin (PPT) is a highly active compound extracted from plants of the genus Podophyllum such as Dysosma versipellis (DV). However, its high toxicity and toxicity to multiple target organs affect the clinical application, such as the liver and kidney. Based on the concurrent effects of PPT's medicinal activity and toxicity, it would be a good example to conduct a systematic review of its safety. Therefore, this study revolves around the Toxicological Evidence Chain (TEC) concept. Based on PPT as the main toxic constituent in DV, observe the objective toxicity impairment phenotype of animals. Evaluate the serum biochemical indicators and pathological tissue sections for substantial toxic damage results. Using metabolomics, lipidomics, and network toxicology to evaluate the nephrotoxicity of PPT from multiple perspectives systematically. The results showed that PPT-induced nephrotoxicity manifested as renal tubular damage, mainly affecting metabolic pathways such as glycerophospholipid metabolism and sphingolipid metabolism. PPT inhibits the autophagy process of kidney cells through the PI3K/Akt/mTOR and Nrf2/HO1 pathways and induces the activation of oxidative stress in the body, thereby causing nephrotoxic injury. This study fully verified the feasibility of the TEC concept for the safety and toxicity evaluation of traditional Chinese medicine. Provide a research template for systematically evaluating the safety of traditional Chinese medicine.

Preclinical evaluation of Mito-LND, a targeting mitochondrial metabolism inhibitor, for glioblastoma treatment

BACKGROUND

Glioblastoma (GBM) is a brain tumor with the highest level of malignancy and the worst prognosis in the central nervous system. Mitochondrial metabolism plays a vital role in the occurrence and development of cancer, which provides critical substances to support tumor anabolism. Mito-LND is a novel small-molecule inhibitor that can selectively inhibit the energy metabolism of tumor cells. However, the therapeutic effect of Mito-LND on GBM remains unclear.

METHODS

The present study evaluated the inhibitory effect of Mito-LND on the growth of GBM cells and elucidated its potential mechanism.

RESULTS

The results showed that Mito-LND could inhibit the survival, proliferation and colony formation of GBM cells. Moreover, Mito-LND induced cell cycle arrest and apoptosis. Mechanistically, Mito-LND inhibited the activity of mitochondrial respiratory chain complex I and reduced mitochondrial membrane potential, thus promoting ROS generation. Importantly, Mito-LND could inhibit the malignant proliferation of GBM by blocking the Raf/MEK/ERK signaling pathway. In vivo experiments showed that Mito-LND inhibited the growth of GBM xenografts in mice and significantly prolonged the survival time of tumor-bearing mice.

CONCLUSION

Taken together, the current findings support that targeting mitochondrial metabolism may be as a potential and promising strategy for GBM therapy, which will lay the theoretical foundation for further clinical trials on Mito-LND in the future.

Autophagic Molecular Alterations in the Mouse Cerebellum Experimental Autoimmune Encephalomyelitis Model Following Treatment with Cannabidiol and Fluoxetine

The crosstalk between autophagy and apoptosis is one of the most important processes involved in the cell program death, and several mechanisms including oligodendrocyte apoptosis and autophagy play significant roles in activating macrophages, microglial cells, and finally demyelination in neurodegenerative disease. The antidepressants and anti-apoptotic mechanisms of fluoxetine (FLX) and cannabidiol (CBD) commence an autophagic event that can effectively repair myelin. This study aimed to investigate the effect of those reagents on the rate of demyelination in the cerebellum, an important site for white matter in a mouse model of experimental autoimmune encephalomyelitis (EAE). EAE was induced in twenty four adult female C57Bl/6 mice were inducted the EAE model; FLX treatment which was performed (10 mg/kg/IP) and CBD; were treated (5 mg/kg/IP); and their cerebellum was used for Western blotting, real-time PCR to autophagic markers of LC3II, Beclin-1, and apoptotic markers Bax and Bcl2 evaluation and Luxol Fast Blue staining to the assessment of demyelination. The level of autophagic markers was expressively elevated (P < 0.01) but the pro-apoptotic markers and Bax/Bcl2 ratio were reduced (P < 0.05). Luxol Fast Blue staining confirmed the noteworthy diminution of demyelination in treatment groups (P < 0.001). This finding clarified that FLX and CBD ameliorate the severity of the EAE model. Combinatory treatments of these two agents are suggested for future investigations.

Metformin attenuates symptoms of osteoarthritis: role of genetic diversity of Bcl2 and CXCL16 in OA

OBJECTIVE

This study aimed to evaluate the effectiveness of metformin versus placebo in overweight patients with knee osteoarthritis (OA). In addition, to assess the effects of inflammatory mediators and apoptotic proteins in the pathogenesis of OA, the genetic polymorphisms of two genes, one related to apoptosis (rs2279115 of Bcl-2) and the other related to inflammation (rs2277680 of CXCL-16), were investigated.

METHODS

In this double-blind placebo-controlled clinical trial, patients were randomly divided to two groups, one group receiving metformin (n = 44) and the other one receiving an identical inert placebo (n = 44) for 4 consecutive months (starting dose 0.5 g/day for the first week, increase to 1 g/day for the second week, and further increase to 1.5 g/day for the remaining period). Another group of healthy individuals (n = 92) with no history and diagnosis of OA were included in this study in order to evaluate the role of genetics in OA. The outcome of treatment regimen was evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. The frequency of variants of rs2277680 (A181V) and rs2279115 (938C>A) were determined in extracted DNAs using PCR-RFLP method.

RESULTS

Our results indicated an increase in scores of pain (P ≤ 0.0001), activity of daily living (ADL) (P ≤ 0.0001), sport and recreation (Sport/Rec) (P ≤ 0.0001), and quality of life (QOL) (P = 0.003) and total scores of the KOOS questionnaire in the metformin group compared to the placebo group. Susceptibility to OA was associated with age, gender, family history, CC genotype of 938C>A (Pa = 0.001; OR = 5.2; 95% CI = 2.0-13.7), and GG+GA genotypes of A181V (Pa = 0.04; OR = 2.1; 95% CI = 1.1-10.5). The C allele of 938C>A (Pa = 0.04; OR = 2.2; 95% CI = 1.1-9.8) and G allele of A181V (Pa = 0.02; OR = 2.2; 95% CI = 1.1-4.8) were also associated with OA.

CONCLUSION

Our findings support the possible beneficial effects of metformin on improving pain, ADL, Sport/Rec, and QOL in OA patients. Our findings support the association between the CC genotype of Bcl-2 and GG+GA genotypes of CXCL-16 and OA.

The protective mechanism of a novel polysaccharide from Lactobacillus-fermented Nostoc commune Vauch. on attenuating cadmium-induced kidney injury in mice

A novel polysaccharide (NCVP-F) from Lactobacillus-fermented Nostoc commune Vauch. was obtained to investigate its underlying mechanism in cadmium-induced kidney injury. Results indicated that in comparison with NCVP, NCVP-F with lower molecular weight of 365.369 kDa, exhibited higher mole percentage of Man and Glc-UA, whereas slightly lower mole percentage of other monosaccharides. NCVP-F is a α-pyran polysaccharide similar to NCVP. Meanwhile, NCVP-F can more effectively alleviate hepatorenal injury (ALT, AST, TG, BUN and SCr) and kidney tissue lesions in Cd-injured mice model by increasing antioxidant enzyme activity (SOD, GSH and GSH-Px), inhibiting cytokines levels (IL-6, IL-1β, TNF-α and IL-18). In addition, NCVP-F effectively inhibited apoptosis proteins (Bax, cytochrome c, a-caspase-9 and a-caspase-3) and enhanced anti-apoptotic protein (Bcl-2) probably via activating PI3K/AKT/mTOR pathway in the Cd-injury kidney. Furthermore, 16S rRNA sequencing results indicated that NCVP-F better enriched Lachnospiraceae, reduced Muribaculaceae, Alloprevotella and Blautia to regulate Cd-induced gut microbiota disorders, which was probably down-regulated 7 pathways including apoptosis and lipopolysaccharide biosynthesis, and up-regulated 63 pathways, such as carbohydrate metabolism and lipid metabolism. This study suggested that applying functional NCVP-F prepared by biotransformation with low molecular weight might be more beneficial.

Subacute Cadmium Exposure Induces Necroptosis in Swine Lung via Influencing Th1/Th2 Balance

Cadmium (Cd) is a type of toxic substance, which widely exists in nature. However, the effect of Cd exposure on the toxicity of swine lungs and its underlying mechanism involved have not yet been reported. In our study, we divided swine into two groups, including a control group (C group) and Cd-exposed group. Swine in the C group were fed a basic diet, whereas swine in the Cd group were fed a 20 mg Cd/kg diet. Immunofluorescence, qRT-PCR, western blot analysis, and H&E staining were performed to detect necroptosis-related indicators. Our results found that after Cd exposure, Th1/Th2 imbalance occurred, miR-181-5p was down-regulated, TNF-α expression was increased, and the NF-κB/NLRP3 and JAK/STAT pathways and RIPK1/RIPK3/MLKL axis were activated. Furthermore, histopathological examination showed necrosis in swine lung after Cd exposure. Together, the above-mentioned results indicate that subacute Cd exposure is closely linked with necroptosis in swine lung. Our study provided evidence that Cd may act through miR-181-5p/TNF-α to induce necroptosis in swine lung. The findings of this study supplement the toxicological study of Cd and provide a reference for comparative medicine.

The crosstalk among autophagy, apoptosis, and pyroptosis in cardiovascular disease

In recent years, the mechanism of cell death has become a hotspot in research on the pathogenesis and treatment of cardiovascular disease (CVD). Different cell death modes, including autophagy, apoptosis, and pyroptosis, are mosaic with each other and collaboratively regulate the process of CVD. This review summarizes the interaction and crosstalk of key pathways or proteins which play a critical role in the entire process of CVD and explores the specific mechanisms. Furthermore, this paper assesses the interrelationships among these three cell deaths and reviews how they regulate the pathogenesis of CVD. By understanding how these three cell death modes go together we can learn about the pathogenesis of CVD, which will enable us to identify new targets for preventing, controlling, and treating CVD. It will not only reduce mortality but also improve the quality of life.

Role of miR-451 in mediating cadmium induced head kidney injury in common carp via targeting cacna1ab through autophagy pathways

Cadmium (Cd) is a common environmental pollutant, which leads to Cd residue in aquatic animals. The Cd in aquatic animals will be enriched into the human body through the food chain and seriously harm human health. The research aims to investigate the molecular mechanism of Cd poisoning in common carps. Our previous studies have confirmed that 23 differentially expressed miRNAs were potential biomarkers for Cd exposure in common carp head kidney lymphocytes. Herein, based on the prediction of the website and previous studies, miR-451 and cacna1ab were selected and their targeting relationship was verified again by dual-luciferase. Subsequently, we established the miR-451 overexpression/knockdown models and miR-451 inhibitor, cacna1ab co-knockdown models in common carp head kidney lymphocytes respectively. Immunofluorescence staining, MDC staining, calcium staining, qRT-PCR (Quantitative Real-time PCR) and western blot were used to detect the levels of autophagy. Our results demonstrated that Cd significantly decreased the expression of miR-451, miR-451 suppression thereby induced increased cacna1ab and the expression of ATG5, LC3-I, LC3-II and Beclin 1, while significantly inhibiting the expression of mTOR, P62 and Bcl-2, which indicated that autophagy was triggered. Moreover, the miR-451 knockdown group activated the expression of autophagy related factors as well as the Cd group. However, cacna1ab knockdown can reduce autophagy activation induced by miR-451 knockdown. Our results indicated that Cd induced autophagy in head kidney lymphocytes through the inhibition of miR-451 and the excitation of cacna1ab.

ATF4/CEMIP/PKCα promotes anoikis resistance by enhancing protective autophagy in prostate cancer cells

The survival of cancer cells after detaching from the extracellular matrix (ECM) is essential for the metastatic cascade. The programmed cell death after detachment is known as anoikis, acting as a metastasis barrier. However, the most aggressive cancer cells escape anoikis and other cell death patterns to initiate the metastatic cascade. This study revealed the role of cell migration-inducing protein (CEMIP) in autophagy modulation and anoikis resistance during ECM detachment. CEMIP amplification during ECM detachment resulted in protective autophagy induction via a mechanism dependent on the dissociation of the B-cell lymphoma-2 (Bcl-2)/Beclin1 complex. Additional investigation revealed that acting transcription factor 4 (ATF4) triggered CEMIP transcription and enhanced protein kinase C alpha (PKCα) membrane translocation, which regulated the serine70 phosphorylation of Bcl-2, while the subsequent dissociation of the Bcl-2/Beclin1 complex led to autophagy. Therefore, CEMIP antagonization attenuated metastasis formation in vivo. In conclusion, inhibiting CEMIP-mediated protective autophagy may provide a therapeutic strategy for metastatic prostate cancer (PCa). This study delineates a novel role of CEMIP in anoikis resistance and provides new insight into seeking therapeutic strategies for metastatic PCa.

ATG 4B Serves a Crucial Role in RCE-4-Induced Inhibition of the Bcl-2-Beclin 1 Complex in Cervical Cancer Ca Ski Cells

RCE-4, a steroidal saponin isolated from Reineckia carnea, has been studied previously and has exhibited promising anti-cervical cancer properties by inducing programmed cell death (PCD) of Ca Ski cells. Considering the cancer cells developed various pathways to evade chemotherapy-induced PCD, there is, therefore, an urgent need to further explore the potential mechanisms underlying its actions. The present study focused on targeting the Bcl-2–Beclin 1 complex, which is known as the key regulator of PCD, to deeply elucidate the molecular mechanism of RCE-4 against cervical cancer. The effects of RCE-4 on the Bcl-2–Beclin 1 complex were investigated by using the co-immunoprecipitation assay. In addition, autophagy-related genes (ATG) were also analyzed due to their special roles in PCD. The results demonstrated that RCE-4 inhibited the formation of the Bcl-2–Beclin 1 complex in Ca Ski cells via various pathways, and ATG 4B proteins involved in this process served as a key co-factor. Furthermore, based on the above, the sensitivity of RCE-4 to Ca Ski cells was significantly enhanced by inhibiting the expression of the ATG 4B by applying the ATG 4B siRNA plasmid.

Metabolomics analysis reveals the effects of copper on mitochondria-mediated apoptosis in kidney of broiler chicken (Gallus gallus)

Copper (Cu) is one of the ubiquitous environmental pollutants which have raised wide concerns about the potential toxic effects and public health threat. For deeply investigating the nephrotoxicity induced by Cu, the effects of Cu on mitochondria-mediated apoptosis in kidney were first to analyze by combining metabolomics and molecular biology techniques. In this study, broiler chicks were fed with different contents of Cu (11, 110, 220, and 330 mg/kg Cu) for 49 d. The results of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining and transmission electron microscope showed that Cu could induce apoptosis in kidney, characterized by the increasing of TUNEL-positive cells and mitochondrial vacuolation. Additionally, a total of 62 differential metabolites were detected by liquid chromatography-mass spectrometry (LC-MS), and mainly enriched in the metabolic pathways including riboflavin metabolism, glutathione metabolism, sphingolipid metabolism, and glycerophospholipid metabolism, which were closely to mitochondrial metabolism. Meanwhile, the decreased mitochondrial membrane potential (MMP), increased mitochondrial membrane permeability and the change of mRNA and protein expression levels associated with mitochondria-mediated apoptosis and mitochondrial dynamics confirmed that Cu could induce mitochondria-mediated apoptosis. Therefore, our results demonstrated that Cu induced mitochondria-mediated apoptosis in kidney. Moreover, this study highlighted the metabolic characteristics of Cu to kidney, which suggested that mitochondrial metabolism could be considered as an important factor influencing toxicity.

miR-1 Targeted Downregulation of Bcl-2 Increases Chemosensitivity of Lung Cancer Cells

Objective: To investigate the expression of B cell lymphoma-2 (Bcl-2) in lung cancer cells and the effect of the miR-1/Bcl-2 axis on the chemosensitivity of lung cancer. Materials and Methods: Real-time quantitative PCR and western blotting were used to detect the expression of Bcl-2 in human embryonic lung fibroblasts and lung cancer cells. The effects of siRNA directed against Bcl-2, in lung cancer tissue samples was detected by immunohistochemistry; these results were used to develop prognostic models. Bioinformatic analyses, dual luciferase reporter gene technology, and western blotting technology were used to explore the targeted regulation of miR-1 on bcl-2. The effect of miR-1 on the chemosensitivity of lung cancer cells was measured using the MTT assay. Results: Compared with human embryonic lung fibroblasts, Bcl-2 was highly expressed in the lung cancer cells, especially in H460 cells. After silencing Bcl-2 with siRNA, the sensitivity of the cells to cisplatin (CDDP) increased. Immunohistochemical results and prognostic analysis revealed that high Bcl-2 expression in lung cancer tissues was negatively correlated with prognosis of lung cancer patients; A dual luciferase reporter assay combined with western blotting confirmed that miR-1 can bind to the Bcl-23' UTR region and regulate its expression. Overexpression of miR-1 in lung cancer cells (H460 and A549) increased the sensitivity of these cells to CDDP. Conclusion: Bcl-2 is upregulated in lung cancer cells, which is negatively correlated with the patient prognosis. miR-1 affects the chemosensitivity of lung cancer cells by targeting Bcl-2. These data should provide a theoretical basis for refining the molecular mechanisms of chemoresistance in lung cancer.

Exogenous spermine attenuates diabetic kidney injury in rats by inhibiting AMPK/mTOR signaling pathway

Diabetic nephropathy (DN) is the primary cause of end‑stage renal disease, which is closely associated with dysfunction of the podocytes, the main component of the glomerular filtration membrane; however, the exact underlying mechanism is unknown. Polyamines, including spermine, spermidine and putrescine, have antioxidant and anti‑aging properties that are involved in the progression of numerous diseases, but their role in DN has not yet been reported. The present study aimed to explore the role of polyamines in DN, particularly in podocyte injury, and to reveal the molecular mechanism underlying the protective effect of exogenous spermine. Streptozotocin intraperitoneal injection‑induced type 1 diabetic (T1D) rat models and high glucose (HG)‑stimulated podocyte injury models were established. It was found that in T1D rat kidneys and HG‑induced podocytes, ornithine decarboxylase (a key enzyme for polyamine synthesis) was downregulated, while spermidine/spermine N1‑acetyltransferase (a key enzyme for polyamines degradation) was upregulated, which suggested that reduction of the polyamine metabolic pool particularly decreased spermine content, is a major factor in DN progression. In addition, hyperglycemia can induce an increased rat kidney weight ratio, serum creatinine, urea, urinary albumin excretion and glomerular cell matrix levels, and promote mesangial thickening and loss or fusion of podocytes. The expression levels of podocyte marker proteins (nephrin, CD2‑associated protein and podocin) and autophagy‑related proteins [autophagy protein 5, microtube‑associated proteins 1A/1B light chain 3 (LC3)II/LC3I, Beclin 1 and phosphorylated (p)‑AMPK] were downregulated, while cleaved caspase‑3, P62 and p‑mTOR were increased. These changes could be improved by pretreatment with exogenous spermine or rapamycin (autophagic agonist). In conclusion, spermine may have the potential to prevent diabetic kidney injury in rats by promoting autophagy via regulating the AMPK/mTOR signaling pathway.

Sevoflurane-Induced Neuroapoptosis in Rat Dentate Gyrus Is Activated by Autophagy Through NF-κB Signaling on the Late-Stage Progenitor Granule Cells

Objective

The mechanisms by which exposure of the late-stage progenitor cells to the anesthesia sevoflurane alters their differentiation are not known. We seek to query whether the effects of sevoflurane on late-stage progenitor cells might be regulated by apoptosis and/or autophagy.

Methods

To address the short-term impact of sevoflurane exposure on granule cell differentiation, we used 5-bromo-2-deoxyuridine (BrdU) to identify the labeled late-stage progenitor granule cells. Male or female rats were exposed to 3% sevoflurane for 4 h when the labeled granule cells were 2 weeks old. Differentiation of the BrdU-labeled granule cells was quantified 4 and 7 days after exposure by double immunofluorescence. The expression of apoptosis and autophagy in hippocampal dentate gyrus (DG) was determined by western blot and immunofluorescence. Western blot for the expression of NF-κB was used to evaluate the mechanism. Morris water maze (MWM) test was performed to detect cognitive function in the rats on postnatal 28–33 days.

Results

Exposure to sevoflurane decreased the differentiation of the BrdU-labeled late-stage progenitor granule cells, but increased the expression of caspase-3, autophagy, and phosphorylated-P65 in the hippocampus of juvenile rats and resulted in cognitive deficiency. These damaging effects of sevoflurane could be mitigated by inhibitors of autophagy, apoptosis, and NF-κB. The increased apoptosis could be alleviated by pretreatment with the autophagy inhibitor 3-MA, and the increased autophagy and apoptosis could be reduced by pretreatment with NF-κB inhibitor BAY 11-7085.

Conclusion

These findings suggest that a single, prolonged sevoflurane exposure could impair the differentiation of late-stage progenitor granule cells in hippocampal DG and cause cognitive deficits possibly via apoptosis activated by autophagy through NF-κB signaling. Our results do not preclude the possibility that the affected differentiation and functional deficits may be caused by depletion of the progenitors pool.

The regulatory factors and pathological roles of autophagy-related protein 4 in diverse diseases: Recent research advances

Macroautophagy (autophagy) is an evolutionarily conserved and dynamic degradation/recycling pathway in which portions of the cytoplasm, such as dysfunctional proteins and surplus organelles, are engulfed by double-membrane bound vesicles through a lysosome-dependent process. As the only proteolytic enzyme of the core mammalian autophagy proteins, autophagy-related protein 4 (ATG4) primes newly synthesized pro-light chain 3 (LC3) to form LC3-I that attaches to phosphatidylethanolamine and delipidates LC3-PE to LC3-I for recycling. Besides autophagy, ATG4 has been shown to be involved in regulating various biological and pathological processes. The roles of ATG4 in cancer therapy, a methodology for ATG4 activity detection, and the discovery of chemical modulators have been well-reviewed. However, a comprehensive summary on how ATG4 is regulated by multiple factors and, thereby, how ATG4 influences autophagy or other pathways remains lacking. In this paper, we summarize multiple processes and molecules that regulate the activity of ATG4, such as micro-RNAs, posttranslational modifications, and small molecules. Additionally, we focus on the relationship between ATG4 and diverse diseases, including cancer, neurodegeneration, microbial infection, and other diseases. It provides insight regarding potential ATG4-targeted therapeutic opportunities, which could be beneficial for future studies and human health.

Metformin Mitigates Cartilage Degradation by Activating AMPK/SIRT1-Mediated Autophagy in a Mouse Osteoarthritis Model

Chondrocyte dysfunction is a key mechanism underlying osteoarthritis. Metformin has shown protective effects in many diseases. The present study aimed to investigate the effects of metformin on autophagy and apoptosis in the process of osteoarthritis. A mouse osteoarthritis model was set up by surgically destabilizing medial meniscus in the knee. Intraarticular injection of metformin or vehicle was applied in the right knee for eight weeks. Mouse articular chondrocytes were isolated and passaged for in vitro experiments. Small interfering RNA (siRNA) transfection was used to silence target genes. Western blotting, immunohistochemistry, transmission electron microscopy were used. After eight weeks, metformin restored surgery-induced upregulation of MMP13 and downregulation of type II collagen in the joint cartilage. In cultured primary murine chondrocytes, IL-1β aggravated apoptosis and catabolic response in a dose-dependent manner. In the presence of IL-1β, metformin increased phosphorylated levels of AMPKα and upregulated SIRT1 protein expression, leading to an increase in autophagy as well as a decrease in catabolism and apoptosis. Inactivating AMPKα or inhibiting SIRT1 prevented the augmented autophagy in the presence of metformin. Silencing AMPKα2, but not AMPKα1, reduced SIRT1 expression and downregulated autophagy in cultured chondrocytes. Metformin protects against IL-1β-induced extracellular matrix (ECM) degradation in cultured chondrocytes and in mouse osteoarthritis model through activating AMPKα/SIRT1 signaling. Metformin shed light on the treatment of osteoarthritis.

Autophagy-Related Beclin 1 and Head and Neck Cancers

Beclin 1, a positive regulator of autophagy, behaves as a double-edged sword in tumorigenesis. Beclin 1 contributes to tumor suppression by removing defective or damaged organelles and other cellular components; however, its activity can also stimulate cancer initiation and progression. In head and neck cancer, Beclin 1 overexpression promotes autophagy, which limits DNA damage and chromosomal instability and increases necrosis and inflammation by impacting apoptotic and autophagic pathways. This paper reviews the relationship between Beclin 1, carcinogenesis and head and neck cancer prognosis.

Astilbin protects chicken peripheral blood lymphocytes from cadmium-induced necroptosis via oxidative stress and the PI3K/Akt pathway

Astilbin (ASB), a dihydroflavonol glycoside, is widely found in a variety of plants and in functional foods and acts as a powerful antioxidant. The aim of this study was to investigate the underlying mechanisms involved in the antagonistic effects of ASB on cadmium (Cd)-induced necroptosis in chicken peripheral blood lymphocytes. Peripheral blood lymphocytes were aseptically collected from Roman white hens and then randomly divided into five groups: the control group was incubated without additional reagents, while the other groups were incubated with Cd, ASB, a combination of Cd and ASB, and 0.1% DMSO. After a 24 h treatment, cell samples were collected. The results showed that some morphological changes consistent with necroptosis were observed in the Cd-treated groups, suggesting the occurrence of necroptosis. Simultaneously, antioxidant activity markers (CAT, SOD, GSH, GSH-px, and T-AOC) decreased and indicators of oxidative stress (MDA, iNOS, NO, H₂O₂, ·OH and ROS) increased. The production of ROS induced the activation of the PI3K/Akt signaling pathway, as the expression levels of PI3K, Akt and PDK1 were significantly elevated. Additionally, the expression levels of RIPK3, RIPK1, MLKL, TAK1, TAB2 and TAB3 were increased and that of Caspase-8 was decreased, which could cause the necroptosis. However, the most important our results was that ASB supplements remarkably attenuated the Cd-induced effects. We conclude that the Cd treatment promoted an imbalance of the antioxidant status and activated the PI3K/Akt pathway, leading to necroptosis in chicken peripheral blood lymphocytes, and that ASB was able to partially ameliorate the effect of Cd-induced necroptosis.

Meriolin1 induces cell cycle arrest, apoptosis, autophagy and targeting the Akt/MAPKs pathways in human neuroblastoma SH-SY5Y cells

OBJECTIVES

Meriolins, a kind of chemical hybrid between meridianins and variolins, have lately been determined as kinase inhibitors and reportedly have antitumour activity. However, there is currently no in-depth study for the action mechanism. This study aimed to elucidate the potentially antitumour action mechanism of Meriolin1 on human neuroblastoma (SH-SY5Y) cells.

METHODS

Firstly, cell viability was detected by MTT assay. Secondly, cell cycle, cell apoptosis, cell autophagy, reactive oxygen species and mitochondrial membrane potential (ΔΨm) were measured by flow cytometry. Then, cell cycle-associated proteins, Bcl-2 family proteins, Akt/MAPK proteins and autophagy-associated proteins expressions were evaluated by Western blot. Bcl-2 and Bax mRNA expressions were also evaluated by qRT-PCR. Furthermore, cell adhesion assay and Hoechst 33258 fluorescent staining were carried out to detect the effect of Meriolin1 on cell adhesion and morphology. Finally, to gain further insight into mechanism of action of Meriolin1 to CDK protein, the molecular docking study was performed by using the CDOCKER module of DS software.

KEY FINDINGS

Meriolin1 could exert the antitumour activity on SH-SY5Y cells by inducing cell cycle arrest, cell autophagy, the mitochondrion-dependent cell apoptosis and targeting the Akt/MAPKs signalling pathway.

CONCLUSIONS

Meriolin1 might be a promising therapeutic candidate for neuroblastoma.

Rhodiola crenulata root extract ameliorates fructose-induced hepatic steatosis in rats: Association with activating autophagy

BACKGROUND

Increasing evidence has shown the beneficial effects of Rhodiola species on metabolic disorders, but their mechanisms are not clear. Hepatic steatosis is closely related to metabolic disorders, we aim to investigate the therapeutic effects of Rhodiola crenulata root (RCR) on fructose-induced hepatic steatosis and explore the underlying mechanisms.

PURPOSE

To observe the effect of Rhodiola crenulata root extract (RCR) on fructose-induced hepatic steatosis in Sprague-Dawley (SD) rats and explore its possible mechanism.

METHODS

Male Sprague-Dawley rats were treated with liquid fructose in their drinking water over 18 weeks. The extract of RCR was co-administered (once daily by oral gavage) during the last 5 weeks. Liver lipid deposition and morphological changes were observed by Oil red O staining. Real-time fluorescence quantitative PCR, Western blot and immunoprecipitation were used to detect gene and protein expression in liver.

RESULTS

RCR (50 mg/kg) reversed liquid fructose-induced increase in hepatic triglyceride content in rats. Attenuation of the increased vacuolization and Oil Red O staining area was evident on histological examination of liver in RCR-treated rats. However, RCR treatment did not affect chow intake and body weight of rats. Although some genes of the pathways involved in DNL (ChREBP, SREBP-1c, FAS, ACC1, SCD1, DGAT1, DGAT2 and MGAT2), fatty acid β-oxidation (PPARα, CPT1a, ACO and FGF21), VLDL-export (MTTP) and decomposition (HSL, ATGL) in the liver of fructose-fed rats were not changed significantly after RCR administration, the decrease in PPARα and PGC-1α proteins was reversed by RCR. Notably, SIRT1 mRNA and protein expression increased significantly with RCR administration. Furthermore, RCR increased expression of ATG4B, Beclin1 and decreased expression of Bcl2-Beclin1 complex dramatically. Meanwhile, RCR decreased the acetylation of beclin1. Moreover, RCR increased expression of autophagosome markers including LC3B and ATG5-ATG12-ATG16L1, and decreased expression of autophagolysosome marker p62 in the livers of fructose-fed rats.

CONCLUSIONS

RCR has a certain improvement effect on fructose-induced hepatic steatosis, which is related to the activation of autophagy.

Arsenic trioxide or/and copper sulfate co-exposure induce glandular stomach of chicken injury via destruction of the mitochondrial dynamics and activation of apoptosis as well as autophagy

Arsenic and copper are naturally occurring element. Contamination from natural processes and anthropogenic activities can be discovered all over the world and their unique interactions with the environment lead to widespread toxicity. When the content was excessive, the organism would be hurt seriously. The glandular stomach is an important organ of the poultry gastrointestinal tract. This study was aimed to investigate the toxicity of arsenic trioxide or/and copper sulfate (As or/and Cu) on chicken glandular stomach. Seventy-two 1-day-old Hy-Line chickens were randomly divided into control (C) group, arsenic trioxide (As) group, copper sulfate (Cu) group and arsenic trioxide and copper sulfate (AsCu) group, and exposed to 30 mg/kg arsenic trioxide or/and 300 mg/kg copper sulphates for 12 weeks. The indicators of mitochondrial dynamics, apoptosis and autophagy were tested in the glandular stomach. The results showed that exposure to As or/and Cu caused mitochondrial dynamic imbalance. Additionally, the levels of pro-apoptosis and autophagy indicators were increased and the levels of anti-apoptosis indicators were decreased in the treatment groups. Beyond that, in the treatment groups, we could clearly see karyopyknosis and chromatin condensation were associated with increased apoptosis rate, as well as the disappearance of the nuclear membrane, the swelling of mitochondria and the accumulation of autophagosomes were involved in the death of cells. It was worth noting that the glandular stomach lesions were time-dependent, and the combination of As and Cu were worse than the As and Cu alone. Collectively, our results suggest that As or/and Cu aggravate mitochondrial dysfunction, apoptosis and autophagy in a time-dependent manner, and the combined toxicity of As and Cu was higher.

Activation of autophagy inhibits cadmium-triggered apoptosis in human placental trophoblasts and mouse placenta

Cadmium (Cd), a ubiquitous environmental pollutant, is known to impair placental development. However, the underlying mechanisms remain unclear. The present study used in vivo and in vitro models to investigate the effects of Cd on apoptosis and autophagy in placental trophoblasts and its mechanism. Pregnant mice were exposed to CdCl₂ (4.5 mg/kg) on gestational day (GD) 9. Human JEG-3 cells were exposed to CdCl₂ (0-40 μM) for different time points. Gestational Cd exposure obviously lowered the weight and diameter of mouse placentas. Number of TUNEL-positive cells was markedly elevated in Cd-administered mouse placentas and JEG-3 cells. Correspondingly, Cd significantly up-regulated cleaved caspase-3 protein level, a key indicator of apoptosis, in murine placentas and JEG-3 cells. Simultaneously, Cd also triggered autophagy, as determined by an elevation of LC3B-II and p62 protein, and accumulation of LC3-positive puncta, in placental trophoblasts. Chloroquine an autophagy inhibitor, obviously aggravated Cd-induced apoptosis in JEG-3 cells. By contrast, rapamycin, a specific autophagy inducer, significantly alleviated Cd-triggered apoptosis in JEG-3 cells. Mechanistically, autophagy inhibited Cd-induced apoptosis mainly via degrading caspase-9. Co-localizations of p62, a classical autophagic receptor, and caspase-9 were observed in Cd-stimulated human JEG-3 cells. Moreover, p62 siRNAs pretreatment markedly blocked the degradation of caspase 9 proteins via Cd-activated autophagy in JEG-3 cells. Collectively, our data suggest that activation of autophagy inhibits Cd-induced apoptosis via p62-mediated caspase-9 degradation in placental trophoblasts. These findings provide a new mechanistic insight into Cd-induced impairments of placental and fetal development.

Hexabromocyclododecanes promoted autophagy through the PI3K/Akt/mTOR pathway in L02 cells

As additive brominated flame retardants, hexabromocyclododecanes (HBCDs) are being widely used in diverse artificial materials and products, including thermal insulation building materials, housings of electronic equipment, and upholstery textiles. Toxicology studies have shown that HBCDs exposure are closely related to hepatotoxicity and liver diseases. The present study is designed to explore how HBCDs affect cell apoptosis and autophagy process in a human hepatocyte cell line (L02) and to reveal the underline molecular mechanisms. Firstly, HBCDs could elevate the apoptosis rate of L02 cells dose-dependently. Three apoptosis related proteins (apoptotic protease activating factor 1 (Apaf-1), cysteinyl aspartate specific proteinase 3 (caspase-3) and cysteinyl aspartate specific proteinase 9 (caspase-9)) were observed to be up-regulated using western blotting method. Autophagy process was also started by HBCDs in L02 cells as indicated by the increased expressions of LC3-phosphatidylethanolamine conjugate (LC3-II) and other autophagic protein markers (Beclin-1, autophagy related protein 3 (Atg3), autophagy related protein 5 (Atg5), autophagy related protein 7 (Atg7) and autophagy related protein 16L1(Atg16L1)). The results of the green fluorescent protein (GFP)-microtubule-associated protein 1 light chain 3 (LC3) intracellular localization and fluorescence intensity further evidenced the activation of autophagy in L02 cells after treated with HBCDs. In addition, phosphatidylinositide 3-kinases/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway was activated in L02 cells by HBCDs, suggested by the increased expressions of related proteins. The inhibitors of PI3K (LY294002), DNA-activated protein kinase catalytic subunit (DNA-PKcs) (NU7441), Akt (MK2206), and mTOR (KU0063794) could obviously reduce the autophagic proteins prompted by HBCDs. The fluorescence intensities of GFP-LC3 transfected L02 cells were also decreased significantly after the application of these inhibitors. These results indicated that PI3K/Akt/mTOR pathway was participated in regulating autophagy process promoted by HBCDs. In above, HBCDs could induce mitochondrial-dependent apoptosis and autophagy in L02 cells, which was modulated by PI3K/Akt/mTOR pathway.

LAPTM4B knockdown increases the radiosensitivity of EGFR-overexpressing radioresistant nasopharyngeal cancer cells by inhibiting autophagy

Purpose

Nasopharyngeal carcinoma (NPC) is a malignant tumor that commonly occurs in southern China and Southeast Asia. Radiation therapy is the main treatment for patients with NPC, and the radioresistance of NPC is an unresolved clinical problem. This study focuses on the mechanism of NPC radioresistance and explores therapeutic targets and research directions for increasing the radiosensitivity of radioresistant cells.

Methods

We used a gradient dose model to establish radioresistant strains of 6-10B and CNE-2 human NPC cells. Plate colony formation assays were used to verify the radioresistance of the cells. We evaluated the expression of epidermal growth factor receptor (EGFR), lysosome-associated transmembrane protein 4β (LAPTM4B), Beclin1 and the autophagy-related proteins p62, LC3I, and LC3II by Western blot and observed GFP-LC3 puncta by confocal microscopy. The interaction between proteins was verified by immunofluorescence and coimmunoprecipitation analyses. Flow cytometry was performed to detect differences related to the apoptosis of radioresistant strains.

Results

The EGFR and LAPTM4B expression levels and autophagic flux were higher in radioresistant cells than in nonradioresistant cells, suggesting that EGFR and LAPTM4B are associated with autophagy levels. We observed that EGFR and LAPTM4B interact and stabilize each other in endosomes by confocal microscopy. LAPTM4B knockdown decreased the survival fraction of radioresistant cells and increased apoptosis after exposure to radiation. Coimmunoprecipitation experiments demonstrated that LAPTM4B interacts with Beclin1, which in turn promotes the initiation of autophagy.

Conclusion

This study illustrates a relationship among EGFR, LAPTM4B and autophagy in radioresistant NPC cell lines. LAPTM4B interacts with EGFR and Beclin 1, which promotes autophagy. LAPTM4B knockdown decreases radioresistance by inhibiting autophagy. This study proposes a possible mechanism for NPC radioresistance and provides a new research direction and theoretical basis for addressing the radioresistance of NPC.