[Tetrahydropalmatine inhibiting mitophagy through ULK1/FUNDC1 pathway to alleviate hypoxia/reoxygenation injury in H9c2 cells].

This study explored the specific mechanism by which tetrahydropalmatine(THP) inhibited mitophagy through the UNC-51-like kinase 1(ULK1)/FUN14 domain containing 1(FUNDC1) pathway to reduce hypoxia/reoxygenation(H/R) injury in H9c2 cells. This study used H9c2 cells as the research object to construct a cardiomyocyte H/R injury model. First, a cell viability detection kit was used to detect cell viability, and a micro-method was used to detect lactate dehydrogenase(LDH) leakage to evaluate the protective effect of THP on H/R injury of H9c2 cells. In order to evaluate the protective effect of THP on mitochondria, the chemical fluorescence method was used to detect intracellular reactive oxygen species, intramitochondrial reactive oxygen species, mitochondrial membrane potential, and autophagosomes, and the luciferin method was used to detect intracellular adenosine 5'-triphosphate(ATP) content. Western blot was further used to detect the ratio of microtubule-associated protein 1 light chain 3(LC3) membrane type(LC3-Ⅱ) and slurry type(LC3-Ⅰ) and activated cleaved caspase-3 expression level. In addition, ULK1 expression level and its phosphorylation degree at Ser555 site, as well as the FUNDC1 expression level and its phosphorylation degree of Ser17 site were detected to explore its specific mechanism. The results showed that THP effectively reduced mitochondrial damage in H9c2 cells after H/R. THP protected mitochondria by reducing the level of reactive oxygen species in cells and mitochondria, increasing mitochondrial membrane potential, thereby increasing cellular ATP production, enhancing cellular activity, reducing cellular LDH leakage, and finally alleviating H/R damage in H9c2 cells. Further studies have found that THP could reduce the production of autophagosomes, reduce the LC3-Ⅱ/LC3-Ⅰ ratio, and lower the expression of the apoptosis-related protein, namely cleaved caspase-3, indicating that THP could reduce apoptosis by inhibiting autophagy. In-depth studies have found that THP could inhibit the activation of the ULK1/FUNDC1 pathway of mitophagy and the occurrence of mitophagy by reducing the phosphorylation degree of ULK1 at Ser555 and FUNDC1 at Ser17. The application of ULK1 agonist BL-918 reversely verified the effect of THP on reducing the phosphorylation of ULK1 and FUNDC1. In summary, THP inhibited mitophagy through the ULK1/FUNDC1 pathway to reduce H/R injury in H9c2 cells.

Shikonin suppresses rheumatoid arthritis by inducing apoptosis and autophagy via modulation of the AMPK/mTOR/ULK-1 signaling pathway.

BACKGROUND: The overproliferation of fibroblast-like synoviocytes (FLS) contributes to synovial hyperplasia, a pivotal pathological feature of rheumatoid arthritis (RA). Shikonin (SKN), the active compound from Lithospermum erythrorhizon, exerts anti-RA effects by diverse means. However, further research is needed to confirm SKN's in vitro and in vivo anti-proliferative functions and reveal the underlying specific molecular mechanisms. PURPOSE: This study revealed SKN's anti-proliferative effects by inducing both apoptosis and autophagic cell death in RA FLS and adjuvant-induced arthritis (AIA) rat synovium, with involvement of regulating the AMPK/mTOR/ULK-1 pathway. METHODS: SKN's influences on RA FLS were assessed for proliferation, apoptosis, and autophagy with immunofluorescence staining (Ki67, LC3B, P62), EdU incorporation assay, staining assays of Hoechst, Annexin V-FITC/PI, and JC-1, transmission electron microscopy, mCherry-GFP-LC3B puncta assay, and western blot. In AIA rats, SKN's anti-arthritic effects were assessed, and its impacts on synovial proliferation, apoptosis, and autophagy were studied using Ki67 immunohistochemistry, TUNEL, and western blot. The involvement of AMPK/mTOR/ULK-1 pathway was examined via western blot. RESULTS: SKN suppressed RA FLS proliferation with reduced cell viability and decreased Ki67-positive and EdU-positive cells. SKN promoted RA FLS apoptosis, as evidenced by apoptotic nuclear fragmentation, increased Annexin V-FITC/PI-stained cells, reduced mitochondrial potential, elevated Bax/Bcl-2 ratio, and increased cleaved-caspase 3 and cleaved-PARP protein levels. SKN also enhanced RA FLS autophagy, featuring increased LC3B, reduced P62, autophagosome formation, and activated autophagic flux. Autophagy inhibition by 3-MA attenuated SKN's anti-proliferative roles, implying that SKN-induced autophagy contributes to cell death. In vivo, SKN mitigated the severity of rat AIA while also reducing Ki67 expression, inducing apoptosis, and enhancing autophagy within AIA rat synovium. Mechanistically, SKN modulated the AMPK/mTOR/ULK-1 pathway in RA FLS and AIA rat synovium, as shown by elevated P-AMPK and P-ULK-1 expression and decreased P-mTOR expression. This regulation was supported by the reversal of SKN's in vitro and in vivo effects upon co-administration with the AMPK inhibitor compound C. CONCLUSION: SKN exerted in vitro and in vivo anti-proliferative properties by inducing apoptosis and autophagic cell death via modulating the AMPK/mTOR/ULK-1 pathway. Our study revealed novel molecular mechanisms underlying SKN's anti-RA effects.

Saponins of Panax japonicus ameliorates cardiac aging phenotype in aging rats by enhancing basal autophagy through AMPK/mTOR/ULK1 pathway.

Heart disease is a significant health concern for elderly individuals, with heart aging being the primary cause. Recent studies have shown that autophagy can play a protective role in preventing cardiac aging. Our previous research confirmed that Chikusetsu saponin IVa, a fundamental component of Saponins of Panax japonics (SPJ), can enhance basic autophagy levels in cardiomyocyte of isoproterenol induced cardiac fibrosis mice. However, it remains unclear whether SPJ possesses a protective effect on cardiac dysfunction during the natural aging process. Rats were randomly divided into four groups: adult control group (6 months old), aging group (24 months old), aging group treated with 10 mg/kg SPJ, and aging group treated with 30 mg/kg SPJ. The heart function, blood pressure, and heart mass index (HMI) were measured. Hematoxylin and eosin staining (H&E) and Wheat Germ Agglutinin (WGA) staining were used to observe the changes in morphology, while Masson staining was used to examine collagen deposition in the rat hearts and CD45 immunohistochemistry was conducted to examine the macrophage infiltration in heart tissues. TUNEL kit was used to detect apoptosis level of cardiomyocyte, and western blot was used to evaluate autophagy-related proteins as well as AMPK/mTOR/ULK1 pathway-related markers. SPJ treatment improved the cardiac function, reduced HMI, attenuated myocardial fiber disorder, inhibited inflammatory cell infiltration, and decreased collagen deposition and cardiomyocyte apoptosis in aging rats. Additionally, SPJ treatment decreased the expression of aging-related proteins and restored the expression of autophagy-related markers. SPJ activated autophagy through the activation of AMPK, which in turn increased the phosphorylation of ULK1(Ser555), while inhibited the phosphorylation of mTOR and ULK1(Ser757). Our study demonstrates that SPJ improves the cardiac function of aging rats by enhancing basal autophagy through the AMPK/mTOR/ULK1 pathway. These results offer a theoretical foundation and empirical evidence to support the clinical advancement of SPJ in enhancing age-related cardiac dysfunction.

Activation of ULK1 to trigger FUNDC1-mediated mitophagy in heart failure: Effect of Ginsenoside Rg3 intervention.

BACKGROUND: Although the development of therapies for heart failure (HF) continues apace, clinical outcomes are often far from ideal. Unc51-like-kinase 1 (ULK1)-mediated mitophagy prevents pathological cardiac remodeling and heart failure (HF). Molecularly ULK1-targeted agent to enhance mitophagy is scanty. HYPOTHESIS/PURPOSE: This study aimed to investigate whether Ginsenoside Rg3 (Rg3) can activate ULK1 to trigger FUNDC1-mediated mitophagy for protecting heart failure. METHODS: Molecular docking and surface plasmon resonance were used to detect the ULK1 binding behavior of Rg3. Established HF model in rats and transcriptome sequencing were used to evaluate the therapeutic effect and regulatory mechanism of Rg3. Loss-of-function approaches in vivo and in vitro were performed to determine the role of ULK1 in Rg3-elicited myocardial protection against HF. FUNDC1 recombinant plasmid of site mutation was applied to elucidate more in-depth mechanisms. RESULTS: Structurally, a good binding mode was unveiled between ULK1 and Rg3. In vivo, Rg3 improved cardiac dysfunction, adverse remodeling, and mitochondrial damage in HF rats. Furthermore, Rg3 promoted Ulk1-triggered mitophagy both in vivo and in vitro, manifested by the impetus of downstream Fundc1-Lc3 interaction. Of note, the protective effects conferred by Rg3 against mitophagy defects, pathological remodeling, and cardiac dysfunction were compromised by Ulk1 gene silencing both in vivo and in vitro. Mechanistically, Rg3 activated mitophagy by inducing ULK1-mediated phosphorylation of FUNDC1 at the Ser17 site, not the Ser13 site. CONCLUSION: Together these observations demonstrated that Rg3 acts as a ULK1 activator for the precise treatment of HF, which binds to ULK1 to activate FUNDC1-mediated mitophagy.

Qiangjing tablets ameliorate asthenozoospermia via mitochondrial ubiquitination and mitophagy mediated by LKB1/AMPK/ULK1 signaling.

CONTEXT: Therapeutic effects of Qiangjing tablets (QJT) on sperm vitality and asthenozoospermia (AZS) have been confirmed. However, the mechanism of action remains unclear. OBJECTIVE: This study investigates the effects of QJT on AZS and the underlying mechanism of action. MATERIALS AND METHODS: Sixty Sprague-Dawley rats were randomly divided into six groups: Control, ORN (ornidazole; 200 mg/kg), ORN + QJT-low (0.17 g/mL), ORN + QJT-middle (0.33 g/mL), ORN + QJT-high (0.67 g/mL), and ORN + QJT + Radicicol (0.67 g/mL QJT and 20 mg/kg radicicol) groups. Pathological evaluation and analysis of mitophagy were conducted by H&E staining and transmission electron microscopy, respectively. Reactive oxygen species were detected by flow cytometry. Protein expression was determined by Western blotting. RESULTS: QJT significantly improved ORN-treated sperm motility and kinematic parameters, as well as the pathological symptoms of testicular and epididymal tissues. In particular, QJT mitigated impaired mitochondrial morphology, and increased the PHB, Beclin-1, LC3-II protein, and ROS levels (p < 0.05), and reduced the protein expression levels of LC3-I and p62 (p < 0.05). Mechanistically, QJT antagonized the downregulation of SCF and Parkin protein levels (p < 0.05). Furthermore, QJT significantly increased the protein expressions levels of LKB1, AMPKα, p-AMPKα, ULK1 and p-ULK1 (p < 0.05). The ameliorative effect of QJT on pathological manifestations, mitochondrial morphology, and the expressions of mitophagy and mitochondrial ubiquitination-related proteins was counteracted by radicicol. DISCUSSION AND CONCLUSIONS: QJT improved AZS via mitochondrial ubiquitination and mitophagy mediated by the LKB1/AMPK/ULK1 signaling pathway. Our study provides a theoretical basis for the treatment of AZS and male infertility.

Alpinetin alleviates osteoporosis by promoting osteogenic differentiation in BMSCs by triggering autophagy via PKA/mTOR/ULK1 signaling.

Osteoporosis, a systemic bone disease that is characterized by a reduction in bone mass and destruction of bone microstructure, is becoming a serious problem worldwide. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into bone-forming osteoblasts, and play an important role in maintaining homeostasis of bone metabolism, thus being a potential therapeutic target for osteoporosis. Although the phytochemical alpinetin (APT) has been reported to possess a variety of pharmacological activities, it is still unclear whether APT can influence the osteogenic differentiation of on BMSCs and if it can improve osteoporosis. In this study, we found that APT treatment was able to enhance osteogenic differentiation levels of human BMSCs in vitro and mouse ones in vivo as revealed by multiple osteogenic markers including increased alkaline phosphatase activity and osteocalcin expression. Mechanistically, the protein kinase A (PKA)/mTOR/ULK1 signaling was involved in the action of APT to enhance the osteogenic differentiation of BMSCs. In addition, oral administration of APT significantly mitigated the bone loss in a dexamethasone-induced mouse model of osteoporosis through strengthening PKA signaling and autophagy. Altogether, these data demonstrate that APT promotes osteogenic differentiation in BMSCs by augmenting the PKA/mTOR/ULK1 autophagy signaling, highlighting its potential therapeutic application for treating osteoporotic diseases.

Thymoquinone attenuates hepatic lipid accumulation by inducing autophagy via AMPK/mTOR/ULK1-dependent pathway in nonalcoholic fatty liver disease.

Thymoquinone (TQ) has been proved to exert wide-ranging pharmacological activities, with anti-inflammatory, antioxidant, anticonvulsant, antimicrobial, anti-tumor, and antidiabetic properties. In this study, we investigated the beneficial effects of TQ on a high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) in C57BL/6 N mice in vivo and free fatty acid (FFA)-induced human hepatocellular carcinoma HepG2 cells in vitro. Further, the underlying mechanisms of TQ to promote hepatic autophagy were also discovered. Data showed that TQ caused (p < 0.01) body weight reduction, improved glucose homeostasis, alleviated hepatosteatosis, and decreased hepatic lipid accumulation related to the induction of autophagy in HFD-fed mice. In vitro, TQ obviously increased (p < 0.01) autophagic flux in FFA-induced HepG2 cells and consequently reduced the lipid accumulation in combination with activation of AMPK/mTOR/ULK1 signaling pathways. Moreover, pharmacological inhibition of the AMPK pathway by addition with AMPK inhibitor Compound C (CC) or silence of ULK1 by transfection with siRNA(ULK1) into HepG2 cells reversed these beneficial effects of TQ on triggering hepatic autophagy and reducing lipid accumulation (p < 0.01). Taken together, these results suggested that TQ alleviated hepatic lipid accumulation by triggering autophagy through the AMPK/mTOR/ULK1-dependent signaling pathway. Our study supports a potential role for TQ in ameliorating NAFLD.

[Effect of moxibustion on AMPK/ULK1 signaling pathway in synovium tissue of toes in rats with rheumatoid arthritis].

OBJECTIVE: To observe the effect of moxibustion on AMP-activated protein kinase (AMPK)/UNC-51-like kinase 1 (ULK1) signaling pathway in the synovial tissue of toes in rheumatoid arthritis rats, so as to explore the mechanism of mo-xibustion in the treatment of rheumatoid arthritis (RA). METHODS: A total of 45 SD rats were randomly divided into blank, model， moxibustion, methotrexate and rapamycin groups, with 9 rats in each group. RA rat model was established by injection of Freund's complete adjuvant. Moxibustion was applied to "Zusanli" (ST36) and "Guanyuan" (CV4) for 20 min, once a day for 3 weeks. Methotrexate group was given methotrexate (0.35 mg/kg) by gavage, twice a week for 3 weeks. Rapamycin group was intraperitoneally injected with rapamycin (1 mg/kg)，once every other day for 3 weeks. The toe volume of the left hind limb of rats was measured by the toe volume measuring instrument. The content of AMP in toe synovium was detected by ELISA. The expression of AMPK and VPS34 protein in toe synovium was detected by Western blot.The expression of ULK1 and Atg13 mRNA in toe synovium was detected by RT-PCR. RESULTS: Compared with the blank group, the volume of toe in the model group was increased (P<0.01)，while the content of AMP, the expression of AMPK and VPS34 proteins, the expression of ULK1 and Atg13 mRNAs were significantly decreased(P<0.01).Compared with the model group, the volume of toe in the moxibustion，methotre-xate and rapamycin groups was decreased (P<0.05); the content of AMP, the expression of AMPK and VPS34 proteins, the expression of ULK1 and Atg13 mRNAs were significantly increased(P<0.05) in the moxibustion group; the content of AMP, the expression of VPS34 protein, the expression of Atg13 mRNA were significantly increased(P<0.05) in the methotrexate group; the expression of AMPK and VPS34 proteins, the expression of ULK1 and Atg13 mRNAs were significantly increased (P<0.05, P<0.01) in the rapamycin group. Compared with the moxibustion group, the expression of AMPK protein in the methotrexate group and the content of AMP in the rapamycin group were significantly decreased (P<0.05). CONCLUSION: Moxibustion can improve joint swelling in RA rats, and the mechanism may be related to promoting the activity of AMPK/ULK1 signaling pathway.

Osthole Suppresses Knee Osteoarthritis Development by Enhancing Autophagy Activated via the AMPK/ULK1 Pathway.

Knee osteoarthritis (KOA) is an increasingly prevalent heterogeneous disease characterized by cartilage erosion and inflammation. As the main chemical constituent of Angelicae Pubescentis Radix (APR), an anti-inflammatory herbal medicine, the potential biological effects and underlying mechanism of osthole on chondrocytes and KOA progression remain elusive. In this study, the potential effect and mechanism of osthole on KOA were investigated in vitro and in vivo. We found that osthole inhibited IL-1ß-induced apoptosis and cartilage matrix degeneration by activating autophagy in rat chondrocytes. In addition, osthole could activate autophagy through phosphorylation of AMPK/ULK1, and AMPK serves as a positive upstream regulator of ULK1. Furthermore, KOA rats treated with osthole showed phosphorylation of the AMPK/ULK1 pathway and autophagy activation, as well as cartilage protection. Collectively, the AMPK/ULK1 signaling pathway can be activated by osthole to enhance autophagy, thereby suppressing KOA development. Osthole may be a novel and effective therapeutic agent for the clinical treatment of KOA.

Zanthoxylum armatum DC. extract induces liver injury via autophagy suppression and oxidative damage by activation of mTOR/ULK1 pathway.

Zanthoxylum armatum DC. (ZADC) has anti-inflammatory, antioxidative, and antibacterial effects. The cytotoxicity of methanol extract of Zanthoxylum armatum DC. (MZADC) has been reported for BRL 3 A cell lines. However, whether MZADC can induce liver damage in vivo remains unclear. Therefore, it is essential to explore whether ZADC causes liver injury and, if the results confirm hepatotoxicity, to further study the potential mechanisms for the in-vitro cytotoxicity of the BRL 3 A cell lines. In vivo, different doses (0.346, 0.519, and 1.038 g/kg/day) of MZADC treatment were given by intragastric administration among male Sprague Dawley rats for 28 days. Levels of serum alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP) in the high dose group increased. Steatosis and focal necrosis were found in liver cells in rats in the high dose group. In vitro, BRL 3 A cells were cultivated with MZADC at different concentrations (30, 50, and 70 µg/mL) for 24 h. The cell viability, the number of autophagosomes, and the expression levels of LC3 and Beclin-1 were on a decreasing trend. Besides, proportions of p-mTOR/mTOR and p-ULK1/ULK1 increased. Meanwhile, reactive oxygen species (ROS) accumulation and the content of malondialdehyde (MDA) were on the rise while the activity of superoxide dismutase (SOD) and the content of glutathione (GSH) was on the decline. This research suggests that MZADC may cause rats liver injury and inhibit autophagy in BRL 3 A cells by the mTOR/ULK1 pathway, and further induce intracellular oxidative damage.

Chelerythrine ameliorates rheumatoid arthritis by modulating the AMPK/mTOR/ULK-1 signaling pathway.

BACKGROUND: Rheumatoid arthritis (RA) is a long-term, progressive, and disabling autoimmune disease. It causes inflammation, swelling and pain in and around the joints and other body organs. Currently, no cure is available for RA. Clinical interventions can only relieve the condition, and at least 30% of RA patients do not respond to first­line therapy. This means that the development of more effective therapies against RA is urgently needed. OBJECTIVE: This study aimed to assess the anti-rheumatoid arthritis effect of chelerythrine (CLT) and explore its mechanism of action. METHODS: The cytotoxic effect of CLT on human rheumatoid arthritis fibroblast-like synoviocyte (HFLS-RA) cells and HFLS-normal cells were measured by MTT assay. The growth and migration of HFLS-RA cells were determined by colony-formation and wound-healing assay. The level of intracellular reactive oxygen species (ROS) was detected using the DCFH-DA reagent. Cell apoptosis was measured by flow cytometry, TUNEL staining, caspase 3 activity, as well as the activation of apoptosis related proteins. In addition, the levels of autophagy related markers such as LC3B and P62 were determined by immunocytochemistry and western blotting. Lastly, the anti-RA effect of CLT was evaluated in an Adjuvant-Induced Arthritis(AIA) rat model and the severity of arthritis was detected and quantified using macroscopic inspection and X­ray imaging. RESULTS: We discovered that treatment with CLT effectively inhibited the migration and colony-formation of the HFLS-RA cells and resulted in cell death. Moreover, CLT increased the intracellular level of ROS and the apoptotic rate of HFLS-RA by activating the AMPK/mTOR/ULK-1 signaling pathways. In vivo study showed CLT effectively ameliorated AIA in rats, protecting them from inflammation and bone damage. CONCLUSION: Our study shows CLT is an effective agent for ameliorating RA in vitro and in vivo by modulation of the AMPK/mTOR/ULK-1 signaling pathway. These findings indicate that CLT is a great potential candidate for development as a therapeutic agent for the prevention and treatment of RA.

[Effect of electroacupuncture on hepatocyte autophagy and oxidative stress in SAMP8 mice by regulating AMPK/mTOR/ULK1 signaling pathway].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on physical strength and expression levels of hepatic AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), unc-51 like autophagy activating kinase 1 (ULK1) proteins and Atg5, Atg7, Atg13, Beclin1 and ULK1 mRNAs in aging (senescence accelerated mouse/prone 8, SAMP8)mice, so as to exp lore its mechanism underlying delaying aging by activating AMPK/mTOR/ULK1 signaling pathway. METHODS: Twenty-four male SAMP8 mice were randomly divided into model group, rapamycin (autophagy inducer) group, EA group and EA+autophagy inhibitor (EA+inhibitor) group, with 6 mice in each group, and 6 homologous anti-rapid aging male (SAMR1) mice in the same age were used as the control group. Mice of the rapamycin group received intraperitoneal injection of rapamycin solution (2 mg·kg-1·d-1). EA (2 Hz, 1 mA) was applied to bilateral "Taichong"(LR3)and "Shenshu"(BL23) for 15 min each time. Mice of the EA+inhibitor group received intraperitoneal injection of mTOR inhibitor 3-methyladenine (1.5 mg·kg-1·d-1) before the EA intervention each time. The above-mentioned interventions were conducted 6 times a week for 2 consecutive weeks. Physical conditions of mice were assessed by exhaustive swimming tests. Histopathological changes of the liver were observed by H.E. staining. Western blot was used to detect the expression of AMPK, phosphorylated AMPK (p-AMPK), mTOR, phosphorylated mTOR (p-mTOR), ULK1 and phosphorylated ULK1 (p-ULk1) in the liver tissues. The expression levels of Atg5, Atg7, Atg13, Beclin1 and ULK1 (cellular autophagy-related genes) mRNAs in the liver were detected by quantitative real-time PCR. The immunoactivity (IA) of heme oxygenase 1 (HO-1) in the liver was detected by immunohistochemistry, and the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) of the liver were measured by hydroxylamine method for assessing the level of oxidative stress. RESULTS: Compared with the control group, the duration of exhaustive swimming, the expression levels of AMPK, p-AMPK, ULK1 and p-ULK1 proteins, and Atg5, Atg7, Atg13, Beclin1 and ULK1 mRNA, HO-1 IA and SOD activity were considerably down-regulated (P<0.01), while the expression levels of mTOR and p-mTOR and MDA content were significantly up-regulated (P<0.01) in the model group. In comparison with the model group, the duration of the exhausted swimming, the expression levels of AMPK, p-AMPK, ULK1 and p-ULK1 proteins, and Atg5, Atg7, Atg13, Beclin1 and ULK1 mRNAs, HO-1 IA and SOD activity were significantly up-regulated (P<0.01, P<0.05), whereas the expression levels of mTOR and p-mTOR proteins and MDA content were notably down-regulated (P<0.01, P<0.05) in the rapamycin, EA and EA+inhibitor groups. The improvement of the abovementioned indexes of EA+inhibitor group was not as good as rapamycin and EA groups (P<0.01), suggesting an elimination of the therapeutic effects after administration of 3-methyladenine. No significant differences were found between the rapamycin and EA groups in the abovementioned indexes (P>0.05) except p-mTOR and mTOR which were higher in the EA group (P<0.01). H.E. staining showed ambiguous boundary of the liver lobule, disordered arrangement of hepatocytes with a large amount of fat vacuoles at different size and deviation of nucleus, and lysis of some hepatocytes. These situations were relatively milder in the rapamycin and EA groups. CONCLUSION: EA may enhance physical strength and promote cellular autophagy in the liver of aging mice by regulating AMPK/mTOR/ULK1 signaling, thereby inhibiting excessive oxidative stress, and delaying aging process to some extent.

[Effect of needle knife on mTOR/Atg/ULK1/Beclin-1 axis and chondrocyte autophagy in rats with knee osteoarthritis].

OBJECTIVE: To observe the effect of needle knife on chondrocyte autophagy and expressions of autophagy-related protein and mammalian target of rapamycin (mTOR) in rats with knee osteoarthritis (KOA), and to explore the possible mechanism of needle knife for KOA. METHODS: A total of 42 SD rats were randomly divided into a normal group, a model group and a needle knife group, 14 rats in each group. Except for the normal group, the other two groups were injected with the mixture of papain and L-cysteine into the left hind knee joint to establish the KOA model. After modeling, the rats in the needle knife group were treated with needle knife at strip or nodule around the quadriceps femoris and medial and lateral collateral ligament on the affected side, once a week for 3 times (3 weeks). The changes of left knee circumference in each group were observed; the chondrocytes and ultrastructure of left knee joint were observed by HE staining and electron microscope; the mRNA and protein expressions of autophagy-related genes (Atg5, Atg12, Atg4a), Unc-51 like autophagy activated kinase 1 (ULK1), autophagy gene Beclin-1 and mTOR in left knee cartilage were detected by real-time fluorescence quantitative PCR and Western blot. RESULTS: After modeling, the left knee circumferences in the model group and the needle knife group were increased compared with those before modeling and in the normal group (P<0.05); after intervention, the left knee circumference in the needle knife group was smaller than that in the model group and after modeling (P<0.05). Compared with the normal group, the number of chondrocytes was decreased, and a few cells swelled, nuclei shrank, mitochondria swelled and autophagosomes decreased in the model group; compared with the model group, the number of chondrocytes was increased , and most cell structures returned to normal, and autophagosomes was increased. Compared with the normal group, the mRNA and protein expressions of Atg5, Atg12, Atg4a, Beclin-1 and ULK1 in the knee cartilage in the model group were decreased (P<0.05); compared with the model group, the expressions of the above indexes in the needle knife group were increased (P<0.05). Compared with the normal group, the mRNA and protein expressions of mTOR in the knee cartilage in the model group were increased (P<0.05); compared with the model group, the expressions of the above indexes in the needle knife group were decreased (P<0.05). CONCLUSION: The needle knife intervention could improve knee cartilage injury in rats with KOA, and its mechanism may be related to reducing the expression of mTOR and up-regulating the expressions of Atg5, Atg12, Atg4a, ULK1 and Beclin-1, so as to promote chondrocyte autophagy and delay the aging and degeneration of chondrocytes.

Aconitine induces autophagy via activating oxidative DNA damage-mediated AMPK/ULK1 signaling pathway in H9c2 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Aconitum species, with a medicinal history of 2000 years, was traditionally used in the treatment of rheumatism, arthritis, bruises, and pains. However, many studies have reported that Aconitum species can cause arrhythmia in experimental animals, resulting in myocardial fibrosis and cardiomyocyte damage. Cardiotoxicity is the main toxic effect of aconitine, but the detailed mechanism remains unclear. AIM OF THE STUDY: This study aimed to explore the effects and underlying mechanism of autophagy in H9c2 cardiomyocytes induced by aconitine. MATERIALS AND METHODS: H9c2 cells were incubated with different concentrations of aconitine for 24 h, and the intervention sections were pretreated with various inhibitors for 1 h. The effects of aconitine on the oxidative DNA damage, autophagy and viability of H9c2 cells were evaluated by flow cytometry, confocal microscopy, enzyme-linked immunosorbent assay and Western blot. RESULTS: In H9c2 cells, the cell viability declined, LDH release rate, the number of autophagosomes, protein expression levels of LC3 and Beclin-1 increased significantly after 24 h of aconitine incubation. The pretreatment of autophagy inhibitor 3-MA decreased markedly autophagosomes and protein expression levels of LC3 and Beclin-1, which suggested that aconitine could induce cell autophagy. The significant increase of ROS and 8-OHdG showed that aconitine could cause oxidative DNA damage through ROS accumulation. Meanwhile, treatment of aconitine dramatically increased AMPKThr172 and ULK1Ser317 phosphorylation, and Compound C inhibited AMPKThr172 and ULK1Ser317 phosphorylation, which proved that aconitine induced autophagy via AMPK activation mediated ULK1 phosphorylation. Antioxidant NAC significantly reduced LDH, ROS and 8-OHdG, inhibited the phosphorylation of AMPKThr172 and ULK1Ser317, and down-regulated autophagosomes and proteins expression levels of LC3 and Beclin-1. Consequently, the inhibition of oxidative DNA damage and AMPK/ULK1 signaling pathway alleviated the aconitine-induced autophagic death of H9c2 cells. CONCLUSIONS: These results showed that aconitine induces autophagy of H9c2 cardiomyocytes by activating AMPK/ULK1 signaling pathway mediated by oxidative DNA damage. The autophagy induced by aconitine in cardiomyocytes is dependent on the activation of the AMPK pathway, which may provide novel insights into the prevention of aconitine-related toxicity.

Electroacupuncture Pretreatment Alleviates Cerebral Ischemia-Reperfusion Injury by Regulating Mitophagy via mTOR-ULK1/FUNDC1 Axis in Rats.

OBJECTIVE: Electroacupuncture (EA) pretreatment has been shown to alleviate cerebral ischemia-reperfusion (I/R) injury; however, the underlying mechanism remains unclear. To investigate the involvement of mTOR signaling in the protective role of EA in I/R-induced brain damage and mitochondrial injury. METHODS: Sprague-Dawley male rats were pretreated with vehicle, EA (at Baihui and Shuigou acupoints), or rapamycin + EA for 30 min daily for 5 consecutive days, followed by the middle cerebral artery occlusion to induce I/R injury. The neurological functions of the rats were assessed using the Longa neurological deficit scores. The rats were sacrificed immediately after neurological function assessment. The brains were obtained for the measurements of cerebral infarct area. The mitochondrial structural alterations were observed under transmission electron microscopy. The mitochondrial membrane potential changes were detected by JC-1 staining. The alterations in autophagy-related protein expression were examined using Western blot analysis. RESULTS: Compared with untreated I/R rats, EA-pretreated rats exhibited significantly decreased neurological deficit scores and cerebral infarct volumes. EA pretreatment also reversed I/R-induced mitochondrial structural abnormalities and loss of mitochondrial membrane potential. Furthermore, EA pretreatment downregulated the protein expression of LC3-II, p-ULK1, and FUNDC1 while upregulating the protein expression of p-mTORC1 and LC3-I. Rapamycin effectively blocked the above-mentioned effects of EA. CONCLUSION: EA pretreatment at Baihui and Shuigou alleviates cerebral I/R injury and mitochondrial impairment in rats through activating the mTORC1 signaling. The suppression of autophagy-related p-ULK1/FUNDC1 pathway is involved in the neuroprotective effects of EA.

Apigenin Induces Autophagy and Cell Death by Targeting EZH2 under Hypoxia Conditions in Gastric Cancer Cells.

Hypoxia is a major obstacle to gastric cancer (GC) therapy and leads to chemoresistance as GC cells are frequently exposed to the hypoxia environment. Apigenin, a flavonoid found in traditional medicine, fruits, and vegetables and an HDAC inhibitor, is a powerful anti-cancer agent against various cancer cell lines. However, detailed mechanisms involved in the treatment of GC using APG are not fully understood. In this study, we investigated the biological activity of and molecular mechanisms involved in APG-mediated treatment of GC under hypoxia. APG promoted autophagic cell death by increasing ATG5, LC3-II, and phosphorylation of AMPK and ULK1 and down-regulating p-mTOR and p62 in GC. Furthermore, our results show that APG induces autophagic cell death via the activation of the PERK signaling, indicating an endoplasmic reticulum (ER) stress response. The inhibition of ER stress suppressed APG-induced autophagy and conferred prolonged cell survival, indicating autophagic cell death. We further show that APG induces ER stress- and autophagy-related cell death through the inhibition of HIF-1α and Ezh2 under normoxia and hypoxia. Taken together, our findings indicate that APG activates autophagic cell death by inhibiting HIF-1α and Ezh2 under hypoxia conditions in GC cells.

Efficacy of Sijunzi decoction on limb weakness in spleen Qi deficiency model rats through adenosine monophosphate-activated protein kinase/unc-51 like autophagy activating kinase 1 signaling.

OBJECTIVE: To investigate the efficacy of Sijunzi decoction () on limb weakness in a rat model of spleen Qi deficiency (SQD), and to study its effect on mitophagy in skeletal muscle through adenosine monophosphate-activated protein kinase (AMPK) / unc-51 like autophagy activating kinase 1 (ULK1) signaling. METHODS: SQD model rats were produced by fasting combined with forced swimming method for 15 d. After model assessment, rats were randomly divided into four groups of 10 [low/middle/high (L/M/H) Sijunzi decoction dose groups and a normal saline (S) group]. Limb holding power (HP) and body mass (BM) were measured after 2 weeks of treatment. Following euthanasia, quadriceps femoris were dissected and myofiber and mitochondrial morphology were observed by transmission electron microscopy (TEM). Mitochondrial membrane potential (MMP), adenosine triphosphatase (ATP) and reactive oxygen species (ROS) levels were determined using colorimetric methods, and immunoblot analysis of Microtubule-associated protein light chain 3 (LC3) and Sequestosome 1 (p62) was performed to monitor mitophagy and AMPK/ULK1 signaling. RESULTS: Compared with control (C) group rats, in the S group, HP was reduced, the myofiber Z line was disordered, mitochondria were scattered, and numerous vacuoles and mitophagy were observed. MMP and ATP levels were reduced, ROS levels were elevated, and LC3B expression, and p-AMPKα (Thr172)/AMPKα, p-ULK1 (Ser555)/ULK1, and p-Raptor (Ser792)/Raptor ratios were increased, while p62 expression and p-mTOR (Ser2448)/mTOR and p-ULK1 (Ser757)/ULK1 ratios were decreased. After treatment, compared with the S group, HP was improved in M and H groups but not in the L group. Mitophagy was reduced in M, H and L groups but the Z line was disordered and vacuolization remained in the L group. ATP levels were elevated in M, H and L groups, and MMPs were elevat-ed in M and H groups but not in the L group. ROS levels were decreased in M, H and L groups, as were LC3B expression and p-Raptor (Ser792)/Raptor ratios, while p62 expression and p-mTOR (Ser2448)/mTOR and p-ULK1 (Ser757)/ULK1 ratios were increased in M and H groups but not in the L group. p-AMPKα (Thr172)/AMPKα and p-ULK1 (Ser555)/ULK1 ratios were decreased in M, H and L groups. CONCLUSIONS: Sijunzi decoction improved HP, possibly by inhibiting mitophagy via suppression of AMPK/ULK1 signaling. This restored mitochondrial morphology and improved oxidative phosphorylation, which contributed to recovery of limb weakness in SQD model rats.

Sex-Specific Differences in Autophagic Responses to Experimental Ischemic Stroke.

Ischemic stroke triggers a series of complex pathophysiological processes including autophagy. Differential activation of autophagy occurs in neurons derived from males versus females after stressors such as nutrient deprivation. Whether autophagy displays sexual dimorphism after ischemic stroke is unknown. We used a cerebral ischemia mouse model (middle cerebral artery occlusion, MCAO) to evaluate the effects of inhibiting autophagy in ischemic brain pathology. We observed that inhibiting autophagy reduced infarct volume in males and ovariectomized females. However, autophagy inhibition enhanced infarct size in females and in ovariectomized females supplemented with estrogen compared to control mice. We also observed that males had increased levels of Beclin1 and LC3 and decreased levels of pULK1 and p62 at 24 h, while females had decreased levels of Beclin1 and increased levels of ATG7. Furthermore, the levels of autophagy markers were increased under basal conditions and after oxygen and glucose deprivation in male neurons compared with female neurons in vitro. E2 supplementation significantly inhibited autophagy only in male neurons, and was beneficial for cell survival only in female neurons. This study shows that autophagy in the ischemic brain differs between the sexes, and that autophagy regulators have different effects in a sex-dependent manner in neurons.

V600EBRAF Inhibition Induces Cytoprotective Autophagy through AMPK in Thyroid Cancer Cells.

The dysregulation of autophagy is important in the development of many cancers, including thyroid cancer, where V600EBRAF is a main oncogene. Here, we analyse the effect of V600EBRAF inhibition on autophagy, the mechanisms involved in this regulation and the role of autophagy in cell survival of thyroid cancer cells. We reveal that the inhibition of V600EBRAF activity with its specific inhibitor PLX4720 or the depletion of its expression by siRNA induces autophagy in thyroid tumour cells. We show that V600EBRAF downregulation increases LKB1-AMPK signalling and decreases mTOR activity through a MEK/ERK-dependent mechanism. Moreover, we demonstrate that PLX4720 activates ULK1 and increases autophagy through the activation of the AMPK-ULK1 pathway, but not by the inhibition of mTOR. In addition, we find that autophagy blockade decreases cell viability and sensitize thyroid cancer cells to V600EBRAF inhibition by PLX4720 treatment. Finally, we generate a thyroid xenograft model to demonstrate that autophagy inhibition synergistically enhances the anti-proliferative and pro-apoptotic effects of V600EBRAF inhibition in vivo. Collectively, we uncover a new role of AMPK in mediating the induction of cytoprotective autophagy by V600EBRAF inhibition. In addition, these data establish a rationale for designing an integrated therapy targeting V600EBRAF and the LKB1-AMPK-ULK1-autophagy axis for the treatment of V600EBRAF-positive thyroid tumours.

Pien-Tze-Huang, a Chinese patent formula, attenuates NLRP3 inflammasome-related neuroinflammation by enhancing autophagy via the AMPK/mTOR/ULK1 signaling pathway.

NLRP3 inflammasome is a key mediator in ischemic stroke-induced neuroinflammation and subsequent brain injury. Our previous study demonstrated the potent activity of Pien-Tze-Huang (PTH), a well-known Chinese patent formula, in reducing mitochondria-mediated neuronal apoptosis in cerebral ischemia/reperfusion impaired rats. This study aims to elucidate the mechanistic action of PTH related to neuroinflammation in LPS-induced BV2 microglial cells and cerebral ischemia/reperfusion impaired rats. BV2 cells were stimulated with LPS for 12 h and treated with PTH with various concentrations. Modulation by PTH of relevant genes (IL-6, IL-1ß, IL-18, TNF-α, COX-2 and iNOS mRNA) and proteins (NLRP3 inflammasome, autophagy and AMPK/mTOR/ULK signaling) was analyzed by real-time PCR and western blot, respectively. Similar analyses were conducted in middle cerebral artery occlusion rat model including neurological deficit, infarct volume, microglial activation, and key genes and proteins in modulating autophagy and NLRP3. Our results showed that PTH significantly inhibited the production of key proinflammatory mediators and protein expressions of NLRP3 and caspase-1 p20 in LPS induced BV2 cells. It also enhanced the autophagy response by modulating the key autophagy proteins via AMPK/mTOR/ULK related pathway. The reduced inflammatory responses and NLRP3 expressions by PTH were partially blocked by the autophagy inhibitor (3-MA) and AMPK blocker (compound C). In rats, PTH significantly reduced infarct size, suppressed microglial activation, and improved neuron deficit. It also promoted autophagy and reduced NLRP3 activity. Our study demonstrated that PTH inhibited NLRP3 inflammasome-mediated neuroinflammation, which was associated with enhanced autophagy via AMPK/mTOR/ULK1 pathway in vitro and in vivo.