Low selenium and T-2 toxin may be involved in the pathogenesis of Kashin-Beck disease by affecting AMPK/mTOR/ULK1 pathway mediated autophagy.

Kashin-Beck disease (KBD) is an endemic, environmentally associated cartilage disease. Previous studies have shown that the environmental suspected pathogenic factors of KBD, T-2 toxin and low selenium, are involved in the regulation of inflammation, oxidative stress and autophagy in some tissues and organs. In cartilage diseases, the level of cellular autophagy determines the fate of the chondrocytes. However, whether autophagy is involved in KBD cartilage lesions, and the role of low selenium and T-2 toxins in KBD cartilage injury and autophagy are still unclear. This work took the classical AMPK/mTOR/ULK1 autophagy regulatory pathway as the entry point to clarify the relationship between the environmental suspected pathogenic factors and chondrocyte autophagy. Transmission electron microscopy was used to observe the autophagy of chondrocytes in KBD patients. qRT-PCR and western blot were used to analyze the expression of AMPK/mTOR/ULK1 pathway and autophagy markers. The rat model of KBD was established by low selenium and T-2 toxin, the autophagy in rat cartilage was detected after 4- and 12-week interventions. Chondrocyte autophagy was found in KBD, and the AMPK/mTOR/ULK1 pathway was down-regulated. In the rat model, the pathway showed an up-regulated trend when low selenium and T-2 toxin, were treated for a short time or low concentration, and autophagy level increased. However, when low selenium and T-2 toxin were treated for a long time or at high concentrations, the pathway showed a down-regulated trend, and the autophagy level was reduced and even defective. In conclusion, in the process of KBD cartilage lesion, chondrocyte autophagy level may increase in the early stage, and decrease in the late stage with the progression of lesion. Low selenium and T-2 toxins may affect autophagy by AMPK/mTOR/ULK1 pathway.

microRNA-125b-1-3p mediates autophagy via the RRAGD/mTOR/ULK1 signaling pathway and mitigates atherosclerosis progression.

Atherosclerosis is characterised by lipid accumulation and formation of foam cells in arterial walls. Dysregulated autophagy is a crucial factor in atherosclerosis development. The significance of microRNA (miR)-125b-1-3p in cardiovascular disease is well-established; however, its precise role in regulating autophagy and impact on atherosclerosis in vascular smooth muscle cells (VSMCs) remain unclear. Here, we observed reduced autophagic activity and decreased miR-125b expression during atherosclerosis progression. miR-125b-1-3p overexpression significantly reduced atherosclerotic plaque development in mice; it also led to decreased lipid uptake and deposition in VSMCs, enhanced autophagy, and suppression of smooth muscle cell phenotypic changes in-vitro. An interaction between miR-125b-1-3p and the RRAGD/mTOR/ULK1 pathway was revealed, elucidating its role in promoting autophagy. Therefore, miR-125b-1-3p plays a pivotal role in enhancing autophagic processes, inhibiting foam cell formation in VSMCs and mitigating atherosclerosis progression, partly through RRAGD/mTOR/ULK1 signaling axis modulation. Thus, miR-125b-1-3p is a promising target for preventive and therapeutic strategies for atherosclerosis.

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.

BNIP3-mediated autophagy via the mTOR/ULK1 pathway induces primordial follicle loss after ovarian tissue transplantation.

PURPOSE: To explore the underlying mechanism of primordial follicle loss in the early period following ovarian tissue transplantation (OTT). METHODS: BNIP3 was selected through bioinformatic protocols, as the hub gene related to autophagy during OTT. BNIP3 and autophagy in mice ovarian grafts and in hypoxia-mimicking KGN cells were detected using immunohistochemistry, transmission electron microscopy (TEM), western blotting, qPCR, and fluorescence staining. The regulatory role played by BNIP3 overexpression and the silencing of KGN cells in autophagy via the mTOR/ULK1 pathway was investigated. RESULTS: Ultrastructure examination showed that autophagic vacuoles increased after mice ovarian auto-transplantation. The BNIP3 and autophagy-related proteins (Beclin-1, LC3B, and SQSTM1/p62) in mice ovarian granulosa cells of primordial follicle from ovarian grafts were altered compared with the control. Administration of an autophagy inhibitor in mice decreased the depletion of primordial follicles. In vitro experiments indicated that BNIP3 and autophagy activity were upregulated in KGN cells treated with cobalt chloride (CoCl2). The overexpression of BNIP3 activated autophagy, whereas the silencing of BNIP3 suppressed it and reversed the autophagy induced by CoCl2 in KGN cells. Western blotting analysis showed the inhibition of mTOR and activation of ULK1 in KGN cells treated with CoCl2 and in the overexpression of BNIP3, and the opposite results following BNIP3 silencing. The activation of mTOR reversed the autophagy induced by BNIP3 overexpression. CONCLUSIONS: BNIP3-induced autophagy is crucial in primordial follicle loss during OTT procedure, and BNIP3 is a potential therapeutic target for primordial follicle loss after OTT.

Luteoloside pretreatment attenuates anoxia-induced damage in cardiomyocytes by regulating autophagy mediated by 14-3-3η and the AMPKα-mTOR/ULK1 pathway.

The relation between ischemia and heart failure is well demonstrated, and several studies suggested that realizing the physiological role of autophagy will be of great importance. Luteoloside (Lut) is one of the main components of Lonicera japonica flos and exhibits antioxidant, anti-inflammatory, and cardioprotective properties. To determine if Lut pretreatment enhanced autophagy by 14-3-3η expression and the AMPKα-mTOR/ULK1 pathway and protected the neonatal rat cardiomyocytes (NRCMs) against anoxia damage, NRCMs were treated using 20 µM Lut for 36 h, and the anoxia damage model was established using NRCMs. The indexes reflecting the condition of NRCMs, oxidative stress level, and mitochondrial function were evaluated. In addition, the expression and phosphorylation of 14-3-3η and AMPKα/mTOR/ULK1, and autophagy markers (LC3II, P62) and the abundance of autophagy lysosomes were detected. Results revealed that Lut pretreatment alleviated anoxia- induced damage in NRCMs, that is, Lut pretreatment could increase cell viability, decrease LDH activity and apoptosis, suppressed ROS generation and oxidative stress, restored intracellular ATP levels, stabilized MMP levels, and inhibited mPTP opening. Furthermore, Lut pretreatment could enhance autophagy via upregulating 14-3-3η, LC3II expression and increasing p-AMPKα/AMPKα and p-ULK1/ULK1 level, whereas P62 expression and p-mTOR/mTOR level decreased; the fluorescence intensity of autolysosomes also increased. However, in the NRCMs treated with pAD/14-3-3η RNAi or incubated with 3-MA (an autophagy inhibitor), the abovementioned effects of Lut pretreatment were reduced. Taken together, Lut pretreatment could enhance autophagy by upregulating 14-3-3η expression to influence the AMPKα-mTOR/ ULK1 pathway against anoxia-induced damage in NRCMs.

Bisphenol A induces apoptosis and autophagy in murine osteocytes MLO-Y4: Involvement of ROS-mediated mTOR/ULK1 pathway.

Bisphenol A (BPA) is a widely environmental endocrine disruptor. The accumulated BPA in humans is toxic to osteoblasts and osteoclasts, but few studies focused on the effects of BPA on osteocytes, the most abundant bone cell type, contributing to the development and metabolism of bone. Here, we reported that BPA (50, 100, 200 µmol/L) inhibited the cell viability of osteocytes MLO-Y4, promoted G0/G1 phase arrest and apoptosis in a dose-dependent manner. BPA treatment significantly increased the levels of autophagy-regulated proteins including Beclin-1 and LC3-II along with the decrease of p62, accompanied by the elevation of autophagy flux and the accumulation of acidic vacuoles, which was blocked by the autophagy inhibitor bafilomycin A1 (BafA1). Furthermore, BPA significantly inhibited the mammalian target of rapamycin (mTOR) and activated Unc-51 like autophagy activating kinase 1 (ULK1) signaling, leading to the decreased p-mTOR/mTOR ratio and the increased p-ULK1/ULK1 ratio. The mTOR activator MHY1485 (MHY) or the ULK1 inhibitor SBI-0206965 (SBI) prevented autophagy and enhanced apoptosis caused by BPA, respectively. In addition, BPA increased the levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) and decreased antioxidant enzymes nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels, resulting in oxidative stress. The ROS scavenger N-acetylcysteine (NAC) attenuated BPA-induced the mTOR/ULK1 pathway activation, apoptosis and autophagy. Collectively, ROS-mediated mTOR/ULK1 signaling is involved in BPA-induced apoptosis and autophagy in osteocytes MLO-Y4. Our data first provide in vitro evidence that apoptosis and autophagy as cellular mechanisms for the toxic effect of BPA on osteocytes, thereby advancing our understanding of the potential role of osteocytes in the adverse effect of BPA on bone health.

An aqueous extract of Prunella vulgaris L. inhibits the growth of papillary thyroid carcinoma by inducing autophagy in vivo and in vitro.

The continued global rise in papillary thyroid carcinoma (PTC) combined with potential adverse effects of regular treatments calls for an alternative therapy. Prunella vulgaris L. (PV) is commonly used as a herbal remedy for thyroid diseases in China, but its influence on PTC is unclear. This study investigated the effect of PV aqueous extract on PTC and its underlying mechanism using a mouse xenograft model and the human PTC cell line K1. PV suppressed tumor growth in PTC-bearing mice at 0.05 and 0.1 g/kg bw, accompanied by improvements in autophagy-related protein expressions in xenografts. In K1 cells, PV inhibited cell growth and induced autophagic flux, manifesting as changes in autophagy-related proteins, the presence of autophagosomes, and a further increase in LC3-II by co-incubation with bafilomycin A1. Autophagy inhibitor 3-methyladenine ameliorated the autophagic cell death caused by PV. The mammalian target of rapamycin (mTOR) activator MHY1485 blocked the antiproliferative activity of PV by regulating mTOR, unc-51-like autophagy activating kinase 1 (ULK1), autophagosomes formation, and autophagy-related proteins. The adenosine monophosphate-activated protein kinase (AMPK) inhibitor compound C attenuated PV-induced inhibition of mTOR. Our results suggest that PV inhibits the growth of PTC in vivo and in vitro via autophagy, which is associated with the AMPK/mTOR/ULK1 pathway. Thus, PV has the potential to function as a therapeutic agent against PTC.

Aurora-B knockdown inhibits osteosarcoma metastasis by inducing autophagy via the mTOR/ULK1 pathway.

BACKGROUND: Autophagy plays an essential role in metastasis of malignancies. Although our studies showed that Aurora-B facilitate pulmonary metastasis in OS, the mechanism of Aurora-B kinase on autophagy and metastasis in OS has not been explored. METHODS: Clinical-pathological parameters and follow-up information was collected in OS patients. Immunohistochemical staining was performed to detect Aurora-B and LC3 protein in OS tissues. Short hairpin RNA transfection was used to silence Aurora-B in OS cells. Real-time quantitative PCR (RT-qPCR) was performed to detect Aurora-B mRNA expression in OS cells. Aurora-B and autophagy related protein were measured by Western blot. Transmission electron microscopy and laser scanning confocal microscopy were performed to observe the formation of autophagosomes and autolysosomes. Migratory and invasive ability of OS cells were measured by Wound healing and transwell assays. Orthotopic xenograft model was used to evaluate the effect of autophagy mediated by Aurora-B inhibition on pulmonary metastasis of OS. RESULTS: The elevated expression of Aurora-B protein in OS tissues negatively associated with the overall survival of OS patients. Further investigation has found that Aurora-B expression was negatively correlative with autophagy related protein LC3 in OS patient tissues. Knockdown Aurora-B stimulates autophagy and inhibits migratory and invasive ability of OS cells. Mechanistically, Aurora-B knockdown suppressed the mTOR/ULK1 signaling pathway and reactivation of the mTOR/ULK1 pathway decreased autophagy level. Furthermore, the inhibition effect of silencing Aurora-B on migration and invasion of OS was reversed by chloroquine and mTOR activator in vitro and vivo. CONCLUSIONS: Our results suggest that silencing of Aurora-B stimulate autophagy via decreasing mTOR/ULK1 and result in inhibiting OS metastasis. Targeted Aurora-B/mTOR/ULK1 pathway may be a promising treatment strategy for OS patients.

AMPK/mTOR/ULK1 Axis-Mediated Pathway Participates in Apoptosis and Autophagy Induction by Oridonin in Colon Cancer DLD-1 Cells.

BACKGROUND: Oridonin has been demonstrated to exert strong antitumor activities in various types of human cancers. Our previous study established that oridonin induced the apoptosis of and exerted an inhibitory effect on colon cancer cells in vitro and in vivo. However, the mechanisms behind the antitumor effects of oridonin on colorectal cancer are not clearly known. This study explored whether autophagy was involved in antitumorigenesis effects caused by the usage of oridonin in colon cancer and examined whether the AMPK/mTOR/ULK1 signaling pathway was involved in this process. METHODS: Cell viability was determined using CCK-8 assay. The distribution of cell apoptosis was evaluated using flow cytometry. RT-PCR and Western blotting analysis were conducted to identify the key target genes and proteins involved in the AMPK/mTOR cascade. AMPK siRNA was used to disturb AMPK expression. A DLD-1 cell orthotopic transplantation tumor model was established to explore the anti-cancer effects in vivo. RESULTS: Oridonin exhibited a suppressive effect on DLD-1 cells in a concentration- and time-dependent manner. Additionally, in a dose-dependent manner, oridonin induced cell apoptosis via inducing the protein expression levels of cleaved caspase-3, cleaved PARP and stimulated autophagy by increasing protein expression levels of Becin1, LC3-II, decreasing protein expression levels of LC3-I, p62, which were respectively attenuated and elevated by autophagy inhibitor 3-MA. Furthermore, oridonin upregulated the expression level of p-AMPK and downregulated the expression levels of p-mTOR, p-ULK1 in the DLD-1 cells in a dose-dependent manner. Moreover, knockdown of AMPK by a specific siRNA reversed the expression levels of proteins involved in the AMPK/mTOR pathway, autophagy and apoptosis. In addition, outcomes from the in vivo experiments also showed that oridonin treatment significantly repressed tumorigenic growth of DLD-1 cells without any side effects, which was accompanied by the upregulation of p-AMPK, LC3-II, active caspase-3 protein expression levels and the downregulation of p-mTOR and p-ULK1 protein expression levels. CONCLUSION: This study demonstrated that oridonin induced apoptosis and autophagy of colon cancer DLD-1 cells via regulating the AMPK/mTOR/ULK1 pathway, which indicated that oridonin may be used as a novel therapeutic intervention for patients with colorectal cancer.

Vitexin reverses the autophagy dysfunction to attenuate MCAO-induced cerebral ischemic stroke via mTOR/Ulk1 pathway.

Stroke, as a kind of acute cerebrovascular diseases, has greatly influenced the patients' quality of life and left a huge public health burden. Vitexin is a flavone C-glycoside (apigenin-8-C-?-D-glucopyranoside) present in several medicinal and other plants. This study aims to explore the role of vitexin in middle cerebral artery occlusion (MCAO)-induced cerebral ischemic stroke. The results showed that the MCAO-induced brain infarction was obviously decreased by vitexin. And the abnormal protein levels of Caspase-3, Bcl-2-associated X protein (Bax), antigen identified by monoclonal antibody (Ki-67) and B cell lymphoma 2 (Bcl-2) in MCAO model rats were reversed by vitexin. Further research indicated that vitexin alleviated MCAO-induced oxidative injury by reducing the levels of lactate dehydrogenase (LDH), malondialdehyde (MDA) and nitric Oxide (NO). In addition, vitexin attenuated the secretion of pro-inflammatory cytokine (interleukin (IL)-6 and tumor necrosis factor alpha (TNF-?)) and increased anti-inflammatory cytokine (IL-10) production to ameliorate MCAO-induced inflammation. What's more, vitexin repressed the MCAO-induced autophagy through mechanistic target of rapamycin (mTOR)/Ulk1 pathway. Specifically, the MCAO-induced decreased expression of mTOR, peroxisome proliferator-activated receptor ? (PPAR?) and p62 were inhibited by vitexin. At the same time, MCAO-induced increased expression of Ulk1, Beclin1 and rate of LC3?/LC3? also were repressed by vitexin. But the inhibition of vitexin on the MCAO-induced oxidative injury, apoptosis and inflammation were reversed by rapamycin. These results implied that vitexin suppressed the autophagy dysfunction to attenuate MCAO-induced cerebral ischemic stroke via mTOR/Ulk1 pathway.

Fucoxanthin, the constituent of Laminaria japonica, triggers AMPK-mediated cytoprotection and autophagy in hepatocytes under oxidative stress.

BACKGROUND: Laminaria japonica has frequently been used as a food supplement and drug in traditional oriental medicine. Among the major active constituents responsible for the bioactivities of L. japonica, fucoxanthin (FX) has been considered as a potential antioxidant. This study was conducted to examine the effects of L. japonica extract (LJE) or FX against oxidative stress on hepatocytes and to elucidate the overall their cellular mechanisms of the effects. METHODS: We constructed an in vitro model with the treatment of arachidonic acid (AA) + iron in HepG2 cells to stimulate the oxidative damage. The cells were pre-treated with LJE or FX for 1 h, and incubated with AA + iron. The effect on oxidative damage and cellular mechanisms of LJE or FX were assessed by cytological examination and several biochemical assays under conditions with or without kinase inhibitiors. RESULTS: LJE or FX pretreatment effectively blocked the pathological changes caused by AA + iron treatment, such as cell death, altered expression of apoptosis-related proteins such as procaspase-3 and poly (ADP-ribose) polymerase, and mitochondria dysfunction. Moreover, FX induced AMPK activation and AMPK inhibitor, compound C, partially reduced the protective effect of FX on mitochondria dysfunction. Consistent with AMPK activation, FX increased the protein levels of autophagic markers (LC3II and beclin-1) and the number of acridine orange stained cells, and decreased the phosphorylation of mTOR and simultaneously increased the phosphorylation of ULK1. And the inhibition of autophagy by 3-methylanine or bafilomycin A1 partially inhibited the protective effect of FX on mitochondria dysfunction. CONCLUSION: These findings suggest that FX have the function of being a hepatic protectant against oxidative damages through the AMPK pathway for the control of autophagy.

Salvianolic acid B induces autophagic cell death in giloma through mTOR/Ulk1 signaling pathway / 中国免疫学杂志

Objective:To evaluate the effects and underlying molecular mechanism of salvianolic acid B(Sal B) on autophagy in glioma cell.Methods:The C6 cells were treated with Sal B at a concentration ranging from 0 to 400 μmol/L and the cell viability were measured by CCK8 assay.Flow cytometry was performed for apoptosis,Western blot assay for protein expression and the expression of LC3 was calculated by immunofluorescence.Results:The cell viability was weakened by Sal B at a concentration of 100 μmol/L, thus,the concentration of 10,20 and 50 μmol/L were selected for further experiment.Sal B dose-dependedly induced C6 cell apoptosis and the expression of caspase-3 and Bax,notably decreased the protein level of Bcl-2 and Ki67.Meanwhile,Sal B significantly up-regulated the expression level of Atg5,Atg7,Atg12 and Beclin1,increased the ratio of LC3Ⅱ/Ⅰand the amount of LC3-labeled puncta per cell,and down-regulated the expression of p62.In addition,the protein level of mTOR was makedly decreased by Sal B and Sal B induced the expression of Ulk1.Conclusion:Sal B induces autophagic cell death in glioma cell through mTOR/Ulk1 signaling pathway.