scholarly journals Development of a pH-responsive polymersome inducing endoplasmic reticulum stress and autophagy blockade

2020 ◽  
Vol 6 (31) ◽  
pp. eabb8725 ◽  
Author(s):  
Funeng Xu ◽  
Xilin Li ◽  
Xuehui Huang ◽  
Jingmei Pan ◽  
Yi Wang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Tumor Metastasis ◽  
Focal Adhesions ◽  
Matrix Metalloproteinase 2 ◽  
Autophagic Flux ◽  
Ph Responsive ◽  
Ph Response ◽  
Function Mechanism ◽  
Inhibit Tumor Metastasis

Autophagy is involved in the occurrence and development of tumors. Here, a pH-responsive polymersome codelivering hydroxychloroquine (HCQ) and tunicamycin (Tuni) drugs is developed to simultaneously induce endoplasmic reticulum (ER) stress and autophagic flux blockade for achieving an antitumor effect and inhibiting tumor metastasis. The pH response of poly(β-amino ester) and HCQ synergistically deacidifies the lysosomes, thereby blocking the fusion of autophagosomes and lysosomes and lastly blocking autophagic flux. The function mechanism of regulating autophagy was systematically investigated on orthotopic luciferase gene–transfected, 4T1 tumor–bearing BALB/c mice through Western blot and immunohistochemistry analyses. The Tuni triggers ER stress to regulate the PERK/Akt signaling pathway to increase the autophagic level. The “autophagic stress” generated by triggering ER stress–induced autophagy and blocking autophagic flux is effective against tumors. The reduced expression of matrix metalloproteinase-2 due to ER stress and reduced focal adhesions turnover due to the blockade of autophagic flux synergistically inhibit tumor metastasis.

scholarly journals Reticulon proteins modulate autophagy of the endoplasmic reticulum in maize endosperm

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Xiaoguo Zhang ◽  
Xinxin Ding ◽  
Richard Scott Marshall ◽  
Julio Paez-Valencia ◽  
Patrick Lacey ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Lipid Droplets ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Maize Endosperm ◽  
Transmembrane Segments ◽  
C Terminus ◽  
Er Homeostasis ◽  
Dose Dependent

Reticulon (Rtn) proteins shape tubular domains of the endoplasmic reticulum (ER), and in some cases are autophagy receptors for selective ER turnover. We have found that maize Rtn1 and Rtn2 control ER homeostasis and autophagic flux in endosperm aleurone cells, where the ER accumulates lipid droplets and synthesizes storage protein accretions metabolized during germination. Maize Rtn1 and Rtn2 are expressed in the endosperm, localize to the ER, and re-model ER architecture in a dose-dependent manner. Rtn1 and Rtn2 interact with Atg8a using four Atg8-interacting motifs (AIMs) located at the C-terminus, cytoplasmic loop, and within the transmembrane segments. Binding between Rtn2 and Atg8 is elevated upon ER stress. Maize rtn2 mutants display increased autophagy and up-regulation of an ER stress-responsive chaperone. We propose that maize Rtn1 and Rtn2 act as receptors for autophagy-mediated ER turnover, and thus are critical for ER homeostasis and suppression of ER stress.

scholarly journals IRE1-mTOR-PERK Axis Coordinates Autophagy and ER Stress-Apoptosis Induced by P2X7-Mediated Ca2+ Influx in Osteoarthritis

2021 ◽  
Vol 9 ◽  
Author(s):  
Zihao Li ◽  
Ziyu Huang ◽  
He Zhang ◽  
Jinghan Lu ◽  
Yingliang Wei ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Purinergic Receptor ◽  
Cruciate Ligament ◽  
Critical Role ◽  
Moderate Intensity ◽  
Autophagic Flux ◽  
Moderate Intensity Exercise ◽  
Mtor Inhibition ◽  
Time Points

Moderate-intensity exercise can help delay the development of osteoarthritis (OA). Previous studies have shown that the purinergic receptor P2X ligand gated ion channel 7 (P2X7) is involved in OA development and progression. To investigate the effect of exercise on P2X7 activation and downstream signaling in OA, we used the anterior cruciate ligament transection (ACLT)-induced OA rat model and primary chondrocyte culture system. Our in vivo experiments confirmed that treadmill exercise increased P2X7 expression and that this effect was more pronounced at the later time points. Furthermore, P2X7 activation induced endoplasmic reticulum (ER) stress and increased the expression levels of ER stress markers, such as 78 kDa glucose-regulated protein (GRP78), protein kinase R-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme-1 (IRE1), and activating transcription factor 6 (ATF6). At the early time points, IRE1 and PERK were activated, and mTOR was inhibited. At the later time points, mTOR was activated, mediating PERK to promote ER stress-apoptosis, whereas IRE1 and autophagy were inhibited. To confirm our observations in vitro, we treated primary chondrocytes with the P2X7 agonist benzoylbenzoyl-ATP (Bz-ATP). Our results confirmed that P2X7-mediated Ca2+ influx activated IRE1-mediated autophagic flux and induced PERK-mediated ER stress-apoptosis. To further investigate the role of P2X7 in OA, we injected mTOR antagonist rapamycin or P2X7 antagonist A740003 into the knee joints of ACLT rats. Our results demonstrated that mTOR inhibition induced autophagy, decreased apoptosis, and reduced cartilage loss. However, injection of mTOR agonist MHY1485 or Bz-ATP had the opposite effect. In summary, our results indicated that during the early stages of moderate-intensity exercise, P2X7 was activated and autophagic flux was increased, delaying OA development. At the later stages, P2X7 became over-activated, and the number of apoptotic cells increased, promoting OA development. We propose that the IRE1-mTOR-PERK signaling axis was involved in the regulation of autophagy inhibition and the induction of apoptosis. Our findings provide novel insights into the positive and preventative effects of exercise on OA, suggesting that the intensity and duration of exercise play a critical role. We also demonstrated that on a molecular level, P2X7 and its downstream pathways could be potential therapeutic targets for OA.

scholarly journals L-Ascorbic Acid Inhibits Breast Cancer Growth by Inducing IRE/JNK/CHOP-Related Endoplasmic Reticulum Stress-Mediated p62/SQSTM1 Accumulation in the Nucleus

Nutrients ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1351 ◽  
Author(s):  
Youn Kyung Choi ◽  
Jung-Il Kang ◽  
Sanghoon Han ◽  
Young Ree Kim ◽  
Jaemin Jo ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Ascorbic Acid ◽  
Er Stress ◽  
Cancer Cells ◽  
Cancer Growth ◽  
Autophagic Flux ◽  
Sequestosome 1 ◽  
Breast Cancer Growth

Anticancer effects of L-ascorbic acid (Vitamin C, L-AA) have been reported in various types of cancers. L-AA intake reduces breast cancer recurrence and mortality; however, the role of L-AA in the treatment of breast cancer remains poorly understood. In this study, we investigated the effect and mechanism action of L-AA on breast cancer growth. L-AA inhibited the growth of breast cancer cells by inducing apoptotic cell death at the evaluated treatment concentrations without affecting normal cells. Moreover, L-AA induces autophagosome formation via regulation of mammalian target of rapamycin (mTOR), Beclin1, and autophagy-related genes (ATGs) and increased autophagic flux. Notably, we observed that L-AA increased p62/SQSTM1 (sequestosome 1) protein levels. Accumulation of p62 protein in cancer cells in response to stress has been reported, but its role in cancer regulation remains controversial. Here, we demonstrated that L-AA-induced p62 accumulation is related to L-AA-induced breast cancer growth inhibition. Furthermore, L-AA induced endoplasmic reticulum (ER) stress via the IRE–JNK–CHOP (inositol-requiring endonuclease–c-Jun N-terminal kinase–C/EBP homologous protein) signaling pathways, which increased the nuclear levels of p62/SQSTM1. These findings provide evidence that L-AA-induced ER stress could be crucial for p62 accumulation-dependent cell death, and L-AA can be useful in breast cancer treatment.

scholarly journals Endoplasmic Reticulum Stress Contributed to Dipyridamole-Induced Impaired Autophagic Flux and Glioma Apoptosis

2022 ◽  
Vol 23 (2) ◽  
pp. 579
Author(s):  
Cheng-Yi Chang ◽  
Chih-Cheng Wu ◽  
Jiaan-Der Wang ◽  
Su-Lan Liao ◽  
Wen-Ying Chen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Apoptotic Cell ◽  
Glioma Cells ◽  
Apoptotic Cell Death ◽  
Autophagic Flux ◽  
Intracellular Camp ◽  
Cell Proliferation Inhibition ◽  
Camp Levels

Elevation of intracellular cAMP levels has been implicated in glioma cell proliferation inhibition, differentiation, and apoptosis. Inhibition of phosphodiesterase is a way to elevate intracellular cAMP levels. The present study aimed to investigate the anti-glioma potential of dipyridamole, an inhibitor of phosphodiesterase. Upon treatment with dipyridamole, human U87 glioma cells decreased cell viability, clonogenic colonization, migration, and invasion, along with Noxa upregulation, Endoplasmic Reticulum (ER) stress, impaired autophagic flux, Yes-associated Protein 1 (YAP1) phosphorylation, and YAP1 reduction. Pharmacological and genetic studies revealed the ability of dipyridamole to initiate Noxa-guided apoptosis through ER stress. Additionally, the current study further identified the biochemical role of YAP1 in communicating with ER stress and autophagy under situations of dipyridamole treatment. YAP1 promoted autophagy and protected glioma cells from dipyridamole-induced apoptotic cell death. Dipyridamole impaired autophagic flux and rendered glioma cells more vulnerable to apoptotic cell death through ER stress-inhibitable YAP1/autophagy axis. The overall cellular changes caused by dipyridamole appeared to ensure a successful completion of apoptosis. Dipyridamole also duplicated the biochemical changes and apoptosis in glioma T98G cells. Since dipyridamole has additional biochemical and pharmacological properties, further research centered on the anti-glioma mechanisms of dipyridamole is still needed.

scholarly journals Astragaloside-IV Alleviates Heat-Induced Inflammation by Inhibiting Endoplasmic Reticulum Stress and Autophagy

2017 ◽  
Vol 42 (2) ◽  
pp. 824-837 ◽  
Author(s):  
Zhiwei Dong ◽  
Jian Zhou ◽  
Ying Zhang ◽  
Yajie Chen ◽  
Zichen Yang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Inflammatory Responses ◽  
Fluorescence Emission ◽  
Inhalation Injury ◽  
Autophagic Flux ◽  
Protective Effects ◽  
Astragaloside Iv ◽  
Imaging Results ◽  
Tnf Α

Background: Thermal injury is the main cause of pulmonary disease in stroke after burn and can be life threatening. Heat-induced inflammation is an important factor that triggers a series of induces pathological changes. However, this mechanism underlying heat-induced inflammation in thermal inhalation injury remains unclear. Studies have revealed that astragaloside-IV (AS-IV), a natural compound extracted from Astragalus membranaceus, has protective effects in inflammatory diseases. Here, we investigated whether the protective effects of AS-IV occur because of the suppression of heat-induced endoplasmic reticulum (ER) stress and excessive autophagy Methods: AS-IV was administered to Wistar rats after thermal inhalation injury and 16HBE140-cells were treated with AS-IV. TNF-α, IL-6, and IL-8 levels were determined by ELISA and real-time PCR. ER stress and autophagy were determined by western blot. Autophagic flux was measured by recording the fluorescence emission of the fusion protein mRFP-GFP-LC3 by dynamic live-cell imaging. Results: AS-IV had protective effects against heat-induced reactive oxygen species production and attenuated ER stress. AS IV alleviated heat-induced excessive autophagy in vitro and in vivo. Excessive autophagy was attenuated by the PERK inhibitor GSK2656157 and eIF2α siRNA, suggesting that heat stress-induced autophagy can activate the PERK-eIF2α pathway. Beclin 1 and Atg5 siRNAs inhibited the upregulation of the inflammatory cytokines TNF-α, IL-6, and IL-8 after heat exposure. Conclusions: Thus, AS-IV may attenuate inflammatory responses by disrupting the crosstalk between autophagy and the PERK-eIF2α pathway and may be an ideal agent for treating inflammatory pulmonary diseases.

scholarly journals JAK/STAT inhibitor therapy partially rescues the lipodystrophic autoimmune phenotype in Clec16a KO mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rahul Pandey ◽  
Marina Bakay ◽  
Bryan P. Strenkowski ◽  
Heather S. Hain ◽  
Hakon Hakonarson
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Whole Body ◽  
Autophagic Flux ◽  
Loss Of Function ◽  
Proinflammatory Mediators ◽  
Glucose Tolerant ◽  
Novel Target ◽  
Adipose Inflammation ◽  
Antibody Levels

AbstractCLEC16A is implicated in multiple autoimmune diseases. We generated an inducible whole-body knockout (KO), Clec16aΔUBC mice to address the role of CLEC16A loss of function. KO mice exhibited loss of adipose tissue and severe weight loss in response to defective autophagic flux and exaggerated endoplasmic reticulum (ER) stress and robust cytokine storm. KO mice were glucose tolerant and displayed a state of systemic inflammation with elevated antibody levels, including IgM, IgA, Ig2b and IgG3, significantly reduced circulating insulin levels in the presence of normal food consumption. Metabolic analysis revealed disturbances in the lipid profile, white adipose decreasing concomitantly with enhanced inflammatory response, and energy wasting. Mechanistically, endoplasmic reticulum (ER) stress triggers excessive hormone sensitive lipases (HSL) mediated lipolysis which contributes to adipose inflammation via activation of JAK-STAT, stress kinases (ERK1/2, P38, JNK), and release of multiple proinflammatory mediators. Treatment with a JAK-STAT inhibitor (tofacitinib) partially rescued the inflammatory lipodystrophic phenotype and improved survival of Clec16aΔUBC mice by silencing cytokine release and modulating ER stress, lipolysis, mitophagy and autophagy. These results establish a mechanistic link between CLEC16A, lipid metabolism and the immune system perturbations. In summary, our Clec16aΔUBC mouse model highlights multifaceted roles of Clec16a in normal physiology, including a novel target for weight regulation and mutation-induced pathophysiology.

Abstract 15689: Activation of PKR-Like Endoplasmic Reticulum Kinase is Required for Autophagy Stimulation and Cardiomyocyte Survival During Acute Myocardial Ischemia

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Sebastiano Sciarretta ◽  
Narayani Nagarajan ◽  
Derek Yee ◽  
Peiyong Zhai ◽  
Priya Umapathi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Myocardial Ischemia ◽  
Er Stress ◽  
Cellular Response ◽  
Degradation Mechanism ◽  
Dominant Negative ◽  
Autophagic Flux ◽  
Area At Risk ◽  
Energy Stress ◽  
Energy Deprivation

PKR-like endoplasmic reticulum (ER) kinase (PERK) is an ER-resident serine/threonine kinase that regulates the cellular response to ER stress and energy deprivation. Under stress, PERK activation can be either protective or detrimental. We studied for the first time whether PERK regulates cardiomyocyte (CM) survival and death during myocardial ischemia, which is characterized by both ER and energy stress. We found that PERK is significantly activated after 30 minutes of myocardial ischemia (2.4 ± 0.04-fold, p<0.001), as shown by its increased phosphorylation status. After 3 hours of ischemia, mice with cardiac-specific overexpression of dominant-negative PERK (Tg-DN-PERK) displayed a significant increase in infarct size/area at risk with respect to non-transgenic (NTg) mice (66.4 ± 4.1% vs. 38.5 ± 6.8%, p<0.05), indicating that ischemia-induced PERK activation is cardioprotective. PERK signaling regulates autophagy in cancer cells. Autophagy is an intracellular degradation mechanism that promotes CM survival during ischemia by relieving both energy and ER stress. We found that autophagy activation during ischemia is abrogated in the hearts of Tg-DN-PERK with respect to NTg, as indicated by reduced LC3-II accumulation (0.71 ± 0.05-fold, p<0.01). Consistently, CMs with adenovirus-mediated overexpression of DN-PERK displayed reduced LC3-II accumulation (0.69 ± 0.1-fold vs. control CMs, p<0.05) after 4 hours of glucose deprivation (GD) in vitro, a condition that mimics ischemia-induced energy stress. A similar result was also observed after bafilomycin A1 treatment to test autophagic flux. These data indicate that PERK is required for autophagy activation and flux during CM ischemia and GD. Finally, we saw that DN-PERK overexpression significantly promotes CM death after GD, as shown by propidium iodide assay (2.01 ± 0.25-fold vs. control CMs, p<0.05). However, co-overexpression of Atg7, which activates autophagy, significantly reduced cell death induced by DN-PERK (-61%, p<0.05). These data suggest that autophagy inhibition partly mediates the detrimental effects of PERK inhibition during energy stress. In conclusion, our study demonstrates that PERK activation is required for autophagy activation and CM survival during ischemia.

scholarly journals The aryl hydrocarbon receptor reduces LC3II expression and controls endoplasmic reticulum stress

2020 ◽  
Author(s):  
Necola Guerrina ◽  
Noof Aloufi ◽  
Fangyi Shi ◽  
Kashmira Prasade ◽  
Caitlin Mehrotra ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Aryl Hydrocarbon Receptor ◽  
Cigarette Smoke ◽  
A549 Cells ◽  
Lung Fibroblasts ◽  
Lung Cells ◽  
Autophagic Flux ◽  
Aryl Hydrocarbon

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor whose physiological function is poorly understood. The AhR is highly expressed in barrier organs such as the skin, intestine and lung. The lungs are continuously exposed to environmental pollutants such as cigarette smoke (CS) that can induce cell death mechanisms such as apoptosis, autophagy and endoplasmic reticulum (ER) stress. CS also contains toxicants that are AhR ligands. We have previously shown that the AhR protects against apoptosis, but whether the AhR also protects against autophagy or ER stress is not known. Using cigarette smoke extract (CSE) as our in vitro surrogate of environmental tobacco exposure, we first assessed the conversion of LC3I to LC3II, a classic feature of both autophagic and ER stress-mediated cell death pathways. LC3II was elevated in CSE-exposed lung structural cells (mouse lung fibroblasts [MLFs], MLE12 and A549 cells) when AhR was absent. However, this heightened LC3II expression could not be explained by increased expression of key autophagy genes (Gabarapl1, Becn1, Map1lc3b), upregulation of upstream autophagic machinery (Atg5-12, Atg3) or by impaired autophagic flux, suggesting that LC3II may be autophagy-independent. This was further supported by the absence of autophagosomes in Ahr-/- lung cells. However, Ahr-/- lung cells had widespread ER-dilation, elevated expression of the ER stress markers CHOP and GADD34 and an accumulation of ubiquitinated proteins. These findings collectively illustrate a novel role for the AhR in attenuating ER stress by a mechanism that may be autophagy-independent.

Elevating sestrin2 attenuates endoplasmic reticulum stress and improves functional recovery through autophagy activation after spinal cord injury

2020 ◽  
Author(s):  
Yao Li ◽  
Jing Zhang ◽  
Kailiang Zhou ◽  
Ling Xie ◽  
Guangheng Xiang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Functional Recovery ◽  
Sensory Function ◽  
Autophagic Flux ◽  
Critical Determinant ◽  
Cord Injury

Abstract Background Spinal cord injury (SCI) is a devastating central neurological trauma that causes a loss of motor and sensory function. Sestrin2, also known as hypoxia inducible gene 95 (Hi95), is emerging as a critical determinant of cell homeostasis in response to cellular stress. However, the role of sestrin2 in neuron response to endoplasmic reticulum (ER) stress and potential mechanism remains undefined. In this study, we investigated the effects of sestrin2 on ER stress and delineated a underlying molecular mechanism after SCI. Methods The induction of sestrin2 after traumatic injury and ER stress insult were investigated in vitro and in vivo. West blot and immunofluorescence were used to analyze the potential mechanisms of sestrin2 on autophagy and ER stress after SCI. Behavior assessment were used to evaluated the effect of sestrin2 on function recovery in vivo. Results Elevated sestrin2 is a protective process in neurons against chemical ER stress induced by tunicamycin (TM) or traumatic invasion. While treatment with PERK inhibitor or knockdown of ATF4 reduces sestrin2 expression upon ER stress. In addition, overexpression of sestrin2 limits ER stress, promotes the survival of neuron and improves functional recovery after SCI, which is associated with activation of autophagy and restoration of autophagic flux mediated by sestrin2. Meanwhile, sestrin2 activates autophagy dependent on AMPK-mTOR signaling pathway. Consistently, inhibition of AMPK abrogates the effect of sestrin2 on activation of autophagy, and blockage of autophagic flux abolishes the effect of sestrin2 on limiting ER stress and neural death. Conclusion Upregulation of sestrin2 as an important resistance mechanism of neuron to ER stress, and its potential role as a therapeutic target for SCI.

scholarly journals Zinc Attenuates the Cytotoxicity of Some Stimuli by Reducing Endoplasmic Reticulum Stress in Hepatocytes

2019 ◽  
Vol 20 (9) ◽  
pp. 2192 ◽  
Author(s):  
Masashi Kusanaga ◽  
Shinji Oe ◽  
Noriyoshi Ogino ◽  
Sota Minami ◽  
Koichiro Miyagawa ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Er Stress ◽  
Inclusion Body ◽  
Cultured Cells ◽  
Autophagic Flux ◽  
Body Formation ◽  
Excess Copper ◽  
Inclusion Body Formation ◽  
Cellular Integrity ◽  
Er Homeostasis

Zinc is an essential trace element and plays critical roles in cellular integrity and biological functions. Excess copper induced both oxidative stress and endoplasmic reticulum (ER) stress in liver-derived cultured cells. Excess copper also induced impairment of autophagic flux at the step of autophagosome–lysosome fusion, as well as Mallory–Denk body (MDB)-like inclusion body formation. Zinc ameliorated excess copper-induced impairment of autophagic flux and MDB-like inclusion body formation via the maintenance of ER homeostasis. Furthermore, zinc also ameliorated free fatty acid-induced impairment of autophagic flux. These results indicate that zinc may be able to protect hepatocytes from various ER stress-related conditions.

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