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Redox Biology Jun 2022Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are important mechanisms of atrial remodeling, predisposing to the development of atrial fibrillation...
RATIONALE
Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are important mechanisms of atrial remodeling, predisposing to the development of atrial fibrillation (AF) in type 2 diabetes mellitus (T2DM). However, the molecular mechanisms underlying these processes especially their interactions have not been fully elucidated.
OBJECTIVE
To explore the potential role of ER stress-mitochondrial oxidative stress in atrial remodeling and AF induction in diabetes.
METHODS AND RESULTS
Mouse atrial cardiomyocytes (HL-1 cells) and rats with T2DM were used as study models. Significant ER stress was observed in the diabetic rat atria. After treatment with tunicamycin (TM), an ER stress agonist, mass spectrometry (MS) identified several known ER stress and calmodulin proteins, including heat shock protein family A (HSP70) member [HSPA] 5 [GRP78]) and HSPA9 (GRP75, glucose-regulated protein 75). In situ proximity ligation assay indicated that TM led to increased protein expression of the IP3R1-GRP75-VDAC1 (inositol 1,4,5-trisphosphate receptor 1-glucose-regulated protein 75-voltage-dependent anion channel 1) complex in HL-1 cells. Small interfering RNA silencing of GRP75 in HL-1 cells and GRP75 conditional knockout in a mouse model led to impaired calcium transport from the ER to the mitochondria and alleviated mitochondrial oxidative stress and calcium overload. Moreover, GRP75 deficiency attenuated atrial remodeling and AF progression in Myh6-Cre/Hspa9 + TM mice.
CONCLUSIONS
The IP3R1-GRP75-VDAC1 complex mediates ER stress-mitochondrial oxidative stress and plays an important role in diabetic atrial remodeling.
Topics: Animals; Atrial Remodeling; Calcium; Diabetes Mellitus, Type 2; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Glucose; HSP70 Heat-Shock Proteins; Inositol 1,4,5-Trisphosphate Receptors; Membrane Proteins; Mice; Oxidative Stress; Rats; Tunicamycin; Voltage-Dependent Anion Channel 1
PubMed: 35344886
DOI: 10.1016/j.redox.2022.102289 -
Autophagy Oct 2014Transient cerebral ischemia leads to endoplasmic reticulum (ER) stress. However, the contributions of ER stress to cerebral ischemia are not clear. To address this...
Transient cerebral ischemia leads to endoplasmic reticulum (ER) stress. However, the contributions of ER stress to cerebral ischemia are not clear. To address this issue, the ER stress activators tunicamycin (TM) and thapsigargin (TG) were administered to transient middle cerebral artery occluded (tMCAO) mice and oxygen-glucose deprivation-reperfusion (OGD-Rep.)-treated neurons. Both TM and TG showed significant protection against ischemia-induced brain injury, as revealed by reduced brain infarct volume and increased glucose uptake rate in ischemic tissue. In OGD-Rep.-treated neurons, 4-PBA, the ER stress releasing mechanism, counteracted the neuronal protection of TM and TG, which also supports a protective role of ER stress in transient brain ischemia. Knocking down the ER stress sensor Eif2s1, which is further activated by TM and TG, reduced the OGD-Rep.-induced neuronal cell death. In addition, both TM and TG prevented PARK2 loss, promoted its recruitment to mitochondria, and activated mitophagy during reperfusion after ischemia. The neuroprotection of TM and TG was reversed by autophagy inhibition (3-methyladenine and Atg7 knockdown) as well as Park2 silencing. The neuroprotection was also diminished in Park2(+/-) mice. Moreover, Eif2s1 and downstream Atf4 silencing reduced PARK2 expression, impaired mitophagy induction, and counteracted the neuroprotection. Taken together, the present investigation demonstrates that the ER stress induced by TM and TG protects against the transient ischemic brain injury. The PARK2-mediated mitophagy may be underlying the protection of ER stress. These findings may provide a new strategy to rescue ischemic brains by inducing mitophagy through ER stress activation.
Topics: Animals; Apoptosis; Brain Ischemia; Endoplasmic Reticulum Stress; Glucose; Mice; Mitophagy; Neuroprotective Agents; Oxygen; Reperfusion Injury; Signal Transduction; Thapsigargin; Tunicamycin; Ubiquitin-Protein Ligases
PubMed: 25126734
DOI: 10.4161/auto.32136 -
Journal of Experimental & Clinical... Nov 2018Multidrug resistance remains a major obstacle to successful treatment for patients with gastric cancer (GC). Recently, glycosylation has been demonstrated to play a...
BACKGROUND
Multidrug resistance remains a major obstacle to successful treatment for patients with gastric cancer (GC). Recently, glycosylation has been demonstrated to play a vital role in the acquisition of multidrug resistance. As a potent inhibitor of glycosylation, tunicamycin (Tu) has shown marked antitumor activities in various cancers. In the present study, we attempted to determine the exact effect of Tu on the chemoresistance of GC.
METHODS
The cytotoxic effects of drugs on GC cells were evaluated by cell viability assays, and apoptosis was detected by flow cytometry. PCR, western blot analysis, immunofluorescence staining and canonical inhibitors were employed to identify the underlying mechanisms of the specific effects of Tu on multidrug-resistant (MDR) GC cells.
RESULTS
For the first time, we found that MDR GC cells were more sensitive to Tu-induced cell death than the parental cells and that the increased sensitivity might correlate with basal endoplasmic reticulum (ER) stress. In addition, Tu dramatically increased chemotherapy-induced apoptosis by evoking ER stress in GC cells, particularly MDR cells. Further study indicated that these effects were highly dependent on glycosylation inhibition by Tu, rather than its role as a canonical ER stress inducer. Besides, autophagy was markedly triggered by Tu, and blocking autophagy enhanced the combined effects of Tu and chemotherapy on MDR GC cells.
CONCLUSIONS
Our results suggest that tumor-targeted glycosylation inhibition may be a feasible strategy to reverse chemoresistance in GC patients.
Topics: Anti-Bacterial Agents; Apoptosis; Cell Line, Tumor; Drug Resistance, Neoplasm; Endoplasmic Reticulum Stress; Glycosylation; Humans; Stomach Neoplasms; Tunicamycin
PubMed: 30413206
DOI: 10.1186/s13046-018-0935-8 -
Biomolecules Mar 2022Breast cancer is an ancient disease recognized first by the Egyptians as early as 1600 BC. The first cancer-causing gene in a chicken tumor virus was found in 1970. The... (Review)
Review
Breast cancer is an ancient disease recognized first by the Egyptians as early as 1600 BC. The first cancer-causing gene in a chicken tumor virus was found in 1970. The United States signed the National Cancer Act in 1971, authorizing federal funding for cancer research. Irrespective of multi-disciplinary approaches, diverting a great deal of public and private resources, breast cancer remains at the forefront of human diseases, affecting as many as one in eight women during their lifetime. Because of overarching challenges and changes in the breast cancer landscape, five-year disease-free survival is no longer considered adequate. The absence of a cure, and the presence of drug resistance, severe side effects, and destruction of the patient's quality of life, as well as the fact that therapy is often expensive, making it unaffordable to many, have created anxiety among patients, families, and friends. One of the reasons for the failure of cancer therapeutics is that the approaches do not consider cancer holistically. Characteristically, all breast cancer cells and their microenvironmental capillary endothelial cells express asparagine-linked (-linked) glycoproteins with diverse structures. We tested a small biological molecule, Tunicamycin, that blocks a specific step of the protein -glycosylation pathway in the endoplasmic reticulum (ER), i.e., the catalytic activity of -acetylglusosaminyl 1-phosphate transferase (GPT). The outcome was overwhelmingly exciting. Tunicamycin quantitatively inhibits angiogenesis in vitro and in vivo, and inhibits the breast tumor progression of multiple subtypes in pre-clinical mouse models with "zero" toxicity. Mechanistic details support ER stress-induced unfolded protein response () signaling as the cause for the apoptotic death of both cancer and the microvascular endothelial cells. Additionally, it interferes with Wnt signaling. We therefore conclude that Tunicamycin can be expected to supersede the current therapeutics to become a glycotherapy for treating breast cancer of all subtypes.
Topics: Animals; Breast Neoplasms; Endoplasmic Reticulum Stress; Endothelial Cells; Female; Humans; Mice; Quality of Life; Tunicamycin; Unfolded Protein Response
PubMed: 35454076
DOI: 10.3390/biom12040487 -
Molecules and Cells Jun 2023N-glycosylation, a common post-translational modification, is widely acknowledged to have a significant effect on protein stability and folding. N-glycosylation is a... (Review)
Review
N-glycosylation, a common post-translational modification, is widely acknowledged to have a significant effect on protein stability and folding. N-glycosylation is a complex process that occurs in the endoplasmic reticulum (ER) and requires the participation of multiple enzymes. GlcNAc-1-P-transferase (GPT) is essential for initiating N-glycosylation in the ER. Tunicamycin is a natural product that inhibits N-glycosylation and produces ER stress, and thus it is utilized in research. The molecular mechanism by which GPT triggers N-glycosylation is discussed in this review based on the GPT structure. Based on the structure of the GPT-tunicamycin complex, we also discuss how tunicamycin reduces GPT activity, which prevents N-glycosylation. This review will be highly useful for understanding the role of GPT in the N-glycosylation of proteins, as well as presents a potential for considering tunicamycin as an antibiotic treatment.
Topics: Glycosylation; Tunicamycin; Protein Processing, Post-Translational; Endoplasmic Reticulum Stress; Endoplasmic Reticulum
PubMed: 37190766
DOI: 10.14348/molcells.2023.0001 -
Proceedings of the National Academy of... Jul 2021An acute increase in the circulating concentration of glucocorticoid hormones is essential for the survival of severe somatic stresses. Circulating concentrations of...
An acute increase in the circulating concentration of glucocorticoid hormones is essential for the survival of severe somatic stresses. Circulating concentrations of GDF15, a hormone that acts in the brain to reduce food intake, are frequently elevated in stressful states. We now report that GDF15 potently activates the hypothalamic-pituitary-adrenal (HPA) axis in mice and rats. A blocking antibody to the GDNF-family receptor α-like receptor completely prevented the corticosterone response to GDF15 administration. In wild-type mice exposed to a range of stressful stimuli, circulating levels of both corticosterone and GDF15 rose acutely. In the case of or lipopolysaccharide injections, the vigorous proinflammatory cytokine response elicited was sufficient to produce a near-maximal HPA response, regardless of the presence or absence of GDF15. In contrast, the activation of the HPA axis seen in wild-type mice in response to the administration of genotoxic or endoplasmic reticulum toxins, which do not provoke a marked rise in cytokines, was absent in mice. In conclusion, consistent with its proposed role as a sentinel hormone, endogenous GDF15 is required for the activation of the protective HPA response to toxins that do not induce a substantial cytokine response. In the context of efforts to develop GDF15 as an antiobesity therapeutic, these findings identify a biomarker of target engagement and a previously unrecognized pharmacodynamic effect, which will require monitoring in human studies.
Topics: Animals; Cisplatin; Endoplasmic Reticulum Stress; Glial Cell Line-Derived Neurotrophic Factor Receptors; Glucocorticoids; Growth Differentiation Factor 15; Humans; Hypothalamo-Hypophyseal System; Lipopolysaccharides; Mice; Pituitary-Adrenal System; Rats; Tunicamycin
PubMed: 34187898
DOI: 10.1073/pnas.2106868118 -
MBio Aug 2021How cells exposed to one stress are later able to better survive other types of stress is not well understood. In eukaryotic organisms, physiological and pathological...
How cells exposed to one stress are later able to better survive other types of stress is not well understood. In eukaryotic organisms, physiological and pathological stresses can disturb endoplasmic reticulum (ER) function, resulting in "ER stress." Here, we found that exposure to tunicamycin, an inducer of ER stress, resulted in the acquisition of a specific aneuploidy, chromosome 2 trisomy (Chr2x3), in Candida albicans. Importantly, the resulting aneuploidy also conferred cross-tolerance to caspofungin, a first-line echinocandin antifungal, as well as to hydroxyurea, a common chemotherapeutic agent. Exposure to a range of tunicamycin concentrations induced similar ER stress responses. Extra copies of one Chr2 gene, , affected both tunicamycin and caspofungin tolerance, while at least 3 genes on chromosome 2 (, , and ) affected only tunicamycin and not caspofungin responses. Other Chr2 genes ( and ) affected hydroxyurea tolerance but neither tunicamycin nor caspofungin tolerance. Deletion of components of the protein kinase C (PKC) or calcineurin pathways affected tolerance to both tunicamycin and caspofungin, supporting the idea that the ER stress response and echinocandin tolerance are regulated by overlapping stress response pathways. Thus, antifungal drug tolerance can arise rapidly via ER stress-induced aneuploidy. Candida albicans is a prevalent human fungal commensal and also a pathogen that causes life-threatening systemic infections. Treatment failures are frequent because few therapeutic antifungal drug classes are available and because drug resistance and tolerance limit drug efficacy. We found that C. albicans rapidly overcomes the cellular stress induced by the drug tunicamycin by duplicating chromosome 2. Also, chromosome 2 duplication confers tolerance not only to tunicamycin but also to the following two unrelated drugs: caspofungin, an antifungal drug, and hydroxyurea, a chemotherapeutic. Cross tolerance to the three drugs involves different sets of genes, although some genetic pathways affect the tolerance to two of these three drugs. This work highlights a serious concern, namely, that changes in whole chromosome copy number can occur in response to one type of stress, and yet, they may facilitate the emergence of tolerance to multiple drugs, including the few antifungal drug classes available to treat infections.
Topics: Aneuploidy; Antifungal Agents; Candida albicans; Drug Resistance, Fungal; Stress, Physiological; Tunicamycin
PubMed: 34465026
DOI: 10.1128/mBio.02272-21 -
Cell Death & Disease Jul 2021All organisms exposed to metabolic and environmental stresses have developed various stress adaptive strategies to maintain homeostasis. The main bacterial stress...
All organisms exposed to metabolic and environmental stresses have developed various stress adaptive strategies to maintain homeostasis. The main bacterial stress survival mechanism is the stringent response triggered by the accumulation "alarmone" (p)ppGpp, whose level is regulated by RelA and SpoT. While metazoan genomes encode MESH1 (Metazoan SpoT Homolog 1) with ppGpp hydrolase activity, neither ppGpp nor the stringent response is found in metazoa. The deletion of Mesh1 in Drosophila triggers a transcriptional response reminiscent of the bacterial stringent response. However, the function of MESH1 remains unknown until our recent discovery of MESH1 as the first cytosolic NADPH phosphatase that regulates ferroptosis. To further understand whether MESH1 knockdown triggers a similar transcriptional response in mammalian cells, here, we employed RNA-Seq to analyze the transcriptome response to MESH1 knockdown in human cancer cells. We find that MESH1 knockdown induced different genes involving endoplasmic reticulum (ER) stress, especially ATF3, one of the ATF4-regulated genes in the integrative stress responses (ISR). Furthermore, MESH1 knockdown increased ATF4 protein, eIF2a phosphorylation, and induction of ATF3, XBPs, and CHOP mRNA. ATF4 induction contributes to ~30% of the transcriptome induced by MESH1 knockdown. Concurrent ATF4 knockdown re-sensitizes MESH1-depleted RCC4 cells to ferroptosis, suggesting its role in the ferroptosis protection mediated by MESH1 knockdown. ATF3 induction is abolished by the concurrent knockdown of NADK, implicating a role of NADPH accumulation in the integrative stress response. Collectively, these results suggest that MESH1 depletion triggers ER stress and ISR as a part of its overall transcriptome changes to enable stress survival of cancer cells. Therefore, the phenotypic similarity of stress tolerance caused by MESH1 removal and NADPH accumulation is in part achieved by ISR to regulate ferroptosis.
Topics: Activating Transcription Factor 4; Brefeldin A; Cell Cycle; Cell Line; Endoplasmic Reticulum Stress; Ferroptosis; Gene Knockdown Techniques; Humans; Neoplasm Proteins; Phosphorylation; Pyrophosphatases; Stress, Physiological; Transcription, Genetic; Tunicamycin
PubMed: 34294679
DOI: 10.1038/s41419-021-04018-7 -
Microbial Pathogenesis Dec 2020SARS-CoV-2 remains a medical and economic challenge, due to the lack of a suitable drug or vaccine. The glycans in some proteins play a pivotal role in protein folding,... (Review)
Review
SARS-CoV-2 remains a medical and economic challenge, due to the lack of a suitable drug or vaccine. The glycans in some proteins play a pivotal role in protein folding, oligomerization, quality control, sorting, and transport so the hindering of N-linked glycosylation of glycoproteins will prevent assembly of the virion. Tunicamycin an anticancer drug inhibit the N- linked glycans. Our study aimed to find out the mechanism action of tunicamycin on the viral glycoproteins. The growth of coronavirus in the presence inhibitor tunicamycin resulted in the production of spikeless, non-infectious virions which were devoid of S protein. We concluded that tunicamycin inhibits E2, S, and M glycoproteins of coronaviruses. Tunicamycin is also diminished glycosylation of PTMs such as HE, and 8 ab of SARS-CoV. Finally, we recommend using this drug to treat the SARS-CoV-2.
Topics: Animals; COVID-19; Glycosylation; Humans; SARS-CoV-2; Spike Glycoprotein, Coronavirus; Tunicamycin; Viral Matrix Proteins; COVID-19 Drug Treatment
PubMed: 33091582
DOI: 10.1016/j.micpath.2020.104586