Endoplasmic reticulum stress: a novel mechanism and therapeutic target for cardiovascular diseases

Aerobic training attenuates cardiac remodeling in mice post-myocardial infarction by inhibiting the p300/CBP-associated factor

Aerobic training (AT), an effective form of cardiac rehabilitation, has been shown to be beneficial for cardiac repair and remodeling after myocardial infarction (MI). The p300/CBP-associated factor (PCAF) is one of the most important lysine acetyltransferases and is involved in various biological processes. However, the role of PCAF in AT and AT-mediated cardiac remodeling post-MI has not been determined. Here, we found that the PCAF protein level was significantly increased after MI, while AT blocked the increase in PCAF. AT markedly improved cardiac remodeling in mice after MI by reducing endoplasmic reticulum stress (ERS). In vivo, similar to AT, pharmacological inhibition of PCAF by Embelin improved cardiac recovery and attenuated ERS in MI mice. Furthermore, we observed that both IGF-1, a simulated exercise environment, and Embelin protected from H2O2-induced cardiomyocyte injury, while PCAF overexpression by viruses or the sirtuin inhibitor nicotinamide eliminated the protective effect of IGF-1 in H9C2 cells. Thus, our data indicate that maintaining low PCAF levels plays an essential role in AT-mediated cardiac protection, and PCAF inhibition represents a promising therapeutic target for attenuating cardiac remodeling after MI.

Mitochondria- and endoplasmic reticulum-localizing iridium(III) complexes induce immunogenic cell death of 143B cells

Recent breakthroughs in cancer immunology have propelled immunotherapy to the forefront of cancer research as a promising treatment approach that harnesses the body's immune system to effectively identify and eliminate cancer cells. In this study, three novel cyclometalated Ir(III) complexes, Ir1, Ir2, and Ir3, were designed, synthesized, and assessed in vitro for cytotoxic activity against several tumor-derived cell lines. Among these, Ir1 exhibited the highest cytotoxic activity, with an IC50 value of 0.4 ± 0.1 μM showcasing its significant anticancer potential. Detailed mechanistic analysis revealed that co-incubation of Ir1 with 143B cells led to Ir1 accumulation within mitochondria and the endoplasmic reticulum (ER). Furthermore, Ir1 induced G0/G1 phase cell cycle arrest, while also diminishing mitochondrial membrane potential, disrupting mitochondrial function, and triggering ER stress. Intriguingly, in mice the Ir1-induced ER stress response disrupted calcium homeostasis to thereby trigger immunogenic cell death (ICD), which subsequently activated the host antitumor immune response while concurrently dampening the in vivo tumor-induced inflammatory response.

A bibliometric analysis of endoplasmic reticulum stress and atherosclerosis

The mechanisms underlying the occurrence and development of atherosclerosis (AS) are diverse, among which endoplasmic reticulum stress (ERS) is an important mechanism that should not be overlooked. However, up to now, there has been no bibliometric study on the relationship between ERS and AS. To understand the research progress in ERS and AS, this paper conducted a statistical analysis of publications in this field using bibliometrics. A total of 1,035 records were retrieved from the Web of Science Core Collection. CiteSpace, VOSviewer, and the R package "bibliometric" were used to analyze the spatiotemporal distribution, countries, authors, institutions, journals, references, and keywords of the literature, and to present the basic information of this field through visualized maps, as well as determine the collaboration relationships among researchers in this field. This field has gradually developed and stabilized over the past 20 years. The current research hotspots in this field mainly include the relationship between ERS and AS-related cells, the mechanisms by which ERS promotes AS, related diseases, and associated cytokines, etc. Vascular calcification, endothelial dysfunction, NLRP3 inflammasome, and heart failure represent the frontier research in this field and are becoming new research hotspots. It is hoped that this study will provide new insights for research and clinical work in the field of ERS and AS.

H2S alleviates renal ischemia and reperfusion injury by suppressing ERS-induced autophagy

BACKGROUND

Ischemia/reperfusion injury (IRI) can lead to acute kidney injury and result in high disability and mortality rates. Cystathionine γ-lyase (CSE)-produced hydrogen sulfide (H2S) has been confirmed to play a protective role in renal IRI. While autophagy is involved in renal IRI, its role in the regulation by endoplasmic reticulum stress (ERS) has not been considered. Our study explored the role of CSE/H2S in protecting against renal IRI by regulating ERS-induced autophagy.

METHODS

C57/BL6 mice were subjected to 30-min renal ischemia followed by .24-h reperfusion injury (IRI). The H2S donor sodium hydrosulfide hydrate (NaHS) or the CSE inhibitor D,L-propargylglycine (PAG) was injected intraperitoneally (i.p) into the mice. Serum creatinine and urea nitrogen levels were analyzed to evaluate renal function. Renal tubule epithelial cell damage was measured by HE and PAS staining. ERS and microtubule-associated protein light chain 3 (LC3) autophagy (LC3-I to LC3-II conversion) were analyzed by using western blotting.

RESULTS

In a C57/BL6 mouse model of acute renal IRI, the application of IRI impaired the renal function, which was accompanied by elevated serum creatinine (P < 0.001) and urea nitrogen levels (P < 0.001). While NaHS pretreatment dramatically attenuated renal IRI, PAG administration exacerbated renal IRI (P < 0.001). Furthermore, NaHS treatment inhibited the ERS-induced increased LC3II/I protein ratio (P < 0.001); increased Beclin-1 protein expression (P < 0.001); PAG pretreatment exacerbated the effects of ERS on both the LC3II/I ratio (P < 0.001) and the Beclin-1 protein expression (P < 0.001).

CONCLUSIONS

Our results suggest that the CSE/H2S system is an important therapeutic target for protecting against renal IRI, and it may protect renal tubule epithelial cells from IRI by suppressing ERS-induced autophagy.

Effects of gas signaling molecule SO2 in cardiac functions of hyperthyroid rats

Sulfur dioxide (SO2), a novel endogenous gas signaling molecule, is involved in the regulation of cardiac function. Exerting a key role in progression of hyperthyroidism-induced cardiomyopathy (HTC), myocardial fibrosis is mainly caused by myocardial apoptosis, leading to poor treatment outcomes and prognoses. This study aimed to investigate the effect of SO2 on the hyperthyroidism-induced myocardial fibrosis and the underlying regulatory mechanisms. Elisa, Masson staining, Western-Blot, transmission electron microscope, and immunofluorescence were employed to evaluate the myocardial interstitial collagen deposition, endoplasmic reticulum stress (ERS), apoptosis, changes in endogenous SO2, and Hippo pathways from in vitro and in vivo experiments. The study results indicated that the hyperthyroidism-induced myocardial fibrosis was accompanied by decreased cardiac function, and down-regulated ERS, apoptosis, and endogenous SO2-producing enzyme aspartate aminotransferase (AAT)1/2 in cardiac myocytes. In contrast, exogenous SO2 donors improved cardiac function, reduced myocardial interstitial collagen deposition, up-regulated AAT1/2, antagonized ERS and apoptosis, and inhibited excessive activation of Hippo pathway in hyperthyroid rats. In conclusion, the results herein suggested that SO2 inhibited the overactivation of the Hippo pathway, antagonized ERS and apoptosis, and alleviated myocardial fibrosis in hyperthyroid rats. Therefore, this study was expected to identify intervention targets and new strategies for prevention and treatment of HTC.

Exploring the Prospective Role of Propolis in Modifying Aging Hallmarks

Aging populations worldwide are placing age-related diseases at the forefront of the research agenda. The therapeutic potential of natural substances, especially propolis and its components, has led to these products being promising agents for alleviating several cellular and molecular-level changes associated with age-related diseases. With this in mind, scientists have introduced a contextual framework to guide future aging research, called the hallmarks of aging. This framework encompasses various mechanisms including genomic instability, epigenetic changes, mitochondrial dysfunction, inflammation, impaired nutrient sensing, and altered intercellular communication. Propolis, with its rich array of bioactive compounds, functions as a potent functional food, modulating metabolism, gut microbiota, inflammation, and immune response, offering significant health benefits. Studies emphasize propolis' properties, such as antitumor, cardioprotective, and neuroprotective effects, as well as its ability to mitigate inflammation, oxidative stress, DNA damage, and pathogenic gut bacteria growth. This article underscores current scientific evidence supporting propolis' role in controlling molecular and cellular characteristics linked to aging and its hallmarks, hypothesizing its potential in geroscience research. The aim is to discover novel therapeutic strategies to improve health and quality of life in older individuals, addressing existing deficits and perspectives in this research area.

Mzb1 Attenuates Atherosclerotic Plaque Vulnerability in ApoE-/- Mice by Alleviating Apoptosis and Modulating Mitochondrial Function

In this study, we investigated the protective role of Mzb1 in atherosclerotic plaque vulnerability. To explore the impact of Mzb1, we analyzed Mzb1 expression, assessed apoptosis, and evaluated mitochondrial function in atherosclerosis (AS) mouse models and human vascular smooth muscle cells (HVSMCs). We observed a significant decrease in Mzb1 expression in AS mouse models and ox-LDL-treated HVSMCs. Downregulation of Mzb1 increased ox-LDL-induced apoptosis and cholesterol levels of HVSMCs, while Mzb1 overexpression alleviated these effect. Mzb1 was found to enhance mitochondrial function, as evidenced by restored ATP synthesis, mitochondrial membrane potential, and reduced mtROS production. Moreover, Mzb1 overexpression attenuated atherosclerotic plaque vulnerability in ApoE-/- mice. Our findings suggest that Mzb1 overexpression regulates the AMPK/SIRT1 signaling pathway, leading to the attenuation of atherosclerotic plaque vulnerability. This study provides compelling evidence for the protective effect of Mzb1 on atherosclerotic plaques by alleviating apoptosis and modulating mitochondrial function in ApoE-/- mice.

Curcumin alleviates bisphenol AF-induced oxidative stress and apoptosis in caprine endometrial epithelial cells via the Nrf2 signaling pathway

Bisphenol AF (BPAF), a BPA-substitute, has been widely used in industrial compounds throughout the world. Several studies have shown that BPAF has endocrine interference and reproductive toxicity. However, the toxic effects of BPAF on pregnancy and placenta of goats are still unclear. Therefore, the objective of this study was to reveal the toxic effect of BPAF by using an in vitro culture model of caprine endometrial epithelial cells (EECs) and further attempted to alleviate the toxicity by curcumin pretreatment. The results showed that BPAF induces significant effects on EECs, including decreased cell viability and mitochondrial membrane potential (△ψm), elevating intracellular reactive oxygen species (ROS), promoting cell apoptosis through upregulating the expression of Bax, Cytochrome c, and downregulating the expression of Bcl-2. Meanwhile, BPAF induced dysregulation of oxidative stress by increasing the levels of malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) but decreasing the activities of superoxide dismutase (SOD). However, curcumin pretreatment could significantly attenuate BPAF-induced toxic effects in EECs. Further study revealed that BPAF treatment could activate mitogen-activated protein kinase (MAPK) pathway and nuclear factor-erythroid 2-related factor 2 (Nrf2) expression, but curcumin pretreatment significantly inhibited the activation of MAPK signal pathway and Nrf2 expression induced by BPAF. Overall, this study indicated that curcumin could prevent BPAF-induced EECs cytotoxicity, which provides a potential therapeutic strategy for female infertility associated with BPAF exposure.

Molecular mechanisms underlying mitochondrial damage, endoplasmic reticulum stress, and oxidative stress induced by environmental pollutants

Mitochondria and endoplasmic reticulum (ER) are essential organelles playing pivotal roles in the regulation of cellular metabolism, energy production, and protein synthesis. In addition, these organelles are important targets susceptible to external stimuli, such as environmental pollutants. Exposure to environmental pollutants can cause the mitochondrial damage, endoplasmic reticulum stress (ERS), and oxidative stress, leading to cellular dysfunction and death. Therefore, understanding the toxic effects and molecular mechanisms of environmental pollution underlying these processes is crucial for developing effective strategies to mitigate the adverse effects of environmental pollutants on human health. In the present study, we summarized and reviewed the toxic effects and molecular mechanisms of mitochondrial damage, ERS, and oxidative stress caused by exposure to environmental pollutants as well as interactions inducing the cell apoptosis and the roles in exposure to environmental pollutants.

A Probiotic Bacillus amyloliquefaciens D-1 Strain Is Responsible for Zearalenone Detoxifying in Coix Semen

Zearalenone (ZEN) is a mycotoxin produced by Fusarium spp., which commonly and severely contaminate food/feed. ZEN severely affects food/feed safety and reduces economic losses owing to its carcinogenicity, genotoxicity, reproductive toxicity, endocrine effects, and immunotoxicity. To explore efficient methods to detoxify ZEN, we identified and characterized an efficient ZEN-detoxifying microbiota from the culturable microbiome of Pseudostellaria heterophylla rhizosphere soil, designated Bacillus amyloliquefaciens D-1. Its highest ZEN degradation rate reached 96.13% under the optimal condition. And, D-1 can almost completely remove ZEN (90 μg·g-1) from coix semen in 24 h. Then, the D-1 strain can detoxify ZEN to ZEM, which is a new structural metabolite, through hydrolyzation and decarboxylation at the ester group in the lactone ring and amino acid esterification at C2 and C4 hydroxy. Notably, ZEM has reduced the impact on viability, and the damage of cell membrane and nucleus DNA and can significantly decrease the cell apoptosis in the HepG2 cell and TM4 cell. In addition, it was found that the D-1 strain has no adverse effect on the HepG2 and TM4 cells. Our findings can provide an efficient microbial resource and a reliable reference strategy for the biological detoxification of ZEN.

Targeting the adenosine monophosphate-activated protein kinase signalling pathway by bempedoic acid attenuates Angiotensin II-induced cardiac remodelling in renovascular hypertension in rats

The crosstalk between the renin-angiotensin system and Adenosine monophosphate-activated protein kinase (AMPK) gained significant interest due to their involvement in the pathogenesis of several cardiovascular diseases. Angiotensin II (Ang II) plays a crucial role in developing cardiac remodelling by inducing energy imbalance, inflammation, oxidative and endoplasmic reticulum stress, and transforming growth factor-β (TGF-β)-induced fibrosis. Ang II directly or through extracellular signal-regulated kinase (ERK) activation impairs AMPK signalling with well-known antioxidant, anti-inflammatory, and anti-fibrotic effects.

AIM

This study aimed to investigate the role of bempedoic acid, a novel antihyperlipidemic drug, in attenuating hypertension-induced cardiac remodelling in rats by modulating Ang II-induced damage and activating the AMPK signalling pathway.

METHOD

Sixty adult male Sprague Dawley rats were randomly allocated into the Sham control group, Hypertensive group, Captopril group (30 mg/kg), and Bempedoic acid group (30 mg/kg). Hypertension was induced by left renal artery ligation in all groups except the Sham control group. Treatment with captopril and bempedoic acid started 14 days post-surgy and lasted two weeks. Finally, Hemodynamic measurements and electrocardiographic examination were done followed by heart tissue samples collection for biochemical, histopathological, and immunohistochemical examinations.

KEY FINDINGS

Bempedoic acid preserved the cardiac function and electrocardiogram patterns. It inhibited endoplasmic reticulum stress, exhibited antioxidant activity, and increased endothelial nitric oxide synthase activity. Bempedoic acid interfered with ERK signalling pathways, including nuclear factor-κB and TGF-β, exerting anti-inflammatory and anti-fibrotic effects.

SIGNIFICANCE

These findings indicate the cardioprotective and antihypertrophic activity of bempedoic acid, which are suggested to result from energy-independent AMPK downstream signalling activation.

Advances in the interaction between endoplasmic reticulum stress and osteoporosis

The endoplasmic reticulum (ER) is the main site for protein synthesis, folding, and secretion, and accumulation of the unfolded/misfolded proteins in the ER may induce ER stress. ER stress is an important participant in various intracellular signaling pathways. Prolonged- or high-intensity ER stress may induce cell apoptosis. Osteoporosis, characterized by imbalanced bone remodeling, is a global disease caused by many factors, such as ER stress. ER stress stimulates osteoblast apoptosis, increases bone loss, and promotes osteoporosis development. Many factors, such as the drug's adverse effects, metabolic disorders, calcium ion imbalance, bad habits, and aging, have been reported to activate ER stress, resulting in the pathological development of osteoporosis. Increasing evidence shows that ER stress regulates osteogenic differentiation, osteoblast activity, and osteoclast formation and function. Various therapeutic agents have been developed to counteract ER stress and thereby suppress osteoporosis development. Thus, inhibition of ER stress has become a potential target for the therapeutic management of osteoporosis. However, the in-depth understanding of ER stress in the pathogenesis of osteoporosis still needs more effort.

Injectable liposomal docosahexaenoic acid alleviates atherosclerosis progression and enhances plaque stability

Atherosclerosis is a chronic inflammatory vascular disease that is characterized by the accumulation of lipids and immune cells in plaques built up inside artery walls. Docosahexaenoic acid (DHA, 22:6n-3), an omega-3 polyunsaturated fatty acid (PUFA), which exerts anti-inflammatory and antioxidant properties, has long been purported to be of therapeutic benefit to atherosclerosis patients. However, large clinical trials have yielded inconsistent data, likely due to variations in the formulation, dosage, and bioavailability of DHA following oral intake. To fully exploit its potential therapeutic effects, we have developed an injectable liposomal DHA formulation intended for intravenous administration as a plaque-targeted nanomedicine. The liposomal formulation protects DHA against chemical degradation and increases its local concentration within atherosclerotic lesions. Mechanistically, DHA liposomes are readily phagocytosed by activated macrophages, exert potent anti-inflammatory and antioxidant effects, and inhibit foam cell formation. Upon intravenous administration, DHA liposomes accumulate preferentially in atherosclerotic lesional macrophages and promote polarization of macrophages towards an anti-inflammatory M2 phenotype, resulting in attenuation of atherosclerosis progression in both ApoE-/- and Ldlr-/- experimental models. Plaque composition analysis demonstrates that liposomal DHA inhibits macrophage infiltration, reduces lipid deposition, and increases collagen content, thus improving the stability of atherosclerotic plaques against rupture. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) further reveals that DHA liposomes can partly restore the complex lipid profile of the plaques to that of early-stage plaques. In conclusion, DHA liposomes offer a promising approach for applying DHA to stabilize atherosclerotic plaques and attenuate atherosclerosis progression, thereby preventing atherosclerosis-related cardiovascular events.

The beneficial effects of mesenchymal stem cells and their exosomes on myocardial infarction and critical considerations for enhancing their efficacy

Mesenchymal stem cells (MSCs) are multipotent stromal cells with regenerative, anti-inflammatory, and immunomodulatory properties. MSCs and their exosomes significantly improved structural and functional alterations after myocardial infarction (MI) in preclinical studies and clinical trials. By reprograming intracellular signaling pathways, MSCs attenuate inflammatory response, oxidative stress, apoptosis, pyroptosis, and endoplasmic reticulum (ER) stress and improve angiogenesis, mitochondrial biogenesis, and myocardial remodeling after MI. MSC-derived exosomes contain a mixture of non-coding RNAs, growth factors, anti-inflammatory mediators, and anti-fibrotic factors. Although primary results from clinical trials were promising, greater efficacies can be achieved by controlling several modifiable factors. The optimum timing of transplantation, route of administration, origin of MSCs, number of doses, and number of cells per dose need to be further investigated by future studies. Newly, highly effective MSC delivery systems have been developed to improve the efficacy of MSCs and their exosomes. Moreover, MSCs can be more efficacious after being pretreated with non-coding RNAs, growth factors, anti-inflammatory or inflammatory mediators, and hypoxia. Similarly, viral vector-mediated overexpression of particular genes can augment the protective effects of MSCs on MI. Therefore, future clinical trials must consider these advances in preclinical studies to properly reflect the efficacy of MSCs or their exosomes for MI.

Effect of bempedoic acid on angiotensin-II induced hypertension and vascular tissue remodelling in renal hypertensive rats through AMPK multiple signalling pathways modulation

Angiotensin II (Ang II), the effector of the renin-angiotensin system (RAS), is a key player in the pathogenesis of chronic hypertension, accompanied by vascular tissue resistance, remodelling, and damage. Chronic activation of Ang II receptor 1 (AT-1R) impairs multiple cellular targets implicated in cellular protection and survival, including adenosine Monophosphate-activated protein kinase (AMPK) signalling. In addition, it induces oxidative damage, endoplasmic reticulum (ER) stress, and fibrotic changes in resistance vessels. Our study investigated the antihypertensive and antifibrotic effects of bempedoic acid, a first-in-class antihyperlipidemic drug that targets adenosine triphosphate-citrate lyase enzyme to inhibit cholesterol synthesis. We also studied the modulation of multiple AMPK signalling pathways by bempedoic acid in a chronic hypertension model in rats. Sixty male Sprague-Dawley rats were divided into four groups: sham group, hypertensive group, standard captopril group, and bempedoic treated group. All groups underwent left renal artery ligation except the sham group. Fourteen days post-surgery, captopril and bempedoic acid were administered with a dose of 30 mg/kg/day orally to captopril-standard and bempedoic acid-treated groups for two weeks, respectively. In mesenteric resistance arteries, bempedoic acid activated AMPK energy independently and augmented AMPK multiple cellular targets to adapt to Ang II-induced cellular stress. It exerted antioxidant activity, increased endothelial nitric oxide synthase, and reversed the ER stress. Bempedoic acid maintained vascular integrity and prevented vascular remodelling by inhibiting extracellular signal-regulated kinase (ERK)/transforming growth factor-β fibrotic pathway. These effects were reflected in the improved hemodynamic measurements.

Endoplasmic reticulum as a target in cardiovascular diseases: Is there a role for flavonoids?

Flavonoids are found in natural health products and plant-based foods. The flavonoid molecules contain a 15-carbon skeleton with the particular structural construction of subclasses. The most flavonoid's critical subclasses with improved health properties are the catechins or flavonols (e.g., epigallocatechin 3-gallate from green tea), the flavones (e.g., apigenin from celery), the flavanones (e.g., naringenin from citrus), the flavanols (e.g., quercetin glycosides from berries, onion, and apples), the isoflavones (e.g., genistein from soya beans) and the anthocyanins (e.g., cyanidin-3-O-glucoside from berries). Scientific data conclusively demonstrates that frequent intake of efficient amounts of dietary flavonoids decreases chronic inflammation and the chance of oxidative stress expressing the pathogenesis of human diseases like cardiovascular diseases (CVDs). The endoplasmic reticulum (ER) is a critical organelle that plays a role in protein folding, post-transcriptional conversion, and transportation, which plays a critical part in maintaining cell homeostasis. Various stimuli can lead to the creation of unfolded or misfolded proteins in the endoplasmic reticulum and then arise in endoplasmic reticulum stress. Constant endoplasmic reticulum stress triggers unfolded protein response (UPR), which ultimately causes apoptosis. Research has shown that endoplasmic reticulum stress plays a critical part in the pathogenesis of several cardiovascular diseases, including diabetic cardiomyopathy, ischemic heart disease, heart failure, aortic aneurysm, and hypertension. Endoplasmic reticulum stress could be one of the crucial points in treating multiple cardiovascular diseases. In this review, we summarized findings on flavonoids' effects on the endoplasmic reticulum and their role in the prevention and treatment of cardiovascular diseases.

Downhill running induced DNA damage enhances mitochondrial membrane permeability by facilitating ER-mitochondria signaling

To observe whether downhill running can lead to DNA damage in skeletal muscle cells and changes in mitochondrial membrane permeability and to explore whether the DNA damage caused by downhill running can lead to changes in mitochondrial membrane permeability by regulating the components of the endoplasmic reticulum mitochondrial coupling structure (MAM). A total of 48 male adult Sprague-Dawley rats were randomly divided into a control group (C, n = 8) and a motor group (E, n = 40). Rats in Group E were further divided into 0 h (E0), 12 h (E12), 24 h (E24), 48 h (E48) and 72 h (E72) after prescribed exercise, with 8 rats in each group. At each time point, flounder muscle was collected under general anaesthesia. The DNA oxidative damage marker 8-hydroxydeoxyguanosine (8-OHdG) was detected by immunofluorescence. The expression levels of the DNA damage-related protein p53 in the nucleus and the EI24 protein and reep1 protein in whole cells were detected by Western blot. The colocalization coefficients of the endoplasmic reticulum protein EI24 and the mitochondrial protein Vdac2 were determined by immunofluorescence double staining, and the concentration of Ca²⁺ in skeletal muscle mitochondria was detected by a fluorescent probe. Finally, the opening of the mitochondrial membrane permeability transition pore (mPTP) was detected by immunofluorescence. Twelve hours after downhill running, the mitochondrial membrane permeability of the mPTP opened the most (P < 0.05), the content of 8-OHdG in skeletal muscle peaked (P < 0.05), and the levels of the regulatory protein p53, mitochondrial Ca²⁺, and the EI24 and reep1 proteins peaked (P < 0.01). Moreover, the colocalization coefficients of EI24 and Vdac2 and the Mandes coefficients of the two proteins increased first and then recovered 72 h after exercise (P < 0.05). (1) Downhill running can lead to DNA damage in skeletal muscle cells, overload of mitochondrial Ca²⁺ and large opening of membrane permeability transformation pores. (2) The DNA damage caused by downhill running may result in p53 promoting the transcriptional activation of reep1 and EI24, enhancing the interaction between EI24 and Vdac2, and then leading to an increase in Ca²⁺ in skeletal muscle mitochondria and the opening of membrane permeability transition pores.

Atractylenolide III Attenuates Apoptosis in H9c2 Cells by Inhibiting Endoplasmic Reticulum Stress through the GRP78/PERK/CHOP Signaling Pathway

The objective of this study was to determine the effect of atractylenolide III (ATL-III) on endoplasmic reticulum stress (ERS) injury, H9c2 cardiomyocyte apoptosis induced by tunicamycin (TM), and the GRP78/PERK/CHOP signaling pathway. Molecular docking was applied to predict the binding affinity of ATL-III to the key proteins GRP78, PERK, IREα, and ATF6 in ERS. Then, in vitro experiments were used to verify the molecular docking results. ERS injury model of H9c2 cells was established by TM. Cell viability was detected by MTT assay, and apoptosis was detected by Hoechst/PI double staining and flow cytometry. Protein expression levels of GRP78, PERK, eIF2α, ATF4, CHOP, Bax, Bcl-2, and Caspase-3 were detected by Western blot. And mRNA levels of GRP78, CHOP, PERK, eIF2α, and ATF4 were detected by RT-qPCR. Moreover, the mechanism was further studied by using GRP78 inhibitor (4-phenylbutyric acid, 4-PBA), and PERK inhibitor (GSK2656157). The results showed that ATL-III had a good binding affinity with GRP78, and the best binding affinity was with PERK. ATL-III increased the viability of H9c2 cells, decreased the apoptosis rate, downregulated Bax and Caspase-3, and increased Bcl-2 compared with the model group. Moreover, ATL-III downregulated the protein and mRNA levels of GRP78, CHOP, PERK, eIF2α, and ATF4, consistent with the inhibition of 4-PBA. ATL-III also decreased the expression levels of PERK, eIF2α, ATF4, CHOP, Bax, and Caspase-3, while increasing the expression of Bcl-2, which is consistent with GSK2656157. Taken together, ATL-III could inhibit TM-induced ERS injury and H9c2 cardiomyocyte apoptosis by regulating the GRP78/PERK/CHOP signaling pathway and has myocardial protection.

Molecular and cellular mechanisms in diabetic heart failure: Potential therapeutic targets

Diabetes Mellitus (DM) is a worldwide health issue that can lead to a variety of complications. DM is a serious metabolic disorder that causes long-term microvascular and macro-vascular complications, as well as the failure of various organ systems. Diabetes-related cardiovascular diseases (CVD) including heart failure cause significant morbidity and mortality worldwide. Concurrent hypertensive heart disease and/or coronary artery disease have been thought to be the causes of diabetic heart failure in DM patients. However, heart failure is extremely common in DM patients even in the absence of other risk factors such as coronary artery disease and hypertension. The occurrence of diabetes-induced heart failure has recently received a lot of attention. Understanding how diabetes increases the risk of heart failure and how it mediates major cellular and molecular alteration will aid in the development of therapeutics to prevent these changes. Hence, this review aimed to summarize the current knowledge and most recent findings in cellular and molecular mechanisms of diabetes-induced heart failure.

The role of endoplasmic reticulum stress in the pathophysiology of periodontal disease

The endoplasmic reticulum (ER) is a principal organelle for folding, post-translational modifications and transport of secretory, luminal, and membrane proteins. ER stress is a condition induced by the accumulation of unfolded or misfolded proteins owing to a variety of physiological and pathological phenomena. To overcome the deleterious effects of ER stress, unfolded protein response (UPR) is initiated to translocate and remove the misfolded and accumulated proteins. Plenty of evidence shows the correlation between ER stress/UPR and the pathology of inflammatory disease. Periodontal disease is a chronic inflammatory disease characterized by the irreversible destruction of periodontal tissues, which associates with the onset and progress of several systemic diseases. Periodontopathic bacterium and pro-inflammatory mediators play a pivotal role in the progress of periodontal disease. Besides, cigarette smoke has long been associated with periodontal disease. As an inflammatory disorder of the periodontium, periodontal disease is highly related to ER stress. In this review, we provide an overview of the pathophysiological effect of ER stress on periodontal disease through five aspects as follow: ER stress and periodontal tissue remodeling, including both soft tissue and hard tissue; ER stress and the inflammation; ER stress and systematic effect during the periodontal disease; last but not least, ER stress and the autophagic apoptosis in cells.

The cardiotoxicity of asthmatic rats after traffic-related PM2.5 and water-soluble components exposure mediated by endoplasmic reticulum stress and autophagy

Fine particulate matter (PM_2.5) is closely related to cardiopulmonary diseases; it is known that the respiratory system is related to the cardiovascular system. This study aimed to investigate the toxic effects of traffic-related PM_2.5 (TRPM_2.5) and water-soluble components (WSC) on hearts of asthmatic rats and explore potential molecular mechanisms. Here, ovalbumin (OVA)-sensitized asthmatic rats were intratracheally instilled with TRPM_2.5 and WSC every 3 days in total of eight times. Significant myocardial pathological changes were observed in the TRPM_2.5 and WSC group by hematoxylin-eosin (HE) staining. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) results demonstrated TRPM_2.5 and WSC aggravated apoptosis of myocardial cells, which may be triggered by endoplasmic reticulum stress (ERS), as manifested by elevated GRP78, CHOP, and caspase-12. Likewise, TRPM_2.5 and WSC activated autophagy via upregulation of LC3 and p62 gene and protein expression. In conclusion, TRPM_2.5 and WSC may aggravate heart injury in asthmatic rats, possibly through the activation of ERS and autophagy signaling pathway.

Quantitative estimation of intracellular oxidative stress in human tissues

Oxidative stress is known to be involved in and possibly a key driver of the development of numerous chronic diseases, including cancer. It is highly desired to have a capability to reliably estimate the level of intracellular oxidative stress as it can help to identify functional changes and disease phenotypes associated with such a stress, but the problem proves to be very challenging. We present a novel computational model for quantitatively estimating the level of oxidative stress in tissues and cells based on their transcriptomic data. The model consists of (i) three sets of marker genes found to be associated with the production of oxidizing molecules, the activated antioxidation programs and the intracellular stress attributed to oxidation, respectively; (ii) three polynomial functions defined over the expression levels of the three gene sets are developed aimed to capture the total oxidizing power, the activated antioxidation capacity and the oxidative stress level, respectively, with their detailed parameters estimated by solving an optimization problem and (iii) the optimization problem is so formulated to capture the relevant known insights such as the oxidative stress level generally goes up from normal to chronic diseases and then to cancer tissues. Systematic assessments on independent datasets indicate that the trained predictor is highly reliable and numerous insights are made based on its application results to samples in the TCGA, GTEx and GEO databases.

Implications of enigmatic transglutaminase 2 (TG2) in cardiac diseases and therapeutic developments

Cardiac diseases are the leading cause of mortality and morbidity worldwide. Mounting evidence suggests that transglutaminases (TGs), tissue TG (TG2) in particular, are involved in numerous molecular responses underlying the pathogenesis of cardiac diseases. The TG family has several intra- and extracellular functions in the human body, including collagen cross-linking, angiogenesis, cell growth, differentiation, migration, adhesion as well as survival. TGs are thiol- and calcium-dependent acyl transferases that catalyze the formation of a covalent bond between the γ-carboxamide group of a glutamine residue and an amine group, thus increasing the stability, rigidity, and stiffness of the myocardial extracellular matrix (ECM). Excessive accumulation of cross-linked collagen leads to increase myocardial stiffness and fibrosis. Beyond TG2 extracellular protein cross-linking action, mounting evidence suggests that this pleiotropic TG isozyme may also promote fibrotic diseases through cell survival and profibrotic pathway activation at the signaling, transcriptional and translational levels. Due to its multiple functions and localizations, TG2 fulfils critical yet incompletely understood roles in myocardial fibrosis and associated heart diseases, such as cardiac hypertrophy, heart failure, and age-related myocardial stiffness under several conditions. This review summarizes current knowledge and existing gaps regarding the ECM-dependent and ECM-independent roles of TG2 and highlights the therapeutic prospects of targeting TG2 to treat cardiac diseases.

Heterozygote Advantage of the Type II Deiodinase Thr92Ala Polymorphism on Intrahospital Mortality of COVID-19

CONTEXT

The type 2 deiodinase and its Thr92Ala-DIO2 polymorphism have been linked to clinical outcomes in acute lung injury and pulmonary fibrosis.

OBJECTIVE

Our objectives were to evaluate were cumulative mortality during admission according to Thr92Ala-DIO2 polymorphism.

METHODS

Here we conducted an observational, longitudinal, and prospective cohort study to investigate a possible association between the Thr92Ala-DIO2 polymorphism and intrahospital mortality from COVID-19 in adult patients admitted between June and August 2020. Blood biochemistry, thyroid function tests, length of stay, comorbidities, complications, and severity scores were also studied according to Thr92Ala-DIO2 polymorphism.

RESULTS

In total, 220 consecutive patients (median age 62; 48-74 years) were stratified into 3 subgroups: Thr/Thr (n = 79), Thr/Ala (n = 119), and Ala/Ala (n = 23). While the overall mortality was 17.3%, the lethality was lower in Ala/Thr patients (12.6%) than in Thr/Thr patients (21.7%) or Ala/Ala patients (23%). The heterozygous genotype (Thr/Ala) was associated with a 47% reduced risk of intrahospital mortality whereas univariate and multivariate logistic regression adjusted for multiple covariates revealed a reduction that ranged from 51% to 66%. The association of the Thr/Ala genotype with better clinical outcomes was confirmed in a metanalysis of 5 studies, including the present one.

CONCLUSION

Here we provide evidence for a protective role played by Thr92Ala-DIO2 heterozygosity in patients with COVID-19. This protective effect follows an inheritance model known as overdominance, in which the phenotype of the heterozygote lies outside the phenotypical range of both homozygous.

Putative therapeutic impacts of cardiac CTRP9 in ischaemia/reperfusion injury

Recently, cytokines belonging to C1q/tumour necrosis factor‐related proteins (CTRPs) superfamily have attracted increasing attention due to multiple metabolic functions and desirable anti‐inflammatory effects. These various molecular effectors exhibit key roles upon the onset of cardiovascular diseases, making them novel adipo/cardiokines. This review article aimed to highlight recent findings correlated with therapeutic effects and additional mechanisms specific to the CTRP9, particularly in cardiac ischaemia/reperfusion injury (IRI). Besides, the network of the CTPR9 signalling pathway and its possible relationship with IRI were discussed. Together, the discovery of all involved underlying mechanisms could shed light to alleviate the pathological sequelae after the occurrence of IRI.

APJ/apelin: a promising target for the treatment of retinopathy of prematurity

Retinopathy of prematurity is a noticeable retinal abnormality causing common blindness in children. An uncontrolled retinal vasculature in retinopathy of prematurity inflicts vision loss in numerous children despite the accessibility to a wide range of clinical treatments prescribed for retinopathy of prematurity. Apelin/APJ [class A (rhodopsin-like) G-protein-coupled receptor] signaling regulates retinopathy of prematurity augmented with uncontrolled angiogenesis. Antagonists targeting pathological apelin/APJ-signaling-induced angiogenesis could be effective in attenuating retinopathy of prematurity. The therapeutic proficiency of antagonists in diverse modalities: peptides, bioactive molecules and antibodies, targeting apelin peptides or the APJ receptor is discussed in this review. We hypothesize the antagonists could effectively attenuate the retinal vasculature triggered by apelin/APJ signaling activation governing vision impairment in young children.

Luteolin alleviates cognitive impairment in Alzheimer's disease mouse model via inhibiting endoplasmic reticulum stress-dependent neuroinflammation

Luteolin is a flavonoid in a variety of fruits, vegetables, and herbs, which has shown anti-inflammatory, antioxidant, and anti-cancer neuroprotective activities. In this study, we investigated the potential beneficial effects of luteolin on memory deficits and neuroinflammation in a triple-transgenic mouse model of Alzheimer's disease (AD) (3 × Tg-AD). The mice were treated with luteolin (20, 40 mg · kg^-1 · d^-1, ip) for 3 weeks. We showed that luteolin treatment dose-dependently improved spatial learning, ameliorated memory deficits in 3 × Tg-AD mice, accompanied by inhibiting astrocyte overactivation (GFAP) and neuroinflammation (TNF-α, IL-1β, IL-6, NO, COX-2, and iNOS protein), and decreasing the expression of endoplasmic reticulum (ER) stress markers GRP78 and IRE1α in brain tissues. In rat C6 glioma cells, treatment with luteolin (1, 10 µM) dose-dependently inhibited LPS-induced cell proliferation, excessive release of inflammatory cytokines, and increase of ER stress marker GRP78. In conclusion, luteolin is an effective agent in the treatment of learning and memory deficits in 3 × Tg-AD mice, which may be attributable to the inhibition of ER stress in astrocytes and subsequent neuroinflammation. These results provide the experimental basis for further research and development of luteolin as a therapeutic agent for AD.

Autophagy, Oxidative Stress and Cancer Development

Simple Summary

Autophagy, as an important cellular repair mechanism, is important for the prevention of several diseases, including metabolic and neurologic disorders, and cancer. Hence, dysfunctional autophagy has been linked to these diseases, and in recent years researchers have tried to outline therapeutic targets in autophagy-related pathways as a treatment. With this review of the literature, we want to give an overview about the connection between oxidative stress, autophagy and cancer.

Abstract

Autophagy is an important cellular repair mechanism, aiming at sequestering misfolded and dysfunctional proteins and damaged cell organelles. Dysfunctions in the autophagy process have been linked to several diseases, like infectious and neurodegenerative diseases, type II diabetes mellitus and cancer. Living organisms are constantly subjected to some degree of oxidative stress, mainly induced by reactive oxygen and nitrogen species. It has been shown that autophagy is readily induced by reactive oxygen species (ROS) upon nutrient deprivation. In recent years, research has increasingly focused on outlining novel therapeutic targets related to the autophagy process. With this review of the literature, we want to give an overview about the link between autophagy, oxidative stress and carcinogenesis.

Preventive Effect of Apple Polyphenol Extract on High-Fat Diet-Induced Hepatic Steatosis in Mice through Alleviating Endoplasmic Reticulum Stress

In this work, the protective effect of apple polyphenol extract (APE) on hepatic steatosis was investigated. Thirty-two C57BL/6J mice were assigned randomly to control group, hepatic steatosis group, lovastatin group, and APE group. After 8 weeks of intervention, APE supplementation markedly decreased the body weight gain, liver weight, liver index, epididymal adipose weight, epididymal adipose index, serum, and hepatic lipid levels. Hematoxylin and eosin staining revealed that APE supplementation alleviated histopathological changes of hepatic steatosis. Western blot revealed that APE downregulated the protein levels of GRP78, IRE1α, p-IRE1α, XBP1, PERK, p-PERK, p-eIF2α, ATF6, PPAR-γ, SREBP-1c, FAS, and ACC1. In conclusion, this study found that APE inhibited IRE1α-XBP1, PERK-eIF2α, and ATF6 signaling pathways to alleviate endoplasmic reticulum stress, thereby improving HFD-induced hepatic steatosis.

Recent progress in small-molecule fluorescent probes for endoplasmic reticulum imaging in biological systems

Endoplasmic reticulum (ER) is an indispensable organelle in eukaryotic cells involved in protein synthesis and processing, as well as calcium storage and release. Therefore, maintaining the quality of ER is of great importance for cellular homeostasis. Aberrant fluctuations of bioactive species in the ER will result in homeostasis disequilibrium and further cause ER stress, which has evolved to contribute to the pathogenesis of various diseases. Therefore, the real-time monitoring of various bioactive species in the ER is of high priority to ascertain the mysterious roles of ER, which will contribute to unveiling the corresponding mechanism of organism disturbances. Recently, fluorescence imaging has emerged as a robust technique for the direct visualization of molecular events due to its outstanding sensitivity, high temporal-spatial resolution and noninvasive nature. In this review, we comprehensively summarize the recent progress in design strategies, bioimaging applications, potential directions and challenges of ER-targetable small-molecular fluorescent probes.

A high-concentrate diet provokes inflammation, endoplasmic reticulum stress, and apoptosis in mammary tissue of dairy cows through the upregulation of STIM1/ORAI1

High-concentrate feeding can induce subacute ruminal acidosis, which leads to mammary tissue injury in dairy cows. Therefore, the purpose of this research was to evaluate the effect of high-concentrate feeding on STIM1 (stromal interaction molecule 1)/ORAI1 (Orai calcium release-activated calcium modulator 1)-mediated inflammation, endoplasmic reticulum stress (ERS), and apoptosis in the mammary tissue of dairy cows. A total of 12 healthy mid-lactating Holstein cows of similar weight were randomly allotted into the following 2 groups: a high-concentrate (HC) group (concentrate:forage = 6:4) and a low-concentrate (LC) group (concentrate:forage = 4:6). The trial lasted for 3 wk. After the feeding experiment, rumen fluid, lacteal vein blood, and mammary tissue samples were collected. The results showed that the HC diet significantly increased blood lipopolysaccharide levels, decreased ruminal pH, and upregulated the concentrations of Ca²⁺ and proinflammatory cytokines, including TNF-α, IL-1β, and IL-6, and the enzyme activities of caspase-3, caspase-9, PKC, and IKK. The upregulation of STIM1, ORAI1, PKCα, IKKβ, phosphorylated-IκBα, phosphorylated-p65, TNF-α, and IL-1α proteins in the HC group indicated activation of the STIM1/ORAI1-mediated inflammatory signaling pathway compared with that in the LC group. The HC diet also induced ERS by increasing the mRNA and protein abundances of GRP78, CHOP, PERK, ATF6, and IRE1α in the mammary tissue. Compared with the LC group, the mRNA expression levels and protein abundances of caspase-3, cleaved caspase-3, caspase-9, and BAX were markedly increased in the HC group. However, the mRNA and protein expression levels of Bcl-2 were significantly decreased in the HC group. Therefore, this study demonstrated that the HC diet can activate the store-operated calcium entry channel by upregulating the expression of STIM1 and ORAI1 and induce inflammation, ERS, and apoptosis in the mammary tissue of dairy cows.

Chinese Herbal Medicine Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating Endoplasmic Reticulum Stress

Myocardial ischemia/reperfusion injury is the main cause of increased mortality and disability in cardiovascular diseases. The injury involves many pathological processes, such as oxidative stress, calcium homeostasis imbalance, inflammation, and energy metabolism disorders, and these pathological stimuli can activate endoplasmic reticulum stress. In the early stage of ischemia, endoplasmic reticulum stress alleviates the injury as an adaptive survival response, but the long-term stress on endoplasmic reticulum amplifies oxidative stress, inflammation, and calcium overload to accelerate cell damage and apoptosis. Therefore, regulation of endoplasmic reticulum stress may be a mechanism to improve ischemia/reperfusion injury. Chinese herbal medicine has a long history of clinical application and unique advantages in the treatment of ischemic heart diseases. This review focuses on the effect of Chinese herbal medicine on myocardial ischemia/reperfusion injury from the perspective of regulation of endoplasmic reticulum stress.

Contribution of Endoplasmic Reticulum Stress to the Clinical Instability of Carotid Plaques in Human Carotid Stenosis

Endoplasmic reticulum (ER) stress is an important process during the progression of atherosclerosis. The aim of this study was to elucidate the association of ER stress and clinical instability of carotid plaque. One hundred ninety-three patients with carotid stenosis undergoing carotid endarterectomies (CEAs) were enrolled. We classified the patients into 3 groups: the asymptomatic, symptomatic, and cTIA (crescendo transient ischemic attack)/SIE (stroke in evolution) groups. Immunohistological staining was performed to assess ER stress and apoptosis. The correlation between ER stress marker expression and clinical instability was analyzed by Tukey-Kramer test and ordinal logistic regression. From the 193 CEAs, 24 asymptomatic plaques and 24 symptomatic plaques were randomly selected, and all 7 plaques in the cTIA/SIE group were selected. Glycophorin A staining demonstrated significant correlation between intraplaque hemorrhage and clinical instability (odds ratio [OR], 1.27; 95%CI, 1.14-1.41). The expression of ER stress markers (glucose-regulated protein 78 [GRP78] and C/EBP homologous protein [CHOP]) exhibited a significant correlation with clinical instability (GRP78: OR, 1.25; 95%CI, 1.14-1.38, CHOP: OR, 1.39; 95%CI, 1.16-1.66). Double-label immunofluorescence demonstrated ER stress markers were detected in CD68-positive cells and smooth muscle actin (SMA)-positive cells. The coexpression of the ER stress markers exhibited a significant correlation with clinical instability (CD68/GRP78: OR, 1.13; 95%CI, 1.05-1.20, CD68/CHOP: OR, 1.092; 95%CI, 1.04-1.14, SMA/CHOP: OR, 1.082; 95%CI, 1.04-1.13). However, the colocalization of CHOP and cleaved caspase-3 (apoptosis marker) did not correlate with clinical instability. These findings indicated that the ER stress pathway may be a potential therapeutic target in the prevention of stroke.

Wenxin Granules Regulate Endoplasmic Reticulum Stress Unfolded Protein Response and Improve Ventricular Remodeling on Rats with Myocardial Infarction

Background. Arrhythmia after myocardial infarction is the leading cause of death in clinical heart disease. Increasing studies have shown that the response to endoplasmic reticulum (ER) stress (ERS) caused by myocardial infarction is related to prognosis and the development of arrhythmias. The unfolded protein response (UPR) could serve as an important regulatory signaling pathway following myocardial infarction. The traditional Chinese medicine Wenxin Granules improve arrhythmias following myocardial infarction, which may be related to ERS intervention and the activation of the UPR and apoptosis. We aimed to investigate the involvement of Wenxin Granules in the activation of the UPR and apoptosis following myocardial infarction. Left coronary artery ligation was established as a rat model of myocardial infarction. The rats were randomly divided into the model group, low-dose Wenxin Granule group, high-dose Wenxin Granule group, and metoprolol group. Rats with only wire insertion and no ligature were used as the sham group. Small animal ultrasound systems were used to detect changes in heart structure and function, and the electrical stimulation threshold for ventricular fibrillation was detected. The expression of glucose-regulated protein (GRP)78, activating transcription factor (ATF)6, X-box binding protein (XBP)1, protein kinase-like ER kinase (PERK), phosphorylated (p)-PERK, Bax, Bcl2, C/EBP homologous protein (CHOP), caspase 12, caspase 8, and caspase 3 were detected by western blot, and terminal deoxynucleotidyl transferase dUTP Nick end labeling (TUNEL) was used to determine the cardiomyocyte apoptosis index. Compared with the sham group, rats in the model group displayed immediate ST-segment elevation and pathological Q waves after 24 hours. After 2 weeks, the left ventricular (LV) anterior wall thickness (LVAW) became thinner, and the inner diameter (LVID) increased. The end-diastolic LVAW (LVAWd), end-systolic LVAW (LVAWs), ejection fraction (EF), and fractional shortening (FS) were significantly reduced (P < 0.01), whereas the LVIDd, LVIDs, diastolic LV volume (LV Vold), and systolic LV volume (LV Vols) significantly increased (P < 0.01). The ventricular fibrillation threshold decreased significantly (P < 0.01). ERS proteins GRP78, p-PERK, PERK, ATF6, and XBP1 and apoptotic proteins CHOP, Bax, caspase 12, caspase 8, and caspase 3 significantly increased (P < 0.01, P < 0.05), whereas Bcl-2 expression and the Bcl-2/Bax ratio decreased (P < 0.01). Compared with the sham group, LVAWd, LVAWs, FS, and Bcl-2 protein expression were significantly increased in the low-dose Wenxin Granule group (P < 0.01, P < 0.05), and p-PERK and ATF6 decreased (P < 0.01, P < 0.05). Compared with the sham group, LVAWd, LVAWs, EF, FS, and the ventricular fibrillation threshold significantly increased in the high-dose Wenxin Granule and metoprolol groups (P < 0.01, P < 0.05), whereas LVIDs, LV Vols, and ERS proteins were significantly decreased (P < 0.01, P < 0.05). CHOP, Bax, caspase 12, caspase 8, and caspase 3 protein expression decreased in the Wenxin Granule group (P < 0.01, P < 0.05), whereas Bcl-2 and the Bcl-2/Bax ratio increased (P < 0.01, P < 0.05). LVIDd and Bax decreased in the metoprolol group (P < 0.01, P < 0.05), and the Bcl-2/Bax ratio increased (P < 0.05). The cardiomyocyte apoptosis index values for the low- and high-dose Wenxin Granule and metoprolol groups were significantly reduced (P < 0.05). This study suggested that the UPR is an essential mechanism underlying pathological injury after myocardial infarction. Wenxin Granule treatment can improve ventricular remodeling and cardiac function and inhibit arrhythmia by preventing excessive ERS from activating the UPR and apoptosis.

Asaronic acid inhibits ER stress sensors and boosts functionality of ubiquitin-proteasomal degradation in 7β-hydroxycholesterol-loaded macrophages

BACKGROUND

Misfolded proteins are formed in the endoplasmic reticulum (ER) due to diverse stimuli including oxidant production, calcium disturbance, and inflammatory factors. Accumulation of these non-native proteins in the ER evokes cellular stress involving the activation of unfolded protein response (UPR) and the execution of ER-associated degradation (ERAD). Naturally-occurring plant compounds are known to interfere with UPR due to their antioxidant and anti-inflammatory activities, leading to inhibition of ER stress. However, there are few studies dealing with the protective effects of natural compounds on the functionality of ERAD.

PURPOSE

The current study examined whether asaronic acid enhanced ubiquitin-proteasomal degradation in J774A.1 murine macrophages exposed to 7β-hydroxycholesterol, a risk factor for atherosclerosis. Asaronic acid (2,4,5-trimethoxybenzoic acid), identified as one of purple perilla constituents, has anti-diabetic and anti-inflammatory effects. Little is known regarding the effects of asaronic acid on the ERAD process and the ubiquitin-proteasomal degradation.

METHODS AND RESULTS

Murine macrophages were incubated with 28 μM 7β-hydroxycholesterol in absence and presence of 1-20 μΜ asaronic acid for up to 24 h. Nontoxic asaronic acid in macrophage diminished the activation of the ER stress sensors of ATF6, IRE1 and PERK stimulated by 7β-hydroxycholesterol. This methoxybenzoic acid down-regulated the oxysterol-induced expression of EDEM1, OS9, Sel1L-Hrd1 and p97/VCP1, all required for the recognition, recruitment and dislocation of misfolded proteins. On the other hand, asaronic acid enhanced the ubiquitin-proteasomal degradation of non-native proteins dislocated to the cytosol by 7β-hydroxycholesterol, which entailed the induction of the chaperones of Hsp70 and CHIP and the increased colocalization of ubiquitin and proteasomes. Taken together, asaronic acid attenuated the induction of the UPR-associated sensors and the dislocation-linked transmembrane components in the ER. Conversely, this compound enhanced the proteasomal degradation of dislocated non-native proteins in concert with the chaperones of Hsp70 and CHIP through ubiquitination.

CONCLUSION

These observations demonstrate that asaronic acid may be a potent atheroprotective agent as a natural chaperone targeting ER stress-associated macrophage injury.

Visualization of Dynamic Expression of Myocardial Sigma-1 Receptor After Myocardial Ischemia and Reperfusion Using Radioiodine-Labeled 2-[4-(2-iodophenyl)piperidino]cyclopentanol (OI5V) Imaging

BACKGROUND

This study chronologically evaluated the expression of the intensity and distribution of the sigma-1 receptor (σ1R) demonstrated by radiolabeled 2-[4-(2-iodophenyl)piperidino]cyclopentanol (OI5V) in a rat model of myocardial ischemia and reperfusion.Methods and Results:The left coronary artery was occluded for 30 min, followed by reperfusion. Dual-tracer autoradiography with 125I-OI5V and 99 mTc-MIBI was performed to assess the spatiotemporal changes in 125I-OI5V uptake (n=5-6). Significant and peaked 125I-OI5V uptake in the ischemic area was observed at 3 days after reperfusion, and the 125I-OI5V uptake ratio of ischemic area to normally perfused left ventricular area decreased gradually from 3 to 28 days (mean value±SD; 0.90±0.12 at 1 day, 1.89±0.19 at 3 days, 1.52±0.17 at 7 days, 1.34±0.13 at 14 days, and 1.16±0.14 at 28 days, respectively). Triple-tracer autoradiography with 125I-OI5V, 99 mTc-MIBI, and 201TlCl was performed to evaluate 125I-OI5V uptake in the ischemic area in relation to the residual perfusion at 7 days (n=4). The 125I-OI5V uptake ratio of the non-salvaged area was higher compared to that of the salvaged area in the ischemic area. 123I-OI5V and 99 mTc-MIBI SPECT/CT was performed 3 days after reperfusion (n=3), and the in vivo images showed clear uptake of 123I-OI5V in the perfusion defect area.

CONCLUSIONS

The present study confirmed the spatiotemporal expression pattern of σ1R expression. Non-invasive σ1R imaging with 123I or 125I-OI5V was feasible to monitor the expression of σ1R after myocardial ischemia and reperfusion.

Effect of endoplasmic reticulum stress-induced apoptosis in the role of periodontitis on vascular calcification in a rat model

The present study aimed to investigate the mechanism(s) through which endoplasmic reticulum stress (ERS)-induced apoptosis, in the role of periodontitis, affects vascular calcification. Rat models of periodontitis, vascular calcification, periodontitis-vascular calcification, and a normal group were established. Cardiovascular tissues were obtained, and hematoxylin-eosin staining was applied to demonstrate the morphological changes in vascular tissues. Immunohistochemical staining was applied to analyze apoptosis in cardiovascular tissues. The expression levels of apoptotic factor cysteinyl aspartate specific proteinase 3 (Caspase-3), ERS-induced apoptotic factors glucose-regulated protein 78 (GRP78), 94 (GRP94), and ERS-induced apoptosis pathways Caspase-12, C/EBP homologous protein (CHOP), and c-Jun N-terminal kinase (JNK) were analyzed and compared. Hematoxylin-eosin staining revealed that the arterial layers in the normal group were structurally intact. The structural damage to the aortic wall gradually aggravated from the periodontitis group to the vascular calcification group to the combined group. The immunohistochemistry results showed Caspase-3, GRP78, GRP94, and ERS-induced apoptosis pathways in the cardiovascular tissues cells in the periodontitis group, vascular calcification group, and combined group. The Caspase-3, GRP78, GRP94, and CHOP expression levels in the combined group were significantly higher than that in the normal group (P < 0.05); however, the Capase-12 and JNK expression levels in the four groups exhibited no significant differences (P > 0.05). Apoptosis induced by ERS is involved in the effect of periodontitis on vascular calcification and might be mainly achieved through the activation of the CHOP transcription pathway.

Demethylzeylasteral (T-96) initiates extrinsic apoptosis against prostate cancer cells by inducing ROS-mediated ER stress and suppressing autophagic flux

Background

Demethylzeylasteral (T-96) is a pharmacologically active triterpenoid monomer extracted from Tripterygium wilfordii Hook F (TWHF) that has been reported to exhibit anti-neoplastic effects against several types of cancer cells. However, the potential anti-tumour effects of T-96 against human Prostate cancer (CaP) cells and the possible underlying mechanisms have not been well studied.

Results

In the current study, T-96 exerted significant cytotoxicity to CaP cells in vitro and induced cell cycle arrest at S-phase in a dose-dependent manner. Mechanistically, T-96 promoted the initiation of autophagy but inhibited autophagic flux by inducing ROS-mediated endoplasmic reticulum (ER) stress which subsequently activated the extrinsic apoptosis pathway in CaP cells. These findings implied that T-96-induced ER stress activated the caspase-dependent apoptosis pathway to inhibit proliferation of CaP cells. Moreover, we observed that T-96 enhances the sensitivity of CaP cells to the chemotherapeutic drug, cisplatin.

Conclusions

Taken together, our data demonstrated that T-96 is a novel modulator of ER stress and autophagy, and has potential therapeutic applications against CaP in the clinic.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00350-6.

Inhibition of Calpain Alleviates Apoptosis in Coxsackievirus B3-induced Acute Virus Myocarditis Through Suppressing Endoplasmic Reticulum Stress

Virus myocarditis (VMC) is a common cardiovascular disease and a major cause of sudden death in young adults. However, there is still a lack of effective treatments. Our previous studies found that calpain activation was involved in VMC pathogenesis. This study aims to explore the underlying mechanisms further. Neonatal rat cardiomyocytes (NRCMs) and transgenic mice overexpressing calpastatin (Tg-CAST), the endogenous calpain inhibitor, were used to establish VMC model. Hematoxylin and eosin and Masson staining revealed inflammatory cell infiltration and fibrosis. An ELISA array detected myocardial injury. Cardiac function was measured using echocardiography. CVB3 replication was assessed by capsid protein VP1. Apoptosis was measured by TUNEL staining, flow cytometry, and western blot. The endoplasmic reticulum (ER) stress-related proteins were detected by western blot. Our data showed that CVB3 infection resulted in cardiac injury, as evidenced by increased inflammatory responses and fibrosis, which induced myocardial apoptosis. Inhibiting calpain, both by PD150606 and calpastatin overexpression, could attenuate these effects. Furthermore, ER stress was activated during CVB3 infection. However, calpain inhibition could downregulate some ER stress-associated protein levels such as GRP78, pancreatic ER kinase-like ER kinase (PERK), and inositol-requiring enzyme-1α (IRE-1α), and ER stress-related apoptotic factors, during CVB3 infection. In conclusion, calpain inhibition attenuated CVB3-induced myocarditis by suppressing ER stress, thereby inhibiting cardiomyocyte apoptosis.

Triple Negative Breast Cancer: A Mountain Yet to Be Scaled Despite the Triumphs

Metastatic progression and tumor recurrence pertaining to TNBC are certainly the leading cause of breast cancer-related mortality; however, the mechanisms underlying TNBC chemoresistance, metastasis, and tumor relapse remain somewhat ambiguous. TNBCs show 77% of the overall 4-year survival rate compared to other breast cancer subtypes (82.7 to 92.5%). TNBC is the most aggressive subtype of breast cancer, with chemotherapy being the major approved treatment strategy. Activation of ABC transporters and DNA damage response genes alongside an enrichment of cancer stem cells and metabolic reprogramming upon chemotherapy contribute to the selection of chemoresistant cells, majorly responsible for the failure of anti-chemotherapeutic regime. These selected chemoresistant cells further lead to distant metastasis and tumor relapse. The present review discusses the approved standard of care and targetable molecular mechanisms in chemoresistance and provides a comprehensive update regarding the recent advances in TNBC management.

Glucocorticoids protect HEI-OC1 cells from tunicamycin-induced cell damage via inhibiting endoplasmic reticulum stress

Background

To analyze mechanisms of action of glucocorticoid treatment for endoplasmic reticulum stress (ERS) in sensorineural hearing loss (SNHL), we aimed to evaluate the expression and activation status of the protein kinase RNA-like ER kinase (PERK)–C/EBP homologous protein (CHOP) pathway, which is the major pathway in the ERS.

Methods

In the present study, we established an in vitro ERS model using tunicamycin-treated hair-cell-like HEI-OC1 cells. The effect of dexamethasone on proliferation inhibition, apoptosis, and ATF4–CHOP pathway in HEI-OC1 cells was examined by CCK-8 assay, flow cytometry, western blotting, and reverse transcription PCR, respectively.

Results

In HEI-OC1 cells, dexamethasone was shown to significantly reduce the tunicamycin-induced expression of ATF4 and CHOP in the context of sustained viability and proliferation, a therapeutic effect that was reversible by co-treatment with a glucocorticoid antagonist.

Conclusion

Dexamethasone can protect hair-cell-like HEI-OC1 cells from ERS damage, which may be one of the mechanisms of action for GCs in SNHL treatment.

Electroacupuncture Pretreatment Mitigates Myocardial Ischemia/Reperfusion Injury via XBP1/GRP78/Akt Pathway

Myocardial ischemia/reperfusion injury is a common clinical problem and can result in severe cardiac dysfunction. Previous studies have demonstrated the protection of electroacupuncture against myocardial ischemia/reperfusion injury. However, the role of X-box binding protein I (XBP1) signaling pathway in the protection of electroacupuncture was still elusive. Thus, we designed this study and demonstrated that electroacupuncture significantly improved cardiac function during myocardial ischemia/reperfusion injury and reduced cardiac infarct size. Electroacupuncture treatment further inhibited cardiac injury manifested by the decrease of the activities of serum lactate dehydrogenase and creatine kinase-MB. The results also revealed that electroacupuncture elevated the expressions of XBP1, glucose-regulated protein 78 (GRP78), Akt, and Bcl-2 and decreased the Bax and cleaved Caspase 3 expressions. By using the inhibitor of XBP1 in vitro, the results revealed that suppression of XBP1 expression could markedly increase the activities of lactate dehydrogenase and creatine kinase-MB and cell apoptosis, thus exacerbating stimulated ischemia/reperfusion-induced H9c2 cell injury. Compared with stimulated ischemia/reperfusion group, inhibition of XBP1 inhibited the downstream GRP78 and Akt expressions during stimulated ischemia/reperfusion injury. Collectively, our data demonstrated that electroacupuncture treatment activated XBP1/GRP78/Akt signaling to protect hearts from myocardial ischemia/reperfusion injury. These findings revealed the underlying mechanisms of electroacupuncture protection against myocardial ischemia/reperfusion injury and may provide novel therapeutic targets for the clinical treatment of myocardial ischemia/reperfusion injury.

Phosphoproteomic response of cardiac endothelial cells to ischemia and ultrasound

Myocardial infarction and subsequent therapeutic interventions activate numerous intracellular cascades in every constituent cell type of the heart. Endothelial cells produce several protective compounds in response to therapeutic ultrasound, under both normoxic and ischemic conditions. How endothelial cells sense ultrasound and convert it to a beneficial biological response is not known. We adopted a global, unbiased phosphoproteomics approach aimed at understanding how endothelial cells respond to ultrasound. Here, we use primary cardiac endothelial cells to explore the cellular signaling events underlying the response to ischemia-like cellular injury and ultrasound exposure in vitro. Enriched phosphopeptides were analyzed with a high mass accuracy liquid chromatrography (LC) - tandem mass spectrometry (MS/MS) proteomic platform, yielding multiple alterations in both total protein levels and phosphorylation events in response to ischemic injury and ultrasound. Application of pathway algorithms reveals numerous protein networks recruited in response to ultrasound including those regulating RNA splicing, cell-cell interactions and cytoskeletal organization. Our dataset also permits the informatic prediction of potential kinases responsible for the modifications detected. Taken together, our findings begin to reveal the endothelial proteomic response to ultrasound and suggest potential targets for future studies of the protective effects of ultrasound in the ischemic heart.

Neuroprotective gain of Apelin/APJ system

Apelin is an endogenous ligand of G protein-coupled receptor APJ. In recent years, many studies have shown that the apelin/APJ system has neuroprotective properties, such as anti-inflammatory, anti-oxidative stress, anti-apoptosis, and regulating autophagy, blocking excitatory toxicity. Apelin/APJ system has been proven to play a role in various neurological diseases and may be a promising therapeutic target for nervous system diseases. In this paper, the neuroprotective properties of the apelin/APJ system and its role in neurologic disorders are reviewed. Further understanding of the pathophysiological effect and mechanism of the apelin/APJ system in the nervous system will help develop new therapeutic interventions for various neurological diseases.

Current and Future Therapeutic Strategies for Limb Girdle Muscular Dystrophy Type R1: Clinical and Experimental Approaches

Limb girdle muscular dystrophy type R1 disease is a progressive disease that is caused by mutations in the CAPN3 gene and involves the extremity muscles of the hip and shoulder girdle. The CAPN3 protein has proteolytic and non-proteolytic properties. The functions of the CAPN3 protein that have been determined so far can be listed as remodeling and combining contractile proteins in the sarcomere with the substrates with which it interacts, controlling the Ca²⁺ flow in and out through the sarcoplasmic reticulum, and regulation of membrane repair and muscle regeneration. Even though there are several gene therapies, cellular therapies, and drug therapies, such as glucocorticoid treatment, AAV- mediated therapy, CRISPR-Cas9, induced pluripotent stem cells, MYO-029, and AMBMP, which are either in preclinical or clinical phases, or have been completed, there is no final cure. Inhibitors and small molecules (tauroursodeoxycholic acid, salubrinal, rapamycin, CDN1163, dwarf open reading frame) targeting ER stress factors that are thought to be effective in muscle loss can be considered potential therapy strategies. At present, little can be done to treat the progressive muscle wasting, loss of function, and premature mortality of patients with LGMDR1, and there is a pressing need for more research to develop potential therapies.

The Downregulation of ADAM17 Exerts Protective Effects against Cardiac Fibrosis by Regulating Endoplasmic Reticulum Stress and Mitophagy

Background

A disintegrin and metalloproteinase 17 (ADAM17) is a transmembrane protein that is widely expressed in various tissues; it mediates the shedding of many membrane-bound molecules, involving cell-cell and cell-matrix interactions. We investigated the role of ADAM17 within mouse cardiac fibroblasts (mCFs) in heart fibrosis.

Methods

mCFs were isolated from the hearts of neonatal mice. Effects of ADAM17 on the differentiation of mCFs towards myofibroblasts and their fibrotic behaviors following induction with TGF-β1 were examined. The expression levels of fibrotic proteins, such as collagen I and α-SMA, were assessed by qRT-PCR analysis and western blotting. Cell proliferation and migration were measured using the CCK-8 and wound healing assay. To identify the target gene for ADAM17, the protein levels of the components of endoplasmic reticulum (ER) stress and the PINK1/Parkin pathway were assessed following ADAM17 silencing. The effects of ADAM17 silencing or treatment with thapsigargin, a key stimulator of acute ER stress, on mCFs proliferation, migration, and collagen secretion were also examined. In vivo, we used a mouse model of cardiac fibrosis established by left anterior descending artery ligation; the mice were administered oral gavage with a selective ADAM17 inhibitor (TMI-005) for 4 weeks after the operation.

Results

We found that the ADAM17 expression levels were higher in fibrosis heart tissues and TGF-β1-treated mCFs. The ADAM17-specific siRNAs decreased TGF-β1-induced increase in the collagen secretion, proliferation, and migration of mCFs. Knockdown of ADAM17 reduces the activation of mCFs by inhibiting the ATF6 branch of ER stress and further activating mitophagy. Moreover, decreased ADAM17 expression also ameliorated cardiac fibrosis and improved heart function.

Conclusions

This study highlights that mCF ADAM17 expression plays a key role in cardiac fibrosis by regulating ER stress and mitophagy, thereby limiting fibrosis and improving heart function. Therefore, ADAM17 downregulation, within the physiological range, could exert protective effects against cardiac fibrosis.

The effect of nanoparticles of cobalt-chromium on human aortic endothelial cells in vitro

Despite advances in stent technology for vascular interventions, in-stent restenosis (ISR) remains a main complication. The corrosion of cobalt-chromium (CoCr) alloy coronary stents has been identified to be associated with ISR, whereas its role in ISR has not been elucidated. In the current work, CoCr nanoparticles, simulated corrosion products of CoCr alloy, were used to investigate their effect on the endothelial cells. It has been demonstrated that the cell viability declines and the cell membrane is damaged, indicating the cytotoxicity of CoCr nanoparticles. The expression of GRP78, CHOP, and cleaved-caspase12 proteins has increased when exposed to CoCr nanoparticles, suggesting that CoCr nanoparticles induced cell apoptosis through endoplasmic reticulum (ER) stress-mediated apoptotic pathway. An increased release of adhesion and inflammatory mediators was also induced by CoCr nanoparticles, including ICAM-1, VCAM-1, IL-1β, IL-6, and TNF-α. Our results demonstrated that CoCr nanoparticles could trigger apoptosis, adhesion, and inflammation. These findings indicated potential damaging effects of CoCr nanoparticles on the vascular endothelium, which suggested corrosion of CoCr alloy may promote the progression and development of ISR.

The long and winding road to target protein misfolding in cardiovascular diseases

BACKGROUND

In the last decades, cardiovascular diseases (CVD) have remained the first leading cause of mortality and morbidity in the world. Although several therapeutic approaches have been introduced in the past, the development of novel treatments remains an important research goal, which is hampered by the lack of understanding of key mechanisms and targets. Emerging evidences in recent years indicate the involvement of misfolded proteins aggregation and the derailment of protein quality control in the pathogenesis of cardiovascular diseases. Several potential interventions targeting protein quality control have been translated from the bench to the bedside to effectively employ the misfolded proteins as promising therapeutic targets for cardiac diseases, but with trivial results.

DESIGN

In this review, we describe the recent progresses in preclinical and clinical studies of protein misfolding and compromised protein quality control by selecting and reporting studies focusing on cardiovascular diseases including cardiomyopathies, cardiac amyloidosis, atherosclerosis, atrial fibrillation and thrombosis.

RESULTS

In preclinical models, modulators of several molecular targets (eg heat shock proteins, unfolded protein response, ubiquitin protein system, autophagy and histone deacetylases) have been tested in various conditions with promising results although lacking an adequate transition towards clinical setting.

CONCLUSIONS

At present, no therapeutic strategies have been reported to attenuate proteotoxicity in patients with CVD due to a lack of specific biomarkers for pinpointing upstream events in protein folding defects at a subclinical stage of the diseases requiring an intensive collaboration between basic scientists and clinicians.

Methylglyoxal stimulates endoplasmic reticulum stress in vascular smooth muscle cells

Methylglyoxal (MGO) is considered responsible for the detrimental effects of high blood glucose. MGO is produced as a by-product of the glycolysis pathway. While the glyoxalase system removes it, the system fails in people with diabetes. MGO concentration is detected as elevated in these patients. Endoplasmic reticulum (ER) stress may play a role in atherosclerosis progression and vascular diseases. If ER stress persists, it may result in apoptosis of the cell. As a result, stabilized plaque structure by these cells may be ruptured and cause a stroke. This study aimed to investigate whether MGO can induce ER stress and apoptosis in vascular smooth muscle cells (VSMCs). Also, the effects of aminoguanidine hydrochloride (AGH), 4-phenylbutyric acid (4-PBA), and tauroursodeoxycholic acid (TUDCA) were scrutinized to relieve ER stress. VSMCs were isolated from rat aorta and cultured primary. PERK phosphorylation, IRE1α, ATF6, BiP (Grp78), and CHOP expressions were detected by the western blot technique. A caspase-3 assay kit measured the apoptosis. MGO could stimulate the main three ER stress pathways, PERK phosphorylation, IRE1α, and ATF6 expressions in a time- and concentration-dependent manner. Furthermore, AGH, 4-PBA, and TUDCA alleviated MGO-induced ER stress. However, we detected neither an increase in CHOP expression nor apoptosis in VSMCs. This study shows that MGO induces ER stress even at low concentrations in VSMCs. The impaired glyoxalase system may cause MGO accumulation and result in persisted ER stress. Supposing that ER stress is not mitigated, this table might be finalized in cell apoptosis, plaque rupture, and stroke.