Novel interactions of GRP78: UPR and estrogen responses in the brain

Role of PERK-mediated pathway in the effect of mild hypothermia after cerebral ischaemia/reperfusion

BACKGROUND

Hypothermia is an effective method of reducing brain injury caused by a variety of neurological insults. It is aimed to elucidate whether a change in the expression of PERK-mediated pathway proteins is an indicator of the neuroprotective effect of mild hypothermia after cerebral ischaemia/reperfusion.

METHODS

One hundred and ninety-two male C57BL/6 mice were randomly divided into three groups: a sham group, a cerebral normothermic ischaemia/reperfusion (I/R) group and a cerebral hypothermic I/R group. A cerebral ischaemia model was established by ligating the bilateral common carotid artery for 15 min. Mice in the hypothermia group stayed in a cage that was set at 33°C, sprayed with a spray of 70% ethanol, and blown with two high-speed fans. The state of neurons was assessed on micropreparations stained with haematoxylin-eosin and TUNEL. The expressions of GRP78, p-perk, p-eif2α, ATF4 and CHOP were measured by western blot analysis 6, 12, 24 and 72 h after reperfusion.

RESULTS

The number of surviving cells was significantly higher in the hypothermia group than in the group without hypothermia (p < .05). The GRP78 expression in the hypothermia group was statistically higher (p < .05) than in the ischaemia/reperfusion group. Optical densities of p-perk, p-eif2α and ATF4 in hippocampus CA1 neurons ischaemia were statistically significantly lower in the hypothermia group than in the ischaemia/reperfusion group (p < .05). The CHOP expression in the hypothermia group was statistically lower (p < .05) than in the ischaemia/reperfusion group.

CONCLUSION

Mild hypothermia for 6 h promoted moderate neuroprotection by mediating the expression of GRP78, p-PERK, p-eIF2α, ATF4 and CHOP.

Lonp1 and Sig-1R contribute to the counteraction of ursolic acid against ochratoxin A-induced mitochondrial apoptosis

Ochratoxin A (OTA), a secondary fungal metabolite with nephrotoxicity, is widespread in numerous kinds of feeds and foodstuffs. Ursolic acid (UA), a water-insoluble pentacyclic triterpene acid, exists in a wide range of food materials and medicinal plants. Our earlier researches provided preliminary evidence that mitochondria- and mitochondria-associated endoplasmic reticulum membranes (MAMs)-located stress-responsive Lon protease 1 (Lonp1) had a protective function in OTA-induced nephrotoxicity, and the renoprotective function of UA against OTA partially due to Lonp1. However, whether other MAMs-located protiens, such as endoplasmic reticulum stress (ERS)-responsive Sigma 1-type opioid receptor (Sig-1R), contribute to the protection of UA against OTA-induced nephrotoxicity together with Lonp1 needs further investigation. In this study, the cell viability, reactive oxygen species, and protein expressions of human proximal tubule epithelial-originated kidney-2 (HK-2) cells varied with OTA and/or UA/CDDO-me/AVex-73/Sig-1R siRNA treatments were determined. Results indicated that a 24 h-treatment of 5 μM OTA could significantly induce mitochondrial-mediated apoptosis via repressing Lonp1 and Sig-1R, thereby enhancing the protein expressions of GRP78, p-PERK, p-eIF2α, CHOP, IRE1α, and Bax, and inhibiting the protein expression of Bcl-2 in HK-2 cells, which could be remarkably relieved by a 2 h-pre-treatment of 4 μM UA (P < 0.05). In conclusion, through mutual promotion between Lonp1 and Sig-1R, UA could effectively relieve OTA-induced apoptosis in vitro and break the vicious cycle between oxidative stress and ERS, which activated the mitochondrial apoptosis pathway.

Replication of standard bovine viral diarrhea strain OregonC24Va induces endoplasmic reticulum stress-mediated apoptosis of bovine trophoblast cells

Bovine viral diarrhea (BVD) is a worldwide infectious disease caused by bovine viral diarrhea virus (BVDV) infection, which invades the placenta, causes abortion, produces immune tolerance and continuously infects calves, and causes huge economic losses to the cattle industry. The endoplasmic reticulum (ER) is an important organelle in cells, which is prone to ER stress after being stimulated by pathogens, thus activating the ER stress-related apoptosis. Studies have confirmed that BVDV can utilize the ER of its host to complete its own proliferation and stimulate ER stress to a certain extent. However, the role of ER stress in BVDV infecting bovine placental trophoblast cells (BTCs) and inducing apoptosis is still unclear. We are using the cytopathic strain of BVDV (OregonC24Va), which can cause apoptosis of BTCs, as a model system to determine how ER stress induced by BVDV affects placental toxicity. We show that OregonC24Va can infect BTCs and proliferate in it. With the proliferation of BVDV in BTCs, ER stress-related apoptosis is triggered. The ER stress inhibitor 4-PBA was used to inhibit the ER stress of BTCs, which not only inhibited the proliferation of BVDV, but also reduced the apoptosis of BTCs. The ER stress activator Tg can activate ER stress-related apoptosis, but the proliferation of BVDV does not change in BTCs. Therefore, BVDV utilizes the UPR of activated ER stress to promote the proliferation of BVDV in the early stage of infection, and activates the ER stress-related apoptosis of BTCs in the later stage with the virus proliferation to promote the cell apoptosis and further spread of the virus. Our research provides a new theoretical basis for exploring the placental infection and vertical transmission of BVDV.

Age Worsens the Cognitive Phenotype in Mice Carrying the Thr92Ala-DIO2 Polymorphism

The Thr92Ala-Dio2 polymorphism has been associated with reduced cognition in 2-month-old male mice and increased risk for cognitive impairment and Alzheimer's disease in African Americans. This has been attributed to reduced thyroid hormone (TH) signaling and endoplasmic reticulum (ER) stress in the brain. Here we studied the Thr92Ala-Dio2 mouse model and saw that older male mice (7-8-month-old) exhibited a more severe cognition impairment, which extended to different aspects of declarative and working memories. A similar phenotype was observed in 4-5-month-old female mice. There were no structural alterations in the prefrontal cortex (PFC) and hippocampus of the Thr92Ala-Dio2 mouse. Nonetheless, in both male and female PFC, there was an enrichment in genes associated with TH-dependent processes, ER stress, and Golgi apparatus, while in the hippocampus there was additional enrichment in genes associated with inflammation and apoptosis. Reduced TH signaling remains a key mechanism of disease given that short-term treatment with L-T3 rescued the cognitive phenotype observed in males and females. We conclude that in mice, age is an additional risk factor for cognitive impairment associated with the Thr92Ala-Dio2 polymorphism. In addition to reduced TH signaling, ER-stress, and involvement of the Golgi apparatus, hippocampal inflammation and apoptosis were identified as potentially important mechanisms of a disease.

Involvement of calcium homeostasis and unfolded protein response in autophagy co-induced by molybdenum and cadmium in duck (Anas platyrhyncha) brain

Excess molybdenum (Mo) and cadmium (Cd) are harmful to animals, but neurotoxicity caused by Mo and Cd co-exposure in ducks is yet unknown. To assess joint impacts of Mo and Cd on autophagy via calcium homeostasis and unfolded protein response (UPR) in duck brain, 40 healthy 7-day-old ducks (Anas platyrhyncha) were assigned to 4 groups at random and fed diets supplemented with different doses of Mo or/and Cd for 16 weeks, respectively. Brain tissues were excised for experiment. Results exhibited that Mo or/and Cd disturbed calcium homeostasis by decreased ATPase activities and increased calcium (Ca) content, and upregulated calcium homeostasis-related factors Ca²⁺/CAM-dependent kinase IIɑ (CaMKIIɑ), calcineurin (CaN), inositol-1,4,5-trisphosphate receptor (IP₃R), and calreticulin (CRT) expression levels. Meanwhile, the upregulation of UPR-related factor expression levels indicated that Mo or/and Cd activated UPR. Moreover, Mo or/and Cd triggered autophagy through promoting the number of autophagosomes and LC3II immunofluorescence intensity and altering autophagy key factor expression levels. Correlation analysis showed that there were obvious connections among Ca²⁺ homeostasis, endoplasmic reticulum (ER) stress, and autophagy induced by Mo or/and Cd. Thence, it can be speculated that autophagy initiated by Mo or/and Cd may be associated with interfering Ca²⁺ homeostasis and triggering UPR.

Estrogen inhibits endoplasmic reticulum stress and ameliorates myocardial ischemia/reperfusion injury in rats by upregulating SERCA2a

Background

The incidence of coronary heart disease (CHD) in premenopausal women is significantly lower than that of men of the same age, suggesting protective roles of estrogen for the cardiovascular system against CHD. This study aimed to confirm the protective effect of estrogen on myocardium during myocardial ischemia/reperfusion (MI/R) injury and explore the underlying mechanisms.

Methods

Neonatal rat cardiomyocytes and Sprague–Dawley rats were used in this study. Different groups were treated by bilateral ovariectomy, 17β-estradiol (E2), adenoviral infection, or siRNA transfection. The expression of sarcoplasmic reticulum Ca²⁺ ATPase pump (SERCA2a) and endoplasmic reticulum (ER) stress-related proteins were measured in each group to examine the effect of different E2 levels and determine the relationship between SERCA2a and ER stress. The cell apoptosis, myocardial infarction size, levels of apoptosis and serum cardiac troponin I, ejection fraction, calcium transient, and morphology changes of the myocardium and ER were examined to verify the effects of E2 on the myocardium.

Results

Bilateral ovariectomy resulted in reduced SERCA2a levels and more severe MI/R injury. E2 treatment increased SERCA2a expression. Both E2 treatment and exogenous SERCA2a overexpression decreased levels of ER stress-related proteins and alleviated myocardial damage. In contrast, SERCA2a knockdown exacerbated ER stress and myocardial damage. Addition of E2 after SERCA2a knockdown did not effectively inhibit ER stress or reduce myocardial injury.

Conclusions

Our data demonstrate that estrogen inhibits ER stress and attenuates MI/R injury by upregulating SERCA2a. These results provide a new potential target for therapeutic intervention and drug discovery in CHD.

Combined effect of unfolded protein response and circZc3h4, circRNA Scar in mouse ovary and uterus damage induced by procymidone

Procymidone (PCM) is a fungicide commonly used to prevent and control plant diseases, and it is also an environmental endocrine disruptor that has a typical anti-androgen effect on the function and/or structure of the vertebrate reproductive system. The activation of the unfolded protein response (UPR) will fold the protein correctly to ensure the cell's survival. PCM regulates GRP78 by affecting the level of hormones, and there is a regulatory relationship between the UPR, the circRNAs and the miRNAs. In vivo experiments, PCM (suspended in soybean oil) was orally administered to adolescent female mice for 21 days in 3 different doses of 50 mg kg^-1 day^-1 (low dose), 100 mg kg^-1 day^-1 (medium dose) and 200 mg kg^-1 day^-1 (high dose) to cause ovaries and uteruses damage, and in vitro experiments, various doses of PCM from 0.33 × 10^-5 (low dose) to 1 × 10^-5 (medium dose) then 3 × 10^-5 M (high dose) were used to induce injury on the ovaries and uteri of the mice. We found out that both in vivo and in vitro, PCM caused dose-dependent damages to the ovaries and uteri, increased their circRNA Scar levels and decreased circZc3h4 abundance. Also, all UPR signaling pathways in the low-dose group and some in the middle-dose group were activated. It is speculated that UPR may antagonize the partial ovarian and uterine damage in adolescent mice induced by PCM at doses less than NOAEL via changes in circZc3h4 and circRNA Scar.

Electroacupuncture Regulates Endoplasmic Reticulum Stress and Ameliorates Neuronal Injury in Rats with Acute Ischemic Stroke

Ischemic stroke is a common cause of morbidity, mortality, and disability worldwide. Electroacupuncture (EA) is an effective method for alleviating brain damage after ischemic stroke. However, the underlying mechanism has not been fully elucidated. This study aimed to determine whether endoplasmic reticulum stress (ERS) could contribute to the protective effects of EA in cerebral ischemia/reperfusion injury (CIRI) to provide a rationale for the widespread clinical use of EA. Rats were divided into the sham-operated (sham) group, the CIRI (model) group, and the EA group. Rats in the model group were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by 72 h of reperfusion. Rats with CIRI were treated daily with EA at GV20 and ST36 for a total of 3 days. The Longa scoring system and adhesive removal somatosensory test were applied to evaluate neurological deficits. Then, 2,3,5-triphenyltetrazolium chloride (TTC) staining was performed to measure the infarct volume. Immunofluorescence staining for NeuN and GFAP and terminal deoxynucleotidyl transferase- (TdT-) mediated dUTP nick-end labeling (TUNEL) staining were performed to detect apoptotic cells in brain tissue. Immunohistochemistry, quantitative real-time polymerase chain reaction (qPCR), and western blotting were used to measure the levels of ERS indicators (GRP78, CHOP/GADD153, p-eIF2α, and caspase 12). The results showed that EA significantly reduced the cerebral infarct volume, improved neurological function, and inhibited neuronal apoptosis. In the EA group compared with the model group, the mRNA expression levels of GRP78 were significantly increased, and the expression levels of proapoptotic proteins (CHOP/GADD153, p-eIF2α, and caspase 12) were significantly decreased. These results suggest that the possible mechanism by which EA protects cells against neuronal injury in CIRI may involve inhibiting endoplasmic reticulum stress.

GRP78 targeting: Hitting two birds with a stone

BACKGROUND

Glucose regulating protein 78 (GRP78) is one member of the Heat Shock Protein family of chaperone proteins (HSPA5) found in eukaryotes. It acts as the master of the Unfolded Protein Response (UPR) process in the lumen of the Endoplasmic Reticulum (ER).

SCOPE

Under the stress of unfolded proteins, GRP78 binds to the unfolded proteins to prevent misfolding, while under the load of the unfolded protein, it drives the cell to autophagy or apoptosis. Several attempts reported the overexpression of GRP78 on the cell membrane of cancer cells and cells infected with viruses or fungi.

MAJOR CONCLUSIONS

Cell-surface GRP78 is used as a cancer cell target in previous studies. Additionally, GRP78 is used as a drug target to stop the progression of cancer cells by different compounds, including peptides, antibodies, and some natural compounds. Additionally, it can be used as a protein target to reduce the infectivity of different viruses, including the pandemic SARS-CoV-2. Besides, GRP78 targeting is used in diagnosis and imaging modalities using radionuclides.

GENERAL SIGNIFICANCE

This review summarizes the various attempts that used GRP78 both in therapy (fighting cancer, viral and fungal infections) and diagnosis (imaging).

Pioglitazone Attenuates Reoxygenation Injury in Renal Tubular NRK-52E Cells Exposed to High Glucose via Inhibiting Oxidative Stress and Endoplasmic Reticulum Stress

Renal ischemia-reperfusion injury is a major cause of acute kidney injury. In the present study, we investigated the effects of pioglitazone on hypoxia/reoxygenation (H/R) injury in rat renal tubular epithelial cells (RTECs) under normal- (NG) or high-glucose (HG) culture conditions via evaluating oxidative stress and endoplasmic reticulum stress (ERS). The RTECs (NRK-52E cells) were divided into six groups as follows: NG group, HG group, NG + H/R group, HG + H/R group, NG + Pio + H/R group, and HG + Pio + H/R group, among which cells in H/R groups were subjected to 4 h of hypoxia followed by 12 h of reoxygenation. After that, the cells were evaluated using the Cell Counting Kit-8 assay for the determination of their viability and flow cytometry assay for the detection of apoptosis. The levels of superoxide dismutase (SOD), glutathione reductase (GSH), catalase (CAT), and malondialdehyde (MDA) were determined via colorimetric chemical assays. In addition, the expression of ERS-associated proteins, i.e. ATF4, ATF6, GRP78, and CHOP, was determined via western blotting. A HG environment could reduce the viability and increase the apoptotic rate of NRK-52E cells with increased MDA levels and decreased SOD, CAT, and GSH levels, and upregulate the expression of ERS-associated proteins, i.e. ATF4, ATF6, and GRP78. H/R injury could further aggravate changes in the above indicators, but pioglitazone could significantly reverse such changes and alleviate cell injury. Thus, Pioglitazone exhibits a cytoprotective effect on RTECs against H/R injury under NG or HG culture conditions by inhibiting oxidative stress and ERS.

Nafamostat mesylate attenuates the pathophysiologic sequelae of neurovascular ischemia

Nafamostat mesylate, an apparent soi-disant panacea of sorts, is widely used to anticoagulate patients undergoing hemodialysis or cardiopulmonary bypass, mitigate the inflammatory response in patients diagnosed with acute pancreatitis, and reverse the coagulopathy of patients experiencing the commonly preterminal disseminated intravascular coagulation in the Far East. The serine protease inhibitor nafamostat mesylate exhibits significant neuroprotective effects in the setting of neurovascular ischemia. Nafamostat mesylate generates neuroprotective effects by attenuating the enzymatic activity of serine proteases, neuroinflammatory signaling cascades, and the endoplasmic reticulum stress responses, downregulating excitotoxic transient receptor membrane channel subfamily 7 cationic currents, modulating the activity of intracellular signal transduction pathways, and supporting neuronal survival (brain-derived neurotrophic factor/TrkB/ERK1/2/CREB, nuclear factor kappa B. The effects collectively reduce neuronal necrosis and apoptosis and prevent ischemia mediated disruption of blood-brain barrier microarchitecture. Investigational clinical applications of these compounds may mitigate ischemic reperfusion injury in patients undergoing cardiac, hepatic, renal, or intestinal transplant, preventing allograft rejection, and treating solid organ malignancies. Neuroprotective effects mediated by nafamostat mesylate support the wise conduct of randomized prospective controlled trials in Western countries to evaluate the clinical utility of this compound.

Suhuang antitussive capsule inhibits NLRP3 inflammasome activation and ameliorates pulmonary dysfunction via suppression of endoplasmic reticulum stress in cough variant asthma

Pulmonary dysfunction is tightly associated with cough variant asthma (CVA), a respiratory damage disease. Suhuang antitussive capsule (Suhuang), one of traditional Chinese patent medicines, plays a crucial role in the treatment and complication of CVA in the long clinical application. In this study, we aimed to investigate the protective effects and underlying antitussive mechanisms of Suhuang on pulmonary function in ovalbumin (OVA)-induced CVA rats. Administration (i.g.) of Suhuang significantly alleviated pulmonary damage and dysfunction. Suhuang improved ER stress and PKCε translocation via regulation of Ca²⁺ trafficking. Suhuang also inhibited NLRP3 inflammasome activation, as evidenced by disrupting the assembly of NLRP3 inflammasome and reducing the expression of cleaved caspase-1, and decreased IL-1β secretion. Besides, it's identified that TXNIP induction and RIP1-RIP3-Drp1 pathway were required for the inhibitory routes of Suhuang from ER stress to NLRP3 inflammasome activation. Consistent with the in vivo findings, Suhuang also attenuated ER stress/NLRP3 inflammasome activation, and thereby restored pulmonary homeostasis in vitro. Meantime, these functions were diminished by blocking ER stress, indicating that ER stress is essential for the effects of Suhuang on pulmonary function. A further in vivo analysis showed that Suhuang-driven pharmacological inactivation of NLRP3 inflammasome and amelioration of pulmonary dysfunction were reversed by an ER stress inducer tunicamycin, well confirming the beneficial effects of Suhuang on pulmonary function by regulation of ER stress. Collectively, these results indicated that Suhuang contributed to impairing NLRP3 inflammasome activation via inhibition of ER stress, which was responsible for the protection of pulmonary homeostasis. These findings may provide a pharmacological groundwork and important new experimental data regarding the clinical treatment of Suhuang in CVA patients.

Neuroprotective and Neurological/Cognitive Enhancement Effects of Curcumin after Brain Ischemia Injury with Alzheimer's Disease Phenotype

In recent years, ongoing interest in ischemic brain injury research has provided data showing that ischemic episodes are involved in the development of Alzheimer's disease-like neuropathology. Brain ischemia is the second naturally occurring neuropathology, such as Alzheimer's disease, which causes the death of neurons in the CA1 region of the hippocampus. In addition, brain ischemia was considered the most effective predictor of the development of full-blown dementia of Alzheimer's disease phenotype with a debilitating effect on the patient. Recent knowledge on the activation of Alzheimer's disease-related genes and proteins-e.g., amyloid protein precursor and tau protein-as well as brain ischemia and Alzheimer's disease neuropathology indicate that similar processes contribute to neuronal death and disintegration of brain tissue in both disorders. Although brain ischemia is one of the main causes of death in the world, there is no effective therapy to improve the structural and functional outcomes of this disorder. In this review, we consider the promising role of the protective action of curcumin after ischemic brain injury. Studies of the pharmacological properties of curcumin after brain ischemia have shown that curcumin has several therapeutic properties that include anti-excitotoxic, anti-oxidant, anti-apoptotic, anti-hyperhomocysteinemia and anti-inflammatory effects, mitochondrial protection, as well as increasing neuronal lifespan and promoting neurogenesis. In addition, curcumin also exerts anti-amyloidogenic effects and affects the brain's tau protein. These results suggest that curcumin may be able to serve as a potential preventive and therapeutic agent in neurodegenerative brain disorders.

Salidroside mitigates hypoxia/reoxygenation injury by alleviating endoplasmic reticulum stress‑induced apoptosis in H9c2 cardiomyocytes

Endoplasmic reticulum (ER) stress-induced apoptosis serves a crucial role in the development of myocardial ischemia/reperfusion (I/R) injury. Salidroside is a phenylpropanoid glycoside isolated from Rhodiola rosea L., which is a plant often used in traditional Chinese medicine. It possesses multiple pharmacological actions and protects against myocardial I/R injury in vitro and in vivo. However, it is not yet clear whether ER stress or ER stress-induced apoptosis contributes to the cardioprotective effects of salidroside against myocardial I/R injury. Hence, hypoxia/reoxygenation (H/R)-treated H9c2 cardiomyocytes were used in the current study to mimic myocardium I/R injury in vivo. It was hypothesized that salidroside alleviates ER stress and ER stress-induced apoptosis, thereby reducing H/R injury in H9c2 cells. The results demonstrated that salidroside attenuated H/R-induced H9c2 cardiomyocyte injury, as cell viability was increased, lactate dehydrogenase release was decreased, morphological changes in apoptotic cells were ameliorated and the apoptosis ratio was reduced compared with the H/R group. ER stress was reversed, indicated by the downregulation of glucose regulated protein 78 and C/EBP homologous protein following pretreatment with salidroside. In addition, salidroside attenuated ER stress-induced apoptosis, as the expression of cleaved caspase-12 and pro-apoptotic protein Bcl-2 associated X protein and activity of caspase-3 was decreased, while the expression of anti-apoptotic protein Bcl-2 was increased following pretreatment with salidroside. Furthermore, the results indicated that salidroside decreases the activation of the ER stress-associated signaling pathway, as the expression of phosphorylated protein kinase RNA (PKR)-like ER kinase (p-PERK) and phosphorylated inositol-requiring enzyme-1α (p-IRE1α) proteins were decreased following pretreatment with salidroside. These results demonstrate that salidroside protects against H/R injury via regulation of the PERK and IRE1α pathways, resulting in alleviation of ER stress or ER stress-induced apoptosis in H9c2 cardiomyocytes.

Protective Effects of Curcumin Against Ischemia-Reperfusion Injury in the Nervous System

Ischemia-reperfusion injury (I/R injury) is a common feature of ischemic stroke which occurs when blood supply is restored after a period of ischemia. Although stroke is an important cause of death in the world, effective therapeutic strategies aiming at improving neurological outcomes in this disease are lacking. Various studies have suggested the involvement of different mechanisms in the pathogenesis of I/R injury in the nervous system. These mechanisms include oxidative stress, platelet adhesion and aggregation, leukocyte infiltration, complement activation, blood-brain barrier (BBB) disruption, and mitochondria-mediated mechanisms. Curcumin, an active ingredient of turmeric, can affect all these pathways and exert neuroprotective activity culminating in the amelioration of I/R injury in the nervous system. In this review, we discuss the protective effects of curcumin against I/R injury in the nervous system and highlight the studies that have linked biological functions of curcumin and I/R injury improvement.

Estrogen receptor-α36-mediated rapid estrogen signaling regulates 78 kDa glucose-regulated protein expression in gastric carcinoma cells

To determine whether estrogen receptor-α36 (ER-α36) -mediated rapid estrogen signaling is associated with 78 kDa glucose-regulated protein (GRP78) expression in gastric cancer, 86 samples of gastric tumor tissue with corresponding normal and tumor-adjacent tissues were used to examine expression patterns of GRP78 and ER-α36. Immunohistochemistry demonstrated that 55/86 (63.95%) patients with gastric carcinoma, and western blot analysis revealed that GRP78 was upregulated in 15/20 (75%) of tumor specimens. GRP78 expression was positively associated with ER-α36 expression, the male sex and lymph node metastasis (P<0.05). Estrogen treatment increased GRP78 and ER-α36 expression, as well as GSK-3β phosphorylation in established gastric cancer SGC-7901 cells. The steady-state level of GRP78 protein expression and the level of phosphorylated GSK-3β at Ser9 were decreased in SGC-7901 cells with ER-α36 knockdown. Forced expression of ER-α36 in SGC-7901 cells, however, led to an increase in GRP78 expression and GSK-3β phosphorylation. It may therefore be concluded that ER-α36-mediated rapid estrogen signaling positively regulates GRP78 expression, presumably via the GSK-3β pathway, which may be associated with gastric carcinogenesis.

MicroRNA-21 suppresses ox-LDL-induced human aortic endothelial cells injuries in atherosclerosis through enhancement of autophagic flux: Involvement in promotion of lysosomal function

Atherosclerosis is a common pathological basis of cardiovascular disease and remains the leading cause of mortality. Endothelial cell (EC) injury and autophagy dysfunction have been proved to contribute to the development of atherosclerosis. Recently, accumulating evidence confirms that microRNAs (miRNAs) have emerged as vital regulators and fine-tuners of various pathophysiological cellular impacts and molecular signaling pathways involved in atherosclerosis. Herein, the objective of the present study was to explore the biological function of miR-21 in oxidized low-density lipoprotein (ox-LDL)-induced human aortic endothelial cells (HAECs) injury and the underlying molecular mechanism. The results showed that ox-LDL treatment significantly decreased HAECs viability, increased caspase-3 activity, apoptosis ratio and Bax protein expression, and reduced Bcl-2 protein expression resulting in EC injuries. Simultaneously, ox-LDL treatment obviously reduced miR-21 level in a time-and dose-dependent manner. Notably, ox-LDL-induced EC injuries were abolished by miR-21 mimics transfection. In addition, miR-21 mimics alleviated ox-LDL-induced impaired autophagic flux as illustrated by the increases in LC3-II/LC3-I ratio and Beclin-1 protein expression, and the decrease in p62 protein expression in HAECs. Moreover, ox-LDL suppressed the expressions of lysosomal membrane protein (LAMP1) and cathepsin D proteins, and attenuated cathepsin D activity in HAECs, leading to lysosomal dysfunction, while these effects were also blocked by miR-21 mimics. These findings indicated that miR-21 restored impaired autophagic flux and lysosomal dysfunction, thereby attenuating ox-LDL-induced HAECs injuries.

L-Type Calcium Channels Modulation by Estradiol

Voltage-gated calcium channels are key regulators of brain function, and their dysfunction has been associated with multiple conditions and neurodegenerative diseases because they couple membrane depolarization to the influx of calcium-and other processes such as gene expression-in excitable cells. L-type calcium channels, one of the three major classes and probably the best characterized of the voltage-gated calcium channels, act as an essential calcium binding proteins with a significant biological relevance. It is well known that estradiol can activate rapidly brain signaling pathways and modulatory/regulatory proteins through non-genomic (or non-transcriptional) mechanisms, which lead to an increase of intracellular calcium that activate multiple kinases and signaling cascades, in the same way as L-type calcium channels responses. In this context, estrogens-L-type calcium channels signaling raises intracellular calcium levels and activates the same signaling cascades in the brain probably through estrogen receptor-independent modulatory mechanisms. In this review, we discuss the available literature on this area, which seems to suggest that estradiol exerts dual effects/modulation on these channels in a concentration-dependent manner (as a potentiator of these channels in pM concentrations and as an inhibitor in nM concentrations). Indeed, estradiol may orchestrate multiple neurotrophic responses, which open a new avenue for the development of novel estrogen-based therapies to alleviate different neuropathologies. We also highlight that it is essential to determine through computational and/or experimental approaches the interaction between estradiol and L-type calcium channels to assist these developments, which is an interesting area of research that deserves a closer look in future biomedical research.

YiQiFuMai Powder Injection Ameliorates Cerebral Ischemia by Inhibiting Endoplasmic Reticulum Stress-Mediated Neuronal Apoptosis

YiQiFuMai (YQFM) powder injection as a modern preparation derived from Sheng Mai San, a traditional Chinese medicine, has been widely used in the treatment of cardiovascular and cerebrovascular diseases. However, its neuroprotective effect and underlying mechanism in cerebral ischemia remain to be explored. The present study was designed to investigate the neuroprotective effect of YQFM on endoplasmic reticulum (ER) stress-mediated neuronal apoptosis in the permanent middle cerebral artery occlusion- (MCAO-) injured mice and the oxygen-glucose deprivation- (OGD-) induced pheochromocytoma (PC12) cells. The results showed that single administration of YQFM (1.342 g/kg, i.p.) could reduce the brain infarction and improve the neurological deficits and the cerebral blood flow (CBF) after MCAO for 24 h in mice. Moreover, incubation with YQFM (100, 200, and 400 μg/mL) could increase the cell viability, decrease the caspase-3 activity, and inhibit the cell apoptosis in OGD-induced PC12 cells for 12 h. In addition, YQFM treatment could significantly modulate cleaved caspase-3 and Bcl-2 expressions and inhibit the expressions of ER stress-related marker proteins and signaling pathways in vivo and in vitro. In conclusion, our findings provide the first evidence that YQFM ameliorates cerebral ischemic injury linked with modulating ER stress-related signaling pathways, which provided some new insights for its prevention and treatment of cerebral ischemia diseases.

Tibolone protects T98G cells from glucose deprivation

The steroidal drug Tibolone is used for the treatment of climacteric symptoms and osteoporosis in post-menopausal women. Although Tibolone has been shown to exert neuroprotective actions after middle cerebral artery occlusion, its specific actions on glial cells have received very little attention. In the present study we have assessed whether Tibolone exerts protective actions in a human astrocyte cell model, the T98G cells, subjected to glucose deprivation. Our findings indicate that Tibolone decreases the effects of glucose deprivation on cell death, nuclear fragmentation, superoxide ion production, mitochondrial membrane potential, cytoplasmic calcium concentration and morphological parameters. These findings suggest that glial cells may participate in the neuroprotective actions of Tibolone in the brain.

Proteome modulation in H9c2 cardiac cells by microRNAs miR-378 and miR-378

MicroRNAs are a novel class of powerful endogenous regulators of gene expression. MiR-378 and miR-378* are localized in the first intron of the Ppargc1b gene that codes the transcriptional co-activator PGC-1β. The latter regulates energy expenditure as well as mitochondrial biogenesis. The miR-378:miR-378* hairpin is highly expressed in cardiac cells. To better assess their role in cardiomyocytes, we identified miR-378 and miR-378* targets via a proteomic screen. We established H9c2 cellular models of overexpression of miR-378 and miR-378* and identified a total of 86 down-regulated proteins in the presence of either one of these miRs. Functional annotation clustering showed that miR-378 and miR-378* regulate related pathways in cardiomyocytes, including energy metabolism, notably glycolysis, cytoskeleton, notably actin filaments and muscle contraction. Using bioinformatics algorithms we found that 20 proteins were predicted as direct targets of the miRs. We validated eight of these targets by quantitative RT-PCR and luciferase reporter assay. We found that miR-378 targets lactate dehydrogenase A and impacts on cell proliferation and survival whereas miR-378* targets cytoskeleton proteins actin and vimentin. Proteins involved in endoplasmic reticulum stress response such as chaperone and/or calcium buffering proteins GRP78, PPIA (cyclophilin A), calumenin, and GMMPA involved in glycosylation are repressed by these miRs. Our results show that the miR-378/378* hairpin establishes a connection among energy metabolism, cytoskeleton remodeling, and endoplasmic reticulum function through post-transcriptional regulation of key proteins involved in theses pathways.

Estetrol, molecular chaperones, and the epigenetics of longevity and cancer resistance

Evidence is given that replicative senescence--possibly as organismal aging--constitutes epigenetic phenomena, counteracted by homeostatic factors such as, e.g., the molecular chaperones, which are housekeeping molecules essential for the folding, repair, and transport of proteins, RNA, and DNA. Weakening of the chaperone defense with age probably contributes to the frailty in senescence. The present review presents evidence that the human fetal estrogen hormone estetrol, by promotion of chaperone functions, homeostasis, and cancer resistance, may prove useful as a supplement during human senescence.

Brefeldin a effectively inhibits cancer stem cell-like properties and MMP-9 activity in human colorectal cancer Colo 205 cells

Cancer stem cells (CSCs) are a small subset of cancer cells with indefinite potential for self-renewal and the capacity to drive tumorigenesis. Brefeldin A (BFA) is an antibiotic that is known to block protein transport and induce endoplasmic reticulum (ER) stress in eukaryotic cells, but its effects on colorectal CSCs are unknown. We investigated the inhibitory effect of BFA on human colorectal cancer Colo 205 cells. We found that BFA effectively reduced the survival of suspension Colo 205 cells (IC₅₀ = ~15 ng/mL) by inducing apoptosis, and inhibited the clonogenic activity of Colo 205 CSCs in tumorsphere formation assay and soft agar colony formation assay in the same nanogram per milliliter range. We also discovered that at such low concentrations, BFA effectively induced endoplasmic reticulum (ER) stress response as indicated by the increased mRNA expression of ER stress-related genes, such as glucose-regulated protein 78 (GRP78), X-box binding protein 1 (XBP1), and C/EBP homologous protein (CHOP). Finally, we found that BFA reduced the activity of matrix metallopeptidase 9 (MMP-9). These findings suggest that BFA can effectively suppress the progression of colorectal cancer during the tumorigenesis and metastasis stages. These results may lead to the development of novel therapies for the treatment of colorectal cancer.