GRP78: A cell's response to stress

Endoplasmic Reticulum Chaperones in Viral Infection: Therapeutic Perspectives

Viruses are intracellular parasites that subvert the functions of their host cells to accomplish their infection cycle. The endoplasmic reticulum (ER)-residing chaperone proteins are central for the achievement of different steps of the viral cycle, from entry and replication to assembly and exit. The most abundant ER chaperones are GRP78 (78-kDa glucose-regulated protein), GRP94 (94-kDa glucose-regulated protein), the carbohydrate or lectin-like chaperones calnexin (CNX) and calreticulin (CRT), the protein disulfide isomerases (PDIs), and the DNAJ chaperones. This review will focus on the pleiotropic roles of ER chaperones during viral infection. We will cover their essential role in the folding and quality control of viral proteins, notably viral glycoproteins which play a major role in host cell infection. We will also describe how viruses co-opt ER chaperones at various steps of their infectious cycle but also in order to evade immune responses and avoid apoptosis. Finally, we will discuss the different molecules targeting these chaperones and the perspectives in the development of broad-spectrum antiviral drugs.

Mechanism of subchronic vinyl chloride exposure combined with a high-fat diet on hepatic steatosis

Vinyl chloride (VC) is a common industrial organic chlorine and environmental pollutant. In recent years, the dietary structure of residents especially Chinese has gradually shifted to western dietary patterns. VC aggravates dietary fatty acid-induced hepatic steatosis, but its mechanism is still unclear. And if the risk factors for steatosis persist, more severe diseases such as fibrosis and cirrhosis will occur. Therefore, we studied the effects and mechanisms of VC (160 and 800 mg/m³ ) and its metabolite (chloroacetaldehyde, 2.25, 4.5, and 9 μM) on hepatic steatosis of high-fat diet (HFD)-fed mice and palmitic acid (PA, 100 μM) treated HepG2 cells. Liver and serum biochemical indicators and pathological staining of the liver showed that the hepatic steatosis of VC combined with HFD groups was more severe than that of single-exposure groups (HFD group, low-dose VC group, and high-dose VC group). Moreover, VC enhanced HFD-induced oxidative stress (OS) and endoplasmic reticulum stress (ERS) and further upregulated the expression of sterol regulatory element-binding protein 1 (SREBP-1) and FAS. Besides, antioxidants and ERS inhibitors reduced the steatosis of HepG2 cells induced by VC metabolites and PA. These results suggest that VC exposure can enhance the degree of hepatic steatosis in HFD-fed mice. VC combined with HFD led to OS and ERS and upregulated the expression of de novo lipogenesis-related proteins, which may be related to the occurrence of hepatic steatosis. And the increased expression of CYP2E1 induced by VC combined with HFD may be the cause of OS.

GRP78 expression and prognostic significance in patients with pancreatic ductal adenocarcinoma treated with neoadjuvant therapy versus surgery first

BACKGROUND

Glucose-regulated protein 78 (GRP78) plays an essential role in protein folding, transportation, and degradation, thus regulates ER homeostasis and promotes cell survival, proliferation and invasion. GRP78 expression in PDAC patients who received neoadjuvant therapy has not been reported.

METHODS

This retrospective study of resected PDAC patients included 125 patients treated with neoadjuvant therapy (NAT) and 140 patients treated with surgery first (SF). The expression of GRP78 was evaluated by immunohistochemistry on tissue microarrays and the results were correlated with clinicopathologic parameters and survival.

RESULTS

GRP78 expression was higher in SF patients compared to NAT patients (P < 0.001). In SF cohort, the median disease-free survival (DFS) and overall survival (OS) for patients with GRP78-positive tumors were 11.2 months and 25.0 months, respectively, compared to DFS of 52.1 months (P = 0.008) and OS of 69.5 months (P = 0.02) for those with GRP78-negative tumors. GRP78 expression correlated with higher frequency of recurrent/metastasis (P = 0.045). In NAT cohort, GRP78 expression correlated with shorter OS (P = 0.03), but not DFS (P = 0.08). GRP78 expression was an independent prognosticator for both DFS (P = 0.02) and OS (P = 0.049) in SF cohort and was an independent prognosticator for OS (P = 0.03), but not for DFS (P = 0.06) in NAT cohort by multivariate analysis.

CONCLUSIONS

Our study showed that GRP78 expression in NAT cohort is lower than that in SF cohort. GRP78 expression correlated with shorter survival in both SF and NAT patients. Our findings suggest that targeting GRP78 may help to improve the prognosis in PDAC patients.

Catechins: Therapeutic Perspectives in COVID-19-Associated Acute Kidney Injury

Data obtained from several intensive care units around the world have provided substantial evidence of the strong association between impairment of the renal function and in-hospital deaths of critically ill COVID-19 patients, especially those with comorbidities and requiring renal replacement therapy (RRT). Acute kidney injury (AKI) is a common renal disorder of various etiologies characterized by a sudden and sustained decrease of renal function. Studies have shown that 5-46% of COVID-19 patients develop AKI during hospital stay, and the mortality of those patients may reach up to 100% depending on various factors, such as organ failures and RRT requirement. Catechins are natural products that have multiple pharmacological activities, including anti-coronavirus and reno-protective activities against kidney injury induced by nephrotoxic agents, obstructive nephropathies and AKI accompanying metabolic and cardiovascular disorders. Therefore, in this review, we discuss the anti-SARS-CoV-2 and reno-protective effects of catechins from a mechanistic perspective. We believe that catechins may serve as promising therapeutics in COVID-19-associated AKI due to their well-recognized anti-SARS-CoV-2, and antioxidant and anti-inflammatory properties that mediate their reno-protective activities.

Identification of a miRNA-mRNA Regulatory Networks in Placental Tissue Associated With Tibetan High Altitude Adaptation

The Tibetan population has lived and successfully reproduced at high altitude for many generations. Studies have shown that Tibetans have various mechanisms for protection against high-altitude hypoxia, which are probably due, at least in part, to placental adaptation. However, comprehensive in silico analyses of placentas in Tibetans are lacking. We performed a microarray-based comparative transcriptome analysis of 10 Tibetan women from Yushu, Qinghai, CHN (∼3,780 m) and 10 European women living in Leadville, CO, United States (∼3,100 m) for less than three generations. Expression of HIF-1α, STAT3, EGFR, HSP5A, XBP1, and ATF6A mRNA was less in the Tibetan placentas as compared with European placentas. A total of 38 miRNAs were involved in regulating these genes. Differentially expressed genes were enriched for HIF1α signaling pathways, protein processing in the endoplasmic reticulum, PI3K-AKT signaling pathways, and MAPK signaling pathways. Based on the transcriptome profiles, the Tibetan population was distinct from the European population; placental tissues from the Tibetan population are lacking hypoxic responses, and “passivation” occurs in response to hypoxic stress. These results provide insights into the molecular signature of adaptation to high altitudes in these two populations.

Current Understanding in the Pathophysiology of SARS-CoV-2-Associated Rhino-Orbito-Cerebral Mucormycosis: A Comprehensive Review

AIM

Recently, with the second wave of COVID-19, the Indian subcontinent has witnessed a dramatic rise in mucormycosis infection in patients recovered from COVID-19. This association has been documented in various case reports/case series and institutional experiences, and the mortality associated with this fungal infection is emerging as a cause of concern. The aim of the present paper is to provide a scientific overview on the pathogenesis of mucormycosis in COVID-19 beyond the conventional understanding of the disease process, which may not otherwise explain the increased incidence of mucormycosis in SARS-CoV-2.

METHODOLOGY

This paper is structured as a narrative review of the published literature on the pathogenesis of COVID-19 which contributes to the development of mucormycosis. Apart from the acknowledged role of ketoacidosis, high blood sugar, and iron metabolism in the pathogenesis of mucormycosis, other factors involved in pathophysiology of COVID-19 which might alter or enhance the mucormycosis infection such as (1) the role of ferritin, (2) high serum iron, (3) free radical-induced endothelitis, (4) hepcidin activation, (5) upregulation of glucose receptor protein (GRP78) are discussed in the pathophysiology of COVID-19-associated mucormycosis.

CONCLUSION

A new proposal for the pathogenesis based on the ferritin, viral mimicry of hepcidin and GRP78-CotH3 interaction, which clearly explains the surge in mucormycosis in SARS-CoV-2 infection, has been explained.

Pneumocytes are distinguished by highly elevated expression of the ER stress biomarker GRP78, a co-receptor for SARS-CoV-2, in COVID-19 autopsies

Vaccinations are widely credited with reducing death rates from COVID-19, but the underlying host-viral mechanisms/interactions for morbidity and mortality of SARS-CoV-2 infection remain poorly understood. Acute respiratory distress syndrome (ARDS) describes the severe lung injury, which is pathologically associated with alveolar damage, inflammation, non-cardiogenic edema, and hyaline membrane formation. Because proteostatic pathways play central roles in cellular protection, immune modulation, protein degradation, and tissue repair, we examined the pathological features for the unfolded protein response (UPR) using the surrogate biomarker glucose-regulated protein 78 (GRP78) and co-receptor for SARS-CoV-2. At autopsy, immunostaining of COVID-19 lungs showed highly elevated expression of GRP78 in both pneumocytes and macrophages compared with that of non-COVID control lungs. GRP78 expression was detected in both SARS-CoV-2-infected and un-infected pneumocytes as determined by multiplexed immunostaining for nucleocapsid protein. In macrophages, immunohistochemical staining for GRP78 from deceased COVID-19 patients was increased but overlapped with GRP78 expression taken from surgical resections of non-COVID-19 controls. In contrast, the robust in situ GRP78 immunostaining of pneumocytes from COVID-19 autopsies exhibited no overlap and was independent of age, race/ethnicity, and gender compared with that from non-COVID-19 controls. Our findings bring new insights for stress-response pathways involving the proteostatic network implicated for host resilience and suggest that targeting of GRP78 expression with existing therapeutics might afford an alternative therapeutic strategy to modulate host-viral interactions during SARS-CoV-2 infections.

Honokiol regulates endoplasmic reticulum stress by promoting the activation of the sirtuin 1-mediated protein kinase B pathway and ameliorates high glucose/high fat-induced dysfunction in human umbilical vein endothelial cells

Honokiol plays an important role in anti-oxidation, but its role in diabetic vascular complications is unclear. In this study, the effects of honokiol in high glucose/high fat (HG/HF)-induced human umbilical vein endothelial cells (HUVECs) were explored. After pre-treatment with honokiol, the cells were transferred to an HG/HF medium, and cell viability and apoptosis were respectively measured by methyl tetrazolium and flow cytometry. Moreover, the contents of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured. The expressions of C/EBP homologous protein (CHOP), glucose-regulated protein 78 (GRP78), phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase (p-PERK), phosphorylated-inositol requiring enzyme-1α (p-IRE1α), cleaved caspase-3 and SIRT1 were determined by Western blot or quantitative reverse transcription PCR, respectively. Finally, the viability, apoptosis, and the contents of ROS, MDA, and SOD, as well as the expressions of CHOP, GRP78, p-PERK, p-IRE1α, cleaved caspase-3, Akt, p-Akt, and SIRT1 in the cells transfected with small interfering RNA SIRT1 (siSIRT1) were detected by the previously mentioned methods. Honokiol reversed the effect of HG/HF on promoting cell apoptosis, ROS and MDA contents, and the expressions of CHOP, GRP78, p-PERK, p-IRE1α and cleaved caspase-3, and also reversed the inhibitory effect of HG/HF on cell viability, SOD content and SIRT1 expression. However, siSIRT1 reversed the above effects caused by honokiol. Honokiol activated SIRT1 promoter. SIRT1 interacted with Akt, consequently promoting the activity of Akt. Therefore, honokiol activates the Akt pathway by regulating SIRT1 expression to regulate endoplasmic reticulum stress, promotes cell viability and inhibits the apoptosis of HG/HF-induced HUVECs.

Long-term exposure to environmental level of phenanthrene causes adaptive immune response and fibrosis in mouse kidneys

As ubiquitous, persistent organic pollutants, polycyclic aromatic hydrocarbons (PAHs) have adverse impacts on human health. Phenanthrene (Phe) is one of the most abundant PAHs in the environment. However, the long-term effects of exposure to environmental level of Phe on the kidneys and the potential mechanisms are unclear. T helper (Th) cells, a subtype of CD4⁺ T cells that play a central role in the renal immune microenvironment. In this study, male mice were chronically exposed to 5, 50, and 500 ng/kg bw Phe every other day for total 210 days. Those results indicated that environmental Phe exposure caused kidney hypertrophy, injury and fibrosis in the mice. Chronic, long-term environmental level of Phe exposure did not significantly alter the innate immune response but induced adaptive immune response changes (Th1/Th2 related cytokines release), causing a type 1 immune response in the 5 ng/kg bw Phe group and a type 2 immune response in the high dose groups (50 and 500 ng/kg bw). This study provides novel insights into the roles of adaptive immune response in long-term PAH exposure-induced chronic kidney injury and fibrosis, which is beneficial for further understanding the potential health hazards of PAHs and providing new avenues for immune intervention strategies to alleviate PAHs toxicity.

Redox modulation of vitagenes via plant polyphenols and vitamin D: Novel insights for chemoprevention and therapeutic interventions based on organoid technology

Polyphenols are chemopreventive through the induction of nuclear factor erythroid 2 related factor 2 (Nrf2)-mediated proteins and anti-inflammatory pathways. These pathways, encoding cytoprotective vitagenes, include heat shock proteins, such as heat shock protein 70 (Hsp70) and heme oxygenase-1 (HO-1), as well as glutathione redox system to protect against cancer initiation and progression. Phytochemicals exhibit biphasic dose responses on cancer cells, activating at low dose, signaling pathways resulting in upregulation of vitagenes, as in the case of the Nrf2 pathway upregulated by hydroxytyrosol (HT) or curcumin and NAD/NADH-sirtuin-1 activated by resveratrol. Here, the importance of vitagenes in redox stress response and autophagy mechanisms, as well as the potential use of dietary antioxidants in the prevention and treatment of multiple types of cancer are discussed. We also discuss the possible relationship between SARS-CoV-2, inflammation and cancer, exploiting innovative therapeutic approaches with HT-rich aqueous olive pulp extract (Hidrox®), a natural polyphenolic formulation, as well as the rationale of Vitamin D supplementation. Finally, we describe innovative approaches with organoids technology to study human carcinogenesis in preclinical models from basic cancer research to clinical practice, suggesting patient-derived organoids as an innovative tool to test drug toxicity and drive personalized therapy.

Virtual screening-driven drug discovery of SARS-CoV2 enzyme inhibitors targeting viral attachment, replication, post-translational modification and host immunity evasion infection mechanisms

The novel coronavirus SARS-CoV2, the causative agent of the pandemic disease COVID-19, emerged in December 2019 forcing lockdown of communities in many countries. The absence of specific drugs and vaccines, the rapid transmission of the virus, and the increasing number of deaths worldwide necessitated the discovery of new substances for anti-COVID-19 drug development. With the aid of bioinformatics and computational modelling, ninety seven antiviral secondary metabolites from fungi were docked onto five SARS-CoV2 enzymes involved in viral attachment, replication, post-translational modification, and host immunity evasion infection mechanisms followed by molecular dynamics simulation and in silico ADMET prediction (absorption, distribution, metabolism, excretion and toxicity) of the hit compounds. Thus, three fumiquinazoline alkaloids scedapin C (15), quinadoline B (19) and norquinadoline A (20), the polyketide isochaetochromin D1 (8), and the terpenoid 11a-dehydroxyisoterreulactone A (11) exhibited high binding affinities on the target proteins, papain-like protease (PLpro), chymotrypsin-like protease (3CLpro), RNA-directed RNA polymerase (RdRp), non-structural protein 15 (nsp15), and the spike binding domain to GRP78. Molecular dynamics simulation was performed to optimize the interaction and investigate the stability of the top-scoring ligands in complex with the five target proteins. All tested complexes were found to have dynamic stability. Of the five top-scoring metabolites, quinadoline B (19) was predicted to confer favorable ADMET values, high gastrointestinal absorptive probability and poor blood-brain barrier crossing capacities.Communicated by Ramaswamy H. Sarma.

Heat shock proteins and exosomes in cancer theranostics

Heat shock proteins (HSPs) are a superfamily of molecular chaperones that were discovered through their ability to be induced by different stresses including heat shock. Other than their function as chaperones in proteins homeostasis, HSPs have been shown to inhibit different forms of cell death and to participate in cell proliferation and differentiation processes. Because cancer cells have to rewire their metabolism, they require a high amount of these stress-inducible chaperones for their survival. Therefore, HSPs are unusually abundant in cancer cells where they have oncogene-like functions. In cancer, HSPs have been involved in the regulation of apoptosis, immune responses, angiogenesis, metastasis and treatment resistance. Recently, HSPs have been shown to be secreted through exosomes by cancer cells. These tumor-derived exosomes can be used as circulating markers: HSP-exosomes have been reported as biomarkers of cancer dissemination, response to therapy and/or patient outcome. A new range of functions, mostly in modulation of anticancer immune responses, have been described for these extracellular HSPs. In this review, we will describe those recently reported functions of HSP-exosomes that makes them both targets for anticancer therapeutics and biomarkers for the monitoring of the disease. We will also discuss their emerging interest in cancer vaccines.

Melatonin relieves heat-induced spermatocyte apoptosis in mouse testes by inhibition of ATF6 and PERK signaling pathways

Normal spermatogenic processes require the scrotal temperature to be lower than that of the body as excessive heat affects spermatogenesis in the testes, reduces sperm quality and quantity, and even causes infertility. Endoplasmic reticulum stress (ERS) is a crucial factor in many pathologies. Although several studies have linked ERS to heat stress, researchers have not yet determined which ERS signaling pathways contribute to heat-induced testicular damage. Melatonin activates antioxidant enzymes, scavenges free radicals, and protects the testes from inflammation; however, few studies have reported on the influence of melatonin on heat-induced testicular damage. Using a murine model of testicular hyperthermia, we observed that heat stress causes both ERS and apoptosis in the testes, especially in the spermatocytes. These observations were confirmed using the mouse spermatocyte cell line GC2, where the Atf6 and Perk signaling pathways were activated during heat stress. Knockout of the above genes effectively reduced spermatocyte damage caused by heat stress. Pretreatment with melatonin alleviated heat-induced apoptosis by inhibiting the Atf6 and Perk signaling pathways. This mitigation was dependent on the melatonin receptors. In vivo experiments verified that melatonin treatment relieved heat-induced testicular damage. In conclusion, our results demonstrated that ATF6 and PERK are important mediators for heat-induced apoptosis, which can be prevented by melatonin treatment. Thus, our study highlights melatonin as a potential therapeutic agent in mammals for subfertility/infertility induced by testicular hyperthermia.

GRP78 determines glioblastoma sensitivity to UBA1 inhibition-induced UPR signaling and cell death

Glioblastoma multiforme (GBM) is an extremely aggressive brain tumor for which new therapeutic approaches are urgently required. Unfolded protein response (UPR) plays an important role in the progression of GBM and is a promising target for developing novel therapeutic interventions. We identified ubiquitin-activating enzyme 1 (UBA1) inhibitor TAK-243 that can strongly induce UPR in GBM cells. In this study, we evaluated the functional activity and mechanism of TAK-243 in preclinical models of GBM. TAK-243 significantly inhibited the survival, proliferation, and colony formation of GBM cell lines and primary GBM cells. It also revealed a significant anti-tumor effect on a GBM PDX animal model and prolonged the survival time of tumor-bearing mice. Notably, TAK-243 more effectively inhibited the survival and self-renewal ability of glioblastoma stem cells (GSCs) than GBM cells. Importantly, we found that the expression level of GRP78 is a key factor in determining the sensitivity of differentiated GBM cells or GSCs to TAK-243. Mechanistically, UBA1 inhibition disrupts global protein ubiquitination in GBM cells, thereby inducing ER stress and UPR. UPR activates the PERK/ATF4 and IRE1α/XBP signaling axes. These findings indicate that UBA1 inhibition could be an attractive strategy that may be potentially used in the treatment of patients with GBM, and GRP78 can be used as a molecular marker for personalized treatment by targeting UBA1.

Insight into the Web of Stress Responses Triggered at Gene Expression Level by Porphyrin-PDT in HT29 Human Colon Carcinoma Cells

Photodynamic therapy (PDT), a highly targeted therapy with acceptable side effects, has emerged as a promising therapeutic option in oncologic pathology. One of the issues that needs to be addressed is related to the complex network of cellular responses developed by tumor cells in response to PDT. In this context, this study aims to characterize in vitro the stressors and the corresponding cellular responses triggered by PDT in the human colon carcinoma HT29 cell line, using a new asymmetric porphyrin derivative (P2.2) as a photosensitizer. Besides investigating the ability of P2.2-PDT to reduce the number of viable tumor cells at various P2.2 concentrations and fluences of the activating light, we assessed, using qRT-PCR, the expression levels of 84 genes critically involved in the stress response of PDT-treated cells. Results showed a fluence-dependent decrease of viable tumor cells at 24 h post-PDT, with few cells that seem to escape from PDT. We highlighted following P2.2-PDT the concomitant activation of particular cellular responses to oxidative stress, hypoxia, DNA damage and unfolded protein responses and inflammation. A web of inter-connected stressors was induced by P2.2-PDT, which underlies cell death but also elicits protective mechanisms that may delay tumor cell death or even defend these cells against the deleterious effects of PDT.

Review: Vaspin (SERPINA12) Expression and Function in Endocrine Cells

Proper functioning of the body depends on hormonal homeostasis. White adipose tissue is now known as an endocrine organ due to the secretion of multiple molecules called adipokines. These proteins exert direct effects on whole body functions, including lipid metabolism, angiogenesis, inflammation, and reproduction, whereas changes in their level are linked with pathological events, such as infertility, diabetes, and increased food intake. Vaspin-visceral adipose tissue-derived serine protease inhibitor, or SERPINA12 according to serpin nomenclature, is an adipokine discovered in 2005 that is connected to the development of insulin resistance, obesity, and inflammation. A significantly higher amount of vaspin was observed in obese patients. The objective of this review was to summarize the latest findings about vaspin expression and action in endocrine tissues, such as the hypothalamus, pituitary gland, adipose tissue, thyroid, ovary, placenta, and testis, as well as discuss the link between vaspin and pathologies connected with hormonal imbalance.

Evaluation of vertical transmission of SARS-CoV-2 in utero: Nine pregnant women and their newborns

INTRODUCTION

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mainly transmitted by droplets and close contact, has caused a pandemic worldwide as of March 2020. According to the current case reports and cohort studies, the symptoms of pregnant women infected with SARS-CoV-2 were similar to normal adults and may cause a series of adverse consequences of pregnancy (placental abruption, fetal distress, epilepsy during pregnancy, etc.). However, whether SARS-CoV-2 can be transmitted to the fetus through the placental barrier is still a focus of debate.

METHODS

In this study, in order to find out whether SARS-CoV-2 can infect fetus through the placental barrier, we performed qualitative detection of virus structural protein (spike protein and nucleoprotein) and targeted receptor protein Angiotensin Converting Enzyme 2 (ACE2), Basigin (CD147) and molecular chaperone GRP78 expression on the placental tissue of seven pregnant women diagnosed with COVID-19 through immunohistochemistry. Amniotic fluid, neonatal throat, anal swab and breastmilk samples were collected immediately in the operating room or delivery room for verification after delivery, which were all tested for SARS-CoV-2 by reverse transcriptionpolymerase chain reaction (RT-PCR).

RESULTS/DISCUSSION

The result showed that CD147 was expressed on the basal side of the chorionic trophoblast cell membrane and ACE2 was expressed on the maternal side, while GRP78 was strongly expressed in the cell membrane and cytoplasm. The RT-PCR results of Amniotic fluid, neonatal throat, anal swab and breastmilk samples were all negative. On the basis of these findings, we speculated that it may be due to the placental barrier between mother and baby, for example, villous matrix and interstitial blood vessels have low expression of virus-related receptors (ACE2, CD147, GRP78), the probability of vertical transmission of SARS-CoV-2 through the placenta is low.

More Is Always Better Than One: The N-Terminal Domain of the Spike Protein as Another Emerging Target for Hampering the SARS-CoV-2 Attachment to Host Cells

Although the approved vaccines are proving to be of utmost importance in containing the Coronavirus disease 2019 (COVID-19) threat, they will hardly be resolutive as new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, a single-stranded RNA virus) variants might be insensitive to the immune response they induce. In this scenario, developing an effective therapy is still a dire need. Different targets for therapeutic antibodies and diagnostics have been identified, among which the SARS-CoV-2 spike (S) glycoprotein, particularly its receptor-binding domain, has been defined as crucial. In this context, we aim to focus attention also on the role played by the S N-terminal domain (S1-NTD) in the virus attachment, already recognized as a valuable target for neutralizing antibodies, in particular, building on a cavity mapping indicating the presence of two druggable pockets and on the recent literature hypothesizing the presence of a ganglioside-binding domain. In this perspective, we aim at proposing S1-NTD as a putative target for designing small molecules hopefully able to hamper the SARS-CoV-2 attachment to host cells.

Ruthenium Complexes in the Fight against Pathogenic Microorganisms. An Extensive Review

The widespread use of antibiotics has resulted in the emergence of drug-resistant populations of microorganisms. Clearly, one can see the need to develop new, more effective, antimicrobial agents that go beyond the explored 'chemical space'. In this regard, their unique modes of action (e.g., reactive oxygen species (ROS) generation, redox activation, ligand exchange, depletion of substrates involved in vital cellular processes) render metal complexes as promising drug candidates. Several Ru (II/III) complexes have been included in, or are currently undergoing, clinical trials as anticancer agents. Based on the in-depth knowledge of their chemical properties and biological behavior, the interest in developing new ruthenium compounds as antibiotic, antifungal, antiparasitic, or antiviral drugs has risen. This review will discuss the advantages and disadvantages of Ru (II/III) frameworks as antimicrobial agents. Some aspects regarding the relationship between their chemical structure and mechanism of action, cellular localization, and/or metabolism of the ruthenium complexes in bacterial and eukaryotic cells are discussed as well. Regarding the antiviral activity, in light of current events related to the Covid-19 pandemic, the Ru (II/III) compounds used against SARS-CoV-2 (e.g., BOLD-100) are also reviewed herein.

Reprogramming of microRNA expression via E2F1 downregulation promotes Salmonella infection both in infected and bystander cells

Cells infected with pathogens can contribute to clearing infections by releasing signals that instruct neighbouring cells to mount a pro-inflammatory cytokine response, or by other mechanisms that reduce bystander cells’ susceptibility to infection. Here, we show the opposite effect: epithelial cells infected with Salmonella Typhimurium secrete host factors that facilitate the infection of bystander cells. We find that the endoplasmic reticulum stress response is activated in both infected and bystander cells, and this leads to activation of JNK pathway, downregulation of transcription factor E2F1, and consequent reprogramming of microRNA expression in a time-dependent manner. These changes are not elicited by infection with other bacterial pathogens, such as Shigella flexneri or Listeria monocytogenes. Remarkably, the protein HMGB1 present in the secretome of Salmonella-infected cells is responsible for the activation of the IRE1 branch of the endoplasmic reticulum stress response in non-infected, neighbouring cells. Furthermore, E2F1 downregulation and the associated microRNA alterations promote Salmonella replication within infected cells and prime bystander cells for more efficient infection.

Cells infected with pathogens can release signals that instruct neighbouring cells to mount an immune response or that reduce these cells’ susceptibility to infection. Here, Aguilar et al. show the opposite effect: cells infected with Salmonella Typhimurium secrete host factors that facilitate the infection of bystander cells by activating their ER-stress response.

USP22 promotes HER2-driven mammary carcinoma aggressiveness by suppressing the unfolded protein response

The Ubiquitin-Specific Protease 22 (USP22) is a deubiquitinating subunit of the mammalian SAGA transcriptional co-activating complex. USP22 was identified as a member of the so-called "death-from-cancer" signature predicting therapy failure in cancer patients. However, the importance and functional role of USP22 in different types and subtypes of cancer remain largely unknown. In the present study, we leveraged human cell lines and genetic mouse models to investigate the role of USP22 in HER2-driven breast cancer (HER2+-BC) and demonstrate for the first time that USP22 is required for the tumorigenic properties in murine and human HER2+-BC models. To get insight into the underlying mechanisms, we performed transcriptome-wide gene expression analyses and identified the Unfolded Protein Response (UPR) as a pathway deregulated upon USP22 loss. The UPR is normally induced upon extrinsic or intrinsic stresses that can promote cell survival and recovery if shortly activated or programmed cell death if activated for an extended period. Strikingly, we found that USP22 actively suppresses UPR induction in HER2+-BC cells by stabilizing the major endoplasmic reticulum (ER) chaperone HSPA5. Consistently, loss of USP22 renders tumor cells more sensitive to apoptosis and significantly increases the efficiency of therapies targeting the ER folding capacity. Together, our data suggest that therapeutic strategies targeting USP22 activity may sensitize tumor cells to UPR induction and could provide a novel, effective approach to treat HER2+-BC.

Natural products may interfere with SARS-CoV-2 attachment to the host cell

SARS-CoV-2 has been emerged in December 2019 in China, causing deadly (5% mortality) pandemic pneumonia, termed COVID-19. More than one host-cell receptor is reported to be recognized by the viral spike protein, among them is the cell-surface Heat Shock Protein A5 (HSPA5), also termed GRP78 or BiP. Upon viral infection, HSPA5 is upregulated, then translocating to the cell membrane where it is subjected to be recognized by the SARS-CoV-2 spike. In this study, some natural product compounds are tested against the HSPA5 substrate-binding domain β (SBDβ), which reported to be the recognition site for the SARS-CoV-2 spike. Molecular docking and molecular dynamics simulations are used to test some natural compounds binding to HSPA5 SBDβ. The results show high to a moderate binding affinity for the phytoestrogens (Diadiazin, Genistein, Formontein, and Biochanin A), chlorogenic acid, linolenic acid, palmitic acid, caffeic acid, caffeic acid phenethyl ester, hydroxytyrosol, cis-p-Coumaric acid, cinnamaldehyde, thymoquinone, and some physiological hormones such as estrogens, progesterone, testosterone, and cholesterol to the HSPA5 SBDβ. Based on its binding affinities, the phytoestrogens and estrogens are the best in binding HSPA5, hence may interfere with SARS-CoV-2 attachment to the stressed cells. These compounds can be successful as anti-COVID-19 agents for people with a high risk of cell stress like elders, cancer patients, and front-line medical staff.Communicated by Ramaswamy H. Sarma.

Anti-SARS-CoV-2 Natural Products as Potentially Therapeutic Agents

Severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2), a β-coronavirus, is the cause of the recently emerged pandemic and worldwide outbreak of respiratory disease. Researchers exchange information on COVID-19 to enable collaborative searches. Although there is as yet no effective antiviral agent, like tamiflu against influenza, to block SARS-CoV-2 infection to its host cells, various candidates to mitigate or treat the disease are currently being investigated. Several drugs are being screened for the ability to block virus entry on cell surfaces and/or block intracellular replication in host cells. Vaccine development is being pursued, invoking a better elucidation of the life cycle of the virus. SARS-CoV-2 recognizes O-acetylated neuraminic acids and also several membrane proteins, such as ACE2, as the result of evolutionary switches of O-Ac SA recognition specificities. To provide information related to the current development of possible anti-SARS-COV-2 viral agents, the current review deals with the known inhibitory compounds with low molecular weight. The molecules are mainly derived from natural products of plant sources by screening or chemical synthesis via molecular simulations. Artificial intelligence-based computational simulation for drug designation and large-scale inhibitor screening have recently been performed. Structure-activity relationship of the anti-SARS-CoV-2 natural compounds is discussed.

Is There any Alternative Receptor for SARS-CoV-2?

Angiotensin-converting enzyme II (ACE2) in association with type II transmembrane serine protease (TMPRSS2) is considered the main receptor of SARS-CoV-2. However, considering the clinical complications of COVID-19 in different organs, there is no strong association between the abundance of ACE2/TMPRSS2 co-expression and clinical features of the disease and the severity of complications. Since SARS-CoV-2 affects certain organs that lack or have low expression of ACE2/TMPRSS2, it may be possible that the virus employs other receptors for colonization and entry. Based on recent studies, glucose-regulated protein 78 (GRP78) can be a potential alternative receptor for SARS-CoV-2 entry. In this letter, supporting evidence proposed GRP78 as an alternative receptor in SARS-CoV-2 infection.

The Function of KDEL Receptors as UPR Genes in Disease

The KDEL receptor retrieval pathway is essential for maintaining resident proteins in the endoplasmic reticulum (ER) lumen. ER resident proteins serve a variety of functions, including protein folding and maturation. Perturbations to the lumenal ER microenvironment, such as calcium depletion, can cause protein misfolding and activation of the unfolded protein response (UPR). Additionally, ER resident proteins are secreted from the cell by overwhelming the KDEL receptor retrieval pathway. Recent data show that KDEL receptors are also activated during the UPR through the IRE1/XBP1 signaling pathway as an adaptive response to cellular stress set forth to reduce the loss of ER resident proteins. This review will discuss the emerging connection between UPR activation and KDEL receptors as it pertains to ER proteostasis and disease states.

Identifying Novel Actionable Targets in Colon Cancer

Colorectal cancer is the fourth cause of death from cancer worldwide, mainly due to the high incidence of drug-resistance toward classic chemotherapeutic and newly targeted drugs. In the last decade or so, the development of novel high-throughput approaches, both genome-wide and chemical, allowed the identification of novel actionable targets and the development of the relative specific inhibitors to be used either to re-sensitize drug-resistant tumors (in combination with chemotherapy) or to be synthetic lethal for tumors with specific oncogenic mutations. Finally, high-throughput screening using FDA-approved libraries of “known” drugs uncovered new therapeutic applications of drugs (used alone or in combination) that have been in the clinic for decades for treating non-cancerous diseases (re-positioning or re-purposing approach). Thus, several novel actionable targets have been identified and some of them are already being tested in clinical trials, indicating that high-throughput approaches, especially those involving drug re-positioning, may lead in a near future to significant improvement of the therapy for colon cancer patients, especially in the context of a personalized approach, i.e., in defined subgroups of patients whose tumors carry certain mutations.

Virtual Screening of Phytochemicals by Targeting HR1 Domain of SARS-CoV-2 S Protein: Molecular Docking, Molecular Dynamics Simulations, and DFT Studies

The recent COVID-19 pandemic has impacted nearly the whole world due to its high morbidity and mortality rate. Thus, scientists around the globe are working to find potent drugs and designing an effective vaccine against COVID-19. Phytochemicals from medicinal plants are known to have a long history for the treatment of various pathogens and infections; thus, keeping this in mind, this study was performed to explore the potential of different phytochemicals as candidate inhibitors of the HR1 domain in SARS-CoV-2 spike protein by using computer-aided drug discovery methods. Initially, the pharmacological assessment was performed to study the drug-likeness properties of the phytochemicals for their safe human administration. Suitable compounds were subjected to molecular docking to screen strongly binding phytochemicals with HR1 while the stability of ligand binding was analyzed using molecular dynamics simulations. Quantum computation-based density functional theory (DFT) analysis was constituted to analyze the reactivity of these compounds with the receptor. Through analysis, 108 phytochemicals passed the pharmacological assessment and upon docking of these 108 phytochemicals, 36 were screened passing a threshold of -8.5 kcal/mol. After analyzing stability and reactivity, 5 phytochemicals, i.e., SilybinC, Isopomiferin, Lycopene, SilydianinB, and Silydianin are identified as novel and potent candidates for the inhibition of HR1 domain in SARS-CoV-2 spike protein. Based on these results, it is concluded that these compounds can play an important role in the design and development of a drug against COVID-19, after an exhaustive in vitro and in vivo examination of these compounds, in future.

Glucose-regulated protein (GRP78) is an important cell surface receptor for viral invasion, cancers, and neurological disorders

The 78 kDa glucose-regulated protein (GRP78) is an endoplasmic reticulum (ER)-resident molecular chaperone. GRP78 is a member of the 70 kDa heat shock family of proteins involved in correcting and clearing misfolded proteins in the ER. In response to cellular stress, GRP78 escapes from the ER and moves to the plasma membrane where it (a) functions as a receptor for many ligands, and (b) behaves as an autoantigen for autoantibodies that contribute to human disease and cancer. Cell surface GRP78 (csGRP78) associates with the major histocompatibility complex class I (MHC-I), and is the port of entry for several viruses, including the predictive binding of the novel SARS-CoV-2. Furthermore, csGRP78 is found in association with partners as diverse as the teratocarcinoma-derived growth factor 1 (Cripto), the melanocortin-4 receptor (MC4R) and the DnaJ-like protein MTJ-1. CsGRP78 also serves as a receptor for a large variety of ligands including activated α₂ -macroglobulin (α₂ M*), plasminogen kringle 5 (K5), microplasminogen, the voltage-dependent anion channel (VDAC), tissue factor (TF), and the prostate apoptosis response-4 protein (Par-4). In this review, we discuss the mechanisms involved in the translocation of GRP78 from the ER to the cell surface, and the role of secreted GRP78 and its autoantibodies in cancer and neurological disorders.

Transcriptional Profiling of Porcine Blastocysts Produced In Vitro in a Chemically Defined Culture Medium

The development of chemically defined media is a growing trend in in vitro embryo production (IVP). Recently, traditional undefined culture medium with bovine serum albumin (BSA) has been successfully replaced by a chemically defined medium using substances with embryotrophic properties such as platelet factor 4 (PF4). Although the use of this medium sustains IVP, the impact of defined media on the embryonic transcriptome has not been fully elucidated. This study analyzed the transcriptome of porcine IVP blastocysts, cultured in defined (PF4 group) and undefined media (BSA group) by microarrays. In vivo-derived blastocysts (IVV group) were used as a standard of maximum embryo quality. The results showed no differentially expressed genes (DEG) between the PF4 and BSA groups. However, a total of 2780 and 2577 DEGs were detected when comparing the PF4 or the BSA group with the IVV group, respectively. Most of these genes were common in both in vitro groups (2132) and present in some enriched pathways, such as cell cycle, lysosome and/or metabolic pathways. These results show that IVP conditions strongly affect embryo transcriptome and that the defined culture medium with PF4 is a guaranteed replacement for traditional culture with BSA.

Regulation of RNA Polymerase II Transcription Initiation and Elongation by Transcription Factor TFII-I

Transcription by RNA polymerase II (Pol II) is regulated by different processes, including alterations in chromatin structure, interactions between distal regulatory elements and promoters, formation of transcription domains enriched for Pol II and co-regulators, and mechanisms involved in the initiation, elongation, and termination steps of transcription. Transcription factor TFII-I, originally identified as an initiator (INR)-binding protein, contains multiple protein–protein interaction domains and plays diverse roles in the regulation of transcription. Genome-wide analysis revealed that TFII-I associates with expressed as well as repressed genes. Consistently, TFII-I interacts with co-regulators that either positively or negatively regulate the transcription. Furthermore, TFII-I has been shown to regulate transcription pausing by interacting with proteins that promote or inhibit the elongation step of transcription. Changes in TFII-I expression in humans are associated with neurological and immunological diseases as well as cancer. Furthermore, TFII-I is essential for the development of mice and represents a barrier for the induction of pluripotency. Here, we review the known functions of TFII-I related to the regulation of Pol II transcription at the stages of initiation and elongation.

No evidence of the unfolded protein response in the placenta of two rodent models of preeclampsia and intrauterine growth restriction

In humans, intrauterine growth restriction (IUGR) and preeclampsia (PE) are associated with induction of the unfolded protein response (UPR) and increased placental endoplasmic reticulum (ER) stress. Especially in PE, oxidative stress occurs relative to the severity of maternal vascular underperfusion (MVU) of the placental bed. On the premise that understanding the mechanisms of placental dysfunction could lead to targeted therapeutic options for human IUGR and PE, we investigated the roles of the placental UPR and oxidative stress in two rodent models of these human gestational pathologies. We employed a rat IUGR model of gestational maternal protein restriction, as well as an endothelial nitric oxide synthase knockout mouse model (eNOS-/-) of PE/IUGR. Placental expression of UPR members was analyzed via qRT-PCR (Grp78, Calnexin, Perk, Chop, Atf6, and Ern1), immunohistochemistry, and Western blotting (Calnexin, ATF6, GRP78, CHOP, phospho-eIF2α, and phospho-IRE1). Oxidative stress was determined via Western blotting (3-nitrotyrosine and 4-hydroxy-2-nonenal). Both animal models showed a significant reduction of fetal and placental weight. These effects did not induce placental UPR. In contrast to human data, results from our rodent models suggest retention of placental plasticity in the setting of ER stress under an adverse gestational environment. Oxidative stress was significantly increased only in female IUGR rat placentas, suggesting a sexually dimorphic response to maternal malnutrition. Our study advances understanding of the involvement of the placental UPR in IUGR and PE. Moreover, it emphasizes the appropriate choice of animal models researching various aspects of these pregnancy complications.

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.

Antiviral activity of green tea and black tea polyphenols in prophylaxis and treatment of COVID-19: A review

BACKGROUND

The rapid spread of novel coronavirus called SARS-CoV-2 or nCoV has caused countries all over the world to impose lockdowns and undertake stringent preventive measures. This new positive-sense single-stranded RNA strain of coronavirus spreads through droplets of saliva and nasal discharge.

PURPOSE

US FDA has authorized the emergency use of Remdesivir looking at the increasing number of cases of COVID-19, however there is still no drug approved to treat COVID-19. An alternative way of treatment could be the use of naturally derived molecules with known antiviral properties.

METHOD

We reviewed the antiviral activities of two polyphenols derived from tea, epigallocatechin-3-gallate (EGCG) from green tea and theaflavins from black tea. Both green tea and black tea polyphenols have been reported to exhibit antiviral activities against various viruses, especially positive-sense single-stranded RNA viruses.

RESULTS

Recent studies have revealed the possible binding sites present on SARS-CoV-2 and studied their interactions with tea polyphenols. EGCG and theaflavins, especially theaflavin-3,3'-digallate (TF3) have shown a significant interaction with the receptors under consideration in this review. Some docking studies further emphasize on the activity of these polyphenols against COVID-19.

CONCLUSION

This review summarizes the available reports and evidences which support the use of tea polyphenols as potential candidates in prophylaxis and treatment of COVID-19.

Functional roles of GRP78 in hepatitis B virus infectivity and antigen secretion

Viruses utilize cellular proteins to mediate their life cycle. However, the hepatitis B virus (HBV) life cycle is still mysterious and remains to be elucidated. Here, GRP78/BiP/HSPA5, a 78 kDa glucose-regulated protein, was identified as a preS2 interacting protein. Pulldown assay showed the interaction of glucose-regulated protein 78 (GRP78) with both the preS2 domain-containing large S and middle S proteins expressed in a human hepatocellular cell line. The immunofluorescence studies revealed that the preS2 colocalized with GRP78. Interestingly, it was found that preS2 specifically bound to the ATPase domain of GRP78. To understand how GRP78 plays a role in HBV infection, stably GRP78-expressing cells were established, which promoted HBV infectivity and replication. In contrast, knockdown of GRP78 changed the HBV antigen secretion but not the viral DNA amplification. Taken together, these results suggest that GRP78 should interact with preS2 via the ATPase domain and modulate both the HBV infectivity and HBV antigen secretion.

Expression of the Endoplasmic Reticulum Stress Marker GRP78 in the Normal Retina and Retinal Degeneration Induced by Blue LED Stimuli in Mice

Retinal degeneration is a leading cause of blindness. The unfolded protein response (UPR) is an endoplasmic reticulum (ER) stress response that affects cell survival and death and GRP78 forms a representative protective response. We aimed to determine the exact localization of GRP78 in an animal model of light-induced retinal degeneration. Dark-adapted mice were exposed to blue light-emitting diodes and retinas were obtained at 24 h and 72 h after exposure. In the normal retina, we found that GRP78 was rarely detected in the photoreceptor cells while it was expressed in the perinuclear space of the cell bodies in the inner nuclear and ganglion cell layers. After injury, the expression of GRP78 in the outer nuclear and inner plexiform layers increased in a time-dependent manner. However, an increased GRP78 expression was not observed in damaged photoreceptor cells in the outer nuclear layer. GRP78 was located in the perinuclear space and ER lumen of glial cells and the ER developed in glial cells during retinal degeneration. These findings suggest that GRP78 and the ER response are important for glial cell activation in the retina during photoreceptor degeneration.

Obesity as a Risk Factor for Severe COVID-19 and Complications: A Review

Emerging data suggest that obesity is a major risk factor for the progression of major complications such as acute respiratory distress syndrome (ARDS), cytokine storm and coagulopathy in COVID-19. Understanding the mechanisms underlying the link between obesity and disease severity as a result of SARS-CoV-2 infection is crucial for the development of new therapeutic interventions and preventive measures in this high-risk group. We propose that multiple features of obesity contribute to the prevalence of severe COVID-19 and complications. First, viral entry can be facilitated by the upregulation of viral entry receptors, like angiotensin-converting enzyme 2 (ACE2), among others. Second, obesity-induced chronic inflammation and disruptions of insulin and leptin signaling can result in impaired viral clearance and a disproportionate or hyper-inflammatory response, which together with elevated ferritin levels can be a direct cause for ARDS and cytokine storm. Third, the negative consequences of obesity on blood coagulation can contribute to the progression of thrombus formation and hemorrhage. In this review we first summarize clinical findings on the relationship between obesity and COVID-19 disease severity and then further discuss potential mechanisms that could explain the risk for major complications in patients suffering from obesity.

ILDR2 stabilization is regulated by its interaction with GRP78

Ildr2 was initially identified as a genetic modifier of diabetes susceptibility in B6.DBA Lep^ob congenic mice, and was associated with decreased β-cell replication rates, reduced β-cell mass, and persistent mild hypoinsulinemic hyperglycemia. However, the molecular mechanisms of how the ILDR2 protein is involved in these effects are largely unknown. We sought to identify ILDR2-interacting proteins to further elucidate the molecular mechanisms underpinning ILDR2 function in pancreatic β-cells. Using TAP tag technology, we purified proteins interacting with ILDR2 in the pancreatic β-cell line MIN6, and identified the endoplasmic reticulum resident chaperones, GRP78 and PDIA1, as novel proteins interacting with ILDR2. We demonstrated that GRP78 interacted with ILDR2 and was possibly involved in ILDR2 stabilization by inhibiting ubiquitin–proteasome degradation. Additionally, adenoviral ILDR2 knockdown led to reduced glucose-responsive insulin secretion in MIN6 β-cells, suggesting ILDR2 may be implicated in a new pathway in hypoinsulinemic hyperglycemia. These data provide evidence for a novel association between GRP78 and ILDR2, and suggest GPR78-ILDR2 may a novel target for diabetic therapeutic modulation in decreased insulin secretion.

Dexmedetomidine Attenuates Ischemia/Reperfusion-Induced Myocardial Inflammation and Apoptosis Through Inhibiting Endoplasmic Reticulum Stress Signaling

Background

Endoplasmic reticulum stress (ERS)-mediated myocardial inflammation and apoptosis plays an important role in myocardial ischemia/reperfusion (I/R) injury. Dexmedetomidine has been used clinically with sedative, analgesic, and anti-inflammatory properties. This study aimed to determine the effects of dexmedetomidine pretreatment on inflammation, apoptosis, and the expression of ERS signaling during myocardial I/R injury.

Methods

Rats underwent myocardial ischemia for 30 min and reperfusion for 6 h, and H9c2 cardiomyocytes were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) injury (OGD for 12 h and reoxygenation for 3 h). Dexmedetomidine was administered prior to myocardial ischemia in rats or ODG in cardiomyocytes. In addition, the α2-adrenergic receptor antagonist (yohimbine) or the PERK activator (CCT020312) was given prior to dexmedetomidine treatment.

Results

Dexmedetomidine pretreatment decreased serum levels of cardiac troponin I, reduced myocardial infarct size, alleviated histological structure damage, and improved left ventricular function following myocardial I/R injury in rats. In addition, dexmedetomidine pretreatment increased cell viability and reduced cytotoxicity following OGD/R injury in cardiomyocytes. Mechanistically, the cardioprotection offered by dexmedetomidine was mediated via the inhibition of inflammation and apoptosis through downregulating the expression of the ERS signaling pathway, including glucose-regulated protein 78 (GRP78), protein kinase R-like endoplasmic reticulum kinase (PERK), C/EBP homologous protein (CHOP), inositol-requiring protein 1 (IRE1), and activating transcription factor 6 (ATF6). Conversely, the protective effects of dexmedetomidine were diminished by blocking the α2 adrenergic receptors with yohimbine or promoting PERK phosphorylation with CCT020312.

Conclusion

Dexmedetomidine pretreatment protects the hearts against I/R injury via inhibiting inflammation and apoptosis through downregulation of the ERS signaling pathway. Future clinical studies are needed to confirm the cardioprotective effects of dexmedetomidine in patients at risk of myocardial I/R injury.

Structural and Functional Significance of the Endoplasmic Reticulum Unfolded Protein Response Transducers and Chaperones at the Mitochondria-ER Contacts: A Cancer Perspective

In the last decades, the endoplasmic reticulum (ER) has emerged as a key coordinator of cellular homeostasis, thanks to its physical interconnection to almost all intracellular organelles. In particular, an intense and mutual crosstalk between the ER and mitochondria occurs at the mitochondria–ER contacts (MERCs). MERCs ensure a fine-tuned regulation of fundamental cellular processes, involving cell fate decision, mitochondria dynamics, metabolism, and proteostasis, which plays a pivotal role in the tumorigenesis and therapeutic response of cancer cells. Intriguingly, recent studies have shown that different components of the unfolded protein response (UPR) machinery, including PERK, IRE1α, and ER chaperones, localize at MERCs. These proteins appear to exhibit multifaceted roles that expand beyond protein folding and UPR transduction and are often related to the control of calcium fluxes to the mitochondria, thus acquiring relevance to cell survival and death. In this review, we highlight the novel functions played by PERK, IRE1α, and ER chaperones at MERCs focusing on their impact on tumor development.

The importance of mucormycosis infections on example of Rhino Orbital Cerebral Mucormycosis

Mucormycosis is an angioinvasive fungal infection, characterized by high morbidity and mortality and is strongly dependent on the patient’s general health condition, initial site of infection, and the time from diagnosis to treatment commencement. It has been reported that the occurrence of mucormycosis has increased rapidly, also among immunocompetent patients. Moreover, the rise in number is expected to continue. Among all clinical manifestations of mucormycosis, the rhino-orbital-cerebral type (ROCM) is the most common. The aim of this article is to increase the awareness of mucoral infections, especially ROCM, and to describe its first symptoms, as proper treatment requires immediate surgical and medical intervention.

The molecular mechanism of a novel derivative of BTO-956 induced apoptosis in human myelomonocytic lymphoma cells

Acute myeloid leukemia (AML) is a malignant cancer of the hematopoietic system. Although the effectiveness of arsenic compounds has been recognized and applied clinically, some patients are still found resistant to this chemotherapy. In this study, we investigated that a synthetic thyroid hormone analog (TA), 2-iodo-4-nitro-1-(o-tolyloxy) benzene, had a strong apoptosis effect on U937 cells. U937 cells were treated with TA, and examinted the generation of reactive oxygen species (ROS), dysfunction of mitochondria, expression of pro-apoptosis and anti-apoptosis, and cleavage of caspase-3 and Poly (ADP-ribose) polymerase (PARP). Further, it is also evaluated that insight molecular mechanism and signaling pathways involved in the study. It is found that TA significantly induced apoptosis in U937 cells through production of ROS, dysfunction of mitochondria, and activation of caspase cascade. It was also observed that MAPK signaling pathway including ERK, JNK, and P38 signals are involved in the induction of apoptosis. Moreover, marked activation of autophagy and ER stress markers such as LC3, P62, Beclin1 and GRP78, CHOP were observed, respectively. Pretreatment with ER stress inhibitor tauroursodeoxycholic acid (TUDCA) and autophagy inhibitor 3-Methyladenine (3-MA) have successfully attenuated and aggravated TA-induced apoptosis, respectively. We further confirmed the active involvement of ER stress and autophagy signals. In conclusion, TA induced apoptosis through ER stress and activation of autophagy, and the latter is not conducive to TA-induced cell death. Our results may provide a new insight into the strategic development of novel therapy for the treatment of AML.

Proteomic Discovery of VEEV E2-Host Partner Interactions Identifies GRP78 Inhibitor HA15 as a Potential Therapeutic for Alphavirus Infections

Alphaviruses are a genus of the Togaviridae family and are widely distributed across the globe. Venezuelan equine encephalitis virus (VEEV) and eastern equine encephalitis virus (EEEV), cause encephalitis and neurological sequelae while chikungunya virus (CHIKV) and Sindbis virus (SINV) cause arthralgia. There are currently no approved therapeutics or vaccines available for alphaviruses. In order to identify novel therapeutics, a V5 epitope tag was inserted into the N-terminus of the VEEV E2 glycoprotein and used to identify host-viral protein interactions. Host proteins involved in protein folding, metabolism/ATP production, translation, cytoskeleton, complement, vesicle transport and ubiquitination were identified as VEEV E2 interactors. Multiple inhibitors targeting these host proteins were tested to determine their effect on VEEV replication. The compound HA15, a GRP78 inhibitor, was found to be an effective inhibitor of VEEV, EEEV, CHIKV, and SINV. VEEV E2 interaction with GRP78 was confirmed through coimmunoprecipitation and colocalization experiments. Mechanism of action studies found that HA15 does not affect viral RNA replication but instead affects late stages of the viral life cycle, which is consistent with GRP78 promoting viral assembly or viral protein trafficking.

Unraveling the Molecular Nexus between GPCRs, ERS, and EMT

G protein-coupled receptors (GPCRs) represent a large family of transmembrane proteins that transduce an external stimulus into a variety of cellular responses. They play a critical role in various pathological conditions in humans, including cancer, by regulating a number of key processes involved in tumor formation and progression. The epithelial-mesenchymal transition (EMT) is a fundamental process in promoting cancer cell invasion and tumor dissemination leading to metastasis, an often intractable state of the disease. Uncontrolled proliferation and persistent metabolism of cancer cells also induce oxidative stress, hypoxia, and depletion of growth factors and nutrients. These disturbances lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and induce a cellular condition called ER stress (ERS) which is counteracted by activation of the unfolded protein response (UPR). Many GPCRs modulate ERS and UPR signaling via ERS sensors, IRE1α, PERK, and ATF6, to support cancer cell survival and inhibit cell death. By regulating downstream signaling pathways such as NF-κB, MAPK/ERK, PI3K/AKT, TGF-β, and Wnt/β-catenin, GPCRs also upregulate mesenchymal transcription factors including Snail, ZEB, and Twist superfamilies which regulate cell polarity, cytoskeleton remodeling, migration, and invasion. Likewise, ERS-induced UPR upregulates gene transcription and expression of proteins related to EMT enhancing tumor aggressiveness. Though GPCRs are attractive therapeutic targets in cancer biology, much less is known about their roles in regulating ERS and EMT. Here, we will discuss the interplay in GPCR-ERS linked to the EMT process of cancer cells, with a particular focus on oncogenes and molecular signaling pathways.

Ursolic acid alleviates heat stress-induced lung injury by regulating endoplasmic reticulum stress signaling in mice

Acute lung injury has been reported to be associated with heat stress in various animals. Ursolic acid is a natural pentacyclic triterpenoid compound with multiple bioactivities. However, it remains unknown whether ursolic acid supplementation alleviates heat stress-induced lung injury. In the present study, male Institute of Cancer Research mice were left untreated under a normal temperature condition (23±1°C), receiving orally administrated with vehicle (phosphate buffered saline) or ursolic acid (40 mg/kg BW-1·d-1 for 2 d), and then were subjected to high temperature (41±1°C) for 2 h. Histological alterations, activities of antioxidative enzymes, apoptosis, generation of reactive oxygen species, abundance of inflammatory cytokines, and endoplasmic reticulum stress-related proteins were analyzed. Compared with the controls, heat stress treatment led to enhanced apoptosis, increased H2O2 production, and upregulated protein levels of inflammatory cytokines in the serum, including tumor necrosis factor alpha, interleukin-6, and interleukin-1 beta. Activities of malondialdehyde, lactate dehydrogenase, and myeloperoxidase were increased, while the activities for superoxide dismutase and catalase were reduced in lung tissues of mice. All these alterations were significantly prevented by ursolic acid administration. Further study showed that heat stress led to activation of protein kinase-like ER kinase eukaryotic initiation factor 2 alpha -the transcription factor CCAAT-enhancer-binding protein homologous protein (CHOP) signaling, which was attenuated by ursolic acid supplementation. These findings indicated that ursolic acid pretreatment protected lung tissues against heat stress-induced injury by regulating inflammatory cytokines and unfolded protein response in mice. Ursolic acid supplementation might be a therapeutic strategy to alleviate high temperature-induced lung injury in humans and animals.

The Pathology of Morphine-Inhibited Nerve Repair and Morphine-Induced Nerve Damage Is Mediated via Endoplasmic Reticulum Stress

Objective

The aim of the present study was to observe the pathological damage in the cerebral cortex of rats under acute morphine exposure (AME) and different durations of morphine dependence (MD), explore whether endoplasmic reticulum stress (ERS) is involved in the damage process, and assess the effect of morphine exposure on the proliferation and differentiation of newborn neurons.

Methods

Rat models of AME and different durations of MD were established. Pathological changes in cortical neurons were assessed by hematoxylin and eosin (H&E) and thionine staining. The expression of nuclear receptor-related factor 1 (NURR1) and that of the ERS-related proteins glucose-regulated protein 78 (GRP78), p-eIF2α, activating transcription factor 6 (ATF6), and CHOP in cortical neurons was assessed by immunohistochemistry. Double immunofluorescence labeling was used to observe the expression of Ki-67.

Results

H&E and thionine staining revealed that AME resulted in pyknotic changes in cortical neurons. With prolonged morphine exposure, the number of pyknotic neurons was significantly increased, the protein expression of Ki-67 and NURR1 was significantly decreased, and the protein levels of GRP78, p-eIF2α, ATF6, and CHOP showed marked dynamic changes.

Conclusion

AME and different durations of MD caused varying degrees of pathological changes in the cortex. Furthermore, the dynamic changes observed in ERS-related protein expression suggested that ERS may be associated with cortical injury. Different durations of MD inhibited the proliferation, differentiation, and migration of newborn neurons, which may affect the nerve repair process after injury.

Evaluation and characterization of HSPA5 (GRP78) expression profiles in normal individuals and cancer patients with COVID-19

HSPA5 (BiP, GRP78) has been reported as a potential host-cell receptor for SARS-Cov-2, but its expression profiles on different tissues including tumors, its susceptibility to SARS-Cov-2 virus and severity of its adverse effects on malignant patients are unclear. In the current study, HSPA5 has been found to be expressed ubiquitously in normal tissues and significantly increased in 14 of 31 types of cancer tissues. In lung cancer, mRNA levels of HSPA5 were 253-fold increase than that of ACE2. Meanwhile, in both malignant tumors and matched normal samples across almost all cancer types, mRNA levels of HSPA5 were much higher than those of ACE2. Higher expression of HSPA5 significantly decreased patient overall survival (OS) in 7 types of cancers. Moreover, systematic analyses found that 7.15% of 5,068 COVID-19 cases have malignant cancer coincidental situations, and the rate of severe events of COVID-19 patients with cancers present a higher trend than that for all COVID-19 patients, showing a significant difference (33.33% vs 16.09%, p<0.01). Collectively, these data imply that the tissues with high HSPA5 expression, not low ACE2 expression, are susceptible to be invaded by SARS-CoV-2. Taken together, this study not only indicates the clinical significance of HSPA5 in COVID-19 disease and cancers, but also provides potential clues for further medical treatments and managements of COVID-19 patients.

Sodium 4-Phenylbutyrate Protects Hypoxic-Ischemic Brain Injury via Attenuating Endoplasmic Reticulum Stress in Neonatal Rats

Neonatal hypoxic-ischemic (HI) brain injury is associated with long-term neurological disorders, and protective strategies are presently scarce. Sodium 4-phenylbutyrate (4-PBA) reportedly acts as a chemical chaperone that alleviates endoplasmic reticulum (ER) stress, which plays a critical role in neurological diseases. The present study aimed to evaluate the neuroprotective effects of 4-PBA on HI-induced neonatal brain injury in a rat model, and to characterize possible underlying mechanisms. The HI brain injury model was established by ligating the left common carotid artery in 7-day-old rats, followed by exposure to 8% oxygen for 2 h. The 4-PBA or vehicle was administered by an intracerebroventricular injection 30 min before HI. The protein expression levels of ER stress markers (GRP78, ATF6, and CHOP) were detected by western blotting at 24 h after HI insult. The activation of cAMP-response element-binding protein (CREB) was evaluated by western blotting and immunofluorescence. TUNEL and Nissl staining were performed to detect the histomorphological changes in the hippocampal neurons at 24 h and 7 days, respectively, after HI injury. From days 29 to 34 after brain HI, rats underwent Morris water maze tests to assess cognitive functioning. The results showed that pretreatment with 4-PBA decreased HI-induced excessive ER stress and neuronal injury. Moreover, CREB activation might be involved in the beneficial effects of 4-PBA on HI-induced learning and memory deficits in rats. In conclusion, the present study suggested a potential therapeutic approach of ER stress inhibition in the treatment of neonatal HI brain injury.