Effect of pharmaceutical potential endocrine disruptor compounds on protein disulfide isomerase reductase activity using di-eosin-oxidized-glutathione

Functions and mechanisms of protein disulfide isomerase family in cancer emergence

The endoplasmic reticulum (ER) is a multi-layered organelle that is essential for the synthesis, folding, and structural maturation of almost one-third of the cellular proteome. It houses several resident proteins for these functions including the 21 members of the protein disulfide isomerase (PDI) family. The signature of proteins belonging to this family is the presence of the thioredoxin domain which mediates the formation, and rearrangement of disulfide bonds of substrate proteins in the ER. This process is crucial not only for the proper folding of ER substrates but also for maintaining a balanced ER proteostasis. The inclusion of new PDI members with a wide variety of structural determinants, size and enzymatic activity has brought additional epitomes of how PDI functions. Notably, some of them do not carry the thioredoxin domain and others have roles outside the ER. This also reflects that PDIs may have specialized functions and their functions are not limited within the ER. Large-scale expression datasets of human clinical samples have identified that the expression of PDI members is elevated in pathophysiological states like cancer. Subsequent functional interrogations using structural, molecular, cellular, and animal models suggest that some PDI members support the survival, progression, and metastasis of several cancer types. Herein, we review recent research advances on PDIs, vis-à-vis their expression, functions, and molecular mechanisms in supporting cancer growth with special emphasis on the anterior gradient (AGR) subfamily. Last, we posit the relevance and therapeutic strategies in targeting the PDIs in cancer.

Current advancements on the fabrication, modification, and industrial application of zinc oxide as photocatalyst in the removal of organic and inorganic contaminants in aquatic systems

Industrial wastewaters contain hazardous contaminants that pollute the environment and cause socioeconomic problems, thus demanding the employment of effective remediation procedures such as photocatalysis. Zinc oxide (ZnO) nanomaterials have emerged to be a promising photocatalyst for the removal of pollutants in wastewater owing to their excellent and attractive characteristics. The dynamic tunable features of ZnO allow a wide range of functionalization for enhanced photocatalytic efficiency. The current review summarizes the recent advances in the fabrication, modification, and industrial application of ZnO photocatalyst based on the analysis of the latest studies, including the following aspects: (1) overview on the properties, structures, and features of ZnO, (2) employment of dopants, heterojunction, and immobilization techniques for improved photodegradation performance, (3) applicability of suspended and immobilized photocatalytic systems, (4) application of ZnO hybrids for the removal of various types of hazardous pollutants from different wastewater sources in industries, and (5) potential of bio-inspired ZnO hybrid nanomaterials for photocatalytic applications using renewable and biodegradable resources for greener photocatalytic technologies. In addition, the knowledge gap in this field of work is also highlighted.

Effects of quetiapine administration on sperm quality and testicular histology

Quetiapine is one of the most commonly prescribed antipsychotics to treat schizophrenia in adults, in particular. In this study, quetiapine's effects were assessed on healthy sperm production in rats at repeated-pharmacological doses. Additionally, the effects of quetiapine on oxidative status and hormonal balance were also evaluated in rats. Quetiapine was administered to rats orally at 10, 20, and 40 mg/kg body weight doses for 28 days. At the end of this period, body and organ weights were measured, sperm concentration, motility, and morphology were determined, sperm damage was assessed, and histopathological analysis of testicular tissue was performed. Additionally, serum FSH, LH, and testosterone levels as male reproductive hormones were measured. Catalase, superoxide dismutase, glutathione, and malondialdehyde levels were determined for evaluating the oxidative status of testicular tissue. The findings obtained in this study showed that relative epididymis weights and sperm concentration decreased and abnormal sperm morphology increased in quetiapine-administered rats. Irregularity of typical architecture of the seminiferous tubules and germinal cell disorganization was observed in testicular sections of 20 and 40 mg/kg quetiapine-administered rats. Further, serum LH and testosterone levels decreased in 20 and 40 mg/kg quetiapine-administered rats. Additionally, decreased catalase and superoxide dismutase activities in testicular tissue of quetiapine-administered rats and increased malondialdehyde levels in testicular tissue of 40 mg/kg quetiapine-administered rats were measured. In conclusion, quetiapine treatment decreased sperm quality, altered hormone levels, and induced oxidative stress may be considered potential contributors to this adverse effect.

Lung epithelial protein disulfide isomerase A3 (PDIA3) plays an important role in influenza infection, inflammation, and airway mechanics

Protein disulfide isomerases (PDI) are a family of redox chaperones that catalyze formation or isomerization of disulfide bonds in proteins. Previous studies have shown that one member, PDIA3, interacts with influenza A virus (IAV) hemagglutinin (HA), and this interaction is required for efficient oxidative folding of HA in vitro. However, it is unknown whether these host-viral protein interactions occur during active infection and whether such interactions represent a putative target for the treatment of influenza infection. Here we show that PDIA3 is specifically upregulated in IAV-infected mouse or human lung epithelial cells and PDIA3 directly interacts with IAV-HA. Treatment with a PDI inhibitor, LOC14 inhibited PDIA3 activity in lung epithelial cells, decreased intramolecular disulfide bonds and subsequent oligomerization (maturation) of HA in both H1N1 (A/PR8/34) and H3N2 (X31, A/Aichi/68) infected lung epithelial cells. These reduced disulfide bond formation significantly decreased viral burden, and also pro-inflammatory responses from lung epithelial cells. Lung epithelial-specific deletion of PDIA3 in mice resulted in a significant decrease in viral burden and lung inflammatory-immune markers upon IAV infection, as well as significantly improved airway mechanics. Taken together, these results indicate that PDIA3 is required for effective influenza pathogenesis in vivo, and pharmacological inhibition of PDIs represents a promising new anti-influenza therapeutic strategy during pandemic and severe influenza seasons.

Succination of Protein Disulfide Isomerase Links Mitochondrial Stress and Endoplasmic Reticulum Stress in the Adipocyte During Diabetes

AIMS

Protein succination by fumarate increases in the adipose tissue of diabetic mice and in adipocytes matured in high glucose as a result of glucotoxicity-driven mitochondrial stress. The endoplasmic reticulum (ER) oxidoreductase protein disulfide isomerase (PDI) is succinated in adipocytes that are matured in high glucose, and in this study we investigated whether succination would alter PDI oxidoreductase activity, directly linking mitochondrial stress and ER stress.

RESULTS

Protein succination and the ER stress marker C/EBP homologous protein (CHOP) were diminished after pharmaceutical targeting of mitochondrial stress with the chemical uncoupler niclosamide in adipocytes matured in high-glucose concentrations. PDI was succinated by fumarate on both CXXC-containing active sites, contributing to reduced enzymatic activity. Succinated PDI decreased reductase activity in adipocytes matured in high glucose, and in db/db epididymal adipose tissue, in association with increased levels of CHOP. PDI succination was increased in fumarase knockdown adipocytes, leading to reduced PDI oxidoreductase activity, increased CHOP levels, and pro-inflammatory cytokine secretion, confirming the specific role of elevated fumarate levels in contributing to ER stress. In addition, PDI succination and ER stress were decreased, and PDI reductase activity was restored when exposure to chronic high glucose was limited, highlighting the importance of calorie restriction in the improvement of adipocyte metabolic function.

INNOVATION

These experiments identify PDI succination as a novel biochemical mechanism linking altered mitochondrial metabolism to ER stress in the adipocyte during diabetes.

CONCLUSION

The current study demonstrates that early biochemical changes in mitochondrial metabolism have important implications for the development of adipocyte stress. Antioxid. Redox Signal. 27, 1281-1296.

Tanshinone IIA increases levels of NeuN, protein disulfide isomerase, and Na+/K+-ATPase and decreases evidence of microglial activation after cerebral ischemic injury

This study was designed to clarify the neuroprotective effects of tanshinone IIA (TSA) following cerebral ischemic insult. Adult Sprague-Dawley rats were operated upon to achieve a middle cerebral artery occlusion to cause transient focal cerebral ischemia, which were then randomly divided into the sham-operated control group and cerebral ischemia/reperfusion (I/R) groups receiving a 2 h occlusion. The treatment groups received daily intraperitoneal injections of high or low doses of TSA, for 7 or 15 days. NeuN immunostaining revealed neuronal loss following I/R, which was partially prevented with subsequent TSA dosing. Protein disulfide isomerase and adenosine triphosphatase (Na(+)/K(+)-ATPase) levels were all depressed by means of I/R. TSA treatment markedly reversed the depression of all indices examined. The intensity of microglial activation, as evidenced with CD11b staining, was increased by means of cerebral artery occlusion, but this was partially reversed with subsequent TSA treatment. TSA may affect neuroprotection by way of minimizing deficits in energy metabolism and reduction of the extent of cell death within affected regions.

The X awakens: multifactorial ramifications of sex-specific differences in HIV-1 infection

Sex-specific differences have been described for a variety of infectious and autoimmune diseases. In HIV-1 infection women present with significantly lower viral loads during early infection, but during chronic infection women progress faster to AIDS for the same amount of viral replication. Recent studies have shown that sex differences during HIV-1 infection might also include the size of the latent viral reservoir, which represents a major obstacle towards a cure for HIV-1. Here we review different immunological and virological aspects that can be influenced by sex hormones and sex-specific genetic factors and their contribution to viral replication, as well as the creation and maintenance of the HIV-1 reservoir.

Characterization of the estradiol-binding site structure of human protein disulfide isomerase (PDI)

Background

Earlier studies showed that 17β-estradiol (E₂), an endogenous female sex hormone, can bind to human protein disulfide isomerase (PDI), a protein folding catalyst for disulfide bond formation and rearrangement. This binding interaction can modulate the intracellular levels of E₂ and its biological actions. However, the structure of PDI's E₂-binding site is still unclear at present, which is the focus of this study.

Methodology/Principal Findings

The E₂-binding site structure of human PDI was studied by using various biochemical approaches coupled with radiometric receptor-binding assays, site-directed mutagenesis, and molecular computational modeling. Analysis of various PDI protein fragments showed that the [³H]E₂-binding activity is not associated with the single b or b' domain but is associated with the b-b' domain combination. Computational docking analyses predicted that the E₂-binding site is located in a hydrophobic pocket composed mainly of the b' domain and partially of the b domain. A hydrogen bond, formed between the 3-hydroxyl group of E₂ and His256 of PDI is critical for the binding interaction. This binding model was jointly confirmed by a series of detailed experiments, including site-directed mutagenesis of the His256 residue coupled with selective modifications of the ligand structures to alter the binding interaction.

Conclusions/Significance

The results of this study elucidated the structural basis for the PDI–E₂ binding interaction and the reservoir role of PDI in modulating the intracellular E₂ levels. The identified PDI E₂-binding site is quite different from its known peptide binding sites. Given that PDI is a potential therapeutic target for cancer chemotherapy and HIV prevention and that E₂ can inhibit PDI activity in vitro, the E₂-binding site structure of human PDI determined here offers structural insights which may aid in the rational design of novel PDI inhibitors.

Potentiation of the reductase activity of protein disulphide isomerase (PDI) by 19-nortestosterone, bacitracin, fluoxetine, and ammonium sulphate

Protein disulphide isomerase (PDI) in the endoplasmic reticulum catalyzes the rearrangement of disulphide bridges during folding of secreted proteins. It binds various molecules that inhibit its activity. But here, we looked for molecules that would potentiate its activity. PDI reductase activity was measured in vitro using di-eosin-oxidized glutathione as substrate. Its classical inhibitor bacitracin was found to exert a biphasic effect: stimulatory at low concentrations (∼10(-6) M) and inhibitory only at higher concentrations (∼10(-4)-10(-3) M). The weak oestrogenic molecule bisphenol A was found to exert a weak inhibitory effect on PDI reductase activity relative to the strong oestrogens, ethynylestradiol, and diethylstilbestrol. Like 19-nortestosterone, fluoxetine was found to exert a potentiating effect on PDI reductase activity and their potentiating effects could be reversed by increasing concentrations of oestrogens. In conclusion, this paper provides the first identification of potentiators of PDI activity that are potential pharmaceuticals against pathologies affecting protein folding such as Alzheimer's disease.