A Neuroprotective Dose of Isatin Causes Multilevel Changes Involving the Brain Proteome: Prospects for Further Research

Biological Activity Evaluation of Phenolic Isatin-3-Hydrazones Containing a Quaternary Ammonium Center of Various Structures

A series of new isatin-3-hydrazones bearing different ammonium fragments was synthesized by a simple and easy work-up reaction of Girard's reagents analogs with 1-(3,5-di-tert-butyl-4-hydroxybenzyl)isatin. All derivatives have been shown to have antioxidant properties. In terms of bactericidal activity against gram-positive bacteria, including methicillin-resistant strains of Staphylococcus aureus, the best compounds are 3a, 3e, and 3m, bearing octyl, acetal, and brucine ammonium centers, respectively. In addition, brucine and quinine derivatives 3l, and 3j exhibit platelet antiaggregation activity at the level of acetylsalicylic acid, and this series of isatin derivatives does not adversely affect the hemostasis system as a whole. Thus, all the obtained results can lay the groundwork for future pharmaceutical developments for the creation of effective antibacterial drugs with reduced systemic toxicity due to the presence of antioxidant properties.

The neuroprotective effect of isatin in the rotenone-induced model of parkinonism in rats: the study of delayed effects

Parkinsonism in rats induced by the pesticide rotenone is one of the most adequate models of Parkinson's disease (PD). Isatin (indole-2,3-dione) is an endogenous regulator found in mammals and humans and exhibiting a wide range of biological activities mediated by numerous isatin-binding proteins, including those associated with neurodegenerative pathology. A course of rotenone administration to rats caused behavioral impairments and changes in the profile and relative content of isatin-binding proteins in the brain. In this study, we have investigated the delayed neuroprotective effect of isatin (5 days after completion of the course of rotenone administration) on behavioral reactions and the relative content of isatin-binding proteins in the brain of rats with rotenone-induced experimental parkinsonism. Although during this period the rats retained locomotor dysfunction, the proteomic analysis data (profile of isatin-binding proteins in the brain and changes in their relative content) differed from the results obtained immediately after completion of the course of rotenone administration. Moreover, all isatin-binding proteins with altered relative content changed during this period are associated to varying degrees with neurodegeneration (many with Parkinson's and Alzheimer's diseases).

Sevoflurane Alters Serum Metabolites in Elders and Aging Mice and Increases Inflammation in Hippocampus

Purpose

Postoperative cognitive dysfunction (POCD) is a central nervous system complication that occurs after anesthesia, particularly among the elderly. However, the neurological pathogenesis of postoperative cognitive dysfunction remains unclear. The aim of this study was to evaluate the effects of sevoflurane exposure on serum metabolites and hippocampal gene expression in elderly patients and aging mice by metabolomics and transcriptomic analysis and to explore the pathogenesis of sevoflurane induced POCD.

Patients and Methods

Human serum samples from five patients over 60 years old were collected before sevoflurane anesthesia and 1 hour after anesthesia. Besides, mice aged at 12 months (n=6 per group) were anesthetized with sevoflurane for 2 hours or with sham procedure. Subsequently, serum and hippocampal tissues were harvested for analysis. Further investigation into the relationship between isatin and neuroinflammation was conducted using BV2 microglial cells.

Results

Sevoflurane anesthesia led to the activation of inflammatory pathways, an increased presence of hippocampal astrocytes and microglia, and elevated expression of neuroinflammatory cytokines. Comparative analysis identified 12 differential metabolites that exhibited changes in both human and mouse serum post-sevoflurane anesthesia. Notably, isatin levels were significantly decreased after anesthesia. Notably, isatin levels significantly decreased after anesthesia, a factor known to stimulate proliferation and proinflammatory gene expression in microglia-the pivotal cell type in inflammatory responses.

Conclusion

Sevoflurane-induced alterations in serum metabolites in both elderly patients and aging mice, subsequently contributing to increased inflammation in the hippocampus.

The delayed effect of rotenone on the relative content of brain isatin-binding proteins of rats with experimental parkinsonism

Isatin (indoldione-2,3) is an endogenous biological regulator found in the brain, peripheral tissues, and biological fluids of humans and animals. Its biological activity is realized via isatin-binding proteins, many of which were identified during proteomic profiling of the brain of mice and rats. A number of these proteins are related to the development of neurodegenerative diseases. Previously, using a model of experimental Parkinsonism induced by a seven-day course of rotenone injections, we have observed behavioral disturbances, as well as changes in the profile and relative content of brain isatin-binding proteins. In this study, we have investigated behavioral responses and the relative content of brain isatin-binding proteins in rats with rotenone-induced Parkinsonism 5 days after the last administration of this neurotoxin. Despite the elimination of rotenone, animals exhibited motor and coordination impairments. Proteomic profiling of isatin-binding proteins revealed changes in the relative content of 120 proteins (the relative content of 83 proteins increased and that of 37 proteins decreased). Comparison of isatin-binding proteins characterized by the changes in the relative content observed in the brain right after the last injection of rotenone (n=16) and 5 days later (n=11) revealed only two common proteins (glyceraldehyde-3-phosphate dehydrogenase and subunit B of V-type proton ATPase). However, most of these proteins are associated with neurodegeneration, including Parkinson's and Alzheimer's diseases.

Neuroprotective effects of isatin and afobazole in rats with rotenone-induced Parkinsonism are accompanied by increased brain levels of Triton X-100 soluble alpha-synuclein

Effects of the endogenous neuroprotector isatin and the pharmacological drug afobazole (exhibiting neuroprotective properties) on behavioral reactions and quantitative changes in the brain proteomic profile have been investigated in rats with experimental rotenone Parkinsonism. A single dose of isatin (100 mg/kg subcutaneously on the last day of a 7-day course of rotenone administration) improved the motor activity of rats with rotenone-induced Parkinsonism in the open field test (horizontal movements) and the rotating rod test. Afobazole (10 mg/kg intraperitoneally, daily during the 7-day course of rotenone administration) reduced the manifestations of rigidity and postural instability. Proteomic analysis, performed using brain samples obtained the day after the last administration of rotenone and neuroprotectors, revealed similar quantitative changes in the brain of rats with rotenone Parkinsonism. An increase in the relative content of 65 proteins and a decrease in the relative content of 21 proteins were detected. The most pronounced changes - an almost ninety-fold increase in the alpha-synuclein content - were found in the brains of rats treated with isatin. In animals of the experimental groups treated with "Rotenone + Isatin", as well as "Rotenone + Afobazole", the increase in the relative content of this protein in the brain was almost 60 and 50 times higher than the control values. Taking into consideration the known data on the physiological role of alpha-synuclein, an increase in the content of this protein in the brain upon administration of neuroprotectors to animals with rotenone Parkinsonism may represent a compensatory reaction, at least in the early stages of this disease and the beginning of its treatment.

Design, synthesis, molecular docking and DFT studies on novel melatonin and isatin based azole derivatives

In order to address the pressing demand for newer broad-spectrum antifungal medicines with enhanced activity, computer modelling was utilised to rationally develop newer antifungal azole-based drugs. Based on the drug and active sites of the Lanosterol 14 alpha-Demethylases (LAD) of the prominent fungal pathogen Candida albicans interaction, Novel triazole-linked melatonin and isatin derivatives 7a-d and 8a-d were synthesised using bioisosterism. Besides the experimental synthesis and subsequent characterization, the present study focused on obtaining optimised geometries, frequency calculations, and TD-DFT studies of the synthesised molecules. We also performed molecular docking studies to explore the inhibitory ability of the synthesised compounds against the active sites of the Lanosterol 14 alpha-Demethylases (LAD) of the prominent fungal pathogen Candida albicans. The binding interactions resulted in positive findings, demonstrating the involvement of the synthesised compounds in the suppression of fungal growth. Comparative analysis of the binding potential of the synthesised molecules and commercially available drug fluconazole revealed a remarkable note: the docking scores for the designed drugs 7b, 7c, and 8c are much greater than those of the fluconazole molecule. The in silico study of the designed series of drug molecules serves as an important guideline for further exploration in the quest for potent antifungal agents.

Quantitative changes of brain isatin-binding proteins of rats with the rotenone-induced experimental parkinsonism

Isatin (indoldione-2,3) is an endogenous regulator found in humans and animals. It exhibits a broad range of biological activity mediated by numerous isatin-binding proteins. Isatin produces neuroprotective effects in several experimental models of diseases, including Parkinsonism induced by the neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine).Rotenone (a neurotoxin used to modeling Parkinson's disease in rodents) causes significant changes in the profile of isatin-binding proteins of rat brain. Comparative proteomic identification of brain proteins of control rats and the rats with the rotenone-induced Parkinsonian syndrome (PS) revealed significant quantitative changes of 86 proteins under the influence of rotenone. This neurotoxin mainly caused the increase of the quantity of proteins involved in signal transduction and regulation of enzyme activity (24), proteins involved in cytoskeleton formation and exocytosis (23), and enzymes involved in energy generation and carbohydrate metabolism (19). However, only 11 of these proteins referred to isatin-binding proteins; the content of eight of them increased while the content of three proteins decreased. This suggests that the dramatic change of the profile of isatin-binding proteins, found in the development of the rotenone-induced PS, comes from changes in the state of the pre-existing molecules of proteins, rather than altered expression of corresponding genes.

[Characteristics of behavioral reactions and the profile of brain isatin-binding proteins of rats with the rotenone-induced experimental parkinsonism]

The neurotoxins rotenone and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (МPTP) are used for modeling Parkinson's disease in animals (PD). They induce the mitochondrial respiratory chain dysfunction, which leads to the dopaminergic (DA) neuron degeneration. The advantage of the rotenone model consists in ability of rotenone to cause neurodegeneration showing symptoms and molecular biological characteristics similar to those of PD. Isatin (indoldione-2,3) is an endogenous regulator found in tissues and biological fluids of humans and animals. It exhibits a broad range of biological activity mediated by numerous isatin-binding proteins. In this work we have investigated behavioral reactions and profiles of brain isatin-binding proteins of rats with Parkinson's syndrome (PS) in comparison with the corresponding parameters of MPTP-induced Parkinsonism in mice. Systemic injection of rotenone caused severe PS comparable with the effect of MPTP injection. It was accompanied by significant body weight loss, death, oligokinesia, muscular rigidity, and postural instability of animals. In spite of the same pathogenic basis of PS caused by rotenone and MPTP, the molecular mechanisms of their action differ. In the case of rotenone-induced PS, the pool of isatin-binding proteins common of the control rats and the rats with PS (146) significantly exceeded the pool of the common proteins of control mice and mice with PS induced by MPTP, whether right after neurotoxin injection (27), or (all the more) in a week after the MPTP injection (14). The comparison of isatin-binding proteins specific of the animals with MPTP-induced PS and with the rotenone-induced PS (as compared with the control animals) revealed total absence of proteins common of these two models of PD. It is to be noted that both neurotoxins particularly affected the proteins participating in the signal transmission and enzyme activity regulation. The changes of the profile of isatin-binding proteins in response to the injection of rotenone suggest that the neuroprotector isatin could also influence positively in the case of the rotenone model of PD.

Biological Evaluation of Valeriana Extracts from Argentina with Potent Cholinesterase Inhibition for the Treatment of Neurodegenerative Disorders and Their Comorbidities-The Case of Valeriana carnosa Sm. (Caprifoliaceae) Studied in Mice

Alzheimer's disease (AD) is a neurodegenerative disorder whose pathophysiology includes the abnormal accumulation of proteins (e.g., β-amyloid), oxidative stress, and alterations in neurotransmitter levels, mainly acetylcholine. Here we present a comparative study of the effect of extracts obtained from endemic Argentinian species of valerians, namely V. carnosa Sm., V. clarionifolia Phil. and V. macrorhiza Poepp. ex DC from Patagonia and V. ferax (Griseb.) Höck and V. effusa Griseb., on different AD-related biological targets. Of these anxiolytic, sedative and sleep-inducing valerians, V. carnosa proved the most promising and was assayed in vivo. All valerians inhibited acetylcholinesterase (IC₅₀ between 1.08-12.69 mg/mL) and butyrylcholinesterase (IC₅₀ between 0.0019-1.46 mg/mL). They also inhibited the aggregation of β-amyloid peptide, were able to chelate Fe²⁺ ions, and exhibited a direct relationship between antioxidant capacity and phenolic content. Moreover, V. carnosa was able to inhibit human monoamine oxidase A (IC₅₀: 0.286 mg/mL (0.213-0.384)). A daily intake of aqueous V. carnosa extract by male Swiss mice (50 and 150 mg/kg/day) resulted in anxiolytic and antidepressant-like behavior and improved spatial memory. In addition, decreased AChE activity and oxidative stress markers were observed in treated mouse brains. Our studies contribute to the development of indigenous herbal medicines as therapeutic agents for AD.

[The key role of the regulatory 19S subunit in changes in the brain proteasome subproteome induced by the neuroprotector isatin]

Isatin (indole-2,3-dione) is an endogenous regulator exhibiting various effects mediated by numerous isatin-binding proteins localized in different compartments of cells of the brain and peripheral tissues. It attenuates manifestations of experimental parkinsonism induced by administration of the MPTP neurotoxin and reduces the movement disorders characteristic of this disease. The molecular mechanisms of the neuroprotective action of isatin include its direct interaction with proteasomes, intracellular supramolecular complexes responsible for the targeted elimination of proteins. Incubation of fractions of 26S and 20S rabbit brain proteasomes, containing the whole spectrum of proteasomal subunits, as well as a number of proteasome-associated proteins, with isatin (100 μM) had a significant impact on the profile of released proteins. In the case of 26S proteasomes containing, in addition to the core part (20S proteasome), 19S regulatory subparticles, incubation with isatin resulted in a more than threefold increase in the number of dissociated proteins. In the case of 20S proteasomes (containing only the 20S core particle), incubation with isatin resulted in a significant decrease in the number of dissociated proteins compared to the control. Our results indicate an important role of the regulatory 19S subunit components in the formation of the proteasome subproteome and the sensitivity of these supramolecular complexes to isatin.

Prediction of CIAPIN1 (Cytokine-Induced Apoptosis Inhibitor 1) Signaling Pathway and Its Role in Cholangiocarcinoma Metastasis

Cholangiocarcinoma (CCA), a malignancy of the biliary epithelium, can arise at any point in the biliary system. We previously reported that CIAPIN1 is detectable in the sera and that its overexpression was associated with poor prognosis and metastasis of CCA patients. In this study, we investigated further its expression in CCA tissues, biological functions, and related signaling pathways in CCA cells. First, we examined CIAPIN1 expression in CCA tissues of 39 CCA patients using immunohistochemistry (IHC). Then, CIAPIN1-related proteins expressed in CCA cells were identified using RNA interference (siRNA) and liquid chromatography–mass spectrometry (LC–MS/MS). To predict the functions and signaling pathways of CIAPIN1 in CCA cells, the identified proteins were analyzed using bioinformatics tools. Then, to validate the biological functions of CIAPIN1 in the CCA cell line, transwell migration/invasion assays were used. CIAPIN1 was overexpressed in CCA tissues compared with adjacent noncancerous tissues. Its overexpression was correlated with lymph node metastasis. Bioinformatic analyses predicted that CIAPIN1 is connected to the TGF-β/SMADs signaling pathway via nitric oxide synthase 1 (NOS1) and is involved in the metastasis of CCA cells. In fact, cell migration and invasion activities of the KKU-100 CCA cell line were significantly suppressed by CIAPIN1 gene silencing. Our results unravel its novel function and potential signaling pathway in metastasis of CCA cells. CIAPIN1 can be a poor prognostic factor and can be a promising target molecule for CCA chemotherapy.

Tryptophan Metabolites as Mediators of Microbiota-Gut-Brain Communication: Focus on Isatin

Isatin (indole-2,3-dione) is an endogenous regulator, exhibiting various behavioral, biological, and pharmacological activities. Synthesis of isatin includes several crucial stages: cleavage of the tryptophan side chain and subsequent oxidation of the indole nucleus. Although these stages require concerted action of bacterial and host enzymes, there are two pathways of isatin formation: the host and bacterial pathways. Isatin acts as a neuroprotector in different experimental models of neurodegeneration. Its effects are realized via up- and downregulation of isatin-responsive genes and via interaction with numerous isatin-binding proteins identified in the brain. The effect of isatin on protein-protein interactions in the brain may be important for realization of weak inhibition of multiple receptor targets.

Atypical Ubiquitination and Parkinson's Disease

Ubiquitination (the covalent attachment of ubiquitin molecules to target proteins) is one of the main post-translational modifications of proteins. Historically, the type of polyubiquitination, which involves K48 lysine residues of the monomeric ubiquitin, was the first studied type of ubiquitination. It usually targets proteins for their subsequent proteasomal degradation. All the other types of ubiquitination, including monoubiquitination; multi-monoubiquitination; and polyubiquitination involving lysine residues K6, K11, K27, K29, K33, and K63 and N-terminal methionine, were defined as atypical ubiquitination (AU). Good evidence now exists that AUs, participating in the regulation of various cellular processes, are crucial for the development of Parkinson's disease (PD). These AUs target various proteins involved in PD pathogenesis. The K6-, K27-, K29-, and K33-linked polyubiquitination of alpha-synuclein, the main component of Lewy bodies, and DJ-1 (another PD-associated protein) is involved in the formation of insoluble aggregates. Multifunctional protein kinase LRRK2 essential for PD is subjected to K63- and K27-linked ubiquitination. Mitophagy mediated by the ubiquitin ligase parkin is accompanied by K63-linked autoubiquitination of parkin itself and monoubiquitination and polyubiquitination of mitochondrial proteins with the formation of both classical K48-linked ubiquitin chains and atypical K6-, K11-, K27-, and K63-linked polyubiquitin chains. The ubiquitin-specific proteases USP30, USP33, USP8, and USP15, removing predominantly K6-, K11-, and K63-linked ubiquitin conjugates, antagonize parkin-mediated mitophagy.

DJ-1 Protein and Its Role in the Development of Parkinson's Disease: Studies on Experimental Models

DJ-1, also known as Parkinson's disease protein 7, is a multifunctional protein ubiquitously expressed in cells and tissues. Interacting with proteins of various intracellular compartments, DJ-1 plays an important role in maintaining different cellular functions. Mutant DJ-1 forms containing amino acid substitutions (especially L166P), typical of Parkinson's disease, are characterized by impaired dimerization, stability, and folding. DJ-1 exhibits several types of catalytic activity; however, in the enzyme classification it exists as protein deglycase (EC 3.5.1.124). Apparently, in different cell compartments DJ-1 exhibits catalytic and non-catalytic functions, and their ratio still remains unknown. Oxidative stress promotes dissociation of cytoplasmic DJ-1 dimers into monomers, which are translocated to the nucleus, where this protein acts as a coactivator of various signaling pathways, preventing cell death. In mitochondria, DJ-1 is found in the synthasome, where it interacts with the β ATP synthase subunit. Downregulation of the DJ-1 gene under conditions of experimental PD increases sensitivity of the cells to neurotoxins, and introduction of the recombinant DJ-1 protein attenuates manifestation of this pathology. The thirteen-membered fragment of the DJ-1 amino acid sequence attached to the heptapeptide of the TAT protein penetrating into the cells exhibited neuroprotective properties in various PD models both in cell cultures and after administration to animals. Low molecular weight DJ-1 ligands also demonstrate therapeutic potential, providing neuroprotective effects seen during their incubation with cells and administration to animals.

Maternal Iron Deficiency Modulates Placental Transcriptome and Proteome in Mid-Gestation of Mouse Pregnancy

BACKGROUND

Maternal iron deficiency (ID) is associated with poor pregnancy and fetal outcomes. The effect is thought to be mediated by the placenta but there is no comprehensive assessment of placental responses to maternal ID. Additionally, whether the influence of maternal ID on the placenta differs by fetal sex is unknown.

OBJECTIVES

To identify gene and protein signatures of ID mouse placentas at mid-gestation. A secondary objective was to profile the expression of iron genes in mouse placentas across gestation.

METHODS

We used a real-time PCR-based array to determine the mRNA expression of all known iron genes in mouse placentas at embryonic day (E) 12.5, E14.5, E16.5, and E19.5 (n = 3 placentas/time point). To determine the effect of maternal ID, we performed RNA sequencing and proteomics in male and female placentas from ID and iron-adequate mice at E12.5 (n = 8 dams/diet).

RESULTS

In female placentas, 6 genes, including transferrin receptor (Tfrc) and solute carrier family 11 member 2, were significantly changed by maternal ID. An additional 154 genes were altered in male ID placentas. A proteomic analysis quantified 7662 proteins in the placenta. Proteins translated from iron-responsive element (IRE)-containing mRNA were altered in abundance; ferritin and ferroportin 1 decreased, while TFRC increased in ID placentas. Less than 4% of the significantly altered genes in ID placentas occurred both at the transcriptional and translational levels.

CONCLUSIONS

Our data demonstrate that the impact of maternal ID on placental gene expression in mice is limited in scope and magnitude at mid-gestation. We provide strong evidence for IRE-based transcriptional and translational coordination of iron gene expression in the mouse placenta. Finally, we discover sexually dimorphic effects of maternal ID on placental gene expression, with more genes and pathways altered in male compared with female mouse placentas.

Bacterial Metabolites of Human Gut Microbiota Correlating with Depression

Depression is a global threat to mental health that affects around 264 million people worldwide. Despite the considerable evolution in our understanding of the pathophysiology of depression, no reliable biomarkers that have contributed to objective diagnoses and clinical therapy currently exist. The discovery of the microbiota-gut-brain axis induced scientists to study the role of gut microbiota (GM) in the pathogenesis of depression. Over the last decade, many of studies were conducted in this field. The productions of metabolites and compounds with neuroactive and immunomodulatory properties among mechanisms such as the mediating effects of the GM on the brain, have been identified. This comprehensive review was focused on low molecular weight compounds implicated in depression as potential products of the GM. The other possible mechanisms of GM involvement in depression were presented, as well as changes in the composition of the microbiota of patients with depression. In conclusion, the therapeutic potential of functional foods and psychobiotics in relieving depression were considered. The described biomarkers associated with GM could potentially enhance the diagnostic criteria for depressive disorders in clinical practice and represent a potential future diagnostic tool based on metagenomic technologies for assessing the development of depressive disorders.

Mechanism of the Affinity-Enhancing Effect of Isatin on Human Ferrochelatase and Adrenodoxin Reductase Complex Formation: Implication for Protein Interactome Regulation

Isatin (indole-2, 3-dione) is a non-peptide endogenous bioregulator exhibiting a wide spectrum of biological activity, realized in the cell via interactions with numerous isatin-binding proteins, their complexes, and (sub) interactomes. There is increasing evidence that isatin may be involved in the regulation of complex formations by modulating the affinity of the interacting protein partners. Recently, using Surface Plasmon Resonance (SPR) analysis, we have found that isatin in a concentration dependent manner increased interaction between two human mitochondrial proteins, ferrochelatase (FECH), and adrenodoxine reductase (ADR). In this study, we have investigated the affinity-enhancing effect of isatin on the FECH/ADR interaction. The SPR analysis has shown that FECH forms not only homodimers, but also FECH/ADR heterodimers. The affinity-enhancing effect of isatin on the FECH/ADR interaction was highly specific and was not reproduced by structural analogues of isatin. Bioinformatic analysis performed using three dimensional (3D) models of the interacting proteins and in silico molecular docking revealed the most probable mechanism involving FECH/isatin/ADR ternary complex formation. In this complex, isatin is targeted to the interface of interacting FECH and ADR monomers, forming hydrogen bonds with both FECH and ADR. This is a new regulatory mechanism by which isatin can modulate protein-protein interactions (PPI).