Indirubin-3-Oxime Prevents H2O2-Induced Neuronal Apoptosis via Concurrently Inhibiting GSK3β and the ERK Pathway

Serinc2 deficiency exacerbates sepsis-induced cardiomyopathy by enhancing necroptosis and apoptosis

In critical care medicine, sepsis is a potentially fatal syndrome characterized by multi-organ dysfunction and eventual failure. Sepsis-induced cardiomyopathy (SIC) is characterized by decreased venstricular contractility. Serine incorporator 2 (Serinc2) is a protein involved in phosphatidylserine biosynthesis and membrane incorporation. It may also be a protective factor in septic lung injury. However, it is unknown whether Serinc2 influences SIC onset or progression. In the present study, we found that Serinc2 was downregulated in the cardiomyocytes of cecal ligation and puncture (CLP)-induced SIC and in neonatal rat cardiomyocytes (NRCMs) exposed to lipopolysaccharides (LPS). Serinc2 knockout (KO) exacerbated sepsis-induced myocardial inflammation, necroptosis, apoptosis, myocardial damage, and contractility impairment. Furthermore, the lack of Serinc2 in cardiomyocytes aggravated LPS-induced cardiomyopathic inflammation, necroptosis, and apoptosis. An adenovirus overexpressing Serinc2 inhibited the inflammatory response and favored cardiomyocyte survival. A mechanistic analysis revealed that Serinc2 deficiency exacerbated LPS-induced cardiac dysfunction by inhibiting the protein kinase B (Akt)/glycogen synthase kinase 3 beta (GSK-3β) signaling pathway that regulates necrotic complex formation and apoptotic pathways in cardiomyopathy. The findings of the present work demonstrated that Serinc2 plays an essential role in SIC and is, therefore, promising as a prophylactic and therapeutic target for this condition.

GSK-3β: An exuberating neuroinflammatory mediator in Parkinson's disease

Neuroinflammation is a critical degradative condition affecting neurons in the brain. Progressive neurodegenerative conditions such as Alzheimer's disease and Parkinson's disease (PD) have been strongly linked to neuroinflammation. The trigger point for inflammatory conditions in the cells and body is the physiological immune system. The immune response mediated by glial cells and astrocytes can rectify the physiological alterations occurring in the cell for the time being but prolonged activation leads to pathological progression. The proteins mediating such an inflammatory response, as per the available literature, are undoubtedly GSK-3β, NLRP3, TNF, PPARγ, and NF-κB, along with a few other mediatory proteins. NLRP3 inflammasome is undeniably a principal instigator of the neuroinflammatory response, but the regulatory pathways controlling its activation are still unclear, besides less clarity for the interplay between different inflammatory proteins. Recent reports have suggested the involvement of GSK-3β in regulating NLRP3 activation, but the exact mechanistic pathway remains vague. In the current review, we attempt to provide an elaborate description of crosstalk between inflammatory markers and GSK-3β mediated neuroinflammation progression, linking it to regulatory transcription factors and posttranslational modification of proteins. The recent clinical therapeutic advances targeting these proteins are also discussed in parallel to provide a comprehensive view of the progress made in PD management and lacunas still existing in the field.

Neuroprotective Effects of an Edible Pigment Brilliant Blue FCF against Behavioral Abnormity in MCAO Rats

Ischemic stroke leads to hypoxia-induced neuronal death and behavioral abnormity, and is a major cause of death in the modern society. However, the treatments of this disease are limited. Brilliant Blue FCF (BBF) is an edible pigment used in the food industry that with multiple aromatic rings and sulfonic acid groups in its structure. BBF and its derivatives were proved to cross the blood-brain barrier and have advantages on the therapy of neuropsychiatric diseases. In this study, BBF, but not its derivatives, significantly ameliorated chemical hypoxia-induced cell death in HT22 hippocampal neuronal cell line. Moreover, protective effects of BBF were attributed to the inhibition of the extracellular regulated protein kinase (ERK) and glycogen synthase kinase-3β (GSK3β) pathways as evidenced by Western blotting analysis and specific inhibitors. Furthermore, BBF significantly reduced neurological and behavioral abnormity, and decreased brain infarct volume and cerebral edema induced by middle cerebral artery occlusion/reperfusion (MCAO) in rats. MCAO-induced increase of p-ERK in ischemic penumbra was reduced by BBF in rats. These results suggested that BBF prevented chemical hypoxia-induced otoxicity and MCAO-induced behavioral abnormity via the inhibition of the ERK and GSK3β pathways, indicating the potential use of BBF for treating ischemic stroke

Pharmacological properties of indirubin and its derivatives

BACKGROUND

Indirubin is the main bioactive component of the traditional Chinese medicine Indigo naturalis and is a bisindole alkaloid. Multiple studies have shown that indirubin exhibits good anticancer, anti-inflammatory and neuroprotective properties.

METHODS

The purpose of this review is to provide a summary of the pharmacological mechanisms of indirubin and its derivatives.

RESULTS

Indirubin and its derivatives exert anticancer effects by regulating the expression of cyclin-dependent kinases (CDKs), GSK-3β, Bax, Bcl-2, C-MYC, matrix metalloproteinases (MMPs), and focal adhesion kinase (FAK) through the PI3K/AKT/mTOR, nuclear factor (NF)-κB, mitogen-activated protein kinase (MAPK), JAK/signal transducer and activator of transcription 3 (STAT3) pathways and other signaling pathways. We also reviewed the anti-inflammatory and neuroprotective properties of indirubin and its derivatives.

CONCLUSION

The findings of recent studies assessing indirubin and its derivatives suggest that these compounds can be used as potential drugs to treat tumors, inflammation, neuropathy and bacterial infection.

Silibinin Protects against H2O2-Induced Oxidative Damage in SH-SY5Y Cells by Improving Mitochondrial Function

Oxidative stress plays a critical role in the pathogenesis of various neurodegenerative diseases. Increasing evidence suggests the association of mitochondrial abnormalities with oxidative stress-related neural damage. Silibinin, a natural flavonol compound isolated from Silybum marianum, exhibits multiple biological activities. The present study investigated the effects of silibinin on H₂O₂-induced oxidative stress in human neuroblastoma SH-SY5Y cells. Exposure to H₂O₂ (750 µM) reduced the viability of SH-SY5Y cells, which was coupled with increased reactive oxygen species (ROS), abnormal cell morphology, and mitochondrial dysfunction. Remarkably, silibinin (1, 5, and 10 µM) treatment attenuated the H₂O₂-induced cell death. Moreover, silibinin reduced ROS production and the levels of malondialdehyde (MDA), increased the levels of superoxide dismutase (SOD) and glutathione (GSH), and increased mitochondrial membrane potential. Moreover, silibinin normalized the expression of nuclear factor 2-related factor 2 (Nrf2)-related and mitochondria-associated proteins. Taken together, our findings demonstrated that silibinin could attenuate H₂O₂-induced oxidative stress by regulating Nrf2 signaling and improving mitochondrial function in SH-SY5Y cells. The protective effect against oxidative stress suggests silibinin as a potential candidate for preventing neurodegeneration.

Altered expression of miR-29a-3p and miR-34a-5p by specific inhibition of GSK3β in the MPP+ treated SH-SY5Y Parkinson's model

In the current study, the effects of 7-BIO as a specific GSK3β inhibitor was examined on cell survival and expression of miR-29a-3p and miR-34a-5p in neurotoxin MPP⁺ treated SH-SY5Y cells. Our findings revealed that while co-treatment of the cells with 7-BIO and MPP⁺ did not alter the toxicity induced by MPP⁺, pretreatment with 3.5 μM 7-BIO for 6 h increased the survival of the 2 mM MPP⁺ treated cells. Also, qRT-PCR analysis of gene expression showed that while miR-29a-3p was unchanged in cells treated with either 2 mM MPP⁺ or 3.5 μM 7-BIO alone, miR-34a-5p was increased by MPP⁺ but decreased by 7-BIO. Pretreatment with 3.5 μM 7-BIO prior to MPP⁺ however, increased miR-29a-3p but decreased miR-34a-5p induced by MPP⁺. We therefore suggest that 7-BIO inhibition of GSK3β alleviates the MPP⁺ induced neurotoxicity by regulating miR-29a-3p and miR-34a-5p expressions in Parkinson's disease model SH-SY5Y cells.

Oximes: Novel Therapeutics with Anticancer and Anti-Inflammatory Potential

Oximes have been studied for decades because of their significant roles as acetylcholinesterase reactivators. Over the last twenty years, a large number of oximes have been reported with useful pharmaceutical properties, including compounds with antibacterial, anticancer, anti-arthritis, and anti-stroke activities. Many oximes are kinase inhibitors and have been shown to inhibit over 40 different kinases, including AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (PI3K), cyclin-dependent kinase (CDK), serine/threonine kinases glycogen synthase kinase 3 α/β (GSK-3α/β), Aurora A, B-Raf, Chk1, death-associated protein-kinase-related 2 (DRAK2), phosphorylase kinase (PhK), serum and glucocorticoid-regulated kinase (SGK), Janus tyrosine kinase (JAK), and multiple receptor and non-receptor tyrosine kinases. Some oximes are inhibitors of lipoxygenase 5, human neutrophil elastase, and proteinase 3. The oxime group contains two H-bond acceptors (nitrogen and oxygen atoms) and one H-bond donor (OH group), versus only one H-bond acceptor present in carbonyl groups. This feature, together with the high polarity of oxime groups, may lead to a significantly different mode of interaction with receptor binding sites compared to corresponding carbonyl compounds, despite small changes in the total size and shape of the compound. In addition, oximes can generate nitric oxide. This review is focused on oximes as kinase inhibitors with anticancer and anti-inflammatory activities. Oximes with non-kinase targets or mechanisms of anti-inflammatory activity are also discussed.

Functions of Small Organic Compounds that Mimic the HNK-1 Glycan

Because of the importance of the HNK-1 carbohydrate for preferential motor reinnervation after injury of the femoral nerve in mammals, we screened NIH Clinical Collection 1 and 2 Libraries and a Natural Product library comprising small organic compounds for identification of pharmacologically useful reagents. The reason for this attempt was to obviate the difficult chemical synthesis of the HNK-1 carbohydrate and its isolation from natural sources, with the hope to render such compounds clinically useful. We identified six compounds that enhanced neurite outgrowth from cultured spinal motor neurons at nM concentrations and increased their neurite diameter, but not their neurite branch points. Axons of dorsal root ganglion neurons did not respond to these compounds, a feature that is in agreement with their biological role after injury. We refer to the positive functions of some of these compounds in animal models of injury and delineate the intracellular signaling responses elicited by application of compounds to cultured murine central nervous system neurons. Altogether, these results point to the potential of the HNK-1 carbohydrate mimetics in clinically-oriented settings.

Isolation of Antibacterial, Nitrosylmyoglobin Forming Lactic Acid Bacteria and Their Potential Use in Meat Processing

The use of nitrite as a colorant and preservative in meat processing is associated with health risks. This study aimed to isolate nitrite-substituting lactic acid bacteria for use as natural biological colorants and preservatives. Among the 106 strains isolated from fermented foods, two strains with excellent ability to convert myoglobin and metmyoglobin (Met-Mb) to red nitrosylmyoglobin (Mb-NO) were selected. The superior ability to form Mb-NO was confirmed through UV-visible spectrophotometry, Fourier transform infrared spectrometry, electron spin resonance analysis, nitric oxide synthase activity assay, and Met-Mb reductase activity assay. The potent antibacterial activity was confirmed through biofilm and cytomembrane breakage of the indicator bacteria. Though performing 16S rDNA sequencing, they were identified as two different strains of Lactobacillus plantarum. Based on their favorable characteristics, their applications in the meat industry were further evaluated. This study identified a novel dual-function natural biological colorant and preservative to substitute nitrite in meat products. The application of the two strains would decrease the hazardous of nitrite to health.

Inhibition of Transcription Induces Phosphorylation of YB-1 at Ser102 and Its Accumulation in the Nucleus

The Y-box binding protein 1 (YB-1) is an RNA/DNA-binding protein regulating gene expression in the cytoplasm and the nucleus. Although mostly cytoplasmic, YB-1 accumulates in the nucleus under stress conditions. Its nuclear localization is associated with aggressiveness and multidrug resistance of cancer cells, which makes the understanding of the regulatory mechanisms of YB-1 subcellular distribution essential. Here, we report that inhibition of RNA polymerase II (RNAPII) activity results in the nuclear accumulation of YB-1 accompanied by its phosphorylation at Ser102. The inhibition of kinase activity reduces YB-1 phosphorylation and its accumulation in the nucleus. The presence of RNA in the nucleus is shown to be required for the nuclear retention of YB-1. Thus, the subcellular localization of YB-1 depends on its post-translational modifications (PTMs) and intracellular RNA distribution.

Ginsenoside Rg3 protects mouse leydig cells against triptolide by downregulation of miR-26a

BACKGROUND

Ginsenoside Rg3 has been reported to exert protection function on germ cells. However, the mechanisms by which Rg3 regulates apoptosis in mouse Leydig cells remain unclear. In addition, triptolide (TP) has been reported to induce infertility in male rats. Thus, this study aimed to investigate the protective effect of Rg3 against TP-induced toxicity in MLTC-1 cells.

METHODS

CCK-8, immunofluorescence assay, Western blotting and flow cytometry were used to detect cell proliferation and cell apoptosis, respectively. In addition, the dual luciferase reporter system assay was used to detect the interaction between miR-26a and GSK3β in MLTC-1 cells.

RESULTS

TP significantly inhibited the proliferation of MLTC-1 cells, while the inhibitory effect of TP was reversed by Rg3. In addition, TP markedly induced apoptosis in MLTC-1 cells via increasing the expressions of Bax, active caspase 3, Cyto c and active caspase 9, and decreasing the level of Bcl-2. However, Rg3 alleviated TP-induced apoptosis of MLTC-1 cells. Moreover, the level of miR-26a was obviously downregulated by Rg3 treatment. The protective effect of Rg3 against TP-induced toxicity in MLTC-1 cells was abolished by miR-26a upregulation. Meanwhile, dual-luciferase assay showed GSK3β was the direct target of miR-26a in MLTC-1 cells. Overexpression of miR-26a markedly decreased the level of GSK3β. As expected, upregulation of miR-26a could abrogate the protective effects of Rg3 against TP-induced cytotoxicity via inhibiting the expression of GSK3β.

CONCLUSION

These results indicated that Rg3 could protect MLTC-1 against TP by downregulation of miR-26a. Therefore, Rg3 might serve as a potential agent for the treatment of male hypogonadism.

Orexin-A protects SH-SY5Y cells against H2O2-induced oxidative damage via the PI3K/MEK1/2/ERK1/2 signaling pathway

Orexin-A elicits multiple potent effects on a variety of tumor cells via different signaling pathways. However, it is unknown whether it has a neuroprotective effect on SH-SY5Y human neuroblastoma cells. This study investigated the neuroprotective effect of Orexin-A against hydrogen peroxide (H₂O₂)-induced oxidative damage in SH-SY5Y cells and the underlying mechanism. H₂O₂ treatment decreased the viability of SH-SY5Y cells, induced apoptosis, and decreased superoxide dismutase activity. Orexin-A attenuated these effects, indicating that it protects SH-SY5Y cells against H₂O₂-induced oxidative damage. Pre-treatment with Orexin-A also attenuated H₂O₂-induced increases in phosphorylation of MEK_1/2 and ERK_1/2. Moreover, these effects of Orexin-A were reduced in the presence of the PI3K inhibitor LY294002. Finally, pre-treatment with LY294002 abrogated attenuation of the H₂O₂-induced decrease in cell viability and increase in caspase-3/7 activity by Orexin-A. These results show that the PI3K/MEK_1/2/ERK_1/2 signaling pathway is involved in the neuroprotective effects of Orexin-A against H₂O₂-induced oxidative damage in SH-SY5Y cells. Our findings provide insight into the neuroprotective effects of Orexin-A and the underlying mechanism, which will be useful for the treatment of nervous system diseases.

Eckmaxol, a Phlorotannin Extracted from Ecklonia maxima, Produces Anti-β-amyloid Oligomer Neuroprotective Effects Possibly via Directly Acting on Glycogen Synthase Kinase 3β

Alzheimer's disease is a progressive neurodegenerative disorder that mainly affects the elderly. Soluble β-amyloid oligomer, which can induce neurotoxicity, is generally regarded as the main neurotoxin in Alzheimer's disease. Here we report that eckmaxol, a phlorotannin extracted from the brown alga Ecklonia maxima, could produce neuroprotective effects in SH-SY5Y cells. Eckmaxol effectively prevented but did not rescue β-amyloid oligomer-induced neuronal apoptosis and increase of intracellular reactive oxygen species. Eckmaxol also significantly reversed the decreased expression of phospho-Ser9-glycogen synthase kinase 3β and increased expression of phospho-extracellular signal-regulated kinase, which was induced by Aβ oligomer. Moreover, both glycogen synthase kinase 3β and mitogen activated protein kinase inhibitors produced neuroprotective effects in SH-SY5Y cells. Furthermore, eckmaxol showed favorable interaction in the ATP binding site of glycogen synthase kinase 3β and mitogen activated protein kinase. These results suggested that eckmaxol might produce neuroprotective effects via concurrent inhibition of glycogen synthase kinase 3β and extracellular signal-regulated kinase pathways, possibly via directly acting on glycogen synthase kinase 3β and mitogen activated protein kinase. Based on the central role that β-amyloid oligomers play in the pathogenesis of Alzheimer's disease and the high annual production of Ecklonia maxima for alginate and other nutritional ingredients, this report represents a new candidate for the treatment of Alzheimer's disease, and also expands the potential application of Ecklonia maxima and its constituents in the field of pharmacology.

Effects of indirubin and isatin on cell viability, mutagenicity, genotoxicity and BAX/ERCC1 gene expression

CONTEXT

Indigofera suffruticosa Miller (Fabaceae) and I. truxillensis Kunth produce compounds, such as isatin (ISA) and indirubin (IRN), which possess antitumour properties. Their effects in mammalian cells are still not very well understood.

OBJECTIVE

We evaluated the activities of ISA and/or IRN on cell viability and apoptosis in vitro, their genotoxic potentials in vitro and in vivo, and the IRN- and ISA-induced expression of ERCC1 or BAX genes.

MATERIALS AND METHODS

HeLa and/or CHO-K1 cell lines were tested (3 or 24 h) in the MTT, Trypan blue exclusion, acridine orange/ethidium bromide, cytokinesis-blocked micronucleus (CBMN) and comet (36, 24 and 72 h) tests after treatment with IRN (0.1 to 200 μM) or ISA (0.5 to 50 μM). Gene expression was measured by RT-qPCR in HeLa cells. Swiss albino mice received IRN (3, 4 or 24 h) by gavage (50, 100 and 150 mg/kg determined from the LD₅₀ - 1 g/kg b.w.) and submitted to comet assay in vivo.

RESULTS

IRN reduced the viability of CHO-K1 (24 h; 5 to 200 μM) and HeLa cells (10 to 200 μM), and was antiproliferative in the CBMN test (CHO-K1: 0.5 to 10 μM; HeLa: 5 and 10 μM). The drug did not induce apoptosis, micronucleus neither altered gene expression. IRN and ISA were genotoxic for HeLa cells (3 and 24 h) at all doses tested. IRN (100 and 150 mg/kg) also induced genotoxicity in vivo (4 h).

CONCLUSION

IRN and ISA have properties that make them candidates as chemotherapeutics for further pharmacological investigations.

Indirubin Derivative 7-Bromoindirubin-3-Oxime (7Bio) Attenuates Aβ Oligomer-Induced Cognitive Impairments in Mice

Indirubins are natural occurring alkaloids extracted from indigo dye-containing plants. Indirubins could inhibit various kinases, and might be used to treat chronic myelocytic leukemia, cancer and neurodegenerative disorders. 7-bromoindirubin-3-oxime (7Bio), an indirubin derivative derived from indirubin-3-oxime, possesses inhibitory effects against cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3β (GSK3β), two pharmacological targets of Alzheimer's disease (AD). In this study, we have discovered that 2.3–23.3 μg/kg 7Bio effectively prevented β-amyloid (Aβ) oligomer-induced impairments of spatial cognition and recognition without affecting bodyweight and motor functions in mice. Moreover, 7Bio potently inhibited Aβ oligomer-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Furthermore, 7Bio significantly prevented the decreased expression of synapsin-1 and PSD-95, biomarkers of pre-synaptic and post-synaptic proteins in Aβ oligomer-treated mice. The mean optical density (OD) with hyper-phosphorylated tau (pTau), glial fibrillary acidic protein (GFAP) and CD45 positive staining in the hippocampus of 7Bio-treated mice were significantly decreased compared to those of Aβ oligomer-treated mice. In addition, Western blotting analysis showed that 7Bio attenuated Aβ oligomer-decreased expression of pSer9-GSK3β. Those results suggested that 7Bio could potently inhibit Aβ oligomer-induced neuroinflammation, synaptic impairments, tau hyper-phosphorylation, and activation of astrocytes and microglia, which may contribute to the neuroprotective effects of 7Bio. Based on these findings, we expected that 7Bio might be developed as a novel anti-AD lead compound.

Fucoxanthin, a Marine Carotenoid, Attenuates β-Amyloid Oligomer-Induced Neurotoxicity Possibly via Regulating the PI3K/Akt and the ERK Pathways in SH-SY5Y Cells

Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by neurofibrillary tangles, synaptic impairments, and loss of neurons. Oligomers of β-amyloid (Aβ) are widely accepted as the main neurotoxins to induce oxidative stress and neuronal loss in AD. In this study, we discovered that fucoxanthin, a marine carotenoid with antioxidative stress properties, concentration dependently prevented Aβ oligomer-induced increase of neuronal apoptosis and intracellular reactive oxygen species in SH-SY5Y cells. Aβ oligomers inhibited the prosurvival phosphoinositide 3-kinase (PI3K)/Akt cascade and activated the proapoptotic extracellular signal-regulated kinase (ERK) pathway. Moreover, inhibitors of glycogen synthase kinase 3β (GSK3β) and mitogen-activated protein kinase (MEK) synergistically prevented Aβ oligomer-induced neuronal death, suggesting that the PI3K/Akt and ERK pathways might be involved in Aβ oligomer-induced neurotoxicity. Pretreatment with fucoxanthin significantly prevented Aβ oligomer-induced alteration of the PI3K/Akt and ERK pathways. Furthermore, LY294002 and wortmannin, two PI3K inhibitors, abolished the neuroprotective effects of fucoxanthin against Aβ oligomer-induced neurotoxicity. These results suggested that fucoxanthin might prevent Aβ oligomer-induced neuronal loss and oxidative stress via the activation of the PI3K/Akt cascade as well as inhibition of the ERK pathway, indicating that further studies of fucoxanthin and related compounds might lead to a useful treatment of AD.

Assessment of Neuronal Viability Using Fluorescein Diacetate-Propidium Iodide Double Staining in Cerebellar Granule Neuron Culture

Primary cultured Cerebellar Granule Neurons (CGNs) have been widely used as an in vitro model in neuroscience and neuropharmacology research. However, the co-existence of glial cells and neurons in CGN culture might lead to biases in the accurate assessment of neuronal viability. Fluorescein diacetate (FDA) and Propidium Iodide (PI) double staining has been used to measure cell viability by simultaneously evaluating the viable and dead cells. We used FDA-PI double staining to improve the sensitivities of the colorimetric assays and to evaluate neuronal viability in CGNs. Furthermore, we added blue fluorescent DNA stains (e.g., Hoechst) to improve the accuracy. This protocol describes how to improve the accuracy of assessment of neuronal viability by using these methods in CGN culture. Using this protocol, the number of glial cells can be excluded by using fluorescence microscopy. A similar strategy can be applied to distinguish the unwanted glial cells from neurons in various mixed cell cultures, such as primary cortical culture and hippocampal culture.