Involvement of lncRNA TUG1 in HIV-1 Tat-Induced Astrocyte Senescence.

HIV-1 infection in the era of combined antiretroviral therapy has been associated with premature aging. Among the various features of HIV-1 associated neurocognitive disorders, astrocyte senescence has been surmised as a potential cause contributing to HIV-1-induced brain aging and neurocognitive impairments. Recently, lncRNAs have also been implicated to play essential roles in the onset of cellular senescence. Herein, using human primary astrocytes (HPAs), we investigated the role of lncRNA TUG1 in HIV-1 Tat-mediated onset of astrocyte senescence. We found that HPAs exposed to HIV-1 Tat resulted in significant upregulation of lncRNA TUG1 expression that was accompanied by elevated expression of p16 and p21, respectively. Additionally, HIV-1 Tat-exposed HPAs demonstrated increased expression of senescence-associated (SA) markers-SA-ß-galactosidase (SA-ß-gal) activity and SA-heterochromatin foci-cell-cycle arrest, and increased production of reactive oxygen species and proinflammatory cytokines. Intriguingly, gene silencing of lncRNA TUG1 in HPAs also reversed HIV-1 Tat-induced upregulation of p21, p16, SA-ß gal activity, cellular activation, and proinflammatory cytokines. Furthermore, increased expression of astrocytic p16 and p21, lncRNA TUG1, and proinflammatory cytokines were observed in the prefrontal cortices of HIV-1 transgenic rats, thereby suggesting the occurrence of senescence activation in vivo. Overall, our data indicate that HIV-1 Tat-induced astrocyte senescence involves the lncRNA TUG1 and could serve as a potential therapeutic target for dampening accelerated aging associated with HIV-1/HIV-1 proteins.

Particulate Matters Affecting lncRNA Dysregulation and Glioblastoma Invasiveness: In Silico Applications and Current Insights.

With a reported rise in global air pollution, more than 50% of the population remains exposed to toxic air pollutants in the form of particulate matters (PMs). PMs, from various sources and of varying sizes, have a significant impact on health as long-time exposure to them has seen a correlation with various health hazards and have also been determined to be carcinogenic. In addition to disrupting known cellular pathways, PMs have also been associated with lncRNA dysregulation-a factor that increases predisposition towards the onset or progression of cancer. lncRNA dysregulation is further seen to mediate glioblastoma multiforme (GBM) progression. The vast array of information regarding cancer types including GBM and its various precursors can easily be obtained via innovative in silico approaches in the form of databases such as GEO and TCGA; however, a need to obtain selective and specific information correlating anthropogenic factors and disease progression-in the case of GBM-can serve as a critical tool to filter down and target specific PMs and lncRNAs responsible for regulating key cancer hallmarks in glioblastoma. The current review article proposes an in silico approach in the form of a database that reviews current updates on correlation of PMs with lncRNA dysregulation leading to GBM progression.

Docosahexaenoic acid increased MeCP2 mediated mitochondrial respiratory complexes II and III enzyme activities in cortical astrocytes.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the methyl-CpG-binding protein 2 (MeCP2) in the neurons and glial cells of the central nervous system. Currently, therapeutics for RTT is aimed at restoring the loss-of-function by MeCP2 gene therapy, but that approach has multiple challenges. We have already reported impaired mitochondrial bioenergetics in MeCP2 deficient astrocytes. Docosahexaenoic acid (DHA), a polyunsaturated fatty acid, has been shown with health benefits, but its impact on mitochondrial functions in MeCP2 deficient astrocytes has never been paid much attention. The present study aimed to investigate the effects of DHA on mitochondrial respiratory chain regulation in MeCP2 knockdown astrocytes. We determined NADH dehydrogenase (ubiquinone) flavoprotein 2 (Ndufv2-complex-I), Ubiquinol cytochrome c reductase core protein (Uqcrc1-complex-III) genes expression, Ndufv2 protein expression, respiratory electron transport chain complex I, II, III, and IV enzyme activities, intracellular Ca+2 , reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) in DHA pre-incubated MeCP2 knock-down rat primary cortical astrocytes. Our study demonstrates that 100 µM DHA increases MeCP2 gene and protein expression. Increases brain-derived neurotrophic factor (BDNF) and Uqcrc1 gene expression, Ndufv2 protein expression, but has no effect on glial fibrillary acidic protein (GFAP) gene expression. DHA treatment also increases mitochondrial respiratory Complexes II and III activities and reduces intracellular calcium levels. Taken together, the effects of DHA seem independent of MeCP2 deficiency in astrocytes. Hence, further studies are warranted to understand the complicated mechanisms of DHA and for its therapeutic significance in MeCP2-mediated mitochondrial dysfunction and in RTT disease.

Current insights on extracellular vesicle-mediated glioblastoma progression: Implications in drug resistance and epithelial-mesenchymal transition.

BACKGROUND: Glioblastoma multiforme (GBM) is one of the most fatal tumors of the central nervous system with high rate of disease progression, diagnosis, prognosis and low survival rate. Therapeutic approaches that relied on surgical resection and chemotherapy have been unable to curb the disease progression and subsequently leading to increase in incidences of GBM reoccurrence. SCOPE OF THE REVIEW: In the recent times, membrane-bound extracellular vesicles (EVs) have been observed as one of the key reasons for the uncontrolled growth of GBM. EVs are shown to have the potential to contribute to the disease progression via mediating drug resistance and epithelial-mesenchymal transition. The GBM-derived EVs (GDEVs) with its cargo contents act as the biological trojan horse and lead to disease progression after being received by the recipient target cells. This review article highlights the biophysical, biochemical properties of EVs, its cargo contents and its potential role in the growth and progression of GBM by altering tumour microenvironment. MAJOR CONCLUSIONS: EVs are being explored for serving as novel disease biomarkers in a variety of cancer types such as adenocarcinoma, pancreatic cancer, color rectal cancer, gliomas and glioblastomas. Improvement in the EV isolation protocols, polymer-based separation techniques and transcriptomics, have made EVs a key diagnostic marker to unravel the progression and early GBM diagnosis. GDEVs role in tumour progression is under extensive investigations. GENERAL SIGNIFICANCE: Attempts have been also made to discuss and compare the usage of EVs as potential therapeutic targets versus existing therapies targeting drug resistance and EMT.

Role of PDGF-A-Activated ERK Signaling Mediated FAK-Paxillin Interaction in Oligodendrocyte Progenitor Cell Migration.

Oligodendrocyte progenitor cells (OPCs) originate from the sub-ventricular zone of the developing brain. They migrate and proliferate to occupy the white matter tracts of the central nervous system and transform into myelinating oligodendrocytes. Along their route of migration, OPCs are guided and controlled by several growth factors and chemokines. PDGF-A (platelet-derived growth factor), a growth factor, serves as a monogenic and mitogenic cue during the process and activates intracellular signaling pathways inside the cell. Activation of extracellular signal regulated kinase (ERK) signaling is one of the mechanisms by which PDGF-A induces the migration of OPCs. However, the mechanisms governing the PDGF-A-induced ERK-driven OPCs migration are still unclear. In the current study, we investigated further the role of PDGF-A-induced ERK signaling in OPC migration. First, we confirmed the role of PDGF-A-activated ERK signaling in OPC migration using the pharmacological inhibitor U0126, or siRNA-mediated suppression of ERK expression. Then, we demonstrated that PDGF-A-induced actin reorganization and interaction of focal adhesion kinase (FAK), Paxillin, and pERK signals are impaired in OPCs treated with the MEK inhibitor U0126. Thus, our findings demonstrated that PDGF-A induces OPC migration in an ERK-dependent mechanism via regulation of actin reorganization and FAK-Paxillin interaction.

Neuroprotective effect of quercetin against radiation-induced endoplasmic reticulum stress in neurons.

The endoplasmic reticulum (ER) plays an important role in the regulation and maintenance of cellular homeostasis. However, unresolved ER stress leads to deleterious effects by inducing the accumulation of unfolded proteins in the cell. Here we have demonstrated the protective aspects of quercetin against radiation-induced ER stress and against inflammation in primary cultured dorsal root ganglion (DRG) neurons. The mature DRG neurons were pretreated with different concentrations of quercetin (5-100 µM) for 24 hours before 2 Gy gamma radiation exposure and then subjected to a cytotoxicity assay, quantitative real-time polymerase chain reaction and Western blot analysis. The results showed that quercetin decreased the expression of BiP and C/EBP-homologous protein, the ER stress marker genes along with downregulation of tumor necrosis factor-α, JNK in irradiated DRG neurons. Furthermore, quercetin pretreatment significantly increased the cytoskeletal protein Tuj1 and the neurotrophin brain-derived neurotrophic factor in the neuron. These results indicate that quercetin plays a neuroprotective role against radiation-mediated ER stress and inflammatory responses.

Role of astrocytic MeCP2 in regulation of CNS myelination by affecting oligodendrocyte and neuronal physiology and axo-glial interactions.

Astrocytes perform several critical functions such as promoting neuronal maturation, neuronal survival, maintaining and supporting neurons and oligodendrocytes. Astrocytes participate in the formation of nodes of Ranvier. Recently, studies emphasizing on the role of astrocytes in regulating myelination by secreting pro-myelinating factors like growth factors, neurotrophins and ECM proteins, have been investigated by many researchers. Methyl-CpG-Binding Protein 2 (MeCP2), an epigenetic protein, binds to CpG islands in the genome and induces multiple gene regulatory functions by conforming changes in the chromatin structure and resulting in cell-specific gene expression. MeCP2 deficient astrocytes have been linked with abnormal neuronal function including decreased dendritic arborization and decreased dendritic outgrowth. However, role of astrocytic MeCP2 in central nervous system myelination is largely not known. The data from the current study indicate altered mRNA levels (Lif, Cntf, Pdgfa, Cxcl10) of astrocyte-secreted factors involved in myelination. Bdnf and Ngf mRNA levels were also altered in MeCP2 knockdown astrocytes. Moreover, the secreted BDNF levels were significantly altered whereas there were no significant changes in NGF secretion. We also observed that astrocytic MeCP2 affects the morphology, physiology and survival of oligodendrocytes and neurons-two of the key players in myelination. Further, we report that some of the axo-glial interaction genes, namely Caspr, Notch1, Nf155 and Nrg1 are under the regulation of astrocytic MeCP2 along with key myelin genes and proteins.

MeCP2 Differentially Regulate the Myelin MBP and PLP Protein Expression in Oligodendrocytes and C6 Glioma.

MeCP2 (methyl-CpG binding protein 2), an epigenetic regulator, has been shown to regulate the function of neurons and glial cells. Our previous study has demonstrated that MeCP2 repress the myelin gene expression in rat oligodendrocytes but whether MeCP2 bind to myelin gene MBP and PLP is not yet known. Besides oligodendrocytes, C6 glioma also expresses myelin genes and could be used as a model system to study myelin gene expression. In the present study, we determined that MeCP2 directly bind to MBP, PLP, and BDNF promoter in oligodendrocytes. Further, it was found that MeCP2 differentially regulates the myelin gene expression in oligodendrocytes and C6 glioma. In contrast to oligodendrocytes, MeCP2 does not bind to promoter region of MBP and PLP in C6 glioma suggest that MeCP2 differentially regulates the gene expression in different cell types.

MeCP2 in central nervous system glial cells: current updates.

avMethyl­CpG binding protein 2 (MeCP2) is an epigenetic regulator, which preferentially binds to methylated CpG dinucleotides in DNA. MeCP2 mutations have been linked to Rett syndrome, a neurodevelopmental disorder characterized by severe intellectual disability in females. Earlier studies indicated that loss of MeCP2 function in neuronal cells was the sole cause of Rett syndrome. Subsequent studies have linked MeCP2 expression in CNS glial cells to Rett syndrome pathogenesis. In this review, we have discussed the role of MeCP2 in glial subtypes, astrocytes, oligodendrocytes and microglia, and how loss of MeCP2 function in these cells has a profound influence on both glial and neuronal function.

MeCP2 overexpression inhibits proliferation, migration and invasion of C6 glioma by modulating ERK signaling and gene expression.

MethylCpG binding protein-2 (MeCP2) is an epigenetic regulator and essential for brain development. MeCP2 mutations are associated with a spectrum of neuro-developmental disorders that vary depending on the patient gender, most notably Rett Syndrome. MeCP2 is essential for normal neuronal maturation, and glial cell function in the brain. Besides, its role in neurodevelopmental disorders, MeCP2 is involved in many cancers such as breast, colorectal, lung, liver, and prostate cancer. Glioma is the most lethal form of brain cancer. Studies have shown that dysfunctional epigenetic regulation plays a crucial role in glioma progression. Further, previous studies have suggested a role for MeCP2 in glioma pathogenesis. In this study, we show that MeCP2 may play a critical role in the suppression of glioma progression. Stable overexpression of MeCP2in C6 glioma cells inhibits proliferation, migration, invasion, and adhesion. Moreover, MeCP2 overexpression inhibits pERKand BDNF expression while inducing GFAP expression in C6 glioma. These findings suggest that MeCP2 may play a crucial role in suppression of glioma progression.

ER stress and genomic instability induced by gamma radiation in mice primary cultured glial cells.

Ionizing radiation induces various pathophysiological conditions by altering central nervous system (CNS) homeostasis, leading to neurodegenerative diseases. However, the potential effect of ionizing radiation response on cellular physiology in glial cells is unclear. In the present study, micronucleus test, comet assay, and RT-PCR were performed to investigate the potential effect of gamma radiation in cultured oligodendrocytes and astrocytes with respect to genomic instability, Endoplasmic Reticulum (ER) stress, and inflammation. Further, we studied the effect of alteration in ER stress specific gene expression in cortex post whole body radiation in mice. Results showed that exposure of gamma radiation of 2Gy in-vitro cultured astrocytes and oligodendrocytes and 7Gy in-vivo induced ER stress and Inflammation along with profuse DNA damage and Chromosomal abnormality. Additionally, we observed downregulation of myelin basic protein levels in cultured oligodendrocytes exposed to radiation. The present data suggests that ER stress and pro inflammatory cytokines serve as the major players in inducing glial cell dysfunction post gamma irradiation along with induction of genomic instability. Taken together, these results indicate that ER stress, DNA damage, and inflammatory pathways may be critical events leading to glial cell dysfunction and subsequent cell death following exposure to ionizing radiation.

PDGFR inhibition mediated intracellular signalling in C6 glioma growth and migration: role of ERK and ROCK pathway.

Aberrant PDGFR (Platelet derived growth factor receptor) signalling in brain tumors and gliomas is one of the primary cause of tumor progression. PDGFR stimulation by its ligand and the role of its downstream mediators such as extracellular regulated kinases (ERK1/2), PI3K and ROCK pathways have not been thoroughly investigated. The present study sought to investigate the role of PDGF receptor signalling inhibition on suppression of rat C6 glioma growth and migration. Treatment of C6 cells with PDGFR inhibitor, AG1295 caused a significant reduction in migration and proliferation by regulating the ERK and ROCK signalling. Subsequently, PDGFR blocking was demonstrated to regulate cytoskeleton reorganization by modulating the Actin-pMLC reorganization and pERK-FAK-Paxillin complex formation which may further regulate the C6 glioma migration. Further, other malignant behaviour of C6 glioma such as anchorage independent growth, adhesion, invasion and sphere forming abilities were found to be impaired by PDGFR blocking. PDGFR inhibition further regulates the C6 glioma tumor behaviour by inducing gene expression of GFAP, BDNF, and MECP2 and down regulating FAK expression. In conclusion, our data elucidate novel mechanisms involve in PDGFR inhibition mediated inhibition of C6 glioma growth and migration which can be a future potential target for the treatment of glioma.

Differential Regulation of MeCP2 Phosphorylation by Laminin in Oligodendrocytes.

Oligodendrocytes (OLGs) are the myelinating cells of the central nervous system (CNS), and its proper differentiation is crucial for normal functioning of neurons. Methyl-CpG-binding protein 2 (MeCP2) is a multifunctional methylated DNA binding protein; mutation of which causes Rett syndrome, a severe neurodevelopmental disorder. Previously, we reported that MeCP2 is expressed in all the stages of oligodendrocyte development, and also shown the role of MeCP2 as a transcription regulator of myelin genes in OLGs. The expression and function of MeCP2 phosphorylation at S80 (pS80MeCP2) has been well studied in neurons and astrocytes; however, there is no data so far available in OLGs regarding pS80MeCP2. Certain developmental stimuli such as growth factors and extracellular matrix (ECM) protein play important role in OLG development. In the present study, we have examined the effects of external stimuli (growth factors (GFs) and extracellular matrix (ECMs)) on S80 phosphorylation of MeCP2 in N19 oligodendroglial cells (N19 OLGs). This study provides the first evidence that laminin (LN) differentially regulates the expression of pS80MeCP2 in immature and mature N19 OLGs. Thus, MeCP2 is phosphorylated in a stimulus-dependent manner during oligodendrocyte development, and thereby, it may regulate the oligodendrocyte behavior.

pERK1/2 Peripheral Recruitment and Filopodia Protrusion Augment Oligodendrocyte Progenitor Cell Migration: Combined Effects of PDGF-A and Fibronectin.

Oligodendrocyte progenitor cell (OPC) migration is critical for effective myelination of the central nervous system. Not only during normal myelination but also during remyelination, the growth factors (GFs) and extracellular matrix (ECM) protein affect the OPC migration. Studies showed the altered levels of GFs and ECM in the demyelinating lesions. In our earlier studies, we have shown that the effect of platelet-derived growth factor alpha (PDGF-A) on OPC migration is dose- and time-dependent. In that we have shown that the physiological concentration (1 ng/ml) of PDGF-A was unable to induce OPC migration at transient exposure (30 min). However, the involvement of ECM in the regulation of PDGF-A mediated OPC migration was not clear. In the present study, we have used fibronectin (FN) as ECM. PDGF-A and FN have similar and overlapping intracellular signaling pathways including the extracellular regulated kinases 1 and 2 (ERK1/2). Here we demonstrate how physiological concentration of PDGF-A combines with FN to augment OPC migration in vitro. The present study is first of its kind to show the importance of the synergistic effects of PDGF-A and FN on peripheral recruitment of phosphorylated/activated ERK1/2 (pERK1/2), actin-pERK1/2 co-localization, and filopodia formation, which are essential for the enhanced OPC migration. These findings were further confirmed by ERK1/2 inhibition studies, using the pharmacological inhibitor U0126. An understanding of these complex interactions may lead to additional strategies for transplanting genetically modified OPCs to repair widespread demyelinated lesions.

Synthesis and Biological Evaluation of Novel Multi-target-Directed Benzazepines Against Excitotoxicity.

Excitotoxicty, a key pathogenic event is characteristic of the onset and development of neurodegeneration. The glutamatergic neurotransmission mediated through different glutamate receptor subtypes plays a pivotal role in the onset of excitotoxicity. The role of NMDA receptor (NMDAR), a glutamate receptor subtype, has been well established in the excitotoxicity pathogenesis. NMDAR overactivation triggers excessive calcium influx resulting in excitotoxic neuronal cell death. In the present study, a series of benzazepine derivatives, with the core structure of 3-methyltetrahydro-3H-benzazepin-2-one, were synthesised in our laboratory and their NMDAR antagonist activity was determined against NMDA-induced excitotoxicity using SH-SY5Y cells. In order to assess the multi-target-directed potential of the synthesised compounds, Aß1-42 aggregation inhibitory activity of the most potent benzazepines was evaluated using thioflavin T (ThT) and Congo red (CR) binding assays as Aß also imparts toxicity, at least in part, through NMDAR overactivation. Furthermore, neuroprotective, free radical scavenging, anti-oxidant and anti-apoptotic activities of the two potential test compounds (7 and 14) were evaluated using primary rat hippocampal neuronal culture against Aß1-42-induced toxicity. Finally, in vivo neuroprotective potential of 7 and 14 was assessed using intracerebroventricular (ICV) rat model of Aß1-42-induced toxicity. All of the synthesised benzazepines have shown significant neuroprotection against NMDA-induced excitotoxicity. The most potent compound (14) showed relatively higher affinity for the glycine binding site as compared with the glutamate binding site of NMDAR in the molecular docking studies. 7 and 14 have been shown experimentally to abrogate Aß1-42 aggregation efficiently. Additionally, 7 and 14 showed significant neuroprotective, free radical scavenging, anti-oxidant and anti-apoptotic properties in different in vitro and in vivo experimental models. Finally, 7 and 14 attenuated Aß1-42-induced tau phosphorylation by abrogating activation of tau kinases, i.e. MAPK and GSK-3ß. Thus, the results revealed multi-target-directed potential of some of the synthesised novel benzazepines against excitotoxicity.

Neuroprotective Potential of Novel Multi-Targeted Isoalloxazine Derivatives in Rodent Models of Alzheimer's Disease Through Activation of Canonical Wnt/ß-Catenin Signalling Pathway.

Previous reports suggest that Alzheimer's disease is protected by cholinesterase inhibitors. We synthesized some isoalloxazine derivatives and evaluated them using in vitro cholinesterase inhibition assay. Two of the compounds (7m and 7q) were figured out as potent cholinesterase inhibitors. They further showed anti-Aß aggregatory activity in the in vitro assay. The current study deals with the evaluation of neuroprotective potentials of the potent compounds (7m and 7q) using different in vitro and in vivo experiments. The compounds were first assessed for their tendency to cross blood-brain barrier using in vitro permeation assay. They were evaluated using scopolamine-induced amnesic mice model. Additionally, ROS scavenging and anti-apoptotic properties of 7m and 7q were established against Aß1-42-induced toxicity in rat hippocampal neuronal cells. 7m and 7q were also evaluated using Aß1-42-induced Alzheimer's rat model. Lastly, their involvement in Wnt/ß-catenin pathway was also demonstrated. The results indicated good CNS penetration for 7m and 7q. The neuroprotective effects of 7m and 7q were evidenced by improved cognitive ability in both scopolamine and Aß1-42-induced Alzheimer's-like condition in rodents. The in vivo results also confirmed their anti-cholinesterase and anti-oxidant potential. Immunoblot results showed that treatment with 7m and 7q decreased Aß1-42, p-tau, cleaved caspase-3, and cleaved PARP levels in Aß1-42-induced Alzheimer's rat brain. Additionally, immunoblot results demonstrated that 7m and 7q activated the Wnt/ß-catenin pathway as evidenced by increased p-GSK-3, ß-catenin, and neuroD1 levels in Aß1-42-induced Alzheimer's rat brain. These findings have shown that isoalloxazine derivatives (7m and 7q) could be the potential leads for developing effective drugs for the treatment of AD.

Involvement of MeCP2 in Regulation of Myelin-Related Gene Expression in Cultured Rat Oligodendrocytes.

Methyl CpG binding protein 2 (MeCP2) is a multifunctional protein which binds to methylated CpG, mutation of which cause a neurodevelopmental disorder, Rett syndrome. MeCP2 can function as both transcriptional activator and repressor of target gene. MeCP2 regulate gene expression in both neuron and glial cells in central nervous system (CNS). Oligodendrocytes, the myelinating cells of CNS, are required for normal functioning of neurons and are regulated by several transcription factors during their differentiation. In current study, we focused on the role of MeCP2 as transcription regulator of myelin genes in cultured rat oligodendrocytes. We have observed expression of MeCP2 at all stages of oligodendrocyte development. MeCP2 knockdown in cultured oligodendrocytes by small interference RNA (siRNA) has shown increase in myelin genes (myelin basic protein (MBP), proteolipid protein (PLP), myelin oligodendrocyte glycoprotein (MOG), and myelin-associated oligodendrocyte basic protein (MOBP)), neurotrophin (brain-derived neurotrophic factor (BDNF)), and transcriptional regulator (YY1) transcripts level, which are involved in regulation of oligodendrocyte differentiation and myelination. Further, we also found that protein levels of MBP, PLP, DM-20, and BDNF also significantly upregulated in MeCP2 knockdown oligodendrocytes. Our study suggests that the MeCP2 acts as a negative regulator of myelin protein expression.

Discovery of isoalloxazine derivatives as a new class of potential anti-Alzheimer agents and their synthesis.

This article describes discovery of a novel and new class of cholinesterase inhibitors as potential therapeutics for Alzheimer's disease. A series of novel isoalloxazine derivatives were synthesized and biologically evaluated for their potential inhibitory outcome for both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). These compounds exhibited high activity against both the enzymes AChE as well as BuChE. Of the synthesized compounds, the most potent isoalloxazine derivatives (7m and 7q) showed IC50 values of 4.72 µM and 5.22 µM respectively against AChE; and, 6.98 µM and 5.29 µM respectively against BuChE. These two compounds were further evaluated for their anti-aggregatory activity for ß-amyloid (Aß) in presence and absence of AChE by performing Thioflavin-T (ThT) assay and Congo red (CR) binding assay. In order to evaluate cytotoxic profile of these two potential compounds, cell viability assay of SH-SY5Y human neuroblastoma cells was performed. Further, to understand the binding behavior of these two compounds with AChE and BuChE enzymes, docking studies have been reported.

Differential effects of growth factors on oligodendrocyte progenitor migration.

Oligodendrocytes are myelinating cells of the CNS that originate as progenitor cells (OP) in discrete areas of the developing brain. During brain development, OP migrate significant distances prior to proliferating and myelinating the axons of the putative white matter tracts. Growth factors play a major regulatory role in the behavior of OP. Specifically, platelet-derived growth factor A (PDGF-A) and fibroblast growth factor 2 (FGF2) are two of the most well characterized regulators of OP development. Both growth factors interact with tyrosine kinase receptors, activating various intracellular signaling pathways. The current study advances our earlier research by comparing the effects of both PDGF-A and FGF2 on OP migration. Our results show that activation of ERK is required for OP migration. These findings correlate well with our previous demonstration of the ERK pathway mediating PDGF-A induced OP migration. We also demonstrate the significance of threshold levels of growth factors and temporal regulation for OP migration. In addition, ERK activation alone is not sufficient to induce OP migration. The current research supports the involvement of the non-ERK mediated signaling pathway in OP migration.

Lead and cadmium co-exposure mediated toxic insults on hepatic steroid metabolism and antioxidant system of adult male rats.

The redox status and steroid metabolism of liver of adult male rat exposed to lead (Pb) and cadmium (Cd) either alone or in co-exposure (0.025 mg/kg body weight intraperitoneally/15 days) was studied. Pb and Cd significantly accumulated in the liver. The activity of steroid metabolizing enzymes 17-betahydroxysteroid oxidoreductase and uridine diphosphate-glucuronyltransferase were decreased in experimental animals. 17-beta-Hydroxysteroid dehydrogenase was reduced to 33%, 38%, and 24% on treatment of Pb, Cd, and co-exposure (Pb + Cd). Furthermore, the activity of uridine diphosphate-glucuronosyltransferase was significantly reduced to 27% (Pb exposure), 36% (Cd exposure), and 25% (co-exposure of Pb + Cd). Cd exposure exhibited more toxic effect than Pb, while co-exposure demonstrated the least. The activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione reductase, and glucose-6-phosphate dehydrogenase decreased and glutathione peroxidase increased in mitochondrial and post-mitochondrial fractions. The level of lipid peroxidation increased, and cellular glutathione concentration decreased. Hepatic DNA was decreased, whereas RNA content and the activity of alanine transaminase remained unchanged. Histological studies revealed that only Cd-exposed groups exhibited cytotoxic effect. These results suggest that when Pb and Cd are present together in similar concentrations, they exhibited relatively decreased toxic effect when compared to lead and cadmium in isolation with regard to decreased steroid metabolizing and antioxidant enzyme activities. This seems that the toxic effect of these metals is antagonized by co-exposure due to possible competition amongst Pb and Cd for hepatic accumulation.