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.

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.

Potential role of NGF, BDNF, and their receptors in oligodendrocytes differentiation from neural stem cell: An in vitro study.

Neural stem cells (NSCs) or neuronal progenitor cells are cells capable of differentiating into oligodendrocytes, myelin-forming cells that have the potential of remyelination. Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are two neurotrophic factors that have been studied to stimulate NSC differentiation thus playing a role in multiple sclerosis pathogenesis and several other demyelinating disorders. While several studies have demonstrated the proliferative and protective capabilities of these neurotrophic factors, their cellular and molecular functions are still not well understood. Thus, in the present study, we focus on understanding the role of these neurotrophins (BDNF and NGF) in oligodendrogenesis from NSCs. Both neurotrophic factors have been shown to promote NSC proliferation and NSC differentiation particularly into oligodendroglial lineage in a dose-dependent fashion. Further, to establish the role of these neurotrophins in NSC differentiation, we have employed pharmacological inhibitors for TrkA and TrkB receptors in NSCs. The use of these inhibitors suppressed NSC differentiation into oligodendrocytes along with the downregulation of phosphorylated ERK suggesting active involvement of ERK in the functioning of these neurotrophins. The morphometric analysis also revealed the important role of both neurotrophins in oligodendrocytes development. These findings highlight the importance of neurotrophic factors in stimulating NSC differentiation and may pave a role for future studies to develop neurotrophic factor replacement therapies to achieve remyelination.

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.

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.

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.

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.

A high-throughput image-based screen for the identification of Bax/Bak-independent caspase activators against drug-resistant cancer cells.

Despite the use of new generation target specific drugs or combination treatments, drug-resistance caused by defective apoptosis signaling remains a major challenge in cancer treatment. A common apoptotic defect in drug-resistant tumor is the failure of cancer cells to undergo Bax/Bak-dependent mitochondrial permeabilization due to impaired signaling of Bcl-2 family proteins. Therefore, Bax and Bak-independent caspase-activating compounds appear to be effective in killing such tumor cells. An image-based cellular platform of caspase sensors in Bax and Bak deficient background allowed us to identify several potential Bax/Bak-independent caspase-activating compounds from a limited high-throughput compound screening. FRET-based caspase sensor probe targeted at the nucleus enabled accurate and automated segmentation, yielding a Z-value of 0.72. Some of the positive hits showed promising activity against drug-resistant human cancer cells expressing high levels of Bcl-2 or Bcl-xL. Using this approach, we describe thiolutin, CD437 and TPEN as the most potentially valuable drug candidates for addressing drug-resistance caused by aberrant expression of Bcl-2 family proteins in tumor cells. The screen also enables the quantification of multiparameter apoptotic events along with caspase activation in HTS manner in live mode, allowing characterization of non-classical apoptosis signaling.

The role of dorsal root ganglia activation and brain-derived neurotrophic factor in multiple sclerosis.

Multiple sclerosis (MS) is characterized by focal destruction of the white matter of the brain and spinal cord. The exact mechanisms underlying the pathophysiology of the disease are unknown. Many studies have shown that MS is predominantly an autoimmune disease with an inflammatory phase followed by a demyelinating phase. Recent studies alongside current treatment strategies, including glatiramer acetate, have revealed a potential role for brain-derived neurotrophic factor (BDNF) in MS. However, the exact role of BDNF is not fully understood. We used the experimental autoimmune encephalomyelitis (EAE) model of MS in adolescent female Lewis rats to identify the role of BDNF in disease progression. Dorsal root ganglia (DRG) and spinal cords were harvested for protein and gene expression analysis every 3 days post-disease induction (pdi) up to 15 days. We show significant increases in BDNF protein and gene expression in the DRG of EAE animals at 12 dpi, which correlates with peak neurological disability. BDNF protein expression in the spinal cord was significantly increased at 12 dpi, and maintained at 15 dpi. However, there was no significant change in mRNA levels. We show evidence for the anterograde transport of BDNF protein from the DRG to the dorsal horn of the spinal cord via the dorsal roots. Increased levels of BDNF within the DRG and spinal cord in EAE may facilitate myelin repair and neuroprotection in the CNS. The anterograde transport of DRG-derived BDNF to the spinal cord may have potential implications in facilitating central myelin repair and neuroprotection.

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.

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.

Emerging Concepts on the Role of Extracellular Vesicles and Its Cargo Contents in Glioblastoma-Microglial Crosstalk.

Glioblastoma multiforme is the most common, highly aggressive malignant brain tumor which is marked by highest inter- and intra-tumoral heterogeneity. Despite, immunotherapy, and combination therapies developed; the clinical trials often result into large number of failures. Often cancer cells are known to communicate with surrounding cells in tumor microenvironment (TME). Extracellular vesicles (EVs) consisting of diverse cargo mediates this intercellular communication and is believed to modulate the immune function against GBM. Tumor-associated microglia (TAM), though being the resident innate immune cell of CNS, is known to attain pro-tumorigenic M2 phenotype, and this immunomodulation is aided by extracellular vesicle-mediated transfer of oncogenic, immunomodulatory molecules. Besides, oncogenic proteins, long non-coding RNAs (lncRNAs), are believed to carry oncogenic potential, and therefore, understanding the mechanism leading to microglial dysregulation mediated by GBM-derived extracellular vesicle (GDEV) lncRNAs becomes crucial. This review focuses on current understanding of role of GDEV and lncRNA in microglial dysfunction and its potential as a therapeutic target.

Quantitative Analysis of Apoptosis and Necrosis in Live Cells Using Flow Cytometry.

Apoptosis and necrosis are the two sides of the cell death penumbra. Apoptosis is a well-studied model of cell death wherein the cell destroys itself employing a predefined form of active signaling without the release of soluble cytoplasmic contents to the external environment. Compared to apoptosis, necrosis is a nonspecific form of sudden cell death in response to an invasive external stimulus which in turn is devoid of active programmed intracellular signaling leading to the sudden release of the soluble cellular contents consequent to the rupture of the cell membrane. This fundamental difference between apoptosis and necrosis made us believe that the former is the safe form of cell death and the latter is an undesirable one which often elicits an inflammatory response to the adjacent cells. Recent studies have shown that necrosis also involves a few defined cellular and complex biochemical events similar to apoptosis rendering it difficult to distinguish these two events at the single-cell level using the currently used popular assays.Here we provide a newly described detailed methodology encompassing cell system development along with a multiparametric flow cytometry-based approach to discriminate apoptotic cells from necrotic cells using a stable cell line expressing genetically encoded probe for detecting caspase activation and DsRed targeted at the mitochondria.

HIV TAT-mediated microglial senescence: Role of SIRT3-dependent mitochondrial oxidative stress.

The advent of combined antiretroviral treatment (cART) as a treatment for HIV-1 infection has not only resulted in a dramatic decrease in the peripheral viral load but has also led to increased life expectancy of the infected individuals. Paradoxically, increased lifespan is accompanied with higher prevalence of age-related comorbidities, including HIV-associated neurocognitive disorders (HAND). Present study was aimed at exploring the role of HIV TAT protein in mediating microglial mitochondrial oxidative stress, ultimately resulting in neuroinflammation and microglial senescence. Our findings demonstrated that exposure of mouse primary microglial cells (mPMs) to HIV TAT protein resulted in a senescence-like phenotype, that was characterized by elevated expression of both p16 and p21 proteins, increased numbers of senescence-associated-ß-galactosidase positive cells, augmented cell-cycle arrest, increased release of proinflammatory cytokines and decreased telomerase activity. Additionally, exposure of mPMs to HIV TAT also resulted downregulation of SIRT3 with a concomitant increase in mitochondrial oxidative stress. Dual luciferase reporter assay identified miR-505 as a novel target of SIRT3, which was upregulated in mPMs exposed to HIV TAT. Furthermore, transient transfection of mPMs with either the SIRT3 plasmid or miRNA-505 inhibitor upregulated the expression of SIRT3 and mitochondrial antioxidant enzymes, with a concomitant decrease in microglial senescence. These in vitro findings were also validated in the prefrontal cortices and striatum of HIV transgenic rats as well as cART-treated HIV-infected individuals. In summary, this study underscores a yet undiscovered novel mechanism(s) underlying HIV TAT-mediated induction of senescence phenotype in microglia, involving the miR-505-SIRT3 axis-mediated induction of mitochondrial oxidative stress.

Biochemical and molecular effects of gestational and lactational coexposure to lead and cadmium on ovarian steroidogenesis are associated with oxidative stress in F1 generation rats.

Few studies have characterized the molecular and biochemical mechanisms involved in ovarian steroidogenesis disruption by heavy metals, such as lead and cadmium coexposure, on F1 generation offspring. In this study, adult pregnant female rats were treated subcutaneously (0.05 mg/kg of body weight per day) with sodium acetate (control), lead acetate, and cadmium acetate separately and in combination throughout gestational and lactational period, and all animals from each of the experimental groups were sacrificed by decapitation on postnatal day 56 for various assays. The activities of key steroidogenic enzymes (17ß-hydroxysteroid dehydrogenase and 3ß-hydroxysteroid dehydrogenase) decreased in all the metal-treated groups. But the most significant decrease in the activities was observed in the cadmium-treated group, whereas the combined exposure group showed an intermediate effect. Serum estradiol and progesterone levels were also significantly altered in all the metal-treated groups, with the cadmium-exposed group showing maximum reductions as compared with the control group. The inhibitory effects of lead and cadmium on ovarian steroidogenic acute regulatory protein (StAR) mRNA levels along with CYP11 mRNA levels were also observed. Ovarian cholesterol content measured also showed significant depletion in all the metal-treated groups, with the cadmium-exposed group showing the maximum depletion. The activities of ovarian enzymatic antioxidants, such as superoxide dismutase, catalase, and glutathione peroxidase, were all significantly diminished along with significant depletion in nonenzymatic antioxidants. Lipid peroxidation was elevated significantly in all the metal-treated groups. In conclusion, lead and cadmium inhibit ovarian steroidogenesis by downregulating StAR gene expression along with inhibiting activities of steroidogenic enzymes and antioxidant system.

A reporter cell line for real-time imaging of autophagy and apoptosis.

Simultaneous detection of autophagy and apoptosis is important in drug discovery and signaling studies. Here we report, a real-time reporter cell line for the simultaneous detection of apoptosis and autophagy at single-cell level employing stable integration of two fluorescent protein reporters of apoptosis and autophagy. Cells stably expressing EGFP-LC3 fusion was developed initially as a marker for autophagy and subsequently stably expressed with inter-mitochondrial membrane protein SMAC with RFP fusion to detect mitochondrial permeabilization event of apoptosis. The cell lines faithfully reported the LC3 punctae formation and release of intermembrane proteins in response to diverse apoptotic and autophagic stimuli.

Sex-specific effects of gestational and lactational coexposure to lead and cadmium on hepatic phase I and phase II xenobiotic/steroid-metabolizing enzymes and antioxidant status.

Liver has evolved complex enzymatic mechanisms to detoxify a wide array of xenobiotic substances, ranging from dietary components to environmental toxins to pharmaceuticals. Activities of many steroid-metabolizing enzymes in adult rat liver microsomes are sexually differentiated. Toxic effects of lead and cadmium on hepatic tissue have been well established in our earlier studies. We thus monitored the effects of gestational and lactational coexposure to lead and cadmium on hepatic phase I and phase II xenobiotic- and steroid-metabolizing enzyme activities in both male and female F1 generation postnatal day (PND) 56 rats. Adult pregnant female rats were treated subcutaneously [0.05 mg/(kg body wt. day)] with sodium acetate (control group), lead acetate, and cadmium acetate separately and in combination throughout the gestational and lactational period. Hepatic phase I xenobiotic-metabolizing enzymes (NADPH- and NADH-cytochrome c reductase) activities significantly decreased significantly in all the metal-treated groups in both PND 56 male and female rats as compared with the control group. Hepatic phase II enzymes (uridine diphosphate-glucuronosyl transferase, gamma-glutamyl transpeptidase, glutathione-S-transferase, 17-beta-hydroxysteroid oxidoreductase) were also highly susceptible to all the metal-treated groups. The observed alterations in the oxidative stress and biochemical parameters in the liver of F1 generation male and female rats resulted from an independent effect of lead and/or cadmium and also from their interaction. Results suggest that early developmental exposure to lead and cadmium both alone and in combination can suppress the hepatic xenobiotic-metabolizing enzyme activities in the liver of F1 generation male and female rats in a sex-dependent manner.

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.

Mitochondrial Electron Transport Chain Complex Dysfunction in MeCP2 Knock-Down Astrocytes: Protective Effects of Quercetin Hydrate.

Astrocytes play the central role in CNS metabolism to support neuronal functions. Mehyl-CpG-binding protein 2 (MeCP2) is the global transcription factor with differential expression in neuronal and non-neuronal cells. MeCP2 mutation and downstream detrimental effects have been reported in astrocytes also in MeCP2-associated neurodevelopmental disorder-Rett syndrome. Several studies have shown mitochondrial impairment linked to ROS production and reduced ATP synthesis in Rett patients and models, but consequences of MeCP2 deficiency on mitochondrial electron transport chain complexes in astrocytes and effect of known antioxidant quercetin aglycone has not yet been reported. The present study aimed to investigate effect of quercetin on mitochondrial functioning in MeCP2-deficient astrocytes. Our data show onefold upregulated Uqcrc1 and Ndufv2 gene expression, subtle change in protein expression, and significantly reduced mitochondrial respiratory chain complex-II and complex-III enzyme activities in MeCP2 knock-down astrocytes. Intracellular calcium robustly increased and mitochondrial membrane potential decreased, while no change in ROS was observed in MeCP2 knock-down astrocytes. Quercetin increased MeCP2 and normalized Uqcrc1 and Ndufv2 gene expression but did not modulate MeCP2 and Ndufv2 proteins expression. Interestingly, quercetin upregulated significantly the mitochondrial respiratory complex-II, complex-III, and complex-IV activities in dose-dependent manner. It also restored intracellular calcium level and mitochondrial membrane potential. In vitro observations suggest the beneficial effect of quercetin in mitochondrial functioning in MeCP2-deficient condition. There are no reports focusing on role of quercetin in mitochondrial function in MeCP2-deficient astrocytes, and these observations serve as preliminary data to evaluate quercetin's effects in vivo.