NAT8L mRNA oxidation is linked to neurodegeneration in multiple sclerosis.

RNA oxidation has been implicated in neurodegeneration, but the underlying mechanism for such effects is unclear. Extensive RNA oxidation occurs within the neurons in multiple sclerosis (MS) brains. Here, we identified selectively oxidized mRNAs in neuronal cells that pertained to neuropathological pathways. N-acetyl aspartate transferase 8 like (NAT8L) is one such transcript, whose translation product enzymatically synthesizes N-acetyl aspartic acid (NAA), a neuronal metabolite important for myelin synthesis. We reasoned that impediment of translation of an oxidized NAT8L mRNA will result in a reduction in its cognate protein, thus lowering the NAA level. This hypothesis is supported by our studies on cells, an animal model, and postmortem human MS brain. Reduced brain NAA level hampers myelin integrity making neuronal axons more susceptible to damage, which contributes to MS neurodegeneration. Overall, this work provides a framework for a mechanistic understanding of the link between RNA oxidation and neurodegeneration.

Ibrutinib Resistance Mechanisms and Treatment Strategies for B-Cell lymphomas.

Chronic activation of B-cell receptor (BCR) signaling via Bruton tyrosine kinase (BTK) is largely considered to be one of the primary mechanisms driving disease progression in B-Cell lymphomas. Although the BTK-targeting agent ibrutinib has shown promising clinical responses, the presence of primary or acquired resistance is common and often leads to dismal clinical outcomes. Resistance to ibrutinib therapy can be mediated through genetic mutations, up-regulation of alternative survival pathways, or other unknown factors that are not targeted by ibrutinib therapy. Understanding the key determinants, including tumor heterogeneity and rewiring of the molecular networks during disease progression and therapy, will assist exploration of alternative therapeutic strategies. Towards the goal of overcoming ibrutinib resistance, multiple alternative therapeutic agents, including second- and third-generation BTK inhibitors and immunomodulatory drugs, have been discovered and tested in both pre-clinical and clinical settings. Although these agents have shown high response rates alone or in combination with ibrutinib in ibrutinib-treated relapsed/refractory(R/R) lymphoma patients, overall clinical outcomes have not been satisfactory due to drug-associated toxicities and incomplete remission. In this review, we discuss the mechanisms of ibrutinib resistance development in B-cell lymphoma including complexities associated with genomic alterations, non-genetic acquired resistance, cancer stem cells, and the tumor microenvironment. Furthermore, we focus our discussion on more comprehensive views of recent developments in therapeutic strategies to overcome ibrutinib resistance, including novel BTK inhibitors, clinical therapeutic agents, proteolysis-targeting chimeras and immunotherapy regimens.

Changes in Methionine Metabolism and Histone H3 Trimethylation Are Linked to Mitochondrial Defects in Multiple Sclerosis.

Mitochondrial changes, including decreased expression of electron transport chain subunit genes and impaired energetic, have been reported in multiple sclerosis (MS), but the mechanisms involved in these changes are not clear. To determine whether epigenetic mechanisms are involved, we measured the concentrations of methionine metabolites by liquid chromatography tandem mass spectrometry, histone H3 methylation patterns, and markers of mitochondrial respiration in gray matter from postmortem MS and control cortical samples. We found decreases in respiratory markers as well as decreased concentrations of the methionine metabolites S-adenosylmethionine, betaine, and cystathionine in MS gray matter. We also found expression of the enzyme betaine homocysteine methyltransferase in cortical neurons. This enzyme catalyzes the remethylation of homocysteine to methionine, with betaine as the methyl donor, and has previously been thought to be restricted to liver and kidney in the adult human. Decreases in the concentration of the methyl donor betaine were correlated with decreases in histone H3 trimethylation (H3K4me3) in NeuN+ neuronal nuclei in MS cortex compared with controls. Mechanistic studies demonstrated that H3K4me3 levels and mitochondrial respiration were reduced in SH-SY5Y cells after exposure to the nitric oxide donor sodium nitroprusside, and betaine was able to rescue H3K4me3 levels and respiratory capacity in these cells. Chromatin immunoprecipitation experiments showed that betaine regulates metabolic genes in human SH-SY5Y neuroblastoma cells. These data suggest that changes to methionine metabolism may be mechanistically linked to changes in neuronal energetics in MS cortex. SIGNIFICANCE STATEMENT: For decades, it has been observed that vitamin B12 deficiency and multiple sclerosis (MS) share certain pathological changes, including conduction disturbances. In the present study, we have found that vitamin B12-dependent methionine metabolism is dysregulated in the MS brain. We found that concentrations of the methyl donor betaine are decreased in MS cortex and are correlated with reduced levels of the histone H3 methyl mark H3K4me3 in neurons. Cell culture and chromatin immunoprecipitation-seq data suggest that these changes may lead to defects in mitochondria and impact neuronal energetics. These data have uncovered a novel pathway linking methionine metabolism with mitochondrial respiration and have important implications for understanding mechanisms involved in neurodegeneration in MS.

Mechanism of Nanotization-Mediated Improvement in the Efficacy of Caffeine Against 1-Methyl-4-Phenyl-1,2,3,6-Tetrahydropyridine-Induced Parkinsonism.

The study aimed to measure the neuroprotective efficacy of caffeine-encapsulated poly(lactic-co-glycolic acid) (PLGA) nanoparticles over bulk and to delineate the mechanism of improvement in efficacy both in vitro and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of Parkinsonism. Caffeine-encapsulated PLGA nanoparticles exhibited more pronounced increase in the endurance of dopaminergic neurons, fibre outgrowth and expression of tyrosine hydroxylase (TH) and growth-associated protein-43 (GAP-43) against 1-methyl-4-phenylpyridinium (MPP+)-induced alterations in vitro. Caffeine-encapsulated PLGA nanoparticles also inhibited MPP(+)-mediated nuclear translocation of nuclear factor-kappa B (NF-κB) and augmented protein kinase B phosphorylation more potentially than bulk counterpart. Conversely, MPTP reduced the striatal dopamine and its metabolites and nigral TH immunoreactivity whereas augmented the nigral microglial activation and nigrostriatal lipid peroxidation and nitrite content, which were shifted towards normalcy by caffeine. The modulations were more evident in caffeine-encapsulated PLGA nanoparticles treated animals as compared with bulk. Moreover, the striatal caffeine and its metabolites were found to be significantly higher in caffeine-encapsulated PLGA nanoparticles-treated mice as compared with bulk. The results thus suggest that nanotization improves the protective efficacy of caffeine against MPTP-induced Parkinsonism owing to enhanced bioavailability, inhibition of the nuclear translocation of NF-κB and activation of protein kinase B phosphorylation.

Does restraining nitric oxide biosynthesis rescue from toxins-induced parkinsonism and sporadic Parkinson's disease?

Nitric oxide (NO) is an important inorganic molecule of the biological system owing to diverse physiological implications. NO is synthesised from a semi-essential amino acid L-arginine. NO biosynthesis is catalysed by a family of enzymes referred to as nitric oxide synthases (NOSs). NO is accused in many acute and chronic illnesses, which include central nervous system disorders, inflammatory diseases, reproductive impairments, cancer and cardiovascular anomalies. Owing to very unstable nature, NO gets converted into nitrite, peroxynitrite and other reactive nitrogen species that could lead to nitrosative stress in the nigrostriatal system. Nitrosative stress is widely implicated in Parkinson's disease (PD), and its beneficial and harmful effects are demonstrated in in vitro, rodent and primate models of toxins-induced parkinsonism and in the blood, cerebrospinal fluid and nigrostriatal tissues of sporadic PD patients. The current article updates the roles of NO and NOSs in sporadic PD and toxins-induced parkinsonism in rodents along with the scrutiny of how inhibitors of NOSs could open a new line of approach to moderately rescue from PD pathogenesis based on the existing literature. The article also provides a perspective concerning the lack of ample admiration to such an approach and how to minimise the underlying lacunae.

Silymarin- and melatonin-mediated changes in the expression of selected genes in pesticides-induced Parkinsonism.

Parkinson's disease (PD) is the second most unconcealed neurodegenerative disorder labelled with motor impairments. Two pesticides, manganese ethylene-1,2-bisdithiocarbamate (maneb) and 1,1'-dimethyl-4,4'-bipyridinium dichloride (paraquat), together, are reported to increase the incidence of PD in humans and Parkinsonism in mice. Conversely, silymarin and melatonin, two naturally occurring antioxidants, rescue from maneb- and paraquat-induced Parkinsonism. The study examined silymarin- and melatonin-mediated changes in the expression of selected genes in maneb- and paraquat-induced Parkinsonism employing mouse discover chips microarrays. The mice were treated intraperitoneally (i.p.), daily, with silymarin (40 mg/kg) or melatonin (30 mg/kg) for 9 weeks along with vehicles. Subsets of animals were also treated with maneb (30 mg/kg; i.p.) and paraquat (10 mg/kg; i.p.), twice a week, for 9 weeks. Whilst the expression of genes in the striatum was determined by microarray, the expression of randomly selected transcripts was validated by quantitative real-time polymerase chain reaction (qRT-PCR). Combined maneb- and paraquat-treatment altered the expression of several genes associated with apoptosis, inflammation, cell cycle, cell-signalling, etc. pathways. Silymarin and melatonin significantly resisted the changes in the expression of a few genes related to apoptosis, inflammation, cell cycle, cell-signalling, etc. The expression patterns of seven randomly selected genes were analyzed by qRT-PCR, which were found to follow the similar trends, as observed with microarray. The results obtained from the study thus demonstrate that despite resemblances, silymarin and melatonin differentially offset maneb- and paraquat-induced changes in transcriptome.

Nicotine-encapsulated poly(lactic-co-glycolic) acid nanoparticles improve neuroprotective efficacy against MPTP-induced parkinsonism.

For some instances of Parkinson disease (PD), current evidence in the literature is consistent with reactive oxygen species being involved in the etiology of the disease. The management of PD is still challenging owing to its ambiguous etiology and lack of permanent cure. Because nicotine offers neuroprotection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonism, the neuroprotective efficacy of nicotine-encapsulated poly(lactic-co-glycolic) acid (PLGA) nanoparticles and the underlying mechanism of improved efficacy, if any, over bulk nicotine were assessed in this study. The selected indicators of oxidative stress, dopaminergic neurodegeneration and apoptosis, were measured in both in vitro and rodent models of parkinsonism in the presence or absence of "nanotized" or bulk nicotine. The levels of dopamine and its metabolites were measured in the striatum, nicotine and its metabolite in the nigrostriatal tissues while the immunoreactivities of tyrosine hydroxylase (TH), metallothionein-III (MT-III), inducible nitric oxide synthase (iNOS) and microglial activation were checked in the substantia nigra of controls and treated mice. GSTA4-4, heme oxygenase (HO)-1, tumor suppressor protein 53 (p53), caspase-3, lipid peroxidation (LPO), and nitrite levels were measured in the nigrostriatal tissues. Nicotine-encapsulated PLGA nanoparticles improved the endurance of TH-immunoreactive neurons and the number of fiber outgrowths and increased the mRNA expression of TH, neuronal cell adhesion molecule, and growth-associated protein-43 over bulk against 1-methyl-4-phenyl pyridinium ion-induced degeneration in the in vitro model. MPTP reduced TH immunoreactivity and levels of dopamine and its metabolites and increased microglial activation, expression of GSTA4-4, iNOS, MT-III, HO-1, p53, and caspase-3, and levels of nitrite and LPO. Whereas both bulk nicotine and nicotine-encapsulated PLGA nanoparticles modulated the changes toward controls, the modulation was more pronounced in nicotine-encapsulated PLGA nanoparticle-treated parkinsonian mice. The levels of nicotine and cotinine were elevated in nicotine-encapsulated PLGA nanoparticle-treated PD mouse brain compared with bulk. The results obtained from this study demonstrate that nanotization of nicotine improves neuroprotective efficacy by enhancing its bioavailability and subsequent modulation in the indicators of oxidative stress and apoptosis.

Melatonin as a neuroprotective agent in the rodent models of Parkinson's disease: is it all set to irrefutable clinical translation?

Parkinson's disease (PD), a neurodegenerative disorder, is characterized by the selective degeneration of the nigrostriatal dopaminergic neurons, continuing or permanent deficiency of dopamine, accretion of an abnormal form of alpha synuclein in the adjacent neurons, and dysregulation of ubiquitin proteasomal system, mitochondrial metabolism, permeability and integrity, and cellular apoptosis resulting in rigidity, bradykinesia, resting tremor, and postural instability. Melatonin, an indoleamine produced almost in all the organisms, has anti-inflammatory, anti-apoptotic, and anti-oxidant nature. Experimental studies employing 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine (MPTP), 6-hydroxydopamine (6-OHDA), methamphetamine, rotenone, and maneb and paraquat models have shown an enormous potential of melatonin in amelioration of the symptomatic features of PD. Although a few reviews published previously have described the multifaceted efficacy of melatonin against MPTP and 6-OHDA rodent models, due to development and validation of the newer models as well as the extensive studies on the usage of melatonin in entrenched PD models, it is worthwhile to bring up to date note on the usage of melatonin as a neuroprotective agent in PD. This article presents an update on the usage and applications of melatonin in PD models along with incongruous observations. The impending implications in the clinics, success, limitations, and future prospective have also been discussed in this article.

Melatonin or silymarin reduces maneb- and paraquat-induced Parkinson's disease phenotype in the mouse.

Oxidative stress is reported as one of the most widely accepted mechanisms of maneb (MB)- and paraquat (PQ)-induced nigrostriatal dopaminergic neurodegeneration leading to the Parkinson's disease (PD) phenotype. The study investigated the effects of silymarin, an antioxidant of plant origin, and melatonin, an indoleamine produced in all species, in MB- and PQ-induced mouse model of PD. The mice were treated intraperitoneally daily with silymarin (40mg/kg) or melatonin (30mg/kg) along with respective controls for 9wk. Subsets of these animals were also treated with MB (30mg/kg) and PQ (10mg/kg), twice a week, for 9wk, 2hr after silymarin/melatonin treatment. Locomotor activities along with striatal dopamine content, tyrosine hydroxylase (TH) immunoreactivity, number of degenerating neurons, lipid peroxidation and nitrite content were estimated. Additionally, mRNA expression of vesicular monoamine transporter, cytochrome P-450 2E1 (CYP2E1), and glutathione-S-transferase A4-4 (GSTA4-4), catalytic activities of CYP2E1 and GSTA4-4 and protein expressions of unphosphorylated and phosphorylated p53 (p53 and P-p53), Bax and caspase 9 were measured in control and MB- and PQ-treated mice with either silymarin or melatonin treatments. Silymarin/melatonin significantly offset MB- and PQ-mediated reductions in locomotor activities, dopamine content, TH immunoreactivity, VMAT 2 mRNA expression and the expression of p53 protein. Silymarin/melatonin attenuated the increases in lipid peroxidation, number of degenerating neurons, nitrite content, mRNA expressions of cytochrome P-450 2E1 (CYP2E1) and GSTA4-4, catalytic activities of CYP2E1 and GST and P-p53, Bax and caspase 9 protein expressions. The results demonstrate that silymarin and melatonin offer nigrostriatal dopaminergic neuroprotection against MB- and PQ-induced PD by the modulation of oxidative stress and apoptotic machinery.

Nicotine- and caffeine-mediated changes in gene expression patterns of MPTP-lesioned mouse striatum: Implications in neuroprotection mechanism.

Exposure to 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP) induces dopaminergic neurodegeneration in the nigrostriatal pathway and nicotine and caffeine ameliorate neurodegenerative changes in MPTP-lesioned mouse model of Parkinson's disease (PD). The present study was undertaken to investigate the effect of nicotine and caffeine on the expression patterns of genes in the striatum of control and MPTP-treated mice to identify the differentially expressed transcripts and to assess their possible implications in neuroprotection. Mice were treated intraperitoneally with caffeine (20mg/kg) or nicotine (1mg/kg), daily, for the first 8 weeks followed by MPTP (20mg/kg) co-treatment for further 4 weeks along with respective controls. RNA was isolated from the striatum of control and treated mice; reverse transcribed separately into labeled cDNA and a mixture of equal quantities of labeled cDNA was hybridized with mouse 15k array. The expression levels of toll-interleukin-1 receptor domain-containing adaptor protein, nuclear protein-1, cathepsin B, interleukin-4 receptor, caspase 9, complement component-1, heat shock protein-1 and cytochrome c-oxidase-VIIc were validated by quantitative real-time polymerase chain reaction (qRT-PCR). MPTP differentially regulated the expression of many genes involved in apoptotic cell death, oxidative stress, cell cycle regulation, protein modification and mitochondrial dysfunction. The expression patterns of many of these transcripts were significantly restored in caffeine- and nicotine-treated mice. The results demonstrate the involvement of multiple molecular events in MPTP-induced toxicity and nicotine or caffeine-mediated neuroprotection.

Omics in mechanistic and predictive toxicology.

High-throughput omics strategies delineate the molecular mechanism of toxicity, predict the toxicity of newer drugs and chemicals, and identify individuals at high risks on the basis of expression patterns of messenger ribonucleic acids, genes, and proteins, and detection of intermediary metabolites. Despite being a developing country, India is one of the fastest growing nations in the usages and applications of omics technologies. Several differentially expressed genes and proteins under various pathological and toxicant-exposed conditions have been identified, and many association studies on genetic polymorphisms with toxicant-induced diseases have been conducted for the predictive and mechanistic purposes. To date, omics-driven approaches have identified some novel fingerprints associated with disease risk/protection and prediction of toxicity of newer chemicals. Although the contributions of such findings in the mechanistic toxicology have been immense, predictive values of these findings in toxicology have been limited. In this review, the current status of omics-based research and its future possibilities at the Indian Institute of Toxicology Research (IITR), Lucknow, India, have been discussed.

Association of single nucleotide polymorphisms in CYP1B1 and COMT genes with breast cancer susceptibility in Indian women.

Cytochrome P450 1B1 (CYP1B1) and catechol-O-methyltransferase (COMT) enzymes play critical roles in estrogen metabolism. Alterations in the catalytic activity of CYP1B1 and COMT enzymes have been found associated with altered breast cancer risk in postmenopausal women in many populations. The substitution of leucine (Leu) to valine (Val) at codon 432 increases the catalytic activity of CYP1B1, however, substitution of Val to methionine (Met) at codon 158 decreases the catalytic activity of COMT. The present study was performed to evaluate the associations of CYP1B1 Leu(432)Val and/or COMT Val(158)Met polymorphisms with total, premenopausal and postmenopausal breast cancer risks in Indian women. COMT and CYP1B1 polymorphisms in controls and breast cancer patients were analyzed employing polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) followed by gel electrophoresis. Although CYP1B1 and COMT genotypes did not exhibit statistically significant association with breast cancer risks when analyzed individually, COMT wild type (Val(158)Val) in combination with CYP1B1 heterozygous variant (Leu(432)Val) [OR: 0.21; 95% CI (0.05-0.82), p value; 0.021] and COMT heterozygous variant (Val(158)Met) in combination with CYP1B1 wild type (Leu(432)Leu) [OR: 0.29; 95% CI (0.08-0.96), p value; 0.042] showed significant protective association with premenopausal breast cancer risk. The results demonstrate that CYP1B1 wild type in combination with COMT heterozygous or their inverse combination offer protection against breast cancer in premenopausal Indian women.