Global DNA methylation profiling of manganese-exposed human neuroblastoma SH-SY5Y cells reveals epigenetic alterations in Parkinson’s disease-associated genes

Manganese (Mn) is an essential trace element required for optimal functioning of cellular biochemical pathways in the central nervous system. Elevated exposure to Mn through environmental and occupational exposure can cause neurotoxic effects resulting in manganism, a condition with clinical symptoms identical to idiopathic Parkinson’s disease. Epigenetics is now recognized as a biological mechanism involved in the etiology of various diseases. Here, we investigated the role of DNA methylation alterations induced by chronic Mn (100 µM) exposure in human neuroblastoma (SH-SY5Y) cells in relevance to Parkinson’s disease. A combined analysis of DNA methylation and gene expression data for Parkinson’s disease-associated genes was carried out. Whole-genome bisulfite conversion and sequencing indicate epigenetic perturbation of key genes involved in biological processes associated with neuronal cell health. Integration of DNA methylation data with gene expression reveals epigenetic alterations to PINK1, PARK2 and TH genes that play critical roles in the onset of Parkinsonism. The present study suggests that Mn-induced alteration of DNA methylation of PINK1–PARK2 may influence mitochondrial function and promote Parkinsonism. Our findings provide a basis to further explore and validate the epigenetic basis of Mn-induced neurotoxicity

Manganese exposure: linking down-regulation of miRNA-7 and miRNA-433 with α-synuclein overexpression and risk of idiopathic Parkinson's disease

Manganese is an essential trace element however elevated environmental and occupational exposure to this element has been correlated with neurotoxicity symptoms clinically identical to idiopathic Parkinson's disease. In the present study we chronically exposed human neuroblastoma SH-SY5Y cells to manganese (100 μM) and carried out expression profiling of miRNAs known to modulate neuronal differentiation and neurodegeneration. The miRNA PCR array results reveal alterations in expression levels of miRNAs, which have previously been associated with the regulation of synaptic transmission and apoptosis. The expressions of miR-7 and miR-433 significantly reduced upon manganese exposure. By in silico homology analysis we identified SNCA and FGF-20as targets of miR-7 and miR-433. We demonstrate an inverse correlation in expression levels where reduction in these two miRNAs causes increases in SNCA and FGF-20. Transient transfection of SH-SY5Y cells with miR-7 and miR-433 mimics resulted in down regulation of SNCA and FGF-20 mRNA levels. Our study is the first to uncover the potential link between manganese exposure, altered miRNA expression and parkinsonism: manganese exposure causes overexpression of SNCA and FGF-20 by diminishing miR-7 and miR-433 levels. These miRNAs may be considered critical for protection from manganese induced neurotoxic mechanism and hence as potential therapeutic targets

Beta caryophyllene and caryophyllene oxide, isolated from Aegle marmelos, as the potent anti-inflammatory agents against lymphoma and neuroblastoma cells

Aegle Marmelos (Indian Bael) is a tree belonging to the family of Rutaceae. It holds a prominent position in both Indian medicine and culture. We have screened various fractions of Aegle marmelos extracts for its anti-cancer properties using in vitro cell models. Gas chromatography-Mass spectrometry (GC-MS) was employed to analyze the biomolecules present in the Aegle marmelos extract. Jurkat and human neuroblastoma (IMR-32) cells were treated with different concentrations of the fractionated Aegle marmelos extracts. Flow cytometric analysis revealed that optimal concentration (170µg/ml) of beta caryophyllene and caryophyllene oxide fractions of Aegle marmelos extract can induce apoptosis in Jurkat cell line. cDNA expression profiling of pro-apoptotic and anti-apoptotic genes was carried out using real time PCR (RT-PCR). Down-regulation of anti-apoptotic genes (bcl-2, mdm2, cox2 and cmyb) and up-regulation of pro-apoptotic genes (bax, bak1, caspase-8, caspase-9 and ATM) in Jurkat and IMR-32 cells treated with the beta caryophyllene and caryophyllene oxide fractions of Aegle marmelos extract revealed the insights of the downstream apoptotic mechanism. Furthermore, in-silico approach was employed to understand the upstream target involved in the induction of apoptosis by the beta caryophyllene and caryophyllene oxide fractions of Aegle marmelos extract. Herein, we report that beta caryophyllene and caryophyllene oxide isolated from Aegle marmelos can act as the potent anti-inflammatory agents and modulators of a newly established therapeutic target, 15-lypoxygenase (15-LOX). Beta caryophyllene and caryophyllene oxide can induce apoptosis in lymphoma and neuroblastoma cells via modulation of 15-LOX (up-stream target) followed by the down-regulation of anti-apoptotic and up-regulation of pro-apoptotic genes

Noncoding RNAs: Possible Players in the Development of Fluorosis

Fluorosis is caused by excess of fluoride intake over a long period of time. Aberrant change in the Runt-related transcription factor 2 (RUNX2) mediated signaling cascade is one of the decisive steps during the pathogenesis of fluorosis. Up to date, role of fluoride on the epigenetic alterations is not studied. In the present study, global expression profiling of short noncoding RNAs, in particular miRNAs and snoRNAs, was carried out in sodium fluoride (NaF) treated human osteosarcoma (HOS) cells to understand their possible role in the development of fluorosis. qPCR and in silico hybridization revealed that miR-124 and miR-155 can be directly involved in the transcriptional regulation of Runt-related transcription factor 2 (RUNX2) and receptor activator of nuclear factor \uce\uba-B ligand (RANKL) genes. Compared to control, C/D box analysis revealed marked elevation in the number of UG dinucleotides and D-box sequences in NaF exposed HOS cells. Herein, we report miR-124 and miR-155 as the new possible players involved in the development of fluorosis. We show that the alterations in UG dinucleotides and D-box sequences of snoRNAs could be due to NaF exposure