These authors contributed equally to this work.Keywords: autophagy, aging, a-synuclein, dopaminergic neuron loss, motor dysfunction, neurodegeneration, Parkinson's disease, SpermidineAs our society ages, neurodegenerative disorders like Parkinson`s disease (PD) are increasing in pandemic proportions. While mechanistic understanding of PD is advancing, a treatment with well tolerable drugs is still elusive. Here, we show that administration of the naturally occurring polyamine spermidine, which declines continuously during aging in various species, alleviates a series of PD-related degenerative processes in the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, two established model systems for PD pathology. In the fruit fly, simple feeding with spermidine inhibited loss of climbing activity and early organismal death upon heterologous expression of human a-synuclein, which is thought to be the principal toxic trigger of PD. In this line, administration of spermidine rescued a-synuclein-induced loss of dopaminergic neurons, a hallmark of PD, in nematodes. Alleviation of PD-related neurodegeneration by spermidine was accompanied by induction of autophagy, suggesting that this cytoprotective process may be responsible for the beneficial effects of spermidine administration.

Endocrine-disrupting chemicals (EDCs) are man-made chemicals that interfere with hormonal signalling pathways. They are used in, for example, production of common household materials, in resin-based medical supplies and in pesticides. Thus, they are environmentally ubiquitous and human beings and wildlife are exposed to them on a daily basis. Early-life exposure to EDCs has been associated with later-life adversities such as obesity, diabetes and cancer. Mechanisms underlying such associations are unknown but are likely to be mediated by epigenetic changes induced by EDCs. Epigenetics is the study of changes in gene function that are heritable but do not entail a change in DNA sequence. EDCs have been shown to affect epigenetic marks such as DNA methylation and histone modifications. The scope of this article was to review today's knowledge about mechanisms involved in EDC-induced epigenetic changes and to discuss how this knowledge could be used for designing novel methods addressing epigenetic effects of EDCs.Since the industrial revolution, there has been a constant release of chemicals into the environment, which is linked to the increase of various health problems. A group of such environmental chemicals are endocrine-disrupting chemicals (EDCs) that interfere with the hormonal system. EDCs include a wide range of chemicals such as drugs, pesticides, plastic softeners, flame retardants. Thus, human beings and wildlife are exposed to these compounds on a daily basis, and EDCs are detectable in various body fluids [1,2].Increasing evidence suggests that EDC exposure during early life, in particular during foetal development, contributes to a variety of later-life adversaries, from cancer to cognitive impairments [3][4][5]. For instance, the synthetic oestrogen diethylstilbestrol (DES), which was given to women in the 1940s-1970s during early pregnancy to prevent miscarriages, increased the risk of a rare vaginal clear cell adenocarcinoma and infertility in the daughters (DES daughters) [6,7]. And even in the second-generation, adverse effects of DES have been reported. For example, the sons of DES daughters have increased risk of hypospadias, an abnormality of the male reproductive system [8]. It is not fully clear how chemical exposure during early development leads to persistent changes that manifest as diseases much later in life, or even in the next generation. However, increasing evidence points towards a central role for epigenetic mechanisms in these long-lasting effects of EDCs and other chemicals. Epigenetic mechanisms are responsible for permanent transcriptional regulation, and epigenetic changes can be defined as 'any long-term change in gene function that persists even when the initial trigger is long gone and that does not involve a change in gene sequence or structure' [9]. In recent years, a wealth of experimental studies and some evidence from epidemiology have demonstrated that EDCs indeed induce epigenetic changes [10].There is increasing concern in society that developmental expo...

Bisphenol A (BPA), an abundant endocrine disruptor, affects stress-responsiveness and related behaviors in children. In rats, perinatal BPA exposure modifies stress response in pubertal offspring via unknown mechanisms. Here we examined possible epigenetic modifications in the glucocorticoid receptor gene and its regulator Fkbp5 in hypothalamus and hippocampus of exposed offspring. We found increased DNA methylation of Fkbp5 and reduced protein levels in the hippocampus of exposed male rats. Similar effects were obtained in a male hippocampal cell line when exposed to BPA during differentiation. The estrogen receptor (ER) antagonist ICI 182,780 or ERβ knock-down affected Fkbp5 expression and methylation similarly to BPA. Further, BPA's effect on Fkbp5 was abolished upon knock-down of ERβ, suggesting a role for this receptor in mediating BPA's effects on Fkbp5. These data demonstrate that developmental BPA exposure modifies Fkbp5 methylation and expression in male rats, which may be related to its impact on stress responsiveness.

BackgroundProstaglandins (PGs), lipid autacoids derived from arachidonic acid, play a pivotal role during inflammation. PGD2 synthase is abundantly expressed in heart tissue and PGD2 has recently been found to induce cardiomyocyte apoptosis. PGD2 is an unstable prostanoid metabolite; therefore the objective of the present study was to elucidate whether its final dehydration product, 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2, present at high levels in ischemic myocardium) might cause cardiomyocyte damage.Methods and resultsUsing specific (ant)agonists we show that 15d-PGJ2 induced formation of intracellular reactive oxygen species (ROS) and phosphorylation of p38 and p42/44 MAPKs via the PGD2 receptor DP2 (but not DP1 or PPARγ) in the murine atrial cardiomyocyte HL-1 cell line. Activation of the DP2-ROS-MAPK axis by 15d-PGJ2 enhanced transcription and translation of TNFα and induced apoptosis in HL-1 cardiomyocytes. Silencing of TNFα significantly attenuated the extrinsic (caspase-8) and intrinsic apoptotic pathways (bax and caspase-9), caspase-3 activation and downstream PARP cleavage and γH2AX activation. The apoptotic machinery was unaffected by intracellular calcium, transcription factor NF-κB and its downstream target p53. Of note, 9,10-dihydro-15d-PGJ2 (lacking the electrophilic carbon atom in the cyclopentenone ring) did not activate cellular responses. Selected experiments performed in primary murine cardiomyocytes confirmed data obtained in HL-1 cells namely that the intrinsic and extrinsic apoptotic cascades are activated via DP2/MAPK/TNFα signaling.ConclusionsWe conclude that the reactive α,β-unsaturated carbonyl group of 15d-PGJ2 is responsible for the pronounced upregulation of TNFα promoting cardiomyocyte apoptosis. We propose that inhibition of DP2 receptors could provide a possibility to modulate 15d-PGJ2-induced myocardial injury.

Bisphenol A (BPA) exposure has been linked to neurodevelopmental disorders and to effects on epigenetic regulation, such as DNA methylation, at genes involved in brain function. High doses of BPA have been shown to change expression and regulation of one such gene, Grin2b, in mice. Yet, if such changes occur at relevant doses in animals and humans has not been addressed. We investigated if low-dose developmental BPA exposure affects DNA methylation and expression of Grin2b in brains of adult rats. Furthermore, we assessed associations between prenatal BPA exposure and Grin2b methylation in 7-year old children. We found that Grin2b mRNA expression was increased and DNA methylation decreased in female, but not in male rats. In humans, prenatal BPA exposure was associated with increased methylation levels in girls. Additionally, low APGAR scores, a predictor for increased risk for neurodevelopmental diseases, were associated with higher Grin2b methylation levels in girls. Thus, we could link developmental BPA exposure and low APGAR scores to changes in the epigenetic regulation of Grin2b, a gene important for neuronal function, in a sexual dimorphic fashion. Discrepancies in exact locations and directions of the DNA methylation change might reflect differences between species, analysed tissues, exposure level and/or timing.

Background Gabapentin is a structural analog of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Its anticonvulsant, analgesic and anxiolytic properties suggest that it increases GABAergic inhibition; however, the molecular basis for these effects is unknown as gabapentin does not directly modify GABA type A (GABA A ) receptor function, nor does it modify synaptic inhibition. Here, we postulated that gabapentin increases expression of δ subunit-containing GABA A (δGABA A ) receptors that generate a tonic inhibitory conductance in multiple brain regions including the cerebellum and hippocampus. Methods Cell-surface biotinylation, Western blotting, electrophysiologic recordings, behavioral assays, high-performance liquid chromatography and gas chromatography-mass spectrometry studies were performed using mouse models. Findings Gabapentin enhanced expression of δGABA A receptors and increased a tonic inhibitory conductance in neurons. This increased expression likely contributes to GABAergic effects as gabapentin caused ataxia and anxiolysis in wild-type mice but not δ subunit null-mutant mice. In contrast, the antinociceptive properties of gabapentin were observed in both genotypes. Levels of GABA A receptor agonists and neurosteroids in the brain were not altered by gabapentin. Interpretation These results provide compelling evidence to account for the GABAergic properties of gabapentin. Since reduced expression of δGABA A receptor occurs in several disorders, gabapentin may have much broader therapeutic applications than is currently recognized. Fund Supported by a Foundation Grant (FDN-154312) from the Canadian Institutes of Health Research (to B.A.O.); a NSERC Discovery Grant (RGPIN-2016-05538), a Canada Research Chair in Sensory Plasticity and Reconsolidation, and funding from the University of Toronto Centre for the Study of Pain (to R.P.B.).

Following microbial pathogen invasion, the human immune system of activated phagocytes generates and releases the potent oxidant hypochlorous acid (HOCl), which contributes to the killing of menacing microorganisms. Though tightly controlled, HOCl generation by the myeloperoxidase-hydrogen peroxide-chloride system of neutrophils/monocytes may occur in excess and lead to tissue damage. It is thus of marked importance to delineate the molecular pathways underlying HOCl cytotoxicity in both microbial and human cells. Here, we show that HOCl induces the generation of reactive oxygen species (ROS), apoptotic cell death and the formation of specific HOCl-modified epitopes in the budding yeast Saccharomyces cerevisiae. Interestingly, HOCl cytotoxicity can be prevented by treatment with ROS scavengers, suggesting oxidative stress to mediate the lethal effect. The executing pathway involves the pro-apoptotic protease Kex1p, since its absence diminishes HOCl-induced production of ROS, apoptosis and protein modification. By characterizing HOCl-induced cell death in yeast and identifying a corresponding central executor, these results pave the way for the use of Saccharomyces cerevisiae in HOCl research, not least given that it combines both being a microorganism as well as a model for programmed cell death in higher eukaryotes.

Evidence is accumulating that developmental exposure to Bisphenol A (BPA), an abundant endocrine disrupting chemical (EDC), affects neurodevelopment and later brain function, including cognitive performance, social and affective behaviors. However, an impact of BPA exposure on the stress system regulators has only recently come into focus. This mini-review aims to summarize and discuss the available findings from animal studies regarding BPA effects on the stress system and the hypothalamic-pituitary-adrenal (HPA) axis in particular. It appears that perinatal exposure of rodents to low doses of BPA, around the human tolerable daily intake, can modify the levels, expression and epigenetic patterning of key stress mediators at later-life stages in a sex-specific way. These observations provide evidence that developmental exposure to one of the most highly produced chemicals today may contribute to the regulation of the stress axis. Given the importance of the HPA axis in coordination of the organisms' global homeostasis and its implications in stressrelated disorders, further studies are needed to delineate the underling mechanisms of these BPA actions.