No abstract

Regulation of Arpc3 by miRNA alters dendritic spine morphology.

BackgroundDoxorubicin is one of the most effective anti-cancer drugs but its use is limited by cumulative cardiotoxicity that restricts lifetime dose. Redox damage is one of the most accepted mechanisms of toxicity, but not fully substantiated. Moreover doxorubicin is not an efficient redox cycling compound due to its low redox potential. Here we used genomic and chemical systems approaches in vivo to investigate the mechanisms of doxorubicin cardiotoxicity, and specifically test the hypothesis of redox cycling mediated cardiotoxicity.Methodology/Principal FindingsMice were treated with an acute dose of either doxorubicin (DOX) (15 mg/kg) or 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) (25 mg/kg). DMNQ is a more efficient redox cycling agent than DOX but unlike DOX has limited ability to inhibit gene transcription and DNA replication. This allowed specific testing of the redox hypothesis for cardiotoxicity. An acute dose was used to avoid pathophysiological effects in the genomic analysis. However similar data were obtained with a chronic model, but are not specifically presented. All data are deposited in the Gene Expression Omnibus (GEO). Pathway and biochemical analysis of cardiac global gene transcription and mRNA translation data derived at time points from 5 min after an acute exposure in vivo showed a pronounced effect on electron transport chain activity. This led to loss of ATP, increased AMPK expression, mitochondrial genome amplification and activation of caspase 3. No data gathered with either compound indicated general redox damage, though site specific redox damage in mitochondria cannot be entirely discounted.Conclusions/SignificanceThese data indicate the major mechanism of doxorubicin cardiotoxicity is via damage or inhibition of the electron transport chain and not general redox stress. There is a rapid response at transcriptional and translational level of many of the genes coding for proteins of the electron transport chain complexes. Still though ATP loss occurs with activation caspase 3 and these events probably account for the heart damage.

Throughout our lives, epigenetic processes shape our development and enable us to adapt to a constantly changing environment. Identifying and understanding environmentally induced epigenetic change(s) that may lead to adverse outcomes is vital for protecting public health. This review, therefore, examines the present understanding of epigenetic mechanisms involved in the mammalian life cycle, evaluates the current evidence for environmentally induced epigenetic toxicity in human cohorts and rodent models and highlights the research considerations and implications of this emerging knowledge for public health and regulatory toxicology. Many hundreds of studies have investigated such toxicity, yet relatively few have demonstrated a mechanistic association among specific environmental exposures, epigenetic changes and adverse health outcomes in human epidemiological cohorts and/or rodent models. While this small body of evidence is largely composed of exploratory in vivo high-dose range studies, it does set a precedent for the existence of environmentally induced epigenetic toxicity. Consequently, there is worldwide recognition of this phenomenon, and discussion on how to both guide further scientific research towards a greater mechanistic understanding of environmentally induced epigenetic toxicity in humans, and translate relevant research outcomes into appropriate regulatory policies for effective public health protection.

This work was funded in part by miscellaneous educational funds from the University Hospitals of Leicester National Health Services Trust to support the Endocannabinoid Research Laboratory of University of Leicester. The authors declare no competing interests.

No abstract

High anandamide levels and reduced expression of CB1 and FAAH may play a role in ectopic implantation.

The presence of human-made chemical contaminants in the environment has increased rapidly during the past 70 years. Harmful effects of such contaminants were first reported in the late 1950s in wildlife and later in humans. These effects are predominantly induced by endocrine disrupting chemicals (EDCs), chemicals that mimic the actions of endogenous hormones and leave marks at several levels of organization in organisms, from physiological outcomes (phenotypes) to molecular alterations, including epigenetic modifications. Epigenetic mechanisms play pivotal roles in the developmental processes that contribute to determining adult phenotypes, through so-called epigenetic programming. While there is increasing evidence that EDC exposure during sensitive periods of development can perturb epigenetic programming, it is unclear whether these changes are truly predictive of adverse outcomes. Understanding the mechanistic links between EDCinduced epigenetic changes and phenotypic endpoints will be critical for providing improved regulatory tools to better protect the environment and human health from exposure to EDCs.