Metabolism of 1,3-butadiene to toxicologically relevant metabolites in single-exposed mice and rats.

1,3-Butadiene (BD) was carcinogenic in rodents. This effect is related to reactive metabolites such as 1,2-epoxy-3-butene (EB) and especially 1,2:3,4-diepoxybutane (DEB). A third mutagenic epoxide, 3,4-epoxy-1,2-butanediol (EBD), can be formed from DEB and from 3-butene-1,2-diol (B-diol), the hydrolysis product of EB. In BD exposed rodents, only blood concentrations of EB and DEB have been published. Direct determinations of EBD and B-diol in blood are missing. In order to investigate the BD-dependent blood burden by all of these metabolites, we exposed male B6C3F1 mice and male Sprague-Dawley rats in closed chambers over 6–8 h to constant atmospheric BD concentrations. BD and exhaled EB were measured in chamber atmospheres during the BD exposures. EB blood concentrations were obtained as the product of the atmospheric EB concentration at steady state with the EB blood-to-air partition coefficient. B-diol, EBD, and DEB were determined in blood collected immediately at the end of BD exposures up to 1200 ppm (B-diol, EBD) and 1280 ppm (DEB). Analysis of BD was done by GC/FID, of EB, DEB, and B-diol by GC/MS, and of EBD by LC/MS/MS. EB blood concentrations increased with BD concentrations amounting to 2.6 ?mol/l (rat) and 23.5 ?mol/l (mouse) at 2000 ppm BD and to 4.6 ?mol/l in rats exposed to 10000 ppm BD. DEB (detection limit 0.01 ?mol/l) was found only in blood of mice rising to 3.2 ?mol/l at 1280 ppm BD. B-diol and EBD were quantitatively predominant in both species. B-diol increased in both species with the BD exposure concentration reaching 60 ?mol/l at 1200 ppm BD. EBD reached maximum concentrations of 9.5 ?mol/l at 150 ppm BD (rat) and of 42 ?mol/l at 300 ppm BD (mouse). At higher BD concentrations EBD blood concentrations decreased again. This picture probably results from a competitive inhibition of the EBD producing CYP450 by BD, which occurs in both species

Quantitative investigation on the metabolism of 1,3-butadiene and of its oxidized metabolites in once-through perfused livers of mice and rats.

The industrial chemical 1,3-butadiene (BD) is a potent carcinogen in mice and a weak one in rats. This difference is generally related to species-specific burdens by the metabolites 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 3,4-epoxy-1,2-butanediol (EBD), which are all formed in the liver. Only limited data exist on BD metabolism in the rodent liver. Therefore, metabolism of BD, its epoxides, and the intermediate 3-butene-1,2-diol (B-diol) was studied in once-through perfused livers of male B6C3F1 mice and Sprague-Dawley rats. In BD perfusions, predominantly EB and B-diol were found (both species). DEB and EBD were additionally detected in mouse livers. Metabolism of BD showed saturation kinetics (both species). In EB perfusions, B-diol, EBD, and DEB were formed with B-diol being the major metabolite. Net formation of DEB was larger in mouse than in rat livers. In both species, hepatic clearance (Cl(H)) of EB was slightly smaller than the perfusion flow. In DEB perfusions, EBD was formed as a major metabolite. Cl(H) of DEB was 61% (mouse) and 73% (rat) of the perfusion flow. In the B-diol-perfused rat liver, EBD was formed as a minor metabolite. Cl(H) of B-diol was 53% (mouse) and 34% (rat) of the perfusion flow. In EBD-perfused rat livers, Cl(H) of EBD represented only 22% of the perfusion flow. There is evidence for qualitative species differences with regard to the enzymes involved in BD metabolism. The first quantitative findings in whole livers showing intrahepatic first-pass metabolism of BD and EB metabolites will improve the risk estimation of BD

Novel Antioxidants Protect Mitochondria from the Effects of Oligomeric Amyloid Beta and Contribute to the Maintenance of Epigenome Function

Alzheimer’s disease is associated with metabolic deficits and reduced mitochondrial function, with the latter due to the effects of oligomeric amyloid beta peptide (AβO) on the respiratory chain. Recent evidence has demonstrated reduction of epigenetic markers, such as DNA methylation, in Alzheimer’s disease. Here we demonstrate a link between metabolic and epigenetic deficits via reduction of mitochondrial function which alters the expression of mediators of epigenetic modifications. AβO-induced loss of mitochondrial function in differentiated neuronal cells was reversed using two novel antioxidants (<b>1</b> and <b>2</b>); both have been shown to mitigate the effects of reactive oxygen species (ROS), and compound <b>1</b> also restores adenosine triphosphate (ATP) levels. While both compounds were effective in reducing ROS, restoration of ATP levels was associated with a more robust response to AβO treatment. Our in vitro system recapitulates key aspects of data from Alzheimer’s brain samples, the expression of epigenetic genes in which are also shown to be normalized by the novel analogues

Hsp60 Inhibitors and Modulators

In this chapter, we focus on the 60 KDa Heat Shock Protein (Hsp60) and discuss some of its biological, molecular and pathological features. The structural and mechanistic aspect of the Hsp60 folding cycle will be also presented. We further illustrate how Hsp60 may be involved in many diseases and therefore considered as an effective therapeutic or theranostic target. Finally, the state-of-the-art on the development of Hsp60 and bacterial GroEL inhibitors and modulators of their expression will be illustrated. This is discussed in the light of a negative chaperonotherapy, and the consequent development of inhibitors, as well as positive chaperonotherapy, in the event its excessive activity is a disease-contrasting event

Chaperonotherapy for Alzheimer’s Disease: Focusing on HSP60

This review will analyze growing evidence suggesting a convergence between two major areas of research: Alzheimer\u2019s disease (AD) and chaperonopathies. While AD is a widely recognized medical, public health, and social problem, the chaperonopathies have not yet been acknowledged as a related burden of similar magnitude. However, recent evidence collectively indicates that such possibility exists in that AD, or at least some forms of it, may indeed be a chaperonopathy. The importance of considering this possibility cannot be overemphasized since it provides a novel point of view to examine AD and potentially suggests new therapeutic avenues. In this review, we focus on the mitochondrial chaperone HSP60 and discuss some of its biological, molecular, and pathological facets as they pertain to AD. We further illustrate how HSP60 may be an etiologic-pathogenic factor in AD and, as such, it could become a novel, effective therapeutic target. This possibility is discussed both in the light of negative chaperonotherapy, namely the development of means to inhibit HSP60 in the event its excessive activity is a disease-promoting event in AD, as well as positive chaperonotherapy, that is boosting its activity if, on the other hand, it is demonstrated that HSP60 insufficiency is a key feature of AD with such pathological consequences as causing mitochondrial dysfunction

A single-cell atlas of entorhinal cortex from individuals with Alzheimer’s disease reveals cell-type-specific gene expression regulation

There is currently little information available about how individual cell types contribute to Alzheimer’s disease. Here we applied single-nucleus RNA sequencing to entorhinal cortex samples from control and Alzheimer’s disease brains (n = 6 per group), yielding a total of 13,214 high-quality nuclei. We detail cell-type-specific gene expression patterns, unveiling how transcriptional changes in specific cell subpopulations are associated with Alzheimer’s disease. We report that the Alzheimer’s disease risk gene APOE is specifically repressed in Alzheimer’s disease oligodendrocyte progenitor cells and astrocyte subpopulations and upregulated in an Alzheimer’s disease-specific microglial subopulation. Integrating transcription factor regulatory modules with Alzheimer’s disease risk loci revealed drivers of cell-type-specific state transitions towards Alzheimer’s disease. For example, transcription factor EB, a master regulator of lysosomal function, regulates multiple disease genes in a specific Alzheimer’s disease astrocyte subpopulation. These results provide insights into the coordinated control of Alzheimer’s disease risk genes and their cell-type-specific contribution to disease susceptibility. These results are available at http://adsn.ddnetbio.com