Copper effective binding with 32–62 and 94–125 peptide fragments of histone H2B

Effect of Environmental Stressors, Xenobiotics, and Oxidative Stress on Male Reproductive and Sexual Health

This article examines the environmental factor-induced oxidative stress (OS) and their effects on male reproductive and sexual health. There are several factors that induce OS, i.e. radition, metal contamination, xenobiotic compounds, and cigarette smoke and lead to cause toxicity in the cells through metabolic or bioenergetic processes. These environmental factors may produce free radicals and enhance the reactive oxygen species (ROS). Free radicals are molecules that include oxygen and disbalance the amount of electrons that can create major chemical chains in the body and cause oxidation. Oxidative damage to cells may impair male fertility and lead to abnormal embryonic development. Moreover, it does not only cause a vast number of health issues such as ageing, cancer, atherosclerosis, insulin resistance, diabetes mellitus, cardiovascular diseases, ischemia-reperfusion injury, and neurodegenerative disorders but also decreases the motility of spermatozoa while increasing sperm DNA damage, impairing sperm mitochondrial membrane lipids and protein kinases. This chapter mainly focuses on the environmental stressors with further discussion on the mechanisms causing congenital impairments due to poor sexual health and transmitting altered signal transduction pathways in male gonadal tissues.

Copper affects the binding of HIF-1α to the critical motifs of its target genes

Copper regulates the target gene selection of HIF-1α under hypoxic conditions by affecting HIF-1α-DNA binding patterns across the genome.

Endocytosis of G Protein-Coupled Receptors and Their Ligands: Is There a Role in Metal Trafficking?

The prevalence of metal dysregulation in many neurodegenerative and neurocognitive disorders has compelled many studying such diseases to investigate the mechanisms underlying metal regulation in the central nervous system. Metal homoeostasis is often complex, with sophisticated, multilayered pathways in operation. G protein-coupled receptors are omnipresent on cell membranes and have intriguing mechanisms of endocytosis and trafficking that may be useful in metal homoeostasis. Indeed, many receptors and/or their cognate ligands are able to bind metals, and in many cases metals are considered to have neuromodulatory roles as a result of receptor binding. In this mini-review, we outline the structural and functional aspects of G protein-coupled receptors with a focus on the mechanisms leading to endocytosis and cellular trafficking. We further highlight how this may help in the trafficking of metal ions, notably copper.

Influence of toxicologically relevant metals on human epigenetic regulation

Environmental toxicants such as toxic metals can alter epigenetic regulatory features such as DNA methylation, histone modification, and non-coding RNA expression. Heavy metals influence gene expression by epigenetic mechanisms and by directly binding to various metal response elements in the target gene promoters. Given the role of epigenetic alterations in regulating genes, there is potential for the integration of toxic metal-induced epigenetic alterations as informative factors in the risk assessment process. Here, we focus on recent advances in understanding epigenetic changes, gene expression, and biological effects induced by toxic metals.

Mechanisms of base substitution mutagenesis in cancer genomes

Cancer genome sequence data provide an invaluable resource for inferring the key mechanisms by which mutations arise in cancer cells, favoring their survival, proliferation and invasiveness. Here we examine recent advances in understanding the molecular mechanisms responsible for the predominant type of genetic alteration found in cancer cells, somatic single base substitutions (SBSs). Cytosine methylation, demethylation and deamination, charge transfer reactions in DNA, DNA replication timing, chromatin status and altered DNA proofreading activities are all now known to contribute to the mechanisms leading to base substitution mutagenesis. We review current hypotheses as to the major processes that give rise to SBSs and evaluate their relative relevance in the light of knowledge acquired from cancer genome sequencing projects and the study of base modifications, DNA repair and lesion bypass. Although gene expression data on APOBEC3B enzymes provide support for a role in cancer mutagenesis through U:G mismatch intermediates, the enzyme preference for single-stranded DNA may limit its activity genome-wide. For SBSs at both CG:CG and YC:GR sites, we outline evidence for a prominent role of damage by charge transfer reactions that follow interactions of the DNA with reactive oxygen species (ROS) and other endogenous or exogenous electron-abstracting molecules.

Amino acid-based tweezers: the role of turn-like conformation in the binding of copper(II)

The importance of turn-like peptide conformation for the copper(II) binding has been revealed by the synthesis of simple amino acid-based tweezers and the study of their interaction with copper(II). Amino acids Phe, Leu, Val, Ala and Gly were bridged through their C-terminuses with conformationally constrained motif, cis enediyne moiety ((Z)-octa-4-en-2,6-diyne-1,8-diamine). The interaction of prepared diamine ligands with copper(II) was studied by means of potentiometric titrations, UV-visible and EPR spectroscopic and mass spectrometric techniques. All ligands interact efficiently with copper(II) and form complexes of 1:1 stoichiometry differing in the protonation state of the ligand. LCu(2+) species were found predominant at pH<6.5, with log K* ranging from -8.06 to -6.65, while at higher pH deprotonation occurred, giving rise to LH(-1)Cu(+) complexes or LH(-2)Cu complex for the phenylalanine-related ligand. An additional species, LH(-3)Cu(-) were found at pH>9 for the valine- and alanine-related ligands, respectively. Comparing stability of studied complexes with those reported in previous work revealed that ligands effectively emulate properties of copper(II) binding peptides. Based on the results obtained in this work it can be concluded that structural rigidity significantly enhances coordination properties of the ligand, thus conforming importance of the turn-like peptide conformation for the copper(II) binding.

Copper and the herbicide atrazine impair the stress response of the freshwater fish Prochilodus lineatus

In order to evaluate the effects of copper and atrazine on the stress response of the freshwater fish Prochilodus lineatus, juvenile fish were pre-exposed to copper (20 μg L(-1)) or atrazine (10 μg L(-1)) for 24 h and then submitted to air exposure for 3 min. Simultaneously fish kept in dechlorinated water for 24 h were subjected to air exposure and a non-stress group was not subjected to air stress or any contaminants. Animals were sampled immediately (t0) and after 1, 3 and 6 h of air exposure (t1, t3 and t6 respectively) for the analysis of plasma cortisol, glucose and Na(+), hepatic glycogen, branchial Na(+)/K(+)-ATPase (NKA), number of red blood cells per cubic millimeter of blood (RBC), hematocrit (Hct) and hemoglobin content (Hb). In fish pre-exposed to copper the stress response was inhibited, and at t1 and t3 both cortisol and glucose remained significantly lower compared to fish subjected to air stress only. In fish pre-exposed to atrazine there was no rise in cortisol, but there was an increase in plasma glucose, RBC, Hct and Hb at t0 and a return of these parameters to basal levels at t1, as they did not differ significantly in relation to non-stressed fish. Animals pre-exposed to either Cu or atrazine showed a significant reduction in NKA activity at t1 and t3, in relation to air stressed fish. These results clearly indicate that copper and atrazine impair cortisol stress response of P. lineatus and that fish subjected to a contaminant-induced stress, either by copper or atrazine, may not be able to respond to any additional stressors.

DNA strand breakage induced by CuII and NiII, in the presence of peptide models of histone H2B

In the present study we used the plasmid relaxation assay, a very sensitive method for detection of DNA strand breaks in vitro, in order to evaluate the role of peptide fragments of histone H2B in DNA strand breakage induced by copper and nickel. We have found that in the presence of peptides modeling the histone fold domain (H2B(32-62) and H2B(63-93)) as well as the N-terminal tail (H2B(1-31)) of histone H2B there is an increased DNA damage by Cu(2+)/H(2)O(2) and Ni(2+)/H(2)O(2) reaction mixtures. On the contrary, the C-terminal tail (H2B(94-125)) seems to have a protective role on the attack of ROS species to DNA. We have rendered our findings to the interactions of the peptides with DNA, as well as with the metal.