Estrogen receptor-α (ERα) is a ligand-inducible protein which mediates estrogenic hormones signaling and defines the luminal BC phenotype. Recently, we demonstrated that even in absence of ligands ERα (apoERα) binds chromatin sites where it regulates transcription of several protein-coding and lncRNA genes. Noteworthy, apoERα-regulated lncRNAs marginally overlap estrogen-induced transcripts, thus representing a new signature of luminal BC genes. By the analysis of H3K27ac enrichment in hormone-deprived MCF-7 cells, we defined a set of Super Enhancers (SEs) occupied by apoERα, including one mapped in proximity of the DSCAM-AS1 lncRNA gene. This represents a paradigm of apoERα activity since its expression is largely unaffected by estrogenic treatment, despite the fact that E2 increases ERα binding on DSCAM-AS1 promoter. We validated the enrichment of apoERα, p300, GATA3, FoxM1 and CTCF at both DSCAM-AS1 TSS and at its associated SE by ChIP-qPCR. Furthermore, by analyzing MCF-7 ChIA-PET data and by 3C assays, we confirmed long range chromatin interaction between the SE and the DSCAM-AS1 TSS. Interestingly, CTCF and p300 binding showed an enrichment in hormone-depleted medium and in the presence of ERα, elucidating the dynamics of the estrogen-independent regulation of DSCAM-AS1 expression. The analysis of this lncRNA provides a paradigm of transcriptional regulation of a luminal specific apoERα regulated lncRNA.

Cytokine gene polymorphisms have been found to be associated with a pre-disposition to a variety of diseases, including inflammatory and cancer diseases. The present study evaluated the influence of six cytokine gene polymorphisms on the level of genomic damage observed in peripheral blood lymphocytes from hospital pathologists chronically exposed to low doses of different xenobiotics. Lymphocytes from 50 pathologists and 50 control subjects were recruited and analyzed in Sister Chromatid Exchange (SCE) and Chromosomal Aberrations (CA) assays. The frequencies of six cytokine gene polymorphisms and their relationships with the cytogenetic damage levels were also evaluated. The results indicated that significant differences were found between pathologists and controls in terms of SCE frequency (p < 0.001) and RI values (p < 0.001), as well as in terms of CA and cells with aberrations (p < 0.001). No associations were found between all analyzed cytokine gene polymorphisms and CA frequency in both pathologists and control groups. Vice versa, among pathologists, homozygote individuals for the IL-6 G allele showed a significantly (p = 0.017) lower frequency of SCE with respect to heterozygote subjects. Similarly, for TGFβ1 codon 10 locus, homozygote for T allele and heterozygote TC subjects showed a significantly (p = 0.021) lower frequency of SCE with respect to homozygote CC individuals. Among controls, no significant differences were found in the frequency of SCE between genotypes at all loci. Based on these results, we speculate that high circulating levels of a pro-inflammatory cytokine like IL-6 and lower levels of the immunosuppressant cytokine TGFβ1 could be associated directly with a longer duration and/or greater intensity of inflammatory processes, and indirectly with significantly higher levels of genomic damage.

The SCEs and CAs results are consistent with other published data, placing hospital workers as a category at risk for genotoxic damage caused by chronic exposure to xenobiotics. The higher levels of cytogenetic damage observed among GSTT1 null, XPD 751 and XPC 939 CC homozygote subjects confirm the importance of the genetic polymorphisms analysis associated to genotoxicological studies.

In response to physical exercise and diet, skeletal muscle adapts to energetic demands through large transcriptional changes. This remodelling is associated with changes in skeletal muscle DNA methylation which may participate in the metabolic adaptation to extracellular stimuli. Yet, the mechanisms by which muscle-borne DNA methylation machinery responds to diet and exercise and impacts muscle function are unknown. Here, we investigated the function of de novo DNA methylation in fully differentiated skeletal muscle. We generated muscle-specific DNA methyltransferase 3A (DNMT3A) knockout mice (mD3AKO) and investigated the impact of DNMT3A ablation on skeletal muscle DNA methylation, exercise capacity and energy metabolism. Loss of DNMT3A reduced DNA methylation in skeletal muscle over multiple genomic contexts and altered the transcription of genes known to be influenced by DNA methylation, but did not affect exercise capacity and whole-body energy metabolism compared to wild type mice. Loss of DNMT3A did not alter skeletal muscle mitochondrial function or the transcriptional response to exercise however did influence the expression of genes involved in muscle development. These data suggest that DNMT3A does not have a large role in the function of mature skeletal muscle although a role in muscle development and differentiation is likely.