DNA hypermethylation of acetoacetyl-CoA synthetase contributes to inhibited cholesterol supply and steroidogenesis in fetal rat adrenals under prenatal nicotine exposure

Meta-analysis of gonadal transcriptome provides novel insights into sex change mechanism across protogynous fishes

Protogyny, being capable of changing from female to male during their lifetime, is prevalent in 20 families of teleosts but is believed to have evolved within specific evolutionary lineages. Therefore, shared regulatory factors governing the sex change process are expected to be conserved across protogynous fishes. However, a comprehensive understanding of this mechanism remains elusive. To identify these factors, we conducted a meta-analysis using gonadal transcriptome data from seven species. We curated data pairs of ovarian tissue and transitional gonad, and employed ratios of expression level as a unified criterion for differential expression, enabling a meta-analysis across species. Our approach revealed that classical sex change-related genes exhibited differential expression levels between the ovary and transitional gonads, consistent with previous reports. These results validate our methodology's robustness. Additionally, we identified novel genes not previously linked to gonadal sex change in fish. Notably, changes in the expression levels of acetoacetyl-CoA synthetase and apolipoprotein Eb, which are involved in cholesterol synthesis and transport, respectively, suggest that the levels of cholesterol, a precursor of steroid hormones crucial for sex change, are decreased upon sex change onset in the gonads. This implies a potential universal influence of cholesterol dynamics on gonadal transformation in protogyny.

Epigenetic and Long-Term Effects of Nicotine on Biology, Behavior, and Health

Tobacco and nicotine use are associated with disease susceptibility and progression. Health challenges associated with nicotine and smoking include developmental delays, addiction, mental health and behavioral changes, lung disease, cardiovascular disease, endocrine disorders, diabetes, immune system changes, and cancer. Increasing evidence suggests that nicotine-associated epigenetic changes may mediate or moderate the development and progression of a myriad of negative health outcomes. In addition, nicotine exposure may confer increased lifelong susceptibility to disease and mental health challenges through alteration of epigenetic signaling. This review examines the relationship between nicotine exposure (and smoking), epigenetic changes, and maladaptive outcomes that include developmental disorders, addiction, mental health challenges, pulmonary disease, cardiovascular disease, endocrine disorders, diabetes, immune system changes, and cancer. Overall, findings support the contention that nicotine (or smoking) associated altered epigenetic signaling is a contributing factor to disease and health challenges.

Epimutational effects of electronic cigarettes

Electronic cigarettes (e-cigarettes), since they do not require tobacco combustion, have traditionally been considered less harmful than conventional cigarettes (c-cigarettes). In recent years, however, researchers have found many toxic compounds in the aerosols of e-cigarettes, and numerous studies have shown that e-cigarettes can adversely affect the human epigenome. In this review, we provide an update on recent findings regarding epigenetic outcomes of e-cigarette aerosols. Moreover, we discussed the effects of several typical e-cigarette ingredients (nicotine, tobacco-specific nitrosamines, volatile organic compounds, carbonyl compounds, and toxic metals) on DNA methylation, histone modifications, and noncoding RNA expression. These epigenetic effects could explain some of the diseases caused by e-cigarettes. It also reminds the public that like c-cigarettes, inhaling e-cigarette aerosols could also be accompanied with potential epigenotoxicity on the human body.

Smoking and DNA methylation: Correlation of methylation with smoking behavior and association with diseases and fetus development following prenatal exposure

Among epigenetic mechanisms, DNA methylation has been widely studied with respect to many environmental factors. Smoking is a common factor which affects both global and gene-specific DNA methylation. It is supported that smoking directly affects DNA methylation, and these effects contribute to the development and progression of various diseases, such as cancer, lung and cardiovascular diseases and male infertility. In addition, prenatal smoking influences the normal development of the fetus via DNA methylation changes. The DNA methylation profile and its smoking-induced alterations helps to distinguish current from former smokers and non-smokers and can be used to predict the risk for the development of a disease. This review summarizes the DNA methylation changes induced by smoking, their correlation with smoking behavior and their association with various diseases and fetus development.

Bisphenol A induced abnormal DNA methylation of ovarian steroidogenic genes in rare minnow Gobiocypris rarus

Bisphenol A (BPA), an ubiquitous environmental endocrine disruptor chemical, disturbs the mRNA expressions of steroidogenic genes and subsequently steroid hormone synthesis in mammals and aquatic species. However, the underlying regulation mechanisms are barely understood, especially in fish. To explore the regulation mechanism, we exposed female rare minnow Gobiocypris rarus (G. rarus) to BPA at a nominal concentration of 15 μg/L for 7 and 14 days in the present study. Results showed significant increase of gonad somatic index (GSI) and serum estradiol (E2) levels in response to BPA at day 14. The 7-day BPA exposure notably repressed the expression of two ovarian steroidogenic genes (star and hsd11b2) and suppressed their capacity of estrogen response elements (ERE) to recruit estrogen receptor (ER), while the 14-day BPA treatment remarkably induced transcript of hsd3b and enhanced the capacity of ERE to recruitment ER in ovaries. Furthermore, the 7-day BPA exposure caused DNA hypermethylation of star (CpGs: -742 bp and -719 bp) and hsd11b2 (CpG: -1788 bp). However, 14-day BPA exposure resulted in DNA hypomethylation of hsd3b (CpG: -181 bp). Correlation analysis revealed that the DNA methylation levels at specific CpGs in star, hsd3b and hsd11b2 were significantly correlated to their mRNA levels and ER-EREs interactions. These findings suggest that the disturbed steroidogenesis and the transcripts of ovarian steroidogenic genes might attribute to the altered DNA methylation status of these ovarian steroidogenic genes in response to BPA.

α7 nAChR mediated Fas demethylation contributes to prenatal nicotine exposure-induced programmed thymocyte apoptosis in mice

This study aimed to investigate the effects of prenatal nicotine exposure (PNE) on thymocyte apoptosis and postnatal immune impairments in vivo and further explore the epigenetic mechanisms of the pro-apoptotic effect of nicotine in vitro. The results showed that PNE caused immune impairments in offspring on postnatal day 49, manifested as increased IL-4 production and an increased IgG1/IgG2a ratio in serum. Enhanced apoptosis of total and CD4+SP thymocytes was observed both in fetus and in offspring. Further, by exposing thymocytes to 0–100 μM of nicotine in vitro for 48 h, we found that nicotine increased α7 nicotinic acetylcholine receptor (nAChR) expression, activated the Fas apoptotic pathway, and promoted thymocyte apoptosis in concentration-dependent manners. In addition, nicotine could induce Tet methylcytosine dioxygenase (TET) 2 expression and Fas promoter demethylation, which can be abolished by TET2 siRNA transfection. Moreover, the α7 nAChR specific antagonist α-bungarotoxin can abrogate nicotine-induced TET2 increase, and the following Fas demethylation and Fas-mediated apoptosis. In conclusion, our findings showed, for the first time, that α7 nAChR activation could induce TET2-mediated Fas demethylation in thymocytes and results in the upregulation of Fas apoptotic pathway, which provide evidence for elucidating the PNE-induced programmed thymocyte apoptosis.

Nicotine-induced protein expression profiling reveals mutually altered proteins across four human cell lines

Mass spectrometry-based proteomic strategies can profile the expression level of proteins in response to external stimuli. Nicotine affects diverse cellular pathways, however, the nicotine-induced alterations on the global proteome across human cell lines have not been fully elucidated. We measured perturbations in protein levels resulting from nicotine treatment in four cell lines-HEK, HeLa, PaSC, and SH-SY5Y-in a single experiment using tandem mass tags (TMT10-plex) and high-resolution mass spectrometry. We quantified 8590 proteins across all cell lines. Of these, nicotine increased the abundance of 31 proteins 1.5-fold or greater in all cell lines. Likewise, considering proteins with altered levels in at least three of the four cell lines, 64 were up-regulated, while one was down-regulated. Gene ontology analysis revealed that ∼40% of these proteins were membrane bound, and functioned in transmembrane signaling and receptor activity. We highlighted proteins, including APP, APLP2, LAPTM4B, and NCOA4, which were dysregulated by nicotine in all cell lines investigated and may have implications in downstream signaling pathways, particularly autophagy. Using the outlined methodology, studies in additional (including primary) cell lines will provide further evidence that alterations in the levels of these proteins are indeed a general response to nicotine and thereby merit further investigation.