Bisphenol A exposure induces testicular oxidative damage via FTO/m6A/Nrf2 axis during postnatal development in mice

Zinc Attenuates Bisphenol A-Induced Reproductive Toxicity in Male Mice by Inhibiting Ferroptosis and Apoptosis Through Improving Zinc Homeostasis

Bisphenol A (BPA) is a contaminant widely found in food packaging that can reduce sperm quality and impair male fertility. Zinc (Zn) is an important antioxidant involved in many important biological functions. The aim of this study was to explore the protective effect and mechanism of Zn on reproductive toxicity induced by BPA. Male ICR mice were divided into a control group, a BPA group and a BPA + Zn group. The results showed that the body weight, sperm count and sperm motility of the animals in the BPA group were significantly reduced, and testicular structure was damaged. BPA decreased the levels of serum total Zn, testis-free zinc, ADH and ALP, upregulated the expression of ZnT4 protein, and down-regulated the expression levels of ZIP8, ZIP14, ZnT1, MT and MTF1 protein, resulting in the imbalance of testicular Zn homeostasis. BPA down-regulates the antioxidant enzymes SOD and GSH-Px, and increases MDA, leading to oxidative stress. BPA up-regulates TF, TFR and STEAP3 and down-regulates SLC7A11, GPX4, FPN1 and FTH protein levels, resulting in abnormal iron metabolism and ferroptosis. BPA down-regulated anti-apoptotic protein Bcl-2, up-regulated pro-apoptotic markers Bax, caspase-9, caspase-8 and caspase-3, and induced apoptosis. BPA also increased the phosphorylation of JNK and ERK1/2, but did not increase the phosphorylation of P38. Zn significantly increased body weight and sperm quality, improved testicular morphology, down-regulated p-JNK/JNK and p-ERK/ERK levels, improved oxidative stress, and reduced ferroptosis and apoptosis. In conclusion, Zn regulates Zn homeostasis and down-regulates the MAPK signaling pathway, thereby inhibiting ferroptosis and apoptosis, alleviating BPA-induced oxidative stress and ultimately improving male reproductive damage.

Alterations Expression of Key RNA Methylation (m6A) Enzymes in Testicular Tissue of Rats with Induced Varicocele

Epigenetics impacts male fertility and reproductive disorders. RNA modifications, like m6A, influence RNA metabolism. Varicocele contributes to male infertility, and oxidative stress affects sperm function. This study investigates the expression of key RNA modification enzymes in a rat varicocele model, aiming to elucidate the relationship between varicocele, oxidative stress, and fertility. Fifteen male Wistar rats were divided into Control, Sham, and Varicocele induction groups. Varicocele was induced in the rats surgically. After 8 weeks, testicular tissues and sperm were collected for analysis, including histopathological assessment and evaluation of sperm parameters, functional tests, and gene expression of key RNA modification enzymes: METTL3 as a writer, ALKBH5 and FTO as erasers, and YTHDF2 as a reader involved in recognizing m6A-modified RNA using qRT-PCR. One-way ANOVA with post-hoc Tukey HSD was used for comparing tests within groups. Varicocele induction resulted in histological changes in testicular tissues, including irregularly variable-sized seminiferous tubules. Sperm parameters were significantly affected, with lower concentration, motility, and higher percentage of abnormal sperm in the varicocele group. Increased levels of oxidative stress markers (Sperm lipid peroxidation, and intracytoplasmic ROS) and sperm DNA damage were observed, indicating the presence of oxidative stress in varicocele. Moreover, the expression of key enzymes involved in RNA metabolism was downregulated in the varicocele group. These findings highlight the detrimental impact of varicocele on testicular health, sperm quality, and gene expression, providing insights into the underlying mechanisms of male infertility associated with varicocele.

SUMOylation modification of FTO facilitates oxidative damage response of arsenic by IGF2BP3 in an m6A-dependent manner

N6-methyladenosine (m6A) is the most common form of internal post-transcriptional methylation observed in eukaryotic mRNAs. The abnormally increased level of m6A within the cells can be catalyzed by specific demethylase fat mass and obesity-associated protein (FTO) and stay in a dynamic and reversible state. However, whether and how FTO regulates oxidative damage via m6A modification remain largely unclear. Herein, by using both in vitro and in vivo models of oxidative damage induced by arsenic, we demonstrated for the first time that exposure to arsenic caused a significant increase in SUMOylation of FTO protein, and FTO SUMOylation at lysine (K)- 216 site promoted the down-regulation of FTO expression in arsenic target organ lung, and therefore, remarkably elevating the oxidative damage via an m6A-dependent pathway by its specific m6A reader insulin-like growth factor-2 mRNA-binding protein-3 (IGF2BP3). Consequently, these findings not only reveal a novel mechanism underlying FTO-mediated oxidative damage from the perspective of m6A, but also imply that regulation of FTO SUMOylation may serve as potential approach for treatment of oxidative damage.

Regulatory role of m6A epitranscriptomic modifications in normal development and congenital malformations during embryogenesis

The discovery of N6-methyladenosine (m6A) methylation and its role in translation has led to the emergence of a new field of research. Despite accumulating evidence suggesting that m6A methylation is essential for the pathogenesis of cancers and aging diseases by influencing RNA stability, localization, transformation, and translation efficiency, its role in normal and abnormal embryonic development remains unclear. An increasing number of studies are addressing the development of the nervous and gonadal systems during embryonic development, but only few are assessing that of the immune, hematopoietic, urinary, and respiratory systems. Additionally, these studies are limited by the requirement for reliable embryonic animal models and the difficulty in collecting tissue samples of fetuses during development. Multiple studies on the function of m6A methylation have used suitable cell lines to mimic the complex biological processes of fetal development or the early postnatal phase; hence, the research is still in the primary stage. Herein, we discuss current advances in the extensive biological functions of m6A methylation in the development and maldevelopment of embryos/fetuses and conclude that m6A modification occurs extensively during fetal development. Aberrant expression of m6A regulators is probably correlated with single or multiple defects in organogenesis during the intrauterine life. This comprehensive review will enhance our understanding of the pivotal role of m6A modifications involved in fetal development and examine future research directions in embryogenesis.

Adverse effects of bisphenol A and its analogues on male fertility: An epigenetic perspective

In recent years, there has been growing concern about the adverse effects of endocrine disrupting chemicals (EDCs) on male fertility. Epigenetic modification is critical for male germline development, and has been suggested as a potential mechanism for impaired fertility induced by EDCs. Bisphenol A (BPA) has been recognized as a typical EDC. BPA and its analogues, which are still widely used in various consumer products, have garnered increasing attention due to their reproductive toxicity and the potential to induce epigenetic alteration. This literature review provides an overview of studies investigating the adverse effects of bisphenol exposures on epigenetic modifications and male fertility. Existing studies provide evidence that exposure to bisphenols can lead to adverse effects on male fertility, including declined semen quality, altered reproductive hormone levels, and adverse reproductive outcomes. Epigenetic patterns, including DNA methylation, histone modification, and non-coding RNA expression, can be altered by bisphenol exposures. Transgenerational effects, which influence the fertility and epigenetic patterns of unexposed generations, have also been identified. However, the magnitude and direction of certain outcomes varied across different studies. Investigations into the dynamics of histopathological and epigenetic alterations associated with bisphenol exposures during developmental stages can enhance the understanding of the epigenetic effects of bisphenols, the implication of epigenetic alteration on male fertility, and the health of successive generation.

Dietary selenomethionine reduced oxidative stress by resisting METTL3-mediated m6A methylation level of Nrf2 to ameliorate LPS-induced liver necroptosis in laying hens

Selenomethionine (SeMet) as the main form of daily dietary selenium, occupies essential roles in providing antioxidant and anti-inflammatory properties, which alleviates inflammatory liver damage. N6-methyladenosine (m6A) is one of the most prevalent and abundant internal transcriptional modifications that regulate gene expression. To investigate the protective mechanism of SeMet on liver injury and the regulatory effect of m6A methylation modification, we established the model by supplementing dietary SeMet, and LPS as stimulus in laying hens. LMH cells were intervened with SeMet (0.075 µM) and/or LPS (60 µg/mL). Subsequently, histopathology and ultrastructure of liver were observed. Western Blot, qRT-PCR, colorimetry, MeRIP-qPCR, fluorescent probe staining and AO/EB were used to detect total m6A methylation level, m6A methylation level of Nrf2, ROS, inflammatory and necroptosis factors. Studies showed that SeMet suppressed LPS-induced upregulation of total m6A methylation levels and METTL3 expression. Interestingly, SeMet reduced the m6A methylation level of Nrf2, activated antioxidant pathways and alleviated oxidative stress. LMH cells were transfected with 50 µm siMETTL3. SeMet/SiMETTL3 reversed the LPS-induced reduction in Nrf2 mRNA stability, slowed down its degradation rate. Moreover, LPS induced oxidative stress, led to necroptosis and activated NF-κB to promote the expression of inflammatory factors. SeMet/SiMETTL3 alleviated LPS-induced necroptosis and inflammation. Altogether, SeMet enhanced antioxidant and anti-inflammatory capacity by reducing METTL3-mediated m6A methylation levels of Nrf2, ultimately alleviating liver damage. Our findings provided new insights and therapeutic target for the practical application of dietary SeMet in the treatment and prevention of liver inflammation, and supplied a reference for comparative medicine.