Cadmium inhibits lysine acetylation and succinylation inducing testicular injury of mouse during development

Dysregulation of protein succinylation and disease development

As a novel post-translational modification of proteins, succinylation is widely present in both prokaryotes and eukaryotes. By regulating protein translocation and activity, particularly involved in regulation of gene expression, succinylation actively participates in diverse biological processes such as cell proliferation, differentiation and metabolism. Dysregulation of succinylation is closely related to many diseases. Consequently, it has increasingly attracted attention from basic and clinical researchers. For a thorough understanding of succinylation dysregulation and its implications for disease development, such as inflammation, tumors, cardiovascular and neurological diseases, this paper provides a comprehensive review of the research progress on abnormal succinylation. This understanding of association of dysregulation of succinylation with pathological processes will provide valuable directions for disease prevention/treatment strategies as well as drug development.

Protein succinylation: regulating metabolism and beyond

Modifications of protein post-translation are critical modulatory processes, which alters target protein biological activity，function and/or location, even involved in pathogenesis of some diseases. So far, there are at least 16 types of post-translation modifications identified, particularly through recent mass spectrometry analysis. Among them, succinylation (Ksuc) on protein lysine residues causes a variety of biological changes. Succinylation of proteins contributes to many cellular processes such as proliferation, growth, differentiation, metabolism and even tumorigenesis. Mechanically, Succinylation leads to conformation alteration of chromatin or remodeling. As a result, transcription/expression of target genes is changed accordingly. Recent research indicated that succinylation mainly contributes to metabolism modulations, from gene expression of metabolic enzymes to their activity modulation. In this review, we will conclude roles of succinylation in metabolic regulation of glucose, fat, amino acids and related metabolic disease launched by aberrant succinylation. Our goal is to stimulate extra attention to these still not well researched perhaps important succinylation modification on proteins and cell processes.

The inter- and multi- generational epigenetic alterations induced by maternal cadmium exposure

Exposure to cadmium during pregnancy, from environmental or lifestyle factors, has been shown to have detrimental fetal and placental developmental effects, along with negatively impacting maternal health during gestation. Additionally, prenatal cadmium exposure places the offspring at risk for developing diseases in infancy, adolescence, and adulthood. Although given much attention, the underlying mechanisms of cadmium-induced teratogenicity and disease development remain largely unknown. Epigenetic changes in DNA, RNA and protein modifications have been observed during cadmium exposure, which implies a scientific premise as a conceivable mode of cadmium toxicity for developmental origins of health and disease (DOHaD). This review aims to examine the literature and provide a comprehensive overview of epigenetic alterations induced by prenatal cadmium exposure, within the developing fetus and placenta, and the continued effects observed in childhood and across generations.

Multi-omics analyses reveal the mechanisms of Arsenic-induced male reproductive toxicity in mice

Arsenic (As), a widespread environmental contaminant, can induce serious male reproductive injury; however, the underlying mechanisms remain unclear. Multi-omics analyses, including transcriptome, proteome, and phosphoproteome could promote our understanding of As-induced male reproductive toxicity. Here, we established the reproductive injured mice model by intraperitoneal injection of NaAsO2 (8 mg/kg body weight), which was validated by reduced reproductive cells, sperm motility, and litter size. The followed multi-omics analyses of mice revealed that As exposure inhibited ATP production by decreasing the expression of proteins HK1, and GAPDHS, and the enzymatic activities of PDH and SDH. The inhibition of mitochondrial activity and increase in HDAC2 and MTA3 dysregulated the lysine acetylation levels of histone and global proteins. Specifically, the downregulated histones H4K5ac and H4K12ac and upregulated histone H3K9ac disordered the distribution of TP1 to interfere with spermatogenesis. Moreover, As could reduce the expression of COL1A1, RAB13, and LSR to disrupt the junctions between seminiferous tubules, and thereinto, the inhibition of RAB13 increased PKA-dependent phosphorylation. Our study reveals that As causes male reproductive toxicity through decreasing energy production, altering histone acetylation, and impairing cell junctions. Our findings provide basic data for further studies on As reproductive toxicity.

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.

Counteracting effects of heavy metals and antioxidants on male fertility

Infertility is regarded as a global health problem affecting 8-12% of couples. Male factors are regarded as the main cause of infertility in 40% of infertile couples and contribute to this condition in combination with female factors in another 20% of cases. Abnormal sperm parameters such as oligospermia, asthenospermia, and teratozoospermia result in male factor infertility. Several studies have shown the deteriorative impact of heavy metals on sperm parameters and fertility in human subjects or animal models. Other studies have pointed to the role of antioxidants in counteracting the detrimental effects of heavy metals. In the currents study, we summarize the main outcomes of studies that assessed the counteracting impacts of heavy metal and antioxidants on male fertility. Based on the provided data from animal studies, it seems rational to administrate appropriate antioxidants in persons who suffer from abnormal sperm parameters and infertility due to exposure to toxic elements. Yet, further human studies are needed to approve the beneficial effects of these antioxidants.

Cadmium mediated redox modulation in germline stem cells homeostasis affects reproductive health of Drosophila males

Maintenance of male germline stem cells (GSCs) homeostasis is crucial for successful reproductive life of adults. New insights gained on dysfunction in stem cell maintenance could be the basis of stem cell dependent ailment during adulthood. Cadmium (Cd), a reported male reproductive toxicant, has been explored inadequately for its impact on male GSCs maintenance. The present study, therefore, has been aimed to evaluate the adverse effect of Cd on the homeostasis of GSCs by using Drosophila testis as an in vivo model. Following developmental exposure of environmentally relevant concentrations of Cd (5.0, 10.0 and 20.0 μg/mL) to Drosophila, we showed that a significantly increased level of reactive oxygen species (ROS) at 20.0 μg/mL of Cd resulted in alteration of GSCs number accompanied by inappropriate differentiation leading to reduced sperm number and eventually poor reproductive performance in exposed organism. Rescuing effect was evident by overexpressing sod in the early germ cell stage. The study suggests that an alteration in GSCs homeostasis due to redox imbalance plays a pivotal role in Cd induced failure in male fertility. The study further advocates for the use of Drosophila as an alternative animal model for in vivo evaluation of male GSCs toxicity with minimal ethical concern.

Comprehensive Review of Cadmium Toxicity Mechanisms in Male Reproduction and Therapeutic Strategies

Cadmium (Cd) has been widely studied as an environmental pollutant for many years. Numerous studies have reported that Cd exposure causes damage to the heart, liver, kidneys, and thyroid in vivo. The emerging evidence suggests that Cd exposure induces damage on male reproductive system, which is related to oxidative stress, inflammation, steroidogenesis disruption, and epigenetics. Current preclinical animal studies have confirmed a large number of proteins and intracellular signaling pathways involved in the pathological process of Cd-induced male reproductive damage and potential measures for prophylaxis and treatment, which primarily include antioxidants, anti-inflammatory agents, and essential ion supplement. However, explicit pathogenesis and effective treatments remain uncertain. This review collects data from the literatures, discusses the underlying mechanisms of Cd-induced toxicity on male reproductive function, and summarizes evidence that may provide guidance for the treatment and prevention of Cd-induced male reproductive toxicity.

Ca2+ ionophore A23187 inhibits ATP generation reducing mouse sperm motility and PKA-dependent phosphorylation

Male infertility is a global problem in modern society of which capacitating defects are a major cause. Previous studies have demonstrated that Ca²⁺ ionophore A23187 can make mouse sperm capable of fertilizing in vitro, which may aid in clinical treatment of capacitating defects. However, the detailed role and mechanism of Ca²⁺ in the capacitating process are still unclear especially how A23187 quickly renders sperm immotile and inhibits cAMP/PKA-mediated phosphorylation. We report that A23187 induces a Ca²⁺ flux in the mitochondria enriched sperm tail and excess Ca²⁺ inhibits key metabolic enzymes involved in acetyl-CoA biosynthesis, TCA cycle and electron transport chain pathways resulting in reduced ATP and overall energy production, however this flux does not destroy the structure of the sperm tail. Due to the decrease in ATP production, which is the main phosphate group donator and the power of sperm, the sperm is rendered immobile and PKA-mediated phosphorylation is inhibited. Our study proposed a possible mechanism through which A23187 reduces sperm motility and PKA-mediated phosphorylation from ATP generation, thus providing basic data for exploring the functional roles of Ca²⁺ in sperm in the future.

Cyanidin-3-O-glucoside restores spermatogenic dysfunction in cadmium-exposed pubertal mice via histone ubiquitination and mitigating oxidative damage

Cadmium (Cd) is an environmental contaminant found in soil, water, and food, and can cause oxidative stress and male reproductive damage. During puberty, the male reproductive system is very vulnerable to interference, however, the dysregulation of Cd on spermatogenesis in this period is ambiguous. The anthocyanin cyanidin-3-O-glucoside (C3G) is phytochemical rich in plants and fruits and has been shown to have remarkable anti-oxidant activity, making it an ideal nutrient for nutritional intervention. By modeling Cd-induced damage in male pubertal mice and feeding with C3G, we demonstrated that the C3G could rescue the amount and activity of sperm predominantly. Furthermore, C3G showed partial resistance to Cd-induced histone modification during spermiogenesis and prevented oxidative damage of the DNA in the sperm nucleus. Additionally, C3G mitigated the oxidative stress of testis to achieve the level coinciding with the control group. Meanwhile, Cd-induced mitochondrial apoptosis of sperm cells was reduced significantly via the MAPK signaling pathway in the presence of C3G. Collectively, our findings can offer a potential intervention for combating Cd-induced reproductive damage during puberty by taking anthocyanin as a dietary supplement.

Lead-mediated inhibition of lysine acetylation and succinylation causes reproductive injury of the mouse testis during development

Lead (Pb), a widespread heavy metal, may induce serious diseases, particularly male reproductive injury. However, the mechanisms by which Pb induces testicular injury remain unclear. In this paper, we established a mouse model of Pb-induced testicular injury via an intraperitoneal injection of lead chloride at a concentration of 1.5 mg/kg body weight. We confirmed that Pb could induce a series of injuries, including a low litter size, smaller testes, more weak offspring, direct injury, and aberrant spermiogenesis. Our study demonstrated that Pb could inhibit lysine acetylation (Kac) and succinylation (Ksuc) via western blot (WB) and immunofluorescence (IF) analyses. We subsequently separated different germ cells that contained Pre-meiotic spermatogonia (SPG), meiotic spermatocyte (SPC), and round spermatid (RS) into the Pb-treated and control groups and verified that Pb inhibited Kac in SPC, RS, and particularly, during meiosis. Furthermore, our results regarding the inhibition of pyruvate kinase and mitochondrial electron transport chain complex I and II in the Pb-treated groups suggested that Pb may restrain key enzymes to block the TCA cycle and that the low TCA cycle activity could reduce the contents of two important metabolites, acetyl-CoA and succinyl-CoA, to inhibit Kac and Ksuc. Moreover, we examined the influences of the inhibition of Kac and Ksuc on spermiogenesis, which indicated that decreased Kac and Ksuc could impede the replacement of transition proteins in elongating sperm and disorder the distribution of germ cells in the seminiferous tubule. Our research provides novel insights into the mechanisms of Pb reproductive toxicity with respect to lysine acetylation and succinylation.

Mechanism of cadmium poisoning on testicular injury in mice

Cadmium is a heavy metal that is toxic to humans and the reproductive system. The present study aimed to investigate the mechanisms of cadmium-induced reproductive toxicity in a male Institute of Cancer Research mouse model of cadmium poisoning. Changes in luteinizing hormone receptor (LHR), 17α-hydroxylase and endothelial nitric oxide (NO) synthase (eNOS) expression levels were examined. A total of 24 male mice (4-week-old) were randomly divided into four groups (normal control group and low, medium and high cadmium groups) and subjected to gavage treatment with normal saline or cadmium-containing saline solutions for 8 weeks prior to sacrifice. To assess testicular injury, serum androgen levels were determined by ELISA, testicular tissue pathological changes were evaluated using hematoxylin and eosin staining. In addition, LHR, 17α-hydroxylase and eNOS expressions levels were examined by western blotting, and apoptosis was examined with a terminal deoxynucleotidyl transferase dUTP nick end labeling assay. The results demonstrated that the severity of testes injury increased with cadmium concentration. In addition, LHR, 17α-hydroxylase and eNOS expression levels increased with low and medium concentrations of cadmium; however, they were decreased following treatment with high concentrations of cadmium. The results from the present study demonstrated that cadmium altered LHR, 17α-hydroxylase and eNOS expression levels in testicular stromal cells, which may impact testosterone synthesis. Furthermore, NO was suggested to be involved in cadmium-induced testicular injury by measurements of eNOS expression in testicular stromal cells.

Cadmium-induced genome-wide DNA methylation changes in growth and oxidative metabolism in Drosophila melanogaster

Background

Cadmium (Cd)-containing chemicals can cause serious damage to biological systems. In animals and plants, Cd exposure can lead to metabolic disorders or death. However, for the most part the effects of Cd on specific biological processes are not known. DNA methylation is an important mechanism for the regulation of gene expression. In this study we examined the effects of Cd exposure on global DNA methylation in a living organism by whole-genome bisulfite sequencing (WGBS) using Drosophila melanogaster as model.

Results

A total of 71 differentially methylated regions and 63 differentially methylated genes (DMGs) were identified by WGBS. A total of 39 genes were demethylated in the Cd treatment group but not in the control group, whereas 24 showed increased methylation in the former relative to the latter. In most cases, demethylation activated gene expression: genes such as Cdc42 and Mekk1 were upregulated as a result of demethylation. There were 37 DMGs that overlapped with differentially expressed genes from the digital expression library including baz, Act5C, and ss, which are associated with development, reproduction, and energy metabolism.

Conclusions

DNA methylation actively regulates the physiological response to heavy metal stress in Drosophila in part via activation of apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5688-z) contains supplementary material, which is available to authorized users.

Puerarin prevents cadmium-induced hepatic cell damage by suppressing apoptosis and restoring autophagic flux

Cadmium (Cd) is a common heavy metal contamination that is highly toxic to liver. Puerarin (PU), a potent free radical scavenger, has been shown to exert cytoprotective effect in numerous pathological processes. However, whether PU affords protection against Cd-induced hepatotoxicity remains unclear to be known. Here, we aimed to investigate the protective effect of PU on Cd-induced hepatotoxicity in an immortalized mouse hepatocyte line, AML-12. First, Cd-induced cytotoxicity in AML-12 cells was obviously ameliorated by PU treatment. Also, Cd-induced apoptotic cell death was markedly alleviated by PU treatment, evidenced by two methods. Simultaneously, Cd-elevated malondialdehyde and reactive oxygen species levels were significantly reduced by PU administration, demonstrating the antioxidant effect of PU against Cd exposure. Moreover, Cd-induced blockage of autophagic flux in AML-12 cells was obviously restored by PU treatment, evidenced by immunoblot analysis of autophagy marker proteins and tandem fluorescent-tagged LC3 method. Resultantly, Cd-induced autophagosome accumulation was significantly alleviated by PU treatment. In conclusion, these observations demonstrate that PU treatment alleviates Cd-induced hepatic cell damage by inhibiting apoptosis and restoring autophagy activity, which is intimately related with its antioxidant activity.

Large-Scale Assessment of Bioinformatics Tools for Lysine Succinylation Sites

Lysine succinylation is a form of posttranslational modification of the proteins that play an essential functional role in every aspect of cell metabolism in both prokaryotes and eukaryotes. Aside from experimental identification of succinylation sites, there has been an intense effort geared towards the development of sequence-based prediction through machine learning, due to its promising and essential properties of being highly accurate, robust and cost-effective. In spite of these advantages, there are several problems that are in need of attention in the design and development of succinylation site predictors. Notwithstanding of many studies on the employment of machine learning approaches, few articles have examined this bioinformatics field in a systematic manner. Thus, we review the advancements regarding the current state-of-the-art prediction models, datasets, and online resources and illustrate the challenges and limitations to present a useful guideline for developing powerful succinylation site prediction tools.