Melatonin protects mouse spermatogonial stem cells against hexavalent chromium-induced apoptosis and epigenetic histone modification

Therapeutic Potential of Aloe vera and Aloe vera-Conjugated Silver Nanoparticles on Mice Exposed to Hexavalent Chromium

Hexavalent chromium (Cr (VI)) is a hazardous heavy metal that induces hepatotoxicity and nephrotoxicity. Thus, this study was planned to explore the ameliorating capacity of Aloe vera leaf gel extract (AV) and their conjugated silver nanoparticles (AVNP) against Cr (VI) induced hepatotoxicity and renal toxicity. The organ indices, level of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, malondialdehyde, total protein, and creatinine in blood serum were measured. The histopathological and micrometric analysis of the hepatic and renal tissue sections were studied. The hepatosomatic index was raised significantly (0.098 ± 0.13 g) in Cr treated group. The blood serum level of AST (484 ± 10.7 U/L), ALT (163 ± 5.5 U/L), ALP (336.7 ± 9.5 U/L), MDA (642.3 ± 28.3 U/L), and creatinine (4.0 ± 0.1 mg/dL) were increased significantly, whereas total protein level was declined (2.8 ± 0.3 g/dL) significantly in Cr exposed group. In the histopathological study, necrosis, disturbed hepatic cords, impaired glomeruli, and Bowman's capsule were noted. Micrometric data from the liver and kidney revealed a significant surge in the size of hepatocytes and their nuclei (1188.2 ± 467.7 µ2 and 456.5 ± 205.6 µ2) and CSA of glomeruli and Bowman's capsule (9051.8 ± 249.8 µ2 and 11,835.5 ± 336.7 µ2) in Cr (VI) exposed group, whereas the brush border (10.2 ± 4.0 µ) size declined significantly. The administration of AV and AVNP reduced the oxidative stress induced by Cr (VI).

Cr (VI)-induced ribosomal DNA copy number variation is associated with semen quality impairment: Evidence from human to animal study

OBJECTIVES

This study aimed to analyze the possible role of rDNA copy number variation in the association between hexavalent chromium [Cr (VI)] exposure and semen quality in semen donors and further confirm this association in mice.

METHODS

In this cross-sectional study, whole blood and semen samples were collected from 155 semen donors in the Zhejiang Human Sperm Bank from January 1st to April 31st, 2021. Adult C57BL/6 J male mice were treated with different doses of Cr (VI) (0, 10, or 15 mg/kg b.w./day). Semen quality, including semen volume, total spermatozoa count, sperm concentration, progressive motility, and total motility, were analyzed according to the WHO laboratory manual. Cr concentration was detected using inductively coupled plasma mass spectrometry. The rDNA copy number was measured using qPCR.

RESULTS

In semen donors, whole blood Cr concentration was negatively associated with semen concentration and total sperm counts. Semen 5 S and 45 S rDNA copy numbers were negatively associated with whole blood Cr concentration and whole blood 5.8 S rDNA copy number was negatively associated with semen Cr concentration. In mice, Cr (VI) damaged testicular tissue, decreased semen quality, and caused rDNA copy number variation. Semen quality was related to the rDNA copy number in whole blood, testicular tissue, and semen samples in mice.

CONCLUSION

Cr (VI) was associated with decreased semen quality in semen donors and mice. Our findings suggest an in-depth analysis of the role of the rDNA copy number variation in the Cr (VI)-induced impairment of semen quality.

H3K9me3 Levels Affect the Proliferation of Bovine Spermatogonial Stem Cells

Spermatogonial stem cells (SSCs) possess the characteristics of self-renewal and differentiation, as well as the ability to generate functional sperm. Their unique stemness has broad applications in male infertility treatment and species preservation. In rodents, research on SSCs has been widely reported, but progress is slow in large livestock such as cattle and pigs due to long growth cycles, difficult proliferation in vitro, and significant species differences. Previously, we showed that histone 3 (H3) lysine 9 (K9) trimethylation (H3K9me3) is associated with the proliferation of bovine SSCs. Here, we isolated and purified SSCs from calf testicular tissues and investigated the impact of different H3K9me3 levels on the in vitro proliferation of bovine SSCs. The enriched SSCs eventually formed classical stem cell clones in vitro in our feeder-free culture system. These clones expressed glial cell-derived neurotrophic factor family receptor alpha-1 (GFRα1, specific marker for SSCs), NANOG (pluripotency protein), C-KIT (germ cell marker), and strong alkaline phosphatase (AKP) positivity. qRT-PCR analysis further showed that these clones expressed the pluripotency genes NANOG and SOX2, and the SSC-specific marker gene GFRα1. To investigate the dynamic relationship between H3K9me3 levels and SSC proliferation, H3K9me3 levels in bovine SSCs were first downregulated using the methyltransferase inhibitor, chaetocin, or transfection with the siRNA of H3K9 methyltransferase suppressor of variegation 3-9 homologue 1 (SUV39H1). The EDU (5-Ethynyl-2'-deoxyuridine) assay revealed that SSC proliferation was inhibited. Conversely, when H3K9me3 levels in bovine SSCs were upregulated by transfecting lysine demethylase 4D (KDM4D) siRNA, the EDU assay showed a promotion of cell proliferation. In summary, this study established a feeder-free culture system to obtain bovine SSCs and explored its effects on the proliferation of bovine SSCs by regulating H3K9me3 levels, laying the foundation for elucidating the regulatory mechanism underlying histone methylation modification in the proliferation of bovine SSCs.

Anti-Oxidative and Anti-Apoptotic Oligosaccharides from Pichia pastoris-Fermented Cress Polysaccharides Ameliorate Chromium-Induced Liver Toxicity

Oxidative stress impairs the structure and function of the cell, leading to serious chronic diseases. Antioxidant-based therapeutic and nutritional interventions are usually employed for combating oxidative stress-related disorders, including apoptosis. Here, we investigated the hepatoprotective effect of oligosaccharides, produced through Pichia pastoris-mediated fermentation of water-soluble polysaccharides isolated from Lepidium sativum (cress) seed mucilage, on chromium(VI)-induced oxidative stress and apoptosis in mice. Gel permeation chromatography (GPC), using Bio-Gel P-10 column, of the oligosaccharides product of fermentation revealed that P. pastoris effectively fermented polysaccharides as no long chain polysaccharides were observed. At 200 µg/mL, fractions DF73, DF53, DF72, and DF62 exhibited DPPH radical scavenging activity of 92.22 ± 2.69%, 90.35 ± 0.43%, 88.83 ± 3.36%, and 88.83 ± 3.36%, respectively. The antioxidant potential of the fermentation product was further confirmed through in vitro H2O2 radical scavenging assay. Among the screened samples, the highest H2O2 radical scavenging activity was displayed by DF73, which stabilized the free radicals by 88.83 ± 0.38%, followed by DF53 (86.48 ± 0.83%), DF62 (85.21 ± 6.66%), DF72 (79.9 4± 1.21%), and EPP (77.76 ± 0.53%). The oligosaccharide treatment significantly alleviated chromium-induced liver damage, as evident from the increase in weight gain, improved liver functions, and reduced histopathological alterations in the albino mice. A distinctly increased level of lipid peroxide (LPO) free radicals along with the endogenous hepatic enzymes were evident in chromium induced hepatotoxicity in mice. However, oligosaccharides treatment mitigated these effects by reducing the LPO production and increasing ALT, ALP, and AST levels, probably due to relieving the oxidative stress. DNA fragmentation assays illustrated that Cr(VI) exposure induced massive apoptosis in liver by damaging the DNA which was then remediated by oligosaccharides supplementation. Histopathological observations confirmed that the oligosaccharide treatment reverses the architectural changes in liver induced by chromium. These results suggest that oligosaccharides obtained from cress seed mucilage polysaccharides through P. pastoris fermentation ameliorate the oxidative stress and apoptosis and act as hepatoprotective agent against chromium-induced liver injury.

The effect of biological mechanisms of melatonin on the proliferation of spermatogonial stem cells: a systematic review

In the last decade, melatonin has gained recognition as a potent scavenger and an effective antioxidant capable of neutralizing free radicals, including reactive oxygen species. Additionally, it exhibits anti-apoptotic properties. In this review, we will examine a compilation of articles that explore the cellular signaling function of melatonin on spermatogonial stem cells (SSCs) and adjacent cells such as Sertoli and Leydig cells. These cells play a crucial role in the proliferation of SSCs both in vitro and in vivo. In this review, we analyze the function of melatonin in the proliferation of SSCs from other aspects. For this purpose, we examine the articles based on the presence of melatonin on SSCs in four groups: As a supplement in SSCs medium culture, SSCs three-dimensional culture system, SSCs freezing medium, and as a therapeutic factor in vivo. Mechanisms of growth and proliferation of SSCs were considered. The purpose of this study is to investigate the potential effects of melatonin as a powerful antioxidant or growth stimulant for SSCs, both in vivo and in vitro.

Supplementing Boar Diet with Nicotinamide Mononucleotide Improves Sperm Quality Probably through the Activation of the SIRT3 Signaling Pathway

Sperm quality is an important indicator to evaluate the reproduction ability of animals. Nicotinamide mononucleotide (NMN) participates in cell energy metabolism and reduces cell oxidative stress. However, the effect and regulatory mechanism of NMN on porcine sperm quality are still unknown. Here, 32 Landrace boars were randomly assigned to four groups (n = 8) and fed with different levels of NMN (0, 8, 16 or 32 mg/kg/d) for 9 weeks, and then serum and semen samples of the boars were collected to investigate the function and molecular mechanism of NMN in sperm quality. The results showed that the dietary NMN supplementation significantly increased sperm volume, density and motility (p < 0.05). Interestingly, NMN apparently improved the antioxidative indexes and increased the levels of testosterone (p < 0.05) in serum. Furthermore, NMN upregulated the protein levels of sirtuin 3 (SIRT3), antioxidation and oxidative phosphorylation (OXPHOS), but downregulated the protein levels of apoptosis in semen. Mechanically, NMN protected sperm from H2O2-induced oxidative stress and apoptosis through SIRT3 deacetylation. Importantly, the SIRT3-specific inhibitor 3-TYP attenuated the antioxidation and antiapoptosis of NMN in sperm. Therefore, NMN exerts antioxidation and antiapoptosis to improve boar sperm quality via the SIRT3 signaling pathway. Our findings suggest that NMN is a novel potential boar antioxidative feed additive to produce high-quality porcine semen.

Effects of hexavalent chromium on mitochondria and their implications in carcinogenesis

Hexavalent chromium (Cr(VI)) is a well-known occupational and environmental human carcinogen. The cellular effect of Cr(VI) is complex and often nonspecific due to its ability to modulate multiple cellular targets. The toxicity of Cr(VI) is strongly linked to the generation of reactive oxygen species (ROS) during its reduction process. ROS can cause oxidation of cellular macromolecules, such as proteins, lipids, and DNA, thereby altering their functions. A major genotoxic effect of Cr(VI) that contributes to carcinogenesis is the formation of DNA adducts, which can lead to DNA damage. Modulations of cellular signaling pathways and epigenetics may also contribute to the carcinogenic effects of Cr(VI). Cr(VI) has a major impact on many aspects of mitochondrial biology, including oxidative phosphorylation, mitophagy, and mitochondrial biogenesis. These effects have the potential to alter the trajectory of Cr(VI)-induced carcinogenic process. This perspective article summarizes current understandings of the effect of Cr(VI) on mitochondria and discusses the future directions of research in this area, particularly with regard to carcinogenesis.

Alteration of epigenetic methyl and acetyl marks by postnatal chromium(VI) exposure causes apoptotic changes in the ovary of the F1 offspring

Hexavalent chromium, Cr(VI), is a heavy metal endocrine disruptor used widely in various industries worldwide and is considered a reproductive toxicant. Our previous studies demonstrated that lactational exposure to Cr(VI) caused follicular atresia, disrupted steroid hormone biosynthesis and signaling, and delayed puberty. However, the underlying mechanism was unknown. The current study investigated the effects of Cr(VI) exposure (25 ppm) during postnatal days 1-21 via dam's milk on epigenetic alterations in the ovary of F1 offspring. Data indicated that Cr(VI) disrupted follicle development and caused apoptosis by increasing DNMT3a /3b and histone methyl marks (H3K27me3 and H3K9me3) along with decreasing histone acetylation marks (H3K9ac and H3K27ac). Our study demonstrates that exposure to Cr(VI) causes changes in the epigenetic marks, partially contributing to the transcriptional repression of genes regulating ovarian development, cell proliferation (PCNA), cell survival (BCL-XL and BCL-2), and activation of genes regulating apoptosis (AIF and cleaved caspase-3), resulting in follicular atresia. The current study suggests a role for epigenetics in Cr(VI)-induced ovotoxicity and infertility.

YTHDF2 controls hexavalent chromium-induced mitophagy through modulating Hif1α and Bnip3 decay via the m6A/mRNA pathway in spermatogonial stem cells/progenitors

Spermatogonial stem cells (SSCs) are the basis of spermatogenesis, and SSC homeostasis is essential for lifelong male fertility. Currently, environmental pollution remains one of the factors affecting human reproductive health. Chromium is a prevalent metal element, and excessive exposure to hexavalent chromium (Cr (VI)) can cause male reproductive disorders. Nevertheless, the toxic effects of Cr (VI) on SSCs and the underlying mechanisms remain incompletely understood. Here, we showed that Cr (VI) exposure triggered mitophagy in mouse SSCs/progenitors in a time-dependent manner. Concurrently, Cr (VI) treatment caused reactive oxygen species (ROS) accumulation and activated the HIF1α-mediated BNIP3 expression to trigger mitophagy. In addition, Cr (VI) exposure significantly decreased the level of m⁶A modification. Further, we identified that YTHDF2 regulated the stability of Bnip3 and Hif1α mRNAs in an m⁶A-dependent manner, which was involved in Cr (VI)-induced mitophagy. Collectively, our study not only expands the mechanisms for Cr (VI)-caused male reproductive toxicity, but also provides pharmacological targets for prevention and treatment of Cr (VI)-induced male fertility impairment.

Pharmacological intervention of biosynthesized Nigella sativa silver nanoparticles against hexavalent chromium induced toxicity in male albino mice

Hexavalent chromium, toxic heavy metal, among the top-rated environmental contaminants, is declared a potent endocrine disruptor in humans and animals. The present study was planned to find harmful effects on the reproductive system caused by Cr (VI) and the ameliorative effect of Nigella sativa and Nigella sativa-mediated AgNP on male mice (Mus musculus). In the present study, known infertility medicine, clomiphene citrate is also used as a positive control. The main objective of the present study was to assess the ameliorative potential of oral administration of a dose of 50 mg/kg BW clomiphene citrate (control), AgNP via chemical synthesis, Nigella sativa seed extract, and Nigella sativa-mediated AgNP against the Cr (VI) at the dose of 1.5 mg/kg BW from K₂Cr₂O₇ orally induced toxicity over eight weeks on the reproductive performance of male albino mice. Nigella sativa mediated AgNPs were characterized by UV, SEM, FTIR, and XRD. The histological analysis, smear study, antioxidant capacity test, and hormone analysis were conducted by blood samples of albino mice. Cr exposed groups showed a significant decrease in sperm head breadth (5.29 ± 0.54 µ) and length (19.54 ± 1.18 µ), middle piece length, tail length, LH (1.65 ± 0.15 ng/mL), testosterone (2.63 ± 0.29 ng/mL), SOD (61.40 ± 2.48 mmol/mL), CAT (87.40 ± 6.01 mmol/mL), GSH (1.54 ± 0.09 µmol/mL), and no of spermatogonia (1.22 ± 0.25), and spermatocytes (2.33 ± 0.943). However, FSH level (160.00 ± 4.98 ng/mL), seminiferous tubule CSA (1094.69 ± 49.76 mm²), size of spermatogonia (41.30 ± 1.24 µ), and spermatocytes (26.07 ± 1.34 µ) were significantly increased. Administration of Nigella sativa and Nigella sativa-mediated AgNPs reduced the toxicity.

Toxic and carcinogenic effects of hexavalent chromium in mammalian cells in vivo and in vitro: a recent update

Chromium VI (Cr (VI)) can cross cell membranes readily and causes the formation of Cr-DNA adducts, genomic damages, elevation of reactive oxygen species (ROS) and alteration of survival signaling pathways, as evidenced by the modulation in p53 signaling pathway. Mammals, including humans are exposed to Cr, including Cr (VI), frequently through inhalation, drinking water, and food. Several studies demonstrated that Cr (VI) induces cellular death through apoptosis and autophagy, genotoxicity, functional alteration of mitochondria, endocrine and reproductive impairments. In the present review, studies on deleterious effects of Cr (VI) exposure to mammalian cells (in vivo and in vitro) have been documented. Special attention is paid to the underlying molecular mechanism of Cr (VI) toxicity.

Protective effects of melatonin against the toxic effects of environmental pollutants and heavy metals on testicular tissue: A systematic review and meta-analysis of animal studies

BACKGROUND

Environmental pollution and infertility are two modern global challenges that agonize personal and public health. The causal relationship between these two deserves scientific efforts to intervene. It is believed that melatonin maintains antioxidant properties and may be utilized to protect the testicular tissue from oxidant effects caused by toxic materials.

METHODS

A systematic literature search was conducted in PubMed, Scopus, and Web of Science to identify the animal trial studies that evaluated melatonin therapy's effects on rodents' testicular tissue against oxidative stress caused by heavy metal and non-heavy metal environmental pollutants. Data were pooled, and standardized mean difference and 95% confidence intervals were estimated using the random-effect model. Also, the risk of bias was assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) tool. (PROSPERO: CRD42022369872).

RESULTS

Out of 10039 records, 38 studies were eligible for the review, of which 31 were included in the meta-analysis. Most of them showed beneficial effects of melatonin therapy on testicular tissue histopathology. [20 toxic materials were evaluated in this review, including arsenic, lead, hexavalent chromium, cadmium, potassium dichromate, sodium fluoride, cigarette smoke, formaldehyde, carbon tetrachloride (CCl4), 2-Bromopropane, bisphenol A, thioacetamide, bisphenol S, ochratoxin A, nicotine, diazinon, Bis(2-ethylhexyl) phthalate (DEHP), Chlorpyrifos (CPF), nonylphenol, and acetamiprid.] The pooled results showed that melatonin therapy increased sperm count, motility, viability and body and testicular weights, germinal epithelial height, Johnsen's biopsy score, epididymis weight, seminiferous tubular diameter, serum testosterone, and luteinizing hormone levels, testicular tissue Malondialdehyde, glutathione peroxidase, superoxide dismutase, and glutathione levels. On the other hand, abnormal sperm morphology, apoptotic index, and testicular tissue nitric oxide were lower in the melatonin therapy arms. The included studies presented a high risk of bias in most SYRCLE domains.

CONCLUSION

In conclusion, our study demonstrated amelioration of testicular histopathological characteristics, reproductive hormonal panel, and tissue markers of oxidative stress. Melatonin deserves scientific attention as a potential therapeutic agent for male infertility.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022369872.

A comprehensive review on human health effects of chromium: insights on induced toxicity

The growing use of heavy metals in most industrial activities has led to it being considered as the most important environmental pollutant that may cause harm and toxicity to animals and humans. Chromium has been found in the environment in different oxidation states such as Cr⁰, Cr(III), and Cr(VI) and is released from a variety of anthropogenic and natural activities. At among, trivalent and hexavalent chromium are the most stable forms. Considerably, Cr(VI) is frequently more toxic than Cr(III) because of its particular solubility and high mobility. Chronic exposure and bioaccumulation of chromium, as a heavy metal, can cause toxicity and numerous pathophysiological defects, including allergic reactions, anemia, burns, and sores especially in the stomach and small intestine, damage to sperm along with the male reproductive system, and affect various biological systems. Chromium pollution can have severe consequences for water and the soil environment. This article reviews the toxicological effects of Cr(VI) and Cr(III) and their mechanisms of toxicity and carcinogenicity.

Overview of biological effects of melatonin on testis: A review

Infertility is a major global health issue and male factors account for half of all infertility cases. One of the causes of male infertility is the loss of spermatogonial stem cells, which may occur because of chemotherapy, radiotherapy or genetic defects. In numerous animal species, the evidence suggests the pineal gland and melatonin secretion in their reproductive activities are involved. Recently, considerable attention has pointed to the usage of melatonin in the treatment of diseases. Melatonin is associated with the regulation of circadian and seasonal rhythmic functions, immune system functions, retinal physiology, spermatogenesis and inhibition of tumour growth in different species. Several studies demonstrated that melatonin acts as an anti-apoptotic, anti-inflammatory, anticancer and antioxidant agent. Melatonin can also protect testicles and spermatogonia against oxidative damage, chemotherapy drugs, environmental radiation, toxic substances, hyperthermia, ischemia/reperfusion, diabetes-induced testicular damage, metal-induced testicular toxicity, improve sperm quality and it affects the testosterone secretion pathway by affecting Leydig cells. Therefore, the objective of this study is to investigate the biological effects of melatonin as a natural antioxidant on testicles and their disorders.

Melatonin through blockade of Hif-1α signaling mediates the anti-fibrosis under hypoxia in canine Sertoli cells

The hypoxic microenvironment of cryptorchidism is an important factor in the impairment and fibrosis of Sertoli cells which result in blood-testis barrier (BTB) destruction and spermatogenesis loss. Recent studies have shown that melatonin, a well-known pineal hormone exerts beneficial effects against pathological fibrosis in a various of organs. However, it is still unknown whether melatonin can regulate hypoxia-induced fibrosis of Sertoli cells. In this study we evaluate melatonin levels, and its synthesizing enzymes, AANAT and HIOMT expression patterns in canine cryptorchidism and contralateral normal testis. Results show abdominal testes presented low melatonin levels and AANAT and HIOMT expression compared with testes located in the scrotum. Moreover, we established a hypoxia-induced fibrosis model in canine Sertoli cells induced by cobalt chloride (CoCl₂) and found that melatonin inhibited the EMT markers expression and ECM production as well as Hif-1α expression of Sertoli cells in a dose-dependent manner. Furthermore, use of Lificiguat (synonyms YC-1, Hif-1α inhibitor) to interfere with the Hif-1α pathway showed a similar effect with melatonin suppression of the fibrosis in Sertoli cells. The results indicate that melatonin supplementation can alleviate the fibrosis process of Sertoli cells caused by hypoxia, which is associated with regulating the inhibition of Hif-1α signaling.

Hypoxic condition induced H3K27me3 modification of the LncRNA Tmem235 promoter thus supporting apoptosis of BMSCs

Bone marrow mesenchymal stem cells (BMSCs) have strong regenerative potential and show good application prospects for treating clinical diseases. However, in the process of BMSC transplantation for treating ischemic and hypoxic diseases, BMSCs have high rates of apoptosis in the hypoxic microenvironment of transplantation, which significantly affects the transplantation efficacy. Our previous studies have confirmed the key role of long non-coding RNA Tmem235 (LncRNA Tmem235) in the process of hypoxia-induced BMSC apoptosis and its downstream regulatory mechanism, but the upstream mechanism by which hypoxia regulates LncRNA Tmem235 expression to induce BMSC apoptosis is still unclear. Under hypoxic conditions, we found that the level of LncRNA Tmem235 promoter histone H3 lysine 27 trimethylation modification (H3K27me3) was significantly increased by CHIP-qPCR. Moreover, H3K27me3 cooperated with LncRNA Tmem235 promoter DNA methylation to inhibit the expression of LncRNA Tmem235 and promote apoptosis of BMSCs. To study the mechanism of hypoxia-induced modification of LncRNA Tmem235 promoter H3K27me3 in the hypoxia model of BMSCs, we detected the expression of H3K27 methylase and histone demethylase and found that only histone methylase enhancer of zeste homolog 2 (EZH2) expression was significantly upregulated. Knockdown of EZH2 significantly decreased the level of H3K27me3 modification in the LncRNA Tmem235 promoter. The EZH2 promoter region contains a hypoxia-responsive element (HRE) that interacts with hypoxia-inducible factor-1alpha (HIF-1α), which is overexpressed under hypoxic conditions, thereby promoting its overexpression. In summary, hypoxia promotes the modification of the LncRNA Tmem235 promoter H3K27me3 through the HIF-1α/EZH2 signaling axis, inhibits the expression of LncRNA Tmem235, and leads to hypoxic apoptosis of BMSCs. Our findings improve the regulatory mechanism of LncRNA Tmem235 during hypoxic apoptosis of BMSCs and provide a more complete theoretical pathway for targeting LncRNA to inhibit hypoxic apoptosis of BMSCs.

New insights into the reverse of chromium-induced reprotoxicity of pregnant mice by melatonin

Hexavalent chromium Cr(VI) is a well-known environmental toxic metal that causes reprotoxicity in pregnant females. There are currently no appropriate interventions or treatments for Cr(VI) exposure during pregnancy. Herein, the protective effect of melatonin (MLT) against Cr(VI)-induced reprotoxicity is investigated by administrating MLT to pregnant mice exposed to Cr(VI). The results indicate that MLT effectively alleviates Cr(VI)-induced adverse pregnancy outcomes, restoring the decreased fetal weight and increased fetal resorption and malformation caused by Cr(VI) exposure to normal levels. MLT reduces the negative effects of Cr(VI) on follicular atresia and the development of primordial follicle in the maternal ovarian, thereby mitigating the decline in the reserve of primordial follicles. MLT alleviates Cr(VI)-induced oxidative stress, hence reducing the excessive accumulation of malondialdehyde in the maternal ovary. MLT inhibits Cr(VI)-induced apoptosis of ovarian granulosa cells and the expression of cleaved caspase-3 in the ovary. MLT reduces the increase in serum follicle-stimulating hormone caused by Cr(VI) exposure, while elevating anti-Mullerian hormone levels. We demonstrate that MLT reverses Cr(VI)-induced reprotoxicity in pregnant mice, opening up a new avenue for treating reproductive defects caused by environmental stress.

Current understanding of hexavalent chromium [Cr(VI)] neurotoxicity and new perspectives

Hexavalent chromium [Cr(VI)] is a global environmental pollutant that increases risk for several types of cancers and is increasingly being recognized as a neurotoxicant. Traditionally, the brain has been viewed as a largely post-mitotic organ due to its specialized composition of neurons, and consequently, clastogenic effects were not considered in neurotoxicology. Today, we understand the brain is composed of at least eight distinct cell types - most of which continue mitotic activity throughout lifespan. We have learned these dividing cells play essential roles in brain and body health. This review focuses on Cr(VI), a potent clastogen and known human carcinogen, as a potentially neurotoxic agent targeting mitotic cells of the brain. Despite its well-established role as a human carcinogen, Cr(VI) neurotoxicity studies have failed to find a significant link to brain cancers. In the few studies that did find a link, Cr(VI) was identified as a risk for gliomas. Instead, in the human brain, Cr(VI) appears to have more subtle deleterious effects that can impair childhood learning and attention development, olfactory function, social memory, and may contribute to motor neuron diseases. Studies of Cr(VI) neurotoxicity with animal and cell culture models have demonstrated elevated markers of oxidative damage and redox stress, with widespread neurodegeneration. One study showed mice exposed to Cr(VI)-laden tannery effluent exhibited longer periods of aggressive behavior toward an "intruder" mouse and took longer to recognize mice previously encountered, recapitulating the social memory deficits observed in humans. Here we conducted a critical review of the available literature on Cr(VI) neurotoxicity and synthesize the collective observations to thoroughly evaluate Cr(VI) neurotoxicity - much remains to be understood and recognized.

The Effect of Global DNA Methylation on PDCD5 Expression in the PBMC of Occupational Chromate Exposed Workers

OBJECTIVES

To evaluate the alteration of protein of programmed cell death 5 (PDCD5) in peripheral blood mononuclear cells (PBMC) and DNA methylation caused by hexavalent chromium exposure.

METHODS

There were 112 workers and 56 controls in this study. The chromium in RBC and urine, PBMC with PDCD5+, DNA methylation, urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and score of DNA damage were measured.

RESULTS

In chromate exposed workers, the percent of PBMC with PDCD5+, urine 8-OHdG, and score of DNA damage were significantly higher, whereas global DNA methylation was significantly lower. The binary logistic regression and generalized linear mixed model analysis showed that the percent of PBMC with PDCD5+ was significantly associated with global DNA hypomethylation.

CONCLUSIONS

The aberrant DNA hypomethylation plays an important role in PBMC apoptosis of occupational hexavalent chromium exposure.

Melatonin Attenuates Chromium (VI)-Induced Spermatogonial Stem Cell/Progenitor Mitophagy by Restoration of METTL3-Mediated RNA N6-Methyladenosine Modification

Spermatogonial stem cells (SSCs) are the basis of spermatogenesis, and any damage to SSCs may result in spermatogenic disorder and male infertility. Chromium (Cr) (VI) is a proven toxin, mutagen, and carcinogen, perpetually detrimental to environmental organisms due to its intricate and enduring detoxification process in vivo. Despite this, the deleterious effects of Cr (VI) on SSCs and the underlying mechanisms remain poorly understood. In this study, we identified that Cr (VI) impaired male reproductive system in mouse testes and induced mitochondrial dynamic imbalance and mitophagy in SSCs/progenitors. Cr (VI) also downregulated the RNA N⁶-methyladenosine (m⁶A) modification levels in mitochondrial dynamic balance and mitophagy genes in SSCs/progenitors. Inspiringly, the toxic effects of Cr (VI) could be relieved by melatonin pretreatment. Melatonin alleviated Cr (VI)-induced damage to male reproductive system and autophagy in mouse testes. Melatonin also attenuated Cr (VI)-induced cell viability loss and reactive oxygen species (ROS) generation, as well as mitochondrial dynamic disorders and mitophagy in SSCs/progenitors. The protective roles of melatonin against Cr (VI)-induced mitophagy were exerted by restoration of METTL3-mediated RNA m⁶A modification and activation of mitochondrial fusion proteins MFN2 and OPA1, as well as inhibition of the mitophagy BNIP3/NIX receptor pathway. Thus, our study provides novel insights into the molecular mechanisms for RNA m⁶A modification underlying the gene regulatory network responsible for mitochondrial dynamic balance, and also lays new experimental groundwork for treatment of Cr (VI)-induced damage to male fertility.

The role of ATF6 in Cr(VI)-induced apoptosis in DF-1 cells

Hexavalent chromium (Cr(VI)) is a common heavy metal pollutant in environment and has been proved possessing the cytotoxicity. In this study, we aimed to investigate the role of activating transcription factor 6 (ATF-6) in apoptosis of chicken embryo fibroblasts cell line (DF-1) induced by Cr(VI). Firstly, DF-1 cells were exposed to Cr(VI) to establish the cytotoxicity model, then the cell apoptosis and ATF-6 protein level were analyzed. By silencing ATF-6 gene, changes of the apoptosis rate and apoptotic proteins were examined. To further explore the regulatory mechanism of ATF-6, endoplasmic reticulum (ER) stress, mitochondrial function, reactive oxygen species (ROS) level, as well as the related pathway were evaluated. Results showed that Cr(VI) can result in DF-1 cell apoptosis, along with mitochondrial membrane potential (MMP) reducing and ER stress. Meanwhile, ATF-6 silencing lowered the apoptosis rate and ER stress level, showing with the decrease of XBP-1, PERK, GRP78, Caspase-12, Cleaved Caspase-3 and the increase of Bcl-2. Further analysis found that ATF-6 silencing down-regulated ROS and caused MMP loss, suggesting that ATF-6 silencing inhibited Cr(VI)-induced mitochondrial damage. In conclusion, this study indicate that ATF-6 plays an important regulatory role in Cr(VI)-induced DF-1 cell apoptosis through the ER stress and mitochondrial pathway.

Environmental pollutants exposure and male reproductive toxicity: The role of epigenetic modifications

Male fertility rates have shown a progressive decrease in recent decades. There is a growing concern about the male reproductive dysfunction caused by environmental pollutants exposure, however the underlying molecular mechanisms are still not well understood. Epigenetic modifications play a key role in the biological responses to external stressors. Therefore, this review discusses the roles of epigenetic modifications in male reproductive toxicity induced by environmental pollutants, with a particular emphasis on DNA methylation, histone modifications and miRNAs. The available literature proposed that environmental pollutants can directly or cause oxidative stress and DNA damage to induce a variety of epigenetic changes, which lead to gene dysregulation, mitochondrial dysfunction and consequent male reproductive toxicity. However, future studies focusing on more kinds of epigenetic modifications and their crosstalk as well as epidemiological data are still required to fill in the current research gaps. In addition, the intrinsic links between pollutants-mediated epigenetic regulations and male reproduction-related physiological responses deserve to be further explored.

Nano-remediation of toxic heavy metal contamination: Hexavalent chromium [Cr(VI)]

The inexorable industrialization and modern agricultural practices to meet the needs of the increasing population have polluted the environment with toxic heavy metals such as Cr(VI), Cu²⁺, Cd²⁺, Pb^2+, and Zn²⁺. Among the hazardous heavy metal(loid)s contamination in agricultural soil, water, and air, hexavalent chromium [Cr(VI)] is the most virulent carcinogen. The metallurgic industries, tanneries, paint manufacturing, petroleum refineries are among various such human activities that discharge Cr(VI) into the environment. Various methods have been employed to reduce the concentration of Cr(VI) contamination with nano and bioremediation being the recent advancement to achieve recovery at low cost and higher efficiency. Bioremediation is the process of using biological sources such as plant extracts, microorganisms, and algae to reduce the heavy metals while the nano-remediation uses nanoparticles to adsorb heavy metals. In this review, we discuss the various activities that liberate Cr(VI). We then discuss the various conventional, nano-remediation, and bioremediation methods to keep Cr(VI) concentration in check and further discuss their efficiencies. We also discuss the mechanism of nano-remediation techniques for better insight into the process.

Assessment of Mechanistic Data for Hexavalent Chromium-Induced Rodent Intestinal Cancer Using the Key Characteristics of Carcinogens

Oral exposure to hexavalent chromium (Cr[VI]) induces intestinal tumors in mice. Mutagenic and nonmutagenic modes of action (MOAs) have been accepted by different regulatory bodies globally, the latter involving cytotoxicity-induced regenerative cell proliferation. However, concerns persist that all possible MOAs have not been fully considered. To address the potential for alternative MOAs, mechanistic data not represented in the existing two MOAs were evaluated. Relevant data were identified and organized by key characteristics of carcinogens (KCCs); literature related to epigenetics, immunosuppression, receptor-mediated effects, and immortalization were reviewed to identify potential key events associated with an alternative MOA. Over 200 references were screened for these four KCCs and further prioritized based on relevance to the research objective (ie, in vivo, oral exposure, gastrointestinal tissue). Minimal data were available specific to the intestine for these KCCs, and there was no evidence of any underlying mechanisms or key events that are not already represented in the two proposed MOAs. For example, while epigenetic dysregulation of DNA repair genes has been demonstrated, epigenetic effects were not measured in intestinal tissue, and it has been shown that Cr(VI) does not cause DNA damage in intestinal tissue. High-throughput screening data related to the KCCs were also evaluated, with activity generally limited to the two recognized MOAs. Collectively, no plausible alternative MOAs (or key events) were identified in addition to those previously proposed for Cr(VI) small intestine tumors.

Metformin improves boar sperm quality via 5'-AMP-activated protein kinase-mediated energy metabolism in vitro

Sperm are specialized cells that require adenosine triphosphate (ATP) to support their function. Maintaining sperm energy homeostasis in vitro is vitally important to improve the efficacy of boar sperm preservation. Metformin can activate 5′-AMP-activated protein kinase (AMPK) to improve metabolic flexibility and maintain energy homeostasis. Thus, the aim of the present study was to investigate whether metformin can improve boar sperm quality through AMPK mediation of energy metabolism. Sperm motility parameters, membrane integrity, acrosome integrity, mitochondrial membrane potential (ΔΨ_m), ATP content, glucose uptake, and lactate efflux were analyzed. Localization and expression levels of AMPK and phospho-Thr¹⁷²-AMPK (p-AMPK) were also detected by immunofluorescence and western blotting. We found that metformin treatment significantly increased sperm motility parameters, ΔΨ_m, and ATP content during storage at 17 °C. Moreover, results showed that AMPK was localized at the acrosomal region, connecting piece, and midpiece of sperm and p-AMPK was distributed at the post-acrosomal region, connecting piece, and midpiece. When sperm were incubated with metformin for 4 h at 37 °C, sperm motility parameters, ΔΨ_m, ATP content, p-AMPK, glucose uptake, and lactate efflux all significantly increased, whereas the addition of Compound C treatment, an inhibitor of AMPK, counteracted these positive effects. Together, our results suggest that metformin promotes AMPK activation, which contributes to the maintenance of energy hemostasis and mitochondrial activity, thereby maintaining boar sperm functionality and improving the efficacy of semen preservation.

The capability of coenzyme Q10 to enhance heat tolerance in male rabbits: evidence from improved semen quality factor (SQF), testicular oxidative defense, and expression of testicular melatonin receptor MT1

Heat stress (HS) has a great influence on the etiology of male infertility. Coenzyme Q10 (CoQ10), known to have powerful antioxidant effects, has been reported to have such actions that are effective to treat infertility caused by HS. The aim of the present study was to investigate the antioxidative effect of CoQ10 on sperm quality, testicular antioxidant activities, and male fertility under HS. For this purpose, 18 mature male rabbits (aged 22 wk) of the Sinai Gabali breed were equally divided into 3 groups and placed at temperature-humidity index of 29 for 8 wk at a farm. The supplementation of CoQ10 at 0, 10, and 20 mg/kg of body weight was done in the first, second, and third groups, respectively. The results showed that the supplementation of CoQ10 had significant (P < 0.05) effect on semen quality factor (SQF) and testicular antioxidant activities by the supplementation of CoQ10. Moreover, a significant improvement in the concentration of testosterone, integrity of testicular DNA, and the expression of melatonin receptors was also observed, which were consistent with a significant improvement in buck fertility. The prolificacy was significantly increased (P < 0.05) in females when inseminated from bucks that were treated with CoQ10. Our results suggest that CoQ10 tends to decrease oxidative stress by enhancing testicular antioxidant activities, which are considered the most important factors for a buck's fertility. Hence, CoQ10 could be a suitable feed supplement to increase fertility, through enhancing the semen quality, in male rabbits and reducing the harmful effects of HS.

Epigenetic Regulation of Spermatogonial Stem Cell Homeostasis: From DNA Methylation to Histone Modification

Spermatogonial stem cells(SSCs)are the ultimate germline stem cells with the potential of self-renewal and differentiation, and a dynamic balance of SSCs play an essential role in spermatogenesis. During the gene expression process, genomic DNA and nuclear protein, working together, contribute to SSC homeostasis. Recently, emerging studies have shown that epigenome-related molecules such as chromatin modifiers play an important role in SSC homeostasis through regulating target gene expression. Here, we focus on two types of epigenetic events, including DNA methylation and histone modification, and summarize their function in SSC homeostasis. Understanding the molecular mechanism during SSC homeostasis will promote the recognition of epigenetic biomarkers in male infertility, and bring light into therapies of infertile patients.Graphical Abstract.

Environmental Impact on Male (In)Fertility via Epigenetic Route

In the last 40 years, male reproductive health-which is very sensitive to both environmental exposure and metabolic status-has deteriorated and the poor sperm quality observed has been suggested to affect offspring development and its health in adult life. In this scenario, evidence now suggests that epigenetics shapes endocrine functions, linking genetics and environment. During fertilization, spermatozoa share with the oocyte their epigenome, along with their haploid genome, in order to orchestrate embryo development. The epigenetic signature of spermatozoa is the result of a dynamic modulation of the epigenetic marks occurring, firstly, in the testis-during germ cell progression-then, along the epididymis, where spermatozoa still receive molecules, conveyed by epididymosomes. Paternal lifestyle, including nutrition and exposure to hazardous substances, alters the phenotype of the next generations, through the remodeling of a sperm epigenetic blueprint that dynamically reacts to a wide range of environmental and lifestyle stressors. With that in mind, this review will summarize and discuss insights into germline epigenetic plasticity caused by environmental stimuli and diet and how spermatozoa may be carriers of induced epimutations across generations through a mechanism known as paternal transgenerational epigenetic inheritance.

Global changes in epigenomes during mouse spermatogenesis: possible relation to germ cell apoptosis

Mammalian spermatogenesis is characterized by disproportionate germ cell apoptosis. The high frequency of apoptosis is considered a safety mechanism that serves to avoid unfavorable transmission of paternal aberrant genetic information to the offspring as well as elimination mechanism for removal of overproduced immature or damaged spermatogenic cells. The molecular mechanisms involved in the induction of germ cell apoptosis include both intrinsic mitochondrial Bcl-2/Bax and extrinsic Fas/FasL pathways. However, little is known about the nuclear trigger of those systems. Recent studies indicate that epigenomes are essential in the regulation of gene expression through remodeling of the chromatin structure, and are genome-like transmission materials that reflect the effects of various environmental factors. In spermatogenesis, epigenetic errors can act as the trigger for elimination of germ cells with abnormal chromatin structure, abnormal gene expression and/or morphological defects (disordered differentiation). In this review, we focus on the relationship between global changes in epigenetic parameters and germ cell apoptosis in mice and other mammals.

Melatonin inhibits apoptosis in mouse Leydig cells via the retinoic acid-related orphan nuclear receptor α/p53 pathway

Melatonin is an endogenous indoleamine hormone involved in various physiological processes. However, the mechanism of melatonin in mediating Leydig cells function has not been fully explained. In this study, we investigated the mechanism through which melatonin inhibits apoptosis in mouse Leydig cells by activating the retinoic acid-related orphan nuclear receptor (ROR) α/p53 signaling pathway. We confirmed the expression and localization of RORα in mouse Leydig cells using immunofluorescence. After treatment with 10 ng/mL melatonin for 36 h, RORα mRNA and protein levels were significantly increased (P < 0.01). TUNEL and flow cytometry showed that melatonin significantly decreased the TUNEL-positive cell ratio and apoptosis rate (P < 0.05). Moreover, melatonin decreased BAX expression and increased BCL-2 expression (P < 0.05). However, the RORα inhibitor SR1001 reversed the inhibitory effects of melatonin on apoptosis (P < 0.05). Additionally, analysis of p53 expression showed that melatonin inhibited p53 mRNA and protein expression (P < 0.05), whereas SR1001 reversed these effects. p53 reversed the anti-apoptotic process involving RORα-mediated melatonin in mouse Leydig cells. Collectively, our findings suggested that melatonin inhibited apoptosis via the RORα/p53 pathway.

Environmentally relevant concentration of chromium induces nuclear deformities in erythrocytes and alters the expression of stress-responsive and apoptotic genes in brain of adult zebrafish

Heavy metal contamination of water body has become a serious threat to aquatic life forms specially to fish. Hexavalent chromium (Cr [VI]) is one of the most potent heavy metal toxicant. It is present in aquatic environment at concentrations beyond permissible limit. Considering the fact that toxic effects are function of the exposure concentration, studies involving toxicological risk assessment should be done at environmentally relevant concentration. Therefore we studied the toxic effects of Cr [VI] to zebrafish at an environmentally relevant concentration (2 mg L^-1). We monitored the genotoxic potential of Cr [VI] in erythrocytes through a simple reliable microscopic assay and found an increase in frequency of micronucleated erythrocytes along with erythrocytes with blebbed, lobed and notched nuclei. In addition, Cr [VI] induced neurotoxicity, being a least reported event was also investigated. Histological alterations in brain, elevated GSH and MDA content and increased catalase activity indicated oxidative stress-mediated damage. This was further confirmed through expressional alteration of Ucp2. Upregulation of Nrf2, Nqo1 and Ho1 clearly indicated the involvement of Nrf2-ARE system in stress response against Cr [VI] induced neurotoxicity. The transcriptional induction of apoptotic genes such as Bax, Caspase 9 and Caspase 3 along with downregulation of Bcl2 indicated that the cytoprotective system failed to counter the induced stress. Interestingly, there was upregulation of AChE gene, which could be correlated with the upregulated apoptotic genes. This study provides an insight on the neurotoxic stress of Cr [VI] on the zebrafish yet at an environmentally relevant concentration. Moreover the induction of nuclear anomalies in the erythrocytes can serve as extremely sensitive endpoints of toxicological stress indicators of aquatic contaminants like Cr [VI].

Melatonin protects the mouse testis against heat-induced damage

Spermatogenesis, an intricate process occurring in the testis, is responsible for ongoing production of spermatozoa and thus the cornerstone of lifelong male fertility. In the testis, spermatogenesis occurs optimally at a temperature 2–4°C lower than that of the core body. Increased scrotal temperature generates testicular heat stress and later causes testicular atrophy and spermatogenic arrest, resulting in a lower sperm yield and therefore impaired male fertility. Melatonin (N-acetyl-5-methoxytryptamine), a small neuro-hormone synthesized and secreted by the pineal gland and the testis, is widely known as a potent free-radical scavenger; it has been reported that melatonin protects the testis against inflammation and reactive oxygen species generation thereby playing anti-inflammatory, -oxidative and -apoptotic roles in the testis. Nevertheless, the role of melatonin in the testicular response to heat stress has not been studied. Here, by employing a mouse model of testicular hyperthermia, we systematically investigated the testicular response to heat stress as well as the occurrence of autophagy, apoptosis and oxidative stress in the testis. Importantly, we found that pre-treatment with melatonin attenuated heat-induced apoptosis and oxidative stress in the testis. Also, post-treatment with melatonin promoted recovery of the testes from heat-induced damage, probably by maintaining the integrity of the Sertoli cell tight-junction. Thus, we for the first time provide the proof of concept that melatonin can protect the testis against heat-induced damage, supporting the potential future use of melatonin as a therapeutic drug in men for sub/infertility incurred by various testicular hyperthermia factors.

Advances in Characterizing Recently-Identified Molecular Actions of Melatonin: Clinical Implications

Melatonin, N-acetyl-5-methoxy-tryptamine, was discovered to be a product of serotonin metabolism in the mammalian pineal gland where its synthesis is under control of the light:dark cycle. Besides its regulatory pathway involving ganglion cells in the retina, the neural connections between the eyes and the pineal gland include the master circadian clock, the suprachiasmatic nuclei, and the central and peripheral nervous systems. Since pineal melatonin is released into the blood and into the cerebrospinal fluid, it has access to every cell in an organism and it mediates system-wide effects. Subsequently, melatonin was found in several extrapineal organs and, more recently, perhaps in every cell of every organ. In contrast to the pinealocytes, non-pineal cells do not discharge melatonin into the blood; rather it is used locally in an intracrine, autocrine, or paracrine manner. Melatonin levels in non-pineal cells do not exhibit a circadian rhythm and do not depend on circulating melatonin concentrations although when animals are treated with exogenous melatonin it is taken up by presumably all cells. Mitochondria are the presumed site of melatonin synthesis in all cells; the enzymatic machinery for melatonin synthesis has been identified in mitochondria. The association of melatonin with mitochondria, because of its ability to inhibit oxidative stress, is very fortuitous since these organelles are a major site of damaging reactive oxygen species generation. In this review, some of the actions of non-pineal-derived melatonin are discussed in terms of cellular and subcellular physiology.

Melatonin Inhibits Apoptosis and Oxidative Stress of Mouse Leydig Cells via a SIRT1-Dependent Mechanism

The purpose of the present study is to examine the effects of melatonin on apoptosis and oxidative stress in mouse Leydig cells and to elucidate the mechanisms responsible for these effects. Our results indicated that 10 ng/mL of melatonin significantly promoted cell viability, the ratio of EdU-positive (5-Ethynyl-2'-deoxyuridine) cells, and increased the mRNA expression of proliferating cell nuclear antigen (PCNA), cyclin D1(CCND1), and cell division control protein 42 (CDC42) (p < 0.05). We also observed that melatonin inhibited apoptosis of mouse Leydig cells, accompanied with increased B-cell lymphoma-2 (BCL-2) and decreased BCL2 associated X (BAX) mRNA and protein expression. Moreover, addition of melatonin significantly decreased the reactive oxygen species (ROS) production and malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, while it increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels (p < 0.05). In addition, we also found that melatonin increased the expression of SIRT1 (Silent information regulator 1) (p < 0.05). To explore the role of SIRT1 signaling in melatonin-induced cells, mouse Leydig cells were pretreated with EX527, an inhibitor of SIRT1. The protective effects of melatonin on mouse Leydig cells were reversed by EX527, as shown by decreased cell proliferation and increased cell apoptosis and oxidative stress. In summary, our results demonstrated that melatonin inhibited apoptosis and oxidative stress of mouse Leydig cells through a SIRT1-dependent mechanism.

Maternal exposure to traffic pollutant causes impairment of spermatogenesis and alterations of genome-wide mRNA and microRNA expression in F2 male mice

Male spermatogenesis dysfunctions are associated with environmental pollutants, but the detailed mechanisms remain poorly understood. In this study, healthy C57BL/6 J mice were used to establish an animal model of maternal exposure to traffic pollutant during pregnancy, and the toxic effects on the reproductive system of F2 male mice were analysed using mRNA and miRNA microarray. Our results showed that 54 miRNAs and 1927 mRNAs were significantly altered in the exposed group. Gene Ontology (GO) analysis revealed that the most significant GO terms for biological process, molecular function and cellular component were myeloid cell differentiation, growth factor binding and main axon. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that the biosynthesis of amino acids was the most significant pathway and that the cytokine-cytokine receptor interaction was the most abundant pathway (37 genes). Protein-protein interaction (PPI) and the miRNA-mRNA network were constructed with Cytoscape. The hub genes, Tnf, Il10 and Gapdh, were closely related to immuno-regulation and their miRNA regulators were reversely changed. Together, our results indicate that maternal exposure to traffic pollutant can cause spermatogenesis damage in F2 male mice possibly through the destroyed immunoprivileged environment in testis mediated by the aberrant expression of miRNA and mRNA.

Melatonin Mitigates Mitochondrial Meltdown: Interactions with SIRT3

Melatonin exhibits extraordinary diversity in terms of its functions and distribution. When discovered, it was thought to be uniquely of pineal gland origin. Subsequently, melatonin synthesis was identified in a variety of organs and recently it was shown to be produced in the mitochondria. Since mitochondria exist in every cell, with a few exceptions, it means that every vertebrate, invertebrate, and plant cell produces melatonin. The mitochondrial synthesis of melatonin is not photoperiod-dependent, but it may be inducible under conditions of stress. Mitochondria-produced melatonin is not released into the systemic circulation, but rather is used primarily in its cell of origin. Melatonin's functions in the mitochondria are highly diverse, not unlike those of sirtuin 3 (SIRT3). SIRT3 is an NAD+-dependent deacetylase which regulates, among many functions, the redox state of the mitochondria. Recent data proves that melatonin and SIRT3 post-translationally collaborate in regulating free radical generation and removal from mitochondria. Since melatonin and SIRT3 have cohabitated in the mitochondria for many eons, we predict that these molecules interact in many other ways to control mitochondrial physiology. It is predicted that these mutual functions will be intensely investigated in the next decade and importantly, we assume that the findings will have significant applications for preventing/delaying some age-related diseases and aging itself.