Regulation of Leydig cell steroidogenesis: intriguing network of signaling pathways and mitochondrial signalosome

Cell-type specific and differential expression of LINC-RSAS long noncoding RNA declines in the testes during ageing of the rat

Long noncoding RNAs (lncRNAs) have emerged as major regulators of gene expression, chromatin structure, epigenetic changes, post-transcriptional processing of RNAs, translation of mRNAs into proteins as well as contributing to the process of ageing. Ageing is a universal, slow, progressive change in almost all physiological processes of organisms after attaining reproductive maturity and often associated with age-related diseases. Mammalian testes contain various cell-types, vast reservoir of transcriptome complexity, produce haploid male gametes for reproduction and testosterone for development and maintenance of male sexual characters as well as contribute genetic variation to the species. We report age-related decline in expression and cellular localization of Long intergenic noncoding repeat-rich sense-antisense (LINC-RSAS) RNA in the testes and its major cell-types such as primary spermatocytes, Leydig cells and Sertoli cells during ageing of the rat. LINC-RSAS expression in testes increased from immature (4-weeks) to adult (16- and 44-weeks) and declined from adult (44-weeks) to nearly-old (70-weeks) rats. Genomic DNA methylation in the testes showed a similar pattern. Cell-type specific higher expression of LINC-RSAS was observed in primary spermatocytes (pachytene cells), Leydig cells and Sertoli cells of testes of adult rats. Over-expression of LINC-RSAS in cultured human cell lines revealed its possible role in cell-cycle control and apoptosis. We propose that LINC-RSAS expression is involved in molecular physiology of primary spermatocytes, Leydig cells and Sertoli cells of adult testes and its decline is associated with diminishing function of testes during ageing of the rat.

Toward understanding the role of the interstitial tissue architects: Possible functions of telocytes in the male gonad

Telocytes represent a relatively recently discovered population of interstitial cells with a unique morphological structure that distinguishes them from other neighboring cells. Through their long protrusions extending from the cell body, telocytes create microenvironments via tissue compartmentalization and create homo- and hetero-cellular junctions. These establish a three-dimensional network enabling the maintenance of interstitial compartment homeostasis through regulation of extracellular matrix organization and activity, structural support, paracrine and juxtracrine communication, immunomodulation, immune surveillance, cell survival, and apoptosis. The presence of telocytes has also been confirmed in testicular interstitial tissue of many species of animals. The objective of this review is to summarize recent findings on telocytes in the male gonad, on which conclusions have been deduced that indicate the involvement of telocytes in maintaining the cytoarchitecture of the testicular interstitial tissue, in the processes of spermatogenesis and steroidogenesis, and photoperiod-mediated changes in the testes in seasonally reproductive animals.

Interacting with luteinizing hormone receptor provides a new elucidation of the mechanism of anti-androgenicity of bisphenol S

Bisphenol S (BPS) exhibited inhibitory effects on androgen synthesis, but its target of action remains unclear. We investigated the effects of BPS exposure at environmentally relevant concentrations (1 μg/L, 10 μg/L and 100 μg/L) for 48 h on androgen synthesis in rat ovarian theca cells and explored the underlying mechanisms, target site and target molecule. The results showed that BPS exposure inhibited the transcript levels of steroidogenic genes and reduced the contents of androgen precursors, testosterone and dihydrotestosterone. BPS exposure decreased the phosphorylation levels of extracellular signal-related kinase 1/2 (ERK1/2), and the inhibitory effects of BPS on testosterone content and steroidogenic gene expression were blocked by ERK1/2 agonist LY2828360, suggesting that ERK1/2 signaling pathway mediates the inhibitory effects of BPS on androgen synthesis. BPS mainly accumulated on the cell membrane, impermeable BPS-bovine serum albumin exposure still inhibited androgen synthesis, BPS interacted with rat luteinizing hormone receptor (LHR) via formation of hydrogen bonds in the transmembrane region, and the inhibitory effects of BPS on ERK1/2 phosphorylation were blocked by luteinizing hormone (the natural agonist of LHR), indicating that LHR located on the cell membrane is the target of action of BPS. This paper provides a new elucidation of the mechanism of anti-androgenicity of BPS, especially for the non-genomic pathways.

Cytotoxicity, morphological and ultrastructural effects induced by the neonicotinoid pesticide, imidacloprid, using a rat Leydig cell line (LC-540)

Imidacloprid is a systemic neonicotinoid insecticide widely used to combat agricultural pests and flea infestations in dogs and cats. Despite its low toxicity to mammals, imidacloprid is reported to cause male reproductive toxicity. This study evaluated the cytotoxic effects of 75-800 μM imidacloprid on a rat Leydig cell line (LC-540). The effect of exposure to 300, 400, and 500 µM imidacloprid on selected cytoskeletal proteins, mitochondrial morphology, lysosomal acidity, and ultrastructure were investigated. Cell viability was markedly reduced after 48 and 72 h of exposure to higher imidacloprid concentrations. The immunocytochemical analysis revealed that the cytoskeletal filaments exhibited disorganization, disruption, and perinuclear aggregation in treated LC-540 cells. Ultrastructurally, cytoplasmic vacuoles, autophagic vacuoles, lysosomes, and mitochondrial damage were detected. Changes in the mitochondrial morphology and lysosomes induced by imidacloprid were confirmed. The cytotoxicity of imidacloprid observed in LC-540 cells might be due to its mitochondrial damage and cytoskeletal protein disruption.

Effect of Cycas pectinata Seed Extract on Testicular Steroidogenesis in a Mouse Model

The seed of Cycas pectinata is widely used in traditional practices in the Northeastern region of India for diverse purposes along with improving testicular functions. Thus, it may be hypothesized that the phytochemicals of C. pectinata seed could modulate testicular steroidogenesis. Therefore, we have investigated the effects of C. Pectinata seed extract (CPE) on testicular steroidogenesis by using in vivo and in vitro approaches. We have also performed the molecular docking of phytochemicals with some steroidogenic markers based on the identified phytochemicals from our previous study. The in vivo treatment of CPE increased the circulating estrogen and decreased circulating testosterone. The in vitro treatment of CPE also showed increased secretion of estrogen which can be suggested due to an increase in the aromatase (CYP19A1) activity. Our results also showed that the expression and localization of CYP19A1 were elevated by the CPE. The treatment of CPE also showed an accumulation of cholesterol in the testis, which could enhance testicular steroidogenesis. The other steroidogenic markers like 3βHSD, StAR, and LHR were upregulated by the CPE. Twelve compounds exhibited binding energy in the range of -10.0 to -8.0 kcal/mol with CYP19A1. Our data from in vitro, in vivo, and docking studies, showed that phytochemicals of CPE could modulate testicular steroidogenesis.

Glycine protects the male reproductive system against lead toxicity via alleviating oxidative stress, preventing sperm mitochondrial impairment, improving kinematics of sperm, and blunting the downregulation of enzymes involved in the steroidogenesis

Lead (Pb) is a highly toxic heavy metal widely dispersed in the environment because of human industrial activities. Many studies revealed that Pb could adversely affect several organs, including the male reproductive system. Pb-induced reproductive toxicity could lead to infertility. Thus, finding safe and clinically applicable protective agents against this complication is important. It has been found that oxidative stress plays a fundamental role in the pathogenesis of Pb-induced reprotoxicity. Glycine is the simplest amino acid with a wide range of pharmacological activities. It has been found that glycine could attenuate oxidative stress and mitochondrial impairment in various experimental models. The current study was designed to evaluate the role of glycine in Pb-induced reproductive toxicity in male mice. Male BALB/c mice received Pb (20 mg/kg/day; gavage; 35 consecutive days) and treated with glycine (250 and 500 mg/kg/day; gavage; 35 consecutive days). Then, reproductive system weight indices, biomarkers of oxidative stress in the testis and isolated sperm, sperm kinetic, sperm mitochondrial indices, and testis histopathological alterations were monitored. A significant change in testis, epididymis, and Vas deferens weight was evident in Pb-treated animals. Markers of oxidative stress were also significantly increased in the testis and isolated sperm of the Pb-treated group. A significant disruption in sperm kinetic was also evident when mice received Pb. Moreover, Pb exposure caused significant deterioration in sperm mitochondrial indices. Tubular injury, tubular desquamation, and decreased spermatogenic index were histopathological alterations detected in Pb-treated mice. It was found that glycine significantly blunted oxidative stress markers in testis and sperm, improved sperm mitochondrial parameters, causing considerable higher velocity-related indices (VSL, VCL, and VAP) and percentages of progressively motile sperm, and decreased testis histopathological changes in Pb-exposed animals. These data suggest glycine as a potential protective agent against Pb-induced reproductive toxicity. The effects of glycine on oxidative stress markers and mitochondrial function play a key role in its protective mechanism.

Zingerone attenuates zearalenone-induced steroidogenesis impairment and apoptosis in TM3 Leydig cell line

Zingerone¹ (Zing) is one of the bioactive compounds of ginger rhizome (Zingiber officinale), whose beneficial effects have been reported previously on reproductive organ complications. The current study purposed to survey probable protective impacts of Zing against Zearalenone (ZEA)-induced changes in the TM3 Leydig cell line. Exposure of TM3 cells to ZEA (25 μM) attenuates the levels of testosterone and steroidogenesis-related genes, which was reversed by 25 μM of Zing. ZEA also induced ROS generation and apoptosis in TM3 cells. Zing treatment improved the stress oxidative and apoptosis-related changes induced by ZEA in TM3 cells by modulating autophagy-related proteins and activating PI3K-AKT-mTOR and Nrf2 pathways. The findings of this study represented a theoretical basis for Zing's protective actions against ZEA toxic effects on TM3 cells.

Decreased expression of AKAP4 and TyrPho proteins in testis, epididymis, and spermatozoa with low sexual performance of mice induced by modified CUMS

The molecular mechanism of chronic stress especially reduced motility, a major cause of male infertility, has not been proved. It is known that A-kinase anchor protein 4 (AKAP4) and tyrosine-phosphorylated (TyrPho) proteins are involved in progressive motility. This study aimed to investigate the effect of chronic unpredictable mild stress (CUMS) on sexual behaviours, sperm quality, and expressions of AKAP4 and TyrPho proteins in testis, epididymis, and spermatozoa. Sixteen male mice were divided into control and CUMS groups (n = 8/group). Animals were induced by a stressor from twelve stressors for 36 days. Sexual behaviours, corticosterone and testosterone, sperm parameters, and histopathology were observed. The expressions of AKAP4 and TyrPho proteins in testis, epididymis, and spermatozoa were examined. Results showed that CUMS significantly increased corticosterone while serum testosterone level was decreased. Sexual behaviours and sperm parameter quality were significantly decreased. CUMS mice showed vacuolisation and pyknotic cells in seminiferous epithelium and less sperm mass was observed within epididymal lumen. CUMS decreased expressions of AKAP4 and TyrPho proteins in testis, epididymis, and spermatozoa. In conclusion, the decreased expression of AKAP4 and TyrPho proteins may be a mechanism associated with low semen qualities particularly decrease of sperm motility in CUMS.

Acrolein exerts a genotoxic effect in the Leydig cells by stimulating DNA damage-induced apoptosis

Acrolein is a highly reactive unsaturated organic molecule and has harmful effects on human health. Acrolein is generally formed in heat-treated foods above 150 °C, as well as in the combustion of gasoline, wood industry, plastic waste, and tobacco smoke. In this study, the effects of acrolein on genotoxicity in Leydig cells and the underlying mechanisms are aimed to be clarified. In addition, the toxicogenomic profile of acrolein was studied in terms of both apoptosis and steroidogenesis. Real-time PCR and ELISA tests were used to analyses of steroidogenic endpoints. Apoptosis was evaluated with double fluorescence staining and gene expression analyses of related genes. Comet assay was used to determine the genotoxicity. The results showed that acrolein caused concentration-dependent inhibition on cell viability at 8 μM and above concentrations, decreased testosterone production at 13.6 and 19.7 μM concentrations, and suppressed expression levels of genes that play an important role in steroidogenic pathway. Furthermore, acrolein downregulated expression of anti-apoptotic Bcl2 gene and upregulated expression of pro-apoptotic Bax, Casp3, and Trp53 gene after 24-h treatment in 7.4, 13.6, and 19.7 μM acrolein-exposed Leydig cells. The results of comet assay showed that acrolein significantly induced tail length, tail % DNA, and Olive tail moment. Overall, it was concluded that acrolein-induced cell damage in Leydig cells may be due to formation of genetic damage in steroidogenesis and apoptosis.