Effect of heat stress on expression of junction-associated molecules and upstream factors androgen receptor and Wilms' tumor 1 in monkey sertoli cells

Comparing the Effect of Heat Therapy and Mitochondrial-Targeted Antioxidants in Polycystic Ovarian Syndrome Phenotype Induced by Junk Food Consumption

Polycystic ovarian syndrome (PCOS) is a complex endocrine-metabolic disorder, and multiple factors contribute to its pathophysiology. The current study assessed a PCOS-like animal model induced by consuming a high-fat sugar (HFHS) diet and compared the treatment outcome of mitochondrial-targeted antioxidants versus heat therapy. Sixty rats were divided into the following study groups: three control groups (negative and positive for the treatments used), HFHS, hot tub therapy (HTT) treatment, and MitoQ10 treatment (500 µmol/L MitoQ10 in clean drinking water daily, from week fourteen till week twenty-two of the study). At week fourteen, PCOS was confirmed by vaginal smear examination; measurements of blood testosterone (T), anti-Mullerian hormone (AMH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), glucose, and insulin; and determination of the homeostatic model assessment of IR (HOMA-IR). At week 22, blood samples were collected for measurement of the serum LH, FSH, AMH, T, insulin, glucose, lipid profile, kisspeptin, ADAM metallopeptidase with thrombospondin type 1 motif 19 (ADAMTS19), S100 calcium-binding protein B (S100B), fibulin 1 (FBLN1), immunoglobulin free light chains (FLCs), kappa and lambda. Ovaries were examined for morphological changes; for the levels of glutathione (GSH), catalase, SOD, malondialdehyde (MDA), and nitric oxide (NO); and the expression of FK506 binding protein 52 (FKBP52) and the androgen receptor (AR). The consumption of HFHS diet-induced PCOS-like features, which have been ameliorated by both HTT and mitoQ10 as potential therapies, with MitoQ10 showing a superior effect over HTT.

Classical cadherins in the testis: how are they regulated?

Cadherins (CDH) are crucial intercellular adhesion molecules, contributing to morphogenesis and creating tissue barriers by regulating cells' movement, clustering and differentiation. In the testis, classical cadherins such as CDH1, CDH2 and CDH3 are critical to gonadogenesis by promoting the migration and the subsequent clustering of primordial germ cells with somatic cells. While CDH2 is present in both Sertoli and germ cells in rodents, CDH1 is primarily detected in undifferentiated spermatogonia. As for CDH3, its expression is mainly found in germ and pre-Sertoli cells in developing gonads until the establishment of the blood-testis barrier (BTB). This barrier is made of Sertoli cells forming intercellular junctional complexes. The restructuring of the BTB allows the movement of early spermatocytes toward the apical compartment as they differentiate during a process called spermatogenesis. CDH2 is among many junctional proteins participating in this process and is regulated by several pathways. While cytokines promote the disassembly of the BTB by enhancing junctional protein endocytosis for degradation, testosterone facilitates the assembly of the BTB by increasing the recycling of endocytosed junctional proteins. Mitogen-activated protein kinases (MAPKs) are also mediators of the BTB kinetics in many chemically induced damages in the testis. In addition to regulating Sertoli cell functions, follicle stimulating hormone can also regulate the expression of CDH2. In this review, we discuss the current knowledge on regulatory mechanisms of cadherin localisation and expression in the testis.

Heat stress and stallion fertility

The threat posed by increased surface temperatures worldwide has attracted the attention of researchers to the reaction of animals to heat stress. Spermatogenesis in animals such as stallions is a temperature-dependent process, ideally occurring at temperatures slightly below the core body temperature. Thus, proper thermoregulation is essential, especially because stallion spermatogenesis and the resulting spermatozoa are negatively affected by increased testicular temperature. Consequently, the failure of thermoregulation resulting in heat stress may diminish sperm quality and increase the likelihood of stallion infertility. In this review, we emphasize upon the impact of heat stress on spermatogenesis and the somatic and germ cells and describe the subsequent testicular alterations. In addition, we explore the functions and molecular responses of heat shock proteins, including HSP60, HSP70, HSP90, and HSP105, in heat-induced stress conditions. Finally, we discuss the use of various therapies to alleviate heat stress-induced reproductive harm by modulating distinct signaling pathways.

Combinatorial Network of Transcriptional and miRNA Regulation in Colorectal Cancer

Colorectal cancer is one of the leading causes of cancer-associated mortality across the worldwide. One of the major challenges in colorectal cancer is the understanding of the regulatory mechanisms of biological molecules. In this study, we aimed to identify novel key molecules in colorectal cancer by using a computational systems biology approach. We constructed the colorectal protein–protein interaction network which followed hierarchical scale-free nature. We identified TP53, CTNBB1, AKT1, EGFR, HRAS, JUN, RHOA, and EGF as bottleneck-hubs. The HRAS showed the largest interacting strength with functional subnetworks, having strong correlation with protein phosphorylation, kinase activity, signal transduction, and apoptotic processes. Furthermore, we constructed the bottleneck-hubs’ regulatory networks with their transcriptional (transcription factor) and post-transcriptional (miRNAs) regulators, which exhibited the important key regulators. We observed miR-429, miR-622, and miR-133b and transcription factors (EZH2, HDAC1, HDAC4, AR, NFKB1, and KLF4) regulates four bottleneck-hubs (TP53, JUN, AKT1 and EGFR) at the motif level. In future, biochemical investigation of the observed key regulators could provide further understanding about their role in the pathophysiology of colorectal cancer.

Effects of bisphenol A and estradiol in adult rat testis after prepubertal and pubertal exposure

Over the past few decades, male fertility has been decreasing worldwide. Many studies attribute this outcome to endocrine disruptors exposure such as bisphenol A (BPA), which is a chemical compound used in plastics synthesis and exhibiting estrogenic activity. In order to assess how the window of exposure modulates the effects of BPA on the testis, prepubertal (15 dpp to 30 dpp) and pubertal (60 dpp to 75 dpp) male Sprague-Dawley rats were exposed to BPA (50 µg/kg bw/day), 17-β-estradiol (E2) (20 µg/kg bw/day) as a positive control, or to a combination of these compounds. For both periods of exposure, the rats were sacrificed and their testes were collected at 75 dpp. The histological analysis and the quantification of the gene expression of testis cell markers by RT-qPCR confirmed the complete spermatogenesis in all groups for both periods of exposure. However, our results suggest a deleterious effect of BPA on the blood-testis barrier in adults after pubertal exposure as BPA and BPA+E2 treatments induced a decrease in caveolin-1 and connexin-43 gene expression; which are proteins of the junctional complexes. As none of these effects were found after a prepubertal exposure, these results suggested the reversibility of BPA's effects. Caution must be taken when transposing this finding to humans and further studies are needed in this regard. However, from a regulatory perspective, this study emphasizes the importance of taking into account different periods of exposure, as they present different sensitivities to BPA exposure.

Wuzi-Yanzong prescription alleviates spermatogenesis disorder induced by heat stress dependent on Akt, NF-κB signaling pathway

Akt and nuclear factor kappa B (NF-κB) signaling pathways are involved in germ cell apoptosis and inflammation after testicular heat stress (THS). We observed that after THS induced by the exposure of rat testes to 43 °C for 20 min, their weight decreased, the fraction of apoptotic testicular germ cells significantly increased, and the proliferation of germ cells was inhibited. In addition, THS lowered serum testosterone (T) level, whereas the levels of follicle stimulating hormone and luteinizing hormone were not significantly changed. The ultrastructure of the seminiferous tubules became abnormal after THS, the structure of the blood-testis barrier (BTB) became loose, and the Sertoli cells showed a trend of differentiation. The level of phosphorylated Akt was reduced, whereas the amount of phosphorylated NF-κB p65 was augmented by THS. Wuzi-Yanzong (WZYZ), a classic Chinese medicine prescription for the treatment of male reproductive dysfunctions, alleviated the changes induced by THS. In order to determine the mechanism of action of WZYZ, we investigated how this preparation modulated the levels of T, androgen receptor (AR), erythropoietin (EPO), EPO receptor, and Tyro-3, Axl, and Mer (TAM) family of tyrosine kinase receptors. We found that WZYZ activated the Akt pathway, inhibited the Toll-like receptor/MyD88/NF-κB pathway, and repaired the structure of BTB by regulating the levels of T, AR, TAM receptors, and EPO. In conclusion, these results suggest that WZYZ activates the Akt pathway and inhibits the NF-κB pathway by acting on the upstream regulators, thereby improving spermatogenesis deficit induced by THS.

Responses and coping methods of different testicular cell types to heat stress: overview and perspectives

To facilitate temperature adjustments, the testicles are located outside the body cavity. In most mammals, the temperature of the testes is lower than the body temperature to ensure the normal progression of spermatogenesis. Rising temperatures affect spermatogenesis and eventually lead to a decline in male fertility or even infertility. However, the testes are composed of different cell types, including spermatogonial stem cells (SSCs), spermatocytes, spermatozoa, Leydig cells, and Sertoli cells, which have different cellular responses to heat stress. Recent studies have shown that using different drugs can relieve heat stress-induced reproductive damage by regulating different signaling pathways. Here, we review the mechanisms by which heat stress damages different cells in testes and possible treatments.

The inhibition of microtubule dynamics instability alters lipid homeostasis in TM4 Sertoli cells

Sertoli cells (SC) structurally support and transport nutrients to germ cells during spermatogenesis facilitated by an active cytoskeleton. Chemical perturbation of SC microtubule (MT) dynamics instability leads to premature germ cell exfoliation demonstrating that this process is essential for male fertility, yet the effects of MT damaging drugs on SC lipid metabolism have been less explored. The aim of this study was to advance our understanding of how adequate SC MT dynamicity is needed to finely tune lipid homeostasis. To elucidate the role of MT dynamics instability on the latter, we suppressed MT dynamicity by long-term exposures to 10 nM of nocodazole (NCZ) on TM4-SC cultures. Inhibition of MT dynamics instability affected the distribution of [³H] arachidonate on TM4-SC. Triacylglycerols (TAG) exhibited a higher proportion of the [³H] label, with significantly lower percentages in the mitochondrial phospholipid cardiolipin, and notably, also in phosphatidylethanolamine. A noteworthy and progressive accumulation of lipid droplets during the period of exposure to NCZ was accompanied by increased TAG levels but not cholesterol levels in TM4-SC. NCZ-exposed cells reduced their mitochondrial membrane potential and increased ROS production without triggering apoptosis, had a compromised autophagic flux, and lost their transferrin expression. Although SC morphology was preserved, the NCZ-exposed cells displayed alteration of the normal organization of microfilaments (f-actin) and intermediate filaments (vimentin). Our findings suggest that a preserved MT dynamicity is essential in the maintenance of lipid and fatty acids homeostasis in SC, and thus highlights a novel target in these cells for drugs that impair MT dynamicity.

Lycium barbarum Polysaccharide Ameliorates Heat-Stress-Induced Impairment of Primary Sertoli Cells and the Blood-Testis Barrier in Rat via Androgen Receptor and Akt Phosphorylation

Male infertility induced by heat stress has been attracting more and more attention. Heat stress not only causes apoptosis of spermatocytes but also has adverse effects on Sertoli cells, further damaging spermatogenesis. Lycium barbarum polysaccharide (LBP) is the main bioactive component of Lycium barbarum, which has a protective effect on male reproduction, but its mechanism is still unclear. In this study, our results proved that LBP blocked the inhibitory effect on the proliferation activity of Sertoli cells after heat stress, reversed the dedifferentiation of Sertoli cells induced by heat stress, and ameliorated the structural integrity of the blood-testis barrier. In addition, it increased the expression of the androgen receptor and activated Akt signaling pathway to resist heat-stress-induced injury of Sertoli cells.

Heat stress response of somatic cells in the testis

The testis is a temperature-sensitive organ that needs to be maintained 2-7 °C below core body temperature to ensure the production of normal sperm. Failure to maintain testicular temperature in mammals impairs spermatogenesis and leads to low sperm counts, poor sperm motility and abnormal sperm morphology in the ejaculate. This review discusses the recent knowledge on the response of testicular somatic cells to heat stress and, specifically, regarding the relevant contributions of heat, germ cell depletion and inflammatory reactions on the functions of Sertoli and Leydig cells. It also outlines mechanisms of testicular thermoregulation, as well as the thermogenic factors that impact testicular function.

Chronic stress affects tyrosine phosphorylated protein expression and secretion of male rat epididymis

Chronic stress (CS) is shown to decrease the semen quality with changed expression of tyrosine phosphorylated (TyrPho) proteins in testicular and seminal tissues. However, the alterations of such proteins and fluid contents in the epididymis, producing sperm maturation factors, have never been reported. Sixteen adult rats were randomly divided into 2 groups (n = 8). The control animals were not subjected to stressors whereas CS rats were immobilised within restraint cage (4 hr/day) before cold forced-water swimming (15 min/day) for 60 days. Corticosterone, testosterone, blood glucose level (BGL), malondialdehyde (MDA) and biochemical components in epididymal fluid were assayed. Expressions of heat shock protein 70 (HSP-70), androgen receptor (AR) and TyrPho protein were investigated in epididymal tissue and fluid. Significantly, CS increased the corticosterone and BGL but decreased testosterone and epididymal substance levels. MDA level in tail epididymal fluid and HSP-70 expression in both regions of epididymal tissues and fluids, except in head epididymal fluid of CS were increased. Epididymal tissues showed the decrease of AR expression. Presence and changes of many TyrPho proteins were observed in CS. In conclusion, CS could affect functional proteins particularly TyrPho in epididymis, resulted in low semen quality.

Amelioration of heat stress-induced damage to testes and sperm quality

Heat stress (HS) occurs when temperatures exceed a physiological range, overwhelming compensatory mechanisms. Most mammalian testes are ∼4-5 °C cooler than core body temperature. Systemic HS or localized warming of the testes affects all types of testicular cells, although germ cells are more sensitive than either Sertoli or Leydig cells. Increased testicular temperature has deleterious effects on sperm motility, morphology and fertility, with effects related to extent and duration of the increase. The major consequence of HS on testis is destruction of germ cells by apoptosis, with pachytene spermatocytes, spermatids and epididymal sperm being the most susceptible. In addition to the involvement of various transcription factors, HS triggers production of reactive oxygen species (ROS), which cause apoptosis of germ cells and DNA damage. Effects of HS on testes can be placed in three categories: testicular cells, sperm quality, and ability of sperm to fertilize oocytes and support development. Various substances have been given to animals, or added to semen, in attempts to ameliorate heat stress-induced damage to testes and sperm. They have been divided into various groups according to their composition or activity, as follows: amino acids, antibiotics, antioxidant cocktails, enzyme inhibitors, hormones, minerals, naturally produced substances, phenolic compounds, traditional herbal medicines, and vitamins. Herein, we summarized those substances according to their actions to mitigate HS' three main mechanisms: oxidative stress, germ cell apoptosis, and sperm quality deterioration and testicular damage. The most promising approaches are to use substances that overcome these mechanisms, namely reducing testicular oxidative stress, reducing or preventing apoptosis and promoting recovery of testicular tissue and restoring sperm quality. Although some of these products have considerable promise, further studies are needed to clarify their ability to preserve or restore fertility following HS; these may include more advanced sperm analysis techniques, e.g. sperm epigenome or proteome, or direct assessment of fertilization and development, including in vitro fertilization or breeding data (either natural service or artificial insemination).

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.

Acute heat-treatment disrupts inhibin-related protein production and gene expression in the adult rat testis

Heat reversibly disrupts spermatogenesis, but the effects on Sertoli cell (SC) function and inhibin/activin-related proteins are less well-defined. Adult rat testis weights decreased by 40% within 2 weeks after heat-treatment (43 °C, 15 min), due to loss of pachytene spermatocytes and round spermatids. Coincident effects were reduced SC nuclear volume at one week and >50% reduction in expression of several critical SC genes (Inha, Cld11, Gja1, Tjp1, Cldn3) by 2 weeks. Leydig cell steroidogenic enzymes, Cyp11a1, Hsd3b1, were also reduced. Activin gene expression was unaffected at this time, but expression of the activin-binding protein, follistatin (Fst), increased >2-fold. At 4-8 weeks, coincident with the recovery of spermatocytes and early spermatids, but progressive loss of elongated spermatids, most SC genes had recovered; however, testicular activin A was reduced and activin B increased. At 8 weeks, serum inhibin was decreased and, consequently, serum FSH increased. Crucially, germ cell damage was not associated with a significant inflammatory response. At 14 weeks, most testicular parameters had returned to normal, but testis weights remained slightly reduced. These data indicate that, following acute heat-treatment, expression of several key Sertoli and Leydig cell genes declined in parallel with the initial loss of meiotic germ cells, whereas activins were responsive to the subsequent loss of mature spermatids, leading to an increase in testicular activin B production relative to activin A.

Vitamin C mitigates heat damage by reducing oxidative stress, inducing HSP expression in TM4 Sertoli cells

Heat stress is a major stressor that can lead to male reproductive dysfunction. Sertoli cells play a crucial role in spermatogenesis by providing germ cells with structural and nutritional support, and contributing to blood-testis barrier formation. Vitamin C (Vc) is an antioxidant capable of neutralizing reactive oxygen species and preventing lipid peroxidation widely used because it is inexpensive and highly accessible. In the present study, we investigated the protective effect of Vc on TM4 cells following heat stress. Pretreatment with Vc could effectively inhibit apoptosis (p < 0.01), lipid peroxidation, and lactate dehydrogenase (LDH) activity. However, a significant increase in the malondialdehyde (MDA) level and LDH activity (p < 0.01) was observed in TM4 cells without Vc-pretreatment, in conjunction with vacuole degeneration and karyopyknosis. In addition, both the messenger RNA and protein levels of CryAB, Hsp27, Hsp70, and Hsp110 substantially increased in the 3 and 12 hr recovery groups (p < 0.01). Vc also prevented microtubule aggregation following heat stress. These results suggest that pretreatment with Vc-protected TM4 cells against heat stress by reducing the level of oxidative stress and inducing heat shock protein expression.

Suppression of SEMA6C promotes preantral follicles atresia with decreased cell junctions in mice ovaries

Mammalian oocytes go through a long and complex developmental process, while acquiring the competencies that are required for fertilization and embryogenesis. Recent studies revealed that the communication between oocytes and granulosa cells (GCs) is a critical process for female follicle development. In the current study, we aimed to study whether and how semaphorin 6C (Sema6c) regulated the cell junctions between oocytes and GCs in mice preantral follicles. The attenuation of SEMA6C expression by siRNA decreased the cell-cell junctions and accelerated follicle atresia in vitro. PI3K-AKT pathway was activated when SEMA6C expression was downregulated. And the LY294002, a PI3K inhibitor, could reverse the effect of low SEMA6C expression on cell junctions in preantral follicles. Our findings revealed that Sema6c was involved in follicle development, and the suppression of SEMA6C led to cell junction defection by activating the PI3K/AKT pathway, which might also provide valuable information for understanding premature ovarian failure and ovarian aging.

The effects of flutamide on cell-cell junctions in the testis, epididymis, and prostate

In this review, we summarize recent findings on the effect of the anti-androgen flutamide on cell-cell junctions in the male reproductive system. We outline developmental aspects of flutamide action on the testis, epididymis, and prostate, and describe changes in junction protein expression and organization of junctional complexes in the adult boar following prenatal and postnatal exposure. We also discuss findings on the mechanisms by which flutamide induces alterations in cell-cell junctions in reproductive tissues of adult males, with special emphasis on cytoplasmic effects. Based on the results from in vivo and in vitro studies in the rat, we propose that flutamide affects the expression of junction proteins and junction complex structure not only by inhibiting androgen receptor activity, but equally important by modulating protein kinase-dependent signaling in testicular cells. Additionally, results from studies on prostate cancer cell lines point to a role for the cellular molecular outfit in response to flutamide.

Effect of local scrotal heating on the expression of tight junction-associated molecule Occludin in boar testes

The aim of this study was to determine whether local scrotal heating (42°C, for 1 hr) had an effect on the expression of tight junction (TJ)-associated molecule Occludin in boar testes. Adult boars (Landrace, n = 6) were used and randomly divided into two groups (n = 3 each). Three boars were given local scrotal exposure to 42°C for approximately 1 h with a home-made electric blanket of controlled temperature as local scrotal heating group, the other three boars received no heat treatment and were left at standard room temperature as control group. After 6 hr, all boars were castrated and the testes were harvested. qRT-PCR, Western blotting and immunohistochemistry were used to explore the expression and localization of Occludin. qRT-PCR and Western blotting showed that the protein and mRNA levels of Occludin significantly decreased in local scrotal heating group as compared to the control. Furthermore, immunoreactivity staining of Occludin was localized at the sites of the blood-testis barrier (BTB) and formed an almost consecutive and strong immunoreactivity strand in the control, while Occludin was limited to Sertoli cells (SCs) and no obvious immunoreactivity strand was present in local scrotal heating group. These data indicated that local scrotal heating decreased the expression of TJ-associated molecule Occludin, which may be involved in heat-induced spermatogenesis damage.

Short poly-glutamine repeat in the androgen receptor in New World monkeys

The androgen receptor mediates various physiological and developmental functions and is highly conserved in mammals. Although great intraspecific length polymorphisms in poly glutamine (poly-Q) and poly glycine (poly-G) regions of the androgen receptor in humans, apes and several Old World monkeys have been reported, little is known about the characteristics of these regions in New World monkeys. In this study, we surveyed 17 species of New World monkeys and found length polymorphisms in these regions in three species (common squirrel monkeys, tufted capuchin monkeys and owl monkeys). We found that the poly-Q region in New World monkeys is relatively shorter than that in catarrhines (humans, apes and Old World monkeys). In addition, we observed that codon usage for poly-G region in New World monkeys is unique among primates. These results suggest that the length of polymorphic regions in androgen receptor genes have evolved uniquely in New World monkeys.

Expression of Selenoprotein Genes Is Affected by Heat Stress in IPEC-J2 Cells

The aim of this study was to explore the impacts of heat stress (HS) on expressions of selenoprotein genes in IPEC-J2 cells. Cells were cultured with 5 % CO2-humidified chamber at 37 °C until the cells grew to complete confluence and then exposed to a mild hyperthermia at 41.5 °C (HS) or 37 °C (control) for another 24 h, finally harvested for total RNA or protein extraction. Real-time quantitative PCRs (qPCRs) were performed to compare gene expression of 25 selenoprotein genes, 3 tight junction-related genes, and 10 inflammation-related genes. Protein expressions of heat shock protein 70 (Hsp70) and selenoprotein X and P (SelX and SelP) were also investigated by Western blot. The results showed that HS up-regulated (P < 0.05) Hsp70 and one tight junction-related gene [zonula occludens-1 (Zo-1)] in IPEC-J2 cells. At the same time, HS up-regulated (P < 0.05) 4 selenoprotein genes (Gpx3, Dio2, Selk, Sels) and three inflammation-related genes (Il-6, Icam-1, Tgf-β) and down-regulated (P < 0.05 or as indicated) six selenoprotein genes (Gpx2, Gpx6, Txnrd1, Selh, Selm, Selx) and three inflammation-related genes (Ifn-β, Mcp-1, Tnf-α) in the cells. HS also exhibited impacts on protein expressions, which up-regulated Hsp70, down-regulated SelX, and showed no effect on SelP in IPEC-J2 cells. Our results showed that HS affected the expression of inflammation-related genes and up-regulated gene and protein expressions of Hsp70. The changes of so many selenoprotein genes expression implied a potential link between selenoprotein genes and HS. Moreover, the results provided by this IPEC-J2 model may be used to further study the interactive mechanisms between selenoprotein function and potential intestinal damage induced by HS.

Changes in Levels of Seminal Nitric Oxide Synthase, Macrophage Migration Inhibitory Factor, Sperm DNA Integrity and Caspase-3 in Fertile Men after Scrotal Heat Stress

Background

This study observes changes in levels of seminal nitric oxide (NO), nitric oxide synthase (NOS), macrophage migration inhibitory factor (MIF), sperm DNA integrity, chromatin condensation and Caspase-3in adult healthy men after scrotal heat stress (SHS).

Methods

Exposure of the scrotum of 25 healthy male volunteers locally at 40–43°C SHS belt warming 40 min each day for successive 2 d per week. The course of SHS was continuously 3 months. Routine semen analysis, hypo-osmotic swelling (HOS) test, Aniline blue (AB) staining, HOS/AB and terminal deoxynucleotidyl transferase-mediated d UDP nick-end labeling (TUNEL) were carried out before, during and after SHS. Seminal NO and NOS contents were determined by nitrate reduction method. The activated Caspase-3 levels of spermatozoa and MIF in seminal plasma were measured by the enzyme-linked immunosorbent assay (ELISA) method. Statistical significance between mean values was determined using statistical ANOVA tests.

Results

The mean parameters of sperm concentration, motile and progressive motile sperm and normal morphological sperm were significantly decreased in groups during SHS 1, 2 and 3 months compared with those in groups of pre-SHS (P<0.001). Statistically significant differences of sperm DNA fragmentation, normal sperm membrane, and Caspase-3 activity as well as the level of NO, NOS and MIF in semen were observed between the groups before SHS and after SHS 3 months and the groups during SHS 1, 2 and 3 months (P<0.001). After three months of the SHS, various parameters recovered to the level before SHS. WBC in semen showed a positively significant correlation with the levels of NO, NOS, MIF and Caspase-3 activity. The percentage of abnormal sperm by using the test of HOS showed a positively significant correlation with that of HOS/AB.

Conclusions

The continuously constant SHS can impact the semen quality and sperm DNA and chromatin, which may be contributed to the high level of NO, NOS, MIF and Caspase-3 by SHS.

Acute heat stress induces differential gene expressions in the testes of a broiler-type strain of Taiwan country chickens

The expression of testicular genes following acute heat stress has been reported in layer-type roosters, but few similar studies have been conducted on broilers. This study investigated the effect of acute heat stress on the gene expression in the testes of a broiler-type strain of Taiwan country chickens. Roosters were subjected to acute heat stress (38°C) for 4 h, and then exposed to 25°C, with testes collected 0, 2, and 6 h after the cessation of heat stress, using non-heat-stressed roosters as controls (n = 3 roosters per group). The body temperature and respiratory rate increased significantly (p<0.05) during the heat stress. The numbers of apoptotic cells increased 2 h after the acute heat stress (79 ± 7 vs. 322 ± 192, control vs. heat stress; p<0.05), which was earlier than the time of increase in layer-type roosters. Based on a chicken 44 K oligo microarray, 163 genes were found to be expressed significantly different in the testes of the heat-stressed chickens from those of the controls, including genes involved in the response to stimulus, protein metabolism, signal transduction, cell adhesion, transcription, and apoptosis. The mRNA expressions of upregulated genes, including HSP25, HSP90AA1, HSPA2, and LPAR2, and of downregulated genes, including CDH5, CTNNA3, EHF, CIRBP, SLA, and NTF3, were confirmed through quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, numerous transcripts in the testes exhibited distinct expressions between the heat-stressed broiler-type and layer-type chickens. We concluded that the transcriptional responses of testes to acute heat stress may differ between the broiler-type and layer-type roosters. Whether the differential expression patterns associate with the heat-tolerance in the strains require a further exploration.

Effects of local testicular heat treatment on Leydig cell hyperplasia and testosterone biosynthesis in rat testes

Cryptorchidism or local testicular heat treatment induces reversible oligospermia or azoospermia in rodents and humans via increased germ cell apoptosis. Research in this field has concentrated on the impact of heat on spermatogenesis, with rather little attention paid to the molecular effects of heat treatment on Leydig cell function. In the present study, we investigated the effects of exposure to heat stress on the proliferative activity and testosterone biosynthesis of Leydig cells. We subjected adult rats to a single local testicular heat treatment of water at 43°C for 30min. The expression of Leydig cell-specific markers, such as cholesterol side-chain cleavage (P450SCC) and 3?-hydroxysteroid dehydrogenase, was evaluated by immunohistochemistry and western blot analysis. The proliferative activity of Leydig cells was detected by immunostaining with proliferation-associated markers, including Ki67, bromodeoxyuridine and phosphohistone-H3 (pHH3). The mRNA and protein levels of cell cycle proteins and testosterone synthesis-related enzymes were measured by real-time polymerase chain reaction and western blot analysis, respectively. The testes of heat-treated rats contained 50% more Leydig cells than those of control rats, indicating induction of Leydig cell hyperplasia by testicular heat treatment. Increased proliferative activity in Leydig cells, evidenced by enhanced expression of cell cycle proteins, was the main cause of Leydig cell hyperplasia. In addition, heat treatment reduced serum and testicular testosterone concentrations. Consistent with this finding, heat stress downregulated two enzymes required for testosterone biosynthesis, namely cytochrome P450, family 17 (CYP17) and steroidogenic acute regulatory protein, in Leydig cells. Together, the results suggest that testicular heat leads to Leydig cell hyperplasia and a reduction in testosterone biosynthesis in adult rat testes.

Musashi-1 maintains blood-testis barrier structure during spermatogenesis and regulates stress granule formation upon heat stress

Msi-1 knockdown disrupts blood-testis barrier structure and the continuous process of spermatogenesis. A role for Msi-1 in regulating Sertoli cell fate following heat-induced injury is noted.

In mouse testes, Musashi-1 (Msi-1) was predominantly expressed in the cytoplasm and nuclei of Sertoli cells. Here we demonstrate that knockdown of Msi-1 in Sertoli cells altered the levels and distribution of blood–testis barrier (BTB)-associated proteins. Moreover, Msi-1 knockdown in vivo disrupted BTB functional structure and spermatogenesis. In addition, we report a novel role of Msi-1 in regulating Sertoli cells survival following heat-induced injury. Endogenous Msi-1 protein in heat-treated Sertoli cells was recruited to stress granules. The formation of stress granules was considerably disrupted, and apoptosis was significantly up-regulated in Msi-1–knockdown Sertoli cells after heat treatment. p-ERK1/2 acted downstream of stress granule formation, and inhibition of p-ERK1/2 signaling triggered Sertoli cell apoptosis upon heat stress. In conclusion, we demonstrate that Msi-1 is critical for constructing a functional BTB structure and maintaining spermatogenesis. We also note a role for Msi-1 in regulating Sertoli cell fate following heat-induced injury, likely through the induction of stress granule formation and subsequent activation of p-ERK1/2 signaling.

Scrotal heat stress causes sperm chromatin damage and cysteinyl aspartate-spicific proteinases 3 changes in fertile men

PURPOSE

To observe changes in semen parameters, sperm DNA integrity, chromatin condensation and cysteinyl aspartate-spicific proteinases (Caspase-3) in adult healthy men after scrotal heat stress (SHS).

METHODS

The scrotums of 19 healthy male volunteers were exposed to the condition of 40-43 °C SHS belt warming 40 min each day for successive 2 days per week. The course of SHS was continuously 3 months. Routine semen analysis, hypo-osmotic swelling (HOS) test, eosin Y (EY) staining sperm HOS and chromatin dispersion (HOS/SCD) test, HOS and aniline blue (HOS/AB) staining test were carried out before, during and after SHS. The activated Caspase 3 levels of spermatozoa were determined with a microtiter plate reader.

RESULTS

The mean parameters of sperm concentration, motility and normal morphological sperm were significantly decreased in groups with sperm being collected during SHS 1, 2 and 3 months when compared with those in groups of pre-SHS (P < 0.01). Statistically significant differences of sperm DNA fragmentation, normal sperm membrane and vitality, and Caspase-3 activity were observed between the groups of before SHS and after SHS 3 months and the groups of during SHS 1, 2 and 3 months (P < 0.001). Three months the SHS stopped, various parameters recovered to the level before SHS. Abnormal sperm with HOS/AB and HOS/SCD showed a negatively significant correlation with normal sperm by HOS/EY test, and WBC in semen showed a positively significant correlation with Caspase-3 activity. The percentage of abnormal sperm by using the test of HOS/SCD showed a positively significant correlation with that of HOS/AB.

CONCLUSIONS

The continuously constant SHS can impact the semen quality, sperm DNA integrity, chromatin condensation and Caspase-3, and the combination of HOS plus AB test may simultaneously determine the integrity of membrane and chromatin condensation at the same spermatozoon.

Regulation of spermatogonial stem cell self-renewal and spermatocyte meiosis by Sertoli cell signaling

Spermatogenesis is a continuous and productive process supported by the self-renewal and differentiation of spermatogonial stem cells (SSCs), which arise from undifferentiated precursors known as gonocytes and are strictly controlled in a special 'niche' microenvironment in the seminiferous tubules. Sertoli cells, the only somatic cell type in the tubules, directly interact with SSCs to control their proliferation and differentiation through the secretion of specific factors. Spermatocyte meiosis is another key step of spermatogenesis, which is regulated by Sertoli cells on the luminal side of the blood-testis barrier through paracrine signaling. In this review, we mainly focus on the role of Sertoli cells in the regulation of SSC self-renewal and spermatocyte meiosis, with particular emphasis on paracrine and endocrine-mediated signaling pathways. Sertoli cell growth factors, such as glial cell line-derived neurotrophic factor (GDNF) and fibroblast growth factor 2 (FGF2), as well as Sertoli cell transcription factors, such as ETS variant 5 (ERM; also known as ETV5), nociceptin, neuregulin 1 (NRG1), and androgen receptor (AR), have been identified as the most important upstream factors that regulate SSC self-renewal and spermatocyte meiosis. Other transcription factors and signaling pathways (GDNF-RET-GFRA1 signaling, FGF2-MAP2K1 signaling, CXCL12-CXCR4 signaling, CCL9-CCR1 signaling, FSH-nociceptin/OPRL1, retinoic acid/FSH-NRG/ERBB4, and AR/RB-ARID4A/ARID4B) are also addressed.

Minireview: Steroid/nuclear receptor-regulated dynamics of occluding and anchoring junctions

A diverse set of physiological signals control intercellular interactions by regulating the structure and function of occluding junctions (tight junctions) and anchoring junctions (adherens junctions and desmosomes). These plasma membrane junctions are comprised of multiprotein complexes of transmembrane and cytoplasmic peripheral plasma membrane proteins. Evidence from many hormone-responsive tissues has shown that expression, modification, molecular interactions, stability, and localization of junctional complex-associated proteins can be targeted by nuclear hormone receptors and their ligands through transcriptional and nontranscriptional mechanisms. The focus of this minireview is to discuss molecular, cellular, and physiological studies that directly link nuclear receptor- and ligand-triggered signaling pathways to the regulation of occluding and anchoring junction dynamics.

Altered lipid homeostasis in Sertoli cells stressed by mild hyperthermia

Spermatogenesis is known to be vulnerable to temperature. Exposures of rat testis to moderate hyperthermia result in loss of germ cells with survival of Sertoli cells (SC). Because SC provide structural and metabolic support to germ cells, our aim was to test the hypothesis that these exposures affect SC functions, thus contributing to germ cell damage. In vivo, regularly repeated exposures (one of 15 min per day, once a day during 5 days) of rat testes to 43 °C led to accumulation of neutral lipids. This SC-specific lipid function took 1-2 weeks after the last of these exposures to be maximal. In cultured SC, similar daily exposures for 15 min to 43 °C resulted in significant increase in triacylglycerol levels and accumulation of lipid droplets. After incubations with [3H]arachidonate, the labeling of cardiolipin decreased more than that of other lipid classes. Another specifically mitochondrial lipid metabolic function, fatty acid oxidation, also declined. These lipid changes suggested that temperature affects SC mitochondrial physiology, which was confirmed by significantly increased degrees of membrane depolarization and ROS production. This concurred with reduced expression of two SC-specific proteins, transferrin, and Wilms' Tumor 1 protein, markers of SC secretion and differentiation functions, respectively, and with an intense SC cytoskeletal perturbation, evident by loss of microtubule network (α-tubulin) and microfilament (f-actin) organization. Albeit temporary and potentially reversible, hyperthermia-induced SC structural and metabolic alterations may be long-lasting and/or extensive enough to respond for the decreased survival of the germ cells they normally foster.

Ligand-dependent stabilization of androgen receptor in a novel mouse ST38c Sertoli cell line

Mature Sertoli cells (SC) are critical mediators of androgen regulation of spermatogenesis, via the androgen receptor (AR) signaling. Available immortalized SC lines loose AR expression or androgen responsiveness, hampering the study of endogenous AR regulation in SC. We have established and characterized a novel clonal mouse immortalized SC line, ST38c. These cells express some SC specific genes (sox9, wt1, tjp1, clu, abp, inhbb), but not fshr, yet more importantly, maintain substantial expression of endogenous AR as determined by PCR, immunocytochemistry, testosterone binding assays and Western blots. Microarrays allowed identification of some (146) but not all (rhox5, spinlw1), androgen-dependent, SC expressed target genes. Quantitative Real-Time PCR validated regulation of five up-regulated and two down-regulated genes. We show that AR undergoes androgen-dependent transcriptional activation as well as agonist-dependent posttranslational stabilization in ST38c cells. This cell line constitutes a useful experimental tool for future investigations on the molecular and cellular mechanisms of androgen receptor signaling in SC function.

Interleukin-6 disrupts blood-testis barrier through inhibiting protein degradation or activating phosphorylated ERK in Sertoli cells

It has been recently ascribed to several inflammatory cytokines (i.e. TGF-β3, TNF-α, and IL-1) a functional role in regulating Sertoli cell blood-testis barrier (BTB) dynamics. In the testis, IL-6 inhibits meiotic DNA synthesis during the seminiferous epithelium cycle, reduces sperm motility and influences the secretion of transferrin and inhibin B by Sertoli cells. Also, it has been shown that IL-6 affects tight junction permeability in Sertoli cells, but, little is known about its role in regulating the BTB. The aim of this study was to investigate the molecular mechanisms by which IL-6 affects BTB dynamics. We show that IL-6 perturbs the integrity of the BTB, and alters the normal localization and steady-state levels of BTB integral membrane proteins. We demonstrated that IL-6 regulates the BTB by inhibiting the degradation of BTB constitutive proteins and activating ERK-MAPK pathways. Our results provide mechanistic insight into the roles of IL-6 in regulating BTB dynamics.

Wnt/β-catenin signaling regulates follicular development by modulating the expression of Foxo3a signaling components

Wnt signaling is an evolutionarily conserved pathway that regulates cell proliferation, differentiation and apoptosis. To investigate the possible role of Wnt signaling in the regulation of ovarian follicular development, secondary follicles were isolated and cultured in vitro in the presence or absence of its activator (LiCl or Wnt3a) or inhibitor (IWR-1). We have demonstrated that activation of β-catenin signals by activators dramatically suppressed follicular development by increasing granulosa cell apoptosis and inhibiting follicle steroidogenesis. In contrast, inhibition of Wnt signaling by IWR-1 was observed with better developed follicles and increased steroidogenesis. Further studies have shown that the transcription factor Forkhead box O3a (Foxo3a) and its downstream target molecules were modulated by the activators or the inhibitor. These findings provide evidence that Wnt signaling might negatively regulate follicular development potentially through Foxo3a signaling components.

Heat shock protein 32/heme oxygenase-1 protects mouse Sertoli cells from hyperthermia-induced apoptosis by CO activation of sGC signalling pathways

Heat shock protein 32 (Hsp32)/heme oxygenase-1 (HO-1) may be a key enzyme for the protection of cells against stress. Its anti-apoptotic effect has been attributed to its product, carbon monoxide (CO), in many types of cells. However, whether its anti-apoptotic mechanism plays a role in Sertoli cells (SCs) is not yet clear. We hypothesise that Hsp32/HO-1 and CO generated from it provide survival advantages in SCs by preventing apoptosis under heat exposure. After treatment of cultured SCs with hyperthermia and/or Hsp32/HO-1 activater hemin, apoptosis was measured valuated by annexin V-FITC and caspase-3 activation. We have also analysed the Hsp32/HO-1-derived CO content of cultured media and cyclic guanosine monophosphate (cGMP) production by enzyme-linked immunosorbent assay (ELISA). Hyperthermia induced SCs apoptosis, while preincubation with hemin suppressed SC hyperthermia-induced apoptosis. Hyperthermia and/or hemin increase Hsp32/HO-1 gene expression and the production of CO, which, in turn, stimulates the generation of cGMP. The results suggest that Hsp32/HO-1 is a protective factor in heat-stressed SCs, and that CO generated from Hsp32/HO-1 is involved in the anti-apoptotic pathway.

Eicosapentaenoic acid enhances heat stress-impaired intestinal epithelial barrier function in Caco-2 cells

Objective

Dysfunction of the intestinal epithelial tight junction (TJ) barrier is known to have an important etiologic role in the pathophysiology of heat stroke. N-3 polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), play a role in maintaining and protecting the TJ structure and function. This study is aimed at investigating whether n-3 PUFAs could alleviate heat stress-induced dysfunction of intestinal tight junction.

Methods

Human intestinal epithelial Caco-2 cells were pre-incubated with EPA, DHA or arachidonic acid (AA) and then exposed to heat stress. Transepithelial electrical resistance (TEER) and Horseradish Peroxidase (HRP) permeability were measured to analyze barrier integrity. Levels of TJ proteins, including occludin, ZO-1 and claudin-2, were analyzed by Western blot and localized by immunofluorescence microscopy. Messenger RNA levels were determined by quantitative real time polymerase chain reaction (Q-PCR). TJ morphology was observed by transmission electron microscopy.

Results

EPA effectively attenuated the decrease in TEER and impairment of intestinal permeability in HRP flux induced by heat exposure. EPA significantly elevated the expression of occludin and ZO-1, while DHA was less effective and AA was not at all effective. The distortion and redistribution of TJ proteins, and disruption of morphology were also effectively prevented by pretreatment with EPA.

Conclusion

This study indicates for the first time that EPA is more potent than DHA in protecting against heat-induced permeability dysfunction and epithelial barrier damage of tight junction.

Heat stress response of male germ cells

The vast majority of mammalian testes are located outside the body cavity for proper thermoregulation. Heat has an adverse effect on mammalian spermatogenesis and eventually leads to sub- or infertility. Recent studies have provided insights into the molecular response of male germ cells to high temperatures. Here, we review the effects of heat on male germ cells and discuss the mechanisms underlying germ cell loss and impairment. We also discuss the role of translational control in male germ cells as a potential protective mechanism against heat-induced germ cell apoptosis.

Nuclear export factor 3 is involved in regulating the expression of TGF-β3 in an mRNA export activity-independent manner in mouse Sertoli cells

The NXF (nuclear export factor) family members are implicated in the transport of mRNA from the nucleus to the cytoplasm. Recently, some members of the NXF family have been reported to play divergent functional roles, such as post-transcriptional regulation, translational control, regulation of mRNA stability and trafficking. However, little is known about the roles of NXF3 in spermatogenesis. In the present study, we found that mouse NXF3, specifically expressed in principal cells in segment II of the caput epididymis, as well as Sertoli cells in the mouse testis, was required to mediate TGF-β (transforming growth factor β)-induced down-regulation of Tgfb3/TGF-β3 mRNA expression and protein secretion in Sertoli cells. In addition, NXF3 was also involved in TGF-β-induced transcriptional regulation of other genes associated with Sertoli cell maturation and the restructuring of the Sertoli cell BTB (blood-testis barrier), such as Gata1 (GATA-binding protein 1), Wt1 (Wilms's tumour homologue 1), Cldn11 (claudin11) and Cdkn1a (cyclin-dependent kinase inhibitor 1A or p21(Cip1)). The transcriptional regulation of NXF3 was mediated through physical interaction with STRAP (serine/threonine kinase receptor-associated protein), where NXF3 inhibited the complex formation among Smad7, STRAP and activated type I TGF-β receptor. Taken together, our data provide mechanistic insights into the roles of NXF3 in TGF-β-mediated expression of Tgfb3 and other genes. NXF3 may be implicated in Sertoli cell maturation and the extensive restructuring of the Sertoli cell BTB.

Upregulation of heat shock protein 32 in Sertoli cells alleviates the impairments caused by heat shock-induced apoptosis in mouse testis

Heat stress results in apoptosis in testicular germ cells. A small heat shock protein (hsp), hsp32, is induced by heat stress in the testis, but little is known about its definitive function in physiological processes. To clarify the underlying role of hsp32, hsp32 expression and related signals in the heat shock pathway were analysed in mouse testes and Sertoli cells after heat stress in vivo and in vitro; meanwhile, expression of hsp32 was silenced only in the Sertoli cells using three different small interfering RNAs (siRNAs) to further verify the functional role of hsp32 in Sertoli cells, and hsp32-derived carbon monoxide (CO) contents in cultured media were analysed to clarify whether hsp32-derived CO involve in the apoptosis regulation mechanisms. The results from the in vivo experiment showed that the high expression levels of hsp32 (P < 0.05) were observed whether chronic, moderate or acute, transient heat exposure. The in vitro experiment showed that acute, transient heat exposure resulted in increases in Sertoli cells apoptosis (P < 0.01), the expression of hsp32 and caspase-3 activity; hsp32-siRNA knockdown of hsp32 expression resulted in upregulated apoptosis (P < 0.01) and caspase-3 activity (P < 0.01) in the Sertoli cells and hyperthermia increases CO (P < 0.01) release by Sertoli cells. The results suggested that upregulating hsp32 in Sertoli cells inhibits caspase-3 activity and alleviates heat-induced impairments in mouse testis; hsp32-derived CO may involve in the regulation mechanism.

Protective effects of ginsenosides against Bisphenol A-induced cytotoxicity in 15P-1 Sertoli cells via extracellular signal-regulated kinase 1/2 signalling and antioxidant mechanisms

Numerous studies have demonstrated that Bisphenol A (BPA) can cause reproductive toxicity. Ginseng has wide range of pharmacological actions and, more importantly, has proven its worth with respect to reproductive function in several reports. We have suggested that ginsenosides, the main active components of ginseng, may protect against BPA-induced cell damage. Therefore, an in vitro culture model of 15P-1 Sertoli cells was employed to investigate whether ginsenosides have protective effects on BPA-stimulated 15P-1 Sertoli cells. The results revealed that ginsenosides (75 μg/ml) significantly inhibited BPA-induced decreases in cell viability and increases in apoptosis. Immunofluorescence staining showed that BPA exposure-induced collapse of vimentin intermediate filaments was prevented by the application of ginsenosides. Ginsenosides also inhibited extracellular signal-regulated kinase (ERK1/2) phosphorylation and BPA-induced alterations of Bcl-2 and Bax protein expression in 15P-1 Sertoli cells. Furthermore, the alterations of T-AOC, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione and malondialdehyde levels in BPA-stimulated cells were partially prevented with pre-treatment with ginsenosides. Taken together, these results suggest that ginsenosides have protective effects against BPA-induced cell damage and that these effects are mediated by preventing ERK1/2 phosphorylation and through the enhancement of cellular antioxidant capacity. Ginsenosides may therefore be beneficial in the prevention of environmental BPA-induced, reproduction-related toxicity.