SMAD signaling pathway is disrupted by BPA via the AMH receptor in bovine granulosa cells†

Significant events that determine oocyte competence occur during follicular growth and oocyte maturation. The anti-Mullerian hormone, a positive predictor of fertility, has been shown to be affected by exposure to endocrine disrupting compounds, such as bisphenol A and S. However, the interaction between bisphenols and SMAD proteins, mediators of the anti-Mullerian hormone pathway, has not yet been elucidated. AMH receptor (AMHRII) and downstream SMAD expression was investigated in bovine granulosa cells treated with bisphenol A, bisphenol S, and then competitively with the anti-Mullerian hormone. Here, we show that 24-h bisphenol A exposure in granulosa cells significantly increased SMAD1, SMAD4, and SMAD5 mRNA expression. No significant changes were observed in AMHRII or SMADs protein expression after 24-h treatment. Following 12-h treatments with bisphenol A (alone or with the anti-Mullerian hormone), a significant increase in SMAD1 and SMAD4 mRNA expression was observed, while a significant decrease in SMAD1 and phosphorylated SMAD1 was detected at the protein level. To establish a functional link between bisphenols and the anti-Mullerian hormone signaling pathway, antisense oligonucleotides were utilized to suppress AMHRII expression with or without bisphenol exposure. Initially, transfection conditions were optimized and validated with a 70% knockdown achieved. Our findings show that bisphenol S exerts its effects independently of the anti-Mullerian hormone receptor, while bisphenol A may act directly through the anti-Mullerian hormone signaling pathway providing a potential mechanism by which bisphenols may exert their actions to disrupt follicular development and decrease oocyte competence.

Quality of fresh and cryopreserved bovine sperm is reduced by BPA and BPF exposure

Bisphenol A (BPA) is an endocrine disrupting compound, used as the key monomer of polycarbonate plastics and epoxy resins. BPA has been detected in both humans and farm animals and has been correlated with decreased sperm counts and motility. BPS and BPF are structural analogs of BPA and are increasingly being used in manufacturing as BPA substitutes. In this study we aim to assess the direct outcomes of BPA, BPS and BPF exposure on bovine sperm parameters in vitro to elucidate how they affect sperm quality and fertilization potential, and to assess whether BPS and/or BPF are less harmful than BPA. Sperm from three or more bulls was obtained from either fresh samples or cryopreserved straws and exposed to 0.05 mg/mL of BPA, BPS and BPF in vitro. After 4h incubation, motility, capacitation, apoptosis/necrosis, and mitochondrial membrane potential levels were measured by CASA or computational flow cytometry. Results showed that BPA exposure significantly reduced both fresh and cryopreserved sperm motility, capacitation, viability and mitochondrial membrane potential levels. Furthermore, BPF significantly decreased motility, capacitation and mitochondrial membrane potential in cryopreserved sperm only. BPS did not have any significant effects on any of the parameters measured. Our results suggest that BPA is the most harmful to sperm, while BPF is toxic under certain conditions, and BPS seems to be the least detrimental. Overall, this study provides an understanding of how the ubiquitous environmental chemicals, bisphenols, may impact male fertility even after ejaculation.

Sperm capacitation and transcripts levels are altered by in vitro THC exposure

BACKGROUND

Delta-9-tetrahydrocannabinol (THC) is the primary phytocannabinoid responsible for the psychoactive properties of cannabis and is known to interact with the endocannabinoid system, which is functionally present in the male reproductive system. Since cannabis consumption is the highest among reproductive aged males, the current study aimed to further investigate the effects of THC exposure to phenotypical, physiological, and molecular parameters in sperm. Bull sperm of known fertility were used as a translational model for human sperm and subjected to in vitro treatment with physiologically relevant experimental doses of THC. Sperm parameters, capacitation, apoptosis, and transcript levels were evaluated following treatment.

RESULTS

Motility, morphology, and viability of bovine sperm was unaltered from THC exposure. However, 0.32µM of THC caused an increased proportion of capacitating sperm (p < 0.05) compared to control and vehicle group sperm. Transcriptome analysis revealed that 39 genes were found to be differentially expressed by 0.032µM THC exposure, 196 genes were differentially expressed by 0.32µM THC exposure, and 33 genes were differentially expressed by 3.2µM THC. Secondary analysis reveals pathways involving development, nucleosomes, ribosomes and translation, and cellular metabolism to be significantly enriched.

CONCLUSION

Phytocannabinoid exposure to sperm may adversely affect sperm function by stimulating premature capacitation. These findings also show for the first time that spermatozoal transcripts may be altered by THC exposure. These results add to previous research demonstrating the molecular effects of cannabinoids on sperm and warrant further research into the effects of cannabis on male fertility.

Glucocorticoids, Stress and Delta-9 Tetrahydrocannabinol (THC) during Early Embryonic Development

Elevated molecular stress in women is known to have negative impacts on the reproductive development of oocytes and the embryos prior to implantation. In recent years, the prevalence of cannabis use among women of reproductive age has risen due to its ability to relieve psychological stress and nausea, which are mediated by its psychoactive component, ∆-9-tetrahydrocannabinol (THC). Although cannabis is the most popular recreational drug of the 21st century, much is unknown about its influence on molecular stress in reproductive tissues. The current literature has demonstrated that THC causes dose- and time-dependent alterations in glucocorticoid signaling, which have the potential to compromise morphology, development, and quality of oocytes and embryos. However, there are inconsistencies across studies regarding the mechanisms for THC-dependent changes in stress hormones and how either compounds may drive or arrest development. Factors such as variability between animal models, physiologically relevant doses, and undiscovered downstream gene targets of both glucocorticoids and THC could account for such inconsistencies. This review evaluates the results of studies which have investigated the effects of glucocorticoids on reproductive development and how THC may alter stress signaling in relevant tissues.

Cascades of transcriptional induction during human lymphocyte activation

Lymphocyte activation is known to be associated with the induction of genes implicated in cytokine signaling and cellular proliferation. High-density microarrays offer the means to monitor global cellular expression profiles, temporal relationships between classes of transcripts, and alterations associated with human disease or immunosuppression. We sought to determine whether microarray analysis would accurately reflect the normal pattern of gene expression following human T cell activation, and whether the complex expression patterns identified could be analyzed to produce a functional profile of lymphocyte activation. We examined a time course of sequential expression profiles for 6,800 cellular transcripts in human lymphocytes activated with concanavalin A. Expression patterns were grouped using clustering analysis and validated using Northern blotting. Genes known to be induced following T cell activation were accurately identified, and the qualitative patterns of gene expression were well correlated between Northern and microarray analyses. Quantitative differences in gene expression levels were less well correlated between these two techniques. Expression profile analysis revealed the sequential induction of groups of functionally similar genes, whose temporal coregulation underscores known cellular events during T cell activation. This functional "fingerprint" of lymphocyte activation may prove useful for comparisons of lymphocyte responses under experimental conditions and in disease states.

The Wilms tumor suppressor WT1 encodes a transcriptional activator of amphiregulin

WT1 encodes a zinc finger transcription factor implicated in kidney differentiation and tumorigenesis. In reporter assays, WT1 represses transcription from GC- and TC-rich promoters, but its physiological targets remain uncertain. We used hybridization to high-density oligonucleotide arrays to search for native genes whose expression is altered following inducible expression of WT1. The major target of WT1 was amphiregulin, a member of the epidermal growth factor family. The WT1(-KTS) isoform binds directly to the amphiregulin promoter, resulting in potent transcriptional activation. The in vivo expression profile of amphiregulin during fetal kidney development mirrors the highly specific pattern of WT1 itself, and recombinant Amphiregulin stimulates epithelial branching in organ cultures of embryonic mouse kidney. These observations suggest a model for WT1 as a transcriptional regulator during kidney differentiation.

Induction of GADD45 and JNK/SAPK-dependent apoptosis following inducible expression of BRCA1

The breast cancer susceptibility gene BRCA1 encodes a protein implicated in the cellular response to DNA damage, with postulated roles in homologous recombination as well as transcriptional regulation. To identify downstream target genes, we established cell lines with tightly regulated inducible expression of BRCA1. High-density oligonucleotide arrays were used to analyze gene expression profiles at various times following BRCA1 induction. A major BRCA1 target is the DNA damage-responsive gene GADD45. Induction of BRCA1 triggers apoptosis through activation of c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK), a signaling pathway potentially linked to GADD45 gene family members. The p53-independent induction of GADD45 by BRCA1 and its activation of JNK/SAPK suggest a pathway for BRCA1-induced apoptosis.