Project description:In this study, chromatin immunoprecipitated sequencing was done for testis specific histone variants of H2B and H2A, TH2B and TH2A to understand the epigenomics of these retained histones, using murine caudal sperm.Our in silico analysis has attributed a myriad of novel functions to sperm retained TH2B with respect to embryo development and spermatogenesis.Also, based on genomic regions, TH2B was observed to be associated with spindle assembly and various meiosis-specific genes, which is an important finding as TH2A/TH2B DKO mice have been reported to have defective cohesin release.We also observed a degree of evolutionary conservation between the TH2B-DNA linkage across human and mouse.This overlap included genes important for embryogenesis. Most importantly, heterogeneity in the epigenetic landscape of TH2A and TH2B was seen which is intriguing as TH2B and TH2A are well reported to be present in the same nucleosomes to promote open chromatin. Additionally, unlike TH2B, TH2A was enriched on the mitochondrial chromosome. We presume that TH2A is associated with mitochondrial DNA inserted in the nuclear DNA and this observation needs further validation.. A comprehensive analysis of these observations indicates novel functions for the sperm retained TH2B and TH2A.
Project description:Current human reproductive risk assessment methods rely on semen and serum hormone analyses, which are not easily comparable to the histopathological endpoints and mating studies used in animal testing. Because of these limitations, there is a need to develop universal evaluations that reliably reflect male reproductive function. We hypothesized that toxicant-induced testicular injury can be detected in sperm using mRNA transcripts as indicators of insult. To test this, we exposed adult male Fischer 344 rats to low doses of model testicular toxicants and classically characterized the testicular injury while simultaneously evaluating sperm mRNA transcripts from the same animals. Overall, this study aimed to: 1) identify sperm transcripts altered after exposure to the model testicular toxicant, 2,5-hexanedione (HD) using microarrays; 2) expand on the HD-induced transcript changes in a comprehensive time course experiment using qRT-PCR arrays; and 3) test these injury indicators after exposure to another model testicular toxicant, carbendazim (CBZ). Microarray analysis of HD-treated adult Fischer 344 rats identified 128 altered sperm mRNA transcripts when compared to control using linear models of microarray analysis (q < 0.05). All transcript alterations disappeared after 3 months of post-exposure recovery. In the time course experiment, time-dependent alterations were observed for 12 candidate transcripts selected from the microarray data based upon fold change and biological relevance, and 8 of these transcripts remained significantly altered after the 3-month recovery period (p < 0.05). In the last experiment, 8 candidate transcripts changed after exposure to CBZ (p < 0.05). The two testicular toxicants produced distinct molecular signatures with only 4 overlapping transcripts between them, each occurring in opposite directions. Overall, these results suggest that sperm mRNA transcripts are indicators of low dose toxicant-induced testicular injury in the rat. Rats were exposed to sub-chronic low doses of the Sertoli cell toxicant 2,5-hexanedione (HD) or water (control for HD) for 3 months. Some rats in each group underwent 3 months of post-exposure recovery.
Project description:Current human reproductive risk assessment methods rely on semen and serum hormone analyses, which are not easily comparable to the histopathological endpoints and mating studies used in animal testing. Because of these limitations, there is a need to develop universal evaluations that reliably reflect male reproductive function. We hypothesized that toxicant-induced testicular injury can be detected in sperm using mRNA transcripts as indicators of insult. To test this, we exposed adult male Fischer 344 rats to low doses of model testicular toxicants and classically characterized the testicular injury while simultaneously evaluating sperm mRNA transcripts from the same animals. Overall, this study aimed to: 1) identify sperm transcripts altered after exposure to the model testicular toxicant, 2,5-hexanedione (HD) using microarrays; 2) expand on the HD-induced transcript changes in a comprehensive time course experiment using qRT-PCR arrays; and 3) test these injury indicators after exposure to another model testicular toxicant, carbendazim (CBZ). Microarray analysis of HD-treated adult Fischer 344 rats identified 128 altered sperm mRNA transcripts when compared to control using linear models of microarray analysis (q < 0.05). All transcript alterations disappeared after 3 months of post-exposure recovery. In the time course experiment, time-dependent alterations were observed for 12 candidate transcripts selected from the microarray data based upon fold change and biological relevance, and 8 of these transcripts remained significantly altered after the 3-month recovery period (p < 0.05). In the last experiment, 8 candidate transcripts changed after exposure to CBZ (p < 0.05). The two testicular toxicants produced distinct molecular signatures with only 4 overlapping transcripts between them, each occurring in opposite directions. Overall, these results suggest that sperm mRNA transcripts are indicators of low dose toxicant-induced testicular injury in the rat.
Project description:43 biopsies were obtained from subfertile/infertile patients undergoing testicular sperm extraction (TESE) as part of their treatment. Labelled cDNAs were compared to a reference normal testis RNA (Ambion).
Project description:Expression of key transcription factors Klf4, Oct3/4, Sox2, and c-Myc (KOSM) in embryonic stem cells can reprogram somatic cells into pluripotent cells. We found that two histone variants, TH2A and TH2B, and histone chaperone Npm enhance the KOSM-dependent generation of induced pluripotent cells (iPSCs) and produce iPSCs only with Klf4 and Oct3/4. To identify directly affected genes by these histone variants during reprogramming, we carried out gene expression profiling of MEFs overexpressing TH2A/TH2B/Npm and TH2A/TH2B deficient MEFs after infection with retroviruses expressing KOSM. A total of 21 Affymetrix Mouse Gene ST array were done for mRNA expression profiling of ES cells, iPS cells induced by Klf4, Oct4, Sox2, and c-Myc (KOSM) or Klf4, Oct4, Th2a, Th2b, and p-Npm (KOBAN), wild-type MEFs infected with retrovirus vectors expressing KOSM, KOSMBAN, or empty vector and Th2a/Th2b-deficient MEFs infected with retrovirus vector expressing KOSM.
Project description:Expression of key transcription factors Klf4, Oct3/4, Sox2, and c-Myc (KOSM) in embryonic stem cells can reprogram somatic cells into pluripotent cells. We found that two histone variants, TH2A and TH2B, and histone chaperone Npm enhance the KOSM-dependent generation of induced pluripotent cells (iPSCs) and produce iPSCs only with Klf4 and Oct3/4. To identify directly affected genes by these histone variants during reprogramming, we carried out gene expression profiling of MEFs overexpressing TH2A/TH2B/Npm and TH2A/TH2B deficient MEFs after infection with retroviruses expressing KOSM.
Project description:Supplementation with high doses of folic acid, an important mediator of one-carbon transfers for DNA methylation, is used clinically to improve sperm parameters in infertile men. We recently detected an unexpected loss of DNA methylation in the sperm of idiopathic infertile men after 6 months of daily supplementation with 5mg folic acid (>10× the daily recommended intake-DRI), exacerbated in men homozygous for a common variant in the gene encoding an important enzyme in folate metabolism, methylenetetrahydrofolate reductase (MTHFR 677C>T). To investigate the epigenomic impact and mechanism underlying effects of folic acid on male germ cells, wildtype and heterozygote mice for a targeted inactivation of the Mthfr gene were fed high-dose folic acid (10× the DRI) or control diets for six months. No changes were detected in general health, sperm counts or methylation of imprinted genes. Reduced representation bisulfite sequencing revealed sperm DNA hypomethylation in Mthfr+/- mice on the 10× diets. Wildtype mice demonstrated sperm hypomethylation only with a very high dose (20×) of folic acid for 12 months. Testicular MTHFR protein levels decreased significantly in wildtype mice on the 20× diet but not in those on the 10× diet, suggesting a possible role for MTHFR deficiency in sperm DNA hypomethylation. In-depth analysis of the folic acid-exposed sperm DNA methylome suggested mouse/human susceptibility of sequences with potential importance to germ cell and embryo development. Our data provide evidence for a similar cross-species response to high dose folic acid supplementation, of sperm DNA hypomethylation, and implicate MTHFR downregulation as a possible mechanism.
Project description:RNAs present in mature mammalian sperm are delivered to the zygote at fertilization, where they have the potential to affect early development. The biogenesis of the small RNA payload of mature sperm is therefore of great interest, as it may be a target of signaling pathways linking paternal conditions to offspring phenotype. Recent studies have suggested the surprising hypothesis that the small RNA payload carried by mature sperm may include RNAs that were not synthesized during testicular spermatogenesis, but that are instead delivered to sperm during the process of post-testicular maturation in the epididymis. To further test this hypothesis, we characterized small RNA dynamics during testicular and post-testicular germ cell maturation in mice, confirming and extending prior observations that testicular germ cell populations carry extremely low levels of tRNA fragments (tRFs), which only become highly abundant only after sperm have entered the epididymis. We examined the sperm RNA repertoire in greater detail, finding that the majority of 5’ tRNA fragments carry a 2’-3’ cyclic phosphate at their 3’ end, pointing to a role for RNaseA or T-family nucleases in tRNA cleavage in the male reproductive tract. The process of small RNA delivery to sperm can be recapitulated in vitro, as caput epididymosomes deliver small RNAs including tRFs and microRNAs to mature testicular spermatozoa. Finally, to definitively identify the tissue of origin for small RNAs in sperm, we carried out tissue-specific metabolic labeling of RNAs in intact mice, finding that mature sperm carry small RNAs that were originally synthesized in the somatic cells of the epididymis. Taken together, our data demonstrates that soma-germline small RNA transfer occurs in male mammals, most likely via vesicular transport from the epididymis to maturing sperm.
Project description:Testicular toxicity is one of the frequent adverse effects of cancer chemotherapy and the problem is that there is no effective biomarker. To find effective biomarkers, we focused on epigenetic mechanisms of male germline. Therefore, our study investigated the DNA methylation status of male germline under the testicular toxicity induced by doxorubicin(DXR), a widely used anticancer agent. We established mouse models of initial stage of testicular toxicity and testicular pre-toxicity by administrating 0.2 mg/kg and 0.02 mg/kg of DXR twice a week for 5 weeks. Western blotting analysis revealed the protein expression levels of DNA methyltransferases DNMT3a and DNMT3b were decreased in both the DXR administration groups. Consistently, comprehensive DNA methylation analysis of sperm DNA using MBD-seq revealed that the majority of methylation changes induced by DXR administration were hypomethylation. This study showed the possibility of early diagnosis of testicular toxicity by examining DNA methylation status of sperm.
Project description:We carried out whole genome bisulfite sequencing in seven purified sperm populations, including primary spermatocytes, early and late round spermatids, and mature sperm isolated from the caput, corpus, and cauda epididiymis, and from the vas deferens.