Project description:Spermatogenesis is precisely controlled by complex gene expression programs. During mammalian male germ cell development, a crucial feature is the repression of transcription before spermatid elongation. Previously, we discovered that RNA-binding protein EWSR1 plays an important role in meiotic recombination and is highly expressed in late meiotic cells and post-meiotic cells. Here, we used a Ewsr1 pachytene stage-specific knockout mouse model to study its roles at late meiotic prophase I and in spermatozoa maturation. We show that loss of EWSR1 at this stage does not affect proper meiosis completion, but the developing germ cells exhibit defects in spermatid elongation and chromocenter formation. In the Ewsr1 conditional knockout testes, expression of many genes regulating spermatid differentiation is impaired, suggesting that EWSR1 may play important role in regulation of spermiogenesis related mRNA synthesis and spermatid differentiation.
Project description:Taf7l (a paralogue of Taf7) and Trf2 (a TBP-related protein) are components of the core promoter complex required for gene/tissue-specific transcription of protein-coding genes by RNA polymerase II. Previous studies reported that Taf7l knockout mice exhibit structurally abnormal sperm, reduced sperm count, weakened motility and compromised fertility. Here we find that continued backcrossing of Taf7l-/Y mice from N5 to N9 produced KO males that are essentially sterile. Genome-wide expression profiling by mRNA-seq analysis of wild type (WT) and Taf7l-/Y (KO) testes revealed that Taf7l ablation impairs the expression of many post-meiotic spermatogenic specific as well as metabolic genes. Importantly, histological analysis of testes revealed that Taf7l-/Y mice develop post-meiotic arrest at the first stage of spermiogenesis, phenotypically similar to Trf2-/- mice, but distinct from Taf4b-/- mice. Indeed, we find that Taf7l and Trf2 co-regulate post-meiotic genes, but none of Taf4b-regulated germ stem cell genes in testes. Genome-wide ChIP-seq studies indicate that TAF7L binds to promoters of activated post-meiotic genes in testis. Moreover, biochemical studies show that TAF7L associates with TRF2 both in vitro and in testis suggesting that TAF7L likely cooperates directly with TRF2 at promoters of a subset of post-meiotic genes to regulate spermiogenesis. Our findings thus provide a new mechanism for cell-type specific transcriptional control involving an interaction between a ‘non-prototypic’ core promoter recognition factor (Trf2) and an orphan TAF subunit (Taf7l) in mammalian testis-specific gene transcription. Genome-wide mapping of TAF7L and Pol II in testis tissue, and mRNA-seq expression profiling wild type and Taf7l knockout testis.
Project description:Spermatogenesis is a complex process of sperm generation, including mitosis, meiosis, and spermiogenesis. During spermiogenesis, histones in post-meiotic spermatids are removed from chromatin and replaced by protamines. Although histone-to-protamine exchange is important for sperm nuclear condensation, the underlying regulatory mechanism is still poorly understood. Here, we identify PHD finger protein 7 (PHF7) as an E3 ubiquitin ligase for histone H3K14 in post-meiotic spermatids. Generation of Phf7-deficient mice and Phf7 C160A knockin mice with impaired E3 ubiquitin ligase activity reveals defects in histone-to-protamine exchange caused by dysregulation of histone removal factor Bromodomain, testis-specific (BRDT) in early condensing spermatids. Surprisingly, E3 ubiquitin ligase activity of PHF7 on histone ubiquitination leads to stabilization of BRDT by attenuating ubiquitination of BRDT. Collectively, our findings identify PHF7 as a critical factor for sperm chromatin condensation and contribute to mechanistic understanding of fundamental phenomenon of histone-to-protamine exchange and potential for drug development for the male reproduction system.
Project description:Taf7l (a paralogue of Taf7) and Trf2 (a TBP-related protein) are components of the core promoter complex required for gene/tissue-specific transcription of protein-coding genes by RNA polymerase II. Previous studies reported that Taf7l knockout mice exhibit structurally abnormal sperm, reduced sperm count, weakened motility and compromised fertility. Here we find that continued backcrossing of Taf7l-/Y mice from N5 to N9 produced KO males that are essentially sterile. Genome-wide expression profiling by mRNA-seq analysis of wild type (WT) and Taf7l-/Y (KO) testes revealed that Taf7l ablation impairs the expression of many post-meiotic spermatogenic specific as well as metabolic genes. Importantly, histological analysis of testes revealed that Taf7l-/Y mice develop post-meiotic arrest at the first stage of spermiogenesis, phenotypically similar to Trf2-/- mice, but distinct from Taf4b-/- mice. Indeed, we find that Taf7l and Trf2 co-regulate post-meiotic genes, but none of Taf4b-regulated germ stem cell genes in testes. Genome-wide ChIP-seq studies indicate that TAF7L binds to promoters of activated post-meiotic genes in testis. Moreover, biochemical studies show that TAF7L associates with TRF2 both in vitro and in testis suggesting that TAF7L likely cooperates directly with TRF2 at promoters of a subset of post-meiotic genes to regulate spermiogenesis. Our findings thus provide a new mechanism for cell-type specific transcriptional control involving an interaction between a ‘non-prototypic’ core promoter recognition factor (Trf2) and an orphan TAF subunit (Taf7l) in mammalian testis-specific gene transcription.
Project description:In mammals, the X and Y chromosomes are subject to meiotic sex chromosome inactivation (MSCI) during prophase I in the male germline, but their status thereafter is currently unclear. An abundance of X-linked spermatogenesis genes has spawned the view that the X must be active [1-8]. On the other hand, the idea that the imprinted paternal X of the early embryo may be pre-inactivated by MSCI suggests that silencing may persist longer [9-12]. To clarify this issue, we establish a comprehensive X-expression profile during mouse spermatogenesis. Here, we discover that the X and Y occupy a novel compartment in the post-meiotic spermatid and adopt a non-Rabl configuration. We demonstrate that this post-meiotic sex chromatin (PMSC) persists throughout spermiogenesis into mature sperm and exhibits epigenetic similarity to the XY body. In the spermatid, 87% of X-linked genes remain suppressed post-meiotically, while autosomes are largely active. We conclude that chromosome-wide X-silencing continues from meiosis to the end of spermiogenesis and discuss implications for proposed mechanisms of imprinted X-inactivation. Independent germ cell preps were used for array analysis. Duplicates were provided for each sample.
Project description:Male germ cells establish a unique heterochromatin domain, the XY-body, early in meiosis. How this domain is maintained through the end of meiosis and into post-meiotic germ cell differentiation is poorly understood. ADAD2 is a late meiotic male germ cell specific RNA binding protein, loss of which leads to post-meiotic germ cell defects. Analysis of ribosome association in Adad2 mutants revealed defective translation of Mdc1, a key regulator of XY-body formation, late in meiosis. As a result, Adad2 mutants show normal establishment but failed maintenance of the XY-body. Observed XY-body defects are concurrent with abnormal autosomal heterochromatin and ultimately lead to severely perturbed post-meiotic germ cell heterochromatin and cell death. These findings highlight the requirement of ADAD2 for Mdc1 translation, the role of MDC1 in maintaining meiotic male germ cell heterochromatin, and the importance of late meiotic heterochromatin for normal post-meiotic germ cell differentiation.
Project description:We conducted a genome-wide expression analysis of wild-type males using three cell populations isolated from mitotic, meiotic and post-meiotic phases of spermatogenesis in Drosophila melanogaster. Our approach was to directly isolate testis regions enriched with RNAs from each of the three specific germline phases. We used microarrays to detail the global gene expression profile in spermatogenesis and identified up- and down-regulated genes between two different spermatogenic phases in pairwise comparisons Experiment Overall Design: Cell types present at various stages of spermatogenesis are generally located in a gradient along the proximal-distal axis of the testis, however most are not exclusively restricted to any one geographic region. Cells enriched for mitotic, meiotic and post-meiotic phases were obtained by dissection of apical, proximal and distal regions of the testis, respectively
Project description:We conducted a genome-wide expression analysis of wild-type males using three cell populations isolated from mitotic, meiotic and post-meiotic phases of spermatogenesis in Drosophila melanogaster. Our approach was to directly isolate testis regions enriched with RNAs from each of the three specific germline phases. We used microarrays to detail the global gene expression profile in spermatogenesis and identified up- and down-regulated genes between two different spermatogenic phases in pairwise comparisons
Project description:Tadpole-shaped sperm is formed from round spermatid by spermiogenesis, a process with dramatic morphological changes in the final stage of spermatogenesis in testis. Protein phosphorylation, as one of the most important post-translational modifications, can regulate spermiogenesis, however, there is a lack of systemic analysis for phosphorylation events in this process. By large-scale phosphoproteome profiling using IMAC and TiO2 enrichment, we identified 18,980 phosphorylation sites in 4,628 phosphoproteins in mouse purified spermatids undergoing spermiogenesis. The identified phosphoproteins were significantly enriched in RNA transport, cell-cell adhesion, centrosome, microtubule and cilliogenesis. Further characterization of the kinase substrate relationship network demonstrated enrichment of phosphorylation substrates were related to the regulation of spermiogenesis. This global protein phosphorylation landscape of spermiogenesis showed wide phosphoregulation of diverse processes during spermiogenesis and could help further characterization of the process of sperm generation.
Project description:EWSR1-FLI1 is a chimeric transcription factor resulting from the pathognomonic translocation present in Ewing sarcoma cells. Here, we silenced EWSR1-FLI1 in different Ewing sarcoma cell lines. RNA from SKNMC, TC71 and MHH-ES1 cells was extracted 96h post transfection (siCT or siEWSR1-FLI1) or prior doxycycline (day 0) and 7 days after inducing silencing of EWSR1-FLI1 with doxycycline in ASP14 cells. RNA-seq was performed for all conditions.