Project description:Epigenetic mechanisms including DNA methylation, non-coding RNAs and histone modifications control gene expression. Studies suggest that a father's lifetime experiences can be transmitted to his offspring to affect development and health. The mechanisms underlying such epigenetic inheritance are unknown. A potential route for paternal transmission is the unique chromatin composition of spermatozoa. Unlike somatic cells and oocytes, most nucleosomes in sperm are replaced with protamine nucleoproteins. The role of residual nucleosomes, residing at gene regulatory sequences, for epigenetic control of embryonic development is unknown. Here we generated a transgenic mouse model in which over-expression of the histone H3 lysine 4 (H3K4) demethylase LSD1/KDM1A during spermatogenesis alters H3K4 methylation in sperm. Strikingly, KDM1A over-expression in one generation causes severe embryonic defects in non-transgenic descendants spanning three subsequent generations. We show for the first time that correct histone methylation homeostasis during spermatogenesis is critical for offspring development and survival over multiple generations. Identification of H3K4me2 and nucleosome occupancies in sperm of wildtype mice, KDM1A transgenic mice and their non-transgenic littermates.
Project description:Male mammals must simultaneously produce prodigious numbers of sperm and maintain an adequate reserve of stem cells to ensure continuous production of gametes throughout life. Failures in the mechanisms responsible for balancing germ cell differentiation and spermatogonial stem cell (SSC) self-renewal can result in infertility. We discovered a novel requirement for Ubiquitous Expressed Transcript (UXT) in spermatogenesis by developing the first knockout mouse model for this gene. Constitutive deletion of Uxt is embryonic lethal, while conditional knockout in the male germline results in a Sertoli cell-only phenotype during the first wave of spermatogenesis that does not recover in the adult. This phenotype begins to manifest between 6 and 7 days post-partum, just before meiotic entry. Gene expression analysis revealed that Uxt deletion downregulates the transcription of genes governing SSC self-renewal, differentiation, and meiosis, consistent with its previously defined role as a transcriptional co-factor. Our study has revealed the first in vivo function for UXT in the mammalian germline as a regulator of distinct transcriptional programs in SSCs and differentiating spermatogonia.
Project description:Spermatogenesis is a highly complex developmental process that typically consists of mitosis, meiosis, and spermiogenesis. DNA/RNA helicase DHX36, a unique guanine-quadruplex (G4) resolvase, play crucial roles in a variety of biological processes. We previously showed that DHX36 is highly expressed in male germ cells with the highest level in zygotene spermatocytes. Here, we delete Dhx36 in advanced germ cells with Stra8-GFPCre, and found that a Dhx36 deficiency in the differentiated spermatogonia leads to meiotic defects and abnormal spermiogenesis. These defects in late stages of spermatogenesis arise from dysregulated transcription of G4-harboring genes, which are required for meiosis. Thus, this study reveals that Dhx36 play crucial roles in the late stages of spermatogenesis.
Project description:Intracellular calcium signaling is critical for initiating and sustaining diverse cellular functions including transcription, synaptic signaling, muscle contraction, apoptosis and fertilization. Trans-membrane 203 (TMEM203) was identified here in cDNA overexpression screens for proteins capable of modulating intracellular calcium levels using activation of a calcium/calcineurin regulated transcription factor as an indicator. Overexpression of TMEM203 resulted in a reduction of Endoplasmic Reticulum (ER) calcium stores and elevation in basal cytoplasmic calcium levels. TMEM203 protein was localized to the ER and found associated with a number of ER proteins which regulate ER calcium entry and efflux. Mouse Embryonic Fibroblasts (MEFs) derived from Tmem203 deficient mice had reduced ER calcium stores and altered calcium homeostasis. Tmem203 deficient mice were viable though male knockout mice were infertile and exhibited a severe block in spermiogenesis and spermiation. Expression profiling studies showed significant alternations in expression of calcium channels and pumps in testes and concurrently Tmem203 deficient spermatocytes demonstrated significantly altered calcium handling. Thus Tmem203 is an evolutionarily conserved regulator of cellular calcium homeostasis, is required for spermatogenesis and provides a causal link between intracellular calcium regulation and spermiogenesis. Testes were harvested from control and Tmem203 null mice at 24 weeks of age. 4 wild type testes and 5 null mice testes were probed using Affymetrix Mouse Genome 430 2.0 platform.
Project description:Serine/arginine-rich splicing factor 2 (SRSF2), also known as SC35, is a member of a SRs protein family, which plays significant roles in numerous fundamental biological activities. However, the roles and underlying mechanisms of SRSF2 remain largely unclear during spermatogenesis. Here, we report that SRSF2 is involved in alternative splicing and that male germ cell-specific deletion of Srsf2 by Stra8-GFPCre causes absolute infertility and defective spermatogenesis. Further analyses revealed that deletion of Srsf2 in the male germ cells had harmful influences on the differentiation of spermatogonia and meiosis initiation. Mechanistically, by combining RNA-seq data with LACE-seq data, we showed that spermatogenesis, meiotic cell cycle, male gamete generation, reproductive development, and male sex differentiation were involved in the SRSF2 regulatory networks. Furthermore, SRSF2 affects expression and AS of Stra8, Stag3 and Atr in a direct manner, which were critical factors during spermatogenesis. Taken together, our results demonstrate that SRSF2 has important functions in spermatogenesis and male fertility by regulating alternative splicing.
Project description:Serine/arginine-rich splicing factor 2 (SRSF2), also known as SC35, is a member of a SRs protein family, which plays significant roles in numerous fundamental biological activities. However, the roles and underlying mechanisms of SRSF2 remain largely unclear during spermatogenesis. Here, we report that SRSF2 is involved in alternative splicing and that male germ cell-specific deletion of Srsf2 by Stra8-GFPCre causes absolute infertility and defective spermatogenesis. Further analyses revealed that deletion of Srsf2 in the male germ cells had harmful influences on the differentiation of spermatogonia and meiosis initiation. Mechanistically, by combining RNA-seq data with LACE-seq data, we showed that spermatogenesis, meiotic cell cycle, male gamete generation, reproductive development, and male sex differentiation were involved in the SRSF2 regulatory networks. Furthermore, SRSF2 affects expression and AS of Stra8, Stag3 and Atr in a direct manner, which were critical factors during spermatogenesis. Taken together, our results demonstrate that SRSF2 has important functions in spermatogenesis and male fertility by regulating alternative splicing.
Project description:The centrosome is a conserved eukaryotic organelle essential for reproductive process, and centrosomal proteins (CEP) are necessary for composition of the centrosome. However, few CEPs have been genetically linked to fertility, and the related molecular mechanisms remains mysterious. Here, we identified a new CEP, CEP128, which is functional in spermatogenesis, fertilization and embryonic development in both humans and mice. The variants of CEP128/Cep128 could lead to aberrant centrosome structures of the sperm inducing to anomalies in sperm morphology, count as well as motility, and further result in male infertility, but did not grossly affect ciliogenesis. Mechanistically, both loss and up-regulation of CEP128 could cause suppressed expressions of the genes involved in the spermatogenesis and fertilization phase. Altogether, our findings unprecedentedly unveil a crucial role of CEP128 in male fertility and provides new insight into the function of CEPs in human disease.
Project description:Spermatogenesis is precisely controlled at the transcriptional, posttranscriptional, and translational levels. Here we report that N6-methyladenosine (m6A), an epitranscriptomic mark regulating gene expression, plays essential roles during spermatogenesis. We present comprehensive m6A mRNA methylomes of mouse spermatogenic cells from five developmental stages: undifferentiated spermatogonia, type A1 spermatogonia, preleptotene spermatocytes, pachytene/diplotene spermatocytes, and round spermatids. Germ cell-specific inactiva- tion of the m6A RNA methyltransferase Mettl3 or Mettl14 with Vasa-Cre causes loss of m6A and depletion of SSCs. m6A depletion dysregulates translation of transcripts that are required for SSC proliferation/differentiation. Com- bined deletion of Mettl3 and Mettl14 in advanced germ cells with Stra8-GFPCre disrupts spermiogenesis, whereas mice with single deletion of either Mettl3 or Mettl14 in advanced germ cells show normal spermatogenesis. The sper- matids from double-mutant mice exhibit impaired translation of haploid-specific genes that are essential for spermio- genesis. This study highlights crucial roles of mRNA m6A modification in germline development, potentially ensuring coordinated translation at different stages of spermatogenesis.
Project description:Male germ cell meiosis is essential for generating haploid spermatozoa in mice. Here, we investigate the essential role of DIS3 in male germ cell meiosis in mice. Conditional inactivation of DIS3 in spermatocytes with Stra8-cre transgenic mice have severely impaired meiotic progression, which results in defective meiosis and spermatogenesis. RNA-seq analysis reveals that Dis3 deficiency causes significant dysregulation of the expression of transcripts in mutant testes. Meiosis-associated genes are significantly decreased in the absence of DIS3. Therefore, we show that DIS3 ribonuclease plays a critical role in germ cell meiosis during spermatogenesis in mice.