Project description:Obesogens such as tributyltin (TBT) are xenobiotic compounds that promote obesity, in part by distorting the normal balance of lipid metabolism. The obesogenic effects of TBT can be observed in directly exposed (F1 and F2 generations) and also subsequent generations (F3 and beyond) that were never exposed. To address the effects of TBT exposure on germ cells, we exposed pregnant transgenic OG2 mouse dams (F0), which specifically express EGFP in germline cells, to an environmentally relevant dose of TBT throughout gestation through drinking water. When fed with a high fat diet (HFD), F3 male offspring of TBT-exposed F0 dams (TBT-F3) accumulated much more body fat than did Control-F3 males. TBT-F3 males also lost more body fluid and lean compositions than did Control-F3 males. Expression of genes involved in transcriptional regulation or mesenchymal differ-entiation was upregulated in somatic cells of TBT-F1 (but not TBT-F3) E18.5 fetal testes, and promoter-associated CpG islands were hyper-methylated in TBT-F1 somatic cells. Global mRNA expression of protein-coding genes in F1 or F3 fetal testicular cells was unaffected by F0 exposure to TBT; however, expression of a subset of endogenous retroviruses was significantly affected in F1 and F3. We infer that TBT may directly target testicular somatic cells in F1 testes to irreversibly affect epigenetic suppression of endogenous retroviruses in both germline and somatic cells.
Project description:Pro-spermatogonia (SG) serve as the gateway to spermatogenesis. Using single-cell RNA sequencing (RNAseq), we studied the development of ProSG, their SG descendants, and testicular somatic cells, during the perinatal period in mice. We identified both gene and protein markers for 3 temporally distinct ProSG cell subsets, including a migratory cell population with a distinct transcriptome from the previously defined T1- and T2-ProSG stages. This intermediate (I)-ProSG subset translocates from the center of seminiferous tubules to the spermatogonial stem cell (SSC) “niche” in its periphery soon after birth. We identified 3 undifferentiated SG subsets at postnatal day 7, each of which express distinct genes, including transcription factor and signaling genes. Two of these subsets have the characteristics of newly emergent SSCs. We also molecularly defined the development of Sertoli, Leydig, and peritubular myoid cells during the perinatal period, allowing us to identify candidate signaling pathways acting between somatic and germ cells in a stage-specific manner during the perinatal period. Our study provides a rich resource for those investigating testicular germ and somatic cell developmental during the perinatal period.
Project description:Sry is sufficient to induce testis formation and subsequent male development of internal and external genitalia in chromosomally female mice and humans. In XX sex-reversed males such as XX/Sry-transgenic (XX/Sry) mice, however, testicular germ cells always disappear soon after birth due to germ cell autonomous defects. Therefore, it remains unclear whether or not Sry alone is sufficient to induce a fully functional testicular soma capable of supporting complete spermatogenesis in the XX body. Here we demonstrated that the testicular somatic environment of XX/Sry males is defective in the later phases of spermatogenesis. Spermatogonial transplantation analyses using XX/Sry male mice revealed that donor XY spermatogonia are capable of proliferating, entering meiosis and differentiating into the round spermatid stage. XY donor-derived round spermatids, however, were frequently detached from the XX/Sry seminiferous epithelia and underwent cell death, thereby preventing further progress beyond the elongated spermatid stage. In contrast, immature XY seminiferous tubule segments transplanted under XX/Sry testis capsules clearly displayed proper differentiation into elongated spermatids in the transplanted XY donor tubules. Microarray analysis of seminiferous tubules isolated from XX/Sry testes confirmed missing expression of several Y-linked genes and alterations in the expression profile of genes associated with spermatogenesis. Therefore, our findings indicate dysfunction of the somatic tubule components, probably Sertoli cells, of XX/Sry testes, supporting our hypothesis that Sry alone is insufficient to induce a fully functional Sertoli cell in XX mice. Keywords: comparative genomic hybridization
Project description:Taking advantage of the tesco-cfp transgenic mouse line in which CFP is exclusively expressed in Sertoli cells under the control of a testis-specific enhancer (tesco), we established an embryonic stem cell from the mouse line (i.e. tcESC). We also created tcESC constitutively expressing mouse Sf1 transgene (tc;Sf1ESC). When we induced the differentiation of the two ESC lines into testicular somatic cell-like cells (TesLCs), tc;Sf1ESCs efficiently developed seminiferous tubule-like structures with the appearance of CFP-positive Setoli cell-like cells (SCLCs) in the tubules. On the other hand, epiblast-like cells (EpiLCs) were generated from ESCs having a germ cell-specific Prdm1-gfp transgene. Co-culture of tc;Sf1TesLCs with Prdm1-gfp EpiLCs resulted in self-organised aggregates, or testicular organoids. In the organoid, the EpiLCs differentiated into GFP-positive PGCLCs or gonocyte-like cells that were enclosed within a seminiferous tubule-like structure composed of CFP-positive SCLCs.