Spermatogonial stem cells (SSCs) are at the foundation of mammalian spermatogenesis, maintainingsperm production throughout adult life. The molecular mechanisms that control the critical self-renewal vs.differentiation fate decision of SSCs are largely unknown. The hypothesis is that transcription factors primarilyrestricted to stem and progenitor spermatogonia form regulatory networks to execute gene expressionprograms important for SSC fate decisions and spermatogenesis.
Three Specific Aims will test this hypothesis. Experiments in Specific Aim 1 will employ functional genetics to determine if specific transcription factorsare essential for spermatogenesis using a knockdown strategy in ex vivo SSC cultures followed bytransplantation to assess stem cell and spermatogenic activity.
Specific Aim 2 will identify the target generepertoire of SSC transcription factors by ChIP-Seq and reveal conserved and unique targets sets.Experiments in Specific Aim 3 will confirm mechanisms of target gene regulation by EMSA and transienttransfection transcriptional analysis. These results will form the basis of gene regulatory network modelsincorporating complex interactions from multiple factors contributing to gene regulation and SSC potential. The proposed studies will be enhance the independent career trajectory of the PI (Brian Hermann) byestablishing a new research focus investigating the fundamental regulation of SSCs in the rodent testis underthe mentorship of Dr. Kyle Orwig. This is a new research direction for the PI who has established expertise inSertoli cell gene regulation and primate spermatogenesis and stem cells. The intellectual and technicalenvironment for research in reproductive biology and stem cells at the Magee-Womens Research Institute andUniversity of Pittsburgh is outstanding, all resources required to complete the studies are available, and thereis a strong reputation for promoting development of new investigators. This combination of a PI withoutstanding potential for independence, an innovative mentor, and superior environment will facilitate allaspects of the proposed studies and advancement of PI's career towards independence. The long-term career goals of the PI are to establish an independent research program in a tenure-trackfaculty position, make significant scholarly contributions to the understanding of SSCs and spermatogenesis,and develop new approaches for treating male infertility. Three immediate objectives to promote the transitionto independence are addressed by the career development award: 1) develop an independent research niche,2) demonstrate outstanding productivity, and 3) secure additional independent funding. The careerdevelopment plan involves conceptual mentoring in functional genetics, technical training relating to cultureand transplantation of SSCs in the mouse model, instruction in bioinformatics data analysis, informal andstructured mentoring in areas relevant to running a successful independent research program, and evaluationof career development progress by an external advisory board. Ultimately, these studies may provide insights about the mechanisms that initiate and maintainspermatogenesis, which has implications for treating male infertility. Investigating the biological properties ofSSCs may also expand the understanding of how stem cells behave and contribute to the normal function of avariety of adult tissues. Moreover, additional nurturing of the candidate's career development will promote acompetitive, independent research career to contribute substantively to the biomedical sciences.
Spermatogonial stem cells (SSCs) are responsible for sperm production throughout adult life and are essential for male fertility. The methods which instruct these cells to behave like stem cells and maintain sperm production are unknown. The unique combination of genes expressed by SSCs and the proteins that turn these genes on and off may control of SSC behavior. This application will provide key insights about the role of gene regulation in normal SSC behavior, which may reveal underlying causes of male infertility.
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