Transcriptome Analysis Of Mouse Germline Stem Cells And Functional Research Of Pramef12

Germline stem cells are unique adult stem cells that are responsible for transmitting genetic information from parents to subsequent generations. Germline stem cells include spermatogonial stem cells(SSC) also called male germline stem cells and female germline stem cells(FGSC). There is no report on whether these two kinds of germline stem cells share similar characteristics. In this paper, we focused on the above two kinds of germline stem cells. Firstly, we explored the similar characters of FGSC and SSC at transcriptome level. Secondly, we systematically explored the mechanism of SSC self-renewal, which provided some useful clues for FGSC self-renewing.In the first part of this study, we first compared the transcriptomes between freshly isolated FGSC and grape-like FGSC formed after two days’ culturing(FGSCalign). We found 65 different coverages on the chromosomes of FGSC and FGSCalign and 84 differentially expressed genes. We found 108 and 139 new alternative splicing sites in FGSC and FGSCalign, respectively. The comparison of transcriptomes between freshly isolated FGSC and FGSCalign laid the foundation for further study on proliferation of FGSC. Second, we found that FGSC and SSC not only had similar morphological characters but also sharing similar signatures at the transcriptome level. Eight hundred fifty-three co-highly expressed genes(CEG) in FGSC and SSC were found by microarray analysis. The similar morphological and molecular signatures between FGSC and SSC might be decided by these 853 genes. We constructed a continuous network to prediect interactions between those CEG by breadth first search. The constructed network provided some clues for futher research on germline stem cell. Eighteen genes were identified as core genes shared by germline stem cells, mouse embryonic stem cells, neural stem cells, and hematopoietic stem cells. By functional analysis of those CEG, we found 17 transcription factors involved in cell proliferation, cell division and cell cycle. From the network, we sought out the interactions of the CEG responsible for maintaining the properties of germline stem cells.In the second part of this study, twenty three genes essential for SSC self-renewal were severed as seed proteins to construct a protein-protein interaction(PPI) network relate to SSC self-renewal. This PPI network consists of 246 nodes connected by 844 edges. Topological analyses of the PPI network identified several genes and modules essential for maintaining SSC self-renewal. As one core gene for maintaining SSC self-renewal, pouf51 was verified again by system biology perspective. The study on FGSC is a new research area, thus, there is seldom finding about the mechanism of FGSC self-renewal. The SSC self-renewal PPI network would serve as a reference for FGSC studies. At the same time, we also studied the function of Pramef12, which highly expressed in freshly isolated SSC identified by previous high-throughput experiment. The expression of Pramef12 was dynamically changed during the development of testis. Overexpression of Pramef12 enhances the sensitivity of SSC to apoptosis-inducing agent. Along with the space-time characters of Pramef12 expression, we hypothesized that Pramef12 may plays several roles in the first wave of spermatogonia apoptosis during spermatogenesis.Taken together, we found that FGSC and SSC sharing the similar stem cell features. Meanwhile, the constructed SSC self-renewal PPI network provided references to futher study of FGSC self-renewal. This study is helpful for exploring the molecular mechanisms of self-renewal in germline stem cell. This study also provides theoretic foundation for clinical diagnosis, treatment and prevention of infertility.