| Budget Amount *help |
¥3,980,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥480,000)
Fiscal Year 2007: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2006: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Spermatogonial stem cells (SSCs) have unique properties to self-renew and support spermatogenesis throughout their lifespan. SSCs can proliferate in vitro in the presence of glial cell line-derived neurotrophic factor, a self-renewal factor for SSCs. These cultured SSCs are called germline stem (GS) cells. Although SSCs are normally committed to the germline, ES-like cell colonies develop spontaneously during GS cell culture from postnatal testis. These ES-like cells, called multipotent germline stem (mGS) cells, differentiate not only into somatic cells, but also into germ cells. In previous studies, it is known that germline cells such as ES cells and embryonic germ (EG) cells have the capacity to reprogram somatic nuclei after cell fusion. In this study, we investigated whether two type of germline cells derived from postnatal testis culture have the capacity similar to ES and EG cells. GS and mGS cells were established from newborn Green mice testes. These cells hybridized with thy
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mocytes, which derived from ROSA26 mice carrying a neo/lacZ transgene. It was possible to isolate hybrid clones by their resistance to G418 selection following cell fusion. GS-thymocyte hybrid cells were produced by electric or polyethylene glycol-mediated cell fusion ; however, these cells were not expanded by G418 selection because of low growth rate. mGS-thymocyte hybrid cells that maintained tetraploid chromosomes were clonally isolated by G418 selection and largely expanded. The morphology, growth rate, and characteristic gene expression patterns of these hybrid cells were similar to that of the mGS cells. These cells were able to differentiate into typical teratomas, which obtained tissues from three germ layers. Furthermore, the Oct-GFP transgene, which was repressed in thymocytes prior to cell fusion, was reactivated in the mGS-thymocyte hybrid cells. These results suggest that mGS cells through cell fusion can erase the developmental programming of somatic nulei and impose pluripotency. Less
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