Kanatsu-Shinohara Mito, Lee Jiyoung, Inoue Kimiko, Ogonuki Narumi, Miki Hiromi, Toyokuni Shinya, Ikawa Masahito, Nakamura Tomoyuki, Ogura Atsuo, Shinohara Takashi
Department of Molecular Genetics, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
Biol Reprod. 2008 Apr;78(4):681-7. doi: 10.1095/biolreprod.107.066068. Epub 2008 Jan 16.
Although pluripotent stem cells were recently discovered in postnatal testis, attempts to analyze their developmental potential have led to conflicting claims that spermatogonial stem cells are pluripotent or that they lose spermatogenic potential after conversion into pluripotent stem cells. To examine this issue, we analyzed the developmental fate of a single spermatogonial stem cell that appeared during transfection experiments. After transfection of a neomycin-resistance gene into germline stem cells, we obtained an embryonic stem-like, multipotent germline stem cell line. Southern blot analysis revealed that the germline stem and multipotent germline stem clones have the same transgene integration pattern, demonstrating their identical origin. The two lines, however, have different DNA methylation patterns. The multipotent germline stem cells formed chimeras after blastocyst injection but did not produce sperm after germ cell transplantation, whereas the germline stem cells could produce only spermatozoa and did not differentiate into somatic cells. Interestingly, the germline stem cells expressed several transcription factors (Pou5f1, Sox2, Myc, and Klf4) required for reprogramming fibroblasts into a pluripotent state, suggesting that they are potentially pluripotent. Thus, our study provides evidence that a single spermatogonial stem cell can acquire pluripotentiality but that conversion into a pluripotent cell type is accompanied by loss of spermatogenic potential.
尽管最近在出生后的睾丸中发现了多能干细胞，但对其发育潜能的分析尝试却引发了相互矛盾的说法，即精原干细胞是多能的，或者它们在转化为多能干细胞后会丧失生精潜能。为了研究这个问题，我们分析了在转染实验中出现的单个精原干细胞的发育命运。将新霉素抗性基因转染到生殖系干细胞后，我们获得了一种胚胎干细胞样的多能生殖系干细胞系。Southern印迹分析表明，生殖系干细胞克隆和多能生殖系干细胞克隆具有相同的转基因整合模式，证明它们起源相同。然而，这两个细胞系具有不同的DNA甲基化模式。多能生殖系干细胞在囊胚注射后形成嵌合体，但在生殖细胞移植后不产生精子，而生殖系干细胞只能产生精子，不会分化为体细胞。有趣的是，生殖系干细胞表达了将成纤维细胞重编程为多能状态所需的几种转录因子（Pou5f1、Sox2、Myc和Klf4），这表明它们可能具有多能性。因此，我们的研究提供了证据，表明单个精原干细胞可以获得多能性，但转化为多能细胞类型会伴随着生精潜能的丧失。
