Role of ngn3, a bHLH transcription factor, in the establishment and maintenance of the mouse spermatogenic stem cells

点击翻译按钮获取中文摘要

The aim of this study was to investigate the establishment of the spermatogenic stem cells, their behaviors in the mature testes, and the underlying molecular mechanisms. This has been done taking advantages of our previous identification of ngn3 (neurogenin3, a basic-helix-loop-helix transcription factor), which is expressed in undifferentiated spermatogonia, a tiny spermatogonial population that harbors the stem cell function.Emergence of the ngn3+ undifferentiated spermatogonia was investigated during the pre-pubertal and pubertal periods and it has been revealed that the very first round of spermatogenesis lacks the ngn3+ undifferentiated spermatogonia stage, while the following waves and spermatogenesis found in matured testes were all derived from the ngn3-positive undifferentiated spermatogonia. This indicates that the stem cell stage may not be indispensable for the spermatogenic differentiation process and provides an intriguing notion widely for the stem cell study. In addition, it is suggested that some of the Ngn3+ spermatogonia play very important roles for the occasional loss of actually self-renewing stem cells and replenish the stem cell pool, which is important for the long-term robustness of the spermatogenesis.These results would provide basic findings valuable for the strategy against upcoming human problems such as male infertility or overpopulation.