Tulina N, Matunis E
Department of Embryology, Carnegie Institution of Washington, 115 West University Parkway, Baltimore, MD 21210, USA.
Science. 2001 Dec 21;294(5551):2546-9. doi: 10.1126/science.1066700.
Stem cells, which regenerate tissue by producing differentiating cells, also produce cells that renew the stem cell population. Signals from regulatory microenvironments (niches) are thought to cause stem cells to retain self-renewing potential. However, the molecular characterization of niches remains an important goal. In Drosophila testes, germ line and somatic stem cells attach to a cluster of support cells called the hub. The hub specifically expresses Unpaired, a ligand activating the JAK-STAT (Janus kinase-signal transducer and activator of transcription) signaling cascade. Without JAK-STAT signaling, germ line stem cells differentiate but do not self-renew. Conversely, ectopic JAK-STAT signaling greatly expands both stem cell populations. We conclude that the support cells of the hub signal to adjacent stem cells by activation of the JAK-STAT pathway, thereby defining a niche for stem cell self-renewal.
干细胞通过产生分化细胞来再生组织，同时也产生能够更新干细胞群体的细胞。来自调节性微环境（壁龛）的信号被认为可使干细胞保持自我更新潜能。然而，壁龛的分子特征仍是一个重要目标。在果蝇睾丸中，生殖系干细胞和体细胞干细胞附着于一群称为“枢纽”的支持细胞上。“枢纽”特异性表达“未配对”蛋白，这是一种激活JAK-STAT（Janus激酶-信号转导及转录激活蛋白）信号级联反应的配体。没有JAK-STAT信号时，生殖系干细胞会分化但不会自我更新。相反，异位的JAK-STAT信号会极大地扩增这两种干细胞群体。我们得出结论，“枢纽”中的支持细胞通过激活JAK-STAT通路向相邻干细胞发出信号，从而为干细胞自我更新定义了一个壁龛。
