The molecular mechanisms regulating niche signal distribution in Drosophila germline stem cell niche.

干细胞具有显着的特征，可以产生保持干细胞身份的子细胞，而另一个子细胞则分化。干细胞存在于专门的细胞微环境中，这种微环境被称为干细胞微环境。这些小生境决定了干细胞的身份，维持干细胞种群，并协调分化细胞的适当内环境平衡生产。果蝇生殖系干细胞(GSCs)是体内干细胞研究的理想模型之一。在雄性和雌性性腺顶端，GSCs与特殊分化的体细胞性腺细胞--壁龛细胞相联系。这些利基细胞通过分泌信号分子为GSCs产生利基。虽然这些事实表明这些配体的空间分布决定了生态位区域，但调节生态位内配体分布的分子机制尚不清楚。在本研究中，我们证明了果蝇硫酸乙酰肝素蛋白多糖(HSPGs)是GSC生态位的重要组成部分。果蝇HSPG亚家族中的两个Glypia在雌性和雄性性腺的壁龛细胞中表达，是维持GSC所必需的。相反，当Glypcan在卵巢异位表达时，我们观察到GSC生态位的扩张。这些结果表明，这些水蚤从分子上定义了生态位区域。

Stem cell posses the remarkable characteristics to produce its daughter cell that retain a stem-cell identity and the other that differentiates. Stem cells reside in dedicated cellular microenvironments termed stem-cell niches. These niches dictate a stem-cell identity, maintain the stem cell population, and coordinate proper homeostatic production of differentiated cells. Drosophila germ line stem cells(GSCs) are one of the ideal models for stem cell study in vivo. In apical tips of both male and female gonads, GSCs associate with specially differentiated somatic gonadal cells, the niche cells. These niche cells generate niches for GSCs by secreting signaling molecules. Although these facts indicate that region of niche is defined by the spatial distribution of these ligands, molecular mechanisms that regulate ligand distribution within the niche is not characterized.In this study, we showed that Drosophila Heparan Sulfate Proteoglycans(HSPGs) are essential components of GSC niche. Drosophila two glypians, a subfamily of HSPGs, were expressed in niche cells of female and male gonads and were required for GSC maintenance. Conversely, when glypican was ectopically expressed in ovaries, we observed expansion of GSC niche. These results showed that these glypicans define niche region molecularly.