Waskar Morris, Li Yishi, Tower John
Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, 835 W. 37th St., University Park, Los Angeles, CA 90089-1340 USA.
Age (Dordr). 2005 Sep;27(3):201-12. doi: 10.1007/s11357-005-2914-1. Epub 2005 Dec 31.
Accumulating evidence suggests that with time human stem cells may become defective or depleted, thereby contributing to aging and aging-related diseases. Drosophila provides a convenient model system in which to study stem cell aging. The adult Drosophila ovary contains two types of stem cells: the germ-line stem cells give rise to the oocyte and its supporting nurse cells, while the somatic stem cells give rise to the follicular epithelium-a highly differentiated tissue that surrounds each oocyte as it develops. Genetic and transgenic analyses have identified several conserved signaling pathways that function in the ovary to regulate stem cell maintenance, division and differentiation, including the wingless, hedgehog, JAK/STAT, insulin and TGF-β pathways. During Drosophila aging the division of the stem cells decreases dramatically, coincident with reduced egg production. It is unknown if this reproductive senescence is due to a defect in the stem cells themselves, or due to the lack of signals normally sent to the stem cells from elsewhere in the animal, such as from the central nervous system or the stem cell niche. Methods are being developed to genetically mark stem cells in adult Drosophila and measure their survival, division rate and function during aging.
越来越多的证据表明，随着时间的推移，人类干细胞可能会变得有缺陷或耗尽，从而导致衰老和与衰老相关的疾病。果蝇提供了一个便于研究干细胞衰老的模型系统。成年果蝇卵巢含有两种类型的干细胞：生殖系干细胞产生卵母细胞及其支持性的滋养细胞，而体干细胞产生卵泡上皮——一种高度分化的组织，在每个卵母细胞发育时围绕着它。遗传和转基因分析已经确定了几种在卵巢中起作用以调节干细胞维持、分裂和分化的保守信号通路，包括无翅、刺猬、JAK/STAT、胰岛素和TGF-β通路。在果蝇衰老过程中，干细胞的分裂显著减少，同时产卵量也减少。目前尚不清楚这种生殖衰老是否是由于干细胞本身的缺陷，还是由于动物其他部位（如中枢神经系统或干细胞微环境）通常向干细胞发送的信号缺失所致。目前正在开发一些方法，用于在成年果蝇中对干细胞进行基因标记，并测量它们在衰老过程中的存活率、分裂率和功能。
