Osa在果蝇卵巢生殖干细胞分化中的功能研究

Function of Osa in the Differentiation of Drosophila Ovary Germline Stem Cell

果蝇卵巢生殖干细胞(Germline stem cell,GSC)是在活体(in vivo)研究干细胞命运调控的理想平台。表观遗传机制在果蝇卵巢GSC命运调控中发挥重要作用,其机理的探明需要研究并发现更多参与此过程的表观调控因子。为探究果蝇染色质重塑复合物BAP中特有的亚基Osa在果蝇卵巢GSC分化调控中的功能及其分子机理,利用GAL4/UAS二元表达系统结合RNAi技术在干细胞微环境组分护卫细胞(Escort cells,ECs)中特异性下调osa的表达,并通过免疫荧光染色法对相关指标进行检测。结果显示,敲减ECs中osa可致卵巢组织卵原区中未分化生殖细胞数目(Undifferentiated germ cells,UGCs)显著增多,同时BMP信号通路激活标志p Mad、Dad-lacZ阳性细胞数目显著增多,并观察到EC细胞形态异常,不能有效包裹生殖系细胞。推论Osa以BMP信号通路依赖方式参与果蝇卵巢GSC的分化调控,其作用机理还可能涉及EC细胞特定的形态学过程。

The Drosophila ovary germline stem cell（GSC）is recognized as an ideal model system for studying stem cell fate regulationin vivo. The epigenetic mechanism is involved in the Drosophila ovary GSC fate regulation. Identification and characterization of apparentepigenetic regulators involved in this process will contribute to reveal underlying regulatory mechanisms. The aim of this study is to investigatethe possible functions and the molecular mechanisms of Osa,the chromatin remodeling complex BAP-specific subunit,in Drosophila GSCdifferentiation. GAL4/UAS binary system combined with RNAi technology was used to specifically down-regulate osa expression in escort cells（ECs）,and immune fluorescent dyeing was for detecting the relevant indexes. The results showed that knock-down of osa led to a significantincrease of undifferentiated germ cells（UGCs）in the germarium of ovarian tissue,the positive cells of p Mad and Dad-lac Z,two BMPsignaling activity reporters,increased significantly. Moreover,EC morphology was abnormal,and they failed to wrap germline cells. Inconclusion,Osa might be involved in the regulation of GSC differentiation by BMP signaling pathway-depending and specific morphologicalprocess of ECs.