Notch信号途径中的Su(H)和E(spl)基因对果蝇天然免疫的影响

天然免疫系统是多细胞生物抵抗各种入侵微生物的第一道防线.Notch途径介导相邻细胞之间的相互作用,调节细胞、组织、器官的分化和发育.为了进一步探索Notch信号途径在果蝇天然免疫中的功能,利用Notch途径下游基因Su(H)和E(spl)的低表达突变体果蝇,通过体外注射病原体分析了生存率、血细胞的噬菌功能和抗菌肽的表达量以及突变体的血细胞数量.结果表明,革兰氏阴性细菌和真菌感染后果蝇E(spl)突变体的生存率、噬菌能力及抗菌肽的表达量明显降低,而且幼虫期血细胞出现异常增殖;Su(H)突变体只对真菌表现出敏感性,抗菌肽的表达量降低,但是对真菌的噬菌能力正常.此结果表明,Notch途径不仅影响个体的生长发育,而且在果蝇天然免疫中也起重要的调节作用.

The E(spl) and Su(H) of Notch Signaling Are Required for Regulating of Drosophila Innate Immunity

The innate immune system is the first line of the multicellular organism against the various pathogens invading. The Notch signaling plays a significant role in maintaining the balance among cell proliferation, differentiation, apoptosis and development. To further investigate the function of Notch signaling pathway in Drosophila innate immunity, Drosophila mutants, E(spl) and Su(H), which are located in the downstream of Notch signaling pathway, were utilized to analyze the survival rate, in vivo phagocytosis and production of antimicrobial peptides after pathogen infections. In addition, the number of circulating plasmatocytes in third instar larvae of mutant and wild type flies was also measured. The results indicate that the E(spl) mutant showed lower survival rate, phagocytosis and the expression of AMP genes after pathogen infections. Furthermore, an abnormal increase in the number of plasmatocytes in E(spl) mutant larvae was also observed. Compared with E(spl) mutant, the mutant of Su(H) only showed sensitive to fungi, however, phagocytic ability of hemocytes was normal in fungi infection. At the same time, the expression of antimicrobial peptides was decreased in Su(H) mutant. These results show that the Notch pathway not only affects the growth and development of individuals, but also plays an important role in regulating innate immunity of Drosophila.