Drosophila heparan sulfate 3-0 sulfotransferase B Null Mutant Is Viable and Exhibits No Defects in Notch Signaling

Heparan sulfate proteoglycans （HSPGs） are critically involved in a variety of biological events. The functions of HSPGs are determined by the nature of the core proteins and modifications of heparan sulfate （HS） glycosaminoglycan （GAG） chains. The distinct O-sulfo- transferases are important for nonrandom modifications at specific positions. Two HS 3-0 sulfotransferase （Hs3st） genes, Hs3st-A and Hs3st-B, were identified in Drosophila. Previous experiments using RNA interference （RNAi） suggested that Hs3st-B was required for Notch signaling. Here, we generated a null mutant of Hs3st-B via ends-out gene targeting and examined its role（s） in development. We found that homozygous Hs3st-B mutants have no neurogenic defects or alterations in the expression of Notch signaling target gene. Thus, our results strongly argue against an essential role for Hs3st-B in Notch signaling. Moreover, we have generated two independent Hs3st-A RNAi lines which worked to deplete Hs3st-A. Importantly, Hs3st-A RNAi combined with Hs3st-B mutant flies did not alter the expression of Notch signaling components, arguing that both Hs3st-A and Hs3st-B were not essential for Notch signaling. The establishment of Hs3st-B mutant and effective Hs3st-A RNAi lines provides essential tools for further studies of the physiological roles of Hs3st-A and Hs3st-B in development and homeostasis.     

甲状腺肿瘤细胞中p16基因的表达和突变

目的:研究抑癌基因p16在甲状腺肿瘤中的表达及突变.方法:采用免疫组织化学法检测60例甲状腺肿瘤细胞中p16蛋白的表达;采用聚合酶链式反应检测甲状腺肿瘤细胞中p16基因的缺失及外显子15'CpG岛异常甲基化.结果:60例甲状腺肿瘤中p16蛋白阳性表达为46.7%(28/60);30例腺瘤中p16蛋白阳性表达分别为60.0%(18/30);30例腺癌中则为33.3%(10/30).60例甲状腺肿瘤中p16基因缺失为13.3%(8/60),30例腺癌中p16基因缺失为26.7%(8/30);30例腺瘤中无缺失(0/30),组间比较差异有显著性(P＜0.05).60例甲状腺肿瘤中p16基因外显子15'CpG岛异常甲基化为15.0%(9/60);30例腺癌中为30.0%(9/30);30例腺瘤中无外显子15'CpG岛异常甲基化(0/30),组间比较差异有显著性(P＜0.001).结论:抑癌基因p16参与了甲状腺肿瘤的发生发展,p16基因的缺失和外显子15'CpG岛异常甲基化在甲状腺恶性肿瘤中起一定的作用,并可能是甲状腺肿瘤中p16基因失活的主要机制.