Fukagawa Tatsuo, Nogami Masahiro, Yoshikawa Mitsuko, Ikeno Masashi, Okazaki Tuneko, Takami Yasunari, Nakayama Tatsuo, Oshimura Mitsuo
Precursory Research for Embryonic Science and Technology of Japan Science and Technology Agency, National Institute of Genetics and The Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan.
Nat Cell Biol. 2004 Aug;6(8):784-91. doi: 10.1038/ncb1155. Epub 2004 Jul 11.
RNA interference is an evolutionarily conserved gene-silencing pathway in which the nuclease Dicer cleaves double-stranded RNA into small interfering RNAs. The biological function of the RNAi-related pathway in vertebrate cells is not fully understood. Here, we report the generation of a conditional loss-of-function Dicer mutant in a chicken-human hybrid DT40 cell line that contains human chromosome 21. We show that loss of Dicer results in cell death with the accumulation of abnormal mitotic cells that show premature sister chromatid separation. Aberrant accumulation of transcripts from alpha-satellite sequences, which consist of human centromeric repeat DNAs, was detected in Dicer-deficient cells. Immunocytochemical analysis revealed abnormalities in the localization of two heterochromatin proteins, Rad21 cohesin protein and BubR1 checkpoint protein, but the localization of core kinetochore proteins such as centromere protein (CENP)-A and -C was normal. We conclude that Dicer-related RNA interference machinery is involved in the formation of the heterochromatin structure in higher vertebrate cells.
RNA干扰是一种进化上保守的基因沉默途径,其中核酸酶Dicer将双链RNA切割成小干扰RNA。RNAi相关途径在脊椎动物细胞中的生物学功能尚未完全了解。在此,我们报道了在含有人类21号染色体的鸡-人杂交DT40细胞系中产生了条件性功能丧失的Dicer突变体。我们表明,Dicer的缺失导致细胞死亡,并伴有显示姐妹染色单体过早分离的异常有丝分裂细胞的积累。在Dicer缺陷细胞中检测到由人类着丝粒重复DNA组成的α-卫星序列转录本的异常积累。免疫细胞化学分析揭示了两种异染色质蛋白Rad21黏连蛋白和BubR1检查点蛋白定位的异常,但着丝粒核心蛋白如着丝粒蛋白(CENP)-A和-C的定位正常。我们得出结论,Dicer相关的RNA干扰机制参与了高等脊椎动物细胞中异染色质结构的形成。