Stavreva Diana A, Kawasaki Miyuki, Dundr Miroslav, Koberna Karel, Müller Waltraud G, Tsujimura-Takahashi Teruko, Komatsu Wataru, Hayano Toshiya, Isobe Toshiaki, Raska Ivan, Misteli Tom, Takahashi Nobuhiro, McNally James G
Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research [corrected] National Cancer Institute, Bethesda, MD 20892, USA.
Mol Cell Biol. 2006 Jul;26(13):5131-45. doi: 10.1128/MCB.02227-05.
We have investigated the possible involvement of the ubiquitin-proteasome system (UPS) in ribosome biogenesis. We find by immunofluorescence that ubiquitin is present within nucleoli and also demonstrate by immunoprecipitation that complexes associated with pre-rRNA processing factors are ubiquitinated. Using short proteasome inhibition treatments, we show by fluorescence microscopy that nucleolar morphology is disrupted for some but not all factors involved in ribosome biogenesis. Interference with proteasome degradation also induces the accumulation of 90S preribosomes, alters the dynamic properties of a number of processing factors, slows the release of mature rRNA from the nucleolus, and leads to the depletion of 18S and 28S rRNAs. Together, these results suggest that the UPS is probably involved at many steps during ribosome biogenesis, including the maturation of the 90S preribosome.
我们研究了泛素-蛋白酶体系统（UPS）在核糖体生物合成中可能发挥的作用。通过免疫荧光我们发现核仁中存在泛素，并且通过免疫沉淀也证明与前体rRNA加工因子相关的复合物被泛素化。使用短期蛋白酶体抑制处理，我们通过荧光显微镜观察到，对于核糖体生物合成中涉及的一些但并非所有因子，核仁形态受到破坏。对蛋白酶体降解的干扰还会诱导90S前核糖体的积累，改变许多加工因子的动态特性，减缓成熟rRNA从核仁中的释放，并导致18S和28S rRNA的消耗。总之，这些结果表明UPS可能在核糖体生物合成的多个步骤中发挥作用，包括90S前核糖体的成熟。
