PDF(Pubmed)
Abstract：
We have previously shown that unconventional myosin VI (MVI), a unique actin-based motor protein, shuttles between the cytoplasm and nucleus in neurosecretory PC12 cells in a stimulation-dependent manner and interacts with numerous proteins involved in nuclear processes. Among the identified potential MVI partners was nucleolin, a major nucleolar protein implicated in rRNA processing and ribosome assembly. Several other nucleolar proteins such as fibrillarin, UBF (upstream binding factor), and B23 (also termed nucleophosmin) have been shown to interact with MVI. A bioinformatics tool predicted the presence of the nucleolar localization signal (NoLS) within the MVI globular tail domain, and immunostaining confirmed the presence of MVI within the nucleolus. Depletion of MVI, previously shown to impair PC12 cell proliferation and motility, caused disorganization of the nucleolus and rough endoplasmic reticulum (rER). However, lack of MVI does not affect nucleolar transcription. In light of these data, we propose that MVI is important for nucleolar and ribosome maintenance but not for RNA polymerase 1-related transcription.
摘要：
我们之前已经表明，非常规肌球蛋白VI(MVI)，一种独特的基于肌动蛋白的运动蛋白，神经分泌PC12细胞的细胞质和细胞核之间以刺激依赖性方式穿梭，并与参与核过程的许多蛋白质相互作用。在确定的潜在MVI合作伙伴是核仁素，与rRNA加工和核糖体组装有关的主要核仁蛋白。其他几种核仁蛋白，如纤维蛋白，UBF(上游结合因子)，和B23(也称为核磷蛋白)已显示与MVI相互作用。生物信息学工具预测了MVI球状尾域中核仁定位信号（NoLS）的存在，免疫染色证实核仁内存在MVI。MVI耗尽,先前显示会损害PC12细胞的增殖和运动，引起核仁和粗面内质网（rER）的解体。然而,缺乏MVI不影响核仁转录。根据这些数据,我们认为MVI对核仁和核糖体的维持很重要，但对RNA聚合酶1相关的转录不重要。
