Yeh Ting-Yu, Chuang Jen-Zen, Sung Ching-Hwa
Department of Ophthalmology, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA.
J Cell Sci. 2005 Aug 1;118(Pt 15):3431-43. doi: 10.1242/jcs.02472.
Cytoplasmic dynein is a motor protein complex involved in microtubule-based cargo movement. Previous biochemical evidence suggests that dynein light chain subunits also exist outside the dynein complex. Here we show that the dynein light chain rp3 is present in both the cytoplasm and the nucleus. Nuclear rp3 binds to and assembles with the transcription factor SATB1 at nuclear matrix-associated structures. Dynein intermediate chain was also detected in the nucleus, but it was dispensable for the rp3-SATB1 interaction. SATB1 facilitates the nuclear localization of rp3, whereas rp3 and dynein motor activity are not essential for nuclear accumulation of SATB1. The nuclear rp3-SATB1 protein complex is assembled with a DNA element of the matrix attachment region of the Bcl2 gene. Finally, rp3 is involved in SATB1-mediated gene repression of Bcl2. Our data provide evidence that dynein subunit rp3 has functions independent of the dynein motor.
胞质动力蛋白是一种参与基于微管的货物运输的马达蛋白复合体。先前的生化证据表明，动力蛋白轻链亚基也存在于动力蛋白复合体外。在这里，我们表明动力蛋白轻链rp3存在于细胞质和细胞核中。核rp3在与核基质相关的结构上与转录因子SATB1结合并组装。在细胞核中也检测到动力蛋白中间链，但它对于rp3-SATB1相互作用是可有可无的。SATB1促进rp3的核定位，而rp3和动力蛋白的运动活性对于SATB1的核积累不是必需的。核rp3-SATB1蛋白复合体与Bcl2基因的基质附着区域的DNA元件组装在一起。最后，rp3参与SATB1介导的Bcl2基因抑制。我们的数据提供了证据，表明动力蛋白亚基rp3具有独立于动力蛋白马达的功能。
