Fox Archa H, Bond Charles S, Lamond Angus I
Division of Gene Regulation and Expression, Wellcome Trust Biocentre, University of Dundee, Dundee DD1 5EH, United Kingdom.
Mol Biol Cell. 2005 Nov;16(11):5304-15. doi: 10.1091/mbc.e05-06-0587. Epub 2005 Sep 7.
P54nrb is a protein implicated in multiple nuclear processes whose specific functions may correlate with its presence at different nuclear locations. Here we characterize paraspeckles, a subnuclear domain containing p54nrb and other RNA-binding proteins including PSP1, a protein with sequence similarity to p54nrb that acts as a marker for paraspeckles. We show that PSP1 interacts in vivo with a subset of the total cellular pool of p54nrb. We map the domain within PSP1 that is mediating this interaction and show it is required for the correct localization of PSP1 to paraspeckles. This interaction is necessary but not sufficient for paraspeckle targeting by PSP1, which also requires an RRM capable of RNA binding. Blocking the reinitiation of RNA Pol II transcription at the end of mitosis with DRB prevents paraspeckle formation, which recommences after removal of DRB, indicating that paraspeckle formation is dependent on RNA Polymerase II transcription. Thus paraspeckles are the sites where a subset of the total cellular pool of p54nrb is targeted in a RNA Polymerase II-dependent manner.
P54nrb是一种涉及多种核过程的蛋白质，其特定功能可能与其在不同核位置的存在相关。在这里，我们对旁斑进行了表征，旁斑是一种包含p54nrb和其他RNA结合蛋白（包括PSP1）的亚核结构域，PSP1是一种与p54nrb序列相似的蛋白质，可作为旁斑的标志物。我们表明，PSP1在体内与p54nrb总细胞池的一个子集相互作用。我们绘制了PSP1中介导这种相互作用的结构域，并表明它是PSP1正确定位于旁斑所必需的。这种相互作用对于PSP1靶向旁斑是必要的，但不是充分的，PSP1还需要一个能够结合RNA的RRM。用DRB阻断有丝分裂末期RNA Pol II转录的重新起始可防止旁斑形成，在去除DRB后旁斑形成重新开始，这表明旁斑形成依赖于RNA聚合酶II转录。因此，旁斑是以RNA聚合酶II依赖的方式靶向p54nrb总细胞池一个子集的位点。
