Coordinated Dynamics of RNA Splicing Speckles in the Nucleus.
Despite being densely packed with chromatin, nuclear bodies and a nucleoskeletal network, the nucleus is a remarkably dynamic organelle. Chromatin loops form and relax, RNA transcripts and transcription factors move diffusively, and nuclear bodies move. We show here that RNA splicing speckled domains (splicing speckles) fluctuate in constrained nuclear volumes and remodel their shapes. Small speckles move in a directed way toward larger speckles with which they fuse. This directed movement is reduced upon decreasing cellular ATP levels or inhibiting RNA polymerase II activity. The random movement of speckles is reduced upon decreasing cellular ATP levels, moderately reduced after inhibition of SWI/SNF chromatin remodeling and modestly increased upon inhibiting RNA polymerase II activity. To define the paths through which speckles can translocate in the nucleus, we generated a pressure gradient to create flows in the nucleus. In response to the pressure gradient, speckles moved along curvilinear paths in the nucleus. Collectively, our results demonstrate a new type of ATP-dependent motion in the nucleus. We present a model where recycling splicing factors return as part of small sub-speckles from distal sites of RNA processing to larger splicing speckles by a directed ATP-driven mechanism through interchromatin spaces.
Department of Chemical Engineering, University of Florida, Gainesville, Florida.
Qiao
Q
Zhang
Department of Cellular and Tissue Imaging, Perkin Elmer Inc., Waltham, Massachusetts.
Krishna P
KP
Kota
Department of Chemical Engineering, University of Florida, Gainesville, Florida.
Samer G
SG
Alam
Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts.
Jeffrey A
JA
Nickerson
Department of Chemical Engineering, University of Florida, Gainesville, Florida.
Richard B
RB
Dickinson
Department of Chemical Engineering, University of Florida, Gainesville, Florida.
Tanmay P
TP
Lele
D000255:Adenosine Triphosphate / Q000378:metabolism; D034961:Antigens, Nuclear / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D042361:Mammary Glands, Human / Q000166:cytology / Q000378:metabolism*; D008954:Models, Biological; D034521:Nuclear Matrix-Associated Proteins / Q000235:genetics / Q000378:metabolism; D011312:Pressure; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012319:RNA Polymerase II / Q000378:metabolism; D012326:RNA Splicing; D034443:RNA Transport; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
D034961:Antigens, Nuclear; D034521:Nuclear Matrix-Associated Proteins; D016601:RNA-Binding Proteins; C111710:SRRM1 protein, human; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D012313:RNA; D000255:Adenosine Triphosphate; D012319:RNA Polymerase II