Live cell imaging and electron microscopy reveal dynamic processes of BAF-directed nuclear envelope assembly.
Assembly of the nuclear envelope (NE) in telophase is essential for higher eukaryotic cells to re-establish a functional nucleus. Time-lapse, FRAP and FRET analyses in human cells showed that barrier-to-autointegration factor (BAF), a DNA-binding protein, assembled first at the distinct ;core' region of the telophase chromosome and formed an immobile complex by directly binding with other core-localizing NE proteins, such as lamin A and emerin. Correlative light and electron microscopy after live cell imaging, further showed that BAF formed an electron-dense structure on the chromosome surface of the core, close to spindle microtubules (MTs) prior to the attachment of precursor NE membranes, suggesting that MTs may mediate core assembly of BAF. Disruption of the spindle MTs consistently abolished BAF accumulation at the core. In addition, RNAi of BAF eliminated the core assembly of lamin A and emerin, caused abnormal cytoplasmic accumulation of precursor nuclear membranes and resulted in a significant delay of NE assembly. These results suggest that the MT-mediated BAF accumulation at the core facilitates NE assembly at the end of mitosis.
Haraguchi
Tokuko
T
CREST Research Project, Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, Japan. tokuko@nict.go.jp
Kojidani
Tomoko
T
Koujin
Takako
T
Shimi
Takeshi
T
Osakada
Hiroko
H
Mori
Chie
C
Yamamoto
Akitsugu
A
Hiraoka
Yasushi
Y
D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D022082:Cellular Structures / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D034904:Lamin Type A / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D009685:Nuclear Envelope / Q000378:metabolism / Q000648:ultrastructure*; D009687:Nuclear Proteins / Q000032:analysis* / Q000378:metabolism*; D034622:RNA Interference; D013692:Telophase
C501959:BANF1 protein, human; D002843:Chromatin; D004268:DNA-Binding Proteins; D034904:Lamin Type A; D008565:Membrane Proteins; D009687:Nuclear Proteins; C092710:emerin