Nuclear pore complexes form immobile networks and have a very low turnover in live mammalian cells.
The nuclear pore complex (NPC) and its relationship to the nuclear envelope (NE) was characterized in living cells using POM121-green fluorescent protein (GFP) and GFP-Nup153, and GFP-lamin B1. No independent movement of single pore complexes was found within the plane of the NE in interphase. Only large arrays of NPCs moved slowly and synchronously during global changes in nuclear shape, strongly suggesting mechanical connections which form an NPC network. The nuclear lamina exhibited identical movements. NPC turnover measured by fluorescence recovery after photobleaching of POM121 was less than once per cell cycle. Nup153 association with NPCs was dynamic and turnover of this nucleoporin was three orders of magnitude faster. Overexpression of both nucleoporins induced the formation of annulate lamellae (AL) in the endoplasmic reticulum (ER). Turnover of AL pore complexes was much higher than in the NE (once every 2.5 min). During mitosis, POM121 and Nup153 were completely dispersed and mobile in the ER (POM121) or cytosol (Nup153) in metaphase, and rapidly redistributed to an immobilized pool around chromatin in late anaphase. Assembly and immobilization of both nucleoporins occurred before detectable recruitment of lamin B1, which is thus unlikely to mediate initiation of NPC assembly at the end of mitosis.
Daigle
N
N
European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
Beaudouin
J
J
Hartnell
L
L
Imreh
G
G
Hallberg
E
E
Lippincott-Schwartz
J
J
Ellenberg
J
J
D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D034921:Lamin Type B; D034882:Lamins; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008938:Mitosis; D022022:Nuclear Pore / Q000737:chemistry* / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus
D034921:Lamin Type B; D034882:Lamins; D008164:Luminescent Proteins; D008565:Membrane Proteins; C079377:NUP153 protein, human; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; C513083:Nup153 protein, rat; C082264:Pom121 protein, rat; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D004247:DNA