Cofactor requirements for nuclear export of Rev response element (RRE)- and constitutive transport element (CTE)-containing retroviral RNAs. An unexpected role for actin.
Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the export receptor CRM1/exportin1. However, additional protein factors interacting with leucine-rich NESs have been described. Here, we investigate human immunodeficiency virus type 1 (HIV-1) Rev-mediated nuclear export and Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE)-mediated nuclear export in microinjected Xenopus laevis oocytes. We show that eukaryotic initiation factor 5A (eIF-5A) is essential for Rev and Rev-mediated viral RNA export, but not for nuclear export of CTE RNA. In vitro binding studies demonstrate that eIF-5A is required for efficient interaction of Rev-NES with CRM1/exportin1 and that eIF-5A interacts with the nucleoporins CAN/nup214, nup153, nup98, and nup62. Quite unexpectedly, nuclear actin was also identified as an eIF-5A binding protein. We show that actin is associated with the nucleoplasmic filaments of nuclear pore complexes and is critically involved in export processes. Finally, actin- and energy-dependent nuclear export of HIV-1 Rev is reconstituted by using a novel in vitro egg extract system. In summary, our data provide evidence that actin plays an important functional role in nuclear export not only of retroviral RNAs but also of host proteins such as protein kinase inhibitor (PKI).
Department of Cell and Developmental Biology, Biocenter of the University of Würzburg, D-97074 Würzburg, Germany.
W
W
Hofmann
B
B
Reichart
A
A
Ewald
E
E
Müller
I
I
Schmitt
R H
RH
Stauber
F
F
Lottspeich
B M
BM
Jockusch
U
U
Scheer
J
J
Hauber
M C
MC
Dabauvalle
D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D015694:Gene Products, rev / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D016093:Mason-Pfizer monkey virus / Q000235:genetics; D013058:Mass Spectrometry; D008845:Microinjections; D016253:Microscopy, Immunoelectron; D009154:Mutation; D009685:Nuclear Envelope / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D015530:Nuclear Matrix / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D009865:Oocytes / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D014982:Xenopus laevis; D054321:rev Gene Products, Human Immunodeficiency Virus; D000097574:Eukaryotic Translation Initiation Factor 5A
D000199:Actins; D002352:Carrier Proteins; D015694:Gene Products, rev; D047908:Intracellular Signaling Peptides and Proteins; D010448:Peptide Initiation Factors; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D054321:rev Gene Products, Human Immunodeficiency Virus; D000097574:Eukaryotic Translation Initiation Factor 5A; C015482:protein kinase modulator