Association of AUUUA-binding protein with A+U-rich mRNA during nucleo-cytoplasmic transport.
Resealed nuclear envelope (NE) vesicles from rat liver containing entrapped exogenous RNA were used to study the effect of adenosine+uridine binding factor (AUBF), present in cytosolic cell extracts, on ATP-dependent transport of A+U-rich RNA (AU+RNA) and A+U-free RNA (AU-RNA) across the NE. This factor specifically binds to A+U-rich sequences present in the 3' untranslated regions of lymphokine and cytokine mRNAs, containing overlapping AUUUA boxes (granulocyte-macrophage colony stimulating factor, interleukin-3). Addition of AUBF to the extravesicular compartment markedly increased the efflux of the in vitro transcribed, capped and polyadenylated AU+ RNAs. Export of entrapped AU- control RNA, such as beta-globin RNA, was not affected by AUBF, in contrast to chimeric AU+ beta-globin RNA containing the A+U-rich sequence of human interferon-alpha mRNA (6 reiterated AUUUA motifs). Competition experiments revealed that AUBF enhances the affinity of poly(A)-containing AU+ RNAs to the NE poly(A)-binding component (poly(A)-recognizing mRNA carrier p106), and thereby accelerates nuclear export of these RNAs. We could demonstrate that AUBF added to the extravesicular space forms stable complexes with polyadenylated AU+ RNA with relative molecular masses of about 45,000, 62,000 and 70,000 inside the vesicles or during ATP-dependent export. In addition we determined that AUBF may affect mRNA stability by protecting A+U-rich RNA against degradation by trans-acting, nuclear matrix-associated and A+U-specific endoribonuclease V.
Müller
W E
WE
Institut für Physiologische Chemie, Universität, Mainz, Germany.
Slor
H
H
Pfeifer
K
K
Hühn
P
P
Bek
A
A
Orsulic
S
S
Ushijima
H
H
Schröder
H C
HC
D000241:Adenosine; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004722:Endoribonucleases / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D016898:Interferon-alpha / Q000235:genetics; D007377:Interleukin-3 / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism; D015530:Nuclear Matrix / Q000378:metabolism; D010957:Plasmids; D011131:Polyribonucleotides / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins; D051381:Rats; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism; D014158:Transcription, Genetic; D014529:Uridine
D002352:Carrier Proteins; D016898:Interferon-alpha; D007377:Interleukin-3; D011131:Polyribonucleotides; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C076141:adenosine-uridine binding factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D004722:Endoribonucleases; C025115:ribonuclease V; D000241:Adenosine; D014529:Uridine