African swine fever virus A238L inhibitor of NF-κB and of calcineurin phosphatase is imported actively into the nucleus and exported by a CRM1-mediated pathway
This study examined nuclear and cytoplasmic shuttling of the African swine fever virus (ASFV) A238L protein, which is an inhibitor of NF-κB and of calcineurin phosphatase. The results showed that the protein was present in both the nucleus and the cytoplasm in ASFV-infected cells and that the higher molecular mass 32 kDa form of the A238L protein was the predominant nuclear form, which accumulated later in infection. In contrast, both the 28 and 32 kDa forms of the A238L protein were present in the cytoplasm. The A238L protein was actively imported into the nucleus and exported by a CRM1-mediated pathway, although a pool of the protein remained in the cytoplasm and did not enter the nucleus. By using a recombinant ASFV from which the A238L gene had been deleted, it was shown that expression of A238L did not inhibit nuclear import of the NF-κB p50 or p65 subunit and did not inhibit nuclear export of p65 by a CRM1-mediated pathway. The results were consistent with a model in which A238L functions within both the nucleus and the cytoplasm.
AubaredaA.,
MuleroM. C.,
Pérez-RibaM.2006; Functional characterization of the calcipressin motif that suppresses calcineurin-mediated NFAT-dependent cytokine gene expression in human T cells. Cell Signal 18:1430–1438[CrossRef]
Camus-BouclainvilleC.,
FietteL.,
BouchihaS.,
PignoletA.,
CounorD.,
FilipeU.,
GelfiJ.,
Messud-PetitF.2004; A virulence factor of myxoma virus colocalizes with NF- κ B in the nucleus and interferes with inflammation. J Virol 78:2510–2516[CrossRef]
DixonL. K.,
EscribanoJ. M.,
MartinsC.,
RockD. L.,
SalasM. L.,
WilkinsonP. J.2005; Asfarviridae. In Virus Taxonomy: Eighth Report of the International Committee on Taxonomy of Viruses pp 135–143 Edited by
FauquetC. M.,
MayoM. A.,
ManiloffJ.,
DesselbergerU.,
BallL. A.
London: Elsevier/Academic Press;
HortonP.,
ParkK.-J.,
ObayashiT.,
NakaiK.2006Protein Subcellular Localization Prediction with WoLF PSORT . Proceedings of the 4th Annual Asia Pacific Bioinformatics Conference APBC06 Taipei, Taiwan: pp 39–48
HuangT. T.,
MiyamotoS.2001; Postrepression activation of NF- κ B requires the amino-terminal nuclear export signal specific to I κ B α
. Mol Cell Biol 21:4737–4747[CrossRef]
HuangT. T.,
KudoN.,
YoshidaM.,
MiyamotoS.2000; A nuclear export signal in the N-terminal regulatory domain of I κ B α controls cytoplasmic localization of inactive NF- κ B/I κ B α complexes. Proc Natl Acad Sci U S A 97:1014–1019[CrossRef]
HuxfordT.,
HuangD.-B.,
MalekS.,
GhoshG.1998; The crystal structure of the I κ B α /NF- κ B complex reveals mechanisms of NF- κ B inactivation. Cell 95:759–770[CrossRef]
JohnsonC.,
Van AntwerpD.,
HopeT. J.1999; An N-terminal nuclear export signal is required for the nucleocytoplasmic shuttling of I κ B α
. EMBO J 18:6682–6693[CrossRef]
KangK.-H.,
LeeK.-H.,
KimM.-Y.,
ChoiK.-H.2001; Caspase-3-mediated cleavage of the NF- κ B subunit p65 at the NH2 terminus potentiates naphthoquinone analog-induced apoptosis. J Biol Chem 276:24638–24644[CrossRef]
LiH.,
RaoA. J.,
HoganP. G.2004; Structural delineation of the calcineurin–NFAT interaction and its parallels to PP1 targeting interactions. J Mol Biol 342:1659–1674[CrossRef]
MalekS.,
HuxfordT.,
GhoshG.1998; I κ B α functions through direct contacts with the nuclear localization signals and the DNA binding sequences of NF- κ B. J Biol Chem 273:25427–25435[CrossRef]
MalekS.,
ChenY.,
HuxfordT.,
GhoshG.2001; I κ B β , but not I κ B α , functions as a classical cytoplasmic inhibitor of NF- κ B dimers by masking both NF- κ B nuclear localization sequences in resting cells. J Biol Chem 276:45225–45235[CrossRef]
MalekS.,
HuangD.-B.,
HuxfordT.,
GhoshS.,
GhoshG.2003; X-ray crystal structure of an I κ B β center dot NF- κ B p65 homodimer complex. J Biol Chem 278:23094–23100[CrossRef]
MiskinJ. E.,
AbramsC. C.,
GoatleyL. C.,
DixonL. K.1998; A viral mechanism for inhibition of the cellular phosphatase calcineurin. Science 281:562–565[CrossRef]
MiskinJ. E.,
AbramsC. C.,
DixonL. K.2000; African swine fever virus protein A238L interacts with the cellular phosphatase calcineurin via a binding domain similar to that of NFAT. J Virol 74:9412–9420[CrossRef]
NeilanJ. G.,
LuZ.,
KutishG. F.,
ZsakL.,
LewisT. L.,
RockD. L.1997; A conserved African swine fever virus I kappa B homolog, 5EL, is nonessential for growth in vitro and virulence in domestic swine. Virology 235:377–385[CrossRef]
PowellP. P.,
DixonL. K.,
ParkhouseR. M. E.1996; An I κ B homolog encoded by African swine fever virus provides a novel mechanism for downregulation of proinflammatory cytokine responses in host macrophages. J Virol 70:8527–8533
RevillaY.,
CallejoM.,
RodríguezJ. M.,
CulebrasE.,
NogalM. L.,
SalasM. L.,
ViñuelaE.,
FresnoM.1998; Inhibition of nuclear factor κ B activation by a virus-encoded I κ B-like protein. J Biol Chem 273:5405–5411[CrossRef]
ScottE. S.,
MalcomberS.,
O'HareP.2001; Nuclear translocation and activation of the transcription factor NFAT is blocked by herpes simplex virus infection. J Virol 75:9955–9965[CrossRef]
TaitS. W. G.,
ReidE. B.,
GreavesD. R.,
WilemanT. E.,
PowellP. P.2000; Mechanism of inactivation of NF- κ B by a viral homologue of I κ B α : signal-induced release of I κ B α results in binding of the viral homologue to NF- κ B. J Biol Chem 275:34656–34664[CrossRef]
YamamotoM.,
YamazakiS.,
UematsuS.,
SatoS.,
HemmiH.,
HoshinoK.,
KaishoT.,
KuwataH.,
TakeuchiO.other authors2004; Regulation of Toll/IL-1-receptor-mediated gene expression by the inducible nuclear protein I κ B ζ
. Nature 430:218–222[CrossRef]
YamazakiS.,
MutaT.,
TakeshigeK.2001; A novel I κ B protein, I κ B ζ , induced by proinflammatory stimuli, negatively regulates nuclear factor- κ B in the nuclei. J Biol Chem 276:27657–27662[CrossRef]
African swine fever virus A238L inhibitor of NF-κB and of calcineurin phosphatase is imported actively into the nucleus and exported by a CRM1-mediated pathway