The interferon-induced murine Mx1 GTPase is a nuclear protein. It specifically inhibits influenza A viruses at the step of primary transcription, a process known to occur in the nucleus of infected cells. However, the exact mechanism of inhibition is still poorly understood. The Mx1 GTPase has previously been shown to accumulate in distinct nuclear dots that are spatially associated with promyelocytic leukaemia protein (PML) nuclear bodies (NBs), but the significance of this association is not known. Here it is reported that, in cells lacking PML and, as a consequence, PML NBs, Mx1 still formed nuclear dots. These dots were indistinguishable from the dots observed in wild-type cells, indicating that intact PML NBs are not required for Mx1 dot formation. Furthermore, Mx1 retained its antiviral activity against influenza A virus in these PML-deficient cells, which were fully permissive for influenza A virus. Nuclear Mx proteins from other species showed a similar subnuclear distribution. This was also the case for the human MxA GTPase when this otherwise cytoplasmic protein was translocated into the nucleus by virtue of a foreign nuclear localization signal. Human MxA and mouse Mx1 do not interact or form heterooligomers. Yet, they co-localized to a large degree when co-expressed in the nucleus. Taken together, these findings suggest that Mx1 dots represent distinct nuclear domains (‘Mx nuclear domains’) that are frequently associated with, but functionally independent of, PML NBs.
AccolaM. A.,
HuangB.,
Al MasriA.,
McNivenM. A.2002; The antiviral dynamin family member, MxA, tubulates lipids and localizes to the smooth endoplasmic reticulum. J Biol Chem 277:21829–21835[CrossRef]
BlondelD.,
RegadT.,
PoissonN.,
PavieB.,
HarperF.,
PandolfiP. P.,
de TheH.,
Chelbi-AlixM. K.2002; Rabies virus P and small P products interact directly with PML and reorganize PML nuclear bodies. Oncogene 21:7957–7970[CrossRef]
BordenK. L.2002; Pondering the promyelocytic leukemia protein (PML) puzzle: possible functions for PML nuclear bodies. Mol Cell Biol 22:5259–5269[CrossRef]
BordenK. L.,
Campbell DwyerE. J.,
SalvatoM. S.1998; An arenavirus RING (zinc-binding) protein binds the oncoprotein promyelocyte leukemia protein (PML) and relocates PML nuclear bodies to the cytoplasm. J Virol 72:758–766
Chelbi-AlixM. K.,
PelicanoL.,
QuignonF.,
KokenM. H.,
VenturiniL.,
StadlerM.,
PavlovicJ.,
DegosL.,
de TheH.1995; Induction of the PML protein by interferons in normal and APL cells. Leukemia 9:2027–2033
Chelbi-AlixM. K.,
QuignonF.,
PelicanoL.,
KokenM. H.,
de TheH.1998; Resistance to virus infection conferred by the interferon-induced promyelocytic leukemia protein. J Virol 72:1043–1051
DerS. D.,
ZhouA.,
WilliamsB. R.,
SilvermanR. H.1998; Identification of genes differentially regulated by interferon alpha, beta, or gamma using oligonucleotide arrays. Proc Natl Acad Sci U S A 95:15623–15628[CrossRef]
DjavaniM.,
RodasJ.,
LukashevichI. S.,
HorejshD.,
PandolfiP. P.,
BordenK. L.,
SalvatoM. S.2001; Role of the promyelocytic leukemia protein PML in the interferon sensitivity of lymphocytic choriomeningitis virus. J Virol 75:6204–6208[CrossRef]
DreidingP.,
StaeheliP.,
HallerO.1985; Interferon-induced protein Mx accumulates in nuclei of mouse cells expressing resistance to influenza viruses. Virology 140:192–196[CrossRef]
EngelhardtO. G.,
UllrichE.,
KochsG.,
HallerO.2001; Interferon-induced antiviral Mx1 GTPase is associated with components of the SUMO-1 system and promyelocytic leukemia protein nuclear bodies. Exp Cell Res 271:286–295[CrossRef]
EngelhardtO. G.,
BoutellC.,
OrrA.,
UllrichE.,
HallerO.,
EverettR. D.2003; The homeodomain-interacting kinase PKM (HIPK-2) modifies ND10 through both its kinase domain and a SUMO-1 interaction motif and alters the posttranslational modification of PML. Exp Cell Res 283:36–50[CrossRef]
FlohrF.,
Schneider-SchauliesS.,
HallerO.,
KochsG.1999; The central interactive region of human MxA GTPase is involved in GTPase activation and interaction with viral target structures. FEBS Lett 463:24–28[CrossRef]
GarberE. A.,
HreniukD. L.,
ScheidelL. M.,
van der PloegL. H.1993; Mutations in murine Mx1: effects on localization and antiviral activity. Virology 194:715–723[CrossRef]
GautierC.,
MehtaliM.,
LatheR.1989; A ubiquitous mammalian expression vector, pHMG, based on a housekeeping gene promoter. Nucleic Acids Res 17:8389[CrossRef]
HallerO.,
ArnheiterH.,
LindenmannJ.1976; Genetically determined resistance to infection by hepatotropic influenza A virus in mice: effect of immunosuppression. Infect Immun 13:844–854
HallerO.,
FreseM.,
RostD.,
NuttallP. A.,
KochsG.1995; Tick-borne thogoto virus infection in mice is inhibited by the orthomyxovirus resistance gene product Mx1. J Virol 69:2596–2601
IshovA. M.,
SotnikovA. G.,
NegorevD.,
VladimirovaO. V.,
NeffN.,
KamitaniT.,
YehE. T.,
StraussJ. F.III,
MaulG. G.1999; PML is critical for ND10 formation and recruits the PML-interacting protein daxx to this nuclear structure when modified by SUMO-1. J Cell Biol 147:221–234[CrossRef]
IsraelA.1979; Preliminary characterization of the particles from productive and abortive infections of L cells by fowl plague virus. Ann Microbiol (Paris) 130B:85–100
KolbE.,
LaineE.,
StrehlerD.,
StaeheliP.1992; Resistance to influenza virus infection of Mx transgenic mice expressing Mx protein under the control of two constitutive promoters. J Virol 66:1709–1716
LindenmannJ.,
DeuelE.,
FanconiS.,
HallerO.1978; Inborn resistance of mice to myxoviruses: macrophages express phenotype in vitro. J Exp Med 147:531–540[CrossRef]
MeierE.,
FahJ.,
GrobM. S.,
EndR.,
StaeheliP.,
HallerO.1988; A family of interferon-induced Mx-related mRNAs encodes cytoplasmic and nuclear proteins in rat cells. J Virol 62:2386–2393
MelenK.,
RonniT.,
BroniB.,
KrugR. M.,
von BonsdorffC. H.,
JulkunenI.1992; Interferon-induced Mx proteins form oligomers and contain a putative leucine zipper. J Biol Chem 267:25898–25907
Nason-BurchenalK.,
GandiniD.,
BottoM.,
AllopennaJ.,
SealeJ. R.,
CrossN. C.,
GoldmanJ. M.,
DmitrovskyE.,
PandolfiP. P.1996; Interferon augments PML and PML/RAR alpha expression in normal myeloid and acute promyelocytic cells and cooperates with all-trans retinoic acid to induce maturation of a retinoid-resistant promyelocytic cell line. Blood 88:3926–3936
NegorevD.,
MaulG. G.2001; Cellular proteins localized at and interacting within ND10/PML nuclear bodies/PODs suggest functions of a nuclear depot. Oncogene 20:7234–7242[CrossRef]
PontenA.,
SickC.,
WeeberM.,
HallerO.,
KochsG.1997; Dominant-negative mutants of human MxA protein: domains in the carboxy-terminal moiety are important for oligomerization and antiviral activity. J Virol 71:2591–2599
RasheedZ. A.,
SaleemA.,
RaveeY.,
PandolfiP. P.,
RubinE. H.2002; The topoisomerase I-binding RING protein, topors, is associated with promyelocytic leukemia nuclear bodies. Exp Cell Res 277:152–160[CrossRef]
RegadT.,
SaibA.,
Lallemand-BreitenbachV.,
PandolfiP. P.,
de TheH.,
Chelbi-AlixM. K.2001; PML mediates the interferon-induced antiviral state against a complex retrovirus via its association with the viral transactivator. EMBO J 20:3495–3505[CrossRef]
StaeheliP.,
GrobR.,
MeierE.,
SutcliffeJ. G.,
HallerO.1988; Influenza virus-susceptible mice carry Mx genes with a large deletion or a nonsense mutation. Mol Cell Biol 8:4518–4523
ToyodaT.,
AsanoY.,
IshihamaA.1995; Role of GTPase activity of murine Mx1 protein in nuclear localization and anti-influenza virus activity. J Gen Virol 76:1867–1869[CrossRef]