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P Staeheli

Publications and source records attributed to P Staeheli.

At least 91 records · Page 5Linked to original sources
PubMed1991

Inhibition of vesicular stomatitis virus mRNA synthesis by human MxA protein.

The interferon-induced human MxA protein inhibits the multiplication of influenza virus and vesicular stomatitis virus (VSV) by an unknown mechanism. Here we show that MxA protein interferes with VSV mRNA synthesis. Transfected Swiss 3T3 mouse cells constitutively expressing MxA protein and control cells were infected with VSV, and viral RNA and protein synthesis was monitored. Viral macromolecules were very abundant in control cells at 4 h postinfection, whereas the pools of VSV proteins and RNAs were more than 50-fold reduced in cells expressing MxA. To determine whether MxA inhibited VSV primary transcription, we infected the cells in the presence of the protein synthesis inhibitor cycloheximide and measured the pools of the five viral mRNAs at 4 h postinfection. VSV L mRNA concentration was more than 20-fold reduced, VSV G mRNA concentration was about 10-fold reduced, and the other viral mRNAs were three- to fivefold less abundant in MxA-expressing cells than in control cells. Our results thus indicate that MxA interferes with normal VSV mRNA synthesis either directly by inhibiting the activity of the viral polymerase complex or indirectly by reducing the stability of the VSV mRNAs.

Animals↗
PubMed1991

Interferon-induced guanylate-binding proteins lack an N(T)KXD consensus motif and bind GMP in addition to GDP and GTP.

The primary structures of interferon (IFN)-induced guanylate-binding proteins (GBPs) were deduced from cloned human and murine cDNAs. These proteins contained only two of the three sequence motifs typically found in GTP/GDP-binding proteins. The N(T)KXD motif, which is believed to confer guanine specificity in other nucleotide-binding proteins, was absent. Nevertheless, the IFN-induced GBPs exhibited a high degree of selectivity for binding to agarose-immobilized guanine nucleotides. An interesting feature of IFN-induced GBPs is that they strongly bound to GMP agarose in addition to GDP and GTP agaroses but failed to bind to ATP agarose and all other nucleotide agaroses tested. Both GTP and GMP, but not ATP, competed for binding of murine GBP-1 to agarose-immobilized GMP. The IFN-induced GBPs thus define a distinct novel family of proteins with GTP-binding activity. We further demonstrate that human and murine cells contain at least two genes encoding IFN-induced GBPs. The cloned murine cDNA codes for GBP-1, an IFN-induced protein previously shown to be absent from mice of Gbp-1b genotype.

Amino Acid Sequence↗
PubMed1990

Nuclear myxovirus-resistance protein Mx is a minor histocompatibility antigen.

Minor histocompatibility antigens (MiHAgs) cause slow-to-rapid organ transplant rejection by immunocompetent hosts and mild-to-severe graft-versus-host reactions in immunosuppressed hosts. MiHAgs are allelic forms of major histocompatibility complex (MHC) class I-restricted self-antigens recognized by cytotoxic T cells and usually are defined immunogenetically. Although structurally not identified as yet, it is assumed that MiHAgs are internal cell antigens that are processed and then presented by MHC class I proteins similar to viral antigens. To define a MiHAg both molecularly and functionally, we took advantage of the allelic difference of the structurally characterized intracellular myxovirus-resistance protein (Mx) and investigated its antigenicity. Skin grafts from congenic Mx+ mice carrying the functional Mx1 gene were rejected by mice lacking a functional Mx1 gene (Mx- mice). In parallel, cytotoxic MHC class I-restricted effector T cells specific for Mx protein and the H-2Kk antigen (but not for several other allelic H-2 antigens) were strongly induced in Mx- mice immunized with spleen cells from interferon-treated Mx+ mice. These data show that allelic forms of cell internal proteins presented by MHC class I may act as MiHAgs.

Alleles↗
PubMed1990

Resistance to influenza virus and vesicular stomatitis virus conferred by expression of human MxA protein.

MxA and MxB are interferon-induced proteins of human cells and are related to the murine protein Mx1, which confers selective resistance to influenza virus. In contrast to the nuclear murine protein Mx1, MxA and MxB are located in the cytoplasm, and their role in the interferon-induced antiviral state was unknown. In this report we show that transfected cell lines expressing MxA acquired a high degree of resistance to influenza A virus. Surprisingly, MxA also conferred resistance to vesicular stomatitis virus. Expression of MxA in transfected 3T3 cells had no effect on the multiplication of two picornaviruses, a togavirus, or herpes simplex virus type 1. Treatment of MxA-expressing cells with antibodies to mouse alpha-beta interferon did not abolish the resistance phenotype. The conclusion that resistance to influenza virus and vesicular stomatitis virus was due to the specific action of MxA is further supported by the observation that transfected 3T3 cell lines expressing the related MxB failed to acquire virus resistance.

Animals↗
PubMed1989

cDNA structures and regulation of two interferon-induced human Mx proteins.

Human cells treated with interferon synthesize two proteins that exhibit high homology to murine Mx1 protein, which has previously been identified as the mediator of interferon-induced cellular resistance of mouse cells against influenza viruses. Using murine Mx1 cDNA as a hybridization probe, we have isolated cDNA clones originating from two distinct human Mx genes, designated MxA and MxB. In human fibroblasts, expression of MxA and MxB is strongly induced by alpha interferon (IFN-alpha), IFN-beta, Newcastle disease virus, and, to a much lesser extent, IFN-gamma, MxA and MxB proteins have molecular masses of 76 and 73 kilodaltons, respectively, and their sequences are 63% identical. A comparison of human and mouse Mx proteins revealed that human MxA and mouse Mx2 are the most closely related proteins, showing 77% sequence identity. Near their amino termini, human and mouse Mx proteins contain a block of 53 identical amino acids and additional regions of very high sequence similarity. These conserved sequences are also present in a double-stranded RNA-inducible fish gene, which suggests that they may constitute a functionally important domain of Mx proteins. In contrast to mouse Mx1 protein, which accumulates in the nuclei of IFN-treated mouse cells, the two human Mx proteins both accumulate in the cytoplasm of IFN-treated cells.

Amino Acid Sequence↗
PubMed1989

A double-stranded RNA-inducible fish gene homologous to the murine influenza virus resistance gene Mx.

We cloned and sequenced a 2.35-kilobase EcoRI fragment of genomic DNA from a local freshwater fish (Perca fluviatilis) that strongly hybridized to probes derived from the murine influenza virus resistance gene Mx. The cloned fish DNA contained blocks of sequences related to Mx gene exons 3 to 8, which appeared to represent exons of a bona fide fish gene because they were separated by intron sequences flanked by consensus splice acceptor and donor sites. Injection of double-stranded RNA into the peritoneal cavity of trouts resulted in 5- to 10-fold elevated levels of two liver mRNAs of about 2.0 to 2.5 kilobases in length that hybridized to the cloned genomic DNA. High sequence similarity between this fish gene and the murine Mx gene, identical exon lengths, and similar inducibilities in vivo by double-stranded RNA indicate that we isolated a fragment of a fish Mx gene.

Amino Acid Sequence↗
PubMed1988

A family of interferon-induced Mx-related mRNAs encodes cytoplasmic and nuclear proteins in rat cells.

Mouse Mx protein, an interferon (IFN)-induced nuclear protein, confers selective resistance to influenza virus. We show here that, as with influenza virus-resistant Mx+ mouse embryo cells, influenza virus mRNA accumulation and protein synthesis are strongly inhibited in rat embryo cells treated with IFN-alpha/beta. IFN-alpha/beta induced in rat cells the synthesis of Mx-related mRNAs migrating on Northern (RNA) gels as two bands of about 3.5 and 2.5 kilobases which directed the synthesis of three electrophoretically distinct proteins called rat Mx proteins 1, 2, and 3. The three rat proteins were antigenically related to the mouse Mx protein but differed in molecular weight and intracellular location. Rat Mx protein 1 was found predominantly in the nucleus and, on the basis of several criteria, resembled the nuclear mouse Mx protein. It was induced by IFN-alpha/beta in all 28 inbred rat strains tested. Rat Mx proteins 2 and 3 differed from protein 1 at the carboxy terminus and were predominantly cytoplasmic like the human Mx homolog. Sequence data of partial cDNA clones indicate that three Mx-related genes, rather than one, exist in the rat.

Animals↗
PubMed1988

Influenza virus-susceptible mice carry Mx genes with a large deletion or a nonsense mutation.

The interferon-regulated mouse Mx gene encodes the 72-kilodalton nuclear Mx protein that selectively inhibits influenza virus replication. Mice carrying Mx+ alleles synthesize Mx protein and resist influenza virus infection, whereas mice homozygous for Mx- alleles fail to synthesize Mx protein and, as a consequence, are influenza virus susceptible. Southern blot analysis allowed us to define the following three distinct Mx restriction fragment length polymorphism (RFLP) types among classical inbred strains: RFLP type 1 in the Mx+ strains A2G and SL/NiA, RFLP type 2 in BALB/c and 33 other Mx- strains, and RFLP type 3 in CBA/J and 2 other Mx- strains. cDNA clones of Mx mRNAs from BALB/c and CBA/J cells were isolated, and their sequences were compared with that of the wild-type Mx mRNA of strain A2G. Mx mRNA of BALB/c mice has 424 nucleotides absent from the coding region, resulting in a frame shift and premature termination of Mx protein. The missing sequences correspond exactly to Mx exons 9 through 11. These three exons, together with some flanking intron sequences, are deleted from the genomes of all Mx RFLP type 2 strains. The Mx- phenotype of the Mx RFLP type 3 strain CBA/J is due to a point mutation that converts the lysine codon in position 389 to a termination codon. Mx RFLP type 3 strains have an extra HindIII site which maps to an intron and thus probably does not affect the coding capacity of Mx mRNA. We further show that the Mx mRNA levels in interferon-treated BALB/c and CBA/J cells are about 15-fold lower than in similarly treated Mx+ cells. This is probably due to decreased metabolic stabilities of the mutant mRNAs.

Animals↗
PubMed1988

Identification of a second interferon-regulated murine Mx gene.

The murine influenza virus resistance locus Mx consists of more than one interferon-responsive transcription unit. We isolated clones of the transcripts of a second Mx gene (Mx2) which is closely linked to the well-characterized resistance gene and determined their sequences. Mx2 mRNA is more than 90% identical to Mx1 mRNA in the region corresponding to the amino termini of the encoded proteins. Mx2 mRNAs of mouse strains BALB/c and CBA have open reading frames apparently interrupted by mutations. Interferon-treated cells from strain A2G and other influenza virus-resistant strains failed to express detectable amounts of Mx2 transcripts.

Amino Acid Sequence↗
PubMed1988

Organization of the murine Mx gene and characterization of its interferon- and virus-inducible promoter.

Specific resistance of Mx+ mice to influenza virus is due to the interferon (IFN)-induced protein Mx. The Mx gene consists of 14 exons that are spread over at least 55 kilobase pairs of DNA. Surprisingly, the Mx gene promoter is induced as efficiently by Newcastle disease virus as it is by IFN. The 5' boundary of the region required for maximal induction by both IFN and Newcastle disease virus is located about 140 base pairs upstream of the cap site. This region contains five elements of the type GAAANN, which occurs in all IFN- and virus-inducible promoters. The consensus sequence purine-GAAAN(N/-)GAAA(C/G)-pyrimidine is found in all IFN-inducible promoters.

Amino Acid Sequence↗
PubMed1987

Influenza virus resistance of wild mice: wild-type and mutant Mx alleles occur at comparable frequencies.

The laboratory-reared progeny of wild Mus musculus domesticus from several places in Europe and from California were tested for resistance to experimental infection with influenza viruses and for the ability of their explanted macrophages to synthesize Mx protein in response to type I interferon. About 75% of these mice were resistant to influenza viruses and were able to synthesize Mx protein, as expected for mice carrying the influenza virus resistance allele Mx+ in either homozygous or heterozygous form. Resistance of wild mice was inherited as a single autosomal dominant trait which cosegregated with the ability to synthesize Mx protein. About 25% of the randomly bred wild mice failed to synthesize Mx protein and died after infection with influenza virus, very much like inbred mice homozygous for the Mx- allele. We conclude that Mx+ and Mx- alleles occur at roughly equal frequencies in wild mice and that some selective advantage for heterozygous individuals exists in the wild. This finding raises new questions about the physiological role of the Mx locus.

Animals↗
PubMed1986

Mx protein: constitutive expression in 3T3 cells transformed with cloned Mx cDNA confers selective resistance to influenza virus.

Mx+ mice are much more resistant to influenza virus than Mx- strains. The resistance is mediated by interferon (IFN) alpha/beta. After IFN treatment, Mx+ but not Mx- cells accumulate Mx protein and become specifically resistant to orthomyxoviruses. cDNA encoding Mx protein was cloned and sequenced. Southern analyses indicate that Mx- alleles derive from their Mx+ counterpart by deletions. IFN-treated Mx+ cells contained a 3.5 kb Mx mRNA, while Mx- cells showed only traces of shorter Mx RNA. Mx- cells transformed with Mx cDNA expressed Mx protein constitutively to varying extents; resistance of individual cells to influenza virus correlated with Mx protein expression. Thus, specific resistance to influenza virus in vivo may be attributed to Mx protein expression and is independent of other IFN-mediated effects.

Amino Acid Sequence↗
PubMed1986

Interferon-regulated influenza virus resistance gene Mx is localized on mouse chromosome 16.

Genomic Southern blots of mouse-hamster somatic cell hybrids were analyzed with a probe prepared from a cDNA encoding murine Mx protein, the product of the interferon-regulated influenza virus resistance allele Mx+. Results of this analysis indicate that the Mx gene is located on mouse chromosome 16. In appropriate backcross mice, no linkage was observed between Mx and md, a marker previously mapped close to the centromere of chromosome 16, suggesting a more distal localization of Mx.

Alleles↗
PubMed1986

Transcriptional activation of the mouse Mx gene by type I interferon.

Mouse cells of the Mx+ genotype accumulate Mx mRNA in response to type I interferon (IFN). Nuclear runoff experiments show that IFN stringently regulates Mx gene expression at the level of transcription. Mx mRNA synthesis peaks about 3 h after IFN treatment, and within 5 h, Mx mRNA concentration rises from undetectable levels to about 0.1% of polyadenylated RNA.

Animals↗
PubMed1985

Polyclonal and monoclonal antibodies to the interferon-inducible protein Mx of influenza virus-resistant mice.

Interferon-alpha/beta induces in cells from mice carrying the influenza virus resistance allele Mx+ the synthesis of a unique 75,000-dalton protein (designated here protein Mx) that was not detectable in interferon-treated cells from Mx- mice lacking the resistance allele (Horisberger, M. A., Staeheli, P., and Haller, O. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 1910-1914). We have immunized Mx- BALB/c mice with extracts of interferon-treated cells from congenic Mx+ BALB X A2G-Mx mice. Resulting hyperimmune sera immunoprecipitated a single interferon-inducible 75,000-dalton protein of Mx+ embryo cells. Sera did not react with any interferon-inducible protein of Mx- cells. Synthesis of the immunoprecipitable 75,000-dalton protein Mx was induced by interferon-alpha/beta but not by interferon-gamma in Mx+ cells of diverse genetic backgrounds. Monoclonal antibodies to protein Mx were selected in similar immunoprecipitation assays. One discrete in vitro translation product of relevant mRNA reacted with polyclonal and monoclonal antibodies and was indistinguishable from in vivo synthesized protein Mx.

Animals↗