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

Abstract

Human cells treated with interferon synthesize two proteins that exhibit high homology to murine Mxl protein, which has previously been identffied as the mediator of interferon-induced cellular resistance of mouse cells against influenza viruses. Using murine Mxl 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-a) Influenza viruses are important human pathogens (35), and one might therefore expect that humans possess a very efficient influenza virus defense system. During the course of viral infections, including influenza virus infections, interferons (IFNs) are synthesized which, in turn, induce an antiviral state in cells surrounding the initial site of virus replication. It is believed that IFNs thus help to limit virus spread and permit the immune system to destroy the invading virus without causing severe tissue damage. The beneficial role of IFNs in host defense against many viruses has been documented in animal model systems (see reference 7 for a review), suggesting that IFN may play a similar role in humans. From an experimental mouse model of influenza virus resistance, we have concluded that IFN exerts its protective effect through the activation of a cellular resistance gene, designated Mx (see reference 30 for a review). Exposure of mouse cells to IFN induces the synthesis of the 72-kilodalton (kDa) Mxl protein, which, in turn, is capable of selectively blocking the multiplication of influenza viruses (1, 21, 31). The molecular mechanism principally responsible for the IFN-mediated inhibition of influenza virus multiplication is not yet resolved (16,20,25).Evidence in favor of a similar influenza virus defense system in humans includes the observations that IFN can block influenza virus multiplication very efficiently in cultured human fibroblasts (10) and that IFN treatment causes the accumulation of an Mx-related protein in these cells (11,29). This Mx-related human protein has an apparent molecular mass of about 78 kDa, and, unlike murine Mxl protein, it accumulates in the cell cytoplasm rather than the nucleus. Although available data are compatible with the view that the Mx-related human protein plays a role in defense against * Corresponding author. influenza virus, no direct experimental evidence supporting this notion has yet been presented.One approach to the elucidation of the physiological role of Mx-like proteins of humans is to molecularly clone the human Mx cDNAs and then to express them in transfected cells and to test such cells for newly acquired functions, in particular influenza virus resistance. In this paper we report the first step toward this goal, the isolation and characterization of two Mx-related human cDNAs. We show that the corresponding mRNAs originate from two distinct human Mx genes; the expression of both genes is stimulated by IFN-a, IFN-P, Newcastle disease virus (NDV), and, to a lesser extent...

High density oligonucleotide array analysis of interferon-α2a sensitivity and transcriptional response in melanoma cells

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Effects of allelic variations in the human myxovirus resistance protein A on its antiviral activity

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GTPase properties of the interferon‐induced human guanylate‐binding protein 2

“…pHis-hGbp2, which codes for a histidine-tagged variant of hGBP2, was constructed by replacing the coding sequence of hGBP1 for that of hGBP2. The appropriate hGBP2 cDNA fragment was generated by PCR from a cDNA library derived from interferoninduced human fibroblasts [11] using the primer 5'ACTTAG-GATCCGCTCCAGAGATCAACTTG3' which carries a BamHI restriction site and which corresponds to positions 160-177 of the RACE hGBP2 cDNA clone (Fig. 1A) and the primer 5'ATT-GAACGTCGACGGCAAATTTTGCTCCTTGGACT3' which carries a Sail restriction site and which corresponds to positions 1784-1763 of the previously characterized hGBP2 cDNA [4].…”