Heterogeneity of poly(I).poly(C)-induced human fibroblast interferon mRNA species

Abstract

Three classes of human interferons (IFNs) have been defined on the basis of their immunological properties: the 'Le' or 'alpha' IFN, mainly derived from leukocyte or lymphoblastoid cells; the 'F' or 'beta' IFN, mainly derived from fibroblast cultures; and the 'T', 'immune' or 'gamma' IFN, mainly derived from mitogen- or antigen-stimulated lymphoid cells. Whereas several individual species of Le IFN have been purified to homogeneity, it is generally considered that F IFN represents a single protein. Thus current efforts to clone human fibroblast IFN mRNA sequences are based on the observation that F IFN mRNA sediments in sucrose gradients as a single RNA species of size corresponding to 12-14 S (refs 7-10). We show here, using gel electrohporesis of mRNA, that two populations of translationally active human fibroblast IFN mRNA molecules exist--an abundant '14 S' species and a scarce '11 S' species. Microinjection of either species of mRNA into Xenopus oocytes leads to the synthesis of biologically active F-type human IFN. These data agree with and complement recent RNA hybridization studies of Weissenbach et al.

Analysis of interferon mRNA in human fibroblast cells induced to produce interferon.

“…The mRNA is longer than the cloned cDNA (860 nucleotides) (14-16) due to the presence ofpoly(A) residues; an average length ofpoly(A) in most eukaryotic mRNAs is 250 nucleotides (24), which is in agreement with our findings. Others have estimated the mRNA to be 850-950 nucleotides long (19,20 our results do not confirm observations of Sagar et al (25), who found that / mRNA induced in Namalva cells is significantly larger than that in fibroblasts.…”

“…1). Because multiple forms of immunologically crossreacting / interferon were previously found (19,20), the pooled fractions were microinjected into Xenopus oocytes and the newly synthesized proteins were labeled with [3S]methionine. Interferon was identified by selective immunoprecipitation with antiserum to / interferon and analyzed by one-and two-dimensionalgel electrophoresis.…”

Induction and regulation of the 26-kDa protein in the absence of synthesis of beta-interferon mRNA in human cells

“…This protein can be precipitated with a partially purified antiserum directed against partially purified HuIFN-P. After cloning the corresponding cDNA [6] they could purify this mRNA on its cloned cDNA and translate it into a 23 -26-kDa-protein with antiviral and (2'-5')(A),, synthetase-inducing activities. This protein was named IFN-P, and is probably distinct [7] from the IFN-P, described by Sehgal et al [8,9]. We have also observed such a 26-kDa-protein mRNA in preparations of mRNA from poly (1).…”

Anti-beta-interferon antibodies inhibit the increased expression of HLA-B7 mRNA in tumor necrosis factor-treated human fibroblasts: structural studies of the beta 2 interferon involved.

“…The IFN-/32 gene is located on human chromosome 7 (9), and cloned IFN-/82 genomic DNA transfected into rodent cells yields cells that can be induced by poly(I)-poly(C) to produce biologically active human IFN-P2 (7,8). Although IFN-/31 and -/32 mRNAs do not cross-hybridize with the respective heterologous IFN-/3 cDNA probes, polyclonal and monoclonal antisera raised against IFN-,81 neutralize the anti-viral activity of IFN-P32 (3)(4)(5)(6)(7)(8)(9). IFN-f-related DNA has also been localized on human chromosomes 2 and 4 (14,15).…”

“…Multiple distinct ,3 interferon (IFN-,B) genes are induced by poly(I)-poly(C) in human fibroblasts (3)(4)(5)(6)(7)(8)(9). The IFN-,/1 gene has been cloned and expressed as biologically active recombinant IFN-,81 (reviewed in refs.…”