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Two interferon mRNAs in human fibroblasts: in vitro translation and Escherichia coli cloning studies
Abstract:
Two mRNA species that produce biologically active interferon were isolated from human fibroblasts and studied by size fractionation and cloning in Escherichia coli plasmid pBR322. The major fibroblast interferon (Hu IFN-beta 1) is coded for by the smaller of the two mRNAs, an 11S species, 900 nucleotides long, which in cell-free systems yields a 20,000 Mr protein. The second interferon mRNA species (Hu IFN-beta 2) is 14S, about 1300 nucleotides long, and codes for another protein of 23,000-26,000 Mr. The two interferon mRNAs do not cross-hybridize. Both are induced by poly(rI.rC), but IFN-beta 2 mRNA is induced to about 10% in cells by cycloheximide treatment alone whereas under these conditions IFN-beta 1 is not induced.
Insights
Researchers identified two distinct messenger RNA (mRNA) types responsible for producing human interferon (IFN). These interferon mRNAs differ in size and do not cross-hybridize, offering insights into interferon gene regulation.
Area of Science:
- Molecular Biology
- Immunology
- Biochemistry
Background:
- Interferons (IFNs) are crucial proteins in the innate immune system, mediating antiviral and antiproliferative responses.
- Understanding the molecular basis of IFN production, including the specific mRNA species involved, is key to developing therapeutic strategies.
Purpose of the Study:
- To isolate and characterize the messenger RNA (mRNA) species responsible for producing biologically active human interferon (IFN) from fibroblasts.
- To investigate the distinct properties and induction patterns of different IFN mRNA species.
Main Methods:
- Size fractionation of mRNA extracted from human fibroblasts.
- Cloning of mRNA species into the Escherichia coli plasmid pBR322.
- Analysis of protein products using cell-free systems and molecular weight determination.
Main Results:
- Two distinct mRNA species, Hu IFN-beta 1 (11S, 900 nucleotides) and Hu IFN-beta 2 (14S, 1300 nucleotides), were isolated.
- Hu IFN-beta 1 codes for a 20,000 Mr protein, while Hu IFN-beta 2 codes for a 23,000-26,000 Mr protein.
- The two IFN mRNAs do not cross-hybridize; Hu IFN-beta 2 shows partial induction by cycloheximide alone, unlike Hu IFN-beta 1.
Conclusions:
- Human fibroblasts produce at least two distinct mRNA species encoding biologically active interferon.
- These IFN mRNAs exhibit different sizes, coding capacities, and induction profiles, suggesting distinct regulatory mechanisms.
- The findings provide a foundation for understanding the molecular diversity and regulation of human interferon production.