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Interferon‐α but not ‐β Genes Require De Novo Protein Synthesis for Efficient Expression in Human Monocytes
Author(s) -
GOBL A. E.,
CEDERBLAD B.,
SANDBERG K.,
ALM G. V.
Publication year - 1992
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1992.tb02848.x
Subject(s) - cycloheximide , messenger rna , peripheral blood mononuclear cell , sendai virus , microbiology and biotechnology , biology , protein biosynthesis , interferon , gene expression , protein synthesis inhibitor , in vitro , gene , immunology , biochemistry
Monocytes produce interferon‐α (IFN‐α) and ‐β when human peripheral blood mononuclear cells (PBMCs) are stimulated in vitro by Sendai virus (SV). We found that about 70% of the IFN‐producing cells (IPCs) expressed both IFN‐α and ‐β mRNA; She rest expressed only IFN‐β mRNA. In the presence of the protein synthesis inhibitor cycloheximide(CHX), the frequency of IFN‐αmRNA containing cells, measured after 6 h, was decreased by 85–90%. Results of nuclear run‐on transcription assays showed that CHX inhibited IFN‐α gene expression. The frequency of IFN‐β mRNA‐containing cells was not reduced by CHX. Actually, a threefold increase was observed at the lower CHX concentrations. Studies on the kinetics of IFN‐α/β mRNA induction showed that CHX accelerated the appearance of IFN‐β mRNA‐containing cells, increased IFN‐β mRNA levels, and delayed the normally occurring post‐inductional decrease of IFN‐β mRNA. Unexpectedly, an initially normal or even accelerated IFN‐α mRNA response was seen in the presence of CHX during the first 3–4 h after SV stimulation. This occurred in a small proportion of the potential IPCs. However, CHX prevented the subsequent marked increase of IFN‐α mRNA levels. Preincubation of PBMCs for 6h in conditioned medium (CM) containing IFN and other cytokines prevented the CHX‐mediated inhibition of IFN‐α mRNA. Without preincubation this was not seen. The preincubation in CM caused an accelerated appearance of IFN‐α mRNA, resembling that of IFN‐β mRNA. The results suggest (that IFN‐α and ‐β genes are differentially regulated in the same monocytes, the former requiring de novo synthesis of intracellular protein(s) for efficient expression.