Differential response of the murine IL-12 p35 gene to lipopolysaccharide compared with interferon-gamma and CD40 ligation.
Expression of the heterodimeric cytokine interleukin-(IL-)12 is induced by pattern recognition receptors responding to microbial stimuli such as lipopolysaccharide (LPS) and products of the immune system such as interferon-gamma (IFN-gamma) and CD40L. The formation of bioactive IL-12 requires equimolar synthesis of p35 and p40 subunits. However, p35 expression limits the amount of IL-12 formed. Transcription of the gene for the p35 subunit of IL-12 initiates within the first exon, an alternate first exon (exon 1a), or second exon. Here we show that LPS and IFN-gamma/CD40 ligation increase the amount of total p35 mRNA in splenic adherent cells (SAC) to a similar extent. However, the exon 1 transcript was a smaller fraction of total p35 mRNA in IFN-gamma/CD40-stimulated cells than in unstimulated or LPS-stimulated cells. Despite comparable levels of total p35 mRNA, LPS-induced p35 exon 1 transcripts led to significantly more bioactive IL-12 from SAC than IFN-gamma/CD40-induced exon 1a/exon 2 transcripts as measured by ELISA. The data suggest that LPS-inducible p35 synthesis from exon 1 p35 transcripts leads to greater amount of bioactive IL-12 than IFN-gamma/CD40-induced p35 expression from alternate p35 exon 1a/exon 2 transcripts.
Vaidyanathan
H
H
Center for Biological Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68583-0740, USA.
Gentry
J D
JD
Weatherman
A
A
Schwartzbach
S D
SD
Petro
T M
TM
D000818:Animals; D023201:CD40 Ligand / Q000235:genetics / Q000494:pharmacology*; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D005091:Exons; D005260:Female; D007371:Interferon-gamma / Q000235:genetics / Q000494:pharmacology*; D018664:Interleukin-12 / Q000096:biosynthesis / Q000235:genetics*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000187:drug effects* / Q000378:metabolism; D014158:Transcription, Genetic
D017931:DNA Primers; D004268:DNA-Binding Proteins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D023201:CD40 Ligand; D018664:Interleukin-12; D007371:Interferon-gamma