Interferon‐γ Stimulation of Messenger RNA for Human Secretory Component (poly‐Ig Receptor) Depends on Continuous Intermediate Protein Synthesis

Publisher Website
Google Scholar
Abstract
Secretory component (SC or poly‐Ig receptor) plays a key role in mucosal external body fluids. The aim of this study was to elucidate the molecular events underlying IFN‐γ‐dependent up‐regulation of SC. Using a human SC cDNA clone isolated by our laboratory, we found that IFN‐γ up‐regulated SC mRNA levels in a time‐ and concentration‐dependent manner. Moreover, in situ hybridization showed a striking increase of SC mRNA‐positive HT‐29 cells after IFN‐γ treatment. Inhibition with 5,6‐dichloro‐l‐β‐ribofuranosyl‐benzimidazole (DRB) indicated a half‐life for IFN‐γ‐induced SC mRNA of approximately 1 h. Cycloheximide (CHX) abolished the IFN‐γ‐induced accumulation of SC mRNA in a reversible manner; the time‐course suggested that de novo synthesis of protein factor(s) with a turnover time shorter than 6 h was required for accumulation of SC message. IFN‐γ‐stimulated up‐regulation of SC expression therefore appears to depend on molecular events similar to those taking place for the activation of several other genes in the Ig supergene family.