C-Terminal Peptides of Interleukin-6 Modulate the Expression of junB Protooncogene and the Production of Fibrinogen by HepG2 Cells

Abstract

AbstractInterleukin-6 (IL-6) is a 185 amino acid residue helical cytokine with various biological activities (e. g. B cell development, acute phase reaction). We have investigated the role of the 168 185 Cterminal region of IL-6 in the induction of fibrinogen synthesis and expression of junB mRNA using synthetic peptides corresponding to this region. Circular dichroism spectroscopy data suggest that even truncated peptides have a strong tendency to adopt an ordered conformation. Peptides were tested alone or in combination with recombinant hIL-6 on an IL-6 responsive human hepatoma HepG2 cell line. The expression of the protooncogene junB monitored by competitive RTPCR represents an early, while the fibrinogen production detected by sandwich ELISA a late, marker of IL-6 initiated events. We found that peptides depending on their structure modulate spontaneous as well as IL-6 induced fibrinogen production and/or mRNA expression of junB by exhibiting inhibition (in the presence of IL-6) or stimulation (in the absence of IL-6).