Ciliary neurotrophic factor regulates fibrinogen gene expression in hepatocytes by binding to the interleukin-6 receptor.

Treatment of primary rat hepatocytes with ciliary neurotrophic factor (CNTF) resulted in increased fibrinogen mRNA levels and protein expression in a time- and dose- dependent manner. The stimulation was similar to but not as potent as the response observed with interleukin-6 (IL-6). Equilibrium binding studies using radioiodinated CNTF revealed approximately 1,900 binding sites per cell with a binding affinity of 1.6-2.0 nM, indicating the presence of specific CNTF receptors on the hepatocyte surface. Binding of CNTF to the hepatocyte surface could be competed by IL-6. Additionally, IL-6 binding was also competed by CNTF, although not entirely. These findings suggest that the CNTF-induced stimulation of fibrinogen gene expression occurs, at least in part, by this cytokine's interaction with the IL-6 receptor.