Hypoosmolarity influences the activity of transcription factor NF‐κB in rat H4IIE hepatoma cells

Abstract
The influence of anisoosmolarity on NF‐κB binding activity was studied in H4IIE rat hepatoma cells. Hypoosmolarity induced a sustained NF‐κB binding activity whereas the hyperosmotic NF‐κB response was only minor. Hypoosmotic NF‐κB activation was accompanied by degradation of the inhibitory IκB‐α. Protein kinase C, PI3‐kinase, reactive oxygen intermediates and the proteasome apparently participate in mediating the hypoosmotic effect on NF‐κB. Hypoosmolarity plus PMA induced, amplified and prolonged IκB‐α degradation and NF‐κB binding activity. Transforming growth factor β‐induced apoptosis was diminished by hypoosmolarity. However, this anti‐apoptotic effect was probably not related to NF‐κB activation.