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.
