Double-stranded RNA-dependent protein kinase (PKR) is downregulated by phorbol ester.

The double-stranded RNA-dependent protein kinase (PKR) is one of the key mediators of interferon (IFN) action against certain viruses. PKR also plays an important role in signal transduction and immunomodulation. Understanding the regulation of PKR activity is important for the use of PKR as a tool to discover and develop novel therapeutics for viral infections, cancer and immune dysfunction.

Proteasome-mediated degradation of RNase L in response to phorbol-12-myristate-13-acetate (PMA) treatment of mouse L929 cells.

2'-5' Oligoadenylate (2-5A)-dependent RNase L is one of the key enzymes involved in the molecular mechanisms of interferon (IFN) function. Although the regulation of RNase L by 2-5A has been studied extensively, relatively little is known about how RNase L is controlled by posttranslational processes. Here, we report that phorbol-12-myristate-13-acetate (PMA) treatment of mouse L929 fibroblasts caused rapid degradation of RNase L in a dose-dependent and time-dependent manner.