[EGF regulation of specific endoribonuclease activity of 26S proteasomes from A431 cells: a potential role of proteasomes in control of mRNA stability].

For the first time it has been shown that RNase activity is induced under the influence of EGF on epidermoid carcinoma cell line A431. Proteasomes from EGF-treated A431 cells destabilize the 3'-untranslated regions of non-muscle beta actin mRNA, creating a specific cleavage pattern. In addition, these particles have been shown to specifically cleave Alu-containing informational RNA. The enzymatic activity under study has been shown to be dependent on phosphorylation of proteasomal subunits and specifically and selectively regulated by Ca and Mg ions. Proteasome involvement in the coordinated control of stability of specific messenger RNA molecules is suggested. The endoribonuclease activity of 26S proteasomes can constitute a link between EGF signaling pathways and RNA stability.