RAT LUNG CONTAINS A DEVELOPMENTALLY-REGULATED MANGANESE SUPEROXIDE-DISMUTASE MESSENGER RNA-BINDING PROTEIN

It has become increasingly clear that RNA-binding proteins play an imp ortant role in the regulation of gene expression. The presence in rat lung of a specific, redox-sensitive catalase RNA-binding protein was r ecently reported (Clerch, L. B., and D. Massaro, 1992. J. Biol. Chem. 267:2853). In order to determine if specific manganese superoxide dism utase (MnSOD) RNA-binding proteins exist, we tested whether protein in rat lung extract would bind to P-32-labeled MnSOD RNA. Using a gel mo bility shift assay we show rat lung protein forms specific complexes w ith a 216 b fragment of the 3' untranslated region of MnSOD RNA and th e binding requires the presence of free sulfhydryl groups. Competition studies indicate MnSOD RNA-binding protein is different from catalase RNA-binding protein. Furthermore, unlike catalase RNA-binding protein , rat lung MnSOD RNA-binding protein activity is developmentally regul ated; there is less MnSOD RNA-protein binding activity in adult rat lu ng extract compared to prenatal or neonatal rat lung extracts. We conc lude the lung contains developmentally regulated MnSOD mRNA-binding pr otein that is redox sensitive.