Stabilization and correct localization of mRNA are important features of renin synthesis. To elucidate the molecular basis of posttranscriptional control of renin synthesis, we analysed the interaction of human prepro-renin (hREN) mRNA 3‚-untranslated region (3‚UTR) with proteins of renin synthesizing Calu-6 cells.

To identify hREN mRNA binding proteins, electromobility shift assays, UV cross-linking and RNA-affinity chromatography with subsequent MALDI-TOF-MS were performed. A sequence alignment revealed CU-rich clusters in the 3‚-UTR of hREN mRNA. These are highly conserved across species. Moreover, the sequences resemble the 3‚-UTR control element LOX-DICE (found in lipoxygenase mRNA and other mRNAs) and the α-stability complex binding site of globin mRNAs. Six proteins were unambigously identified as hREN mRNA 3‚-UTR binding proteins: hnRNP E1 (synonyms α-CP or PCBP), hnRNP K, dynamin, nucleolin, YB-1 and MINT-homologous protein. These proteins contain various RNA-binding motifs, and most have been described in the context of mRNA binding and mRNA stabilization. Four proteins, for which antibodies were available, were verified by immunological methods (dynamin, nucleolin, hnRNP E1, YB-1). All immunologically detectable hREN mRNA binding proteins were found not only in free form in the cytoplasm, but also in hREN mRNA containing mRNP complexes (polysomes and postpolysomal free mRNP particles). Four of the six proteins (hnRNPs E1 and K, nucleolin and YB-1) have been identified in other mRNP complexes alone or in combination as crucial components of posttranscriptional control of gene expression, in particular in mRNA stabilization.

This work was supported by the German Research Foundation.