Mutations alter transcription factor binding to the renin gene first intron of the spontaneously hypertensive rat.

Overexpression of the renin gene has been found in the spontaneously hypertensive rat (SHR) of the Okamoto strain. We have demonstrated mutations within the renin gene first intron unique to SHR. In the present study we examined whether these mutations disrupt transcriptional factor binding to this region. Synthetic double-strand oligonucleotides were used in gel mobility shift assays. The sequences spanned +490 - +514 and +925 - +944 in the rat renin gene intron 1. These regions contain consensus sequences for transcriptional factors IF3 and E2A. The probes were radiolabelled at the 5′-end with 32P. Nuclear extracts were prepared from kidney, liver, adrenal gland, heart, brainstem, lung and spleen of Sprague-Dawley (SD) rats. Resultant DNA-protein complexes were analyzed by gel electrophoresis followed by autoradiography. The intensity of DNA-protein bands were semi-quantified by densitometry. Specific nuclear proteins were identified which bound to IF3 and E2A motifs and displayed different tissue-specific patterns. The affinities of nuclear protein binding to IF3 and E2A elements from SHR renin gene first intron were about 60 and 20 times higher respectively than that from Wistar Kyoto and SD rats. We conclude that the mutations in the renin first intron of SHR interrupt transcriptional factor binding to this gene and may be the molecular basis for its overexpression.