Objective: To search and clone novel genes related to hypertension.
Methods: Using differential display, a RNA mapping method, we identified differentially expressed RNAs from cultured VSMCs of WKY and SHR. Down-expressed cDNAs of WKY were cloned.
Results: A novel cDNA (rHRG-1) obtained contained 4,160 bp nucleotides and an open reading frame which encoded 551 amino acid residues. Its molecular weight was 62,644. Northern blot analysis showed that the mRNA was expressed not only in VSMCs but in various rat tissues (heart, liver, brain, lung and kidney). Besides, the expression of rHRG-1 mRNA in various tissues (heart, liver, brain and kidney) of WKY rat was higher than that in those tissues of SHR. Semi-quantitative RT-PCR analysis showed that the expression of rHRG-1 mRNA was down-regulated by treating cells with angiotensin-II, endothelin-I or interleukin-I. VSMCs proliferation and hypertension-stimulating factor, but was up-regulated when treating cells with ANF, CGRP or adrenomedullin which could inhibit the proliferation of VSMCs and attenuate hypertension. These effects could be blocked or attenuated by corresponding antagonists or antibodies.
Conclusion: The isolated novel rat cDNA (rHRG-1) is related to VSMCs proliferation or hypertension. It may antagonize the proliferation of VSMCs and may be involved in the formation of hypertension.