Cloning a Novel Metallophosphoesterase Gene from a Kidney Cdna Library of Hypertensive Rat

Background and purpose: Genetic and environmental factors may contribute to the pathogenesis of essential hypertension . To facilitate genetic studies of hypertension and renal disorders, we sought to clone novel genes from a modified, equalized kidney (MEK) cDNA library of a spontaneously hypertensive rat (SHR). Methods: A kidney cDNA library of an SHR was synthesized using the modified equalization method. Inserts of 350 random clones were amplified by polymerase chain reaction (PCR) and sequenced, of which 246 were presumably unknown after being compared against a nonredundant database in the GenBank. The cDNA ends of clone 383 were obtained by rapid amplification of cDNA ends, sequenced, and then analyzed with Translate, Prosite, Profile, SignalP, and TMpred programs. Results: The full- length cDNA was 938 bp, and translated into a 182-amino acid protein. The deduced protein had a metallophosphoesterase domain, a signal peptide at its amino end, a protein kinase C phosphorylation site, and a transmembrane domain. Northern blot analysis revealed that this gene was expressed in the heart, brain, spleen, lungs, liver, skeletal muscles , kidneys and testes of Sprague-Dawley rats. A putative protein of Arabidopsis thaliana shares 62% homology with protein 38S, but the two proteins differ in terms of function and structure. Conclusions: Our results support that protein 38S is a novel membrane metallophosphoesterase, although its function in the kidneys remains to be elucidated. This study also demonstrates the feasibility of using PCR to clone novel genes from our MEK cDNA library