Expression pattern in a modified equalized kidney cDNA library of hypertensive rat

Background: Genes with important functions and rarely expressed would proba bly more easily be cloned from a modified equalized kidney cDNA library for further investigation. Methods: A kidney cDNA library of a spontaneously h ypertensive rat was synthesized by a modified equalization method. Inserts of random clones were amplified by PCR and sequenced. Sequences were compar ed against a nonredundant database in GenBank. The cDNA profile was compare d with an expression profile of a mouse renal proximal tubule cDNA library. Seven clones were analyzed by Northern blot analysis. The cDNA ends of two novel genes were amplified by PCR, sequenced and analyzed. Results: 336 cD NA clones were analyzed and grouped into 323 species of transcript with 77 species similar to previously reported genes. Northern blot analysis identi fied one kidney-specific, one rarely expressed and lung-specific, and anoth er relatively testis-specific gene. Two novel genes were cloned. One was 4. 1 kb in length and encoded a 390-amino acid zinc-finger protein. Another wa s 2.5 kb and encoded a 474-amino acid protein of unknown function. Compared with the expression profile of a mouse renal proximal tubule cDNA library, this kidney library had a lower proportion of ribosomal genes and had a gr eater proportion of genes for signal transduction and DNA or RNA binding. C onclusions: Rare or novel genes could be more easily isolated from this lib rary for molecular study of hypertension and renal pathophysiology, Copyright (C) 2000 S. Karger AG, Basel.