Cardiac transcriptome profiles of S.LEW congenic strain compared with the hypertensive Dahl S rat

Despite inheritance of hypertension in families, identifying genetic mechanisms predisposing individuals to hypertension has remained challenging. The effects of single genes contributing to the development of hypertension may not be readily detected in individuals whose genomes also contain other genetic factors that resist hypertension. By using a highly permissive rat genome for inherited hypertension, we demonstrate that increased expression of one such gene, Rififylin (Rffl), is a novel inherited risk factor for hypertension and increased mortality. Animals overexpressing Rffl demonstrated delayed endocytic recycling, accumulated polyubiquitinated proteins, increased beats/min of neonatal cardiomyocytes, had shorter QT-intervals and developed salt-insensitive hypertension very early in their life (50-52 days). Thus, the discovery of a physiological link between overexpression of rififylin and the development of hypertension constitutes a novel mechanism that could be targeted for rectifying normal QT-interval and preventing hypertension. Six male S control and 6 male congenic S.LEW(10)x12x2x3x5 rats born on the same day were selected, weaned at 30 days of age, and caged with 1 congenic and 1 S rat per cage. They were raised on a low-salt (0.3%) diet (Harlan Teklad diet TD 7034; Harlan–Sprague-Dawley) and sacrificed at 53 days of age and total RNAs were isolated from the heart. The isolated RNA from two animals were pooled together and considered as one biological sample. Three such RNA samples from S and congenic rats were used for the cRNA preparation. cRNA was prepared and fragmented as suggested by Affymetrix technical manual, and simultaneously hybridized (15 µg adjusted cRNA for each chip) to Rat Expression Array 230 2.0 (3' IVT Expression Analysis). Statistical analyses of the microarray data were performed with BH adjustment using R statistical package (version 2.8.1).