Abstract
Background: Three congenic rat strains (SB2a, SB2b and SB2e) were created by chromosome (Chr) 2 fragment introgression from normotensive Brown Norway (BN) rats into hypertensive Dahl salt sensitive (SS) background. SB2a and SB2b rats fed a normal-salt diet presented reduced blood pressure (BP) and inflammation when compared to SS rats. We hypothesized that BN-Chr2 contains antihypertensive and anti-inflammatory genes that could prevent high-salt diet (HSD)-induced BP elevation and vascular injury in SB2a and SB2b rats. These genes will be identified using microRNA (miRNA) and total RNA expression profiling analysis in aorta of congenic rats fed a HSD. Methods and Results: Four-to-6 week-old male SS, SS, SB2a and SB2b rats were fed a HSD (4% NaCl) for 8 weeks or until they developed a stroke as manifested by seizures. Systolic blood pressure (SBP) was measured by telemetry. Systolic BP was higher in SB2b but not SB2a when compared to SS (185±8, 167±7 vs 168±5 mm Hg). Total RNA was extracted from aorta and used to construct libraries for small and total RNA sequencing using Illumina HiSeq-2500. The bioinformatics pipeline included: FastQC for quality control, STAR for genome (Rattus norvegicus, release-86) alignment, mirdeep2 for miRNA annotation and counting, Htseq-count for mRNA and long non-coding RNA annotation and counting; R for differential expression analysis. Differentially expressed miRNAs and genes (mRNAs and non-coding RNAs) were identified in SB2a vs SS (miRNAs: 11 up and 10 down; genes: 92 up and 91 down) and in SB2b vs SS (miRNAs: 3 up and 2 down; genes: 10 up and 13 down) with FDR<0.05. Differentially expressed genes encoded within different BN-Chr2 congenic portions were identified in SB2a vs SS (genes: 7 up and 2 down) and SB2b vs SS (genes: 6 up and 4 down). Conclusions and Perspectives: Differentially expressed BN-Chr2 encoded genes were identified in aorta of congenic SB2a and SB2b rats fed HSD. Whether these genes play a role in HSD-induced BP elevation and vascular inflammation remains to be determined.
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