Hybrid Rat Diversity Program inbred rat strain variant analysis
Ontology highlight
ABSTRACT: Analysis of genome variants for HRDP rat strains. Data integration and dissemination through RGD tools. This work is supported by R24 OD024617.
INSTRUMENT(S): -
ORGANISM(S): Rattus Norvegicus
SUBMITTER: Hybrid Rat Diversity Program at the Medical College of Wisconsin
Project description:Background The rat is a major model organism in toxicogenomics and pharmacogenomics, and the use of steady-state hepatic mRNA levels to predict and understand drug toxicity and mechanism is well-established. Surprisingly, the inter- and intra-strain variability of rat mRNA expression has not been evaluated, nor has the extent of its hereditability been established. We address these issues by studying three rat strains (Long-Evans, Hans/Wistar, and Sprague-Dawley) and two F2 lines derived from Long-Evans x Hans/Wistar crosses. Results Using three independent techniques – variance analysis, linear modelling, and unsupervised pattern recognition – we characterize large amounts of both intra- and inter-strain variability in mRNA levels. Importantly, both sources of variability are highly non-random, and are enriched for specific functional groups. Specific transcription-factor binding-sites are enriched in their promoter regions, and these genes occur in “islands” throughout the rat genome. Using the two F2 crosses we study the hereditability of hepatic mRNA levels and show that the majority of rat genes appear to exhibit directional genetics, with only a small fraction having evidence for interacting loci. Finally, a comparison of inter-strain heterogeneity between mouse and rat orthologs shows more heterogeneity in rats than mice, and find that rat and mouse heterogeneity are uncorrelated. Conclusions Our results establish that hepatic mRNA levels are relatively homogeneous within rat strains, but highly variable between them. This variability may be related to increased activity specific transcription-factors, and has clear functional consequences. Future toxicogenomic and pharmacogenomic studies may take advantage of this phenomenon by surveying panels of rat strains. Keywords: Inter-Strain Comparison
Project description:Background Digital gene expression (DGE) profiling has become an established tool to study RNA expression. Here, we provide an in-depth analysis of small RNA DGE profiles from two different rat strains (BN-Lx and SHR) from six different rat tissues (spleen, liver, brain, testis, heart, kidney). We describe the expression patterns of known and novel micro (mi)RNAs and piwi-interacting (pi)RNAs. We confirmed the expression of 589 known miRNAs and identified 56 miRNAs homologous to known human or mouse miRNAs, as well as 45 new rat miRNAs. Furthermore, we confirmed specific A to I editing in brain for mir-376a/b/c and identified mir-377 as a novel editing target. In accordance with earlier findings, we observed a highly tissue-specific expression pattern for all tissues analyzed. The brain was found to express the highest number of tissue-specific miRNAs, followed by testis. Notably, our experiments also revealed robust strain-specific differential miRNA expression in the liver that is caused by genetic variation between the strains. Finally, we identified two types of germline-specific piRNAs in testis, mapping either to transposons or in strand-specific clusters. Taken together, the small RNA compendium described here advances the annotation of small RNAs in the rat genome. Strain and tissue-specific expression patterns furthermore provide a strong basis for studying the role of small RNAs in regulatory networks as well as biological process like physiology and neurobiology that are extensively studied in this model system.
Project description:Spontaneously hypertensive rat (SHR; Rat Genome Database (RGD) ID: 631848) is probably the most commonly used rodent model for essential hypertension. Its minimal congenic subline PD5 ( SHR.PD-(D8Rat42-D8Arb23)/Cub; (RGD ID: 1641851)) which differs by a short segment of chromosome 8 (encompassing only 7 genes) displays lower levels of blood pressure and amelioration of cardiac fibrosis compared to SHR. We used microarray aproach to unravel gene expression differences between SHR and PD5 responsible for the different phenotypes in our rat strains.
Project description:Archive of SNPs without an rsid assignment found through applying reduced representation approaches and imputation. The work is supported by P50 DA037844.
Project description:Audiogenic epilepsy (AE), developing in rodent strains in response to loud sound, is widely used as the model of generalized convulsive epilepsy. The molecular and genetic mechanisms that determine the expression of AE are currently non well understood. In the present work we compared transcriptomes from the inferior and superior colliculi (corpora quadrigemina), the crucial epileptogenic midbrain zone for AE in order to identify genes associated to the AE phenotype. Transcriptomes of rats from three strains were compared: Krushinsky-Molodkina (KM) strain (100% AE-prone); Wistar outbred rats (with no AE proneness) and "0" strain, selected from F2 KMxWistar hybrids for the lack of AE. It is shown that KM strain gene expression profile have a number of characteristic differences from those of Wistar and "0" strains. In particular, KM has increased expression of a number of genes involved in positive regulation of the MAPK signaling cascade, as well as genes, responsible for positive regulation of apoptotic processes. The next characteristic difference between the KM strain from Wistar and "0" is a multiple increase in the expression level of the Ttr gene, which is known to be associated with family amyloid polyneuropathy in humans. Further, the KM strain showed a significant decrease in the expression of the Msh3 gene involved in the DNA mismatch repair system, Acsm5, coding a mitochondrial acyl-CoA synthetase specific for medium chain family member 5, and in a number of genes of the oxidative phosphorylation system, and a number of some other genes. Our data confirm the complex multigenic nature of AE inheritance in rodents. A comparison with the data obtained from other AE rodent strains suggests that the convulsive phenotype could develop differently in audiogenic rat strains selected independently. Although, the finding of parallel differences in certain genes expression in AE-prone hamsters (another rodent species) indicate the common (and crucial) neurogenetic defects, leading to AE phenotype in rodents in general.
Project description:Gene expression profiles in mammary glands of different rat strains are genetically defined. Keywords: Different rat strains and Timecourse
Project description:Background; The rat is a major model organism in toxicogenomics and pharmacogenomics, and the use of steady-state hepatic mRNA levels to predict and understand drug toxicity and mechanism is well-established. Surprisingly, the inter- and intra-strain variability of rat mRNA expression has not been evaluated, nor has the extent of its hereditability been established. We address these issues by studying three rat strains (Long-Evans, Hans/Wistar, and Sprague-Dawley) and two F2 lines derived from Long-Evans x Hans/Wistar crosses. Results; Using three independent techniques â variance analysis, linear modelling, and unsupervised pattern recognition â we characterize large amounts of both intra- and inter-strain variability in mRNA levels. Importantly, both sources of variability are highly non-random, and are enriched for specific functional groups. Specific transcription-factor binding-sites are enriched in their promoter regions, and these genes occur in âislandsâ throughout the rat genome. Using the two F2 crosses we study the hereditability of hepatic mRNA levels and show that the majority of rat genes appear to exhibit directional genetics, with only a small fraction having evidence for interacting loci. Finally, a comparison of inter-strain heterogeneity between mouse and rat orthologs shows more heterogeneity in rats than mice, and find that rat and mouse heterogeneity are uncorrelated. Conclusions; Our results establish that hepatic mRNA levels are relatively homogeneous within rat strains, but highly variable between them. This variability may be related to increased activity specific transcription-factors, and has clear functional consequences. Future toxicogenomic and pharmacogenomic studies may take advantage of this phenomenon by surveying panels of rat strains. Experiment Overall Design: We profiled the basal mRNA levels in three strains and two lines of rat, each using four biological replicates.