Genetic determinants of Metabolic Syndrome in Lyon Hypertensive rats

[摘要] Metabolic Syndrome (MetS) is a collective term for a cluster of disorders, including dysglycemia, central obesity, dyslipidemia, hypertension, and eventual end organ damage. The combination of these disorders increases the risk of many kinds of end organ damages, including coronary heart disease, kidney failure, and cirrhosis. MetS is highly prevalent in the United States, affecting one third of the U.S. population in a 2009 estimate. The Lyon strains are three rat strains selectively inbred from the same colony of outbred rats for different blood pressure levels. The Lyon Hypertensive (LH) strain, in addition to its essential hypertension phenotype, also harbors many disorders found in MetS. The Lyon Normotensive (LN) rat strain is completely devoid of these symptoms, while Lyon Low-pressure (LL) is obese but is resistant to other traits of MetS. Rat chromosome 17 (RNO17) has previously been linked with many of MetS' phenotypes in Lyon Hypertensive (LH). In this project, we are using a mixture of genetical genomics and systems biology methods to identify genetic elements that may cause the LH phenotype. Divergent haplotype blocks between the Lyon strains were first identified by the analysis of the distribution of observed strain differences (OSD) calculated from the result of genome resequencing. Divergent haplotype regions totaling less than 16% of the rat genome that contain more than 95% of the identified SNPs in each of the three pairwise comparisons between the Lyon strains have been identified; in particular, there are 14 divergent haplotype blocks between LH and LN spanning 7.7% of RNO17 that harbor more than 97% of SNPs identified on RNO17. Twenty-five genes in these regions were thus identified as potential genetic determinants for MetS. Phenotypic QTLs (pQTL) and expression QTLs (eQTL) mapping from a cohort of male LH × LN F2 rats were performed by putting the cohort on a 15-week phenotyping protocol and genome-wide genotyping. Total liver RNA from 36 individuals from the cohort were sequenced to provide expression data for eQTL mapping. We have mapped 22 pQTLs that are statistically linked to 15 traits, with RNO17 linked to 15 traits associated with blood pressure, leptin and body weight. We have also identified 1,200 eQTLs from this cohort, including 11 eQTLs with cis-linkage with one or more genes. On RNO17, we have identified two SNPs between 29-39 Mb which are significantly linked to the expression of 85 genes; the only gene with cis-linkage with these SNPs, RGD1562963, was

[发布机构] University of Iowa