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Identification of genes influencing skeletal phenotypes in congenic P/NP rats.

ABSTRACT: We previously showed that alcohol-preferring (P) rats have higher bone density than alcohol-nonpreferring (NP) rats. Genetic mapping in P and NP rats identified a major quantitative trait locus (QTL) between 4q22 and 4q34 for alcohol preference. At the same location, several QTLs linked to bone density and structure were detected in Fischer 344 (F344) and Lewis (LEW) rats, suggesting that bone mass and strength genes might cosegregate with genes that regulate alcohol preference. The aim of this study was to identify the genes segregating for skeletal phenotypes in congenic P and NP rats. Transfer of the NP chromosome 4 QTL into the P background (P.NP) significantly decreased areal bone mineral density (aBMD) and volumetric bone mineral density (vBMD) at several skeletal sites, whereas transfer of the P chromosome 4 QTL into the NP background (NP.P) significantly increased bone mineral content (BMC) and aBMD in the same skeletal sites. Microarray analysis from the femurs using Affymetrix Rat Genome arrays revealed 53 genes that were differentially expressed among the rat strains with a false discovery rate (FDR) of less than 10%. Nine candidate genes were found to be strongly correlated (r(2) > 0.50) with bone mass at multiple skeletal sites. The top three candidate genes, neuropeptide Y (Npy), alpha synuclein (Snca), and sepiapterin reductase (Spr), were confirmed using real-time quantitative PCR (qPCR). Ingenuity pathway analysis revealed relationships among the candidate genes related to bone metabolism involving beta-estradiol, interferon-gamma, and a voltage-gated calcium channel. We identified several candidate genes, including some novel genes on chromosome 4 segregating for skeletal phenotypes in reciprocal congenic P and NP rats.

SUBMITTER: Alam I

PROVIDER: S-EPMC3153136 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Identification of genes influencing skeletal phenotypes in congenic P/NP rats.

Alam Imranul I Carr Lucinda G LG Liang Tiebing T Liu Yunlong Y Edenberg Howard J HJ Econs Michael J MJ Turner Charles H CH

Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research 20100601 6

We previously showed that alcohol-preferring (P) rats have higher bone density than alcohol-nonpreferring (NP) rats. Genetic mapping in P and NP rats identified a major quantitative trait locus (QTL) between 4q22 and 4q34 for alcohol preference. At the same location, several QTLs linked to bone density and structure were detected in Fischer 344 (F344) and Lewis (LEW) rats, suggesting that bone mass and strength genes might cosegregate with genes that regulate alcohol preference. The aim of this ...[more]

PMID: 20200994

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Project description:Bone mineral density and structure candidate gene analysis in alcohol-non-preferring (NP), alcohol-preferring (P), congenic NP (NP.P) and congenic P (P.NP) rats Genetic mapping in alcohol-preferring (P) and alcohol-non-preferring (NP) rats has identified a major quantitative trait locus (QTL) in the region between q22 – q34 on chromosome (Chr) 4 for alcohol preference. In a separate genome-wide linkage study, using inbred Fischer 344 (F344) and Lewis (LEW) rats, several QTL linked to bone density and structure were identified at the same location suggesting that bone mass and strength genes might co-segregate with genes that regulate the alcohol preference trait. The aim of this study is to identify the genes segregating for skeletal phenotypes and alcohol trait in congenic P/NP rats. We compared bone mineral content (BMC), areal/volumetric bone mineral density (aBMD/vBMD) and biomechanical strength at different skeletal sites from 6-month-old inbred and congenic P/NP rats. Transfer of the NP Chr 4 QTL into P background significantly increased body weight but decreased BMC, aBMD/vBMD in whole body, cranium, femur, and lumbar vertebrae. On the other hand, transfer of P Chr 4 QTL into NP background significantly decreased body weight but increased BMC and aBMD in the same skeletal sites. Microarray analysis was performed from the femurs of 4-week-old rats (n = 5 per strain) using Affymetrix Rat Genome 230 2.0 arrays. A total of 53 genes, including 41 candidate genes and 12 predicted genes, were differentially expressed among all strains of rats with a false discovery rate (FDR) less than 10%. Several candidate genes from microarray analysis were found to be were strongly correlated (r2>0.50) with different skeletal phenotypes. Gene expression of top 3 candidate genes from microarray profiling was validated by quantitative real-time PCR (qRT-PCR). Ingenuity pathway analysis revealed relationships among the candidate genes related to bone metabolism including pathways related to beta-estradiol, tumor necrosis factor and androgen receptor. Keywords: Comparison of gene expression profiles between NP, P, NP.P and P.NP rats

Project description:Bone mineral density and structure candidate gene analysis in alcohol-non-preferring (NP), alcohol-preferring (P), congenic NP (NP.P) and congenic P (P.NP) rats; Genetic mapping in alcohol-preferring (P) and alcohol-non-preferring (NP) rats has identified a major quantitative trait locus (QTL) in the region between q22 â?? q34 on chromosome (Chr) 4 for alcohol preference. In a separate genome-wide linkage study, using inbred Fischer 344 (F344) and Lewis (LEW) rats, several QTL linked to bone density and structure were identified at the same location suggesting that bone mass and strength genes might co-segregate with genes that regulate the alcohol preference trait. The aim of this study is to identify the genes segregating for skeletal phenotypes and alcohol trait in congenic P/NP rats. We compared bone mineral content (BMC), areal/volumetric bone mineral density (aBMD/vBMD) and biomechanical strength at different skeletal sites from 6-month-old inbred and congenic P/NP rats. Transfer of the NP Chr 4 QTL into P background significantly increased body weight but decreased BMC, aBMD/vBMD in whole body, cranium, femur, and lumbar vertebrae. On the other hand, transfer of P Chr 4 QTL into NP background significantly decreased body weight but increased BMC and aBMD in the same skeletal sites. Microarray analysis was performed from the femurs of 4-week-old rats (n = 5 per strain) using Affymetrix Rat Genome 230 2.0 arrays. A total of 53 genes, including 41 candidate genes and 12 predicted genes, were differentially expressed among all strains of rats with a false discovery rate (FDR) less than 10%. Several candidate genes from microarray analysis were found to be were strongly correlated (r2>0.50) with different skeletal phenotypes. Gene expression of top 3 candidate genes from microarray profiling was validated by quantitative real-time PCR (qRT-PCR). Ingenuity pathway analysis revealed relationships among the candidate genes related to bone metabolism including pathways related to beta-estradiol, tumor necrosis factor and androgen receptor. Experiment Overall Design: Comparison of differentially expressed genes between 4q22-4q34 on chromosome 4 in NP, P, NP.P and P.NP rats.

Project description:BackgroundA highly significant quantitative trait locus (QTL) on chromosome 4 that influenced alcohol preference was identified by analyzing crosses between the iP and iNP rats. Congenic strains in which the iP chromosome 4 QTL interval was transferred to the iNP (NP.P) exhibited the expected increase in alcohol consumption compared with the iNP background strain. This study was undertaken to identify genes in the chromosome 4 QTL interval that might contribute to the differences in alcohol consumption between the alcohol-naïve congenic and background strains.MethodsRNA from 5 brain regions from each of 6 NP.P and 6 iNP rats was labeled and analyzed separately on an Affymetrix Rat Genome 230 2.0 microarray to look for both cis-regulated and trans-regulated genes. Expression levels were normalized using robust multi-chip average (RMA). Differential gene expression was validated using quantitative real-time polymerase chain reaction. Five individual brain regions (nucleus accumbens, frontal cortex, amygdala, hippocampus, and striatum) were analyzed to detect differential expression of genes within the introgressed QTL interval, as well as genes outside that region. To increase the power to detect differentially expressed genes, combined analyses (averaging data from the 5 discrete brain regions of each animal) were also carried out.ResultsAnalyses within individual brain regions that focused on genes within the QTL interval detected differential expression in all 5 brain regions; a total of 35 genes were detected in at least 1 region, ranging from 6 genes in the nucleus accumbens to 22 in the frontal cortex. Analysis of the whole genome detected very few differentially expressed genes outside the QTL. Combined analysis across brain regions was more powerful. Analysis focused on the genes within the QTL interval confirmed 19 of the genes detected in individual regions and detected 15 additional genes. Whole genome analysis detected 1 differentially expressed gene outside the interval.ConclusionsCis-regulated candidate genes for alcohol consumption were identified using microarray profiling of gene expression differences in congenic animals carrying a QTL for alcohol preference.

Project description:The goal of this study was to identify candidate genes that may influence alcohol consumption by comparing gene expression in 5 brain regions of alcohol-naïve iP and P.NP rats. Background: Selectively bred P (alcohol preferring) and NP (alcohol non-preferring) rats differ greatly in alcohol preference, in part due to a highly significant QTL on chromosome 4. Reciprocal congenic strains in which the iP chromosome 4 QTL interval was transferred to the iNP background (NP.P) and the iNP chromosome 4 QTL was transferred to the iP background (P.NP) exhibited alcohol consumption scores that correlated with the introgressed interval. The goal of this study was to identify candidate genes that may influence alcohol consumption by comparing gene expression in 5 brain regions of alcohol-naïve iP and P.NP rats. Methods: RNA from the amygdala, nucleus accumbens, hippocampus, caudate putamen, and frontal cortex from each of 8 iP and 8 P.NP rats was labeled and analyzed on Affymetrix Rat Genome 230 2.0 microarrays. Expression levels were normalized using robust multi-chip average (RMA), and differential gene expression was measured in individual brain regions and in the average of the five brain regions. Differential gene expression was validated using quantitative real-time PCR. Meta-analysis was applied to compare microarray data from this experiment with data from the reciprocal congenic strains NP.P vs. iNP (Carr et al, 2007). Results: We detected between 72 (nucleus accumbens) and 89 (hippocampus) cis-regulated probe sets within the QTL that significantly differed between the strains in the five brain regions. There was significant overlap among the regions; 157 cis-regulated probe sets were detected in at least one brain region, of which 104 showed differential expression in more than one region. Fewer trans-regulated probe sets were detected, ranging from 7 in the amygdala to 54 in the caudate putamen, and most of these differed in only one region; only 10 of the 85 trans-regulated probe sets differed in more than one region. To increase the power to detect differentially expressed genes, data from the five discrete brain regions of each animal were averaged; in this analysis we detected 141 cis-regulated probe sets and 207 trans-regulated probe sets. Meta-analysis comparing the present results from iP vs. P.NP rats with an earlier experiment that used the reciprocal congenic NP.P vs. iP demonstrated that 74 cis-regulated probe sets were differentially expressed in the same direction and with a consistent magnitude of difference in both experiments. No consistent trans-regulated probe sets were identified. Conclusions: Cis-regulated candidate genes for alcohol consumption that lie within the chromosome 4 QTL were identified and confirmed by meta-analysis with the reciprocal congenic NP.P vs iNP study. These genes are strong candidates for producing the difference in alcohol preference and consumption between the iP and iNP rats. There was little evidence for consistent trans-acting effects. Keywords: comparison of gene expression profiles for strain1 (P rat) vs. strain2 (P.NP rat)

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Identification of genes influencing skeletal phenotypes in congenic P/NP rats.

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Identification of genes influencing skeletal phenotypes in congenic P/NP rats.

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