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Genetic variation in radiation-induced expression phenotypes.

ABSTRACT: Studies have demonstrated that natural variation in the expression level of genes at baseline is extensive, and the determinants of this variation can be mapped by a genetic-linkage approach. In this study, we used lymphoblastoid cells to explore the variation in radiation-induced transcriptional changes. We found that, among normal individuals, there is extensive variation in transcriptional response to radiation exposure. By studying monozygotic twins, we demonstrated that there is evidence of a heritable component to this variation. The postradiation variation in the expression level of several genes, including the ferredoxin reductase gene (FDXR) and the cyclin-dependent kinase inhibitor 1A gene (CDKN1A), is significantly greater (P<.001) among twin pairs than within twin pairs. The induction of FDXR by radiation showed a bimodal distribution. Our findings have important implications for understanding the genetic basis of radiation response, which has remained largely unknown due to the lack of family material needed for genetic studies. Our approach, which uses expression phenotypes in cell lines, allows us to expose cells from family members to radiation. Similar study design can be applied to dissect the genetic basis of other complex human traits.

SUBMITTER: Correa CR

PROVIDER: S-EPMC1182118 | biostudies-literature | 2004 Nov

REPOSITORIES: biostudies-literature

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Genetic variation in radiation-induced expression phenotypes.

Correa Candace R CR Cheung Vivian G VG

American journal of human genetics 20040909 5

Studies have demonstrated that natural variation in the expression level of genes at baseline is extensive, and the determinants of this variation can be mapped by a genetic-linkage approach. In this study, we used lymphoblastoid cells to explore the variation in radiation-induced transcriptional changes. We found that, among normal individuals, there is extensive variation in transcriptional response to radiation exposure. By studying monozygotic twins, we demonstrated that there is evidence of ...[more]

PMID: 15359380

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Project description:Iron overload causes inhibition of hepatic uroporphyrinogen decarboxylase (UROD) and uroporphyria in C57BL/10ScSn but not DBA/2 mice [Smith, Cabral, Carthew, Francis and Manson (1989) Int. J. Cancer 43, 492-496]. We have investigated the induction of uroporphyria in 12 inbred strains of mice 25 weeks after iron treatment (600 mg/kg) to determine if there was any correlation with the Ah locus. Under these conditions, inhibition of UROD occurred to varying degrees in Ahd mice (SWR and AKR) as well as nominally Ahb-1 (C57BL/6J, C57BL/10ScSn and C57BL/10-cc) and Ahb-2 strains (BALB/c and C3H/HeJ). Five other Ahb or Ahd strains (C57BL/Ks, A/J, CBA/J, LP and DBA/2) were unaffected. Thus there appeared to be no correlation with the Ah phenotype and this illustrated that some other variable inherited factors are involved. Comparisons between another susceptible strain, A2G, and the congenic A2G-hr/+strain (carrying the recessive hr gene) showed a modulating influence associated with the hr locus. In contrast with individual mice of inbred strains, which showed consistent responses to iron, those of the outbred MF1 strain showed a spectrum of sensitivities as might be expected for a heterogeneic stock. The rate of porphyria development was accelerated by administration of 5-aminolaevulinic acid (5-ALA) in the drinking water, but this did not overcome strain differences. Among four strains the order of susceptibility was SWR > C57BL/10ScSn > C57B1/6J > DBA/2 (the last strain was completely resistant). With degrees of iron loading greater than 600 mg of Fe/kg (1200-1800 mg of Fe/kg) C57BL/10ScSn mice (after 20 weeks) and SWR mice (after 5 weeks which included 4 weeks of 5-ALA treatment) had less inhibition of UROD and a lower uroporphyric response, showing that there was an optimum level of liver iron concentration. Studies on selected microsomal enzyme activities associated with cytochrome P-450 showed no correlation with the propensities of strains to develop porphyria. These activities included the NADPH-dependent oxidation of uroporphyrinogen I to uroporphyrin I.

Dataset Information

Genetic variation in radiation-induced expression phenotypes.

Publications

Genetic variation in radiation-induced expression phenotypes.

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