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Genomic imprinting and genetic effects on muscle traits in mice.

Kärst S, Vahdati AR, Brockmann GA, Hager R - BMC Genomics (2012)

Bottom Line: Imprinting is increasingly recognized as an important source of variation in complex traits, however, its role in explaining variation in muscle and physiological traits, especially those of commercial value, is largely unknown compared with genetic effects.Surprisingly, variation in glycogen content and potential was only modulated by imprinting effects.Further, in contrast to general assumptions, our results show that genomic imprinting can impact physiological traits measured at adult stages and that the expression does not have to follow the patterns of paternal or maternal expression commonly ascribed to imprinting effects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Crop and Animal Sciences, Humboldt-University Berlin, Berlin, Germany.

ABSTRACT

Background: Genomic imprinting refers to parent-of-origin dependent gene expression caused by differential DNA methylation of the paternally and maternally derived alleles. Imprinting is increasingly recognized as an important source of variation in complex traits, however, its role in explaining variation in muscle and physiological traits, especially those of commercial value, is largely unknown compared with genetic effects.

Results: We investigated both genetic and genomic imprinting effects on key muscle traits in mice from the Berlin Muscle Mouse population, a key model system to study muscle traits. Using a genome scan, we first identified loci with either imprinting or genetic effects on phenotypic variation. Next, we established the proportion of phenotypic variation explained by additive, dominance and imprinted QTL and characterized the patterns of effects. In total, we identified nine QTL, two of which show large imprinting effects on glycogen content and potential, and body weight. Surprisingly, all imprinting patterns were of the bipolar type, in which the two heterozygotes are different from each other but the homozygotes are not. Most QTL had pleiotropic effects and explained up to 40% of phenotypic variance, with individual imprinted loci accounting for 4-5% of variation alone.

Conclusion: Surprisingly, variation in glycogen content and potential was only modulated by imprinting effects. Further, in contrast to general assumptions, our results show that genomic imprinting can impact physiological traits measured at adult stages and that the expression does not have to follow the patterns of paternal or maternal expression commonly ascribed to imprinting effects.

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Imprinting patterns for A) body weight on Mc12.1,B) glycolytic content and C) glycolytic potential on the pleiotropic QTL Mc19.1. The pattern of imprinting effect is bipolar expression for all the traits. We have used uncorrected trait means (i.e. before adjustment for direction of cross and sex) to illustrate the magnitude of effects in this figure.
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Figure 1: Imprinting patterns for A) body weight on Mc12.1,B) glycolytic content and C) glycolytic potential on the pleiotropic QTL Mc19.1. The pattern of imprinting effect is bipolar expression for all the traits. We have used uncorrected trait means (i.e. before adjustment for direction of cross and sex) to illustrate the magnitude of effects in this figure.

Mentions: We discovered genomic imprinting effects located on chromosome 19 with a strong effect on glycolytic potential and content. The imprinting pattern was bipolar where the two heterozygotes are different but the two homozygotes are not, consistently for all affected traits (Figure 1). The bipolar pattern is also reflected in the absence of an additive genetic effect, which is required for either paternal or maternal expression [8]. This is somewhat surprising as one might have expected a parental expression pattern (either paternal or maternal expression) since these patterns are commonly assumed to be more prevalent. An additional imprinted locus was found for body weight on chromosome 12. Figure 1 shows two different patterns of bipolar imprinting expression. While body weight shows a pattern with a higher value for the maternal heterozygote (B/A), glycolytic potential and glycogen content have higher values for the paternal heterozygote (A/B).


Genomic imprinting and genetic effects on muscle traits in mice.

Kärst S, Vahdati AR, Brockmann GA, Hager R - BMC Genomics (2012)

Imprinting patterns for A) body weight on Mc12.1,B) glycolytic content and C) glycolytic potential on the pleiotropic QTL Mc19.1. The pattern of imprinting effect is bipolar expression for all the traits. We have used uncorrected trait means (i.e. before adjustment for direction of cross and sex) to illustrate the magnitude of effects in this figure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475036&req=5

Figure 1: Imprinting patterns for A) body weight on Mc12.1,B) glycolytic content and C) glycolytic potential on the pleiotropic QTL Mc19.1. The pattern of imprinting effect is bipolar expression for all the traits. We have used uncorrected trait means (i.e. before adjustment for direction of cross and sex) to illustrate the magnitude of effects in this figure.
Mentions: We discovered genomic imprinting effects located on chromosome 19 with a strong effect on glycolytic potential and content. The imprinting pattern was bipolar where the two heterozygotes are different but the two homozygotes are not, consistently for all affected traits (Figure 1). The bipolar pattern is also reflected in the absence of an additive genetic effect, which is required for either paternal or maternal expression [8]. This is somewhat surprising as one might have expected a parental expression pattern (either paternal or maternal expression) since these patterns are commonly assumed to be more prevalent. An additional imprinted locus was found for body weight on chromosome 12. Figure 1 shows two different patterns of bipolar imprinting expression. While body weight shows a pattern with a higher value for the maternal heterozygote (B/A), glycolytic potential and glycogen content have higher values for the paternal heterozygote (A/B).

Bottom Line: Imprinting is increasingly recognized as an important source of variation in complex traits, however, its role in explaining variation in muscle and physiological traits, especially those of commercial value, is largely unknown compared with genetic effects.Surprisingly, variation in glycogen content and potential was only modulated by imprinting effects.Further, in contrast to general assumptions, our results show that genomic imprinting can impact physiological traits measured at adult stages and that the expression does not have to follow the patterns of paternal or maternal expression commonly ascribed to imprinting effects.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Crop and Animal Sciences, Humboldt-University Berlin, Berlin, Germany.

ABSTRACT

Background: Genomic imprinting refers to parent-of-origin dependent gene expression caused by differential DNA methylation of the paternally and maternally derived alleles. Imprinting is increasingly recognized as an important source of variation in complex traits, however, its role in explaining variation in muscle and physiological traits, especially those of commercial value, is largely unknown compared with genetic effects.

Results: We investigated both genetic and genomic imprinting effects on key muscle traits in mice from the Berlin Muscle Mouse population, a key model system to study muscle traits. Using a genome scan, we first identified loci with either imprinting or genetic effects on phenotypic variation. Next, we established the proportion of phenotypic variation explained by additive, dominance and imprinted QTL and characterized the patterns of effects. In total, we identified nine QTL, two of which show large imprinting effects on glycogen content and potential, and body weight. Surprisingly, all imprinting patterns were of the bipolar type, in which the two heterozygotes are different from each other but the homozygotes are not. Most QTL had pleiotropic effects and explained up to 40% of phenotypic variance, with individual imprinted loci accounting for 4-5% of variation alone.

Conclusion: Surprisingly, variation in glycogen content and potential was only modulated by imprinting effects. Further, in contrast to general assumptions, our results show that genomic imprinting can impact physiological traits measured at adult stages and that the expression does not have to follow the patterns of paternal or maternal expression commonly ascribed to imprinting effects.

Show MeSH
Related in: MedlinePlus