Callipyge sheep exhibit extreme postnatal muscle hypertrophy in the loin and hindquarters as a result of a single nucleotide polymorphism (SNP) in the imprinted DLK1-DIO3 domain on ovine chromosome 18. The callipyge SNP up-regulates the expression of surrounding transcripts when inherited in cis without altering their allele-specific imprinting status. The callipyge phenotype exhibits polar overdominant inheritance since only paternal heterozygous animals have muscle hypertrophy. Two studies were conducted profiling gene expression in lamb muscles to determine the down-stream effects of over-expression of paternal allele-specific DLK1 and RTL1 as well as maternal allele-specific MEG3, RTL1AS and MEG8, using Affymetrix bovine expression arrays. A total of 375 transcripts were differentially expressed in callipyge muscle and 25 transcripts were subsequently validated by quantitative PCR. The muscle-specific expression patterns of most genes were similar to DLK1 and included genes that are transcriptional repressors or affect feedback mechanisms in β-adrenergic and growth factor signaling pathways. One gene, phosphodiesterase 7A had an expression pattern similar to RTL1 expression indicating a biological activity for RTL1 in muscle. Only transcripts that localize to the DLK1-DIO3 domain were affected by inheritance of a maternal callipyge allele. Callipyge sheep are a unique model to study over expression of both paternal allele-specific genes and maternal allele-specific non-coding RNA with an accessible and nonlethal phenotype. This study has identified a number of genes that are regulated by DLK1 and RTL1 expression and exert control on postnatal skeletal muscle growth. The genes identified in this model are primary candidates for naturally regulating postnatal muscle growth in all meat animal species, and may serve as targets to ameliorate muscle atrophy conditions including myopathic diseases and age-related sarcopenia.


Mathematics and Statistics

Keywords and Phrases

Membrane Protein; Protein Dlk1; Unclassified Drug; Membrane Protein; Muscle Protein, Animal Tissue; Article; Controlled Study; Gene Expression; Gene Expression Profiling; Gene Frequency; Lamb; Muscle Growth; Muscle Hypertrophy; Nonhuman; Phenotype; Protein Domain; Protein Localization; Quantitative Analysis; Signal Transduction; Upregulation; Allele; Alternative RNA Splicing; Animal; Biological Model; Cluster Analysis; DNA Microarray; Gene Expression Regulation; Metabolism; Muscle; Mutation; Sheep; Single Nucleotide Polymorphism, Animalia; Bovinae; Ovis; Ovis Aries, Alleles; Alternative Splicing; Animals; Cluster Analysis; Gene Expression Regulation; Membrane Proteins; Models, Biological; Models, Genetic; Muscle Proteins; Muscles; Mutation; Oligonucleotide Array Sequence Analysis; Polymorphism, Single Nucleotide; Sheep; Signal Transduction

International Standard Serial Number (ISSN)


Document Type

Article - Journal

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Final Version

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© 2009 The Authors, All rights reserved.

Publication Date

01 Jan 2009