title: Intronic parent-of-origin dependent differential methylation at the Actn1 gene is conserved in rodents but is not associated with imprinted expression.
abstract: Parent-of-origin differential DNA methylation has been associated with regulation of the preferential expression of paternal or maternal alleles of imprinted genes. Based on this association, recent studies have searched for parent-of-origin dependent differentially methylated regions in order to identify new imprinted genes in their vicinity. In a previous genome-wide analysis of mouse brain DNA methylation, we found a novel differentially methylated region in a CpG island located in the last intron of the alpha 1 Actinin (Actn1) gene. In this region, preferential methylation of the maternal allele was observed; however, there were no reports of imprinted expression of Actn1. Therefore, we have tested if differential methylation of this region is common to other tissues and species and affects the expression of Actn1. We have found that Actn1 differential methylation occurs in diverse mouse tissues. Moreover, it is also present in other murine rodents (rat), but not in the orthologous human region. In contrast, we have found no indication of an imprinted effect on gene expression of Actn1 in mice: expression is always biallelic regardless of sex, tissue type, developmental stage or isoform. Therefore, we have identified a novel parent-of-origin dependent differentially methylated region that has no apparent association with imprinted expression of the closest genes. Our findings sound a cautionary note to genome-wide searches on the use of differentially methylated regions for the identification of imprinted genes and suggest that parent-of-origin dependent differential methylation might be conserved for functions other that the control of imprinted expression.
authors.affiliation: Curriculum in Genetics and Molecular Biology, Department of Genetics, Lineberger Comprehensive Cancer Center and Carolina Center for Genome Sciences of the University of North Carolina (UNC), Chapel Hill, NC, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Calaway
authors.forename: José Ignacio
authors.initials: JI
authors.lastname: Domínguez
authors.forename: Megan E
authors.initials: ME
authors.lastname: Hanson
authors.forename: Ezequiel C
authors.initials: EC
authors.lastname: Cambranis
authors.forename: Fernando
authors.initials: F
authors.lastname: Pardo-Manuel de Villena
authors.forename: Elena
authors.initials: E
authors.lastname: de la Casa-Esperon
mesh_terms: D000185:Actinin / Q000235:genetics*; D000483:Alleles; D000818:Animals; D018899:CpG Islands; D019175:DNA Methylation; D005260:Female; D015870:Gene Expression; D018392:Genomic Imprinting / Q000235:genetics*; D006801:Humans; D007438:Introns; D008297:Male; D051379:Mice; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C528567:Actn1 protein, mouse; D000185:Actinin