%0 Journal Article
%T Selected imprinting of INS in the marsupial
%A Jessica M Stringer
%A Shunsuke Suzuki
%A Andrew J Pask
%A Geoff Shaw
%A Marilyn B Renfree
%J Epigenetics & Chromatin
%D 2012
%I BioMed Central
%R 10.1186/1756-8935-5-14
%X INS was expressed in the mammary gland and significantly increased, while IGF2 decreased, during established milk production. Insulin and IGF2 were both detected in the mammary gland macrophage cells during early lactation and in the alveolar cells later in lactation. Surprisingly, INS, which was thought only to be imprinted in the therian yolk sac, was imprinted and paternally expressed in the liver of the developing young, monoallelically expressed in the tammar mammary gland and biallelic in the stomach and intestine. The INS transcription start site used in the liver and mammary gland was differentially methylated.This is the first study to identify tissue-specific INS imprinting outside the yolk sac. These data suggest that there may be an advantage of selective monoallelic expression in the mammary gland and that this may influence the growth of the postnatal young. These results are not consistent with the parental conflict hypothesis, but instead provide support for the maternal¨Cinfant co-adaptation hypothesis. Thus, imprinting in the mammary gland maybe as critical for postnatal growth and development in mammals as genomic imprinting in the placenta is prenatally.Genomic imprinting is an epigenetic modification to the DNA that regulates the expression of selected genes from only one parental allele. In vertebrates, imprinting is restricted to the therian (marsupial and eutherian) mammals but as yet no imprinted genes have been identified in monotremes [1,2]. Thus mammalian genomic imprinting is thought to have evolved after the therian¨Cmonotreme divergence. In mice and humans, most imprinted genes are expressed in the placenta, some of which are exclusively imprinted in this organ [3-7]. Although the significance of imprinted gene expression is still debated, many imprinted genes regulate growth and nutrient provisioning to the developing fetus [8-11]. Potentially, therefore, any organ that regulates growth via nutrient exchange with the developing young ma
%K Genomic imprinting
%K Mammary gland
%K Lactation
%K Marsupial
%K Insulin
%K Co-adaptation
%U http://www.epigeneticsandchromatin.com/content/5/1/14