UNASSIGNED: Endocrine regulation of milk protein gene expression in marsupials and eutherians is well studied. However, the evolution of this complex regulation that began with monotremes is unknown. Monotremes represent the oldest lineage of extant mammals and the endocrine regulation of lactation in these mammals has not been investigated. Here we characterised the proximal promoter and hormonal regulation of two @entity429 milk protein genes, Beta-lactoglobulin (BLG), a whey protein and monotreme lactation protein (MLP), a monotreme specific milk protein, using in vitro reporter assays and a @entity291 mammary epithelial cell line (BME-UV1). Insulin and @entity619 alone provided partial induction of MLP, while the combination of insulin, @entity619 and @entity70220 was required for maximal induction. Partial induction of BLG was achieved by insulin, @entity619 and @entity70220 alone, with maximal induction using all three hormones. @entity429 MLP and BLG core promoter regions comprised transcription factor binding sites (e.g. STAT5, @entity70221 and @entity70222 ) that were conserved in marsupial and eutherian lineages that regulate caseins and whey protein gene expression. Our analysis suggests that insulin, @entity619 and/or @entity70220 alone can regulate the @entity429 MLP and BLG gene expression, unlike those of therian lineage. The induction of @entity429 milk protein genes by lactogenic hormones suggests they originated before the divergence of marsupial and eutherians.

Hormonal regulation of XXXX Beta-lactoglobulin and monotreme lactation protein genes.

@entity70222 :: ('100078506(Tax:9258)', 'Gene') :: ['C/EBPa'] @entity619 :: ('MESH:D003907', 'Chemical') :: ['dexamethasone'] @entity70221 :: ('100074914(Tax:9258)', 'Gene') :: ['NF-1'] @entity70220 :: ('100083427(Tax:9258)', 'Gene') :: ['prolactin'] @entity291 :: ('9913', 'Species') :: ['bovine'] @entity429 :: ('9258', 'Species') :: ['Platypus', 'platypus']
@entity429 :: (9258,Species) :: ['platypus']
