Characterisation of energy metabolism during lactation in cellular and mouse models

Maternal metabolic diseases such as diabetes and obesity are associated with lactation insufficiency and breastfeeding failure. The goal of this project is to undertake discovery science to characterise how molecules and tissues involved in energy metabolism contribute to the optimal supply of breast milk. The first part of this project will investigate the adiponectin receptor 1 (AdiporR1), a highly expressed hormone receptor in human mammary epithelial cells during pregnancy and lactation. AdiporR1 detects alterations in an adipocyte-derived hormone known as adiponectin, which has been reported to upregulate mitochondrial biogenesis in tissues such as skeletal muscle. The role of AdiporR1 in the mammary gland is uncertain, and this will be investigated using the MCF-10A human mammary epithelial cell line, which expresses AdiporR1. Cultured MCF-10A cells will be stimulated with recombinant adiponectin, and mitochondrial abundance and function assessed using mitochondrial DNA copy number and enzyme activity assays, respectively. RNA silencing of AdiporR1 in MCF-10A cells will be performed to determine whether this abrogates any observed mitochondrial effects of adiponectin. If AdipoR1 is shown to influence mammary epithelial cell function, then AdipoRon, a commercially available orally active adiponectin receptor agonist will be administered to female wild-type mice during pregnancy and the early post-partum period to assess the effect on lactation, as measured by pup growth prior to weaning. The second part of this project will identify which hormones are involved in regulating tissues involved in energy metabolism during lactation. Age-matched pregnant and lactating adult female mice will undergo metabolic profiling by assessment of glucose tolerance and insulin sensitivity, plasma lipids and body fat composition. Plasma will be obtained for measurement of key lactogenic and metabolic hormones. Relevant tissues e.g. adipose tissue, skeletal muscle, pancreatic islets, and mammary glands will be dissected from these mice for RNA-sequencing. A global survey of hormone receptor and signalling protein expression will be undertaken in these tissues, and correlated with hormonal and metabolic changes occurring during the transition from pregnancy to lactation. Thus, these studies aim to determine how maternal tissues adapt to the metabolic demands of breastfeeding, and also to provide a basis for understanding how diseases such as diabetes and obesity lead to lactation insufficiency.