Although the roles of progesterone and prolactin in mammary gland development have been extensively studied, the roles of Insulin, IGF1 and 1GF2 have received much less attention. The Neville laboratory recently found that a null mutation of the insulin receptor (IR) specifically in the secretory epithelium both impedes proliferative activity in eariy pregnancy and largely inhibits secretory differentiation in late pregnancy. We hypothesize that this receptor and one or more of its ligands are important modulators of mammary differentiation. Similariy, extensive work with the progesterone receptor (PR) in the mammary gland has shown that progesterone and PR are necessary for alveolar proliferation and development. There is also evidence that IR and PR work together to modulate each other's activity, although almost nothing is known about the mechanisms. In this project Dr. Neville and Dr. Edwards, an expert on PR, will work with two experts in metabolism, Drs. Carrie McCurdy and Paul MacLean, to investigate this new area. In vitro experiments will utilize unique 3D acinar cultures of mammary epithelial cells from virgin and 15 day pregnant mice to elucidate the molecular mechanisms by which these two regulatory pathways direct both proliferation and differentiation in the mammary gland. The investigators will also use mouse models of hypoinsulinemia and hyperinsulinemia to examine how conditions such as starvation, diabetes and obesity impinge on these pathways, and through them on milk secretion. Obesity, an increasingly common condition in most developing countries, is often associated with lactation failure in a population where breastfeeding is likely to be most beneficial to the infant. Understanding the mechanisms by which obesity alters mammary development and lactation competence may provide new therapeutic modalities that will enhance breastfeeding success.

Public Health Relevance

Obesity is a primary health concern worldwide that negatively impacts breastfeeding performance. Normally plasma insulin levels rise during pregnancy;preliminary data from our institution show that the rise is higher in obese women. Our studies offer a possible mechanistic link between the effects of insulin upon mammary development, lactation failure, and breast cancer development providing us with the basis for both diagnostic and potential therapeutic interventions.

National Institute of Health (NIH)
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Research Program Projects (P01)
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Special Emphasis Panel (ZHD1)
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University of Colorado Denver
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Rudolph, Michael C; Jackman, Matthew R; Presby, David M et al. (2018) Low Neonatal Plasma n-6/n-3 PUFA Ratios Regulate Offspring Adipogenic Potential and Condition Adult Obesity Resistance. Diabetes 67:651-661
Checkley, L Allyson; Rudolph, Michael C; Wellberg, Elizabeth A et al. (2017) Metformin Accumulation Correlates with Organic Cation Transporter 2 Protein Expression and Predicts Mammary Tumor RegressionIn Vivo. Cancer Prev Res (Phila) 10:198-207
Rudolph, M C; Young, B E; Lemas, D J et al. (2017) Early infant adipose deposition is positively associated with the n-6 to n-3 fatty acid ratio in human milk independent of maternal BMI. Int J Obes (Lond) 41:510-517
Baumgartner, Heidi K; Rudolph, Michael C; Ramanathan, Palaniappian et al. (2017) Developmental Expression of Claudins in the Mammary Gland. J Mammary Gland Biol Neoplasia 22:141-157
Heinz, Richard E; Rudolph, Michael C; Ramanathan, Palani et al. (2016) Constitutive expression of microRNA-150 in mammary epithelium suppresses secretory activation and impairs de novo lipogenesis. Development 143:4236-4248
Grimm, Sandra L; Hartig, Sean M; Edwards, Dean P (2016) Progesterone Receptor Signaling Mechanisms. J Mol Biol 428:3831-49
TreviƱo, Lindsey S; Bolt, Michael J; Grimm, Sandra L et al. (2016) Differential Regulation of Progesterone Receptor-Mediated Transcription by CDK2 and DNA-PK. Mol Endocrinol 30:158-72
Sladek, Celia D; Stevens, Wanida; Song, Zhilin et al. (2016) The ""metabolic sensor"" function of rat supraoptic oxytocin and vasopressin neurons is attenuated during lactation but not in diet-induced obesity. Am J Physiol Regul Integr Comp Physiol 310:R337-45
Libby, Andrew E; Bales, Elise; Orlicky, David J et al. (2016) Perilipin-2 Deletion Impairs Hepatic Lipid Accumulation by Interfering with Sterol Regulatory Element-binding Protein (SREBP) Activation and Altering the Hepatic Lipidome. J Biol Chem 291:24231-24246
Rudolph, Michael C; Young, Bridget E; Jackson, Kristina Harris et al. (2016) Human Milk Fatty Acid Composition: Comparison of Novel Dried Milk Spot Versus Standard Liquid Extraction Methods. J Mammary Gland Biol Neoplasia 21:131-138

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