Date of Award

1-1-2018

Embargo Period

4-12-2023

Document Type

Thesis

Degree Name

Master of Biomedical Science

Department

Pathology and Laboratory Medicine

College

College of Graduate Studies

First Advisor

Victoria J. Findlay

Second Advisor

David P. Turner

Third Advisor

Kristi L. Helke

Fourth Advisor

Sarah N. Taylor

Fifth Advisor

Robin Muise-Helmericks

Abstract

Breastfeeding is the optimal method for mothers to deliver nutrients to her newborn(s), providing both short- and long-term health benefits. Unfortunately, only 24% of infants receive exclusive breastfeeding for the first six months, as recommended by the World Health Organization and American Academy of Pediatrics, with the most often cited reason for this being “low milk supply”. Low Milk Supply (LMS) is a real and growing problem in the United States, with at least 5-10% (approximately 200,000) mothers experiencing LMS in the US each year. We previously observed temporal expression of miR-204 during normal mammary gland development, which led us to generate a unique doxycycline-inducible miR-204 transgenic mouse model to temporally overexpress miR-204 in the mammary ductal epithelium. We observed a lactation defect in nursing dams characterized by significantly reduced pup weight, aberrant mammary gland morphology, and reduced volume of milk production. This led to the hypothesis that dysregulation of miR-204 expression results in LMS through the inhibition of the Milk Protein Synthesis (MPS) Pathway. In our in vivo analysis, we collected mammary gland tissue and milk from miR-204 transgenic (miR-204 Tg) and control (non-Tg) mice at different stages of lactation and performed immunohistochemistry and quantitative polymerase chain reaction analysis for components within the MPS Pathway and miR-204. We show that miR-204 is temporally expressed in mouse tissue and milk. We show reduced activation of the MPS Pathway in miR-204 transgenic mice through reduced IHC staining for components within the MPS Pathway and reduced levels of both milk proteins, WAP and CSN2. In our in vitro approach, we stably infected HC11 cells with miR-204, treated with lactogenic hormones, and performed qPCR analysis for β-casein. We show that miR-204 reduces activation of the MPS Pathway and production of β-casein. We collected milk from women with known sufficient milk supply and LMS and measured levels of miR-204. We show that we areable to detect miR-204 in human breast milk and demonstrate elevated miR-204 levels in women with LMS. Our data suggests that miR-204 may be a useful biomarker in milk to detect an LMS in women.

Rights

All rights reserved. Copyright is held by the author.

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