MicroRNA profiles were altered in neonatal piglet mammary glands following postnatal infant formula feeding

Authors: LIN, HAIXIA - Arkansas Children'S Nutrition Research Center (ACNC); CHAUDHURY, MOUSUMI - Arkansas Children'S Nutrition Research Center (ACNC); SHARMA, NEHA - Arkansas Children'S Nutrition Research Center (ACNC); BHATTACHARYYA, SUDEEPA - University Arkansas For Medical Sciences (UAMS); ELOLIMY, AHMED - Arkansas Children'S Nutrition Research Center (ACNC); YERUVA, LAXMI - Arkansas Children'S Nutrition Research Center (ACNC); RONIS, MARTIN JJ - Louisiana State University Medical Center; MERCER, KELLY - Arkansas Children'S Nutrition Research Center (ACNC)

Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2020
Publication Date: 4/8/2020
Citation: Lin, H., Chaudhury, M., Sharma, N., Bhattacharyya, S., Elolimy, A.A., Yeruva, L., Ronis, M., Mercer, K.E. 2020. MicroRNA profiles were altered in neonatal piglet mammary glands following postnatal infant formula feeding. Journal of Nutritional Biochemistry. https://doi.org/10.1016/j.jnutbio.2020.108397.
DOI: https://doi.org/10.1016/j.jnutbio.2020.108397

Interpretive Summary: Diet is a potent regulator of how the DNA code is expressed (gene expression) in the body's tissues, but the specific signals and molecular mechanisms remain to be elaborated. This may be especially important in early development. One potential mechanism by which early-life diet influences gene expression is through modulation of cellular molecules called microRNAs (miRNAs). In the current studies, we aimed to determine if milk- and soy-based formula feeding influenced miRNA profiles in mammary glands of neonatal piglets when compared to sow-fed piglets, to determine if altered miRNAs played a crucial role in mammary development. Female neonatal piglets were fed milk- and soy-based formulas from postnatal day 2 to 21. We found that formula feeding altered mammary miRNA signatures; downregulation of miR-1, -128, -133a, -193b, -206, and -27a was negatively correlated with expression of genes associated with enhanced cell proliferation and/or increased cholesterol synthesis in the developing mammary gland. It may further unravel the mechanisms that explain why formula feeding heightens mammary proliferative status and increases a marker of tissue growth called terminal end buds. To our knowledge, this is the first report showing the modulation by infant formula on miRNA expressions in the early mammary gland. It also provides insights into neonatal dietary modulation of a potential miRNA-mRNA regulatory network that regulates the body's tissues under physiological conditions.

Technical Abstract: Postnatal dietary modulation of microRNAs (miRNAs) and effects on miRNA-mRNA interactions in tissues remain unknown. This study aimed to investigate whether dietary factors (formula vs. breastfeeding) affect mammary miRNA expression, and determine if these changes are concurrent with developmental alterations of the mammary gland in neonatal piglets. Female Yorkshire/Duroc piglets were fed sow's milk or cow's milk- or soy-based infant formula (from postnatal day 2 to day 21; n=6/group). Differentially expressed miRNAs were determined using mammary miRNA profiling, followed by miRNA and mRNA expressions characterized by quantitative RT-PCR. Milk and soy formulas reduced expressions of miR-1, -128, -133a, -193b, -206, and -27a; miRNA downregulation altered mRNA expressions of genes (e.g., Ccnd1, Tgfb3, Igf1r, and Tbx3) that were consistent with enhanced cell proliferation and suppressed apoptotic processes in the developing mammary gland. Interestingly, downregulation of miR-1, -128, and -27a, also correlated with increased mRNA genes such as Hmgcs and Hmgcr encoding cholesterol synthesis in the mammary glands in response to lower circulating cholesterol levels. Infant formula feeding affected mammary miRNA profiles in neonatal piglets, concurrent with increased expression of cell proliferation and cholesterol synthesis genes, suggesting early nutritional modulation of miRNAs may contribute to regulation of proliferative status and cholesterol homeostasis of developing mammary glands during infancy.