Uptake and Function Studies of Maternal Milk-derived MicroRNAs

Area of Science:

• Molecular Biology
• Developmental Biology
• Nutritional Science

Background:

• MicroRNAs (miRNAs) regulate gene expression and are found in body fluids.
• The function of extracellular miRNAs from external sources, like milk, is debated.
• High levels of miRNAs are present in lactating mouse milk.

Purpose of the Study:

• To investigate the intestinal uptake and functional role of milk-derived microRNAs in newborn mice.
• To determine if exogenous miRNAs from milk can be absorbed and regulate gene expression in neonates.

Main Methods:

• Utilized genetic models of knockout mice for specific microRNAs (miR-375 and miR-200c/141).
• Administered milk from wild-type foster mothers to knockout neonates.
• Analyzed miRNA levels in intestinal epithelium, blood, liver, and spleen.

Main Results:

• No evidence of microRNA uptake was found in the intestinal epithelium, blood, liver, or spleen.
• Hepatocyte levels of miR-375 were below the threshold required for gene regulation.
• Milk microRNAs were rapidly degraded in the intestinal fluid of newborn mice.

Conclusions:

• Milk-derived microRNAs are not absorbed by the intestinal epithelium in newborn mice.
• Exogenous microRNAs in milk likely serve a nutritional function rather than a gene-regulatory role.
• Rapid degradation prevents functional gene regulation by milk microRNAs in neonates.