Does Breast Milk Contribute to Gene Silencing?

February 23, 2021
Human milk is rich in effector molecules, which lead to gene silencing. Today, you'll understand what this mechanism is about, and why it's important for your baby.

As we’ve mentioned before, gene silencing is a sophisticated mechanism, which controls tissue functions. Human milk contains silencing molecules, and this represents a milestone for the physiological basis of breastfeeding. As a result, breast milk isn’t considered a simple food anymore. In fact, it’s a sophisticated communication system between mothers and their babies.

In this article, we’ll talk about how breast milk silencing molecules prepare the baby’s genetic programming.

What is the mechanism of gene silencing?

To explain this mechanism, it’s necessary to remember that DNA and RNA are two types of nucleic acids. Each type corresponds to long molecules, which link to smaller molecules. Depending on this specific sequence, two nucleic acid chains can recognize each other and join to form a double chain.

On the one hand, DNA sequences of basis form an “original model” of gene sequences. On the other hand, each gene’s information is copied into a messenger RNA (mRNA). This process of copying a gene from the DNA into mRNA is the first step to form proteins. 

Gene silencing happens though mRNA interference or block. This is an innate process, which destroys the copy of the gene that the mRNA contains.

Does Breast Milk Contribute to Gene Silencing?

What’s the process like?

During silencing, small sequences of RNA interference (RNAi) join the mRNA, and this duo is detected and destroyed. It’s important to know that RNAi and mRNA need to be complementary in order to join together. Therefore, this is a gene-specific process. So far, 1080 different silencing molecules have been detected in humans, and 400 of those molecules are in breast milk.

What is the function of gene silencing during breastfeeding?

At first, when people discovered silencing, they considered it a defense mechanism to silence harmful mRNA, such as viruses. However, now we know that silencing helps regulate really complex processes.

In the case of breastfed babies, it helps regulate immune responses and cell development. Without a doubt, both functions are extremely important for the development of the baby.

How do these silencing molecules travel through breast milk?

Milk RNAi travels within small lipid capsules called exosomes and within milk fat globules. These exosomes derive from the epithelial cells of the mammary glands.

Does Breast Milk Contribute to Gene Silencing?

Thanks to this special packaging, exosomes integrate easily with intestinal cells. After this, they can reach two different destinations: they can regulate the function of the intestinal cell, or go through the intestine and reach the blood flow, acting as a target cell.

More information you’d like to know about silencing molecules

  • Almost every living cell synthesizes and secretes exosomes. Each of them do it with their own amount of RNAi, which regulates gene expression and metabolism.
  • This mechanism mediated by exosomes can act on neighbor cells from the same tissue, or it can act on distant cells, travelling through blood.
  • RNAi regulate the expression and metabolism of approximately 60% of human genes.
  • Scientists have proven that inappropriate RNAi production can lead to the development of several diseases.
  • Baby formula is deficient RNAi exosomes.
  • A wide variety of organisms, like animals, plants and fungus produce and secrete RNAi exosomes.
  • The knowledge about the way RNAi works is being applied to block genes for therapeutic and research purposes.
  • Benmoussa, A., & Provost, P. (2019). Milk microRNAs in health and disease. Comprehensive Reviews in food science and food safety, 18(3), 703-722.
  • Kelleher, S. L., Gagnon, A., Rivera, O. C., Hicks, S. D., Carney, M. C., & Alam, S. (2019). Milk-derived miRNA profiles elucidate molecular pathways that underlie breast dysfunction in women with common genetic variants in SLC30A2. Scientific reports9(1), 1-13.
  • Rani, P., Yenuganti, V. R., Shandilya, S., Onteru, S. K., & Singh, D. (2017). MiRNAs: The hidden bioactive component of milk. Trends in Food Science & Technology65, 94-102.
  • Zempleni, J., Aguilar-Lozano, A., Sadri, M., Sukreet, S., Manca, S., Wu, D., … & Mutai, E. (2017). Biological activities of extracellular vesicles and their cargos from bovine and human milk in humans and implications for infants. The Journal of nutrition, 147(1), 3-10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5177735/