# piRNAs as Potential Regulators of Mammary Gland Development and Pathology in Livestock

## TL;DR

This paper explores how piRNAs might regulate mammary gland development and disease in dairy cows, offering new insights for livestock research and applications.

## Contribution

The paper introduces a novel perspective on piRNA functions in bovine mammary biology and mastitis, highlighting their potential for practical applications in animal husbandry.

## Key findings

- piRNAs are key regulators of reproductive development in livestock species.
- piRNAs may influence mammary gland development and mastitis in dairy cows.
- The paper suggests piRNAs could serve as targets for improving mammary health in cattle.

## Abstract

PIWI-interacting RNAs (piRNAs) have been demonstrated to maintain transposon silencing and regulate reproductive development and disease progression by binding to PIWI proteins. However, research on piRNAs in livestock animals is still in its infancy, with only preliminary studies available regarding their roles in the reproduction of swine, bovine, and ovine species. Given the regulatory mechanisms of piRNAs in mammary cancer and inflammation, as well as the established roles of other non-coding RNAs (ncRNAs) in mammary development, this paper focuses on the dairy cow mammary system to explore the potential functions of piRNAs in mammary development and mastitis. This review offers a novel perspective on mammary gland biology in livestock and provides a theoretical foundation for understanding the role of piRNAs in mammary gland development and associated diseases, representing significant value for both basic research and practical applications.

PiRNAs are a subclass of non-coding RNAs, 26–31 nucleotides (nt) in length, that form regulatory complexes through their interaction with PIWI proteins. Studies in model organisms have demonstrated that piRNAs play crucial roles in tissue development and in predicting disease outcomes, positioning them as promising targets for developmental regulation and therapeutic intervention. In contrast, research on piRNAs in animal husbandry is still in its early stages and has not received sufficient attention. Despite this, the few studies available in livestock research have revealed that piRNAs serve as key regulators of reproductive development, underscoring their significant regulatory potential in farm animals and justifying further investigation. Accordingly, this review uses the bovine mammary gland as an exemplary case to summarize the progress in piRNA research related to mammary development and disease. The role of piRNAs in regulating breast cancer stem cell proliferation and modulating inflammatory progression is a highly active area of research. We hypothesize that piRNAs may play a potential role in regulating both mammary gland development and mastitis, making them promising targets for enhancing mammary development and overall health in dairy cattle and providing a theoretical foundation for further piRNA applications in animal husbandry.