RNA modifications in female reproductive physiology and disease: emerging roles and clinical implications.

Background: RNA modifications, collectively known as the epitranscriptome, represent the third layer of gene regulation, influencing gene expression at transcriptional, post-transcriptional, and translational levels. RNA-modifying proteins (RMPs), including writers, erasers, and readers, are responsible for depositing, removing, and recognizing chemical modifications on RNA molecules. These modifications play a crucial role in linking molecular processes to cellular functions. Over the past few decades, a growing body of laboratory evidence, alongside advances in sequencing technologies, has uncovered connections between aberrant RNA modifications and reproductive disorders, highlighting their emerging roles in female fertility. Given the rapid expansion of epitranscriptomic research in female reproduction, a comprehensive review is needed to summarize the broader impacts of various RNA modifications, rather than focusing on individual RNA modifications alone.

Objective and rationale: This review aims to elucidate the progress in understanding the role of RNA modifications in reproductive biology and how their dysregulations contribute to infertility-related conditions, such as polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI), and endometriosis. Special focus will be given to RNA modifications in coding RNAs, particularly those linked to female fertility and supported by solid evidence. The ultimate objective is to explore how targeting the RNA-modification machinery can lead to the development of novel therapeutic interventions for restoring fertility.

Search methods: We conducted a thorough review of peer-reviewed original research articles and reviews published over the past two decades using the PubMed search engine. Keywords included terms related to RNA modifications, such as 'N6-methyladenosine (m6A)', 'N4-acetylcytidine (ac4C)', and 'adenosine-to-inosine (A-I) editing', combined with terms related to female reproduction, such as 'ovary', 'oocyte', and 'embryo'. Additional relevant search phrases were also utilized to ensure comprehensive coverage of the topic.

Outcomes: RNA modification has emerged as a transformative area in reproductive biology, with our understanding of the epitranscriptome growing rapidly due to significant advances in high-throughput sequencing technologies. Regulatory proteins play a crucial role in the correct deposition and functional implementation of RNA modifications. Knockout animal models have identified a broad, though still incomplete, list of RNA modifications involved in mammalian reproductive processes. These include prevalent modifications in mRNA, such as m6A, as well as A-I editing, and, to a lesser extent, 5-methylcytosine (m5C) and ac4C. These regulatory mechanisms impact various reproductive functions, including folliculogenesis, oocyte maturation, fertilization, and embryo development. Dysregulation of RNA modifications may exacerbate infertility-related conditions, such as POI, PCOS, and endometriosis. Although clinical investigations are still in their early stages, RNA modifications show great promise as diagnostic biomarkers and therapeutic targets, with the potential to improve fertility and reproductive health outcomes.

Wider implications: This review explores a relatively underexamined area of epitranscriptomic research in female reproduction, offering the potential to significantly advance our understanding of reproductive biology. It underscores the clinical relevance of RNA modifications in infertility-related disorders and identifies potential biomarkers, as well as RMP-targeted therapies, that could shape future clinical decision-making and personalized treatments. These insights are crucial for reproductive clinicians and embryologists, presenting new avenues for diagnosis and therapeutic interventions in reproductive medicine.

Registration number: N/A.