Designing effective RNA therapies for oocyte maturation

ABSTRACT
Infertility is a major reproductive health issue that affects ~12% of reproductively aged women in the United
States. Approximately 1-3% of infertile or subfertile women have oocytes that arrest in meiosis or shortly after
fertilization due to genetic variants. Unfortunately, there are no therapies for women experiencing infertility due
to oocyte arrest. Strategies to restore oocyte maturation in women with oocyte arrest are of dire need in order
to give these women fertility options. An emerging class of therapies, called mRNA therapeutics, utilize in vitro
synthesized mRNA as a treatment for diseases and for vaccines such as the SARS-CoV-2 mRNA vaccines,
but the safety and efficacy has not been explored in infertility. Microinjection of RNA into oocytes is an
established tool that has enabled discovery of critical aspects of oocyte biology, but it could also be used as a
therapeutic, particularly in women with oocyte arrest. Two recent studies successfully generated blastocysts in
oocytes from women with genetic variants causing oocyte arrest, following the injection of in vitro synthesized
wild-type RNA during assisted reproductive procedures. RNA therapies represent a novel treatment strategy
for women experiencing oocyte arrest, however, rigorous testing is needed before they become an assisted
reproductive technology. Considering the unique RNA processing and transcriptional quiescence of fully grown
oocytes it is critical to understand how oocytes process exogenous RNA therapeutic molecules. Furthermore,
synthetic therapeutic mRNA contain RNA modifications that promote RNA stability, translation, and reduce
immune stimulation. Recently, our work and others have implicated RNA modifications as playing an important
regulatory role in RNA stability and translation in oocytes. However, the impact of multiple RNA modifications
on RNA stability, translation, and oocyte maturation has not been examined. Our goal here is to test how RNA
modifications impact the function of mRNA therapeutics designed to rescue oocyte maturation defects. To
understand how RNA therapeutics are processed by the oocyte and how they impact oocyte maturation and
fertility, we will use a genetic knockout mouse model of the Protein Associated with Topoisomerase II Homolog
2 (Patl2 gene), which results in oocyte maturation arrest. Mice lacking PATL2 protein phenocopy women with
genetic defects in Patl2, and have oocytes that fail to mature, so we predict that microinjection of an RNA
therapeutic for Patl2 will restore oocyte maturation, fertilization, and birth. We will determine the effects of RNA
modifications on stability and translation of therapeutic Patl2 RNA. Our studies have the potential to reveal
novel aspects of RNA modifications in oocyte RNA processing and translation, as well as establish groundwork
for future studies testing the safety and efficacy of RNA therapeutics to treat female infertility due to oocyte
arrest.

Grant Number: 6R21HD112742-02
NIH Institute/Center: NIH
Principal Investigator: Nehemiah Alvarez