Transcriptional profiling of cumulus cells from FLI-matured porcine oocytes identifies junctional genes as key components in oocyte maturation

Authors: GREEN, CAROLINE - University Of Missouri; JAWORSKI, ALEAH - University Of Missouri; MANGIAVACCHI, PAULA - University Of Missouri; SPATE, LEE - University Of Missouri; Walker, Lianna; PRATHER, RANDALL - University Of Missouri; LEE, KIHO - University Of Missouri; Redel, Bethany

Submitted to: Molecular Reproduction and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2025
Publication Date: 1/14/2026
Citation: Green, C.L., Jaworski, A., Mangiavacchi, P.M., Spate, L., Walker, L.R., Prather, R.S., Lee, K., Redel, B.K. 2026. Transcriptional profiling of cumulus cells from FLI-matured porcine oocytes identifies junctional genes as key components in oocyte maturation. Molecular Reproduction and Development. 93(1). https://doi.org/10.1002/mrd.70080Digital Object Identifier (DOI).
DOI: https://doi.org/10.1002/mrd.70080Digital Object Identifier (DOI)

Interpretive Summary: Scientists are working to improve the way pig eggs, called oocytes, are matured and developed in the lab. This process is important for protecting valuable genetic traits in pigs and for use in medicine and agriculture. However, growing pig eggs and embryos outside the body is challenging. Recently, a special additive called FLI has shown great promise in improving this process. Scientists are still trying to understand how FLI improves oocyte development. To explore this further here, researchers studied the cells that surround the egg, called cumulus cells, which help the egg develop. FLI changed the gene expression in these cells and many of these genes were involved in cell communication. Further experiments confirmed that FLI improved protein expression of some of these key communication genes and may be the reason why FLI is improving oocyte development in the lab. This study helps scientists understand how to improve oocyte development, ultimately leading to healthier embryos and more piglets.

Technical Abstract: In vitro oocyte maturation and embryo culture are critical for preserving and expanding genetic lines, and necessary to produce genetically engineered pigs for biomedical and agricultural purposes. However, suboptimal in vitro conditions compromise oocyte and embryo viability. Recent improvements to in vitro maturation medium, including the addition of FGF2, LIF, and IGF1 (FLI), have increased the number of oocytes that reached the metaphase II stage, doubled the number of oocytes that reached the blastocyst stage, and quadrupled the number of piglets born after embryo transfer. Despite these benefits, the underlying cellular mechanisms remain not fully understood. Given the essential role of cumulus cells (CCs) in oocyte maturation, we investigated how FLI affects CCs gene expression. Cumulus-oocyte complexes were matured for 24 h in control or FLI media, and CCs from oocytes that reached the blastocyst stage underwent RNA sequencing. FLI altered 1257 transcripts (423 upregulated, 834 downregulated; adj-p < 0.05), with enrichment of junctional communication genes and downregulation of extracellular matrix organization. Immunofluorescence confirmed increased TJP1, TJP2, and GJA4 in FLI-treated complexes. Additionally, cortical granule localization suggested enhanced cytoplasmic maturation with FLI supplementation. These findings indicate that FLI promotes CC communication and supports improved oocyte competence in porcine in vitro maturation.