Single-cell multiomic analysis reveals methylome and transcriptome deviations following oocyte maturation in vitro

Area of Science:

• Reproductive Biology
• Epigenetics
• Genomics

Background:

• In vitro maturation (IVM) is crucial for assisted reproduction but often results in lower embryo development rates than in vivo maturation.
• Concerns persist regarding the impact of IVM on oocyte quality and developmental potential.

Purpose of the Study:

• To investigate the effects of IVM on the methylome and transcriptome of bovine oocytes and their corresponding cumulus cells.
• To compare genomic profiles of oocytes matured in vitro versus in vivo from the same animal.

Main Methods:

• Single-cell methylome and transcriptome sequencing of bovine oocytes.
• Transcriptome analysis of associated cumulus cells.
• Comparison of genomic data between in vitro and in vivo matured oocytes.

Main Results:

• In vitro maturation significantly altered both the oocyte methylome and transcriptome.
• Decreased DNA methylation was observed in CpG islands of imprinted genes, including MEST, NNAT, and MIMT1, which are linked to large offspring syndrome.
• Cumulus cell transcriptomes showed impaired mitochondrial function, hypoxia responses, and cell adhesion following in vitro maturation.

Conclusions:

• The maturation environment profoundly influences epigenetic regulators and mRNA profiles in oocytes.
• IVM-induced epigenetic alterations may negatively impact oocyte quality and developmental competence.
• Findings offer insights for optimizing IVM protocols in assisted reproductive technologies.