(146) Dysregulation of Alternative Splicing Patterns in the Ovaries of Reproductively Aged Mice

1 Department of Biomedical and Translational Sciences, Eastern Virginia Medical School, Norfolk, VA, USA

2 Advanced Sequencing Program, Eastern Virginia Medical School, Norfolk, VA, USA

† These authors contributed equally to this work



Abstract Text:

Female fertility wanes long before other somatic functions, yet the RNA‐level mechanisms that accompany ovarian aging remain obscure. We profiled full-length native transcripts in ovaries of reproductively young (6 week) and aged (14 months) C57BL/6 mice 46 hours after follicle-growth (PMSG) or ovulatory (PMSG + hCG) stimulation using Oxford Nanopore direct RNA sequencing. From ~4.4 million reads we detected 56,862 unique transcripts, 72.7 % of which lacked an Ensembl annotation, underscoring extensive isoform novelty. A Bayesian beta-binomial model applied to promoter-grouped isoform fractions uncovered 1,086 age-biased splicing events after PMSG and 3,222 after PMSG + hCG. Aging preferentially increased intron retention and shifted splice-site choice toward proximal alternative first exons and distal alternative last exons, yielding longer transcripts with remodeled termini. Over one-third of age-sensitive events altered open-reading frames; 983 introduced premature stop codons, most commonly via alternative last exon usage. Protein-domain analysis revealed enrichment of disrupted NADH-oxidoreductase, cytochrome P450 and 3β-hydroxysteroid-dehydrogenase motifs, implicating compromised mitochondrial respiration and steroidogenesis in aged ovaries. Collectively, our data show that reproductive aging remodels promoter selection and splice-site choice to diversify the ovarian transcriptome and generate isoforms predicted to impair metabolic and endocrine functions. Targeting splice regulators or age-specific isoforms may provide new strategies to preserve ovarian health and prolong reproductive lifespan.