Single-nucleus and spatial transcriptomics of human pediatric ovary: Molecular insights into the dysregulated signaling pathways underlying premature ovarian insufficiency in classic galactosemia

Authors

• R Kavarthapu
• H Lou
• T Badger
• R Balasubramanian
• V Huyhn
• M De La Luz Sierra
• JC Yano
• V Gomez-Lobo

Abstract

Classic galactosemia (CG) is an inborn error of galactose metabolism caused by mutations in the GALT gene. Premature ovarian insufficiency (POI) is a later complication that affects 80% of women with CG due to decline in ovarian reserve. Here, we used single-nucleus RNA-sequencing (snRNA-seq) and spatial transcriptomics techniques to elucidate the mechanism underlying early onset of POI in pre-pubertal girls diagnosed with CG. SnRNA-seq profiling of the human pediatric ovary revealed a diverse ovarian microenvironment with seven major cell types. Our transcriptomic analysis revealed an increase in the expression of several endoplasmic reticulum stress and oxidative stress associated genes, which can promote apoptosis of granulosa cells in the CG group. PTEN/PI3K/AKT signaling, crucial for primordial follicle activation and survival was dysregulated as supported by upregulated PTEN transcripts and marked reduction in phospho-AKT. We also found a significant increase in CASP9 protein expression in the primordial follicles suggesting accelerated follicle atresia in the CG patients. Furthermore, we identified four different subpopulations of stromal cells with distinct transcriptomic signatures. We found the extracellular matrix, integrin, and gap junction signaling pathways, essential for structural support of the ovarian stroma were profoundly altered in CG patients. Our findings provide molecular insights into the dysregulated cellular pathways that can explain the etiology of POI in CG patients, which have implications in the development of therapeutic interventions to preserve ovarian function and promote reproductive health.

Scientific Focus Area: Clinical Research

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