Probing Proteoform Heterogeneity From Single Human Oocytes

Area of Science:

• Reproductive Biology
• Proteomics
• Cellular Biology

Background:

• Ovarian tissue cryopreservation (OTC) offers fertility preservation for young patients facing gonadotoxic treatments.
• While ovarian tissue transplantation (OTT) can restore fertility, risks of malignant cell reintroduction limit options for some.
• Improving in vitro maturation (IVM) of immature oocytes is critical for expanding fertility restoration, especially for prepubertal patients.

Purpose of the Study:

• To characterize intact proteoforms in single human oocytes across the pubertal transition.
• To identify age-related changes in the oocyte proteome.
• To establish a foundation for enhancing IVM efficiency and fertility restoration accessibility.

Main Methods:

• Single-cell proteoform imaging mass spectrometry (scPiMS) was employed to analyze intact proteoforms in human oocytes.
• Proteomic analysis was performed on oocytes from ovarian tissue cryopreservation (OTC) donors aged 2-33 years.
• scPiMS was used to differentiate proteoforms in oocytes versus cumulus granulosa cells within cumulus oocyte complexes (COCs).

Main Results:

• Identified 559 proteins and 769 unique proteoforms across 28 oocytes, averaging 78 proteoforms per oocyte.
• Characterized proteoform landscapes for the subcortical maternal complex (SCMC) components KHDC3 and OOEP.
• Discovered novel proteoforms in KHDC3 and OOEP that vary with donor age, highlighting pubertal changes.

Conclusions:

• This study provides the first comprehensive proteomic characterization of human oocytes across puberty.
• Understanding age-specific proteoform changes is essential for optimizing IVM protocols.
• These findings lay the groundwork for improving fertility restoration outcomes for a broader patient population.