Human Epididymis Protein 4 Quantification and Interaction Network Analysis in Seminal Plasma

Area of Science:

• Reproductive Biology
• Proteomics
• Biochemistry

Background:

• Human Epididymis protein 4 (HE4), a whey acidic four-disulfide core protein, is known as an ovarian cancer marker.
• HE4, purified from human seminal plasma, acts as a protease inhibitor, potentially protecting spermatozoa.
• The precise biological function of HE4 in reproductive physiology remains largely unelucidated.

Purpose of the Study:

• To investigate the potential roles of HE4 in reproductive physiology.
• To identify the HE4 interactome within human seminal plasma.

Main Methods:

• Co-immunoprecipitation and MALDI-TOF/MS were employed to identify HE4 binding proteins.
• Enzyme-linked immunosorbent assay (ELISA) was used to quantify HE4 levels in seminal plasma.

Main Results:

• Ten HE4 binding proteins were identified, including protein phosphatase 1 regulatory subunit 21 and prostatic acid phosphatase.
• The identified protein network suggests HE4 involvement in sperm capacitation, motility, and maturation.
• Elevated HE4 concentrations were observed in normozoospermic samples compared to azoospermic and asthenozoospermic samples.

Conclusions:

• The identified HE4 interactome supports its critical role in male fertility.
• HE4 is implicated in essential processes of sperm maturation, motility, and capacitation.