Page 16 - HKSEMR2020 Programme book

Oral Presentation (Basic Science) Abstracts

Identification of spermatozoa-interacting proteins on human

oviductal epithelial cells

Xinyi Tian, Cheuk-Lun Lee, Philip C.N. Chiu
Department of Obstetrics and Gynecology, The University of Hong Kong, Pokfulam Road, Hong Kong SAR.

Introduction / Background / Objectives: Results / Outcomes:
In many mammalian species, including humans, the oviduct We established a novel 3D assay for studying spermatozoa-OEC
functions as a sperm reservoir created by the binding of the interaction in humans. The assay was established on the binding of
sperm to the oviductal epithelial cells (OECs). This interaction is sperm to the spheroid of an immortalized human OEC line, OE-E6/
a species-specific event that involves the recognition of defined E7. We found that OE-E6/E7 cell spheroid-bound spermatozoa had
carbohydrates on the OEC by the sperm. When ovulation is a significantly (P < 0.05) lower DNA fragmentation level than the
imminent, these stored sperm are released from the reservoir unbound group. Using an affinity chromatography technique with
to move to the fertilization site. Sperm reservoir formation in the sFUT5 as a bait, two potential sFUT5-binding proteins on OECs
oviduct serves to maintain the fertilizing capacity of spermatozoa were identified by mass spectrometry: cell adhesion molecule
until ovulation. Adhesion to the oviduct also plays a key role in 4 (CADM4) and CD44. Both CADM4 and CD44 were capable of
the selection of sperm with normal chromatin structure and binding to the human spermatozoa. Interestingly, their binding is
superior fertilization ability. Most of our knowledge on the roles not universal, with weak or no detectable binding in many human
of the sperm reservoir in fertilization comes from studies in other spermatozoa, implying that OECs might selectively bind to a
mammalian species. The functions and mechanism of sperm sperm subpopulation with superior fertilization ability. However,
reservoir formation in human is still unknown. Our previous no inhibitory effects of CADM4/CD44 on sperm functions were
study demonstrated that sperm fucosyltransferase-5 (sFUT5), a observed.
carbohydrate-binding protein on spermatozoa, is responsible for
spermatozoa-OEC interaction in humans.
Conclusion:

OEC-bound sperm had higher DNA integrity compared to unbound
Methods:
sperm. CADM4/CD44 mediated spermatozoa-OEC binding by
Spermatozoa were obtained from semen samples from interacting with sFUT5 on the spermatozoa. The results of this
normozoospermic men. Affinity chromatography followed by mass project enhance our understanding of the physiological role of
spectrometric analysis was used to identify the sFUT5-binding the human oviduct on sperm functions. They also give clues to
proteins on OECs. The expression of sFUT5-binding proteins guide future studies on the potential clinical application of sFUT5
was studied by immunostaining or flow cytometric analysis. binding protein on OECs as a natural molecule for functional sperm
Their functional roles in sperm were determined using functional selection.
blocking antibodies. Sperm functions were assessed by standard
assays.

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