Dissecting the roles of EPPIN/SVS2 binding in the modulation of mouse sperm motility.

• Grant number: 23/00125-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2023
• End date: December 31, 2023
• Field of knowledge: Biological Sciences - Pharmacology - Biochemical and Molecular Pharmacology
• Principal Investigator: Erick José Ramo da Silva
• Grantee: Ana Clara Ferrari Themer
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Associated research grant: 21/06718-7 - Translational studies on the sperm-binding protein EPPIN as a male contraceptive drug target, AP.JP2

Abstract

In mammals, proteins belonging to the REST (rapidly-evolving seminal vesicle transcribed) family, secreted by the seminal vesicles, are the most abundant components of the seminal plasma. In humans, the major REST protein is semenogelin-1 (SEMG1), which binds EPPIN on the surface of ejaculated spermatozoa, leading to inhibition of sperm motility that lasts until SEMG1 is cleaved by prostate-specific antigen (PSA). Studies demonstrated that SEMG1 sequences flanking its unique cysteine residue are critical for both EPPIN binding and inhibition of sperm motility. In mice, seminal-vesicle secretory protein 2 (SVS2), the major REST protein and ortholog to SEMG1, plays a similar role as a native regulator of sperm motility. Consistently with the hypothesis that both SEMG1 and SVS2 are functionally conserved as seminal plasma inhibitory factors of sperm function, we recently showed that SVS2 is an EPPIN-binding partner in mouse spermatozoa. Seeking to test this hypothesis further, we propose to investigate whether binding to EPPIN is required for the effects of SVS2 on mouse sperm motility. We will perform Computer-Assisted Sperm Analysis (CASA) to evaluate the effects of different recombinant SVS2 isoforms (full-length and truncations containing or not the EPPIN-binding sequence) on mouse sperm motility parameters in concentration-response studies. We will evaluate the following outcomes: (i) percentage of sperm motility (%motile, %progressive, %hyperactive, and %static); and (ii) sperm kinematics parameters governing progressive and vigorous movements. We hope to broaden our understanding of the relevance of interactions between EPPIN and REST proteins for sperm function, which may foster novel therapeutic strategies for male infertility and male contraception.