# Targeting testis-specific ubiquitin-proteasome pathways for male contraception

> **NIH NIH R61** · BAYLOR COLLEGE OF MEDICINE · 2020 · $400,000

## Abstract

PROJECT SUMMARY
Ubiquitination is a post-translational modification of proteins that is required for many cellular processes,
including protein degradation by the proteasome, and requires the sequential action of three enzymes called
E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin-ligase). While there is a
single E1 enzyme and ~40 E2 enzymes, there are over 600 E3 enzymes in humans, with the RING (Really
Interesting Novel Gene) family of E3 ubiquitin ligases being the most abundant. The RING E3 ubiquitin ligases
recognize specific substrate proteins and interact with the ubiquitin-charged E2 enzymes to transfer the
ubiquitin to the substrate. Recently, this pathway has been utilized to target physiologically relevant proteins for
degradation using proteolysis-targeting chimeric (PROTAC) small molecules that bind to both an E3 ubiquitin
ligase and a target protein. In the R61 component of this NIH grant proposal, we have chosen to validate the
fertility essential functions of four evolutionarily-conserved testis-enriched ubiquitin-proteasome pathway
proteins using a CRISPR/Cas9 knockout mouse strategy. Using CRISPR/Cas9, we have created mutations in
all four of these genes, and preliminary data has revealed that at least one of these genes is required for male
fertility. Our next step is to identify small molecules that bind these proteins using DNA-Encoded Chemistry
Technology (DEC-Tec), in which each protein will be screened in vitro against our over 2.8 BILLION molecule
collection. DEC-Tec is an economical process to rapidly uncover lead molecules, which will be tested directly
for their inhibitory action or linked with other contraceptives to form PROTACs for targeted degradation of other
spermatogenic-specific contraceptive targets. In the R33 component of this NIH grant proposal, we will use
medicinal chemistry to optimize inhibitors for direct contraceptive action and create PROTACS that bind these
E3 ubiquitin protein ligases and known contraceptives. Our R61/R33 proposal is an innovative, discovery-
based, and integrated strategy to use mouse genetics to define the essential roles of these four testis-enriched
ubiquitination-proteasome pathway proteins, to use DEC-Tec to rapidly identify small molecule binders, and to
directly use these small molecules as non-hormonal contraceptives or to link them to other lead contraceptive
compounds (as PROTACs) to direct the contraceptive target for degradation.

## Key facts

- **NIH application ID:** 10018522
- **Project number:** 5R61HD099722-02
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** MARTIN M. MATZUK
- **Activity code:** R61 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $400,000
- **Award type:** 5
- **Project period:** 2019-09-13 → 2022-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10018522

## Citation

> US National Institutes of Health, RePORTER application 10018522, Targeting testis-specific ubiquitin-proteasome pathways for male contraception (5R61HD099722-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10018522. Licensed CC0.

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