The central goal of this project is to identify and characterize small molecule inhibitors of Ubiquitin specific peptidase 51 (USP51), a deubiquitinating (DUB) enzyme exclusive to sperm, as a means to develop a reversible, non-hormonal male contraceptive. The ubiquitin system is fundamental to ensure protein turnover within mammalian cells. Ubiquitin-activating enzymes, ubiquitin-conjugating enzymes, and ubiquitin protein ligases catalyze the attachment of ubiquitin molecules to proteins, a process that targets them to the proteasome for degradation. DUBs catalyze the removal of ubiquitin to facilitate their recycling. We have identified USP51 to be specifically expressed in late elongating spermatids and epididymal sperm. USP51 depletion in mice using Vivo-Morpholinos results in male infertility due to a complete block of sperm motility. Our overall hypothesis is tat USP51 is a viable contraceptive target and that small molecules existing in nature or modified in the laboratory will effectively and reversibly inhibit USP51 function in epididymal sperm. We will pursue the following Specific Aims to address this hypothesis: 1) Validate the targeting of USP51 as an effective strategy for contraceptive development. 2) Screen small molecule libraries in silico and in vitro to identify hit compounds. 3) Perform hit-to-lead medicinal chemistry optimization and assess the exposure of sperm, testes and animals to candidates for efficacy and reversibility. These studies will advance our basic understanding of spermatogenesis and sperm function, as well as provide the potential for developing new contraceptive agents that reversibly inhibit a critical sperm enzyme.

Public Health Relevance

Nearly 40% of pregnancies in the U.S. are unintended - a rate that has held steady for the past 30 years. Globally, overpopulation continues to burden specific countries and regions. While both hormonal and nonhormonal contraceptives are available to women, contraceptive options for men are currently limited to condoms and vasectomies. The goal of this research project is to identify and characterize small molecules that target sperm deubiquitinating enzymes as a means to develop a reversible, safe, effective, nonhormonal male-specific contraceptive agent.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project--Cooperative Agreements (U01)
Project #
5R01HD084046-03
Application #
9253031
Study Section
Special Emphasis Panel (ZHD1-DSR-L (50))
Program Officer
Kaufman, Steven
Project Start
2015-05-01
Project End
2020-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
3
Fiscal Year
2017
Total Cost
$204,394
Indirect Cost
$56,704
Name
Children's Memorial Hospital (Chicago)
Department
Type
Independent Hospitals
DUNS #
074438755
City
Chicago
State
IL
Country
United States
Zip Code
60611