Lia Finnegan
Research Mentor(s): Saher Hammoud
Mentor Department: Human Genetics
Authors: Saher S Hammoud, Ritvija Agrawal, Lindsay Mortiz, Sue Hammoud, Lia Finnegan
Session: Session 7 (4:00pm – 4: 50pm)
Presentation Type: Oral
Abstract
During spermatogenesis, spermatids undergo extensive chromatin remodeling, replacing most histones with protamines. In all mammals, DNA condensation in sperm relies on Protamine-1 (PRM1), while humans, primates, and mice also express Protamine-2 (PRM2). Maintaining the correct PRM1-to-PRM2 ratio is essential for fertility, as imbalances or loss of either protamine are linked to infertility.Despite the evolutionary conservation of sperm chromatin packaging for over 500 million years, protamine sequences evolve rapidly across species. However, it is unclear whether these variations affect DNA binding and chromatin structure. To address this, my project examines whether protamine sequence differences influence sperm chromatin packaging. For this, the lab generated transgenic mouse lines with specific amino acid changes in PRM1. We then 1) Isolated protamines from wild-type and mutant mice using acid extraction, 2) Purified PRM1 and PRM2 using gel filtration chromatography, 3) Confirmed purity of the protein through immunoblotting. We next aim to test the DNA-binding affinity of the purified PRM1 using electrophoretic mobility shift assays (EMSAs). Overall, my project aims to reveal how protamine sequence variations shape sperm chromatin structure, providing new insights into fertility and evolution.
