To perform a comprehensive assessment of protamine isoforms and modifications in human sperm with the aim of identifying how protamine modifications/isoforms are altered in men with reduced sperm motility and low sperm count.
Cross-sectional SETTING: Academic medical center.
18 men with prior reported pregnancy and normozoospermia (normal sperm), 14 men from couples with infertility and asthenozoospermia (reduced sperm motility), and 24 men from couples with infertility and oligoasthenoteratozoospermia (low sperm count and motility and abnormal sperm morphology).
Proteomic assessment using both Top-down and Bottom-up Liquid-chromatography Mass-Spectrometry (LC-MS) analysis.
13 post-translational modifications were identified on protamine 1 and 2 utilizing bottom-up MS including both phosphorylation and methylation. Top-down MS revealed an unmodified and phosphorylated isoform of protamine 1 and the 3 major isoforms of protamine 2 HP2, HP3, and HP4. Protamine 1 phosphorylation was overall higher in men with male-factor infertility compared to those with normal semen analysis (40.5% vs 32.6 vs p=0.012). There was no difference in protamine post-translational modifications or isoforms of protamine 2 from men with normal vs abnormal fertility.
Human protamines bear a number of post-translational modifications, with alterations in protamine 1 phosphorylation noted in the setting of male-factor infertility.
F&S science. 2023 Dec 06 [Epub ahead of print]
Samantha B Schon, Lindsay Moritz, Mashiat Rabbani, Julia Meguid, Brock R Juliano, Brandon T Ruotolo, Kenneth Aston, Saher Sue Hammoud
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI. Electronic address: ., Department of Human Genetics, University of Michigan, Ann Arbor, MI., Department of Chemistry, University of Michigan, Ann Arbor, MI., Department of Surgery, University of Utah, Salt Lake City, UT., Department of Human Genetics, University of Michigan, Ann Arbor, MI; Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI; Department of Urology, University of Michigan, Ann Arbor, MI.