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Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
kinase, TSSK1, human, sperm, post-translational modification, CASA
The ability of a sperm to fertilize an egg involves a complex series of events, referred to as capacitation. Capacitation involves sperm acquiring a hyperactive state of motility and the ability to undergo an exocytotic process called the acrosome reaction (AR). Molecular intervention of cell signaling pathways involved in sperm capacitation has been proposed as a way for developing novel male contraceptives.
Testis-specific serine kinase1 (TSSK1) is a novel protein in the calcium/calmodulin superfamily of human kinases, and has the potential for targeted inhibition to provide a highly safe and effective form of male contraception. It is expressed post-meiotically during spermatogenesis, and is localized to the head and tail of the mature sperm. Tssk1/Tssk2 knockout (KO) mouse models have demonstrated that these proteins are necessary for sperm function as deletion of these genes have rendered male mice infertile. Studies presented here involve the investigation of the biochemical regulation of TSSK1 and its role in human sperm capacitation.
Posttranslational modification of TSSK1 was analyzed in capacitated human sperm in the presence or absence of AR inducers in vitro. Furthermore, experimental conditions were tested for measuring TSSK1 enzymatic activity in capacitated human sperm, and TSSK1 kinase activity was further correlated to the observed phosphorylation/dephosphorylation.
Lastly, a computer-aided sperm analysis (CASA) protocol for assessing human sperm motility was standardized. Human sperm cell subpopulations were evaluated under different sperm capacitating conditions, and a Boolean argument was created to quantify progressive and non-progressive hyperactive cells. Determining TSSK1’s regulation by posttranslational modifications will help further characterize this protein as a potential target for inhibition and, ultimately, for use as a novel technique of male contraception. Improved conditions for human sperm analysis by CASA may provide a tool for assessing a potential role of TSSK1 in human sperm motility and hyperactivation.
Ana Maria Salicioni