Disruption of protein phosphatase 1 complexes with the use of bioportides as a novel approach to target sperm motility

Objective: To design protein phosphatase 1 (PP1)-disrupting peptides covalently coupled to inert cell-penetrating peptides (CPPs) as sychnologically organized bioportide constructs as a strategy to modulate sperm motility. Design: Experimental study. Setting: Academic research laboratory. Patient(s)/Animal(s): Normozoospermic men providing samples for routine analysis and Holstein Frisian bulls. Intervention(s): None. Main Outcome Measure(s): Effect of the bioportides on the activity and interactions of PP1 gamma 2-a PP1 isoform expressed exclusively in testicular germ cells and sperm-and on sperm vitality and motility. Result(s): PP1-disrupting peptides were designed based on the sequences from: 1) a sperm-specific PP1 interactor (A kinase anchor protein 4); and 2) a PP1 inhibitor (protein phosphatase inhibitor 2). Those sequences were covalently coupled to inert CPPs as bioportide constructs, which were successfully delivered to the flagellum of sperm cells to induce a marked impact on PP1 gamma 2 activity and sperm motility. Molecular modeling studies further facilitated the identification of an optimized PP1-binding sequence and enabled the development of a modified stop-sperm bioportide with reduced size and increased potency of action. In addition, a bioportide mimetic of the unique 22-amino acid C-terminus of PP1 gamma 2 accumulated within spermatozoa to significantly reduce sperm motility and further define the PP1 gamma 2-specific interactome. Conclusion(s): These investigations demonstrate the utility of CPPs to deliver peptide sequences that target unique protein-protein interactions in spermatozoa to achieve a significant impact upon spermatozoa motility, a key prognostic indicator of male fertility. (C) 2020 by American Society for Reproductive Medicine.

Automated summary

By designing bioportides with targeting PP1 disrupting function, the sperm vitality and motility were significantly affected, providing a new research approach for predicting male fertility indicators.