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Updated: May 1, 2026
Phosphopeptide Analysis of Rodent Epididymal Spermatozoa
Published on: December 30, 2014
Expression and localization of prolyl oligopeptidase in mouse testis and its possible involvement in sperm motility
Atsushi Kimura1, Hitoshi Matsui, Takayuki Takahashi
1Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo, 060-0810, Japan.
Abstract:
Prolyl oligopeptidase (POP) expression in mouse testis during sexual maturation was examined. Northern blot analysis showed that POP mRNA expression was highest at 2 weeks of age, and gradually reduced thereafter. However, enzyme activity was almost constant during the examined period. In situ hybridization study revealed a change in the expression site of POP mRNA in testis during sexual maturation. Positive signals were detected in all types of cells in the seminiferous tubules before maturation, and were restricted to spermatids at the spermatogenesis cycle stages I-VIII in adult mice. POP was detected in the insoluble fraction of sperm by Western blot analysis. Immunohistochemical analyses showed that POP is localized in the spermatids at steps 12-16 of spermiogenesis and in the midpiece of the sperm fragellum. It was also found that specific POP inhibitors, poststatin and benzyloxycarbonyl-proline-prolinal, suppressed sperm motility. These results suggest that POP may be involved in meiosis of spermatocytes, differentiation of spermatids, and sperm motility in the mouse.
Insights
Prolyl oligopeptidase (POP) expression changes during mouse sexual maturation, with its mRNA levels decreasing while enzyme activity remains constant. This enzyme is crucial for sperm function and motility.
Area of Science:
- Reproductive biology
- Enzymology
- Molecular biology
Background:
- Prolyl oligopeptidase (POP) is an enzyme with known roles in various physiological processes.
- Its specific function and expression patterns during male reproductive development in mice are not fully understood.
Purpose of the Study:
- To investigate the expression and localization of Prolyl oligopeptidase (POP) in the mouse testis during sexual maturation.
- To explore the potential role of POP in spermatogenesis and sperm function.
Main Methods:
- Northern blot analysis to assess POP mRNA expression levels.
- In situ hybridization to determine the spatial and temporal expression sites of POP mRNA.
- Western blot analysis to detect POP protein in sperm fractions.
- Immunohistochemical analyses to pinpoint POP localization within sperm.
- Functional assays using POP inhibitors to assess effects on sperm motility.
Main Results:
- POP mRNA expression peaked at 2 weeks of age and declined thereafter, while enzyme activity remained stable.
- POP mRNA expression sites shifted from all seminiferous tubule cells to restricted spermatids (stages I-VIII) in adult mice.
- POP protein was localized in spermatids (steps 12-16) and the midpiece of sperm flagella.
- POP inhibitors significantly reduced sperm motility.
Conclusions:
- Prolyl oligopeptidase (POP) expression and localization change dynamically during mouse sexual maturation.
- POP is implicated in key stages of spermatogenesis, including meiosis and spermatid differentiation.
- POP plays a significant role in regulating sperm motility.
