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Identification and characterization of P31m, a novel sperm protein in Cynomolgus monkey (Macaca fascicularis)
N Lamontagne1, C Légaré, C Gaudreault
1Centre de Recherche en Biologie de la Reproduction and Département d'Obstétrique-Gynécologie, Faculté de Médecine, Université Laval, 2705 Blvd. Laurier, Ste-Foy, Quebec, Canada G1V 4G2.
Abstract:
We have previously described a hamster sperm glycoprotein, P26h, which is implicated in the cascade of events occurring during the interaction between mature spermatozoa and the oocyte's zona pellucida. The P26h is acquired on the acrosomal cap of the spermatozoon during its maturation arising within the epididymis. Lately, using a polyclonal antiserum raised against P26h, a 34 kDa protein, P34H, has been identified on the acrosomal cap of the human spermatozoon. The cloning and sequencing of the cDNA encoding P34H has revealed a 65% similarity between the P34H and P26h amino acid sequences. Considering that P26h shows total immunocontraceptive properties in the hamster, it is of relevant importance to have an animal model phylogenetically closer to the human. Using the Cynomolgus monkey, we searched for a protein autologous to the human P34H. A 31 kDa protein, the P31m, localized on the acrosomal cap of the monkey spermatozoon has been identified by a Western blot analysis and by immunohistochemical techniques using an anti-hamster P26h antiserum. Northern blot analysis showed increasing high levels of the P31m mRNA through the epididymis and at lower levels in the testis. In situ hybridization showed the presence of the P31m mRNA in the principal cells of the epididymis. The cloning and sequencing of the cDNA encoding the P31m showed a high homology of 97% identity between the P31m and P34H nucleotidic sequences. This study clearly demonstrates that the monkey P31m is the homologous protein of the hamster P26h and of the human P34H. Mol. Reprod. Dev. 59: 431-441, 2001.
Insights
Researchers identified a monkey sperm protein, P31m, homologous to human P34H and hamster P26h. This finding is crucial for developing new contraceptives using a closer animal model for human reproductive studies.
Area of Science:
- Reproductive Biology
- Molecular Endocrinology
- Sperm-Oocyte Interactions
Background:
- The hamster sperm glycoprotein P26h is involved in sperm-zona pellucida interaction and exhibits immunocontraceptive properties.
- A human homolog, P34H, shares 65% amino acid similarity with P26h, suggesting a conserved function.
Purpose of the Study:
- To identify a homologous protein to human P34H in a phylogenetically closer animal model, the Cynomolgus monkey.
- To investigate the expression and localization of this homologous protein in monkey sperm.
Main Methods:
- Western blot and immunohistochemical analysis using anti-P26h antiserum.
- Northern blot and in situ hybridization to analyze mRNA expression and localization.
- cDNA cloning and sequencing to determine nucleotide sequence homology.
Main Results:
- A 31 kDa protein, P31m, was identified on the acrosomal cap of Cynomolgus monkey spermatozoa.
- P31m mRNA levels increase during epididymal maturation and are present in epididymal principal cells.
- Nucleotide sequences of P31m and P34H show 97% identity, confirming high homology.
Conclusions:
- The monkey P31m is the functional homolog of hamster P26h and human P34H.
- This study establishes the Cynomolgus monkey as a relevant model for studying human sperm-zona pellucida interactions and for contraceptive development.