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Updated: Sep 20, 2026
Analysis of Epididymal Protein Synthesis and Secretion
Published on: August 25, 2018
SPAM1 (PH-20) protein and mRNA expression in the epididymides of humans and macaques: utilizing laser
Eric A Evans1, Hong Zhang, Patricia A Martin-DeLeon
1Department of Biological Sciences, University of Delaware, Newark, Delaware, USA. eric.evans@stanford.edu
Background:
The Sperm Adhesion Molecule 1 (SPAM1) is an important sperm surface hyaluronidase with at least three functions in mammalian fertilization. Previously our laboratory reported that in the mouse, in addition to its expression in the testis, Spam1 is synthesized in the epididymis where it is found in membranous vesicles in the principal cells of the epithelium in all three regions. Since SPAM1 is widely conserved among mammals the aim of the study was to determine if its expression pattern in the epididymis is conserved in rodents and primates.
Methods:
We used laser microdissection (LM)/RT-PCR on frozen and paraffin-embedded epididymal sections of humans (n = 3) and macaques (n = 2) as well as in situ transcript hybridization to determine if transcripts are present in the epididymal epithelium. Western analysis and immunohistochemistry were used to detect and confirm the protein expression, and hyaluronic acid substrate gel electrophoresis analyzed its hyaluronidase activity. An in silico analysis of the proximal promoter of SPAM1 was also performed to identify relevant putative transcription binding sites for the androgen receptor.
Results:
We demonstrate that mRNA unique to SPAM1 is present in the principal cells of the epididymal epithelium in all individuals of both species studied. SPAM1 protein is present in all three regions of the epididymis, as well as the vas deferens, and is localized similarly to the transcripts. SPAM1 was shown to have hyaluronidase activity at pH 7.0. In the proximal promoter of SPAM1 were uncovered putative epididymal transcription factor binding sites including androgen receptor elements (AREs), consistent with epididymal expression.
Conclusions:
These findings allow us to conclude that epididymal SPAM1 is conserved in at least two mammalian classes, rodents and primates. This conservation of expression suggests that the protein is likely to play an important function, possibly in sperm maturation.
Insights
Sperm Adhesion Molecule 1 (SPAM1) is expressed in the epididymis of humans and macaques, similar to rodents. This conserved expression suggests SPAM1 plays a vital role in sperm maturation.
Area of Science:
- Reproductive Biology
- Molecular Biology
- Mammalian Fertilization
Background:
- Sperm Adhesion Molecule 1 (SPAM1) is a crucial sperm surface hyaluronidase involved in mammalian fertilization.
- Previous studies identified SPAM1 expression in the mouse epididymis, localized to membranous vesicles in principal cells.
- SPAM1 is conserved across mammals, prompting an investigation into its epididymal expression patterns in primates and rodents.
Purpose of the Study:
- To investigate the conservation of Sperm Adhesion Molecule 1 (SPAM1) expression in the epididymis of primates and rodents.
- To determine the localization and functional activity of epididymal SPAM1.
- To explore potential regulatory mechanisms of SPAM1 expression in the epididymis.
Main Methods:
- Laser microdissection (LM)/RT-PCR and in situ hybridization were used to detect SPAM1 transcripts in human and macaque epididymal sections.
- Western analysis and immunohistochemistry confirmed SPAM1 protein expression and localization.
- Hyaluronic acid substrate gel electrophoresis assessed SPAM1 hyaluronidase activity, and in silico analysis identified potential androgen receptor binding sites in the SPAM1 promoter.
Main Results:
- SPAM1 mRNA was detected in the principal cells of the epididymal epithelium in all human and macaque individuals studied.
- SPAM1 protein was found throughout the epididymis and vas deferens, with localization consistent with transcript distribution.
- SPAM1 exhibited hyaluronidase activity at pH 7.0, and its promoter contains putative androgen receptor elements.
Conclusions:
- Epididymal SPAM1 expression is conserved across rodents and primates, indicating its importance in mammalian reproduction.
- The presence of androgen receptor elements suggests hormonal regulation of SPAM1 in the epididymis.
- Conserved epididymal SPAM1 expression likely signifies a critical role in sperm maturation.
