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Synthesis, characterization and hormonal regulation of epididymal proteins during postnatal development of the mouse
1Laboratoire de Biologie Cellulaire, Université René Descartes, Paris, France.
Abstract:
Maturation of mammalian spermatozoa depends on their interactions with epididymal proteins. The incorporation of 35S-methionine into these proteins was investigated by in vitro incubation of tissue minces from the mouse epididymis at different ages of postnatal development. The greatest amount of incorporation per wet weight of tissue was seen in 7 to 21-day-old mice. It decreased progressively during development while the rate of proteins released into the medium remained almost constant until the adult state. Separation of labeled proteins on sodium dodecyl sulphate polyacrylamide gels followed by fluorography showed that the great majority of secretory proteins synthesized in adult mouse epididymis could be recovered already from 7-day-old animals. Regional differences appeared at 21 days of age. These were marked by the secretion of proteins characteristic of the proximal (26, 25, 20, 19 kDa) and distal (44, 29 kDa) epididymis. Analysis of cytosol and luminal fluid proteins from prepubertal and adult epididymis revealed a number of proteins of the same mobility as those synthesized and secreted in vitro. Among the luminal proteins which showed variations during development and regional differences, four (29, 26, 20, 19 kDa) were characteristics of the epididymis and three (88, 34, 13 kDa) comigrated with testicular components. Castration or estrogen treatment of prepubertal mice for 4, 3 and 2 weeks inhibited or reduced the synthesis of the luminal proteins which appeared during postnatal development and/or presented regional differences. Testosterone replacement of castrated mice reversed this effect and induced the secretion of new proteins (37, 24 kDa).(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Sperm maturation relies on epididymal proteins. This study tracked protein synthesis in mouse epididymis during development, finding key proteins appear early and are influenced by hormones.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Molecular Endocrinology
Background:
- Spermatozoa maturation is essential for fertility.
- Epididymal proteins play a crucial role in sperm maturation.
- Understanding the synthesis and regulation of these proteins is vital.
Purpose of the Study:
- To investigate the synthesis of epididymal proteins during postnatal development in mice.
- To identify age-dependent and region-specific patterns of protein secretion.
- To determine the hormonal regulation of epididymal protein synthesis.
Main Methods:
- In vitro incubation of mouse epididymis tissue with 35S-methionine.
- Analysis of labeled proteins using SDS-PAGE and fluorography.
- Comparison of in vitro synthesized proteins with in vivo cytosol and luminal fluid proteins.
- Hormonal manipulation studies (castration, estrogen, testosterone treatment).
Main Results:
- Peak protein synthesis observed in 7 to 21-day-old mice, decreasing with age.
- Majority of adult secretory proteins present by 7 days of age.
- Distinct proximal and distal epididymal proteins identified at 21 days.
- Hormonal treatments (estrogen, castration) inhibited synthesis; testosterone reversed effects.
Conclusions:
- Epididymal protein synthesis is established early in postnatal development.
- Protein secretion exhibits regional specificity and is developmentally regulated.
- Androgens are critical for the synthesis and secretion of specific epididymal proteins.