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Sequential activation of Notch family receptors during mouse spermatogenesis
Shintaro Mori1, Yuzo Kadokawa, Kiyotaka Hoshinaga
1Department of Urology, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan. shintaro@fujita-hu.ac.jp
Abstract:
The expression pattern of Notch family receptors during mouse spermatogenesis was examined by immunohistochemistry. The entire cytoplasm of spermatogonia, spermatocytes and spermatids showed staining with antibodies against extracellular domains of Notch1, 2 and 4. In contrast, the nuclei of spermatogonia showed staining with an antibody against the intracellular domain of Notch3, and the nuclei of spermatocytes and spermatids showed staining with antibodies against the intracellular domains of Notch1 and 4. During regeneration of spermatogonia in busulfan-treated mice, the nuclei of all proliferating cells showed staining for the intracellular domain of Notch3. Western blot analysis showed that the molecular weights of the intracellular domains of Notch1 and 3 localizing in the nuclear fraction were smaller than those in the cytoplasmic fraction. This was consistent with the theory that the intracellular domain of Notch was cleaved in the cytoplasm and translocated to the nucleus. These results suggest that different Notch signals are sequentially activated during mouse spermatogenesis and control the proliferation and differentiation of spermatogenic stem cells.
Insights
Notch signaling in male germ cells is crucial for reproduction. This study reveals Notch receptors
Area of Science:
- Reproductive Biology
- Cell Signaling
- Developmental Biology
Background:
- Spermatogenesis is a complex process involving germ cell proliferation and differentiation.
- Notch signaling pathways are known to regulate cell fate decisions in various developmental processes.
Purpose of the Study:
- To investigate the expression patterns and localization of Notch family receptors during mouse spermatogenesis.
- To elucidate the role of Notch signaling in the regulation of spermatogenic stem cell proliferation and differentiation.
Main Methods:
- Immunohistochemistry was employed to detect Notch receptor expression in different stages of spermatogenesis.
- Western blot analysis was used to examine the molecular weights of Notch intracellular domains in cytoplasmic and nuclear fractions.
- Studies were conducted on busulfan-treated mice to observe spermatogonial regeneration.
Main Results:
- Extracellular domains of Notch1, 2, and 4 were found throughout the cytoplasm of spermatogonia, spermatocytes, and spermatids.
- Intracellular domains of Notch3 localized to spermatogonial nuclei, while Notch1 and 4 intracellular domains were in the nuclei of spermatocytes and spermatids.
- Cleavage and nuclear translocation of Notch intracellular domains were observed, with smaller molecular weights in the nuclear fraction.
Conclusions:
- Sequential activation of distinct Notch signals occurs during mouse spermatogenesis.
- Notch signaling plays a critical role in controlling the proliferation and differentiation of spermatogenic stem cells.