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Role of c-kit in mouse spermatogenesis: identification of spermatogonia as a specific site of c-kit expression and
K Yoshinaga1, S Nishikawa, M Ogawa
1Department of Anatomy, Kumamoto University Medical School, Japan.
Abstract:
Recent studies have shown that the dominant white spotting (W) locus encodes the proto-oncogene c-kit, a member of the tyrosine kinase receptor family. One symptom of mice bearing mutation within this gene is sterility due to developmental failure of the primordial germ cells during early embryogenesis. To elucidate the role of the c-kit in gametogenesis, we used an anti-c-kit monoclonal antibody, ACK2, as an antagonistic blocker for c-kit function to interfere with the development of male and female germ cells during postnatal life. ACK2 enabled us to detect the expression of c-kit in the gonadal tissue and also to determine the functional status of c-kit, which is expressed on the surface of a particular cell lineage. Consistent with our immunohistochemical findings, the intravenous injection of ACK2 into adult mice caused a depletion in the differentiating type A spermatogonia from the testis during 24-36 h, while the undifferentiated type A spermatogonia were basically unaffected. Intraperitoneal injections of ACK2 into prepuberal mice could completely block the mitosis of mature (differentiating) type A spermatogonia, but not the mitosis of the gonocytes and primitive type A spermatogonia, or the meiosis of spermatocytes. Our results indicate that the survival and/or proliferation of the differentiating type A spermatogonia requires c-kit, but the primitive (undifferentiated) type A spermatogonia or spermatogenic stem cells are independent from c-kit. Moreover, the antibody administration had no significant effect on oocyte maturation despite its intense expression of c-kit.
Insights
The proto-oncogene c-kit is crucial for the survival and proliferation of differentiating spermatogonia in mice. However, primitive spermatogonia and oocyte maturation are not dependent on c-kit function.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Oncogenes
Background:
- The white spotting (W) locus encodes the proto-oncogene c-kit, a tyrosine kinase receptor.
- Mutations in c-kit cause sterility in mice due to primordial germ cell developmental failure.
- Understanding c-kit's role in gametogenesis is essential for reproductive health research.
Purpose of the Study:
- To investigate the function of c-kit in postnatal male and female gametogenesis.
- To determine the specific cell types and developmental stages dependent on c-kit.
- To utilize an antagonistic anti-c-kit antibody (ACK2) to block c-kit activity.
Main Methods:
- Administration of ACK2 monoclonal antibody to adult and prepubertal mice.
- Immunohistochemical analysis to detect c-kit expression in gonadal tissue.
- Monitoring the effects of ACK2 on spermatogonia populations and oocyte maturation.
Main Results:
- ACK2 injection depleted differentiating type A spermatogonia in adult mice within 24-36 hours.
- In prepubertal mice, ACK2 blocked mitosis of mature type A spermatogonia but not gonocytes or primitive type A spermatogonia.
- Meiosis of spermatocytes and oocyte maturation were unaffected by ACK2 administration.
- Primitive type A spermatogonia (stem cells) are independent of c-kit for survival and proliferation.
Conclusions:
- C-kit signaling is required for the survival and/or proliferation of differentiating type A spermatogonia.
- Spermatogenic stem cells (primitive type A spermatogonia) do not require c-kit.
- Oocyte maturation is independent of c-kit function, despite its expression.