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Female fertility is reduced in mice lacking Ca2+/calmodulin-dependent protein kinase IV
J Y Wu1, I J Gonzalez-Robayna, J S Richards
1Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Abstract:
Ca2+/calmodulin-dependent protein kinase IV (CaMKIV) is a serine/threonine protein kinase with limited tissue distribution. CaMKIV is highly expressed in the testis, where it is found in transcriptionally inactive elongating spermatids. We have recently generated mice deficient in CaMKIV. In the absence of CaMKIV, the exchange of sperm nuclear basic proteins in male spermatids is impaired, resulting in male infertility secondary to defective spermiogenesis. The involvement of CaMKIV in female fertility has not been addressed. Here we report that female fertility is markedly reduced in CaMKIV-deficient mice due to impaired follicular development and ovulation. CaMKIV is expressed in the ovary, where it is localized in granulosa cells. We further find that in cultured granulosa cells, CaMKIV expression and subcellular localization are hormonally regulated. As granulosa cells differentiate, CaMKIV levels decrease and the kinase translocates from the nucleus into the cytoplasm. Our results demonstrate a critical role for CaMKIV in female reproduction and point to a potential function in granulosa cell differentiation.
Insights
Calcium/calmodulin-dependent protein kinase IV (CaMKIV) deficiency impairs female fertility by affecting ovarian follicular development and ovulation. This kinase plays a crucial role in granulosa cell differentiation.
Area of Science:
- Reproductive Biology
- Molecular Endocrinology
- Cellular Signaling
Background:
- Calcium/calmodulin-dependent protein kinase IV (CaMKIV) is a serine/threonine protein kinase with restricted tissue expression.
- CaMKIV is highly expressed in the testis, where its absence leads to male infertility due to impaired spermiogenesis.
- The role of CaMKIV in female reproduction remained uninvestigated.
Purpose of the Study:
- To investigate the role of CaMKIV in female fertility.
- To determine the expression and localization of CaMKIV in the ovary.
- To explore the regulation of CaMKIV in ovarian granulosa cells.
Main Methods:
- Generation and analysis of CaMKIV-deficient mice.
- Assessment of female reproductive parameters, including follicular development and ovulation.
- Immunohistochemical analysis of CaMKIV expression in ovarian tissues.
- In vitro studies using cultured granulosa cells to examine CaMKIV regulation.
Main Results:
- CaMKIV-deficient female mice exhibit significantly reduced fertility.
- Impaired follicular development and ovulation were observed in CaMKIV-deficient females.
- CaMKIV is expressed in ovarian granulosa cells and its expression/localization is hormonally regulated.
- CaMKIV levels decrease and translocate from nucleus to cytoplasm during granulosa cell differentiation.
Conclusions:
- CaMKIV plays a critical role in female reproductive function.
- CaMKIV is essential for normal follicular development and ovulation.
- CaMKIV is implicated in the process of granulosa cell differentiation.