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Updated: Aug 4, 2026
Quantitative Comparison of cis-Regulatory Element (CRE) Activities in Transgenic Drosophila melanogaster
Published on: December 19, 2011
Differential oocyte-specific expression of Cre recombinase activity in GDF-9-iCre, Zp3cre, and Msx2Cre transgenic
Zi-Jian Lan1, Xueping Xu, Austin J Cooney
1Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
Abstract:
Oocyte-specific deletion of ovarian genes using Cre/loxP technology provides an excellent tool to understand their physiological roles during folliculogenesis, oogenesis, and preimplantation embryonic development. We have generated a transgenic mouse line expressing improved Cre recombinase (iCre) driven by the mouse growth differentiation factor-9 (GDF-9) promoter. The resulting transgenic mouse line was named GDF-9-iCre mice. Using the floxed ROSA reporter mice, we found that Cre recombinase was expressed in postnatal ovaries, but not in heart, liver, spleen, kidney, and brain. Within the ovary, the Cre recombinase was exclusively expressed in the oocytes of primordial follicles and follicles at later developmental stages. The expression of iCre of GDF-9-iCre mice was shown to be earlier than the Cre expression of Zp3Cre and Msx2Cre mice, in which the Cre gene is driven by zona pellucida protein 3 (Zp3) promoter and a homeobox gene Msx2 promoter, respectively, in the postnatal ovary. Breeding wild-type males with heterozygous floxed germ cell nuclear factor (GCNF) females carrying the GDF-9-iCre transgene did not produce any progeny having the floxed GCNF allele, indicating that complete deletion of the floxed GCNF allele can be achieved in the female germline by GDF-9-iCre mice. These results suggest that GDF-9-iCre mouse line provides an excellent genetic tool for understanding functions of oocyte-expressing genes involved in folliculogenesis, oogenesis, and early embryonic development. Comparison of the ontogeny of the Cre activities of GDF-9-iCre, Zp3Cre, and Msx2Cre transgenic mice shows there is sequential Cre activity of the three transgenes that will allow inactivation of a target gene at different points in folliculogenesis.
Insights
We developed a new GDF-9-iCre mouse model for precise oocyte gene deletion. This tool aids research into female reproduction, enabling gene function studies during egg development and early embryogenesis.
Area of Science:
- Reproductive Biology
- Genetics
- Developmental Biology
Background:
- Cre/loxP technology enables targeted gene deletion in specific cell types.
- Understanding gene function in oocytes is crucial for reproductive health.
Purpose of the Study:
- To generate and characterize a novel GDF-9-driven Cre recombinase (iCre) transgenic mouse line.
- To validate its utility for oocyte-specific gene inactivation.
Main Methods:
- Generated GDF-9-iCre transgenic mice.
- Crossed with floxed ROSA reporter mice to assess Cre expression patterns.
- Crossed with floxed germ cell nuclear factor (GCNF) mice to confirm germline deletion efficacy.
Main Results:
- GDF-9-iCre expression was confirmed exclusively in oocytes from primordial to later stages.
- Cre activity onset in GDF-9-iCre mice precedes that of Zp3Cre and Msx2Cre lines.
- Complete deletion of floxed GCNF allele in the female germline was achieved.
Conclusions:
- The GDF-9-iCre mouse line is a valuable genetic tool for studying oocyte-specific gene functions.
- Its early and specific expression pattern allows for precise temporal control of gene inactivation.
- Facilitates research on folliculogenesis, oogenesis, and preimplantation development.
