Cyp19a1-Cre-EGFP: A placenta-specific Cre transgenic mouse model for targeted gene recombination in trophoblast cells.

Objective: The placenta plays a critical role in fetal development, yet placenta-specific gene manipulation remains a challenge due to widespread gene expression across maternal and embryonic tissues. Here, we describe the generation and characterization of Cyp19a1-Cre-EGFP transgenic mice, a novel Cre-loxP model for placenta-specific gene recombination.

Methods: A Cyp19a1-Cre-EGFP construct was generated using the Cyp19a1 promoter, driving Cre recombinase expression with an enhanced green fluorescent protein (EGFP) reporter. Transgenic mice were produced via pronuclear microinjection and backcrossed to establish stable Cre-expressing lines. Tissue specificity of Cre-EGFP expression was assessed by confocal microscopy, immunofluorescence, and PCR genotyping at embryonic day 13.5 (E13.5). To validate Cre-mediated recombination, Cyp19a1-CreEGFP mice were crossed with Nr3c1 (glucocorticoid receptor floxed) mice, and gene knockdown efficiency was evaluated by immunostaining.

Results: Cyp19a1-Cre-EGFP mice exhibited exclusive Cre expression in placental trophoblast cells, with no detectable EGFP fluorescence in maternal tissues (ovary, amygdala) or fetal liver. Transgenic mice displayed normal growth, fertility, and placental morphology. Cre-mediated recombination resulted in significant knockdown of GR expression (P < 0.05), confirming the model's efficiency for placenta-specific gene deletion.

Conclusion: The Cyp19a1-Cre-EGFP mouse model provides a highly specific and efficient tool for placental gene manipulation. Its applications extend to studying placental development, pregnancy disorders, and fetal programming, with potential relevance for preclinical models of placental disease.