(187) Characterization of the (tetO)7-Cre Mouse Model for Inducible Gene Expression in Pregnancy Research

Characterization of the (tetO)7-Cre Mouse Model for Inducible Gene Expression in Pregnancy Research

Hruda Malik¹, Keisuke Kozai¹, Gracy Rosario¹, Sabita Dhal¹, Prashanth Anamthathmakula¹, and Nihar R Nayak¹

¹Department of Obstetrics and Gynecology, UMKC School of Medicine, Kansas City, USA

Abstract Text:

Placental dysfunctions are a leading cause of various pregnancy-related disorders. Despite this, our understanding of the molecular mechanisms governing placental development and function, especially in the context of pregnancy diseases, remains limited due to the lack of effective gene manipulation techniques specific to the placenta. Recent advancements in conditional placenta-specific gene targeting, such as the Cre/loxP recombination system, have shown promise for gene knockins and knockouts in the placenta. However, these methods have limitations in analyzing gene activity at specific stages of pregnancy and placental development, as they lack precise, pregnancy stage-specific on-off control of gene expression. This is critical, as many placental genes exhibit expression patterns that vary with pregnancy stages. Consequently, there is a need for more versatile, controllable expression systems that facilitate in-depth functional analysis across different developmental stages. The doxycycline-inducible Cre-loxP system, particularly the (tetO)7-Cre [Tg(tetO-cre)1Jaw/J] mouse model, offers powerful tissue- and time-specific genetic manipulation and has been widely utilized in other tissues. However, reports of spontaneous Cre recombination (Cre leakiness) in some tissues raised concerns regarding its suitability for pregnancy studies. In this study, we evaluated the (tetO)7-Cre mouse strain for its application in Tet-inducible gene expression during pregnancy, focusing on spontaneous Cre recombination in the placenta, uterus, and fetus at various stages of gestation, as well as in the non-pregnant uterus, using the Ai6 fluorescence Cre reporter mice. Although no spontaneous Cre recombination was observed in the placenta, Cre recombination was detected in both the pregnant and non-pregnant uterus at different gestational days. Additionally, significant Cre recombination was observed in fetal tissues. Therefore, careful consideration of appropriate controls is essential when interpreting results from the (tetO)7-Cre mouse model in pregnancy-related studies.