Transcriptional Regulation in the Uterine Luminal Epithelium

Evelyn Carrion (Advisor: Richard Behringer, PhD)

          The uterus is an organ comprised of multiple tissues that are essential for women’s health and reproduction. The uterus has three different layers, the perimetrium, myometrium, and the endometrium (Gasner et al., 2023). The endometrium is the inner region of the uterus, and contains the luminal epithelium, glandular epithelium, and stroma. The luminal epithelium is a columnar layer of cells that is necessary for embryo implantation. The uterus is derived in part from the embryonic precursor tissue called the Müllerian duct. There are no known enhancers that drive transcription in the uterine luminal epithelium or Müllerian duct. Wnt7a expression has been reported in both the uterine luminal epithelium and Müllerian ducts. Wnt7a expression in the uterine luminal epithelium is required for proper uterine differentiation and fertility (Parr et al., 1998).  Previously, the Behringer lab used a 245 kb BAC (bacterial artificial chromosome) containing the Wnt7a locus to introduce a Cre gene into exon 2 to create a transgenic mouse line. Crosses with a ROSA26-lacZ reporter line showed that the 245 kb region contained the cis regulatory elements to drive reporter expression in the Müllerian duct epithelium. The GENSAT organization created a BAC transgenic mouse resource to study brain gene expression.  They used the same 245 kb BAC with the Wnt7a locus to generate a Wnt7a-EGFP mouse line. I found EGFP expression in the Müllerian ducts and adult uterine luminal epithelium. Based on these data, I hypothesized that the cis regulatory element(s) responsible for Wnt7a transcription in the luminal epithelium and Müllerian duct is contained within the 245kb genomic region. To test this hypothesis, I used ATAC-seq of purified uterine luminal epithelial cells to define the genome-wide open chromatin landscape. Analysis of the 245 kb BAC region identified tissue-specific open chromatin domains that are candidate regions for Wnt7a Müllerian duct and uterine luminal epithelium transcriptional enhancers. In addition, the transcriptomes of purified uterine luminal epithelial cells were generated by RNA-seq to identify cell-type specific expression. These studies define the open chromatin landscape of uterine luminal epithelial cells and should lead to the identification of cis-regulatory elements that direct uterine luminal epithelial cell and Müllerian duct-specific expression.

Advisory Committee:

• Richard Behringer, PhD, Chair
• Jain Abhinav, PhD
• Stephanie Pangas, PhD
• Heidi Kaplan, PhD
• Yoshihiro Komatsu, PhD

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