Loss of PRICKLE1 leads to subfertility, aberrant extracellular matrix and abnormal myometrial architecture in mice.

IN BRIEF: PRICKLE1, a WNT/planar cell polarity (PCP) protein that is downregulated in uterine leiomyoma, plays an important role in myometrial tissue architecture and extracellular matrix (ECM) deposition. This paper shows that myometrial-specific ablation of the mouse Prickle1 gene results in a uterine leiomyoma phenotype. ABSTRACT: Uterine leiomyomas (ULs) are the most prevalent benign tumors of the female reproductive tract, originating from the myometrium and affecting over 75% of reproductive-age women. Symptoms of UL include pelvic pain, pressure, dysmenorrhea, menorrhagia, anemia and reproductive dysfunction. Currently, there is no effective long-term pharmacotherapy for UL, making them the leading cause of hysterectomies in the United States. The lack of treatment options is attributed to the absence of accurate animal models and a limited understanding of UL pathogenesis. Previous research has shown that the loss of repressor of element 1 silencing transcription factor/neuron-restrictive silencing factor (REST/NRSF) within the myometrium promotes UL pathogenesis. In addition, deletion of Rest in the mouse myometrium leads to a UL phenotype. PRICKLE1, also known as Rest-interacting LIM-domain protein (RILP), is required for nuclear localization of REST and Wnt/PCP signaling, making it a critical target for UL studies. In the context of PCP, smooth muscle cells in UL show abnormal organization, aberrant ECM structure and expression levels, potentially influenced by PRICKLE1 loss. The exact role of PRICKLE1 and Wnt/PCP in UL pathogenesis remains unclear. To explore PRICKLE1's role in UL, we deleted Prickle1 using our myometrial-specific iCre. Our findings demonstrate that Prickle1 loss in the myometrium results in a UL phenotype characterized by altered collagen expression, excessive ECM deposition, aberrant smooth muscle cell organization, increased Esr1 and Pgr expression and dysregulated Wnt/PCP signaling. This novel mouse model serves as a valuable preclinical tool for understanding UL pathogenesis and developing future pharmacotherapies.