SAT-198 Increased Expression of YAP Is Associated with the Decreased Cell Autophagy in the Eutopic Endometrial Stromal Cells of Women with Endometriosis

Endometriosis (EMS) is a debilitating gynecologic disease characterized by the presence of endometrial glands and stroma outside the uterus. Symptoms caused by this disease have serious implications for women's lives and health. Although it has been widely studied recent years, the exact pathogenesis of endometriosis is not fully clear. Basic researches have shown that the signal pathways play significant roles in the development and progression of EMS (1). We first reported the Hippo-YAP (Yes-associated protein) pathway promotes cell proliferation and anti-apoptosis in endometrial stromal cells (ESCs) of EMS (2). It is well known that autophagy with normal metabolic condition is important to sustain cell growth and function. It has been reported that cell autophagy involves in the pathogenesis of EMS and endometrial regulation through multi-level and multipath interference in EMS (3). Wilkinson et al. found that phosphorylation of LC3 by STK3/STK4, the mammalian homologs of Hippo which can antagonize YAP activity, is an essential step in the autophagy process (4). It hints that there may be an elaborate dialogue between Hippo-YAP and autophagy. To explore the role of YAP in the regulation of cell autophagy in the eutopic ESCs, we performed in vitro studies to investigate the expressions of YAP pathway and cell autophagy markers (mTOR, LC-3) in ESCs of women with or without EMS and detect the protein levels of autophagy markers in the eutopic ESCs after the transfection with YAP-knockdown vector and Verteporfin treatment, the inhibitor of YAP-TEAD complex, in ESCs, respectively. The mRNA levels of YAP and mTOR were all increased in the eutopic ECSs of women with EMS compared with controls (1.56 ± 0.37 vs. 1.04 ± 0.17; 0.49 ± 0.12 vs. 0.31 ± 0.08; P>0.05). Similarly, the protein levels of YAP (0.85 ± 0.13 vs. 0.35 ± 0.04; P<0.05) and mTOR (0.81 ± 0.03 vs. 0.37 ± 0.01; P<0.01) were significantly increased in the eutopic ECSs of women with EMS compared with controls. To the contrary, the ratio of the autophagy marker protein LC3-II/LC3-I (1.36 ± 0.06 vs. 2.17 ± 0.19; P<0.05) was significantly decreased in the eutopic ECSs of women with EMS compared with controls. Furthermore, YAP knockdown and Verteporfin treatment in the eutopic ESCs increased the level of cell autophagy with an increased ratio of the autophagy marker protein LC3-II/LC3-I (1.15 ± 0.05 vs. 0.87± 0.04; P<0.05). Therefore, our study demonstrates that the decreased cell autophagy level is associated with the increased expression of YAP in the eutopic ESCs and it may be negatively regulated by YAP. Reference: (1) Choi et al., Mol Hum Reprod. 2014, 20(4): 309-17. (2) Song et al., J Clin Endocrinol Metab. 2016, 101: 1552-61. (3) Mei et al., Hum Reprod. 2015, 30: 1677-89. (4) Wilkinson et al., Mol Cell. 2015; 57:55-68.