Department of Obstetrics and Gynecology, National Cheng Kung University Hospital, 138 Sheng-Li Road, Tainan, 704, Taiwan.
Department of Biomedical Sciences, Chung Shan Medical University, No.110, Sec. 1, Jianguo N. Rd., South Dist, Taichung City, 402, Taiwan.
Reprod Biol Endocrinol. 2017 Aug 15;15(1):66. doi: 10.1186/s12958-017-0286-x.
Nucleotide-binding oligomerization domain (NACHT), leucine rich repeat (LRR) and pyrin domain (PYD) 7 containing protein, NLRP7, is a member of the NLR family which serves as innate immune sensors. Mutations and genetic variants of NLRP7 have been found in women with infertility associated conditions, such as recurrent hydatidiform mole, recurrent miscarriage, and preeclampsia. Decidualization of endometrial stromal cells is a hallmark of tissue remodeling to support embryo implantation and proper placental development. Given defective decidualization has been implicated in miscarriage as well as preeclampsia, we aimed to explore the link between the NLRP7 gene and decidualization.
Endometrial samples obtained from pregnant women in the first trimester and non-pregnant women were used to study NLRP7 expression pattern. The human telomerase reverse transcriptase (hTERT)-immortalized human endometrial stromal cells (T-HESCs) were used to study the effect of NLRP7 on decidualization. Decidualization of T-HESCs was induced with 1 μM medroxyprogesterone acetate (MPA) and 0.5 mM 8-bromoadenosine 3':5'-cyclic monophosphate (8-Br-cAMP). siRNA was used to knock down NLRP7 while lentiviral vectors were used to overexpress NLRP7 in cells. NLRP7 expression was detected by immunofluorescence, qRT-PCR, and Western blotting. Decidualization markers, Insulin-like growth factor-binding protein 1 (IGFBP-1) and prolactin (PRL), were detected by qRT-PCR and ELISA. Nuclear translocation of NLRP7 was detected by the subcellular fractionation and confocal microscopy. The effect of NLRP7 on progesterone receptor (PR) activity was evaluated by a reporter system.
NLRP7 was up-regulated in the decidual stromal cells of human first-trimester endometrium. After in vitro decidualization, T-HESCs presented with the swollen phenotype and increased expressions of IGFBP-1 and PRL. Knockdown or over-expression of NLRP7 reduced or enhanced the decidualization, respectively, according to the expression level of IGFBP-1. NLRP7 was found to translocate in the nucleus of decidualized T-HESCs and able to promote PR activity.
NLRP7 was upregulated and translocated to the nucleus of the endometrial stromal cells in an in vitro decidualization model. Overexpressed NLRP7 promoted the IGFBP-1 expression and PR reporter activation. IGFBP-1 expression decreased with the knockdown of NLRP7. Therefore, we suggest that NLRP7 contributes to in vitro decidualization of endometrial stromal cells.
核苷酸结合寡聚化结构域（NACHT）、富含亮氨酸重复序列（LRR）和吡咯啉-5-羧酸域（PYD）7 包含蛋白（NLRP7）是 NLR 家族的成员之一，作为先天免疫传感器。NLRP7 的突变和遗传变异已在与不孕相关的女性中发现，如复发性葡萄胎、复发性流产和子痫前期。子宫内膜基质细胞的蜕膜化是组织重塑的标志，以支持胚胎着床和适当的胎盘发育。鉴于蜕膜化缺陷与流产以及子痫前期有关，我们旨在探讨 NLRP7 基因与蜕膜化之间的联系。
从妊娠早期和非妊娠女性中获取子宫内膜样本，用于研究 NLRP7 的表达模式。使用人端粒酶逆转录酶（hTERT）永生化的人子宫内膜基质细胞（T-HESCs）研究 NLRP7 对蜕膜化的影响。用 1 μM 醋酸甲羟孕酮（MPA）和 0.5 mM 8-溴环磷酸腺苷（8-Br-cAMP）诱导 T-HESCs 蜕膜化。用 siRNA 敲低 NLRP7，用慢病毒载体过表达细胞中的 NLRP7。通过免疫荧光、qRT-PCR 和 Western blot 检测 NLRP7 的表达。通过 qRT-PCR 和 ELISA 检测胰岛素样生长因子结合蛋白 1（IGFBP-1）和催乳素（PRL）等蜕膜化标志物。通过亚细胞分离和共聚焦显微镜检测 NLRP7 的核转位。通过报告系统评估 NLRP7 对孕激素受体（PR）活性的影响。
NLRP7 在人早孕子宫内膜的蜕膜基质细胞中上调。体外蜕膜化后，T-HESCs 呈现肿胀表型，IGFBP-1 和 PRL 的表达增加。根据 IGFBP-1 的表达水平，NLRP7 的敲低或过表达分别减少或增强了蜕膜化。发现 NLRP7 在蜕膜化的 T-HESCs 中转位到核内，并能促进 PR 活性。
在体外蜕膜化模型中，NLRP7 在子宫内膜基质细胞中被上调并转位到核内。过表达的 NLRP7 促进 IGFBP-1 的表达和 PR 报告基因的激活。NLRP7 敲低后 IGFBP-1 的表达减少。因此，我们认为 NLRP7 有助于子宫内膜基质细胞的体外蜕膜化。
