Jacobs A L, Hwang D, Julian J, Carson D D
Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
Endocrinology. 1994 Nov;135(5):1807-15. doi: 10.1210/endo.135.5.7956904.
Our previous studies demonstrated that interleukin-1 alpha (IL-1 alpha) and soluble factors secreted by polarized uterine luminal epithelial cells (UEC) stimulate prostaglandin (PG) secretion by uterine stromal cells (USC). The present studies were aimed at determining the mechanism by which these agonists stimulate PG secretion by USC. The comoplete inhibition of IL-1 alpha- and UEC-induced PGE2 secretion by cycloheximide and actinomycin-D in the presence of a saturating concentration of arachidonic acid indicated that IL-1 alpha and UEC act to a large extent by inducing de novo expression of PG endoperoxide synthase (PGHS). Western blot analysis of membrane fractions from USC showed a 2- to 4-fold accumulation of the mitogen-inducible isoform of PGHS (PGHS-2), but not the constitutively expressed enzyme (PGHS-1), within 3 h of treatment with IL-1 alpha, UEC-conditioned medium, or serum. Inhibition of UEC-stimulated PGHS-2 expression by anti-IL-1 alpha indicated that IL-1 alpha is one factor secreted by UEC responsible for the synthesis of USC PGHS-2. Expression of PGHS-2, but not PGHS-1, was inhibited by dexamethasone. Dexamethasone also inhibited IL-1 alpha- and UEC-stimulated PGE2 secretion by USC. Immunohistochemical studies demonstrated that PGHS-2 is localized to implantation sites in newly differentiating USC at the time of blastocyst attachment, indicating a potential physiological role for PGHS-2 in early stages of mouse implantation. In contrast, PGHS-1 was localized to UEC during this period. Collectively, these results indicate that enhanced PG secretion by USC in response to IL-1 alpha and soluble factors secreted by UEC is due to selective expression of PGHS-2. In addition, the expression of PGHS-2 by USC in vivo during the periimplantation period may support PG secretion required during early stages of embryo implantation.
我们之前的研究表明，白细胞介素-1α（IL-1α）以及极化的子宫腔上皮细胞（UEC）分泌的可溶性因子可刺激子宫基质细胞（USC）分泌前列腺素（PG）。本研究旨在确定这些激动剂刺激USC分泌PG的机制。在花生四烯酸饱和浓度存在的情况下，环己酰亚胺和放线菌素-D对IL-1α和UEC诱导的PGE2分泌的完全抑制表明，IL-1α和UEC在很大程度上通过诱导PG内过氧化物合酶（PGHS）的从头表达发挥作用。对USC膜组分的蛋白质印迹分析显示，在用IL-1α、UEC条件培养基或血清处理3小时内，PGHS的丝裂原诱导同工型（PGHS-2）积累了2至4倍，但组成型表达的酶（PGHS-1）没有积累。抗IL-1α对UEC刺激的PGHS-2表达的抑制表明，IL-1α是UEC分泌的负责USC中PGHS-2合成的一个因子。地塞米松抑制PGHS-2而非PGHS-1的表达。地塞米松还抑制IL-1α和UEC刺激的USC分泌PGE2。免疫组织化学研究表明，在胚泡附着时，PGHS-2定位于新分化的USC中的着床部位，这表明PGHS-2在小鼠着床早期具有潜在的生理作用。相比之下，在此期间PGHS-1定位于UEC。总体而言，这些结果表明，USC对IL-1α和UEC分泌的可溶性因子作出反应而增强的PG分泌是由于PGHS-2的选择性表达。此外，围植入期体内USC对PGHS-2的表达可能支持胚胎着床早期所需的PG分泌。
