Gu Y, Jayatilak P G, Parmer T G, Gauldie J, Fey G H, Gibori G
Department of Physiology and Biophysics, University of Illinois College of Medicine, Chicago 60612.
Endocrinology. 1992 Sep;131(3):1321-8. doi: 10.1210/endo.131.3.1380439.
During decidualization, cells of the endometrium grow and differentiate giving rise to two different decidual tissues located in either the antimesometrial or mesometrial site of the uterus in the rat. These tissues have different functions in pregnancy. The antimesometrial decidua is an endocrine gland that secretes hormones, whereas the mesometrial decidua appears to play an important role in limiting trophoblast invasion. Since the decidual tissue of the rat produces alpha 2-macroglobulin (alpha 2MG), we examined whether this potent protease inhibitor is specifically expressed by the mesometrial tissue, the site of trophoblast invasion, and whether the alph 2MG gene is regulated by decidual luteotropin (DLt), the PRL-like hormone secreted by the neighboring antimesometrial cells. To determine the secretory proteins of the rat decidua, antimesometrial and mesometrial tissues were dissected out from pseudopregnant rats and cultured with [35S]methionine. The major protein secreted by the antimesometrial cell was the 29-kilodalton decidual luteotropin, whereas a 180-kilodalton protein was predominantly secreted by the mesometrial tissue. Immunoprecipitation studies of 35S-radiolabeled proteins revealed that this high mol wt protein is alpha 2MG and that it is secreted exclusively by the cells forming the mesometrial tissue. To examine whether the alpha 2MG gene was also expressed specifically in the mesometrial decidua, total RNA was isolated from both mesometrial and antimesometrial tissues of day 9-12 pseudopregnant rats and hybridized with alpha 2MG cDNA. Northern blot analysis revealed a 5.4-kilobase message, which was abundantly expressed in the mesometrial decidua. Little, if any, alpha 2MG mRNA was detected in antimesometrial decidua. The ontogeny of the message in the decidua correlated well with the development of the mesometrial tissue. To examine whether alpha 2MG expression is regulated by DLt and/or PRL, a highly specific polyclonal antibody to DLt was generated and decidual tissues were cultured in the presence or absence of DLt antibodies with or without PRL. Neutralization of DLt caused a marked decrease in alpha 2MG mRNA levels. This down-regulation was totally reversed by the addition of PRL and was not affected by alpha 2MG antibodies. In summary, the results of this investigation revealed a compartmentalized gene expression, synthesis and secretion of alpha 2MG in the decidua. The secretion of this protease inhibitor, specifically by the mesometrial tissue which is the site of trophoblast invasion, may be the reason for the minimal amount of tissue damage that occurs during placentation.(ABSTRACT TRUNCATED AT 400 WORDS)
在蜕膜化过程中，子宫内膜细胞生长并分化，在大鼠子宫的反系膜或系膜部位形成两种不同的蜕膜组织。这些组织在妊娠中具有不同的功能。反系膜蜕膜是一种分泌激素的内分泌腺，而系膜蜕膜似乎在限制滋养层侵入方面起重要作用。由于大鼠的蜕膜组织产生α2-巨球蛋白（α2MG），我们研究了这种强效蛋白酶抑制剂是否由滋养层侵入部位的系膜组织特异性表达，以及α2MG基因是否受相邻反系膜细胞分泌的催乳素样激素——蜕膜促黄体素（DLt）的调节。为了确定大鼠蜕膜的分泌蛋白，从假孕大鼠中分离出反系膜和系膜组织，并用[35S]甲硫氨酸进行培养。反系膜细胞分泌的主要蛋白是29千道尔顿的蜕膜促黄体素，而系膜组织主要分泌一种180千道尔顿的蛋白。对35S放射性标记蛋白的免疫沉淀研究表明，这种高分子量蛋白是α2MG，且仅由形成系膜组织的细胞分泌。为了研究α2MG基因是否也在系膜蜕膜中特异性表达，从第9至12天假孕大鼠的系膜和反系膜组织中分离总RNA，并与α2MG cDNA杂交。Northern印迹分析显示有一条5.4千碱基大小的条带，在系膜蜕膜中大量表达。在反系膜蜕膜中几乎检测不到α2MG mRNA（如果有的话也很少）。蜕膜中该条带的个体发生与系膜组织的发育密切相关。为了研究α2MG的表达是否受DLt和/或催乳素调节，制备了一种针对DLt的高度特异性多克隆抗体，并在有无DLt抗体以及有无催乳素的情况下培养蜕膜组织。DLt的中和导致α2MG mRNA水平显著降低。添加催乳素可完全逆转这种下调，且不受α2MG抗体的影响。总之，本研究结果揭示了蜕膜中α2MG的分区基因表达、合成和分泌。这种蛋白酶抑制剂由滋养层侵入部位的系膜组织特异性分泌，可能是胎盘形成过程中组织损伤最小的原因。（摘要截短至400字）
