Jones Rebecca L, Salamonsen Lois A, Zhao Yi Chen, Ethier Jean-François, Drummond Ann E, Findlay Jock K
Prince Henry's Institute of Medical Research, P.O.Box 5152, Clayton, Victoria 3168, Australia.
Mol Hum Reprod. 2002 Apr;8(4):363-74. doi: 10.1093/molehr/8.4.363.
Decidualization of the human endometrium is critical for implantation, but the mechanisms involved are largely unknown. Activin subunits are expressed in endometrium during decidualization. From its known actions in cell differentiation and tissue remodelling, we hypothesized that activin A is involved in the paracrine regulation of decidualization. We examined the expression of activin receptors (ActRs) by semi-quantitative and real-time RT-PCR. mRNA for all ActR subtypes (Ia, Ib, IIa and IIb) was detected in endometrium, with maximal expression in the early secretory phase and in early pregnancy. ActR protein was localized exclusively to stromal and endothelial cells. This expression pattern was confirmed by in-situ hybridization. Activin bioavailability is locally regulated by its binding protein, follistatin, and also by the antagonist, inhibin. Inhibin competition for ActRII binding is enhanced by the binding protein, betaglycan. Follistatin and betaglycan were also detected in the endometrium, localized to stromal and epithelial cells. This co-expression of activin subunits, receptors and binding proteins indicates that stromal cells are capable of responding to activin, and that there is tight local regulation of activin action within the endometrium. As activin production is up-regulated in decidual cells, this provides further evidence for an involvement of activins during stromal cell decidualization.
人子宫内膜的蜕膜化对于着床至关重要，但其涉及的机制在很大程度上尚不清楚。在蜕膜化过程中，激活素亚基在子宫内膜中表达。基于其在细胞分化和组织重塑中的已知作用，我们推测激活素A参与了蜕膜化的旁分泌调节。我们通过半定量和实时逆转录聚合酶链反应检测了激活素受体（ActRs）的表达。在子宫内膜中检测到了所有ActR亚型（Ia、Ib、IIa和IIb）的信使核糖核酸，在分泌期早期和妊娠早期表达最高。ActR蛋白仅定位于基质细胞和内皮细胞。这种表达模式通过原位杂交得到证实。激活素的生物利用度受其结合蛋白卵泡抑素以及拮抗剂抑制素的局部调节。结合蛋白β聚糖可增强抑制素对ActRII结合的竞争。在子宫内膜中也检测到了卵泡抑素和β聚糖，定位于基质细胞和上皮细胞。激活素亚基、受体和结合蛋白的这种共表达表明基质细胞能够对激活素作出反应，并且子宫内膜内存在对激活素作用的严格局部调节。由于蜕膜细胞中激活素的产生上调，这为激活素参与基质细胞蜕膜化提供了进一步的证据。
