Shim C, Choi D, Kwon H B, Kim K
Department of Molecular Biology, College of Natural Sciences, Seoul National University, Korea.
Mol Reprod Dev. 1997 Oct;48(2):176-84. doi: 10.1002/(SICI)1098-2795(199710)48:2<176::AID-MRD5>3.0.CO;2-P.
Laminin may be involved in uterine re-organization and embryo attachment to the uterine wall during the peri-implantation period. In the present study using a competitive reverse transcription-polymerase chain reaction (RT-PCR), the precise expression patterns of laminin chain (A, B1, and B2)-specific mRNAs were examined in mouse uterine tissues during the peri-implantation period. Although Northern blot hybridization failed to detect laminin A chain mRNA in mouse uterus, RT-PCR analysis showed that laminin A chain mRNA was present even at the lower level compared with B1 and B2 chain mRNA levels. Competitive RT-PCR revealed that approximately 3 x 10(6), 3.6 x 10(7), and 4 x 10(8) copies of A, B1, and B2 chain mRNA transcripts were present in 1 microgram of total RNA isolated from the uterus. During pregnancy, the A chain mRNA level was significantly increased only from day 6 after post-hCG when embryo attachment and decidualization started. Elevated level of A chain mRNA was sustained thereafter. Laminin A chain mRNA synthesized at this period was mainly originated from stroma decidual cells. The discrete elevation of laminin A chain mRNA level was also observed after estrogen stimulation in the delayed implantation model. Estrogenic stimulation to ovariectomized, progesterone-treated pregnant mice resulted in about a three-fold increase of laminin A chain mRNA levels. In contrast to A chain mRNA, both B1 and B2 chain mRNA levels were insignificantly altered during the peri-implantation period and delayed implantation by an estrogenic stimulation. Taken together, our results for the first time demonstrate that: (1) laminin A chain mRNA as well as B chain mRNAs is expressed in mouse uterus, (2) its mRNA level is significantly increased along with implantation process, and (3) ovarian steroids, especially estrogen, are likely to be involved in the regulation of laminin gene expression in the uterus.
层粘连蛋白可能在植入前期参与子宫重构以及胚胎与子宫壁的附着过程。在本研究中，运用竞争性逆转录-聚合酶链反应（RT-PCR），检测了植入前期小鼠子宫组织中层粘连蛋白链（A、B1和B2）特异性mRNA的精确表达模式。尽管Northern印迹杂交未能在小鼠子宫中检测到层粘连蛋白A链mRNA，但RT-PCR分析显示，与B1和B2链mRNA水平相比，层粘连蛋白A链mRNA即便水平较低也依然存在。竞争性RT-PCR显示，从子宫分离的1微克总RNA中存在约3×10⁶、3.6×10⁷和4×10⁸个A、B1和B2链mRNA转录本拷贝。在妊娠期间，仅在hCG注射后第6天胚胎附着和蜕膜化开始时，A链mRNA水平才显著升高。此后A链mRNA水平持续升高。此期间合成的层粘连蛋白A链mRNA主要来源于基质蜕膜细胞。在延迟着床模型中，雌激素刺激后也观察到层粘连蛋白A链mRNA水平的离散性升高。对去卵巢、经孕酮处理的妊娠小鼠进行雌激素刺激，导致层粘连蛋白A链mRNA水平增加约三倍。与A链mRNA相反，在植入前期和雌激素刺激引起的延迟着床期间，B1和B2链mRNA水平均无明显变化。综上所述，我们的结果首次表明：（1）层粘连蛋白A链mRNA以及B链mRNA在小鼠子宫中表达；（2）其mRNA水平随着床过程显著升高；（3）卵巢类固醇，尤其是雌激素，可能参与子宫中层粘连蛋白基因表达的调控。
