Ohlsson R, Holmgren L, Glaser A, Szpecht A, Pfeifer-Ohlsson S
Centre for Biotechnology, Karolinska Institute, Huddinge University Hospital, Sweden.
EMBO J. 1989 Jul;8(7):1993-9. doi: 10.1002/j.1460-2075.1989.tb03606.x.
Substructures of the first-trimester human placenta (within 3 months post-conception) display 'pseudo-malignant' properties. We show here, by in situ hybridization, that the insulin-like growth factor 2 (IGF-2) gene expression is particularly active in the cytotrophoblasts, which dominate these structures. Because the majority of placental IGF-2 mRNA is polysomal in extracts of first-trimester placenta, the spatial pattern of IGF-2 transcripts generally also defines the pattern of IGF-2 production. In primary trophoblast cultures, rendered quiescent by serum starvation. IGF-2 performs as a human embryonic growth factor by activating cell cycle entry/progression. Although both type 1 and 2 IGF receptor mRNAs can be found co-distributed with IGF-2 mRNA during placental development (supporting an autocrine role for IGF-2), these occasional patterns are confined to cytotrophoblasts with low proliferative potential. The reciprocity in ligand and receptor expression patterns are discussed in terms of rate-limiting steps in the involvement of IGF-2 in the proliferative phenotype of the early human placenta.
孕早期（受孕后3个月内）的人胎盘亚结构表现出“假恶性”特征。我们在此通过原位杂交表明，胰岛素样生长因子2（IGF-2）基因表达在主导这些结构的细胞滋养层中特别活跃。由于孕早期胎盘提取物中的大多数胎盘IGF-2 mRNA是多聚核糖体的，IGF-2转录本的空间模式通常也决定了IGF-2的产生模式。在血清饥饿使其静止的原代滋养层细胞培养物中，IGF-2通过激活细胞周期进入/进程发挥人类胚胎生长因子的作用。尽管在胎盘发育过程中可以发现1型和2型IGF受体mRNA与IGF-2 mRNA共同分布（支持IGF-2的自分泌作用），但这些偶尔出现的模式仅限于增殖潜力低的细胞滋养层。从IGF-2参与早期人胎盘增殖表型的限速步骤方面讨论了配体和受体表达模式的相互关系。
