Yamamoto T, Chapman B M, Clemens J W, Richards J S, Soares M J
Department of Physiology, University of Kansas Medical Center, Kansas City 66160, USA.
Mol Cell Endocrinol. 1995 Sep 22;113(2):183-94. doi: 10.1016/0303-7207(95)03628-k.
Trophoblast giant cell differentiation is accompanied by transcriptional activation of the cytochrome P-450 side-chain cleavage (P450scc) gene. The Rcho-1 trophoblast cell line has the capacity to differentiate along the trophoblast giant cell lineage and has been used to study trophoblast-specific P450scc gene expression. In this report, P450scc gene promoter activities in trophoblast-specific P450scc gene expression. In this report, P450scc gene promoter activities in trophoblast cells have been mapped and the involvement of known modulators of steroid hydroxylase gene expression, the cyclic AMP/protein kinase A pathway and steroidogenic factor-1 (SF-1), evaluated. Comparisons were made with Y-1 adrenal and R2C Leydig cells. The cumulative results from transient and stable transfection experiments implicate the region between -428 and -511 bp of 5'-flanking DNA in the developmental activation of the P450scc promoter during trophoblast giant cell differentiation. Differences in basal activities of the P450scc promoter constructs were also observed in Y-1 adrenal and R2C Leydig cells; however, the magnitude of the differences was modest. Activators of the protein kinase A pathway stimulated P450scc promoter activity in Y-1 cells, whereas similar treatment of Rcho-1 trophoblast cells did not stimulate but actually inhibited P450scc promoter activity. The inhibitory activity was localized between -639 and -894 bp of the P450scc promoter. SF-1 mRNA and protein were detected in adrenal and gonadal cells but not in rat placenta or Rcho-1 trophoblast cells by Northern and Western blotting, respectively. Thus, P450scc gene activation during trophoblast cell differentiation involves an 83-bp region of its 5'-flanking DNA between -428 and -511 but does not appear to involve cyclic AMP-activated pathways or SF-1. In conclusion, the mechanism of P450scc gene activation during trophoblast cell differentiation appears different from the regulation of P450scc gene activation in other steroidogenic tissues.
滋养层巨细胞分化伴随着细胞色素P-450侧链裂解（P450scc）基因的转录激活。Rcho-1滋养层细胞系有能力沿着滋养层巨细胞谱系分化，并已被用于研究滋养层特异性P450scc基因的表达。在本报告中，对滋养层细胞中P450scc基因启动子活性进行了定位，并评估了已知的类固醇羟化酶基因表达调节剂、环磷酸腺苷/蛋白激酶A途径和类固醇生成因子-1（SF-1）的参与情况。与Y-1肾上腺细胞和R2C睾丸间质细胞进行了比较。瞬时和稳定转染实验的累积结果表明，在滋养层巨细胞分化过程中，P450scc启动子5'侧翼DNA中-428至-511 bp之间的区域参与了P450scc启动子的发育激活。在Y-1肾上腺细胞和R2C睾丸间质细胞中也观察到了P450scc启动子构建体基础活性的差异；然而，差异的幅度较小。蛋白激酶A途径的激活剂刺激了Y-1细胞中的P450scc启动子活性，而对Rcho-1滋养层细胞进行类似处理并未刺激反而抑制了P450scc启动子活性。抑制活性定位于P450scc启动子的-639至-894 bp之间。分别通过Northern印迹和Western印迹在肾上腺和性腺细胞中检测到了SF-1 mRNA和蛋白，但在大鼠胎盘或Rcho-1滋养层细胞中未检测到。因此，滋养层细胞分化过程中P450scc基因的激活涉及其5'侧翼DNA中-428至-511之间的83 bp区域，但似乎不涉及环磷酸腺苷激活途径或SF-1。总之，滋养层细胞分化过程中P450scc基因激活的机制似乎不同于其他类固醇生成组织中P450scc基因激活的调节机制。
