Sasa H, Umekage T, Namima M, Arimura S, Nakata H, Watanabe Y, Kobayashi M
Department of Perinatal and Maternal Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan.
Placenta. 1997 Jul-Aug;18(5-6):427-31. doi: 10.1016/s0143-4004(97)80043-4.
Ras GTPase-activating protein (GAP), an important downregulator of Ras activity, has previously been shown to be abundant in human placenta. The expression of p120 and p100 isoforms of GAP in human normal chorionic villi (n=5) and hydatidiform mole (n=5) was investigated to clarify the involvement of Ras GAP in the growth of chorionic villi in the first trimester of pregnancy. Immunoblot analysis revealed that both p120- and p100-GAP isoforms were remarkably less expressed in mole villi than in normal chorionic villi. The expression of p100-GAP significantly reduced in comparison with that of pl20-GAP in mole villi. Northern blot analysis showed that the amount of GAP mRNA reduced in hydatidiform mole less than one-third of that in normal chorionic villi. The GAP activity, measured by the effect of tissue extract on the hydrolysis of Ras-bound GTP, was significantly lower in hydatidiform mole than in normal chorionic villi. These results suggest that Ras GAP may play an important role in the normal growth and differentiation of human chorionic villi in the first trimester.
Ras鸟苷三磷酸酶激活蛋白（GAP）是Ras活性的重要负调控因子，此前已证明其在人胎盘中含量丰富。为阐明Ras GAP在妊娠早期绒毛膜绒毛生长中的作用，研究了GAP的p120和p100亚型在人正常绒毛膜绒毛（n = 5）和葡萄胎（n = 5）中的表达。免疫印迹分析显示，与正常绒毛膜绒毛相比，葡萄胎绒毛中p120和p100-GAP亚型的表达均显著降低。与p120-GAP相比，葡萄胎绒毛中p100-GAP的表达显著降低。Northern印迹分析表明，葡萄胎中GAP mRNA的量减少至正常绒毛膜绒毛的三分之一以下。通过组织提取物对Ras结合的GTP水解的影响来测量的GAP活性，在葡萄胎中显著低于正常绒毛膜绒毛。这些结果表明，Ras GAP可能在妊娠早期人绒毛膜绒毛的正常生长和分化中起重要作用。
