Levy R, Smith S D, Chandler K, Sadovsky Y, Nelson D M
Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Am J Physiol Cell Physiol. 2000 May;278(5):C982-8. doi: 10.1152/ajpcell.2000.278.5.C982.
Preeclampsia and fetal growth restriction are associated with placental hypoperfusion and villous hypoxia. The villous response to this environment includes diminished trophoblast differentiation and enhanced apoptosis. We tested the hypothesis that hypoxia induces apoptosis in cultured trophoblasts, and that epidermal growth factor (EGF), an enhancer of trophoblast differentiation, diminishes hypoxia-induced apoptosis. Trophoblasts isolated from placentas of term-uncomplicated human pregnancies were cultured up to 72 h in standard (PO(2) = 120 mm Hg) or hypoxic (PO(2) <15 mm Hg) conditions. Exposure to hypoxia for 24 h markedly enhanced trophoblast apoptosis as determined by DNA laddering, internucleosomal in situ DNA fragmentation, and histomorphology, as well as by the reversibility of the apoptotic process with a caspase inhibitor. Apoptosis was accompanied by increased expression of p53 and Bax and decreased expression of Bcl-2. Addition of EGF to cultured trophoblasts or exposure of more differentiated trophoblasts to hypoxia significantly lowered the level of apoptosis. We conclude that hypoxia enhances apoptosis in cultured trophoblasts by a mechanism that involves an increase in p53 and Bax expression. EGF and enhancement of cell differentiation protect against hypoxic-induced apoptosis.
子痫前期和胎儿生长受限与胎盘灌注不足及绒毛缺氧有关。绒毛对这种环境的反应包括滋养层细胞分化减少和凋亡增加。我们检验了以下假设：缺氧诱导培养的滋养层细胞凋亡，而作为滋养层细胞分化增强剂的表皮生长因子（EGF）可减少缺氧诱导的凋亡。从足月正常妊娠的胎盘分离出的滋养层细胞在标准条件（PO₂ = 120 mmHg）或缺氧条件（PO₂ < 15 mmHg）下培养长达72小时。通过DNA梯状条带分析、核小体间原位DNA片段化、组织形态学以及凋亡过程用半胱天冬酶抑制剂的可逆性测定，发现暴露于缺氧24小时显著增强了滋养层细胞凋亡。凋亡伴随着p53和Bax表达增加以及Bcl-2表达减少。向培养的滋养层细胞中添加EGF或使更分化的滋养层细胞暴露于缺氧环境可显著降低凋亡水平。我们得出结论，缺氧通过涉及p53和Bax表达增加的机制增强培养的滋养层细胞凋亡。EGF和细胞分化增强可防止缺氧诱导的凋亡。
