Zhao Xiaojian, Eghbali-Webb Mahboubeh
Department of Anesthesiology, Yale School of Medicine, New Haven, CT, USA.
Endocrine. 2002 Jul;18(2):137-45. doi: 10.1385/ENDO:18:2:137.
Previously we showed that cardiac fibroblasts are cellular targets of estrogen and that there are significant differences in proliferative response of male and female cardiac fibroblasts under hypoxia, a condition of myocardial ischemia. Here, we tested the hypothesis that signaling pathways that control cell cycle progression and apoptosis in cardiac fibroblasts may be activated in a gender-specific manner. Cardiac fibroblasts from adult, age-matched male and female rat heart were exposed to hypoxia (2% O2) and normoxia. Western analysis of cell lysate was used to compare the level of basal and hypoxia-induced expression of signal transduction proteins, known to control cell cycle progression and cell death. Hypoxia led to significant activation of MAP (mitogen-activated protein) kinase and Jun kinase pathways, as shown by phosphorylated extracellular signal-regulated kinase (ERK1/2) and Jun kinase isotypes in male cells but this effect was modest in female cells. Male cells expressed higher levels of basal expression for transcription factors c-jun and NF-kB as well as the inhibitor of NF-kB (lk-B). Although hypoxia did not induce changes in the level of c-Jun in either cell type, it moderately increased the level of NF-kB in male cells but led to its decrease in female cells. Basal and hypoxia-induced expression of cyclin D1, c-fos, and PCNA seemed to be comparable in both male and female cells. However, hypoxia-induced activation of cyclin B1, which occurred in both cells, was stronger in female cells. Basal expression of apoptosis-associated transcription factor, p53, was comparable in both cells. However, under hypoxia, there was an increase in the p53 level only in female cells. Although female cells showed higher basal expression for survival-associated protein, Bcl-2, the level of this protein remained unchanged under hypoxia in both cells. Together, these data demonstrate differences in basal and hypoxia-induced expression of proteins with an established role in cell cycle progression and apoptosis in male and female cardiac fibroblasts. These differences may further point to gender-related differences in signal transduction pathways that control the proliferative response of those cells under hypoxia.
先前我们发现心脏成纤维细胞是雌激素的细胞靶点，并且在心肌缺血状态即缺氧情况下，雄性和雌性心脏成纤维细胞的增殖反应存在显著差异。在此，我们检验了这样一个假设，即控制心脏成纤维细胞细胞周期进程和凋亡的信号通路可能以性别特异性方式被激活。将成年、年龄匹配的雄性和雌性大鼠心脏的心脏成纤维细胞暴露于缺氧（2%氧气）和常氧环境。利用细胞裂解物的蛋白质印迹分析来比较已知控制细胞周期进程和细胞死亡的信号转导蛋白的基础表达水平以及缺氧诱导的表达水平。缺氧导致丝裂原活化蛋白（MAP）激酶和Jun激酶通路显著激活，雄性细胞中磷酸化的细胞外信号调节激酶（ERK1/2）和Jun激酶同工型显示了这一效应，但在雌性细胞中这种效应较弱。雄性细胞中转录因子c-jun和NF-kB以及NF-kB抑制剂（lk-B）的基础表达水平较高。尽管缺氧在两种细胞类型中均未诱导c-Jun水平发生变化，但它使雄性细胞中NF-kB水平适度增加，而导致雌性细胞中NF-kB水平下降。细胞周期蛋白D1、c-fos和增殖细胞核抗原（PCNA）的基础表达和缺氧诱导表达在雄性和雌性细胞中似乎相当。然而，缺氧诱导的细胞周期蛋白B1激活在两种细胞中均有发生，在雌性细胞中更强。凋亡相关转录因子p53的基础表达在两种细胞中相当。然而，在缺氧条件下，仅雌性细胞中p53水平升高。尽管雌性细胞中存活相关蛋白Bcl-2的基础表达较高，但在缺氧条件下两种细胞中该蛋白水平均保持不变。总之，这些数据证明了在雄性和雌性心脏成纤维细胞中，在细胞周期进程和凋亡中起既定作用的蛋白质的基础表达和缺氧诱导表达存在差异。这些差异可能进一步表明在缺氧情况下控制这些细胞增殖反应的信号转导通路存在性别相关差异。
