Du Zhao-jiang, Kamei Motohiro, Suzuki Mihoko, Tano Yasuo, Wang Bai-ren, Hui Yan-nian
Department of Ophthalmology, Xijing Hospital, the Fourth Military Medical University, Xi'an, China.
Ophthalmic Res. 2007;39(4):224-31. doi: 10.1159/000104831. Epub 2007 Jun 29.
To investigate the role played by E26 transformation-specific-1 (Ets-1), a transcription factor, and extracellular signal-regulated kinase 1/2 (ERK1/2) in the expression of vascular endothelial growth factor (VEGF), and the interaction of Ets-1 and ERK1/2 in the retina of diabetic rats.
Diabetes was induced in rats by an intraperitoneal injection of streptozotocin (STZ). To follow the time course in the expression of Ets-1, phosphorylated ERK1/2 (pERK1/2), and VEGF, rats were killed at 1, 2, 4, and 8 weeks after the injection of STZ, and total proteins were extracted from the isolated retinas. An adenovirus vector encoding dominant-negative Ets-1 and an inhibitor of PD98059 was injected intravitreally to investigate the effects of Ets-1 blockade and ERK1/2 inhibition on the expression of VEGF. Four weeks after the first intravitreal injection, total proteins and total RNA were extracted from the retinas for Western blot and Northern blot analyses.
The expression of Ets-1, pERK1/2, and VEGF in the retina increased in a time-dependent manner after STZ injection. The phosphorylation of ERK1/2 and protein level of VEGF were significantly reduced following intravitreal Ets-1. Inhibition of ERK1/2 phosphorylation resulted in a significant reduction in the expression of Ets-1 and the level of VEGF protein.
These results indicate that in the retina of STZ-induced diabetic rats: (1) the alterations of Ets-1, pERK1/2, and VEGF are approximately synchronized; (2) the phosphorylation of ERK1/2 is regulated by the expression of Ets-1; (3) the production of Ets-1 protein is dependent on the ERK1/2 pathway, and (4) the protein level of VEGF is regulated by both Ets-1 expression and ERK1/2 phosphorylation. We propose that VEGF, Ets-1, and ERK1 act synergistically in the development of diabetic retinopathy.
研究转录因子E26转化特异性-1（Ets-1）和细胞外信号调节激酶1/2（ERK1/2）在血管内皮生长因子（VEGF）表达中所起的作用，以及Ets-1与ERK1/2在糖尿病大鼠视网膜中的相互作用。
通过腹腔注射链脲佐菌素（STZ）诱导大鼠患糖尿病。为了追踪Ets-1、磷酸化ERK1/2（pERK1/2）和VEGF表达的时间进程，在注射STZ后1、2、4和8周处死大鼠，并从分离的视网膜中提取总蛋白。玻璃体内注射编码显性负性Ets-1的腺病毒载体和PD98059抑制剂，以研究Ets-1阻断和ERK1/2抑制对VEGF表达的影响。在首次玻璃体内注射后4周，从视网膜中提取总蛋白和总RNA，用于蛋白质印迹和Northern印迹分析。
STZ注射后，视网膜中Ets-1、pERK1/2和VEGF的表达呈时间依赖性增加。玻璃体内注射Ets-1后，ERK1/2的磷酸化和VEGF的蛋白水平显著降低。抑制ERK1/2磷酸化导致Ets-1表达和VEGF蛋白水平显著降低。
这些结果表明，在STZ诱导的糖尿病大鼠视网膜中：（1）Ets-1、pERK1/2和VEGF的变化大致同步；（2）ERK1/2的磷酸化受Ets-1表达的调节；（3）Ets-1蛋白的产生依赖于ERK1/2途径；（4）VEGF的蛋白水平受Ets-1表达和ERK1/2磷酸化的调节。我们提出，VEGF、Ets-1和ERK1在糖尿病视网膜病变的发展中协同作用。
