The effect of melatonin on the cell proliferation

晚期糖基化终产物（AGEs）被认为在糖尿病血管病变的发展中起重要作用。先前的报道表明，AGEs的积累与人类糖尿病视网膜血管内皮生长因子（VEGF）的产生之间存在相关性。然而，所涉及的机制并未透露。在这项研究中，我们研究了AGEs对血管内皮生长因子（VEGF）表达的转录调控，以及活性氧（EOS）在诱导中的可能参与。我们采用了牛血清白蛋白（BSA）的AGE，由BSA与d -葡萄糖和N(epsilon)（羧甲基）赖氨酸（CML）（一种主要的AGE）孵育40周制备。CML-BSA诱导vegf在RAW264.7小鼠巨噬细胞样细胞中的表达。CML-BSA刺激激活蛋白-1 （AP-1）的dna结合活性。启动子实验表明，vegf的诱导依赖于AP- 1。Ras/ Raf- II MEK/ ERK1/2的活性参与CML-BSA刺激的信号通路，激活AP-1转录，并在1 h达到峰值。AGE-BSA也能诱导AP-1介导的VEGF，但AGE-BSA和CML-BSA对AP-1的激活作用存在差异。age - bsa刺激的AP-1活性在5 h达到峰值，与ROS的形成平行。用NaBH4或添加维生素E减少AGE-BSA会减弱AGE-BSA刺激的信号通路，导致与cml - bsa刺激信号相同的模式。这些结果表明，在糖尿病并发症中观察到，AGEs在刺激血管生成的发展中起重要作用，ROS加速了age刺激的VEGF表达。

Advanced glycation end products (AGEs) are believed to play an important role in the development of angiopathy in diabetes mellitus. Previous reports suggested a correlation between accumulation of AGEs and production of vascular endothelial growth factor (VEGF) in human diabetic retina. However, the mechanisms involved were not revealed. In this study, we investigated the transcriptional reg ulation of the expression of vascular endothelial growth factor (VEGF) by AGEs, and possible involve ment of reactive oxygen species (EOS) in the induction. We employed an AGE of bovine serum albumin (BSA) prepared by an incubation of BSA with D-glucose for 40 weeks and N(epsilon) (carboxymethyl)lysine (CML), a major AGE. The expression ofVEGF was induced by CML-BSA in RAW264.7 mouse macrophage like cells. CML-BSA stimulated the DNA-binding activity of activator protein- 1 (AP-1). Promoter assay showed that the induction of VEGFwas dependent on AP- 1. The activity of Ras/ Raf- II MEK/ ERK1/2 was involved in the CML-BSA-stimulated signaling pathways to activate the AP-1 transcription with a peak at 1 h. AGE-BSA also induced VEGF mediated by AP-1, however, there was a difference of effect between AGE-BSA and CML-BSA in the activation ofAP-1. AGE-BSA-stimulated AP-1 activity showed a peak at 5 h, which paralleled the formation of ROS. Reduction of AGE-BSA with NaBH4 or addition of vitamin E attenuated the AGE-BSA-stimulated signaling pathways leading to the same pattern as for CML-BSA-stimulated signals. These results suggest an important role for AGEs in stimulation of the development of angiogenesis observed in dia betic complications, and that ROS accelerates the AGE-stimulated VEGF expression.