Study on file RAGE signaling in vascular cells - a novel mechanism of the development of diabetic vascular complications

在这项研究中，我们提供了第一个直接的体内证据，证明晚期糖基化终产物（AGE）与其受体RAGE之间的相互作用导致糖尿病血管紊乱。我们还发现了RAGE的细胞保护性分泌形式（内源性分泌RAGE， esRAGE）在人体中存在，并鉴定了新的RAGE配体，这些配体大量存在于人体循环中。(1)建立了在血管细胞中过表达人RAGE的转基因小鼠。糖尿病RAGE转基因小鼠表现出糖尿病肾病的加速发展。这种转基因小鼠将是一种有用的动物模型，可以显示人类肾脏的变化。(2)我们还建立了在心脏中过表达人类RAGE的转基因小鼠，并获得证据表明AGE和RAGE可能在糖尿病引起的心功能障碍的发展中发挥积极作用。(3)我们构建RAGE基因敲除小鼠，发现在糖尿病敲除小鼠中，晚期糖尿病肾病得到明显抑制。(4)我们证明了人血管内皮细胞（EC）和周细胞表达一种新的剪接变体，编码一种新的RAGE分泌形式（esRAGE）。AGE对EC中ERK磷酸化和血管内皮生长因子以及EC生长和索状结构形成的诱导作用被RAGE变体完全消除，表明esRAGE对AGE具有细胞保护作用。这些发现可能有助于我们理解细胞对AGE反应多样性的分子基础，以及糖尿病血管并发症易感性或耐受性的个体差异。(5)我们发现甘油醛和乙醇醛衍生的AGE是新的RAGE配体。AGE组提高了人EC中VEGF mRNA水平和细胞生长。这些结果提示甘油醛和乙醇醛衍生的AGE参与糖尿病血管损伤。

In this research, we provide the first direct in vivo evidence that interactions between advanced glycation end products (AGE) and their receptor, RAGE, lead to diabetic vascular derangements. We also found the presence of a cytoprotective secretory form of RAGE (endogenous secretory RAGE, esRAGE) in human and identified new RAGE ligands, which are abundantly present in human circulation.(1) We created transgenic mice that overexpress human RAGE in vascular cells. The diabetic RAGE transgenic mice exhibited an accelerated development of diabetic nephropathy. This transgenic mouse will be a useful animal model that shows the renal changes seen in humans.(2) We also created transgenic mice that overexpress human RAGE in the heart and obtained evidence suggesting that the AGE and RAGE could play an active role in the development of diabetes-induced cardiac dysfunction.(3) We created RAGE gene-knockout mice and showed that the advanced diabetic nephropathy was significantly suppressed in the diabetic knockout mice.(4) We demonstrated that human vascular endothelial cells (EC) and pericytes express a novel splice variant encoding a novel secretory form of RAGE (esRAGE). The AGE induction of ERK phosphorylation and vascular endothelial growth factor in EC and of the growth and cord-like structure formation of EC was perfectly abolished by this RAGE variant, indicating that esRAGE is cytoprotective against AGE. The findings may contribute to our understanding of the molecular basis for the diversity of cellular responses to AGE and for individual variations in susceptibility or resistance to diabetic vascular complications.(5) We identified glyceraldehyde- and glycolaldehydee-derived AGE as new RAGE ligands. The AGE fractions increased VEGF mRNA levels in human EC as well as cell growth. These results suggested that glyceraldehyde- and glycolaldehyde-derived AGE participate in vascular injury in diabetes.