Investigating the Molecular Mechanism of Hexose-induced Stress in Lens and Retina

糖尿病是一个迅速增长的公共卫生问题。对高血糖症的控制不足导致糖尿病的“晚期并发症”的发作和进展，其在眼睛中包括白内障和糖尿病性视网膜病变，这两者都导致视力丧失。先前对糖尿病和半乳糖血症动物的研究已经证明，糖性白内障形成和与糖尿病视网膜病变相关的视网膜血管改变都与通过多元醇途径与过量醛糖还原酶活性相关的渗透压和氧化应激有关。过量的醛糖还原酶活性也与信号转导变化、细胞毒性信号和细胞凋亡的激活有关。初步研究还表明，醛糖还原酶的活性与胁迫相关的基因表达变化有关。在本授权申请中，我们拟阐明透镜和视网膜中醛糖还原酶活性和己糖诱导的氧化应激与眼内胰岛素样生长因子（IGF）、转化生长因子（TGF-β）和碱性成纤维细胞生长因子（b-FGF）水平改变相关的机制，这三种生长因子被观察到参与白内障形成和糖尿病视网膜病变。将评估IGF和TGF-β信号通路中MAPK、PI-3 K、SMAD 3以及凋亡因子半胱天冬酶3、p53和p38的水平。此外，将使用Fox（IGF 1）、SMAD 3或4（TGF-β）或SAPK/JNK（b-FGF）转录因子，通过微阵列分析鉴定IGF、TGF-β和b-FGF信号传导途径的主要靶基因。这些研究将在糖尿病和半乳糖喂养的大鼠以及正常和转基因小鼠中进行，其中视网膜周细胞含有增加水平的醛糖还原酶。通过阐明这种与己糖相关的氧化应激的来源，并确定醛糖还原酶改变眼内b-FGF、IGF和TGF-β水平的具体机制，以及它们相关的信号通路和基因表达，可以获得对白内障和糖尿病视网膜病变治疗的新见解。此外，这些研究应该有助于确定治疗这些糖尿病并发症的新药物靶点。

DESCRIPTION: Diabetes is a rapidly increasing public health problem. Inadequate control of hyperglycemia leads to the onset and progression of the "late complications" of diabetes mellitus which in the eye include cataract and diabetic retinopathy, both of which result in vision loss. Previous studies with diabetic and galactosemic animals have demonstrated that both sugar cataract formation and retinal vascular alterations associated with diabetic retinopathy are linked to osmotic and oxidative stress associated with excess aldose reductase activity through the polyol pathway. Excess aldose reductase activity has also been linked to signal transduction changes, cytotoxic signals and activation of apoptosis. Preliminary studies also indicate that aldose reductase activity is linked to stress-related gene expression changes. In this grant application, we propose to elucidate the mechanism(s) by which aldose reductase activity and hexose-induced oxidative stress in the lens and retina are linked to altered ocular levels of insulin-like growth factor (IGF), transforming growth factor (TGF-beta) and basic fibroblast growth factor (b-FGF), three growth factors observed to be involved in cataract formation and diabetic retinopathy. The levels of MAPK, PI-3K, SMAD3 in the signaling pathways of IGF and TGF-beta and the apoptotic factors, caspase 3, p53, and p38 will be assessed. In addition, the major target genes of IGF, TGF-beta , and b-FGF signaling pathways will be identified using the Fox (IGF1), SMAD3 or 4 (TGF-p), or SAPK/JNK (b-FGF) transcriptional factors with microarray analysis. These studies will be conducted in diabetic and galactose-fed rats and in normal and transgenic mice in which the retinal pericytes contain increased levels of aldose reductase. By clarifying the source of this hexose-linked oxidative stress and identifying the specific mechanism(s) through which aldose reductase alters the ocular levels of b-FGF, IGF and TGF-beta, their associated signaling pathways and gene expression, new insights into the treatment for cataract and diabetic retinopathy can be obtained. Moreover, these studies should help identify new drug targets for the treatment of these diabetic complications.