PATHOLOGY OF BASEMENT MEMBRANE COMPONENTS IN DIABETES

糖尿病有严重的微血管并发症，导致多系统并发症。 涉及基底膜和细胞外基质的异常。 糖尿病肾脏表现多处病变：肾小球基底区 膜(GBM)功能异常，系膜扩张， 基底膜呈进行性增厚。GBM和系膜矩阵是 由：IV型、V型胶原、蛋白多糖、纤维连接蛋白(FN)、 层粘连蛋白(LMN)和牙本质蛋白等。在众多分子中 糖尿病患者肾小球和血浆的异常表现为：1)增加 系膜FN，2)降低硫酸乙酰肝素蛋白多糖，3) IV型胶原的非酶糖基化增加，以及4)增加 FN的非酶糖基化。FN或胶原的非酶糖基化 降低了这些分子的结合亲和力。的约束性 纤维连接蛋白和胶原(明胶或IV型)或层粘连蛋白和IV型 胶原蛋白，导致与~3H-肝素结合的正协同作用。 FN、LMN或胶原的非酶糖基化(S)导致深刻的 肝素结合的正协同性降低。糖基化 层粘连蛋白还会直接减少与其结合的肝素。这个 拟议的研究将对正常和 非酶糖化FN、LMN、肝素、硫酸肝素蛋白多糖 来源于肾小球和EHS肿瘤，天然胶原蛋白(IV，I和III)， Clq和纤维蛋白。我们将定义绑定类型IV的FN的域 胶原蛋白，并进一步定义I型胶原蛋白(明胶)结合域。这 将涉及蛋白质分解和化学裂解和纯化各种 纤维连接蛋白的结构域。接下来我们将确定存款和营业额 静脉注射放射性标记的FN和非酶糖化的FN。 正常动物和糖尿病动物的给药。接下来，我们将确定是否 肾小球内纤维连接蛋白积聚或周转增加。 来自正常动物和糖尿病动物的培养。最后，我们将分离血浆 从控制不佳的糖尿病人身上检测纤维连接蛋白是否 显示出上述相同的异常现象。总的来说，这些 研究将使我们能够调查可能是一种关键的生化 糖尿病的基底膜和系膜的异常，即心烦意乱 相关分子的分子缔合。一种等离子体的评估 蛋白质可作为微血管病变和 糖尿病患者的肾脏病变是非常吸引人的。它 似乎很清楚，这些研究也可能揭示这一过程 控制基底成分的合成、周转和积累。

Diabetes has profound microvascular complications which lead to multisystem abnormalities involving the basement membrane and extracellular matrix. The diabetic kidney manifests much pathology where: glomerular basement membrane (GBM) function is abnormal, the mesangium becomes expanded and there is a progressive thickening of GBM. The GBM and mesangial matrix are composed of: type IV, V collagens, proteoglycans, fibronectin (FN), laminin (LMN), and entactin, among other things. Among numerous molecular abnormalities in the glomerulus and plasma in diabetes are: 1) increased FN in the mesangium, 2) decreased heparan sulfate proteoglycan, 3) increased nonenzymatic glycation of type IV collagen, and 4) increased nonenzymatic glycation of FN. Nonenzymatic glycation of FN or collagen decreases the binding avidity of these molecules. The binding of fibronectin and collagen (gelatin or type IV) or laminin and type IV collagen, leads to positive cooperativity for 3H-heparin binding. Nonenzymatic glycation of FN, LMN or collagen(s) leads to a profound decrease in positive cooperativity for heparin binding. Glycation of laminin also produces a direct decrease in heparin binding to it. The proposed studies will perform binding assays with normal and nonenzymatically glycated FN, LMN, heparin, heparan sulfate proteoglycan derived from glomeruli and the EHS tumor, native collagens (IV, I and III), Clq and fibrin. We will define the domain of FN that binds type IV collagen and further define the collagen I (gelatin) binding domain. This will involve proteolytic and chemical cleavage and purification of various domains of fibronectin. We will next determine the deposition and turnover of radiolabeled FN and nonenzymatically glycated FN following I.V. administration of normal and diabetic animals. Next, we will determine if there is increased accumulation or turnover of fibronectin in glomerular cultures from normal and diabetic animals. Lastly, we will isolate plasma fibronectin from poorly controlled diabetic humans to determine whether it demonstrates the same abnormalities described above. Collectively these studies will allow us to investigate what may be a key biochemical abnormality in the diabetic GBM and mesangium, namely the perturbed molecular association of relevant molecules. Evaluation of a plasma protein which could serve as an indicator for the microangiopathic and nephropathic changes that are occurring in diabetes is very attractive. It seems clear that these studies may also shed light on the processes governing synthesis, turnover, and accumulation of basement constituents.