Wogensen L, Nielsen C B, Hjorth P, Rasmussen L M, Nielsen A H, Gross K, Sarvetnick N, Ledet T
Research Laboratory of Biochemical Pathology and the Medical Research Laboratory, Institute of Pathology, Aarhus Kommunehospital, Denmark.
Diabetes. 1999 Jan;48(1):182-92. doi: 10.2337/diabetes.48.1.182.
Our purpose was to elucidate the hypothesis that paracrine-produced transforming growth factor (TGF)-beta1 regulates the accumulation of extracellular matrix (ECM) in renal glomeruli, a hallmark of diabetic nephropathy. To produce TGF-beta1 from the juxtaglomerular apparatus in mouse kidneys, we cloned a mouse Ren-1c promoter fragment (-4.100 to +6 base pairs) upstream of porcine TGF-beta1 (pTGF-beta1) cDNA, mutated to ensure secretion of biologically active TGF-beta beta1. The resulting transgenic mice had significantly more TGF-beta1 in their kidneys than was in those of nontransgenic controls, as confirmed by immunohistochemistry, and the production of TGF-beta1 was enhanced in vivo by captopril-induced stimulation of the Ren-1c promoter. Overproduction of pTGF-beta1 close to the glomerulus resulted in a local accumulation of ECM, composed partly of collagen type IV and laminin, and thickening of the basement membrane, characteristic features of diabetic nephropathy. Interstitial accumulation of ECM and signs of tubular atrophy were present only in older mice (>5 months of age). Results from in situ hybridization and immunohistochemistry suggest that pTGF-beta1 stimulated the production of endogenous TGF-beta1 along collecting ducts and connecting tubules. The increased amount of biologically active TGF-beta1, transgenic as well as endogenous, was corroborated by heightened proteoglycan synthesis from incubated kidney slices. This transgenic model demonstrates that sustained local expression of TGF-beta1 leads to glomerulopathy. We conclude that autocrine- or paracrine-produced TGF-beta1 may play a role in the development of glomerular diseases, such as diabetic nephropathy.
我们的目的是阐明旁分泌产生的转化生长因子（TGF）-β1调节肾小球细胞外基质（ECM）积聚这一假说，ECM积聚是糖尿病肾病的一个标志。为了从小鼠肾脏的肾小球旁器产生TGF-β1，我们在猪TGF-β1（pTGF-β1）cDNA上游克隆了一个小鼠Ren-1c启动子片段（-4.100至+6个碱基对），并进行了突变以确保生物活性TGF-β1的分泌。免疫组织化学证实，所得转基因小鼠肾脏中的TGF-β1明显多于非转基因对照小鼠，并且卡托普利诱导的Ren-1c启动子刺激在体内增强了TGF-β1的产生。靠近肾小球的pTGF-β1过量产生导致ECM局部积聚，部分由IV型胶原和层粘连蛋白组成，以及基底膜增厚，这是糖尿病肾病的特征性表现。ECM的间质积聚和肾小管萎缩迹象仅在老年小鼠（>5月龄）中出现。原位杂交和免疫组织化学结果表明，pTGF-β1刺激了沿集合管和连接小管的内源性TGF-β1的产生。孵育的肾切片中蛋白聚糖合成增加证实了转基因和内源性生物活性TGF-β1的量增加。这个转基因模型表明，TGF-β1的持续局部表达会导致肾小球病变。我们得出结论，自分泌或旁分泌产生的TGF-β1可能在肾小球疾病如糖尿病肾病的发展中起作用。
