Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA.
Kidney Int. 2010 Jun;77(11):989-99. doi: 10.1038/ki.2010.64. Epub 2010 Mar 10.
We sought to examine the pathogenic role of excessive VEGF-A expression in podocytes, since it has been reported that diabetic nephropathy and other glomerular diseases are associated with increased VEGF-A expression. The induction of podocyte-specific VEGF164 overexpression in adult transgenic mice led to proteinuria, glomerulomegaly, glomerular basement membrane thickening, mesangial expansion, loss of slit diaphragms, and podocyte effacement. When doxycycline-mediated VEGF164 was stopped, these abnormalities reversed. These findings were associated with reversible downregulation of metalloproteinase 9 and nephrin expression. Using transmission electron microscopy, we established that VEGF-A receptor-2 (VEGFR2) was expressed in podocytes and glomerular endothelial cells. We also found that VEGF164 induced VEGFR2 phosphorylation in podocytes. Further, we were able to co-immunoprecipitate VEGFR2 and nephrin using whole kidney lysates, confirming interaction in vivo. This implies that autocrine and paracrine VEGF-A signaling through VEGFR2 occurs in podocytes and may mediate the glomerular phenotype caused by VEGF164 overexpression. Thus, we suggest that podocyte VEGF164 overexpression in adult mice is sufficient to induce glomerular filtration barrier structural and functional abnormalities similar to those present in murine diabetic nephropathy.
我们试图研究血管内皮生长因子 A（VEGF-A）在足细胞中过度表达的致病作用，因为据报道，糖尿病肾病和其他肾小球疾病与 VEGF-A 表达增加有关。在成年转基因小鼠中诱导足细胞特异性 VEGF164 过表达导致蛋白尿、肾小球肿大、肾小球基底膜增厚、系膜扩张、裂孔隔膜丢失和足细胞消失。当用强力霉素介导的 VEGF164 停止时，这些异常得到逆转。这些发现与金属蛋白酶 9 和nephrin 表达的可逆下调有关。通过透射电子显微镜，我们确定 VEGF-A 受体-2（VEGFR2）在足细胞和肾小球内皮细胞中表达。我们还发现 VEGF164 在足细胞中诱导 VEGFR2 磷酸化。此外，我们能够使用整个肾裂解物共免疫沉淀 VEGFR2 和 nephrin，从而在体内证实相互作用。这意味着通过 VEGFR2 的自分泌和旁分泌 VEGF-A 信号在足细胞中发生，并可能介导由 VEGF164 过表达引起的肾小球表型。因此，我们建议成年小鼠足细胞 VEGF164 过表达足以诱导类似于糖尿病肾病中存在的肾小球滤过屏障结构和功能异常。
