School of Physiology, Pharmacology and Neurosciences, University of Bristol, UK.
Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK.
J Physiol. 2017 Oct 1;595(19):6281-6298. doi: 10.1113/JP274481. Epub 2017 Jul 3.
Progressive depletion of all vascular endothelial growth factor A (VEGF-A) splice isoforms from the kidney results in proteinuria and increased glomerular water permeability, which are both rescued by over-expression of VEGF-A b only. VEGF-A b rescues the increase in glomerular basement membrane and podocyte slit width, as well as the decrease in sub-podocyte space coverage, produced by VEGF-A depletion. VEGF-A b restores the expression of platelet endothelial cell adhesion molecule in glomerular endothelial cells and glomerular capillary circumference. VEGF-A b has opposite effects to VEGF-A on the expression of genes involved in endothelial cell migration and proliferation.
Chronic kidney disease is strongly associated with a decrease in the expression of vascular endothelial growth factor A (VEGF-A). However, little is known about the contribution of VEGF-A splice isoforms to kidney physiology and pathology. Previous studies suggest that the splice isoform VEGF-A b (resulting from alternative usage of a 3' splice site in the terminal exon) is protective for kidney function. In the present study, we show, in a quad-transgenic model, that over-expression of VEGF-A b alone is sufficient to rescue the increase in proteinuria, as well as glomerular water permeability, in the context of progressive depletion of all VEGF-A isoforms from the podocytes. Ultrastructural studies show that the glomerular basement membrane is thickened, podocyte slit width is increased and sub-podocyte space coverage is reduced when VEGF-A is depleted, all of which are rescued in VEGF-A b over-expressors. VEGF-A b restores the expression of platelet endothelial cell adhesion molecule-1 in glomerular endothelial cells and glomerular capillary circumference. Mechanistically, it increases VEGF receptor 2 expression both in vivo and in vitro and down-regulates genes involved in migration and proliferation of endothelial cells, otherwise up-regulated by the canonical isoform VEGF-A . The results of the present study indicate that manipulation of VEGF-A splice isoforms could be a novel therapeutic avenue in chronic glomerular disease.
从肾脏中逐渐耗尽所有血管内皮生长因子 A（VEGF-A）剪接异构体导致蛋白尿和肾小球水通透性增加，而过表达 VEGF-A b 可完全挽救这两种情况。VEGF-A b 可挽救 VEGF-A 耗竭引起的肾小球基底膜和足突裂孔宽度增加以及足突下细胞空间覆盖率降低。VEGF-A b 可恢复肾小球内皮细胞中血小板内皮细胞黏附分子和肾小球毛细血管周长的表达。VEGF-A b 对涉及内皮细胞迁移和增殖的基因的表达有与 VEGF-A 相反的作用。
慢性肾脏病与血管内皮生长因子 A（VEGF-A）表达降低密切相关。然而，对于 VEGF-A 剪接异构体对肾脏生理和病理的贡献知之甚少。先前的研究表明，剪接异构体 VEGF-A b（通过在末端外显子中使用 3' 剪接位点的选择性使用产生）对肾功能具有保护作用。在本研究中，我们在四重转基因模型中表明，在逐渐耗尽足细胞中所有 VEGF-A 异构体的情况下，单独过表达 VEGF-A b 就足以挽救蛋白尿增加和肾小球水通透性增加。超微结构研究表明，当 VEGF-A 耗尽时，肾小球基底膜增厚，足突裂孔宽度增加，足突下细胞空间覆盖率降低，而过表达 VEGF-A b 可全部挽救。VEGF-A b 恢复了血小板内皮细胞黏附分子-1 在肾小球内皮细胞和肾小球毛细血管周长的表达。在体内和体外，它都增加了 VEGF 受体 2 的表达，并下调了内皮细胞迁移和增殖相关基因的表达，而这些基因在经典同工型 VEGF-A 存在时被上调。本研究结果表明，VEGF-A 剪接异构体的操纵可能成为慢性肾小球疾病的一种新的治疗途径。
