Acute Podocyte Vascular Endothelial Growth Factor (VEGF-A) Knockdown Disrupts alpha(V)beta(3) Integrin Signaling in the Glomerulus

作者：Veron Delma^*; Villegas Guillermo; Aggarwal Pardeep Kumar; Bertuccio Claudia; Jimenez Juan; Velazquez Heino; Reidy Kimberly; Abrahamson Dale R; Moeckel Gilbert; Kashgarian Michael; Tufro Alda

来源：PLos One, 2012, 7(7): e40589.

DOI：10.1371/journal.pone.0040589

Podocyte or endothelial cell VEGF-A knockout causes thrombotic microangiopathy in adult mice. To study the mechanism involved in acute and local injury caused by low podocyte VEGF-A we developed an inducible, podocyte-specific VEGF-A knockdown mouse, and we generated an immortalized podocyte cell line (VEGF(KD)) that downregulates VEGF-A upon doxycycline exposure. Tet-O-siVEGF:podocin-rtTA mice express VEGF shRNA in podocytes in a doxycycline-regulated manner, decreasing VEGF-A mRNA and VEGF-A protein levels in isolated glomeruli to similar to 20% of non-induced controls and urine VEGF-A to similar to 30% of control values a week after doxycycline induction. Induced tet-O-siVEGF: podocin-rtTA mice developed acute renal failure and proteinuria, associated with mesangiolysis and microaneurisms. Glomerular ultrastructure revealed endothelial cell swelling, GBM lamination and podocyte effacement. VEGF knockdown decreased podocyte fibronectin and glomerular endothelial alpha(V)beta(3) integrin in vivo. VEGF receptor-2 (VEGFR2) interacts with beta(3) integrin and neuropilin-1 in the kidney in vivo and in VEGF(KD) podocytes. Podocyte VEGF knockdown disrupts alpha(V)beta(3) integrin activation in glomeruli, detected by WOW1-Fab. VEGF silencing in cultured VEGF(KD) podocytes downregulates fibronectin and disrupts alpha(V)beta(3) integrin activation cell-autonomously. Collectively, these studies indicate that podocyte VEGF-A regulates alpha(V)beta(3) integrin signaling in the glomerulus, and that podocyte VEGF knockdown disrupts alpha(V)beta(3) integrin activity via decreased VEGFR2 signaling, thereby damaging the three layers of the glomerular filtration barrier, causing proteinuria and acute renal failure.

• 出版日期2012-7-13