Glomerular-specific alterations of VEGF-A expression lead to distinct congenital and acquired renal diseases
J. Clin. Invest. Vera Eremina, et al. 111:707 doi:10.1172/JCI17423 [Go to this article.]

Figure 1
Expression and genomic targeting of VEGF-A within the glomerular filtration barrier. (a) Transmission electron micrograph of the glomerular filtration barrier that consists of podocytes (po) and their specialized foot processes (fp), fenestrated endothelium (en), and intervening GBM. VEGF-A is produced in the podocyte; the VEGF receptors Flk1 and Flt1 are expressed in the adjacent endothelial cells. (b) Development of the glomerular filtration barrier. In the S-shape stage, podocyte precursors (po) express VEGF-A. Endothelial cells (en) that express the VEGF receptors migrate into the vascular (Vasc) cleft and differentiate in direct apposition to podocytes. In the mature glomerulus, the fenestrated endothelial capillary loops (cap) remain in intimate contact with the VEGF-expressing podocytes (po). Mesangial cells (me) provide support to the capillary tuft. Urine is formed as blood (bl) is filtered from the capillaries, across the GBM, and through slit diaphragms that connect adjacent podocyte foot processes (fp). (c) Scheme to generate heterozygous and homozygous podocyte-specific VEGF knockout mice. Triangles are 34 bp loxP sites. (d) The Cre recombinase transgene was identified as a 300 bp PCR product. The floxed VEGF allele measures 140 bp by PCR analysis, whereas the wild-type allele measures 100 bp. MW, molecular weight markers. (e) Transgenic construct used to overexpress the 164-isoform of VEGF. pA, poly(A). (f) Presence of the transgenic VEGF-164 gene was identified as a 1.3-kb band (*) by Southern blot analysis. (g) Dot blot analysis of transgene copy number. The transgenic founder mice (164) demonstrated a 30-fold increase in copy number compared with the wild type.