BACKGROUND: VEGF secreted by organ parenchymal cells controls vascularization by recruiting endothelial cells and supporting their proliferation. In the developing kidney VEGF-expressing epithelial cells also express VEGF receptors. We showed that VEGF stimulates tubulogenesis in addition to promoting vascularization in metanephric explants. Since explants are grown in serum-free media and are not perfused, we hypothesized that VEGF secreted by renal epithelia may induce their proliferation in an autocrine manner and chemoattract endothelial cells. METHODS: To test these hypotheses, we analyzed VEGF-mediated responses in vitro using several renal epithelial cell lines [immortalized rat proximal tubular cells (IRPT), transformed mouse proximal tubular cells (tsMPT), and normal rat kidney cells (NRK-52E)] expressing VEGF receptors (VEGFR). RESULTS: We demonstrated that VEGFR-2 phosphorylates upon human recombinant VEGF (rhVEGF) exposure, indicating that VEGFR-2 is the signaling receptor. All three cell lines secreted VEGF into the media as indicated by enzyme-linked immunosorbent assay (ELISA) and Western blotting. We showed that these tubular epithelial cells chemoattract endothelial cells when cocultured in vitro and that the chemoattraction is abolished by anti-VEGF neutralizing antibody. rhVEGF (10 ng/mL) induced a mitogenic effect similar to 10% fetal bovine serum (FBS) as assessed by H(3)-thymidine incorporation and elicited 30% decrease in apoptosis as determined by annexin V-fluorescein isothiocyanate (FITC) staining. CONCLUSION: These in vitro studies indicate that (1) tubular epithelial cells chemoattract endothelial cells in a paracrine fashion by secreting VEGF, and (2) VEGF stimulates proliferation and promotes survival of renal epithelial cells in an autocrine manner via VEGFR-2. Taken together, our results suggest that VEGF supports the growth of renal epithelia in addition to mediating kidney vascularization.
BACKGROUND:VEGF secreted by organ parenchymal cells controls vascularization by recruiting endothelial cells and supporting their proliferation. In the developing kidney VEGF-expressing epithelial cells also express VEGF receptors. We showed that VEGF stimulates tubulogenesis in addition to promoting vascularization in metanephric explants. Since explants are grown in serum-free media and are not perfused, we hypothesized that VEGF secreted by renal epithelia may induce their proliferation in an autocrine manner and chemoattract endothelial cells. METHODS: To test these hypotheses, we analyzed VEGF-mediated responses in vitro using several renal epithelial cell lines [immortalized rat proximal tubular cells (IRPT), transformed mouse proximal tubular cells (tsMPT), and normal rat kidney cells (NRK-52E)] expressing VEGF receptors (VEGFR). RESULTS: We demonstrated that VEGFR-2 phosphorylates upon human recombinant VEGF (rhVEGF) exposure, indicating that VEGFR-2 is the signaling receptor. All three cell lines secreted VEGF into the media as indicated by enzyme-linked immunosorbent assay (ELISA) and Western blotting. We showed that these tubular epithelial cells chemoattract endothelial cells when cocultured in vitro and that the chemoattraction is abolished by anti-VEGF neutralizing antibody. rhVEGF (10 ng/mL) induced a mitogenic effect similar to 10% fetal bovine serum (FBS) as assessed by H(3)-thymidine incorporation and elicited 30% decrease in apoptosis as determined by annexin V-fluorescein isothiocyanate (FITC) staining. CONCLUSION: These in vitro studies indicate that (1) tubular epithelial cells chemoattract endothelial cells in a paracrine fashion by secreting VEGF, and (2) VEGF stimulates proliferation and promotes survival of renal epithelial cells in an autocrine manner via VEGFR-2. Taken together, our results suggest that VEGF supports the growth of renal epithelia in addition to mediating kidney vascularization.
Authors: Brian R Hoffmann; Jordan R Wagner; Anthony R Prisco; Agnieszka Janiak; Andrew S Greene Journal: Physiol Genomics Date: 2013-09-10 Impact factor: 3.107
Authors: Xin Zhang; James D Krier; Carolina Amador Carrascal; James F Greenleaf; Behzad Ebrahimi; Ahmad F Hedayat; Stephen C Textor; Amir Lerman; Lilach O Lerman Journal: J Am Soc Nephrol Date: 2016-06-13 Impact factor: 10.121
Authors: Anil Karihaloo; S Ananth Karumanchi; William L Cantley; Shivalingappa Venkatesha; Lloyd G Cantley; Sujata Kale Journal: Mol Cell Biol Date: 2005-09 Impact factor: 4.272