Vascular Endothelial Growth Factor Has Neurotrophic Activity and Stimulates Axonal Outgrowth, Enhancing Cell Survival and Schwann Cell Proliferation in the Peripheral Nervous System

“The samples were electrophoresed according to Laemmli (1970).”

“Both receptor types are essential for development and organization of endothelial cells and the disruption of the genes encoding flk-1 and flt-1 results in defects of blood vessel formation and an early death of homozygous mice embryo (Fong et al., 1995; Shalaby et al., 1995 ).”

“Both receptor types are essential for development and organization of endothelial cells and the disruption of the genes encoding flk-1 and flt-1 results in defects of blood vessel formation and an early death of homozygous mice embryo (Fong et al., 1995; Shalaby et al., 1995).”

“It has also been reported that VEGF165 binds to neurophilin-1 ( Soker et al., 1998 ), a neuronal cell surface molecule that is important for chemorepulsive signaling during peripheral axonal outgrowth in the developing mice (Kitsukawa et al., 1997).”

“However, other angiogenic factors, including basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF), have been shown to be neurotrophic or exert growthpromoting activity (Rydel and Greene, 1987; Davis and Stroobant, 1990; Smits et al., 1991; Fujimoto et al., 1997).”

“VEGF exerts its action via high-affinity binding to two types of phosphotyrosine kinase receptors: fms-like tyrosine kinase (flt-1) and fetal liver kinase receptor (flk-1) (De Vries et al., 1992; Quinn et al., 1993).”

“The human counterpart to the flk-1 receptor, which activates the mitogen-activated protein kinase (MAPK) pathway, is also known to induce reorganization of actin filaments, chemotaxis, and give rise to a mitogen response in endothelial cells (Waltenberger et al., 1994; Kroll and Waltenberger, 1997).”

“In the nervous system, VEGF mRNA has been found in neurons in the capillary-rich areas of the brain, for instance in the pars distalis cells of the pituitary gland but also in glial cells in the retina after hypoxia (Ferrara et al., 1992; Stone et al., 1995).”

“, in the range of the Kd for the flk-1 receptor (Terman et al., 1992; Waltenberger et al., 1994).”

“…DRG; growth factor; mouse; nerve regeneration; peripheral nerve; SCG; VEGF Vascular endothelial growth factor (VEGF) is a potent and presumed selective endothelial cell mitogen that promotes angiogenesis but also increases blood vessel permeability (for review, see Ferrara and Davis-Smyth, 1997).”

“In the nervous system, VEGF mRNA has been found in neurons in the capillary-rich areas of the brain, for instance in the pars distalis cells of the pituitary gland but also in glial cells in the retina after hypoxia (Ferrara et al., 1992; Stone et al., 1995).”

“VEGF is expressed in epithelial cells of various capillary-rich tissues and is also found in activated macrophages and in tumors (Berse et al., 1992).”

“One possibility is that VEGF has a role similar to that observed for brain-derived neurotrophic factor, which in DRG has been suggested to be an autocrine survival factor (Acheson et al., 1995).”

“VEGF exerts its action via high-affinity binding to two types of phosphotyrosine kinase receptors: fms-like tyrosine kinase (flt-1) and fetal liver kinase receptor (flk-1) (De Vries et al., 1992; Quinn et al., 1993).”

“It has also been reported that VEGF165 binds to neurophilin-1 (Soker et al., 1998), a neuronal cell surface molecule that is important for chemorepulsive signaling during peripheral axonal outgrowth in the developing mice ( Kitsukawa et al., 1997 ).”

“Such a cellular distribution is characteristic also for neurons that express the high-affinity NGF (TrkA) receptor and calcitonin generelated peptide (Averill et al., 1995; Fagan et al., 1996).”

“So far, five isoforms have been isolated in humans, VEGF 206, 189, 165, 145, and 121 (Ferrara and Davis-Smyth, 1997; Poltorak et al., 1997) and in murines, four different forms have been found, VEGF 188, 164, 120, and 115 (Breier et al., 1992; Sugihara et al., 1998).”

“However, neither neurons nor glial cells appear to possess the flt-1 receptor (Peters et al., 1993).”

“Explants of SCG and DRG were used for studies of axonal outgrowth (Levi-Montalcini et al., 1954; Fenton, 1970; Tonge et al., 1998).”

“The human counterpart to the flk-1 receptor, which activates the mitogen-activated protein kinase (MAPK) pathway, is also known to induce reorganization of actin filaments, chemotaxis, and give rise to a mitogen response in endothelial cells (Waltenberger et al., 1994; Kroll and Waltenberger, 1997).”

“Such a dose–response has also been noted for other growth factors, including bFGF and NGF, acting on PC12 cells or DRG neurons (Rydel and Greene, 1987; Conti et al., 1997; Rutishauser and Edelman, 1980).”

“The method for staining of the Golgi apparatus was based on a procedure developed by Lipsky and Pagano (1985).”

“However, other angiogenic factors, including basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF), have been shown to be neurotrophic or exert growthpromoting activity (Rydel and Greene, 1987; Davis and Stroobant, 1990; Smits et al., 1991; Fujimoto et al., 1997).”

“S-100 is a glial cell protein (Hydén and McEwen, 1966; Li et al., 1997).”

“However, other angiogenic factors, including basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF), have been shown to be neurotrophic or exert growthpromoting activity (Rydel and Greene, 1987; Davis and Stroobant, 1990; Smits et al., 1991; Fujimoto et al., 1997).”

“Such a cellular distribution is characteristic also for neurons that express the high-affinity NGF (TrkA) receptor and calcitonin generelated peptide (Averill et al., 1995; Fagan et al., 1996).”

“Explants of SCG and DRG were used for studies of axonal outgrowth (Levi-Montalcini et al., 1954; Fenton, 1970; Tonge et al., 1998).”

“At least four different isoforms of VEGF have been found in murines, and in rat brain VEGF164 dominates (Bacic et al., 1995).”

“Such reciprocal cell–cell interaction has been reported for NT-3/neuregulin, acting on sympathetic neuroblasts and non-neuronal cells (Verdi et al., 1996).”

“BrdU labeling was used to visualize the presence of proliferating cells in cultured SCG and DRG. BrdU is a thymidine analog that is incorporated into DNA of cells in the S-phase (Moran et al., 1985).”

“The protein kinase inhibitor K252a at a concentration (50 nM) that inhibited trk tyrosine kinases ( Ohmichi et al., 1992 ) and effectively suppressed NGF induced axonal outgrowth (data not shown) did not affect the VEGF-induced axonal outgrowth (Fig. 10).”

“Such a dose–response has also been noted for other growth factors, including bFGF and NGF, acting on PC12 cells or DRG neurons (Rydel and Greene, 1987; Conti et al., 1997; Rutishauser and Edelman, 1980).”

“Furthermore, VEGF expression is induced in astrocytes at the site of a spinal cord injury (Bartholdi et al., 1997).”

“However, other angiogenic factors, including basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF), have been shown to be neurotrophic or exert growthpromoting activity (Rydel and Greene, 1987; Davis and Stroobant, 1990; Smits et al., 1991; Fujimoto et al., 1997).”

“Such a dose–response has also been noted for other growth factors, including bFGF and NGF, acting on PC12 cells or DRG neurons (Rydel and Greene, 1987; Conti et al., 1997; Rutishauser and Edelman, 1980).”

“A modified method for terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) was used to evaluate cell survival (Ekström, 1995).”

“On the other hand, VEGF treatment promoted survival of both neurons and satellite/Schwann cells in the adult ganglia, which NGF does not (Edström et al., 1996; our unpublished observations).”

“, 1997) and in murines, four different forms have been found, VEGF 188, 164, 120, and 115 (Breier et al., 1992; Sugihara et al., 1998).”

“Explants of SCG and DRG were used for studies of axonal outgrowth (Levi-Montalcini et al., 1954; Fenton, 1970; Tonge et al., 1998).”

“The slides were processed for BrdU and S-100 double labeling as previously described (Sondell et al., 1997).”