John Kanellis - Academia.edu (original) (raw)

Papers by John Kanellis

Kidney International, 2000

kidney may have evolved unique patterns of VEGF regulation Redistribution of cytoplasmic VEGF to ... more kidney may have evolved unique patterns of VEGF regulation Redistribution of cytoplasmic VEGF to the basolateral aspect to cope with acute hypoxia. of renal tubular cells in ischemia-reperfusion injury. Background. Vascular endothelial growth factor (VEGF) mRNA and protein expression are increased by hypoxia in a variety of cell types and organs. In the kidney, however, chronic Vascular endothelial growth factor (VEGF) is a potent hypoxia does not up-regulate VEGF mRNA. This suggests that endothelial cell mitogen that promotes angiogenesis, in-VEGF may be regulated by unique mechanisms in the kidney. Methods. Unilateral ischemia was induced in rats by vascular creases vascular permeability, and is chemotactic for cross-clamping (40 min) followed by reperfusion (0, 20, 40, and monocytes [reviewed in 1, 2]. It has potential roles in a 80 min). The distribution of VEGF protein was determined wide variety of situations, including embryogenesis, tuby immunohistochemical staining and Western blotting. mRNA mor growth, diabetes, inflammatory responses, and tiswas detected by Northern blotting and semiquantitative resue remodeling [1-8]. Recently, it has also been reported verse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical staining for VEGF was verified using two that VEGF inhibits apoptosis in endothelial cells [9, 10]. VEGF antibodies. To further substantiate the immunohisto-There are three isoforms of VEGF in the rat (VEGF 120 , chemical findings, laser scanning confocal fluorescence micros-VEGF 164 , and VEGF 188), arising from alternative splicing copy was used to demonstrate the distribution of VEGF protein of mRNA. Monomers are joined by disulfide bonds to in rat renal tubular epithelial cells (NRK52-E) subjected to hypoxia (40 min) and re-oxygenation (0, 5, 20, 40 and 80 min). form homodimers. The relative abundance of each iso-Results. Normal kidneys showed diffuse immunohistochemform varies depending on the organ. In the rat kidney, ical staining for VEGF in all tubules of the renal cortex and VEGF 164 mRNA is the most abundant species, with medulla. Following ischemia, staining demonstrated a promi-VEGF 188 mRNA being the least abundant [11]. Specific nent shift of cytoplasmic VEGF to the basolateral aspect of biological characteristics, such as mitogenic activity, bindtubular cells with both VEGF antibodies. The distribution of cytoplasmic VEGF returned to normal following 40 and 80 mining to heparan sulfate proteoglycans (HSPGs), and seutes of reperfusion. Western blots of cytoplasmic samples from cretion, differ markedly between isoforms, suggesting ischemic kidneys reperfused for 0 and 20 minutes showed deunique roles for each [12-15]. creased levels of VEGF 164 compared with normal (P Ͻ 0.01). Studies performed in vitro have demonstrated similar-VEGF 164 and VEGF 188 levels in the membrane fraction showed no change. Northern blots and semiquantitative RT-PCR showed ities between the regulation of VEGF and erythropoietin no significant up-regulation of VEGF mRNA or change in the (EPO). The expression of VEGF mRNA has been shown splice pattern. NRK52-E cells subjected to hypoxia and reto be markedly increased in a variety of cells when they oxygenation for 0 and 5 minutes showed increased staining for are made hypoxic or when hypoxia-mimicking tech-VEGF compared with normal, with prominent VEGF staining niques are used, such as incubation with divalent cations at the periphery of the cell, similar to the appearance in ischemic kidneys. VEGF staining became more diffuse with further (for example, cobalt chloride) [16-22]. Evidence suggests re-oxygenation. that this occurs via the activation of a heme-containing, Conclusion. Although synthesis of VEGF mRNA and prooxygen-sensing receptor, which ultimately leads to the tein is not increased during ischemia reperfusion injury, preinduction of the transcription factor hypoxia-inducible existing VEGF in the tubular cell cytoplasm redistributes to the basolateral aspect of the cells. These data suggest that the factor-1 (HIF-1) [23]. Studies performed in vivo have also shown that VEGF mRNA increases in response to hypoxia [21, 24-26], although this has not been reported

Kidney International, 2000

kidney may have evolved unique patterns of VEGF regulation Redistribution of cytoplasmic VEGF to ... more kidney may have evolved unique patterns of VEGF regulation Redistribution of cytoplasmic VEGF to the basolateral aspect to cope with acute hypoxia. of renal tubular cells in ischemia-reperfusion injury. Background. Vascular endothelial growth factor (VEGF) mRNA and protein expression are increased by hypoxia in a variety of cell types and organs. In the kidney, however, chronic Vascular endothelial growth factor (VEGF) is a potent hypoxia does not up-regulate VEGF mRNA. This suggests that endothelial cell mitogen that promotes angiogenesis, in-VEGF may be regulated by unique mechanisms in the kidney. Methods. Unilateral ischemia was induced in rats by vascular creases vascular permeability, and is chemotactic for cross-clamping (40 min) followed by reperfusion (0, 20, 40, and monocytes [reviewed in 1, 2]. It has potential roles in a 80 min). The distribution of VEGF protein was determined wide variety of situations, including embryogenesis, tuby immunohistochemical staining and Western blotting. mRNA mor growth, diabetes, inflammatory responses, and tiswas detected by Northern blotting and semiquantitative resue remodeling [1-8]. Recently, it has also been reported verse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical staining for VEGF was verified using two that VEGF inhibits apoptosis in endothelial cells [9, 10]. VEGF antibodies. To further substantiate the immunohisto-There are three isoforms of VEGF in the rat (VEGF 120 , chemical findings, laser scanning confocal fluorescence micros-VEGF 164 , and VEGF 188), arising from alternative splicing copy was used to demonstrate the distribution of VEGF protein of mRNA. Monomers are joined by disulfide bonds to in rat renal tubular epithelial cells (NRK52-E) subjected to hypoxia (40 min) and re-oxygenation (0, 5, 20, 40 and 80 min). form homodimers. The relative abundance of each iso-Results. Normal kidneys showed diffuse immunohistochemform varies depending on the organ. In the rat kidney, ical staining for VEGF in all tubules of the renal cortex and VEGF 164 mRNA is the most abundant species, with medulla. Following ischemia, staining demonstrated a promi-VEGF 188 mRNA being the least abundant [11]. Specific nent shift of cytoplasmic VEGF to the basolateral aspect of biological characteristics, such as mitogenic activity, bindtubular cells with both VEGF antibodies. The distribution of cytoplasmic VEGF returned to normal following 40 and 80 mining to heparan sulfate proteoglycans (HSPGs), and seutes of reperfusion. Western blots of cytoplasmic samples from cretion, differ markedly between isoforms, suggesting ischemic kidneys reperfused for 0 and 20 minutes showed deunique roles for each [12-15]. creased levels of VEGF 164 compared with normal (P Ͻ 0.01). Studies performed in vitro have demonstrated similar-VEGF 164 and VEGF 188 levels in the membrane fraction showed no change. Northern blots and semiquantitative RT-PCR showed ities between the regulation of VEGF and erythropoietin no significant up-regulation of VEGF mRNA or change in the (EPO). The expression of VEGF mRNA has been shown splice pattern. NRK52-E cells subjected to hypoxia and reto be markedly increased in a variety of cells when they oxygenation for 0 and 5 minutes showed increased staining for are made hypoxic or when hypoxia-mimicking tech-VEGF compared with normal, with prominent VEGF staining niques are used, such as incubation with divalent cations at the periphery of the cell, similar to the appearance in ischemic kidneys. VEGF staining became more diffuse with further (for example, cobalt chloride) [16-22]. Evidence suggests re-oxygenation. that this occurs via the activation of a heme-containing, Conclusion. Although synthesis of VEGF mRNA and prooxygen-sensing receptor, which ultimately leads to the tein is not increased during ischemia reperfusion injury, preinduction of the transcription factor hypoxia-inducible existing VEGF in the tubular cell cytoplasm redistributes to the basolateral aspect of the cells. These data suggest that the factor-1 (HIF-1) [23]. Studies performed in vivo have also shown that VEGF mRNA increases in response to hypoxia [21, 24-26], although this has not been reported