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Viswanathan Natarajan - One of the best experts on this subject based on the ideXlab platform.
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Role of Sphingosine Kinase 1 and S1P Transporter Spns2 in HGF-mediated Lamellipodia Formation in Lung Endothelium
Journal of Biological Chemistry, 2016Co-Authors: David L. Ebenezer, Evgeny Berdyshev, Irina Bronova, Mark Shaaya, Anantha Harijith, Viswanathan NatarajanAbstract:Hepatocyte growth factor (HGF) signaling via c-Met is known to promote endothelial cell motility and angiogenesis. We have previously reported that HGF stimulates lamellipodia formation and motility of human Lung microvascular endothelial cells (HLMVECs) via PI3K/Akt signal transduction and reactive oxygen species generation. Here, we report a role for HGF-induced intracellular sphingosine-1-phosphate (S1P) generation catalyzed by sphingosine kinase 1 (SphK1), S1P transporter, spinster homolog 2 (Spns2), and S1P receptor, S1P1, in lamellipodia formation and perhaps motility of HLMVECs. HGF stimulated SphK1 phosphorylation and enhanced intracellular S1P levels in HLMVECs, which was blocked by inhibition of SphK1. HGF enhanced co-localization of SphK1/p-SphK1 with actin/cortactin in lamellipodia and down-regulation or inhibition of SphK1 attenuated HGF-induced lamellipodia formation in HLMVECs. In addition, down-regulation of Spns2 also suppressed HGF-induced lamellipodia formation, suggesting a key role for inside-out S1P signaling. The HGF-mediated phosphorylation of SphK1 and its localization in lamellipodia was dependent on c-Met and ERK1/2 signaling, but not the PI3K/Akt pathway; however, blocking PI3K/Akt signaling attenuated HGF-mediated phosphorylation of Spns2. Down-regulation of S1P1, but not S1P2 or S1P3, with specific siRNA attenuated HGF-induced lamellipodia formation. Further, HGF enhanced association of Spns2 with S1P1 that was blocked by inhibiting SphK1 activity with PF-543. Moreover, HGF-induced migration of HLMVECs was attenuated by down-regulation of Spns2. Taken together, these results suggest that HGF/c-Met-mediated lamellipodia formation, and perhaps motility is dependent on intracellular generation of S1P via activation and localization of SphK1 to cell periphery and Spns2-mediated extracellular transportation of S1P and its inside-out signaling via S1P1.
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hyperoxia induced p47phox activation and ros generation is mediated through s1p transporter spns2 and s1p s1p1 2 signaling axis in Lung Endothelium
American Journal of Physiology-lung Cellular and Molecular Physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad Kanteti, Viswanathan NatarajanAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
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Nrf2 regulates hyperoxia-induced Nox4 expression in human Lung Endothelium: Identification of functional antioxidant response elements on the Nox4 promoter
Free Radical Biology and Medicine, 2011Co-Authors: Srikanth Pendyala, Jaideep Moitra, Satish Kalari, Steven R. Kleeberger, Yutong Zhao, Sekhar P. Reddy, Joe G.n. Garcia, Viswanathan NatarajanAbstract:Abstract Reactive oxygen species (ROS) generated by vascular endothelial and smooth muscle cells contribute to the development and progression of vascular diseases. We have recently shown that hyperoxia enhances NADPH oxidase 4 (Nox4) expression, which regulates Lung endothelial cell migration and angiogenesis. Regulation of Nox4 in the vasculature is poorly understood. The objective of this study was to identify the transcriptional factor(s) involved in regulation of endothelial Nox4. We found that hyperoxia-induced Nox4 expression was markedly reduced in Nrf2−/− mice, compared to Nrf2+/+ mice. Exposure of human Lung microvascular endothelial cells (HLMVECs) to hyperoxia stimulated Nrf2 translocation from the cytoplasm to the nucleus and increased Nox4 expression. Knockdown of Nrf2 expression using an siRNA approach attenuated basal Nox4 expression; however, it enhanced superoxide/ROS generation under both normoxia and hyperoxia. In silico analysis revealed the presence of at least three consensus sequences for the antioxidant response element (ARE) in the promoter region of Nox4. In transient transfections, hyperoxia stimulated Nox4 promoter activity in HLMVECs, and deletion of the − 438 to − 458 and − 619 to − 636 sequences markedly reduced hyperoxia-stimulated Nox4 promoter activation. ChIP analysis revealed an enhanced recruitment of Nrf2 to the endogenous Nox4 promoter spanning these two AREs after hyperoxic insult. Collectively, these results demonstrate, for the first time, a novel role for Nrf2 in regulating hyperoxia-induced Nox4 transcription via AREs in Lung Endothelium.
Anantha Harijith - One of the best experts on this subject based on the ideXlab platform.
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Role of Sphingosine Kinase 1 and S1P Transporter Spns2 in HGF-mediated Lamellipodia Formation in Lung Endothelium
Journal of Biological Chemistry, 2016Co-Authors: David L. Ebenezer, Evgeny Berdyshev, Irina Bronova, Mark Shaaya, Anantha Harijith, Viswanathan NatarajanAbstract:Hepatocyte growth factor (HGF) signaling via c-Met is known to promote endothelial cell motility and angiogenesis. We have previously reported that HGF stimulates lamellipodia formation and motility of human Lung microvascular endothelial cells (HLMVECs) via PI3K/Akt signal transduction and reactive oxygen species generation. Here, we report a role for HGF-induced intracellular sphingosine-1-phosphate (S1P) generation catalyzed by sphingosine kinase 1 (SphK1), S1P transporter, spinster homolog 2 (Spns2), and S1P receptor, S1P1, in lamellipodia formation and perhaps motility of HLMVECs. HGF stimulated SphK1 phosphorylation and enhanced intracellular S1P levels in HLMVECs, which was blocked by inhibition of SphK1. HGF enhanced co-localization of SphK1/p-SphK1 with actin/cortactin in lamellipodia and down-regulation or inhibition of SphK1 attenuated HGF-induced lamellipodia formation in HLMVECs. In addition, down-regulation of Spns2 also suppressed HGF-induced lamellipodia formation, suggesting a key role for inside-out S1P signaling. The HGF-mediated phosphorylation of SphK1 and its localization in lamellipodia was dependent on c-Met and ERK1/2 signaling, but not the PI3K/Akt pathway; however, blocking PI3K/Akt signaling attenuated HGF-mediated phosphorylation of Spns2. Down-regulation of S1P1, but not S1P2 or S1P3, with specific siRNA attenuated HGF-induced lamellipodia formation. Further, HGF enhanced association of Spns2 with S1P1 that was blocked by inhibiting SphK1 activity with PF-543. Moreover, HGF-induced migration of HLMVECs was attenuated by down-regulation of Spns2. Taken together, these results suggest that HGF/c-Met-mediated lamellipodia formation, and perhaps motility is dependent on intracellular generation of S1P via activation and localization of SphK1 to cell periphery and Spns2-mediated extracellular transportation of S1P and its inside-out signaling via S1P1.
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hyperoxia induced p47phox activation and ros generation is mediated through s1p transporter spns2 and s1p s1p1 2 signaling axis in Lung Endothelium
American Journal of Physiology-lung Cellular and Molecular Physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad Kanteti, Viswanathan NatarajanAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
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Hyperoxia-induced p47phox activation and ROS generation is mediated through S1P transporter Spns2, and S1P/S1P1&2 signaling axis in Lung Endothelium
American journal of physiology. Lung cellular and molecular physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad KantetiAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
David L. Ebenezer - One of the best experts on this subject based on the ideXlab platform.
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Role of Sphingosine Kinase 1 and S1P Transporter Spns2 in HGF-mediated Lamellipodia Formation in Lung Endothelium
Journal of Biological Chemistry, 2016Co-Authors: David L. Ebenezer, Evgeny Berdyshev, Irina Bronova, Mark Shaaya, Anantha Harijith, Viswanathan NatarajanAbstract:Hepatocyte growth factor (HGF) signaling via c-Met is known to promote endothelial cell motility and angiogenesis. We have previously reported that HGF stimulates lamellipodia formation and motility of human Lung microvascular endothelial cells (HLMVECs) via PI3K/Akt signal transduction and reactive oxygen species generation. Here, we report a role for HGF-induced intracellular sphingosine-1-phosphate (S1P) generation catalyzed by sphingosine kinase 1 (SphK1), S1P transporter, spinster homolog 2 (Spns2), and S1P receptor, S1P1, in lamellipodia formation and perhaps motility of HLMVECs. HGF stimulated SphK1 phosphorylation and enhanced intracellular S1P levels in HLMVECs, which was blocked by inhibition of SphK1. HGF enhanced co-localization of SphK1/p-SphK1 with actin/cortactin in lamellipodia and down-regulation or inhibition of SphK1 attenuated HGF-induced lamellipodia formation in HLMVECs. In addition, down-regulation of Spns2 also suppressed HGF-induced lamellipodia formation, suggesting a key role for inside-out S1P signaling. The HGF-mediated phosphorylation of SphK1 and its localization in lamellipodia was dependent on c-Met and ERK1/2 signaling, but not the PI3K/Akt pathway; however, blocking PI3K/Akt signaling attenuated HGF-mediated phosphorylation of Spns2. Down-regulation of S1P1, but not S1P2 or S1P3, with specific siRNA attenuated HGF-induced lamellipodia formation. Further, HGF enhanced association of Spns2 with S1P1 that was blocked by inhibiting SphK1 activity with PF-543. Moreover, HGF-induced migration of HLMVECs was attenuated by down-regulation of Spns2. Taken together, these results suggest that HGF/c-Met-mediated lamellipodia formation, and perhaps motility is dependent on intracellular generation of S1P via activation and localization of SphK1 to cell periphery and Spns2-mediated extracellular transportation of S1P and its inside-out signaling via S1P1.
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hyperoxia induced p47phox activation and ros generation is mediated through s1p transporter spns2 and s1p s1p1 2 signaling axis in Lung Endothelium
American Journal of Physiology-lung Cellular and Molecular Physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad Kanteti, Viswanathan NatarajanAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
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Hyperoxia-induced p47phox activation and ROS generation is mediated through S1P transporter Spns2, and S1P/S1P1&2 signaling axis in Lung Endothelium
American journal of physiology. Lung cellular and molecular physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad KantetiAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
Prasad Kanteti - One of the best experts on this subject based on the ideXlab platform.
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hyperoxia induced p47phox activation and ros generation is mediated through s1p transporter spns2 and s1p s1p1 2 signaling axis in Lung Endothelium
American Journal of Physiology-lung Cellular and Molecular Physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad Kanteti, Viswanathan NatarajanAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
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Hyperoxia-induced p47phox activation and ROS generation is mediated through S1P transporter Spns2, and S1P/S1P1&2 signaling axis in Lung Endothelium
American journal of physiology. Lung cellular and molecular physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad KantetiAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
Evgeny Berdyshev - One of the best experts on this subject based on the ideXlab platform.
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Role of Sphingosine Kinase 1 and S1P Transporter Spns2 in HGF-mediated Lamellipodia Formation in Lung Endothelium
Journal of Biological Chemistry, 2016Co-Authors: David L. Ebenezer, Evgeny Berdyshev, Irina Bronova, Mark Shaaya, Anantha Harijith, Viswanathan NatarajanAbstract:Hepatocyte growth factor (HGF) signaling via c-Met is known to promote endothelial cell motility and angiogenesis. We have previously reported that HGF stimulates lamellipodia formation and motility of human Lung microvascular endothelial cells (HLMVECs) via PI3K/Akt signal transduction and reactive oxygen species generation. Here, we report a role for HGF-induced intracellular sphingosine-1-phosphate (S1P) generation catalyzed by sphingosine kinase 1 (SphK1), S1P transporter, spinster homolog 2 (Spns2), and S1P receptor, S1P1, in lamellipodia formation and perhaps motility of HLMVECs. HGF stimulated SphK1 phosphorylation and enhanced intracellular S1P levels in HLMVECs, which was blocked by inhibition of SphK1. HGF enhanced co-localization of SphK1/p-SphK1 with actin/cortactin in lamellipodia and down-regulation or inhibition of SphK1 attenuated HGF-induced lamellipodia formation in HLMVECs. In addition, down-regulation of Spns2 also suppressed HGF-induced lamellipodia formation, suggesting a key role for inside-out S1P signaling. The HGF-mediated phosphorylation of SphK1 and its localization in lamellipodia was dependent on c-Met and ERK1/2 signaling, but not the PI3K/Akt pathway; however, blocking PI3K/Akt signaling attenuated HGF-mediated phosphorylation of Spns2. Down-regulation of S1P1, but not S1P2 or S1P3, with specific siRNA attenuated HGF-induced lamellipodia formation. Further, HGF enhanced association of Spns2 with S1P1 that was blocked by inhibiting SphK1 activity with PF-543. Moreover, HGF-induced migration of HLMVECs was attenuated by down-regulation of Spns2. Taken together, these results suggest that HGF/c-Met-mediated lamellipodia formation, and perhaps motility is dependent on intracellular generation of S1P via activation and localization of SphK1 to cell periphery and Spns2-mediated extracellular transportation of S1P and its inside-out signaling via S1P1.
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hyperoxia induced p47phox activation and ros generation is mediated through s1p transporter spns2 and s1p s1p1 2 signaling axis in Lung Endothelium
American Journal of Physiology-lung Cellular and Molecular Physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad Kanteti, Viswanathan NatarajanAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
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Hyperoxia-induced p47phox activation and ROS generation is mediated through S1P transporter Spns2, and S1P/S1P1&2 signaling axis in Lung Endothelium
American journal of physiology. Lung cellular and molecular physiology, 2016Co-Authors: Anantha Harijith, David L. Ebenezer, Evgeny Berdyshev, Srikanth Pendyala, Yue-ting Wang, Peter T. Toth, Prasad KantetiAbstract:Hyperoxia-induced Lung injury adversely affects ICU patients and neonates on ventilator assisted breathing. The underlying culprit appears to be reactive oxygen species (ROS)-induced Lung damage. The major contributor of hyperoxia-induced ROS is activation of the multiprotein enzyme complex NADPH oxidase. Sphingosine-1-phosphate (S1P) signaling is known to be involved in hyperoxia-mediated ROS generation; however, the mechanism(s) of S1P-induced NADPH oxidase activation is unclear. Here, we investigated various steps in the S1P signaling pathway mediating ROS production in response to hyperoxia in Lung Endothelium. Of the two closely related sphingosine kinases (SphKs)1 and 2, which synthesize S1P from sphingosine, only Sphk1(-/-) mice conferred protection against hyperoxia-induced Lung injury. S1P is metabolized predominantly by S1P lyase and partial deletion of Sgpl1 (Sgpl1(+/-)) in mice accentuated Lung injury. Hyperoxia stimulated S1P accumulation in human Lung microvascular endothelial cells (HLMVECs), and downregulation of S1P transporter spinster homolog 2 (Spns2) or S1P receptors S1P1&2, but not S1P3, using specific siRNA attenuated hyperoxia-induced p47(phox) translocation to cell periphery and ROS generation in HLMVECs. These results suggest a role for Spns2 and S1P1&2 in hyperoxia-mediated ROS generation. In addition, p47(phox) (phox:phagocyte oxidase) activation and ROS generation was also reduced by PF543, a specific SphK1 inhibitor in HLMVECs. Our data indicate a novel role for Spns2 and S1P1&2 in the activation of p47(phox) and production of ROS involved in hyperoxia-mediated Lung injury in neonatal and adult mice.
