TY - JOUR
T1 - Shear stress stimulates nitric oxide signaling in pulmonary arterial endothelial cells via a reduction in catalase activity
T2 - Role of protein kinase Cδ
AU - Kumar, Sanjiv
AU - Sud, Neetu
AU - Fonseca, Fabio V.
AU - Hou, Yali
AU - Black, Stephen M.
PY - 2010/1
Y1 - 2010/1
N2 - Previous studies have indicated that acute increases in shear stress can stimulate endothelial nitric oxide synthase (eNOS) activity through increased PI3 kinase/Akt signaling and phosphorylation of Ser1177. However, the mechanism by which shear stress activates this pathway has not been adequately resolved nor has the potential role of reactive oxygen species (ROS) been evaluated. Thus, the purpose of this study was to determine if shear-mediated increases in ROS play a role in stimulating Ser1177 phosphorylation and NO signaling in pulmonary arterial endothelial cells (PAEC) exposed to acute increases in shear stress. Our initial studies demonstrated that although shear stress did not increase superoxide levels in PAEC, there was an increase in H2O 2 levels. The increases in H2O2 were associated with a decrease in catalase activity but not protein levels. In addition, we found that acute shear stress caused an increase in eNOS phosphorylation at Ser1177 phosphorylation and a decrease in phosphorylation at Thr495. We also found that the overexpression of catalase significantly attenuated the shear-mediated increases in H2O2, phospho-Ser1177 eNOS, and NO generation. Further investigation identified a decrease in PKCδ activity in response to shear stress, and the overexpression of PKCδ attenuated the shear-mediated decrease in Thr495 phosphorylation and the increase in NO generation, and this led to increased eNOS uncoupling. PKCδ overexpression also attenuated Ser1177 phosphorylation through a posttranslational increase in catalase activity, mediated via a serine phosphorylation event, reducing shear-mediated increases in H2O 2. Together, our data indicate that shear stress decreases PKCδ activity, altering the phosphorylation pattern catalase, leading to decreased catalase activity and increased H2O2 signaling, and this in turn leads to increases in phosphorylation of eNOS at Ser1177 and NO generation. Copyright copy; 2010 the American Physiological Society.
AB - Previous studies have indicated that acute increases in shear stress can stimulate endothelial nitric oxide synthase (eNOS) activity through increased PI3 kinase/Akt signaling and phosphorylation of Ser1177. However, the mechanism by which shear stress activates this pathway has not been adequately resolved nor has the potential role of reactive oxygen species (ROS) been evaluated. Thus, the purpose of this study was to determine if shear-mediated increases in ROS play a role in stimulating Ser1177 phosphorylation and NO signaling in pulmonary arterial endothelial cells (PAEC) exposed to acute increases in shear stress. Our initial studies demonstrated that although shear stress did not increase superoxide levels in PAEC, there was an increase in H2O 2 levels. The increases in H2O2 were associated with a decrease in catalase activity but not protein levels. In addition, we found that acute shear stress caused an increase in eNOS phosphorylation at Ser1177 phosphorylation and a decrease in phosphorylation at Thr495. We also found that the overexpression of catalase significantly attenuated the shear-mediated increases in H2O2, phospho-Ser1177 eNOS, and NO generation. Further investigation identified a decrease in PKCδ activity in response to shear stress, and the overexpression of PKCδ attenuated the shear-mediated decrease in Thr495 phosphorylation and the increase in NO generation, and this led to increased eNOS uncoupling. PKCδ overexpression also attenuated Ser1177 phosphorylation through a posttranslational increase in catalase activity, mediated via a serine phosphorylation event, reducing shear-mediated increases in H2O 2. Together, our data indicate that shear stress decreases PKCδ activity, altering the phosphorylation pattern catalase, leading to decreased catalase activity and increased H2O2 signaling, and this in turn leads to increases in phosphorylation of eNOS at Ser1177 and NO generation. Copyright copy; 2010 the American Physiological Society.
KW - Biomechanical forces
KW - Cell signaling
KW - Endothelial cell
KW - Phosphorylation
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U2 - 10.1152/ajplung.00290.2009
DO - 10.1152/ajplung.00290.2009
M3 - Article
C2 - 19897742
AN - SCOPUS:73549099528
SN - 1040-0605
VL - 298
SP - L105-L116
JO - American Journal of Physiology - Lung Cellular and Molecular Physiology
JF - American Journal of Physiology - Lung Cellular and Molecular Physiology
IS - 1
ER -