TY - JOUR
T1 - Modulation of PKCδ signaling alters the shear stress-mediated increases in endothelial nitric oxide synthase transcription
T2 - Role of STAT3
AU - Sud, Neetu
AU - Kumar, Sanjiv
AU - Wedgwood, Stephen
AU - Black, Stephen M.
PY - 2009/3
Y1 - 2009/3
N2 - We have previously shown that the regulation of endothelial nitric oxide synthase (eNOS) in endothelial cells isolated from fetal lamb under static conditions is positively regulated by PKCδ. In this study, we explore the role of PKCδ in regulating shear-induced upregulation of eNOS. We found that shear caused a decrease in PKCδ activation. Modulation of PKCδ before shear with a dominant negative mutant of PKCδ (DN PKCδ) or bryostatin (a known PKCδ activator) demonstrated that PKCδ inhibition potentiates the shear-mediated increases in eNOS expression and activity, while PKCδ activation inhibited these events. To gain insight into the mechanism by which PKCδ inhibits shear-induced eNOS expression, we examined activation of STAT3, a known target for PKCδ phosphorylation. We found that shear decreased the phosphorylation of STAT3. Further the transfection of cells with DN PKCδ reduced, while PKCδ activation enhanced, STAT3 phosphorylation in the presence of shear. Transfection of cells with a dominant negative mutant of STAT3 enhanced eNOS promoter activity and nitric oxide production in response to shear. Finally, we found that mutating the STAT3 binding site sequence within the eNOS promoter increased promoter activity in response to shear and that this was no longer inhibited by bryostatin. In conclusion, shear decreases PKCδ activity and, subsequently, reduces STAT3 binding to the eNOS promoter. This signaling pathway plays a previously unidentified role in the regulation of eNOS expression by shear stress.
AB - We have previously shown that the regulation of endothelial nitric oxide synthase (eNOS) in endothelial cells isolated from fetal lamb under static conditions is positively regulated by PKCδ. In this study, we explore the role of PKCδ in regulating shear-induced upregulation of eNOS. We found that shear caused a decrease in PKCδ activation. Modulation of PKCδ before shear with a dominant negative mutant of PKCδ (DN PKCδ) or bryostatin (a known PKCδ activator) demonstrated that PKCδ inhibition potentiates the shear-mediated increases in eNOS expression and activity, while PKCδ activation inhibited these events. To gain insight into the mechanism by which PKCδ inhibits shear-induced eNOS expression, we examined activation of STAT3, a known target for PKCδ phosphorylation. We found that shear decreased the phosphorylation of STAT3. Further the transfection of cells with DN PKCδ reduced, while PKCδ activation enhanced, STAT3 phosphorylation in the presence of shear. Transfection of cells with a dominant negative mutant of STAT3 enhanced eNOS promoter activity and nitric oxide production in response to shear. Finally, we found that mutating the STAT3 binding site sequence within the eNOS promoter increased promoter activity in response to shear and that this was no longer inhibited by bryostatin. In conclusion, shear decreases PKCδ activity and, subsequently, reduces STAT3 binding to the eNOS promoter. This signaling pathway plays a previously unidentified role in the regulation of eNOS expression by shear stress.
KW - Biomechanical forces
KW - Cell signaling
KW - Endothelial cell
KW - Phosphorylation
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U2 - 10.1152/ajplung.90534.2008
DO - 10.1152/ajplung.90534.2008
M3 - Article
C2 - 19118090
AN - SCOPUS:64249170535
SN - 1040-0605
VL - 296
SP - L519-L526
JO - American Journal of Physiology - Lung Cellular and Molecular Physiology
JF - American Journal of Physiology - Lung Cellular and Molecular Physiology
IS - 3
ER -