Abstract
We previously demonstrated that lysophosphatidylcholine up-regulated endothelial nitric-oxide synthase promoter activity by increasing Sp1 binding via the action of protein serine/threonine phosphatase 2A (Cieslik, K., Zembowicz, A., Tang, J.-L., and Wu, K.K. (1998) J. Biol. Chem. 273, 14885-14890). To characterize the regulation of basal endothelial nitric-oxide synthase promoter activity and the signaling pathway through which lysophosphatidylcholine augments endothelial nitric-oxide synthase transcription, we used a casein kinase 2 inhibitor coupled with immunoprecipitation to demonstrate that basal Sp1 binding and endothelial nitric-oxide synthase promoter activity were controlled by casein kinase 2 complexed with protein serine/threonine phosphatase 2A. Casein kinase 2 catalyzed protein serine/threonine phosphatase 2A phosphorylation thereby inhibiting its activity. Lysophosphatidylcholine selectively activated p42/p44 mitogen-activated protein kinase. Purified extracellular regulated kinase 2 blocked casein kinase 2 activity and increased protein serine/threonine phosphatase 2A activity, resulting in an increased Sp1 binding and endothelial nitric-oxide synthase promoter activity. These results indicate that Sp1 binding to its cognate site on the endothelial nitric-oxide synthase promoter and its transactivation of endothelial nitric-oxide synthase is regulated by post-translational Sp1 phosphorylation and dephosphorylation through a dynamic interaction between casein kinase 2 and protein serine/threonine phosphatase 2A.
Highlights
We previously demonstrated that lysophosphatidylcholine up-regulated endothelial nitric-oxide synthase promoter activity by increasing Sp1 binding via the action of protein serine/threonine phosphatase 2A (Cieslik, K., Zembowicz, A., Tang, J.-L., and Wu, K.K. (1998) J
Our work demonstrated that lysoPC-induced increase in Sp1 binding activity was blocked by okadaic acid and correlated with an elevated PP2A activity [15], suggesting that Endothelial nitric-oxide synthase (eNOS) transcription is regulated by post-translational modification of Sp1 via the actions of PP2A and a nuclear kinase, which was recently identified as casein kinase 2 (CK2) [16]
Control of Sp1 Binding and eNOS Promoter Activity by CK2—In our previous report [15], we showed by using luciferase reporter constructs that Sp1 sites at Ϫ104 and Ϫ90 of eNOS promoter region were essential for eNOS promoter activity
Summary
We previously demonstrated that lysophosphatidylcholine up-regulated endothelial nitric-oxide synthase promoter activity by increasing Sp1 binding via the action of protein serine/threonine phosphatase 2A (Cieslik, K., Zembowicz, A., Tang, J.-L., and Wu, K.K. (1998) J. We previously demonstrated that lysophosphatidylcholine up-regulated endothelial nitric-oxide synthase promoter activity by increasing Sp1 binding via the action of protein serine/threonine phosphatase 2A Purified extracellular regulated kinase 2 blocked casein kinase 2 activity and increased protein serine/threonine phosphatase 2A activity, resulting in an increased Sp1 binding and endothelial nitric-oxide synthase promoter activity. Our work demonstrated that lysoPC-induced increase in Sp1 binding activity was blocked by okadaic acid and correlated with an elevated PP2A activity [15], suggesting that eNOS transcription is regulated by post-translational modification of Sp1 via the actions of PP2A and a nuclear kinase, which was recently identified as casein kinase 2 (CK2) [16]. LysoPC activates selectively the extracellular signalregulated kinase (ERK-1 and ERK-2), which suppresses the CK2 activity and unleashes its inhibition of PP2A, leading to a higher Sp1 binding and eNOS promoter activity
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
