Transforming growth factor β-mediated site-specific Smad linker region phosphorylation in vascular endothelial cells

Kamato, Danielle, Rostam, Muhamad Ashraf, Piva, Terence J., Rezaei, Hossein Babaahmadi, Getachew, Robel, Thach, Lyna, Bernard, Rebekah, Zheng, Wenhua, Little, Peter J. and Osman, Narin (2014) Transforming growth factor β-mediated site-specific Smad linker region phosphorylation in vascular endothelial cells. Journal of Pharmacy and Pharmacology, 66 12: 1722-1733. doi:10.1111/jphp.12298


Author Kamato, Danielle
Rostam, Muhamad Ashraf
Piva, Terence J.
Rezaei, Hossein Babaahmadi
Getachew, Robel
Thach, Lyna
Bernard, Rebekah
Zheng, Wenhua
Little, Peter J.
Osman, Narin
Title Transforming growth factor β-mediated site-specific Smad linker region phosphorylation in vascular endothelial cells
Journal name Journal of Pharmacy and Pharmacology   Check publisher's open access policy
ISSN 2042-7158
0022-3573
Publication date 2014-12-01
Sub-type Article (original research)
DOI 10.1111/jphp.12298
Open Access Status Not Open Access
Volume 66
Issue 12
Start page 1722
End page 1733
Total pages 12
Place of publication Chichester, West Sussex United Kingdom
Publisher John Wiley & Sons
Language eng
Formatted abstract
Objectives
Transforming growth factor (TGF)-β regulates the function of vascular endothelial cells and may be involved in endothelial dysfunction. The canonical TGF-β pathway involves TGF-β receptor-mediated carboxy-terminal phosphorylation of Smad2; however, TGF-β signalling also activates numerous serine/threonine kinases that phosphorylate Smad2 in its linker region. The expression of phosphorylated Smad linker proteins were determined following TGF-β stimulation in the absence and presence of different serine/threonine kinase inhibitors in vascular endothelial cells.

Methods
Proteins were quantified by Western blotting using specific antibodies to individual phosphorylated Smad2 linker region residues.

Key findings
TGF-β mediated the phosphorylation of all four Smad2 linker region residues of interest. Erk and Jnk specifically phosphorylate Ser245 while all mitogen-activated protein kinases phosphorylate Ser250 and Ser255. Thr220 and Ser245 are phosphorylated by phosphoinositide 3 kinase (PI3K), while Ser255 was phosphorylated by the PI3K/Akt pathway. CDK and GSK-3 were shown to phosphorylate Thr220 and Ser245. TGF-β also mediated plasminogen activator inhibitor-1 gene expression that was attenuated by p38 and CDK inhibitors.

Conclusions
TGF-β-mediated phosphorylation of individual serine/threonine sites in the linker region of Smad2 occurs in a highly specific manner by kinases. These phosphorylations provide an opportunity to further understand a therapeutically targeted and very specific signalling pathway in vascular endothelial cells.
Keyword Cell signalling
Serine/threonine kinase
Smad linker region
Smads
Transforming growth factor-β
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Pharmacy Publications
 
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