Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology
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Cell. Physiol. Biochem. · Jan 2007
Epigallocatechin-3-O-gallate inhibits the angiotensin II-induced adhesion molecule expression in human umbilical vein endothelial cell via inhibition of MAPK pathways.
Epigallocatechin-3-O-gallate (EGCG) is the main catechin, which is derived from Camellia sinensis plant. Vascular cell adhesion molecules (VCAMs) and intercellular adhesion molecules (ICAMs) mediate the binding of inflammatory cells onto the vascular wall-promoting the early phase of atherosclerosis. In the present study, we investigated the mechanism(s) by which EGCG inhibits angiotensin II (Ang II)-induced elevation of the membrane associated VCAM-1 and ICAM-1 in human umbilical vein endothelial cells (HUVEC). ⋯ PD98059, an inhibitor of ERK1/2 inhibited the Ang II-induced increase of VCAM-1 but not of ICAM-1 in the plasma membranes. In contrast, SB203580, an inhibitor of p38 MAPK inhibited both the Ang II-induced enrichment of ICAM-1 and VCAM-1. From these results, it may be concluded that EGCG inhibits the Ang II-induced elevation of VCAM-1 and ICAM-1 in the HUVEC plasma membranes via inhibition of the p38 MAPK and the ERK1/2 signalling pathways resulting in an inhibition of the VCAM-1 and ICAM-1 transcription.
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Cell. Physiol. Biochem. · Jan 2007
A single binding motif is required for SPAK activation of the Na-K-2Cl cotransporter.
SPAK (Ste20p-related proline alanine-rich kinase) phosphorylates and activates NKCC1 (Na-K-2Cl cotransporter) in the presence of another serine/threonine kinase WNK4 (With No lysine (K)). However, whether or not the docking of SPAK to NKCC1 is a requirement for cotransporter activation has not been fully resolved. ⋯ We demonstrate that physical docking of SPAK to NKCC1 is necessary for cotransporter activity under both baseline and hyperosmotic conditions. We identify T(206) and T(211) as major phospho-acceptor sites involved in cotransporter function, with T(206) common to two separate regulatory pathways: one involving SPAK, the other involving a still unknown kinase that is responsive to forskolin/PKA stimulation.