Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca
2+
/calmodulin-dependent protein kinase that mainly regulates protein translation. We have recently demonstrated that eEF2K protein increases in mesenteric artery from spontaneously hypertensive rats (SHR) compared with Wistar Kyoto rats. Pathogenesis of hypertension is modulated in part by vascular inflammation. We examined whether eEF2K mediates vascular inflammatory responses and development of hypertension. In human umbilical vein endothelial cells (HUVECs) and rat mesenteric arterial smooth muscle cells (SMCs), eEF2K phosphorylation was increased by TNF-α (48% increase in HUVECs and 46% increase in SMCs, n=5, P<0.01). In HUVECs, small interfering RNA (siRNA) against eEF2K inhibited induction of VCAM-1 (62% inhibition, n=4) and e-selectin (29% inhibition, n=6) as well as monocyte adhesion (43% inhibition, n=4) by TNF-α (P<0.01). eEF2K siRNA inhibited phosphorylation of JNK (76% inhibition) and NF-κB (54% inhibition) as well as reactive oxygen species (ROS) production (69% inhibition) by TNF-α (n=4, P<0.01). In SMCs, eEF2K siRNA inhibited VCAM-1 induction (41% inhibition, n=5, P<0.05) and phosphorylation of JNK (65% inhibition, n=6, P<0.01) and NF-κB (83% inhibition, n=4, P<0.05) by TNF-α. In vivo, increased blood pressure (systolic blood pressure, SHR; 199.5 mmHg vs. SHR+NH125; 159.4 mmHg, n=4, P<0.01) and increased eEF2K phosphorylation (68% inhibition, n=4), induction of VCAM-1 (62% inhibition, n=4, P<0.05) and hypertrophy (70% inhibition, n=4) in SHR mesenteric artery was normalized by long-term treatment with NH125 (500 μg/kg/day for 6 weeks). In SHR mesenteric artery, impairment of acetylcholine (ACh)-induced endothelium-dependent relaxation was normalized by NH125 (relaxation induced by 30 nM ACh, SHR; 60.4% vs. SHR+NH125; 90.0%, n=4, P<0.01). The present results for the first time demonstrated in cultured ECs and SMCs that eEF2K mediates TNF-induced inflammatory responses via ROS-dependent mechanism. It is also suggested that eEF2K may mediate development of hypertension in SHR likely via inflammation, hypertrophy and endothelial dysfunction.
Eukaryotic elongation factor 2 kinase inhibitor, A484954 induces diuretic effect in spontaneously hypertensive rats
