Satoshi Kameshima

A novel adipocytokine, chemerin exerts anti-inflammatory roles in human vascular endothelial cells

Chemerin is a recently identified adipocytokine which plays a role on inflammation and adipocytes metabolism. However, its function in vasculature is largely unknown. We examined the effects of chemerin on vascular endothelial inflammatory states. Treatment of human umbilical vein endothelial cells with chemerin (300 ng/ml, 20 min) induced phosphorylation of Akt (Ser473) and endothelial nitric oxide (NO) synthase (eNOS) (Ser1177). Consistently, chemerin increased intracellular cyclic GMP content. Pretreatment with chemerin (1-300 ng/ml, 24 h) significantly inhibited phosphorylation of nuclear factor (NF)-κB p65 (Ser536) and p38 as well as vascular cell adhesion molecule (VCAM)-1 expression induced by tumor necrosis factor (TNF)-α (5 ng/ml, 20 min-6 h). Inhibitor of NF-κB or p38 significantly inhibited the TNF-α-induced VCAM-1 expression. Chemerin also inhibited TNF-α-induced VCAM-1 expression in rat isolated aorta. Moreover, chemerin significantly inhibited monocytes adhesion to TNF-α-stimulated endothelial cells. The inhibitory effect of chemerin on TNF-α-induced VCAM-1 was reversed by a NOS inhibitor. Conversely, an NO donor, sodium nitroprusside significantly inhibited TNF-α-induced VCAM-1. The present results for the first time demonstrate that chemerin plays anti-inflammatory roles by preventing TNF-α-induced VCAM-1 expression and monocytes adhesion in vascular endothelial cells. The effect is mediated via inhibiting activation of NF-κB and p38 through stimulation of Akt/eNOS signaling and NO production.

Eukaryotic elongation factor 2 kinase controls proliferation and migration of vascular smooth muscle cells

Eukaryotic elongation factor 2 kinase (eEF2K), also known as calmodulin (CaM)‐dependent protein kinase (CaMK) III, is a unique member of CaMK family protein. We have recently found that expression of eEF2K protein increased in mesenteric artery from spontaneously hypertensive rats. As pathogenesis of hypertension is in part regulated by vascular structural remodelling via proliferation and migration of vascular smooth muscle cells (SMCs), we tested the hypothesis that eEF2K controls SMCs proliferation and migration.

Eukaryotic elongation factor 2 kinase mediates monocrotaline-induced pulmonary arterial hypertension via reactive oxygen species-dependent vascular remodeling

Pulmonary arterial (PA) hypertension (PAH) is a progressive and lethal disease that is caused by increased vascular contractile reactivity and structural remodeling. These changes contribute to increasing pulmonary peripheral vascular resistance, finally leading to right heart failure and death. Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca(2+)/calmodulin-dependent protein kinase. We previously revealed that eEF2K protein increases in the mesenteric artery from spontaneously hypertensive rats and partly mediates the development of hypertension via a promotion of ROS-dependent vascular inflammatory responses and proliferation and migration of vascular smooth muscle cells. However, a role of eEF2K in the pathogenesis of PAH is unknown. In the present study, we tested the hypothesis that eEF2K may be involved in the pathogenesis of PAH. PAH was induced by a single intraperitoneal injection of monocrotaline (MCT; 60 mg/kg) to rats. A specific eEF2K inhibitor, A-484954 (2.5 mg·kg(-1)·day(-1)), was intraperitoneally injected for 14 days. Long-term A-484954 treatment inhibited MCT-induced increased PA pressure. It was revealed that A-484954 inhibited MCT-induced PA hypertrophy and fibrosis but not impairment of endothelium-dependent and -independent relaxation. Furthermore, A-484954 inhibited MCT-induced NADPH oxidase-1 expression and ROS generation as well as matrix metalloproteinase-2 activation. In conclusion, the present results suggest that eEF2K at least partly mediates MCT-induced PAH via stimulation of vascular structural remodeling perhaps through NADPH oxidase-1/ROS/matrix metalloproteinase-2 pathway.

Vaspin prevents elevation of blood pressure through inhibition of peripheral vascular remodelling in spontaneously hypertensive rats.

Visceral adipose tissue‐derived serine protease inhibitor (vaspin) is a relatively novel adipocytokine with protective effects on metabolic diseases including obesity and type II diabetes. We have previously demonstrated that vaspin exerts anti‐inflammatory and antimigratory roles through antioxidative effects in vascular smooth muscle cells. As inflammatory responses and migration of smooth muscle in peripheral vascular wall are key mechanisms for the pathogenesis of hypertension, we hypothesized that vaspin could prevent the development of hypertension in in vivo hypertensive animal model.

Visceral adipose tissue-derived serine protease inhibitor augments acetylcholine-induced relaxation via the inhibition of acetylcholine esterase activity in rat isolated mesenteric artery

Visceral adipose tissue‐derived serine protease inhibitor (vaspin) is an adipocytokine with insulin‐sensitizing activity originally identified in visceral adipose tissues of obesity‐related type II diabetic rats. We previously showed that vaspin inhibits vascular cell migration and apoptosis as well as inflammatory responses, which are crucial for the development of hypertension. However, little is known about the effects of vaspin on vascular reactivity. The aim of this study was thus to explore the effects of vaspin on contraction and relaxation of isolated blood vessel.

Expression and localization of calmodulin-related proteins in brain, heart and kidney from spontaneously hypertensive rats.

Blood pressure is regulated not only by peripheral arterial resistance, but also by heart, kidney, and central nervous system. We have previously demonstrated that expression level of calmodulin-related proteins including eukaryotic elongation factor 2 kinase (eEF2K), death-associated protein kinase (DAPK)3, and histone deacetylase (HDAC)4 was specifically elevated in mesenteric artery from spontaneously hypertensive rats (SHR), which partly contributes to the development of hypertension via vascular inflammation and structural remodeling. We tested the hypothesis whether expression and localization of eEF2K, DAPK3, and HDAC4 are altered in brain, heart, and kidney from SHR. After brain, left ventricles (LV), and kidney were isolated from 12-week-old male Wistar Kyoto rats (WKY) and SHR, Western blotting and histological analysis were performed. In brain tissue, protein expression of eEF2K and HDAC4 was abundant, whereas DAPK3 protein was less. HDAC4 protein expression in SHR brain was significantly higher than that in WKY brain. In LV, protein expression of eEF2K was relatively higher than DAPK3 or HDAC4, and it was significantly higher in SHR than WKY. In kidney tissue, protein expression of DAPK3 was the highest and seemed to be localized specifically to renal tubule. The present results indicate that the increased HDAC4 in brain and increased eEF2K in LV might be at least in part related to the development of hypertension.

Coordination of changes in expression and phosphorylation of eukaryotic elongation factor 2 (eEF2) and eEF2 kinase in hypertrophied cardiomyocytes

Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) is one of the Ca2+/calmodulin-dependent protein kinases. Activated eEF2K phosphorylates its specific substrate, eEF2, which results in inhibition of protein translation. We have recently shown that protein expression of eEF2K was specifically increased in hypertrophied left ventricles (LV) from spontaneously hypertensive rats (SHR). However, phosphorylation state of eEF2K and eEF2 in hypertrophied LV is not determined. In the present study, we examined expression and phosphorylation of eEF2K and eEF2 in LV from SHR as well as the pressure overload (transverse aortic constriction: TAC)- and isoproterenol (ISO)-induced cardiac hypertrophy model. In LV from TAC mice, eEF2K expression was increased as determined by Western blotting. In LV from TAC mice and SHR, eEF2K phosphorylation at Ser366 (inactive site) was decreased. Consistently, eEF2 phosphorylation at Thr56 was increased. In LV from ISO rats, while eEF2K phosphorylation was decreased, eEF2K expression and eEF2 phosphorylation were not different as determined by Western blotting. In the results obtained from immunohistochemistry, however, total eEF2K and phosphorylated eEF2 (at Thr56) localized to cardiomyocytes were increased in LV cardiomyocytes from ISO rats. Accordingly, the increased expression and the decreased phosphorylation of eEF2K and the increased phosphorylation of eEF2 in hypertrophied LV were common to all models in this study. The present results thus suggest that cardiac hypertrophy may be regulated at least partly via eEF2K-eEF2 signaling pathway.