Anti-EDN1 monoclonal antibody, clone 4H21

The Hippo pathway plays an important role in both physical and pathogenesis processes. As crucial downstream effectors of Hippo pathway, YAP is inhibited by Lats1/2 through phosphorylation. However, upstream signals that regulate the Hippo pathway have been still poorly understood. Here, we found that knockdown of CD44 reduced YAP expression and nuclear localization, but nearly had no effect on its upstream effectors, Mst1 and Lats1. Downregulated CD44 expression also significantly decreased the expression of YAP downstream effectors CTGF, Cyr61 and EDN1 at mRNA level. Our next study showed that knockdown of CD44 inhibited RhoA expression, which was consistent with RhoA knockdown mediated YAP downregulation. Furthermore, we demonstrated that over expression of the constitutively active RhoA (RhoA-V14) could block the YAP expression decrease mediated by CD44 knockdown. Moreover, downregulation of CD44 significantly promoted cell apoptosis and inhibited cell proliferation, cell cycle progression and migration, which were consistent with the effects of RNAi-mediated YAP knockdown in both A549 and HepG2 cells. Overall, data are presented showing that CD44 could act through RhoA signaling to regulate YAP expression and this study also provide new insights into the regulatory mechanisms of the Hippo-YAP pathway. (C) 2014 Elsevier Inc. All rights reserved.

A transient increase of EDN1 mRNA accumulation is observed in human vein endothelial cells (HUVECs) after a low dose of ionizing radiation. The kinetics of this mRNA accumulation parallels that of other AP1-regulated transcripts, showing a sharp peak 2 h after irradiation. This accumulation is followed by a net increase of endothelin 1 and big endothelin I in the cytoplasm that reaches a peak 4 h after irradiation. We followed the kinetics of endothelin 1 secretion in cell culture medium and did not find a detectable increase in the rate of secretion by the irradiated cells compared to sham-irradiated cells. We conclude that in HUVEC monolayers, an increase in endothelin production does not automatically correspond to an increase in secretion. These findings suggest that endothelin is an important component in the response of endothelial cells to ionizing radiation and that it could be used as a biomarker for low-dose irradiation of endothelial tissues. (c) 2007 by Radiation Research Society.