Rational redesign of neutral endopeptidase binding to merlin and moesin proteins

Thrombomodulin: a multifunctional receptor modulating the endothelial quiescence

Thrombomodulin (TM) is a type 1 receptor best known for its function as an anticoagulant cofactor for thrombin activation of protein C on the surface of vascular endothelial cells. In addition to its anticoagulant cofactor function, TM also regulates fibrinolysis, complement, and inflammatory pathways. TM is a multidomain receptor protein with a lectin-like domain at its N-terminus that has been shown to exhibit direct anti-inflammatory functions. This domain is followed by 6 epidermal growth factor-like domains that support the interaction of TM with thrombin. The interaction inhibits the procoagulant function of thrombin and enables the protease to regulate the anticoagulant and fibrinolytic pathways by activating protein C and thrombin-activatable fibrinolysis inhibitor. TM has a Thr/Ser-rich region immediately above the membrane surface that harbors chondroitin sulfate glycosaminoglycans, and this region is followed by a single-spanning transmembrane and a C-terminal cytoplasmic domain. The structure and physiological function of the extracellular domains of TM have been extensively studied, and numerous excellent review articles have been published. However, the physiological function of the cytoplasmic domain of TM has remained poorly understood. Recent data from our laboratory suggest that intracellular signaling by the cytoplasmic domain of TM plays key roles in maintaining quiescence by modulating phosphatase and tensin homolog signaling in endothelial cells. This article briefly reviews the structure and function of extracellular domains of TM and focuses on the mechanism and possible physiological importance of the cytoplasmic domain of TM in modulating phosphatase and tensin homolog signaling in endothelial cells.

Adenoviral neutral endopeptidase gene delivery in combination with paclitaxel for the treatment of prostate cancer

Neutral endopeptidase (NEP) is a cell-surface peptidase that inhibits prostate cancer cell growth partly via inhibition of Akt kinase. We investigated the antitumor effects of an adenovirus gene delivery system (AdNEP) to restore NEP expression in DU145 prostate cancer cells in combination with paclitaxel chemotherapy. DU145 cells were infected with adenovirus expressing NEP or LacZ, treated with paclitaxel, and assessed for cell viability, Akt activation and induction of apoptosis. Athymic mice with established DU145 xenografts were injected intratumorally with AdNEP or AdLacZ and intraperitoneally with paclitaxel and monitored for tumor growth over 28 days. Compared to AdLacZ plus paclitaxel, AdNEP plus paclitaxel significantly inhibited DU145 cell growth and increased apoptosis as determined by increased caspase-3 and PARP-1 proteolytic fragments. In a xenograft model, tumor volume was reduced in mice treated with AdNEP plus paclitaxel (122.85±89.5 mm³; P<0.01) compared with mice treated with AdNEP plus saline (653.9±230.3 mm³), AdLacZ plus paclitaxel (575.9±176.6 mm³) or AdLacZ plus saline (920.2±238.2 mm³). In conclusion, these data suggest that NEP can augment taxane-induced apoptosis through inhibition of Akt/Bad signaling, and that the combination of NEP plus paclitaxel may be an effective strategy to inhibit castration-resistant prostate cancer growth.