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Activation of TRPC6 channels is essential for lung ischaemia–reperfusion induced oedema in mice
(2012)
Lung ischaemia–reperfusion-induced oedema (LIRE) is a life-threatening condition that causes pulmonary oedema induced by endothelial dysfunction. Here we show that lungs from mice lacking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox2y/−) or the classical transient receptor potential channel 6 (TRPC6−/−) are protected from LIR-induced oedema (LIRE). Generation of chimeric mice by bone marrow cell transplantation and endothelial-specific Nox2 deletion showed that endothelial Nox2, but not leukocytic Nox2 or TRPC6, are responsible for LIRE. Lung endothelial cells from Nox2- or TRPC6-deficient mice showed attenuated ischaemia-induced Ca2+ influx, cellular shape changes and impaired barrier function. Production of reactive oxygen species was completely abolished in Nox2y/− cells. A novel mechanistic model comprising endothelial Nox2-derived production of superoxide, activation of phospholipase C-γ, inhibition of diacylglycerol (DAG) kinase, DAG-mediated activation of TRPC6 and ensuing LIRE is supported by pharmacological and molecular evidence. This mechanism highlights novel pharmacological targets for the treatment of LIRE.
Introduction: Efficacy of currently approved anti-HIV drugs is hampered by mutations of the viral enzymes, leading invariably to drug resistance and chemotherapy failure. Recent data suggest that cellular co-factors also represent useful targets for anti-HIV therapy. We have recently provided evidence for the possibility to block HIV-1 replication by targeting its cellular cofactor DDX3.
Material and methods: Molecular modeling and in silico technologies were applied to rationally design small molecules specifically targeting the RNA binding site of human DDX3. Biochemical studies of mutated DDX3 enzymes were also used to identify additional potential drug binding sites.
Results
Optimization of compounds identified by application of a high-throughput docking approach afforded a promising lead compound which proved to inhibit both the helicase and ATPase activity of DDX3 and to reduce the viral load of peripheral blood mononuclear cells (PBMC) infected with HIV-1. A novel interaction site has been also identified in DDX3, which, when blocked, can reduce viral replication, representing an additional target for small molecules inhibitors.
Conclusions: We have identified the first inhibitors of HIV-1 replication targeting the RNA binding site of the cellular cofactor human DDX3. These compounds may offer superior selectivity over the ATP-competitive inhibitors previously developed. In addition, a novel RNA interacting motif specific to DDX3 has been identified, opening new venues for HIV-1 drug development.