Activation of phospholipase C gamma 1 protects renal arteriolar VSMCs from H2O2-induced cell death

Redox-mediated signal transduction by cardiovascular Nox NADPH oxidases

The only known function of the Nox family of NADPH oxidases is the production of reactive oxygen species (ROS). Some Nox enzymes show high tissue-specific expression and the ROS locally produced are required for synthesis of hormones or tissue components. In the cardiovascular system, Nox enzymes are low abundant and function as redox-modulators. By reacting with thiols, nitric oxide (NO) or trace metals, Nox-derived ROS elicit a plethora of cellular responses required for physiological growth factor signaling and the induction and adaptation to pathological processes. The interactions of Nox-derived ROS with signaling elements in the cardiovascular system are highly diverse and will be detailed in this article, which is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System".

Activation of TRPC6 channels is essential for lung ischaemia-reperfusion induced oedema in mice

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 (Nox2^y/−) 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 Nox2^y/− 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.

The signalling cascade involved in lung ischaemia–reperfusion-induced oedema is poorly understood. Using knockout mice, Weissmann et al. propose a model in which reactive oxygen species production by endothelial NOX2 leads to phospholipase C-γ activation, DAG kinase inhibition and subsequent TRPC6 activation.

PLCγ is required for RhoGDI2-mediated cisplatin resistance in gastric cancer

Rho GDP dissociation inhibitor 2 (RhoGDI2) is a regulator of the Rho family GTPases. Recent work from our laboratory suggests that RhoGDI2 expression potentially enhances resistance to cisplatin as well as promotes tumor growth and malignant progression in gastric cancer. In this study, we demonstrate that phospholipase C-gamma (PLCγ) is required for RhoGDI2-mediated cisplatin resistance and cancer cell invasion in gastric cancer. The levels of phosphorylated PLCγ are markedly enhanced in RhoGDI2-overexpressing SNU-484 cells and, by contrast, repressed in RhoGDI2-depleted MKN-28 cells. Depletion of PLCγ expression or inhibition of its activity not only significantly increases cisplatin-induced apoptosis but also suppresses the invasive ability of RhoGDI2-overexpressing SNU-484 cells. Taken together, our results suggest that PLCγ plays a key role in RhoGDI2-mediated cisplatin resistance and cell invasion in gastric cancer cells.