Transcriptional Regulation of Cystathionine-γ-Lyase in Endothelial Cells by NADPH Oxidase 4-Dependent Signaling.

The gasotransmitter, hydrogen sulfide (H2S) is recognized as an important mediator of endothelial cell homeostasis and function that impacts upon vascular tone and blood pressure. Cystathionine-γ-lyase (CSE) is the predominant endothelial generator of H2S, and recent evidence suggests that its transcriptional expression is regulated by the reactive oxygen species, H2O2. However, the cellular source of H2O2 and the redox-dependent molecular signaling pathway that modulates this is not known.

NADPH oxidase 4 regulates homocysteine metabolism and protects against acetaminophen-induced liver damage in mice.

Glutathione is the major intracellular redox buffer in the liver and is critical for hepatic detoxification of xenobiotics and other environmental toxins. Hepatic glutathione is also a major systemic store for other organs and thus impacts on pathologies such as Alzheimer's disease, Sickle Cell Anaemia and chronic diseases associated with aging. Glutathione levels are determined in part by the availability of cysteine, generated from homocysteine through the transsulfuration pathway.

Nicotinamide adenine dinucleotide phosphate oxidase-4-dependent upregulation of nuclear factor erythroid-derived 2-like 2 protects the heart during chronic pressure overload.

The transcription factor nuclear factor erythroid-derived 2-like 2 (Nrf2) controls a network of cytoprotective genes. Neither how Nrf2 is activated in the heart under hemodynamic overload nor its role and mechanism of action are known. This study aimed to investigate the activation and role of Nrf2 during chronic cardiac pressure overload.

Redox regulation of cardiomyocyte cell cycling via an ERK1/2 and c-Myc-dependent activation of cyclin D2 transcription.

Adult mammalian cardiomyocytes have a very limited capacity to proliferate, and consequently the loss of cells after cardiac stress promotes heart failure. Recent evidence suggests that administration of hydrogen peroxide (H2O2), can regulate redox-dependent signalling pathway(s) to promote cardiomyocyte proliferation in vitro, but the potential relevance of such a pathway in vivo has not been tested. We have generated a transgenic (Tg) mouse model in which the H2O2-generating enzyme, NADPH oxidase 4 (Nox4), is overexpressed within the postnatal cardiomyocytes, and observed that the hearts of 1-3week old Tg mice pups are larger in comparison to wild type (Wt) littermate controls.

Reactive oxygen at the heart of metabolism.

During heart development, the progression from a pluripotent, undifferentiated embryonic stem cell to a functional cardiomyocyte in the adult mammalian heart is characterised by profound changes in gene expression, cell structure, proliferative capacity and metabolism. Whilst the precise causal relationships between these processes are not fully understood, it is clear that the availability and cellular ability to utilise oxygen are critical effectors of cardiomyocyte differentiation and function during development. In particular, cardiomyocytes switch from a largely glycolytic-based production of ATP to predominantly β-oxidation of long-chain fatty acids to generate the cellular energy requirements.

NADPH oxidase 4 regulates cardiomyocyte differentiation via redox activation of c-Jun protein and the cis-regulation of GATA-4 gene transcription.

NADPH oxidase 4 (Nox4) generates reactive oxygen species (ROS) that can modulate cellular phenotype and function in part through the redox modulation of the activity of transcription factors. We demonstrate here the potential of Nox4 to drive cardiomyocyte differentiation in pluripotent embryonal carcinoma cells, and we show that this involves the redox activation of c-Jun. This in turn acts to up-regulate GATA-4 expression, one of the earliest markers of cardiotypic differentiation, through a defined and highly conserved cis-acting motif within the GATA-4 promoter.

Reductive stress linked to small HSPs, G6PD, and Nrf2 pathways in heart disease.

Significance: Aerobic organisms must exist between the dueling biological metabolic processes for energy and respiration and the obligatory generation of reactive oxygen species (ROS) whose deleterious consequences can reduce survival. Wide fluctuations in harmful ROS generation are circumvented by endogenous countermeasures (i.e.

Nox4 regulates Nrf2 and glutathione redox in cardiomyocytes in vivo.

NADPH oxidase-4 (Nox4) is an important modulator of redox signaling that is inducible at the level of transcriptional expression in multiple cell types. By contrast to other Nox enzymes, Nox4 is continuously active without requiring stimulation. We reported recently that expression of Nox4 is induced in the adult heart as an adaptive stress response to pathophysiological insult.

A non-apoptotic role for caspase-9 in muscle differentiation.

Caspases, a family of cysteine proteases most often investigated for their roles in apoptosis, have also been demonstrated to have functions that are vital for the efficient execution of cell differentiation. One such role that has been described is the requirement of caspase-3 for the differentiation of skeletal myoblasts into myotubes but, as yet, the mechanism leading to caspase-3 activation in this case remains elusive. Here, we demonstrate that caspase-9, an initiator caspase in the mitochondrial death pathway, is responsible for the activation of caspase-3 in differentiating C2C12 cells.