Activation of NADPH oxidase by AGE links oxidant stress to altered gene expression via RAGE

Area of Science:

• Biochemistry
• Cell Biology
• Pathophysiology

Background:

• Receptor for advanced glycation end products (RAGE) activation by AGEs generates reactive oxygen species (ROS).
• ROS generation via RAGE is implicated in the pathogenesis of AGE-related disorders like diabetes and renal failure.
• The precise mechanisms of ROS generation through RAGE signaling require further elucidation.

Purpose of the Study:

• To investigate the role of NADPH oxidase in AGE-RAGE-mediated ROS generation.
• To determine if NADPH oxidase activation contributes to oxidant stress in endothelial cells stimulated with AGEs.
• To explore the downstream effects of AGE-RAGE signaling on gene expression, specifically tissue factor and VCAM-1.

Main Methods:

• Incubation of human endothelial cells with AGE-modified red blood cells or CML adducts.
• Assessment of intracellular hydrogen peroxide generation, VCAM-1 expression, and tissue factor generation.
• Treatment with diphenyliodonium (NADPH oxidase inhibitor) and nitric oxide synthase inhibitors.
• Comparison of AGE-induced tissue factor expression in macrophages from wild-type and gp91phox-deficient mice.

Main Results:

• AGEs induced intracellular hydrogen peroxide, VCAM-1 expression, and tissue factor generation in endothelial cells.
• These effects were suppressed by diphenyliodonium but not by nitric oxide synthase inhibitors.
• Macrophages deficient in gp91phox (a subunit of NADPH oxidase) failed to upregulate tissue factor in response to AGEs.
• Wild-type macrophages showed enhanced tissue factor expression upon AGE stimulation.

Conclusions:

• NADPH oxidase plays a central role in AGE-RAGE-mediated ROS generation.
• This pathway contributes to altered gene expression in AGE-related disorders.
• Targeting NADPH oxidase may be a therapeutic strategy for managing complications associated with AGEs.