Surface oxidase and oxidative stress propagation in aging

Area of Science:

• Biochemistry
• Cell Biology
• Aging Research

Background:

• Aging is associated with increased mitochondrial DNA lesions and cell-surface reactive oxygen species (ROS).
• Previous studies lacked a specific terminal oxidase to explain the link between plasma membrane redox changes and aging.
• Mitochondrial dysfunction leads to anaerobic metabolism and NADH accumulation, necessitating plasma membrane oxidoreductase (PMOR) activity for cellular survival.

Purpose of the Study:

• To identify the terminal oxidase responsible for ROS generation at the plasma membrane during aging.
• To elucidate the role of the plasma membrane oxidoreductase (PMOR) system in linking mitochondrial dysfunction to cellular aging.
• To investigate the potential anti-aging mechanisms of coenzyme Q.

Main Methods:

• Characterization of a novel plasma-membrane-associated hydroquinone oxidase, CNOX (constitutive plasma membrane NADH oxidase).
• Investigating the electron transport chain function of CNOX within the PMOR system.
• Assessing the generation of ROS at the cell surface and its inhibition by coenzyme Q.

Main Results:

• Identified CNOX as the terminal oxidase for the PMOR electron transport chain.
• Demonstrated that hyperactivity of the PMOR system leads to NADH oxidase (NOX) activity, generating cell-surface ROS.
• Showed that coenzyme Q inhibits superoxide generation by NOX forms associated with aging.

Conclusions:

• CNOX links mitochondrial DNA damage to cell-surface ROS accumulation, propagating the aging cascade.
• The PMOR system's hyperactivity contributes to aging through cell-surface ROS generation.
• Coenzyme Q's inhibition of NOX-derived ROS provides a mechanistic basis for its anti-aging properties.