Bioenergetic and excitotoxic determinants of cofilactin rod formation

• Published in: Journal of neurochemistry 2024-05, Vol.168 (5), p.899-909
• Main Authors: Mai, Nguyen, Wu, Long, Uruk, Gökhan, Mocanu, Ebony, Swanson, Raymond A.
• Format: Article
• Language: English
• Subjects: Acetophenones - pharmacology; Actin; Actins - metabolism; Adenine; Adenosine Triphosphate - metabolism; Animals; Cells, Cultured; cofilactin rods; Cofilin; Depletion; Dizocilpine Maleate - pharmacology; Energy Metabolism - drug effects; Energy Metabolism - physiology; Excitatory Amino Acid Antagonists - pharmacology; Excitotoxicity; Glucose - deficiency; Glucose - metabolism; Glutamate receptors; glutamate signaling; Glutamic Acid - metabolism; Ischemia; Kynurenic acid; Kynurenic Acid - metabolism; Kynurenic Acid - pharmacology; NAD(P)H oxidase; NADPH oxidase; NADPH Oxidases - metabolism; NADPH-diaphorase; neurite injury; Neurons - drug effects; Neurons - metabolism; Nicotinamide; Nicotinamide adenine dinucleotide; Oxidase; Oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; oxygen‐glucose deprivation; Rats; Rats, Sprague-Dawley; Receptors
• ISSN: 0022-3042; 1471-4159; 1471-4159
• DOI: 10.1111/jnc.16065

Cofilactin rods (CARs), which are 1:1 aggregates of cofilin‐1 and actin, lead to neurite loss in ischemic stroke and other disorders. The biochemical pathways driving CAR formation are well‐established, but how these pathways are engaged under ischemic conditions is less clear. Brain ischemia produces both ATP depletion and glutamate excitotoxicity, both of which have been shown to drive CAR formation in other settings. Here, we show that CARs are formed in cultured neurons exposed to ischemia‐like conditions: oxygen–glucose deprivation (OGD), glutamate, or oxidative stress. Of these conditions, only OGD produced significant ATP depletion, showing that ATP depletion is not required for CAR formation. Moreover, the OGD‐induced CAR formation was blocked by the glutamate receptor antagonists MK‐801 and kynurenic acid; the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors GSK2795039 and apocynin; as well as an ROS scavenger. The findings identify a biochemical pathway leading from OGD to CAR formation in which the glutamate release induced by energy failure leads to activation of neuronal glutamate receptors, which in turn activates NADPH oxidase to generate oxidative stress and CARs. Cofilactin rod (CAR) formation leads to neurite degeneration after brain ischemia, but whether CAR formation is a direct result of ATP depletion or a more indirect effect of ischemic conditions has been uncertain. Here, we show that in neuronal cultures, the CAR formation induced by oxygen–glucose deprivation (OGD) is blocked by glutamate (GLU) receptor blockers, NADPH oxidase inhibition, or a free radical scavenger, despite ATP depletion. Conversely, exposure to GLU or hydrogen peroxide (H2O2) induces CAR formation in the absence of ATP depletion. Excitotoxic oxidative stress is thus the proximate cause of CAR formation in neurons subjected to ischemic conditions.