Bidirectional interactions between NOX2‐type NADPH oxidase and the F‐actin cytoskeleton in neuronal growth cones

Abstract

NADPH oxidases are important for neuronal function but detailed subcellular localization studies have not been performed. Here, we provide the first evidence for the presence of functional NOX2-type NADPH oxidase complex in neuronal growth cones and its bidirectional relationship with the actin cytoskeleton. NADPH oxidase inhibition resulted in reduced F-actin content, retrograde F-actin flow, and neurite outgrowth. Stimulation of NADPH oxidase via protein kinase C activation increased levels of hydrogen peroxide in the growth cone periphery. The main enzymatic NADPH oxidase subunit NOX2/gp91phox localized to the growth cone plasma membrane and showed little overlap with the regulatory subunit p40phox. p40phox itself exhibited co-localization with filopodial actin bundles. Differential subcellular fractionation revealed preferential association of NOX2/gp91phox and p40phox with the membrane and the cytoskeletal fraction, respectively. When neurite growth was evoked with beads coated with the cell adhesion molecule apCAM, we observed a significant increase in co-localization of p40phox with NOX2/gp91phox at apCAM adhesion sites. Together, these findings suggest a bidirectional functional relationship between NADPH oxidase activity and the actin cytoskeleton in neuronal growth cones, which contributes to the control of neurite outgrowth.

Redox-guided axonal regrowth requires cyclic GMP dependent protein kinase 1: Implication for neuropathic pain

“…Integrins and semaphorin 3a (Sema3a) appear to be a major trigger of redox signals in the growth cones [40], [53]. In addition, Nadhp oxidases [54] and mitochondria locally modulate ROS signaling in the distal neurite and growth cone, and regulate the direction and the rate of neurite growth [55]. Using dimedone we were able to visualize such redox signals in growing cones, where PKG1 was colocalized with F-actin, and upon collapse, PKG1 redistributed from the tip suggesting a redox-dependent traffic that may direct PKG1 to its diverse phosphorylation targets.…”

Dissecting the role of redox signaling in neuronal development

“…Studies in Aplysia neurons revealed that pharmacological inhibition of NOX using apocynin or VAS2870 reduces actin polymerization in growth cones, decreases retrograde actin flow, reduces neurite outgrowth and modifies the structure of actin in the growth cone transition zone, impairing growth cone formation (Munnamalai and Suter ; Munnamalai et al . ; Altenhofer et al . ).…”

Contribution of NADPH-oxidase to the establishment of hippocampal neuronal polarity in culture

“…Oxidation of actin decreases its ability to polymerize (Hung et al, 2011(Hung et al, , 2010Sakai et al, 2012;Terman and Kashina, 2013). However, inhibition of NOX reduces both the F-actin content at the growth cone and the retrograde actin flow in neurons, suggesting a crosslink between NOX and actin dynamics (Munnamalai and Suter, 2009;Munnamalai et al, 2014).…”