Reactive oxygen species regulate F‐actin dynamics in neuronal growth cones and neurite outgrowth

Abstract

Reactive oxygen species are well known for their damaging effects due to oxidation of lipids, proteins and DNA that ultimately result in cell death. Accumulating evidence indicates that reactive oxygen species also have important signaling functions in cell proliferation, differentiation, cell motility and apoptosis. Here, we tested the hypothesis whether reactive oxygen species play a physiological role in regulating F‐actin structure and dynamics in neuronal growth cones. Lowering cytoplasmic levels of reactive oxygen species with a free radical scavenger, N‐tert‐butyl‐α‐phenylnitrone, or by inhibiting specific sources of reactive oxygen species, such as NADPH oxidases or lipoxygenases, reduced the F‐actin content in the peripheral domain of growth cones. Fluorescent speckle microscopy revealed that these treatments caused actin assembly inhibition, reduced retrograde actin flow and increased contractility of actin structures in the transition zone referred to as arcs, possibly by activating the Rho pathway. Reduced levels of reactive oxygen species ultimately resulted in disassembly of the actin cytoskeleton. When neurons were cultured overnight in conditions of reduced free radicals, growth cone formation and neurite outgrowth were severely impaired. Therefore, we conclude that physiological levels of reactive oxygen species are critical for maintaining a dynamic F‐actin cytoskeleton and controlling neurite outgrowth.

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

“…2A, arrows). These results are consistent with the finding that actin at the growth cone of Aplysia bag cells is disorganized after NOX inhibition (Munnamalai and Suter, 2009). Second, based on the possible influence of NOX on the integrity of the actin cytoskeleton, we evaluated filopodial dynamics at the tip of the axon as a parameter for actin polymerization.…”

“…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).…”

“…Neurons were fixed and permeabilized as described previously . β3-tubulin immunofluorescence and the transient expression of the far-red fluorescent protein mKate2 (Evrogen, Moscow, Russia) were used to normalize DCFH-DA emission, similar to as described previously (Munnamalai and Suter, 2009). …”

Mammalian Numb-interacting Protein 1/Dual Oxidase Maturation Factor 1 Directs Neuronal Fate in Stem Cells

“…Treatment of PC12 cells with either nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, diphenylene iodonium, catalase, or N-acetylcysteine negated the nerve growth factor response and blocked neuronal differentiation (45,48). Furthermore, NADPH oxidase has been implicated in hippocampal long term potentiation, neuronal growth cone formation, and neurite outgrowth (49,50). However, Tsatmali et al (51) showed that ROS production does not influence the probability of a cell becoming a neuron during development.…”

Capping Protein Modulates Actin Remodeling in Response to Reactive Oxygen Species during Plant Innate Immunity

“…The interaction between ROS and actin cytoskeleton has long been recognized (Wilson and González-Billault, 2015). In mammalian cells, ROS regulate actin rearrangements associated with cellular processes such as cell adhesion, migration, wound repair, as well as neurite outgrowth (Chiarugi et al, 2003;Fiaschi et al, 2006;Munnamalai and Suter, 2009;Sakai et al, 2012;Taulet et al, 2012;Xu and Chisholm, 2014). In plant cells, ROS signaling is required for actin remodeling during the self-incompatibility response in pollen tubes and abscisic acid-induced stomatal closure (Wilkins et al, 2011;Li et al, 2014c).…”