Phosphorylation of a p38‐like MAPK is involved in sensing cellular redox state and drives atypical tubulin polymer assembly in angiosperms

Abstract

Reactive oxygen species (ROS) imbalance is a stressful condition for plant cells accompanied by dramatic changes in tubulin cytoskeleton. Here, evidence is provided that alterations in ROS levels directly interfere with the phosphorylation state of a p38-like MAPK in the angiosperms Triticum turgidum and Arabidopsis thaliana. Both oxidative stress generators and chemicals inducing ROS scavenging or decreasing ROS production resulted in the accumulation of a phospho-p46 protein similar to p38-MAPK. Importantly, the rhd2 A. thaliana mutants exhibited a remarkable increase in levels of phospho-p46. The presence of the p38-MAPK inhibitor SB203580 attenuated the response to ROS disturbance, prevented microtubule disappearance and resulted in a dramatic decrease in the number of atypical tubulin polymers. Moreover, in roots treated simultaneously with substances inducing ROS overproduction and others resulting in low ROS levels, phospho-p46 levels and the organization of tubulin cytoskeleton were similar to controls. Collectively, our experimental data suggest, for the first time in plants, that p46 functions as a putative sensor of redox state, the activation of which initiates downstream signalling events leading to microtubule disruption and subsequent assembly of atypical tubulin polymers. Thus, p46 seems to participate in perception of ROS homeostasis disturbance as well as in cellular responses to redox imbalance.

Ozone sensing and early signaling in plants: An outline from the cloud

“…Besides, phosphorylation of a p38-like MAPK was recently found involved in cellular redox sensing. It initiated signaling events leading to microtubule disruption (Livanos et al, 2014). Once again, investigations on the involvement and the mode of action of the cytoskeleton in response to O 3 should provide valuable information on this stress-specific signaling.…”

The interplay between ROS and tubulin cytoskeleton in plants

“…18 Interestingly, these plants exhibit extremely elevated levels of a p46 p38-like MAPK. 35 It was recently found that in angiosperms the p46 MAPK is implicated in sensing cellular ROS level alterations. ROS overproduction as well as elimination of ROS levels resulted in the activation of this protein.…”

“…ROS overproduction as well as elimination of ROS levels resulted in the activation of this protein. 35 Once activated, p46 drives the assembly of atypical tubulin polymers. 35 This strengthens the view that the mechanisms maintaining homeostasis during low or elevated ROS levels are connected by feedback loops and tightly linked to cytoskeletal responses.…”

“…35 Moreover, MAP65-1 is phosphorylated by several other ROS-responsive MAPKs. AtMPK3, AtMPK4, and AtMPK6, which are activated by ROS, 36 have been shown to directly phosphorylate AtMAP65-1.…”

Dehydration‐responsive nuclear proteome landscape of chickpea (Cicer arietinum L.) reveals phosphorylation‐mediated regulation of stress response

“…Nucleus, designated as the cell's control centre, hosts genetic information and regulates gene expression. Crucial biological processes such as DNA repair, replication, transcription, and signalling are accomplished by nuclear proteins (NPs) in a concerted manner (Livanos, Galatis, Gaitanaki, & Apostolakos, ). Execution of such critical functions demands multilayered regulation.…”