Tumor Cell Phenotype Is Sustained by Selective MAPK Oxidation in Mitochondria

Abstract

Mitochondria are major cellular sources of hydrogen peroxide (H2O2), the production of which is modulated by oxygen availability and the mitochondrial energy state. An increase of steady-state cell H2O2 concentration is able to control the transition from proliferating to quiescent phenotypes and to signal the end of proliferation; in tumor cells thereby, low H2O2 due to defective mitochondrial metabolism can contribute to sustain proliferation. Mitogen-activated protein kinases (MAPKs) orchestrate signal transduction and recent data indicate that are present in mitochondria and regulated by the redox state. On these bases, we investigated the mechanistic connection of tumor mitochondrial dysfunction, H2O2 yield, and activation of MAPKs in LP07 murine tumor cells with confocal microscopy, in vivo imaging and directed mutagenesis. Two redox conditions were examined: low 1 µM H2O2 increased cell proliferation in ERK1/2-dependent manner whereas high 50 µM H2O2 arrested cell cycle by p38 and JNK1/2 activation. Regarding the experimental conditions as a three-compartment model (mitochondria, cytosol, and nuclei), the different responses depended on MAPKs preferential traffic to mitochondria, where a selective activation of either ERK1/2 or p38-JNK1/2 by co-localized upstream kinases (MAPKKs) facilitated their further passage to nuclei. As assessed by mass spectra, MAPKs activation and efficient binding to cognate MAPKKs resulted from oxidation of conserved ERK1/2 or p38-JNK1/2 cysteine domains to sulfinic and sulfonic acids at a definite H2O2 level. Like this, high H2O2 or directed mutation of redox-sensitive ERK2 Cys214 impeded binding to MEK1/2, caused ERK2 retention in mitochondria and restricted shuttle to nuclei. It is surmised that selective cysteine oxidations adjust the electrostatic forces that participate in a particular MAPK-MAPKK interaction. Considering that tumor mitochondria are dysfunctional, their inability to increase H2O2 yield should disrupt synchronized MAPK oxidations and the regulation of cell cycle leading cells to remain in a proliferating phenotype.

The Tobacco Smoke Component, Acrolein, Suppresses Innate Macrophage Responses by Direct Alkylation of c-Jun N-Terminal Kinase

“…AMs from acrolein-exposed mice were lysed and derivatized with BH for analysis of total carbonylated proteins by streptavidin blotting (B) or Western blot analysis of purified biotinylated proteins or input lysates for RelA or JNK (C). (67). By analogy, alkylation of these corresponding Cys residues within JNK or ERK might interfere with their interaction with upstream MEK proteins, and thereby contribute to the observed inhibition of their phosphorylation.…”

The ERK Cascade: Distinct Functions within Various Subcellular Organelles

“…In this regard, it was shown that ERK1/2, as well as p38, JNK, and their respective MAPKKs, are present in the mitochondria of a murine tumor cell line, and the traffic of these MAPKs in and out of the organelle is regulated by hydrogen peroxide. 143 Another important step in understanding the mitochondrial localization, regulation, and role in mitochondrial activities was the recent proteomic study on ERK1/2-interacting proteins in the mitochondria. 96 In this study, it was demonstrated that ERK1 physically associates with structural, signaling, transport, and metabolic proteins in the mitochondria of HeLa cells.…”

FLT3-driven redox-modulation of Ezrin regulates leukaemic cell migration

“…Additionally, evidence to support a role for direct redox regulation of several components of the MAPK signalling pathway (Greene et al,2000 ;Galli et al, 2008), re-inforces the early work of Adler et al (1999), who demonstrated the redox-dependent activation of JNK via the oxidative inactivation of its inhibitor GSH-S-transferase Pi.…”

“…Recent evidence has identified a redox element in the direct regulation of c-Abl (Leonberg and Chai, 2007), Akt (Wani et al, 2011), c-AMP-dependent protein kinase (Humphries et al, 2005), Erk (Galli et al, 2008), Ca(2+)/calmodulindependent protein kinase (Erickson et al, 2008), cGMP-dependent protein kinase (PKG) Iα (Burgoyne et al, 2007), ataxia-telangiectasia mutated (ATM) protein kinase (Guo et al, 2010) and apoptosis signal-regulated kinase-1 (ASK-1) (Nadeau et al, 2007). Additionally, evidence to support a role for direct redox regulation of several components of the MAPK signalling pathway (Greene et al,2000 ;Galli et al, 2008), re-inforces the early work of Adler et al (1999), who demonstrated the redox-dependent activation of JNK via the oxidative inactivation of its inhibitor GSH-S-transferase Pi.…”