MKK6 phosphorylation regulates production of superoxide by enhancing Rac GTPase activity

Maged M Harraz; Andrea Park; Duane Abbott; Weihong Zhou; Yulong Zhang; John F Engelhardt

doi:10.1089/ars.2007.1579

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MKK6 phosphorylation regulates production of superoxide by enhancing Rac GTPase activity

Journal article

Open access

Peer reviewed

MKK6 phosphorylation regulates production of superoxide by enhancing Rac GTPase activity

Maged M Harraz, Andrea Park, Duane Abbott, Weihong Zhou, Yulong Zhang and John F Engelhardt

Antioxidants & redox signaling, Vol.9(11), pp.1803-1813

11/2007

DOI: 10.1089/ars.2007.1579

PMCID: PMC3597076

PMID: 17854274

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https://www.ncbi.nlm.nih.gov/pmc/articles/3597076View

Open Access

Abstract

Rac-dependent NADPH oxidases generate reactive oxygen species used in cell signaling and microbial killing or both. Whereas the mechanisms leading to NADPH oxidase activation are fairly well studied, the mechanisms that control downregulation of this enzyme complex remain unclear. We hypothesized that reactive oxygen species produced by NADPH oxidase may autoregulate the complex by inhibiting Rac activity. To this end, we searched for binding partners of Rac1 and identified a tyrosine-phosphorylated fragment of MKK6 that bound to Rac1 under redox-stress conditions. Constitutively active MKK6 interacted directly with Rac1 in vitro, and this interaction was enhanced when MKK6 was phosphorylated on tyrosine 219. Both Rac1 and Rac2 immunoprecipitated an MKK6 fragment under conditions that elevate cellular peroxide levels in 293 and RAW cells, respectively. Constitutively active and wild-type MKK6 enhanced Rac-GTPase activity in vitro, and their overexpression inhibited PMA-induced NADPH oxidase activation in RAW cells. In contrast, a Y219F mutant of MKK6 only partially enhanced Rac1 GTPase activity, and its overexpression did not alter PMA-induced NADPH oxidase activation in RAW cells. Last, MKK6 deficiency led to an increase in Rac1-GTP levels in brain tissue. Our findings suggest that MKK6 downregulates NADPH oxidase activity by enhancing Rac-GTPase activity.

Phosphorylation

Mutation

Oxidants - pharmacology

Tetradecanoylphorbol Acetate - pharmacology

rac GTP-Binding Proteins - metabolism

Recombinant Fusion Proteins - metabolism

rac GTP-Binding Proteins - analysis

MAP Kinase Kinase 6 - metabolism

MAP Kinase Kinase 6 - genetics

Superoxides - metabolism

Adenoviridae - genetics

Cell Line

Cells, Cultured

Hydrogen Peroxide - pharmacology

Glutathione Transferase - metabolism

Mice, Transgenic

Recombinant Fusion Proteins - chemistry

Gene Expression Regulation, Enzymologic

Macrophages - metabolism

Tyrosine - metabolism

Animals

Escherichia coli - genetics

Macrophages - drug effects

Mice

MAP Kinase Kinase 6 - chemistry

Details

Title: Subtitle: MKK6 phosphorylation regulates production of superoxide by enhancing Rac GTPase activity
Creators: Maged M Harraz - Department of Anatomy & Cell Biology, The University of Iowa, Iowa City, Iowa 52242, USA
Andrea Park
Duane Abbott
Weihong Zhou
Yulong Zhang
John F Engelhardt
Resource Type: Journal article
Publication Details: Antioxidants & redox signaling, Vol.9(11), pp.1803-1813
DOI: 10.1089/ars.2007.1579
PMID: 17854274
PMCID: PMC3597076
NLM abbreviation: Antioxid Redox Signal
ISSN: 1523-0864
eISSN: 1557-7716
Publisher: United States
Grant note: DK067928 / NIDDK NIH HHS DK51315 / NIDDK NIH HHS R01 DK067928 / NIDDK NIH HHS P30 DK054759 / NIDDK NIH HHS P30 DK54759 / NIDDK NIH HHS R01 DK051315 / NIDDK NIH HHS
Language: English
Date published: 11/2007
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Anatomy and Cell Biology; Radiation Oncology; Internal Medicine
Record Identifier: 9984025364802771

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