Structural and functional characterization of Nrf2 degradation by the glycogen synthase kinase 3/?-TrCP axis.

ABSTRACT: The transcription factor NF-E2-related factor 2 (Nrf2) is a master regulator of a genetic program, termed the phase 2 response, that controls redox homeostasis and participates in multiple aspects of physiology and pathology. Nrf2 protein stability is regulated by two E3 ubiquitin ligase adaptors, Keap1 and ?-TrCP, the latter of which was only recently reported. Here, two-dimensional (2D) gel electrophoresis and site-directed mutagenesis allowed us to identify two serines of Nrf2 that are phosphorylated by glycogen synthase kinase 3? (GSK-3?) in the sequence DSGISL. Nuclear magnetic resonance studies defined key residues of this phosphosequence involved in docking to the WD40 propeller of ?-TrCP, through electrostatic and hydrophobic interactions. We also identified three arginine residues of ?-TrCP that participate in Nrf2 docking. Intraperitoneal injection of the GSK-3 inhibitor SB216763 led to increased Nrf2 and heme oxygenase-1 levels in liver and hippocampus. Moreover, mice with hippocampal absence of GSK-3? exhibited increased levels of Nrf2 and phase 2 gene products, reduced glutathione, and decreased levels of carbonylated proteins and malondialdehyde. This study establishes the structural parameters of the interaction of Nrf2 with the GSK-3/?-TrCP axis and its functional relevance in the regulation of Nrf2 by the signaling pathways that impinge on GSK-3.

SUBMITTER: Rada P 

PROVIDER: S-EPMC3422007 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature