PubMed Journals: J Biol Chem
Source: PMID: 12198130
⇦ ⇨ J Biol Chem. 2002 Nov 8;277(45):42769-74.
⇩ Epub 2002 Aug 26.
Phosphorylation of Nrf2 at Ser-40 by protein
kinase C regulates antioxidant response
Huang HC(1), Nguyen T, Pickett CB.
(1) Schering-Plough Research Institute,
Kenilworth, New Jersey 07033, USA.
Nrf2, a basic leucine zipper transcription
factor, is an essential activator of the
coordinated transcription of genes encoding
antioxidant enzymes and phase II detoxifying
enzymes through the regulatory sequence
termed antioxidant response element (ARE).
Recently we reported evidence for the involvement
of protein kinase C (PKC) in phosphorylating
Nrf2 and triggering its nuclear translocation
in response to oxidative stress. We show
here that phosphorylation of purified rat
Nrf2 by the catalytic subunit of PKC was
blocked by a synthetic peptide mimicking
one of the potential PKC sites. Accordingly,
Nrf2 bearing a Ser to Ala mutation at amino
acid 40 (S40A) could not be phosphorylated
by PKC. The S40A mutation did not affect
in vitro binding of Nrf2/MafK to the ARE.
However, it partially impaired Nrf2 activation
of ARE-driven transcription in a reporter
gene assay when Keap1 was overexpressed.
In vitro transcribed/translated Keap1 could
be coimmunoprecipitated with Nrf2. Phosphorylation
of wild-type Nrf2 by PKC promoted its dissociation
from Keap1, whereas the Nrf2-S40A mutant
remained associated. These findings together
with our prior studies suggest that the
PKC-catalyzed phosphorylation of Nrf2 at
Ser-40 is a critical signaling event leading
to ARE-mediated cellular antioxidant response.
DOI: 10.1074/jbc.M206911200 PMID: 12198130
[Indexed for MEDLINE]