Supplemental Material for Xu et al., 2018

Animals utilize conserved mechanisms to regulate oxidative
stress. The <i>C. elegans</i> SKN-1 protein
is homologous to the vertebrate Nrf (NF-E2-related
factor) family of cap 'n' collar (CnC) transcription factors and functions as a core regulator of
xenobiotic and oxidative stress responses. The WD40 repeat-containing protein WDR-23
is a key negative regulator of SKN-1 activity. We previously found that the oxidative
stress induced by excess iodide can be relieved by loss of function in the
BLI-3/TSP-15/DOXA-1 dual oxidase complex. To further understand the molecular
mechanism of this process, we screened for new mutants that can survive in
excess iodide and identified gain-of-function mutations in <i>skn-1</i> and loss-of-function mutations in <i>wdr-23</i>. The SKN-1C isoform functions in
the hypodermis to affect animal’s response to excess iodide, while the SKN-1A
isoform appears to play a minor role. <i>wdr-23(lf)</i>
can interact with <i>bli-3</i> mutations in
a manner different from <i>skn-1(gf)</i>. Transcriptome
studies suggest that excess iodide causes developmental arrest largely independent
of changes in gene expression, and <i>wdr-23(lf)
</i>could affect the expression of a subset of genes by a mechanism different
from SKN-1 activation. We propose that WDR-23 and SKN-1 coordinate with the
BLI-3/TSP-15/DOXA-1 dual oxidase complex in response to iodide-triggered oxidative
stress.