Peroxiredoxin 1 interacts with and blocks the redox factor APE1 from activating interleukin-8 expression.

Hassan Nassour,Nicolas Brosseau,Dindial Ramotar,Zhiqiang Wang,Moulay A Alaoui-Jamali,Arturo Papaluca,Amine Saad,El Bachir Affar

doi:10.1038/srep29389

Abstract

APE1 is an essential DNA repair protein that also possesses the ability to regulate transcription. It has a unique cysteine residue C65, which maintains the reduce state of several transcriptional activators such as NF-κB. How APE1 is being recruited to execute the various biological functions remains unknown. Herein, we show that APE1 interacts with a novel partner PRDX1, a peroxidase that can also prevent oxidative damage to proteins by serving as a chaperone. PRDX1 knockdown did not interfere with APE1 expression level or its DNA repair activities. However, PRDX1 knockdown greatly facilitates APE1 detection within the nucleus by indirect immunofluorescence analysis, even though APE1 level was unchanged. The loss of APE1 interaction with PRDX1 promotes APE1 redox function to activate binding of the transcription factor NF-κB onto the promoter of a target gene, the proinflammatory chemokine IL-8 involved in cancer invasion and metastasis, resulting in its upregulation. Depletion of APE1 blocked the upregulation of IL-8 in the PRDX1 knockdown cells. Our findings suggest that the interaction of PRDX1 with APE1 represents a novel anti-inflammatory function of PRDX1, whereby the association safeguards APE1 from reducing transcription factors and activating superfluous gene expression, which otherwise could trigger cancer invasion and metastasis.

Highlights

In order for APE1 to execute its role in DNA repair and gene regulation, there must be regulatory mechanisms that switch on/off- and fine-tune the different APE1 activities and these include (i) alteration in APE1 redox state[13], (ii) translocation of APE1 from the cytoplasm to the nucleus[14], and (iii) modulation of APE1 by post-translational modification (PTMs)[5,15,16] and proteolytic cleavage of the N-terminal 33 amino acid domain[17]
We show that PRDX1 knockdown enhanced APE1 redox activity, and which acts via the transcription factor NF-κB to turn on expression of the proinflammatory chemokine interleukin-8 (IL-8) that has been shown to play a role in cancer invasion and metastasis[20,21]
Since NF-κB is reported to activate the expression of IL-840,41 and that APE1 can maintain this transcription factor in its active reduced state, we explored whether the mechanism by which the knockdown of PRDX1 led to the upregulation of IL-8 would involve NF-κB

Summary

Introduction

In order for APE1 to execute its role in DNA repair and gene regulation, there must be regulatory mechanisms that switch on/off- and fine-tune the different APE1 activities and these include (i) alteration in APE1 redox state[13], (ii) translocation of APE1 from the cytoplasm to the nucleus[14], and (iii) modulation of APE1 by post-translational modification (PTMs)[5,15,16] and proteolytic cleavage of the N-terminal 33 amino acid domain[17]. To test whether APE1 and PRDX1 belong to a complex, we carried out co-immunoprecipitation experiments with anti-FLAG resin using total protein extracts derived from HeLaS cells carrying either the empty pOZ vector as control or pOZN-FH-APE1 under conditions where the cells were untreated or treated with H2O2 (25 μM for 1 h).

Results

Conclusion