A human XPC protein interactome--a resource.

Abigail Lubin,Ling Zhang,Feng Gong,Victoria M White,Hua Chen

doi:10.3390/ijms15010141

Abstract

Global genome nucleotide excision repair (GG-NER) is responsible for identifying and removing bulky adducts from non-transcribed DNA that result from damaging agents such as UV radiation and cisplatin. Xeroderma pigmentosum complementation group C (XPC) is one of the essential damage recognition proteins of the GG-NER pathway and its dysfunction results in xeroderma pigmentosum (XP), a disorder involving photosensitivity and a predisposition to cancer. To better understand the identification of DNA damage by XPC in the context of chromatin and the role of XPC in the pathogenesis of XP, we characterized the interactome of XPC using a high throughput yeast two-hybrid screening. Our screening showed 49 novel interactors of XPC involved in DNA repair and replication, proteolysis and post-translational modifications, transcription regulation, signal transduction, and metabolism. Importantly, we validated the XPC-OTUD4 interaction by co-IP and provided evidence that OTUD4 knockdown in human cells indeed affects the levels of ubiquitinated XPC, supporting a hypothesis that the OTUD4 deubiquitinase is involved in XPC recycling by cleaving the ubiquitin moiety. This high-throughput characterization of the XPC interactome provides a resource for future exploration and suggests that XPC may have many uncharacterized cellular functions.

Highlights

Xeroderma pigmentosum complementation group C (XPC) is a 940 amino acid protein which harbors domains that can bind to damaged DNA and repair factors
In order to further investigate the role of XPC within the cell, we have organized the functions into several categories: DNA repair and replication, proteolysis and post-translational modifications, transcription regulation, signal transduction, and metabolism (Figure 1B)
While XPC has been known to play a major role in DNA damage and be modified by ubiquitin and ubiquitin-like factors, the other pathways indicated in this screening could represent novel functions of XPC and explain symptoms of xeroderma pigmentosum with as of yet unknown etiology

Summary

Introduction

XPC is a 940 amino acid protein which harbors domains that can bind to damaged DNA and repair factors. In complex with RAD23B and CETN2 [1], XPC recognizes DNA damage based on bulky disfigurations of DNA and recruits TFIIH to these sites, initiating the global genome nucleotide excision repair (GG-NER) pathway. XPC interacts with TFIIH to recruit the transcription factor to damaged DNA for the completion of NER [14,15]. We identified 49 proteins that interact with XPC with roles in DNA repair and replication, proteolysis and post-translational modifications, transcription regulation, signal transduction, and metabolism. The diversity of these roles indicates that XPC is involved in many more cellular processes than previously thought and provides a gateway for further understanding of the effects of xeroderma pigmentosum

Results and Discussion

Yeast Two-Hybrid Screen

Sequencing and Sequencing Data Analysis

Conclusions