A Human XPC Protein Interactome—A Resource

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.

The nucleotide excision repair protein XPC is essential for bulky DNA adducts to promote interleukin-6 expression via the activation of p38-SAPK

“…Future investigations based on the use of chemical inhibitors of known kinases, siRNA libraries or protein-protein interaction screens should help to identify more components of this novel signal transduction pathway. Indeed, a recent yeast two-hybrid screen revealed MAP3K5 (aka ASK-1), a known upstream activator of p38-SAPK, as a novel interaction partner of XPC 35 . Of note, we show that BPDE still triggers p38-SAPK activation in XPA-as well as XPBand XPD-deficient cells.…”

Architecture of the human XPC DNA repair and stem cell coactivator complex

“…4), and OCT4 (4, 25), among others (46). It is possible that the XPC complex serves as a coactivator not just for OCT4 and SOX2, especially given that its transcriptional activities do not appear to be cell-type-restrained (20); therefore, the list of XPC's functional and physical partners is likely to grow.…”

XPC: Going where no DNA damage sensor has gone before

“…For instance, our group reported that XPC putatively interacts with a novel set of DNA damage and repair-related proteins, such as DNA damage-inducible transcript 3 (DDIT3) and polyhomeotic homolog 1 (PHC1) [58]. Interestingly, knockdown of XPC, but not of XPA, in HeLa cells leads to mild sensitivity to etoposide, a topoisomerase II inhibitor known to cause double-strand breaks (DSBs) [59].…”

“…Indeed, XPC has been implicated in pathways completely outside the DNA damage response. Our group has published an XPC interactome resource discussing the putative XPC interactions in signal transduction, transcription regulation, and cellular metabolism [58]. More comprehensive analyses have implicated XPC in chromosomal stability, transcriptional regulation, proteasomal degradation, and cellular viability.…”

“…Interestingly, the metabolic phenotypes of Xpc −/− mice mimic those of an aged mouse, as DNA damage and aging have long been linked [86]. Our group identified several metabolic proteins that could interact with XPC, including a phospholipase, a pyrophosphatase, a monooxygenase, and a decarboxylase [58], thereby establishing a potential link between XPC and cellular metabolism. Newer studies are also beginning to hint at a broader role for XPC in cell growth and proliferation; knockdown of XPC in A549 cells leads to decreased cell growth, migration, and a faster growth rate in tumor xengorafts [87].…”