Abstract 3892: Discovery and analysis of COMMD1 in the DNA damage response network

Abstract

Abstract Spatially distinct domains impart functionality to the proteins and are often under evolutionary pressure to maintain sequence and/or structure. The BRCA1 C-terminal (BRCT) domain has an established role in cancer susceptibility and in the DNA damage response (DDR), as mutations in cases of familial breast cancer often result in a truncated protein lacking the two BRCT domains which are required for interactions with proteins such as p53, ABRAXAS, BACH1, and CtIP. BRCT domains can occur as singletons or as tandem domains (tBRCT) that function as a single cohesive structural unit involved in binding phosphorylated peptides targeted by PI3K-like proteins such as ATM in response to DNA damage. Using the Yeast Two-Hybrid system (Y2H) as well as Tandem Affinity Purification coupled to mass spectrometry (TAP-MS), we have built a domain centric protein-protein interaction network for a subset of tBRCT domains from BRCA1, TP53BP1, LIG4, PAXIP1, ECT2, BARD1, and MDC1. Evaluation of this network has revealed a number of interesting interactions and highlighted the interconnectivity potential found in these domains. Analysis of this network has revealed several interesting proteins that are highly interconnected with tBRCT domains, such as COMMD1 (an important regulator of copper homeostasis, sodium transport, NF-κB, and HIF-1), which has not yet been characterized to participate in the DDR, but was found to interact with the tBRCT domains of BARD1, BRCA1, and LIG4. Furthermore, an earlier Y2H screen conducted by our laboratory found COMMD1 as an interaction partner of CHK2. Therefore, we sought to determine the role of COMMD1 in response DNA damaging agents. Convincingly, the levels of COMMD1 are inversely related to apoptotic induction caused by cisplatin and doxorubicin. Furthermore, CHK2 signaling appears to control the ability of COMMD1 to enhance cisplatin induced apoptosis as wild type but not CHK2-/- HCT116 cells exhibited a repression in cisplatin induced apoptosis when COMMD1 was over expressed. These results indicate the importance of COMMD1 for cellular susceptibility to traditional chemotherapeutics. Currently, we are exploring the mechanisms by which COMMD1 in coordination with tBRCT domain containing proteins and CHK2 sensitizes cells to DNA damaging agents. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3892. doi:10.1158/1538-7445.AM2011-3892