NF-?B is a conserved transcription factor that plays an essential role in the host defense to infection. While considerable advances have been made in our understanding of how NF-?B is activated, lesser is known about how its activity is terminated. Nevertheless, in terms of disease mechanism, it is likely that alterations in the mechanisms responsible for terminating NF-?B play a central role in persistent inflammation. Studies supported by this grant identified that the degradation of DNA-bound NF-?B subunits is a critical mechanism for transcriptional termination. We identified a ubiquitin ligase responsible for these effects, which contains as an essential cofactor the protein known as COMMD1. This pathway primarily limits the expression of pro-inflammatory genes and post-translational modifications (PTMs) of the NF-?B subunit RelA are required for protein degradation. Key outstanding questions include whether COMMD1 can control inflammation in vivo, how is this pathway specifically regulating pro-inflammatory genes, and what are the precise PTMs that trigger RelA ubiquitination. Our goal is to investigate the role of COMMD1 in inflammation in vivo and to uncover key mechanisms that control its activity in the innate immune system. Based on preliminary data we hypothesize that COMMD1 is an anti-inflammatory factor that cooperates with inducible PTMs such as sumoylation and phosphorylation in order to regulate pro-inflammatory genes. In pursuit of our goal, we propose these Specific Aims: (1) Role of Commd1 in inflammatory responses in vivo: We find that COMMD1 expression is repressed in the setting of inflammatory diseases, suggesting that this phenomenon may contribute to persistent and/or more severe inflammation. To test this notion, we have generated myeloid specific Commd1-/- mice, which display increased susceptibility to LPS administration. Here we will utilize this unique mouse model to evaluate the role of termination mechanisms in the control of inflammation during sepsis. (2) Basis for gene-specific chromatin recruitment of COMMD1: Gene-specific recruitment of COMMD1 occurs through a yet unknown mechanism. Preliminary studies suggest that SUMO binding by COMMD1 is responsible for chromatin binding. Here we will examine the link between SUMO binding and chromatin recruitment to pro-inflammatory gene promoters. The relevance of these events in immune regulation will be assessed by introducing SUMO binding defective mutants into Commd1-/- myeloid cells. (2) Control of termination by PTMs of NF-?B /RelA: In addition to COMMD1 recruitment to chromatin, PTMs of RelA are required for protein degradation. In this Aim we will define the PTMs required to target RelA for degradation and will assess the biological significance of these PTMs by reintroducing degradation-resistant forms of RelA into rela-/- myeloid cells. Altogether, this proposal will tackle a critically significant problem that will propel the NF-?B field forward by providing important insights into homeostatic mechanisms that prevent persistent inflammation.
Persistent inflammation is a central mechanism in human disease, leading to tissue destruction and an increased risk for cancer. It is likely that alterations in the mechanisms that terminate inflammatory responses play a significant role in persistent inflammation. Nevertheless, this aspect of inflammation is less studied. This proposal is specifically focused on the termination pathways that control the transcription factor NF- B, a critical player in the inflammatory response.
|Bartuzi, Paulina; Billadeau, Daniel D; Favier, Robert et al. (2016) CCC- and WASH-mediated endosomal sorting of LDLR is required for normal clearance of circulating LDL. Nat Commun 7:10961|
|Jia, Da; Zhang, Jin-San; Li, Fang et al. (2016) Structural and mechanistic insights into regulation of the retromer coat by TBC1d5. Nat Commun 7:13305|
|Starokadomskyy, Petro; Gemelli, Terry; Rios, Jonathan J et al. (2016) DNA polymerase-Î± regulates the activation of type I interferons through cytosolic RNA:DNA synthesis. Nat Immunol 17:495-504|
|Phillips-Krawczak, Christine A; Singla, Amika; Starokadomskyy, Petro et al. (2015) COMMD1 is linked to the WASH complex and regulates endosomal trafficking of the copper transporter ATP7A. Mol Biol Cell 26:91-103|
|Li, Haiying; Koo, Yeon; Mao, Xicheng et al. (2015) Endosomal sorting of Notch receptors through COMMD9-dependent pathways modulates Notch signaling. J Cell Biol 211:605-17|
|Bartuzi, Paulina; Wijshake, Tobias; Dekker, Daphne C et al. (2014) A cell-type-specific role for murine Commd1 in liver inflammation. Biochim Biophys Acta 1842:2257-65|
|Li, Haiying; Chan, Lillienne; Bartuzi, Paulina et al. (2014) Copper metabolism domain-containing 1 represses genes that promote inflammation and protects mice from colitis and colitis-associated cancer. Gastroenterology 147:184-195.e3|
|Colleran, Amy; Collins, Patricia E; O'Carroll, Christine et al. (2013) Deubiquitination of NF-ÎºB by Ubiquitin-Specific Protease-7 promotes transcription. Proc Natl Acad Sci U S A 110:618-23|
|ZieschÃ©, Elisabeth; Kettner-Buhrow, Daniela; Weber, Axel et al. (2013) The coactivator role of histone deacetylase 3 in IL-1-signaling involves deacetylation of p65 NF-ÎºB. Nucleic Acids Res 41:90-109|
|Starokadomskyy, Petro; Gluck, Nathan; Li, Haiying et al. (2013) CCDC22 deficiency in humans blunts activation of proinflammatory NF-ÎºB signaling. J Clin Invest 123:2244-56|
Showing the most recent 10 out of 20 publications