The clinical efficacy of TNF-specific antagonists in the treatment of rheumatoid arthritis (RA) points to the critical role of TNF in RA pathogenesis. Binding of TNF to one of its receptors, TNF receptor 1 (TNFR1) can activate NF-kB transcription factors leading to gene expression or the caspase pathway leading to apoptosis. Recent studies have shown that NF-kB induces the expression of anti-apoptotic genes, which then antagonize the apoptosis pathway that is concurrently activated. Therefore, an important question is what are the anti-apoptotic genes regulated by NF-kB and how do they inhibit apoptosis. A Jurkat T cell mutant that is deficient in IKK /NEMO, an essential component of the NF-kB signaling pathway, has been isolated and as a result of this deficiency, this mutant exhibits a profound increase in sensitivity to TNF-induced apoptosis. A20, a NP- B-regulated gene, effectively blocks TNF-induced apoptosis in the mutant cell by blocking either RIP, a death domain kinase in the TNF pathway, or a molecule upstream of RIP.
In Specific Aim 1, the precise molecular target of A20 will be defined by epistasis staging studies, combined with the testing of hypothesis that were formulated based on our current understanding of proximal TNFR1 signal transduction.
In Specific Aim 2, the mechanism utilized by A20 will be examined by identifying proteins that interact with A20. The approaches used will be based on the de novo interaction between A20 with its partners, which can be isolated by anti-A20 antibodies. A number of schemes will be used subsequently to identify the associated partners.
In Specific Aim3, a search for genes that are no longer upregulated by TNF in this mutant cell line will be conducted and then functionally tested for their ability to disrupt the apoptosis pathway. The end result of this project will be a greater knowledge of the pathways and downstream genes regulated by TNF, which may suggest additional avenues for pharmacological modulation in RA.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI052417-01
Application #
6535729
Study Section
Allergy and Immunology Study Section (ALY)
Program Officer
Johnson, David R
Project Start
2002-06-01
Project End
2007-05-31
Budget Start
2002-06-01
Budget End
2003-05-31
Support Year
1
Fiscal Year
2002
Total Cost
$296,625
Indirect Cost
Name
Mount Sinai School of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
114400633
City
New York
State
NY
Country
United States
Zip Code
10029
Ting, Adrian T; Bertrand, Mathieu J M (2016) More to Life than NF-?B in TNFR1 Signaling. Trends Immunol 37:535-545
Legarda, Diana; Justus, Scott J; Ang, Rosalind L et al. (2016) CYLD Proteolysis Protects Macrophages from TNF-Mediated Auto-necroptosis Induced by LPS and Licensed by Type I IFN. Cell Rep 15:2449-61
Justus, Scott J; Ting, Adrian T (2015) Cloaked in ubiquitin, a killer hides in plain sight: the molecular regulation of RIPK1. Immunol Rev 266:145-60
O'Donnell, Marie Anne; Ting, Adrian T (2012) NF?B and ubiquitination: partners in disarming RIPK1-mediated cell death. Immunol Res 54:214-26
O'Donnell, Marie Anne; Hase, Hidenori; Legarda, Diana et al. (2012) NEMO inhibits programmed necrosis in an NFýýB-independent manner by restraining RIP1. PLoS One 7:e41238
O'Donnell, Marie Anne; Perez-Jimenez, Eva; Oberst, Andrew et al. (2011) Caspase 8 inhibits programmed necrosis by processing CYLD. Nat Cell Biol 13:1437-42
O'Donnell, Marie Anne; Ting, Adrian T (2011) RIP1 comes back to life as a cell death regulator in TNFR1 signaling. FEBS J 278:877-87
O'Donnell, Marie Anne; Ting, Adrian T (2010) Chronicles of a death foretold: dual sequential cell death checkpoints in TNF signaling. Cell Cycle 9:1065-71
Legarda-Addison, D; Hase, H; O'Donnell, M A et al. (2009) NEMO/IKKgamma regulates an early NF-kappaB-independent cell-death checkpoint during TNF signaling. Cell Death Differ 16:1279-88
O'Donnell, Marie Anne; Legarda-Addison, Diana; Skountzos, Penelopi et al. (2007) Ubiquitination of RIP1 regulates an NF-kappaB-independent cell-death switch in TNF signaling. Curr Biol 17:418-24

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