Members of the transcription factor NF-?B and inhibitor I?B families are the key regulators of diverse array of cell signaling pathways that have profound impact on cell physiology, in particular, immuno-modulation, survival and proliferation of cell. NF-?B1 (also called p105/p50) and NF-?B2 (also called p100/p52) belong to both the NF-?B and I?B families. p105 and p100 are the precursors which processed into smaller products, p50 and p52, members of the NF-?B family. Precursors function as inhibitors of NF-?B, including their own processed products. Processing must be tightly regulated to generate appropriate ratio of unprocessed and processed forms. Many human diseases, such as autoimmune diseases and cancer, are linked to unregulated processing of p100 and p105. p105 and p100 divulge highly complex regulatory events in the NF-?B signaling module by generating all of NF-?B p50 and p52 proteins and inhibiting nearly half of all five NF-?B proteins. Like the prototypical I?B inhibitors, I?B?,-? and -?, p105 and p100 inhibitors also undergo complete degradation releasing NF-?B transcription factors. However, complete degradation events are difficult to observe in the backdrop of the processing events and thus are less appreciated. Processing of p105 is constitutive whereas that of p100 is inducible. This proposal aims to study the biochemical mechanisms of processing and complete degradation and coupling between these two events. Our hypothesis, derived from our preliminary results and published reports, is that the fundamental regulation of processing or lack of it is guided by several competing inter- and intra-domain interactions in p105 and p100, and these interactions can be altered by signaling. We propose that p105-self interaction induces a structural state that is conducive to constitutive processing whereas p100 attains that state only through signaling. We further propose that as the fully assembled NF-?B inhibitory complexes, the processing sites of p105 and p100 are masked. p105 and p100 in these assembled complexes must undergo complete degradation by cell signaling to liberate bound NF-?B. We will test our hypothesis by i) determining the three-dimensional structures of p105/p100 bound to NF-?B using x- ray crystallography, ii) identifying interaction strategies and energies of the p105/p100:NF-?B complexes, and finally, iii) studying the processing and degradation of the precursors.
Our proposed research has the potential to unravel the long-standing question of how the two NF-kappaB precursor proteins carry out dual functions both as transcription factors and inhibitors of NF-kB. Misregulation of both these proteins are strongly linked to auto-immune diseases and cancer. Current therapy against multiple myeloma function as an inhibitor of aberrant NF-kB activation. Our work will play a major role identifying new and better inhibitors.
|Wang, Vivien Ya-Fan; Li, Yidan; Kim, Daniel et al. (2017) Bcl3 Phosphorylation by Akt, Erk2, and IKK Is Required for Its Transcriptional Activity. Mol Cell 67:484-497.e5|
|Polley, Smarajit; Passos, Dario Oliveira; Huang, De-Bin et al. (2016) Structural Basis for the Activation of IKK1/?. Cell Rep 17:1907-1914|
|Fusco, Amanda J; Mazumder, Anup; Wang, Vivien Ya-Fan et al. (2016) The NF-?B subunit RelB controls p100 processing by competing with the kinases NIK and IKK1 for binding to p100. Sci Signal 9:ra96|
|Tao, Zhihua; Fusco, Amanda; Huang, De-Bin et al. (2014) p100/I?B? sequesters and inhibits NF-?B through kappaBsome formation. Proc Natl Acad Sci U S A 111:15946-51|
|Vu, Don; Huang, De-Bin; Vemu, Annapurna et al. (2013) A structural basis for selective dimerization by NF-?B RelB. J Mol Biol 425:1934-1945|
|Ghosh, Gourisankar; Wang, Vivien Ya-Fan; Huang, De-Bin et al. (2012) NF-?B regulation: lessons from structures. Immunol Rev 246:36-58|
|Tao, Zhihua; Ghosh, Gourisankar (2012) Understanding NIK regulation from its structure. Structure 20:1615-7|
|Wang, Vivien Ya-Fan; Huang, Wendy; Asagiri, Masataka et al. (2012) The transcriptional specificity of NF-?B dimers is coded within the ?B DNA response elements. Cell Rep 2:824-39|
|Huxford, Tom; Hoffmann, Alexander; Ghosh, Gourisankar (2011) Understanding the logic of I?B:NF-?B regulation in structural terms. Curr Top Microbiol Immunol 349:1-24|
|Fusco, Amanda J; Huang, De-Bin; Miller, Dustyn et al. (2009) NF-kappaB p52:RelB heterodimer recognizes two classes of kappaB sites with two distinct modes. EMBO Rep 10:152-9|
Showing the most recent 10 out of 14 publications