A study of the role of the central region of the scaffolding protein nuclear factor-kappa B (NF-κB) essential modulator (NEMO) towards a unifying model of canonical NF-κB pathway activation
Embargo Date
2026-03-13
OA Version
Citation
Abstract
Scaffold proteins facilitate critical interactions between protein partners in the cell, often at the core of intracellular signals that regulate a diverse set of complex and essential pathways. This facilitation ranges from their traditionally known role, which is serving as more passive platforms for proteins to bind and associate together, to recently uncovered roles where they are actively coordinating the complexation of protein partners in the necessary orientations for signal propagation. This thesis focuses on the central region of the scaffold protein NF-kappaB Essential Modulator (NEMO), the master switch in the canonical NF Kappa-B pathway, pivotally controlling innate and adaptive immune function and regulating inflammatory response. Previous studies were primarily focused on the structurally known regions of NEMO, but the work described in this dissertation launched a deeper investigation into a centrally located, structurally uncharacterized region without known protein-binding partners or any other defined role. This central intervening domain (IVD) region was found to be highly conserved across vertebrates, shared in a functionally related homologue (optineurin), essential to NF-kappaB signal propagation, and responsible for mediating critical ligand-induced conformational changes. The structural dynamics and contributions to stability of this region were found to be involved in directing NEMO’s function, which was retained when this region was swapped with that of optineurin. Conversely, the introduction of disease-linked mutation in the core region of the IVD ablated normal NEMO function. A comparative computational analysis of NEMO and OPTN utilizing binding affinities and structural data highlights how their differences in interactions with binding partners affects function. Dysregulation causing overactive NF-kappaB stimulation is a chief driver of chronic inflammatory and stress disorders as well as cancer progression, thus this pathway remains a major target for therapeutic intervention. With the solitary role that NEMO plays in canonical NF-kappaB activation, compared to other pathway proteins with multiple roles, inhibition of NEMO could be indispensable in mitigating adverse off target effects. These findings reveal essential structural forces involving the central IVD region of NEMO, exerted between neighboring domains and bound partner proteins that are essential to its scaffolding function, presenting possible alternative targeting strategies useful in therapeutic modulation.
Description
2024