3D Spatial Interactomics Maps the Dynamics of NF-κB Multiprotein Signalosomes in Single Cells

Abstract

NF{kappa}B signaling drives inflammatory responses by rapidly assembling membrane-proximal multiprotein supercomplexes, yet how these assemblies are organized in space and time within the 3D interior of a single cell has remained uncharacterized. We addressed this by profiling endogenous NF{kappa}B protein-protein interactions with an intelligent sequential proximity ligation assay (iseqPLA), read out by spinning disk confocal microscopy and 3D reconstruction. Each detected protein-protein proximity event is represented by a rolling-circle amplification product, and we treat clusters of co-localized puncta as a measure of supercomplex spatial organization. Across NIH-3T3 mouse fibroblasts, cystic fibrosis (CF) patient-derived macrophage co-cultures with IMR-90 human fibroblasts, and an independent set of healthy- and CF-donor monocyte-fibroblast co-cultures profiled by 3D iseqPLA, we tracked supercomplex dissociation, p65 nuclear translocation, and negative-feedback engagement across cytokine time courses. Three findings emerge: 3D volumetric quantification reduces the variance in nuclear-to-cytoplasmic ratio measurements relative to 2D projections, the choice of extracellular matrix coating shapes the fraction of NF{kappa}B-responsive cells, and CF airway-conditioned macrophages amplify paracrine NF{kappa}B signaling in neighboring fibroblasts in a CF model. A single-cell Generative Pretrained Transformer (scGPT) foundation model, fine-tuned on curated transcriptomic datasets, further places our NF{kappa}B gene panel within an inflammation-relevant feature space. Together, these results establish a 3D spatial interactomics workflow for dissecting supercomplex dynamics in health and disease.