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

The intricate world of NF-κB signaling has long been a mystery, hidden within the complexities of living cells. However, a groundbreaking study has shed new light on this process by unveiling its 3D dynamics within individual cells.

By employing a sophisticated proximity ligation assay (iseqPLA), researchers were able to observe the fleeting moments when NF-κB proteins interact with one another. These interactions were then visualized using spinning disk confocal microscopy and reconstructed in three dimensions. Each interaction event was captured as a rolling-circle amplification product, and when multiple proteins were detected in close proximity, they were grouped together to represent a supercomplex.

The researchers conducted their experiments on various cell types, including NIH-3T3 mouse fibroblasts, cystic fibrosis (CF) patient-derived macrophages, and a mix of healthy and CF-donor monocyte-fibroblasts. As the cells responded to different cytokines over time, the researchers were able to track the dissociation of supercomplexes, the nuclear translocation of the NF-κB protein p65, and the negative-feedback mechanisms at play.

Three key discoveries emerged from this research. Firstly, quantifying the 3D volume of the supercomplexes provided a more accurate measurement of the nuclear-to-cytoplasmic ratio compared to traditional 2D projections, reducing the variance in these measurements. Secondly, the type of extracellular matrix coating used in the experiments influenced the proportion of NF-κB-responsive cells, suggesting that the cellular environment plays a crucial role in modulating NF-κB signaling.

Lastly, the researchers observed that macrophages in a CF model amplify paracrine NF-κB signaling in neighboring fibroblasts, highlighting the potential for cross-cellular communication in this disease.

To further contextualize their findings, the researchers utilized a single-cell Generative Pretrained Transformer (scGPT) model, fine-tuned on a curated set of transcriptomic datasets. This model placed the NF-κB gene panel within a broader feature space relevant to inflammation, providing a comprehensive view of how NF-κB signaling fits into the larger picture of cellular processes.

In conclusion, this groundbreaking study has established a robust 3D spatial interactomics workflow for dissecting the dynamics of NF-κB supercomplexes. By unraveling the intricacies of these protein assemblies within the 3D interior of a single cell, researchers are now better equipped to understand how these molecular machines contribute to inflammation in health and disease.