Signalling complexes and clusters: functional advantages and methodological hurdles

Abstract

SummarySignalling molecules integrate, codify and transport information in cells. Organisation of these molecules in complexes and clusters improves the efficiency, fidelity and robustness of cellular signalling. Here, we summarise current views on how signalling molecules assemble into macromolecular complexes and clusters and how they use their physical properties to transduce environmental information into a variety of cellular processes. In addition, we discuss recent innovations in live-cell imaging at the sub-micrometer scale and the challenges of object (particle) tracking, both of which help us to observe signalling complexes and clusters and to examine their dynamic character.

Interrogation of Inhibitor of Nuclear Factor κB α/Nuclear Factor κB (IκBα/NF-κB) Negative Feedback Loop Dynamics

“…These signaling pathways require certain elemental properties, such as sensitivity, reversibility, a capacity to be regulated, and robustness, that are crucial to reliably maintaining the organization and function of cells within organisms. In addition, these networks equip cells with the ability to distinguish persistently weak signals from background noise with high precision and selectivity (1,2). These molecular networks include sets of recurring regulation patterns, manifesting as network motifs, that link together in a variety of combinations to create a web of connectivity within a given signaling pathway or between multiple cascades (3).…”

“…In the past, elucidation of these complex molecular networks focused on identifying the key molecules within the network and biochemically defining their individual interactions (1,5). Conventional techniques typically employed to define these networks were static biochemical methodologies in vitro that were destructive, only semi-quantitative, lacked spatiotemporal resolution, and averaged information from a large number of cells.…”

An Endothelial Planar Cell Model for Imaging Immunological Synapse Dynamics

“…Whereas planar APC substrates (i.e., lipid bilayers, antibody-coated glass) provide optimal imaging (which has lead to many critical insights 7,[11][12][13][14] ), such models are inherently limited. Alternatively, details of physiologic cell-cell scanning dynamics have thus far been profoundly obscured by orientation-related imaging issues [8][9][10] . The imaging capabilities provided in the current approach overcome this obstacle to uniquely reveal otherwise undetectable three-dimensional subcellular architecture and rapid remodeling of a physiologic APC-T cell interface.…”

Mouvements cellulaires et moléculaires

“…Cette propriété est d'ailleurs à la base des récentes approches dites de nanoscopie [24,25] qui consistent, soit à affiner optiquement la zone d'excitation, soit à accumuler séquentiellement les positions de l'ensemble d'une population molé-culaire ( Figure 3A, 3B). Ces stratégies permettent de générer des images à très haute résolution, comparable à celle fournie par la microscopie électronique.…”

“…Il faut détecter et estimer les cibles au sein des images pour reconstruire et caractériser leurs trajectoires (Figure 4) [19,25]. [28], qui exploite un variant photoactivable de la GFP, et celle du STORM (stochastic optical reconstruction microscopy) [29], qui utilise les propriétés de clignotement aléatoire des fluorochromes.…”