Micropatterned supported membranes as tools for quantitative studies of the immunological synapse

Abstract

In living cells, membrane receptors transduce ligand binding into signals that initiate proliferation, specialization, and secretion of signaling molecules. Spatial organization of such receptors regulates signaling in several key immune cell interactions. In the most extensively studied of these, a T cell recognizes membrane-bound antigen presented by another cell, and forms a complex junction called the "immunological synapse" (IS). The importance of spatial organization at the IS and the quantification of its effect on signaling remain controversial topics. Researchers have successfully investigated the IS using lipid bilayers supported on solid substrates as model antigen-presenting membranes. Recent technical developments have enabled micron- and nanometre-scale patterning of supported lipid bilayers (SLBs) and their application to immune cell studies with provocative results, including spatial mutation of the IS. In this tutorial review, we introduce the IS; discuss SLB techniques, including micropatterning; and discuss various methods used to perturb and quantify the IS.

Label-Free Visualization of Ultrastructural Features of Artificial Synapses via Cryo-EM

“…Both planar and spherical substrates have been employed in these studies. 12,6−8 Spherical substrates are a powerful tool for interrogating and interfacing with cells. The formation of synapses on artificial substrates such as planar lipid bilayers requires that the cells either grow directly on these substrates or are grown separately in culture and added to the substrates at the appropriate time.…”

Probing Biomembrane Dynamics by Dual‐Wavelength Reflection Interference Contrast Microscopy

“…A relatively recent domain of interest concerns the study of membranes partially confined by patterned adhesive/repulsive domains. Experimental [26][27][28] and theoretical [21] studies on vesicle and cell adhesion to micropatterned substrates have been spurred by the aim to better understand the formation and function of the immunological synapse, for example. [29][30][31][32] Experimentally, membrane fluctuations have been probed either with scattering techniques [33,34] or flicker-spectroscopy.…”

Coarse-grained modeling of interactions of lipid bilayers with supports

“…7,8 Even interactions with whole cells have been studied. 9,10 Characterization of supported lipid bilayers has been accomplished with numerous methods including atomic force microscopy, 11 x-ray and neutron scattering and reflectometry, [12][13][14][15] nuclear magnetic resonance, 16 quartz crystal microbalance, 17 surface plasmon resonance, [18][19][20][21] ellipsometry, 6 electrical impedance spectroscopy, 15 and many versions of fluorescence microscopy such as fluorescence resonance energy transfer, 22 fluorescence recovery after photobleaching, 23 fluorescence interference contrast, 24,25 fluorescence correlation spectroscopy, 26 and total internal reflection fluorescence. 27 Phospholipid bilayers adsorb to hydrophilic surfaces to create a supported bilayer leaving a layer of water up to 5 Å thick-in addition to the hydration shell of the head groups-between the substrate and the head groups of the lipids in the proximal ͑closest to the solid͒ leaflet.…”