Signal transduction profiling using label-free biosensors

Abstract

Knowledge of the way in which ligands modulate cellular responses via membrane-associated receptors is of central importance to drug discovery and elucidation of signal transduction pathways. Biophysical label-free methods can be used to characterize ligand and drug candidate interactions with neurotransmitters, cytokine receptors, tyrosine kinase receptors, ligand- and voltage-gated ion channels, G protein-coupled receptors (GPCRs), and antibody receptors. Ligand or drug candidate screening typically involves selecting ligands or subsets of a compound library for analysis, transfecting a cell line overexpressing the target receptor, then monitoring one or two downstream reporters of receptor activation such as Ca(2+), cAMP, inositol phosphate, etc. Inevitably, this process leads to a data set predicated by these selections. In contrast, label-free screening techniques allow a holistic, pathway-independent screening strategy to provide a functional or phenotypic readout of receptor activation. Detection techniques that measure changes in cell conductance, viscoelastic properties, refractive index, and other optical parameters that are modulated as a consequence of receptor activation are reviewed.

Label-Free Biosensors for Cell Biology

“…Similar to SPR, RWG also employs an evanescent wave for detection, and thus, was initially developed for biomolecular interaction analysis [27,28]. In recent years, large-scale fabrication, together with new biosensor and instrument designs as well as advanced assay protocols, has made RWG system the first commercial platform for high throughput biochemical and cell-based assays [9,[29][30][31][32][33][34][35][36][37][38]. Commercial products include Epic system from Corning Inc., EnSpire multimodal reader containing Epic technology from PerkinElmer, and BIND system from SRU BioSystems (Figure 2(b)).…”

Liposome fusion on proteinaceous S-layer lattices triggered viaβ-diketone ligand–europium(iii) complex formation

“…1,2 Furthermore, a broad range of surface-sensitive techniques are now available to study all the previously mentioned issues. 3 The present communication deals with the formation and characterization of a biomimetic model lipid membrane generated on crystalline bacterial cell surface layers (S-layers). S-Layer proteins can be recrystallized on a broad spectrum of solid substrates including gold-and silicon dioxide-coated surfaces.…”

Using label-free screening technology to improve efficiency in drug discovery

“…They have been particularly useful in GPCR drug discovery programs, as they measure whole cell responses that do not discriminate between the different G proteins. Hence, these biosensors are able to detect signaling via one or more G proteins in a single assay (reviewed in refs [20,[27][28][29][30]). An in-depth biophysical explanation on these technologies is beyond the scope of this review, but a brief overview follows.…”