Nat Commun. 2017 Jun 16;8:15700. doi: 10.1038/ncomms15700.
Single-cell profiling reveals heterogeneity and functional patterning of GPCR expression in the vascular system.
G-protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors in eukaryotes; they transduce signals of numerous physicochemical stimuli including neurotransmitters, hormones, metabolic or olfactory cues, and light. GPCRs have regulatory functions in almost all organ systems, and dysregulation of GPCR signalling has been implicated in the pathogenesis of many diseases. The unique combination of diversity and specificity within the GPCR family, together with the fact that they are readily targetable by exogenous agonists and antagonists, has made GPCRs a most successful group of drug targets. However, although the market share of GPCR-targeting drugs is with 30–40% high, the overall number of targeted GPCR is with ~30 rather low, suggesting that the potential of GPCRs as drug targets is not yet fully exploited. One approach to the development of new GPCR-based therapies is the detailed expression analysis in functionally relevant cell subpopulations, for example, in subgroups of vascular cell types. While GPCR expression has been studied in bulk cDNA of whole vessels or cultured cells, the knowledge about GPCR expression in individual freshly isolated vascular cell types is insufficient. To address this issue, the authors performed a microfluidic-based single-cell GPCR expression analysis in primary endothelial cells and vascular smooth muscle cells from different vascular beds and found that GPCR expression patterns are quite heterogeneous in all cell types. Inflammatory activation in murine models of sepsis or atherosclerosis results in characteristic changes in the GPCR repertoire, and they identified functionally relevant subgroups of cells that are characterized by specific GPCR patterns. The authors furthermore show that dedifferentiating smooth muscle cells upregulate GPCRs such as Gpr39, Gprc5b, Gprc5c, or Gpr124, and that selective targeting of Gprc5b modulates their differentiation state. Hence, single-cell profiling identifies receptors expressed on pathologically relevant subpopulations and provides a basis for the development of new therapeutic strategies in vascular diseases.
Single-cell GPCR expression analysis in individual vascular cells. A, Workflow of the single-cell expression analysis. B, Heat map indicating similarities/dissimilarities between 60 individual aortal smooth muscle cells (SMao): A small subpopulation of cells (cluster 3, left lower corner) clearly differs from the rest. C, Heat map of GPCR expression in individual SMao (each column one cell; cluster 3 cells are shown on the right): Cluster 3 cells show signs of dedifferentiation (increased expression of Icam1, Vcam1, collagen isoforms; reduced expression of contractile markers) and a specific GPCR repertoire.