Sphingosine-1-phosphate receptor 1 reporter mice reveal receptor activation sites in vivo

Abstract

Activation of the GPCR sphingosine-1-phosphate receptor 1 (S1P1) by sphingosine-1-phosphate (S1P) regulates key physiological processes. S1P1 activation also has been implicated in pathologic processes, including autoimmunity and inflammation; however, the in vivo sites of S1P1 activation under normal and disease conditions are unclear. Here, we describe the development of a mouse model that allows in vivo evaluation of S1P1 activation. These mice, known as S1P1 GFP signaling mice, produce a S1P1 fusion protein containing a transcription factor linked by a protease cleavage site at the C terminus as well as a β-arrestin/protease fusion protein. Activated S1P1 recruits the β-arrestin/protease, resulting in the release of the transcription factor, which stimulates the expression of a GFP reporter gene. Under normal conditions, S1P1 was activated in endothelial cells of lymphoid tissues and in cells in the marginal zone of the spleen, while administration of an S1P1 agonist promoted S1P1 activation in endothelial cells and hepatocytes. In S1P1 GFP signaling mice, LPS-mediated systemic inflammation activated S1P1 in endothelial cells and hepatocytes via hematopoietically derived S1P. These data demonstrate that S1P1 GFP signaling mice can be used to evaluate S1P1 activation and S1P1-active compounds in vivo. Furthermore, this strategy could be potentially applied to any GPCR to identify sites of receptor activation during normal physiology and disease.

Emerging biology of sphingosine-1-phosphate: its role in pathogenesis and therapy

“…The results are consistent with the idea that S1P within the vascular compartment acts on endothelial S1P 1 to minimize vascular leak during homeostatic and acute conditions (Figure 3). S1P 1 signaling reporter mice demonstrate receptor activation in endothelium under basal conditions, with enhanced S1P activation, dependent on plasma S1P, when systemic inflammation is induced (42). S1P 2 and S1P 3 are also expressed in vascular smooth muscle cells of resistance vessels and regulate vascular tone, especially during endothelial damage when plasma S1P accesses the medial smooth muscle cells (43)(44)(45)(46)(47).…”

“…When endothelial cells are damaged, platelet activation and aggregation release S1P, which leads to local release of S1P that aids in the repair of vascular injury. in vivo (42). A synthetic S1P 1 signaling pathway was genetically engineered in these mice so that a transcription factor is released from activated S1P 1 to turn on a GFP reporter gene.…”

Targeting cancer metabolism by simultaneously disrupting parallel nutrient access pathways

“…Data are representative of at least 3 independent experiments. 4 0 9 0 jci.org Volume 126 Number 11 November 2016 in the heart (22,27,28). The conformationally constrained FTY720 analog SH-BC-893, in contrast, could be used therapeutically, as it does not activate S1P 1 in reporter cells ( Figure 1, A and B).…”

HDL activation of endothelial sphingosine-1-phosphate receptor-1 (S1P1) promotes regeneration and suppresses fibrosis in the liver

“…S1P bound to ApoM-containing HDL acts as a biased agonist for endothelial S1P 1 signaling (53). Thus, we tested activation of S1P 1 signaling in LSEC after PH with a S1P 1 signaling reporter mouse ( Figure 5, A and B) (59). This reporter mouse measures signaling by endogenous Figure 5.…”