Conformational biosensors reveal allosteric interactions between heterodimeric AT1 angiotensin and prostaglandin F2α receptors

Abstract

G protein-coupled receptors (GPCRs) are conformationally dynamic proteins transmitting ligand-encoded signals in multiple ways. This transmission is highly complex and achieved through induction of distinct GPCR conformations, which preferentially drive specific receptor-mediated signaling events. This conformational capacity can be further enlarged via allosteric effects between dimers, warranting further study of these effects. Using GPCR conformation-sensitive biosensors, we investigated allosterically induced conformational changes in the recently reported F prostanoid (FP)/angiotensin II type 1 receptor (AT1R) heterodimer. Ligand occupancy of the AT1R induced distinct conformational changes in FP compared with those driven by PGF2α in bioluminescence resonance energy transfer (BRET)-based FP biosensors engineered with luciferase (RLuc) as an energy donor in the C-tail and fluorescein arsenical hairpin binder (FlAsH)-labeled acceptors at different positions in the intracellular loops. We also found that this allosteric communication is mediated through Gα and may also involve proximal (phospholipase C) but not distal (protein kinase C) signaling partners. Interestingly, β-arrestin-biased AT1R agonists could also transmit a Gα-dependent signal to FP without activation of downstream Gα signaling. This transmission of information was specific to the AT1R/FP complex, as activation of Gα by the oxytocin receptor did not recapitulate the same phenomenon. Finally, information flow was asymmetric in the sense that FP activation had negligible effects on AT1R-based conformational biosensors. The identification of partner-induced GPCR conformations may help identify novel allosteric effects when investigating multiprotein receptor signaling complexes.

Stretch modulation of cardiac contractility: importance of myocyte calcium during the slow force response

“…Interestingly, both Ang II and PGF2α initiate signaling cascades through the activation of receptors linked to G αq . Transmission of conformational information between the AT 1 and FP receptors has been described in the presence of active G αq in vascular smooth muscle cells (Fillion et al 2019;Goupil et al 2015;Sleno et al 2017). G protein-coupled receptors (GPCRs) reportedly form a heterodimer complex in smooth muscle that allows signal integration between AT 1 and the FP receptors in the control of smooth muscle contractility (Fillion et al 2019).…”

Genome Editing Provides New Insights into Receptor-Controlled Signalling Pathways

“…In significant part this reflects that activation of these G proteins does not directly regulate second messenger levels or other easy-to-measure and high-throughput endpoints. HEK293 cells express both G12 and G13 [5] (Figure 1) and genome-editing has been used to generate clones of HEK293 cells lacking both G12 and G13 [33,34] and even lines lacking each of Gq, G11, G12, and G13 [22,34,35,36].…”

Prostaglandin FP receptor antagonists: discovery, pharmacological characterization and therapeutic utility

“…Here, AL‐8810 (FP receptor antagonist) and AS604872 (allosteric inhibitor; see above) produced trans‐inhibition of IPs production in A7r5 cells and antagonized mouse aortic contraction induced by either angiontensin II or PGF 2α (Goupil et al, ). Thus, AL‐8810 was able to apparently enter the FP receptor binding pocket to block the activity of the FP receptor and the co‐joined AT 1 receptor within the heterodimer (Sleno et al, ).…”