Heterodimerization of apelin receptor and neurotensin receptor 1 induces phosphorylation of ERK_1/2 and cell proliferation via Gαq‐mediated mechanism

Abstract

Dimerization of G protein-coupled receptors (GPCRs) is crucial for receptor function including agonist affinity, efficacy, trafficking and specificity of signal transduction, including G protein coupling. Emerging data suggest that the cardiovascular system is the main target of apelin, which exerts an overall neuroprotective role, and is a positive regulator of angiotensin-converting enzyme 2 (ACE2) in heart failure. Moreover, ACE2 cleaves off C-terminal residues of vasoactive peptides including apelin-13, and neurotensin that activate the apelin receptor (APJ) and neurotensin receptor 1 (NTSR1) respectively, that belong to the A class of GPCRs. Therefore, based on the similar mode of modification by ACE2 at peptide level, the homology at amino acid level and the capability of forming dimers with other GPCRs, we have been suggested that APJ and NTSR1 can form a functional heterodimer. Using co-immunoprecipitation, BRET and FRET, we provided conclusive evidence of heterodimerization between APJ and NTSR1 in a constitutive and induced form. Upon agonist stimulation, hetrodimerization enhanced ERK1/2 activation and increased proliferation via activation of Gq α-subunits. These novel data provide evidence for a physiological role of APJ/NTSR1 heterodimers in terms of ERK1/2 activation and increased intracellular calcium and induced cell proliferation and provide potential new pharmaceutical targets for cardiovascular disease.

Apelin receptor homodimer-oligomers revealed by single-molecule imaging and novel G protein-dependent signaling

“…Gαi1-Rluc8, Gαi2-Rluc8, Gαi3-Rluc8, Gαq-Rluc8, Gαoa-Rluc8, and Gαs-Rluc8, pET-21a(+)-GFP, FLAG-BirA-APJ, and HA-AP-APJ were constructed as described previously946.…”

“…Initially, APJ was classically described as a monomeric transmembrane receptor that forms a ternary complex together with its ligand and associated G proteins7. More recently, increasing evidence indicates that APJ may interact with other GPCRs to form heterodimers, which may selectively modulate distinct intracellular signal transduction pathways289. However, the existence and distribution of APJ homodimers and higher-order oligomers, and their interfaces and potential functions, remains controversial and has been extensively debated.…”

Apelin receptors: From signaling to antidiabetic strategy

“…On the other hand, apelin receptor can also heterodimerize with kappa opioid receptor , neurotensin receptor 1 (Bai et al, 2014a) and bradykinin 1 receptor (Bai et al, 2014b). Cotreatment of cells expressing those different heterodimers with their respective ligands and apelin enhance the phosphorylation and activity of different intracellular effectors such as endothelial nitric oxide synthase or ERK compared to cells expressing only one of the two protomers thus resulting in a significant increase in cell proliferation.…”

Interaction of lipids with the neurotensin receptor 1

“…Some transduction pathways can be suppressed by mutation or deletion of particular intracellular domains while leaving unrelated pathways intact, suggesting that pathways can be individually regulated by direct interactions with the receptor [36]. Further complexity is added when considering the potential functional consequences from receptor homo- [10,11] or heterodimerisation [37,38], and modifications such as phosphorylation, acylation and glycosylation [39]. Finally, when considering the various lipid environments that NTS1 can experience in different cell types, the possibility arises that receptor function could be fine-tuned to serve particular cell type requirements according to cell type membrane composition, adding an extra dimension of complexity to receptor modulation.…”