The Activation of GPR27 Increases Cytosolic L-Lactate in 3T3 Embryonic Cells and Astrocytes

Abstract

G-protein-coupled receptors (GPCRs) represent a family with over 800 members in humans, and one-third of these are targets for approved drugs. A large number of GPCRs have unknown physiologic roles. Here, we investigated GPR27, an orphan GPCR belonging to the family of super conserved receptor expressed in the brain, with unknown functions. Cytosolic levels of L-lactate ([lactate]i), the end product of aerobic glycolysis, were measured with the Laconic fluorescence resonance energy transfer nanosensor. In single 3T3 wild-type (WT) embryonic cells, the application of 8535 (1 µM), a surrogate agonist known to activate GPR27, resulted in an increase in [lactate]i. Similarly, an increase was recorded in primary rat astrocytes, a type of neuroglial cell abundant in the brain, which contain glycogen and express enzymes of aerobic glycolysis. In CRISPR-Cas9 GPR27 knocked out 3T3 cells, the 8535-induced increase in [lactate]i was reduced compared with WT controls. Transfection of the GPR27-carrying plasmid into the 3T3KOGPR27 cells rescued the 8535-induced increase in [lactate]i. These results indicate that stimulation of GPR27 enhances aerobic glycolysis and L-lactate production in 3T3 cells and astrocytes. Interestingly, in the absence of GPR27 in 3T3 cells, resting [lactate]i was increased in comparison with controls, further supporting the view that GPR27 regulates L-lactate homeostasis.

Potent, Selective Agonists for the Cannabinoid-like Orphan G Protein-Coupled Receptor GPR18: A Promising Drug Target for Cancer and Immunity

“…58 Although these receptors lack typical GPCR signaling, they have been shown to play roles in (patho)physiological processes, especially in cancer and immunological diseases. For instance, activation of GPR27 has been associated with an increase in cytosolic lactate levels and modulation of hepatocellular carcinoma progression, 59,60 while GPR173 activation has been linked to cell migration. 58 Blockade of GPR18 Activation by Antagonists.…”

Prognostic significance and immune characteristics of GPR27 in gastric cancer

“…G-protein-coupled receptors (GPCRs) are a super-family with more than 800 members, and some of them are not well studied [ 6 ]. G-protein-coupled receptor 27 (GPR27) is a newly identified component of GPCRs super-family.…”

Development of Ligands for the Super Conserved Orphan G Protein-Coupled Receptor GPR27 with Improved Efficacy and Potency

“…14,15 More recently, in 3T3 embryonic fibroblasts, GPR27 was shown to be linked to L-lactate homeostasis. 16 Following a screening campaign of ∼7000 compounds from a diversity-oriented synthesis library, our group has identified small-molecule GPR27 agonists I (8535) and II (7941) (Figure 1) that share a 2,4-dichlorobenzamide sulfonamide scaffold. 17 These hit compounds were selective for GPR27 compared to the other SREBs, GPR85 and GPR173.…”

“…Furthermore, GPR27 knockout mice have reduced plasma insulin and mild glucose intolerance . GPR27’s function in metabolism has also been explored in nonmammalian vertebrates, such as the zebrafish (Danio rerio), where its deletion altered insulin signaling and lipid metabolism. , More recently, in 3T3 embryonic fibroblasts, GPR27 was shown to be linked to l -lactate homeostasis …”