Shining light on the histamine H2 receptor: Synthesis of carbamoylguanidine-type agonists as a pharmacological tool to study internalization. (15th November 2021)

• Record Type: Journal Article
• Authors: Tropmann, Katharina; Seibel-Ehlert, Ulla; Littmann, Timo; Strasser, Andrea
• Is Part Of: Bioorganic & medicinal chemistry letters. Volume 52(2021)
• Publication Date: 2021-11-15
• Subjects: βarr or ARRB β-arrestin protein -- Eluc Emerald luciferase -- FLAG polypeptide protein tag with sequence motif DYKDDDDK -- Gαi2 α-subunit of the Gi2 protein that mediates inhibition of adenylyl cyclase -- Gβ1γ2 G protein β1- and γ2-subunit -- GsαS α-subunit (short splice variant) of the Gs protein that mediates stimulation of adenylyl cyclase -- GTPγS guanosine 5, -O-[gamma-thio]phosphate -- mini-G or mG engineered guanosine triphosphate hydrolase domain of Gαs subunit (long splice variant) -- Nluc NanoLuc luciferase -- RGS4 regulator of G protein signaling 4 -- qs5-HA chimeric Gαq protein incorporating a hemagglutinin epitope -- SP signal peptide: subunit A of the murine type 3 receptor for 5-hydroxytryptamine -- Sf9 Spodoptera frugiperda insect cell line; Histamine H2 receptor -- Fluorescent ligands -- Agonist bias -- Carbamoylguanidine -- Flow cytometry -- Confocal microscopy; Bioorganic chemistry -- Periodicals; Pharmaceutical chemistry -- Periodicals; 572
• DOI: 10.1016/j.bmcl.2021.128388
• Languages: English
• ISSNs: 0960-894X

Abstract

Graphical abstract: Abstract: So far, only little is known about the internalization process of the histamine H2 receptor (H2 R). One promising approach to study such dynamic processes is the use of agonistic fluorescent ligands. Therefore, a series of carbamoylguanidine-type H2 R agonists containing various fluorophores, heterocycles, and linkers (28 –40 ) was synthesized. The ligands were pharmacologically characterized in several binding and functional assays. These studies revealed a significantly biased efficacy (Emax ) for some of the compounds, e.g. 32 : whereas 32 acted as strong partial (Emax : 0.77, mini-Gs recruitment) or full agonist (Emax : 1.04, [ 35 S]GTPγS binding) with respect to G protein activation, it was only a weak partial agonist regarding β-arrestin1/2 recruitment (Emax : 0.09–0.12) and failed to promote H2 R internalization (confocal microscopy). On the other hand, H2 R internalization was observed for compounds that exhibited moderate agonistic activity in the β-arrestin1/2 pathways (Emax ≥ 0.22). The presented differently-biased fluorescent ligands are versatile molecular tools for future H2 R studies on receptor trafficking and internalization e.g. using fluorescence microscopy.