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Heteromerization of GPR 55 and cannabinoid CB 2 receptors modulates signalling
Author(s) -
Balenga N A,
MartínezPinilla E,
Kargl J,
Schröder R,
Peinhaupt M,
Platzer W,
Bálint Z,
Zamarbide M,
DopesoReyes I G,
Ricobaraza A,
PérezOrtiz J M,
Kostenis E,
Waldhoer M,
Heinemann A,
Franco R
Publication year - 2014
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.12850
Subject(s) - hek 293 cells , receptor , g protein coupled receptor , microbiology and biotechnology , mapk/erk pathway , cannabinoid receptor , chemistry , signal transduction , biology , biochemistry , agonist
Background and Purpose Heteromerization of GPCR s is key to the integration of extracellular signals and the subsequent cell response via several mechanisms including heteromer‐selective ligand binding, trafficking and/or downstream signalling. As the lysophosphatidylinositol GPCR 55 ( GPR 55) has been shown to affect the function of the cannabinoid receptor subtype 2 ( CB 2 receptor) in human neutrophils, we investigated the possible heteromerization of CB 2 receptors with GPR 55. Experimental Approach The direct interaction of human GPR 55 and CB 2 receptors heterologously expressed in HEK 293 cells was assessed by co‐immunoprecipitation and bioluminescence resonance energy transfer assays. The effect of cross‐talk on signalling was investigated at downstream levels by label‐free real‐time methods ( E pic dynamic mass redistribution and C ell K ey impedance assays), ERK 1/2‐ MAPK activation and gene reporter assays. Key Results GPR 55 and CB 2 receptors co‐localized on the surface of HEK 293 cells, co‐precipitated in membrane extracts and formed heteromers in living HEK 293 cells. Whereas heteromerization led to a reduction in GPR 55‐mediated activation of transcription factors (nuclear factor of activated T ‐cells, NF ‐κ B and cAMP response element), ERK 1/2‐ MAPK activation was potentiated in the presence of CB 2 receptors. CB 2 receptor‐mediated signalling was also affected by co‐expression with GPR 55. Label‐free assays confirmed cross‐talk between the two receptors. Conclusions and Implications Heteromers, unique signalling units, form in HEK 293 cells expressing GPR 55 and CB 2 receptors. The signalling by agonists of either receptor was governed (i) by the presence or absence of the partner receptors (with the consequent formation of heteromers) and (ii) by the activation state of the partner receptor.