Cannabinoid receptor interacting protein (CRIP1a) attenuates CB1R signaling in neuronal cells

Cell Signal. 2015 Mar;27(3):716-726. doi: 10.1016/j.cellsig.2014.11.006. Epub 2014 Nov 17.


CB1 cannabinoid receptors (CB1R) are one of the most abundantly expressed G protein coupled receptors (GPCR) in the CNS and regulate diverse neuronal functions. The identification of GPCR interacting proteins has provided additional insight into the fine-tuning and regulation of numerous GPCRs. The cannabinoid receptor interacting protein 1a (CRIP1a) binds to the distal carboxy terminus of CB1R, and has been shown to alter CB1R-mediated neuronal function [1]. The mechanisms by which CRIP1a regulates CB1R activity have not yet been identified; therefore the focus of this investigation is to examine the cellular effects of CRIP1a on CB1R signaling using neuronal N18TG2 cells stably transfected with CRIP1a over-expressing and CRIP1a knockdown constructs. Modulation of endogenous CRIP1a expression did not alter total levels of CB1R, ERK, or forskolin-activated adenylyl cyclase activity. When compared to WT cells, CRIP1a over-expression reduced basal phosphoERK levels, whereas depletion of CRIP1a augmented basal phosphoERK levels. Stimulation of phosphoERK by the CB1R agonists WIN55212-2, CP55940 or methanandamide was unaltered in CRIP1a over-expressing clones compared with WT. However, CRIP1a knockdown clones exhibited enhanced ERK phosphorylation efficacy in response to CP55940. In addition, CRIP1a knockdown clones displayed a leftward shift in CP55940-mediated inhibition of forskolin-stimulated cAMP accumulation. CB1R-mediated Gi3 and Go activation by CP99540 was attenuated by CRIP1a over-expression, but robustly enhanced in cells depleted of CRIP1a. Conversely, CP55940-mediated Gi1 and Gi2 activation was significant enhanced in cells over-expressing CRIP1a, but not in cells deficient of CRIP1a. These studies suggest a mechanism by which endogenous levels of CRIP1a modulate CB1R-mediated signal transduction by facilitating a Gi/o protein subtype preference for Gi1 and Gi2, accompanied by an overall suppression of G-protein-mediated signaling in neuronal cells.

Keywords: CB(1) receptor; CRIP1a; ERK1/2; Endocannabinoid; G protein; cAMP.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Carrier Proteins / antagonists & inhibitors
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line, Tumor
  • Cyclic AMP / metabolism
  • Cyclohexanols / pharmacology
  • GTP-Binding Protein alpha Subunits, Gi-Go / chemistry
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
  • Mice
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Phosphorylation / drug effects
  • Piperidines / pharmacology
  • Pyrazoles / pharmacology
  • RNA Interference
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / metabolism
  • Receptor, Cannabinoid, CB1 / agonists
  • Receptor, Cannabinoid, CB1 / genetics
  • Receptor, Cannabinoid, CB1 / metabolism*
  • Rimonabant
  • Signal Transduction


  • CRIP1a protein, mouse
  • Carrier Proteins
  • Cyclohexanols
  • Piperidines
  • Pyrazoles
  • RNA, Messenger
  • RNA, Small Interfering
  • Receptor, Cannabinoid, CB1
  • 3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol
  • Cyclic AMP
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • GTP-Binding Protein alpha Subunits, Gi-Go
  • Rimonabant