Details

Autor(en) / Beteiligte

• Blume, Lawrence C.
• Leone‐Kabler, Sandra
• Luessen, Deborah J.
• Marrs, Glen S.
• Lyons, Erica
• Bass, Caroline E.
• Chen, Rong
• Selley, Dana E.
• Howlett, Allyn C.

Titel

Cannabinoid receptor interacting protein suppresses agonist‐driven CB1 receptor internalization and regulates receptor replenishment in an agonist‐biased manner

Ist Teil von

• Journal of neurochemistry, 2016-11, Vol.139 (3), p.396-407

Ort / Verlag

New York: Blackwell Publishing Ltd

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Cannabinoid receptor interacting protein 1a (CRIP1a) is a CB1 receptor (CB1R) distal C‐terminus‐associated protein that modulates CB1R signaling via G proteins, and CB1R down‐regulation but not desensitization (Blume et al. [2015] Cell Signal., 27, 716–726; Smith et al. [2015] Mol. Pharmacol., 87, 747–765). In this study, we determined the involvement of CRIP1a in CB1R plasma membrane trafficking. To follow the effects of agonists and antagonists on cell surface CB1Rs, we utilized the genetically homogeneous cloned neuronal cell line N18TG2, which endogenously expresses both CB1R and CRIP1a, and exhibits a well‐characterized endocannabinoid signaling system. We developed stable CRIP1a‐over‐expressing and CRIP1a‐siRNA‐silenced knockdown clones to investigate gene dose effects of CRIP1a on CB1R plasma membrane expression. Results indicate that CP55940 or WIN55212‐2 (10 nM, 5 min) reduced cell surface CB1R by a dynamin‐ and clathrin‐dependent process, and this was attenuated by CRIP1a over‐expression. CP55940‐mediated cell surface CB1R loss was followed by a cycloheximide‐sensitive recovery of surface receptors (30–120 min), suggesting the requirement for new protein synthesis. In contrast, WIN55212‐2‐mediated cell surface CB1Rs recovered only in CRIP1a knockdown cells. Changes in CRIP1a expression levels did not affect a transient rimonabant (10 nM)‐mediated increase in cell surface CB1Rs, which is postulated to be as a result of rimonabant effects on ‘non‐agonist‐driven’ internalization. These studies demonstrate a novel role for CRIP1a in agonist‐driven CB1R cell surface regulation postulated to occur by two mechanisms: 1) attenuating internalization that is agonist‐mediated, but not that in the absence of exogenous agonists, and 2) biased agonist‐dependent trafficking of de novo synthesized receptor to the cell surface. The CB1R‐interacting protein CRIP1a functions to differentially modulate agonist‐promoted versus non‐agonist‐mediated CB1R internalization and cell surface equilibrium. Association of CRIP1a with the CB1R precludes agonist‐driven internalization via a mechanism involving β‐arrestin, clathrin and dynamin. CRIP1a also functions to fine‐tune CB1R cell surface levels through delivery of newly synthesized CB1R receptors to the plasma membrane.