PSD-95 regulates CRFR1 localization, trafficking and β-arrestin2 recruitment

• Published in: Cellular signalling 2016-05, Vol.28 (5), p.531-540
• Main Authors: Dunn, Henry A., Chahal, Harpreet S., Caetano, Fabiana A., Holmes, Kevin D., Yuan, George Y., Parikh, Ruchi, Heit, Bryan, Ferguson, Stephen S.G.
• Format: Article
• Language: English
• Subjects: Animals; Arrestin; beta-Arrestin 2 - metabolism; Cells, Cultured; Cellular; CRFR1; Cyclic AMP - metabolism; Disks; Disks Large Homolog 4 Protein; Endocytosis; Extracellular Signal-Regulated MAP Kinases - metabolism; GPCR; Guanylate Kinases - metabolism; HEK293 Cells; Humans; Illnesses; Membrane Proteins - metabolism; Mice; Moods; PDZ; Position (location); Post-Synaptic Density - metabolism; Protein Interaction Domains and Motifs; Protein Transport; PSD-95; Receptors; Receptors, Corticotropin-Releasing Hormone - chemistry; Receptors, Corticotropin-Releasing Hormone - metabolism; Recruitment; Signal Transduction; Signalling; Trafficking
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/j.cellsig.2016.02.013

Corticotropin-releasing factor (CRF) is a neuropeptide commonly associated with the hypothalamic–pituitary adrenal axis stress response. Upon release, CRF activates two G protein-coupled receptors (GPCRs): CRF receptor 1 (CRFR1) and CRF receptor 2 (CRFR2). Although both receptors contribute to mood regulation, CRFR1 antagonists have demonstrated anxiolytic and antidepressant-like properties that may be exploited in the generation of new pharmacological interventions for mental illnesses. Previous studies have demonstrated CRFR1 capable of heterologously sensitizing serotonin 2A receptor (5-HT2AR) signaling: another GPCR implicated in psychiatric disease. Interestingly, this phenomenon was dependent on Postsynaptic density 95 (PSD-95)/Disc Large/Zona Occludens (PDZ) interactions on the distal carboxyl termini of both receptors. In the current study, we demonstrate that endogenous PSD-95 can be co-immunoprecipitated with CRFR1 from cortical brain homogenate, and this interaction appears to be primarily via the PDZ-binding motif. Additionally, PSD-95 colocalizes with CRFR1 within the dendritic projections of cultured mouse neurons in a PDZ-binding motif-dependent manner. In HEK 293 cells, PSD-95 overexpression inhibited CRFR1 endocytosis, whereas PSD-95 shRNA knockdown enhanced CRFR1 endocytosis. Although PSD-95 does not appear to play a significant role in CRF-mediated cAMP or ERK1/2 signaling, PSD-95 was demonstrated to suppress β-arrestin2 recruitment: providing a potential mechanism for PSD-95's inhibition of endocytosis. In revisiting previously documented heterologous sensitization, PSD-95 shRNA knockdown did not prevent CRFR1-mediated enhancement of 5-HT2AR signaling. In conclusion, we have identified and characterized a novel functional relationship between CRFR1 and PSD-95 that may have implications in the design of new treatment strategies for mental illness. •CRFR1 and PSD-95 have both been linked to mental illness and psychiatric disease.•Endogenous CRFR1 and PSD-95 interact in cortical mouse brain.•PDZ interactions promote synaptic targeting of CRFR1 to PSD-95 compartment.•PSD-95 suppresses CRFR1 endocytosis and βarrestin-2 recruitment.•PSD-95 is not independently responsible for CRFR1 crosstalk with 5-HT2AR.