title: CRF binding protein facilitates the presence of CRF type 2α receptor on the cell surface.
abstract: Corticotropin releasing factor binding protein (CRF-BP) was originally recognized as CRF sequestering protein. However, its differential subcellular localization in different brain nuclei suggests that CRF-BP may have additional functions. There is evidence that CRF-BP potentiates CRF and urocortin 1 actions through CRF type 2 receptors (CRF2R). CRF2R is a G protein-coupled receptor (GPCR) that is found mainly intracellularly as most GPCRs. The access of GPCRs to the cell surface is tightly regulated by escort proteins. We hypothesized that CRF-BP binds to CRF2R, exerting an escort protein role. We analyzed the colocalization of CRF-BP and CRF2R in cultured rat mesencephalic neurons, and the localization and interaction of heterologous expressed CRF-BP and CRF2αR in yeast, human embryonic kidney 293, and rat pheochromocytoma 12 cells. Our results showed that CRF-BP and CRF2R naturally colocalize in the neurites of cultured mesencephalic neurons. Heterologous expression of each protein showed that CRF-BP was localized mainly in secretory granules and CRF2αR in the endoplasmic reticulum. In contrast, CRF-BP and CRF2αR colocalized when both proteins are coexpressed. Here we show that CRF-BP physically interacts with the CRF2αR but not the CRF2βR isoform, increasing CRF2αR on the cell surface. Thus, CRF-BP emerges as a GPCR escort protein increasing the understanding of GPCR trafficking.
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, 8331150 Santiago, Chile.
authors.forename: Paula G
authors.initials: PG
authors.lastname: Slater
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, 8331150 Santiago, Chile.
authors.forename: Cledi A
authors.initials: CA
authors.lastname: Cerda
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, 8331150 Santiago, Chile.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Pereira
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, 8331150 Santiago, Chile.
authors.forename: María E
authors.initials: ME
authors.lastname: Andrés
authors.affiliation: Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, 8331150 Santiago, Chile kgysling@bio.puc.cl.
authors.forename: Katia
authors.initials: K
authors.lastname: Gysling
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D016716:PC12 Cells; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: C101531:CRF receptor type 2; D002352:Carrier Proteins; D018019:Receptors, Corticotropin-Releasing Hormone; C067133:corticotropin releasing factor-binding protein
keywords: CRH; accessory protein; escort protein; protein interactions