Regulation of the Coupling to Different G Proteins of Rat Corticotropin-releasing Factor Receptor Type 1 in Human Embryonic Kidney 293 Cells

Abstract

The regulation of G protein activation by the rat corticotropin-releasing factor receptor type 1 (rCRFR1) in human embryonic kidney (HEK)293 (HEK-rCRFR1) cell membranes was studied. S]GTP␥S-bound G␣ q/11 revealed additional coupling to G q/11 , which also was homologously desensitized. Although G␣ q/11 coupling was PTX-insensitive, half of the sauvagine-stimulated accumulation of inositol phosphates in the cells was PTX-sensitive, suggesting involvement of G i in addition to G q/11 in the stimulation of inositol metabolism. It is concluded that CRFR1 signals through at least two different ways, one leading to G s -and G q/11 -mediated signaling steps and desensitization and another leading to G i -mediated signals without being desensitized. Furthermore, the concentrations of the stimulating ligand and GTP and desensitization may be part of a regulatory mechanism determining the actual ratio of the coupling of CRFR1 to different G proteins.The hypothalamic peptide corticotropin-releasing factor (CRF) 1 not only regulates the stress response in mammals by activation of the pituitary adrenal axis (1) but is also involved in the control of the immune response, cardiovascular, reproductive, and cognitive function, ingestive behavior, pregnancy and labor (for a review, see Refs. 2 and 3). The multiple actions of CRF are mediated by two classes of specific CRF receptors, CRFR1 (4 -6) and CRFR2 (7,8), which are encoded by unique genes and of which some variants exist, produced by alternative processing of the transcripts from each of the genes (for

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The Sequence after the Signal Peptide of the G Protein-Coupled Endothelin B Receptor Is Required for Efficient Translocon Gating at the Endoplasmic Reticulum Membrane

“…The lysate was transferred to tubes, and radioactivity was measured using a ␥ counter. For the inositol phosphate accumulation assay, the experiment was carried out with intact transiently transfected HEK 293 cells as described previously for stably transfected HEK 293 cells (Wietfeld et al, 2004). All data were analyzed using the Prism software (release 3.02).…”

The Corticotropin-releasing Factor Receptor Type 2a Contains an N-terminal Pseudo Signal Peptide

“…3 H]cAMP were purchased from PerkinElmer Life Sciences. All peptidic ligands of CRF receptors (sauvagine, urocortin I, and urocortin II) were synthesized in our laboratory (16). Lipofectamine TM 2000 and the vector pSecTag2A were purchased from Invitrogen.…”