Rat cerebral cortex corticotropin-releasing hormone receptors: evidence for receptor coupling to multiple G-proteins.
The wide distribution of corticotrophin-releasing hormone (CRH) receptors in brain and periphery appear to be important in integrating the responses of the brain, endocrine and immune systems to physiological, psychological and immunological stimuli. The type 1 receptors are highly expressed throughout the cerebral cortex, a region involved in cognitive function and modulation of stress responses, where they are coupled to the adenylyl cyclase system. Using techniques that analyse receptor-mediated guanine-nucleotide binding protein (G-proteins) activation, we recently demonstrated that expressed type 1alpha CRH receptors are capable of activating multiple G-proteins, which suggests that CRH can regulate multiple signalling pathways. In an effort to characterize the intracellular signals generated by CRH in the rat cerebral cortex we sought to identify G-proteins activated by CRH in a physiological membrane environment. Rat cerebral cortical membrane suspensions were analysed for the ability of CRH to stimulate incorporation of [alpha-32P]-GTP-gamma-azidoanilide to various G-protein alpha-chains. Our results show that CRH receptors are coupled to and activate at least five different G-proteins (Gs, Gi, Gq/11, Go and Gz) with subsequent stimulation of at least two intracellular signalling cascades. In addition, the photoaffinity experiments indicated that the CRH receptors preferentially activate the 45 kDa form of the Gs alpha-protein. This data may help elucidate the intracellular signalling pathways mediating the multiple actions of CRH especially under different physiological conditions.
Grammatopoulos
D K
DK
Sir Quinton Hazell Molecular Medicine Research Centre, Department of Biological Sciences, The University of Warwick, Coventry, UK. chdg@dna.bio.warwick.ac.uk
Randeva
H S
HS
Levine
M A
MA
Kanellopoulou
K A
KA
Hillhouse
E W
EW
D000262:Adenylyl Cyclases / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001386:Azides / Q000737:chemistry; D015153:Blotting, Western; D001923:Brain Chemistry; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000737:chemistry / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000737:chemistry; D015151:Immunoblotting; D008297:Male; D019920:Photoaffinity Labels; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D018019:Receptors, Corticotropin-Releasing Hormone / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
D001386:Azides; D019920:Photoaffinity Labels; D018019:Receptors, Corticotropin-Releasing Hormone; C031907:GTP gamma-4-azidoanilide; D006160:Guanosine Triphosphate; D003346:Corticotropin-Releasing Hormone; D019204:GTP-Binding Proteins; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases