Multiple interaction sites of galnon trigger its biological effects.
Galnon was first reported as a low molecular weight non-peptide agonist at galanin receptors [Saar et al. (2002) Proc. Natl. Acad. Sci. USA 99, 7136-7141]. Following its systemic administration, this synthetic ligand affected a range of important physiological processes including appetite, seizures and pain. Physiological activity of galnon could not be explained solely by the activation of the three known galanin receptors, GalR1, GalR2 and GalR3. Consequently, it was possible that galnon generates its manifold effects by interacting with other signaling pathway components, in addition to via GalR1-3. In this report, we establish that galnon: (i) can penetrate across the plasma membrane of cells, (ii) can activate intracellular G-proteins directly independent of receptor activation thereby triggering downstream signaling, (iii) demonstrates selectivity for different G-proteins, and (iiii) is a ligand to other G-protein coupled receptors (GPCRs) in addition to via GalR1-3. We conclude that galnon has multiple sites of interaction within the GPCR signaling cascade which mediate its physiological effects.
Florén
Anders
A
Department of Neurochemistry, Stockholm University, Sweden.
Sollenberg
Ulla
U
Lundström
Linda
L
Zorko
Matjaz
M
Stojan
Jure
J
Budihna
Metka
M
Wheatley
Mark
M
Martin
Negin P
NP
Kilk
Kalle
K
Mazarati
Andrey
A
Bartfai
Tamas
T
Lindgren
Maria
M
Langel
Ulo
U
D000818:Animals; D002460:Cell Line; D003331:Coronary Vessels / Q000378:metabolism; D003374:Coumarins / Q000737:chemistry / Q000378:metabolism*; D006224:Cricetinae; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D037342:Pertussis Toxin / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D044088:Receptors, Galanin / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013552:Swine
C456547:7-((9-fluorenylmethoxycarbonyl)cyclohexylalanyllysyl)amino-4-methylcoumarin; D003374:Coumarins; D008024:Ligands; D020033:Protein Isoforms; D044088:Receptors, Galanin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D037342:Pertussis Toxin; D019204:GTP-Binding Proteins