Radioligand binding and functional characterization of recombinant human NmU1 and NmU2 receptors stably expressed in clonal human embryonic kidney-293 cells.
Neuromedin U (NmU) is a smooth muscle contracting peptide. Recently, two G-protein-coupled receptors for NmU (NmU1R and NmU2R) have been cloned having approximately 50% homology. They have distinct patterns of expression suggesting they may have different biological functions. This study provides a comprehensive characterization of both NmU receptors expressed in human embryonic kidney 293 cells. [125I]hNmU binding to the recombinant NmU receptors was rapid, saturable, of high affinity and to a single population of binding sites. Exposure of these cells to NmU isopeptides resulted in an increase in intracellular [Ca2+]i release (EC50 value of 0.50 +/- 0.10 nmol/l) and inositol phosphate formation (EC50 1.6 +/- 0.2 and 1.50 +/- 0.4 nmol/l for NmU1R and NmU2R respectively). Furthermore, hNmU inhibited forskolin (3 micromol/l)-stimulated accumulation of cAMP in intact HEK-293 cells expressing either NmU1R or NmU2R. The inhibitory effect was significant for the cells expressing NmU2R with IC50 value of 0.80 +/- 0.21 nmol/l. In summary, both NmU1R and NmU2R in HEK-293 cells have similar signaling capability.
Vascular Biology, Cardiovascular and Urogenital Center of Excellence for Drug Discovery, GlaxoSmithKline, King of Prussia, PA 19406-0939, USA. nambi_aiyar-1@gsk.com
Nambi
N
Aiyar
Jyoti
J
Disa
James J
JJ
Foley
Peter T
PT
Buckley
William E
WE
Wixted
Mark
M
Pullen
Usman
U
Shabon
Edward
E
Dul
Philip G
PG
Szekeres
Nabil A
NA
Elshourbagy
Henry M
HM
Sarau
Edward
E
Appelbaum
Jane
J
Bolaky
D001665:Binding Sites; D002478:Cells, Cultured; D002999:Clone Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis; D011869:Radioligand Assay; D017981:Receptors, Neurotransmitter / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction
D008565:Membrane Proteins; D017981:Receptors, Neurotransmitter; C082444:neuromedin U receptor