Radioligand binding and functional characterization of recombinant human NmU1 and NmU2 receptors stably expressed in clonal human embryonic kidney-293 cells

Pharmacology. 2004 Sep;72(1):33-41. doi: 10.1159/000078630.


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.

MeSH terms

  • Binding Sites
  • Cells, Cultured
  • Clone Cells
  • Humans
  • Kidney / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Membrane Proteins / physiology
  • Oligonucleotide Array Sequence Analysis
  • Radioligand Assay
  • Receptors, Neurotransmitter / genetics
  • Receptors, Neurotransmitter / metabolism*
  • Receptors, Neurotransmitter / physiology
  • Signal Transduction


  • Membrane Proteins
  • Receptors, Neurotransmitter
  • neuromedin U receptor