The human galanin receptor: ligand-binding and functional characteristics in the Bowes melanoma cell line

Abstract

The human galanin receptor has been characterized pharmacologically from the Bowes melanoma cell line. Using porcine [ 125I]galanin as the radioligand, a single population of non-interacting high-affinity binding sites ( K D = 0.05 ± 0.01 nM; B max = 13.5 ± 7 fmol/mg protein) was demonstrated. Human galanin peptide competitively inhibited the specific binding of [ 125I]galanin (IC 50 = 0.35 ± 0.13 nM) and decreased the forskolin-stimulated cAMP production (EC 50 = 0.46 ± 0.05 nM) with a maximal inhibition of 63 ± 2% at 10 −7 M. Rat and porcine galanin peptides and the chimeric peptides M15, M35, M32, M40 and C7 also dose-dependently inhibited the forskolin-stimulated cAMP production, while the fragment porcine galanin-(3–29) and [ D-Trp 2]galanin were found to be inactive. The specific binding of [ 125I]galanin was decreased in a dose-dependent manner by GTP and the cAMP response was inhibited by the pertussis toxin, suggesting the activation of a G-protein dependent process. The Bowes cell line thus appears to be a relevant tool for the study of human galanin receptor.