Human Y-79 retinoblastoma cells exhibit specific corticotropin-releasing hormone binding sites.
In this study we have identified specific binding sites for corticotropin-releasing hormone (CRH) in human Y-79 retinoblastoma cell membranes by using 125I-Tyr-ovine CRH (125I-oCRH) as radioligand. Binding at 19 degrees C was rapid with steady state being reached within 20 min, reversible and linear with membrane protein concentration. The 125I-oCRH binding was enhanced by Mg2+ and inhibited by the GTP analogue guanosine 5'-O-(3'-thiotriphosphate). Y-79 cell membranes exhibited two populations of binding sites, a high-affinity site with an apparent dissociation constant (KD) of 1 nM and a low-affinity site with an apparent KD of 500 nM. 125I-oCRH binding was completely antagonized by human/rat CRH, [Met(O)21]oCRH, alpha-helical CRH9-41, urotensin I, and sauvagine with a rank order of potency similar to that displayed by CRH receptors of other tissues. These data describe for the first time the presence of specific CRH-binding sites in retinal cells. The Y-79 cell line may therefore constitute a valuable model in which to study CRH action on retinal cells.
Olianas
M C
MC
Department of Neurosciences, University of Cagliari, Italy.
Lampis
G
G
Onali
P
P
D029845:Amphibian Proteins; D001665:Binding Sites; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism* / Q000494:pharmacology; D005134:Eye Neoplasms / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D036361:Peptide Hormones; D010455:Peptides / Q000494:pharmacology; D012175:Retinoblastoma / Q000378:metabolism* / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014579:Urotensins / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D029845:Amphibian Proteins; D036361:Peptide Hormones; D010455:Peptides; D014579:Urotensins; D014665:Vasodilator Agents; C025727:sauvagine; D003346:Corticotropin-Releasing Hormone; C029676:urotensin I