LACK OF RAPID DESENSITIZATION OF CA2+ RESPONSES IN TRANSFECTED CHO CELLS EXPRESS

2020-03-26 13:08:24

Ca2 receptor peptide neurotensin desensitization

责任者: HERMANS, E;GAILLY, P;GILLIS, JM;OCTAVE, JN;MALOTEAUX, JM 单位: UNIV CATHOLIQUE LOUVAIN,DEPT PHYSIOL,B-1200 BRUSSELS,BELGIUM. 来源出处: JOURNAL OF NEUROCHEMISTRY, v 64, JUN 1995, p 2518- 2525 摘要: Transfected Chinese hamster ovary cells were used as a model for the study of the desensitization of the neurotensin receptor at the second messenger level. Stimulation with nanomolar concentrations of neurotensin elicited rapid rises in the cytosolic calcium concentration ([Ca2+](i)), which remained elevated throughout the peptide application. A significant response was already detected with neurotensin concentrations as low as 0.01 nM. This high efficiency of neurotensin in mediating this calcium response contrasts with the nanomolar affinity of the peptide for its receptor measured in binding experiments. Evidence indicated that the initial elevation of the [Ca2+](i) resulted from release of Ca2+ from intracellular stores, whereas the sustained response involved an influx of extracellular origin. Return to the basal level was only reached after extensive washing of the peptide or its displacement with the neurotensin receptor antagonist SR48692. After washing, further stimulations were still able to mediate an increase in the [Ca2+](i), indicating an apparent absence of rapid desensitization of the intracellular signaling pathway that mediates calcium mobilization. In contrast with this absence of response desensitization, the neurotensin receptors were found to internalize after stimulation with the peptide. This internalization was maximal after 30 min and accounted for similar to 70% of the number of neurotensin binding sites located at the cell surface. These results indicate that despite the functional properties of the rat neurotensin receptor present in Chinese hamster ovary cells after transfection, the intracellular signaling pathway triggered by stimulation with neurotensin seems to be resistant to desensitization. This might be related to the high efficiency of the intracellular signaling pathway coupled to the neurotensin receptor observed in these cells. A possible absence of desensitization of the neurotensin receptor itself is also discussed. 关键词: NEUROTENSIN; RECEPTOR; DESENSITIZATION; INTERNALIZATION; CALCIUM; SIGNALING SIGNALING; CALCIUM-CHANNEL BLOCKERS; BLASTOMA CLONE N1E-115; CYCLIC-AMP FORMATION; INOSITOL TRISPHOSPHATE; FUNCTIONAL EXPRESSION; DOPAMINE RELEASE; C INOSITOL TRISPHOSPHATE; FUNCTIONAL EXPRESSION; DOPAMINE RELEASE; C ACTIVATION; NEUROMEDIN-N; HT29 CELLS; MOBILIZATION ACTIVATION; NEUROMEDIN-N; HT29 CELLS; MOBILIZATION