Ca2+-dependent down-regulation of human histamine H1receptors in Chinese hamster ovary cells
| Autor: | Hirokazu Hatahara, Masaru Shoji, Hayato Tsukamoto, Hiroshi Komazaki, Shigeru Hishinuma, Hiroyuki Fukui |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Chinese hamster ovary cell Mepyramine Stimulation Histamine H1 receptor Endocytosis Biochemistry Molecular biology 03 medical and health sciences Cellular and Molecular Neuroscience chemistry.chemical_compound 030104 developmental biology 0302 clinical medicine chemistry Ionomycin medicine Receptor 030217 neurology & neurosurgery Histamine medicine.drug |
| Zdroj: | Journal of Neurochemistry. 144:68-80 |
| ISSN: | 0022-3042 |
| DOI: | 10.1111/jnc.14245 |
| Popis: | Gq/11 protein-coupled human histamine H1 receptors in Chinese hamster ovary cells stimulated with histamine undergo clathrin-dependent endocytosis followed by proteasome/lysosome-mediated down-regulation. In this study, we evaluated the effects of a sustained increase in intracellular Ca2+ concentrations induced by a receptor-bypassed stimulation with ionomycin, a Ca2+ ionophore, on the endocytosis and down-regulation of H1 receptors in Chinese hamster ovary cells. All cellular and cell-surface H1 receptors were detected by the binding of [3 H]mepyramine to intact cells sensitive to the hydrophobic and hydrophilic H1 receptor ligands, mepyramine and pirdonium, respectively. The pretreatment of cells with ionomycin markedly reduced the mepyramine- and pirdonium-sensitive binding sites of [3 H]mepyramine, which were completely abrogated by the deprivation of extracellular Ca2+ and partially by a ubiquitin-activating enzyme inhibitor (UBEI-41), but were not affected by inhibitors of calmodulin (W-7 or calmidazolium) and protein kinase C (chelerythrine or GF109203X). These ionomycin-induced changes were also not affected by inhibitors of receptor endocytosis via clathrin (hypertonic sucrose) and caveolae/lipid rafts (filipin or nystatin) or by inhibitors of lysosomes (E-64, leupeptin, chloroquine, or NH4 Cl), proteasomes (lactacystin or MG-132), and a Ca2+ -dependent non-lysosomal cysteine protease (calpain) (MDL28170). Since H1 receptors were normally detected by confocal immunofluorescence microscopy with an antibody against H1 receptors, even after the ionomycin treatment, H1 receptors appeared to exist in a form to which [3 H]mepyramine was unable to bind. These results suggest that H1 receptors are apparently down-regulated by a sustained increase in intracellular Ca2+ concentrations with no process of endocytosis and lysosomal/proteasomal degradation of receptors. |
| Databáze: | OpenAIRE |
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