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Ca2+-dependent down-regulation of human histamine H1 receptors in Chinese hamster ovary cells.
- Source :
- Journal of Neurochemistry; Jan2018, Vol. 144 Issue 1, p68-80, 13p
- Publication Year :
- 2018
-
Abstract
- G<subscript>q/11</subscript> protein-coupled human histamine H<subscript>1</subscript> 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 Ca<superscript>2+</superscript> concentrations induced by a receptor-bypassed stimulation with ionomycin, a Ca<superscript>2+</superscript> ionophore, on the endocytosis and down-regulation of H<subscript>1</subscript> receptors in Chinese hamster ovary cells. All cellular and cell-surface H<subscript>1</subscript> receptors were detected by the binding of [<superscript>3</superscript>H]mepyramine to intact cells sensitive to the hydrophobic and hydrophilic H<subscript>1</subscript> receptor ligands, mepyramine and pirdonium, respectively. The pretreatment of cells with ionomycin markedly reduced the mepyramine- and pirdonium-sensitive binding sites of [<superscript>3</superscript>H]mepyramine, which were completely abrogated by the deprivation of extracellular Ca<superscript>2+</superscript> 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 NH<subscript>4</subscript>Cl), proteasomes (lactacystin or MG-132), and a Ca<superscript>2+</superscript>-dependent non-lysosomal cysteine protease (calpain) ( MDL28170). Since H<subscript>1</subscript> receptors were normally detected by confocal immunofluorescence microscopy with an antibody against H<subscript>1</subscript> receptors, even after the ionomycin treatment, H<subscript>1</subscript> receptors appeared to exist in a form to which [<superscript>3</superscript>H]mepyramine was unable to bind. These results suggest that H<subscript>1</subscript> receptors are apparently down-regulated by a sustained increase in intracellular Ca<superscript>2+</superscript> concentrations with no process of endocytosis and lysosomal/proteasomal degradation of receptors. [ABSTRACT FROM AUTHOR]
- Subjects :
- HISTAMINE receptors
PROTEINS
ENDOCYTOSIS
ENZYMES
PROTEIN kinases
Subjects
Details
- Language :
- English
- ISSN :
- 00223042
- Volume :
- 144
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Journal of Neurochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 126849403
- Full Text :
- https://doi.org/10.1111/jnc.14245