Ca2+/calmodulin-mediated regulation of the desensitizing process in G protein-coupled histamine H1 receptor-mediated Ca2+ responses in human U373 MG astrocytoma cells

Histamine H1 receptor expression has been reported to change in disorders such as allergic rhinitis, autoimmune myocarditis, rheumatoid arthritis and atherosclerosis. Here we report the isolation and characterization of genomic clones containing the 5´ flanking (regulatory) region of the human histamine H1 receptor gene. An intron of approx. 5.8 kb was identified in the 5´ untranslated region, which suggests that an entire subfamily of G-protein-coupled receptors may contain an intron immediately upstream of the start codon. The transcription initiation site was mapped by 5´ rapid amplification of cDNA ends to a region 6.2 kb upstream of the start codon. Immediately upstream of the transcription start site a fragment of 1.85 kb was identified that showed promoter activity when placed upstream of a luciferase reporter gene and transiently transfected into cells expressing the histamine H1 receptor. The promoter sequence shares a number of characteristics with the promoter sequences of other G-protein-coupled receptor encoding genes, including binding sites for several transcription factors, and the absence of TATA and CAAT sequences at the appropriate locations. The promoter sequence described here differs from that reported previously [Fukui, Fujimoto, Mizuguchi, Sakamoto, Horio, Takai, Yamada and Ito (1994) Biochem. Biophys. Res. Commun. 201, 894–901] because the reported genomic clone was chimaeric. Furthermore our study provides evidence that the 3´ untranslated region of the H1 receptor mRNA is much longer than previously accepted. Together, these findings provide a complete view of the structure of the human histamine H1 receptor gene. Both the coding region of the H1 receptor gene and its promoter region were independently mapped to chromosome 3p25.

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Faculty Opinions recommendation of The Target Residence Time of Antihistamines Determines Their Antagonism of the G Protein-Coupled Histamine H1 Receptor.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.732026759.793543299 ◽

2018 ◽

Author(s):

Robert Copeland

Keyword(s):

G Protein ◽

Residence Time ◽

H1 Receptor ◽

Histamine H1 Receptor ◽

G Protein Coupled

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Calmodulin-mediated regulation of the desensitizing process in histamine H1 receptor-mediated Ca2+ responses in human U373 MG astrocytoma cells

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)34546-9 ◽

1999 ◽

Vol 79 ◽

pp. 133

Author(s):

Shigeru Hishinuma ◽

Kazumi Ogura

Keyword(s):

H1 Receptor ◽

Histamine H1 Receptor ◽

Astrocytoma Cells

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Extracellular osmolarity modulates G protein-coupled receptor-dependent ATP release from 1321N1 astrocytoma cells

AJP Cell Physiology ◽

10.1152/ajpcell.00430.2009 ◽

2010 ◽

Vol 298 (2) ◽

pp. C386-C396 ◽

Cited By ~ 27

Author(s):

Andrew E. Blum ◽

B. Corbett Walsh ◽

George R. Dubyak

Keyword(s):

G Protein ◽

Rho Gtpase ◽

Atp Release ◽

Hypertonic Medium ◽

Hypertonic Stress ◽

Hypotonic Stress ◽

Astrocytoma Cells ◽

Gtpase Activation ◽

G Protein Coupled ◽

1321N1 Astrocytoma

We previously reported that ATP release from 1321N1 human astrocytoma cells could be stimulated either by activation of G protein-coupled receptors (GPCR) or by hypotonic stress. Cheema et al. (Cheema TA, Ward CE, Fisher SK. J Pharmacol Exp Ther 315: 755–763, 2005) have demonstrated that thrombin activation of protease-activated receptor 1 (PAR1) in 1321N1 cells and primary astrocytes acts synergistically with hypotonic stress to gate the opening of volume-sensitive organic osmolyte and anion channels (VSOAC) and that hypertonic stress strongly inhibits PAR1 gating of VSOAC. We tested the hypothesis that a VSOAC-type permeability might comprise a GPCR-regulated pathway for ATP export by determining whether PAR1-sensitive ATP release from 1321N1 cells is similarly potentiated by hypotonicity but suppressed by hypertonic conditions. Strong hypotonic stress by itself elicited ATP release and positively modulated the response to thrombin. Thrombin-dependent ATP release was also potentiated by mild hypotonic stress that by itself did not stimulate ATP export. Notably, PAR1-sensitive ATP export was greatly inhibited in hypertonic medium. Neither the potency nor efficacy of thrombin as an activator of proximal PAR1 signaling was affected by hypotonicity or hypertonicity. 1,9-Dideoxyforskolin and carbenoxolone similarly attenuated PAR1-dependent ATP release and suppressed the PAR1-independent ATP elicited by strong hypotonic stress. Probenecid attenuated PAR1-stimulated ATP release under isotonic but not mild hypotonic conditions and had no effect on PAR1-independent release stimulated by strong hypotonicity. PAR1-dependent ATP export under all osmotic conditions required concurrent signaling by Ca2+ mobilization and Rho-GTPase activation. In contrast, PAR1-independent ATP release triggered by strong hypotonicity required neither of these intracellular signals. Thus, we provide the new finding that GPCR-regulated ATP release from 1321N1 astrocytoma cells is remarkably sensitive to both positive and negative modulation by extracellular osmolarity. This supports a model wherein GPCR stimulation and osmotic stress converge on an ATP release pathway in astrocytes that exhibits several features of VSOAC-type channels.

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Analysis of Missense Variants in the Human Histamine Receptor Family Reveals Increased Constitutive Activity of E4106.30×30K Variant in the Histamine H1 Receptor

International Journal of Molecular Sciences ◽

10.3390/ijms22073702 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3702

Author(s):

Xiaoyuan Ma ◽

Marta Arimont Segura ◽

Barbara Zarzycka ◽

Henry F. Vischer ◽

Rob Leurs

Keyword(s):

G Protein ◽

Missense Variant ◽

Histamine Receptor ◽

Structural Basis ◽

Constitutive Activity ◽

Wild Type ◽

H1 Receptor ◽

Histamine H1 Receptor ◽

Missense Variants ◽

Receptor Family

The Exome Aggregation Consortium has collected the protein-encoding DNA sequences of almost 61,000 unrelated humans. Analysis of this dataset for G protein-coupled receptor (GPCR) proteins (available at GPCRdb) revealed a total of 463 naturally occurring genetic missense variations in the histamine receptor family. In this research, we have analyzed the distribution of these missense variations in the four histamine receptor subtypes concerning structural segments and sites important for GPCR function. Four missense variants R1273.52×52H, R13934.57×57H, R4096.29×29H, and E4106.30×30 K, were selected for the histamine H1 receptor (H1R) that were hypothesized to affect receptor activity by interfering with the interaction pattern of the highly conserved D(E)RY motif, the so-called ionic lock. The E4106.30×30 K missense variant displays higher constitutive activity in G protein signaling as compared to wild-type H1R, whereas the opposite was observed for R1273.52×52H, R13934.57×57H, and R4096.29×29H. The E4106.30×30 K missense variant displays a higher affinity for the endogenous agonist histamine than wild-type H1R, whereas antagonist affinity was not affected. These data support the hypothesis that the E4106.30×30 K mutation shifts the equilibrium towards active conformations. The study of these selected missense variants gives additional insight into the structural basis of H1R activation and, moreover, highlights that missense variants can result in pharmacologically different behavior as compared to wild-type receptors and should consequently be considered in the drug discovery process.

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