A single‐point mutation (Ala280Val) in the third intracellular loop alters the signalling properties of the human histamine H3 receptor stably expressed in CHO‐K1 cells. (15th August 2013)

• Record Type: Journal Article
• Authors: Flores‐Clemente, Cecilia; Osorio‐Espinoza, Angélica; Escamilla‐Sánchez, Juan; Leurs, Rob; Arias, Juan‐Manuel; Arias‐Montaño, José‐Antonio
• Is Part Of: British journal of pharmacology. Volume 170:Number 1(2013:Sep.)
• Page Start: 127
• Page End: 135
• Publication Date: 2013-08-15
• Subjects: Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/bph.12257
• Languages: English
• ISSNs: 0007-1188

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bph12257-sec-0001" sec-type="section"> <title>Background and Purpose</title> <p>An alanine to valine exchange at amino acid position 280 (A280V) in the third intracellular loop of the human histamine H<sub>3</sub> receptor was first identified in a patient suffering from Shy–Drager syndrome and later reported as a risk factor for migraine. Here, we have compared the pharmacological and signalling properties of wild‐type (hH<sub>3</sub>R<sub>WT</sub>) and A280V mutant (hH<sub>3</sub>R<sub>A280V</sub>) receptors stably expressed in CHO‐K1 cells.</p> </sec> <sec id="bph12257-sec-0002" sec-type="section"> <title>Experimental Approach</title> <p>The hH<sub>3</sub>R<sub>A280V</sub> cDNA was created by overlapping extension PCR amplification. Receptor expression and affinity were assessed by radioligand (N‐α‐[methyl‐<sup>3</sup>H]‐histamine) binding to cell membranes, and receptor function by the inhibition of forskolin‐induced cAMP accumulation and stimulation of ERK1/2 phosphorylation in intact cells, as well as stimulation of [<sup>35</sup>S]‐GTPγS binding to cell membranes.</p> </sec> <sec id="bph12257-sec-0003" sec-type="section"> <title>Key Results</title> <p>Both receptors were expressed at similar levels with no significant differences in their affinities for H<sub>3</sub> receptor ligands. Upon activation the hH<sub>3</sub>R<sub>WT</sub> was significantly more efficacious to inhibit forskolin‐induced cAMP accumulation and to stimulate [<sup>35</sup>S]‐GTPγS binding, with no difference in pEC<sub>50</sub> estimates. The hH<sub>3</sub>R<sub>WT</sub> was also more efficacious to stimulate ERK1/2 phosphorylation, but this difference was not significant. The inverse agonist ciproxifan was more efficacious at hH<sub>3</sub>R<sub>WT</sub> to reduce [<sup>35</sup>S]‐GTPγS binding but, for both receptors, failed to enhance forskolin‐induced cAMP accumulation.</p> </sec> <sec id="bph12257-sec-0004" sec-type="section"> <title>Conclusions and Implications</title> <p>The A280V mutation reduces the signalling efficacy of the human H<sub>3</sub> receptor. This effect may be relevant to the pathophysiology of disorders associated with the mutation.</p> </sec> <sec id="bph12257-sec-5001" sec-type="relatedArticles"> <title>Linked Articles</title> <p>This article is part of a themed issue on Histamine Pharmacology Update. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2013.170.issue‐1</p> </sec> </abstract>