Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 Receptors

Agnes Gasiorek; Sarah M. Trattnig; Philip K. Ahring; Uffe Kristiansen; Bente Frølund; Kristen Frederiksen; Anders A. Jensen

doi:10.1016/j.bcp.2016.04.004

Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 Receptors

Agnes Gasiorek, Sarah M. Trattnig, Philip K. Ahring, Uffe Kristiansen, Bente Frølund, Kristen Frederiksen, Anders A. Jensen

5 Citations (Scopus)

Abstract

We have previously identified a novel class of 5-hydroxytryptamine type 3 receptor (5-HT3R) agonists sharing little structural similarity with orthosteric 5-HT3R ligands (Jørgensen et al., 2011). In the present study we have elucidated the functional characteristics and the mechanism of action of one of these compounds, trans-3-(4-methoxyphenyl)-N-(pentan-3-yl)acrylamide (TMPPAA). In electrophysiological recordings TMPPAA was found to be a highly-efficacious partial agonist equipotent with 5-HT at the 5-HT3A receptor (5-HT3AR) expressed in COS-7 cells and somewhat less potent at the receptor expressed in Xenopus oocytes. The desensitization kinetics of TMPPAA-evoked currents were very different from those mediated by 5-HT. Moreover, repeated TMPPAA applications resulted in progressive current run-down and persistent non-responsiveness of the receptor to TMPPAA, but not to 5-HT. In addition to its direct activation, TMPPAA potentiated 5-HT-mediated 5-HT3AR signalling, and the allosteric link between the two binding sites was corroborated by the analogous ability of 5-HT to potentiate TMPPAA-evoked responses. The agonism and potentiation exerted by TMPPAA at a chimeric α7-nACh/5-HT3A receptor suggested that the ligand acts through the transmembrane domain of 5-HT3AR, a notion further substantiated by its functional properties at chimeric and mutant human/murine 5-HT3ARs. A residue in the transmembrane helix 4 of 5-HT3A was identified as an important molecular determinant for the different agonist potencies exhibited by TMPPAA at human and murine 5-HT3ARs. In conclusion, TMPPAA is a novel allosteric agonist and positive allosteric modulator of 5-HT3Rs, and its aberrant signalling characteristics compared to 5-HT at the 5-HT3AR underline the potential in Cys-loop receptor modulation and activation through allosteric sites.

Original language	English
Journal	Biochemical Pharmacology
Volume	110-111
Pages (from-to)	92-108
Number of pages	17
ISSN	0006-2952
DOIs	https://doi.org/10.1016/j.bcp.2016.04.004
Publication status	Published - 15 Jun 2016

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Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 Receptors. / Gasiorek, Agnes; Trattnig, Sarah M.; Ahring, Philip K. et al.
In: Biochemical Pharmacology, Vol. 110-111, 15.06.2016, p. 92-108.

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title = "Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 Receptors",

abstract = "We have previously identified a novel class of 5-hydroxytryptamine type 3 receptor (5-HT3R) agonists sharing little structural similarity with orthosteric 5-HT3R ligands (J{\o}rgensen et al., 2011). In the present study we have elucidated the functional characteristics and the mechanism of action of one of these compounds, trans-3-(4-methoxyphenyl)-N-(pentan-3-yl)acrylamide (TMPPAA). In electrophysiological recordings TMPPAA was found to be a highly-efficacious partial agonist equipotent with 5-HT at the 5-HT3A receptor (5-HT3AR) expressed in COS-7 cells and somewhat less potent at the receptor expressed in Xenopus oocytes. The desensitization kinetics of TMPPAA-evoked currents were very different from those mediated by 5-HT. Moreover, repeated TMPPAA applications resulted in progressive current run-down and persistent non-responsiveness of the receptor to TMPPAA, but not to 5-HT. In addition to its direct activation, TMPPAA potentiated 5-HT-mediated 5-HT3AR signalling, and the allosteric link between the two binding sites was corroborated by the analogous ability of 5-HT to potentiate TMPPAA-evoked responses. The agonism and potentiation exerted by TMPPAA at a chimeric α7-nACh/5-HT3A receptor suggested that the ligand acts through the transmembrane domain of 5-HT3AR, a notion further substantiated by its functional properties at chimeric and mutant human/murine 5-HT3ARs. A residue in the transmembrane helix 4 of 5-HT3A was identified as an important molecular determinant for the different agonist potencies exhibited by TMPPAA at human and murine 5-HT3ARs. In conclusion, TMPPAA is a novel allosteric agonist and positive allosteric modulator of 5-HT3Rs, and its aberrant signalling characteristics compared to 5-HT at the 5-HT3AR underline the potential in Cys-loop receptor modulation and activation through allosteric sites.",

author = "Agnes Gasiorek and Trattnig, {Sarah M.} and Ahring, {Philip K.} and Uffe Kristiansen and Bente Fr{\o}lund and Kristen Frederiksen and Jensen, {Anders A.}",

year = "2016",

month = jun,

day = "15",

doi = "10.1016/j.bcp.2016.04.004",

language = "English",

volume = "110-111",

pages = "92--108",

journal = "Biochemical Pharmacology",

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T1 - Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 Receptors

AU - Gasiorek, Agnes

AU - Trattnig, Sarah M.

AU - Ahring, Philip K.

AU - Kristiansen, Uffe

AU - Frølund, Bente

AU - Frederiksen, Kristen

AU - Jensen, Anders A.

PY - 2016/6/15

Y1 - 2016/6/15

N2 - We have previously identified a novel class of 5-hydroxytryptamine type 3 receptor (5-HT3R) agonists sharing little structural similarity with orthosteric 5-HT3R ligands (Jørgensen et al., 2011). In the present study we have elucidated the functional characteristics and the mechanism of action of one of these compounds, trans-3-(4-methoxyphenyl)-N-(pentan-3-yl)acrylamide (TMPPAA). In electrophysiological recordings TMPPAA was found to be a highly-efficacious partial agonist equipotent with 5-HT at the 5-HT3A receptor (5-HT3AR) expressed in COS-7 cells and somewhat less potent at the receptor expressed in Xenopus oocytes. The desensitization kinetics of TMPPAA-evoked currents were very different from those mediated by 5-HT. Moreover, repeated TMPPAA applications resulted in progressive current run-down and persistent non-responsiveness of the receptor to TMPPAA, but not to 5-HT. In addition to its direct activation, TMPPAA potentiated 5-HT-mediated 5-HT3AR signalling, and the allosteric link between the two binding sites was corroborated by the analogous ability of 5-HT to potentiate TMPPAA-evoked responses. The agonism and potentiation exerted by TMPPAA at a chimeric α7-nACh/5-HT3A receptor suggested that the ligand acts through the transmembrane domain of 5-HT3AR, a notion further substantiated by its functional properties at chimeric and mutant human/murine 5-HT3ARs. A residue in the transmembrane helix 4 of 5-HT3A was identified as an important molecular determinant for the different agonist potencies exhibited by TMPPAA at human and murine 5-HT3ARs. In conclusion, TMPPAA is a novel allosteric agonist and positive allosteric modulator of 5-HT3Rs, and its aberrant signalling characteristics compared to 5-HT at the 5-HT3AR underline the potential in Cys-loop receptor modulation and activation through allosteric sites.

AB - We have previously identified a novel class of 5-hydroxytryptamine type 3 receptor (5-HT3R) agonists sharing little structural similarity with orthosteric 5-HT3R ligands (Jørgensen et al., 2011). In the present study we have elucidated the functional characteristics and the mechanism of action of one of these compounds, trans-3-(4-methoxyphenyl)-N-(pentan-3-yl)acrylamide (TMPPAA). In electrophysiological recordings TMPPAA was found to be a highly-efficacious partial agonist equipotent with 5-HT at the 5-HT3A receptor (5-HT3AR) expressed in COS-7 cells and somewhat less potent at the receptor expressed in Xenopus oocytes. The desensitization kinetics of TMPPAA-evoked currents were very different from those mediated by 5-HT. Moreover, repeated TMPPAA applications resulted in progressive current run-down and persistent non-responsiveness of the receptor to TMPPAA, but not to 5-HT. In addition to its direct activation, TMPPAA potentiated 5-HT-mediated 5-HT3AR signalling, and the allosteric link between the two binding sites was corroborated by the analogous ability of 5-HT to potentiate TMPPAA-evoked responses. The agonism and potentiation exerted by TMPPAA at a chimeric α7-nACh/5-HT3A receptor suggested that the ligand acts through the transmembrane domain of 5-HT3AR, a notion further substantiated by its functional properties at chimeric and mutant human/murine 5-HT3ARs. A residue in the transmembrane helix 4 of 5-HT3A was identified as an important molecular determinant for the different agonist potencies exhibited by TMPPAA at human and murine 5-HT3ARs. In conclusion, TMPPAA is a novel allosteric agonist and positive allosteric modulator of 5-HT3Rs, and its aberrant signalling characteristics compared to 5-HT at the 5-HT3AR underline the potential in Cys-loop receptor modulation and activation through allosteric sites.

U2 - 10.1016/j.bcp.2016.04.004

DO - 10.1016/j.bcp.2016.04.004

M3 - Journal article

C2 - 27086281

SN - 0006-2952

VL - 110-111

SP - 92

EP - 108

JO - Biochemical Pharmacology

JF - Biochemical Pharmacology

ER -

Delineation of the functional properties and the mechanism of action of TMPPAA, an allosteric agonist and positive allosteric modulator of 5-HT3 Receptors

Abstract

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