Pharmacological evaluation of alpha and beta human tachykinin NK(2) receptor splice variants expressed in CHO cells.
In the present study, we have investigated, by binding and functional experiments, the pharmacological profile of a new human tachykinin NK(2) receptor splice variant named beta isoform. Neurokinin A, nepadutant, SR48968 [(S)-N-methyl-N[4-(4-acetylamino-4-phenyl piperidino)-2-(3,4-dichlorophenyl) butyl]benzamide] and substance P have been tested for binding on the receptor expressed in whole CHO transfected cells. Only SR48968 binds, but with an affinity about sixfold lower in respect to the alpha isoform. Moreover, neurokinin A was unable to inhibit the [(3)H]SR48968 binding to the beta isoform up to microM concentrations. In cells expressing the human tachykinin NK(2) receptor beta isoform, contrary to those expressing the alpha isoform, natural or selective tachykinin receptor agonists (1 microM) were unable to produce a significant activation of inositol phosphate (IP) production or increase of intracellular calcium concentration [Ca(2+)](i). The recently discovered tachykinins, endokinins C and D, did not activate IP production or [Ca(2+)](i) increase in cells expressing the alpha or beta isoform of the human tachykinin NK(2) receptor. The present data indicate that the human tachykinin NK(2) receptor beta isoform is poorly or not expressed on the cell membrane surface and that it may possibly act as a regulator of tachykinin NK(2) receptor function. We cannot exclude the possibility that this receptor could interact with other presently unknown ligands.
Bellucci
Francesca
F
Pharmacology Department, Menarini Ricerche S.p.A., via Rismondo 12A, I-50131, Florence, Italy.
Meini
Stefania
S
Catalioto
Rose-Marie
RM
Catalani
Claudio
C
Giuliani
Sandro
S
Quartara
Laura
L
Giolitti
Alessandro
A
Faiella
Angela
A
Rotondaro
Luigi
L
Candenas
Maria Luz
ML
Pinto
Francisco M
FM
Maggi
Carlo Alberto
CA
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001549:Benzamides / Q000378:metabolism; D001667:Binding, Competitive / Q000187:drug effects; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007295:Inositol Phosphates / Q000096:biosynthesis; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D007457:Iodine Radioisotopes; D008969:Molecular Sequence Data; D015288:Neurokinin A / Q000378:metabolism / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000378:metabolism / Q000494:pharmacology; D010880:Piperidines / Q000378:metabolism; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011869:Radioligand Assay; D018041:Receptors, Neurokinin-2 / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology; D014162:Transfection; D014316:Tritium
D001549:Benzamides; D007295:Inositol Phosphates; D007457:Iodine Radioisotopes; C107754:MEN 11420; D010456:Peptides, Cyclic; D010880:Piperidines; D020033:Protein Isoforms; D018041:Receptors, Neurokinin-2; D014316:Tritium; D013373:Substance P; C073839:SR 48968; D015288:Neurokinin A; D002118:Calcium