Insulin induces internalization of the 5-HT2A receptor expressed in HEK293 cells.
To visualize the 5-hydroxytryptamine2A (5-HT2A) receptor, we developed a 5-HT2A receptor fused with yellow fluorescent protein (5-HT2A-YFP) and expressed this receptor in HEK293 cells. In 5-HT2A-YFP-expressing cells, but not in YFP-expressing or non-expressing cells, 5-HT induced a transient increase in the intracellular Ca(2+) concentration (Ca(2+) transient) in the Fluo 3 assay, suggesting that 5-HT2A-YFP possesses a function similar to the wild-type 5-HT2A receptor. Interestingly, not only 5-HT but also insulin induced the internalization of 5-HT2A-YFP. Insulin also inhibited the 5-HT-induced Ca(2+) transient. Genistein, an inhibitor of tyrosine kinase, blocked these insulin effects. Our results provide the first evidence that insulin receptor signaling via tyrosine kinase activation induces internalization of the plasma membrane 5-HT2A receptor, and demonstrate crosstalk between the 5-HT2A receptor and the insulin receptor.
First Department of Pharmacology, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, Yoshino, Nobeoka 882-8508, Japan.
Masamichi
M
Ohkura
Naoko
N
Tanaka
Hideyuki
H
Kobayashi
Akihiko
A
Wada
Junichi
J
Nakai
Ryuichi
R
Yamamoto
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D021381:Protein Transport / Q000187:drug effects; D044402:Receptor, Serotonin, 5-HT2A / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012701:Serotonin / Q000494:pharmacology; D013997:Time Factors
D001426:Bacterial Proteins; D007328:Insulin; D008164:Luminescent Proteins; D044402:Receptor, Serotonin, 5-HT2A; D011993:Recombinant Fusion Proteins; C054562:yellow fluorescent protein, Bacteria; D012701:Serotonin; D002118:Calcium