5-hydroxytryptamine 4 receptor activation of the extracellular signal-regulated kinase pathway depends on Src activation but not on G protein or beta-arrestin signaling.
The 5-hydroxytryptamine(4) (5-HT(4)) receptors have recently emerged as key modulators of learning, memory, and cognitive processes. In neurons, 5-hydroxytryptamine(4) receptors (5-HT(4)Rs) activate cAMP production and protein kinase A (PKA); however, nothing is known about their ability to activate another key signaling pathway involved in learning and memory: the extracellular signal-regulated kinase (ERK) pathway. Here, we show that 5-HT(4)R stimulation, in primary neurons, produced a potent but transient activation of the ERK pathway. Surprisingly, this activation was mostly PKA independent. Similarly, using pharmacological, genetic, and molecular tools, we observed that 5-HT(4)Rs in human embryonic kidney 293 cells, activated the ERK pathway in a G(s)/cAMP/PKA-independent manner. We also demonstrated that other classical G proteins (G(q)/G(i)/G(o)) and associated downstream messengers were not implicated in the 5-HT(4)R-activated ERK pathway. The 5-HT(4)R-mediated ERK activation seemed to be dependent on Src tyrosine kinase and yet totally independent of beta-arrestin. Immunocytofluorescence revealed that ERK activation by 5-HT(4)R was restrained to the plasma membrane, whereas p-Src colocalized with the receptor and carried on even after endocytosis. This phenomenon may result from a tight interaction between 5-HT(4)R and p-Src detected by coimmunoprecipitation. Finally, we confirmed that the main route by which 5-HT(4)Rs activate ERKs in neurons was Src dependent. Thus, in addition to classical cAMP/PKA signaling pathways, 5-HT(4)Rs may use ERK pathways to control memory process.
Barthet
Gaël
G
Institut de Génomique Fonctionnelle, Montpellier F-34094, France.
Framery
Bérénice
B
Gaven
Florence
F
Pellissier
Lucie
L
Reiter
Eric
E
Claeysen
Sylvie
S
Bockaert
Joël
J
Dumuis
Aline
A
D000595:Amino Acid Sequence; D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D044422:Receptors, Serotonin, 5-HT4 / Q000235:genetics / Q000378:metabolism*; D000071557:beta-Arrestins; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
D019390:Arrestins; D034741:RNA, Small Interfering; D000071557:beta-Arrestins; D044422:Receptors, Serotonin, 5-HT4; D000242:Cyclic AMP; D019061:src-Family Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D019204:GTP-Binding Proteins