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Borroto-Escuela D.O.,Karolinska Institutet | Narvaez M.,University of Malaga | Oflijan J.,University of Tartu | Agnati L.F.,IRCCS Lido Venice | And 2 more authors.
Biochemical and Biophysical Research Communications | Year: 2013

New findings show that neurotrophic and antidepressant effects of 5-HT in brain can, in part, be mediated by activation of the 5-HT1A receptor protomer in the hippocampal and raphe FGFR1-5-HT1A heteroreceptor complexes enhancing the FGFR1 signaling. The dynamic agonist modulation of the FGFR1-5-HT1A heteroreceptor complexes and their recruitment of β-arrestin is now determined in cellular models with focus on its impact on 5-HT1AR and FGFR1 homodimerization in the heteroreceptor complexes based on BRET2 assays. The findings show that coagonist treatment with 8-OH-DPAT and FGF2 but not treatment with the 5-HT1A agonist alone markedly increases the BRETmax values and significantly reduces the BRET50 values of 5HT1A homodimerization. The effects of FGF2 or FGF20 with or without the 5-HT1A agonist were also studied on the FGFR1 homodimerization of the heteroreceptor complexes. FGF2 produced a marked and rapid increase in FGFR1 homodimerization which partially declined over a 10 min period. Cotreatment with FGF2 and 5-HT1A agonist blocked this decline in FGFR1 homodimerization. Furthermore, FGF2 alone produced a small increase in the BRET2 signal from the 5-HT1A-β-arrestin2 receptor-protein complex which was additive to the marked effect of 8-OH-DPAT alone. Taken together, the participation of 5-HT1A and FGFR1 homodimers and recruitment of β-arrestin2 was demonstrated in the FGFR1-5-HT1A heteroreceptor complexes upon agonist treatments. © 2013 Elsevier Inc. All rights reserved. Source

Borroto-Escuela D.O.,Karolinska Institutet | Craenenbroeck K.V.,Ghent University | Romero-Fernandez W.,Karolinska Institutet | Guidolin D.,University of Padua | And 6 more authors.
Biochemical and Biophysical Research Communications | Year: 2011

Dopamine D2 and D4 receptors partially codistribute in the dorsal striatum and appear to play a fundamental role in complex behaviors and motor function. The discovery of D2R-D4.xR (D4.2R, D4.4R or D4.7R) heteromers has been made in cellular models using co-immunoprecipitation, in situ Proximity Ligation Assays and BRET1 techniques with the D2R and D4.7R receptors being the least effective in forming heteromers. Allosteric receptor-receptor interactions in D2R-D4.2R and D2R-D4.4 R heteromers were observed using the MAPK assays indicating the existence of an enhancing allosteric receptor-receptor interaction in the corresponding heteromers between the two orthosteric binding sites. The bioinformatic predictions suggest the existence of a basic set of common triplets (ALQ and LRA) in the two participating receptors that may contribute to the receptor-receptor interaction interfaces. © 2010 Elsevier Inc. Source

Fuxe K.,Karolinska Institutet | Borroto-Escuela D.O.,Karolinska Institutet | Romero-Fernandez W.,Karolinska Institutet | Ciruela F.,University of Barcelona | And 4 more authors.
Brain Research | Year: 2012

This article is focused on understanding the mechanisms for the interactions between the central catecholamine (CA) and oxytocin (OXY) neurons and their relevance for brain function especially social behaviour in the field of pair bonding. Such a topic is analysed under two perspectives namely the intercellular communication modes between CA and OXT neurons and the molecular integrative mechanisms at the plasma membrane level between their respective decoding systems. As a matter of fact, recent observations strongly indicate a major role of volume transmission and receptor-receptor interactions in the CA/OXT neuron interplay in the brain control of social behaviour and pair bonding. This article is part of a Special Issue entitled: Brain Integration. © 2012 Elsevier B.V. All rights reserved. Source

Borroto-Escuela D.O.,Karolinska Institutet | Ravani A.,University of Ferrara | Tarakanov A.O.,Russian Academy of Sciences | Brito I.,Karolinska Institutet | And 6 more authors.
Biochemical and Biophysical Research Communications | Year: 2013

Biochemical, histochemical and coimmunoprecipitation experiments have indicated the existence of antagonistic dopamine D2 (D2R) and neurotensin 1 (NTS1R) receptor-receptor interactions in the dorsal and ventral striatum indicating a potential role of these receptor-receptor interactions in Parkinson's disease and schizophrenia. By means of Bioluminiscence Resonance energy transfer (BRET2) evidence has for the first time been obtained in the current study for the existence of both D2LR/NTS1R and D2SR/NTS1R heteromers in living HEK293T cells. Through confocal laser microscopy the NTS1RGFP2 and D2RYFP were also shown to be colocated in the plasma membrane of these cells. A bioinformatic analysis suggests the existence of a basic set of three homology protriplets (TVM, DLL and/or LRA) in the two participating receptors which may contribute to the formation of the D2R/NTS1R heteromers by participating in guide-clasp interactions in the receptor interface. The CREB reporter gene assay indicated that the neurotensin receptor agonist JMV 449 markedly reduced the potency of the D2R like agonist quinpirole to inhibit the forskolin induced increase of the CREB signal. In contrast, the neurotensin agonist was found to markedly increase the quinpirole potency to activate the MAPK pathway as also studied with luciferase reporter gene assay measuring the degree of SRE activity as well as with ERK1/2 phosphorylation assays. These dynamic changes in D2R signaling produced by the neurotensin receptor agonist may involve antagonistic allosteric receptor-receptor interactions in the D2LR-NTS1R heteromers at the plasma membrane level (CREB pathway) and synergistic interactions in PKC activation at the cytoplasmatic level (MAPK pathway). © 2013 Elsevier Inc. Source

Fuxe K.,Karolinska Institutet | Borroto-Escuela D.O.,Karolinska Institutet | Tarakanov A.,Russian Academy of Sciences | Fernandez W.R.,Karolinska Institutet | And 13 more authors.
Neurology Psychiatry and Brain Research | Year: 2013

The major difference of synaptic transmission vs volume transmission (VT) is about the channels which are private in synaptic transmission (axons and terminals) but diffuse in VT represented by the channel plexus of the extracellular space and the CSF. There exist different forms of VT: extrasynatic, long distance, CSF and roamer type VT, the last one mediated via microvesicles (extracellular vesicles). Interleukin-1β (IL-1β) may produce inflammation and sickness behavior via long distance and CSF VT. The balance and integration of VT and synaptic transmission through receptor-receptor interactions in heteroreceptor complexes appears crucial for CNS communication and of high relevance for psychiatric diseases like schizophrenia, depression, cocaine addiction and anxiety. The allosteric receptor-receptor mechanism causes a marked rise of the repertoire of GPCR recognition, pharmacology, trafficking and signaling of the participating receptor protomers. We have introduced the moonlighting concept into the GPCR heteromer field, since GPCR protomers can change their function through the allosteric receptor-receptor interactions. This is achieved through changes in recognition, G protein selectivity, and signaling via other proteins involving, e.g., a switch from G proteins to β-arrestin through conformational changes in single or several strands of amino acids. It is of substantial interest to understand the role of altered receptor-receptor interactions as a mechanism for how neuroinflammatory processes can contribute to mental dysfunctions. It is hypothesized that chemokine and cytokine receptors may directly form heteroreceptor complexes with neuronal receptors known to be dysfunctional in schizophrenia and targets for antipsychotic drugs. Based on the current bioinformatic analysis performed we can postulate that chemokine receptor CXCR4 may directly interact with GABAB2 and NR2A subunits of the NMDAR, chemokine receptor CCR2 with NMDAR, GABAB1 subunit and GABAAR and cytokine receptor IL1R2 with GABAB1 subunit and NMDAR, all known to be involved in schizophrenia. Through the allosteric receptor-receptor interactions in such pathological heteroreceptor complexes the neuronal NMDA, GABAA and GABAB protomers may change their function (moonlighting) in neuronal networks of the brain. This process in neuroinflammation can contribute to positive, negative and/or cognitive symptoms of schizophrenia in line with the mild encephalitis hypothesis of schizophrenia. Neuroinflammation in schizophrenia may also disturb the integrative process of synaptic and volume transmission signals in glutamate synapses by altering kynurenines in the mammalian brain. © 2013 Elsevier GmbH. Source

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