Isolation and Detection of G Protein-Coupled Receptor (GPCR) Heteroreceptor Complexes in Rat Brain Synaptosomal Preparation Using a Combined Brain Subcellular Fractionation/Co-immunoprecipitation (Co-IP) Procedures

none13sìThe isolation and characterization of GPCR heteroreceptor complexes, specially those present at the central nervous system, are of crucial relevance for the understanding of the molecular mechanisms behind several mental and neurodegenerative disorders. The existence of homo- and heteroreceptor complexes with allosteric receptor-receptor interactions increases the diversity of receptor function including recognition, trafficking, and signaling. This phenomenon increases our understanding of how brain function is altered through molecular integration of receptor signals. An alteration in specific heteroreceptor complexes or their neuronal localization is considered to have a role in the pathogenic mechanisms that lead to mental and neurological diseases, including drug addiction, depression, Parkinson’s disease, and schizophrenia. Therefore, it is fundamental to understand the appropriate localization and synaptic clustering of these GPCR heteroreceptor complexes. This chapter represents a workflow for the analysis of GPCR heteroreceptor complexes by means of combined use of differential centrifugation/coimmunoprecipitation in rat brain tissue. The combination of differential centrifugation/coimmunoprecipitation allows the separation and detection of GPCR heteroreceptor complexes present at synaptic sites from those found in intracellular compartments and vesicular pools. It is a reproducible protocol and produces reliable quantitative data.restrictedDasiel O. Borroto-Escuela, Manuel Narvaez, Martina Zannoni, Chiara Contri, Minerva Crespo-Ramírez, Michael di Palma, Patrizia Ambrogini, Daily Y. Borroto-Escuela, Ismel Brito, Mariana Pita-Rodríguez, Ismael Valladolid-Acebes, Miguel Pérez de la Mora, and Kjell FuxeBorroto-Escuela, Dasiel O.; Narvaez, Manuel; Zannoni, Martina; Contri, Chiara; Crespo-Ramírez, Minerva; DI PALMA, Michael; Ambrogini, Patrizia; Borroto-Escuela, Daily Y.; Brito, Ismel; Pita-Rodríguez, Mariana; Valladolid-Acebes, Ismael; Pérez de la Mora, Miguel; Kjell Fuxe, An

The G Protein-Coupled Receptor Heterodimer Network (GPCR-HetNet) and Its Hub Components.

G protein-coupled receptors (GPCRs) oligomerization has emerged as a vital characteristic of receptor structure. Substantial experimental evidence supports the existence of GPCR-GPCR interactions in a coordinated and cooperative manner. However, despite the current development of experimental techniques for large-scale detection of GPCR heteromers, in order to understand their connectivity it is necessary to develop novel tools to study the global heteroreceptor networks. To provide insight into the overall topology of the GPCR heteromers and identify key players, a collective interaction network was constructed. Experimental interaction data for each of the individual human GPCR protomers was obtained manually from the STRING and SCOPUS databases. The interaction data were used to build and analyze the network using Cytoscape software. The network was treated as undirected throughout the study. It is comprised of 156 nodes, 260 edges and has a scale-free topology. Connectivity analysis reveals a significant dominance of intrafamily versus interfamily connections. Most of the receptors within the network are linked to each other by a small number of edges. DRD2, OPRM, ADRB2, AA2AR, AA1R, OPRK, OPRD and GHSR are identified as hubs. In a network representation 10 modules/clusters also appear as a highly interconnected group of nodes. Information on this GPCR network can improve our understanding of molecular integration. GPCR-HetNet has been implemented in Java and is freely available at http://www.iiia.csic.es/~ismel/GPCR-Nets/index.html

The G protein-coupled receptor heterodimer network (GPCR-HetNet) and its hub components

G protein-coupled receptors (GPCRs) oligomerization has emerged as a vital characteristic of receptor structure. Substantial experimental evidence supports the existence of GPCR-GPCR interactions in a coordinated and cooperative manner. However, despite the current development of experimental techniques for large-scale detection of GPCR heteromers, in order to understand their connectivity it is necessary to develop novel tools to study the global heteroreceptor networks. To provide insight into the overall topology of the GPCR heteromers and identify key players, a collective interaction network was constructed. Experimental interaction data for each of the individual human GPCR protomers was obtained manually from the STRING and SCOPUS databases. The interaction data were used to build and analyze the network using Cytoscape software. The network was treated as undirected throughout the study. It is comprised of 156 nodes, 260 edges and has a scale-free topology. Connectivity analysis reveals a significant dominance of intrafamily versus interfamily connections. Most of the receptors within the network are linked to each other by a small number of edges. DRD2, OPRM, ADRB2, AA2AR, AA1R, OPRK, OPRD and GHSR are identified as hubs. In a network representation 10 modules/clusters also appear as a highly interconnected group of nodes. Information on this GPCR network can improve our understanding of molecular integration. GPCR-HetNet has been implemented in Java and is freely available at http://www.iiia.csic.es/~ismel/GPCR-Nets/index.html. © 2014 by the authors; licensee MDPI, Basel, Switzerland

Searching the GPCR heterodimer network (GPCR-hetnet) database for information to deduce the receptor–receptor interface and its role in the integration of receptor heterodimer functions

The G protein-coupled receptor heterocomplex network database (GPCR-hetnet) is a database designed to store information on GPCR heteroreceptor complexes and their allosteric receptor–receptor interactions. It is an expert-authored and peer-reviewed, curated collection of well-documented GPCR–GPCR interactions that span the gamut from classical GPCR–GPCR interactions to more complex receptor–receptor interactions (GPCR-Receptor Tyrosine Kinase and GPCR-ionotropic receptor/ligand gated ion channel). Although GPCR-hetnet contains interactions among GPCR from several different species, the curators have initially focused on receptor–receptor interactions in humans. Currently (August 2017) GPCR-hetnet contains information on 250 receptors (192 GPCR, 52 RTK, and 6 ionotropic receptors) and >1023 interactions. The GPCR-hetnet provides four searchable datasets: the hetnet, the non-hetnet, the rtknet, and the ionnet. Other supporting datasets include information about receptors that are present in GPCR-hetnet such as literature citations. This chapter describes in a basic protocol how to use, navigate, and browse through the GPCR-hetnet database to identify the clusters in which a receptor protomer of interest is involved, while further applicability are also described and introduced

Searching the GPCR Heterodimer Network (GPCR-hetnet) Database for Information to Deduce the Receptor–Receptor Interface and Its Role in the Integrationof Receptor Heterodimer Functions

The G protein-coupled receptor heterocomplex network database (GPCR-hetnet) is a database designed to store information on GPCR heteroreceptor complexes and their allosteric receptor–receptor interactions. It is an expert-authored and peer-reviewed, curated collection of well-documented GPCR–GPCR interactions that span the gamut from classical GPCR–GPCR interactions to more complex receptor– receptor interactions (GPCR-Receptor Tyrosine Kinase and GPCR-ionotropic receptor/ligand gated ion channel). Although GPCR-hetnet contains interactions among GPCR from several different species, the curators have initially focused on receptor–receptor interactions in humans. Currently (August 2017) GPCR-hetnet contains information on 250 receptors (192 GPCR, 52 RTK, and 6 ionotropic receptors) and >1023 interactions. The GPCR-hetnet provides four searchable datasets: the hetnet, the non-hetnet, the rtknet, and the ionnet. Other supporting datasets include information about receptors that are present in GPCR-hetnet such as literature citations. This chapter describes in a basic protocol how to use, navigate, and browse through the GPCR-hetnet database to identify the clusters in which a receptor protomer of interest is involved, while further applicability are also described and introduced