Neurotransmitter Receptor Homologues of Dictyostelium discoideum

Fountain, Samuel J.

doi:10.1007/s12031-009-9298-0

Cited by 9 publications

(8 citation statements)

References 15 publications

(22 reference statements)

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“…Functionally, DdmGluPR is involved in early development of D. discoideum [37]. GABA produced by D. discoideum also functions as an intracellular signaling molecule by regulating differentiation during development through a GABA B receptor homologue [38,39]. D. discoideum thus provides an example whereby class C receptors play an important functional role in the absence of neuronal synapses, and may therefore shed light on the functionality of potential diatom GPCRs.…”

Section: Discussionmentioning

confidence: 99%

Identification of G protein-coupled receptor signaling pathway proteins in marine diatoms using comparative genomics

et al. 2013

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BackgroundThe G protein-coupled receptor (GPCR) signaling pathway plays an essential role in signal transmission and response to external stimuli in mammalian cells. Protein components of this pathway have been characterized in plants and simpler eukaryotes such as yeast, but their presence and role in unicellular photosynthetic eukaryotes have not been determined. We use a comparative genomics approach using whole genome sequences and gene expression libraries of four diatoms (Pseudo-nitzschia multiseries, Thalassiosira pseudonana, Phaeodactylum tricornutum and Fragilariopsis cylindrus) to search for evidence of GPCR signaling pathway proteins that share sequence conservation to known GPCR pathway proteins.ResultsThe majority of the core components of GPCR signaling were well conserved in all four diatoms, with protein sequence similarity to GPCRs, human G protein α- and β-subunits and downstream effectors. There was evidence for the Gγ-subunit and thus a full heterotrimeric G protein only in T. pseudonana. Phylogenetic analysis of putative diatom GPCRs indicated similarity but deep divergence to the class C GPCRs, with branches basal to the GABAB receptor subfamily. The extracellular and intracellular regions of these putative diatom GPCR sequences exhibited large variation in sequence length, and seven of these sequences contained the necessary ligand binding domain for class C GPCR activation. Transcriptional data indicated that a number of the putative GPCR sequences are expressed in diatoms under various stress conditions in culture, and that many of the GPCR-activated signaling proteins, including the G protein, are also expressed.ConclusionsThe presence of sequences in all four diatoms that code for the proteins required for a functional mammalian GPCR pathway highlights the highly conserved nature of this pathway and suggests a complex signaling machinery related to environmental perception and response in these unicellular organisms. The lack of evidence for some GPCR pathway proteins in one or more of the diatoms, such as the Gγ-subunit, may be due to differences in genome completeness and genome coverage for the four diatoms. The high divergence of putative diatom GPCR sequences to known class C GPCRs suggests these sequences may represent another, potentially ancestral, subfamily of class C GPCRs.

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Section: Discussionmentioning

confidence: 99%

Identification of G protein-coupled receptor signaling pathway proteins in marine diatoms using comparative genomics

et al. 2013

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Section: Introductionmentioning

confidence: 99%

“…In the social amoeba Dictysotelium, disruption of a glutamate receptor by homologous recombination reveals a role for glutamate signaling in the suppression of cell division (Taniura et al, 2006), while GABA induces terminal differentiation of spores through a GABA B receptor (Anjard and Loomis, 2006). GABA and glutamate appear to play opposing roles in spore induction (Fountain, 2010) in Dictyostelium, indicating that the apparent antagonistic relationship between glutamate and GABA signaling was established prior to the evolution of synaptic communication in the CNS.Furthermore, neurotransmitters control cell proliferation during development long before the onset of neurogenesis in mammals, as exemplified by GABA signaling in the early embryo (Andäng et al, 2008). Once developmental neurogenesis is initiated, neurotransmitter signaling has an impact on several aspects of neurogenesis, including proliferation, migration and differentiation in various locations in the CNS, such as the telencephalon, ventral midbrain and retina (Kim et al, 2006;Schlett, 2006;Heng et al, 2007;Martins and Pearson, 2008).…”

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Neurotransmitter-mediated control of neurogenesis in the adult vertebrate brain

et al. 2013

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SummaryIt was long thought that no new neurons are added to the adult brain. Similarly, neurotransmitter signaling was primarily associated with communication between differentiated neurons. Both of these ideas have been challenged, and a crosstalk between neurogenesis and neurotransmitter signaling is beginning to emerge. In this Review, we discuss neurotransmitter signaling as it functions at the intersection of stem cell research and regenerative medicine, exploring how it may regulate the formation of new functional neurons and outlining interactions with other signaling pathways. We consider evolutionary and cross-species comparative aspects, and integrate available results in the context of normal physiological versus pathological conditions. We also discuss the potential role of neurotransmitters in brain size regulation and implications for cell replacement therapies. Key words: Adult neurogenesis, Homeostasis, Neural stem cell, Neurotransmitter, Regeneration IntroductionIn the brain, signaling via neurotransmitters, small molecules released by neurons to communicate with other cells, has primarily been associated with the function rather than with the formation of neurons. However, several reports have identified roles for neurotransmitters in cell fate determination in a wide range of species both within and outside the central nervous system (CNS). A thorough discussion on the evolutionary origin of neurotransmitter signaling is outside the scope of this Review, but it is important to note that both neurotransmitters and their receptors (see Table 1) are present and functionally important in organisms without a nervous system. For example, γ-aminobutyric acid (GABA), glutamate and nitric oxide (NO) have all been detected in sponges and shown to regulate cell behavior (Ellwanger et al., 2007;Elliott and Leys, 2010). A recent transcriptome profiling of the sponge A. queenslandica revealed the expression of wide repertoire of components active in synapses found in the vertebrate nervous systems (Conaco et al., 2012). In the social amoeba Dictysotelium, disruption of a glutamate receptor by homologous recombination reveals a role for glutamate signaling in the suppression of cell division (Taniura et al., 2006), while GABA induces terminal differentiation of spores through a GABA B receptor (Anjard and Loomis, 2006). GABA and glutamate appear to play opposing roles in spore induction (Fountain, 2010) in Dictyostelium, indicating that the apparent antagonistic relationship between glutamate and GABA signaling was established prior to the evolution of synaptic communication in the CNS.Furthermore, neurotransmitters control cell proliferation during development long before the onset of neurogenesis in mammals, as exemplified by GABA signaling in the early embryo (Andäng et al., 2008). Once developmental neurogenesis is initiated, neurotransmitter signaling has an impact on several aspects of neurogenesis, including proliferation, migration and differentiation in various locations in the CNS, such as the tele...

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“…Given the known impacts of RDX exposure on nervous system processes, investigation of the molecular functions affected by RDX exposure, including GABAergic signaling (Williams et al 2011), constitute a key focus for understanding the impacts of RDX across disparate phylogenetic lineages. GABA receptors have been described in many different phyla such as social amoeba (Dictyostelium discodeum), cnidarians, mollusks, annelids, arthropods, nematodes, and chordates (Kass- Simon and Pierobon 2007;Tsang et al 2007; Kehoe et al 2009;Fountain 2010). The GABA A R is an ionotropic receptor and ligand-gated ion channel.…”

Section: Introductionmentioning

confidence: 99%

Conserved toxic responses across divergent phylogenetic lineages: a meta-analysis of the neurotoxic effects of RDX among multiple species using toxicogenomics

García-Reyero

Habib²,

Pirooznia

et al. 2011

Ecotoxicology

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At military training sites, a variety of pollutants such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), may contaminate the area originating from used munitions. Studies investigating the mechanism of toxicity of RDX have shown that it affects the central nervous system causing seizures in humans and animals. Environmental pollutants such as RDX have the potential to affect many different species, therefore it is important to establish how phylogenetically distant species may respond to these types of emerging pollutants. In this paper, we have used a transcriptional network approach to compare and contrast the neurotoxic effects of RDX among five phylogenetically disparate species: rat (Sprague-Dawley), Northern bobwhite quail (Colinus virginianus), fathead minnow (Pimephales promelas), earthworm (Eisenia fetida), and coral (Acropora formosa). Pathway enrichment analysis indicated a conservation of RDX impacts on pathways related to neuronal function in rat, Northern bobwhite quail, fathead minnows and earthworm, but not in coral. As evolutionary distance increased common responses decreased with impacts on energy and metabolism dominating effects in coral. A neurotransmission related transcriptional network based on whole rat brain responses to RDX exposure was used to identify functionally related modules of genes, components of which were conserved across species depending upon evolutionary distance. Overall, the meta-analysis using genomic data of the effects of RDX on several species suggested a common and conserved mode of action of the chemical throughout phylogenetically remote organisms.

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Neurotransmitter Receptor Homologues of Dictyostelium discoideum

Cited by 9 publications

References 15 publications

Identification of G protein-coupled receptor signaling pathway proteins in marine diatoms using comparative genomics

Identification of G protein-coupled receptor signaling pathway proteins in marine diatoms using comparative genomics

Neurotransmitter-mediated control of neurogenesis in the adult vertebrate brain

Conserved toxic responses across divergent phylogenetic lineages: a meta-analysis of the neurotoxic effects of RDX among multiple species using toxicogenomics

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