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Atsoniou K, Giannopoulou E, Georganta EM, Skoulakis EMC. Drosophila Contributions towards Understanding Neurofibromatosis 1. Cells 2024; 13:721. [PMID: 38667335 PMCID: PMC11048932 DOI: 10.3390/cells13080721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 04/28/2024] Open
Abstract
Neurofibromatosis 1 (NF1) is a multisymptomatic disorder with highly variable presentations, which include short stature, susceptibility to formation of the characteristic benign tumors known as neurofibromas, intense freckling and skin discoloration, and cognitive deficits, which characterize most children with the condition. Attention deficits and Autism Spectrum manifestations augment the compromised learning presented by most patients, leading to behavioral problems and school failure, while fragmented sleep contributes to chronic fatigue and poor quality of life. Neurofibromin (Nf1) is present ubiquitously during human development and postnatally in most neuronal, oligodendrocyte, and Schwann cells. Evidence largely from animal models including Drosophila suggests that the symptomatic variability may reflect distinct cell-type-specific functions of the protein, which emerge upon its loss, or mutations affecting the different functional domains of the protein. This review summarizes the contributions of Drosophila in modeling multiple NF1 manifestations, addressing hypotheses regarding the cell-type-specific functions of the protein and exploring the molecular pathways affected upon loss of the highly conserved fly homolog dNf1. Collectively, work in this model not only has efficiently and expediently modelled multiple aspects of the condition and increased understanding of its behavioral manifestations, but also has led to pharmaceutical strategies towards their amelioration.
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Affiliation(s)
- Kalliopi Atsoniou
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center “Alexander Fleming”, 16672 Athens, Greece; (K.A.); (E.G.)
- Laboratory of Experimental Physiology, Medical School, National and Kapodistrian University of Athens, 11527 Athens, Greece
| | - Eleni Giannopoulou
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center “Alexander Fleming”, 16672 Athens, Greece; (K.A.); (E.G.)
| | - Eirini-Maria Georganta
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center “Alexander Fleming”, 16672 Athens, Greece; (K.A.); (E.G.)
| | - Efthimios M. C. Skoulakis
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center “Alexander Fleming”, 16672 Athens, Greece; (K.A.); (E.G.)
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Foka K, Georganta EM, Semelidou O, Skoulakis EMC. Loss of the Schizophrenia-Linked Furin Protein from Drosophila Mushroom Body Neurons Results in Antipsychotic-Reversible Habituation Deficits. J Neurosci 2022; 42:7496-7511. [PMID: 36028314 PMCID: PMC9525163 DOI: 10.1523/jneurosci.1055-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 07/28/2022] [Accepted: 08/07/2022] [Indexed: 11/21/2022] Open
Abstract
Habituation is a conserved adaptive process essential for incoming information assessment, which drives the behavioral response decrement to recurrent inconsequential stimuli and does not involve sensory adaptation or fatigue. Although the molecular mechanisms underlying the process are not well understood, habituation has been reported to be defective in a number of disorders including schizophrenia. We demonstrate that loss of furin1, the Drosophila homolog of a gene whose transcriptional downregulation has been linked to schizophrenia, results in defective habituation to recurrent footshocks in mixed sex populations. The deficit is reversible by transgenic expression of the Drosophila or human Furin in adult α'/β' mushroom body neurons and by acute oral delivery of the typical antipsychotic haloperidol and the atypical clozapine, which are commonly used to treat schizophrenic patients. The results validate the proposed contribution of Furin downregulation in schizophrenia and suggest that defective footshock habituation is a Drosophila protophenotype of the human disorder.SIGNIFICANCE STATEMENT Genome-wide association studies have revealed a number of loci linked to schizophrenia, but most have not been verified experimentally in a relevant behavioral task. Habituation deficits constitute a schizophrenia endophenotype. Drosophila with attenuated expression of the schizophrenia-linked highly conserved Furin gene present delayed habituation reversible with acute exposure to antipsychotics. This strongly suggests that footshock habituation defects constitute a schizophrenia protophenotype in Drosophila Furthermore, determination of the neurons whose regulated activity is required for footshock habituation provides a facile metazoan system to expediently validate putative schizophrenia genes and variants in a well understood simple brain.
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Affiliation(s)
- Kyriaki Foka
- Institute for Fundamental Biomedical Research, Biomedical Science Research Centre "Alexander Fleming," 16672 Vari, Greece
- Department of Molecular Biology and Genetics, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Eirini-Maria Georganta
- Institute for Fundamental Biomedical Research, Biomedical Science Research Centre "Alexander Fleming," 16672 Vari, Greece
| | - Ourania Semelidou
- Institute for Fundamental Biomedical Research, Biomedical Science Research Centre "Alexander Fleming," 16672 Vari, Greece
| | - Efthimios M C Skoulakis
- Institute for Fundamental Biomedical Research, Biomedical Science Research Centre "Alexander Fleming," 16672 Vari, Greece
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Georganta EM, Moressis A, Skoulakis EMC. Associative Learning Requires Neurofibromin to Modulate GABAergic Inputs to Drosophila Mushroom Bodies. J Neurosci 2021; 41:5274-5286. [PMID: 33972401 PMCID: PMC8211548 DOI: 10.1523/jneurosci.1605-20.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 04/12/2021] [Accepted: 04/15/2021] [Indexed: 12/28/2022] Open
Abstract
Cognitive dysfunction is among the hallmark symptoms of Neurofibromatosis 1, and accordingly, loss of the Drosophila melanogaster ortholog of Neurofibromin 1 (dNf1) precipitates associative learning deficits. However, the affected circuitry in the adult CNS remained unclear and the compromised mechanisms debatable. Although the main evolutionarily conserved function attributed to Nf1 is to inactivate Ras, decreased cAMP signaling on its loss has been thought to underlie impaired learning. Using mixed sex populations, we determine that dNf1 loss results in excess GABAergic signaling to the central for associative learning mushroom body (MB) neurons, apparently suppressing learning. dNf1 is necessary and sufficient for learning within these non-MB neurons, as a dAlk and Ras1-dependent, but PKA-independent modulator of GABAergic neurotransmission. Surprisingly, we also uncovered and discuss a postsynaptic Ras1-dependent, but dNf1-independnet signaling within the MBs that apparently responds to presynaptic GABA levels and contributes to the learning deficit of the mutants.
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Affiliation(s)
- Eirini-Maria Georganta
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center "Alexander Fleming" Vari, 16672, Greece
| | - Anastasios Moressis
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center "Alexander Fleming" Vari, 16672, Greece
| | - Efthimios M C Skoulakis
- Institute for Fundamental Biomedical Research, Biomedical Sciences Research Center "Alexander Fleming" Vari, 16672, Greece
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Pallaki P, Georganta EM, Serafimidis I, Papakonstantinou MP, Papanikolaou V, Koutloglou S, Papadimitriou E, Agalou A, Tserga A, Simeonof A, Thomaidou D, Gaitanou M, Georgoussi Z. A novel regulatory role of RGS4 in STAT5B activation, neurite outgrowth and neuronal differentiation. Neuropharmacology 2017; 117:408-421. [PMID: 28219718 DOI: 10.1016/j.neuropharm.2017.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 02/01/2017] [Accepted: 02/14/2017] [Indexed: 12/26/2022]
Abstract
The Regulator of G protein Signalling 4 (RGS4) is a multitask protein that interacts with and negatively modulates opioid receptor signalling. Previously, we showed that the δ-opioid receptor (δ-OR) forms a multiprotein signalling complex consisting of Gi/Go proteins and the Signal Transducer and Activator of Transcription 5B (STAT5B) that leads to neuronal differentiation and neurite outgrowth upon δ-ΟR activation. Here, we investigated whether RGS4 could participate in signalling pathways to regulate neurotropic events. We demonstrate that RGS4 interacts directly with STAT5B independently of δ-ΟR presence both in vitro and in living cells. This interaction involves the N-terminal portion of RGS4 and the DNA-binding SH3 domain of STAT5B. Expression of RGS4 in HEK293 cells expressing δ-OR and/or erythropoietin receptor results in inhibition of [D-Ser2, Leu5, Thr6]-enkephalin (DSLET)-and erythropoietin-dependent STAT5B phosphorylation and subsequent transcriptional activation. DSLET-dependent neurite outgrowth of neuroblastoma cells is also blocked by RGS4 expression, whereas primary cortical cultures of RGS4 knockout mice (RGS4-/-) exhibit enhanced neuronal sprouting after δ-OR activation. Additional studies in adult brain extracts from RGS4-/- mice revealed increased levels of p-STAT5B. Finally, neuronal progenitor cultures from RGS4-/- mice exhibit enhanced proliferation with concomitant increases in the mRNA levels of the anti-apoptotic STAT5B target genes bcl2 and bcl-xl. These observations suggest that RGS4 is implicated in opioid dependent neuronal differentiation and neurite outgrowth via a "non-canonical" signaling pathway regulating STAT5B-directed responses.
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Affiliation(s)
- Paschalina Pallaki
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Eirini-Maria Georganta
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Ioannis Serafimidis
- Laboratory of Developmental Biology, Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece
| | - Maria-Pagona Papakonstantinou
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Vassilis Papanikolaou
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Sofia Koutloglou
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Elsa Papadimitriou
- Laboratory of Cellular and Molecular Neurobiology, Hellenic Pasteur Institute, 11521 Athens, Greece
| | - Adamantia Agalou
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Aggeliki Tserga
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Alexandra Simeonof
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece
| | - Dimitra Thomaidou
- Laboratory of Cellular and Molecular Neurobiology, Hellenic Pasteur Institute, 11521 Athens, Greece
| | - Maria Gaitanou
- Laboratory of Cellular and Molecular Neurobiology, Hellenic Pasteur Institute, 11521 Athens, Greece
| | - Zafiroula Georgoussi
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biosciences and Applications, National Centre for Scientific Research «Demokritos», 15310 Athens, Greece.
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Georganta EM, Tsoutsi L, Gaitanou M, Georgoussi Z. δ-opioid receptor activation leads to neurite outgrowth and neuronal differentiation via a STAT5B-Gαi/o pathway. J Neurochem 2013; 127:329-41. [DOI: 10.1111/jnc.12386] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 06/27/2013] [Accepted: 07/29/2013] [Indexed: 12/25/2022]
Affiliation(s)
- Eirini-Maria Georganta
- Laboratory of Cellular Signalling and Molecular Pharmacology; Institute of Biosciences and Applications; National Centre for Scientific Research “Demokritos”; Athens Greece
| | - Lambrini Tsoutsi
- Laboratory of Cellular Signalling and Molecular Pharmacology; Institute of Biosciences and Applications; National Centre for Scientific Research “Demokritos”; Athens Greece
| | - Maria Gaitanou
- Laboratory of Cellular and Molecular Neurobiology; Hellenic Pasteur Institute; Athens Greece
| | - Zafiroula Georgoussi
- Laboratory of Cellular Signalling and Molecular Pharmacology; Institute of Biosciences and Applications; National Centre for Scientific Research “Demokritos”; Athens Greece
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Georgoussi Z, Georganta EM, Milligan G. The other side of opioid receptor signalling: regulation by protein-protein interaction. Curr Drug Targets 2012; 13:80-102. [PMID: 21777181 DOI: 10.2174/138945012798868470] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 03/23/2011] [Accepted: 03/26/2011] [Indexed: 11/22/2022]
Abstract
Opiate drugs mediate their analgesic, euphoriant, and rewarding effects by activating opioid receptors. Pharmacological and molecular studies have demonstrated the existence of three opioid receptor subtypes, μ, δ, and κ- that couple predominantly to Gi/Go types of G proteins to regulate the activity of a diverse array of effector systems. Ample experimental evidence has demonstrated that these receptors can physically interact with a variety of accessory proteins, confirming that signal transduction of the opioid receptors is not restricted to heterotrimeric G protein activation. Such interactions can alter the effectiveness of agonist-driven cell signalling, determine the signals generated and alter the trafficking, targeting, fine tuning and cellular localization of these receptors by providing a scaffold that links the receptors to the cytoskeletal network. The current review will summarize opioid receptor interacting partners and their role as currently understood. Increasing knowledge of the mechanisms by which these interactions are regulated is expected to address problems related to phenomena such as pain perception, tolerance and dependence that occur upon chronic opiate administration and define whether disruption of such interactions may contribute to the development of novel therapeutic strategies.
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Affiliation(s)
- Zafiroula Georgoussi
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research "Demokritos", Aghia Paraskevi 15310, Athens, Greece.
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Georganta EM, Georgoussi Z. δ-opioid receptor activation leads to neurite outgrowth and neuronal survival via a STAT5B-Gαi/o pathway. Pharmacol Rep 2011. [DOI: 10.1016/s1734-1140(11)70458-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Georganta EM, Agalou A, Georgoussi Z. Multi-component signaling complexes of the delta-opioid receptor with STAT5B and G proteins. Neuropharmacology 2010; 59:139-48. [PMID: 20433855 DOI: 10.1016/j.neuropharm.2010.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 02/25/2010] [Accepted: 04/09/2010] [Indexed: 11/28/2022]
Abstract
Besides mediating opioid responses in the nervous system and the peripheral tissues, opioid receptors are implicated in signaling mechanisms shared by cytokine receptors. Recent observations have shown that the Signal Transducer and Activator of Transcription 5A (STAT5A) interacts with the mu-opioid receptor (mu-OR) and is phosphorylated upon mu-OR stimulation (Mazarakou and Georgoussi, 2005). In the present study we demonstrate that another member of the STAT family, STAT5B, associates constitutively with the C-terminal tail of the delta-opioid receptor (delta-CT). [D-Ser(2), Leu(5), Thr(6)]-enkephalin-exposure of HEK293 cells, expressing stably the delta-opioid receptor (delta-OR), leads to receptor-dependent STAT5B tyrosine phosphorylation and transcriptional activation. This phosphorylation occurs in a G protein-dependent manner and is carried out by a c-Src kinase. Co-immunoprecipitation studies indicate that STAT5B forms pairs with selective Galpha and Gbetagamma subunits of G proteins and activated c-Src kinase in HEK293 cells. These interactions are formed either constitutively, or upon receptor stimulation. We also demonstrate that the delta-CT serves as a platform for the formation of a multi-component signaling complex (signalosome), consisting of STAT5B, c-Src and selective G protein members. We can thus conclude that STAT5B signaling can be modulated by its coupling with a specific subset of G protein subunits, revealing a novel signaling mechanism for the transcriptional regulation of STAT5B-dependent genes.
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Affiliation(s)
- Eirini-Maria Georganta
- Laboratory of Cellular Signaling and Molecular Pharmacology, Institute of Biology, National Centre for Scientific Research Demokritos, 15310 Ag. Paraskevi-Attikis, Athens, Greece
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