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Powis G, Meuillet EJ, Indarte M, Booher G, Kirkpatrick L. Pleckstrin Homology [PH] domain, structure, mechanism, and contribution to human disease. Biomed Pharmacother 2023; 165:115024. [PMID: 37399719 DOI: 10.1016/j.biopha.2023.115024] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 06/14/2023] [Indexed: 07/05/2023] Open
Abstract
The pleckstrin homology [PH] domain is a structural fold found in more than 250 proteins making it the 11th most common domain in the human proteome. 25% of family members have more than one PH domain and some PH domains are split by one, or several other, protein domains although still folding to give functioning PH domains. We review mechanisms of PH domain activity, the role PH domain mutation plays in human disease including cancer, hyperproliferation, neurodegeneration, inflammation, and infection, and discuss pharmacotherapeutic approaches to regulate PH domain activity for the treatment of human disease. Almost half PH domain family members bind phosphatidylinositols [PIs] that attach the host protein to cell membranes where they interact with other membrane proteins to give signaling complexes or cytoskeleton scaffold platforms. A PH domain in its native state may fold over other protein domains thereby preventing substrate access to a catalytic site or binding with other proteins. The resulting autoinhibition can be released by PI binding to the PH domain, or by protein phosphorylation thus providing fine tuning of the cellular control of PH domain protein activity. For many years the PH domain was thought to be undruggable until high-resolution structures of human PH domains allowed structure-based design of novel inhibitors that selectively bind the PH domain. Allosteric inhibitors of the Akt1 PH domain have already been tested in cancer patients and for proteus syndrome, with several other PH domain inhibitors in preclinical development for treatment of other human diseases.
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Affiliation(s)
- Garth Powis
- PHusis Therapeutics Inc., 6019 Folsom Drive, La Jolla, CA 92037, USA.
| | | | - Martin Indarte
- PHusis Therapeutics Inc., 6019 Folsom Drive, La Jolla, CA 92037, USA
| | - Garrett Booher
- PHusis Therapeutics Inc., 6019 Folsom Drive, La Jolla, CA 92037, USA
| | - Lynn Kirkpatrick
- PHusis Therapeutics Inc., 6019 Folsom Drive, La Jolla, CA 92037, USA
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2
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Hines DJ, Contreras A, Garcia B, Barker JS, Boren AJ, Moufawad El Achkar C, Moss SJ, Hines RM. Human ARHGEF9 intellectual disability syndrome is phenocopied by a mutation that disrupts collybistin binding to the GABA A receptor α2 subunit. Mol Psychiatry 2022; 27:1729-1741. [PMID: 35169261 PMCID: PMC9095487 DOI: 10.1038/s41380-022-01468-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 01/12/2022] [Accepted: 01/26/2022] [Indexed: 11/20/2022]
Abstract
Intellectual disability (ID) is a common neurodevelopmental disorder that can arise from genetic mutations ranging from trisomy to single nucleotide polymorphism. Mutations in a growing number of single genes have been identified as causative in ID, including ARHGEF9. Evaluation of 41 ARHGEF9 patient reports shows ubiquitous inclusion of ID, along with other frequently reported symptoms of epilepsy, abnormal baseline EEG activity, behavioral symptoms, and sleep disturbances. ARHGEF9 codes for the Cdc42 Guanine Nucleotide Exchange Factor 9 collybistin (Cb), a known regulator of inhibitory synapse function via direct interaction with the adhesion molecule neuroligin-2 and the α2 subunit of GABAA receptors. We mutate the Cb binding motif within the large intracellular loop of α2 replacing it with the binding motif for gephyrin from the α1 subunit (Gabra2-1). The Gabra2-1 mutation causes a strong downregulation of Cb expression, particularly at cholecystokinin basket cell inhibitory synapses. Gabra2-1 mice have deficits in working and recognition memory, as well as hyperactivity, anxiety, and reduced social preference, recapitulating the frequently reported features of ARHGEF9 patients. Gabra2-1 mice also have spontaneous seizures during postnatal development which can lead to mortality, and baseline abnormalities in low-frequency wavelengths of the EEG. EEG abnormalities are vigilance state-specific and manifest as sleep disturbance including increased time in wake and a loss of free-running rhythmicity in the absence of light as zeitgeber. Gabra2-1 mice phenocopy multiple features of human ARHGEF9 mutation, and reveal α2 subunit-containing GABAA receptors as a druggable target for treatment of this complex ID syndrome.
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Affiliation(s)
- Dustin J Hines
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - April Contreras
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Betsua Garcia
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Jeffrey S Barker
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Austin J Boren
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA
| | | | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Rochelle M Hines
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV, USA.
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3
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Selective Overexpression of Collybistin in Mouse Hippocampal Pyramidal Cells Enhances GABAergic Neurotransmission and Protects against PTZ-Induced Seizures. eNeuro 2021; 8:ENEURO.0561-20.2021. [PMID: 34083383 PMCID: PMC8281261 DOI: 10.1523/eneuro.0561-20.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 04/02/2021] [Accepted: 05/23/2021] [Indexed: 11/21/2022] Open
Abstract
Collybistin (CB) is a rho guanine exchange factor found at GABAergic and glycinergic postsynapses that interacts with the inhibitory scaffold protein, gephyrin, and induces accumulation of gephyrin and GABA type-A receptors (GABAARs) to the postsynapse. We have previously reported that the isoform without the src homology 3 (SH3) domain, CBSH3-, is particularly active in enhancing the GABAergic postsynapse in both cultured hippocampal neurons as well as in cortical pyramidal neurons after chronic in vivo expression in in utero electroporated (IUE) rats. Deficiency of CB in knock-out (KO) mice results in absence of gephyrin and gephyrin-dependent GABAARs at postsynaptic sites in several brain regions, including hippocampus. In the present study, we have generated an adeno-associated virus (AAV) that expresses CBSH3- in a cre-dependent manner. Using male and female VGLUT1-IRES-cre or VGAT-IRES-cre mice, we explore the effect of overexpression of CBSH3- in hippocampal pyramidal cells or hippocampal interneurons. The results show that: (1) the accumulation of gephyrin and GABAARs at inhibitory postsynapses in hippocampal pyramidal neurons or interneurons can be enhanced by CBSH3- overexpression; (2) overexpression of CBSH3- in hippocampal pyramidal cells can enhance the strength of inhibitory neurotransmission; and (3) these enhanced inhibitory synapses provide protection against pentylenetetrazole (PTZ)-induced seizures. The results indicate that this AAV vector carrying CBSH3- can be used for in vivo enhancement of GABAergic synaptic transmission in selected target neurons in the brain.
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4
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Wagner S, Lee C, Rojas L, Specht CG, Rhee J, Brose N, Papadopoulos T. The α3 subunit of GABA A receptors promotes formation of inhibitory synapses in the absence of collybistin. J Biol Chem 2021; 296:100709. [PMID: 33901490 PMCID: PMC8141935 DOI: 10.1016/j.jbc.2021.100709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 04/14/2021] [Accepted: 04/22/2021] [Indexed: 01/03/2023] Open
Abstract
Signaling at nerve cell synapses is a key determinant of proper brain function, and synaptic defects—or synaptopathies—are at the basis of many neurological and psychiatric disorders. Collybistin (CB), a brain-specific guanine nucleotide exchange factor, is essential for the formation of γ-aminobutyric acidergic (GABAergic) postsynapses in defined regions of the mammalian forebrain, including the hippocampus and basolateral amygdala. This process depends on a direct interaction of CB with the scaffolding protein gephyrin, which leads to the redistribution of gephyrin into submembranous clusters at nascent inhibitory synapses. Strikingly, synaptic clustering of gephyrin and GABAA type A receptors (GABAARs) in several brain regions, including the cerebral cortex and certain thalamic areas, is unperturbed in CB-deficient mice, indicating that the formation of a substantial subset of inhibitory postsynapses must be controlled by gephyrin-interacting proteins other than CB. Previous studies indicated that the α3 subunit of GABAARs (GABAAR-α3) binds directly and with high affinity to gephyrin. Here, we provide evidence (i) that a homooligomeric GABAAR-α3A343W mutant induces the formation of submembranous gephyrin clusters independently of CB in COS-7 cells, (ii) that gephyrin clustering is unaltered in the neuronal subpopulations endogenously expressing the GABAAR-α3 in CB-deficient brains, and (iii) that exogenous expression of GABAAR-α3 partially rescues impaired gephyrin clustering in CB-deficient hippocampal neurons. Our results identify an important role of GABAAR-α3 in promoting gephyrin-mediated and CB-independent formation of inhibitory postsynapses.
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Affiliation(s)
- Sven Wagner
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - ChoongKu Lee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Lucia Rojas
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Christian G Specht
- Diseases and Hormones of the Nervous System (DHNS), Inserm U1195, Université Paris-Saclay, Le Kremlin-Bicêtre, France
| | - JeongSeop Rhee
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
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5
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Ghesh L, Besnard T, Nizon M, Trochu E, Landeau-Trottier G, Breheret F, Thauvin-Robinet C, Bruel AL, Kuentz P, Coubes C, Cuisset L, Mignot C, Keren B, Bézieau S, Cogné B. Loss-of-function variants in ARHGEF9 are associated with an X-linked intellectual disability dominant disorder. Hum Mutat 2021; 42:498-505. [PMID: 33600053 DOI: 10.1002/humu.24188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 01/28/2021] [Accepted: 02/14/2021] [Indexed: 01/12/2023]
Abstract
ARHGEF9 defects lead to an X-linked intellectual disability disorder related to inhibitory synaptic dysfunction. This condition is more frequent in males, with a few affected females reported. Up to now, sequence variants and gross deletions have been identified in males, while only chromosomal aberrations have been reported in affected females who showed a skewed pattern of X-chromosome inactivation (XCI), suggesting an X-linked recessive (XLR) disorder. We report three novel loss-of-function (LoF) variants in ARHGEF9: A de novo synonymous variant affecting splicing (NM_015185.2: c.1056G>A, p.(Lys352=)) in one female; a nonsense variant in another female (c.865C>T, p.(Arg289*)), that is, also present as a somatically mosaic variant in her father, and a de novo nonsense variant in a boy (c.899G>A; p.(Trp300*)). Both females showed a random XCI. Thus, we suggest that missense variants are responsible for an XLR disorder affecting males and that LoF variants, mainly occurring de novo, may be responsible for an X-linked dominant disorder affecting males and females.
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Affiliation(s)
- Leïla Ghesh
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Thomas Besnard
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
- l'institut du thorax, Université de Nantes, CNRS, INSERM, Nantes, France
| | - Mathilde Nizon
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
- l'institut du thorax, Université de Nantes, CNRS, INSERM, Nantes, France
| | - Eva Trochu
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | | | - Flora Breheret
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Christel Thauvin-Robinet
- FHU TRANSLAD, Centre Hospitalier Universitaire Dijon-Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
- Génétique des Anomalies du Développement, Inserm UMR 1231, Université de Bourgogne, Dijon, France
- Centre de Génétique et Centre de Référence Déficience Intellectuelle de causes rares, Hôpital d'Enfants, Centre Hospitalier Universitaire Dijon-Bourgogne, Dijon, France
- UF Innovation en diagnostic génomique des maladies rares, CHU Dijon, Dijon, France
| | - Ange-Line Bruel
- FHU TRANSLAD, Centre Hospitalier Universitaire Dijon-Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
- Génétique des Anomalies du Développement, Inserm UMR 1231, Université de Bourgogne, Dijon, France
- UF Innovation en diagnostic génomique des maladies rares, CHU Dijon, Dijon, France
| | - Paul Kuentz
- FHU TRANSLAD, Centre Hospitalier Universitaire Dijon-Bourgogne et Université de Bourgogne-Franche Comté, Dijon, France
- Génétique des Anomalies du Développement, Inserm UMR 1231, Université de Bourgogne, Dijon, France
| | - Christine Coubes
- Département de Génétique Médicale, Maladies Rares et Médecine Personnalisée, Hôpital Arnaud de Villeneuve, CHU de Montpellier, Montpellier, France
| | - Laurence Cuisset
- Laboratoire de Génétique et Biologie Moléculaires, Département Médico-Universitaire BioPhyGen, Hôpital Cochin, APHP, Université de Paris, Paris, France
| | - Cyril Mignot
- Institut du Cerveau et de la Moelle épinière, ICM, INSERM, U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Paris, France
- Service de Génétique clinique et Médicale, CHU Paris, Hôpital Pitié-Salpêtrière, Paris, France
| | - Boris Keren
- Service de Génétique clinique et Médicale, CHU Paris, Hôpital Pitié-Salpêtrière, Paris, France
| | - Stéphane Bézieau
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
- l'institut du thorax, Université de Nantes, CNRS, INSERM, Nantes, France
| | - Benjamin Cogné
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nantes, Nantes, France
- l'institut du thorax, Université de Nantes, CNRS, INSERM, Nantes, France
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6
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George S, Bear J, Taylor MJ, Kanamalla K, Fekete CD, Chiou TT, Miralles CP, Papadopoulos T, De Blas AL. Collybistin SH3-protein isoforms are expressed in the rat brain promoting gephyrin and GABA-A receptor clustering at GABAergic synapses. J Neurochem 2021; 157:1032-1051. [PMID: 33316079 DOI: 10.1111/jnc.15270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/18/2020] [Accepted: 12/08/2020] [Indexed: 01/21/2023]
Abstract
Collybistin (CB) is a guanine nucleotide exchange factor (GEF) selectively localized at GABAergic and glycinergic postsynapses. Analysis of mRNA shows that several isoforms of collybistin are expressed in the brain. Some of the isoforms have a SH3 domain (CBSH3+) and some have no SH3 domain (CBSH3-). The CBSH3+ mRNAs are predominantly expressed over CBSH3-. However, in an immunoblot study of mouse brain homogenates, only CBSH3+ protein isoforms were detected, proposing that CBSH3- protein might not be expressed in the brain. The expression or lack of expression of CBSH3- protein is an important issue because CBSH3- has a strong effect in promoting the postsynaptic clustering of gephyrin and GABA-A receptors (GABAA Rs). Moreover CBSH3- is constitutively active; therefore lower expression of CBSH3- protein might play a relatively stronger functional role than the more abundant but self-inhibited CBSH3+ isoforms, which need to be activated. We are now showing that: (a) CBSH3- protein is expressed in the brain; (b) parvalbumin positive (PV+) interneurons show higher expression of CBSH3- protein than other neurons; (c) CBSH3- is associated with GABAergic synapses in various regions of the brain and (d) knocking down CBSH3- in hippocampal neurons decreases the synaptic clustering of gephyrin and GABAA Rs. The results show that CBSH3- protein is expressed in the brain and that it plays a significant role in the size regulation of the GABAergic postsynapse.
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Affiliation(s)
- Shanu George
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - John Bear
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Michael J Taylor
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Karthik Kanamalla
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Christopher D Fekete
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Tzu-Ting Chiou
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Celia P Miralles
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | | | - Angel L De Blas
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
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7
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Schäfer J, Förster L, Mey I, Papadopoulos T, Brose N, Steinem C. Neuroligin-2 dependent conformational activation of collybistin reconstituted in supported hybrid membranes. J Biol Chem 2020; 295:18604-18613. [PMID: 33127642 PMCID: PMC7939476 DOI: 10.1074/jbc.ra120.015347] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/27/2020] [Indexed: 12/23/2022] Open
Abstract
The assembly of the postsynaptic transmitter sensing machinery at inhibitory nerve cell synapses requires the intimate interplay between cell adhesion proteins, scaffold and adaptor proteins, and γ-aminobutyric acid (GABA) or glycine receptors. We developed an in vitro membrane system to reconstitute this process, to identify the essential protein components, and to define their mechanism of action, with a specific focus on the mechanism by which the cytosolic C terminus of the synaptic cell adhesion protein Neuroligin-2 alters the conformation of the adaptor protein Collybistin-2 and thereby controls Collybistin-2-interactions with phosphoinositides (PtdInsPs) in the plasma membrane. Supported hybrid membranes doped with different PtdInsPs and 1,2-dioleoyl-sn-glycero-3-{[N-(5-amino-1-carboxypentyl)iminodiacetic acid]succinyl} nickel salt (DGS-NTA(Ni)) to allow for the specific adsorption of the His6-tagged intracellular domain of Neuroligin-2 (His-cytNL2) were prepared on hydrophobically functionalized silicon dioxide substrates via vesicle spreading. Two different collybistin variants, the WT protein (CB2SH3) and a mutant that adopts an intrinsically 'open' and activated conformation (CB2SH3/W24A-E262A), were bound to supported membranes in the absence or presence of His-cytNL2. The corresponding binding data, obtained by reflectometric interference spectroscopy, show that the interaction of the C terminus of Neuroligin-2 with Collybistin-2 induces a conformational change in Collybistin-2 that promotes its interaction with distinct membrane PtdInsPs.
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Affiliation(s)
- Jonas Schäfer
- Institute for Organic and Biomolecular Chemistry, Georg August University, Göttingen, Germany
| | - Lucas Förster
- Institute for Organic and Biomolecular Chemistry, Georg August University, Göttingen, Germany
| | - Ingo Mey
- Institute for Organic and Biomolecular Chemistry, Georg August University, Göttingen, Germany
| | | | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany.
| | - Claudia Steinem
- Institute for Organic and Biomolecular Chemistry, Georg August University, Göttingen, Germany; Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.
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Scala M, Zonneveld-Huijssoon E, Brienza M, Mecarelli O, van der Hout AH, Zambrelli E, Turner K, Zara F, Peron A, Vignoli A, Striano P. De novo ARHGEF9 missense variants associated with neurodevelopmental disorder in females: expanding the genotypic and phenotypic spectrum of ARHGEF9 disease in females. Neurogenetics 2020; 22:87-94. [PMID: 32939676 DOI: 10.1007/s10048-020-00622-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 07/21/2020] [Indexed: 11/24/2022]
Abstract
Individuals harboring pathogenic variants in ARHGEF9, encoding an essential submembrane protein for gamma-aminobutyric acid (GABA)-ergic synapses named collybistin, show intellectual disability (ID), facial dysmorphism, behavioral disorders, and epilepsy. Only few affected females carrying large chromosomal rearrangements involving ARHGEF9 have been reported so far. Through next-generation sequencing (NGS)-based panels, we identified two single nucleotide variants (SNVs) in ARHGEF9 in two females with neurodevelopmental features. Sanger sequencing revealed that these variants were de novo. The X-inactivation pattern in peripheral blood cells was random. We report the first affected females harboring de novo SNVs in ARHGEF9, expanding the genotypic and phenotypic spectrum of ARHGEF9-related neurodevelopmental disorder in females.
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Affiliation(s)
- Marcello Scala
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy. .,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.
| | - Evelien Zonneveld-Huijssoon
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marianna Brienza
- Department of Human Neurosciences, Policlinico Umberto I Hospital, Sapienza University, Rome, Italy
| | - Oriano Mecarelli
- Department of Human Neurosciences, Policlinico Umberto I Hospital, Sapienza University, Rome, Italy
| | - Annemarie H van der Hout
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Elena Zambrelli
- Epilepsy Center - Sleep Medicine Center, San Paolo Hospital, Milan, Italy
| | - Katherine Turner
- Epilepsy Center - Sleep Medicine Center, San Paolo Hospital, Milan, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.,Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Angela Peron
- Child Neuropsychiatry Unit - Epilepsy Center, San Paolo Hospital, Milan, Italy.,Department of Health Sciences, Università degli Studi di Milano, Milan, Italy.,Department of Pediatrics, Division of Medical Genetics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Aglaia Vignoli
- Child Neuropsychiatry Unit - Epilepsy Center, San Paolo Hospital, Milan, Italy.,Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
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9
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Kilisch M, Mayer S, Mitkovski M, Roehse H, Hentrich J, Schwappach B, Papadopoulos T. A GTPase-induced switch in phospholipid affinity of collybistin contributes to synaptic gephyrin clustering. J Cell Sci 2020; 133:jcs.232835. [PMID: 31932505 DOI: 10.1242/jcs.232835] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 12/19/2019] [Indexed: 11/20/2022] Open
Abstract
Synaptic transmission between neurons relies on the exact spatial organization of postsynaptic transmitter receptors, which are recruited and positioned by dedicated scaffolding and regulatory proteins. At GABAergic synapses, the regulatory protein collybistin (Cb, also known as ARHGEF9) interacts with small GTPases, cell adhesion proteins and phosphoinositides to recruit the scaffolding protein gephyrin and GABAA receptors to nascent synapses. We dissected the interaction of Cb with the small Rho-like GTPase TC10 (also known as RhoQ) and phospholipids. Our data define a protein-lipid interaction network that controls the clustering of gephyrin at synapses. Within this network, TC10 and monophosphorylated phosphoinositides, particulary phosphatidylinositol 3-phosphate (PI3P), provide a coincidence detection platform that allows the accumulation and activation of Cb in endomembranes. Upon activation, TC10 induces a phospholipid affinity switch in Cb, which allows Cb to specifically interact with phosphoinositide species present at the plasma membrane. We propose that this GTPase-based regulatory switch mechanism represents an important step in the process of tethering of Cb-dependent scaffolds and receptors at nascent postsynapses.
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Affiliation(s)
- Markus Kilisch
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, Göttingen 37073, Germany
| | - Simone Mayer
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein Str. 3, Göttingen 37075, Germany
| | - Miso Mitkovski
- MPI-EM Light Microscopy Facility, Max Planck Institute of Experimental Medicine, Hermann-Rein Str. 3, Göttingen 37075, Germany
| | - Heiko Roehse
- MPI-EM Light Microscopy Facility, Max Planck Institute of Experimental Medicine, Hermann-Rein Str. 3, Göttingen 37075, Germany
| | - Jennifer Hentrich
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, Göttingen 37073, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, Göttingen 37073, Germany
| | - Theofilos Papadopoulos
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, Göttingen 37073, Germany
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Khayenko V, Maric HM. Targeting GABA AR-Associated Proteins: New Modulators, Labels and Concepts. Front Mol Neurosci 2019; 12:162. [PMID: 31293385 PMCID: PMC6606717 DOI: 10.3389/fnmol.2019.00162] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022] Open
Abstract
γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review article, we introduce a new strategy to modulate GABAeric signaling: targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with submicron resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.
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Affiliation(s)
- Vladimir Khayenko
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Hans Michael Maric
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
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