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Ji Y, Izadi-Seitz M, Landmann A, Schwintzer L, Qualmann B, Kessels MM. EHBP1 Is Critically Involved in the Dendritic Arbor Formation and Is Coupled to Factors Promoting Actin Filament Formation. J Neurosci 2024; 44:e0236232023. [PMID: 38129132 PMCID: PMC10860635 DOI: 10.1523/jneurosci.0236-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 12/01/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
The coordinated action of a plethora of factors is required for the organization and dynamics of membranous structures critically underlying the development and function of cells, organs, and organisms. The evolutionary acquisition of additional amino acid motifs allows for expansion and/or specification of protein functions. We identify a thus far unrecognized motif specific for chordata EHBP1 proteins and demonstrate that this motif is critically required for interaction with syndapin I, an F-BAR domain-containing, membrane-shaping protein predominantly expressed in neurons. Gain-of-function and loss-of-function studies in rat primary hippocampal neurons (of mixed sexes) unraveled that EHBP1 has an important role in neuromorphogenesis. Surprisingly, our analyses uncovered that this newly identified function of EHBP1 did not require the domain responsible for Rab GTPase binding but was strictly dependent on EHBP1's syndapin I binding interface and on the presence of syndapin I in the developing neurons. These findings were underscored by temporally and spatially remarkable overlapping dynamics of EHBP1 and syndapin I at nascent dendritic branch sites. In addition, rescue experiments demonstrated the necessity of two additional EHBP1 domains for dendritic arborization, the C2 and CH domains. Importantly, the additionally uncovered critical involvement of the actin nucleator Cobl in EHBP1 functions suggested that not only static association with F-actin via EHBP1's CH domain is important for dendritic arbor formation but also actin nucleation. Syndapin interactions organize ternary protein complexes composed of EHBP1, syndapin I, and Cobl, and our functional data show that only together these factors give rise to proper cell shape during neuronal development.
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Affiliation(s)
- Yuanyuan Ji
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Maryam Izadi-Seitz
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Annemarie Landmann
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Lukas Schwintzer
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Michael M Kessels
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, 07743 Jena, Germany
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2
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Bai HH, Wang KL, Zeng XR, Li J, Li Y, Xu JY, Zhang Y, Jiang HF, Yang X, Suo ZW, Hu XD. GPR39 regulated spinal glycinergic inhibition and mechanical inflammatory pain. SCIENCE ADVANCES 2024; 10:eadj3808. [PMID: 38306424 PMCID: PMC10836721 DOI: 10.1126/sciadv.adj3808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 01/04/2024] [Indexed: 02/04/2024]
Abstract
G protein-coupled receptor 39 (GPR39) senses the change of extracellular divalent zinc ion and signals through multiple G proteins to a broad spectrum of downstream effectors. Here, we found that GPR39 was prevalent at inhibitory synapses of spinal cord somatostatin-positive (SOM+) interneurons, a mechanosensitive subpopulation that is critical for the conveyance of mechanical pain. GPR39 complexed specifically with inhibitory glycine receptors (GlyRs) and helped maintain glycinergic transmission in a manner independent of G protein signalings. Targeted knockdown of GPR39 in SOM+ interneurons reduced the glycinergic inhibition and facilitated the excitatory output from SOM+ interneurons to spinoparabrachial neurons that engaged superspinal neural circuits encoding both the sensory discriminative and affective motivational domains of pain experience. Our data showed that pharmacological activation of GPR39 or augmenting GPR39 interaction with GlyRs at the spinal level effectively alleviated the sensory and affective pain induced by complete Freund's adjuvant and implicated GPR39 as a promising therapeutic target for the treatment of inflammatory mechanical pain.
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Affiliation(s)
- Hu-Hu Bai
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
- School of Life Science, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Kang-Li Wang
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Xiang-Ru Zeng
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Jing Li
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Yuan Li
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Jia-Yu Xu
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Yue Zhang
- School of Public Health, Gansu University of Chinese medicine, Lanzhou, Gansu 730000, P.R. China
| | - Hai-Feng Jiang
- School of Public Health, Gansu University of Chinese medicine, Lanzhou, Gansu 730000, P.R. China
| | - Xian Yang
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Zhan-Wei Suo
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
| | - Xiao-Dong Hu
- Department of Molecular Pharmacology, School of Pharmacy, Lanzhou University, Lanzhou, Gansu 730000, P.R. China
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3
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Thompson JRE, Beaudoin CA, Lummis SCR. Modelling and Molecular Dynamics Predict the Structure and Interactions of the Glycine Receptor Intracellular Domain. Biomolecules 2023; 13:1757. [PMID: 38136628 PMCID: PMC10741472 DOI: 10.3390/biom13121757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
Glycine receptors (GlyRs) are glycine-gated inhibitory pentameric ligand-gated ion channels composed of α or α + β subunits. A number of structures of these proteins have been reported, but to date, these have only revealed details of the extracellular and transmembrane domains, with the intracellular domain (ICD) remaining uncharacterised due to its high flexibility. The ICD is a region that can modulate function in addition to being critical for receptor localisation and clustering via proteins such as gephyrin. Here, we use modelling and molecular dynamics (MD) to reveal details of the ICDs of both homomeric and heteromeric GlyR. At their N and C ends, both the α and β subunit ICDs have short helices, which are major sites of stabilising interactions; there is a large flexible loop between them capable of forming transient secondary structures. The α subunit can affect the β subunit ICD structure, which is more flexible in a 4α2:1β than in a 4α1:1β GlyR. We also explore the effects of gephyrin binding by creating GlyR models bound to the gephyrin E domain; MD simulations suggest these are more stable than the unbound forms, and again there are α subunit-dependent differences, despite the fact the gephyrin binds to the β subunit. The bound models also suggest that gephyrin causes compaction of the ICD. Overall, the data expand our knowledge of this important receptor protein and in particular clarify features of the underexplored ICD.
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Affiliation(s)
| | | | - Sarah C. R. Lummis
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
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4
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Schaefer N, Harvey RJ, Villmann C. Startle Disease: New Molecular Insights into an Old Neurological Disorder. Neuroscientist 2023; 29:767-781. [PMID: 35754344 PMCID: PMC10623600 DOI: 10.1177/10738584221104724] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Startle disease (SD) is characterized by enhanced startle responses, generalized muscle stiffness, unexpected falling, and fatal apnea episodes due to disturbed feedback inhibition in the spinal cord and brainstem of affected individuals. Mutations within the glycine receptor (GlyR) subunit and glycine transporter 2 (GlyT2) genes have been identified in individuals with SD. Impaired inhibitory neurotransmission in SD is due to pre- and/or postsynaptic GlyR or presynaptic GlyT2 dysfunctions. Previous research has focused on mutated GlyRs and GlyT2 that impair ion channel/transporter function or trafficking. With insights provided by recently solved cryo-electron microscopy and X-ray structures of GlyRs, a detailed picture of structural transitions important for receptor gating has emerged, allowing a deeper understanding of SD at the molecular level. Moreover, studies on novel SD mutations have demonstrated a higher complexity of SD, with identification of additional clinical signs and symptoms and interaction partners representing key players for fine-tuning synaptic processes. Although our knowledge has steadily improved during the last years, changes in synaptic localization and GlyR or GlyT2 homeostasis under disease conditions are not yet completely understood. Combined proteomics, interactomics, and high-resolution microscopy techniques are required to reveal alterations in receptor dynamics at the synaptic level under disease conditions.
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Affiliation(s)
- Natascha Schaefer
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Robert J. Harvey
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore DC, Australia
- Sunshine Coast Health Institute, Birtinya, Australia
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University Hospital, Julius-Maximilians-University of Würzburg, Würzburg, Germany
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5
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Izadi M, Wolf D, Seemann E, Ori A, Schwintzer L, Steiniger F, Kessels MM, Qualmann B. Membrane shapers from two distinct superfamilies cooperate in the development of neuronal morphology. J Cell Biol 2023; 222:e202211032. [PMID: 37318382 PMCID: PMC10274853 DOI: 10.1083/jcb.202211032] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 03/27/2023] [Accepted: 05/15/2023] [Indexed: 06/16/2023] Open
Abstract
Membrane-shaping proteins are driving forces behind establishment of proper cell morphology and function. Yet, their reported structural and in vitro properties are noticeably inconsistent with many physiological membrane topology requirements. We demonstrate that dendritic arborization of neurons is powered by physically coordinated shaping mechanisms elicited by members of two distinct classes of membrane shapers: the F-BAR protein syndapin I and the N-Ank superfamily protein ankycorbin. Strikingly, membrane-tubulating activities by syndapin I, which would be detrimental during dendritic branching, were suppressed by ankycorbin. Ankycorbin's integration into syndapin I-decorated membrane surfaces instead promoted curvatures and topologies reflecting those observed physiologically. In line with the functional importance of this mechanism, ankycorbin- and syndapin I-mediated functions in dendritic arborization mutually depend on each other and on a surprisingly specific interface mediating complex formation of the two membrane shapers. These striking results uncovered cooperative and interdependent functions of members of two fundamentally different membrane shaper superfamilies as a previously unknown, pivotal principle in neuronal shape development.
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Affiliation(s)
- Maryam Izadi
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
| | - David Wolf
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
| | - Eric Seemann
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
| | - Alessandro Ori
- Leibniz Institute on Aging—Fritz Lipmann Institute, Jena, Germany
| | - Lukas Schwintzer
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
| | - Frank Steiniger
- Electron Microscopy Center, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
| | - Michael Manfred Kessels
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital—Friedrich Schiller University Jena, Jena, Germany
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6
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Gibbs E, Klemm E, Seiferth D, Kumar A, Ilca SL, Biggin PC, Chakrapani S. Conformational transitions and allosteric modulation in a heteromeric glycine receptor. Nat Commun 2023; 14:1363. [PMID: 36914669 PMCID: PMC10011588 DOI: 10.1038/s41467-023-37106-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 03/02/2023] [Indexed: 03/16/2023] Open
Abstract
Glycine Receptors (GlyRs) provide inhibitory neuronal input in the spinal cord and brainstem, which is critical for muscle coordination and sensory perception. Synaptic GlyRs are a heteromeric assembly of α and β subunits. Here we present cryo-EM structures of full-length zebrafish α1βBGlyR in the presence of an antagonist (strychnine), agonist (glycine), or agonist with a positive allosteric modulator (glycine/ivermectin). Each structure shows a distinct pore conformation with varying degrees of asymmetry. Molecular dynamic simulations found the structures were in a closed (strychnine) and desensitized states (glycine and glycine/ivermectin). Ivermectin binds at all five interfaces, but in a distinct binding pose at the β-α interface. Subunit-specific features were sufficient to solve structures without a fiduciary marker and to confirm the 4α:1β stoichiometry recently observed. We also report features of the extracellular and intracellular domains. Together, our results show distinct compositional and conformational properties of α1βGlyR and provide a framework for further study of this physiologically important channel.
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Affiliation(s)
- Eric Gibbs
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - Emily Klemm
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - David Seiferth
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Arvind Kumar
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA
| | - Serban L Ilca
- New York Structural Biology Center, New York, NY, 10027, USA
- Simons Electron Microscopy Center, New York, NY, 10027, USA
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Sudha Chakrapani
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
- Department of Neuroscience, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106-4970, USA.
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7
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Tröger J, Seemann E, Heintzmann R, Kessels MM, Qualmann B. Spinal Cord Synaptic Plasticity by GlyRβ Release from Receptor Fields and Syndapin I-Dependent Uptake. J Neurosci 2022; 42:6706-6723. [PMID: 35879097 PMCID: PMC9436020 DOI: 10.1523/jneurosci.2060-21.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 06/23/2022] [Accepted: 07/13/2022] [Indexed: 11/21/2022] Open
Abstract
Glycine receptor-mediated inhibitory neurotransmission is key for spinal cord function. Recent observations suggested that by largely elusive mechanisms also glycinergic synapses display synaptic plasticity. We imaged receptor fields at ultrahigh-resolution at freeze-fractured membranes, tracked surface and internalized glycine receptors (GlyR), and studied differential regulations of GlyRβ interactions with the scaffold protein gephyrin and the F-BAR domain protein syndapin I and thereby reveal key principles of this process. S403 phosphorylation of GlyRβ, known to be triggered by synaptic signaling, caused a decoupling from gephyrin scaffolds but simultaneously promoted association of syndapin I with GlyRβ. In line, kainate treatments used to trigger rearrangements of glycine receptors in murine syndapin I KO spinal cords (mixed sex) showed even more severe receptor field fragmentation than already observed in untreated syndapin I KO spinal cords. Syndapin I deficiency furthermore resulted in more dispersed receptors and increased receptor mobility, also pointing out an important contribution of syndapin I to the organization of GlyRβ fields. Strikingly, syndapin I KO also led to a complete disruption of kainate-induced GlyRβ internalization. Accompanying quantitative ultrahigh-resolution studies in dissociated spinal cord neurons proved that the defects in GlyR internalization observed in syndapin I KO spinal cords are neuron-intrinsic defects caused by syndapin I deficiency. Together, our results unveiled important mechanisms organizing and altering glycine receptor fields during both steady state and particularly also as a consequence of kainate-induced synaptic rearrangement - principles organizing and fine-tuning synaptic efficacy and plasticity of glycinergic synapses in the spinal cord.SIGNIFICANCE STATEMENT Initial observations suggested that also glycinergic synapses, key for spinal cord and brainstem functions, may display some form of synaptic plasticity. Imaging receptor fields at ultrahigh-resolution at freeze-fractured membranes, tracking surface and internalized glycine receptors (GlyR) and studying regulations of GlyRβ interactions, we here reveal key principles of these kainate-inducible adaptations. A switch from gephyrin-mediated receptor scaffolding to syndapin I-mediated GlyRβ scaffolding and internalization allows for modulating synaptic receptor availability. In line, kainate-induced GlyRβ internalization was completely disrupted and GlyRβ receptor fields were distorted by syndapin I KO. These results unveiled important mechanisms during both steady-state and kainate-induced alterations of synaptic GlyR fields, principles underlying synaptic efficacy and plasticity of synapses in the spinal cord.
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Affiliation(s)
- Jessica Tröger
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, Jena 07743, Germany
| | - Eric Seemann
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, Jena 07743, Germany
| | - Rainer Heintzmann
- Leibniz Institute of Photonic Technology, Jena 07745, Germany
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University, Jena 07745, Germany
| | - Michael M Kessels
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, Jena 07743, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital/Friedrich Schiller University Jena, Jena 07743, Germany
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8
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Dumont V, Lehtonen S. PACSIN proteins in vivo: Roles in development and physiology. Acta Physiol (Oxf) 2022; 234:e13783. [PMID: 34990060 PMCID: PMC9285741 DOI: 10.1111/apha.13783] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 11/15/2021] [Accepted: 01/01/2022] [Indexed: 12/22/2022]
Abstract
Protein kinase C and casein kinase substrate in neurons (PACSINs), or syndapins (synaptic dynamin‐associated proteins), are a family of proteins involved in the regulation of cell cytoskeleton, intracellular trafficking and signalling. Over the last twenty years, PACSINs have been mostly studied in the in vitro and ex vivo settings, and only in the last decade reports on their function in vivo have emerged. We first summarize the identification, structure and cellular functions of PACSINs, and then focus on the relevance of PACSINs in vivo. During development in various model organisms, PACSINs participate in diverse processes, such as neural crest cell development, gastrulation, laterality development and neuromuscular junction formation. In mouse, PACSIN2 regulates angiogenesis during retinal development and in human, PACSIN2 associates with monosomy and embryonic implantation. In adulthood, PACSIN1 has been extensively studied in the brain and shown to regulate neuromorphogenesis, receptor trafficking and synaptic plasticity. Several genetic studies suggest a role for PACSIN1 in the development of schizophrenia, which is also supported by the phenotype of mice depleted of PACSIN1. PACSIN2 plays an essential role in the maintenance of intestinal homeostasis and participates in kidney repair processes after injury. PACSIN3 is abundant in muscle tissue and necessary for caveolar biogenesis to create membrane reservoirs, thus controlling muscle function, and has been linked to certain genetic muscular disorders. The above examples illustrate the importance of PACSINs in diverse physiological or tissue repair processes in various organs, and associations to diseases when their functions are disturbed.
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Affiliation(s)
- Vincent Dumont
- Department of Pathology and Research Program for Clinical and Molecular Metabolism Faculty of Medicine University of Helsinki Helsinki Finland
| | - Sanna Lehtonen
- Department of Pathology and Research Program for Clinical and Molecular Metabolism Faculty of Medicine University of Helsinki Helsinki Finland
- Department of Pathology University of Helsinki Helsinki Finland
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9
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Izadi M, Seemann E, Schlobinski D, Schwintzer L, Qualmann B, Kessels MM. Functional interdependence of the actin nucleator Cobl and Cobl-like in dendritic arbor development. eLife 2021; 10:67718. [PMID: 34264190 PMCID: PMC8282341 DOI: 10.7554/elife.67718] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 06/30/2021] [Indexed: 12/14/2022] Open
Abstract
Local actin filament formation is indispensable for development of the dendritic arbor of neurons. We show that, surprisingly, the action of single actin filament-promoting factors was insufficient for powering dendritogenesis. Instead, this required the actin nucleator Cobl and its only evolutionary distant ancestor Cobl-like acting interdependently. This coordination between Cobl-like and Cobl was achieved by physical linkage by syndapins. Syndapin I formed nanodomains at convex plasma membrane areas at the base of protrusive structures and interacted with three motifs in Cobl-like, one of which was Ca2+/calmodulin-regulated. Consistently, syndapin I, Cobl-like’s newly identified N terminal calmodulin-binding site and the single Ca2+/calmodulin-responsive syndapin-binding motif all were critical for Cobl-like’s functions. In dendritic arbor development, local Ca2+/CaM-controlled actin dynamics thus relies on regulated and physically coordinated interactions of different F-actin formation-promoting factors and only together they have the power to bring about the sophisticated neuronal morphologies required for neuronal network formation in mammals.
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Affiliation(s)
- Maryam Izadi
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Eric Seemann
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Dirk Schlobinski
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Lukas Schwintzer
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Britta Qualmann
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
| | - Michael M Kessels
- Institute of Biochemistry I, Jena University Hospital/Friedrich-Schiller-University Jena, Jena, Germany
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10
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Minehart JA, Speer CM. A Picture Worth a Thousand Molecules-Integrative Technologies for Mapping Subcellular Molecular Organization and Plasticity in Developing Circuits. Front Synaptic Neurosci 2021; 12:615059. [PMID: 33469427 PMCID: PMC7813761 DOI: 10.3389/fnsyn.2020.615059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022] Open
Abstract
A key challenge in developmental neuroscience is identifying the local regulatory mechanisms that control neurite and synaptic refinement over large brain volumes. Innovative molecular techniques and high-resolution imaging tools are beginning to reshape our view of how local protein translation in subcellular compartments drives axonal, dendritic, and synaptic development and plasticity. Here we review recent progress in three areas of neurite and synaptic study in situ-compartment-specific transcriptomics/translatomics, targeted proteomics, and super-resolution imaging analysis of synaptic organization and development. We discuss synergies between sequencing and imaging techniques for the discovery and validation of local molecular signaling mechanisms regulating synaptic development, plasticity, and maintenance in circuits.
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Affiliation(s)
| | - Colenso M. Speer
- Department of Biology, University of Maryland, College Park, MD, United States
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11
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A Novel Glycine Receptor Variant with Startle Disease Affects Syndapin I and Glycinergic Inhibition. J Neurosci 2020; 40:4954-4969. [PMID: 32354853 DOI: 10.1523/jneurosci.2490-19.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 03/24/2020] [Accepted: 04/24/2020] [Indexed: 11/21/2022] Open
Abstract
Glycine receptors (GlyRs) are the major mediators of fast synaptic inhibition in the adult human spinal cord and brainstem. Hereditary mutations to GlyRs can lead to the rare, but potentially fatal, neuromotor disorder hyperekplexia. Most mutations located in the large intracellular domain (TM3-4 loop) of the GlyRα1 impair surface expression levels of the receptors. The novel GLRA1 mutation P366L, located in the TM3-4 loop, showed normal surface expression but reduced chloride currents, and accelerated whole-cell desensitization observed in whole-cell recordings. At the single-channel level, we observed reduced unitary conductance accompanied by spontaneous opening events in the absence of extracellular glycine. Using peptide microarrays and tandem MS-based analysis methods, we show that the proline-rich stretch surrounding P366 mediates binding to syndapin I, an F-BAR domain protein involved in membrane remodeling. The disruption of the noncanonical Src homology 3 recognition motif by P366L reduces syndapin I binding. These data suggest that the GlyRα1 subunit interacts with intracellular binding partners and may therefore play a role in receptor trafficking or synaptic anchoring, a function thus far only ascribed to the GlyRβ subunit. Hence, the P366L GlyRα1 variant exhibits a unique set of properties that cumulatively affect GlyR functionality and thus might explain the neuropathological mechanism underlying hyperekplexia in the mutant carriers. P366L is the first dominant GLRA1 mutation identified within the GlyRα1 TM3-4 loop that affects GlyR physiology without altering protein expression at the whole-cell and surface levels.SIGNIFICANCE STATEMENT We show that the intracellular domain of the inhibitory glycine receptor α1 subunit contributes to trafficking and synaptic anchoring. A proline-rich stretch in this receptor domain forms a noncanonical recognition motif important for the interaction with syndapin I (PACSIN1). The disruption of this motif, as present in a human patient with hyperekplexia led to impaired syndapin I binding. Functional analysis revealed that the altered proline-rich stretch determines several functional physiological parameters of the ion channel (e.g., faster whole-cell desensitization) reduced unitary conductance and spontaneous opening events. Thus, the proline-rich stretch from the glycine receptor α1 subunit represents a multifunctional intracellular protein motif.
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12
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van der Spek SJF, Koopmans F, Paliukhovich I, Ramsden SL, Harvey K, Harvey RJ, Smit AB, Li KW. Glycine Receptor Complex Analysis Using Immunoprecipitation-Blue Native Gel Electrophoresis-Mass Spectrometry. Proteomics 2020; 20:e1900403. [PMID: 31984645 DOI: 10.1002/pmic.201900403] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Indexed: 11/07/2022]
Abstract
The pentameric glycine receptor (GlyR), comprising the α1 and β subunits, is a major inhibitory ionotropic receptor in brainstem and spinal cord. GlyRs interact with gephyrin (GPHN), a scaffold protein that anchors the GlyR in the plasma membrane and enables it to form clusters in glycinergic postsynapses. Using an interaction proteomics approach, evidence of the ArfGEFs IQ motif and Sec7 domain 3 (IQSEC3) and IQ motif and Sec7 domain 2 (IQSEC2) as two novel synaptic proteins interacting with GlyR complexes is provided. When the affinity-isolated GlyR complexes are fractionated by blue native gel electrophoresis and characterized by mass spectrometry, GlyR α1β-GPHN appears as the most abundant complex with a molecular weight of ≈1 MDa, and GlyR α1β-GPHN-IQSEC3 as a minor protein complex of ≈1.2 MDa. A third GlyR α1β-GPHN-IQSEC2 complex exists at the lowest amount with a mass similar to the IQSEC3 containing complex. Using yeast two-hybrid it is demonstrated that IQSEC3 interacts with the GlyR complex by binding to the GPHN G domain at the N-terminal of the IQSEC3 IQ-like domain. The data provide direct evidence of the interaction of IQSEC3 with GlyR-GPHN complexes, underscoring a potential role of these ArfGEFs in the function of glycinergic synapses.
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Affiliation(s)
- Sophie J F van der Spek
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Frank Koopmans
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Iryna Paliukhovich
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Sarah L Ramsden
- Department of Pharmacology, UCL School of Pharmacy, 29-39 Brunswick square, WC1N 1AX, London, UK
| | - Kirsten Harvey
- Department of Pharmacology, UCL School of Pharmacy, 29-39 Brunswick square, WC1N 1AX, London, UK
| | - Robert J Harvey
- School of Health and Sport Sciences, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland, 4558, Australia.,Sunshine Coast Health Institute, Birtinya, Queensland, 4575, Australia
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Ka Wan Li
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
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13
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Park DI, Turck CW. Interactome Studies of Psychiatric Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1118:163-173. [PMID: 30747422 DOI: 10.1007/978-3-030-05542-4_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
High comorbidity and complexity have precluded reliable diagnostic assessment and treatment of psychiatric disorders. Impaired molecular interactions may be relevant for underlying mechanisms of psychiatric disorders but by and large remain unknown. With the help of a number of publicly available databases and various technological tools, recent research has filled the paucity of information by generating a novel dataset of psychiatric interactomes. Different technological platforms including yeast two-hybrid screen, co-immunoprecipitation-coupled with mass spectrometry-based proteomics, and transcriptomics have been widely used in combination with cellular and molecular techniques to interrogate the psychiatric interactome. Novel molecular interactions have been identified in association with different psychiatric disorders including autism spectrum disorders, schizophrenia, bipolar disorder, and major depressive disorder. However, more extensive and sophisticated interactome research needs to be conducted to overcome the current limitations such as incomplete interactome databases and a lack of functional information among components. Ultimately, integrated psychiatric interactome databases will contribute to the implementation of biomarkers and therapeutic intervention.
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Affiliation(s)
- Dong Ik Park
- Danish Research Institute of Translational Neuroscience (DANDRITE), Department of Biomedicine, Aarhus University, Aarhus, Denmark.
| | - Christoph W Turck
- Proteomics and Biomarkers, Department of Translational Research in Psychiatry, Max Planck Institute of Psychiatry, Munich, Germany
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14
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Mahadevan V, Khademullah CS, Dargaei Z, Chevrier J, Uvarov P, Kwan J, Bagshaw RD, Pawson T, Emili A, De Koninck Y, Anggono V, Airaksinen M, Woodin MA. Native KCC2 interactome reveals PACSIN1 as a critical regulator of synaptic inhibition. eLife 2017; 6:e28270. [PMID: 29028184 PMCID: PMC5640428 DOI: 10.7554/elife.28270] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/08/2017] [Indexed: 01/01/2023] Open
Abstract
KCC2 is a neuron-specific K+-Cl- cotransporter essential for establishing the Cl- gradient required for hyperpolarizing inhibition in the central nervous system (CNS). KCC2 is highly localized to excitatory synapses where it regulates spine morphogenesis and AMPA receptor confinement. Aberrant KCC2 function contributes to human neurological disorders including epilepsy and neuropathic pain. Using functional proteomics, we identified the KCC2-interactome in the mouse brain to determine KCC2-protein interactions that regulate KCC2 function. Our analysis revealed that KCC2 interacts with diverse proteins, and its most predominant interactors play important roles in postsynaptic receptor recycling. The most abundant KCC2 interactor is a neuronal endocytic regulatory protein termed PACSIN1 (SYNDAPIN1). We verified the PACSIN1-KCC2 interaction biochemically and demonstrated that shRNA knockdown of PACSIN1 in hippocampal neurons increases KCC2 expression and hyperpolarizes the reversal potential for Cl-. Overall, our global native-KCC2 interactome and subsequent characterization revealed PACSIN1 as a novel and potent negative regulator of KCC2.
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Affiliation(s)
- Vivek Mahadevan
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | | | - Zahra Dargaei
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Jonah Chevrier
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Pavel Uvarov
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Julian Kwan
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Richard D Bagshaw
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Tony Pawson
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Andrew Emili
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de QuébecQuébecCanada
- Department of Psychiatry and NeuroscienceUniversité LavalQuébecCanada
| | - Victor Anggono
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia ResearchThe University of QueenslandBrisbaneAustralia
| | - Matti Airaksinen
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Melanie A Woodin
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
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15
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Zhang Y, Ho TNT, Harvey RJ, Lynch JW, Keramidas A. Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function. Front Mol Neurosci 2017; 10:158. [PMID: 28588452 PMCID: PMC5440463 DOI: 10.3389/fnmol.2017.00158] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/08/2017] [Indexed: 11/17/2022] Open
Abstract
Glycine receptors (GlyRs) containing the α2 subunit regulate cortical interneuron migration. Disruption of the GlyR α2 subunit gene (Glra2) in mice leads to disrupted dorsal cortical progenitor homeostasis, leading to a depletion of projection neurons and moderate microcephaly in newborn mice. In humans, rare variants in GLRA2, which is located on the X chromosome, are associated with autism spectrum disorder (ASD) in the hemizygous state in males. These include a microdeletion (GLRA2∆ex8-9) and missense mutations in GLRA2 (p.N109S and p.R126Q) that impair cell-surface expression of GlyR α2, and either abolish or markedly reduce sensitivity to glycine. We report the functional characterization of a third missense variant in GLRA2 (p.R323L), associated with autism, macrocephaly, epilepsy and hypothyroidism in a female proband. Using heterosynapse and macroscopic current recording techniques, we reveal that GlyR α2R323L exhibits reduced glycine sensitivity, but significantly increased inhibitory postsynaptic current (IPSC) rise and decay times. Site-directed mutagenesis revealed that the nature of the amino acid switch at position 323 is critical for impairment of GlyR function. Single-channel recordings revealed that the conductance of α2R323Lβ channels was higher than α2β channels. Longer mean opening durations induced by p.R323L may be due to a change in the gating pathway that enhances the stability of the GlyR open state. The slower synaptic decay times, longer duration active periods and increase in conductance demonstrates that the GlyR α2 p.R323L mutation results in an overall gain of function, and that GlyR α2 mutations can be pathogenic in the heterozygous state in females.
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Affiliation(s)
- Yan Zhang
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
| | - Thi Nhu Thao Ho
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
| | - Robert J Harvey
- Department of Pharmacology, UCL School of PharmacyLondon, United Kingdom
| | - Joseph W Lynch
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia.,School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
| | - Angelo Keramidas
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
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16
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Lynch JW, Zhang Y, Talwar S, Estrada-Mondragon A. Glycine Receptor Drug Discovery. ADVANCES IN PHARMACOLOGY 2017; 79:225-253. [DOI: 10.1016/bs.apha.2017.01.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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17
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PACSIN1 regulates the dynamics of AMPA receptor trafficking. Sci Rep 2016; 6:31070. [PMID: 27488904 PMCID: PMC4973260 DOI: 10.1038/srep31070] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 07/14/2016] [Indexed: 01/29/2023] Open
Abstract
Dynamic trafficking of AMPA receptors (AMPARs) into and out of synapses plays an important role in synaptic plasticity. We previously reported that the protein kinase C and casein kinase II substrate in neurons (PACSIN) forms a complex with AMPARs through its interaction with the protein interacting with C-kinase 1 (PICK1) to regulate NMDA receptor (NMDAR)-induced AMPAR endocytosis and cerebellar long-term depression. However, the molecular mechanism by which PACSIN regulates the dynamics of AMPAR trafficking remains unclear. Using a pH-sensitive green fluorescent protein, pHluorin, tagged to the extracellular domain of the GluA2 subunit of AMPARs, we demonstrate dual roles for PACSIN1 in controlling the internalization and recycling of GluA2 after NMDAR activation. Structure and function analysis reveals a requirement for the PACSIN1 F-BAR and SH3 domains in controlling these NMDAR-dependent processes. Interestingly, the variable region, which binds to PICK1, is not essential for NMDAR-dependent GluA2 internalization and is required only for the correct recycling of AMPARs. These results indicate that PACSIN is a versatile membrane deformation protein that links the endocytic and recycling machineries essential for dynamic AMPAR trafficking in neurons.
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18
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Langlhofer G, Villmann C. The Intracellular Loop of the Glycine Receptor: It's not all about the Size. Front Mol Neurosci 2016; 9:41. [PMID: 27330534 PMCID: PMC4891346 DOI: 10.3389/fnmol.2016.00041] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 05/17/2016] [Indexed: 11/15/2022] Open
Abstract
The family of Cys-loop receptors (CLRs) shares a high degree of homology and sequence identity. The overall structural elements are highly conserved with a large extracellular domain (ECD) harboring an α-helix and 10 β-sheets. Following the ECD, four transmembrane domains (TMD) are connected by intracellular and extracellular loop structures. Except the TM3–4 loop, their length comprises 7–14 residues. The TM3–4 loop forms the largest part of the intracellular domain (ICD) and exhibits the most variable region between all CLRs. The ICD is defined by the TM3–4 loop together with the TM1–2 loop preceding the ion channel pore. During the last decade, crystallization approaches were successful for some members of the CLR family. To allow crystallization, the intracellular loop was in most structures replaced by a short linker present in prokaryotic CLRs. Therefore, no structural information about the large TM3–4 loop of CLRs including the glycine receptors (GlyRs) is available except for some basic stretches close to TM3 and TM4. The intracellular loop has been intensively studied with regard to functional aspects including desensitization, modulation of channel physiology by pharmacological substances, posttranslational modifications, and motifs important for trafficking. Furthermore, the ICD interacts with scaffold proteins enabling inhibitory synapse formation. This review focuses on attempts to define structural and functional elements within the ICD of GlyRs discussed with the background of protein-protein interactions and functional channel formation in the absence of the TM3–4 loop.
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Affiliation(s)
- Georg Langlhofer
- Institute of Clinical Neurobiology, University of Würzburg Würzburg, Germany
| | - Carmen Villmann
- Institute of Clinical Neurobiology, University of Würzburg Würzburg, Germany
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19
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Dieterich DC, Kreutz MR. Proteomics of the Synapse--A Quantitative Approach to Neuronal Plasticity. Mol Cell Proteomics 2016; 15:368-81. [PMID: 26307175 PMCID: PMC4739661 DOI: 10.1074/mcp.r115.051482] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/29/2015] [Indexed: 11/06/2022] Open
Abstract
The advances in mass spectrometry based proteomics in the past 15 years have contributed to a deeper appreciation of protein networks and the composition of functional synaptic protein complexes. However, research on protein dynamics underlying core mechanisms of synaptic plasticity in brain lag far behind. In this review, we provide a synopsis on proteomic research addressing various aspects of synaptic function. We discuss the major topics in the study of protein dynamics of the chemical synapse and the limitations of current methodology. We highlight recent developments and the future importance of multidimensional proteomics and metabolic labeling. Finally, emphasis is given on the conceptual framework of modern proteomics and its current shortcomings in the quest to gain a deeper understanding of synaptic plasticity.
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Affiliation(s)
- Daniela C Dieterich
- From the ‡Institute for Pharmacology and Toxicology, Otto-von-Guericke University Magdeburg, Germany; Research Group Neuralomics, Leibniz Institute for Neurobiology Magdeburg, Germany; ¶Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
| | - Michael R Kreutz
- §RG Neuroplasticity, Leibniz Institute for Neurobiology, Magdeburg, Germany; ¶Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.
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20
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Förstera B, a Dzaye OD, Winkelmann A, Semtner M, Benedetti B, Markovic DS, Synowitz M, Wend P, Fähling M, Junier MP, Glass R, Kettenmann H, Meier JC. Intracellular glycine receptor function facilitates glioma formation in vivo. J Cell Sci 2014; 127:3687-98. [DOI: 10.1242/jcs.146662] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The neuronal function of Cys-loop neurotransmitter receptors is established; however, their role in non-neuronal cells is poorly defined. As brain tumors accumulate the neurotransmitter glycine, we studied expression and function of glycine receptors (GlyR) in glioma cells. Human brain tumor biopsies selectively expressed GlyR subunits with nuclear import signal (NLS, α1 and α3). The mouse glioma cell line GL261 expressed GlyR α1, and knock-down of α1 protein expression impaired self-renewal capacity and tumorigenicity of GL261 glioma cells as evidenced by the neurosphere assay and GL261 cell inoculation in vivo, respectively. We furthermore show that the pronounced tumorigenic effect of GlyR α1 relies on a new intracellular signaling function that depends on the NLS region in the large cytosolic loop and impacts on GL261 glioma cell gene regulation. Stable expression of GlyR α1 and α3 loops rescued self-renewal capacity of GlyR α1 knock-down cells, which demonstrates their functional equivalence. The new intracellular signaling function identified here goes beyond the well-established role of GlyRs as neuronal ligand-gated ion channels and defines NLS-containing GlyRs as novel potential targets for brain tumor therapies.
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