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Certain N, Gan Q, Bennett J, Hsieh H, Wollmuth LP. Differential regulation of tetramerization of the AMPA receptor glutamate-gated ion channel by auxiliary subunits. J Biol Chem 2023; 299:105227. [PMID: 37673338 PMCID: PMC10558804 DOI: 10.1016/j.jbc.2023.105227] [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: 02/21/2023] [Revised: 08/21/2023] [Accepted: 08/24/2023] [Indexed: 09/08/2023] Open
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) auxiliary subunits are specialized, nontransient binding partners of AMPARs that modulate AMPAR channel gating properties and pharmacology, as well as their biogenesis and trafficking. The most well-characterized families of auxiliary subunits are transmembrane AMPAR regulatory proteins (TARPs), cornichon homologs (CNIHs), and the more recently discovered GSG1-L. These auxiliary subunits can promote or reduce surface expression of AMPARs (composed of GluA1-4 subunits) in neurons, thereby impacting their functional role in membrane signaling. Here, we show that CNIH-2 enhances the tetramerization of WT and mutant AMPARs, presumably by increasing the overall stability of the tetrameric complex, an effect that is mainly mediated by interactions with the transmembrane domain of the receptor. We also find CNIH-2 and CNIH-3 show receptor subunit-specific actions in this regard with CNIH-2 enhancing both GluA1 and GluA2 tetramerization, whereas CNIH-3 only weakly enhances GluA1 tetramerization. These results are consistent with the proposed role of CNIHs as endoplasmic reticulum cargo transporters for AMPARs. In contrast, TARP γ-2, TARP γ-8, and GSG1-L have no or negligible effect on AMPAR tetramerization. On the other hand, TARP γ-2 can enhance receptor tetramerization but only when directly fused with the receptor at a maximal stoichiometry. Notably, surface expression of functional AMPARs was enhanced by CNIH-2 to a greater extent than TARP γ-2, suggesting that this distinction aids in maturation and membrane expression. These experiments define a functional distinction between CNIHs and other auxiliary subunits in the regulation of AMPAR biogenesis.
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Affiliation(s)
- Noele Certain
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, USA
| | - Quan Gan
- Graduate Program in Neuroscience, Stony Brook University, Stony Brook, New York, USA
| | - Joseph Bennett
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, New York, USA
| | - Helen Hsieh
- Department of Surgery, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA; Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York, USA
| | - Lonnie P Wollmuth
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, New York, USA; Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York, USA; Department of Biochemistry & Cell Biology, Stony Brook University, Stony Brook, New York, USA.
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2
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Xiang J, Guo J, Zhang S, Wu H, Chen YG, Wang J, Li B, Liu H. A stromal lineage maintains crypt structure and villus homeostasis in the intestinal stem cell niche. BMC Biol 2023; 21:169. [PMID: 37553612 PMCID: PMC10408166 DOI: 10.1186/s12915-023-01667-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 07/24/2023] [Indexed: 08/10/2023] Open
Abstract
BACKGROUND The nutrient-absorbing villi of small intestines are renewed and repaired by intestinal stem cells (ISCs), which reside in a well-organized crypt structure. Genetic studies have shown that Wnt molecules secreted by telocytes, Gli1+ stromal cells, and epithelial cells are required for ISC proliferation and villus homeostasis. Intestinal stromal cells are heterogeneous and single-cell profiling has divided them into telocytes/subepithelial myofibroblasts, myocytes, pericytes, trophocytes, and Pdgfralow stromal cells. Yet, the niche function of these stromal populations remains incompletely understood. RESULTS We show here that a Twist2 stromal lineage, which constitutes the Pdgfralow stromal cell and trophocyte subpopulations, maintains the crypt structure to provide an inflammation-restricting niche for regenerating ISCs. Ablating Twist2 lineage cells or deletion of one Wntless allele in these cells disturbs the crypt structure and impairs villus homeostasis. Upon radiation, Wntless haplo-deficiency caused decreased production of anti-microbial peptides and increased inflammation, leading to defective ISC proliferation and crypt regeneration, which were partially rescued by eradication of commensal bacteria. In addition, we show that Wnts secreted by Acta2+ subpopulations also play a role in crypt regeneration but not homeostasis. CONCLUSIONS These findings suggest that ISCs may require different niches for villus homeostasis and regeneration and that the Twist2 lineage cells may help to maintain a microbe-restricted environment to allow ISC-mediated crypt regeneration.
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Affiliation(s)
- Jinnan Xiang
- The Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200024, China
| | - Jigang Guo
- The Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200024, China
| | - Shaoyang Zhang
- The Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200024, China
| | - Hongguang Wu
- The Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200024, China
| | - Ye-Guang Chen
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Junping Wang
- Chongqing Engineering Research Center for Nanomedicine, College of Preventive Medicine, Third Military Medical University, Chongqing, China
| | - Baojie Li
- The Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200024, China.
| | - Huijuan Liu
- The Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200024, China.
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3
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Abstract
Intercellular communication by Wnt proteins governs many essential processes during development, tissue homeostasis and disease in all metazoans. Many context-dependent effects are initiated in the Wnt-producing cells and depend on the export of lipidated Wnt proteins. Although much focus has been on understanding intracellular Wnt signal transduction, the cellular machinery responsible for Wnt secretion became better understood only recently. After lipid modification by the acyl-transferase Porcupine, Wnt proteins bind their dedicated cargo protein Evi/Wntless for transport and secretion. Evi/Wntless and Porcupine are conserved transmembrane proteins, and their 3D structures were recently determined. In this Review, we summarise studies and structural data highlighting how Wnts are transported from the ER to the plasma membrane, and the role of SNX3-retromer during the recycling of its cargo receptor Evi/Wntless. We also describe the regulation of Wnt export through a post-translational mechanism and review the importance of Wnt secretion for organ development and cancer, and as a future biomarker.
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Affiliation(s)
- Lucie Wolf
- German Cancer Research Center (DKFZ), Division of Signalling and Functional Genomics and Heidelberg University, BioQuant and Department of Cell and Molecular Biology, 69120 Heidelberg, Germany
| | - Michael Boutros
- German Cancer Research Center (DKFZ), Division of Signalling and Functional Genomics and Heidelberg University, BioQuant and Department of Cell and Molecular Biology, 69120 Heidelberg, Germany
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4
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Fuhrmann S, Ramirez S, Mina Abouda M, Campbell CD. Porcn is essential for growth and invagination of the mammalian optic cup. Front Cell Dev Biol 2022; 10:1016182. [PMID: 36393832 PMCID: PMC9661423 DOI: 10.3389/fcell.2022.1016182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 10/04/2022] [Indexed: 11/13/2022] Open
Abstract
Microphthalmia, anophthalmia, and coloboma (MAC) are congenital ocular malformations causing 25% of childhood blindness. The X-linked disorder Focal Dermal Hypoplasia (FDH) is frequently associated with MAC and results from mutations in Porcn, a membrane bound O-acyl transferase required for palmitoylation of Wnts to activate multiple Wnt-dependent pathways. Wnt/β-catenin signaling is suppressed in the anterior neural plate for initiation of eye formation and is subsequently required during differentiation of the retinal pigment epithelium (RPE). Non-canonical Wnts are critical for early eye formation in frog and zebrafish. However, it is unclear whether this also applies to mammals. We performed ubiquitous conditional inactivation of Porcn in mouse around the eye field stage. In Porcn CKO , optic vesicles (OV) arrest in growth and fail to form an optic cup. Ventral proliferation is significantly decreased in the mutant OV, with a concomitant increase in apoptotic cell death. While pan-ocular transcription factors such as PAX6, SIX3, LHX2, and PAX2 are present, indicative of maintenance of OV identity, regional expression of VSX2, MITF, OTX2, and NR2F2 is downregulated. Failure of RPE differentiation in Porcn CKO is consistent with downregulation of the Wnt/β-catenin effector LEF1, starting around 2.5 days after inactivation. This suggests that Porcn inactivation affects signaling later than a potential requirement for Wnts to promote eye field formation. Altogether, our data shows a novel requirement for Porcn in regulating growth and morphogenesis of the OV, likely by controlling proliferation and survival. In FDH patients with ocular manifestations, growth deficiency during early ocular morphogenesis may be the underlying cause for microphthalmia.
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Affiliation(s)
- Sabine Fuhrmann
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Cell and Developmental Biology, Vanderbilt University Medical School, Nashville, TN, United States
| | - Sara Ramirez
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
- Department of Cell and Developmental Biology, Vanderbilt University Medical School, Nashville, TN, United States
| | - Mirna Mina Abouda
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Clorissa D. Campbell
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, TN, United States
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5
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Arredondo SB, Valenzuela-Bezanilla D, Santibanez SH, Varela-Nallar L. Wnt signaling in the adult hippocampal neurogenic niche. Stem Cells 2022; 40:630-640. [PMID: 35446432 DOI: 10.1093/stmcls/sxac027] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 03/29/2022] [Indexed: 11/14/2022]
Abstract
The subgranular zone (SGZ) of the hippocampal dentate gyrus (DG) is a neurogenic niche of the adult brain that contains neural stem cells (NSCs) able to generate excitatory glutamatergic granule neurons, which integrate into the DG circuit and contribute to hippocampal plasticity, learning, and memory. Thus, endogenous NSCs could be harnessed for therapeutic purposes. In this context, it is critical to characterize the molecular mechanisms controlling the generation and functional integration of adult-born neurons. Adult hippocampal neurogenesis is tightly controlled by both cell-autonomous mechanisms and the interaction with the complex niche microenvironment, which harbors the NSCs and provides the signals to support their maintenance, activation, and differentiation. Among niche-derived factors, Wnt ligands play diverse roles. Wnts are secreted glycoproteins that bind to Frizzled receptors and co-receptors to trigger the Wnt signaling pathway. Here, we summarize the current knowledge about the roles of Wnts in the regulation of adult hippocampal neurogenesis. We discuss the possible contribution of the different niche cells to the regulation of local Wnt signaling activity, and how Wnts derived from different cell types could induce differential effects. Finally, we discuss how the effects of Wnt signaling on hippocampal network activity might contribute to neurogenesis regulation. Although the evidence supports relevant roles for Wnt signaling in adult hippocampal neurogenesis, defining the cellular source and the mechanisms controlling secretion and diffusion of Wnts will be crucial to further understand Wnt signaling regulation of adult NSCs, and eventually, to propose this pathway as a therapeutic target to promote neurogenesis.
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Affiliation(s)
- Sebastian B Arredondo
- Institute of Biomedical Sciences, Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Echaurren 183, 8370071, Santiago, Chile
| | - Daniela Valenzuela-Bezanilla
- Institute of Biomedical Sciences, Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Echaurren 183, 8370071, Santiago, Chile
| | - Sebastian H Santibanez
- Institute of Biomedical Sciences, Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Echaurren 183, 8370071, Santiago, Chile
| | - Lorena Varela-Nallar
- Institute of Biomedical Sciences, Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Echaurren 183, 8370071, Santiago, Chile
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6
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Kalantary-Charvadeh A, Hosseini V, Mehdizadeh A, Nazari Soltan Ahmad S, Rahbarghazi R, Nozad Charoudeh H, Nouri M, Darabi M. The porcupine inhibitor WNT974 provokes ectodermal lineage differentiation of human embryonic stem cells. Cell Biochem Funct 2022; 40:359-368. [PMID: 35445405 DOI: 10.1002/cbf.3700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/04/2022] [Accepted: 03/10/2022] [Indexed: 11/08/2022]
Abstract
Porcupine (Porcn) enzyme plays an essential role in Wnt signaling activation. Stearoyl-CoA desaturase-1 (SCD1) is required to provide Porcn substrates. The aim of this study was to determine the effect of a novel Porcn inhibitor on the fate of human embryonic stem cells (hESCs) and the reliance of Porcn on SCD1 activity. hESCs were cultured on a feeder layer or Matrigel-coated plates. Small molecules WNT974 (LGK-974) and CAY10566 were used to inhibit Porcn and SCD1 activity, respectively. We assessed the effect of Porcn inhibition on viability, expression of Wnt signaling targets, pluripotency markers, proliferation, differentiation, and protein fatty acylation. hESCs' conditioned medium (CM) containing secreted Wnt proteins were applied in rescue experiments. To examine the catalytic dependency of Porcn on SCD1, the results of combined inhibitor treatment were compared with the SCD1 inhibitor alone. LGK-974 at the selected concentrations showed mild effects on hESCs viability, but significantly reduced messenger RNA and protein expression of Wnt signaling targets (Axin-2 and c-Myc) and pluripotency markers (OCT-4 and SOX-2) (p < .05). Adding 1 μM of Porcn inhibitor reduced proliferation (p = .03) and enhanced differentiation capacity into ectodermal progenitors (p = .02), which were reverted by CM. Click chemistry reaction did not show significant alteration in protein fatty acylation upon LGK-974 treatment. Moreover, combined inhibitor treatment caused no further substantial reduction in Wnt signaling targets, pluripotency markers, and protein fatty acylation relative to CAY10566-treated cultures. The substrate availability for Porcn activity is regulated by SCD1 and targeting Porcn by LGK-974 prompts the transition of hESCs from self-renewal state to ectodermal lineage.
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Affiliation(s)
- Ashkan Kalantary-Charvadeh
- Department of Biochemistry and Clinical Laboratories, Tabriz University of Medical Sciences, Tabriz, Iran.,Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Vahid Hosseini
- Molecular Medicine Research Center, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Amir Mehdizadeh
- Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Saeed Nazari Soltan Ahmad
- Department of Biochemistry and Clinical Laboratories, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Reza Rahbarghazi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Hojjatollah Nozad Charoudeh
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammad Nouri
- Department of Biochemistry and Clinical Laboratories, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Masoud Darabi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.,Molecular Cell Biology Laboratory, Internal Medicine IV, University of Heidelberg, Heidelberg, Germany
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7
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Arlt A, Kohlschmidt N, Hentschel A, Bartels E, Groß C, Töpf A, Edem P, Szabo N, Sickmann A, Meyer N, Schara-Schmidt U, Lau J, Lochmüller H, Horvath R, Oktay Y, Roos A, Hiz S. Novel insights into PORCN mutations, associated phenotypes and pathophysiological aspects. Orphanet J Rare Dis 2022; 17:29. [PMID: 35101074 PMCID: PMC8802438 DOI: 10.1186/s13023-021-02068-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 09/30/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Goltz syndrome (GS) is a X-linked disorder defined by defects of mesodermal- and ectodermal-derived structures and caused by PORCN mutations. Features include striated skin-pigmentation, ocular and skeletal malformations and supernumerary or hypoplastic nipples. Generally, GS is associated with in utero lethality in males and most of the reported male patients show mosaicism (only three non-mosaic surviving males have been described so far). Also, precise descriptions of neurological deficits in GS are rare and less severe phenotypes might not only be caused by mosaicism but also by less pathogenic mutations suggesting the need of a molecular genetics and functional work-up of these rare variants. RESULTS We report two cases: one girl suffering from typical skin and skeletal abnormalities, developmental delay, microcephaly, thin corpus callosum, periventricular gliosis and drug-resistant epilepsy caused by a PORCN nonsense-mutation (c.283C > T, p.Arg95Ter). Presence of these combined neurological features indicates that CNS-vulnerability might be a guiding symptom in the diagnosis of GS patients. The other patient is a boy with a supernumerary nipple and skeletal anomalies but also, developmental delay, microcephaly, cerebral atrophy with delayed myelination and drug-resistant epilepsy as predominant features. Skin abnormalities were not observed. Genotyping revealed a novel PORCN missense-mutation (c.847G > C, p.Asp283His) absent in the Genome Aggregation Database (gnomAD) but also identified in his asymptomatic mother. Given that non-random X-chromosome inactivation was excluded in the mother, fibroblasts of the index had been analyzed for PORCN protein-abundance and -distribution, vulnerability against additional ER-stress burden as well as for protein secretion revealing changes. CONCLUSIONS Our combined findings may suggest incomplete penetrance for the p.Asp283His variant and provide novel insights into the molecular etiology of GS by adding impaired ER-function and altered protein secretion to the list of pathophysiological processes resulting in the clinical manifestation of GS.
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Affiliation(s)
- Annabelle Arlt
- Institute of Clinical Genetics and Tumor Genetics, Bonn, Germany
| | | | | | - Enrika Bartels
- Institute of Clinical Genetics and Tumor Genetics, Bonn, Germany
| | - Claudia Groß
- Institute of Clinical Genetics and Tumor Genetics, Bonn, Germany
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Pınar Edem
- Department of Medical Biology, School of Medicine, Dokuz Eylul University, Izmir, Turkey
| | - Nora Szabo
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK
| | - Albert Sickmann
- Leibniz Institute for Analytical Sciences (ISAS), Dortmund, Germany
| | - Nancy Meyer
- Pediatric Neurology, Faculty of Medicine, University of Duisburg-Essen, University Hospital, Essen, Germany
| | - Ulrike Schara-Schmidt
- Pediatric Neurology, Faculty of Medicine, University of Duisburg-Essen, University Hospital, Essen, Germany
| | - Jarred Lau
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
- Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK
| | - Yavuz Oktay
- Department of Medical Biology, School of Medicine, Dokuz Eylul University, Izmir, Turkey
- Izmir Biomedicine and Genome Center, Dokuz Eylul University Health Campus, Izmir, Turkey
- Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, Izmir, Turkey
| | - Andreas Roos
- Department of Clinical Neurosciences, University of Cambridge School of Clinical Medicine, Cambridge Biomedical Campus, Cambridge, UK.
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada.
| | - Semra Hiz
- Izmir Biomedicine and Genome Center, Dokuz Eylul University Health Campus, Izmir, Turkey
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8
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Yeung JHY, Walby JL, Palpagama TH, Turner C, Waldvogel HJ, Faull RLM, Kwakowsky A. Glutamatergic receptor expression changes in the Alzheimer's disease hippocampus and entorhinal cortex. Brain Pathol 2021; 31:e13005. [PMID: 34269494 PMCID: PMC8549033 DOI: 10.1111/bpa.13005] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/25/2021] [Accepted: 06/21/2021] [Indexed: 11/29/2022] Open
Abstract
Alzheimer's Disease (AD) is the leading form of dementia worldwide. Currently, the pathological mechanisms underlying AD are not well understood. Although the glutamatergic system is extensively implicated in its pathophysiology, there is a gap in knowledge regarding the expression of glutamate receptors in the AD brain. This study aimed to characterize the expression of specific glutamate receptor subunits in post‐mortem human brain tissue using immunohistochemistry and confocal microscopy. Free‐floating immunohistochemistry and confocal laser scanning microscopy were used to quantify the density of glutamate receptor subunits GluA2, GluN1, and GluN2A in specific cell layers of the hippocampal sub‐regions, subiculum, entorhinal cortex, and superior temporal gyrus. Quantification of GluA2 expression in human post‐mortem hippocampus revealed a significant increase in the stratum (str.) moleculare of the dentate gyrus (DG) in AD compared with control. Increased GluN1 receptor expression was found in the str. moleculare and hilus of the DG, str. oriens of the CA2 and CA3, str. pyramidale of the CA2, and str. radiatum of the CA1, CA2, and CA3 subregions and the entorhinal cortex. GluN2A expression was significantly increased in AD compared with control in the str. oriens, str. pyramidale, and str. radiatum of the CA1 subregion. These findings indicate that the expression of glutamatergic receptor subunits shows brain region‐specific changes in AD, suggesting possible pathological receptor functioning. These results provide evidence of specific glutamatergic receptor subunit changes in the AD hippocampus and entorhinal cortex, indicating the requirement for further research to elucidate the pathophysiological mechanisms it entails, and further highlight the potential of glutamatergic receptor subunits as therapeutic targets.
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Affiliation(s)
- Jason H Y Yeung
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Joshua L Walby
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Thulani H Palpagama
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Clinton Turner
- Department of Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Richard L M Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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9
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Matthews PM, Pinggera A, Kampjut D, Greger IH. Biology of AMPA receptor interacting proteins - From biogenesis to synaptic plasticity. Neuropharmacology 2021; 197:108709. [PMID: 34271020 DOI: 10.1016/j.neuropharm.2021.108709] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/19/2021] [Accepted: 07/08/2021] [Indexed: 12/19/2022]
Abstract
AMPA-type glutamate receptors mediate the majority of excitatory synaptic transmission in the central nervous system. Their signaling properties and abundance at synapses are both crucial determinants of synapse efficacy and plasticity, and are therefore under sophisticated control. Unique to this ionotropic glutamate receptor (iGluR) is the abundance of interacting proteins that contribute to its complex regulation. These include transient interactions with the receptor cytoplasmic tail as well as the N-terminal domain locating to the synaptic cleft, both of which are involved in AMPAR trafficking and receptor stabilization at the synapse. Moreover, an array of transmembrane proteins operate as auxiliary subunits that in addition to receptor trafficking and stabilization also substantially impact AMPAR gating and pharmacology. Here, we provide an overview of the catalogue of AMPAR interacting proteins, and how they contribute to the complex biology of this central glutamate receptor.
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Affiliation(s)
- Peter M Matthews
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Alexandra Pinggera
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Domen Kampjut
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
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10
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Parrilla-Carrero J, Eid M, Li H, Chao YS, Jhou TC. Synaptic Adaptations at the Rostromedial Tegmental Nucleus Underlie Individual Differences in Cocaine Avoidance Behavior. J Neurosci 2021; 41:4620-4630. [PMID: 33753546 PMCID: PMC8260244 DOI: 10.1523/jneurosci.1847-20.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 02/07/2021] [Accepted: 03/02/2021] [Indexed: 11/21/2022] Open
Abstract
Although cocaine is powerfully rewarding, not all individuals are equally prone to abusing this drug. We postulate that these differences arise in part because some individuals exhibit stronger aversive responses to cocaine that protect them from cocaine seeking. Indeed, using conditioned place preference (CPP) and a runway operant cocaine self-administration task, we demonstrate that avoidance responses to cocaine vary greatly between individual high cocaine-avoider and low cocaine-avoider rats. These behavioral differences correlated with cocaine-induced activation of the rostromedial tegmental nucleus (RMTg), measured using both in vivo firing and c-fos, whereas slice electrophysiological recordings from ventral tegmental area (VTA)-projecting RMTg neurons showed that relative to low avoiders, high avoiders exhibited greater intrinsic excitability, greater transmission via calcium-permeable AMPA receptors (CP-AMPARs), and higher presynaptic glutamate release. In behaving animals, blocking CP-AMPARs in the RMTg with NASPM reduced cocaine avoidance. Hence, cocaine addiction vulnerability may be linked to multiple coordinated synaptic differences in VTA-projecting RMTg neurons.SIGNIFICANCE STATEMENT Although cocaine is highly addictive, not all individuals exposed to cocaine progress to chronic use for reasons that remain unclear. We find that cocaine's aversive effects, although less widely studied than its rewarding effects, show more individual variability, are predictive of subsequent propensity to seek cocaine, and are driven by variations in RMTg in response to cocaine that arise from distinct alterations in intrinsic excitability and glutamate transmission onto VTA-projecting RMTg neurons.
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Affiliation(s)
- Jeffrey Parrilla-Carrero
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Maya Eid
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Hao Li
- Salk Institute for Biological Studies, La Jolla, California 92037
| | - Ying S Chao
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Thomas C Jhou
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425
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11
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Salm EJ, Dunn PJ, Shan L, Yamasaki M, Malewicz NM, Miyazaki T, Park J, Sumioka A, Hamer RRL, He WW, Morimoto-Tomita M, LaMotte RH, Tomita S. TMEM163 Regulates ATP-Gated P2X Receptor and Behavior. Cell Rep 2021; 31:107704. [PMID: 32492420 DOI: 10.1016/j.celrep.2020.107704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 04/14/2020] [Accepted: 05/06/2020] [Indexed: 12/18/2022] Open
Abstract
Fast purinergic signaling is mediated by ATP and ATP-gated ionotropic P2X receptors (P2XRs), and it is implicated in pain-related behaviors. The properties exhibited by P2XRs vary between those expressed in heterologous cells and in vivo. Several modulators of ligand-gated ion channels have recently been identified, suggesting that there are P2XR functional modulators in vivo. Here, we establish a genome-wide open reading frame (ORF) collection and perform functional screening to identify modulators of P2XR activity. We identify TMEM163, which specifically modulates the channel properties and pharmacology of P2XRs. We also find that TMEM163 is required for full function of the neuronal P2XR and a pain-related ATP-evoked behavior. These results establish TMEM163 as a critical modulator of P2XRs in vivo and a potential target for the discovery of drugs for treating pain.
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Affiliation(s)
- Elizabeth J Salm
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Patrick J Dunn
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Lili Shan
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Miwako Yamasaki
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Nathalie M Malewicz
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Taisuke Miyazaki
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Joongkyu Park
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Akio Sumioka
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | - Wei-Wu He
- OriGene Technologies, Inc., Rockville, MD 20850, USA
| | - Megumi Morimoto-Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Robert H LaMotte
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, The Yale Kavli Institute, Yale University School of Medicine, New Haven, CT 06520, USA; Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, CT 06520, USA.
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12
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Miralpeix C, Reguera AC, Fosch A, Casas M, Lillo J, Navarro G, Franco R, Casas J, Alexander SPH, Casals N, Rodríguez-Rodríguez R. Carnitine palmitoyltransferase 1C negatively regulates the endocannabinoid hydrolase ABHD6 in mice, depending on nutritional status. Br J Pharmacol 2021; 178:1507-1523. [PMID: 33444462 PMCID: PMC9328656 DOI: 10.1111/bph.15377] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 11/09/2020] [Accepted: 11/13/2020] [Indexed: 01/05/2023] Open
Abstract
Background and Purpose The enzyme α/β‐hydrolase domain containing 6 (ABHD6), a new member of the endocannabinoid system, is a promising therapeutic target against neuronal‐related diseases. However, how ABHD6 activity is regulated is not known. ABHD6 coexists in protein complexes with the brain‐specific carnitine palmitoyltransferase 1C (CPT1C). CPT1C is involved in neuro‐metabolic functions, depending on brain malonyl–CoA levels. Our aim was to study CPT1C–ABHD6 interaction and determine whether CPT1C is a key regulator of ABHD6 activity depending on nutritional status. Experimental Approach Co‐immunoprecipitation and FRET assays were used to explore ABHD6 interaction with CPT1C or modified malonyl–CoA‐insensitive or C‐terminal truncated CPT1C forms. Cannabinoid CB1 receptor‐mediated signalling was investigated by determining cAMP levels. A novel highly sensitive fluorescent method was optimized to measure ABHD6 activity in non‐neuronal and neuronal cells and in brain tissues from wild‐type (WT) and CPT1C–KO mice. Key Results CPT1C interacted with ABHD6 and negatively regulated its hydrolase activity, thereby regulating 2‐AG downstream signalling. Accordingly, brain tissues of CPT1C–KO mice showed increased ABHD6 activity. CPT1C malonyl–CoA sensing was key to the regulatory role on ABHD6 activity and CB1 receptor signalling. Fasting, which attenuates brain malonyl–CoA, significantly increased ABHD6 activity in hypothalamus from WT, but not CPT1C–KO, mice. Conclusions and Implications Our finding that negative regulation of ABHD6 activity, particularly in the hypothalamus, is sensitive to nutritional status throws new light on the characterization and the importance of the proteins involved as potential targets against diseases affecting the CNS.
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Affiliation(s)
- Cristina Miralpeix
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain.,INSERM, Neurocentre Magendie, University of Bordeaux, Bordeaux, France
| | - Ana Cristina Reguera
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - Anna Fosch
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
| | - Maria Casas
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain.,Department of Physiology and Membrane Biology, University of California, Davis, Davis, California, USA
| | - Jaume Lillo
- Molecular Neurobiology Laboratory, Department of Biochemistry and Physiology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Gemma Navarro
- INSERM, Neurocentre Magendie, University of Bordeaux, Bordeaux, France
| | - Rafael Franco
- INSERM, Neurocentre Magendie, University of Bordeaux, Bordeaux, France
| | - Josefina Casas
- Department on Biomedical Chemistry, Research Unit of BioActive Molecules, Institut de Química Avançada de Catalunya (IQAC), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Instituto de Salud Carlos III, Madrid, Spain
| | | | - Núria Casals
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain.,Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Rosalía Rodríguez-Rodríguez
- Basic Sciences Department, Faculty of Medicine and Health Sciences, Universitat Internacional de Catalunya, Sant Cugat del Vallès, Spain
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13
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Auth JM, Nachstedt T, Tetzlaff C. The Interplay of Synaptic Plasticity and Scaling Enables Self-Organized Formation and Allocation of Multiple Memory Representations. Front Neural Circuits 2020; 14:541728. [PMID: 33117130 PMCID: PMC7575689 DOI: 10.3389/fncir.2020.541728] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 08/19/2020] [Indexed: 12/23/2022] Open
Abstract
It is commonly assumed that memories about experienced stimuli are represented by groups of highly interconnected neurons called cell assemblies. This requires allocating and storing information in the neural circuitry, which happens through synaptic weight adaptations at different types of synapses. In general, memory allocation is associated with synaptic changes at feed-forward synapses while memory storage is linked with adaptation of recurrent connections. It remains, however, largely unknown how memory allocation and storage can be achieved and the adaption of the different synapses involved be coordinated to allow for a faithful representation of multiple memories without disruptive interference between them. In this theoretical study, by using network simulations and phase space analyses, we show that the interplay between long-term synaptic plasticity and homeostatic synaptic scaling organizes simultaneously the adaptations of feed-forward and recurrent synapses such that a new stimulus forms a new memory and where different stimuli are assigned to distinct cell assemblies. The resulting dynamics can reproduce experimental in-vivo data, focusing on how diverse factors, such as neuronal excitability and network connectivity, influence memory formation. Thus, the here presented model suggests that a few fundamental synaptic mechanisms may suffice to implement memory allocation and storage in neural circuitry.
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Affiliation(s)
- Johannes Maria Auth
- Department of Computational Neuroscience, Third Institute of Physics, Georg-August-Universität, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, Göttingen, Germany
| | - Timo Nachstedt
- Department of Computational Neuroscience, Third Institute of Physics, Georg-August-Universität, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, Göttingen, Germany
| | - Christian Tetzlaff
- Department of Computational Neuroscience, Third Institute of Physics, Georg-August-Universität, Göttingen, Germany
- Bernstein Center for Computational Neuroscience, Göttingen, Germany
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14
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Wei M, Wang M, Wang J, Su F, Wang Y, Sun M, Wang S, Liu M, Wang H, Lu M, Li W, Gong Y, Yang L, Zhang C. PORCN Negatively Regulates AMPAR Function Independently of Subunit Composition and the Amino-Terminal and Carboxy-Terminal Domains of AMPARs. Front Cell Dev Biol 2020; 8:829. [PMID: 32984326 PMCID: PMC7477090 DOI: 10.3389/fcell.2020.00829] [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: 06/15/2020] [Accepted: 08/04/2020] [Indexed: 11/13/2022] Open
Abstract
Most fast excitatory synaptic transmissions in the mammalian brain are mediated by α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs), which are ligand-gated cation channels. The membrane expression level of AMPARs is largely determined by auxiliary subunits in AMPAR macromolecules, including porcupine O-acyltransferase (PORCN), which negatively regulates AMPAR trafficking to the plasma membrane. However, whether PORCN-mediated regulation depends on AMPAR subunit composition or particular regions of a subunit has not been determined. We systematically examined the effects of PORCN on the ligand-gated current and surface expression level of GluA1, GluA2, and GluA3 AMPAR subunits, alone and in combination, as well as the PORCN-GluA interaction in heterologous HEK293T cells. PORCN inhibited glutamate-induced currents and the surface expression of investigated GluA AMPAR subunits in a subunit-independent manner. These inhibitory effects required neither the amino-terminal domain (ATD) nor the carboxy-terminal domain (CTD) of GluA subunits. In addition, PORCN interacted with AMPARs independently of their ATD or CTD. Thus, the functional inhibition of AMPARs by PORCN in transfected heterologous cells was independent of the ATD, CTD, and subunit composition of AMPARs.
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Affiliation(s)
- Mengping Wei
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Meng Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Jue Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Feng Su
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China.,Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yangzhen Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Meng Sun
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Shanshan Wang
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Mengna Liu
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Hongyi Wang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Mingyang Lu
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Wei Li
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Yutian Gong
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Lei Yang
- Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
| | - Chen Zhang
- PKU-IDG/McGovern Institute for Brain Research, School of Life Sciences, Peking University, Beijing, China.,Beijing Key Laboratory of Neural Regeneration and Repair, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China
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15
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Schwenk J, Fakler B. Building of AMPA‐type glutamate receptors in the endoplasmic reticulum and its implication for excitatory neurotransmission. J Physiol 2020; 599:2639-2653. [DOI: 10.1113/jp279025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 07/21/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jochen Schwenk
- Institute of Physiology, Faculty of Medicine University of Freiburg Hermann‐Herder‐Str. 7 Freiburg 79104 Germany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine University of Freiburg Hermann‐Herder‐Str. 7 Freiburg 79104 Germany
- Signalling Research Centres BIOSS and CIBSS Schänzlestr. 18 Freiburg 79104 Germany
- Center for Basics in NeuroModulation Breisacherstr. 4 Freiburg 79106 Germany
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16
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Kamalova A, Nakagawa T. AMPA receptor structure and auxiliary subunits. J Physiol 2020; 599:453-469. [PMID: 32004381 DOI: 10.1113/jp278701] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 01/28/2020] [Indexed: 11/08/2022] Open
Abstract
Fast excitatory synaptic transmission in the mammalian brain is largely mediated by AMPA-type ionotropic glutamate receptors (AMPARs), which are activated by the neurotransmitter glutamate. In synapses, the function of AMPARs is tuned by their auxiliary subunits, a diverse set of membrane proteins associated with the core pore-forming subunits of the AMPARs. Each auxiliary subunit provides distinct functional modulation of AMPARs, ranging from regulation of trafficking to shaping ion channel gating kinetics. Understanding the molecular mechanism of the function of these complexes is key to decoding synaptic modulation and their global roles in cognitive activities, such as learning and memory. Here, we review the structural and molecular complexity of AMPAR-auxiliary subunit complexes, as well as their functional diversity in different brain regions. We suggest that the recent structural information provides new insights into the molecular mechanisms underlying synaptic functions of AMPAR-auxiliary subunit complexes.
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Affiliation(s)
- Aichurok Kamalova
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA.,Center for Structural Biology, Vanderbilt University, School of Medicine, Nashville, TN, 37232, USA
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17
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An ER Assembly Line of AMPA-Receptors Controls Excitatory Neurotransmission and Its Plasticity. Neuron 2019; 104:680-692.e9. [DOI: 10.1016/j.neuron.2019.08.033] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 06/28/2019] [Accepted: 08/20/2019] [Indexed: 11/15/2022]
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18
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Twomey EC, Yelshanskaya MV, Sobolevsky AI. Structural and functional insights into transmembrane AMPA receptor regulatory protein complexes. J Gen Physiol 2019; 151:1347-1356. [PMID: 31615831 PMCID: PMC6888759 DOI: 10.1085/jgp.201812264] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 09/26/2019] [Indexed: 11/20/2022] Open
Abstract
Twomey et al. examine recent structural and functional data that have provided insight into AMPA receptor modulation by TARPs. Fast excitatory neurotransmission is mediated by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype of ionotropic glutamate receptor (AMPAR). AMPARs initiate depolarization of the postsynaptic neuron by allowing cations to enter through their ion channel pores in response to binding of the neurotransmitter glutamate. AMPAR function is dramatically affected by auxiliary subunits, which are regulatory proteins that form various complexes with AMPARs throughout the brain. The most well-studied auxiliary subunits are the transmembrane AMPAR regulatory proteins (TARPs), which alter the assembly, trafficking, localization, kinetics, and pharmacology of AMPARs. Recent structural and functional studies of TARPs and the TARP-fold germ cell-specific gene 1-like (GSG1L) subunit have provided important glimpses into how auxiliary subunits regulate the function of synaptic complexes. In this review, we put these recent structures in the context of new functional findings in order to gain insight into the determinants of AMPAR regulation by TARPs. We thus reveal why TARPs display a broad range of effects despite their conserved modular architecture.
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Affiliation(s)
- Edward C Twomey
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY
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19
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Bissen D, Foss F, Acker-Palmer A. AMPA receptors and their minions: auxiliary proteins in AMPA receptor trafficking. Cell Mol Life Sci 2019; 76:2133-2169. [PMID: 30937469 PMCID: PMC6502786 DOI: 10.1007/s00018-019-03068-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 02/12/2019] [Accepted: 03/07/2019] [Indexed: 12/12/2022]
Abstract
To correctly transfer information, neuronal networks need to continuously adjust their synaptic strength to extrinsic stimuli. This ability, termed synaptic plasticity, is at the heart of their function and is, thus, tightly regulated. In glutamatergic neurons, synaptic strength is controlled by the number and function of AMPA receptors at the postsynapse, which mediate most of the fast excitatory transmission in the central nervous system. Their trafficking to, at, and from the synapse, is, therefore, a key mechanism underlying synaptic plasticity. Intensive research over the last 20 years has revealed the increasing importance of interacting proteins, which accompany AMPA receptors throughout their lifetime and help to refine the temporal and spatial modulation of their trafficking and function. In this review, we discuss the current knowledge about the roles of key partners in regulating AMPA receptor trafficking and focus especially on the movement between the intracellular, extrasynaptic, and synaptic pools. We examine their involvement not only in basal synaptic function, but also in Hebbian and homeostatic plasticity. Included in our review are well-established AMPA receptor interactants such as GRIP1 and PICK1, the classical auxiliary subunits TARP and CNIH, and the newest additions to AMPA receptor native complexes.
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Affiliation(s)
- Diane Bissen
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
- Max Planck Institute for Brain Research, Max von Laue Str. 4, 60438, Frankfurt am Main, Germany
| | - Franziska Foss
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany
| | - Amparo Acker-Palmer
- Institute of Cell Biology and Neuroscience and Buchmann Institute for Molecular Life Sciences (BMLS), University of Frankfurt, Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
- Max Planck Institute for Brain Research, Max von Laue Str. 4, 60438, Frankfurt am Main, Germany.
- Cardio-Pulmonary Institute (CPI), Max-von-Laue-Str. 15, 60438, Frankfurt am Main, Germany.
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20
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AMPA Receptor Auxiliary Proteins of the CKAMP Family. Int J Mol Sci 2019; 20:ijms20061460. [PMID: 30909450 PMCID: PMC6470934 DOI: 10.3390/ijms20061460] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/12/2019] [Accepted: 03/14/2019] [Indexed: 12/26/2022] Open
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are assembled of four core subunits and several additional interacting proteins. Cystine-knot AMPA receptor-modulating proteins (CKAMPs) constitute a family of four proteins that influence the trafficking, subcellular localization and function of AMPA receptors. The four CKAMP family members CKAMP39/shisa8, CKAMP44/shisa9, CKAMP52/shisa6 and CKAMP59/shisa7 differ in their expression profile and their modulatory influence on AMPA receptor function. In this review, I report about recent findings on the differential roles of CKAMP family members.
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21
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Stewart M, Lau P, Banks G, Bains RS, Castroflorio E, Oliver PL, Dixon CL, Kruer MC, Kullmann DM, Acevedo-Arozena A, Wells SE, Corrochano S, Nolan PM. Loss of Frrs1l disrupts synaptic AMPA receptor function, and results in neurodevelopmental, motor, cognitive and electrographical abnormalities. Dis Model Mech 2019; 12:dmm.036806. [PMID: 30692144 PMCID: PMC6398485 DOI: 10.1242/dmm.036806] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/16/2019] [Indexed: 01/09/2023] Open
Abstract
Loss-of-function mutations in a human AMPA receptor-associated protein, ferric chelate reductase 1-like (FRRS1L), are associated with a devastating neurological condition incorporating choreoathetosis, cognitive deficits and epileptic encephalopathies. Furthermore, evidence from overexpression and ex vivo studies has implicated FRRS1L in AMPA receptor biogenesis, suggesting that changes in glutamatergic signalling might underlie the disorder. Here, we investigated the neurological and neurobehavioural correlates of the disorder using a mouse Frrs1l null mutant. The study revealed several neurological defects that mirrored those seen in human patients. We established that mice lacking Frrs1l suffered from a broad spectrum of early-onset motor deficits with no progressive, age-related deterioration. Moreover, Frrs1l−/− mice were hyperactive, irrespective of test environment, exhibited working memory deficits and displayed significant sleep fragmentation. Longitudinal electroencephalographic (EEG) recordings also revealed abnormal EEG results in Frrs1l−/− mice. Parallel investigations into disease aetiology identified a specific deficiency in AMPA receptor levels in the brain of Frrs1l−/− mice, while the general levels of several other synaptic components remained unchanged, with no obvious alterations in the number of synapses. Furthermore, we established that Frrsl1 deletion results in an increased proportion of immature AMPA receptors, indicated by incomplete glycosylation of GLUA2 (also known as GRIA2) and GLUA4 (also known as GRIA4) AMPA receptor proteins. This incomplete maturation leads to cytoplasmic retention and a reduction of those specific AMPA receptor levels in the postsynaptic membrane. Overall, this study determines, for the first time in vivo, how loss of FRRS1L function can affect glutamatergic signalling, and provides mechanistic insight into the development and progression of a human hyperkinetic disorder. This article has an associated First Person interview with the first author of the paper. Summary: Loss of the epilepsy-related gene Frrs1l in mice causes a dramatic reduction in AMPA receptor levels at the synapse, eliciting severe motor and coordination disabilities, hyperactivity and cognitive defects, with some evidence of behavioural seizures.
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Affiliation(s)
| | - Petrina Lau
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | - Gareth Banks
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | | | | | - Peter L Oliver
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | - Christine L Dixon
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Michael C Kruer
- Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ 85013, USA
| | - Dimitri M Kullmann
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Abraham Acevedo-Arozena
- Unidad de Investigación Hospital Universitario de Canarias, La Laguna 38320, Spain.,ITB, Universidad de La Laguna, La Laguna 38320, Spain.,Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), La Laguna 38320, Spain
| | - Sara E Wells
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
| | | | - Patrick M Nolan
- MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK
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22
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Mölders A, Koch A, Menke R, Klöcker N. Heterogeneity of the astrocytic AMPA-receptor transcriptome. Glia 2018; 66:2604-2616. [PMID: 30370555 DOI: 10.1002/glia.23514] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 07/01/2018] [Accepted: 07/18/2018] [Indexed: 11/06/2022]
Abstract
Astrocytes form the largest class of glial cells in the central nervous system. They serve plenty of diverse functions that range from supporting the formation and proper operation of synapses to controlling the blood-brain barrier. For many of them, the expression of ionotropic glutamate receptors of the AMPA subtype (AMPARs) in astrocytes is of key importance. AMPARs form as macromolecular protein complexes, whose composition of the pore-lining GluA subunits and of an extensive set of core and peripheral complex constituents defines both their trafficking and gating behavior. Although astrocytic AMPARs have been reported to exhibit heterogeneous properties, their molecular composition is largely unknown. In this study, we sought to quantify the astrocytic AMPAR transcriptome during brain development and with respect to selected brain regions. Whereas the early postnatal pattern of AMPAR mRNA expression showed minor variation over time, it did show significant heterogeneity in different brain regions. Cerebellar astrocytes express a combination of AMPAR complex constituents that is remarkably distinct from the one in neocortical or hippocampal astrocytes. Our study provides a workflow and a first reference for future investigations into the molecular and functional diversity of glial AMPARs.
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Affiliation(s)
- Andrea Mölders
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Angela Koch
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Raphael Menke
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
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23
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Jacobi E, von Engelhardt J. AMPA receptor complex constituents: Control of receptor assembly, membrane trafficking and subcellular localization. Mol Cell Neurosci 2018; 91:67-75. [DOI: 10.1016/j.mcn.2018.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 05/15/2018] [Accepted: 05/24/2018] [Indexed: 11/29/2022] Open
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24
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Gratacòs-Batlle E, Olivella M, Sánchez-Fernández N, Yefimenko N, Miguez-Cabello F, Fadó R, Casals N, Gasull X, Ambrosio S, Soto D. Mechanisms of CPT1C-Dependent AMPAR Trafficking Enhancement. Front Mol Neurosci 2018; 11:275. [PMID: 30135643 PMCID: PMC6092487 DOI: 10.3389/fnmol.2018.00275] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 07/20/2018] [Indexed: 12/19/2022] Open
Abstract
In neurons, AMPA receptor (AMPAR) function depends essentially on their constituent components:the ion channel forming subunits and ion channel associated proteins. On the other hand, AMPAR trafficking is tightly regulated by a vast number of intracellular neuronal proteins that bind to AMPAR subunits. It has been recently shown that the interaction between the GluA1 subunit of AMPARs and carnitine palmitoyltransferase 1C (CPT1C), a novel protein partner of AMPARs, is important in modulating surface expression of these ionotropic glutamate receptors. Indeed, synaptic transmission in CPT1C knockout (KO) mice is diminished supporting a positive trafficking role for that protein. However, the molecular mechanisms of such modulation remain unknown although a putative role of CPT1C in depalmitoylating GluA1 has been hypothesized. Here, we explore that possibility and show that CPT1C effect on AMPARs is likely due to changes in the palmitoylation state of GluA1. Based on in silico analysis, Ser 252, His 470 and Asp 474 are predicted to be the catalytic triad responsible for CPT1C palmitoyl thioesterase (PTE) activity. When these residues are mutated or when PTE activity is inhibited, the CPT1C effect on AMPAR trafficking is abolished, validating the CPT1C catalytic triad as being responsible for PTE activity on AMPAR. Moreover, the histidine residue (His 470) of CPT1C is crucial for the increase in GluA1 surface expression in neurons and the H470A mutation impairs the depalmitoylating catalytic activity of CPT1C. Finally, we show that CPT1C effect seems to be specific for this CPT1 isoform and it takes place solely at endoplasmic reticulum (ER). This work adds another facet to the impressive degree of molecular mechanisms regulating AMPAR physiology.
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Affiliation(s)
- Esther Gratacòs-Batlle
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Mireia Olivella
- Grup de Recerca en Bioinformàtica i Estadística Mèdica, Universitat de Vic, Barcelona, Spain
| | - Nuria Sánchez-Fernández
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Natalia Yefimenko
- Laboratori de Neurobiologia, Department de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, Campus Universitari de Bellvitge, Universitat de Barcelona, Barcelona, Spain
| | - Federico Miguez-Cabello
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Rut Fadó
- Department de Ciències Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Barcelona, Spain
| | - Núria Casals
- Department de Ciències Bàsiques, Facultat de Medicina i Ciències de la Salut, Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Instituto de Salud Carlos III, Barcelona, Spain
| | - Xavier Gasull
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Santiago Ambrosio
- Unitat de Bioquímica, Departament de Ciències Fisiològiques, Facultat de Medicina i Ciències de la Salut, Campus Universitari de Bellvitge, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques de Bellvitge (IDIBELL), Barcelona, Spain
| | - David Soto
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
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25
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Matt L, Kirk LM, Chenaux G, Speca DJ, Puhger KR, Pride MC, Qneibi M, Haham T, Plambeck KE, Stern-Bach Y, Silverman JL, Crawley JN, Hell JW, Díaz E. SynDIG4/Prrt1 Is Required for Excitatory Synapse Development and Plasticity Underlying Cognitive Function. Cell Rep 2018; 22:2246-2253. [PMID: 29490264 PMCID: PMC5856126 DOI: 10.1016/j.celrep.2018.02.026] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/15/2017] [Accepted: 02/06/2018] [Indexed: 11/19/2022] Open
Abstract
Altering AMPA receptor (AMPAR) content at synapses is a key mechanism underlying the regulation of synaptic strength during learning and memory. Previous work demonstrated that SynDIG1 (synapse differentiation-induced gene 1) encodes a transmembrane AMPAR-associated protein that regulates excitatory synapse strength and number. Here we show that the related protein SynDIG4 (also known as Prrt1) modifies AMPAR gating properties in a subunit-dependent manner. Young SynDIG4 knockout (KO) mice have weaker excitatory synapses, as evaluated by immunocytochemistry and electrophysiology. Adult SynDIG4 KO mice show complete loss of tetanus-induced long-term potentiation (LTP), while mEPSC amplitude is reduced by only 25%. Furthermore, SynDIG4 KO mice exhibit deficits in two independent cognitive assays. Given that SynDIG4 colocalizes with the AMPAR subunit GluA1 at non-synaptic sites, we propose that SynDIG4 maintains a pool of extrasynaptic AMPARs necessary for synapse development and function underlying higher-order cognitive plasticity.
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Affiliation(s)
- Lucas Matt
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - Lyndsey M Kirk
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - George Chenaux
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - David J Speca
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA
| | - Kyle R Puhger
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Michael C Pride
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Mohammad Qneibi
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Tomer Haham
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | | | - Yael Stern-Bach
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Jill L Silverman
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Jacqueline N Crawley
- MIND Institute, Department of Psychiatry and Behavioral Sciences, UC Davis School of Medicine, Sacramento, CA 95817, USA
| | - Johannes W Hell
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA.
| | - Elva Díaz
- Department of Pharmacology, UC Davis School of Medicine, Davis, CA 95616, USA.
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26
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Abstract
There are significant challenges in identifying receptor-specific functional interactors in vivo. In this issue of Neuron, Ge et al. (2018) identify a novel GABAA receptor (GABAAR)-interacting protein, Clptm1, that regulates forward trafficking of GABAARs and inhibitory transmission.
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Affiliation(s)
- Yoav Noam
- Department of Cellular and Molecular Physiology, Department of Neuroscience, CNNR program, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, CNNR program, Yale University School of Medicine, New Haven, CT 06520, USA.
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27
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Glaeser K, Urban M, Fenech E, Voloshanenko O, Kranz D, Lari F, Christianson JC, Boutros M. ERAD-dependent control of the Wnt secretory factor Evi. EMBO J 2018; 37:embj.201797311. [PMID: 29378775 PMCID: PMC5813261 DOI: 10.15252/embj.201797311] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 12/01/2017] [Accepted: 01/02/2018] [Indexed: 12/21/2022] Open
Abstract
Active regulation of protein abundance is an essential strategy to modulate cellular signaling pathways. Within the Wnt signaling cascade, regulated degradation of β-catenin by the ubiquitin-proteasome system (UPS) affects the outcome of canonical Wnt signaling. Here, we found that abundance of the Wnt cargo receptor Evi (Wls/GPR177), which is required for Wnt protein secretion, is also regulated by the UPS through endoplasmic reticulum (ER)-associated degradation (ERAD). In the absence of Wnt ligands, Evi is ubiquitinated and targeted for ERAD in a VCP-dependent manner. Ubiquitination of Evi involves the E2-conjugating enzyme UBE2J2 and the E3-ligase CGRRF1. Furthermore, we show that a triaging complex of Porcn and VCP determines whether Evi enters the secretory or the ERAD pathway. In this way, ERAD-dependent control of Evi availability impacts the scale of Wnt protein secretion by adjusting the amount of Evi to meet the requirement of Wnt protein export. As Wnt and Evi protein levels are often dysregulated in cancer, targeting regulatory ERAD components might be a useful approach for therapeutic interventions.
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Affiliation(s)
- Kathrin Glaeser
- Division of Signaling and Functional Genomics, German Cancer Research Center (DKFZ) and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Manuela Urban
- Division of Signaling and Functional Genomics, German Cancer Research Center (DKFZ) and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Emma Fenech
- Ludwig Institute for Cancer Research, University of Oxford, Oxford, UK
| | - Oksana Voloshanenko
- Division of Signaling and Functional Genomics, German Cancer Research Center (DKFZ) and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Dominique Kranz
- Division of Signaling and Functional Genomics, German Cancer Research Center (DKFZ) and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Federica Lari
- Ludwig Institute for Cancer Research, University of Oxford, Oxford, UK
| | | | - Michael Boutros
- Division of Signaling and Functional Genomics, German Cancer Research Center (DKFZ) and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
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28
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Han W, Wang H, Li J, Zhang S, Lu W. Ferric Chelate Reductase 1 Like Protein (FRRS1L) Associates with Dynein Vesicles and Regulates Glutamatergic Synaptic Transmission. Front Mol Neurosci 2017; 10:402. [PMID: 29276473 PMCID: PMC5727121 DOI: 10.3389/fnmol.2017.00402] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/20/2017] [Indexed: 12/23/2022] Open
Abstract
In the brain, AMPA receptors (AMPARs)-mediated excitatory synaptic transmission is critically regulated by the receptor auxiliary subunits. Recent proteomic studies have identified that Ferric Chelate Reductase 1 Like protein (FRRS1L), whose mutations in human lead to epilepsy, choreoathetosis, and cognitive deficits, is present in native AMPAR complexes in the brain. Here we have characterized FRRS1L in both heterologous cells and in mouse neurons. We found that FRRS1L interacts with both GluA1 and GluA2 subunits of AMPARs, but does not form dimers/oligomers, in HEK cells. In mouse hippocampal neurons, recombinant FRRS1L at the neuronal surface partially co-localizes with GluA1 and primarily localizes at non-synaptic membranes. In addition, native FRRS1L in hippocampus is localized at dynein, but not kinesin5B, vesicles. Functionally, over-expression of FRRS1L in hippocampal neurons does not change glutamatergic synaptic transmission. In contrast, single-cell knockout (KO) of FRRS1L strongly reduces the expression levels of the GluA1 subunit at the neuronal surface, and significantly decreases AMPAR-mediated synaptic transmission in mouse hippocampal pyramidal neurons. Taken together, these data characterize FRRS1L in heterologous cells and neurons, and reveal an important role of FRRS1L in the regulation of excitatory synaptic strength.
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Affiliation(s)
- Wenyan Han
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Huiqing Wang
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States.,Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.,Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jun Li
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Shizhong Zhang
- Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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29
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Schmitz LJM, Klaassen RV, Ruiperez-Alonso M, Zamri AE, Stroeder J, Rao-Ruiz P, Lodder JC, van der Loo RJ, Mansvelder HD, Smit AB, Spijker S. The AMPA receptor-associated protein Shisa7 regulates hippocampal synaptic function and contextual memory. eLife 2017; 6:24192. [PMID: 29199957 PMCID: PMC5737659 DOI: 10.7554/elife.24192] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 12/02/2017] [Indexed: 12/20/2022] Open
Abstract
Glutamatergic synapses rely on AMPA receptors (AMPARs) for fast synaptic transmission and plasticity. AMPAR auxiliary proteins regulate receptor trafficking, and modulate receptor mobility and its biophysical properties. The AMPAR auxiliary protein Shisa7 (CKAMP59) has been shown to interact with AMPARs in artificial expression systems, but it is unknown whether Shisa7 has a functional role in glutamatergic synapses. We show that Shisa7 physically interacts with synaptic AMPARs in mouse hippocampus. Shisa7 gene deletion resulted in faster AMPAR currents in CA1 synapses, without affecting its synaptic expression. Shisa7 KO mice showed reduced initiation and maintenance of long-term potentiation of glutamatergic synapses. In line with this, Shisa7 KO mice showed a specific deficit in contextual fear memory, both short-term and long-term after conditioning, whereas auditory fear memory and anxiety-related behavior were normal. Thus, Shisa7 is a bona-fide AMPAR modulatory protein affecting channel kinetics of AMPARs, necessary for synaptic hippocampal plasticity, and memory recall.
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Affiliation(s)
- Leanne J M Schmitz
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.,Sylics (Synaptologics BV), Amsterdam, The Netherlands
| | - Remco V Klaassen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Marta Ruiperez-Alonso
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Azra Elia Zamri
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.,Université de Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, Bordeaux, France
| | - Jasper Stroeder
- Sylics (Synaptologics BV), Amsterdam, The Netherlands.,Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Priyanka Rao-Ruiz
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Johannes C Lodder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Rolinka J van der Loo
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.,Sylics (Synaptologics BV), Amsterdam, The Netherlands
| | - Huib D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - Sabine Spijker
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
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30
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Kato AS, Witkin JM. Auxiliary subunits of AMPA receptors: The discovery of a forebrain-selective antagonist, LY3130481/CERC-611. Biochem Pharmacol 2017; 147:191-200. [PMID: 28987594 DOI: 10.1016/j.bcp.2017.09.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 09/27/2017] [Indexed: 12/11/2022]
Abstract
Drugs originate from the discovery of compounds, natural or synthetic, that bind to proteins (receptors, enzymes, transporters, etc.), the interaction of which modulates biological cascades that have potential therapeutic benefit. Rational strategies for identifying novel drug therapies are typically based on knowledge of the structure of the target proteins and the design of new chemical entities that modulate these proteins in a beneficial manner. The present review discusses a novel approach to drug discovery based on the identification and characterization of auxiliary proteins, the transmembrane AMPA receptor regulatory proteins (TARPs) that are associated with AMPA receptors. Utilizing these auxiliary proteins in compound screening led to the discovery of the TARP-dependent-AMPA forebrain selective receptor antagonist (TDAA), LY3130481/CERC-611 that is currently in clinical development for epilepsy.
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Affiliation(s)
- Akihiko S Kato
- Neuroscience Discovery Research, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN 46285-0510, United States.
| | - Jeffrey M Witkin
- Neuroscience Discovery Research, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN 46285-0510, United States.
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31
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Poursharifi P, Madiraju SRM, Prentki M. Monoacylglycerol signalling and ABHD6 in health and disease. Diabetes Obes Metab 2017; 19 Suppl 1:76-89. [PMID: 28880480 DOI: 10.1111/dom.13008] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 04/24/2017] [Accepted: 05/11/2017] [Indexed: 12/14/2022]
Abstract
Lipid metabolism dysregulation underlies chronic pathologies such as obesity, diabetes and cancer. Besides their role in structure and energy storage, lipids are also important signalling molecules regulating multiple biological functions. Thus, understanding the precise lipid metabolism enzymatic steps that are altered in some pathological conditions is helpful for designing better treatment strategies. Several monoacylglycerol (MAG) species are only recently being recognized as signalling lipid molecules in different tissues. Recent studies indicated the importance of the ubiquitously expressed serine hydrolase α/β-hydrolase domain 6 (ABHD6), which is a MAG hydrolase, in regulating signalling competent MAG in both central and peripheral tissues. The central and peripheral function of the endocannabinoid 2-arachidonoylglycerol, which is a 2-MAG, and its breakdown by both ABHD6 and classical MAG lipase has been well documented. ABHD6 and its substrate MAG appear to be involved in the regulation of various physiological and pathological processes including insulin secretion, adipose browning, food intake, neurotransmission, autoimmune disorders, neurological and metabolic diseases as well as cancer. Diverse cellular targets such as mammalian unc13-1 (Munc13-1), PPARs, GPR119 and CB1/2 receptors, for MAG-mediated signalling processes have been proposed in different cell types. The purpose of this review is to provide a comprehensive summary of the current state of knowledge regarding ABHD6/MAG signalling and its possible therapeutic implications.
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Affiliation(s)
- Pegah Poursharifi
- Departments of Nutrition, Biochemistry and Molecular Medicine, University of Montreal, and Montreal Diabetes Research Center, CRCHUM, Montreal, Canada
| | - Sri Ramachandra Murthy Madiraju
- Departments of Nutrition, Biochemistry and Molecular Medicine, University of Montreal, and Montreal Diabetes Research Center, CRCHUM, Montreal, Canada
| | - Marc Prentki
- Departments of Nutrition, Biochemistry and Molecular Medicine, University of Montreal, and Montreal Diabetes Research Center, CRCHUM, Montreal, Canada
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32
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Diversity in AMPA receptor complexes in the brain. Curr Opin Neurobiol 2017; 45:32-38. [DOI: 10.1016/j.conb.2017.03.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/28/2017] [Accepted: 03/03/2017] [Indexed: 11/23/2022]
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33
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Bettler B, Fakler B. Ionotropic AMPA-type glutamate and metabotropic GABAB receptors: determining cellular physiology by proteomes. Curr Opin Neurobiol 2017; 45:16-23. [DOI: 10.1016/j.conb.2017.02.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/15/2017] [Indexed: 02/07/2023]
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34
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Baucum AJ. Proteomic Analysis of Postsynaptic Protein Complexes Underlying Neuronal Plasticity. ACS Chem Neurosci 2017; 8:689-701. [PMID: 28211672 DOI: 10.1021/acschemneuro.7b00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Normal neuronal communication and synaptic plasticity at glutamatergic synapses requires dynamic regulation of postsynaptic molecules. Protein expression and protein post-translational modifications regulate protein interactions that underlie this organization. In this Review, we highlight data obtained over the last 20 years that have used qualitative and quantitative proteomics-based approaches to identify postsynaptic protein complexes. Herein, we describe how these proteomics studies have helped lay the foundation for understanding synaptic physiology and perturbations in synaptic signaling observed in different pathologies. We also describe emerging technologies that can be useful in these analyses. We focus on protein complexes associated with the highly abundant and functionally critical proteins: calcium/calmodulin-dependent protein kinase II, the N-methyl-d-aspartate, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors, and postsynaptic density protein of 95 kDa.
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Affiliation(s)
- Anthony J. Baucum
- Department of Biology, Stark Neurosciences
Research Institute, Indiana University-Purdue University Indianapolis, 723 W. Michigan St., Indianapolis, Indiana 46202, United States
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35
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Wei M, Jia M, Zhang J, Yu L, Zhao Y, Chen Y, Ma Y, Zhang W, Shi YS, Zhang C. The Inhibitory Effect of α/β-Hydrolase Domain-Containing 6 (ABHD6) on the Surface Targeting of GluA2- and GluA3-Containing AMPA Receptors. Front Mol Neurosci 2017; 10:55. [PMID: 28303090 PMCID: PMC5333494 DOI: 10.3389/fnmol.2017.00055] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 02/17/2017] [Indexed: 01/16/2023] Open
Abstract
The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) are major excitatory receptors that mediate fast neurotransmission in the mammalian brain. The surface expression of functional AMPARs is crucial for synaptic transmission and plasticity. AMPAR auxiliary subunits control the biosynthesis, membrane trafficking, and synaptic targeting of AMPARs. Our previous report showed that α/β-hydrolase domain-containing 6 (ABHD6), an auxiliary subunit for AMPARs, suppresses the membrane delivery and function of GluA1-containing receptors in both heterologous cells and neurons. However, it remained unclear whether ABHD6 affects the membrane trafficking of glutamate receptor subunits, GluA2 and GluA3. Here, we examine the effects of ABHD6 overexpression in HEK293T cells expressing GluA1, GluA2, GluA3, and stargazin, either alone or in combination. The results show that ABHD6 suppresses the glutamate-induced currents and the membrane expression of AMPARs when expressing GluA2 or GluA3 in the HEK293T cells. We generated a series of GluA2 and GluA3 C-terminal deletion constructs and confirm that the C-terminus of GluAs is required for ABHD6’s inhibitory effects on glutamate-induced currents and surface expression of GluAs. Meanwhile, our pull-down experiments reveal that ABHD6 binds to GluA1–3, and deletion of the C-terminal domain of GluAs abolishes this binding. These findings demonstrate that ABHD6 inhibits the AMPAR-mediated currents and its surface expression, independent of the type of AMPAR subunits, and this inhibitor’s effects are mediated through the binding with the GluAs C-terminal regions.
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Affiliation(s)
- Mengping Wei
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Moye Jia
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Jian Zhang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Lulu Yu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Yunzhi Zhao
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Yingqi Chen
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Yimeng Ma
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
| | - Wei Zhang
- Department of Pharmacology, Institute of Chinese Integrative Medicine, Hebei Medical University Shijiazhuang, China
| | - Yun S Shi
- Ministry of Education (MOE) Key Laboratory of Model Animal for Disease Study, Model Animal Research Center of Nanjing University Nanjing, China
| | - Chen Zhang
- State Key Laboratory of Membrane Biology, School of Life Sciences, Peking UniversityBeijing, China; PKU-IDG (International Digital Group)/McGovern Institute for Brain Research, Peking UniversityBeijing, China
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Rex EB, Shukla N, Gu S, Bredt D, DiSepio D. A Genome-Wide Arrayed cDNA Screen to Identify Functional Modulators of α7 Nicotinic Acetylcholine Receptors. SLAS DISCOVERY 2016; 22:155-165. [PMID: 27789755 DOI: 10.1177/1087057116676086] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cellular signaling is in part regulated by the composition and subcellular localization of a series of protein interactions that collectively form a signaling complex. Using the α7 nicotinic acetylcholine receptor (α7nAChR) as a proof-of-concept target, we developed a platform to identify functional modulators (or auxiliary proteins) of α7nAChR signaling. The Broad cDNA library was transiently cotransfected with α7nAChR cDNA in HEK293T cells in a high-throughput fashion. Using this approach in combination with a functional assay, we identified positive modulators of α7nAChR activity. We identified known positive modulators/auxiliary proteins present in the cDNA library that regulate α7nAChR signaling, in addition to identifying novel modulators of α7nAChR signaling. These included NACHO, SPDYE11, TCF4, and ZC3H12A, all of which increased PNU-120596-mediated nicotine-dependent calcium flux. Importantly, these auxiliary proteins did not modulate GluR1(o)-mediated Ca flux. To elucidate a possible mechanism of action, we employed an α7nAChR-HA surface staining assay. NACHO enhanced α7nAChR surface expression; however, the mechanism responsible for the SPDYE11-, TCF4-, and ZC3H12A-dependent modulation of α7nAChR has yet to be defined. This report describes the development and validation of a high-throughput, genome-wide cDNA screening platform coupled to FLIPR functional assays in order to identify functional modulators of α7nAChR signaling.
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Affiliation(s)
- Elizabeth B Rex
- 1 Discovery Sciences, Janssen Research and Development LLC, La Jolla, CA, USA
| | - Nikhil Shukla
- 1 Discovery Sciences, Janssen Research and Development LLC, La Jolla, CA, USA
| | - Shenyan Gu
- 2 Neuroscience, Janssen Research and Development LLC, La Jolla, CA, USA
| | - David Bredt
- 2 Neuroscience, Janssen Research and Development LLC, La Jolla, CA, USA
| | - Daniel DiSepio
- 1 Discovery Sciences, Janssen Research and Development LLC, La Jolla, CA, USA
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Mao X, Gu X, Lu W. GSG1L regulates the strength of AMPA receptor-mediated synaptic transmission but not AMPA receptor kinetics in hippocampal dentate granule neurons. J Neurophysiol 2016; 117:28-35. [PMID: 27707810 DOI: 10.1152/jn.00307.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 10/03/2016] [Indexed: 11/22/2022] Open
Abstract
GSG1L is an AMPA receptor (AMPAR) auxiliary subunit that regulates AMPAR trafficking and function in hippocampal CA1 pyramidal neurons. However, its physiological roles in other types of neurons remain to be characterized. Here, we investigated the role of GSG1L in hippocampal dentate granule cells and found that GSG1L is important for the regulation of synaptic strength but is not critical for the modulation of AMPAR deactivation and desensitization kinetics. These data demonstrate a neuronal type-specific role of GSG1L and suggest that physiological function of AMPAR auxiliary subunits may vary in different types of neurons. NEW & NOTEWORTHY GSG1L is a newly identified AMPA receptor (AMPAR) auxiliary subunit and plays a unique role in the regulation of AMPAR trafficking and function in hippocampal CA1 pyramidal neurons. However, its role in the regulation of AMPARs in hippocampal dentate granule cells remains to be characterized. The current work reveals that GSG1L regulates strength of AMPAR-mediated synaptic transmission but not the receptor kinetic properties in hippocampal dentate granule neurons.
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Affiliation(s)
- Xia Mao
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Xinglong Gu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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Li TP, Blanpied TA. Control of Transmembrane Protein Diffusion within the Postsynaptic Density Assessed by Simultaneous Single-Molecule Tracking and Localization Microscopy. Front Synaptic Neurosci 2016; 8:19. [PMID: 27499742 PMCID: PMC4956670 DOI: 10.3389/fnsyn.2016.00019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 07/05/2016] [Indexed: 11/13/2022] Open
Abstract
Postsynaptic transmembrane proteins are critical elements of synapses, mediating trans-cellular contact, sensitivity to neurotransmitters and other signaling molecules, and flux of Ca and other ions. Positioning and mobility of each member of this large class of proteins is critical to their individual function at the synapse. One critical example is that the position of glutamate receptors within the postsynaptic density (PSD) strongly modulates their function by aligning or misaligning them with sites of presynaptic vesicle fusion. In addition, the regulated ability of receptors to move in or out of the synapse is critical for activity-dependent plasticity. However, factors that control receptor mobility within the boundaries of the synapse are not well understood. Notably, PSD scaffold molecules accumulate in domains much smaller than the synapse. Within these nanodomains, the density of proteins is considerably higher than that of the synapse as a whole, so high that steric hindrance is expected to reduce receptor mobility substantially. However, while numerical modeling has demonstrated several features of how the varying protein density across the face of a single PSD may modulate receptor motion, there is little experimental information about the extent of this influence. To address this critical aspect of synaptic organizational dynamics, we performed single-molecule tracking of transmembrane proteins using universal point accumulation-for-imaging-in-nanoscale-topography (uPAINT) over PSDs whose internal structure was simultaneously resolved using photoactivated localization microscopy (PALM). The results provide important experimental confirmation that PSD scaffold protein density strongly influences the mobility of transmembrane proteins. A protein with a cytosolic domain that does not bind PSD-95 was still slowed in regions of high PSD-95 density, suggesting that crowding by scaffold molecules and perhaps other proteins is sufficient to stabilize receptors even in the absence of binding. Because numerous proteins thought to be involved in establishing PSD structure are linked to disorders including autism and depression, this motivates further exploration of how PSD nanostructure is created. The combined application PALM and uPAINT should be invaluable for distinguishing the interactions of mobile proteins with their nano-environment both in synapses and other cellular compartments.
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Affiliation(s)
- Tuo P. Li
- Department of Physiology and Program in Neuroscience, University of Maryland School of MedicineBaltimore, MD, USA
| | - Thomas A. Blanpied
- Department of Physiology and Program in Neuroscience, University of Maryland School of MedicineBaltimore, MD, USA
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