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Ren Y, Luo X, Tong H, Wang S, Yan J, Lin L, Chen Y. Preliminary Study on Clinical Characteristics and Pathogenesis of IQSEC2 Mutations Patients. Pharmgenomics Pers Med 2024; 17:289-318. [PMID: 38827181 PMCID: PMC11144418 DOI: 10.2147/pgpm.s455840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 05/18/2024] [Indexed: 06/04/2024] Open
Abstract
Background The IQ motif and Sec7 domain ArfGEF 2 (IQSEC2), an X-linked gene that encodes the BRAG1 protein, is a guanine nucleotide exchange factor for the ADP ribosylation factor (ARF) protein family in the small guanosine triphosphate (GTP) binding protein. Mutations in this gene result in disorders such as intellectual disability (ID) and epilepsy. In this study, we analyze the clinical features of two patients with IQSEC2-mutation-related disease and discuss their possible pathogenesis. Methods The two patients were diagnosed with ID and epilepsy. Genetic testing was performed using whole-exome sequencing, and the three-dimensional protein structure was analyzed. UCSC Genome Browser was used to analyze the conservation of IQSEC2 in different species. We compared IQSEC2 expression in the proband families with that in a control group, as well as the expression of the postsynaptic identity protein 95 (PSD-95), synapse-associated protein 97 (SAP97), ADP ribosylation factor 6 (ARF-6), and insulin receptor substrate 53kDa (IRSP53) genes interacting with IQSEC2. Results We identified two semi-zygote mutations located in conserved positions in different species: an unreported de novo mutation, C.3576C>A (p. Tyr1192*), and a known mutation, c.2983C>T (p. Arg995Trp). IQSEC2 mutations resulted in significant changes in the predicted three-dimensional protein structure, while its expression in the two probands was significantly lower than that in the age-matched control group, and IQSEC2 expression in proband 1 was lower than that in his family members. The expression levels of PSD-95, ARF-6, and SAP97, IRSP 53, which interact with IQSEC2, were also significantly different from those in the family members and age-matched healthy children. Conclusion The clinical phenotype resulting from IQSEC2 mutations can be explained by the significant decrease in its expression, loss of function of the mutant protein, and change in the expression of related genes. Our results provide novel insights into the molecular phenotype conferred by the IQSEC2 variants.
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Affiliation(s)
- Yun Ren
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Xiaona Luo
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Haiyan Tong
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Simei Wang
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Jinbin Yan
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Longlong Lin
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
| | - Yucai Chen
- Department of Neurology, Shanghai Children’s Hospital, School of Medicine, Shanghai JiaoTong University, Shanghai, People’s Republic of China
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Shokhen M, Walikonis R, Uversky VN, Allbeck A, Zezelic C, Feldman D, Levy NS, Levy AP. Molecular modeling of ARF6 dysregulation caused by mutations in IQSEC2. J Biomol Struct Dyn 2024; 42:1268-1279. [PMID: 37078745 DOI: 10.1080/07391102.2023.2199085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 03/29/2023] [Indexed: 04/21/2023]
Abstract
IQSEC2 gene mutations are associated with epilepsy, autism, and intellectual disability. The primary function IQSEC2, mediated via its Sec 7 domain, is to act as a guanine nucleotide exchange factor for ARF6. We sought to develop a molecular model, which may explain the aberrant Sec 7 activity on ARF6 of different human IQSEC2 mutations. We integrated experimental data of IQSEC2 mutants with protein structure prediction by the RaptorX server combined with molecular modeling and molecular dynamics simulations. Normally, apocalmodulin (apoCM) binds to IQSEC2 resulting in its N-terminal fragment inhibiting access of its Sec 7 domain to ARF6. An increase in Ca2+ concentration destabilizes the interaction of IQSEC2 with apoCM and removes steric hindrance of Sec 7 binding with ARF6. Mutations at amino acid residue 350 of IQSEC2 result in loss of steric hindrance of Sec 7 binding with ARF6 leading to constitutive activation of ARF6 by Sec 7. On the other hand, a mutation at amino acid residue 359 of IQSEC2 results in constitutive hindrance of Sec 7 binding to ARF6 leading to the loss of the ability of IQSEC2 to activate ARF6. These studies provide a model for dysregulation of IQSEC2 Sec 7 activity by mutant IQSEC2 proteins.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Michael Shokhen
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Randall Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Center and Research Institute, University of South Florida, Tampa, Florida, USA
| | - Amnon Allbeck
- Department of Chemistry, Bar Ilan University, Ramat Gan, Israel
| | - Camryn Zezelic
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Danielle Feldman
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nina S Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Bai G, Li H, Qin P, Guo Y, Yang W, Lian Y, Ye F, Chen J, Wu M, Huang R, Li J, Lu Y, Zhang M. Ca2+-induced release of IQSEC2/BRAG1 autoinhibition under physiological and pathological conditions. J Cell Biol 2023; 222:e202307117. [PMID: 37787765 PMCID: PMC10548395 DOI: 10.1083/jcb.202307117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/31/2023] [Accepted: 09/14/2023] [Indexed: 10/04/2023] Open
Abstract
IQSEC2 (aka BRAG1) is a guanine nucleotide exchange factor (GEF) highly enriched in synapses. As a top neurodevelopmental disorder risk gene, numerous mutations are identified in Iqsec2 in patients with intellectual disabilities accompanied by other developmental, neurological, and psychiatric symptoms, though with poorly understood underlying molecular mechanisms. The atomic structures of IQSECs, together with biochemical analysis, presented in this study reveal an autoinhibition and Ca2+-dependent allosteric activation mechanism for all IQSECs and rationalize how each identified Iqsec2 mutation can alter the structure and function of the enzyme. Transgenic mice modeling two pathogenic variants of Iqsec2 (R359C and Q801P), with one activating and the other inhibiting the GEF activity of the enzyme, recapitulate distinct clinical phenotypes in patients. Our study demonstrates that different mutations on one gene such as Iqsec2 can have distinct neurological phenotypes and accordingly will require different therapeutic strategies.
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Affiliation(s)
- Guanhua Bai
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
| | - Hao Li
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Pengwei Qin
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Yiqing Guo
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Wanfa Yang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
| | - Yinmiao Lian
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Fei Ye
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
| | - Jianxin Chen
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Meiling Wu
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Ruifeng Huang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
| | - Jinsong Li
- State Key Laboratory of Cell Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China
- School of Life Science and Technology, Shanghai Tech University, Shanghai, China
| | - Youming Lu
- Department of Pathophysiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Institute for Brain Research, Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan, China
| | - Mingjie Zhang
- School of Life Sciences, Southern University of Science and Technology, Shenzhen, China
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, China
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen, China
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Brown JC, Hell JW, Gerges NZ. BRAG about (s)lots. J Cell Biol 2023; 222:e202310023. [PMID: 37938213 PMCID: PMC10631466 DOI: 10.1083/jcb.202310023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023] Open
Abstract
Mutations in IQSEC2/BRAG1 cause intellectual dysfunction by impairing ARF-GEF activity and long-term depression. In this issue, Bai et al. (https://doi.org/10.1083/jcb.202307117) discover how constitutive ARF-GEF activity is regulated by a closed conformation which opens in the presence of Ca2+. Two known pathogenic mutations cause "leaky" autoinhibition with reduced synaptic dynamic range and impaired cognitive performance.
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Affiliation(s)
- Joshua C. Brown
- Division of Depression and Anxiety Disorders, Brain Stimulation Mechanisms Laboratory, McLean Hospital, Belmont, MA, USA
- Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Johannes W. Hell
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Nashaat Z. Gerges
- Biopharmaceutical Sciences Department, School of Pharmacy, Medical College of Wisconsin, Milwaukee, WI, USA
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5
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Molecular Insights into IQSEC2 Disease. Int J Mol Sci 2023; 24:ijms24054984. [PMID: 36902414 PMCID: PMC10003148 DOI: 10.3390/ijms24054984] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/02/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Recent insights into IQSEC2 disease are summarized in this review as follows: (1) Exome sequencing of IQSEC2 patient DNA has led to the identification of numerous missense mutations that delineate at least six and possibly seven essential functional domains present in the IQSEC2 gene. (2) Experiments using IQSEC2 transgenic and knockout (KO) mouse models have recapitulated the presence of autistic-like behavior and epileptic seizures in affected animals; however, seizure severity and etiology appear to vary considerably between models. (3) Studies in IQSEC2 KO mice reveal that IQSEC2 is involved in inhibitory as well as stimulatory neurotransmission. The overall picture appears to be that mutated or absent IQSEC2 arrests neuronal development, resulting in immature neuronal networks. Subsequent maturation is aberrant, leading to increased inhibition and reduced neuronal transmission. (4) The levels of Arf6-GTP remain constitutively high in IQSEC2 knockout mice despite the absence of IQSEC2 protein, indicating impaired regulation of the Arf6 guanine nucleotide exchange cycle. (5) A new therapy that has been shown to reduce the seizure burden for the IQSEC2 A350V mutation is heat treatment. Induction of the heat shock response may be responsible for this therapeutic effect.
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Daily Brief Heat Therapy Reduces Seizures in A350V IQSEC2 Mice and Is Associated with Correction of AMPA Receptor-Mediated Synaptic Dysfunction. Int J Mol Sci 2023; 24:ijms24043924. [PMID: 36835332 PMCID: PMC9965438 DOI: 10.3390/ijms24043924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 02/12/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Purposeful induction of fever for healing, including the treatment of epilepsy, was used over 2000 years ago by Hippocrates. More recently, fever has been demonstrated to rescue behavioral abnormalities in children with autism. However, the mechanism of fever benefit has remained elusive due in large part to the lack of appropriate human disease models recapitulating the fever effect. Pathological mutations in the IQSEC2 gene are frequently seen in children presenting with intellectual disability, autism and epilepsy. We recently described a murine A350V IQSEC2 disease model, which recapitulates important aspects of the human A350V IQSEC2 disease phenotype and the favorable response to a prolonged and sustained rise in body core temperature in a child with the mutation. Our goal has been to use this system to understand the mechanism of fever benefit and then develop drugs that can mimic this effect and reduce IQSEC2-associated morbidity. In this study, we first demonstrate a reduction in seizures in the mouse model following brief periods of heat therapy, similar to what was observed in a child with the mutation. We then show that brief heat therapy is associated with the correction of synaptic dysfunction in neuronal cultures of A350V mice, likely mediated by Arf6-GTP.
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7
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Brown JC, Higgins ES, George MS. Synaptic Plasticity 101: The Story of the AMPA Receptor for the Brain Stimulation Practitioner. Neuromodulation 2022; 25:1289-1298. [PMID: 35088731 PMCID: PMC10479373 DOI: 10.1016/j.neurom.2021.09.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/10/2021] [Accepted: 09/08/2021] [Indexed: 02/04/2023]
Abstract
The fields of Neurobiology and Neuromodulation have never been closer. Consequently, the phrase "synaptic plasticity" has become very familiar to non-basic scientists, without actually being very familiar. We present the "Story of the AMPA receptor," an easy-to-understand "10,000 ft" narrative overview of synaptic plasticity, oriented toward the brain stimulation clinician or scientist without basic science training. Neuromodulation is unparalleled in its capacity to both modulate and probe plasticity, yet many are not comfortable with their grasp of the topic. Here, we describe the seminal discoveries that defined the canonical mechanisms of long-term potentiation (LTP), long-term depression (LTD), and homeostatic plasticity. We then provide a conceptual framework for how plasticity at the synapse is accomplished, describing the functional roles of N-methyl-d-aspartate (NMDA) receptors and calcium, their effect on calmodulin, phosphatases (ie, calcineurin), kinases (ie, calcium/calmodulin-dependent protein kinase [CaMKII]), and structural "scaffolding" proteins (ie, post-synaptic density protein [PSD-95]). Ultimately, we describe how these affect the α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor. More specifically, AMPA receptor delivery to (LTP induction), removal from (LTD), or recycling within (LTP maintenance) the synapse is determined by the status of phosphorylation and protein binding at specific sites on the tails of AMPA receptor subunits: GluA1 and GluA2. Finally, we relate these to transcranial magnetic stimulation (TMS) treatment, highlighting evidences for LTP as the basis of high-frequency TMS therapy, and briefly touch on the role of plasticity for other brain stimulation modalities. In summary, we present Synaptic Plasticity 101 as a singular introductory reference for those less familiar with the mechanisms of synaptic plasticity.
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Affiliation(s)
- Joshua C Brown
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA; Department of Neurology, Medical University of South Carolina, Charleston, SC, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA.
| | - Edmund S Higgins
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Mark S George
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA; Ralph Johnson VA Medical Center, Charleston, SC, USA
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8
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Ito A, Fukaya M, Okamoto H, Sakagami H. Physiological and Pathological Roles of the Cytohesin Family in Neurons. Int J Mol Sci 2022; 23:5087. [PMID: 35563476 PMCID: PMC9104363 DOI: 10.3390/ijms23095087] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/01/2022] [Accepted: 05/02/2022] [Indexed: 02/05/2023] Open
Abstract
The cytohesin proteins, consisting of four closely related members (cytohesins-1, -2, -3, and -4), are a subfamily of the Sec7 domain-containing guanine nucleotide exchange factors for ADP ribosylation factors (Arfs), which are critical regulators of membrane trafficking and actin cytoskeleton remodeling. Recent advances in molecular biological techniques and the development of a specific pharmacological inhibitor for cytohesins, SecinH3, have revealed the functional involvement of the cytohesin-Arf pathway in diverse neuronal functions from the formation of axons and dendrites, axonal pathfinding, and synaptic vesicle recycling, to pathophysiological processes including chronic pain and neurotoxicity induced by proteins related to neurodegenerative disorders, such as amyotrophic lateral sclerosis and Alzheimer's disease. Here, we review the physiological and pathological roles of the cytohesin-Arf pathway in neurons and discuss the future directions of this research field.
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Affiliation(s)
- Akiko Ito
- Department of Anesthesiology, Kitasato University School of Medicine, Sagamihara 252-0374, Kanagawa, Japan; (A.I.); (H.O.)
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara 252-0374, Kanagawa, Japan;
| | - Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara 252-0374, Kanagawa, Japan;
| | - Hirotsugu Okamoto
- Department of Anesthesiology, Kitasato University School of Medicine, Sagamihara 252-0374, Kanagawa, Japan; (A.I.); (H.O.)
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara 252-0374, Kanagawa, Japan;
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Kim D, Jung H, Shirai Y, Kim H, Kim J, Lim D, Mori T, Lee H, Park D, Kim HY, Guo Q, Pang B, Qiu W, Cao X, Kouyama-Suzuki E, Uemura T, Kasem E, Fu Y, Kim S, Tokunaga A, Yoshizawa T, Suzuki T, Sakagami H, Lee KJ, Ko J, Tabuchi K, Um JW. IQSEC3 Deletion Impairs Fear Memory Through Upregulation of Ribosomal S6K1 Signaling in the Hippocampus. Biol Psychiatry 2022; 91:821-831. [PMID: 35219498 DOI: 10.1016/j.biopsych.2021.12.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 11/29/2021] [Accepted: 12/15/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND IQSEC3, a gephyrin-binding GABAergic (gamma-aminobutyric acidergic) synapse-specific guanine nucleotide exchange factor, was recently reported to regulate activity-dependent GABAergic synapse maturation, but the underlying signaling mechanisms remain incompletely understood. METHODS We generated mice with conditional knockout (cKO) of Iqsec3 to examine whether altered synaptic inhibition influences hippocampus-dependent fear memory formation. In addition, electrophysiological recordings, immunohistochemistry, and behavioral assays were used to address our question. RESULTS We found that Iqsec3-cKO induces a specific reduction in GABAergic synapse density, GABAergic synaptic transmission, and maintenance of long-term potentiation in the hippocampal CA1 region. In addition, Iqsec3-cKO mice exhibited impaired fear memory formation. Strikingly, Iqsec3-cKO caused abnormally enhanced activation of ribosomal P70-S6K1-mediated signaling in the hippocampus but not in the cortex. Furthermore, inhibiting upregulated S6K1 signaling by expressing dominant-negative S6K1 in the hippocampal CA1 of Iqsec3-cKO mice completely rescued impaired fear learning and inhibitory synapse density but not deficits in long-term potentiation maintenance. Finally, upregulated S6K1 signaling was rescued by IQSEC3 wild-type, but not by an ARF-GEF (adenosine diphosphate ribosylation factor-guanine nucleotide exchange factor) inactive IQSEC3 mutant. CONCLUSIONS Our results suggest that IQSEC3-mediated balanced synaptic inhibition in hippocampal CA1 is critical for the proper formation of hippocampus-dependent fear memory.
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Affiliation(s)
- Dongwook Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Yoshinori Shirai
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Jinhu Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Dongseok Lim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Takuma Mori
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan; Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano, Japan
| | - Hyojeong Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Dongseok Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Hee Young Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Qi Guo
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Bo Pang
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Wen Qiu
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Xueshan Cao
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Emi Kouyama-Suzuki
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Takeshi Uemura
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Enas Kasem
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan; Department of Zoology, Faculty of Science, Kafrelsheikh University, Kafr el-Sheikh, Egypt
| | - Yu Fu
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Seungjoon Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Akinori Tokunaga
- Division of Laboratory Animal Resources, Life Science Research Laboratory, University of Fukui, Fukui, Japan
| | - Takahiro Yoshizawa
- Research Center for Supports to Advanced Science, Shinshu University, Nagano, Japan
| | - Tatsuo Suzuki
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Kanagawa, Japan
| | - Kea Joo Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea; Neural Circuits Research Group, Korea Brain Research Institute, Daegu, South Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
| | - Katsuhiko Tabuchi
- Department of Molecular and Cellular Physiology, Institute of Medicine, Academic Assembly, Shinshu University, Nagano, Japan; Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano, Japan.
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea.
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Hoerndli FJ, Brockie PJ, Wang R, Mellem JE, Kallarackal A, Doser RL, Pierce DM, Madsen DM, Maricq AV. MAPK signaling and a mobile scaffold complex regulate AMPA receptor transport to modulate synaptic strength. Cell Rep 2022; 38:110577. [PMID: 35354038 PMCID: PMC9965202 DOI: 10.1016/j.celrep.2022.110577] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 01/31/2022] [Accepted: 03/04/2022] [Indexed: 12/27/2022] Open
Abstract
Synaptic plasticity depends on rapid experience-dependent changes in the number of neurotransmitter receptors. Previously, we demonstrated that motor-mediated transport of AMPA receptors (AMPARs) to and from synapses is a critical determinant of synaptic strength. Here, we describe two convergent signaling pathways that coordinate the loading of synaptic AMPARs onto scaffolds, and scaffolds onto motors, thus providing a mechanism for experience-dependent changes in synaptic strength. We find that an evolutionarily conserved JIP-protein scaffold complex and two classes of mitogen-activated protein kinase (MAPK) proteins mediate AMPAR transport by kinesin-1 motors. Genetic analysis combined with in vivo, real-time imaging in Caenorhabditis elegans revealed that CaMKII is required for loading AMPARs onto the scaffold, and MAPK signaling is required for loading the scaffold complex onto motors. Our data support a model where CaMKII signaling and a MAPK-signaling pathway cooperate to facilitate the rapid exchange of AMPARs required for early stages of synaptic plasticity.
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Affiliation(s)
- Frédéric J. Hoerndli
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA,Correspondence: (F.J.H.), (A.V.M.)
| | - Penelope J. Brockie
- Department of Neurobiology, University of Utah, Salt Lake City, UT 84112-9458, USA
| | - Rui Wang
- Pathology Department, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Jerry E. Mellem
- Department of Neurobiology, University of Utah, Salt Lake City, UT 84112-9458, USA
| | - Angy Kallarackal
- Department of Psychology, Mount Saint Mary’s University, Emmitsburg, MD 21727, USA
| | - Rachel L. Doser
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Dayton M. Pierce
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - David M. Madsen
- Department of Neurobiology, University of Utah, Salt Lake City, UT 84112-9458, USA
| | - Andres V. Maricq
- Department of Neurobiology, University of Utah, Salt Lake City, UT 84112-9458, USA,Lead contact,Correspondence: (F.J.H.), (A.V.M.)
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11
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Kane O, McCoy A, Jada R, Borisov V, Zag L, Zag A, Schragenheim-Rozales K, Shalgi R, Levy NS, Levy AP, Marsh ED. Characterization of spontaneous seizures and EEG abnormalities in a mouse model of the human A350V IQSEC2 mutation and identification of a possible target for precision medicine based therapy. Epilepsy Res 2022; 182:106907. [DOI: 10.1016/j.eplepsyres.2022.106907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 02/01/2022] [Accepted: 03/11/2022] [Indexed: 11/16/2022]
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12
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Niescier RF, Lin YC. The Potential Role of AMPA Receptor Trafficking in Autism and Other Neurodevelopmental Conditions. Neuroscience 2021; 479:180-191. [PMID: 34571086 DOI: 10.1016/j.neuroscience.2021.09.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 09/06/2021] [Accepted: 09/15/2021] [Indexed: 12/21/2022]
Abstract
Autism Spectrum Disorder (ASD) is a multifaceted condition associated with difficulties in social interaction and communication. It also shares several comorbidities with other neurodevelopmental conditions. Intensive research examining the molecular basis and characteristics of ASD has revealed an association with a large number and variety of low-penetrance genes. Many of the variants associated with ASD are in genes underlying pathways involved in long-term potentiation (LTP) or depression (LTD). These mechanisms then control the tuning of neuronal connections in response to experience by modifying and trafficking ionotropic glutamate receptors at the post-synaptic areas. Despite the high genetic heterogeneity in ASD, surface trafficking of the α-amino-3-hydroxy-5-Methyl-4-isoxazolepropionate (AMPA) receptor is a vulnerable pathway in ASD. In this review, we discuss autism-related alterations in the trafficking of AMPA receptors, whose surface density and composition at the post-synapse determine the strength of the excitatory connection between neurons. We highlight genes associated with neurodevelopmental conditions that share the autism comorbidity, including Fragile X syndrome, Rett Syndrome, and Tuberous Sclerosis, as well as the autism-risk genes NLGNs, IQSEC2, DOCK4, and STXBP5, all of which are involved in regulating AMPAR trafficking to the post-synaptic surface.
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Affiliation(s)
- Robert F Niescier
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA.
| | - Yu-Chih Lin
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA.
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13
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Mehta A, Shirai Y, Kouyama-Suzuki E, Zhou M, Yoshizawa T, Yanagawa T, Mori T, Tabuchi K. IQSEC2 Deficiency Results in Abnormal Social Behaviors Relevant to Autism by Affecting Functions of Neural Circuits in the Medial Prefrontal Cortex. Cells 2021; 10:2724. [PMID: 34685703 PMCID: PMC8534507 DOI: 10.3390/cells10102724] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 12/28/2022] Open
Abstract
IQSEC2 is a guanine nucleotide exchange factor (GEF) for ADP-ribosylation factor 6 (Arf6), of which protein is exclusively localized to the postsynaptic density of the excitatory synapse. Human genome studies have revealed that the IQSEC2 gene is associated with X-linked neurodevelopmental disorders, such as intellectual disability (ID), epilepsy, and autism. In this study, we examined the behavior and synapse function in IQSEC2 knockout (KO) mice that we generated using CRIPSR/Cas9-mediated genome editing to solve the relevance between IQSEC2 deficiency and the pathophysiology of neurodevelopmental disorders. IQSEC2 KO mice exhibited autistic behaviors, such as overgrooming and social deficits. We identified that up-regulation of c-Fos expression in the medial prefrontal cortex (mPFC) induced by social stimulation was significantly attenuated in IQSEC2 KO mice. Whole cell electrophysiological recording identified that synaptic transmissions mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), N-methyl-D-aspartate receptor (NMDAR), and γ-aminobutyric acid receptor (GABAR) were significantly decreased in pyramidal neurons in layer 5 of the mPFC in IQSEC2 KO mice. Reexpression of IQSEC2 isoform 1 in the mPFC of IQSEC2 KO mice using adeno-associated virus (AAV) rescued both synaptic and social deficits, suggesting that impaired synaptic function in the mPFC is responsible for social deficits in IQSEC2 KO mice.
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Affiliation(s)
- Anuradha Mehta
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Yoshinori Shirai
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Emi Kouyama-Suzuki
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Mengyun Zhou
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
| | - Takahiro Yoshizawa
- Research Center for Advanced Science and Technology, Shinshu University, Matsumoto 390-8621, Japan;
| | - Toru Yanagawa
- Department of Oral and Maxillofacial Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan;
| | - Takuma Mori
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
- Department of NeuroHealth Innovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan
| | - Katsuhiko Tabuchi
- Department of Molecular and Cellular Physiology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan; (A.M.); (Y.S.); (E.K.-S.); (M.Z.); (T.M.)
- Department of NeuroHealth Innovation, Institute for Biomedical Sciences, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Matsumoto 390-8621, Japan
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14
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Jabarin R, Levy N, Abergel Y, Berman JH, Zag A, Netser S, Levy AP, Wagner S. Pharmacological modulation of AMPA receptors rescues specific impairments in social behavior associated with the A350V Iqsec2 mutation. Transl Psychiatry 2021; 11:234. [PMID: 33888678 PMCID: PMC8062516 DOI: 10.1038/s41398-021-01347-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 12/18/2022] Open
Abstract
In this study we tested the hypothesis that pharmacological modulation of glutamatergic neurotransmission could rescue behavioral deficits exhibited by mice carrying a specific mutation in the Iqsec2 gene. The IQSEC2 protein plays a key role in glutamatergic synapses and mutations in the IQSEC2 gene are a frequent cause of neurodevelopmental disorders. We have recently reported on the molecular pathophysiology of one such mutation A350V and demonstrated that this mutation downregulates AMPA type glutamatergic receptors (AMPAR) in A350V mice. Here we sought to identify behavioral deficits in A350V mice and hypothesized that we could rescue these deficits by PF-4778574, a positive AMPAR modulator. Using a battery of social behavioral tasks, we found that A350V Iqsec2 mice exhibit specific deficits in sex preference and emotional state preference behaviors as well as in vocalizations when encountering a female mouse. The social discrimination deficits, but not the impaired vocalization, were rescued with a single dose of PF-4778574. We conclude that social behavior deficits associated with the A350V Iqsec2 mutation may be rescued by enhancing AMPAR mediated synaptic transmission.
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Affiliation(s)
- Renad Jabarin
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Nina Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yasmin Abergel
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Joshua H Berman
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Amir Zag
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Shai Netser
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
| | - Shlomo Wagner
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa, Israel.
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15
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Lichtman D, Bergmann E, Kavushansky A, Cohen N, Levy NS, Levy AP, Kahn I. Structural and functional brain-wide alterations in A350V Iqsec2 mutant mice displaying autistic-like behavior. Transl Psychiatry 2021; 11:181. [PMID: 33753721 PMCID: PMC7985214 DOI: 10.1038/s41398-021-01289-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 02/15/2021] [Accepted: 02/24/2021] [Indexed: 12/21/2022] Open
Abstract
IQSEC2 is an X-linked gene that is associated with autism spectrum disorder (ASD), intellectual disability, and epilepsy. IQSEC2 is a postsynaptic density protein, localized on excitatory synapses as part of the NMDA receptor complex and is suggested to play a role in AMPA receptor trafficking and mediation of long-term depression. Here, we present brain-wide structural volumetric and functional connectivity characterization in a novel mouse model with a missense mutation in the IQ domain of IQSEC2 (A350V). Using high-resolution structural and functional MRI, we show that animals with the A350V mutation display increased whole-brain volume which was further found to be specific to the cerebral cortex and hippocampus. Moreover, using a data-driven approach we identify putative alterations in structure-function relations of the frontal, auditory, and visual networks in A350V mice. Examination of these alterations revealed an increase in functional connectivity between the anterior cingulate cortex and the dorsomedial striatum. We also show that corticostriatal functional connectivity is correlated with individual variability in social behavior only in A350V mice, as assessed using the three-chamber social preference test. Our results at the systems-level bridge the impact of previously reported changes in AMPA receptor trafficking to network-level disruption and impaired social behavior. Further, the A350V mouse model recapitulates similarly reported brain-wide changes in other ASD mouse models, with substantially different cellular-level pathologies that nonetheless result in similar brain-wide alterations, suggesting that novel therapeutic approaches in ASD that result in systems-level rescue will be relevant to IQSEC2 mutations.
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Affiliation(s)
- Daniela Lichtman
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel
| | - Eyal Bergmann
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel
| | - Alexandra Kavushansky
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel
| | - Nadav Cohen
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel
| | - Nina S Levy
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel
| | - Andrew P Levy
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel.
| | - Itamar Kahn
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, 31096, Israel.
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16
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Briševac D, Scholz R, Du D, Elagabani MN, Köhr G, Kornau HC. The small GTPase Arf6 is dysregulated in a mouse model for fragile X syndrome. J Neurochem 2020; 157:666-683. [PMID: 33125726 DOI: 10.1111/jnc.15230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 10/09/2020] [Accepted: 10/27/2020] [Indexed: 11/29/2022]
Abstract
Fragile X syndrome (FXS), the most common inherited cause of intellectual disability, results from silencing of the fragile X mental retardation gene 1 (FMR1). The analyses of FXS patients' brain autopsies revealed an increased density of immature dendritic spines in cortical areas. We hypothesize that the small GTPase Arf6, an actin regulator critical for the development of glutamatergic synapses and dendritic spines, is implicated in FXS. Here, we determined the fraction of active, GTP-bound Arf6 in cortical neuron cultures and synaptoneurosomes from Fmr1 knockout mice, measured actin polymerization in neurons expressing Arf6 mutants with variant GTP- or GDP-binding properties, and recorded hippocampal long-term depression induced by metabotropic glutamate receptors (mGluR-LTD) in acute brain slices. We detected a persistently elevated Arf6 activity, a loss of Arf6 sensitivity to synaptic stimulation and an increased Arf6-dependent dendritic actin polymerization in mature Fmr1 knockout neurons. Similar imbalances in Arf6-GTP levels and actin filament assembly were caused in wild-type neurons by RNAi-mediated depletion of the postsynaptic Arf6 guanylate exchange factors IQSEC1 (BRAG2) or IQSEC2 (BRAG1). Targeted deletion of Iqsec1 in hippocampal neurons of 3-week-old mice interfered with mGluR-LTD in wild-type, but not in Fmr1 knockout mice. Collectively, these data suggest an aberrant Arf6 regulation in Fmr1 knockout neurons with consequences for the actin cytoskeleton, spine morphology, and synaptic plasticity. Moreover, FXS and syndromes caused by genetic variants in IQSEC1 and IQSEC2 share intellectual disabilities and developmental delay as main symptoms. Therefore, dysregulation of Arf6 may contribute to the cognitive impairment in FXS.
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Affiliation(s)
- Dušica Briševac
- Neuroscience Research Center (NWFZ), Charité - Universitätsmedizin Berlin, Berlin, Germany.,Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Ralf Scholz
- Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Dan Du
- Central Institute of Mental Health, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | | | - Georg Köhr
- Central Institute of Mental Health, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.,Department of Neurophysiology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Hans-Christian Kornau
- Neuroscience Research Center (NWFZ), Charité - Universitätsmedizin Berlin, Berlin, Germany.,Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany
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17
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Rozés-Salvador V, González-Billault C, Conde C. The Recycling Endosome in Nerve Cell Development: One Rab to Rule Them All? Front Cell Dev Biol 2020; 8:603794. [PMID: 33425908 PMCID: PMC7793921 DOI: 10.3389/fcell.2020.603794] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 11/11/2020] [Indexed: 12/13/2022] Open
Abstract
Endocytic recycling is an intracellular process that returns internalized molecules back to the plasma membrane and plays crucial roles not only in the reuse of receptor molecules but also in the remodeling of the different components of this membrane. This process is required for a diversity of cellular events, including neuronal morphology acquisition and functional regulation, among others. The recycling endosome (RE) is a key vesicular component involved in endocytic recycling. Recycling back to the cell surface may occur with the participation of several different Rab proteins, which are master regulators of membrane/protein trafficking in nerve cells. The RE consists of a network of interconnected and functionally distinct tubular subdomains that originate from sorting endosomes and transport their cargoes along microtubule tracks, by fast or slow recycling pathways. Different populations of REs, particularly those formed by Rab11, Rab35, and Arf6, are associated with a myriad of signaling proteins. In this review, we discuss the cumulative evidence suggesting the existence of heterogeneous domains of REs, controlling different aspects of neurogenesis, with a particular focus on the commonalities and singularities of these REs and their contribution to nerve development and differentiation in several animal models.
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Affiliation(s)
- Victoria Rozés-Salvador
- Instituto de Investigación Médica Mercedes y Martín Ferreyra INIMEC-CONICET-UNC, Córdoba, Argentina.,Instituto de Ciencias Básicas, Universidad Nacional de Villa María, Córdoba, Argentina
| | - Christian González-Billault
- Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.,Department of Neurosciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Geroscience Center for Brain Health and Metabolism, Santiago, Chile.,The Buck Institute for Research on Aging, Novato, CA, United States
| | - Cecilia Conde
- Instituto de Investigación Médica Mercedes y Martín Ferreyra INIMEC-CONICET-UNC, Córdoba, Argentina
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18
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RAGE signaling is required for AMPA receptor dysfunction in the hippocampus of hyperglycemic mice. Physiol Behav 2020; 229:113255. [PMID: 33221393 DOI: 10.1016/j.physbeh.2020.113255] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 10/31/2020] [Accepted: 11/18/2020] [Indexed: 01/08/2023]
Abstract
Diabetes in humans has been associated for a long time with cognitive dysfunction. In rodent animal models, cognitive dysfunction can manifest as impaired hippocampal synaptic plasticity. Particular attention has been concentrated on the receptor for advanced glycation end products (RAGE), which is implicated in multiple diabetic complications involving the development of vascular and peripheral nerve abnormalities. In this study, we hypothesize that RAGE signaling alters glutamate receptor function and expression, impairing synaptic transmission in the hippocampus. Using preparations of hippocampal slices from male mice, we show a RAGE-dependent decrease in long-term potentiation (LTP) and an increase in paired-pulse facilitation (PPF) following streptozotocin (STZ)-induced diabetes. Consistently, in hippocampal cultures from male and female neonatal mice, high glucose caused a RAGE-dependent reduction of AMPA- but not NMDA-evoked currents, and an increase in cytosolic reactive oxygen species (ROS). Consistently, when cultures were co-treated with high glucose and the RAGE antagonist FPS-ZM1, AMPA-evoked currents were unchanged. Hippocampi from STZ-induced hyperglycemic wild type (WT) mice showed increased RAGE expression concomitant with a decrease of both expression and phosphorylation (Ser 831 and 845) of the AMPA GluA1 subunit. We found these changes correlated to activation of the MAPK pathway, consistent with decreased pJNK/JNK ratio and the JNK kinase, pMEK7. As no changes in expression or phosphorylation of regulatory proteins were observed in hippocampi from STZ-induced hyperglycemic RAGE-KO mice, we report a RAGE-dependent impairment in the hippocampi of hyperglycemic WT mice, with reduced AMPA receptor expression/function and LTP deficits.
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19
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Warnet XL, Bakke Krog H, Sevillano-Quispe OG, Poulsen H, Kjaergaard M. The C-terminal domains of the NMDA receptor: How intrinsically disordered tails affect signalling, plasticity and disease. Eur J Neurosci 2020; 54:6713-6739. [PMID: 32464691 DOI: 10.1111/ejn.14842] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/16/2020] [Accepted: 05/18/2020] [Indexed: 01/14/2023]
Abstract
NMDA receptors are part of the ionotropic glutamate receptor family, and are crucial for neurotransmission and memory. At the cellular level, the effects of activating these receptors include long-term potentiation (LTP) or depression (LTD). The NMDA receptor is a stringently gated cation channel permeable to Ca2+ , and it shares the molecular architecture of a tetrameric ligand-gated ion channel with the other family members. Its subunits, however, have uniquely long cytoplasmic C-terminal domains (CTDs). While the molecular gymnastics of the extracellular domains have been described in exquisite detail, much less is known about the structure and function of these CTDs. The CTDs vary dramatically in length and sequence between receptor subunits, but they all have a composition characteristic of intrinsically disordered proteins. The CTDs affect channel properties, trafficking and downstream signalling output from the receptor, and these functions are regulated by alternative splicing, protein-protein interactions, and post-translational modifications such as phosphorylation and palmitoylation. Here, we review the roles of the CTDs in synaptic plasticity with a focus on biochemical mechanisms. In total, the CTDs play a multifaceted role as a modifier of channel function, a regulator of cellular location and abundance, and signalling scaffold control the downstream signalling output.
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Affiliation(s)
- Xavier L Warnet
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Helle Bakke Krog
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Oscar G Sevillano-Quispe
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Hanne Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
| | - Magnus Kjaergaard
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,The Danish Research Institute for Translational Neuroscience (DANDRITE), Aarhus University, Aarhus, Denmark.,The Center for Proteins in Memory (PROMEMO), Aarhus University, Aarhus, Denmark
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20
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Mesman S, Bakker R, Smidt MP. Tcf4 is required for correct brain development during embryogenesis. Mol Cell Neurosci 2020; 106:103502. [PMID: 32474139 DOI: 10.1016/j.mcn.2020.103502] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 04/28/2020] [Accepted: 05/19/2020] [Indexed: 01/02/2023] Open
Abstract
Tcf4 has been linked to autism, schizophrenia, and Pitt-Hopkins Syndrome (PTHS) in humans, suggesting a role for Tcf4 in brain development and importantly cortical development. However, the mechanisms behind its role in disease and brain development are still elusive. We provide evidence that Tcf4 has a critical function in the differentiation of cortical regions, corpus callosum and anterior commissure formation, and development of the hippocampus during murine embryonic development. In the present study, we show that Tcf4 is expressed throughout the developing brain at the peak of neurogenesis. Deletion of Tcf4 results in mis-specification of the cortical neurons, malformation of the corpus callosum and anterior commissure, and hypoplasia of the hippocampus. Furthermore, the Tcf4 mutant shows an absence of midline remodeling, underlined by the loss of GFAP-expressing midline glia in the indusium griseum and callosal wedge and midline zipper glia in the telencephalic midline. RNA-sequencing on E14.5 cortex material shows that Tcf4 functions as a transcriptional activator and loss of Tcf4 results in downregulation of genes linked to neurogenesis and neuronal maturation. Furthermore, many genes that are differentially expressed after Tcf4 ablation are linked to other neurodevelopmental disorders. Taken together, we show that correct brain development and neuronal differentiation are severely affected in Tcf4 mutants, phenocopying morphological brain defects detected in PTHS patients. The presented data identifies new leads to understand the mechanisms behind brain and specifically cortical development and can provide novel insights in developmental mechanisms underlying human brain defects.
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Affiliation(s)
- Simone Mesman
- Swammerdam Institute for Life Sciences, FNWI University of Amsterdam, Science Park 904, 1098XH Amsterdam, the Netherlands
| | - Reinier Bakker
- Swammerdam Institute for Life Sciences, FNWI University of Amsterdam, Science Park 904, 1098XH Amsterdam, the Netherlands
| | - Marten P Smidt
- Swammerdam Institute for Life Sciences, FNWI University of Amsterdam, Science Park 904, 1098XH Amsterdam, the Netherlands.
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21
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D'Souza RS, Lim JY, Turgut A, Servage K, Zhang J, Orth K, Sosale NG, Lazzara MJ, Allegood J, Casanova JE. Calcium-stimulated disassembly of focal adhesions mediated by an ORP3/IQSec1 complex. eLife 2020; 9:54113. [PMID: 32234213 PMCID: PMC7159923 DOI: 10.7554/elife.54113] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/30/2020] [Indexed: 12/15/2022] Open
Abstract
Coordinated assembly and disassembly of integrin-mediated focal adhesions (FAs) is essential for cell migration. Many studies have shown that FA disassembly requires Ca2+ influx, however our understanding of this process remains incomplete. Here, we show that Ca2+ influx via STIM1/Orai1 calcium channels, which cluster near FAs, leads to activation of the GTPase Arf5 via the Ca2+-activated GEF IQSec1, and that both IQSec1 and Arf5 activation are essential for adhesion disassembly. We further show that IQSec1 forms a complex with the lipid transfer protein ORP3, and that Ca2+ influx triggers PKC-dependent translocation of this complex to ER/plasma membrane (PM) contact sites adjacent to FAs. In addition to allosterically activating IQSec1, ORP3 also extracts PI4P from the PM, in exchange for phosphatidylcholine. ORP3-mediated lipid exchange is also important for FA turnover. Together, these findings identify a new pathway that links calcium influx to FA turnover during cell migration.
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Affiliation(s)
- Ryan S D'Souza
- Department of Cell Biology, University of Virginia Health System, Charlottesville, United States
| | - Jun Y Lim
- Department of Cell Biology, University of Virginia Health System, Charlottesville, United States
| | - Alper Turgut
- Department of Cell Biology, University of Virginia Health System, Charlottesville, United States
| | - Kelly Servage
- Department of Molecular Biology, University of Texas Southwest Medical Center, Dallas, United States.,Howard Hughes Medical Institute, Dallas, United States
| | - Junmei Zhang
- Department of Cell Biology, University of Virginia Health System, Charlottesville, United States
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwest Medical Center, Dallas, United States.,Howard Hughes Medical Institute, Dallas, United States
| | - Nisha G Sosale
- Department of Chemical Engineering, University of Virginia, Charlottesville, United States
| | - Matthew J Lazzara
- Department of Chemical Engineering, University of Virginia, Charlottesville, United States
| | - Jeremy Allegood
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, United States
| | - James E Casanova
- Department of Cell Biology, University of Virginia Health System, Charlottesville, United States
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22
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Optogenetic Control of Spine-Head JNK Reveals a Role in Dendritic Spine Regression. eNeuro 2020; 7:ENEURO.0303-19.2019. [PMID: 31937523 PMCID: PMC7053173 DOI: 10.1523/eneuro.0303-19.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 12/27/2022] Open
Abstract
In this study, we use an optogenetic inhibitor of c-Jun NH2-terminal kinase (JNK) in dendritic spine sub-compartments of rat hippocampal neurons. We show that JNK inhibition exerts rapid (within seconds) reorganization of actin in the spine-head. Using real-time Förster resonance energy transfer (FRET) to measure JNK activity, we find that either excitotoxic insult (NMDA) or endocrine stress (corticosterone), activate spine-head JNK causing internalization of AMPARs and spine retraction. Both events are prevented upon optogenetic inhibition of JNK, and rescued by JNK inhibition even 2 h after insult. Moreover, we identify that the fast-acting anti-depressant ketamine reduces JNK activity in hippocampal neurons suggesting that JNK inhibition may be a downstream mediator of its anti-depressant effect. In conclusion, we show that JNK activation plays a role in triggering spine elimination by NMDA or corticosterone stress, whereas inhibition of JNK facilitates regrowth of spines even in the continued presence of glucocorticoid. This identifies that JNK acts locally in the spine-head to promote AMPAR internalization and spine shrinkage following stress, and reveals a protective function for JNK inhibition in preventing spine regression.
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Altered excitatory transmission onto hippocampal interneurons in the IQSEC2 mouse model of X-linked neurodevelopmental disease. Neurobiol Dis 2020; 137:104758. [PMID: 31978606 DOI: 10.1016/j.nbd.2020.104758] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2019] [Revised: 12/16/2019] [Accepted: 01/20/2020] [Indexed: 02/01/2023] Open
Abstract
Mutations in the X-linked gene IQSEC2 are associated with multiple cases of epilepsy, epileptic encephalopathy, intellectual disability and autism spectrum disorder, the mechanistic understanding and successful treatment of which remain a significant challenge in IQSEC2 and related neurodevelopmental genetic diseases. To investigate disease etiology, we studied behaviors and synaptic function in IQSEC2 deficient mice. Hemizygous Iqsec2 null males exhibit growth deficits, hyperambulation and hyperanxiety phenotypes. Adult hemizygotes experience lethal spontaneous seizures, but paradoxically have a significantly increased threshold to electrically induced limbic seizures and relative resistance to chemically induced seizures. Although there are no gross defects in brain morphology, hemizygotes exhibit stark hippocampal reactive astrogliosis. Electrophysiological recordings of hippocampal neurons reveal increased excitatory drive specifically onto interneurons, and significant alterations in intrinsic electrical properties specific to the interneuron population. As they age, hemizygotes also develop an increased abundance of parvalbumin-positive interneurons in the hippocampus, neurons in which IQSEC2 is expressed in addition to the excitatory neurons. These findings point to a novel role of IQSEC2 in hippocampal interneuron synaptic function and development with implications for a class of intractable neurodevelopmental diseases.
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24
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Kim H, Jung H, Jung H, Kwon SK, Ko J, Um JW. The small GTPase ARF6 regulates GABAergic synapse development. Mol Brain 2020; 13:2. [PMID: 31907062 PMCID: PMC6945580 DOI: 10.1186/s13041-019-0543-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/23/2019] [Indexed: 01/05/2023] Open
Abstract
ADP ribosylation factors (ARFs) are a family of small GTPases composed of six members (ARF1-6) that control various cellular functions, including membrane trafficking and actin cytoskeletal rearrangement, in eukaryotic cells. Among them, ARF1 and ARF6 are the most studied in neurons, particularly at glutamatergic synapses, but their roles at GABAergic synapses have not been investigated. Here, we show that a subset of ARF6 protein is localized at GABAergic synapses in cultured hippocampal neurons. In addition, we found that knockdown (KD) of ARF6, but not ARF1, triggered a reduction in the number of GABAergic synaptic puncta in mature cultured neurons in an ARF activity-dependent manner. ARF6 KD also reduced GABAergic synaptic density in the mouse hippocampal dentate gyrus (DG) region. Furthermore, ARF6 KD in the DG increased seizure susceptibility in an induced epilepsy model. Viewed together, our results suggest that modulating ARF6 and its regulators could be a therapeutic strategy against brain pathologies involving hippocampal network dysfunction, such as epilepsy.
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Affiliation(s)
- Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyunsu Jung
- Division of Life Sciences, Korea University, Seoul, 02841, South Korea.,Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea.
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25
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Ibarluzea N, de la Hoz AB, Villate O, Llano I, Ocio I, Martí I, Guitart M, Gabau E, Andrade F, Gener B, Tejada MI. Targeted Next-Generation Sequencing in Patients with Suggestive X-Linked Intellectual Disability. Genes (Basel) 2020; 11:genes11010051. [PMID: 31906484 PMCID: PMC7017351 DOI: 10.3390/genes11010051] [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: 12/03/2019] [Revised: 12/19/2019] [Accepted: 12/30/2019] [Indexed: 12/28/2022] Open
Abstract
X-linked intellectual disability (XLID) is known to contribute up to 10% of intellectual disability (ID) in males and could explain the increased ratio of affected males observed in patients with ID. Over the past decade, next-generation sequencing has clearly stimulated the gene discovery process and has become part of the diagnostic procedure. We have performed targeted next-generation sequencing of 82 XLID genes on 61 non-related male patients with suggestive non-syndromic XLID. These patients were initially referred to the molecular genetics laboratory to exclude Fragile X Syndrome. The cohort includes 47 male patients with suggestive X-linked family history of ID meaning that they had half-brothers or maternal cousins or uncles affected; and 14 male patients with ID and affected brothers whose mothers show skewed X-inactivation. Sequencing data analysis identified 17 candidate variants in 16 patients. Seven families could be re-contacted and variant segregation analysis of the respective eight candidate variants was performed: HUWE1, IQSEC2, MAOA, MED12, PHF8, SLC6A8, SLC9A6, and SYN1. Our results show the utility of targeted next-generation sequencing in unravelling the genetic origin of XLID, especially in retrospective cases. Variant segregation and additional studies like RNA sequencing and biochemical assays also helped in re-evaluating and further classifying the genetic variants found.
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Affiliation(s)
- Nekane Ibarluzea
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Ana Belén de la Hoz
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Olatz Villate
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - Isabel Llano
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - Intzane Ocio
- Department of Paediatric Neurology, Araba University Hospital, Osakidetza Basque Health Service, 01009 Gasteiz, Spain
| | - Itxaso Martí
- Department of Paediatric Neurology, Donostia University Hospital, Osakidetza Basque Health Service, 20014 Donostia, Spain
| | - Miriam Guitart
- Genetics Laboratory, Paediatric Unit, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, 08208 Sabadell, Spain
| | - Elisabeth Gabau
- Genetics Laboratory, Paediatric Unit, Parc Taulí Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, 08208 Sabadell, Spain
| | - Fernando Andrade
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
| | - Blanca Gener
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
| | - María-Isabel Tejada
- Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain
- Spanish Consortium for Research on Rare Diseases (CIBERER), 28029 Madrid, Spain
- Genetics Service, Cruces University Hospital, Osakidetza Basque Health Service, 48903 Barakaldo, Spain
- Correspondence:
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26
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Lin L, Lyu Q, Kwan PY, Zhao J, Fan R, Chai A, Lai CSW, Chan YS, Shen X, Lai KO. The epilepsy and intellectual disability-associated protein TBC1D24 regulates the maintenance of excitatory synapses and animal behaviors. PLoS Genet 2020; 16:e1008587. [PMID: 32004315 PMCID: PMC7015432 DOI: 10.1371/journal.pgen.1008587] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 02/12/2020] [Accepted: 12/29/2019] [Indexed: 12/27/2022] Open
Abstract
Perturbation of synapse development underlies many inherited neurodevelopmental disorders including intellectual disability (ID). Diverse mutations on the human TBC1D24 gene are strongly associated with epilepsy and ID. However, the physiological function of TBC1D24 in the brain is not well understood, and there is a lack of genetic mouse model that mimics TBC1D24 loss-of-function for the study of animal behaviors. Here we report that TBC1D24 is present at the postsynaptic sites of excitatory synapses, where it is required for the maintenance of dendritic spines through inhibition of the small GTPase ARF6. Mice subjected to viral-mediated knockdown of TBC1D24 in the adult hippocampus display dendritic spine loss, deficits in contextual fear memory, as well as abnormal behaviors including hyperactivity and increased anxiety. Interestingly, we show that the protein stability of TBC1D24 is diminished by the disease-associated missense mutation that leads to F251L amino acid substitution. We further generate the F251L knock-in mice, and the homozygous mutants show increased neuronal excitability, spontaneous seizure and pre-mature death. Moreover, the heterozygous F251L knock-in mice survive into adulthood but display dendritic spine defects and impaired memory. Our findings therefore uncover a previously uncharacterized postsynaptic function of TBC1D24, and suggest that impaired dendritic spine maintenance contributes to the pathophysiology of individuals harboring TBC1D24 gene mutations. The F251L knock-in mice represent a useful animal model for investigation of the mechanistic link between TBC1D24 loss-of-function and neurodevelopmental disorders.
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Affiliation(s)
- Lianfeng Lin
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Quanwei Lyu
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Pui-Yi Kwan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Junjun Zhao
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Ruolin Fan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Anping Chai
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Cora Sau Wan Lai
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
| | - Ying-Shing Chan
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
| | - Xuting Shen
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Kwok-On Lai
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
- State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China
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27
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Choi MH, Yang JO, Min JS, Lee JJ, Jun SY, Lee YJ, Yoon JY, Jeon SJ, Byeon I, Kang JW, Kim NS. A Novel X-Linked Variant of IQSEC2 is Associated with Lennox-Gastaut Syndrome and Mild Intellectual Disability in Three Generations of a Korean Family. Genet Test Mol Biomarkers 2019; 24:54-58. [PMID: 31829726 DOI: 10.1089/gtmb.2019.0177] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Aim: Lennox-Gastaut syndrome (LGS) is a severe type of childhood-onset epilepsy with multiple types of seizures, specific discharges on electroencephalography, and intellectual disability. However, LGS-related genes are largely unknown. To identify causative genes related to LGS, we collected and analyzed data from a three-generation Korean family in which one member had LGS and two had intellectual disability. Methods: Genomic DNAs were extracted from blood samples of all participants and used in whole-exome sequencing (WES). Genetic variants were detected by the Genome Analysis Toolkit and confirmed by Sanger sequencing. Variant pathogenicity was evaluated by prediction programs and the American College of Medical Genetics criteria. The LGS patient had generalized slow spike-and-wave discharges, multiple types of seizures, and developmental delay. Results: Analyses of the WES data from the family revealed a novel variant (c.1048G>A, p.Ala350Thr) in the IQ motif and Sec7 domain 2 (IQSEC2). This variant is within a highly evolutionarily conserved IQ-like motif, indicating a decrease in the calmodulin-binding capacity or α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid transmission. The hemizygous variant in the male with LGS was a maternally inherited X-linked variant from the heterozygous maternal grandmother and mother, both of whom had intellectual disability. Conclusion: These findings indicate that the variant of IQSEC2 triggered both LGS and intellectual disability dependent on sex in this family. We report a novel X-linked inherited IQSEC2 variant for LGS and intellectual disability, which enhances the spectrum of variants in the IQ-like motif of IQSEC2.
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Affiliation(s)
- Min-Hyuk Choi
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Jin Ok Yang
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Ju-Sik Min
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Jeong-Ju Lee
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Soo-Young Jun
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Yong-Jae Lee
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Ji-Yong Yoon
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Su-Jin Jeon
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Iksu Byeon
- Korean BioInformation Center (KOBIC), Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
| | - Joon-Won Kang
- Department of Pediatrics and Medical Science, Chungnam National University Hospital, College of Medicine, Chungnam National University, Daejeon, Republic of Korea
| | - Nam-Soon Kim
- Rare-Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea.,Department of Functional Genomics, Korea University of Science and Technology (UST), Daejeon, Republic of Korea
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28
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Ansar M, Chung HL, Al-Otaibi A, Elagabani MN, Ravenscroft TA, Paracha SA, Scholz R, Abdel Magid T, Sarwar MT, Shah SF, Qaisar AA, Makrythanasis P, Marcogliese PC, Kamsteeg EJ, Falconnet E, Ranza E, Santoni FA, Aldhalaan H, Al-Asmari A, Faqeih EA, Ahmed J, Kornau HC, Bellen HJ, Antonarakis SE. Bi-allelic Variants in IQSEC1 Cause Intellectual Disability, Developmental Delay, and Short Stature. Am J Hum Genet 2019; 105:907-920. [PMID: 31607425 DOI: 10.1016/j.ajhg.2019.09.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/30/2022] Open
Abstract
We report two consanguineous families with probands that exhibit intellectual disability, developmental delay, short stature, aphasia, and hypotonia in which homozygous non-synonymous variants were identified in IQSEC1 (GenBank: NM_001134382.3). In a Pakistani family, the IQSEC1 segregating variant is c.1028C>T (p.Thr343Met), while in a Saudi Arabian family the variant is c.962G>A (p.Arg321Gln). IQSEC1-3 encode guanine nucleotide exchange factors for the small GTPase ARF6 and their loss affects a variety of actin-dependent cellular processes, including AMPA receptor trafficking at synapses. The ortholog of IQSECs in the fly is schizo and its loss affects growth cone guidance at the midline in the CNS, also an actin-dependent process. Overexpression of the reference IQSEC1 cDNA in wild-type flies is lethal, but overexpression of the two variant IQSEC1 cDNAs did not affect viability. Loss of schizo caused embryonic lethality that could be rescued to 2nd instar larvae by moderate expression of the human reference cDNA. However, the p.Arg321Gln and p.Thr343Met variants failed to rescue embryonic lethality. These data indicate that the variants behave as loss-of-function mutations. We also show that schizo in photoreceptors is required for phototransduction. Finally, mice with a conditional Iqsec1 deletion in cortical neurons exhibited an increased density of dendritic spines with an immature morphology. The phenotypic similarity of the affecteds and the functional experiments in flies and mice indicate that IQSEC1 variants are the cause of a recessive disease with intellectual disability, developmental delay, and short stature, and that axonal guidance and dendritic projection defects as well as dendritic spine dysgenesis may underlie disease pathogenesis.
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29
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Wang G, Zhang P, Mendu SK, Wang Y, Zhang Y, Kang X, Desai BN, Zhu JJ. Revaluation of magnetic properties of Magneto. Nat Neurosci 2019; 23:1047-1050. [PMID: 31570862 DOI: 10.1038/s41593-019-0473-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 07/23/2019] [Indexed: 01/08/2023]
Affiliation(s)
- Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Peng Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Suresh K Mendu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Yali Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Yajun Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Xi Kang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Bimal N Desai
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA.
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA.
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30
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Jackson MR, Loring KE, Homan CC, Thai MH, Määttänen L, Arvio M, Jarvela I, Shaw M, Gardner A, Gecz J, Shoubridge C. Heterozygous loss of function of IQSEC2/ Iqsec2 leads to increased activated Arf6 and severe neurocognitive seizure phenotype in females. Life Sci Alliance 2019; 2:2/4/e201900386. [PMID: 31439632 PMCID: PMC6706959 DOI: 10.26508/lsa.201900386] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 07/25/2019] [Accepted: 08/15/2019] [Indexed: 12/30/2022] Open
Abstract
Clinical presentations of mutations in the IQSEC2 gene on the X-chromosome initially implicated to cause non-syndromic intellectual disability (ID) in males have expanded to include early onset seizures in males as well as in females. The molecular pathogenesis is not well understood, nor the mechanisms driving disease expression in heterozygous females. Using a CRISPR/Cas9-edited Iqsec2 KO mouse model, we confirm the loss of Iqsec2 mRNA expression and lack of Iqsec2 protein within the brain of both founder and progeny mice. Both male (52%) and female (46%) Iqsec2 KO mice present with frequent and recurrent seizures. Focusing on Iqsec2 KO heterozygous female mice, we demonstrate increased hyperactivity, altered anxiety and fear responses, decreased social interactions, delayed learning capacity and decreased memory retention/novel recognition, recapitulating psychiatric issues, autistic-like features, and cognitive deficits present in female patients with loss-of-function IQSEC2 variants. Despite Iqsec2 normally acting to activate Arf6 substrate, we demonstrate that mice modelling the loss of Iqsec2 function present with increased levels of activated Arf6. We contend that loss of Iqsec2 function leads to altered regulation of activated Arf6-mediated responses to synaptic signalling and immature synaptic networks. We highlight the importance of IQSEC2 function for females by reporting a novel nonsense variant c.566C > A, p.(S189*) in an elderly female patient with profound intellectual disability, generalised seizures, and behavioural disturbances. Our human and mouse data reaffirm IQSEC2 as another disease gene with an unexpected X-chromosome heterozygous female phenotype. Our Iqsec2 mouse model recapitulates the phenotypes observed in human patients despite the differences in the IQSEC2/Iqsec2 gene X-chromosome inactivation between the species.
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Affiliation(s)
- Matilda R Jackson
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia.,Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Karagh E Loring
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia.,Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Claire C Homan
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Monica Hn Thai
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia
| | - Laura Määttänen
- Department of Child Neurology, Turku University Hospital, Turku, Finland
| | - Maria Arvio
- Department of Child Neurology, Turku University Hospital, Turku, Finland.,Joint Authority for Päijät-Häme Social and Health Care, Lahti, Finland.,PEDEGO, Oulu University Hospital, Oulu, Finland
| | - Irma Jarvela
- Department of Medical Genetics, University of Helsinki, Helsinki, Finland
| | - Marie Shaw
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Alison Gardner
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - Jozef Gecz
- Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia.,South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Cheryl Shoubridge
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, Australia .,Department of Paediatrics, Robinson Research Institute, University of Adelaide, Adelaide, Australia
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31
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Levy NS, Umanah GKE, Rogers EJ, Jada R, Lache O, Levy AP. IQSEC2-Associated Intellectual Disability and Autism. Int J Mol Sci 2019; 20:ijms20123038. [PMID: 31234416 PMCID: PMC6628259 DOI: 10.3390/ijms20123038] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 06/19/2019] [Indexed: 01/02/2023] Open
Abstract
Mutations in IQSEC2 cause intellectual disability (ID), which is often accompanied by seizures and autism. A number of studies have shown that IQSEC2 is an abundant protein in excitatory synapses and plays an important role in neuronal development as well as synaptic plasticity. Here, we review neuronal IQSEC2 signaling with emphasis on those aspects likely to be involved in autism. IQSEC2 is normally bound to N-methyl-D-aspartate (NMDA)-type glutamate receptors via post synaptic density protein 95 (PSD-95). Activation of NMDA receptors results in calcium ion influx and binding to calmodulin present on the IQSEC2 IQ domain. Calcium/calmodulin induces a conformational change in IQSEC2 leading to activation of the SEC7 catalytic domain. GTP is exchanged for GDP on ADP ribosylation factor 6 (ARF6). Activated ARF6 promotes downregulation of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors through a c-jun N terminal kinase (JNK)-mediated pathway. NMDA receptors, AMPA receptors, and PSD-95 are all known to be adversely affected in autism. An IQSEC2 transgenic mouse carrying a constitutively active mutation (A350V) shows autistic features and reduced levels of surface AMPA receptor subunit GluA2. Sec7 activity and AMPA receptor recycling are presented as two targets, which may respond to drug treatment in IQSEC2-associated ID and autism.
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Affiliation(s)
- Nina S Levy
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - George K E Umanah
- Department of Neurology, Johns Hopkins University, Baltimore, MD 21205, USA.
| | - Eli J Rogers
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - Reem Jada
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - Orit Lache
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
| | - Andrew P Levy
- Technion Israel Institute of Technology, 1 Efron St., Haifa, 3525422, Israel.
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32
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Rogers EJ, Jada R, Schragenheim-Rozales K, Sah M, Cortes M, Florence M, Levy NS, Moss R, Walikonis RS, Palty R, Shalgi R, Lichtman D, Kavushansky A, Gerges NZ, Kahn I, Umanah GKE, Levy AP. An IQSEC2 Mutation Associated With Intellectual Disability and Autism Results in Decreased Surface AMPA Receptors. Front Mol Neurosci 2019; 12:43. [PMID: 30842726 PMCID: PMC6391579 DOI: 10.3389/fnmol.2019.00043] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/01/2019] [Indexed: 12/30/2022] Open
Abstract
We have recently described an A350V mutation in IQSEC2 associated with intellectual disability, autism and epilepsy. We sought to understand the molecular pathophysiology of this mutation with the goal of developing targets for drug intervention. We demonstrate here that the A350V mutation results in interference with the binding of apocalmodulin to the IQ domain of IQSEC2. We further demonstrate that this mutation results in constitutive activation of the guanine nucleotide exchange factor (GEF) activity of IQSEC2 resulting in increased production of the active form of Arf6. In a CRISPR generated mouse model of the A350V IQSEC2 mutation, we demonstrate that the surface expression of GluA2 AMPA receptors in mouse hippocampal tissue was significantly reduced in A350V IQSEC2 mutant mice compared to wild type IQSEC2 mice and that there is a significant reduction in basal synaptic transmission in the hippocampus of A350V IQSEC2 mice compared to wild type IQSEC2 mice. Finally, the A350V IQSEC2 mice demonstrated increased activity, abnormal social behavior and learning as compared to wild type IQSEC2 mice. These findings suggest a model of how the A350V mutation in IQSEC2 may mediate disease with implications for targets for drug therapy. These studies provide a paradigm for a personalized approach to precision therapy for a disease that heretofore has no therapy.
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Affiliation(s)
- Eli J Rogers
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reem Jada
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | | | - Megha Sah
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Marisol Cortes
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Matthew Florence
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Nina S Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Rachel Moss
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Randall S Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States
| | - Raz Palty
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Reut Shalgi
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Daniela Lichtman
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Alexandra Kavushansky
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - Nashaat Z Gerges
- Department of Biopharmaceutical Sciences and Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Itamar Kahn
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
| | - George K E Umanah
- Department of Neurology, Johns Hopkins University, Baltimore, MD, United States
| | - Andrew P Levy
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel
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33
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Shoubridge C, Harvey RJ, Dudding-Byth T. IQSEC2mutation update and review of the female-specific phenotype spectrum including intellectual disability and epilepsy. Hum Mutat 2018; 40:5-24. [DOI: 10.1002/humu.23670] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/11/2018] [Accepted: 10/15/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Cheryl Shoubridge
- Department of Paediatrics; University of Adelaide; Adelaide South Australia 5005 Australia
- Robinson Research Institute; University of Adelaide; Adelaide South Australia 5005 Australia
| | - Robert J. Harvey
- School of Health and Sport Sciences; University of the Sunshine Coast; Maroochydore DC Queensland 4558 Australia
- Sunshine Coast Health Institute; Birtinya Queensland 4575 Australia
| | - Tracy Dudding-Byth
- NSW Genetics of Learning Disability Service; Hunter New England Health Service; New South Wales 2298 Australia
- Grow-Up-Well Priority Research Centre; University of Newcastle; Newcastle New South Wales 2308 Australia
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34
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Früh S, Tyagarajan SK, Campbell B, Bosshard G, Fritschy JM. The catalytic function of the gephyrin-binding protein IQSEC3 regulates neurotransmitter-specific matching of pre- and post-synaptic structures in primary hippocampal cultures. J Neurochem 2018; 147:477-494. [DOI: 10.1111/jnc.14572] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 08/05/2018] [Accepted: 08/08/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Simon Früh
- Institute of Pharmacology and Toxicology; University of Zurich; Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and Federal Institute of Technology (ETH) Zurich; Zurich Switzerland
| | - Shiva K. Tyagarajan
- Institute of Pharmacology and Toxicology; University of Zurich; Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and Federal Institute of Technology (ETH) Zurich; Zurich Switzerland
| | - Benjamin Campbell
- Institute of Pharmacology and Toxicology; University of Zurich; Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and Federal Institute of Technology (ETH) Zurich; Zurich Switzerland
| | - Giovanna Bosshard
- Institute of Pharmacology and Toxicology; University of Zurich; Zurich Switzerland
| | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zurich; Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and Federal Institute of Technology (ETH) Zurich; Zurich Switzerland
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35
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Changes in the Synaptic Proteome in Tauopathy and Rescue of Tau-Induced Synapse Loss by C1q Antibodies. Neuron 2018; 100:1322-1336.e7. [PMID: 30392797 DOI: 10.1016/j.neuron.2018.10.014] [Citation(s) in RCA: 282] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/15/2018] [Accepted: 10/05/2018] [Indexed: 12/19/2022]
Abstract
Synapse loss and Tau pathology are hallmarks of Alzheimer's disease (AD) and other tauopathies, but how Tau pathology causes synapse loss is unclear. We used unbiased proteomic analysis of postsynaptic densities (PSDs) in Tau-P301S transgenic mice to identify Tau-dependent alterations in synapses prior to overt neurodegeneration. Multiple proteins and pathways were altered in Tau-P301S PSDs, including depletion of a set of GTPase-regulatory proteins that leads to actin cytoskeletal defects and loss of dendritic spines. Furthermore, we found striking accumulation of complement C1q in the PSDs of Tau-P301S mice and AD patients. At synapses, C1q decorated perisynaptic membranes, accumulated in correlation with phospho-Tau, and was associated with augmented microglial engulfment of synapses and decline of synapse density. A C1q-blocking antibody inhibited microglial synapse removal in cultured neurons and in Tau-P301S mice, rescuing synapse density. Thus, inhibiting complement-mediated synapse removal by microglia could be a potential therapeutic target for Tau-associated neurodegeneration.
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36
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Abstract
Adult central nervous system (CNS) axons do not regenerate after injury because of extrinsic inhibitory factors, and a low intrinsic capacity for axon growth. Developing CNS neurons have a better regenerative ability, but lose this with maturity. This mini-review summarises recent findings which suggest one reason for regenerative failure is the selective distribution of growth machinery away from axons as CNS neurons mature. These studies demonstrate roles for the small GTPases ARF6 and Rab11 as intrinsic regulators of polarised transport and axon regeneration. ARF6 activation prevents the axonal transport of integrins in Rab11 endosomes in mature CNS axons. Decreasing ARF6 activation permits axonal transport, and increases regenerative ability. The findings suggest new targets for promoting axon regeneration after CNS injury.
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Affiliation(s)
- Bart Nieuwenhuis
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge , Forvie Site, Robinson Way, Cambridge, UK.,Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW) , Amsterdam, The Netherlands
| | - Richard Eva
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge , Forvie Site, Robinson Way, Cambridge, UK
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37
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Zhang L, Zhang P, Wang G, Zhang H, Zhang Y, Yu Y, Zhang M, Xiao J, Crespo P, Hell JW, Lin L, Huganir RL, Zhu JJ. Ras and Rap Signal Bidirectional Synaptic Plasticity via Distinct Subcellular Microdomains. Neuron 2018; 98:783-800.e4. [PMID: 29706584 PMCID: PMC6192044 DOI: 10.1016/j.neuron.2018.03.049] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/12/2018] [Accepted: 03/27/2018] [Indexed: 11/16/2022]
Abstract
How signaling molecules achieve signal diversity and specificity is a long-standing cell biology question. Here we report the development of a targeted delivery method that permits specific expression of homologous Ras-family small GTPases (i.e., Ras, Rap2, and Rap1) in different subcellular microdomains, including the endoplasmic reticulum, lipid rafts, bulk membrane, lysosomes, and Golgi complex, in rodent hippocampal CA1 neurons. The microdomain-targeted delivery, combined with multicolor fluorescence protein tagging and high-resolution dual-quintuple simultaneous patch-clamp recordings, allows systematic analysis of microdomain-specific signaling. The analysis shows that Ras signals long-term potentiation via endoplasmic reticulum PI3K and lipid raft ERK, whereas Rap2 and Rap1 signal depotentiation and long-term depression via bulk membrane JNK and lysosome p38MAPK, respectively. These results establish an effective subcellular microdomain-specific targeted delivery method and unveil subcellular microdomain-specific signaling as the mechanism for homologous Ras and Rap to achieve signal diversity and specificity to control multiple forms of synaptic plasticity.
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Affiliation(s)
- Lei Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Peng Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Huaye Zhang
- Department of Microbiology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Yajun Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yilin Yu
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Mingxu Zhang
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA; Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Jian Xiao
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Piero Crespo
- Instituto de Biomedicina y Biotecnología de Cantabriaand CIBERONC, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Cantabria, Santander 39011, Spain
| | - Johannes W Hell
- Department of Pharmacology, University of Iowa, Iowa City, IA 52242, USA; Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Li Lin
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China.
| | - Richard L Huganir
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA 22908, USA; School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China; School of Medicine, Ningbo University, Ningbo 315010, China; Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen, 6525 EN, Nijmegen, the Netherlands
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38
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Petersen A, Brown JC, Gerges NZ. BRAG1/IQSEC2 as a regulator of small GTPase-dependent trafficking. Small GTPases 2018; 11:1-7. [PMID: 29363391 DOI: 10.1080/21541248.2017.1361898] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Precise trafficking events, such as those that underlie synaptic transmission and plasticity, require complex regulation. G-protein signaling plays an essential role in the regulation of membrane and protein trafficking. However, it is not well understood how small GTPases and their regulatory proteins coordinate such specific events. Our recent publication focused on a highly abundant synaptic GEF, BRAG1, whose physiologic relevance was unknown. We find that BRAG1s GEF activity is required for activity-dependent trafficking of AMPARs. Moreover, BRAG1 bidirectionally regulates synaptic transmission in a manner independent of this activity. In addition to the GEF domain, BRAG1 contains several functional domains whose roles are not yet understood but may mediate protein-protein interactions and regulatory effects necessary for its role in regulation of AMPAR trafficking. In this commentary, we explore the potential for BRAG1 to provide specificity of small GTPase signaling, coordinating activity-dependent activation of small GTPase activity with signaling and scaffolding molecules involved in trafficking through its GEF activity and other functional domains.
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Affiliation(s)
- Amber Petersen
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Joshua C Brown
- Department of Psychiatry and Behavioral Science, Medical University of South Carolina, Charleston, SC, USA
| | - Nashaat Z Gerges
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Department of Biopharmaceutical Sciences, School of Pharmacy, The Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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39
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Lim CS, Wen C, Sheng Y, Wang G, Zhou Z, Wang S, Zhang H, Ye A, Zhu JJ. Piconewton-Scale Analysis of Ras-BRaf Signal Transduction with Single-Molecule Force Spectroscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2017; 13:10.1002/smll.201701972. [PMID: 28809097 PMCID: PMC6272124 DOI: 10.1002/smll.201701972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 07/10/2017] [Indexed: 06/07/2023]
Abstract
Intermolecular interactions dominate the behavior of signal transduction in various physiological and pathological cell processes, yet assessing these interactions remains a challenging task. Here, this study reports a single-molecule force spectroscopic method that enables functional delineation of two interaction sites (≈35 pN and ≈90 pN) between signaling effectors Ras and BRaf in the canonical mitogen-activated protein kinase (MAPK) pathway. This analysis reveals mutations on BRaf at Q257 and A246, two sites frequently linked to cardio-faciocutaneous syndrome, result in ≈10-30 pN alterations in RasBRaf intermolecular binding force. The magnitude of changes in RasBRaf binding force correlates with the size of alterations in protein affinity and in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-sensitive glutamate receptor (-R)-mediated synaptic transmission in neurons expressing replacement BRaf mutants, and predicts the extent of learning impairments in animals expressing replacement BRaf mutants. These results establish single-molecule force spectroscopy as an effective platform for evaluating the piconewton-level interaction of signaling molecules and predicting the behavior outcome of signal transduction.
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Affiliation(s)
- Chae-Seok Lim
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Cheng Wen
- School of Electronic Engineering and Computer Science, Peking University, Beijing, 100871, China
| | - Yanghui Sheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Undergraduate Class of 2011, Yuanpei Honors College, Peking University, Beijing, 100871, China
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Guangfu Wang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Zhuan Zhou
- Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Shiqiang Wang
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Huaye Zhang
- Department of Microbiology and Center for Cell Signaling, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Anpei Ye
- School of Electronic Engineering and Computer Science, Peking University, Beijing, 100871, China
| | - J Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Institute of Neuroscience, Zhejiang University School of Medicine, Hangzhou, 310058, China
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6525, EN, Nijmegen, Netherlands
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40
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Um JW. Synaptic functions of the IQSEC family of ADP-ribosylation factor guanine nucleotide exchange factors. Neurosci Res 2017; 116:54-59. [DOI: 10.1016/j.neures.2016.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 06/15/2016] [Accepted: 06/15/2016] [Indexed: 01/08/2023]
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41
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Abstract
The IQSec/BRAG proteins are a subfamily of Arf-nucleotide exchange factors. Since their discovery almost 15 y ago, the BRAGs have been reported to be involved in diverse physiological processes from myoblast fusion, neuronal pathfinding and angiogenesis, to pathophysiological processes including X-linked intellectual disability and tumor metastasis. In this review we will address how, in each of these situations, the BRAGs are thought to regulate the surface levels of adhesive and signaling receptors. While in most cases BRAGs are thought to enhance the endocytosis of these receptors, how they achieve this remains unclear. Similarly, while all 3 BRAG proteins contain calmodulin-binding IQ motifs, little is known about how their activities might be regulated by calcium. These are some of the questions that are likely to form the basis of future research.
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Affiliation(s)
- Ryan S D'Souza
- a Department of Cell Biology , University of Virginia Health System , Charlottesville , VA , USA
| | - James E Casanova
- a Department of Cell Biology , University of Virginia Health System , Charlottesville , VA , USA
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42
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Walkup WG, Mastro TL, Schenker LT, Vielmetter J, Hu R, Iancu A, Reghunathan M, Bannon BD, Kennedy MB. A model for regulation by SynGAP-α1 of binding of synaptic proteins to PDZ-domain 'Slots' in the postsynaptic density. eLife 2016; 5. [PMID: 27623146 PMCID: PMC5040590 DOI: 10.7554/elife.16813] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 09/09/2016] [Indexed: 12/16/2022] Open
Abstract
SynGAP is a Ras/Rap GTPase-activating protein (GAP) that is a major constituent of postsynaptic densities (PSDs) from mammalian forebrain. Its α1 isoform binds to all three PDZ (PSD-95, Discs-large, ZO-1) domains of PSD-95, the principal PSD scaffold, and can occupy as many as 15% of these PDZ domains. We present evidence that synGAP-α1 regulates the composition of the PSD by restricting binding to the PDZ domains of PSD-95. We show that phosphorylation by Ca2+/calmodulin-dependent protein kinase II (CaMKII) and Polo-like kinase-2 (PLK2) decreases its affinity for the PDZ domains by several fold, which would free PDZ domains for occupancy by other proteins. Finally, we show that three critical postsynaptic signaling proteins that bind to the PDZ domains of PSD-95 are present in higher concentration in PSDs isolated from mice with a heterozygous deletion of synGAP.
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Affiliation(s)
- Ward G Walkup
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Tara L Mastro
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Leslie T Schenker
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Jost Vielmetter
- Beckman Institute Protein Expression Center, California Institute of Technology, Pasadena, United States
| | - Rebecca Hu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Ariella Iancu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Meera Reghunathan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Barry Dylan Bannon
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Mary B Kennedy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
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43
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Sheng Y, Zhang L, Su SC, Tsai LH, Julius Zhu J. Cdk5 is a New Rapid Synaptic Homeostasis Regulator Capable of Initiating the Early Alzheimer-Like Pathology. Cereb Cortex 2016; 26:2937-51. [PMID: 26088971 PMCID: PMC4898661 DOI: 10.1093/cercor/bhv032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase implicated in synaptic plasticity, behavior, and cognition, yet its synaptic function remains poorly understood. Here, we report that physiological Cdk5 signaling in rat hippocampal CA1 neurons regulates homeostatic synaptic transmission using an unexpectedly rapid mechanism that is different from all known slow homeostatic regulators, such as beta amyloid (Aβ) and activity-regulated cytoskeleton-associated protein (Arc, aka Arg3.1). Interestingly, overproduction of the potent Cdk5 activator p25 reduces synapse density, and dynamically regulates synaptic size by suppressing or enhancing Aβ/Arc production. Moreover, chronic overproduction of p25, seen in Alzheimer's patients, induces initially concurrent reduction in synapse density and increase in synaptic size characteristic of the early Alzheimer-like pathology, and later persistent synapse elimination in intact brains. These results identify Cdk5 as the regulator of a novel rapid form of homeostasis at central synapses and p25 as the first molecule capable of initiating the early Alzheimer's synaptic pathology.
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Affiliation(s)
- Yanghui Sheng
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
- Undergraduate Class of 2011, Yuanpei Honors College, Peking University, Beijing100871, China
- Current address: Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Lei Zhang
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Susan C. Su
- Picower Institute for Learning and Memory and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J. Julius Zhu
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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44
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45
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Brown JC, Petersen A, Zhong L, Himelright ML, Murphy JA, Walikonis RS, Gerges NZ. Bidirectional regulation of synaptic transmission by BRAG1/IQSEC2 and its requirement in long-term depression. Nat Commun 2016; 7:11080. [PMID: 27009485 PMCID: PMC4820844 DOI: 10.1038/ncomms11080] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/16/2016] [Indexed: 01/09/2023] Open
Abstract
Dysfunction of the proteins regulating synaptic function can cause synaptic plasticity imbalance that underlies neurological disorders such as intellectual disability. A study found that four distinct mutations within BRAG1, an Arf-GEF synaptic protein, each led to X-chromosome-linked intellectual disability (XLID). Although the physiological functions of BRAG1 are poorly understood, each of these mutations reduces BRAG1's Arf-GEF activity. Here we show that BRAG1 is required for the activity-dependent removal of AMPA receptors in rat hippocampal pyramidal neurons. Moreover, we show that BRAG1 bidirectionally regulates synaptic transmission. On one hand, BRAG1 is required for the maintenance of synaptic transmission. On the other hand, BRAG1 expression enhances synaptic transmission, independently of BRAG1 Arf-GEF activity or neuronal activity, but dependently on its C-terminus interactions. This study demonstrates a dual role of BRAG1 in synaptic function and highlights the functional relevance of reduced BRAG1 Arf-GEF activity as seen in the XLID-associated human mutations.
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Affiliation(s)
- Joshua C Brown
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
| | - Amber Petersen
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
| | - Ling Zhong
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
| | - Miranda L Himelright
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269 USA
| | - Jessica A Murphy
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269 USA
| | - Randall S Walikonis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut 06269 USA
| | - Nashaat Z Gerges
- Department of Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, Wisconsin 53132 USA
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46
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Um JW, Choii G, Park D, Kim D, Jeon S, Kang H, Mori T, Papadopoulos T, Yoo T, Lee Y, Kim E, Tabuchi K, Ko J. IQ Motif and SEC7 Domain-containing Protein 3 (IQSEC3) Interacts with Gephyrin to Promote Inhibitory Synapse Formation. J Biol Chem 2016; 291:10119-30. [PMID: 27002143 DOI: 10.1074/jbc.m115.712893] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Indexed: 01/13/2023] Open
Abstract
Gephyrin is a central scaffold protein that mediates development, function, and plasticity of mammalian inhibitory synapses by interacting with various inhibitory synaptic proteins. Here, we show that IQSEC3, a guanine nucleotide exchange factor for ARF6, directly interacts with gephyrin, an interaction that is critical for the inhibitory synapse localization of IQSEC3. Overexpression of IQSEC3 increases inhibitory, but not excitatory, synapse density in a guanine nucleotide exchange factor activity-dependent manner. Conversely, knockdown of IQSEC3 decreases size of gephyrin cluster without altering gephyrin puncta density. Collectively, these data reveal that IQSEC3 acts together with gephyrin to regulate inhibitory synapse development.
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Affiliation(s)
- Ji Won Um
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea, the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Gayoung Choii
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Dongseok Park
- the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Dongwook Kim
- the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Sangmin Jeon
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea
| | - Hyeyeon Kang
- the Department of Physiology and BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Takuma Mori
- the Shinshu University School of Medicine, Matsumoto 390-8621, Japan
| | - Theofilos Papadopoulos
- the Department of Molecular Biology, University Medicine Göttingen, Göttingen 37075, Germany
| | - Taesun Yoo
- the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Yeunkum Lee
- the Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 305-701, Republic of Korea, and
| | - Eunjoon Kim
- the Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea, the Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 305-701, Republic of Korea, and
| | - Katsuhiko Tabuchi
- the Shinshu University School of Medicine, Matsumoto 390-8621, Japan, PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Jaewon Ko
- From the Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea,
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Elagabani MN, Briševac D, Kintscher M, Pohle J, Köhr G, Schmitz D, Kornau HC. Subunit-selective N-Methyl-d-aspartate (NMDA) Receptor Signaling through Brefeldin A-resistant Arf Guanine Nucleotide Exchange Factors BRAG1 and BRAG2 during Synapse Maturation. J Biol Chem 2016; 291:9105-18. [PMID: 26884337 DOI: 10.1074/jbc.m115.691717] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Indexed: 11/06/2022] Open
Abstract
The maturation of glutamatergic synapses in the CNS is regulated by NMDA receptors (NMDARs) that gradually change from a GluN2B- to a GluN2A-dominated subunit composition during postnatal development. Here we show that NMDARs control the activity of the small GTPase ADP-ribosylation factor 6 (Arf6) by consecutively recruiting two related brefeldin A-resistant Arf guanine nucleotide exchange factors, BRAG1 and BRAG2, in a GluN2 subunit-dependent manner. In young cortical cultures, GluN2B and BRAG1 tonically activated Arf6. In mature cultures, Arf6 was activated through GluN2A and BRAG2 upon NMDA treatment, whereas the tonic Arf6 activation was not detectable any longer. This shift in Arf6 regulation and the associated drop in Arf6 activity were reversed by a knockdown of BRAG2. Given their sequential recruitment during development, we examined whether BRAG1 and BRAG2 influence synaptic currents in hippocampal CA1 pyramidal neurons using patch clamp recordings in acute slices from mice at different ages. The number of AMPA receptor (AMPAR) miniature events was reduced by depletion of BRAG1 but not by depletion of BRAG2 during the first 2 weeks after birth. In contrast, depletion of BRAG2 during postnatal weeks 4 and 5 reduced the number of AMPAR miniature events and compromised the quantal sizes of both AMPAR and NMDAR currents evoked at Schaffer collateral synapses. We conclude that both Arf6 activation through GluN2B-BRAG1 during early development and the transition from BRAG1- to BRAG2-dependent Arf6 signaling induced by the GluN2 subunit switch are critical for the development of mature glutamatergic synapses.
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Affiliation(s)
- Mohammad Nael Elagabani
- From the Neuroscience Research Center (NWFZ) and Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany and
| | - Dušica Briševac
- From the Neuroscience Research Center (NWFZ) and Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany and
| | | | - Jörg Pohle
- the Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159 Mannheim, Germany
| | - Georg Köhr
- the Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159 Mannheim, Germany
| | | | - Hans-Christian Kornau
- From the Neuroscience Research Center (NWFZ) and Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany and
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Tagliatti E, Fadda M, Falace A, Benfenati F, Fassio A. Arf6 regulates the cycling and the readily releasable pool of synaptic vesicles at hippocampal synapse. eLife 2016; 5. [PMID: 26731518 PMCID: PMC4764570 DOI: 10.7554/elife.10116] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 01/04/2016] [Indexed: 01/29/2023] Open
Abstract
Recycling of synaptic vesicles (SVs) is a fundamental step in the process of neurotransmission. Endocytosed SV can travel directly into the recycling pool or recycle through endosomes but little is known about the molecular actors regulating the switch between these SV recycling routes. ADP ribosylation factor 6 (Arf6) is a small GTPase known to participate in constitutive trafficking between plasma membrane and early endosomes. Here, we have morphologically and functionally investigated Arf6-silenced hippocampal synapses and found an activity dependent accumulation of synaptic endosome-like organelles and increased release-competent docked SVs. These features were phenocopied by pharmacological blockage of Arf6 activation. The data reveal an unexpected role for this small GTPase in reducing the size of the readily releasable pool of SVs and in channeling retrieved SVs toward direct recycling rather than endosomal sorting. We propose that Arf6 acts at the presynapse to define the fate of an endocytosed SV. DOI:http://dx.doi.org/10.7554/eLife.10116.001 Communication between neurons takes place at cell-to-cell contacts called synapses. Each synapse is formed between one neuron that sends the message, and another neuron that receives it. The neuron before the synapse – called the presynaptic neuron – contains packets called synaptic vesicles, which are full of chemical messengers ready to be released upon activity. Accurate communication between neurons relies on the exact composition, and organized trafficking, of the synaptic vesicles when the neuron is active. Synapses also contain bigger structures, called endosomal structures, which may represent an intermediate station in which synaptic vesicle composition is controlled. However, the trafficking of synaptic vesicles through the endosomal structures is poorly understood. Now, Tagliatti, Fadda et al. have revealed that a protein called Arf6 plays an important role in presynaptic neurons. The experiments involved rat neurons grown in the laboratory, and showed that Arf6 controls both the number of synaptic vesicles ready to be released and the trafficking of synaptic vesicles via endosomal structures in active neurons. The next step following on from these findings is to understand how Arf6 exerts its effects and how this protein is regulated in the presynaptic neuron. DOI:http://dx.doi.org/10.7554/eLife.10116.002
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Affiliation(s)
- Erica Tagliatti
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Manuela Fadda
- Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Antonio Falace
- Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Fabio Benfenati
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Anna Fassio
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
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Liu F, Guo H, Ou M, Hou X, Sun G, Gong W, Jing H, Tan Q, Xue W, Dai Y, Sui W. ARHGAP4 mutated in a Chinese intellectually challenged family. Gene 2015; 578:205-9. [PMID: 26707211 DOI: 10.1016/j.gene.2015.12.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 12/05/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Mental retardation is characterized by lower intelligence compared to the average intelligence of persons the same age. These patients have low adaptive capacity acquired by society. The genetic factors of causing MR include monogenic disease, chromosome structural aberration, and chromosome number aberration and so on. We explored the cause of a Chinese family suffering from mental retardation. METHODS We used karyotyping technology to determine the karyotype of the proband, and we used FISH to verify the result of the karyotyping. We used whole-exome sequencing to identify the disease-causing gene and used Sanger sequencing to verify the result of whole-exome sequencing to assess the family's gene expression. RESULTS The G-banding of the karyotype revealed that the patient's karyotype is 46, XY. FISH revealed that the patient does not have a trisomy syndrome. The karyotype of the proband is normal. Using whole-exome sequencing, we identified 108,767 variants in the exome gene of the patient, including 101,787 SNPs and 6980 InDels. Combining clinical information and bioinformatics analysis, including databases filtering and SIFT analysis, we found ARHGAP4 in X chromosome was candidate MR disease-causing gene. PCR and Sanger sequencing results were consistent with whole-exome sequencing. ARHGAP4 (T491M) mutation was present in the genome of the proband and his mother is a carrier, while his father, sister, and brother do not carry this mutation. CONCLUSION According to clinical information, whole-exome sequencing results and Sanger verification results, ARHGAP4 (T491M) mutation may be disease-causing gene of the MR patient. The relation between ARHGAP4 mutation and MR clinical characteristic is needed to be illuminated with participation of more MR patients.
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Affiliation(s)
- Fuhua Liu
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China; College of Life Science, Guangxi Normal University, 541004 Guilin, Guangxi, China
| | - Hui Guo
- Clinical Medical Research Center, the Second Clinical Medical College of Jinan University, Shenzhen People's Hospital, 518020, Shenzhen, Guangdong, China
| | - Minglin Ou
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Xianliang Hou
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Guoping Sun
- Lab. Center, Shenzhen Pingshan People's Hospital, Shenzhen, Guangdong 518118, China
| | - Weiwei Gong
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Huanyun Jing
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Qiupei Tan
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Wen Xue
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Yong Dai
- Clinical Medical Research Center, the Second Clinical Medical College of Jinan University, Shenzhen People's Hospital, 518020, Shenzhen, Guangdong, China.
| | - Weiguo Sui
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China.
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Ctip2-, Satb2-, Prox1-, and GAD65-Expressing Neurons in Rat Cultures: Preponderance of Single- and Double-Positive Cells, and Cell Type-Specific Expression of Neuron-Specific Gene Family Members, Nsg-1 (NEEP21) and Nsg-2 (P19). PLoS One 2015; 10:e0140010. [PMID: 26465886 PMCID: PMC4605768 DOI: 10.1371/journal.pone.0140010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/31/2015] [Indexed: 11/19/2022] Open
Abstract
The brain consists of many distinct neuronal cell types, but which cell types are present in widely used primary cultures of embryonic rodent brain is often not known. We characterized how abundantly four cell type markers (Ctip2, Satb2, Prox1, GAD65) were represented in cultured rat neurons, how easily neurons expressing different markers can be transfected with commonly used plasmids, and whether neuronal-enriched endosomal proteins Nsg-1 (NEEP21) and Nsg-2 (P19) are ubiquitously expressed in all types of cultured neurons. We found that cultured neurons stably maintain cell type identities that are reflective of cell types in vivo. This includes neurons maintaining simultaneous expression of two transcription factors, such as Ctip2+/Satb2+ or Prox1+/Ctip2+ double-positive cells, which have also been described in vivo. Secondly, we established the superior efficiency of CAG promoters for both Lipofectamine-mediated transfection as well as for electroporation. Thirdly, we discovered that Nsg-1 and Nsg-2 were not expressed equally in all neurons: whereas high levels of both Nsg-1 and Nsg-2 were found in Satb2-, Ctip2-, and GAD65-positive neurons, Prox1-positive neurons in hippocampal cultures expressed low levels of both. Our findings thus highlight the importance of identifying neuronal cell types for doing cell biology in cultured neurons: Keeping track of neuronal cell type might uncover effects in assays that might otherwise be masked by the mixture of responsive and non-responsive neurons in the dish.
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