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Molinaro G, Bowles JE, Croom K, Gonzalez D, Mirjafary S, Birnbaum SG, Razak KA, Gibson JR, Huber KM. Female-specific dysfunction of sensory neocortical circuits in a mouse model of autism mediated by mGluR5 and estrogen receptor α. Cell Rep 2024; 43:114056. [PMID: 38581678 PMCID: PMC11112681 DOI: 10.1016/j.celrep.2024.114056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 01/26/2024] [Accepted: 03/20/2024] [Indexed: 04/08/2024] Open
Abstract
Little is known of the brain mechanisms that mediate sex-specific autism symptoms. Here, we demonstrate that deletion of the autism spectrum disorder (ASD)-risk gene, Pten, in neocortical pyramidal neurons (NSEPten knockout [KO]) results in robust cortical circuit hyperexcitability selectively in female mice observed as prolonged spontaneous persistent activity states. Circuit hyperexcitability in females is mediated by metabotropic glutamate receptor 5 (mGluR5) and estrogen receptor α (ERα) signaling to mitogen-activated protein kinases (Erk1/2) and de novo protein synthesis. Pten KO layer 5 neurons have a female-specific increase in mGluR5 and mGluR5-dependent protein synthesis. Furthermore, mGluR5-ERα complexes are generally elevated in female cortices, and genetic reduction of ERα rescues enhanced circuit excitability, protein synthesis, and neuron size selectively in NSEPten KO females. Female NSEPten KO mice display deficits in sensory processing and social behaviors as well as mGluR5-dependent seizures. These results reveal mechanisms by which sex and a high-confidence ASD-risk gene interact to affect brain function and behavior.
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Affiliation(s)
- Gemma Molinaro
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jacob E Bowles
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Katilynne Croom
- Graduate Neuroscience Program, University of California, Riverside, Riverside, CA, USA
| | - Darya Gonzalez
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Saba Mirjafary
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Shari G Birnbaum
- Department of Psychiatry, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Khaleel A Razak
- Graduate Neuroscience Program, University of California, Riverside, Riverside, CA, USA; Department of Psychology, University of California, Riverside, Riverside, CA, USA
| | - Jay R Gibson
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA
| | - Kimberly M Huber
- Department of Neuroscience, O'Donnell Brain Institute, UT Southwestern Medical Center, Dallas, TX, USA.
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2
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Molinaro G, Bowles JE, Croom K, Gonzalez D, Mirjafary S, Birnbaum S, Razak KA, Gibson JR, Huber KM. Female specific dysfunction of sensory neocortical circuits in a mouse model of autism mediated by mGluR5 and Estrogen Receptor α. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.10.552857. [PMID: 37609208 PMCID: PMC10441407 DOI: 10.1101/2023.08.10.552857] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Autism manifests differently in males and females and the brain mechanisms that mediate these sex-dependent differences are unknown. Here, we demonstrate that deletion of the ASD-risk gene, Pten, in neocortical pyramidal neurons (NSE Pten KO) results in robust hyperexcitability of local neocortical circuits in female, but not male, mice, observed as prolonged, spontaneous persistent activity states (UP states). Circuit hyperexcitability in NSE Pten KO mice is mediated by enhanced and/or altered signaling of metabotropic glutamate receptor 5 (mGluR5) and estrogen receptor α (ERα) to ERK and protein synthesis selectively in Pten deleted female neurons. In support of this idea, Pten deleted Layer 5 cortical neurons have female-specific increases in mGluR5 and mGluR5-driven protein synthesis. In addition, mGluR5-ERα complexes are elevated in female cortex and genetic reduction of ERα in Pten KO cortical neurons rescues circuit excitability, protein synthesis and enlarged neurons selectively in females. Abnormal timing and hyperexcitability of neocortical circuits in female NSE Pten KO mice are associated with deficits in temporal processing of sensory stimuli and social behaviors as well as mGluR5-dependent seizures. Female-specific cortical hyperexcitability and mGluR5-dependent seizures are also observed in a human disease relevant mouse model, germline Pten +/- mice. Our results reveal molecular mechanisms by which sex and a high impact ASD-risk gene interact to affect brain function and behavior.
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3
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Huang L, Xiao W, Wang Y, Li J, Gong J, Tu E, Long L, Xiao B, Yan X, Wan L. Metabotropic glutamate receptors (mGluRs) in epileptogenesis: an update on abnormal mGluRs signaling and its therapeutic implications. Neural Regen Res 2024; 19:360-368. [PMID: 37488891 PMCID: PMC10503602 DOI: 10.4103/1673-5374.379018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 07/26/2023] Open
Abstract
Epilepsy is a neurological disorder characterized by high morbidity, high recurrence, and drug resistance. Enhanced signaling through the excitatory neurotransmitter glutamate is intricately associated with epilepsy. Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors activated by glutamate and are key regulators of neuronal and synaptic plasticity. Dysregulated mGluR signaling has been associated with various neurological disorders, and numerous studies have shown a close relationship between mGluRs expression/activity and the development of epilepsy. In this review, we first introduce the three groups of mGluRs and their associated signaling pathways. Then, we detail how these receptors influence epilepsy by describing the signaling cascades triggered by their activation and their neuroprotective or detrimental roles in epileptogenesis. In addition, strategies for pharmacological manipulation of these receptors during the treatment of epilepsy in experimental studies is also summarized. We hope that this review will provide a foundation for future studies on the development of mGluR-targeted antiepileptic drugs.
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Affiliation(s)
- Leyi Huang
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Wenjie Xiao
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Yan Wang
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Juan Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Jiaoe Gong
- Department of Neurology, Hunan Children’s Hospital, Changsha, Hunan Province, China
| | - Ewen Tu
- Department of Neurology, Brain Hospital of Hunan Province, Changsha, Hunan Province, China
| | - Lili Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Xiaoxin Yan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Lily Wan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
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4
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Winden KD, Pham TT, Teaney NA, Ruiz J, Chen R, Chen C, Sahin M. Increased degradation of FMRP contributes to neuronal hyperexcitability in tuberous sclerosis complex. Cell Rep 2023; 42:112838. [PMID: 37494191 PMCID: PMC10529098 DOI: 10.1016/j.celrep.2023.112838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/12/2023] [Accepted: 07/05/2023] [Indexed: 07/28/2023] Open
Abstract
Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental disorder, but new therapies have been impeded by a lack of understanding of the pathological mechanisms. Tuberous sclerosis complex (TSC) and fragile X syndrome are associated with alterations in the mechanistic target of rapamycin (mTOR) and fragile X messenger ribonucleoprotein 1 (FMRP), which have been implicated in the development of ASD. Previously, we observed that transcripts associated with FMRP were down-regulated in TSC2-deficient neurons. In this study, we find that FMRP turnover is dysregulated in TSC2-deficient rodent primary neurons and human induced pluripotent stem cell (iPSC)-derived neurons and is dependent on the E3 ubiquitin ligase anaphase-promoting complex. We also demonstrate that overexpression of FMRP can partially rescue hyperexcitability in TSC2-deficient iPSC-derived neurons. These data indicate that FMRP dysregulation represents an important pathological mechanism in the development of abnormal neuronal activity in TSC and illustrate a molecular convergence between these two neurogenetic disorders.
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Affiliation(s)
- Kellen D Winden
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Truc T Pham
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Nicole A Teaney
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Juan Ruiz
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ryan Chen
- Human Neuron Core, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Cidi Chen
- Human Neuron Core, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Mustafa Sahin
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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5
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Thomas SD, Jha NK, Ojha S, Sadek B. mTOR Signaling Disruption and Its Association with the Development of Autism Spectrum Disorder. Molecules 2023; 28:molecules28041889. [PMID: 36838876 PMCID: PMC9964164 DOI: 10.3390/molecules28041889] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/31/2023] [Accepted: 02/04/2023] [Indexed: 02/19/2023] Open
Abstract
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by impairments in social interaction and communication along with repetitive stereotypic behaviors. Currently, there are no specific biomarkers for diagnostic screening or treatments available for autistic patients. Numerous genetic disorders are associated with high prevalence of ASD, including tuberous sclerosis complex, phosphatase and tensin homolog, and fragile X syndrome. Preclinical investigations in animal models of these diseases have revealed irregularities in the PI3K/Akt/mTOR signaling pathway as well as ASD-related behavioral defects. Reversal of the downstream molecular irregularities, associated with mTOR hyperactivation, improved the behavioral deficits observed in the preclinical investigations. Plant bioactive molecules have shown beneficial pre-clinical evidence in ASD treatment by modulating the PI3K/Akt/mTOR pathway. In this review, we summarize the involvement of the PI3K/Akt/mTOR pathway as well as the genetic alterations of the pathway components and its critical impact on the development of the autism spectrum disorder. Mutations in negative regulators of mTORC1, such as TSC1, TSC2, and PTEN, result in ASD-like phenotypes through the disruption of the mTORC1-mediated signaling. We further discuss the various naturally occurring phytoconstituents that have been identified to be bioactive and modulate the pathway to prevent its disruption and contribute to beneficial therapeutic effects in ASD.
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Affiliation(s)
- Shilu Deepa Thomas
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering and Technology (SET), Sharda University, Greater Noida 201310, India
- School of Bioengineering & Biosciences, Lovely Professional University, Phagwara 144411, India
- Department of Biotechnology, School of Applied & Life Sciences (SALS), Uttaranchal University, Dehradun 248007, India
| | - Shreesh Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
| | - Bassem Sadek
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- Zayed Bin Sultan Center for Health Sciences, United Arab Emirates University, Al Ain P.O. Box 15551, United Arab Emirates
- Correspondence:
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Singh A, Hadjinicolaou A, Peters JM, Salussolia CL. Treatment-Resistant Epilepsy and Tuberous Sclerosis Complex: Treatment, Maintenance, and Future Directions. Neuropsychiatr Dis Treat 2023; 19:733-748. [PMID: 37041855 PMCID: PMC10083014 DOI: 10.2147/ndt.s347327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/22/2023] [Indexed: 04/13/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a neurogenetic disorder that affects multiple organ systems, including the heart, kidneys, eyes, skin, and central nervous system. The neurologic manifestations have the highest morbidity and mortality, in particular in children. Clinically, patients with TSC often present with new-onset seizures within the first year of life. TSC-associated epilepsy is often difficult to treat and refractory to multiple antiseizure medications. Refractory TSC-associated epilepsy is associated with increased risk of neurodevelopmental comorbidities, including developmental delay, intellectual disability, autism spectrum disorder, and attention hyperactivity disorder. An increasing body of research suggests that early, effective treatment of TSC-associated epilepsy during critical neurodevelopmental periods can potentially improve cognitive outcomes. Therefore, it is important to treat TSC-associated epilepsy aggressively, whether it be with pharmacological therapy, surgical intervention, and/or neuromodulation. This review discusses current and future pharmacological treatments for TSC-associated epilepsy, as well as the importance of early surgical evaluation for refractory epilepsy in children with TSC and consideration of neuromodulatory interventions in young adults.
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Affiliation(s)
- Avantika Singh
- Division of Epilepsy and Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Aristides Hadjinicolaou
- Division of Epilepsy and Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Jurriaan M Peters
- Division of Epilepsy and Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Catherine L Salussolia
- Division of Epilepsy and Neurophysiology, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, MA, USA
- Correspondence: Catherine L Salussolia, 3 Blackfan Circle, Center for Life Sciences 14060, Boston, MA, 02115, USA, Tel +617-355-7970, Email
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7
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Sánchez-Castillo C, Cuartero MI, Fernández-Rodrigo A, Briz V, López-García S, Jiménez-Sánchez R, López JA, Graupera M, Esteban JA. Functional specialization of different PI3K isoforms for the control of neuronal architecture, synaptic plasticity, and cognition. SCIENCE ADVANCES 2022; 8:eabq8109. [PMID: 36417513 PMCID: PMC9683729 DOI: 10.1126/sciadv.abq8109] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 10/25/2022] [Indexed: 06/16/2023]
Abstract
Neuronal connectivity and activity-dependent synaptic plasticity are fundamental properties that support brain function and cognitive performance. Phosphatidylinositol 3-kinase (PI3K) intracellular signaling controls multiple mechanisms mediating neuronal growth, synaptic structure, and plasticity. However, it is still unclear how these pleiotropic functions are integrated at molecular and cellular levels. To address this issue, we used neuron-specific virally delivered Cre expression to delete either p110α or p110β (the two major catalytic isoforms of type I PI3K) from the hippocampus of adult mice. We found that dendritic and postsynaptic structures are almost exclusively supported by p110α activity, whereas p110β controls neurotransmitter release and metabotropic glutamate receptor-dependent long-term depression at the presynaptic terminal. In addition to these separate functions, p110α and p110β jointly contribute to N-methyl-d-aspartate receptor-dependent postsynaptic long-term potentiation. This molecular and functional specialization is reflected in different proteomes controlled by each isoform and in distinct behavioral alterations for learning/memory and sociability in mice lacking p110α or p110β.
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Affiliation(s)
- Carla Sánchez-Castillo
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - María I. Cuartero
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Alba Fernández-Rodrigo
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Víctor Briz
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Sergio López-García
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Raquel Jiménez-Sánchez
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
| | - Juan A. López
- Proteomics Unit, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Instituto de Salud Carlos III, Madrid, Spain
| | - Mariona Graupera
- Endothelial Pathobiology and Microenviroment Group, Josep Carreras Leukaemia Research Institute (IJC), 08916 Badalona, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Cáncer (CIBERONC), Instituto de Salud Carlos III, Madrid, Spain
| | - José A. Esteban
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Madrid, Spain
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8
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Genetic ablation of metabotropic glutamate receptor 5 in rats results in an autism-like behavioral phenotype. PLoS One 2022; 17:e0275937. [PMCID: PMC9668160 DOI: 10.1371/journal.pone.0275937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in communication, and social skills, as well as repetitive and/or restrictive interests and behaviors. The severity of ASD varies from mild to severe, drastically interfering with the quality of life of affected individuals. The current occurrence of ASD in the United States is about 1 in 44 children. The precise pathophysiology of ASD is still unknown, but it is believed that ASD is heterogeneous and can arise due to genetic etiology. Although various genes have been implicated in predisposition to ASD, metabotropic glutamate receptor 5 (mGluR5) is one of the most common downstream targets, which may be involved in autism. mGluR5 signaling has been shown to play a crucial role in neurodevelopment and neural transmission making it a very attractive target for understanding the pathogenesis of ASD. In the present study, we determined the effect of genetic ablation of mGluR5 (Grm5) on an ASD-like phenotype using a rat model to better understand the role of mGluR5 signaling in behavior patterns and clinical manifestations of ASD. We observed that mGluR5 Ko rats exhibited exaggerated self-grooming and increased marble burying, as well as deficits in social novelty. Our results suggest that mGluR5 Ko rats demonstrate an ASD-like phenotype, specifically impaired social interaction as well as repetitive and anxiety-like behavior, which are correlates of behavior symptoms observed in individuals with ASD. The mGluR5 Ko rat model characterized in this study may be explored to understand the molecular mechanisms underlying ASD and for developing effective therapeutic modalities.
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9
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Matrisciano F, Locci V, Dong E, Nicoletti F, Guidotti A, Grayson DR. Altered Expression and In Vivo Activity of mGlu5 Variant a Receptors in the Striatum of BTBR Mice: Novel Insights Into the Pathophysiology of Adult Idiopathic Forms of Autism Spectrum Disorders. Curr Neuropharmacol 2022; 20:2354-2368. [PMID: 35139800 PMCID: PMC9890299 DOI: 10.2174/1567202619999220209112609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/27/2022] [Accepted: 01/31/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND mGlu5 metabotropic glutamate receptors are considered as candidate drug targets in the treatment of "monogenic" forms of autism spectrum disorders (ASD), such as Fragile- X syndrome (FXS). However, despite promising preclinical data, clinical trials using mGlu5 receptor antagonists to treat FXS showed no beneficial effects. OBJECTIVE Here, we studied the expression and function of mGlu5 receptors in the striatum of adult BTBR mice, which model idiopathic forms of ASD, and behavioral phenotype. METHODS Behavioral tests were associated with biochemistry analysis including qPCR and western blot for mRNA and protein expression. In vivo analysis of polyphosphoinositides hydrolysis was performed to study the mGlu5-mediated intracellular signaling in the striatum of adult BTBR mice under basal conditions and after MTEP exposure. RESULTS Expression of mGlu5 receptors and mGlu5 receptor-mediated polyphosphoinositides hydrolysis were considerably high in the striatum of BTBR mice, sensitive to MTEP treatment. Changes in the expression of genes encoding for proteins involved in excitatory and inhibitory neurotransmission and synaptic plasticity, including Fmr1, Dlg4, Shank3, Brd4, bdnf-exon IX, Mef2c, and Arc, GriA2, Glun1, Nr2A, and Grm1, Grm2, GriA1, and Gad1 were also found. Behaviorally, BTBR mice showed high repetitive stereotypical behaviors, including self-grooming and deficits in social interactions. Acute or repeated injections with MTEP reversed the stereotyped behavior and the social interaction deficit. Similar effects were observed with the NMDA receptor blockers MK-801 or ketamine. CONCLUSION These findings support a pivotal role of mGlu5 receptor abnormal expression and function in idiopathic ASD adult forms and unveil novel potential targets for therapy.
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Affiliation(s)
- Francesco Matrisciano
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois Chicago, Chicago, IL 60612, USA
| | - Valentina Locci
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois Chicago, Chicago, IL 60612, USA
| | - Erbo Dong
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois Chicago, Chicago, IL 60612, USA
- Center for Alcohol Research in Epigenetics Department of Psychiatry College of Medicine University of Illinois Chicago, Chicago, IL 60612, USA
| | - Ferdinando Nicoletti
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
- IRCCS Neuromed, Pozzilli, Italy
| | - Alessandro Guidotti
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois Chicago, Chicago, IL 60612, USA
- Center for Alcohol Research in Epigenetics Department of Psychiatry College of Medicine University of Illinois Chicago, Chicago, IL 60612, USA
| | - Dennis R. Grayson
- The Psychiatric Institute, Department of Psychiatry, College of Medicine, University of Illinois Chicago, Chicago, IL 60612, USA
- Center for Alcohol Research in Epigenetics Department of Psychiatry College of Medicine University of Illinois Chicago, Chicago, IL 60612, USA
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10
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Ojea Ramos S, Feld M, Fustiñana MS. Contributions of extracellular-signal regulated kinase 1/2 activity to the memory trace. Front Mol Neurosci 2022; 15:988790. [PMID: 36277495 PMCID: PMC9580372 DOI: 10.3389/fnmol.2022.988790] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 09/02/2022] [Indexed: 11/15/2022] Open
Abstract
The ability to learn from experience and consequently adapt our behavior is one of the most fundamental capacities enabled by complex and plastic nervous systems. Next to cellular and systems-level changes, learning and memory formation crucially depends on molecular signaling mechanisms. In particular, the extracellular-signal regulated kinase 1/2 (ERK), historically studied in the context of tumor growth and proliferation, has been shown to affect synaptic transmission, regulation of neuronal gene expression and protein synthesis leading to structural synaptic changes. However, to what extent the effects of ERK are specifically related to memory formation and stabilization, or merely the result of general neuronal activation, remains unknown. Here, we review the signals leading to ERK activation in the nervous system, the subcellular ERK targets associated with learning-related plasticity, and how neurons with activated ERK signaling may contribute to the formation of the memory trace.
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Affiliation(s)
- Santiago Ojea Ramos
- Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Mariana Feld
- Instituto de Fisiología, Biología Molecular y Neurociencias, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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11
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Raptor downregulation rescues neuronal phenotypes in mouse models of Tuberous Sclerosis Complex. Nat Commun 2022; 13:4665. [PMID: 35945201 PMCID: PMC9363483 DOI: 10.1038/s41467-022-31961-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 07/08/2022] [Indexed: 12/16/2022] Open
Abstract
Tuberous Sclerosis Complex (TSC) is a neurodevelopmental disorder caused by mutations in the TSC1 or TSC2 genes, which encode proteins that negatively regulate mTOR complex 1 (mTORC1) signaling. Current treatment strategies focus on mTOR inhibition with rapamycin and its derivatives. While effective at improving some aspects of TSC, chronic rapamycin inhibits both mTORC1 and mTORC2 and is associated with systemic side-effects. It is currently unknown which mTOR complex is most relevant for TSC-related brain phenotypes. Here we used genetic strategies to selectively reduce neuronal mTORC1 or mTORC2 activity in mouse models of TSC. We find that reduction of the mTORC1 component Raptor, but not the mTORC2 component Rictor, rebalanced mTOR signaling in Tsc1 knock-out neurons. Raptor reduction was sufficient to improve several TSC-related phenotypes including neuronal hypertrophy, macrocephaly, impaired myelination, network hyperactivity, and premature mortality. Raptor downregulation represents a promising potential therapeutic intervention for the neurological manifestations of TSC.
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12
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Koene LM, Niggl E, Wallaard I, Proietti-Onori M, Rotaru DC, Elgersma Y. Identifying the temporal electrophysiological and molecular changes that contribute to TSC-associated epileptogenesis. JCI Insight 2021; 6:e150120. [PMID: 34877936 PMCID: PMC8675202 DOI: 10.1172/jci.insight.150120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 10/27/2021] [Indexed: 11/17/2022] Open
Abstract
Tuberous sclerosis complex (TSC), caused by heterozygous mutations in TSC1 or TSC2, frequently results in intractable epilepsy. Here, we made use of an inducible Tsc1-knockout mouse model, allowing us to study electrophysiological and molecular changes of Tsc1-induced epileptogenesis over time. We recorded from pyramidal neurons in the hippocampus and somatosensory cortex (L2/L3) and combined this with an analysis of transcriptome changes during epileptogenesis. Deletion of Tsc1 resulted in hippocampus-specific changes in excitability and adaptation, which emerged before seizure onset and progressed over time. All phenotypes were rescued after early treatment with rapamycin, an mTOR inhibitor. Later in epileptogenesis, we observed a hippocampal increase of excitation-to-inhibition ratio. These cellular changes were accompanied by dramatic transcriptional changes, especially after seizure onset. Most of these changes were rescued upon rapamycin treatment. Of the genes encoding ion channels or belonging to the Gene Ontology term action potential, 27 were differentially expressed just before seizure onset, suggesting a potential driving role in epileptogenesis. Our data highlight the complex changes driving epileptogenesis in TSC, including the changed expression of multiple ion channels. Our study emphasizes inhibition of the TSC/mTOR signaling pathway as a promising therapeutic approach to target epilepsy in patients with TSC.
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Vasic V, Jones MSO, Haslinger D, Knaus LS, Schmeisser MJ, Novarino G, Chiocchetti AG. Translating the Role of mTOR- and RAS-Associated Signalopathies in Autism Spectrum Disorder: Models, Mechanisms and Treatment. Genes (Basel) 2021; 12:genes12111746. [PMID: 34828352 PMCID: PMC8624393 DOI: 10.3390/genes12111746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/25/2021] [Accepted: 10/28/2021] [Indexed: 12/23/2022] Open
Abstract
Mutations affecting mTOR or RAS signaling underlie defined syndromes (the so-called mTORopathies and RASopathies) with high risk for Autism Spectrum Disorder (ASD). These syndromes show a broad variety of somatic phenotypes including cancers, skin abnormalities, heart disease and facial dysmorphisms. Less well studied are the neuropsychiatric symptoms such as ASD. Here, we assess the relevance of these signalopathies in ASD reviewing genetic, human cell model, rodent studies and clinical trials. We conclude that signalopathies have an increased liability for ASD and that, in particular, ASD individuals with dysmorphic features and intellectual disability (ID) have a higher chance for disruptive mutations in RAS- and mTOR-related genes. Studies on rodent and human cell models confirm aberrant neuronal development as the underlying pathology. Human studies further suggest that multiple hits are necessary to induce the respective phenotypes. Recent clinical trials do only report improvements for comorbid conditions such as epilepsy or cancer but not for behavioral aspects. Animal models show that treatment during early development can rescue behavioral phenotypes. Taken together, we suggest investigating the differential roles of mTOR and RAS signaling in both human and rodent models, and to test drug treatment both during and after neuronal development in the available model systems.
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Affiliation(s)
- Verica Vasic
- Institute for Microscopic Anatomy and Neurobiology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany; (V.V.); (M.J.S.)
| | - Mattson S. O. Jones
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
| | - Denise Haslinger
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Lisa S. Knaus
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Michael J. Schmeisser
- Institute for Microscopic Anatomy and Neurobiology, University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany; (V.V.); (M.J.S.)
- Focus Program Translational Neurosciences (FTN), University Medical Center of the Johannes Gutenberg-University, 55131 Mainz, Germany
| | - Gaia Novarino
- Institute of Science and Technology (IST) Austria, 3400 Klosterneuburg, Austria; (L.S.K.); (G.N.)
| | - Andreas G. Chiocchetti
- Autism Therapy and Research Center of Excellence, Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt, 60528 Frankfurt am Main, Germany; (M.S.O.J.); (D.H.)
- Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, 60528 Frankfurt am Main, Germany
- Correspondence: ; Tel.: +49-69-6301-80658
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Sato A, Ikeda K. Genetic and Environmental Contributions to Autism Spectrum Disorder Through Mechanistic Target of Rapamycin. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2021; 2:95-105. [PMID: 36325164 PMCID: PMC9616270 DOI: 10.1016/j.bpsgos.2021.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 02/06/2023] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects an individual’s reciprocal social interaction and communication ability. Numerous genetic and environmental conditions are associated with ASD, including tuberous sclerosis complex, phosphatase and tensin homolog hamartoma tumor syndrome, fragile X syndrome, and neurofibromatosis 1. The pathogenic molecular mechanisms of these diseases are integrated into the hyperactivation of mTORC1 (mechanistic target of rapamycin complex 1). Rodent models of these diseases have shown high mTORC1 activity in the brain and ASD-related behavioral deficits, which were reversed by the mTORC1 inhibitor rapamycin. Environmental stress can also affect this signaling pathway. In utero exposure to valproate caused ASD in offspring and enhanced mTORC1 activity in the brain, which was sensitive to mTORC1 inhibition. mTORC1 is a signaling hub for diverse cellular functions, including protein synthesis, through the phosphorylation of its targets, such as ribosomal protein S6 kinases. Metabotropic glutamate receptor 5–mediated synaptic function is also affected by the dysregulation of mTORC1 activity, such as in fragile X syndrome and tuberous sclerosis complex. Reversing these downstream changes that are associated with mTORC1 activation normalizes behavioral defects in rodents. Despite abundant preclinical evidence, few clinical studies have investigated the treatment of ASD and cognitive deficits. Therapeutics other than mTORC1 inhibitors failed to show efficacy in fragile X syndrome and neurofibromatosis 1. mTORC1 inhibitors have been tested mainly in tuberous sclerosis complex, and their effects on ASD and neuropsychological deficits are promising. mTORC1 is a promising target for the pharmacological treatment of ASD associated with mTORC1 activation.
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Benthall KN, Cording KR, Agopyan-Miu AHCW, Wong CD, Chen EY, Bateup HS. Loss of Tsc1 from striatal direct pathway neurons impairs endocannabinoid-LTD and enhances motor routine learning. Cell Rep 2021; 36:109511. [PMID: 34380034 PMCID: PMC8404511 DOI: 10.1016/j.celrep.2021.109511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 05/28/2021] [Accepted: 07/21/2021] [Indexed: 02/08/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is a neurodevelopmental disorder that often presents with psychiatric conditions, including autism spectrum disorder (ASD). ASD is characterized by restricted, repetitive, and inflexible behaviors, which may result from abnormal activity in striatal circuits that mediate motor learning and action selection. To test whether altered striatal activity contributes to aberrant motor behaviors in the context of TSC, we conditionally deleted Tsc1 from direct or indirect pathway striatal projection neurons (dSPNs or iSPNs, respectively). We find that dSPN-specific loss of Tsc1 impairs endocannabinoid-mediated long-term depression (eCB-LTD) at cortico-dSPN synapses and strongly enhances corticostriatal synaptic drive, which is not observed in iSPNs. dSPN-Tsc1 KO, but not iSPN-Tsc1 KO, mice show enhanced motor learning, a phenotype observed in several mouse models of ASD. These findings demonstrate that dSPNs are particularly sensitive to Tsc1 loss and suggest that enhanced corticostriatal activation may contribute to altered motor behaviors in TSC.
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Affiliation(s)
- Katelyn N Benthall
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Katherine R Cording
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | - Corinna D Wong
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Emily Y Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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16
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Bassetti D, Luhmann HJ, Kirischuk S. Effects of Mutations in TSC Genes on Neurodevelopment and Synaptic Transmission. Int J Mol Sci 2021; 22:7273. [PMID: 34298906 PMCID: PMC8305053 DOI: 10.3390/ijms22147273] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 12/11/2022] Open
Abstract
Mutations in TSC1 or TSC2 genes are linked to alterations in neuronal function which ultimately lead to the development of a complex neurological phenotype. Here we review current research on the effects that reduction in TSC1 or TSC2 can produce on the developing neural network. A crucial feature of the disease pathophysiology appears to be an early deviation from typical neurodevelopment, in the form of structural abnormalities. Epileptic seizures are one of the primary early manifestation of the disease in the CNS, followed by intellectual deficits and autism spectrum disorders (ASD). Research using mouse models suggests that morphological brain alterations might arise from the interaction of different cellular types, and hyperexcitability in the early postnatal period might be transient. Moreover, the increased excitation-to-inhibition ratio might represent a transient compensatory adjustment to stabilize the developing network rather than a primary factor for the development of ASD symptoms. The inhomogeneous results suggest region-specificity as well as an evolving picture of functional alterations along development. Furthermore, ASD symptoms and epilepsy might originate from different but potentially overlapping mechanisms, which can explain recent observations obtained in patients. Potential treatment is determined not only by the type of medicament, but also by the time point of treatment.
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Affiliation(s)
- Davide Bassetti
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, 55128 Mainz, Germany; (H.J.L.); (S.K.)
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17
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Hien A, Molinaro G, Liu B, Huber KM, Richter JD. Ribosome profiling in mouse hippocampus: plasticity-induced regulation and bidirectional control by TSC2 and FMRP. Mol Autism 2020; 11:78. [PMID: 33054857 PMCID: PMC7556950 DOI: 10.1186/s13229-020-00384-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 09/23/2020] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Mutations in TSC2 are the most common cause of tuberous sclerosis (TSC), a disorder with a high incidence of autism and intellectual disability. TSC2 regulates mRNA translation required for group 1 metabotropic glutamate receptor-dependent synaptic long-term depression (mGluR-LTD) and behavior, but the identity of mRNAs responsive to mGluR-LTD signaling is largely unknown. METHODS We utilized Tsc2+/- mice as a mouse model of TSC and prepared hippocampal slices from these animals. We induced mGluR-LTD synaptic plasticity in slices and processed the samples for RNA-seq and ribosome profiling to identify differentially expressed genes in Tsc2+/- and following mGluR-LTD synaptic plasticity. RESULTS Ribosome profiling reveals that in Tsc2+/- mouse hippocampal slices, the expression of several mRNAs was dysregulated: terminal oligopyrimidine (TOP)-containing mRNAs decreased, while FMRP-binding targets increased. Remarkably, we observed the opposite changes of FMRP binding targets in Fmr1-/y hippocampi. In wild-type hippocampus, induction of mGluR-LTD caused rapid changes in the steady-state levels of hundreds of mRNAs, many of which are FMRP targets. Moreover, mGluR-LTD failed to promote phosphorylation of eukaryotic elongation factor 2 (eEF2) in TSC mice, and chemically mimicking phospho-eEF2 with low cycloheximide enhances mGluR-LTD in TSC mice. CONCLUSION These results suggest a molecular basis for bidirectional regulation of synaptic plasticity and behavior by TSC2 and FMRP. Our study also suggests that altered mGluR-regulated translation elongation contributes to impaired synaptic plasticity in Tsc2+/- mice.
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Affiliation(s)
- Annie Hien
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
- Medical Scientist Training Program, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Gemma Molinaro
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Botao Liu
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Kimberly M Huber
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Joel D Richter
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA.
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18
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Sex-Selective Effects on Behavior in a Mouse Model of Tuberous Sclerosis Complex. eNeuro 2020; 7:ENEURO.0379-19.2020. [PMID: 32303566 PMCID: PMC7196723 DOI: 10.1523/eneuro.0379-19.2020] [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: 09/20/2019] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 01/19/2023] Open
Abstract
Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder that is caused by a mutation in either TSC1 or TSC2 TSC affects multiple systems of the body, and patients with TSC display a range of neurologic and behavioral manifestations including seizures, intellectual disability, autism spectrum disorders, attention deficit hyperactivity disorder, anxiety, and mood disorders. Whereas behavioral phenotypes of many mouse models have been studied, the effects of sex have, for the most part, not been explored. We studied adult male and female Tsc2 heterozygous and control mice to investigate the influence of sex and genotype on behavior. On a test of social preference, Tsc2 heterozygous mice, regardless of sex, demonstrated lower preference for the stranger mouse than control mice. In the open field, Tsc2 heterozygous males and control females habituated to the open field with decreasing anxiety-like behavior over time, whereas Tsc2 heterozygous females did not show habituation to the open field environment. We did not find any statistically significant effects of genotype on open field activity, learning and memory or motor function. Our results highlight phenotype differences in Tsc2 heterozygous mice, some of which are influenced by sex. A consideration of how sex influences the behavioral phenotypes of TSC is critical to develop a more complete understanding of the disorder and better target future pharmacological treatments.
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19
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Wu HF, Lu TY, Chu MC, Chen PS, Lee CW, Lin HC. Targeting the inhibition of fatty acid amide hydrolase ameliorate the endocannabinoid-mediated synaptic dysfunction in a valproic acid-induced rat model of Autism. Neuropharmacology 2020; 162:107736. [DOI: 10.1016/j.neuropharm.2019.107736] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 08/02/2019] [Accepted: 08/05/2019] [Indexed: 10/26/2022]
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20
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Kosillo P, Doig NM, Ahmed KM, Agopyan-Miu AHCW, Wong CD, Conyers L, Threlfell S, Magill PJ, Bateup HS. Tsc1-mTORC1 signaling controls striatal dopamine release and cognitive flexibility. Nat Commun 2019; 10:5426. [PMID: 31780742 PMCID: PMC6882901 DOI: 10.1038/s41467-019-13396-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 11/07/2019] [Indexed: 11/13/2022] Open
Abstract
Tuberous Sclerosis Complex (TSC) is a neurodevelopmental disorder caused by mutations in TSC1 or TSC2, which encode proteins that negatively regulate mTOR complex 1 (mTORC1). TSC is associated with significant cognitive, psychiatric, and behavioral problems, collectively termed TSC-Associated Neuropsychiatric Disorders (TAND), and the cell types responsible for these manifestations are largely unknown. Here we use cell type-specific Tsc1 deletion to test whether dopamine neurons, which modulate cognitive, motivational, and affective behaviors, are involved in TAND. We show that loss of Tsc1 and constitutive activation of mTORC1 in dopamine neurons causes somatodendritic hypertrophy, reduces intrinsic excitability, alters axon terminal structure, and impairs striatal dopamine release. These perturbations lead to a selective deficit in cognitive flexibility, preventable by genetic reduction of the mTOR-binding protein Raptor. Our results establish a critical role for Tsc1-mTORC1 signaling in setting the functional properties of dopamine neurons, and indicate that dopaminergic dysfunction may contribute to cognitive inflexibility in TSC.
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Affiliation(s)
- Polina Kosillo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Natalie M Doig
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, OX1 3TH, UK
| | - Kamran M Ahmed
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | | | - Corinna D Wong
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Lisa Conyers
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, OX1 3TH, UK
| | - Sarah Threlfell
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
- Oxford Parkinson's Disease Centre, University of Oxford, Oxford, OX1 3QX, UK
| | - Peter J Magill
- Medical Research Council Brain Network Dynamics Unit, University of Oxford, Oxford, OX1 3TH, UK
- Oxford Parkinson's Disease Centre, University of Oxford, Oxford, OX1 3QX, UK
| | - Helen S Bateup
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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21
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Histone deacetylase inhibitors restore normal hippocampal synaptic plasticity and seizure threshold in a mouse model of Tuberous Sclerosis Complex. Sci Rep 2019; 9:5266. [PMID: 30918308 PMCID: PMC6437206 DOI: 10.1038/s41598-019-41744-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/15/2019] [Indexed: 01/02/2023] Open
Abstract
Abnormal synaptic plasticity has been implicated in several neurological disorders including epilepsy, dementia and Autism Spectrum Disorder (ASD). Tuberous Sclerosis Complex (TSC) is an autosomal dominant genetic disorder that manifests with seizures, autism, and cognitive deficits. The abnormal intracellular signaling underlying TSC has been the focus of many studies. However, nothing is known about the role of histone modifications in contributing to the neurological manifestations in TSC. Dynamic regulation of chromatin structure via post translational modification of histone tails has been implicated in learning, memory and synaptic plasticity. Histone acetylation and associated gene activation plays a key role in plasticity and so we asked whether histone acetylation might be dysregulated in TSC. In this study, we report a general reduction in hippocampal histone H3 acetylation levels in a mouse model of TSC2. Pharmacological inhibition of Histone Deacetylase (HDAC) activity restores histone H3 acetylation levels and ameliorates the aberrant plasticity in TSC2+/− mice. We describe a novel seizure phenotype in TSC2+/− mice that is also normalized with HDAC inhibitors (HDACis). The results from this study suggest an unanticipated role for chromatin modification in TSC and may inform novel therapeutic strategies for TSC patients.
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22
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Brown EA, Lautz JD, Davis TR, Gniffke EP, VanSchoiack AAW, Neier SC, Tashbook N, Nicolini C, Fahnestock M, Schrum AG, Smith SEP. Clustering the autisms using glutamate synapse protein interaction networks from cortical and hippocampal tissue of seven mouse models. Mol Autism 2018; 9:48. [PMID: 30237867 PMCID: PMC6139139 DOI: 10.1186/s13229-018-0229-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 08/20/2018] [Indexed: 12/22/2022] Open
Abstract
Background Autism spectrum disorders (ASDs) are a heterogeneous group of behaviorally defined disorders and are associated with hundreds of rare genetic mutations and several environmental risk factors. Mouse models of specific risk factors have been successful in identifying molecular mechanisms associated with a given factor. However, comparisons among different models to elucidate underlying common pathways or to define clusters of biologically relevant disease subtypes have been complicated by different methodological approaches or different brain regions examined by the labs that developed each model. Here, we use a novel proteomic technique, quantitative multiplex co-immunoprecipitation or QMI, to make a series of identical measurements of a synaptic protein interaction network in seven different animal models. We aim to identify molecular disruptions that are common to multiple models. Methods QMI was performed on 92 hippocampal and cortical samples taken from seven mouse models of ASD: Shank3B, Shank3Δex4-9, Ube3a2xTG, TSC2, FMR1, and CNTNAP2 mutants, as well as E12.5 VPA (maternal valproic acid injection on day 12.5 post-conception). The QMI panel targeted a network of 16 interacting, ASD-linked, synaptic proteins, probing 240 potential co-associations. A custom non-parametric statistical test was used to call significant differences between ASD models and littermate controls, and Hierarchical Clustering by Principal Components was used to cluster the models using mean log2 fold change values. Results Each model displayed a unique set of disrupted interactions, but some interactions were disrupted in multiple models. These tended to be interactions that are known to change with synaptic activity. Clustering revealed potential relationships among models and suggested deficits in AKT signaling in Ube3a2xTG mice, which were confirmed by phospho-western blots. Conclusions These data highlight the great heterogeneity among models, but suggest that high-dimensional measures of a synaptic protein network may allow differentiation of subtypes of ASD with shared molecular pathology.
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Affiliation(s)
- Emily A Brown
- 1Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA USA
| | - Jonathan D Lautz
- 1Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA USA
| | - Tessa R Davis
- 2Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN USA.,3Present address: Department of Biomedical Engineering, UT Austin, Austin, TX USA
| | - Edward P Gniffke
- 1Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA USA
| | - Alison A W VanSchoiack
- 1Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA USA.,Present address: Nanostring, Seattle, WA USA
| | - Steven C Neier
- 2Department of Immunology, Mayo Clinic College of Medicine, Rochester, MN USA.,5Present address: Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA USA.,6Present address: Department of Medicine, Harvard Medical School, Boston, MA USA.,7Present address: Broad Institute of Harvard and MIT, Cambridge, MA USA
| | - Noah Tashbook
- 1Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA USA
| | - Chiara Nicolini
- 8Department of Psychiatry & Behavioural Neurosciences, McMaster University, Hamilton, ON Canada
| | - Margaret Fahnestock
- 8Department of Psychiatry & Behavioural Neurosciences, McMaster University, Hamilton, ON Canada
| | - Adam G Schrum
- 9Departments of Molecular Microbiology & Immunology, Surgery and Bioengineering, University of Missouri, Columbia, MO USA
| | - Stephen E P Smith
- 1Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA USA.,10Department of Pediatrics and Graduate Program in Neuroscience, University of Washington, Seattle, WA USA
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mGluR5 Modulation of Behavioral and Epileptic Phenotypes in a Mouse Model of Tuberous Sclerosis Complex. Neuropsychopharmacology 2018; 43:1457-1465. [PMID: 29206810 PMCID: PMC5916364 DOI: 10.1038/npp.2017.295] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/03/2017] [Accepted: 11/28/2017] [Indexed: 12/13/2022]
Abstract
Drugs targeting metabotropic glutamate receptor 5 (mGluR5) have therapeutic potential in autism spectrum disorders (ASD), including tuberous sclerosis complex (TSC). The question whether inhibition or potentiation of mGluR5 could be beneficial depends, among other factors, on the specific indication. To facilitate the development of mGluR5 treatment strategies, we tested the therapeutic utility of mGluR5 negative and positive allosteric modulators (an mGluR5 NAM and PAM) for TSC, using a mutant mouse model with neuronal loss of Tsc2 that demonstrates disease-related phenotypes, including behavioral symptoms of ASD and epilepsy. This model uniquely enables the in vivo characterization and rescue of the electrographic seizures associated with TSC. We demonstrate that inhibition of mGluR5 corrects hyperactivity, seizures, and elevated de novo synaptic protein synthesis. Conversely, positive allosteric modulation of mGluR5 results in the exacerbation of hyperactivity and epileptic phenotypes. The data suggest a meaningful therapeutic potential for mGluR5 NAMs in TSC, which warrants clinical exploration and the continued development of mGluR5 therapies.
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24
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Levenga J, Wong H, Milstead RA, Keller BN, LaPlante LE, Hoeffer CA. AKT isoforms have distinct hippocampal expression and roles in synaptic plasticity. eLife 2017; 6:30640. [PMID: 29173281 PMCID: PMC5722612 DOI: 10.7554/elife.30640] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/21/2017] [Indexed: 12/20/2022] Open
Abstract
AKT is a kinase regulating numerous cellular processes in the brain, and mutations in AKT are known to affect brain function. AKT is indirectly implicated in synaptic plasticity, but its direct role has not been studied. Moreover, three highly related AKT isoforms are expressed in the brain, but their individual roles are poorly understood. We find in Mus musculus, each AKT isoform has a unique expression pattern in the hippocampus, with AKT1 and AKT3 primarily in neurons but displaying local differences, while AKT2 is in astrocytes. We also find isoform-specific roles for AKT in multiple paradigms of hippocampal synaptic plasticity in area CA1. AKT1, but not AKT2 or AKT3, is required for L-LTP through regulating activity-induced protein synthesis. Interestingly, AKT activity inhibits mGluR-LTD, with overlapping functions for AKT1 and AKT3. In summary, our studies identify distinct expression patterns and roles in synaptic plasticity for AKT isoforms in the hippocampus.
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Affiliation(s)
- Josien Levenga
- Institute for Behavioral Genetics, University of Colorado-Boulder, Boulder, United States.,Linda Crnic Institute, Aurora, United States
| | - Helen Wong
- Institute for Behavioral Genetics, University of Colorado-Boulder, Boulder, United States
| | - Ryan A Milstead
- Department of Integrative Physiology, University of Colorado-Boulder, Boulder, United States
| | - Bailey N Keller
- Institute for Behavioral Genetics, University of Colorado-Boulder, Boulder, United States
| | - Lauren E LaPlante
- Institute for Behavioral Genetics, University of Colorado-Boulder, Boulder, United States
| | - Charles A Hoeffer
- Institute for Behavioral Genetics, University of Colorado-Boulder, Boulder, United States.,Linda Crnic Institute, Aurora, United States.,Department of Integrative Physiology, University of Colorado-Boulder, Boulder, United States
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The mTOR signalling cascade: paving new roads to cure neurological disease. Nat Rev Neurol 2016; 12:379-92. [PMID: 27340022 DOI: 10.1038/nrneurol.2016.81] [Citation(s) in RCA: 262] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Defining the multiple roles of the mechanistic (formerly 'mammalian') target of rapamycin (mTOR) signalling pathway in neurological diseases has been an exciting and rapidly evolving story of bench-to-bedside translational research that has spanned gene mutation discovery, functional experimental validation of mutations, pharmacological pathway manipulation, and clinical trials. Alterations in the dual contributions of mTOR - regulation of cell growth and proliferation, as well as autophagy and cell death - have been found in developmental brain malformations, epilepsy, autism and intellectual disability, hypoxic-ischaemic and traumatic brain injuries, brain tumours, and neurodegenerative disorders. mTOR integrates a variety of cues, such as growth factor levels, oxygen levels, and nutrient and energy availability, to regulate protein synthesis and cell growth. In line with the positioning of mTOR as a pivotal cell signalling node, altered mTOR activation has been associated with a group of phenotypically diverse neurological disorders. To understand how altered mTOR signalling leads to such divergent phenotypes, we need insight into the differential effects of enhanced or diminished mTOR activation, the developmental context of these changes, and the cell type affected by altered signalling. A particularly exciting feature of the tale of mTOR discovery is that pharmacological mTOR inhibitors have shown clinical benefits in some neurological disorders, such as tuberous sclerosis complex, and are being considered for clinical trials in epilepsy, autism, dementia, traumatic brain injury, and stroke.
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Sato A. mTOR, a Potential Target to Treat Autism Spectrum Disorder. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2016; 15:533-43. [PMID: 27071790 PMCID: PMC5070418 DOI: 10.2174/1871527315666160413120638] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/11/2015] [Accepted: 12/18/2015] [Indexed: 12/22/2022]
Abstract
Mammalian target of rapamycin (mTOR) is a key regulator in various cellular processes, including cell growth, gene expression, and synaptic functions. Autism spectrum disorder (ASD) is frequently accompanied by monogenic disorders, such as tuberous sclerosis complex, phosphatase and tensin homolog tumor hamartoma syndrome, neurofibromatosis 1, and fragile X syndrome, in which mTOR is hyperactive. Mutations in the genes involved in the mTOR-mediated signaling pathway have been identified in some cases of syndromic ASD. Evidences indicate a pathogenic role for hyperactive mTOR-mediated signaling in ASD associated with these monogenic disorders, and mTOR inhibitors are a potential pharmacotherapy for ASD. Abnormal synaptic transmission through metabotropic glutamate receptor 5 may underlie in a part of ASD associated with hyperactive mTOR-mediated signaling. In this review, the relationship between mTOR and ASD is discussed.
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Affiliation(s)
- Atsushi Sato
- Department of Pediatrics, The University of Tokyo Hospital, Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113- 8655, Japan.
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Dulla CG. More Than mTOR? Novel Roles for MEK-ERK1/2 and FLNA in Tuberous Sclerosis Complex. Epilepsy Curr 2015; 15:221-2. [PMID: 26316874 PMCID: PMC4532239 DOI: 10.5698/1535-7511-15.4.221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Kotajima-Murakami H, Sato A, Ikeda K. [Pathology and treatment of autism spectrum disorders]. Nihon Yakurigaku Zasshi 2015; 145:193-200. [PMID: 25864830 DOI: 10.1254/fpj.145.193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Zantomio D, Chana G, Laskaris L, Testa R, Everall I, Pantelis C, Skafidas E. Convergent evidence for mGluR5 in synaptic and neuroinflammatory pathways implicated in ASD. Neurosci Biobehav Rev 2015; 52:172-7. [PMID: 25704074 DOI: 10.1016/j.neubiorev.2015.02.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/25/2015] [Accepted: 02/07/2015] [Indexed: 01/05/2023]
Abstract
The pathogenesis of Autism Spectrum Disorder (ASD), a serious neurodevelopmental disorder, is poorly understood. We review evidence for alterations in glutamatergic signalling in the aetiology of ASD, with a focus on the metabotropic glutamate receptor-5 (mGluR5). mGluR5 signalling is important for synapse formation, neuroplasticity and long term potentiation as well as neuroprotection and has been shown to have a regulatory role in neuroinflammation. Evidence for neuroinflammation in ASD is supported by increase in pro-inflammatory cytokines in the blood and cerebrospinal fluid (CSF) and increased number and activation of microglia in postmortem dorsolateral prefrontal cortex (DLPFC). mGlur5 signalling has also been shown to downregulate microglial activation. Therefore, we focus on mGluR5 as a potential unifying explanation for synapse alteration and neuroinflammation seen in ASD. Data from mGluR5 knockout mouse models, and syndromic and non syndromic forms of ASD are discussed in relation to how alterations in mGluR5 are associated with ASD symptoms. This review supports altered mGluR5 functioning as a convergent point in ASD pathogenesis and indicates more research is warranted into mGluR5 as a potential therapeutic target.
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Affiliation(s)
- Daniela Zantomio
- Department of Haematology, Austin Health, Heidelberg, VIC, Australia; Centre for Neural Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Gursharan Chana
- Centre for Neural Engineering, The University of Melbourne, Parkville, Victoria, Australia; Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia; The Florey Institute of Neuroscience and Mental Health, Australia
| | - Liliana Laskaris
- Centre for Neural Engineering, The University of Melbourne, Parkville, Victoria, Australia; Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia
| | - Renee Testa
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Parkville, Victoria, Australia; Department of Psychology, Monash University, Clayton, Vic, Australia
| | - Ian Everall
- Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia; The Florey Institute of Neuroscience and Mental Health, Australia
| | - Christos Pantelis
- Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia; Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne & Melbourne Health, Parkville, Victoria, Australia; The Florey Institute of Neuroscience and Mental Health, Australia
| | - Efstratios Skafidas
- Centre for Neural Engineering, The University of Melbourne, Parkville, Victoria, Australia; Department of Psychiatry, The University of Melbourne, Parkville, Victoria, Australia; The Florey Institute of Neuroscience and Mental Health, Australia; Centre for Integrative Brain Function, Australia.
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Baudouin SJ. Heterogeneity and convergence: the synaptic pathophysiology of autism. Eur J Neurosci 2014; 39:1107-13. [PMID: 24712990 DOI: 10.1111/ejn.12498] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/24/2013] [Accepted: 01/02/2014] [Indexed: 11/30/2022]
Abstract
Autism is a developmental disorder characterised by a high heterogeneity of clinical diagnoses and genetic associations. This heterogeneity is a challenge for the identification of the pathophysiology of the disease and for the development of new therapeutic strategies. New conceptual approaches are being used to try to challenge this complexity and gene cluster analysis studies suggest that the pathophysiology of autism is associated with a dysregulation of specific cellular mechanisms. This review will present the experimental evidence for a convergence of synaptic pathophysiology between syndromic and non-syndromic forms of autism, grouped under the generic term of autism spectrum disorders. In particular I will highlight the results from genetic mouse models identifying a convergence of dysregulation of the synaptic type I metabotropic glutamate receptor pathway in mouse models for autism spectrum disorders. These results help to build a new conceptual framework for the study of the synaptic phenotype of autism, which is important for the identification of new therapeutic strategies.
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Affiliation(s)
- Stéphane J Baudouin
- Biozentrum of the University of Basel, Basel, Switzerland; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
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31
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Modulation of the extinction of fear learning. Brain Res Bull 2014; 105:61-9. [DOI: 10.1016/j.brainresbull.2014.04.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 11/19/2022]
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Bartley CM, O’Keefe RA, Bordey A. FMRP S499 is phosphorylated independent of mTORC1-S6K1 activity. PLoS One 2014; 9:e96956. [PMID: 24806451 PMCID: PMC4013076 DOI: 10.1371/journal.pone.0096956] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 04/08/2014] [Indexed: 11/18/2022] Open
Abstract
Hyperactive mammalian target of rapamycin (mTOR) is associated with cognitive deficits in several neurological disorders including tuberous sclerosis complex (TSC). The phosphorylation of the mRNA-binding protein FMRP reportedly depends on mTOR complex 1 (mTORC1) activity via p70 S6 kinase 1 (S6K1). Because this phosphorylation is thought to regulate the translation of messages important for synaptic plasticity, we explored whether FMRP phosphorylation of the S6K1-dependent residue (S499) is altered in TSC and states of dysregulated TSC-mTORC1 signaling. Surprisingly, we found that FMRP S499 phosphorylation was unchanged in heterozygous and conditional Tsc1 knockout mice despite significantly elevated mTORC1-S6K1 activity. Neither up- nor down-regulation of the mTORC1-S6K1 axis in vivo or in vitro had any effect on phospho-FMRP S499 levels. In addition, FMRP S499 phosphorylation was unaltered in S6K1-knockout mice. Collectively, these data strongly suggest that FMRP S499 phosphorylation is independent of mTORC1-S6K1 activity and is not altered in TSC.
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Affiliation(s)
- Christopher M. Bartley
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Medical Scientist Training Program, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Rachel A. O’Keefe
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Angélique Bordey
- Departments of Neurosurgery, and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Bernard PB, Castano AM, Bayer KU, Benke TA. Necessary, but not sufficient: insights into the mechanisms of mGluR mediated long-term depression from a rat model of early life seizures. Neuropharmacology 2014; 84:1-12. [PMID: 24780380 DOI: 10.1016/j.neuropharm.2014.04.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/28/2014] [Accepted: 04/14/2014] [Indexed: 01/25/2023]
Abstract
Using the rat model of early life seizures (ELS), which has exaggerated mGluR mediated long-term depression of synaptic strength (mGluR-LTD) in adulthood, we probed the signaling cascades underlying mGluR-LTD induction. Several inhibitors completely blocked mGluR-LTD in control but not in ELS rats: the proteasome, the mammalian target of rapamycin (mTOR), S6 kinase (S6K), or L-type voltage-gated calcium channels (L-type VGCC). Inhibition of the Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) resulted in a near complete block of mGluR-LTD in control rats and a slight reduction of mGluR-LTD in ELS rats. "Autonomous" CaMKII was found to be upregulated in ELS rats, while elevated S6K activity, which is stimulated by mTOR, was described previously. Thus, modulation of each of these factors was necessary for mGluR-LTD induction in control rats, but even their combined, permanent activation in the ELS rats was not sufficient to individually support mGluR-LTD induction following ELS. This implies that while these factors may act sequentially in controls to mediate mGluR-LTD, this is no longer the case after ELS. In contrast, activated ERK was found to be significantly down-regulated in ELS rats. Inhibition of MEK/ERK activation in control rats elevated mGluR-LTD to the exaggerated levels seen in ELS rats. Together, these results elucidate both the mechanisms that persistently enhance mGluR-LTD after ELS and the mechanisms underlying normal mGluR-LTD by providing evidence for multiple, convergent pathways that mediate mGluR-LTD induction. With our prior work, this ties these signaling cascades to the ELS behavioral phenotype that includes abnormal working memory, fear conditioning and socialization.
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Affiliation(s)
- Paul B Bernard
- Department of Pediatrics, University of Colorado, School of Medicine, CO, USA
| | - Anna M Castano
- Department of Pediatrics, University of Colorado, School of Medicine, CO, USA
| | - K Ulrich Bayer
- Neuroscience Graduate Program, University of Colorado, School of Medicine, CO, USA; Department of Pharmacology, University of Colorado, School of Medicine, CO, USA
| | - Tim A Benke
- Department of Pediatrics, University of Colorado, School of Medicine, CO, USA; Neuroscience Graduate Program, University of Colorado, School of Medicine, CO, USA; Department of Neurology, University of Colorado, School of Medicine, CO, USA; Department of Pharmacology, University of Colorado, School of Medicine, CO, USA; Department of Otolaryngology, University of Colorado, School of Medicine, CO, USA.
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