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Dhaliwal NK, Weng OY, Dong X, Bhattacharya A, Ahmed M, Nishimura H, Choi WWY, Aggarwal A, Luikart BW, Shu Q, Li X, Wilson MD, Moffat J, Wang LY, Muffat J, Li Y. Synergistic hyperactivation of both mTORC1 and mTORC2 underlies the neural abnormalities of PTEN-deficient human neurons and cortical organoids. Cell Rep 2024; 43:114173. [PMID: 38700984 DOI: 10.1016/j.celrep.2024.114173] [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: 09/22/2023] [Revised: 03/20/2024] [Accepted: 04/16/2024] [Indexed: 05/05/2024] Open
Abstract
Mutations in the phosphatase and tensin homolog (PTEN) gene are associated with severe neurodevelopmental disorders. Loss of PTEN leads to hyperactivation of the mechanistic target of rapamycin (mTOR), which functions in two distinct protein complexes, mTORC1 and mTORC2. The downstream signaling mechanisms that contribute to PTEN mutant phenotypes are not well delineated. Here, we show that pluripotent stem cell-derived PTEN mutant human neurons, neural precursors, and cortical organoids recapitulate disease-relevant phenotypes, including hypertrophy, electrical hyperactivity, enhanced proliferation, and structural overgrowth. PTEN loss leads to simultaneous hyperactivation of mTORC1 and mTORC2. We dissect the contribution of mTORC1 and mTORC2 by generating double mutants of PTEN and RPTOR or RICTOR, respectively. Our results reveal that the synergistic hyperactivation of both mTORC1 and mTORC2 is essential for the PTEN mutant human neural phenotypes. Together, our findings provide insights into the molecular mechanisms that underlie PTEN-related neural disorders and highlight novel therapeutic targets.
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Affiliation(s)
- Navroop K Dhaliwal
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Octavia Yifang Weng
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Xiaoxue Dong
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; The Children's Hospital, National Clinical Research Center for Child Health, School of Medicine, Zhejiang University, Hangzhou 310052, China; The Institute of Translational Medicine, School of Medicine, Zhejiang University, Hangzhou 310029, China
| | - Afrin Bhattacharya
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Mai Ahmed
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Haruka Nishimura
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Wendy W Y Choi
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Aditi Aggarwal
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Bryan W Luikart
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Qiang Shu
- The Children's Hospital, National Clinical Research Center for Child Health, School of Medicine, Zhejiang University, Hangzhou 310052, China
| | - Xuekun Li
- The Children's Hospital, National Clinical Research Center for Child Health, School of Medicine, Zhejiang University, Hangzhou 310052, China; The Institute of Translational Medicine, School of Medicine, Zhejiang University, Hangzhou 310029, China
| | - Michael D Wilson
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Jason Moffat
- Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada
| | - Lu-Yang Wang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Julien Muffat
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Yun Li
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
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2
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Guo D, Han L, Godale CM, Rensing NR, Danzer SC, Wong M. A role of dentate gyrus mechanistic target of rapamycin activation in epileptogenesis in a mouse model of posttraumatic epilepsy. Epilepsia 2024. [PMID: 38761065 DOI: 10.1111/epi.18011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 04/30/2024] [Accepted: 04/30/2024] [Indexed: 05/20/2024]
Abstract
OBJECTIVE The mechanistic target of rapamycin (mTOR) pathway has been implicated in promoting epileptogenesis in animal models of acquired epilepsy, such as posttraumatic epilepsy (PTE) following traumatic brain injury (TBI). However, the specific anatomical regions and neuronal populations mediating mTOR's role in epileptogenesis are not well defined. In this study, we tested the hypothesis that mTOR activation in dentate gyrus granule cells promotes neuronal death, mossy fiber sprouting, and PTE in the controlled cortical impact (CCI) model of TBI. METHODS An adeno-associated virus (AAV)-Cre viral vector was injected into the hippocampus of Rptorflox/flox (regulatory-associated protein of mTOR) mutant mice to inhibit mTOR activation in dentate gyrus granule cells. Four weeks after AAV-Cre or AAV-vehicle injection, mice underwent CCI injury and were subsequently assessed for mTOR pathway activation by Western blotting, neuronal death, and mossy fiber sprouting by immunopathological analysis, and posttraumatic seizures by video-electroencephalographic monitoring. RESULTS AAV-Cre injection primarily affected the dentate gyrus and inhibited hippocampal mTOR activation following CCI injury. AAV-Cre-injected mice had reduced neuronal death in dentate gyrus detected by Fluoro-Jade B staining and decreased mossy fiber sprouting by ZnT3 immunostaining. Finally, AAV-Cre-injected mice exhibited a decrease in incidence of PTE. SIGNIFICANCE mTOR pathway activation in dentate gyrus granule cells may at least partly mediate pathological abnormalities and epileptogenesis in models of TBI and PTE. Targeted modulation of mTOR activity in this hippocampal network may represent a focused therapeutic approach for antiepileptogenesis and prevention of PTE.
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Affiliation(s)
- Dongjun Guo
- Department of Neurology and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Lirong Han
- Department of Neurology and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Christin M Godale
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Nicholas R Rensing
- Department of Neurology and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Steve C Danzer
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Michael Wong
- Department of Neurology and Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, USA
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3
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Tucker SK, Ghosal R, Swartz ME, Zhang S, Eberhart JK. Zebrafish raptor mutation inhibits the activity of mTORC1, inducing craniofacial defects due to autophagy-induced neural crest cell death. Development 2024; 151:dev202216. [PMID: 38512806 PMCID: PMC11006402 DOI: 10.1242/dev.202216] [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: 07/25/2023] [Accepted: 01/26/2024] [Indexed: 03/23/2024]
Abstract
The mechanistic target of rapamycin (mTOR) coordinates metabolism and cell growth with environmental inputs. mTOR forms two functional complexes: mTORC1 and mTORC2. Proper development requires both complexes but mTORC1 has unique roles in numerous cellular processes, including cell growth, survival and autophagy. Here, we investigate the function of mTORC1 in craniofacial development. We created a zebrafish raptor mutant via CRISPR/Cas9, to specifically disrupt mTORC1. The entire craniofacial skeleton and eyes were reduced in size in mutants; however, overall body length and developmental timing were not affected. The craniofacial phenotype associates with decreased chondrocyte size and increased neural crest cell death. We found that autophagy is elevated in raptor mutants. Chemical inhibition of autophagy reduced cell death and improved craniofacial phenotypes in raptor mutants. Genetic inhibition of autophagy, via mutation of the autophagy gene atg7, improved facial phenotypes in atg7;raptor double mutants, relative to raptor single mutants. We conclude that finely regulated levels of autophagy, via mTORC1, are crucial for craniofacial development.
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Affiliation(s)
- Scott K. Tucker
- Department of Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research and Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
| | - Ritika Ghosal
- Department of Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research and Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
| | - Mary E. Swartz
- Department of Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research and Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
| | - Stephanie Zhang
- Department of Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research and Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
| | - Johann K. Eberhart
- Department of Molecular Biosciences, Waggoner Center for Alcohol and Addiction Research and Institute for Neuroscience, University of Texas, Austin, TX 78712, USA
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4
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Cullen ER, Safari M, Mittelstadt I, Weston MC. Hyperactivity of mTORC1- and mTORC2-dependent signaling mediates epilepsy downstream of somatic PTEN loss. eLife 2024; 12:RP91323. [PMID: 38446016 PMCID: PMC10942640 DOI: 10.7554/elife.91323] [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] [Indexed: 03/07/2024] Open
Abstract
Gene variants that hyperactivate PI3K-mTOR signaling in the brain lead to epilepsy and cortical malformations in humans. Some gene variants associated with these pathologies only hyperactivate mTORC1, but others, such as PTEN, PIK3CA, and AKT, hyperactivate both mTORC1- and mTORC2-dependent signaling. Previous work established a key role for mTORC1 hyperactivity in mTORopathies, however, whether mTORC2 hyperactivity contributes is not clear. To test this, we inactivated mTORC1 and/or mTORC2 downstream of early Pten deletion in a new mouse model of somatic Pten loss-of-function (LOF) in the cortex and hippocampus. Spontaneous seizures and epileptiform activity persisted despite mTORC1 or mTORC2 inactivation alone, but inactivating both mTORC1 and mTORC2 simultaneously normalized brain activity. These results suggest that hyperactivity of both mTORC1 and mTORC2 can cause epilepsy, and that targeted therapies should aim to reduce activity of both complexes.
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Affiliation(s)
- Erin R Cullen
- Department of Neurological Sciences, Larner College of Medicine, University of VermontBurlingtonUnited States
| | - Mona Safari
- Fralin Biomedical Research Institute at VTC, Center for Neurobiology ResearchRoanokeUnited States
- Translational Biology, Medicine, and Health Graduate ProgramRoanokeUnited States
| | - Isabelle Mittelstadt
- Department of Neurological Sciences, Larner College of Medicine, University of VermontBurlingtonUnited States
| | - Matthew C Weston
- Department of Neurological Sciences, Larner College of Medicine, University of VermontBurlingtonUnited States
- Fralin Biomedical Research Institute at VTC, Center for Neurobiology ResearchRoanokeUnited States
- School of Neuroscience, Virginia Polytechnic and State UniversityBlacksburgUnited States
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5
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Nguyen LH, Xu Y, Nair M, Bordey A. The mTOR pathway genes MTOR, Rheb, Depdc5, Pten, and Tsc1 have convergent and divergent impacts on cortical neuron development and function. eLife 2024; 12:RP91010. [PMID: 38411613 PMCID: PMC10942629 DOI: 10.7554/elife.91010] [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] [Indexed: 02/28/2024] Open
Abstract
Brain somatic mutations in various components of the mTOR complex 1 (mTORC1) pathway have emerged as major causes of focal malformations of cortical development and intractable epilepsy. While these distinct gene mutations converge on excessive mTORC1 signaling and lead to common clinical manifestations, it remains unclear whether they cause similar cellular and synaptic disruptions underlying cortical network hyperexcitability. Here, we show that in utero activation of the mTORC1 activator genes, Rheb or MTOR, or biallelic inactivation of the mTORC1 repressor genes, Depdc5, Tsc1, or Pten in the mouse medial prefrontal cortex leads to shared alterations in pyramidal neuron morphology, positioning, and membrane excitability but different changes in excitatory synaptic transmission. Our findings suggest that, despite converging on mTORC1 signaling, mutations in different mTORC1 pathway genes differentially impact cortical excitatory synaptic activity, which may confer gene-specific mechanisms of hyperexcitability and responses to therapeutic intervention.
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Affiliation(s)
- Lena H Nguyen
- Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at DallasRichardsonUnited States
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Youfen Xu
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Maanasi Nair
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
| | - Angelique Bordey
- Departments of Neurosurgery and Cellular & Molecular Physiology, Wu Tsai Institute, Yale University School of MedicineNew HavenUnited States
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6
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Weiliang W, Yinghao R, Weiliang H, Xiaobin Z, Chenglong Y, Weimiao A, Fei X, Fengpeng W. Identification of hub genes significantly linked to tuberous sclerosis related-epilepsy and lipid metabolism via bioinformatics analysis. Front Neurol 2024; 15:1354062. [PMID: 38419709 PMCID: PMC10899687 DOI: 10.3389/fneur.2024.1354062] [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: 12/11/2023] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
Background Tuberous sclerosis complex (TSC) is one of the most common genetic causes of epilepsy. Identifying differentially expressed lipid metabolism related genes (DELMRGs) is crucial for guiding treatment decisions. Methods We acquired tuberous sclerosis related epilepsy (TSE) datasets, GSE16969 and GSE62019. Differential expression analysis identified 1,421 differentially expressed genes (DEGs). Intersecting these with lipid metabolism related genes (LMRGs) yielded 103 DELMRGs. DELMRGs underwent enrichment analyses, biomarker selection, disease classification modeling, immune infiltration analysis, weighted gene co-expression network analysis (WGCNA) and AUCell analysis. Results In TSE datasets, 103 DELMRGs were identified. Four diagnostic biomarkers (ALOX12B, CBS, CPT1C, and DAGLB) showed high accuracy for epilepsy diagnosis, with an AUC value of 0.9592. Significant differences (p < 0.05) in Plasma cells, T cells regulatory (Tregs), and Macrophages M2 were observed between diagnostic groups. Microglia cells were highly correlated with lipid metabolism functions. Conclusions Our research unveiled potential DELMRGs (ALOX12B, CBS, CPT1C and DAGLB) in TSE, which may provide new ideas for studying the psathogenesis of epilepsy.
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Affiliation(s)
- Wang Weiliang
- Epilepsy Center, Xiamen Humanity Hospital Fujian Medical University, Xiamen, Fujian, China
| | - Ren Yinghao
- Department of Dermatology, Xiamen Humanity Hospital Fujian Medical University, Xiamen, Fujian, China
| | - Hou Weiliang
- Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, State Key Laboratory of Medical Neurobiology, Ministry of Education Frontiers Center for Brain Science and Institutes of Brain Science, Fudan University, Shanghai, China
| | - Zhang Xiaobin
- Epilepsy Center, Xiamen Humanity Hospital Fujian Medical University, Xiamen, Fujian, China
| | - Yang Chenglong
- Department of Neurosurgery, The Cancer Hospital of Harbin Medical University, Harbin, Heilongjiang, China
| | - An Weimiao
- Epilepsy Center, Xiamen Humanity Hospital Fujian Medical University, Xiamen, Fujian, China
| | - Xu Fei
- Department of Pharmacogenomics, College of Bioinformatics Science and Technology, Harbin Medical University, Harbin, China
| | - Wang Fengpeng
- Epilepsy Center, Xiamen Humanity Hospital Fujian Medical University, Xiamen, Fujian, China
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7
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Ragupathi A, Kim C, Jacinto E. The mTORC2 signaling network: targets and cross-talks. Biochem J 2024; 481:45-91. [PMID: 38270460 PMCID: PMC10903481 DOI: 10.1042/bcj20220325] [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: 10/02/2023] [Revised: 11/29/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024]
Abstract
The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.
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Affiliation(s)
- Aparna Ragupathi
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
| | - Christian Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, U.S.A
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8
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Karalis V, Wood D, Teaney NA, Sahin M. The role of TSC1 and TSC2 proteins in neuronal axons. Mol Psychiatry 2024:10.1038/s41380-023-02402-7. [PMID: 38212374 DOI: 10.1038/s41380-023-02402-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/13/2024]
Abstract
Tuberous Sclerosis Complex 1 and 2 proteins, TSC1 and TSC2 respectively, participate in a multiprotein complex with a crucial role for the proper development and function of the nervous system. This complex primarily acts as an inhibitor of the mechanistic target of rapamycin (mTOR) kinase, and mutations in either TSC1 or TSC2 cause a neurodevelopmental disorder called Tuberous Sclerosis Complex (TSC). Neurological manifestations of TSC include brain lesions, epilepsy, autism, and intellectual disability. On the cellular level, the TSC/mTOR signaling axis regulates multiple anabolic and catabolic processes, but it is not clear how these processes contribute to specific neurologic phenotypes. Hence, several studies have aimed to elucidate the role of this signaling pathway in neurons. Of particular interest are axons, as axonal defects are associated with severe neurocognitive impairments. Here, we review findings regarding the role of the TSC1/2 protein complex in axons. Specifically, we will discuss how TSC1/2 canonical and non-canonical functions contribute to the formation and integrity of axonal structure and function.
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Affiliation(s)
- Vasiliki Karalis
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Delaney Wood
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
- Human Neuron Core, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Nicole A Teaney
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Mustafa Sahin
- Rosamund Stone Zander Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
- FM Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA.
- Human Neuron Core, Boston Children's Hospital, Boston, MA, 02115, USA.
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9
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Cullen ER, Safari M, Mittelstadt I, Weston MC. Hyperactivity of mTORC1 and mTORC2-dependent signaling mediate epilepsy downstream of somatic PTEN loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.18.553856. [PMID: 37645923 PMCID: PMC10462128 DOI: 10.1101/2023.08.18.553856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Gene variants that hyperactivate PI3K-mTOR signaling in the brain lead to epilepsy and cortical malformations in humans. Some gene variants associated with these pathologies only hyperactivate mTORC1, but others, such as PTEN, PIK3CA, and AKT, hyperactivate both mTORC1- and mTORC2-dependent signaling. Previous work established a key role for mTORC1 hyperactivity in mTORopathies, however, whether mTORC2 hyperactivity contributes is not clear. To test this, we inactivated mTORC1 and/or mTORC2 downstream of early Pten deletion in a new model of somatic Pten loss-of-function (LOF) in the cortex and hippocampus. Spontaneous seizures and epileptiform activity persisted despite mTORC1 or mTORC2 inactivation alone, but inactivating both mTORC1 and mTORC2 simultaneously normalized brain activity. These results suggest that hyperactivity of both mTORC1 and mTORC2 can cause epilepsy, and that targeted therapies should aim to reduce activity of both complexes.
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Affiliation(s)
- Erin R. Cullen
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Mona Safari
- Fralin Biomedical Research Institute at VTC, Center for Neurobiology Research, Roanoke VA, 24016, USA
| | - Isabelle Mittelstadt
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Matthew C. Weston
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Fralin Biomedical Research Institute at VTC, Center for Neurobiology Research, Roanoke VA, 24016, USA
- School of Neuroscience, Virginia Polytechnic and State University, Blacksburg VA, 24060, USA
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10
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Hu JS, Malik R, Sohal VS, Rubenstein JL, Vogt D. Tsc1 Loss in VIP-Lineage Cortical Interneurons Results in More VIP+ Interneurons and Enhanced Excitability. Cells 2023; 13:52. [PMID: 38201256 PMCID: PMC10777938 DOI: 10.3390/cells13010052] [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: 09/01/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
The mammalian target of rapamycin (mTOR) signaling pathway is a powerful regulator of cell proliferation, growth, synapse maintenance and cell fate. While intensely studied for its role in cancer, the role of mTOR signaling is just beginning to be uncovered in specific cell types that are implicated in neurodevelopmental disorders. Previously, loss of the Tsc1 gene, which results in hyperactive mTOR, was shown to affect the function and molecular properties of GABAergic cortical interneurons (CINs) derived from the medial ganglionic eminence. To assess if other important classes of CINs could be impacted by mTOR dysfunction, we deleted Tsc1 in a caudal ganglionic eminence-derived interneuron group, the vasoactive intestinal peptide (VIP)+ subtype, whose activity disinhibits local circuits. Tsc1 mutant VIP+ CINs reduced their pattern of apoptosis from postnatal days 15-20, resulting in increased VIP+ CINs. The mutant CINs exhibited synaptic and electrophysiological properties that could contribute to the high rate of seizure activity in humans that harbor Tsc1 mutations.
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Affiliation(s)
- Jia Sheng Hu
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Ruchi Malik
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
- Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA 94158, USA
- Center for Integrative Neuroscience, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
| | - Vikaas S. Sohal
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
- Weill Institute for Neurosciences, University of California San Francisco, San Francisco, CA 94158, USA
- Center for Integrative Neuroscience, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
- Sloan-Swartz Center for Theoretical Neurobiology, University of California San Francisco, 1550 4th St., San Francisco, CA 94158, USA
| | - John L. Rubenstein
- Department of Psychiatry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Daniel Vogt
- Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, MI 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA
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11
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Zhang J, Li W, Yue Q, Liu L, Hou ST, Ju J. Rapamycin Exerts an Antidepressant Effect and Enhances Myelination in the Prefrontal Cortex of Chronic Restraint Stress Mice. Neuroscience 2023; 535:99-107. [PMID: 37926147 DOI: 10.1016/j.neuroscience.2023.10.025] [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: 05/18/2023] [Revised: 10/28/2023] [Accepted: 10/31/2023] [Indexed: 11/07/2023]
Abstract
Depressive disorder is a psychiatric condition that is characterized by the core symptoms of anhedonia and learned helplessness. Myelination loss was recently found in the prefrontal cortex (PFC) of patients with depression and animal models, but the mechanism of this loss is unclear. In our previous study, chronic restraint stress (CRS) mice showed depressive-like symptoms. In this study, we found that myelin was reduced in the PFC of CRS mice. We also observed increased mammalian target of rapamycin (mTOR) phosphorylation levels in the PFC. Chronic injections of rapamycin, a mTOR complex inhibitor, prevented depressive behavior as shown by the forced swimming test and sucrose preference test. Rapamycin also increased myelination in the PFC of CRS mice. In summary, we found that CRS enhanced mTOR signaling and reduced myelination in the PFC and that rapamycin could prevent it. Our study provides the etiology of reduced myelin in depressive symptoms and suggests that mTOR signaling could be a target for treating depression or improving myelination deficits in depressive disorders.
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Affiliation(s)
- Jin Zhang
- School of Basic Medical Sciences, Xi'an Medical University, Xi'an, China; State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China
| | - Weifen Li
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China
| | - Qi Yue
- Brain Research Centre and Department of Biology, Southern University of Science and Technology, Shenzhen, China; Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Luping Liu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region
| | - Sheng-Tao Hou
- Brain Research Centre and Department of Biology, Southern University of Science and Technology, Shenzhen, China.
| | - Jun Ju
- Brain Research Centre and Department of Biology, Southern University of Science and Technology, Shenzhen, China.
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12
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Okoh J, Mays J, Bacq A, Oses-Prieto JA, Tyanova S, Chen CJ, Imanbeyev K, Doladilhe M, Zhou H, Jafar-Nejad P, Burlingame A, Noebels J, Baulac S, Costa-Mattioli M. Targeted suppression of mTORC2 reduces seizures across models of epilepsy. Nat Commun 2023; 14:7364. [PMID: 37963879 PMCID: PMC10645975 DOI: 10.1038/s41467-023-42922-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/26/2023] [Indexed: 11/16/2023] Open
Abstract
Epilepsy is a neurological disorder that poses a major threat to public health. Hyperactivation of mTOR complex 1 (mTORC1) is believed to lead to abnormal network rhythmicity associated with epilepsy, and its inhibition is proposed to provide some therapeutic benefit. However, mTOR complex 2 (mTORC2) is also activated in the epileptic brain, and little is known about its role in seizures. Here we discover that genetic deletion of mTORC2 from forebrain neurons is protective against kainic acid-induced behavioral and EEG seizures. Furthermore, inhibition of mTORC2 with a specific antisense oligonucleotide robustly suppresses seizures in several pharmacological and genetic mouse models of epilepsy. Finally, we identify a target of mTORC2, Nav1.2, which has been implicated in epilepsy and neuronal excitability. Our findings, which are generalizable to several models of human seizures, raise the possibility that inhibition of mTORC2 may serve as a broader therapeutic strategy against epilepsy.
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Affiliation(s)
- James Okoh
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Jacqunae Mays
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Alexandre Bacq
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Juan A Oses-Prieto
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Stefka Tyanova
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Chien-Ju Chen
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Novartis Inc, Boston, MA, USA
| | - Khalel Imanbeyev
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Marion Doladilhe
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Hongyi Zhou
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | | | - Alma Burlingame
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Jeffrey Noebels
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Stephanie Baulac
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA.
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA.
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13
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Ramamurthy A, Carvill GL. Raptor Preys on mTOR Imbalance in Tuberous Sclerosis. Epilepsy Curr 2023; 23:193-195. [PMID: 37334409 PMCID: PMC10273816 DOI: 10.1177/15357597231176235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2023] Open
Abstract
Raptor Downregulation Rescues Neuronal Phenotypes in Mouse Models of Tuberous Sclerosis Complex Karalis V, Caval-Holme F, Bateup HS. Nat Commun. 2022;13(1):4665. doi:10.1038/S41467-022-31961-6 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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Affiliation(s)
- Aishwarya Ramamurthy
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine
| | - Gemma Louise Carvill
- Ken and Ruth Davee Department of Neurology, Northwestern University Feinberg School of Medicine
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14
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Tariq K, Cullen E, Getz SA, Conching AK, Goyette AR, Prina ML, Wang W, Li M, Weston MC, Luikart BW. Disruption of mTORC1 rescues neuronal overgrowth and synapse function dysregulated by Pten loss. Cell Rep 2022; 41:111574. [PMID: 36323257 PMCID: PMC9743803 DOI: 10.1016/j.celrep.2022.111574] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/06/2022] [Accepted: 10/06/2022] [Indexed: 11/06/2022] Open
Abstract
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of AKT/mTOR signaling pathway. Mutations in PTEN are found in patients with autism, epilepsy, or macrocephaly. In mouse models, Pten loss results in neuronal hypertrophy, hyperexcitability, seizures, and ASD-like behaviors. The underlying molecular mechanisms of these phenotypes are not well delineated. We determined which of the Pten loss-driven aberrations in neuronal form and function are orchestrated by downstream mTOR complex 1 (mTORC1). Rapamycin-mediated inhibition of mTORC1 prevented increase in soma size, migration, spine density, and dendritic overgrowth in Pten knockout dentate gyrus granule neurons. Genetic knockout of Raptor to disrupt mTORC1 complex formation blocked Pten loss-mediated neuronal hypertrophy. Electrophysiological recordings revealed that genetic disruption of mTORC1 rescued Pten loss-mediated increase in excitatory synaptic transmission. We have identified an essential role for mTORC1 in orchestrating Pten loss-driven neuronal hypertrophy and synapse formation.
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Affiliation(s)
- Kamran Tariq
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Erin Cullen
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Stephanie A. Getz
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Andie K.S. Conching
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Andrew R. Goyette
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Mackenzi L. Prina
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Wei Wang
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Meijie Li
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Matthew C. Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA,These authors contributed equally,Correspondence: (M.C.W.), (B.W.L.)
| | - Bryan W. Luikart
- Department of Molecular and Systems Biology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA,These authors contributed equally,Lead contact,Correspondence: (M.C.W.), (B.W.L.)
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