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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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2
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Praticò AD, Falsaperla R, Comella M, Belfiore G, Polizzi A, Ruggieri M. Case report: A gain-of-function of hamartin may lead to a distinct "inverse TSC1-hamartin" phenotype characterized by reduced cell growth. Front Pediatr 2023; 11:1101026. [PMID: 37063680 PMCID: PMC10098112 DOI: 10.3389/fped.2023.1101026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/28/2023] [Indexed: 04/18/2023] Open
Abstract
Mutations of TSC1 and TSC2 genes cause classical Tuberous Sclerosis Complex (TSC), a neurocutaneous disorder characterized by a tendency to develop hamartias, hamartomas, and other tumors. We herein report on a girl, now aged 5 years, who presented a previously unreported, distinct clinical phenotype consisting of primary microcephaly (head circumference = 40 cm, -5.6 standard deviations), brain anomalies including hypoplasia of the corpus callosum (with a residual draft of the genu), simplified parieto-temporal gyral pattern, colpocephaly with ectasia of the temporal ventricular horns, intellectual disability, and a general pattern of reduced growth (with weight and height < 3rd centiles). No classical features of TSC were recorded; the girl harbored a novel missense variant in TSC1 (c.611G > A). We hypothesize that her clinical phenotype could be related to a "gain-of-function" of the TSC1 protein product hamartin, causing an increase in the effects of the protein on inhibition of its intracellular targets (i.e., mTORC or RAC1 pathways), resulting in a distinct "inverse TSC1-hamartin" phenotype characterized by reduced growth of cells instead of the more classical predisposition to increased cell growth.
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Affiliation(s)
- Andrea D. Praticò
- Unit of Clinical Paediatrics, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
- Correspondence: Andrea D. Praticò Martino Ruggieri
| | - Raffaele Falsaperla
- Units of Neonatology and Neonatal Intensive Care and Paediatrics and Paediatric Emergency, Azienda Ospedaliero Universitaria “Policlinico”, Catania, Italy
| | - Mattia Comella
- Unit of Clinical Paediatrics, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Giuseppe Belfiore
- Unit of Paediatric Radiology, Department of Radiodiagnostics, Azienda Ospedaliero Universitaria “Policlinico”, Catania, Italy
| | - Agata Polizzi
- Chair of Paediatrics, Department of Educational Sciences, University of Catania, Catania, Italy
| | - Martino Ruggieri
- Unit of Clinical Paediatrics, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
- Correspondence: Andrea D. Praticò Martino Ruggieri
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3
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Kohno T, Konno T, Kikuchi S, Kondoh M, Kojima T. Translocation of LSR from tricellular corners causes macropinocytosis at cell-cell interface as a trigger for breaking out of contact inhibition. FASEB J 2021; 35:e21742. [PMID: 34403506 DOI: 10.1096/fj.202100299r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/28/2021] [Accepted: 06/04/2021] [Indexed: 12/29/2022]
Abstract
Withdrawal from contact inhibition is necessary for epithelial cancer precursor cells to initiate cell growth and motility. Nevertheless, little is understood about the mechanism for the sudden initiation of cell growth under static conditions. We focused on cellular junctions as one region where breaking out of contact inhibition occurs. In well-differentiated endometrial cancer cells, Sawano, the ligand administration for tricellular tight junction protein LSR, which transiently decreased the robust junction property, caused an abrupt increase in cell motility and consequent excessive multilayered cell growth despite being under contact inhibition conditions. We observed that macropinocytosis essentially and temporarily occurred as an antecedent event for the above process at intercellular junctions without disruption of the junction apparatus but not at the apical plasma membrane. Collectively, we concluded that the formation of macropinocytosis, which is derived from tight junction-mediated signaling, was triggered for the initiation of cell growth in static precancerous epithelium.
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Affiliation(s)
- Takayuki Kohno
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University, Sapporo, Japan
| | - Takumi Konno
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University, Sapporo, Japan
| | - Shin Kikuchi
- Department of Anatomy, Sapporo Medical University, Sapporo, Japan
| | - Masuo Kondoh
- Drug Innovation Center, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Japan
| | - Takashi Kojima
- Department of Cell Science, Research Institute for Frontier Medicine, Sapporo Medical University, Sapporo, Japan
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4
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Mizuguchi M, Ohsawa M, Kashii H, Sato A. Brain Symptoms of Tuberous Sclerosis Complex: Pathogenesis and Treatment. Int J Mol Sci 2021; 22:ijms22136677. [PMID: 34206526 PMCID: PMC8268912 DOI: 10.3390/ijms22136677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/16/2021] [Accepted: 06/19/2021] [Indexed: 12/12/2022] Open
Abstract
The mammalian target of the rapamycin (mTOR) system plays multiple, important roles in the brain, regulating both morphology, such as cellular size, shape, and position, and function, such as learning, memory, and social interaction. Tuberous sclerosis complex (TSC) is a congenital disorder caused by a defective suppressor of the mTOR system, the TSC1/TSC2 complex. Almost all brain symptoms of TSC are manifestations of an excessive activity of the mTOR system. Many children with TSC are afflicted by intractable epilepsy, intellectual disability, and/or autism. In the brains of infants with TSC, a vicious cycle of epileptic encephalopathy is formed by mTOR hyperactivity, abnormal synaptic structure/function, and excessive epileptic discharges, further worsening epilepsy and intellectual/behavioral disorders. Molecular target therapy with mTOR inhibitors has recently been proved to be efficacious for epilepsy in human TSC patients, and for autism in TSC model mice, indicating the possibility for pharmacological treatment of developmental synaptic disorders.
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Affiliation(s)
- Masashi Mizuguchi
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
- Department of Pediatrics, National Rehabilitation Center for Children with Disabilities, Itabashi-ku, Tokyo 173-0037, Japan
- Correspondence: ; Tel.: +81-3-5841-3515
| | - Maki Ohsawa
- Department of Developmental Medical Sciences, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
- Department of Pediatrics, National Rehabilitation Center for Children with Disabilities, Itabashi-ku, Tokyo 173-0037, Japan
| | - Hirofumi Kashii
- Department of Neuropediatrics, Tokyo Metropolitan Neurological Hospital, Fuchu, Tokyo 183-0042, Japan;
| | - Atsushi Sato
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-8655, Japan;
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Mallela K, Shivananda S, Gopinath KS, Kumar A. Oncogenic role of MiR-130a in oral squamous cell carcinoma. Sci Rep 2021; 11:7787. [PMID: 33833339 PMCID: PMC8032739 DOI: 10.1038/s41598-021-87388-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/26/2021] [Indexed: 02/07/2023] Open
Abstract
Aberrant activation of the PI3K/AKT/mTOR pathway is attributed to the pathogenesis of oral squamous cell carcinoma (OSCC). In recent years, increasing evidence suggests the involvement of microRNAs (miRNAs) in oral carcinogenesis by acting as tumor suppressors or oncogenes. TSC1, as a component of the above pathway, regulates several cellular functions such as cell proliferation, apoptosis, migration and invasion. Downregulation of TSC1 is reported in oral as well as several other cancers and is associated with an unfavourable clinical outcome in patients. Here we show that oncogenic miR-130a binds to the 3′UTR of TSC1 and represses its expression. MiR-130a-mediated repression of TSC1 increases cell proliferation, anchorage independent growth and invasion of OSCC cells, which is dependent on the presence of the 3′UTR in TSC1. We observe an inverse correlation between the expression levels of miR-130a and TSC1 in OSCC samples, suggesting that their interaction is physiologically relevant. Delivery of antagomiR-130a to OSCC cells results in a significant decrease in xenograft size. Taken together, the findings of the study indicate that miR-130a-mediated TSC1 downregulation is not only a novel mechanism in OSCC, but also the restoration of TSC1 levels by antagomiR-130a may be a potential therapeutic strategy for the treatment of OSCC.
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Affiliation(s)
- Karthik Mallela
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India
| | | | | | - Arun Kumar
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India.
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6
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Mallela K, Kumar A. Role of TSC1 in physiology and diseases. Mol Cell Biochem 2021; 476:2269-2282. [PMID: 33575875 DOI: 10.1007/s11010-021-04088-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/27/2021] [Indexed: 12/15/2022]
Abstract
Since its initial discovery as the gene altered in Tuberous Sclerosis Complex (TSC), an autosomal dominant disorder, the interest in TSC1 (Tuberous Sclerosis Complex 1) has steadily risen. TSC1, an essential component of the pro-survival PI3K/AKT/MTOR signaling pathway, plays an important role in processes like development, cell growth and proliferation, survival, autophagy and cilia development by co-operating with a variety of regulatory molecules. Recent studies have emphasized the tumor suppressive role of TSC1 in several human cancers including liver, lung, bladder, breast, ovarian, and pancreatic cancers. TSC1 perceives inputs from various signaling pathways, including TNF-α/IKK-β, TGF-β-Smad2/3, AKT/Foxo/Bim, Wnt/β-catenin/Notch, and MTOR/Mdm2/p53 axis, thereby regulating cancer cell proliferation, metabolism, migration, invasion, and immune regulation. This review provides a first comprehensive evaluation of TSC1 and illuminates its diverse functions apart from its involvement in TSC genetic disorder. Further, we have summarized the physiological functions of TSC1 in various cellular events and conditions whose dysregulation may lead to several pathological manifestations including cancer.
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Affiliation(s)
- Karthik Mallela
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India
| | - Arun Kumar
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, 560012, India.
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7
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Wang J, Li X, Zhong M, Wang Y, Zou L, Wang M, Gong X, Wang X, Zhou C, Ma X, Liu M. miR-301a Suppression within Fibroblasts Limits the Progression of Fibrosis through the TSC1/mTOR Pathway. MOLECULAR THERAPY. NUCLEIC ACIDS 2020; 21:217-228. [PMID: 32585629 PMCID: PMC7321782 DOI: 10.1016/j.omtn.2020.05.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/18/2020] [Accepted: 05/22/2020] [Indexed: 01/06/2023]
Abstract
Pulmonary fibrosis has been characterized by abnormal proliferation of fibroblasts and massive deposition of the extracellular matrix, which results from a complex interplay of chronic injury and inflammatory responses. MicroRNA-301a (miR-301a) is activated by multiple inflammatory stimulators, contributing to multiple tumorigenesis and autoimmune diseases. This study showed that miR-301a was overexpressed in a bleomycin-induced murine model of pulmonary fibrosis and patients with idiopathic pulmonary fibrosis (IPF). In addition, miR-301a was activated by transforming growth factor β (TGF-β) and interleukin 6 (IL-6) in normal and IPF fibroblasts, which was markedly reversed by the signal transducer and activator of transcription 3 (STAT3) inhibitor. The genetic ablation of miR-301a in mice reduced bleomycin-induced lung fibrosis, and the downregulation of miR-301a restrained proliferation and activation of fibroblasts. Furthermore, this study demonstrated that TSC1 was a functional target of miR-301a in fibroblasts, and the negative regulation of TSC1 by miR-301a promoted the severity of pulmonary fibrosis through the mammalian target of rapamycin (mTOR) signaling pathway. The blocking of miR-301a by the intravenous injection of antagomiR-301a inhibited the proliferation of fibroblasts and the structural destruction of lung tissues in the bleomycin-induced lung fibrosis mouse model. The findings revealed the crucial role of the miR-301a/TSC1/mTOR axis in the pathogenesis of pulmonary fibrosis, suggesting that miR-301a might serve as a potential therapeutic target.
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Affiliation(s)
- Jiexuan Wang
- National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Xun Li
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China
| | - Mingtian Zhong
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China
| | - Yansheng Wang
- National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China
| | - Liming Zou
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China
| | - Miaomiao Wang
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China
| | - Xiaoli Gong
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China
| | - Xinjie Wang
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China
| | - Chengzhi Zhou
- National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China.
| | - Xiaodong Ma
- Institute for Brain Research and Rehabilitation, Guangdong Key Laboratory of Mental Health and Cognitive Science, Center for Studies of Psychological Application, South China Normal University, Guangzhou 510631, China.
| | - Ming Liu
- National Clinical Research Center for Respiratory Disease, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, China.
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8
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Xu S, Zhang Y, Wang J, Li K, Tan K, Liang K, Shen J, Cai D, Jin D, Li M, Xiao G, Xu J, Jiang Y, Bai X. TSC1 regulates osteoclast podosome organization and bone resorption through mTORC1 and Rac1/Cdc42. Cell Death Differ 2018; 25:1549-1566. [PMID: 29358671 DOI: 10.1038/s41418-017-0049-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 11/13/2017] [Accepted: 11/27/2017] [Indexed: 01/08/2023] Open
Abstract
Reorganization of the podosome into the sealing zone is crucial for osteoclasts (OCLs) to resorb bone, but the underlying mechanisms are unclear. Here, we show that tuberous sclerosis complex 1 (TSC1) functions centrally in OCLs to promote podosome organization and bone resorption through mechanistic target of rapamycin complex 1 (mTORC1) and the small GTPases Rac1/Cdc42. During osteoclastogenesis, enhanced expression of TSC1 downregulates mTORC1 activity. TSC1 deletion in OCLs reduced podosome belt formation in vitro and sealing zone formation in vivo, leading to bone resorption deficiency and osteopetrosis. Mechanistically, TSC1 promoted podosome superstructure assembly by releasing mTORC1-dependent negative feedback inhibition of Rac1/Cdc42. Rapamycin and active Rac1/Cdc42 restore podosome organization and bone resorption and alleviate osteopetrotic phenotypes in mutant mice. Our findings reveal an essential role of TSC1 signaling in the regulation of bone resorption. Targeting TSC1 represents a novel strategy to inhibit bone resorption and prevent bone loss-related diseases.
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Affiliation(s)
- Song Xu
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Department of Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Yue Zhang
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Jian Wang
- Department of Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China
| | - Kai Li
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Kang Tan
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Kangyan Liang
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Junhui Shen
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Daozhang Cai
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Dadi Jin
- Academy of Orthopedics, Guangdong Province, The Third Affiliated Hospital of Southern Medical University, Guangzhou, 510630, China
| | - Mangmang Li
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Guozhi Xiao
- Department of Biochemistry and Department of Biology and Shenzhen Key Laboratory of Cell Microenvironment, South University of Science and Technology of China, Shenzhen, 518055, China
| | - Jiake Xu
- Molecular Laboratory, School of Pathology and Laboratory Medicine, The University of Western Australia, M504, Perth, 6009, Australia
| | - Yu Jiang
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, 15260, USA
| | - Xiaochun Bai
- Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China. .,Department of Arthroplasty, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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The Andes Virus Nucleocapsid Protein Directs Basal Endothelial Cell Permeability by Activating RhoA. mBio 2016; 7:mBio.01747-16. [PMID: 27795403 PMCID: PMC5080385 DOI: 10.1128/mbio.01747-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Andes virus (ANDV) predominantly infects microvascular endothelial cells (MECs) and nonlytically causes an acute pulmonary edema termed hantavirus pulmonary syndrome (HPS). In HPS patients, virtually every pulmonary MEC is infected, MECs are enlarged, and infection results in vascular leakage and highly lethal pulmonary edema. We observed that MECs infected with the ANDV hantavirus or expressing the ANDV nucleocapsid (N) protein showed increased size and permeability by activating the Rheb and RhoA GTPases. Expression of ANDV N in MECs increased cell size by preventing tuberous sclerosis complex (TSC) repression of Rheb-mTOR-pS6K. N selectively bound the TSC2 N terminus (1 to 1403) within a complex containing TSC2/TSC1/TBC1D7, and endogenous TSC2 reciprocally coprecipitated N protein from ANDV-infected MECs. TSCs normally restrict RhoA-induced MEC permeability, and we found that ANDV infection or N protein expression constitutively activated RhoA. This suggests that the ANDV N protein alone is sufficient to activate signaling pathways that control MEC size and permeability. Further, RhoA small interfering RNA, dominant-negative RhoA(N19), and the RhoA/Rho kinase inhibitors fasudil and Y27632 dramatically reduced the permeability of ANDV-infected MECs by 80 to 90%. Fasudil also reduced the bradykinin-directed permeability of ANDV and Hantaan virus-infected MECs to control levels. These findings demonstrate that ANDV activation of RhoA causes MEC permeability and reveal a potential edemagenic mechanism for ANDV to constitutively inhibit the basal barrier integrity of infected MECs. The central importance of RhoA activation in MEC permeability further suggests therapeutically targeting RhoA, TSCs, and Rac1 as potential means of resolving capillary leakage during hantavirus infections. HPS is hallmarked by acute pulmonary edema, hypoxia, respiratory distress, and the ubiquitous infection of pulmonary MECs that occurs without disrupting the endothelium. Mechanisms of MEC permeability and targets for resolving lethal pulmonary edema during HPS remain enigmatic. Our findings suggest a novel underlying mechanism of MEC dysfunction resulting from ANDV activation of the Rheb and RhoA GTPases that, respectively, control MEC size and permeability. Our studies show that inhibition of RhoA blocks ANDV-directed permeability and implicate RhoA as a potential therapeutic target for restoring capillary barrier function to the ANDV-infected endothelium. Since RhoA activation forms a downstream nexus for factors that cause capillary leakage, blocking RhoA activation is liable to restore basal capillary integrity and prevent edema amplified by tissue hypoxia and respiratory distress. Targeting the endothelium has the potential to resolve disease during symptomatic stages, when replication inhibitors lack efficacy, and to be broadly applicable to other hemorrhagic and edematous viral diseases.
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Roohi A, Hojjat-Farsangi M. Recent advances in targeting mTOR signaling pathway using small molecule inhibitors. J Drug Target 2016; 25:189-201. [PMID: 27632356 DOI: 10.1080/1061186x.2016.1236112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Targeted-based cancer therapy (TBCT) or personalized medicine is one of the main treatment modalities for cancer that has been developed to decrease the undesirable effects of chemotherapy. Targeted therapy inhibits the growth of tumor cells by interrupting with particular molecules required for tumorigenesis and proliferation of tumor cells rather than interfering with dividing normal cells. Therefore, targeted therapies are anticipated to be more efficient than former tumor treatment agents with minimal side effects on non-tumor cells. Small molecule inhibitors (SMIs) are currently one of the most investigated anti-tumor agents of TBCT. These small organic agents target several vital molecules involved in cell biological processes and induce target cells apoptosis and necrosis. Mechanistic (mammalian) target of rapamycin (mTOR) complexes (mTORC1/2) control different intracellular processes, including growth, proliferation, angiogenesis and metabolism. Signaling pathways, in which mTOR complexes are involved in are usually dysregulated in various tumors and have been shown to be ideal targets for SMIs. Currently, different mTOR-SMIs are in the clinic for the treatment of cancer patients, and several others are in preclinical or clinical settings. In this review, we summarize recent advances in developing different mTOR inhibitors, which are currently in preclinical and clinical investigations or have been approved for cancer treatment.
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Affiliation(s)
- Azam Roohi
- a Department of Immunology, School of Public Health , Tehran University of Medical Sciences , Tehran , Iran
| | - Mohammad Hojjat-Farsangi
- b Department of Oncology-Pathology, Immune and Gene therapy Lab , Cancer Center Karolinska (CCK), Karolinska University Hospital Solna and Karolinska Institute , Stockholm , Sweden.,c Department of Immunology, School of Medicine , Bushehr University of Medical Sciences , Bushehr , Iran
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11
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Inability to activate Rac1-dependent forgetting contributes to behavioral inflexibility in mutants of multiple autism-risk genes. Proc Natl Acad Sci U S A 2016; 113:7644-9. [PMID: 27335463 DOI: 10.1073/pnas.1602152113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The etiology of autism is so complicated because it involves the effects of variants of several hundred risk genes along with the contribution of environmental factors. Therefore, it has been challenging to identify the causal paths that lead to the core autistic symptoms such as social deficit, repetitive behaviors, and behavioral inflexibility. As an alternative approach, extensive efforts have been devoted to identifying the convergence of the targets and functions of the autism-risk genes to facilitate mapping out causal paths. In this study, we used a reversal-learning task to measure behavioral flexibility in Drosophila and determined the effects of loss-of-function mutations in multiple autism-risk gene homologs in flies. Mutations of five autism-risk genes with diversified molecular functions all led to a similar phenotype of behavioral inflexibility indicated by impaired reversal-learning. These reversal-learning defects resulted from the inability to forget or rather, specifically, to activate Rac1 (Ras-related C3 botulinum toxin substrate 1)-dependent forgetting. Thus, behavior-evoked activation of Rac1-dependent forgetting has a converging function for autism-risk genes.
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12
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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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Usatyuk PV, Fu P, Mohan V, Epshtein Y, Jacobson JR, Gomez-Cambronero J, Wary KK, Bindokas V, Dudek SM, Salgia R, Garcia JGN, Natarajan V. Role of c-Met/phosphatidylinositol 3-kinase (PI3k)/Akt signaling in hepatocyte growth factor (HGF)-mediated lamellipodia formation, reactive oxygen species (ROS) generation, and motility of lung endothelial cells. J Biol Chem 2014; 289:13476-91. [PMID: 24634221 DOI: 10.1074/jbc.m113.527556] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hepatocyte growth factor (HGF) mediated signaling promotes cell proliferation and migration in a variety of cell types and plays a key role in tumorigenesis. As cell migration is important to angiogenesis, we characterized HGF-mediated effects on the formation of lamellipodia, a pre-requisite for migration using human lung microvascular endothelial cells (HLMVECs). HGF, in a dose-dependent manner, induced c-Met phosphorylation (Tyr-1234/1235, Tyr-1349, Ser-985, Tyr-1003, and Tyr-1313), activation of PI3k (phospho-Yp85) and Akt (phospho-Thr-308 and phospho-Ser-473) and potentiated lamellipodia formation and HLMVEC migration. Inhibition of c-Met kinase by SU11274 significantly attenuated c-Met, PI3k, and Akt phosphorylation, suppressed lamellipodia formation and endothelial cell migration. LY294002, an inhibitor of PI3k, abolished HGF-induced PI3k (Tyr-458), and Akt (Thr-308 and Ser-473) phosphorylation and suppressed lamellipodia formation. Furthermore, HGF stimulated p47(phox)/Cortactin/Rac1 translocation to lamellipodia and ROS generation. Moreover, inhibition of c-Met/PI3k/Akt signaling axis and NADPH oxidase attenuated HGF- induced lamellipodia formation, ROS generation and cell migration. Ex vivo experiments with mouse aortic rings revealed a role for c-Met signaling in HGF-induced sprouting and lamellipodia formation. Taken together, these data provide evidence in support of a significant role for HGF-induced c-Met/PI3k/Akt signaling and NADPH oxidase activation in lamellipodia formation and motility of lung endothelial cells.
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