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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; 29:1165-1178. [PMID: 38212374 DOI: 10.1038/s41380-023-02402-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [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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Garone C, De Giorgio F, Carli S. Mitochondrial metabolism in neural stem cells and implications for neurodevelopmental and neurodegenerative diseases. J Transl Med 2024; 22:238. [PMID: 38438847 PMCID: PMC10910780 DOI: 10.1186/s12967-024-05041-w] [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: 12/29/2023] [Accepted: 02/25/2024] [Indexed: 03/06/2024] Open
Abstract
Mitochondria are cytoplasmic organelles having a fundamental role in the regulation of neural stem cell (NSC) fate during neural development and maintenance.During embryonic and adult neurogenesis, NSCs undergo a metabolic switch from glycolytic to oxidative phosphorylation with a rise in mitochondrial DNA (mtDNA) content, changes in mitochondria shape and size, and a physiological augmentation of mitochondrial reactive oxygen species which together drive NSCs to proliferate and differentiate. Genetic and epigenetic modifications of proteins involved in cellular differentiation (Mechanistic Target of Rapamycin), proliferation (Wingless-type), and hypoxia (Mitogen-activated protein kinase)-and all connected by the common key regulatory factor Hypoxia Inducible Factor-1A-are deemed to be responsible for the metabolic shift and, consequently, NSC fate in physiological and pathological conditions.Both primary mitochondrial dysfunction due to mutations in nuclear DNA or mtDNA or secondary mitochondrial dysfunction in oxidative phosphorylation (OXPHOS) metabolism, mitochondrial dynamics, and organelle interplay pathways can contribute to the development of neurodevelopmental or progressive neurodegenerative disorders.This review analyses the physiology and pathology of neural development starting from the available in vitro and in vivo models and highlights the current knowledge concerning key mitochondrial pathways involved in this process.
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Affiliation(s)
- C Garone
- Department of Medical and Surgical Sciences, Alma Mater Studiorum-University of Bologna, Bologna, Italy.
- IRCCS Istituto Delle Scienze Neurologiche di Bologna, UO Neuropsichiatria Dell'età Pediatrica, Bologna, Italy.
| | - F De Giorgio
- Department of Medical and Surgical Sciences, Alma Mater Studiorum-University of Bologna, Bologna, Italy
| | - S Carli
- Department of Medical and Surgical Sciences, Alma Mater Studiorum-University of Bologna, Bologna, Italy
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Bloom GS, Norambuena A. Dysregulation of mTOR by tau in Alzheimer's disease. Cytoskeleton (Hoboken) 2024; 81:30-34. [PMID: 37638691 PMCID: PMC10919542 DOI: 10.1002/cm.21782] [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: 08/02/2023] [Revised: 08/17/2023] [Accepted: 08/18/2023] [Indexed: 08/29/2023]
Abstract
Tau was discovered in the mid 1970's as a microtubule-associated protein that stimulates tubulin polymerization, and subsequently was shown to be expressed primarily in neurons, where it is most concentrated in axons. Interest in tau rose by the late 1980's, when it was shown to be the principal subunit of the neurofibrillary tangles (NFTs) that accumulate in Alzheimer's disease (AD) brain, and achieved new heights by the late 1990's, when numerous tau mutations were found to be highly penetrant for AD-related disorders that also are associated with NFTs and came to be known as non-Alzheimer's tauopathies. The role of tau in neurodegeneration is far more complex than whatever effects on neurons may be caused by NFTs, however, and here we review our work on dysregulation of mTOR by tau in AD. mTOR is a protein kinase and master regulator of myriad aspects of cellular behavior. We have defined a complex signaling network whereby aberrant tau phosphorylation provoked by amyloid-β oligomers (AβOs), the building blocks of the amyloid plaques that form in AD brain, cause post-mitotic neurons to re-enter the cell cycle, but to die eventually instead of dividing, which may account for most neuron death in AD. Remarkably, we found that this same neuronal signaling network also poisons a fundamental cell biological process that we discovered, nutrient-induced mitochondrial activation, or NiMA. Tau-dependent cell cycle re-entry and NiMA inhibition occur in cultured neurons within a few hours of exposure to AβOs, and thus may represent seminal processes in AD pathogenesis.
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Affiliation(s)
- George S. Bloom
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
- Department of Cell Biology, University of Virginia, Charlottesville, Virginia, USA
- Department of Neuroscience, University of Virginia, Charlottesville, Virginia, USA
| | - Andrés Norambuena
- Department of Biology, University of Virginia, Charlottesville, Virginia, USA
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Ravagnani FG, Valerio HP, Maués JHS, de Oliveira AN, Puga RD, Griesi-Oliveira K, Picosse FR, Ferraz HB, Catharino RR, Ronsein GE, de Carvalho Aguiar P. Omics profile of iPSC-derived astrocytes from Progressive Supranuclear Palsy (PSP) patients. Parkinsonism Relat Disord 2023; 116:105847. [PMID: 37844348 DOI: 10.1016/j.parkreldis.2023.105847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/28/2023] [Accepted: 09/03/2023] [Indexed: 10/18/2023]
Abstract
INTRODUCTION Progressive Supranuclear Palsy (PSP) is a neurodegenerative tauopathy and, to date, the pathophysiological mechanisms in PSP that lead to Tau hyperphosphorylation and neurodegeneration are not clear. In some brain areas, Tau pathology in glial cells appears to precede Tau aggregation in neurons. The development of a model using astrocyte cell lines derived from patients has the potential to identify molecules and pathways that contribute to early events of neurodegeneration. We developed a model of induced pluripotent stem cells (iPSC)-derived astrocytes to investigate the pathophysiology of PSP, particularly early events that might contribute to Tau hyperphosphorylation, applying omics approach to detect differentially expressed genes, metabolites, and proteins, including those from the secretome. METHODS Skin fibroblasts from PSP patients (without MAPT mutations) and controls were reprogrammed to iPSCs, further differentiated into neuroprogenitor cells (NPCs) and astrocytes. In the 5th passage, astrocytes were harvested for total RNA sequencing. Intracellular and secreted proteins were processed for proteomics experiments. Metabolomics profiling was obtained from supernatants only. RESULTS We identified hundreds of differentially expressed genes. The main networks were related to cell cycle re-activation in PSP. Several proteins were found exclusively secreted by the PSP group. The cellular processes related to the cell cycle and mitotic proteins, TriC/CCT pathway, and redox signaling were enriched in the secretome of PSP. Moreover, we found distinct sets of metabolites between PSP and controls. CONCLUSION Our iPSC-derived astrocyte model can provide distinct molecular signatures for PSP patients and it is useful to elucidate the initial stages of PSP pathogenesis.
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Affiliation(s)
| | - Hellen P Valerio
- Institute of Chemistry, Universidade de São Paulo (USP), São Paulo, Brazil
| | - Jersey H S Maués
- Hematology and Hemotherapy Center, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
| | - Arthur N de Oliveira
- Innovare Laboratory, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
| | | | | | - Fabíola R Picosse
- Department of Neurology and Neurosurgery, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Henrique B Ferraz
- Department of Neurology and Neurosurgery, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
| | - Rodrigo R Catharino
- Innovare Laboratory, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
| | | | - Patrícia de Carvalho Aguiar
- Hospital Israelita Albert Einstein, São Paulo, Brazil; Department of Neurology and Neurosurgery, Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil
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Gou Y, Wang L, Zhao J, Xu X, Xu H, Xie F, Wang Y, Feng Y, Zhang J, Zhang Y. PNPLA3-I148M Variant Promotes the Progression of Liver Fibrosis by Inducing Mitochondrial Dysfunction. Int J Mol Sci 2023; 24:ijms24119681. [PMID: 37298640 DOI: 10.3390/ijms24119681] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 05/26/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
Patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 polymorphism (I148M) is strongly associated with non-alcoholic steatohepatitis and advanced fibrosis; however, the underlying mechanisms remain largely unknown. In this study, we investigated the effect of PNPLA3-I148M on the activation of hepatic stellate cell line LX-2 and the progression of liver fibrosis. Immunofluorescence staining and enzyme-linked immunosorbent assay were used to detect lipid accumulation. The expression levels of fibrosis, cholesterol metabolism, and mitochondria-related markers were measured via real-time PCR or western blotting. Electron microscopy was applied to analyze the ultrastructure of the mitochondria. Mitochondrial respiration was measured by a Seahorse XFe96 analyzer. PNPLA3-I148M significantly promoted intracellular free cholesterol aggregation in LX-2 cells by decreasing cholesterol efflux protein (ABCG1) expression; it subsequently induced mitochondrial dysfunction characterized by attenuated ATP production and mitochondrial membrane potential, elevated ROS levels, caused mitochondrial structural damage, altered the oxygen consumption rate, and decreased the expression of mitochondrial-function-related proteins. Our results demonstrated for the first time that PNPLA3-I148M causes mitochondrial dysfunction of LX-2 cells through the accumulation of free cholesterol, thereby promoting the activation of LX-2 cells and the development of liver fibrosis.
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Affiliation(s)
- Yusong Gou
- The Third Unit, The Department of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Lifei Wang
- NHC Key Laboratory of Biotechnology of Antibiotics, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Jinhan Zhao
- The Third Unit, The Department of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Xiaoyi Xu
- The Third Unit, The Department of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Hangfei Xu
- The Third Unit, The Department of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Fang Xie
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Engineering Research Center for Precision Medicine and Transformation of Hepatitis and Liver Cancer, Beijing 100069, China
| | - Yanjun Wang
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Engineering Research Center for Precision Medicine and Transformation of Hepatitis and Liver Cancer, Beijing 100069, China
| | - Yingmei Feng
- Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Jing Zhang
- The Third Unit, The Department of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
| | - Yang Zhang
- Beijing Institute of Hepatology, Beijing Youan Hospital, Capital Medical University, Beijing 100069, China
- Beijing Engineering Research Center for Precision Medicine and Transformation of Hepatitis and Liver Cancer, Beijing 100069, China
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