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Huang HZ, Ai WQ, Wei N, Zhu LS, Liu ZQ, Zhou CW, Deng MF, Zhang WT, Zhang JC, Yang CQ, Hu YZ, Han ZT, Zhang HH, Jia JJ, Wang J, Liu FF, Li K, Xu Q, Yuan M, Man H, Guo Z, Lu Y, Shu K, Zhu LQ, Liu D. Senktide blocks aberrant RTN3 interactome to retard memory decline and tau pathology in social isolated Alzheimer's disease mice. Protein Cell 2024; 15:261-284. [PMID: 38011644 PMCID: PMC10984625 DOI: 10.1093/procel/pwad056] [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: 10/19/2023] [Accepted: 11/06/2023] [Indexed: 11/29/2023] Open
Abstract
Sporadic or late-onset Alzheimer's disease (LOAD) accounts for more than 95% of Alzheimer's disease (AD) cases without any family history. Although genome-wide association studies have identified associated risk genes and loci for LOAD, numerous studies suggest that many adverse environmental factors, such as social isolation, are associated with an increased risk of dementia. However, the underlying mechanisms of social isolation in AD progression remain elusive. In the current study, we found that 7 days of social isolation could trigger pattern separation impairments and presynaptic abnormalities of the mossy fibre-CA3 circuit in AD mice. We also revealed that social isolation disrupted histone acetylation and resulted in the downregulation of 2 dentate gyrus (DG)-enriched miRNAs, which simultaneously target reticulon 3 (RTN3), an endoplasmic reticulum protein that aggregates in presynaptic regions to disturb the formation of functional mossy fibre boutons (MFBs) by recruiting multiple mitochondrial and vesicle-related proteins. Interestingly, the aggregation of RTN3 also recruits the PP2A B subunits to suppress PP2A activity and induce tau hyperphosphorylation, which, in turn, further elevates RTN3 and forms a vicious cycle. Finally, using an artificial intelligence-assisted molecular docking approach, we determined that senktide, a selective agonist of neurokinin3 receptors (NK3R), could reduce the binding of RTN3 with its partners. Moreover, application of senktide in vivo effectively restored DG circuit disorders in socially isolated AD mice. Taken together, our findings not only demonstrate the epigenetic regulatory mechanism underlying mossy fibre synaptic disorders orchestrated by social isolation and tau pathology but also reveal a novel potential therapeutic strategy for AD.
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Affiliation(s)
- He-Zhou Huang
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Wen-Qing Ai
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Na Wei
- Department of Pathology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450002, China
- Department of Pathology, School of Basic Medicine, Zhengzhou University, Zhengzhou 450002, China
| | - Ling-Shuang Zhu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhi-Qiang Liu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chao-Wen Zhou
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Man-Fei Deng
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Wen-Tao Zhang
- The Second Affiliated Hospital, Department of Neurology, Hengyang Medical School, University of South China, Hengyang 421001, China
| | - Jia-Chen Zhang
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chun-Qing Yang
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Ya-Zhuo Hu
- Beijing Key Laboratory of Aging and Geriatrics, National Clinical Research Center for Geriatric Disease, Institute of Geriatrics, Chinese PLA General Hospital and Chinese PLA Medical Academy, Beijing 100853, China
| | - Zhi-Tao Han
- Beijing Key Laboratory of Aging and Geriatrics, National Clinical Research Center for Geriatric Disease, Institute of Geriatrics, Chinese PLA General Hospital and Chinese PLA Medical Academy, Beijing 100853, China
| | - Hong-Hong Zhang
- Beijing Key Laboratory of Aging and Geriatrics, National Clinical Research Center for Geriatric Disease, Institute of Geriatrics, Chinese PLA General Hospital and Chinese PLA Medical Academy, Beijing 100853, China
| | - Jian-Jun Jia
- Beijing Key Laboratory of Aging and Geriatrics, National Clinical Research Center for Geriatric Disease, Institute of Geriatrics, Chinese PLA General Hospital and Chinese PLA Medical Academy, Beijing 100853, China
| | - Jing Wang
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Fang-Fang Liu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Ke Li
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qi Xu
- Department of Neurology, Union Hospital, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Mei Yuan
- The Second Affiliated Hospital, Department of Neurology, Hengyang Medical School, University of South China, Hengyang 421001, China
| | - Hengye Man
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Ziyuan Guo
- Center for Stem Cell and Organoid Medicine (CuSTOM), Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Youming Lu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Kai Shu
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Ling-Qiang Zhu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Dan Liu
- Department of Medical Genetics, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Koutarapu S, Ge J, Jha D, Blennow K, Zetterberg H, Lashley T, Michno W, Hanrieder J. Correlative Chemical Imaging Identifies Amyloid Peptide Signatures of Neuritic Plaques and Dystrophy in Human Sporadic Alzheimer's Disease. Brain Connect 2023; 13:297-306. [PMID: 36074939 PMCID: PMC10398722 DOI: 10.1089/brain.2022.0047] [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: 11/12/2022] Open
Abstract
Objective: Alzheimer's disease (AD) is the most common neurodegenerative disease. The predominantly sporadic form of AD is age-related, but the underlying pathogenic mechanisms remain not fully understood. Current efforts to combat the disease focus on the main pathological hallmarks, in particular beta-amyloid (Aβ) plaque pathology. According to the amyloid cascade hypothesis, Aβ is the critical early initiator of AD pathogenesis. Plaque pathology is very heterogeneous, where a subset of plaques, neuritic plaques (NPs), are considered most neurotoxic rendering their in-depth characterization essential to understand Aβ pathogenicity. Methods: To delineate the chemical traits specific to NP types, we investigated senile Aβ pathology in the postmortem, human sporadic AD brain using advanced correlative biochemical imaging based on immunofluorescence (IF) microscopy and mass spectrometry imaging (MSI). Results: Immunostaining-guided MSI identified distinct Aβ signatures of NPs characterized by increased Aβ1-42(ox) and Aβ2-42. Moreover, correlation with a marker of dystrophy (reticulon 3 [RTN3]) identified key Aβ species that both delineate NPs and display association with neuritic dystrophy. Conclusion: Together, these correlative imaging data shed light on the complex biochemical architecture of NPs and associated dystrophic neurites. These in turn are obvious targets for disease-modifying treatment strategies, as well as novel biomarkers of Aβ pathogenicity.
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Affiliation(s)
- Srinivas Koutarapu
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
| | - Junyue Ge
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
| | - Durga Jha
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
- RECETOX, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Kaj Blennow
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, London, United Kingdom
- UK Dementia Research Institute, University College London, London, United Kingdom
- Hong Kong Center for Neurodegenerative Diseases, Hong Kong, China
| | - Tammaryn Lashley
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, London, United Kingdom
- Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Neurosciences, Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Wojciech Michno
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
- Department of Pediatrics, Stanford University School of Medicine, Stanford University, Palo Alto, California, USA
| | - Jörg Hanrieder
- Department of Psychiatry and Neurochemistry, Sahlgrenska Academy, University of Gothenburg, Mölndal, Sweden
- Department of Neurodegenerative Disease, Institute of Neurology, University College London, London, United Kingdom
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Song S, Liu B, Zeng X, Wu Y, Chen H, Wu H, Gu J, Gao X, Ruan Y, Wang H. Reticulon 2 promotes gastric cancer metastasis via activating endoplasmic reticulum Ca2+ efflux-mediated ERK signalling. Cell Death Dis 2022; 13:349. [PMID: 35428758 PMCID: PMC9012842 DOI: 10.1038/s41419-022-04757-1] [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] [Received: 04/21/2021] [Revised: 03/01/2022] [Accepted: 03/17/2022] [Indexed: 11/16/2022]
Abstract
Gastric cancer ranks fourth for mortality globally among various malignant tumours, and invasion and metastasis are the major reason leading to its poor prognosis. Recently, accumulating studies revealed the role of reticulon proteins in cell growth and transmigration. However, the expression and biological function of reticulon proteins in human gastric cancer remain largely unclear. Herein, we explored the potential role of reticulon 2 (RTN2) in the progression of gastric cancer. Tissue microarray was used to determine the expression levels of RTN2 in 267 gastric cancer patients by immunohistochemistry. Gastric cancer cell lines were utilised to examine the influences of RTN2 on cellular migration and invasion abilities, epithelial-to-mesenchymal transition (EMT) and signalling pathway. In vivo studies were also performed to detect the effect of RTN2 on tumour metastasis. We found that RTN2 expression was notably upregulated in tumour tissues compared to pericarcinomatous tissues. High RTN2 expression was positively correlated with patients’ age, vessel invasion, tumour invasion depth, lymph node metastasis and TNM stage. Besides, high RTN2 staining intensity was associated with adverse survival which was further identified as an independent prognostic factor for gastric cancer patients by multivariate analysis. And the predictive accuracy was also improved when incorporated RTN2 into the TNM-staging system. RTN2 could promote the proliferation, migration and invasion of gastric cancer cells in vitro and lung metastasis in vivo. Mechanistically, RTN2 interacted with IP3R, and activated ERK signalling pathway via facilitating Ca2+ release from the endoplasmic reticulum, and subsequently drove EMT in gastric cancer cells. These results proposed RTN2 as a novel promotor and potential molecular target for gastric cancer therapies.
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Microglial VPS35 deficiency impairs Aβ phagocytosis and Aβ-induced disease-associated microglia, and enhances Aβ associated pathology. J Neuroinflammation 2022; 19:61. [PMID: 35236374 PMCID: PMC8892702 DOI: 10.1186/s12974-022-02422-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/18/2022] [Indexed: 12/14/2022] Open
Abstract
Background Vacuolar sorting protein 35 (VPS35), a key component of the retromer, plays an essential role in selectively retrieval of transmembrane proteins from endosomes to trans-Golgi networks. Dysfunctional retromer is a risk factor for neurodegenerative disorders, including Alzheimer’s disease (AD). Microglial VPS35 deficiency is found in AD patients’ brain; however, it remains unclear if and how microglial VPS35-loss contributes to AD development. Methods We used mice with VPS35 cKO (conditional knockout) in microglial cells in 5XFAD, an AD mouse model. The AD related brain pathology (Aβ and glial activation), behavior, and phagocytosis of Aβ were accessed by a combination of immunofluorescence staining analyses and neurological behavior tests. Results A decrease in learning and memory function, but increases in insoluble, fibrillar, and plaques of β-amyloids (Aβ), dystrophic neurites, and reactive astrocytes are observed in microglial VPS35 deficient 5XFAD mice. Further examining microglial phenotype demonstrates necessity of microglial VPS35 in disease-associated microglia (DAM) development and microglial uptake of Aβ, revealing a tight association of microglial Aβ uptake with DAM development. Conclusions Together, these results uncovered a mechanism by which microglial VPS35-deficiency precipitates AD pathology in 5XFAD mice likely by impairing DAM development and DAM mediated Aβ uptake and clearance, and thus accelerating the cognition decline. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-022-02422-0.
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Jackson TC, Herrmann JR, Garman RH, Kang RD, Vagni VA, Gorse K, Janesko-Feldman K, Stezoski J, Kochanek PM. Hypoxia-ischemia-mediated effects on neurodevelopmentally regulated cold-shock proteins in neonatal mice under strict temperature control. Pediatr Res 2022:10.1038/s41390-022-01990-4. [PMID: 35184138 PMCID: PMC9388702 DOI: 10.1038/s41390-022-01990-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/18/2021] [Accepted: 01/17/2022] [Indexed: 11/08/2022]
Abstract
BACKGROUND Neonates have high levels of cold-shock proteins (CSPs) in the normothermic brain for a limited period following birth. Hypoxic-ischemic (HI) insults in term infants produce neonatal encephalopathy (NE), and it remains unclear whether HI-induced pathology alters baseline CSP expression in the normothermic brain. METHODS Here we established a version of the Rice-Vannucci model in PND 10 mice that incorporates rigorous temperature control. RESULTS Common carotid artery (CCA)-ligation plus 25 min hypoxia (8% O2) in pups with targeted normothermia resulted in classic histopathological changes including increased hippocampal degeneration, astrogliosis, microgliosis, white matter changes, and cell signaling perturbations. Serial assessment of cortical, thalamic, and hippocampal RNA-binding motif 3 (RBM3), cold-inducible RNA binding protein (CIRBP), and reticulon-3 (RTN3) revealed a rapid age-dependent decrease in levels in sham and injured pups. CSPs were minimally affected by HI and the age point of lowest expression (PND 18) coincided with the timing at which heat-generating mechanisms mature in mice. CONCLUSIONS The findings suggest the need to determine whether optimized therapeutic hypothermia (depth and duration) can prevent the age-related decline in neuroprotective CSPs like RBM3 in the brain, and improve outcomes during critical phases of secondary injury and recovery after NE. IMPACT The rapid decrease in endogenous neuroprotective cold-shock proteins (CSPs) in the normothermic cortex, thalamus, and hippocampus from postnatal day (PND) 11-18, coincides with the timing of thermogenesis maturation in neonatal mice. Hypoxia-ischemia (HI) has a minor impact on the normal age-dependent decline in brain CSP levels in neonates maintained normothermic post-injury. HI robustly disrupts the expected correlation in RNA-binding motif 3 (RBM3) and reticulon-3 (RTN3). The potent neuroprotectant RBM3 is not increased 1-4 days after HI in a mouse model of neonatal encephalopathy (NE) in the term newborn and in which rigorous temperature control prevents the manifestation of endogenous post-insult hypothermia.
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Affiliation(s)
- Travis C Jackson
- University of South Florida Morsani College of Medicine, USF Health Heart Institute, MDD 0630, 560 Channelside Drive, Tampa, FL, 33602, USA.
- Department of Molecular Pharmacology & Physiology, University of South Florida Morsani College of Medicine, 12901 Bruce B Downs Boulevard, Tampa, FL, 33612-4799, USA.
| | - Jeremy R Herrmann
- Safar Center for Resuscitation Research, UPMC Children's Hospital of Pittsburgh, Rangos Research Center-6th floor, Pittsburgh, PA, 15224, USA
| | - Robert H Garman
- Division of Neuropathology, University of Pittsburgh, 3550 Terrrace Street, Pittsburgh, PA, 15261, USA
| | - Richard D Kang
- University of South Florida Morsani College of Medicine, USF Health Heart Institute, MDD 0630, 560 Channelside Drive, Tampa, FL, 33602, USA
- Department of Molecular Pharmacology & Physiology, University of South Florida Morsani College of Medicine, 12901 Bruce B Downs Boulevard, Tampa, FL, 33612-4799, USA
| | - Vincent A Vagni
- Safar Center for Resuscitation Research, UPMC Children's Hospital of Pittsburgh, Rangos Research Center-6th floor, Pittsburgh, PA, 15224, USA
| | - Kiersten Gorse
- University of South Florida Morsani College of Medicine, USF Health Heart Institute, MDD 0630, 560 Channelside Drive, Tampa, FL, 33602, USA
- Department of Molecular Pharmacology & Physiology, University of South Florida Morsani College of Medicine, 12901 Bruce B Downs Boulevard, Tampa, FL, 33612-4799, USA
| | - Keri Janesko-Feldman
- Safar Center for Resuscitation Research, UPMC Children's Hospital of Pittsburgh, Rangos Research Center-6th floor, Pittsburgh, PA, 15224, USA
| | - Jason Stezoski
- Safar Center for Resuscitation Research, UPMC Children's Hospital of Pittsburgh, Rangos Research Center-6th floor, Pittsburgh, PA, 15224, USA
| | - Patrick M Kochanek
- Safar Center for Resuscitation Research, UPMC Children's Hospital of Pittsburgh, Rangos Research Center-6th floor, Pittsburgh, PA, 15224, USA
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Sharoar MG, Zhou J, Benoit M, He W, Yan R. Dynactin 6 deficiency enhances aging-associated dystrophic neurite formation in mouse brains. Neurobiol Aging 2021; 107:21-29. [PMID: 34371284 DOI: 10.1016/j.neurobiolaging.2021.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/17/2021] [Accepted: 07/07/2021] [Indexed: 11/25/2022]
Abstract
Formation of Reticulon 3 (RTN3)-immunoreactive dystrophic neurites (RIDNs) occurs early during the growth of amyloid plaques in Alzheimer's disease (AD) brains. We have shown that RIDNs in AD and aging mouse brains are composed of abnormally clustered tubular endoplasmic reticulum (ER) and degenerating mitochondria. To understand RTN3-mediated abnormal tubular ER clustering, we aimed to identify proteins that interact with RTN3 and impact accumulation of tubular ER in RIDNs. We found that the N-terminal domain of RTN3, which is unique among RTN family members, specifically interacted with dynactin 6 (DCTN6), a protein involved in dynein-mediated retrograde transport of cargo vesicles. DCTN6 protein levels decrease with aging in the hippocampal regions of WT mice. We found that DCTN6 deficiency enhanced RTN3 protein levels, high molecular weight RTN3 levels, and hippocampus-specific RIDN formation in aging brains of transgenic mice overexpressing RTN3. Our results suggest that the DCTN6-RTN3 interaction mediates tubular ER trafficking in axons, and a DCTN6 deficiency in the hippocampus impairs axonal ER trafficking, leading to abnormal ER accumulation and RIDN formation in brains of aging mice.
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Affiliation(s)
- Md Golam Sharoar
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA.
| | - John Zhou
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA; Molecular Medicine Graduate Program, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH., USA
| | - Marc Benoit
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA
| | - Wanxia He
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA; Molecular Medicine Graduate Program, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH., USA
| | - Riqiang Yan
- Department of Neuroscience, University of Connecticut Health, Farmington, CT., USA
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Yi C, Goh KY, Wong L, Ramanujan A, Tanaka K, Sajikumar S, Ibáñez CF. Inactive variants of death receptor p75 NTR reduce Alzheimer's neuropathology by interfering with APP internalization. EMBO J 2021; 40:e104450. [PMID: 33258176 PMCID: PMC7809794 DOI: 10.15252/embj.2020104450] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 10/14/2020] [Accepted: 10/19/2020] [Indexed: 01/04/2023] Open
Abstract
A prevalent model of Alzheimer's disease (AD) pathogenesis postulates the generation of neurotoxic fragments derived from the amyloid precursor protein (APP) after its internalization to endocytic compartments. The molecular pathways that regulate APP internalization and intracellular trafficking in neurons are incompletely understood. Here, we report that 5xFAD mice, an animal model of AD, expressing signaling-deficient variants of the p75 neurotrophin receptor (p75NTR ) show greater neuroprotection from AD neuropathology than animals lacking this receptor. p75NTR knock-in mice lacking the death domain or transmembrane Cys259 showed lower levels of Aβ species, amyloid plaque burden, gliosis, mitochondrial stress, and neurite dystrophy than global knock-outs. Strikingly, long-term synaptic plasticity and memory, which are completely disrupted in 5xFAD mice, were fully recovered in the knock-in mice. Mechanistically, we found that p75NTR interacts with APP at the plasma membrane and regulates its internalization and intracellular trafficking in hippocampal neurons. Inactive p75NTR variants internalized considerably slower than wild-type p75NTR and showed increased association with the recycling pathway, thereby reducing APP internalization and co-localization with BACE1, the critical protease for generation of neurotoxic APP fragments, favoring non-amyloidogenic APP cleavage. These results reveal a novel pathway that directly and specifically regulates APP internalization, amyloidogenic processing, and disease progression, and suggest that inhibitors targeting the p75NTR transmembrane domain may be an effective therapeutic strategy in AD.
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Affiliation(s)
- Chenju Yi
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
- Present address:
The Seventh Affiliated Hospital of Sun Yat‐Sen UniversityShenzhenChina
| | - Ket Yin Goh
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
| | - Lik‐Wei Wong
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
| | - Ajeena Ramanujan
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
| | - Kazuhiro Tanaka
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
| | - Sreedharan Sajikumar
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
| | - Carlos F. Ibáñez
- Department of PhysiologyNational University of SingaporeSingapore CitySingapore
- Life Sciences InstituteNational University of SingaporeSingapore CitySingapore
- Department of NeuroscienceKarolinska InstituteStockholmSweden
- Stellenbosch Institute for Advanced StudyWallenberg Research Centre at Stellenbosch UniversityStellenboschSouth Africa
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Xiang R, Fan LL, Huang H, Chen YQ, He W, Guo S, Li JJ, Jin JY, Du R, Yan R, Xia K. Increased Reticulon 3 (RTN3) Leads to Obesity and Hypertriglyceridemia by Interacting With Heat Shock Protein Family A (Hsp70) Member 5 (HSPA5). Circulation 2019; 138:1828-1838. [PMID: 29716941 DOI: 10.1161/circulationaha.117.030718] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Reticulon 3 (RTN3) is an endoplasmic reticulum protein that has previously been shown to play a role in neurodegenerative diseases, but little is known about its role in lipid metabolism. METHODS Obese patients (n=149), hypertriglyceridemic patients (n=343), and healthy control subjects (n=84) were enrolled to assess their levels of RTN3. To explore the pathophysiological roles of RTN3 in the control of lipid metabolism, we used transgenic mice overexpressing the wild-type human RTN3 gene, the RTN3-null transgenic mouse model, and multiple Caenorhabditis legans strains for molecular characterization. The underlying mechanisms were studied with 3T3L1 cell cultures in vitro. RESULTS We report that overexpressed RTN3 in mice induces obesity and higher accumulation of triglycerides. Increased RTN3 expression is also found in patients with obesity and hypertriglyceridemia. We reveal that RTN3 plays critical roles in regulating the biosynthesis and storage of triglycerides and in controlling lipid droplet expansion. Mechanistically, RTN3 regulates these events through its interactions with heat shock protein family A (Hsp70) member 5, and this enhanced interaction increases sterol regulatory element-binding protein 1c and AMP-activated kinase activity. CONCLUSIONS This study provides evidence for a role of RTN3 in inducing obesity and triglyceride accumulation and suggests that inhibiting the expression of RTN3 in fat tissue may be a novel therapeutic approach to treat obesity and hypertriglyceridemia.
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Affiliation(s)
- Rong Xiang
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Liang-Liang Fan
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Hao Huang
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Ya-Qin Chen
- Department of Cardiology, Second Xiangya Hospital of Central South University, Changsha, China (Y.-q.C.)
| | - Wanxia He
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, OH (W.H., R.Y.)
| | - Shuai Guo
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Jing-Jing Li
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Jie-Yuan Jin
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Ran Du
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
| | - Riqiang Yan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, OH (W.H., R.Y.)
| | - Kun Xia
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China (R.X., L.-l.F., H.H., S.G., J.-J.L., J.-y.J., R.D., K.X.)
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Jackson TC, Kochanek PM. A New Vision for Therapeutic Hypothermia in the Era of Targeted Temperature Management: A Speculative Synthesis. Ther Hypothermia Temp Manag 2019; 9:13-47. [PMID: 30802174 PMCID: PMC6434603 DOI: 10.1089/ther.2019.0001] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Three decades of animal studies have reproducibly shown that hypothermia is profoundly cerebroprotective during or after a central nervous system (CNS) insult. The success of hypothermia in preclinical acute brain injury has not only fostered continued interest in research on the classic secondary injury mechanisms that are prevented or blunted by hypothermia but has also sparked a surge of new interest in elucidating beneficial signaling molecules that are increased by cooling. Ironically, while research into cold-induced neuroprotection is enjoying newfound interest in chronic neurodegenerative disease, conversely, the scope of the utility of therapeutic hypothermia (TH) across the field of acute brain injury is somewhat controversial and remains to be fully defined. This has led to the era of Targeted Temperature Management, which emphasizes a wider range of temperatures (33–36°C) showing benefit in acute brain injury. In this comprehensive review, we focus on our current understandings of the novel neuroprotective mechanisms activated by TH, and discuss the critical importance of developmental age germane to its clinical efficacy. We review emerging data on four cold stress hormones and three cold shock proteins that have generated new interest in hypothermia in the field of CNS injury, to create a framework for new frontiers in TH research. We make the case that further elucidation of novel cold responsive pathways might lead to major breakthroughs in the treatment of acute brain injury, chronic neurological diseases, and have broad potential implications for medicines of the distant future, including scenarios such as the prevention of adverse effects of long-duration spaceflight, among others. Finally, we introduce several new phrases that readily summarize the essence of the major concepts outlined by this review—namely, Ultramild Hypothermia, the “Responsivity of Cold Stress Pathways,” and “Hypothermia in a Syringe.”
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Affiliation(s)
- Travis C Jackson
- 1 John G. Rangos Research Center, UPMC Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania.,2 Department of Critical Care Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania
| | - Patrick M Kochanek
- 1 John G. Rangos Research Center, UPMC Children's Hospital of Pittsburgh, Safar Center for Resuscitation Research, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania.,2 Department of Critical Care Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania
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10
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Identification of rare RTN3 variants in Alzheimer's disease in Han Chinese. Hum Genet 2018; 137:141-150. [PMID: 29356939 DOI: 10.1007/s00439-018-1868-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/15/2018] [Indexed: 11/27/2022]
Abstract
Reticulon 3 (RTN3) is a neuronally-expressed reticulon family protein that was previously shown to negatively regulate BACE1, a protease that is required for the generation of β-amyloid peptides (Aβ) from amyloid precursor protein. Despite biochemical and morphological evidence that supports a role of RTN3 in the formation of neuritic amyloid plaques, no systematic analyses of RTN3 mutations in patients with Alzheimer's disease (AD) have yet been reported. RTN3 were targeted sequenced in 154 sporadic early-onset and 285 late-onset AD patients. Luciferase reporter assay and kymographs were performed to analysis the expression of RNT3 and BACE1-RFP particle mobility on cells transfected with wild-type or variants RTN3 constructs. We identified heterozygous variants such as c.-8G > T, c.17C > A, c.42C > T, and c.116C > T from patients in the early-onset AD group and c.-8G > T, c.17C > A, from patients in the late-onset AD group. Such variants of RTN3 were not observed in control individuals. Further biochemical studies show that the RTN3 c.-8G > T variant in the 5'-untranslated region appears to cause reduced expression of RTN3. The RTN3 c.116 C > T variant causes a change of codon T39 to M39 (T39 M). Overexpression of RTN3 T39 M in cultured neurons led to impaired axonal transport of BACE1. The variants found in this study are likely genetic modifiers for RTN3-mediated formation of neuritic plaques in AD.
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11
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Sharoar MG, Yan R. Effects of altered RTN3 expression on BACE1 activity and Alzheimer's neuritic plaques. Rev Neurosci 2018; 28:145-154. [PMID: 27883331 DOI: 10.1515/revneuro-2016-0054] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 09/20/2016] [Indexed: 12/15/2022]
Abstract
Reticulon 3 (RTN3), which is a member of the reticulon family of proteins, has a biochemical function of shaping tubular endoplasmic reticulum. RTN3 has also been found to interact with β-site amyloid precursor protein cleaving enzyme 1 (BACE1), which initiates the generation of β-amyloid peptides (Aβ) from amyloid precursor protein. Aβ is the major proteinaceous component in neuritic plaques, which constitute one of the major pathological features in brains of Alzheimer's disease (AD) patients. Mice deficient in or overexpressing RTN3 have altered amyloid deposition through effects on BACE1 expression and activity. In this review, we will summarize the current findings concerning the role of RTN3 in AD pathogenesis and demonstrate that RTN3 protein levels act as age-dependent modulators of BACE1 activity and Aβ deposition during the pathogenic progression of AD.
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12
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Yi C, Ezan P, Fernández P, Schmitt J, Sáez JC, Giaume C, Koulakoff A. Inhibition of glial hemichannels by boldine treatment reduces neuronal suffering in a murine model of Alzheimer's disease. Glia 2017; 65:1607-1625. [PMID: 28703353 DOI: 10.1002/glia.23182] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/04/2017] [Accepted: 05/30/2017] [Indexed: 01/06/2023]
Abstract
The contribution of reactive gliosis to the pathological phenotype of Alzheimer's disease (AD) opened the way for therapeutic strategies targeting glial cells instead of neurons. In such context, connexin hemichannels were proposed recently as potential targets since neuronal suffering is alleviated when connexin expression is genetically suppressed in astrocytes of a murine model of AD. Here, we show that boldine, an alkaloid from the boldo tree, inhibited hemichannel activity in astrocytes and microglia without affecting gap junctional communication in culture and acute hippocampal slices. Long-term oral administration of boldine in AD mice prevented the increase in glial hemichannel activity, astrocytic Ca2+ signal, ATP and glutamate release and alleviated hippocampal neuronal suffering. These findings highlight the important pathological role of hemichannels in AD mice. The neuroprotective effect of boldine treatment might provide the basis for future pharmacological strategies that target glial hemichannels to reduce neuronal damage in neurodegenerative diseases.
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Affiliation(s)
- Chenju Yi
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, PSL Research University, Paris, 75005, France
| | - Pascal Ezan
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, PSL Research University, Paris, 75005, France
| | - Paola Fernández
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencias de Valparaíso, Valparaíso, Chile
| | - Julien Schmitt
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine, Institut de Biologie Paris Seine (NPS-IBPS), Cerebellum Navigation and Memory team (CeZaMe), Paris, 75005, France
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencias de Valparaíso, Valparaíso, Chile
| | - Christian Giaume
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, PSL Research University, Paris, 75005, France
| | - Annette Koulakoff
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, PSL Research University, Paris, 75005, France
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13
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Sharoar MG, Shi Q, Ge Y, He W, Hu X, Perry G, Zhu X, Yan R. Dysfunctional tubular endoplasmic reticulum constitutes a pathological feature of Alzheimer's disease. Mol Psychiatry 2016; 21:1263-71. [PMID: 26619807 PMCID: PMC4887420 DOI: 10.1038/mp.2015.181] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 09/11/2015] [Accepted: 09/24/2015] [Indexed: 12/27/2022]
Abstract
Pathological features in Alzheimer's brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from Alzheimer's disease (AD) brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains.
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Affiliation(s)
- Md. Golam Sharoar
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - Qi Shi
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - Yingying Ge
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - Wanxia He
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - Xiangyou Hu
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - George Perry
- The University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249
| | - Xiongwei Zhu
- Department of Pathology, Case Western University School of Medicine, Cleveland, OH
| | - Riqiang Yan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
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14
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Astroglial connexin43 contributes to neuronal suffering in a mouse model of Alzheimer's disease. Cell Death Differ 2016; 23:1691-701. [PMID: 27391799 DOI: 10.1038/cdd.2016.63] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/19/2016] [Accepted: 05/25/2016] [Indexed: 01/15/2023] Open
Abstract
In Alzheimer's disease (AD), astrocyte properties are modified but their involvement in this pathology is only beginning to be appreciated. The expression of connexins, proteins forming gap junction channels and hemichannels, is increased in astrocytes contacting amyloid plaques in brains of AD patients and APP/PS1 mice. The consequences on their channel functions was investigated in a murine model of familial AD, the APPswe/PS1dE9 mice. Whereas gap junctional communication was not affected, we revealed that hemichannels were activated in astrocytes of acute hippocampal slices containing Aβ plaques. Such hemichannel activity was detected in all astrocytes, whatever their distance from amyloid plaques, but with an enhanced activity in the reactive astrocytes contacting amyloid plaques. Connexin43 was the main hemichannel contributor, however, a minor pannexin1 component was also identified in the subpopulation of reactive astrocytes in direct contact with plaques. Distinct regulatory pathways are involved in connexin and pannexin hemichannel activation. Inflammation triggered pannexin hemichannel activity, whereas connexin43 hemichannels were activated by the increase in resting calcium level of astrocytes. Importantly, hemichannel activation led to the release of ATP and glutamate that contributed to maintain a high calcium level in astrocytes placing them in the center of a vicious circle. The astroglial targeted connexin43 gene knocking-out in APPswe/PS1dE9 mice allowed to diminish gliotransmitter release and to alleviate neuronal damages, reducing oxidative stress and neuritic dystrophies in hippocampal neurons associated to plaques. Altogether, these data highlight the importance of astroglial hemichannels in AD and suggest that blocking astroglial hemichannel activity in astrocytes could represent an alternative therapeutic strategy in AD.
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15
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Abstract
Reticulon 3 (RTN3) has previously been shown to interact with BACE1 and negatively regulate BACE1 activity. To what extent RTN3 deficiency affects BACE1 activity is an intriguing question. In this study, we aimed to address this by generating RTN3-null mice. Mice with complete deficiency of RTN3 grow normally and have no obviously discernible phenotypes. Morphological analyses of RTN3-null mice showed no significant alterations in cellular structure, although RTN3 is recognized as a protein contributing to the shaping of tubular endoplasmic reticulum. Biochemical analysis revealed that RTN3 deficiency increased protein levels of BACE1. This elevation of BACE1 levels correlated with enhanced processing of amyloid precursor protein at the β-secretase site. We also demonstrated that RTN3 deficiency in Alzheimer's mouse models facilitates amyloid deposition, further supporting an in vivo role of RTN3 in the regulation of BACE1 activity. Since it has been shown that RTN3 monomer is reduced in brains of Alzheimer's patients, our results suggest that long-lasting reduction of RTN3 levels has adverse effects on BACE1 activity and may contribute to Alzheimer's pathogenesis.
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16
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Yoon SY, Choi JU, Cho MH, Yang KM, Ha H, Chung IJ, Cho GS, Kim DH. α-secretase cleaved amyloid precursor protein (APP) accumulates in cholinergic dystrophic neurites in normal, aged hippocampus. Neuropathol Appl Neurobiol 2014; 39:800-16. [PMID: 23414335 DOI: 10.1111/nan.12032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 01/31/2013] [Indexed: 12/17/2022]
Abstract
AIMS Dystrophic neurites are associated with β-amyloid (Aβ) plaques in the brains of Alzheimer's disease (AD) patients and are also found in some specific areas of normal, aged brains. This study assessed the molecular characteristics of dystrophic neurites in normal ageing and its difference from AD. METHODS We compared the dystrophic neurites in normal aged human brains (age 20-70 years) and AD brains (Braak stage 4-6) by immunostaining against ChAT, synaptophysin, γ-tubulin, cathepsin-D, Aβ1-16, Aβ17-24, amyloid precursor protein (APP)-CT695 and APP-NT. We then tested the reproducibility in C57BL/6 mice neurone cultures. RESULTS In normal, aged mice and humans, we found an increase in clustered dystrophic neurites of cholinergic neurones in CA1 regions of the hippocampus and layer II and III regions of the entorhinal cortex, which are the major and earliest affected areas in AD. These dystrophic neurites showed accumulation of sAPPα peptides cleaved from the amyloid precursor protein by α-secretase rather than Aβ or C-terminal fragments. In contrast, Aβ and APP-CTFs accumulated in the dystrophic neurites in and around Aβ plaques of AD patients. Several experiments suggested that the accumulation of sAPPα resulted from ageing-related proteasomal dysfunction. CONCLUSIONS Ageing-associated impairment of the proteasomal system and accumulation of sAPPα at cholinergic neurites in specific areas of brain regions associated with memory could be associated with the normal decline of memory in aged individuals. In addition, these age-related changes might be the most vulnerable targets of pathological insults that result in pathological accumulation of Aβ and/or APP-CTFs and lead to neurodegenerative conditions such as AD.
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Affiliation(s)
- S-Y Yoon
- Department of Anatomy and Cell Biology, Cell Dysfunction Research Center (CDRC), Bio-Medical Institute of Technology (BMIT), University of Ulsan College of Medicine, Seoul, Korea
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17
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Ramani B, Harris GM, Huang R, Seki T, Murphy GG, Costa MDC, Fischer S, Saunders TL, Xia G, McEachin RC, Paulson HL. A knockin mouse model of spinocerebellar ataxia type 3 exhibits prominent aggregate pathology and aberrant splicing of the disease gene transcript. Hum Mol Genet 2014; 24:1211-24. [PMID: 25320121 DOI: 10.1093/hmg/ddu532] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Polyglutamine diseases, including spinocerebellar ataxia type 3 (SCA3), are caused by CAG repeat expansions that encode abnormally long glutamine repeats in the respective disease proteins. While the mechanisms underlying neurodegeneration remain uncertain, evidence supports a proteotoxic role for the mutant protein dictated in part by the specific genetic and protein context. To further define pathogenic mechanisms in SCA3, we generated a mouse model in which a CAG expansion of 82 repeats was inserted into the murine locus by homologous recombination. SCA3 knockin mice exhibit region-specific aggregate pathology marked by intranuclear accumulation of the mutant Atxn3 protein, abundant nuclear inclusions and, in select brain regions, extranuclear aggregates localized to neuritic processes. Knockin mice also display altered splicing of the disease gene, promoting expression of an alternative isoform in which the intron immediately downstream of the CAG repeat is retained. In an independent mouse model expressing the full human ATXN3 disease gene, expression of this alternatively spliced transcript is also enhanced. These results, together with recent findings in other polyglutamine diseases, suggest that CAG repeat expansions can promote aberrant splicing to produce potentially more aggregate-prone isoforms of the disease proteins. This report of a SCA3 knockin mouse expands the repertoire of existing models of SCA3, and underscores the potential contribution of alternative splicing to disease pathogenesis in SCA3 and other polyglutamine disorders.
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Affiliation(s)
- Biswarathan Ramani
- Department of Neurology, Medical Scientist Training Program and Neuroscience Graduate Program
| | - Ginny M Harris
- Medical Scientist Training and Cellular and Molecular Biology Graduate Programs, University of Iowa College of Medicine, IA, USA
| | | | | | | | | | | | | | - Guangbin Xia
- Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Richard C McEachin
- Department of Computational Medicine & Bioinformatics, University of Michigan, MI, USA
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18
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Deng M, He W, Tan Y, Han H, Hu X, Xia K, Zhang Z, Yan R. Increased expression of reticulon 3 in neurons leads to reduced axonal transport of β site amyloid precursor protein-cleaving enzyme 1. J Biol Chem 2013; 288:30236-30245. [PMID: 24005676 DOI: 10.1074/jbc.m113.480079] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACE1 is the sole enzyme responsible for cleaving amyloid precursor protein at the β-secretase site, and this cleavage initiates the generation of β-amyloid peptide (Aβ). Because amyloid precursor protein is predominantly expressed by neurons and deposition of Aβ aggregates in the human brain is highly correlated with the Aβ released at axonal terminals, we focused our investigation of BACE1 localization on the neuritic region. We show that BACE1 was not only enriched in the late Golgi, trans-Golgi network, and early endosomes but also in both axons and dendrites. BACE1 was colocalized with the presynaptic vesicle marker synaptophysin, indicating the presence of BACE1 in synapses. Because the excessive release of Aβ from synapses is attributable to an increase in amyloid deposition, we further explored whether the presence of BACE1 in synapses was regulated by reticulon 3 (RTN3), a protein identified previously as a negative regulator of BACE1. We found that RTN3 is not only localized in the endoplasmic reticulum but also in neuritic regions where no endoplasmic reticulum-shaping proteins are detected, implicating additional functions of RTN3 in neurons. Coexpression of RTN3 with BACE1 in cultured neurons was sufficient to reduce colocalization of BACE1 with synaptophysin. This reduction correlated with decreased anterograde transport of BACE1 in axons in response to overexpressed RTN3. Our results in this study suggest that altered RTN3 levels can impact the axonal transport of BACE1 and demonstrate that reducing axonal transport of BACE1 in axons is a viable strategy for decreasing BACE1 in axonal terminals and, perhaps, reducing amyloid deposition.
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Affiliation(s)
- Minzi Deng
- From the State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan 410078, China and
| | - Wanxia He
- the Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Ya Tan
- From the State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan 410078, China and
| | - Hailong Han
- From the State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan 410078, China and
| | - Xiangyou Hu
- the Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Kun Xia
- From the State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan 410078, China and
| | - Zhuohua Zhang
- From the State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan 410078, China and.
| | - Riqiang Yan
- the Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195.
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19
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The Alzheimer's β-secretase BACE1 localizes to normal presynaptic terminals and to dystrophic presynaptic terminals surrounding amyloid plaques. Acta Neuropathol 2013; 126:329-52. [PMID: 23820808 PMCID: PMC3753469 DOI: 10.1007/s00401-013-1152-3] [Citation(s) in RCA: 179] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 06/20/2013] [Indexed: 01/18/2023]
Abstract
β-Site amyloid precursor protein (APP) cleaving enzyme-1 (BACE1) is the β-secretase that initiates Aβ production in Alzheimer’s disease (AD). BACE1 levels are increased in AD, which could contribute to pathogenesis, yet the mechanism of BACE1 elevation is unclear. Furthermore, the normal function of BACE1 is poorly understood. We localized BACE1 in the brain at both the light and electron microscopic levels to gain insight into normal and pathophysiologic roles of BACE1 in health and AD, respectively. Our findings provide the first ultrastructural evidence that BACE1 localizes to vesicles (likely endosomes) in normal hippocampal mossy fiber terminals of both non-transgenic and APP transgenic (5XFAD) mouse brains. In some instances, BACE1-positive vesicles were located near active zones, implying a function for BACE1 at the synapse. In addition, BACE1 accumulated in swollen dystrophic autophagosome-poor presynaptic terminals surrounding amyloid plaques in 5XFAD cortex and hippocampus. Importantly, accumulations of BACE1 and APP co-localized in presynaptic dystrophies, implying increased BACE1 processing of APP in peri-plaque regions. In primary cortical neuron cultures, treatment with the lysosomal protease inhibitor leupeptin caused BACE1 levels to increase; however, exposure of neurons to the autophagy inducer trehalose did not reduce BACE1 levels. This suggests that BACE1 is degraded by lysosomes but not by autophagy. Our results imply that BACE1 elevation in AD could be linked to decreased lysosomal degradation of BACE1 within dystrophic presynaptic terminals. Elevated BACE1 and APP levels in plaque-associated presynaptic dystrophies could increase local peri-plaque Aβ generation and accelerate amyloid plaque growth in AD.
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Shi Q, Prior M, Zhou X, Tang X, He W, Hu X, Yan R. Preventing formation of reticulon 3 immunoreactive dystrophic neurites improves cognitive function in mice. J Neurosci 2013; 33:3059-66. [PMID: 23407961 PMCID: PMC3711383 DOI: 10.1523/jneurosci.2445-12.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Revised: 11/27/2012] [Accepted: 12/17/2012] [Indexed: 01/11/2023] Open
Abstract
Neuritic dystrophy is one of the important pathological features associated with amyloid plaques in Alzheimer's disease (AD) and age-dependent neuronal dysfunctions. We reported previously that reticulon-3 (RTN3) immunoreactive dystrophic neurites (RIDNs) are abundantly present in the hippocampus of AD patients, in AD mouse models, and in aged wild-type mice. Transgenic mice overexpressing the human RTN3 transgene spontaneously develop RIDNs in their hippocampi, and the formation of RIDNs correlates with the appearance of RTN3 aggregation. To further elucidate whether the formation of RIDNs is reversible, we generated transgenic mice expressing wild-type human RTN3 under the control of a tetracycline-responsive promoter. Treatment with doxycycline for 2 months effectively turned off expression of the human RTN3 transgene, confirming the inducible nature of the system. However, the formation of hippocampal RIDNs was dependent on whether the transgene was turned off before or after the formation of RTN3 aggregates. When transgenic human RTN3 expression was turned off at young age, formation of RIDNs was essentially eliminated compared with the vehicle-treated transgenic mice. More importantly, a fear conditioning study demonstrated that contextual associative learning and memory in inducible transgenic mice was improved if the density of RIDNs was lowered. Additional mechanistic study suggested that a reduction in BDNF levels in transgenic mice might contribute to the reduced learning and memory in transgenic mice overexpressing RTN3. Hence, we conclude that age-dependent RIDNs cannot be effectively cleared once they have formed, and we postulate that successful prevention of RIDN formation should be initiated before RTN3 aggregation.
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Affiliation(s)
- Qi Shi
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Marguerite Prior
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Xiangdong Zhou
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Xiaoying Tang
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Wanxia He
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Xiangyou Hu
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Riqiang Yan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195
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Pernet V, Schwab ME. The role of Nogo-A in axonal plasticity, regrowth and repair. Cell Tissue Res 2012; 349:97-104. [PMID: 22588543 DOI: 10.1007/s00441-012-1432-6] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/05/2012] [Indexed: 12/13/2022]
Abstract
Axonal damage leads to permanent deficits in the adult central nervous system (CNS) not only because of the weak intrinsic ability of adult neurons to activate their growth program but importantly also because of the presence of specific growth inhibitors in the CNS tissue and the environment of the damaged axons. The well-studied myelin-derived protein Nogo-A is involved in various cellular and molecular events contributing to the failure of CNS axons to regrow and reconnect after transection. Recent studies have shown that, by acting in a negative way on the cytoskeleton and on the growth program of axotomized neurons, Nogo-A exerts fast and chronic inhibitory effects on neurite outgrowth. On the other hand, the blockade of Nogo-A results in a marked enhancement of compensatory and regenerative axonal extension in vivo; this enhancement is often paralleled by significant functional recovery, for example, of locomotion or skilled forelimb reaching after spinal cord or stroke lesions in rats and monkeys. Surprisingly, the blockade of Nogo-A or its receptor NgR in the hippocampus has recently been demonstrated to enhance long-term potentiation. A role of Nogo-A in synaptic plasticity/stability might therefore represent an additional, new and important aspect of CNS circuit remodeling. Function-blocking anti-Nogo-A antibodies are currently being tested in a clinical trial for improved outcome after spinal cord injury.
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Affiliation(s)
- Vincent Pernet
- Brain Research Institute, University of Zürich/ETH, Department of Health Sciences and Technology ETH Zürich, Winterthurerstrasse 190, Room 55J34a, 8057 Zürich, Switzerland.
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22
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The basal forebrain cholinergic system in aging and dementia. Rescuing cholinergic neurons from neurotoxic amyloid-β42 with memantine. Behav Brain Res 2011; 221:594-603. [DOI: 10.1016/j.bbr.2010.05.033] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 05/19/2010] [Indexed: 01/19/2023]
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23
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Heath JE, Siedlak SL, Zhu X, Lee HG, Thakur A, Yan R, Perry G, Smith MA, Castellani RJ. Widespread distribution of reticulon-3 in various neurodegenerative diseases. Neuropathology 2011; 30:574-9. [PMID: 20374499 DOI: 10.1111/j.1440-1789.2010.01107.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reticulons are a group of membrane-bound proteins involved in diverse cellular functions, and are suggested to act as inhibitors of β-secretase enzyme 1 (BACE1) activity that cleaves amyloid precursor protein. Reticulons are known to accumulate in the dystrophic neurites of Alzheimer's disease (AD), and studies have suggested that alterations in reticulons, such as increased aggregation, impair BACE1 binding, increasing amyloid-β production, and facilitating reticulon deposition in dystrophic neurites. To further characterize the cellular distribution of reticulon, we examined reticulon-3 expression in cases of AD, Parkinson's disease, and diffuse Lewy body disease. A more widespread cellular distribution of reticulon-3 was noted than in previous reports, including deposits in dystrophic neurites, neuropil threads, granulovacuolar degeneration, glial cells, morphologically normal neurons in both hippocampal pyramidal cell layer and cerebral neocortex, and specifically neurofibrillary tangles and Lewy bodies. These results are compatible with reticulon alterations as nonspecific downstream stress responses, consistent with its expression during periods of endoplasmic reticulum stress. This emphasizes the increasing recognition that much of the AD pathological spectrum represents a response to the disease rather than cause, and emphasizes the importance of examining upstream processes, such as oxidative stress, that have functional effects prior to the onset of structural alterations.
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Affiliation(s)
- Jonathon E Heath
- Department of Pathology, University of Maryland, Baltimore, Maryland, USA
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Prior M, Shi Q, Hu X, He W, Levey A, Yan R. RTN/Nogo in forming Alzheimer's neuritic plaques. Neurosci Biobehav Rev 2010; 34:1201-6. [PMID: 20144652 PMCID: PMC2888855 DOI: 10.1016/j.neubiorev.2010.01.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/27/2010] [Accepted: 01/31/2010] [Indexed: 12/18/2022]
Abstract
One of the pathological hallmarks in brains of patients with Alzheimer's disease (AD) is the presence of neuritic plaques, in which amyloid deposits are surrounded by reactive gliosis and dystrophic neurites. Within neuritic plaques, reticulon 3 (RTN3), a homolog of Nogo protein, appears to regulate the formation of both amyloid deposition via negative modulation of BACE1 activity and dystrophic neurites via the formation of RTN3 aggregates. Transgenic mice over-expressing RTN3, but not the other known markers of dystrophic neurites in AD brain, spontaneously develop RTN3-immunoreactive dystrophic neurites. The presence of dystrophic neurites impairs cognition. Blocking abnormal RTN3 aggregation will increase the available RTN3 monomer and is therefore a promising therapeutic strategy for enhancing cognitive function in AD patients.
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Affiliation(s)
- Marguerite Prior
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Qi Shi
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Xiangyou Hu
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Wanxia He
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
| | - Allan Levey
- Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Riqiang Yan
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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Protein disulfide isomerase and the endoplasmic reticulum in amyotrophic lateral sclerosis. J Neurosci 2010; 30:3865-7. [PMID: 20237255 DOI: 10.1523/jneurosci.0408-10.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Reduced amyloid deposition in mice overexpressing RTN3 is adversely affected by preformed dystrophic neurites. J Neurosci 2009; 29:9163-73. [PMID: 19625507 DOI: 10.1523/jneurosci.5741-08.2009] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Reticulon 3 (RTN3) was initially identified as a negative modulator of BACE1, an enzyme that cleaves amyloid precursor protein (APP) to release beta-amyloid peptide. Interestingly, RTN3 can also form aggregates after accumulation, and increased RTN3 aggregation correlates with the formation of RTN3 immunoreactive dystrophic neurites (RIDNs) in brains of Alzheimer's cases. Transgenic mice expressing RTN3 alone develop RIDNs in their hippocampus but not in their cortex. To determine the in vivo effects of RTN3 and preformed RIDNs on amyloid deposition, we crossed bitransgenic mice expressing APP and presenilin 1 (PS1) mutations with mice overexpressing RTN3. We found that amyloid deposition in cortex, the hippocampal CA3 region, and dentate gyrus was significantly reduced in triple transgenic mice compared with bitransgenic controls. However, reduction of amyloid deposition in the hippocampal CA1 region, where RIDNs predominantly formed before amyloid deposition, was less significant. Hence, preformed RTN3 aggregates in RIDNs clearly offset the negative modulation of BACE1 activity by RTN3. Furthermore, our study indicates that the increased expression of RTN3 could result in an alteration of BACE1 intracellular trafficking by retaining more BACE1 in the endoplasmic reticulum compartment where cleavage of APP by BACE1 is less favored. Our results suggest that inhibition of RTN3 aggregation is likely to be beneficial by reducing both amyloid deposition and the formation RIDNs.
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