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Lin L, Basu R, Chatterjee D, Templin AT, Flak JN, Johnson TS. Disease-associated astrocytes and microglia markers are upregulated in mice fed high fat diet. Sci Rep 2023; 13:12919. [PMID: 37558676 PMCID: PMC10412627 DOI: 10.1038/s41598-023-39890-0] [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: 05/12/2023] [Accepted: 08/01/2023] [Indexed: 08/11/2023] Open
Abstract
High-fat diet (HFD) is associated with Alzheimer's disease (AD) and type 2 diabetes risk, which share features such as insulin resistance and amylin deposition. We examined gene expression associated with astrocytes and microglia since dysfunction of these cell types is implicated in AD pathogenesis. We hypothesize gene expression changes in disease-associated astrocytes (DAA), disease-associated microglia and human Alzheimer's microglia exist in diabetic and obese individuals before AD development. By analyzing bulk RNA-sequencing (RNA-seq) data generated from brains of mice fed HFD and humans with AD, 11 overlapping AD-associated differentially expressed genes were identified, including Kcnj2, C4b and Ddr1, which are upregulated in response to both HFD and AD. Analysis of single cell RNA-seq (scRNA-seq) data indicated C4b is astrocyte specific. Spatial transcriptomics (ST) revealed C4b colocalizes with Gfad, a known astrocyte marker, and the colocalization of C4b expressing cells with Gad2 expressing cells, i.e., GABAergic neurons, in mouse brain. There also exists a positive correlation between C4b and Gad2 expression in ST indicating a potential interaction between DAA and GABAergic neurons. These findings provide novel links between the pathogenesis of obesity, diabetes and AD and identify C4b as a potential early marker for AD in obese or diabetic individuals.
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Affiliation(s)
- Li Lin
- Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Rashmita Basu
- Indiana Biosciences Research Institute, Indianapolis, IN, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Debolina Chatterjee
- Department of Biostatistics and Health Data Science, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Andrew T Templin
- Indiana Biosciences Research Institute, Indianapolis, IN, USA
- Division of Endocrinology, Department of Medicine, Richard L. Roudebush VA Medical Center, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jonathan N Flak
- Indiana Biosciences Research Institute, Indianapolis, IN, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Travis S Johnson
- Indiana Biosciences Research Institute, Indianapolis, IN, USA.
- Department of Biostatistics and Health Data Science, Indiana University School of Medicine, Indianapolis, IN, USA.
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Tian J, Stucky CS, Wang T, Muma NA, Johnson M, Du H. Mitochondrial Dysfunction Links to Impaired Hippocampal Serotonin Release in a Mouse Model of Alzheimer's Disease. J Alzheimers Dis 2023; 93:605-619. [PMID: 37066917 PMCID: PMC10416312 DOI: 10.3233/jad-230072] [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: 04/18/2023]
Abstract
BACKGROUND Deprivation of extracellular serotonin has been linked to cognitive decline and neuropsychiatric disturbances in Alzheimer's disease (AD). However, despite degeneration of serotonin-producing neurons, whether serotonin release is affected in AD-sensitive brain regions is unknown. OBJECTIVE This study investigated the impact of mitochondrial dysfunction in decreased hippocampal serotonin release in AD amyloidosis mouse model 5xFAD mice. METHODS Electrochemical assays were applied to examine hippocampal serotonin release. We also employed multidisciplinary techniques to determine the role of oligomeric amyloid-β (Aβ) in hippocampal mitochondrial deficits and serotonin release deficiency. RESULTS 5xFAD mice exhibited serotonin release decrease and relatively moderate downregulation of serotonergic fiber density as well as serotonin content in the hippocampal region. Further experiments showed an inhibitory effect of oligomeric amyloid-β (Aβ) on hippocampal serotonin release without affecting the density of serotonergic fibers. Pharmaceutical uncoupling of mitochondrial oxidative phosphorylation (OXPHOS) disrupted hippocampal serotonin release in an ex vivo setting. This echoes the mitochondrial defects in serotonergic fibers in 5xFAD mice and oligomeric Aβ-challenged primary serotonergic neuron cultures and implicates a link between mitochondrial dysfunction and serotonin transmission defects in AD-relevant pathological settings. CONCLUSION The most parsimonious interpretation of our findings is that mitochondrial dysfunction is a phenotypic change of serotonergic neurons, which potentially plays a role in the development of serotonergic failure in AD-related conditions.
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Affiliation(s)
- Jing Tian
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | | | - Tienju Wang
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | - Nancy A. Muma
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | - Michael Johnson
- Department of Chemistry, University of Kansas, Lawrence, KS, USA
| | - Heng Du
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
- Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA
- Alzheimer’s Disease Center, University of Kansas Medical Center, Lawrence, KS, USA
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Qiu H, Weng Q. Screening of Crucial Differentially-Methylated/Expressed Genes for Alzheimer's Disease. Am J Alzheimers Dis Other Demen 2022; 37:15333175221116220. [PMID: 35848539 PMCID: PMC10624077 DOI: 10.1177/15333175221116220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: We aimed to make an integrated analysis of published transcriptome and DNA methylation dataset to ascertain the key differentially methylated and differentially expressed genes for Alzherimer's disease (AD). Methods: Two gene expression microarrays and 1 gene methylation microarray were downloaded for identification of differentially expressed genes and differentially methylated genes. Then, we used various biological information databases to annotate the functions of the differentially-methylated/expressed genes, and screen out key genes and important signaling pathways. Finally, we validate the differentially-methylated/expressed genes in the additional online datasets and in blood from AD patients.Results: A total of 8 hub hypomethylated-high expression genes were obtained, including Rac family small GTPase 2, FGR proto-oncogene, Src family tyrosine kinase, LYN proto-oncogene, Src family tyrosine kinase, protein kinase C delta, myosin IF, integrin subunit alpha 5, semaphorin 4D, and growth arrest specific protein 7. Some enriched signaling pathways of hypomethylated-high expression genes were identified, including regulation of actin cytoskeleton, chemokine signaling pathway, Fc gamma R-mediated phagocytosis, and axon guidance. Conclusion: Differentially-methylated/expressed genes are likely to be associated with AD.
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Affiliation(s)
- Haiyuan Qiu
- Internal Medicine Department, Ningbo Psychiatric Hospital, Ningbo, China
| | - Qiuyan Weng
- Neurolog Department, Affiliated Hospital of Medical School Ningbo University, Ningbo, China
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Khanal P, Hotulainen P. Dendritic Spine Initiation in Brain Development, Learning and Diseases and Impact of BAR-Domain Proteins. Cells 2021; 10:cells10092392. [PMID: 34572042 PMCID: PMC8468246 DOI: 10.3390/cells10092392] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 02/08/2023] Open
Abstract
Dendritic spines are small, bulbous protrusions along neuronal dendrites where most of the excitatory synapses are located. Dendritic spine density in normal human brain increases rapidly before and after birth achieving the highest density around 2-8 years. Density decreases during adolescence, reaching a stable level in adulthood. The changes in dendritic spines are considered structural correlates for synaptic plasticity as well as the basis of experience-dependent remodeling of neuronal circuits. Alterations in spine density correspond to aberrant brain function observed in various neurodevelopmental and neuropsychiatric disorders. Dendritic spine initiation affects spine density. In this review, we discuss the importance of spine initiation in brain development, learning, and potential complications resulting from altered spine initiation in neurological diseases. Current literature shows that two Bin Amphiphysin Rvs (BAR) domain-containing proteins, MIM/Mtss1 and SrGAP3, are involved in spine initiation. We review existing literature and open databases to discuss whether other BAR-domain proteins could also take part in spine initiation. Finally, we discuss the potential molecular mechanisms on how BAR-domain proteins could regulate spine initiation.
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Affiliation(s)
- Pushpa Khanal
- Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland;
- HiLIFE-Neuroscience Center, University of Helsinki, 00014 Helsinki, Finland
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, Tukholmankatu 8, 00290 Helsinki, Finland;
- Correspondence:
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Key Disease Mechanisms Linked to Alzheimer's Disease in the Entorhinal Cortex. Int J Mol Sci 2021; 22:ijms22083915. [PMID: 33920138 PMCID: PMC8069371 DOI: 10.3390/ijms22083915] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/05/2021] [Accepted: 04/07/2021] [Indexed: 02/06/2023] Open
Abstract
Alzheimer’s disease (AD) is a chronic, neurodegenerative brain disorder affecting millions of Americans that is expected to increase in incidence with the expanding aging population. Symptomatic AD patients show cognitive decline and often develop neuropsychiatric symptoms due to the accumulation of insoluble proteins that produce plaques and tangles seen in the brain at autopsy. Unexpectedly, some clinically normal individuals also show AD pathology in the brain at autopsy (asymptomatic AD, AsymAD). In this study, SWItchMiner software was used to identify key switch genes in the brain’s entorhinal cortex that lead to the development of AD or disease resilience. Seventy-two switch genes were identified that are differentially expressed in AD patients compared to healthy controls. These genes are involved in inflammation, platelet activation, and phospholipase D and estrogen signaling. Peroxisome proliferator-activated receptor γ (PPARG), zinc-finger transcription factor (YY1), sterol regulatory element-binding transcription factor 2 (SREBF2), and early growth response 1 (EGR1) were identified as transcription factors that potentially regulate switch genes in AD. Comparing AD patients to AsymAD individuals revealed 51 switch genes; PPARG as a potential regulator of these genes, and platelet activation and phospholipase D as critical signaling pathways. Chemical–protein interaction analysis revealed that valproic acid is a therapeutic agent that could prevent AD from progressing.
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Yao X, Cong S, Yan J, Risacher SL, Saykin AJ, Moore JH, Shen L. Regional imaging genetic enrichment analysis. Bioinformatics 2020; 36:2554-2560. [PMID: 31860065 DOI: 10.1093/bioinformatics/btz948] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/19/2019] [Accepted: 12/18/2019] [Indexed: 12/25/2022] Open
Abstract
MOTIVATION Brain imaging genetics aims to reveal genetic effects on brain phenotypes, where most studies examine phenotypes defined on anatomical or functional regions of interest (ROIs) given their biologically meaningful interpretation and modest dimensionality compared with voxelwise approaches. Typical ROI-level measures used in these studies are summary statistics from voxelwise measures in the region, without making full use of individual voxel signals. RESULTS In this article, we propose a flexible and powerful framework for mining regional imaging genetic associations via voxelwise enrichment analysis, which embraces the collective effect of weak voxel-level signals and integrates brain anatomical annotation information. Our proposed method achieves three goals at the same time: (i) increase the statistical power by substantially reducing the burden of multiple comparison correction; (ii) employ brain annotation information to enable biologically meaningful interpretation and (iii) make full use of fine-grained voxelwise signals. We demonstrate our method on an imaging genetic analysis using data from the Alzheimer's Disease Neuroimaging Initiative, where we assess the collective regional genetic effects of voxelwise FDG-positron emission tomography measures between 116 ROIs and 565 373 single-nucleotide polymorphisms. Compared with traditional ROI-wise and voxelwise approaches, our method identified 2946 novel imaging genetic associations in addition to 33 ones overlapping with the two benchmark methods. In particular, two newly reported variants were further supported by transcriptome evidences from region-specific expression analysis. This demonstrates the promise of the proposed method as a flexible and powerful framework for exploring imaging genetic effects on the brain. AVAILABILITY AND IMPLEMENTATION The R code and sample data are freely available at https://github.com/lshen/RIGEA. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Xiaohui Yao
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shan Cong
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jingwen Yan
- Department of BioHealth Informatics, Indiana University School of Informatics and Computing, Indiana University
| | - Shannon L Risacher
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Andrew J Saykin
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Jason H Moore
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Li Shen
- Department of Biostatistics, Epidemiology and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Bhupana JN, Huang BT, Liou GG, Calkins MJ, Lin-Chao S. Gas7 knockout affects PINK1 expression and mitochondrial dynamics in mouse cortical neurons. FASEB Bioadv 2020; 2:166-181. [PMID: 32161906 PMCID: PMC7059628 DOI: 10.1096/fba.2019-00091] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 11/21/2019] [Accepted: 12/31/2019] [Indexed: 11/11/2022] Open
Abstract
Dynamic fission and fusion events regulate mitochondrial shape, distribution, and rejuvenation, and proper control of these processes is essential for neuronal homeostasis. Here, we report that Gas7, a known cytoskeleton regulator, controls mitochondrial dynamics within neurons of the central nervous system. In this study, we generated an improved Gas7-knockout mouse and evaluated its mitochondrial phenotype. We first identified Gas7 in mitochondrial fractions from wild-type brain tissue, and observed Gas7 colocalization with mitochondria in primary cortical neurons. In Gas7-deficient brain tissue and neuronal cultures mitochondria were elongated with perinuclear clustering. These morphological abnormalities were associated with increased levels mitochondrial fusion proteins and increased PKA-dependent phosphorylation of Drp-1 in brain tissues, suggesting an imbalance of mitochondrial fusion and fission. Moreover, expression of mitochondrial quality control kinase, PINK1, and PINK1-specific phosphorylation of Mfn-2 (S442), Parkin (S65), and ubiquitin (S65) were all reduced in the knockout cells. Ectopic expression of Gas7 restored mitochondrial morphology and distribution, as well as PINK1 expression in Gas7-null cortical neurons. Collectively, our results introduce a novel role of mouse Gas7 in determining the dynamics, morphology, and intracellular distribution of neuronal mitochondria, which are expected to be required for normal neuronal function.
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Affiliation(s)
- Jagannatham Naidu Bhupana
- Molecular Cell Biology Taiwan International Graduate Program Institute of Molecular Biology Academia Sinica and Graduate Institute of Life Sciences National Defense Medical Center Taipei Taiwan.,Institute of Molecular Biology Academia Sinica Taipei Taiwan
| | - Bo-Tsang Huang
- Institute of Molecular Biology Academia Sinica Taipei Taiwan
| | - Gunn-Guang Liou
- Institute of Molecular Biology Academia Sinica Taipei Taiwan
| | - Marcus J Calkins
- Institute of Cellular and Organismic Biology Academia Sinica Taipei Taiwan
| | - Sue Lin-Chao
- Molecular Cell Biology Taiwan International Graduate Program Institute of Molecular Biology Academia Sinica and Graduate Institute of Life Sciences National Defense Medical Center Taipei Taiwan.,Institute of Molecular Biology Academia Sinica Taipei Taiwan
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8
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Wang MH, Chang B, Sun R, Hu I, Xia X, Wu WKK, Chong KC, Zee BCY. Stratified polygenic risk prediction model with application to CAGI bipolar disorder sequencing data. Hum Mutat 2017; 38:1235-1239. [PMID: 28419606 DOI: 10.1002/humu.23229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 03/13/2017] [Accepted: 04/04/2017] [Indexed: 01/31/2023]
Abstract
Genetic data consists of a wide range of marker types, including common, low-frequency, and rare variants. Multiple genetic markers and their interactions play central roles in the heritability of complex disease. In this study, we propose an algorithm that uses a stratified variable selection design by genetic architectures and interaction effects, achieved by a dataset-adaptive W-test. The polygenic sets in all strata were integrated to form a classification rule. The algorithm was applied to the Critical Assessment of Genome Interpretation 4 bipolar challenge sequencing data. The prediction accuracy was 60% using genetic markers on an independent test set. We found that epistasis among common genetic variants contributed most substantially to prediction precision. However, the sample size was not large enough to draw conclusions for the lack of predictability of low-frequency variants and their epistasis.
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Affiliation(s)
- Maggie Haitian Wang
- Division of Biostatistics and Centre for Clinical Research and Biostatistics, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, China.,CUHK Shenzhen Research Institute, Shenzhen, China
| | - Billy Chang
- Division of Biostatistics and Centre for Clinical Research and Biostatistics, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Rui Sun
- Division of Biostatistics and Centre for Clinical Research and Biostatistics, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, China.,CUHK Shenzhen Research Institute, Shenzhen, China
| | - Inchi Hu
- ISOM Department and Biomedical Engineering Division, The Hong Kong University of Science and Technology, Kowloon, Hong Kong SAR, China
| | - Xiaoxuan Xia
- Division of Biostatistics and Centre for Clinical Research and Biostatistics, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - William Ka Kei Wu
- Department of Anaethesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Ka Chun Chong
- Division of Biostatistics and Centre for Clinical Research and Biostatistics, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, China.,CUHK Shenzhen Research Institute, Shenzhen, China
| | - Benny Chung-Ying Zee
- Division of Biostatistics and Centre for Clinical Research and Biostatistics, JC School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, China.,CUHK Shenzhen Research Institute, Shenzhen, China
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Hung FC, Shih HY, Cheng YC, Chao CCK. Growth-Arrest-Specific 7 Gene Regulates Neural Crest Formation and Craniofacial Development in Zebrafish. Stem Cells Dev 2015; 24:2943-51. [PMID: 26414806 DOI: 10.1089/scd.2015.0146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Growth-arrest-specific 7 (Gas7) is preferentially expressed in the nervous system and plays an important role during neuritogenesis in vertebrates. We recently demonstrated that gas7 is highly expressed in zebrafish neurons, where it regulates neural development. The possibility that gas7 may also regulate the development of other tissues remains to be examined. In this study, we investigate the role of Gas7 in the development of craniofacial tissues. Knockdown of gas7 using morpholino oligomers produced abnormal phenotypes in neural crest (NC) cells and their derivatives. NC-derived cartilage maturation was altered in Gas7 morphants as revealed by aberrant sox9b and dlx2 expression, a phenotype that could be rescued by coinjection of gas7 mRNA. While rhombomere morphology remained normal in Gas7 morphants, we observed reduced expression of the prechondrogenic genes sox9b and dlx2 in cells populating the posterior pharyngeal arches, but the fundamental structure of pharyngeal arches was preserved. In addition, NC cell sublineages that migrate to form neurons, glial cells, and melanocytes were altered in Gas7 morphants as revealed by aberrant expression of neurod, foxd3, and mitfa, respectively. Development of NC progenitors was also examined in Gas7 morphants at 12 hpf, and we observed that the reduction of cell precursors in Gas7 morphants was due to increased apoptosis level. These results indicate that the formation of NC progenitors and derivatives depends on Gas7 expression. Our observations also suggest that Gas7 regulates the formation of NC derivatives constituting the internal tissues of pharyngeal arches, without affecting the fundamental structure of mesodermal-derived pharyngeal arches.
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Affiliation(s)
- Feng-Chun Hung
- 1 Department of Biochemistry and Molecular Biology, Chang Gung University , Taiwan, Republic of China
| | - Hung-Yu Shih
- 1 Department of Biochemistry and Molecular Biology, Chang Gung University , Taiwan, Republic of China .,2 Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taiwan, Republic of China
| | - Yi-Chuan Cheng
- 1 Department of Biochemistry and Molecular Biology, Chang Gung University , Taiwan, Republic of China .,2 Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taiwan, Republic of China .,3 Chang Gung Memorial Hospital , Taiwan, Republic of China
| | - Chuck C-K Chao
- 1 Department of Biochemistry and Molecular Biology, Chang Gung University , Taiwan, Republic of China .,2 Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University , Taiwan, Republic of China .,3 Chang Gung Memorial Hospital , Taiwan, Republic of China
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Gotoh A, Hidaka M, Hirose K, Uchida T. Gas7b (growth arrest specific protein 7b) regulates neuronal cell morphology by enhancing microtubule and actin filament assembly. J Biol Chem 2013; 288:34699-706. [PMID: 24151073 DOI: 10.1074/jbc.m113.513119] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neurons undergo several morphological changes as a part of normal neuron maturation process. Alzheimer disease is associated with increased neuroproliferation and impaired neuronal maturation. In this study, we demonstrated that Gas7b (growth arrest specific protein 7b) expression in a neuronal cell line, Neuro 2A, induces cell maturation by facilitating formation of dendrite-like processes and/or filopodia projections and that Gas7b co-localizes with neurite microtubules. Molecular analysis was performed to evaluate whether Gas7b associates with actin filaments and microtubules, and the data revealed two novel roles of Gas7b in neurite outgrowth: we showed that Gas7b enhances bundling of several microtubule filaments and connects microtubules with actin filaments. These results suggest that Gas7b governs neural cell morphogenesis by enhancing the coordination between actin filaments and microtubules. We conclude that lower neuronal Gas7b levels may impact Alzheimer disease progression.
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Affiliation(s)
- Aina Gotoh
- From the Molecular Enzymology, Department of Molecular Cell Science, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan and
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Atherton J, Houdusse A, Moores C. MAPping out distribution routes for kinesin couriers. Biol Cell 2013; 105:465-87. [PMID: 23796124 DOI: 10.1111/boc.201300012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 06/17/2013] [Indexed: 12/14/2022]
Abstract
In the crowded environment of eukaryotic cells, diffusion is an inefficient distribution mechanism for cellular components. Long-distance active transport is required and is performed by molecular motors including kinesins. Furthermore, in highly polarised, compartmentalised and plastic cells such as neurons, regulatory mechanisms are required to ensure appropriate spatio-temporal delivery of neuronal components. The kinesin machinery has diversified into a large number of kinesin motor proteins as well as adaptor proteins that are associated with subsets of cargo. However, many mechanisms contribute to the correct delivery of these cargos to their target domains. One mechanism is through motor recognition of sub-domain-specific microtubule (MT) tracks, sign-posted by different tubulin isoforms, tubulin post-translational modifications, tubulin GTPase activity and MT-associated proteins (MAPs). With neurons as a model system, a critical review of these regulatory mechanisms is presented here, with a particular focus on the emerging contribution of compartmentalised MAPs. Overall, we conclude that - especially for axonal cargo - alterations to the MT track can influence transport, although in vivo, it is likely that multiple track-based effects act synergistically to ensure accurate cargo distribution.
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Affiliation(s)
- Joseph Atherton
- Institute of Structural and Molecular Biology, Birkbeck College, London, WC1E 7HX, UK
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