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Deng T, Xie L, Xiaofang C, Zhang Z, Xiao Y, Peng Y, Yin L, Fu Y, Li X. ATM-Mediated translocation of RanBPM regulates DNA damage response by stabilizing p21 in non-small cell lung cancer cells. Cell Oncol (Dordr) 2024; 47:245-258. [PMID: 37676377 PMCID: PMC10899406 DOI: 10.1007/s13402-023-00866-x] [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] [Accepted: 08/23/2023] [Indexed: 09/08/2023] Open
Abstract
PURPOSE Platinum-based chemotherapy remains a standard-of-care for most patients with advanced non-small cell lung cancer (NSCLC). DNA damage response (DDR) induced by platinum or Etoposide activated a panel of cell cycle-regulatory proteins including p21 through p53 pathway. Previous studies have reported that RanBPM has been involved in various cellular processes such as DDR by interacting with multiple proteins. However, the underlying mechanism remains unclear. METHODS NSCLC tissue microarrays were used for assessing the expression of RanBPM by immunohistochemical staining. The roles of RanBPM in the DDR of NSCLC progression was examined in in vitro cell lines and in vivo animal models. The regulation of RanBPM on protein stability and ubiquitination levels were investigated by immunoblots and in vivo ubiquitylation assay. RESULTS The level of p21 or RanBPM is lower in NSCLC than non-malignant tissues and has a highly positive correlation. Mechanistically, RanBPM protein physically interacts with p21, and RanBPM deubiquitinates p21 by recruiting a deubiquitinase USP11 to maintain protein stability of p21. RanBPM silencing significantly decreased p21 protein level. Conversely, RanBPM overexpression led to the accumulation of endogenous p21 protein regardless of p53 status. Functionally, RanBPM regulates DDR in a p21-dependent manner. Furthermore, DNA damage significantly promoted the nuclear translocation of RanBPM protein through ATM signaling pathways. CONCLUSION RanBPM is a novel regulator of P21 protein stability, and plays a critical role in the regulation of DDR.
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Affiliation(s)
- Tanggang Deng
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China.
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China.
| | - Lin Xie
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China
| | - Chen Xiaofang
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
| | - Zhenbin Zhang
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yugang Xiao
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yuchong Peng
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China
| | - Linglong Yin
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yongming Fu
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China
| | - Xiong Li
- Center for Clinical Precision Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, 19 Nonglinxia Road, Yuexiu District, Guangzhou, Guangdong, China.
- Clinical Pharmacy, The First Affiliated Hospital, Guangdong Pharmaceutical University, Guangzhou, China.
- NMPA Key Laboratory for Technology Research and Evaluation of Pharmacovigilance, Guangdong Pharmaceutical University, Guangzhou, China.
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou, China.
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2
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Structural and Functional Insights into GID/CTLH E3 Ligase Complexes. Int J Mol Sci 2022; 23:ijms23115863. [PMID: 35682545 PMCID: PMC9180843 DOI: 10.3390/ijms23115863] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 11/29/2022] Open
Abstract
Multi-subunit E3 ligases facilitate ubiquitin transfer by coordinating various substrate receptor subunits with a single catalytic center. Small molecules inducing targeted protein degradation have exploited such complexes, proving successful as therapeutics against previously undruggable targets. The C-terminal to LisH (CTLH) complex, also called the glucose-induced degradation deficient (GID) complex, is a multi-subunit E3 ligase complex highly conserved from Saccharomyces cerevisiae to humans, with roles in fundamental pathways controlling homeostasis and development in several species. However, we are only beginning to understand its mechanistic basis. Here, we review the literature of the CTLH complex from all organisms and place previous findings on individual subunits into context with recent breakthroughs on its structure and function.
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de Pins B, Mendes T, Giralt A, Girault JA. The Non-receptor Tyrosine Kinase Pyk2 in Brain Function and Neurological and Psychiatric Diseases. Front Synaptic Neurosci 2021; 13:749001. [PMID: 34690733 PMCID: PMC8527176 DOI: 10.3389/fnsyn.2021.749001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/14/2021] [Indexed: 12/28/2022] Open
Abstract
Pyk2 is a non-receptor tyrosine kinase highly enriched in forebrain neurons. Pyk2 is closely related to focal adhesion kinase (FAK), which plays an important role in sensing cell contacts with extracellular matrix and other extracellular signals controlling adhesion and survival. Pyk2 shares some of FAK’s characteristics including recruitment of Src-family kinases after autophosphorylation, scaffolding by interacting with multiple partners, and activation of downstream signaling pathways. Pyk2, however, has the unique property to respond to increases in intracellular free Ca2+, which triggers its autophosphorylation following stimulation of various receptors including glutamate NMDA receptors. Pyk2 is dephosphorylated by the striatal-enriched phosphatase (STEP) that is highly expressed in the same neuronal populations. Pyk2 localization in neurons is dynamic, and altered following stimulation, with post-synaptic and nuclear enrichment. As a signaling protein Pyk2 is involved in multiple pathways resulting in sometimes opposing functions depending on experimental models. Thus Pyk2 has a dual role on neurites and dendritic spines. With Src family kinases Pyk2 participates in postsynaptic regulations including of NMDA receptors and is necessary for specific types of synaptic plasticity and spatial memory tasks. The diverse functions of Pyk2 are also illustrated by its role in pathology. Pyk2 is activated following epileptic seizures or ischemia-reperfusion and may contribute to the consequences of these insults whereas Pyk2 deficit may contribute to the hippocampal phenotype of Huntington’s disease. Pyk2 gene, PTK2B, is associated with the risk for late-onset Alzheimer’s disease. Studies of underlying mechanisms indicate a complex contribution with involvement in amyloid toxicity and tauopathy, combined with possible functional deficits in neurons and contribution in microglia. A role of Pyk2 has also been proposed in stress-induced depression and cocaine addiction. Pyk2 is also important for the mobility of astrocytes and glioblastoma cells. The implication of Pyk2 in various pathological conditions supports its potential interest for therapeutic interventions. This is possible through molecules inhibiting its activity or increasing it through inhibition of STEP or other means, depending on a precise evaluation of the balance between positive and negative consequences of Pyk2 actions.
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Affiliation(s)
- Benoit de Pins
- Institut du Fer à Moulin, Paris, France.,Inserm UMR-S 1270, Paris, France.,Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
| | - Tiago Mendes
- Institut du Fer à Moulin, Paris, France.,Inserm UMR-S 1270, Paris, France.,Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
| | - Albert Giralt
- Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.,Production and Validation Center of Advanced Therapies (Creatio), Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
| | - Jean-Antoine Girault
- Institut du Fer à Moulin, Paris, France.,Inserm UMR-S 1270, Paris, France.,Faculté des Sciences et Ingénierie, Sorbonne Université, Paris, France
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4
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Motz CT, Kabat V, Saxena T, Bellamkonda RV, Zhu C. Neuromechanobiology: An Expanding Field Driven by the Force of Greater Focus. Adv Healthc Mater 2021; 10:e2100102. [PMID: 34342167 PMCID: PMC8497434 DOI: 10.1002/adhm.202100102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 07/06/2021] [Indexed: 12/14/2022]
Abstract
The brain processes information by transmitting signals through highly connected and dynamic networks of neurons. Neurons use specific cellular structures, including axons, dendrites and synapses, and specific molecules, including cell adhesion molecules, ion channels and chemical receptors to form, maintain and communicate among cells in the networks. These cellular and molecular processes take place in environments rich of mechanical cues, thus offering ample opportunities for mechanical regulation of neural development and function. Recent studies have suggested the importance of mechanical cues and their potential regulatory roles in the development and maintenance of these neuronal structures. Also suggested are the importance of mechanical cues and their potential regulatory roles in the interaction and function of molecules mediating the interneuronal communications. In this review, the current understanding is integrated and promising future directions of neuromechanobiology are suggested at the cellular and molecular levels. Several neuronal processes where mechanics likely plays a role are examined and how forces affect ligand binding, conformational change, and signal induction of molecules key to these neuronal processes are indicated, especially at the synapse. The disease relevance of neuromechanobiology as well as therapies and engineering solutions to neurological disorders stemmed from this emergent field of study are also discussed.
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Affiliation(s)
- Cara T Motz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
| | - Victoria Kabat
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
| | - Tarun Saxena
- Department of Biomedical Engineering, Duke University, Durham, NC, 27709, USA
| | - Ravi V Bellamkonda
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, 27708, USA
| | - Cheng Zhu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
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5
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Chan JW, Chan NCY, Sadun AA. Glaucoma as Neurodegeneration in the Brain. Eye Brain 2021; 13:21-28. [PMID: 33500674 PMCID: PMC7822087 DOI: 10.2147/eb.s293765] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/07/2021] [Indexed: 12/31/2022] Open
Abstract
Glaucoma, a group of diseases characterized by progressive optic nerve degeneration that results in irreversible blindness, can be considered a neurodegenerative disorder of both the eye and the brain. Increasing evidence from human and animal studies have shown that glaucoma shares some common neurodegenerative pathways with Alzheimer’s disease (AD) and other tauopathies, such as chronic traumatic encephalopathy (CTE) and frontotemporal dementia. This hypothesis is based on the focal adhesion pathway hypothesis and the spreading hypothesis of tau. Not only has the Apolipoprotein E (APOE) gene been shown to be associated with AD, but also with primary open angle glaucoma (POAG). This review will highlight the relevant literature in the past 20 years from PubMed that show the pathogenic overlap between POAG and AD. Neurodegenerative pathways that contribute to transsynaptic neurodegeneration in AD and other tauopathies might also be similar to those in glaucomatous neurodegeneration.
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Affiliation(s)
- Jane W Chan
- Department of Ophthalmology, Doheny Eye Institute, Pasadena, CA, USA
| | - Noel C Y Chan
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, N.T., Hong Kong, People's Republic of China
| | - Alfredo A Sadun
- Department of Ophthalmology, Doheny Eye Institute, Pasadena, CA, USA.,Department of Ophthalmology, University of California, Los Angeles, CA, USA
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6
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Huang YA, Hsu CH, Chiu HC, Hsi PY, Ho CT, Lo WL, Hwang E. Actin waves transport RanGTP to the neurite tip to regulate non-centrosomal microtubules in neurons. J Cell Sci 2020; 133:jcs241992. [PMID: 32253322 DOI: 10.1242/jcs.241992] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/17/2020] [Indexed: 12/18/2022] Open
Abstract
Microtubules (MTs) are the most abundant cytoskeleton in neurons, and control multiple facets of their development. While the MT-organizing center (MTOC) in mitotic cells is typically located at the centrosome, the MTOC in neurons switches to non-centrosomal sites. A handful of cellular components have been shown to promote non-centrosomal MT (ncMT) formation in neurons, yet the regulation mechanism remains unknown. Here, we demonstrate that the small GTPase Ran is a key regulator of ncMTs in neurons. Using an optogenetic tool that enables light-induced local production of RanGTP, we demonstrate that RanGTP promotes ncMT plus-end growth along the neurite. Additionally, we discovered that actin waves drive the anterograde transport of RanGTP. Pharmacological disruption of actin waves abolishes the enrichment of RanGTP and reduces growing ncMT plus-ends at the neurite tip. These observations identify a novel regulation mechanism for ncMTs and pinpoint an indirect connection between the actin and MT cytoskeletons in neurons.
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Affiliation(s)
- Yung-An Huang
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan 30068
| | - Chih-Hsuan Hsu
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu, Taiwan 30068
| | - Ho-Chieh Chiu
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu, Taiwan 30068
| | - Pei-Yu Hsi
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu, Taiwan 30068
| | - Chris T Ho
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu, Taiwan 30068
| | - Wei-Lun Lo
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan 30068
| | - Eric Hwang
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan 30068
- Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu, Taiwan 30068
- Institute of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, Taiwan 30068
- Center for Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Chiao Tung University, Hsinchu, Taiwan 30068
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7
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Bhute S, Sarmah D, Datta A, Rane P, Shard A, Goswami A, Borah A, Kalia K, Dave KR, Bhattacharya P. Molecular Pathogenesis and Interventional Strategies for Alzheimer's Disease: Promises and Pitfalls. ACS Pharmacol Transl Sci 2020; 3:472-488. [PMID: 32566913 DOI: 10.1021/acsptsci.9b00104] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) is a debilitating disorder characterized by age-related dementia, which has no effective treatment to date. β-Amyloid depositions and hyperphosphorylated tau proteins are the main pathological hallmarks, along with oxidative stress, N-methyl-d-aspartate (NMDA) receptor-mediated excitotoxicity, and low levels of acetylcholine. Current pharmacotherapy for AD only provides symptomatic relief and limited improvement in cognitive functions. Many molecules have been explored that show promising outcomes in AD therapy and can regulate cellular survival through different pathways. To have a vivid approach to strategize the treatment regimen, AD physiopathology should be better explained considering diverse etiological factors in conjunction with biochemical disturbances. This Review attempts to discuss different disease modification approaches and address the novel therapeutic targets of AD that might pave the way for new drug discovery using the well-defined targets for therapy of the disease.
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Affiliation(s)
- Shashikala Bhute
- Department of Pharmacology and Toxicology,National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
| | - Deepaneeta Sarmah
- Department of Pharmacology and Toxicology,National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
| | - Aishika Datta
- Department of Pharmacology and Toxicology,National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
| | - Pallavi Rane
- Department of Pharmacology and Toxicology,National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
| | - Amit Shard
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
| | - Avirag Goswami
- Department of Neurology, Albert Einstein Medical Center, Philadelphia, Pennsylvania 19141, United States
| | - Anupom Borah
- Department of Life Science and Bioinformatics, Assam University, Silchar, Assam-788011, India
| | - Kiran Kalia
- Department of Pharmacology and Toxicology,National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
| | - Kunjan R Dave
- Department of Neurology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Pallab Bhattacharya
- Department of Pharmacology and Toxicology,National Institute of Pharmaceutical Education and Research (NIPER), Ahmedabad, Gandhinagar-382355, Gujarat, India
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Wu G, Li J, Qin C. Reduced RANBP9 expression is associated with poor prognosis in colorectal cancer patients. Transl Cancer Res 2019; 8:2704-2712. [PMID: 35117028 PMCID: PMC8797687 DOI: 10.21037/tcr.2019.10.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 10/10/2019] [Indexed: 11/09/2022]
Abstract
Background Colorectal cancer (CRC) is the third most common malignancy worldwide. RANBP9 is a RAN-binding protein that has been reported to be a reliable predictor for prognosis in some human cancers. The mechanism of RANBP9 involvement in CRC carcinogenesis is unknown. This study measured RANBP9 expression levels in CRC to determine its association with clinicopathological parameters. Methods This study included 228 CRC patients who underwent radical resection. RANBP9 expression was determined using immunohistochemistry. Based on follow-up data, the correlation of RANBP9 expression levels with clinicopathological parameters, including disease free survival (DFS) and overall survival (OS) was evaluated. Results Reduced RANBP9 expression was correlated with tumor location (P=0.014), vascular invasion (P=0.057) and normal serum carcinoembryonic antigen levels (P=0.001). Patients with reduced RANBP9 expression had a 5-year DFS rate of 63.0% compared to 78.9% for patients with high expression levels of RANBP9 (P=0.015). Subgroup analysis demonstrated that reduced RANBP9 expression was significantly correlated with a worse DFS rate (P=0.037) for patients with left-sided colon cancer. RANBP9 was found to be an independent predictive factor for estimating DFS rate (P=0.029, hazard ratio: 0.580, 95% confidence interval: 0.356–0.946) and OS. Conclusions RANBP9 expression levels is a potential prognostic factor for estimating CRC survival rates in patients after surgery.
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Affiliation(s)
- Guangbin Wu
- Department of General surgery, Jinshan Hospital, Fudan University, Shanghai 201508, China
| | - Ji Li
- Department of General surgery, Jinshan Hospital, Fudan University, Shanghai 201508, China
| | - Chunzhi Qin
- Department of General surgery, Jinshan Hospital, Fudan University, Shanghai 201508, China
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9
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The CTLH Complex in Cancer Cell Plasticity. JOURNAL OF ONCOLOGY 2019; 2019:4216750. [PMID: 31885576 PMCID: PMC6907057 DOI: 10.1155/2019/4216750] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/24/2019] [Accepted: 10/25/2019] [Indexed: 12/12/2022]
Abstract
Cancer cell plasticity is the ability of cancer cells to intermittently morph into different fittest phenotypic states. Due to the intrinsic capacity to change their composition and interactions, protein macromolecular complexes are the ideal instruments for transient transformation. This review focuses on a poorly studied mammalian macromolecular complex called the CTLH (carboxy-terminal to LisH) complex. Currently, this macrostructure includes 11 known members (ARMC8, GID4, GID8, MAEA, MKLN1, RMND5A, RMND5B, RANBP9, RANBP10, WDR26, and YPEL5) and it has been shown to have E3-ligase enzymatic activity. CTLH proteins have been linked to all fundamental biological processes including proliferation, survival, programmed cell death, cell adhesion, and migration. At molecular level, the complex seems to interact and intertwine with key signaling pathways such as the PI3-kinase, WNT, TGFβ, and NFκB, which are key to cancer cell plasticity. As a whole, the CTLH complex is overexpressed in the most prevalent types of cancer and may hold the key to unlock many of the biological secrets that allow cancer cells to thrive in harsh conditions and resist antineoplastic therapy.
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10
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Liu T, Woo JAA, Yan Y, LePochat P, Bukhari MZ, Kang DE. Dual role of cofilin in APP trafficking and amyloid-β clearance. FASEB J 2019; 33:14234-14247. [PMID: 31646885 DOI: 10.1096/fj.201901268r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The accumulation of amyloid-β (Aβ) plays a pivotal early event in the pathogenesis of Alzheimer's disease (AD). In the brain, neurons produce Aβ by the proteolytic processing of amyloid precursor protein (APP) through the endocytic pathway, whereas microglia mediate Aβ clearance also via endocytic mechanisms. Previous studies have shown the critical importance of cofilin, a filamentous actin-severing protein, in actin dynamics and pathogen-triggered endocytic processes. Moreover, the binding of Aβ42 oligomers to β1-integrin triggers the cofilin activation, and in turn, cofilin promotes the internalization of surface β1-integrin. However, a role for cofilin in APP processing and Aβ metabolism has not been investigated. In this study, we found that knockdown of cofilin in Chinese hamster ovary 7WD10 cells and primary neurons significantly reduces Aβ production by increasing surface APP (sAPP) levels. Expression of active (S3A) but not inactive (S3E) cofilin reduces sAPP levels by enhancing APP endocytosis. Accordingly, Aβ deposition in APP and presenilin 1 (PS1) transgenic mice is significantly reduced by genetic reduction of cofilin (APP/PS1;cofilin+/-). However, the reduction of Aβ load in APP/PS1;cofilin+/- mice is paradoxically associated with significantly increased ionized calcium-binding adaptor molecule 1-positive microglial activation surrounding Aβ deposits. Primary microglia isolated from cofilin+/- mice demonstrate significantly enhanced state of activation and greater ability to uptake and clear Aβ42, which is reversed with the active (S3A) but not inactive (S3E) form of cofilin. These results taken together indicate a significant role for cofilin in Aβ accumulation via dual and opposing endocytic mechanisms of promoting Aβ production in neurons and inhibiting Aβ clearance in microglia.-Liu, T., Woo, J.-A. A., Yan, Y., LePochat, P., Bukhari, M. Z., Kang, D. E. Dual role of cofilin in APP trafficking and amyloid-β clearance.
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Affiliation(s)
- Tian Liu
- Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,Department of Molecular of Medicine, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA
| | - Jung-A A Woo
- Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA
| | - Yan Yan
- Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,Department of Molecular of Medicine, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA
| | - Patrick LePochat
- Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,Department of Molecular of Medicine, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA
| | - Mohammed Zaheen Bukhari
- Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,Department of Molecular of Medicine, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA
| | - David E Kang
- Byrd Alzheimer's Institute, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,Department of Molecular of Medicine, Morsani College of Medicine, University of South Florida (USF) Health, Tampa, Florida, USA.,James A. Haley Veterans Administration Hospital, Tampa, Florida, USA
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11
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Dourlen P, Kilinc D, Malmanche N, Chapuis J, Lambert JC. The new genetic landscape of Alzheimer's disease: from amyloid cascade to genetically driven synaptic failure hypothesis? Acta Neuropathol 2019; 138:221-236. [PMID: 30982098 PMCID: PMC6660578 DOI: 10.1007/s00401-019-02004-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/30/2019] [Accepted: 04/02/2019] [Indexed: 12/18/2022]
Abstract
A strong genetic predisposition (60–80% of attributable risk) is present in Alzheimer’s disease (AD). In view of this major genetic component, identification of the genetic risk factors has been a major objective in the AD field with the ultimate aim to better understand the pathological processes. In this review, we present how the genetic risk factors are involved in APP metabolism, β-amyloid peptide production, degradation, aggregation and toxicity, innate immunity, and Tau toxicity. In addition, on the basis of the new genetic landscape, resulting from the recent high-throughput genomic approaches and emerging neurobiological information, we propose an over-arching model in which the focal adhesion pathway and the related cell signalling are key elements in AD pathogenesis. The core of the focal adhesion pathway links the physiological functions of amyloid precursor protein and Tau with the pathophysiological processes they are involved in. This model includes several entry points, fitting with the different origins for the disease, and supports the notion that dysregulation of synaptic plasticity is a central node in AD. Notably, our interpretation of the latest data from genome wide association studies complements other hypotheses already developed in the AD field, i.e., amyloid cascade, cellular phase or propagation hypotheses. Genetically driven synaptic failure hypothesis will need to be further tested experimentally within the general AD framework.
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Affiliation(s)
- Pierre Dourlen
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Devrim Kilinc
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Nicolas Malmanche
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Julien Chapuis
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France
| | - Jean-Charles Lambert
- Unité INSERM 1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases, Institut Pasteur de Lille, University of Lille, U1167-Excellence Laboratory LabEx DISTALZ, BP 245, 1, rue du professeur Calmette, 59019, Lille Cedex, France.
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12
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Qin C, Zhang Q, Wu G. RANBP9 suppresses tumor proliferation in colorectal cancer. Oncol Lett 2019; 17:4409-4416. [PMID: 30988811 PMCID: PMC6447939 DOI: 10.3892/ol.2019.10134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 02/11/2019] [Indexed: 12/16/2022] Open
Abstract
RAN binding protein 9 (RANBP9) is widely expressed in mammalian tissues, including osteosarcoma, lung, gastric and breast cancer tissues. However, currently, not much is known about the role of RANBP9 in colorectal cancer (CRC). In the present study, RANBP9 expression in CRC tissues and cell lines was measured by immunohistochemistry and western blotting, respectively. Subsequently, RANBP9-short hairpin RNA (shRNA) and RANBP9 plasmids were constructed and transfected into HCT116 and HT29 cells. The effects of RANBP9 knockdown were assessed by Cell Counting kit-8 and colony formation assays, and its effects on tumorigenicity in a nude mouse animal model were investigated. The effect of RANBP9-shRNA on cell cycle progression was analyzed by flow cytometry, while cell cycle-associated protein expression levels were examined by western blotting. Compared with in paired normal mucosa, RANBP9 was overexpressed in CRC tissues. Inhibition of RANBP9 in HCT116 and HT29 cells significantly promoted cell growth, colony formation and S phase transition, and increased tumorigenesis in vivo. Accordingly, RANBP9 overexpression inhibited cell growth and colony formation. Knockdown of RANBP9 was associated with upregulated cyclin A2 in the two cell lines. In conclusion, RANBP9 served an inhibitory role in CRC in vitro and in vivo. Therefore, RANBP9 may be considered a potential target for treatment of CRC.
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Affiliation(s)
- Chunzhi Qin
- Department of General Surgery, Jinshan Hospital, Fudan University, Shanghai 201508, P.R. China
| | - Qin Zhang
- Department of General Surgery, Jinshan Hospital, Fudan University, Shanghai 201508, P.R. China
| | - Guangbin Wu
- Department of General Surgery, Jinshan Hospital, Fudan University, Shanghai 201508, P.R. China
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13
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Bres EE, Faissner A. Low Density Receptor-Related Protein 1 Interactions With the Extracellular Matrix: More Than Meets the Eye. Front Cell Dev Biol 2019; 7:31. [PMID: 30931303 PMCID: PMC6428713 DOI: 10.3389/fcell.2019.00031] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 02/25/2019] [Indexed: 12/12/2022] Open
Abstract
The extracellular matrix (ECM) is a biological substrate composed of collagens, proteoglycans and glycoproteins that ensures proper cell migration and adhesion and keeps the cell architecture intact. The regulation of the ECM composition is a vital process strictly controlled by, among others, proteases, growth factors and adhesion receptors. As it appears, ECM remodeling is also essential for proper neuronal and glial development and the establishment of adequate synaptic signaling. Hence, disturbances in ECM functioning are often present in neurodegenerative diseases like Alzheimer’s disease. Moreover, mutations in ECM molecules are found in some forms of epilepsy and malfunctioning of ECM-related genes and pathways can be seen in, for example, cancer or ischemic injury. Low density lipoprotein receptor-related protein 1 (Lrp1) is a member of the low density lipoprotein receptor family. Lrp1 is involved not only in ligand uptake, receptor mediated endocytosis and lipoprotein transport—functions shared by low density lipoprotein receptor family members—but also regulates cell surface protease activity, controls cellular entry and binding of toxins and viruses, protects against atherosclerosis and acts on many cell signaling pathways. Given the plethora of functions, it is not surprising that Lrp1 also impacts the ECM and is involved in its remodeling. This review focuses on the role of Lrp1 and some of its major ligands on ECM function. Specifically, interactions with two Lrp1 ligands, integrins and tissue plasminogen activator are described in more detail.
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Affiliation(s)
- Ewa E Bres
- Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum, Bochum, Germany
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, Ruhr University Bochum, Bochum, Germany
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14
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Salemi LM, Maitland MER, McTavish CJ, Schild-Poulter C. Cell signalling pathway regulation by RanBPM: molecular insights and disease implications. Open Biol 2018; 7:rsob.170081. [PMID: 28659384 PMCID: PMC5493780 DOI: 10.1098/rsob.170081] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 06/01/2017] [Indexed: 12/25/2022] Open
Abstract
RanBPM (Ran-binding protein M, also called RanBP9) is an evolutionarily conserved, ubiquitous protein which localizes to both nucleus and cytoplasm. RanBPM has been implicated in the regulation of a number of signalling pathways to regulate several cellular processes such as apoptosis, cell adhesion, migration as well as transcription, and plays a critical role during development. In addition, RanBPM has been shown to regulate pathways implicated in cancer and Alzheimer's disease, implying that RanBPM has important functions in both normal and pathological development. While its functions in these processes are still poorly understood, RanBPM has been identified as a component of a large complex, termed the CTLH (C-terminal to LisH) complex. The yeast homologue of this complex functions as an E3 ubiquitin ligase that targets enzymes of the gluconeogenesis pathway. While the CTLH complex E3 ubiquitin ligase activity and substrates still remain to be characterized, the high level of conservation between the complexes in yeast and mammals infers that the CTLH complex could also serve to promote the degradation of specific substrates through ubiquitination, therefore suggesting the possibility that RanBPM's various functions may be mediated through the activity of the CTLH complex.
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Affiliation(s)
- Louisa M Salemi
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
| | - Matthew E R Maitland
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
| | - Christina J McTavish
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
| | - Caroline Schild-Poulter
- Robarts Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1151 Richmond Street North, London, Ontario, Canada N6A 5B7
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15
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Madry C, Arancibia-Cárcamo IL, Kyrargyri V, Chan VTT, Hamilton NB, Attwell D. Effects of the ecto-ATPase apyrase on microglial ramification and surveillance reflect cell depolarization, not ATP depletion. Proc Natl Acad Sci U S A 2018; 115:E1608-E1617. [PMID: 29382767 PMCID: PMC5816168 DOI: 10.1073/pnas.1715354115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Microglia, the brain's innate immune cells, have highly motile processes which constantly survey the brain to detect infection, remove dying cells, and prune synapses during brain development. ATP released by tissue damage is known to attract microglial processes, but it is controversial whether an ambient level of ATP is needed to promote constant microglial surveillance in the normal brain. Applying the ATPase apyrase, an enzyme which hydrolyzes ATP and ADP, reduces microglial process ramification and surveillance, suggesting that ambient ATP/ADP maintains microglial surveillance. However, attempting to raise the level of ATP/ADP by blocking the endogenous ecto-ATPase (termed NTPDase1/CD39), which also hydrolyzes ATP/ADP, does not affect the cells' ramification or surveillance, nor their membrane currents, which respond to even small rises of extracellular [ATP] or [ADP] with the activation of K+ channels. This indicates a lack of detectable ambient ATP/ADP and ecto-ATPase activity, contradicting the results with apyrase. We resolve this contradiction by demonstrating that contamination of commercially available apyrase by a high K+ concentration reduces ramification and surveillance by depolarizing microglia. Exposure to the same K+ concentration (without apyrase added) reduced ramification and surveillance as with apyrase. Dialysis of apyrase to remove K+ retained its ATP-hydrolyzing activity but abolished the microglial depolarization and decrease of ramification produced by the undialyzed enzyme. Thus, applying apyrase affects microglia by an action independent of ATP, and no ambient purinergic signaling is required to maintain microglial ramification and surveillance. These results also have implications for hundreds of prior studies that employed apyrase to hydrolyze ATP/ADP.
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Affiliation(s)
- Christian Madry
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
- Institute of Neurophysiology, Charité Universitätsmedizin, 10117 Berlin, Germany
| | - I Lorena Arancibia-Cárcamo
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Vasiliki Kyrargyri
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Victor T T Chan
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Nicola B Hamilton
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
- Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom;
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16
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Woo JA, Liu T, Zhao X, Trotter C, Yrigoin K, Cazzaro S, Narvaez ED, Khan H, Witas R, Bukhari A, Makati K, Wang X, Dickey C, Kang DE. Enhanced tau pathology via RanBP9 and Hsp90/Hsc70 chaperone complexes. Hum Mol Genet 2017; 26:3973-3988. [PMID: 29016855 PMCID: PMC6075219 DOI: 10.1093/hmg/ddx284] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/04/2017] [Accepted: 07/14/2017] [Indexed: 12/26/2022] Open
Abstract
Accumulation of amyloid β (Aβ) and tau represent the two major pathological hallmarks of Alzheimer's disease (AD). Despite the critical importance of Aβ accumulation as an early event in AD pathogenesis, multiple lines of evidence indicate that tau is required to mediate Aβ-induced neurotoxic signals in neurons. We have previously shown that the scaffolding protein Ran-binding protein 9 (RanBP9), which is highly elevated in brains of AD and AD mouse models, both enhances Aβ production and mediates Aβ-induced neurotoxicity. However, it is unknown whether and how RanBP9 transmits Aβ-induced neurotoxic signals to tau. Here we show for the first time that overexpression or knockdown of RanBP9 directly enhances and reduces tau levels, respectively, in vitro and in vivo. Such changes in tau levels are associated with the ability of RanBP9 to physically interact with tau and heat shock protein 90/heat shock cognate 70 (Hsp90/Hsc70) complexes. Meanwhile, both RanBP9 and tau levels are simultaneously reduced by Hsp90 or Hsc70 inhibitors, whereas overexpression or knockdown of RanBP9 significantly diminishes the anti-tau potency of Hsp90/Hsc70 inhibitors as well as Hsc70 variants (WT & E175S). Further, RanBP9 increases the capacity for Hsp90 and Hsc70 complexes to bind ATP and enhances their ATPase activities in vitro. These observations in vitro and cell lines are recapitulated in primary neurons and in vivo, as genetic reduction in RanBP9 not only ameliorates tauopathy in Tau-P301S mice but also rescues the deficits in synaptic integrity and plasticity.
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Affiliation(s)
- Jung A Woo
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Medicine
| | - Tian Liu
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Medicine
| | - Xingyu Zhao
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Medicine
| | - Courtney Trotter
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Medicine
| | | | | | | | | | | | | | | | - Xinming Wang
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Pharmacology and Physiology, University of South Florida, Morsani College of Medicine, Tampa, FL 33613, USA
| | - Chad Dickey
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Medicine
- James A. Haley Veteran’s Administration Hospital, Research Division, Tampa, FL 33612, USA
| | - David E Kang
- USF Health Byrd Alzheimer’s Institute
- Department of Molecular Medicine
- James A. Haley Veteran’s Administration Hospital, Research Division, Tampa, FL 33612, USA
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17
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Das S, Suresh B, Kim HH, Ramakrishna S. RanBPM: a potential therapeutic target for modulating diverse physiological disorders. Drug Discov Today 2017; 22:1816-1824. [PMID: 28847759 DOI: 10.1016/j.drudis.2017.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 06/26/2017] [Accepted: 08/21/2017] [Indexed: 02/06/2023]
Abstract
The Ran-binding protein microtubule-organizing center (RanBPM) is a highly conserved nucleocytoplasmic protein involved in a variety of intracellular signaling pathways that control diverse cellular functions. RanBPM interacts with proteins that are linked to various diseases, including Alzheimer's disease (AD), schizophrenia (SCZ), and cancer. In this article, we define the characteristics of the scaffolding protein RanBPM and focus on its interaction partners in diverse physiological disorders, such as neurological diseases, fertility disorders, and cancer.
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Affiliation(s)
- Soumyadip Das
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, 04763, South Korea
| | - Bharathi Suresh
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, 03722, South Korea.
| | - Hyongbum Henry Kim
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, 03722, South Korea; Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul, 03722, South Korea; Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea; Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, 03722, South Korea.
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul, 04763, South Korea; College of Medicine, Hanyang University, Seoul, 04763, South Korea.
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18
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Millan MJ. Linking deregulation of non-coding RNA to the core pathophysiology of Alzheimer's disease: An integrative review. Prog Neurobiol 2017; 156:1-68. [PMID: 28322921 DOI: 10.1016/j.pneurobio.2017.03.004] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/09/2017] [Accepted: 03/09/2017] [Indexed: 02/06/2023]
Abstract
The human genome encodes a vast repertoire of protein non-coding RNAs (ncRNA), some specific to the brain. MicroRNAs, which interfere with the translation of target mRNAs, are of particular interest since their deregulation has been implicated in neurodegenerative disorders like Alzheimer's disease (AD). However, it remains challenging to link the complex body of observations on miRNAs and AD into a coherent framework. Using extensive graphical support, this article discusses how a diverse panoply of miRNAs convergently and divergently impact (and are impacted by) core pathophysiological processes underlying AD: neuroinflammation and oxidative stress; aberrant generation of β-amyloid-42 (Aβ42); anomalies in the production, cleavage and post-translational marking of Tau; impaired clearance of Aβ42 and Tau; perturbation of axonal organisation; disruption of synaptic plasticity; endoplasmic reticulum stress and the unfolded protein response; mitochondrial dysfunction; aberrant induction of cell cycle re-entry; and apoptotic loss of neurons. Intriguingly, some classes of miRNA provoke these cellular anomalies, whereas others act in a counter-regulatory, protective mode. Moreover, changes in levels of certain species of miRNA are a consequence of the above-mentioned anomalies. In addition to miRNAs, circular RNAs, piRNAs, long non-coding RNAs and other types of ncRNA are being increasingly implicated in AD. Overall, a complex mesh of deregulated and multi-tasking ncRNAs reciprocally interacts with core pathophysiological mechanisms underlying AD. Alterations in ncRNAs can be detected in CSF and the circulation as well as the brain and are showing promise as biomarkers, with the ultimate goal clinical exploitation as targets for novel modes of symptomatic and course-altering therapy.
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Affiliation(s)
- Mark J Millan
- Centre for Therapeutic Innovation in Neuropsychiatry, institut de recherche Servier, 125 chemin de ronde, 78290 Croissy sur Seine, France.
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19
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Ran-dependent TPX2 activation promotes acentrosomal microtubule nucleation in neurons. Sci Rep 2017; 7:42297. [PMID: 28205572 PMCID: PMC5304320 DOI: 10.1038/srep42297] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/05/2017] [Indexed: 01/07/2023] Open
Abstract
The microtubule (MT) cytoskeleton is essential for the formation of morphologically appropriate neurons. The existence of the acentrosomal MT organizing center in neurons has been proposed but its identity remained elusive. Here we provide evidence showing that TPX2 is an important component of this acentrosomal MT organizing center. First, neurite elongation is compromised in TPX2-depleted neurons. In addition, TPX2 localizes to the centrosome and along the neurite shaft bound to MTs. Depleting TPX2 decreases MT formation frequency specifically at the tip and the base of the neurite, and these correlate precisely with the regions where active GTP-bound Ran proteins are enriched. Furthermore, overexpressing the downstream effector of Ran, importin, compromises MT formation and neuronal morphogenesis. Finally, applying a Ran-importin signaling interfering compound phenocopies the effect of TPX2 depletion on MT dynamics. Together, these data suggest a model in which Ran-dependent TPX2 activation promotes acentrosomal MT nucleation in neurons.
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20
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Petrov AM, Kasimov MR, Zefirov AL. Cholesterol in the Pathogenesis of Alzheimer's, Parkinson's Diseases and Autism: Link to Synaptic Dysfunction. Acta Naturae 2017; 9:26-37. [PMID: 28461971 PMCID: PMC5406657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Indexed: 11/30/2022] Open
Abstract
In our previous review, we described brain cholesterol metabolism in control conditions and in the case of some rare neurological pathologies linked to defects in the genes which are directly involved in the synthesis and/or traffic of cholesterol. Here, we have analyzed disruptions in cholesterol homeostasis in widespread neurodegenerative diseases (Alzheimer's and Parkinson's diseases) and autism spectrum disorders. We particularly focused on the synaptic dysfunctions that could arise from changes in both membrane cholesterol availability and oxysterol production. Notably, alterations in the brain cholesterol metabolism and neurotransmission occur in the early stages of these pathologies and the polymorphism of the genes associated with cholesterol homeostasis and synaptic communication affects the risk of onset and severity of these diseases. In addition, pharmacological and genetic manipulations of brain cholesterol homeostasis in animal models frequently have marked effects on the progression of neurodegenerative diseases. Thus, the development of Alzheimer's, Parkinson's and autism spectrum disorders may be partially associated with an imbalance of cholesterol homeostasis that leads to changes in the membrane cholesterol and oxysterol levels that, in turn, modulates key steps in the synaptic transmission.
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Affiliation(s)
- A. M. Petrov
- Kazan State Medical University, Normal Physiology department, Butlerova str. 49, Kazan, 420012, Russia
| | - M. R. Kasimov
- Kazan State Medical University, Normal Physiology department, Butlerova str. 49, Kazan, 420012, Russia
| | - A. L. Zefirov
- Kazan State Medical University, Normal Physiology department, Butlerova str. 49, Kazan, 420012, Russia
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21
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APP Receptor? To Be or Not To Be. Trends Pharmacol Sci 2016; 37:390-411. [PMID: 26837733 DOI: 10.1016/j.tips.2016.01.005] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/07/2016] [Accepted: 01/11/2016] [Indexed: 11/22/2022]
Abstract
Amyloid precursor protein (APP) and its metabolites play a key role in Alzheimer's disease pathogenesis. The idea that APP may function as a receptor has gained momentum based on its structural similarities to type I transmembrane receptors and the identification of putative APP ligands. We review the recent experimental evidence in support of this notion and discuss how this concept is viewed in the field. Specifically, we focus on the structural and functional characteristics of APP as a cell surface receptor, and on its interaction with adaptors and signaling proteins. We also address the importance of APP function as a receptor in Alzheimer's disease etiology and discuss how this function might be potentially important for the development of novel therapeutic approaches.
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22
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Rabiej VK, Pflanzner T, Wagner T, Goetze K, Storck SE, Eble JA, Weggen S, Mueller-Klieser W, Pietrzik CU. Low density lipoprotein receptor-related protein 1 mediated endocytosis of β1-integrin influences cell adhesion and cell migration. Exp Cell Res 2015; 340:102-15. [PMID: 26610862 DOI: 10.1016/j.yexcr.2015.11.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 11/29/2022]
Abstract
The low density lipoprotein receptor-related protein 1 (LRP1) has been shown to interact with β1-integrin and regulate its surface expression. LRP1 knock-out cells exhibit altered cytoskeleton organization and decreased cell migration. Here we demonstrate coupled endocytosis of LRP1 and β1-integrin and the involvement of the intracellular NPxY2 motif of LRP1 in this process. Mouse embryonic fibroblasts harboring a knock in replacement of the NPxY2 motif of LRP1 by a multiple alanine cassette (AAxA) showed elevated surface expression of β1-integrin and decreased β1-integrin internalization rates. As a consequence, cell spreading was altered and adhesion rates were increased in our cell model. Cells formed more focal adhesion complexes, whereby in vitro cell migration rates were decreased. Similar results could be observed in a corresponding mouse model, the C57Bl6 LRP1 NPxYxxL knock in mice, therefore, the biochemistry of cellular adhesion was altered in primary cortical neurons. In vivo cell migration experiments demonstrated a disturbance of neuroblast cell migration along the rostral migratory stream. In summary, our results indicate that LRP1 interacts with β1-integrin mediating integrin internalization and thus correlates with downstream signaling of β1-integrin such as focal adhesion dynamics. Consequently, the disturbance of this interaction resulted in a dysfunction in in vivo and in vitro cell adhesion and cell migration.
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Affiliation(s)
- Verena K Rabiej
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany
| | - Thorsten Pflanzner
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany
| | - Timo Wagner
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany
| | - Kristina Goetze
- Institute of Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany
| | - Steffen E Storck
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany
| | - Johannes A Eble
- Institute of Physiological Chemistry and Pathobiochemistry, Westfälische Wilhelms-University Muenster, Waldeyerstraße 15, 48149 Muenster, Germany
| | - Sascha Weggen
- Department of Neuropathology, Heinrich-Heine-University, Moorenstraße 5, 40225 Duesseldorf, Germany
| | - Wolfgang Mueller-Klieser
- Institute of Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany
| | - Claus U Pietrzik
- Institute of Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University, Duesbergweg 6, 55099 Mainz, Germany.
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23
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Young K, Tweedie E, Conley B, Ames J, FitzSimons M, Brooks P, Liaw L, Vary CPH. BMP9 Crosstalk with the Hippo Pathway Regulates Endothelial Cell Matricellular and Chemokine Responses. PLoS One 2015; 10:e0122892. [PMID: 25909848 PMCID: PMC4409298 DOI: 10.1371/journal.pone.0122892] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 02/24/2015] [Indexed: 12/26/2022] Open
Abstract
Endoglin is a type III TGFβ auxiliary receptor that is upregulated in endothelial cells during angiogenesis and, when mutated in humans, results in the vascular disease hereditary hemorrhagic telangiectasia (HHT). Though endoglin has been implicated in cell adhesion, the underlying molecular mechanisms are still poorly understood. Here we show endoglin expression in endothelial cells regulates subcellular localization of zyxin in focal adhesions in response to BMP9. RNA knockdown of endoglin resulted in mislocalization of zyxin and altered formation of focal adhesions. The mechanotransduction role of focal adhesions and their ability to transmit regulatory signals through binding of the extracellular matrix are altered by endoglin deficiency. BMP/TGFβ transcription factors, SMADs, and zyxin have recently been implicated in a newly emerging signaling cascade, the Hippo pathway. The Hippo transcription coactivator, YAP1 (yes-associated protein 1), has been suggested to play a crucial role in mechanotransduction and cell-cell contact. Identification of BMP9-dependent nuclear localization of YAP1 in response to endoglin expression suggests a mechanism of crosstalk between the two pathways. Suppression of endoglin and YAP1 alters BMP9-dependent expression of YAP1 target genes CCN1 (cysteine-rich 61, CYR61) and CCN2 (connective tissue growth factor, CTGF) as well as the chemokine CCL2 (monocyte chemotactic protein 1, MCP-1). These results suggest a coordinate effect of endoglin deficiency on cell matrix remodeling and local inflammatory responses. Identification of a direct link between the Hippo pathway and endoglin may reveal novel mechanisms in the etiology of HHT.
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Affiliation(s)
- Kira Young
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, Maine 04469, United States of America
| | - Eric Tweedie
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
| | - Barbara Conley
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
| | - Jacquelyn Ames
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, Maine 04469, United States of America
| | - MaryLynn FitzSimons
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, Maine 04469, United States of America
| | - Peter Brooks
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, Maine 04469, United States of America
| | - Lucy Liaw
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, Maine 04469, United States of America
| | - Calvin P. H. Vary
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074, United States of America
- Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, Maine 04469, United States of America
- * E-mail:
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Woo JA, Boggess T, Uhlar C, Wang X, Khan H, Cappos G, Joly-Amado A, De Narvaez E, Majid S, Minamide LS, Bamburg JR, Morgan D, Weeber E, Kang DE. RanBP9 at the intersection between cofilin and Aβ pathologies: rescue of neurodegenerative changes by RanBP9 reduction. Cell Death Dis 2015; 6:1676. [PMID: 25741591 PMCID: PMC4385917 DOI: 10.1038/cddis.2015.37] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 01/05/2015] [Accepted: 01/19/2015] [Indexed: 12/21/2022]
Abstract
Molecular pathways underlying the neurotoxicity and production of amyloid β protein (Aβ) represent potentially promising therapeutic targets for Alzheimer's disease (AD). We recently found that overexpression of the scaffolding protein RanBP9 increases Aβ production in cell lines and in transgenic mice while promoting cofilin activation and mitochondrial dysfunction. Translocation of cofilin to mitochondria and induction of cofilin–actin pathology require the activation/dephosphorylation of cofilin by Slingshot homolog 1 (SSH1) and cysteine oxidation of cofilin. In this study, we found that endogenous RanBP9 positively regulates SSH1 levels and mediates Aβ-induced translocation of cofilin to mitochondria and induction of cofilin–actin pathology in cultured cells, primary neurons, and in vivo. Endogenous level of RanBP9 was also required for Aβ-induced collapse of growth cones in immature neurons (days in vitro 9 (DIV9)) and depletion of synaptic proteins in mature neurons (DIV21). In vivo, amyloid precursor protein (APP)/presenilin-1 (PS1) mice exhibited 3.5-fold increased RanBP9 levels, and RanBP9 reduction protected against cofilin–actin pathology, synaptic damage, gliosis, and Aβ accumulation associated with APP/PS1 mice. Brains slices derived from APP/PS1 mice showed significantly impaired long-term potentiation (LTP), and RanBP9 reduction significantly enhanced paired pulse facilitation and LTP, as well as partially rescued contextual memory deficits associated with APP/PS1 mice. Therefore, these results underscore the critical importance of endogenous RanBP9 not only in Aβ accumulation but also in mediating the neurotoxic actions of Aβ at the level of synaptic plasticity, mitochondria, and cofilin–actin pathology via control of the SSH1-cofilin pathway in vivo.
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Affiliation(s)
- J A Woo
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - T Boggess
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - C Uhlar
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - X Wang
- Department of Molecular Pharmacology and Physiology, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - H Khan
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - G Cappos
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - A Joly-Amado
- Department of Molecular Pharmacology and Physiology, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - E De Narvaez
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - S Majid
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - L S Minamide
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - J R Bamburg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - D Morgan
- Department of Molecular Pharmacology and Physiology, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - E Weeber
- Department of Molecular Pharmacology and Physiology, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
| | - D E Kang
- Department of Molecular Medicine, USF Health Byrd Alzheimer's Institute, Tampa, FL, USA
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Wang R, Wang H, Carrera I, Xu S, Lakshmana MK. COPS5 protein overexpression increases amyloid plaque burden, decreases spinophilin-immunoreactive puncta, and exacerbates learning and memory deficits in the mouse brain. J Biol Chem 2015; 290:9299-309. [PMID: 25713139 DOI: 10.1074/jbc.m114.595926] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Indexed: 01/05/2023] Open
Abstract
Brain accumulation of neurotoxic amyloid β (Aβ) peptide because of increased processing of amyloid precursor protein (APP), resulting in loss of synapses and neurodegeneration, is central to the pathogenesis of Alzheimer disease (AD). Therefore, the identification of molecules that regulate Aβ generation and those that cause synaptic damage is crucial for future therapeutic approaches for AD. We demonstrated previously that COPS5 regulates Aβ generation in neuronal cell lines in a RanBP9-dependent manner. Consistent with the data from cell lines, even by 6 months, COPS5 overexpression in APΔE9 mice (APΔE9/COPS5-Tg) significantly increased Aβ40 levels by 32% (p < 0.01) in the cortex and by 28% (p < 0.01) in the hippocampus, whereas the increases for Aβ42 were 37% (p < 0.05) and 34% (p < 0.05), respectively. By 12 months, the increase was even more robust. Aβ40 levels increased by 63% (p < 0.001) in the cortex and by 65% (p < 0.001) in the hippocampus. Similarly, Aβ42 levels were increased by 69% (p < 0.001) in the cortex and by 71% (p < 0.011) in the hippocampus. Increased Aβ levels were translated into an increased amyloid plaque burden both in the cortex (54%, p < 0.01) and hippocampus (64%, p < 0.01). Interestingly, COPS5 overexpression increased RanBP9 levels in the brain, which, in turn, led to increased amyloidogenic processing of APP, as reflected by increased levels of sAPPβ and decreased levels of sAPPα. Furthermore, COPS5 overexpression reduced spinophilin in both the cortex (19%, p < 0.05) and the hippocampus (20%, p < 0.05), leading to significant deficits in learning and memory skills. Therefore, like RanBP9, COPS5 also plays a pivotal role in amyloid pathology in vivo.
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Affiliation(s)
- Ruizhi Wang
- From the Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida 34987
| | - Hongjie Wang
- From the Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida 34987
| | - Ivan Carrera
- the Department of Neuroscience, Euroespes Biotechnology, Poligono de Bergondo, Nave F, 15165A, A Coruna, Spain, and
| | - Shaohua Xu
- the Florida Institute of Technology, Melbourne, Florida 32901
| | - Madepalli K Lakshmana
- From the Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida 34987,
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Salemi LM, Loureiro SO, Schild-Poulter C. Characterization of RanBPM molecular determinants that control its subcellular localization. PLoS One 2015; 10:e0117655. [PMID: 25659156 PMCID: PMC4319831 DOI: 10.1371/journal.pone.0117655] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 12/30/2014] [Indexed: 12/14/2022] Open
Abstract
RanBPM/RanBP9 is a ubiquitous, nucleocytoplasmic protein that is part of an evolutionary conserved E3 ubiquitin ligase complex whose function and targets in mammals are still unknown. RanBPM itself has been implicated in various cellular processes that involve both nuclear and cytoplasmic functions. However, to date, little is known about how RanBPM subcellular localization is regulated. We have conducted a systematic analysis of RanBPM regions that control its subcellular localization using RanBPM shRNA cells to examine ectopic RanBPM mutant subcellular localization without interference from the endogenously expressed protein. We show that several domains and motifs regulate RanBPM nuclear and cytoplasmic localization. In particular, RanBPM comprises two motifs that can confer nuclear localization, one proline/glutamine-rich motif in the extreme N-terminus which has a dominant effect on RanBPM localization, and a second motif in the C-terminus which minimally contributes to RanBPM nuclear targeting. We also identified a nuclear export signal (NES) which mutation prevented RanBPM accumulation in the cytoplasm. Likewise, deletion of the central RanBPM conserved domains (SPRY and LisH/CTLH) resulted in the relocalization of RanBPM to the nucleus, suggesting that RanBPM cytoplasmic localization is also conferred by protein-protein interactions that promote its cytoplasmic retention. Indeed we found that in the cytoplasm, RanBPM partially colocalizes with microtubules and associates with α-tubulin. Finally, in the nucleus, a significant fraction of RanBPM is associated with chromatin. Altogether, these analyses reveal that RanBPM subcellular localization results from the combined effects of several elements that either confer direct transport through the nucleocytoplasmic transport machinery or regulate it indirectly, likely through interactions with other proteins and by intramolecular folding.
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Affiliation(s)
- Louisa M. Salemi
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Sandra O. Loureiro
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Caroline Schild-Poulter
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
- * E-mail:
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27
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Bao J, Tang C, Li J, Zhang Y, Bhetwal BP, Zheng H, Yan W. RAN-binding protein 9 is involved in alternative splicing and is critical for male germ cell development and male fertility. PLoS Genet 2014; 10:e1004825. [PMID: 25474150 PMCID: PMC4256260 DOI: 10.1371/journal.pgen.1004825] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 10/14/2014] [Indexed: 01/09/2023] Open
Abstract
As a member of the large Ran-binding protein family, Ran-binding protein 9 (RANBP9) has been suggested to play a critical role in diverse cellular functions in somatic cell lineages in vitro, and this is further supported by the neonatal lethality phenotype in Ranbp9 global knockout mice. However, the exact molecular actions of RANBP9 remain largely unknown. By inactivation of Ranbp9 specifically in testicular somatic and spermatogenic cells, we discovered that Ranbp9 was dispensable for Sertoli cell development and functions, but critical for male germ cell development and male fertility. RIP-Seq and proteomic analyses revealed that RANBP9 was associated with multiple key splicing factors and directly targeted >2,300 mRNAs in spermatocytes and round spermatids. Many of the RANBP9 target and non-target mRNAs either displayed aberrant splicing patterns or were dysregulated in the absence of Ranbp9. Our data uncovered a novel role of Ranbp9 in regulating alternative splicing in spermatogenic cells, which is critical for normal spermatogenesis and male fertility. Male fertility depends on successful production of functional sperm. Sperm are produced through spermatogenesis, a process of male germ cell proliferation and differentiation in the testis. Most of the genes involved in spermatogenesis are transcribed and processed into multiple isoforms, which are mainly achieved through alternative splicing. The testis-specific transcriptome, characterized by male germ cell-specific alternative splicing patterns, has been shown to be essential for successful spermatogenesis. However, how these male germ cells-specific alternative splicing events are regulated remains largely unknown. Here, we report that RANBP9 is involved in alternative splicing events that are critical for male germ cell development, and dysfunction of RANBP9 leads to disrupted spermatogenesis and compromised male fertility.
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Affiliation(s)
- Jianqiang Bao
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
| | - Chong Tang
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
| | - Jiachen Li
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
| | - Ying Zhang
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
| | - Bhupal P. Bhetwal
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
| | - Huili Zheng
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
| | - Wei Yan
- Department of Physiology and Cell Biology, University of Nevada Reno School of Medicine, Reno, Nevada, United States of America
- * E-mail:
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28
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Tripathi BK, Lowy DR, Zelenka PS. The Cdk5 activator P39 specifically links muskelin to myosin II and regulates stress fiber formation and actin organization in lens. Exp Cell Res 2014; 330:186-98. [PMID: 25128817 DOI: 10.1016/j.yexcr.2014.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/31/2014] [Accepted: 08/02/2014] [Indexed: 10/24/2022]
Abstract
Cyclin dependent kinase 5 (Cdk5), a proline-directed serine/threonine kinase, requires p39 for its enzymatic activity, and is implicated in cytoskeletal organization and contraction in numerous cell types. The C-terminus of p39 binds muskelin, a multi-domain scaffolding protein known to affect cytoskeletal organization, but the mechanisms by which muskelin affects cytoskeletal organization remain unclear. The present study sought to determine whether p39 might serve as an adaptor protein that links muskelin to stress fibers and to investigate the possible biological relevance of such an interaction. Double immunoprecipitation showed that muskelin, p39, and myosin II are components of a single intracellular complex, and suppressing p39 abrogated the interaction between muskelin and the myosin subunits, demonstrating that p39 is required to link muskelin to myosin II. Muskelin is colocalized with myosin regulatory light chain (MRLC) and on stress fibers. The suppression of muskelin reduced Rho-GTP, MRLC phosphorylation, disrupted stress fiber organization, and promoted cell migration, all of which closely mimic the effect of Cdk5 inhibition. Moreover, suppressing muskelin and inhibiting Cdk5 together have no additional effect, indicating that muskelin plays an important role in Cdk5-dependent signaling. p39 is necessary and sufficient for Cdk5-dependent regulation of MRLC phosphorylation, as suppression of p39, but not p35, reduces MRLC phosphorylation. Together, these results demonstrate that p39 specifically links muskelin to myosin II and consequently, to stress fibers and reveal a novel role for muskelin in regulating myosin phosphorylation and cytoskeletal organization.
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Affiliation(s)
- Brajendra K Tripathi
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Building 37, Room 4112, Bethesda, MD 20892, USA; Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Douglas R Lowy
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Building 37, Room 4112, Bethesda, MD 20892, USA
| | - Peggy S Zelenka
- Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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29
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RanBP9 overexpression reduces dendritic arbor and spine density. Neuroscience 2014; 265:253-62. [PMID: 24486966 DOI: 10.1016/j.neuroscience.2014.01.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 01/22/2014] [Accepted: 01/22/2014] [Indexed: 11/21/2022]
Abstract
RanBP9 is a multi-domain scaffolding protein known to integrate extracellular signaling with intracellular targets. We previously demonstrated that RanBP9 enhances Aβ generation and amyloid plaque burden which results in loss of specific pre- and postsynaptic proteins in vivo in a transgenic mouse model. Additionally, we showed that the levels of spinophilin, a marker of dendritic spines were inversely proportional to the RanBP9 protein levels within the synaptosomes isolated from AD brains. In the present study, we found reduced dendritic intersections within the layer 6 pyramidal neurons of the cortex as well as the hippocampus of RanBP9 transgenic mice compared to age-matched wild-type (WT) controls at 12 months of age but not at 6months. Similarly, the dendritic spine numbers were reduced in the cortex at only 12 months of age by 30% (p<0.01), but not at 6months. In the hippocampus also the spine densities were reduced at 12 months of age (38%, p<0.01) in the RanBP9 transgenic mice. Interestingly, the levels of phosphorylated form of cofilin, an actin binding protein that plays crucial role in the regulation of spine numbers were significantly decreased in the cortical synaptosomes at only 12months of age by 26% (p<0.01). In the hippocampal synaptosomes, the decrease in cofilin levels were 36% (p<0.01) at 12 months of age. Thus dendritic arbor and spine density were directly correlated to the levels of phosphorylated form of cofilin in the RanBP9 transgenic mice. Similarly, cortical synaptosomes showed a 20% (p<0.01) reduction in the levels of spinophilin in the RanBP9 transgenic mice. These results provided the physical basis for the loss of synaptic proteins by RanBP9 and most importantly it also explains the impaired spatial learning and memory skills previously observed in the RanBP9 transgenic mice.
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30
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Roh SE, Woo JA, Lakshmana MK, Uhlar C, Ankala V, Boggess T, Liu T, Hong YH, Mook-Jung I, Kim SJ, Kang DE. Mitochondrial dysfunction and calcium deregulation by the RanBP9-cofilin pathway. FASEB J 2013; 27:4776-89. [PMID: 23982146 DOI: 10.1096/fj.13-234765] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mitochondrial dysfunction and synaptic damage are important features of Alzheimer's disease (AD) associated with amyloid β (Aβ) and tau. We reported previously that the scaffolding protein RanBP9, which is overall increased in brains of patients with AD and in mutant APP transgenic mice, simultaneously promotes Aβ generation and focal adhesion disruption by accelerating the endocytosis of APP and β1-integrin, respectively. Moreover, RanBP9 induces neurodegeneration in vitro and in vivo and mediates Aβ-induced neurotoxicity. Here we show in primary hippocampal neurons that RanBP9 potentiates Aβ-induced reactive oxygen species (ROS) overproduction, apoptosis, and calcium deregulation. Analyses of calcium-handling measures demonstrate that RanBP9 selectively delays the clearance of cytosolic Ca(2+) mediated by the mitochondrial calcium uniporter through a process involving the translocation of cofilin into mitochondria and oxidative mechanisms. Further, RanBP9 retards the anterograde axonal transport of mitochondria in primary neurons and decreases synaptic mitochondrial activity in brain. These data indicate that RanBP9, cofilin, and Aβ mimic and potentiate each other to produce mitochondrial dysfunction, ROS overproduction, and calcium deregulation, which leads to neurodegenerative changes reminiscent of those seen in AD.
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Affiliation(s)
- Seung-Eon Roh
- 1Department of Molecular Medicine, USF Health Byrd Institute, 4001 E. Fletcher Ave., Tampa, FL 33613, USA.
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31
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Jeon JP, Roh SE, Wie J, Kim J, Kim H, Lee KP, Yang D, Jeon JH, Cho NH, Kim IG, Kang DE, Kim HJ, So I. Activation of TRPC4β by Gαi subunit increases Ca2+ selectivity and controls neurite morphogenesis in cultured hippocampal neuron. Cell Calcium 2013; 54:307-19. [PMID: 24011658 DOI: 10.1016/j.ceca.2013.07.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 07/27/2013] [Accepted: 07/29/2013] [Indexed: 11/16/2022]
Abstract
The ubiquitous transient receptor potential canonical (TRPC) channels function as non-selective, Ca(2+)-permeable channels. TRPC channels are activated by stimulation of Gαq-PLC-coupled receptors. Here, we report that TRPC4/TRPC5 can be activated by Gαi. We studied the essential role of Gαi subunits in TRPC4 activation and investigated changes in ion selectivity and pore dilation of the TRPC4 channel elicited by the Gαi2 subunit. Activation of TRPC4 by Gαi2 increased Ca2+ permeability and Ca2+ influx through TRPC4 channels. Co-expression of the muscarinic receptor (M2) and TRPC4 in HEK293 cells induced TRPC4-mediated Ca2+ influx. Moreover, both TRPC4β and the TRPC4β-Gαi2 signaling complex induced inhibition of neurite growth and arborization in cultured hippocampal neurons. Cells treated with KN-93, a CaMKII inhibitor, prevented TRPC4- and TRPC4-Gαi2(Q205L)-mediated inhibition of neurite branching and growth. These findings indicate an essential role of Gαi proteins in TRPC4 activation and extend our knowledge of the functional role of TRPC4 in hippocampal neurons.
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Affiliation(s)
- Jae-Pyo Jeon
- Department of Physiology and Institute of Dermatological Science, Seoul National University College of Medicine, Seoul 110-799, Republic of Korea
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32
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A C-Terminal Transmembrane Anchor Targets the Nuage-Localized Spermatogenic Protein Gasz to the Mitochondrial Surface. ACTA ACUST UNITED AC 2013; 2013. [PMID: 25419467 DOI: 10.1155/2013/707930] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mitochondria, normally tubular and distributed throughout the cell, are instead found in spermatocytes in perinuclear clusters in close association with nuage, an amorphous organelle composed of RNA and RNA-processing proteins that generate piRNAs. piRNAs are a form of RNAi required for transposon suppression and ultimately fertility. MitoPLD, another protein required for piRNA production, is anchored to the mitochondrial surface, suggesting that the nuage, also known as intermitochondrial cement, needs to be juxtaposed there to bring MitoPLD into proximity with the remainder of the piRNA-generating machinery. However, the mechanism underlying the juxtaposition is unknown. Gasz, a multidomain protein of known function found in the nuage in vertebrates, is required for piRNA production and interacts with other nuage proteins involved in this pathway. Unexpectedly, we observed that Gasz, in nonspermatogenic mammalian cells lines, localizes to mitochondria and does so through a previously unrecognized conserved C-terminal mitochondrial targeting sequence. Moreover, in this setting, Gasz is able to recruit some of the normally nuage-localized proteins to the mitochondrial surface. Taken together, these findings suggest that Gasz is a nuage-localized protein in spermatocytes that facilitates anchoring of the nuage to the mitochondrial surface where piRNA generation takes place as a collaboration between nuage and mitochondrial-surface proteins.
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33
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Palavicini JP, Lloyd BN, Hayes CD, Bianchi E, Kang DE, Dawson-Scully K, Lakshmana MK. RanBP9 Plays a Critical Role in Neonatal Brain Development in Mice. PLoS One 2013; 8:e66908. [PMID: 23840553 PMCID: PMC3694151 DOI: 10.1371/journal.pone.0066908] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 05/10/2013] [Indexed: 11/29/2022] Open
Abstract
RanBP9 is known to act as a scaffolding protein bringing together a variety of cell surface receptors and intracellular targets thereby regulating functions as diverse as neurite and axonal outgrowth, cell morphology, cell proliferation, myelination, gonad development, myofibrillogenesis and migration of neuronal precursors. Though RanBP9 is ubiquitously expressed in all tissues, brain is one of the organs with the highest expression levels of RanBP9. In the neurons, RanBP9 is localized mostly in the cytoplasm but also in the neurites and dendritic processes. We recently demonstrated that RanBP9 plays pathogenic role in Alzheimer’s disease. To understand the role of RanBP9 in the brain, here we generated RanBP9 null mice by gene-trap based strategy. Most of Ran−/− mice die neonatally due to defects in the brain growth and development. The major defects include smaller cortical plate (CP), robustly enlarged lateral ventricles (LV) and reduced volume of hippocampus (HI). The lethal phenotype is due to a suckling defect as evidenced by lack of milk in the stomachs even several hours after parturition. The complex somatosensory system which is required for a behavior such as suckling appears to be compromised in Ran−/− mice due to under developed CP. Most importantly, RanBP9 phenotype is similar to ERK1/2 double knockout and the neural cell adhesion receptor, L1CAM knockout mice. Both ERK1 and L1CAM interact with RanBP9. Thus, RanBP9 appears to control brain growth and development through signaling mechanisms involving ERK1 and L1CAM receptor.
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Affiliation(s)
- Juan Pablo Palavicini
- Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida, United States of America
| | - Brandon Noel Lloyd
- Department of Biological Sciences, Charles E. Schmidt College of Science, Florida Atlantic University, Boca Raton, Florida, United States of America
| | - Crystal D. Hayes
- Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida, United States of America
| | - Elisabetta Bianchi
- Laboratory of Immuneregulation, Department of Immunology, Institut Pasteur, Paris, France
| | - David E. Kang
- Department of Molecular Medicine, USF Health Byrd Alzheimer’s Institute, Tampa, Florida, United States of America
| | - Ken Dawson-Scully
- Department of Biological Sciences, Charles E. Schmidt College of Science, Florida Atlantic University, Boca Raton, Florida, United States of America
| | - Madepalli K. Lakshmana
- Section of Neurobiology, Torrey Pines Institute for Molecular Studies, Port Saint Lucie, Florida, United States of America
- * E-mail:
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34
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RanBP9 aggravates synaptic damage in the mouse brain and is inversely correlated to spinophilin levels in Alzheimer's brain synaptosomes. Cell Death Dis 2013; 4:e667. [PMID: 23764848 PMCID: PMC3698550 DOI: 10.1038/cddis.2013.183] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We previously demonstrated that overexpression of RanBP9 led to enhanced Aβ generation in a variety of cell lines and primary neuronal cultures, and subsequently, we confirmed increased amyloid plaque burden in a mouse model of Alzheimer's disease (AD). In the present study, we found striking reduction of spinophilin protein levels when RanBP9 is overexpressed. At 12 months of age, we found spinophilin levels reduced by 70% (P<0.001) in the cortex of APΔE9/RanBP9 mice compared with that in wild-type (WT) controls. In the hippocampus, the spinophilin levels were reduced by 45% (P<0.01) in the APΔE9/RanBP9 mice. Spinophilin immunoreactivity was also reduced by 22% (P<0.01) and 12% (P<0.05) in the cortex of APΔE9/RanBP9 and APΔE9 mice, respectively. In the hippocampus, the reductions were 27% (P<0.001) and 14% (P<0.001) in the APΔE9/RanBP9 and APΔE9 mice, respectively. However, in the cerebellum, spinophilin levels were not altered in either APΔE9 or APΔE9/RanBP9 mice. Additionally, synaptosomal functional integrity was reduced under basal conditions by 39% (P<0.001) in the APΔE9/RanBP9 mice and ∼23% (P<0.001) in the APΔE9 mice compared with that in WT controls. Under ATP- and KCl-stimulated conditions, we observed higher mitochondrial activity in the WT and APΔE9 mice, but lower in the APΔE9/RanBP9 mice. Significantly, we confirmed the inverse relationship between RanBP9-N60 and spinophilin in the synaptosomes of Alzheimer's brains. More importantly, both APΔE9 and APΔE9/RanBP9 mice showed impaired learning and memory skills compared to WT controls. These data suggest that RanBP9 might play a crucial role in the loss of spines and synapses in AD.
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Liu T, Roh SE, Woo JA, Ryu H, Kang DE. Cooperative role of RanBP9 and P73 in mitochondria-mediated apoptosis. Cell Death Dis 2013; 4:e476. [PMID: 23348590 PMCID: PMC3563991 DOI: 10.1038/cddis.2012.203] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mitochondrial dysfunction and synaptic damage are critical early features of Alzheimer's disease (AD) associated with amyloid β (Aβ) and τ. We previously reported that the scaffolding protein RanBP9, which is overall increased in AD, simultaneously promotes Aβ generation and focal adhesion disruption by accelerating the endocytosis of APP and β1-integrin, respectively. Moreover, RanBP9 induces neurodegeneration in vitro and in vivo and mediates Aβ-induced neurotoxicity. However, little is known regarding the mechanisms underlying such neurotoxic processes. Here, we show that RanBP9 induces the loss of mitochondrial membrane potential and increase in mitochondrial superoxides associated with decrease in Bcl-2, increase in Bax protein and oligomerization, fragmentation of mitochondria, and cytochrome c release. RanBP9-induced neurotoxic changes are significantly prevented by the mitochondrial fission inhibitor Mdivi-1 and by classical inhibitors of the mitochondrial apoptosis, XIAP, Bcl-2, and Bcl-xl. RanBP9 physically interacts with the tumor suppressor p73 and increases endogenous p73α levels at both transcriptional and post-translational levels;moreover, the knockdown of endogenous p73 by siRNA effectively blocks RanBP9 and Aβ1-42-induced mitochondria-mediated cell death. Conversely, siRNA knockdown of endogenous RanBP9 also suppresses p73-induced apoptosis, suggesting that RanBP9 and p73 have cooperative roles in inducing cell death. Taken together, these finding implicate the RanBP9/p73 complex in mitochondria-mediated apoptosis in addition to its role in enhancing Aβ generation.
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Affiliation(s)
- T Liu
- WCU-Neurocytomics Program, Seoul National University College of Medicine, Seoul, Korea
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Esteves SLC, Korrodi-Gregório L, Cotrim CZ, van Kleeff PJM, Domingues SC, da Cruz e Silva OAB, Fardilha M, da Cruz e Silva EF. Protein phosphatase 1γ isoforms linked interactions in the brain. J Mol Neurosci 2012; 50:179-97. [PMID: 23080069 DOI: 10.1007/s12031-012-9902-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/03/2012] [Indexed: 01/03/2023]
Abstract
Posttranslational protein modifications, in particular reversible protein phosphorylation, are important regulatory mechanisms involved in cellular signaling transduction pathways. Thousands of human proteins are phosphorylatable and the tight regulation of phosphorylation states is crucial for cell maintenance and development. Protein phosphorylation occurs primarily on serine, threonine, and tyrosine residues, through the antagonistic actions of protein kinases and phosphatases. The catalytic subunit of protein phosphatase 1 (PP1), a major Ser/Thr-phosphatase, associates with a large variety of regulatory subunits that define substrate specificity and determine specific cellular pathway responses. PP1 has been shown to bind to different proteins in the brain in order to execute key and differential functions. This work reports the identification of proteins expressed in the human brain that interact with PP1γ1 and PP1γ2 isoforms by the yeast two-hybrid method. An extensive search of PP1-binding motifs was performed for the proteins identified, revealing already known PP1 regulators but also novel interactors. Moreover, our results were integrated with the data of PP1γ interacting proteins from several public web databases, permitting the development of physical maps of the novel interactions. The PP1γ interactome thus obtained allowed for the identification of novel PP1 interacting proteins, supporting novel functions of PP1γ isoforms in the human brain.
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Affiliation(s)
- Sara L C Esteves
- Signal Transduction Laboratory, Centre for Cell Biology, Biology Department, University of Aveiro, 3810-193 Aveiro, Portugal
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Atabakhsh E, Wang JH, Wang X, Carter DE, Schild-Poulter C. RanBPM expression regulates transcriptional pathways involved in development and tumorigenesis. Am J Cancer Res 2012; 2:549-565. [PMID: 22957307 PMCID: PMC3433104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 08/09/2012] [Indexed: 06/01/2023] Open
Abstract
RanBPM is a ubiquitous protein that has been reported to regulate several cellular processes through interactions with various proteins. However, it is not known whether RanBPM may regulate gene expression patterns. As it has been shown that RanBPM interacts with a number of transcription factors, we hypothesized that it may have wide ranging effects on gene expression that may explain its function. To test this hypothesis, we generated stable RanBPM shRNA cell lines to analyze the effect of RanBPM on global gene expression. Microarray analyses were conducted comparing the gene expression profile of Hela and HCT116 RanBPM shRNA cells versus control shRNA cells. We identified 167 annotated genes significantly up- or down-regulated in the two cell lines. Analysis of the gene set revealed that down-regulation of RanBPM led to gene expression changes that affect regulation of cell, tissue, and organ development and morphology, as well as biological processes implicated in tumorigenesis. Analysis of Transcription Factor Binding Sites (TFBS) present in the gene set identified several significantly over-represented transcription factors of the Forkhead, HMG, and Homeodomain families of transcription factors, which have previously been demonstrated as having important roles in development and tumorigenesis. In addition, the combined results of these analyses suggested that several signaling pathways were affected by RanBPM down-regulation, including ERK1/2, Wnt, Notch, and PI3K/Akt pathways. Lastly, analysis of selected target genes by quantitative RT-qPCR confirmed the changes revealed by microarray. Several of the genes up-regulated in RanBPM shRNA cells encode proteins with known oncogenic functions, such as the RON tyrosine kinase, the adhesion molecule L1CAM, and transcription factor ELF3/ESE-1, suggesting that RanBPM functions as a tumor suppressor to prevent deregulated expression of these genes. Altogether, these results suggest that RanBPM does indeed function to regulate many genomic events that regulate embryonic, tissue, and cellular development as well as those involved in cancer development and progression.
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Affiliation(s)
- Elnaz Atabakhsh
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University London, Ontario, N6A 5K8, Canada
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Pivotal role of the RanBP9-cofilin pathway in Aβ-induced apoptosis and neurodegeneration. Cell Death Differ 2012; 19:1413-23. [PMID: 22361682 DOI: 10.1038/cdd.2012.14] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Neurodegeneration associated with amyloid β (Aβ) peptide accumulation, synaptic loss, neuroinflammation, tauopathy, and memory impairments encompass the pathophysiological features of Alzheimer's disease (AD). We previously reported that the scaffolding protein RanBP9, which is overall increased in brains of AD patients, simultaneously promotes Aβ generation and focal adhesion disruption by accelerating the endocytosis of amyloid precursor protein (APP) and β1-integrin, respectively. Here, we show that RanBP9 protein levels are increased by fourfold in FAD mutant APP transgenic mice. Accordingly, RanBP9 transgenic mice demonstrate significantly increased synapse loss, neurodegeneration, gliosis, and spatial memory deficits. RanBP9 overexpression promotes apoptosis and potentiates Aβ-induced neurotoxicity independent of its capacity to promote Aβ generation. Conversely, RanBP9 reduction by siRNA or gene dosage mitigates Aβ-induced neurotoxicity. Importantly, RanBP9 activates/dephosphorylates cofilin, a key regulator of actin dynamics and mitochondria-mediated apoptosis, and siRNA knockdown of cofilin abolishes both Aβ and RanBP9-induced apoptosis. These findings implicate the RanBP9-cofilin pathway as critical therapeutic targets not only for stemming Aβ generation but also antagonizing Aβ-induced neurotoxicity.
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