1
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Koehn OJ, Lorimer E, Unger B, Harris R, Das AS, Suazo KF, Auger S, Distefano M, Prokop JW, Williams CL. GTPase splice variants RAC1 and RAC1B display isoform-specific differences in localization, prenylation, and interaction with the chaperone protein SmgGDS. J Biol Chem 2023; 299:104698. [PMID: 37059183 DOI: 10.1016/j.jbc.2023.104698] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 04/04/2023] [Accepted: 04/06/2023] [Indexed: 04/16/2023] Open
Abstract
Identifying events that regulate the prenylation and localization of small GTPases will help define new strategies for therapeutic targeting of these proteins in disorders such as cancer, cardiovascular disease, and neurological deficits. Splice variants of the chaperone protein SmgGDS (encoded by RAP1GDS1) are known to regulate prenylation and trafficking of small GTPases. The SmgGDS-607 splice variant regulates prenylation by binding pre-prenylated small GTPases, but the effects of SmgGDS binding to the small GTPase RAC1 versus the splice variant RAC1B are not well defined. Here we report unexpected differences in the prenylation and localization of RAC1 and RAC1B, and their binding to SmgGDS. Compared to RAC1, RAC1B more stably associates with SmgGDS-607, is less prenylated, and accumulates more in the nucleus. We show that the small GTPase DIRAS1 inhibits binding of RAC1 and RAC1B to SmgGDS and reduces their prenylation. These results suggest that prenylation of RAC1 and RAC1B is facilitated by binding to SmgGDS-607, but the greater retention of RAC1B by SmgGDS-607 slows RAC1B prenylation. We show that inhibiting RAC1 prenylation by mutating the CAAX motif promotes RAC1 nuclear accumulation, suggesting that differences in prenylation contribute to the different nuclear localization of RAC1 versus RAC1B. Finally, we demonstrate RAC1 and RAC1B that cannot be prenylated bind GTP in cells, indicating that prenylation is not a prerequisite for activation. We report differential expression of RAC1 and RAC1B transcripts in tissues, consistent with these two splice variants having unique functions that might arise in part from their differences in prenylation and localization.
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Affiliation(s)
- Olivia J Koehn
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Ellen Lorimer
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Bethany Unger
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Ra'Mal Harris
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI, 49503, USA
| | - Akansha S Das
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI, 49503, USA
| | - Kiall F Suazo
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USAA
| | - Shelby Auger
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USAA
| | - Mark Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USAA
| | - Jeremy W Prokop
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI, 49503, USA; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, 48824, USA
| | - Carol L Williams
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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2
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Haney SL, Holstein SA. Targeting the Isoprenoid Biosynthetic Pathway in Multiple Myeloma. Int J Mol Sci 2022; 24:ijms24010111. [PMID: 36613550 PMCID: PMC9820492 DOI: 10.3390/ijms24010111] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/13/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Multiple myeloma (MM) is a plasma cell malignancy for which there is currently no cure. While treatment options for MM have expanded over the last two decades, all patients will eventually become resistant to current therapies. Thus, there is an urgent need for novel therapeutic strategies to treat MM. The isoprenoid biosynthetic pathway (IBP) is responsible for the post-translational modification of proteins belonging to the Ras small GTPase superfamily, such as Ras, Rho and Rab family members. Given the important roles these GTPase proteins play in various cellular processes, there is significant interest in the development of inhibitors that disturb their prenylation and consequently their activity in MM cells. Numerous preclinical studies have demonstrated that IBP inhibitors have anti-MM effects, including the induction of apoptosis in MM cells and inhibition of osteoclast activity. Some IBP inhibitors have made their way into the clinic. For instance, nitrogenous bisphosphonates are routinely prescribed for the management MM bone disease. Other IBP inhibitors, including statins and farnesyltransferase inhibitors, have been evaluated in clinical trials for MM, while there is substantial preclinical investigation into geranylgeranyl diphosphate synthase inhibitors. Here we discuss recent advances in the development of IBP inhibitors, assess their mechanism of action and evaluate their potential as anti-MM agents.
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3
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Pharmacological inhibition of Rac1 attenuates myocardial abnormalities in tail-suspended mice. J Cardiovasc Transl Res 2022; 15:805-815. [DOI: 10.1007/s12265-021-10197-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 12/13/2021] [Indexed: 11/25/2022]
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4
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Abstract
Rho guanosine triphosphatase (GTPases), as molecular switches, have been identified to be dysregulated and involved in the pathogenesis of various rheumatic diseases, mainly including rheumatoid arthritis, osteoarthritis, systemic sclerosis, and systemic lupus erythematosus. Downstream pathways involving multiple types of cells, such as fibroblasts, chondrocytes, synoviocytes, and immunocytes are mediated by activated Rho GTPases to promote pathogenesis. Targeted therapy via inhibitors of Rho GTPases has been implicated in the treatment of rheumatic diseases, demonstrating promising effects. In this review, the effects of Rho GTPases in the pathogenesis of rheumatic diseases are summarized, and the Rho GTPase-mediated pathways are elucidated. Therapeutic strategies using Rho GTPase inhibitors in rheumatic diseases are also discussed to provide insights for further exploration of targeted therapy in preclinical studies and clinical practice. Future directions on studies of Rho GTPases in rheumatic diseases based on current understandings are provided.
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Affiliation(s)
- Ruijie Zeng
- Department of Gastroenterology, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou 510080, China
- Shantou University Medical College, Shantou 515041, China
| | - Zewei Zhuo
- Department of Gastroenterology, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou 510080, China
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China
| | - Yujun Luo
- Department of Gastroenterology, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou 510080, China
| | - Weihong Sha
- Department of Gastroenterology, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou 510080, China
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou 510515, China
- School of Medicine, South China University of Technology, Guangzhou 510006, China
- Corresponding author
| | - Hao Chen
- Department of Gastroenterology, Guangdong Academy of Medical Sciences, Guangdong Provincial People's Hospital, Guangzhou 510080, China
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou 510515, China
- School of Medicine, South China University of Technology, Guangzhou 510006, China
- Corresponding author
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5
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Wen Q, Weng H, Liu T, Yu L, Zhao T, Qin J, Li S, Wu Q, Fadel T, Qu Y, Zhou L. Inactivating Celsr2 promotes motor axon fasciculation and regeneration in mouse and human. Brain 2022; 145:670-683. [PMID: 34983065 PMCID: PMC9014747 DOI: 10.1093/brain/awab317] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 07/20/2021] [Accepted: 07/26/2021] [Indexed: 11/18/2022] Open
Abstract
Understanding new modulators of axon regeneration is central to neural repair. Our previous work demonstrated critical roles of atypical cadherin Celsr2 during neural development, including cilia organization, neuron migration and axon navigation. Here, we address its role in axon regeneration. We show that Celsr2 is highly expressed in both mouse and human spinal motor neurons. Celsr2 knockout promotes axon regeneration and fasciculation in mouse cultured spinal explants. Similarly, cultured Celsr2 mutant motor neurons extend longer neurites and larger growth cones, with increased expression of end-binding protein 3 and higher potassium-induced calcium influx. Mice with Celsr2 conditional knockout in spinal motor neurons do not exhibit any behavioural deficits; however, after branchial plexus injury, axon regeneration and functional forelimb locomotor recovery are significantly improved. Similarly, knockdown of CELSR2 using shRNA interference in cultured human spinal motor explants and motor neurons increases axonal fasciculation and growth. In mouse adult spinal cord after root avulsion, in mouse embryonic spinal cords, and in cultured human motor neurons, Celsr2 downregulation is accompanied by increased levels of GTP-bound Rac1 and Cdc42, and of JNK and c-Jun. In conclusion, Celsr2 negatively regulates motor axon regeneration and is a potential target to improve neural repair.
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Affiliation(s)
- Quan Wen
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou 510632, P. R. China
| | - Huandi Weng
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou 510632, P. R. China
| | - Tao Liu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou 510632, P. R. China
| | - Lingtai Yu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou 510632, P. R. China
| | - Tainyun Zhao
- Department of Anesthesiology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, P.R. China
| | - Jingwen Qin
- Department of Anesthesiology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, P.R. China
| | - Si Li
- State Key Laboratory of Molecular Development Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, P.R. China.,University of Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Qingfeng Wu
- State Key Laboratory of Molecular Development Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, P.R. China.,University of Chinese Academy of Sciences, Beijing 100101, P.R. China
| | - Tissir Fadel
- Université catholique de Louvain, Institute of Neuroscience, Developmental Neurobiology, Brussels, Belgium.,College of Life and Health Sciences, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Yibo Qu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou 510632, P. R. China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain- Inspired Intelligence, Guangzhou 510515, P.R. China.,Co-innovation Center of Neuroregeneration, Nantong University, Jiangsu, P. R. China
| | - Libing Zhou
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Ministry of Education CNS Regeneration Collaborative Joint Laboratory, Jinan University, Guangzhou 510632, P. R. China.,Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, P.R. China.,Co-innovation Center of Neuroregeneration, Nantong University, Jiangsu, P. R. China.,The first affiliated hospital of Jian University, Guangzhou 510632, P. R. China
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6
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Eroumé KS, Cavill R, Staňková K, de Boer J, Carlier A. Exploring the influence of cytosolic and membrane FAK activation on YAP/TAZ nuclear translocation. Biophys J 2021; 120:4360-4377. [PMID: 34509508 PMCID: PMC8553670 DOI: 10.1016/j.bpj.2021.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/16/2021] [Accepted: 09/07/2021] [Indexed: 11/12/2022] Open
Abstract
Membrane binding and unbinding dynamics play a crucial role in the biological activity of several nonintegral membrane proteins, which have to be recruited to the membrane to perform their functions. By localizing to the membrane, these proteins are able to induce downstream signal amplification in their respective signaling pathways. Here, we present a 3D computational approach using reaction-diffusion equations to investigate the relation between membrane localization of focal adhesion kinase (FAK), Ras homolog family member A (RhoA), and signal amplification of the YAP/TAZ signaling pathway. Our results show that the theoretical scenarios in which FAK is membrane bound yield robust and amplified YAP/TAZ nuclear translocation signals. Moreover, we predict that the amount of YAP/TAZ nuclear translocation increases with cell spreading, confirming the experimental findings in the literature. In summary, our in silico predictions show that when the cell membrane interaction area with the underlying substrate increases, for example, through cell spreading, this leads to more encounters between membrane-bound signaling partners and downstream signal amplification. Because membrane activation is a motif common to many signaling pathways, this study has important implications for understanding the design principles of signaling networks.
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Affiliation(s)
- Kerbaï Saïd Eroumé
- MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands
| | - Rachel Cavill
- Department of Data Science and Knowledge Engineering, Faculty of Science and Engineering, Maastricht University, Maastricht, the Netherlands
| | - Katerina Staňková
- Department of Data Science and Knowledge Engineering, Faculty of Science and Engineering, Maastricht University, Maastricht, the Netherlands
| | - Jan de Boer
- Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Aurélie Carlier
- MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, the Netherlands.
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7
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Momenzadeh S, Zamani S, Dehghan F, Barreiro C, Jami MS. Comparative proteome analyses highlight several exercise-like responses of mouse sciatic nerve after IP injection of irisin. Eur J Neurosci 2021; 53:3263-3278. [PMID: 33759230 DOI: 10.1111/ejn.15202] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 02/19/2021] [Accepted: 03/12/2021] [Indexed: 12/16/2022]
Abstract
Many beneficial effects of exercise on the nervous system are mediated by hormone (growth factor)/receptor signaling. Considering the accumulating evidence on the similarity of some beneficial effects, irisin can be a proposed effector of exercise; however, the mechanism underlying these effects remains largely unknown. More evidence on the mechanism of action might reveal its potential as a treatment strategy to substitute exercise recovery protocols for nerve injuries in physically disabled patients. To evaluate the underlying mechanism of irisin involvement in nerve adaptation and exerting beneficial effects, we studied the proteome profile alteration of mouse sciatic nerve after irisin administration. We also compared it with two 8-week protocols of resistance exercise and endurance exercise. The results indicate that irisin contributes to the regulation of nerve metabolism via overexpression of Ckm and ATP5j2 proteins. Irisin administration may improve sciatic nerve function by maintaining the architecture, enhancing axonal transport, and promoting synapse plasticity through increased structural and regulatory proteins and NO production. We also showed that irisin has the potential to induce neurotrophic support on the sciatic nerve by maintaining cell redox homeostasis, and responses to oxidative stress via the upregulation of disulfide-isomerase and superoxide dismutase enzymes. Comparing with exercise groups, these effects are somewhat exercise-like responses. These data suggest that irisin can be a promising therapeutic candidate for specific targeting of defects in peripheral neuropathies and nerve injuries as an alternative for physical therapy.
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Affiliation(s)
- Sedigheh Momenzadeh
- Department of Medical Biotechnology, School of Advanced Technologies, Shahrekord University of Medical Sciences, Shahrekord, Iran.,Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Saeed Zamani
- Department of Anatomical Sciences, School of Medicine, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Fariba Dehghan
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Carlos Barreiro
- 5 INBIOTEC (Instituto de Biotecnología de León), León, Spain.,Departamento de Biología Molecular, Universidad de León, Ponferrada, Spain
| | - Mohammad-Saeid Jami
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran.,Department of Neurology, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, USA
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8
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MMP-9 Signaling Pathways That Engage Rho GTPases in Brain Plasticity. Cells 2021; 10:cells10010166. [PMID: 33467671 PMCID: PMC7830260 DOI: 10.3390/cells10010166] [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: 12/18/2020] [Revised: 01/12/2021] [Accepted: 01/12/2021] [Indexed: 02/08/2023] Open
Abstract
The extracellular matrix (ECM) has been identified as a critical factor affecting synaptic function. It forms a functional scaffold that provides both the structural support and the reservoir of signaling molecules necessary for communication between cellular constituents of the central nervous system (CNS). Among numerous ECM components and modifiers that play a role in the physiological and pathological synaptic plasticity, matrix metalloproteinase 9 (MMP-9) has recently emerged as a key molecule. MMP-9 may contribute to the dynamic remodeling of structural and functional plasticity by cleaving ECM components and cell adhesion molecules. Notably, MMP-9 signaling was shown to be indispensable for long-term memory formation that requires synaptic remodeling. The core regulators of the dynamic reorganization of the actin cytoskeleton and cell adhesion are the Rho family of GTPases. These proteins have been implicated in the control of a wide range of cellular processes occurring in brain physiology and pathology. Here, we discuss the contribution of Rho GTPases to MMP-9-dependent signaling pathways in the brain. We also describe how the regulation of Rho GTPases by post-translational modifications (PTMs) can influence these processes.
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9
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Shabanzadeh AP, Charish J, Tassew NG, Farhani N, Feng J, Qin X, Sugita S, Mothe AJ, Wälchli T, Koeberle PD, Monnier PP. Cholesterol synthesis inhibition promotes axonal regeneration in the injured central nervous system. Neurobiol Dis 2021; 150:105259. [PMID: 33434618 DOI: 10.1016/j.nbd.2021.105259] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 12/24/2020] [Accepted: 01/07/2021] [Indexed: 12/12/2022] Open
Abstract
Neuronal regeneration in the injured central nervous system is hampered by multiple extracellular proteins. These proteins exert their inhibitory action through interactions with receptors that are located in cholesterol rich compartments of the membrane termed lipid rafts. Here we show that cholesterol-synthesis inhibition prevents the association of the Neogenin receptor with lipid rafts. Furthermore, we show that cholesterol-synthesis inhibition enhances axonal growth both on inhibitory -myelin and -RGMa substrates. Following optic nerve injury, lowering cholesterol synthesis with both drugs and siRNA-strategies allows for robust axonal regeneration and promotes neuronal survival. Cholesterol inhibition also enhanced photoreceptor survival in a model of Retinitis Pigmentosa. Our data reveal that Lovastatin leads to several opposing effects on regenerating axons: cholesterol synthesis inhibition promotes regeneration whereas altered prenylation impairs regeneration. We also show that the lactone prodrug form of lovastatin has differing effects on regeneration when compared to the ring-open hydroxy-acid form. Thus the association of cell surface receptors with lipid rafts contributes to axonal regeneration inhibition, and blocking cholesterol synthesis provides a potential therapeutic approach to promote neuronal regeneration and survival in the diseased Central Nervous System. SIGNIFICANCE STATEMENT: Statins have been intensively used to treat high levels of cholesterol in humans. However, the effect of cholesterol inhibition in both the healthy and the diseased brain remains controversial. In particular, it is unclear whether cholesterol inhibition with statins can promote regeneration and survival following injuries. Here we show that late stage cholesterol inhibition promotes robust axonal regeneration following optic nerve injury. We identified distinct mechanisms of action for activated vs non-activated Lovastatin that may account for discrepancies found in the literature. We show that late stage cholesterol synthesis inhibition alters Neogenin association with lipid rafts, thereby i) neutralizing the inhibitory function of its ligand and ii) offering a novel opportunity to promote CNS regeneration and survival following injuries.
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Affiliation(s)
- Alireza P Shabanzadeh
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada; Department of Physiology, Donald K. Johnson Research Institute, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada; Department of Anatomy, Faculty of Medicine, University of Toronto, Toronto M5S 1A8, Ontario, Canada
| | - Jason Charish
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada; Department of Physiology, Faculty of Medicine, University of Toronto, Toronto M5S 1A8, Ontario, Canada
| | - Nardos G Tassew
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada; Department of Physiology, Donald K. Johnson Research Institute, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada
| | - Nahal Farhani
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada
| | - Jinzhou Feng
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Xinjue Qin
- Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Shuzo Sugita
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada
| | - Andrea J Mothe
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada
| | - Thomas Wälchli
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada
| | - Paulo D Koeberle
- Department of Anatomy, Faculty of Medicine, University of Toronto, Toronto M5S 1A8, Ontario, Canada
| | - Philippe P Monnier
- Krembil Research Institute, KDT 8-417, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada; Department of Physiology, Donald K. Johnson Research Institute, 60 Leonard St., Toronto M5T 2S8, Ontario, Canada; Department of Ophthalmology, Faculty of Medicine, University of Toronto, Toronto M5S 1A8, Ontario, Canada; Department of Physiology, Faculty of Medicine, University of Toronto, Toronto M5S 1A8, Ontario, Canada.
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10
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Ötzkan S, Muller WE, Gibson Wood W, Eckert GP. Effects of 7,8-Dihydroxyflavone on Lipid Isoprenoid and Rho Protein Levels in Brains of Aged C57BL/6 Mice. Neuromolecular Med 2020; 23:130-139. [PMID: 33377988 PMCID: PMC7929957 DOI: 10.1007/s12017-020-08640-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/25/2020] [Indexed: 12/13/2022]
Abstract
Synaptic impairment may be the main cause of cognitive dysfunction in brain aging that is probably due to a reduction in synaptic contact between the axonal buttons and dendritic spines. Rho proteins including the small GTPase Rac1 have become key regulators of neuronal morphogenesis that supports synaptic plasticity. Small Rho- and Ras-GTPases are post-translationally modified by the isoprenoids geranylgeranyl pyrophosphate (GGPP) and farnesyl pyrophosphate (FPP), respectively. For all GTPases, anchoring in the plasma membrane is essential for their activation by guanine nucleotide exchange factors (GEFs). Rac1-specific GEFs include the protein T lymphoma invasion and metastasis 1 (Tiam1). Tiam1 interacts with the TrkB receptor to mediate the brain-derived neurotrophic factor (BDNF)-induced activation of Rac1, resulting in cytoskeletal rearrangement and changes in cellular morphology. The flavonoid 7,8-dihydroxyflavone (7,8-DHF) acts as a highly affine-selective TrkB receptor agonist and causes the dimerization and autophosphorylation of the TrkB receptor and thus the activation of downstream signaling pathways. In the current study, we investigated the effects of 7,8-DHF on cerebral lipid isoprenoid and Rho protein levels in male C57BL/6 mice aged 3 and 23 months. Aged mice were daily treated with 100 mg/kg b.w. 7,8-DHF by oral gavage for 21 days. FPP, GGPP, and cholesterol levels were determined in brain tissue. In the same tissue, the protein content of Tiam1 and TrkB in was measured. The cellular localization of the small Rho-GTPase Rac1 and small Rab-GTPase Rab3A was studied in total brain homogenates and membrane preparations. We report the novel finding that 7,8-DHF restored levels of the Rho proteins Rac1 and Rab3A in membrane preparations isolated from brains of treated aged mice. The selective TrkB agonist 7,8-DHF did not affect BDNF and TrkB levels, but restored Tiam1 levels that were found to be reduced in brains of aged mice. FPP, GGPP, and cholesterol levels were significantly elevated in brains of aged mice but not changed by 7,8-DHF treatment. Hence, 7,8-DHF may be useful as pharmacological tool to treat age-related cognitive dysfunction although the underlying mechanisms need to be elucidated in detail.
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Affiliation(s)
- Sarah Ötzkan
- Department of Pharmacology, Biocenter Niederursel, University of Frankfurt, Goethe-University, Max-von-Laue-St. 9, 60438, Frankfurt, Germany
| | - Walter E Muller
- Department of Pharmacology, Biocenter Niederursel, University of Frankfurt, Goethe-University, Max-von-Laue-St. 9, 60438, Frankfurt, Germany
| | - W Gibson Wood
- Department of Pharmacology, Geriatric Research, Education and Clinical Center, University of Minnesota School of Medicine, VAMC, Minneapolis, MN, 55417, USA
| | - Gunter P Eckert
- Department of Pharmacology, Biocenter Niederursel, University of Frankfurt, Goethe-University, Max-von-Laue-St. 9, 60438, Frankfurt, Germany.
- Institute of Nutritional Sciences, Laboratory for Nutrition in Prevention and Therapy, Justus-Liebig-University of Giessen, Biomedical Research Center Seltersberg (BFS), Schubertstr. 81, 35392, Giessen, Germany.
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11
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Reddy JM, Raut NGR, Seifert JL, Hynds DL. Regulation of Small GTPase Prenylation in the Nervous System. Mol Neurobiol 2020; 57:2220-2231. [PMID: 31989383 DOI: 10.1007/s12035-020-01870-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 01/06/2020] [Indexed: 11/26/2022]
Abstract
Mevalonate pathway inhibitors have been extensively studied for their roles in cholesterol depletion and for inhibiting the prenylation and activation of various proteins. Inhibition of protein prenylation has potential therapeutic uses against neurological disorders, like neural cancers, neurodegeneration, and neurotramatic lesions. Protection against neurodegeneration and promotion of neuronal regeneration is regulated in large part by Ras superfamily small guanosine triphosphatases (GTPases), particularly the Ras, Rho, and Rab subfamilies. These proteins are prenylated to target them to cellular membranes. Prenylation can be specifically inhibited through altering the function of enzymes of the mevalonate pathway necessary for isoprenoid production and attachment to target proteins to elicit a variety of effects on neural cells. However, this approach does not address how prenylation affects a specific protein. This review focuses on the regulation of small GTPase prenylation, the different techniques to inhibit prenylation, and how this inhibition has affected neural cell processes.
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Affiliation(s)
| | | | | | - DiAnna L Hynds
- Texas Woman's University, Denton, TX, USA.
- Woodcock Institute for the Advancement of Neurocognitive Research and Applied Practice, Texas Woman's University, PO Box 4525799, Denton, TX, 76204-5799, USA.
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12
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Abdrabou A, Wang Z. Post-Translational Modification and Subcellular Distribution of Rac1: An Update. Cells 2018; 7:cells7120263. [PMID: 30544910 PMCID: PMC6316090 DOI: 10.3390/cells7120263] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/06/2018] [Accepted: 12/10/2018] [Indexed: 12/27/2022] Open
Abstract
Rac1 is a small GTPase that belongs to the Rho family. The Rho family of small GTPases is a subfamily of the Ras superfamily. The Rho family of GTPases mediate a plethora of cellular effects, including regulation of cytoarchitecture, cell size, cell adhesion, cell polarity, cell motility, proliferation, apoptosis/survival, and membrane trafficking. The cycling of Rac1 between the GTP (guanosine triphosphate)- and GDP (guanosine diphosphate)-bound states is essential for effective signal flow to elicit downstream biological functions. The cycle between inactive and active forms is controlled by three classes of regulatory proteins: Guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and guanine-nucleotide-dissociation inhibitors (GDIs). Other modifications include RNA splicing and microRNAs; various post-translational modifications have also been shown to regulate the activity and function of Rac1. The reported post-translational modifications include lipidation, ubiquitination, phosphorylation, and adenylylation, which have all been shown to play important roles in the regulation of Rac1 and other Rho GTPases. Moreover, the Rac1 activity and function are regulated by its subcellular distribution and translocation. This review focused on the most recent progress in Rac1 research, especially in the area of post-translational modification and subcellular distribution and translocation.
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Affiliation(s)
- Abdalla Abdrabou
- Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Zhixiang Wang
- Department of Medical Genetics, and Signal Transduction Research Group, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Reichova A, Zatkova M, Bacova Z, Bakos J. Abnormalities in interactions of Rho GTPases with scaffolding proteins contribute to neurodevelopmental disorders. J Neurosci Res 2017; 96:781-788. [DOI: 10.1002/jnr.24200] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 10/09/2017] [Accepted: 10/30/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Alexandra Reichova
- Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences; Bratislava Slovakia
| | - Martina Zatkova
- Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences; Bratislava Slovakia
- Institute of Physiology; Comenius University, Faculty of Medicine; Bratislava Slovakia
| | - Zuzana Bacova
- Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences; Bratislava Slovakia
- Department of Normal and Pathological Physiology, Faculty of Medicine; Slovak Medical University; Bratislava Slovakia
| | - Jan Bakos
- Biomedical Research Center, Institute of Experimental Endocrinology, Slovak Academy of Sciences; Bratislava Slovakia
- Institute of Physiology; Comenius University, Faculty of Medicine; Bratislava Slovakia
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14
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Interaction between Rho GTPases and 14-3-3 Proteins. Int J Mol Sci 2017; 18:ijms18102148. [PMID: 29036929 PMCID: PMC5666830 DOI: 10.3390/ijms18102148] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/11/2017] [Accepted: 10/13/2017] [Indexed: 01/25/2023] Open
Abstract
The Rho GTPase family accounts for as many as 20 members. Among them, the archetypes RhoA, Rac1, and Cdc42 have been the most well-characterized. Like all members of the small GTPases superfamily, Rho proteins act as molecular switches to control cellular processes by cycling between active, GTP-bound and inactive, GDP-bound states. The 14-3-3 family proteins comprise seven isoforms. They exist as dimers (homo- or hetero-dimer) in cells. They function by binding to Ser/Thr phosphorylated intracellular proteins, which alters the conformation, activity, and subcellular localization of their binding partners. Both 14-3-3 proteins and Rho GTPases regulate cell cytoskeleton remodeling and cell migration, which suggests a possible interaction between the signaling pathways regulated by these two groups of proteins. Indeed, more and more emerging evidence indicates the mutual regulation of these two signaling pathways. There have been many documented reviews of 14-3-3 protein and Rac1 separately, but there is no review regarding the interaction and mutual regulation of these two groups of proteins. Thus, in this article we thoroughly review all the reported interactions between the signaling pathways regulated by 14-3-3 proteins and Rho GTPases (mostly Rac1).
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15
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Tang Q, Jiang S, Jia W, Shen D, Qiu Y, Zhao Y, Xue B, Li C. Zoledronic acid, an FPPS inhibitor, ameliorates liver steatosis through inhibiting hepatic de novo lipogenesis. Eur J Pharmacol 2017; 814:169-177. [PMID: 28843826 DOI: 10.1016/j.ejphar.2017.08.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/09/2017] [Accepted: 08/09/2017] [Indexed: 02/07/2023]
Abstract
Currently, there is no standard therapy for non-alcoholic fatty liver disease (NAFLD), and statins have been developed as a first-line pharmaceutical therapeutic option for NAFLD-associated dyslipidemia. However, prolonged statins therapy has side effects, as statins inhibit HMG-CoA reductase, an enzyme at the very beginning of the mevalonate pathway. Here, we found that zoledronic acid (ZA), an inhibitor of farnesyl diphosphate synthase in the downstream mevalonate pathway, could attenuate hepatic lipid accumulation and improve liver injury in both high-fat diet-induced C57BL/6J mice and ob/ob mice. Moreover, the hepatic lipid metabolism was largely inhibited after ZA administration in high-fat diet-induced obese mice. Mechanically, ZA inhibited SREBP-1c-mediated de novo lipogenesis through suppressing RhoA activation via decreasing farnesyl diphosphate and geranylgeranyl diphosphate levels. In conclusion, our data provide a novel application of ZA in improving hepatic steatosis.
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Affiliation(s)
- Qiaoli Tang
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China
| | - Shan Jiang
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China; Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center and Nanjing University, Nanjing 210093, People's Republic of China
| | - Wenjun Jia
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China; Department of Hepatopancreatobiliary Surgery, The Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing 210008, People's Republic of China
| | - Di Shen
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China
| | - Yudong Qiu
- Department of Hepatopancreatobiliary Surgery, The Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing 210008, People's Republic of China
| | - Yue Zhao
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China.
| | - Bin Xue
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China.
| | - Chaojun Li
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China; Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center and Nanjing University, Nanjing 210093, People's Republic of China.
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16
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Li H, Kuwajima T, Oakley D, Nikulina E, Hou J, Yang WS, Lowry ER, Lamas NJ, Amoroso MW, Croft GF, Hosur R, Wichterle H, Sebti S, Filbin MT, Stockwell B, Henderson CE. Protein Prenylation Constitutes an Endogenous Brake on Axonal Growth. Cell Rep 2016; 16:545-558. [PMID: 27373155 DOI: 10.1016/j.celrep.2016.06.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 01/31/2016] [Accepted: 05/28/2016] [Indexed: 01/11/2023] Open
Abstract
Suboptimal axonal regeneration contributes to the consequences of nervous system trauma and neurodegenerative disease, but the intrinsic mechanisms that regulate axon growth remain unclear. We screened 50,400 small molecules for their ability to promote axon outgrowth on inhibitory substrata. The most potent hits were the statins, which stimulated growth of all mouse- and human-patient-derived neurons tested, both in vitro and in vivo, as did combined inhibition of the protein prenylation enzymes farnesyltransferase (PFT) and geranylgeranyl transferase I (PGGT-1). Compensatory sprouting of motor axons may delay clinical onset of amyotrophic lateral sclerosis (ALS). Accordingly, elevated levels of PGGT1B, which would be predicted to reduce sprouting, were found in motor neurons of early- versus late-onset ALS patients postmortem. The mevalonate-prenylation pathway therefore constitutes an endogenous brake on axonal growth, and its inhibition provides a potential therapeutic approach to accelerate neuronal regeneration in humans.
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Affiliation(s)
- Hai Li
- Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia Translational Neuroscience Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Neurology, and Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Takaaki Kuwajima
- Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia Translational Neuroscience Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Neurology, and Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Derek Oakley
- Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | - Elena Nikulina
- Department of Biological Sciences, Hunter College, City University of New York, NY 10065, USA
| | - Jianwei Hou
- Department of Biological Sciences, Hunter College, City University of New York, NY 10065, USA
| | - Wan Seok Yang
- Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia Translational Neuroscience Initiative, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute and Department of Biological Sciences and Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Emily Rhodes Lowry
- Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | - Nuno Jorge Lamas
- Department of Pathology and Cell Biology, Neurology, and Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA; Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, 4710-057 Braga, Minho, Portugal
| | | | - Gist F Croft
- Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | | | - Hynek Wichterle
- Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia Translational Neuroscience Initiative, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Neurology, and Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA
| | - Said Sebti
- Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, FL 33612, USA
| | - Marie T Filbin
- Department of Biological Sciences, Hunter College, City University of New York, NY 10065, USA
| | - Brent Stockwell
- Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia Translational Neuroscience Initiative, Columbia University, New York, NY 10032, USA; Howard Hughes Medical Institute and Department of Biological Sciences and Department of Chemistry, Columbia University, New York, NY 10027, USA
| | - Christopher E Henderson
- Center for Motor Neuron Biology and Disease, Columbia Stem Cell Initiative, Columbia Translational Neuroscience Initiative, Columbia University, New York, NY 10032, USA; Department of Rehabilitation and Regenerative Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Neurology, and Neuroscience, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA; Project A.L.S./Jenifer Estess Laboratory for Stem Cell Research, New York, NY 10032, USA; Target ALS Foundation, New York, NY 10032, USA.
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17
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Gao S, Yu R, Zhou X. The Role of Geranylgeranyltransferase I-Mediated Protein Prenylation in the Brain. Mol Neurobiol 2015; 53:6925-6937. [DOI: 10.1007/s12035-015-9594-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 12/01/2015] [Indexed: 10/22/2022]
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18
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Hynds DL. Subcellular localization of Rho GTPases: implications for axon regeneration. Neural Regen Res 2015; 10:1032-3. [PMID: 26330813 PMCID: PMC4541221 DOI: 10.4103/1673-5374.160064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2015] [Indexed: 11/20/2022] Open
Affiliation(s)
- DiAnna L Hynds
- Department of Biology, Texas Woman's University, Denton, TX, USA
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19
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Fan X, Hou N, Fan K, Yuan J, Mo X, Deng Y, Wan Y, Teng Y, Yang X, Wu X. Geft is dispensable for the development of the second heart field. BMB Rep 2014; 45:153-8. [PMID: 22449701 DOI: 10.5483/bmbrep.2012.45.3.153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Geft is a guanine nucleotide exchange factor, which can specifically activate Rho family of small GTPase by catalyzing the exchange of bound GDP for GTP. Geft is highly expressed in the excitable tissue as heart and skeletal muscle and plays important roles in many cellular processes, such as cell proliferation, migration, and cell fate decision. However, the in vivo role of Geft remains unknown. Here, we generated a Geft conditional knockout mouse by flanking exons 5-17 of Geft with loxP sites. Cre-mediated deletion of the Geft gene in heart using Mef2c-Cre transgenic mice resulted in a dramatic decrease of Geft expression. Geft knockout mice develop normally and exhibit no discernable phenotype, suggesting Geft is dispensable for the development of the second heart field in mouse. The Geft conditional knockout mouse will be a valuable genetic tool for uncovering the in vivo roles of Geft during development and in adult homeostasis.
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Affiliation(s)
- Xiongwei Fan
- The Center for Heart Development, Key Lab of MOE for Development Biology and Protein Chemistry, College of Life Sciences, Hunan Normal University, Changsha, P.R. China
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20
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Reddy JM, Samuel FG, McConnell JA, Reddy CP, Beck BW, Hynds DL. Non-prenylatable, cytosolic Rac1 alters neurite outgrowth while retaining the ability to be activated. Cell Signal 2014; 27:630-7. [PMID: 25479592 DOI: 10.1016/j.cellsig.2014.11.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 11/26/2014] [Accepted: 11/27/2014] [Indexed: 12/17/2022]
Abstract
Rac1 is an important regulator of axon extension, cell migration and actin reorganization. Like all Rho guanine triphosphatases (GTPases), Rac1 is targeted to the membrane by the addition of a geranylgeranyl moiety, an action thought to result in Rac1 guanosine triphosphate (GTP) binding. However, the role that Rac1 localization plays in its activation (GTP loading) and subsequent activation of effectors is not completely clear. To address this, we developed a non-prenylatable emerald green fluorescent protein (EmGFP)-Rac1 fusion protein (EmGFP-Rac1(C189A)) and assessed how expressing this construct affected neurite outgrowth, Rac1 localization and activation in neuroblastoma cells. Expression of EmGFP-Rac1(C189A) increased localization to the cytosol and induced cell clustering while increasing neurite initiation. EmGFP-Rac1(C189A) expression also increased Rac1 activation in the cytosol, compared to cells expressing wild-type Rac1 (EmGFP-Rac1). These results suggest that activation of Rac1 may not require plasma membrane localization, potentially leading to differential activation of cytosolic signaling pathways that alter cell morphology. Understanding the consequences of differential localization and activation of Rho GTPases, including Rac1, could lead to new therapeutic targets for treating neurological disorders.
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Affiliation(s)
- Jairus M Reddy
- Texas Woman's University Department of Biology, Denton, TX 76204-5799, United States
| | - Filsy G Samuel
- Center for Research in Neurodegenerative Disease, University of Toronto, Toronto, Canada
| | - Jordan A McConnell
- Texas Woman's University Department of Biology, Denton, TX 76204-5799, United States
| | - Cristina P Reddy
- Texas Woman's University Department of Biology, Denton, TX 76204-5799, United States
| | - Brian W Beck
- Texas Woman's University Department of Biology, Denton, TX 76204-5799, United States
| | - DiAnna L Hynds
- Texas Woman's University Department of Biology, Denton, TX 76204-5799, United States.
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21
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Cheng WH, Ho WY, Chang CF, Lu PJ, Cheng PW, Yeh TC, Hong LZ, Sun GC, Hsiao M, Tseng CJ. Simvastatin induces a central hypotensive effect via Ras-mediated signalling to cause eNOS up-regulation. Br J Pharmacol 2014; 170:847-58. [PMID: 23889671 DOI: 10.1111/bph.12317] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 07/08/2013] [Accepted: 07/21/2013] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE Clinical studies indicate that statins have a BP-lowering effect in hypercholesterolemic individuals with hypertension. Specifically, statins modulate BP through the up-regulation of endothelial NOS (eNOS) activation in the brain. However, the signalling mechanisms through which statins enhance eNOS activation remain unclear. Therefore, we examined the possible signalling pathways involved in statin-mediated BP regulation in the nucleus tractus solitarii (NTS). EXPERIMENTAL APPROACH To investigate the involvement of Ras and other signalling pathways in simvastatin-induced effects on BP, BP and renal sympathetic nerve activity (RSNA) were determined in spontaneously hypertensive rats (SHRs) before and after i.c.v. administration of simvastatin in the absence and presence of a Ras-specific inhibitor (farnesyl thiosalicylic acid, FTS), a geranylgeranyltransferase inhibitor (GGTI-2133), a PI3K inhibitor (LY294002) or a MAPK-ERK kinase (MEK) inhibitor (PD98059). KEY RESULTS FTS significantly attenuated the decrease in BP and increased NO evoked by simvastatin and reversed the decrease in basal RSNA induced by simvastatin. Immunoblotting and pharmacological studies showed that inhibition of Ras activity by FTS significantly abolished simvastatin-induced phosphorylation of ERK1/2, ribosomal protein S6 kinase (RSK), Akt and decreased eNOS phosphorylation. Likewise, administration of Akt and ERK1/2 signalling inhibitors, LY294002 and PD98059, attenuated the reduction in BP evoked by simvastatin. Furthermore, i.c.v. simvastatin decreased Rac1 activation and the number of ROS-positive cells in the NTS. CONCLUSIONS AND IMPLICATIONS Simvastatin modulates central BP control in the NTS of SHRs by increasing Ras-mediated activation of the PI3K-Akt and ERK1/2-RSK signalling pathways, which then up-regulates eNOS activation.
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Affiliation(s)
- Wen-Han Cheng
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
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22
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Barszczyk A, Sun HS, Quan Y, Zheng W, Charlton MP, Feng ZP. Differential roles of the mevalonate pathway in the development and survival of mouse Purkinje cells in culture. Mol Neurobiol 2014; 51:1116-29. [PMID: 24973985 DOI: 10.1007/s12035-014-8778-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 06/01/2014] [Indexed: 11/29/2022]
Abstract
The cerebellum is an important locus for motor learning and higher cognitive functions, and Purkinje cells constitute a key component of its circuit. Biochemically, significant turnover of cholesterol occurs in Purkinje cells, causing the activation of the mevalonate pathway. The mevalonate pathway has important roles in cell survival and development. In this study, we investigated the outcomes of mevalonate inhibition in immature and mature mouse cerebellar Purkinje cells in culture. Specifically, we found that the inhibition of the mevalonate pathway by mevastatin resulted in cell death, and geranylgeranylpyrophosphate (GGPP) supplementation significantly enhanced neuronal survival. The surviving immature Purkinje cells, however, exhibited dendritic developmental deficits. The morphology of mature cells was not affected. The inhibition of squalene synthase by zaragozic acid caused impaired dendritic development, similar to that seen in the GGPP-rescued Purkinje cells. Our results indicate GGPP is required for cell survival and squalene synthase for the cell development of Purkinje cells. Abnormalities in Purkinje cells are linked to motor-behavioral learning disorders such as cerebellar ataxia. Thus, serious caution should be taken when using drugs that inhibit geranylgeranylation or the squalene-cholesterol branch of the pathway in the developing stage.
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Affiliation(s)
- Andrew Barszczyk
- Department of Physiology, University of Toronto, Medical Sciences Building, Rm. 3306, 1 King's College, Toronto, ON, M5S 1A8, Canada
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23
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Afshordel S, Wood WG, Igbavboa U, Muller WE, Eckert GP. Impaired geranylgeranyltransferase-I regulation reduces membrane-associated Rho protein levels in aged mouse brain. J Neurochem 2014; 129:732-42. [PMID: 24428713 PMCID: PMC3999261 DOI: 10.1111/jnc.12654] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/09/2014] [Accepted: 01/10/2014] [Indexed: 12/21/2022]
Abstract
Synaptic impairment rather than neuronal loss may be the leading cause of cognitive dysfunction in brain aging. Certain small Rho-GTPases are involved in synaptic plasticity, and their dysfunction is associated with brain aging and neurodegeneration. Rho-GTPases undergo prenylation by attachment of geranylgeranylpyrophosphate (GGPP) catalyzed by GGTase-I. We examined age-related changes in the abundance of Rho and Rab proteins in membrane and cytosolic fractions as well as of GGTase-I in brain tissue of 3- and 23-month-old C57BL/6 mice. We report a shift in the cellular localization of Rho-GTPases toward reduced levels of membrane-associated and enhanced cytosolic levels of those proteins in aged mouse brain as compared with younger mice. The age-related reduction in membrane-associated Rho proteins was associated with a reduction in GGTase-Iβ levels that regulates binding of GGPP to Rho-GTPases. Proteins prenylated by GGTase-II were not reduced in aged brain indicating a specific targeting of GGTase-I in the aged brain. Inhibition of GGTase-I in vitro modeled the effects of aging we observed in vivo. We demonstrate for the first time a decrease in membrane-associated Rho proteins in aged brain in association with down-regulation of GGTase-Iβ. This down-regulation could be one of the mechanisms causing age-related weakening of synaptic plasticity.
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Affiliation(s)
- Sarah Afshordel
- Department of Pharmacology, Biocenter Niederursel, University of Frankfurt, Max-von-Laue-St. 9, 60438 Frankfurt, Germany
| | - W. Gibson Wood
- Department of Pharmacology, University of Minnesota School of Medicine, Geriatric Research, Education and Clinical Center, VAMC, Minneapolis, MN 55417 USA
| | - Urule Igbavboa
- Department of Pharmacology, University of Minnesota School of Medicine, Geriatric Research, Education and Clinical Center, VAMC, Minneapolis, MN 55417 USA
| | - Walter E. Muller
- Department of Pharmacology, Biocenter Niederursel, University of Frankfurt, Max-von-Laue-St. 9, 60438 Frankfurt, Germany
| | - Gunter P. Eckert
- Department of Pharmacology, Biocenter Niederursel, University of Frankfurt, Max-von-Laue-St. 9, 60438 Frankfurt, Germany
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24
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Inhibiting geranylgeranylation increases neurite branching and differentially activates cofilin in cell bodies and growth cones. Mol Neurobiol 2014; 50:49-59. [PMID: 24515839 DOI: 10.1007/s12035-014-8653-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 01/23/2014] [Indexed: 10/25/2022]
Abstract
Inhibitors of the mevalonate pathway, including the highly prescribed statins, reduce the production of cholesterol and isoprenoids such as geranylgeranyl pyrophosphates. The Rho family of small guanine triphosphatases (GTPases) requires isoprenylation, specifically geranylgeranylation, for activation. Because Rho GTPases are primary regulators of actin filament rearrangements required for process extension, neurite arborization, and synaptic plasticity, statins may affect cognition or recovery from nervous system injury. Here, we assessed how manipulating geranylgeranylation affects neurite initiation, elongation, and branching in neuroblastoma growth cones. Treatment with the statin, lovastatin (20 μM), decreased measures of neurite initiation by 17.0 to 19.0 % when a source of cholesterol was present and increased neurite branching by 4.03- to 9.54-fold (regardless of exogenous cholesterol). Neurite elongation was increased by treatment with lovastatin only in cholesterol-free culture conditions. Treatment with lovastatin decreased growth cone actin filament content by up to 24.3 %. In all cases, co-treatment with the prenylation precursor, geranylgeraniol (10 μM), reversed the effect of lovastatin. In a prior work, statin effects on outgrowth were linked to modulating the actin depolymerizing factor, cofilin. In our assays, treatment with lovastatin or geranylgeraniol decreased cofilin phosphorylation in whole cell lysates. However, lovastatin increased cofilin phosphorylation in cell bodies and decreased it in growth cones, indicating differential regulation in specific cell regions. Together, we interpret these data to suggest that protein geranylgeranylation likely regulates growth cone actin filament content and subsequent neurite outgrowth through mechanisms that also affect actin nucleation and polymerization.
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25
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Bolognin S, Lorenzetto E, Diana G, Buffelli M. The potential role of rho GTPases in Alzheimer's disease pathogenesis. Mol Neurobiol 2014; 50:406-22. [PMID: 24452387 DOI: 10.1007/s12035-014-8637-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 01/02/2014] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is characterized by a wide loss of synapses and dendritic spines. Despite extensive efforts, the molecular mechanisms driving this detrimental alteration have not yet been determined. Among the factors potentially mediating this loss of neuronal connectivity, the contribution of Rho GTPases is of particular interest. This family of proteins is classically considered a key regulator of actin cytoskeleton remodeling and dendritic spine maintenance, but new insights into the complex dynamics of its regulation have recently determined how its signaling cascade is still largely unknown, both in physiological and pathological conditions. Here, we review the growing evidence supporting the potential involvement of Rho GTPases in spine loss, which is a unanimously recognized hallmark of early AD pathogenesis. We also discuss some new insights into Rho GTPase signaling framework that might explain several controversial results that have been published. The study of the connection between AD and Rho GTPases represents a quite unchartered avenue that holds therapeutic potential.
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Affiliation(s)
- Silvia Bolognin
- Department of Neurological and Movement Sciences, Section of Physiology, University of Verona, Strada le Grazie 8, 37134, Verona, Italy,
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26
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Sun X, Zhou Z, Fink DJ, Mata M. HspB1 silences translation of PDZ-RhoGEF by enhancing miR-20a and miR-128 expression to promote neurite extension. Mol Cell Neurosci 2013; 57:111-9. [PMID: 24141048 DOI: 10.1016/j.mcn.2013.10.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 10/03/2013] [Accepted: 10/08/2013] [Indexed: 11/17/2022] Open
Abstract
HspB1 is a small heat shock protein implicated in neuronal survival and neurite growth; mutations in HspB1 have been identified in hereditary motor neuronopathies and Charcot Marie Tooth Type 2 neuropathies. In cortical neurons we found that expression of HspB1 decreased RhoA activity and RhoA-GTP protein, and reversed the inhibition of neurite extension induced by NogoA. HspB1 decreased PDZ-RhoGEF, a RhoA specific guanine nucleotide exchange factor, while other regulators of RhoA activity were unchanged. The decrease in PDZ-RhoGEF was independent of proteasomal or lysosomal degradation pathways and was not associated with changes in PDZ-RhoGEF mRNA. We sequenced the 3'UTR of rat PDZ-RhoGEF and found binding sites for miRNAs miR-20a, miR-128 and miR-132. Expression of these microRNAs was substantially increased in cortical neurons transfected with HspB1. Co-transfection of HspB1 with specific inhibitors of miR-20a or miR-128 prevented the decrease in PDZ-RhoGEF and blocked the neurite growth promoting effects of HspB1. Using the 3'UTR of PDZ-RhoGEF mRNA in a luciferase reporter construct we observed that HspB1, miR-20a and miR-128 each inhibited luciferase expression. We conclude that HspB1 regulates RhoA activity through modulation of PDZ-RhoGEF levels achieved by translational control through enhanced expression of specific miRNAs (miR-20a and miR-128). Regulation of RhoA activity by translational silencing of PDZ-RhoGEF may be the mechanism through which HspB1 is involved in regulation of neurite growth. As RhoA-GTPase plays a regulatory role in the organization and stability of cytoskeletal networks through its downstream effectors, the results suggest a possible mechanism linking HspB1 mutations and axonal cytoskeletal pathology.
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Affiliation(s)
- Xiankui Sun
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; GRECC VA Ann Arbor Healthcare System, Ann Arbor, MI 48109, USA
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Lu Y, Liu X, Zhou J, Huang A, Zhou J, He C. TROY interacts with Rho guanine nucleotide dissociation inhibitor α (RhoGDIα) to mediate Nogo-induced inhibition of neurite outgrowth. J Biol Chem 2013; 288:34276-34286. [PMID: 24129566 DOI: 10.1074/jbc.m113.519744] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TROY can functionally substitute p75 to comprise the Nogo receptor complex, which transduces the inhibitory signal of myelin-associated inhibitory factors on axon regeneration following CNS injury. The inhibition of neurite extension relies on TROY-dependent RhoA activation, but how TROY activates RhoA remains unclear. Here, we firstly identified Rho guanine nucleotide dissociation inhibitor α (RhoGDIα) as a binding partner of TROY using GST pull-down combined with two-dimensional gel electrophoresis and mass spectra analysis. The interaction was further confirmed by coimmunoprecipitation in vitro and in vivo. Deletion mutagenesis revealed that two regions of the TROY intracellular domain (amino acids 234-256 and 321-350) were essential for the interaction with RhoGDIα. Secondly, TROY and RhoGDIα were coexpressed in postnatal dorsal root ganglion neurons, cortex neurons, and cerebellar granule neurons (CGNs). Thirdly, TROY/RhoGDIα association was potentiated by Nogo-66 and was independent of p75/RhoGDIα interaction. Fourthly, TROY/RhoGDIα interaction was still able to activate RhoA when p75 was deficient. Furthermore, RhoA activation was decreased dramatically when TROY was knocked down in p75-deficient CGNs cells. Finally, RhoGDIα overexpression abolished RhoA activation and following neurite outgrowth inhibition by Nogo-66 in both wild-type and p75-deficient CGNs. These results showed that the association of RhoGDIα with TROY contributed to TROY-dependent RhoA activation and neurite outgrowth inhibition after Nogo-66 stimulation.
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Affiliation(s)
- Yan Lu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai 200433, China
| | - Xiujie Liu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai 200433, China
| | - Jianfeng Zhou
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai 200433, China
| | - Aijun Huang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai 200433, China
| | - Jiazhen Zhou
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai 200433, China
| | - Cheng He
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai 200433, China.
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Phosphorylation of Rac1 T108 by extracellular signal-regulated kinase in response to epidermal growth factor: a novel mechanism to regulate Rac1 function. Mol Cell Biol 2013; 33:4538-51. [PMID: 24043306 DOI: 10.1128/mcb.00822-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Accumulating evidence has implicated Rho GTPases, including Rac1, in many aspects of cancer development. Recent findings suggest that phosphorylation might further contribute to the tight regulation of Rho GTPases. Interestingly, sequence analysis of Rac1 shows that Rac1 T108 within the (106)PNTP(109) motif is likely an extracellular signal-regulated kinase (ERK) phosphorylation site and that Rac1 also has an ERK docking site, (183)KKRKRKCLLL(192) (D site), at the C terminus. Indeed, we show here that both transfected and endogenous Rac1 interacts with ERK and that this interaction is mediated by its D site. Green fluorescent protein (GFP)-Rac1 is threonine (T) phosphorylated in response to epidermal growth factor (EGF), and EGF-induced Rac1 threonine phosphorylation is dependent on the activation of ERK. Moreover, mutant Rac1 with the mutation of T108 to alanine (A) is not threonine phosphorylated in response to EGF. In vitro ERK kinase assay further shows that pure active ERK phosphorylates purified Rac1 but not mutant Rac1 T108A. We also show that Rac1 T108 phosphorylation decreases Rac1 activity, partially due to inhibiting its interaction with phospholipase C-γ1 (PLC-γ1). T108 phosphorylation targets Rac1 to the nucleus, which isolates Rac1 from other guanine nucleotide exchange factors (GEFs) and hinders Rac1's role in cell migration. We conclude that Rac1 T108 is phosphorylated by ERK in response to EGF, which plays an important role in regulating Rac1.
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Vadodaria KC, Jessberger S. Maturation and integration of adult born hippocampal neurons: signal convergence onto small Rho GTPases. Front Synaptic Neurosci 2013; 5:4. [PMID: 23986696 PMCID: PMC3752586 DOI: 10.3389/fnsyn.2013.00004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/29/2013] [Indexed: 01/28/2023] Open
Abstract
Adult neurogenesis, restricted to specific regions in the mammalian brain, represents one of the most interesting forms of plasticity in the mature nervous system. Adult-born hippocampal neurons play important roles in certain forms of learning and memory, and altered hippocampal neurogenesis has been associated with a number of neuropsychiatric diseases such as major depression and epilepsy. Newborn neurons go through distinct developmental steps, from a dividing neurogenic precursor to a synaptically integrated mature neuron. Previous studies have uncovered several molecular signaling pathways involved in distinct steps of this maturational process. In this context, the small Rho GTPases, Cdc42, Rac1, and RhoA have recently been shown to regulate the morphological and synaptic maturation of adult-born dentate granule cells in vivo. Distinct upstream regulators, including growth factors that modulate maturation and integration of newborn neurons have been shown to also recruit the small Rho GTPases. Here we review recent findings and highlight the possibility that small Rho GTPases may act as central assimilators, downstream of critical input onto adult-born hippocampal neurons contributing to their maturation and integration into the existing dentate gyrus (DG) circuitry.
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Affiliation(s)
- Krishna C Vadodaria
- Brain Research Institute, University of Zurich Zurich, Switzerland ; Neuroscience Center Zurich, University of Zurich and ETH Zurich Zurich, Switzerland
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FilGAP and its close relatives: a mediator of Rho-Rac antagonism that regulates cell morphology and migration. Biochem J 2013; 453:17-25. [PMID: 23763313 DOI: 10.1042/bj20130290] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Cell migration, phagocytosis and cytokinesis are mechanically intensive cellular processes that are mediated by the dynamic assembly and contractility of the actin cytoskeleton. GAPs (GTPase-activating proteins) control activities of the Rho family proteins including Cdc42, Rac1 and RhoA, which are prominent upstream regulators of the actin cytoskeleton. The present review concerns a class of Rho GAPs, FilGAP (ARHGAP24 gene product) and its close relatives (ARHGAP22 and AHRGAP25 gene products). FilGAP is a GAP for Rac1 and a binding partner of FLNa (filamin A), a widely expressed F-actin (filamentous actin)-cross-linking protein that binds many different proteins that are important in cell regulation. Phosphorylation of FilGAP serine/threonine residues and binding to FLNa modulate FilGAP's GAP activity and, as a result, its ability to regulate cell protrusion and spreading. FLNa binds to FilGAP at F-actin-enriched sites, such as at the leading edge of the cell where Rac1 activity is controlled to inhibit actin assembly. FilGAP then dissociates from FLNa in actin networks by myosin-dependent mechanical deformation of FLNa's FilGAP-binding site to relocate at the plasma membrane by binding to polyphosphoinositides. Since actomyosin contraction is activated downstream of RhoA-ROCK (Rho-kinase), RhoA activity regulates Rac1 through FilGAP by signalling to the force-generating system. FilGAP and the ARHGAP22 gene product also act as mediators between RhoA and Rac1 pathways, which lead to amoeboid and mesenchymal modes of cell movements respectively. Therefore FilGAP and its close relatives are key regulators that promote the reciprocal inhibitory relationship between RhoA and Rac1 in cell shape changes and the mesenchymal-amoeboid transition in tumour cells.
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Sabirzhanova I, Liu C, Zhao J, Bramlett H, Dietrich WD, Hu B. Changes in the GEF-H1 pathways after traumatic brain injury. J Neurotrauma 2013; 30:1449-56. [PMID: 23611588 DOI: 10.1089/neu.2012.2673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Brains undergo significant remodeling after traumatic brain injury (TBI). The Rho guanine triphosphate (GTP)ase pathways control brain remodeling during development and under pathological conditions. How the Rho GTPase pathways are regulated in the brain after TBI remains largely unknown, however. This study used the rat fluid percussion injury model to investigate changes in the Rho GTPase pathways after TBI. The results showed that TBI leads to activation and translocation of RhoA and Rac1 proteins from cytosolic fraction to the membrane fraction after injury. Consistently, the Rho guanine nucleotide exchange factors GEF-H1 and Cool-2/αPix are significantly activated by dephosphorylation and accumulation in the cytosolic fractions during the post-TBI phase. Because the Rho GTPase pathways are key regulators of brain remodeling, these results depict regulatory mechanisms of the Rho GTPase pathways after TBI, and pave the way for the study of therapeutic agents targeting the Rho GTPase pathways for functional recovery after TBI.
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Affiliation(s)
- Inna Sabirzhanova
- Neurochemistry Laboratory of Brain Injury, Department of Anesthesiology, and Shock Trauma and Anesthesiology Research Center, University of Maryland School of Medicine , Baltimore, MD 21201, USA
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Posada-Duque RA, Velasquez-Carvajal D, Eckert GP, Cardona-Gomez GP. Atorvastatin requires geranylgeranyl transferase-I and Rac1 activation to exert neuronal protection and induce plasticity. Neurochem Int 2013; 62:433-45. [PMID: 23411415 DOI: 10.1016/j.neuint.2013.01.026] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 01/23/2013] [Accepted: 01/26/2013] [Indexed: 11/24/2022]
Abstract
Statins are widely used cholesterol-lowering drugs that may reduce the incidence of stroke and the progression of Alzheimer's disease (AD). However, how statins exert these beneficial effects remains poorly understood. Thus, this study evaluated the roles of Rac1 geranylgeranylation and the relationship between Rac1 and αN-catenin in the protective activity of atorvastatin (ATV) in a cortical neuronal culture model of glutamate (GLU) excitotoxicity. We found that ATV-induced neuroprotection and plasticity were blocked by isoprenoids, such as farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP), inhibition of farnesylation (FTI-277) and geranylgeranylation (GGTI-286), down-regulation of GGTase-Iβ and Rac activity and promotion of active RhoA. Additionally, ATV rescued the distribution of dendritic αN-catenin and increased the number and length of dendritic branches; these effects were reversed by GGTI-286, GGTase-Iβ shRNA, Rac1 shRNA and a dominant-negative version of Rac1 (T17N). In summary, our findings suggest that ATV requires GGTase-Iβ, prenylation and active Rac1 to induce protection and plasticity. In this regard, αN-catenin is a marker for stable interactions between adhesion proteins and the actin cytoskeleton and is necessary for the neuroprotective action of ATV.
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Affiliation(s)
- Rafael Andrés Posada-Duque
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, Faculty of Medicine, SIU, University of Antioquia, Medellín, Colombia
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Forgione N, Fehlings MG. Rho-ROCK inhibition in the treatment of spinal cord injury. World Neurosurg 2013; 82:e535-9. [PMID: 23298675 DOI: 10.1016/j.wneu.2013.01.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 01/03/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND The Rho pathway has been shown to have a role in the pathophysiology of spinal cord injury (SCI). Upregulation of the Rho signaling pathway occurs as a result of SCI. Activation of Rho and its downstream effector kinases triggers growth cone collapse and represents a significant barrier to axon regeneration. Furthermore, there is evidence that Rho-ROCK signaling mediates the inhibitory effects of chondroitin sulfate proteoglycans on neurons, and that inhibition of Rho and ROCK can reverse chondroitin sulfate proteoglycan-mediated inhibition of neurite outgrowth. Work building on these findings suggests that inhibition of this pathway may boost neuroprotection and axonal regeneration after SCI. METHODS A narrative review. RESULTS Investigators have identified a C3 transferase, which selectively inhibits Rho without affecting other guanine triphosphatases. This has been shown to promote axonal sprouting and recovery of locomotor function after hemisection of the thoracic spinal cord in a mouse model of SCI. The neuroprotective properties of Rho inhibitors in animal models of SCI have been reinforced by studies carried out in vitro using retinal ganglion cells. In light of this, a Rho inhibitor known as Cethrin has been evaluated as a therapeutic intervention for SCI in a phase I/IIa clinical trial with promising results. CONCLUSIONS The Rho pathway has been shown to have a role in the pathophysiology of SCI and preclinical and clinical work and is currently a promising target for the treatment of patients with SCI.
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Affiliation(s)
- Nicole Forgione
- Division of Genetics and Development, Toronto Western Research Institute, Toronto, Ontario, Canada
| | - Michael G Fehlings
- Division of Neurosurgery, University of Toronto, Toronto, Ontario, Canada.
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Palazzolo G, Horvath P, Zenobi-Wong M. The flavonoid isoquercitrin promotes neurite elongation by reducing RhoA activity. PLoS One 2012; 7:e49979. [PMID: 23209630 PMCID: PMC3510166 DOI: 10.1371/journal.pone.0049979] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 10/18/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Neurite formation and synaptic patterning are fundamental to the development of a functional nervous system. Flavonoids are natural molecules known for having beneficial effects on brain health through diverse molecular pathways. Cytoskeletal changes occurring during neuritogenesis and synapse formation often involve Rho GTPases. Here we hypothesized that the flavonoid isoquercitrin promotes neuronal differentiation through Rho signalling. METHODOLOGY/PRINCIPAL FINDINGS We performed time lapse imaging of NG108-15 cells during incubation with/without isoquercitrin. Isoquercitrin stimulated extensive neurites enriched in the synaptic vesicle protein synaptotagmin-1. Neurite extension was augmented by the ROCK inhibitor Y-27632 suggesting an inactivation of RhoA/Rho kinase as the mechanism. To test this, we first measured the dose-dependent effect of isoquercitrin on RhoA activity and found a 47% reduction in RhoA activity at concentrations which induced neurites (≥40 µM). Secondly, we tested the ability of isoquercitrin to rescue the neural phenotype in a model of RhoA-induced neurite retraction and found that 40 µM isoquercitrin added to cultures previously treated with the RhoA activator calpeptin produced significantly more neurite length/cell than calpeptin alone. Finally, we tested the hypothesis that isoquercitrin may affect RhoA localization preventing the translocation to the plasma membrane. Unexpectedly, immunolocalization studies showed that RhoA was present in nuclear compartments of control NG108-cells, but underwent translocation to the cytoplasm upon treatment with isoquercitrin. DNA microarrays and reverse transcription - quantitative PCR (RT-qPCR) revealed differences in global gene expression of Rho GTPase family members. These data taken together indicate that isoquercitrin is a potential stimulator of neuronal differentiation, through multiple Rho GTPase mediated mechanisms. CONCLUSIONS/SIGNIFICANCE As several members of the Rho GTPase family are implicated in human neurological disorders/injuries, our results suggest that isoquercitrin could be used in the treatment of these pathological states through its effect on this family of molecular switches.
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Affiliation(s)
- Gemma Palazzolo
- Cartilage Engineering+Regeneration Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Peter Horvath
- Light Microscopy and Screening Centre, ETH Zurich, Zurich, Switzerland
| | - Marcy Zenobi-Wong
- Cartilage Engineering+Regeneration Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
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Cook M, Mani P, Wentzell JS, Kretzschmar D. Increased RhoA prenylation in the loechrig (loe) mutant leads to progressive neurodegeneration. PLoS One 2012; 7:e44440. [PMID: 22970217 PMCID: PMC3435293 DOI: 10.1371/journal.pone.0044440] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 08/03/2012] [Indexed: 01/08/2023] Open
Abstract
The Drosophila mutant loechrig (loe) shows age-dependent degeneration of the nervous system and is caused by the loss of a neuronal isoform of the AMP-activated protein kinase (AMPK) γ-subunit (also known as SNF4Aγ). The trimeric AMPK complex is activated by low energy levels and metabolic insults and regulates multiple important signal pathways that control cell metabolism. A well-known downstream target of AMPK is hydroxyl-methylglutaryl-CoA reductase (HMGR), a key enzyme in isoprenoid synthesis, and we have previously shown that HMGR genetically interacts with loe and affects the severity of the degenerative phenotype. Prenylation of proteins like small G-proteins is an important posttranslational modification providing lipid moieties that allow the association of these proteins with membranes, thereby facilitating their subsequent activation. Rho proteins have been extensively studied in neuronal outgrowth, however, much less is known about their function in neuronal maintenance. Here we show that the loe mutation interferes with isoprenoid synthesis, leading to increased prenylation of the small GTPase Rho1, the fly orthologue of vertebrate RhoA. We also demonstrate that increased prenylation and Rho1 activity causes neurodegeneration and aggravates the behavioral and degenerative phenotypes of loe. Because we cannot detect defects in the development of the central nervous system in loe, this suggests that loe only interferes with the function of the RhoA pathway in maintaining neuronal integrity during adulthood. In addition, our results show that alterations in isoprenoids can result in progressive neurodegeneration, supporting findings in vertebrates that prenylation may play a role in neurodegenerative diseases like Alzheimer’s Disease.
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Affiliation(s)
- Mandy Cook
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Sciences University, Portland, Oregon, United States of America
| | - Priya Mani
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Sciences University, Portland, Oregon, United States of America
| | - Jill S. Wentzell
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Sciences University, Portland, Oregon, United States of America
| | - Doris Kretzschmar
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Sciences University, Portland, Oregon, United States of America
- * E-mail:
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Kraft R, Kahn A, Medina-Franco JL, Orlowski ML, Baynes C, López-Vallejo F, Barnard K, Maggiora GM, Restifo LL. A cell-based fascin bioassay identifies compounds with potential anti-metastasis or cognition-enhancing functions. Dis Model Mech 2012; 6:217-35. [PMID: 22917928 PMCID: PMC3529353 DOI: 10.1242/dmm.008243] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The actin-bundling protein fascin is a key mediator of tumor invasion and metastasis and its activity drives filopodia formation, cell-shape changes and cell migration. Small-molecule inhibitors of fascin block tumor metastasis in animal models. Conversely, fascin deficiency might underlie the pathogenesis of some developmental brain disorders. To identify fascin-pathway modulators we devised a cell-based assay for fascin function and used it in a bidirectional drug screen. The screen utilized cultured fascin-deficient mutant Drosophila neurons, whose neurite arbors manifest the 'filagree' phenotype. Taking a repurposing approach, we screened a library of 1040 known compounds, many of them FDA-approved drugs, for filagree modifiers. Based on scaffold distribution, molecular-fingerprint similarities, and chemical-space distribution, this library has high structural diversity, supporting its utility as a screening tool. We identified 34 fascin-pathway blockers (with potential anti-metastasis activity) and 48 fascin-pathway enhancers (with potential cognitive-enhancer activity). The structural diversity of the active compounds suggests multiple molecular targets. Comparisons of active and inactive compounds provided preliminary structure-activity relationship information. The screen also revealed diverse neurotoxic effects of other drugs, notably the 'beads-on-a-string' defect, which is induced solely by statins. Statin-induced neurotoxicity is enhanced by fascin deficiency. In summary, we provide evidence that primary neuron culture using a genetic model organism can be valuable for early-stage drug discovery and developmental neurotoxicity testing. Furthermore, we propose that, given an appropriate assay for target-pathway function, bidirectional screening for brain-development disorders and invasive cancers represents an efficient, multipurpose strategy for drug discovery.
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Affiliation(s)
- Robert Kraft
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA
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Gonzalez-Billault C, Muñoz-Llancao P, Henriquez DR, Wojnacki J, Conde C, Caceres A. The role of small GTPases in neuronal morphogenesis and polarity. Cytoskeleton (Hoboken) 2012; 69:464-85. [PMID: 22605667 DOI: 10.1002/cm.21034] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 04/12/2012] [Accepted: 04/16/2012] [Indexed: 12/21/2022]
Abstract
The highly dynamic remodeling and cross talk of the microtubule and actin cytoskeleton support neuronal morphogenesis. Small RhoGTPases family members have emerged as crucial regulators of cytoskeletal dynamics. In this review we will comprehensively analyze findings that support the participation of RhoA, Rac, Cdc42, and TC10 in different neuronal morphogenetic events ranging from migration to synaptic plasticity. We will specifically address the contribution of these GTPases to support neuronal polarity and axonal elongation.
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Affiliation(s)
- Christian Gonzalez-Billault
- Faculty of Sciences, Laboratory of Cell and Neuronal Dynamics, Department of Biology and Institute for Cell Dynamics and Biotechnology, Universidad de Chile, Santiago, Chile.
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Abstract
Members of the Rab or ARF/Sar branches of the Ras GTPase superfamily regulate almost every step of intracellular membrane traffic. A rapidly growing body of evidence indicates that these GTPases do not act as lone agents but are networked to one another through a variety of mechanisms to coordinate the individual events of one stage of transport and to link together the different stages of an entire transport pathway. These mechanisms include guanine nucleotide exchange factor (GEF) cascades, GTPase-activating protein (GAP) cascades, effectors that bind to multiple GTPases, and positive-feedback loops generated by exchange factor-effector interactions. Together these mechanisms can lead to an ordered series of transitions from one GTPase to the next. As each GTPase recruits a unique set of effectors, these transitions help to define changes in the functionality of the membrane compartments with which they are associated.
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Affiliation(s)
- Emi Mizuno-Yamasaki
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan.
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Perez SE, Getova DP, He B, Counts SE, Geula C, Desire L, Coutadeur S, Peillon H, Ginsberg SD, Mufson EJ. Rac1b increases with progressive tau pathology within cholinergic nucleus basalis neurons in Alzheimer's disease. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:526-40. [PMID: 22142809 PMCID: PMC3349868 DOI: 10.1016/j.ajpath.2011.10.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 10/05/2011] [Accepted: 10/11/2011] [Indexed: 01/19/2023]
Abstract
Cholinergic basal forebrain (CBF) nucleus basalis (NB) neurons display neurofibrillary tangles (NFTs) during Alzheimer's disease (AD) progression, yet the mechanisms underlying this selective vulnerability are currently unclear. Rac1, a member of the Rho family of GTPases, may interact with the proapoptotic pan-neurotrophin receptor p75(NTR) to induce neuronal cytoskeletal abnormalities in AD NB neurons. Herein, we examined the expression of Rac1b, a constitutively active splice variant of Rac1, in NB cholinergic neurons during AD progression. CBF tissues harvested from people who died with a clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment, or AD were immunolabeled for both p75(NTR) and Rac1b. Rac1b appeared as cytoplasmic diffuse granules, loosely aggregated filaments, or compact spheres in p75(NTR)-positive NB neurons. Although Rac1b colocalized with tau cytoskeletal markers, the percentage of p75(NTR)-immunoreactive neurons expressing Rac1b was significantly increased only in AD compared with both mild cognitive impairment and NCI. Furthermore, single-cell gene expression profiling with custom-designed microarrays showed down-regulation of caveolin 2, GNB4, and lipase A in AD Rac1b-positive/p75(NTR)-labeled NB neurons compared with Rac1b-negative/p75(NTR)-positive perikarya in NCI. These proteins are involved in Rac1 pathway/cell cycle progression and lipid metabolism. These data suggest that Rac1b expression acts as a modulator or transducer of various signaling pathways that lead to NFT formation and membrane dysfunction in a subgroup of CBF NB neurons in AD.
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Affiliation(s)
- Sylvia E. Perez
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois
| | - Damianka P. Getova
- Department of Pharmacology and Clinical Pharmacology, Medical University, Plovdiv, Bulgaria
| | - Bin He
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois
| | - Scott E. Counts
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois
| | - Changiz Geula
- Cognitive Neurology and Alzheimer's Disease Center, Northwestern University, Chicago Illinois
| | | | | | | | - Stephen D. Ginsberg
- Center for Dementia Research and Departments of Psychiatry and Physiology and Neuroscience, Nathan Kline Institute/New York University Langone Medical Center, New York, New York
| | - Elliott J. Mufson
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois
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Mocholí E, Ballester-Lurbe B, Arqué G, Poch E, Peris B, Guerri C, Dierssen M, Guasch RM, Terrado J, Pérez-Roger I. RhoE deficiency produces postnatal lethality, profound motor deficits and neurodevelopmental delay in mice. PLoS One 2011; 6:e19236. [PMID: 21552537 PMCID: PMC3084285 DOI: 10.1371/journal.pone.0019236] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Accepted: 03/30/2011] [Indexed: 01/02/2023] Open
Abstract
Rnd proteins are a subfamily of Rho GTPases involved in the control of actin cytoskeleton dynamics and other cell functions such as motility, proliferation and survival. Unlike other members of the Rho family, Rnd proteins lack GTPase activity and therefore remain constitutively active. We have recently described that RhoE/Rnd3 is expressed in the Central Nervous System and that it has a role in promoting neurite formation. Despite their possible relevance during development, the role of Rnd proteins in vivo is not known. To get insight into the in vivo function of RhoE we have generated mice lacking RhoE expression by an exon trapping cassette. RhoE null mice (RhoE gt/gt) are smaller at birth, display growth retardation and early postnatal death since only half of RhoE gt/gt mice survive beyond postnatal day (PD) 15 and 100% are dead by PD 29. RhoE gt/gt mice show an abnormal body position with profound motor impairment and impaired performance in most neurobehavioral tests. Null mutant mice are hypoactive, show an immature locomotor pattern and display a significant delay in the appearance of the hindlimb mature responses. Moreover, they perform worse than the control littermates in the wire suspension, vertical climbing and clinging, righting reflex and negative geotaxis tests. Also, RhoE ablation results in a delay of neuromuscular maturation and in a reduction in the number of spinal motor neurons. Finally, RhoE gt/gt mice lack the common peroneal nerve and, consequently, show a complete atrophy of the target muscles. This is the first model to study the in vivo functions of a member of the Rnd subfamily of proteins, revealing the important role of Rnd3/RhoE in the normal development and suggesting the possible involvement of this protein in neurological disorders.
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Affiliation(s)
- Enric Mocholí
- Department of Chemistry, Biochemistry and Molecular Biology, School of Health Sciences, Universidad CEU Cardenal Herrera, Moncada, Valencia, Spain
| | - Begoña Ballester-Lurbe
- Department of Animal Medicine and Surgery, School of Veterinary Sciences, Universidad CEU Cardenal Herrera, Moncada, Valencia, Spain
| | - Gloria Arqué
- Genes and Disease Program, Center for Genomic Regulation (CRG), Barcelona Biomedical Research Park (PRBB) and CIBER de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Enric Poch
- Department of Chemistry, Biochemistry and Molecular Biology, School of Health Sciences, Universidad CEU Cardenal Herrera, Moncada, Valencia, Spain
| | - Blanca Peris
- Laboratory of Cellular Pathology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Consuelo Guerri
- Laboratory of Cellular Pathology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - Mara Dierssen
- Genes and Disease Program, Center for Genomic Regulation (CRG), Barcelona Biomedical Research Park (PRBB) and CIBER de Enfermedades Raras (CIBERER), Barcelona, Spain
| | - Rosa M. Guasch
- Laboratory of Cellular Pathology, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | - José Terrado
- Department of Animal Medicine and Surgery, School of Veterinary Sciences, Universidad CEU Cardenal Herrera, Moncada, Valencia, Spain
- * E-mail: (IP-R); (JT)
| | - Ignacio Pérez-Roger
- Department of Chemistry, Biochemistry and Molecular Biology, School of Health Sciences, Universidad CEU Cardenal Herrera, Moncada, Valencia, Spain
- * E-mail: (IP-R); (JT)
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Global Identification of Protein Prenyltransferase Substrates. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/b978-0-12-381339-8.00012-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023]
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