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van der Horst J, Rognant S, Hellsten Y, Aalkjær C, Jepps TA. Dynein Coordinates β2-Adrenoceptor-Mediated Relaxation in Normotensive and Hypertensive Rat Mesenteric Arteries. Hypertension 2022; 79:2214-2227. [PMID: 35929419 DOI: 10.1161/hypertensionaha.122.19351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The voltage-gated potassium channel (Kv)7.4 and Kv7.5 channels contribute to the β-adrenoceptor-mediated vasodilatation. In arteries from hypertensive rodents, the Kv7.4 channel is downregulated and function attenuated, which contributes to the reduced β-adrenoceptor-mediated vasodilatation observed in these arteries. Recently, we showed that disruption of the microtubule network, with colchicine, or inhibition of the microtubule motor protein, dynein, with ciliobrevin D, enhanced the membrane abundance and function of Kv7.4 channels in rat mesenteric arteries. This study aimed to determine whether these pharmacological compounds can improve Kv7.4 function in third-order mesenteric arteries from the spontaneously hypertensive rat, thereby restoring the β-adrenoceptor-mediated vasodilatation. METHODS Wire and intravital myography was performed on normotensive and hypertensive male rat mesenteric arteries and immunostaining was performed on isolated smooth muscle cells from the same arteries. RESULTS Using wire and intravital microscopy, we show that ciliobrevin D enhanced the β-adrenoceptor-mediated vasodilatation by isoprenaline. This effect was inhibited partially by the Kv7 channel blocker linopirdine and was dependent on an increased functional contribution of the β2-adrenoceptor to the isoprenaline-mediated relaxation. In mesenteric arteries from the spontaneously hypertensive rat, ciliobrevin D and colchicine both improved the isoprenaline-mediated vasorelaxation and relaxation to the Kv7.2 -7.5 activator, ML213. Immunostaining confirmed ciliobrevin D enhanced the membrane abundance of Kv7.4. As well as an increase in the function of Kv7.4, the functional changes were associated with an increase in the contribution of β2-adrenoceptor following isoprenaline treatment. Immunostaining experiments showed ciliobrevin D prevented isoprenaline-mediated internalizationof the β2-adrenoceptor. CONCLUSIONS Overall, these data show that colchicine and ciliobrevin D can induce a β2-adrenoceptor-mediated vasodilatation in arteries from the spontaneously hypertensive rat as well as reinstating Kv7.4 channel function.
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Affiliation(s)
- Jennifer van der Horst
- Department of Biomedical Sciences (J.v.d.H., S.R., C.A., T.A.J.), University of Copenhagen, Denmark.,The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports (J.v.d.H., Y.H.), University of Copenhagen, Denmark
| | - Salomé Rognant
- Department of Biomedical Sciences (J.v.d.H., S.R., C.A., T.A.J.), University of Copenhagen, Denmark
| | - Ylva Hellsten
- The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports (J.v.d.H., Y.H.), University of Copenhagen, Denmark
| | - Christian Aalkjær
- Department of Biomedical Sciences (J.v.d.H., S.R., C.A., T.A.J.), University of Copenhagen, Denmark.,Department of Biomedicine, Aarhus University, Denmark (C.A.)
| | - Thomas A Jepps
- Department of Biomedical Sciences (J.v.d.H., S.R., C.A., T.A.J.), University of Copenhagen, Denmark
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Jepps TA. Kv7 channel trafficking by the microtubule network in vascular smooth muscle. Acta Physiol (Oxf) 2021; 232:e13692. [PMID: 34021973 PMCID: PMC8365713 DOI: 10.1111/apha.13692] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/17/2021] [Accepted: 05/19/2021] [Indexed: 12/17/2022]
Abstract
In arterial smooth muscle cells, changes in availability of integral membrane proteins influence the regulation of blood flow and blood pressure, which is critical for human health. However, the mechanisms that coordinate the trafficking and membrane expression of specific receptors and ion channels in vascular smooth muscle are poorly understood. In the vasculature, very little is known about microtubules, which form a road network upon which proteins can be transported to and from the cell membrane. This review article summarizes the impact of the microtubule network on arterial contractility, highlighting the importance of the network, with an emphasis on our recent findings regarding the trafficking of the voltage‐dependent Kv7 channels.
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Affiliation(s)
- Thomas A Jepps
- Vascular Biology Group Department of Biomedical Sciences University of Copenhagen Blegdamsvej 3 2200 Copenhagen N Denmark
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3
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EB2 promotes hepatocellular carcinoma proliferation and metastasis via MAPK/ERK pathway by modulating microtubule dynamics. Clin Sci (Lond) 2021; 135:847-864. [PMID: 33755094 DOI: 10.1042/cs20201500] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/09/2021] [Accepted: 03/23/2021] [Indexed: 01/22/2023]
Abstract
Metastasis is the main cause of poor postoperative survival of hepatocellular carcinoma (HCC) patients. Cytoskeleton rearrangement is a key event in cancer metastasis. However, the significance of microtubule (MT), one of the core components of cytoskeleton, in this process is only beginning to be revealed. Here, we find that the MT dynamics regulator end-binding protein 2 (EB2) is highly expressed in HCC and predicts poor prognosis of HCC patients. Functional studies show that EB2 overexpression promotes HCC proliferation, invasion and metastasis in vitro and in vivo, while EB2 knockdown has opposite results. Mechanistically, EB2 mediates MTs destabilization, increases Src (Src proto-oncogene non-receptor tyrosine kinase) activity, and thus facilitates extracellular signal-regulated kinase (ERK) signaling activation, which could in turn promote EB2 expression in HCC, eventually resulting in enhanced HCC proliferation, invasion and metastasis. Furthermore, U0126, a specific ERK inhibitor, could effectively inhibit EB2-mediated HCC proliferation and metastasis in vitro and in vivo. In conclusion, EB2 coordinates MT cytoskeleton and intracellular signal transduction, forming an EB2-MT-ERK positive feedback loop, to facilitate HCC proliferation, invasion and metastasis. EB2 could serve as a promising prognostic biomarker and potential therapeutic target for HCC; HCC patients with high EB2 expression may benefit from treatment with ERK inhibitors.
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4
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Joo E, Olson MF. Regulation and functions of the RhoA regulatory guanine nucleotide exchange factor GEF-H1. Small GTPases 2020; 12:358-371. [PMID: 33126816 PMCID: PMC8583009 DOI: 10.1080/21541248.2020.1840889] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Since the discovery by Madaule and Axel in 1985 of the first Ras homologue (Rho) protein in Aplysia and its human orthologue RhoB, membership in the Rho GTPase family has grown to 20 proteins, with representatives in all eukaryotic species. These GTPases are molecular switches that cycle between active (GTP bound) and inactivate (GDP bound) states. The exchange of GDP for GTP on Rho GTPases is facilitated by guanine exchange factors (GEFs). Approximately 80 Rho GEFs have been identified to date, and only a few GEFs associate with microtubules. The guanine nucleotide exchange factor H1, GEF-H1, is a unique GEF that associates with microtubules and is regulated by the polymerization state of microtubule networks. This review summarizes the regulation and functions of GEF-H1 and discusses the roles of GEF-H1 in human diseases.
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Affiliation(s)
- Emily Joo
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Michael F Olson
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
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5
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Niftullayev S, Lamarche-Vane N. Regulators of Rho GTPases in the Nervous System: Molecular Implication in Axon Guidance and Neurological Disorders. Int J Mol Sci 2019; 20:E1497. [PMID: 30934641 PMCID: PMC6471118 DOI: 10.3390/ijms20061497] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 03/18/2019] [Indexed: 12/11/2022] Open
Abstract
One of the fundamental steps during development of the nervous system is the formation of proper connections between neurons and their target cells-a process called neural wiring, failure of which causes neurological disorders ranging from autism to Down's syndrome. Axons navigate through the complex environment of a developing embryo toward their targets, which can be far away from their cell bodies. Successful implementation of neuronal wiring, which is crucial for fulfillment of all behavioral functions, is achieved through an intimate interplay between axon guidance and neural activity. In this review, our focus will be on axon pathfinding and the implication of some of its downstream molecular components in neurological disorders. More precisely, we will talk about axon guidance and the molecules implicated in this process. After, we will briefly review the Rho family of small GTPases, their regulators, and their involvement in downstream signaling pathways of the axon guidance cues/receptor complexes. We will then proceed to the final and main part of this review, where we will thoroughly comment on the implication of the regulators for Rho GTPases-GEFs (Guanine nucleotide Exchange Factors) and GAPs (GTPase-activating Proteins)-in neurological diseases and disorders.
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Affiliation(s)
- Sadig Niftullayev
- Cancer Research Program, Research Institute of the MUHC, Montreal, QC H4A 3J1, Canada.
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 2B2, Canada.
| | - Nathalie Lamarche-Vane
- Cancer Research Program, Research Institute of the MUHC, Montreal, QC H4A 3J1, Canada.
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 2B2, Canada.
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6
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Di Pardo A, Castaldo S, Amico E, Pepe G, Marracino F, Capocci L, Giovannelli A, Madonna M, van Bergeijk J, Buttari F, van der Kam E, Maglione V. Stimulation of S1PR5 with A-971432, a selective agonist, preserves blood-brain barrier integrity and exerts therapeutic effect in an animal model of Huntington's disease. Hum Mol Genet 2019; 27:2490-2501. [PMID: 29688337 DOI: 10.1093/hmg/ddy153] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 04/19/2018] [Indexed: 12/21/2022] Open
Abstract
Huntington's disease (HD) is the most common neurodegenerative disorder for which no effective cure is yet available. Although several agents have been identified to provide benefits so far, the number of therapeutic options remains limited with only symptomatic treatment available. Over the past few years, we have demonstrated that sphingolipid-based approaches may open the door to new and more targeted treatments for the disease. In this study, we investigated the therapeutic potential of stimulating sphingosine-1-phosphate (S1P) receptor 5 by the new selective agonist A-971432 (provided by AbbVie) in R6/2 mice, a widely used HD animal model. Chronic administration of low-dose (0.1 mg/kg) A-971432 slowed down the progression of the disease and significantly prolonged lifespan in symptomatic R6/2 mice. Such beneficial effects were associated with activation of pro-survival pathways (BDNF, AKT and ERK) and with reduction of mutant huntingtin aggregation. A-971432 also protected blood-brain barrier (BBB) homeostasis in the same mice. Interestingly, when administered early in the disease, before any overt symptoms, A-971432 completely protected HD mice from the classic progressive motor deficit and preserved BBB integrity. Beside representing a promising strategy to take into consideration for the development of alternative therapeutic options for HD, selective stimulation of S1P receptor 5 may be also seen as an effective approach to target brain vasculature defects in the disease.
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Affiliation(s)
- Alba Di Pardo
- IRCCS Neuromed, Localitá Camerelle, Pozzilli (IS), Italy
| | | | - Enrico Amico
- IRCCS Neuromed, Localitá Camerelle, Pozzilli (IS), Italy
| | - Giuseppe Pepe
- IRCCS Neuromed, Localitá Camerelle, Pozzilli (IS), Italy
| | | | - Luca Capocci
- IRCCS Neuromed, Localitá Camerelle, Pozzilli (IS), Italy
| | | | | | | | - Fabio Buttari
- IRCCS Neuromed, Localitá Camerelle, Pozzilli (IS), Italy
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Activation of NPY-Y2 receptors ameliorates disease pathology in the R6/2 mouse and PC12 cell models of Huntington's disease. Exp Neurol 2018; 302:112-128. [DOI: 10.1016/j.expneurol.2018.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/27/2017] [Accepted: 01/02/2018] [Indexed: 12/11/2022]
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8
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Ren Y, Wang X, Lou Z, Huang S, Zhuang H, Wang Y, Weng G, Wang P. Induction of cell cycle arrest by increasing GTP‑RhoA levels via Taxol‑induced microtubule polymerization in renal cell carcinoma. Mol Med Rep 2017; 15:4273-4279. [PMID: 28487984 PMCID: PMC5436224 DOI: 10.3892/mmr.2017.6543] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 01/20/2017] [Indexed: 12/12/2022] Open
Abstract
Renal cell carcinoma (RCC) is the most common neoplasm of the kidney in adults, accounting for ~3% of adult malignancies. Understanding the underlying mechanism of RCC tumorigenesis is necessary to improve patient survival. The present study revealed that Taxol-induced microtubule (MT) polymerization causes cell cycle arrest and an increase in guanosine triphosphate-Ras homology gene family, member A (GTP-RhoA) protein expression. Disruption of Taxol-induced MT polymerization reversed GTP-RhoA expression and cell cycle arrest. The localization and redistribution of MTs and RhoA were consistent in cells with MT bundles and those without. Decreased GTP-RhoA had no marked effect on Taxol-induced MT bundling, however, it reduced the proportion of cells in G2/M phase. Taken together, Taxol-induced MT polymerization regulated the protein expression levels of GTP-RhoA and cell cycle arrest. However, the alteration in GTP-RhoA expression did not influence MT arrangement, suggesting that GTP-RhoA serves a pivotal role in Taxol-induced MT polymerization and cell cycle arrest in RCC.
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Affiliation(s)
- Yu Ren
- Department of Urologic Surgery, Ningbo Urology and Nephrology Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Xue Wang
- Department of Urologic Surgery, Ningbo Urology and Nephrology Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Zhongguan Lou
- Department of Urologic Surgery, Ningbo Urology and Nephrology Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Shuaishuai Huang
- Department of Urologic Surgery, Ningbo Urology and Nephrology Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Haihui Zhuang
- Center for Translational Medicine, Ningbo University School of Medicine, Ningbo, Zhejiang 315211, P.R. China
| | - Yuduo Wang
- Center for Translational Medicine, Ningbo University School of Medicine, Ningbo, Zhejiang 315211, P.R. China
| | - Guobin Weng
- Department of Urologic Surgery, Ningbo Urology and Nephrology Hospital, Ningbo, Zhejiang 315000, P.R. China
| | - Ping Wang
- Center for Translational Medicine, Ningbo University School of Medicine, Ningbo, Zhejiang 315211, P.R. China
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Sakamoto N, Ogawa M, Sadamoto K, Takeuchi M, Kataoka N. Mechanical Role of Nesprin-1-Mediated Nucleus-Actin Filament Binding in Cyclic Stretch-Induced Fibroblast Elongation. Cell Mol Bioeng 2017; 10:327-338. [PMID: 31719867 DOI: 10.1007/s12195-017-0487-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/07/2017] [Indexed: 11/26/2022] Open
Abstract
The intracellular mechanical link tethering the nucleus to the cytoskeleton has been suggested to be the linker of the nucleoskeleton and cytoskeleton (LINC) complex. Previous studies have reported that knockdown of nesprin-1, a component of the LINC complex that directly binds to actin filaments, suppresses cellular morphological response to mechanical stimuli. The relation between nesprin-1 knockdown and cellular morphological changes, however, remains unclear. In this study, we examined the mechanical role of nucleus-actin filament binding in morphological changes of fibroblasts exposed to cyclic stretching. After exposure to 10% cyclic stretching for 6 h, fibroblasts transfected with nesprin-1-specific small interfering RNA showed fewer elongated shapes compared with non-transfected cells. To further examine the mechanical role of the nucleus and nucleus-bound actin filaments, we applied cyclic stretching to fibroblasts treated with Trichostatin A (TSA), which decreases nuclear stiffness and thereby reduces nucleus-binding actin filament tension. TSA-treatment was found to induce more rounded cellular shapes than those of non-treated cells under both static and cyclic stretching conditions. These results suggest that the tension of nucleus-bound actin filaments plays an important role in the formation of elongated fibroblasts under cyclic stretching and that nesprin-1 knockdown causes a decrease of tension in nucleus-associated actin filaments.
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Affiliation(s)
- Naoya Sakamoto
- 1Department of Intelligent Mechanical Systems, Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo 191-0065 Japan
| | - Mai Ogawa
- 2Department of Medical Engineering, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193 Japan
| | - Kiyomi Sadamoto
- 2Department of Medical Engineering, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193 Japan
| | - Masaki Takeuchi
- 2Department of Medical Engineering, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193 Japan
| | - Noriyuki Kataoka
- 3Department of Mechanical Engineering, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamuramachi, Koriyama, Fukushima 963-8642 Japan
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Role of the Rho GTPase/Rho kinase signaling pathway in pathogenesis and treatment of glaucoma: Bench to bedside research. Exp Eye Res 2016; 158:23-32. [PMID: 27593914 DOI: 10.1016/j.exer.2016.08.023] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 08/25/2016] [Accepted: 08/31/2016] [Indexed: 12/14/2022]
Abstract
Glaucoma is a leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is considered to be a predominant risk factor for primary open angle glaucoma, the most prevalent form of glaucoma. Although the etiological mechanisms responsible for increased IOP are not completely clear, impairment in aqueous humor (AH) drainage through the conventional or trabecular pathway is recognized to be a primary cause in glaucoma patients. Importantly, lowering of IOP has been demonstrated to reduce progression of vision loss and is a mainstay of treatment for all types of glaucoma. Currently however, there are limited therapeutic options available for lowering IOP especially as it relates to enhancement of AH outflow through the trabecular pathway. Towards addressing this challenge, bench and bedside research conducted over the course of the last decade and a half has identified the significance of inhibiting Rho kinase for lowering IOP. Rho kinase is a downstream effector of Rho GTPase signaling that regulates actomyosin dynamics in numerous cell types. Studies from several laboratories have demonstrated that inhibition of Rho kinase lowers IOP via relaxation of the trabecular meshwork which enhances AH outflow. By contrast, activation of Rho GTPase/Rho kinase signaling in the trabecular outflow pathway increases IOP by altering the contractile, cell adhesive and permeability barrier characteristics of the trabecular meshwork and Schlemm's canal tissues, and by influencing extracellular matrix production and fibrotic activity. This article, written in honor of the late David Epstein, MD, summarizes findings from both basic and clinical studies that have been instrumental for recognition of the importance of the Rho/Rho kinase signaling pathway in regulation of AH outflow, and in the development of Rho kinase inhibitors as promising IOP- lowering agents for glaucoma treatment.
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11
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Sarantos MR, Papanikolaou T, Ellerby LM, Hughes RE. Pizotifen Activates ERK and Provides Neuroprotection in vitro and in vivo in Models of Huntington's Disease. J Huntingtons Dis 2016; 1:195-210. [PMID: 23393546 DOI: 10.3233/jhd-120033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Huntington's disease (HD) is a dominantly inherited neurodegenerative condition characterized by dysfunction in striatal and cortical neurons. There are currently no approved drugs known to slow the progression of HD. OBJECTIVE To facilitate the development of therapies for HD, we identified approved drugs that can ameliorate mutant huntingtin-induced toxicity in experimental models of HD. METHODS A chemical screen was performed in a mouse Hdh(Q111/Q111) striatal cell model of HD. This screen identified a set of structurally related approved drugs (pizotifen, cyproheptadine, and loxapine) that rescued cell death in this model. Pizotifen was subsequently evaluated in the R6/2 HD mouse model. RESULTS We found that in striatal Hdh(Q111/Q111) cells, pizotifen treatment caused transient ERK activation and inhibition of ERK activation prevented rescue of cell death in this model. In the R6/2 HD mouse model, treatment with pizotifen activated ERK in the striatum, reduced neurodegeneration and significantly enhanced motor performance. CONCLUSIONS These results suggest that pizotifen and related approved drugs may provide a basis for developing disease modifying therapeutic interventions for HD.
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Luo T, Roman P, Liu C, Sun X, Park Y, Hu B. Upregulation of the GEF-H1 pathway after transient cerebral ischemia. Exp Neurol 2014; 263:306-13. [PMID: 25447939 DOI: 10.1016/j.expneurol.2014.10.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 10/10/2014] [Accepted: 10/22/2014] [Indexed: 01/10/2023]
Abstract
The microtubule-dependent GEF-H1 pathway controls synaptic re-networking and overall gene expression via regulating cytoskeleton dynamics. Understanding this pathway after ischemia is essential to developing new therapies for neuronal function recovery. However, how the GEF-H1 pathway is regulated following transient cerebral ischemia remains unknown. This study employed a rat model of transient forebrain ischemia to investigate alterations of the GEF-H1 pathway using Western blotting, confocal and electron microscopy, dephosphorylation analysis, and pull-down assay. The GEF-H1 activity was significantly upregulated by: (i) dephosphorylation and (ii) translocation to synaptic membrane and nuclear structures during the early phase of reperfusion. GEF-H1 protein was then downregulated in the brain regions where neurons were destined to undergo delayed neuronal death, but markedly upregulated in neurons that were resistant to the same episode of cerebral ischemia. Consistently, GTP-RhoA, a GEF-H1 substrate, was significantly upregulated after brain ischemia. Electron microscopy further showed that neuronal microtubules were persistently depolymerized in the brain region where GEF-H1 protein was downregulated after brain ischemia. The results demonstrate that the GEF-H1 activity is significantly upregulated in both vulnerable and resistant brain regions in the early phase of reperfusion. However, GEF-H1 protein is downregulated in the vulnerable neurons but upregulated in the ischemic resistant neurons during the recovery phase after ischemia. The initial upregulation of GEF-H1 activity may contribute to excitotoxicity, whereas the late upregulation of GEF-H1 protein may promote neuroplasticity after brain ischemia.
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Affiliation(s)
- Tianfei Luo
- Neurochemistry Laboratory of Brain Injury, Shock Trauma & Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Department of Neurology, The First Teaching Hospital, Jilin University, Changchun, China
| | - Philip Roman
- Neurochemistry Laboratory of Brain Injury, Shock Trauma & Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Chunli Liu
- Neurochemistry Laboratory of Brain Injury, Shock Trauma & Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Xin Sun
- Neurochemistry Laboratory of Brain Injury, Shock Trauma & Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States; Department of Neurology, The First Teaching Hospital, Jilin University, Changchun, China
| | - Yujung Park
- Neurochemistry Laboratory of Brain Injury, Shock Trauma & Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States
| | - Bingren Hu
- Neurochemistry Laboratory of Brain Injury, Shock Trauma & Anesthesiology Research Center, University of Maryland School of Medicine, Baltimore, MD 21201, United States.
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Valor LM. Transcription, epigenetics and ameliorative strategies in Huntington's Disease: a genome-wide perspective. Mol Neurobiol 2014; 51:406-23. [PMID: 24788684 PMCID: PMC4309905 DOI: 10.1007/s12035-014-8715-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 04/11/2014] [Indexed: 12/18/2022]
Abstract
Transcriptional dysregulation in Huntington’s disease (HD) is an early event that shapes the brain transcriptome by both the depletion and ectopic activation of gene products that eventually affect survival and neuronal functions. Disruption in the activity of gene expression regulators, such as transcription factors, chromatin-remodeling proteins, and noncoding RNAs, accounts for the expression changes observed in multiple animal and cellular models of HD and in samples from patients. Here, I review the recent advances in the study of HD transcriptional dysregulation and its causes to finally discuss the possible implications in ameliorative strategies from a genome-wide perspective. To date, the use of genome-wide approaches, predominantly based on microarray platforms, has been successful in providing an extensive catalog of differentially regulated genes, including biomarkers aimed at monitoring the progress of the pathology. Although still incipient, the introduction of combined next-generation sequencing techniques is enhancing our comprehension of the mechanisms underlying altered transcriptional dysregulation in HD by providing the first genomic landscapes associated with epigenetics and the occupancy of transcription factors. In addition, the use of genome-wide approaches is becoming more and more necessary to evaluate the efficacy and safety of ameliorative strategies and to identify novel mechanisms of amelioration that may help in the improvement of current preclinical therapeutics. Finally, the major conclusions obtained from HD transcriptomics studies have the potential to be extrapolated to other neurodegenerative disorders.
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Affiliation(s)
- Luis M Valor
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, Av. Santiago Ramón y Cajal s/n, Sant Joan d'Alacant, 03550, Alicante, Spain,
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Di Pardo A, Amico E, Favellato M, Castrataro R, Fucile S, Squitieri F, Maglione V. FTY720 (fingolimod) is a neuroprotective and disease-modifying agent in cellular and mouse models of Huntington disease. Hum Mol Genet 2013; 23:2251-65. [PMID: 24301680 DOI: 10.1093/hmg/ddt615] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Huntington disease (HD) is a genetic neurodegenerative disorder for which there is currently no cure and no way to stop or even slow the brain changes it causes. In the present study, we aimed to investigate whether FTY720, the first approved oral therapy for multiple sclerosis, may be effective in HD models and eventually constitute an alternative therapeutic approach for the treatment of the disease. Here, we utilized preclinical target validation paradigms and examined the in vivo efficacy of chronic administration of FTY720 in R6/2 HD mouse model. Our findings indicate that FTY720 improved motor function, prolonged survival and reduced brain atrophy in R6/2 mice. The beneficial effect of FTY720 administration was associated with a significant strengthening of neuronal activity and connectivity and, with reduction of mutant huntingtin aggregates, and it was also paralleled by increased phosphorylation of mutant huntingtin at serine 13/16 residues that are predicted to attenuate protein toxicity.
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15
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DeGeer J, Lamarche-Vane N. Rho GTPases in neurodegeneration diseases. Exp Cell Res 2013; 319:2384-94. [PMID: 23830879 DOI: 10.1016/j.yexcr.2013.06.016] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
Abstract
Rho GTPases are molecular switches that modulate multiple intracellular signaling processes by means of various effector proteins. As a result, Rho GTPase activities are tightly spatiotemporally regulated in order to ensure homeostasis within the cell. Though the roles of Rho GTPases during neural development have been well documented, their participation during neurodegeneration has been far less characterized. Herein we discuss our current knowledge of the role and function of Rho GTPases and regulators during neurodegeneration, and highlight their potential as targets for therapeutic intervention in common neurodegenerative disorders.
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Affiliation(s)
- Jonathan DeGeer
- McGill University, Department of Anatomy and Cell Biology, Montreal, QC, Canada H3A 0C7
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MAP kinase phosphatase 1 (MKP-1/DUSP1) is neuroprotective in Huntington's disease via additive effects of JNK and p38 inhibition. J Neurosci 2013; 33:2313-25. [PMID: 23392662 DOI: 10.1523/jneurosci.4965-11.2013] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We previously demonstrated that sodium butyrate is neuroprotective in Huntington's disease (HD) mice and that this therapeutic effect is associated with increased expression of mitogen-activated protein kinase/dual-specificity phosphatase 1 (MKP-1/DUSP1). Here we show that enhancing MKP-1 expression is sufficient to achieve neuroprotection in lentiviral models of HD. Wild-type MKP-1 overexpression inhibited apoptosis in primary striatal neurons exposed to an N-terminal fragment of polyglutamine-expanded huntingtin (Htt171-82Q), blocking caspase-3 activation and significantly reducing neuronal cell death. This neuroprotective effect of MKP-1 was demonstrated to be dependent on its enzymatic activity, being ablated by mutation of its phosphatase domain and being attributed to inhibition of specific MAP kinases (MAPKs). Overexpression of MKP-1 prevented the polyglutamine-expanded huntingtin-induced activation of c-Jun N-terminal kinases (JNKs) and p38 MAPKs, whereas extracellular signal-regulated kinase (ERK) 1/2 activation was not altered by either polyglutamine-expanded Htt or MKP-1. Moreover, mutants of MKP-1 that selectively prevented p38 or JNK binding confirmed the important dual contributions of p38 and JNK regulation to MKP-1-mediated neuroprotection. These results demonstrate additive effects of p38 and JNK MAPK inhibition by MKP-1 without consequence to ERK activation in this striatal neuron-based paradigm. MKP-1 also provided neuroprotection in vivo in a lentiviral model of HD neuropathology in rat striatum. Together, these data extend previous evidence that JNK- and p38-mediated pathways contribute to HD pathogenesis and, importantly, show that therapies simultaneously inhibiting both JNK and p38 signaling pathways may lead to improved neuroprotective outcomes.
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Ludueña RF. A Hypothesis on the Origin and Evolution of Tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:41-185. [DOI: 10.1016/b978-0-12-407699-0.00002-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Ravikumar M, Jain S, Miller RH, Capadona JR, Selkirk SM. An organotypic spinal cord slice culture model to quantify neurodegeneration. J Neurosci Methods 2012; 211:280-8. [PMID: 22975474 DOI: 10.1016/j.jneumeth.2012.09.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 08/19/2012] [Accepted: 09/04/2012] [Indexed: 02/07/2023]
Abstract
Activated microglia cells have been implicated in the neurodegenerative process of Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis; however, the precise roles of microglia in disease progression are unclear. Despite these diseases having been described for more than a century, current FDA approved therapeutics are symptomatic in nature with little evidence to supporting a neuroprotective effect. Furthermore, identifying novel therapeutics remains challenging due to undetermined etiology, a variable disease course, and the paucity of validated targets. Here, we describe the use of a novel ex vivo spinal cord culture system that offers the ability to screen potential neuroprotective agents, while maintaining the complexity of the in vivo environment. To this end, we treated spinal cord slice cultures with lipopolysaccharide and quantified neuron viability in culture using measurements of axon length and FluoroJadeC intensity. To simulate a microglia-mediated response to cellular debris, antigens, or implanted materials/devices, we supplemented the culture media with increasing densities of microspheres, facilitating microglia-mediated phagocytosis of the particles, which demonstrated a direct correlation between the phagocytic activities of microglia and neuronal health. To validate our model's capacity to accurately depict neuroprotection, cultures were treated with resveratrol, which demonstrated enhanced neuronal health. Our results successfully demonstrate the use of this model to reproducibly quantify the extent of neurodegeneration through the measurement of axon length and FluoroJadeC intensity, and we suggest this model will allow for accurate, high-throughput screening, which could result in expedited success in translational efficacy of therapeutic agents to clinical trials.
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Affiliation(s)
- Madhumitha Ravikumar
- Department of Biomedical Engineering, Case Western Reserve University, School of Engineering, 2071 Martin Luther King Jr. Drive, Wickenden Bldg, Cleveland, OH 44106, USA
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Jaiswal M, Sandoval H, Zhang K, Bayat V, Bellen HJ. Probing mechanisms that underlie human neurodegenerative diseases in Drosophila. Annu Rev Genet 2012; 46:371-96. [PMID: 22974305 DOI: 10.1146/annurev-genet-110711-155456] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The fruit fly, Drosophila melanogaster, is an excellent organism for the study of the genetic and molecular basis of metazoan development. Drosophila provides numerous tools and reagents to unravel the molecular and cellular functions of genes that cause human disease, and the past decade has witnessed a significant expansion of the study of neurodegenerative disease mechanisms in flies. Here we review the interplay between oxidative stress and neuronal toxicity. We cover some of the studies that show how proteasome degradation of protein aggregates, autophagy, mitophagy, and lysosomal function affect the quality control mechanisms required for neuronal survival. We discuss how forward genetic screens in flies have led to the isolation of a few loci that cause neurodegeneration, paving the way for large-scale systematic screens to identify such loci in flies as well as promoting gene discovery in humans.
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Affiliation(s)
- M Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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Ramaswamy S, Kordower JH. Gene therapy for Huntington's disease. Neurobiol Dis 2011; 48:243-54. [PMID: 22222669 DOI: 10.1016/j.nbd.2011.12.030] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 12/01/2011] [Accepted: 12/14/2011] [Indexed: 12/30/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disease for which there is no cure. Therapies that are efficacious in animal models have to date shown benefit for humans. One potential powerful approach is gene therapy. The ideal method of administration of gene therapy has been hotly debated and viral vectors have provided one method of long-term and wide-spread delivery to the brain. Trophic factors to protect cells from degeneration and RNAi to reduce mutant huntingtin (mHtt) protein expression are 2 main classes of compounds that demonstrate benefit in animal models. This review will examine some commonly used adeno-associated viral (AAV) vectors and discuss some therapies that hold promise for HD.
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Affiliation(s)
- Shilpa Ramaswamy
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA
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Bodai L, Marsh JL. A novel target for Huntington's disease: ERK at the crossroads of signaling. Bioessays 2011; 34:142-8. [DOI: 10.1002/bies.201100116] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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