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Hu Y, Lauffer P, Jongejan A, Falize K, Bruinstroop E, van Trotsenburg P, Fliers E, Hennekam RC, Boelen A. Analysis of genes differentially expressed in the cortex of mice with the Tbl1xr1 Y446C/Y446C variant. Gene 2024; 927:148707. [PMID: 38885822 DOI: 10.1016/j.gene.2024.148707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/09/2024] [Accepted: 06/14/2024] [Indexed: 06/20/2024]
Abstract
Transducin β-like 1 X-linked receptor 1 (mouse Tbl1xr1) or TBL1X/Y related 1 (human TBL1XR1), part of the NCoR/SMRT corepressor complex, is involved in nuclear receptor signaling. Variants in TBL1XR1 cause a variety of neurodevelopmental disorders including Pierpont syndrome caused by the p.Tyr446Cys variant. We recently reported a mouse model carrying the Tbl1xr1Y446C/Y446C variant as a model for Pierpont syndrome. To obtain insight into mechanisms involved in altered brain development we studied gene expression patterns in the cortex of mutant and wild type (WT) mice, using RNA-sequencing, differentially expressed gene (DEG) analysis, gene set enrichment analysis (GSEA), weighted gene correlation network analysis (WGCNA) and hub gene analysis. We validated results in mutated mouse cortex, as well as in BV2 and SK-N-AS cell lines, in both of which Tbl1xr1 was knocked down by siRNA. Two DEGs (adj.P. Val < 0.05) were found in the cortex, Mpeg1 (downregulated in mutant mice) and 2900052N01Rik (upregulated in mutant mice). GSEA, WGCNA and hub gene analysis demonstrated changes in genes involved in ion channel function and neuroinflammation in the cortex of the Tbl1xr1Y446C/Y446C mice. The lowered expression of ion channel genes Kcnh3 and Kcnj4 mRNA was validated in the mutant mouse cortex, and increased expression of TRIM9, associated with neuroinflammation, was confirmed in the SK-N-AS cell line. Conclusively, our results show altered expression of genes involved in ion channel function and neuroinflammation in the cortex of the Tbl1xr1Y446C/Y446C mice. These may partly explain the impaired neurodevelopment observed in individuals with Pierpont syndrome and related TBL1XR1-related disorders.
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Affiliation(s)
- Yalan Hu
- Endocrine Laboratory, Department of Laboratory Medicine, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Peter Lauffer
- Department of Pediatric Endocrinology, Emma Children's Hospital, University of Amsterdam, Amsterdam, the Netherlands; Research Institute Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Aldo Jongejan
- Department of Epidemiology and Data Science, Bioinformatics Laboratory, Amsterdam UMC Location AMC, University of Amsterdam, Amsterdam, the Netherlands; Research Institute Amsterdam Public Health, Methodology, Amsterdam, the Netherlands
| | - Kim Falize
- Endocrine Laboratory, Department of Laboratory Medicine, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Eveline Bruinstroop
- Research Institute Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Paul van Trotsenburg
- Department of Pediatric Endocrinology, Emma Children's Hospital, University of Amsterdam, Amsterdam, the Netherlands; Research Institute Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Eric Fliers
- Research Institute Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Raoul C Hennekam
- Department of Pediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Anita Boelen
- Endocrine Laboratory, Department of Laboratory Medicine, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Research Institute Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.
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Ildarabadi A, Mir Mohammad Ali SN, Rahmani F, Mosavari N, Pourbakhtyaran E, Rezaei N. Inflammation and oxidative stress in epileptic children: from molecular mechanisms to clinical application of ketogenic diet. Rev Neurosci 2024; 35:473-488. [PMID: 38347675 DOI: 10.1515/revneuro-2023-0128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 12/18/2023] [Indexed: 06/02/2024]
Abstract
Childhood epilepsy affects up to 1 % of children. It has been shown that 30 % of patients are resistant to drug treatments, making further investigation of other potential treatment strategies necessary. One such approach is the ketogenic diet (KD) showing promising results and potential benefits beyond the use of current antiepileptic drugs. This study aims to investigate the effects of KD on inflammation and oxidative stress, as one of the main suggested mechanisms of neuroprotection, in children with epilepsy. This narrative review was conducted using the Medline and Google Scholar databases, and by searching epilepsy, drug-resistant epilepsy, child, children, ketogenic, ketogenic diet, diet, ketogenic, keto, ketone bodies (BHB), PUFA, gut microbiota, inflammation, inflammation mediators, neurogenic inflammation, neuroinflammation, inflammatory marker, adenosine modulation, mitochondrial function, MTOR pathway, Nrf2 pathway, mitochondrial dysfunction, PPARɣ, oxidative stress, ROS/RNS, and stress oxidative as keywords. Compelling evidence underscores inflammation and oxidative stress as pivotal factors in epilepsy, even in cases with genetic origins. The ketogenic diet effectively addresses these factors by reducing ROS and RNS, enhancing antioxidant defenses, improving mitochondrial function, and regulating inflammatory genes. Additionally, KD curbs pro-inflammatory cytokine and chemokine production by dampening NF-κB activation, inhibiting the NLRP3 inflammasome, increasing brain adenosine levels, mTOR pathway inhibition, upregulating PPARɣ expression, and promoting a healthy gut microbiota while emphasizing the consumption of healthy fats. KD could be considered a promising therapeutic intervention in patients with epilepsy particularly in drug-resistant epilepsy cases, due to its targeted approach addressing oxidative stress and inflammatory mechanisms.
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Affiliation(s)
- Azam Ildarabadi
- Department of Nutrition Science, Science and Research Branch, Faculty of Medical Science and Technology, Islamic Azad University, Shodada Hesarak Blvd, Tehran 1477893855, Iran
- Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Dr. Qarib St, Tehran 1419733151, Iran
| | - Seyedeh Nooshan Mir Mohammad Ali
- Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Dr. Qarib St, Tehran 1419733151, Iran
- Department of Food, Nutrition, Dietetics and Health, Kansas State University, Manhattan, KS 66502, USA
| | - Fatemeh Rahmani
- Department of Nutrition Science, Science and Research Branch, Faculty of Medical Science and Technology, Islamic Azad University, Shodada Hesarak Blvd, Tehran 1477893855, Iran
- Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Dr. Qarib St, Tehran 1419733151, Iran
| | - Narjes Mosavari
- Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Dr. Qarib St, Tehran 1419733151, Iran
| | - Elham Pourbakhtyaran
- Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Dr. Qarib St, Tehran 1419733151, Iran
- Department of Pediatric Neurology, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Dr. Qarib St, Tehran 1419733151, Iran
| | - Nima Rezaei
- Network of Interdisciplinarity in Neonates and Infants (NINI), Universal Scientific Education and Research Network (USERN), Dr. Qarib St, Tehran 1419733151, Iran
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center Hospital, Tehran University of Medical Sciences, Dr. Qarib St, Tehran 1419733151, Iran
- Department of Immunology, School of Medicine, Tehran University of Medical Science, Pour Sina St, Tehran 1461884513, Iran
- Research Center for Immunodeficiencies, Children's Medical Center Hospital, Dr. Qarib St, Keshavarz Blvd, Tehran 14194, Iran
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Verhoog QP, Holtman L, Aronica E, van Vliet EA. Astrocytes as Guardians of Neuronal Excitability: Mechanisms Underlying Epileptogenesis. Front Neurol 2020; 11:591690. [PMID: 33324329 PMCID: PMC7726323 DOI: 10.3389/fneur.2020.591690] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are key homeostatic regulators in the central nervous system and play important roles in physiology. After brain damage caused by e.g., status epilepticus, traumatic brain injury, or stroke, astrocytes may adopt a reactive phenotype. This process of reactive astrogliosis is important to restore brain homeostasis. However, persistent reactive astrogliosis can be detrimental for the brain and contributes to the development of epilepsy. In this review, we will focus on physiological functions of astrocytes in the normal brain as well as pathophysiological functions in the epileptogenic brain, with a focus on acquired epilepsy. We will discuss the role of astrocyte-related processes in epileptogenesis, including reactive astrogliosis, disturbances in energy supply and metabolism, gliotransmission, and extracellular ion concentrations, as well as blood-brain barrier dysfunction and dysregulation of blood flow. Since dysfunction of astrocytes can contribute to epilepsy, we will also discuss their role as potential targets for new therapeutic strategies.
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Affiliation(s)
- Quirijn P. Verhoog
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Linda Holtman
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
| | - Eleonora Aronica
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Erwin A. van Vliet
- Department of Neuropathology, Amsterdam Neuroscience, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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Abstract
AbstractEpilepsy is a chronic neurological disorder that has an extensive impact on a patient’s life. Accumulating evidence has suggested that inflammation participates in the progression of spontaneous and recurrent seizures. Pro-convulsant incidences can stimulate immune cells, augment the release of pro-inflammatory cytokines, elicit neuronal excitation as well as blood-brain barrier (BBB) dysfunction, and finally trigger the generation or recurrence of seizures. Understanding the pathogenic roles of inflammatory mediators, including inflammatory cytokines, cells, and BBB, in epileptogenesis will be beneficial for the treatment of epilepsy. In this systematic review, we performed a literature search on the PubMed database using the following keywords: “epilepsy” or “seizures” or “epileptogenesis”, and “immunity” or “inflammation” or “neuroinflammation” or “damage-associated molecular patterns” or “cytokines” or “chemokines” or “adhesion molecules” or “microglia” or “astrocyte” or “blood-brain barrier”. We summarized the classic inflammatory mediators and their pathogenic effects in the pathogenesis of epilepsy, based on the most recent findings from both human and animal model studies.
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Khakipoor S, Ophoven C, Schrödl‐Häußel M, Feuerstein M, Heimrich B, Deitmer JW, Roussa E. TGF-β signaling directly regulates transcription and functional expression of the electrogenic sodium bicarbonate cotransporter 1, NBCe1 (SLC4A4), via Smad4 in mouse astrocytes. Glia 2017; 65:1361-1375. [PMID: 28568893 PMCID: PMC5518200 DOI: 10.1002/glia.23168] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/27/2017] [Accepted: 05/04/2017] [Indexed: 02/06/2023]
Abstract
The electrogenic sodium bicarbonate cotransporter NBCe1 (SLC4A4) expressed in astrocytes regulates intracellular and extracellular pH. Here, we introduce transforming growth factor beta (TGF-β) as a novel regulator of NBCe1 transcription and functional expression. Using hippocampal slices and primary hippocampal and cortical astrocyte cultures, we investigated regulation of NBCe1 and elucidated the underlying signaling pathways by RT-PCR, immunoblotting, immunofluorescence, intracellular H(+ ) recording using the H(+ ) -sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein, mink lung epithelial cell (MLEC) assay, and chromatin immunoprecipitation. Activation of TGF-β signaling significantly upregulated transcript, protein, and surface expression of NBCe1. These effects were TGF-β receptor-mediated and suppressed following inhibition of JNK and Smad signaling. Moreover, 4-aminopyridine (4AP)-dependent NBCe1 regulation requires TGF-β. TGF-β increased the rate and amplitude of intracellular H+ changes upon challenging NBCe1 in wild-type astrocytes but not in cortical astrocytes from Slc4a4-deficient mice. A Smad4 binding sequence was identified in the NBCe1 promoter and Smad4 binding increased after activation of TGF-β signaling. The data show for the first time that NBCe1 is a direct target of TGF-β/Smad4 signaling. Through activation of the canonical pathway TGF-β acts directly on NBCe1 by binding of Smad4 to the NBCe1 promoter and regulating its transcription, followed by increased protein expression and transport activity.
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Affiliation(s)
- Shokoufeh Khakipoor
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Christian Ophoven
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Magdalena Schrödl‐Häußel
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Melanie Feuerstein
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Bernd Heimrich
- Department of NeuroanatomyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
| | - Joachim W. Deitmer
- Department of General ZoologyFB Biology, University of KaiserslauternP.B. 3049D‐67653KaiserslauternGermany
| | - Eleni Roussa
- Department of Molecular EmbryologyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
- Department of NeuroanatomyInstitute for Anatomy and Cell Biology, Faculty of Medicine, University of FreiburgAlbertstrasse 17D‐79104FreiburgGermany
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Transforming growth factor β1 enhances heme oxygenase 1 expression in human synovial fibroblasts by inhibiting microRNA 519b synthesis. PLoS One 2017; 12:e0176052. [PMID: 28423042 PMCID: PMC5397058 DOI: 10.1371/journal.pone.0176052] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 04/04/2017] [Indexed: 01/15/2023] Open
Abstract
Background Osteoarthritis (OA) is manifested by synovial inflammation and cartilage destruction that is directly linked to synovitis, joint swelling and pain. In the light of the role of synovium in the pathogenesis and the symptoms of OA, synovium-targeted therapy is a promising strategy to mitigate the symptoms and progression of OA. Transforming growth factor beta 1 (TGF-β1), a secreted homodimeric protein, possesses unique and potent anti-inflammatory and immune-regulatory properties in many cell types. Heme oxygenase 1 (HO-1) is an inducible anti-inflammatory and stress responsive enzyme that has been proven to prevent injuries caused by many diseases. Despite the similar anti-inflammatory profile and their involvement in the pathogenesis of arthritic diseases, no studies have as yet explored the possibility of any association between the expression of TGF-β1 and HO-1. Methodology/Principal findings TGF-β1-induced HO-1 expression was examined by HO-1 promoter assay, qPCR, and Western blotting. The siRNAs and enzyme inhibitors were utilized to determine the intermediate involved in the signal transduction pathway. We showed that TGF-β1 stimulated the synthesis of HO-1 in a concentration- and time-dependent manner, which can be mitigated by blockade of the phospholipase (PLC)γ/protein kinase C alpha (PKC)α pathway. We also showed that the expression of miRNA-519b, which blocks HO-1 transcription, is inhibited by TGF-β1, and the suppression of miRNA 519b could be reversed via blockade of the PLCγ/PKCα pathway. Conclusions/Significance TGF-β1 stimulated the expression of HO-1 via activating the PLCγ/PKCα pathway and suppressing the downstream expression of miRNA-519b. These results may shed light on the pathogenesis and treatment of OA.
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Wang F, Wang X, Shapiro LA, Cotrina ML, Liu W, Wang EW, Gu S, Wang W, He X, Nedergaard M, Huang JH. NKCC1 up-regulation contributes to early post-traumatic seizures and increased post-traumatic seizure susceptibility. Brain Struct Funct 2016; 222:1543-1556. [PMID: 27586142 PMCID: PMC5368191 DOI: 10.1007/s00429-016-1292-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 08/16/2016] [Indexed: 11/15/2022]
Abstract
Traumatic brain injury (TBI) is not only a leading cause for morbidity and mortality in young adults (Bruns and Hauser, Epilepsia 44(Suppl 10):210, 2003), but also a leading cause of seizures. Understanding the seizure-inducing mechanisms of TBI is of the utmost importance, because these seizures are often resistant to traditional first- and second-line anti-seizure treatments. The early post-traumatic seizures, in turn, are a contributing factor to ongoing neuropathology, and it is critically important to control these seizures. Many of the available anti-seizure drugs target gamma-aminobutyric acid (GABAA) receptors. The inhibitory activity of GABAA receptor activation depends on low intracellular Cl−, which is achieved by the opposing regulation of Na+–K+–Cl− cotransporter 1 (NKCC1) and K+–Cl−–cotransporter 2 (KCC2). Up-regulation of NKCC1 in neurons has been shown to be involved in neonatal seizures and in ammonia toxicity-induced seizures. Here, we report that TBI-induced up-regulation of NKCC1 and increased intracellular Cl− concentration. Genetic deletion of NKCC1 or pharmacological inhibition of NKCC1 with bumetanide suppresses TBI-induced seizures. TGFβ expression was also increased after TBI and competitive antagonism of TGFβ reduced NKKC1 expression, ameliorated reactive astrocytosis, and inhibited seizures. Thus, TGFβ might be an important pathway involved in NKCC1 up-regulation after TBI. Our findings identify neuronal up-regulation of NKCC1 and its mediation by TGFβ, as a potential and important mechanism in the early post-traumatic seizures, and demonstrate the therapeutic potential of blocking this pathway.
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Affiliation(s)
- Fushun Wang
- Nanjing University of Chinese Medicine, Nanjing, 210023, China.,Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester, Rochester, NY, 14642, USA.,Department of Surgery, Texas A&M University Health Science Center, College of Medicine, Temple, TX, 76504, USA.,Department of Neurosurgery, Neuroscience Institute, Baylor Scott and White Health, Central Division, Temple, TX, 76508, USA
| | - Xiaowei Wang
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester, Rochester, NY, 14642, USA.,Neuroscience Graduate Program, University of Rochester, Rochester, NY, 14642, USA
| | - Lee A Shapiro
- Department of Surgery, Texas A&M University Health Science Center, College of Medicine, Temple, TX, 76504, USA.
| | - Maria L Cotrina
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester, Rochester, NY, 14642, USA
| | - Weimin Liu
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester, Rochester, NY, 14642, USA
| | - Ernest W Wang
- Department of Neurosurgery, Neuroscience Institute, Baylor Scott and White Health, Central Division, Temple, TX, 76508, USA
| | - Simeng Gu
- Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Wei Wang
- Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Xiaosheng He
- Department of Neurosurgery, Xijing Hospital, 4th Military Medical University, Xi'an, China
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Rochester, Rochester, NY, 14642, USA
| | - Jason H Huang
- Department of Surgery, Texas A&M University Health Science Center, College of Medicine, Temple, TX, 76504, USA. .,Department of Neurosurgery, Neuroscience Institute, Baylor Scott and White Health, Central Division, Temple, TX, 76508, USA.
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Jukkola P, Gu C. Regulation of neurovascular coupling in autoimmunity to water and ion channels. Autoimmun Rev 2015; 14:258-67. [PMID: 25462580 PMCID: PMC4303502 DOI: 10.1016/j.autrev.2014.11.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 11/15/2014] [Indexed: 12/27/2022]
Abstract
Much progress has been made in understanding autoimmune channelopathies, but the underlying pathogenic mechanisms are not always clear due to broad expression of some channel proteins. Recent studies show that autoimmune conditions that interfere with neurovascular coupling in the central nervous system (CNS) can lead to neurodegeneration. Cerebral blood flow that meets neuronal activity and metabolic demand is tightly regulated by local neural activity. This process of reciprocal regulation involves coordinated actions of a number of cell types, including neurons, glia, and vascular cells. In particular, astrocytic endfeet cover more than 90% of brain capillaries to assist blood-brain barrier (BBB) function, and wrap around synapses and nodes of Ranvier to communicate with neuronal activity. In this review, we highlight four types of channel proteins that are expressed in astrocytes, regarding their structures, biophysical properties, expression and distribution patterns, and related diseases including autoimmune disorders. Water channel aquaporin 4 (AQP4) and inwardly rectifying potassium (Kir4.1) channels are concentrated in astrocytic endfeet, whereas some voltage-gated Ca(2+) and two-pore domain K(+) channels are expressed throughout the cell body of reactive astrocytes. More channel proteins are found in astrocytes under normal and abnormal conditions. This research field will contribute to a better understanding of pathogenic mechanisms underlying autoimmune disorders.
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Affiliation(s)
- Peter Jukkola
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Chen Gu
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH 43210, USA; Department of Neuroscience, The Ohio State University, Columbus, OH 43210, USA.
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Gibbons M, Smeal R, Takahashi D, Vargas J, Wilcox K. Contributions of astrocytes to epileptogenesis following status epilepticus: opportunities for preventive therapy? Neurochem Int 2013; 63:660-9. [PMID: 23266599 PMCID: PMC4353644 DOI: 10.1016/j.neuint.2012.12.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 12/09/2012] [Accepted: 12/13/2012] [Indexed: 12/22/2022]
Abstract
Status epilepticus (SE) is a life threatening condition that often precedes the development of epilepsy. Traditional treatments for epilepsy have been focused on targeting neuronal mechanisms contributing to hyperexcitability, however, approximately 30% of patients with epilepsy do not respond to existing neurocentric pharmacotherapies. A growing body of evidence has demonstrated that profound changes in the morphology and function of astrocytes accompany SE and persist in epilepsy. Astrocytes are increasingly recognized for their diverse roles in modulating neuronal activity, and understanding the changes in astrocytes following SE could provide important clues about the mechanisms underlying seizure generation and termination. By understanding the contributions of astrocytes to the network changes underlying epileptogenesis and the development of epilepsy, we will gain a greater appreciation of the contributions of astrocytes to dynamic circuit changes, which will enable us to develop more successful therapies to prevent and treat epilepsy. This review summarizes changes in astrocytes following SE in animal models and human temporal lobe epilepsy and addresses the functional consequences of those changes that may provide clues to the process of epileptogenesis.
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Affiliation(s)
- M.B. Gibbons
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT
| | - R.M. Smeal
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT
| | - D.K. Takahashi
- Department of Neurology, Stanford University, Palo Alto, CA
| | - J.R. Vargas
- Department of Neurology, University of Utah, Salt Lake City, UT
| | - K.S. Wilcox
- Interdepartmental Program in Neuroscience, University of Utah, Salt Lake City, UT
- Department of Pharmacology & Toxicology, University of Utah, Salt Lake City, UT
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Gieseler F, Ungefroren H, Settmacher U, Hollenberg MD, Kaufmann R. Proteinase-activated receptors (PARs) - focus on receptor-receptor-interactions and their physiological and pathophysiological impact. Cell Commun Signal 2013; 11:86. [PMID: 24215724 PMCID: PMC3842752 DOI: 10.1186/1478-811x-11-86] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 10/25/2013] [Indexed: 02/07/2023] Open
Abstract
Proteinase-activated receptors (PARs) are a subfamily of G protein-coupled receptors (GPCRs) with four members, PAR1, PAR2, PAR3 and PAR4, playing critical functions in hemostasis, thrombosis, embryonic development, wound healing, inflammation and cancer progression. PARs are characterized by a unique activation mechanism involving receptor cleavage by different proteinases at specific sites within the extracellular amino-terminus and the exposure of amino-terminal “tethered ligand“ domains that bind to and activate the cleaved receptors. After activation, the PAR family members are able to stimulate complex intracellular signalling networks via classical G protein-mediated pathways and beta-arrestin signalling. In addition, different receptor crosstalk mechanisms critically contribute to a high diversity of PAR signal transduction and receptor-trafficking processes that result in multiple physiological effects. In this review, we summarize current information about PAR-initiated physical and functional receptor interactions and their physiological and pathological roles. We focus especially on PAR homo- and heterodimerization, transactivation of receptor tyrosine kinases (RTKs) and receptor serine/threonine kinases (RSTKs), communication with other GPCRs, toll-like receptors and NOD-like receptors, ion channel receptors, and on PAR association with cargo receptors. In addition, we discuss the suitability of these receptor interaction mechanisms as targets for modulating PAR signalling in disease.
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Affiliation(s)
| | | | | | | | - Roland Kaufmann
- Department of General, Visceral and Vascular Surgery, Experimental Transplantation Surgery, Jena University Hospital, Drackendorfer Str, 1, D-07747, Jena, Germany.
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Yellen P, Chatterjee A, Preda A, Foster DA. Inhibition of S6 kinase suppresses the apoptotic effect of eIF4E ablation by inducing TGF-β-dependent G1 cell cycle arrest. Cancer Lett 2013; 333:239-43. [PMID: 23376634 DOI: 10.1016/j.canlet.2013.01.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 01/23/2013] [Accepted: 01/23/2013] [Indexed: 10/27/2022]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of cap-dependent translation through its direct activation of ribosomal protein p70 S6 kinase (S6 kinase) and indirect activation of eukaryotic initiation factor 4E (eIF4E). We recently reported that inhibition of eIF4E expression caused apoptosis in cancer cells in the absence of serum. This was indicated by treatment with the mTORC1 inhibitor rapamycin, which suppressed both S6 kinase and 4E-BP1 phosphorylation (dephosphorylated 4E-BP1 binds and inactivates eIF4E), or by knockdown of eIF4E. We report here that knockdown of eIF4E also causes apoptosis in the presence of serum. This was unexpected because rapamycin induces G1 cell cycle arrest in the presence of serum. Upon investigation, we have found that inactivated S6 kinase prevents the apoptotic effect observed by singular knockdown of eIF4E and results in G1 cell cycle arrest. This effect is dependent on TGF-β (transforming growth factor-β) signaling which contributes to G1 cell cycle arrest. Suppression of S6 kinase phosphorylation alone is insufficient to mediate cell cycle arrest, indicating that complete G1 cell cycle arrest is due to suppression of both S6 kinase and eIF4E. These data indicate that the cytostatic effect of rapamycin is suppression of both S6 kinase and eIF4E, while the cytotoxic effects are due suppression of eIF4E in the absence of S6 kinase-dependent activation of TGF-β signals. Our findings place an importance on the evaluating the activity/expression level of S6 kinase and eIF4E as readouts for rapamycin/rapalog efficacy.
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Affiliation(s)
- Paige Yellen
- Department of Biological Sciences, Hunter College of The City University of New York, 695 Park Avenue, New York, NY 10065, USA
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Frigerio F, Frasca A, Weissberg I, Parrella S, Friedman A, Vezzani A, Noé FM. Long-lasting pro-ictogenic effects induced in vivo by rat brain exposure to serum albumin in the absence of concomitant pathology. Epilepsia 2012; 53:1887-97. [PMID: 22984896 PMCID: PMC3651831 DOI: 10.1111/j.1528-1167.2012.03666.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE Dysfunction of the blood-brain barrier (BBB) is a common finding during seizures or following epileptogenic brain injuries, and experimentally induced BBB opening promotes seizures both in naive and epileptic animals. Brain albumin extravasation was reported to promote hyperexcitability by inducing astrocytes dysfunction. To provide in vivo evidence for a direct role of extravasated serum albumin in seizures independently on the pathologic context, we did the following: (1) quantified the amount of serum albumin extravasated in the rat brain parenchyma during status epilepticus (SE); (2) reproduced a similar concentration in the hippocampus by intracerebroventricular (i.c.v.) albumin injection in naive rats; (3) measured electroencephalography (EEG) activity in these rats, their susceptibility to kainic acid (KA)-induced seizures, and their hippocampal afterdischarge threshold (ADT). METHODS Brain albumin concentration was measured in the rat hippocampus and other forebrain regions 2 and 24 h after SE by western blot analysis. Brain distribution of serum albumin or fluorescein isothiocyanate (FITC)-albumin was studied by immunohistochemistry and immunofluorescence, respectively. Naive rats were injected with rat albumin or FITC-albumin, i.c.v., to mimic the brain concentration attained after SE, or with dextran used as control. Inflammation was evaluated by immunohistochemistry by measuring glial induction of interleukin (IL)-1β. Western blot analysis was used to measure inward rectifying potassium channel subunit Kir4.1 protein levels in the hippocampus. Seizures were induced in rats by intrahippocampal injection of 80 ng KA and quantified by EEG analysis, 2 or 24 h after rat albumin or dextran administration. ADT was measured by electrical stimulation of the hippocampus 3 months after albumin injection. In these rats, EEG was continuously monitored for 2 weeks to search for spontaneous seizures. KEY FINDINGS The hippocampal serum albumin concentration 24 h post-SE was 0.76 ± 0.21 μm. Similar concentrations were measured in other forebrain regions, whereas no changes were found in cerebellum. The hippocampal albumin concentration was similarly reproduced in naive rats by i.c.v. administration of 500 μg/4 μl rat albumin: albumin was predominantly detected extracellularly 2 h after injection, whereas at 24 h it was visible inside pyramidal neurons and in only a few scattered chondroitin sulphate proteoglycan (NG2)-positive cells, but not in glial fibrillary acidic protein (GFAP)-positive astrocytes or CR-3 complement receptor (OX-42)-positive microglia. The presence of albumin in naive rat hippocampus was associated with induced IL-1β in GFAP-positive astrocytes and a concomitant tissue down-regulation of Kir4.1. Spiking activity was evoked by albumin in the hippocampus lasting for 2 h. When KA was intrahippocampally applied either 2 or 24 h after albumin injection, the number of total interictal spikes in 3 h EEG recording was significantly increased by twofold on average. Three months after albumin injection, neither albumin nor inflammation was detected in brain tissue; at this time, the ADT was reduced by 50% but no spontaneous seizures were observed. SIGNIFICANCE Transient hippocampal exposure to albumin levels similar to those attained after prominent BBB breakdown resulted in increased seizure susceptibility and long-term reduction in seizure threshold, but it did not evoke spontaneous seizures. These effects may be mediated by albumin-induced astrocytes dysfunction and the associated induction of proinflammatory molecules.
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Affiliation(s)
- Federica Frigerio
- Department of Neuroscience, Mario Negri Institute for Pharmacological Research, Via G. La Masa 19, Milan, Italy.
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HEINEMANN UWE, KAUFER DANIELA, FRIEDMAN ALON. Blood-brain barrier dysfunction, TGFβ signaling, and astrocyte dysfunction in epilepsy. Glia 2012; 60:1251-7. [PMID: 22378298 PMCID: PMC3615248 DOI: 10.1002/glia.22311] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 01/27/2012] [Indexed: 11/11/2022]
Abstract
Brain insults, including traumatic and ischemic injuries, are frequently followed by acute seizures and delayed development of epilepsy. Dysfunction of the blood-brain barrier (BBB) is a hallmark of brain insults and is usually surrounding the core lesion. Recent studies from several laboratories confirmed that vascular pathology is involved in the development of epilepsy and demonstrate a key role for astroglia in this process. In this review, we focus on glia-related mechanisms linking vascular pathology, and specifically BBB dysfunction, to seizures and epilepsy. We summarize molecular and physiological experimental data demonstrating that the function of astrocytes is altered due to direct exposure to serum albumin, mediated by transforming growth factor beta signaling. We discuss the reported changes and their potential role in the observed hyperexcitability as well as potential implications of these findings for the future development of new diagnostic modalities and treatments to allow a full implementation of the gained knowledge for the benefit of patients with epilepsy.
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Affiliation(s)
- UWE HEINEMANN
- Institute of Neurophysiology, Charité Universitätsmedizin, Berlin
| | - DANIELA KAUFER
- Department of Integrative Biology, Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, California
| | - ALON FRIEDMAN
- Department of Physiology and Neurobiology, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Correspondence to: Alon Friedman, Department of Physiology, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
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Swayne LA, Wicki-Stordeur L. Ion channels in postnatal neurogenesis: potential targets for brain repair. Channels (Austin) 2012; 6:69-74. [PMID: 22614818 DOI: 10.4161/chan.19721] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Neural stem and progenitor cells (NSC/NPCs) are unspecialized cells found in the adult peri-ventricular and sub-granular zones that are capable of self-renewal, migration, and differentiation into new neurons through the remarkable process of postnatal neurogenesis. We are now beginning to understand that the concerted action of ion channels, multi-pass transmembrane proteins that allow passage of ions across otherwise impermeable cellular membranes tightly regulate this process. Specific ion channels control proliferation, differentiation and survival. Furthermore, they have the potential to be highly selective drug targets due to their complex structures. As such, these proteins represent intriguing prospects for control and optimization of postnatal neurogenesis for neural regeneration following brain injury or disease. Here, we concentrate on ion channels identified in adult ventricular zone NSC/NPCs that have been found to influence the stages of neurogenesis. Finally, we outline the potential of these channels to elicit repair, and highlight the outstanding challenges.
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Affiliation(s)
- Leigh Anne Swayne
- Division of Medical Sciences; Island Medical Program, University of Victoria, Victoria, BC, Canada.
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15
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Ramos-Mondragón R, Vega AV, Avila G. Long-term modulation of Na+ and K+ channels by TGF-β1 in neonatal rat cardiac myocytes. Pflugers Arch 2011; 461:235-47. [PMID: 21229261 DOI: 10.1007/s00424-010-0912-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 11/16/2010] [Accepted: 12/04/2010] [Indexed: 12/19/2022]
Abstract
Previous work shows that transforming growth factor-β1 (TGF-β1) promotes several heart alterations, including atrial fibrillation (AF). In this work, we hypothesized that these effects might be associated with a potential modulation of Na(+) and K(+) channels. Atrial myocytes were cultured 1-2 days under either control conditions, or the presence of TGF-β1. Subsequently, Na(+) (I(Na)) and K(+) (I(K)) currents were investigated under whole-cell patch-clamp conditions. Three K(+) currents were isolated: inward rectifier (I(Kin)), outward transitory (I(to)), and outward sustained (I(Ksus)). Interestingly, TGF-β1 decreased (50%) the densities of I(Kin) and I(Ksus) but not of I(to). In addition, the growth factor reduced by 80% the amount of I(Na) available at -80 mV. This effect was due to a significant reduction (30%) in the maximum I(Na) recruited at very negative potentials or I(max), as well as to an increased fraction of inactivated Na(+) channels. The latter effect was, in turn, associated to a -7 mV shift in V(1/2) of inactivation. TGF-β1 also reduced by 60% the maximum amount of intramembrane charge movement of Na(+) channels or Q(max), but did not affect the corresponding voltage dependence of activation. This suggests that TGF-β1 promotes loss of Na(+) channels from the plasma membrane. Moreover, TGF-β1 also reduced (50%) the expression of the principal subunit of Na(+) channels, as indicated by western blot analysis. Thus, TGF-β1 inhibits the expression of Na(+) channels, as well as the activity of K(+) channels that give rise to I(Ksus) and I(Kin). These results may contribute to explaining the previously observed proarrhythmic effects of TGF-β1.
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16
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Voigt N, Trausch A, Knaut M, Matschke K, Varró A, Van Wagoner DR, Nattel S, Ravens U, Dobrev D. Left-to-right atrial inward rectifier potassium current gradients in patients with paroxysmal versus chronic atrial fibrillation. Circ Arrhythm Electrophysiol 2010; 3:472-80. [PMID: 20657029 DOI: 10.1161/circep.110.954636] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Recent evidence suggests that atrial fibrillation (AF) is maintained by high-frequency reentrant sources with a left-to-right-dominant frequency gradient, particularly in patients with paroxysmal AF (pAF). Unequal left-to-right distribution of inward rectifier K(+) currents has been suggested to underlie this dominant frequency gradient, but this hypothesis has never been tested in humans. METHODS AND RESULTS Currents were measured with whole-cell voltage-clamp in cardiomyocytes from right atrial (RA) and left (LA) atrial appendages of patients in sinus rhythm (SR) and patients with AF undergoing cardiac surgery. Western blot was used to quantify protein expression of I(K1) (Kir2.1 and Kir2.3) and I(K,ACh) (Kir3.1 and Kir3.4) subunits. Basal current was ≈2-fold larger in chronic AF (cAF) versus SR patients, without RA-LA differences. In pAF, basal current was ≈2-fold larger in LA versus RA, indicating a left-to-right atrial gradient. In both atria, Kir2.1 expression was ≈2-fold greater in cAF but comparable in pAF versus SR. Kir2.3 levels were unchanged in cAF and RA-pAF but showed a 51% decrease in LA-pAF. In SR, carbachol-activated (2 μmol/L) I(K,ACh) was 70% larger in RA versus LA. This right-to-left atrial gradient was decreased in pAF and cAF caused by reduced I(K,ACh) in RA only. Similarly, in SR, Kir3.1 and Kir3.4 proteins were greater in RA versus LA and decreased in RA of pAF and cAF. Kir3.1 and Kir3.4 expression was unchanged in LA of pAF and cAF. CONCLUSION Our results support the hypothesis that a left-to-right gradient in inward rectifier background current contributes to high-frequency sources in LA that maintain pAF. These findings have potentially important implications for development of atrial-selective therapeutic approaches.
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Affiliation(s)
- Niels Voigt
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
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17
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Astrocyte dysfunction in epilepsy. ACTA ACUST UNITED AC 2010; 63:212-21. [DOI: 10.1016/j.brainresrev.2009.10.004] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Revised: 10/23/2009] [Accepted: 10/27/2009] [Indexed: 12/18/2022]
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Eglen RM, Reisine T. Human kinome drug discovery and the emerging importance of atypical allosteric inhibitors. Expert Opin Drug Discov 2010; 5:277-90. [PMID: 22823023 DOI: 10.1517/17460441003636820] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
IMPORTANCE OF THE FIELD Protein kinases are important targets for drug discovery because they possess critical roles in many human diseases. Several protein kinase inhibitors have entered clinical development with others having already been approved for treating a host of diseases. However, many kinase inhibitors suffer from non-selectivity because they interact with the ATP binding region which has similar structures amongst the protein kinases and this non-selectivity sometimes can cause side effects. As a consequence, there is much interest in developing drugs that inhibit kinases through non-classical mechanisms with the hope of avoiding the side effects of previous kinase drugs. AREAS COVERED IN THIS REVIEW This review covers emerging information on kinase biology and discusses new approaches to design selective inhibitors that do not compete with ATP. WHAT THE READER WILL GAIN The reader will gain a better understanding of the importance of the field of allosteric inhibitor drug discovery and how this has required the adoption of a new generation of high-throughput screening techniques. TAKE HOME MESSAGE Discovery and development of allosteric modulators will result in a family of novel kinase therapies with greater selectivity and more varied ways to control activity of disease causing kinase targets.
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Affiliation(s)
- Richard M Eglen
- Bio-discovery, PerkinElmer Life and Analytical Sciences, 940 Winter St., Waltham, MA, USA +1 781 663 5599 ; +1 781 663 5984 ;
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Ramström C, Chapman H, Viitanen T, Afrasiabi E, Fox H, Kivelä J, Soini S, Korhonen L, Lindholm D, Pasternack M, Törnquist K. Regulation of HERG (KCNH2) potassium channel surface expression by diacylglycerol. Cell Mol Life Sci 2010; 67:157-69. [PMID: 19859662 PMCID: PMC11115617 DOI: 10.1007/s00018-009-0176-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 09/30/2009] [Accepted: 10/06/2009] [Indexed: 01/08/2023]
Abstract
The HERG (KCNH2) channel is a voltage-sensitive potassium channel mainly expressed in cardiac tissue, but has also been identified in other tissues like neuronal and smooth muscle tissue, and in various tumours and tumour cell lines. The function of HERG has been extensively studied, but it is still not clear what mechanisms regulate the surface expression of the channel. In the present report, using human embryonic kidney cells stably expressing HERG, we show that diacylglycerol potently inhibits the HERG current. This is mediated by a protein kinase C-evoked endocytosis of the channel protein, and is dependent on the dynein-dynamin complex. The HERG protein was found to be located only in early endosomes and not lysosomes. Thus, diacylglycerol is an important lipid participating in the regulation of HERG surface expression and function.
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Affiliation(s)
- Cia Ramström
- Department of Biology, Åbo Akademi University, 20520 Turku, Finland
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Hugh Chapman
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Tero Viitanen
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Emad Afrasiabi
- Department of Biology, Åbo Akademi University, 20520 Turku, Finland
| | - Heli Fox
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Johanna Kivelä
- Department of Pharmacology and Clinical Pharmacology, University of Turku, 20520 Turku, Finland
| | - Sanna Soini
- Department of Pharmacology and Clinical Pharmacology, University of Turku, 20520 Turku, Finland
| | - Laura Korhonen
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Dan Lindholm
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Michael Pasternack
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
| | - Kid Törnquist
- Department of Biology, Åbo Akademi University, 20520 Turku, Finland
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki, 00290 Helsinki, Finland
- Department of Biology, Åbo Akademi University, BioCity, Tykistökatu 6, 20520 Turku, Finland
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20
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Blood-brain barrier breakdown-inducing astrocytic transformation: novel targets for the prevention of epilepsy. Epilepsy Res 2009; 85:142-9. [PMID: 19362806 DOI: 10.1016/j.eplepsyres.2009.03.005] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 03/05/2009] [Accepted: 03/08/2009] [Indexed: 01/12/2023]
Abstract
Epileptogenesis is common following brain insults such as trauma, ischemia and infection. However, the mechanisms underlying injury-related epileptogenesis remain unknown. Recent studies demonstrated impaired integrity of the blood-brain barrier (BBB) during epileptogenesis. Here we review accumulating experimental evidence supporting the potential involvement of primary BBB lesion in epileptogenesis. Data from animal experiments demonstrate that primary breakdown of the BBB prone animals to develop focal neocortical epilepsy that is followed by neuronal loss and impaired functions. The extravasation of albumin from the circulation into the brain neuropil was found to be sufficient for the induction of epileptogenesis. Albumin binds to transforming growth factor beta receptor 2 (TGFbetaR2) in astrocytes and induces rapid transcriptional modifications, astrocytic transformation and dysfunction. We highlight a novel cascade of events which is initiated by increased BBB permeability, eventually leading to neuronal dysfunction, epilepsy and cell loss. We review potential mechanisms and existing experimental evidence for the important role of astrocytes and the TGFbeta pathway in epileptogenesis. Finally, we review evidence from human clinical data supporting the involvement of BBB lesion in epilepsy. We propose that primary vascular injury, and specifically BBB breakdown and repair, are key elements in altered interactions within the neurovascular unit and thus may serve as new therapeutic targets.
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21
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Katakura Y, Udono M, Katsuki K, Nishide H, Tabira Y, Ikei T, Yamashita M, Fujiki T, Shirahata S. Protein kinase C delta plays a key role in cellular senescence programs of human normal diploid cells. J Biochem 2009; 146:87-93. [PMID: 19279193 DOI: 10.1093/jb/mvp046] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In the present study, we clarified that transforming growth factor beta (TGF-beta) induces cellular senescence in human normal diploid cells, TIG-1, and identified protein kinase Cs (PKCs) as downstream mediators of TGF-beta-induced cellular senescence. Among PKCs, we showed that PKC-delta induced cellular senescence in TIG-1 cells and was activated in replicatively and prematurely senescent TIG-1 cells. The causative role of PKC-delta in cellular senescence programs was demonstrated using a kinase negative PKC-delta and small interfering RNA against PKC-delta. Furthermore, PKC-delta was shown to function in human telomerase reverse transcriptase (hTERT) gene repression. These results indicate that PKC-delta plays a key role in cellular senescence programs, and suggest that the induction of senescence and hTERT repression are coordinately regulated by PKC-delta.
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Affiliation(s)
- Yoshinori Katakura
- Department of Genetic Resources Technology, Kyushu University, Fukuoka, Japan.
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22
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Roepke TA, Qiu J, Bosch MA, Rønnekleiv OK, Kelly MJ. Cross-talk between membrane-initiated and nuclear-initiated oestrogen signalling in the hypothalamus. J Neuroendocrinol 2009; 21:263-70. [PMID: 19187465 PMCID: PMC2796511 DOI: 10.1111/j.1365-2826.2009.01846.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
It is increasingly evident that 17beta-oestradiol (E(2)), via a distinct membrane oestrogen receptor (Gq-mER), can rapidly activate kinase pathways to have multiple downstream actions in central nervous system (CNS) neurones. We have found that E(2) can rapidly reduce the potency of the GABA(B) receptor agonist baclofen and mu-opioid receptor agonist DAMGO to activate G-protein-coupled, inwardly rectifying K(+) (GIRK) channels in hypothalamic neurones, thereby increasing the excitability (firing activity) of pro-opiomelanocortin (POMC) and dopamine neurones. These effects are mimicked by the membrane impermeant E(2)-BSA and a new ligand (STX) that is selective for the Gq-mER that does not bind to ERalpha or ERbeta. Both E(2) and STX are fully efficacious in attenuating the GABA(B) response in ERalpha, ERbeta and GPR 30 knockout mice in an ICI 182 780 reversible manner. These findings are further proof that E(2) signals through a unique plasma membrane ER. We have characterised the coupling of this Gq-mER to a Gq-mediated activation of phospholipase C leading to the up-regulation of protein kinase Cdelta and protein kinase A activity in these neurones, which ultimately alters gene transcription. Finally, as proof of principle, we have found that STX, similar to E(2), reduces food intake and body weight gain in ovariectomised females. STX, presumably via the Gq-mER, also regulates gene expression of a number of relevant targets including cation channels and signalling molecules that are critical for regulating (as a prime example) POMC neuronal excitability. Therefore, E(2) can activate multiple receptor-mediated pathways to modulate excitability and gene transcription in CNS neurones that are critical for controlling homeostasis and motivated behaviors.
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Affiliation(s)
- Troy A. Roepke
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
| | - Jian Qiu
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
| | - Martha A. Bosch
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
| | - Oline K. Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
- Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR 97239
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006
| | - Martin J. Kelly
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
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23
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Eglen RM, Reisine T. The Current Status of Drug Discovery Against the Human Kinome. Assay Drug Dev Technol 2009; 7:22-43. [DOI: 10.1089/adt.2008.164] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Richard M. Eglen
- Bio-discovery, PerkinElmer Life and Analytical Sciences, Waltham, Massachusetts
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Phosphorylation of Fli1 at threonine 312 by protein kinase C delta promotes its interaction with p300/CREB-binding protein-associated factor and subsequent acetylation in response to transforming growth factor beta. Mol Cell Biol 2009; 29:1882-94. [PMID: 19158279 DOI: 10.1128/mcb.01320-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Previous studies have shown that transforming growth factor beta (TGF-beta)-induced collagen gene expression involves acetylation-dependent dissociation from the human alpha2(I) collagen (COL1A2) promoter of the transcriptional repressor Fli1. The goal of this study was to elucidate the regulatory steps preceding the acetylation of Fli1. We first showed that TGF-beta induces Fli1 phosphorylation on a threonine residue(s). The major phosphorylation site was localized to threonine 312 located in the DNA binding domain of Fli1. Using several independent approaches, we demonstrated that Fli1 is directly phosphorylated by protein kinase C delta (PKC delta). Additional experiments showed that in response to TGF-beta, PKC delta is recruited to the collagen promoter to phosphorylate Fli1 and that this step is a prerequisite for the subsequent interaction of Fli1 with p300/CREB-binding protein-associated factor (PCAF) and an acetylation event. The phosphorylation of endogenous Fli1 preceded its acetylation in response to TGF-beta stimulation, and the blockade of PKC delta abrogated both the phosphorylation and acetylation of Fli1 in dermal fibroblasts. Promoter studies showed that a phosphorylation-deficient mutant of Fli1 exhibited an increased inhibitory effect on the COL1A2 gene, which could not be reversed by the forced expression of PCAF or PKC delta. These data strongly suggest that the phosphorylation-acetylation cascade triggered by PKC delta represents the primary mechanism whereby TGF-beta regulates the transcriptional activity of Fli1 in the context of the collagen promoter.
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Dyachenko V, Rueckschloss U, Isenberg G. Modulation of cardiac mechanosensitive ion channels involves superoxide, nitric oxide and peroxynitrite. Cell Calcium 2009; 45:55-64. [DOI: 10.1016/j.ceca.2008.06.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 05/30/2008] [Accepted: 06/03/2008] [Indexed: 12/22/2022]
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Escartin C, Bonvento G. Targeted activation of astrocytes: a potential neuroprotective strategy. Mol Neurobiol 2008; 38:231-41. [PMID: 18931960 DOI: 10.1007/s12035-008-8043-y] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 09/26/2008] [Indexed: 01/07/2023]
Abstract
Astrocytes are involved in many key physiological processes in the brain, including glutamatergic transmission, energy metabolism, and blood flow control. They become reactive in response to pathological situations, a response that involves well-described morphological alterations and less characterized functional changes. The functional consequences of astrocyte reactivity seem to depend on the molecular pathway involved and may result in the enhancement of several neuroprotective and neurotrophic functions. We propose that a selective and controlled activation of astrocytes may switch these highly pleiotropic cells into therapeutic agents to promote neuron survival and recovery. This may represent a potent therapeutic strategy for many brain diseases in which neurons would benefit from an increased support from activated astrocytes.
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Affiliation(s)
- Carole Escartin
- CEA, IB2M, MIRCen, CNRS URA2210, 4, place du General Leclerc, 91401, Orsay, France.
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27
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Wang G, Zeng J, Shen CY, Wang ZQ, Chen SD. Overexpression of Kir2.3 in PC12 cells resists rotenone-induced neurotoxicity associated with PKC signaling pathway. Biochem Biophys Res Commun 2008; 374:204-9. [DOI: 10.1016/j.bbrc.2008.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 07/01/2008] [Indexed: 12/23/2022]
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Zacchigna S, Lambrechts D, Carmeliet P. Neurovascular signalling defects in neurodegeneration. Nat Rev Neurosci 2008; 9:169-81. [DOI: 10.1038/nrn2336] [Citation(s) in RCA: 275] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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29
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Roepke TA, Malyala A, Bosch MA, Kelly MJ, Rønnekleiv OK. Estrogen regulation of genes important for K+ channel signaling in the arcuate nucleus. Endocrinology 2007; 148:4937-51. [PMID: 17595223 DOI: 10.1210/en.2007-0605] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Estrogen affects the electrophysiological properties of a number of hypothalamic neurons by modulating K(+) channels via rapid membrane actions and/or changes in gene expression. The interaction between these pathways (membrane vs. transcription) ultimately determines the effects of estrogen on hypothalamic functions. Using suppression subtractive hybridization, we produced a cDNA library of estrogen-regulated, brain-specific guinea pig genes, which included subunits from three prominent K+ channels (KCNQ5, Kir2.4, Kv4.1, and Kvbeta(1)) and signaling molecules that impact channel function including phosphatidylinositol 3-kinase (PI3K), protein kinase Cepsilon (PKCepsilon), cAMP-dependent protein kinase (PKA), A-kinase anchor protein (AKAP), phospholipase C (PLC), and calmodulin. Based on these findings, we dissected the arcuate nucleus from ovariectomized guinea pigs treated with estradiol benzoate (EB) or vehicle and analyzed mRNA expression using quantitative real-time PCR. We found that EB significantly increased the expression of KCNQ5 and Kv4.1 and decreased expression of KCNQ3 and AKAP in the rostral arcuate. In the caudal arcuate, EB increased KCNQ5, Kir2.4, Kv4.1, calmodulin, PKCepsilon, PLCbeta(4), and PI3Kp55gamma expression and decreased Kvbeta(1). The effects of estrogen could be mediated by estrogen receptor-alpha, which we found to be highly expressed in the guinea pig arcuate nucleus and, in particular, proopiomelanocortin neurons. In addition, single-cell RT-PCR analysis revealed that about 50% of proopiomelanocortin and neuropeptide Y neurons expressed KCNQ5, about 40% expressed Kir2.4, and about 60% expressed Kv4.1. Therefore, it is evident that the diverse effects of estrogen on arcuate neurons are mediated in part by regulation of K(+) channel expression, which has the potential to affect profoundly neuronal excitability and homeostatic functions, especially when coupled with the rapid effects of estrogen on K(+) channel function.
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Affiliation(s)
- Troy A Roepke
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
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Gadir N, Jackson DN, Lee E, Foster DA. Defective TGF-beta signaling sensitizes human cancer cells to rapamycin. Oncogene 2007; 27:1055-62. [PMID: 17700525 DOI: 10.1038/sj.onc.1210721] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
mTOR, the mammalian target of rapamycin, is a critical target of survival signals in many human cancers. In the absence of serum, rapamycin induces apoptosis in MDA-MB-231 human breast cancer cells. However, in the presence of serum, rapamycin induces G(1) cell cycle arrest-indicating that a factor(s) in serum suppresses rapamycin-induced apoptosis. We report here that transforming growth factor-beta (TGF-beta) suppresses rapamycin-induced apoptosis in serum-deprived MDA-MB-231 cells in a protein kinase Cdelta (PKCdelta)-dependent manner. Importantly, if TGF-beta signaling or PKCdelta was suppressed, rapamycin induced apoptosis rather than G(1) arrest in the presence of serum. And, if cells were allowed to progress into S phase, rapamycin induced apoptosis in the presence of serum. BT-549 and MDA-MB-468 breast, and SW-480 colon cancer cells have defects in TGF-beta signaling and rapamycin induced apoptosis in these cells in the presence of either serum or TGF-beta. Thus, in the absence of TGF-beta signaling, rapamycin becomes cytotoxic rather than cytostatic. Importantly, this study provides evidence indicating that tumors with defective TGF-beta signaling--common in colon and pancreatic cancers--will be selectively sensitive to rapamycin or other strategies that target mTOR.
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Affiliation(s)
- N Gadir
- Department of Biological Sciences, Hunter College of the City University of New York, New York, NY 10021, USA
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31
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Sun Y, Chen M, Lowentritt BH, Van Zijl PS, Koch KR, Keay S, Simard JM, Chai TC. EGF and HB-EGF modulate inward potassium current in human bladder urothelial cells from normal and interstitial cystitis patients. Am J Physiol Cell Physiol 2006; 292:C106-14. [PMID: 16837648 DOI: 10.1152/ajpcell.00209.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interstitial cystitis (IC) is an idiopathic condition characterized by bladder hyperalgesia. Studies have shown cytokine and purinergic signaling abnormalities in cultured bladder urothelial cells (BUC) from IC patients. We performed single-cell electrophysiological studies in both normal and IC BUC. A strongly inward rectifying potassium current with conductance of the Kir2.1 channel was identified in normal BUC. This current was significantly reduced in IC BUC. Kir2.1 protein and mRNA were detected in both IC and normal BUC. Epidermal growth factor (EGF) caused a dose-dependent decrease in the inward potassium current in normal BUC. EGF is secreted in higher amounts by IC BUC and is known to decrease Kir2.1 conductance by phosphorylation of Kir2.1. Genistein, a nonspecific phosphorylation inhibitor, increased the inward potassium current in IC BUC and blocked the effect of EGF on normal BUC. Treatment of IC BUC with heparin-binding epidermal growth factor-like growth factor (HB-EGF), previously shown to be secreted in lower amounts by IC BUC, significantly increased inward potassium current. These data show that the inward potassium current in BUC can be modulated by EGF and HB-EGF. Changes in BUC membrane potassium conductance caused by altered levels of EGF and HB-EGF may therefore play a role in the pathophysiology of IC.
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Affiliation(s)
- Yan Sun
- Division of Urology, University of Maryland, 22 S. Greene Street, S8D18, Baltimore, MD 21201, USA
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Simard JM, Chen M, Tarasov KV, Bhatta S, Ivanova S, Melnitchenko L, Tsymbalyuk N, West GA, Gerzanich V. Newly expressed SUR1-regulated NC(Ca-ATP) channel mediates cerebral edema after ischemic stroke. Nat Med 2006; 12:433-40. [PMID: 16550187 PMCID: PMC2740734 DOI: 10.1038/nm1390] [Citation(s) in RCA: 313] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Accepted: 01/26/2006] [Indexed: 12/25/2022]
Abstract
Pathological conditions in the central nervous system, including stroke and trauma, are often exacerbated by cerebral edema. We recently identified a nonselective cation channel, the NC(Ca-ATP) channel, in ischemic astrocytes that is regulated by sulfonylurea receptor 1 (SUR1), is opened by depletion of ATP and, when opened, causes cytotoxic edema. Here, we evaluated involvement of this channel in rodent models of stroke. SUR1 protein and mRNA were newly expressed in ischemic neurons, astrocytes and capillaries. Upregulation of SUR1 was linked to activation of the transcription factor Sp1 and was associated with expression of functional NC(Ca-ATP) but not K(ATP) channels. Block of SUR1 with low-dose glibenclamide reduced cerebral edema, infarct volume and mortality by 50%, with the reduction in infarct volume being associated with cortical sparing. Our findings indicate that the NC(Ca-ATP) channel is crucially involved in development of cerebral edema, and that targeting SUR1 may provide a new therapeutic approach to stroke.
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Affiliation(s)
- J Marc Simard
- Department of Neurosurgery, School of Medicine, University of Maryland at Baltimore, 22 South Greene Street, Suite 12SD, Baltimore, Maryland 21201-1595, USA.
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Horstmeyer A, Licht C, Scherr G, Eckes B, Krieg T. Signalling and regulation of collagen I synthesis by ET-1 and TGF-beta1. FEBS J 2006; 272:6297-309. [PMID: 16336267 DOI: 10.1111/j.1742-4658.2005.05016.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Endothelin-1 (ET-1) plays an important role in tissue remodelling and fibrogenesis by inducing synthesis of collagen I via protein kinase C (PKC). ET-1 signals are transduced by two receptor subtypes, the ETA- and ETB-receptors which activate different Galpha proteins. Here, we investigated the expression of both ET-receptor subtypes in human primary dermal fibroblasts and demonstrated that the ETA-receptor is the major ET-receptor subtype expressed. To determine further signalling intermediates, we inhibited Galphai and three phospholipases. Pharmacologic inhibition of Galphai, phosphatidylcholine-phospholipase C (PC-PLC) and phospholipase D (PLD), but not of phospholipase Cbeta, abolished the increase in collagen I by ET-1. Inhibition of all phospholipases revealed similar effects on TGF-beta1 induced collagen I synthesis, demonstrating involvement of PC-PLC and PLD in the signalling pathways elicited by ET-1 and TGF-beta1. ET-1 and TGF-beta1 each stimulated collagen I production and in an additive manner. ET-1 further induced connective tissue growth factor (CTGF), as did TGF-beta1, however, to lower levels. While rapid and sustained CTGF induction was seen following TGF-beta1 treatment, ET-1 increased CTGF in a biphasic manner with lower induction at 3 h and a delayed and higher induction after 5 days of permanent ET-1 treatment. Coincidentally at 5 days of permanent ET-1 stimulation, a switch in ET-receptor subtype expression to the ETB-receptor was observed. We conclude that the signalling pathways induced by ET-1 and TGF-beta1 leading to augmented collagen I production by fibroblasts converge on a similar signalling pathway. Thereby, long-time stimulation by ET-1 resulted in a changed ET-receptor subtype ratio and in a biphasic CTGF induction.
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Qin K, Zhao L, Tang Y, Bhatta S, Simard JM, Zhao RY. Doppel-induced apoptosis and counteraction by cellular prion protein in neuroblastoma and astrocytes. Neuroscience 2006; 141:1375-88. [PMID: 16766127 DOI: 10.1016/j.neuroscience.2006.04.068] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 04/18/2006] [Accepted: 04/19/2006] [Indexed: 01/05/2023]
Abstract
Expression of a prion-like protein, doppel, induces apoptosis-like changes in cerebellar neuronal granule and Purkinje cells of prion-knockout mice and this effect can be rescued by re-introduction of cellular prion. Since most of those studies were done in transgenic mice, in the present study, we have established a murine neuro-2a cell line and the primary rat adult reactive astrocyte model for studying doppel-induced apoptosis and possible prion counteraction. We demonstrate that expression of doppel in neuro-2a cells causes apoptosis, during which DNA fragmentation occurs as visualized by terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling staining and other intracellular changes characteristic of apoptosis are observed in the electron microscope. Using immunoblot analyses, we further demonstrate that doppel expression activates caspase-10 as well as caspase-3, but does not activate caspase-9. Addition of purified doppel to cultures of neuro-2a cells and the primary astrocytes causes similar apoptotic changes. Significantly, apoptosis induced by doppel is enhanced when cellular prion protein is depleted by RNA interference, suggesting a protective effect of cellular prion against doppel-induced apoptosis. The antagonistic interaction between cellular prion and doppel appears to involve direct protein-protein interaction possibly on cell membrane as cellular prion and doppel physically interact with each other and co-localize on cell membranes. Together, our data show that doppel induces apoptosis in neuroblastoma neuro-2a and rat primary astrocytes via a caspase-10 mediated pathway and that this effect is counteracted by cellular prion through direct interaction with doppel possibly on cell membrane.
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Affiliation(s)
- K Qin
- Department of Pathology, University of Maryland School of Medicine, 10 South Pine Street, MSTF 700A, Baltimore, MD 21201, USA
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Schein JC, Wang JKT, Roffler-Tarlov SK. The effect of GIRK2(wv) on neurite growth, protein expression, and viability in the CNS-derived neuronal cell line, CATH.A-differentiated. Neuroscience 2005; 134:21-32. [PMID: 15953684 DOI: 10.1016/j.neuroscience.2005.03.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 02/24/2005] [Accepted: 03/12/2005] [Indexed: 11/18/2022]
Abstract
Death occurs in the homozygous mutant mouse weaver among several classes of neuron in cerebellum and ventral midbrain, because these neurons carry a mutation in the G protein-gated inwardly rectifying potassium channel, Girk2. GIRK2 is expressed in all neuronal types killed by wv in cerebellum and midbrain as well as in neurons elsewhere that suffer lesser consequences. GIRK2(wv) affects neurons postnatally, after proliferation, at the time of final differentiation. To assess the impact of GIRK2(wv) on neuronal development and viability, we introduced cDNA encoding wild-type and mutant channels into a variant of a CNS derived catecholamine cell line (Cath.a) known as Cath.a-differentiated. When cultured in serum-free medium, Cath.a-differentiated cells cease proliferation and undergo morphological differentiation, growing long neurites. Cath.a-differentiated cells do not express endogenous Girk channels. Transfection of GIRK2(wv) resulted in the death of Cath.a-differentiated cells, in a cDNA-concentration dependent manner. The highest concentration of Girk2(wv) cDNA caused loss of about half the cells, the next highest concentration one-third, and the least had no effect on viability. However, even the lowest concentration resulted in disruption of neurite outgrowth and reduced the protein products of co-transfected genes. High concentrations of MK801, which prevent Na(+) influx through the mutant channel, prevented death induced by GIRK2(wv). Cell death and disruption of neurite outgrowth were counteracted in GIRK2(wv)-expressing cells by the presence of an unrelated inwardly rectifying potassium channel, Kir2.3. These results are consistent with wv being a gain-of-function mutation, causing disruption of cellular homeostasis by mechanisms such as increased Na(+) influx and chronic depolarization which may in turn result in an excessive metabolic burden on the cell.
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Affiliation(s)
- J C Schein
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA
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Rossignol TM, Jones SVP. Regulation of a family of inwardly rectifying potassium channels (Kir2) by the m1 muscarinic receptor and the small GTPase Rho. Pflugers Arch 2005; 452:164-74. [PMID: 16328454 DOI: 10.1007/s00424-005-0014-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 10/18/2005] [Indexed: 11/26/2022]
Abstract
Inwardly rectifying potassium channels Kir2.1-Kir2.3 are important regulators of membrane potential and, thus, control cellular excitability. However, little is known about the regulation of these channels. Therefore, we studied the mechanisms mediating the regulation of Kir2.1-Kir2.3 by the G-protein-coupled m1 muscarinic receptor using the whole-cell patch-clamp technique and recombinant expression in the tsA201 mammalian cell line. Stimulation of the m1 muscarinic receptor inhibited all subtypes of inward rectifier tested, Kir2.1-Kir2.3. The inhibition of each channel subtype was reversible and was attenuated by the muscarinic receptor antagonist, atropine. The protein kinase C activator phorbol 12-myristate 13-acetate (PMA) mimicked the effects of m1 receptor activation by inhibiting Kir2.1 currents. However, PMA had no effect on Kir2.2 or Kir2.3. Inclusion of 200-microM guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS) in the patch pipette solution prevented the effects of m1 muscarinic receptor stimulation on all three of the channel subtypes tested, confirming the mediation of the responses by G-proteins. Cotransfection with the activated mutant of the small GTPase Rho reduced current density, while C3 exoenzyme, a selective inhibitor of Rho, attenuated the m1 muscarinic receptor-induced inhibition of Kir2.1-Kir2.3. Also, buffering the intracellular calcium concentration with a high concentration of EGTA abolished the m1 receptor-induced inhibition of Kir2.1-Kir2.3, implicating a role for calcium in these responses. These results indicate that all three of the Kir2 channels are similarly inhibited by m1 muscarinic receptor stimulation through calcium-dependent activation of the small GTPase Rho.
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Affiliation(s)
- Todd M Rossignol
- Department of Psychiatry, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Jinnin M, Ihn H, Yamane K, Mimura Y, Asano Y, Tamaki K. Alpha2(I) collagen gene regulation by protein kinase C signaling in human dermal fibroblasts. Nucleic Acids Res 2005; 33:1337-51. [PMID: 15741186 PMCID: PMC552962 DOI: 10.1093/nar/gki275] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We investigated the mechanisms by which protein kinase C (PKC) regulates the expression of the α2(I) collagen gene in normal dermal fibroblasts. Reduction of PKC-α activity by treatment with Gö697-6 or by overexpression of a dominant negative (DN) mutant form decreased α2(I) collagen gene expression. This decrease required a sequence element in the collagen promoter that contains Sp1/Sp3 binding sites. Reduction of PKC-δ activity by rottlerin or overexpression of DN PKC-δ also decreased α2(I) collagen gene expression. This effect required a separate sequence element containing Sp1/Sp3-binding sites and an Ets-binding site. In both cases, point mutations within the response elements abrogated the response to PKC inhibition. Forced overexpression of Sp1 rescued the PKC inhibitor-mediated reduction in collagen protein expression. A DNA affinity precipitation assay revealed that inhibition of PKC-δ by rottlerin increased the binding activity of endogenous Fli1 and decreased that of Ets1. On the other hand, TGF-β1, which increased the expression of PKC-δ, had the opposite effect, increasing the binding activity of Ets1 and decreasing that of Fli1. Our results suggest that PKC-δ is involved in the regulation of the α2(I) collagen gene in the presence or absence of TGF-β. Alteration of the balance of Ets1 and Fli1 may be a novel mechanism regulating α2(I) collagen expression.
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Affiliation(s)
| | - Hironobu Ihn
- To whom correspondence should be addressed. Tel: +81 3 3815 5411; Fax: +81 3 3814 1503;
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Sousa VDO, Romão L, Neto VM, Gomes FCA. Glial fibrillary acidic protein gene promoter is differently modulated by transforming growth factor-beta 1 in astrocytes from distinct brain regions. Eur J Neurosci 2004; 19:1721-30. [PMID: 15078546 DOI: 10.1111/j.1460-9568.2004.03249.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The expression of glial fibrillary acidic protein (GFAP), the major intermediate filament protein of mature astrocytes, is regulated under developmental and pathological conditions. Recently, we have investigated GFAP gene modulation by using a transgenic mouse bearing part of the GFAP gene promoter linked to the beta-galactosidase reporter gene. We demonstrated that cerebral cortex neurons activate the GFAP gene promoter, inducing transforming growth factor-beta 1 (TGF-beta 1) secretion by astrocytes. Here, we report that cortical neurons or conditioned medium derived from them do not activate the GFAP gene promoter of transgenic astrocytes derived from midbrain and cerebellum suggesting a neuroanatomical regional specificity of this phenomenon. Surprisingly, they do induce synthesis of TGF-beta 1 by these cells. Western blot and immunocytochemistry assays revealed wild distribution of TGF receptor in all subpopulations of astrocytes and expression of TGF-beta 1 in neurons derived from all regions, thus indicating that the unresponsiveness of the cerebellar and midbrain GFAP gene to TGF-beta 1 is not due to a defect in TGF-beta 1 signalling. Together, our data highlight the great complexity of neuron-glia interactions and might suggest a distinct mechanism underlying modulation of the GFAP gene in the heterogeneous population of astrocytes throughout the central nervous system.
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Affiliation(s)
- Vivian de Oliveira Sousa
- Departamento de Anatomia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Bloco F, Ilha do Fundão, 21941-590, Rio de Janeiro, RJ, Brazil
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Du X, Zhang H, Lopes C, Mirshahi T, Rohacs T, Logothetis DE. Characteristic interactions with phosphatidylinositol 4,5-bisphosphate determine regulation of kir channels by diverse modulators. J Biol Chem 2004; 279:37271-81. [PMID: 15155739 DOI: 10.1074/jbc.m403413200] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The activity of specific inwardly rectifying potassium (Kir) channels is regulated by any of a number of different modulators, such as protein kinase C, G(q) -coupled receptor stimulation, pH, intracellular Mg(2+) or the betagamma-subunits of G proteins. Phosphatidylinositol 4,5-bisphosphate (PIP(2)) is an essential factor for maintenance of the activity of all Kir channels. Here, we demonstrate that the strength of channel-PIP(2) interactions determines the sensitivity of Kir channels to regulation by the various modulators. Furthermore, our results suggest that differences among Kir channels in their specific regulation by a given modulator may reflect differences in their apparent affinity of interactions with PIP(2).
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Affiliation(s)
- Xiaona Du
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
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40
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Rama Rao KV, Chen M, Simard JM, Norenberg MD. Increased aquaporin-4 expression in ammonia-treated cultured astrocytes. Neuroreport 2004; 14:2379-82. [PMID: 14663195 DOI: 10.1097/00001756-200312190-00018] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Brain edema is a serious complication of hepatic encephalopathy associated with fulminant hepatic failure (FHF). Factors responsible for such swelling are not clear, but ammonia, a toxin strongly implicated in FHF, is known to induce astrocyte swelling. The mechanism(s) responsible for ammonia-induced swelling, however, are not known. Aquaporins are plasma membrane proteins that mediate transmembrane water movement. To investigate the potential role of aquaporins in astrocyte swelling, we measured aquaporin-4 (AQP-4) protein expression in cultured astrocytes exposed to 5 mM NH4Cl. AQP-4 levels significantly increased 10 h after treatment with ammonia, and displayed a progressive rise up to 48 h, which appeared to precede the onset of astrocyte swelling. AQP-4 may be involved in the astrocyte swelling associated with hyperammonemic states.
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Affiliation(s)
- K V Rama Rao
- Department of Pathology, University of Miami School of Medicine, FL 33101, USA
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Rama Rao KV, Chen M, Simard JM, Norenberg MD. Suppression of ammonia-induced astrocyte swelling by cyclosporin A. J Neurosci Res 2004; 74:891-7. [PMID: 14648594 DOI: 10.1002/jnr.10755] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Brain edema is a serious complication of hepatic encephalopathy associated with fulminant hepatic failure (FHF). A major component of the edema seems to be cytotoxic, involving astrocyte swelling. Although the mechanism of brain edema in FHF is incompletely understood, it is generally believed that ammonia is involved critically in this process. Recent studies have shown that exposure of cultured astrocytes to ammonia results in the mitochondrial permeability transition (MPT), a phenomenon associated with mitochondrial failure and subsequent cellular dysfunction. The present study examined the potential role of the MPT in the astrocyte swelling associated with ammonia toxicity. Treatment of cultured astrocytes with ammonia (5 mM) caused a time-dependent increase in astrocyte cell volume (swelling), which was completely inhibited by the MPT inhibitor cyclosporin A (CsA). In this study, CsA also inhibited the ammonia-induced aquaporin 4 (AQP4) upregulation, which had been shown previously to be increased in cultured astrocytes by ammonia treatment. These findings suggest that the MPT plays a significant role in the ammonia-induced astrocyte swelling and may contribute to the brain edema associated with FHF.
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Affiliation(s)
- K V Rama Rao
- Department of Pathology, University of Miami School of Medicine and Veterans Affairs Medical Center, Miami, Florida 33101, USA
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Wang DD, Krueger DD, Bordey A. Biophysical properties and ionic signature of neuronal progenitors of the postnatal subventricular zone in situ. J Neurophysiol 2003; 90:2291-302. [PMID: 12801891 DOI: 10.1152/jn.01116.2002] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies have reported the presence of neuronal progenitors in the subventricular zone (SVZ) and rostral migratory stream (RMS) of the postnatal mammalian brain. Although many studies have examined the survival and migration of progenitors after transplantation and the factors influencing their proliferation or differentiation, no information is available on the electrophysiological properties of these progenitors in a near-intact environment. Thus we performed whole cell and cell-attached patch-clamp recordings of progenitors in brain slices containing either the SVZ or the RMS from postnatal day 15 to day 25 mice. Both regions displayed strong immunoreactivity for nestin and neuron-specific class III beta-tubulin, and recorded cells displayed a morphology typical of the neuronal progenitors known to migrate throughout the SVZ and RMS to the olfactory bulb. Recorded progenitors had depolarized zero-current resting potentials (mean more depolarized than -28 mV), very high input resistances (about 4 GOmega), and lacked action potentials. Using the reversal potential of K+ currents through a cell-attached patch a mean resting potential of -59 mV was estimated. Recorded progenitors displayed Ca2+-dependent K+ currents and TEA-sensitive-delayed rectifying K+ (KDR) currents, but lacked inward K+ currents and transient outward K+ currents. KDR currents displayed classical kinetics and were also sensitive to 4-aminopyridine and alpha-dendrotoxin, a blocker of Kv1 channels. Na+ currents were found in about 60% of the SVZ neuronal progenitors. No developmental changes were observed in the passive membrane properties and current profile of neuronal progenitors. Together these data suggest that SVZ neuronal progenitors display passive membrane properties and an ionic signature distinct from that of cultured SVZ neuronal progenitors and mature neurons.
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Affiliation(s)
- D D Wang
- Department of Neurosurgery and Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06520-8082, USA
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Runyan CE, Schnaper HW, Poncelet AC. Smad3 and PKCdelta mediate TGF-beta1-induced collagen I expression in human mesangial cells. Am J Physiol Renal Physiol 2003; 285:F413-22. [PMID: 12759229 DOI: 10.1152/ajprenal.00082.2003] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Transforming growth factor (TGF)-beta has been associated with fibrogenesis in clinical studies and animal models. We previously showed that Smad3 promotes COL1A2 gene activation by TGF-beta1 in human mesangial cells. In addition to the Smad pathway, it has been suggested that TGF-beta1 could also activate more classical growth factor signaling. Here, we report that protein kinase C (PKC)delta plays a role in TGF-beta1-stimulated collagen I production. In an in vitro kinase assay, TGF-beta1 treatment specifically increased mesangial cell PKCdelta activity in a time-dependent manner. Translocation to the membrane was detected by immunocytochemistry and immunoblot, suggesting activation of PKCdelta by TGF-beta1. Inhibition of PKCdelta by rottlerin decreased basal and TGF-beta1-stimulated collagen I production, mRNA expression, and COL1A2 promoter activity, whereas blockade of conventional PKCs by Gö 6976 had little or no effect. In a Gal4-LUC assay system, inhibition of PKCdelta abolished TGF-beta1-induced transcriptional activity of Gal4-Smad3 and Gal4-Smad4(266-552). Overexpression of Smad3 or Smad3D, in which the three COOH-terminal serine phosphoacceptor residues have been mutated, increased activity of the SBE-LUC construct, containing four DNA binding sites for Smad3 and Smad4. This induction was blocked by PKCdelta inhibition, suggesting that rottlerin decreased Smad3 transcriptional activity independently of COOH-terminal serine phosphorylation. Blockade of PKCdelta abolished ligand-independent and ligand-dependent stimulation of COL1A2 promoter activity by Smad3. These data indicate that PKCdelta is activated by TGF-beta1 in human mesangial cells. TGF-beta1-stimulated PKCdelta activity positively regulates Smad transcriptional activity and is required for COL1A2 gene transcription. Thus cross talk among multiple signaling pathways likely contributes to the pathogenesis of glomerular matrix accumulation.
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Li G, Kim YJ, Mantel C, Broxmeyer HE. P-selectin enhances generation of CD14+CD16+ dendritic-like cells and inhibits macrophage maturation from human peripheral blood monocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:669-77. [PMID: 12847232 DOI: 10.4049/jimmunol.171.2.669] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Endothelial cells play a critical role in monocyte differentiation. Platelets also affect terminal maturation of monocytes in vitro. P-selectin is an important adhesion molecule expressed on both endothelial cells and activated platelets. We investigated its effects on human peripheral blood monocyte differentiation under the influence of different cytokines. Generation of dendritic-like cells (DLCs) from peripheral blood monocytes was promoted by immobilized P-selectin in the presence of M-CSF and IL-4 as judged by dendritic cell (DC) morphology; increased expression of CD1a, a DC marker; low phagocytic activity; and high alloreactivity to naive T cells. In contrast to typical DCs, DLCs expressed CD14 and FcgammaRIII (CD16). These features link the possible identity of DLCs to that of an uncommon CD14(+)CD16(+)CD64(-) monocyte subset found to be expanded in a variety of pathological conditions. Functionally, DLCs generated by P-selectin in combination with M-CSF plus IL-4 primed naive allogeneic CD4(+) T cells to produce significantly less IFN-gamma than cells generated by BSA in the presence of M-CSF and IL-4. P-selectin effects on enhancing CD14(+)CD16(+) DLC generation were completely abrogated by pretreatment of cells with the protein kinase C delta inhibitor rottlerin, but not by classical protein kinase C inhibitor Gö6976. Immobilized P-selectin also inhibited macrophage differentiation in response to M-CSF alone as demonstrated by morphology, phenotype, and phagocytosis analysis. The effects of P-selectin on macrophage differentiation were neutralized by pretreatment of monocytes with Ab against P-selectin glycoprotein ligand 1. These results suggest a novel role for P-selectin in regulating monocyte fate determination.
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Affiliation(s)
- Geling Li
- Department of Microbiology and Immunology, Walther Oncology Center, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Dalton S, Gerzanich V, Chen M, Dong Y, Shuba Y, Simard JM. Chlorotoxin-sensitive Ca2+-activated Cl- channel in type R2 reactive astrocytes from adult rat brain. Glia 2003; 42:325-39. [PMID: 12730953 DOI: 10.1002/glia.10212] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Astrocytes express four types of Cl(-) or anion channels, but Ca(2+)-activated Cl(-) (Cl(Ca)) channels have not been described. We studied Cl(-) channels in a morphologically distinct subpopulation ( approximately 5% of cells) of small (10-12 micro m, 11.8 +/- 0.6 pF), phase-dark, GFAP-positive native reactive astrocytes (NRAs) freshly isolated from injured adult rat brains. Their resting potential, -57.1 +/- 4.0 mV, polarized to -72.7 +/- 4.5 mV with BAPTA-AM, an intracellular Ca(2+) chelator, and depolarized to -30.7 +/- 6.1 mV with thapsigargin, which mobilizes Ca(2+) from intracellular stores. With nystatin-perforated patch clamp, thapsigargin activated a current that reversed near the Cl(-) reversal potential, which was blocked by Cl(-) channel blockers, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and Zn(2+), by I(-) (10 mM), and by chlorotoxin (EC(50) = 47 nM). With conventional whole-cell clamp, NPPB- and Zn(2+)-sensitive currents became larger with increasing [Ca(2+)](i) (10, 150, 300 nM). Single-channel recordings of inside-out patches confirmed Ca(2+) sensitivity of the channel and showed open-state conductances of 40, 80, 130, and 180 pS, and outside-out patches confirmed sensitivity to chlorotoxin. In primary culture, small phase-dark NRAs developed into small GFAP-positive bipolar cells with chlorotoxin-sensitive Cl(Ca) channels. Imaging with biotinylated chlorotoxin confirmed the presence of label in GFAP-positive cells from regions of brain injury, but not from uninjured brain. Chlorotoxin-tagged cells isolated by flow cytometry and cultured up to two passages exhibit positive labeling for GFAP and vimentin, but not for prolyl 4-hydroxylase (fibroblast), A2B5 (O2A progenitor), or OX-42 (microglia). Expression of a novel chlorotoxin-sensitive Cl(Ca) channel in a morphologically distinct subpopulation of NRAs distinguishes these cells as a new subtype of reactive astrocyte.
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Affiliation(s)
- Stanislava Dalton
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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de Sampaio e Spohr TCL, Martinez R, da Silva EF, Neto VM, Gomes FCA. Neuro-glia interaction effects on GFAP gene: a novel role for transforming growth factor-beta1. Eur J Neurosci 2002; 16:2059-69. [PMID: 12473073 DOI: 10.1046/j.1460-9568.2002.02283.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Central nervous system (CNS) development is highly guided by microenvironment cues specially provided by neuron-glia interactions. By using a transgenic mouse bearing part of the gene promoter of the astrocytic maturation marker GFAP (glial fibrillary acidic protein) linked to the beta-galactosidase (beta-Gal) reporter gene, we previously demonstrated that cerebral cortical neurons increase transgenic beta-Gal astrocyte number and activate GFAP gene promoter by secretion of soluble factors in vitro. Here, we identified TGF-beta1 as the major mediator of this event. Identification of TGF-beta1 in neuronal and astrocyte extracts revealed that both cell types might synthesize this factor, however, addition of neurons to astrocyte monolayers greatly increased TGF-beta1 synthesis and secretion by astrocytes. Further, by exploiting the advantages of cell culture system we investigated the influence of neuron and astrocyte developmental stage on such interaction. We demonstrated that younger neurons derived from 14 embryonic days wild-type mice were more efficient in promoting astrocyte differentiation than those derived from 18 embryonic days mice. Similarly, astrocytes also exhibited timed-schedule developed responsiveness to neuronal influence with embryonic astrocytes being more responsive to neurons than newborn and late postnatal astrocytes. RT-PCR assays identified TGF-beta1 transcripts in young but not in old neurons, suggesting that inability to induce astrocyte differentiation is related to TGF-beta1 synthesis and secretion. Our work reveals an important role for neuron-glia interactions in astrocyte development and strongly implicates the involvement of TGF-beta1 in this event.
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Romero-Avila MT, Flores-Jasso CF, García-Sáinz JA. alpha1B-Adrenergic receptor phosphorylation and desensitization induced by transforming growth factor-beta. Biochem J 2002; 368:581-7. [PMID: 12234252 PMCID: PMC1223020 DOI: 10.1042/bj20021052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2002] [Revised: 09/11/2002] [Accepted: 09/17/2002] [Indexed: 01/11/2023]
Abstract
Transforming growth factor-beta (TGF-beta) induced alpha(1B)-adrenergic receptor phosphorylation in Rat-1 fibroblasts stably expressing these adrenoceptors. This effect of TGF-beta was rapid, reaching a maximum within 30 min and decreasing thereafter, and concentration-dependent (EC(50) 0.3 pM). The phosphoinositide 3-kinase inhibitors wortmannin and LY294002, and the protein kinase C inhibitors staurosporine, Ro 318220 and bisindolylmaleimide, blocked the effect of this growth factor. alpha(1B)-Adrenergic receptor phosphorylation was associated with desensitization, as indicated by a reduction in the adrenergic-mediated production of [(3)H]inositol phosphates. Phosphorylation of alpha(1B)-adrenergic receptors by TGF-beta was also observed in Cos-1 cells transfected with the receptor. Co-transfection of the dominant-negative mutant of the regulatory subunit of phosphoinositide 3-kinase (Deltap85) inhibited the phosphorylation of alpha(1B)-adrenergic receptors induced by TGF-beta. Our results indicate that activation of TGF-beta receptors induces alpha(1B)-adrenergic receptor phosphorylation and desensitization. The data suggest that phosphoinositide 3-kinase and protein kinase C play key roles in this effect of TGF-beta.
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Affiliation(s)
- M Teresa Romero-Avila
- Instituto de Fisiologi;a Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-248, México D.F. 04510
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