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Roqué PJ, Barria A, Zhang X, Hashimoto JG, Costa LG, Guizzetti M. Synaptogenesis by Cholinergic Stimulation of Astrocytes. Neurochem Res 2023; 48:3212-3227. [PMID: 37402036 PMCID: PMC10493036 DOI: 10.1007/s11064-023-03979-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/31/2023] [Accepted: 06/27/2023] [Indexed: 07/05/2023]
Abstract
Astrocytes release numerous factors known to contribute to the process of synaptogenesis, yet knowledge about the signals that control their release is limited. We hypothesized that neuron-derived signals stimulate astrocytes, which respond to neurons through the modulation of astrocyte-released synaptogenic factors. Here we investigate the effect of cholinergic stimulation of astrocytes on synaptogenesis in co-cultured neurons. Using a culture system where primary rat astrocytes and primary rat neurons are first grown separately allowed us to independently manipulate astrocyte cholinergic signaling. Subsequent co-culture of pre-stimulated astrocytes with naïve neurons enabled us to assess how prior stimulation of astrocyte acetylcholine receptors uniquely modulates neuronal synapse formation. Pre-treatment of astrocytes with the acetylcholine receptor agonist carbachol increased the expression of synaptic proteins, the number of pre- and postsynaptic puncta, and the number of functional synapses in hippocampal neurons after 24 h in co-culture. Astrocyte secretion of the synaptogenic protein thrombospondin-1 increased after cholinergic stimulation and inhibition of the receptor for thrombospondins prevented the increase in neuronal synaptic structures. Thus, we identified a novel mechanism of neuron-astrocyte-neuron communication, where neuronal release of acetylcholine stimulates astrocytes to release synaptogenic proteins leading to increased synaptogenesis in neurons. This study provides new insights into the role of neurotransmitter receptors in developing astrocytes and into our understanding of the modulation of astrocyte-induced synaptogenesis.
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Affiliation(s)
- Pamela J Roqué
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Andrés Barria
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Xiaolu Zhang
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, USA
- VA Portland Health Care System, Portland, OR, USA
| | - Joel G Hashimoto
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, USA
- VA Portland Health Care System, Portland, OR, USA
| | - Lucio G Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
- Department of Medicine & Surgery, University of Parma, Parma, Italy
| | - Marina Guizzetti
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, USA.
- VA Portland Health Care System, Portland, OR, USA.
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Roqué PJ, Barria A, Zhang X, Costa LG, Guizzetti M. Synaptogenesis by Cholinergic Stimulation of Astrocytes. RESEARCH SQUARE 2023:rs.3.rs-2566078. [PMID: 36824819 PMCID: PMC9949182 DOI: 10.21203/rs.3.rs-2566078/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Astrocytes release numerous factors known to contribute to the process of synaptogenesis, yet knowledge about the signals that control their release is limited. We hypothesized that neuron-derived signals stimulate astrocytes, which respond by signaling back to neurons through the modulation of astrocyte-released synaptogenic factors. Here we investigate the effect of cholinergic stimulation of astrocytes on synaptogenesis in co-cultured neurons. Using a culture system where primary rat astrocytes and primary rat neurons are first grown separately allowed us to independently manipulate astrocyte cholinergic signaling. Subsequent co-culture of pre-stimulated astrocytes with naïve neurons enabled us to assess how prior stimulation of astrocyte acetylcholine receptors uniquely modulates neuronal synapse formation. Pre-treatment of astrocytes with the acetylcholine receptor agonist carbachol increased the expression of synaptic proteins, the number of pre- and postsynaptic puncta, and the number of functional synapses in hippocampal neurons after 24 hours in co-culture. Astrocyte secretion of the synaptogenic protein thrombospondin-1 increased after cholinergic stimulation and the inhibition of the target receptor for thrombospondins prevented the observed increase in neuronal synaptic structures. Thus, we identified a novel mechanism of neuron-astrocyte-neuron communication, i.e. , neuronal release of acetylcholine stimulates astrocytes to release synaptogenic proteins leading to increased synaptogenesis in neurons. This study provides new insights into the role of neurotransmitter receptors in developing astrocytes and into our understanding of the modulation of astrocyte-induced synaptogenesis.
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3
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Li N, Zhou P, Tang H, He L, Fang X, Zhao J, Wang X, Qi Y, Sun C, Lin Y, Qin F, Yang M, Zhang Z, Liao C, Zheng S, Peng X, Xue T, Zhu Q, Li H, Li Y, Liu L, Huang J, Liu L, Peng C, Kaindl AM, Gecz J, Han D, Liu D, Xu K, Hu H. In-depth analysis reveals complex molecular aetiology in a cohort of idiopathic cerebral palsy. Brain 2021; 145:119-141. [PMID: 34077496 PMCID: PMC8967106 DOI: 10.1093/brain/awab209] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/27/2021] [Accepted: 05/17/2021] [Indexed: 12/02/2022] Open
Abstract
Cerebral palsy is the most prevalent physical disability in children; however, its inherent molecular mechanisms remain unclear. In the present study, we performed in-depth clinical and molecular analysis on 120 idiopathic cerebral palsy families, and identified underlying detrimental genetic variants in 45% of these patients. In addition to germline variants, we found disease-related postzygotic mutations in ∼6.7% of cerebral palsy patients. We found that patients with more severe motor impairments or a comorbidity of intellectual disability had a significantly higher chance of harbouring disease-related variants. By a compilation of 114 known cerebral-palsy-related genes, we identified characteristic features in terms of inheritance and function, from which we proposed a dichotomous classification system according to the expression patterns of these genes and associated cognitive impairments. In two patients with both cerebral palsy and intellectual disability, we revealed that the defective TYW1, a tRNA hypermodification enzyme, caused primary microcephaly and problems in motion and cognition by hindering neuronal proliferation and migration. Furthermore, we developed an algorithm and demonstrated in mouse brains that this malfunctioning hypermodification specifically perturbed the translation of a subset of proteins involved in cell cycling. This finding provided a novel and interesting mechanism for congenital microcephaly. In another cerebral palsy patient with normal intelligence, we identified a mitochondrial enzyme GPAM, the hypomorphic form of which led to hypomyelination of the corticospinal tract in both human and mouse models. In addition, we confirmed that the aberrant Gpam in mice perturbed the lipid metabolism in astrocytes, resulting in suppressed astrocytic proliferation and a shortage of lipid contents supplied for oligodendrocytic myelination. Taken together, our findings elucidate novel aspects of the aetiology of cerebral palsy and provide insights for future therapeutic strategies.
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Affiliation(s)
- Na Li
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Pei Zhou
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Hongmei Tang
- Department of Rehabilitation, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510120, Guangzhou, China
| | - Lu He
- Department of Rehabilitation, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510120, Guangzhou, China
| | - Xiang Fang
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Jinxiang Zhao
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Nantong University, 226001, Nantong, China
| | - Xin Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Nantong University, 226001, Nantong, China
| | - Yifei Qi
- Division of Uterine Vascular Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Chuanbo Sun
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Yunting Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Fengying Qin
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Miaomiao Yang
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Zhan Zhang
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Caihua Liao
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Shuxin Zheng
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Xiaofang Peng
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Ting Xue
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Qianying Zhu
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Hong Li
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Yan Li
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Liru Liu
- Department of Rehabilitation, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510120, Guangzhou, China
| | - Jingyu Huang
- Department of Rehabilitation, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510120, Guangzhou, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Changgeng Peng
- The First Rehabilitation Hospital of Shanghai, Tongji University School of Medicine, 200029, Shanghai, China
| | - Angela M Kaindl
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin, 13353, Berlin, Germany.,Department of Pediatric Neurology, Charité-Universitätsmedizin, 13353, Berlin, Germany.,Center for Chronically Sick Children, Charité-Universitätsmedizin, 13353, Berlin, Germany
| | - Jozef Gecz
- Adelaide Medical School, University of Adelaide, SA5005, Adelaide, Australia
| | - Dingding Han
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China
| | - Dong Liu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Nantong University, 226001, Nantong, China
| | - Kaishou Xu
- Department of Rehabilitation, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510120, Guangzhou, China
| | - Hao Hu
- Laboratory of Medical Systems Biology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China.,Guangdong Provincial Key Laboratory of Research in Structural Birth Defect Disease, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623, Guangzhou, China.,Third Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
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Park YS, Liu Z, Vasamsetti BMK, Cho NJ. The ERK1/2 and mTORC1 Signaling Pathways Are Involved in the Muscarinic Acetylcholine Receptor-Mediated Proliferation of SNU-407 Colon Cancer Cells. J Cell Biochem 2016; 117:2854-2863. [PMID: 27167250 DOI: 10.1002/jcb.25597] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/09/2016] [Indexed: 11/06/2022]
Abstract
Muscarinic acetylcholine receptors (mAChRs) regulate diverse cellular functions, including cell growth and proliferation, via multiple signaling pathways. Previously, we showed that mAChRs stimulate the MEK1/2-ERK1/2-RSK pathway in SNU-407 colon cancer cells and subsequently promote cell proliferation. In this study, we provide evidence that the PI3K-Akt-mTORC1-S6K1 pathway is activated by mAChRs in SNU-407 cells and that this pathway is associated with protein biosynthesis and cell proliferation. When the cells were treated with the cholinergic agonist carbachol, Akt was activated in a dose- and time-dependent fashion. This carbachol effect was almost completely blocked by the PI3K inhibitor LY294002, implying that PI3K is responsible for the Akt activation. S6K1, a major downstream target of mTORC1, was also activated by carbachol in a temporal profile similar to that of the Akt activation. This carbachol-stimulated S6K1 activation was abrogated by LY294002 or the mTORC1 inhibitor rapamycin, supporting the notion that mAChRs mediate S6K1 activation via the PI3K-Akt-mTORC1 pathway. We observed that global protein biosynthesis, monitored by puromycin incorporation, was strongly increased by carbachol in an atropine-sensitive manner. Inhibition experiments indicated that the ERK1/2 and mTORC1 signaling pathways may be involved in carbachol-stimulated global protein biosynthesis. We also found that treating SNU-407 cells with LY294002 or rapamycin significantly suppressed carbachol-stimulated cell proliferation. In the presence of the MEK1/2 inhibitor U0126, cell proliferation was further reduced by rapamycin treatment. Our data thus suggest that both the MEK1/2-ERK1/2 and mTORC1 pathways play important roles in mAChR-mediated cell proliferation in SNU-407 colon cancer cells. J. Cell. Biochem. 117: 2854-2863, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Yang-Seo Park
- Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea
| | - Ziyu Liu
- Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea
| | | | - Nam Jeong Cho
- Department of Biochemistry, College of Natural Sciences, Chungbuk National University, Cheongju, 28644, South Korea.
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Wilhelm CJ, Guizzetti M. Fetal Alcohol Spectrum Disorders: An Overview from the Glia Perspective. Front Integr Neurosci 2016; 9:65. [PMID: 26793073 PMCID: PMC4707276 DOI: 10.3389/fnint.2015.00065] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/10/2015] [Indexed: 01/30/2023] Open
Abstract
Alcohol consumption during pregnancy can produce a variety of central nervous system (CNS) abnormalities in the offspring resulting in a broad spectrum of cognitive and behavioral impairments that constitute the most severe and long-lasting effects observed in fetal alcohol spectrum disorders (FASD). Alcohol-induced abnormalities in glial cells have been suspected of contributing to the adverse effects of alcohol on the developing brain for several years, although much research still needs to be done to causally link the effects of alcohol on specific brain structures and behavior to alterations in glial cell development and function. Damage to radial glia due to prenatal alcohol exposure may underlie observations of abnormal neuronal and glial migration in humans with Fetal Alcohol Syndrome (FAS), as well as primate and rodent models of FAS. A reduction in cell number and altered development has been reported for several glial cell types in animal models of FAS. In utero alcohol exposure can cause microencephaly when alcohol exposure occurs during the brain growth spurt a period characterized by rapid astrocyte proliferation and maturation; since astrocytes are the most abundant cells in the brain, microenchephaly may be caused by reduced astrocyte proliferation or survival, as observed in in vitro and in vivo studies. Delayed oligodendrocyte development and increased oligodendrocyte precursor apoptosis has also been reported in experimental models of FASD, which may be linked to altered myelination/white matter integrity found in FASD children. Children with FAS exhibit hypoplasia of the corpus callosum and anterior commissure, two areas requiring guidance from glial cells and proper maturation of oligodendrocytes. Finally, developmental alcohol exposure disrupts microglial function and induces microglial apoptosis; given the role of microglia in synaptic pruning during brain development, the effects of alcohol on microglia may be involved in the abnormal brain plasticity reported in FASD. The consequences of prenatal alcohol exposure on glial cells, including radial glia and other transient glial structures present in the developing brain, astrocytes, oligodendrocytes and their precursors, and microglia contributes to abnormal neuronal development, reduced neuron survival and disrupted brain architecture and connectivity. This review highlights the CNS structural abnormalities caused by in utero alcohol exposure and outlines which abnormalities are likely mediated by alcohol effects on glial cell development and function.
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Affiliation(s)
- Clare J Wilhelm
- Research Service, VA Portland Health Care SystemPortland, OR, USA; Department of Psychiatry, Oregon Health and Science UniversityPortland, OR, USA
| | - Marina Guizzetti
- Research Service, VA Portland Health Care SystemPortland, OR, USA; Department of Behavioral Neuroscience, Oregon Health and Science UniversityPortland, OR, USA
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Kim MJ, Nagy LE, Park PH. Globular adiponectin inhibits ethanol-induced reactive oxygen species production through modulation of NADPH oxidase in macrophages: involvement of liver kinase B1/AMP-activated protein kinase pathway. Mol Pharmacol 2014; 86:284-96. [PMID: 24850909 DOI: 10.1124/mol.114.093039] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Adiponectin, an adipokine predominantly secreted from adipocytes, has been shown to play protective roles against chronic alcohol consumption. Although excessive reactive oxygen species (ROS) production in macrophages is considered one of the critical events for ethanol-induced damage in various target tissues, the effect of adiponectin on ethanol-induced ROS production is not clearly understood. In the present study, we investigated the effect of globular adiponectin (gAcrp) on ethanol-induced ROS production and the potential mechanisms underlying these effects of gAcrp in macrophages. Here we demonstrated that gAcrp prevented ethanol-induced ROS production in both RAW 264.7 macrophages and primary murine peritoneal macrophages. Globular adiponectin also inhibited ethanol-induced activation of NADPH oxidase. In addition, gAcrp suppressed ethanol-induced increase in the expression of NADPH oxidase subunits, including Nox2 and p22(phox), via modulation of nuclear factor-κB pathway. Furthermore, pretreatment with compound C, a selective inhibitor of AMPK, or knockdown of AMPK by small interfering RNA restored suppression of ethanol-induced ROS production and Nox2 expression by gAcrp. Finally, we found that gAcrp treatment induced phosphorylation of liver kinase B1 (LKB1), an upstream signaling molecule mediating AMPK activation. Knockdown of LKB1 restored gAcrp-suppressed Nox2 expression, suggesting that LKB1/AMPK pathway plays a critical role in the suppression of ethanol-induced ROS production and activation of NADPH oxidase by gAcrp. Taken together, these results demonstrate that globular adiponectin prevents ethanol-induced ROS production, at least in part, via modulation of NADPH oxidase in macrophages. Further, LKB1/AMPK axis plays an important role in the suppression of ethanol-induced NADPH oxidase activation by gAcrp in macrophages.
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Affiliation(s)
- Mi Jin Kim
- College of Pharmacy, Yeungnam University, Republic of Korea (M.J.K., P.-H.P.); and Center for Liver Disease Research, Departments of Pathobiology and Gastroenterology, Cleveland Clinic, Cleveland, Ohio (L.E.N.)
| | - Laura E Nagy
- College of Pharmacy, Yeungnam University, Republic of Korea (M.J.K., P.-H.P.); and Center for Liver Disease Research, Departments of Pathobiology and Gastroenterology, Cleveland Clinic, Cleveland, Ohio (L.E.N.)
| | - Pil-Hoon Park
- College of Pharmacy, Yeungnam University, Republic of Korea (M.J.K., P.-H.P.); and Center for Liver Disease Research, Departments of Pathobiology and Gastroenterology, Cleveland Clinic, Cleveland, Ohio (L.E.N.)
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Abkhezr M, Dryer SE. Angiotensin II and canonical transient receptor potential-6 activation stimulate release of a signal transducer and activator of transcription 3-activating factor from mouse podocytes. Mol Pharmacol 2014; 86:150-8. [PMID: 24850910 DOI: 10.1124/mol.114.092536] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Previous studies have shown that the transcription factor signal transducer and activator of transcription-3 (STAT3) in podocytes plays an important role in progression of HIV nephropathy and in collapsing forms of glomerulonephritis. Here, we have observed that application of 100 nM angiotensin II (Ang II) to cultured podocytes for 6-24 hours causes a marked increase in the phosphorylation of STAT3 on tyrosine Y705 but has no effect on phosphorylation at serine S727. By contrast, Ang II treatment of short periods (20-60 minutes) caused a small but consistent suppression of tyrosine phosphylation of STAT3. A similar biphasic effect was seen after treatment with the diacylglycerol analog 1-oleoyl-2-acetyl-sn-glycerol (OAG), an agent that causes activation of Ca(2+)-permeable canonical transient receptor potential-6 (TRPC6) channels in podocytes. The stimulatory effects of Ang II on STAT3 phosphorylation were abolished by small-interfering RNA knockdown of TRPC6 and also by inhibitors of the Ca(2+)-dependent downstream enzymes calcineurin and Ca(2+)-calmodulin-dependent protein kinase II. The stimulatory effects of Ang II appear to be mediated by secretion and accumulation of an unknown factor into the surrounding medium, as they are no longer detected when medium is replaced every 2 hours even if Ang II is continuously present. By contrast, the inhibitory effect of Ang II on STAT3 phosphorylation persists with frequent medium changes. Experiments with neutralizing and inhibitory antibodies suggest that the STAT3 stimulatory factor secreted from podocytes is not interleukin-6, but also suggest that this factor exerts its actions through a receptor system that requires glycoprotein 130.
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Affiliation(s)
- Mousa Abkhezr
- Department of Biology and Biochemistry, University of Houston (M.A., S.E.D.), and Division of Nephrology, Baylor College of Medicine (S.E.D.), Houston, Texas
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston (M.A., S.E.D.), and Division of Nephrology, Baylor College of Medicine (S.E.D.), Houston, Texas
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Abstract
Protein kinase C (PKC) is a family of phospholipid-dependent serine/threonine kinases, which can be further classified into three PKC isozymes subfamilies: conventional or classic, novel or nonclassic, and atypical. PKC isozymes are known to be involved in cell proliferation, survival, invasion, migration, apoptosis, angiogenesis, and drug resistance. Because of their key roles in cell signaling, PKC isozymes also have the potential to be promising therapeutic targets for several diseases, such as cardiovascular diseases, immune and inflammatory diseases, neurological diseases, metabolic disorders, and multiple types of cancer. This review primarily focuses on the activation, mechanism, and function of PKC isozymes during cancer development and progression.
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Guizzetti M, Zhang X, Goeke C, Gavin DP. Glia and neurodevelopment: focus on fetal alcohol spectrum disorders. Front Pediatr 2014; 2:123. [PMID: 25426477 PMCID: PMC4227495 DOI: 10.3389/fped.2014.00123] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 10/24/2014] [Indexed: 12/03/2022] Open
Abstract
During the last 20 years, new and exciting roles for glial cells in brain development have been described. Moreover, several recent studies implicated glial cells in the pathogenesis of neurodevelopmental disorders including Down syndrome, Fragile X syndrome, Rett Syndrome, Autism Spectrum Disorders, and Fetal Alcohol Spectrum Disorders (FASD). Abnormalities in glial cell development and proliferation and increased glial cell apoptosis contribute to the adverse effects of ethanol on the developing brain and it is becoming apparent that the effects of fetal alcohol are due, at least in part, to effects on glial cells affecting their ability to modulate neuronal development and function. The three major classes of glial cells, astrocytes, oligodendrocytes, and microglia as well as their precursors are affected by ethanol during brain development. Alterations in glial cell functions by ethanol dramatically affect neuronal development, survival, and function and ultimately impair the development of the proper brain architecture and connectivity. For instance, ethanol inhibits astrocyte-mediated neuritogenesis and oligodendrocyte development, survival and myelination; furthermore, ethanol induces microglia activation and oxidative stress leading to the exacerbation of ethanol-induced neuronal cell death. This review article describes the most significant recent findings pertaining the effects of ethanol on glial cells and their significance in the pathophysiology of FASD and other neurodevelopmental disorders.
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Affiliation(s)
- Marina Guizzetti
- Department of Psychiatry, University of Illinois at Chicago , Chicago, IL , USA ; Jesse Brown VA Medical Center, U.S. Department of Veterans Affairs , Chicago, IL , USA ; Department of Environmental and Occupational Health Sciences, University of Washington , Seattle, WA , USA
| | - Xiaolu Zhang
- Department of Psychiatry, University of Illinois at Chicago , Chicago, IL , USA ; Jesse Brown VA Medical Center, U.S. Department of Veterans Affairs , Chicago, IL , USA
| | - Calla Goeke
- Department of Psychiatry, University of Illinois at Chicago , Chicago, IL , USA ; Jesse Brown VA Medical Center, U.S. Department of Veterans Affairs , Chicago, IL , USA
| | - David P Gavin
- Department of Psychiatry, University of Illinois at Chicago , Chicago, IL , USA ; Jesse Brown VA Medical Center, U.S. Department of Veterans Affairs , Chicago, IL , USA
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Guizzetti M, Moore NH, VanDeMark KL, Giordano G, Costa LG. Muscarinic receptor-activated signal transduction pathways involved in the neuritogenic effect of astrocytes in hippocampal neurons. Eur J Pharmacol 2011; 659:102-7. [PMID: 21453700 DOI: 10.1016/j.ejphar.2011.03.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 02/22/2011] [Accepted: 03/14/2011] [Indexed: 11/25/2022]
Abstract
Astrocytes have been shown to release factors that affect various aspects of neuronal development. We have previously shown that the acetylcholine analog carbachol, by activating muscarinic M(3) receptors in rat astrocytes, increases their ability to promote neuritogenesis in hippocampal neurons. This effect was mediated by an increased expression and release by astrocytes of several permissive factors, a most relevant of which was fibronectin. In the present study we investigated the signal transduction pathways involved in these effects of carbachol in astrocytes. Results show that multiple pathways are involved in the effects of carbachol on astrocyte-mediated increases in fibronectin expression and neuritogenesis. These include the phospholipase D pathway, leading to sequential activation of protein kinase C (PKC) ζ, p70S6 kinase and nuclear factor-κB; the phosphoinositide-3 kinase pathway; and the PKC ε pathway leading to activation of mitogen activated protein kinase. These pathways were shown to mediate the effect of carbachol on neurite outgrowth as well as the increased expression of fibronectin, further substantiating the important role of the latter in astrocyte-mediated neuritogenesis. Interference with these signaling pathways would be expected to impair astrocyte-neurons communication leading to impaired neuronal development.
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Affiliation(s)
- Marina Guizzetti
- Dept. of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA
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Guizzetti M, Moore NH, Giordano G, VanDeMark KL, Costa LG. Ethanol inhibits neuritogenesis induced by astrocyte muscarinic receptors. Glia 2010; 58:1395-406. [PMID: 20648635 DOI: 10.1002/glia.21015] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In utero alcohol exposure can lead to fetal alcohol spectrum disorders, characterized by cognitive and behavioral deficits. In vivo and in vitro studies have shown that ethanol alters neuronal development. We have recently shown that stimulation of M(3) muscarinic receptors in astrocytes increases the synthesis and release of fibronectin, laminin, and plasminogen activator inhibitor-1, causing neurite outgrowth in hippocampal neurons. As M(3) muscarinic receptor signaling in astroglial cells is strongly inhibited by ethanol, we hypothesized that ethanol may also inhibit neuritogenesis in hippocampal neurons induced by carbachol-stimulated astrocytes. In the present study, we report that the effect of carbachol-stimulated astrocytes on hippocampal neuron neurite outgrowth was inhibited in a concentration-dependent manner (25-100 mM) by ethanol. This effect was because of the inhibition of the release of fibronectin, laminin, and plasminogen activator inhibitor-1. Similar effects on neuritogenesis and on the release of astrocyte extracellular proteins were observed after the incubation of astrocytes with carbachol in the presence of 1-butanol, another short-chain alcohol, which like ethanol is a competitive substrate for phospholipase D, but not by tert-butanol, its analog that is not a substrate for this enzyme. This study identifies a potential novel mechanism involved in the developmental effects of ethanol mediated by the interaction of ethanol with cell signaling in astrocytes, leading to an impairment in neuron-astrocyte communication.
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Affiliation(s)
- Marina Guizzetti
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA.
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VanDemark KL, Guizzetti M, Giordano G, Costa LG. Ethanol inhibits muscarinic receptor-induced axonal growth in rat hippocampal neurons. Alcohol Clin Exp Res 2009; 33:1945-55. [PMID: 19673741 DOI: 10.1111/j.1530-0277.2009.01032.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND In utero alcohol exposure can lead to fetal alcohol spectrum (FAS) disorders characterized by cognitive and behavioral deficits. In vivo and in vitro studies have shown that ethanol alters neuronal development. One mechanism through which ethanol has been shown to exert its effects is the perturbation of activated signaling cascades. The cholinergic agonist carbachol has been shown to induce axonal outgrowth through intracellular calcium mobilization, protein kinase C (PKC) activation, and ERK1/2 phosphorylation. This study investigated the effect of ethanol on the differentiation of rat hippocampal pyramidal neurons induced by carbachol as a possible mechanism involved in the developmental neurotoxicity of ethanol. METHODS Prenatal rat hippocampal pyramidal neurons were treated with ethanol (50 to 75 mM) in the presence or absence of carbachol for 24 hours. Neurite outgrowth was assessed spectrophotometrically; axonal length was measured in neurons fixed and immunolabeled with the neuron-specific betaIII tubulin antibody; cytotoxicity was analyzed using the thiazolyl blue tetrazolium bromide assay. The effect of ethanol on carbachol-stimulated intracellular calcium mobilization was assessed utilizing the fluorescent calcium probe, Fluo-3AM. The PepTag(R) assay for nonradioactive detection of PKC from Promega was used to measure PKC activity, and ERK1/2 activation was determined by densitometric analysis of Western blots probed for phospo-ERK1/2. RESULTS Ethanol treatment (50 to 75 mM) caused an inhibition of carbachol-induced axonal growth, without affecting neuronal viability. Neuron treatment for 15 minutes with ethanol did not inhibit the carbachol-stimulated rise in intracellular calcium, while inhibiting PKC activity at the highest tested concentration and ERK1/2 phosphorylation at both the concentrations used in this study. On the other hand, neuron treatment for 24 hours with ethanol significantly inhibited carbachol-induced increase in intracellular calcium. CONCLUSIONS Ethanol inhibited carbachol-induced neurite outgrowth by inhibiting PKC and ERK1/2 activation. These effects may be, in part, responsible for some of the cognitive deficits associated with in utero alcohol exposure.
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Affiliation(s)
- Kathryn L VanDemark
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
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13
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Slack BE, Blusztajn JK. Differential regulation of mTOR-dependent S6 phosphorylation by muscarinic acetylcholine receptor subtypes. J Cell Biochem 2008; 104:1818-31. [DOI: 10.1002/jcb.21745] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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14
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Fattori V, Abe SI, Kobayashi K, Costa LG, Tsuji R. Effects of postnatal ethanol exposure on neurotrophic factors and signal transduction pathways in rat brain. J Appl Toxicol 2008; 28:370-6. [PMID: 17685400 DOI: 10.1002/jat.1288] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exposure to ethanol during development induces severe brain damage, resulting in a number of CNS dysfunctions including microencephaly and mental retardation. Potential targets of ethanol-induced neurotoxicity include neurotrophic factors and their signal transduction pathways. In the present study, rat pups were given ethanol at the dose of 5 g kg(-1) via gavage from postnatal day (PND) 5 to 8, and mRNA expression of nerve growth-factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophic factor-3 (NT-3) in the cerebral cortex was examined, with attention to signal transduction, on PND 8. The mRNA level of BDNF was decreased by ethanol while those of NGF or NT-3 were not changed. Brain weights were decreased and the levels of phospho-MAPK, phospho-p70S6K and phospho Akt were decreased while phosphor-PKCzeta and phospho-CREB remained unchanged. These results suggest that BDNF and its related signal pathways involving Akt, MAPK and p70S6K are potential targets of ethanol-induced developmental neurotoxicity.
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Affiliation(s)
- Vittorio Fattori
- Environmental Health Science Laboratory, Sumitomo Chemical Co. Ltd., 3-1-98 Kasugade-Naka, Konohana-Ku, Osaka 554-8558, Japan
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15
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Effects of postnatal ethanol exposure at different developmental phases on neurotrophic factors and phosphorylated proteins on signal transductions in rat brain. Neurotoxicol Teratol 2008; 30:228-36. [DOI: 10.1016/j.ntt.2008.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 01/15/2008] [Accepted: 01/15/2008] [Indexed: 11/22/2022]
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16
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Giordano G, Sanchez-Perez AM, Burgal M, Montoliu C, Costa LG, Felipo V. Chronic exposure to ammonia induces isoform-selective alterations in the intracellular distribution and NMDA receptor-mediated translocation of protein kinase C in cerebellar neurons in culture. J Neurochem 2005; 92:143-57. [PMID: 15606904 DOI: 10.1111/j.1471-4159.2004.02852.x] [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: 11/28/2022]
Abstract
Hyperammonemia is responsible for most neurological alterations in patients with hepatic encephalopathy by mechanisms that remain unclear. Hyperammonemia alters phosphorylation of neuronal protein kinase C (PKC) substrates and impairs NMDA receptor-associated signal transduction. The aim of this work was to analyse the effects of hyperammonemia on the amount and intracellular distribution of PKC isoforms and on translocation of each isoform induced by NMDA receptor activation in cerebellar neurons. Chronic hyperammonemia alters differentially the intracellular distribution of PKC isoforms. The amount of all isoforms (except PKC zeta) was reduced (17-50%) in the particulate fraction. The contents of alpha, beta1, and epsilon isoforms decreased similarly in cytosol (65-78%) and membranes (66-83%), whereas gamma, delta, and theta; isoforms increased in cytosol but decreased in membranes, and zeta isoform increased in membranes and decreased in cytosol. Chronic hyperammonemia also affects differentially NMDA-induced translocation of PKC isoforms. NMDA-induced translocation of PKC alpha and beta is prevented by ammonia, whereas PKC gamma, delta, epsilon, or theta; translocation is not affected. Inhibition of phospholipase C did not affect PKC alpha translocation but reduced significantly PKC gamma translocation, indicating that NMDA-induced translocation of PKC alpha is mediated by Ca2+, whereas PKC gamma translocation is mediated by diacylglycerol. Chronic hyperammonemia reduces Ca+2-mediated but not diacylglycerol-mediated translocation of PKC isoforms induced by NMDA.
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Affiliation(s)
- Gennaro Giordano
- Laboratory of Neurobiology, Fundacion Valenciana de Investigaciones Biomédicas. Valencia, Spain
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17
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Renuka TR, Savitha B, Paulose CS. Muscarinic M1 and M3 receptor binding alterations in pancreas during pancreatic regeneration of young rats. Endocr Res 2005; 31:259-70. [PMID: 16433246 DOI: 10.1080/07435800500406163] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The importance of muscarinic receptors in proliferation of different cell types and in insulin secretion from pancreatic beta cells has been extensively studied. However, the role of pancreatic muscarinic receptors during pancreatic regeneration has not yet been studied. For the first time, the functional status of the muscarinic M1 and M3 receptors in regeneration of the pancreas is investigated here. It is observed that the number and affinity of high-affinity muscarinic M3 receptors increased at the time of regeneration. The low-affinity M3 receptors also showed a similar trend. In the case of muscarinic M1 receptors, the receptor number increased with a decrease in affinity. We also observed an increase in the circulating insulin levels at the time of active regeneration. The in vitro studies confirmed that muscarinic receptors are stimulatory to insulin secretion. Our results suggest that the increased muscarinic M1 and M3 receptor subtypes stimulate insulin secretion and islet cell proliferation during the regeneration of pancreas.
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Affiliation(s)
- T R Renuka
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, 682 022, Kerala, India
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18
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Gerasimovskaya EV, Tucker DA, Weiser-Evans M, Wenzlau JM, Klemm DJ, Banks M, Stenmark KR. Extracellular ATP-induced proliferation of adventitial fibroblasts requires phosphoinositide 3-kinase, Akt, mammalian target of rapamycin, and p70 S6 kinase signaling pathways. J Biol Chem 2004; 280:1838-48. [PMID: 15522879 DOI: 10.1074/jbc.m409466200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Extracellular nucleotides are increasingly recognized as important regulators of growth in a variety of cell types. Recent studies have demonstrated that extracellular ATP is a potent inducer of fibroblast growth acting, at least in part, through an ERK1/2-dependent signaling pathway. However, the contributions of additional signaling pathways to extracellular ATP-mediated cell proliferation have not been defined. By using both pharmacologic and genetic approaches, we found that in addition to ERK1/2, phosphatidylinositol 3-kinase (PI3K), Akt, mammalian target of rapamycin (mTOR), and p70 S6K-dependent signaling pathways are required for ATP-induced proliferation of adventitial fibroblasts. We found that extracellular ATP acting in part through G(i) proteins increased PI3K activity in a time-dependent manner and transient phosphorylation of Akt. This PI3K pathway is not involved in ATP-induced activation of ERK1/2, implying activation of independent parallel signaling pathways by ATP. Extracellular ATP induced dramatic increases in mTOR and p70 S6K phosphorylation. This activation of the mTOR/p70 S6 kinase (p70 S6K) pathway in response to ATP is because of independent contributions of PI3K/Akt and ERK1/2 pathways, which converge on the level of p70 S6K. ATP-dependent activation of mTOR and p70 S6K also requires additional signaling inputs perhaps from pathways operating through Galpha or Gbetagamma subunits. Collectively, our data demonstrate that ATP-induced adventitial fibroblast proliferation requires activation and interaction of multiple signaling pathways such as PI3K, Akt, mTOR, p70 S6K, and ERK1/2 and provide evidence for purinergic regulation of the protein translational pathways related to cell proliferation.
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Affiliation(s)
- Evgenia V Gerasimovskaya
- Developmental Lung Biology Laboratory, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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Smith TL, Eaton MC. Continuous ethanol exposure inhibits agonist-stimulated phosphorylation of p70S6 kinase and ribosomal S6 protein in cultured rat astrocytes. ACTA ACUST UNITED AC 2004; 131:145-8. [PMID: 15530665 DOI: 10.1016/j.molbrainres.2004.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2004] [Indexed: 11/22/2022]
Abstract
The effects of ethanol exposure on agonist-stimulated phosphorylation of p70S6 kinase and ribosomal S6 protein were determined in confluent astrocyte monolayers. Basal phosphorylation of p70S6 kinase and S6 protein was either unaffected or reduced, respectively, after exposure to 50 mM ethanol for 4 days. The abilities of norepinephrine, carbachol and epidermal growth factor to phosphorylate these proteins were significantly decreased after ethanol exposure. In contrast, ethanol exposure had no effect on the protein expression of either p70S6 kinase or S6 protein. Our data suggest that continuous ethanol exposure results in a generalized decrease in agonist-activation of the p70S6 pathway.
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Affiliation(s)
- Thomas L Smith
- Research Health Care Group (0-151), Southern Arizona VA Health Care System, Tucson, AZ, USA.
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20
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Peng CH, Tseng TH, Liu JY, Hsieh YH, Huang CN, Hsu SP, Wang CJ. Penta-acetyl geniposide-induced C6 glioma cell apoptosis was associated with the activation of protein kinase C-delta. Chem Biol Interact 2004; 147:287-96. [PMID: 15135084 DOI: 10.1016/j.cbi.2004.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2004] [Indexed: 12/11/2022]
Abstract
Herbal medicine has been utilized to treat a variety of diseases, including cancer. On the other hand, disturbance of apoptosis is often observed in cancer cells. It has been reported that protein kinase C (PKC) isoforms are involved in the signaling of apoptosis. In the present study, we investigate the antitumor effect and possible mechanism of a herbal-originated product, (Ac)(5)GP. We demonstrate that (Ac)(5)GP treatment results in DNA fragmentation of C6 glioma cells dose-dependently. Stimulated by (Ac)(5)GP, PKCdelta and PKCzeta were activated and translocated to the cell membrane fraction. Flow cytometry analysis showed that PKCdelta, but not PKCzeta inhibition blocks the (Ac)(5)GP-induced apoptosis by decreasing the cell population of sub G1 peak. However, the mRNA levels of PKCdelta and PKCzeta were not altered by (Ac)(5)GP-induced glioma cell apoptosis. These results suggested that the treatment of (Ac)(5)GP induces apoptosis of tumor cells through the activation but not the synthesis of PKCdelta.
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Affiliation(s)
- Chiung-Huei Peng
- Institute of Biochemistry, Chung Shan Medical University, No. 110, Section 2, Chien Kuo N. Road, Taichung 402, Taichung, Taiwan, ROC
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22
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Perry C, Sklan EH, Soreq H. CREB regulates AChE-R-induced proliferation of human glioblastoma cells. Neoplasia 2004; 6:279-86. [PMID: 15153340 PMCID: PMC1502102 DOI: 10.1593/neo.3424] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Revised: 12/09/2003] [Accepted: 12/11/2003] [Indexed: 11/18/2022]
Abstract
The cyclic adenosine monophosphate (AMP) response element-binding protein, CREB, often modulates stress responses. Here, we report that CREB suppresses the glioblastoma proliferative effect of the stress-induced acetylcholinesterase variant, AChE-R. In human U87MG glioblastoma cells, AChE-R formed a triple complex with protein kinase C (PKC) epsilon and the scaffold protein RACK1, enhanced PKCepsilon phosphorylation, and facilitated BrdU incorporation. Either overexpressed CREB, or antisense destruction of AChE-R mRNA, PKC, or protein kinase A (PKA) inhibitors-but not CREB combined with PKC inhibition suppressed-this proliferation, suggesting that CREB's repression of this process involves a PKC-mediated pathway, whereas impaired CREB regulation allows AChE-R-induced, PKA-mediated proliferation of glioblastoma tumors.
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Affiliation(s)
- Chava Perry
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- Department of Hematology, The Tel-Aviv Sourasky Medical Center-Tel Aviv and Tel-Aviv University, Tel-Aviv 64239, Israel
| | - Ella H Sklan
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Hermona Soreq
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Guizzetti M, Bordi F, Dieguez-Acuña FJ, Vitalone A, Madia F, Woods JS, Costa LG. Nuclear factor kappaB activation by muscarinic receptors in astroglial cells: effect of ethanol. Neuroscience 2003; 120:941-50. [PMID: 12927200 DOI: 10.1016/s0306-4522(03)00401-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Activation of muscarinic receptors leads to proliferation of astroglial cells and this effect is inhibited by ethanol. Among the intracellular pathways involved in the mitogenic action of muscarinic agonists, activation of the atypical protein kinase C zeta (PKC zeta) appears to be of most importance, and is also affected by low ethanol concentrations. PKC zeta has been reported to activate nuclear factor kappaB (NF-kappaB), a transcription factor that has been shown to play an important role in cell proliferation. The aim of this study was, therefore, to determine whether muscarinic receptors would activate NF-kappaB in astroglial cells, whether such activation would play a role in the mitogenic action of muscarinic agonists, and whether it would represent a possible target for ethanol. Carbachol activated NF-kappaB in human 1321N1 astrocytoma cells, as evidenced by translocation of the p65 subunit of NF-kappaB to the nucleus, phosphorylation and degradation of IkappaBalpha in the cytosol, and increase NF-kappaB binding to DNA. Carbachol also induced translocation of p65 to the nucleus in primary rat astrocytes. Carbachol-induced NF-kappaB activation was mediated by the M3 subtype of muscarinic receptors and appeared to involve Ca(2+) mobilization and activation of PKC epsilon and PKC zeta, but not PI3-kinase and mitogen-activated protein kinase. The NF-kappaB peptide inhibitor SN50, but not the inactive peptide SN50M, strongly inhibited carbachol-induced astrocytoma cells proliferation and p65 translocation to the nucleus. Increased DNA synthesis was also antagonized by the IkappaBalpha kinase inhibitor BAY 11-7082. Ethanol (25-100 mM) inhibited the translocation of p65 and the binding of NF-kappaB to DNA in both 1321N1 astrocytoma cells and primary rat cortical astrocytes. Together, these results suggest that activation of NF-kappaB by muscarinic receptors in astroglial cells is important for carbachol-induced DNA synthesis and that ethanol-mediated inhibition of cell proliferation may be due in part to inhibition of NF-kappaB activation.
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Affiliation(s)
- M Guizzetti
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way Northeast 100, Seattle, WA 98105, USA.
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Guizzetti M, Möller T, Costa LG. Ethanol inhibits muscarinic receptor-mediated DNA synthesis and signal transduction in human fetal astrocytes. Neurosci Lett 2003; 344:68-70. [PMID: 12781924 DOI: 10.1016/s0304-3940(03)00431-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We previously found that ethanol inhibits muscarinic receptor-induced proliferation of rat cortical astrocytes and human astrocytoma cells and suggested this as a possible mechanism involved in its developmental neurotoxicity. We also observed that, though several signal transduction pathways are relevant for carbachol-induced cell proliferation, activation of PKC zeta and p70S6 kinase is selectively inhibited by low concentrations of ethanol. In the present study we used fetal human astrocytes to expand these findings to a direct target of ethanol in humans. Astrocyte cultures, deriving from legally aborted fetuses, were stained for GFAP and shown to be 90-95% pure. Carbachol induced increases in [(3)H]thymidine and BrdU incorporation in synchronized cells. Carbachol-induced DNA synthesis was strongly inhibited by ethanol. Carbachol also induced phosphorylation of (Thr410)PKC zeta, (Ser473)Akt, and (Thr389)p70S6 kinase, and ethanol (50 mM) inhibited phosphorylation of PKC zeta and p70S6 kinase, but not of Akt. These results expand previous findings in rat astrocytes and human astrocytoma cells and suggest that intracellular signal transduction pathways activated by muscarinic receptors may represent a relevant target for the developmental neurotoxicity of ethanol in humans.
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Affiliation(s)
- Marina Guizzetti
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA 98105, USA.
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Smith TL, Navratilova E. The effect of ethanol exposure on mitogen-activated protein kinase activity and expression in cultured rat astrocytes. Neurosci Lett 2003; 341:91-4. [PMID: 12686373 DOI: 10.1016/s0304-3940(03)00179-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effects of ethanol exposures on mitogen-activated protein kinase (MAPK) activity were determined in confluent astrocyte monolayers prepared from neonatal rat cerebral cortex. Acute 30 min exposure to 50 mM ethanol had no significant effect on MAPK activity. However, chronic exposure to ethanol for 4 days elicited a concentration-dependent increase in the basal level of this enzyme activity with no parallel increase in its protein expression. In addition, the magnitude of MAPK activation by epidermal growth factor, basic fibroblast growth factor and platelet-derived growth factor was significantly increased above corresponding control values in cells chronically exposed to ethanol. Immunolabeling experiments indicated that the protein expression of receptors for these growth factors was unaffected by ethanol treatment. Our results suggest that even after chronic ethanol treatment, MAPK phosphorylation and, hence, activation remains elevated.
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Affiliation(s)
- Thomas L Smith
- Research Health Care Group (0-151), Southern AZ VA Health Care System, Tucson, AZ, USA.
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