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Lee CJ, Lee SH, Kang BS, Park MK, Yang HW, Woo SY, Park SW, Kim DY, Jeong HH, Yang WI, Kho AR, Choi BY, Song HK, Choi HC, Kim YJ, Suh SW. Effects of L-Type Voltage-Gated Calcium Channel (LTCC) Inhibition on Hippocampal Neuronal Death after Pilocarpine-Induced Seizure. Antioxidants (Basel) 2024; 13:389. [PMID: 38671837 PMCID: PMC11047745 DOI: 10.3390/antiox13040389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/15/2024] [Accepted: 03/15/2024] [Indexed: 04/28/2024] Open
Abstract
Epilepsy, marked by abnormal and excessive brain neuronal activity, is linked to the activation of L-type voltage-gated calcium channels (LTCCs) in neuronal membranes. LTCCs facilitate the entry of calcium (Ca2+) and other metal ions, such as zinc (Zn2+) and magnesium (Mg2+), into the cytosol. This Ca2+ influx at the presynaptic terminal triggers the release of Zn2+ and glutamate to the postsynaptic terminal. Zn2+ is then transported to the postsynaptic neuron via LTCCs. The resulting Zn2+ accumulation in neurons significantly increases the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, contributing to reactive oxygen species (ROS) generation and neuronal death. Amlodipine (AML), typically used for hypertension and coronary artery disease, works by inhibiting LTCCs. We explored whether AML could mitigate Zn2+ translocation and accumulation in neurons, potentially offering protection against seizure-induced hippocampal neuronal death. We tested this by establishing a rat epilepsy model with pilocarpine and administering AML (10 mg/kg, orally, daily for 7 days) post-epilepsy onset. We assessed cognitive function through behavioral tests and conducted histological analyses for Zn2+ accumulation, oxidative stress, and neuronal death. Our findings show that AML's LTCC inhibition decreased excessive Zn2+ accumulation, reactive oxygen species (ROS) production, and hippocampal neuronal death following seizures. These results suggest amlodipine's potential as a therapeutic agent in seizure management and mitigating seizures' detrimental effects.
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Affiliation(s)
- Chang-Jun Lee
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Song-Hee Lee
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Beom-Seok Kang
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Min-Kyu Park
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Hyun-Wook Yang
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Seo-Young Woo
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Se-Wan Park
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Dong-Yeon Kim
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Hyun-Ho Jeong
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
| | - Won-Il Yang
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
- Department of Physical Education, Hallym University, Chuncheon 24252, Republic of Korea;
| | - A-Ra Kho
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Bo-Young Choi
- Department of Physical Education, Hallym University, Chuncheon 24252, Republic of Korea;
| | - Hong-Ki Song
- Department of Neurology, Kangdong Sacred Heart Hospital, Seoul 05355, Republic of Korea; (H.-K.S.); (Y.-J.K.)
- Hallym Institute of Epilepsy Research, Chuncheon 24252, Republic of Korea;
| | - Hui-Chul Choi
- Hallym Institute of Epilepsy Research, Chuncheon 24252, Republic of Korea;
- Department of Neurology, Hallym University Chuncheon Sacred Heart Hospital, Chuncheon 24253, Republic of Korea
| | - Yeo-Jin Kim
- Department of Neurology, Kangdong Sacred Heart Hospital, Seoul 05355, Republic of Korea; (H.-K.S.); (Y.-J.K.)
| | - Sang-Won Suh
- Department of Physiology, Hallym University College of Medicine, Chuncheon 24252, Republic of Korea; (C.-J.L.); (S.-H.L.); (B.-S.K.); (M.-K.P.); (H.-W.Y.); (S.-Y.W.); (S.-W.P.); (D.-Y.K.); (H.-H.J.); (W.-I.Y.)
- Hallym Institute of Epilepsy Research, Chuncheon 24252, Republic of Korea;
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Schartz ND, Herr SA, Madsen L, Butts SJ, Torres C, Mendez LB, Brewster AL. Spatiotemporal profile of Map2 and microglial changes in the hippocampal CA1 region following pilocarpine-induced status epilepticus. Sci Rep 2016; 6:24988. [PMID: 27143585 PMCID: PMC4855223 DOI: 10.1038/srep24988] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 04/06/2016] [Indexed: 01/01/2023] Open
Abstract
Status epilepticus (SE) triggers pathological changes to hippocampal dendrites that may promote epileptogenesis. The microtubule associated protein 2 (Map2) helps stabilize microtubules of the dendritic cytoskeleton. Recently, we reported a substantial decline in Map2 that coincided with robust microglia accumulation in the CA1 hippocampal region after an episode of SE. A spatial correlation between Map2 loss and reactive microglia was also reported in human cortex from refractory epilepsy. New evidence supports that microglia modulate dendritic structures. Thus, to identify a potential association between SE-induced Map2 and microglial changes, a spatiotemporal profile of these events is necessary. We used immunohistochemistry to determine the distribution of Map2 and the microglia marker IBA1 in the hippocampus after pilocarpine-induced SE from 4 hrs to 35 days. We found a decline in Map2 immunoreactivity in the CA1 area that reached minimal levels at 14 days post-SE and partially increased thereafter. In contrast, maximal microglia accumulation occurred in the CA1 area at 14 days post-SE. Our data indicate that SE-induced Map2 and microglial changes parallel each other’s spatiotemporal profiles. These findings may lay the foundation for future mechanistic studies to help identify potential roles for microglia in the dendritic pathology associated with SE and epilepsy.
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Affiliation(s)
- Nicole D Schartz
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Seth A Herr
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Lauren Madsen
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Sarah J Butts
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Ceidy Torres
- School of Science and Technology, Universidad del Este, Carolina, PR 00984, Puerto Rico
| | - Loyda B Mendez
- School of Science and Technology, Universidad del Este, Carolina, PR 00984, Puerto Rico
| | - Amy L Brewster
- Department of Psychological Sciences, West Lafayette, IN 47907, USA.,Weldon School of Biomedical Engineering, West Lafayette, IN 47907, USA
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Wu XM, Wang GL, Miao J, Feng JC. Effect of connexin 36 blockers on the neuronal cytoskeleton and synaptic plasticity in kainic acid-kindled rats. Transl Neurosci 2015; 6:252-258. [PMID: 28123810 PMCID: PMC4936636 DOI: 10.1515/tnsci-2015-0027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/17/2015] [Indexed: 12/11/2022] Open
Abstract
In this study we investigated the potential anti-epileptogenic effect of neuronal connexin Cx36 gap junction blockage via inhibition of microtubule-associated protein 2 (MAP-2) and synaptophysin (SYP) overexpression. Thirty adult male Wistar rats were divided into five groups (six animals per group): control, sham, carbenoxolone (CBX), quinine (QN), and quinidine (QND). An epilepsy model was produced by injecting kainic acid (KA) into the rat amygdala. Broad-spectrum and selective blockers of the Cx36 channel (CBX, QN, and QND) were administered via intraperitoneal injection. Expression of MAP-2 and SYP was assessed by immunofluorescent and immunohistochemical examination. Expression of MAP-2 and SYP was significantly increased after KA administration in the sham group compared with the control group. Expression of MAP-2 and SYP was significantly decreased in the CBX, QN, and QND groups compared with the sham group. The results provide new evidence regarding the key role of MAP-2 and SYP overexpression in three important mechanisms: the modulation of neuronal plasticity, hyperexcitability of the hippocampal neuronal network, and persistent seizure discharge. Furthermore, the reversal of MAP-2 and SYP overexpression following administration of Cx36 channel blockers indicates a potential role for Cx36 channel blockers in anti-epileptogenic treatment and in doing so, highlights a critical need for further investigation of these compounds.
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Affiliation(s)
- Xue-Mei Wu
- Department of Pediatric Neurology, First Hospital of Jilin University, Changchun, P.R. China
| | - Guang-Liang Wang
- Department of Cardiology, Peking University International Hospital, Peking, P.R. China
| | - Jing Miao
- Department of Neurology, First Hospital of Jilin University, Changchun, P.R. China
| | - Jia-Chun Feng
- Department of Neurology, First Hospital of Jilin University, Changchun, P.R. China
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López-Menéndez C, Gamir-Morralla A, Jurado-Arjona J, Higuero AM, Campanero MR, Ferrer I, Hernández F, Ávila J, Díaz-Guerra M, Iglesias T. Kidins220 accumulates with tau in human Alzheimer's disease and related models: modulation of its calpain-processing by GSK3β/PP1 imbalance. Hum Mol Genet 2012; 22:466-82. [PMID: 23118350 DOI: 10.1093/hmg/dds446] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Failures in neurotrophic support and signalling play key roles in Alzheimer's disease (AD) pathogenesis. We previously demonstrated that downregulation of the neurotrophin effector Kinase D interacting substrate (Kidins220) by excitotoxicity and cerebral ischaemia contributed to neuronal death. This downregulation, triggered through overactivation of N-methyl-D-aspartate receptors (NMDARs), involved proteolysis of Kidins220 by calpain and transcriptional inhibition. As excitotoxicity is at the basis of AD aetiology, we hypothesized that Kidins220 might also be downregulated in this disease. Unexpectedly, Kidins220 is augmented in necropsies from AD patients where it accumulates with hyperphosphorylated tau. This increase correlates with enhanced Kidins220 resistance to calpain processing but no higher gene transcription. Using AD brain necropsies, glycogen synthase kinase 3-β (GSK3β)-transgenic mice and cell models of AD-related neurodegeneration, we show that GSK3β phosphorylation decreases Kidins220 susceptibility to calpain proteolysis, while protein phosphatase 1 (PP1) action has the opposite effect. As altered activities of GSK3β and phosphatases are involved in tau aggregation and constitute hallmarks in AD, a GSK3β/PP1 imbalance may also contribute to Kidins220 decreased clearance, accumulation and hampered neurotrophin signalling from early stages of the disease pathogenesis. These results encourage searches for mutations in Kidins220 gene and their possible associations to dementias. Finally, our data support a model where the effects of excitotoxicity drastically differ when occurring in cerebral ischaemia versus progressively sustained toxicity along AD progression. The striking differences in Kidins220 stability resulting from chronic versus acute brain damage may also have important implications for the therapeutic intervention of neurodegenerative disorders.
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Moraes CF, Lins TC, Carmargos EF, Naves JOS, Pereira RW, Nóbrega OT. Lessons from genome-wide association studies findings in Alzheimer's disease. Psychogeriatrics 2012; 12:62-73. [PMID: 22416831 DOI: 10.1111/j.1479-8301.2011.00378.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder with a complex genetic background. Recent genome-wide association studies (GWAS) have placed important new contributors into the genetic framework of early- and late-onset forms of this dementia. Besides confirming the major role of classic allelic variants (e.g. apolipoprotein E) in the development of AD, GWAS have thus far implicated over 20 single nucleotide polymorphisms in AD. In this review, we summarize the findings of 16 AD-based GWAS performed to date whose public registries are available at the National Human Genome Research Institute, with an emphasis on understanding whether the polymorphic markers under consideration support functional implications to the pathophysiological role of the major genetic risk factors unraveled by GWAS.
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Affiliation(s)
- Clayton F Moraes
- Geriatric Service, Hospital of the Catholic University of Brasília, Graduate Program in Medical Sciences, University of Brasília, Brasília - DF, Brazil
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García-Marín V, Blazquez-Llorca L, Rodriguez JR, Gonzalez-Soriano J, DeFelipe J. Differential distribution of neurons in the gyral white matter of the human cerebral cortex. J Comp Neurol 2011; 518:4740-59. [PMID: 20963826 DOI: 10.1002/cne.22485] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The neurons in the cortical white matter (WM neurons) originate from the first set of postmitotic neurons that migrates from the ventricular zone. In particular, they arise in the subplate that contains the earliest cells generated in the telencephalon, prior to the appearance of neurons in gray matter cortical layers. These cortical WM neurons are very numerous during development, when they are thought to participate in transient synaptic networks, although many of these cells later die, and relatively few cells survive as WM neurons in the adult. We used light and electron microscopy to analyze the distribution and density of WM neurons in various areas of the adult human cerebral cortex. Furthermore, we examined the perisomatic innervation of these neurons and estimated the density of synapses in the white matter. Finally, we examined the distribution and neurochemical nature of interneurons that putatively innervate the somata of WM neurons. From the data obtained, we can draw three main conclusions: first, the density of WM neurons varies depending on the cortical areas; second, calretinin-immunoreactive neurons represent the major subpopulation of GABAergic WM neurons; and, third, the somata of WM neurons are surrounded by both glutamatergic and GABAergic axon terminals, although only symmetric axosomatic synapses were found. By contrast, both symmetric and asymmetric axodendritic synapses were observed in the neuropil. We discuss the possible functional implications of these findings in terms of cortical circuits.
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Affiliation(s)
- V García-Marín
- Laboratorio de Circuitos Corticales, Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, Madrid, Spain.
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Liang Y, Li QF, Zhang XY, Shi SL, Jing GJ. Differential expression of nuclear matrix proteins during the differentiation of human neuroblastoma SK-N-SH cells induced by retinoic acid. J Cell Biochem 2009; 106:849-57. [DOI: 10.1002/jcb.22052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Queiróz DBC, Silva AMD, Gutiérrez-Ospina G, Porto CS, Grossman G, Petrusz P, Avellar MCW. Cells positive for microtubule-associated protein 1B (MAP 1B) are present along rat and human efferent ductules and epididymis. Cell Tissue Res 2006; 325:125-33. [PMID: 16541288 DOI: 10.1007/s00441-005-0108-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2005] [Accepted: 10/21/2005] [Indexed: 11/29/2022]
Abstract
Microtubule-associated protein 1B (MAP 1B) is a neuronal cytoskeleton marker with predominant expression in the developing nervous system. The present study provides evidence for the expression of this cytoskeleton protein in non-neuronal and neuronal cells along rat and human efferent ductules and epididymis (initial segment, caput, and cauda). Reverse transcription/polymerase chain reaction and Western blot analysis were used to confirm the presence of MAP 1B (mRNA and protein) in rat tissues. Immunohistochemical studies revealed MAP-1B-positive staining in columnar ciliated cells present in efferent ductules and in narrow cells located in the initial segment, in both rat and human. MAP-1B-positive basal cells, located underneath the columnar cells, were only identified in the initial segment and caput epididymidis of the rat. Qualitative analysis of tissues from 40-day-old and 120-day-old rats indicated that the number of MAP-1B-positive ciliated, narrow, and basal cells per tubule increased with sexual maturation. These immunoreactive cells did not stain for dopamine beta-hydroxylase or acetylcholinesterase, indicating that they were not adrenergic or cholinergic in nature. Immunohistochemical studies also revealed the presence of MAP-1B-positive staining in interstitial nerve fibers in caput and cauda epididymidis from both rat and human. Thus, the expression of MAP 1B is not confined to a specific cell type in rat and human efferent ductules and epididymis. The functional significance of this cytoskeleton protein in tissues from the male reproductive tract requires further investigation.
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Affiliation(s)
- Daniel B C Queiróz
- Section of Experimental Endocrinology, Department of Pharmacology, Universidade Federal de São Paulo-Escola Paulista de Medicina, Rua 3 de maio 100, INFAR, Vila Clementino, 04044-020 São Paulo, Brazil
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Tseng HC, Ovaa H, Wei NJC, Ploegh H, Tsai LH. Phosphoproteomic analysis with a solid-phase capture-release-tag approach. ACTA ACUST UNITED AC 2005; 12:769-77. [PMID: 16039524 DOI: 10.1016/j.chembiol.2005.05.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 04/28/2005] [Accepted: 05/03/2005] [Indexed: 11/16/2022]
Abstract
A comprehensive study of global phosphorylation events in biological systems is critical. We report a chemistry-based capture-release-tag method for isolation of complex phospho-Ser/Thr-containing peptides by liquid beta-elimination combined with solid-phase Michael addition. The free thiol groups of 6-(mercapto-acetylamino)-hexanoic acid functionalized resin are used as immobilized Michael donors to capture dehydro-serine/threonine peptides. After an acid-mediated release step, phospho-peptides are labeled with a 6-(2-mercapto-acetylamine)-hexanoic amide tag at phosphorylated sites. We applied this method to analyze the phosphorylation status of microtubule-associated proteins. We find that a CDK5 substrate microtubule-associated protein 2 (MAP2) is phosphorylated on residues that are within a homologous region of Tau. The chemical method corroborates previous results and suggests that Tau and MAP2 may contain a CDK5 phosphorylation motif.
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Affiliation(s)
- Huang-Chun Tseng
- Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02155, USA.
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Kriz J, Beaulieu JM, Julien JP, Krnjević K. Up-regulation of peripherin is associated with alterations in synaptic plasticity in CA1 and CA3 regions of hippocampus. Neurobiol Dis 2005; 18:409-20. [PMID: 15686970 DOI: 10.1016/j.nbd.2004.10.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Revised: 09/08/2004] [Accepted: 10/13/2004] [Indexed: 11/29/2022] Open
Abstract
Peripherin is a type III intermediate filament protein normally undetectable in most brain neurons. Here, we report a similar pattern of peripherin expression in the brains of both mice treated with systemic injections of kainic acid (KA) and in peripherin transgenic mice (Per mice) over-expressing the normal peripherin gene under its own promoter. Double-immunofluorescence labeling revealed a partial co-localization of peripherin with the microtubule-associated protein MAP2, but not with neurofilament proteins. Electrophysiological studies revealed that synaptic plasticity was markedly altered in Per mice: in CA1, long-term potentiation (LTP) was decreased in Per slices (+29 +/- 2.0%, vs. +58 +/- 5.4%, in WT); while in CA3, LTP was increased in Per (+63 +/- 3.5% vs. +43 +/- 2.4.0%). In the hippocampus of Per mice, the levels of MAP2 were decreased, though synaptophysin and PSD95 remained unchanged. These intriguing findings suggest a role of peripherin in the alteration of hippocampal synaptic plasticity.
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Affiliation(s)
- Jasna Kriz
- Centre Hospitalier de l'Universite Laval Research Center, Quebec City, Quebec, Canada.
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Loftis JL, King DD, Colbert CM. Kinase-dependent loss of Na+ channel slow-inactivation in rat CA1 hippocampal pyramidal cell dendrites after brief exposure to convulsants. Eur J Neurosci 2003; 18:1029-32. [PMID: 12956702 DOI: 10.1046/j.1460-9568.2003.02832.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Na+ channels in the dendrites of rat CA1 pyramidal neurons display a profound activity-dependent inactivation, termed slow inactivation, that limits excitability in the dendrites even at low physiological rates of firing. The magnitude of this slow inactivation is powerfully modulated by a protein kinase C-dependent process. Because activation of kinases is a rapid and common feature of a number of seizure models, we hypothesized that a loss of slow inactivation of Na+ channels might exacerbate other changes in excitability. Thus, we observed the effects of a brief (5 min) chemical convulsant treatment on Na+ currents and action potentials in hippocampal slices. We found that slow inactivation decreased significantly and remained decreased for at least 30 min after return to control conditions. Pretreatment with either chelerythrine, a protein kinase C inhibitor, or U0126, a mitogen-activated protein kinase/extracellular signal regulated kinase kinase (MEK) inhibitor, blocked this reduction of slow inactivation. These results demonstrate that a brief period of hyperexcitability leads to a rapid, protein kinase-dependent loss of slow inactivation of Na+ channels that would contribute to and perhaps prolong the hyperexcitable state.
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Affiliation(s)
- Jordan L Loftis
- Department of Biology and Biochemistry, University of Houston, 4800 Calhoun Road, Houston, TX 77204-5513, USA
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Gómez-Ramos A, Díaz-Nido J, Smith MA, Perry G, Avila J. Effect of the lipid peroxidation product acrolein on tau phosphorylation in neural cells. J Neurosci Res 2003; 71:863-70. [PMID: 12605413 DOI: 10.1002/jnr.10525] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A hallmark of several neurodegenerative disorders, including Alzheimer's disease and tauopathies, is the hyperphosphorylation of the microtubule-associated protein tau. Tau phosphorylation by proline-directed and non-proline-directed protein kinases has been tested using antibodies PHF1 and 12E8, respectively. The effect of the lipid peroxidation product acrolein on these modes of phosphorylation has been assayed. We have found that acrolein, a peroxidation product from arachidonic acid, increases the phosphorylation of tau at the site recognized by PHF-1 both in human neuroblastoma cells and in primary cultures of mouse embryo cortical neurons. Whereas the basal phosphorylation of tau protein at the PHF1 site seems to be largely mediated by glycogen synthase kinase-3 (which is also activated in response to Abeta peptide), the acrolein-induced tau hyperphosphorylation at the same site is also due to p38 stress-activated kinase. These results support the view that oxidative stress and subsequent formation of lipid peroxidation products may contribute to tau protein phosphorylation in Alzheimer's disease and tauopathies.
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Affiliation(s)
- Alberto Gómez-Ramos
- Centro de Biología Molecular, (CSIC/UAM), Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
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