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Martini APR, Schlemmer LM, Lucio Padilha JA, Fabres RB, Couto Pereira NDS, Pereira LO, Dalmaz C, Netto CA. Acrobatic training prevents learning impairments and astrocyte remodeling in the hippocampus of rats undergoing chronic cerebral hypoperfusion: sex-specific benefits. FRONTIERS IN REHABILITATION SCIENCES 2024; 5:1375561. [PMID: 38939055 PMCID: PMC11208732 DOI: 10.3389/fresc.2024.1375561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/27/2024] [Indexed: 06/29/2024]
Abstract
Background Chronic cerebral hypoperfusion (CCH) leads to memory and learning impairments associated with degeneration and gliosis in the hippocampus. Treatment with physical exercise carries different therapeutic benefits for each sex. We investigated the effects of acrobatic training on astrocyte remodeling in the CA1 and CA3 subfields of the hippocampus and spatial memory impairment in male and female rats at different stages of the two-vessel occlusion (2VO) model. Methods Wistar rats were randomly allocated into four groups of males and females: 2VO acrobatic, 2VO sedentary, sham acrobatic, and sham sedentary. The acrobatic training was performed for 4 weeks prior to the 2VO procedure. Brain samples were collected for morphological and biochemical analysis at 3 and 7 days after 2VO. The dorsal hippocampi were removed and prepared for Western blot quantification of Akt, p-Akt, COX IV, cleaved caspase-3, PARP, and GFAP. GFAP immunofluorescence was performed on slices of the hippocampus to count astrocytes and apply the Sholl's circle technique. The Morris water maze was run after 45 days of 2VO. Results Acutely, the trained female rats showed increased PARP expression, and the 2VO-trained rats of both sexes presented increased GFAP levels in Western blot. Training, mainly in males, induced an increase in the number of astrocytes in the CA1 subfield. The 2VO rats presented branched astrocytes, while acrobatic training prevented branching. However, the 2VO-induced spatial memory impairment was partially prevented by the acrobatic training. Conclusion Acrobatic training restricted the astrocytic remodeling caused by 2VO in the CA1 and CA3 subfields of the hippocampus. The improvement in spatial memory was associated with more organized glial scarring in the trained rats and better cell viability observed in females.
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Affiliation(s)
- Ana Paula Rodrigues Martini
- Graduate Program in Neuroscience, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Livia Machado Schlemmer
- Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Graduate Program in Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Joelma Alves Lucio Padilha
- Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Graduate Program in Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Rafael Bandeira Fabres
- Department of Pediatrics, NorthShore University HealthSystem, Evanston, IL, United States
- Pritzker School of Medicine, University of Chicago, Chicago, IL, United States
| | - Natividade de Sá Couto Pereira
- Psychological Neuroscience Laboratory, Psychology Research Center, School of Psychology, University of Minho, Braga, Portugal
| | - Lenir Orlandi Pereira
- Graduate Program in Neuroscience, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carla Dalmaz
- Graduate Program in Neuroscience, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Graduate Program in Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carlos Alexandre Netto
- Graduate Program in Neuroscience, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Department of Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Graduate Program in Biochemistry, Institute of Basic Health Sciences, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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Role of NAD + and FAD in Ischemic Stroke Pathophysiology: An Epigenetic Nexus and Expanding Therapeutic Repertoire. Cell Mol Neurobiol 2022:10.1007/s10571-022-01287-4. [PMID: 36180651 DOI: 10.1007/s10571-022-01287-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 09/15/2022] [Indexed: 11/03/2022]
Abstract
The redox coenzymes viz., oxidized β-nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD) by way of generation of optimal reducing power and cellular energy currency (ATP), control a staggering array of metabolic reactions. The prominent cellular contenders for NAD+ utilization, inter alia, are sirtuins (SIRTs) and poly(ADP-ribose) polymerase (PARP-1), which have been significantly implicated in ischemic stroke (IS) pathogenesis. NAD+ and FAD are also two crucial epigenetic enzyme-required metabolites mediating histone deacetylation and poly(ADP-ribosyl)ation through SIRTs and PARP-1 respectively, and demethylation through FAD-mediated lysine specific demethylase activity. These enzymes and post-translational modifications impinge on the components of neurovascular unit, primarily neurons, and elicit diverse functional upshots in an ischemic brain. These could be circumstantially linked with attendant cognitive deficits and behavioral outcomes in post-stroke epoch. Parsing out the contribution of NAD+/FAD-synthesizing and utilizing enzymes towards epigenetic remodeling in IS setting, together with their cognitive and behavioral associations, combined with possible therapeutic implications will form the crux of this review.
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Dastidar SG, Nair D. A Ribosomal Perspective on Neuronal Local Protein Synthesis. Front Mol Neurosci 2022; 15:823135. [PMID: 35283723 PMCID: PMC8904363 DOI: 10.3389/fnmol.2022.823135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 01/17/2022] [Indexed: 11/15/2022] Open
Abstract
Continued mRNA translation and protein production are critical for various neuronal functions. In addition to the precise sorting of proteins from cell soma to distant locations, protein synthesis allows a dynamic remodeling of the local proteome in a spatially variable manner. This spatial heterogeneity of protein synthesis is shaped by several factors such as injury, guidance cues, developmental cues, neuromodulators, and synaptic activity. In matured neurons, thousands of synapses are non-uniformly distributed throughout the dendritic arbor. At any given moment, the activity of individual synapses varies over a wide range, giving rise to the variability in protein synthesis. While past studies have primarily focused on the translation factors or the identity of translated mRNAs to explain the source of this variation, the role of ribosomes in this regard continues to remain unclear. Here, we discuss how several stochastic mechanisms modulate ribosomal functions, contributing to the variability in neuronal protein expression. Also, we point out several underexplored factors such as local ion concentration, availability of tRNA or ATP during translation, and molecular composition and organization of a compartment that can influence protein synthesis and its variability in neurons.
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Gao Y, Bai L, Zhou W, Yang Y, Zhang J, Li L, Jiang M, Mi Y, Li TT, Zhang X, Zhang W, Xu JT. PARP-1-regulated TNF-α expression in the dorsal root ganglia and spinal dorsal horn contributes to the pathogenesis of neuropathic pain in rats. Brain Behav Immun 2020; 88:482-496. [PMID: 32283287 DOI: 10.1016/j.bbi.2020.04.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 01/04/2023] Open
Abstract
Emerging evidence has implicated poly-(ADP-ribose) polymerase 1 (PARP-1), a transcriptional coregulator, in a variety of inflammatory diseases. In the current study, the role of PARP-1 in neuropathic pain and the underlying mechanisms were investigated. Neuropathic pain was determined by assessing the paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) following lumbar 5 spinal nerve ligation (SNL) in male rates. Western blotting, qRT-PCR, immunohistochemistry, chromatin immunoprecipitation (ChIP), and Co-IP assays were performed to elucidate the mechanisms. The results showed that SNL resulted in a significant increase in the expression and activation of PARP-1 in the ipsilateral L4/5 dorsal root ganglia (DRG) and spinal dorsal horn, which occurred on day one, reached peak on day 7, and persisted more than 2 weeks after surgery. Double immunofluorescence staining revealed that PARP-1 was expressed exclusively in DRG A-type and C-type neurons. In the spinal cord, PARP-1 mainly colocalized with the neuronal marker NeuN and the astrocytic marker GFAP specifically in the superficial lamina. Prior intrathecal (i.t.) injection of PJ-34, a PARPs inhibitor, or Tiq-A, a specific PARP-1 inhibitor, dose-dependently prevented the reductions in PWT and PWL following SNL. Established neuropathic pain-like hypersensitivity was also attenuated with i.t. injection of PJ-34 and Tiq-A starting on day 7 following SNL, a timepoint at which neuropathic pain was fully established. SNL-induced mechanical allodynia and thermal hyperalgesia were also alleviated by i.t. injection of PARP-1 siRNA following a reduction in PARP-1 expression in the dorsal horn. Moreover, the SNL-induced increases in TNF-α protein and mRNA in the dorsal horn and DRG were dramatically suppressed by i.t. injection of Tiq-A or PARP-1 siRNA. The i.t. lipopolysaccharide (LPS)-induced increase in the production of TNF-α in the dorsal horn was also inhibited by prior to i.t. injection of PARP-1 siRNA. Results of ChIP assay showed that SNL-induced PARP-1 activation promoted the binding of NF-κB p65 with the TNF-α promoter in the dorsal horn and that PARP-1 inhibition reduced this binding and suppressed TNF-α expression. Co-IP assay revealed that SNL caused a significant increase in the level of histone H1 poly(ADP)-ribosylation. Together, these results indicate that PARP-1-regulated TNF-α expression in the DRG and spinal dorsal horn following SNL contributes to the development and maintenance of neuropathic pain. Targeting PARP-1 might be a promising therapeutic strategy for the treatment of the chronic pain.
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Affiliation(s)
- Yan Gao
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Liying Bai
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China; Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital, Zhengzhou University, 1 Jianshe East Road, Zhengzhou 450052, China
| | - Wenjuan Zhou
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China; Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital, Zhengzhou University, 1 Jianshe East Road, Zhengzhou 450052, China
| | - Yin Yang
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Jian Zhang
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Liren Li
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Mingjun Jiang
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Yang Mi
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Tong-Tong Li
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Xuan Zhang
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China
| | - Wei Zhang
- Department of Anesthesiology, Pain and Perioperative Medicine, The First Affiliated Hospital, Zhengzhou University, 1 Jianshe East Road, Zhengzhou 450052, China
| | - Ji-Tian Xu
- Department of Physiology and Neurobiology, School of Basic Medical Sciences, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China; Neuroscience Research Institute, Zhengzhou University, 100 Science Avenue, Zhengzhou 450001, China.
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Evidence for Decreased Nucleolar PARP-1 as an Early Marker of Cognitive Impairment. Neural Plast 2019; 2019:4383258. [PMID: 31827497 PMCID: PMC6885846 DOI: 10.1155/2019/4383258] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 09/11/2019] [Accepted: 10/01/2019] [Indexed: 11/21/2022] Open
Abstract
Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear protein that regulates gene expression through poly(ADP)-ribosylation, resulting in the loosening of chromatin structure. PARP-1 enzymatic activity has been shown to be necessary for the expression of several genes required for memory formation and consolidation. Previously, we showed that nucleolar PARP-1 is significantly decreased in hippocampal pyramidal cells in Alzheimer's disease (AD). We proposed that the displacement of PARP-1 from the nucleolus results in downregulation of new rRNA expression and ribosome biogenesis, leading to cognitive impairment. To further investigate the relationship between nucleolar PARP-1 and memory impairment, we examined PARP-1 expression in the hippocampi of individuals with mild cognitive impairment (MCI) compared to control and AD cases. We used immunohistochemical techniques to examine the nucleolar distribution of PARP-1 in the Cornu Ammonis (CA region) of the hippocampus. PARP-1 positive cells were then scored for the presence or absence of PARP-1 in the nucleolus. We found a significant decrease of PARP-1 staining in the nucleolar compartment of hippocampal pyramidal cells in MCI compared with Control and AD. When the four CA (CA1-4) regions were considered separately, only the CA1 region showed significant differences in nucleolar PARP-1 with Control > AD > MCI cases. Categorization of nucleolar PARP-1 into “distinct” and “diffuse” groups suggest that most of the changes occur within the distinct group. In addition, measurements of the nucleolar diameter of nucleolar PARP-1 positive cells in CA2 and CA4 showed Control > MCI. Thus, MCI cases had a lower percentage of PARP-1 nucleolar positive cells in CA1 and smaller nucleolar diameters in CA2 and CA4, compared to Control. Our data suggest that disruption of nucleolar form and function is an early and important step in the progression of cognitive impairment.
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Elibol B, Terzioglu-Usak S, Beker M, Sahbaz C. Thymoquinone (TQ) demonstrates its neuroprotective effect via an anti-inflammatory action on the Aβ(1–42)-infused rat model of Alzheimer's disease. PSYCHIAT CLIN PSYCH 2019. [DOI: 10.1080/24750573.2019.1673945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022] Open
Affiliation(s)
- Birsen Elibol
- Department of Medical Biology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
| | - Sule Terzioglu-Usak
- Department of Medical Biology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
| | - Merve Beker
- Department of Medical Biology, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
| | - Cigdem Sahbaz
- Department of Psychiatry, Faculty of Medicine, Bezmialem Vakif University, Istanbul, Turkey
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Toro CA, Zhang L, Cao J, Cai D. Sex differences in Alzheimer's disease: Understanding the molecular impact. Brain Res 2019; 1719:194-207. [PMID: 31129153 DOI: 10.1016/j.brainres.2019.05.031] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/10/2019] [Accepted: 05/22/2019] [Indexed: 12/14/2022]
Abstract
Alzheimer's disease (AD) is a common neurodegenerative disorder that presents with cognitive impairment and behavioral disturbance. Approximately 5.5 million people in the United States live with AD, most of whom are over the age of 65 with two-thirds being woman. There have been major advancements over the last decade or so in the understanding of AD neuropathological changes and genetic involvement. However, studies of sex impact in AD have not been adequately integrated into the investigation of disease development and progression. It becomes indispensable to acknowledge in both basic science and clinical research studies the importance of understanding sex-specific differences in AD pathophysiology and pathogenesis, which could guide future effort in the discovery of novel targets for AD. Here, we review the latest and most relevant literature on this topic, highlighting the importance of understanding sex dimorphism from a molecular perspective and its association to clinical trial design and development in AD research field.
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Affiliation(s)
- Carlos A Toro
- National Center for the Medical Consequences of Spinal Cord Injury, James J Peters VA Medical Center, Bronx, NY 10468, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
| | - Larry Zhang
- Research and Development, James J Peters VA Medical Center, Bronx, NY 10468, United States; Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Jiqing Cao
- Research and Development, James J Peters VA Medical Center, Bronx, NY 10468, United States; Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
| | - Dongming Cai
- Research and Development, James J Peters VA Medical Center, Bronx, NY 10468, United States; Neurology Section, James J Peters VA Medical Center, Bronx, NY 10468, United States; Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
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Learning-induced ribosomal RNA is required for memory consolidation in mice-Evidence of differentially expressed rRNA variants in learning and memory. PLoS One 2018; 13:e0203374. [PMID: 30281601 PMCID: PMC6169870 DOI: 10.1371/journal.pone.0203374] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 08/20/2018] [Indexed: 12/01/2022] Open
Abstract
The transition from short-term to long-term forms of synaptic plasticity requires protein synthesis and new gene expression. Most efforts to understand experience-induced changes in neuronal gene expression have focused on the transcription products of RNA polymerase II—primarily mRNAs and the proteins they encode. We recently showed that nucleolar integrity and activity-dependent ribosomal RNA (rRNA) synthesis are essential for the maintenance of hippocampal long-term potentiation (LTP). Consequently, the synaptic plasticity and memory hypothesis predicts that nucleolar integrity and activity dependent rRNA synthesis would be required for Long-term memory (LTM). We tested this prediction using the hippocampus-dependent, Active Place Avoidance (APA) spatial memory task and found that training induces de novo rRNA synthesis in mouse dorsal hippocampus. This learning-induced increase in nucleolar activity and rRNA synthesis persists at least 24 h after training. In addition, intra-hippocampal injection of the Pol I specific inhibitor, CX-5461 prior to training, revealed that de novo rRNA synthesis is required for 24 h memory, but not for learning. Using qPCR to assess activity-dependent changes in gene expression, we found that of seven known rRNA expression variants (v-rRNAs), only one, v-rRNA IV, is significantly upregulated right after training. These data indicate that learning induced v-rRNAs are crucial for LTM, and constitute the first evidence that differential rRNA gene expression plays a role in memory.
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Azad GK, Ito K, Sailaja BS, Biran A, Nissim-Rafinia M, Yamada Y, Brown DT, Takizawa T, Meshorer E. PARP1-dependent eviction of the linker histone H1 mediates immediate early gene expression during neuronal activation. J Cell Biol 2017; 217:473-481. [PMID: 29284668 PMCID: PMC5800798 DOI: 10.1083/jcb.201703141] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 10/12/2017] [Accepted: 11/22/2017] [Indexed: 01/08/2023] Open
Abstract
Neuronal stimulation leads to the expression of immediate early genes (IEGs). Azad et al. show that neuronal depolarization induces replacement of the linker histone H1 by PARP1 at IEG promoters in a manner that requires H1 phosphorylation and H1 poly-ADP ribosylation. Neuronal stimulation leads to immediate early gene (IEG) expression through calcium-dependent mechanisms. In recent years, considerable attention has been devoted to the transcriptional responses after neuronal stimulation, but relatively little is known about the changes in chromatin dynamics that follow neuronal activation. Here, we use fluorescence recovery after photobleaching, biochemical fractionations, and chromatin immunoprecipitation to show that KCl-induced depolarization in primary cultured cortical neurons causes a rapid release of the linker histone H1 from chromatin, concomitant with IEG expression. H1 release is repressed by PARP inhibition, PARP1 deletion, a non-PARylatable H1, as well as phosphorylation inhibitions and a nonphosphorylatable H1, leading to hindered IEG expression. Further, H1 is replaced by PARP1 on IEG promoters after neuronal stimulation, and PARP inhibition blocks this reciprocal binding response. Our results demonstrate the relationship between neuronal excitation and chromatin plasticity by identifying the roles of polyadenosine diphosphate ribosylation and phosphorylation of H1 in regulating H1 chromatin eviction and IEG expression in stimulated neurons.
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Affiliation(s)
- Gajendra Kumar Azad
- Department of Genetics, The Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kenji Ito
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Badi Sri Sailaja
- Department of Genetics, The Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Alva Biran
- Department of Genetics, The Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Malka Nissim-Rafinia
- Department of Genetics, The Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yasuhiro Yamada
- Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - David T Brown
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, MS
| | - Takumi Takizawa
- Department of Pediatrics, Graduate School of Medicine, Gunma University, Gunma, Japan
| | - Eran Meshorer
- Department of Genetics, The Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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A transcriptomics approach uncovers novel roles for poly(ADP-ribosyl)ation in the basal defense response in Arabidopsis thaliana. PLoS One 2017; 12:e0190268. [PMID: 29284022 PMCID: PMC5746271 DOI: 10.1371/journal.pone.0190268] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 12/10/2017] [Indexed: 12/20/2022] Open
Abstract
Pharmacological inhibition of poly(ADP-ribose) polymerase (PARP) or loss of Arabidopsis thaliana PARG1 (poly(ADP-ribose) glycohydrolase) disrupt a subset of plant defenses. In the present study we examined the impact of altered poly(ADP-ribosyl)ation on early gene expression induced by the microbe-associate molecular patterns (MAMPs) flagellin (flg22) and EF-Tu (elf18). Stringent statistical analyses and filtering identified 178 genes having MAMP-induced mRNA abundance patterns that were altered by either PARP inhibitor 3-aminobenzamide (3AB) or PARG1 knockout. From the identified set of 178 genes, over fifty Arabidopsis T-DNA insertion lines were chosen and screened for altered basal defense responses. Subtle alterations in callose deposition and/or seedling growth in response to those MAMPs were observed in knockouts of At3g55630 (FPGS3, a cytosolic folylpolyglutamate synthetase), At5g15660 (containing an F-box domain), At1g47370 (a TIR-X (Toll-Interleukin Receptor domain)), and At5g64060 (a predicted pectin methylesterase inhibitor). Over-represented GO terms for the gene expression study included "innate immune response" for elf18/parg1, highlighting a subset of elf18-activated defense-associated genes whose expression is altered in parg1 plants. The study also allowed a tightly controlled comparison of early mRNA abundance responses to flg22 and elf18 in wild-type Arabidopsis, which revealed many differences. The PARP inhibitor 3-methoxybenzamide (3MB) was also used in the gene expression profiling, but pleiotropic impacts of this inhibitor were observed. This transcriptomics study revealed targets for further dissection of MAMP-induced plant immune responses, impacts of PARP inhibitors, and the molecular mechanisms by which poly(ADP-ribosyl)ation regulates plant responses to MAMPs.
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PARP-1 is required for retrieval of cocaine-associated memory by binding to the promoter of a novel gene encoding a putative transposase inhibitor. Mol Psychiatry 2017; 22:570-579. [PMID: 27595592 DOI: 10.1038/mp.2016.119] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 05/24/2016] [Accepted: 06/01/2016] [Indexed: 12/30/2022]
Abstract
Reward-related memory is an important factor in cocaine seeking. One necessary signaling mechanism for long-term memory formation is the activation of poly(ADP-ribose) polymerase-1 (PARP-1), via poly(ADP-ribosyl)ation. We demonstrate herein that auto-poly(ADP-ribosyl)ation of activated PARP-1 was significantly pronounced during retrieval of cocaine-associated contextual memory, in the central amygdala (CeA) of rats expressing cocaine-conditioned place preference (CPP). Intra-CeA pharmacological and short hairpin RNA depletion of PARP-1 activity during cocaine-associated memory retrieval abolished CPP. In contrast, PARP-1 inhibition after memory retrieval did not affect CPP reconsolidation process and subsequent retrievals. Chromatin immunoprecipitation sequencing revealed that PARP-1 binding in the CeA is highly enriched in genes involved in neuronal signaling. We identified among PARP targets in CeA a single gene, yet uncharacterized and encoding a putative transposase inhibitor, at which PARP-1 enrichment markedly increases during cocaine-associated memory retrieval and positively correlates with CPP. Our findings have important implications for understanding drug-related behaviors, and suggest possible future therapeutic targets for drug abuse.
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A PARP1-ERK2 synergism is required for the induction of LTP. Sci Rep 2016; 6:24950. [PMID: 27121568 PMCID: PMC4848477 DOI: 10.1038/srep24950] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 04/08/2016] [Indexed: 12/18/2022] Open
Abstract
Unexpectedly, a post-translational modification of DNA-binding proteins, initiating the cell response to single-strand DNA damage, was also required for long-term memory acquisition in a variety of learning paradigms. Our findings disclose a molecular mechanism based on PARP1-Erk synergism, which may underlie this phenomenon. A stimulation induced PARP1 binding to phosphorylated Erk2 in the chromatin of cerebral neurons caused Erk-induced PARP1 activation, rendering transcription factors and promoters of immediate early genes (IEG) accessible to PARP1-bound phosphorylated Erk2. Thus, Erk-induced PARP1 activation mediated IEG expression implicated in long-term memory. PARP1 inhibition, silencing, or genetic deletion abrogated stimulation-induced Erk-recruitment to IEG promoters, gene expression and LTP generation in hippocampal CA3-CA1-connections. Moreover, a predominant binding of PARP1 to single-strand DNA breaks, occluding its Erk binding sites, suppressed IEG expression and prevented the generation of LTP. These findings outline a PARP1-dependent mechanism required for LTP generation, which may be implicated in long-term memory acquisition and in its deterioration in senescence.
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Nucleolar PARP-1 Expression Is Decreased in Alzheimer's Disease: Consequences for Epigenetic Regulation of rDNA and Cognition. Neural Plast 2016; 2016:8987928. [PMID: 27034851 PMCID: PMC4789469 DOI: 10.1155/2016/8987928] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/02/2016] [Indexed: 11/18/2022] Open
Abstract
Synaptic dysfunction is thought to play a major role in memory impairment in Alzheimer's disease (AD). PARP-1 has been identified as an epigenetic regulator of plasticity and memory. Thus, we hypothesize that PARP-1 may be altered in postmortem hippocampus of individuals with AD compared to age-matched controls without neurologic disease. We found a reduced level of PARP-1 nucleolar immunohistochemical staining in hippocampal pyramidal cells in AD. Nucleolar PARP-1 staining ranged from dispersed and less intense to entirely absent in AD compared to the distinct nucleolar localization in hippocampal pyramidal neurons in controls. In cases of AD, the percentage of hippocampal pyramidal cells with nucleoli that were positive for both PARP-1 and the nucleolar marker fibrillarin was significantly lower than in controls. PARP-1 nucleolar expression emerges as a sensitive marker of functional changes in AD and suggests a novel role for PARP-1 dysregulation in AD pathology.
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Cohen-Armon M. A PARP1-Erk2 synergism is required for stimulation-induced expression of immediate early genes. GENE & TRANSLATIONAL BIOINFORMATICS 2016; 2:e1367. [PMID: 27857998 PMCID: PMC5110042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A PARP1-Erk2 synergism was required to generate synaptic long-term potentiation in the CA3-CA1 hippocampal connections. This molecular mechanism was associated with the recently identified pivotal role of polyADP-ribosylation in learning. High frequency electrical stimulation of cortical and hippocampal neurons induced binding of phosphorylated Erk2 (transported into the nucleus) to the nuclear protein PARP1. PARP1-Erk2 binding induced PARP1 activation and polyADP-ribosylation of its prominent substrate, linker histone H1. A facilitated access of PARP1-bound phosphorylated Erk2 to its substrates, transcription factors Elk1 and CREB was attributed to the release of polyADP-ribosylated H1 from the DNA, causing local DNA relaxation. Erk-induced phosphorylation of transcription factors activating the HAT activity of CBP (CREB binding protein), recruited acetylated histone H4 to the promoters of immediate early genes (IEG) cfos, zif268 and arc, which are implicated in synaptic plasticity. In accordance, their induced expression was suppressed after PARP1 genetic deletion in PARP1-KO mice, or after PARP1 inhibition or silencing. Moreover, under these conditions, long-term synaptic potentiation (LTP) (indicating synaptic plasticity) was not generation in the hippocampal CA3-CA1 connections, and learning abilities were impaired. Furthermore, both IEG expression and LTP generation failed when cerebral neurons accumulated single strand DNA breaks, due to a predominant binding of PARP1 to nicked DNA, occluding its Erk binding sites. Thus, a declined synaptic plasticity is anticipated when aged cerebral neurons accumulate DNA single-strand breaks during life span.
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Affiliation(s)
- M. Cohen-Armon
- Department of Physiology and Pharmacology, Sackler School of Medicine, and the Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, 69978, Israel
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Inaba H, Tsukagoshi A, Kida S. PARP-1 activity is required for the reconsolidation and extinction of contextual fear memory. Mol Brain 2015; 8:63. [PMID: 26471780 PMCID: PMC4608138 DOI: 10.1186/s13041-015-0153-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 10/07/2015] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Memory consolidation, reconsolidation, and extinction have been shown to require new gene expression. Poly ADP-ribosylation mediated by poly (ADP-ribose) polymerase-1 (PARP-1) is known to regulate transcription through histone modification. Recent studies have suggested that PARP-1 positively regulates the formation of long-term memory (LTM); however, the roles of PARP-1 in memory processes, especially processes after retrieval, remain unknown. RESULTS Here, we show critical roles for PARP-1 in the consolidation, reconsolidation, and extinction of contextual fear memory in mice. We examined the effects of pharmacological inhibition of PARP-1 activity in the hippocampus or medial prefrontal cortex (mPFC) on these memory processes. Similarly with previous findings, a micro-infusion of the PARP-1 inhibitor 3-aminobenzamide or PJ34 into the dorsal hippocampus, but not mPFC, impaired LTM formation without affecting short-term memory (STM). Importantly, this pharmacological blockade of PARP-1 in the dorsal hippocampus, but not mPFC, also disrupted post-reactivation LTM without affecting post-reactivation STM. Conversely, micro-infusion of the PARP-1 inhibitors into the mPFC, but not dorsal hippocampus, blocked long-term extinction. Additionally, systemic administration of the PARP-1 inhibitor Tiq-A blocked c-fos induction in the hippocampus, which is observed when memory is consolidated or reconsolidated, and also blocked c-fos induction in the mPFC, which is observed when memory is extinguished. CONCLUSIONS Our observations showed that PARP-1 activation is required for the consolidation, reconsolidation, and extinction of contextual fear memory and suggested that PARP-1 contributes to the new gene expression necessary for these memory processes.
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Affiliation(s)
- Hiroyoshi Inaba
- Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502, Japan.
| | - Akinori Tsukagoshi
- Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502, Japan.
| | - Satoshi Kida
- Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502, Japan.
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, 332-0012, Japan.
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Optimized deep-targeted proteotranscriptomic profiling reveals unexplored Conus toxin diversity and novel cysteine frameworks. Proc Natl Acad Sci U S A 2015; 112:E3782-91. [PMID: 26150494 DOI: 10.1073/pnas.1501334112] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cone snails are predatory marine gastropods characterized by a sophisticated venom apparatus responsible for the biosynthesis and delivery of complex mixtures of cysteine-rich toxin peptides. These conotoxins fold into small highly structured frameworks, allowing them to potently and selectively interact with heterologous ion channels and receptors. Approximately 2,000 toxins from an estimated number of >70,000 bioactive peptides have been identified in the genus Conus to date. Here, we describe a high-resolution interrogation of the transcriptomes (available at www.ddbj.nig.ac.jp) and proteomes of the diverse compartments of the Conus episcopatus venom apparatus. Using biochemical and bioinformatic tools, we found the highest number of conopeptides yet discovered in a single Conus specimen, with 3,305 novel precursor toxin sequences classified into 9 known superfamilies (A, I1, I2, M, O1, O2, S, T, Z), and identified 16 new superfamilies showing unique signal peptide signatures. We were also able to depict the largest population of venom peptides containing the pharmacologically active C-C-CC-C-C inhibitor cystine knot and CC-C-C motifs (168 and 44 toxins, respectively), as well as 208 new conotoxins displaying odd numbers of cysteine residues derived from known conotoxin motifs. Importantly, six novel cysteine-rich frameworks were revealed which may have novel pharmacology. Finally, analyses of codon usage bias and RNA-editing processes of the conotoxin transcripts demonstrate a specific conservation of the cysteine skeleton at the nucleic acid level and provide new insights about the origin of sequence hypervariablity in mature toxin regions.
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Hernández AI, Alarcon JM, Allen KD. New ribosomes for new memories? Commun Integr Biol 2015; 8:e1017163. [PMID: 26479998 PMCID: PMC4594611 DOI: 10.1080/19420889.2015.1017163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 01/23/2015] [Accepted: 01/26/2015] [Indexed: 01/13/2023] Open
Abstract
Widely thought to be a housekeeping process, the regulation and synthesis of rRNA emerges as a potentially central mechanism for the maintenance of synaptic plasticity and memory. We have recently shown that an essential component of late-phase synaptic plasticity is rRNA biosynthesis — the rate-limiting step in the production of new ribosomes. We hypothesize that a particular population of ribosomes is generated upon learning-associated neural activity to alter the rate of synthesis of plasticity factors at tagged synapses that will support the maintenance of synaptic plasticity and memory.
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Affiliation(s)
- A Iván Hernández
- Department of Pathology; State University of New York; Downstate Medical Center ; Brooklyn, New York ; The Robert F. Furchgott Center for Neural and Behavioral Science; State University of New York; Downstate Medical Center ; Brooklyn, New York
| | - Juan M Alarcon
- Department of Pathology; State University of New York; Downstate Medical Center ; Brooklyn, New York ; The Robert F. Furchgott Center for Neural and Behavioral Science; State University of New York; Downstate Medical Center ; Brooklyn, New York
| | - Kim D Allen
- Department of Pathology; State University of New York; Downstate Medical Center ; Brooklyn, New York
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Allen KD, Gourov AV, Harte C, Gao P, Lee C, Sylvain D, Splett JM, Oxberry WC, van de Nes PS, Troy-Regier MJ, Wolk J, Alarcon JM, Hernández AI. Nucleolar integrity is required for the maintenance of long-term synaptic plasticity. PLoS One 2014; 9:e104364. [PMID: 25089620 PMCID: PMC4121280 DOI: 10.1371/journal.pone.0104364] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 07/10/2014] [Indexed: 01/10/2023] Open
Abstract
Long-term memory (LTM) formation requires new protein synthesis and new gene expression. Based on our work in Aplysia, we hypothesized that the rRNA genes, stimulation-dependent targets of the enzyme Poly(ADP-ribose) polymerase-1 (PARP-1), are primary effectors of the activity-dependent changes in synaptic function that maintain synaptic plasticity and memory. Using electrophysiology, immunohistochemistry, pharmacology and molecular biology techniques, we show here, for the first time, that the maintenance of forskolin-induced late-phase long-term potentiation (L-LTP) in mouse hippocampal slices requires nucleolar integrity and the expression of new rRNAs. The activity-dependent upregulation of rRNA, as well as L-LTP expression, are poly(ADP-ribosyl)ation (PAR) dependent and accompanied by an increase in nuclear PARP-1 and Poly(ADP) ribose molecules (pADPr) after forskolin stimulation. The upregulation of PARP-1 and pADPr is regulated by Protein kinase A (PKA) and extracellular signal-regulated kinase (ERK)--two kinases strongly associated with long-term plasticity and learning and memory. Selective inhibition of RNA Polymerase I (Pol I), responsible for the synthesis of precursor rRNA, results in the segmentation of nucleoli, the exclusion of PARP-1 from functional nucleolar compartments and disrupted L-LTP maintenance. Taken as a whole, these results suggest that new rRNAs (28S, 18S, and 5.8S ribosomal components)--hence, new ribosomes and nucleoli integrity--are required for the maintenance of long-term synaptic plasticity. This provides a mechanistic link between stimulation-dependent gene expression and the new protein synthesis known to be required for memory consolidation.
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Affiliation(s)
- Kim D. Allen
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- Department of Biology, School of Science, Health and Technology, City University of New York, Medgar Evers College, Brooklyn, New York, United States of America
| | - Andrei V. Gourov
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Christopher Harte
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Peng Gao
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Clarice Lee
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Darlene Sylvain
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Joshua M. Splett
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - William C. Oxberry
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- The Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Paula S. van de Nes
- Departments of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Matthew J. Troy-Regier
- Departments of Physiology and Pharmacology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Jason Wolk
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
| | - Juan M. Alarcon
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- The Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- * E-mail: (JMA); (AIH)
| | - A. Iván Hernández
- Department of Pathology, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- The Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York, Downstate Medical Center, Brooklyn, New York, United States of America
- * E-mail: (JMA); (AIH)
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Stoica BA, Loane DJ, Zhao Z, Kabadi SV, Hanscom M, Byrnes KR, Faden AI. PARP-1 inhibition attenuates neuronal loss, microglia activation and neurological deficits after traumatic brain injury. J Neurotrauma 2014; 31:758-72. [PMID: 24476502 DOI: 10.1089/neu.2013.3194] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Traumatic brain injury (TBI) causes neuronal cell death as well as microglial activation and related neurotoxicity that contribute to subsequent neurological dysfunction. Poly (ADP-ribose) polymerase (PARP-1) induces neuronal cell death through activation of caspase-independent mechanisms, including release of apoptosis inducing factor (AIF), and microglial activation. Administration of PJ34, a selective PARP-1 inhibitor, reduced cell death of primary cortical neurons exposed to N-Methyl-N'-Nitro-N-Nitrosoguanidine (MNNG), a potent inducer of AIF-dependent cell death. PJ34 also attenuated lipopolysaccharide and interferon-γ-induced activation of BV2 or primary microglia, limiting NF-κB activity and iNOS expression as well as decreasing generation of reactive oxygen species and TNFα. Systemic administration of PJ34 starting as late as 24 h after controlled cortical impact resulted in improved motor function recovery in mice with TBI. Stereological analysis demonstrated that PJ34 treatment reduced the lesion volume, attenuated neuronal cell loss in the cortex and thalamus, and reduced microglial activation in the TBI cortex. PJ34 treatment did not improve cognitive performance in a Morris water maze test or reduce neuronal cell loss in the hippocampus. Overall, our data indicate that PJ34 has a significant, albeit selective, neuroprotective effect after experimental TBI, and its therapeutic effect may be from multipotential actions on neuronal cell death and neuroinflammatory pathways.
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Affiliation(s)
- Bogdan A Stoica
- 1 Department of Anesthesiology, Center for Shock, Trauma and Anesthesiology Research (STAR), National Study Center for Trauma and EMS, University of Maryland , School of Medicine, Baltimore, Maryland
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Gavin DP, Floreani C. Epigenetics of schizophrenia: an open and shut case. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 115:155-201. [PMID: 25131545 DOI: 10.1016/b978-0-12-801311-3.00005-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
During the last decade and a half, there has been an explosion of data regarding epigenetic changes in schizophrenia. Most initial studies have suggested that schizophrenia is characterized by an overly restrictive chromatin state based on increases in transcription silencing histone modifications and DNA methylation at schizophrenia candidate gene promoters and increases in the expression of enzymes that catalyze their formation. However, recent studies indicate that the pathology is more complex. This complexity may greatly impact pharmacological approaches directed at targeting epigenetic abnormalities in schizophrenia. The current review explores epigenetic studies of schizophrenia and what this can tell us about the underlying pathophysiology. We hypothesize based on recent studies that it is also plausible that drugs that further restrict chromatin may be efficacious.
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Affiliation(s)
- David P Gavin
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA.
| | - Christina Floreani
- Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, USA; Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, USA
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21
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Hernández AI, Oxberry WC, Crary JF, Mirra SS, Sacktor TC. Cellular and subcellular localization of PKMζ. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130140. [PMID: 24298142 DOI: 10.1098/rstb.2013.0140] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In contrast to protein kinases that participate in long-term potentiation (LTP) induction and memory consolidation, the autonomously active atypical protein kinase C isoform, protein kinase Mzeta (PKMζ), functions in the core molecular mechanism of LTP maintenance and long-term memory storage. Here, using multiple complementary techniques for light and electron microscopic immunolocalization, we present the first detailed characterization of the cellular and subcellular distribution of PKMζ in rat hippocampus and neocortex. We find that PKMζ is widely expressed in forebrain with prominent immunostaining in hippocampal and neocortical grey matter, and weak label in white matter. In hippocampal and cortical pyramidal cells, PKMζ expression is predominantly somatodendritic, and electron microscopy highlights the kinase at postsynaptic densities and in clusters within spines. In addition, nuclear label and striking punctate immunopositive structures in a paranuclear and dendritic distribution are seen by confocal microscopy, occasionally at dendritic bifurcations. PKMζ immunoreactive granules are observed by electron microscopy in cell bodies and dendrites, including endoplasmic reticulum. The widespread distribution of PKMζ in nuclei, nucleoli and endoplasmic reticulum suggests potential roles of this kinase in cell-wide mechanisms involving gene expression, biogenesis of ribosomes and new protein synthesis. The localization of PKMζ within postsynaptic densities and spines suggests sites where the kinase stores information during LTP maintenance and long-term memory.
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Affiliation(s)
- A Iván Hernández
- Department of Pathology, State University of New York, Downstate Medical Center, , Brooklyn, NY, USA
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22
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Gavin DP, Chase KA, Sharma RP. Active DNA demethylation in post-mitotic neurons: a reason for optimism. Neuropharmacology 2013; 75:233-45. [PMID: 23958448 DOI: 10.1016/j.neuropharm.2013.07.036] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 07/22/2013] [Accepted: 07/30/2013] [Indexed: 12/13/2022]
Abstract
Over the last several years proteins involved in base excision repair (BER) have been implicated in active DNA demethylation. We review the literature supporting BER as a means of active DNA demethylation, and explain how the various components function and cooperate to remove the potentially most enduring means of epigenetic gene regulation. Recent evidence indicates that the same pathways implicated during periods of widespread DNA demethylation, such as the erasure of methyl marks in the paternal pronucleus soon after fertilization, are operational in post-mitotic neurons. Neuronal functional identities, defined here as the result of a combination of neuronal subtype, location, and synaptic connections are largely maintained through DNA methylation. Chronic mental illnesses, such as schizophrenia, may be the result of both altered neurotransmitter levels and neurons that have assumed dysfunctional neuronal identities. A limitation of most current psychopharmacological agents is their focus on the former, while not addressing the more profound latter pathophysiological process. Previously, it was believed that active DNA demethylation in post-mitotic neurons was rare if not impossible. If this were the case, then reversing the factors that maintain neuronal identity, would be highly unlikely. The emergence of an active DNA demethylation pathway in the brain is a reason for great optimism in psychiatry as it provides a means by which previously pathological neurons may be reprogrammed to serve a more favorable role. Agents targeting epigenetic processes have shown much promise in this regard, and may lead to substantial gains over traditional pharmacological approaches.
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Affiliation(s)
- David P Gavin
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60612, USA; Jesse Brown Veterans Affairs Medical Center, 820 South Damen Avenue (M/C 151), Chicago, IL 60612, USA.
| | - Kayla A Chase
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60612, USA
| | - Rajiv P Sharma
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 W. Taylor St., Chicago, IL 60612, USA; Jesse Brown Veterans Affairs Medical Center, 820 South Damen Avenue (M/C 151), Chicago, IL 60612, USA
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De Maio A, Natale E, Rotondo S, Di Cosmo A, Faraone-Mennella MR. Vault-poly-ADP-ribose polymerase in the Octopus vulgaris brain: a regulatory factor of actin polymerization dynamic. Comp Biochem Physiol B Biochem Mol Biol 2013; 166:40-7. [PMID: 23831359 DOI: 10.1016/j.cbpb.2013.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 06/11/2013] [Accepted: 06/24/2013] [Indexed: 01/14/2023]
Abstract
Our previous behavioural, biochemical and immunohistochemical analyses conducted in selected regions (supra/sub oesophageal masses) of the Octopus vulgaris brain detected a cytoplasmic poly-ADP-ribose polymerase (more than 90% of total enzyme activity). The protein was identified as the vault-free form of vault-poly-ADP-ribose polymerase. The present research extends and integrates the biochemical characterization of poly-ADP-ribosylation system, namely, reaction product, i.e., poly-ADP-ribose, and acceptor proteins, in the O. vulgaris brain. Immunochemical analyses evidenced that the sole poly-ADP-ribose acceptor was the octopus cytoskeleton 50-kDa actin. It was present in both free, endogenously poly-ADP-ribosylated form (70kDa) and in complex with V-poly-ADP-ribose polymerase and poly-ADP-ribose (260kDa). The components of this complex, alkali and high salt sensitive, were purified and characterized. The kind and the length of poly-ADP-ribose corresponded to linear chains of 30-35 ADP-ribose units, in accordance with the features of the polymer synthesized by the known vault-poly-ADP-ribose polymerase. In vitro experiments showed that V-poly-ADP-ribose polymerase activity of brain cytoplasmic fraction containing endogenous actin increased upon the addition of commercial actin and was highly reduced by ATP. Anti-actin immunoblot of the mixture in the presence and absence of ATP showed that the poly-ADP-ribosylation of octopus actin is a dynamic process balanced by the ATP-dependent polymerization of the cytoskeleton protein, a fundamental mechanism for synaptic plasticity.
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Affiliation(s)
- Anna De Maio
- Biochemistry, Department of Biology, University of Naples Federico II, 80126, Naples, Italy
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Rahn EJ, Guzman-Karlsson MC, David Sweatt J. Cellular, molecular, and epigenetic mechanisms in non-associative conditioning: implications for pain and memory. Neurobiol Learn Mem 2013; 105:133-50. [PMID: 23796633 DOI: 10.1016/j.nlm.2013.06.008] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 06/10/2013] [Accepted: 06/11/2013] [Indexed: 01/09/2023]
Abstract
Sensitization is a form of non-associative conditioning in which amplification of behavioral responses can occur following presentation of an aversive or noxious stimulus. Understanding the cellular and molecular underpinnings of sensitization has been an overarching theme spanning the field of learning and memory as well as that of pain research. In this review we examine how sensitization, both in the context of learning as well as pain processing, shares evolutionarily conserved behavioral, cellular/synaptic, and epigenetic mechanisms across phyla. First, we characterize the behavioral phenomenon of sensitization both in invertebrates and vertebrates. Particular emphasis is placed on long-term sensitization (LTS) of withdrawal reflexes in Aplysia following aversive stimulation or injury, although additional invertebrate models are also covered. In the context of vertebrates, sensitization of mammalian hyperarousal in a model of post-traumatic stress disorder (PTSD), as well as mammalian models of inflammatory and neuropathic pain is characterized. Second, we investigate the cellular and synaptic mechanisms underlying these behaviors. We focus our discussion on serotonin-mediated long-term facilitation (LTF) and axotomy-mediated long-term hyperexcitability (LTH) in reduced Aplysia systems, as well as mammalian spinal plasticity mechanisms of central sensitization. Third, we explore recent evidence implicating epigenetic mechanisms in learning- and pain-related sensitization. This review illustrates the fundamental and functional overlay of the learning and memory field with the pain field which argues for homologous persistent plasticity mechanisms in response to sensitizing stimuli or injury across phyla.
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Affiliation(s)
- Elizabeth J Rahn
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
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Long term potentiation affects intracellular metalloproteinases activity in the mossy fiber-CA3 pathway. Mol Cell Neurosci 2012; 50:147-59. [PMID: 22555058 DOI: 10.1016/j.mcn.2012.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 04/06/2012] [Accepted: 04/13/2012] [Indexed: 01/08/2023] Open
Abstract
Matrix Metalloproteinases (MMPs) are a family of endopeptidases known to process extracellular proteins. In the last decade, studies carried out mainly on the Schaffer collateral-CA1 hippocampal projection have provided solid evidence that MMPs regulate synaptic plasticity and learning. Recently, our group has shown that MMP blockade disrupts LTP maintenance also in the mossy fiber-CA3 (mf-CA3) projection (Wojtowicz and Mozrzymas, 2010), where LTP mechanisms are profoundly different (NMDAR-independent and presynaptic expression site). However, how plasticity of this pathway correlates with activity and expression of MMPs remains unknown. Interestingly, several potential MMP substrates (especially of gelatinases) are localized intracellularly but little is known about MMP activity in this compartment. In the present study we have asked whether LTP is associated with the expression and activity of gelatinases in apparent intra- and extracellular compartments along mf-CA3 projection. In situ zymography showed that LTP induction was associated with increased gelatinases activity in the cytoplasm of the hilar and CA3 neurons. Using gelatin zymography, immunohistochemistry and immunofluorescent staining we found that this effect was due to de novo synthesis and activation of MMP-9 which, 2-3h after LTP induction was particularly evident in the cytoplasm. In contrast, MMP-2 was localized preferentially in the nuclei and was not affected by LTP induction. In conclusion, we demonstrate that LTP induction in the mf-CA3 pathway correlates with increased expression and activity of MMP-9 and provide the first evidence that this increase is particularly evident in the neuronal cytoplasm and nucleus.
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Plane JM, Grossenbacher SK, Deng W. PARP-1 deletion promotes subventricular zone neural stem cells toward a glial fate. J Neurosci Res 2012; 90:1489-506. [PMID: 22431411 DOI: 10.1002/jnr.23040] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 01/12/2012] [Accepted: 01/15/2012] [Indexed: 01/05/2023]
Abstract
Identification of critical factors involved in oligodendroglial fate specification from endogenous neural stem cells is relevant to the development of therapeutic interventions that aim to promote remyelination. Here we report a novel role of the DNA repair protein poly-ADP-ribose polymerase-1 (PARP-1) in regulating the neural stem cell profile in the postnatal mouse forebrain subventricular zone (SVZ). We observed increased expression of Sox2 and Sox10 in the SVZ of postnatal day 11 (P11) PARP-1 knockout mice. This increase corresponded to increased Olig2 expression in Sox2-positive cells of the PARP-1 knockout mouse SVZ and decreased Map2abc expression compared with Sox2/Olig2 and Sox2/Map2abc expression in wild-type mice. We noted enhanced expression of proliferating oligodendrocyte progenitor cells (OPCs) at the expense of proliferating neuroblasts in the SVZ of PARP-1 knockout mice, by using Olig1/Ki67/DCX, NG2/Ki67/DCX, and PDGFR/BrdU/TuJ1 immunofluorescence labeling. In addition, the percentage of BrdU/Olig2 double-labeled cells increased in the SVZ and corpus callosum of PARP-1 knockout mice compared with wild-type mice. We also observed a decrease in DCX-positive cells without a decrease in the overall SVZ area in PARP-1 knockout mice, further indicating a switch from neuroblast to OPC fate. PARP-1 knockout mice displayed thinning of MBP expression in the corpus callosum and external capsule, suggesting that the enhanced OPC proliferation in the SVZ might compensate for deficiency in myelination. Together, our results show that PARP-1 deletion promotes SVZ neural stem cells toward a glial fate and suggest that future studies target PARP-1 as a potential therapeutic strategy for demyelinating diseases.
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Affiliation(s)
- Jennifer M Plane
- Department of Biochemistry and Molecular Medicine, Institute for Pediatric Regenerative Medicine, School of Medicine, University of California, Davis, Sacramento, California 95817, USA
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Day JJ, Sweatt JD. Epigenetic treatments for cognitive impairments. Neuropsychopharmacology 2012; 37:247-60. [PMID: 21593731 PMCID: PMC3238093 DOI: 10.1038/npp.2011.85] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 12/11/2022]
Abstract
Epigenetic mechanisms integrate signals from diverse intracellular transduction cascades and in turn regulate genetic readout. Accumulating evidence has revealed that these mechanisms are critical components of ongoing physiology and function in the adult nervous system, and are essential for many cognitive processes, including learning and memory. Moreover, a number of psychiatric disorders and syndromes that involve cognitive impairments are associated with altered epigenetic function. In this review, we will examine how epigenetic mechanisms contribute to cognition, consider how changes in these mechanisms may lead to cognitive impairments in a range of disorders and discuss the potential utility of therapeutic treatments that target epigenetic machinery. Finally, we will comment on a number of caveats associated with interpreting epigenetic changes and using epigenetic treatments, and suggest future directions for research in this area that will expand our understanding of the epigenetic changes underlying cognitive disorders.
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Affiliation(s)
- Jeremy J Day
- Department of Neurobiology and Evelyn F McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA.
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Briggs AG, Bent AF. Poly(ADP-ribosyl)ation in plants. TRENDS IN PLANT SCIENCE 2011; 16:372-80. [PMID: 21482174 DOI: 10.1016/j.tplants.2011.03.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2010] [Revised: 03/07/2011] [Accepted: 03/09/2011] [Indexed: 05/03/2023]
Abstract
Poly(ADP-ribose) polymerases (PARPs) and poly(ADP-ribose) glycohydrolases (PARGs) are the main enzymes responsible for the post-translational modification known as poly(ADP-ribosyl)ation. These enzymes play important roles in genotoxic stress tolerance and DNA repair, programmed cell death, transcription, and cell cycle control in animals. Similar impacts are being discovered in plants, as well as roles in plant-specific processes. In particular, we review recent work that has revealed significant roles for poly(ADP-ribosyl)ation in plant responses to biotic and abiotic stress, as well as roles for ADP-ribose pyrophosphatases (a subset of the nucleoside diphosphate linked to some moiety-X or NUDX hydrolases). Future challenges include identification of poly(ADP-ribosyl)ation targets and interacting proteins, improved use of inhibitors and plant mutants, and field-based studies with economically valuable plant species.
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Affiliation(s)
- Amy G Briggs
- Program in Cellular and Molecular Biology, University of Wisconsin - Madison, WI, USA
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Chaitanya GV, Alexander JS, Babu PP. PARP-1 cleavage fragments: signatures of cell-death proteases in neurodegeneration. Cell Commun Signal 2010; 8:31. [PMID: 21176168 PMCID: PMC3022541 DOI: 10.1186/1478-811x-8-31] [Citation(s) in RCA: 653] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 12/22/2010] [Indexed: 11/16/2022] Open
Abstract
The normal function of poly (ADP-ribose) polymerase-1 (PARP-1) is the routine repair of DNA damage by adding poly (ADP ribose) polymers in response to a variety of cellular stresses. Recently, it has become widely appreciated that PARP-1 also participates in diverse physiological and pathological functions from cell survival to several forms of cell death and has been implicated in gene transcription, immune responses, inflammation, learning, memory, synaptic functions, angiogenesis and aging. In the CNS, PARP inhibition attenuates injury in pathologies like cerebral ischemia, trauma and excitotoxicity demonstrating a central role of PARP-1 in these pathologies. PARP-1 is also a preferred substrate for several 'suicidal' proteases and the proteolytic action of suicidal proteases (caspases, calpains, cathepsins, granzymes and matrix metalloproteinases (MMPs)) on PARP-1 produces several specific proteolytic cleavage fragments with different molecular weights. These PARP-1 signature fragments are recognized biomarkers for specific patterns of protease activity in unique cell death programs. This review focuses on specific suicidal proteases active towards PARP-1 to generate signature PARP-1 fragments that can identify key proteases and particular forms of cell death involved in pathophysiology. The roles played by some of the PARP-1 fragments and their associated binding partners in the control of different forms of cell death are also discussed.
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Affiliation(s)
- Ganta Vijay Chaitanya
- Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad, India
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Louisiana-USA
| | - Jonathan S Alexander
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center-Shreveport, Louisiana-USA
| | - Phanithi Prakash Babu
- Department of Biotechnology, School of Life Sciences, University of Hyderabad, Hyderabad, India
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Sun Y, Monje FJ, Pollak DD, Lubec G. A first partial Aplysia californica proteome. Amino Acids 2010; 41:955-68. [PMID: 21069399 DOI: 10.1007/s00726-010-0795-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 10/20/2010] [Indexed: 11/28/2022]
Abstract
Aplysia proteins have not been studied systematically and it was therefore the aim of the study to carry out protein profiling in ganglia from Aplysia californica (AC). AC ganglia were extirpated, proteins extracted and run on 2DE with subsequent in-gel digestion, followed by identification of proteins by nano-LC-ESI-MS/MS on an ion trap. Proteins were identified based upon a public Aplysia EST database. Out of 408 picked spots, 276 spots were identified corresponding to 172 ESTs and 118 individual proteins. The range of sequence coverage was between 14 and 80% and the average amount of peptides used for the identification of proteins was 9 (from 3 to 24). Mean score for protein identification was 516. Comparison of protein levels between cerebral, pleural, pedal and abdominal ganglia revealed a series of significant differences including: signaling, metabolism, cytoskeleton and structural, redox, chaperone, replication/transcription and electron/proton transport proteins. The generation of a protein map complements transcriptional studies carried out in AC ganglia. The findings provide the basis for investigation into post-translational modifications, splice variants and assist in the generation of antibodies against AC proteins. Moreover, differences in protein expression between ganglia may be valuable for the design of future studies in neurobiology of AC.
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Affiliation(s)
- Yanwei Sun
- Department of Pediatrics, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria
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Histone H1 poly[ADP]-ribosylation regulates the chromatin alterations required for learning consolidation. J Neurosci 2010; 30:13305-13. [PMID: 20926656 DOI: 10.1523/jneurosci.3010-10.2010] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Memory formation requires changes in gene expression, which are regulated by the activation of transcription factors and by changes in epigenetic factors. Poly[ADP]-ribosylation of nuclear proteins has been postulated as a chromatin modification involved in memory consolidation, although the mechanisms involved are not well characterized. Here we demonstrate that poly[ADP]-ribose polymerase 1 (PARP-1) activity and the poly[ADP]-ribosylation of proteins over a specific time course is required for the changes in synaptic plasticity related to memory stabilization in mice. At the molecular level, histone H1 poly[ADP]-ribosylation was evident in the hippocampus after the acquisition period, and it was selectively released in a PARP-1-dependent manner at the promoters of cAMP response element-binding protein and nuclear factor-κB dependent genes associated with learning and memory. These findings suggest that histone H1 poly[ADP]-ribosylation, and its loss at specific loci, is an epigenetic mechanism involved in the reprogramming of neuronal gene expression required for memory consolidation.
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Adams-Phillips L, Briggs AG, Bent AF. Disruption of poly(ADP-ribosyl)ation mechanisms alters responses of Arabidopsis to biotic stress. PLANT PHYSIOLOGY 2010; 152:267-80. [PMID: 19889874 PMCID: PMC2799362 DOI: 10.1104/pp.109.148049] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 10/30/2009] [Indexed: 05/03/2023]
Abstract
Poly(ADP-ribosyl)ation is a posttranslational protein modification in which ADP-ribose (ADP-Rib) units derived from NAD(+) are attached to proteins by poly(ADP-Rib) polymerase (PARP) enzymes. ADP-Rib groups are removed from these polymer chains by the enzyme poly(ADP-Rib) glycohydrolase (PARG). In animals, poly(ADP-ribosyl)ation is associated with DNA damage responses and programmed cell death. Previously, we hypothesized a role for poly(ADP-ribosyl)ation in plant defense responses when we detected defense-associated expression of the poly(ADP-ribosyl)ation-related genes PARG2 and NUDT7 and observed altered callose deposition in the presence of a chemical PARP inhibitor. The role of poly(ADP-ribosyl)ation in plant defenses was more extensively investigated in this study, using Arabidopsis (Arabidopsis thaliana). Pharmacological inhibition of PARP using 3-aminobenzamide perturbs certain innate immune responses to microbe-associated molecular patterns (flg22 and elf18), including callose deposition, lignin deposition, pigment accumulation, and phenylalanine ammonia lyase activity, but does not disrupt other responses, such as the initial oxidative burst and expression of some early defense-associated genes. Mutant parg1 seedlings exhibit exaggerated seedling growth inhibition and pigment accumulation in response to elf18 and are hypersensitive to the DNA-damaging agent mitomycin C. Both parg1 and parg2 knockout plants show accelerated onset of disease symptoms when infected with Botrytis cinerea. Cellular levels of ADP-Rib polymer increase after infection with avirulent Pseudomonas syringae pv tomato DC3000 avrRpt2(+), and pathogen-dependent changes in the poly(ADP-ribosyl)ation of discrete proteins were also observed. We conclude that poly(ADP-ribosyl)ation is a functional component in plant responses to biotic stress.
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Affiliation(s)
| | | | - Andrew F. Bent
- Department of Plant Pathology (L.A.-P., A.G.B., A.F.B.) and Program in Cellular and Molecular Biology (A.G.B.), University of Wisconsin, Madison, Wisconsin 53706
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