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Andrabi SM, Sharma NS, Karan A, Shahriar SMS, Cordon B, Ma B, Xie J. Nitric Oxide: Physiological Functions, Delivery, and Biomedical Applications. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303259. [PMID: 37632708 PMCID: PMC10602574 DOI: 10.1002/advs.202303259] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Indexed: 08/28/2023]
Abstract
Nitric oxide (NO) is a gaseous molecule that has a central role in signaling pathways involved in numerous physiological processes (e.g., vasodilation, neurotransmission, inflammation, apoptosis, and tumor growth). Due to its gaseous form, NO has a short half-life, and its physiology role is concentration dependent, often restricting its function to a target site. Providing NO from an external source is beneficial in promoting cellular functions and treatment of different pathological conditions. Hence, the multifaceted role of NO in physiology and pathology has garnered massive interest in developing strategies to deliver exogenous NO for the treatment of various regenerative and biomedical complexities. NO-releasing platforms or donors capable of delivering NO in a controlled and sustained manner to target tissues or organs have advanced in the past few decades. This review article discusses in detail the generation of NO via the enzymatic functions of NO synthase as well as from NO donors and the multiple biological and pathological processes that NO modulates. The methods for incorporating of NO donors into diverse biomaterials including physical, chemical, or supramolecular techniques are summarized. Then, these NO-releasing platforms are highlighted in terms of advancing treatment strategies for various medical problems.
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Affiliation(s)
- Syed Muntazir Andrabi
- Department of Surgery‐Transplant and Mary & Dick Holland Regenerative Medicine ProgramCollege of MedicineUniversity of Nebraska Medical CenterOmahaNE68198USA
| | - Navatha Shree Sharma
- Department of Surgery‐Transplant and Mary & Dick Holland Regenerative Medicine ProgramCollege of MedicineUniversity of Nebraska Medical CenterOmahaNE68198USA
| | - Anik Karan
- Department of Surgery‐Transplant and Mary & Dick Holland Regenerative Medicine ProgramCollege of MedicineUniversity of Nebraska Medical CenterOmahaNE68198USA
| | - S. M. Shatil Shahriar
- Department of Surgery‐Transplant and Mary & Dick Holland Regenerative Medicine ProgramCollege of MedicineUniversity of Nebraska Medical CenterOmahaNE68198USA
| | - Brent Cordon
- Department of Surgery‐Transplant and Mary & Dick Holland Regenerative Medicine ProgramCollege of MedicineUniversity of Nebraska Medical CenterOmahaNE68198USA
| | - Bing Ma
- Cell Therapy Manufacturing FacilityMedStar Georgetown University HospitalWashington, DC2007USA
| | - Jingwei Xie
- Department of Surgery‐Transplant and Mary & Dick Holland Regenerative Medicine ProgramCollege of MedicineUniversity of Nebraska Medical CenterOmahaNE68198USA
- Department of Mechanical and Materials EngineeringCollege of EngineeringUniversity of Nebraska LincolnLincolnNE68588USA
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Rossato JI, Radiske A, Gonzalez MC, Apolinário G, de Araújo RL, Bevilaqua LR, Cammarota M. NMDARs control object recognition memory destabilization and reconsolidation. Brain Res Bull 2023; 197:42-48. [PMID: 37011815 DOI: 10.1016/j.brainresbull.2023.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 04/04/2023]
Abstract
Object recognition memory (ORM) allows identification of previously encountered items and is therefore crucial for remembering episodic information. In rodents, reactivation during recall in the presence of a novel object destabilizes ORM and initiates a Zif268 and protein synthesis-dependent reconsolidation process in the hippocampus that links the memory of this object to the reactivated recognition trace. Hippocampal NMDA receptors (NMDARs) modulate Zif268 expression and protein synthesis and regulate memory stability but their possible involvement in the ORM destabilization/reconsolidation cycle has yet to be analyzed in detail. We found that, in adult male Wistar rats, intra dorsal-CA1 administration of the non-subunit selective NMDAR antagonist AP5, or of the GluN2A subunit-containing NMDAR antagonist TCN201, 5min after an ORM reactivation session in the presence of a novel object carried out 24h post-training impaired retention 24h later. In contrast, pre-reactivation administration of the GluN2B subunit-containing NMDAR antagonist RO25-6981 had no effect on ORM recall or retention but impeded the amnesia caused by Zif268 silencing and protein synthesis inhibition in dorsal CA1. Our results indicate that GluN2B-containing hippocampal NMDARs are necessary for ORM destabilization whereas GluN2A-containing NMDARs are involved in ORM reconsolidation, and suggest that modulation of the relative activity of these receptor subtypes during recall regulates ORM persistence.
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Rossato JI, Radiske A, Gonzalez MC, Bevilaqua LRM, Cammarota M. On the effect of hippocampal c-Jun N-terminal kinase inhibition on object recognition memory. Front Behav Neurosci 2022; 16:1052124. [PMID: 36578877 PMCID: PMC9790984 DOI: 10.3389/fnbeh.2022.1052124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/22/2022] [Indexed: 12/14/2022] Open
Abstract
c-Jun N-terminal kinase (JNK) phosphorylates the transcription factor c-Jun in response to stress stimuli and contributes to both hippocampal synaptic plasticity and memory processing in mammals. Object recognition memory (ORM) is essential for remembering facts and events. In rodents, ORM consolidation and reconsolidation require a functional hippocampus. However, the possible involvement of hippocampal JNK on ORM processing has not yet been studied. Here we show that when injected into dorsal CA1 5 min, but not 6 h, after training adult male rats in the novel object recognition learning task, the JNK inhibitor SP600125 impaired ORM for at least 7 days without affecting exploratory activity, short-term ORM retention, or the functional integrity of the hippocampus. SP600125 did not hinder ORM retention when given in CA1 after a memory reactivation session carried out 24 h post-training in the presence of the same two objects presented during the training session, but caused time-dependent amnesia when one of the objects presented at training was replaced by a different but behaviorally equivalent novel one. Taken together, our results indicate that hippocampal JNK activity is necessary for ORM consolidation and reconsolidation but not for ORM recall or short-term retention.
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Affiliation(s)
- Janine I. Rossato
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil,Department of Physiology, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Andressa Radiske
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil,Edmond and Lily Safra International Institute of Neuroscience, Macaíba, Rio Grande do Norte, Brazil
| | - Maria Carolina Gonzalez
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil,Edmond and Lily Safra International Institute of Neuroscience, Macaíba, Rio Grande do Norte, Brazil
| | - Lia R. M. Bevilaqua
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | - Martín Cammarota
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil,*Correspondence: Martín Cammarota,
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Gonzalez MC, Radiske A, Rossato JI, Conde-Ocazionez S, Bevilaqua LRM, Cammarota M. Optogenetic inactivation of the medial septum impairs long-term object recognition memory formation. Mol Brain 2022; 15:50. [PMID: 35672792 PMCID: PMC9172102 DOI: 10.1186/s13041-022-00938-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/24/2022] [Indexed: 11/23/2022] Open
Abstract
Theta is one of the most prominent extracellular synchronous oscillations in the mammalian brain. Hippocampal theta relies on an intact medial septum (MS) and has been consistently recorded during the training phase of some learning paradigms, suggesting that it may be implicated in hippocampus-dependent long-term memory processing. Object recognition memory (ORM) allows animals to identify familiar items and is essential for remembering facts and events. In rodents, long-term ORM formation requires a functional hippocampus but the involvement of the MS in this process remains controversial. We found that training adult male Wistar rats in a long-term ORM-inducing learning task involving exposure to two different, but behaviorally equivalent novel stimuli objects increased hippocampal theta power, and that suppressing theta via optogenetic MS inactivation caused amnesia. Importantly, the amnesia was specific to the object the animals were exploring when the MS was inactivated. Taken together, our results indicate that the MS is necessary for long-term ORM formation and suggest that hippocampal theta activity is causally linked to this process.
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Gonzalez MC, Radiske A, Conde-Ocazionez S, Rossato JI, Bevilaqua LR, Cammarota M. Reactivation-dependent amnesia for object recognition memory is contingent on hippocampal theta-gamma coupling during recall. Learn Mem 2022; 29:1-6. [PMID: 34911798 PMCID: PMC8686592 DOI: 10.1101/lm.053482.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/25/2021] [Indexed: 01/03/2023]
Abstract
Hippocampal dopamine D1/D5 receptor-dependent destabilization is necessary for object recognition memory (ORM) updating through reconsolidation. Dopamine also regulates hippocampal theta and gamma oscillations, which are involved in novelty and memory processing. We found that, in adult male rats, ORM recall in the presence of a novel object, but not in the presence of a familiar one, triggers hippocampal theta-gamma coupling. Hippocampal theta-gamma coupling (hPAC) does not happen when ORM destabilization is prevented by blocking D1/D5 receptors, but artificial hPAC generation during recall in the presence of a familiar object enables the amnesic effect of reconsolidation inhibitors. Therefore, hPAC controls ORM destabilization, and its modulation could increase reconsolidation-based psychotherapy efficacy.
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Affiliation(s)
- Maria Carolina Gonzalez
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal 59076-550, Brazil,Edmond and Lily Safra International Institute of Neuroscience, Natal 59280-000, Brazil
| | - Andressa Radiske
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal 59076-550, Brazil
| | | | - Janine I. Rossato
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal 59076-550, Brazil,Department of Physiology, Federal University of Rio Grande do Norte, Natal 59064-741, Brazil
| | - Lia R.M. Bevilaqua
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal 59076-550, Brazil
| | - Martín Cammarota
- Memory Research Laboratory, Brain Institute, Federal University of Rio Grande do Norte, Natal 59076-550, Brazil
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Rapid ATF4 Depletion Resets Synaptic Responsiveness after cLTP. eNeuro 2021; 8:ENEURO.0239-20.2021. [PMID: 33980608 PMCID: PMC8177969 DOI: 10.1523/eneuro.0239-20.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 04/14/2021] [Accepted: 04/24/2021] [Indexed: 12/14/2022] Open
Abstract
Activating transcription factor 4 [ATF4 (also called CREB2)], in addition to its well studied role in stress responses, is proposed to play important physiologic functions in regulating learning and memory. However, the nature of these functions has not been well defined and is subject to apparently disparate views. Here, we provide evidence that ATF4 is a regulator of excitability during synaptic plasticity. We evaluated the role of ATF4 in mature hippocampal cultures subjected to a brief chemically induced LTP (cLTP) protocol that results in changes in mEPSC properties and synaptic AMPA receptor density 1 h later, with return to baseline by 24 h. We find that ATF4 protein, but not its mRNA, is rapidly depleted by ∼50% in response to cLTP induction via NMDA receptor activation. Depletion is detectable in dendrites within 15 min and in cell bodies by 1 h, and returns to baseline by 8 h. Such changes correlate with a parallel depletion of phospho-eIF2a, suggesting that ATF4 loss is driven by decreased translation. To probe the physiologic role of cLTP-induced ATF4 depletion, we constitutively overexpressed the protein. Reversing ATF4 depletion by overexpression blocked the recovery of synaptic activity and AMPA receptor density to baseline values that would otherwise occur 24 h after cLTP induction. This reversal was not reproduced by a transcriptionally inactive ATF4 mutant. These findings support the role of ATF4 as a required element in resetting baseline synaptic responsiveness after cLTP.
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Koncha RR, Ramachandran G, Sepuri NBV, Ramaiah KVA. CCCP-induced mitochondrial dysfunction - characterization and analysis of integrated stress response to cellular signaling and homeostasis. FEBS J 2021; 288:5737-5754. [PMID: 33837631 DOI: 10.1111/febs.15868] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/26/2021] [Accepted: 04/07/2021] [Indexed: 12/11/2022]
Abstract
Mitochondrial dysfunction mediated by CCCP (carbonyl cyanide m-chlorophenyl hydrazone), an inhibitor of mitochondrial oxidative phosphorylation, evokes the integrated stress response (ISR), which is analyzed here by eIF2α phosphorylation and expression profiles of ATF4 and CHOP proteins. Our findings suggest that the CCCP-induced ISR pathway is mediated by activation of HRI kinase, but not by GCN2, PERK, or PKR. Also, CCCP activates AMPK, a cellular energy sensor, and AKT, a regulator implicated in cell survival, and suppresses phosphorylation of mTORC1 substrates eIF4E-BP1 and S6K. CCCP also downregulates translation and promotes autophagy, leading to noncaspase-mediated cell death in HepG2 cells. All these events are neutralized by NAC, an anti-ROS, suggesting that CCCP-induced mitochondrial dysfunction promotes oxidative stress. ISRIB, an inhibitor of the ISR pathway, mitigates CCCP-induced expression of ATF4 and CHOP, activation of AKT, and autophagy, similar to NAC. However, it fails to reverse CCCP-induced AMPK activation, suggesting that CCCP-induced autophagy is dependent on ISR and independent of AMPK activation. ISRIB restores partly, inhibition in eIF4E-BP1 phosphorylation, promotes eIF2α phosphorylation, albeit slowly, and mitigates suppression of translation accordingly, in CCCP-treated cells. These findings are consistent with the idea that CCCP-induced oxidative stress leading to eIF2α phosphorylation and ATF4 expression, which is known to stimulate genes involved in autophagy, play a pro-survival role together with AKT activation and regulate mTOR-mediated eIF4E-BP1 phosphorylation.
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Affiliation(s)
| | - Gayatri Ramachandran
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, India
| | - Naresh Babu V Sepuri
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, India
| | - Kolluru V A Ramaiah
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, India
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Ramos-Fernández E, Arrázola MS, Oliva CA, Arredondo SB, Varela-Nallar L, Inestrosa NC. Wnt5a promotes hippocampal postsynaptic development and GluN2B-induced expression via the eIF2α HRI kinase. Sci Rep 2021; 11:7395. [PMID: 33795747 PMCID: PMC8016897 DOI: 10.1038/s41598-021-86708-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/18/2021] [Indexed: 12/30/2022] Open
Abstract
Wnt signaling plays a key role in neurodevelopment and neuronal maturation. Specifically, Wnt5a stimulates postsynaptic assemblies, increases glutamatergic neurotransmission and, through calcium signaling, generates nitric oxide (NO). Trying to unveil the molecular pathway triggering these postsynaptic effects, we found that Wnt5a treatment induces a time-dependent increases in the length of the postsynaptic density (PSD), elicits novel synaptic contacts and facilitates F-actin flow both in in vitro and ex vivo models. These effects were partially abolished by the inhibition of the Heme-regulated eukaryotic initiation factor 2α (HRI) kinase, a kinase which phosphorylates the initiation translational factor eIF2α. When phosphorylated, eIF2α normally avoids the translation of proteins not needed during stress conditions, in order to avoid unnecessary energetic expenses. However, phosphorylated eIF2α promotes the translation of some proteins with more than one open reading frame in its 5′ untranslated region. One of these proteins targeted by Wnt-HRI-eIF2α mediated translation is the GluN2B subunit of the NMDA receptor. The identified increase in GluN2B expression correlated with increased NMDA receptor function. Considering that NMDA receptors are crucial for excitatory synaptic transmission, the molecular pathway described here contributes to the understanding of the fast and plastic translational mechanisms activated during learning and memory processes.
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Affiliation(s)
- Eva Ramos-Fernández
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile. .,École polytechnique fédérale de Lausanne, Lausanne, Switzerland.
| | - Macarena S Arrázola
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile.,Centro de Biología Integrativa, Universidad Mayor, Santiago, Chile
| | - Carolina A Oliva
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile
| | - Sebastián B Arredondo
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile
| | - Lorena Varela-Nallar
- Instituto de Ciencias Biomédicas, Facultad de Medicina y Facultad de Ciencias de La Vida, Universidad Andrés Bello, Santiago, Chile
| | - Nibaldo C Inestrosa
- Centro de Envejecimiento y Regeneración (CARE UC), CARE UC Biomedical Center, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Alameda 340, 8331150, Santiago, Chile. .,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile.
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Amyloid Beta-Peptide Increases BACE1 Translation through the Phosphorylation of the Eukaryotic Initiation Factor-2 α. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:2739459. [PMID: 33014268 PMCID: PMC7525306 DOI: 10.1155/2020/2739459] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 12/02/2022]
Abstract
Alzheimer's disease (AD) is tightly linked to oxidative stress since amyloid beta-peptide (Aβ) aggregates generate free radicals. Moreover, the aggregation of Aβ is increased by oxidative stress, and the neurotoxicity induced by the oligomers and fibrils is in part mediated by free radicals. Interestingly, it has been reported that oxidative stress can also induce BACE1 transcription and expression. BACE1 is the key enzyme in the cleavage of the amyloid precursor protein to produce Aβ, and the expression of this enzyme has been previously shown to be enhanced in the brains of Alzheimer's patients. Here, we have found that BACE1 expression is increased in the hippocampi from AD patients at both the early (Braak stage II) and late (Braak stage VI) stages of the disease as studied by immunohistochemistry and western blot. To address the role of Aβ and oxidative stress in the regulation of BACE1 expression, we have analyzed the effect of subtoxic concentrations of Aβ oligomers (0.25 μM) and H2O2 (10 mM) on a human neuroblastoma cell line. Firstly, our results show that Aβ oligomers and H2O2 induce an increase of BACE1 mRNA as we studied by qPCR. Regarding BACE1 translation, it is dependent on the phosphorylation of the eukaryotic initiation factor 2α (eIF2α), since BACE1 mRNA bears a 5′UTR that avoids its translation under basal conditions. BACE1 5′UTR contains four upstream initiating codons (uAUGs), and its translation is activated when eIF2α is phosphorylated. Consistently, we have obtained that Aβ oligomers and H2O2 increase the levels of BACE1 and p-eIF2α assayed by western blot and confocal microscopy. Our results suggest that Aβ oligomers increase BACE1 translation by phosphorylating eIF2α in a process that involves oxidative stress and conforms a pathophysiological loop, where the Aβ once aggregated favors its own production continuously by the increase in BACE1 expression as observed in AD patients.
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Alvarez-Castelao B, Tom Dieck S, Fusco CM, Donlin-Asp P, Perez JD, Schuman EM. The switch-like expression of heme-regulated kinase 1 mediates neuronal proteostasis following proteasome inhibition. eLife 2020; 9:52714. [PMID: 32329716 PMCID: PMC7224698 DOI: 10.7554/elife.52714] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 04/20/2020] [Indexed: 12/20/2022] Open
Abstract
We examined the feedback between the major protein degradation pathway, the ubiquitin-proteasome system (UPS), and protein synthesis in rat and mouse neurons. When protein degradation was inhibited, we observed a coordinate dramatic reduction in nascent protein synthesis in neuronal cell bodies and dendrites. The mechanism for translation inhibition involved the phosphorylation of eIF2α, surprisingly mediated by eIF2α kinase 1, or heme-regulated kinase inhibitor (HRI). Under basal conditions, neuronal expression of HRI is barely detectable. Following proteasome inhibition, HRI protein levels increase owing to stabilization of HRI and enhanced translation, likely via the increased availability of tRNAs for its rare codons. Once expressed, HRI is constitutively active in neurons because endogenous heme levels are so low; HRI activity results in eIF2α phosphorylation and the resulting inhibition of translation. These data demonstrate a novel role for neuronal HRI that senses and responds to compromised function of the proteasome to restore proteostasis.
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Affiliation(s)
| | | | - Claudia M Fusco
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Paul Donlin-Asp
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Julio D Perez
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Erin M Schuman
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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Functions and dysfunctions of nitric oxide in brain. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1949-1967. [DOI: 10.1016/j.bbadis.2018.11.007] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/29/2018] [Accepted: 11/11/2018] [Indexed: 02/06/2023]
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Guix FX, Sartório CL, Ill-Raga G. BACE1 Translation: At the Crossroads Between Alzheimer's Disease Neurodegeneration and Memory Consolidation. J Alzheimers Dis Rep 2019; 3:113-148. [PMID: 31259308 PMCID: PMC6597968 DOI: 10.3233/adr-180089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Human life unfolds not only in time and space, but also in the recollection and interweaving of memories. Therefore, individual human identity depends fully on a proper access to the autobiographical memory. Such access is hindered under pathological conditions such as Alzheimer’s disease, which affects millions of people worldwide. Unfortunately, no effective cure exists to prevent this disorder, the impact of which will rise alarmingly within the next decades. While Alzheimer’s disease is largely considered to be the outcome of amyloid-β (Aβ) peptide accumulation in the brain, conceiving this complex disorder strictly as the result of Aβ-neurotoxicity is perhaps a too straight-line simplification. Instead, complementary to this view, the tableau of molecular disarrangements in the Alzheimer’s disease brain may be reflecting, at least in part, a loss of function phenotype in memory processing. Here we take BACE1 translation and degradation as a gateway to study molecular mechanisms putatively involved in the transition between memory and neurodegeneration. BACE1 participates in the excision of Aβ-peptide from its precursor holoprotein, but plays a role in synaptic plasticity too. Its translation is governed by eIF2α phosphorylation: a hub integrating cellular responses to stress, but also a critical switch in memory consolidation. Paralleling these dualities, the eIF2α-kinase HRI has been shown to be a nitric oxide-dependent physiological activator of hippocampal BACE1 translation. Finally, beholding BACE1 as a representative protease active in the CNS, we venture a new perspective on the cellular basis of memory, which may incorporate neurodegeneration in itself as a drift in memory consolidating systems.
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Affiliation(s)
- Francesc X Guix
- Department of Molecular Neuropathology, Centro de Biología Molecular Severo Ochoa-CSIC, Madrid, Spain
| | - Carmem L Sartório
- Division of Physiological Sciences, Federal University of Espírito Santo, Vitória, Espírito Santo, Brazil
| | - Gerard Ill-Raga
- Division of Physiological Sciences, Federal University of Espírito Santo, Vitória, Espírito Santo, Brazil
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The eIF2α Kinase Heme-Regulated Inhibitor Protects the Host from Infection by Regulating Intracellular Pathogen Trafficking. Infect Immun 2018; 86:IAI.00707-17. [PMID: 29311243 DOI: 10.1128/iai.00707-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 12/19/2017] [Indexed: 12/20/2022] Open
Abstract
The host employs both cell-autonomous and system-level responses to limit pathogen replication in the initial stages of infection. Previously, we reported that the eukaryotic initiation factor 2α (eIF2α) kinases heme-regulated inhibitor (HRI) and protein kinase R (PKR) control distinct cellular and immune-related activities in response to diverse bacterial pathogens. Specifically for Listeria monocytogenes, there was reduced translocation of the pathogen to the cytosolic compartment in HRI-deficient cells and consequently reduced loading of pathogen-derived antigens on major histocompatibility complex class I (MHC-I) complexes. Here we show that Hri-/- mice, as well as wild-type mice treated with an HRI inhibitor, are more susceptible to listeriosis. In the first few hours of L. monocytogenes infection, there was much greater pathogen proliferation in the liver of Hri-/- mice than in the liver of Hri+/+ mice. Further, there was a rapid increase of serum interleukin-6 (IL-6) levels in Hri+/+ mice in the first few hours of infection whereas the increase in IL-6 levels in Hri-/- mice was notably delayed. Consistent with these in vivo findings, the rate of listeriolysin O (LLO)-dependent pathogen efflux from infected Hri-/- macrophages and fibroblasts was significantly higher than the rate seen with infected Hri+/+ cells. Treatment of cells with an eIF2α kinase activator enhanced both the HRI-dependent and PKR-dependent infection phenotypes, further indicating the pharmacologically malleability of this signaling pathway. Collectively, these results suggest that HRI mediates the cellular confinement and killing of virulent L. monocytogenes in addition to promoting a system-level cytokine response and that both are required to limit pathogen replication during the first few hours of infection.
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Activating Transcription Factor 4 (ATF4) modulates Rho GTPase levels and function via regulation of RhoGDIα. Sci Rep 2016; 6:36952. [PMID: 27841340 PMCID: PMC5107905 DOI: 10.1038/srep36952] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/21/2016] [Indexed: 01/21/2023] Open
Abstract
In earlier studies, we showed that ATF4 down-regulation affects post-synaptic development and dendritic spine morphology in neurons through increased turnover of the Rho GTPase Cell Division Cycle 42 (Cdc42) protein. Here, we find that ATF4 down-regulation in both hippocampal and cortical neuron cultures reduces protein and message levels of RhoGDIα, a stabilizer of the Rho GTPases including Cdc42. This effect is rescued by an shATF4-resistant active form of ATF4, but not by a mutant that lacks transcriptional activity. This is, at least in part, due to the fact that Arhgdia, the gene encoding RhoGDIα, is a direct transcriptional target of ATF4 as is shown in ChIP assays. This pathway is not restricted to neurons. This is seen in an impairment of cell migration on ATF4 reduction in non-neuronal cells. In conclusion, we have identified a new cellular pathway in which ATF4 regulates the expression of RhoGDIα that in turn affects Rho GTPase protein levels, and thereby, controls cellular functions as diverse as memory and cell motility.
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Ramos-Fernández E, Tajes M, ILL-Raga G, Vargas L, Busquets-García A, Bosch-Morató M, Guivernau B, Valls-Comamala V, Gomis M, Grau C, Fandos C, Rosen MD, Rabinowitz MH, Inestrosa N, Maldonado R, Altafaj X, Ozaita A, Alvarez A, Vicente R, Valverde MA, Muñoz FJ. Glutamatergic stimulation induces GluN2B translation by the nitric oxide-Heme-Regulated eIF2α kinase in cortical neurons. Oncotarget 2016; 7:58876-58892. [PMID: 27557499 PMCID: PMC5312282 DOI: 10.18632/oncotarget.11417] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 08/13/2016] [Indexed: 02/06/2023] Open
Abstract
The activation of N-Methyl D-Aspartate Receptor (NMDAR) by glutamate is crucial in the nervous system function, particularly in memory and learning. NMDAR is composed by two GluN1 and two GluN2 subunits. GluN2B has been reported to participate in the prevalent NMDAR subtype at synapses, the GluN1/2A/2B. Here we studied the regulation of GluN2B expression in cortical neurons finding that glutamate up-regulates GluN2B translation through the action of nitric oxide (NO), which induces the phosphorylation of the eukaryotic translation initiation factor 2 α (eIF2α). It is a process mediated by the NO-heme-regulated eIF2α kinase (HRI), as the effect was avoided when a specific HRI inhibitor or a HRI small interfering RNA (siHRI) were used. We found that the expressed GluN2B co-localizes with PSD-95 at the postsynaptic ending, which strengthen the physiological relevance of the proposed mechanism. Moreover the receptors bearing GluN2B subunits upon NO stimulation are functional as high Ca2+ entry was measured and increases the co-localization between GluN2B and GluN1 subunits. In addition, the injection of the specific HRI inhibitor in mice produces a decrease in memory retrieval as tested by the Novel Object Recognition performance. Summarizing our data suggests that glutamatergic stimulation induces HRI activation by NO to trigger GluN2B expression and this process would be relevant to maintain postsynaptic activity in cortical neurons.
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Affiliation(s)
- Eva Ramos-Fernández
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Marta Tajes
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Gerard ILL-Raga
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Lina Vargas
- Cell Signaling Laboratory, Department of Cellular and Molecular Biology, Faculty of Biological Science, Pontificia Universidad Católica, Santiago, Chile
| | - Arnau Busquets-García
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Mònica Bosch-Morató
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Biuse Guivernau
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Victòria Valls-Comamala
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Maria Gomis
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Cristina Grau
- Bellvitge Biomedical Research Institute, Unit of Neuropharmacology and Pain, University of Barcelona, Barcelona, Spain
| | - César Fandos
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Mark D. Rosen
- Janssen Research and Development, L.L.C., San Diego, CA, United States of America
| | | | - Nibaldo Inestrosa
- CARE, Department of Cellular and Molecular Biology, Faculty of Biological Science, Pontificia Universidad Católica, Santiago, Chile
| | - Rafael Maldonado
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Xavier Altafaj
- Bellvitge Biomedical Research Institute, Unit of Neuropharmacology and Pain, University of Barcelona, Barcelona, Spain
| | - Andrés Ozaita
- Neuropharmacology Laboratory, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Alejandra Alvarez
- Cell Signaling Laboratory, Department of Cellular and Molecular Biology, Faculty of Biological Science, Pontificia Universidad Católica, Santiago, Chile
| | - Rubén Vicente
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Miguel A. Valverde
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
| | - Francisco J. Muñoz
- Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain
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16
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Bellato HM, Hajj GNM. Translational control by eIF2α in neurons: Beyond the stress response. Cytoskeleton (Hoboken) 2016; 73:551-565. [PMID: 26994324 DOI: 10.1002/cm.21294] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 03/14/2016] [Accepted: 03/14/2016] [Indexed: 12/21/2022]
Abstract
The translation of mRNAs is a tightly controlled process that responds to multiple signaling pathways. In neurons, this control is also exerted locally due to the differential necessity of proteins in axons and dendrites. The phosphorylation of the alpha subunit of the translation initiation factor 2 (eIF2α) is one of the mechanisms of translational control. The phosphorylation of eIF2α has classically been viewed as a stress response, halting translation initiation. However, in the nervous system this type of regulation has been related to other mechanisms besides stress response, such as behavior, memory consolidation and nervous system development. Additionally, neurodegenerative diseases have a major stress component, thus eIF2α phosphorylation plays a preeminent role and its modulation is currently viewed as a new opportunity for therapeutic interventions. This review consolidates current information regarding eIF2α phosphorylation in neurons and its impact in neurodegenerative diseases. © 2016 Wiley Periodicals, Inc.
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Pasini S, Corona C, Liu J, Greene LA, Shelanski ML. Specific downregulation of hippocampal ATF4 reveals a necessary role in synaptic plasticity and memory. Cell Rep 2016; 11:183-91. [PMID: 25865882 DOI: 10.1016/j.celrep.2015.03.025] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 01/26/2015] [Accepted: 03/10/2015] [Indexed: 01/25/2023] Open
Abstract
Prior studies suggested that the transcription factor ATF4 negatively regulates synaptic plastic and memory. By contrast, we provide evidence from direct in vitro and in vivo knockdown of ATF4 in rodent hippocampal neurons and from ATF4-null mice that implicate ATF4 as essential for normal synaptic plasticity and memory. In particular, hippocampal ATF4 downregulation produces deficits in long-term spatial memory and behavioral flexibility without affecting associative memory or anxiety-like behavior. ATF4 knockdown or loss also causes profound impairment of both long-term potentiation (LTP) and long-term depression (LTD) as well as decreased glutamatergic function. We conclude that ATF4 is a key regulator of the physiological state necessary for neuronal plasticity and memory.
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18
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Ill-Raga G, Tajes M, Busquets-García A, Ramos-Fernández E, Vargas LM, Bosch-Morató M, Guivernau B, Valls-Comamala V, Eraso-Pichot A, Guix FX, Fandos C, Rosen MD, Rabinowitz MH, Maldonado R, Alvarez AR, Ozaita A, Muñoz FJ. Physiological Control of Nitric Oxide in Neuronal BACE1 Translation by Heme-Regulated eIF2α Kinase HRI Induces Synaptogenesis. Antioxid Redox Signal 2015; 22:1295-307. [PMID: 25706765 DOI: 10.1089/ars.2014.6080] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AIMS Hippocampus is the brain center for memory formation, a process that requires synaptogenesis. However, hippocampus is dramatically compromised in Alzheimer's disease due to the accumulation of amyloid β-peptide, whose production is initiated by β-site APP Cleaving Enzyme 1 (BACE1). It is known that pathological stressors activate BACE1 translation through the phosphorylation of the eukaryotic initiation factor-2α (eIF2α) by GCN2, PERK, or PKR kinases, leading to amyloidogenesis. However, BACE1 physiological regulation is still unclear. Since nitric oxide (NO) participates directly in hippocampal glutamatergic signaling, we investigated the neuronal role of the heme-regulated eukaryotic initiation factor eIF2α kinase (HRI), which can bind NO by a heme group, in BACE1 translation and its physiological consequences. RESULTS We found that BACE1 is expressed on glutamate activation with NO being the downstream effector by triggering eIF2α phosphorylation, as it was obtained by Western blot and luciferase assay. It is due to the activation of HRI by NO as assayed by Western blot and immunofluorescence with an HRI inhibitor and HRI siRNA. BACE1 expression was early detected at synaptic spines, contributing to spine growth and consolidating the hippocampal memory as assayed with mice treated with HRI or neuronal NO synthase inhibitors. INNOVATION We provide the first description that HRI and eIF2α are working in physiological conditions in the brain under the control of nitric oxide and glutamate signaling, and also that BACE1 has a physiological role in hippocampal function. CONCLUSION We conclude that BACE1 translation is controlled by NO through HRI in glutamatergic hippocampal synapses, where it plays physiological functions, allowing the spine growth and memory consolidation.
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Affiliation(s)
- Gerard Ill-Raga
- 1 Laboratory of Molecular Physiology and Channelopathies, Universitat Pompeu Fabra , Barcelona, Spain
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Lourenco MV, Ferreira ST, De Felice FG. Neuronal stress signaling and eIF2α phosphorylation as molecular links between Alzheimer's disease and diabetes. Prog Neurobiol 2015; 129:37-57. [PMID: 25857551 DOI: 10.1016/j.pneurobio.2015.03.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 03/10/2015] [Accepted: 03/29/2015] [Indexed: 12/22/2022]
Abstract
Mounting evidence from clinical, epidemiological, neuropathology and preclinical studies indicates that mechanisms similar to those leading to peripheral metabolic deregulation in metabolic disorders, such as diabetes and obesity, take place in the brains of Alzheimer's disease (AD) patients. These include pro-inflammatory mechanisms, brain metabolic stress and neuronal insulin resistance. From a molecular and cellular perspective, recent progress has been made in unveiling novel pathways that act in an orchestrated way to cause neuronal damage and cognitive decline in AD. These pathways converge to the activation of neuronal stress-related protein kinases and excessive phosphorylation of eukaryotic translation initiation factor 2α (eIF2α-P), which plays a key role in control of protein translation, culminating in synapse dysfunction and memory loss. eIF2α-P signaling thus links multiple neuronal stress pathways to impaired neuronal function and neurodegeneration. Here, we present a critical analysis of recently discovered molecular mechanisms underlying impaired brain insulin signaling and metabolic stress, with emphasis on the role of stress kinase/eIF2α-P signaling as a hub that promotes brain and behavioral impairments in AD. Because very similar mechanisms appear to operate in peripheral metabolic deregulation in T2D and in brain defects in AD, we discuss the concept that targeting defective brain insulin signaling and neuronal stress mechanisms with anti-diabetes agents may be an attractive approach to fight memory decline in AD. We conclude by raising core questions that remain to be addressed toward the development of much needed therapeutic approaches for AD.
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Affiliation(s)
- Mychael V Lourenco
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
| | - Sergio T Ferreira
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil; Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil
| | - Fernanda G De Felice
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
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Abstract
When exposed to environmental stresses, cells activate defence mechanisms to adapt stress and inhibit apoptotic pathways leading to their survival. Stressed cells also reduce their general metabolism in part by inhibiting mRNA translation, thereby saving energy needed to repair stress-induced damages. Under stress conditions, the inhibition of mRNA translation occurs mainly at its initiation step through the phosphorylation of the translation initiation factor eIF2α. One of the four kinases known to phosphorylate eIF2α is heme-regulated inhibitor (HRI). The activation of HRI occurs under conditions of heme deficiency, oxidative stress and treatment with anti-cancer drugs such as proteasome inhibitors. In this article, we discuss the role of HRI in promoting cell resistance to stress-mediated apoptosis.
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Affiliation(s)
- France-Hélène Joncas
- Département de biologie moléculaire, biochimie médicale et pathologie, faculté de médecine, université Laval, CHU de Québec St-François d'Assise, 10, rue de l'Espinay, G1L 3L5 Québec, Canada
| | - Pauline Adjibade
- Département de biologie moléculaire, biochimie médicale et pathologie, faculté de médecine, université Laval, CHU de Québec St-François d'Assise, 10, rue de l'Espinay, G1L 3L5 Québec, Canada
| | - Rachid Mazroui
- Département de biologie moléculaire, biochimie médicale et pathologie, faculté de médecine, université Laval, CHU de Québec St-François d'Assise, 10, rue de l'Espinay, G1L 3L5 Québec, Canada
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21
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Liu J, Pasini S, Shelanski ML, Greene LA. Activating transcription factor 4 (ATF4) modulates post-synaptic development and dendritic spine morphology. Front Cell Neurosci 2014; 8:177. [PMID: 25071442 PMCID: PMC4075335 DOI: 10.3389/fncel.2014.00177] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/07/2014] [Indexed: 11/15/2022] Open
Abstract
The ubiquitously expressed activating transcription factor 4 (ATF4) has been variably reported to either promote or inhibit neuronal plasticity and memory. However, the potential cellular bases for these and other actions of ATF4 in brain are not well-defined. In this report, we focus on ATF4's role in post-synaptic synapse development and dendritic spine morphology. shRNA-mediated silencing of ATF4 significantly reduces the densities of PSD-95 and GluR1 puncta (presumed markers of excitatory synapses) in long-term cultures of cortical and hippocampal neurons. ATF4 knockdown also decreases the density of mushroom spines and increases formation of abnormally-long dendritic filopodia in such cultures. In vivo knockdown of ATF4 in adult mouse hippocampal neurons also reduces mushroom spine density. In contrast, ATF4 over-expression does not affect the densities of PSD-95 puncta or mushrooom spines. Regulation of synaptic puncta and spine densities by ATF4 requires its transcriptional activity and is mediated at least in part by indirectly controlling the stability and expression of the total and active forms of the actin regulatory protein Cdc42. In support of such a mechanism, ATF4 silencing decreases the half-life of Cdc42 in cultured cortical neurons from 31.5 to 18.5 h while knockdown of Cdc42, like ATF4 knockdown, reduces the densities of mushroom spines and PSD-95 puncta. Thus, ATF4 appears to participate in neuronal development and plasticity by regulating the post-synaptic development of synapses and dendritic mushroom spines via a mechanism that includes regulation of Cdc42 levels.
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Affiliation(s)
- Jin Liu
- Department of Pathology and Cell Biology, Columbia University Medical Center New York, NY, USA
| | - Silvia Pasini
- Department of Pathology and Cell Biology, Columbia University Medical Center New York, NY, USA
| | - Michael L Shelanski
- Department of Pathology and Cell Biology, Columbia University Medical Center New York, NY, USA
| | - Lloyd A Greene
- Department of Pathology and Cell Biology, Columbia University Medical Center New York, NY, USA
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Drugs of abuse as memory modulators: a study of cocaine in rats. Psychopharmacology (Berl) 2014; 231:2339-48. [PMID: 24337026 DOI: 10.1007/s00213-013-3390-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 11/29/2013] [Indexed: 01/22/2023]
Abstract
RATIONALE It has been proposed that drugs of abuse reinforce behavior partly, or wholly, because they facilitate learning by enhancing memory consolidation. Cocaine can clearly serve as a reinforcer, but its effect on learning has not been fully characterized. OBJECTIVES To explore the effects of different regimens of pre- and post-training cocaine administration on win-stay and object learning. METHODS Cocaine naïve and cocaine pre-exposed (30 mg/kg/day, × 5 days followed by 7 days drug-free) male Sprague-Dawley rats received cocaine (0, 1, 2.5, 7.5, or 20 mg/kg, i.p.) immediately following training on a win-stay task in a radial maze or following the sample phase of an object learning task. Win-stay performance was also assessed in tests of extinction and after a set shift. RESULTS Post-training cocaine did not improve accuracy on the win-stay task and produced performance deficits at 20 mg/kg. These deficits were attenuated by prior cocaine exposure. There was indirect evidence of facilitated learning in extinction and set shift tests, but the effective dosage was different (2.5 and 7.5 mg/kg, respectively). Post-training cocaine produced dose-dependent improvements in object learning. CONCLUSION Post-training cocaine administration can facilitate learning, but this effect is highly dependent on the dose and the type of task employed.
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Uthayathas S, Parameshwaran K, Karuppagounder SS, Ahuja M, Dhanasekaran M, Suppiramaniam V. Selective inhibition of phosphodiesterase 5 enhances glutamatergic synaptic plasticity and memory in mice. Synapse 2013; 67:741-7. [PMID: 23620198 DOI: 10.1002/syn.21676] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Accepted: 04/11/2013] [Indexed: 01/06/2023]
Abstract
Phosphodiesterases (PDEs) belong to a family of proteins that control metabolism of cyclic nucleotides. Targeting PDE5, for enhancing cellular function, is one of the therapeutic strategies for male erectile dysfunction. We have investigated whether in vivo inhibition of PDE5, which is expressed in several brain regions, will enhance memory and synaptic transmission in the hippocampus of healthy mice. We have found that acute administration of sildenafil, a specific PDE5 inhibitor, enhanced hippocampus-dependent memory tasks. To elucidate the underlying mechanism in the memory enhancement, effects of sildenafil on long-term potentiation (LTP) were measured. The level of LTP was significantly elevated, with concomitant increases in basal synaptic transmission, in mice treated with sildenafil (1 mg/kg/day) for 15 days compared to control mice. These results suggest that moderate PDE5 inhibition enhances memory by increasing synaptic plasticity and transmission in the hippocampus.
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Affiliation(s)
- Subramaniam Uthayathas
- Department of Pharmacal Sciences, Harrison School of Pharmacy, Auburn University, Auburn, Alabama; Department of Pharmacology, Howard University College of Medicine, Washington, DC
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