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Wong LH, Tremethick DJ. Multifunctional histone variants in genome function. Nat Rev Genet 2024:10.1038/s41576-024-00759-1. [PMID: 39138293 DOI: 10.1038/s41576-024-00759-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2024] [Indexed: 08/15/2024]
Abstract
Histones are integral components of eukaryotic chromatin that have a pivotal role in the organization and function of the genome. The dynamic regulation of chromatin involves the incorporation of histone variants, which can dramatically alter its structural and functional properties. Contrary to an earlier view that limited individual histone variants to specific genomic functions, new insights have revealed that histone variants exert multifaceted roles involving all aspects of genome function, from governing patterns of gene expression at precise genomic loci to participating in genome replication, repair and maintenance. This conceptual change has led to a new understanding of the intricate interplay between chromatin and DNA-dependent processes and how this connection translates into normal and abnormal cellular functions.
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Affiliation(s)
- Lee H Wong
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - David J Tremethick
- The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capial Territory, Australia.
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2
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Navabpour S, Farrell K, Kincaid SE, Omar N, Musaus M, Lin Y, Xie H, Jarome TJ. Monoubiquitination of histone H2B is a crucial regulator of the transcriptome during memory formation. Learn Mem 2024; 31:a053912. [PMID: 38580378 PMCID: PMC11000578 DOI: 10.1101/lm.053912.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/07/2024] [Indexed: 04/07/2024]
Abstract
Posttranslational modification of histone proteins is critical for memory formation. Recently, we showed that monoubiquitination of histone H2B at lysine 120 (H2Bub) is critical for memory formation in the hippocampus. However, the transcriptome controlled by H2Bub remains unknown. Here, we found that fear conditioning in male rats increased or decreased the expression of 86 genes in the hippocampus but, surprisingly, siRNA-mediated knockdown of the H2Bub ligase, Rnf20, abolished changes in all but one of these genes. These findings suggest that monoubiquitination of histone H2B is a crucial regulator of the transcriptome during memory formation.
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Affiliation(s)
- Shaghayegh Navabpour
- Translational Biology, Medicine and Health Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Kayla Farrell
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Shannon E Kincaid
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Nour Omar
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Yu Lin
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia 24061, USA
| | - Hehuang Xie
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Blacksburg, Virginia 24061, USA
- Fralin Life Science Institute at Virginia Tech, Blacksburg, Virginia 24061, USA
| | - Timothy J Jarome
- Translational Biology, Medicine and Health Graduate Program, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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3
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Smalheiser NR. Mobile circular DNAs regulating memory and communication in CNS neurons. Front Mol Neurosci 2023; 16:1304667. [PMID: 38125007 PMCID: PMC10730651 DOI: 10.3389/fnmol.2023.1304667] [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: 09/29/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023] Open
Abstract
Stimuli that stimulate neurons elicit transcription of immediate-early genes, a process which requires local sites of chromosomal DNA to form double-strand breaks (DSBs) generated by topoisomerase IIb within a few minutes, followed by repair within a few hours. Wakefulness, exploring a novel environment, and contextual fear conditioning also elicit turn-on of synaptic genes requiring DSBs and repair. It has been reported (in non-neuronal cells) that extrachromosomal circular DNA can form at DSBs as the sites are repaired. I propose that activated neurons may generate extrachromosomal circular DNAs during repair at DSB sites, thus creating long-lasting "markers" of that activity pattern which contain sequences from their sites of origin and which regulate long-term gene expression. Although the population of extrachromosomal DNAs is diverse and overall associated with pathology, a subclass of small circular DNAs ("microDNAs," ∼100-400 bases long), largely derives from unique genomic sequences and has attractive features to act as stable, mobile circular DNAs to regulate gene expression in a sequence-specific manner. Circular DNAs can be templates for the transcription of RNAs, particularly small inhibitory siRNAs, circular RNAs and other non-coding RNAs that interact with microRNAs. These may regulate translation and transcription of other genes involved in synaptic plasticity, learning and memory. Another possible fate for mobile DNAs is to be inserted stably into chromosomes after new DSB sites are generated in response to subsequent activation events. Thus, the insertions of mobile DNAs into activity-induced genes may tend to inactivate them and aid in homeostatic regulation to avoid over-excitation, as well as providing a "counter" for a neuron's activation history. Moreover, activated neurons release secretory exosomes that can be transferred to recipient cells to regulate their gene expression. Mobile DNAs may be packaged into exosomes, released in an activity-dependent manner, and transferred to recipient cells, where they may be templates for regulatory RNAs and possibly incorporated into chromosomes. Finally, aging and neurodegenerative diseases (including Alzheimer's disease) are also associated with an increase in DSBs in neurons. It will become important in the future to assess how pathology-associated DSBs may relate to activity-induced mobile DNAs, and whether the latter may potentially contribute to pathogenesis.
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Affiliation(s)
- Neil R. Smalheiser
- Department of Psychiatry, University of Illinois College of Medicine, Chicago, IL, United States
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4
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Dyakonova VE. DNA Instability in Neurons: Lifespan Clock and Driver of Evolution. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1719-1731. [PMID: 38105193 DOI: 10.1134/s0006297923110044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 07/19/2023] [Accepted: 09/20/2023] [Indexed: 12/19/2023]
Abstract
In the last ten years, the discovery of neuronal DNA postmitotic instability has changed the theoretical landscape in neuroscience and, more broadly, biology. In 2003, A. M. Olovnikov suggested that neuronal DNA is the "initial substrate of aging". Recent experimental data have significantly increased the likelihood of this hypothesis. How does neuronal DNA accumulate damage and in what genome regions? What factors contribute to this process and how are they associated with aging and lifespan? These questions will be discussed in the review. In the course of Metazoan evolution, the instability of neuronal DNA has been accompanied by searching for the pathways to reduce the biological cost of brain activity. Various processes and activities, such as sleep, evolutionary increase in the number of neurons in the vertebrate brain, adult neurogenesis, distribution of neuronal activity, somatic polyploidy, and RNA editing in cephalopods, can be reconsidered in the light of the trade-off between neuronal plasticity and DNA instability in neurons. This topic is of considerable importance for both fundamental neuroscience and translational medicine.
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Affiliation(s)
- Varvara E Dyakonova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
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5
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Boutros SW, Zimmerman B, Nagy SC, Unni VK, Raber J. Age, sex, and apolipoprotein E isoform alter contextual fear learning, neuronal activation, and baseline DNA damage in the hippocampus. Mol Psychiatry 2023; 28:3343-3354. [PMID: 36732588 PMCID: PMC10618101 DOI: 10.1038/s41380-023-01966-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 01/06/2023] [Accepted: 01/16/2023] [Indexed: 02/04/2023]
Abstract
Age, female sex, and apolipoprotein E4 (E4) are risk factors to develop Alzheimer's disease (AD). There are three major human apoE isoforms: E2, E3, and E4. Compared to E3, E4 increases while E2 decreases AD risk. However, E2 is associated with increased risk and severity of post-traumatic stress disorder (PTSD). In cognitively healthy adults, E4 carriers have greater brain activation during learning and memory tasks in the absence of behavioral differences. Human apoE targeted replacement (TR) mice display differences in fear extinction that parallel human data: E2 mice show impaired extinction, mirroring heightened PTSD symptoms in E2 combat veterans. Recently, an adaptive role of DNA double strand breaks (DSBs) in immediate early gene expression (IEG) has been described. Age and disease synergistically increase DNA damage and decrease DNA repair. As the mechanisms underlying the relative risks of apoE, sex, and their interactions in aging are unclear, we used young (3 months) and middle-aged (12 months) male and female TR mice to investigate the influence of these factors on DSBs and IEGs at baseline and following contextual fear conditioning. We assessed brain-wide changes in neural activation following fear conditioning using whole-brain cFos imaging in young female TR mice. E4 mice froze more during fear conditioning and had lower cFos immunoreactivity across regions important for somatosensation and contextual encoding compared to E2 mice. E4 mice also showed altered co-activation compared to E3 mice, corresponding to human MRI and cognitive data, and indicating that there are differences in brain activity and connectivity at young ages independent of fear learning. There were increased DSB markers in middle-aged animals and alterations to cFos levels dependent on sex and isoform, as well. The increase in hippocampal DSB markers in middle-aged animals and female E4 mice may play a role in the risk for developing AD.
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Affiliation(s)
- Sydney Weber Boutros
- Department of Behavioral Neuroscience, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
- Department of Psychological Sciences, Boise State University, 2133 W Cesar Chavez Ln, Boise, ID, 83725, USA
| | - Benjamin Zimmerman
- Department of Behavioral Neuroscience, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
- Advanced Imaging Research Center, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
- Helfgott Research Institute, NUNM, 2201 SW First Avenue, Portland, OR, 97201, USA
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N, Matthews Avenue, Urbana, IL 61801, USA
| | - Sydney C Nagy
- Department of Behavioral Neuroscience, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
| | - Vivek K Unni
- Department of Neurology, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
- Jungers Center for Neurosciences Research, OHSU; and OHSU Parkinson Center, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
| | - Jacob Raber
- Department of Behavioral Neuroscience, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
- Department of Neurology, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
- Departments of Psychiatry and Radiation Medicine, OHSU, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
- Division of Neuroscience, ONPRC, 505 NW 185th Ave, Beaverton, OR, 97006, USA.
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6
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Delint-Ramirez I, Konada L, Heady L, Rueda R, Jacome ASV, Marlin E, Marchioni C, Segev A, Kritskiy O, Yamakawa S, Reiter AH, Tsai LH, Madabhushi R. Calcineurin dephosphorylates topoisomerase IIβ and regulates the formation of neuronal-activity-induced DNA breaks. Mol Cell 2022; 82:3794-3809.e8. [PMID: 36206766 PMCID: PMC9990814 DOI: 10.1016/j.molcel.2022.09.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 07/27/2022] [Accepted: 09/09/2022] [Indexed: 11/13/2022]
Abstract
Neuronal activity induces topoisomerase IIβ (Top2B) to generate DNA double-strand breaks (DSBs) within the promoters of neuronal early response genes (ERGs) and facilitate their transcription, and yet, the mechanisms that control Top2B-mediated DSB formation are unknown. Here, we report that stimulus-dependent calcium influx through NMDA receptors activates the phosphatase calcineurin to dephosphorylate Top2B at residues S1509 and S1511, which stimulates its DNA cleavage activity and induces it to form DSBs. Exposing mice to a fear conditioning paradigm also triggers Top2B dephosphorylation at S1509 and S1511 in the hippocampus, indicating that calcineurin also regulates Top2B-mediated DSB formation following physiological neuronal activity. Furthermore, calcineurin-Top2B interactions following neuronal activity and sites that incur activity-induced DSBs are preferentially localized at the nuclear periphery in neurons. Together, these results reveal how radial gene positioning and the compartmentalization of activity-dependent signaling govern the position and timing of activity-induced DSBs and regulate gene expression patterns in neurons.
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Affiliation(s)
- Ilse Delint-Ramirez
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Lahiri Konada
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Lance Heady
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Richard Rueda
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - Eric Marlin
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Charlotte Marchioni
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Amir Segev
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Oleg Kritskiy
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Satoko Yamakawa
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Ram Madabhushi
- Departments of Psychiatry, Neuroscience, and Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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7
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Farrell K, Auerbach A, Musaus M, Jarome TJ. The epigenetic role of proteasome subunit RPT6 during memory formation in female rats. Learn Mem 2022; 29:256-264. [PMID: 36206393 PMCID: PMC9488026 DOI: 10.1101/lm.053498.121] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 05/10/2022] [Indexed: 11/24/2022]
Abstract
Reports of sex differences in the neurobiology of memory formation are becoming more prevalent. Despite this, much remains unknown about the role of sex in this process. We previously reported the first evidence of a novel epigenetic role for proteasome subunit RPT6 during memory formation in the hippocampus of male rodents whereby it associated with monoubiquitinated histone H2B (H2Bubi). Here, we used molecular, biochemical, and behavioral approaches to investigate whether RPT6 has a similar epigenetic role during memory formation in female rats. Following contextual fear conditioning, we found that RPT6 levels and DNA binding at regions coding for c-fos, the previously identified target of RPT6 in males, were unchanged in the hippocampus of females and that loss of RPT6 did not alter learning-induced increases in c-fos However, RPT6 was in complex with H2Bubi in the female hippocampus and this association increased with fear conditioning, suggesting that it could still retain an epigenetic function. Consistent with this, hippocampal siRNA-mediated knockdown of the RPT6-coding gene, Psmc5, impaired memory in females. These results suggest that while RPT6 does associate with epigenetic H2Bubi during memory formation in both males and females, it has sex-specific gene targets during the memory consolidation process.
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Affiliation(s)
- Kayla Farrell
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Aubrey Auerbach
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Timothy J Jarome
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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8
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Weber Boutros S, Unni VK, Raber J. An Adaptive Role for DNA Double-Strand Breaks in Hippocampus-Dependent Learning and Memory. Int J Mol Sci 2022; 23:8352. [PMID: 35955487 PMCID: PMC9368779 DOI: 10.3390/ijms23158352] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 12/10/2022] Open
Abstract
DNA double-strand breaks (DSBs), classified as the most harmful type of DNA damage based on the complexity of repair, lead to apoptosis or tumorigenesis. In aging, DNA damage increases and DNA repair decreases. This is exacerbated in disease, as post-mortem tissue from patients diagnosed with mild cognitive impairment (MCI) or Alzheimer's disease (AD) show increased DSBs. A novel role for DSBs in immediate early gene (IEG) expression, learning, and memory has been suggested. Inducing neuronal activity leads to increases in DSBs and upregulation of IEGs, while increasing DSBs and inhibiting DSB repair impairs long-term memory and alters IEG expression. Consistent with this pattern, mice carrying dominant AD mutations have increased baseline DSBs, and impaired DSB repair is observed. These data suggest an adaptive role for DSBs in the central nervous system and dysregulation of DSBs and/or repair might drive age-related cognitive decline (ACD), MCI, and AD. In this review, we discuss the adaptive role of DSBs in hippocampus-dependent learning, memory, and IEG expression. We summarize IEGs, the history of DSBs, and DSBs in synaptic plasticity, aging, and AD. DSBs likely have adaptive functions in the brain, and even subtle alterations in their formation and repair could alter IEGs, learning, and memory.
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Affiliation(s)
- Sydney Weber Boutros
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA;
| | - Vivek K. Unni
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA;
- Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR 97239, USA
- Oregon Health & Science University Parkinson Center, Portland, OR 97239, USA
| | - Jacob Raber
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA;
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA;
- Department of Radiation Medicine, Oregon Health & Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA
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9
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Gustin A, Navabpour S, Farrell K, Martin K, DuVall J, Keith Ray W, Helm RF, Jarome TJ. Protein SUMOylation is a sex-specific regulator of fear memory formation in the amygdala. Behav Brain Res 2022; 430:113928. [PMID: 35597476 PMCID: PMC10431910 DOI: 10.1016/j.bbr.2022.113928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/11/2022] [Accepted: 05/12/2022] [Indexed: 11/25/2022]
Abstract
Strong evidence has implicated ubiquitin signaling in the process of fear memory formation. While less abundant than ubiquitination, evidence suggests that protein SUMOylation may also be involved in fear memory formation in neurons. However, the importance of amygdala protein SUMOylation in fear memory formation has never been directly examined. Furthermore, while recent evidence indicates that males and females differ significantly in the requirement for ubiquitin signaling during fear memory formation, whether sex differences also exist in the importance of protein SUMOylation to this process remains unknown. Here we found that males and females differ in the requirement for protein SUMOylation in the amygdala during fear memory formation. Western blot analysis revealed that while females had higher resting levels of SUMOylation, both sexes showed global increases following fear conditioning. However, SUMOylation-specific proteomic analysis revealed that only females have increased targeting of individual proteins by SUMOylation following fear conditioning, some of which were heat shock proteins. This suggests that protein SUMOylation is more robustly engaged in the amygdala of females following fear conditioning. In vivo siRNA mediated knockdown of Ube2i, the coding gene for the essential E2 ligase for SUMOylation conjugation, in the amygdala impaired fear memory in males without any effect in females. Importantly, higher siRNA concentrations than what was needed to impair memory in males reduced Ube2i levels in the amygdala of females but resulted in an increase in SUMOylation levels, suggesting a compensatory effect in females that was not observed in males. Collectively, these data reveal a novel, sex-specific role for protein SUMOylation in the amygdala during fear memory formation and expand our understanding of how ubiquitin-like signaling regulates memory formation.
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Affiliation(s)
- Aspen Gustin
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Shaghayegh Navabpour
- Fralin Biomedical Research Institute, Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA
| | - Kayla Farrell
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Jessica DuVall
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - W Keith Ray
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Richard F Helm
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Timothy J Jarome
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA; Fralin Biomedical Research Institute, Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, USA; School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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10
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The Role of Transposable Elements of the Human Genome in Neuronal Function and Pathology. Int J Mol Sci 2022; 23:ijms23105847. [PMID: 35628657 PMCID: PMC9148063 DOI: 10.3390/ijms23105847] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/17/2022] [Accepted: 05/19/2022] [Indexed: 12/13/2022] Open
Abstract
Transposable elements (TEs) have been extensively studied for decades. In recent years, the introduction of whole-genome and whole-transcriptome approaches, as well as single-cell resolution techniques, provided a breakthrough that uncovered TE involvement in host gene expression regulation underlying multiple normal and pathological processes. Of particular interest is increased TE activity in neuronal tissue, and specifically in the hippocampus, that was repeatedly demonstrated in multiple experiments. On the other hand, numerous neuropathologies are associated with TE dysregulation. Here, we provide a comprehensive review of literature about the role of TEs in neurons published over the last three decades. The first chapter of the present review describes known mechanisms of TE interaction with host genomes in general, with the focus on mammalian and human TEs; the second chapter provides examples of TE exaptation in normal neuronal tissue, including TE involvement in neuronal differentiation and plasticity; and the last chapter lists TE-related neuropathologies. We sought to provide specific molecular mechanisms of TE involvement in neuron-specific processes whenever possible; however, in many cases, only phenomenological reports were available. This underscores the importance of further studies in this area.
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11
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Pommier Y, Nussenzweig A, Takeda S, Austin C. Human topoisomerases and their roles in genome stability and organization. Nat Rev Mol Cell Biol 2022; 23:407-427. [PMID: 35228717 PMCID: PMC8883456 DOI: 10.1038/s41580-022-00452-3] [Citation(s) in RCA: 121] [Impact Index Per Article: 60.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
Human topoisomerases comprise a family of six enzymes: two type IB (TOP1 and mitochondrial TOP1 (TOP1MT), two type IIA (TOP2A and TOP2B) and two type IA (TOP3A and TOP3B) topoisomerases. In this Review, we discuss their biochemistry and their roles in transcription, DNA replication and chromatin remodelling, and highlight the recent progress made in understanding TOP3A and TOP3B. Because of recent advances in elucidating the high-order organization of the genome through chromatin loops and topologically associating domains (TADs), we integrate the functions of topoisomerases with genome organization. We also discuss the physiological and pathological formation of irreversible topoisomerase cleavage complexes (TOPccs) as they generate topoisomerase DNA–protein crosslinks (TOP-DPCs) coupled with DNA breaks. We discuss the expanding number of redundant pathways that repair TOP-DPCs, and the defects in those pathways, which are increasingly recognized as source of genomic damage leading to neurological diseases and cancer. Topoisomerases have essential roles in transcription, DNA replication, chromatin remodelling and, as recently revealed, 3D genome organization. However, topoisomerases also generate DNA–protein crosslinks coupled with DNA breaks, which are increasingly recognized as a source of disease-causing genomic damage.
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12
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Epigenetic Mechanisms in Memory and Cognitive Decline Associated with Aging and Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms222212280. [PMID: 34830163 PMCID: PMC8618067 DOI: 10.3390/ijms222212280] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 12/21/2022] Open
Abstract
Epigenetic mechanisms, which include DNA methylation, a variety of post-translational modifications of histone proteins (acetylation, phosphorylation, methylation, ubiquitination, sumoylation, serotonylation, dopaminylation), chromatin remodeling enzymes, and long non-coding RNAs, are robust regulators of activity-dependent changes in gene transcription. In the brain, many of these epigenetic modifications have been widely implicated in synaptic plasticity and memory formation. Dysregulation of epigenetic mechanisms has been reported in the aged brain and is associated with or contributes to memory decline across the lifespan. Furthermore, alterations in the epigenome have been reported in neurodegenerative disorders, including Alzheimer’s disease. Here, we review the diverse types of epigenetic modifications and their role in activity- and learning-dependent synaptic plasticity. We then discuss how these mechanisms become dysregulated across the lifespan and contribute to memory loss with age and in Alzheimer’s disease. Collectively, the evidence reviewed here strongly supports a role for diverse epigenetic mechanisms in memory formation, aging, and neurodegeneration in the brain.
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Farrell K, Musaus M, Navabpour S, Martin K, Ray WK, Helm RF, Jarome TJ. Proteomic Analysis Reveals Sex-Specific Protein Degradation Targets in the Amygdala During Fear Memory Formation. Front Mol Neurosci 2021; 14:716284. [PMID: 34658783 PMCID: PMC8511838 DOI: 10.3389/fnmol.2021.716284] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/01/2021] [Indexed: 11/25/2022] Open
Abstract
Ubiquitin-proteasome mediated protein degradation has been widely implicated in fear memory formation in the amygdala. However, to date, the protein targets of the proteasome remain largely unknown, limiting our understanding of the functional significance for protein degradation in fear memory formation. Additionally, whether similar proteins are targeted by the proteasome between sexes has yet to be explored. Here, we combined a degradation-specific K48 Tandem Ubiquitin Binding Entity (TUBE) with liquid chromatography mass spectrometry (LC/MS) to identify the target substrates of the protein degradation process in the amygdala of male and female rats following contextual fear conditioning. We found that males (43) and females (77) differed in the total number of proteins that had significant changes in K48 polyubiquitin targeting in the amygdala following fear conditioning. Many of the identified proteins (106) had significantly reduced levels in the K48-purified samples 1 h after fear conditioning, suggesting active degradation of the substrate due to learning. Interestingly, only 3 proteins overlapped between sexes, suggesting that targets of the protein degradation process may be sex-specific. In females, many proteins with altered abundance in the K48-purified samples were involved in vesicle transport or are associated with microtubules. Conversely, in males, proteins involved in the cytoskeleton, ATP synthesis and cell signaling were found to have significantly altered abundance. Only 1 protein had an opposite directional change in abundance between sexes, LENG1, which was significantly enhanced in males while lower in females. This suggests a more rapid degradation of this protein in females during fear memory formation. Interestingly, GFAP, a critical component of astrocyte structure, was a target of K48 polyubiquitination in both males and females, indicating that protein degradation is likely occurring in astrocytes following fear conditioning. Western blot assays revealed reduced levels of these target substrates following fear conditioning in both sexes, confirming that the K48 polyubiquitin was targeting these proteins for degradation. Collectively, this study provides strong evidence that sex differences exist in the protein targets of the degradation process in the amygdala following fear conditioning and critical information regarding how ubiquitin-proteasome mediated protein degradation may contribute to fear memory formation in the brain.
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Affiliation(s)
- Kayla Farrell
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Madeline Musaus
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Shaghayegh Navabpour
- Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, United States
| | - Kiley Martin
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - W Keith Ray
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Richard F Helm
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Timothy J Jarome
- Department of Animal and Poultry Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.,School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States.,Department of Translational Biology, Medicine and Health, Virginia Polytechnic Institute and State University, Roanoke, VA, United States
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14
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Dileep V, Tsai LH. Three-dimensional chromatin organization in brain function and dysfunction. Curr Opin Neurobiol 2021; 69:214-221. [PMID: 34111830 DOI: 10.1016/j.conb.2021.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/20/2021] [Accepted: 04/29/2021] [Indexed: 01/24/2023]
Abstract
The three-dimensional (3D) organization of chromatin within the nucleus is now recognized as a bona fide epigenetic property influencing genome function, replication, and maintenance. In the recent years, several studies have revealed how 3D chromatin organization is associated with brain function and its emerging role in disorders of the brain. 3D chromatin organization plays a crucial role in the development of different cell types of the nervous system and some neuronal cell types have adapted unique modifications to this organization that deviates from all other cell types. In post-mitotic neurons, dynamic changes in chromatin interactions in response to neuronal activity underlie learning and memory formation. Finally, new evidence directly links 3D chromatin organization to several disorders of the brain. These recent findings position 3D chromatin organization as a fundamental regulatory mechanism poised to reveal the etiology of brain function and dysfunctions.
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Affiliation(s)
- Vishnu Dileep
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Broad Institute of Harvard and MIT, Cambridge, MA, USA.
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15
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Stott RT, Kritsky O, Tsai LH. Profiling DNA break sites and transcriptional changes in response to contextual fear learning. PLoS One 2021; 16:e0249691. [PMID: 34197463 PMCID: PMC8248687 DOI: 10.1371/journal.pone.0249691] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/27/2021] [Indexed: 12/12/2022] Open
Abstract
Neuronal activity generates DNA double-strand breaks (DSBs) at specific loci in vitro and this facilitates the rapid transcriptional induction of early response genes (ERGs). Physiological neuronal activity, including exposure of mice to learning behaviors, also cause the formation of DSBs, yet the distribution of these breaks and their relation to brain function remains unclear. Here, following contextual fear conditioning (CFC) in mice, we profiled the locations of DSBs genome-wide in the medial prefrontal cortex and hippocampus using γH2AX ChIP-Seq. Remarkably, we found that DSB formation is widespread in the brain compared to cultured primary neurons and they are predominately involved in synaptic processes. We observed increased DNA breaks at genes induced by CFC in neuronal and non-neuronal nuclei. Activity-regulated and proteostasis-related transcription factors appear to govern some of these gene expression changes across cell types. Finally, we find that glia but not neurons have a robust transcriptional response to glucocorticoids, and many of these genes are sites of DSBs. Our results indicate that learning behaviors cause widespread DSB formation in the brain that are associated with experience-driven transcriptional changes across both neuronal and glial cells.
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Affiliation(s)
- Ryan T. Stott
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Oleg Kritsky
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States of America
| | - Li-Huei Tsai
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, United States of America
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States of America
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16
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Jarome TJ, Kwapis JL. Special Issue "Molecular Mechanisms of Memory Formation and Modification". Int J Mol Sci 2021; 22:ijms22084113. [PMID: 33923416 PMCID: PMC8072671 DOI: 10.3390/ijms22084113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 04/13/2021] [Indexed: 11/16/2022] Open
Abstract
Memory is vital to human functioning and controls future behavioral responses [...].
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Affiliation(s)
- Timothy J. Jarome
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
- Correspondence: (T.J.J.); (J.L.K.); Tel.: +1-540-231-3520 (T.J.J.); +1-814-863-0859 (J.L.K.)
| | - Janine L. Kwapis
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
- Center for the Molecular Investigation of Neurological Disorders (CMIND), Pennsylvania State University, University Park, PA 16802, USA
- Correspondence: (T.J.J.); (J.L.K.); Tel.: +1-540-231-3520 (T.J.J.); +1-814-863-0859 (J.L.K.)
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