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Ouyang X, Wani WY, Benavides GA, Redmann MJ, Vo H, van Groen T, Darley-Usmar VM, Zhang J. Cathepsin D overexpression in the nervous system rescues lethality and A β42 accumulation of cathepsin D systemic knockout in vivo. Acta Pharm Sin B 2023; 13:4172-4184. [PMID: 37799377 PMCID: PMC10547960 DOI: 10.1016/j.apsb.2023.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/26/2023] [Accepted: 06/13/2023] [Indexed: 10/07/2023] Open
Abstract
The lysosome is responsible for protein and organelle degradation and homeostasis and the cathepsins play a key role in maintaining protein quality control. Cathepsin D (CTSD), is one such lysosomal protease, which when deficient in humans lead to neurolipofuscinosis (NCL) and is important in removing toxic protein aggregates. Prior studies demonstrated that CTSD germ-line knockout-CtsdKO (CDKO) resulted in accumulation of protein aggregates, decreased proteasomal activities, and postnatal lethality on Day 26 ± 1. Overexpression of wildtype CTSD, but not cathepsin B, L or mutant CTSD, decreased α-synuclein toxicity in worms and mammalian cells. In this study we generated a mouse line expressing human CTSD with a floxed STOP cassette between the ubiquitous CAG promoter and the cDNA. After crossing with Nestin-cre, the STOP cassette is deleted in NESTIN + cells to allow CTSD overexpression-CTSDtg (CDtg). The CDtg mice exhibited normal behavior and similar sensitivity to sub-chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced neurodegeneration. By breeding CDtg mice with CDKO mice, we found that over-expression of CTSD extended the lifespan of the CDKO mice, partially rescued proteasomal deficits and the accumulation of Aβ42 in the CDKO. This new transgenic mouse provides supports for the key role of CTSD in protecting against proteotoxicity and offers a new model to study the role of CTSD enhancement in vivo.
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Affiliation(s)
- Xiaosen Ouyang
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Willayat Y. Wani
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Gloria A. Benavides
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Matthew J. Redmann
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Hai Vo
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Thomas van Groen
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | | | - Jianhua Zhang
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Birmingham VA Medical Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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2
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Noyes NC, Phan A, Davis RL. Memory suppressor genes: Modulating acquisition, consolidation, and forgetting. Neuron 2021; 109:3211-3227. [PMID: 34450024 PMCID: PMC8542634 DOI: 10.1016/j.neuron.2021.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/15/2021] [Accepted: 07/30/2021] [Indexed: 02/06/2023]
Abstract
The brain has a remarkable but underappreciated capacity to limit memory formation and expression. The term "memory suppressor gene" was coined in 1998 as an attempt to explain emerging reports that some genes appeared to limit memory. At that time, only a handful of memory suppressor genes were known, and they were understood to work by limiting cAMP-dependent consolidation. In the intervening decades, almost 100 memory suppressor genes with diverse functions have been discovered that affect not only consolidation but also acquisition and forgetting. Here we highlight the surprising extent to which biological limits are placed on memory formation through reviewing the literature on memory suppressor genes. In this review, we present memory suppressors within the framework of their actions on different memory operations: acquisition, consolidation, and forgetting. This is followed by a discussion of the reasons why there may be a biological need to limit memory formation.
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Affiliation(s)
- Nathaniel C Noyes
- Department of Neuroscience, Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Anna Phan
- Department of Biological Sciences, University of Alberta, 11355 Saskatchewan Drive, Edmonton, AB T6G 2E9, Canada
| | - Ronald L Davis
- Department of Neuroscience, Scripps Research Institute Florida, Jupiter, FL 33458, USA.
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3
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Kulbay M, Bernier-Parker N, Bernier J. The role of the DFF40/CAD endonuclease in genomic stability. Apoptosis 2021; 26:9-23. [PMID: 33387146 DOI: 10.1007/s10495-020-01649-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2020] [Indexed: 12/18/2022]
Abstract
Maintenance of genomic stability in cells is primordial for cellular integrity and protection against tumor progression. Many factors such as ultraviolet light, oxidative stress, exposure to chemical reagents, particularly mutagens and radiation, can alter the integrity of the genome. Thus, human cells are equipped with many mechanisms that prevent these irreversible lesions in the genome, as DNA repair pathways, cell cycle checkpoints, and telomeric function. These mechanisms activate cellular apoptosis to maintain DNA stability. Emerging studies have proposed a new protein in the maintenance of genomic stability: the DNA fragmentation factor (DFF). The DFF40 is an endonuclease responsible of the oligonucleosomal fragmentation of the DNA during apoptosis. The lack of DFF in renal carcinoma cells induces apoptosis without oligonucleosomal fragmentation, which poses a threat to genetic information transfer between cancerous and healthy cells. In this review, we expose the link between the DFF and genomic instability as the source of disease development.
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Affiliation(s)
- Merve Kulbay
- INRS - Centre Armand-Frappier-Santé-Biotechnologie, 531 Boul. des Prairies, Laval, QC, H7V 1B7, Canada.,Department of Medicine, Université de Montréal, 2900 Blvd. Edouard Montpetit, Montreal, QC, Canada
| | - Nathan Bernier-Parker
- Toronto Animal Health Partners Emergency and Specialty Hospital, 1 Scarsdale Road, North York, ON, M3B 2R2, Canada
| | - Jacques Bernier
- INRS - Centre Armand-Frappier-Santé-Biotechnologie, 531 Boul. des Prairies, Laval, QC, H7V 1B7, Canada.
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4
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Nuclear receptor binding factor 2 (NRBF2) is required for learning and memory. J Transl Med 2020; 100:1238-1251. [PMID: 32350405 DOI: 10.1038/s41374-020-0433-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 01/13/2023] Open
Abstract
The mechanisms which underlie defects in learning and memory are a major area of focus with the increasing incidence of Alzheimer's disease in the aging population. The complex genetically-controlled, age-, and environmentally-dependent onset and progression of the cognitive deficits and neuronal pathology call for better understanding of the fundamental biology of the nervous system function. In this study, we focus on nuclear receptor binding factor-2 (NRBF2) which modulates the transcriptional activities of retinoic acid receptor α and retinoid X receptor α, and the autophagic activities of the BECN1-VPS34 complex. Since both transcriptional regulation and autophagic function are important in supporting neuronal function, we hypothesized that NRBF2 deficiency may lead to cognitive deficits. To test this, we developed a new mouse model with nervous system-specific knockout of Nrbf2. In a series of behavioral assessment, we demonstrate that NRBF2 knockout in the nervous system results in profound learning and memory deficits. Interestingly, we did not find deficits in autophagic flux in primary neurons and the autophagy deficits were minimal in the brain. In contrast, RNAseq analyses have identified altered expression of genes that have been shown to impact neuronal function. The observation that NRBF2 is involved in learning and memory suggests a new mechanism regulating cognition involving the role of this protein in regulating networks related to the function of retinoic acid receptors, protein folding, and quality control.
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5
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Lee YS. Genes and signaling pathways involved in memory enhancement in mutant mice. Mol Brain 2014; 7:43. [PMID: 24894914 PMCID: PMC4050447 DOI: 10.1186/1756-6606-7-43] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 05/27/2014] [Indexed: 11/10/2022] Open
Abstract
Mutant mice have been used successfully as a tool for investigating the mechanisms of memory at multiple levels, from genes to behavior. In most cases, manipulating a gene expressed in the brain impairs cognitive functions such as memory and their underlying cellular mechanisms, including synaptic plasticity. However, a remarkable number of mutations have been shown to enhance memory in mice. Understanding how to improve a system provides valuable insights into how the system works under normal conditions, because this involves understanding what the crucial components are. Therefore, more can be learned about the basic mechanisms of memory by studying mutant mice with enhanced memory. This review will summarize the genes and signaling pathways that are altered in the mutants with enhanced memory, as well as their roles in synaptic plasticity. Finally, I will discuss how knowledge of memory-enhancing mechanisms could be used to develop treatments for cognitive disorders associated with impaired plasticity.
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Affiliation(s)
- Yong-Seok Lee
- Department of Life Science, College of Natural Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
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6
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Molecular mechanism of size control in development and human diseases. Cell Res 2011; 21:715-29. [PMID: 21483452 DOI: 10.1038/cr.2011.63] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
How multicellular organisms control their size is a fundamental question that fascinated generations of biologists. In the past 10 years, tremendous progress has been made toward our understanding of the molecular mechanism underlying size control. Original studies from Drosophila showed that in addition to extrinsic nutritional and hormonal cues, intrinsic mechanisms also play important roles in the control of organ size during development. Several novel signaling pathways such as insulin and Hippo-LATS signaling pathways have been identified that control organ size by regulating cell size and/or cell number through modulation of cell growth, cell division, and cell death. Later studies using mammalian cell and mouse models also demonstrated that the signaling pathways identified in flies are also conserved in mammals. Significantly, recent studies showed that dysregulation of size control plays important roles in the development of many human diseases such as cancer, diabetes, and hypertrophy.
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Abstract
Most molecular and cellular studies of cognitive function have focused on either normal or pathological states, but recent research with transgenic mice has started to address the mechanisms of enhanced cognition. These results point to key synaptic and nuclear signalling events that can be manipulated to facilitate the induction or increase the stability of synaptic plasticity, and therefore enhance the acquisition or retention of information. Here, we review these surprising findings and explore their implications to both mechanisms of learning and memory and to ongoing efforts to develop treatments for cognitive disorders. These findings represent the beginning of a fundamental new approach in the study of enhanced cognition.
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Affiliation(s)
- Yong-Seok Lee
- Department of Neurobiology, Brain Research Institute, University of California, Los Angeles, California 90095, USA
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8
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Dong M, Fan Y, Toepfer NJ, Zhang J. Deficiency of DNA fragmentation factor 45 results in reduced oocyte apoptosis in response to doxorubicin. Cell Res 2007; 17:735-6. [PMID: 17667916 DOI: 10.1038/cr.2007.62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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9
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Gemma C, Bickford PC. Interleukin-1beta and caspase-1: players in the regulation of age-related cognitive dysfunction. Rev Neurosci 2007; 18:137-48. [PMID: 17593876 DOI: 10.1515/revneuro.2007.18.2.137] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Scientific research on the unprecedented and growing number of older adults in the United States and other industrialized countries has focused much attention on the health consequences of aging. Over the last few decades, inflammation in the brain and its implication in the progression of aging and age-related cognitive dysfunction has been an area of increasing importance to neuroscientists and is now considered as one of the most interesting and promising topics for aging research. One of the critical aspects of inflammatory processes is that the activation of one upstream inflammatory molecule initiates a cascade of self-sustaining inflammatory events which leads to the activation of a number of different downstream functions. Recently, a great deal of attention has been given to the interplay between inflammatory and apoptotic processes and the regulation of these processes by the caspases. The caspase family of proteases can be divided into proapoptotic and pro-inflammatory members. The present review summarizes recent observations of the interactions between the inflammatory cytokine interleuldn-1 (IL-1) beta and the inflammatory/apoptotic caspase-1 and their involvement in age-related impairments in cognition. A comprehensive understanding of these mechanisms could potentially lead to the development of preventive or protective therapies that reduce or inhibit the cognitive decline associated with aging and age-related neurodegenerative disease.
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Affiliation(s)
- Carmelina Gemma
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery, University of South Florida College of Medicine, Tampa, FL 33612, USA
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10
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Yan B, Wang H, Li F, Li CY. Regulation of mammalian horizontal gene transfer by apoptotic DNA fragmentation. Br J Cancer 2006; 95:1696-700. [PMID: 17146478 PMCID: PMC2360754 DOI: 10.1038/sj.bjc.6603484] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Previously it was shown that horizontal DNA transfer between mammalian cells can occur through the uptake of apoptotic bodies, where genes from the apoptotic cells were transferred to neighbouring cells phagocytosing the apoptotic bodies. The regulation of this process is poorly understood. It was shown that the ability of cells as recipient of horizontally transferred DNA was enhanced by deficiency of p53 or p21. However, little is known with regard to the regulation of DNA from donor apoptotic cells. Here we report that the DNA fragmentation factor/caspase-activated DNase (DFF/CAD), which is the endonuclease responsible for DNA fragmentation during apoptosis, plays a significant role in regulation of horizontal DNA transfer. Cells with inhibited DFF/CAD function are poor donors for horizontal gene transfer (HGT) while their ability of being recipients of HGT is not affected.
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Affiliation(s)
- B Yan
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
| | - H Wang
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - F Li
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Radiation Oncology, University of Colorado Health Sciences Center, Aurora, CO 80045, USA
| | - C-Y Li
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
- Department of Radiation Oncology, University of Colorado Health Sciences Center, Aurora, CO 80045, USA
- E-mail:
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11
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Yan B, Wang H, Wang H, Zhuo D, Li F, Kon T, Dewhirst M, Li CY. Apoptotic DNA fragmentation factor maintains chromosome stability in a P53-independent manner. Oncogene 2006; 25:5370-6. [PMID: 16619042 DOI: 10.1038/sj.onc.1209535] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA fragmentation factor (DFF)/caspase-activated DNase (CAD) is responsible for DNA fragmentation, a hallmark event during apoptosis. Although DNA fragmentation is an evolutionarily conserved process across species, its biological function is not clearly understood. In this study, we constructed cell lines expressing a mutant ICAD (inhibitor of CAD) protein that is resistant to caspase cleavage and therefore constantly binds to DFF/CAD and inhibits DNA fragmentation. We found that irradiation of these cells led to increased chromosome aberrations and aneuploidy when compared with their parental controls. The increased chromosome instability is observed irrespective of cellular P53 status, suggesting that the effect of DFF/CAD is independent of P53. Inhibition of apoptotic DNA fragmentation resulted in increased clonogenic survival of irradiated cells and a delay in removal of cells with DNA damages induced by radiation, an effect similar to that in cells with p53 mutations. Consistent with DFF/CAD's effect on clonogenic survival, tumors established from cells deficient in DNA fragmentation showed enhanced growth in nude mice. Therefore, our results suggest that DFF/CAD plays an important and P53-independent role in maintaining chromosome stability and suppressing tumor development.
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Affiliation(s)
- B Yan
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
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12
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Gemma C, Fister M, Hudson C, Bickford PC. Improvement of memory for context by inhibition of caspase-1 in aged rats. Eur J Neurosci 2006; 22:1751-6. [PMID: 16197515 DOI: 10.1111/j.1460-9568.2005.04334.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Impaired learning and memory is a common pathologic feature associated with numerous neurologic disorders. There is strong evidence that central inflammation contributes significantly to the progression of several neurodegenerative diseases as well as to the ageing process. For example, in aged rats an increase in interleukin-1beta (IL-1beta) is implicated in the decline of synaptic plasticity in the hippocampus and impaired performance on cognitive tasks such as contextual fear conditioning. IL-1beta is a proinflammatory cytokine initially synthesized in an inactive precursor form that is cleaved by caspase-1 to generate the biologically mature form. In the present study, cleavage of IL-1beta was chronically inhibited using a specific caspase-1 inhibitor (Ac-YVAD-CMK; 10 pmol) in both aged (22 month) and young (4 month) rats. Both groups received Ac-YVAD-CMK for 28 days intracerebroventricularly through a brain infusion cannula connected to an osmotic minipump. On day 20 the animals were trained in contextual fear conditioning, and memory for context was tested on day 22. Chronic infusion of a specific caspase-1 inhibitor in aged rats ameliorated age-related increases in hippocampal IL-1beta and improved memory for context.
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Affiliation(s)
- Carmelina Gemma
- James A. Haley VA Hospital, 13000 Bruce B. Downs Blvd., Tampa, FL, 33612, USA
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13
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Parrish JZ, Xue D. Cuts can kill: the roles of apoptotic nucleases in cell death and animal development. Chromosoma 2006; 115:89-97. [PMID: 16418867 DOI: 10.1007/s00412-005-0038-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 11/28/2005] [Accepted: 11/28/2005] [Indexed: 12/28/2022]
Abstract
Chromosome fragmentation is one of the major biochemical hallmarks of apoptosis. However, until recently, its roles in apoptosis and mechanisms of action remained elusive. Recent biochemical and genetic studies have shown that chromosome fragmentation is a complex biochemical process that involves a plethora of conserved nucleases with distinct nuclease activities and substrate specificities. These apoptotic nucleases act cooperatively among themselves and with other nonnuclease cofactors to promote stepwise chromosome fragmentation and DNA degradation. Importantly, in addition to its direct contribution to the dismantling of the dying cell, apoptotic DNA degradation can facilitate cell killing and other apoptotic events such as clearance of apoptotic cells. Furthermore, some apoptotic nucleases apparently affect other aspects of animal development, including immune responses. The identification of new apoptotic nucleases and analysis of their functions in apoptosis and animal development should pave the way for future studies to uncover new functions for apoptotic nucleases and shed light on the hidden links between apoptotic DNA degradation and human diseases.
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Affiliation(s)
- Jay Z Parrish
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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14
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Samejima K, Earnshaw WC. Trashing the genome: the role of nucleases during apoptosis. Nat Rev Mol Cell Biol 2005; 6:677-88. [PMID: 16103871 DOI: 10.1038/nrm1715] [Citation(s) in RCA: 221] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Two classes of nucleases degrade the cellular DNA during apoptosis. Cell-autonomous nucleases cleave DNA within the dying cell. They are not essential for apoptotic cell death or the life of the organism, but they might affect the efficiency of the process. By contrast, waste-management nucleases are essential for the life of the organism. In post-engulfment DNA degradation, the DNA of apoptotic cells is destroyed in lysosomes of the cells that have phagocytosed the corpses. Waste-management nucleases also destroy DNA that is released into the extracellular compartment. Here, we describe the complex group of nucleases that are involved in DNA destruction during apoptotic cell death.
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Affiliation(s)
- Kumiko Samejima
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, University of Edinburgh, Swann Building, King's Buildings, Mayfield Road, Edinburgh EH9 3JR, UK
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15
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Abstract
Most mammalian cells have nuclei that contain DNA, which replicates during cell proliferation. DNA is destroyed by various developmental processes in mammals. It is degraded during programmed cell death that accompanies mammalian development. The nuclei of erythrocytes and eye lens fiber cells are also removed during their differentiation into mature cells. If DNA is not properly degraded in these processes, it can cause various diseases, including tissue atrophy, anemia, cataract, and autoimmune diseases, which indicates that DNA can be a pathogenic molecule. Here, I present how DNA is degraded during programmed cell death, erythroid cell differentiation, and lens cell differentiation. I discuss what might be or will be learned from understanding the molecular mechanisms of DNA degradation that occurs during mammalian development.
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Affiliation(s)
- Shigekazu Nagata
- Laboratory of Genetics, Integrated Biology Laboratories, Graduate School of Frontier Biosciences, Osaka University, Japan.
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16
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Zhang J, Dong M, Li L, Fan Y, Pathre P, Dong J, Lou D, Wells JM, Olivares-Villagómez D, Van Kaer L, Wang X, Xu M. Endonuclease G is required for early embryogenesis and normal apoptosis in mice. Proc Natl Acad Sci U S A 2003; 100:15782-7. [PMID: 14663139 PMCID: PMC307645 DOI: 10.1073/pnas.2636393100] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Endonuclease G (EndoG) is a nuclear-encoded mitochondrial protein reported to be important for both nuclear DNA fragmentation during apoptosis and mitochondrial DNA replication. To evaluate the in vivo function of EndoG, we have investigated the effects of EndoG deficiency in cells and mice. We found that EndoG homozygous mutant embryos die between embryonic days 2.5 and 3.5. Mitochondrial DNA copy numbers in ovulated oocytes from EndoG heterozygous mutant and wild-type mice are similar, suggesting that EndoG is involved in a cellular function unrelated to mitochondrial DNA replication. Interestingly, we found that cells from EndoG heterozygous mutant mice exhibit increased resistance to both tumor necrosis factor alpha- and staurosporine-induced cell death. Moreover, spontaneous cell death of spermatogonia in EndoG heterozygous mutant mice is significantly reduced compared with wild-type mice. DNA fragmentation is also reduced in EndoG+/- thymocytes and splenocytes compared with wild-type cells, as well as in EndoG+/- thymus in vivo compared with that of the wild-type mice, on activation of apoptosis. These findings indicate that EndoG is essential during early embryogenesis and plays a critical role in normal apoptosis and nuclear DNA fragmentation.
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Affiliation(s)
- Jianhua Zhang
- Department of Cell Biology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
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Widlak P, Lanuszewska J, Cary RB, Garrard WT. Subunit structures and stoichiometries of human DNA fragmentation factor proteins before and after induction of apoptosis. J Biol Chem 2003; 278:26915-22. [PMID: 12748178 DOI: 10.1074/jbc.m303807200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA fragmentation factor (DFF) is one of the major endonucleases responsible for internucleosomal DNA cleavage during apoptosis. Understanding the regulatory checkpoints involved in safeguarding non-apoptotic cells against accidental activation of this nuclease is as important as elucidating its activation mechanisms during apoptosis. Here we address these issues by determining DFF native subunit structures and stoichiometries in human cells before and after induction of apoptosis using the technique of native pore-exclusion limit electrophoresis in combination with Western analyses. For comparison, we employed similar techniques with recombinant proteins in conjunction with atomic force microscopy. Before induction of apoptosis, the expression of DFF subunits varied widely among the cell types studied, and the chaperone/inhibitor subunits DFF45 and DFF35 unexpectedly existed primarily as monomers in vast excess of the latent nuclease subunit, DFF40, which was stoichiometrically associated with DFF45 to form heterodimers. DFF35 was exclusively cytoplasmic as a monomer. Nuclease activation upon caspase-3 cleavage of DFF45/DFF35 was accompanied by DFF40 homo-oligomer formation, with a tetramer being the smallest unit. Interestingly, intact DFF45 can inhibit nuclease activity by associating with these homo-oligomers without mediating their disassembly. We conclude that DFF nuclease is regulated by multiple pre- and post-activation fail-safe steps.
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Affiliation(s)
- Piotr Widlak
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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18
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Nagata S, Nagase H, Kawane K, Mukae N, Fukuyama H. Degradation of chromosomal DNA during apoptosis. Cell Death Differ 2003; 10:108-16. [PMID: 12655299 DOI: 10.1038/sj.cdd.4401161] [Citation(s) in RCA: 316] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Apoptosis is often accompanied by degradation of chromosomal DNA. CAD, caspase-activated DNase, was identified in 1998 as a DNase that is responsible for this process. In the last several years, mice deficient in the CAD system have been generated. Studies with these mice indicated that apoptotic DNA degradation occurs in two different systems. In one, the DNA fragmentation is carried out by CAD in the dying cells and in the other, by lysosomal DNase II after the dying cells are phagocytosed. Several other endonucleases have also been suggested as candidate effectors for the apoptotic degradation of chromosomal DNA. In this review, we will discuss the mechanism and role of DNA degradation during apoptosis.
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Affiliation(s)
- S Nagata
- Integrated Biology Laboratories, Graduate School of Frontier Science, Japan Science and Technology Corperation, Suita, Osaka.
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19
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Zhang J, McQuade JMS, Vorhees CV, Xu M. Hippocampal expression of c-fos is not essential for spatial learning. Synapse 2002; 46:91-9. [PMID: 12211087 DOI: 10.1002/syn.10115] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The formation of long-term memory is thought to involve underlying changes in synaptic strength. Many studies have focused on the mechanisms of spatial learning behavior in mammals that is critically dependent on the proper function of the hippocampus. Because of the enduring nature of long-term memory, it is thought that gene expression is involved in this process. The immediate early gene (IEG) c-fos encodes a transcription factor. The c-Fos proteins form heterodimeric proteins with the c-Jun family proteins and the resulting AP-1 transcription complex plays a key role in coupling short-term events elicited by stimuli received at the cell membrane to long-term neuroplastic changes by regulating gene expression. c-fos is induced in the hippocampus after spatial learning. Despite this knowledge, the precise role of c-fos in memory formation and the underlying mechanisms remain unknown. To start investigating the role of c-fos in learning and memory and underlying mechanisms, we evaluated spatial learning capabilities using mice carrying a hippocampal region-specific mutation of c-fos. We found that the c-fos mutant mice exhibit normal spatial learning behaviors in both the Morris water maze and the Barnes maze tests compared to control mice. Our results suggest that hippocampal c-fos expression is not essential for spatial learning.
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Affiliation(s)
- Jianhua Zhang
- Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
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20
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Abstract
DNA fragmentation is a hallmark of apoptosis. The tightly controlled activation of the apoptosis-specific endonucleases provides an effective means to ensure the removal of unwanted DNA and the timely completion of apoptosis. Over the past several years, crucial progress has been made in identifying the long-awaited apoptotic endonucleases, and their importance in tissue homeostasis is beginning to unfold. Here, we focus on the most recent discoveries about the functions and mechanisms of these endonucleases in the context of apoptosis. We also discuss consequences that defective DNA fragmentation might have for tissue homeostasis and disease development.
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Affiliation(s)
- Jianhua Zhang
- Dept of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0521, USA
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Zhang J, Lee H, Agarwala A, Wen Lou D, Xu M. Dna fragmentation factor 45 mutant mice exhibit resistance to kainic acid-induced neuronal cell death. Biochem Biophys Res Commun 2001; 285:1143-9. [PMID: 11478773 DOI: 10.1006/bbrc.2001.5313] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Excitotoxicity is a process where glutamate or other excitatory amino acids induce neuronal cell death. Emerging evidence suggests that apoptosis plays a key part in excitotoxic neurodegeneration. The DNA fragmentation factor 45 (DFF45 or ICAD) is a subunit of a heterodimeric DNase complex crucial for DNA fragmentation during apoptosis. Using a DFF45 mutant mouse model, we previously found that DFF45 deficient cells are more resistant to apoptosis than normal control cells. To investigate whether the lack of DFF45 may attenuate neuronal cell death induced by excitotoxicity, we compared kainic acid-induced seizure behavior and neuronal cell death in DFF45 mutant and wild-type control mice. We found that the mutant mice exhibit similar kainic acid-induced seizure severity compared to control mice. However, DFF45 mutant mice are more resistant than control mice to kainic acid-induced CA3 neuronal cell death. Interestingly, residual DNA degradation can be detected in the hippocampus of DFF45 mutant mice that exhibit KA-induced lesions. Our results suggest that a lack of DFF45 can lead to neuronal resistance to excessive activity-induced toxicity.
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Affiliation(s)
- J Zhang
- Department of Cell Biology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521, USA
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Yakovlev AG, Di X, Movsesyan V, Mullins PGM, Wang G, Boulares H, Zhang J, Xu M, Faden AI. Presence of DNA Fragmentation and Lack of Neuroprotective Effect in DFF45 Knockout Mice Subjected to Traumatic Brain Injury. Mol Med 2001. [DOI: 10.1007/bf03401955] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Abstract
Neuron production, migration and differentiation are major developmental events that continue, on a smaller scale, into adult life in a wide range of species from insects to mammals. Recent reports of adult neurogenesis in primates, including humans, have led to explosive scientific and public attention. During the last two years, significant discoveries have revealed that the generation, recruitment and survival of new neurons in adult brains are governed by principles similar to those that shape the developing brain, such as neuronal death, sensory experience, activity levels, and learning. Similarly, many factors implicated in embryonic neurogenesis are increasingly found to regulate adult neurogenesis and survival as well. These findings now allow the first manipulations of the numbers of adult-generated neurons to address their potential behavioral function.
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Affiliation(s)
- C Scharff
- The Rockefeller University, 1230 York Avenue Box 137, New York, NY 10021, USA.
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Abstract
Cleavage of chromosomal DNA into oligonucleosomal size fragments is an integral part of apoptosis. Elegant biochemical work identified the DNA fragmentation factor (DFF) as a major apoptotic endonuclease for DNA fragmentation in vitro. Genetic studies in mice support the importance of DFF in DNA fragmentation and possibly in apoptosis in vivo. Recent work also suggests the existence of additional endonucleases for DNA degradation. Understanding the roles of individual endonucleases in apoptosis, and how they might coordinate to degrade DNA in different tissues during normal development and homeostasis, as well as in various diseased states, will be a major research focus in the near future.
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Affiliation(s)
- J H Zhang
- Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, Ohio 45267-0521, USA
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Zhang J, Lee H, Lou DW, Bovin GP, Xu M. Lack of obvious 50 kilobase pair DNA fragments in DNA fragmentation factor 45-deficient thymocytes upon activation of apoptosis. Biochem Biophys Res Commun 2000; 274:225-9. [PMID: 10903922 DOI: 10.1006/bbrc.2000.3122] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The DNA fragmentation factor 45 (DFF45/ICAD) is a key subunit of a heterodimeric DNase complex critical for the induction of DNA fragmentation during apoptosis in vivo. To further assess the importance of DFF45 in chromosomal DNA degradation, we induced apoptosis in wild-type control and DFF45 deficient thymocytes and compared the cleavage of chromosomal DNA to 50 kilobase pair size fragments. We found that there is a lack of obvious large chromosomal DNA fragments upon treatments by various apoptotic agents in DFF45 deficient thymocytes. The major organ systems in the DFF45 mutant mice either two months or fifteen months of age appear normal. These results suggest that functional DFF45 is required for cleavage of DNA into both large size and oligonucleosomal size fragments in thymocytes during apoptosis. However, deficiency in DFF45 apparently does not significantly affect normal mouse development and tissue homeostasis.
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Affiliation(s)
- J Zhang
- Department of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0521, USA
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