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Modulation of SOD3 Levels Is Detrimental to Retinal Homeostasis. Antioxidants (Basel) 2021; 10:antiox10101595. [PMID: 34679728 PMCID: PMC8533566 DOI: 10.3390/antiox10101595] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/05/2021] [Accepted: 10/07/2021] [Indexed: 01/08/2023] Open
Abstract
Retinal oxidative stress is a common secondary feature of many retinal diseases. Though it may not be the initial insult, it is a major contributor to the pathogenesis of highly prevalent retinal dystrophic diseases like macular degeneration, diabetic retinopathy, and retinitis pigmentosa. We explored the role of superoxide dismutase 3 (SOD3) in retinal homeostasis since SOD3 protects the extracellular matrix (ECM) from oxidative injury. We show that SOD3 is mainly extracellularly localized and is upregulated as a result of environmental and pathogenic stress. Ablation of SOD3 resulted in reduced functional electroretinographic responses and number of photoreceptors, which is exacerbated with age. By contrast, overexpression showed increased electroretinographic responses and increased number of photoreceptors at young ages, but appears deleterious as the animal ages, as determined from the associated functional decline. Our exploration shows that SOD3 is vital to retinal homeostasis but its levels are tightly regulated. This suggests that SOD3 augmentation to combat oxidative stress during retinal degenerative changes may only be effective in the short-term.
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Li RF, Nan GX, Wang D, Gao C, Yang J, Zhang ZL. BMP9 Can Induce Schwann Cells Expressing Simian Virus 40 T Antigen to Differentiate into Fat and Bone In Vivo and In Vitro. Cell Reprogram 2021; 23:108-116. [PMID: 33861637 DOI: 10.1089/cell.2020.0069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In our previous study, we constructed Schwann cells (SCs) that stably express Simian virus 40 T antigen (SV40T-SCs). SV40T-SCs functions and markers are similar to those of neural crest cells. There we used bone morphogenetic protein 9 (BMP9) to induce SV40T-SCs differentiation in vitro and in vivo and study possible related mechanism. SV40T-SCs differentiation was induced by BMP9 conditioned medium. The lipogenic differentiation of SV40T-SCs was assessed by Oil Red O staining. Alizarin red and Alcian blue staining, and alkaline phosphatase (ALP) assays were used to evaluate the SV40T-SCs osteogenic differentiation. The expression of adipocyte differentiation (c/EBPα and c/EBPβ) and osteoblast differentiation markers (OSX and RUNX2) were detected by quantitative polymerase chain reaction (qPCR). To study possible mechanism related to SV40T-SCs differentiation, the P53 and E2F1 activity were assessed by luciferase reporter plasmid, and Slug and E-cadherin expression by qPCR. In vivo, SV40T-SCs infected by Ad-BMP9 or Ad-GFP were injected under the skin of nude mice. After 4-6 W, the mice were euthanized and subcutaneously mass formed at injecting sites was collected for pathological analysis. After SV40T-SCs were cultured in BMP9 conditioned medium, lipid droplets were formed in the cytoplasm of these cells. Alizarin red and Alcian blue staining were positive, and ALP activity of SV40T-SCs increased significantly. The expression of adipocyte differentiation (c/EBPα and c/EBPβ) and osteoblast differentiation markers (OSX and RUNX2) in SV40T-SCs was upregulated by BMP9. SV40T significantly increased Slug expression and decreased E-cadherin expression. SV40T-SCs infected with Ad-BMP9 were able to differentiate into adipose tissue and form a small bone matrix under the nude mice skin. SV40T-SCs have the ability to differentiate into adipocytes and osteoblasts in vivo and in vitro. SV40T can upregulate the Slug expression and downregulate the E-cadherin expression to produce endothelial-to-mesenchymal transition (EMT). The multidirectional differentiation ability of SV40T-SCs may be related to EMT.
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Affiliation(s)
- Rui-Fang Li
- Department of Neurology, Hubei NO.3 People's Hospital of Jianghan University, Wuhan, China
| | - Guo-Xin Nan
- Chongqing Key Laboratory of Pediatrics, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Department II of Orthopaedics, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Dan Wang
- Department of Neurology, Hubei NO.3 People's Hospital of Jianghan University, Wuhan, China
| | - Chang Gao
- Department of Neurology, Hubei NO.3 People's Hospital of Jianghan University, Wuhan, China
| | - Juan Yang
- Department of Neurology, Hubei NO.3 People's Hospital of Jianghan University, Wuhan, China
| | - Zhong-Lin Zhang
- Department of Hepatobiliary Surgery, Zhongnan Hospital of Wuhan University, Wuhan, China
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3
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Aggio-Bruce R, Chu-Tan JA, Wooff Y, Cioanca AV, Schumann U, Natoli R. Inhibition of microRNA-155 Protects Retinal Function Through Attenuation of Inflammation in Retinal Degeneration. Mol Neurobiol 2021; 58:835-854. [PMID: 33037565 PMCID: PMC7843561 DOI: 10.1007/s12035-020-02158-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/01/2020] [Indexed: 01/14/2023]
Abstract
Although extensively investigated in inflammatory conditions, the role of pro-inflammatory microRNAs (miRNAs), miR-155 and miR-146a, has not been well-studied in retinal degenerative diseases. We therefore aimed to explore the role and regulation of these miRNA in the degenerating retina, with a focus on miR-155. C57BL/6J mice were subjected to photo-oxidative damage for up to 5 days to induce focal retinal degeneration. MiR-155 expression was quantified by qRT-PCR in whole retina, serum, and small-medium extracellular vesicles (s-mEVs), and a PrimeFlow™ assay was used to identify localisation of miR-155 in retinal cells. Constitutive miR-155 knockout (KO) mice and miR-155 and miR-146a inhibitors were utilised to determine the role of these miRNA in the degenerating retina. Electroretinography was employed as a measure of retinal function, while histological quantification of TUNEL+ and IBA1+ positive cells was used to quantify photoreceptor cell death and infiltrating immune cells, respectively. Upregulation of miR-155 was detected in retinal tissue, serum and s-mEVs in response to photo-oxidative damage, localising to the nucleus of a subset of retinal ganglion cells and glial cells and in the cytoplasm of photoreceptors. Inhibition of miR-155 showed increased function from negative controls and a less pathological pattern of IBA1+ cell localisation and morphology at 5 days photo-oxidative damage. While neither dim-reared nor damaged miR-155 KO animals showed retinal histological difference from controls, following photo-oxidative damage, miR-155 KO mice showed increased a-wave relative to controls. We therefore consider miR-155 to be associated with the inflammatory response of the retina in response to photoreceptor-specific degeneration.
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Affiliation(s)
- Riemke Aggio-Bruce
- The John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, Australian Capital Territory 2601 Australia
- The Australian National University Medical School, Mills Road, Australian Capital Territory, Acton, 2601 Australia
| | - Joshua A. Chu-Tan
- The John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, Australian Capital Territory 2601 Australia
- The Australian National University Medical School, Mills Road, Australian Capital Territory, Acton, 2601 Australia
| | - Yvette Wooff
- The John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, Australian Capital Territory 2601 Australia
- The Australian National University Medical School, Mills Road, Australian Capital Territory, Acton, 2601 Australia
| | - Adrian V. Cioanca
- The John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, Australian Capital Territory 2601 Australia
| | - Ulrike Schumann
- The John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, Australian Capital Territory 2601 Australia
| | - Riccardo Natoli
- The John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, Australian Capital Territory 2601 Australia
- The Australian National University Medical School, Mills Road, Australian Capital Territory, Acton, 2601 Australia
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4
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Bonnin EA, Fornasiero EF, Lange F, Turck CW, Rizzoli SO. NanoSIMS observations of mouse retinal cells reveal strict metabolic controls on nitrogen turnover. BMC Mol Cell Biol 2021; 22:5. [PMID: 33430763 PMCID: PMC7798281 DOI: 10.1186/s12860-020-00339-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 12/17/2020] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Most of the cells of the mammalian retina are terminally differentiated, and do not regenerate once fully developed. This implies that these cells have strict controls over their metabolic processes, including protein turnover. We report the use of metabolic labelling procedures and secondary ion mass spectrometry imaging to examine nitrogen turnover in retinal cells, with a focus on the outer nuclear layer, inner nuclear layer, and outer plexiform layer. RESULTS We find that turnover can be observed in all cells imaged using NanoSIMS. However, the rate of turnover is not constant, but varies between different cellular types and cell regions. In the inner and outer nuclear layers, turnover rate is higher in the cytosol than in the nucleus of each cell. Turnover rates are also higher in the outer plexiform layer. An examination of retinal cells from mice that were isotopically labeled very early in embryonic development shows that proteins produced during this period can be found in all cells and cell regions up to 2 months after birth, even in regions of high turnover. CONCLUSIONS Our results indicate that turnover in retinal cells is a highly regulated process, with strict metabolic controls. We also observe that turnover is several-fold higher in the synaptic layer than in cell layers. Nevertheless, embryonic proteins can still be found in this layer 2 months after birth, suggesting that stable structures persist within the synapses, which remain to be determined.
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Affiliation(s)
- Elisa A Bonnin
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073, Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration (BIN), 37075, Göttingen, Germany.
| | - Eugenio F Fornasiero
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), 37075, Göttingen, Germany
| | - Felix Lange
- Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, 37077, Göttingen, Germany
- Clinic for Neurology, University Medical Center Göttingen, 37075, Göttingen, Germany
| | - Christoph W Turck
- Proteomics and Biomarkers, Max Planck Institute of Psychiatry, Munich, Germany
| | - Silvio O Rizzoli
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Excellence Cluster Multiscale Bioimaging, 37073, Göttingen, Germany
- Center for Biostructural Imaging of Neurodegeneration (BIN), 37075, Göttingen, Germany
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5
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Barrett T, Stangis KA, Saito T, Saido T, Park KH. Neuronal Cell Cycle Re-Entry Enhances Neuropathological Features in AppNLF Knock-In Mice. J Alzheimers Dis 2021; 82:1683-1702. [PMID: 34219712 PMCID: PMC8461670 DOI: 10.3233/jad-210091] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2021] [Indexed: 01/02/2023]
Abstract
BACKGROUND Aberrant cell cycle re-entry is a well-documented process occurring early in Alzheimer's disease (AD). This is an early feature of the disease and may contribute to disease pathogenesis. OBJECTIVE To assess the effect of forced neuronal cell cycle re-entry in mice expressing humanized Aβ, we crossed our neuronal cell cycle re-entry mouse model with AppNLF knock-in (KI) mice. METHODS Our neuronal cell cycle re-entry (NCCR) mouse model is bitransgenic mice heterozygous for both Camk2a-tTA and TRE-SV40T. The NCCR mice were crossed with AppNLF KI mice to generate NCCR-AppNLF animals. Using this tet-off system, we triggered NCCR in our animals via neuronal expression of SV40T starting at 1 month of age. The animals were examined at the following time points: 9, 12, and 18 months of age. Various neuropathological features in our mice were evaluated by image analysis and stereology on brain sections stained using either immunofluorescence or immunohistochemistry. RESULTS We show that neuronal cell cycle re-entry in humanized Aβ plaque producing AppNLF KI mice results in the development of additional AD-related pathologies, namely, pathological tau, neuroinflammation, brain leukocyte infiltration, DNA damage response, and neurodegeneration. CONCLUSION Our findings show that neuronal cell cycle re-entry enhances AD-related neuropathological features in AppNLF mice and highlight our unique AD mouse model for studying the pathogenic role of aberrant cell cycle re-entry in AD.
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Affiliation(s)
- Tomás Barrett
- Neuroscience Program, Central Michigan University, Mount Pleasant, MI, USA
| | | | - Takashi Saito
- Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Takaomi Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Wako, Saitama, Japan
| | - Kevin H.J. Park
- Neuroscience Program, Central Michigan University, Mount Pleasant, MI, USA
- Department of Psychology, Central Michigan University, Mount Pleasant, MI, USA
- Biochemistry, Cellular & Molecular Biology Graduate Program, Central Michigan University, Mount Pleasant, MI, USA
- Michigan Alzheimer’s Disease Research Center, University of Michigan, Ann Arbor, MI, USA
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6
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Potic J, Mbefo M, Berger A, Nicolas M, Wanner D, Kostic C, Matet A, Behar-Cohen F, Moulin A, Arsenijevic Y. An in vitro Model of Human Retinal Detachment Reveals Successive Death Pathway Activations. Front Neurosci 2020; 14:571293. [PMID: 33324144 PMCID: PMC7726250 DOI: 10.3389/fnins.2020.571293] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/29/2020] [Indexed: 01/30/2023] Open
Abstract
Purpose was to create an in vitro model of human retinal detachment (RD) to study the mechanisms of photoreceptor death. Methods Human retinas were obtained through eye globe donations for research purposes and cultivated as explants. Cell death was investigated in retinas with (control) and without retinal pigment epithelium (RPE) cells to mimic RD. Tissues were studied at different time points and immunohistological analyses for TUNEL, Cleaved caspase3, AIF, CDK4 and the epigenetic mark H3K27me3 were performed. Human and monkey eye globes with retinal detachment served as controls. Results The number of TUNEL-positive cells, compared between 1 and 7 days, increased with time in both retinas with RPE (from 1.2 ± 0.46 to 8 ± 0.89, n = 4) and without RPE (from 2.6 ± 0.73 to 16.3 ± 1.27, p < 0.014). In the group without RPE, cell death peaked at day 3 (p = 0.014) and was high until day 7. Almost no Cleaved-Caspase3 signal was observed, whereas a transient augmentation at day 3 of AIF-positive cells was observed to be about 10-fold in comparison to the control group (n = 2). Few CDK4-positive cells were found in both groups, but significantly more in the RD group at day 7 (1.8 ± 0.24 vs. 4.7 ± 0.58, p = 0.014). The H3K27me3 mark increased by 7-fold after 5 days in the RD group (p = 0.014) and slightly decreased at day 7 and was also observed to be markedly increased in human and monkey detached retina samples. Conclusion AIF expression coincides with the first peak of cell death, whereas the H3K27me3 mark increases during the cell death plateau, suggesting that photoreceptor death is induced by different successive pathways after RD. This in vitro model should permit the identification of neuroprotective drugs with clinical relevance.
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Affiliation(s)
- Jelena Potic
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland.,Clinic for Eye Diseases, Clinical Center of Serbia, Belgrade, Serbia.,Department of Ophthalmology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Martial Mbefo
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Adeline Berger
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Michael Nicolas
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Dana Wanner
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Corinne Kostic
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Alexandre Matet
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland.,Department of Ophthalmology, Institut Curie, Université de Paris, Paris, France
| | - Francine Behar-Cohen
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland.,INSERM U 1138, Centre de Recherches des Cordeliers, Université Paris Descartes, Université Pierre et Marie Curie, Paris, France
| | - Alexandre Moulin
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
| | - Yvan Arsenijevic
- Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, Lausanne, Switzerland
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7
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Nakamura S, Maoka T, Kuse Y, Muramatsu A, Yoshino Y, Shimazawa M, Hara H. Distribution of Carotenoids and Protective Effects of Zeaxanthin on Retina of Ayu Sweetfish (Plecoglossus altivelis). J Oleo Sci 2020; 69:1095-1105. [PMID: 32788523 DOI: 10.5650/jos.ess20108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ayu sweetfish (Plecoglossus altivelis) is a diurnal freshwater fish that are surface swimmers and active under broad and short wavelength-dominated light. Biochemical analyses have shown that the ayu fish have abundant carotenoids including zeaxanthin in their integuments. Although zeaxanthin plays an important role in the physiological function of the retina, the amount and location of zeaxanthin in the ayu eye have not been accurately determined. In this study, circular dichroism spectral data and chiral high-performance liquid chromatography analysis showed that zeaxanthin was the primary carotenoid in the ayu eye, and the eye had the highest carotenoid content compared to those in the integuments, subcutaneous fat, and digestive tract. Interestingly, zeaxanthin in the ayu eyeball was expressed in the photoreceptor layer and near the retinal pigmented epithelium. In vitro assays showed that zeaxanthin could protect photoreceptors and retinal pigmented epithelial cell lines against the oxidative stress induced by exposure to L-buthionine-(S,R)-sulfoximine/glutamate. These findings indicate that zeaxanthin plays protective roles against oxidative stress in the vision of wild ayu.
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Affiliation(s)
- Shinsuke Nakamura
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University
| | - Takashi Maoka
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, JAPAN Research Institute for Production Development Division of Food Function and Chemistry
| | - Yoshiki Kuse
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University
| | - Aomi Muramatsu
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University
| | - Yuta Yoshino
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University
| | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University
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Ikelle L, Al-Ubaidi MR, Naash MI. Pluripotent Stem Cells for the Treatment of Retinal Degeneration: Current Strategies and Future Directions. Front Cell Dev Biol 2020; 8:743. [PMID: 32923439 PMCID: PMC7457054 DOI: 10.3389/fcell.2020.00743] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/16/2020] [Indexed: 01/14/2023] Open
Abstract
Stem cells have been part of the biomedical landscape since the early 1960s. However, the translation of stem cells to effective therapeutics have met significant challenges, especially for retinal diseases. The retina is a delicate and complex architecture of interconnected cells that are steadfastly interdependent. Degenerative mechanisms caused by acquired or inherited diseases disrupt this interconnectivity, devastating the retina and causing severe vision loss in many patients. Consequently, retinal differentiation of exogenous and endogenous stem cells is currently being explored as replacement therapies in the debilitating diseases. In this review, we will examine the mechanisms involved in exogenous stem cells differentiation and the challenges of effective integration to the host retina. Furthermore, we will explore the current advancements in trans-differentiation of endogenous stem cells, primarily Müller glia.
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Affiliation(s)
- Larissa Ikelle
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
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9
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Wooff Y, Cioanca AV, Chu-Tan JA, Aggio-Bruce R, Schumann U, Natoli R. Small-Medium Extracellular Vesicles and Their miRNA Cargo in Retinal Health and Degeneration: Mediators of Homeostasis, and Vehicles for Targeted Gene Therapy. Front Cell Neurosci 2020; 14:160. [PMID: 32670023 PMCID: PMC7330137 DOI: 10.3389/fncel.2020.00160] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 05/13/2020] [Indexed: 12/12/2022] Open
Abstract
Photoreceptor cell death and inflammation are known to occur progressively in retinal degenerative diseases such as age-related macular degeneration (AMD). However, the molecular mechanisms underlying these biological processes are largely unknown. Extracellular vesicles (EV) are essential mediators of cell-to-cell communication with emerging roles in the modulation of immune responses. EVs, including exosomes, encapsulate and transfer microRNA (miRNA) to recipient cells and in this way can modulate the environment of recipient cells. Dysregulation of EVs however is correlated to a loss of cellular homeostasis and increased inflammation. In this work we investigated the role of isolated retinal small-medium sized EV (s-mEV) which includes exosomes in both the healthy and degenerating retina. Isolated s-mEV from normal retinas were characterized using dynamic light scattering, transmission electron microscopy and western blotting, and quantified across 5 days of photo-oxidative damage-induced degeneration using nanotracking analysis. Small RNAseq was used to characterize the miRNA cargo of retinal s-mEV isolated from healthy and damaged retinas. Finally, the effect of exosome inhibition on cell-to-cell miRNA transfer and immune modulation was conducted using systemic daily administration of exosome inhibitor GW4869 and in situ hybridization of s-mEV-abundant miRNA, miR-124-3p. Electroretinography and immunohistochemistry was performed to assess functional and morphological changes to the retina as a result of GW4869-induced exosome depletion. Results demonstrated an inverse correlation between s-mEV concentration and photoreceptor survivability, with a decrease in s-mEV numbers following degeneration. Small RNAseq revealed that s-mEVs contained uniquely enriched miRNAs in comparison to in whole retinal tissue, however, there was no differential change in the s-mEV miRNAnome following photo-oxidative damage. Exosome inhibition via the use of GW4869 was also found to exacerbate retinal degeneration, with reduced retinal function and increased levels of inflammation and cell death demonstrated following photo-oxidative damage in exosome-inhibited mice. Further, GW4869-treated mice displayed impaired translocation of photoreceptor-derived miR-124-3p to the inner retina during damage. Taken together, we propose that retinal s-mEV and their miRNA cargo play an essential role in maintaining retinal homeostasis through immune-modulation, and have the potential to be used in targeted gene therapy for retinal degenerative diseases.
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Affiliation(s)
- Yvette Wooff
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,The ANU Medical School, The Australian National University, Canberra, ACT, Australia
| | - Adrian V Cioanca
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Joshua A Chu-Tan
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,The ANU Medical School, The Australian National University, Canberra, ACT, Australia
| | - Riemke Aggio-Bruce
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,The ANU Medical School, The Australian National University, Canberra, ACT, Australia
| | - Ulrike Schumann
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Riccardo Natoli
- The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,The ANU Medical School, The Australian National University, Canberra, ACT, Australia
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10
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Zhang Y, Song X, Herrup K. Context-Dependent Functions of E2F1: Cell Cycle, Cell Death, and DNA Damage Repair in Cortical Neurons. Mol Neurobiol 2020; 57:2377-2390. [PMID: 32062842 DOI: 10.1007/s12035-020-01887-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/29/2020] [Indexed: 01/17/2023]
Abstract
DNA damage has been reported to induce cell cycle-related neuronal death. This is significant as aberrant cell cycle re-entry of mature, post-mitotic neurons contributes to neurodegeneration. In this study, we investigate how DNA damage elicited by exposure to the topoisomerase I inhibitor camptothecin (CPT) leads to cycle-related death of cultured cortical neurons and examine the function of E2F1 in this process. CPT treatment induced cell cycle initiation of cortical neurons and elevated the expression of certain cell cycle components (e.g., cyclin D1, CDK4, E2F1) but failed to drive S phase entry or DNA synthesis. The arrest in the cell cycle is explained by the elevated expression of the CDK inhibitor p21Cip1. Though its level was increased after CPT treatment, E2F1 did not drive treated neurons into the G1-S phase transition. E2F1 overexpression led to cell cycle activation and acute neuronal apoptosis without detectable entry of the neurons into S phase. ChIPseq analysis demonstrated that E2F1 predominantly occupies positions on or near the promoters of cell cycle related genes. Instead, in CPT-treated neurons, E2F1 preferentially regulated DNA repair related genes. Our study reveals that the functions of E2F1 in postmitotic neurons are context-dependent and offers novel insights into the role of E2F1 in DNA damage induced cycle-related neuronal death.
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Affiliation(s)
- Yang Zhang
- Division of Life Science and the State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Xuan Song
- Division of Life Science and the State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - Karl Herrup
- Division of Life Science and the State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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11
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Caspase-1-dependent inflammasomes mediate photoreceptor cell death in photo-oxidative damage-induced retinal degeneration. Sci Rep 2020; 10:2263. [PMID: 32041990 PMCID: PMC7010818 DOI: 10.1038/s41598-020-58849-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 01/06/2020] [Indexed: 01/14/2023] Open
Abstract
Activation of the inflammasome is involved in the progression of retinal degenerative diseases, in particular, in the pathogenesis of Age-Related Macular Degeneration (AMD), with NLRP3 activation the focus of many investigations. In this study, we used genetic and pharmacological approaches to explore the role of the inflammasome in a mouse model of retinal degeneration. We identify that Casp1/11−/− mice have better-preserved retinal function, reduced inflammation and increased photoreceptor survivability. While Nlrp3−/− mice display some level of preservation of retinal function compared to controls, pharmacological inhibition of NLRP3 did not protect against photoreceptor cell death. Further, Aim2−/−, Nlrc4−/−, Asc−/−, and Casp11−/− mice show no substantial retinal protection. We propose that CASP-1-associated photoreceptor cell death occurs largely independently of NLRP3 and other established inflammasome sensor proteins, or that inhibition of a single sensor is not sufficient to repress the inflammatory cascade. Therapeutic targeting of CASP-1 may offer a more promising avenue to delay the progression of retinal degenerations.
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12
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Mencl S, Trifunović D, Zrenner E, Paquet-Durand F. PKG-Dependent Cell Death in 661W Cone Photoreceptor-like Cell Cultures (Experimental Study). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1074:511-517. [PMID: 29721983 DOI: 10.1007/978-3-319-75402-4_63] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In humans cone photoreceptors are responsible for high-resolution colour vision. A variety of retinal diseases can compromise cone viability, and, at present, no satisfactory treatment options are available. Here, we present data towards establishing a reliable, high-throughput assay system that will facilitate the search for cone neuroprotective compounds using the murine-photoreceptor cell line 661 W. To further characterize 661 W cells, a retinal marker study was performed, followed by the induction of cell death using paradigms over-activating cGMP-dependent protein kinase G (PKG). We found that 661 W cells may be used to mimic specific aspects of cone degeneration and may thus be valuable for future compound screening studies.
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Affiliation(s)
- Stine Mencl
- University Hospital Essen, Department of Neurology, Essen, Germany
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Dragana Trifunović
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Eberhart Zrenner
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany
- Centre for Integrative Neuroscience (CIN), Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - François Paquet-Durand
- Department für Augenheilkunde, Forschungsinstitut für Augenheilkunde, Eberhard Karls Universität Tübingen, Tübingen, Germany.
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13
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Dent MAR, Aranda-Anzaldo A. Lessons we can learn from neurons to make cancer cells quiescent. J Neurosci Res 2019; 97:1141-1152. [PMID: 30985022 DOI: 10.1002/jnr.24428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 02/20/2019] [Accepted: 03/26/2019] [Indexed: 12/16/2022]
Abstract
Cancer is a major concern for contemporary societies. However, the incidence of cancer is unevenly distributed among tissues and cell types. In particular, the evidence indicates that neurons are absolutely resistant to cancer and this is commonly explained on the basis of the known postmitotic state of neurons. The dominant paradigm on cancer understands this problem as a disease caused by mutations in cellular genes that result in unrestrained cell proliferation and eventually in tissue invasion and metastasis. However, the evidence also shows that mutations and gross chromosomal anomalies are common in functional neurons that nevertheless do not become neoplastic. This fact suggests that in the real nonexperimental setting mutations per se are not enough for inducing carcinogenesis but also that the postmitotic state of neurons is not genetically controlled or determined, otherwise there should be reports of spontaneously transformed neurons. Here we discuss the evidence that the postmitotic state of neurons has a structural basis on the high stability of their nuclear higher order structure that performs like an absolute tumor suppressor. We also discuss evidence that it is possible to induce a similar structural postmitotic state in nonneural cell types as a practical strategy for stopping or reducing the progression of cancer.
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Affiliation(s)
- Myrna A R Dent
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Mexico
| | - Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Mexico
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14
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Abstract
Differentiated neurons can undergo cell cycle re-entry during pathological conditions, but it remains largely accepted that M-phase is prohibited in these cells. Here we show that primary neurons at post-synaptogenesis stages of development can enter M-phase. We induced cell cycle re-entry by overexpressing a truncated Cyclin E isoform fused to Cdk2. Cyclin E/Cdk2 expression elicits canonical cell cycle checkpoints, which arrest cell cycle progression and trigger apoptosis. As in mitotic cells, checkpoint abrogation enables cell cycle progression through S and G2-phases into M-phase. Although most neurons enter M-phase, only a small subset undergo cell division. Alternatively, neurons can exit M-phase without cell division and recover the axon initial segment, a structural determinant of neuronal viability. We conclude that neurons and mitotic cells share S, G2 and M-phase regulation.
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15
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Barrio-Alonso E, Hernández-Vivanco A, Walton CC, Perea G, Frade JM. Cell cycle reentry triggers hyperploidization and synaptic dysfunction followed by delayed cell death in differentiated cortical neurons. Sci Rep 2018; 8:14316. [PMID: 30254284 PMCID: PMC6156334 DOI: 10.1038/s41598-018-32708-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 09/14/2018] [Indexed: 11/09/2022] Open
Abstract
Cell cycle reentry followed by neuronal hyperploidy and synaptic failure are two early hallmarks of Alzheimer's disease (AD), however their functional connection remains unexplored. To address this question, we induced cell cycle reentry in cultured cortical neurons by expressing SV40 large T antigen. Cell cycle reentry was followed by hyperploidy in ~70% of cortical neurons, and led to progressive axon initial segment loss and reduced density of dendritic PSD-95 puncta, which correlated with diminished spike generation and reduced spontaneous synaptic activity. This manipulation also resulted in delayed cell death, as previously observed in AD-affected hyperploid neurons. Membrane depolarization by high extracellular potassium maintained PSD-95 puncta density and partially rescued both spontaneous synaptic activity and cell death, while spike generation remained blocked. This suggests that AD-associated hyperploid neurons can be sustained in vivo if integrated in active neuronal circuits whilst promoting synaptic dysfunction. Thus, cell cycle reentry might contribute to cognitive impairment in early stages of AD and neuronal death susceptibility at late stages.
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Affiliation(s)
- E Barrio-Alonso
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute (CSIC), Madrid, Spain
| | - A Hernández-Vivanco
- Department of Functional and Systems Neurobiology, Cajal Institute (CSIC), Madrid, Spain
| | - C C Walton
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute (CSIC), Madrid, Spain
| | - G Perea
- Department of Functional and Systems Neurobiology, Cajal Institute (CSIC), Madrid, Spain
| | - J M Frade
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute (CSIC), Madrid, Spain.
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16
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Oshikawa M, Okada K, Tabata H, Nagata KI, Ajioka I. Dnmt1-dependent Chk1 pathway suppression is protective against neuron division. Development 2017; 144:3303-3314. [PMID: 28928282 DOI: 10.1242/dev.154013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Accepted: 08/01/2017] [Indexed: 12/19/2022]
Abstract
Neuronal differentiation and cell-cycle exit are tightly coordinated, even in pathological situations. When pathological neurons re-enter the cell cycle and progress through the S phase, they undergo cell death instead of division. However, the mechanisms underlying mitotic resistance are mostly unknown. Here, we have found that acute inactivation of retinoblastoma (Rb) family proteins (Rb, p107 and p130) in mouse postmitotic neurons leads to cell death after S-phase progression. Checkpoint kinase 1 (Chk1) pathway activation during the S phase prevented the cell death, and allowed the division of cortical neurons that had undergone acute Rb family inactivation, oxygen-glucose deprivation (OGD) or in vivo hypoxia-ischemia. During neurogenesis, cortical neurons became protected from S-phase Chk1 pathway activation by the DNA methyltransferase Dnmt1, and underwent cell death after S-phase progression. Our results indicate that Chk1 pathway activation overrides mitotic safeguards and uncouples neuronal differentiation from mitotic resistance.
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Affiliation(s)
- Mio Oshikawa
- Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan
| | - Kei Okada
- Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan
| | - Hidenori Tabata
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai Aichi 480-0392, Japan
| | - Koh-Ichi Nagata
- Department of Molecular Neurobiology, Institute for Developmental Research, Aichi Human Service Center, Kasugai Aichi 480-0392, Japan
| | - Itsuki Ajioka
- Center for Brain Integration Research (CBIR), Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan .,The Japan Science and Technology Agency (JST), Precursory Research for Embryonic Science and Technology (PRESTO), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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17
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Abstract
The SV40 viral oncogene has been used since the 1970s as a reliable and reproducible method to generate transgenic mouse models. This seminal discovery has taught us an immense amount about how tumorigenesis occurs, and its success has led to the evolution of many mouse models of cancer. Despite the development of more modern and targeted approaches for developing genetically engineered mouse models of cancer, SV40-induced mouse models still remain frequently used today. This review discusses a number of cancer types in which SV40 mouse models of cancer have been developed and highlights their relevance and importance to preclinical research.
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Affiliation(s)
- Amanda L Hudson
- Amanda L. Hudson, PhD, is a Sydney Neuro-Oncology Group postdoctoral fellow at the Bill Walsh Translational Cancer Research Laboratory, Kolling Institute, Northern Sydney Local Health District, Sydney Medical School Northern, University of Sydney, St. Leonards, NSW, Australia. Emily K. Colvin is a Cancer Institute NSW postdoctoral fellow at the Bill Walsh Translational Cancer Research Laboratory, Kolling Institute, Northern Sydney Local Health District, Sydney Medical School Northern, University of Sydney, St. Leonards, NSW, Australia
| | - Emily K Colvin
- Amanda L. Hudson, PhD, is a Sydney Neuro-Oncology Group postdoctoral fellow at the Bill Walsh Translational Cancer Research Laboratory, Kolling Institute, Northern Sydney Local Health District, Sydney Medical School Northern, University of Sydney, St. Leonards, NSW, Australia. Emily K. Colvin is a Cancer Institute NSW postdoctoral fellow at the Bill Walsh Translational Cancer Research Laboratory, Kolling Institute, Northern Sydney Local Health District, Sydney Medical School Northern, University of Sydney, St. Leonards, NSW, Australia
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18
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The hippocampal cyclin D1 expression is involved in postoperative cognitive dysfunction after sevoflurane exposure in aged mice. Life Sci 2016; 160:34-40. [DOI: 10.1016/j.lfs.2016.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 07/05/2016] [Accepted: 07/10/2016] [Indexed: 01/08/2023]
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19
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Aranda-Anzaldo A, Dent MAR. Why Cortical Neurons Cannot Divide, and Why Do They Usually Die in the Attempt? J Neurosci Res 2016; 95:921-929. [PMID: 27402311 DOI: 10.1002/jnr.23765] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/25/2016] [Accepted: 04/25/2016] [Indexed: 12/19/2022]
Abstract
Cortical neurons are prime examples of terminally differentiated, postmitotic cells. However, under experimental or pathological conditions, they can re-enter the cell cycle and replicate DNA but are unable to divide, dying by apoptosis or becoming either polyploid or aneuploid. Any cellular state that depends on the action of genes and their products can be reverted or bypassed by spontaneous or induced mutations, yet there are currently no reports of dividing cortical neurons. Thus, it seems unlikely that the remarkably stable postmitotic condition of cortical neurons depends on specific gene functions. This Review summarizes evidence that the postmitotic state of cortical neurons depends on the high stability of its underlying nuclear structure that results from an entropy-driven process aimed at dissipating the intrinsic structural stress present in chromosomal DNA in such a way that the structural stability of the neuronal nucleus becomes an insurmountable energy barrier for karyokinesis and mitosis. From this perspective, the integral properties of the nuclear higher order structure in neurons provide an explanation not only for why cortical neurons cannot divide but also for why they usually die if they happen to replicate their DNA. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado México, México
| | - Myrna A R Dent
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado México, México
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20
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Cortical neurons gradually attain a post-mitotic state. Cell Res 2016; 26:1033-47. [PMID: 27325298 DOI: 10.1038/cr.2016.76] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 02/26/2016] [Accepted: 04/13/2016] [Indexed: 12/21/2022] Open
Abstract
Once generated, neurons are thought to permanently exit the cell cycle and become irreversibly differentiated. However, neither the precise point at which this post-mitotic state is attained nor the extent of its irreversibility is clearly defined. Here we report that newly born neurons from the upper layers of the mouse cortex, despite initiating axon and dendrite elongation, continue to drive gene expression from the neural progenitor tubulin α1 promoter (Tα1p). These observations suggest an ambiguous post-mitotic neuronal state. Whole transcriptome analysis of sorted upper cortical neurons further revealed that neurons continue to express genes related to cell cycle progression long after mitotic exit until at least post-natal day 3 (P3). These genes are however down-regulated thereafter, associated with a concomitant up-regulation of tumor suppressors at P5. Interestingly, newly born neurons located in the cortical plate (CP) at embryonic day 18-19 (E18-E19) and P3 challenged with calcium influx are found in S/G2/M phases of the cell cycle, and still able to undergo division at E18-E19 but not at P3. At P5 however, calcium influx becomes neurotoxic and leads instead to neuronal loss. Our data delineate an unexpected flexibility of cell cycle control in early born neurons, and describe how neurons transit to a post-mitotic state.
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21
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Tokarz P, Kaarniranta K, Blasiak J. Role of the Cell Cycle Re-Initiation in DNA Damage Response of Post-Mitotic Cells and Its Implication in the Pathogenesis of Neurodegenerative Diseases. Rejuvenation Res 2016. [DOI: 10.1089/rej.2015.1717] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Paulina Tokarz
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska, Lodz, Poland
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
- Department of Ophthalmology, Kuopio University Hospital, Kuopio, Finland
| | - Janusz Blasiak
- Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska, Lodz, Poland
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22
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Bhaskar K, Maphis N, Xu G, Varvel NH, Kokiko-Cochran ON, Weick JP, Staugaitis SM, Cardona A, Ransohoff RM, Herrup K, Lamb BT. Microglial derived tumor necrosis factor-α drives Alzheimer's disease-related neuronal cell cycle events. Neurobiol Dis 2013; 62:273-85. [PMID: 24141019 DOI: 10.1016/j.nbd.2013.10.007] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2013] [Revised: 10/01/2013] [Accepted: 10/06/2013] [Indexed: 01/06/2023] Open
Abstract
Massive neuronal loss is a key pathological hallmark of Alzheimer's disease (AD). However, the mechanisms are still unclear. Here we demonstrate that neuroinflammation, cell autonomous to microglia, is capable of inducing neuronal cell cycle events (CCEs), which are toxic for terminally differentiated neurons. First, oligomeric amyloid-beta peptide (AβO)-mediated microglial activation induced neuronal CCEs via the tumor-necrosis factor-α (TNFα) and the c-Jun Kinase (JNK) signaling pathway. Second, adoptive transfer of CD11b+ microglia from AD transgenic mice (R1.40) induced neuronal cyclin D1 expression via TNFα signaling pathway. Third, genetic deficiency of TNFα in R1.40 mice (R1.40-Tnfα(-/-)) failed to induce neuronal CCEs. Finally, the mitotically active neurons spatially co-exist with F4/80+ activated microglia in the human AD brain and that a portion of these neurons are apoptotic. Together our data suggest a cell-autonomous role of microglia, and identify TNFα as the responsible cytokine, in promoting neuronal CCEs in the pathogenesis of AD.
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Affiliation(s)
- Kiran Bhaskar
- Department of Molecular Genetics and Microbiology, University of New Mexico, MSC08 4660, 1 University of New Mexico, Albuquerque, NM 87131, USA.
| | - Nicole Maphis
- Department of Molecular Genetics and Microbiology, University of New Mexico, MSC08 4660, 1 University of New Mexico, Albuquerque, NM 87131, USA.
| | - Guixiang Xu
- Department of Neurosciences, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
| | - Nicholas H Varvel
- Department of Cellular Neurology, University of Tübingen, Hertie Institute for Clinical Brain Research, Otfried-Müller-Straße 27, 72076 Tübingen, Germany.
| | - Olga N Kokiko-Cochran
- Department of Neurosciences, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
| | - Jason P Weick
- Department of Neurosciences, University of New Mexico, MSC08 4740, 1 University of New Mexico, Albuquerque, NM 87131, USA.
| | - Susan M Staugaitis
- Department of Neurosciences, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
| | - Astrid Cardona
- Department of Biology, University of Texas San Antonio, West Campus/Tobin lab MBT 1.216, San Antonio, TX 78249, USA.
| | - Richard M Ransohoff
- Department of Neurosciences, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
| | - Karl Herrup
- Department of Cell Biology and Neuroscience, Rutgers University, Nelson Hall, Busch Campus, Piscataway, NJ 08855, USA.
| | - Bruce T Lamb
- Department of Neurosciences, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
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23
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Herrup K. ATM and the epigenetics of the neuronal genome. Mech Ageing Dev 2013; 134:434-9. [PMID: 23707635 DOI: 10.1016/j.mad.2013.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/01/2013] [Accepted: 05/17/2013] [Indexed: 01/28/2023]
Abstract
Ataxia-telangiectasia (A-T) is a neurodegenerative syndrome caused by the mutation of the ATM gene. The ATM protein is a PI3kinase family member best known for its role in the DNA damage response. While repair of DNA damage is a critical function that every CNS neuron must perform, a growing body of evidence indicates that the full range of ATM functions includes some that are unrelated to DNA damage yet are essential to neuronal survival and normal function. For example, ATM participates in the regulation of synaptic vesicle trafficking and is essential for the maintenance of normal LTP. In addition ATM helps to ensure the cytoplasmic localization of HDAC4 and thus maintains the histone 'code' of the neuronal genome by suppressing genome-wide histone deacetylation, which alters the message and protein levels of many genes that are important for neuronal survival and function. The growing list of ATM functions that go beyond its role in the DNA damage response offers a new perspective on why individuals with A-T express such a wide range of neurological symptoms, and suggests that not all A-T symptoms need to be understood in the context of the DNA repair process.
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Affiliation(s)
- Karl Herrup
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, United States; Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
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24
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Oshikawa M, Okada K, Nakajima K, Ajioka I. Cortical excitatory neurons become protected from cell division during neurogenesis in an Rb family-dependent manner. Development 2013; 140:2310-20. [PMID: 23615279 DOI: 10.1242/dev.095653] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell cycle dysregulation leads to abnormal proliferation and cell death in a context-specific manner. Cell cycle progression driven via the Rb pathway forces neurons to undergo S-phase, resulting in cell death associated with the progression of neuronal degeneration. Nevertheless, some Rb- and Rb family (Rb, p107 and p130)-deficient differentiating neurons can proliferate and form tumors. Here, we found in mouse that differentiating cerebral cortical excitatory neurons underwent S-phase progression but not cell division after acute Rb family inactivation in differentiating neurons. However, the differentiating neurons underwent cell division and proliferated when Rb family members were inactivated in cortical progenitors. Differentiating neurons generated from Rb(-/-); p107(-/-); p130(-/-) (Rb-TKO) progenitors, but not acutely inactivated Rb-TKO differentiating neurons, activated the DNA double-strand break (DSB) repair pathway without increasing trimethylation at lysine 20 of histone H4 (H4K20), which has a role in protection against DNA damage. The activation of the DSB repair pathway was essential for the cell division of Rb-TKO differentiating neurons. These results suggest that newly born cortical neurons from progenitors become epigenetically protected from DNA damage and cell division in an Rb family-dependent manner.
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Affiliation(s)
- Mio Oshikawa
- Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
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25
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Retinal degeneration depends on Bmi1 function and reactivation of cell cycle proteins. Proc Natl Acad Sci U S A 2013; 110:E593-601. [PMID: 23359713 DOI: 10.1073/pnas.1108297110] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The epigenetic regulator Bmi1 controls proliferation in many organs. Reexpression of cell cycle proteins such as cyclin-dependent kinases (CDKs) is a hallmark of neuronal apoptosis in neurodegenerative diseases. Here we address the potential role of Bmi1 as a key regulator of cell cycle proteins during neuronal apoptosis. We show that several cell cycle proteins are expressed in different models of retinal degeneration and required in the Rd1 photoreceptor death process. Deleting E2f1, a downstream target of CDKs, provided temporary protection in Rd1 mice. Most importantly, genetic ablation of Bmi1 provided extensive photoreceptor survival and improvement of retinal function in Rd1 mice, mediated by a decrease in cell cycle markers and regulators independent of p16(Ink4a) and p19(Arf). These data reveal that Bmi1 controls the cell cycle-related death process, highlighting this pathway as a promising therapeutic target for neuroprotection in retinal dystrophies.
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26
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Sortilin participates in light-dependent photoreceptor degeneration in vivo. PLoS One 2012; 7:e36243. [PMID: 22558402 PMCID: PMC3338683 DOI: 10.1371/journal.pone.0036243] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 04/03/2012] [Indexed: 11/20/2022] Open
Abstract
Both proNGF and the neurotrophin receptor p75 (p75NTR) are known to regulate photoreceptor cell death caused by exposure of albino mice to intense illumination. ProNGF-induced apoptosis requires the participation of sortilin as a necessary p75NTR co-receptor, suggesting that sortilin may participate in the photoreceptor degeneration triggered by intense lighting. We report here that light-exposed albino mice showed sortilin, p75NTR, and proNGF expression in the outer nuclear layer, the retinal layer where photoreceptor cell bodies are located. In addition, cone progenitor-derived 661W cells subjected to intense illumination expressed sortilin and p75NTR and released proNGF into the culture medium. Pharmacological blockade of sortilin with either neurotensin or the “pro” domain of proNGF (pro-peptide) favored the survival of 661W cells subjected to intense light. In vivo, the pro-peptide attenuated retinal cell death in light-exposed albino mice. We propose that an auto/paracrine proapoptotic mechanism based on the interaction of proNGF with the receptor complex p75NTR/sortilin participates in intense light-dependent photoreceptor cell death. We therefore propose sortilin as a putative target for intervention in hereditary retinal dystrophies.
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27
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Aranda-Anzaldo A. The post-mitotic state in neurons correlates with a stable nuclear higher-order structure. Commun Integr Biol 2012; 5:134-9. [PMID: 22808316 PMCID: PMC3376047 DOI: 10.4161/cib.18761] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Neurons become terminally differentiated (TD) post-mitotic cells very early during development yet they may remain alive and functional for decades. TD neurons preserve the molecular machinery necessary for DNA synthesis that may be reactivated by different stimuli but they never complete a successful mitosis. The non-reversible nature of the post-mitotic state in neurons suggests a non-genetic basis for it since no set of mutations has been able to revert it. Comparative studies of the nuclear higher-order structure in neurons and cells with proliferating potential suggest that the non-reversible nature of the post-mitotic state in neurons has a structural basis in the stability of the nuclear higher-order structure.
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Affiliation(s)
- Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular; Facultad de Medicina; Universidad Autónoma del Estado de México; Toluca, México
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28
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Sachdeva UM, O'Brien JM. Understanding pRb: toward the necessary development of targeted treatments for retinoblastoma. J Clin Invest 2012; 122:425-34. [PMID: 22293180 DOI: 10.1172/jci57114] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Retinoblastoma is a pediatric retinal tumor initiated by biallelic inactivation of the retinoblastoma gene (RB1). RB1 was the first identified tumor suppressor gene and has defined roles in the regulation of cell cycle progression, DNA replication, and terminal differentiation. However, despite the abundance of work demonstrating the molecular function and identifying binding partners of pRb, the challenge facing molecular biologists and clinical oncologists is how to integrate this vast body of molecular knowledge into the development of targeted therapies for treatment of retinoblastoma. We propose that a more thorough genetic understanding of retinoblastoma would inform targeted treatment decisions and could improve outcomes and quality of life in children affected by this disease.
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Affiliation(s)
- Uma M Sachdeva
- Scheie Eye Institute, University of Pennsylvania, 51 N. 39th St., Philadelphia, Pennsylvania 19104, USA
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29
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Berta ÁI, Boesze-Battaglia K, Genini S, Goldstein O, O'Brien PJ, Szél Á, Acland GM, Beltran WA, Aguirre GD. Photoreceptor cell death, proliferation and formation of hybrid rod/S-cone photoreceptors in the degenerating STK38L mutant retina. PLoS One 2011; 6:e24074. [PMID: 21980341 PMCID: PMC3184085 DOI: 10.1371/journal.pone.0024074] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 08/02/2011] [Indexed: 11/19/2022] Open
Abstract
A homozygous mutation in STK38L in dogs impairs the late phase of photoreceptor development, and is followed by photoreceptor cell death (TUNEL) and proliferation (PCNA, PHH3) events that occur independently in different cells between 7-14 weeks of age. During this period, the outer nuclear layer (ONL) cell number is unchanged. The dividing cells are of photoreceptor origin, have rod opsin labeling, and do not label with markers specific for macrophages/microglia (CD18) or Müller cells (glutamine synthetase, PAX6). Nestin labeling is absent from the ONL although it labels the peripheral retina and ciliary marginal zone equally in normals and mutants. Cell proliferation is associated with increased cyclin A1 and LATS1 mRNA expression, but CRX protein expression is unchanged. Coincident with photoreceptor proliferation is a change in the photoreceptor population. Prior to cell death the photoreceptor mosaic is composed of L/M- and S-cones, and rods. After proliferation, both cone types remain, but the majority of rods are now hybrid photoreceptors that express rod opsin and, to a lesser extent, cone S-opsin, and lack NR2E3 expression. The hybrid photoreceptors renew their outer segments diffusely, a characteristic of cones. The results indicate the capacity for terminally differentiated, albeit mutant, photoreceptors to divide with mutations in this novel retinal degeneration gene.
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Affiliation(s)
- Ágnes I. Berta
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvanis, United States of America
- Department of Human Morphology and Developmental Biology, Semmelweis University of Medicine, Budapest, Hungary
| | - Kathleen Boesze-Battaglia
- School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sem Genini
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvanis, United States of America
| | - Orly Goldstein
- J.A. Baker Institute, College of Veterinary Medicine, Cornell University, Ithaca New York, United States of America
| | - Paul J. O'Brien
- Laboratory of Retinal Cell and Molecular Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ágoston Szél
- Department of Human Morphology and Developmental Biology, Semmelweis University of Medicine, Budapest, Hungary
| | - Gregory M. Acland
- J.A. Baker Institute, College of Veterinary Medicine, Cornell University, Ithaca New York, United States of America
| | - William A. Beltran
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvanis, United States of America
| | - Gustavo D. Aguirre
- School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvanis, United States of America
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Analysis of genes differentially expressed during retinal degeneration in three mouse models. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011. [PMID: 20237996 DOI: 10.1007/978-1-4419-1399-9_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
An estimated 100,000 people in the US alone have retinitis pigmentosa. This disease, caused by the loss of rods and cones, results in blindness. With the intention of identifying common cell death pathways that result in RP, the pattern of global gene expression in three different mouse models of retinal degeneration was analyzed using DNA arrays. The models used were opsin ( Delta255-256 ), a transgenic mouse line that expresses a mutant form of opsin with a deletion of an isoleucine at either position 255 or 256; the Bouse C mouse, whereby normal opsin is over-expressed by over 2 folds; MOT1, a model that expresses SV-40 T antigen downstream of opsin promoter and leads to retinal degeneration. We found that, at least in the 2 models of retinal degeneration that are characterized by rhodopsin abnormalities, death is due to the TNF pathway. In addition, there are a number of unknown genes not yet annotated in each of the models that could be promising in revealing novel functions in photoreceptors.
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Alva-Medina J, Maya-Mendoza A, Dent MAR, Aranda-Anzaldo A. Continued stabilization of the nuclear higher-order structure of post-mitotic neurons in vivo. PLoS One 2011; 6:e21360. [PMID: 21731716 PMCID: PMC3121788 DOI: 10.1371/journal.pone.0021360] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 05/26/2011] [Indexed: 11/19/2022] Open
Abstract
Background Cellular terminal differentiation (TD) correlates with a permanent exit from the cell cycle and so TD cells become stably post-mitotic. However, TD cells express the molecular machinery necessary for cell proliferation that can be reactivated by experimental manipulation, yet it has not been reported the stable proliferation of any type of reactivated TD cells. Neurons become post-mitotic after leaving the ventricular zone. When neurons are forced to reenter the cell cycle they invariably undergo cell death. Wider evidence indicates that the post-mitotic state cannot solely depend on gene products acting in trans, otherwise mutations in the corresponding genes may lead to reentry and completion of the cell cycle in TD cells, but this has not been observed. In the interphase, nuclear DNA of metazoan cells is organized in supercoiled loops anchored to a nuclear nuclear matrix (NM). The DNA-NM interactions define a higher-order structure in the cell nucleus (NHOS). We have previously compared the NHOS of aged rat hepatocytes with that of early post-mitotic rat neurons and our results indicated that a very stable NHOS is a common feature of both senescent and post-mitotic cells in vivo. Principal Findings In the present work we compared the NHOS in rat neurons from different post-natal ages. Our results show that the trend towards further stabilization of the NHOS in neurons continues throughout post-natal life. This phenomenon occurs in absence of overt changes in the post-mitotic state and transcriptional activity of neurons, suggesting that it is independent of functional constraints. Conclusions Apparently the continued stabilization of the NHOS as a function of time is basically determined by thermodynamic and structural constraints. We discuss how the resulting highly stable NHOS of neurons may be the structural, non-genetic basis of their permanent and irreversible post-mitotic state.
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Affiliation(s)
- Janeth Alva-Medina
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado de México, México
| | - Apolinar Maya-Mendoza
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado de México, México
| | - Myrna A. R. Dent
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado de México, México
| | - Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado de México, México
- * E-mail:
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32
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Baratchi S, Kanwar RK, Kanwar JR. Survivin: A target from brain cancer to neurodegenerative disease. Crit Rev Biochem Mol Biol 2010; 45:535-54. [DOI: 10.3109/10409238.2010.516740] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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33
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Abstract
Historically basic neuroscience research has made several important contributions to the cell biology of the nucleus, in particular the elucidation of nuclear structures and compartments. As research progressed towards elucidating the mechanism of neurological disease at the cellular and molecular levels, it is now providing insight into the importance and basis of coordination of nuclear pathways within the nucleus and with other cellular compartments. Ataxias, lethal neurodegenerative diseases that are distinguished by a progressive loss of motor coordination, stem from disruption of nuclear function.
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Affiliation(s)
- Harry T Orr
- Institute of Translational Neuroscience, Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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34
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Abstract
The complex neurodegeneration underlying Alzheimer disease (AD), although incompletely understood, is characterised by an aberrant re-entry into the cell cycle in neurons. Pathological evidence, in the form of cell cycle markers and regulatory proteins, suggests that cell cycle re-entry is an early event in AD, which precedes the formation of amyloid-beta plaques and neurofibrillary tangles (NFTs). Although the exact mechanisms that induce and mediate these cell cycle events in AD are not clear, significant advances have been made in further understanding the pathological role of cell cycle re-entry in AD. Importantly, recent studies indicate that cell cycle re-entry is not a consequence, but rather a cause, of neurodegeneration, suggesting that targeting of cell cycle re-entry may provide an opportunity for therapeutic intervention. Moreover, multiple inducers of cell cycle re-entry and their interactions in AD have been proposed. Here, we review the most recent advances in understanding the pathological implications of cell cycle re-entry in AD.
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35
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Casadesus G, Puig ER, Webber KM, Atwood CS, Escuer MC, Bowen RL, Perry G, Smith MA. Targeting gonadotropins: an alternative option for Alzheimer disease treatment. J Biomed Biotechnol 2010; 2006:39508. [PMID: 17047306 PMCID: PMC1559918 DOI: 10.1155/jbb/2006/39508] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Recent evidence indicates that, alongside oxidative stress, dysregulation of the cell cycle in neurons susceptible to degeneration in Alzheimer disease may play a crucial role in the initiation of the disease. As such, the role of reproductive hormones, which are closely associated with the cell cycle both during development and after birth, may be of key import. While estrogen has been the primary focus, the protective effects of hormone replacement therapy on cognition and dementia only during a “crucial period” led us to expand the study of hormonal influences to other members of the hypothalamic pituitary axis. Specifically, in this review, we focus on luteinizing hormone, which is not only increased in the sera of patients with Alzheimer disease but, like estrogen, is modulated by hormone replacement therapy and also influences cognitive behavior and pathogenic processing in animal models of the disease. Targeting gonadotropins may be a useful treatment strategy for disease targeting multiple pleiotropic downstream consequences.
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Affiliation(s)
- Gemma Casadesus
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Emma Ramiro Puig
- Departament de Fisiologia, Facultat de Farmacia, Universitat de Barcelona, Barcelona 08028, Spain
| | - Kate M. Webber
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Craig S. Atwood
- School of Medicine, University of Wisconsin and William S. Middleton Memorial Veterans Administration, Madison, WI 53705,
USA
| | - Margarida Castell Escuer
- Departament de Fisiologia, Facultat de Farmacia, Universitat de Barcelona, Barcelona 08028, Spain
| | | | - George Perry
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Mark A. Smith
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
- *Mark A. Smith:
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36
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Sulg M, Kirjavainen A, Pajusola K, Bueler H, Ylikoski J, Laiho M, Pirvola U. Differential sensitivity of the inner ear sensory cell populations to forced cell cycle re-entry and p53 induction. J Neurochem 2009; 112:1513-26. [PMID: 20050971 DOI: 10.1111/j.1471-4159.2009.06563.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Previous studies have shown that the maintenance of post-mitotic state is critical for the life-long survival of the inner ear mechanosensory cells, the hair cells. A general concept is that differentiated, post-mitotic cells rapidly die following cell cycle re-entry. Here we have compared the response of postnatal cochlear (auditory) and utricular (balance) hair cells to forced cell cycle reactivation and p53 up-regulation. Forced S-phase entry was triggered through the human papillomavirus-16 E7 oncogene misexpression in explant cultures. It induced DNA damage and p53 induction in cochlear outer hair cells and these cells were rapidly lost, before entry into mitosis. The death was attenuated by p53 inactivation. In contrast, despite DNA damage and p53 induction, utricular hair cells showed longer term survival and a proportion of them progressed into mitosis. Consistently, pharmacological elevation of p53 levels by nutlin-3a led to a death-prone phenotype of cochlear outer hair cells, while other hair cell populations were death-resistant. These data have important clinical implications as they show the importance of p53 in sensory cells that are essential in hearing function.
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Affiliation(s)
- Marilin Sulg
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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37
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Abstract
Aberrant cell cycle activity and DNA damage have been observed in neurons in association with various neurodegenerative conditions. While there is strong evidence for a causative role for these events in neurotoxicity, it is unclear how they are triggered and why they are toxic. Here, we introduce a brief background of the current view on cell cycle activity and DNA damage in neurons and speculate on their relevance to neuronal survival. Furthermore, we suggest that the two events may be triggered in common by deregulation of fundamental processes, such as chromatin modulation, which are required for maintaining both DNA integrity and proper regulation of cell cycle gene expression.
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Affiliation(s)
- Dohoon Kim
- Department of Brain and Cognitive Sciences, Howard Hughes Medical Institute, Cambridge, Massachusetts 01239, USA
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38
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Bajić VP, Spremo-Potparević B, Zivković L, Bonda DJ, Siedlak SL, Casadesus G, Lee HG, Smith MA. The X-chromosome instability phenotype in Alzheimer's disease: a clinical sign of accelerating aging? Med Hypotheses 2009; 73:917-20. [PMID: 19647374 DOI: 10.1016/j.mehy.2009.06.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 06/24/2009] [Indexed: 10/20/2022]
Abstract
Premature centromere division, or premature centromere separation (PCS), occurs when chromatid separation is dysfunctional, occurring earlier than usual during the interphase stage of mitosis. This phenomenon, seen in Robert's syndrome and various cancers, has also been documented in peripheral as well as neuronal cells of Alzheimer's disease (AD). In the latter instances, fluorescent in situ hybridization (FISH), applied to the centromere region of the X-chromosome in interphase nuclei of lymphocytes from peripheral blood in AD patients, demonstrated premature chromosomal separation before mitotic metaphase directly after completion of DNA replication in G(2) phase of the cell cycle. Furthermore, and perhaps unexpectedly given the presumptive post-mitotic status of terminally differentiated neurons, neurons in AD patients also showed significantly increased levels of PCS of the X-chromosome. Taken together with other phenomena such as cell cycle re-activation and ectopic re-expression of cyclins and cyclin dependent proteins, we propose that AD is an oncogenic phenotype leading to accelerated aging of the affected brain.
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Affiliation(s)
- Vladan P Bajić
- Institute of Biomedical Research, Galenika ad, 11000 Belgrade, Serbia.
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39
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Das G, Choi Y, Sicinski P, Levine EM. Cyclin D1 fine-tunes the neurogenic output of embryonic retinal progenitor cells. Neural Dev 2009; 4:15. [PMID: 19416500 PMCID: PMC2694796 DOI: 10.1186/1749-8104-4-15] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Accepted: 05/05/2009] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Maintaining the correct balance of proliferation versus differentiation in retinal progenitor cells (RPCs) is essential for proper development of the retina. The cell cycle regulator cyclin D1 is expressed in RPCs, and mice with a targeted null allele at the cyclin D1 locus (Ccnd1-/-) have microphthalmia and hypocellular retinas, the latter phenotype attributed to reduced RPC proliferation and increased photoreceptor cell death during the postnatal period. How cyclin D1 influences RPC behavior, especially during the embryonic period, is unclear. RESULTS In this study, we show that embryonic RPCs lacking cyclin D1 progress through the cell cycle at a slower rate and exit the cell cycle at a faster rate. Consistent with enhanced cell cycle exit, the relative proportions of cell types born in the embryonic period, such as retinal ganglion cells and photoreceptor cells, are increased. Unexpectedly, cyclin D1 deficiency decreases the proportions of other early born retinal neurons, namely horizontal cells and specific amacrine cell types. We also found that the laminar positioning of horizontal cells and other cell types is altered in the absence of cyclin D1. Genetically replacing cyclin D1 with cyclin D2 is not efficient at correcting the phenotypes due to the cyclin D1 deficiency, which suggests the D-cyclins are not fully redundant. Replacement with cyclin E or inactivation of cyclin-dependent kinase inhibitor p27Kip1 restores the balance of RPCs and retinal cell types to more normal distributions, which suggests that regulation of the retinoblastoma pathway is an important function for cyclin D1 during embryonic retinal development. CONCLUSION Our findings show that cyclin D1 has important roles in RPC cell cycle regulation and retinal histogenesis. The reduction in the RPC population due to a longer cell cycle time and to an enhanced rate of cell cycle exit are likely to be the primary factors driving retinal hypocellularity and altered output of precursor populations in the embryonic Ccnd1-/- retina.
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Affiliation(s)
- Gaurav Das
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA.
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40
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Cell Cycle Activation and CNS Injury. Neurotox Res 2009; 16:221-37. [PMID: 19526282 DOI: 10.1007/s12640-009-9050-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 03/26/2009] [Accepted: 03/26/2009] [Indexed: 12/28/2022]
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41
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Kim D, Frank CL, Dobbin MM, Tsunemoto RK, Tu W, Peng PL, Guan JS, Lee BH, Moy LY, Giusti P, Broodie N, Mazitschek R, Delalle I, Haggarty SJ, Neve RL, Lu Y, Tsai LH. Deregulation of HDAC1 by p25/Cdk5 in neurotoxicity. Neuron 2009; 60:803-17. [PMID: 19081376 DOI: 10.1016/j.neuron.2008.10.015] [Citation(s) in RCA: 221] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 09/02/2008] [Accepted: 10/09/2008] [Indexed: 12/19/2022]
Abstract
Aberrant cell-cycle activity and DNA damage are emerging as important pathological components in various neurodegenerative conditions. However, their underlying mechanisms are poorly understood. Here, we show that deregulation of histone deacetylase 1 (HDAC1) activity by p25/Cdk5 induces aberrant cell-cycle activity and double-strand DNA breaks leading to neurotoxicity. In a transgenic model for neurodegeneration, p25/Cdk5 activity elicited cell-cycle activity and double-strand DNA breaks that preceded neuronal death. Inhibition of HDAC1 activity by p25/Cdk5 was identified as an underlying mechanism for these events, and HDAC1 gain of function provided potent protection against DNA damage and neurotoxicity in cultured neurons and an in vivo model for ischemia. Our findings outline a pathological signaling pathway illustrating the importance of maintaining HDAC1 activity in the adult neuron. This pathway constitutes a molecular link between aberrant cell-cycle activity and DNA damage and is a potential target for therapeutics against diseases and conditions involving neuronal death.
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Affiliation(s)
- Dohoon Kim
- Howard Hughes Medical Institute, Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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42
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Fei XF, Qin ZH, Xiang B, Li LY, Han F, Fukunaga K, Liang ZQ. Olomoucine inhibits cathepsin L nuclear translocation, activates autophagy and attenuates toxicity of 6-hydroxydopamine. Brain Res 2009; 1264:85-97. [DOI: 10.1016/j.brainres.2009.01.057] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Revised: 01/19/2009] [Accepted: 01/21/2009] [Indexed: 01/11/2023]
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43
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Lee HG, Casadesus G, Nunomura A, Zhu X, Castellani RJ, Richardson SL, Perry G, Felsher DW, Petersen RB, Smith MA. The neuronal expression of MYC causes a neurodegenerative phenotype in a novel transgenic mouse. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:891-7. [PMID: 19164506 DOI: 10.2353/ajpath.2009.080583] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many different proteins associated with the cell cycle, including cyclins, cyclin-dependent kinases, and proto-oncogenes such as c-MYC (MYC), are increased in degenerating neurons. Consequently, an ectopic activation of the cell cycle machinery in neurons has emerged as a potential pathogenic mechanism of neuronal dysfunction and death in many neurodegenerative diseases, including Alzheimer's disease. However, the exact role of cell cycle re-entry during disease pathogenesis is unclear, primarily because of the lack of relevant research models to study the effects of cell cycle re-entry on mature neurons in vivo. To address this issue, we developed a new transgenic mouse model in which forebrain neurons (CaMKII-MYC) can be induced to enter the cell cycle using the physiologically relevant proto-oncogene MYC to drive cell cycle re-entry. We show that such cell cycle re-entry results in neuronal cell death, gliosis, and cognitive deficits. These findings provide compelling evidence that dysregulation of cell cycle re-entry results in neurodegeneration in vivo. Our current findings, coupled with those of previous reports, strengthen the hypothesis that neurodegeneration in Alzheimer's disease, similar to cellular proliferation in cancer, is a disease that results from inappropriate cell cycle control.
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Affiliation(s)
- Hyoung-gon Lee
- Department of Pathology, Case Western Reserve University, 2103 Cornell Rd., Cleveland, OH 44106, USA.
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44
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Cell cycle re-entry mediated neurodegeneration and its treatment role in the pathogenesis of Alzheimer's disease. Neurochem Int 2008; 54:84-8. [PMID: 19114068 DOI: 10.1016/j.neuint.2008.10.013] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 10/16/2008] [Accepted: 10/20/2008] [Indexed: 11/23/2022]
Abstract
As one of the earliest pathologic changes, the aberrant re-expression of many cell cycle-related proteins and inappropriate cell cycle control in specific vulnerable neuronal populations in Alzheimer's disease (AD) is emerging as an important component in the pathogenesis leading to AD and other neurodegenerative diseases. These events are clearly representative of a true cell cycle, rather than epiphenomena of other processes since, in AD and other neurodegenerative diseases, there is a true mitotic alteration that leads to DNA replication. While the exact role of cell cycle re-entry is unclear, recent studies using cell culture and animal models strongly support the notion that the dysregulation of cell cycle in neurons leads to the development of AD-related pathology such as hyperphosphorylation of tau and amyloid-beta deposition and ultimately causes neuronal cell death. Importantly, cell cycle re-entry is also evident in mutant amyloid-beta precursor protein and tau transgenic mice and, as in human disease, occurs prior to the development of the pathological hallmarks, neurofibrillary tangles and amyloid-beta plaques. Therefore, the study of aberrant cell cycle regulation in model systems, both cellular and animal, may provide extremely important insights into the pathogenesis of AD and also serve as a means to test novel therapeutic approaches.
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45
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Abstract
Neurons subject to degeneration in Alzheimer's disease (AD) exhibit evidence of re-entry into a mitotic cell cycle even before the development of substantial AD brain pathology. In efforts to identify the initiating factors underlying these cell cycle events (CCEs), we have characterized the appearance of the neuronal CCEs in the genomic-based R1.40 transgenic mouse model of AD. Notably, R1.40 mice exhibit neuronal CCEs in a reproducible temporal and spatial pattern that recapitulates the neuronal vulnerability seen in human AD. Neuronal CCEs first appear at 6 months in the frontal cortex layers II/III. This is 6-8 months before detectable amyloid beta (Abeta) deposition, suggesting that specific amyloid precursor protein (APP) processing products are responsible for the induction of neuronal CCEs. Furthermore, a reduction in the levels of Abeta (achieved by shifting the genetic background from C57BL/6 to the DBA/2 mouse strain) dramatically delays the appearance of neuronal CCEs. More significantly, elimination of beta-secretase activity blocks the appearance of CCEs, providing direct genetic evidence that the amyloidogenic processing of APP is required for the induction of CCEs. Finally, in vitro preparations of oligomeric, but not monomeric, Abeta induce DNA synthesis in dissociated cortical neurons, and this response is blocked by antioligomer specific antibodies. Together, our data suggest that low molecular weight aggregates of Abeta induce neuronal cell cycle re-entry in mouse models of Alzheimer's disease.
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46
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Zhang J, Herrup K. Cdk5 and the non-catalytic arrest of the neuronal cell cycle. Cell Cycle 2008; 7:3487-90. [PMID: 19001851 DOI: 10.4161/cc.7.22.7045] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Cyclin-dependent kinase 5 (Cdk5) is a nontraditional Cdk that is primarily active in postmitotic neurons. An important core function of Cdk5 involves regulating the migration and maturation of embryonic post-mitotic neurons. These developmental roles are dependent on its kinase activity. Initially, there was little evidence indicating a role for Cdk5 in normal cell cycle regulation. Recent data from our lab, however, suggest that Cdk5 plays a crucial role as a cell cycle suppressor in normal post-mitotic neurons and neuronal cell lines. It performs this foundation in a kinase independent manner. Cdk5 normally found in both nucleus and cytoplasm, but it exits the nucleus in neurons risk to death in an AD patient's brain. The shift in sub-cellular location is accompanied by cell cycle re-entry and neuronal death. This "new" function of Cdk5 raises cautions in the design of Cdk5-directed drugs for the therapy of neurodegenerative diseases.
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Affiliation(s)
- Jie Zhang
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854-8082, USA
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Rimkus SA, Katzenberger RJ, Trinh AT, Dodson GE, Tibbetts RS, Wassarman DA. Mutations in String/CDC25 inhibit cell cycle re-entry and neurodegeneration in a Drosophila model of Ataxia telangiectasia. Genes Dev 2008; 22:1205-20. [PMID: 18408079 DOI: 10.1101/gad.1639608] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutations in ATM (Ataxia telangiectasia mutated) result in Ataxia telangiectasia (A-T), a disorder characterized by progressive neurodegeneration. Despite advances in understanding how ATM signals cell cycle arrest, DNA repair, and apoptosis in response to DNA damage, it remains unclear why loss of ATM causes degeneration of post-mitotic neurons and why the neurological phenotype of ATM-null individuals varies in severity. To address these issues, we generated a Drosophila model of A-T. RNAi knockdown of ATM in the eye caused progressive degeneration of adult neurons in the absence of exogenously induced DNA damage. Heterozygous mutations in select genes modified the neurodegeneration phenotype, suggesting that genetic background underlies variable neurodegeneration in A-T. The neuroprotective activity of ATM may be negatively regulated by deacetylation since mutations in a protein deacetylase gene, RPD3, suppressed neurodegeneration, and a human homolog of RPD3, histone deacetylase 2, bound ATM and abrogated ATM activation in cell culture. Moreover, knockdown of ATM in post-mitotic neurons caused cell cycle re-entry, and heterozygous mutations in the cell cycle activator gene String/CDC25 inhibited cell cycle re-entry and neurodegeneration. Thus, we hypothesize that ATM performs a cell cycle checkpoint function to protect post-mitotic neurons from degeneration and that cell cycle re-entry causes neurodegeneration in A-T.
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Affiliation(s)
- Stacey A Rimkus
- Department of Biomolecular Chemistry, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
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48
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Abstract
Neurons are highly differentiated cells that normally never enter a cell cycle; if they do, the result is usually death, not division. For example, cerebellar granule neurons in staggerer and lurcher mutant mice initiate a cell cycle-like process just before they die. E2F1 is a transcription factor that promotes cell cycle progression. Because E2F1 is also involved in apoptosis, we bred double mutants (E2f1-/-; staggerer and E2f1-/-; lurcher) to assess its role in the cell cycle-related death of cerebellar granule cells in vivo. We found neither granule cell cycle initiation nor cell death was significantly altered in either double mutant. However, after postnatal day 10, neurons throughout the CNS of E2f1-/- and E2f1+/- animals were found to express cell cycle proteins and replicate their DNA. Whereas Map2 and synapsin1 staining are little altered, there is a reduction of calbindin in Purkinje cell dendrites at 1 year of age, suggesting that the mutant cells also undergo a slow, subtle atrophy. These events are cell autonomous, because cultured E2f1-/- cortical neurons "cycle" in vitro, whereas wild-type neurons do not. Our results suggest that, in mature CNS neurons, E2F1 functions as a cell cycle suppressor.
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49
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Herrup K, Yang Y. Cell cycle regulation in the postmitotic neuron: oxymoron or new biology? Nat Rev Neurosci 2007; 8:368-78. [PMID: 17453017 DOI: 10.1038/nrn2124] [Citation(s) in RCA: 365] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adult CNS neurons are typically described as permanently postmitotic but there is probably nothing permanent about the neuronal cell cycle arrest. Rather, it appears that these highly differentiated cells must constantly keep their cell cycle in check. Relaxation of this vigilance leads to the initiation of a cell cycle and entrance into an altered and vulnerable state, often leading to death. There is evidence that neurons which are at risk of neurodegeneration are also at risk of re-initiating a cell cycle process that involves the expression of cell cycle proteins and DNA replication. Failure of cell cycle regulation might be a root cause of several neurodegenerative disorders and a final common pathway for others.
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Affiliation(s)
- Karl Herrup
- Department of Cell Biology and Neuroscience, Rutgers University, 604 Allison Road, Piscataway, New Jersey 08854, USA.
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McShea A, Lee HG, Petersen RB, Casadesus G, Vincent I, Linford NJ, Funk JO, Shapiro RA, Smith MA. Neuronal cell cycle re-entry mediates Alzheimer disease-type changes. Biochim Biophys Acta Mol Basis Dis 2007; 1772:467-72. [PMID: 17095196 DOI: 10.1016/j.bbadis.2006.09.010] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 09/26/2006] [Accepted: 09/27/2006] [Indexed: 11/20/2022]
Abstract
Evidence showing the ectopic re-expression of cell cycle-related proteins in specific vulnerable neuronal populations in Alzheimer disease led us to formulate the hypothesis that neurodegeneration, like cancer, is a disease of inappropriate cell cycle control. To test this notion, we used adenoviral-mediated expression of c-myc and ras oncogenes to drive postmitotic primary cortical neurons into the cell cycle. Cell cycle re-entry in neurons was associated with increased DNA content, as determined using BrdU and DAPI, and the re-expression of cyclin B1, a marker for the G2/M phase of the cell cycle. Importantly, we also found that cell cycle re-entry in primary neurons leads to tau phosphorylation and conformational changes similar to that seen in Alzheimer disease. This study establishes that the cell cycle can be instigated in normally quiescent neuronal cells and results in a phenotype that shares features of degenerative neurons in Alzheimer disease. As such, our neuronal cell model may be extremely valuable for the development of novel therapeutic strategies.
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Affiliation(s)
- Andrew McShea
- Department of Biology, CombiMatrix Corp, Mukilteo, WA 98275, USA
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