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Wodrich APK, Harris BT, Giniger E. Changes in mitochondrial distribution occur at the axon initial segment in association with neurodegeneration in Drosophila. Biol Open 2024; 13:bio060335. [PMID: 38912559 PMCID: PMC11261633 DOI: 10.1242/bio.060335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/17/2024] [Indexed: 06/25/2024] Open
Abstract
Changes in mitochondrial distribution are a feature of numerous age-related neurodegenerative diseases. In Drosophila, reducing the activity of Cdk5 causes a neurodegenerative phenotype and is known to affect several mitochondrial properties. Therefore, we investigated whether alterations of mitochondrial distribution are involved in Cdk5-associated neurodegeneration. We find that reducing Cdk5 activity does not alter the balance of mitochondrial localization to the somatodendritic versus axonal neuronal compartments of the mushroom body, the learning and memory center of the Drosophila brain. We do, however, observe changes in mitochondrial distribution at the axon initial segment (AIS), a neuronal compartment located in the proximal axon involved in neuronal polarization and action potential initiation. Specifically, we observe that mitochondria are partially excluded from the AIS in wild-type neurons, but that this exclusion is lost upon reduction of Cdk5 activity, concomitant with the shrinkage of the AIS domain that is known to occur in this condition. This mitochondrial redistribution into the AIS is not likely due to the shortening of the AIS domain itself but rather due to altered Cdk5 activity. Furthermore, mitochondrial redistribution into the AIS is unlikely to be an early driver of neurodegeneration in the context of reduced Cdk5 activity.
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Affiliation(s)
- Andrew P. K. Wodrich
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC 20007, USA
- College of Medicine, University of Kentucky, Lexington, KY 40506, USA
| | - Brent T. Harris
- Department of Pathology, Georgetown University, Washington, DC 20007, USA
- Department of Neurology, Georgetown University, Washington, DC 20007, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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2
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Wodrich APK, Harris BT, Giniger E. MANIPULATING MITOCHONDRIAL REACTIVE OXYGEN SPECIES ALTERS SURVIVAL IN UNEXPECTED WAYS IN A DROSOPHILA MODEL OF NEURODEGENERATION. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.25.586603. [PMID: 38585927 PMCID: PMC10996551 DOI: 10.1101/2024.03.25.586603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Reactive oxygen species (ROS) are associated with aging and neurodegeneration, but the significance of this association remains obscure. Here, using a Drosophila model of age-related neurodegeneration, we probe this relationship in the pathologically relevant tissue, the brain, by quantifying three specific mitochondrial ROS and manipulating these redox species pharmacologically. Our goal is to ask whether pathology-associated changes in redox state are detrimental for survival, whether they may be beneficial responses, or whether they are simply covariates of pathology that do not alter viability. We find, surprisingly, that increasing mitochondrial H2O2 correlates with improved survival. We also find evidence that drugs that alter the mitochondrial glutathione redox potential modulate survival primarily through the compensatory effects they induce rather than through their direct effects on the final mitochondrial glutathione redox potential per se. We also find that the response to treatment with a redox-altering drug varies dramatically depending on the age at which the drug is administered, the duration of the treatment, and the genotype of the individual receiving the drug. These data have important implications for the design and interpretation of studies investigating the effect of redox state on health and disease as well as on efforts to modify the redox state to achieve therapeutic goals.
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Affiliation(s)
- Andrew P. K. Wodrich
- National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bethesda, MD
- Georgetown University, Interdisciplinary Program in Neuroscience, Washington, DC
- University of Kentucky, College of Medicine, Lexington, KY
| | - Brent T. Harris
- Georgetown University, Interdisciplinary Program in Neuroscience, Washington, DC
- Georgetown University, Department of Pathology, Washington, DC
- Georgetown University, Department of Neurology, Washington, DC
| | - Edward Giniger
- National Institutes of Health, National Institute of Neurological Disorders and Stroke, Bethesda, MD
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3
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Wodrich APK, Harris BT, Giniger E. Changes in mitochondrial distribution occur at the axon initial segment in association with neurodegeneration in Drosophila. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580288. [PMID: 38405730 PMCID: PMC10888798 DOI: 10.1101/2024.02.14.580288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Changes in mitochondrial distribution are a feature of numerous age-related neurodegenerative diseases. In Drosophila, reducing the activity of Cdk5 causes a neurodegenerative phenotype and is known to affect several mitochondrial properties. Therefore, we investigated whether alterations of mitochondrial distribution are involved in Cdk5-associated neurodegeneration. We find that reducing Cdk5 activity does not alter the balance of mitochondrial localization to the somatodendritic vs. axonal neuronal compartments of the mushroom body, the learning and memory center of the Drosophila brain. We do, however, observe changes in mitochondrial distribution at the axon initial segment (AIS), a neuronal compartment located in the proximal axon involved in neuronal polarization and action potential initiation. Specifically, we observe that mitochondria are partially excluded from the AIS in wild-type neurons, but that this exclusion is lost upon reduction of Cdk5 activity, concomitant with the shrinkage of the AIS domain that is known to occur in this condition. This mitochondrial redistribution into the AIS is not likely due to the shortening of the AIS domain itself but rather due to altered Cdk5 activity. Furthermore, mitochondrial redistribution into the AIS is unlikely to be an early driver of neurodegeneration in the context of reduced Cdk5 activity.
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Affiliation(s)
- Andrew P. K. Wodrich
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC
- College of Medicine, University of Kentucky, Lexington, KY
| | - Brent T. Harris
- Department of Pathology, Georgetown University, Washington, DC
- Department of Neurology, Georgetown University, Washington, DC
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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Natural Products in Therapeutic Management of Multineurodegenerative Disorders by Targeting Autophagy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:6347792. [PMID: 34557265 PMCID: PMC8455192 DOI: 10.1155/2021/6347792] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/09/2021] [Accepted: 08/18/2021] [Indexed: 12/16/2022]
Abstract
Autophagy is an essential cellular process that involves the transport of cytoplasmic content in double-membraned vesicles to lysosomes for degradation. Neurons do not undergo cytokinesis, and thus, the cell division process cannot reduce levels of unnecessary proteins. The primary cause of neurodegenerative disorders (NDs) is the abnormal deposition of proteins inside neuronal cells, and this could be averted by autophagic degradation. Thus, autophagy is an important consideration when considering means of developing treatments for NDs. Various pharmacological studies have reported that the active components in herbal medicines exhibit therapeutic benefits in NDs, for example, by inhibiting cholinesterase activity and modulating amyloid beta levels, and α-synuclein metabolism. A variety of bioactive constituents from medicinal plants are viewed as promising autophagy controllers and are revealed to recover the NDs by targeting the autophagic pathway. In the present review, we discuss the role of autophagy in the therapeutic management of several NDs. The molecular process responsible for autophagy and its importance in various NDs and the beneficial effects of medicinal plants in NDs by targeting autophagy are also discussed.
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Hyperactive Innate Immunity Causes Degeneration of Dopamine Neurons upon Altering Activity of Cdk5. Cell Rep 2020; 26:131-144.e4. [PMID: 30605670 PMCID: PMC6442473 DOI: 10.1016/j.celrep.2018.12.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 10/10/2018] [Accepted: 12/05/2018] [Indexed: 11/23/2022] Open
Abstract
Innate immunity is central to the pathophysiology of neurodegenerative disorders, but it remains unclear why immunity is altered in the disease state and whether changes in immunity are a cause or a consequence of neuronal dysfunction. Here, we identify a molecular pathway that links innate immunity to age-dependent loss of dopaminergic neurons in Drosophila. We find, first, that altering the expression of the activating subunit of the Cdk5 protein kinase (Cdk5α) causes severe disruption of autophagy. Second, this disruption of autophagy is both necessary and sufficient to cause the hyperactivation of innate immunity, particularly expression of anti-microbial peptides. Finally, it is the upregulation of immunity that induces the age-dependent death of dopaminergic neurons. Given the dysregulation of Cdk5 and innate immunity in human neurodegeneration and the conserved role of the kinase in the regulation of autophagy, this sequence is likely to have direct application to the chain of events in human neurodegenerative disease. How can one disentangle the many pathologies of neurodegeneration from one another and from normal aging? Shukla et al. show that a mutation in Drosophila kills neurons by impairing autophagy, which in turn stimulates neurotoxic levels of innate immunity, and this acts synergistically with a parallel pathway that accelerates aging.
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Spurrier J, Shukla AK, Buckley T, Smith-Trunova S, Kuzina I, Gu Q, Giniger E. Expression of a Fragment of Ankyrin 2 Disrupts the Structure of the Axon Initial Segment and Causes Axonal Degeneration in Drosophila. Mol Neurobiol 2019; 56:5689-5700. [PMID: 30666562 PMCID: PMC6616013 DOI: 10.1007/s12035-019-1477-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 01/10/2019] [Indexed: 11/26/2022]
Abstract
Neurodegenerative stimuli are often associated with perturbation of the axon initial segment (AIS), but it remains unclear whether AIS disruption is causative for neurodegeneration or is a downstream step in disease progression. Here, we demonstrate that either of two separate, genetically parallel pathways that disrupt the AIS induce axonal degeneration and loss of neurons in the central brain of Drosophila. Expression of a portion of the C-terminal tail of the Ank2-L isoform of Ankyrin severely shortens the AIS in Drosophila mushroom body (MB) neurons, and this shortening occurs through a mechanism that is genetically separate from the previously described Cdk5α-dependent pathway of AIS regulation. Further, either manipulation triggers morphological degeneration of MB axons and is accompanied by neuron loss. Taken together, our results are consistent with the hypothesis that disruption of the AIS is causally related to degeneration of fly central brain neurons, and we suggest that similar mechanisms may contribute to neurodegeneration in mammals.
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Affiliation(s)
- Joshua Spurrier
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
- Cellular Neuroscience, Neurodegeneration and Repair Program, Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Arvind K Shukla
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
| | - Tyler Buckley
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
- The Scripps Research Institute, San Diego, CA, USA
| | - Svetlana Smith-Trunova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
- Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Irina Kuzina
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
| | - Qun Gu
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bldg. 35, Rm 1C-1002, 35 Convent Dr., Bethesda, MD, 20892, USA.
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CDK5-mediated phosphorylation of CP190 may regulate locomotor activity in adult female Drosophila. J Genet Genomics 2018; 45:177-181. [PMID: 29571672 DOI: 10.1016/j.jgg.2017.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 08/26/2017] [Accepted: 09/15/2017] [Indexed: 11/21/2022]
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8
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Spurrier J, Shukla AK, McLinden K, Johnson K, Giniger E. Altered expression of the Cdk5 activator-like protein, Cdk5α, causes neurodegeneration, in part by accelerating the rate of aging. Dis Model Mech 2018; 11:dmm031161. [PMID: 29469033 PMCID: PMC5897722 DOI: 10.1242/dmm.031161] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 02/02/2018] [Indexed: 12/11/2022] Open
Abstract
Aging is the greatest risk factor for neurodegeneration, but the connection between the two processes remains opaque. This is in part for want of a rigorous way to define physiological age, as opposed to chronological age. Here, we develop a comprehensive metric for physiological age in Drosophila, based on genome-wide expression profiling. We applied this metric to a model of adult-onset neurodegeneration, increased or decreased expression of the activating subunit of the Cdk5 protein kinase, encoded by the gene Cdk5α, the ortholog of mammalian p35. Cdk5α-mediated degeneration was associated with a 27-150% acceleration of the intrinsic rate of aging, depending on the tissue and genetic manipulation. Gene ontology analysis and direct experimental tests revealed that affected age-associated processes included numerous core phenotypes of neurodegeneration, including enhanced oxidative stress and impaired proteostasis. Taken together, our results suggest that Cdk5α-mediated neurodegeneration results from accelerated aging, in combination with cell-autonomous neuronal insults. These data fundamentally recast our picture of the relationship between neurodegeneration and its most prominent risk factor, natural aging.
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Affiliation(s)
- Joshua Spurrier
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 02892, USA
- The Johns Hopkins University/National Institutes of Health Graduate Partnership Program, National Institutes of Health, Bethesda, MD 02892, USA
| | - Arvind Kumar Shukla
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 02892, USA
| | - Kristina McLinden
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 02892, USA
| | - Kory Johnson
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 02892, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 02892, USA
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9
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Zhao G, Wang C, Wang H, Gao L, Liu Z, Xu B, Guo X. Characterization of the CDK5 gene in Apis cerana cerana (AccCDK5) and a preliminary identification of its activator gene, AccCDK5r1. Cell Stress Chaperones 2018; 23:13-28. [PMID: 28674940 PMCID: PMC5741578 DOI: 10.1007/s12192-017-0820-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 06/01/2017] [Accepted: 06/07/2017] [Indexed: 12/12/2022] Open
Abstract
Cyclin-dependent kinase 5 (CDK5) is an unusual CDK whose function has been implicated in protecting the central nervous system (CNS) from oxidative damage. However, there have been few studies of CDK5 in insects. In this study, we identified the AccCDK5 gene from Apis cerana cerana and investigated its role in oxidation resistance. We found that AccCDK5 is highly conserved across species and contains conserved features of the CDK5 family. The results of qPCR analysis indicated that AccCDK5 is highly expressed during the larval and pupal stages and in the adult head and muscle. We further observed that AccCDK5 is induced by several environmental oxidative stresses. Moreover, the overexpression of the AccCDK5 protein in E. coli enhances the resistance of the bacteria to oxidative stress. The activation of CDK5 requires binding to its activator. Therefore, we also identified and cloned cyclin-dependent kinase 5 regulatory subunit 1, which we named AccCDK5r1, from Apis cerana cerana. AccCDK5r1 contains a conserved cell localization targeting domain as well as binding and activation sites for CDK5. Yeast two-hybrid analysis demonstrated the interaction between AccCDK5 and AccCDK5r1. The expression patterns of the two genes were similar after stress treatment. Collectively, these results suggest that AccCDK5 plays a pivotal role in the response to oxidative stresses and that AccCDK5r1 is a potential activator of AccCDK5.
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Affiliation(s)
- Guangdong Zhao
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Chen Wang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Hongfang Wang
- College of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Lijun Gao
- College of Life Sciences, Taishan Medical University, Taian, Shandong, 271016, People's Republic of China
| | - Zhenguo Liu
- College of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China
| | - Baohua Xu
- College of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.
| | - Xingqi Guo
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.
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10
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Nandi N, Tyra LK, Stenesen D, Krämer H. Stress-induced Cdk5 activity enhances cytoprotective basal autophagy in Drosophila melanogaster by phosphorylating acinus at serine 437. eLife 2017; 6:e30760. [PMID: 29227247 PMCID: PMC5760206 DOI: 10.7554/elife.30760] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/08/2017] [Indexed: 12/22/2022] Open
Abstract
Cdk5 is a post-mitotic kinase with complex roles in maintaining neuronal health. The various mechanisms by which Cdk5 inhibits and promotes neurodegeneration are still poorly understood. Here, we show that in Drosophila melanogaster Cdk5 regulates basal autophagy, a key mechanism suppressing neurodegeneration. In a targeted screen, Cdk5 genetically interacted with Acinus (Acn), a primarily nuclear protein, which promotes starvation-independent, basal autophagy. Loss of Cdk5, or its required cofactor p35, reduces S437-Acn phosphorylation, whereas Cdk5 gain-of-function increases pS437-Acn levels. The phospho-mimetic S437D mutation stabilizes Acn and promotes basal autophagy. In p35 mutants, basal autophagy and lifespan are reduced, but restored to near wild-type levels in the presence of stabilized AcnS437D. Expression of aggregation-prone polyQ-containing proteins or the Amyloid-β42 peptide, but not alpha-Synuclein, enhances Cdk5-dependent phosphorylation of S437-Acn. Our data indicate that Cdk5 is required to maintain the protective role of basal autophagy in the initial responses to a subset of neurodegenerative challenges.
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Affiliation(s)
- Nilay Nandi
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Lauren K Tyra
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Drew Stenesen
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Helmut Krämer
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
- Department of Cell BiologyUT Southwestern Medical CenterDallasUnited States
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11
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Delayed glial clearance of degenerating axons in aged Drosophila is due to reduced PI3K/Draper activity. Nat Commun 2016; 7:12871. [PMID: 27647497 PMCID: PMC5034330 DOI: 10.1038/ncomms12871] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 08/10/2016] [Indexed: 01/09/2023] Open
Abstract
Advanced age is the greatest risk factor for neurodegenerative disorders, but the mechanisms that render the senescent brain vulnerable to disease are unclear. Glial immune responses provide neuroprotection in a variety of contexts. Thus, we explored how glial responses to neurodegeneration are altered with age. Here we show that glia–axon phagocytic interactions change dramatically in the aged Drosophila brain. Aged glia clear degenerating axons slowly due to low phosphoinositide-3-kinase (PI3K) signalling and, subsequently, reduced expression of the conserved phagocytic receptor Draper/MEGF10. Importantly, boosting PI3K/Draper activity in aged glia significantly reverses slow phagocytic responses. Moreover, several hours post axotomy, early hallmarks of Wallerian degeneration (WD) are delayed in aged flies. We propose that slow clearance of degenerating axons is mechanistically twofold, resulting from deferred initiation of axonal WD and reduced PI3K/Draper-dependent glial phagocytic function. Interventions that boost glial engulfment activity, however, can substantially reverse delayed clearance of damaged neuronal debris. Glial engulfment declines with age, but the mechanism is unclear. Here authors show that in the Drosophila olfactory system, glial phagocytosis of injury-induced degenerating axons decreases with age due to reduced PI3K/Draper activity, and restoring Draper in aged glia rescues such defects.
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12
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Knockdown of Expression of Cdk5 or p35 (a Cdk5 Activator) Results in Podocyte Apoptosis. PLoS One 2016; 11:e0160252. [PMID: 27479491 PMCID: PMC4968817 DOI: 10.1371/journal.pone.0160252] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 07/15/2016] [Indexed: 11/25/2022] Open
Abstract
Podocytes are terminally differentiated glomerular epithelial cells. Podocyte loss has been found in many renal diseases. Cdk5 is a cyclin-dependent protein kinase which is predominantly regulated by p35. To study the role of Cdk5/p35 in podocyte survival, we first applied western blotting (WB) analysis to confirm the time-course expression of Cdk5 and p35 during kidney development and in cultured immortalized mouse podocytes. We also demonstrated that p35 plays an important role in promoting podocyte differentiation by overexpression of p35 in podocytes. To deregulate the expression of Cdk5 or p35 in mouse podocytes, we used RNAi and analyzed cell function and apoptosis assaying for podocyte specific marker Wilms Tumor 1 (WT1) and cleaved caspase 3, respectively. We also counted viable cells using cell counting kit-8. We found that depletion of Cdk5 causes decreased expression of WT1 and apoptosis. It is noteworthy, however, that downregulation of p35 reduced Cdk5 activity, but had no effect on cleaved caspase 3 expression. It did, however, reduce expression of WT1, a transcription factor, and produced podocyte dysmorphism. On the other hand increased apoptosis could be detected in p35-deregulated podocytes using the TUNEL analysis and immunofluorescent staining with cleaved caspase3 antibody. Viability of podocytes was decreased in both Cdk5 and p35 knockdown cells. Knocking down Cdk5 or p35 gene by RNAi does not affect the cycline I expression, another Cdk5 activator in podocyes. We conclude that Cdk5 and p35 play a crucial role in maintaining podocyte differentiation and survival, and suggest these proteins as targets for therapeutic intervention in podocyte-damaged kidney diseases.
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13
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Nitric oxide mediates glial-induced neurodegeneration in Alexander disease. Nat Commun 2015; 6:8966. [PMID: 26608817 PMCID: PMC4674772 DOI: 10.1038/ncomms9966] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 10/22/2015] [Indexed: 01/07/2023] Open
Abstract
Glia play critical roles in maintaining the structure and function of the nervous system; however, the specific contribution that astroglia make to neurodegeneration in human disease states remains largely undefined. Here we use Alexander disease, a serious degenerative neurological disorder caused by astrocyte dysfunction, to identify glial-derived NO as a signalling molecule triggering astrocyte-mediated neuronal degeneration. We further find that NO acts through cGMP signalling in neurons to promote cell death. Glial cells themselves also degenerate, via the DNA damage response and p53. Our findings thus define a specific mechanism for glial-induced non-cell autonomous neuronal cell death, and identify a potential therapeutic target for reducing cellular toxicity in Alexander disease, and possibly other neurodegenerative disorders with glial dysfunction. Alexander disease is a rare neurological disorder caused by mutations in GFAP, yet it is unclear how glial disruptions lead to neural death. Here, Wang et al. identify a mechanism by which glial-derived nitric oxide leads to neuronal degeneration in fly and mouse models of the disease.
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14
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Smith-Trunova S, Prithviraj R, Spurrier J, Kuzina I, Gu Q, Giniger E. Cdk5 regulates developmental remodeling of mushroom body neurons in Drosophila. Dev Dyn 2015; 244:1550-63. [PMID: 26394609 DOI: 10.1002/dvdy.24350] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 09/10/2015] [Accepted: 09/19/2015] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND During metamorphosis, axons and dendrites of the mushroom body (MB) in the Drosophila central brain are remodeled extensively to support the transition from larval to adult behaviors. RESULTS We show here that the neuronal cyclin-dependent kinase, Cdk5, regulates the timing and rate of mushroom body remodeling: reduced Cdk5 activity causes a delay in pruning of MB neurites, while hyperactivation accelerates it. We further show that Cdk5 cooperates with the ubiquitin-proteasome system in this process. Finally, we show that Cdk5 modulates the first overt step in neurite disassembly, dissolution of the neuronal tubulin cytoskeleton, and provide evidence that it also acts at additional steps of MB pruning. CONCLUSIONS These data show that Cdk5 regulates the onset and extent of remodeling of the Drosophila MB. Given the wide phylogenetic conservation of Cdk5, we suggest that it is likely to play a role in developmental remodeling in other systems, as well. Moreover, we speculate that the well-established role of Cdk5 in neurodegeneration may involve some of the same cellular mechanisms that it uses during developmental remodeling.
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Affiliation(s)
- Svetlana Smith-Trunova
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Ranjini Prithviraj
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Joshua Spurrier
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland.,The Johns Hopkins University/National Institutes of Health Graduate Partnership Program, National Institutes of Health, Bethesda, Maryland
| | - Irina Kuzina
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Qun Gu
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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15
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Posada-Duque RA, López-Tobón A, Piedrahita D, González-Billault C, Cardona-Gomez GP. p35 and Rac1 underlie the neuroprotection and cognitive improvement induced by CDK5 silencing. J Neurochem 2015; 134:354-70. [PMID: 25864429 DOI: 10.1111/jnc.13127] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 04/01/2015] [Accepted: 04/09/2015] [Indexed: 01/27/2023]
Abstract
CDK5 plays an important role in neurotransmission and synaptic plasticity in the normal function of the adult brain, and dysregulation can lead to Tau hyperphosphorylation and cognitive impairment. In a previous study, we demonstrated that RNAi knock down of CDK5 reduced the formation of neurofibrillary tangles (NFT) and prevented neuronal loss in triple transgenic Alzheimer's mice. Here, we report that CDK5 RNAi protected against glutamate-mediated excitotoxicity using primary hippocampal neurons transduced with adeno-associated virus 2.5 viral vector eGFP-tagged scrambled or CDK5 shRNA-miR during 12 days. Protection was dependent on a concomitant increase in p35 and was reversed using p35 RNAi, which affected the down-stream Rho GTPase activity. Furthermore, p35 over-expression and constitutively active Rac1 mimicked CDK5 silencing-induced neuroprotection. In addition, 3xTg-Alzheimer's disease mice (24 months old) were injected in the hippocampus with scrambled or CDK5 shRNA-miR, and spatial learning and memory were performed 3 weeks post-injection using 'Morris' water maze test. Our data showed that CDK5 knock down induced an increase in p35 protein levels and Rac activity in triple transgenic Alzheimer's mice, which correlated with the recovery of cognitive function; these findings confirm that increased p35 and active Rac are involved in neuroprotection. In summary, our data suggest that p35 acts as a mediator of Rho GTPase activity and contributes to the neuroprotection induced by CDK5 RNAi.
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Affiliation(s)
- Rafael Andres Posada-Duque
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, Faculty of Medicine, SIU, Calle 70 N°. 52-21, University of Antioquia UdeA, Medellín, Colombia
| | - Alejandro López-Tobón
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, Faculty of Medicine, SIU, Calle 70 N°. 52-21, University of Antioquia UdeA, Medellín, Colombia
| | - Diego Piedrahita
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, Faculty of Medicine, SIU, Calle 70 N°. 52-21, University of Antioquia UdeA, Medellín, Colombia
| | - Christian González-Billault
- Department of Biology, Faculty of Sciences, Laboratory of Cell and Neuronal Dynamics, Universidad de Chile, Ñuñoa, Santiago, Chile
| | - Gloria Patricia Cardona-Gomez
- Cellular and Molecular Neurobiology Area, Group of Neuroscience of Antioquia, Faculty of Medicine, SIU, Calle 70 N°. 52-21, University of Antioquia UdeA, Medellín, Colombia
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16
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Gkikas I, Petratou D, Tavernarakis N. Longevity pathways and memory aging. Front Genet 2014; 5:155. [PMID: 24926313 PMCID: PMC4044971 DOI: 10.3389/fgene.2014.00155] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 05/10/2014] [Indexed: 12/28/2022] Open
Abstract
The aging process has been associated with numerous pathologies at the cellular, tissue, and organ level. Decline or loss of brain functions, including learning and memory, is one of the most devastating and feared aspects of aging. Learning and memory are fundamental processes by which animals adjust to environmental changes, evaluate various sensory signals based on context and experience, and make decisions to generate adaptive behaviors. Age-related memory impairment is an important phenotype of brain aging. Understanding the molecular mechanisms underlying age-related memory impairment is crucial for the development of therapeutic strategies that may eventually lead to the development of drugs to combat memory loss. Studies in invertebrate animal models have taught us much about the physiology of aging and its effects on learning and memory. In this review we survey recent progress relevant to conserved molecular pathways implicated in both aging and memory formation and consolidation.
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Affiliation(s)
- Ilias Gkikas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion Crete, Greece
| | - Dionysia Petratou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion Crete, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion Crete, Greece ; Department of Basic Sciences, Faculty of Medicine, University of Crete, Heraklion Crete, Greece
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17
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Li X, Yang Z, Zeng Y, Xu H, Li H, Han Y, Long X, You C. Cell cycle-related genes p57kip2, Cdk5 and Spin in the pathogenesis of neural tube defects. Neural Regen Res 2013; 8:1863-71. [PMID: 25206495 PMCID: PMC4145975 DOI: 10.3969/j.issn.1673-5374.2013.20.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/19/2013] [Indexed: 02/05/2023] Open
Abstract
In the field of developmental neurobiology, accurate and ordered regulation of the cell cycle and apoptosis are crucial factors contributing to the normal formation of the neural tube. Preliminary studies identified several genes involved in the development of neural tube defects. In this study, we established a model of developmental neural tube defects by administration of retinoic acid to pregnant rats. Gene chip hybridization analysis showed that genes related to the cell cycle and apoptosis, signal transduction, transcription and translation regulation, energy and metabolism, heat shock, and matrix and cytoskeletal proteins were all involved in the formation of developmental neural tube defects. Among these, cell cycle-related genes were predominant. Retinoic acid ment caused differential expression of three cell cycle-related genes p57kip2, Cdk5 and Spin, the expression levels of which were downregulated by retinoic acid and upregulated during normal neural tube formation. The results of this study indicate that cell cycle-related genes play an important role in the formation of neural tube defects. P57kip2, Cdk5 and Spin may be critical genes in the pathogenesis of neural tube defects.
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Affiliation(s)
- Xinjun Li
- Department of Neurosurgery, Deyang People's Hospital, Deyang 618000, Sichuan Province, China
| | - Zhong Yang
- Department of Neurobiology, the Third Military Medical University of Chinese PLA, Chongqing 400038, China
| | - Yi Zeng
- Department of Neurosurgery, Sichuan Provincial People's Hospital, Chengdu 610041, Sichuan Province, China
| | - Hong Xu
- Department of Neurosurgery, Deyang People's Hospital, Deyang 618000, Sichuan Province, China
| | - Hongli Li
- Department of Neurobiology, the Third Military Medical University of Chinese PLA, Chongqing 400038, China
| | - Yangyun Han
- Department of Neurosurgery, Deyang People's Hospital, Deyang 618000, Sichuan Province, China
| | - Xiaodong Long
- Department of Neurosurgery, Deyang People's Hospital, Deyang 618000, Sichuan Province, China
| | - Chao You
- Department of Neurosurgery, West China Hospital of Sichuan University, Chengdu 610041, Sichuan Province, China
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18
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Chen BR, Li Y, Eisenstatt JR, Runge KW. Identification of a lifespan extending mutation in the Schizosaccharomyces pombe cyclin gene clg1+ by direct selection of long-lived mutants. PLoS One 2013; 8:e69084. [PMID: 23874875 PMCID: PMC3711543 DOI: 10.1371/journal.pone.0069084] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 06/12/2013] [Indexed: 11/30/2022] Open
Abstract
Model organisms such as budding yeast, worms and flies have proven instrumental
in the discovery of genetic determinants of aging, and the fission yeast
Schizosaccharomyces
pombe is a promising new system for these
studies. We devised an approach to directly select for long-lived
S.
pombe mutants from a random DNA insertion
library. Each insertion mutation bears a unique sequence tag called a bar code
that allows one to determine the proportion of an individual mutant in a culture
containing thousands of different mutants. Aging these mutants in culture
allowed identification of a long-lived mutant bearing an insertion mutation in
the cyclin gene clg1+. Clg1p, like
Pas1p, physically associates with the cyclin-dependent kinase Pef1p. We
identified a third Pef1p cyclin, Psl1p, and found that only loss of Clg1p or
Pef1p extended lifespan. Genetic and co-immunoprecipitation results indicate
that Pef1p controls lifespan through the downstream protein kinase Cek1p. While
Pef1p is conserved as Pho85p in Saccharomyces
cerevisiae, and as cdk5 in humans, genome-wide
searches for lifespan regulators in S. cerevisiae have
never identified Pho85p. Thus, the S. pombe system
can be used to identify novel, evolutionarily conserved lifespan extending
mutations, and our results suggest a potential role for mammalian cdk5 as a
lifespan regulator.
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Affiliation(s)
- Bo-Ruei Chen
- Department of Molecular Genetics, Cleveland Clinic Lerner College of
Medicine at Case Western Reserve University, Cleveland, Ohio,
USA
- Department of Genetics and Genome Sciences, Case Western Reserve
University School of Medicine, Cleveland, Ohio, United States of
America
- Department of Biochemistry, Case Western Reserve University School of
Medicine, Cleveland, Ohio, United States of America
| | - Yanhui Li
- Department of Molecular Genetics, Cleveland Clinic Lerner College of
Medicine at Case Western Reserve University, Cleveland, Ohio,
USA
- Department of Genetics and Genome Sciences, Case Western Reserve
University School of Medicine, Cleveland, Ohio, United States of
America
| | - Jessica R. Eisenstatt
- Department of Molecular Genetics, Cleveland Clinic Lerner College of
Medicine at Case Western Reserve University, Cleveland, Ohio,
USA
- Department of Biochemistry, Case Western Reserve University School of
Medicine, Cleveland, Ohio, United States of America
| | - Kurt W. Runge
- Department of Molecular Genetics, Cleveland Clinic Lerner College of
Medicine at Case Western Reserve University, Cleveland, Ohio,
USA
- Department of Genetics and Genome Sciences, Case Western Reserve
University School of Medicine, Cleveland, Ohio, United States of
America
- * E-mail:
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Futatsugi A, Utreras E, Rudrabhatla P, Jaffe H, Pant HC, Kulkarni AB. Cyclin-dependent kinase 5 regulates E2F transcription factor through phosphorylation of Rb protein in neurons. Cell Cycle 2012; 11:1603-10. [PMID: 22456337 DOI: 10.4161/cc.20009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recent studies have shown the involvement of cyclin-dependent kinase 5 (Cdk5) in cell cycle regulation in postmitotic neurons. In this study, we demonstrate that Cdk5 and its co-activator p35 were detected in the nuclear fraction in neurons and Cdk5/p35 phosphorylated retinoblastoma (Rb) protein, a key protein controlling cell cycle re-entry. Cdk5/p35 phosphorylates Rb at the sites similar to those phosphorylated by Cdk4 and Cdk2. Furthermore, increased Cdk5 activity elevates activity of E2F transcription factor, which can trigger cell cycle re-entry, leading to neuronal cell death. A normal Cdk5 activity in neurons did not induce E2F activation, suggesting that Cdk5 does not induce cell cycle re-entry under normal conditions. Taken together, these results indicate that Cdk5 can regulate cell cycle by its ability to phosphorylate Rb. Most importantly, increased Cdk5 activity induces cell cycle re-entry, which is especially detrimental for survival of postmitotic neurons.
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Affiliation(s)
- Akira Futatsugi
- Functional Genomics Section, Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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20
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McLinden KA, Trunova S, Giniger E. At the Fulcrum in Health and Disease: Cdk5 and the Balancing Acts of Neuronal Structure and Physiology. ACTA ACUST UNITED AC 2012; 2012:001. [PMID: 25364642 PMCID: PMC4212508 DOI: 10.4172/2168-975x.s1-001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cdk5 has been implicated in a multitude of processes in neuronal development, cell biology and physiology. These influence many neurological disorders, but the very breadth of Cdk5 effects has made it difficult to synthesize a coherent picture of the part played by this protein in health and disease. In this review, we focus on the roles of Cdk5 in neuronal function, particularly synaptic homeostasis, plasticity, neurotransmission, subcellular organization, and trafficking. We then discuss how disruption of these Cdk5 activities may initiate or exacerbate neural disorders. A recurring theme will be the sensitivity of Cdk5 sequelae to the precise biological context under consideration.
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Affiliation(s)
- Kristina A McLinden
- National Institute of Neurological Disorders and Stroke, USA ; National Human Genome Research Institute, USA
| | - Svetlana Trunova
- National Institute of Neurological Disorders and Stroke, USA ; National Human Genome Research Institute, USA
| | - Edward Giniger
- National Institute of Neurological Disorders and Stroke, USA ; National Human Genome Research Institute, USA
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