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Yao M, Rosario ER, Soper JC, Pike CJ. Androgens Regulate Tau Phosphorylation Through Phosphatidylinositol 3-Kinase-Protein Kinase B-Glycogen Synthase Kinase 3β Signaling. Neuroscience 2022:S0306-4522(22)00335-9. [PMID: 35777535 PMCID: PMC9797620 DOI: 10.1016/j.neuroscience.2022.06.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/11/2022] [Accepted: 06/23/2022] [Indexed: 12/31/2022]
Abstract
Age-related testosterone depletion in men is a risk factor for Alzheimer's disease (AD). How testosterone modulates AD risk remains to be fully elucidated, although regulation of tau phosphorylation has been suggested as a contributing protective action. To investigate the relationship between testosterone and tau phosphorylation, we first evaluated the effect of androgen status on tau phosphorylation in 3xTg-AD mice. Depletion of endogenous androgens via gonadectomy resulted in increased tau phosphorylation that was prevented by acute testosterone treatment. Parallel alterations in the phosphorylation of both glycogen synthase kinase 3β (GSK3β) and protein kinase B (Akt) suggest possible components of the underlying signaling pathway. To further explore mechanism, primary cultured neurons were treated with a physiological concentration of testosterone or its active metabolite dihydrotestosterone (DHT). Results showed that testosterone and DHT induced significant decreases in phosphorylated tau and significant increases in phosphorylation of Akt and GSK3β. Pharmacological inhibition of phosphatidylinositol 3-kinase (PI3K) effectively inhibited androgen-induced increases in Akt and GSK3β phosphorylation, and decreases in tau phosphorylation. In addition, androgen receptor (AR) knock-down by small interfering RNA prevented androgen-induced changes in the phosphorylation of Akt, GSK3β and tau, suggesting an AR-dependent mechanism. Additional experiments demonstrated androgen-induced changes in Akt, GSK3β and tau phosphorylation in AR-expressing PC12 cells but not in AR-negative PC12 cells. Together, these results suggest an AR-dependent pathway involving PI3K-Akt-GSK3β signaling through which androgens can reduce tau phosphorylation. These findings identify an additional protective mechanism of androgens that can improve neural health and inhibit development of AD.
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Affiliation(s)
- Mingzhong Yao
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
| | - Emily R Rosario
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
| | - Jenna Carroll Soper
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA
| | - Christian J Pike
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA.
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2
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Cdc-Like Kinases (CLKs): Biology, Chemical Probes, and Therapeutic Potential. Int J Mol Sci 2020; 21:ijms21207549. [PMID: 33066143 PMCID: PMC7593917 DOI: 10.3390/ijms21207549] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022] Open
Abstract
Protein kinases represent a very pharmacologically attractive class of targets; however, some members of the family still remain rather unexplored. The biology and therapeutic potential of cdc-like kinases (CLKs) have been explored mainly over the last decade and the first CLK inhibitor, compound SM08502, entered clinical trials only recently. This review summarizes the biological roles and therapeutic potential of CLKs and their heretofore published small-molecule inhibitors, with a focus on the compounds' potential to be utilized as quality chemical biology probes.
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3
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Cortés N, Guzmán-Martínez L, Andrade V, González A, Maccioni RB. CDK5: A Unique CDK and Its Multiple Roles in the Nervous System. J Alzheimers Dis 2019; 68:843-855. [DOI: 10.3233/jad-180792] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Nicole Cortés
- Laboratory of Neurosciences, Faculty of Sciences, University of Chile, Santiago, Chile
- International Center for Biomedicine (ICC), Santiago, Chile
| | - Leonardo Guzmán-Martínez
- Laboratory of Neurosciences, Faculty of Sciences, University of Chile, Santiago, Chile
- International Center for Biomedicine (ICC), Santiago, Chile
| | - Víctor Andrade
- Laboratory of Neurosciences, Faculty of Sciences, University of Chile, Santiago, Chile
- International Center for Biomedicine (ICC), Santiago, Chile
| | - Andrea González
- Laboratory of Neurosciences, Faculty of Sciences, University of Chile, Santiago, Chile
- International Center for Biomedicine (ICC), Santiago, Chile
| | - Ricardo B. Maccioni
- Laboratory of Neurosciences, Faculty of Sciences, University of Chile, Santiago, Chile
- International Center for Biomedicine (ICC), Santiago, Chile
- Department of Neurological Sciences, Faculty of Medicine, East Campus, University of Chile, Santiago, Chile
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4
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Park SJ, Kim E, Yoo M, Lee JY, Park CH, Hwang JY, Ha JD. Synthesis and biological evaluation of N9-cis-cyclobutylpurine derivatives for use as cyclin-dependent kinase (CDK) inhibitors. Bioorg Med Chem Lett 2017; 27:4399-4404. [DOI: 10.1016/j.bmcl.2017.08.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 08/08/2017] [Accepted: 08/10/2017] [Indexed: 12/17/2022]
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5
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Lloret A, Fuchsberger T, Giraldo E, Viña J. Molecular mechanisms linking amyloid β toxicity and Tau hyperphosphorylation in Alzheimer׳s disease. Free Radic Biol Med 2015; 83:186-91. [PMID: 25746773 DOI: 10.1016/j.freeradbiomed.2015.02.028] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 12/12/2022]
Abstract
Neurofibrillary tangles (aggregates of cytoskeletal Tau protein) and senile plaques (aggregates mainly formed by amyloid β peptide) are two landmark lesions in Alzheimer׳s disease. Some researchers have proposed tangles, whereas others have proposed plaques, as primary lesions. For a long time, these were thought of as independent mechanisms. However, experimental evidence suggests that both lesions are intimately related. We review here some molecular pathways linking amyloid β and Tau toxicities involving, among others, glycogen synthase kinase 3β, p38, Pin1, cyclin-dependent kinase 5, and regulator of calcineurin 1. Understanding amyloid β and Tau toxicities as part of a common pathophysiological mechanism may help to find molecular targets to prevent or even treat the disease.
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Affiliation(s)
- A Lloret
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain
| | - T Fuchsberger
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain
| | - E Giraldo
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain
| | - J Viña
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain.
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6
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de Thonel A, Ferraris SE, Pallari HM, Imanishi SY, Kochin V, Hosokawa T, Hisanaga SI, Sahlgren C, Eriksson JE. Protein kinase Czeta regulates Cdk5/p25 signaling during myogenesis. Mol Biol Cell 2010; 21:1423-34. [PMID: 20200223 PMCID: PMC2854099 DOI: 10.1091/mbc.e09-10-0847] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Atypical protein kinase Cζ (PKCζ) is emerging as a mediator of differentiation. Here, we describe a critical role for PKCζ during myogenic differentiation. Our results identify PKCζ as a controller of myogenic differentiation by its regulation of Cdk5. Atypical protein kinase Cζ (PKCζ) is emerging as a mediator of differentiation. Here, we describe a novel role for PKCζ in myogenic differentiation, demonstrating that PKCζ activity is indispensable for differentiation of both C2C12 and mouse primary myoblasts. PKCζ was found to be associated with and to regulate the Cdk5/p35 signaling complex, an essential factor for both neuronal and myogenic differentiation. Inhibition of PKCζ activity prevented both myotube formation and simultaneous reorganization of the nestin intermediate filament cytoskeleton, which is known to be regulated by Cdk5 during myogenesis. p35, the Cdk5 activator, was shown to be a specific phosphorylation target of PKCζ. PKCζ-mediated phosphorylation of Ser-33 on p35 promoted calpain-mediated cleavage of p35 to its more active and stable fragment, p25. Strikingly, both calpain activation and the calpain-mediated cleavage of p35 were shown to be PKCζ-dependent in differentiating myoblasts. Overall, our results identify PKCζ as a controller of myogenic differentiation by its regulation of the phosphorylation-dependent and calpain-mediated p35 cleavage, which is crucial for the amplification of the Cdk5 activity that is required during differentiation.
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Affiliation(s)
- Aurélie de Thonel
- Turku Centre for Biotechnology, University of Turku and Abo Akademi University, 20521 Turku, Finland
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7
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Stieler JT, Bullmann T, Kohl F, Barnes BM, Arendt T. PHF-like tau phosphorylation in mammalian hibernation is not associated with p25-formation. J Neural Transm (Vienna) 2009; 116:345-50. [PMID: 19184336 DOI: 10.1007/s00702-008-0181-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Accepted: 12/19/2008] [Indexed: 01/03/2023]
Abstract
In Alzheimer's disease and related disorders, hyperphosphorylation of tau is associated with an increased activity of cyclin dependent kinase 5 (cdk5). Elevated cdk5 activity is thought to be due to the formation of p25 and thereby represents a critical element in the dysregulation of tau phosphorylation under pathological conditions. However, there is still a controversy regarding the correlation of p25 generation and tau pathology. Recently, we demonstrated physiological, paired helical filament-like tau phosphorylation that reversibly occurs in hibernating mammals. Here we used this model to test whether the tau phosphorylation in hibernation is associated with the formation of p25. Analysing brain material of arctic ground squirrels and Syrian hamsters we found no evidence for a hibernation dependent generation of p25. Hence, we suppose that phosphorylation of tau does not require the formation of p25. Instead we suggest that the truncation of p35 to p25 represents a characteristic of pathological alterations and may contribute to aggregation and deposition of hyperphosphorylated tau.
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Affiliation(s)
- Jens Thorsten Stieler
- Department of Molecular and Cellular Mechanisms of Neurodegeneration, Paul Flechsig Institute of Brain Research, University of Leipzig, Jahnallee 59, 04109, Leipzig, Germany.
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8
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He Y, Kastin AJ, Hsuchou H, Pan W. The Cdk5/p35 kinases modulate leptin-induced STAT3 signaling. J Mol Neurosci 2009; 39:49-58. [PMID: 19156541 DOI: 10.1007/s12031-008-9174-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 12/18/2008] [Indexed: 10/21/2022]
Abstract
Cyclin-dependent kinase (Cdk) 5 is ubiquitously expressed in the brain and plays an essential role in central nervous system development and synaptic plasticity. The p35 kinase is a neuronal specific activator of Cdk5. Here, we show for the first time that Cdk5 activation modulates leptin signaling. P35 and its metabolite p25 were colocalized with the leptin receptor ObR in selective neurons in the hypothalamus. Overexpression of p35 alone was sufficient to induce the transcriptional activation of signal transducer and activator of transcription 3 (STAT3) in a cellular model. In retinoic acid-differentiated SH-SY5Y neuronal cells where ObRb was induced, leptin increased the expression of Cdk5, p35, and p25 kinases. The time course of induction coincided with that of phosphorylated (p)-STAT3. When Cdk5 activity was inhibited, either by roscovitine or overexpression of dominant negative Cdk5, there was a reduction of pSTAT3 activation. The results show that the activation of Cdk5 by p35 sustained leptin-induced pSTAT3 at 3-6 h. Thus, p35 is a novel modulator of leptin-induced STAT3 signaling.
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Affiliation(s)
- Yi He
- Blood-Brain Barrier Group, Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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9
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Connell-Crowley L, Vo D, Luke L, Giniger E. Drosophila lacking the Cdk5 activator, p35, display defective axon guidance, age-dependent behavioral deficits and reduced lifespan. Mech Dev 2007; 124:341-9. [PMID: 17368005 PMCID: PMC2045698 DOI: 10.1016/j.mod.2007.02.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 02/07/2007] [Accepted: 02/08/2007] [Indexed: 10/23/2022]
Abstract
The cyclin-dependent kinase Cdk5 has attracted a great deal of attention both because of its roles in cell migration and axon patterning, and the extensive data implicating it in adult-onset neurodegeneration in mammals. Both the kinase activity and the biological effects of Cdk5 are absolutely dependent on association with an activating subunit, called p35. We show here that Drosophila lacking the Cdk5 activator, D-p35, display a wide range of defects in embryonic axon patterning. We further show that, while viable and fertile, p35 mutant adults display progressive, age-dependent loss of motor function and have a significantly shortened lifespan.
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Affiliation(s)
- Lisa Connell-Crowley
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program National Institute of Neurological Disorders and Stroke (NINDS), and, National Human Genome Research Institute (NHGRI), National Institutes of Health, Bldg 37, Rm 1016, 37 Convent Drive Bethesda, MD 20892
| | - Duc Vo
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program National Institute of Neurological Disorders and Stroke (NINDS), and, National Human Genome Research Institute (NHGRI), National Institutes of Health, Bldg 37, Rm 1016, 37 Convent Drive Bethesda, MD 20892
| | - Lori Luke
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program National Institute of Neurological Disorders and Stroke (NINDS), and, National Human Genome Research Institute (NHGRI), National Institutes of Health, Bldg 37, Rm 1016, 37 Convent Drive Bethesda, MD 20892
| | - Edward Giniger
- Axon Guidance and Neural Connectivity Unit, Basic Neuroscience Program National Institute of Neurological Disorders and Stroke (NINDS), and, National Human Genome Research Institute (NHGRI), National Institutes of Health, Bldg 37, Rm 1016, 37 Convent Drive Bethesda, MD 20892
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10
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Li T, Chalifour LE, Paudel HK. Phosphorylation of Protein Phosphatase 1 by Cyclin-dependent Protein Kinase 5 during Nerve Growth Factor-induced PC12 Cell Differentiation. J Biol Chem 2007; 282:6619-28. [PMID: 17202132 DOI: 10.1074/jbc.m606347200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The transcription factor Egr-1 activates cyclin-dependent protein kinase 5 (Cdk5) during nerve growth factor (NGF)-induced differentiation of PC12 cells into neurons (Harada, T. Morooka, T., Ogawa, S., and Nishida, E. (2001) Nat. Cell Biol. 3, 453-459). The downstream target of Cdk5 in the Egr-1/Cdk5 pathway is not clear. In this study, we observed that phosphorylation of protein phosphatase 1 (PP1) on Thr(320) is reduced in brain extracts from Egr-1(-/-) mice, indicating that a kinase downstream of Egr-1 phosphorylates PP1. In HEK 293 cells co-transfected with PP1 and Cdk5, Cdk5 phosphorylates PP1. In vitro, Cdk5 purified from bovine brain phosphorylates bacterially expressed recombinant PP1. In NGF-treated PC12 cells, inhibition of Cdk5 by olomoucine or silencing Cdk5 expression by small interfering RNA strategy, suppresses PP1 phosphorylation. Silencing Cdk5 expression by small interfering RNA also blocks NGF-induced neurite outgrowth. Overexpression of PP1 (wild type) promotes NGF-induced differentiation of PC12 cells, whereas that of PP1 (T320A) has no effect. Our data indicate that PP1 is a downstream target of the NGF/Egr-1/Cdk5 pathway during NGF-induced differentiation of PC12 cells and suggest that PP1 phosphorylation promotes neuronal differentiation.
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Affiliation(s)
- Tong Li
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Canada
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11
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Andorfer C, Acker CM, Kress Y, Hof PR, Duff K, Davies P. Cell-cycle reentry and cell death in transgenic mice expressing nonmutant human tau isoforms. J Neurosci 2006; 25:5446-54. [PMID: 15930395 PMCID: PMC6725006 DOI: 10.1523/jneurosci.4637-04.2005] [Citation(s) in RCA: 368] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mutations in the microtubule-associated protein tau gene have been linked to neurofibrillary tangle (NFT) formation in several neurodegenerative diseases known as tauopathies; however, no tau mutations occur in Alzheimer's disease, although this disease is also characterized by NFT formation and cell death. Importantly, the mechanism of tau-mediated neuronal death remains elusive. Aged mice expressing nonmutant human tau in the absence of mouse tau (htau mice) developed NFTs and extensive cell death. The mechanism of neuron death was investigated in htau mice, and surprisingly, the presence of tau filaments did not correlate directly with death within individual cells, suggesting that cell death can occur independently of NFT formation. Our observations show that the mechanism of neurodegeneration involved reexpression of cell-cycle proteins and DNA synthesis, indicating that nonmutant tau pathology and neurodegeneration may be linked via abnormal, incomplete cell-cycle reentry.
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Affiliation(s)
- Cathy Andorfer
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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12
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Habran L, Bontems S, Di Valentin E, Sadzot-Delvaux C, Piette J. Varicella-zoster virus IE63 protein phosphorylation by roscovitine-sensitive cyclin-dependent kinases modulates its cellular localization and activity. J Biol Chem 2005; 280:29135-43. [PMID: 15955820 DOI: 10.1074/jbc.m503312200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During the first stage of Varicella-Zoster virus (VZV) infection, IE63 (immediate early 63 protein) is mostly expressed in the nucleus and also slightly in the cytoplasm, and during latency, IE63 localizes in the cytoplasm quite exclusively. Because phosphorylation is known to regulate various cellular mechanisms, we investigated the impact of phosphorylation by roscovitine-sensitive cyclin-dependent kinase (RSC) on the localization and functional properties of IE63. We demonstrated first that IE63 was phosphorylated on Ser-224 in vitro by CDK1 and CDK5 but not by CDK2, CDK7, or CDK9. Furthermore, by using roscovitine and CDK1 inhibitor III (CiIII), we showed that CDK1 phosphorylated IE63 on Ser-224 in vivo. By mutagenesis and the use of inhibitors, we demonstrated that phosphorylation on Ser-224 was important for the correct localization of the protein. Indeed, the substitution of these residues by alanine led to an exclusive nuclear localization of the protein, whereas mutations into glutamic acid did not modify its subcellular distribution. When transfected or VZV-infected cells were treated with roscovitine or CiIII, an exclusive nuclear localization of IE63 was also observed. By using a transfection assay, we also showed that phosphorylation on Ser-224 and Thr-222 was essential for the down-regulation of the basal activity of the VZV DNA polymerase gene promoter. Similarly, roscovitine and CiIII impaired these properties of the wild-type form of IE63. These observations clearly demonstrated the importance of CDK1-mediated IE63 phosphorylation for a correct distribution of IE63 between both cellular compartments and for its repressive activity toward the promoter tested.
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Affiliation(s)
- Lionel Habran
- Laboratory of Virology and Immunology, Center for Biomedical Genoproteomics, Institute of Pathology B23, University of Liège, B-4000, Liège, Belgium
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13
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Jossin Y. Neuronal migration and the role of reelin during early development of the cerebral cortex. Mol Neurobiol 2005; 30:225-51. [PMID: 15655250 DOI: 10.1385/mn:30:3:225] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Accepted: 04/29/2004] [Indexed: 11/11/2022]
Abstract
During development, neurons migrate to the cortex radially from periventricular germinative zones as well as tangentially from ganglionic eminences. The vast majority of cortical neurons settle radially in the cortical plate. Neuronal migration requires an exquisite regulation of leading edge extension, nuclear translocation (nucleokinesis), and retraction of trailing processes. During the past few years, several genes and proteins have been identified that are implicated in neuronal migration. Many have been characterized by reference to known mechanisms of neuronal and non-neuronal cell migration in culture; however, probably the most interesting have been identified by gene inactivation or modification in mice and by positional cloning of brain malformation genes in humans and mice. Although it is impossible to provide a fully integrated view, some patterns clearly emerge and are the subject of this article. Specific emphasis is placed on three aspects: first, the role of the actin treadmill, with cyclic formation of filopodial and lamellipodial extensions, in relation to surface events that occur at the leading edge of radially migrating neurons; second, the regulation of microtubule dynamics, which seems to play a key role in nucleokinesis; and third, the mechanisms by which the extracellular protein Reelin regulates neuronal positioning at the end of migration.
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Affiliation(s)
- Yves Jossin
- Developmental Neurobiology Unit, University of Louvain Medical School, Brussels, Belgium.
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14
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Lee A, Maldonado M, Baybis M, Walsh CA, Scheithauer B, Yeung R, Parent J, Weiner HL, Crino PB. Markers of cellular proliferation are expressed in cortical tubers. Ann Neurol 2003; 53:668-73. [PMID: 12731003 DOI: 10.1002/ana.10579] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
p34cdc2, collapsin response mediator protein 4 (CRMP4), doublecortin (DCX), HuD, and NeuN expression was assessed in tuber (n = 16) and subependymal giant cell astrocytoma (SEGA; n = 6) specimens in tuberous sclerosis complex to define the developmental phenotype and lineage of giant cells (CGs) in these lesions. Many GCs exhibited HuD and NeuN immunolabeling suggesting a differentiated neural phenotype. Giant cells in tubers, SEGAs and subependymal nodules in the Eker rat model of TSC expressed CRMP4 and DCX. Tubers and SEGAs exhibit a heterogeneous profile of differentiation and may share a common cellular lineage. Tubers may contain a subpopulation of newly generated cells.
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Affiliation(s)
- Allana Lee
- Department of Neurology, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA
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15
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Negash S, Wang HS, Gao C, Ledee D, Zelenka P. Cdk5 regulates cell-matrix and cell-cell adhesion in lens epithelial cells. J Cell Sci 2002; 115:2109-17. [PMID: 11973352 DOI: 10.1242/jcs.115.10.2109] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cdk5 is a member of the cyclin-dependent kinase family, which is expressed predominantly in terminally differentiated neurons. Lower levels of Cdk5 are also found in a wide variety of cell types, including the lens. Although Cdk5 has been shown to play an important role in neuronal migration and neurite outgrowth, its function in non-neuronal cells is not known. Therefore, this study was undertaken to explore the role of Cdk5 in the lens. Results showed that, within the adult mouse lens, Cdk5 was localized to the cytoplasm,especially along the lateral membranes of differentiating primary fiber cells,which suggests a role in cell-cell adhesion. Staining at the tips of elongating fiber cells was also particularly strong, suggesting a role in cell-matrix adhesion. To examine the possible role of Cdk5 in lens epithelial cell adhesion, we stably transfected N/N1003A rabbit lens epithelial cells with cDNAs for Cdk5 or a dominant-negative mutation, Cdk5-T33. Attachment to a fibronectin matrix, as measured with substrate-coated cell adhesion strips,was increased by Cdk5 overexpression, while an equivalent overexpression of Cdk5-T33 had no effect. Cdk5 also increased the rate of cell attachment and spreading as measured by electric cell-substrate impedance sensing (ECIS). In addition, Cdk5 overexpression decreased cell-cell adhesion as measured by a cell aggregation assay. These findings suggest that Cdk5 plays a role in regulating both cell-matrix and cell-cell interactions in the lens.
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Affiliation(s)
- Sewite Negash
- National Eye Institute, NIH, Bethesda, MD 20892, USA
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16
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Stull ND, Polan DP, Iacovitti L. Antioxidant compounds protect dopamine neurons from death due to oxidative stress in vitro. Brain Res 2002; 931:181-5. [PMID: 11897104 DOI: 10.1016/s0006-8993(02)02269-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Using tissue culture models of oxidative stress caused by serum deprivation or MPTP/MPP+ toxicity, the present study establishes that the antioxidants epigallocatechin gallate, lazaroids U74389G and U83836E, reservatrol, MnTBAP, MCI 186, trolox, and melatonin protect 68-100% of dopamine (DA) neurons from cell death. In contrast, the nitric oxide inhibitor LY83583, the caspase inhibitors Z-VAD-FMK, Ac-DQMD-CHO and Z-DEVD-FMK, and the CDK-5 inhibitor, roscovotine were not neuroprotective, although death was often delayed by 1 day in vitro. We conclude that antioxidants are more effective at preventing cell death in vitro than are inhibitors at later stages in the death cascade.
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Affiliation(s)
- Natalie D Stull
- Department of Neurology, Thomas Jefferson University Medical College, Philadelphia, PA 19107, USA
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17
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Vincent I, Bu B, Hudson K, Husseman J, Nochlin D, Jin L. Constitutive Cdc25B tyrosine phosphatase activity in adult brain neurons with M phase-type alterations in Alzheimer's disease. Neuroscience 2001; 105:639-50. [PMID: 11516829 DOI: 10.1016/s0306-4522(01)00219-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Cdc2/cyclin B kinase is a critical regulator of mitosis that is normally absent from terminally differentiated neurons of adult brain. However, unscheduled expression and activation of Cdc2/cyclin B has been seen in neurons undergoing degeneration in Alzheimer's disease. The presence of this mitotic kinase correlates with accumulation of mitotic phosphoepitopes in protein components of the hallmark neurofibrillary tangles. Of importance to the pathogenic mechanism of Alzheimer's disease is the striking appearance of Cdc2/cyclin B and mitotic phosphoepitopes prior to neurofibrillary tangle formation, which has suggested that a misappropriate mitotic cascade initiates and mediates the neurodegenerative process. To explain the atypical activation of Cdc2/cyclin B in degenerating neurons we have investigated the enzyme responsible for Cdc2/cyclin B activation in mitotic cells, i.e. the Cdc25B tyrosine phosphatase, in Alzheimer's disease brain. Although the enzyme appeared abundant in affected neurons, it was also evident in unaffected neurons of Alzheimer's disease and control brain. Thus, we have found, surprisingly, that Cdc25B is a normal constituent of adult brain neurons, with detectable basal levels of activity. In Alzheimer's disease the levels and activity of the enzyme are elevated, and the active enzyme predominates in the cytoplasmic compartment of neurons. Consistent with these M phase-type changes, Cdc25B displays increased immunoreactivity towards the MPM-2 mitotic phosphoepitope antibody. We propose that aberrant expression of Cdc2/cyclin B in Alzheimer's disease leads to potentiation of mitotic activation mediated by constitutive neuronal Cdc25B activity. As a result, various downstream indices of mitotic events are generated, eventually culminating in neurodegeneration. Our data also suggest that Cdc25B is functional in normal post-mitotic neurons lacking the mitotic Cdc2/cyclin B, but it does not appear to influence the activity of Cdk5, a Cdc2-like kinase that is particularly enriched in brain.
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Affiliation(s)
- I Vincent
- Department of Pathology, University of Washington, K056 HSB, P.O. Box 357705, Seattle, WA 98195, USA.
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18
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Lim HY, Seow KT, Li Q, Kesuma D, Wang JH, Qi RZ. Structural Insights into Cdk5 activation by a neuronal Cdk5 activator. Biochem Biophys Res Commun 2001; 285:77-83. [PMID: 11437375 DOI: 10.1006/bbrc.2001.5086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although Cdk5 shows high sequence identity to Cdk1 and Cdk2, it can be fully activated by its neuronal activators p35/p25(nck5a) and p39(nck5ai) in a phosphorylation-independent manner. To understand structural basis of the Cdk5/p25(nck5a) activation, the complex is modelled to assume either an obstructed or an opened conformation based on X-ray structures of the unphosphorylated or the phosphorylated Cdk2/cyclin A complex, respectively. Comparison and analysis of the two models, along with mutagenesis studies of p25(nck5a), suggest that the opened form represents more closely the structure of active Cdk5/p25(nck5a). The results provide a rationale basis for understanding the phosphorylation-independent activation of Cdk5/p25(nck5a).
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Affiliation(s)
- H Y Lim
- The Proteomics Group, Institute of Molecular and Cell Biology, 30 Medical Drive, 117609, Singapore
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19
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Agarwal-Mawal A, Paudel HK. Neuronal Cdc2-like protein kinase (Cdk5/p25) is associated with protein phosphatase 1 and phosphorylates inhibitor-2. J Biol Chem 2001; 276:23712-8. [PMID: 11320080 DOI: 10.1074/jbc.m010002200] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase 1 (PP1) is complexed with inhibitor 2 (I-2) in the cytosol. In rabbit muscle extract PP1.I-2 is activated upon preincubation with ATP/Mg. This activation is caused by phosphorylation of I-2 on Thr(72) by glycogen synthase kinase 3 (GSK3). We have found that PP1.I-2 in bovine brain extract is also activated upon preincubation with ATP/Mg. However, blocking GSK3 action by LiCl inhibited only approximately 29% of PP1 activity and indicated that GSK3 is not the sole PP1.I-2 activator in the brain. When bovine brain extract was analyzed by gel filtration PP1.I-2 and neuronal Cdc2-like protein kinase (NCLK), a heterodimer of Cdk5 and the regulatory p25 subunit, co-eluted as a approximately 450-kDa size species. The NCLK from the eluted column fractions bound to PP1-specific microcystin-Sepharose and glutathione S-transferase (GST)-I-2-coated glutathione-agarose beads. Similarly, PP1 from the eluted column fractions was pulled down with GST-Cdk5-coated glutathione-agarose beads. In vitro, NCLK phosphorylated I-2 on Thr(72) and activated PP1.I-2 in an ATP/Mg-dependent manner. NCLK bound to PP1 through its Cdk5 subunit and the PP1 binding region was localized to Cdk5 residues 28-41. Our data demonstrate that in brain extract PP1.I-2 and NCLK are associated within a complex of approximately 450 kDa and suggest that NCLK is one of the PP1.I-2-activating kinases in the mammalian brain.
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Affiliation(s)
- A Agarwal-Mawal
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Quebec, H3T 1E2, Canada
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20
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Neystat M, Rzhetskaya M, Oo TF, Kholodilov N, Yarygina O, Wilson A, El-Khodor BF, Burke RE. Expression of cyclin-dependent kinase 5 and its activator p35 in models of induced apoptotic death in neurons of the substantia nigra in vivo. J Neurochem 2001; 77:1611-25. [PMID: 11413244 DOI: 10.1046/j.1471-4159.2001.00376.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cyclin-dependent kinase 5 is predominantly expressed in postmitotic neurons and plays a role in neurite elongation during development. It has also been postulated to play a role in apoptosis in a variety of cells, including neurons, but little is known about the generality and functional significance of cdk5 expression in neuronal apoptosis in living brain. We have therefore examined its expression and that of its known activators, p35, p39 and p67, in models of induced apoptosis in neurons of the substantia nigra. We find that cdk5 is expressed in apoptotic profiles following intrastriatal injection of 6-hydroxydopamine and axotomy. It is expressed exclusively in profiles which are in late morphologic stages of apoptosis. In these late stages, derivation of the profiles from neurons, and localization of expression to the nucleus, can be demonstrated by co-labeling with a neuron-specific nuclear marker, NeuN. In another model of induced apoptotic death in nigra, produced by developmental striatal lesion, kinase activity increases in parallel with cell death. While mRNAs for all three cdk5 activators are expressed in nigra during development, only p35 protein is expressed in apoptotic profiles. We conclude that cdk5/p35 expression is a general feature of apoptotic neuron death in substantia nigra neurons in vivo.
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Affiliation(s)
- M Neystat
- Departments of Neurology and Pathology, The College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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21
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Nguyen MD, Larivière RC, Julien JP. Deregulation of Cdk5 in a mouse model of ALS: toxicity alleviated by perikaryal neurofilament inclusions. Neuron 2001; 30:135-47. [PMID: 11343650 DOI: 10.1016/s0896-6273(01)00268-9] [Citation(s) in RCA: 271] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent studies suggest that increased activity of cyclin-dependent kinase 5 (Cdk5) may contribute to neuronal death and cytoskeletal abnormalities in Alzheimer's disease. We report here such deregulation of Cdk5 activity associated with the hyperphosphorylation of tau and neurofilament (NF) proteins in mice expressing a mutant superoxide dismutase (SOD1(G37R)) linked to amyotrophic lateral sclerosis (ALS). A Cdk5 involvement in motor neuron degeneration is supported by our analysis of three SOD1(G37R) mouse lines exhibiting perikaryal inclusions of NF proteins. Our results suggest that perikaryal accumulations of NF proteins in motor neurons may alleviate ALS pathogenesis by acting as a phosphorylation sink for Cdk5 activity, thereby reducing the detrimental hyperphosphorylation of tau and other neuronal substrates.
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Affiliation(s)
- M D Nguyen
- Centre for Research in Neurosciences, McGill University, Research Institute of the McGill University, Health Centre, H3G 1A4, Montreal, Quebec, Canada
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22
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Wu DC, Yu YP, Lee NT, Yu AC, Wang JH, Han YF. The expression of Cdk5, p35, p39, and Cdk5 kinase activity in developing, adult, and aged rat brains. Neurochem Res 2000; 25:923-9. [PMID: 10959488 DOI: 10.1023/a:1007544106645] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The expression of cyclin-dependent kinase 5 (Cdk5) and its regulatory subunits, p35 and p39, was investigated in rat brain from embryonic day 12 (E12) to postnatal 18 months (18M). The Cdk5 protein levels increased from E12 to postnatal day 7 (P7) and remained at this level until 18M. The Cdk5 kinase activity and the levels of both p35 mRNA and protein were low at E12, became prominent at E18-P14 but then decreased in the adult and aged rat brains of 3M to 18M. In comparison, the expression pattern of p39 appeared to have an inverse relationship to that of Cdk5 and p35. In regional distribution studies, p35 protein levels and Cdk5 kinase activity were significantly higher in the cerebral cortex and hippocampus, but lower in the cerebellum and striatum. These results suggested that Cdk5, p35 and p39 might have region-specific and developmental stage-specific functions in rat brain.
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Affiliation(s)
- D C Wu
- Department of Biochemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, China
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23
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Sobue K, Agarwal-Mawal A, Li W, Sun W, Miura Y, Paudel HK. Interaction of neuronal Cdc2-like protein kinase with microtubule-associated protein tau. J Biol Chem 2000; 275:16673-80. [PMID: 10749861 DOI: 10.1074/jbc.m000784200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal Cdc2-like protein kinase (NCLK), a approximately 58-kDa heterodimer, was isolated from neuronal microtubules (Ishiguro, K., Takamatsu, M., Tomizawa, K., Omori, A., Takahashi, M., Arioka, M., Uchida, T. and Imahori, K. (1992) J. Biol. Chem. 267, 10897-10901). The biochemical nature of NCLK-microtubule association is not known. In this study we found that NCLK is released from microtubules upon microtubule disassembly as a 450-kDa species. The 450-kDa species is an NCLK.tau complex, and NCLK-bound tau is in a nonphosphorylated state. Tau phosphorylation causes NCLK.tau complex dissociation, and phosphorylated tau does not bind to NCLK. In vitro, the Cdk5 subunit of NCLK binds to the microtubule-binding region of tau and NCLK associates with microtubules only in the presence of tau. Our data indicate that in brain extract NCLK is complexed with tau in a tau phosphorylation-dependent manner and that tau anchors NCLK to microtubules. Recently NCLK has been suggested to be aberrantly activated and to hyperphosphorylate tau in Alzheimer's disease brain (Patrick, G. N., Zukerberg, L., Nikolic, M., de la Monte, S., Dikkes, P, and Tsai, L.-H. (1999) Nature 402, 615-622). Our findings may explain why in Alzheimer's disease NCLK specifically hyperphosphorylates tau, although this kinase has a number of protein substrates in the brain.
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Affiliation(s)
- K Sobue
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3T 1E2, Canada
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24
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Abstract
Although the role of intraneuronal neurofilamentous aggregates in the pathogenesis of ALS is unknown, their presence forms a key neuropathological hallmark of the disease process. Conversely, the experimental induction of neurofilamentous aggregates in either neurotoxic or transgenic mice gives rise to motor system degeneration. To determine whether alterations in the physiochemical properties of NF are present in sporadic ALS, we purified NF subunit proteins from cervical spinal cord of ALS and age-matched control patients. The cytoskeleton-enriched, Triton X-100 insoluble fraction was further separated into individual NF subunits using hydroxyapatite HPLC. We observed no differences between control and ALS in the characteristics of NFH, including migration patterns on 2D-IEF, sensitivity to E. coli, alkaline phosphatase mediated dephosphorylation, peptide mapping, or proteolysis (calpain, calpain/calmodulin mediated, phosphorylated or dephosphorylated NFH). NFL showed no differences in 2D-IEF migration patterns, peptide mapping, or the extent of NFL nitrotyrosine immunoreactivity in either the Triton soluble or insoluble fractions. The latter observation demonstrated that NFL nitration is a ubiquitous occurrence in neurons and suggests that NFL might function as a sink for free reactive nitrating species. In contrast to the lack of differences in the post-translational processing of NF in ALS, we did observe a selective suppression of NFL steady state mRNA levels in the limb innervating lateral motor neuron column of ALS. This occurred in the absence of modifications in NFH, NFM or neuronal nitric oxide synthase (Type I NOS; nNOS) steady state mRNA levels. Coupled with previous observations of nNOS immunoreactivity co-localizing with NF aggregates in ALS motor neurons, this suggests activation of the nNOS enzyme complex in ALS, which would be predicted to contribute directly to the generation of reactive nitrating species. Given this, the isolated suppression of NFL steady state mRNA levels in ALS may indicate that ALS motor neurons are at an intrinsic deficit in the ability to buffer free reactive nitrating species.
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Affiliation(s)
- M J Strong
- The John P Robarts Research Institute, and the Department of Clinical Neurological Sciences, The University of Western Ontario, London, Ontario, Canada.
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25
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Ye M, Duus KM, Peng J, Price DH, Grose C. Varicella-zoster virus Fc receptor component gI is phosphorylated on its endodomain by a cyclin-dependent kinase. J Virol 1999; 73:1320-30. [PMID: 9882337 PMCID: PMC103956 DOI: 10.1128/jvi.73.2.1320-1330.1999] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) glycoprotein gI is a type 1 transmembrane glycoprotein which is one component of the heterodimeric gE:gI Fc receptor complex. Like VZV gE, VZV gI was phosphorylated in both VZV-infected cells and gI-transfected cells. Preliminary studies demonstrated that a serine 343-proline 344 sequence located within the gI cytoplasmic tail was the most likely phosphorylation site. To determine which protein kinase catalyzed the gI phosphorylation event, we constructed a fusion protein, consisting of glutathione-S-transferase (GST) and the gI cytoplasmic tail, called GST-gI-wt. When this fusion protein was used as a substrate for gI phosphorylation in vitro, the results demonstrated that GST-gI-wt fusion protein was phosphorylated by a representative cyclin-dependent kinase (CDK) called P-TEFb, a homologue of CDK1 (cdc2). When serine 343 within the serine-proline phosphorylation site was replaced with an alanine residue, the level of phosphorylation of the gI fusion protein was greatly reduced. Subsequent experiments with individually immunoprecipitated mammalian CDKs revealed that the VZV gI fusion protein was phosphorylated best by CDK1, to a lesser degree by CDK2, and not at all by CDK6. Transient-transfection assays carried out in the presence of the specific CDK inhibitor roscovitine strongly supported the prior results by demonstrating a marked decrease in gI phosphorylation while gI protein expression was unaffected. Finally, the possibility that VZV gI contained a CDK phosphorylation site in its endodomain was of further interest because its partner, gE, contains a casein kinase II phosphorylation site in its endodomain; prior studies have established that CDK1 can phosphorylate casein kinase II.
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Affiliation(s)
- M Ye
- Departments of Microbiology, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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26
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Nagy Z. Mechanisms of neuronal death in Down's syndrome. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 1999; 57:233-45. [PMID: 10666679 DOI: 10.1007/978-3-7091-6380-1_15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
There is growing evidence that neuronal death in Down's syndrome is due to apoptotic mechanisms. The phenomena, however, that trigger and regulate programmed cell death in the Down's syndrome-related neurodegeneration are still much debated. In vitro evidence has suggested that the main factor responsible for neuronal death in this condition is the accumulation of beta-amyloid, due to the overexpression of its precursor protein. Another hypothesis argues for the importance of reactive oxygen species in neuronal death. However, the in vivo findings do not entirely support either theories. We propose that neuronal apoptosis, as well as the formation of Alzheimer-type pathology, in Down's syndrome is due to an aberrant re-entry of neurones into the cell division cycle. Due to the simultaneous overexpression of conflicting cell cycle regulatory signals the mitogenic amyloid precursor and the differentiation factor S100, the cell cycle is abandoned. Subsequently the cell cycle arrest may lead to either the formation of Alzheimer-related pathology or to apoptotic cell death.
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Affiliation(s)
- Z Nagy
- Department of Neuropathology, University of Oxford, United Kingdom.
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27
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Li W, Ma KK, Sun W, Paudel HK. Phosphorylation sensitizes microtubule-associated protein tau to Al(3+)-induced aggregation. Neurochem Res 1998; 23:1467-76. [PMID: 9821149 DOI: 10.1007/bf03181171] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In Alzheimer's disease the microtubule-associated protein tau becomes hyperphosphorylated and aggregates into paired helical filaments (PHFs). Although the biochemical basis of the aggregation of tau into PHFs is not very clear, Al3+ has been suggested to play some role. Previous studies have shown that Al3+ alters the phosphorylation state and causes aggregation of tau in experimental animals and cultured neurons. In this study Al3+ inhibited phosphorylation of tau by neuronal cdc2-like kinase and dephosphorylation of phosphorylated tau by phosphatase 2B. These inhibitions are very likely due to Al(3+)-induced aggregations of various proteins present in phosphorylation/dephosphorylation assay mixtures since Al3+ caused aggregations of all proteins examined. Furthermore, compared to other proteins, tau displayed only an average sensitivity towards Al(3+)-induced aggregation. However upon phosphorylation, tau's sensitivity towards Al3+ increased 3.5 fold. In the presence of the metal chelator EDTA, Al(3+)-induced aggregates of tau became soluble, whereas Al(3+)-induced phosphorylated tau aggregates were insoluble in the buffer containing EDTA and remained insensitive to proteolysis. Our data suggest that phosphorylation sensitizes tau to Al3+ and phosphorylated tau transforms irreversibly into a phosphatase and protease resistant aggregate in presence of this metal ion.
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Affiliation(s)
- W Li
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
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28
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A role for cyclin-dependent kinase(s) in the modulation of fast anterograde axonal transport: effects defined by olomoucine and the APC tumor suppressor protein. J Neurosci 1998. [PMID: 9742142 DOI: 10.1523/jneurosci.18-19-07717.1998] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Proteins that interact with both cytoskeletal and membrane components are candidates to modulate membrane trafficking. The tumor suppressor proteins neurofibromin (NF1) and adenomatous polyposis coli (APC) both bind to microtubules and interact with membrane-associated proteins. The effects of recombinant NF1 and APC fragments on vesicle motility were evaluated by measuring fast axonal transport along microtubules in axoplasm from squid giant axons. APC4 (amino acids 1034-2844) reduced only anterograde movements, whereas APC2 (aa 1034-2130) or APC3 (aa 2130-2844) reduced both anterograde and retrograde transport. NF1 had no effect on organelle movement in either direction. Because APC contains multiple cyclin-dependent kinase (CDK) consensus phosphorylation motifs, the kinase inhibitor olomoucine was examined. At concentrations in which olomoucine is specific for cyclin-dependent kinases (5 microM), it reduced only anterograde transport, whereas anterograde and retrograde movement were both affected at concentrations at which other kinases are inhibited as well (50 microM). Both anterograde and retrograde transport also were inhibited by histone H1 and KSPXK peptides, substrates for proline-directed kinases, including CDKs. Our data suggest that CDK-like axonal kinases modulate fast anterograde transport and that other axonal kinases may be involved in modulating retrograde transport. The specific effect of APC4 on anterograde transport suggests a model in which the binding of APC to microtubules may limit the activity of axonal CDK kinase or kinases in restricted domains, thereby affecting organelle transport.
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Abstract
Degenerative disorders of the basal ganglia are characterized by disturbances of motor control. Prototypic examples are Parkinson's disease, which is caused by degeneration of dopamine neurons of the substantia nigra, and Huntington's disease, which is caused by degeneration of neurons of the striatum. In recent years, it has been postulated that some of these disorders may be caused by programmed cell death or apoptosis, a genetically regulated form of cell death. There is clear evidence that apoptosis occurs in neurons of the basal ganglia during normal development, that it can be regulated, and that it can be induced in some animal models of these disorders. Although there is some suggestive direct evidence that apoptosis may occur in the human brain in these disorders, the evidence to date is partial and not yet compelling. Nevertheless, programmed cell death is an important new hypothesis for the pathogenesis of these disorders and warrants vigorous further investigation, particularly with molecular markers in addition to classic morphological markers. The concept of programmed cell death is relevant not only to the pathogenesis of these diseases but also to therapeutic issues, such as transplantation approaches.
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Affiliation(s)
- Robert E. Burke
- Neurological Institute College of Physicians and Surgeons Columbia University New York, New York
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30
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Shirvan A, Ziv I, Zilkha-Falb R, Machlyn T, Barzilai A, Melamed E. Expression of cell cycle-related genes during neuronal apoptosis: is there a distinct pattern? Neurochem Res 1998; 23:767-77. [PMID: 9566617 DOI: 10.1023/a:1022415611545] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An emerging hypothesis considers the process of neuronal apoptosis as a consequence of unscheduled and unsynchronized induction of cell cycle mediators. Induction of several cell cycle genes precedes neuronal apoptosis and may be involved in determination of cell fate. We have now characterized changes in expression of cell cycle genes during apoptosis induced by oxidative stress in chick post-mitotic sympathetic neurons. Induction of cyclin B occurred prior to the commitment of neurons to both dopamine- and peroxide-triggered apoptosis. Both the neuronal death and the rise in cyclin B were inhibited by antioxidant treatment, suggesting a functional role for cyclin B induction during neuronal apoptosis. Induction of the cyclin dependent kinase CDK5 protein coincided with the time point when neurons were irreversibly committed to die. Expression of other cell cycle mediators such as cyclin D1 and the cyclin dependent kinases CDC2 and CDK2 was undetected and not induced by exposure to oxidative stress. Comparative analysis of the profile of cell cycle mediators induced during neuronal apoptosis of different neuronal cell populations revealed no distinct pattern of events. There are no cell cycle stage-specific mediators that are ultimately stimulated during neuronal apoptosis, suggesting that multiple pathways of re-activating the dormant cell-cycle, converge to determine entry into apoptosis. Nevertheless, the existence of some cell cycle mediators, that were not reported so far to be induced in post mitotic neurons during oxidative stress, substantiate them as part of the strong differentiating forces.
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Affiliation(s)
- A Shirvan
- Department of Neurology and Felsenstein Medical Research Center, Rabin Medical Center, Beilinson Campus, Petach Tikva, Israel
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31
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Shuang R, Zhang L, Fletcher A, Groblewski GE, Pevsner J, Stuenkel EL. Regulation of Munc-18/syntaxin 1A interaction by cyclin-dependent kinase 5 in nerve endings. J Biol Chem 1998; 273:4957-66. [PMID: 9478941 DOI: 10.1074/jbc.273.9.4957] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Munc-18-syntaxin 1A complex has been postulated to act as a negative control on the regulated exocytotic process because its formation blocks the interaction of syntaxin with vesicle SNARE proteins. However, the formation of this complex is simultaneously essential for the final stages of secretion as evidenced by the necessity of Munc-18's homologues in Saccharomyces cerevisiae (Sec1p), Drosophila (ROP), and Caenorhabditis elegans (Unc-18) for proper secretion in these organisms. As such, any event that regulates the interaction of these two proteins is important for the control of secretion. One candidate for such regulation is cyclin-dependent kinase 5 (Cdk5), a member of the Cdc2 family of cell division cycle kinases that has recently been copurified with Munc-18 from rat brain. The present study shows that Cdk5 bound to its neural specific activator p35 not only binds to Munc-18 but utilizes it as a substrate for phosphorylation. Furthermore, it is demonstrated that Munc-18 that has been phosphorylated by Cdk5 has a significantly reduced affinity for syntaxin 1A. Finally, it is shown that Cdk5 can also bind to syntaxin 1A and that a complex of Cdk5, p35, Munc-18, and syntaxin 1A can be fashioned in the absence of ATP and promptly disassembled upon the addition of ATP. These results suggest a model in which p35-activated Cdk5 becomes localized to the Munc-18-syntaxin 1A complex by its affinity for both proteins so that it may phosphorylate Munc-18 and thus permit the positive interaction of syntaxin 1A with upstream protein effectors of the secretory mechanism.
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Affiliation(s)
- R Shuang
- Department of Physiology, University of Michigan, Ann Arbor, Michigan 48109-0622, USA
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32
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Paudel HK. Phosphorylation by neuronal cdc2-like protein kinase promotes dimerization of Tau protein in vitro. J Biol Chem 1997; 272:28328-34. [PMID: 9353289 DOI: 10.1074/jbc.272.45.28328] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In Alzheimer's disease, the microtubule-associated protein tau forms paired helical filaments (PHFs) that are the major structural component of neurofibrillary tangles. Although tau isolated from PHFs (PHF-tau) is abnormally phosphorylated, the role of this abnormal phosphorylation in PHF assembly is not known. Previously, neuronal cdc2-like protein kinase (NCLK) was shown to phosphorylate tau on sites that are abnormally phosphorylated in PHF-tau (Paudel, H. K., Lew, J., Ali, Z., and Wang, J. H. (1993) J. Biol. Chem. 268, 23512-23518). In this study, phosphorylation by NCLK was found to promote dimerization of recombinant human tau (R-tau) and brain tau (B-tau) purified from brain extract. Chemical cross-linking by disuccinimidyl suberate (DSS), a homobifunctional chemical cross-linker that specifically cross-linked R-tau dimers, and a Superose 12 gel filtration chromatography revealed that R-tau preparations contain mixtures of monomeric and dimeric R-tau species. When the structure of NCLK-phosphorylated R-tau was studied by a similar approach, DSS preferentially cross-linked the phosphorylated R-tau over the nonphosphorylated R-tau, and the phosphorylated R-tau eluted as a dimeric species from the gel filtration column. Phosphorylated R-tau became resistant to DSS upon dephosphorylation and was recovered as a monomeric species from the gel filtration column. In the presence of a low concentration of dithiothreitol (1.65 microM), R-tau formed disulfide cross-linked R-tau dimers. When compared, phosphorylated R-tau formed more disulfide cross-linked dimers than the nonphosphorylated R-tau. B-tau also was specifically cross-linked to dimers by DSS. When B-tau and NCLK-phosphorylated B-tau were treated with DSS, phosphorylated B-tau was preferentially cross-linked over nonphosphorylated counterpart. Taken together, these results suggest that phosphorylation by NCLK promotes dimerization and formation of disulfide cross-linked tau dimers, which is suggested to be the key step leading to PHF assembly (Schweers, O., Mandelkow, E.-M., Biernat, J., and Mandelkow, E. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 8463-8467).
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Affiliation(s)
- H K Paudel
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital and Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, H3T 1E2, Canada.
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Henchcliffe C, Burke RE. Increased expression of cyclin-dependent kinase 5 in induced apoptotic neuron death in rat substantia nigra. Neurosci Lett 1997; 230:41-4. [PMID: 9259459 DOI: 10.1016/s0304-3940(97)00472-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We reported previously that striatal excitotoxic lesion with quinolinic acid of rat pups during the first 2 weeks of postnatal life results in loss of dopaminergic neurons of the substantia nigra (SN) due to induced apoptosis. Here we demonstrate by immunohistochemistry that, following such a lesion, high levels of cyclin-dependent kinase 5 (cdk5) protein are present exclusively in apoptotic cells over and above basal levels of diffuse axonal staining. Furthermore, localization of high levels of cdk5 is associated also with normal developmental programmed cell death in the SN and other regions of the central nervous system, including the cerebral cortex. These findings suggest a novel role for cdk5 during neuron apoptosis and may provide insight into mechanisms of loss of dopaminergic neurons in Parkinson's disease.
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Affiliation(s)
- C Henchcliffe
- Department of Neurology, Columbia University, New York, NY 10032, USA
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Kinnaird JH, Mottram JC. Plasmodium cdc2-related kinases: Do they regulate stage differentiation? ACTA ACUST UNITED AC 1997; 13:7-8; discussion 38-9. [PMID: 15275159 DOI: 10.1016/s0169-4758(96)20058-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- J H Kinnaird
- Wellcome Unit or Molecular Parasitology. The Anderson College, University of Glasgow, 56 Dunbarton Road, Glasgow, UK
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35
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Tang D, Wang JH. Cyclin-dependent kinase 5 (Cdk5) and neuron-specific Cdk5 activators. PROGRESS IN CELL CYCLE RESEARCH 1996; 2:205-216. [PMID: 9552397 DOI: 10.1007/978-1-4615-5873-6_20] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
While cyclin-dependent kinase 5 (Cdk5) is widely distributed in mammalian tissues and in cultured cell lines, Cdk5-associated kinase activity has been demonstrated only in mammalian brains. An active form of Cdk5, called neuronal cdc2-like kinase (Nclk) has been purified from mammalian brain and shown to be a heterodimer of Cdk5 and a 25 kDa protein, which is derived proteolytically from a 35 kDa brain and neuron-specific protein. The protein is essential for the kinase activity of Cdk5 and is therefore designated neuronal Cdk5 activator, p25/35Nck5a. Nclk appears to have important neuronal functions. The changes in Cdk5 and Nck5a expression appear to correlate with the terminal differentiation of neurons of the mouse embryonic brain. Transfection of cultured cortical neurons with dominant negative cdk5 mutants or Nck5a antisense DNA may reduce neurite growth, suggesting that Nclk plays an active role in neuron differentiation. A number of cytoskeletal proteins including neurofilament proteins, the neuron-specific microtubule associated protein tau, and the actin binding protein caldesmon are in vitro substrates of Nclk. Although Nck5a has cyclin-like activity, it shows minimal amino acid sequence identity to members of cyclin family proteins. The mechanism of activation of Cdk5 by Nck5a differs from that of cyclin activation of Cdks in that full Cdk5 kinase activity can be achieved in the absence of phosphorylation of Cdk5. An isoform of Nck5a, a 39 kDa protein has been cloned and shown to share extensive amino acid identity and the mechanism of Cdk5 activation with Nck5a. These proteins may represent a subfamily of Cdk activators distinct from cyclins.
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Affiliation(s)
- D Tang
- Department of Biochemistry, Hong Kong University of Science and Technology, Kowloon, Hong Kong
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36
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Qi Z, Tang D, Matsuura I, Lee KY, Zhu X, Huang QQ, Wang JH. Regulatory properties of neuronal cdc2-like kinase. Mol Cell Biochem 1995; 149-150:35-9. [PMID: 8569747 DOI: 10.1007/bf01076561] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Neuronal cdc2-like kinase, nclk, is a heterodimer of cyclin dependent protein kinase 5, cdk5, and a 25 kDa subunit derived from a novel, neuron-specific, 35 kDa protein: p35. The characterization and regulation of nclk will be summarized in this minireview. The activity of nclk appears to be governed by highly complex regulatory mechanisms including protein-protein interaction, protein phosphorylation and isoforms. The histone H1 kinase activity of nclk is absolutely dependent of the interaction between the 25 kDa subunit and the catalytic subunit, cdk5. In addition, nclk interacts with other cellular proteins to form macromolecular complexes. The kinase activity of nclk is inhibited in vitro by the phosphorylation reactions of a weel-like protein tyrosine kinase and a protein serine/threonine kinase from bovine thymus. Northern blot analysis has revealed the existence of two populations of p35 mRNA of 2 and 4 kb. A novel cDNA encoding a p35 homologous protein has been obtained from a human hippocampus library.
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Affiliation(s)
- Z Qi
- Department of Medical Biochemistry, University of Calgary, Alberta, Canada
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