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Yang J, Liu Y, Yin H, Xie S, Zhang L, Dong X, Ni H, Bu W, Ma H, Liu P, Zhu H, Guo R, Sun L, Wu Y, Qin J, Sun B, Li D, Luo HR, Liu M, Xuan C, Zhou J. HDAC6 deacetylates IDH1 to promote the homeostasis of hematopoietic stem and progenitor cells. EMBO Rep 2023; 24:e56009. [PMID: 37642636 PMCID: PMC10561360 DOI: 10.15252/embr.202256009] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 07/27/2023] [Accepted: 08/14/2023] [Indexed: 08/31/2023] Open
Abstract
Hematopoietic stem and progenitor cells (HSPCs) are cells mainly present in the bone marrow and capable of forming mature blood cells. However, the epigenetic mechanisms governing the homeostasis of HSPCs remain elusive. Here, we demonstrate an important role for histone deacetylase 6 (HDAC6) in regulating this process. Our data show that the percentage of HSPCs in Hdac6 knockout mice is lower than in wild-type mice due to decreased HSPC proliferation. HDAC6 interacts with isocitrate dehydrogenase 1 (IDH1) and deacetylates IDH1 at lysine 233. The deacetylation of IDH1 inhibits its catalytic activity and thereby decreases the 5-hydroxymethylcytosine level of ten-eleven translocation 2 (TET2) target genes, changing gene expression patterns to promote the proliferation of HSPCs. These findings uncover a role for HDAC6 and IDH1 in regulating the homeostasis of HSPCs and may have implications for the treatment of hematological diseases.
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Affiliation(s)
- Jia Yang
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Yang Liu
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Hanxiao Yin
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Songbo Xie
- Center for Cell Structure and Function, College of Life Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of ShandongShandong Normal UniversityJinanChina
| | - Linlin Zhang
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Xifeng Dong
- Department of HematologyTianjin Medical University General HospitalTianjinChina
| | - Hua Ni
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Weiwen Bu
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Hongbo Ma
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Peng Liu
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeTianjinChina
| | - Haiyan Zhu
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeTianjinChina
| | - Rongxia Guo
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeTianjinChina
| | - Lei Sun
- Center for Cell Structure and Function, College of Life Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of ShandongShandong Normal UniversityJinanChina
| | - Yue Wu
- Center for Cell Structure and Function, College of Life Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of ShandongShandong Normal UniversityJinanChina
| | - Juan Qin
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Baofa Sun
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Dengwen Li
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
| | - Hongbo R Luo
- Department of Pathology, Department of Laboratory Medicine, Harvard Medical SchoolChildren's Hospital Boston, Dana‐Farber/Harvard Cancer CenterBostonMAUSA
| | - Min Liu
- Laboratory of Tissue HomeostasisHaihe Laboratory of Cell EcosystemTianjinChina
| | - Chenghao Xuan
- The Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical Epigenetics, Key Laboratory of Immune Microenvironment and Disease of the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Jun Zhou
- State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, Tianjin Key Laboratory of Protein Science, College of Life SciencesNankai UniversityTianjinChina
- Center for Cell Structure and Function, College of Life Sciences, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of ShandongShandong Normal UniversityJinanChina
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Ratto MH, Paiva L, Carrasco R, Silva ME, Ulloa-Leal C, Ratto VF, Goicochea J. Review: Unveiling the effect of beta-nerve growth factor on the reproductive function in llamas and cows. Animal 2023; 17 Suppl 1:100754. [PMID: 37567661 DOI: 10.1016/j.animal.2023.100754] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 02/17/2023] [Accepted: 02/23/2023] [Indexed: 08/13/2023] Open
Abstract
The actions of the beta-nerve growth factor (β-NGF) on the neuroendocrine and reproductive system have challenged classical views on the control of reproductive function. After endometrial absorption, β-NGF triggers ovulation and promotes the development of functional corpora lutea in camelids. In this article, we review evidence showing that, in camelids, β-NGF exerts its actions by acting in both the hypothalamus and the ovary. In the hypothalamus, β-NGF may induce gonadotropin-releasing hormone (GnRH) release by interacting with neurons or glial cells expressing receptors for β-NGF. The LH surge occurs under the influence of ovarian estradiol and requires the release of GnRH into the portal vessels to reach the pituitary gland. In the ovary, β-NGF may be promoting the differentiation of follicular to luteal cells by modifying the steroidogenic profile of ovarian follicular cells in both camelids and ruminants. Although the mechanisms for these actions are largely undetermined, we aim to offer an update on the current understanding of the effects of β-NGF controlling reproductive function in camelids and ruminants.
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Affiliation(s)
- Marcelo H Ratto
- Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Luis Paiva
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Rodrigo Carrasco
- Department of Chemistry, College of Arts and Science, University of Saskatchewan, Saskatoon, Canada
| | - Mauricio E Silva
- Departamento de Medicina Veterinaria y Salud Publica, Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile
| | - Cesar Ulloa-Leal
- Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Vicente F Ratto
- Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Jose Goicochea
- Departamento de Cirugía y Biotecnología Reproductiva, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Hermilio Valdizán, Huánuco, Perú
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3
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Hayne M, DiAntonio A. Protein phosphatase 2A restrains DLK signaling to promote proper Drosophila synaptic development and mammalian cortical neuron survival. Neurobiol Dis 2022; 163:105586. [PMID: 34923110 PMCID: PMC9359336 DOI: 10.1016/j.nbd.2021.105586] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/23/2021] [Accepted: 12/15/2021] [Indexed: 02/03/2023] Open
Abstract
Protein phosphatase 2A (PP2A) is a major cellular phosphatase with many protein substrates. As expected for a signaling molecule with many targets, inhibition of PP2A disrupts fundamental aspects of cellular physiology including cell division and survival. In post-mitotic neurons, the microtubule associated protein Tau is a particularly well-studied PP2A substrate as hyperphosphorylation of Tau is a hallmark of Alzheimer's disease. Although many cellular targets are likely altered by loss of PP2A, here we find that activation of a single pathway can explain important aspects of the PP2A loss-of-function phenotype in neurons. We demonstrate that PP2A inhibits activation of the neuronal stress kinase DLK and its Drosophila ortholog Wallenda. In the fly, PP2A inhibition activates a DLK/Wallenda-regulated transcriptional program that induces synaptic terminal overgrowth at the neuromuscular junction. In cultured mammalian neurons, PP2A inhibition activates a DLK-dependent apoptotic program that induces cell death. Since hyperphosphorylated Tau is toxic, we wished to test the hypothesis that dephosphorylation of Tau by PP2A is required for neuronal survival. Contrary to expectations, in the absence of Tau PP2A inhibition still activates DLK and induces neuronal cell death, demonstrating that hyperphosphorylated Tau is not required for cell death in this model. Moreover, hyperphosphorylation of Tau following PP2A inhibition does not require DLK. Hence, loss of PP2A function in cortical neurons triggers two independent neuropathologies: 1) Tau hyperphosphorylation and 2) DLK activation and subsequent neuronal cell death. These findings demonstrate that inhibition of the DLK pathway is an essential function of PP2A required for normal Drosophila synaptic terminal development and mammalian cortical neuron survival.
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Affiliation(s)
- Margaret Hayne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110
| | - Aaron DiAntonio
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110,Needleman Center for Neurometabolism and Axonal Therapeutics, Washington University School of Medicine, St. Louis, MO 63110
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Sandal P, Jong CJ, Merrill RA, Song J, Strack S. Protein phosphatase 2A - structure, function and role in neurodevelopmental disorders. J Cell Sci 2021; 134:270819. [PMID: 34228795 DOI: 10.1242/jcs.248187] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Neurodevelopmental disorders (NDDs), including intellectual disability (ID), autism and schizophrenia, have high socioeconomic impact, yet poorly understood etiologies. A recent surge of large-scale genome or exome sequencing studies has identified a multitude of mostly de novo mutations in subunits of the protein phosphatase 2A (PP2A) holoenzyme that are strongly associated with NDDs. PP2A is responsible for at least 50% of total Ser/Thr dephosphorylation in most cell types and is predominantly found as trimeric holoenzymes composed of catalytic (C), scaffolding (A) and variable regulatory (B) subunits. PP2A can exist in nearly 100 different subunit combinations in mammalian cells, dictating distinct localizations, substrates and regulatory mechanisms. PP2A is well established as a regulator of cell division, growth, and differentiation, and the roles of PP2A in cancer and various neurodegenerative disorders, such as Alzheimer's disease, have been reviewed in detail. This Review summarizes and discusses recent reports on NDDs associated with mutations of PP2A subunits and PP2A-associated proteins. We also discuss the potential impact of these mutations on the structure and function of the PP2A holoenzymes and the etiology of NDDs.
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Affiliation(s)
- Priyanka Sandal
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Chian Ju Jong
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Jianing Song
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242, USA
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5
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Pesaola F, Quassollo G, Venier AC, De Paul AL, Noher I, Bisbal M. The neuronal ceroid lipofuscinosis-related protein CLN8 regulates endo-lysosomal dynamics and dendritic morphology. Biol Cell 2021; 113:419-437. [PMID: 34021618 DOI: 10.1111/boc.202000016] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/18/2021] [Accepted: 05/22/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND INFORMATION The endo-lysosomal system (ELS) comprises a set of membranous organelles responsible for transporting intracellular and extracellular components within cells. Defects in lysosomal proteins usually affect a large variety of processes and underlie many diseases, most of them with a strong neuronal impact. Mutations in the endoplasmic reticulum-resident CLN8 protein cause CLN8 disease. This condition is one of the 14 known neuronal ceroid lipofuscinoses (NCLs), a group of inherited diseases characterised by accumulation of lipofuscin-like pigments within lysosomes. Besides mediating the transport of soluble lysosomal proteins, recent research suggested a role for CLN8 in the transport of vesicles and lipids, and autophagy. However, the consequences of CLN8 deficiency on ELS structure and activity, as well as the potential impact on neuronal development, remain poorly characterised. Therefore, we performed CLN8 knockdown in neuronal and non-neuronal cell models to analyse structural, dynamic and functional changes in the ELS and to assess the impact of CLN8 deficiency on axodendritic development. RESULTS CLN8 knockdown increased the size of the Golgi apparatus, the number of mobile vesicles and the speed of endo-lysosomes. Using the fluorescent fusion protein mApple-LAMP1-pHluorin, we detected significant lysosomal alkalisation in CLN8-deficient cells. In turn, experiments in primary rat hippocampal neurons showed that CLN8 deficiency decreased the complexity and size of the somatodendritic compartment. CONCLUSIONS Our results suggest the participation of CLN8 in vesicular distribution, lysosomal pH and normal development of the dendritic tree. We speculate that the defects triggered by CLN8 deficiency on ELS structure and dynamics underlie morphological alterations in neurons, which ultimately lead to the characteristic neurodegeneration observed in this NCL. SIGNIFICANCE This is, to our knowledge, the first characterisation of the effects of CLN8 dysfunction on the structure and dynamics of the ELS. Moreover, our findings suggest a novel role for CLN8 in somatodendritic development, which may account at least in part for the neuropathological manifestations associated with CLN8 disease.
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Affiliation(s)
- Favio Pesaola
- Programa de Investigación Translacional de Lipofuscinosis Ceroidea Neuronal, Hospital de Niños de Córdoba, Córdoba, 5014, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Médicas "Mercedes y Martin Ferreyra"- IMMF-UNC-CONICET, Laboratorio de Neurobiología, Av. Friuli 2434, 5016 Córdoba, Argentina, Universidad Nacional de Córdoba, Córdoba, 5000, Argentina
| | - Gonzalo Quassollo
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Médicas "Mercedes y Martin Ferreyra"- IMMF-UNC-CONICET, Laboratorio de Neurobiología, Av. Friuli 2434, 5016 Córdoba, Argentina, Universidad Nacional de Córdoba, Córdoba, 5000, Argentina
| | - Ana Clara Venier
- Programa de Investigación Translacional de Lipofuscinosis Ceroidea Neuronal, Hospital de Niños de Córdoba, Córdoba, 5014, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigación en Ciencias de la Salud (INICSA), Bv. de la Reforma y Enfermera Gordillo, Ciudad Universitaria, Córdoba, 5016, Argentina
| | - Ana Lucía De Paul
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigación en Ciencias de la Salud (INICSA), Bv. de la Reforma y Enfermera Gordillo, Ciudad Universitaria, Córdoba, 5016, Argentina.,Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Centro de Microscopía Electrónica, Bv. de la Reforma y Enfermera Gordillo, Ciudad Universitaria, Córdoba, 5016, Argentina
| | - Ines Noher
- Programa de Investigación Translacional de Lipofuscinosis Ceroidea Neuronal, Hospital de Niños de Córdoba, Córdoba, 5014, Argentina
| | - Mariano Bisbal
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Médicas "Mercedes y Martin Ferreyra"- IMMF-UNC-CONICET, Laboratorio de Neurobiología, Av. Friuli 2434, 5016 Córdoba, Argentina, Universidad Nacional de Córdoba, Córdoba, 5000, Argentina.,Instituto Universitario de Ciencias Biomédicas Córdoba, Córdoba, 5016, Argentina
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6
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Song J, Merrill RA, Usachev AY, Strack S. The X-linked intellectual disability gene product and E3 ubiquitin ligase KLHL15 degrades doublecortin proteins to constrain neuronal dendritogenesis. J Biol Chem 2020; 296:100082. [PMID: 33199366 PMCID: PMC7948412 DOI: 10.1074/jbc.ra120.016210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/27/2020] [Accepted: 11/16/2020] [Indexed: 11/13/2022] Open
Abstract
Proper brain development and function requires finely controlled mechanisms for protein turnover, and disruption of genes involved in proteostasis is a common cause of neurodevelopmental disorders. Kelch-like 15 (KLHL15) is a substrate adaptor for cullin3-containing E3 ubiquitin ligases, and KLHL15 gene mutations were recently described as a cause of severe X-linked intellectual disability. Here, we used a bioinformatics approach to identify a family of neuronal microtubule-associated proteins as KLHL15 substrates, which are themselves critical for early brain development. We biochemically validated doublecortin (DCX), also an X-linked disease protein, and doublecortin-like kinase 1 and 2 as bona fide KLHL15 interactors and mapped KLHL15 interaction regions to their tandem DCX domains. Shared with two previously identified KLHL15 substrates, a FRY tripeptide at the C-terminal edge of the second DCX domain is necessary for KLHL15-mediated ubiquitination of DCX and doublecortin-like kinase 1 and 2 and subsequent proteasomal degradation. Conversely, silencing endogenous KLHL15 markedly stabilizes these DCX domain-containing proteins and prolongs their half-life. Functionally, overexpression of KLHL15 in the presence of WT DCX reduces dendritic complexity of cultured hippocampal neurons, whereas neurons expressing FRY-mutant DCX are resistant to KLHL15. Collectively, our findings highlight the critical importance of the E3 ubiquitin ligase adaptor KLHL15 in proteostasis of neuronal microtubule-associated proteins and identify a regulatory network important for development of the mammalian nervous system.
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Affiliation(s)
- Jianing Song
- Department of Neuroscience and Pharmacology and the Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology and the Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
| | - Andrew Y Usachev
- Department of Neuroscience and Pharmacology and the Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA
| | - Stefan Strack
- Department of Neuroscience and Pharmacology and the Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa, USA.
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7
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Valderrama X, Ulloa-Leal C, Silva ME, Goicochea J, Apichela S, Argañaraz M, Sari L, Paiva L, Ratto VF, Ratto MH. β-NGF Stimulates Steroidogenic Enzyme and VEGFA Gene Expression, and Progesterone Secretion via ERK 1/2 Pathway in Primary Culture of Llama Granulosa Cells. Front Vet Sci 2020; 7:586265. [PMID: 33195615 PMCID: PMC7645075 DOI: 10.3389/fvets.2020.586265] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/07/2020] [Indexed: 01/19/2023] Open
Abstract
The beta-nerve growth factor (β-NGF) from llama seminal plasma exerts ovulatory and luteotrophic effects following intramuscular or intrauterine infusion in llamas and alpacas. In this study, we investigate the in vitro effect of llama β-NGF on the expression of genes involved in angiogenesis and progesterone synthesis as well as progesterone release in preovulatory llama granulosa cells; we also determine whether these changes are mediated via the ERK1/2 signaling pathway. From adult female llamas, we collected granulosa cells from preovulatory follicles by transvaginal ultrasound-guided follicle aspiration; these cells were pooled and incubated. After 80% confluence, the cultured granulosa cells were treated with β-NGF, β-NGF plus the MAPK inhibitor U0126, or luteinizing hormone, and the abundance of angiogenic and steroidogenic enzyme mRNA transcripts were quantified after 10 and 20 h by RT-qPCR. We also quantified the progesterone concentration in the media after 48 h by radioimmunoassay. We found that application of β-NGF increases the abundance of mRNA transcripts of the vascular endothelial growth factor (VEGFA) and the steroidogenic enzymes cytochrome P450 side-chain cleavage (P450scc/CYP11A1), steroidogenic acute regulatory protein (STAR), and 3β-hydroxysteroid dehydrogenase (HSD3B1) at 10 and 20 h of treatment. Application of the MAPK inhibitor U0126 resulted in downregulation of the genes encoding these enzymes. β-NGF also enhanced progesterone synthesis, which was prevented by the prior application of the MAPK inhibitor U0126. Finally, western blot analysis confirmed that β-NGF activates the ERK1/2 signaling pathway. In conclusion, our results indicate that β-NGF exerts direct luteotropic effects on llama ovarian tissue via the ERK 1/2 pathway.
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Affiliation(s)
| | - Cesar Ulloa-Leal
- Institute of Animal Science, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Mauricio Erciario Silva
- Department of Veterinary Sciences and Public Health, Faculty of Natural Resources, Universidad Catolica de Temuco, Temuco, Chile
| | - Jose Goicochea
- Department of Surgery and Reproductive Biotechnology, Faculty of Veterinary Medicine and Zootechnics, Universidad Nacional Hermilio Valdizán, Huánuco, Peru
| | - Silvana Apichela
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, Facultad de Bioquímica, Instituto de Biología "Dr. Francisco D. Barbieri," Química y Farmacia, UNT, San Miguel de Tucumán, Argentina
| | - Martin Argañaraz
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, Facultad de Bioquímica, Instituto de Biología "Dr. Francisco D. Barbieri," Química y Farmacia, UNT, San Miguel de Tucumán, Argentina
| | - Luciana Sari
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, Facultad de Bioquímica, Instituto de Biología "Dr. Francisco D. Barbieri," Química y Farmacia, UNT, San Miguel de Tucumán, Argentina
| | - Luis Paiva
- Institute of Animal Science, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Vicente Francisco Ratto
- Institute of Animal Science, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Marcelo Hector Ratto
- Institute of Animal Science, Faculty of Veterinary Sciences, Universidad Austral de Chile, Valdivia, Chile
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8
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Jong CJ, Merrill RA, Wilkerson EM, Herring LE, Graves LM, Strack S. Reduction of protein phosphatase 2A (PP2A) complexity reveals cellular functions and dephosphorylation motifs of the PP2A/B'δ holoenzyme. J Biol Chem 2020; 295:5654-5668. [PMID: 32156701 PMCID: PMC7186168 DOI: 10.1074/jbc.ra119.011270] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/21/2020] [Indexed: 12/17/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a large enzyme family responsible for most cellular Ser/Thr dephosphorylation events. PP2A substrate specificity, localization, and regulation by second messengers rely on more than a dozen regulatory subunits (including B/R2, B'/R5, and B″/R3), which form the PP2A heterotrimeric holoenzyme by associating with a dimer comprising scaffolding (A) and catalytic (C) subunits. Because of partial redundancy and high endogenous expression of PP2A holoenzymes, traditional approaches of overexpressing, knocking down, or knocking out PP2A regulatory subunits have yielded only limited insights into their biological roles and substrates. To this end, here we sought to reduce the complexity of cellular PP2A holoenzymes. We used tetracycline-inducible expression of pairs of scaffolding and regulatory subunits with complementary charge-reversal substitutions in their interaction interfaces. For each of the three regulatory subunit families, we engineered A/B charge-swap variants that could bind to one another, but not to endogenous A and B subunits. Because endogenous Aα was targeted by a co-induced shRNA, endogenous B subunits were rapidly degraded, resulting in expression of predominantly a single PP2A heterotrimer composed of the A/B charge-swap pair and the endogenous catalytic subunit. Using B'δ/PPP2R5D, we show that PP2A complexity reduction, but not PP2A overexpression, reveals a role of this holoenzyme in suppression of extracellular signal-regulated kinase signaling and protein kinase A substrate dephosphorylation. When combined with global phosphoproteomics, the PP2A/B'δ reduction approach identified consensus dephosphorylation motifs in its substrates and suggested that residues surrounding the phosphorylation site play roles in PP2A substrate specificity.
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Affiliation(s)
- Chian Ju Jong
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Ronald A Merrill
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242
| | - Emily M Wilkerson
- Michael Hooker Proteomics Facility, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Laura E Herring
- Michael Hooker Proteomics Facility, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Lee M Graves
- Michael Hooker Proteomics Facility, University of North Carolina, Chapel Hill, North Carolina 27516
| | - Stefan Strack
- Department of Neuroscience and Pharmacology and Iowa Neuroscience Institute, University of Iowa, Iowa City, Iowa 52242.
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9
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Biswas D, Cary W, Nolta JA. PPP2R5D-Related Intellectual Disability and Neurodevelopmental Delay: A Review of the Current Understanding of the Genetics and Biochemical Basis of the Disorder. Int J Mol Sci 2020; 21:ijms21041286. [PMID: 32074998 PMCID: PMC7072873 DOI: 10.3390/ijms21041286] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 12/14/2022] Open
Abstract
Protein Phosphatase 2 Regulatory Subunit B′ Delta (PPP2R5D)-related intellectual disability (ID) and neurodevelopmental delay results from germline de novo mutations in the PPP2R5D gene. This gene encodes the protein PPP2R5D (also known as the B56 delta subunit), which is an isoform of the subunit family B56 of the enzyme serine/threonine-protein phosphatase 2A (PP2A). Clinical signs include intellectual disability (ID); autism spectrum disorder (ASD); epilepsy; speech problems; behavioral challenges; and ophthalmologic, skeletal, endocrine, cardiac, and genital malformations. The association of defective PP2A activity in the brain with a wide range of severity of ID, along with its role in ASD, Alzheimer’s disease, and Parkinson’s-like symptoms, have recently generated the impetus for further research into mutations within this gene. PP2A, together with protein phosphatase 1 (PP1), accounts for more than 90% of all phospho-serine/threonine dephosphorylations in different tissues. The specificity for a wide variety of substrates is determined through nearly 100 different PP2A holoenzymes that are formed by at least 23 types of regulatory B subunits, and two isoforms each of the catalytic subunit C and the structural subunit A. In the mammalian brain, PP2A-mediated protein dephosphorylation plays an important role in learning and memory. The PPP2R5D subunit is highly expressed in the brain and the PPP2A–PPP2R5D holoenzyme plays an important role in maintaining neurons and regulating neuronal signaling. From 2015 to 2017, 25 individuals with PPP2R5D-related developmental disorder were diagnosed. Since then, Whole-Exome Sequencing (WES) has helped to identify more unrelated individuals clinically diagnosed with a neurodevelopmental disorder with pathological variants of PPP2R5D. In this review, we discuss the current understanding of the clinical and genetic aspects of the disorder in the context of the known functions of the PP2A–PPP2R5D holoenzyme in the brain, as well as the pathogenic mutations in PPP2R5D that lead to deficient PP2A–PPP2R5D dephosphorylation and their implications during development and in the etiology of autism, Parkinson’s disease, Alzheimer’s disease, and so forth. In the future, tools such as transgenic animals carrying pathogenic PPP2R5D mutations, and patient-derived induced pluripotent stem cell lines need to be developed in order to fully understand the effects of these mutations on different neural cell types.
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Affiliation(s)
- Dayita Biswas
- SPARK Program Scholar, Institute for Regenerative Cures, University of California, Sacramento, CA 95817, USA;
| | - Whitney Cary
- Stem Cell Program, UC Davis School of Medicine. The University of California, Sacramento, CA 95817, USA
- UC Davis Gene Therapy Program, University of California, Sacramento, CA 95817, USA
- Correspondence: (W.C.); (J.A.N.)
| | - Jan A. Nolta
- SPARK Program Scholar, Institute for Regenerative Cures, University of California, Sacramento, CA 95817, USA;
- Stem Cell Program, UC Davis School of Medicine. The University of California, Sacramento, CA 95817, USA
- UC Davis Gene Therapy Program, University of California, Sacramento, CA 95817, USA
- Correspondence: (W.C.); (J.A.N.)
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10
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Di Donato M, Cernera G, Migliaccio A, Castoria G. Nerve Growth Factor Induces Proliferation and Aggressiveness In Prostate Cancer Cells. Cancers (Basel) 2019; 11:E784. [PMID: 31174415 PMCID: PMC6627659 DOI: 10.3390/cancers11060784] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 12/20/2022] Open
Abstract
Resistance to hormone therapy and disease progression is the major challenge in clinical management of prostate cancer (PC). Drugs currently used in PC therapy initially show a potent antitumor effects, but PC gradually develops resistance, relapses and spreads. Most patients who fail primary therapy and have recurrences eventually develop castration-resistant prostate cancer (CRPC), which is almost incurable. The nerve growth factor (NGF) acts on a variety of non-neuronal cells by activating the NGF tyrosine-kinase receptor, tropomyosin receptor kinase A (TrkA). NGF signaling is deregulated in PC. In androgen-dependent PC cells, TrkA mediates the proliferative action of NGF through its crosstalk with the androgen receptor (AR). Epithelial PC cells, however, acquire the ability to express NGF and TrkA, as the disease progresses, indicating a role for NGF/TrkA axis in PC progression and androgen-resistance. We here report that once activated by NGF, TrkA mediates proliferation, invasiveness and epithelial-mesenchymal transition (EMT) in various CRPC cells. NGF promotes organoid growth in 3D models of CRPC cells, and specific inhibition of TrkA impairs all these responses. Thus TrkA represents a new biomarker to target in CRPC.
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Affiliation(s)
- Marzia Di Donato
- Department of Precision Medicine-University of Campania 'L. Vanvitelli'-via L. De Crecchio, 7-80138 Naples, Italy.
| | - Gustavo Cernera
- Department of Precision Medicine-University of Campania 'L. Vanvitelli'-via L. De Crecchio, 7-80138 Naples, Italy.
| | - Antimo Migliaccio
- Department of Precision Medicine-University of Campania 'L. Vanvitelli'-via L. De Crecchio, 7-80138 Naples, Italy.
| | - Gabriella Castoria
- Department of Precision Medicine-University of Campania 'L. Vanvitelli'-via L. De Crecchio, 7-80138 Naples, Italy.
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11
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Protein Phosphatase 2A: a Double-Faced Phosphatase of Cellular System and Its Role in Neurodegenerative Disorders. Mol Neurobiol 2017; 55:1750-1761. [PMID: 28224476 DOI: 10.1007/s12035-017-0444-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/03/2017] [Indexed: 12/17/2022]
Abstract
Protein phosphatase 2A (PP2A), a ubiquitously expressed serine/threonine phosphatase, is a vitally important phosphatase for the cellular system. Structurally, it is constituted of three different subunits, namely catalytic subunit (PP2Ac), structural scaffold subunit (PP2A-A), and regulatory subunit (PP2A-B). All subunits have various isoforms, and catalytic and scaffold subunits are ubiquitously expressed, whereas regulatory subunits are more specific to tissue and cell type. It is the numerous possibilities of PP2A holoenzyme assembly with varying isoform components that make it possess a dual nature of activator or the inhibitory character in different signaling pathways, namely neural developmental pathways, Akt/protein kinase B pathway, NF-kB pathway, MAPK pathway, apoptosis pathway, and cell cycle progression to name a few. Importantly, the expression of PP2A in the brain is highest among the serine phosphatases and is known to actively participate in the neural development process. However, the exact mechanism of action of PP2A is still debated and enunciating the holoenzyme components, especially the regulatory subunit of PP2A involved in regulating neural developmental process is still poorly understood. In this review, we try to throw some light on the involvement of various PP2A holoenzyme forms in the process of neurogenesis and progression of neurodegenerative diseases.
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12
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Xiong LL, Chen ZW, Wang TH. Nerve growth factor promotes in vitro proliferation of neural stem cells from tree shrews. Neural Regen Res 2016; 11:591-6. [PMID: 27212919 PMCID: PMC4870915 DOI: 10.4103/1673-5374.180743] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Neural stem cells promote neuronal regeneration and repair of brain tissue after injury, but have limited resources and proliferative ability in vivo. We hypothesized that nerve growth factor would promote in vitro proliferation of neural stem cells derived from the tree shrews, a primate-like mammal that has been proposed as an alternative to primates in biomedical translational research. We cultured neural stem cells from the hippocampus of tree shrews at embryonic day 38, and added nerve growth factor (100 μg/L) to the culture medium. Neural stem cells from the hippocampus of tree shrews cultured without nerve growth factor were used as controls. After 3 days, fluorescence microscopy after DAPI and nestin staining revealed that the number of neurospheres and DAPI/nestin-positive cells was markedly greater in the nerve growth factor-treated cells than in control cells. These findings demonstrate that nerve growth factor promotes the proliferation of neural stem cells derived from tree shrews.
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Affiliation(s)
- Liu-Lin Xiong
- Department of Anesthesiology, Institute of Neurological Disease, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China
| | - Zhi-Wei Chen
- Institute of Neuroscience, Kunming Medical University, Kunming, Yunnan Province, China; Key Laboratory of National Physical Fitness and Altitude Training Adaptation in Yunnan Province; Institute of Physical Education, Yunnan Normal University, Kunming, Yunnan Province, China
| | - Ting-Hua Wang
- Department of Anesthesiology, Institute of Neurological Disease, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China; Institute of Neuroscience, Kunming Medical University, Kunming, Yunnan Province, China; Key Laboratory of National Physical Fitness and Altitude Training Adaptation in Yunnan Province; Institute of Physical Education, Yunnan Normal University, Kunming, Yunnan Province, China
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13
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Abstract
Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.
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Affiliation(s)
- Nathan Wlodarchak
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| | - Yongna Xing
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
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14
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Qureshi O, Cho H, Choudhary M, Seeling JM. A Nonsynonymous/Synonymous Substitution Analysis of the B56 Gene Family Aids in Understanding B56 Isoform Diversity. PLoS One 2015; 10:e0145529. [PMID: 26692027 PMCID: PMC4687035 DOI: 10.1371/journal.pone.0145529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 12/04/2015] [Indexed: 11/18/2022] Open
Abstract
Gene duplication leads to the formation of gene families, wherein purifying or neutral selection maintains the original gene function, while diversifying selection confers new functions onto duplicated genes. The B56 gene family is highly conserved; it is encoded by one gene in protists and fungi, and five genes in vertebrates. B56 regulates protein phosphatase 2A (PP2A), an abundant heterotrimeric serine/threonine phosphatase that functions as a tumor suppressor and consists of a scaffolding “A” and catalytic “C” subunit heterodimer bound to a regulatory “B” subunit. Individual regulatory B56 subunits confer disparate functions onto PP2A in various cell-cell signaling pathways. B56 proteins share a conserved central core domain, but have divergent N- and C-termini which play a role in isoform specificity. We carried out a nonsynonymous/synonymous substitution analysis to better understand the divergence of vertebrate B56 genes. When five B56 paralogs from ten vertebrate species were analyzed, the gene family displayed purifying selection; stronger purifying selection was revealed when individual B56 isoforms were analyzed separately. The B56 core experienced stronger purifying selection than the N- and C-termini, which correlates with the presence of several contacts between the core and the AC heterodimer. Indeed, the majority of the contact points that we analyzed between B56 and the AC heterodimer experienced strong purifying selection. B56 subfamilies showed distinct patterns of selection in their N- and C-termini. The C-terminus of the B56-1 subfamily and the N-terminus of the B56-2 subfamily exhibited strong purifying selection, suggesting that these termini carry out subfamily-specific functions, while the opposite termini exhibited diversifying selection and likely carry out isoform-specific functions. We also found reduced synonymous substitutions at the N- and C-termini when grouping B56 genes by species but not by isoform, suggesting species-specific codon bias may have a role in regulating B56 gene expression.
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Affiliation(s)
- Osama Qureshi
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX, United States of America
| | - Hyuk Cho
- Department of Computer Science, Sam Houston State University, Huntsville, TX, United States of America
| | - Madhusudan Choudhary
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX, United States of America
| | - Joni M Seeling
- Department of Biological Sciences, Sam Houston State University, Huntsville, TX, United States of America
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15
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Rowland MA, Harrison B, Deeds EJ. Phosphatase specificity and pathway insulation in signaling networks. Biophys J 2015; 108:986-996. [PMID: 25692603 DOI: 10.1016/j.bpj.2014.12.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/13/2014] [Accepted: 12/05/2014] [Indexed: 12/31/2022] Open
Abstract
Phosphatases play an important role in cellular signaling networks by regulating the phosphorylation state of proteins. Phosphatases are classically considered to be promiscuous, acting on tens to hundreds of different substrates. We recently demonstrated that a shared phosphatase can couple the responses of two proteins to incoming signals, even if those two substrates are from otherwise isolated areas of the network. This finding raises a potential paradox: if phosphatases are indeed highly promiscuous, how do cells insulate themselves against unwanted crosstalk? Here, we use mathematical models to explore three possible insulation mechanisms. One approach involves evolving phosphatase KM values that are large enough to prevent saturation by the phosphatase's substrates. Although this is an effective method for generating isolation, the phosphatase becomes a highly inefficient enzyme, which prevents the system from achieving switch-like responses and can result in slow response kinetics. We also explore the idea that substrate degradation can serve as an effective phosphatase. Assuming that degradation is unsaturatable, this mechanism could insulate substrates from crosstalk, but it would also preclude ultrasensitive responses and would require very high substrate turnover to achieve rapid dephosphorylation kinetics. Finally, we show that adaptor subunits, such as those found on phosphatases like PP2A, can provide effective insulation against phosphatase crosstalk, but only if their binding to substrates is uncoupled from their binding to the catalytic core. Analysis of the interaction network of PP2A's adaptor domains reveals that although its adaptors may isolate subsets of targets from one another, there is still a strong potential for phosphatase crosstalk within those subsets. Understanding how phosphatase crosstalk and the insulation mechanisms described here impact the function and evolution of signaling networks represents a major challenge for experimental and computational systems biology.
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Affiliation(s)
- Michael A Rowland
- Center for Computational Biology, University of Kansas, Lawrence, Kansas
| | - Brian Harrison
- Center for Computational Biology, University of Kansas, Lawrence, Kansas
| | - Eric J Deeds
- Center for Computational Biology, University of Kansas, Lawrence, Kansas; Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas; Santa Fe Institute, Santa Fe, New Mexico.
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16
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Zanirati G, Azevedo PN, Marinowic DR, Rodrigues F, de Oliveira Dias AC, Venturin GT, Greggio S, Simão F, DaCosta JC. Transplantation of bone marrow mononuclear cells modulates hippocampal expression of growth factors in chronically epileptic animals. CNS Neurosci Ther 2015; 21:463-71. [PMID: 25645708 DOI: 10.1111/cns.12382] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 12/26/2014] [Accepted: 12/27/2014] [Indexed: 12/27/2022] Open
Abstract
AIMS In previous studies, transplantation of bone marrow mononuclear cells (BMMCs) in epileptic animals has been found to be neuroprotective. However, the mechanism by which the BMMCs act remains unclear. We hypothesize that BMMCs may provide neuroprotection to the epileptic brain through trophic support. To test our hypothesis, we studied the temporal expression of neurotrophins after BMMC transplantation in the epileptic rat hippocampus. METHODS Chronically epileptic rats were intravenously transplanted with 1 × 10(7) BMMCs isolated from GFP transgenic mice. Expression levels of BDNF, GDNF, NGF, VEGF, and TGF-β1, and their receptors, were evaluated by ELISA and/or qRT-PCR analysis. RESULTS Our data revealed increased protein expression of BDNF, GDNF, NGF, and VEGF and reduced levels of TGF-β1 in the hippocampus of transplanted epileptic animals. Additionally, an increase in the mRNA expression of BDNF, GDNF, and VEGF, a reduction in TGF-β1, and a decrease in mRNA levels of the TrkA and TGFR-β1 receptors were also observed. CONCLUSION The gain provided by transplanted BMMCs in the epileptic brain may be related to the ability of these cells in modulating the network of neurotrophins and angiogenic signals.
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Affiliation(s)
- Gabriele Zanirati
- PUCRS, Pós-Graduação em Medicina e Ciências da Saúde, Instituto do Cérebro do Rio Grande do Sul (InsCer), Instituto de Pesquisas Biomódicas, Laboratório de Neurociências e Sinalização Celular, Porto Alegre, RS, Brazil
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17
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Uren RT, Turnley AM. Regulation of neurotrophin receptor (Trk) signaling: suppressor of cytokine signaling 2 (SOCS2) is a new player. Front Mol Neurosci 2014; 7:39. [PMID: 24860421 PMCID: PMC4030161 DOI: 10.3389/fnmol.2014.00039] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 04/21/2014] [Indexed: 12/17/2022] Open
Abstract
The classic neurotrophins Nerve Growth Factor (NGF), Brain Derived Neurotrophic Factor (BDNF) and Neurotrophins NT-3 and NT-4 are well known to regulate various aspects of neuronal differentiation, survival and growth. They do this by binding to their cognate receptors, members of the Tropomyosin-related kinase (Trk) receptor tyrosine kinase family, namely TrkA, TrkB, and TrkC. These receptors are then internalized and localized to different cellular compartments, where signal transduction occurs. Conversely, members of the suppressor of cytokine signaling (SOCS) family are best known as negative regulators of signaling via the JAK/STAT pathway. Some members of the family, and in particular SOCS2, have roles in the nervous system that at least partially overlap with that of neurotrophins, namely neuronal differentiation and neurite outgrowth. Recent evidence suggests that SOCS2 is a novel regulator of NGF signaling, altering TrkA cellular localization and downstream signaling to affect neurite growth but not neuronal survival. This review first discusses regulation of Trk receptor signaling, followed by the role of SOCS2 in the nervous system and finishes with a discussion of possible mechanisms by which SOCS2 may regulate TrkA function.
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Affiliation(s)
- Rachel T Uren
- Neural Regeneration Laboratory, Centre for Neuroscience Research and Department of Anatomy and Neuroscience, The University of Melbourne Melbourne, VIC, Australia
| | - Ann M Turnley
- Neural Regeneration Laboratory, Centre for Neuroscience Research and Department of Anatomy and Neuroscience, The University of Melbourne Melbourne, VIC, Australia
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18
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Kawahara E, Maenaka S, Shimada E, Nishimura Y, Sakurai H. Dynamic regulation of extracellular signal-regulated kinase (ERK) by protein phosphatase 2A regulatory subunit B56γ1 in nuclei induces cell migration. PLoS One 2013; 8:e63729. [PMID: 23704935 PMCID: PMC3660565 DOI: 10.1371/journal.pone.0063729] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 04/05/2013] [Indexed: 01/25/2023] Open
Abstract
Extracellular signal-regulated kinase (ERK) signalling plays a central role in various biological processes, including cell migration, but it remains unknown what factors directly regulate the strength and duration of ERK activation. We found that, among the B56 family of protein phosphatase 2A (PP2A) regulatory subunits, B56γ1 suppressed EGF-induced cell migration on collagen, bound to phosphorylated-ERK, and dephosphorylated ERK, whereas B56α1 and B56β1 did not. B56γ1 was immunolocalized in nuclei. The IER3 protein was immediately highly expressed in response to costimulation of cells with EGF and collagen. Knockdown of IER3 inhibited cell migration and enhanced dephosphorylation of ERK. Analysis of the time course of PP2A-B56γ1 activity following the costimulation showed an immediate loss of phosphatase activity, followed by a rapid increase in activity, and this activity then remained at a stable level that was lower than the original level. Our results indicate that the strength and duration of the nuclear ERK activation signal that is initially induced by ERK kinase (MEK) are determined at least in part by modulation of the phosphatase activity of PP2A-B56γ1 through two independent pathways.
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Affiliation(s)
- Ei Kawahara
- Department of Clinical Laboratory Science, Kanazawa University, Kanazawa, Japan
- * E-mail:
| | - Shiori Maenaka
- Department of Clinical Laboratory Science, Kanazawa University, Kanazawa, Japan
| | - Eri Shimada
- Department of Clinical Laboratory Science, Kanazawa University, Kanazawa, Japan
| | - Yoshihiro Nishimura
- Department of Clinical Laboratory Science, Kanazawa University, Kanazawa, Japan
| | - Hiroshi Sakurai
- Department of Clinical Laboratory Science, Kanazawa University, Kanazawa, Japan
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19
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Sánchez I, Piñol P, Corral-Juan M, Pandolfo M, Matilla-Dueñas A. A novel function of Ataxin-1 in the modulation of PP2A activity is dysregulated in the spinocerebellar ataxia type 1. Hum Mol Genet 2013; 22:3425-37. [PMID: 23630944 DOI: 10.1093/hmg/ddt197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An expansion of glutamines within the human ataxin-1 protein underlies spinocerebellar ataxia type 1 (SCA1), a dominantly inherited neurodegenerative disorder characterized by ataxia and loss of cerebellar Purkinje neurons. Although the mechanisms linking the mutation to the disease remain unclear, evidence indicates that it involves a combination of both gain and loss of functions of ataxin-1. We previously showed that the mutant ataxin-1 interacts with Anp32a, a potent and selective PP2A inhibitor, suggesting a role of PP2A in SCA1. Herein, we found a new function of ataxin-1: the modulation of Pp2a activity and the regulation of its holoenzyme composition, with the polyglutamine mutation within Atxn1 altering this function in the SCA1 mouse cerebellum before disease onset. We show that ataxin-1 enhances Pp2a-bβ expression and down-regulates Anp32a levels without affecting post-translational modifications of Pp2a catalytic subunit (Pp2a-c) known to regulate Pp2a activity. In contrast, mutant Atxn1 induces a decrease in Y307-phosphorylation in Pp2a-c, known to enhance its activity, while reducing Pp2a-b expression and inhibiting Anp32a levels. qRT-PCR and chromatin immunoprecipitation analyses show that ataxin-1-mediated regulations of the Pp2a-bβ subunit, specifically bβ2, and of Anp32a occur at the transcriptional level. The Pp2a pathway alterations were confirmed by identified phosphorylation changes of the known Pp2a-substrates, Erk2 and Gsk3β. Similarly, mutant ataxin-1-expressing SH-SY5Y cells exhibit abnormal neuritic morphology, decreased levels of both PP2A-Bβ and ANP32A, and PP2A pathway alterations, all of which are ameliorated by overexpressing ANP32A. Our results point to dysregulation of this newly assigned function of ataxin-1 in SCA1 uncovering new potential targets for therapy.
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Affiliation(s)
- Ivelisse Sánchez
- Basic, Translational and Molecular Neurogenetics Research Unit in Neurosciences, Health Sciences Research Institute Germans Trias y Pujol (IGTP), Badalona, Barcelona, Spain
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Wang SH, Liao XM, Liu D, Hu J, Yin YY, Wang JZ, Zhu LQ. NGF promotes long-term memory formation by activating poly(ADP-ribose)polymerase-1. Neuropharmacology 2012; 63:1085-92. [DOI: 10.1016/j.neuropharm.2012.06.050] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Revised: 06/16/2012] [Accepted: 06/25/2012] [Indexed: 11/26/2022]
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Giannakopoulou D, Daguin-Nerrière V, Mitsacos A, Kouvelas ED, Neveu I, Giompres P, Brachet P. Ectopic expression of TrKA in the adult rat basal ganglia induces both nerve growth factor-dependent and -independent neuronal responses. J Neurosci Res 2012; 90:1507-21. [DOI: 10.1002/jnr.23031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/16/2011] [Accepted: 12/27/2011] [Indexed: 12/30/2022]
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Trakhtenberg EF, Goldberg JL. Epigenetic regulation of axon and dendrite growth. Front Mol Neurosci 2012; 5:24. [PMID: 22403528 PMCID: PMC3290832 DOI: 10.3389/fnmol.2012.00024] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 02/12/2012] [Indexed: 12/27/2022] Open
Abstract
Neuroregenerative therapies for central nervous system (CNS) injury, neurodegenerative disease, or stroke require axons of damaged neurons to grow and re-innervate their targets. However, mature mammalian CNS neurons do not regenerate their axons, limiting recovery in these diseases. Although neurons' intrinsic capacity for axon growth may depend in part on the panoply of expressed transcription factors, epigenetic factors such as the accessibility of DNA and organization of chromatin are required for downstream genes to be transcribed. Thus, a potential approach to overcoming regenerative failure focuses on the epigenetic mechanisms regulating regenerative gene expression in the CNS. Here we review molecular mechanisms regulating the epigenetic state of DNA through chromatin modifications, their implications for regulating axon and dendrite growth, and important new directions for this field of study.
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Braithwaite SP, Stock JB, Lombroso PJ, Nairn AC. Protein phosphatases and Alzheimer's disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:343-79. [PMID: 22340724 PMCID: PMC3739963 DOI: 10.1016/b978-0-12-396456-4.00012-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's Disease (AD) is characterized by progressive loss of cognitive function, linked to marked neuronal loss. Pathological hallmarks of the disease are the accumulation of the amyloid-β (Aβ) peptide in the form of amyloid plaques and the intracellular formation of neurofibrillary tangles (NFTs). Accumulating evidence supports a key role for protein phosphorylation in both the normal and pathological actions of Aβ as well as the formation of NFTs. NFTs contain hyperphosphorylated forms of the microtubule-binding protein tau, and phosphorylation of tau by several different kinases leads to its aggregation. The protein kinases involved in the generation and/or actions of tau or Aβ are viable drug targets to prevent or alleviate AD pathology. However, it has also been recognized that the protein phosphatases that reverse the actions of these protein kinases are equally important. Here, we review recent advances in our understanding of serine/threonine and tyrosine protein phosphatases in the pathology of AD.
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Mice lacking phosphatase PP2A subunit PR61/B'delta (Ppp2r5d) develop spatially restricted tauopathy by deregulation of CDK5 and GSK3beta. Proc Natl Acad Sci U S A 2011; 108:6957-62. [PMID: 21482799 DOI: 10.1073/pnas.1018777108] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Functional diversity of protein phosphatase 2A (PP2A) enzymes mainly results from their association with distinct regulatory subunits. To analyze the functions of one such holoenzyme in vivo, we generated mice lacking PR61/B'δ (B56δ), a subunit highly expressed in neural tissues. In PR61/B'δ-null mice the microtubule-associated protein tau becomes progressively phosphorylated at pathological epitopes in restricted brain areas, with marked immunoreactivity for the misfolded MC1-conformation but without neurofibrillary tangle formation. Behavioral tests indicated impaired sensorimotor but normal cognitive functions. These phenotypical characteristics were further underscored in PR61/B'δ-null mice mildly overexpressing human tau. PR61/B'δ-containing PP2A (PP2A(T61δ)) poorly dephosphorylates tau in vitro, arguing against a direct dephosphorylation defect. Rather, the activity of glycogen synthase kinase-3β, a major tau kinase, was found increased, with decreased phosphorylation of Ser-9, a putative cyclin-dependent kinase 5 (CDK5) target. Accordingly, CDK5 activity is decreased, and its cellular activator p35, strikingly absent in the affected brain areas. As opposed to tau, p35 is an excellent PP2A(T61δ) substrate. Our data imply a nonredundant function for PR61/B'δ in phospho-tau homeostasis via an unexpected spatially restricted mechanism preventing p35 hyperphosphorylation and its subsequent degradation.
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Sontag JM, Nunbhakdi-Craig V, Mitterhuber M, Ogris E, Sontag E. Regulation of protein phosphatase 2A methylation by LCMT1 and PME-1 plays a critical role in differentiation of neuroblastoma cells. J Neurochem 2010; 115:1455-65. [PMID: 21044074 DOI: 10.1111/j.1471-4159.2010.07049.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Neuritic alterations are a major feature of many neurodegenerative disorders. Methylation of protein phosphatase 2A (PP2A) catalytic C subunit by the leucine carboxyl methyltransferase (LCMT1), and demethylation by the protein phosphatase methylesterase 1, is a critical PP2A regulatory mechanism. It modulates the formation of PP2A holoenzymes containing the Bα subunit, which dephosphorylate key neuronal cytoskeletal proteins, including tau. Significantly, we have reported that LCMT1, methylated C and Bα expression levels are down-regulated in Alzheimer disease-affected brain regions. In this study, we show that enhanced expression of LCMT1 in cultured N2a neuroblastoma cells, which increases endogenous methylated C and Bα levels, induces changes in F-actin organization. It promotes serum-independent neuritogenesis and development of extended tau-positive processes upon N2a cell differentiation. These stimulatory effects can be abrogated by LCMT1 knockdown and S-adenosylhomocysteine, an inhibitor of methylation reactions. Expression of protein phosphatase methylesterase 1 and the methylation-site L309Δ C subunit mutant, which decrease intracellular methylated C and Bα levels, block N2a cell differentiation and LCMT1-mediated neurite formation. Lastly, inducible and non-inducible knockdown of Bα in N2a cells inhibit process outgrowth. Altogether, our results establish a novel mechanistic link between PP2A methylation and development of neurite-like processes.
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Affiliation(s)
- Jean-Marie Sontag
- School of Biomedical Sciences and Pharmacy, Faculty of Health, The University of Newcastle, Callaghan, NSW, Australia.
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Yang J, Phiel C. Functions of B56-containing PP2As in major developmental and cancer signaling pathways. Life Sci 2010; 87:659-66. [PMID: 20934435 DOI: 10.1016/j.lfs.2010.10.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/08/2010] [Accepted: 09/23/2010] [Indexed: 12/20/2022]
Abstract
Members of the B'/B56/PR61 family regulatory subunits of PP2A determine the subcellular localization, substrate specificity, and catalytic activity of PP2A in a wide range of biological processes. Here, we summarize the structure and intracellular localization of B56-containing PP2As and review functions of B56-containing PP2As in several major developmental/cancer signaling pathways.
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Affiliation(s)
- Jing Yang
- The Research Institute at Nationwide Children's Hospital, Department of Pediatrics, the Ohio State University, 700 Children's Dr., Columbus, OH, 43205, United States.
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Kranias G, Watt LF, Carpenter H, Holst J, Ludowyke R, Strack S, Sim ATR, Verrills NM. Protein phosphatase 2A carboxymethylation and regulatory B subunits differentially regulate mast cell degranulation. Cell Signal 2010; 22:1882-90. [PMID: 20688157 DOI: 10.1016/j.cellsig.2010.07.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 07/14/2010] [Accepted: 07/22/2010] [Indexed: 11/25/2022]
Abstract
Asthma is characterised by antigen-mediated mast cell degranulation resulting in secretion of inflammatory mediators. Protein phosphatase 2A (PP2A) is a serine/threonine protein phosphatase composed of a catalytic (PP2A-C) subunit together with a core scaffold (PP2A-A) subunit and a variable, regulatory (PP2A-B) subunit. Previous studies utilising pharmacological inhibition of protein phosphatases have suggested a positive regulatory role for PP2A in mast cell degranulation. In support of this we find that a high okadaic acid concentration (1μM) inhibits mast cell degranulation. Strikingly, we now show that a low concentration of okadaic acid (0.1μM) has the opposite effect, resulting in enhanced degranulation. Selective downregulation of the PP2A-Cα subunit by short hairpin RNA also enhanced degranulation of RBL-2H3 mast cells, suggesting that the primary role of PP2A is to negatively regulate degranulation. PP2A-B subunits are responsible for substrate specificity, and carboxymethylation of the PP2A-C subunit alters B subunit binding. We show here that carboxymethylation of PP2A-C is dynamically altered during degranulation and inhibition of methylation decreases degranulation. Moreover downregulation of the PP2A-Bα subunit resulted in decreased MK2 phosphorylation and degranulation, whilst downregulation of the PP2A-B'δ subunit enhanced p38 MAPK phosphorylation and degranulation. Taken together these data show that PP2A is both a positive and negative regulator of mast cell degranulation, and this differential role is regulated by carboxymethylation and specific PP2A-B subunit binding.
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Affiliation(s)
- Gregory Kranias
- School of Biomedical Sciences, Faculty of Health, University of Newcastle, Callaghan, NSW 2308, Australia
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Abstract
Protein phosphatase 2A (PP2A) is indispensable in development, and deficits of PP2A and deterioration of neuronal axons have been observed in several neurodegenerative disorders, but the direct link between PP2A and the neuronal axon development is still missing. Here, we show that PP2A is essential for axon development in transfected rat brain and the dissociated hippocampal neurons. Upregulation of PP2A catalytic subunit (PP2Ac) not only promotes formation and elongation of the functional axons but also rescues axon retardation induced by PP2A inhibition. PP2A can dephosphorylate collapsin response mediator protein-2 (CRMP2) that implements the axon polarization, whereas constitutive expression of phosphomimic-CRMP2 abrogates the effect of PP2A upregulation. We also demonstrate that PP2Ac is enriched in the distal axon of the hippocampal neurons. Our results reveal a mechanistic link between PP2A and axonogenesis/axonopathy, suggesting that upregulation of PP2A may be a promising therapeutic for some neurodegenerative disorders.
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Saraf A, Oberg EA, Strack S. Molecular determinants for PP2A substrate specificity: charged residues mediate dephosphorylation of tyrosine hydroxylase by the PP2A/B' regulatory subunit. Biochemistry 2010; 49:986-95. [PMID: 20017541 DOI: 10.1021/bi902160t] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Together with protein phosphatase 1, protein phosphatase 2A (PP2A) contributes the bulk of Ser/Thr phosphatase activity in most cell types. The predominant form of PP2A is a heterotrimer of catalytic (C), scaffolding (A), and diverse regulatory subunits (B, B', and B''). We have previously shown that N-terminal phosphorylation sites in tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, are specifically dephosphorylated by PP2A holoenzymes containing the B'beta regulatory subunit. Here, we identify a Glu residue conserved in B' regulatory subunits that is critical for dephosphorylation and inactivation of tyrosine hydroxylase in vitro and in PC12 cells. According to the PP2A heterotrimer crystal structure, Glu153 (B'beta numbering) abuts the catalytic site on the C subunit, and we demonstrate that Glu153 substitution inhibits multisite TH dephosphorylation without compromising PP2A/B'beta holoenzyme assembly or in vitro dephosphorylation of model substrates. Apart from its role in modulating TH activity, Glu153 is also necessary for PP2A/B'beta-mediated enhancement of nerve growth factor signaling. Furthermore, global phosphoproteome analysis suggests that Glu153 mediates dephosphorylation of most B'beta substrates in PC12 cells. With regard to selectivity determinants in the substrate, we show that B'beta Glu153 recognizes Arg37 and Arg38 in TH to direct dephosphorylation of both upstream (Ser31) and downstream (Ser40) sites. These results provide evidence of a subunit-spanning substrate docking site on the PP2A/B' holoenzyme, in which negatively charged side chains in the regulatory subunit interact with positive charges proximal to phosphorylated residues to mediate site-specific dephosphorylation.
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Affiliation(s)
- Amit Saraf
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA
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Zoubaa S, Konrad R, Piontek G, Schlegel J. Inhibition of NGF-induced neurite outgrowth of rat pheochromocytoma cells (PC12) following administration of dioxyamphetamine. Neurosci Lett 2010; 476:113-8. [PMID: 20138971 DOI: 10.1016/j.neulet.2010.01.070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Revised: 01/12/2010] [Accepted: 01/28/2010] [Indexed: 10/19/2022]
Abstract
Amphetamine analogs are known to induce not only neurotoxicity at serotonergic axon terminals but also neocortical neuronal degeneration. However, a much less studied aspect involves the impact of amphetamine exposure on neuronal development. The present study investigated whether pretreatment of PC12 cells with dioxyamphetamine (DA) alters differentiation of PC12 cells by NGF and, if so, which components of the Ras/Raf/MEK/ERK pathway known to be involved in the differentiation response to NGF are particularly affected. Though exposure of PC12 cells to DA 1h prior to NGF treatment resulted in apopotosis, several PC12 cells survived. However, neurite outgrowth of these NGF-responsive cells was repressed. Immunoblots of whole cell extracts revealed a strong induction rather than inhibition of ERK phosphorylation up to 48h after DA/NGF treatment. Our results indicate that NGF-mediated neurite outgrowth was inhibited by pretreatment with DA, and this blockage of NGF-induced neuritogenesis was not due to an inhibition of ERK phosphorylation.
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Affiliation(s)
- S Zoubaa
- Institute of Pathology, Division of Neuropathology, Technical University, Ismaninger Strasse 22, D-81675 Munich, Germany.
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Kadoyama K, Funakoshi H, Ohya-Shimada W, Nakamura T, Matsumoto K, Matsuyama S, Nakamura T. Disease-dependent reciprocal phosphorylation of serine and tyrosine residues of c-Met/HGF receptor contributes disease retardation of a transgenic mouse model of ALS. Neurosci Res 2009; 65:194-200. [PMID: 19595710 DOI: 10.1016/j.neures.2009.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 06/30/2009] [Accepted: 06/30/2009] [Indexed: 11/19/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by progressive degeneration of motoneurons. We have demonstrated that hepatocyte growth factor (HGF) attenuates loss of both spinal and brainstem motoneurons of ALS model mice expressing mutated human SOD1(G93A) (G93A). This study was designed to assess disease-dependent regulatory mechanisms of c-Met/HGF receptor (c-Met) activation in the facial motoneurons of G93A mice. Using double transgenic mice expressing HGF and mutated SOD1(G93A) (G93A/HGF), we showed that phosphorylation of c-Met tyrosine residues at positions 1230, 1234 and 1235 (phospho-Tyr), and thereby its activation, was slightly evident in G93A and highly obvious in G93A/HGF mice (but absent in WT and HGF-Tg mice). Phosphorylation of the c-Met serine residue at position 985 (phospho-Ser), a residue involved in the negative regulation of its activation, was evident in WT and HGF-Tg mice. Protein phosphatase 2A (PP2A), which is capable of dephosphorylating c-Met phospho-serine, is upregulated in the facial motoneurons of G93A and G93A/HGF mice compared with WT and HGF-Tg mice. Thus, c-Met activation is reciprocally regulated by phosphorylation between c-Met serine and tyrosine residues through PP2A induction in the presence or absence of mutant SOD1 expression, and HGF functions more efficiently in ALS and ALS-related diseases.
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Affiliation(s)
- Keiichi Kadoyama
- Division of Molecular Regenerative Medicine, Department of Biochemistry and Molecular Biology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
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Reece KM, Mazalouskas MD, Wadzinski BE. The Balpha and Bdelta regulatory subunits of PP2A are necessary for assembly of the CaMKIV.PP2A signaling complex. Biochem Biophys Res Commun 2009; 386:582-7. [PMID: 19538941 DOI: 10.1016/j.bbrc.2009.06.062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Accepted: 06/10/2009] [Indexed: 11/16/2022]
Abstract
Calcium/calmodulin-dependent protein kinase IV (CaMKIV) is a serine/threonine kinase that is important in synaptic plasticity and T cell maturation. Activation of CaMKIV requires calcium/calmodulin binding and phosphorylation at T200 by CaMK kinase. Our previous work has shown that protein serine/threonine phosphatase 2A (PP2A) forms a complex with CaMKIV and negatively regulates its activity. Here we demonstrate that PP2A tightly regulates T200 phosphorylation of endogenous CaMKIV, but has little effect on the phosphorylation of the ectopically-expressed kinase. This differential regulation of endogenous versus exogenous CaMKIV is due to differences in their ability to associate with PP2A, as exogenous CaMKIV associates poorly with PP2A in comparison to endogenous CaMKIV. The inability of exogenous CaMKIV to associate with PP2A appears to be due to limiting amounts of endogenous PP2A regulatory B subunits, since coexpression of Balpha or Bdelta causes the recruitment of PP2Ac to ectopic CaMKIV, leading to formation of a CaMKIV.PP2A complex. Together, these data indicate that the B subunits are essential for the interaction of PP2A with CaMKIV.
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Affiliation(s)
- Kelie M Reece
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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