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Ingersoll S, Trouth A, Luo X, Espinoza A, Wen J, Tucker J, Astatike K, Phiel CJ, Kutateladze TG, Wu TP, Ramachandran S, Ren X. Sparse CBX2 nucleates many Polycomb proteins to promote facultative heterochromatinization of Polycomb target genes. bioRxiv 2024:2024.02.05.578969. [PMID: 38370615 PMCID: PMC10871256 DOI: 10.1101/2024.02.05.578969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Facultative heterochromatinization of genomic regulators by Polycomb repressive complex (PRC) 1 and 2 is essential in development and differentiation; however, the underlying molecular mechanisms remain obscure. Using genetic engineering, molecular approaches, and live-cell single-molecule imaging, we quantify the number of proteins within condensates formed through liquid-liquid phase separation (LLPS) and find that in mouse embryonic stem cells (mESCs), approximately 3 CBX2 proteins nucleate many PRC1 and PRC2 subunits to form one non-stoichiometric condensate. We demonstrate that sparse CBX2 prevents Polycomb proteins from migrating to constitutive heterochromatin, demarcates the spatial boundaries of facultative heterochromatin, controls the deposition of H3K27me3, regulates transcription, and impacts cellular differentiation. Furthermore, we show that LLPS of CBX2 is required for the demarcation and deposition of H3K27me3 and is essential for cellular differentiation. Our findings uncover new functional roles of LLPS in the formation of facultative heterochromatin and unravel a new mechanism by which low-abundant proteins nucleate many other proteins to form compartments that enable them to execute their functions.
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Affiliation(s)
- Steven Ingersoll
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Abby Trouth
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Xinlong Luo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Axel Espinoza
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
| | - Joey Wen
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Joseph Tucker
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
| | - Kalkidan Astatike
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Christopher J. Phiel
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
| | - Tatiana G. Kutateladze
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Tao P. Wu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, USA
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
- Department of Integrative Biology, University of Colorado Denver, CO 80217-3364, USA
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2
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Brandt G, Sedivy LJ, Mitchell M, Phiel CJ. Vitamin C and Transferrin Reduce RNA Methylation in Mouse Embryonic Stem Cells. bioRxiv 2023:2023.02.23.529811. [PMID: 36865322 PMCID: PMC9980082 DOI: 10.1101/2023.02.23.529811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Methylation of mRNA on adenosine bases (referred to as m 6 A) is the most common internal modification of mRNA in eukaryotic cells. Recent work has revealed a detailed view of the biological significance of m 6 A-modified mRNA, with a role in mRNA splicing, control of mRNA stability, and mRNA translation efficiency. Importantly, m 6 A is a reversible modification, and the primary enzymes responsible for methylating (Mettl3/Mettl14) and demethylating RNA (FTO/Alkbh5) have been identified. Given this reversibility, we are interested in understanding how m 6 A addition/removal is regulated. Recently, we identified glycogen synthase kinase-3 (Gsk-3) activity as a mediator of m 6 A regulation via controlling the levels of the FTO demethylase in mouse embryonic stem cells (ESCs), with Gsk-3 inhibitors and Gsk-3 knockout both leading to increased FTO protein and decreased m 6 A mRNA levels. To our knowledge, this remains one of the only mechanisms identified for the regulation of m 6 A modifications in ESCs. Several small molecules that have been shown to promote the retention of pluripotency of ESCs, and interestingly, many have connections to the regulation of FTO and m 6 A. Here we show that the combination of Vitamin C and transferrin potently reduces levels of m 6 A and promotes retention of pluripotency in mouse ESCs. Combining Vitamin C and transferrin should prove to be valuable in growing and maintaining pluripotent mouse ESCs.
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3
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Sedivy LJ, Brandt G, Martin AL, Abroe HM, Phiel CJ. Mouse Embryonic Stem Cell Pluripotency Factors Regulate RNA Methylation. bioRxiv 2023:2023.02.23.529801. [PMID: 36865332 PMCID: PMC9980107 DOI: 10.1101/2023.02.23.529801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
The pluripotency of embryonic stem cells (ESCs) is actively promoted by a diverse set of factors, including leukemia inhibitory factor (LIF), glycogen synthase kinase-3 (Gsk-3) and mitogen-activated protein kinase kinase (MEK) inhibitors, ascorbic acid, and α-ketoglutarate. Strikingly, several of these factors intersect with the post-transcriptional methylation of RNA (m 6 A), which has also been shown to play a role in ESC pluripotency. Therefore, we explored the possibility that these factors converge on this biochemical pathway to promote the retention of ESC pluripotency. Mouse ESCs were treated with various combinations of small molecules, and the relative levels of m 6 A RNA were measured, as well as the expression of genes marking naïve and primed ESCs. The most surprising result was the discovery that replacing glucose with high levels of fructose pushed ESCs to a more naïve state and reduced m 6 A RNA abundance. Our results suggest a correlation between molecules previously shown to promote the retention of ESC pluripotency and m 6 A RNA levels, strengthening a molecular connection between reduced m 6 A RNA and the pluripotent state, and provides a foundation for future mechanistic studies on the role of m 6 A and ESC pluripotency.
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Jungers CF, Elliff JM, Masson-Meyers DS, Phiel CJ, Origanti S. Regulation of eukaryotic translation initiation factor 6 dynamics through multisite phosphorylation by GSK3. J Biol Chem 2020; 295:12796-12813. [PMID: 32703900 DOI: 10.1074/jbc.ra120.013324] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 07/16/2020] [Indexed: 01/25/2023] Open
Abstract
Eukaryotic translation initiation factor 6 (eIF6) is essential for the synthesis of 60S ribosomal subunits and for regulating the association of 60S and 40S subunits. A mechanistic understanding of how eIF6 modulates translation in response to stress, specifically starvation-induced stress, is lacking. We here show a novel mode of eIF6 regulation by glycogen synthase kinase 3 (GSK3) that is predominantly active in response to serum starvation. Both GSK3α and GSK3β phosphorylate human eIF6. Multiple residues in the C terminus of eIF6 are phosphorylated by GSK3 in a sequential manner. In response to serum starvation, eIF6 accumulates in the cytoplasm, and this altered localization depends on phosphorylation by GSK3. Disruption of eIF6 phosphorylation exacerbates the translation inhibitory response to serum starvation and stalls cell growth. These results suggest that eIF6 regulation by GSK3 contributes to the attenuation of global protein synthesis that is critical for adaptation to starvation-induced stress.
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Affiliation(s)
- Courtney F Jungers
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | - Jonah M Elliff
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA
| | | | - Christopher J Phiel
- Department of Integrative Biology, University of Colorado Denver, Colorado, USA
| | - Sofia Origanti
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, USA .,Department of Biology, Saint Louis University, St. Louis, Missouri, USA
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5
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Asherin RM, Everhart KD, Stophaeros SL, Vogeli JM, Fowler J, Phiel CJ, Kaplan PS. Associations between maternal depression and mother and infant oxytocin receptor gene (OXTR_rs53576) polymorphisms. Dev Psychobiol 2019; 62:496-504. [DOI: 10.1002/dev.21938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/02/2019] [Accepted: 10/20/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Ryan M. Asherin
- Department of Psychology University of Colorado Denver Denver CO USA
| | - Kevin D. Everhart
- Department of Psychology University of Colorado Denver Denver CO USA
| | | | - Jo M. Vogeli
- Department of Anesthesiology Anschutz Medical Campus School of Medicine University of Colorado Denver Denver CO USA
| | - Joshua Fowler
- Department of Psychology University of Colorado Denver Denver CO USA
| | | | - Peter S. Kaplan
- Department of Psychology University of Colorado Denver Denver CO USA
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6
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Nakamura M, Liu T, Husain S, Zhai P, Warren JS, Hsu CP, Matsuda T, Phiel CJ, Cox JE, Tian B, Li H, Sadoshima J. Glycogen Synthase Kinase-3α Promotes Fatty Acid Uptake and Lipotoxic Cardiomyopathy. Cell Metab 2019; 29:1119-1134.e12. [PMID: 30745182 PMCID: PMC6677269 DOI: 10.1016/j.cmet.2019.01.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 11/27/2018] [Accepted: 01/10/2019] [Indexed: 02/06/2023]
Abstract
Obesity induces lipotoxic cardiomyopathy, a condition in which lipid accumulation in cardiomyocytes causes cardiac dysfunction. Here, we show that glycogen synthase kinase-3α (GSK-3α) mediates lipid accumulation in the heart. Fatty acids (FAs) upregulate GSK-3α, which phosphorylates PPARα at Ser280 in the ligand-binding domain (LBD). This modification ligand independently enhances transcription of a subset of PPARα targets, selectively stimulating FA uptake and storage, but not oxidation, thereby promoting lipid accumulation. Constitutively active GSK-3α, but not GSK-3β, was sufficient to drive PPARα signaling, while cardiac-specific knockdown of GSK-3α, but not GSK-3β, or replacement of PPARα Ser280 with Ala conferred resistance to lipotoxicity in the heart. Fibrates, PPARα ligands, inhibited phosphorylation of PPARα at Ser280 by inhibiting the interaction of GSK-3α with the LBD of PPARα, thereby reversing lipotoxic cardiomyopathy. These results suggest that GSK-3α promotes lipid anabolism through PPARα-Ser280 phosphorylation, which underlies the development of lipotoxic cardiomyopathy in the context of obesity.
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Affiliation(s)
- Michinari Nakamura
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Tong Liu
- Center for Advanced Proteomics Research, Department of Biochemistry & Molecular Biology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Seema Husain
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Peiyong Zhai
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Junco S Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute and Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Chiao-Po Hsu
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taipei City, Taiwan
| | - Takahisa Matsuda
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Christopher J Phiel
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - James E Cox
- Metabolomics Core Research Facility and Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Bin Tian
- Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Hong Li
- Center for Advanced Proteomics Research, Department of Biochemistry & Molecular Biology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA.
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7
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Faulds KJ, Egelston JN, Sedivy LJ, Mitchell MK, Garimella S, Kozlowski H, D'Alessandro A, Hansen KC, Balsbaugh JL, Phiel CJ. Glycogen synthase kinase-3 (GSK-3) activity regulates mRNA methylation in mouse embryonic stem cells. J Biol Chem 2018; 293:10731-10743. [PMID: 29777057 DOI: 10.1074/jbc.ra117.001298] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/09/2018] [Indexed: 12/22/2022] Open
Abstract
Glycogen synthase kinase-3 (GSK-3) activity regulates multiple signal transduction pathways and is also a key component of the network responsible for maintaining stem cell pluripotency. Genetic deletion of Gsk-3α and Gsk-3β or inhibition of GSK-3 activity via small molecules promotes stem cell pluripotency, yet the mechanism underlying the role for GSK-3 in this process remains ambiguous. Another cellular process that has been shown to affect stem cell pluripotency is mRNA methylation (m6A). Here, we describe an intersection between these components, the regulation of m6A by GSK-3. We find that protein levels for the RNA demethylase, FTO (fat mass and obesity-associated protein), are elevated in Gsk-3α;Gsk-3β-deficient mouse embryonic stem cells (ESCs). FTO is normally phosphorylated by GSK-3, and MS identified the sites on FTO that are phosphorylated in a GSK-3-dependent fashion. GSK-3 phosphorylation of FTO leads to polyubiquitination, but in Gsk-3 knockout ESCs, that process is impaired, resulting in elevated levels of FTO protein. As a consequence of altered FTO protein levels, mRNAs in Gsk-3 knockout ESCs have 50% less m6A than WT ESCs, and m6A-Seq analysis reveals the specific mRNAs that have reduced m6A modifications. Taken together, we provide the first evidence for how m6A demethylation is regulated in mammalian cells and identify a putative novel mechanism by which GSK-3 activity regulates stem cell pluripotency.
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Affiliation(s)
- Kelsie J Faulds
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204
| | - Jennifer N Egelston
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204
| | - Laura J Sedivy
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204
| | - Matthew K Mitchell
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204
| | - Sanjana Garimella
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204
| | - Hanna Kozlowski
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204
| | - Angelo D'Alessandro
- the Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, Colorado 80045, and
| | - Kirk C Hansen
- the Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, Colorado 80045, and
| | - Jeremy L Balsbaugh
- the Mass Spectrometry Core Facility, Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado 80309
| | - Christopher J Phiel
- From the Department of Integrative Biology, University of Colorado Denver, Denver, Colorado 80204,
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8
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Gonzalez Malagon SG, Lopez Muñoz AM, Doro D, Bolger TG, Poon E, Tucker ER, Adel Al-Lami H, Krause M, Phiel CJ, Chesler L, Liu KJ. Glycogen synthase kinase 3 controls migration of the neural crest lineage in mouse and Xenopus. Nat Commun 2018; 9:1126. [PMID: 29555900 PMCID: PMC5859133 DOI: 10.1038/s41467-018-03512-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 02/20/2018] [Indexed: 12/12/2022] Open
Abstract
Neural crest migration is critical to its physiological function. Mechanisms controlling mammalian neural crest migration are comparatively unknown, due to difficulties accessing this cell population in vivo. Here we report requirements of glycogen synthase kinase 3 (GSK3) in regulating the neural crest in Xenopus and mouse models. We demonstrate that GSK3 is tyrosine phosphorylated (pY) in mouse neural crest cells and that loss of GSK3 leads to increased pFAK and misregulation of Rac1 and lamellipodin, key regulators of cell migration. Genetic reduction of GSK3 results in failure of migration. We find that pY-GSK3 phosphorylation depends on anaplastic lymphoma kinase (ALK), a protein associated with neuroblastoma. Consistent with this, neuroblastoma cells with increased ALK activity express high levels of pY-GSK3, and blockade of GSK3 or ALK can affect migration of these cells. Altogether, this work identifies a role for GSK3 in cell migration during neural crest development and cancer. Defects in neural crest development cause neurocristopathies and cancer, but what regulates this is unclear. Here, the authors show that glycogen synthase kinase 3 (GSK3) regulates migration of neural crest cells, as shown on genetic deletion of GSK3 in the mouse, and that this acts via anaplastic lymphoma kinase.
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Affiliation(s)
| | - Anna M Lopez Muñoz
- Centre for Craniofacial and Regenerative Biology, King's College London, London, SE1 9RT, UK
| | - Daniel Doro
- Centre for Craniofacial and Regenerative Biology, King's College London, London, SE1 9RT, UK
| | - Triòna G Bolger
- Centre for Craniofacial and Regenerative Biology, King's College London, London, SE1 9RT, UK
| | - Evon Poon
- Paediatric Solid Tumour Biology, Institute of Cancer Research/Royal Marsden NHS Trust, Surrey, SM2 5NG, UK
| | - Elizabeth R Tucker
- Paediatric Solid Tumour Biology, Institute of Cancer Research/Royal Marsden NHS Trust, Surrey, SM2 5NG, UK
| | - Hadeel Adel Al-Lami
- Centre for Craniofacial and Regenerative Biology, King's College London, London, SE1 9RT, UK
| | - Matthias Krause
- Randall Division of Cell & Molecular Biophysics, King's College London, London, SE1 1UL, UK
| | - Christopher J Phiel
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, 80204, USA
| | - Louis Chesler
- Paediatric Solid Tumour Biology, Institute of Cancer Research/Royal Marsden NHS Trust, Surrey, SM2 5NG, UK
| | - Karen J Liu
- Centre for Craniofacial and Regenerative Biology, King's College London, London, SE1 9RT, UK.
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Meredith GD, D'Ippolito A, Dudas M, Zeidner LC, Hostetter L, Faulds K, Arnold TH, Popkie AP, Doble BW, Marnellos G, Adams C, Wang Y, Phiel CJ. Glycogen synthase kinase-3 (Gsk-3) plays a fundamental role in maintaining DNA methylation at imprinted loci in mouse embryonic stem cells. Mol Biol Cell 2015; 26:2139-50. [PMID: 25833708 PMCID: PMC4472022 DOI: 10.1091/mbc.e15-01-0013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/25/2015] [Indexed: 12/15/2022] Open
Abstract
A genome-wide analysis is given of DNA methylation in mouse embryonic stem cells in which both Gsk-3α and Gsk-3β have been genetically deleted. DNA methylation patterns are compared to those of wild-type cells. More than 75% of known imprinted loci have reduced DNA methylation in the Gsk-3–knockout cells. Glycogen synthase kinase-3 (Gsk-3) is a key regulator of multiple signal transduction pathways. Recently we described a novel role for Gsk-3 in the regulation of DNA methylation at imprinted loci in mouse embryonic stem cells (ESCs), suggesting that epigenetic changes regulated by Gsk-3 are likely an unrecognized facet of Gsk-3 signaling. Here we extend our initial observation to the entire mouse genome by enriching for methylated DNA with the MethylMiner kit and performing next-generation sequencing (MBD-Seq) in wild-type and Gsk-3α−/−;Gsk-3β−/− ESCs. Consistent with our previous data, we found that 77% of known imprinted loci have reduced DNA methylation in Gsk-3-deficient ESCs. More specifically, we unambiguously identified changes in DNA methylation within regions that have been confirmed to function as imprinting control regions. In many cases, the reduced DNA methylation at imprinted loci in Gsk-3α−/−;Gsk-3β−/− ESCs was accompanied by changes in gene expression as well. Furthermore, many of the Gsk-3–dependent, differentially methylated regions (DMRs) are identical to the DMRs recently identified in uniparental ESCs. Our data demonstrate the importance of Gsk-3 activity in the maintenance of DNA methylation at a majority of the imprinted loci in ESCs and emphasize the importance of Gsk-3–mediated signal transduction in the epigenome.
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Affiliation(s)
| | - Anthony D'Ippolito
- Thermo Fisher Scientific, Carlsbad, CA 92008 Center for Human and Molecular Genetics, Nationwide Children's Hospital, Columbus, OH 43205
| | | | - Leigh C Zeidner
- Center for Human and Molecular Genetics, Nationwide Children's Hospital, Columbus, OH 43205
| | - Logan Hostetter
- Department of Integrative Biology, University of Colorado Denver, Denver, CO 80204
| | - Kelsie Faulds
- Department of Integrative Biology, University of Colorado Denver, Denver, CO 80204
| | - Thomas H Arnold
- Department of Integrative Biology, University of Colorado Denver, Denver, CO 80204
| | - Anthony P Popkie
- Graduate Program in Molecular, Cellular and Developmental Biology, Ohio State University, Columbus, OH 43210
| | - Bradley W Doble
- McMaster Stem Cell and Cancer Research Institute, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | | | | | - Yulei Wang
- Thermo Fisher Scientific, Foster City, CA 94404
| | - Christopher J Phiel
- Center for Human and Molecular Genetics, Nationwide Children's Hospital, Columbus, OH 43205 Department of Integrative Biology, University of Colorado Denver, Denver, CO 80204
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10
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Bhattacharjee R, Goswami S, Dudiki T, Popkie AP, Phiel CJ, Kline D, Vijayaraghavan S. Targeted disruption of glycogen synthase kinase 3A (GSK3A) in mice affects sperm motility resulting in male infertility. Biol Reprod 2015; 92:65. [PMID: 25568307 DOI: 10.1095/biolreprod.114.124495] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The signaling enzyme glycogen synthase kinase 3 (GSK3) exists as two isoforms-GSK3A and GSK3B. Protein phosphorylation by GSK3 has important signaling roles in several cells. In our past work, we found that both isoforms of GSK3 are present in mouse sperm and that catalytic GSK3 activity correlates with motility of sperm from several species. Here, we examined the role of Gsk3a in male fertility using a targeted gene knockout (KO) approach. The mutant mice are viable, but have a male infertility phenotype, while female fertility is unaffected. Testis weights of Gsk3a(-/-) mice are normal and sperm are produced in normal numbers. Although spermatogenesis is apparently unimpaired, sperm motility parameters in vitro are impaired. In addition, the flagellar waveform appears abnormal, characterized by low amplitude of flagellar beat. Sperm ATP levels were lower in Gsk3a(-/-) mice compared to wild-type animals. Protein phosphatase PP1 gamma2 protein levels were unaltered, but its catalytic activity was elevated in KO sperm. Remarkably, tyrosine phosphorylation of hexokinase and capacitation-associated changes in tyrosine phosphorylation of proteins are absent or significantly lower in Gsk3a(-/-) sperm. The GSK3B isoform was present and unaltered in testis and sperm of Gsk3a(-/-) mice, showing the inability of GSK3B to substitute for GSK3A in this context. Our studies show that sperm GSK3A is essential for male fertility. In addition, the GSK3A isoform, with its highly conserved glycine-rich N terminus in mammals, may have an isoform-specific role in its requirement for normal sperm motility and fertility.
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Affiliation(s)
| | - Suranjana Goswami
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Tejasvi Dudiki
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Anthony P Popkie
- Laboratory of Cancer Epigenomics, Center for Epigenetics, Van Andel Research Institute, Grand Rapids, Michigan
| | - Christopher J Phiel
- Department of Integrative Biology, University of Colorado Denver, Denver, Colorado
| | - Douglas Kline
- Department of Biological Sciences, Kent State University, Kent, Ohio
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11
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Zhen CY, Duc HN, Kokotovic M, Phiel CJ, Ren X. Cbx2 stably associates with mitotic chromosomes via a PRC2- or PRC1-independent mechanism and is needed for recruiting PRC1 complex to mitotic chromosomes. Mol Biol Cell 2014; 25:3726-39. [PMID: 25232004 PMCID: PMC4230780 DOI: 10.1091/mbc.e14-06-1109] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Cbx2 is immobilized at mitotic chromosomes, and the immobilization is independent of PRC1 or PRC2. Cbx2 plays important roles in recruiting PRC1 complex to mitotic chromosomes. This study provides novel insights into the PcG epigenetic memory passing down through cell divisions. Polycomb group (PcG) proteins are epigenetic transcriptional factors that repress key developmental regulators and maintain cellular identity through mitosis via a poorly understood mechanism. Using quantitative live-cell imaging in mouse ES cells and tumor cells, we demonstrate that, although Polycomb repressive complex (PRC) 1 proteins (Cbx-family proteins, Ring1b, Mel18, and Phc1) exhibit variable capacities of association with mitotic chromosomes, Cbx2 overwhelmingly binds to mitotic chromosomes. The recruitment of Cbx2 to mitotic chromosomes is independent of PRC1 or PRC2, and Cbx2 is needed to recruit PRC1 complex to mitotic chromosomes. Quantitative fluorescence recovery after photobleaching analysis indicates that PRC1 proteins rapidly exchange at interphasic chromatin. On entry into mitosis, Cbx2, Ring1b, Mel18, and Phc1 proteins become immobilized at mitotic chromosomes, whereas other Cbx-family proteins dynamically bind to mitotic chromosomes. Depletion of PRC1 or PRC2 protein has no effect on the immobilization of Cbx2 on mitotic chromosomes. We find that the N-terminus of Cbx2 is needed for its recruitment to mitotic chromosomes, whereas the C-terminus is required for its immobilization. Thus these results provide fundamental insights into the molecular mechanisms of epigenetic inheritance.
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Affiliation(s)
- Chao Yu Zhen
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364
| | - Huy Nguyen Duc
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364
| | - Marko Kokotovic
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364
| | - Christopher J Phiel
- Department of Integrative Biology, University of Colorado Denver, Denver, CO 80217-3364
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364
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12
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Bartman CM, Egelston J, Ren X, Das R, Phiel CJ. A simple and efficient method for transfecting mouse embryonic stem cells using polyethylenimine. Exp Cell Res 2014; 330:178-85. [PMID: 25102378 DOI: 10.1016/j.yexcr.2014.07.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 07/12/2014] [Accepted: 07/15/2014] [Indexed: 12/24/2022]
Abstract
Mouse embryonic stem cells (ESCs) can be transfected by electroporation, liposomal reagents, and viral transduction methods. The cationic polymer polyethylenimine (PEI) has been shown to transfect a variety of differentiated mammalian cell types, including mouse ESCs, but existing methods require the use of additional equipment that is not readily accessible to most labs. Here we describe conditions that permit for the efficient transfection of mouse ESCs with low cytotoxicity and without the need for specialized equipment. Our goal was to devise a protocol for the PEI-mediated transfection of mouse ESCs that was comparable in ease to commercial transfection reagents. For these studies, we compared PEI transfection efficiency and cytotoxicity to a well-known liposomal transfection reagent, Lipofectamine2000(™) (LF2K), using fluorescence microscopy, flow cytometry, cell viability assays, and Western blotting. We provide evidence that PEI transfection of mouse ESCs compares favorably to LF2K. Our optimized protocol for efficient transfection of mouse ESCs with PEI is detailed in this report.
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Affiliation(s)
- Colleen M Bartman
- Department of Integrative Biology, University of Colorado Denver, S4111, 1201 Fifth Street, Denver, CO 80204, United States
| | - Jennifer Egelston
- Department of Integrative Biology, University of Colorado Denver, S4111, 1201 Fifth Street, Denver, CO 80204, United States
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, 1201 Fifth Street, Denver, CO 80204, United States
| | - Raibatak Das
- Department of Integrative Biology, University of Colorado Denver, S4111, 1201 Fifth Street, Denver, CO 80204, United States
| | - Christopher J Phiel
- Department of Integrative Biology, University of Colorado Denver, S4111, 1201 Fifth Street, Denver, CO 80204, United States.
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13
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Bartman CM, Egelston J, Kattula S, Zeidner LC, D’Ippolito A, Doble BW, Phiel CJ. Gene Expression Profiling in Mouse Embryonic Stem Cells Reveals Glycogen Synthase Kinase-3-Dependent Targets of Phosphatidylinositol 3-Kinase and Wnt/β-Catenin Signaling Pathways. Front Endocrinol (Lausanne) 2014; 5:133. [PMID: 25165462 PMCID: PMC4131280 DOI: 10.3389/fendo.2014.00133] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 07/28/2014] [Indexed: 11/13/2022] Open
Abstract
Glycogen synthase kinase-3 (Gsk-3) activity is an important regulator of numerous signal transduction pathways. Gsk-3 activity is the sum of two largely redundant proteins, Gsk-3α and Gsk-3β, and in general, Gsk-3 is a negative regulator of cellular signaling. Genetic deletion of both Gsk-3α and Gsk-3β in mouse embryonic stem cells (ESCs) has previously been shown to lead to the constitutive activation of the Wnt/β-catenin signaling pathway. However, in addition to Wnt signaling, all Gsk-3-regulated pathways, such as insulin signaling, are also affected simultaneously in Gsk-3α(-) (/) (-); Gsk-3β(-) (/) (-)ESCs. In an effort to better understand how specific signaling pathways contribute to the global pattern of gene expression in Gsk-3α(-) (/) (-); Gsk-3β(-) (/) (-)ESCs, we compared the gene expression profiles in Gsk-3α(-) (/) (-); Gsk-3β(-) (/) (-) ESCs to mouse ESCs in which either Wnt/β-catenin signaling or phosphatidylinositol 3-kinase (PI3K)-dependent insulin signaling are constitutively active. Our results show that Wnt signaling has a greater effect on up-regulated genes in the Gsk-3α(-) (/) (-); Gsk-3β(-) (/) (-)ESCs, whereas PI3K-dependent insulin signaling is more responsible for the down-regulation of genes in the same cells. These data show the importance of Gsk-3 activity on gene expression in mouse ESCs, and that these effects are due to the combined effects of multiple signaling pathways.
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Affiliation(s)
- Colleen M. Bartman
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Jennifer Egelston
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Sravya Kattula
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
| | - Leigh C. Zeidner
- Center for Human and Molecular Genetics, Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA
| | - Anthony D’Ippolito
- Center for Human and Molecular Genetics, Research Institute at Nationwide Children’s Hospital, Columbus, OH, USA
| | - Bradley W. Doble
- Stem Cell and Cancer Research Institute, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Christopher J. Phiel
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, USA
- *Correspondence: Christopher J. Phiel, Department of Integrative Biology, University of Colorado Denver, Campus Box 171, P.O. Box 173364, Denver, CO 80217-3364, USA e-mail:
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14
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Fleming JL, Phiel CJ, Toland AE. The role for oxidative stress in aberrant DNA methylation in Alzheimer's disease. Curr Alzheimer Res 2013; 9:1077-96. [PMID: 21605062 DOI: 10.2174/156720512803569000] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Revised: 05/20/2011] [Accepted: 05/25/2011] [Indexed: 11/22/2022]
Abstract
Alzheimer's disease (AD) is a common, progressive neurodegenerative disorder without highly effective therapies. The etiology of AD is heterogeneous with amyloid-beta plaques, neurofibrillary tangles, oxidative stress, and aberrant DNA methylation all implicated in the disease pathogenesis. DNA methylation is a well-established process for regulating gene expression and has been found to regulate a growing number of important genes involved in AD development and progression. Additionally, aberrations in one-carbon metabolism are a common finding in AD patients with individuals exhibiting low S-adenosylmethionine and high homocysteine levels as well as low folate and vitamin B. Oxidative stress is considered one of the earliest events in AD pathogenesis and is thought to contribute largely to neuronal cell death. Emerging evidence suggests an interaction exists between oxidative stress and DNA methylation; however, the mechanism(s) remain unclear. This review summarizes known and potential genes implicated in AD that are regulated by DNA methylation and oxidative stress. We also highlight the evidence for the role of oxidative damage contributing to DNA hypomethylation in AD patients through several mechanisms as well as implications for disease understanding and therapeutic development.
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Affiliation(s)
- Jessica L Fleming
- Department of Molecular Virology, Immunology and Medical Genetics, Comprehensive Cancer Center, Columbus, OH 43210, USA
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15
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16
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Zeidner LC, Buescher JL, Phiel CJ. A novel interaction between Glycogen Synthase Kinase-3α (GSK-3α) and the scaffold protein Receptor for Activated C-Kinase 1 (RACK1) regulates the circadian clock. Int J Biochem Mol Biol 2011; 2:318-327. [PMID: 22187666 PMCID: PMC3242428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 10/08/2011] [Accepted: 10/13/2011] [Indexed: 05/31/2023]
Abstract
Glycogen synthase kinase-3α (GSK-3α) and GSK-3β are intracellular kinases with largely redundant functions. However, the deletion of each GSK-3 isoform in the mouse has distinct consequences, suggesting that these related enzymes also have non-overlapping isoform-specific functions. A yeast two-hybrid screen for GSK-3α interacting partners revealed an interaction with the Receptor for Activated C-Kinase 1 (RACK1). We confirm this interaction in mammalian cells, and provide evidence that RACK1 does not interact with GSK-3β. Structure-function analyses revealed that WD repeats 5-6 are required to interact with GSK-3α. Furthermore, this interaction is independent of GSK-3α activity. Finally, our data show that the GSK-3α-RACK1 interaction is necessary for regulating the circadian clock in mammalian cells. In summary, our data provides a mechanistic link between GSK-3 and RACK-1 in the regulation of the circadian clock, and demonstrates that this effect is specific to the GSK-3α isoform.
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Affiliation(s)
- Leigh C Zeidner
- Center for Molecular and Human GeneticsThe Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205
| | - Jessica L Buescher
- Integrated Biomedical Science Graduate ProgramCollege of Medicine, The Ohio State University, 333 West 10 Avenue, Columbus, OH 43210USA
| | - Christopher J Phiel
- Center for Molecular and Human GeneticsThe Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205
- Integrated Biomedical Science Graduate ProgramCollege of Medicine, The Ohio State University, 333 West 10 Avenue, Columbus, OH 43210USA
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17
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Abstract
In Wnt/β-catenin signaling pathway, Gsk3β functions to facilitate β-catenin degradation. Inactivation of Gsk3β in mice causes a cleft palate formation, suggesting an involvement of Wnt/β-catenin signaling during palatogenesis. In this study, we have investigated the expression pattern, tissue-specific requirement and function of Gsk3β during mouse palatogenesis. We showed that Gsk3β is primarily expressed in the palatal epithelium, particularly in the medial edge epithelium overlapping with β-catenin. Tissue-specific gene inactivation studies demonstrated an essential role for Gsk3β in the epithelium for palate elevation, and disruption of which contributes to cleft palate phenotype in Gsk3β mutant. We observed that expression of Aixn2, a direct target gene of Wnt/β-catenin signaling, is ectopically activated in the mutant tongue, but not in the palate. Our results indicate that Gsk3β is an intrinsic regulator required in the epithelium for palate elevation, and could act through a pathway independent of Wnt/β-catenin signaling to regulate palate development.
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Affiliation(s)
- Fenglei He
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118, USA
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18
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Popkie AP, Zeidner LC, Albrecht AM, D'Ippolito A, Eckardt S, Newsom DE, Groden J, Doble BW, Aronow B, McLaughlin KJ, White P, Phiel CJ. Phosphatidylinositol 3-kinase (PI3K) signaling via glycogen synthase kinase-3 (Gsk-3) regulates DNA methylation of imprinted loci. J Biol Chem 2010; 285:41337-47. [PMID: 21047779 DOI: 10.1074/jbc.m110.170704] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Glycogen synthase kinase-3 (Gsk-3) isoforms, Gsk-3α and Gsk-3β, are constitutively active, largely inhibitory kinases involved in signal transduction. Underscoring their biological significance, altered Gsk-3 activity has been implicated in diabetes, Alzheimer disease, schizophrenia, and bipolar disorder. Here, we demonstrate that deletion of both Gsk-3α and Gsk-3β in mouse embryonic stem cells results in reduced expression of the de novo DNA methyltransferase Dnmt3a2, causing misexpression of the imprinted genes Igf2, H19, and Igf2r and hypomethylation of their corresponding imprinted control regions. Treatment of wild-type embryonic stem cells and neural stem cells with the Gsk-3 inhibitor, lithium, phenocopies the DNA hypomethylation at these imprinted loci. We show that inhibition of Gsk-3 by phosphatidylinositol 3-kinase (PI3K)-mediated activation of Akt also results in reduced DNA methylation at these imprinted loci. Finally, we find that N-Myc is a potent Gsk-3-dependent regulator of Dnmt3a2 expression. In summary, we have identified a signal transduction pathway that is capable of altering the DNA methylation of imprinted loci.
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Affiliation(s)
- Anthony P Popkie
- Graduate Program in Molecular, Cellular and Developmental Biology, The Ohio State University, Columbus, Ohio 43210, USA
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19
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Phiel CJ. P2‐310: A novel Gsk‐3‐dependent mechanism regulates DNA methylation of imprinted genes. Alzheimers Dement 2010. [DOI: 10.1016/j.jalz.2010.05.1361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Abstract
Glycogen synthase kinase-3 (GSK-3) isoforms, GSK-3alpha and GSK-3beta, are serine/threonine kinases involved in numerous cellular processes and diverse diseases, including Alzheimer disease, cancer, and diabetes. GSK-3 isoforms function redundantly in some settings, while, in others, they exhibit distinct activities. Despite intensive investigation into the physiological roles of GSK-3 isoforms, the basis for their differential activities remains unresolved. A more comprehensive understanding of the mechanistic basis for GSK-3 isoform-specific functions could lead to the development of isoform-specific inhibitors. Here, we describe a structure-function analysis of GSK-3alpha and GSK-3beta in mammalian cells. We deleted the noncatalytic N and C termini in both GSK-3 isoforms and generated point mutations of key regulatory residues. We examined the effect of these mutations on GSK-3 activity toward Tau, activity in Wnt signaling, interaction with Axin, and GSK-3alpha/beta Tyr(279/216) phosphorylation. We found that the N termini of both GSK-3 isoforms were dispensable, whereas progressive C-terminal deletions resulted in protein misfolding exhibited by deficient activity, impaired ability to interact with Axin, and a loss of Tyr(279/216) phosphorylation. Our data predict that small molecules targeting the divergent C terminus may lead to isoform-specific GSK-3 inhibition through destabilization of the GSK-3 structure.
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Affiliation(s)
- Jessica L Buescher
- Integrated Biomedical Science Graduate Program, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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21
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Popkie A, Buescher JL, Miranda CJ, Kaspar BK, Phiel CJ, Doble BW. O1‐03–02: Analyzing the endogenous roles of GSK‐3 isoforms in APP processing in GSK‐3 deficient cells. Alzheimers Dement 2008. [DOI: 10.1016/j.jalz.2008.05.230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Anthony Popkie
- The Research Institute at Nationwide Children's HospitalcolumbusOHUSA
| | | | - Carlos J. Miranda
- The Research Institute at Nationwide Children's HospitalcolumbusOHUSA
| | - Brian K. Kaspar
- The Research Institute at Nationwide Children's HospitalcolumbusOHUSA
| | | | - Bradley W. Doble
- Samuel Lunenfeld Research Institute ,Mount Sinai HospitalTorontoONCanada
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22
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Buescher JL, Phiel CJ. P3‐321: The carboxyl termini of GSK‐3 isoforms are essential for activity. Alzheimers Dement 2008. [DOI: 10.1016/j.jalz.2008.05.1890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
| | - Christopher J. Phiel
- The Ohio State UniversityColumbusOHUSA
- The Research Institute at Nationwide Children's HospitalColumbusOHUSA
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23
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Phiel CJ, Buescher J. P4-195 A role for GSK-3A in the trafficking of APP C-terminal fragments. Neurobiol Aging 2004. [DOI: 10.1016/s0197-4580(04)81753-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Petit A, Pasini A, Alves Da Costa C, Ayral E, Hernandez JF, Dumanchin-Njock C, Phiel CJ, Marambaud P, Wilk S, Farzan M, Fulcrand P, Martinez J, Andrau D, Checler F. JLK isocoumarin inhibitors: Selective ?-secretase inhibitors that do not interfere with notch pathway in vitro or in vivo. J Neurosci Res 2003; 74:370-7. [PMID: 14598313 DOI: 10.1002/jnr.10747] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
gamma-Secretase activity is involved in the generation of Abeta and therefore likely contributes to the pathology of Alzheimer's disease. Blocking this activity was seen as a major therapeutic target to slow down or arrest Abeta-related AD progression. This strategy seemed more doubtful when it was established that gamma-secretase also targets other substrates including Notch, a particularly important transmembrane protein involved in vital functions, at both embryonic and adulthood stages. We have described previously new non-peptidic inhibitors able to selectively inhibit Abeta cellular production in vitro without altering Notch pathway. We show here that in vivo, these inhibitors do not alter the Notch pathway responsible for somitogenesis in the zebrafish embryo. In addition, we document further the selectivity of JLK inhibitors by showing that, unlike other described gamma-secretase inhibitors, these agents do not affect E-cadherin processing. Finally, we establish that JLKs do not inhibit beta-site APP cleaving enzymes (BACE) 1 and BACE2, alpha-secretase, the proteasome, and GSK3beta kinase. Altogether, JLK inhibitors are the sole agents to date that are able to prevent Abeta production without triggering unwanted cleavages of other proteins.
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Affiliation(s)
- A Petit
- Institut de Pharmacologie, Moléculaire et Cellulaire, CNRS, UMR6097, Valbonne, France
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25
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Zhang F, Phiel CJ, Spece L, Gurvich N, Klein PS. Inhibitory phosphorylation of glycogen synthase kinase-3 (GSK-3) in response to lithium. Evidence for autoregulation of GSK-3. J Biol Chem 2003; 278:33067-77. [PMID: 12796505 DOI: 10.1074/jbc.m212635200] [Citation(s) in RCA: 344] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycogen synthase kinase-3 (GSK-3) is a critical, negative regulator of diverse signaling pathways. Lithium is a direct inhibitor of GSK-3 and has been widely used to test the putative role of GSK-3 in multiple settings. However, lithium also inhibits other targets, including inositol monophosphatase and structurally related phosphomonoesterases, and thus additional approaches are needed to attribute a given biological effect of lithium to a specific target. For example, lithium is known to increase the inhibitory N-terminal phosphorylation of GSK-3, but the target of lithium responsible for this indirect regulation has not been identified. We have characterized a short peptide derived from the GSK-3 interaction domain of Axin that potently inhibits GSK-3 activity in vitro and in mammalian cells and robustly activates Wnt-dependent transcription, mimicking lithium action. We show here, using the GSK-3 interaction domain peptide, as well as small molecule inhibitors of GSK-3, that lithium induces GSK-3 N-terminal phosphorylation through direct inhibition of GSK-3 itself. Reduction of GSK-3 protein levels, either by RNA interference or by disruption of the mouse GSK-3beta gene, causes increased N-terminal phosphorylation of GSK-3, confirming that GSK-3 regulates its own phosphorylation status. Finally, evidence is presented that N-terminal phosphorylation of GSK-3 can be regulated by the GSK-3-dependent protein phosphatase-1.inhibitor-2 complex.
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MESH Headings
- 3T3 Cells
- Animals
- Cell Line
- Cell Nucleus/metabolism
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Cytoplasm/metabolism
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Enzymologic
- Genes, Reporter
- Glycogen Synthase Kinase 3/chemistry
- Glycogen Synthase Kinase 3/metabolism
- Humans
- Immunoblotting
- Inhibitory Concentration 50
- Lithium/pharmacology
- Mice
- Microscopy, Fluorescence
- Models, Biological
- Peptides/chemistry
- Phosphoprotein Phosphatases/metabolism
- Phosphorylation
- Plasmids/metabolism
- Protein Binding
- Protein Phosphatase 1
- Protein Structure, Tertiary
- RNA Interference
- Recombinant Proteins/metabolism
- Ribosomal Protein S6 Kinases, 70-kDa/metabolism
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Serine/chemistry
- Transcription, Genetic
- Transfection
- Tumor Cells, Cultured
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Affiliation(s)
- Fang Zhang
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148, USA
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26
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Phiel CJ, Wilson CA, Lee VMY, Klein PS. GSK-3alpha regulates production of Alzheimer's disease amyloid-beta peptides. Nature 2003; 423:435-9. [PMID: 12761548 DOI: 10.1038/nature01640] [Citation(s) in RCA: 882] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Accepted: 04/01/2003] [Indexed: 11/08/2022]
Abstract
Alzheimer's disease is associated with increased production and aggregation of amyloid-beta (Abeta) peptides. Abeta peptides are derived from the amyloid precursor protein (APP) by sequential proteolysis, catalysed by the aspartyl protease BACE, followed by presenilin-dependent gamma-secretase cleavage. Presenilin interacts with nicastrin, APH-1 and PEN-2 (ref. 6), all of which are required for gamma-secretase function. Presenilins also interact with alpha-catenin, beta-catenin and glycogen synthase kinase-3beta (GSK-3beta), but a functional role for these proteins in gamma-secretase activity has not been established. Here we show that therapeutic concentrations of lithium, a GSK-3 inhibitor, block the production of Abeta peptides by interfering with APP cleavage at the gamma-secretase step, but do not inhibit Notch processing. Importantly, lithium also blocks the accumulation of Abeta peptides in the brains of mice that overproduce APP. The target of lithium in this setting is GSK-3alpha, which is required for maximal processing of APP. Since GSK-3 also phosphorylates tau protein, the principal component of neurofibrillary tangles, inhibition of GSK-3alpha offers a new approach to reduce the formation of both amyloid plaques and neurofibrillary tangles, two pathological hallmarks of Alzheimer's disease.
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Affiliation(s)
- Christopher J Phiel
- Department of Medicine, Division of Hematology-Oncology and Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Philadelphia 19104-6148, USA
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27
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Phiel CJ, Zhang F, Huang EY, Guenther MG, Lazar MA, Klein PS. Histone deacetylase is a direct target of valproic acid, a potent anticonvulsant, mood stabilizer, and teratogen. J Biol Chem 2001; 276:36734-41. [PMID: 11473107 DOI: 10.1074/jbc.m101287200] [Citation(s) in RCA: 1253] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Valproic acid is widely used to treat epilepsy and bipolar disorder and is also a potent teratogen, but its mechanisms of action in any of these settings are unknown. We report that valproic acid activates Wntdependent gene expression, similar to lithium, the mainstay of therapy for bipolar disorder. Valproic acid, however, acts through a distinct pathway that involves direct inhibition of histone deacetylase (IC(50) for HDAC1 = 0.4 mm). At therapeutic levels, valproic acid mimics the histone deacetylase inhibitor trichostatin A, causing hyperacetylation of histones in cultured cells. Valproic acid, like trichostatin A, also activates transcription from diverse exogenous and endogenous promoters. Furthermore, valproic acid and trichostatin A have remarkably similar teratogenic effects in vertebrate embryos, while non-teratogenic analogues of valproic acid do not inhibit histone deacetylase and do not activate transcription. Based on these observations, we propose that inhibition of histone deacetylase provides a mechanism for valproic acid-induced birth defects and could also explain the efficacy of valproic acid in the treatment of bipolar disorder.
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Affiliation(s)
- C J Phiel
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148, USA
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28
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Phiel CJ, Gabbeta V, Parsons LM, Rothblat D, Harvey RP, McHugh KM. Differential binding of an SRF/NK-2/MEF2 transcription factor complex in normal versus neoplastic smooth muscle tissues. J Biol Chem 2001; 276:34637-50. [PMID: 11457859 DOI: 10.1074/jbc.m105826200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The malignant potential of smooth muscle tumors correlates strongly with the disappearance of gamma-smooth muscle isoactin, a lineage-specific marker of smooth muscle development. In this paper, we identify a 36-base pair regulatory motif containing an AT-rich domain, CArG box, and a non-canonical NK-2 homeodomain-binding site that has the capacity to regulate smooth muscle-specific gene expression in cultured intestinal smooth muscle cells. Serum-response factor associates with an NK-2 transcription factor via protein-protein interactions and binds to the core CArG box element. Our studies suggest that the NK-2 transcription factor that associates with serum-response factor during smooth muscle differentiation is Nkx2-3. Myocyte-specific enhancer factor 2 binding to this regulatory complex was also observed but limited to uterine smooth muscle tissues. Smooth muscle neoplasms displayed altered transcription factor binding when compared with normal myometrium. Differential nuclear accessibility of serum-response factor protein during smooth muscle differentiation and neoplastic transformation was also observed. Thus, we have identified a unique regulatory complex whose differential binding properties and nuclear accessibility are associated with modulating gamma-smooth muscle isoactin-specific gene expression in both normal and neoplastic tissues.
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Affiliation(s)
- C J Phiel
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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29
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Abstract
Lithium is highly effective in the treatment of bipolar disorder and also has multiple effects on embryonic development, glycogen synthesis, hematopoiesis, and other processes. However, the mechanism of lithium action is still unclear. A number of enzymes have been proposed as potential targets of lithium action, including inositol monophosphatase, a family of structurally related phosphomonoesterases, and the protein kinase glycogen synthase kinase-3. These potential targets are widely expressed, require metal ions for catalysis, and are generally inhibited by lithium in an uncompetitive manner, most likely by displacing a divalent cation. Thus, the challenge is to determine which target, if any, is responsible for a given response to lithium in cells. Comparison of lithium effects with genetic disruption of putative target molecules has helped to validate these targets, and the use of alternative inhibitors of a given target can also lend strong support for or against a proposed mechanism of lithium action. In this review, lithium sensitive enzymes are discussed, and a number of criteria are proposed to evaluate which of these enzymes are involved in the response to lithium in a given setting.
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Affiliation(s)
- C J Phiel
- Department of Medicine and Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104. USA.
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