1
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Hoboth P, Sztacho M, Hozák P. Nuclear patterns of phosphatidylinositol 4,5- and 3,4-bisphosphate revealed by super-resolution microscopy differ between the consecutive stages of RNA polymerase II transcription. FEBS J 2024. [PMID: 38734927 DOI: 10.1111/febs.17136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 12/12/2023] [Accepted: 04/05/2024] [Indexed: 05/13/2024]
Abstract
Phosphatidylinositol phosphates are powerful signaling molecules that orchestrate signaling and direct membrane trafficking in the cytosol. Interestingly, phosphatidylinositol phosphates also localize within the membrane-less compartments of the cell nucleus, where they participate in the regulation of gene expression. Nevertheless, current models of gene expression, which include condensates of proteins and nucleic acids, do not include nuclear phosphatidylinositol phosphates. This gap is partly a result of the missing detailed analysis of the subnuclear distribution of phosphatidylinositol phosphates and their relationships with gene expression. Here, we used quantitative dual-color direct stochastic optical reconstruction microscopy to analyze the nanoscale co-patterning between RNA polymerase II transcription initiation and elongation markers with respect to phosphatidylinositol 4,5- or 3,4-bisphosphate in the nucleoplasm and nuclear speckles and compared it with randomized data and cells with inhibited transcription. We found specific co-patterning of the transcription initiation marker P-S5 with phosphatidylinositol 4,5-bisphosphate in the nucleoplasm and with phosphatidylinositol 3,4-bisphosphate at the periphery of nuclear speckles. We showed the specific accumulation of the transcription elongation marker PS-2 and of nascent RNA in the proximity of phosphatidylinositol 3,4-bisphosphate associated with nuclear speckles. Taken together, this shows that the distinct spatial associations between the consecutive stages of RNA polymerase II transcription and nuclear phosphatidylinositol phosphates exhibit specificity within the gene expression compartments. Thus, in analogy to the cellular membranes, where phospholipid composition orchestrates signaling pathways and directs membrane trafficking, we propose a model in which the phospholipid identity of gene expression compartments orchestrates RNA polymerase II transcription.
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Affiliation(s)
- Peter Hoboth
- Laboratory of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- Viničná Microscopy Core Facility, Faculty of Science, Charles University, Prague, Czech Republic
| | - Martin Sztacho
- Laboratory of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- Laboratory of Cancer Cell Architecture, Institute of Biochemistry and Experimental Oncology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Pavel Hozák
- Laboratory of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
- Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
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2
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Cui H, Shi Q, Macarios CM, Schimmel P. Metabolic regulation of mRNA splicing. Trends Cell Biol 2024:S0962-8924(24)00025-4. [PMID: 38431493 DOI: 10.1016/j.tcb.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 03/05/2024]
Abstract
Alternative mRNA splicing enables the diversification of the proteome from a static genome and confers plasticity and adaptiveness on cells. Although this is often explored in development, where hard-wired programs drive the differentiation and specialization, alternative mRNA splicing also offers a way for cells to react to sudden changes in outside stimuli such as small-molecule metabolites. Fluctuations in metabolite levels and availability in particular convey crucial information to which cells react and adapt. We summarize and highlight findings surrounding the metabolic regulation of mRNA splicing. We discuss the principles underlying the biochemistry and biophysical properties of mRNA splicing, and propose how these could intersect with metabolite levels. Further, we present examples in which metabolites directly influence RNA-binding proteins and splicing factors. We also discuss the interplay between alternative mRNA splicing and metabolite-responsive signaling pathways. We hope to inspire future research to obtain a holistic picture of alternative mRNA splicing in response to metabolic cues.
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Affiliation(s)
- Haissi Cui
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.
| | - Qingyu Shi
- Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
| | | | - Paul Schimmel
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, CA 92037, USA.
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3
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Dumelie JG, Chen Q, Miller D, Attarwala N, Gross SS, Jaffrey SR. Biomolecular condensates create phospholipid-enriched microenvironments. Nat Chem Biol 2024; 20:302-313. [PMID: 37973889 PMCID: PMC10922641 DOI: 10.1038/s41589-023-01474-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 10/08/2023] [Indexed: 11/19/2023]
Abstract
Proteins and RNA can phase separate from the aqueous cellular environment to form subcellular compartments called condensates. This process results in a protein-RNA mixture that is chemically different from the surrounding aqueous phase. Here, we use mass spectrometry to characterize the metabolomes of condensates. To test this, we prepared mixtures of phase-separated proteins and extracts of cellular metabolites and identified metabolites enriched in the condensate phase. Among the most condensate-enriched metabolites were phospholipids, due primarily to the hydrophobicity of their fatty acyl moieties. We found that phospholipids can alter the number and size of phase-separated condensates and in some cases alter their morphology. Finally, we found that phospholipids partition into a diverse set of endogenous condensates as well as artificial condensates expressed in cells. Overall, these data show that many condensates are protein-RNA-lipid mixtures with chemical microenvironments that are ideally suited to facilitate phospholipid biology and signaling.
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Affiliation(s)
- Jason G Dumelie
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Qiuying Chen
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Dawson Miller
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Nabeel Attarwala
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Steven S Gross
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, NY, USA.
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4
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Escudeiro-Lopes S, Filimonenko VV, Jarolimová L, Hozák P. Lamin A/C and PI(4,5)P2-A Novel Complex in the Cell Nucleus. Cells 2024; 13:399. [PMID: 38474363 DOI: 10.3390/cells13050399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 02/06/2024] [Accepted: 02/10/2024] [Indexed: 03/14/2024] Open
Abstract
Lamins, the nuclear intermediate filaments, are important regulators of nuclear structural integrity as well as nuclear functional processes such as DNA transcription, replication and repair, and epigenetic regulations. A portion of phosphorylated lamin A/C localizes to the nuclear interior in interphase, forming a lamin A/C pool with specific properties and distinct functions. Nucleoplasmic lamin A/C molecular functions are mainly dependent on its binding partners; therefore, revealing new interactions could give us new clues on the lamin A/C mechanism of action. In the present study, we show that lamin A/C interacts with nuclear phosphoinositides (PIPs), and with nuclear myosin I (NM1). Both NM1 and nuclear PIPs have been previously reported as important regulators of gene expression and DNA damage/repair. Furthermore, phosphorylated lamin A/C forms a complex with NM1 in a phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2)-dependent manner in the nuclear interior. Taken together, our study reveals a previously unidentified interaction between phosphorylated lamin A/C, NM1, and PI(4,5)P2 and suggests new possible ways of nucleoplasmic lamin A/C regulation, function, and importance for the formation of functional nuclear microdomains.
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Affiliation(s)
- Sara Escudeiro-Lopes
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Vlada V Filimonenko
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
- Electron Microscopy Core Facility, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Lenka Jarolimová
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
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5
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Kato M, Watari M, Tsuge T, Zhong S, Gu H, Qu LJ, Fujiwara T, Aoyama T. Redundant function of the Arabidopsis phosphatidylinositol 4-phosphate 5-kinase genes PIP5K4-6 is essential for pollen germination. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:212-225. [PMID: 37828913 DOI: 10.1111/tpj.16490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/02/2023] [Accepted: 09/05/2023] [Indexed: 10/14/2023]
Abstract
Phosphatidylinositol 4-phosphate 5-kinase (PIP5K) is a key enzyme producing the signaling lipid phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2 ] in eukaryotes. Although PIP5K genes are reported to be involved in pollen tube germination and growth, the essential roles of PIP5K in these processes remain unclear. Here, we performed a comprehensive genetic analysis of the Arabidopsis thaliana PIP5K4, PIP5K5, and PIP5K6 genes and revealed that their redundant function is essential for pollen germination. Pollen with the pip5k4pip5k5pip5k6 triple mutation was sterile, while pollen germination efficiency and pollen tube growth were reduced in the pip5k6 single mutant and further reduced in the pip5k4pip5k6 and pip5k5pip5k6 double mutants. YFP-fusion proteins, PIP5K4-YFP, PIP5K5-YFP, and PIP5K6-YFP, which could rescue the sterility of the triple mutant pollen, preferentially localized to the tricolpate aperture area and the future germination site on the plasma membrane prior to germination. Triple mutant pollen grains under the germination condition, in which spatiotemporal localization of the PtdIns(4,5)P2 fluorescent marker protein 2xmCHERRY-2xPHPLC as seen in the wild type was abolished, exhibited swelling and rupture of the pollen wall, but neither the conspicuous protruding site nor site-specific deposition of cell wall materials for germination. These data indicate that PIP5K4-6 and their product PtdIns(4,5)P2 are essential for pollen germination, possibly through the establishment of the germination polarity in a pollen grain.
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Affiliation(s)
- Mariko Kato
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Machiko Watari
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Tomohiko Tsuge
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Sheng Zhong
- Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Hongya Gu
- Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Li-Jia Qu
- Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Takashi Fujiwara
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Takashi Aoyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
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6
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Li C, Yoon B, Stefani G, Slack FJ. Lipid kinase PIP5K1A regulates let-7 microRNA biogenesis through interacting with nuclear export protein XPO5. Nucleic Acids Res 2023; 51:9849-9862. [PMID: 37655623 PMCID: PMC10570020 DOI: 10.1093/nar/gkad709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/03/2023] [Accepted: 08/15/2023] [Indexed: 09/02/2023] Open
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs first discovered in Caenorhabditis elegans. The let-7 miRNA is highly conserved in sequence, biogenesis and function from C. elegans to humans. During miRNA biogenesis, XPO5-mediated nuclear export of pre-miRNAs is a rate-limiting step and, therefore, might be critical for the quantitative control of miRNA levels, yet little is known about how this is regulated. Here we show a novel role for lipid kinase PPK-1/PIP5K1A (phosphatidylinositol-4-phosphate 5-kinase) in regulating miRNA levels. We found that C. elegans PPK-1 functions in the lin-28/let-7 heterochronic pathway, which regulates the strict developmental timing of seam cells. In C. elegans and human cells, PPK-1/PIP5K1A regulates let-7 miRNA levels. We investigated the mechanism further in human cells and show that PIP5K1A interacts with nuclear export protein XPO5 in the nucleus to regulate mature miRNA levels by blocking the binding of XPO5 to pre-let-7 miRNA. Furthermore, we demonstrate that this role for PIP5K1A is kinase-independent. Our study uncovers the novel finding of a direct connection between PIP5K1A and miRNA biogenesis. Given that miRNAs are implicated in multiple diseases, including cancer, this new finding might lead to a novel therapeutic opportunity.
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Affiliation(s)
- Chun Li
- Harvard Medical School Initiative for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Bohyung Yoon
- Harvard Medical School Initiative for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Giovanni Stefani
- Harvard Medical School Initiative for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Frank J Slack
- Harvard Medical School Initiative for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
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7
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Hoboth P, Sztacho M, Quaas A, Akgül B, Hozák P. Quantitative super-resolution microscopy reveals the differences in the nanoscale distribution of nuclear phosphatidylinositol 4,5-bisphosphate in human healthy skin and skin warts. Front Cell Dev Biol 2023; 11:1217637. [PMID: 37484912 PMCID: PMC10361526 DOI: 10.3389/fcell.2023.1217637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/22/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction: Imaging of human clinical formalin-fixed paraffin-embedded (FFPE) tissue sections provides insights into healthy and diseased states and therefore represents a valuable resource for basic research, as well as for diagnostic and clinical purposes. However, conventional light microscopy does not allow to observe the molecular details of tissue and cell architecture due to the diffraction limit of light. Super-resolution microscopy overcomes this limitation and provides access to the nanoscale details of tissue and cell organization. Methods: Here, we used quantitative multicolor stimulated emission depletion (STED) nanoscopy to study the nanoscale distribution of the nuclear phosphatidylinositol 4,5-bisphosphate (nPI(4,5)P2) with respect to the nuclear speckles (NS) marker SON. Results: Increased nPI(4,5)P2 signals were previously linked to human papillomavirus (HPV)-mediated carcinogenesis, while NS-associated PI(4,5)P2 represents the largest pool of nPI(4,5)P2 visualized by staining and microscopy. The implementation of multicolor STED nanoscopy in human clinical FFPE skin and wart sections allowed us to provide here the quantitative evidence for higher levels of NS-associated PI(4,5)P2 in HPV-induced warts compared to control skin. Discussion: These data expand the previous reports of HPV-induced increase of nPI(4,5)P2 levels and reveal for the first time the functional, tissue-specific localization of nPI(4,5)P2 within NS in clinically relevant samples. Moreover, our approach is widely applicable to other human clinical FFPE tissues as an informative addition to the classical histochemistry.
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Affiliation(s)
- Peter Hoboth
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Martin Sztacho
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
| | - Alexander Quaas
- Institute of Pathology, Medical Faculty and University Hospital Cologne, Cologne, Germany
| | - Baki Akgül
- Institute of Virology, University of Cologne, Medical Faculty and University Hospital Cologne, Cologne, Germany
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
- Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czechia
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8
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Vidalle MC, Sheth B, Fazio A, Marvi MV, Leto S, Koufi FD, Neri I, Casalin I, Ramazzotti G, Follo MY, Ratti S, Manzoli L, Gehlot S, Divecha N, Fiume R. Nuclear Phosphoinositides as Key Determinants of Nuclear Functions. Biomolecules 2023; 13:1049. [PMID: 37509085 PMCID: PMC10377365 DOI: 10.3390/biom13071049] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
Polyphosphoinositides (PPIns) are signalling messengers representing less than five per cent of the total phospholipid concentration within the cell. Despite their low concentration, these lipids are critical regulators of various cellular processes, including cell cycle, differentiation, gene transcription, apoptosis and motility. PPIns are generated by the phosphorylation of the inositol head group of phosphatidylinositol (PtdIns). Different pools of PPIns are found at distinct subcellular compartments, which are regulated by an array of kinases, phosphatases and phospholipases. Six of the seven PPIns species have been found in the nucleus, including the nuclear envelope, the nucleoplasm and the nucleolus. The identification and characterisation of PPIns interactor and effector proteins in the nucleus have led to increasing interest in the role of PPIns in nuclear signalling. However, the regulation and functions of PPIns in the nucleus are complex and are still being elucidated. This review summarises our current understanding of the localisation, biogenesis and physiological functions of the different PPIns species in the nucleus.
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Affiliation(s)
- Magdalena C Vidalle
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Bhavwanti Sheth
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Antonietta Fazio
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Maria Vittoria Marvi
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Stefano Leto
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Foteini-Dionysia Koufi
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Neri
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Casalin
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Giulia Ramazzotti
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Matilde Y Follo
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Stefano Ratti
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Lucia Manzoli
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Sonakshi Gehlot
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Nullin Divecha
- Inositide Laboratory, School of Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Roberta Fiume
- Department of Biomedical Sciences (DIBINEM), University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
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9
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Palmieri M, Catimel B, Mouradov D, Sakthianandeswaren A, Kapp E, Ang CS, Williamson NA, Nowell CJ, Christie M, Desai J, Gibbs P, Burgess AW, Sieber OM. PI3K-alpha translocation mediates nuclear PtdIns(3,4,5)P 3 effector signaling in colorectal cancer. Mol Cell Proteomics 2023; 22:100529. [PMID: 36931626 PMCID: PMC10130476 DOI: 10.1016/j.mcpro.2023.100529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 03/05/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023] Open
Abstract
The canonical view of phosphatidylinositol 3-kinase alpha (PI3Kα) signaling describes PtdIns(3,4,5)P3 generation and activation of downstream effectors at the plasma membrane or at microtubule-bound endosomes. Here, we show that colorectal cancer (CRC) cell lines exhibit a diverse plasma membrane-nuclear distribution of PI3Kα, controlling corresponding levels of subcellular PtdIns(3,4,5)P3 pools. PI3Kα nuclear translocation was mediated by the importin β-dependent nuclear import pathway. By PtdIns(3,4,5)P3 affinity capture mass spectrometry done in the presence of SDS on CRC cell lines with PI3Kα nuclear localization, we identified 867 potential nuclear PtdIns(3,4,5)P3 effector proteins. Nuclear PtdIns(3,4,5)P3 interactome proteins were characterized by non-canonical PtdIns(3,4,5)P3 binding domains and showed overrepresentation for nuclear membrane, nucleolus and nuclear speckles. The nuclear PtdIns(3,4,5)P3 interactome was enriched for proteins related to RNA metabolism, with splicing reporter assays and SC-35 foci staining suggesting a role of EGF-stimulated nuclear PI3Kα signaling in modulating pre-mRNA splicing. In patient tumors, nuclear p110α staining was associated with lower T stage and mucinous histology. These results indicate that PI3Kα translocation mediates nuclear PtdIns(3,4,5)P3 effector signaling in human CRC, modulating signaling responses.
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Affiliation(s)
- Michelle Palmieri
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Bruno Catimel
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Dmitri Mouradov
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Anuratha Sakthianandeswaren
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Eugene Kapp
- Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia; Advanced Technology and Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia
| | - Ching-Seng Ang
- Bio21 Mass Spectrometry and Proteomics Facility, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Nicholas A Williamson
- Bio21 Mass Spectrometry and Proteomics Facility, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Cameron J Nowell
- Monash Institute for Pharmaceutical Science, Parkville, Victoria, 3052, Australia
| | - Michael Christie
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Pathology, Royal Melbourne Hospital, Parkville, Victoria, 3050, Australia
| | - Jayesh Desai
- Division of Cancer Medicine, Peter MacCallum Cancer Centre, Melbourne, Victoria, 3000, Australia; Department of Medical Oncology, Royal Melbourne Hospital, Parkville, Victoria, 3050, Australia
| | - Peter Gibbs
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia; Department of Medical Oncology, Western Health, Footscray, Victoria, 3011, Australia
| | - Antony W Burgess
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia; Department of Surgery, The University of Melbourne, Parkville, Victoria, 3050, Australia
| | - Oliver M Sieber
- Personalised Oncology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, 3052, Australia; Department of Surgery, The University of Melbourne, Parkville, Victoria, 3050, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia.
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10
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Balaban C, Sztacho M, Antiga L, Miladinović A, Harata M, Hozák P. PIP2-Effector Protein MPRIP Regulates RNA Polymerase II Condensation and Transcription. Biomolecules 2023; 13:biom13030426. [PMID: 36979361 PMCID: PMC10046169 DOI: 10.3390/biom13030426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/17/2023] [Accepted: 02/21/2023] [Indexed: 03/02/2023] Open
Abstract
The specific post-translational modifications of the C-terminal domain (CTD) of the Rpb1 subunit of RNA polymerase II (RNAPII) correlate with different stages of transcription. The phosphorylation of the Ser5 residues of this domain associates with the initiation condensates, which are formed through liquid-liquid phase separation (LLPS). The subsequent Tyr1 phosphorylation of the CTD peaks at the promoter-proximal region and is involved in the pause-release of RNAPII. By implementing super-resolution microscopy techniques, we previously reported that the nuclear Phosphatidylinositol 4,5-bisphosphate (PIP2) associates with the Ser5-phosphorylated-RNAPII complex and facilitates the RNAPII transcription. In this study, we identified Myosin Phosphatase Rho-Interacting Protein (MPRIP) as a novel regulator of the RNAPII transcription that recruits Tyr1-phosphorylated CTD (Tyr1P-CTD) to nuclear PIP2-containing structures. The depletion of MPRIP increases the number of the initiation condensates, indicating a defect in the transcription. We hypothesize that MPRIP regulates the condensation and transcription through affecting the association of the RNAPII complex with nuclear PIP2-rich structures. The identification of Tyr1P-CTD as an interactor of PIP2 and MPRIP further points to a regulatory role in RNAPII pause-release, where the susceptibility of the transcriptional complex to leave the initiation condensate depends on its association with nuclear PIP2-rich structures. Moreover, the N-terminal domain of MPRIP, which is responsible for the interaction with the Tyr1P-CTD, contains an F-actin binding region that offers an explanation of how nuclear F-actin formations can affect the RNAPII transcription and condensation. Overall, our findings shed light on the role of PIP2 in RNAPII transcription through identifying the F-actin binding protein MPRIP as a transcription regulator and a determinant of the condensation of RNAPII.
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Affiliation(s)
- Can Balaban
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Martin Sztacho
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
- Correspondence: (M.S.); (P.H.)
| | - Ludovica Antiga
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Ana Miladinović
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Masahiko Harata
- Laboratory of Molecular Biochemistry, Division of Life Science, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
- Correspondence: (M.S.); (P.H.)
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11
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Aretxabala X, García del Caño G, Barrondo S, López de Jesús M, González-Burguera I, Saumell-Esnaola M, Goicolea MA, Sallés J. Endocannabinoid 2-Arachidonoylglycerol Synthesis and Metabolism at Neuronal Nuclear Matrix Fractions Derived from Adult Rat Brain Cortex. Int J Mol Sci 2023; 24:ijms24043165. [PMID: 36834575 PMCID: PMC9965625 DOI: 10.3390/ijms24043165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/08/2023] Open
Abstract
In this report, we describe the kinetics characteristics of the diacylglycerol lipase-α (DGLα) located at the nuclear matrix of nuclei derived from adult cortical neurons. Thus, using high-resolution fluorescence microscopy, classical biochemical subcellular fractionation, and Western blot techniques, we demonstrate that the DGLα enzyme is located in the matrix of neuronal nuclei. Furthermore, by quantifying the 2-arachidonoylglycerol (2-AG) level by liquid chromatography and mass spectrometry when 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG) was exogenously added as substrate, we describe the presence of a mechanism for 2-AG production through DGLα dependent biosynthesis with an apparent Km (Kmapp) of 180 µM and a Vmax of 1.3 pmol min-1 µg-1 protein. We also examined the presence of enzymes with hydrolytic and oxygenase activities that are able to use 2-AG as substrate, and described the localization and compartmentalization of the major 2-AG degradation enzymes, namely monoacylglycerol lipase (MGL), fatty acid amide hydrolase (FAAH), α/β-hydrolase domain 12 protein (ABHD12) and cyclooxygenase-2 (COX2). Of these, only ABHD12 exhibited the same distribution with respect to chromatin, lamin B1, SC-35 and NeuN as that described for DGLα. When 2-AG was exogenously added, we observed the production of arachidonic acid (AA), which was prevented by inhibitors (but not specific MGL or ABHD6 inhibitors) of the ABHD family. Overall, our results expand knowledge about the subcellular distribution of neuronal DGLα, and provide biochemical and morphological evidence to ensure that 2-AG is produced in the neuronal nuclear matrix. Thus, this work paves the way for proposing a working hypothesis about the role of 2-AG produced in neuronal nuclei.
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Affiliation(s)
- Xabier Aretxabala
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
| | - Gontzal García del Caño
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
- Bioaraba, Neurofarmacología Celular y Molecular, 01008 Vitoria-Gasteiz, Spain
| | - Sergio Barrondo
- Bioaraba, Neurofarmacología Celular y Molecular, 01008 Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 28029 Madrid, Spain
| | - Maider López de Jesús
- Bioaraba, Neurofarmacología Celular y Molecular, 01008 Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
| | - Imanol González-Burguera
- Department of Neurosciences, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
- Bioaraba, Neurofarmacología Celular y Molecular, 01008 Vitoria-Gasteiz, Spain
| | - Miquel Saumell-Esnaola
- Bioaraba, Neurofarmacología Celular y Molecular, 01008 Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
| | - María Aranzazu Goicolea
- Department of Analytical Chemistry, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
| | - Joan Sallés
- Bioaraba, Neurofarmacología Celular y Molecular, 01008 Vitoria-Gasteiz, Spain
- Department of Pharmacology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), 01006 Vitoria-Gasteiz, Spain
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-945-013114
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12
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Zhu C, Iwase M, Li Z, Wang F, Quinet A, Vindigni A, Shao J. Profilin-1 regulates DNA replication forks in a context-dependent fashion by interacting with SNF2H and BOD1L. Nat Commun 2022; 13:6531. [PMID: 36319634 PMCID: PMC9626489 DOI: 10.1038/s41467-022-34310-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 10/21/2022] [Indexed: 12/04/2022] Open
Abstract
DNA replication forks are tightly controlled by a large protein network consisting of well-known core regulators and many accessory factors which remain functionally undefined. In this study, we report previously unknown nuclear functions of the actin-binding factor profilin-1 (PFN1) in DNA replication, which occur in a context-dependent fashion and require its binding to poly-L-proline (PLP)-containing proteins instead of actin. In unperturbed cells, PFN1 increases DNA replication initiation and accelerates fork progression by binding and stimulating the PLP-containing nucleosome remodeler SNF2H. Under replication stress, PFN1/SNF2H increases fork stalling and functionally collaborates with fork reversal enzymes to enable the over-resection of unprotected forks. In addition, PFN1 binds and functionally attenuates the PLP-containing fork protector BODL1 to increase the resection of a subset of stressed forks. Accordingly, raising nuclear PFN1 level decreases genome stability and cell survival during replication stress. Thus, PFN1 is a multi-functional regulator of DNA replication with exploitable anticancer potential.
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Affiliation(s)
- Cuige Zhu
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Mari Iwase
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Ziqian Li
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Microbial and Biochemical Pharmacy, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China
| | - Faliang Wang
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Annabel Quinet
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- UMR Genetic Stability Stem Cells and Radiation, University of Paris and University of Paris-Saclay, INSERM, iRCM/IBFJ CEA, Fontenay-aux-Roses, France
| | - Alessandro Vindigni
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jieya Shao
- Divison of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, 63110, USA.
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13
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Faber GP, Nadav-Eliyahu S, Shav-Tal Y. Nuclear speckles - a driving force in gene expression. J Cell Sci 2022; 135:275909. [PMID: 35788677 DOI: 10.1242/jcs.259594] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Nuclear speckles are dynamic membraneless bodies located in the cell nucleus. They harbor RNAs and proteins, many of which are splicing factors, that together display complex biophysical properties dictating nuclear speckle formation and maintenance. Although these nuclear bodies were discovered decades ago, only recently has in-depth genomic analysis begun to unravel their essential functions in modulation of gene activity. Major advancements in genomic mapping techniques combined with microscopy approaches have enabled insights into the roles nuclear speckles may play in enhancing gene expression, and how gene positioning to specific nuclear landmarks can regulate gene expression and RNA processing. Some studies have drawn a link between nuclear speckles and disease. Certain maladies either involve nuclear speckles directly or dictate the localization and reorganization of many nuclear speckle factors. This is most striking during viral infection, as viruses alter the entire nuclear architecture and highjack host machinery. As discussed in this Review, nuclear speckles represent a fascinating target of study not only to reveal the links between gene positioning, genome subcompartments and gene activity, but also as a potential target for therapeutics.
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Affiliation(s)
- Gabriel P Faber
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Shani Nadav-Eliyahu
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences , Bar-Ilan University, Ramat Gan 5290002, Israel.,Institute of Nanotechnology , Bar-Ilan University, Ramat Gan 5290002, Israel
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14
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Wang YH, Sheetz MP. When PIP2 Meets p53: Nuclear Phosphoinositide Signaling in the DNA Damage Response. Front Cell Dev Biol 2022; 10:903994. [PMID: 35646908 PMCID: PMC9136457 DOI: 10.3389/fcell.2022.903994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
The mechanisms that maintain genome stability are critical for preventing tumor progression. In the past decades, many strategies were developed for cancer treatment to disrupt the DNA repair machinery or alter repair pathway selection. Evidence indicates that alterations in nuclear phosphoinositide lipids occur rapidly in response to genotoxic stresses. This implies that nuclear phosphoinositides are an upstream element involved in DNA damage signaling. Phosphoinositides constitute a new signaling interface for DNA repair pathway selection and hence a new opportunity for developing cancer treatment strategies. However, our understanding of the underlying mechanisms by which nuclear phosphoinositides regulate DNA damage repair, and particularly the dynamics of those processes, is rather limited. This is partly because there are a limited number of techniques that can monitor changes in the location and/or abundance of nuclear phosphoinositide lipids in real time and in live cells. This review summarizes our current knowledge regarding the roles of nuclear phosphoinositides in DNA damage response with an emphasis on the dynamics of these processes. Based upon recent findings, there is a novel model for p53’s role with nuclear phosphoinositides in DNA damage response that provides new targets for synthetic lethality of tumors.
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15
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Morovicz AP, Mazloumi Gavgani F, Jacobsen RG, Skuseth Slinning M, Turcu DC, Lewis AE. Phosphoinositide 3-kinase signalling in the nucleolus. Adv Biol Regul 2021; 83:100843. [PMID: 34920983 DOI: 10.1016/j.jbior.2021.100843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 12/26/2022]
Abstract
The phosphoinositide 3-kinase (PI3K) signalling pathway plays key roles in many cellular processes and is altered in many diseases. The function and mode of action of the pathway have mostly been elucidated in the cytoplasm. However, many of the components of the PI3K pathway are also present in the nucleus at specific sub-nuclear sites including nuclear speckles, nuclear lipid islets and the nucleolus. Nucleoli are membrane-less subnuclear structures where ribosome biogenesis occurs. Processes leading to ribosome biogenesis are tightly regulated to maintain protein translation capacity of cells. This review focuses on nucleolar PI3K signalling and how it regulates rRNA synthesis, as well as on the identification of downstream phosphatidylinositol (3,4,5)trisphosphate effector proteins.
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Affiliation(s)
| | | | - Rhîan G Jacobsen
- Department of Biological Sciences, University of Bergen, 5008, Bergen, Norway
| | | | - Diana C Turcu
- Department of Biological Sciences, University of Bergen, 5008, Bergen, Norway
| | - Aurélia E Lewis
- Department of Biological Sciences, University of Bergen, 5008, Bergen, Norway.
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16
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Moriel-Carretero M. The Many Faces of Lipids in Genome Stability (and How to Unmask Them). Int J Mol Sci 2021; 22:12930. [PMID: 34884734 PMCID: PMC8657548 DOI: 10.3390/ijms222312930] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/12/2021] [Accepted: 11/26/2021] [Indexed: 12/15/2022] Open
Abstract
Deep efforts have been devoted to studying the fundamental mechanisms ruling genome integrity preservation. A strong focus relies on our comprehension of nucleic acid and protein interactions. Comparatively, our exploration of whether lipids contribute to genome homeostasis and, if they do, how, is severely underdeveloped. This disequilibrium may be understood in historical terms, but also relates to the difficulty of applying classical lipid-related techniques to a territory such as a nucleus. The limited research in this domain translates into scarce and rarely gathered information, which with time further discourages new initiatives. In this review, the ways lipids have been demonstrated to, or very likely do, impact nuclear transactions, in general, and genome homeostasis, in particular, are explored. Moreover, a succinct yet exhaustive battery of available techniques is proposed to tackle the study of this topic while keeping in mind the feasibility and habits of "nucleus-centered" researchers.
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Affiliation(s)
- María Moriel-Carretero
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, CEDEX 5, 34293 Montpellier, France
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17
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The basis of nuclear phospholipase C in cell proliferation. Adv Biol Regul 2021; 82:100834. [PMID: 34710785 DOI: 10.1016/j.jbior.2021.100834] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/17/2021] [Accepted: 10/21/2021] [Indexed: 11/23/2022]
Abstract
Ca2+ is a highly versatile intracellular signal that regulates many biological processes such as cell death and proliferation. Broad Ca2+-signaling machinery is used to assemble signaling systems with a precise spatial and temporal resolution to achieve this versatility. Ca2+-signaling components can be organized in different regions of the cell and local increases in Ca2+ within the nucleus can regulate different cellular functions from the increases in cytosolic Ca2+. However, the mechanisms and pathways that promote localized increases in Ca2+ levels in the nucleus are still under investigation. This review presents evidence that the nucleus has its own Ca2+ stores and signaling machinery, which modulate processes such as cell proliferation and tumor growth. We focus on what is known about the functions of nuclear Phospholipase C (PLC) in the generation of nuclear Ca2+ transients that are involved in cell proliferation.
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18
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Hoboth P, Šebesta O, Sztacho M, Castano E, Hozák P. Dual-color dSTORM imaging and ThunderSTORM image reconstruction and analysis to study the spatial organization of the nuclear phosphatidylinositol phosphates. MethodsX 2021; 8:101372. [PMID: 34430268 PMCID: PMC8374474 DOI: 10.1016/j.mex.2021.101372] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/23/2021] [Indexed: 11/02/2022] Open
Abstract
Single molecule localization microscopy (SMLM) provided an unprecedented insight into the sub-nuclear organization of proteins and nucleic acids but apart from the nuclear envelope the role of the nuclear lipids in the functional organization of the cell nucleus was less studied. Nevertheless, nuclear lipids and specifically phosphatidylinositol phosphates (PIPs) play increasingly evident roles in gene expression. Therefore, here we provide the SMLM-based approach for the quantitative evaluation of the nuclear PIPs distribution while preserving the context of nuclear architecture. Specifically, on the example of phosphatidylinositol 4,5-bisphosphate (PIP2) we have:•Implemented and optimized the dual-color dSTORM imaging of nuclear PIP2.•Customized the Nearest Neighbor Distance analysis using ImageJ2 plug-in ThunderSTORM to quantitatively evaluate the spatial distribution of nuclear PIP2.•Developed an ImageJ2 tool for the visualization of the Nearest Neighbor Distance analysis results in cellulo.Our customization of the dual-color dSTORM imaging and quantitative analysis provide a tool that is independent of but complementary to the biochemical and lipidomic analyses of the nuclear PIPs. Contrary to the biochemical and lipidomic analyses, the advantage of our analysis is that it preserves the spatial context of the nuclear PIP distribution.
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Affiliation(s)
- Peter Hoboth
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Vídeňská 1083, 142 20, Czech Republic.,Faculty of Science, Charles University, Albertov 6, Prague 128 00, Czech Republic
| | - Ondřej Šebesta
- Faculty of Science, Charles University, Albertov 6, Prague 128 00, Czech Republic
| | - Martin Sztacho
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Vídeňská 1083, 142 20, Czech Republic
| | - Enrique Castano
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Vídeňská 1083, 142 20, Czech Republic.,Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Yucatán, Mérida C.P. 97200, Yucatán, Mexico
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Vídeňská 1083, 142 20, Czech Republic.,Microscopy Centre of the Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Vídeňská 1083, 142 20, Czech Republic
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19
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Nuclear Phosphatidylinositol 3,4,5-Trisphosphate Interactome Uncovers an Enrichment in Nucleolar Proteins. Mol Cell Proteomics 2021; 20:100102. [PMID: 34048982 PMCID: PMC8255942 DOI: 10.1016/j.mcpro.2021.100102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 05/20/2021] [Indexed: 02/07/2023] Open
Abstract
Polyphosphoinositides (PPIns) play essential roles as lipid signaling molecules, and many of their functions have been elucidated in the cytoplasm. However, PPIns are also intranuclear where they contribute to chromatin remodeling, transcription, and mRNA splicing. The PPIn, phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3), has been mapped to the nucleus and nucleoli, but its role remains unclear in this subcellular compartment. To gain further insights into the nuclear functions of PtdIns(3,4,5)P3, we applied a previously developed quantitative MS-based approach to identify the targets of PtdIns(3,4,5)P3 from isolated nuclei. We identified 179 potential PtdIns(3,4,5)P3-interacting partners, and gene ontology analysis for the biological functions of this dataset revealed an enrichment in RNA processing/splicing, cytokinesis, protein folding, and DNA repair. Interestingly, about half of these interactors were common to nucleolar protein datasets, some of which had dual functions in rRNA processes and DNA repair, including poly(ADP-ribose) polymerase 1 (PARP1, now referred as ADP-ribosyltransferase 1). PARP1 was found to interact directly with PPIn via three polybasic regions in the DNA-binding domain and the linker located N-terminal of the catalytic region. PARP1 was shown to bind to PtdIns(3,4,5)P3 as well as phosphatidylinositol 3,4-bisphosphate in vitro and to colocalize with PtdIns(3,4,5)P3 in the nucleolus and with phosphatidylinositol 3,4-bisphosphate in nucleoplasmic foci. In conclusion, the PtdIns(3,4,5)P3 interactome reported here will serve as a resource to further investigate the molecular mechanisms underlying PtdIns(3,4,5)P3-mediated interactions in the nucleus and nucleolus. Phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3) localizes to nucleoli. PtdIns(3,4,5)P3 interactomics from isolated nuclei identifies nucleolar proteins. PARP1 interacts directly with polyphosphoinositides via several polybasic regions. PARP1 colocalizes with PtdIns(3,4,5)P3 in the nucleolus.
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20
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Mazloumi Gavgani F, Karlsson T, Tangen IL, Morovicz AP, Arnesen VS, Turcu DC, Ninzima S, Spang K, Krakstad C, Guillermet-Guibert J, Lewis AE. Nuclear upregulation of class I phosphoinositide 3-kinase p110β correlates with high 47S rRNA levels in cancer cells. J Cell Sci 2021; 134:jcs.246090. [PMID: 33536247 DOI: 10.1242/jcs.246090] [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: 04/01/2020] [Accepted: 12/24/2020] [Indexed: 12/12/2022] Open
Abstract
The class I phosphoinositide 3-kinase (PI3K) catalytic subunits p110α and p110β are ubiquitously expressed but differently targeted in tumours. In cancer, PIK3CB (encoding p110β) is seldom mutated compared with PIK3CA (encoding p110α) but can contribute to tumorigenesis in certain PTEN-deficient tumours. The underlying molecular mechanisms are, however, unclear. We have previously reported that p110β is highly expressed in endometrial cancer (EC) cell lines and at the mRNA level in primary patient tumours. Here, we show that p110β protein levels are high in both the cytoplasmic and nuclear compartments in EC cells. Moreover, high nuclear:cytoplasmic staining ratios were detected in high-grade primary tumours. High levels of phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P 3] were measured in the nucleus of EC cells, and pharmacological and genetic approaches showed that its production was partly dependent upon p110β activity. Using immunofluorescence staining, p110β and PtdIns(3,4,5)P 3 were localised in the nucleolus, which correlated with high levels of 47S pre-rRNA. p110β inhibition led to a decrease in both 47S rRNA levels and cell proliferation. In conclusion, these results present a nucleolar role for p110β that may contribute to tumorigenesis in EC.This article has an associated First Person interview with Fatemeh Mazloumi Gavgani, joint first author of the paper.
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Affiliation(s)
| | - Thomas Karlsson
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Ingvild L Tangen
- Centre for Cancer Biomarkers, Department of Clinical Science, University of Bergen, Bergen 5021, Norway.,Department of Gynaecology and Obstetrics, Haukeland University Hospital, Bergen 5021, Norway
| | | | | | - Diana C Turcu
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Sandra Ninzima
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Katharina Spang
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Camilla Krakstad
- Centre for Cancer Biomarkers, Department of Clinical Science, University of Bergen, Bergen 5021, Norway.,Department of Gynaecology and Obstetrics, Haukeland University Hospital, Bergen 5021, Norway
| | - Julie Guillermet-Guibert
- Inserm U1037, Centre de Recherches en Cancérologie de Toulouse (CRCT), Institut National de la Santé et de la Recherche Médicale (INSERM), Université Toulouse III Paul Sabatier, 31037 Toulouse, France
| | - Aurélia E Lewis
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
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21
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Hoboth P, Sztacho M, Šebesta O, Schätz M, Castano E, Hozák P. Nanoscale mapping of nuclear phosphatidylinositol phosphate landscape by dual-color dSTORM. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158890. [PMID: 33513445 DOI: 10.1016/j.bbalip.2021.158890] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 01/10/2021] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
Current models of gene expression, which are based on single-molecule localization microscopy, acknowledge protein clustering and the formation of transcriptional condensates as a driving force of gene expression. However, these models largely omit the role of nuclear lipids and amongst them nuclear phosphatidylinositol phosphates (PIPs) in particular. Moreover, the precise distribution of nuclear PIPs in the functional sub-nuclear domains remains elusive. The direct stochastic optical reconstruction microscopy (dSTORM) provides an unprecedented resolution in biological imaging. Therefore, its use for imaging in the densely crowded cell nucleus is desired but also challenging. Here we present a dual-color dSTORM imaging and image analysis of nuclear PI(4,5)P2, PI(3,4)P2 and PI(4)P distribution while preserving the context of nuclear architecture. In the nucleoplasm, PI(4,5)P2 and PI(3,4)P2 co-pattern in close proximity with the subset of RNA polymerase II foci. PI(4,5)P2 is surrounded by fibrillarin in the nucleoli and all three PIPs are dispersed within the matrix formed by the nuclear speckle protein SON. PI(4,5)P2 is the most abundant nuclear PIP, while PI(4)P is a precursor for the biosynthesis of PI(4,5)P2 and PI(3,4)P2. Therefore, our data are relevant for the understanding the roles of nuclear PIPs and provide further evidence for the model in which nuclear PIPs represent a localization signal for the formation of lipo-ribonucleoprotein hubs in the nucleus. The discussed experimental pipeline is applicable for further functional studies on the role of other nuclear PIPs in the regulation of gene expression and beyond.
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Affiliation(s)
- Peter Hoboth
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Martin Sztacho
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
| | - Ondřej Šebesta
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic
| | - Martin Schätz
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic
| | - Enrique Castano
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic; Biochemistry and Molecular Plant Biology Department, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida C.P. 97200, Yucatán, Mexico
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic; Department of Epigenetics of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, division BIOCEV, Průmyslová 595, 252 20 Vestec, Czech Republic; Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic.
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22
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Chen M, Wen T, Horn HT, Chandrahas VK, Thapa N, Choi S, Cryns VL, Anderson RA. The nuclear phosphoinositide response to stress. Cell Cycle 2020; 19:268-289. [PMID: 31902273 PMCID: PMC7028212 DOI: 10.1080/15384101.2019.1711316] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Accumulating evidence reveals that nuclear phosphoinositides (PIs) serve as central signaling hubs that control a multitude of nuclear processes by regulating the activity of nuclear proteins. In response to cellular stressors, PIs accumulate in the nucleus and multiple PI isomers are synthesized by the actions of PI-metabolizing enzymes, kinases, phosphatases and phospholipases. By directly interacting with effector proteins, phosphoinositide signals transduce changes in cellular functions. Here we describe nuclear phosphoinositide signaling in multiple sub-nuclear compartments and summarize the literature that demonstrates roles for specific kinases, phosphatases, and phospholipases in the orchestration of nuclear phosphoinositide signaling in response to cellular stress. Additionally, we discuss the specific PI-protein complexes through which these lipids execute their functions by regulating the configuration, stability, and transcription activity of their effector proteins. Overall, our review provides a detailed landscape of the current understanding of the nuclear PI-protein interactome and its role in shaping the coordinated response to cellular stress.
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Affiliation(s)
- Mo Chen
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Tianmu Wen
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Hudson T. Horn
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Narendra Thapa
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Suyong Choi
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Vincent L. Cryns
- Department of Medicine, University of Wisconsin Carbone Cancer Center, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA
| | - Richard A. Anderson
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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23
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Ramos AR, Ghosh S, Suhel T, Chevalier C, Obeng EO, Fafilek B, Krejci P, Beck B, Erneux C. Phosphoinositide 5-phosphatases SKIP and SHIP2 in ruffles, the endoplasmic reticulum and the nucleus: An update. Adv Biol Regul 2019; 75:100660. [PMID: 31628071 DOI: 10.1016/j.jbior.2019.100660] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/18/2019] [Accepted: 09/30/2019] [Indexed: 01/22/2023]
Abstract
Phosphoinositides (PIs) are phosphorylated derivatives of phosphatidylinositol. They act as signaling molecules linked to essential cellular mechanisms in eukaryotic cells, such as cytoskeleton organization, mitosis, polarity, migration or invasion. PIs are phosphorylated and dephosphorylated by a large number of PI kinases and PI phosphatases acting at the 5-, 4- and 3- position of the inositol ring. PI 5-phosphatases i.e. OCRL, INPP5B, SHIP1/2, Synaptojanin 1/2, INPP5E, INPP5J, SKIP (INPP5K) are enzymes that dephosphorylate the 5-phosphate position of PIs. Several human genetic diseases such as the Lowe syndrome, some congenital muscular dystrophy and opsismodysplasia are due to mutations in PI phosphatases, resulting in loss-of-function. The PI phosphatases are also up or down regulated in several human cancers such as glioblastoma or breast cancer. Their cellular localization, that is dynamic and varies in response to stimuli, is an important issue to understand function. This is the case for two members of the PI 5-phosphatase SKIP and SHIP2. Both enzymes are in ruffles, plasma membranes, the endoplasmic reticulum, a situation that is unique for SKIP, and the nucleus. Following localization, PI 5-phosphatases act on specific cellular pools of PIs, which in turn interact with target proteins. Nuclear PIs have emerged as regulators of genome functions in different area of cell signaling. They often localize to nuclear speckles, as do several PI metabolizing kinases and phosphatases. We asked whether SKIP and SHIP2 could have an impact on nuclear PI(4,5)P2. In two glioblastoma cell models, lowering SKIP expression had an impact on nuclear PI(4,5)P2. In a model of SHIP2 deletion in MCF-7 cells, no change in nuclear PI(4,5)P2 was observed. Finally, we present evidence of an anti-tumoral role of SKIP in vivo, in xenografts using as model U87shSKIP cells.
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Affiliation(s)
- Ana Raquel Ramos
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Somadri Ghosh
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Tara Suhel
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Clément Chevalier
- Center for Microscopy and Molecular Imaging ULB, 12 Rue des Professeurs Jeener et Brachet, 6041, Charleroi, Belgium
| | - Eric Owusu Obeng
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium; Department of Biomedical Sciences, University of Bologna, Via Irnerio, 48, 40126, Bologna, Italy
| | - Bohumil Fafilek
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Pavel Krejci
- Department of Biology, Faculty of Medicine, Masaryk University, 62500, Brno, Czech Republic
| | - Benjamin Beck
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium
| | - Christophe Erneux
- IRIBHM, Campus Erasme, ULB Bâtiment C, 808 Route de Lennik, 1070, Bruxelles, Belgium.
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24
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Nuclear Phosphoinositides-Versatile Regulators of Genome Functions. Cells 2019; 8:cells8070649. [PMID: 31261688 PMCID: PMC6678639 DOI: 10.3390/cells8070649] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 06/21/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022] Open
Abstract
The many functions of phosphoinositides in cytosolic signaling were extensively studied; however, their activities in the cell nucleus are much less clear. In this review, we summarize data about their nuclear localization and metabolism, and review the available literature on their involvements in chromatin remodeling, gene transcription, and RNA processing. We discuss the molecular mechanisms via which nuclear phosphoinositides, in particular phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2), modulate nuclear processes. We focus on PI(4,5)P2’s role in the modulation of RNA polymerase I activity, and functions of the nuclear lipid islets—recently described nucleoplasmic PI(4,5)P2-rich compartment involved in RNA polymerase II transcription. In conclusion, the high impact of the phosphoinositide–protein complexes on nuclear organization and genome functions is only now emerging and deserves further thorough studies.
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25
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Nuclear Phosphoinositides: Their Regulation and Roles in Nuclear Functions. Int J Mol Sci 2019; 20:ijms20122991. [PMID: 31248120 PMCID: PMC6627530 DOI: 10.3390/ijms20122991] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/22/2019] [Accepted: 06/17/2019] [Indexed: 12/29/2022] Open
Abstract
Polyphosphoinositides (PPIns) are a family of seven lipid messengers that regulate a vast array of signalling pathways to control cell proliferation, migration, survival and differentiation. PPIns are differentially present in various sub-cellular compartments and, through the recruitment and regulation of specific proteins, are key regulators of compartment identity and function. Phosphoinositides and the enzymes that synthesise and degrade them are also present in the nuclear membrane and in nuclear membraneless compartments such as nuclear speckles. Here we discuss how PPIns in the nucleus are modulated in response to external cues and how they function to control downstream signalling. Finally we suggest a role for nuclear PPIns in liquid phase separations that are involved in the formation of membraneless compartments within the nucleus.
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26
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Polyphosphoinositides in the nucleus: Roadmap of their effectors and mechanisms of interaction. Adv Biol Regul 2019; 72:7-21. [PMID: 31003946 DOI: 10.1016/j.jbior.2019.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 01/01/2023]
Abstract
Biomolecular interactions between proteins and polyphosphoinositides (PPIn) are essential in the regulation of the vast majority of cellular processes. Consequently, alteration of these interactions is implicated in the development of many diseases. PPIn are phosphorylated derivatives of phosphatidylinositol and consist of seven species with different phosphate combinations. PPIn signal by recruiting proteins via canonical domains or short polybasic motifs. Although their actions are predominantly documented on cytoplasmic membranes, six of the seven PPIn are present within the nucleus together with the PPIn kinases, phosphatases and phospholipases that regulate their turnover. Importantly, the contribution of nuclear PPIn in the regulation of nuclear processes has led to an increased recognition of their importance compared to their more accepted cytoplasmic roles. This review summarises our knowledge on the identification and functional characterisation of nuclear PPIn-effector proteins as well as their mode of interactions, which tend to favour polybasic motifs.
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27
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Shakyawar DK, Muralikrishna B, Radha V. C3G dynamically associates with nuclear speckles and regulates mRNA splicing. Mol Biol Cell 2019; 29:1111-1124. [PMID: 29496966 PMCID: PMC5921577 DOI: 10.1091/mbc.e17-07-0442] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The first example of a Ras family GTPase and its exchange factor C3G localizing to nuclear speckles and regulating mRNA splicing is presented. C3G (Crk SH3 domain binding guanine nucleotide releasing factor) (Rap guanine nucleotide exchange factor 1), essential for mammalian embryonic development, is ubiquitously expressed and undergoes regulated nucleocytoplasmic exchange. Here we show that C3G localizes to SC35-positive nuclear speckles and regulates splicing activity. Reversible association of C3G with speckles was seen on inhibition of transcription and splicing. C3G shows partial colocalization with SC35 and is recruited to a chromatin and RNase-sensitive fraction of speckles. Its presence in speckles is dependent on intact cellular actin cytoskeleton and is lost on expression of the kinase Clk1. Rap1, a substrate of C3G, is also present in nuclear speckles, and inactivation of Rap signaling by expression of GFP-Rap1GAP alters speckle morphology and number. Enhanced association of C3G with speckles is seen on glycogen synthase kinase 3 beta inhibition or differentiation of C2C12 cells to myotubes. CRISPR/Cas9-mediated knockdown of C3G resulted in altered splicing activity of an artificial gene as well as endogenous CD44. C3G knockout clones of C2C12 as well as MDA-MB-231 cells showed reduced protein levels of several splicing factors compared with control cells. Our results identify C3G and Rap1 as novel components of nuclear speckles and a role for C3G in regulating cellular RNA splicing activity.
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Affiliation(s)
| | | | - Vegesna Radha
- Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
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28
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Hawse WF, Cattley RT. T cells transduce T-cell receptor signal strength by generating different phosphatidylinositols. J Biol Chem 2019; 294:4793-4805. [PMID: 30692200 DOI: 10.1074/jbc.ra118.006524] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/14/2019] [Indexed: 12/26/2022] Open
Abstract
T-cell receptor (TCR) signaling strength is a dominant factor regulating T-cell differentiation, thymic development, and cytokine signaling. The molecular mechanisms by which TCR signal strength is transduced to downstream signaling networks remains ill-defined. Using computational modeling, biochemical assays, and imaging flow cytometry, we found here that TCR signal strength differentially generates phosphatidylinositol species. Weak TCR signals generated elevated phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) and reduced phosphatidylinositol (3,4,5)-trisphosphate (PIP3) levels, whereas strong TCR signals reduced PI(4,5)P2 and elevated PIP3 levels. A proteomics screen revealed that focal adhesion kinase bound PI(4,5)P2, biochemical assays disclosed that focal adhesion kinase is preferentially activated by weak TCR signals and is required for optimal Treg induction, and further biochemical experiments revealed how TCR signaling strength regulates AKT activation. Low PIP3 levels generated by weak TCR signals were sufficient to activate phosphoinositide-dependent kinase-1 to phosphorylate AKT on Thr-308 but insufficient to activate mTOR complex 2 (mTORC2), whereas elevated PIP3 levels generated by a strong TCR signal were required to activate mTORC2 to phosphorylate Ser-473 on AKT. Our results provide support for a model that links TCR signaling to mTORC2 activation via phosphoinositide 3-kinase signaling. Together, the findings in this work establish that T cells measure TCR signal strength by generating different levels of phosphatidylinositol species that engage alternate signaling networks to control cell fate decisions.
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Affiliation(s)
- William F Hawse
- From the Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Richard T Cattley
- From the Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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29
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Marx B, Hufbauer M, Zigrino P, Majewski S, Markiefka B, Sachsenheimer T, Brügger B, Akgül B. Phospholipidation of nuclear proteins by the human papillomavirus E6 oncoprotein: implication in carcinogenesis. Oncotarget 2018; 9:34142-34158. [PMID: 30344928 PMCID: PMC6183346 DOI: 10.18632/oncotarget.26140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 09/06/2018] [Indexed: 12/16/2022] Open
Abstract
Phospholipids regulate numerous cellular functions and their deregulation is known to be associated with cancer development. Here, we show for the first time that expression of the E6 oncoprotein of human papillomavirus type 8 (HPV8) leads to a profound increase in nuclear phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) lipid levels in monolayer cultures, that led to an aberrant phospholipidation of cellular proteins. Elevated PI(4,5)P2 levels in organotypic skin cultures, skin tumors of K14-HPV8-E6 transgenic mice as well as HPV8 positive skin carcinomas highly suggest a decisive role of PI(4,5)P2 in HPV associated squamous-cell-carcinoma development. Furthermore, mass-spectrometric analysis confirmed an increase of PI(4,5)P2, which was characterized by a shift in the distribution of lipid species. PI(4,5)P2 upregulation was independent of E6 interference with MAML1. However, E6 does interfere with the PI(4,5)P2 metabolic pathway by upregulation of phosphatidylinositol-4-phosphate-5-kinase type I and phosphatidylinositol-5-phosphate 4-kinase type II as well as the binding to 5'-phosphatase OCRL and phosphatidylinositol. All of these mechanisms combined may contribute to PI(4,5)P2 elevation in E6 positive cells. The identification of CAND1 and SND1 - two proteins known to be involved in carcinogenic processes - were significantly stronger phospholipidized in the presence of E6. In conclusion we provide evidence that the modulation of the PI(4,5)P2 metabolism is a novel oncogenic mechanism relevant for HPV-induced carcinogenesis.
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Affiliation(s)
- Benjamin Marx
- Institute of Virology, University of Cologne, Cologne, Germany
| | - Martin Hufbauer
- Institute of Virology, University of Cologne, Cologne, Germany
| | - Paola Zigrino
- Department of Dermatology and Venereology, University Hospital Cologne, Cologne, Germany
| | - Slawomir Majewski
- Department of Dermatology and Venereology, Medical University of Warsaw, Warsaw, Poland
| | - Birgid Markiefka
- Institute of Pathology, University Hospital Cologne, Cologne, Germany
| | | | - Britta Brügger
- Heidelberg University Biochemistry Center (BZH), Heidelberg, Germany
| | - Baki Akgül
- Institute of Virology, University of Cologne, Cologne, Germany
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30
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Sztacho M, Sobol M, Balaban C, Escudeiro Lopes SE, Hozák P. Nuclear phosphoinositides and phase separation: Important players in nuclear compartmentalization. Adv Biol Regul 2018; 71:111-117. [PMID: 30249540 DOI: 10.1016/j.jbior.2018.09.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/14/2018] [Accepted: 09/15/2018] [Indexed: 02/08/2023]
Abstract
Nuclear phosphoinositides are recognized as regulators of many nuclear processes including chromatin remodeling, splicing, transcription, DNA repair and epigenetics. These processes are spatially organized in different nuclear compartments. Phase separation is involved in the formation of various nuclear compartments and molecular condensates separated from surrounding environment. The surface of such structures spatiotemporally coordinates formation of protein complexes. PI(4,5)P2 (PIP2) integration into phase-separated structures might provide an additional step in their spatial diversification by attracting certain proteins with affinity to PIP2. Our laboratory has recently identified novel membrane-free PIP2-containing structures, so called Nuclear Lipid Islets (NLIs). We provide an evidence that these structures are evolutionary conserved in different organisms. We hypothesize that NLIs serve as a scaffolding platform which facilitates the formation of transcription factories, thus participating in the formation of nuclear architecture competent for transcription. In this review we speculate on a possible role of NLIs in the integration of various processes linked to RNAPII transcription, chromatin remodeling, actin-myosin interaction, alternative splicing and lamin structures.
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Affiliation(s)
- Martin Sztacho
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., 142 20, Prague, Czech Republic
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., 142 20, Prague, Czech Republic
| | - Can Balaban
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., 142 20, Prague, Czech Republic
| | - Sara Eliana Escudeiro Lopes
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., 142 20, Prague, Czech Republic
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., 142 20, Prague, Czech Republic; Department of Epigenetics of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., division BIOCEV, 25250, Vestec, Czech Republic; Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., 142 20, Prague, Czech Republic.
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31
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Ulicna L, Rohozkova J, Hozak P. Multiple Aspects of PIP2 Involvement in C. elegans Gametogenesis. Int J Mol Sci 2018; 19:ijms19092679. [PMID: 30201859 PMCID: PMC6163852 DOI: 10.3390/ijms19092679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 08/28/2018] [Accepted: 09/05/2018] [Indexed: 12/20/2022] Open
Abstract
One of the most studied phosphoinositides is phosphatidylinositol 4,5-bisphosphate (PIP2), which localizes to the plasma membrane, nuclear speckles, small foci in the nucleoplasm, and to the nucleolus in mammalian cells. Here, we show that PIP2 also localizes to the nucleus in prophase I, during the gametogenesis of C. elegans hermaphrodite. The depletion of PIP2 by type I PIP kinase (PPK-1) kinase RNA interference results in an altered chromosome structure and leads to various defects during meiotic progression. We observed a decreased brood size and aneuploidy in progeny, defects in synapsis, and crossover formation. The altered chromosome structure is reflected in the increased transcription activity of a tightly regulated process in prophase I. To elucidate the involvement of PIP2 in the processes during the C. elegans development, we identified the PIP2-binding partners, leucine-rich repeat (LRR-1) protein and proteasome subunit beta 4 (PBS-4), pointing to its involvement in the ubiquitin–proteasome pathway.
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Affiliation(s)
- Livia Ulicna
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Prague 142 20, Czech Republic.
| | - Jana Rohozkova
- Department of Epigenetics of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Division BIOCEV, Vestec 252 50, Czech Republic.
| | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Prague 142 20, Czech Republic.
- Department of Epigenetics of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Division BIOCEV, Vestec 252 50, Czech Republic.
- Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, v.v.i., Prague 142 20, Czech Republic.
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32
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Bryant JM, Blind RD. Signaling through non-membrane nuclear phosphoinositide binding proteins in human health and disease. J Lipid Res 2018; 60:299-311. [PMID: 30201631 DOI: 10.1194/jlr.r088518] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 08/22/2018] [Indexed: 12/22/2022] Open
Abstract
Phosphoinositide membrane signaling is critical for normal physiology, playing well-known roles in diverse human pathologies. The basic mechanisms governing phosphoinositide signaling within the nucleus, however, have remained deeply enigmatic owing to their presence outside the nuclear membranes. Over 40% of nuclear phosphoinositides can exist in this non-membrane state, held soluble in the nucleoplasm by nuclear proteins that remain largely unidentified. Recently, two nuclear proteins responsible for solubilizing phosphoinositides were identified, steroidogenic factor-1 (SF-1; NR5A1) and liver receptor homolog-1 (LRH-1; NR5A2), along with two enzymes that directly remodel these phosphoinositide/protein complexes, phosphatase and tensin homolog (PTEN; MMAC) and inositol polyphosphate multikinase (IPMK; ipk2). These new footholds now permit the assignment of physiological functions for nuclear phosphoinositides in human diseases, such as endometriosis, nonalcoholic fatty liver disease/steatohepatitis, glioblastoma, and hepatocellular carcinoma. The unique nature of nuclear phosphoinositide signaling affords extraordinary clinical opportunities for new biomarkers, diagnostics, and therapeutics. Thus, phosphoinositide biology within the nucleus may represent the next generation of low-hanging fruit for new drugs, not unlike what has occurred for membrane phosphatidylinositol 3-kinase drug development. This review connects recent basic science discoveries in nuclear phosphoinositide signaling to clinical pathologies, with the hope of inspiring development of new therapies.
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Affiliation(s)
- Jamal M Bryant
- Departments of Pharmacology, Biochemistry, and Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Raymond D Blind
- Departments of Pharmacology, Biochemistry, and Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN 37232
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33
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Phospholipids and inositol phosphates linked to the epigenome. Histochem Cell Biol 2018; 150:245-253. [DOI: 10.1007/s00418-018-1690-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2018] [Indexed: 12/17/2022]
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34
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Sobol M, Krausová A, Yildirim S, Kalasová I, Fáberová V, Vrkoslav V, Philimonenko V, Marášek P, Pastorek L, Čapek M, Lubovská Z, Uličná L, Tsuji T, Lísa M, Cvačka J, Fujimoto T, Hozak P. Nuclear phosphatidylinositol 4,5-bisphosphate islets contribute to efficient RNA polymerase II-dependent transcription. J Cell Sci 2018; 131:jcs.211094. [PMID: 29507116 DOI: 10.1242/jcs.211094] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 02/22/2018] [Indexed: 12/18/2022] Open
Abstract
This paper describes a novel type of nuclear structure - nuclear lipid islets (NLIs). They are of 40-100 nm with a lipidic interior, and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] molecules comprise a significant part of their surface. Most of NLIs have RNA at the periphery. Consistent with that, RNA is required for their integrity. The NLI periphery is associated with Pol II transcription machinery, including the largest Pol II subunit, transcription factors and NM1 (also known as NMI). The PtdIns(4,5)P2-NM1 interaction is important for Pol II transcription, since NM1 knockdown reduces the Pol II transcription level, and the overexpression of wild-type NM1 [but not NM1 mutated in the PtdIns(4,5)P2-binding site] rescues the transcription. Importantly, Pol II transcription is dependent on NLI integrity, because an enzymatic reduction of the PtdIns(4,5)P2 level results in a decrease of the Pol II transcription level. Furthermore, about half of nascent transcripts localise to NLIs, and transcriptionally active transgene loci preferentially colocalise with NLIs. We hypothesize that NLIs serve as a structural platform that facilitates the formation of Pol II transcription factories, thus participating in the formation of nuclear architecture competent for transcription.
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Affiliation(s)
- Margarita Sobol
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Alžběta Krausová
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Sukriye Yildirim
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Ilona Kalasová
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Veronika Fáberová
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Vladimír Vrkoslav
- Institute of Organic Chemistry and Biochemistry, CAS, v.v.i., Research Service Group of Mass Spectrometry, Flemingovo náměstí 2, 166 10, Prague 6, Czech Republic
| | - Vlada Philimonenko
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic.,Institute of Molecular Genetics, CAS, v.v.i., Electron Microscopy Core Facility, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Pavel Marášek
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Lukáš Pastorek
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic.,Institute of Molecular Genetics, CAS, v.v.i., Electron Microscopy Core Facility, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Martin Čapek
- Institute of Molecular Genetics, CAS, v.v.i., Light Microscopy Core Facility, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Zuzana Lubovská
- Institute of Molecular Genetics, CAS, v.v.i., Electron Microscopy Core Facility, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Lívia Uličná
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Takuma Tsuji
- Nagoya University Graduate School of Medicine, Department of Molecular Cell Biology, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Miroslav Lísa
- University of Pardubice, Faculty of Chemical Technology, Department of Analytical Chemistry, Studentská 573, 532 10, Pardubice, Czech Republic
| | - Josef Cvačka
- Institute of Organic Chemistry and Biochemistry, CAS, v.v.i., Research Service Group of Mass Spectrometry, Flemingovo náměstí 2, 166 10, Prague 6, Czech Republic
| | - Toyoshi Fujimoto
- Nagoya University Graduate School of Medicine, Department of Molecular Cell Biology, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Pavel Hozak
- Institute of Molecular Genetics, CAS, v.v.i., Department of Biology of the Cell Nucleus, Vídeňská 1083, 142 20, Prague 4, Czech Republic .,Institute of Molecular Genetics, CAS, v.v.i., Division BIOCEV, Laboratory of Epigenetics of the Cell Nucleus, Průmyslová 595, 252 50, Vestec, Czech Republic.,Institute of Molecular Genetics, CAS, v.v.i., Microscopy Centre, Vídeňská 1083, 142 20, Prague 4, Czech Republic
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35
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PIP2 epigenetically represses rRNA genes transcription interacting with PHF8. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:266-275. [DOI: 10.1016/j.bbalip.2017.12.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/05/2017] [Accepted: 12/09/2017] [Indexed: 02/01/2023]
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36
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Nevzorov I, Sidorenko E, Wang W, Zhao H, Vartiainen MK. Myosin-1C uses a novel phosphoinositide-dependent pathway for nuclear localization. EMBO Rep 2018; 19:290-304. [PMID: 29330316 PMCID: PMC5797967 DOI: 10.15252/embr.201744296] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 12/05/2017] [Accepted: 12/11/2017] [Indexed: 01/07/2023] Open
Abstract
Accurate control of macromolecule transport between nucleus and cytoplasm underlines several essential biological processes, including gene expression. According to the canonical model, nuclear import of soluble proteins is based on nuclear localization signals and transport factors. We challenge this view by showing that nuclear localization of the actin-dependent motor protein Myosin-1C (Myo1C) resembles the diffusion-retention mechanism utilized by inner nuclear membrane proteins. We show that Myo1C constantly shuttles in and out of the nucleus and that its nuclear localization does not require soluble factors, but is dependent on phosphoinositide binding. Nuclear import of Myo1C is preceded by its interaction with the endoplasmic reticulum, and phosphoinositide binding is specifically required for nuclear import, but not nuclear retention, of Myo1C. Our results therefore demonstrate, for the first time, that membrane association and binding to nuclear partners is sufficient to drive nuclear localization of also soluble proteins, opening new perspectives to evolution of cellular protein sorting mechanisms.
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Affiliation(s)
- Ilja Nevzorov
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ekaterina Sidorenko
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Weihuan Wang
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
- College of Life Sciences, Northwest A&F University, Yangling, Shanxi, China
| | - Hongxia Zhao
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Maria K Vartiainen
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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37
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Ratti S, Ramazzotti G, Faenza I, Fiume R, Mongiorgi S, Billi AM, McCubrey JA, Suh PG, Manzoli L, Cocco L, Follo MY. Nuclear inositide signaling and cell cycle. Adv Biol Regul 2018; 67:1-6. [PMID: 29102395 DOI: 10.1016/j.jbior.2017.10.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 06/07/2023]
Abstract
Phosphatidylinositols (PIs) are responsible for several signaling pathways related to many cellular functions, such as cell cycle regulation at different check-points, cell proliferation, cell differentiation, membrane trafficking and gene expression. PI metabolism is not only present at the cytoplasmic level, but also at the nuclear one, where different signaling pathways affect essential nuclear mechanisms in eukaryotic cells. In this review we focus on nuclear inositide signaling in relation to cell cycle regulation. Many evidences underline the pivotal role of nuclear inositide signaling in cell cycle regulation and cell proliferation associated to different strategic physiopathological mechanisms in several cell systems and diseases.
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Affiliation(s)
- Stefano Ratti
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy.
| | - Giulia Ramazzotti
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Irene Faenza
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Roberta Fiume
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Sara Mongiorgi
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Anna Maria Billi
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - James A McCubrey
- Department of Microbiology and Immunology, Brody School of Medicine, MS#629, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Lucia Manzoli
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Lucio Cocco
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
| | - Matilde Y Follo
- Cellular Signalling Laboratory Department of Biomedical Sciences, University of Bologna, Via Irnerio 48, 40126 Bologna, Italy
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38
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DNA damage causes rapid accumulation of phosphoinositides for ATR signaling. Nat Commun 2017; 8:2118. [PMID: 29242514 PMCID: PMC5730617 DOI: 10.1038/s41467-017-01805-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 10/13/2017] [Indexed: 12/11/2022] Open
Abstract
Phosphoinositide lipids (PPIs) are enriched in the nucleus and are accumulated at DNA damage sites. Here, we investigate roles of nuclear PPIs in DNA damage response by sequestering specific PPIs with the expression of nuclear-targeted PH domains, which inhibits recruitment of Ataxia telangiectasia and Rad3-related protein (ATR) and reduces activation of Chk1. PPI-binding domains rapidly (< 1 s) accumulate at damage sites with local enrichment of PPIs. Accumulation of PIP3 in complex with the nuclear receptor protein, SF1, at damage sites requires phosphorylation by inositol polyphosphate multikinase (IPMK) and promotes nuclear actin assembly that is required for ATR recruitment. Suppressed ATR recruitment/activation is confirmed with latrunculin A and wortmannin treatment as well as IPMK or SF1 depletion. Other DNA repair pathways involving ATM and DNA-PKcs are unaffected by PPI sequestration. Together, these findings reveal that nuclear PPI metabolism mediates an early damage response through the IPMK-dependent pathway to specifically recruit ATR. Phosphoinositides are enriched in the nucleus and accumulate upon DNA damage but their role in responding to DNA damage is poorly defined. Here, the authors show that phosphoinositides rapidly accumulate at DNA damage sites and are required for ATR recruitment and subsequent Chk1 activation.
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39
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Hamann BL, Blind RD. Nuclear phosphoinositide regulation of chromatin. J Cell Physiol 2017; 233:107-123. [PMID: 28256711 DOI: 10.1002/jcp.25886] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 12/26/2022]
Abstract
Phospholipid signaling has clear connections to a wide array of cellular processes, particularly in gene expression and in controlling the chromatin biology of cells. However, most of the work elucidating how phospholipid signaling pathways contribute to cellular physiology have studied cytoplasmic membranes, while relatively little attention has been paid to the role of phospholipid signaling in the nucleus. Recent work from several labs has shown that nuclear phospholipid signaling can have important roles that are specific to this cellular compartment. This review focuses on the nuclear phospholipid functions and the activities of phospholipid signaling enzymes that regulate metazoan chromatin and gene expression. In particular, we highlight the roles that nuclear phosphoinositides play in several nuclear-driven physiological processes, such as differentiation, proliferation, and gene expression. Taken together, the recent discovery of several specifically nuclear phospholipid functions could have dramatic impact on our understanding of the fundamental mechanisms that enable tight control of cellular physiology.
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Affiliation(s)
- Bree L Hamann
- Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Raymond D Blind
- Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee.,Departments of Medicine, Biochemistry and Pharmacology, Division of Diabetes Endocrinology and Metabolism, The Vanderbilt Diabetes Research and Training Center and the Vanderbilt-Ingram Cancer Center, Nashville, Tennessee
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40
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Ratti S, Mongiorgi S, Ramazzotti G, Follo MY, Mariani GA, Suh PG, McCubrey JA, Cocco L, Manzoli L. Nuclear Inositide Signaling Via Phospholipase C. J Cell Biochem 2017; 118:1969-1978. [PMID: 28106288 DOI: 10.1002/jcb.25894] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 12/22/2022]
Abstract
The existence of an independent nuclear inositide pathway distinct from the cytoplasmic one has been demonstrated in different physiological systems and in diseases. In this prospect we analyze the role of PI-PLCβ1 nuclear isoform in relation to the cell cycle regulation, the cell differentiation, and different physiopathological pathways focusing on the importance of the nuclear localization from both molecular and clinical point of view. PI-PLCβ1 is essential for G1/S transition through DAG and Cyclin D3 and plays also a central role in G2/M progression through Cyclin B1 and PKCα. In the differentiation process of C2C12 cells PI-PLCβ1 increases in both myogenic differentiation and osteogenic differentiation. PI-PLCβ1 and Cyclin D3 reduction has been observed in Myotonic Dystrophy (DM) suggesting a pivotal role of these enzymes in DM physiopathology. PI-PLCβ1 is also involved in adipogenesis through a double phase mechanism. Moreover, PI-PLCβ1 plays a key role in the normal hematopoietic differentiation where it seems to decrease in erythroid differentiation and increase in myeloid differentiation. In Myelodysplastic Syndromes (MDS) PI-PLCβ1 has a genetic and epigenetic relevance and it is related to MDS patients' risk of Acute Myeloid Leukemia (AML) evolution. In MDS patients PI-PLCβ1 seems to be also a therapeutic predictive outcome marker. In the central nervous system, PI-PLCβ1 seems to be involved in different pathways in both brain cortex development and synaptic plasticity related to different diseases. Another PI-PLC isozyme that could be related to nuclear activities is PI-PLCζ that is involved in infertility processes. J. Cell. Biochem. 118: 1969-1978, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Stefano Ratti
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Sara Mongiorgi
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Giulia Ramazzotti
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Matilde Y Follo
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Giulia A Mariani
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Pann-Ghill Suh
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - James A McCubrey
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville 27834, North Carolina
| | - Lucio Cocco
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
| | - Lucia Manzoli
- Cellular Signalling Laboratory, Department of Biomedical and Neuromotor Sciences, University of Bologna, via Irnerio 48, 40126 Bologna, Italy
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41
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De Craene JO, Bertazzi DL, Bär S, Friant S. Phosphoinositides, Major Actors in Membrane Trafficking and Lipid Signaling Pathways. Int J Mol Sci 2017; 18:ijms18030634. [PMID: 28294977 PMCID: PMC5372647 DOI: 10.3390/ijms18030634] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/02/2017] [Accepted: 03/06/2017] [Indexed: 11/30/2022] Open
Abstract
Phosphoinositides are lipids involved in the vesicular transport of proteins and lipids between the different compartments of eukaryotic cells. They act by recruiting and/or activating effector proteins and thus are involved in regulating various cellular functions, such as vesicular budding, membrane fusion and cytoskeleton dynamics. Although detected in small concentrations in membranes, their role is essential to cell function, since imbalance in their concentrations is a hallmark of many cancers. Their synthesis involves phosphorylating/dephosphorylating positions D3, D4 and/or D5 of their inositol ring by specific lipid kinases and phosphatases. This process is tightly regulated and specific to the different intracellular membranes. Most enzymes involved in phosphoinositide synthesis are conserved between yeast and human, and their loss of function leads to severe diseases (cancer, myopathy, neuropathy and ciliopathy).
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Affiliation(s)
- Johan-Owen De Craene
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
| | - Dimitri L Bertazzi
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
| | - Séverine Bär
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
| | - Sylvie Friant
- Department of Molecular and Cellular Genetics, Université de Strasbourg, CNRS, GMGM UMR 7156, F-67000 Strasbourg, France.
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42
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Rodriguez-Corona U, Pereira-Santana A, Sobol M, Rodriguez-Zapata LC, Hozak P, Castano E. Novel Ribonuclease Activity Differs between Fibrillarins from Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2017; 8:1878. [PMID: 29163603 PMCID: PMC5674935 DOI: 10.3389/fpls.2017.01878] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 10/16/2017] [Indexed: 05/09/2023]
Abstract
Fibrillarin is one of the most important nucleolar proteins that have been shown as essential for life. Fibrillarin localizes primarily at the periphery between fibrillar center and dense fibrillar component as well as in Cajal bodies. In most plants there are at least two different genes for fibrillarin. In Arabidopsis thaliana both genes show high level of expression in transcriptionally active cells. Here, we focus on two important differences between A. thaliana fibrillarins. First and most relevant is the enzymatic activity by AtFib2. The AtFib2 shows a novel ribonuclease activity that is not seen with AtFib1. Second is a difference in the ability to interact with phosphoinositides and phosphatidic acid between both proteins. We also show that the novel ribonuclease activity as well as the phospholipid binding region of fibrillarin is confine to the GAR domain. The ribonuclease activity of fibrillarin reveals in this study represents a new role for this protein in rRNA processing.
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Affiliation(s)
- Ulises Rodriguez-Corona
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Mexico
| | - Alejandro Pereira-Santana
- Biosystematics Group, Department of Plant Sciences, Wageningen University and Research, Wageningen, Netherlands
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czechia
| | | | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Enrique Castano
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, Mérida, Mexico
- *Correspondence: Enrique Castano,
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43
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Pastorek L, Sobol M, Hozák P. Colocalization coefficients evaluating the distribution of molecular targets in microscopy methods based on pointed patterns. Histochem Cell Biol 2016; 146:391-406. [PMID: 27460592 PMCID: PMC5037163 DOI: 10.1007/s00418-016-1467-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 01/28/2023]
Abstract
In biomedical studies, the colocalization is commonly understood as the overlap between distinctive labelings in images. This term is usually associated especially with quantitative evaluation of the immunostaining in fluorescence microscopy. On the other hand, the evaluation of the immunolabeling colocalization in the electron microscopy images is still under-investigated and biased by the subjective and non-quantitative interpretation of the image data. We introduce a novel computational technique for quantifying the level of colocalization in pointed patterns. Our approach follows the idea included in the widely used Manders' colocalization coefficients in fluorescence microscopy and represents its counterpart for electron microscopy. In presented methodology, colocalization is understood as the product of the spatial interactions at the single-particle (single-molecule) level. Our approach extends the current significance testing in the immunoelectron microscopy images and establishes the descriptive colocalization coefficients. To demonstrate the performance of the proposed coefficients, we investigated the level of spatial interactions of phosphatidylinositol 4,5-bisphosphate with fibrillarin in nucleoli. We compared the electron microscopy colocalization coefficients with Manders' colocalization coefficients for confocal microscopy and super-resolution structured illumination microscopy. The similar tendency of the values obtained using different colocalization approaches suggests the biological validity of the scientific conclusions. The presented methodology represents a good basis for further development of the quantitative analysis of immunoelectron microscopy data and can be used for studying molecular interactions at the ultrastructural level. Moreover, this methodology can be applied also to the other super-resolution microscopy techniques focused on characterization of discrete pointed structures.
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Affiliation(s)
- Lukáš Pastorek
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
- Microscopy Centre, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
- Microscopy Centre, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic.
- Microscopy Centre, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic.
- Laboratory of Epigenetics of the Cell Nucleus, Division BIOCEV, Institute of Molecular Genetics of the ASCR v. v. i., Průmyslová 595, 252 50, Vestec, Czech Republic.
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44
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A polybasic motif in ErbB3-binding protein 1 (EBP1) has key functions in nucleolar localization and polyphosphoinositide interaction. Biochem J 2016; 473:2033-47. [PMID: 27118868 PMCID: PMC4941749 DOI: 10.1042/bcj20160274] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 04/26/2016] [Indexed: 12/29/2022]
Abstract
We reveal the identification of a polybasic motif necessary for polyphosphoinositide interaction and nucleolar targeting of ErbB3 binding protein 1 (EBP1). EBP1 interacts directly with phosphatidylinositol(3,4,5)-triphosphate and their association is detected in the nucleolus, implying regulatory roles of nucleolar processes. Polyphosphoinositides (PPIns) are present in the nucleus where they participate in crucial nuclear processes, such as chromatin remodelling, transcription and mRNA processing. In a previous interactomics study, aimed to gain further insight into nuclear PPIns functions, we identified ErbB3 binding protein 1 (EBP1) as a potential nuclear PPIn-binding protein in a lipid pull-down screen. EBP1 is a ubiquitous and conserved protein, located in both the cytoplasm and nucleolus, and associated with cell proliferation and survival. In the present study, we show that EBP1 binds directly to several PPIns via two distinct PPIn-binding sites consisting of clusters of lysine residues and positioned at the N- and C-termini of the protein. Using interaction mutants, we show that the C-terminal PPIn-binding motif contributes the most to the localization of EBP1 in the nucleolus. Importantly, a K372N point mutation, located within the C-terminal motif and found in endometrial tumours, is sufficient to alter the nucleolar targeting of EBP1. Our study reveals also the presence of the class I phosphoinositide 3-kinase (PI3K) catalytic subunit p110β and its product PtdIns(3,4,5)P3 together with EBP1 in the nucleolus. Using NMR, we further demonstrate an association between EBP1 and PtdIns(3,4,5)P3 via both electrostatic and hydrophobic interactions. Taken together, these results show that EBP1 interacts directly with PPIns and associate with PtdIns(3,4,5)P3 in the nucleolus. The presence of p110β and PtdIns(3,4,5)P3 in the nucleolus indicates their potential role in regulating nucleolar processes, at least via EBP1.
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45
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Tools for visualization of phosphoinositides in the cell nucleus. Histochem Cell Biol 2016; 145:485-96. [DOI: 10.1007/s00418-016-1409-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2016] [Indexed: 01/09/2023]
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46
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Poli A, Billi AM, Mongiorgi S, Ratti S, McCubrey JA, Suh PG, Cocco L, Ramazzotti G. Nuclear Phosphatidylinositol Signaling: Focus on Phosphatidylinositol Phosphate Kinases and Phospholipases C. J Cell Physiol 2015; 231:1645-55. [DOI: 10.1002/jcp.25273] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 12/01/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Alessandro Poli
- Department of Biomedical Sciences; University of Bologna; Bologna Italy
| | - Anna Maria Billi
- Department of Biomedical Sciences; University of Bologna; Bologna Italy
| | - Sara Mongiorgi
- Department of Biomedical Sciences; University of Bologna; Bologna Italy
| | - Stefano Ratti
- Department of Biomedical Sciences; University of Bologna; Bologna Italy
| | - James A. McCubrey
- Department of Microbiology and Immunology; Brody School of Medicine; East Carolina University; Greenville North Carolina
| | - Pann-Ghill Suh
- School of Life Sciences; Ulsan National Institute of Science and Technology; Ulsan Republic of Korea
| | - Lucio Cocco
- Department of Biomedical Sciences; University of Bologna; Bologna Italy
| | - Giulia Ramazzotti
- Department of Biomedical Sciences; University of Bologna; Bologna Italy
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47
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Grindheim AK, Hollås H, Raddum AM, Saraste J, Vedeler A. Reactive oxygen species exert opposite effects on Tyr23 phosphorylation of the nuclear and cortical pools of annexin A2. J Cell Sci 2015; 129:314-28. [PMID: 26644180 PMCID: PMC4732284 DOI: 10.1242/jcs.173195] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 11/27/2015] [Indexed: 01/09/2023] Open
Abstract
Annexin A2 (AnxA2) is a multi-functional and -compartmental protein whose subcellular localisation and functions are tightly regulated by its post-translational modifications. AnxA2 and its Tyr23-phosphorylated form (pTyr23AnxA2) are involved in malignant cell transformation, metastasis and angiogenesis. Here, we show that H2O2 exerts rapid, simultaneous and opposite effects on the Tyr23 phosphorylation status of AnxA2 in two distinct compartments of rat pheochromocytoma (PC12) cells. Reactive oxygen species induce dephosphorylation of pTyr23AnxA2 located in the PML bodies of the nucleus, whereas AnxA2 associated with F-actin at the cell cortex is Tyr23 phosphorylated. The H2O2-induced responses in both compartments are transient and the pTyr23AnxA2 accumulating at the cell cortex is subsequently incorporated into vesicles and then released to the extracellular space. Blocking nuclear export by leptomycin B does not affect the nuclear pool of pTyr23AnxA2, but increases the amount of total AnxA2 in this compartment, indicating that the protein might have several functions in the nucleus. These results suggest that Tyr23 phosphorylation can regulate the function of AnxA2 at distinct subcellular sites. Summary: Reactive oxygen species cause two opposite and transient Tyr23-based modifications of annexin A2; its dephosphorylation in the nucleus and phosphorylation at the cell cortex, resulting in release of the protein in exosomes.
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Affiliation(s)
- Ann Kari Grindheim
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway Molecular Imaging Center (MIC), University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway
| | - Hanne Hollås
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway
| | - Aase M Raddum
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway
| | - Jaakko Saraste
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway Molecular Imaging Center (MIC), University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway
| | - Anni Vedeler
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, Bergen N-5009, Norway
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48
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Loza-Muller L, Rodríguez-Corona U, Sobol M, Rodríguez-Zapata LC, Hozak P, Castano E. Fibrillarin methylates H2A in RNA polymerase I trans-active promoters in Brassica oleracea. FRONTIERS IN PLANT SCIENCE 2015; 6:976. [PMID: 26594224 PMCID: PMC4635213 DOI: 10.3389/fpls.2015.00976] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/26/2015] [Indexed: 05/24/2023]
Abstract
Fibrillarin is a well conserved methyltransferase involved in several if not all of the more than 100 methylations sites in rRNA which are essential for proper ribosome function. It is mainly localized in the nucleoli and Cajal bodies inside the cell nucleus where it exerts most of its functions. In plants, fibrillarin binds directly the guide RNA together with Nop56, Nop58, and 15.5ka proteins to form a snoRNP complex that selects the sites to be methylated in pre-processing of ribosomal RNA. Recently, the yeast counterpart NOP1 was found to methylate histone H2A in the nucleolar regions. Here we show that plant fibrillarin can also methylate histone H2A. In Brassica floral meristem cells the methylated histone H2A is mainly localized in the nucleolus but unlike yeast or human cells it also localize in the periphery of the nucleus. In specialized transport cells the pattern is altered and it exhibits a more diffuse staining in the nucleus for methylated histone H2A as well as for fibrillarin. Here we also show that plant fibrillarin is capable of interacting with H2A and carry out its methylation in the rDNA promoter.
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Affiliation(s)
- Lloyd Loza-Muller
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico
| | - Ulises Rodríguez-Corona
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, v.v.i.Prague, Czech Republic
| | | | - Pavel Hozak
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Academy of Sciences of the Czech Republic, v.v.i.Prague, Czech Republic
| | - Enrique Castano
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de YucatánMérida, Mexico
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Ji C, Zhang Y, Xu P, Xu T, Lou X. Nanoscale Landscape of Phosphoinositides Revealed by Specific Pleckstrin Homology (PH) Domains Using Single-molecule Superresolution Imaging in the Plasma Membrane. J Biol Chem 2015; 290:26978-26993. [PMID: 26396197 DOI: 10.1074/jbc.m115.663013] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 11/06/2022] Open
Abstract
Both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) are independent plasma membrane (PM) determinant lipids that are essential for multiple cellular functions. However, their nanoscale spatial organization in the PM remains elusive. Using single-molecule superresolution microscopy and new photoactivatable fluorescence probes on the basis of pleckstrin homology domains that specifically recognize phosphatidylinositides in insulin-secreting INS-1 cells, we report that the PI(4,5)P2 probes exhibited a remarkably uniform distribution in the major regions of the PM, with some sparse PI(4,5)P2-enriched membrane patches/domains of diverse sizes (383 ± 14 nm on average). Quantitative analysis revealed a modest concentration gradient that was much less steep than previously thought, and no densely packed PI(4,5)P2 nanodomains were observed. Live-cell superresolution imaging further demonstrated the dynamic structural changes of those domains in the flat PM and membrane protrusions. PI4P and phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P3) showed similar spatial distributions as PI(4,5)P2. These data reveal the nanoscale landscape of key inositol phospholipids in the native PM and imply a framework for local cellular signaling and lipid-protein interactions at a nanometer scale.
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Affiliation(s)
- Chen Ji
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and
| | - Yongdeng Zhang
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Tao Xu
- the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuelin Lou
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and.
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50
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Wickramasinghe VO, Laskey RA. Control of mammalian gene expression by selective mRNA export. Nat Rev Mol Cell Biol 2015; 16:431-42. [PMID: 26081607 DOI: 10.1038/nrm4010] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nuclear export of mRNAs is a crucial step in the regulation of gene expression, linking transcription in the nucleus to translation in the cytoplasm. Although important components of the mRNA export machinery are well characterized, such as transcription-export complexes TREX and TREX-2, recent work has shown that, in some instances, mammalian mRNA export can be selective and can regulate crucial biological processes such as DNA repair, gene expression, maintenance of pluripotency, haematopoiesis, proliferation and cell survival. Such findings show that mRNA export is an unexpected, yet potentially important, mechanism for the control of gene expression and of the mammalian transcriptome.
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Affiliation(s)
- Vihandha O Wickramasinghe
- Medical Research Centre (MRC) Cancer Unit, Hutchison/MRC Research Centre, Box 197, Biomedical Campus, Cambridge CB2 0XZ, UK
| | - Ronald A Laskey
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
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