1
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Liu ML, Lyu X, Werth VP. Recent progress in the mechanistic understanding of NET formation in neutrophils. FEBS J 2022; 289:3954-3966. [PMID: 34042290 PMCID: PMC9107956 DOI: 10.1111/febs.16036] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 05/11/2021] [Accepted: 05/24/2021] [Indexed: 01/03/2023]
Abstract
Neutrophils are the most abundant circulating white blood cells and one of the major cell types of the innate immune system. Neutrophil extracellular traps (NETs) are a result of the extracellular release of nuclear chromatin from the ruptured nuclear envelope and plasma membrane. The externalized chromatin is an ancient defense weapon for animals to entrap and kill microorganisms in the extracellular milieu, thus protecting animals ranging from lower invertebrates to higher vertebrates. Although the externalized chromatin has the advantage of acting as anti-infective to protect against infections, extracellular chromatin might be problematic in higher vertebrate animals as they have an adaptive immune system that can trigger further immune or autoimmune responses. NETs and their associated nuclear and/or cytoplasmic components may induce sterile inflammation, immune, and autoimmune responses, leading to various human diseases. Though important in human pathophysiology, the cellular and molecular mechanisms of NET formation (also called NETosis) are not well understood. Given that nuclear chromatin forms the backbone of NETs, the nucleus is the root of the nuclear DNA extracellular traps. Thus, nuclear chromatin decondensation, along with the rupture of nuclear envelope and plasma membrane, is required for nuclear chromatin extracellular release and NET formation. So far, most of the literature focuses on certain signaling pathways, which are involved in NET formation but without explanation of cellular events and morphological changes described above. Here, we have summarized emerging evidence and discuss new mechanistic understanding, with our perspectives, in NET formation in neutrophils.
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Affiliation(s)
- Ming-Lin Liu
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, 19104, USA,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Xing Lyu
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, 19104, USA,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA,Department of Rheumatology and Immunology, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Victoria P. Werth
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, 19104, USA,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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2
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Zheng M, Jin G, Zhou Z. Post-Translational Modification of Lamins: Mechanisms and Functions. Front Cell Dev Biol 2022; 10:864191. [PMID: 35656549 PMCID: PMC9152177 DOI: 10.3389/fcell.2022.864191] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/17/2022] [Indexed: 12/22/2022] Open
Abstract
Lamins are the ancient type V intermediate filament proteins contributing to diverse biological functions, such as the maintenance of nuclear morphology, stabilization of chromatin architecture, regulation of cell cycle progression, regulation of spatial-temporal gene expressions, and transduction of mechano-signaling. Deregulation of lamins is associated with abnormal nuclear morphology and chromatin disorganization, leading to a variety of diseases such as laminopathy and premature aging, and might also play a role in cancer. Accumulating evidence indicates that lamins are functionally regulated by post-translational modifications (PTMs) including farnesylation, phosphorylation, acetylation, SUMOylation, methylation, ubiquitination, and O-GlcNAcylation that affect protein stabilization and the association with chromatin or associated proteins. The mechanisms by which these PTMs are modified and the relevant functionality become increasingly appreciated as understanding of these changes provides new insights into the molecular mechanisms underlying the laminopathies concerned and novel strategies for the management. In this review, we discussed a range of lamin PTMs and their roles in both physiological and pathological processes, as well as potential therapeutic strategies by targeting lamin PTMs.
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Affiliation(s)
- Mingyue Zheng
- Medical Research Center, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Guoxiang Jin
- Medical Research Center, Guangdong Provincial People’s Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Zhongjun Zhou
- School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China
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3
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Liu SY, Ikegami K. Nuclear lamin phosphorylation: an emerging role in gene regulation and pathogenesis of laminopathies. Nucleus 2021; 11:299-314. [PMID: 33030403 PMCID: PMC7588210 DOI: 10.1080/19491034.2020.1832734] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Decades of studies have established that nuclear lamin polymers form the nuclear lamina, a protein meshwork that supports the nuclear envelope structure and tethers heterochromatin to the nuclear periphery. Much less is known about unpolymerized nuclear lamins in the nuclear interior, some of which are now known to undergo specific phosphorylation. A recent finding that phosphorylated lamins bind gene enhancer regions offers a new hypothesis that lamin phosphorylation may influence transcriptional regulation in the nuclear interior. In this review, we discuss the regulation, localization, and functions of phosphorylated lamins. We summarize kinases that phosphorylate lamins in a variety of biological contexts. Our discussion extends to laminopathies, a spectrum of degenerative disorders caused by lamin gene mutations, such as cardiomyopathies and progeria. We compare the prevailing hypothesis for laminopathy pathogenesis based on lamins’ function at the nuclear lamina with an emerging hypothesis based on phosphorylated lamins’ function in the nuclear interior.
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Affiliation(s)
- Sunny Yang Liu
- Department of Pediatrics, The University of Chicago , Chicago, Illinois, USA
| | - Kohta Ikegami
- Department of Pediatrics, The University of Chicago , Chicago, Illinois, USA.,Division of Molecular and Cardiovascular Biology, Cincinnati Children's Hospital Medical Center , Cincinnati, Ohio, USA
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4
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Karoutas A, Akhtar A. Functional mechanisms and abnormalities of the nuclear lamina. Nat Cell Biol 2021; 23:116-126. [PMID: 33558730 DOI: 10.1038/s41556-020-00630-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 12/22/2020] [Indexed: 01/30/2023]
Abstract
Alterations in nuclear shape are present in human diseases and ageing. A compromised nuclear lamina is molecularly interlinked to altered chromatin functions and genomic instability. Whether these alterations are a cause or a consequence of the pathological state are important questions in biology. Here, we summarize the roles of nuclear envelope components in chromatin organization, phase separation and transcriptional and epigenetic regulation. Examining these functions in healthy backgrounds will guide us towards a better understanding of pathological alterations.
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Affiliation(s)
- Adam Karoutas
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.,Francis Crick Institute, London, UK
| | - Asifa Akhtar
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.
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5
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Li Y, Li M, Weigel B, Mall M, Werth VP, Liu ML. Nuclear envelope rupture and NET formation is driven by PKCα-mediated lamin B disassembly. EMBO Rep 2020; 21:e48779. [PMID: 32537912 DOI: 10.15252/embr.201948779] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 05/22/2020] [Accepted: 05/25/2020] [Indexed: 12/23/2022] Open
Abstract
The nuclear lamina is essential for the structural integration of the nuclear envelope. Nuclear envelope rupture and chromatin externalization is a hallmark of the formation of neutrophil extracellular traps (NETs). NET release was described as a cellular lysis process; however, this notion has been questioned recently. Here, we report that during NET formation, nuclear lamin B is not fragmented by destructive proteolysis, but rather disassembled into intact full-length molecules. Furthermore, we demonstrate that nuclear translocation of PKCα, which serves as the kinase to induce lamin B phosphorylation and disassembly, results in nuclear envelope rupture. Decreasing lamin B phosphorylation by PKCα inhibition, genetic deletion, or by mutating the PKCα consensus sites on lamin B attenuates extracellular trap formation. In addition, strengthening the nuclear envelope by lamin B overexpression attenuates NET release in vivo and reduces levels of NET-associated inflammatory cytokines in UVB-irradiated skin of lamin B transgenic mice. Our findings advance the mechanistic understanding of NET formation by showing that PKCα-mediated lamin B phosphorylation drives nuclear envelope rupture for chromatin release in neutrophils.
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Affiliation(s)
- Yubin Li
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, USA.,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Minghui Li
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, USA.,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.,Department of Rheumatology and Immunology, Tianjin Medical University General Hospital, Tianjin, China
| | - Bettina Weigel
- Cell Fate Engineering and Disease Modeling Group, German Cancer Research Center (DKFZ) and DKFZ-ZMBH Alliance, Heidelberg, Germany.,HITBR Hector Institute for Translational Brain Research GmbH, Heidelberg, Germany.,Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Moritz Mall
- Cell Fate Engineering and Disease Modeling Group, German Cancer Research Center (DKFZ) and DKFZ-ZMBH Alliance, Heidelberg, Germany.,HITBR Hector Institute for Translational Brain Research GmbH, Heidelberg, Germany.,Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Victoria P Werth
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, USA.,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ming-Lin Liu
- Corporal Michael J. Crescenz VAMC, Philadelphia, PA, USA.,Department of Dermatology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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6
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Huguet F, Flynn S, Vagnarelli P. The Role of Phosphatases in Nuclear Envelope Disassembly and Reassembly and Their Relevance to Pathologies. Cells 2019; 8:cells8070687. [PMID: 31284660 PMCID: PMC6678589 DOI: 10.3390/cells8070687] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/05/2019] [Accepted: 07/06/2019] [Indexed: 12/20/2022] Open
Abstract
The role of kinases in the regulation of cell cycle transitions is very well established, however, over the past decade, studies have identified the ever-growing importance of phosphatases in these processes. It is well-known that an intact or otherwise non-deformed nuclear envelope (NE) is essential for maintaining healthy cells and any deviation from this can result in pathological conditions. This review aims at assessing the current understanding of how phosphatases contribute to the remodelling of the nuclear envelope during its disassembling and reformation after cell division and how errors in this process may lead to the development of diseases.
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Affiliation(s)
- Florentin Huguet
- College of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK
| | - Shane Flynn
- College of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK
| | - Paola Vagnarelli
- College of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, UK.
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7
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Sales Gil R, de Castro IJ, Berihun J, Vagnarelli P. Protein phosphatases at the nuclear envelope. Biochem Soc Trans 2018; 46:173-182. [PMID: 29432143 PMCID: PMC5818667 DOI: 10.1042/bst20170139] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 12/07/2017] [Accepted: 12/11/2017] [Indexed: 12/14/2022]
Abstract
The nuclear envelope (NE) is a unique topological structure formed by lipid membranes (Inner and Outer Membrane: IM and OM) interrupted by open channels (Nuclear Pore complexes). Besides its well-established structural role in providing a physical separation between the genome and the cytoplasm and regulating the exchanges between the two cellular compartments, it has become quite evident in recent years that the NE also represents a hub for localized signal transduction. Mechanical, stress, or mitogen signals reach the nucleus and trigger the activation of several pathways, many effectors of which are processed at the NE. Therefore, the concept of the NE acting just as a barrier needs to be expanded to embrace all the dynamic processes that are indeed associated with it. In this context, dynamic protein association and turnover coupled to reversible post-translational modifications of NE components can provide important clues on how this integrated cellular machinery functions as a whole. Reversible protein phosphorylation is the most used mechanism to control protein dynamics and association in cells. Keys to the reversibility of the system are protein phosphatases and the regulation of their activity in space and time. As the NE is clearly becoming an interesting compartment for the control and transduction of several signalling pathways, in this review we will focus on the role of Protein Phosphatases at the NE since the significance of this class of proteins in this context has been little explored.
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Affiliation(s)
- Raquel Sales Gil
- College of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, U.K
| | - Ines J de Castro
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg and German Center for Infection Research (DZIF), Heidelberg 69120, Germany
| | - Jerusalem Berihun
- College of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, U.K
| | - Paola Vagnarelli
- College of Health and Life Science, Research Institute for Environment Health and Society, Brunel University London, London UB8 3PH, U.K.
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8
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CDK1 and PLK1 coordinate the disassembly and reassembly of the nuclear envelope in vertebrate mitosis. Oncotarget 2017; 9:7763-7773. [PMID: 29487689 PMCID: PMC5814256 DOI: 10.18632/oncotarget.23666] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 10/31/2017] [Indexed: 12/21/2022] Open
Abstract
Micronuclei (MN) arise from chromosomes or fragments that fail to be incorporated into the primary nucleus after cell division. These structures are a major source of genetic instability caused by DNA repair and replication defects coupled to aberrant Nuclear Envelope (NE). These problems ultimately lead to a spectrum of chromosome rearrangements called chromothripsis, a phenomenon that is a hallmark of several cancers. Despite its importance, the molecular mechanism at the origin of this instability is still not understood. Here we show that lagging chromatin, although it can efficiently assemble Lamin A/C, always fails to recruit Nuclear Pore Complexes (NPCs) proteins and that Polo-Like Kinase (PLK1) negatively regulates NPC assembly. We also provide evidence for the requirement of PLK1 activity for the disassembly of NPCs, but not Lamina A/C, at mitotic entry. Altogether this study reveals the existence of independent regulatory pathways for Lamin A/C and NPC reorganization during mitosis where Lamin A/C targeting to the chromatin is controlled by CDK1 activity (a clock-based model) while the NPC loading is also spatially monitored by PLK1.
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9
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Nakai M, Ito J, Kashiwazaki N, Men N, Tanihara F, Noguchi J, Kaneko H, Onishi A, Kikuchi K. Treatment with protein kinase C activator is effective for improvement of male pronucleus formation and further embryonic development of sperm-injected oocytes in pigs. Theriogenology 2016; 85:703-8. [DOI: 10.1016/j.theriogenology.2015.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 11/26/2022]
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10
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Edens LJ, Levy DL. cPKC regulates interphase nuclear size during Xenopus development. ACTA ACUST UNITED AC 2014; 206:473-83. [PMID: 25135933 PMCID: PMC4137061 DOI: 10.1083/jcb.201406004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
During Xenopus development, increased nuclear cPKC activity and decreased nuclear association of lamins mediate nuclear scaling. Dramatic changes in cell and nuclear size occur during development and differentiation, and aberrant nuclear size is associated with many disease states. However, the mechanisms that regulate nuclear size are largely unknown. A robust system for investigating nuclear size is early Xenopus laevis development, during which reductions in nuclear size occur without changes in DNA content. To identify cellular factors that regulate nuclear size during development, we developed a novel nuclear resizing assay wherein nuclei assembled in Xenopus egg extract become smaller in the presence of cytoplasmic interphase extract isolated from post-gastrula Xenopus embryos. We show that nuclear shrinkage depends on conventional protein kinase C (cPKC). Increased nuclear cPKC localization and activity and decreased nuclear association of lamins mediate nuclear size reductions during development, and manipulating cPKC activity in vivo during interphase alters nuclear size in the embryo. We propose a model of steady-state nuclear size regulation whereby nuclear expansion is balanced by an active cPKC-dependent mechanism that reduces nuclear size.
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Affiliation(s)
- Lisa J Edens
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071
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11
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Calcium signaling and meiotic exit at fertilization in Xenopus egg. Int J Mol Sci 2014; 15:18659-76. [PMID: 25322156 PMCID: PMC4227238 DOI: 10.3390/ijms151018659] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/01/2014] [Accepted: 10/09/2014] [Indexed: 11/16/2022] Open
Abstract
Calcium is a universal messenger that mediates egg activation at fertilization in all sexually reproducing species studied. However, signaling pathways leading to calcium generation and the mechanisms of calcium-induced exit from meiotic arrest vary substantially among species. Here, we review the pathways of calcium signaling and the mechanisms of meiotic exit at fertilization in the eggs of the established developmental model, African clawed frog, Xenopus laevis. We also discuss calcium involvement in the early fertilization-induced events in Xenopus egg, such as membrane depolarization, the increase in intracellular pH, cortical granule exocytosis, cortical contraction, contraction wave, cortical rotation, reformation of the nuclear envelope, sperm chromatin decondensation and sister chromatid segregation.
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12
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Sharma M, Coen DM. Comparison of effects of inhibitors of viral and cellular protein kinases on human cytomegalovirus disruption of nuclear lamina and nuclear egress. J Virol 2014; 88:10982-5. [PMID: 24965476 PMCID: PMC4178862 DOI: 10.1128/jvi.01391-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 06/20/2014] [Indexed: 12/30/2022] Open
Abstract
Human cytomegalovirus (HCMV) kinase UL97 is required for efficient nuclear lamina disruption during nuclear egress. However, cellular protein kinase C (PKC) has been implicated in this process in other systems. Comparing the effects of UL97 and cellular kinase inhibitors on HCMV nuclear egress confirms a role for UL97 in lamina disruption and nuclear egress. A pan-PKC inhibitor did not affect lamina disruption but did reduce the number of cytoplasmic capsids more than the number of nuclear capsids.
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Affiliation(s)
- Mayuri Sharma
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Donald M Coen
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
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13
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Human cytomegalovirus UL50 and UL53 recruit viral protein kinase UL97, not protein kinase C, for disruption of nuclear lamina and nuclear egress in infected cells. J Virol 2013; 88:249-62. [PMID: 24155370 DOI: 10.1128/jvi.02358-13] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Herpesvirus nucleocapsids traverse the nuclear envelope into the cytoplasm in a process called nuclear egress that includes disruption of the nuclear lamina. In several herpesviruses, a key player in nuclear egress is a complex of two proteins, whose homologs in human cytomegalovirus (HCMV) are UL50 and UL53. However, their roles in nuclear egress during HCMV infection have not been shown. Based largely on transfection studies, UL50 and UL53 have been proposed to facilitate disruption of the nuclear lamina by recruiting cellular protein kinase C (PKC), as occurs with certain other herpesviruses, and/or the viral protein kinase UL97 to phosphorylate lamins. To investigate these issues during HCMV infection, we generated viral mutants null for UL50 or UL53. Correlative light electron microscopic analysis of null mutant-infected cells showed the presence of intranuclear nucleocapsids and the absence of cytoplasmic nucleocapsids. Confocal immunofluorescence microscopy revealed that UL50 and UL53 are required for disruption of the nuclear lamina. A subpopulation of UL97 colocalized with the nuclear rim, and this was dependent on UL50 and, to a lesser extent, UL53. However, PKC was not recruited to the nuclear rim, and its localization was not affected by the absence of UL50 or UL53. Immunoprecipitation from cells infected with HCMV expressing tagged UL53 detected UL97 but not PKC. In summary, HCMV UL50 and UL53 are required for nuclear egress and disruption of nuclear lamina during HCMV infection, and they recruit UL97, not PKC, for these processes. Thus, despite the strong conservation of herpesvirus nuclear egress complexes, a key function can differ among them.
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14
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Yamaguchi A, Iwatani M, Ogawa M, Kitano H, Matsuyama M. In vitro characterization of the RS motif in N-terminal head domain of goldfish germinal vesicle lamin B3 necessary for phosphorylation of the p34cdc2 target serine by SRPK1. FEBS Open Bio 2013; 3:165-76. [PMID: 23772390 PMCID: PMC3668540 DOI: 10.1016/j.fob.2013.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/20/2013] [Accepted: 03/21/2013] [Indexed: 11/28/2022] Open
Abstract
The nuclear envelopes surrounding the oocyte germinal vesicles of lower vertebrates (fish and frog) are supported by the lamina, which consists of the protein lamin B3 encoded by a gene found also in birds but lost in the lineage leading to mammals. Like other members of the lamin family, goldfish lamin B3 (gfLB3) contains two putative consensus phosphoacceptor p34cdc2 sites (Ser-28 and Ser-398) for the M-phase kinase to regulate lamin polymerization on the N- and C-terminal regions flanking a central rod domain. Partial phosphorylation of gfLB3 occurs on Ser-28 in the N-terminal head domain in immature oocytes prior to germinal vesicle breakdown, which suggests continual rearrangement of lamins by a novel lamin kinase in fish oocytes. We applied the expression-screening method to isolate lamin kinases by using phosphorylation site Ser-28-specific monoclonal antibody and a vector encoding substrate peptides from a goldfish ovarian cDNA library. As a result, SRPK1 was screened as a prominent lamin kinase candidate. The gfLB3 has a short stretch of the RS repeats (9-SRASTVRSSRRS-20) upstream of the Ser-28, within the N-terminal head. This stretch of repeats is conserved among fish lamin B3 but is not found in other lamins. In vitro phosphorylation studies and GST-pull down assay revealed that SRPK1 bound to the region of sequential RS repeats (9–20) with affinity and recruited serine into the active site by a grab-and-pull manner. These results indicate SRPK1 may phosphorylate the p34cdc2 site in the N-terminal head of GV-lamin B3 at the RS motifs, which have the general property of aggregation. SRPK1 was screened as a prominent lamin kinase candidate from goldfish ovary. The goldfish lamin B3 (LB3) has RS repeats upstream of the cdc2 target site. The RS repeats are conserved among fish LB3s but are not found in other lamins. SRPK1 binds to the RS repeats with affinity and phosphorylates cdc2 site by a grab-and-pull manner.
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Affiliation(s)
- Akihiko Yamaguchi
- Laboratory of Marine Biology, Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
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15
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Simon DN, Wilson KL. Partners and post-translational modifications of nuclear lamins. Chromosoma 2013; 122:13-31. [PMID: 23475188 DOI: 10.1007/s00412-013-0399-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 02/07/2013] [Accepted: 02/08/2013] [Indexed: 12/16/2022]
Abstract
Nuclear intermediate filament networks formed by A- and B-type lamins are major components of the nucleoskeleton that are required for nuclear structure and function, with many links to human physiology. Mutations in lamins cause diverse human diseases ('laminopathies'). At least 54 partners interact with human A-type lamins directly or indirectly. The less studied human lamins B1 and B2 have 23 and seven reported partners, respectively. These interactions are likely to be regulated at least in part by lamin post-translational modifications. This review summarizes the binding partners and post-translational modifications of human lamins and discusses their known or potential implications for lamin function.
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Affiliation(s)
- Dan N Simon
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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16
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Siniossoglou S. Phospholipid metabolism and nuclear function: Roles of the lipin family of phosphatidic acid phosphatases. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:575-81. [DOI: 10.1016/j.bbalip.2012.09.014] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/19/2012] [Accepted: 09/24/2012] [Indexed: 01/22/2023]
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17
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Yu JH, Liu CY, Zheng GB, Zhang LY, Yan MH, Zhang WY, Meng XY, Yu XF. Pseudolaric acid B induced cell cycle arrest, autophagy and senescence in murine fibrosarcoma l929 cell. Int J Med Sci 2013; 10:707-18. [PMID: 23630435 PMCID: PMC3638294 DOI: 10.7150/ijms.5726] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 03/28/2013] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE PAB induced various cancer cell apoptosis, cell cycle arrest and senescence. But in cell line murine fibrosarcoma L929, PAB did not induce apoptosis, but autophagy, therefore it was thought by us as a good model to research the relationship of cell cycle arrest, autophagy and senescence bypass apoptosis. METHODS Inhibitory ratio was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis. Phase contrast microscopy visualized cell morphology. Hoechst 33258 staining for nuclear change, propidium iodode (PI) staining for cell cycle, monodansylcadaverine (MDC) staining for autophagy, and rodanmine 123 staining for mitochondrial membrane potential (MMP) were measured by fluorescence microscopy or flowcytometry. Apoptosis was determined by DNA ladder test. Protein kinase C (PKC) activity was detected by PKC assay kit. SA-β-galactosidase assay was used to detect senescence. Protein expression was examined by western blot. RESULTS PAB inhibited L929 cell growth in time-and dose-dependent manner. At 12 h, 80 μmol/L PAB induced obvious mitotic arrest; at 24 h, PAB began to induce autophagy; at 36 h, cell-treated with PAB slip into G1 cell cycle; and 3 d PAB induced senescence. In time sequence PAB induced firstly cell cycle arrest, then autophagy, then slippage into G1 phase, lastly senescence. Senescent cells had high level of autophagy, inhibiting autophagy led to apoptosis, and no senescence. PAB activated PKC activity to induce cell cycle arrest, autophagy and senescence, inhibiting PKC activity suppressed cell cycle arrest, autophagy and senescence. CONCLUSION PAB induced cell cycle arrest, autophagy and senescence in murine fibrosarcoma L929 cell through PKC.
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Affiliation(s)
- Jing hua Yu
- Institute of virology and AIDS research, The first hospital of Jilin University, 519 Dongminzhu Street, Changchun 130021, P R China
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18
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Mall M, Walter T, Gorjánácz M, Davidson IF, Nga Ly-Hartig TB, Ellenberg J, Mattaj IW. Mitotic lamin disassembly is triggered by lipid-mediated signaling. J Cell Biol 2012; 198:981-90. [PMID: 22986494 PMCID: PMC3444782 DOI: 10.1083/jcb.201205103] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 08/20/2012] [Indexed: 11/22/2022] Open
Abstract
Disassembly of the nuclear lamina is a key step during open mitosis in higher eukaryotes. The activity of several kinases, including CDK1 (cyclin-dependent kinase 1) and protein kinase C (PKC), has been shown to trigger mitotic lamin disassembly, yet their precise contributions are unclear. In this study, we develop a quantitative imaging assay to study mitotic lamin B1 disassembly in living cells. We find that CDK1 and PKC act in concert to mediate phosphorylation-dependent lamin B1 disassembly during mitosis. Using ribonucleic acid interference (RNAi), we showed that diacylglycerol (DAG)-dependent PKCs triggered rate-limiting steps of lamin disassembly. RNAi-mediated depletion or chemical inhibition of lipins, enzymes that produce DAG, delayed lamin disassembly to a similar extent as does PKC inhibition/depletion. Furthermore, the delay of lamin B1 disassembly after lipin depletion could be rescued by the addition of DAG. These findings suggest that lipins activate a PKC-dependent pathway during mitotic lamin disassembly and provide evidence for a lipid-mediated mitotic signaling event.
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Affiliation(s)
- Moritz Mall
- European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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19
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Domart MC, Larijani B. Lipid-dependent and -independent regulation of nuclear envelope disassembly. J Chem Biol 2012; 6:3-5. [PMID: 24348875 DOI: 10.1007/s12154-012-0088-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 11/22/2012] [Indexed: 11/29/2022] Open
Affiliation(s)
- Marie-Charlotte Domart
- Cell Biophysics Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY UK
| | - Banafshé Larijani
- Cell Biophysics Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY UK
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20
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Kim KH, Kim EY, Kim Y, Kim E, Lee HS, Yoon SY, Lee KA. Gas6 downregulation impaired cytoplasmic maturation and pronuclear formation independent to the MPF activity. PLoS One 2011; 6:e23304. [PMID: 21850267 PMCID: PMC3151302 DOI: 10.1371/journal.pone.0023304] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2011] [Accepted: 07/14/2011] [Indexed: 11/18/2022] Open
Abstract
Previously, we found that the growth arrest-specific gene 6 (Gas6) is more highly expressed in germinal vesicle (GV) oocytes than in metaphase II (MII) oocytes using annealing control primer (ACP)-PCR technology. The current study was undertaken to investigate the role of Gas6 in oocyte maturation and fertilization using RNA interference (RNAi). Interestingly, despite the specific and marked decrease in Gas6 mRNA and protein expression in GVs after Gas6 RNAi, nuclear maturation including spindle structures and chromosome segregation was not affected. The only discernible effect induced by Gas6 RNAi was a change in maturation promoting factor (MPF) activity. After parthenogenetic activation, Gas6 RNAi-treated oocytes at the MII stage had not developed further and arrested at MII (90.0%). After stimulation with Sr(2+), Gas6-silenced MII oocytes had markedly reduced Ca(2+) oscillation and exhibited no exocytosis of cortical granules. In these oocytes, sperm penetration occurred during fertilization but not pronucleus (PN) formation. By roscovitine and colcemid treatment, we found that the Gas6 knockdown affected cytoplasmic maturation directly, independent to the changed MPF activity. These results strongly suggest that 1) the Gas6 signaling itself is important to the cytoplasmic maturation, but not nuclear maturation, and 2) the decreased Gas6 expression and decreased MPF activity separately or mutually influence sperm head decondensation and PN formation.
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Affiliation(s)
- Kyeoung-Hwa Kim
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
| | - Eun-Young Kim
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
| | - Yuna Kim
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
| | - Eunju Kim
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
| | - Hyun-Seo Lee
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
| | - Sook-Young Yoon
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
| | - Kyung-Ah Lee
- Department of Biomedical Science, College of Life Science, Fertility Center, CHA Research Institute, CHA University, CHA General Hospital, Seoul, Korea
- * E-mail:
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Abstract
The lamins are the major architectural proteins of the animal cell nucleus. Lamins line the inside of the nuclear membrane, where they provide a platform for the binding of proteins and chromatin and confer mechanical stability. They have been implicated in a wide range of nuclear functions, including higher-order genome organization, chromatin regulation, transcription, DNA replication and DNA repair. The lamins are members of the intermediate filament (IF) family of proteins, which constitute a major component of the cytoskeleton. Lamins are the only nuclear IFs and are the ancestral founders of the IF protein superfamily. Lamins polymerize into fibers forming a complex protein meshwork in vivo and, like all IF proteins, have a tripartite structure with two globular head and tail domains flanking a central α-helical rod domain, which supports the formation of higher-order polymers. Mutations in lamins cause a large number of diverse human diseases, collectively known as the laminopathies, underscoring their functional importance.
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Affiliation(s)
- Travis A Dittmer
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20896, USA.
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22
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RASCAL is a new human cytomegalovirus-encoded protein that localizes to the nuclear lamina and in cytoplasmic vesicles at late times postinfection. J Virol 2010; 84:6483-96. [PMID: 20392852 DOI: 10.1128/jvi.02462-09] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The products of numerous open reading frames (ORFs) present in the genome of human cytomegalovirus (CMV) have not been characterized. Here, we describe the identification of a new CMV protein localizing to the nuclear envelope and in cytoplasmic vesicles at late times postinfection. Based on this distinctive localization pattern, we called this new protein nuclear rim-associated cytomegaloviral protein, or RASCAL. Two RASCAL isoforms exist, a short version of 97 amino acids encoded by the majority of CMV strains and a longer version of 176 amino acids encoded by the Towne, Toledo, HAN20, and HAN38 strains. Both isoforms colocalize with lamin B in deep intranuclear invaginations of the inner nuclear membrane (INM) and in novel cytoplasmic vesicular structures possibly derived from the nuclear envelope. INM infoldings have been previously described as sites of nucleocapsid egress, which is mediated by the localized disruption of the nuclear lamina, promoted by the activities of viral and cellular kinases recruited by the lamina-associated proteins UL50 and UL53. RASCAL accumulation at the nuclear membrane required the presence of UL50 but not of UL53. RASCAL and UL50 also appeared to specifically interact, suggesting that RASCAL is a new component of the nuclear egress complex (NEC) and possibly involved in mediating nucleocapsid egress from the nucleus. Finally, the presence of RASCAL within cytoplasmic vesicles raises the intriguing possibility that this protein might participate in additional steps of virion maturation occurring after capsid release from the nucleus.
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Milbradt J, Auerochs S, Sticht H, Marschall M. Cytomegaloviral proteins that associate with the nuclear lamina: components of a postulated nuclear egress complex. J Gen Virol 2009; 90:579-590. [PMID: 19218202 DOI: 10.1099/vir.0.005231-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The nuclear egress of cytomegaloviral capsids traversing the nuclear envelope is dependent on a locally restricted destabilization of the rigid nuclear lamina. It has been suggested that the multi-component nuclear egress complex (NEC) that is formed is comprised of both viral and cellular proteins which act to recruit lamin-phosphorylating protein kinases. Recently, we reported that the lamina-associated human cytomegalovirus-encoded proteins pUL50 and pUL53, conserved among herpesviruses, interact with each other and recruit protein kinase C (PKC) to the nuclear envelope in transfected cells. The multiple interactions of the transmembrane protein pUL50 with pUL53, PKC and cellular PKC-binding protein p32, appear crucial to the formation of the NEC. In this study, we mapped individual interaction sequence elements of pUL50 by coimmunoprecipitation analysis of deletion mutants and yeast two-hybrid studies. Amino acids 1-250 were shown to be responsible for interaction with pUL53, 100-280 for PKC and 100-358 for p32. Interestingly, p32 specifically interacted with multiple NEC components, including the kinases PKC and pUL97, thus possibly acting as an adaptor for protein recruitment to the lamin B receptor. Notably, p32 was the only protein that interacted with the lamin B receptor. Immunofluorescence studies visualized the colocalization of NEC components at the nuclear rim in coexpression studies. The data imply that a tight interaction between at least six viral and cellular proteins leads to the formation of a postulated multi-protein complex required for nuclear egress.
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Affiliation(s)
- Jens Milbradt
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
| | - Sabrina Auerochs
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
| | - Heinrich Sticht
- Division of Bioinformatics, Institute of Biochemistry, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
| | - Manfred Marschall
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
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Herpesvirus gB-induced fusion between the virion envelope and outer nuclear membrane during virus egress is regulated by the viral US3 kinase. J Virol 2009; 83:3115-26. [PMID: 19158241 DOI: 10.1128/jvi.01462-08] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Herpesvirus capsids collect along the inner surface of the nuclear envelope and bud into the perinuclear space. Enveloped virions then fuse with the outer nuclear membrane (NM). We previously showed that herpes simplex virus (HSV) glycoproteins gB and gH act in a redundant fashion to promote fusion between the virion envelope and the outer NM. HSV mutants lacking both gB and gH accumulate enveloped virions in herniations, vesicles that bulge into the nucleoplasm. Earlier studies had shown that HSV mutants lacking the viral serine/threonine kinase US3 also accumulate herniations. Here, we demonstrate that HSV gB is phosphorylated in a US3-dependent manner in HSV-infected cells, especially in a crude nuclear fraction. Moreover, US3 directly phosphorylated the gB cytoplasmic (CT) domain in in vitro assays. Deletion of gB in the context of a US3-null virus did not add substantially to defects in nuclear egress. The majority of the US3-dependent phosphorylation of gB involved the CT domain and amino acid T887, a residue present in a motif similar to that recognized by US3 in other proteins. HSV recombinants lacking gH and expressing either gB substitution mutation T887A or a gB truncated at residue 886 displayed substantial defects in nuclear egress. We concluded that phosphorylation of the gB CT domain is important for gB-mediated fusion with the outer NM. This suggested a model in which the US3 kinase is incorporated into the tegument layer (between the capsid and envelope) in HSV virions present in the perinuclear space. By this packaging, US3 might be brought close to the gB CT tail, leading to phosphorylation and triggering fusion between the virion envelope and the outer NM.
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25
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Swain JE, Pool TB. ART failure: oocyte contributions to unsuccessful fertilization. Hum Reprod Update 2008; 14:431-46. [DOI: 10.1093/humupd/dmn025] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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26
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Ducibella T, Fissore R. The roles of Ca2+, downstream protein kinases, and oscillatory signaling in regulating fertilization and the activation of development. Dev Biol 2008; 315:257-79. [PMID: 18255053 DOI: 10.1016/j.ydbio.2007.12.012] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 12/12/2007] [Accepted: 12/13/2007] [Indexed: 12/12/2022]
Abstract
Reviews in Developmental Biology have covered the pathways that generate the all-important intracellular calcium (Ca(2+)) signal at fertilization [Miyazaki, S., Shirakawa, H., Nakada, K., Honda, Y., 1993a. Essential role of the inositol 1,4,5-trisphosphate receptor/Ca(2+) release channel in Ca(2+) waves and Ca(2+) oscillations at fertilization of mammalian eggs. Dev. Biol. 158, 62-78; Runft, L., Jaffe, L., Mehlmann, L., 2002. Egg activation at fertilization: where it all begins. Dev. Biol. 245, 237-254] and the different temporal responses of Ca(2+) in many organisms [Stricker, S., 1999. Comparative biology of calcium signaling during fertilization and egg activation in animals. Dev. Biol. 211, 157-176]. Those reviews raise the importance of identifying how Ca(2+) causes the events of egg activation (EEA) and to what extent these temporal Ca(2+) responses encode developmental information. This review covers recent studies that have analyzed how these Ca(2+) signals are interpreted by specific proteins, and how these proteins regulate various EEA responsible for the onset of development. Many of these proteins are protein kinases (CaMKII, PKC, MPF, MAPK, MLCK) whose activity is directly or indirectly regulated by Ca(2+), and whose amount increases during late oocyte maturation. We cover biochemical progress in defining the signaling pathways between Ca(2+) and the EEA, as well as discuss how oscillatory or multiple Ca(2+) signals are likely to have specific advantages biochemically and/or developmentally. These emerging concepts are put into historical context, emphasizing that key contributions have come from many organisms. The intricate interdependence of Ca(2+), Ca(2+)-dependent proteins, and the EEA raise many new questions for future investigations that will provide insight into the extent to which fertilization-associated signaling has long-range implications for development. In addition, answers to these questions should be beneficial to establishing parameters of egg quality for human and animal IVF, as well as improving egg activation protocols for somatic cell nuclear transfer to generate stem cells and save endangered species.
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Affiliation(s)
- Tom Ducibella
- Department of OB/GYN, Tufts-New England Medical Center, Boston, MA 02111, USA.
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27
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Milbradt J, Auerochs S, Marschall M. Cytomegaloviral proteins pUL50 and pUL53 are associated with the nuclear lamina and interact with cellular protein kinase C. J Gen Virol 2007; 88:2642-2650. [PMID: 17872514 DOI: 10.1099/vir.0.82924-0] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human cytomegalovirus-encoded pUL50 and pUL53 belong to a group of conserved herpesviral nuclear proteins. This study describes: (i) the co-localization of pUL50 with components of the nuclear lamina such as lamins A/C and lamin B receptor by double immunofluorescent staining, (ii) a strong pUL50-mediated relocalization of pUL53 from a diffuse nuclear pattern towards a nuclear rim localization, (iii) a direct interaction between pUL50 and pUL53, as well as between pUL50 and protein kinase C (PKC), shown by yeast two-hybrid and co-immunoprecipitation analyses, (iv) in vitro phosphorylation of pUL50, which is highly suggestive of PKC activity, and finally (v) partial relocalization of PKC by pUL50/pUL53 from its main cytoplasmic localization to a marked nuclear lamina accumulation. These data suggest a role for pUL50 and pUL53 in the recruitment of PKC, an event that is considered to be important for cytomegalovirus-induced distortion of the nuclear lamina.
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Affiliation(s)
- Jens Milbradt
- Virological Institute of the University Hospital Erlangen, Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
| | - Sabrina Auerochs
- Virological Institute of the University Hospital Erlangen, Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
| | - Manfred Marschall
- Virological Institute of the University Hospital Erlangen, Clinical and Molecular Virology, University of Erlangen-Nuremberg, 91054 Erlangen, Germany
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28
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Mou F, Forest T, Baines JD. US3 of herpes simplex virus type 1 encodes a promiscuous protein kinase that phosphorylates and alters localization of lamin A/C in infected cells. J Virol 2007; 81:6459-70. [PMID: 17428859 PMCID: PMC1900093 DOI: 10.1128/jvi.00380-07] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The herpes simplex virus type 1 (HSV-1) US3 gene encodes a serine/threonine kinase that, when inactivated, causes capsids to aggregate aberrantly between the inner and outer nuclear membranes (INM and ONM, respectively) within evaginations/extensions of the perinuclear space. In both Hep2 cells and an engineered cell line derived from Hep2 cells expressing lamin A/C fused to enhanced green fluorescent protein (eGFP-lamin A/C), lamin A/C localized mostly in a reticular pattern with small regions of the INM devoid of eGFP-lamin A/C when they were either mock infected or infected with wild-type HSV-1(F). Cells infected with HSV-1(F) also contained some larger diffuse regions lacking lamin A/C. Proteins UL31 and UL34, markers of potential envelopment sites at the INM and perinuclear virions, localized within the regions devoid of lamin A/C and also in regions containing lamin A/C. Similar to previous observations with Vero cells (S. L. Bjerke and R. J. Roller, Virology 347:261-276, 2006), the proteins UL34 and UL31 localized exclusively in very discrete regions of the nuclear lamina lacking lamin A/C in the absence of US3 kinase activity. To determine how US3 alters lamin A/C distribution, US3 was purified and shown to phosphorylate lamin A/C at multiple sites in vitro, despite the presence of only one putative US3 kinase consensus site in the lamin A/C sequence. US3 kinase activity was also sufficient to invoke partial solubilization of lamin A/C from permeabilized Hep2 cell nuclei in an ATP-dependent manner. Two-dimensional electrophoretic analyses of lamin A/C revealed that lamin A/C is phosphorylated in HSV-infected cells, and the full spectrum of phosphorylation requires US3 kinase activity. These data suggest that US3 kinase activity regulates HSV-1 capsid nuclear egress at least in part by phosphorylation of lamin A/C.
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Affiliation(s)
- Fan Mou
- Department of Microbiology and Immunology, C5143 Veterinary Education Center, Cornell University, Ithaca, NY 14853, USA
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29
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Larijani B, Poccia D. Protein and lipid signaling in membrane fusion: nuclear envelope assembly. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/sita.200600128] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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30
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Broers JLV, Ramaekers FCS, Bonne G, Yaou RB, Hutchison CJ. Nuclear Lamins: Laminopathies and Their Role in Premature Ageing. Physiol Rev 2006; 86:967-1008. [PMID: 16816143 DOI: 10.1152/physrev.00047.2005] [Citation(s) in RCA: 441] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
It has been demonstrated that nuclear lamins are important proteins in maintaining cellular as well as nuclear integrity, and in maintaining chromatin organization in the nucleus. Moreover, there is growing evidence that lamins play a prominent role in transcriptional control. The family of laminopathies is a fast-growing group of diseases caused by abnormalities in the structure or processing of the lamin A/C ( LMNA) gene. Mutations or incorrect processing cause more than a dozen different inherited diseases, ranging from striated muscular diseases, via fat- and peripheral nerve cell diseases, to progeria. This broad spectrum of diseases can only be explained if the responsible A-type lamin proteins perform multiple functions in normal cells. This review gives an overview of current knowledge on lamin structure and function and all known diseases associated with LMNA abnormalities. Based on the knowledge of the different functions of A-type lamins and associated proteins, explanations for the observed phenotypes are postulated. It is concluded that lamins seem to be key players in, among others, controlling the process of cellular ageing, since disturbance in lamin protein structure gives rise to several forms of premature ageing.
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Affiliation(s)
- J L V Broers
- Department of Molecular Cell Biology, University of Maastricht, Research Institutes CARIM, GROW, and EURON, The Netherlands
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31
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Yamaguchi A, Katsu Y, Matsuyama M, Yoshikuni M, Nagahama Y. Phosphorylation of the p34(cdc2) target site on goldfish germinal vesicle lamin B3 before oocyte maturation. Eur J Cell Biol 2006; 85:501-17. [PMID: 16600424 DOI: 10.1016/j.ejcb.2006.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2005] [Revised: 02/07/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022] Open
Abstract
The nuclear membranes surrounding fish and frog oocyte germinal vesicles (GVs) are supported by the lamina, an internal, mesh-like structure that consists of the protein lamin B3. The mechanisms by which lamin B3 is transported into GVs and is assembled to form the nuclear lamina are not well understood. In this study, we developed a heterogeneous microinjection system in which wild-type or mutated goldfish GV lamin B3 (GFLB3) was expressed in Escherichia coli, biotinylated, and microinjected into Xenopus oocytes. The localization of the biotinylated GFLB3 was visualized by fluorescence confocal microscopy. The results of these experiments indicated that the N-terminal domain plays important roles in both nuclear transport and assembly of lamin B3 to form the nuclear lamina. The N-terminal domain includes a major consensus phosphoacceptor site for the p34(cdc2) kinase at amino acid residue Ser-28. To investigate nuclear lamin phosphorylation, we generated a monoclonal antibody (C7B8D) against Ser-28-phosphorylated GFLB3. Two-dimensional (2-D) electrophoresis of GV protein revealed two major spots of lamin B3 with different isoelectric points (5.9 and 6.1). The C7B8D antibody recognized the pI-5.9 spot but not the pI-6.1 spot. The former spot disappeared when the native lamina was incubated with lambda phage protein phosphatase (lambda-PP), indicating that a portion of the lamin protein was already phosphorylated in the goldfish GV-stage oocytes. GFLB3 that had been microinjected into Xenopus oocytes was also phosphorylated in Xenopus GV lamina, as judged by Western blotting with C7B8D. Thus, lamin phosphorylation appears to occur prior to oocyte maturation in vivo in both these species. Taken together, our results suggest that the balance between phosphorylation by interphase lamin kinases and dephosphorylation by phosphatases regulates the conformational changes in the lamin B3 N-terminal head domain that in turn regulates the continual in vivo rearrangement and remodeling of the oocyte lamina.
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Affiliation(s)
- Akihiko Yamaguchi
- Laboratory of Marine Biology, Department of Animal and Marine Bioresource Sciences, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-Ku, Fukuoka 812-8581, Japan.
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32
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Nichols RJ, Wiebe MS, Traktman P. The vaccinia-related kinases phosphorylate the N' terminus of BAF, regulating its interaction with DNA and its retention in the nucleus. Mol Biol Cell 2006; 17:2451-64. [PMID: 16495336 PMCID: PMC1446082 DOI: 10.1091/mbc.e05-12-1179] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The vaccinia-related kinases (VRKs) comprise a branch of the casein kinase family whose members are characterized by homology to the vaccinia virus B1 kinase. The VRK orthologues encoded by Caenorhabditis elegans and Drosophila melanogaster play an essential role in cell division; however, substrates that mediate this role have yet to be elucidated. VRK1 can complement the temperature sensitivity of a vaccinia B1 mutant, implying that VRK1 and B1 have overlapping substrate specificity. Herein, we demonstrate that B1, VRK1, and VRK2 efficiently phosphorylate the extreme N' terminus of the BAF protein (Barrier to Autointegration Factor). BAF binds to both DNA and LEM domain-containing proteins of the inner nuclear membrane; in lower eukaryotes, BAF has been shown to play an important role during the reassembly of the nuclear envelope at the end of mitosis. We demonstrate that phosphorylation of ser4 and/or thr2/thr3 abrogates the interaction of BAF with DNA and reduces its interaction with the LEM domain. Coexpression of VRK1 and GFP-BAF greatly diminishes the association of BAF with the nuclear chromatin/matrix and leads to its dispersal throughout the cell. Cumulatively, our data suggest that the VRKs may modulate the association of BAF with nuclear components and hence play a role in maintaining appropriate nuclear architecture.
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Affiliation(s)
- R Jeremy Nichols
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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33
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Marschall M, Marzi A, aus dem Siepen P, Jochmann R, Kalmer M, Auerochs S, Lischka P, Leis M, Stamminger T. Cellular p32 recruits cytomegalovirus kinase pUL97 to redistribute the nuclear lamina. J Biol Chem 2005; 280:33357-67. [PMID: 15975922 DOI: 10.1074/jbc.m502672200] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Replication of human cytomegalovirus is limited at the level of nucleocytoplasmic transport of viral capsids, a process that requires the disassembly of the nuclear lamina. Deletion of the protein kinase gene UL97 from the viral genome showed that the activity of pUL97 plays an important role for viral capsid egress. Here, we report that p32, a novel cellular interactor of the viral kinase pUL97, promotes the accumulation of pUL97 at the nuclear membrane by recruiting the p32-pUL97 complex to the lamin B receptor. Transfection of active pUL97, but not a catalytically inactive mutant, induced a redistribution of lamina components as demonstrated for recombinant lamin B receptor-green fluorescent protein and endogenous lamins A and C. Consistent with this, p32 itself and lamins were phosphorylated by pUL97. Importantly, overexpression of p32 in human cytomegalovirus-infected cells resulted in increased efficiency of viral replication and release of viral particles. Thus, it is highly suggestive that the cellular protein p32 recruits pUL97 to induce a dissolution of the nuclear lamina thereby facilitating the nuclear export of viral capsids.
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Affiliation(s)
- Manfred Marschall
- Institute for Clinical and Molecular Virology, University of Erlangen-Nürnberg, Erlangen 91054, Germany.
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34
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Zheng ZY, Li QZ, Chen DY, Schatten H, Sun QY. Translocation of phospho-protein kinase Cs implies their roles in meiotic-spindle organization, polar-body emission and nuclear activity in mouse eggs. Reproduction 2005; 129:229-34. [PMID: 15695617 DOI: 10.1530/rep.1.00336] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The protein kinase Cs (PKCs) are a family of Ser/Thr protein kinases categorized into three subfamilies: classical, novel, and atypical. The phosphorylation of PKC in germ cells is not well defined. In this study, we described the subcellular localization of phopho-PKC in the process of mouse oocyte maturation, fertilization, and early embryonic mitosis. Confocal microscopy revealed that phospho-PKC (pan) was distributed abundantly in the nucleus at the germinal vesicle stage. After germinal vesicle breakdown, phospho-PKC was localized in the vicinity of the condensed chromosomes, distributed in the whole meiotic spindle, and concentrated at the spindle poles. After metaphase I, phospho-PKC was translocated gradually to the spindle mid-zone during emission of the first polar body. After sperm penetration and electrical activation, the distribution of phospho-PKC was moved from the spindle poles to the spindle mid-zone. After the extrusion of the second polar body (PB2) phospho-PKC was localized in the area between the oocyte and the PB2. In fertilized eggs, phospho-PKC was concentrated in the pronuclei except for the nucleolus. Phospho-PKC was dispersed after pronuclear envelope breakdown, but distributed on the entire spindle at mitotic metaphase. The results suggest that PKC activation may play important roles in regulating spindle organization and stabilization, polar-body extrusion, and nuclear activity during mouse oocyte meiosis, fertilization, and early embryonic mitosis.
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Affiliation(s)
- Zhen-Yu Zheng
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People's Republic of China
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35
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Veluthakal R, Amin R, Kowluru A. Interleukin-1β induces posttranslational carboxymethylation and alterations in subnuclear distribution of lamin B in insulin-secreting RINm5F cells. Am J Physiol Cell Physiol 2004; 287:C1152-62. [PMID: 15201138 DOI: 10.1152/ajpcell.00083.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We examined the effects of interleukin-1β (IL-1β) treatment on the distribution and degradation of lamin B in the nuclear fraction from insulin-secreting RINm5F cells. Western blot analysis indicated that IL-1β treatment caused significant alterations in the redistribution of lamin B, specifically between the Triton X-100-soluble (membrane) and -insoluble (matrix) fractions of the nucleus. IL-1β treatment also increased the lamin carboxymethyltransferase activity and the relative abundance of the carboxymethylated lamin in the nuclear fraction. A significant increase in the relative abundance of lamin B degradation products was also observed in the nuclear fraction from the IL-1β-treated cells. These findings are compatible with a measurable increase in the lamin-degrading caspase-6 activity in IL-1β-treated cells. Confocal microscopic observation of IL-1β-treated cells suggested a significant dissociation of lamin B from the nuclear lamina and its subsequent association with the DNA-rich elements within the nucleus. NG-monomethyl-l-arginine, a known inhibitor of inducible nitric oxide synthetase (iNOS), markedly inhibited IL-1β-induced iNOS gene expression, NO release, caspase-3 and caspase-6 activation, lamin B degradation, and loss of metabolic cell viability, indicating that the observed IL-1β-induced effects on nuclear lamin B involve the intermediacy of NO. Together, our data support the hypothesis that IL-1β treatment results in significant increase in the carboxymethylation of lamin B, which would place lamin B in a strategic location for its degradation mediated by caspases. This could possibly lead to dissolution of the nuclear envelope, culminating in the demise of the effete β-cell.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Ave., Detroit, MI 48201, USA
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36
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Gruenbaum Y, Goldman RD, Meyuhas R, Mills E, Margalit A, Fridkin A, Dayani Y, Prokocimer M, Enosh A. The nuclear lamina and its functions in the nucleus. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 226:1-62. [PMID: 12921235 DOI: 10.1016/s0074-7696(03)01001-5] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The nuclear lamina is a structure near the inner nuclear membrane and the peripheral chromatin. It is composed of lamins, which are also present in the nuclear interior, and lamin-associated proteins. The increasing number of proteins that interact with lamins and the compound interactions between these proteins and chromatin-associated proteins make the nuclear lamina a highly complex but also a very exciting structure. The nuclear lamina is an essential component of metazoan cells. It is involved in most nuclear activities including DNA replication, RNA transcription, nuclear and chromatin organization, cell cycle regulation, cell development and differentiation, nuclear migration, and apoptosis. Specific mutations in nuclear lamina genes cause a wide range of heritable human diseases. These diseases include Emery-Dreifuss muscular dystrophy, limb girdle muscular dystrophy, dilated cardiomyopathy (DCM) with conduction system disease, familial partial lipodystrophy (FPLD), autosomal recessive axonal neuropathy (Charcot-Marie-Tooth disorder type 2, CMT2), mandibuloacral dysplasia (MAD), Hutchison Gilford Progeria syndrome (HGS), Greenberg Skeletal Dysplasia, and Pelger-Huet anomaly (PHA). Genetic analyses in Caenorhabditis elegans, Drosophila, and mice show new insights into the functions of the nuclear lamina, and recent structural analyses have begun to unravel the molecular structure and assembly of lamins and their associated proteins.
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Affiliation(s)
- Yosef Gruenbaum
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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37
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Stephens S, Beyer B, Balthazar-Stablein U, Duncan R, Kostacos M, Lukoma M, Green GR, Poccia D. Two kinase activities are sufficient for sea urchin sperm chromatin decondensation in vitro. Mol Reprod Dev 2002; 62:496-503. [PMID: 12112583 DOI: 10.1002/mrd.90005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Decondensation of compact and inactive sperm chromatin by egg cytoplasm at fertilization is necessary to convert the male germ cell chromatin to an active somatic form. We studied decondensation of sea urchin sperm nuclei in a cell-free extract of sea urchin eggs to define conditions promoting decondensation. We find that egg cytosol specifically phosphorylates two sperm-specific (Sp) histones in vitro in the same regions as in vivo. This activity is blocked by olomoucine, an inhibitor of cdc2-like kinases, but not by chelerythrine, an inhibitor of protein kinase C (PKC). PKC phosphorylates and solubilizes the sperm nuclear lamina, one requirement for decondensation. Olomoucine, which does not inhibit lamina removal, blocks sperm nuclear decondensation in the same concentration range over which it is effective in blocking Sp histone phosphorylation. In a system free of other soluble proteins, neither PKC nor cdc2 alone elicit sperm chromatin decondensation, but the two act synergistically to decondense sperm nuclei. We conclude that two kinases activities are sufficient for sea urchin male pronuclear decondensation in vitro, a lamin kinase (PKC) and a cdc2-like Sp histone kinase.
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Affiliation(s)
- S Stephens
- Department of Biology, Amherst College, Amherst, Massachusetts 01002, USA
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38
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La Porta CAM, Porro D, Comolli R. Higher levels of melanin and inhibition of cdk2 activity in primary human melanoma cells WM115 overexpressing nPKCdelta. Melanoma Res 2002; 12:297-307. [PMID: 12170178 DOI: 10.1097/00008390-200208000-00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Many studies have attempted to define the state of differentiation of melanoma cells and to correlate it with other critical parameters of malignancy such as the tumorigenic and metastatic nature of the cells. In the present paper we focused on the possible relationships between the novel protein kinase C isoform nPKCdelta, melanin synthesis and proliferative capacity in a primary human melanoma cell line WM115. Cells were transfected to produce overexpression of this isoform and the effects on melanin synthesis, cyclin-E dependent kinase (cdk2) activity and cyclin E expression were studied. It was shown that translocation of nPKCdelta into the nucleus affects melanin synthesis and inhibits cdk2 activity. As a compensatory effect, the level of cyclin E increases. In view of these results we suggest a model for the role of nPKCdelta in melanoma cells that may offer a new therapeutic perspective.
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Affiliation(s)
- Caterina A M La Porta
- Department of General Physiology and Biochemistry, Section of General Pathology, University of Milan, Celoria 26, 20133 Milan, Italy.
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39
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Dantzer F, Luna L, Bjørås M, Seeberg E. Human OGG1 undergoes serine phosphorylation and associates with the nuclear matrix and mitotic chromatin in vivo. Nucleic Acids Res 2002; 30:2349-57. [PMID: 12034821 PMCID: PMC117190 DOI: 10.1093/nar/30.11.2349] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OGG1 is the major DNA glycosylase in human cells for removal of 7,8 dihydro-8-oxoguanine (8-oxoG), one of the most frequent endogenous base lesions formed in the DNA of aerobic organisms. During replication, 8-oxoG will frequently mispair with adenine, thus forming G:C --> T:A transversions, a common somatic mutation associated with human cancers. In the present study, we have constructed a stable transfectant cell line expressing hOGG1 fused at the C-terminal end to green fluorescent protein (GFP) and investigated the cellular distribution of the fusion protein by fluorescence analysis. It is shown that hOGG1 is preferentially associated with chromatin and the nuclear matrix during interphase and becomes associated with the condensed chromatin during mitosis. Chromatin-bound hOGG1 was found to be phosphorylated on a serine residue in vivo as revealed by staining with an anti-phosphoserine-specific antibody. Chromatin-associated hOGG1 was co-precipitated with an antibody against protein kinase C (PKC), suggesting that PKC is responsible for the phosphorylation event. Both purified and nuclear matrix-associated hOGG1 were shown to be substrates for PKC-mediated phosphorylation in vitro. This appears to be the first demonstration of a post-translational modification of hOGG1 in vivo.
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Affiliation(s)
- Françoise Dantzer
- Department of Molecular Biology, Institute of Medical Microbiology, University of Oslo, Rikshospitalet, Sognsvannveien 20, NO-0027 Oslo, Norway
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40
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Chiarini A, Whitfield JF, Armato U, Dal Pra I. Protein kinase C-beta II Is an apoptotic lamin kinase in polyomavirus-transformed, etoposide-treated pyF111 rat fibroblasts. J Biol Chem 2002; 277:18827-39. [PMID: 11901153 DOI: 10.1074/jbc.m111921200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of protein kinase C-beta(II) (PKC-beta(II)) in etoposide (VP-16)-induced apoptosis was studied using polyomavirus-transformed pyF111 rat fibroblasts in which PKC-beta(II) specific activity in the nuclear membrane (NM) doubled and the enzyme was cleaved into catalytic fragments. No PKC-beta(II) complexes with lamin B1 and/or active caspases were immunoprecipitable from the NM of proliferating untreated cells, but large complexes of PKC-beta(II) holoprotein and its catalytic fragments with lamin B1, active caspase-3 and -6, and inactive phospho-CDK-1, but not PKC-beta(I) or PKC-delta, could be immunoprecipitated from the NM of VP-16-treated cells, suggesting that PKC-beta(II) is an apoptotic lamin kinase. By 30 min after normal nuclei were mixed with cytoplasms from VP-16-treated, but not untreated, cells, PKC-beta(II) holoprotein had moved from the apoptotic cytoplasm to the normal NM, and lamin B1 was phosphorylated before cleavage by caspase-6. Lamin B1 phosphorylation was partly reduced, but its cleavage was completely prevented, despite the presence of active caspase-6, by adding a selective PKC-betas inhibitor, hispidin, to the apoptotic cytoplasms. Thus, a PKC-beta(II) response to VP-16 seems necessary for lamin B1 cleavage by caspase-6 and nuclear lamina dissolution in apoptosing pyF111 fibroblasts. The possibility of PKC-beta(II) being an apoptotic lamin kinase in these cells was further suggested by lamin B1-bound PKC-delta being inactive or only slightly active and by PKC-alpha not combining with the lamin.
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Affiliation(s)
- Anna Chiarini
- Histology and Embryology Unit, Department of Biomedical and Surgical Sciences, Medical School, University of Verona, Verona I-37134, Italy
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41
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Otto H, Dreger M, Bengtsson L, Hucho F. Identification of tyrosine-phosphorylated proteins associated with the nuclear envelope. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:420-8. [PMID: 11168378 DOI: 10.1046/j.1432-1033.2001.01901.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The nuclear envelope separates the nucleoplasm from the rest of the cell. Throughout the cell cycle, its structural integrity is controlled by reversible protein phosphorylation. Whereas its phosphorylation-dependent disassembly during mitosis is well characterized, little is known about phosphorylation events at this structure during interphase. The few characterized examples cover protein phosphorylation at serine and threonine residues, but not tyrosine phosphorylation at the nuclear envelope. Here, we demonstrate that tyrosine phosphorylation and dephosphorylation occur at the nuclear envelope of intact Neuro2a mouse neuroblastoma cells. Tyrosine kinase and phosphatase activities remain associated with purified nuclear envelopes. A similar pattern of tyrosine-phosphorylated nuclear envelope proteins suggests that the same tyrosine kinases act at the nuclear envelope of intact cells and at the purified nuclear envelope. We have also identified eight tyrosine-phosphorylated nuclear envelope proteins by 2D BAC/SDS/PAGE, immunoblotting with phosphotyrosine-specific antibodies, tryptic in-gel digestion, and MS analysis of tryptic peptides. These proteins are the lamina proteins lamin A, lamin B1, and lamin B2, the inner nuclear membrane protein LAP2beta, the heat shock protein hsc70, and the DNA/RNA-binding proteins PSF, hypothetical 16-kDa protein, and NonO, which copurify with the nuclear envelope.
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Affiliation(s)
- H Otto
- Freie Universität Berlin, Institut für Chemie-Biochemie, Berlin, Germany
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42
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Abstract
At fertilization, the dormant sperm nucleus undergoes morphological and biochemical transformations leading to the development of a functional male pronucleus. We have investigated the formation of the male pronucleus in a cell-free system consisting of permeabilized sea urchin sperm nuclei incubated in fertilized sea urchin egg extract containing membrane vesicles. The first sperm nuclear transformation observed in vitro is the disassembly of the sperm nuclear lamina as a result of lamin B phosphorylation mediated by egg protein kinase C. The conical sperm nucleus then decondenses into a spherical pronucleus in an ATP-dependent manner. The new nuclear envelope (NE) forms by ATP-dependent binding of vesicles to chromatin and GTP-dependent fusion of vesicles with one another. Three cytoplasmic vesicle fractions with distinct properties are required for the formation of the male pronuclear envelope. Binding of each fraction to chromatin requires two detergent-resistant lipophilic structures at each pole of the sperm nucleus, which are incorporated into the NE by membrane fusion. Targeting of the bulk of NE vesicles to chromatin is mediated by a lamin B receptor (LBR)-like integral membrane protein. The last step of male pronuclear formation involves nuclear swelling. Nuclear swelling is associated with import of soluble lamin B into the nucleus and growth of the NE. In the nucleus, lamin B associates with LBR, which apparently tethers the NE to the lamina. Thus, formation of the male pronuclear envelope involves a highly ordered series of reactions.
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Affiliation(s)
- P Collas
- Institute of Medical Biochemistry, Faculty of Medicine, University of Oslo, Norway.
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43
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Morin V, Acuña P, Díaz F, Inostroza D, Martinez J, Montecino M, Puchi M, Imschenetzky M. Phosphorylation protects sperm-specific histones H1 and H2B from proteolysis after fertilization. J Cell Biochem 1999; 76:173-80. [PMID: 10618634 DOI: 10.1002/(sici)1097-4644(20000201)76:2<173::aid-jcb1>3.0.co;2-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
At intermediate stages of male pronucleus formation, sperm-derived chromatin is composed of hybrid nucleoprotein particles formed by sperm H1 (SpH1), dimers of sperm H2A-H2B (SpH2A-SpH2B), and a subset of maternal cleavage stage (CS) histone variants. At this stage in vivo, the CS histone variants are poly(ADP-ribosylated), while SpH2B and SpH1 are phosphorylated. We have postulated previously that the final steps of sperm chromatin remodeling involve a cysteine-protease (SpH-protease) that degrades sperm histones in a specific manner, leaving the maternal CS histone variants unaffected. More recently we have reported that the protection of CS histones from degradation is determined by the poly(ADP-ribose) moiety of these proteins. Because of the selectivity displayed by the SpH-protease, the coexistence of a subset of SpH together with CS histone variants at intermediate stages of male pronucleus remodeling remains intriguing. Consequently, we have investigated the phosphorylation state of SpH1 and SpH2B in relation to the possible protection of these proteins from proteolytic degradation. Histones H1 and H2B were purified from sperm, phosphorylated in vitro using the recombinant alpha-subunit of casein kinase 2, and then used as substrates in the standard assay of the SpH-protease. The phosphorylated forms of SpH1 and SpH2B were found to remain unaltered, while the nonphosphorylated forms were degraded. On the basis of this result, we postulate a novel role for the phosphorylation of SpH1 and SpH2B that occurs in vivo after fertilization, namely to protect these histones against degradation at intermediate stages of male chromatin remodeling.
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Affiliation(s)
- V Morin
- Department of Molecular Biology, Universidad de Concepci¿on, Casilla 160-C, Concepci¿on, Chile
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44
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Latham KE. Mechanisms and control of embryonic genome activation in mammalian embryos. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 193:71-124. [PMID: 10494621 DOI: 10.1016/s0074-7696(08)61779-9] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Activation of transcription within the embryonic genome (EGA) after fertilization is a complex process requiring a carefully coordinated series of nuclear and cytoplasmic events, which collectively ensure that the two parental genomes can be faithfully reprogrammed and restructured before transcription occurs. Available data indicate that inappropriate transcription of some genes during the period of nuclear reprogramming can have long-term detrimental effects on the embryo. Therefore, precise control over the time of EGA is essential for normal embryogenesis. In most mammals, genome activation occurs in a stepwise manner. In the mouse, for example, some transcription occurs during the second half of the one-cell stage, and then a much greater phase of genome activation occurs in two waves during the two-cell stage, with the second wave producing the largest onset of de novo gene expression. Changes in nuclear structure, chromatin structure, and cytoplasmic macromolecular content appear to regulate these periods of transcriptional activation. A model is presented in which a combination of cell cycle-dependent events and both translational and posttranslational regulatory mechanisms within the cytoplasm play key roles in mediating and regulating EGA.
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Affiliation(s)
- K E Latham
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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45
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46
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Abstract
The delivery of the paternal genome to the egg is a primary goal of fertilization. In preparation for this step, the nucleus of the developing spermatozoon undergoes extensive morphological and biochemical transformations during spermatogenesis to yield a tightly compacted sperm nucleus. These modifications are essentially reversed during fertilization. As a result, the incorporated sperm nucleus undergoes many steps in the egg cytoplasm as it develops into a male pronucleus. The sperm nucleus (1) loses its nuclear envelope, (2) undergoes nucleoprotein remodeling, (3) decondenses and increases in size, (4) becomes more spherical, (5) acquires a new nuclear envelope, and (6) becomes functionally competent to synthesize DNA and RNA. These changes are coordinate with meiotic processing of the maternal chromatin, and often result in behaviors asynchronous with the maternal chromatin. For example, in eggs fertilized during meiosis, the sperm nucleus decondenses while the maternal chromatin remains condensed. A model is presented that suggests some reasons why this puzzling behavior exists. Defects in any of the processes attending male pronuclear development often result in infertility. New assisted reproductive technologies have been developed that ensure delivery of the sperm nucleus to the egg cytoplasm so that a healthy embryo is produced. An emerging challenge is to further characterize the molecular mechanisms that control sperm nuclear transformations and link these to causes of human infertility. Further understanding of this basic process promises to revolutionize our understanding of the mystery of the beginning of new life.
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Affiliation(s)
- S J Wright
- Department of Biology, University of Dayton, Ohio 45469, USA
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47
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Dreger M, Otto H, Neubauer G, Mann M, Hucho F. Identification of phosphorylation sites in native lamina-associated polypeptide 2 beta. Biochemistry 1999; 38:9426-34. [PMID: 10413518 DOI: 10.1021/bi990645f] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lamina-associated polypeptide 2 beta (LAP 2 beta), an integral protein of the inner nuclear membrane, appears to be involved in the spatial organization of the interface between nucleoplasma, lamina, and nuclear envelope. Its ability to interact with other proteins and the structural integrity of the nuclear envelope is probably regulated by phosphorylation. Here, we report nonmitotic LAP 2 beta phosphorylation sites that are phosphorylated in the native protein when purified from nuclear envelopes of mouse neuroblastoma Neuro2a cells. Five phosphorylation sites were detected by nano-electrospray mass spectrometric analysis of tryptic LAP 2 beta peptides using parent ion scans specific for phosphopeptides. By mass spectrometric sequencing of these peptides, we identified as phosphorylated residues Thr 74, Thr 159, Ser 176, and Ser 179. Two of the phosphorylation sites, Thr 74 (within a region known to bind chromatin) and Thr 159, are part of consensus sequences of proline-directed kinases. Ser 179 is part of a consensus site for protein kinase C which is able to highly phosphorylate LAP 2 beta in vitro. Three phosphorylation sites, Thr 159, Ser 176, and Ser 179, are located within a stretch of 20 amino acids, thereby forming a highly phosphorylated protein domain which may integrate signaling by multiple protein kinases. Additionally, we identified for the first time at the protein level the LAP 2 splice variant LAP 2 epsilon in nuclear envelopes.
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Affiliation(s)
- M Dreger
- AG Neurochemie, Institut für Biochemie, Freie Universität Berlin, Germany
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48
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Schneider U, Mini T, Jenö P, Fisher PA, Stuurman N. Phosphorylation of the major Drosophila lamin in vivo: site identification during both M-phase (meiosis) and interphase by electrospray ionization tandem mass spectrometry. Biochemistry 1999; 38:4620-32. [PMID: 10194384 DOI: 10.1021/bi9827060] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phosphorylation can have profound effects on the properties of nuclear lamins. For instance, phosphorylation of specific sites on mammalian lamins drastically alters their propensity to polymerize. Relatively little is known about the effects of phosphorylation during interphase and about phosphorylation of invertebrate nuclear lamins. Here, using electrospray ionization tandem mass spectrometry, we determined the phosphorylation sites of both interphase and M-phase isoforms of nuclear lamin Dm from Drosophila melanogaster. Interphase lamins are phosphorylated at three sites: two of these sites (Ser25 and a site located between residues 430 and 438) flank the alpha-helical rod domain, whereas the third site (Ser595) is located close to the C-terminus. The M-phase lamin isoform is phosphorylated predominantly at Ser45, a residue contained within a sequence matching the consensus site for phosphorylation by cdc2 kinase. Our study confirms the important role in vivo for cdc2 kinase in M-phase disassembly of nuclear lamins and provides the basis for understanding Drosophila lamin phosphorylation during interphase.
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Affiliation(s)
- U Schneider
- Department of Biochemistry, Biozentrum of the University of Basel, Switzerland
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49
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Collas P. Sequential PKC- and Cdc2-mediated phosphorylation events elicit zebrafish nuclear envelope disassembly. J Cell Sci 1999; 112 ( Pt 6):977-87. [PMID: 10036247 DOI: 10.1242/jcs.112.6.977] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular markers of the zebrafish inner nuclear membrane (NEP55) and nuclear lamina (L68) were identified, partially characterized and used to demonstrate that disassembly of the zebrafish nuclear envelope requires sequential phosphorylation events by first PKC, then Cdc2 kinase. NEP55 and L68 are immunologically and functionally related to human LAP2beta and lamin B, respectively. Exposure of zebrafish nuclei to meiotic cytosol elicits rapid phosphorylation of NEP55 and L68, and disassembly of both proteins. L68 phosphorylation is completely inhibited by simultaneous inhibition of Cdc2 and PKC and only partially blocked by inhibition of either kinase. NEP55 phosphorylation is completely prevented by inhibition or immunodepletion of cytosolic Cdc2. Inhibition of cAMP-dependent kinase, MEK or CaM kinase II does not affect NEP55 or L68 phosphorylation. In vitro, nuclear envelope disassembly requires phosphorylation of NEP55 and L68 by both mammalian PKC and Cdc2. Inhibition of either kinase is sufficient to abolish NE disassembly. Furthermore, novel two-step phosphorylation assays in cytosol and in vitro indicate that PKC-mediated phosphorylation of L68 prior to Cdc2-mediated phosphorylation of L68 and NEP55 is essential to elicit nuclear envelope breakdown. Phosphorylation elicited by Cdc2 prior to PKC prevents nuclear envelope disassembly even though NEP55 is phosphorylated. The results indicate that sequential phosphorylation events elicited by PKC, followed by Cdc2, are required for zebrafish nuclear disassembly. They also argue that phosphorylation of inner nuclear membrane integral proteins is not sufficient to promote nuclear envelope breakdown, and suggest a multiple-level regulation of disassembly of nuclear envelope components during meiosis and at mitosis.
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Affiliation(s)
- P Collas
- Department of Biochemistry, Norwegian College of Veterinary Medicine, and Institute of Medical Biochemistry, University of Oslo, PO Box 1112, Blindern, Norway.
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50
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Lourim D, Krohne G. Chromatin binding and polymerization of the endogenous Xenopus egg lamins: the opposing effects of glycogen and ATP. J Cell Sci 1998; 111 ( Pt 24):3675-86. [PMID: 9819358 DOI: 10.1242/jcs.111.24.3675] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously identified and quantitated three B-type lamin isoforms present in the nuclei of mature Xenopus laevis oocytes, and in cell-free egg extracts. As Xenopus egg extracts are frequently used to analyze nuclear envelope assembly and lamina functions, we felt it was imperative that the polymerization and chromatin-binding properties of the endogenous B-type egg lamins be investigated. While we have demonstrated that soluble B-type lamins bind to chromatin, we have also observed that the polymerization of egg lamins does not require membranes or chromatin. Lamin assembly is enhanced by the addition of glycogen/glucose, or by the depletion of ATP from the extract. Moreover, the polymerization of egg cytosol lamins and their binding to demembranated sperm or chromatin assembled from naked lambda-DNA is inhibited by an ATP regeneration system. These ATP-dependent inhibitory activities can be overcome by the coaddition of glycogen to egg cytosol. We have observed that glycogen does not alter ATP levels during cytosol incubation, but rather, as glycogen-enhanced lamin polymerization is inhibited by okadaic acid, we conclude that glycogen activates protein phosphatases. Because protein phosphatase 1 (PP1) is the only phosphatase known to be specifically regulated by glycogen our data indicate that PP1 is involved in lamin polymerization. Our results show that ATP and glycogen effect lamin polymerization and chromatin binding by separate and opposing mechanisms.
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Affiliation(s)
- D Lourim
- Division of Electron Microscopy, Biocenter of the University of W urzburg, Am Hubland, D-97074 Würzburg, Germany
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